From f68fa9d36488b6c88e06d509cb9694ed03b4084a Mon Sep 17 00:00:00 2001
From: Ingo Weinhold <ingo_weinhold@gmx.de>
Date: Sun, 2 Nov 2008 02:59:15 +0000
Subject: [PATCH] Implemented realloc().

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@28454 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 src/system/runtime_loader/heap.cpp | 37 +++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/src/system/runtime_loader/heap.cpp b/src/system/runtime_loader/heap.cpp
index f42ba8a185..03346a978e 100644
--- a/src/system/runtime_loader/heap.cpp
+++ b/src/system/runtime_loader/heap.cpp
@@ -24,7 +24,7 @@ static const size_t kInitialHeapSize = 65536;
  * linked list).
  * When memory is allocated, the smallest free chunk that contains
  * the requested size is split (or taken as a whole if it can't be
- * splitted anymore), and it's lower half will be removed from the 
+ * splitted anymore), and it's lower half will be removed from the
  * free list.
  * The free list is ordered by size, starting with the smallest
  * free chunk available. When a chunk is freed, it will be joint
@@ -120,7 +120,7 @@ free_chunk::Join(free_chunk *chunk)
 }
 
 
-void 
+void
 free_chunk::Remove(free_chunk *previous)
 {
 	if (previous == NULL) {
@@ -143,7 +143,7 @@ free_chunk::Remove(free_chunk *previous)
 }
 
 
-void 
+void
 free_chunk::Enqueue()
 {
 	free_chunk *chunk = sFreeAnchor.next, *last = &sFreeAnchor;
@@ -237,10 +237,31 @@ dump_chunks(void)
 
 
 void *
-realloc(void *buffer, size_t newSize)
+realloc(void *allocation, size_t newSize)
 {
-	// not implemented
-	return NULL;
+	// free, if new size is 0
+	if (newSize == 0) {
+		free(allocation);
+		return NULL;
+	}
+
+	// just malloc(), if no previous allocation
+	if (allocation == NULL)
+		return malloc(newSize);
+
+	// we're lazy and don't shrink allocations
+	free_chunk* chunk = free_chunk::SetToAllocated(allocation);
+	if (chunk->Size() >= newSize)
+		return allocation;
+
+	// the allocation needs to grow -- allocate a new one and memcpy()
+	void* newAllocation = malloc(newSize);
+	if (newAllocation != NULL) {
+		memcpy(newAllocation, allocation, chunk->Size());
+		free(allocation);
+	}
+
+	return newAllocation;
 }
 
 
@@ -322,7 +343,7 @@ free(void *allocated)
 			// remove the joined chunk from the list
 			last->next = freedChunk->next;
 			chunk = last;
-			
+
 			if (++joinCount == 2)
 				break;
 		}
@@ -331,7 +352,7 @@ free(void *allocated)
 		chunk = chunk->next;
 	}
 
-	// enqueue the link at the right position; the 
+	// enqueue the link at the right position; the
 	// free link queue is ordered by size
 
 	freedChunk->Enqueue();