nptl/sysdeps/unix/sysv/linux/sem_timedwait.c

   1 /* sem_timedwait -- wait on a semaphore.  Generic futex-using version.
   2    Copyright (C) 2003, 2007 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <errno.h>
  22 #include <sysdep.h>
  23 #include <lowlevellock.h>
  24 #include <internaltypes.h>
  25 #include <semaphore.h>
  26
  27 #include <pthreadP.h>
  28 #include <shlib-compat.h>
  29
  30
  31 extern void __sem_wait_cleanup (void *arg) attribute_hidden;
  32
  33
  34 int
  35 sem_timedwait (sem_t *sem, const struct timespec *abstime)
  36 {
  37   struct new_sem *isem = (struct new_sem *) sem;
  38   int err;
  39
  40   if (atomic_decrement_if_positive (&isem->value) > 0)
  41     return 0;
  42
  43   if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
  44     {
  45       __set_errno (EINVAL);
  46       return -1;
  47     }
  48
  49   atomic_increment (&isem->nwaiters);
  50
  51   pthread_cleanup_push (__sem_wait_cleanup, isem);
  52
  53   while (1)
  54     {
  55       struct timeval tv;
  56       struct timespec rt;
  57       int sec, nsec;
  58
  59       /* Get the current time.  */
  60       __gettimeofday (&tv, NULL);
  61
  62       /* Compute relative timeout.  */
  63       sec = abstime->tv_sec - tv.tv_sec;
  64       nsec = abstime->tv_nsec - tv.tv_usec * 1000;
  65       if (nsec < 0)
  66         {
  67           nsec += 1000000000;
  68           --sec;
  69         }
  70
  71       /* Already timed out?  */
  72       err = -ETIMEDOUT;
  73       if (sec < 0)
  74         {
  75           __set_errno (ETIMEDOUT);
  76           err = -1;
  77           break;
  78         }
  79
  80       /* Do wait.  */
  81       rt.tv_sec = sec;
  82       rt.tv_nsec = nsec;
  83
  84       /* Enable asynchronous cancellation.  Required by the standard.  */
  85       int oldtype = __pthread_enable_asynccancel ();
  86
  87       err = lll_futex_timed_wait (&isem->value, 0, &rt,
  88                                   isem->private ^ FUTEX_PRIVATE_FLAG);
  89
  90       /* Disable asynchronous cancellation.  */
  91       __pthread_disable_asynccancel (oldtype);
  92
  93       if (err != 0 && err != -EWOULDBLOCK)
  94         {
  95           __set_errno (-err);
  96           err = -1;
  97           break;
  98         }
  99
 100       if (atomic_decrement_if_positive (&isem->value) > 0)
 101         {
 102           err = 0;
 103           break;
 104         }
 105     }
 106
 107   pthread_cleanup_pop (0);
 108
 109   atomic_decrement (&isem->nwaiters);
 110
 111   return err;
 112 }