1 files changed, 140 insertions, 0 deletions
diff --git a/nuttx/sched/sem_close.c b/nuttx/sched/sem_close.c
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+/****************************************************************************
+ * sched/sem_close.c
+ *
+ *   Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <errno.h>
+#include <semaphore.h>
+#include <sched.h>
+
+#include "os_internal.h"
+#include "sem_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name:  sem_close
+ *
+ * Description:
+ *   This function is called to indicate that the calling task is finished
+ *   with the specified named semaphore, 'sem'.  The sem_close() deallocates
+ *   any system resources allocated by the system for this named semaphore.
+ *
+ *   If the semaphore has not been removed with a call to sem_unlink(), then
+ *   sem_close() has no effect on the named semaphore.  However, when the
+ *   named semaphore has been fully unlinked, the semaphore will vanish when
+ *   the last task closes it.
+ *
+ * Parameters:
+ *  sem - semaphore descriptor
+ *
+ * Return Value:
+ *  0 (OK), or -1 (ERROR) if unsuccessful.
+ *
+ * Assumptions:
+ *   - Care must be taken to avoid risking the deletion of a semaphore that
+ *     another calling task has already locked.
+ *   - sem_close must not be called for an un-named semaphore
+ *
+ ****************************************************************************/
+
+int sem_close(FAR sem_t *sem)
+{
+  FAR nsem_t *psem;
+  int ret = ERROR;
+
+  /* Verify the inputs */
+
+  if (sem)
+    {
+      sched_lock();
+
+      /* Search the list of named semaphores */
+
+      for (psem = (FAR nsem_t*)g_nsems.head;
+           ((psem) && (sem != &psem->sem));
+           psem = psem->flink);
+
+      /* Check if we found it */
+
+      if (psem)
+        {
+          /* Decrement the count of sem_open connections to this semaphore */
+
+          if (psem->nconnect) psem->nconnect--;
+
+          /* If the semaphore is no long connected to any processes AND the
+           * semaphore was previously unlinked, then deallocate it.
+           */
+
+          if (!psem->nconnect && psem->unlinked)
+            {
+              dq_rem((FAR dq_entry_t*)psem, &g_nsems);
+              sched_free(psem);
+            }
+          ret = OK;
+        }
+
+      sched_unlock();
+    }
+
+  return ret;
+}