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644eff0c9f
2004-08-10 GOTO Masanori <gotom@debian.or.jp> * locale/C-time.c: Change default ERA value from NULL to "". * locale/tst-C-locale.c: Add test case for ERA keywords.
96 lines
2.8 KiB
C
96 lines
2.8 KiB
C
/* Copyright (C) 2003, 2004 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <errno.h>
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#include <sysdep.h>
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#include <lowlevellock.h>
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#include <pthread.h>
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#include <pthreadP.h>
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/* Acquire read lock for RWLOCK. */
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int
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__pthread_rwlock_rdlock (rwlock)
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pthread_rwlock_t *rwlock;
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{
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int result = 0;
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/* Make sure we are along. */
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lll_mutex_lock (rwlock->__data.__lock);
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while (1)
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{
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/* Get the rwlock if there is no writer... */
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if (rwlock->__data.__writer == 0
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/* ...and if either no writer is waiting or we prefer readers. */
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&& (!rwlock->__data.__nr_writers_queued
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|| rwlock->__data.__flags == 0))
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{
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/* Increment the reader counter. Avoid overflow. */
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if (__builtin_expect (++rwlock->__data.__nr_readers == 0, 0))
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{
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/* Overflow on number of readers. */
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--rwlock->__data.__nr_readers;
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result = EAGAIN;
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}
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break;
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}
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/* Make sure we are not holding the rwlock as a writer. This is
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a deadlock situation we recognize and report. */
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if (__builtin_expect (rwlock->__data.__writer
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== THREAD_GETMEM (THREAD_SELF, tid), 0))
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{
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result = EDEADLK;
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break;
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}
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/* Remember that we are a reader. */
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if (__builtin_expect (++rwlock->__data.__nr_readers_queued == 0, 0))
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{
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/* Overflow on number of queued readers. */
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--rwlock->__data.__nr_readers_queued;
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result = EAGAIN;
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break;
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}
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int waitval = rwlock->__data.__readers_wakeup;
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/* Free the lock. */
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lll_mutex_unlock (rwlock->__data.__lock);
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/* Wait for the writer to finish. */
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lll_futex_wait (&rwlock->__data.__readers_wakeup, waitval);
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/* Get the lock. */
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lll_mutex_lock (rwlock->__data.__lock);
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--rwlock->__data.__nr_readers_queued;
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}
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/* We are done, free the lock. */
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lll_mutex_unlock (rwlock->__data.__lock);
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return result;
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}
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weak_alias (__pthread_rwlock_rdlock, pthread_rwlock_rdlock)
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strong_alias (__pthread_rwlock_rdlock, __pthread_rwlock_rdlock_internal)
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