src/file/SDL_rwops.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2011 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#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 __APPLE__
#include "cocoa/SDL_rwopsbundlesupport.h"
#endif /* __APPLE__ */

#ifdef __NDS__
/* include libfat headers for fatInitDefault(). */
#include <fat.h>
#endif /* __NDS__ */

#ifdef __WIN32__

/* Functions to read/write Win32 API file pointers */
/* Will not use it on WinCE because stdio is buffered, it means
   faster, and all stdio functions anyway are embedded in coredll.dll - 
   the main wince dll*/

#include "../core/windows/SDL_windows.h"

#ifndef INVALID_SET_FILE_POINTER
#define INVALID_SET_FILE_POINTER 0xFFFFFFFF
#endif

#define READAHEAD_BUFFER_SIZE	1024

static int SDLCALL
windows_file_open(SDL_RWops * context, const char *filename, const char *mode)
{
#ifndef _WIN32_WCE
    UINT old_error_mode;
#endif
    HANDLE h;
    DWORD r_right, w_right;
    DWORD must_exist, truncate;
    int a_mode;

    if (!context)
        return -1;              /* failed (invalid call) */

    context->hidden.windowsio.h = INVALID_HANDLE_VALUE;   /* mark this as unusable */
    context->hidden.windowsio.buffer.data = NULL;
    context->hidden.windowsio.buffer.size = 0;
    context->hidden.windowsio.buffer.left = 0;

    /* "r" = reading, file must exist */
    /* "w" = writing, truncate existing, file may not exist */
    /* "r+"= reading or writing, file must exist            */
    /* "a" = writing, append file may not exist             */
    /* "a+"= append + read, file may not exist              */
    /* "w+" = read, write, truncate. file may not exist    */

    must_exist = (SDL_strchr(mode, 'r') != NULL) ? OPEN_EXISTING : 0;
    truncate = (SDL_strchr(mode, 'w') != NULL) ? CREATE_ALWAYS : 0;
    r_right = (SDL_strchr(mode, '+') != NULL
               || must_exist) ? GENERIC_READ : 0;
    a_mode = (SDL_strchr(mode, 'a') != NULL) ? OPEN_ALWAYS : 0;
    w_right = (a_mode || SDL_strchr(mode, '+')
               || truncate) ? GENERIC_WRITE : 0;

    if (!r_right && !w_right)   /* inconsistent mode */
        return -1;              /* failed (invalid call) */

    context->hidden.windowsio.buffer.data =
        (char *) SDL_malloc(READAHEAD_BUFFER_SIZE);
    if (!context->hidden.windowsio.buffer.data) {
        SDL_OutOfMemory();
        return -1;
    }
#ifdef _WIN32_WCE
    {
        LPTSTR tstr = WIN_UTF8ToString(filename);
        h = CreateFile(tstr, (w_right | r_right),
                       (w_right) ? 0 : FILE_SHARE_READ, NULL,
                       (must_exist | truncate | a_mode),
                       FILE_ATTRIBUTE_NORMAL, NULL);
        SDL_free(tstr);
    }
#else
    /* Do not open a dialog box if failure */
    old_error_mode =
        SetErrorMode(SEM_NOOPENFILEERRORBOX | SEM_FAILCRITICALERRORS);

    {
        LPTSTR tstr = WIN_UTF8ToString(filename);
        h = CreateFile(tstr, (w_right | r_right),
                       (w_right) ? 0 : FILE_SHARE_READ, NULL,
                       (must_exist | truncate | a_mode),
                       FILE_ATTRIBUTE_NORMAL, NULL);
        SDL_free(tstr);
    }

    /* restore old behavior */
    SetErrorMode(old_error_mode);
#endif /* _WIN32_WCE */

    if (h == INVALID_HANDLE_VALUE) {
        SDL_free(context->hidden.windowsio.buffer.data);
        context->hidden.windowsio.buffer.data = NULL;
        SDL_SetError("Couldn't open %s", filename);
        return -2;              /* failed (CreateFile) */
    }
    context->hidden.windowsio.h = h;
    context->hidden.windowsio.append = a_mode ? SDL_TRUE : SDL_FALSE;

    return 0;                   /* ok */
}

static long SDLCALL
windows_file_seek(SDL_RWops * context, long offset, int whence)
{
    DWORD windowswhence;
    long file_pos;

    if (!context || context->hidden.windowsio.h == INVALID_HANDLE_VALUE) {
        SDL_SetError("windows_file_seek: invalid context/file not opened");
        return -1;
    }

    /* FIXME: We may be able to satisfy the seek within buffered data */
    if (whence == RW_SEEK_CUR && context->hidden.windowsio.buffer.left) {
        offset -= (long)context->hidden.windowsio.buffer.left;
    }
    context->hidden.windowsio.buffer.left = 0;

    switch (whence) {
    case RW_SEEK_SET:
        windowswhence = FILE_BEGIN;
        break;
    case RW_SEEK_CUR:
        windowswhence = FILE_CURRENT;
        break;
    case RW_SEEK_END:
        windowswhence = FILE_END;
        break;
    default:
        SDL_SetError("windows_file_seek: Unknown value for 'whence'");
        return -1;
    }

    file_pos =
        SetFilePointer(context->hidden.windowsio.h, offset, NULL, windowswhence);

    if (file_pos != INVALID_SET_FILE_POINTER)
        return file_pos;        /* success */

    SDL_Error(SDL_EFSEEK);
    return -1;                  /* error */
}

static size_t SDLCALL
windows_file_read(SDL_RWops * context, void *ptr, size_t size, size_t maxnum)
{
    size_t total_need;
    size_t total_read = 0;
    size_t read_ahead;
    DWORD byte_read;

    total_need = size * maxnum;

    if (!context || context->hidden.windowsio.h == INVALID_HANDLE_VALUE
        || !total_need)
        return 0;

    if (context->hidden.windowsio.buffer.left > 0) {
        void *data = (char *) context->hidden.windowsio.buffer.data +
            context->hidden.windowsio.buffer.size -
            context->hidden.windowsio.buffer.left;
        read_ahead =
            SDL_min(total_need, context->hidden.windowsio.buffer.left);
        SDL_memcpy(ptr, data, read_ahead);
        context->hidden.windowsio.buffer.left -= read_ahead;

        if (read_ahead == total_need) {
            return maxnum;
        }
        ptr = (char *) ptr + read_ahead;
        total_need -= read_ahead;
        total_read += read_ahead;
    }

    if (total_need < READAHEAD_BUFFER_SIZE) {
        if (!ReadFile
            (context->hidden.windowsio.h, context->hidden.windowsio.buffer.data,
             READAHEAD_BUFFER_SIZE, &byte_read, NULL)) {
            SDL_Error(SDL_EFREAD);
            return 0;
        }
        read_ahead = SDL_min(total_need, (int) byte_read);
        SDL_memcpy(ptr, context->hidden.windowsio.buffer.data, read_ahead);
        context->hidden.windowsio.buffer.size = byte_read;
        context->hidden.windowsio.buffer.left = byte_read - read_ahead;
        total_read += read_ahead;
    } else {
        if (!ReadFile
            (context->hidden.windowsio.h, ptr, (DWORD)total_need, &byte_read, NULL)) {
            SDL_Error(SDL_EFREAD);
            return 0;
        }
        total_read += byte_read;
    }
    return (total_read / size);
}

static size_t SDLCALL
windows_file_write(SDL_RWops * context, const void *ptr, size_t size,
                 size_t num)
{

    size_t total_bytes;
    DWORD byte_written;
    size_t nwritten;

    total_bytes = size * num;

    if (!context || context->hidden.windowsio.h == INVALID_HANDLE_VALUE
        || total_bytes <= 0 || !size)
        return 0;

    if (context->hidden.windowsio.buffer.left) {
        SetFilePointer(context->hidden.windowsio.h,
                       -(LONG)context->hidden.windowsio.buffer.left, NULL,
                       FILE_CURRENT);
        context->hidden.windowsio.buffer.left = 0;
    }

    /* if in append mode, we must go to the EOF before write */
    if (context->hidden.windowsio.append) {
        if (SetFilePointer(context->hidden.windowsio.h, 0L, NULL, FILE_END) ==
            INVALID_SET_FILE_POINTER) {
            SDL_Error(SDL_EFWRITE);
            return 0;
        }
    }

    if (!WriteFile
        (context->hidden.windowsio.h, ptr, (DWORD)total_bytes, &byte_written, NULL)) {
        SDL_Error(SDL_EFWRITE);
        return 0;
    }

    nwritten = byte_written / size;
    return nwritten;
}

static int SDLCALL
windows_file_close(SDL_RWops * context)
{

    if (context) {
        if (context->hidden.windowsio.h != INVALID_HANDLE_VALUE) {
            CloseHandle(context->hidden.windowsio.h);
            context->hidden.windowsio.h = INVALID_HANDLE_VALUE;   /* to be sure */
        }
        if (context->hidden.windowsio.buffer.data) {
            SDL_free(context->hidden.windowsio.buffer.data);
            context->hidden.windowsio.buffer.data = NULL;
        }
        SDL_FreeRW(context);
    }
    return (0);
}
#endif /* __WIN32__ */

#ifdef HAVE_STDIO_H

/* Functions to read/write stdio file pointers */

static long SDLCALL
stdio_seek(SDL_RWops * context, long 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 size_t SDLCALL
stdio_read(SDL_RWops * context, void *ptr, size_t size, size_t 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 size_t SDLCALL
stdio_write(SDL_RWops * context, const void *ptr, size_t size, size_t 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 SDLCALL
stdio_close(SDL_RWops * context)
{
    int status = 0;
    if (context) {
        if (context->hidden.stdio.autoclose) {
            /* WARNING:  Check the return value here! */
            if (fclose(context->hidden.stdio.fp) != 0) {
                SDL_Error(SDL_EFWRITE);
                status = -1;
            }
        }
        SDL_FreeRW(context);
    }
    return status;
}
#endif /* !HAVE_STDIO_H */

/* Functions to read/write memory pointers */

static long SDLCALL
mem_seek(SDL_RWops * context, long 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 (long)(context->hidden.mem.here - context->hidden.mem.base);
}

static size_t SDLCALL
mem_read(SDL_RWops * context, void *ptr, size_t size, size_t maxnum)
{
    size_t total_bytes;
    size_t mem_available;

    total_bytes = (maxnum * size);
    if ((maxnum <= 0) || (size <= 0)
        || ((total_bytes / maxnum) != (size_t) 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 size_t SDLCALL
mem_write(SDL_RWops * context, const void *ptr, size_t size, size_t 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 size_t SDLCALL
mem_writeconst(SDL_RWops * context, const void *ptr, size_t size, size_t num)
{
    SDL_SetError("Can't write to read-only memory");
    return (-1);
}

static int SDLCALL
mem_close(SDL_RWops * context)
{
    if (context) {
        SDL_FreeRW(context);
    }
    return (0);
}


/* Functions to create SDL_RWops structures from various data sources */

SDL_RWops *
SDL_RWFromFile(const char *file, const char *mode)
{
    SDL_RWops *rwops = NULL;
#ifdef HAVE_STDIO_H
    FILE *fp = NULL;
#endif
    if (!file || !*file || !mode || !*mode) {
        SDL_SetError("SDL_RWFromFile(): No file or no mode specified");
        return NULL;
    }
#if defined(__WIN32__)
    rwops = SDL_AllocRW();
    if (!rwops)
        return NULL;            /* SDL_SetError already setup by SDL_AllocRW() */
    if (windows_file_open(rwops, file, mode) < 0) {
        SDL_FreeRW(rwops);
        return NULL;
    }
    rwops->seek = windows_file_seek;
    rwops->read = windows_file_read;
    rwops->write = windows_file_write;
    rwops->close = windows_file_close;

#elif HAVE_STDIO_H
	#ifdef __APPLE__
	fp = SDL_OpenFPFromBundleOrFallback(file, mode);
    #else
	fp = fopen(file, mode);
	#endif
	if (fp == NULL) {
        SDL_SetError("Couldn't open %s", file);
    } else {
        rwops = SDL_RWFromFP(fp, 1);
    }
#else
    SDL_SetError("SDL not compiled with stdio support");
#endif /* !HAVE_STDIO_H */

    return (rwops);
}

#ifdef HAVE_STDIO_H
SDL_RWops *
SDL_RWFromFP(FILE * fp, SDL_bool autoclose)
{
    SDL_RWops *rwops = NULL;

#if 0
/*#ifdef __NDS__*/
    /* set it up so we can use stdio file function */
    fatInitDefault();
    printf("called fatInitDefault()");
#endif /* __NDS__ */

    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);
}
#else
SDL_RWops *
SDL_RWFromFP(void * fp, SDL_bool autoclose)
{
    SDL_SetError("SDL not compiled with stdio support");
    return NULL;
}
#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);
    return (SDL_SwapBE64(value));
}

size_t
SDL_WriteLE16(SDL_RWops * dst, Uint16 value)
{
    value = SDL_SwapLE16(value);
    return (SDL_RWwrite(dst, &value, (sizeof value), 1));
}

size_t
SDL_WriteBE16(SDL_RWops * dst, Uint16 value)
{
    value = SDL_SwapBE16(value);
    return (SDL_RWwrite(dst, &value, (sizeof value), 1));
}

size_t
SDL_WriteLE32(SDL_RWops * dst, Uint32 value)
{
    value = SDL_SwapLE32(value);
    return (SDL_RWwrite(dst, &value, (sizeof value), 1));
}

size_t
SDL_WriteBE32(SDL_RWops * dst, Uint32 value)
{
    value = SDL_SwapBE32(value);
    return (SDL_RWwrite(dst, &value, (sizeof value), 1));
}

size_t
SDL_WriteLE64(SDL_RWops * dst, Uint64 value)
{
    value = SDL_SwapLE64(value);
    return (SDL_RWwrite(dst, &value, (sizeof value), 1));
}

size_t
SDL_WriteBE64(SDL_RWops * dst, Uint64 value)
{
    value = SDL_SwapBE64(value);
    return (SDL_RWwrite(dst, &value, (sizeof value), 1));
}

/* vi: set ts=4 sw=4 expandtab: */