text: /*
   * -------------------------------------------------------------
   *
   * Module: sem_timedwait.c
   *
   * Purpose:
   *	Semaphores aren't actually part of the PThreads standard.
   *	They are defined by the POSIX Standard:
   *
   *		POSIX 1003.1b-1993	(POSIX.1b)
   *
   * -------------------------------------------------------------
   *
   * --------------------------------------------------------------------------
   *
   *      Pthreads-embedded (PTE) - POSIX Threads Library for embedded systems
   *      Copyright(C) 2008 Jason Schmidlapp
   *
   *      Contact Email: jschmidlapp@users.sourceforge.net
   *
   *
   *      Based upon Pthreads-win32 - POSIX Threads Library for Win32
   *      Copyright(C) 1998 John E. Bossom
   *      Copyright(C) 1999,2005 Pthreads-win32 contributors
   *
   *      Contact Email: rpj@callisto.canberra.edu.au
   *
   *      The original list of contributors to the Pthreads-win32 project
   *      is contained in the file CONTRIBUTORS.ptw32 included with the
   *      source code distribution. The list can also be seen at the
   *      following World Wide Web location:
   *      http://sources.redhat.com/pthreads-win32/contributors.html
   *
   *      This 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 of the License, or (at your option) any later version.
   *
   *      This 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 this library in the file COPYING.LIB;
   *      if not, write to the Free Software Foundation, Inc.,
   *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
   */
  
  #include <stdio.h>
  #include <stdlib.h>
  
  #include "pthread.h"
  #include "semaphore.h"
  #include "implement.h"
  
  typedef struct
    {
      sem_t sem;
      int * resultPtr;
    } sem_timedwait_cleanup_args_t;
  
  static void
  pte_sem_timedwait_cleanup (void * args)
  {
    sem_timedwait_cleanup_args_t * a = (sem_timedwait_cleanup_args_t *)args;
    sem_t s = a->sem;
  
    if (pthread_mutex_lock (&s->lock) == 0)
      {
        /*
         * We either timed out or were cancelled.
         * If someone has posted between then and now we try to take the semaphore.
         * Otherwise the semaphore count may be wrong after we
         * return. In the case of a cancellation, it is as if we
         * were cancelled just before we return (after taking the semaphore)
         * which is ok.
         */
        unsigned int timeout = 0;
        if (pte_osSemaphorePend(s->sem, &timeout) == PTE_OS_OK)
          {
            /* We got the semaphore on the second attempt */
            *(a->resultPtr) = 0;
          }
        else
          {
            /* Indicate we're no longer waiting */
            s->value++;
  
            /*
             * Don't release the OS sema, it doesn't need adjustment
             * because it doesn't record the number of waiters.
             */
  
          }
        (void) pthread_mutex_unlock (&s->lock);
      }
  }
  
  
  int
  sem_timedwait (sem_t * sem, const struct timespec *abstime)
  /*
   * ------------------------------------------------------
   * DOCPUBLIC
   *      This function waits on a semaphore possibly until
   *      'abstime' time.
   *
   * PARAMETERS
   *      sem
   *              pointer to an instance of sem_t
   *
   *      abstime
   *              pointer to an instance of struct timespec
   *
   * DESCRIPTION
   *      This function waits on a semaphore. If the
   *      semaphore value is greater than zero, it decreases
   *      its value by one. If the semaphore value is zero, then
   *      the calling thread (or process) is blocked until it can
   *      successfully decrease the value or until interrupted by
   *      a signal.
   *
   *      If 'abstime' is a NULL pointer then this function will
   *      block until it can successfully decrease the value or
   *      until interrupted by a signal.
   *
   * RESULTS
   *              0               successfully decreased semaphore,
   *              -1              failed, error in errno
   * ERRNO
   *              EINVAL          'sem' is not a valid semaphore,
   *              ENOSYS          semaphores are not supported,
   *              EINTR           the function was interrupted by a signal,
   *              EDEADLK         a deadlock condition was detected.
   *              ETIMEDOUT       abstime elapsed before success.
   *
   * ------------------------------------------------------
   */
  {
    int result = 0;
    sem_t s = *sem;
  
  
    pthread_testcancel();
  
    if (sem == NULL)
      {
        result = EINVAL;
      }
    else
      {
        unsigned int milliseconds;
        unsigned int *pTimeout;
  
        if (abstime == NULL)
          {
            pTimeout = NULL;
          }
        else
          {
            /*
             * Calculate timeout as milliseconds from current system time.
             */
            milliseconds = pte_relmillisecs (abstime);
            pTimeout = &milliseconds;
          }
  
        if ((result = pthread_mutex_lock (&s->lock)) == 0)
          {
            int v;
  
            /* See sem_destroy.c
             */
            if (*sem == NULL)
              {
                (void) pthread_mutex_unlock (&s->lock);
                errno = EINVAL;
                return -1;
              }
  
            v = --s->value;
            (void) pthread_mutex_unlock (&s->lock);
  
            if (v < 0)
              {
  
                {
                  sem_timedwait_cleanup_args_t cleanup_args;
  
                  cleanup_args.sem = s;
                  cleanup_args.resultPtr = &result;
  
                  /* Must wait */
                  pthread_cleanup_push(pte_sem_timedwait_cleanup, (void *) &cleanup_args);
  
                  result = pte_cancellable_wait(s->sem,pTimeout);
  
                  pthread_cleanup_pop(result);
                }
              }
          }
  
      }
  
    if (result != 0)
      {
  
        errno = result;
        return -1;
  
      }
  
    return 0;
  
  }				/* sem_timedwait */
  