src/file/SDL_rwops.c
author Sam Lantinga <slouken@lokigames.com>
Thu, 26 Apr 2001 16:45:43 +0000
changeset 0 74212992fb08
child 36 13ee9f4834ea
permissions -rw-r--r--
Initial revision
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997, 1998, 1999, 2000, 2001  Sam Lantinga
     4 
     5     This library is free software; you can redistribute it and/or
     6     modify it under the terms of the GNU Library General Public
     7     License as published by the Free Software Foundation; either
     8     version 2 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     Library General Public License for more details.
    14 
    15     You should have received a copy of the GNU Library General Public
    16     License along with this library; if not, write to the Free
    17     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    18 
    19     Sam Lantinga
    20     slouken@devolution.com
    21 */
    22 
    23 #ifdef SAVE_RCSID
    24 static char rcsid =
    25  "@(#) $Id$";
    26 #endif
    27 
    28 /* This file provides a general interface for SDL to read and write
    29    data sources.  It can easily be extended to files, memory, etc.
    30 */
    31 
    32 #include <stdlib.h>
    33 #include <string.h>
    34 
    35 #include "SDL_error.h"
    36 #include "SDL_rwops.h"
    37 
    38 /* Functions to read/write stdio file pointers */
    39 
    40 static int stdio_seek(SDL_RWops *context, int offset, int whence)
    41 {
    42 	if ( fseek(context->hidden.stdio.fp, offset, whence) == 0 ) {
    43 		return(ftell(context->hidden.stdio.fp));
    44 	} else {
    45 		SDL_Error(SDL_EFSEEK);
    46 		return(-1);
    47 	}
    48 }
    49 static int stdio_read(SDL_RWops *context, void *ptr, int size, int maxnum)
    50 {
    51 	size_t nread;
    52 
    53 	nread = fread(ptr, size, maxnum, context->hidden.stdio.fp); 
    54 	if ( nread == 0 && ferror(context->hidden.stdio.fp) ) {
    55 		SDL_Error(SDL_EFREAD);
    56 	}
    57 	return(nread);
    58 }
    59 static int stdio_write(SDL_RWops *context, const void *ptr, int size, int num)
    60 {
    61 	size_t nwrote;
    62 
    63 	nwrote = fwrite(ptr, size, num, context->hidden.stdio.fp);
    64 	if ( nwrote == 0 && ferror(context->hidden.stdio.fp) ) {
    65 		SDL_Error(SDL_EFWRITE);
    66 	}
    67 	return(nwrote);
    68 }
    69 static int stdio_close(SDL_RWops *context)
    70 {
    71 	if ( context ) {
    72 		if ( context->hidden.stdio.autoclose ) {
    73 			/* WARNING:  Check the return value here! */
    74 			fclose(context->hidden.stdio.fp);
    75 		}
    76 		free(context);
    77 	}
    78 	return(0);
    79 }
    80 
    81 /* Functions to read/write memory pointers */
    82 
    83 static int mem_seek(SDL_RWops *context, int offset, int whence)
    84 {
    85 	Uint8 *newpos;
    86 
    87 	switch (whence) {
    88 		case SEEK_SET:
    89 			newpos = context->hidden.mem.base+offset;
    90 			break;
    91 		case SEEK_CUR:
    92 			newpos = context->hidden.mem.here+offset;
    93 			break;
    94 		case SEEK_END:
    95 			newpos = context->hidden.mem.stop+offset;
    96 			break;
    97 		default:
    98 			SDL_SetError("Unknown value for 'whence'");
    99 			return(-1);
   100 	}
   101 	if ( newpos < context->hidden.mem.base ) {
   102 		newpos = context->hidden.mem.base;
   103 	}
   104 	if ( newpos > context->hidden.mem.stop ) {
   105 		newpos = context->hidden.mem.stop;
   106 	}
   107 	context->hidden.mem.here = newpos;
   108 	return(context->hidden.mem.here-context->hidden.mem.base);
   109 }
   110 static int mem_read(SDL_RWops *context, void *ptr, int size, int maxnum)
   111 {
   112 	int num;
   113 
   114 	num = maxnum;
   115 	if ( (context->hidden.mem.here + (num*size)) > context->hidden.mem.stop ) {
   116 		num = (context->hidden.mem.stop-context->hidden.mem.here)/size;
   117 	}
   118 	memcpy(ptr, context->hidden.mem.here, num*size);
   119 	context->hidden.mem.here += num*size;
   120 	return(num);
   121 }
   122 static int mem_write(SDL_RWops *context, const void *ptr, int size, int num)
   123 {
   124 	if ( (context->hidden.mem.here + (num*size)) > context->hidden.mem.stop ) {
   125 		num = (context->hidden.mem.stop-context->hidden.mem.here)/size;
   126 	}
   127 	memcpy(context->hidden.mem.here, ptr, num*size);
   128 	context->hidden.mem.here += num*size;
   129 	return(num);
   130 }
   131 static int mem_close(SDL_RWops *context)
   132 {
   133 	if ( context ) {
   134 		free(context);
   135 	}
   136 	return(0);
   137 }
   138 
   139 /* Functions to create SDL_RWops structures from various data sources */
   140 #ifdef WIN32
   141 /* Aggh.  You can't (apparently) open a file in an application and
   142    read from it in a DLL.
   143 */
   144 static int in_sdl = 0;
   145 #endif
   146 
   147 #ifdef macintosh
   148 /*
   149  * translate unix-style slash-separated filename to mac-style colon-separated
   150  * name; return malloced string
   151  */
   152 static char *unix_to_mac(const char *file)
   153 {
   154 	int flen = strlen(file);
   155 	char *path = malloc(flen + 2);
   156 	const char *src = file;
   157 	char *dst = path;
   158 	if(*src == '/') {
   159 		/* really depends on filesystem layout, hope for the best */
   160 		src++;
   161 	} else {
   162 		/* Check if this is a MacOS path to begin with */
   163 		if(*src != ':')
   164 			*dst++ = ':';   /* relative paths begin with ':' */
   165 	}
   166 	while(src < file + flen) {
   167 		const char *end = strchr(src, '/');
   168 		int len;
   169 		if(!end)
   170 			end = file + flen; /* last component */
   171 		len = end - src;
   172 		if(len == 0 || (len == 1 && src[0] == '.')) {
   173 			/* remove repeated slashes and . */
   174 		} else {
   175 			if(len == 2 && src[0] == '.' && src[1] == '.') {
   176 				/* replace .. with the empty string */
   177 			} else {
   178 				memcpy(dst, src, len);
   179 				dst += len;
   180 			}
   181 			if(end < file + flen)
   182 				*dst++ = ':';
   183 		}
   184 		src = end + 1;
   185 	}
   186 	*dst++ = '\0';
   187 	return path;
   188 }
   189 #endif /* macintosh */
   190 
   191 SDL_RWops *SDL_RWFromFile(const char *file, const char *mode)
   192 {
   193 	FILE *fp;
   194 	SDL_RWops *rwops;
   195 
   196 	rwops = NULL;
   197 
   198 #ifdef macintosh
   199 	{
   200 		char *mpath = unix_to_mac(file);
   201 		fp = fopen(mpath, mode);
   202 		free(mpath);
   203 	}
   204 #else
   205 	fp = fopen(file, mode);
   206 #endif
   207 	if ( fp == NULL ) {
   208 		SDL_SetError("Couldn't open %s", file);
   209 	} else {
   210 #ifdef WIN32
   211 		in_sdl = 1;
   212 		rwops = SDL_RWFromFP(fp, 1);
   213 		in_sdl = 0;
   214 #else
   215 		rwops = SDL_RWFromFP(fp, 1);
   216 #endif
   217 	}
   218 	return(rwops);
   219 }
   220 
   221 SDL_RWops *SDL_RWFromFP(FILE *fp, int autoclose)
   222 {
   223 	SDL_RWops *rwops;
   224 
   225 #ifdef WIN32
   226 	if ( ! in_sdl ) {
   227 		SDL_SetError("You can't pass a FILE pointer to a DLL (??)");
   228 		/*return(NULL);*/
   229 	}
   230 #endif
   231 	rwops = SDL_AllocRW();
   232 	if ( rwops != NULL ) {
   233 		rwops->seek = stdio_seek;
   234 		rwops->read = stdio_read;
   235 		rwops->write = stdio_write;
   236 		rwops->close = stdio_close;
   237 		rwops->hidden.stdio.fp = fp;
   238 		rwops->hidden.stdio.autoclose = autoclose;
   239 	}
   240 	return(rwops);
   241 }
   242 
   243 SDL_RWops *SDL_RWFromMem(void *mem, int size)
   244 {
   245 	SDL_RWops *rwops;
   246 
   247 	rwops = SDL_AllocRW();
   248 	if ( rwops != NULL ) {
   249 		rwops->seek = mem_seek;
   250 		rwops->read = mem_read;
   251 		rwops->write = mem_write;
   252 		rwops->close = mem_close;
   253 		rwops->hidden.mem.base = (Uint8 *)mem;
   254 		rwops->hidden.mem.here = rwops->hidden.mem.base;
   255 		rwops->hidden.mem.stop = rwops->hidden.mem.base+size;
   256 	}
   257 	return(rwops);
   258 }
   259 
   260 SDL_RWops *SDL_AllocRW(void)
   261 {
   262 	SDL_RWops *area;
   263 
   264 	area = (SDL_RWops *)malloc(sizeof *area);
   265 	if ( area == NULL ) {
   266 		SDL_OutOfMemory();
   267 	}
   268 	return(area);
   269 }
   270 
   271 void SDL_FreeRW(SDL_RWops *area)
   272 {
   273 	free(area);
   274 }