diff options
Diffstat (limited to 'nptl/sem_timedwait.c')
| -rw-r--r-- | nptl/sem_timedwait.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/nptl/sem_timedwait.c b/nptl/sem_timedwait.c new file mode 100644 index 0000000000..7dfe51dd8b --- /dev/null +++ b/nptl/sem_timedwait.c @@ -0,0 +1,116 @@ +/* sem_timedwait -- wait on a semaphore. Generic futex-using version. + Copyright (C) 2003-2014 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 <errno.h> +#include <sysdep.h> +#include <lowlevellock.h> +#include <internaltypes.h> +#include <semaphore.h> + +#include <pthreadP.h> +#include <shlib-compat.h> + + +extern void __sem_wait_cleanup (void *arg) attribute_hidden; + +/* This is in a seperate function in order to make sure gcc + puts the call site into an exception region, and thus the + cleanups get properly run. */ +static int +__attribute__ ((noinline)) +do_futex_timed_wait (struct new_sem *isem, struct timespec *rt) +{ + int err, oldtype = __pthread_enable_asynccancel (); + + err = lll_futex_timed_wait (&isem->value, 0, rt, + isem->private ^ FUTEX_PRIVATE_FLAG); + + __pthread_disable_asynccancel (oldtype); + return err; +} + +int +sem_timedwait (sem_t *sem, const struct timespec *abstime) +{ + struct new_sem *isem = (struct new_sem *) sem; + int err; + + if (atomic_decrement_if_positive (&isem->value) > 0) + return 0; + + if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000) + { + __set_errno (EINVAL); + return -1; + } + + atomic_increment (&isem->nwaiters); + + pthread_cleanup_push (__sem_wait_cleanup, isem); + + while (1) + { + struct timeval tv; + struct timespec rt; + int sec, nsec; + + /* Get the current time. */ + __gettimeofday (&tv, NULL); + + /* Compute relative timeout. */ + sec = abstime->tv_sec - tv.tv_sec; + nsec = abstime->tv_nsec - tv.tv_usec * 1000; + if (nsec < 0) + { + nsec += 1000000000; + --sec; + } + + /* Already timed out? */ + if (sec < 0) + { + __set_errno (ETIMEDOUT); + err = -1; + break; + } + + /* Do wait. */ + rt.tv_sec = sec; + rt.tv_nsec = nsec; + err = do_futex_timed_wait(isem, &rt); + if (err != 0 && err != -EWOULDBLOCK) + { + __set_errno (-err); + err = -1; + break; + } + + if (atomic_decrement_if_positive (&isem->value) > 0) + { + err = 0; + break; + } + } + + pthread_cleanup_pop (0); + + atomic_decrement (&isem->nwaiters); + + return err; +} |