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/* POSIX compatible signal blocking for threads.
Copyright (C) 2011-2021 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include <signal.h>
#include <errno.h>
#include <stddef.h>
#if PTHREAD_SIGMASK_INEFFECTIVE
# include <string.h>
#endif
#if PTHREAD_SIGMASK_UNBLOCK_BUG
# include <unistd.h>
#endif
int
pthread_sigmask (int how, const sigset_t *new_mask, sigset_t *old_mask)
#undef pthread_sigmask
{
#if HAVE_PTHREAD_SIGMASK
int ret;
# if PTHREAD_SIGMASK_INEFFECTIVE
sigset_t omask, omask_copy;
sigset_t *old_mask_ptr = &omask;
sigemptyset (&omask);
/* Add a signal unlikely to be blocked, so that OMASK_COPY
is unlikely to match the actual mask. */
sigaddset (&omask, SIGILL);
memcpy (&omask_copy, &omask, sizeof omask);
# else
sigset_t *old_mask_ptr = old_mask;
# endif
ret = pthread_sigmask (how, new_mask, old_mask_ptr);
# if PTHREAD_SIGMASK_INEFFECTIVE
if (ret == 0)
{
/* Detect whether pthread_sigmask is currently ineffective.
Don't cache the information: libpthread.so could be dynamically
loaded after the program started and after pthread_sigmask was
called for the first time. */
if (memcmp (&omask_copy, &omask, sizeof omask) == 0
&& pthread_sigmask (1729, &omask_copy, NULL) == 0)
{
/* pthread_sigmask is currently ineffective. The program is not
linked to -lpthread. So use sigprocmask instead. */
return (sigprocmask (how, new_mask, old_mask) < 0 ? errno : 0);
}
if (old_mask)
memcpy (old_mask, &omask, sizeof omask);
}
# endif
# if PTHREAD_SIGMASK_FAILS_WITH_ERRNO
if (ret == -1)
return errno;
# endif
# if PTHREAD_SIGMASK_UNBLOCK_BUG
if (ret == 0
&& new_mask != NULL
&& (how == SIG_UNBLOCK || how == SIG_SETMASK))
{
/* Give the OS the opportunity to raise signals that were pending before
the pthread_sigmask call and have now been unblocked. */
usleep (1);
}
# endif
return ret;
#else
int ret = sigprocmask (how, new_mask, old_mask);
return (ret < 0 ? errno : 0);
#endif
}
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