sudo/lib/util/pread.c

49 lines
1.5 KiB
C

/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2020 Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* This is an open source non-commercial project. Dear PVS-Studio, please check it.
* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
#include <config.h>
#include <errno.h>
#include <unistd.h>
#include <sudo_compat.h>
#if !defined(HAVE_PREAD) && !defined(HAVE_PREAD64)
ssize_t
sudo_pread(int fd, void *buf, size_t nbytes, off_t offset)
{
ssize_t nread;
off_t old_offset;
old_offset = lseek(fd, (off_t)0, SEEK_CUR);
if (old_offset == -1 || lseek(fd, offset, SEEK_SET) == -1)
return -1;
nread = read(fd, buf, nbytes);
if (lseek(fd, old_offset, SEEK_SET) == -1)
return -1;
return nread;
}
#endif /* !HAVE_PREAD && !HAVE_PREAD64 */