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77 lines
2.1 KiB
C++
77 lines
2.1 KiB
C++
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/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2014.
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This file is part of Sortix libpthread.
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Sortix libpthread is free software: you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by the
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Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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Sortix libpthread is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with Sortix libpthread. If not, see <http://www.gnu.org/licenses/>.
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sem_timedwait.c++
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Lock a semaphore.
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*******************************************************************************/
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#include <errno.h>
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#include <sched.h>
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#include <semaphore.h>
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#include <signal.h>
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#include <stddef.h>
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#include <time.h>
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#include <timespec.h>
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extern "C"
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int sem_timedwait(sem_t* restrict sem, const struct timespec* restrict abstime)
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{
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if ( sem_trywait(sem) == 0 )
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return 0;
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if ( errno != EAGAIN )
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return -1;
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sigset_t old_set_mask;
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sigset_t old_set_allowed;
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sigset_t all_signals;
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sigfillset(&all_signals);
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sigprocmask(SIG_SETMASK, &all_signals, &old_set_mask);
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signotset(&old_set_allowed, &old_set_mask);
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while ( sem_trywait(sem) != 0 )
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{
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// TODO: Using CLOCK_REALTIME for this is bad as it is not monotonic. We
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// need to enchance the semaphore API so a better clock can be
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// used instead.
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if ( errno == EAGAIN )
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{
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struct timespec now;
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clock_gettime(CLOCK_REALTIME, &now);
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if ( timespec_le(*abstime, now) )
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errno = ETIMEDOUT;
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}
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if ( errno == EAGAIN && sigpending(&old_set_allowed) )
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errno = EINTR;
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if ( errno != EAGAIN )
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{
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sigprocmask(SIG_SETMASK, &old_set_mask, NULL);
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return -1;
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}
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sched_yield();
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}
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sigprocmask(SIG_SETMASK, &old_set_mask, NULL);
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return 0;
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}
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