src/stdlib/SDL_malloc.c
author Sam Lantinga
Sun, 28 May 2006 13:04:16 +0000
branchSDL-1.3
changeset 1662 782fd950bd46
parent 1465 8dfa9a6d69a5
child 1668 4da1ee79c9af
permissions -rw-r--r--
Revamp of the video system in progress - adding support for multiple displays, multiple windows, and a full video mode selection API.

WARNING: None of the video drivers have been updated for the new API yet! The API is still under design and very fluid.

The code is now run through a consistent indent format:
indent -i4 -nut -nsc -br -ce

The headers are being converted to automatically generate doxygen documentation.
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2006 Sam Lantinga
     4 
     5     This library is free software; you can redistribute it and/or
     6     modify it under the terms of the GNU Lesser General Public
     7     License as published by the Free Software Foundation; either
     8     version 2.1 of the License, or (at your option) any later version.
     9 
    10     This library is distributed in the hope that it will be useful,
    11     but WITHOUT ANY WARRANTY; without even the implied warranty of
    12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13     Lesser General Public License for more details.
    14 
    15     You should have received a copy of the GNU Lesser General Public
    16     License along with this library; if not, write to the Free Software
    17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
    18 
    19     Sam Lantinga
    20     slouken@libsdl.org
    21 */
    22 #include "SDL_config.h"
    23 
    24 /* This file contains portable memory management functions for SDL */
    25 
    26 #include "SDL_stdinc.h"
    27 
    28 #ifndef HAVE_MALLOC
    29 
    30 #define LACKS_SYS_TYPES_H
    31 #define LACKS_STDIO_H
    32 #define LACKS_STRINGS_H
    33 #define LACKS_STRING_H
    34 #define LACKS_STDLIB_H
    35 #define ABORT
    36 
    37 /*
    38   This is a version (aka dlmalloc) of malloc/free/realloc written by
    39   Doug Lea and released to the public domain, as explained at
    40   http://creativecommons.org/licenses/publicdomain.  Send questions,
    41   comments, complaints, performance data, etc to dl@cs.oswego.edu
    42 
    43 * Version 2.8.3 Thu Sep 22 11:16:15 2005  Doug Lea  (dl at gee)
    44 
    45    Note: There may be an updated version of this malloc obtainable at
    46            ftp://gee.cs.oswego.edu/pub/misc/malloc.c
    47          Check before installing!
    48 
    49 * Quickstart
    50 
    51   This library is all in one file to simplify the most common usage:
    52   ftp it, compile it (-O3), and link it into another program. All of
    53   the compile-time options default to reasonable values for use on
    54   most platforms.  You might later want to step through various
    55   compile-time and dynamic tuning options.
    56 
    57   For convenience, an include file for code using this malloc is at:
    58      ftp://gee.cs.oswego.edu/pub/misc/malloc-2.8.3.h
    59   You don't really need this .h file unless you call functions not
    60   defined in your system include files.  The .h file contains only the
    61   excerpts from this file needed for using this malloc on ANSI C/C++
    62   systems, so long as you haven't changed compile-time options about
    63   naming and tuning parameters.  If you do, then you can create your
    64   own malloc.h that does include all settings by cutting at the point
    65   indicated below. Note that you may already by default be using a C
    66   library containing a malloc that is based on some version of this
    67   malloc (for example in linux). You might still want to use the one
    68   in this file to customize settings or to avoid overheads associated
    69   with library versions.
    70 
    71 * Vital statistics:
    72 
    73   Supported pointer/size_t representation:       4 or 8 bytes
    74        size_t MUST be an unsigned type of the same width as
    75        pointers. (If you are using an ancient system that declares
    76        size_t as a signed type, or need it to be a different width
    77        than pointers, you can use a previous release of this malloc
    78        (e.g. 2.7.2) supporting these.)
    79 
    80   Alignment:                                     8 bytes (default)
    81        This suffices for nearly all current machines and C compilers.
    82        However, you can define MALLOC_ALIGNMENT to be wider than this
    83        if necessary (up to 128bytes), at the expense of using more space.
    84 
    85   Minimum overhead per allocated chunk:   4 or  8 bytes (if 4byte sizes)
    86                                           8 or 16 bytes (if 8byte sizes)
    87        Each malloced chunk has a hidden word of overhead holding size
    88        and status information, and additional cross-check word
    89        if FOOTERS is defined.
    90 
    91   Minimum allocated size: 4-byte ptrs:  16 bytes    (including overhead)
    92                           8-byte ptrs:  32 bytes    (including overhead)
    93 
    94        Even a request for zero bytes (i.e., malloc(0)) returns a
    95        pointer to something of the minimum allocatable size.
    96        The maximum overhead wastage (i.e., number of extra bytes
    97        allocated than were requested in malloc) is less than or equal
    98        to the minimum size, except for requests >= mmap_threshold that
    99        are serviced via mmap(), where the worst case wastage is about
   100        32 bytes plus the remainder from a system page (the minimal
   101        mmap unit); typically 4096 or 8192 bytes.
   102 
   103   Security: static-safe; optionally more or less
   104        The "security" of malloc refers to the ability of malicious
   105        code to accentuate the effects of errors (for example, freeing
   106        space that is not currently malloc'ed or overwriting past the
   107        ends of chunks) in code that calls malloc.  This malloc
   108        guarantees not to modify any memory locations below the base of
   109        heap, i.e., static variables, even in the presence of usage
   110        errors.  The routines additionally detect most improper frees
   111        and reallocs.  All this holds as long as the static bookkeeping
   112        for malloc itself is not corrupted by some other means.  This
   113        is only one aspect of security -- these checks do not, and
   114        cannot, detect all possible programming errors.
   115 
   116        If FOOTERS is defined nonzero, then each allocated chunk
   117        carries an additional check word to verify that it was malloced
   118        from its space.  These check words are the same within each
   119        execution of a program using malloc, but differ across
   120        executions, so externally crafted fake chunks cannot be
   121        freed. This improves security by rejecting frees/reallocs that
   122        could corrupt heap memory, in addition to the checks preventing
   123        writes to statics that are always on.  This may further improve
   124        security at the expense of time and space overhead.  (Note that
   125        FOOTERS may also be worth using with MSPACES.)
   126 
   127        By default detected errors cause the program to abort (calling
   128        "abort()"). You can override this to instead proceed past
   129        errors by defining PROCEED_ON_ERROR.  In this case, a bad free
   130        has no effect, and a malloc that encounters a bad address
   131        caused by user overwrites will ignore the bad address by
   132        dropping pointers and indices to all known memory. This may
   133        be appropriate for programs that should continue if at all
   134        possible in the face of programming errors, although they may
   135        run out of memory because dropped memory is never reclaimed.
   136 
   137        If you don't like either of these options, you can define
   138        CORRUPTION_ERROR_ACTION and USAGE_ERROR_ACTION to do anything
   139        else. And if if you are sure that your program using malloc has
   140        no errors or vulnerabilities, you can define INSECURE to 1,
   141        which might (or might not) provide a small performance improvement.
   142 
   143   Thread-safety: NOT thread-safe unless USE_LOCKS defined
   144        When USE_LOCKS is defined, each public call to malloc, free,
   145        etc is surrounded with either a pthread mutex or a win32
   146        spinlock (depending on WIN32). This is not especially fast, and
   147        can be a major bottleneck.  It is designed only to provide
   148        minimal protection in concurrent environments, and to provide a
   149        basis for extensions.  If you are using malloc in a concurrent
   150        program, consider instead using ptmalloc, which is derived from
   151        a version of this malloc. (See http://www.malloc.de).
   152 
   153   System requirements: Any combination of MORECORE and/or MMAP/MUNMAP
   154        This malloc can use unix sbrk or any emulation (invoked using
   155        the CALL_MORECORE macro) and/or mmap/munmap or any emulation
   156        (invoked using CALL_MMAP/CALL_MUNMAP) to get and release system
   157        memory.  On most unix systems, it tends to work best if both
   158        MORECORE and MMAP are enabled.  On Win32, it uses emulations
   159        based on VirtualAlloc. It also uses common C library functions
   160        like memset.
   161 
   162   Compliance: I believe it is compliant with the Single Unix Specification
   163        (See http://www.unix.org). Also SVID/XPG, ANSI C, and probably
   164        others as well.
   165 
   166 * Overview of algorithms
   167 
   168   This is not the fastest, most space-conserving, most portable, or
   169   most tunable malloc ever written. However it is among the fastest
   170   while also being among the most space-conserving, portable and
   171   tunable.  Consistent balance across these factors results in a good
   172   general-purpose allocator for malloc-intensive programs.
   173 
   174   In most ways, this malloc is a best-fit allocator. Generally, it
   175   chooses the best-fitting existing chunk for a request, with ties
   176   broken in approximately least-recently-used order. (This strategy
   177   normally maintains low fragmentation.) However, for requests less
   178   than 256bytes, it deviates from best-fit when there is not an
   179   exactly fitting available chunk by preferring to use space adjacent
   180   to that used for the previous small request, as well as by breaking
   181   ties in approximately most-recently-used order. (These enhance
   182   locality of series of small allocations.)  And for very large requests
   183   (>= 256Kb by default), it relies on system memory mapping
   184   facilities, if supported.  (This helps avoid carrying around and
   185   possibly fragmenting memory used only for large chunks.)
   186 
   187   All operations (except malloc_stats and mallinfo) have execution
   188   times that are bounded by a constant factor of the number of bits in
   189   a size_t, not counting any clearing in calloc or copying in realloc,
   190   or actions surrounding MORECORE and MMAP that have times
   191   proportional to the number of non-contiguous regions returned by
   192   system allocation routines, which is often just 1.
   193 
   194   The implementation is not very modular and seriously overuses
   195   macros. Perhaps someday all C compilers will do as good a job
   196   inlining modular code as can now be done by brute-force expansion,
   197   but now, enough of them seem not to.
   198 
   199   Some compilers issue a lot of warnings about code that is
   200   dead/unreachable only on some platforms, and also about intentional
   201   uses of negation on unsigned types. All known cases of each can be
   202   ignored.
   203 
   204   For a longer but out of date high-level description, see
   205      http://gee.cs.oswego.edu/dl/html/malloc.html
   206 
   207 * MSPACES
   208   If MSPACES is defined, then in addition to malloc, free, etc.,
   209   this file also defines mspace_malloc, mspace_free, etc. These
   210   are versions of malloc routines that take an "mspace" argument
   211   obtained using create_mspace, to control all internal bookkeeping.
   212   If ONLY_MSPACES is defined, only these versions are compiled.
   213   So if you would like to use this allocator for only some allocations,
   214   and your system malloc for others, you can compile with
   215   ONLY_MSPACES and then do something like...
   216     static mspace mymspace = create_mspace(0,0); // for example
   217     #define mymalloc(bytes)  mspace_malloc(mymspace, bytes)
   218 
   219   (Note: If you only need one instance of an mspace, you can instead
   220   use "USE_DL_PREFIX" to relabel the global malloc.)
   221 
   222   You can similarly create thread-local allocators by storing
   223   mspaces as thread-locals. For example:
   224     static __thread mspace tlms = 0;
   225     void*  tlmalloc(size_t bytes) {
   226       if (tlms == 0) tlms = create_mspace(0, 0);
   227       return mspace_malloc(tlms, bytes);
   228     }
   229     void  tlfree(void* mem) { mspace_free(tlms, mem); }
   230 
   231   Unless FOOTERS is defined, each mspace is completely independent.
   232   You cannot allocate from one and free to another (although
   233   conformance is only weakly checked, so usage errors are not always
   234   caught). If FOOTERS is defined, then each chunk carries around a tag
   235   indicating its originating mspace, and frees are directed to their
   236   originating spaces.
   237 
   238  -------------------------  Compile-time options ---------------------------
   239 
   240 Be careful in setting #define values for numerical constants of type
   241 size_t. On some systems, literal values are not automatically extended
   242 to size_t precision unless they are explicitly casted.
   243 
   244 WIN32                    default: defined if _WIN32 defined
   245   Defining WIN32 sets up defaults for MS environment and compilers.
   246   Otherwise defaults are for unix.
   247 
   248 MALLOC_ALIGNMENT         default: (size_t)8
   249   Controls the minimum alignment for malloc'ed chunks.  It must be a
   250   power of two and at least 8, even on machines for which smaller
   251   alignments would suffice. It may be defined as larger than this
   252   though. Note however that code and data structures are optimized for
   253   the case of 8-byte alignment.
   254 
   255 MSPACES                  default: 0 (false)
   256   If true, compile in support for independent allocation spaces.
   257   This is only supported if HAVE_MMAP is true.
   258 
   259 ONLY_MSPACES             default: 0 (false)
   260   If true, only compile in mspace versions, not regular versions.
   261 
   262 USE_LOCKS                default: 0 (false)
   263   Causes each call to each public routine to be surrounded with
   264   pthread or WIN32 mutex lock/unlock. (If set true, this can be
   265   overridden on a per-mspace basis for mspace versions.)
   266 
   267 FOOTERS                  default: 0
   268   If true, provide extra checking and dispatching by placing
   269   information in the footers of allocated chunks. This adds
   270   space and time overhead.
   271 
   272 INSECURE                 default: 0
   273   If true, omit checks for usage errors and heap space overwrites.
   274 
   275 USE_DL_PREFIX            default: NOT defined
   276   Causes compiler to prefix all public routines with the string 'dl'.
   277   This can be useful when you only want to use this malloc in one part
   278   of a program, using your regular system malloc elsewhere.
   279 
   280 ABORT                    default: defined as abort()
   281   Defines how to abort on failed checks.  On most systems, a failed
   282   check cannot die with an "assert" or even print an informative
   283   message, because the underlying print routines in turn call malloc,
   284   which will fail again.  Generally, the best policy is to simply call
   285   abort(). It's not very useful to do more than this because many
   286   errors due to overwriting will show up as address faults (null, odd
   287   addresses etc) rather than malloc-triggered checks, so will also
   288   abort.  Also, most compilers know that abort() does not return, so
   289   can better optimize code conditionally calling it.
   290 
   291 PROCEED_ON_ERROR           default: defined as 0 (false)
   292   Controls whether detected bad addresses cause them to bypassed
   293   rather than aborting. If set, detected bad arguments to free and
   294   realloc are ignored. And all bookkeeping information is zeroed out
   295   upon a detected overwrite of freed heap space, thus losing the
   296   ability to ever return it from malloc again, but enabling the
   297   application to proceed. If PROCEED_ON_ERROR is defined, the
   298   static variable malloc_corruption_error_count is compiled in
   299   and can be examined to see if errors have occurred. This option
   300   generates slower code than the default abort policy.
   301 
   302 DEBUG                    default: NOT defined
   303   The DEBUG setting is mainly intended for people trying to modify
   304   this code or diagnose problems when porting to new platforms.
   305   However, it may also be able to better isolate user errors than just
   306   using runtime checks.  The assertions in the check routines spell
   307   out in more detail the assumptions and invariants underlying the
   308   algorithms.  The checking is fairly extensive, and will slow down
   309   execution noticeably. Calling malloc_stats or mallinfo with DEBUG
   310   set will attempt to check every non-mmapped allocated and free chunk
   311   in the course of computing the summaries.
   312 
   313 ABORT_ON_ASSERT_FAILURE   default: defined as 1 (true)
   314   Debugging assertion failures can be nearly impossible if your
   315   version of the assert macro causes malloc to be called, which will
   316   lead to a cascade of further failures, blowing the runtime stack.
   317   ABORT_ON_ASSERT_FAILURE cause assertions failures to call abort(),
   318   which will usually make debugging easier.
   319 
   320 MALLOC_FAILURE_ACTION     default: sets errno to ENOMEM, or no-op on win32
   321   The action to take before "return 0" when malloc fails to be able to
   322   return memory because there is none available.
   323 
   324 HAVE_MORECORE             default: 1 (true) unless win32 or ONLY_MSPACES
   325   True if this system supports sbrk or an emulation of it.
   326 
   327 MORECORE                  default: sbrk
   328   The name of the sbrk-style system routine to call to obtain more
   329   memory.  See below for guidance on writing custom MORECORE
   330   functions. The type of the argument to sbrk/MORECORE varies across
   331   systems.  It cannot be size_t, because it supports negative
   332   arguments, so it is normally the signed type of the same width as
   333   size_t (sometimes declared as "intptr_t").  It doesn't much matter
   334   though. Internally, we only call it with arguments less than half
   335   the max value of a size_t, which should work across all reasonable
   336   possibilities, although sometimes generating compiler warnings.  See
   337   near the end of this file for guidelines for creating a custom
   338   version of MORECORE.
   339 
   340 MORECORE_CONTIGUOUS       default: 1 (true)
   341   If true, take advantage of fact that consecutive calls to MORECORE
   342   with positive arguments always return contiguous increasing
   343   addresses.  This is true of unix sbrk. It does not hurt too much to
   344   set it true anyway, since malloc copes with non-contiguities.
   345   Setting it false when definitely non-contiguous saves time
   346   and possibly wasted space it would take to discover this though.
   347 
   348 MORECORE_CANNOT_TRIM      default: NOT defined
   349   True if MORECORE cannot release space back to the system when given
   350   negative arguments. This is generally necessary only if you are
   351   using a hand-crafted MORECORE function that cannot handle negative
   352   arguments.
   353 
   354 HAVE_MMAP                 default: 1 (true)
   355   True if this system supports mmap or an emulation of it.  If so, and
   356   HAVE_MORECORE is not true, MMAP is used for all system
   357   allocation. If set and HAVE_MORECORE is true as well, MMAP is
   358   primarily used to directly allocate very large blocks. It is also
   359   used as a backup strategy in cases where MORECORE fails to provide
   360   space from system. Note: A single call to MUNMAP is assumed to be
   361   able to unmap memory that may have be allocated using multiple calls
   362   to MMAP, so long as they are adjacent.
   363 
   364 HAVE_MREMAP               default: 1 on linux, else 0
   365   If true realloc() uses mremap() to re-allocate large blocks and
   366   extend or shrink allocation spaces.
   367 
   368 MMAP_CLEARS               default: 1 on unix
   369   True if mmap clears memory so calloc doesn't need to. This is true
   370   for standard unix mmap using /dev/zero.
   371 
   372 USE_BUILTIN_FFS            default: 0 (i.e., not used)
   373   Causes malloc to use the builtin ffs() function to compute indices.
   374   Some compilers may recognize and intrinsify ffs to be faster than the
   375   supplied C version. Also, the case of x86 using gcc is special-cased
   376   to an asm instruction, so is already as fast as it can be, and so
   377   this setting has no effect. (On most x86s, the asm version is only
   378   slightly faster than the C version.)
   379 
   380 malloc_getpagesize         default: derive from system includes, or 4096.
   381   The system page size. To the extent possible, this malloc manages
   382   memory from the system in page-size units.  This may be (and
   383   usually is) a function rather than a constant. This is ignored
   384   if WIN32, where page size is determined using getSystemInfo during
   385   initialization.
   386 
   387 USE_DEV_RANDOM             default: 0 (i.e., not used)
   388   Causes malloc to use /dev/random to initialize secure magic seed for
   389   stamping footers. Otherwise, the current time is used.
   390 
   391 NO_MALLINFO                default: 0
   392   If defined, don't compile "mallinfo". This can be a simple way
   393   of dealing with mismatches between system declarations and
   394   those in this file.
   395 
   396 MALLINFO_FIELD_TYPE        default: size_t
   397   The type of the fields in the mallinfo struct. This was originally
   398   defined as "int" in SVID etc, but is more usefully defined as
   399   size_t. The value is used only if  HAVE_USR_INCLUDE_MALLOC_H is not set
   400 
   401 REALLOC_ZERO_BYTES_FREES    default: not defined
   402   This should be set if a call to realloc with zero bytes should 
   403   be the same as a call to free. Some people think it should. Otherwise, 
   404   since this malloc returns a unique pointer for malloc(0), so does 
   405   realloc(p, 0).
   406 
   407 LACKS_UNISTD_H, LACKS_FCNTL_H, LACKS_SYS_PARAM_H, LACKS_SYS_MMAN_H
   408 LACKS_STRINGS_H, LACKS_STRING_H, LACKS_SYS_TYPES_H,  LACKS_ERRNO_H
   409 LACKS_STDLIB_H                default: NOT defined unless on WIN32
   410   Define these if your system does not have these header files.
   411   You might need to manually insert some of the declarations they provide.
   412 
   413 DEFAULT_GRANULARITY        default: page size if MORECORE_CONTIGUOUS,
   414                                 system_info.dwAllocationGranularity in WIN32,
   415                                 otherwise 64K.
   416       Also settable using mallopt(M_GRANULARITY, x)
   417   The unit for allocating and deallocating memory from the system.  On
   418   most systems with contiguous MORECORE, there is no reason to
   419   make this more than a page. However, systems with MMAP tend to
   420   either require or encourage larger granularities.  You can increase
   421   this value to prevent system allocation functions to be called so
   422   often, especially if they are slow.  The value must be at least one
   423   page and must be a power of two.  Setting to 0 causes initialization
   424   to either page size or win32 region size.  (Note: In previous
   425   versions of malloc, the equivalent of this option was called
   426   "TOP_PAD")
   427 
   428 DEFAULT_TRIM_THRESHOLD    default: 2MB
   429       Also settable using mallopt(M_TRIM_THRESHOLD, x)
   430   The maximum amount of unused top-most memory to keep before
   431   releasing via malloc_trim in free().  Automatic trimming is mainly
   432   useful in long-lived programs using contiguous MORECORE.  Because
   433   trimming via sbrk can be slow on some systems, and can sometimes be
   434   wasteful (in cases where programs immediately afterward allocate
   435   more large chunks) the value should be high enough so that your
   436   overall system performance would improve by releasing this much
   437   memory.  As a rough guide, you might set to a value close to the
   438   average size of a process (program) running on your system.
   439   Releasing this much memory would allow such a process to run in
   440   memory.  Generally, it is worth tuning trim thresholds when a
   441   program undergoes phases where several large chunks are allocated
   442   and released in ways that can reuse each other's storage, perhaps
   443   mixed with phases where there are no such chunks at all. The trim
   444   value must be greater than page size to have any useful effect.  To
   445   disable trimming completely, you can set to MAX_SIZE_T. Note that the trick
   446   some people use of mallocing a huge space and then freeing it at
   447   program startup, in an attempt to reserve system memory, doesn't
   448   have the intended effect under automatic trimming, since that memory
   449   will immediately be returned to the system.
   450 
   451 DEFAULT_MMAP_THRESHOLD       default: 256K
   452       Also settable using mallopt(M_MMAP_THRESHOLD, x)
   453   The request size threshold for using MMAP to directly service a
   454   request. Requests of at least this size that cannot be allocated
   455   using already-existing space will be serviced via mmap.  (If enough
   456   normal freed space already exists it is used instead.)  Using mmap
   457   segregates relatively large chunks of memory so that they can be
   458   individually obtained and released from the host system. A request
   459   serviced through mmap is never reused by any other request (at least
   460   not directly; the system may just so happen to remap successive
   461   requests to the same locations).  Segregating space in this way has
   462   the benefits that: Mmapped space can always be individually released
   463   back to the system, which helps keep the system level memory demands
   464   of a long-lived program low.  Also, mapped memory doesn't become
   465   `locked' between other chunks, as can happen with normally allocated
   466   chunks, which means that even trimming via malloc_trim would not
   467   release them.  However, it has the disadvantage that the space
   468   cannot be reclaimed, consolidated, and then used to service later
   469   requests, as happens with normal chunks.  The advantages of mmap
   470   nearly always outweigh disadvantages for "large" chunks, but the
   471   value of "large" may vary across systems.  The default is an
   472   empirically derived value that works well in most systems. You can
   473   disable mmap by setting to MAX_SIZE_T.
   474 
   475 */
   476 
   477 #ifndef WIN32
   478 #ifdef _WIN32
   479 #define WIN32 1
   480 #endif /* _WIN32 */
   481 #endif /* WIN32 */
   482 #ifdef WIN32
   483 #define WIN32_LEAN_AND_MEAN
   484 #include <windows.h>
   485 #define HAVE_MMAP 1
   486 #define HAVE_MORECORE 0
   487 #define LACKS_UNISTD_H
   488 #define LACKS_SYS_PARAM_H
   489 #define LACKS_SYS_MMAN_H
   490 #define LACKS_STRING_H
   491 #define LACKS_STRINGS_H
   492 #define LACKS_SYS_TYPES_H
   493 #define LACKS_ERRNO_H
   494 #define LACKS_FCNTL_H
   495 #define MALLOC_FAILURE_ACTION
   496 #define MMAP_CLEARS 0           /* WINCE and some others apparently don't clear */
   497 #endif /* WIN32 */
   498 
   499 #if defined(DARWIN) || defined(_DARWIN)
   500 /* Mac OSX docs advise not to use sbrk; it seems better to use mmap */
   501 #ifndef HAVE_MORECORE
   502 #define HAVE_MORECORE 0
   503 #define HAVE_MMAP 1
   504 #endif /* HAVE_MORECORE */
   505 #endif /* DARWIN */
   506 
   507 #ifndef LACKS_SYS_TYPES_H
   508 #include <sys/types.h>          /* For size_t */
   509 #endif /* LACKS_SYS_TYPES_H */
   510 
   511 /* The maximum possible size_t value has all bits set */
   512 #define MAX_SIZE_T           (~(size_t)0)
   513 
   514 #ifndef ONLY_MSPACES
   515 #define ONLY_MSPACES 0
   516 #endif /* ONLY_MSPACES */
   517 #ifndef MSPACES
   518 #if ONLY_MSPACES
   519 #define MSPACES 1
   520 #else /* ONLY_MSPACES */
   521 #define MSPACES 0
   522 #endif /* ONLY_MSPACES */
   523 #endif /* MSPACES */
   524 #ifndef MALLOC_ALIGNMENT
   525 #define MALLOC_ALIGNMENT ((size_t)8U)
   526 #endif /* MALLOC_ALIGNMENT */
   527 #ifndef FOOTERS
   528 #define FOOTERS 0
   529 #endif /* FOOTERS */
   530 #ifndef ABORT
   531 #define ABORT  abort()
   532 #endif /* ABORT */
   533 #ifndef ABORT_ON_ASSERT_FAILURE
   534 #define ABORT_ON_ASSERT_FAILURE 1
   535 #endif /* ABORT_ON_ASSERT_FAILURE */
   536 #ifndef PROCEED_ON_ERROR
   537 #define PROCEED_ON_ERROR 0
   538 #endif /* PROCEED_ON_ERROR */
   539 #ifndef USE_LOCKS
   540 #define USE_LOCKS 0
   541 #endif /* USE_LOCKS */
   542 #ifndef INSECURE
   543 #define INSECURE 0
   544 #endif /* INSECURE */
   545 #ifndef HAVE_MMAP
   546 #define HAVE_MMAP 1
   547 #endif /* HAVE_MMAP */
   548 #ifndef MMAP_CLEARS
   549 #define MMAP_CLEARS 1
   550 #endif /* MMAP_CLEARS */
   551 #ifndef HAVE_MREMAP
   552 #ifdef linux
   553 #define HAVE_MREMAP 1
   554 #else /* linux */
   555 #define HAVE_MREMAP 0
   556 #endif /* linux */
   557 #endif /* HAVE_MREMAP */
   558 #ifndef MALLOC_FAILURE_ACTION
   559 #define MALLOC_FAILURE_ACTION  errno = ENOMEM;
   560 #endif /* MALLOC_FAILURE_ACTION */
   561 #ifndef HAVE_MORECORE
   562 #if ONLY_MSPACES
   563 #define HAVE_MORECORE 0
   564 #else /* ONLY_MSPACES */
   565 #define HAVE_MORECORE 1
   566 #endif /* ONLY_MSPACES */
   567 #endif /* HAVE_MORECORE */
   568 #if !HAVE_MORECORE
   569 #define MORECORE_CONTIGUOUS 0
   570 #else /* !HAVE_MORECORE */
   571 #ifndef MORECORE
   572 #define MORECORE sbrk
   573 #endif /* MORECORE */
   574 #ifndef MORECORE_CONTIGUOUS
   575 #define MORECORE_CONTIGUOUS 1
   576 #endif /* MORECORE_CONTIGUOUS */
   577 #endif /* HAVE_MORECORE */
   578 #ifndef DEFAULT_GRANULARITY
   579 #if MORECORE_CONTIGUOUS
   580 #define DEFAULT_GRANULARITY (0) /* 0 means to compute in init_mparams */
   581 #else /* MORECORE_CONTIGUOUS */
   582 #define DEFAULT_GRANULARITY ((size_t)64U * (size_t)1024U)
   583 #endif /* MORECORE_CONTIGUOUS */
   584 #endif /* DEFAULT_GRANULARITY */
   585 #ifndef DEFAULT_TRIM_THRESHOLD
   586 #ifndef MORECORE_CANNOT_TRIM
   587 #define DEFAULT_TRIM_THRESHOLD ((size_t)2U * (size_t)1024U * (size_t)1024U)
   588 #else /* MORECORE_CANNOT_TRIM */
   589 #define DEFAULT_TRIM_THRESHOLD MAX_SIZE_T
   590 #endif /* MORECORE_CANNOT_TRIM */
   591 #endif /* DEFAULT_TRIM_THRESHOLD */
   592 #ifndef DEFAULT_MMAP_THRESHOLD
   593 #if HAVE_MMAP
   594 #define DEFAULT_MMAP_THRESHOLD ((size_t)256U * (size_t)1024U)
   595 #else /* HAVE_MMAP */
   596 #define DEFAULT_MMAP_THRESHOLD MAX_SIZE_T
   597 #endif /* HAVE_MMAP */
   598 #endif /* DEFAULT_MMAP_THRESHOLD */
   599 #ifndef USE_BUILTIN_FFS
   600 #define USE_BUILTIN_FFS 0
   601 #endif /* USE_BUILTIN_FFS */
   602 #ifndef USE_DEV_RANDOM
   603 #define USE_DEV_RANDOM 0
   604 #endif /* USE_DEV_RANDOM */
   605 #ifndef NO_MALLINFO
   606 #define NO_MALLINFO 0
   607 #endif /* NO_MALLINFO */
   608 #ifndef MALLINFO_FIELD_TYPE
   609 #define MALLINFO_FIELD_TYPE size_t
   610 #endif /* MALLINFO_FIELD_TYPE */
   611 
   612 #define memset	SDL_memset
   613 #define memcpy	SDL_memcpy
   614 #define malloc	SDL_malloc
   615 #define calloc	SDL_calloc
   616 #define realloc	SDL_realloc
   617 #define free	SDL_free
   618 
   619 /*
   620   mallopt tuning options.  SVID/XPG defines four standard parameter
   621   numbers for mallopt, normally defined in malloc.h.  None of these
   622   are used in this malloc, so setting them has no effect. But this
   623   malloc does support the following options.
   624 */
   625 
   626 #define M_TRIM_THRESHOLD     (-1)
   627 #define M_GRANULARITY        (-2)
   628 #define M_MMAP_THRESHOLD     (-3)
   629 
   630 /* ------------------------ Mallinfo declarations ------------------------ */
   631 
   632 #if !NO_MALLINFO
   633 /*
   634   This version of malloc supports the standard SVID/XPG mallinfo
   635   routine that returns a struct containing usage properties and
   636   statistics. It should work on any system that has a
   637   /usr/include/malloc.h defining struct mallinfo.  The main
   638   declaration needed is the mallinfo struct that is returned (by-copy)
   639   by mallinfo().  The malloinfo struct contains a bunch of fields that
   640   are not even meaningful in this version of malloc.  These fields are
   641   are instead filled by mallinfo() with other numbers that might be of
   642   interest.
   643 
   644   HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
   645   /usr/include/malloc.h file that includes a declaration of struct
   646   mallinfo.  If so, it is included; else a compliant version is
   647   declared below.  These must be precisely the same for mallinfo() to
   648   work.  The original SVID version of this struct, defined on most
   649   systems with mallinfo, declares all fields as ints. But some others
   650   define as unsigned long. If your system defines the fields using a
   651   type of different width than listed here, you MUST #include your
   652   system version and #define HAVE_USR_INCLUDE_MALLOC_H.
   653 */
   654 
   655 /* #define HAVE_USR_INCLUDE_MALLOC_H */
   656 
   657 #ifdef HAVE_USR_INCLUDE_MALLOC_H
   658 #include "/usr/include/malloc.h"
   659 #else /* HAVE_USR_INCLUDE_MALLOC_H */
   660 
   661 struct mallinfo
   662 {
   663     MALLINFO_FIELD_TYPE arena;  /* non-mmapped space allocated from system */
   664     MALLINFO_FIELD_TYPE ordblks;        /* number of free chunks */
   665     MALLINFO_FIELD_TYPE smblks; /* always 0 */
   666     MALLINFO_FIELD_TYPE hblks;  /* always 0 */
   667     MALLINFO_FIELD_TYPE hblkhd; /* space in mmapped regions */
   668     MALLINFO_FIELD_TYPE usmblks;        /* maximum total allocated space */
   669     MALLINFO_FIELD_TYPE fsmblks;        /* always 0 */
   670     MALLINFO_FIELD_TYPE uordblks;       /* total allocated space */
   671     MALLINFO_FIELD_TYPE fordblks;       /* total free space */
   672     MALLINFO_FIELD_TYPE keepcost;       /* releasable (via malloc_trim) space */
   673 };
   674 
   675 #endif /* HAVE_USR_INCLUDE_MALLOC_H */
   676 #endif /* NO_MALLINFO */
   677 
   678 #ifdef __cplusplus
   679 extern "C"
   680 {
   681 #endif                          /* __cplusplus */
   682 
   683 #if !ONLY_MSPACES
   684 
   685 /* ------------------- Declarations of public routines ------------------- */
   686 
   687 #ifndef USE_DL_PREFIX
   688 #define dlcalloc               calloc
   689 #define dlfree                 free
   690 #define dlmalloc               malloc
   691 #define dlmemalign             memalign
   692 #define dlrealloc              realloc
   693 #define dlvalloc               valloc
   694 #define dlpvalloc              pvalloc
   695 #define dlmallinfo             mallinfo
   696 #define dlmallopt              mallopt
   697 #define dlmalloc_trim          malloc_trim
   698 #define dlmalloc_stats         malloc_stats
   699 #define dlmalloc_usable_size   malloc_usable_size
   700 #define dlmalloc_footprint     malloc_footprint
   701 #define dlmalloc_max_footprint malloc_max_footprint
   702 #define dlindependent_calloc   independent_calloc
   703 #define dlindependent_comalloc independent_comalloc
   704 #endif                          /* USE_DL_PREFIX */
   705 
   706 
   707 /*
   708   malloc(size_t n)
   709   Returns a pointer to a newly allocated chunk of at least n bytes, or
   710   null if no space is available, in which case errno is set to ENOMEM
   711   on ANSI C systems.
   712 
   713   If n is zero, malloc returns a minimum-sized chunk. (The minimum
   714   size is 16 bytes on most 32bit systems, and 32 bytes on 64bit
   715   systems.)  Note that size_t is an unsigned type, so calls with
   716   arguments that would be negative if signed are interpreted as
   717   requests for huge amounts of space, which will often fail. The
   718   maximum supported value of n differs across systems, but is in all
   719   cases less than the maximum representable value of a size_t.
   720 */
   721     void *dlmalloc (size_t);
   722 
   723 /*
   724   free(void* p)
   725   Releases the chunk of memory pointed to by p, that had been previously
   726   allocated using malloc or a related routine such as realloc.
   727   It has no effect if p is null. If p was not malloced or already
   728   freed, free(p) will by default cause the current program to abort.
   729 */
   730     void dlfree (void *);
   731 
   732 /*
   733   calloc(size_t n_elements, size_t element_size);
   734   Returns a pointer to n_elements * element_size bytes, with all locations
   735   set to zero.
   736 */
   737     void *dlcalloc (size_t, size_t);
   738 
   739 /*
   740   realloc(void* p, size_t n)
   741   Returns a pointer to a chunk of size n that contains the same data
   742   as does chunk p up to the minimum of (n, p's size) bytes, or null
   743   if no space is available.
   744 
   745   The returned pointer may or may not be the same as p. The algorithm
   746   prefers extending p in most cases when possible, otherwise it
   747   employs the equivalent of a malloc-copy-free sequence.
   748 
   749   If p is null, realloc is equivalent to malloc.
   750 
   751   If space is not available, realloc returns null, errno is set (if on
   752   ANSI) and p is NOT freed.
   753 
   754   if n is for fewer bytes than already held by p, the newly unused
   755   space is lopped off and freed if possible.  realloc with a size
   756   argument of zero (re)allocates a minimum-sized chunk.
   757 
   758   The old unix realloc convention of allowing the last-free'd chunk
   759   to be used as an argument to realloc is not supported.
   760 */
   761 
   762     void *dlrealloc (void *, size_t);
   763 
   764 /*
   765   memalign(size_t alignment, size_t n);
   766   Returns a pointer to a newly allocated chunk of n bytes, aligned
   767   in accord with the alignment argument.
   768 
   769   The alignment argument should be a power of two. If the argument is
   770   not a power of two, the nearest greater power is used.
   771   8-byte alignment is guaranteed by normal malloc calls, so don't
   772   bother calling memalign with an argument of 8 or less.
   773 
   774   Overreliance on memalign is a sure way to fragment space.
   775 */
   776     void *dlmemalign (size_t, size_t);
   777 
   778 /*
   779   valloc(size_t n);
   780   Equivalent to memalign(pagesize, n), where pagesize is the page
   781   size of the system. If the pagesize is unknown, 4096 is used.
   782 */
   783     void *dlvalloc (size_t);
   784 
   785 /*
   786   mallopt(int parameter_number, int parameter_value)
   787   Sets tunable parameters The format is to provide a
   788   (parameter-number, parameter-value) pair.  mallopt then sets the
   789   corresponding parameter to the argument value if it can (i.e., so
   790   long as the value is meaningful), and returns 1 if successful else
   791   0.  SVID/XPG/ANSI defines four standard param numbers for mallopt,
   792   normally defined in malloc.h.  None of these are use in this malloc,
   793   so setting them has no effect. But this malloc also supports other
   794   options in mallopt. See below for details.  Briefly, supported
   795   parameters are as follows (listed defaults are for "typical"
   796   configurations).
   797 
   798   Symbol            param #  default    allowed param values
   799   M_TRIM_THRESHOLD     -1   2*1024*1024   any   (MAX_SIZE_T disables)
   800   M_GRANULARITY        -2     page size   any power of 2 >= page size
   801   M_MMAP_THRESHOLD     -3      256*1024   any   (or 0 if no MMAP support)
   802 */
   803     int dlmallopt (int, int);
   804 
   805 /*
   806   malloc_footprint();
   807   Returns the number of bytes obtained from the system.  The total
   808   number of bytes allocated by malloc, realloc etc., is less than this
   809   value. Unlike mallinfo, this function returns only a precomputed
   810   result, so can be called frequently to monitor memory consumption.
   811   Even if locks are otherwise defined, this function does not use them,
   812   so results might not be up to date.
   813 */
   814     size_t dlmalloc_footprint (void);
   815 
   816 /*
   817   malloc_max_footprint();
   818   Returns the maximum number of bytes obtained from the system. This
   819   value will be greater than current footprint if deallocated space
   820   has been reclaimed by the system. The peak number of bytes allocated
   821   by malloc, realloc etc., is less than this value. Unlike mallinfo,
   822   this function returns only a precomputed result, so can be called
   823   frequently to monitor memory consumption.  Even if locks are
   824   otherwise defined, this function does not use them, so results might
   825   not be up to date.
   826 */
   827     size_t dlmalloc_max_footprint (void);
   828 
   829 #if !NO_MALLINFO
   830 /*
   831   mallinfo()
   832   Returns (by copy) a struct containing various summary statistics:
   833 
   834   arena:     current total non-mmapped bytes allocated from system
   835   ordblks:   the number of free chunks
   836   smblks:    always zero.
   837   hblks:     current number of mmapped regions
   838   hblkhd:    total bytes held in mmapped regions
   839   usmblks:   the maximum total allocated space. This will be greater
   840                 than current total if trimming has occurred.
   841   fsmblks:   always zero
   842   uordblks:  current total allocated space (normal or mmapped)
   843   fordblks:  total free space
   844   keepcost:  the maximum number of bytes that could ideally be released
   845                back to system via malloc_trim. ("ideally" means that
   846                it ignores page restrictions etc.)
   847 
   848   Because these fields are ints, but internal bookkeeping may
   849   be kept as longs, the reported values may wrap around zero and
   850   thus be inaccurate.
   851 */
   852     struct mallinfo dlmallinfo (void);
   853 #endif                          /* NO_MALLINFO */
   854 
   855 /*
   856   independent_calloc(size_t n_elements, size_t element_size, void* chunks[]);
   857 
   858   independent_calloc is similar to calloc, but instead of returning a
   859   single cleared space, it returns an array of pointers to n_elements
   860   independent elements that can hold contents of size elem_size, each
   861   of which starts out cleared, and can be independently freed,
   862   realloc'ed etc. The elements are guaranteed to be adjacently
   863   allocated (this is not guaranteed to occur with multiple callocs or
   864   mallocs), which may also improve cache locality in some
   865   applications.
   866 
   867   The "chunks" argument is optional (i.e., may be null, which is
   868   probably the most typical usage). If it is null, the returned array
   869   is itself dynamically allocated and should also be freed when it is
   870   no longer needed. Otherwise, the chunks array must be of at least
   871   n_elements in length. It is filled in with the pointers to the
   872   chunks.
   873 
   874   In either case, independent_calloc returns this pointer array, or
   875   null if the allocation failed.  If n_elements is zero and "chunks"
   876   is null, it returns a chunk representing an array with zero elements
   877   (which should be freed if not wanted).
   878 
   879   Each element must be individually freed when it is no longer
   880   needed. If you'd like to instead be able to free all at once, you
   881   should instead use regular calloc and assign pointers into this
   882   space to represent elements.  (In this case though, you cannot
   883   independently free elements.)
   884 
   885   independent_calloc simplifies and speeds up implementations of many
   886   kinds of pools.  It may also be useful when constructing large data
   887   structures that initially have a fixed number of fixed-sized nodes,
   888   but the number is not known at compile time, and some of the nodes
   889   may later need to be freed. For example:
   890 
   891   struct Node { int item; struct Node* next; };
   892 
   893   struct Node* build_list() {
   894     struct Node** pool;
   895     int n = read_number_of_nodes_needed();
   896     if (n <= 0) return 0;
   897     pool = (struct Node**)(independent_calloc(n, sizeof(struct Node), 0);
   898     if (pool == 0) die();
   899     // organize into a linked list...
   900     struct Node* first = pool[0];
   901     for (i = 0; i < n-1; ++i)
   902       pool[i]->next = pool[i+1];
   903     free(pool);     // Can now free the array (or not, if it is needed later)
   904     return first;
   905   }
   906 */
   907     void **dlindependent_calloc (size_t, size_t, void **);
   908 
   909 /*
   910   independent_comalloc(size_t n_elements, size_t sizes[], void* chunks[]);
   911 
   912   independent_comalloc allocates, all at once, a set of n_elements
   913   chunks with sizes indicated in the "sizes" array.    It returns
   914   an array of pointers to these elements, each of which can be
   915   independently freed, realloc'ed etc. The elements are guaranteed to
   916   be adjacently allocated (this is not guaranteed to occur with
   917   multiple callocs or mallocs), which may also improve cache locality
   918   in some applications.
   919 
   920   The "chunks" argument is optional (i.e., may be null). If it is null
   921   the returned array is itself dynamically allocated and should also
   922   be freed when it is no longer needed. Otherwise, the chunks array
   923   must be of at least n_elements in length. It is filled in with the
   924   pointers to the chunks.
   925 
   926   In either case, independent_comalloc returns this pointer array, or
   927   null if the allocation failed.  If n_elements is zero and chunks is
   928   null, it returns a chunk representing an array with zero elements
   929   (which should be freed if not wanted).
   930 
   931   Each element must be individually freed when it is no longer
   932   needed. If you'd like to instead be able to free all at once, you
   933   should instead use a single regular malloc, and assign pointers at
   934   particular offsets in the aggregate space. (In this case though, you
   935   cannot independently free elements.)
   936 
   937   independent_comallac differs from independent_calloc in that each
   938   element may have a different size, and also that it does not
   939   automatically clear elements.
   940 
   941   independent_comalloc can be used to speed up allocation in cases
   942   where several structs or objects must always be allocated at the
   943   same time.  For example:
   944 
   945   struct Head { ... }
   946   struct Foot { ... }
   947 
   948   void send_message(char* msg) {
   949     int msglen = strlen(msg);
   950     size_t sizes[3] = { sizeof(struct Head), msglen, sizeof(struct Foot) };
   951     void* chunks[3];
   952     if (independent_comalloc(3, sizes, chunks) == 0)
   953       die();
   954     struct Head* head = (struct Head*)(chunks[0]);
   955     char*        body = (char*)(chunks[1]);
   956     struct Foot* foot = (struct Foot*)(chunks[2]);
   957     // ...
   958   }
   959 
   960   In general though, independent_comalloc is worth using only for
   961   larger values of n_elements. For small values, you probably won't
   962   detect enough difference from series of malloc calls to bother.
   963 
   964   Overuse of independent_comalloc can increase overall memory usage,
   965   since it cannot reuse existing noncontiguous small chunks that
   966   might be available for some of the elements.
   967 */
   968     void **dlindependent_comalloc (size_t, size_t *, void **);
   969 
   970 
   971 /*
   972   pvalloc(size_t n);
   973   Equivalent to valloc(minimum-page-that-holds(n)), that is,
   974   round up n to nearest pagesize.
   975  */
   976     void *dlpvalloc (size_t);
   977 
   978 /*
   979   malloc_trim(size_t pad);
   980 
   981   If possible, gives memory back to the system (via negative arguments
   982   to sbrk) if there is unused memory at the `high' end of the malloc
   983   pool or in unused MMAP segments. You can call this after freeing
   984   large blocks of memory to potentially reduce the system-level memory
   985   requirements of a program. However, it cannot guarantee to reduce
   986   memory. Under some allocation patterns, some large free blocks of
   987   memory will be locked between two used chunks, so they cannot be
   988   given back to the system.
   989 
   990   The `pad' argument to malloc_trim represents the amount of free
   991   trailing space to leave untrimmed. If this argument is zero, only
   992   the minimum amount of memory to maintain internal data structures
   993   will be left. Non-zero arguments can be supplied to maintain enough
   994   trailing space to service future expected allocations without having
   995   to re-obtain memory from the system.
   996 
   997   Malloc_trim returns 1 if it actually released any memory, else 0.
   998 */
   999     int dlmalloc_trim (size_t);
  1000 
  1001 /*
  1002   malloc_usable_size(void* p);
  1003 
  1004   Returns the number of bytes you can actually use in
  1005   an allocated chunk, which may be more than you requested (although
  1006   often not) due to alignment and minimum size constraints.
  1007   You can use this many bytes without worrying about
  1008   overwriting other allocated objects. This is not a particularly great
  1009   programming practice. malloc_usable_size can be more useful in
  1010   debugging and assertions, for example:
  1011 
  1012   p = malloc(n);
  1013   assert(malloc_usable_size(p) >= 256);
  1014 */
  1015     size_t dlmalloc_usable_size (void *);
  1016 
  1017 /*
  1018   malloc_stats();
  1019   Prints on stderr the amount of space obtained from the system (both
  1020   via sbrk and mmap), the maximum amount (which may be more than
  1021   current if malloc_trim and/or munmap got called), and the current
  1022   number of bytes allocated via malloc (or realloc, etc) but not yet
  1023   freed. Note that this is the number of bytes allocated, not the
  1024   number requested. It will be larger than the number requested
  1025   because of alignment and bookkeeping overhead. Because it includes
  1026   alignment wastage as being in use, this figure may be greater than
  1027   zero even when no user-level chunks are allocated.
  1028 
  1029   The reported current and maximum system memory can be inaccurate if
  1030   a program makes other calls to system memory allocation functions
  1031   (normally sbrk) outside of malloc.
  1032 
  1033   malloc_stats prints only the most commonly interesting statistics.
  1034   More information can be obtained by calling mallinfo.
  1035 */
  1036     void dlmalloc_stats (void);
  1037 
  1038 #endif                          /* ONLY_MSPACES */
  1039 
  1040 #if MSPACES
  1041 
  1042 /*
  1043   mspace is an opaque type representing an independent
  1044   region of space that supports mspace_malloc, etc.
  1045 */
  1046     typedef void *mspace;
  1047 
  1048 /*
  1049   create_mspace creates and returns a new independent space with the
  1050   given initial capacity, or, if 0, the default granularity size.  It
  1051   returns null if there is no system memory available to create the
  1052   space.  If argument locked is non-zero, the space uses a separate
  1053   lock to control access. The capacity of the space will grow
  1054   dynamically as needed to service mspace_malloc requests.  You can
  1055   control the sizes of incremental increases of this space by
  1056   compiling with a different DEFAULT_GRANULARITY or dynamically
  1057   setting with mallopt(M_GRANULARITY, value).
  1058 */
  1059     mspace create_mspace (size_t capacity, int locked);
  1060 
  1061 /*
  1062   destroy_mspace destroys the given space, and attempts to return all
  1063   of its memory back to the system, returning the total number of
  1064   bytes freed. After destruction, the results of access to all memory
  1065   used by the space become undefined.
  1066 */
  1067     size_t destroy_mspace (mspace msp);
  1068 
  1069 /*
  1070   create_mspace_with_base uses the memory supplied as the initial base
  1071   of a new mspace. Part (less than 128*sizeof(size_t) bytes) of this
  1072   space is used for bookkeeping, so the capacity must be at least this
  1073   large. (Otherwise 0 is returned.) When this initial space is
  1074   exhausted, additional memory will be obtained from the system.
  1075   Destroying this space will deallocate all additionally allocated
  1076   space (if possible) but not the initial base.
  1077 */
  1078     mspace create_mspace_with_base (void *base, size_t capacity, int locked);
  1079 
  1080 /*
  1081   mspace_malloc behaves as malloc, but operates within
  1082   the given space.
  1083 */
  1084     void *mspace_malloc (mspace msp, size_t bytes);
  1085 
  1086 /*
  1087   mspace_free behaves as free, but operates within
  1088   the given space.
  1089 
  1090   If compiled with FOOTERS==1, mspace_free is not actually needed.
  1091   free may be called instead of mspace_free because freed chunks from
  1092   any space are handled by their originating spaces.
  1093 */
  1094     void mspace_free (mspace msp, void *mem);
  1095 
  1096 /*
  1097   mspace_realloc behaves as realloc, but operates within
  1098   the given space.
  1099 
  1100   If compiled with FOOTERS==1, mspace_realloc is not actually
  1101   needed.  realloc may be called instead of mspace_realloc because
  1102   realloced chunks from any space are handled by their originating
  1103   spaces.
  1104 */
  1105     void *mspace_realloc (mspace msp, void *mem, size_t newsize);
  1106 
  1107 /*
  1108   mspace_calloc behaves as calloc, but operates within
  1109   the given space.
  1110 */
  1111     void *mspace_calloc (mspace msp, size_t n_elements, size_t elem_size);
  1112 
  1113 /*
  1114   mspace_memalign behaves as memalign, but operates within
  1115   the given space.
  1116 */
  1117     void *mspace_memalign (mspace msp, size_t alignment, size_t bytes);
  1118 
  1119 /*
  1120   mspace_independent_calloc behaves as independent_calloc, but
  1121   operates within the given space.
  1122 */
  1123     void **mspace_independent_calloc (mspace msp, size_t n_elements,
  1124                                       size_t elem_size, void *chunks[]);
  1125 
  1126 /*
  1127   mspace_independent_comalloc behaves as independent_comalloc, but
  1128   operates within the given space.
  1129 */
  1130     void **mspace_independent_comalloc (mspace msp, size_t n_elements,
  1131                                         size_t sizes[], void *chunks[]);
  1132 
  1133 /*
  1134   mspace_footprint() returns the number of bytes obtained from the
  1135   system for this space.
  1136 */
  1137     size_t mspace_footprint (mspace msp);
  1138 
  1139 /*
  1140   mspace_max_footprint() returns the peak number of bytes obtained from the
  1141   system for this space.
  1142 */
  1143     size_t mspace_max_footprint (mspace msp);
  1144 
  1145 
  1146 #if !NO_MALLINFO
  1147 /*
  1148   mspace_mallinfo behaves as mallinfo, but reports properties of
  1149   the given space.
  1150 */
  1151     struct mallinfo mspace_mallinfo (mspace msp);
  1152 #endif                          /* NO_MALLINFO */
  1153 
  1154 /*
  1155   mspace_malloc_stats behaves as malloc_stats, but reports
  1156   properties of the given space.
  1157 */
  1158     void mspace_malloc_stats (mspace msp);
  1159 
  1160 /*
  1161   mspace_trim behaves as malloc_trim, but
  1162   operates within the given space.
  1163 */
  1164     int mspace_trim (mspace msp, size_t pad);
  1165 
  1166 /*
  1167   An alias for mallopt.
  1168 */
  1169     int mspace_mallopt (int, int);
  1170 
  1171 #endif                          /* MSPACES */
  1172 
  1173 #ifdef __cplusplus
  1174 };                              /* end of extern "C" */
  1175 #endif /* __cplusplus */
  1176 
  1177 /*
  1178   ========================================================================
  1179   To make a fully customizable malloc.h header file, cut everything
  1180   above this line, put into file malloc.h, edit to suit, and #include it
  1181   on the next line, as well as in programs that use this malloc.
  1182   ========================================================================
  1183 */
  1184 
  1185 /* #include "malloc.h" */
  1186 
  1187 /*------------------------------ internal #includes ---------------------- */
  1188 
  1189 #ifdef _MSC_VER
  1190 #pragma warning( disable : 4146 )       /* no "unsigned" warnings */
  1191 #endif /* _MSC_VER */
  1192 
  1193 #ifndef LACKS_STDIO_H
  1194 #include <stdio.h>              /* for printing in malloc_stats */
  1195 #endif
  1196 
  1197 #ifndef LACKS_ERRNO_H
  1198 #include <errno.h>              /* for MALLOC_FAILURE_ACTION */
  1199 #endif /* LACKS_ERRNO_H */
  1200 #if FOOTERS
  1201 #include <time.h>               /* for magic initialization */
  1202 #endif /* FOOTERS */
  1203 #ifndef LACKS_STDLIB_H
  1204 #include <stdlib.h>             /* for abort() */
  1205 #endif /* LACKS_STDLIB_H */
  1206 #ifdef DEBUG
  1207 #if ABORT_ON_ASSERT_FAILURE
  1208 #define assert(x) if(!(x)) ABORT
  1209 #else /* ABORT_ON_ASSERT_FAILURE */
  1210 #include <assert.h>
  1211 #endif /* ABORT_ON_ASSERT_FAILURE */
  1212 #else /* DEBUG */
  1213 #define assert(x)
  1214 #endif /* DEBUG */
  1215 #ifndef LACKS_STRING_H
  1216 #include <string.h>             /* for memset etc */
  1217 #endif /* LACKS_STRING_H */
  1218 #if USE_BUILTIN_FFS
  1219 #ifndef LACKS_STRINGS_H
  1220 #include <strings.h>            /* for ffs */
  1221 #endif /* LACKS_STRINGS_H */
  1222 #endif /* USE_BUILTIN_FFS */
  1223 #if HAVE_MMAP
  1224 #ifndef LACKS_SYS_MMAN_H
  1225 #include <sys/mman.h>           /* for mmap */
  1226 #endif /* LACKS_SYS_MMAN_H */
  1227 #ifndef LACKS_FCNTL_H
  1228 #include <fcntl.h>
  1229 #endif /* LACKS_FCNTL_H */
  1230 #endif /* HAVE_MMAP */
  1231 #if HAVE_MORECORE
  1232 #ifndef LACKS_UNISTD_H
  1233 #include <unistd.h>             /* for sbrk */
  1234 #else /* LACKS_UNISTD_H */
  1235 #if !defined(__FreeBSD__) && !defined(__OpenBSD__) && !defined(__NetBSD__)
  1236 extern void *sbrk (ptrdiff_t);
  1237 #endif /* FreeBSD etc */
  1238 #endif /* LACKS_UNISTD_H */
  1239 #endif /* HAVE_MMAP */
  1240 
  1241 #ifndef WIN32
  1242 #ifndef malloc_getpagesize
  1243 #  ifdef _SC_PAGESIZE           /* some SVR4 systems omit an underscore */
  1244 #    ifndef _SC_PAGE_SIZE
  1245 #      define _SC_PAGE_SIZE _SC_PAGESIZE
  1246 #    endif
  1247 #  endif
  1248 #  ifdef _SC_PAGE_SIZE
  1249 #    define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
  1250 #  else
  1251 #    if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
  1252 extern size_t getpagesize ();
  1253 #      define malloc_getpagesize getpagesize()
  1254 #    else
  1255 #      ifdef WIN32              /* use supplied emulation of getpagesize */
  1256 #        define malloc_getpagesize getpagesize()
  1257 #      else
  1258 #        ifndef LACKS_SYS_PARAM_H
  1259 #          include <sys/param.h>
  1260 #        endif
  1261 #        ifdef EXEC_PAGESIZE
  1262 #          define malloc_getpagesize EXEC_PAGESIZE
  1263 #        else
  1264 #          ifdef NBPG
  1265 #            ifndef CLSIZE
  1266 #              define malloc_getpagesize NBPG
  1267 #            else
  1268 #              define malloc_getpagesize (NBPG * CLSIZE)
  1269 #            endif
  1270 #          else
  1271 #            ifdef NBPC
  1272 #              define malloc_getpagesize NBPC
  1273 #            else
  1274 #              ifdef PAGESIZE
  1275 #                define malloc_getpagesize PAGESIZE
  1276 #              else /* just guess */
  1277 #                define malloc_getpagesize ((size_t)4096U)
  1278 #              endif
  1279 #            endif
  1280 #          endif
  1281 #        endif
  1282 #      endif
  1283 #    endif
  1284 #  endif
  1285 #endif
  1286 #endif
  1287 
  1288 /* ------------------- size_t and alignment properties -------------------- */
  1289 
  1290 /* The byte and bit size of a size_t */
  1291 #define SIZE_T_SIZE         (sizeof(size_t))
  1292 #define SIZE_T_BITSIZE      (sizeof(size_t) << 3)
  1293 
  1294 /* Some constants coerced to size_t */
  1295 /* Annoying but necessary to avoid errors on some plaftorms */
  1296 #define SIZE_T_ZERO         ((size_t)0)
  1297 #define SIZE_T_ONE          ((size_t)1)
  1298 #define SIZE_T_TWO          ((size_t)2)
  1299 #define TWO_SIZE_T_SIZES    (SIZE_T_SIZE<<1)
  1300 #define FOUR_SIZE_T_SIZES   (SIZE_T_SIZE<<2)
  1301 #define SIX_SIZE_T_SIZES    (FOUR_SIZE_T_SIZES+TWO_SIZE_T_SIZES)
  1302 #define HALF_MAX_SIZE_T     (MAX_SIZE_T / 2U)
  1303 
  1304 /* The bit mask value corresponding to MALLOC_ALIGNMENT */
  1305 #define CHUNK_ALIGN_MASK    (MALLOC_ALIGNMENT - SIZE_T_ONE)
  1306 
  1307 /* True if address a has acceptable alignment */
  1308 #define is_aligned(A)       (((size_t)((A)) & (CHUNK_ALIGN_MASK)) == 0)
  1309 
  1310 /* the number of bytes to offset an address to align it */
  1311 #define align_offset(A)\
  1312  ((((size_t)(A) & CHUNK_ALIGN_MASK) == 0)? 0 :\
  1313   ((MALLOC_ALIGNMENT - ((size_t)(A) & CHUNK_ALIGN_MASK)) & CHUNK_ALIGN_MASK))
  1314 
  1315 /* -------------------------- MMAP preliminaries ------------------------- */
  1316 
  1317 /*
  1318    If HAVE_MORECORE or HAVE_MMAP are false, we just define calls and
  1319    checks to fail so compiler optimizer can delete code rather than
  1320    using so many "#if"s.
  1321 */
  1322 
  1323 
  1324 /* MORECORE and MMAP must return MFAIL on failure */
  1325 #define MFAIL                ((void*)(MAX_SIZE_T))
  1326 #define CMFAIL               ((char*)(MFAIL))   /* defined for convenience */
  1327 
  1328 #if !HAVE_MMAP
  1329 #define IS_MMAPPED_BIT       (SIZE_T_ZERO)
  1330 #define USE_MMAP_BIT         (SIZE_T_ZERO)
  1331 #define CALL_MMAP(s)         MFAIL
  1332 #define CALL_MUNMAP(a, s)    (-1)
  1333 #define DIRECT_MMAP(s)       MFAIL
  1334 
  1335 #else /* HAVE_MMAP */
  1336 #define IS_MMAPPED_BIT       (SIZE_T_ONE)
  1337 #define USE_MMAP_BIT         (SIZE_T_ONE)
  1338 
  1339 #ifndef WIN32
  1340 #define CALL_MUNMAP(a, s)    munmap((a), (s))
  1341 #define MMAP_PROT            (PROT_READ|PROT_WRITE)
  1342 #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
  1343 #define MAP_ANONYMOUS        MAP_ANON
  1344 #endif /* MAP_ANON */
  1345 #ifdef MAP_ANONYMOUS
  1346 #define MMAP_FLAGS           (MAP_PRIVATE|MAP_ANONYMOUS)
  1347 #define CALL_MMAP(s)         mmap(0, (s), MMAP_PROT, MMAP_FLAGS, -1, 0)
  1348 #else /* MAP_ANONYMOUS */
  1349 /*
  1350    Nearly all versions of mmap support MAP_ANONYMOUS, so the following
  1351    is unlikely to be needed, but is supplied just in case.
  1352 */
  1353 #define MMAP_FLAGS           (MAP_PRIVATE)
  1354 static int dev_zero_fd = -1;    /* Cached file descriptor for /dev/zero. */
  1355 #define CALL_MMAP(s) ((dev_zero_fd < 0) ? \
  1356            (dev_zero_fd = open("/dev/zero", O_RDWR), \
  1357             mmap(0, (s), MMAP_PROT, MMAP_FLAGS, dev_zero_fd, 0)) : \
  1358             mmap(0, (s), MMAP_PROT, MMAP_FLAGS, dev_zero_fd, 0))
  1359 #endif /* MAP_ANONYMOUS */
  1360 
  1361 #define DIRECT_MMAP(s)       CALL_MMAP(s)
  1362 #else /* WIN32 */
  1363 
  1364 /* Win32 MMAP via VirtualAlloc */
  1365 static void *
  1366 win32mmap (size_t size)
  1367 {
  1368     void *ptr =
  1369         VirtualAlloc (0, size, MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
  1370     return (ptr != 0) ? ptr : MFAIL;
  1371 }
  1372 
  1373 /* For direct MMAP, use MEM_TOP_DOWN to minimize interference */
  1374 static void *
  1375 win32direct_mmap (size_t size)
  1376 {
  1377     void *ptr =
  1378         VirtualAlloc (0, size, MEM_RESERVE | MEM_COMMIT | MEM_TOP_DOWN,
  1379                       PAGE_READWRITE);
  1380     return (ptr != 0) ? ptr : MFAIL;
  1381 }
  1382 
  1383 /* This function supports releasing coalesed segments */
  1384 static int
  1385 win32munmap (void *ptr, size_t size)
  1386 {
  1387     MEMORY_BASIC_INFORMATION minfo;
  1388     char *cptr = ptr;
  1389     while (size) {
  1390         if (VirtualQuery (cptr, &minfo, sizeof (minfo)) == 0)
  1391             return -1;
  1392         if (minfo.BaseAddress != cptr || minfo.AllocationBase != cptr ||
  1393             minfo.State != MEM_COMMIT || minfo.RegionSize > size)
  1394             return -1;
  1395         if (VirtualFree (cptr, 0, MEM_RELEASE) == 0)
  1396             return -1;
  1397         cptr += minfo.RegionSize;
  1398         size -= minfo.RegionSize;
  1399     }
  1400     return 0;
  1401 }
  1402 
  1403 #define CALL_MMAP(s)         win32mmap(s)
  1404 #define CALL_MUNMAP(a, s)    win32munmap((a), (s))
  1405 #define DIRECT_MMAP(s)       win32direct_mmap(s)
  1406 #endif /* WIN32 */
  1407 #endif /* HAVE_MMAP */
  1408 
  1409 #if HAVE_MMAP && HAVE_MREMAP
  1410 #define CALL_MREMAP(addr, osz, nsz, mv) mremap((addr), (osz), (nsz), (mv))
  1411 #else /* HAVE_MMAP && HAVE_MREMAP */
  1412 #define CALL_MREMAP(addr, osz, nsz, mv) MFAIL
  1413 #endif /* HAVE_MMAP && HAVE_MREMAP */
  1414 
  1415 #if HAVE_MORECORE
  1416 #define CALL_MORECORE(S)     MORECORE(S)
  1417 #else /* HAVE_MORECORE */
  1418 #define CALL_MORECORE(S)     MFAIL
  1419 #endif /* HAVE_MORECORE */
  1420 
  1421 /* mstate bit set if continguous morecore disabled or failed */
  1422 #define USE_NONCONTIGUOUS_BIT (4U)
  1423 
  1424 /* segment bit set in create_mspace_with_base */
  1425 #define EXTERN_BIT            (8U)
  1426 
  1427 
  1428 /* --------------------------- Lock preliminaries ------------------------ */
  1429 
  1430 #if USE_LOCKS
  1431 
  1432 /*
  1433   When locks are defined, there are up to two global locks:
  1434 
  1435   * If HAVE_MORECORE, morecore_mutex protects sequences of calls to
  1436     MORECORE.  In many cases sys_alloc requires two calls, that should
  1437     not be interleaved with calls by other threads.  This does not
  1438     protect against direct calls to MORECORE by other threads not
  1439     using this lock, so there is still code to cope the best we can on
  1440     interference.
  1441 
  1442   * magic_init_mutex ensures that mparams.magic and other
  1443     unique mparams values are initialized only once.
  1444 */
  1445 
  1446 #ifndef WIN32
  1447 /* By default use posix locks */
  1448 #include <pthread.h>
  1449 #define MLOCK_T pthread_mutex_t
  1450 #define INITIAL_LOCK(l)      pthread_mutex_init(l, NULL)
  1451 #define ACQUIRE_LOCK(l)      pthread_mutex_lock(l)
  1452 #define RELEASE_LOCK(l)      pthread_mutex_unlock(l)
  1453 
  1454 #if HAVE_MORECORE
  1455 static MLOCK_T morecore_mutex = PTHREAD_MUTEX_INITIALIZER;
  1456 #endif /* HAVE_MORECORE */
  1457 
  1458 static MLOCK_T magic_init_mutex = PTHREAD_MUTEX_INITIALIZER;
  1459 
  1460 #else /* WIN32 */
  1461 /*
  1462    Because lock-protected regions have bounded times, and there
  1463    are no recursive lock calls, we can use simple spinlocks.
  1464 */
  1465 
  1466 #define MLOCK_T long
  1467 static int
  1468 win32_acquire_lock (MLOCK_T * sl)
  1469 {
  1470     for (;;) {
  1471 #ifdef InterlockedCompareExchangePointer
  1472         if (!InterlockedCompareExchange (sl, 1, 0))
  1473             return 0;
  1474 #else /* Use older void* version */
  1475         if (!InterlockedCompareExchange
  1476             ((void **) sl, (void *) 1, (void *) 0))
  1477             return 0;
  1478 #endif /* InterlockedCompareExchangePointer */
  1479         Sleep (0);
  1480     }
  1481 }
  1482 
  1483 static void
  1484 win32_release_lock (MLOCK_T * sl)
  1485 {
  1486     InterlockedExchange (sl, 0);
  1487 }
  1488 
  1489 #define INITIAL_LOCK(l)      *(l)=0
  1490 #define ACQUIRE_LOCK(l)      win32_acquire_lock(l)
  1491 #define RELEASE_LOCK(l)      win32_release_lock(l)
  1492 #if HAVE_MORECORE
  1493 static MLOCK_T morecore_mutex;
  1494 #endif /* HAVE_MORECORE */
  1495 static MLOCK_T magic_init_mutex;
  1496 #endif /* WIN32 */
  1497 
  1498 #define USE_LOCK_BIT               (2U)
  1499 #else /* USE_LOCKS */
  1500 #define USE_LOCK_BIT               (0U)
  1501 #define INITIAL_LOCK(l)
  1502 #endif /* USE_LOCKS */
  1503 
  1504 #if USE_LOCKS && HAVE_MORECORE
  1505 #define ACQUIRE_MORECORE_LOCK()    ACQUIRE_LOCK(&morecore_mutex);
  1506 #define RELEASE_MORECORE_LOCK()    RELEASE_LOCK(&morecore_mutex);
  1507 #else /* USE_LOCKS && HAVE_MORECORE */
  1508 #define ACQUIRE_MORECORE_LOCK()
  1509 #define RELEASE_MORECORE_LOCK()
  1510 #endif /* USE_LOCKS && HAVE_MORECORE */
  1511 
  1512 #if USE_LOCKS
  1513 #define ACQUIRE_MAGIC_INIT_LOCK()  ACQUIRE_LOCK(&magic_init_mutex);
  1514 #define RELEASE_MAGIC_INIT_LOCK()  RELEASE_LOCK(&magic_init_mutex);
  1515 #else /* USE_LOCKS */
  1516 #define ACQUIRE_MAGIC_INIT_LOCK()
  1517 #define RELEASE_MAGIC_INIT_LOCK()
  1518 #endif /* USE_LOCKS */
  1519 
  1520 
  1521 /* -----------------------  Chunk representations ------------------------ */
  1522 
  1523 /*
  1524   (The following includes lightly edited explanations by Colin Plumb.)
  1525 
  1526   The malloc_chunk declaration below is misleading (but accurate and
  1527   necessary).  It declares a "view" into memory allowing access to
  1528   necessary fields at known offsets from a given base.
  1529 
  1530   Chunks of memory are maintained using a `boundary tag' method as
  1531   originally described by Knuth.  (See the paper by Paul Wilson
  1532   ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a survey of such
  1533   techniques.)  Sizes of free chunks are stored both in the front of
  1534   each chunk and at the end.  This makes consolidating fragmented
  1535   chunks into bigger chunks fast.  The head fields also hold bits
  1536   representing whether chunks are free or in use.
  1537 
  1538   Here are some pictures to make it clearer.  They are "exploded" to
  1539   show that the state of a chunk can be thought of as extending from
  1540   the high 31 bits of the head field of its header through the
  1541   prev_foot and PINUSE_BIT bit of the following chunk header.
  1542 
  1543   A chunk that's in use looks like:
  1544 
  1545    chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1546            | Size of previous chunk (if P = 1)                             |
  1547            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1548          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |P|
  1549          | Size of this chunk                                         1| +-+
  1550    mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1551          |                                                               |
  1552          +-                                                             -+
  1553          |                                                               |
  1554          +-                                                             -+
  1555          |                                                               :
  1556          +-      size - sizeof(size_t) available payload bytes          -+
  1557          :                                                               |
  1558  chunk-> +-                                                             -+
  1559          |                                                               |
  1560          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1561        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|
  1562        | Size of next chunk (may or may not be in use)               | +-+
  1563  mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1564 
  1565     And if it's free, it looks like this:
  1566 
  1567    chunk-> +-                                                             -+
  1568            | User payload (must be in use, or we would have merged!)       |
  1569            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1570          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |P|
  1571          | Size of this chunk                                         0| +-+
  1572    mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1573          | Next pointer                                                  |
  1574          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1575          | Prev pointer                                                  |
  1576          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1577          |                                                               :
  1578          +-      size - sizeof(struct chunk) unused bytes               -+
  1579          :                                                               |
  1580  chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1581          | Size of this chunk                                            |
  1582          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1583        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0|
  1584        | Size of next chunk (must be in use, or we would have merged)| +-+
  1585  mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1586        |                                                               :
  1587        +- User payload                                                -+
  1588        :                                                               |
  1589        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1590                                                                      |0|
  1591                                                                      +-+
  1592   Note that since we always merge adjacent free chunks, the chunks
  1593   adjacent to a free chunk must be in use.
  1594 
  1595   Given a pointer to a chunk (which can be derived trivially from the
  1596   payload pointer) we can, in O(1) time, find out whether the adjacent
  1597   chunks are free, and if so, unlink them from the lists that they
  1598   are on and merge them with the current chunk.
  1599 
  1600   Chunks always begin on even word boundaries, so the mem portion
  1601   (which is returned to the user) is also on an even word boundary, and
  1602   thus at least double-word aligned.
  1603 
  1604   The P (PINUSE_BIT) bit, stored in the unused low-order bit of the
  1605   chunk size (which is always a multiple of two words), is an in-use
  1606   bit for the *previous* chunk.  If that bit is *clear*, then the
  1607   word before the current chunk size contains the previous chunk
  1608   size, and can be used to find the front of the previous chunk.
  1609   The very first chunk allocated always has this bit set, preventing
  1610   access to non-existent (or non-owned) memory. If pinuse is set for
  1611   any given chunk, then you CANNOT determine the size of the
  1612   previous chunk, and might even get a memory addressing fault when
  1613   trying to do so.
  1614 
  1615   The C (CINUSE_BIT) bit, stored in the unused second-lowest bit of
  1616   the chunk size redundantly records whether the current chunk is
  1617   inuse. This redundancy enables usage checks within free and realloc,
  1618   and reduces indirection when freeing and consolidating chunks.
  1619 
  1620   Each freshly allocated chunk must have both cinuse and pinuse set.
  1621   That is, each allocated chunk borders either a previously allocated
  1622   and still in-use chunk, or the base of its memory arena. This is
  1623   ensured by making all allocations from the the `lowest' part of any
  1624   found chunk.  Further, no free chunk physically borders another one,
  1625   so each free chunk is known to be preceded and followed by either
  1626   inuse chunks or the ends of memory.
  1627 
  1628   Note that the `foot' of the current chunk is actually represented
  1629   as the prev_foot of the NEXT chunk. This makes it easier to
  1630   deal with alignments etc but can be very confusing when trying
  1631   to extend or adapt this code.
  1632 
  1633   The exceptions to all this are
  1634 
  1635      1. The special chunk `top' is the top-most available chunk (i.e.,
  1636         the one bordering the end of available memory). It is treated
  1637         specially.  Top is never included in any bin, is used only if
  1638         no other chunk is available, and is released back to the
  1639         system if it is very large (see M_TRIM_THRESHOLD).  In effect,
  1640         the top chunk is treated as larger (and thus less well
  1641         fitting) than any other available chunk.  The top chunk
  1642         doesn't update its trailing size field since there is no next
  1643         contiguous chunk that would have to index off it. However,
  1644         space is still allocated for it (TOP_FOOT_SIZE) to enable
  1645         separation or merging when space is extended.
  1646 
  1647      3. Chunks allocated via mmap, which have the lowest-order bit
  1648         (IS_MMAPPED_BIT) set in their prev_foot fields, and do not set
  1649         PINUSE_BIT in their head fields.  Because they are allocated
  1650         one-by-one, each must carry its own prev_foot field, which is
  1651         also used to hold the offset this chunk has within its mmapped
  1652         region, which is needed to preserve alignment. Each mmapped
  1653         chunk is trailed by the first two fields of a fake next-chunk
  1654         for sake of usage checks.
  1655 
  1656 */
  1657 
  1658 struct malloc_chunk
  1659 {
  1660     size_t prev_foot;           /* Size of previous chunk (if free).  */
  1661     size_t head;                /* Size and inuse bits. */
  1662     struct malloc_chunk *fd;    /* double links -- used only if free. */
  1663     struct malloc_chunk *bk;
  1664 };
  1665 
  1666 typedef struct malloc_chunk mchunk;
  1667 typedef struct malloc_chunk *mchunkptr;
  1668 typedef struct malloc_chunk *sbinptr;   /* The type of bins of chunks */
  1669 typedef size_t bindex_t;        /* Described below */
  1670 typedef unsigned int binmap_t;  /* Described below */
  1671 typedef unsigned int flag_t;    /* The type of various bit flag sets */
  1672 
  1673 /* ------------------- Chunks sizes and alignments ----------------------- */
  1674 
  1675 #define MCHUNK_SIZE         (sizeof(mchunk))
  1676 
  1677 #if FOOTERS
  1678 #define CHUNK_OVERHEAD      (TWO_SIZE_T_SIZES)
  1679 #else /* FOOTERS */
  1680 #define CHUNK_OVERHEAD      (SIZE_T_SIZE)
  1681 #endif /* FOOTERS */
  1682 
  1683 /* MMapped chunks need a second word of overhead ... */
  1684 #define MMAP_CHUNK_OVERHEAD (TWO_SIZE_T_SIZES)
  1685 /* ... and additional padding for fake next-chunk at foot */
  1686 #define MMAP_FOOT_PAD       (FOUR_SIZE_T_SIZES)
  1687 
  1688 /* The smallest size we can malloc is an aligned minimal chunk */
  1689 #define MIN_CHUNK_SIZE\
  1690   ((MCHUNK_SIZE + CHUNK_ALIGN_MASK) & ~CHUNK_ALIGN_MASK)
  1691 
  1692 /* conversion from malloc headers to user pointers, and back */
  1693 #define chunk2mem(p)        ((void*)((char*)(p)       + TWO_SIZE_T_SIZES))
  1694 #define mem2chunk(mem)      ((mchunkptr)((char*)(mem) - TWO_SIZE_T_SIZES))
  1695 /* chunk associated with aligned address A */
  1696 #define align_as_chunk(A)   (mchunkptr)((A) + align_offset(chunk2mem(A)))
  1697 
  1698 /* Bounds on request (not chunk) sizes. */
  1699 #define MAX_REQUEST         ((-MIN_CHUNK_SIZE) << 2)
  1700 #define MIN_REQUEST         (MIN_CHUNK_SIZE - CHUNK_OVERHEAD - SIZE_T_ONE)
  1701 
  1702 /* pad request bytes into a usable size */
  1703 #define pad_request(req) \
  1704    (((req) + CHUNK_OVERHEAD + CHUNK_ALIGN_MASK) & ~CHUNK_ALIGN_MASK)
  1705 
  1706 /* pad request, checking for minimum (but not maximum) */
  1707 #define request2size(req) \
  1708   (((req) < MIN_REQUEST)? MIN_CHUNK_SIZE : pad_request(req))
  1709 
  1710 
  1711 /* ------------------ Operations on head and foot fields ----------------- */
  1712 
  1713 /*
  1714   The head field of a chunk is or'ed with PINUSE_BIT when previous
  1715   adjacent chunk in use, and or'ed with CINUSE_BIT if this chunk is in
  1716   use. If the chunk was obtained with mmap, the prev_foot field has
  1717   IS_MMAPPED_BIT set, otherwise holding the offset of the base of the
  1718   mmapped region to the base of the chunk.
  1719 */
  1720 
  1721 #define PINUSE_BIT          (SIZE_T_ONE)
  1722 #define CINUSE_BIT          (SIZE_T_TWO)
  1723 #define INUSE_BITS          (PINUSE_BIT|CINUSE_BIT)
  1724 
  1725 /* Head value for fenceposts */
  1726 #define FENCEPOST_HEAD      (INUSE_BITS|SIZE_T_SIZE)
  1727 
  1728 /* extraction of fields from head words */
  1729 #define cinuse(p)           ((p)->head & CINUSE_BIT)
  1730 #define pinuse(p)           ((p)->head & PINUSE_BIT)
  1731 #define chunksize(p)        ((p)->head & ~(INUSE_BITS))
  1732 
  1733 #define clear_pinuse(p)     ((p)->head &= ~PINUSE_BIT)
  1734 #define clear_cinuse(p)     ((p)->head &= ~CINUSE_BIT)
  1735 
  1736 /* Treat space at ptr +/- offset as a chunk */
  1737 #define chunk_plus_offset(p, s)  ((mchunkptr)(((char*)(p)) + (s)))
  1738 #define chunk_minus_offset(p, s) ((mchunkptr)(((char*)(p)) - (s)))
  1739 
  1740 /* Ptr to next or previous physical malloc_chunk. */
  1741 #define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->head & ~INUSE_BITS)))
  1742 #define prev_chunk(p) ((mchunkptr)( ((char*)(p)) - ((p)->prev_foot) ))
  1743 
  1744 /* extract next chunk's pinuse bit */
  1745 #define next_pinuse(p)  ((next_chunk(p)->head) & PINUSE_BIT)
  1746 
  1747 /* Get/set size at footer */
  1748 #define get_foot(p, s)  (((mchunkptr)((char*)(p) + (s)))->prev_foot)
  1749 #define set_foot(p, s)  (((mchunkptr)((char*)(p) + (s)))->prev_foot = (s))
  1750 
  1751 /* Set size, pinuse bit, and foot */
  1752 #define set_size_and_pinuse_of_free_chunk(p, s)\
  1753   ((p)->head = (s|PINUSE_BIT), set_foot(p, s))
  1754 
  1755 /* Set size, pinuse bit, foot, and clear next pinuse */
  1756 #define set_free_with_pinuse(p, s, n)\
  1757   (clear_pinuse(n), set_size_and_pinuse_of_free_chunk(p, s))
  1758 
  1759 #define is_mmapped(p)\
  1760   (!((p)->head & PINUSE_BIT) && ((p)->prev_foot & IS_MMAPPED_BIT))
  1761 
  1762 /* Get the internal overhead associated with chunk p */
  1763 #define overhead_for(p)\
  1764  (is_mmapped(p)? MMAP_CHUNK_OVERHEAD : CHUNK_OVERHEAD)
  1765 
  1766 /* Return true if malloced space is not necessarily cleared */
  1767 #if MMAP_CLEARS
  1768 #define calloc_must_clear(p) (!is_mmapped(p))
  1769 #else /* MMAP_CLEARS */
  1770 #define calloc_must_clear(p) (1)
  1771 #endif /* MMAP_CLEARS */
  1772 
  1773 /* ---------------------- Overlaid data structures ----------------------- */
  1774 
  1775 /*
  1776   When chunks are not in use, they are treated as nodes of either
  1777   lists or trees.
  1778 
  1779   "Small"  chunks are stored in circular doubly-linked lists, and look
  1780   like this:
  1781 
  1782     chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1783             |             Size of previous chunk                            |
  1784             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1785     `head:' |             Size of chunk, in bytes                         |P|
  1786       mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1787             |             Forward pointer to next chunk in list             |
  1788             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1789             |             Back pointer to previous chunk in list            |
  1790             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1791             |             Unused space (may be 0 bytes long)                .
  1792             .                                                               .
  1793             .                                                               |
  1794 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1795     `foot:' |             Size of chunk, in bytes                           |
  1796             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1797 
  1798   Larger chunks are kept in a form of bitwise digital trees (aka
  1799   tries) keyed on chunksizes.  Because malloc_tree_chunks are only for
  1800   free chunks greater than 256 bytes, their size doesn't impose any
  1801   constraints on user chunk sizes.  Each node looks like:
  1802 
  1803     chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1804             |             Size of previous chunk                            |
  1805             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1806     `head:' |             Size of chunk, in bytes                         |P|
  1807       mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1808             |             Forward pointer to next chunk of same size        |
  1809             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1810             |             Back pointer to previous chunk of same size       |
  1811             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1812             |             Pointer to left child (child[0])                  |
  1813             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1814             |             Pointer to right child (child[1])                 |
  1815             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1816             |             Pointer to parent                                 |
  1817             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1818             |             bin index of this chunk                           |
  1819             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1820             |             Unused space                                      .
  1821             .                                                               |
  1822 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1823     `foot:' |             Size of chunk, in bytes                           |
  1824             +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  1825 
  1826   Each tree holding treenodes is a tree of unique chunk sizes.  Chunks
  1827   of the same size are arranged in a circularly-linked list, with only
  1828   the oldest chunk (the next to be used, in our FIFO ordering)
  1829   actually in the tree.  (Tree members are distinguished by a non-null
  1830   parent pointer.)  If a chunk with the same size an an existing node
  1831   is inserted, it is linked off the existing node using pointers that
  1832   work in the same way as fd/bk pointers of small chunks.
  1833 
  1834   Each tree contains a power of 2 sized range of chunk sizes (the
  1835   smallest is 0x100 <= x < 0x180), which is is divided in half at each
  1836   tree level, with the chunks in the smaller half of the range (0x100
  1837   <= x < 0x140 for the top nose) in the left subtree and the larger
  1838   half (0x140 <= x < 0x180) in the right subtree.  This is, of course,
  1839   done by inspecting individual bits.
  1840 
  1841   Using these rules, each node's left subtree contains all smaller
  1842   sizes than its right subtree.  However, the node at the root of each
  1843   subtree has no particular ordering relationship to either.  (The
  1844   dividing line between the subtree sizes is based on trie relation.)
  1845   If we remove the last chunk of a given size from the interior of the
  1846   tree, we need to replace it with a leaf node.  The tree ordering
  1847   rules permit a node to be replaced by any leaf below it.
  1848 
  1849   The smallest chunk in a tree (a common operation in a best-fit
  1850   allocator) can be found by walking a path to the leftmost leaf in
  1851   the tree.  Unlike a usual binary tree, where we follow left child
  1852   pointers until we reach a null, here we follow the right child
  1853   pointer any time the left one is null, until we reach a leaf with
  1854   both child pointers null. The smallest chunk in the tree will be
  1855   somewhere along that path.
  1856 
  1857   The worst case number of steps to add, find, or remove a node is
  1858   bounded by the number of bits differentiating chunks within
  1859   bins. Under current bin calculations, this ranges from 6 up to 21
  1860   (for 32 bit sizes) or up to 53 (for 64 bit sizes). The typical case
  1861   is of course much better.
  1862 */
  1863 
  1864 struct malloc_tree_chunk
  1865 {
  1866     /* The first four fields must be compatible with malloc_chunk */
  1867     size_t prev_foot;
  1868     size_t head;
  1869     struct malloc_tree_chunk *fd;
  1870     struct malloc_tree_chunk *bk;
  1871 
  1872     struct malloc_tree_chunk *child[2];
  1873     struct malloc_tree_chunk *parent;
  1874     bindex_t index;
  1875 };
  1876 
  1877 typedef struct malloc_tree_chunk tchunk;
  1878 typedef struct malloc_tree_chunk *tchunkptr;
  1879 typedef struct malloc_tree_chunk *tbinptr;      /* The type of bins of trees */
  1880 
  1881 /* A little helper macro for trees */
  1882 #define leftmost_child(t) ((t)->child[0] != 0? (t)->child[0] : (t)->child[1])
  1883 
  1884 /* ----------------------------- Segments -------------------------------- */
  1885 
  1886 /*
  1887   Each malloc space may include non-contiguous segments, held in a
  1888   list headed by an embedded malloc_segment record representing the
  1889   top-most space. Segments also include flags holding properties of
  1890   the space. Large chunks that are directly allocated by mmap are not
  1891   included in this list. They are instead independently created and
  1892   destroyed without otherwise keeping track of them.
  1893 
  1894   Segment management mainly comes into play for spaces allocated by
  1895   MMAP.  Any call to MMAP might or might not return memory that is
  1896   adjacent to an existing segment.  MORECORE normally contiguously
  1897   extends the current space, so this space is almost always adjacent,
  1898   which is simpler and faster to deal with. (This is why MORECORE is
  1899   used preferentially to MMAP when both are available -- see
  1900   sys_alloc.)  When allocating using MMAP, we don't use any of the
  1901   hinting mechanisms (inconsistently) supported in various
  1902   implementations of unix mmap, or distinguish reserving from
  1903   committing memory. Instead, we just ask for space, and exploit
  1904   contiguity when we get it.  It is probably possible to do
  1905   better than this on some systems, but no general scheme seems
  1906   to be significantly better.
  1907 
  1908   Management entails a simpler variant of the consolidation scheme
  1909   used for chunks to reduce fragmentation -- new adjacent memory is
  1910   normally prepended or appended to an existing segment. However,
  1911   there are limitations compared to chunk consolidation that mostly
  1912   reflect the fact that segment processing is relatively infrequent
  1913   (occurring only when getting memory from system) and that we
  1914   don't expect to have huge numbers of segments:
  1915 
  1916   * Segments are not indexed, so traversal requires linear scans.  (It
  1917     would be possible to index these, but is not worth the extra
  1918     overhead and complexity for most programs on most platforms.)
  1919   * New segments are only appended to old ones when holding top-most
  1920     memory; if they cannot be prepended to others, they are held in
  1921     different segments.
  1922 
  1923   Except for the top-most segment of an mstate, each segment record
  1924   is kept at the tail of its segment. Segments are added by pushing
  1925   segment records onto the list headed by &mstate.seg for the
  1926   containing mstate.
  1927 
  1928   Segment flags control allocation/merge/deallocation policies:
  1929   * If EXTERN_BIT set, then we did not allocate this segment,
  1930     and so should not try to deallocate or merge with others.
  1931     (This currently holds only for the initial segment passed
  1932     into create_mspace_with_base.)
  1933   * If IS_MMAPPED_BIT set, the segment may be merged with
  1934     other surrounding mmapped segments and trimmed/de-allocated
  1935     using munmap.
  1936   * If neither bit is set, then the segment was obtained using
  1937     MORECORE so can be merged with surrounding MORECORE'd segments
  1938     and deallocated/trimmed using MORECORE with negative arguments.
  1939 */
  1940 
  1941 struct malloc_segment
  1942 {
  1943     char *base;                 /* base address */
  1944     size_t size;                /* allocated size */
  1945     struct malloc_segment *next;        /* ptr to next segment */
  1946     flag_t sflags;              /* mmap and extern flag */
  1947 };
  1948 
  1949 #define is_mmapped_segment(S)  ((S)->sflags & IS_MMAPPED_BIT)
  1950 #define is_extern_segment(S)   ((S)->sflags & EXTERN_BIT)
  1951 
  1952 typedef struct malloc_segment msegment;
  1953 typedef struct malloc_segment *msegmentptr;
  1954 
  1955 /* ---------------------------- malloc_state ----------------------------- */
  1956 
  1957 /*
  1958    A malloc_state holds all of the bookkeeping for a space.
  1959    The main fields are:
  1960 
  1961   Top
  1962     The topmost chunk of the currently active segment. Its size is
  1963     cached in topsize.  The actual size of topmost space is
  1964     topsize+TOP_FOOT_SIZE, which includes space reserved for adding
  1965     fenceposts and segment records if necessary when getting more
  1966     space from the system.  The size at which to autotrim top is
  1967     cached from mparams in trim_check, except that it is disabled if
  1968     an autotrim fails.
  1969 
  1970   Designated victim (dv)
  1971     This is the preferred chunk for servicing small requests that
  1972     don't have exact fits.  It is normally the chunk split off most
  1973     recently to service another small request.  Its size is cached in
  1974     dvsize. The link fields of this chunk are not maintained since it
  1975     is not kept in a bin.
  1976 
  1977   SmallBins
  1978     An array of bin headers for free chunks.  These bins hold chunks
  1979     with sizes less than MIN_LARGE_SIZE bytes. Each bin contains
  1980     chunks of all the same size, spaced 8 bytes apart.  To simplify
  1981     use in double-linked lists, each bin header acts as a malloc_chunk
  1982     pointing to the real first node, if it exists (else pointing to
  1983     itself).  This avoids special-casing for headers.  But to avoid
  1984     waste, we allocate only the fd/bk pointers of bins, and then use
  1985     repositioning tricks to treat these as the fields of a chunk.
  1986 
  1987   TreeBins
  1988     Treebins are pointers to the roots of trees holding a range of
  1989     sizes. There are 2 equally spaced treebins for each power of two
  1990     from TREE_SHIFT to TREE_SHIFT+16. The last bin holds anything
  1991     larger.
  1992 
  1993   Bin maps
  1994     There is one bit map for small bins ("smallmap") and one for
  1995     treebins ("treemap).  Each bin sets its bit when non-empty, and
  1996     clears the bit when empty.  Bit operations are then used to avoid
  1997     bin-by-bin searching -- nearly all "search" is done without ever
  1998     looking at bins that won't be selected.  The bit maps
  1999     conservatively use 32 bits per map word, even if on 64bit system.
  2000     For a good description of some of the bit-based techniques used
  2001     here, see Henry S. Warren Jr's book "Hacker's Delight" (and
  2002     supplement at http://hackersdelight.org/). Many of these are
  2003     intended to reduce the branchiness of paths through malloc etc, as
  2004     well as to reduce the number of memory locations read or written.
  2005 
  2006   Segments
  2007     A list of segments headed by an embedded malloc_segment record
  2008     representing the initial space.
  2009 
  2010   Address check support
  2011     The least_addr field is the least address ever obtained from
  2012     MORECORE or MMAP. Attempted frees and reallocs of any address less
  2013     than this are trapped (unless INSECURE is defined).
  2014 
  2015   Magic tag
  2016     A cross-check field that should always hold same value as mparams.magic.
  2017 
  2018   Flags
  2019     Bits recording whether to use MMAP, locks, or contiguous MORECORE
  2020 
  2021   Statistics
  2022     Each space keeps track of current and maximum system memory
  2023     obtained via MORECORE or MMAP.
  2024 
  2025   Locking
  2026     If USE_LOCKS is defined, the "mutex" lock is acquired and released
  2027     around every public call using this mspace.
  2028 */
  2029 
  2030 /* Bin types, widths and sizes */
  2031 #define NSMALLBINS        (32U)
  2032 #define NTREEBINS         (32U)
  2033 #define SMALLBIN_SHIFT    (3U)
  2034 #define SMALLBIN_WIDTH    (SIZE_T_ONE << SMALLBIN_SHIFT)
  2035 #define TREEBIN_SHIFT     (8U)
  2036 #define MIN_LARGE_SIZE    (SIZE_T_ONE << TREEBIN_SHIFT)
  2037 #define MAX_SMALL_SIZE    (MIN_LARGE_SIZE - SIZE_T_ONE)
  2038 #define MAX_SMALL_REQUEST (MAX_SMALL_SIZE - CHUNK_ALIGN_MASK - CHUNK_OVERHEAD)
  2039 
  2040 struct malloc_state
  2041 {
  2042     binmap_t smallmap;
  2043     binmap_t treemap;
  2044     size_t dvsize;
  2045     size_t topsize;
  2046     char *least_addr;
  2047     mchunkptr dv;
  2048     mchunkptr top;
  2049     size_t trim_check;
  2050     size_t magic;
  2051     mchunkptr smallbins[(NSMALLBINS + 1) * 2];
  2052     tbinptr treebins[NTREEBINS];
  2053     size_t footprint;
  2054     size_t max_footprint;
  2055     flag_t mflags;
  2056 #if USE_LOCKS
  2057     MLOCK_T mutex;              /* locate lock among fields that rarely change */
  2058 #endif                          /* USE_LOCKS */
  2059     msegment seg;
  2060 };
  2061 
  2062 typedef struct malloc_state *mstate;
  2063 
  2064 /* ------------- Global malloc_state and malloc_params ------------------- */
  2065 
  2066 /*
  2067   malloc_params holds global properties, including those that can be
  2068   dynamically set using mallopt. There is a single instance, mparams,
  2069   initialized in init_mparams.
  2070 */
  2071 
  2072 struct malloc_params
  2073 {
  2074     size_t magic;
  2075     size_t page_size;
  2076     size_t granularity;
  2077     size_t mmap_threshold;
  2078     size_t trim_threshold;
  2079     flag_t default_mflags;
  2080 };
  2081 
  2082 static struct malloc_params mparams;
  2083 
  2084 /* The global malloc_state used for all non-"mspace" calls */
  2085 static struct malloc_state _gm_;
  2086 #define gm                 (&_gm_)
  2087 #define is_global(M)       ((M) == &_gm_)
  2088 #define is_initialized(M)  ((M)->top != 0)
  2089 
  2090 /* -------------------------- system alloc setup ------------------------- */
  2091 
  2092 /* Operations on mflags */
  2093 
  2094 #define use_lock(M)           ((M)->mflags &   USE_LOCK_BIT)
  2095 #define enable_lock(M)        ((M)->mflags |=  USE_LOCK_BIT)
  2096 #define disable_lock(M)       ((M)->mflags &= ~USE_LOCK_BIT)
  2097 
  2098 #define use_mmap(M)           ((M)->mflags &   USE_MMAP_BIT)
  2099 #define enable_mmap(M)        ((M)->mflags |=  USE_MMAP_BIT)
  2100 #define disable_mmap(M)       ((M)->mflags &= ~USE_MMAP_BIT)
  2101 
  2102 #define use_noncontiguous(M)  ((M)->mflags &   USE_NONCONTIGUOUS_BIT)
  2103 #define disable_contiguous(M) ((M)->mflags |=  USE_NONCONTIGUOUS_BIT)
  2104 
  2105 #define set_lock(M,L)\
  2106  ((M)->mflags = (L)?\
  2107   ((M)->mflags | USE_LOCK_BIT) :\
  2108   ((M)->mflags & ~USE_LOCK_BIT))
  2109 
  2110 /* page-align a size */
  2111 #define page_align(S)\
  2112  (((S) + (mparams.page_size)) & ~(mparams.page_size - SIZE_T_ONE))
  2113 
  2114 /* granularity-align a size */
  2115 #define granularity_align(S)\
  2116   (((S) + (mparams.granularity)) & ~(mparams.granularity - SIZE_T_ONE))
  2117 
  2118 #define is_page_aligned(S)\
  2119    (((size_t)(S) & (mparams.page_size - SIZE_T_ONE)) == 0)
  2120 #define is_granularity_aligned(S)\
  2121    (((size_t)(S) & (mparams.granularity - SIZE_T_ONE)) == 0)
  2122 
  2123 /*  True if segment S holds address A */
  2124 #define segment_holds(S, A)\
  2125   ((char*)(A) >= S->base && (char*)(A) < S->base + S->size)
  2126 
  2127 /* Return segment holding given address */
  2128 static msegmentptr
  2129 segment_holding (mstate m, char *addr)
  2130 {
  2131     msegmentptr sp = &m->seg;
  2132     for (;;) {
  2133         if (addr >= sp->base && addr < sp->base + sp->size)
  2134             return sp;
  2135         if ((sp = sp->next) == 0)
  2136             return 0;
  2137     }
  2138 }
  2139 
  2140 /* Return true if segment contains a segment link */
  2141 static int
  2142 has_segment_link (mstate m, msegmentptr ss)
  2143 {
  2144     msegmentptr sp = &m->seg;
  2145     for (;;) {
  2146         if ((char *) sp >= ss->base && (char *) sp < ss->base + ss->size)
  2147             return 1;
  2148         if ((sp = sp->next) == 0)
  2149             return 0;
  2150     }
  2151 }
  2152 
  2153 #ifndef MORECORE_CANNOT_TRIM
  2154 #define should_trim(M,s)  ((s) > (M)->trim_check)
  2155 #else /* MORECORE_CANNOT_TRIM */
  2156 #define should_trim(M,s)  (0)
  2157 #endif /* MORECORE_CANNOT_TRIM */
  2158 
  2159 /*
  2160   TOP_FOOT_SIZE is padding at the end of a segment, including space
  2161   that may be needed to place segment records and fenceposts when new
  2162   noncontiguous segments are added.
  2163 */
  2164 #define TOP_FOOT_SIZE\
  2165   (align_offset(chunk2mem(0))+pad_request(sizeof(struct malloc_segment))+MIN_CHUNK_SIZE)
  2166 
  2167 
  2168 /* -------------------------------  Hooks -------------------------------- */
  2169 
  2170 /*
  2171   PREACTION should be defined to return 0 on success, and nonzero on
  2172   failure. If you are not using locking, you can redefine these to do
  2173   anything you like.
  2174 */
  2175 
  2176 #if USE_LOCKS
  2177 
  2178 /* Ensure locks are initialized */
  2179 #define GLOBALLY_INITIALIZE() (mparams.page_size == 0 && init_mparams())
  2180 
  2181 #define PREACTION(M)  ((GLOBALLY_INITIALIZE() || use_lock(M))? ACQUIRE_LOCK(&(M)->mutex) : 0)
  2182 #define POSTACTION(M) { if (use_lock(M)) RELEASE_LOCK(&(M)->mutex); }
  2183 #else /* USE_LOCKS */
  2184 
  2185 #ifndef PREACTION
  2186 #define PREACTION(M) (0)
  2187 #endif /* PREACTION */
  2188 
  2189 #ifndef POSTACTION
  2190 #define POSTACTION(M)
  2191 #endif /* POSTACTION */
  2192 
  2193 #endif /* USE_LOCKS */
  2194 
  2195 /*
  2196   CORRUPTION_ERROR_ACTION is triggered upon detected bad addresses.
  2197   USAGE_ERROR_ACTION is triggered on detected bad frees and
  2198   reallocs. The argument p is an address that might have triggered the
  2199   fault. It is ignored by the two predefined actions, but might be
  2200   useful in custom actions that try to help diagnose errors.
  2201 */
  2202 
  2203 #if PROCEED_ON_ERROR
  2204 
  2205 /* A count of the number of corruption errors causing resets */
  2206 int malloc_corruption_error_count;
  2207 
  2208 /* default corruption action */
  2209 static void reset_on_error (mstate m);
  2210 
  2211 #define CORRUPTION_ERROR_ACTION(m)  reset_on_error(m)
  2212 #define USAGE_ERROR_ACTION(m, p)
  2213 
  2214 #else /* PROCEED_ON_ERROR */
  2215 
  2216 #ifndef CORRUPTION_ERROR_ACTION
  2217 #define CORRUPTION_ERROR_ACTION(m) ABORT
  2218 #endif /* CORRUPTION_ERROR_ACTION */
  2219 
  2220 #ifndef USAGE_ERROR_ACTION
  2221 #define USAGE_ERROR_ACTION(m,p) ABORT
  2222 #endif /* USAGE_ERROR_ACTION */
  2223 
  2224 #endif /* PROCEED_ON_ERROR */
  2225 
  2226 /* -------------------------- Debugging setup ---------------------------- */
  2227 
  2228 #if ! DEBUG
  2229 
  2230 #define check_free_chunk(M,P)
  2231 #define check_inuse_chunk(M,P)
  2232 #define check_malloced_chunk(M,P,N)
  2233 #define check_mmapped_chunk(M,P)
  2234 #define check_malloc_state(M)
  2235 #define check_top_chunk(M,P)
  2236 
  2237 #else /* DEBUG */
  2238 #define check_free_chunk(M,P)       do_check_free_chunk(M,P)
  2239 #define check_inuse_chunk(M,P)      do_check_inuse_chunk(M,P)
  2240 #define check_top_chunk(M,P)        do_check_top_chunk(M,P)
  2241 #define check_malloced_chunk(M,P,N) do_check_malloced_chunk(M,P,N)
  2242 #define check_mmapped_chunk(M,P)    do_check_mmapped_chunk(M,P)
  2243 #define check_malloc_state(M)       do_check_malloc_state(M)
  2244 
  2245 static void do_check_any_chunk (mstate m, mchunkptr p);
  2246 static void do_check_top_chunk (mstate m, mchunkptr p);
  2247 static void do_check_mmapped_chunk (mstate m, mchunkptr p);
  2248 static void do_check_inuse_chunk (mstate m, mchunkptr p);
  2249 static void do_check_free_chunk (mstate m, mchunkptr p);
  2250 static void do_check_malloced_chunk (mstate m, void *mem, size_t s);
  2251 static void do_check_tree (mstate m, tchunkptr t);
  2252 static void do_check_treebin (mstate m, bindex_t i);
  2253 static void do_check_smallbin (mstate m, bindex_t i);
  2254 static void do_check_malloc_state (mstate m);
  2255 static int bin_find (mstate m, mchunkptr x);
  2256 static size_t traverse_and_check (mstate m);
  2257 #endif /* DEBUG */
  2258 
  2259 /* ---------------------------- Indexing Bins ---------------------------- */
  2260 
  2261 #define is_small(s)         (((s) >> SMALLBIN_SHIFT) < NSMALLBINS)
  2262 #define small_index(s)      ((s)  >> SMALLBIN_SHIFT)
  2263 #define small_index2size(i) ((i)  << SMALLBIN_SHIFT)
  2264 #define MIN_SMALL_INDEX     (small_index(MIN_CHUNK_SIZE))
  2265 
  2266 /* addressing by index. See above about smallbin repositioning */
  2267 #define smallbin_at(M, i)   ((sbinptr)((char*)&((M)->smallbins[(i)<<1])))
  2268 #define treebin_at(M,i)     (&((M)->treebins[i]))
  2269 
  2270 /* assign tree index for size S to variable I */
  2271 #if defined(__GNUC__) && defined(i386)
  2272 #define compute_tree_index(S, I)\
  2273 {\
  2274   size_t X = S >> TREEBIN_SHIFT;\
  2275   if (X == 0)\
  2276     I = 0;\
  2277   else if (X > 0xFFFF)\
  2278     I = NTREEBINS-1;\
  2279   else {\
  2280     unsigned int K;\
  2281     __asm__("bsrl %1,%0\n\t" : "=r" (K) : "rm"  (X));\
  2282     I =  (bindex_t)((K << 1) + ((S >> (K + (TREEBIN_SHIFT-1)) & 1)));\
  2283   }\
  2284 }
  2285 #else /* GNUC */
  2286 #define compute_tree_index(S, I)\
  2287 {\
  2288   size_t X = S >> TREEBIN_SHIFT;\
  2289   if (X == 0)\
  2290     I = 0;\
  2291   else if (X > 0xFFFF)\
  2292     I = NTREEBINS-1;\
  2293   else {\
  2294     unsigned int Y = (unsigned int)X;\
  2295     unsigned int N = ((Y - 0x100) >> 16) & 8;\
  2296     unsigned int K = (((Y <<= N) - 0x1000) >> 16) & 4;\
  2297     N += K;\
  2298     N += K = (((Y <<= K) - 0x4000) >> 16) & 2;\
  2299     K = 14 - N + ((Y <<= K) >> 15);\
  2300     I = (K << 1) + ((S >> (K + (TREEBIN_SHIFT-1)) & 1));\
  2301   }\
  2302 }
  2303 #endif /* GNUC */
  2304 
  2305 /* Bit representing maximum resolved size in a treebin at i */
  2306 #define bit_for_tree_index(i) \
  2307    (i == NTREEBINS-1)? (SIZE_T_BITSIZE-1) : (((i) >> 1) + TREEBIN_SHIFT - 2)
  2308 
  2309 /* Shift placing maximum resolved bit in a treebin at i as sign bit */
  2310 #define leftshift_for_tree_index(i) \
  2311    ((i == NTREEBINS-1)? 0 : \
  2312     ((SIZE_T_BITSIZE-SIZE_T_ONE) - (((i) >> 1) + TREEBIN_SHIFT - 2)))
  2313 
  2314 /* The size of the smallest chunk held in bin with index i */
  2315 #define minsize_for_tree_index(i) \
  2316    ((SIZE_T_ONE << (((i) >> 1) + TREEBIN_SHIFT)) |  \
  2317    (((size_t)((i) & SIZE_T_ONE)) << (((i) >> 1) + TREEBIN_SHIFT - 1)))
  2318 
  2319 
  2320 /* ------------------------ Operations on bin maps ----------------------- */
  2321 
  2322 /* bit corresponding to given index */
  2323 #define idx2bit(i)              ((binmap_t)(1) << (i))
  2324 
  2325 /* Mark/Clear bits with given index */
  2326 #define mark_smallmap(M,i)      ((M)->smallmap |=  idx2bit(i))
  2327 #define clear_smallmap(M,i)     ((M)->smallmap &= ~idx2bit(i))
  2328 #define smallmap_is_marked(M,i) ((M)->smallmap &   idx2bit(i))
  2329 
  2330 #define mark_treemap(M,i)       ((M)->treemap  |=  idx2bit(i))
  2331 #define clear_treemap(M,i)      ((M)->treemap  &= ~idx2bit(i))
  2332 #define treemap_is_marked(M,i)  ((M)->treemap  &   idx2bit(i))
  2333 
  2334 /* index corresponding to given bit */
  2335 
  2336 #if defined(__GNUC__) && defined(i386)
  2337 #define compute_bit2idx(X, I)\
  2338 {\
  2339   unsigned int J;\
  2340   __asm__("bsfl %1,%0\n\t" : "=r" (J) : "rm" (X));\
  2341   I = (bindex_t)J;\
  2342 }
  2343 
  2344 #else /* GNUC */
  2345 #if  USE_BUILTIN_FFS
  2346 #define compute_bit2idx(X, I) I = ffs(X)-1
  2347 
  2348 #else /* USE_BUILTIN_FFS */
  2349 #define compute_bit2idx(X, I)\
  2350 {\
  2351   unsigned int Y = X - 1;\
  2352   unsigned int K = Y >> (16-4) & 16;\
  2353   unsigned int N = K;        Y >>= K;\
  2354   N += K = Y >> (8-3) &  8;  Y >>= K;\
  2355   N += K = Y >> (4-2) &  4;  Y >>= K;\
  2356   N += K = Y >> (2-1) &  2;  Y >>= K;\
  2357   N += K = Y >> (1-0) &  1;  Y >>= K;\
  2358   I = (bindex_t)(N + Y);\
  2359 }
  2360 #endif /* USE_BUILTIN_FFS */
  2361 #endif /* GNUC */
  2362 
  2363 /* isolate the least set bit of a bitmap */
  2364 #define least_bit(x)         ((x) & -(x))
  2365 
  2366 /* mask with all bits to left of least bit of x on */
  2367 #define left_bits(x)         ((x<<1) | -(x<<1))
  2368 
  2369 /* mask with all bits to left of or equal to least bit of x on */
  2370 #define same_or_left_bits(x) ((x) | -(x))
  2371 
  2372 
  2373 /* ----------------------- Runtime Check Support ------------------------- */
  2374 
  2375 /*
  2376   For security, the main invariant is that malloc/free/etc never
  2377   writes to a static address other than malloc_state, unless static
  2378   malloc_state itself has been corrupted, which cannot occur via
  2379   malloc (because of these checks). In essence this means that we
  2380   believe all pointers, sizes, maps etc held in malloc_state, but
  2381   check all of those linked or offsetted from other embedded data
  2382   structures.  These checks are interspersed with main code in a way
  2383   that tends to minimize their run-time cost.
  2384 
  2385   When FOOTERS is defined, in addition to range checking, we also
  2386   verify footer fields of inuse chunks, which can be used guarantee
  2387   that the mstate controlling malloc/free is intact.  This is a
  2388   streamlined version of the approach described by William Robertson
  2389   et al in "Run-time Detection of Heap-based Overflows" LISA'03
  2390   http://www.usenix.org/events/lisa03/tech/robertson.html The footer
  2391   of an inuse chunk holds the xor of its mstate and a random seed,
  2392   that is checked upon calls to free() and realloc().  This is
  2393   (probablistically) unguessable from outside the program, but can be
  2394   computed by any code successfully malloc'ing any chunk, so does not
  2395   itself provide protection against code that has already broken
  2396   security through some other means.  Unlike Robertson et al, we
  2397   always dynamically check addresses of all offset chunks (previous,
  2398   next, etc). This turns out to be cheaper than relying on hashes.
  2399 */
  2400 
  2401 #if !INSECURE
  2402 /* Check if address a is at least as high as any from MORECORE or MMAP */
  2403 #define ok_address(M, a) ((char*)(a) >= (M)->least_addr)
  2404 /* Check if address of next chunk n is higher than base chunk p */
  2405 #define ok_next(p, n)    ((char*)(p) < (char*)(n))
  2406 /* Check if p has its cinuse bit on */
  2407 #define ok_cinuse(p)     cinuse(p)
  2408 /* Check if p has its pinuse bit on */
  2409 #define ok_pinuse(p)     pinuse(p)
  2410 
  2411 #else /* !INSECURE */
  2412 #define ok_address(M, a) (1)
  2413 #define ok_next(b, n)    (1)
  2414 #define ok_cinuse(p)     (1)
  2415 #define ok_pinuse(p)     (1)
  2416 #endif /* !INSECURE */
  2417 
  2418 #if (FOOTERS && !INSECURE)
  2419 /* Check if (alleged) mstate m has expected magic field */
  2420 #define ok_magic(M)      ((M)->magic == mparams.magic)
  2421 #else /* (FOOTERS && !INSECURE) */
  2422 #define ok_magic(M)      (1)
  2423 #endif /* (FOOTERS && !INSECURE) */
  2424 
  2425 
  2426 /* In gcc, use __builtin_expect to minimize impact of checks */
  2427 #if !INSECURE
  2428 #if defined(__GNUC__) && __GNUC__ >= 3
  2429 #define RTCHECK(e)  __builtin_expect(e, 1)
  2430 #else /* GNUC */
  2431 #define RTCHECK(e)  (e)
  2432 #endif /* GNUC */
  2433 #else /* !INSECURE */
  2434 #define RTCHECK(e)  (1)
  2435 #endif /* !INSECURE */
  2436 
  2437 /* macros to set up inuse chunks with or without footers */
  2438 
  2439 #if !FOOTERS
  2440 
  2441 #define mark_inuse_foot(M,p,s)
  2442 
  2443 /* Set cinuse bit and pinuse bit of next chunk */
  2444 #define set_inuse(M,p,s)\
  2445   ((p)->head = (((p)->head & PINUSE_BIT)|s|CINUSE_BIT),\
  2446   ((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT)
  2447 
  2448 /* Set cinuse and pinuse of this chunk and pinuse of next chunk */
  2449 #define set_inuse_and_pinuse(M,p,s)\
  2450   ((p)->head = (s|PINUSE_BIT|CINUSE_BIT),\
  2451   ((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT)
  2452 
  2453 /* Set size, cinuse and pinuse bit of this chunk */
  2454 #define set_size_and_pinuse_of_inuse_chunk(M, p, s)\
  2455   ((p)->head = (s|PINUSE_BIT|CINUSE_BIT))
  2456 
  2457 #else /* FOOTERS */
  2458 
  2459 /* Set foot of inuse chunk to be xor of mstate and seed */
  2460 #define mark_inuse_foot(M,p,s)\
  2461   (((mchunkptr)((char*)(p) + (s)))->prev_foot = ((size_t)(M) ^ mparams.magic))
  2462 
  2463 #define get_mstate_for(p)\
  2464   ((mstate)(((mchunkptr)((char*)(p) +\
  2465     (chunksize(p))))->prev_foot ^ mparams.magic))
  2466 
  2467 #define set_inuse(M,p,s)\
  2468   ((p)->head = (((p)->head & PINUSE_BIT)|s|CINUSE_BIT),\
  2469   (((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT), \
  2470   mark_inuse_foot(M,p,s))
  2471 
  2472 #define set_inuse_and_pinuse(M,p,s)\
  2473   ((p)->head = (s|PINUSE_BIT|CINUSE_BIT),\
  2474   (((mchunkptr)(((char*)(p)) + (s)))->head |= PINUSE_BIT),\
  2475  mark_inuse_foot(M,p,s))
  2476 
  2477 #define set_size_and_pinuse_of_inuse_chunk(M, p, s)\
  2478   ((p)->head = (s|PINUSE_BIT|CINUSE_BIT),\
  2479   mark_inuse_foot(M, p, s))
  2480 
  2481 #endif /* !FOOTERS */
  2482 
  2483 /* ---------------------------- setting mparams -------------------------- */
  2484 
  2485 /* Initialize mparams */
  2486 static int
  2487 init_mparams (void)
  2488 {
  2489     if (mparams.page_size == 0) {
  2490         size_t s;
  2491 
  2492         mparams.mmap_threshold = DEFAULT_MMAP_THRESHOLD;
  2493         mparams.trim_threshold = DEFAULT_TRIM_THRESHOLD;
  2494 #if MORECORE_CONTIGUOUS
  2495         mparams.default_mflags = USE_LOCK_BIT | USE_MMAP_BIT;
  2496 #else /* MORECORE_CONTIGUOUS */
  2497         mparams.default_mflags =
  2498             USE_LOCK_BIT | USE_MMAP_BIT | USE_NONCONTIGUOUS_BIT;
  2499 #endif /* MORECORE_CONTIGUOUS */
  2500 
  2501 #if (FOOTERS && !INSECURE)
  2502         {
  2503 #if USE_DEV_RANDOM
  2504             int fd;
  2505             unsigned char buf[sizeof (size_t)];
  2506             /* Try to use /dev/urandom, else fall back on using time */
  2507             if ((fd = open ("/dev/urandom", O_RDONLY)) >= 0 &&
  2508                 read (fd, buf, sizeof (buf)) == sizeof (buf)) {
  2509                 s = *((size_t *) buf);
  2510                 close (fd);
  2511             } else
  2512 #endif /* USE_DEV_RANDOM */
  2513                 s = (size_t) (time (0) ^ (size_t) 0x55555555U);
  2514 
  2515             s |= (size_t) 8U;   /* ensure nonzero */
  2516             s &= ~(size_t) 7U;  /* improve chances of fault for bad values */
  2517 
  2518         }
  2519 #else /* (FOOTERS && !INSECURE) */
  2520         s = (size_t) 0x58585858U;
  2521 #endif /* (FOOTERS && !INSECURE) */
  2522         ACQUIRE_MAGIC_INIT_LOCK ();
  2523         if (mparams.magic == 0) {
  2524             mparams.magic = s;
  2525             /* Set up lock for main malloc area */
  2526             INITIAL_LOCK (&gm->mutex);
  2527             gm->mflags = mparams.default_mflags;
  2528         }
  2529         RELEASE_MAGIC_INIT_LOCK ();
  2530 
  2531 #ifndef WIN32
  2532         mparams.page_size = malloc_getpagesize;
  2533         mparams.granularity = ((DEFAULT_GRANULARITY != 0) ?
  2534                                DEFAULT_GRANULARITY : mparams.page_size);
  2535 #else /* WIN32 */
  2536         {
  2537             SYSTEM_INFO system_info;
  2538             GetSystemInfo (&system_info);
  2539             mparams.page_size = system_info.dwPageSize;
  2540             mparams.granularity = system_info.dwAllocationGranularity;
  2541         }
  2542 #endif /* WIN32 */
  2543 
  2544         /* Sanity-check configuration:
  2545            size_t must be unsigned and as wide as pointer type.
  2546            ints must be at least 4 bytes.
  2547            alignment must be at least 8.
  2548            Alignment, min chunk size, and page size must all be powers of 2.
  2549          */
  2550         if ((sizeof (size_t) != sizeof (char *)) ||
  2551             (MAX_SIZE_T < MIN_CHUNK_SIZE) ||
  2552             (sizeof (int) < 4) ||
  2553             (MALLOC_ALIGNMENT < (size_t) 8U) ||
  2554             ((MALLOC_ALIGNMENT & (MALLOC_ALIGNMENT - SIZE_T_ONE)) != 0) ||
  2555             ((MCHUNK_SIZE & (MCHUNK_SIZE - SIZE_T_ONE)) != 0) ||
  2556             ((mparams.granularity & (mparams.granularity - SIZE_T_ONE)) != 0)
  2557             || ((mparams.page_size & (mparams.page_size - SIZE_T_ONE)) != 0))
  2558             ABORT;
  2559     }
  2560     return 0;
  2561 }
  2562 
  2563 /* support for mallopt */
  2564 static int
  2565 change_mparam (int param_number, int value)
  2566 {
  2567     size_t val = (size_t) value;
  2568     init_mparams ();
  2569     switch (param_number) {
  2570     case M_TRIM_THRESHOLD:
  2571         mparams.trim_threshold = val;
  2572         return 1;
  2573     case M_GRANULARITY:
  2574         if (val >= mparams.page_size && ((val & (val - 1)) == 0)) {
  2575             mparams.granularity = val;
  2576             return 1;
  2577         } else
  2578             return 0;
  2579     case M_MMAP_THRESHOLD:
  2580         mparams.mmap_threshold = val;
  2581         return 1;
  2582     default:
  2583         return 0;
  2584     }
  2585 }
  2586 
  2587 #if DEBUG
  2588 /* ------------------------- Debugging Support --------------------------- */
  2589 
  2590 /* Check properties of any chunk, whether free, inuse, mmapped etc  */
  2591 static void
  2592 do_check_any_chunk (mstate m, mchunkptr p)
  2593 {
  2594     assert ((is_aligned (chunk2mem (p))) || (p->head == FENCEPOST_HEAD));
  2595     assert (ok_address (m, p));
  2596 }
  2597 
  2598 /* Check properties of top chunk */
  2599 static void
  2600 do_check_top_chunk (mstate m, mchunkptr p)
  2601 {
  2602     msegmentptr sp = segment_holding (m, (char *) p);
  2603     size_t sz = chunksize (p);
  2604     assert (sp != 0);
  2605     assert ((is_aligned (chunk2mem (p))) || (p->head == FENCEPOST_HEAD));
  2606     assert (ok_address (m, p));
  2607     assert (sz == m->topsize);
  2608     assert (sz > 0);
  2609     assert (sz == ((sp->base + sp->size) - (char *) p) - TOP_FOOT_SIZE);
  2610     assert (pinuse (p));
  2611     assert (!next_pinuse (p));
  2612 }
  2613 
  2614 /* Check properties of (inuse) mmapped chunks */
  2615 static void
  2616 do_check_mmapped_chunk (mstate m, mchunkptr p)
  2617 {
  2618     size_t sz = chunksize (p);
  2619     size_t len = (sz + (p->prev_foot & ~IS_MMAPPED_BIT) + MMAP_FOOT_PAD);
  2620     assert (is_mmapped (p));
  2621     assert (use_mmap (m));
  2622     assert ((is_aligned (chunk2mem (p))) || (p->head == FENCEPOST_HEAD));
  2623     assert (ok_address (m, p));
  2624     assert (!is_small (sz));
  2625     assert ((len & (mparams.page_size - SIZE_T_ONE)) == 0);
  2626     assert (chunk_plus_offset (p, sz)->head == FENCEPOST_HEAD);
  2627     assert (chunk_plus_offset (p, sz + SIZE_T_SIZE)->head == 0);
  2628 }
  2629 
  2630 /* Check properties of inuse chunks */
  2631 static void
  2632 do_check_inuse_chunk (mstate m, mchunkptr p)
  2633 {
  2634     do_check_any_chunk (m, p);
  2635     assert (cinuse (p));
  2636     assert (next_pinuse (p));
  2637     /* If not pinuse and not mmapped, previous chunk has OK offset */
  2638     assert (is_mmapped (p) || pinuse (p) || next_chunk (prev_chunk (p)) == p);
  2639     if (is_mmapped (p))
  2640         do_check_mmapped_chunk (m, p);
  2641 }
  2642 
  2643 /* Check properties of free chunks */
  2644 static void
  2645 do_check_free_chunk (mstate m, mchunkptr p)
  2646 {
  2647     size_t sz = p->head & ~(PINUSE_BIT | CINUSE_BIT);
  2648     mchunkptr next = chunk_plus_offset (p, sz);
  2649     do_check_any_chunk (m, p);
  2650     assert (!cinuse (p));
  2651     assert (!next_pinuse (p));
  2652     assert (!is_mmapped (p));
  2653     if (p != m->dv && p != m->top) {
  2654         if (sz >= MIN_CHUNK_SIZE) {
  2655             assert ((sz & CHUNK_ALIGN_MASK) == 0);
  2656             assert (is_aligned (chunk2mem (p)));
  2657             assert (next->prev_foot == sz);
  2658             assert (pinuse (p));
  2659             assert (next == m->top || cinuse (next));
  2660             assert (p->fd->bk == p);
  2661             assert (p->bk->fd == p);
  2662         } else                  /* markers are always of size SIZE_T_SIZE */
  2663             assert (sz == SIZE_T_SIZE);
  2664     }
  2665 }
  2666 
  2667 /* Check properties of malloced chunks at the point they are malloced */
  2668 static void
  2669 do_check_malloced_chunk (mstate m, void *mem, size_t s)
  2670 {
  2671     if (mem != 0) {
  2672         mchunkptr p = mem2chunk (mem);
  2673         size_t sz = p->head & ~(PINUSE_BIT | CINUSE_BIT);
  2674         do_check_inuse_chunk (m, p);
  2675         assert ((sz & CHUNK_ALIGN_MASK) == 0);
  2676         assert (sz >= MIN_CHUNK_SIZE);
  2677         assert (sz >= s);
  2678         /* unless mmapped, size is less than MIN_CHUNK_SIZE more than request */
  2679         assert (is_mmapped (p) || sz < (s + MIN_CHUNK_SIZE));
  2680     }
  2681 }
  2682 
  2683 /* Check a tree and its subtrees.  */
  2684 static void
  2685 do_check_tree (mstate m, tchunkptr t)
  2686 {
  2687     tchunkptr head = 0;
  2688     tchunkptr u = t;
  2689     bindex_t tindex = t->index;
  2690     size_t tsize = chunksize (t);
  2691     bindex_t idx;
  2692     compute_tree_index (tsize, idx);
  2693     assert (tindex == idx);
  2694     assert (tsize >= MIN_LARGE_SIZE);
  2695     assert (tsize >= minsize_for_tree_index (idx));
  2696     assert ((idx == NTREEBINS - 1)
  2697             || (tsize < minsize_for_tree_index ((idx + 1))));
  2698 
  2699     do {                        /* traverse through chain of same-sized nodes */
  2700         do_check_any_chunk (m, ((mchunkptr) u));
  2701         assert (u->index == tindex);
  2702         assert (chunksize (u) == tsize);
  2703         assert (!cinuse (u));
  2704         assert (!next_pinuse (u));
  2705         assert (u->fd->bk == u);
  2706         assert (u->bk->fd == u);
  2707         if (u->parent == 0) {
  2708             assert (u->child[0] == 0);
  2709             assert (u->child[1] == 0);
  2710         } else {
  2711             assert (head == 0); /* only one node on chain has parent */
  2712             head = u;
  2713             assert (u->parent != u);
  2714             assert (u->parent->child[0] == u ||
  2715                     u->parent->child[1] == u ||
  2716                     *((tbinptr *) (u->parent)) == u);
  2717             if (u->child[0] != 0) {
  2718                 assert (u->child[0]->parent == u);
  2719                 assert (u->child[0] != u);
  2720                 do_check_tree (m, u->child[0]);
  2721             }
  2722             if (u->child[1] != 0) {
  2723                 assert (u->child[1]->parent == u);
  2724                 assert (u->child[1] != u);
  2725                 do_check_tree (m, u->child[1]);
  2726             }
  2727             if (u->child[0] != 0 && u->child[1] != 0) {
  2728                 assert (chunksize (u->child[0]) < chunksize (u->child[1]));
  2729             }
  2730         }
  2731         u = u->fd;
  2732     }
  2733     while (u != t);
  2734     assert (head != 0);
  2735 }
  2736 
  2737 /*  Check all the chunks in a treebin.  */
  2738 static void
  2739 do_check_treebin (mstate m, bindex_t i)
  2740 {
  2741     tbinptr *tb = treebin_at (m, i);
  2742     tchunkptr t = *tb;
  2743     int empty = (m->treemap & (1U << i)) == 0;
  2744     if (t == 0)
  2745         assert (empty);
  2746     if (!empty)
  2747         do_check_tree (m, t);
  2748 }
  2749 
  2750 /*  Check all the chunks in a smallbin.  */
  2751 static void
  2752 do_check_smallbin (mstate m, bindex_t i)
  2753 {
  2754     sbinptr b = smallbin_at (m, i);
  2755     mchunkptr p = b->bk;
  2756     unsigned int empty = (m->smallmap & (1U << i)) == 0;
  2757     if (p == b)
  2758         assert (empty);
  2759     if (!empty) {
  2760         for (; p != b; p = p->bk) {
  2761             size_t size = chunksize (p);
  2762             mchunkptr q;
  2763             /* each chunk claims to be free */
  2764             do_check_free_chunk (m, p);
  2765             /* chunk belongs in bin */
  2766             assert (small_index (size) == i);
  2767             assert (p->bk == b || chunksize (p->bk) == chunksize (p));
  2768             /* chunk is followed by an inuse chunk */
  2769             q = next_chunk (p);
  2770             if (q->head != FENCEPOST_HEAD)
  2771                 do_check_inuse_chunk (m, q);
  2772         }
  2773     }
  2774 }
  2775 
  2776 /* Find x in a bin. Used in other check functions. */
  2777 static int
  2778 bin_find (mstate m, mchunkptr x)
  2779 {
  2780     size_t size = chunksize (x);
  2781     if (is_small (size)) {
  2782         bindex_t sidx = small_index (size);
  2783         sbinptr b = smallbin_at (m, sidx);
  2784         if (smallmap_is_marked (m, sidx)) {
  2785             mchunkptr p = b;
  2786             do {
  2787                 if (p == x)
  2788                     return 1;
  2789             }
  2790             while ((p = p->fd) != b);
  2791         }
  2792     } else {
  2793         bindex_t tidx;
  2794         compute_tree_index (size, tidx);
  2795         if (treemap_is_marked (m, tidx)) {
  2796             tchunkptr t = *treebin_at (m, tidx);
  2797             size_t sizebits = size << leftshift_for_tree_index (tidx);
  2798             while (t != 0 && chunksize (t) != size) {
  2799                 t = t->child[(sizebits >> (SIZE_T_BITSIZE - SIZE_T_ONE)) & 1];
  2800                 sizebits <<= 1;
  2801             }
  2802             if (t != 0) {
  2803                 tchunkptr u = t;
  2804                 do {
  2805                     if (u == (tchunkptr) x)
  2806                         return 1;
  2807                 }
  2808                 while ((u = u->fd) != t);
  2809             }
  2810         }
  2811     }
  2812     return 0;
  2813 }
  2814 
  2815 /* Traverse each chunk and check it; return total */
  2816 static size_t
  2817 traverse_and_check (mstate m)
  2818 {
  2819     size_t sum = 0;
  2820     if (is_initialized (m)) {
  2821         msegmentptr s = &m->seg;
  2822         sum += m->topsize + TOP_FOOT_SIZE;
  2823         while (s != 0) {
  2824             mchunkptr q = align_as_chunk (s->base);
  2825             mchunkptr lastq = 0;
  2826             assert (pinuse (q));
  2827             while (segment_holds (s, q) &&
  2828                    q != m->top && q->head != FENCEPOST_HEAD) {
  2829                 sum += chunksize (q);
  2830                 if (cinuse (q)) {
  2831                     assert (!bin_find (m, q));
  2832                     do_check_inuse_chunk (m, q);
  2833                 } else {
  2834                     assert (q == m->dv || bin_find (m, q));
  2835                     assert (lastq == 0 || cinuse (lastq));      /* Not 2 consecutive free */
  2836                     do_check_free_chunk (m, q);
  2837                 }
  2838                 lastq = q;
  2839                 q = next_chunk (q);
  2840             }
  2841             s = s->next;
  2842         }
  2843     }
  2844     return sum;
  2845 }
  2846 
  2847 /* Check all properties of malloc_state. */
  2848 static void
  2849 do_check_malloc_state (mstate m)
  2850 {
  2851     bindex_t i;
  2852     size_t total;
  2853     /* check bins */
  2854     for (i = 0; i < NSMALLBINS; ++i)
  2855         do_check_smallbin (m, i);
  2856     for (i = 0; i < NTREEBINS; ++i)
  2857         do_check_treebin (m, i);
  2858 
  2859     if (m->dvsize != 0) {       /* check dv chunk */
  2860         do_check_any_chunk (m, m->dv);
  2861         assert (m->dvsize == chunksize (m->dv));
  2862         assert (m->dvsize >= MIN_CHUNK_SIZE);
  2863         assert (bin_find (m, m->dv) == 0);
  2864     }
  2865 
  2866     if (m->top != 0) {          /* check top chunk */
  2867         do_check_top_chunk (m, m->top);
  2868         assert (m->topsize == chunksize (m->top));
  2869         assert (m->topsize > 0);
  2870         assert (bin_find (m, m->top) == 0);
  2871     }
  2872 
  2873     total = traverse_and_check (m);
  2874     assert (total <= m->footprint);
  2875     assert (m->footprint <= m->max_footprint);
  2876 }
  2877 #endif /* DEBUG */
  2878 
  2879 /* ----------------------------- statistics ------------------------------ */
  2880 
  2881 #if !NO_MALLINFO
  2882 static struct mallinfo
  2883 internal_mallinfo (mstate m)
  2884 {
  2885     struct mallinfo nm = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
  2886     if (!PREACTION (m)) {
  2887         check_malloc_state (m);
  2888         if (is_initialized (m)) {
  2889             size_t nfree = SIZE_T_ONE;  /* top always free */
  2890             size_t mfree = m->topsize + TOP_FOOT_SIZE;
  2891             size_t sum = mfree;
  2892             msegmentptr s = &m->seg;
  2893             while (s != 0) {
  2894                 mchunkptr q = align_as_chunk (s->base);
  2895                 while (segment_holds (s, q) &&
  2896                        q != m->top && q->head != FENCEPOST_HEAD) {
  2897                     size_t sz = chunksize (q);
  2898                     sum += sz;
  2899                     if (!cinuse (q)) {
  2900                         mfree += sz;
  2901                         ++nfree;
  2902                     }
  2903                     q = next_chunk (q);
  2904                 }
  2905                 s = s->next;
  2906             }
  2907 
  2908             nm.arena = sum;
  2909             nm.ordblks = nfree;
  2910             nm.hblkhd = m->footprint - sum;
  2911             nm.usmblks = m->max_footprint;
  2912             nm.uordblks = m->footprint - mfree;
  2913             nm.fordblks = mfree;
  2914             nm.keepcost = m->topsize;
  2915         }
  2916 
  2917         POSTACTION (m);
  2918     }
  2919     return nm;
  2920 }
  2921 #endif /* !NO_MALLINFO */
  2922 
  2923 static void
  2924 internal_malloc_stats (mstate m)
  2925 {
  2926     if (!PREACTION (m)) {
  2927         size_t maxfp = 0;
  2928         size_t fp = 0;
  2929         size_t used = 0;
  2930         check_malloc_state (m);
  2931         if (is_initialized (m)) {
  2932             msegmentptr s = &m->seg;
  2933             maxfp = m->max_footprint;
  2934             fp = m->footprint;
  2935             used = fp - (m->topsize + TOP_FOOT_SIZE);
  2936 
  2937             while (s != 0) {
  2938                 mchunkptr q = align_as_chunk (s->base);
  2939                 while (segment_holds (s, q) &&
  2940                        q != m->top && q->head != FENCEPOST_HEAD) {
  2941                     if (!cinuse (q))
  2942                         used -= chunksize (q);
  2943                     q = next_chunk (q);
  2944                 }
  2945                 s = s->next;
  2946             }
  2947         }
  2948 #ifndef LACKS_STDIO_H
  2949         fprintf (stderr, "max system bytes = %10lu\n",
  2950                  (unsigned long) (maxfp));
  2951         fprintf (stderr, "system bytes     = %10lu\n", (unsigned long) (fp));
  2952         fprintf (stderr, "in use bytes     = %10lu\n",
  2953                  (unsigned long) (used));
  2954 #endif
  2955 
  2956         POSTACTION (m);
  2957     }
  2958 }
  2959 
  2960 /* ----------------------- Operations on smallbins ----------------------- */
  2961 
  2962 /*
  2963   Various forms of linking and unlinking are defined as macros.  Even
  2964   the ones for trees, which are very long but have very short typical
  2965   paths.  This is ugly but reduces reliance on inlining support of
  2966   compilers.
  2967 */
  2968 
  2969 /* Link a free chunk into a smallbin  */
  2970 #define insert_small_chunk(M, P, S) {\
  2971   bindex_t I  = small_index(S);\
  2972   mchunkptr B = smallbin_at(M, I);\
  2973   mchunkptr F = B;\
  2974   assert(S >= MIN_CHUNK_SIZE);\
  2975   if (!smallmap_is_marked(M, I))\
  2976     mark_smallmap(M, I);\
  2977   else if (RTCHECK(ok_address(M, B->fd)))\
  2978     F = B->fd;\
  2979   else {\
  2980     CORRUPTION_ERROR_ACTION(M);\
  2981   }\
  2982   B->fd = P;\
  2983   F->bk = P;\
  2984   P->fd = F;\
  2985   P->bk = B;\
  2986 }
  2987 
  2988 /* Unlink a chunk from a smallbin  */
  2989 #define unlink_small_chunk(M, P, S) {\
  2990   mchunkptr F = P->fd;\
  2991   mchunkptr B = P->bk;\
  2992   bindex_t I = small_index(S);\
  2993   assert(P != B);\
  2994   assert(P != F);\
  2995   assert(chunksize(P) == small_index2size(I));\
  2996   if (F == B)\
  2997     clear_smallmap(M, I);\
  2998   else if (RTCHECK((F == smallbin_at(M,I) || ok_address(M, F)) &&\
  2999                    (B == smallbin_at(M,I) || ok_address(M, B)))) {\
  3000     F->bk = B;\
  3001     B->fd = F;\
  3002   }\
  3003   else {\
  3004     CORRUPTION_ERROR_ACTION(M);\
  3005   }\
  3006 }
  3007 
  3008 /* Unlink the first chunk from a smallbin */
  3009 #define unlink_first_small_chunk(M, B, P, I) {\
  3010   mchunkptr F = P->fd;\
  3011   assert(P != B);\
  3012   assert(P != F);\
  3013   assert(chunksize(P) == small_index2size(I));\
  3014   if (B == F)\
  3015     clear_smallmap(M, I);\
  3016   else if (RTCHECK(ok_address(M, F))) {\
  3017     B->fd = F;\
  3018     F->bk = B;\
  3019   }\
  3020   else {\
  3021     CORRUPTION_ERROR_ACTION(M);\
  3022   }\
  3023 }
  3024 
  3025 /* Replace dv node, binning the old one */
  3026 /* Used only when dvsize known to be small */
  3027 #define replace_dv(M, P, S) {\
  3028   size_t DVS = M->dvsize;\
  3029   if (DVS != 0) {\
  3030     mchunkptr DV = M->dv;\
  3031     assert(is_small(DVS));\
  3032     insert_small_chunk(M, DV, DVS);\
  3033   }\
  3034   M->dvsize = S;\
  3035   M->dv = P;\
  3036 }
  3037 
  3038 /* ------------------------- Operations on trees ------------------------- */
  3039 
  3040 /* Insert chunk into tree */
  3041 #define insert_large_chunk(M, X, S) {\
  3042   tbinptr* H;\
  3043   bindex_t I;\
  3044   compute_tree_index(S, I);\
  3045   H = treebin_at(M, I);\
  3046   X->index = I;\
  3047   X->child[0] = X->child[1] = 0;\
  3048   if (!treemap_is_marked(M, I)) {\
  3049     mark_treemap(M, I);\
  3050     *H = X;\
  3051     X->parent = (tchunkptr)H;\
  3052     X->fd = X->bk = X;\
  3053   }\
  3054   else {\
  3055     tchunkptr T = *H;\
  3056     size_t K = S << leftshift_for_tree_index(I);\
  3057     for (;;) {\
  3058       if (chunksize(T) != S) {\
  3059         tchunkptr* C = &(T->child[(K >> (SIZE_T_BITSIZE-SIZE_T_ONE)) & 1]);\
  3060         K <<= 1;\
  3061         if (*C != 0)\
  3062           T = *C;\
  3063         else if (RTCHECK(ok_address(M, C))) {\
  3064           *C = X;\
  3065           X->parent = T;\
  3066           X->fd = X->bk = X;\
  3067           break;\
  3068         }\
  3069         else {\
  3070           CORRUPTION_ERROR_ACTION(M);\
  3071           break;\
  3072         }\
  3073       }\
  3074       else {\
  3075         tchunkptr F = T->fd;\
  3076         if (RTCHECK(ok_address(M, T) && ok_address(M, F))) {\
  3077           T->fd = F->bk = X;\
  3078           X->fd = F;\
  3079           X->bk = T;\
  3080           X->parent = 0;\
  3081           break;\
  3082         }\
  3083         else {\
  3084           CORRUPTION_ERROR_ACTION(M);\
  3085           break;\
  3086         }\
  3087       }\
  3088     }\
  3089   }\
  3090 }
  3091 
  3092 /*
  3093   Unlink steps:
  3094 
  3095   1. If x is a chained node, unlink it from its same-sized fd/bk links
  3096      and choose its bk node as its replacement.
  3097   2. If x was the last node of its size, but not a leaf node, it must
  3098      be replaced with a leaf node (not merely one with an open left or
  3099      right), to make sure that lefts and rights of descendents
  3100      correspond properly to bit masks.  We use the rightmost descendent
  3101      of x.  We could use any other leaf, but this is easy to locate and
  3102      tends to counteract removal of leftmosts elsewhere, and so keeps
  3103      paths shorter than minimally guaranteed.  This doesn't loop much
  3104      because on average a node in a tree is near the bottom.
  3105   3. If x is the base of a chain (i.e., has parent links) relink
  3106      x's parent and children to x's replacement (or null if none).
  3107 */
  3108 
  3109 #define unlink_large_chunk(M, X) {\
  3110   tchunkptr XP = X->parent;\
  3111   tchunkptr R;\
  3112   if (X->bk != X) {\
  3113     tchunkptr F = X->fd;\
  3114     R = X->bk;\
  3115     if (RTCHECK(ok_address(M, F))) {\
  3116       F->bk = R;\
  3117       R->fd = F;\
  3118     }\
  3119     else {\
  3120       CORRUPTION_ERROR_ACTION(M);\
  3121     }\
  3122   }\
  3123   else {\
  3124     tchunkptr* RP;\
  3125     if (((R = *(RP = &(X->child[1]))) != 0) ||\
  3126         ((R = *(RP = &(X->child[0]))) != 0)) {\
  3127       tchunkptr* CP;\
  3128       while ((*(CP = &(R->child[1])) != 0) ||\
  3129              (*(CP = &(R->child[0])) != 0)) {\
  3130         R = *(RP = CP);\
  3131       }\
  3132       if (RTCHECK(ok_address(M, RP)))\
  3133         *RP = 0;\
  3134       else {\
  3135         CORRUPTION_ERROR_ACTION(M);\
  3136       }\
  3137     }\
  3138   }\
  3139   if (XP != 0) {\
  3140     tbinptr* H = treebin_at(M, X->index);\
  3141     if (X == *H) {\
  3142       if ((*H = R) == 0) \
  3143         clear_treemap(M, X->index);\
  3144     }\
  3145     else if (RTCHECK(ok_address(M, XP))) {\
  3146       if (XP->child[0] == X) \
  3147         XP->child[0] = R;\
  3148       else \
  3149         XP->child[1] = R;\
  3150     }\
  3151     else\
  3152       CORRUPTION_ERROR_ACTION(M);\
  3153     if (R != 0) {\
  3154       if (RTCHECK(ok_address(M, R))) {\
  3155         tchunkptr C0, C1;\
  3156         R->parent = XP;\
  3157         if ((C0 = X->child[0]) != 0) {\
  3158           if (RTCHECK(ok_address(M, C0))) {\
  3159             R->child[0] = C0;\
  3160             C0->parent = R;\
  3161           }\
  3162           else\
  3163             CORRUPTION_ERROR_ACTION(M);\
  3164         }\
  3165         if ((C1 = X->child[1]) != 0) {\
  3166           if (RTCHECK(ok_address(M, C1))) {\
  3167             R->child[1] = C1;\
  3168             C1->parent = R;\
  3169           }\
  3170           else\
  3171             CORRUPTION_ERROR_ACTION(M);\
  3172         }\
  3173       }\
  3174       else\
  3175         CORRUPTION_ERROR_ACTION(M);\
  3176     }\
  3177   }\
  3178 }
  3179 
  3180 /* Relays to large vs small bin operations */
  3181 
  3182 #define insert_chunk(M, P, S)\
  3183   if (is_small(S)) insert_small_chunk(M, P, S)\
  3184   else { tchunkptr TP = (tchunkptr)(P); insert_large_chunk(M, TP, S); }
  3185 
  3186 #define unlink_chunk(M, P, S)\
  3187   if (is_small(S)) unlink_small_chunk(M, P, S)\
  3188   else { tchunkptr TP = (tchunkptr)(P); unlink_large_chunk(M, TP); }
  3189 
  3190 
  3191 /* Relays to internal calls to malloc/free from realloc, memalign etc */
  3192 
  3193 #if ONLY_MSPACES
  3194 #define internal_malloc(m, b) mspace_malloc(m, b)
  3195 #define internal_free(m, mem) mspace_free(m,mem);
  3196 #else /* ONLY_MSPACES */
  3197 #if MSPACES
  3198 #define internal_malloc(m, b)\
  3199    (m == gm)? dlmalloc(b) : mspace_malloc(m, b)
  3200 #define internal_free(m, mem)\
  3201    if (m == gm) dlfree(mem); else mspace_free(m,mem);
  3202 #else /* MSPACES */
  3203 #define internal_malloc(m, b) dlmalloc(b)
  3204 #define internal_free(m, mem) dlfree(mem)
  3205 #endif /* MSPACES */
  3206 #endif /* ONLY_MSPACES */
  3207 
  3208 /* -----------------------  Direct-mmapping chunks ----------------------- */
  3209 
  3210 /*
  3211   Directly mmapped chunks are set up with an offset to the start of
  3212   the mmapped region stored in the prev_foot field of the chunk. This
  3213   allows reconstruction of the required argument to MUNMAP when freed,
  3214   and also allows adjustment of the returned chunk to meet alignment
  3215   requirements (especially in memalign).  There is also enough space
  3216   allocated to hold a fake next chunk of size SIZE_T_SIZE to maintain
  3217   the PINUSE bit so frees can be checked.
  3218 */
  3219 
  3220 /* Malloc using mmap */
  3221 static void *
  3222 mmap_alloc (mstate m, size_t nb)
  3223 {
  3224     size_t mmsize =
  3225         granularity_align (nb + SIX_SIZE_T_SIZES + CHUNK_ALIGN_MASK);
  3226     if (mmsize > nb) {          /* Check for wrap around 0 */
  3227         char *mm = (char *) (DIRECT_MMAP (mmsize));
  3228         if (mm != CMFAIL) {
  3229             size_t offset = align_offset (chunk2mem (mm));
  3230             size_t psize = mmsize - offset - MMAP_FOOT_PAD;
  3231             mchunkptr p = (mchunkptr) (mm + offset);
  3232             p->prev_foot = offset | IS_MMAPPED_BIT;
  3233             (p)->head = (psize | CINUSE_BIT);
  3234             mark_inuse_foot (m, p, psize);
  3235             chunk_plus_offset (p, psize)->head = FENCEPOST_HEAD;
  3236             chunk_plus_offset (p, psize + SIZE_T_SIZE)->head = 0;
  3237 
  3238             if (mm < m->least_addr)
  3239                 m->least_addr = mm;
  3240             if ((m->footprint += mmsize) > m->max_footprint)
  3241                 m->max_footprint = m->footprint;
  3242             assert (is_aligned (chunk2mem (p)));
  3243             check_mmapped_chunk (m, p);
  3244             return chunk2mem (p);
  3245         }
  3246     }
  3247     return 0;
  3248 }
  3249 
  3250 /* Realloc using mmap */
  3251 static mchunkptr
  3252 mmap_resize (mstate m, mchunkptr oldp, size_t nb)
  3253 {
  3254     size_t oldsize = chunksize (oldp);
  3255     if (is_small (nb))          /* Can't shrink mmap regions below small size */
  3256         return 0;
  3257     /* Keep old chunk if big enough but not too big */
  3258     if (oldsize >= nb + SIZE_T_SIZE &&
  3259         (oldsize - nb) <= (mparams.granularity << 1))
  3260         return oldp;
  3261     else {
  3262         size_t offset = oldp->prev_foot & ~IS_MMAPPED_BIT;
  3263         size_t oldmmsize = oldsize + offset + MMAP_FOOT_PAD;
  3264         size_t newmmsize = granularity_align (nb + SIX_SIZE_T_SIZES +
  3265                                               CHUNK_ALIGN_MASK);
  3266         char *cp = (char *) CALL_MREMAP ((char *) oldp - offset,
  3267                                          oldmmsize, newmmsize, 1);
  3268         if (cp != CMFAIL) {
  3269             mchunkptr newp = (mchunkptr) (cp + offset);
  3270             size_t psize = newmmsize - offset - MMAP_FOOT_PAD;
  3271             newp->head = (psize | CINUSE_BIT);
  3272             mark_inuse_foot (m, newp, psize);
  3273             chunk_plus_offset (newp, psize)->head = FENCEPOST_HEAD;
  3274             chunk_plus_offset (newp, psize + SIZE_T_SIZE)->head = 0;
  3275 
  3276             if (cp < m->least_addr)
  3277                 m->least_addr = cp;
  3278             if ((m->footprint += newmmsize - oldmmsize) > m->max_footprint)
  3279                 m->max_footprint = m->footprint;
  3280             check_mmapped_chunk (m, newp);
  3281             return newp;
  3282         }
  3283     }
  3284     return 0;
  3285 }
  3286 
  3287 /* -------------------------- mspace management -------------------------- */
  3288 
  3289 /* Initialize top chunk and its size */
  3290 static void
  3291 init_top (mstate m, mchunkptr p, size_t psize)
  3292 {
  3293     /* Ensure alignment */
  3294     size_t offset = align_offset (chunk2mem (p));
  3295     p = (mchunkptr) ((char *) p + offset);
  3296     psize -= offset;
  3297 
  3298     m->top = p;
  3299     m->topsize = psize;
  3300     p->head = psize | PINUSE_BIT;
  3301     /* set size of fake trailing chunk holding overhead space only once */
  3302     chunk_plus_offset (p, psize)->head = TOP_FOOT_SIZE;
  3303     m->trim_check = mparams.trim_threshold;     /* reset on each update */
  3304 }
  3305 
  3306 /* Initialize bins for a new mstate that is otherwise zeroed out */
  3307 static void
  3308 init_bins (mstate m)
  3309 {
  3310     /* Establish circular links for smallbins */
  3311     bindex_t i;
  3312     for (i = 0; i < NSMALLBINS; ++i) {
  3313         sbinptr bin = smallbin_at (m, i);
  3314         bin->fd = bin->bk = bin;
  3315     }
  3316 }
  3317 
  3318 #if PROCEED_ON_ERROR
  3319 
  3320 /* default corruption action */
  3321 static void
  3322 reset_on_error (mstate m)
  3323 {
  3324     int i;
  3325     ++malloc_corruption_error_count;
  3326     /* Reinitialize fields to forget about all memory */
  3327     m->smallbins = m->treebins = 0;
  3328     m->dvsize = m->topsize = 0;
  3329     m->seg.base = 0;
  3330     m->seg.size = 0;
  3331     m->seg.next = 0;
  3332     m->top = m->dv = 0;
  3333     for (i = 0; i < NTREEBINS; ++i)
  3334         *treebin_at (m, i) = 0;
  3335     init_bins (m);
  3336 }
  3337 #endif /* PROCEED_ON_ERROR */
  3338 
  3339 /* Allocate chunk and prepend remainder with chunk in successor base. */
  3340 static void *
  3341 prepend_alloc (mstate m, char *newbase, char *oldbase, size_t nb)
  3342 {
  3343     mchunkptr p = align_as_chunk (newbase);
  3344     mchunkptr oldfirst = align_as_chunk (oldbase);
  3345     size_t psize = (char *) oldfirst - (char *) p;
  3346     mchunkptr q = chunk_plus_offset (p, nb);
  3347     size_t qsize = psize - nb;
  3348     set_size_and_pinuse_of_inuse_chunk (m, p, nb);
  3349 
  3350     assert ((char *) oldfirst > (char *) q);
  3351     assert (pinuse (oldfirst));
  3352     assert (qsize >= MIN_CHUNK_SIZE);
  3353 
  3354     /* consolidate remainder with first chunk of old base */
  3355     if (oldfirst == m->top) {
  3356         size_t tsize = m->topsize += qsize;
  3357         m->top = q;
  3358         q->head = tsize | PINUSE_BIT;
  3359         check_top_chunk (m, q);
  3360     } else if (oldfirst == m->dv) {
  3361         size_t dsize = m->dvsize += qsize;
  3362         m->dv = q;
  3363         set_size_and_pinuse_of_free_chunk (q, dsize);
  3364     } else {
  3365         if (!cinuse (oldfirst)) {
  3366             size_t nsize = chunksize (oldfirst);
  3367             unlink_chunk (m, oldfirst, nsize);
  3368             oldfirst = chunk_plus_offset (oldfirst, nsize);
  3369             qsize += nsize;
  3370         }
  3371         set_free_with_pinuse (q, qsize, oldfirst);
  3372         insert_chunk (m, q, qsize);
  3373         check_free_chunk (m, q);
  3374     }
  3375 
  3376     check_malloced_chunk (m, chunk2mem (p), nb);
  3377     return chunk2mem (p);
  3378 }
  3379 
  3380 
  3381 /* Add a segment to hold a new noncontiguous region */
  3382 static void
  3383 add_segment (mstate m, char *tbase, size_t tsize, flag_t mmapped)
  3384 {
  3385     /* Determine locations and sizes of segment, fenceposts, old top */
  3386     char *old_top = (char *) m->top;
  3387     msegmentptr oldsp = segment_holding (m, old_top);
  3388     char *old_end = oldsp->base + oldsp->size;
  3389     size_t ssize = pad_request (sizeof (struct malloc_segment));
  3390     char *rawsp = old_end - (ssize + FOUR_SIZE_T_SIZES + CHUNK_ALIGN_MASK);
  3391     size_t offset = align_offset (chunk2mem (rawsp));
  3392     char *asp = rawsp + offset;
  3393     char *csp = (asp < (old_top + MIN_CHUNK_SIZE)) ? old_top : asp;
  3394     mchunkptr sp = (mchunkptr) csp;
  3395     msegmentptr ss = (msegmentptr) (chunk2mem (sp));
  3396     mchunkptr tnext = chunk_plus_offset (sp, ssize);
  3397     mchunkptr p = tnext;
  3398     int nfences = 0;
  3399 
  3400     /* reset top to new space */
  3401     init_top (m, (mchunkptr) tbase, tsize - TOP_FOOT_SIZE);
  3402 
  3403     /* Set up segment record */
  3404     assert (is_aligned (ss));
  3405     set_size_and_pinuse_of_inuse_chunk (m, sp, ssize);
  3406     *ss = m->seg;               /* Push current record */
  3407     m->seg.base = tbase;
  3408     m->seg.size = tsize;
  3409     m->seg.sflags = mmapped;
  3410     m->seg.next = ss;
  3411 
  3412     /* Insert trailing fenceposts */
  3413     for (;;) {
  3414         mchunkptr nextp = chunk_plus_offset (p, SIZE_T_SIZE);
  3415         p->head = FENCEPOST_HEAD;
  3416         ++nfences;
  3417         if ((char *) (&(nextp->head)) < old_end)
  3418             p = nextp;
  3419         else
  3420             break;
  3421     }
  3422     assert (nfences >= 2);
  3423 
  3424     /* Insert the rest of old top into a bin as an ordinary free chunk */
  3425     if (csp != old_top) {
  3426         mchunkptr q = (mchunkptr) old_top;
  3427         size_t psize = csp - old_top;
  3428         mchunkptr tn = chunk_plus_offset (q, psize);
  3429         set_free_with_pinuse (q, psize, tn);
  3430         insert_chunk (m, q, psize);
  3431     }
  3432 
  3433     check_top_chunk (m, m->top);
  3434 }
  3435 
  3436 /* -------------------------- System allocation -------------------------- */
  3437 
  3438 /* Get memory from system using MORECORE or MMAP */
  3439 static void *
  3440 sys_alloc (mstate m, size_t nb)
  3441 {
  3442     char *tbase = CMFAIL;
  3443     size_t tsize = 0;
  3444     flag_t mmap_flag = 0;
  3445 
  3446     init_mparams ();
  3447 
  3448     /* Directly map large chunks */
  3449     if (use_mmap (m) && nb >= mparams.mmap_threshold) {
  3450         void *mem = mmap_alloc (m, nb);
  3451         if (mem != 0)
  3452             return mem;
  3453     }
  3454 
  3455     /*
  3456        Try getting memory in any of three ways (in most-preferred to
  3457        least-preferred order):
  3458        1. A call to MORECORE that can normally contiguously extend memory.
  3459        (disabled if not MORECORE_CONTIGUOUS or not HAVE_MORECORE or
  3460        or main space is mmapped or a previous contiguous call failed)
  3461        2. A call to MMAP new space (disabled if not HAVE_MMAP).
  3462        Note that under the default settings, if MORECORE is unable to
  3463        fulfill a request, and HAVE_MMAP is true, then mmap is
  3464        used as a noncontiguous system allocator. This is a useful backup
  3465        strategy for systems with holes in address spaces -- in this case
  3466        sbrk cannot contiguously expand the heap, but mmap may be able to
  3467        find space.
  3468        3. A call to MORECORE that cannot usually contiguously extend memory.
  3469        (disabled if not HAVE_MORECORE)
  3470      */
  3471 
  3472     if (MORECORE_CONTIGUOUS && !use_noncontiguous (m)) {
  3473         char *br = CMFAIL;
  3474         msegmentptr ss =
  3475             (m->top == 0) ? 0 : segment_holding (m, (char *) m->top);
  3476         size_t asize = 0;
  3477         ACQUIRE_MORECORE_LOCK ();
  3478 
  3479         if (ss == 0) {          /* First time through or recovery */
  3480             char *base = (char *) CALL_MORECORE (0);
  3481             if (base != CMFAIL) {
  3482                 asize = granularity_align (nb + TOP_FOOT_SIZE + SIZE_T_ONE);
  3483                 /* Adjust to end on a page boundary */
  3484                 if (!is_page_aligned (base))
  3485                     asize += (page_align ((size_t) base) - (size_t) base);
  3486                 /* Can't call MORECORE if size is negative when treated as signed */
  3487                 if (asize < HALF_MAX_SIZE_T &&
  3488                     (br = (char *) (CALL_MORECORE (asize))) == base) {
  3489                     tbase = base;
  3490                     tsize = asize;
  3491                 }
  3492             }
  3493         } else {
  3494             /* Subtract out existing available top space from MORECORE request. */
  3495             asize =
  3496                 granularity_align (nb - m->topsize + TOP_FOOT_SIZE +
  3497                                    SIZE_T_ONE);
  3498             /* Use mem here only if it did continuously extend old space */
  3499             if (asize < HALF_MAX_SIZE_T &&
  3500                 (br =
  3501                  (char *) (CALL_MORECORE (asize))) == ss->base + ss->size) {
  3502                 tbase = br;
  3503                 tsize = asize;
  3504             }
  3505         }
  3506 
  3507         if (tbase == CMFAIL) {  /* Cope with partial failure */
  3508             if (br != CMFAIL) { /* Try to use/extend the space we did get */
  3509                 if (asize < HALF_MAX_SIZE_T &&
  3510                     asize < nb + TOP_FOOT_SIZE + SIZE_T_ONE) {
  3511                     size_t esize =
  3512                         granularity_align (nb + TOP_FOOT_SIZE +
  3513                                            SIZE_T_ONE - asize);
  3514                     if (esize < HALF_MAX_SIZE_T) {
  3515                         char *end = (char *) CALL_MORECORE (esize);
  3516                         if (end != CMFAIL)
  3517                             asize += esize;
  3518                         else {  /* Can't use; try to release */
  3519                             end = (char *) CALL_MORECORE (-asize);
  3520                             br = CMFAIL;
  3521                         }
  3522                     }
  3523                 }
  3524             }
  3525             if (br != CMFAIL) { /* Use the space we did get */
  3526                 tbase = br;
  3527                 tsize = asize;
  3528             } else
  3529                 disable_contiguous (m); /* Don't try contiguous path in the future */
  3530         }
  3531 
  3532         RELEASE_MORECORE_LOCK ();
  3533     }
  3534 
  3535     if (HAVE_MMAP && tbase == CMFAIL) { /* Try MMAP */
  3536         size_t req = nb + TOP_FOOT_SIZE + SIZE_T_ONE;
  3537         size_t rsize = granularity_align (req);
  3538         if (rsize > nb) {       /* Fail if wraps around zero */
  3539             char *mp = (char *) (CALL_MMAP (rsize));
  3540             if (mp != CMFAIL) {
  3541                 tbase = mp;
  3542                 tsize = rsize;
  3543                 mmap_flag = IS_MMAPPED_BIT;
  3544             }
  3545         }
  3546     }
  3547 
  3548     if (HAVE_MORECORE && tbase == CMFAIL) {     /* Try noncontiguous MORECORE */
  3549         size_t asize = granularity_align (nb + TOP_FOOT_SIZE + SIZE_T_ONE);
  3550         if (asize < HALF_MAX_SIZE_T) {
  3551             char *br = CMFAIL;
  3552             char *end = CMFAIL;
  3553             ACQUIRE_MORECORE_LOCK ();
  3554             br = (char *) (CALL_MORECORE (asize));
  3555             end = (char *) (CALL_MORECORE (0));
  3556             RELEASE_MORECORE_LOCK ();
  3557             if (br != CMFAIL && end != CMFAIL && br < end) {
  3558                 size_t ssize = end - br;
  3559                 if (ssize > nb + TOP_FOOT_SIZE) {
  3560                     tbase = br;
  3561                     tsize = ssize;
  3562                 }
  3563             }
  3564         }
  3565     }
  3566 
  3567     if (tbase != CMFAIL) {
  3568 
  3569         if ((m->footprint += tsize) > m->max_footprint)
  3570             m->max_footprint = m->footprint;
  3571 
  3572         if (!is_initialized (m)) {      /* first-time initialization */
  3573             m->seg.base = m->least_addr = tbase;
  3574             m->seg.size = tsize;
  3575             m->seg.sflags = mmap_flag;
  3576             m->magic = mparams.magic;
  3577             init_bins (m);
  3578             if (is_global (m))
  3579                 init_top (m, (mchunkptr) tbase, tsize - TOP_FOOT_SIZE);
  3580             else {
  3581                 /* Offset top by embedded malloc_state */
  3582                 mchunkptr mn = next_chunk (mem2chunk (m));
  3583                 init_top (m, mn,
  3584                           (size_t) ((tbase + tsize) - (char *) mn) -
  3585                           TOP_FOOT_SIZE);
  3586             }
  3587         }
  3588 
  3589         else {
  3590             /* Try to merge with an existing segment */
  3591             msegmentptr sp = &m->seg;
  3592             while (sp != 0 && tbase != sp->base + sp->size)
  3593                 sp = sp->next;
  3594             if (sp != 0 && !is_extern_segment (sp) && (sp->sflags & IS_MMAPPED_BIT) == mmap_flag && segment_holds (sp, m->top)) {       /* append */
  3595                 sp->size += tsize;
  3596                 init_top (m, m->top, m->topsize + tsize);
  3597             } else {
  3598                 if (tbase < m->least_addr)
  3599                     m->least_addr = tbase;
  3600                 sp = &m->seg;
  3601                 while (sp != 0 && sp->base != tbase + tsize)
  3602                     sp = sp->next;
  3603                 if (sp != 0 &&
  3604                     !is_extern_segment (sp) &&
  3605                     (sp->sflags & IS_MMAPPED_BIT) == mmap_flag) {
  3606                     char *oldbase = sp->base;
  3607                     sp->base = tbase;
  3608                     sp->size += tsize;
  3609                     return prepend_alloc (m, tbase, oldbase, nb);
  3610                 } else
  3611                     add_segment (m, tbase, tsize, mmap_flag);
  3612             }
  3613         }
  3614 
  3615         if (nb < m->topsize) {  /* Allocate from new or extended top space */
  3616             size_t rsize = m->topsize -= nb;
  3617             mchunkptr p = m->top;
  3618             mchunkptr r = m->top = chunk_plus_offset (p, nb);
  3619             r->head = rsize | PINUSE_BIT;
  3620             set_size_and_pinuse_of_inuse_chunk (m, p, nb);
  3621             check_top_chunk (m, m->top);
  3622             check_malloced_chunk (m, chunk2mem (p), nb);
  3623             return chunk2mem (p);
  3624         }
  3625     }
  3626 
  3627     MALLOC_FAILURE_ACTION;
  3628     return 0;
  3629 }
  3630 
  3631 /* -----------------------  system deallocation -------------------------- */
  3632 
  3633 /* Unmap and unlink any mmapped segments that don't contain used chunks */
  3634 static size_t
  3635 release_unused_segments (mstate m)
  3636 {
  3637     size_t released = 0;
  3638     msegmentptr pred = &m->seg;
  3639     msegmentptr sp = pred->next;
  3640     while (sp != 0) {
  3641         char *base = sp->base;
  3642         size_t size = sp->size;
  3643         msegmentptr next = sp->next;
  3644         if (is_mmapped_segment (sp) && !is_extern_segment (sp)) {
  3645             mchunkptr p = align_as_chunk (base);
  3646             size_t psize = chunksize (p);
  3647             /* Can unmap if first chunk holds entire segment and not pinned */
  3648             if (!cinuse (p)
  3649                 && (char *) p + psize >= base + size - TOP_FOOT_SIZE) {
  3650                 tchunkptr tp = (tchunkptr) p;
  3651                 assert (segment_holds (sp, (char *) sp));
  3652                 if (p == m->dv) {
  3653                     m->dv = 0;
  3654                     m->dvsize = 0;
  3655                 } else {
  3656                     unlink_large_chunk (m, tp);
  3657                 }
  3658                 if (CALL_MUNMAP (base, size) == 0) {
  3659                     released += size;
  3660                     m->footprint -= size;
  3661                     /* unlink obsoleted record */
  3662                     sp = pred;
  3663                     sp->next = next;
  3664                 } else {        /* back out if cannot unmap */
  3665                     insert_large_chunk (m, tp, psize);
  3666                 }
  3667             }
  3668         }
  3669         pred = sp;
  3670         sp = next;
  3671     }
  3672     return released;
  3673 }
  3674 
  3675 static int
  3676 sys_trim (mstate m, size_t pad)
  3677 {
  3678     size_t released = 0;
  3679     if (pad < MAX_REQUEST && is_initialized (m)) {
  3680         pad += TOP_FOOT_SIZE;   /* ensure enough room for segment overhead */
  3681 
  3682         if (m->topsize > pad) {
  3683             /* Shrink top space in granularity-size units, keeping at least one */
  3684             size_t unit = mparams.granularity;
  3685             size_t extra =
  3686                 ((m->topsize - pad + (unit - SIZE_T_ONE)) / unit -
  3687                  SIZE_T_ONE) * unit;
  3688             msegmentptr sp = segment_holding (m, (char *) m->top);
  3689 
  3690             if (!is_extern_segment (sp)) {
  3691                 if (is_mmapped_segment (sp)) {
  3692                     if (HAVE_MMAP && sp->size >= extra && !has_segment_link (m, sp)) {  /* can't shrink if pinned */
  3693                         size_t newsize = sp->size - extra;
  3694                         /* Prefer mremap, fall back to munmap */
  3695                         if ((CALL_MREMAP
  3696                              (sp->base, sp->size, newsize, 0) != MFAIL)
  3697                             || (CALL_MUNMAP (sp->base + newsize, extra)
  3698                                 == 0)) {
  3699                             released = extra;
  3700                         }
  3701                     }
  3702                 } else if (HAVE_MORECORE) {
  3703                     if (extra >= HALF_MAX_SIZE_T)       /* Avoid wrapping negative */
  3704                         extra = (HALF_MAX_SIZE_T) + SIZE_T_ONE - unit;
  3705                     ACQUIRE_MORECORE_LOCK ();
  3706                     {
  3707                         /* Make sure end of memory is where we last set it. */
  3708                         char *old_br = (char *) (CALL_MORECORE (0));
  3709                         if (old_br == sp->base + sp->size) {
  3710                             char *rel_br = (char *) (CALL_MORECORE (-extra));
  3711                             char *new_br = (char *) (CALL_MORECORE (0));
  3712                             if (rel_br != CMFAIL && new_br < old_br)
  3713                                 released = old_br - new_br;
  3714                         }
  3715                     }
  3716                     RELEASE_MORECORE_LOCK ();
  3717                 }
  3718             }
  3719 
  3720             if (released != 0) {
  3721                 sp->size -= released;
  3722                 m->footprint -= released;
  3723                 init_top (m, m->top, m->topsize - released);
  3724                 check_top_chunk (m, m->top);
  3725             }
  3726         }
  3727 
  3728         /* Unmap any unused mmapped segments */
  3729         if (HAVE_MMAP)
  3730             released += release_unused_segments (m);
  3731 
  3732         /* On failure, disable autotrim to avoid repeated failed future calls */
  3733         if (released == 0)
  3734             m->trim_check = MAX_SIZE_T;
  3735     }
  3736 
  3737     return (released != 0) ? 1 : 0;
  3738 }
  3739 
  3740 /* ---------------------------- malloc support --------------------------- */
  3741 
  3742 /* allocate a large request from the best fitting chunk in a treebin */
  3743 static void *
  3744 tmalloc_large (mstate m, size_t nb)
  3745 {
  3746     tchunkptr v = 0;
  3747     size_t rsize = -nb;         /* Unsigned negation */
  3748     tchunkptr t;
  3749     bindex_t idx;
  3750     compute_tree_index (nb, idx);
  3751 
  3752     if ((t = *treebin_at (m, idx)) != 0) {
  3753         /* Traverse tree for this bin looking for node with size == nb */
  3754         size_t sizebits = nb << leftshift_for_tree_index (idx);
  3755         tchunkptr rst = 0;      /* The deepest untaken right subtree */
  3756         for (;;) {
  3757             tchunkptr rt;
  3758             size_t trem = chunksize (t) - nb;
  3759             if (trem < rsize) {
  3760                 v = t;
  3761                 if ((rsize = trem) == 0)
  3762                     break;
  3763             }
  3764             rt = t->child[1];
  3765             t = t->child[(sizebits >> (SIZE_T_BITSIZE - SIZE_T_ONE)) & 1];
  3766             if (rt != 0 && rt != t)
  3767                 rst = rt;
  3768             if (t == 0) {
  3769                 t = rst;        /* set t to least subtree holding sizes > nb */
  3770                 break;
  3771             }
  3772             sizebits <<= 1;
  3773         }
  3774     }
  3775 
  3776     if (t == 0 && v == 0) {     /* set t to root of next non-empty treebin */
  3777         binmap_t leftbits = left_bits (idx2bit (idx)) & m->treemap;
  3778         if (leftbits != 0) {
  3779             bindex_t i;
  3780             binmap_t leastbit = least_bit (leftbits);
  3781             compute_bit2idx (leastbit, i);
  3782             t = *treebin_at (m, i);
  3783         }
  3784     }
  3785 
  3786     while (t != 0) {            /* find smallest of tree or subtree */
  3787         size_t trem = chunksize (t) - nb;
  3788         if (trem < rsize) {
  3789             rsize = trem;
  3790             v = t;
  3791         }
  3792         t = leftmost_child (t);
  3793     }
  3794 
  3795     /*  If dv is a better fit, return 0 so malloc will use it */
  3796     if (v != 0 && rsize < (size_t) (m->dvsize - nb)) {
  3797         if (RTCHECK (ok_address (m, v))) {      /* split */
  3798             mchunkptr r = chunk_plus_offset (v, nb);
  3799             assert (chunksize (v) == rsize + nb);
  3800             if (RTCHECK (ok_next (v, r))) {
  3801                 unlink_large_chunk (m, v);
  3802                 if (rsize < MIN_CHUNK_SIZE)
  3803                     set_inuse_and_pinuse (m, v, (rsize + nb));
  3804                 else {
  3805                     set_size_and_pinuse_of_inuse_chunk (m, v, nb);
  3806                     set_size_and_pinuse_of_free_chunk (r, rsize);
  3807                     insert_chunk (m, r, rsize);
  3808                 }
  3809                 return chunk2mem (v);
  3810             }
  3811         }
  3812         CORRUPTION_ERROR_ACTION (m);
  3813     }
  3814     return 0;
  3815 }
  3816 
  3817 /* allocate a small request from the best fitting chunk in a treebin */
  3818 static void *
  3819 tmalloc_small (mstate m, size_t nb)
  3820 {
  3821     tchunkptr t, v;
  3822     size_t rsize;
  3823     bindex_t i;
  3824     binmap_t leastbit = least_bit (m->treemap);
  3825     compute_bit2idx (leastbit, i);
  3826 
  3827     v = t = *treebin_at (m, i);
  3828     rsize = chunksize (t) - nb;
  3829 
  3830     while ((t = leftmost_child (t)) != 0) {
  3831         size_t trem = chunksize (t) - nb;
  3832         if (trem < rsize) {
  3833             rsize = trem;
  3834             v = t;
  3835         }
  3836     }
  3837 
  3838     if (RTCHECK (ok_address (m, v))) {
  3839         mchunkptr r = chunk_plus_offset (v, nb);
  3840         assert (chunksize (v) == rsize + nb);
  3841         if (RTCHECK (ok_next (v, r))) {
  3842             unlink_large_chunk (m, v);
  3843             if (rsize < MIN_CHUNK_SIZE)
  3844                 set_inuse_and_pinuse (m, v, (rsize + nb));
  3845             else {
  3846                 set_size_and_pinuse_of_inuse_chunk (m, v, nb);
  3847                 set_size_and_pinuse_of_free_chunk (r, rsize);
  3848                 replace_dv (m, r, rsize);
  3849             }
  3850             return chunk2mem (v);
  3851         }
  3852     }
  3853 
  3854     CORRUPTION_ERROR_ACTION (m);
  3855     return 0;
  3856 }
  3857 
  3858 /* --------------------------- realloc support --------------------------- */
  3859 
  3860 static void *
  3861 internal_realloc (mstate m, void *oldmem, size_t bytes)
  3862 {
  3863     if (bytes >= MAX_REQUEST) {
  3864         MALLOC_FAILURE_ACTION;
  3865         return 0;
  3866     }
  3867     if (!PREACTION (m)) {
  3868         mchunkptr oldp = mem2chunk (oldmem);
  3869         size_t oldsize = chunksize (oldp);
  3870         mchunkptr next = chunk_plus_offset (oldp, oldsize);
  3871         mchunkptr newp = 0;
  3872         void *extra = 0;
  3873 
  3874         /* Try to either shrink or extend into top. Else malloc-copy-free */
  3875 
  3876         if (RTCHECK (ok_address (m, oldp) && ok_cinuse (oldp) &&
  3877                      ok_next (oldp, next) && ok_pinuse (next))) {
  3878             size_t nb = request2size (bytes);
  3879             if (is_mmapped (oldp))
  3880                 newp = mmap_resize (m, oldp, nb);
  3881             else if (oldsize >= nb) {   /* already big enough */
  3882                 size_t rsize = oldsize - nb;
  3883                 newp = oldp;
  3884                 if (rsize >= MIN_CHUNK_SIZE) {
  3885                     mchunkptr remainder = chunk_plus_offset (newp, nb);
  3886                     set_inuse (m, newp, nb);
  3887                     set_inuse (m, remainder, rsize);
  3888                     extra = chunk2mem (remainder);
  3889                 }
  3890             } else if (next == m->top && oldsize + m->topsize > nb) {
  3891                 /* Expand into top */
  3892                 size_t newsize = oldsize + m->topsize;
  3893                 size_t newtopsize = newsize - nb;
  3894                 mchunkptr newtop = chunk_plus_offset (oldp, nb);
  3895                 set_inuse (m, oldp, nb);
  3896                 newtop->head = newtopsize | PINUSE_BIT;
  3897                 m->top = newtop;
  3898                 m->topsize = newtopsize;
  3899                 newp = oldp;
  3900             }
  3901         } else {
  3902             USAGE_ERROR_ACTION (m, oldmem);
  3903             POSTACTION (m);
  3904             return 0;
  3905         }
  3906 
  3907         POSTACTION (m);
  3908 
  3909         if (newp != 0) {
  3910             if (extra != 0) {
  3911                 internal_free (m, extra);
  3912             }
  3913             check_inuse_chunk (m, newp);
  3914             return chunk2mem (newp);
  3915         } else {
  3916             void *newmem = internal_malloc (m, bytes);
  3917             if (newmem != 0) {
  3918                 size_t oc = oldsize - overhead_for (oldp);
  3919                 memcpy (newmem, oldmem, (oc < bytes) ? oc : bytes);
  3920                 internal_free (m, oldmem);
  3921             }
  3922             return newmem;
  3923         }
  3924     }
  3925     return 0;
  3926 }
  3927 
  3928 /* --------------------------- memalign support -------------------------- */
  3929 
  3930 static void *
  3931 internal_memalign (mstate m, size_t alignment, size_t bytes)
  3932 {
  3933     if (alignment <= MALLOC_ALIGNMENT)  /* Can just use malloc */
  3934         return internal_malloc (m, bytes);
  3935     if (alignment < MIN_CHUNK_SIZE)     /* must be at least a minimum chunk size */
  3936         alignment = MIN_CHUNK_SIZE;
  3937     if ((alignment & (alignment - SIZE_T_ONE)) != 0) {  /* Ensure a power of 2 */
  3938         size_t a = MALLOC_ALIGNMENT << 1;
  3939         while (a < alignment)
  3940             a <<= 1;
  3941         alignment = a;
  3942     }
  3943 
  3944     if (bytes >= MAX_REQUEST - alignment) {
  3945         if (m != 0) {           /* Test isn't needed but avoids compiler warning */
  3946             MALLOC_FAILURE_ACTION;
  3947         }
  3948     } else {
  3949         size_t nb = request2size (bytes);
  3950         size_t req = nb + alignment + MIN_CHUNK_SIZE - CHUNK_OVERHEAD;
  3951         char *mem = (char *) internal_malloc (m, req);
  3952         if (mem != 0) {
  3953             void *leader = 0;
  3954             void *trailer = 0;
  3955             mchunkptr p = mem2chunk (mem);
  3956 
  3957             if (PREACTION (m))
  3958                 return 0;
  3959             if ((((size_t) (mem)) % alignment) != 0) {  /* misaligned */
  3960                 /*
  3961                    Find an aligned spot inside chunk.  Since we need to give
  3962                    back leading space in a chunk of at least MIN_CHUNK_SIZE, if
  3963                    the first calculation places us at a spot with less than
  3964                    MIN_CHUNK_SIZE leader, we can move to the next aligned spot.
  3965                    We've allocated enough total room so that this is always
  3966                    possible.
  3967                  */
  3968                 char *br = (char *)
  3969                     mem2chunk ((size_t)
  3970                                (((size_t)
  3971                                  (mem + alignment -
  3972                                   SIZE_T_ONE)) & -alignment));
  3973                 char *pos =
  3974                     ((size_t) (br - (char *) (p)) >=
  3975                      MIN_CHUNK_SIZE) ? br : br + alignment;
  3976                 mchunkptr newp = (mchunkptr) pos;
  3977                 size_t leadsize = pos - (char *) (p);
  3978                 size_t newsize = chunksize (p) - leadsize;
  3979 
  3980                 if (is_mmapped (p)) {   /* For mmapped chunks, just adjust offset */
  3981                     newp->prev_foot = p->prev_foot + leadsize;
  3982                     newp->head = (newsize | CINUSE_BIT);
  3983                 } else {        /* Otherwise, give back leader, use the rest */
  3984                     set_inuse (m, newp, newsize);
  3985                     set_inuse (m, p, leadsize);
  3986                     leader = chunk2mem (p);
  3987                 }
  3988                 p = newp;
  3989             }
  3990 
  3991             /* Give back spare room at the end */
  3992             if (!is_mmapped (p)) {
  3993                 size_t size = chunksize (p);
  3994                 if (size > nb + MIN_CHUNK_SIZE) {
  3995                     size_t remainder_size = size - nb;
  3996                     mchunkptr remainder = chunk_plus_offset (p, nb);
  3997                     set_inuse (m, p, nb);
  3998                     set_inuse (m, remainder, remainder_size);
  3999                     trailer = chunk2mem (remainder);
  4000                 }
  4001             }
  4002 
  4003             assert (chunksize (p) >= nb);
  4004             assert ((((size_t) (chunk2mem (p))) % alignment) == 0);
  4005             check_inuse_chunk (m, p);
  4006             POSTACTION (m);
  4007             if (leader != 0) {
  4008                 internal_free (m, leader);
  4009             }
  4010             if (trailer != 0) {
  4011                 internal_free (m, trailer);
  4012             }
  4013             return chunk2mem (p);
  4014         }
  4015     }
  4016     return 0;
  4017 }
  4018 
  4019 /* ------------------------ comalloc/coalloc support --------------------- */
  4020 
  4021 static void **
  4022 ialloc (mstate m, size_t n_elements, size_t * sizes, int opts, void *chunks[])
  4023 {
  4024     /*
  4025        This provides common support for independent_X routines, handling
  4026        all of the combinations that can result.
  4027 
  4028        The opts arg has:
  4029        bit 0 set if all elements are same size (using sizes[0])
  4030        bit 1 set if elements should be zeroed
  4031      */
  4032 
  4033     size_t element_size;        /* chunksize of each element, if all same */
  4034     size_t contents_size;       /* total size of elements */
  4035     size_t array_size;          /* request size of pointer array */
  4036     void *mem;                  /* malloced aggregate space */
  4037     mchunkptr p;                /* corresponding chunk */
  4038     size_t remainder_size;      /* remaining bytes while splitting */
  4039     void **marray;              /* either "chunks" or malloced ptr array */
  4040     mchunkptr array_chunk;      /* chunk for malloced ptr array */
  4041     flag_t was_enabled;         /* to disable mmap */
  4042     size_t size;
  4043     size_t i;
  4044 
  4045     /* compute array length, if needed */
  4046     if (chunks != 0) {
  4047         if (n_elements == 0)
  4048             return chunks;      /* nothing to do */
  4049         marray = chunks;
  4050         array_size = 0;
  4051     } else {
  4052         /* if empty req, must still return chunk representing empty array */
  4053         if (n_elements == 0)
  4054             return (void **) internal_malloc (m, 0);
  4055         marray = 0;
  4056         array_size = request2size (n_elements * (sizeof (void *)));
  4057     }
  4058 
  4059     /* compute total element size */
  4060     if (opts & 0x1) {           /* all-same-size */
  4061         element_size = request2size (*sizes);
  4062         contents_size = n_elements * element_size;
  4063     } else {                    /* add up all the sizes */
  4064         element_size = 0;
  4065         contents_size = 0;
  4066         for (i = 0; i != n_elements; ++i)
  4067             contents_size += request2size (sizes[i]);
  4068     }
  4069 
  4070     size = contents_size + array_size;
  4071 
  4072     /*
  4073        Allocate the aggregate chunk.  First disable direct-mmapping so
  4074        malloc won't use it, since we would not be able to later
  4075        free/realloc space internal to a segregated mmap region.
  4076      */
  4077     was_enabled = use_mmap (m);
  4078     disable_mmap (m);
  4079     mem = internal_malloc (m, size - CHUNK_OVERHEAD);
  4080     if (was_enabled)
  4081         enable_mmap (m);
  4082     if (mem == 0)
  4083         return 0;
  4084 
  4085     if (PREACTION (m))
  4086         return 0;
  4087     p = mem2chunk (mem);
  4088     remainder_size = chunksize (p);
  4089 
  4090     assert (!is_mmapped (p));
  4091 
  4092     if (opts & 0x2) {           /* optionally clear the elements */
  4093         memset ((size_t *) mem, 0, remainder_size - SIZE_T_SIZE - array_size);
  4094     }
  4095 
  4096     /* If not provided, allocate the pointer array as final part of chunk */
  4097     if (marray == 0) {
  4098         size_t array_chunk_size;
  4099         array_chunk = chunk_plus_offset (p, contents_size);
  4100         array_chunk_size = remainder_size - contents_size;
  4101         marray = (void **) (chunk2mem (array_chunk));
  4102         set_size_and_pinuse_of_inuse_chunk (m, array_chunk, array_chunk_size);
  4103         remainder_size = contents_size;
  4104     }
  4105 
  4106     /* split out elements */
  4107     for (i = 0;; ++i) {
  4108         marray[i] = chunk2mem (p);
  4109         if (i != n_elements - 1) {
  4110             if (element_size != 0)
  4111                 size = element_size;
  4112             else
  4113                 size = request2size (sizes[i]);
  4114             remainder_size -= size;
  4115             set_size_and_pinuse_of_inuse_chunk (m, p, size);
  4116             p = chunk_plus_offset (p, size);
  4117         } else {                /* the final element absorbs any overallocation slop */
  4118             set_size_and_pinuse_of_inuse_chunk (m, p, remainder_size);
  4119             break;
  4120         }
  4121     }
  4122 
  4123 #if DEBUG
  4124     if (marray != chunks) {
  4125         /* final element must have exactly exhausted chunk */
  4126         if (element_size != 0) {
  4127             assert (remainder_size == element_size);
  4128         } else {
  4129             assert (remainder_size == request2size (sizes[i]));
  4130         }
  4131         check_inuse_chunk (m, mem2chunk (marray));
  4132     }
  4133     for (i = 0; i != n_elements; ++i)
  4134         check_inuse_chunk (m, mem2chunk (marray[i]));
  4135 
  4136 #endif /* DEBUG */
  4137 
  4138     POSTACTION (m);
  4139     return marray;
  4140 }
  4141 
  4142 
  4143 /* -------------------------- public routines ---------------------------- */
  4144 
  4145 #if !ONLY_MSPACES
  4146 
  4147 void *
  4148 dlmalloc (size_t bytes)
  4149 {
  4150     /*
  4151        Basic algorithm:
  4152        If a small request (< 256 bytes minus per-chunk overhead):
  4153        1. If one exists, use a remainderless chunk in associated smallbin.
  4154        (Remainderless means that there are too few excess bytes to
  4155        represent as a chunk.)
  4156        2. If it is big enough, use the dv chunk, which is normally the
  4157        chunk adjacent to the one used for the most recent small request.
  4158        3. If one exists, split the smallest available chunk in a bin,
  4159        saving remainder in dv.
  4160        4. If it is big enough, use the top chunk.
  4161        5. If available, get memory from system and use it
  4162        Otherwise, for a large request:
  4163        1. Find the smallest available binned chunk that fits, and use it
  4164        if it is better fitting than dv chunk, splitting if necessary.
  4165        2. If better fitting than any binned chunk, use the dv chunk.
  4166        3. If it is big enough, use the top chunk.
  4167        4. If request size >= mmap threshold, try to directly mmap this chunk.
  4168        5. If available, get memory from system and use it
  4169 
  4170        The ugly goto's here ensure that postaction occurs along all paths.
  4171      */
  4172 
  4173     if (!PREACTION (gm)) {
  4174         void *mem;
  4175         size_t nb;
  4176         if (bytes <= MAX_SMALL_REQUEST) {
  4177             bindex_t idx;
  4178             binmap_t smallbits;
  4179             nb = (bytes < MIN_REQUEST) ? MIN_CHUNK_SIZE : pad_request (bytes);
  4180             idx = small_index (nb);
  4181             smallbits = gm->smallmap >> idx;
  4182 
  4183             if ((smallbits & 0x3U) != 0) {      /* Remainderless fit to a smallbin. */
  4184                 mchunkptr b, p;
  4185                 idx += ~smallbits & 1;  /* Uses next bin if idx empty */
  4186                 b = smallbin_at (gm, idx);
  4187                 p = b->fd;
  4188                 assert (chunksize (p) == small_index2size (idx));
  4189                 unlink_first_small_chunk (gm, b, p, idx);
  4190                 set_inuse_and_pinuse (gm, p, small_index2size (idx));
  4191                 mem = chunk2mem (p);
  4192                 check_malloced_chunk (gm, mem, nb);
  4193                 goto postaction;
  4194             }
  4195 
  4196             else if (nb > gm->dvsize) {
  4197                 if (smallbits != 0) {   /* Use chunk in next nonempty smallbin */
  4198                     mchunkptr b, p, r;
  4199                     size_t rsize;
  4200                     bindex_t i;
  4201                     binmap_t leftbits =
  4202                         (smallbits << idx) & left_bits (idx2bit (idx));
  4203                     binmap_t leastbit = least_bit (leftbits);
  4204                     compute_bit2idx (leastbit, i);
  4205                     b = smallbin_at (gm, i);
  4206                     p = b->fd;
  4207                     assert (chunksize (p) == small_index2size (i));
  4208                     unlink_first_small_chunk (gm, b, p, i);
  4209                     rsize = small_index2size (i) - nb;
  4210                     /* Fit here cannot be remainderless if 4byte sizes */
  4211                     if (SIZE_T_SIZE != 4 && rsize < MIN_CHUNK_SIZE)
  4212                         set_inuse_and_pinuse (gm, p, small_index2size (i));
  4213                     else {
  4214                         set_size_and_pinuse_of_inuse_chunk (gm, p, nb);
  4215                         r = chunk_plus_offset (p, nb);
  4216                         set_size_and_pinuse_of_free_chunk (r, rsize);
  4217                         replace_dv (gm, r, rsize);
  4218                     }
  4219                     mem = chunk2mem (p);
  4220                     check_malloced_chunk (gm, mem, nb);
  4221                     goto postaction;
  4222                 }
  4223 
  4224                 else if (gm->treemap != 0
  4225                          && (mem = tmalloc_small (gm, nb)) != 0) {
  4226                     check_malloced_chunk (gm, mem, nb);
  4227                     goto postaction;
  4228                 }
  4229             }
  4230         } else if (bytes >= MAX_REQUEST)
  4231             nb = MAX_SIZE_T;    /* Too big to allocate. Force failure (in sys alloc) */
  4232         else {
  4233             nb = pad_request (bytes);
  4234             if (gm->treemap != 0 && (mem = tmalloc_large (gm, nb)) != 0) {
  4235                 check_malloced_chunk (gm, mem, nb);
  4236                 goto postaction;
  4237             }
  4238         }
  4239 
  4240         if (nb <= gm->dvsize) {
  4241             size_t rsize = gm->dvsize - nb;
  4242             mchunkptr p = gm->dv;
  4243             if (rsize >= MIN_CHUNK_SIZE) {      /* split dv */
  4244                 mchunkptr r = gm->dv = chunk_plus_offset (p, nb);
  4245                 gm->dvsize = rsize;
  4246                 set_size_and_pinuse_of_free_chunk (r, rsize);
  4247                 set_size_and_pinuse_of_inuse_chunk (gm, p, nb);
  4248             } else {            /* exhaust dv */
  4249                 size_t dvs = gm->dvsize;
  4250                 gm->dvsize = 0;
  4251                 gm->dv = 0;
  4252                 set_inuse_and_pinuse (gm, p, dvs);
  4253             }
  4254             mem = chunk2mem (p);
  4255             check_malloced_chunk (gm, mem, nb);
  4256             goto postaction;
  4257         }
  4258 
  4259         else if (nb < gm->topsize) {    /* Split top */
  4260             size_t rsize = gm->topsize -= nb;
  4261             mchunkptr p = gm->top;
  4262             mchunkptr r = gm->top = chunk_plus_offset (p, nb);
  4263             r->head = rsize | PINUSE_BIT;
  4264             set_size_and_pinuse_of_inuse_chunk (gm, p, nb);
  4265             mem = chunk2mem (p);
  4266             check_top_chunk (gm, gm->top);
  4267             check_malloced_chunk (gm, mem, nb);
  4268             goto postaction;
  4269         }
  4270 
  4271         mem = sys_alloc (gm, nb);
  4272 
  4273       postaction:
  4274         POSTACTION (gm);
  4275         return mem;
  4276     }
  4277 
  4278     return 0;
  4279 }
  4280 
  4281 void
  4282 dlfree (void *mem)
  4283 {
  4284     /*
  4285        Consolidate freed chunks with preceeding or succeeding bordering
  4286        free chunks, if they exist, and then place in a bin.  Intermixed
  4287        with special cases for top, dv, mmapped chunks, and usage errors.
  4288      */
  4289 
  4290     if (mem != 0) {
  4291         mchunkptr p = mem2chunk (mem);
  4292 #if FOOTERS
  4293         mstate fm = get_mstate_for (p);
  4294         if (!ok_magic (fm)) {
  4295             USAGE_ERROR_ACTION (fm, p);
  4296             return;
  4297         }
  4298 #else /* FOOTERS */
  4299 #define fm gm
  4300 #endif /* FOOTERS */
  4301         if (!PREACTION (fm)) {
  4302             check_inuse_chunk (fm, p);
  4303             if (RTCHECK (ok_address (fm, p) && ok_cinuse (p))) {
  4304                 size_t psize = chunksize (p);
  4305                 mchunkptr next = chunk_plus_offset (p, psize);
  4306                 if (!pinuse (p)) {
  4307                     size_t prevsize = p->prev_foot;
  4308                     if ((prevsize & IS_MMAPPED_BIT) != 0) {
  4309                         prevsize &= ~IS_MMAPPED_BIT;
  4310                         psize += prevsize + MMAP_FOOT_PAD;
  4311                         if (CALL_MUNMAP ((char *) p - prevsize, psize) == 0)
  4312                             fm->footprint -= psize;
  4313                         goto postaction;
  4314                     } else {
  4315                         mchunkptr prev = chunk_minus_offset (p, prevsize);
  4316                         psize += prevsize;
  4317                         p = prev;
  4318                         if (RTCHECK (ok_address (fm, prev))) {  /* consolidate backward */
  4319                             if (p != fm->dv) {
  4320                                 unlink_chunk (fm, p, prevsize);
  4321                             } else if ((next->head & INUSE_BITS) ==
  4322                                        INUSE_BITS) {
  4323                                 fm->dvsize = psize;
  4324                                 set_free_with_pinuse (p, psize, next);
  4325                                 goto postaction;
  4326                             }
  4327                         } else
  4328                             goto erroraction;
  4329                     }
  4330                 }
  4331 
  4332                 if (RTCHECK (ok_next (p, next) && ok_pinuse (next))) {
  4333                     if (!cinuse (next)) {       /* consolidate forward */
  4334                         if (next == fm->top) {
  4335                             size_t tsize = fm->topsize += psize;
  4336                             fm->top = p;
  4337                             p->head = tsize | PINUSE_BIT;
  4338                             if (p == fm->dv) {
  4339                                 fm->dv = 0;
  4340                                 fm->dvsize = 0;
  4341                             }
  4342                             if (should_trim (fm, tsize))
  4343                                 sys_trim (fm, 0);
  4344                             goto postaction;
  4345                         } else if (next == fm->dv) {
  4346                             size_t dsize = fm->dvsize += psize;
  4347                             fm->dv = p;
  4348                             set_size_and_pinuse_of_free_chunk (p, dsize);
  4349                             goto postaction;
  4350                         } else {
  4351                             size_t nsize = chunksize (next);
  4352                             psize += nsize;
  4353                             unlink_chunk (fm, next, nsize);
  4354                             set_size_and_pinuse_of_free_chunk (p, psize);
  4355                             if (p == fm->dv) {
  4356                                 fm->dvsize = psize;
  4357                                 goto postaction;
  4358                             }
  4359                         }
  4360                     } else
  4361                         set_free_with_pinuse (p, psize, next);
  4362                     insert_chunk (fm, p, psize);
  4363                     check_free_chunk (fm, p);
  4364                     goto postaction;
  4365                 }
  4366             }
  4367           erroraction:
  4368             USAGE_ERROR_ACTION (fm, p);
  4369           postaction:
  4370             POSTACTION (fm);
  4371         }
  4372     }
  4373 #if !FOOTERS
  4374 #undef fm
  4375 #endif /* FOOTERS */
  4376 }
  4377 
  4378 void *
  4379 dlcalloc (size_t n_elements, size_t elem_size)
  4380 {
  4381     void *mem;
  4382     size_t req = 0;
  4383     if (n_elements != 0) {
  4384         req = n_elements * elem_size;
  4385         if (((n_elements | elem_size) & ~(size_t) 0xffff) &&
  4386             (req / n_elements != elem_size))
  4387             req = MAX_SIZE_T;   /* force downstream failure on overflow */
  4388     }
  4389     mem = dlmalloc (req);
  4390     if (mem != 0 && calloc_must_clear (mem2chunk (mem)))
  4391         memset (mem, 0, req);
  4392     return mem;
  4393 }
  4394 
  4395 void *
  4396 dlrealloc (void *oldmem, size_t bytes)
  4397 {
  4398     if (oldmem == 0)
  4399         return dlmalloc (bytes);
  4400 #ifdef REALLOC_ZERO_BYTES_FREES
  4401     if (bytes == 0) {
  4402         dlfree (oldmem);
  4403         return 0;
  4404     }
  4405 #endif /* REALLOC_ZERO_BYTES_FREES */
  4406     else {
  4407 #if ! FOOTERS
  4408         mstate m = gm;
  4409 #else /* FOOTERS */
  4410         mstate m = get_mstate_for (mem2chunk (oldmem));
  4411         if (!ok_magic (m)) {
  4412             USAGE_ERROR_ACTION (m, oldmem);
  4413             return 0;
  4414         }
  4415 #endif /* FOOTERS */
  4416         return internal_realloc (m, oldmem, bytes);
  4417     }
  4418 }
  4419 
  4420 void *
  4421 dlmemalign (size_t alignment, size_t bytes)
  4422 {
  4423     return internal_memalign (gm, alignment, bytes);
  4424 }
  4425 
  4426 void **
  4427 dlindependent_calloc (size_t n_elements, size_t elem_size, void *chunks[])
  4428 {
  4429     size_t sz = elem_size;      /* serves as 1-element array */
  4430     return ialloc (gm, n_elements, &sz, 3, chunks);
  4431 }
  4432 
  4433 void **
  4434 dlindependent_comalloc (size_t n_elements, size_t sizes[], void *chunks[])
  4435 {
  4436     return ialloc (gm, n_elements, sizes, 0, chunks);
  4437 }
  4438 
  4439 void *
  4440 dlvalloc (size_t bytes)
  4441 {
  4442     size_t pagesz;
  4443     init_mparams ();
  4444     pagesz = mparams.page_size;
  4445     return dlmemalign (pagesz, bytes);
  4446 }
  4447 
  4448 void *
  4449 dlpvalloc (size_t bytes)
  4450 {
  4451     size_t pagesz;
  4452     init_mparams ();
  4453     pagesz = mparams.page_size;
  4454     return dlmemalign (pagesz,
  4455                        (bytes + pagesz - SIZE_T_ONE) & ~(pagesz -
  4456                                                          SIZE_T_ONE));
  4457 }
  4458 
  4459 int
  4460 dlmalloc_trim (size_t pad)
  4461 {
  4462     int result = 0;
  4463     if (!PREACTION (gm)) {
  4464         result = sys_trim (gm, pad);
  4465         POSTACTION (gm);
  4466     }
  4467     return result;
  4468 }
  4469 
  4470 size_t
  4471 dlmalloc_footprint (void)
  4472 {
  4473     return gm->footprint;
  4474 }
  4475 
  4476 size_t
  4477 dlmalloc_max_footprint (void)
  4478 {
  4479     return gm->max_footprint;
  4480 }
  4481 
  4482 #if !NO_MALLINFO
  4483 struct mallinfo
  4484 dlmallinfo (void)
  4485 {
  4486     return internal_mallinfo (gm);
  4487 }
  4488 #endif /* NO_MALLINFO */
  4489 
  4490 void
  4491 dlmalloc_stats ()
  4492 {
  4493     internal_malloc_stats (gm);
  4494 }
  4495 
  4496 size_t
  4497 dlmalloc_usable_size (void *mem)
  4498 {
  4499     if (mem != 0) {
  4500         mchunkptr p = mem2chunk (mem);
  4501         if (cinuse (p))
  4502             return chunksize (p) - overhead_for (p);
  4503     }
  4504     return 0;
  4505 }
  4506 
  4507 int
  4508 dlmallopt (int param_number, int value)
  4509 {
  4510     return change_mparam (param_number, value);
  4511 }
  4512 
  4513 #endif /* !ONLY_MSPACES */
  4514 
  4515 /* ----------------------------- user mspaces ---------------------------- */
  4516 
  4517 #if MSPACES
  4518 
  4519 static mstate
  4520 init_user_mstate (char *tbase, size_t tsize)
  4521 {
  4522     size_t msize = pad_request (sizeof (struct malloc_state));
  4523     mchunkptr mn;
  4524     mchunkptr msp = align_as_chunk (tbase);
  4525     mstate m = (mstate) (chunk2mem (msp));
  4526     memset (m, 0, msize);
  4527     INITIAL_LOCK (&m->mutex);
  4528     msp->head = (msize | PINUSE_BIT | CINUSE_BIT);
  4529     m->seg.base = m->least_addr = tbase;
  4530     m->seg.size = m->footprint = m->max_footprint = tsize;
  4531     m->magic = mparams.magic;
  4532     m->mflags = mparams.default_mflags;
  4533     disable_contiguous (m);
  4534     init_bins (m);
  4535     mn = next_chunk (mem2chunk (m));
  4536     init_top (m, mn,
  4537               (size_t) ((tbase + tsize) - (char *) mn) - TOP_FOOT_SIZE);
  4538     check_top_chunk (m, m->top);
  4539     return m;
  4540 }
  4541 
  4542 mspace
  4543 create_mspace (size_t capacity, int locked)
  4544 {
  4545     mstate m = 0;
  4546     size_t msize = pad_request (sizeof (struct malloc_state));
  4547     init_mparams ();            /* Ensure pagesize etc initialized */
  4548 
  4549     if (capacity < (size_t) - (msize + TOP_FOOT_SIZE + mparams.page_size)) {
  4550         size_t rs = ((capacity == 0) ? mparams.granularity :
  4551                      (capacity + TOP_FOOT_SIZE + msize));
  4552         size_t tsize = granularity_align (rs);
  4553         char *tbase = (char *) (CALL_MMAP (tsize));
  4554         if (tbase != CMFAIL) {
  4555             m = init_user_mstate (tbase, tsize);
  4556             m->seg.sflags = IS_MMAPPED_BIT;
  4557             set_lock (m, locked);
  4558         }
  4559     }
  4560     return (mspace) m;
  4561 }
  4562 
  4563 mspace
  4564 create_mspace_with_base (void *base, size_t capacity, int locked)
  4565 {
  4566     mstate m = 0;
  4567     size_t msize = pad_request (sizeof (struct malloc_state));
  4568     init_mparams ();            /* Ensure pagesize etc initialized */
  4569 
  4570     if (capacity > msize + TOP_FOOT_SIZE &&
  4571         capacity < (size_t) - (msize + TOP_FOOT_SIZE + mparams.page_size)) {
  4572         m = init_user_mstate ((char *) base, capacity);
  4573         m->seg.sflags = EXTERN_BIT;
  4574         set_lock (m, locked);
  4575     }
  4576     return (mspace) m;
  4577 }
  4578 
  4579 size_t
  4580 destroy_mspace (mspace msp)
  4581 {
  4582     size_t freed = 0;
  4583     mstate ms = (mstate) msp;
  4584     if (ok_magic (ms)) {
  4585         msegmentptr sp = &ms->seg;
  4586         while (sp != 0) {
  4587             char *base = sp->base;
  4588             size_t size = sp->size;
  4589             flag_t flag = sp->sflags;
  4590             sp = sp->next;
  4591             if ((flag & IS_MMAPPED_BIT) && !(flag & EXTERN_BIT) &&
  4592                 CALL_MUNMAP (base, size) == 0)
  4593                 freed += size;
  4594         }
  4595     } else {
  4596         USAGE_ERROR_ACTION (ms, ms);
  4597     }
  4598     return freed;
  4599 }
  4600 
  4601 /*
  4602   mspace versions of routines are near-clones of the global
  4603   versions. This is not so nice but better than the alternatives.
  4604 */
  4605 
  4606 
  4607 void *
  4608 mspace_malloc (mspace msp, size_t bytes)
  4609 {
  4610     mstate ms = (mstate) msp;
  4611     if (!ok_magic (ms)) {
  4612         USAGE_ERROR_ACTION (ms, ms);
  4613         return 0;
  4614     }
  4615     if (!PREACTION (ms)) {
  4616         void *mem;
  4617         size_t nb;
  4618         if (bytes <= MAX_SMALL_REQUEST) {
  4619             bindex_t idx;
  4620             binmap_t smallbits;
  4621             nb = (bytes < MIN_REQUEST) ? MIN_CHUNK_SIZE : pad_request (bytes);
  4622             idx = small_index (nb);
  4623             smallbits = ms->smallmap >> idx;
  4624 
  4625             if ((smallbits & 0x3U) != 0) {      /* Remainderless fit to a smallbin. */
  4626                 mchunkptr b, p;
  4627                 idx += ~smallbits & 1;  /* Uses next bin if idx empty */
  4628                 b = smallbin_at (ms, idx);
  4629                 p = b->fd;
  4630                 assert (chunksize (p) == small_index2size (idx));
  4631                 unlink_first_small_chunk (ms, b, p, idx);
  4632                 set_inuse_and_pinuse (ms, p, small_index2size (idx));
  4633                 mem = chunk2mem (p);
  4634                 check_malloced_chunk (ms, mem, nb);
  4635                 goto postaction;
  4636             }
  4637 
  4638             else if (nb > ms->dvsize) {
  4639                 if (smallbits != 0) {   /* Use chunk in next nonempty smallbin */
  4640                     mchunkptr b, p, r;
  4641                     size_t rsize;
  4642                     bindex_t i;
  4643                     binmap_t leftbits =
  4644                         (smallbits << idx) & left_bits (idx2bit (idx));
  4645                     binmap_t leastbit = least_bit (leftbits);
  4646                     compute_bit2idx (leastbit, i);
  4647                     b = smallbin_at (ms, i);
  4648                     p = b->fd;
  4649                     assert (chunksize (p) == small_index2size (i));
  4650                     unlink_first_small_chunk (ms, b, p, i);
  4651                     rsize = small_index2size (i) - nb;
  4652                     /* Fit here cannot be remainderless if 4byte sizes */
  4653                     if (SIZE_T_SIZE != 4 && rsize < MIN_CHUNK_SIZE)
  4654                         set_inuse_and_pinuse (ms, p, small_index2size (i));
  4655                     else {
  4656                         set_size_and_pinuse_of_inuse_chunk (ms, p, nb);
  4657                         r = chunk_plus_offset (p, nb);
  4658                         set_size_and_pinuse_of_free_chunk (r, rsize);
  4659                         replace_dv (ms, r, rsize);
  4660                     }
  4661                     mem = chunk2mem (p);
  4662                     check_malloced_chunk (ms, mem, nb);
  4663                     goto postaction;
  4664                 }
  4665 
  4666                 else if (ms->treemap != 0
  4667                          && (mem = tmalloc_small (ms, nb)) != 0) {
  4668                     check_malloced_chunk (ms, mem, nb);
  4669                     goto postaction;
  4670                 }
  4671             }
  4672         } else if (bytes >= MAX_REQUEST)
  4673             nb = MAX_SIZE_T;    /* Too big to allocate. Force failure (in sys alloc) */
  4674         else {
  4675             nb = pad_request (bytes);
  4676             if (ms->treemap != 0 && (mem = tmalloc_large (ms, nb)) != 0) {
  4677                 check_malloced_chunk (ms, mem, nb);
  4678                 goto postaction;
  4679             }
  4680         }
  4681 
  4682         if (nb <= ms->dvsize) {
  4683             size_t rsize = ms->dvsize - nb;
  4684             mchunkptr p = ms->dv;
  4685             if (rsize >= MIN_CHUNK_SIZE) {      /* split dv */
  4686                 mchunkptr r = ms->dv = chunk_plus_offset (p, nb);
  4687                 ms->dvsize = rsize;
  4688                 set_size_and_pinuse_of_free_chunk (r, rsize);
  4689                 set_size_and_pinuse_of_inuse_chunk (ms, p, nb);
  4690             } else {            /* exhaust dv */
  4691                 size_t dvs = ms->dvsize;
  4692                 ms->dvsize = 0;
  4693                 ms->dv = 0;
  4694                 set_inuse_and_pinuse (ms, p, dvs);
  4695             }
  4696             mem = chunk2mem (p);
  4697             check_malloced_chunk (ms, mem, nb);
  4698             goto postaction;
  4699         }
  4700 
  4701         else if (nb < ms->topsize) {    /* Split top */
  4702             size_t rsize = ms->topsize -= nb;
  4703             mchunkptr p = ms->top;
  4704             mchunkptr r = ms->top = chunk_plus_offset (p, nb);
  4705             r->head = rsize | PINUSE_BIT;
  4706             set_size_and_pinuse_of_inuse_chunk (ms, p, nb);
  4707             mem = chunk2mem (p);
  4708             check_top_chunk (ms, ms->top);
  4709             check_malloced_chunk (ms, mem, nb);
  4710             goto postaction;
  4711         }
  4712 
  4713         mem = sys_alloc (ms, nb);
  4714 
  4715       postaction:
  4716         POSTACTION (ms);
  4717         return mem;
  4718     }
  4719 
  4720     return 0;
  4721 }
  4722 
  4723 void
  4724 mspace_free (mspace msp, void *mem)
  4725 {
  4726     if (mem != 0) {
  4727         mchunkptr p = mem2chunk (mem);
  4728 #if FOOTERS
  4729         mstate fm = get_mstate_for (p);
  4730 #else /* FOOTERS */
  4731         mstate fm = (mstate) msp;
  4732 #endif /* FOOTERS */
  4733         if (!ok_magic (fm)) {
  4734             USAGE_ERROR_ACTION (fm, p);
  4735             return;
  4736         }
  4737         if (!PREACTION (fm)) {
  4738             check_inuse_chunk (fm, p);
  4739             if (RTCHECK (ok_address (fm, p) && ok_cinuse (p))) {
  4740                 size_t psize = chunksize (p);
  4741                 mchunkptr next = chunk_plus_offset (p, psize);
  4742                 if (!pinuse (p)) {
  4743                     size_t prevsize = p->prev_foot;
  4744                     if ((prevsize & IS_MMAPPED_BIT) != 0) {
  4745                         prevsize &= ~IS_MMAPPED_BIT;
  4746                         psize += prevsize + MMAP_FOOT_PAD;
  4747                         if (CALL_MUNMAP ((char *) p - prevsize, psize) == 0)
  4748                             fm->footprint -= psize;
  4749                         goto postaction;
  4750                     } else {
  4751                         mchunkptr prev = chunk_minus_offset (p, prevsize);
  4752                         psize += prevsize;
  4753                         p = prev;
  4754                         if (RTCHECK (ok_address (fm, prev))) {  /* consolidate backward */
  4755                             if (p != fm->dv) {
  4756                                 unlink_chunk (fm, p, prevsize);
  4757                             } else if ((next->head & INUSE_BITS) ==
  4758                                        INUSE_BITS) {
  4759                                 fm->dvsize = psize;
  4760                                 set_free_with_pinuse (p, psize, next);
  4761                                 goto postaction;
  4762                             }
  4763                         } else
  4764                             goto erroraction;
  4765                     }
  4766                 }
  4767 
  4768                 if (RTCHECK (ok_next (p, next) && ok_pinuse (next))) {
  4769                     if (!cinuse (next)) {       /* consolidate forward */
  4770                         if (next == fm->top) {
  4771                             size_t tsize = fm->topsize += psize;
  4772                             fm->top = p;
  4773                             p->head = tsize | PINUSE_BIT;
  4774                             if (p == fm->dv) {
  4775                                 fm->dv = 0;
  4776                                 fm->dvsize = 0;
  4777                             }
  4778                             if (should_trim (fm, tsize))
  4779                                 sys_trim (fm, 0);
  4780                             goto postaction;
  4781                         } else if (next == fm->dv) {
  4782                             size_t dsize = fm->dvsize += psize;
  4783                             fm->dv = p;
  4784                             set_size_and_pinuse_of_free_chunk (p, dsize);
  4785                             goto postaction;
  4786                         } else {
  4787                             size_t nsize = chunksize (next);
  4788                             psize += nsize;
  4789                             unlink_chunk (fm, next, nsize);
  4790                             set_size_and_pinuse_of_free_chunk (p, psize);
  4791                             if (p == fm->dv) {
  4792                                 fm->dvsize = psize;
  4793                                 goto postaction;
  4794                             }
  4795                         }
  4796                     } else
  4797                         set_free_with_pinuse (p, psize, next);
  4798                     insert_chunk (fm, p, psize);
  4799                     check_free_chunk (fm, p);
  4800                     goto postaction;
  4801                 }
  4802             }
  4803           erroraction:
  4804             USAGE_ERROR_ACTION (fm, p);
  4805           postaction:
  4806             POSTACTION (fm);
  4807         }
  4808     }
  4809 }
  4810 
  4811 void *
  4812 mspace_calloc (mspace msp, size_t n_elements, size_t elem_size)
  4813 {
  4814     void *mem;
  4815     size_t req = 0;
  4816     mstate ms = (mstate) msp;
  4817     if (!ok_magic (ms)) {
  4818         USAGE_ERROR_ACTION (ms, ms);
  4819         return 0;
  4820     }
  4821     if (n_elements != 0) {
  4822         req = n_elements * elem_size;
  4823         if (((n_elements | elem_size) & ~(size_t) 0xffff) &&
  4824             (req / n_elements != elem_size))
  4825             req = MAX_SIZE_T;   /* force downstream failure on overflow */
  4826     }
  4827     mem = internal_malloc (ms, req);
  4828     if (mem != 0 && calloc_must_clear (mem2chunk (mem)))
  4829         memset (mem, 0, req);
  4830     return mem;
  4831 }
  4832 
  4833 void *
  4834 mspace_realloc (mspace msp, void *oldmem, size_t bytes)
  4835 {
  4836     if (oldmem == 0)
  4837         return mspace_malloc (msp, bytes);
  4838 #ifdef REALLOC_ZERO_BYTES_FREES
  4839     if (bytes == 0) {
  4840         mspace_free (msp, oldmem);
  4841         return 0;
  4842     }
  4843 #endif /* REALLOC_ZERO_BYTES_FREES */
  4844     else {
  4845 #if FOOTERS
  4846         mchunkptr p = mem2chunk (oldmem);
  4847         mstate ms = get_mstate_for (p);
  4848 #else /* FOOTERS */
  4849         mstate ms = (mstate) msp;
  4850 #endif /* FOOTERS */
  4851         if (!ok_magic (ms)) {
  4852             USAGE_ERROR_ACTION (ms, ms);
  4853             return 0;
  4854         }
  4855         return internal_realloc (ms, oldmem, bytes);
  4856     }
  4857 }
  4858 
  4859 void *
  4860 mspace_memalign (mspace msp, size_t alignment, size_t bytes)
  4861 {
  4862     mstate ms = (mstate) msp;
  4863     if (!ok_magic (ms)) {
  4864         USAGE_ERROR_ACTION (ms, ms);
  4865         return 0;
  4866     }
  4867     return internal_memalign (ms, alignment, bytes);
  4868 }
  4869 
  4870 void **
  4871 mspace_independent_calloc (mspace msp, size_t n_elements,
  4872                            size_t elem_size, void *chunks[])
  4873 {
  4874     size_t sz = elem_size;      /* serves as 1-element array */
  4875     mstate ms = (mstate) msp;
  4876     if (!ok_magic (ms)) {
  4877         USAGE_ERROR_ACTION (ms, ms);
  4878         return 0;
  4879     }
  4880     return ialloc (ms, n_elements, &sz, 3, chunks);
  4881 }
  4882 
  4883 void **
  4884 mspace_independent_comalloc (mspace msp, size_t n_elements,
  4885                              size_t sizes[], void *chunks[])
  4886 {
  4887     mstate ms = (mstate) msp;
  4888     if (!ok_magic (ms)) {
  4889         USAGE_ERROR_ACTION (ms, ms);
  4890         return 0;
  4891     }
  4892     return ialloc (ms, n_elements, sizes, 0, chunks);
  4893 }
  4894 
  4895 int
  4896 mspace_trim (mspace msp, size_t pad)
  4897 {
  4898     int result = 0;
  4899     mstate ms = (mstate) msp;
  4900     if (ok_magic (ms)) {
  4901         if (!PREACTION (ms)) {
  4902             result = sys_trim (ms, pad);
  4903             POSTACTION (ms);
  4904         }
  4905     } else {
  4906         USAGE_ERROR_ACTION (ms, ms);
  4907     }
  4908     return result;
  4909 }
  4910 
  4911 void
  4912 mspace_malloc_stats (mspace msp)
  4913 {
  4914     mstate ms = (mstate) msp;
  4915     if (ok_magic (ms)) {
  4916         internal_malloc_stats (ms);
  4917     } else {
  4918         USAGE_ERROR_ACTION (ms, ms);
  4919     }
  4920 }
  4921 
  4922 size_t
  4923 mspace_footprint (mspace msp)
  4924 {
  4925     size_t result;
  4926     mstate ms = (mstate) msp;
  4927     if (ok_magic (ms)) {
  4928         result = ms->footprint;
  4929     }
  4930     USAGE_ERROR_ACTION (ms, ms);
  4931     return result;
  4932 }
  4933 
  4934 
  4935 size_t
  4936 mspace_max_footprint (mspace msp)
  4937 {
  4938     size_t result;
  4939     mstate ms = (mstate) msp;
  4940     if (ok_magic (ms)) {
  4941         result = ms->max_footprint;
  4942     }
  4943     USAGE_ERROR_ACTION (ms, ms);
  4944     return result;
  4945 }
  4946 
  4947 
  4948 #if !NO_MALLINFO
  4949 struct mallinfo
  4950 mspace_mallinfo (mspace msp)
  4951 {
  4952     mstate ms = (mstate) msp;
  4953     if (!ok_magic (ms)) {
  4954         USAGE_ERROR_ACTION (ms, ms);
  4955     }
  4956     return internal_mallinfo (ms);
  4957 }
  4958 #endif /* NO_MALLINFO */
  4959 
  4960 int
  4961 mspace_mallopt (int param_number, int value)
  4962 {
  4963     return change_mparam (param_number, value);
  4964 }
  4965 
  4966 #endif /* MSPACES */
  4967 
  4968 /* -------------------- Alternative MORECORE functions ------------------- */
  4969 
  4970 /*
  4971   Guidelines for creating a custom version of MORECORE:
  4972 
  4973   * For best performance, MORECORE should allocate in multiples of pagesize.
  4974   * MORECORE may allocate more memory than requested. (Or even less,
  4975       but this will usually result in a malloc failure.)
  4976   * MORECORE must not allocate memory when given argument zero, but
  4977       instead return one past the end address of memory from previous
  4978       nonzero call.
  4979   * For best performance, consecutive calls to MORECORE with positive
  4980       arguments should return increasing addresses, indicating that
  4981       space has been contiguously extended.
  4982   * Even though consecutive calls to MORECORE need not return contiguous
  4983       addresses, it must be OK for malloc'ed chunks to span multiple
  4984       regions in those cases where they do happen to be contiguous.
  4985   * MORECORE need not handle negative arguments -- it may instead
  4986       just return MFAIL when given negative arguments.
  4987       Negative arguments are always multiples of pagesize. MORECORE
  4988       must not misinterpret negative args as large positive unsigned
  4989       args. You can suppress all such calls from even occurring by defining
  4990       MORECORE_CANNOT_TRIM,
  4991 
  4992   As an example alternative MORECORE, here is a custom allocator
  4993   kindly contributed for pre-OSX macOS.  It uses virtually but not
  4994   necessarily physically contiguous non-paged memory (locked in,
  4995   present and won't get swapped out).  You can use it by uncommenting
  4996   this section, adding some #includes, and setting up the appropriate
  4997   defines above:
  4998 
  4999       #define MORECORE osMoreCore
  5000 
  5001   There is also a shutdown routine that should somehow be called for
  5002   cleanup upon program exit.
  5003 
  5004   #define MAX_POOL_ENTRIES 100
  5005   #define MINIMUM_MORECORE_SIZE  (64 * 1024U)
  5006   static int next_os_pool;
  5007   void *our_os_pools[MAX_POOL_ENTRIES];
  5008 
  5009   void *osMoreCore(int size)
  5010   {
  5011     void *ptr = 0;
  5012     static void *sbrk_top = 0;
  5013 
  5014     if (size > 0)
  5015     {
  5016       if (size < MINIMUM_MORECORE_SIZE)
  5017          size = MINIMUM_MORECORE_SIZE;
  5018       if (CurrentExecutionLevel() == kTaskLevel)
  5019          ptr = PoolAllocateResident(size + RM_PAGE_SIZE, 0);
  5020       if (ptr == 0)
  5021       {
  5022         return (void *) MFAIL;
  5023       }
  5024       // save ptrs so they can be freed during cleanup
  5025       our_os_pools[next_os_pool] = ptr;
  5026       next_os_pool++;
  5027       ptr = (void *) ((((size_t) ptr) + RM_PAGE_MASK) & ~RM_PAGE_MASK);
  5028       sbrk_top = (char *) ptr + size;
  5029       return ptr;
  5030     }
  5031     else if (size < 0)
  5032     {
  5033       // we don't currently support shrink behavior
  5034       return (void *) MFAIL;
  5035     }
  5036     else
  5037     {
  5038       return sbrk_top;
  5039     }
  5040   }
  5041 
  5042   // cleanup any allocated memory pools
  5043   // called as last thing before shutting down driver
  5044 
  5045   void osCleanupMem(void)
  5046   {
  5047     void **ptr;
  5048 
  5049     for (ptr = our_os_pools; ptr < &our_os_pools[MAX_POOL_ENTRIES]; ptr++)
  5050       if (*ptr)
  5051       {
  5052          PoolDeallocate(*ptr);
  5053          *ptr = 0;
  5054       }
  5055   }
  5056 
  5057 */
  5058 
  5059 
  5060 /* -----------------------------------------------------------------------
  5061 History:
  5062     V2.8.3 Thu Sep 22 11:16:32 2005  Doug Lea  (dl at gee)
  5063       * Add max_footprint functions
  5064       * Ensure all appropriate literals are size_t
  5065       * Fix conditional compilation problem for some #define settings
  5066       * Avoid concatenating segments with the one provided
  5067         in create_mspace_with_base
  5068       * Rename some variables to avoid compiler shadowing warnings
  5069       * Use explicit lock initialization.
  5070       * Better handling of sbrk interference.
  5071       * Simplify and fix segment insertion, trimming and mspace_destroy
  5072       * Reinstate REALLOC_ZERO_BYTES_FREES option from 2.7.x
  5073       * Thanks especially to Dennis Flanagan for help on these.
  5074 
  5075     V2.8.2 Sun Jun 12 16:01:10 2005  Doug Lea  (dl at gee)
  5076       * Fix memalign brace error.
  5077 
  5078     V2.8.1 Wed Jun  8 16:11:46 2005  Doug Lea  (dl at gee)
  5079       * Fix improper #endif nesting in C++
  5080       * Add explicit casts needed for C++
  5081 
  5082     V2.8.0 Mon May 30 14:09:02 2005  Doug Lea  (dl at gee)
  5083       * Use trees for large bins
  5084       * Support mspaces
  5085       * Use segments to unify sbrk-based and mmap-based system allocation,
  5086         removing need for emulation on most platforms without sbrk.
  5087       * Default safety checks
  5088       * Optional footer checks. Thanks to William Robertson for the idea.
  5089       * Internal code refactoring
  5090       * Incorporate suggestions and platform-specific changes.
  5091         Thanks to Dennis Flanagan, Colin Plumb, Niall Douglas,
  5092         Aaron Bachmann,  Emery Berger, and others.
  5093       * Speed up non-fastbin processing enough to remove fastbins.
  5094       * Remove useless cfree() to avoid conflicts with other apps.
  5095       * Remove internal memcpy, memset. Compilers handle builtins better.
  5096       * Remove some options that no one ever used and rename others.
  5097 
  5098     V2.7.2 Sat Aug 17 09:07:30 2002  Doug Lea  (dl at gee)
  5099       * Fix malloc_state bitmap array misdeclaration
  5100 
  5101     V2.7.1 Thu Jul 25 10:58:03 2002  Doug Lea  (dl at gee)
  5102       * Allow tuning of FIRST_SORTED_BIN_SIZE
  5103       * Use PTR_UINT as type for all ptr->int casts. Thanks to John Belmonte.
  5104       * Better detection and support for non-contiguousness of MORECORE.
  5105         Thanks to Andreas Mueller, Conal Walsh, and Wolfram Gloger
  5106       * Bypass most of malloc if no frees. Thanks To Emery Berger.
  5107       * Fix freeing of old top non-contiguous chunk im sysmalloc.
  5108       * Raised default trim and map thresholds to 256K.
  5109       * Fix mmap-related #defines. Thanks to Lubos Lunak.
  5110       * Fix copy macros; added LACKS_FCNTL_H. Thanks to Neal Walfield.
  5111       * Branch-free bin calculation
  5112       * Default trim and mmap thresholds now 256K.
  5113 
  5114     V2.7.0 Sun Mar 11 14:14:06 2001  Doug Lea  (dl at gee)
  5115       * Introduce independent_comalloc and independent_calloc.
  5116         Thanks to Michael Pachos for motivation and help.
  5117       * Make optional .h file available
  5118       * Allow > 2GB requests on 32bit systems.
  5119       * new WIN32 sbrk, mmap, munmap, lock code from <Walter@GeNeSys-e.de>.
  5120         Thanks also to Andreas Mueller <a.mueller at paradatec.de>,
  5121         and Anonymous.
  5122       * Allow override of MALLOC_ALIGNMENT (Thanks to Ruud Waij for
  5123         helping test this.)
  5124       * memalign: check alignment arg
  5125       * realloc: don't try to shift chunks backwards, since this
  5126         leads to  more fragmentation in some programs and doesn't
  5127         seem to help in any others.
  5128       * Collect all cases in malloc requiring system memory into sysmalloc
  5129       * Use mmap as backup to sbrk
  5130       * Place all internal state in malloc_state
  5131       * Introduce fastbins (although similar to 2.5.1)
  5132       * Many minor tunings and cosmetic improvements
  5133       * Introduce USE_PUBLIC_MALLOC_WRAPPERS, USE_MALLOC_LOCK
  5134       * Introduce MALLOC_FAILURE_ACTION, MORECORE_CONTIGUOUS
  5135         Thanks to Tony E. Bennett <tbennett@nvidia.com> and others.
  5136       * Include errno.h to support default failure action.
  5137 
  5138     V2.6.6 Sun Dec  5 07:42:19 1999  Doug Lea  (dl at gee)
  5139       * return null for negative arguments
  5140       * Added Several WIN32 cleanups from Martin C. Fong <mcfong at yahoo.com>
  5141          * Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h'
  5142           (e.g. WIN32 platforms)
  5143          * Cleanup header file inclusion for WIN32 platforms
  5144          * Cleanup code to avoid Microsoft Visual C++ compiler complaints
  5145          * Add 'USE_DL_PREFIX' to quickly allow co-existence with existing
  5146            memory allocation routines
  5147          * Set 'malloc_getpagesize' for WIN32 platforms (needs more work)
  5148          * Use 'assert' rather than 'ASSERT' in WIN32 code to conform to
  5149            usage of 'assert' in non-WIN32 code
  5150          * Improve WIN32 'sbrk()' emulation's 'findRegion()' routine to
  5151            avoid infinite loop
  5152       * Always call 'fREe()' rather than 'free()'
  5153 
  5154     V2.6.5 Wed Jun 17 15:57:31 1998  Doug Lea  (dl at gee)
  5155       * Fixed ordering problem with boundary-stamping
  5156 
  5157     V2.6.3 Sun May 19 08:17:58 1996  Doug Lea  (dl at gee)
  5158       * Added pvalloc, as recommended by H.J. Liu
  5159       * Added 64bit pointer support mainly from Wolfram Gloger
  5160       * Added anonymously donated WIN32 sbrk emulation
  5161       * Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen
  5162       * malloc_extend_top: fix mask error that caused wastage after
  5163         foreign sbrks
  5164       * Add linux mremap support code from HJ Liu
  5165 
  5166     V2.6.2 Tue Dec  5 06:52:55 1995  Doug Lea  (dl at gee)
  5167       * Integrated most documentation with the code.
  5168       * Add support for mmap, with help from
  5169         Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
  5170       * Use last_remainder in more cases.
  5171       * Pack bins using idea from  colin@nyx10.cs.du.edu
  5172       * Use ordered bins instead of best-fit threshhold
  5173       * Eliminate block-local decls to simplify tracing and debugging.
  5174       * Support another case of realloc via move into top
  5175       * Fix error occuring when initial sbrk_base not word-aligned.
  5176       * Rely on page size for units instead of SBRK_UNIT to
  5177         avoid surprises about sbrk alignment conventions.
  5178       * Add mallinfo, mallopt. Thanks to Raymond Nijssen
  5179         (raymond@es.ele.tue.nl) for the suggestion.
  5180       * Add `pad' argument to malloc_trim and top_pad mallopt parameter.
  5181       * More precautions for cases where other routines call sbrk,
  5182         courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
  5183       * Added macros etc., allowing use in linux libc from
  5184         H.J. Lu (hjl@gnu.ai.mit.edu)
  5185       * Inverted this history list
  5186 
  5187     V2.6.1 Sat Dec  2 14:10:57 1995  Doug Lea  (dl at gee)
  5188       * Re-tuned and fixed to behave more nicely with V2.6.0 changes.
  5189       * Removed all preallocation code since under current scheme
  5190         the work required to undo bad preallocations exceeds
  5191         the work saved in good cases for most test programs.
  5192       * No longer use return list or unconsolidated bins since
  5193         no scheme using them consistently outperforms those that don't
  5194         given above changes.
  5195       * Use best fit for very large chunks to prevent some worst-cases.
  5196       * Added some support for debugging
  5197 
  5198     V2.6.0 Sat Nov  4 07:05:23 1995  Doug Lea  (dl at gee)
  5199       * Removed footers when chunks are in use. Thanks to
  5200         Paul Wilson (wilson@cs.texas.edu) for the suggestion.
  5201 
  5202     V2.5.4 Wed Nov  1 07:54:51 1995  Doug Lea  (dl at gee)
  5203       * Added malloc_trim, with help from Wolfram Gloger
  5204         (wmglo@Dent.MED.Uni-Muenchen.DE).
  5205 
  5206     V2.5.3 Tue Apr 26 10:16:01 1994  Doug Lea  (dl at g)
  5207 
  5208     V2.5.2 Tue Apr  5 16:20:40 1994  Doug Lea  (dl at g)
  5209       * realloc: try to expand in both directions
  5210       * malloc: swap order of clean-bin strategy;
  5211       * realloc: only conditionally expand backwards
  5212       * Try not to scavenge used bins
  5213       * Use bin counts as a guide to preallocation
  5214       * Occasionally bin return list chunks in first scan
  5215       * Add a few optimizations from colin@nyx10.cs.du.edu
  5216 
  5217     V2.5.1 Sat Aug 14 15:40:43 1993  Doug Lea  (dl at g)
  5218       * faster bin computation & slightly different binning
  5219       * merged all consolidations to one part of malloc proper
  5220          (eliminating old malloc_find_space & malloc_clean_bin)
  5221       * Scan 2 returns chunks (not just 1)
  5222       * Propagate failure in realloc if malloc returns 0
  5223       * Add stuff to allow compilation on non-ANSI compilers
  5224           from kpv@research.att.com
  5225 
  5226     V2.5 Sat Aug  7 07:41:59 1993  Doug Lea  (dl at g.oswego.edu)
  5227       * removed potential for odd address access in prev_chunk
  5228       * removed dependency on getpagesize.h
  5229       * misc cosmetics and a bit more internal documentation
  5230       * anticosmetics: mangled names in macros to evade debugger strangeness
  5231       * tested on sparc, hp-700, dec-mips, rs6000
  5232           with gcc & native cc (hp, dec only) allowing
  5233           Detlefs & Zorn comparison study (in SIGPLAN Notices.)
  5234 
  5235     Trial version Fri Aug 28 13:14:29 1992  Doug Lea  (dl at g.oswego.edu)
  5236       * Based loosely on libg++-1.2X malloc. (It retains some of the overall
  5237          structure of old version,  but most details differ.)
  5238  
  5239 */
  5240 
  5241 #endif /* !HAVE_MALLOC */
  5242 /* vi: set ts=4 sw=4 expandtab: */