1 files changed, 117 insertions, 0 deletions
diff --git a/pthreads/sem_trywait.c b/pthreads/sem_trywait.c
new file mode 100644
index 000000000..63614ba2b
--- /dev/null
+++ b/pthreads/sem_trywait.c
@@ -0,0 +1,117 @@
+/*
+ * -------------------------------------------------------------
+ *
+ * Module: sem_trywait.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_trywait (sem_t * sem)
+     /*
+      * ------------------------------------------------------
+      * DOCPUBLIC
+      *      This function tries to wait on a semaphore.
+      *
+      * PARAMETERS
+      *      sem
+      *              pointer to an instance of sem_t
+      *
+      * DESCRIPTION
+      *      This function tries to wait on a semaphore. If the
+      *      semaphore value is greater than zero, it decreases
+      *      its value by one. If the semaphore value is zero, then
+      *      this function returns immediately with the error EAGAIN
+      *
+      * RESULTS
+      *              0               successfully decreased semaphore,
+      *              -1              failed, error in errno
+      * ERRNO
+      *              EAGAIN          the semaphore was already locked,
+      *              EINVAL          'sem' is not a valid semaphore,
+      *              ENOTSUP         sem_trywait is not supported,
+      *              EINTR           the function was interrupted by a signal,
+      *              EDEADLK         a deadlock condition was detected.
+      *
+      * ------------------------------------------------------
+      */
+{
+  int result = 0;
+  sem_t s = *sem;
+
+  if (s == NULL)
+    {
+      result = EINVAL;
+    }
+  else if ((result = pthread_mutex_lock (&s->lock)) == 0)
+    {
+      /* See sem_destroy.c
+       */
+     if (*sem == NULL)
+        {
+          (void) pthread_mutex_unlock (&s->lock);
+          errno = EINVAL;
+          return -1;
+        }
+
+      if (s->value > 0)
+	{
+	  s->value--;
+	}
+      else
+	{
+	  result = EAGAIN;
+	}
+
+      (void) pthread_mutex_unlock (&s->lock);
+    }
+
+  if (result != 0)
+    {
+      errno = result;
+      return -1;
+    }
+
+  return 0;
+
+}				/* sem_trywait */