atexit() and on_exit() may now be configured to support multiple exit callbacks

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4995 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 67 insertions, 21 deletions

diff --git a/nuttx/sched/atexit.c b/nuttx/sched/atexit.c
index 2c9b89d92..f7d81bec2 100644
--- a/nuttx/sched/atexit.c
+++ b/nuttx/sched/atexit.c
@@ -1,4 +1,4 @@
-/************************************************************************
+/****************************************************************************
  * sched/atexit.c
  *
  *   Copyright (C) 2007, 2009, 2011-2012 Gregory Nutt. All rights reserved.
@@ -31,11 +31,11 @@
  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  *
- ************************************************************************/
+ ****************************************************************************/
 
-/************************************************************************
+/****************************************************************************
  * Included Files
- ************************************************************************/
+ ****************************************************************************/
 
 #include <nuttx/config.h>
 
@@ -51,50 +51,95 @@
 
 #ifdef CONFIG_SCHED_ATEXIT
 
-/************************************************************************
+/****************************************************************************
  * Pre-processor Definitions
- ************************************************************************/
+ ****************************************************************************/
 
-/************************************************************************
+/****************************************************************************
  * Private Type Declarations
- ************************************************************************/
+ ****************************************************************************/
 
-/************************************************************************
+/****************************************************************************
  * Global Variables
- ************************************************************************/
+ ****************************************************************************/
 
-/************************************************************************
+/****************************************************************************
  * Private Variables
- ************************************************************************/
+ ****************************************************************************/
 
-/************************************************************************
+/****************************************************************************
  * Private Function Prototypes
- ************************************************************************/
+ ****************************************************************************/
 
-/************************************************************************
+/****************************************************************************
  * Private Functions
- ************************************************************************/
+ ****************************************************************************/
 
-/************************************************************************
+/****************************************************************************
  * Public Functions
- ************************************************************************/
+ ****************************************************************************/
 
-/************************************************************************
+/****************************************************************************
  * Name: atexit
  *
  * Description:
  *    Registers a function to be called at program exit.
+ *    The atexit() function registers the given function to be called
+ *    at normal process termination, whether via exit or via return from
+ *    the program's main().
+ *
+ *    NOTE: CONFIG_SCHED_ATEXIT must be defined to enable this function
+ *
+ *    Limitiations in the current implementation:
+ *
+ *      1. Only a single atexit function can be registered unless
+ *         CONFIG_SCHED_ATEXIT_MAX defines a larger number.
+ *      2. atexit functions are not inherited when a new task is
+ *         created.
  *
  * Parameters:
- *   func
+ *   func - A pointer to the function to be called when the task exits.
  *
  * Return Value:
  *   Zero on success. Non-zero on failure.
  *
- ************************************************************************/
+ ****************************************************************************/
 
 int atexit(void (*func)(void))
 {
+#if defined(CONFIG_SCHED_ATEXIT_MAX) && CONFIG_SCHED_ATEXIT_MAX > 1
+  _TCB *tcb = (_TCB*)g_readytorun.head;
+  int   index;
+  int   ret = ERROR;
+
+  /* The following must be atomic */
+
+  if (func)
+    {
+      sched_lock();
+
+      /* Search for the first available slot.  atexit() functions are registered
+       * from lower to higher arry indices; they must be called in the reverse
+       * order of registration when task exists, i.e., from higher to lower
+       * indices.
+       */
+
+      available = -1;
+      for (index = 0; index < CONFIG_SCHED_ATEXIT_MAX; index++)
+        {
+          if (!tcb->atexitfunc[index])
+            {
+              tcb->atexitfunc[index] = func;
+              ret = OK;
+              break;
+            }
+        }
+  
+      sched_unlock();
+    }
+
+  return ret;
+#else
   _TCB *tcb = (_TCB*)g_readytorun.head;
   int   ret = ERROR;
 
@@ -109,6 +154,7 @@ int atexit(void (*func)(void))
 
   sched_unlock();
   return ret;
+#endif
 }
 
 #endif /* CONFIG_SCHED_ATEXIT */