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uClibc/libc/stdlib/malloc/malloc.c
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/* | |
* libc/stdlib/malloc/malloc.c -- malloc function | |
* | |
* Copyright (C) 2002,03 NEC Electronics Corporation | |
* Copyright (C) 2002,03 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 <errno.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_free_area *__malloc_heap = HEAP_INIT_WITH_FA (initial_fa); | |
#ifdef HEAP_USE_LOCKING | |
__UCLIBC_MUTEX_INIT(__malloc_heap_lock,PTHREAD_MUTEX_INITIALIZER); | |
#endif | |
#if defined(MALLOC_USE_LOCKING) && defined(MALLOC_USE_SBRK) | |
/* A lock protecting our use of sbrk. */ | |
__UCLIBC_MUTEX(__malloc_sbrk_lock); | |
#endif /* MALLOC_USE_LOCKING && MALLOC_USE_SBRK */ | |
#ifdef __UCLIBC_UCLINUX_BROKEN_MUNMAP__ | |
/* A list of all malloc_mmb structures describing blocks 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_free_area *__malloc_mmb_heap = HEAP_INIT_WITH_FA (initial_mmb_fa); | |
#ifdef HEAP_USE_LOCKING | |
__UCLIBC_MUTEX_INIT(__malloc_mmb_heap_lock,PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP); | |
#endif | |
#endif /* __UCLIBC_UCLINUX_BROKEN_MUNMAP__ */ | |
#ifdef HEAP_USE_LOCKING | |
#define malloc_from_heap(size, heap, lck) __malloc_from_heap(size, heap, lck) | |
#else | |
#define malloc_from_heap(size, heap, lck) __malloc_from_heap(size, heap) | |
#endif | |
static void * | |
__malloc_from_heap (size_t size, struct heap_free_area **heap | |
#ifdef HEAP_USE_LOCKING | |
, __UCLIBC_MUTEX_TYPE *heap_lock | |
#endif | |
) | |
{ | |
void *mem; | |
MALLOC_DEBUG (1, "malloc: %d bytes", size); | |
/* Include extra space to record the size of the allocated block. */ | |
size += MALLOC_HEADER_SIZE; | |
__heap_lock (heap_lock); | |
/* First try to get memory that's already in our heap. */ | |
mem = __heap_alloc (heap, &size); | |
__heap_unlock (heap_lock); | |
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)); | |
/* Allocate the new heap block. */ | |
#ifdef MALLOC_USE_SBRK | |
__malloc_lock_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. */ | |
#ifdef __ARCH_USE_MMU__ | |
block = mmap ((void *)0, block_size, PROT_READ | PROT_WRITE, | |
MAP_PRIVATE | MAP_ANONYMOUS, 0, 0); | |
#else | |
block = mmap ((void *)0, block_size, PROT_READ | PROT_WRITE, | |
MAP_SHARED | MAP_ANONYMOUS | MAP_UNINITIALIZED, 0, 0); | |
#endif | |
#endif /* MALLOC_USE_SBRK */ | |
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_DEBUG (1, "adding system memory to heap: 0x%lx - 0x%lx (%d bytes)", | |
(long)block, (long)block + block_size, block_size); | |
/* Get back the heap lock. */ | |
__heap_lock (heap_lock); | |
/* Put BLOCK into the heap. */ | |
__heap_free (heap, block, block_size); | |
MALLOC_DEBUG_INDENT (-1); | |
/* Try again to allocate. */ | |
mem = __heap_alloc (heap, &size); | |
#if !defined(MALLOC_USE_SBRK) && defined(__UCLIBC_UCLINUX_BROKEN_MUNMAP__) | |
/* Insert a record of BLOCK in sorted order into the | |
__malloc_mmapped_blocks list. */ | |
new_mmb = malloc_from_heap (sizeof *new_mmb, &__malloc_mmb_heap, &__malloc_mmb_heap_lock); | |
for (prev_mmb = 0, mmb = __malloc_mmapped_blocks; | |
mmb; | |
prev_mmb = mmb, mmb = mmb->next) | |
if (block < mmb->mem) | |
break; | |
new_mmb->next = mmb; | |
new_mmb->mem = block; | |
new_mmb->size = block_size; | |
if (prev_mmb) | |
prev_mmb->next = new_mmb; | |
else | |
__malloc_mmapped_blocks = new_mmb; | |
MALLOC_MMB_DEBUG (0, "new mmb at 0x%x: 0x%x[%d]", | |
(unsigned)new_mmb, | |
(unsigned)new_mmb->mem, block_size); | |
#endif /* !MALLOC_USE_SBRK && __UCLIBC_UCLINUX_BROKEN_MUNMAP__ */ | |
__heap_unlock (heap_lock); | |
} | |
} | |
if (likely (mem)) | |
/* Record the size of the block and get the user address. */ | |
{ | |
mem = MALLOC_SETUP (mem, size); | |
MALLOC_DEBUG (-1, "malloc: returning 0x%lx (base:0x%lx, total_size:%ld)", | |
(long)mem, (long)MALLOC_BASE(mem), (long)MALLOC_SIZE(mem)); | |
} | |
else | |
MALLOC_DEBUG (-1, "malloc: returning 0"); | |
return mem; | |
} | |
void * | |
malloc (size_t size) | |
{ | |
void *mem; | |
#ifdef MALLOC_DEBUGGING | |
static smallint debugging_initialized; | |
if (! debugging_initialized) | |
{ | |
debugging_initialized = 1; | |
__malloc_debug_init (); | |
} | |
if (__malloc_check) | |
__heap_check (__malloc_heap, "malloc"); | |
#endif | |
#ifdef __MALLOC_GLIBC_COMPAT__ | |
if (unlikely (size == 0)) | |
size++; | |
#else | |
/* Some programs will call malloc (0). Lets be strict and return NULL */ | |
if (unlikely (size == 0)) | |
goto oom; | |
#endif | |
/* Check if they are doing something dumb like malloc(-1) */ | |
if (unlikely(((unsigned long)size > (unsigned long)(MALLOC_HEADER_SIZE*-2)))) | |
goto oom; | |
mem = malloc_from_heap (size, &__malloc_heap, &__malloc_heap_lock); | |
if (unlikely (!mem)) | |
{ | |
oom: | |
__set_errno (ENOMEM); | |
return 0; | |
} | |
return mem; | |
} |