mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-29 05:51:10 +00:00
1c6d89e9a4
* io/read.c (read): Add libc_hidden_weak. * sysdeps/mach/hurd/read.c (read): Likewise. * io/write.c (write): Likewise. * sysdeps/mach/hurd/write.c (write): Likewise. * io/pread64.c (__pread64): Likewise. * sysdeps/mach/hurd/pread64.c (__pread64): Likewise. * posix/pread64.c (__pread64): Add libc_hidden_def.
64 lines
2.0 KiB
C
64 lines
2.0 KiB
C
/* Read block from given position in file without changing file pointer.
|
|
POSIX version.
|
|
Copyright (C) 1997-2017 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
|
|
|
|
The GNU C 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.
|
|
|
|
The GNU C 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 the GNU C Library; if not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#include <errno.h>
|
|
#include <unistd.h>
|
|
|
|
/* Note: This implementation of pread64 is not multithread-safe. */
|
|
|
|
ssize_t
|
|
__libc_pread64 (int fd, void *buf, size_t nbyte, off64_t offset)
|
|
{
|
|
/* Since we must not change the file pointer preserve the value so that
|
|
we can restore it later. */
|
|
int save_errno;
|
|
ssize_t result;
|
|
off64_t old_offset = __libc_lseek64 (fd, 0, SEEK_CUR);
|
|
if (old_offset == (off64_t) -1)
|
|
return -1;
|
|
|
|
/* Set to wanted position. */
|
|
if (__libc_lseek64 (fd, offset, SEEK_SET) == (off64_t) -1)
|
|
return -1;
|
|
|
|
/* Write out the data. */
|
|
result = __libc_read (fd, buf, nbyte);
|
|
|
|
/* Now we have to restore the position. If this fails we have to
|
|
return this as an error. But if the writing also failed we
|
|
return this error. */
|
|
save_errno = errno;
|
|
if (__libc_lseek64 (fd, old_offset, SEEK_SET) == (off64_t) -1)
|
|
{
|
|
if (result == -1)
|
|
__set_errno (save_errno);
|
|
return -1;
|
|
}
|
|
__set_errno (save_errno);
|
|
|
|
return result;
|
|
}
|
|
|
|
#ifndef __libc_pread64
|
|
weak_alias (__libc_pread64, __pread64)
|
|
libc_hidden_weak (__pread64)
|
|
weak_alias (__libc_pread64, pread64)
|
|
#endif
|