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7a6dbc2f | 1 | /* cloexec.c - set or clear the close-on-exec descriptor flag |
6ec2e0f5 | 2 | |
7a6dbc2f | 3 | Copyright (C) 1991, 2004-2006, 2009-2018 Free Software Foundation, Inc. |
6ec2e0f5 SDJ |
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 | |
7a6dbc2f | 16 | along with this program. If not, see <https://www.gnu.org/licenses/>. |
6ec2e0f5 SDJ |
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 | } |