1 /* POSIX compatible signal blocking for threads.
2 Copyright (C) 2011-2023 Free Software Foundation, Inc.
3
4 This file is free software: you can redistribute it and/or modify
5 it under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
8
9 This file is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
16
17 #include <config.h>
18
19 /* Specification. */
20 #include <signal.h>
21
22 #include <errno.h>
23 #include <stddef.h>
24
25 #if PTHREAD_SIGMASK_INEFFECTIVE
26 # include <string.h>
27 #endif
28
29 #if PTHREAD_SIGMASK_UNBLOCK_BUG
30 # include <unistd.h>
31 #endif
32
33 int
34 pthread_sigmask (int how, const sigset_t *new_mask, sigset_t *old_mask)
35 #undef pthread_sigmask
36 {
37 #if HAVE_PTHREAD_SIGMASK
38 int ret;
39
40 # if PTHREAD_SIGMASK_INEFFECTIVE
41 sigset_t omask, omask_copy;
42 sigset_t *old_mask_ptr = &omask;
43 sigemptyset (&omask);
44 /* Add a signal unlikely to be blocked, so that OMASK_COPY
45 is unlikely to match the actual mask. */
46 sigaddset (&omask, SIGILL);
47 memcpy (&omask_copy, &omask, sizeof omask);
48 # else
49 sigset_t *old_mask_ptr = old_mask;
50 # endif
51
52 ret = pthread_sigmask (how, new_mask, old_mask_ptr);
53
54 # if PTHREAD_SIGMASK_INEFFECTIVE
55 if (ret == 0)
56 {
57 /* Detect whether pthread_sigmask is currently ineffective.
58 Don't cache the information: libpthread.so could be dynamically
59 loaded after the program started and after pthread_sigmask was
60 called for the first time. */
61 if (memcmp (&omask_copy, &omask, sizeof omask) == 0
62 && pthread_sigmask (1729, &omask_copy, NULL) == 0)
63 {
64 /* pthread_sigmask is currently ineffective. The program is not
65 linked to -lpthread. So use sigprocmask instead. */
66 return (sigprocmask (how, new_mask, old_mask) < 0 ? errno : 0);
67 }
68
69 if (old_mask)
70 memcpy (old_mask, &omask, sizeof omask);
71 }
72 # endif
73 # if PTHREAD_SIGMASK_FAILS_WITH_ERRNO
74 if (ret == -1)
75 return errno;
76 # endif
77 # if PTHREAD_SIGMASK_UNBLOCK_BUG
78 if (ret == 0
79 && new_mask != NULL
80 && (how == SIG_UNBLOCK || how == SIG_SETMASK))
81 {
82 /* Give the OS the opportunity to raise signals that were pending before
83 the pthread_sigmask call and have now been unblocked. */
84 usleep (1);
85 }
86 # endif
87 return ret;
88 #else
89 int ret = sigprocmask (how, new_mask, old_mask);
90 return (ret < 0 ? errno : 0);
91 #endif
92 }