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/*
* filer.c - open, seeks in and reads from a file
*
* Copyright (C) 2006 Thorsten Zitterell <thorsten@zitterell.de>
*/
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <pthread.h>
#include "filer.h"
/*
* function filer_getcapacity()
* returns: size/capacity of file/device
*/
unsigned long long filer_getcapacity(filer_info_t * filer_info)
{
return filer_info->size;
}
/*
* function filer_seekblock(): seek to position in file/block device
* returns: 1 on success, otherwise 0
*/
static inline int filer_seekblock(filer_info_t * filer_info, off_t newpos)
{
if (lseek(filer_info->fd, newpos, SEEK_SET) == (off_t) -1) {
return 0;
}
filer_info->pos = newpos;
return 1;
}
/*
* function filer_readblock(): read bytes at specific position
* returns: 1 on success, otherwise 0
*/
inline int filer_readblock(filer_info_t * filer_info, void *buf, size_t size,
off_t pos)
{
size_t remain = size;
int result = 0;
int numblocks = 0;
if (!filer_seekblock(filer_info, pos)) goto leave;
while (remain > 0) {
if ((numblocks = read(filer_info->fd, buf, remain)) <= 0) {
if (errno == EINTR)
continue;
goto leave;
}
if (numblocks == 0) {
goto leave;
}
remain -= numblocks;
buf += numblocks;
}
result = 1;
leave:
filer_info->pos += (size - remain);
return result;
}
/*
* function filer_init(): open file to be served
* returns: data structure with file information
*/
filer_info_t *filer_init(const char *filename)
{
filer_info_t *filer_info;
struct stat64 stbuf;
filer_info = (filer_info_t *) malloc(sizeof(filer_info_t));
if (!filer_info)
return NULL;
filer_info->filename = strdup(filename);
if ((filer_info->fd = open(filename, O_RDONLY | O_LARGEFILE)) < 0) {
fprintf(stderr, "ERROR: Cannot open filename \"%s\"\n",
filename);
goto out_free;
}
stbuf.st_size = 0;
if (fstat64(filer_info->fd, &stbuf) < 0) {
fprintf(stderr, "ERROR: Cannot stat file \"%s\"\n",
filename);
goto out_free;
}
/* get file/device size */
if ((filer_info->size = stbuf.st_size) == 0) {
filer_info->size = lseek64(filer_info->fd, (off_t) 0, SEEK_END);
}
if (filer_info->size == 0) {
fprintf(stderr, "ERROR: File/device has zero size\n");
goto out_free;
}
goto out;
out_free:
if (filer_info)
free(filer_info);
filer_info = NULL;
out:
return filer_info;
}
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