From 4d73c382ab83222c9ea10194e4270f1259c517b2 Mon Sep 17 00:00:00 2001
From: Sebastian Huber <sebastian.huber@embedded-brains.de>
Date: Wed, 25 Aug 2010 12:35:52 +0000
Subject: 2010-08-25	Sebastian Huber <sebastian.huber@embedded-brains.de>

	PR 1672/cpukit
	* score/include/rtems/score/heap.h, score/src/heap.c,
	score/src/heapallocate.c, score/src/heapextend.c,
	score/src/heapfree.c, score/src/heapresizeblock.c,
	score/src/heapsizeofuserarea.c: Added heap protection in case
	RTEMS_DEBUG is defined.
---
 cpukit/score/src/heapfree.c | 93 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 91 insertions(+), 2 deletions(-)

(limited to 'cpukit/score/src/heapfree.c')

diff --git a/cpukit/score/src/heapfree.c b/cpukit/score/src/heapfree.c
index 48b54293ea..27e853d5bb 100644
--- a/cpukit/score/src/heapfree.c
+++ b/cpukit/score/src/heapfree.c
@@ -22,9 +22,89 @@
 #endif
 
 #include <rtems/system.h>
-#include <rtems/score/sysstate.h>
 #include <rtems/score/heap.h>
 
+#ifndef HEAP_PROTECTION
+  #define _Heap_Protection_determine_block_free( heap, block ) true
+#else
+  static void _Heap_Protection_delay_block_free(
+    Heap_Control *heap,
+    Heap_Block *block
+  )
+  {
+    uintptr_t *const pattern_begin = (uintptr_t *)
+      _Heap_Alloc_area_of_block( block );
+    uintptr_t *const pattern_end = (uintptr_t *)
+      ((uintptr_t) block + _Heap_Block_size( block ) + HEAP_ALLOC_BONUS);
+    uintptr_t const delayed_free_block_count = 
+      heap->Protection.delayed_free_block_count;
+    uintptr_t *current = NULL;
+
+    block->Protection_begin.next_delayed_free_block = block;
+    block->Protection_begin.task = _Thread_Executing;
+
+    if ( delayed_free_block_count > 0 ) {
+      Heap_Block *const last = heap->Protection.last_delayed_free_block;
+      
+      last->Protection_begin.next_delayed_free_block = block;
+    } else {
+      heap->Protection.first_delayed_free_block = block;
+    }
+    heap->Protection.last_delayed_free_block = block;
+    heap->Protection.delayed_free_block_count = delayed_free_block_count + 1;
+
+    for ( current = pattern_begin; current != pattern_end; ++current ) {
+      *current = HEAP_FREE_PATTERN;
+    }
+  }
+
+  static void _Heap_Protection_check_free_block(
+    Heap_Control *heap,
+    Heap_Block *block
+  )
+  {
+    uintptr_t *const pattern_begin = (uintptr_t *)
+      _Heap_Alloc_area_of_block( block );
+    uintptr_t *const pattern_end = (uintptr_t *)
+      ((uintptr_t) block + _Heap_Block_size( block ) + HEAP_ALLOC_BONUS);
+    uintptr_t *current = NULL;
+
+    for ( current = pattern_begin; current != pattern_end; ++current ) {
+      if ( *current != HEAP_FREE_PATTERN ) {
+        _Heap_Protection_block_error( heap, block );
+        break;
+      }
+    }
+  }
+
+  static bool _Heap_Protection_determine_block_free(
+    Heap_Control *heap,
+    Heap_Block *block
+  )
+  {
+    bool do_free = true;
+
+    /*
+     * Sometimes after a free the allocated area is still in use.  An example
+     * is the task stack of a thread that deletes itself.  The thread dispatch
+     * disable level is a way to detect this use case.
+     */
+    if ( _Thread_Dispatch_disable_level == 0 ) {
+      Heap_Block *const next = block->Protection_begin.next_delayed_free_block;
+      if ( next == NULL ) {
+        _Heap_Protection_delay_block_free( heap, block );
+        do_free = false;
+      } else if ( next == HEAP_PROTECTION_OBOLUS ) {
+        _Heap_Protection_check_free_block( heap, block );
+      } else {
+        _Heap_Protection_block_error( heap, block );
+      }
+    }
+
+    return do_free;
+  }
+#endif
+
 bool _Heap_Free( Heap_Control *heap, void *alloc_begin_ptr )
 {
   Heap_Statistics *const stats = &heap->stats;
@@ -36,6 +116,8 @@ bool _Heap_Free( Heap_Control *heap, void *alloc_begin_ptr )
   uintptr_t next_block_size = 0;
   bool next_is_free = false;
 
+  _Heap_Protection_block_check( heap, block );
+
   if ( !_Heap_Is_block_in_heap( heap, block ) ) {
     return false;
   }
@@ -43,16 +125,23 @@ bool _Heap_Free( Heap_Control *heap, void *alloc_begin_ptr )
   block_size = _Heap_Block_size( block );
   next_block = _Heap_Block_at( block, block_size );
 
+  _Heap_Protection_block_check( heap, next_block );
+
   if ( !_Heap_Is_block_in_heap( heap, next_block ) ) {
     _HAssert( false );
     return false;
   }
 
   if ( !_Heap_Is_prev_used( next_block ) ) {
-    _HAssert( false );
+    _Heap_Protection_block_error( heap, block );
+
     return false;
   }
 
+  if ( !_Heap_Protection_determine_block_free( heap, block ) ) {
+    return true;
+  }
+
   next_block_size = _Heap_Block_size( next_block );
   next_is_free = next_block != heap->last_block
     && !_Heap_Is_prev_used( _Heap_Block_at( next_block, next_block_size ));
-- 
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