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1 files changed, 137 insertions, 0 deletions

diff --git a/nptl/sysdeps/pthread/pthread_rwlock_timedrdlock.c b/nptl/sysdeps/pthread/pthread_rwlock_timedrdlock.c
new file mode 100644
index 0000000000..80ea83a3dd
--- /dev/null
+++ b/nptl/sysdeps/pthread/pthread_rwlock_timedrdlock.c
@@ -0,0 +1,137 @@
+/* Copyright (C) 2003, 2004 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
+
+   The GNU C 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 2.1 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <errno.h>
+#include <sysdep.h>
+#include <lowlevellock.h>
+#include <pthread.h>
+#include <pthreadP.h>
+
+
+/* Try to acquire read lock for RWLOCK or return after specfied time.  */
+int
+pthread_rwlock_timedrdlock (rwlock, abstime)
+     pthread_rwlock_t *rwlock;
+     const struct timespec *abstime;
+{
+  int result = 0;
+
+  /* Make sure we are along.  */
+  lll_mutex_lock(rwlock->__data.__lock);
+
+  while (1)
+    {
+      int err;
+
+      /* Get the rwlock if there is no writer...  */
+      if (rwlock->__data.__writer == 0
+	  /* ...and if either no writer is waiting or we prefer readers.  */
+	  && (!rwlock->__data.__nr_writers_queued
+	      || rwlock->__data.__flags == 0))
+	{
+	  /* Increment the reader counter.  Avoid overflow.  */
+	  if (++rwlock->__data.__nr_readers == 0)
+	    {
+	      /* Overflow on number of readers.	 */
+	      --rwlock->__data.__nr_readers;
+	      result = EAGAIN;
+	    }
+
+	  break;
+	}
+
+      /* Make sure we are not holding the rwlock as a writer.  This is
+	 a deadlock situation we recognize and report.  */
+      if (__builtin_expect (rwlock->__data.__writer
+			    == THREAD_GETMEM (THREAD_SELF, tid), 0))
+	{
+	  result = EDEADLK;
+	  break;
+	}
+
+      /* Make sure the passed in timeout value is valid.  Ideally this
+	 test would be executed once.  But since it must not be
+	 performed if we would not block at all simply moving the test
+	 to the front is no option.  Replicating all the code is
+	 costly while this test is not.  */
+      if (__builtin_expect (abstime->tv_nsec >= 1000000000
+                            || abstime->tv_nsec < 0, 0))
+	{
+	  result = EINVAL;
+	  break;
+	}
+
+      /* Get the current time.  So far we support only one clock.  */
+      struct timeval tv;
+      (void) gettimeofday (&tv, NULL);
+
+      /* Convert the absolute timeout value to a relative timeout.  */
+      struct timespec rt;
+      rt.tv_sec = abstime->tv_sec - tv.tv_sec;
+      rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
+      if (rt.tv_nsec < 0)
+	{
+	  rt.tv_nsec += 1000000000;
+	  --rt.tv_sec;
+	}
+      /* Did we already time out?  */
+      if (rt.tv_sec < 0)
+	{
+	  /* Yep, return with an appropriate error.  */
+	  result = ETIMEDOUT;
+	  break;
+	}
+
+      /* Remember that we are a reader.  */
+      if (++rwlock->__data.__nr_readers_queued == 0)
+	{
+	  /* Overflow on number of queued readers.  */
+	  --rwlock->__data.__nr_readers_queued;
+	  result = EAGAIN;
+	  break;
+	}
+
+      int waitval = rwlock->__data.__readers_wakeup;
+
+      /* Free the lock.  */
+      lll_mutex_unlock (rwlock->__data.__lock);
+
+      /* Wait for the writer to finish.  */
+      err = lll_futex_timed_wait (&rwlock->__data.__readers_wakeup,
+				  waitval, &rt);
+
+      /* Get the lock.  */
+      lll_mutex_lock (rwlock->__data.__lock);
+
+      --rwlock->__data.__nr_readers_queued;
+
+      /* Did the futex call time out?  */
+      if (err == -ETIMEDOUT)
+	{
+	  /* Yep, report it.  */
+	  result = ETIMEDOUT;
+	  break;
+	}
+    }
+
+  /* We are done, free the lock.  */
+  lll_mutex_unlock (rwlock->__data.__lock);
+
+  return result;
+}