mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-03 10:21:05 +00:00
94 lines
2.6 KiB
C
94 lines
2.6 KiB
C
/* sem_wait -- wait on a semaphore. Generic futex-using version.
|
|
Copyright (C) 2003-2016 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library 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
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#include <lowlevellock.h> /* lll_futex* used by the old code. */
|
|
#include "sem_waitcommon.c"
|
|
|
|
int
|
|
__new_sem_wait (sem_t *sem)
|
|
{
|
|
if (__new_sem_wait_fast ((struct new_sem *) sem, 0) == 0)
|
|
return 0;
|
|
else
|
|
return __new_sem_wait_slow((struct new_sem *) sem, NULL);
|
|
}
|
|
versioned_symbol (libpthread, __new_sem_wait, sem_wait, GLIBC_2_1);
|
|
|
|
#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
|
|
int
|
|
attribute_compat_text_section
|
|
__old_sem_wait (sem_t *sem)
|
|
{
|
|
int *futex = (int *) sem;
|
|
int err;
|
|
|
|
do
|
|
{
|
|
if (atomic_decrement_if_positive (futex) > 0)
|
|
return 0;
|
|
|
|
/* Enable asynchronous cancellation. Required by the standard. */
|
|
int oldtype = __pthread_enable_asynccancel ();
|
|
|
|
/* Always assume the semaphore is shared. */
|
|
err = lll_futex_wait (futex, 0, LLL_SHARED);
|
|
|
|
/* Disable asynchronous cancellation. */
|
|
__pthread_disable_asynccancel (oldtype);
|
|
}
|
|
while (err == 0 || err == -EWOULDBLOCK);
|
|
|
|
__set_errno (-err);
|
|
return -1;
|
|
}
|
|
|
|
compat_symbol (libpthread, __old_sem_wait, sem_wait, GLIBC_2_0);
|
|
#endif
|
|
|
|
int
|
|
__new_sem_trywait (sem_t *sem)
|
|
{
|
|
/* We must not fail spuriously, so require a definitive result even if this
|
|
may lead to a long execution time. */
|
|
if (__new_sem_wait_fast ((struct new_sem *) sem, 1) == 0)
|
|
return 0;
|
|
__set_errno (EAGAIN);
|
|
return -1;
|
|
}
|
|
versioned_symbol (libpthread, __new_sem_trywait, sem_trywait, GLIBC_2_1);
|
|
#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
|
|
int
|
|
__old_sem_trywait (sem_t *sem)
|
|
{
|
|
int *futex = (int *) sem;
|
|
int val;
|
|
|
|
if (*futex > 0)
|
|
{
|
|
val = atomic_decrement_if_positive (futex);
|
|
if (val > 0)
|
|
return 0;
|
|
}
|
|
|
|
__set_errno (EAGAIN);
|
|
return -1;
|
|
}
|
|
compat_symbol (libpthread, __old_sem_trywait, sem_trywait, GLIBC_2_0);
|
|
#endif
|