Line data Source code
1 : /* Invoke open, but return either a desired file descriptor or -1.
2 :
3 : Copyright (C) 2005, 2006, 2008 Free Software Foundation, Inc.
4 :
5 : This program is free software: you can redistribute it and/or modify
6 : it under the terms of the GNU General Public License as published by
7 : the Free Software Foundation, either version 3 of the License, or
8 : (at your option) any later version.
9 :
10 : This program is distributed in the hope that it will be useful,
11 : but WITHOUT ANY WARRANTY; without even the implied warranty of
12 : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 : GNU General Public License for more details.
14 :
15 : You should have received a copy of the GNU General Public License
16 : along with this program. If not, see <http://www.gnu.org/licenses/>. */
17 :
18 : /* Written by Paul Eggert. */
19 :
20 : #include <config.h>
21 :
22 : #include "fd-reopen.h"
23 :
24 : #include <errno.h>
25 : #include <fcntl.h>
26 : #include <unistd.h>
27 :
28 : /* Open a file to a particular file descriptor. This is like standard
29 : `open', except it always returns DESIRED_FD if successful. */
30 :
31 : int
32 77 : fd_reopen (int desired_fd, char const *file, int flags, mode_t mode)
33 : {
34 77 : int fd = open (file, flags, mode);
35 :
36 77 : if (fd == desired_fd || fd < 0)
37 32 : return fd;
38 : else
39 : {
40 45 : int fd2 = dup2 (fd, desired_fd);
41 45 : int saved_errno = errno;
42 45 : close (fd);
43 45 : errno = saved_errno;
44 45 : return fd2;
45 : }
46 : }
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