glibc/sysdeps/posix/pread64.c
Siddhesh Poyarekar 30891f35fa Remove "Contributed by" lines
We stopped adding "Contributed by" or similar lines in sources in 2012
in favour of git logs and keeping the Contributors section of the
glibc manual up to date.  Removing these lines makes the license
header a bit more consistent across files and also removes the
possibility of error in attribution when license blocks or files are
copied across since the contributed-by lines don't actually reflect
reality in those cases.

Move all "Contributed by" and similar lines (Written by, Test by,
etc.) into a new file CONTRIBUTED-BY to retain record of these
contributions.  These contributors are also mentioned in
manual/contrib.texi, so we just maintain this additional record as a
courtesy to the earlier developers.

The following scripts were used to filter a list of files to edit in
place and to clean up the CONTRIBUTED-BY file respectively.  These
were not added to the glibc sources because they're not expected to be
of any use in future given that this is a one time task:

https://gist.github.com/siddhesh/b5ecac94eabfd72ed2916d6d8157e7dc
https://gist.github.com/siddhesh/15ea1f5e435ace9774f485030695ee02

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2021-09-03 22:06:44 +05:30

63 lines
2.0 KiB
C

/* Read block from given position in file without changing file pointer.
POSIX version.
Copyright (C) 1997-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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
<https://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