rbtree: Update maximum node in LIFO order

The test sptests/sp35 showed a NULL pointer access due to an invalid
maximum node field (e.g. a tree with one element and NULL as the maximum
node).

4 files changed, 118 insertions, 18 deletions

diff --git a/cpukit/score/include/rtems/score/rbtree.h b/cpukit/score/include/rtems/score/rbtree.h
index b3f2ed4c0d..2ec77ead4f 100644
--- a/cpukit/score/include/rtems/score/rbtree.h
+++ b/cpukit/score/include/rtems/score/rbtree.h
@@ -219,15 +219,16 @@ RBTree_Node *_RBTree_Find(
 );
 
 /**
- *  @brief Insert @a the_node on the Red-Black Tree @a the_rbtree.
+ * @brief Inserts the node into the red-black tree.
  *
- *  This routine inserts @a the_node on the Red-Black Tree @a the_rbtree.
+ * In case the node is already a node of a tree, then this function yields
+ * unpredictable results.
  *
  * @param[in] the_rbtree The red-black tree control.
  * @param[in] the_node The node to insert.
  * @param[in] compare The node compare function.
  * @param[in] is_unique If true, then reject nodes with a duplicate key, else
- *   otherwise.
+ *   insert nodes in FIFO order in case the key value is equal to existing nodes.
  *
  * @retval NULL Successfully inserted.
  * @retval existing_node This is a unique insert and there exists a node with
@@ -487,19 +488,20 @@ RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Successor(
 }
 
 /**
- * @brief Gets a node with an extremal key value.
+ * @brief Gets a node with an extremal key value from the red-black tree.
  *
  * This function extracts a node with the minimum or maximum key value from
  * tree and returns a pointer to that node if it exists.  In case multiple
- * nodes with an extremal key value exist, then they are extracted in FIFO
- * order.
+ * nodes with a minimum key value exist, then they are extracted in FIFO order.
+ * In case multiple nodes with a maximum key value exist, then they are
+ * extracted in LIFO order.
  *
  * @param[in] the_rbtree The red-black tree control.
  * @param[in] dir Specifies whether to get a node with the minimum (RBT_LEFT)
  *   or maximum (RBT_RIGHT) key value.
  *
  * @retval NULL The tree is empty.
- * @retval extremal_node A node with the minimal or maximal key value on the
+ * @retval extremal_node A node with a minimal or maximal key value on the
  *   tree.
  */
 RTEMS_INLINE_ROUTINE RBTree_Node *_RBTree_Get(
diff --git a/cpukit/score/src/rbtreeinsert.c b/cpukit/score/src/rbtreeinsert.c
index b31c8e7bb7..afff1ef5f9 100644
--- a/cpukit/score/src/rbtreeinsert.c
+++ b/cpukit/score/src/rbtreeinsert.c
@@ -96,8 +96,8 @@ RBTree_Node *_RBTree_Insert(
         );
 
         if (
-          ( !dir && _RBTree_Is_lesser( compare_result ) )
-            || ( dir && _RBTree_Is_greater( compare_result ) )
+          ( dir == RBT_LEFT && _RBTree_Is_lesser( compare_result ) )
+            || ( dir == RBT_RIGHT && !_RBTree_Is_lesser( compare_result ) )
         ) {
           the_rbtree->first[ dir ] = the_node;
         }
diff --git a/testsuites/sptests/sprbtree01/init.c b/testsuites/sptests/sprbtree01/init.c
index 956271b325..2c62d12b6d 100644
--- a/testsuites/sptests/sprbtree01/init.c
+++ b/testsuites/sptests/sprbtree01/init.c
@@ -19,11 +19,13 @@ const char rtems_test_name[] = "SPRBTREE 1";
 /* forward declarations to avoid warnings */
 rtems_task Init(rtems_task_argument argument);
 
-int numbers[20] = {
-52, 99, 0, 85, 43, 44, 10, 60, 50, 19, 8, 68, 48, 57, 17, 67, 90, 12, 77, 71};
+static const int numbers[20] = {
+  52, 99, 0, 85, 43, 44, 10, 60, 50, 19, 8, 68, 48, 57, 17, 67, 90, 12, 77, 71
+};
 
-int numbers_sorted[20] = {
-  0, 8, 10, 12, 17, 19, 43, 44, 48, 50, 52, 57, 60, 67, 68, 71, 77, 85, 90, 99};
+static const int numbers_sorted[20] = {
+  0, 8, 10, 12, 17, 19, 43, 44, 48, 50, 52, 57, 60, 67, 68, 71, 77, 85, 90, 99
+};
 
 typedef struct {
   int              id;
@@ -121,11 +123,104 @@ static int rb_assert ( rtems_rbtree_node *root )
   }
 }
 
+static test_node some_nodes[] = {
+  { .key = 1 },
+  { .key = 1 },
+  { .key = 1 },
+  { .key = 2 },
+  { .key = 2 },
+  { .key = 2 }
+};
+
+static void min_max_insert(
+  rtems_rbtree_control *tree,
+  rtems_rbtree_node    *node,
+  rtems_rbtree_node    *min,
+  rtems_rbtree_node    *max
+)
+{
+  rb_insert_multi( tree, node );
+  rtems_test_assert( rb_assert( tree->root ) != -1 );
+  rtems_test_assert( tree->first[ 0 ] == min );
+  rtems_test_assert( tree->first[ 1 ] == max );
+}
+
+static void min_max_extract(
+  rtems_rbtree_control *tree,
+  rtems_rbtree_node    *node,
+  rtems_rbtree_node    *min,
+  rtems_rbtree_node    *max
+)
+{
+  rtems_rbtree_extract( tree, node );
+  rtems_test_assert( rb_assert( tree->root ) != -1 );
+  rtems_test_assert( tree->first[ 0 ] == min );
+  rtems_test_assert( tree->first[ 1 ] == max );
+}
+
+static void test_rbtree_min_max(void)
+{
+  rtems_rbtree_control  tree;
+  rtems_rbtree_node    *node;
+  rtems_rbtree_node    *min;
+  rtems_rbtree_node    *max;
+
+  puts( "INIT - Verify min/max node updates" );
+
+  rtems_rbtree_initialize_empty( &tree );
+  rtems_test_assert( rb_assert( tree.root ) == 1 );
+
+  node = &some_nodes[ 0 ].Node;
+  min = node;
+  max = node;
+  min_max_insert( &tree, node, min, max );
 
+  node = &some_nodes[ 1 ].Node;
+  max = node;
+  min_max_insert( &tree, node, min, max );
 
-rtems_task Init(
-    rtems_task_argument ignored
-    )
+  node = &some_nodes[ 2 ].Node;
+  max = node;
+  min_max_insert( &tree, node, min, max );
+
+  node = &some_nodes[ 3 ].Node;
+  max = node;
+  min_max_insert( &tree, node, min, max );
+
+  node = &some_nodes[ 4 ].Node;
+  max = node;
+  min_max_insert( &tree, node, min, max );
+
+  node = &some_nodes[ 5 ].Node;
+  max = node;
+  min_max_insert( &tree, node, min, max );
+
+  node = &some_nodes[ 1 ].Node;
+  min_max_extract( &tree, node, min, max );
+
+  node = &some_nodes[ 4 ].Node;
+  min_max_extract( &tree, node, min, max );
+
+  node = &some_nodes[ 0 ].Node;
+  min = &some_nodes[ 2 ].Node;
+  min_max_extract( &tree, node, min, max );
+
+  node = &some_nodes[ 5 ].Node;
+  max = &some_nodes[ 3 ].Node;
+  min_max_extract( &tree, node, min, max );
+
+  node = &some_nodes[ 2 ].Node;
+  min = &some_nodes[ 3 ].Node;
+  min_max_extract( &tree, node, min, max );
+
+  node = &some_nodes[ 3 ].Node;
+  min = NULL;
+  max = NULL;
+  min_max_extract( &tree, node, min, max );
+  rtems_test_assert( rtems_rbtree_is_empty( &tree ) );
+}
+
+rtems_task Init( rtems_task_argument ignored )
 {
   rtems_rbtree_control  rbtree1;
   rtems_rbtree_node    *p;
@@ -682,6 +777,8 @@ rtems_task Init(
     rtems_test_exit(0);
   }
 
+  test_rbtree_min_max();
+
   TEST_END();
   rtems_test_exit(0);
 }
diff --git a/testsuites/sptests/sprbtree01/sprbtree01.scn b/testsuites/sptests/sprbtree01/sprbtree01.scn
index 0bf200717b..0d37566770 100644
--- a/testsuites/sptests/sprbtree01/sprbtree01.scn
+++ b/testsuites/sptests/sprbtree01/sprbtree01.scn
@@ -1,4 +1,4 @@
-*** TEST OF RTEMS RBTREE API ***
+*** BEGIN OF TEST SPRBTREE 1 ***
 Init - Initialize rbtree empty
 INIT - Verify rtems_rbtree_insert with two nodes
 INIT - Verify rtems_rbtree_insert with the same value twice
@@ -31,4 +31,5 @@ INIT - Removing 100 nodes
 INIT - Verify rtems_rbtree_insert with 100 nodes value [99,0]
 INIT - Verify rtems_rbtree_find in a duplicate tree
 INIT - Removing 100 nodes
-*** END OF RTEMS RBTREE API TEST ***
+INIT - Verify min/max node updates
+*** END OF TEST SPRBTREE 1 ***