| 1 | /* POSIX compatible signal blocking for threads.
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| 2 | Copyright (C) 2011-2021 Free Software Foundation, Inc.
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| 3 |
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| 4 | This file is free software: you can redistribute it and/or modify
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| 5 | it under the terms of the GNU Lesser General Public License as
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| 6 | published by the Free Software Foundation; either version 2.1 of the
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| 7 | License, or (at your option) any later version.
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| 8 |
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| 9 | This file is distributed in the hope that it will be useful,
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 12 | GNU Lesser General Public License for more details.
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| 13 |
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| 14 | You should have received a copy of the GNU Lesser General Public License
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| 15 | along with this program. If not, see <https://www.gnu.org/licenses/>. */
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| 16 |
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| 17 | #include <config.h>
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| 18 |
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| 19 | /* Specification. */
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| 20 | #include <signal.h>
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| 21 |
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| 22 | #include <errno.h>
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| 23 | #include <stddef.h>
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| 24 |
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| 25 | #if PTHREAD_SIGMASK_INEFFECTIVE
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| 26 | # include <string.h>
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| 27 | #endif
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| 28 |
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| 29 | #if PTHREAD_SIGMASK_UNBLOCK_BUG
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| 30 | # include <unistd.h>
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| 31 | #endif
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| 32 |
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| 33 | int
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| 34 | pthread_sigmask (int how, const sigset_t *new_mask, sigset_t *old_mask)
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| 35 | #undef pthread_sigmask
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| 36 | {
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| 37 | #if HAVE_PTHREAD_SIGMASK
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| 38 | int ret;
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| 39 |
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| 40 | # if PTHREAD_SIGMASK_INEFFECTIVE
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| 41 | sigset_t omask, omask_copy;
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| 42 | sigset_t *old_mask_ptr = &omask;
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| 43 | sigemptyset (&omask);
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| 44 | /* Add a signal unlikely to be blocked, so that OMASK_COPY
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| 45 | is unlikely to match the actual mask. */
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| 46 | sigaddset (&omask, SIGILL);
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| 47 | memcpy (&omask_copy, &omask, sizeof omask);
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| 48 | # else
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| 49 | sigset_t *old_mask_ptr = old_mask;
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| 50 | # endif
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| 51 |
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| 52 | ret = pthread_sigmask (how, new_mask, old_mask_ptr);
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| 53 |
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| 54 | # if PTHREAD_SIGMASK_INEFFECTIVE
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| 55 | if (ret == 0)
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| 56 | {
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| 57 | /* Detect whether pthread_sigmask is currently ineffective.
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| 58 | Don't cache the information: libpthread.so could be dynamically
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| 59 | loaded after the program started and after pthread_sigmask was
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| 60 | called for the first time. */
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| 61 | if (memcmp (&omask_copy, &omask, sizeof omask) == 0
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| 62 | && pthread_sigmask (1729, &omask_copy, NULL) == 0)
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| 63 | {
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| 64 | /* pthread_sigmask is currently ineffective. The program is not
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| 65 | linked to -lpthread. So use sigprocmask instead. */
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| 66 | return (sigprocmask (how, new_mask, old_mask) < 0 ? errno : 0);
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| 67 | }
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| 68 |
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| 69 | if (old_mask)
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| 70 | memcpy (old_mask, &omask, sizeof omask);
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| 71 | }
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| 72 | # endif
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| 73 | # if PTHREAD_SIGMASK_FAILS_WITH_ERRNO
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| 74 | if (ret == -1)
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| 75 | return errno;
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| 76 | # endif
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| 77 | # if PTHREAD_SIGMASK_UNBLOCK_BUG
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| 78 | if (ret == 0
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| 79 | && new_mask != NULL
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| 80 | && (how == SIG_UNBLOCK || how == SIG_SETMASK))
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| 81 | {
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| 82 | /* Give the OS the opportunity to raise signals that were pending before
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| 83 | the pthread_sigmask call and have now been unblocked. */
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| 84 | usleep (1);
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| 85 | }
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| 86 | # endif
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| 87 | return ret;
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| 88 | #else
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| 89 | int ret = sigprocmask (how, new_mask, old_mask);
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| 90 | return (ret < 0 ? errno : 0);
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| 91 | #endif
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| 92 | }
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