2007-11-20 Neal H. Walfield <neal@gnu.org>

	Also merge semaphore changes from mainline Hurd.

1 files changed, 42 insertions, 0 deletions

diff --git a/libpthread/sysdeps/generic/sem-trywait.c b/libpthread/sysdeps/generic/sem-trywait.c
new file mode 100644
index 0000000..199f317
--- /dev/null
+++ b/libpthread/sysdeps/generic/sem-trywait.c
@@ -0,0 +1,42 @@
+/* Lock a semaphore if it does not require blocking.  Generic version.
+   Copyright (C) 2005 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <semaphore.h>
+#include <errno.h>
+
+#include <pt-internal.h>
+
+int
+__sem_trywait (sem_t *sem)
+{
+  __pthread_spin_lock (&sem->__lock);
+  if (sem->__value > 0)
+    /* Successful down.  */
+    {
+      sem->__value --;
+      __pthread_spin_unlock (&sem->__lock);
+      return 0;
+    }
+  __pthread_spin_unlock (&sem->__lock);
+
+  errno = EAGAIN;
+  return -1;
+}
+
+strong_alias (__sem_trywait, sem_trywait);