src/file/SDL_rwops.c
author Sam Lantinga <slouken@libsdl.org>
Tue, 07 Feb 2006 06:59:48 +0000
changeset 1336 3692456e7b0f
parent 1330 450721ad5436
child 1338 604d73db6802
permissions -rw-r--r--
Use SDL_ prefixed versions of C library functions.
FIXME:
Change #include <stdlib.h> to #include "SDL_stdlib.h"
Change #include <string.h> to #include "SDL_string.h"
Make sure nothing else broke because of this...
     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 
    23 /* This file provides a general interface for SDL to read and write
    24    data sources.  It can easily be extended to files, memory, etc.
    25 */
    26 
    27 #include "SDL_error.h"
    28 #include "SDL_rwops.h"
    29 #include "SDL_stdlib.h"
    30 #include "SDL_string.h"
    31 
    32 #ifdef HAVE_STDIO_H
    33 
    34 /* Functions to read/write stdio file pointers */
    35 
    36 static int stdio_seek(SDL_RWops *context, int offset, int whence)
    37 {
    38 	if ( fseek(context->hidden.stdio.fp, offset, whence) == 0 ) {
    39 		return(ftell(context->hidden.stdio.fp));
    40 	} else {
    41 		SDL_Error(SDL_EFSEEK);
    42 		return(-1);
    43 	}
    44 }
    45 static int stdio_read(SDL_RWops *context, void *ptr, int size, int maxnum)
    46 {
    47 	size_t nread;
    48 
    49 	nread = fread(ptr, size, maxnum, context->hidden.stdio.fp); 
    50 	if ( nread == 0 && ferror(context->hidden.stdio.fp) ) {
    51 		SDL_Error(SDL_EFREAD);
    52 	}
    53 	return(nread);
    54 }
    55 static int stdio_write(SDL_RWops *context, const void *ptr, int size, int num)
    56 {
    57 	size_t nwrote;
    58 
    59 	nwrote = fwrite(ptr, size, num, context->hidden.stdio.fp);
    60 	if ( nwrote == 0 && ferror(context->hidden.stdio.fp) ) {
    61 		SDL_Error(SDL_EFWRITE);
    62 	}
    63 	return(nwrote);
    64 }
    65 static int stdio_close(SDL_RWops *context)
    66 {
    67 	if ( context ) {
    68 		if ( context->hidden.stdio.autoclose ) {
    69 			/* WARNING:  Check the return value here! */
    70 			fclose(context->hidden.stdio.fp);
    71 		}
    72 		SDL_FreeRW(context);
    73 	}
    74 	return(0);
    75 }
    76 
    77 #endif /* HAVE_STDIO_H */
    78 
    79 /* Functions to read/write memory pointers */
    80 
    81 static int mem_seek(SDL_RWops *context, int offset, int whence)
    82 {
    83 	Uint8 *newpos;
    84 
    85 	switch (whence) {
    86 		case RW_SEEK_SET:
    87 			newpos = context->hidden.mem.base+offset;
    88 			break;
    89 		case RW_SEEK_CUR:
    90 			newpos = context->hidden.mem.here+offset;
    91 			break;
    92 		case RW_SEEK_END:
    93 			newpos = context->hidden.mem.stop+offset;
    94 			break;
    95 		default:
    96 			SDL_SetError("Unknown value for 'whence'");
    97 			return(-1);
    98 	}
    99 	if ( newpos < context->hidden.mem.base ) {
   100 		newpos = context->hidden.mem.base;
   101 	}
   102 	if ( newpos > context->hidden.mem.stop ) {
   103 		newpos = context->hidden.mem.stop;
   104 	}
   105 	context->hidden.mem.here = newpos;
   106 	return(context->hidden.mem.here-context->hidden.mem.base);
   107 }
   108 static int mem_read(SDL_RWops *context, void *ptr, int size, int maxnum)
   109 {
   110 	int total_bytes;
   111 	int mem_available;
   112 
   113 	total_bytes = (maxnum * size);
   114 	if ( (maxnum <= 0) || (size <= 0) || ((total_bytes / maxnum) != size) ) {
   115 		return 0;
   116 	}
   117 
   118 	mem_available = (context->hidden.mem.stop - context->hidden.mem.here);
   119 	if (total_bytes > mem_available) {
   120 		total_bytes = mem_available;
   121 	}
   122 
   123 	SDL_memcpy(ptr, context->hidden.mem.here, total_bytes);
   124 	context->hidden.mem.here += total_bytes;
   125 
   126 	return (total_bytes / size);
   127 }
   128 static int mem_write(SDL_RWops *context, const void *ptr, int size, int num)
   129 {
   130 	if ( (context->hidden.mem.here + (num*size)) > context->hidden.mem.stop ) {
   131 		num = (context->hidden.mem.stop-context->hidden.mem.here)/size;
   132 	}
   133 	SDL_memcpy(context->hidden.mem.here, ptr, num*size);
   134 	context->hidden.mem.here += num*size;
   135 	return(num);
   136 }
   137 static int mem_writeconst(SDL_RWops *context, const void *ptr, int size, int num)
   138 {
   139 	SDL_SetError("Can't write to read-only memory");
   140 	return(-1);
   141 }
   142 static int mem_close(SDL_RWops *context)
   143 {
   144 	if ( context ) {
   145 		SDL_FreeRW(context);
   146 	}
   147 	return(0);
   148 }
   149 
   150 /* Functions to create SDL_RWops structures from various data sources */
   151 #ifdef WIN32
   152 /* Aggh.  You can't (apparently) open a file in an application and
   153    read from it in a DLL.
   154 */
   155 static int in_sdl = 0;
   156 #endif
   157 
   158 #ifdef macintosh
   159 /*
   160  * translate unix-style slash-separated filename to mac-style colon-separated
   161  * name; return malloced string
   162  */
   163 static char *unix_to_mac(const char *file)
   164 {
   165 	int flen = SDL_strlen(file);
   166 	char *path = SDL_malloc(flen + 2);
   167 	const char *src = file;
   168 	char *dst = path;
   169 	if(*src == '/') {
   170 		/* really depends on filesystem layout, hope for the best */
   171 		src++;
   172 	} else {
   173 		/* Check if this is a MacOS path to begin with */
   174 		if(*src != ':')
   175 			*dst++ = ':';   /* relative paths begin with ':' */
   176 	}
   177 	while(src < file + flen) {
   178 		const char *end = SDL_strchr(src, '/');
   179 		int len;
   180 		if(!end)
   181 			end = file + flen; /* last component */
   182 		len = end - src;
   183 		if(len == 0 || (len == 1 && src[0] == '.')) {
   184 			/* remove repeated slashes and . */
   185 		} else {
   186 			if(len == 2 && src[0] == '.' && src[1] == '.') {
   187 				/* replace .. with the empty string */
   188 			} else {
   189 				SDL_memcpy(dst, src, len);
   190 				dst += len;
   191 			}
   192 			if(end < file + flen)
   193 				*dst++ = ':';
   194 		}
   195 		src = end + 1;
   196 	}
   197 	*dst++ = '\0';
   198 	return path;
   199 }
   200 #endif /* macintosh */
   201 
   202 SDL_RWops *SDL_RWFromFile(const char *file, const char *mode)
   203 {
   204 	SDL_RWops *rwops = NULL;
   205 #ifdef HAVE_STDIO_H
   206 	FILE *fp;
   207 
   208 #ifdef macintosh
   209 	{
   210 		char *mpath = unix_to_mac(file);
   211 		fp = fopen(mpath, mode);
   212 		SDL_free(mpath);
   213 	}
   214 #else
   215 	fp = fopen(file, mode);
   216 #endif
   217 	if ( fp == NULL ) {
   218 		SDL_SetError("Couldn't open %s", file);
   219 	} else {
   220 #ifdef WIN32
   221 		in_sdl = 1;
   222 		rwops = SDL_RWFromFP(fp, 1);
   223 		in_sdl = 0;
   224 #else
   225 		rwops = SDL_RWFromFP(fp, 1);
   226 #endif
   227 	}
   228 #endif /* HAVE_STDIO_H */
   229 	return(rwops);
   230 }
   231 
   232 #ifdef HAVE_STDIO_H
   233 SDL_RWops *SDL_RWFromFP(FILE *fp, int autoclose)
   234 {
   235 	SDL_RWops *rwops = NULL;
   236 
   237 #ifdef WIN32
   238 	if ( ! in_sdl ) {
   239 		/* It's when SDL and the app are compiled with different C runtimes */
   240 		SDL_SetError("You can't pass a FILE pointer to a DLL (?)");
   241 		/*return(NULL);*/
   242 	}
   243 #endif
   244 	rwops = SDL_AllocRW();
   245 	if ( rwops != NULL ) {
   246 		rwops->seek = stdio_seek;
   247 		rwops->read = stdio_read;
   248 		rwops->write = stdio_write;
   249 		rwops->close = stdio_close;
   250 		rwops->hidden.stdio.fp = fp;
   251 		rwops->hidden.stdio.autoclose = autoclose;
   252 	}
   253 	return(rwops);
   254 }
   255 #endif /* HAVE_STDIO_H */
   256 
   257 SDL_RWops *SDL_RWFromMem(void *mem, int size)
   258 {
   259 	SDL_RWops *rwops;
   260 
   261 	rwops = SDL_AllocRW();
   262 	if ( rwops != NULL ) {
   263 		rwops->seek = mem_seek;
   264 		rwops->read = mem_read;
   265 		rwops->write = mem_write;
   266 		rwops->close = mem_close;
   267 		rwops->hidden.mem.base = (Uint8 *)mem;
   268 		rwops->hidden.mem.here = rwops->hidden.mem.base;
   269 		rwops->hidden.mem.stop = rwops->hidden.mem.base+size;
   270 	}
   271 	return(rwops);
   272 }
   273 
   274 SDL_RWops *SDL_RWFromConstMem(const void *mem, int size)
   275 {
   276 	SDL_RWops *rwops;
   277 
   278 	rwops = SDL_AllocRW();
   279 	if ( rwops != NULL ) {
   280 		rwops->seek = mem_seek;
   281 		rwops->read = mem_read;
   282 		rwops->write = mem_writeconst;
   283 		rwops->close = mem_close;
   284 		rwops->hidden.mem.base = (Uint8 *)mem;
   285 		rwops->hidden.mem.here = rwops->hidden.mem.base;
   286 		rwops->hidden.mem.stop = rwops->hidden.mem.base+size;
   287 	}
   288 	return(rwops);
   289 }
   290 
   291 SDL_RWops *SDL_AllocRW(void)
   292 {
   293 	SDL_RWops *area;
   294 
   295 	area = (SDL_RWops *)SDL_malloc(sizeof *area);
   296 	if ( area == NULL ) {
   297 		SDL_OutOfMemory();
   298 	}
   299 	return(area);
   300 }
   301 
   302 void SDL_FreeRW(SDL_RWops *area)
   303 {
   304 	SDL_free(area);
   305 }