SDL_rwops.c
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/*
SDL - Simple DirectMedia Layer
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Copyright (C) 1997-2004 Sam Lantinga
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This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Sam Lantinga
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slouken@libsdl.org
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*/
#ifdef SAVE_RCSID
static char rcsid =
"@(#) $Id$";
#endif
/* This file provides a general interface for SDL to read and write
data sources. It can easily be extended to files, memory, etc.
*/
#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
#include "SDL_error.h"
#include "SDL_rwops.h"
/* Functions to read/write stdio file pointers */
static int stdio_seek(SDL_RWops *context, int offset, int whence)
{
if ( fseek(context->hidden.stdio.fp, offset, whence) == 0 ) {
return(ftell(context->hidden.stdio.fp));
} else {
SDL_Error(SDL_EFSEEK);
return(-1);
}
}
static int stdio_read(SDL_RWops *context, void *ptr, int size, int maxnum)
{
size_t nread;
nread = fread(ptr, size, maxnum, context->hidden.stdio.fp);
if ( nread == 0 && ferror(context->hidden.stdio.fp) ) {
SDL_Error(SDL_EFREAD);
}
return(nread);
}
static int stdio_write(SDL_RWops *context, const void *ptr, int size, int num)
{
size_t nwrote;
nwrote = fwrite(ptr, size, num, context->hidden.stdio.fp);
if ( nwrote == 0 && ferror(context->hidden.stdio.fp) ) {
SDL_Error(SDL_EFWRITE);
}
return(nwrote);
}
static int stdio_close(SDL_RWops *context)
{
if ( context ) {
if ( context->hidden.stdio.autoclose ) {
/* WARNING: Check the return value here! */
fclose(context->hidden.stdio.fp);
}
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SDL_FreeRW(context);
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}
return(0);
}
/* Functions to read/write memory pointers */
static int mem_seek(SDL_RWops *context, int offset, int whence)
{
Uint8 *newpos;
switch (whence) {
case SEEK_SET:
newpos = context->hidden.mem.base+offset;
break;
case SEEK_CUR:
newpos = context->hidden.mem.here+offset;
break;
case SEEK_END:
newpos = context->hidden.mem.stop+offset;
break;
default:
SDL_SetError("Unknown value for 'whence'");
return(-1);
}
if ( newpos < context->hidden.mem.base ) {
newpos = context->hidden.mem.base;
}
if ( newpos > context->hidden.mem.stop ) {
newpos = context->hidden.mem.stop;
}
context->hidden.mem.here = newpos;
return(context->hidden.mem.here-context->hidden.mem.base);
}
static int mem_read(SDL_RWops *context, void *ptr, int size, int maxnum)
{
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int total_bytes;
int mem_available;
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total_bytes = (maxnum * size);
if ( (maxnum <= 0) || (size <= 0) || ((total_bytes / maxnum) != size) ) {
return 0;
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}
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mem_available = (context->hidden.mem.stop - context->hidden.mem.here);
if (total_bytes > mem_available) {
total_bytes = mem_available;
}
memcpy(ptr, context->hidden.mem.here, total_bytes);
context->hidden.mem.here += total_bytes;
return (total_bytes / size);
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}
static int mem_write(SDL_RWops *context, const void *ptr, int size, int num)
{
if ( (context->hidden.mem.here + (num*size)) > context->hidden.mem.stop ) {
num = (context->hidden.mem.stop-context->hidden.mem.here)/size;
}
memcpy(context->hidden.mem.here, ptr, num*size);
context->hidden.mem.here += num*size;
return(num);
}
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static int mem_writeconst(SDL_RWops *context, const void *ptr, int size, int num)
{
SDL_SetError("Can't write to read-only memory");
return(-1);
}
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static int mem_close(SDL_RWops *context)
{
if ( context ) {
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SDL_FreeRW(context);
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}
return(0);
}
/* Functions to create SDL_RWops structures from various data sources */
#ifdef WIN32
/* Aggh. You can't (apparently) open a file in an application and
read from it in a DLL.
*/
static int in_sdl = 0;
#endif
#ifdef macintosh
/*
* translate unix-style slash-separated filename to mac-style colon-separated
* name; return malloced string
*/
static char *unix_to_mac(const char *file)
{
int flen = strlen(file);
char *path = malloc(flen + 2);
const char *src = file;
char *dst = path;
if(*src == '/') {
/* really depends on filesystem layout, hope for the best */
src++;
} else {
/* Check if this is a MacOS path to begin with */
if(*src != ':')
*dst++ = ':'; /* relative paths begin with ':' */
}
while(src < file + flen) {
const char *end = strchr(src, '/');
int len;
if(!end)
end = file + flen; /* last component */
len = end - src;
if(len == 0 || (len == 1 && src[0] == '.')) {
/* remove repeated slashes and . */
} else {
if(len == 2 && src[0] == '.' && src[1] == '.') {
/* replace .. with the empty string */
} else {
memcpy(dst, src, len);
dst += len;
}
if(end < file + flen)
*dst++ = ':';
}
src = end + 1;
}
*dst++ = '\0';
return path;
}
#endif /* macintosh */
SDL_RWops *SDL_RWFromFile(const char *file, const char *mode)
{
FILE *fp;
SDL_RWops *rwops;
rwops = NULL;
#ifdef macintosh
{
char *mpath = unix_to_mac(file);
fp = fopen(mpath, mode);
free(mpath);
}
#else
fp = fopen(file, mode);
#endif
if ( fp == NULL ) {
SDL_SetError("Couldn't open %s", file);
} else {
#ifdef WIN32
in_sdl = 1;
rwops = SDL_RWFromFP(fp, 1);
in_sdl = 0;
#else
rwops = SDL_RWFromFP(fp, 1);
#endif
}
return(rwops);
}
SDL_RWops *SDL_RWFromFP(FILE *fp, int autoclose)
{
SDL_RWops *rwops;
#ifdef WIN32
if ( ! in_sdl ) {
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/* It's when SDL and the app are compiled with different C runtimes */
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SDL_SetError("You can't pass a FILE pointer to a DLL (?)");
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/*return(NULL);*/
}
#endif
rwops = SDL_AllocRW();
if ( rwops != NULL ) {
rwops->seek = stdio_seek;
rwops->read = stdio_read;
rwops->write = stdio_write;
rwops->close = stdio_close;
rwops->hidden.stdio.fp = fp;
rwops->hidden.stdio.autoclose = autoclose;
}
return(rwops);
}
SDL_RWops *SDL_RWFromMem(void *mem, int size)
{
SDL_RWops *rwops;
rwops = SDL_AllocRW();
if ( rwops != NULL ) {
rwops->seek = mem_seek;
rwops->read = mem_read;
rwops->write = mem_write;
rwops->close = mem_close;
rwops->hidden.mem.base = (Uint8 *)mem;
rwops->hidden.mem.here = rwops->hidden.mem.base;
rwops->hidden.mem.stop = rwops->hidden.mem.base+size;
}
return(rwops);
}
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SDL_RWops *SDL_RWFromConstMem(const void *mem, int size)
{
SDL_RWops *rwops;
rwops = SDL_AllocRW();
if ( rwops != NULL ) {
rwops->seek = mem_seek;
rwops->read = mem_read;
rwops->write = mem_writeconst;
rwops->close = mem_close;
rwops->hidden.mem.base = (Uint8 *)mem;
rwops->hidden.mem.here = rwops->hidden.mem.base;
rwops->hidden.mem.stop = rwops->hidden.mem.base+size;
}
return(rwops);
}
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SDL_RWops *SDL_AllocRW(void)
{
SDL_RWops *area;
area = (SDL_RWops *)malloc(sizeof *area);
if ( area == NULL ) {
SDL_OutOfMemory();
}
return(area);
}
void SDL_FreeRW(SDL_RWops *area)
{
free(area);
}