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realloc(): When realloc() has to fall back to calling malloc(), size including overhead was being provided to malloc(), causing a slightly larger allocation than needed. Noted by initialkjc@yahoo.com

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Gregory Nutt 2017-03-28 07:23:46 -06:00
parent 91f96b6ecb
commit 0064dc52e5
1 changed files with 9 additions and 8 deletions
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17
mm/mm_heap/mm_realloc.c
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@ -1,7 +1,7 @@
/****************************************************************************
* mm/mm_heap/mm_realloc.c
*
* Copyright (C) 2007, 2009, 2013-2014 Gregory Nutt. All rights reserved.
* Copyright (C) 2007, 2009, 2013-2014, 2017 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
@ -79,6 +79,7 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
FAR struct mm_allocnode_s *oldnode;
FAR struct mm_freenode_s *prev;
FAR struct mm_freenode_s *next;
size_t newsize;
size_t oldsize;
size_t prevsize = 0;
size_t nextsize = 0;
@ -86,7 +87,7 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
/* If oldmem is NULL, then realloc is equivalent to malloc */
if (!oldmem)
if (oldmem == NULL)
{
return mm_malloc(heap, size);
}
@ -103,7 +104,7 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
* (2) to make sure that it is an even multiple of our granule size.
*/
size = MM_ALIGN_UP(size + SIZEOF_MM_ALLOCNODE);
newsize = MM_ALIGN_UP(size + SIZEOF_MM_ALLOCNODE);
/* Map the memory chunk into an allocated node structure */
@ -116,15 +117,15 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
/* Check if this is a request to reduce the size of the allocation. */
oldsize = oldnode->size;
if (size <= oldsize)
if (newsize <= oldsize)
{
/* Handle the special case where we are not going to change the size
* of the allocation.
*/
if (size < oldsize)
if (newsize < oldsize)
{
mm_shrinkchunk(heap, oldnode, size);
mm_shrinkchunk(heap, oldnode, newsize);
}
/* Then return the original address */
@ -152,9 +153,9 @@ FAR void *mm_realloc(FAR struct mm_heap_s *heap, FAR void *oldmem,
/* Now, check if we can extend the current allocation or not */
if (nextsize + prevsize + oldsize >= size)
if (nextsize + prevsize + oldsize >= newsize)
{
size_t needed = size - oldsize;
size_t needed = newsize - oldsize;
size_t takeprev = 0;
size_t takenext = 0;