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51 lines
1.5 KiB
C
51 lines
1.5 KiB
C
/* sem_trywait -- wait on a semaphore. Generic futex-using version.
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Copyright (C) 2003-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Paul Mackerras <paulus@au.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, see
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<http://www.gnu.org/licenses/>. */
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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 <internaltypes.h>
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#include <semaphore.h>
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#include <atomic.h>
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#include <shlib-compat.h>
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int
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__new_sem_trywait (sem_t *sem)
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{
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int *futex = (int *) sem;
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int val;
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if (*futex > 0)
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{
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val = atomic_decrement_if_positive (futex);
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if (val > 0)
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return 0;
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}
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__set_errno (EAGAIN);
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return -1;
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}
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versioned_symbol (libpthread, __new_sem_trywait, sem_trywait, GLIBC_2_1);
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#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
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strong_alias (__new_sem_trywait, __old_sem_trywait)
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compat_symbol (libpthread, __old_sem_trywait, sem_trywait, GLIBC_2_0);
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#endif
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