3 #if defined(CONFIG_UNIT_TEST)
12 static void malloc_update_mallinfo (void);
13 void malloc_stats (void);
15 static void malloc_update_mallinfo ();
20 DECLARE_GLOBAL_DATA_PTR;
23 Emulation of sbrk for WIN32
24 All code within the ifdef WIN32 is untested by me.
26 Thanks to Martin Fong and others for supplying this.
32 #define AlignPage(add) (((add) + (malloc_getpagesize-1)) & \
33 ~(malloc_getpagesize-1))
34 #define AlignPage64K(add) (((add) + (0x10000 - 1)) & ~(0x10000 - 1))
36 /* resrve 64MB to insure large contiguous space */
37 #define RESERVED_SIZE (1024*1024*64)
38 #define NEXT_SIZE (2048*1024)
39 #define TOP_MEMORY ((unsigned long)2*1024*1024*1024)
42 typedef struct GmListElement GmListElement;
50 static GmListElement* head = 0;
51 static unsigned int gNextAddress = 0;
52 static unsigned int gAddressBase = 0;
53 static unsigned int gAllocatedSize = 0;
56 GmListElement* makeGmListElement (void* bas)
59 this = (GmListElement*)(void*)LocalAlloc (0, sizeof (GmListElement));
73 assert ( (head == NULL) || (head->base == (void*)gAddressBase));
74 if (gAddressBase && (gNextAddress - gAddressBase))
76 rval = VirtualFree ((void*)gAddressBase,
77 gNextAddress - gAddressBase,
83 GmListElement* next = head->next;
84 rval = VirtualFree (head->base, 0, MEM_RELEASE);
92 void* findRegion (void* start_address, unsigned long size)
94 MEMORY_BASIC_INFORMATION info;
95 if (size >= TOP_MEMORY) return NULL;
97 while ((unsigned long)start_address + size < TOP_MEMORY)
99 VirtualQuery (start_address, &info, sizeof (info));
100 if ((info.State == MEM_FREE) && (info.RegionSize >= size))
101 return start_address;
104 /* Requested region is not available so see if the */
105 /* next region is available. Set 'start_address' */
106 /* to the next region and call 'VirtualQuery()' */
109 start_address = (char*)info.BaseAddress + info.RegionSize;
111 /* Make sure we start looking for the next region */
112 /* on the *next* 64K boundary. Otherwise, even if */
113 /* the new region is free according to */
114 /* 'VirtualQuery()', the subsequent call to */
115 /* 'VirtualAlloc()' (which follows the call to */
116 /* this routine in 'wsbrk()') will round *down* */
117 /* the requested address to a 64K boundary which */
118 /* we already know is an address in the */
119 /* unavailable region. Thus, the subsequent call */
120 /* to 'VirtualAlloc()' will fail and bring us back */
121 /* here, causing us to go into an infinite loop. */
124 (void *) AlignPage64K((unsigned long) start_address);
132 void* wsbrk (long size)
137 if (gAddressBase == 0)
139 gAllocatedSize = max (RESERVED_SIZE, AlignPage (size));
140 gNextAddress = gAddressBase =
141 (unsigned int)VirtualAlloc (NULL, gAllocatedSize,
142 MEM_RESERVE, PAGE_NOACCESS);
143 } else if (AlignPage (gNextAddress + size) > (gAddressBase +
146 long new_size = max (NEXT_SIZE, AlignPage (size));
147 void* new_address = (void*)(gAddressBase+gAllocatedSize);
150 new_address = findRegion (new_address, new_size);
155 gAddressBase = gNextAddress =
156 (unsigned int)VirtualAlloc (new_address, new_size,
157 MEM_RESERVE, PAGE_NOACCESS);
158 /* repeat in case of race condition */
159 /* The region that we found has been snagged */
160 /* by another thread */
162 while (gAddressBase == 0);
164 assert (new_address == (void*)gAddressBase);
166 gAllocatedSize = new_size;
168 if (!makeGmListElement ((void*)gAddressBase))
171 if ((size + gNextAddress) > AlignPage (gNextAddress))
174 res = VirtualAlloc ((void*)AlignPage (gNextAddress),
175 (size + gNextAddress -
176 AlignPage (gNextAddress)),
177 MEM_COMMIT, PAGE_READWRITE);
181 tmp = (void*)gNextAddress;
182 gNextAddress = (unsigned int)tmp + size;
187 unsigned int alignedGoal = AlignPage (gNextAddress + size);
188 /* Trim by releasing the virtual memory */
189 if (alignedGoal >= gAddressBase)
191 VirtualFree ((void*)alignedGoal, gNextAddress - alignedGoal,
193 gNextAddress = gNextAddress + size;
194 return (void*)gNextAddress;
198 VirtualFree ((void*)gAddressBase, gNextAddress - gAddressBase,
200 gNextAddress = gAddressBase;
206 return (void*)gNextAddress;
221 INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */
222 INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */
223 struct malloc_chunk* fd; /* double links -- used only if free. */
224 struct malloc_chunk* bk;
225 } __attribute__((__may_alias__)) ;
227 typedef struct malloc_chunk* mchunkptr;
231 malloc_chunk details:
233 (The following includes lightly edited explanations by Colin Plumb.)
235 Chunks of memory are maintained using a `boundary tag' method as
236 described in e.g., Knuth or Standish. (See the paper by Paul
237 Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
238 survey of such techniques.) Sizes of free chunks are stored both
239 in the front of each chunk and at the end. This makes
240 consolidating fragmented chunks into bigger chunks very fast. The
241 size fields also hold bits representing whether chunks are free or
244 An allocated chunk looks like this:
247 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
248 | Size of previous chunk, if allocated | |
249 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
250 | Size of chunk, in bytes |P|
251 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
252 | User data starts here... .
254 . (malloc_usable_space() bytes) .
256 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
258 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
261 Where "chunk" is the front of the chunk for the purpose of most of
262 the malloc code, but "mem" is the pointer that is returned to the
263 user. "Nextchunk" is the beginning of the next contiguous chunk.
265 Chunks always begin on even word boundries, so the mem portion
266 (which is returned to the user) is also on an even word boundary, and
267 thus double-word aligned.
269 Free chunks are stored in circular doubly-linked lists, and look like this:
271 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
272 | Size of previous chunk |
273 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
274 `head:' | Size of chunk, in bytes |P|
275 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
276 | Forward pointer to next chunk in list |
277 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
278 | Back pointer to previous chunk in list |
279 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
280 | Unused space (may be 0 bytes long) .
283 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
284 `foot:' | Size of chunk, in bytes |
285 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
287 The P (PREV_INUSE) bit, stored in the unused low-order bit of the
288 chunk size (which is always a multiple of two words), is an in-use
289 bit for the *previous* chunk. If that bit is *clear*, then the
290 word before the current chunk size contains the previous chunk
291 size, and can be used to find the front of the previous chunk.
292 (The very first chunk allocated always has this bit set,
293 preventing access to non-existent (or non-owned) memory.)
295 Note that the `foot' of the current chunk is actually represented
296 as the prev_size of the NEXT chunk. (This makes it easier to
297 deal with alignments etc).
299 The two exceptions to all this are
301 1. The special chunk `top', which doesn't bother using the
302 trailing size field since there is no
303 next contiguous chunk that would have to index off it. (After
304 initialization, `top' is forced to always exist. If it would
305 become less than MINSIZE bytes long, it is replenished via
308 2. Chunks allocated via mmap, which have the second-lowest-order
309 bit (IS_MMAPPED) set in their size fields. Because they are
310 never merged or traversed from any other chunk, they have no
311 foot size or inuse information.
313 Available chunks are kept in any of several places (all declared below):
315 * `av': An array of chunks serving as bin headers for consolidated
316 chunks. Each bin is doubly linked. The bins are approximately
317 proportionally (log) spaced. There are a lot of these bins
318 (128). This may look excessive, but works very well in
319 practice. All procedures maintain the invariant that no
320 consolidated chunk physically borders another one. Chunks in
321 bins are kept in size order, with ties going to the
322 approximately least recently used chunk.
324 The chunks in each bin are maintained in decreasing sorted order by
325 size. This is irrelevant for the small bins, which all contain
326 the same-sized chunks, but facilitates best-fit allocation for
327 larger chunks. (These lists are just sequential. Keeping them in
328 order almost never requires enough traversal to warrant using
329 fancier ordered data structures.) Chunks of the same size are
330 linked with the most recently freed at the front, and allocations
331 are taken from the back. This results in LRU or FIFO allocation
332 order, which tends to give each chunk an equal opportunity to be
333 consolidated with adjacent freed chunks, resulting in larger free
334 chunks and less fragmentation.
336 * `top': The top-most available chunk (i.e., the one bordering the
337 end of available memory) is treated specially. It is never
338 included in any bin, is used only if no other chunk is
339 available, and is released back to the system if it is very
340 large (see M_TRIM_THRESHOLD).
342 * `last_remainder': A bin holding only the remainder of the
343 most recently split (non-top) chunk. This bin is checked
344 before other non-fitting chunks, so as to provide better
345 locality for runs of sequentially allocated chunks.
347 * Implicitly, through the host system's memory mapping tables.
348 If supported, requests greater than a threshold are usually
349 serviced via calls to mmap, and then later released via munmap.
353 /* sizes, alignments */
355 #define SIZE_SZ (sizeof(INTERNAL_SIZE_T))
356 #define MALLOC_ALIGNMENT (SIZE_SZ + SIZE_SZ)
357 #define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1)
358 #define MINSIZE (sizeof(struct malloc_chunk))
360 /* conversion from malloc headers to user pointers, and back */
362 #define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ))
363 #define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))
365 /* pad request bytes into a usable size */
367 #define request2size(req) \
368 (((long)((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \
369 (long)(MINSIZE + MALLOC_ALIGN_MASK)) ? MINSIZE : \
370 (((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) & ~(MALLOC_ALIGN_MASK)))
372 /* Check if m has acceptable alignment */
374 #define aligned_OK(m) (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0)
380 Physical chunk operations
384 /* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
386 #define PREV_INUSE 0x1
388 /* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
390 #define IS_MMAPPED 0x2
392 /* Bits to mask off when extracting size */
394 #define SIZE_BITS (PREV_INUSE|IS_MMAPPED)
397 /* Ptr to next physical malloc_chunk. */
399 #define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) ))
401 /* Ptr to previous physical malloc_chunk */
403 #define prev_chunk(p)\
404 ((mchunkptr)( ((char*)(p)) - ((p)->prev_size) ))
407 /* Treat space at ptr + offset as a chunk */
409 #define chunk_at_offset(p, s) ((mchunkptr)(((char*)(p)) + (s)))
415 Dealing with use bits
418 /* extract p's inuse bit */
421 ((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE)
423 /* extract inuse bit of previous chunk */
425 #define prev_inuse(p) ((p)->size & PREV_INUSE)
427 /* check for mmap()'ed chunk */
429 #define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED)
431 /* set/clear chunk as in use without otherwise disturbing */
433 #define set_inuse(p)\
434 ((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE
436 #define clear_inuse(p)\
437 ((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE)
439 /* check/set/clear inuse bits in known places */
441 #define inuse_bit_at_offset(p, s)\
442 (((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE)
444 #define set_inuse_bit_at_offset(p, s)\
445 (((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE)
447 #define clear_inuse_bit_at_offset(p, s)\
448 (((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE))
454 Dealing with size fields
457 /* Get size, ignoring use bits */
459 #define chunksize(p) ((p)->size & ~(SIZE_BITS))
461 /* Set size at head, without disturbing its use bit */
463 #define set_head_size(p, s) ((p)->size = (((p)->size & PREV_INUSE) | (s)))
465 /* Set size/use ignoring previous bits in header */
467 #define set_head(p, s) ((p)->size = (s))
469 /* Set size at footer (only when chunk is not in use) */
471 #define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_size = (s))
480 The bins, `av_' are an array of pairs of pointers serving as the
481 heads of (initially empty) doubly-linked lists of chunks, laid out
482 in a way so that each pair can be treated as if it were in a
483 malloc_chunk. (This way, the fd/bk offsets for linking bin heads
484 and chunks are the same).
486 Bins for sizes < 512 bytes contain chunks of all the same size, spaced
487 8 bytes apart. Larger bins are approximately logarithmically
488 spaced. (See the table below.) The `av_' array is never mentioned
489 directly in the code, but instead via bin access macros.
498 2 bins of size 262144
499 1 bin of size what's left
501 There is actually a little bit of slop in the numbers in bin_index
502 for the sake of speed. This makes no difference elsewhere.
504 The special chunks `top' and `last_remainder' get their own bins,
505 (this is implemented via yet more trickery with the av_ array),
506 although `top' is never properly linked to its bin since it is
507 always handled specially.
511 #define NAV 128 /* number of bins */
513 typedef struct malloc_chunk* mbinptr;
517 #define bin_at(i) ((mbinptr)((char*)&(av_[2*(i) + 2]) - 2*SIZE_SZ))
518 #define next_bin(b) ((mbinptr)((char*)(b) + 2 * sizeof(mbinptr)))
519 #define prev_bin(b) ((mbinptr)((char*)(b) - 2 * sizeof(mbinptr)))
522 The first 2 bins are never indexed. The corresponding av_ cells are instead
523 used for bookkeeping. This is not to save space, but to simplify
524 indexing, maintain locality, and avoid some initialization tests.
527 #define top (av_[2]) /* The topmost chunk */
528 #define last_remainder (bin_at(1)) /* remainder from last split */
532 Because top initially points to its own bin with initial
533 zero size, thus forcing extension on the first malloc request,
534 we avoid having any special code in malloc to check whether
535 it even exists yet. But we still need to in malloc_extend_top.
538 #define initial_top ((mchunkptr)(bin_at(0)))
540 /* Helper macro to initialize bins */
542 #define IAV(i) bin_at(i), bin_at(i)
544 static mbinptr av_[NAV * 2 + 2] = {
546 IAV(0), IAV(1), IAV(2), IAV(3), IAV(4), IAV(5), IAV(6), IAV(7),
547 IAV(8), IAV(9), IAV(10), IAV(11), IAV(12), IAV(13), IAV(14), IAV(15),
548 IAV(16), IAV(17), IAV(18), IAV(19), IAV(20), IAV(21), IAV(22), IAV(23),
549 IAV(24), IAV(25), IAV(26), IAV(27), IAV(28), IAV(29), IAV(30), IAV(31),
550 IAV(32), IAV(33), IAV(34), IAV(35), IAV(36), IAV(37), IAV(38), IAV(39),
551 IAV(40), IAV(41), IAV(42), IAV(43), IAV(44), IAV(45), IAV(46), IAV(47),
552 IAV(48), IAV(49), IAV(50), IAV(51), IAV(52), IAV(53), IAV(54), IAV(55),
553 IAV(56), IAV(57), IAV(58), IAV(59), IAV(60), IAV(61), IAV(62), IAV(63),
554 IAV(64), IAV(65), IAV(66), IAV(67), IAV(68), IAV(69), IAV(70), IAV(71),
555 IAV(72), IAV(73), IAV(74), IAV(75), IAV(76), IAV(77), IAV(78), IAV(79),
556 IAV(80), IAV(81), IAV(82), IAV(83), IAV(84), IAV(85), IAV(86), IAV(87),
557 IAV(88), IAV(89), IAV(90), IAV(91), IAV(92), IAV(93), IAV(94), IAV(95),
558 IAV(96), IAV(97), IAV(98), IAV(99), IAV(100), IAV(101), IAV(102), IAV(103),
559 IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111),
560 IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119),
561 IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127)
564 #ifdef CONFIG_NEEDS_MANUAL_RELOC
565 static void malloc_bin_reloc(void)
567 mbinptr *p = &av_[2];
570 for (i = 2; i < ARRAY_SIZE(av_); ++i, ++p)
571 *p = (mbinptr)((ulong)*p + gd->reloc_off);
574 static inline void malloc_bin_reloc(void) {}
577 ulong mem_malloc_start = 0;
578 ulong mem_malloc_end = 0;
579 ulong mem_malloc_brk = 0;
581 void *sbrk(ptrdiff_t increment)
583 ulong old = mem_malloc_brk;
584 ulong new = old + increment;
587 * if we are giving memory back make sure we clear it out since
588 * we set MORECORE_CLEARS to 1
591 memset((void *)new, 0, -increment);
593 if ((new < mem_malloc_start) || (new > mem_malloc_end))
594 return (void *)MORECORE_FAILURE;
596 mem_malloc_brk = new;
601 void mem_malloc_init(ulong start, ulong size)
603 mem_malloc_start = start;
604 mem_malloc_end = start + size;
605 mem_malloc_brk = start;
607 debug("using memory %#lx-%#lx for malloc()\n", mem_malloc_start,
609 #ifdef CONFIG_SYS_MALLOC_CLEAR_ON_INIT
610 memset((void *)mem_malloc_start, 0x0, size);
615 /* field-extraction macros */
617 #define first(b) ((b)->fd)
618 #define last(b) ((b)->bk)
624 #define bin_index(sz) \
625 (((((unsigned long)(sz)) >> 9) == 0) ? (((unsigned long)(sz)) >> 3): \
626 ((((unsigned long)(sz)) >> 9) <= 4) ? 56 + (((unsigned long)(sz)) >> 6): \
627 ((((unsigned long)(sz)) >> 9) <= 20) ? 91 + (((unsigned long)(sz)) >> 9): \
628 ((((unsigned long)(sz)) >> 9) <= 84) ? 110 + (((unsigned long)(sz)) >> 12): \
629 ((((unsigned long)(sz)) >> 9) <= 340) ? 119 + (((unsigned long)(sz)) >> 15): \
630 ((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18): \
633 bins for chunks < 512 are all spaced 8 bytes apart, and hold
634 identically sized chunks. This is exploited in malloc.
637 #define MAX_SMALLBIN 63
638 #define MAX_SMALLBIN_SIZE 512
639 #define SMALLBIN_WIDTH 8
641 #define smallbin_index(sz) (((unsigned long)(sz)) >> 3)
644 Requests are `small' if both the corresponding and the next bin are small
647 #define is_small_request(nb) (nb < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH)
652 To help compensate for the large number of bins, a one-level index
653 structure is used for bin-by-bin searching. `binblocks' is a
654 one-word bitvector recording whether groups of BINBLOCKWIDTH bins
655 have any (possibly) non-empty bins, so they can be skipped over
656 all at once during during traversals. The bits are NOT always
657 cleared as soon as all bins in a block are empty, but instead only
658 when all are noticed to be empty during traversal in malloc.
661 #define BINBLOCKWIDTH 4 /* bins per block */
663 #define binblocks_r ((INTERNAL_SIZE_T)av_[1]) /* bitvector of nonempty blocks */
664 #define binblocks_w (av_[1])
666 /* bin<->block macros */
668 #define idx2binblock(ix) ((unsigned)1 << (ix / BINBLOCKWIDTH))
669 #define mark_binblock(ii) (binblocks_w = (mbinptr)(binblocks_r | idx2binblock(ii)))
670 #define clear_binblock(ii) (binblocks_w = (mbinptr)(binblocks_r & ~(idx2binblock(ii))))
676 /* Other static bookkeeping data */
678 /* variables holding tunable values */
680 static unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD;
681 static unsigned long top_pad = DEFAULT_TOP_PAD;
682 static unsigned int n_mmaps_max = DEFAULT_MMAP_MAX;
683 static unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD;
685 /* The first value returned from sbrk */
686 static char* sbrk_base = (char*)(-1);
688 /* The maximum memory obtained from system via sbrk */
689 static unsigned long max_sbrked_mem = 0;
691 /* The maximum via either sbrk or mmap */
692 static unsigned long max_total_mem = 0;
694 /* internal working copy of mallinfo */
695 static struct mallinfo current_mallinfo = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
697 /* The total memory obtained from system via sbrk */
698 #define sbrked_mem (current_mallinfo.arena)
703 static unsigned int n_mmaps = 0;
705 static unsigned long mmapped_mem = 0;
707 static unsigned int max_n_mmaps = 0;
708 static unsigned long max_mmapped_mem = 0;
721 These routines make a number of assertions about the states
722 of data structures that should be true at all times. If any
723 are not true, it's very likely that a user program has somehow
724 trashed memory. (It's also possible that there is a coding error
725 in malloc. In which case, please report it!)
729 static void do_check_chunk(mchunkptr p)
731 static void do_check_chunk(p) mchunkptr p;
734 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
736 /* No checkable chunk is mmapped */
737 assert(!chunk_is_mmapped(p));
739 /* Check for legal address ... */
740 assert((char*)p >= sbrk_base);
742 assert((char*)p + sz <= (char*)top);
744 assert((char*)p + sz <= sbrk_base + sbrked_mem);
750 static void do_check_free_chunk(mchunkptr p)
752 static void do_check_free_chunk(p) mchunkptr p;
755 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
756 mchunkptr next = chunk_at_offset(p, sz);
760 /* Check whether it claims to be free ... */
763 /* Unless a special marker, must have OK fields */
764 if ((long)sz >= (long)MINSIZE)
766 assert((sz & MALLOC_ALIGN_MASK) == 0);
767 assert(aligned_OK(chunk2mem(p)));
768 /* ... matching footer field */
769 assert(next->prev_size == sz);
770 /* ... and is fully consolidated */
771 assert(prev_inuse(p));
772 assert (next == top || inuse(next));
774 /* ... and has minimally sane links */
775 assert(p->fd->bk == p);
776 assert(p->bk->fd == p);
778 else /* markers are always of size SIZE_SZ */
779 assert(sz == SIZE_SZ);
783 static void do_check_inuse_chunk(mchunkptr p)
785 static void do_check_inuse_chunk(p) mchunkptr p;
788 mchunkptr next = next_chunk(p);
791 /* Check whether it claims to be in use ... */
794 /* ... and is surrounded by OK chunks.
795 Since more things can be checked with free chunks than inuse ones,
796 if an inuse chunk borders them and debug is on, it's worth doing them.
800 mchunkptr prv = prev_chunk(p);
801 assert(next_chunk(prv) == p);
802 do_check_free_chunk(prv);
806 assert(prev_inuse(next));
807 assert(chunksize(next) >= MINSIZE);
809 else if (!inuse(next))
810 do_check_free_chunk(next);
815 static void do_check_malloced_chunk(mchunkptr p, INTERNAL_SIZE_T s)
817 static void do_check_malloced_chunk(p, s) mchunkptr p; INTERNAL_SIZE_T s;
820 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
823 do_check_inuse_chunk(p);
826 assert((long)sz >= (long)MINSIZE);
827 assert((sz & MALLOC_ALIGN_MASK) == 0);
829 assert(room < (long)MINSIZE);
831 /* ... and alignment */
832 assert(aligned_OK(chunk2mem(p)));
835 /* ... and was allocated at front of an available chunk */
836 assert(prev_inuse(p));
841 #define check_free_chunk(P) do_check_free_chunk(P)
842 #define check_inuse_chunk(P) do_check_inuse_chunk(P)
843 #define check_chunk(P) do_check_chunk(P)
844 #define check_malloced_chunk(P,N) do_check_malloced_chunk(P,N)
846 #define check_free_chunk(P)
847 #define check_inuse_chunk(P)
848 #define check_chunk(P)
849 #define check_malloced_chunk(P,N)
855 Macro-based internal utilities
860 Linking chunks in bin lists.
861 Call these only with variables, not arbitrary expressions, as arguments.
865 Place chunk p of size s in its bin, in size order,
866 putting it ahead of others of same size.
870 #define frontlink(P, S, IDX, BK, FD) \
872 if (S < MAX_SMALLBIN_SIZE) \
874 IDX = smallbin_index(S); \
875 mark_binblock(IDX); \
880 FD->bk = BK->fd = P; \
884 IDX = bin_index(S); \
887 if (FD == BK) mark_binblock(IDX); \
890 while (FD != BK && S < chunksize(FD)) FD = FD->fd; \
895 FD->bk = BK->fd = P; \
900 /* take a chunk off a list */
902 #define unlink(P, BK, FD) \
910 /* Place p as the last remainder */
912 #define link_last_remainder(P) \
914 last_remainder->fd = last_remainder->bk = P; \
915 P->fd = P->bk = last_remainder; \
918 /* Clear the last_remainder bin */
920 #define clear_last_remainder \
921 (last_remainder->fd = last_remainder->bk = last_remainder)
927 /* Routines dealing with mmap(). */
932 static mchunkptr mmap_chunk(size_t size)
934 static mchunkptr mmap_chunk(size) size_t size;
937 size_t page_mask = malloc_getpagesize - 1;
940 #ifndef MAP_ANONYMOUS
944 if(n_mmaps >= n_mmaps_max) return 0; /* too many regions */
946 /* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because
947 * there is no following chunk whose prev_size field could be used.
949 size = (size + SIZE_SZ + page_mask) & ~page_mask;
952 p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE,
953 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
954 #else /* !MAP_ANONYMOUS */
957 fd = open("/dev/zero", O_RDWR);
960 p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
963 if(p == (mchunkptr)-1) return 0;
966 if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps;
968 /* We demand that eight bytes into a page must be 8-byte aligned. */
969 assert(aligned_OK(chunk2mem(p)));
971 /* The offset to the start of the mmapped region is stored
972 * in the prev_size field of the chunk; normally it is zero,
973 * but that can be changed in memalign().
976 set_head(p, size|IS_MMAPPED);
979 if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
980 max_mmapped_mem = mmapped_mem;
981 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
982 max_total_mem = mmapped_mem + sbrked_mem;
987 static void munmap_chunk(mchunkptr p)
989 static void munmap_chunk(p) mchunkptr p;
992 INTERNAL_SIZE_T size = chunksize(p);
995 assert (chunk_is_mmapped(p));
996 assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
997 assert((n_mmaps > 0));
998 assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0);
1001 mmapped_mem -= (size + p->prev_size);
1003 ret = munmap((char *)p - p->prev_size, size + p->prev_size);
1005 /* munmap returns non-zero on failure */
1012 static mchunkptr mremap_chunk(mchunkptr p, size_t new_size)
1014 static mchunkptr mremap_chunk(p, new_size) mchunkptr p; size_t new_size;
1017 size_t page_mask = malloc_getpagesize - 1;
1018 INTERNAL_SIZE_T offset = p->prev_size;
1019 INTERNAL_SIZE_T size = chunksize(p);
1022 assert (chunk_is_mmapped(p));
1023 assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
1024 assert((n_mmaps > 0));
1025 assert(((size + offset) & (malloc_getpagesize-1)) == 0);
1027 /* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
1028 new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask;
1030 cp = (char *)mremap((char *)p - offset, size + offset, new_size, 1);
1032 if (cp == (char *)-1) return 0;
1034 p = (mchunkptr)(cp + offset);
1036 assert(aligned_OK(chunk2mem(p)));
1038 assert((p->prev_size == offset));
1039 set_head(p, (new_size - offset)|IS_MMAPPED);
1041 mmapped_mem -= size + offset;
1042 mmapped_mem += new_size;
1043 if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
1044 max_mmapped_mem = mmapped_mem;
1045 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
1046 max_total_mem = mmapped_mem + sbrked_mem;
1050 #endif /* HAVE_MREMAP */
1052 #endif /* HAVE_MMAP */
1058 Extend the top-most chunk by obtaining memory from system.
1059 Main interface to sbrk (but see also malloc_trim).
1063 static void malloc_extend_top(INTERNAL_SIZE_T nb)
1065 static void malloc_extend_top(nb) INTERNAL_SIZE_T nb;
1068 char* brk; /* return value from sbrk */
1069 INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */
1070 INTERNAL_SIZE_T correction; /* bytes for 2nd sbrk call */
1071 char* new_brk; /* return of 2nd sbrk call */
1072 INTERNAL_SIZE_T top_size; /* new size of top chunk */
1074 mchunkptr old_top = top; /* Record state of old top */
1075 INTERNAL_SIZE_T old_top_size = chunksize(old_top);
1076 char* old_end = (char*)(chunk_at_offset(old_top, old_top_size));
1078 /* Pad request with top_pad plus minimal overhead */
1080 INTERNAL_SIZE_T sbrk_size = nb + top_pad + MINSIZE;
1081 unsigned long pagesz = malloc_getpagesize;
1083 /* If not the first time through, round to preserve page boundary */
1084 /* Otherwise, we need to correct to a page size below anyway. */
1085 /* (We also correct below if an intervening foreign sbrk call.) */
1087 if (sbrk_base != (char*)(-1))
1088 sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1);
1090 brk = (char*)(MORECORE (sbrk_size));
1092 /* Fail if sbrk failed or if a foreign sbrk call killed our space */
1093 if (brk == (char*)(MORECORE_FAILURE) ||
1094 (brk < old_end && old_top != initial_top))
1097 sbrked_mem += sbrk_size;
1099 if (brk == old_end) /* can just add bytes to current top */
1101 top_size = sbrk_size + old_top_size;
1102 set_head(top, top_size | PREV_INUSE);
1106 if (sbrk_base == (char*)(-1)) /* First time through. Record base */
1108 else /* Someone else called sbrk(). Count those bytes as sbrked_mem. */
1109 sbrked_mem += brk - (char*)old_end;
1111 /* Guarantee alignment of first new chunk made from this space */
1112 front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK;
1113 if (front_misalign > 0)
1115 correction = (MALLOC_ALIGNMENT) - front_misalign;
1121 /* Guarantee the next brk will be at a page boundary */
1123 correction += ((((unsigned long)(brk + sbrk_size))+(pagesz-1)) &
1124 ~(pagesz - 1)) - ((unsigned long)(brk + sbrk_size));
1126 /* Allocate correction */
1127 new_brk = (char*)(MORECORE (correction));
1128 if (new_brk == (char*)(MORECORE_FAILURE)) return;
1130 sbrked_mem += correction;
1132 top = (mchunkptr)brk;
1133 top_size = new_brk - brk + correction;
1134 set_head(top, top_size | PREV_INUSE);
1136 if (old_top != initial_top)
1139 /* There must have been an intervening foreign sbrk call. */
1140 /* A double fencepost is necessary to prevent consolidation */
1142 /* If not enough space to do this, then user did something very wrong */
1143 if (old_top_size < MINSIZE)
1145 set_head(top, PREV_INUSE); /* will force null return from malloc */
1149 /* Also keep size a multiple of MALLOC_ALIGNMENT */
1150 old_top_size = (old_top_size - 3*SIZE_SZ) & ~MALLOC_ALIGN_MASK;
1151 set_head_size(old_top, old_top_size);
1152 chunk_at_offset(old_top, old_top_size )->size =
1154 chunk_at_offset(old_top, old_top_size + SIZE_SZ)->size =
1156 /* If possible, release the rest. */
1157 if (old_top_size >= MINSIZE)
1158 fREe(chunk2mem(old_top));
1162 if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem)
1163 max_sbrked_mem = sbrked_mem;
1164 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
1165 max_total_mem = mmapped_mem + sbrked_mem;
1167 /* We always land on a page boundary */
1168 assert(((unsigned long)((char*)top + top_size) & (pagesz - 1)) == 0);
1174 /* Main public routines */
1180 The requested size is first converted into a usable form, `nb'.
1181 This currently means to add 4 bytes overhead plus possibly more to
1182 obtain 8-byte alignment and/or to obtain a size of at least
1183 MINSIZE (currently 16 bytes), the smallest allocatable size.
1184 (All fits are considered `exact' if they are within MINSIZE bytes.)
1186 From there, the first successful of the following steps is taken:
1188 1. The bin corresponding to the request size is scanned, and if
1189 a chunk of exactly the right size is found, it is taken.
1191 2. The most recently remaindered chunk is used if it is big
1192 enough. This is a form of (roving) first fit, used only in
1193 the absence of exact fits. Runs of consecutive requests use
1194 the remainder of the chunk used for the previous such request
1195 whenever possible. This limited use of a first-fit style
1196 allocation strategy tends to give contiguous chunks
1197 coextensive lifetimes, which improves locality and can reduce
1198 fragmentation in the long run.
1200 3. Other bins are scanned in increasing size order, using a
1201 chunk big enough to fulfill the request, and splitting off
1202 any remainder. This search is strictly by best-fit; i.e.,
1203 the smallest (with ties going to approximately the least
1204 recently used) chunk that fits is selected.
1206 4. If large enough, the chunk bordering the end of memory
1207 (`top') is split off. (This use of `top' is in accord with
1208 the best-fit search rule. In effect, `top' is treated as
1209 larger (and thus less well fitting) than any other available
1210 chunk since it can be extended to be as large as necessary
1211 (up to system limitations).
1213 5. If the request size meets the mmap threshold and the
1214 system supports mmap, and there are few enough currently
1215 allocated mmapped regions, and a call to mmap succeeds,
1216 the request is allocated via direct memory mapping.
1218 6. Otherwise, the top of memory is extended by
1219 obtaining more space from the system (normally using sbrk,
1220 but definable to anything else via the MORECORE macro).
1221 Memory is gathered from the system (in system page-sized
1222 units) in a way that allows chunks obtained across different
1223 sbrk calls to be consolidated, but does not require
1224 contiguous memory. Thus, it should be safe to intersperse
1225 mallocs with other sbrk calls.
1228 All allocations are made from the the `lowest' part of any found
1229 chunk. (The implementation invariant is that prev_inuse is
1230 always true of any allocated chunk; i.e., that each allocated
1231 chunk borders either a previously allocated and still in-use chunk,
1232 or the base of its memory arena.)
1237 Void_t* mALLOc(size_t bytes)
1239 Void_t* mALLOc(bytes) size_t bytes;
1242 mchunkptr victim; /* inspected/selected chunk */
1243 INTERNAL_SIZE_T victim_size; /* its size */
1244 int idx; /* index for bin traversal */
1245 mbinptr bin; /* associated bin */
1246 mchunkptr remainder; /* remainder from a split */
1247 long remainder_size; /* its size */
1248 int remainder_index; /* its bin index */
1249 unsigned long block; /* block traverser bit */
1250 int startidx; /* first bin of a traversed block */
1251 mchunkptr fwd; /* misc temp for linking */
1252 mchunkptr bck; /* misc temp for linking */
1253 mbinptr q; /* misc temp */
1257 #if CONFIG_VAL(SYS_MALLOC_F_LEN)
1258 if (!(gd->flags & GD_FLG_FULL_MALLOC_INIT))
1259 return malloc_simple(bytes);
1262 /* check if mem_malloc_init() was run */
1263 if ((mem_malloc_start == 0) && (mem_malloc_end == 0)) {
1264 /* not initialized yet */
1268 if ((long)bytes < 0) return NULL;
1270 nb = request2size(bytes); /* padded request size; */
1272 /* Check for exact match in a bin */
1274 if (is_small_request(nb)) /* Faster version for small requests */
1276 idx = smallbin_index(nb);
1278 /* No traversal or size check necessary for small bins. */
1283 /* Also scan the next one, since it would have a remainder < MINSIZE */
1291 victim_size = chunksize(victim);
1292 unlink(victim, bck, fwd);
1293 set_inuse_bit_at_offset(victim, victim_size);
1294 check_malloced_chunk(victim, nb);
1295 return chunk2mem(victim);
1298 idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */
1303 idx = bin_index(nb);
1306 for (victim = last(bin); victim != bin; victim = victim->bk)
1308 victim_size = chunksize(victim);
1309 remainder_size = victim_size - nb;
1311 if (remainder_size >= (long)MINSIZE) /* too big */
1313 --idx; /* adjust to rescan below after checking last remainder */
1317 else if (remainder_size >= 0) /* exact fit */
1319 unlink(victim, bck, fwd);
1320 set_inuse_bit_at_offset(victim, victim_size);
1321 check_malloced_chunk(victim, nb);
1322 return chunk2mem(victim);
1330 /* Try to use the last split-off remainder */
1332 if ( (victim = last_remainder->fd) != last_remainder)
1334 victim_size = chunksize(victim);
1335 remainder_size = victim_size - nb;
1337 if (remainder_size >= (long)MINSIZE) /* re-split */
1339 remainder = chunk_at_offset(victim, nb);
1340 set_head(victim, nb | PREV_INUSE);
1341 link_last_remainder(remainder);
1342 set_head(remainder, remainder_size | PREV_INUSE);
1343 set_foot(remainder, remainder_size);
1344 check_malloced_chunk(victim, nb);
1345 return chunk2mem(victim);
1348 clear_last_remainder;
1350 if (remainder_size >= 0) /* exhaust */
1352 set_inuse_bit_at_offset(victim, victim_size);
1353 check_malloced_chunk(victim, nb);
1354 return chunk2mem(victim);
1357 /* Else place in bin */
1359 frontlink(victim, victim_size, remainder_index, bck, fwd);
1363 If there are any possibly nonempty big-enough blocks,
1364 search for best fitting chunk by scanning bins in blockwidth units.
1367 if ( (block = idx2binblock(idx)) <= binblocks_r)
1370 /* Get to the first marked block */
1372 if ( (block & binblocks_r) == 0)
1374 /* force to an even block boundary */
1375 idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH;
1377 while ((block & binblocks_r) == 0)
1379 idx += BINBLOCKWIDTH;
1384 /* For each possibly nonempty block ... */
1387 startidx = idx; /* (track incomplete blocks) */
1388 q = bin = bin_at(idx);
1390 /* For each bin in this block ... */
1393 /* Find and use first big enough chunk ... */
1395 for (victim = last(bin); victim != bin; victim = victim->bk)
1397 victim_size = chunksize(victim);
1398 remainder_size = victim_size - nb;
1400 if (remainder_size >= (long)MINSIZE) /* split */
1402 remainder = chunk_at_offset(victim, nb);
1403 set_head(victim, nb | PREV_INUSE);
1404 unlink(victim, bck, fwd);
1405 link_last_remainder(remainder);
1406 set_head(remainder, remainder_size | PREV_INUSE);
1407 set_foot(remainder, remainder_size);
1408 check_malloced_chunk(victim, nb);
1409 return chunk2mem(victim);
1412 else if (remainder_size >= 0) /* take */
1414 set_inuse_bit_at_offset(victim, victim_size);
1415 unlink(victim, bck, fwd);
1416 check_malloced_chunk(victim, nb);
1417 return chunk2mem(victim);
1422 bin = next_bin(bin);
1424 } while ((++idx & (BINBLOCKWIDTH - 1)) != 0);
1426 /* Clear out the block bit. */
1428 do /* Possibly backtrack to try to clear a partial block */
1430 if ((startidx & (BINBLOCKWIDTH - 1)) == 0)
1432 av_[1] = (mbinptr)(binblocks_r & ~block);
1437 } while (first(q) == q);
1439 /* Get to the next possibly nonempty block */
1441 if ( (block <<= 1) <= binblocks_r && (block != 0) )
1443 while ((block & binblocks_r) == 0)
1445 idx += BINBLOCKWIDTH;
1455 /* Try to use top chunk */
1457 /* Require that there be a remainder, ensuring top always exists */
1458 if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE)
1462 /* If big and would otherwise need to extend, try to use mmap instead */
1463 if ((unsigned long)nb >= (unsigned long)mmap_threshold &&
1464 (victim = mmap_chunk(nb)))
1465 return chunk2mem(victim);
1469 malloc_extend_top(nb);
1470 if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE)
1471 return NULL; /* propagate failure */
1475 set_head(victim, nb | PREV_INUSE);
1476 top = chunk_at_offset(victim, nb);
1477 set_head(top, remainder_size | PREV_INUSE);
1478 check_malloced_chunk(victim, nb);
1479 return chunk2mem(victim);
1492 1. free(0) has no effect.
1494 2. If the chunk was allocated via mmap, it is release via munmap().
1496 3. If a returned chunk borders the current high end of memory,
1497 it is consolidated into the top, and if the total unused
1498 topmost memory exceeds the trim threshold, malloc_trim is
1501 4. Other chunks are consolidated as they arrive, and
1502 placed in corresponding bins. (This includes the case of
1503 consolidating with the current `last_remainder').
1509 void fREe(Void_t* mem)
1511 void fREe(mem) Void_t* mem;
1514 mchunkptr p; /* chunk corresponding to mem */
1515 INTERNAL_SIZE_T hd; /* its head field */
1516 INTERNAL_SIZE_T sz; /* its size */
1517 int idx; /* its bin index */
1518 mchunkptr next; /* next contiguous chunk */
1519 INTERNAL_SIZE_T nextsz; /* its size */
1520 INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */
1521 mchunkptr bck; /* misc temp for linking */
1522 mchunkptr fwd; /* misc temp for linking */
1523 int islr; /* track whether merging with last_remainder */
1525 #if CONFIG_VAL(SYS_MALLOC_F_LEN)
1526 /* free() is a no-op - all the memory will be freed on relocation */
1527 if (!(gd->flags & GD_FLG_FULL_MALLOC_INIT))
1531 if (mem == NULL) /* free(0) has no effect */
1538 if (hd & IS_MMAPPED) /* release mmapped memory. */
1545 check_inuse_chunk(p);
1547 sz = hd & ~PREV_INUSE;
1548 next = chunk_at_offset(p, sz);
1549 nextsz = chunksize(next);
1551 if (next == top) /* merge with top */
1555 if (!(hd & PREV_INUSE)) /* consolidate backward */
1557 prevsz = p->prev_size;
1558 p = chunk_at_offset(p, -((long) prevsz));
1560 unlink(p, bck, fwd);
1563 set_head(p, sz | PREV_INUSE);
1565 if ((unsigned long)(sz) >= (unsigned long)trim_threshold)
1566 malloc_trim(top_pad);
1570 set_head(next, nextsz); /* clear inuse bit */
1574 if (!(hd & PREV_INUSE)) /* consolidate backward */
1576 prevsz = p->prev_size;
1577 p = chunk_at_offset(p, -((long) prevsz));
1580 if (p->fd == last_remainder) /* keep as last_remainder */
1583 unlink(p, bck, fwd);
1586 if (!(inuse_bit_at_offset(next, nextsz))) /* consolidate forward */
1590 if (!islr && next->fd == last_remainder) /* re-insert last_remainder */
1593 link_last_remainder(p);
1596 unlink(next, bck, fwd);
1600 set_head(p, sz | PREV_INUSE);
1603 frontlink(p, sz, idx, bck, fwd);
1614 Chunks that were obtained via mmap cannot be extended or shrunk
1615 unless HAVE_MREMAP is defined, in which case mremap is used.
1616 Otherwise, if their reallocation is for additional space, they are
1617 copied. If for less, they are just left alone.
1619 Otherwise, if the reallocation is for additional space, and the
1620 chunk can be extended, it is, else a malloc-copy-free sequence is
1621 taken. There are several different ways that a chunk could be
1622 extended. All are tried:
1624 * Extending forward into following adjacent free chunk.
1625 * Shifting backwards, joining preceding adjacent space
1626 * Both shifting backwards and extending forward.
1627 * Extending into newly sbrked space
1629 Unless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with a
1630 size argument of zero (re)allocates a minimum-sized chunk.
1632 If the reallocation is for less space, and the new request is for
1633 a `small' (<512 bytes) size, then the newly unused space is lopped
1636 The old unix realloc convention of allowing the last-free'd chunk
1637 to be used as an argument to realloc is no longer supported.
1638 I don't know of any programs still relying on this feature,
1639 and allowing it would also allow too many other incorrect
1640 usages of realloc to be sensible.
1647 Void_t* rEALLOc(Void_t* oldmem, size_t bytes)
1649 Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes;
1652 INTERNAL_SIZE_T nb; /* padded request size */
1654 mchunkptr oldp; /* chunk corresponding to oldmem */
1655 INTERNAL_SIZE_T oldsize; /* its size */
1657 mchunkptr newp; /* chunk to return */
1658 INTERNAL_SIZE_T newsize; /* its size */
1659 Void_t* newmem; /* corresponding user mem */
1661 mchunkptr next; /* next contiguous chunk after oldp */
1662 INTERNAL_SIZE_T nextsize; /* its size */
1664 mchunkptr prev; /* previous contiguous chunk before oldp */
1665 INTERNAL_SIZE_T prevsize; /* its size */
1667 mchunkptr remainder; /* holds split off extra space from newp */
1668 INTERNAL_SIZE_T remainder_size; /* its size */
1670 mchunkptr bck; /* misc temp for linking */
1671 mchunkptr fwd; /* misc temp for linking */
1673 #ifdef REALLOC_ZERO_BYTES_FREES
1680 if ((long)bytes < 0) return NULL;
1682 /* realloc of null is supposed to be same as malloc */
1683 if (oldmem == NULL) return mALLOc(bytes);
1685 #if CONFIG_VAL(SYS_MALLOC_F_LEN)
1686 if (!(gd->flags & GD_FLG_FULL_MALLOC_INIT)) {
1687 /* This is harder to support and should not be needed */
1688 panic("pre-reloc realloc() is not supported");
1692 newp = oldp = mem2chunk(oldmem);
1693 newsize = oldsize = chunksize(oldp);
1696 nb = request2size(bytes);
1699 if (chunk_is_mmapped(oldp))
1702 newp = mremap_chunk(oldp, nb);
1703 if(newp) return chunk2mem(newp);
1705 /* Note the extra SIZE_SZ overhead. */
1706 if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing */
1707 /* Must alloc, copy, free. */
1708 newmem = mALLOc(bytes);
1710 return NULL; /* propagate failure */
1711 MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ);
1717 check_inuse_chunk(oldp);
1719 if ((long)(oldsize) < (long)(nb))
1722 /* Try expanding forward */
1724 next = chunk_at_offset(oldp, oldsize);
1725 if (next == top || !inuse(next))
1727 nextsize = chunksize(next);
1729 /* Forward into top only if a remainder */
1732 if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE))
1734 newsize += nextsize;
1735 top = chunk_at_offset(oldp, nb);
1736 set_head(top, (newsize - nb) | PREV_INUSE);
1737 set_head_size(oldp, nb);
1738 return chunk2mem(oldp);
1742 /* Forward into next chunk */
1743 else if (((long)(nextsize + newsize) >= (long)(nb)))
1745 unlink(next, bck, fwd);
1746 newsize += nextsize;
1756 /* Try shifting backwards. */
1758 if (!prev_inuse(oldp))
1760 prev = prev_chunk(oldp);
1761 prevsize = chunksize(prev);
1763 /* try forward + backward first to save a later consolidation */
1770 if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE))
1772 unlink(prev, bck, fwd);
1774 newsize += prevsize + nextsize;
1775 newmem = chunk2mem(newp);
1776 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
1777 top = chunk_at_offset(newp, nb);
1778 set_head(top, (newsize - nb) | PREV_INUSE);
1779 set_head_size(newp, nb);
1784 /* into next chunk */
1785 else if (((long)(nextsize + prevsize + newsize) >= (long)(nb)))
1787 unlink(next, bck, fwd);
1788 unlink(prev, bck, fwd);
1790 newsize += nextsize + prevsize;
1791 newmem = chunk2mem(newp);
1792 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
1798 if (prev != NULL && (long)(prevsize + newsize) >= (long)nb)
1800 unlink(prev, bck, fwd);
1802 newsize += prevsize;
1803 newmem = chunk2mem(newp);
1804 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
1811 newmem = mALLOc (bytes);
1813 if (newmem == NULL) /* propagate failure */
1816 /* Avoid copy if newp is next chunk after oldp. */
1817 /* (This can only happen when new chunk is sbrk'ed.) */
1819 if ( (newp = mem2chunk(newmem)) == next_chunk(oldp))
1821 newsize += chunksize(newp);
1826 /* Otherwise copy, free, and exit */
1827 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
1833 split: /* split off extra room in old or expanded chunk */
1835 if (newsize - nb >= MINSIZE) /* split off remainder */
1837 remainder = chunk_at_offset(newp, nb);
1838 remainder_size = newsize - nb;
1839 set_head_size(newp, nb);
1840 set_head(remainder, remainder_size | PREV_INUSE);
1841 set_inuse_bit_at_offset(remainder, remainder_size);
1842 fREe(chunk2mem(remainder)); /* let free() deal with it */
1846 set_head_size(newp, newsize);
1847 set_inuse_bit_at_offset(newp, newsize);
1850 check_inuse_chunk(newp);
1851 return chunk2mem(newp);
1861 memalign requests more than enough space from malloc, finds a spot
1862 within that chunk that meets the alignment request, and then
1863 possibly frees the leading and trailing space.
1865 The alignment argument must be a power of two. This property is not
1866 checked by memalign, so misuse may result in random runtime errors.
1868 8-byte alignment is guaranteed by normal malloc calls, so don't
1869 bother calling memalign with an argument of 8 or less.
1871 Overreliance on memalign is a sure way to fragment space.
1877 Void_t* mEMALIGn(size_t alignment, size_t bytes)
1879 Void_t* mEMALIGn(alignment, bytes) size_t alignment; size_t bytes;
1882 INTERNAL_SIZE_T nb; /* padded request size */
1883 char* m; /* memory returned by malloc call */
1884 mchunkptr p; /* corresponding chunk */
1885 char* brk; /* alignment point within p */
1886 mchunkptr newp; /* chunk to return */
1887 INTERNAL_SIZE_T newsize; /* its size */
1888 INTERNAL_SIZE_T leadsize; /* leading space befor alignment point */
1889 mchunkptr remainder; /* spare room at end to split off */
1890 long remainder_size; /* its size */
1892 if ((long)bytes < 0) return NULL;
1894 /* If need less alignment than we give anyway, just relay to malloc */
1896 if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes);
1898 /* Otherwise, ensure that it is at least a minimum chunk size */
1900 if (alignment < MINSIZE) alignment = MINSIZE;
1902 /* Call malloc with worst case padding to hit alignment. */
1904 nb = request2size(bytes);
1905 m = (char*)(mALLOc(nb + alignment + MINSIZE));
1908 * The attempt to over-allocate (with a size large enough to guarantee the
1909 * ability to find an aligned region within allocated memory) failed.
1911 * Try again, this time only allocating exactly the size the user wants. If
1912 * the allocation now succeeds and just happens to be aligned, we can still
1913 * fulfill the user's request.
1916 size_t extra, extra2;
1918 * Use bytes not nb, since mALLOc internally calls request2size too, and
1919 * each call increases the size to allocate, to account for the header.
1921 m = (char*)(mALLOc(bytes));
1922 /* Aligned -> return it */
1923 if ((((unsigned long)(m)) % alignment) == 0)
1926 * Otherwise, try again, requesting enough extra space to be able to
1927 * acquire alignment.
1930 /* Add in extra bytes to match misalignment of unexpanded allocation */
1931 extra = alignment - (((unsigned long)(m)) % alignment);
1932 m = (char*)(mALLOc(bytes + extra));
1934 * m might not be the same as before. Validate that the previous value of
1935 * extra still works for the current value of m.
1936 * If (!m), extra2=alignment so
1939 extra2 = alignment - (((unsigned long)(m)) % alignment);
1940 if (extra2 > extra) {
1945 /* Fall through to original NULL check and chunk splitting logic */
1948 if (m == NULL) return NULL; /* propagate failure */
1952 if ((((unsigned long)(m)) % alignment) == 0) /* aligned */
1955 if(chunk_is_mmapped(p))
1956 return chunk2mem(p); /* nothing more to do */
1959 else /* misaligned */
1962 Find an aligned spot inside chunk.
1963 Since we need to give back leading space in a chunk of at
1964 least MINSIZE, if the first calculation places us at
1965 a spot with less than MINSIZE leader, we can move to the
1966 next aligned spot -- we've allocated enough total room so that
1967 this is always possible.
1970 brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) & -((signed) alignment));
1971 if ((long)(brk - (char*)(p)) < MINSIZE) brk = brk + alignment;
1973 newp = (mchunkptr)brk;
1974 leadsize = brk - (char*)(p);
1975 newsize = chunksize(p) - leadsize;
1978 if(chunk_is_mmapped(p))
1980 newp->prev_size = p->prev_size + leadsize;
1981 set_head(newp, newsize|IS_MMAPPED);
1982 return chunk2mem(newp);
1986 /* give back leader, use the rest */
1988 set_head(newp, newsize | PREV_INUSE);
1989 set_inuse_bit_at_offset(newp, newsize);
1990 set_head_size(p, leadsize);
1994 assert (newsize >= nb && (((unsigned long)(chunk2mem(p))) % alignment) == 0);
1997 /* Also give back spare room at the end */
1999 remainder_size = chunksize(p) - nb;
2001 if (remainder_size >= (long)MINSIZE)
2003 remainder = chunk_at_offset(p, nb);
2004 set_head(remainder, remainder_size | PREV_INUSE);
2005 set_head_size(p, nb);
2006 fREe(chunk2mem(remainder));
2009 check_inuse_chunk(p);
2010 return chunk2mem(p);
2018 valloc just invokes memalign with alignment argument equal
2019 to the page size of the system (or as near to this as can
2020 be figured out from all the includes/defines above.)
2024 Void_t* vALLOc(size_t bytes)
2026 Void_t* vALLOc(bytes) size_t bytes;
2029 return mEMALIGn (malloc_getpagesize, bytes);
2033 pvalloc just invokes valloc for the nearest pagesize
2034 that will accommodate request
2039 Void_t* pvALLOc(size_t bytes)
2041 Void_t* pvALLOc(bytes) size_t bytes;
2044 size_t pagesize = malloc_getpagesize;
2045 return mEMALIGn (pagesize, (bytes + pagesize - 1) & ~(pagesize - 1));
2050 calloc calls malloc, then zeroes out the allocated chunk.
2055 Void_t* cALLOc(size_t n, size_t elem_size)
2057 Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size;
2061 INTERNAL_SIZE_T csz;
2063 INTERNAL_SIZE_T sz = n * elem_size;
2066 /* check if expand_top called, in which case don't need to clear */
2067 #ifdef CONFIG_SYS_MALLOC_CLEAR_ON_INIT
2069 mchunkptr oldtop = top;
2070 INTERNAL_SIZE_T oldtopsize = chunksize(top);
2073 Void_t* mem = mALLOc (sz);
2075 if ((long)n < 0) return NULL;
2081 #if CONFIG_VAL(SYS_MALLOC_F_LEN)
2082 if (!(gd->flags & GD_FLG_FULL_MALLOC_INIT)) {
2083 MALLOC_ZERO(mem, sz);
2089 /* Two optional cases in which clearing not necessary */
2093 if (chunk_is_mmapped(p)) return mem;
2098 #ifdef CONFIG_SYS_MALLOC_CLEAR_ON_INIT
2100 if (p == oldtop && csz > oldtopsize)
2102 /* clear only the bytes from non-freshly-sbrked memory */
2108 MALLOC_ZERO(mem, csz - SIZE_SZ);
2115 cfree just calls free. It is needed/defined on some systems
2116 that pair it with calloc, presumably for odd historical reasons.
2120 #if !defined(INTERNAL_LINUX_C_LIB) || !defined(__ELF__)
2122 void cfree(Void_t *mem)
2124 void cfree(mem) Void_t *mem;
2135 Malloc_trim gives memory back to the system (via negative
2136 arguments to sbrk) if there is unused memory at the `high' end of
2137 the malloc pool. You can call this after freeing large blocks of
2138 memory to potentially reduce the system-level memory requirements
2139 of a program. However, it cannot guarantee to reduce memory. Under
2140 some allocation patterns, some large free blocks of memory will be
2141 locked between two used chunks, so they cannot be given back to
2144 The `pad' argument to malloc_trim represents the amount of free
2145 trailing space to leave untrimmed. If this argument is zero,
2146 only the minimum amount of memory to maintain internal data
2147 structures will be left (one page or less). Non-zero arguments
2148 can be supplied to maintain enough trailing space to service
2149 future expected allocations without having to re-obtain memory
2152 Malloc_trim returns 1 if it actually released any memory, else 0.
2157 int malloc_trim(size_t pad)
2159 int malloc_trim(pad) size_t pad;
2162 long top_size; /* Amount of top-most memory */
2163 long extra; /* Amount to release */
2164 char* current_brk; /* address returned by pre-check sbrk call */
2165 char* new_brk; /* address returned by negative sbrk call */
2167 unsigned long pagesz = malloc_getpagesize;
2169 top_size = chunksize(top);
2170 extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz;
2172 if (extra < (long)pagesz) /* Not enough memory to release */
2177 /* Test to make sure no one else called sbrk */
2178 current_brk = (char*)(MORECORE (0));
2179 if (current_brk != (char*)(top) + top_size)
2180 return 0; /* Apparently we don't own memory; must fail */
2184 new_brk = (char*)(MORECORE (-extra));
2186 if (new_brk == (char*)(MORECORE_FAILURE)) /* sbrk failed? */
2188 /* Try to figure out what we have */
2189 current_brk = (char*)(MORECORE (0));
2190 top_size = current_brk - (char*)top;
2191 if (top_size >= (long)MINSIZE) /* if not, we are very very dead! */
2193 sbrked_mem = current_brk - sbrk_base;
2194 set_head(top, top_size | PREV_INUSE);
2202 /* Success. Adjust top accordingly. */
2203 set_head(top, (top_size - extra) | PREV_INUSE);
2204 sbrked_mem -= extra;
2217 This routine tells you how many bytes you can actually use in an
2218 allocated chunk, which may be more than you requested (although
2219 often not). You can use this many bytes without worrying about
2220 overwriting other allocated objects. Not a particularly great
2221 programming practice, but still sometimes useful.
2226 size_t malloc_usable_size(Void_t* mem)
2228 size_t malloc_usable_size(mem) Void_t* mem;
2237 if(!chunk_is_mmapped(p))
2239 if (!inuse(p)) return 0;
2240 check_inuse_chunk(p);
2241 return chunksize(p) - SIZE_SZ;
2243 return chunksize(p) - 2*SIZE_SZ;
2250 /* Utility to update current_mallinfo for malloc_stats and mallinfo() */
2253 static void malloc_update_mallinfo()
2262 INTERNAL_SIZE_T avail = chunksize(top);
2263 int navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0;
2265 for (i = 1; i < NAV; ++i)
2268 for (p = last(b); p != b; p = p->bk)
2271 check_free_chunk(p);
2272 for (q = next_chunk(p);
2273 q < top && inuse(q) && (long)(chunksize(q)) >= (long)MINSIZE;
2275 check_inuse_chunk(q);
2277 avail += chunksize(p);
2282 current_mallinfo.ordblks = navail;
2283 current_mallinfo.uordblks = sbrked_mem - avail;
2284 current_mallinfo.fordblks = avail;
2285 current_mallinfo.hblks = n_mmaps;
2286 current_mallinfo.hblkhd = mmapped_mem;
2287 current_mallinfo.keepcost = chunksize(top);
2298 Prints on the amount of space obtain from the system (both
2299 via sbrk and mmap), the maximum amount (which may be more than
2300 current if malloc_trim and/or munmap got called), the maximum
2301 number of simultaneous mmap regions used, and the current number
2302 of bytes allocated via malloc (or realloc, etc) but not yet
2303 freed. (Note that this is the number of bytes allocated, not the
2304 number requested. It will be larger than the number requested
2305 because of alignment and bookkeeping overhead.)
2312 malloc_update_mallinfo();
2313 printf("max system bytes = %10u\n",
2314 (unsigned int)(max_total_mem));
2315 printf("system bytes = %10u\n",
2316 (unsigned int)(sbrked_mem + mmapped_mem));
2317 printf("in use bytes = %10u\n",
2318 (unsigned int)(current_mallinfo.uordblks + mmapped_mem));
2320 printf("max mmap regions = %10u\n",
2321 (unsigned int)max_n_mmaps);
2327 mallinfo returns a copy of updated current mallinfo.
2331 struct mallinfo mALLINFo()
2333 malloc_update_mallinfo();
2334 return current_mallinfo;
2344 mallopt is the general SVID/XPG interface to tunable parameters.
2345 The format is to provide a (parameter-number, parameter-value) pair.
2346 mallopt then sets the corresponding parameter to the argument
2347 value if it can (i.e., so long as the value is meaningful),
2348 and returns 1 if successful else 0.
2350 See descriptions of tunable parameters above.
2355 int mALLOPt(int param_number, int value)
2357 int mALLOPt(param_number, value) int param_number; int value;
2360 switch(param_number)
2362 case M_TRIM_THRESHOLD:
2363 trim_threshold = value; return 1;
2365 top_pad = value; return 1;
2366 case M_MMAP_THRESHOLD:
2367 mmap_threshold = value; return 1;
2370 n_mmaps_max = value; return 1;
2372 if (value != 0) return 0; else n_mmaps_max = value; return 1;
2380 int initf_malloc(void)
2382 #if CONFIG_VAL(SYS_MALLOC_F_LEN)
2383 assert(gd->malloc_base); /* Set up by crt0.S */
2384 gd->malloc_limit = CONFIG_VAL(SYS_MALLOC_F_LEN);
2395 V2.6.6 Sun Dec 5 07:42:19 1999 Doug Lea (dl at gee)
2396 * return null for negative arguments
2397 * Added Several WIN32 cleanups from Martin C. Fong <mcfong@yahoo.com>
2398 * Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h'
2399 (e.g. WIN32 platforms)
2400 * Cleanup up header file inclusion for WIN32 platforms
2401 * Cleanup code to avoid Microsoft Visual C++ compiler complaints
2402 * Add 'USE_DL_PREFIX' to quickly allow co-existence with existing
2403 memory allocation routines
2404 * Set 'malloc_getpagesize' for WIN32 platforms (needs more work)
2405 * Use 'assert' rather than 'ASSERT' in WIN32 code to conform to
2406 usage of 'assert' in non-WIN32 code
2407 * Improve WIN32 'sbrk()' emulation's 'findRegion()' routine to
2409 * Always call 'fREe()' rather than 'free()'
2411 V2.6.5 Wed Jun 17 15:57:31 1998 Doug Lea (dl at gee)
2412 * Fixed ordering problem with boundary-stamping
2414 V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee)
2415 * Added pvalloc, as recommended by H.J. Liu
2416 * Added 64bit pointer support mainly from Wolfram Gloger
2417 * Added anonymously donated WIN32 sbrk emulation
2418 * Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen
2419 * malloc_extend_top: fix mask error that caused wastage after
2421 * Add linux mremap support code from HJ Liu
2423 V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee)
2424 * Integrated most documentation with the code.
2425 * Add support for mmap, with help from
2426 Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
2427 * Use last_remainder in more cases.
2428 * Pack bins using idea from colin@nyx10.cs.du.edu
2429 * Use ordered bins instead of best-fit threshhold
2430 * Eliminate block-local decls to simplify tracing and debugging.
2431 * Support another case of realloc via move into top
2432 * Fix error occuring when initial sbrk_base not word-aligned.
2433 * Rely on page size for units instead of SBRK_UNIT to
2434 avoid surprises about sbrk alignment conventions.
2435 * Add mallinfo, mallopt. Thanks to Raymond Nijssen
2436 (raymond@es.ele.tue.nl) for the suggestion.
2437 * Add `pad' argument to malloc_trim and top_pad mallopt parameter.
2438 * More precautions for cases where other routines call sbrk,
2439 courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
2440 * Added macros etc., allowing use in linux libc from
2441 H.J. Lu (hjl@gnu.ai.mit.edu)
2442 * Inverted this history list
2444 V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee)
2445 * Re-tuned and fixed to behave more nicely with V2.6.0 changes.
2446 * Removed all preallocation code since under current scheme
2447 the work required to undo bad preallocations exceeds
2448 the work saved in good cases for most test programs.
2449 * No longer use return list or unconsolidated bins since
2450 no scheme using them consistently outperforms those that don't
2451 given above changes.
2452 * Use best fit for very large chunks to prevent some worst-cases.
2453 * Added some support for debugging
2455 V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee)
2456 * Removed footers when chunks are in use. Thanks to
2457 Paul Wilson (wilson@cs.texas.edu) for the suggestion.
2459 V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee)
2460 * Added malloc_trim, with help from Wolfram Gloger
2461 (wmglo@Dent.MED.Uni-Muenchen.DE).
2463 V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g)
2465 V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g)
2466 * realloc: try to expand in both directions
2467 * malloc: swap order of clean-bin strategy;
2468 * realloc: only conditionally expand backwards
2469 * Try not to scavenge used bins
2470 * Use bin counts as a guide to preallocation
2471 * Occasionally bin return list chunks in first scan
2472 * Add a few optimizations from colin@nyx10.cs.du.edu
2474 V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g)
2475 * faster bin computation & slightly different binning
2476 * merged all consolidations to one part of malloc proper
2477 (eliminating old malloc_find_space & malloc_clean_bin)
2478 * Scan 2 returns chunks (not just 1)
2479 * Propagate failure in realloc if malloc returns 0
2480 * Add stuff to allow compilation on non-ANSI compilers
2481 from kpv@research.att.com
2483 V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu)
2484 * removed potential for odd address access in prev_chunk
2485 * removed dependency on getpagesize.h
2486 * misc cosmetics and a bit more internal documentation
2487 * anticosmetics: mangled names in macros to evade debugger strangeness
2488 * tested on sparc, hp-700, dec-mips, rs6000
2489 with gcc & native cc (hp, dec only) allowing
2490 Detlefs & Zorn comparison study (in SIGPLAN Notices.)
2492 Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu)
2493 * Based loosely on libg++-1.2X malloc. (It retains some of the overall
2494 structure of old version, but most details differ.)