1 | /* cloexec.c - set or clear the close-on-exec descriptor flag |
2 | |
3 | Copyright (C) 1991, 2004-2006, 2009-2019 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 <https://www.gnu.org/licenses/>. |
17 | |
18 | The code is taken from glibc/manual/llio.texi */ |
19 | |
20 | #include <config.h> |
21 | |
22 | #include "cloexec.h" |
23 | |
24 | #include <errno.h> |
25 | #include <fcntl.h> |
26 | #include <unistd.h> |
27 | |
28 | /* Set the 'FD_CLOEXEC' flag of DESC if VALUE is true, |
29 | or clear the flag if VALUE is false. |
30 | Return 0 on success, or -1 on error with 'errno' set. |
31 | |
32 | Note that on MingW, this function does NOT protect DESC from being |
33 | inherited into spawned children. Instead, either use dup_cloexec |
34 | followed by closing the original DESC, or use interfaces such as |
35 | open or pipe2 that accept flags like O_CLOEXEC to create DESC |
36 | non-inheritable in the first place. */ |
37 | |
38 | int |
39 | set_cloexec_flag (int desc, bool value) |
40 | { |
41 | #ifdef F_SETFD |
42 | |
43 | int flags = fcntl (desc, F_GETFD, 0); |
44 | |
45 | if (0 <= flags) |
46 | { |
47 | int newflags = (value ? flags | FD_CLOEXEC : flags & ~FD_CLOEXEC); |
48 | |
49 | if (flags == newflags |
50 | || fcntl (desc, F_SETFD, newflags) != -1) |
51 | return 0; |
52 | } |
53 | |
54 | return -1; |
55 | |
56 | #else /* !F_SETFD */ |
57 | |
58 | /* Use dup2 to reject invalid file descriptors; the cloexec flag |
59 | will be unaffected. */ |
60 | if (desc < 0) |
61 | { |
62 | errno = EBADF; |
63 | return -1; |
64 | } |
65 | if (dup2 (desc, desc) < 0) |
66 | /* errno is EBADF here. */ |
67 | return -1; |
68 | |
69 | /* There is nothing we can do on this kind of platform. Punt. */ |
70 | return 0; |
71 | #endif /* !F_SETFD */ |
72 | } |
73 | |
74 | |
75 | /* Duplicates a file handle FD, while marking the copy to be closed |
76 | prior to exec or spawn. Returns -1 and sets errno if FD could not |
77 | be duplicated. */ |
78 | |
79 | int |
80 | dup_cloexec (int fd) |
81 | { |
82 | return fcntl (fd, F_DUPFD_CLOEXEC, 0); |
83 | } |
84 | |