wine/libs/port/pread.c

54 lines
1.5 KiB
C

/*
* pread function
*
* Copyright 1996 Alexandre Julliard
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "config.h"
#include "wine/port.h"
#include <errno.h>
#include <stdio.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#ifdef HAVE_IO_H
# include <io.h>
#endif
/* FIXME: this is not thread-safe */
#ifndef HAVE_PREAD
ssize_t pread( int fd, void *buf, size_t count, off_t offset )
{
ssize_t ret;
off_t old_pos;
if ((old_pos = lseek( fd, 0, SEEK_CUR )) == -1) return -1;
if (lseek( fd, offset, SEEK_SET ) == -1) return -1;
if ((ret = read( fd, buf, count )) == -1)
{
int err = errno; /* save errno */
lseek( fd, old_pos, SEEK_SET );
errno = err;
return -1;
}
if (lseek( fd, old_pos, SEEK_SET ) == -1) return -1;
return ret;
}
#endif /* HAVE_PREAD */