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//
// Copyright(C) 1993-1996 Id Software, Inc.
// Copyright(C) 2005-2014 Simon Howard
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// DESCRIPTION:
// WAD I/O functions.
//
#include "config.h"
#ifdef HAVE_MMAP
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <string.h>
#include "w_file.h"
#include "z_zone.h"
typedef struct
{
wad_file_t wad;
int handle;
} posix_wad_file_t;
extern wad_file_class_t posix_wad_file;
static void MapFile(posix_wad_file_t *wad, char *filename)
{
void *result;
int protection;
int flags;
// Mapped area can be read and written to. Ideally
// this should be read-only, as none of the Doom code should
// change the WAD files after being read. However, there may
// be code lurking in the source that does.
protection = PROT_READ|PROT_WRITE;
// Writes to the mapped area result in private changes that are
// *not* written to disk.
flags = MAP_PRIVATE;
result = mmap(NULL, wad->wad.length,
protection, flags,
wad->handle, 0);
wad->wad.mapped = result;
if (result == NULL)
{
fprintf(stderr, "W_POSIX_OpenFile: Unable to mmap() %s - %s\n",
filename, strerror(errno));
}
}
unsigned int GetFileLength(int handle)
{
return lseek(handle, 0, SEEK_END);
}
static wad_file_t *W_POSIX_OpenFile(char *path)
{
posix_wad_file_t *result;
int handle;
handle = open(path, 0);
if (handle < 0)
{
return NULL;
}
// Create a new posix_wad_file_t to hold the file handle.
result = Z_Malloc(sizeof(posix_wad_file_t), PU_STATIC, 0);
result->wad.file_class = &posix_wad_file;
result->wad.length = GetFileLength(handle);
result->handle = handle;
// Try to map the file into memory with mmap:
MapFile(result, path);
return &result->wad;
}
static void W_POSIX_CloseFile(wad_file_t *wad)
{
posix_wad_file_t *posix_wad;
posix_wad = (posix_wad_file_t *) wad;
// If mapped, unmap it.
// Close the file
close(posix_wad->handle);
Z_Free(posix_wad);
}
// Read data from the specified position in the file into the
// provided buffer. Returns the number of bytes read.
size_t W_POSIX_Read(wad_file_t *wad, unsigned int offset,
void *buffer, size_t buffer_len)
{
posix_wad_file_t *posix_wad;
byte *byte_buffer;
size_t bytes_read;
int result;
posix_wad = (posix_wad_file_t *) wad;
// Jump to the specified position in the file.
lseek(posix_wad->handle, offset, SEEK_SET);
// Read into the buffer.
bytes_read = 0;
byte_buffer = buffer;
while (buffer_len > 0) {
result = read(posix_wad->handle, byte_buffer, buffer_len);
if (result < 0) {
perror("W_POSIX_Read");
break;
} else if (result == 0) {
break;
}
// Successfully read some bytes
byte_buffer += result;
buffer_len -= result;
bytes_read += result;
}
return bytes_read;
}
wad_file_class_t posix_wad_file =
{
W_POSIX_OpenFile,
W_POSIX_CloseFile,
W_POSIX_Read,
};
#endif /* #ifdef HAVE_MMAP */
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