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/*
* libc/stdlib/malloc/realloc.c -- realloc function
*
* Copyright (C) 2002 NEC Corporation
* Copyright (C) 2002 Miles Bader <miles@gnu.org>
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License. See the file COPYING.LIB in the main
* directory of this archive for more details.
*
* Written by Miles Bader <miles@gnu.org>
*/
#include <stdlib.h>
#include <string.h>
#include <errno.h>
/* Experimentally off - libc_hidden_proto(memcpy) */
#include "malloc.h"
#include "heap.h"
void *
realloc (void *mem, size_t new_size)
{
size_t size;
char *base_mem;
/* Check for special cases. */
if (! new_size)
{
free (mem);
return malloc (new_size);
}
if (! mem)
return malloc (new_size);
/* Normal realloc. */
base_mem = MALLOC_BASE (mem);
size = MALLOC_SIZE (mem);
/* Include extra space to record the size of the allocated block.
Also make sure that we're dealing in a multiple of the heap
allocation unit (SIZE is already guaranteed to be so).*/
new_size = HEAP_ADJUST_SIZE (new_size + MALLOC_HEADER_SIZE);
if (new_size < sizeof (struct heap_free_area))
/* Because we sometimes must use a freed block to hold a free-area node,
we must make sure that every allocated block can hold one. */
new_size = HEAP_ADJUST_SIZE (sizeof (struct heap_free_area));
MALLOC_DEBUG (1, "realloc: 0x%lx, %d (base = 0x%lx, total_size = %d)",
(long)mem, new_size, (long)base_mem, size);
if (new_size > size)
/* Grow the block. */
{
size_t extra = new_size - size;
__heap_do_lock (&__malloc_heap_lock);
extra = __heap_alloc_at (__malloc_heap, base_mem + size, extra);
__heap_do_unlock (&__malloc_heap_lock);
if (extra)
/* Record the changed size. */
MALLOC_SET_SIZE (base_mem, size + extra);
else
/* Our attempts to extend MEM in place failed, just
allocate-and-copy. */
{
void *new_mem = malloc (new_size - MALLOC_HEADER_SIZE);
if (new_mem)
{
memcpy (new_mem, mem, size - MALLOC_HEADER_SIZE);
free (mem);
}
mem = new_mem;
}
}
else if (new_size + MALLOC_REALLOC_MIN_FREE_SIZE <= size)
/* Shrink the block. */
{
__heap_do_lock (&__malloc_heap_lock);
__heap_free (__malloc_heap, base_mem + new_size, size - new_size);
__heap_do_unlock (&__malloc_heap_lock);
MALLOC_SET_SIZE (base_mem, new_size);
}
if (mem)
MALLOC_DEBUG (-1, "realloc: returning 0x%lx (base:0x%lx, total_size:%d)",
(long)mem, (long)MALLOC_BASE(mem), (long)MALLOC_SIZE(mem));
else
MALLOC_DEBUG (-1, "realloc: returning 0");
return mem;
}
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