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/* Invoke open, but return either a desired file descriptor or -1.
Copyright (C) 2005-2023 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Paul Eggert. */
#include <config.h>
#include "fd-reopen.h"
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
/* Open a file to a particular file descriptor. This is like standard
'open', except it always returns DESIRED_FD if successful. */
int
fd_reopen (int desired_fd, char const *file, int flags, mode_t mode)
{
int fd = open (file, flags, mode);
if (fd == desired_fd || fd < 0)
return fd;
else
{
int fd2 = dup2 (fd, desired_fd);
int saved_errno = errno;
close (fd);
errno = saved_errno;
return fd2;
}
}
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