src/SDL_hints.c
author Sam Lantinga <slouken@libsdl.org>
Thu, 16 May 2013 00:43:22 -0700
changeset 7180 3733e68edbc3
parent 6885 700f1b25f77f
child 7191 75360622e65f
permissions -rw-r--r--
Fixed bug 1846 - _allmul implementation in SDL_stdlib.c doesn't clean up the stack

Colin Barrett

I see this manifest itself (VS2012 x86) as:

"Run-Time Check Failure #0 - The value of ESP was not properly saved across a function call. This is usually a result of calling a function declared with one calling convention with a function pointer declared with a different calling convention."

in the first call to SDL_GetTicks in my application. The disassembly at the problem line is:

hires_now.QuadPart *= 1000;
00AD0792 push 0
00AD0794 push 3E8h
00AD0799 mov eax,dword ptr [ebp-10h]
00AD079C push eax
00AD079D mov ecx,dword ptr [hires_now]
00AD07A0 push ecx
00AD07A1 call _allmul (0AE7D40h)
00AD07A6 mov dword ptr [hires_now],eax
00AD07A9 mov dword ptr [ebp-10h],edx

Apparently _allmul should be popping the stack but isn't (other similar functions in SDL_stdlib.c - _alldiv and whatnot - DO pop the stack).

A 'ret 10h' at the end of _allmul appears to do the trick
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2013 Sam Lantinga <slouken@libsdl.org>
     4 
     5   This software is provided 'as-is', without any express or implied
     6   warranty.  In no event will the authors be held liable for any damages
     7   arising from the use of this software.
     8 
     9   Permission is granted to anyone to use this software for any purpose,
    10   including commercial applications, and to alter it and redistribute it
    11   freely, subject to the following restrictions:
    12 
    13   1. The origin of this software must not be misrepresented; you must not
    14      claim that you wrote the original software. If you use this software
    15      in a product, an acknowledgment in the product documentation would be
    16      appreciated but is not required.
    17   2. Altered source versions must be plainly marked as such, and must not be
    18      misrepresented as being the original software.
    19   3. This notice may not be removed or altered from any source distribution.
    20 */
    21 #include "SDL_config.h"
    22 
    23 #include "SDL_hints.h"
    24 #include "SDL_hints_c.h"
    25 
    26 
    27 /* Assuming there aren't many hints set and they aren't being queried in
    28    critical performance paths, we'll just use a linked list here.
    29  */
    30 typedef struct SDL_Hint {
    31     char *name;
    32     char *value;
    33     SDL_HintPriority priority;
    34     SDL_HintChangedCb callback;
    35     struct SDL_Hint *next;
    36 } SDL_Hint;
    37 
    38 static SDL_Hint *SDL_hints;
    39 
    40 SDL_bool
    41 SDL_RegisterHintChangedCb(const char *name, SDL_HintChangedCb hintCb)
    42 {
    43     SDL_Hint *hint;
    44 	
    45     for (hint = SDL_hints; hint; hint = hint->next) {
    46         if (SDL_strcmp(name, hint->name) == 0) {
    47             hint->callback = hintCb;
    48             return SDL_TRUE;
    49         }
    50     }
    51 	
    52     return SDL_FALSE;
    53 }
    54 
    55 SDL_bool
    56 SDL_SetHintWithPriority(const char *name, const char *value,
    57                         SDL_HintPriority priority)
    58 {
    59     const char *env;
    60     SDL_Hint *hint;
    61 
    62     if (!name || !value) {
    63         return SDL_FALSE;
    64     }
    65 
    66     env = SDL_getenv(name);
    67     if (env && priority < SDL_HINT_OVERRIDE) {
    68         return SDL_FALSE;
    69     }
    70 
    71     for (hint = SDL_hints; hint; hint = hint->next) {
    72         if (SDL_strcmp(name, hint->name) == 0) {
    73             if (priority < hint->priority) {
    74                 return SDL_FALSE;
    75             }
    76             if (SDL_strcmp(hint->value, value) != 0) {
    77                 if (hint->callback != NULL) {
    78                     (*hint->callback)(name, hint->value, value);
    79                 }
    80                 SDL_free(hint->value);
    81                 hint->value = SDL_strdup(value);
    82             }
    83             hint->priority = priority;
    84             return SDL_TRUE;
    85         }
    86     }
    87 
    88     /* Couldn't find the hint, add a new one */
    89     hint = (SDL_Hint *)SDL_malloc(sizeof(*hint));
    90     if (!hint) {
    91         return SDL_FALSE;
    92     }
    93     hint->name = SDL_strdup(name);
    94     hint->value = SDL_strdup(value);
    95     hint->priority = priority;
    96     hint->callback = NULL;
    97     hint->next = SDL_hints;
    98     SDL_hints = hint;
    99     return SDL_TRUE;
   100 }
   101 
   102 SDL_bool
   103 SDL_SetHint(const char *name, const char *value)
   104 {
   105     return SDL_SetHintWithPriority(name, value, SDL_HINT_NORMAL);
   106 }
   107 
   108 const char *
   109 SDL_GetHint(const char *name)
   110 {
   111     const char *env;
   112     SDL_Hint *hint;
   113 
   114     env = SDL_getenv(name);
   115     for (hint = SDL_hints; hint; hint = hint->next) {
   116         if (SDL_strcmp(name, hint->name) == 0) {
   117             if (!env || hint->priority == SDL_HINT_OVERRIDE) {
   118                 return hint->value;
   119             }
   120             break;
   121         }
   122     }
   123     return env;
   124 }
   125 
   126 void SDL_ClearHints(void)
   127 {
   128     SDL_Hint *hint;
   129 
   130     while (SDL_hints) {
   131         hint = SDL_hints;
   132         SDL_hints = hint->next;
   133 
   134         SDL_free(hint->name);
   135         SDL_free(hint->value);
   136         SDL_free(hint);
   137     }
   138 }
   139 
   140 /* vi: set ts=4 sw=4 expandtab: */