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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 <sys/mman.h>
#include "malloc.h"
#include "heap.h"
void *realloc (void *mem, size_t new_size)
{
if (! mem)
return malloc (new_size);
else
{
void *base_mem = (size_t *)mem - 1;
size_t size = *(size_t *)base_mem;
MALLOC_DEBUG ("realloc: 0x%lx, %d (base = 0x%lx, total_size = %d)\n",
(long)mem, new_size, (long)base_mem, size);
if (new_size <= size)
return mem;
else
{
void *new_mem = 0;
size_t ext_size = new_size - size;
void *ext_addr = (char *)base_mem + ext_size;
if (size >= MALLOC_MMAP_THRESHOLD)
/* Try to extend this block in place using mmap. */
{
ext_size += MALLOC_ROUND_UP_TO_PAGE_SIZE (ext_size);
new_mem = mmap (ext_addr, ext_size, PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_SHARED | MAP_ANONYMOUS, 0, 0);
if (new_mem == MAP_FAILED)
/* Can't do it. */
ext_size = 0;
}
else
ext_size = __heap_alloc_at (&__malloc_heap, ext_addr, ext_size);
if (! ext_size)
/* Our attempts to extend MEM in place failed, just
allocate-and-copy. */
{
new_mem = malloc (new_size);
if (new_mem)
{
memcpy (new_mem, mem, size);
free (mem);
}
}
if (new_mem)
MALLOC_DEBUG (" realloc: returning 0x%lx"
" (base:0x%lx, total_size:%d)\n",
(long)new_mem, (long)new_mem - sizeof(size_t), size);
return new_mem;
}
}
}
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