/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2006 Sam Lantinga

    This library is free software; you can redistribute it and/or

    modify it under the terms of the GNU Lesser General Public

    License as published by the Free Software Foundation; either

    version 2.1 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

    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public

    License along with this library; if not, write to the Free Software

    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga

    slouken@libsdl.org

*/

#include "SDL_config.h"

/* This file provides a general interface for SDL to read and write

   data sources.  It can easily be extended to files, memory, etc.

*/

#include "SDL_endian.h"

#include "SDL_rwops.h"

#ifdef HAVE_STDIO_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);

		}

		SDL_FreeRW(context);

	}

	return(0);

}

/* Functions to read/write memory pointers */

static int mem_seek(SDL_RWops *context, int offset, int whence)

{

	Uint8 *newpos;

	switch (whence) {

		case RW_SEEK_SET:

			newpos = context->hidden.mem.base+offset;

			break;

		case RW_SEEK_CUR:

			newpos = context->hidden.mem.here+offset;

			break;

		case RW_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)

{

	int total_bytes;

	int mem_available;

	total_bytes = (maxnum * size);

	if ( (maxnum <= 0) || (size <= 0) || ((total_bytes / maxnum) != size) ) {

		return 0;

	}

	mem_available = (context->hidden.mem.stop - context->hidden.mem.here);

	if (total_bytes > mem_available) {

		total_bytes = mem_available;

	}

	SDL_memcpy(ptr, context->hidden.mem.here, total_bytes);

	context->hidden.mem.here += total_bytes;

	return (total_bytes / size);

}

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;

	}

	SDL_memcpy(context->hidden.mem.here, ptr, num*size);

	context->hidden.mem.here += num*size;

	return(num);

}

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);

}

static int mem_close(SDL_RWops *context)

{

	if ( context ) {

		SDL_FreeRW(context);

	}

	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 __MACOS__

/*

 * 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 = SDL_strlen(file);

	char *path = SDL_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 = SDL_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 {

				SDL_memcpy(dst, src, len);

				dst += len;

			}

			if(end < file + flen)

				*dst++ = ':';

		}

		src = end + 1;

	}

	*dst++ = '\0';

	return path;

}

#endif /* __MACOS__ */

SDL_RWops *SDL_RWFromFile(const char *file, const char *mode)

{

	SDL_RWops *rwops = NULL;

#ifdef HAVE_STDIO_H

	FILE *fp;

#ifdef __MACOS__

	{

		char *mpath = unix_to_mac(file);

		fp = fopen(mpath, mode);

		SDL_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);

}

#ifdef HAVE_STDIO_H

SDL_RWops *SDL_RWFromFP(FILE *fp, int autoclose)

{

	SDL_RWops *rwops = NULL;

#ifdef __WIN32__

	if ( ! in_sdl ) {

		/* It's when SDL and the app are compiled with different C runtimes */

		SDL_SetError("You can't pass a FILE pointer to a DLL (?)");

		/*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);

}

#endif /* HAVE_STDIO_H */

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);

}

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);

}

SDL_RWops *SDL_AllocRW(void)

{

	SDL_RWops *area;

	area = (SDL_RWops *)SDL_malloc(sizeof *area);

	if ( area == NULL ) {

		SDL_OutOfMemory();

	}

	return(area);

}

void SDL_FreeRW(SDL_RWops *area)

{

	SDL_free(area);

}

/* Functions for dynamically reading and writing endian-specific values */

Uint16 SDL_ReadLE16 (SDL_RWops *src)

{

	Uint16 value;

	SDL_RWread(src, &value, (sizeof value), 1);

	return(SDL_SwapLE16(value));

}

Uint16 SDL_ReadBE16 (SDL_RWops *src)

{

	Uint16 value;

	SDL_RWread(src, &value, (sizeof value), 1);

	return(SDL_SwapBE16(value));

}

Uint32 SDL_ReadLE32 (SDL_RWops *src)

{

	Uint32 value;

	SDL_RWread(src, &value, (sizeof value), 1);

	return(SDL_SwapLE32(value));

}

Uint32 SDL_ReadBE32 (SDL_RWops *src)

{

	Uint32 value;

	SDL_RWread(src, &value, (sizeof value), 1);

	return(SDL_SwapBE32(value));

}

Uint64 SDL_ReadLE64 (SDL_RWops *src)

{

	Uint64 value;

	SDL_RWread(src, &value, (sizeof value), 1);

	return(SDL_SwapLE64(value));

}

Uint64 SDL_ReadBE64 (SDL_RWops *src)

{

	Uint64 value;

	SDL_RWread(src, &value, (sizeof value), 1);