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+/*
+ * -------------------------------------------------------------
+ *
+ * Module: sem_destroy.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-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 current list of contributors is contained
+ * in the file CONTRIBUTORS 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 "pthread.h"
+#include "semaphore.h"
+#include "implement.h"
+
+
+int
+sem_destroy (sem_t * sem)
+ /*
+ * ------------------------------------------------------
+ * DOCPUBLIC
+ * This function destroys an unnamed semaphore.
+ *
+ * PARAMETERS
+ * sem
+ * pointer to an instance of sem_t
+ *
+ * DESCRIPTION
+ * This function destroys an unnamed semaphore.
+ *
+ * RESULTS
+ * 0 successfully destroyed semaphore,
+ * -1 failed, error in errno
+ * ERRNO
+ * EINVAL 'sem' is not a valid semaphore,
+ * ENOSYS semaphores are not supported,
+ * EBUSY threads (or processes) are currently
+ * blocked on 'sem'
+ *
+ * ------------------------------------------------------
+ */
+{
+ int result = 0;
+ sem_t s = NULL;
+
+ if (sem == NULL || *sem == NULL)
+ {
+ result = EINVAL;
+ }
+ else
+ {
+ s = *sem;
+
+ if ((result = pthread_mutex_lock (&s->lock)) == 0)
+ {
+ if (s->value < 0)
+ {
+ (void) pthread_mutex_unlock (&s->lock);
+ result = EBUSY;
+ }
+ else
+ {
+ /* There are no threads currently blocked on this semaphore. */
+
+ if (!CloseHandle (s->sem))
+ {
+ (void) pthread_mutex_unlock (&s->lock);
+ result = EINVAL;
+ }
+ else
+ {
+ /*
+ * Invalidate the semaphore handle when we have the lock.
+ * Other sema operations should test this after acquiring the lock
+ * to check that the sema is still valid, i.e. before performing any
+ * operations. This may only be necessary before the sema op routine
+ * returns so that the routine can return EINVAL - e.g. if setting
+ * s->value to SEM_VALUE_MAX below does force a fall-through.
+ */
+ *sem = NULL;
+
+ /* Prevent anyone else actually waiting on or posting this sema.
+ */
+ s->value = SEM_VALUE_MAX;
+
+ (void) pthread_mutex_unlock (&s->lock);
+
+ do
+ {
+ /* Give other threads a chance to run and exit any sema op
+ * routines. Due to the SEM_VALUE_MAX value, if sem_post or
+ * sem_wait were blocked by us they should fall through.
+ */
+ Sleep(0);
+ }
+ while (pthread_mutex_destroy (&s->lock) == EBUSY);
+ }
+ }
+ }
+ }
+
+ if (result != 0)
+ {
+ errno = result;
+ return -1;
+ }
+
+ free (s);
+
+ return 0;
+
+} /* sem_destroy */