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/*
* libc/stdlib/malloc/malloc.c -- malloc 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 <unistd.h>
#include <sys/mman.h>
#include "malloc.h"
#include "heap.h"
/* The malloc heap. We provide a bit of initial static space so that
programs can do a little mallocing without mmaping in more space. */
HEAP_DECLARE_STATIC_FREE_AREA (initial_fa, 256);
struct heap __malloc_heap = HEAP_INIT_WITH_FA (initial_fa);
#if defined(MALLOC_USE_LOCKING) && defined(MALLOC_USE_SBRK)
/* A lock protecting our use of sbrk. */
malloc_mutex_t __malloc_sbrk_lock;
#endif /* MALLOC_USE_LOCKING && MALLOC_USE_SBRK */
#ifdef MALLOC_DEBUGGING
int __malloc_debug = 0;
#endif
#ifdef __UCLIBC_UCLINUX_BROKEN_MUNMAP__
/* A list of all malloc_mmb structures describing blocsk that
malloc has mmapped, ordered by the block address. */
struct malloc_mmb *__malloc_mmapped_blocks = 0;
/* A heap used for allocating malloc_mmb structures. We could allocate
them from the main heap, but that tends to cause heap fragmentation in
annoying ways. */
HEAP_DECLARE_STATIC_FREE_AREA (initial_mmb_fa, 48); /* enough for 3 mmbs */
struct heap __malloc_mmb_heap = HEAP_INIT_WITH_FA (initial_mmb_fa);
# ifdef MALLOC_MMB_DEBUGGING
int __malloc_mmb_debug = 0;
# endif
#endif /* __UCLIBC_UCLINUX_BROKEN_MUNMAP__ */
static void *
malloc_from_heap (size_t size, struct heap *heap)
{
void *mem;
MALLOC_DEBUG ("malloc: %d bytes\n", size);
/* Include extra space to record the size of the allocated block. */
size += MALLOC_HEADER_SIZE;
__heap_lock (heap);
/* First try to get memory that's already in our heap. */
mem = __heap_alloc (heap, &size);
if (unlikely (! mem))
/* We couldn't allocate from the heap, so grab some more
from the system, add it to the heap, and try again. */
{
/* If we're trying to allocate a block bigger than the default
MALLOC_HEAP_EXTEND_SIZE, make sure we get enough to hold it. */
void *block;
size_t block_size
= (size < MALLOC_HEAP_EXTEND_SIZE
? MALLOC_HEAP_EXTEND_SIZE
: MALLOC_ROUND_UP_TO_PAGE_SIZE (size));
#ifdef MALLOC_USE_SBRK
/* Get the sbrk lock while we've still got the heap lock. */
__malloc_lock_sbrk ();
#endif
/* Don't hold the heap lock during the syscall, so that small
allocations in a different thread may succeed while we're
blocked. */
__heap_unlock (heap);
/* Allocate the new heap block. */
#ifdef MALLOC_USE_SBRK
/* Use sbrk we can, as it's faster than mmap, and guarantees
contiguous allocation. */
block = sbrk (block_size);
if (likely (block != (void *)-1))
{
/* Because sbrk can return results of arbitrary
alignment, align the result to a MALLOC_ALIGNMENT boundary. */
long aligned_block = MALLOC_ROUND_UP ((long)block, MALLOC_ALIGNMENT);
if (block != (void *)aligned_block)
/* Have to adjust. We should only have to actually do this
the first time (after which we will have aligned the brk
correctly). */
{
/* Move the brk to reflect the alignment; our next allocation
should start on exactly the right alignment. */
sbrk (aligned_block - (long)block);
block = (void *)aligned_block;
}
}
__malloc_unlock_sbrk ();
#else /* !MALLOC_USE_SBRK */
/* Otherwise, use mmap. */
block = mmap (0, block_size, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, 0, 0);
#endif /* MALLOC_USE_SBRK */
/* Get back the heap lock. */
__heap_lock (heap);
if (likely (block != (void *)-1))
{
#if !defined(MALLOC_USE_SBRK) && defined(__UCLIBC_UCLINUX_BROKEN_MUNMAP__)
struct malloc_mmb *mmb, *prev_mmb, *new_mmb;
#endif /* !MALLOC_USE_SBRK && __UCLIBC_UCLINUX_BROKEN_MUNMAP__ */
MALLOC_DEBUG (" adding memory: 0x%lx - 0x%lx (%d bytes)\n",
(long)block, (long)block + block_size, block_size);
/* Put BLOCK into the heap. */
__heap_free (heap, block, block_size);
#if !defined(MALLOC_USE_SBRK) && defined(__UCLIBC_UCLINUX_BROKEN_MUNMAP__)
/* Insert a record of this allocation in sorted order into the
__malloc_mmapped_blocks list. */
for (prev_mmb = 0, mmb = __malloc_mmapped_blocks;
mmb;
prev_mmb = mmb, mmb = mmb->next)
if (block < mmb->mem)
break;
new_mmb = malloc_from_heap (sizeof *new_mmb, &__malloc_mmb_heap);
new_mmb->next = mmb;
new_mmb->mem = block;
new_mmb->size = block_size;
MALLOC_MMB_DEBUG (" new mmb at 0x%x: 0x%x[%d]\n",
(unsigned)new_mmb,
(unsigned)new_mmb->mem, block_size);
if (prev_mmb)
prev_mmb->next = new_mmb;
else
__malloc_mmapped_blocks = new_mmb;
#endif /* !MALLOC_USE_SBRK && __UCLIBC_UCLINUX_BROKEN_MUNMAP__ */
/* Try again to allocate. */
mem = __heap_alloc (heap, &size);
}
}
__heap_unlock (heap);
if (likely (mem))
/* Record the size of the block and get the user address. */
{
mem = MALLOC_SETUP (mem, size);
MALLOC_DEBUG (" malloc: returning 0x%lx (base:0x%lx, total_size:%d)\n",
(long)mem, (long)MALLOC_BASE(mem), (long)MALLOC_SIZE(mem));
}
return mem;
}
void *
malloc (size_t size)
{
return malloc_from_heap (size, &__malloc_heap);
}
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