Commit | Line | Data |
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c0c3707f CB |
1 | /* Adjust a file descriptor result so that it avoids clobbering |
2 | STD{IN,OUT,ERR}_FILENO, with specific flags. | |
3 | ||
4 | Copyright (C) 2005-2006, 2009-2019 Free Software Foundation, Inc. | |
5 | ||
6 | This program is free software: you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 3 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ | |
18 | ||
19 | /* Written by Paul Eggert and Eric Blake. */ | |
20 | ||
21 | #include <config.h> | |
22 | ||
23 | /* Specification. */ | |
24 | #include "unistd-safer.h" | |
25 | ||
26 | #include <errno.h> | |
27 | #include <unistd.h> | |
28 | ||
29 | /* Return FD, unless FD would be a copy of standard input, output, or | |
30 | error; in that case, return a duplicate of FD, closing FD. If FLAG | |
31 | contains O_CLOEXEC, the returned FD will have close-on-exec | |
32 | semantics. On failure to duplicate, close FD, set errno, and | |
33 | return -1. Preserve errno if FD is negative, so that the caller | |
34 | can always inspect errno when the returned value is negative. | |
35 | ||
36 | This function is usefully wrapped around functions that return file | |
37 | descriptors, e.g., fd_safer_flag (open ("file", O_RDONLY | flag), flag). */ | |
38 | ||
39 | int | |
40 | fd_safer_flag (int fd, int flag) | |
41 | { | |
42 | if (STDIN_FILENO <= fd && fd <= STDERR_FILENO) | |
43 | { | |
44 | int f = dup_safer_flag (fd, flag); | |
45 | int e = errno; | |
46 | close (fd); | |
47 | errno = e; | |
48 | fd = f; | |
49 | } | |
50 | ||
51 | return fd; | |
52 | } |