malloc.c source code [glibc/malloc/malloc.c]

1	/ Malloc implementation for multiple threads without lock contention.*
2	Copyright (C) 1996-2017 Free Software Foundation, Inc.
3	This file is part of the GNU C Library.
4	Contributed by Wolfram Gloger <wg@malloc.de>
5	and Doug Lea <dl@cs.oswego.edu>, 2001.
6
7	The GNU C Library is free software; you can redistribute it and/or
8	modify it under the terms of the GNU Lesser General Public License as
9	published by the Free Software Foundation; either version 2.1 of the
10	License, or (at your option) any later version.
11
12	The GNU C Library is distributed in the hope that it will be useful,
13	but WITHOUT ANY WARRANTY; without even the implied warranty of
14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15	Lesser General Public License for more details.
16
17	You should have received a copy of the GNU Lesser General Public
18	License along with the GNU C Library; see the file COPYING.LIB. If
19	not, see <http://www.gnu.org/licenses/>. /*
20
21	/*
22	This is a version (aka ptmalloc2) of malloc/free/realloc written by
23	Doug Lea and adapted to multiple threads/arenas by Wolfram Gloger.
24
25	There have been substantial changes made after the integration into
26	glibc in all parts of the code. Do not look for much commonality
27	with the ptmalloc2 version.
28
29	* Version ptmalloc2-20011215
30	based on:
31	VERSION 2.7.0 Sun Mar 11 14:14:06 2001 Doug Lea (dl at gee)
32
33	* Quickstart
34
35	In order to compile this implementation, a Makefile is provided with
36	the ptmalloc2 distribution, which has pre-defined targets for some
37	popular systems (e.g. "make posix" for Posix threads). All that is
38	typically required with regard to compiler flags is the selection of
39	the thread package via defining one out of USE_PTHREADS, USE_THR or
40	USE_SPROC. Check the thread-m.h file for what effects this has.
41	Many/most systems will additionally require USE_TSD_DATA_HACK to be
42	defined, so this is the default for "make posix".
43
44	* Why use this malloc?
45
46	This is not the fastest, most space-conserving, most portable, or
47	most tunable malloc ever written. However it is among the fastest
48	while also being among the most space-conserving, portable and tunable.
49	Consistent balance across these factors results in a good general-purpose
50	allocator for malloc-intensive programs.
51
52	The main properties of the algorithms are:
53	* For large (>= 512 bytes) requests, it is a pure best-fit allocator,
54	with ties normally decided via FIFO (i.e. least recently used).
55	* For small (<= 64 bytes by default) requests, it is a caching
56	allocator, that maintains pools of quickly recycled chunks.
57	* In between, and for combinations of large and small requests, it does
58	the best it can trying to meet both goals at once.
59	* For very large requests (>= 128KB by default), it relies on system
60	memory mapping facilities, if supported.
61
62	For a longer but slightly out of date high-level description, see
63	http://gee.cs.oswego.edu/dl/html/malloc.html
64
65	You may already by default be using a C library containing a malloc
66	that is based on some version of this malloc (for example in
67	linux). You might still want to use the one in this file in order to
68	customize settings or to avoid overheads associated with library
69	versions.
70
71	* Contents, described in more detail in "description of public routines" below.
72
73	Standard (ANSI/SVID/...) functions:
74	malloc(size_t n);
75	calloc(size_t n_elements, size_t element_size);
76	free(void p);*
77	realloc(void p, size_t n);*
78	memalign(size_t alignment, size_t n);
79	valloc(size_t n);
80	mallinfo()
81	mallopt(int parameter_number, int parameter_value)
82
83	Additional functions:
84	independent_calloc(size_t n_elements, size_t size, void chunks[]);*
85	independent_comalloc(size_t n_elements, size_t sizes[], void chunks[]);*
86	pvalloc(size_t n);
87	malloc_trim(size_t pad);
88	malloc_usable_size(void p);*
89	malloc_stats();
90
91	* Vital statistics:
92
93	Supported pointer representation: 4 or 8 bytes
94	Supported size_t representation: 4 or 8 bytes
95	Note that size_t is allowed to be 4 bytes even if pointers are 8.
96	You can adjust this by defining INTERNAL_SIZE_T
97
98	Alignment: 2 sizeof(size_t) (default)*
99	(i.e., 8 byte alignment with 4byte size_t). This suffices for
100	nearly all current machines and C compilers. However, you can
101	define MALLOC_ALIGNMENT to be wider than this if necessary.
102
103	Minimum overhead per allocated chunk: 4 or 8 bytes
104	Each malloced chunk has a hidden word of overhead holding size
105	and status information.
106
107	Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
108	8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
109
110	When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
111	ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
112	needed; 4 (8) for a trailing size field and 8 (16) bytes for
113	free list pointers. Thus, the minimum allocatable size is
114	16/24/32 bytes.
115
116	Even a request for zero bytes (i.e., malloc(0)) returns a
117	pointer to something of the minimum allocatable size.
118
119	The maximum overhead wastage (i.e., number of extra bytes
120	allocated than were requested in malloc) is less than or equal
121	to the minimum size, except for requests >= mmap_threshold that
122	are serviced via mmap(), where the worst case wastage is 2 *
123	sizeof(size_t) bytes plus the remainder from a system page (the
124	minimal mmap unit); typically 4096 or 8192 bytes.
125
126	Maximum allocated size: 4-byte size_t: 2^32 minus about two pages
127	8-byte size_t: 2^64 minus about two pages
128
129	It is assumed that (possibly signed) size_t values suffice to
130	represent chunk sizes. `Possibly signed' is due to the fact
131	that `size_t' may be defined on a system as either a signed or
132	an unsigned type. The ISO C standard says that it must be
133	unsigned, but a few systems are known not to adhere to this.
134	Additionally, even when size_t is unsigned, sbrk (which is by
135	default used to obtain memory from system) accepts signed
136	arguments, and may not be able to handle size_t-wide arguments
137	with negative sign bit. Generally, values that would
138	appear as negative after accounting for overhead and alignment
139	are supported only via mmap(), which does not have this
140	limitation.
141
142	Requests for sizes outside the allowed range will perform an optional
143	failure action and then return null. (Requests may also
144	also fail because a system is out of memory.)
145
146	Thread-safety: thread-safe
147
148	Compliance: I believe it is compliant with the 1997 Single Unix Specification
149	Also SVID/XPG, ANSI C, and probably others as well.
150
151	* Synopsis of compile-time options:
152
153	People have reported using previous versions of this malloc on all
154	versions of Unix, sometimes by tweaking some of the defines
155	below. It has been tested most extensively on Solaris and Linux.
156	People also report using it in stand-alone embedded systems.
157
158	The implementation is in straight, hand-tuned ANSI C. It is not
159	at all modular. (Sorry!) It uses a lot of macros. To be at all
160	usable, this code should be compiled using an optimizing compiler
161	(for example gcc -O3) that can simplify expressions and control
162	paths. (FAQ: some macros import variables as arguments rather than
163	declare locals because people reported that some debuggers
164	otherwise get confused.)
165
166	OPTION DEFAULT VALUE
167
168	Compilation Environment options:
169
170	HAVE_MREMAP 0
171
172	Changing default word sizes:
173
174	INTERNAL_SIZE_T size_t
175
176	Configuration and functionality options:
177
178	USE_PUBLIC_MALLOC_WRAPPERS NOT defined
179	USE_MALLOC_LOCK NOT defined
180	MALLOC_DEBUG NOT defined
181	REALLOC_ZERO_BYTES_FREES 1
182	TRIM_FASTBINS 0
183
184	Options for customizing MORECORE:
185
186	MORECORE sbrk
187	MORECORE_FAILURE -1
188	MORECORE_CONTIGUOUS 1
189	MORECORE_CANNOT_TRIM NOT defined
190	MORECORE_CLEARS 1
191	MMAP_AS_MORECORE_SIZE (1024 1024)*
192
193	Tuning options that are also dynamically changeable via mallopt:
194
195	DEFAULT_MXFAST 64 (for 32bit), 128 (for 64bit)
196	DEFAULT_TRIM_THRESHOLD 128 1024*
197	DEFAULT_TOP_PAD 0
198	DEFAULT_MMAP_THRESHOLD 128 1024*
199	DEFAULT_MMAP_MAX 65536
200
201	There are several other #defined constants and macros that you
202	probably don't want to touch unless you are extending or adapting malloc. /*
203
204	/*
205	void is the pointer type that malloc should say it returns*
206	*/
207
208	#ifndef void
209	#define void void
210	#endif /void/
211
212	#include <stddef.h> /* for size_t */
213	#include <stdlib.h> /* for getenv(), abort() */
214	#include <unistd.h> /* for __libc_enable_secure */
215
216	#include <atomic.h>
217	#include <_itoa.h>
218	#include <bits/wordsize.h>
219	#include <sys/sysinfo.h>
220
221	#include <ldsodefs.h>
222
223	#include <unistd.h>
224	#include <stdio.h> /* needed for malloc_stats */
225	#include <errno.h>
226
227	#include <shlib-compat.h>
228
229	/ For uintptr_t. /
230	#include <stdint.h>
231
232	/ For va_arg, va_start, va_end. /
233	#include <stdarg.h>
234
235	/ For MIN, MAX, powerof2. /
236	#include <sys/param.h>
237
238	/ For ALIGN_UP et. al. /
239	#include <libc-pointer-arith.h>
240
241	/ For DIAG_PUSH/POP_NEEDS_COMMENT et al. /
242	#include <libc-diag.h>
243
244	#include <malloc/malloc-internal.h>
245
246	/*
247	Debugging:
248
249	Because freed chunks may be overwritten with bookkeeping fields, this
250	malloc will often die when freed memory is overwritten by user
251	programs. This can be very effective (albeit in an annoying way)
252	in helping track down dangling pointers.
253
254	If you compile with -DMALLOC_DEBUG, a number of assertion checks are
255	enabled that will catch more memory errors. You probably won't be
256	able to make much sense of the actual assertion errors, but they
257	should help you locate incorrectly overwritten memory. The checking
258	is fairly extensive, and will slow down execution
259	noticeably. Calling malloc_stats or mallinfo with MALLOC_DEBUG set
260	will attempt to check every non-mmapped allocated and free chunk in
261	the course of computing the summmaries. (By nature, mmapped regions
262	cannot be checked very much automatically.)
263
264	Setting MALLOC_DEBUG may also be helpful if you are trying to modify
265	this code. The assertions in the check routines spell out in more
266	detail the assumptions and invariants underlying the algorithms.
267
268	Setting MALLOC_DEBUG does NOT provide an automated mechanism for
269	checking that all accesses to malloced memory stay within their
270	bounds. However, there are several add-ons and adaptations of this
271	or other mallocs available that do this.
272	*/
273
274	#ifndef MALLOC_DEBUG
275	#define MALLOC_DEBUG 0
276	#endif
277
278	#ifdef NDEBUG
279	# define assert(expr) ((void) 0)
280	#else
281	# define assert(expr) \
282	((expr) \
283	? ((void) 0) \
284	: __malloc_assert (#expr, __FILE__, __LINE__, __func__))
285
286	extern const char *__progname;
287
288	static void
289	__malloc_assert (const char assertion, const* char file, unsigned* int line,
290	const char *function)
291	{
292	(void) __fxprintf (NULL, "%s%s%s:%u: %s%sAssertion `%s' failed.\n",
293	__progname, __progname[`0`] ? ": " : "",
294	file, line,
295	function ? function : "", function ? ": " : "",
296	assertion);
297	fflush (stderr);
298	abort ();
299	}
300	#endif
301
302	#if USE_TCACHE
303	/ We want 64 entries. This is an arbitrary limit, which tunables can reduce. /
304	# define TCACHE_MAX_BINS 64
305	# define MAX_TCACHE_SIZE tidx2usize (TCACHE_MAX_BINS-1)
306
307	/ Only used to pre-fill the tunables. /
308	# define tidx2usize(idx) (((size_t) idx) * MALLOC_ALIGNMENT + MINSIZE - SIZE_SZ)
309
310	/ When "x" is from chunksize(). /
311	# define csize2tidx(x) (((x) - MINSIZE + MALLOC_ALIGNMENT - 1) / MALLOC_ALIGNMENT)
312	/ When "x" is a user-provided size. /
313	# define usize2tidx(x) csize2tidx (request2size (x))
314
315	/ With rounding and alignment, the bins are...*
316	idx 0 bytes 0..24 (64-bit) or 0..12 (32-bit)
317	idx 1 bytes 25..40 or 13..20
318	idx 2 bytes 41..56 or 21..28
319	etc. /*
320
321	/ This is another arbitrary limit, which tunables can change. Each*
322	tcache bin will hold at most this number of chunks. /*
323	# define TCACHE_FILL_COUNT 7
324	#endif
325
326
327	/*
328	REALLOC_ZERO_BYTES_FREES should be set if a call to
329	realloc with zero bytes should be the same as a call to free.
330	This is required by the C standard. Otherwise, since this malloc
331	returns a unique pointer for malloc(0), so does realloc(p, 0).
332	*/
333
334	#ifndef REALLOC_ZERO_BYTES_FREES
335	#define REALLOC_ZERO_BYTES_FREES 1
336	#endif
337
338	/*
339	TRIM_FASTBINS controls whether free() of a very small chunk can
340	immediately lead to trimming. Setting to true (1) can reduce memory
341	footprint, but will almost always slow down programs that use a lot
342	of small chunks.
343
344	Define this only if you are willing to give up some speed to more
345	aggressively reduce system-level memory footprint when releasing
346	memory in programs that use many small chunks. You can get
347	essentially the same effect by setting MXFAST to 0, but this can
348	lead to even greater slowdowns in programs using many small chunks.
349	TRIM_FASTBINS is an in-between compile-time option, that disables
350	only those chunks bordering topmost memory from being placed in
351	fastbins.
352	*/
353
354	#ifndef TRIM_FASTBINS
355	#define TRIM_FASTBINS 0
356	#endif
357
358
359	/ Definition for getting more memory from the OS. /
360	#define MORECORE (*__morecore)
361	#define MORECORE_FAILURE 0
362	void * __default_morecore (ptrdiff_t);
363	void (__morecore)(ptrdiff_t) = __default_morecore;
364
365
366	#include <string.h>
367
368	/*
369	MORECORE-related declarations. By default, rely on sbrk
370	*/
371
372
373	/*
374	MORECORE is the name of the routine to call to obtain more memory
375	from the system. See below for general guidance on writing
376	alternative MORECORE functions, as well as a version for WIN32 and a
377	sample version for pre-OSX macos.
378	*/
379
380	#ifndef MORECORE
381	#define MORECORE sbrk
382	#endif
383
384	/*
385	MORECORE_FAILURE is the value returned upon failure of MORECORE
386	as well as mmap. Since it cannot be an otherwise valid memory address,
387	and must reflect values of standard sys calls, you probably ought not
388	try to redefine it.
389	*/
390
391	#ifndef MORECORE_FAILURE
392	#define MORECORE_FAILURE (-1)
393	#endif
394
395	/*
396	If MORECORE_CONTIGUOUS is true, take advantage of fact that
397	consecutive calls to MORECORE with positive arguments always return
398	contiguous increasing addresses. This is true of unix sbrk. Even
399	if not defined, when regions happen to be contiguous, malloc will
400	permit allocations spanning regions obtained from different
401	calls. But defining this when applicable enables some stronger
402	consistency checks and space efficiencies.
403	*/
404
405	#ifndef MORECORE_CONTIGUOUS
406	#define MORECORE_CONTIGUOUS 1
407	#endif
408
409	/*
410	Define MORECORE_CANNOT_TRIM if your version of MORECORE
411	cannot release space back to the system when given negative
412	arguments. This is generally necessary only if you are using
413	a hand-crafted MORECORE function that cannot handle negative arguments.
414	*/
415
416	/ #define MORECORE_CANNOT_TRIM /
417
418	/ MORECORE_CLEARS (default 1)*
419	The degree to which the routine mapped to MORECORE zeroes out
420	memory: never (0), only for newly allocated space (1) or always
421	(2). The distinction between (1) and (2) is necessary because on
422	some systems, if the application first decrements and then
423	increments the break value, the contents of the reallocated space
424	are unspecified.
425	*/
426
427	#ifndef MORECORE_CLEARS
428	# define MORECORE_CLEARS 1
429	#endif
430
431
432	/*
433	MMAP_AS_MORECORE_SIZE is the minimum mmap size argument to use if
434	sbrk fails, and mmap is used as a backup. The value must be a
435	multiple of page size. This backup strategy generally applies only
436	when systems have "holes" in address space, so sbrk cannot perform
437	contiguous expansion, but there is still space available on system.
438	On systems for which this is known to be useful (i.e. most linux
439	kernels), this occurs only when programs allocate huge amounts of
440	memory. Between this, and the fact that mmap regions tend to be
441	limited, the size should be large, to avoid too many mmap calls and
442	thus avoid running out of kernel resources. /*
443
444	#ifndef MMAP_AS_MORECORE_SIZE
445	#define MMAP_AS_MORECORE_SIZE (1024 * 1024)
446	#endif
447
448	/*
449	Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
450	large blocks.
451	*/
452
453	#ifndef HAVE_MREMAP
454	#define HAVE_MREMAP 0
455	#endif
456
457	/ We may need to support __malloc_initialize_hook for backwards*
458	compatibility. /*
459
460	#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_24)
461	# define HAVE_MALLOC_INIT_HOOK 1
462	#else
463	# define HAVE_MALLOC_INIT_HOOK 0
464	#endif
465
466
467	/*
468	This version of malloc supports the standard SVID/XPG mallinfo
469	routine that returns a struct containing usage properties and
470	statistics. It should work on any SVID/XPG compliant system that has
471	a /usr/include/malloc.h defining struct mallinfo. (If you'd like to
472	install such a thing yourself, cut out the preliminary declarations
473	as described above and below and save them in a malloc.h file. But
474	there's no compelling reason to bother to do this.)
475
476	The main declaration needed is the mallinfo struct that is returned
477	(by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
478	bunch of fields that are not even meaningful in this version of
479	malloc. These fields are are instead filled by mallinfo() with
480	other numbers that might be of interest.
481	*/
482
483
484	/ ---------- description of public routines ------------ /
485
486	/*
487	malloc(size_t n)
488	Returns a pointer to a newly allocated chunk of at least n bytes, or null
489	if no space is available. Additionally, on failure, errno is
490	set to ENOMEM on ANSI C systems.
491
492	If n is zero, malloc returns a minumum-sized chunk. (The minimum
493	size is 16 bytes on most 32bit systems, and 24 or 32 bytes on 64bit
494	systems.) On most systems, size_t is an unsigned type, so calls
495	with negative arguments are interpreted as requests for huge amounts
496	of space, which will often fail. The maximum supported value of n
497	differs across systems, but is in all cases less than the maximum
498	representable value of a size_t.
499	*/
500	void* __libc_malloc(size_t);
501	libc_hidden_proto (__libc_malloc)
502
503	/*
504	free(void p)*
505	Releases the chunk of memory pointed to by p, that had been previously
506	allocated using malloc or a related routine such as realloc.
507	It has no effect if p is null. It can have arbitrary (i.e., bad!)
508	effects if p has already been freed.
509
510	Unless disabled (using mallopt), freeing very large spaces will
511	when possible, automatically trigger operations that give
512	back unused memory to the system, thus reducing program footprint.
513	*/
514	void __libc_free(void*);
515	libc_hidden_proto (__libc_free)
516
517	/*
518	calloc(size_t n_elements, size_t element_size);
519	Returns a pointer to n_elements element_size bytes, with all locations*
520	set to zero.
521	*/
522	void* __libc_calloc(size_t, size_t);
523
524	/*
525	realloc(void p, size_t n)*
526	Returns a pointer to a chunk of size n that contains the same data
527	as does chunk p up to the minimum of (n, p's size) bytes, or null
528	if no space is available.
529
530	The returned pointer may or may not be the same as p. The algorithm
531	prefers extending p when possible, otherwise it employs the
532	equivalent of a malloc-copy-free sequence.
533
534	If p is null, realloc is equivalent to malloc.
535
536	If space is not available, realloc returns null, errno is set (if on
537	ANSI) and p is NOT freed.
538
539	if n is for fewer bytes than already held by p, the newly unused
540	space is lopped off and freed if possible. Unless the #define
541	REALLOC_ZERO_BYTES_FREES is set, realloc with a size argument of
542	zero (re)allocates a minimum-sized chunk.
543
544	Large chunks that were internally obtained via mmap will always be
545	grown using malloc-copy-free sequences unless the system supports
546	MREMAP (currently only linux).
547
548	The old unix realloc convention of allowing the last-free'd chunk
549	to be used as an argument to realloc is not supported.
550	*/
551	void* __libc_realloc(void*, size_t);
552	libc_hidden_proto (__libc_realloc)
553
554	/*
555	memalign(size_t alignment, size_t n);
556	Returns a pointer to a newly allocated chunk of n bytes, aligned
557	in accord with the alignment argument.
558
559	The alignment argument should be a power of two. If the argument is
560	not a power of two, the nearest greater power is used.
561	8-byte alignment is guaranteed by normal malloc calls, so don't
562	bother calling memalign with an argument of 8 or less.
563
564	Overreliance on memalign is a sure way to fragment space.
565	*/
566	void* __libc_memalign(size_t, size_t);
567	libc_hidden_proto (__libc_memalign)
568
569	/*
570	valloc(size_t n);
571	Equivalent to memalign(pagesize, n), where pagesize is the page
572	size of the system. If the pagesize is unknown, 4096 is used.
573	*/
574	void* __libc_valloc(size_t);
575
576
577
578	/*
579	mallopt(int parameter_number, int parameter_value)
580	Sets tunable parameters The format is to provide a
581	(parameter-number, parameter-value) pair. mallopt then sets the
582	corresponding parameter to the argument value if it can (i.e., so
583	long as the value is meaningful), and returns 1 if successful else
584	0. SVID/XPG/ANSI defines four standard param numbers for mallopt,
585	normally defined in malloc.h. Only one of these (M_MXFAST) is used
586	in this malloc. The others (M_NLBLKS, M_GRAIN, M_KEEP) don't apply,
587	so setting them has no effect. But this malloc also supports four
588	other options in mallopt. See below for details. Briefly, supported
589	parameters are as follows (listed defaults are for "typical"
590	configurations).
591
592	Symbol param # default allowed param values
593	M_MXFAST 1 64 0-80 (0 disables fastbins)
594	M_TRIM_THRESHOLD -1 1281024 any (-1U disables trimming)*
595	M_TOP_PAD -2 0 any
596	M_MMAP_THRESHOLD -3 1281024 any (or 0 if no MMAP support)*
597	M_MMAP_MAX -4 65536 any (0 disables use of mmap)
598	*/
599	int __libc_mallopt(int, int);
600	libc_hidden_proto (__libc_mallopt)
601
602
603	/*
604	mallinfo()
605	Returns (by copy) a struct containing various summary statistics:
606
607	arena: current total non-mmapped bytes allocated from system
608	ordblks: the number of free chunks
609	smblks: the number of fastbin blocks (i.e., small chunks that
610	have been freed but not use resused or consolidated)
611	hblks: current number of mmapped regions
612	hblkhd: total bytes held in mmapped regions
613	usmblks: always 0
614	fsmblks: total bytes held in fastbin blocks
615	uordblks: current total allocated space (normal or mmapped)
616	fordblks: total free space
617	keepcost: the maximum number of bytes that could ideally be released
618	back to system via malloc_trim. ("ideally" means that
619	it ignores page restrictions etc.)
620
621	Because these fields are ints, but internal bookkeeping may
622	be kept as longs, the reported values may wrap around zero and
623	thus be inaccurate.
624	*/
625	struct mallinfo __libc_mallinfo(void);
626
627
628	/*
629	pvalloc(size_t n);
630	Equivalent to valloc(minimum-page-that-holds(n)), that is,
631	round up n to nearest pagesize.
632	*/
633	void* __libc_pvalloc(size_t);
634
635	/*
636	malloc_trim(size_t pad);
637
638	If possible, gives memory back to the system (via negative
639	arguments to sbrk) if there is unused memory at the `high' end of
640	the malloc pool. You can call this after freeing large blocks of
641	memory to potentially reduce the system-level memory requirements
642	of a program. However, it cannot guarantee to reduce memory. Under
643	some allocation patterns, some large free blocks of memory will be
644	locked between two used chunks, so they cannot be given back to
645	the system.
646
647	The `pad' argument to malloc_trim represents the amount of free
648	trailing space to leave untrimmed. If this argument is zero,
649	only the minimum amount of memory to maintain internal data
650	structures will be left (one page or less). Non-zero arguments
651	can be supplied to maintain enough trailing space to service
652	future expected allocations without having to re-obtain memory
653	from the system.
654
655	Malloc_trim returns 1 if it actually released any memory, else 0.
656	On systems that do not support "negative sbrks", it will always
657	return 0.
658	*/
659	int __malloc_trim(size_t);
660
661	/*
662	malloc_usable_size(void p);*
663
664	Returns the number of bytes you can actually use in
665	an allocated chunk, which may be more than you requested (although
666	often not) due to alignment and minimum size constraints.
667	You can use this many bytes without worrying about
668	overwriting other allocated objects. This is not a particularly great
669	programming practice. malloc_usable_size can be more useful in
670	debugging and assertions, for example:
671
672	p = malloc(n);
673	assert(malloc_usable_size(p) >= 256);
674
675	*/
676	size_t __malloc_usable_size(void*);
677
678	/*
679	malloc_stats();
680	Prints on stderr the amount of space obtained from the system (both
681	via sbrk and mmap), the maximum amount (which may be more than
682	current if malloc_trim and/or munmap got called), and the current
683	number of bytes allocated via malloc (or realloc, etc) but not yet
684	freed. Note that this is the number of bytes allocated, not the
685	number requested. It will be larger than the number requested
686	because of alignment and bookkeeping overhead. Because it includes
687	alignment wastage as being in use, this figure may be greater than
688	zero even when no user-level chunks are allocated.
689
690	The reported current and maximum system memory can be inaccurate if
691	a program makes other calls to system memory allocation functions
692	(normally sbrk) outside of malloc.
693
694	malloc_stats prints only the most commonly interesting statistics.
695	More information can be obtained by calling mallinfo.
696
697	*/
698	void __malloc_stats(void);
699
700	/*
701	malloc_get_state(void);
702
703	Returns the state of all malloc variables in an opaque data
704	structure.
705	*/
706	void* __malloc_get_state(void);
707
708	/*
709	malloc_set_state(void state);*
710
711	Restore the state of all malloc variables from data obtained with
712	malloc_get_state().
713	*/
714	int __malloc_set_state(void*);
715
716	/*
717	posix_memalign(void memptr, size_t alignment, size_t size);
718
719	POSIX wrapper like memalign(), checking for validity of size.
720	*/
721	int __posix_memalign(void **, size_t, size_t);
722
723	/ mallopt tuning options /
724
725	/*
726	M_MXFAST is the maximum request size used for "fastbins", special bins
727	that hold returned chunks without consolidating their spaces. This
728	enables future requests for chunks of the same size to be handled
729	very quickly, but can increase fragmentation, and thus increase the
730	overall memory footprint of a program.
731
732	This malloc manages fastbins very conservatively yet still
733	efficiently, so fragmentation is rarely a problem for values less
734	than or equal to the default. The maximum supported value of MXFAST
735	is 80. You wouldn't want it any higher than this anyway. Fastbins
736	are designed especially for use with many small structs, objects or
737	strings -- the default handles structs/objects/arrays with sizes up
738	to 8 4byte fields, or small strings representing words, tokens,
739	etc. Using fastbins for larger objects normally worsens
740	fragmentation without improving speed.
741
742	M_MXFAST is set in REQUEST size units. It is internally used in
743	chunksize units, which adds padding and alignment. You can reduce
744	M_MXFAST to 0 to disable all use of fastbins. This causes the malloc
745	algorithm to be a closer approximation of fifo-best-fit in all cases,
746	not just for larger requests, but will generally cause it to be
747	slower.
748	*/
749
750
751	/ M_MXFAST is a standard SVID/XPG tuning option, usually listed in malloc.h /
752	#ifndef M_MXFAST
753	#define M_MXFAST 1
754	#endif
755
756	#ifndef DEFAULT_MXFAST
757	#define DEFAULT_MXFAST (64 * SIZE_SZ / 4)
758	#endif
759
760
761	/*
762	M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
763	to keep before releasing via malloc_trim in free().
764
765	Automatic trimming is mainly useful in long-lived programs.
766	Because trimming via sbrk can be slow on some systems, and can
767	sometimes be wasteful (in cases where programs immediately
768	afterward allocate more large chunks) the value should be high
769	enough so that your overall system performance would improve by
770	releasing this much memory.
771
772	The trim threshold and the mmap control parameters (see below)
773	can be traded off with one another. Trimming and mmapping are
774	two different ways of releasing unused memory back to the
775	system. Between these two, it is often possible to keep
776	system-level demands of a long-lived program down to a bare
777	minimum. For example, in one test suite of sessions measuring
778	the XF86 X server on Linux, using a trim threshold of 128K and a
779	mmap threshold of 192K led to near-minimal long term resource
780	consumption.
781
782	If you are using this malloc in a long-lived program, it should
783	pay to experiment with these values. As a rough guide, you
784	might set to a value close to the average size of a process
785	(program) running on your system. Releasing this much memory
786	would allow such a process to run in memory. Generally, it's
787	worth it to tune for trimming rather tham memory mapping when a
788	program undergoes phases where several large chunks are
789	allocated and released in ways that can reuse each other's
790	storage, perhaps mixed with phases where there are no such
791	chunks at all. And in well-behaved long-lived programs,
792	controlling release of large blocks via trimming versus mapping
793	is usually faster.
794
795	However, in most programs, these parameters serve mainly as
796	protection against the system-level effects of carrying around
797	massive amounts of unneeded memory. Since frequent calls to
798	sbrk, mmap, and munmap otherwise degrade performance, the default
799	parameters are set to relatively high values that serve only as
800	safeguards.
801
802	The trim value It must be greater than page size to have any useful
803	effect. To disable trimming completely, you can set to
804	(unsigned long)(-1)
805
806	Trim settings interact with fastbin (MXFAST) settings: Unless
807	TRIM_FASTBINS is defined, automatic trimming never takes place upon
808	freeing a chunk with size less than or equal to MXFAST. Trimming is
809	instead delayed until subsequent freeing of larger chunks. However,
810	you can still force an attempted trim by calling malloc_trim.
811
812	Also, trimming is not generally possible in cases where
813	the main arena is obtained via mmap.
814
815	Note that the trick some people use of mallocing a huge space and
816	then freeing it at program startup, in an attempt to reserve system
817	memory, doesn't have the intended effect under automatic trimming,
818	since that memory will immediately be returned to the system.
819	*/
820
821	#define M_TRIM_THRESHOLD -1
822
823	#ifndef DEFAULT_TRIM_THRESHOLD
824	#define DEFAULT_TRIM_THRESHOLD (128 * 1024)
825	#endif
826
827	/*
828	M_TOP_PAD is the amount of extra `padding' space to allocate or
829	retain whenever sbrk is called. It is used in two ways internally:
830
831	* When sbrk is called to extend the top of the arena to satisfy
832	a new malloc request, this much padding is added to the sbrk
833	request.
834
835	* When malloc_trim is called automatically from free(),
836	it is used as the `pad' argument.
837
838	In both cases, the actual amount of padding is rounded
839	so that the end of the arena is always a system page boundary.
840
841	The main reason for using padding is to avoid calling sbrk so
842	often. Having even a small pad greatly reduces the likelihood
843	that nearly every malloc request during program start-up (or
844	after trimming) will invoke sbrk, which needlessly wastes
845	time.
846
847	Automatic rounding-up to page-size units is normally sufficient
848	to avoid measurable overhead, so the default is 0. However, in
849	systems where sbrk is relatively slow, it can pay to increase
850	this value, at the expense of carrying around more memory than
851	the program needs.
852	*/
853
854	#define M_TOP_PAD -2
855
856	#ifndef DEFAULT_TOP_PAD
857	#define DEFAULT_TOP_PAD (0)
858	#endif
859
860	/*
861	MMAP_THRESHOLD_MAX and _MIN are the bounds on the dynamically
862	adjusted MMAP_THRESHOLD.
863	*/
864
865	#ifndef DEFAULT_MMAP_THRESHOLD_MIN
866	#define DEFAULT_MMAP_THRESHOLD_MIN (128 * 1024)
867	#endif
868
869	#ifndef DEFAULT_MMAP_THRESHOLD_MAX
870	/ For 32-bit platforms we cannot increase the maximum mmap*
871	threshold much because it is also the minimum value for the
872	maximum heap size and its alignment. Going above 512k (i.e., 1M
873	for new heaps) wastes too much address space. /*
874	# if __WORDSIZE == 32
875	# define DEFAULT_MMAP_THRESHOLD_MAX (512 * 1024)
876	# else
877	# define DEFAULT_MMAP_THRESHOLD_MAX (4 * 1024 * 1024 * sizeof(long))
878	# endif
879	#endif
880
881	/*
882	M_MMAP_THRESHOLD is the request size threshold for using mmap()
883	to service a request. Requests of at least this size that cannot
884	be allocated using already-existing space will be serviced via mmap.
885	(If enough normal freed space already exists it is used instead.)
886
887	Using mmap segregates relatively large chunks of memory so that
888	they can be individually obtained and released from the host
889	system. A request serviced through mmap is never reused by any
890	other request (at least not directly; the system may just so
891	happen to remap successive requests to the same locations).
892
893	Segregating space in this way has the benefits that:
894
895	1. Mmapped space can ALWAYS be individually released back
896	to the system, which helps keep the system level memory
897	demands of a long-lived program low.
898	2. Mapped memory can never become `locked' between
899	other chunks, as can happen with normally allocated chunks, which
900	means that even trimming via malloc_trim would not release them.
901	3. On some systems with "holes" in address spaces, mmap can obtain
902	memory that sbrk cannot.
903
904	However, it has the disadvantages that:
905
906	1. The space cannot be reclaimed, consolidated, and then
907	used to service later requests, as happens with normal chunks.
908	2. It can lead to more wastage because of mmap page alignment
909	requirements
910	3. It causes malloc performance to be more dependent on host
911	system memory management support routines which may vary in
912	implementation quality and may impose arbitrary
913	limitations. Generally, servicing a request via normal
914	malloc steps is faster than going through a system's mmap.
915
916	The advantages of mmap nearly always outweigh disadvantages for
917	"large" chunks, but the value of "large" varies across systems. The
918	default is an empirically derived value that works well in most
919	systems.
920
921
922	Update in 2006:
923	The above was written in 2001. Since then the world has changed a lot.
924	Memory got bigger. Applications got bigger. The virtual address space
925	layout in 32 bit linux changed.
926
927	In the new situation, brk() and mmap space is shared and there are no
928	artificial limits on brk size imposed by the kernel. What is more,
929	applications have started using transient allocations larger than the
930	128Kb as was imagined in 2001.
931
932	The price for mmap is also high now; each time glibc mmaps from the
933	kernel, the kernel is forced to zero out the memory it gives to the
934	application. Zeroing memory is expensive and eats a lot of cache and
935	memory bandwidth. This has nothing to do with the efficiency of the
936	virtual memory system, by doing mmap the kernel just has no choice but
937	to zero.
938
939	In 2001, the kernel had a maximum size for brk() which was about 800
940	megabytes on 32 bit x86, at that point brk() would hit the first
941	mmaped shared libaries and couldn't expand anymore. With current 2.6
942	kernels, the VA space layout is different and brk() and mmap
943	both can span the entire heap at will.
944
945	Rather than using a static threshold for the brk/mmap tradeoff,
946	we are now using a simple dynamic one. The goal is still to avoid
947	fragmentation. The old goals we kept are
948	1) try to get the long lived large allocations to use mmap()
949	2) really large allocations should always use mmap()
950	and we're adding now:
951	3) transient allocations should use brk() to avoid forcing the kernel
952	having to zero memory over and over again
953
954	The implementation works with a sliding threshold, which is by default
955	limited to go between 128Kb and 32Mb (64Mb for 64 bitmachines) and starts
956	out at 128Kb as per the 2001 default.
957
958	This allows us to satisfy requirement 1) under the assumption that long
959	lived allocations are made early in the process' lifespan, before it has
960	started doing dynamic allocations of the same size (which will
961	increase the threshold).
962
963	The upperbound on the threshold satisfies requirement 2)
964
965	The threshold goes up in value when the application frees memory that was
966	allocated with the mmap allocator. The idea is that once the application
967	starts freeing memory of a certain size, it's highly probable that this is
968	a size the application uses for transient allocations. This estimator
969	is there to satisfy the new third requirement.
970
971	*/
972
973	#define M_MMAP_THRESHOLD -3
974
975	#ifndef DEFAULT_MMAP_THRESHOLD
976	#define DEFAULT_MMAP_THRESHOLD DEFAULT_MMAP_THRESHOLD_MIN
977	#endif
978
979	/*
980	M_MMAP_MAX is the maximum number of requests to simultaneously
981	service using mmap. This parameter exists because
982	some systems have a limited number of internal tables for
983	use by mmap, and using more than a few of them may degrade
984	performance.
985
986	The default is set to a value that serves only as a safeguard.
987	Setting to 0 disables use of mmap for servicing large requests.
988	*/
989
990	#define M_MMAP_MAX -4
991
992	#ifndef DEFAULT_MMAP_MAX
993	#define DEFAULT_MMAP_MAX (65536)
994	#endif
995
996	#include <malloc.h>
997
998	#ifndef RETURN_ADDRESS
999	#define RETURN_ADDRESS(X_) (NULL)
1000	#endif
1001
1002	/ On some platforms we can compile internal, not exported functions better.*
1003	Let the environment provide a macro and define it to be empty if it
1004	is not available. /*
1005	#ifndef internal_function
1006	# define internal_function
1007	#endif
1008
1009	/ Forward declarations. /
1010	struct malloc_chunk;
1011	typedef struct malloc_chunk* mchunkptr;
1012
1013	/ Internal routines. /
1014
1015	static void* _int_malloc(mstate, size_t);
1016	static void _int_free(mstate, mchunkptr, int);
1017	static void* _int_realloc(mstate, mchunkptr, INTERNAL_SIZE_T,
1018	INTERNAL_SIZE_T);
1019	static void* _int_memalign(mstate, size_t, size_t);
1020	static void* _mid_memalign(size_t, size_t, void *);
1021
1022	static void malloc_printerr(int action, const char str, void* *ptr, mstate av);
1023
1024	static void* internal_function mem2mem_check(void *p, size_t sz);
1025	static int internal_function top_check(void);
1026	static void internal_function munmap_chunk(mchunkptr p);
1027	#if HAVE_MREMAP
1028	static mchunkptr internal_function mremap_chunk(mchunkptr p, size_t new_size);
1029	#endif
1030
1031	static void* malloc_check(size_t sz, const void *caller);
1032	static void free_check(void* mem, const void *caller);
1033	static void* realloc_check(void* oldmem, size_t bytes,
1034	const void *caller);
1035	static void* memalign_check(size_t alignment, size_t bytes,
1036	const void *caller);
1037
1038	/ ------------------ MMAP support ------------------ /
1039
1040
1041	#include <fcntl.h>
1042	#include <sys/mman.h>
1043
1044	#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
1045	# define MAP_ANONYMOUS MAP_ANON
1046	#endif
1047
1048	#ifndef MAP_NORESERVE
1049	# define MAP_NORESERVE 0
1050	#endif
1051
1052	#define MMAP(addr, size, prot, flags) \
1053	__mmap((addr), (size), (prot), (flags)\|MAP_ANONYMOUS\|MAP_PRIVATE, -1, 0)
1054
1055
1056	/*
1057	----------------------- Chunk representations -----------------------
1058	*/
1059
1060
1061	/*
1062	This struct declaration is misleading (but accurate and necessary).
1063	It declares a "view" into memory allowing access to necessary
1064	fields at known offsets from a given base. See explanation below.
1065	*/
1066
1067	struct malloc_chunk {
1068
1069	INTERNAL_SIZE_T mchunk_prev_size; / Size of previous chunk (if free). /
1070	INTERNAL_SIZE_T mchunk_size; / Size in bytes, including overhead. /
1071
1072	struct malloc_chunk* fd; / double links -- used only if free. /
1073	struct malloc_chunk* bk;
1074
1075	/ Only used for large blocks: pointer to next larger size. /
1076	struct malloc_chunk* fd_nextsize; / double links -- used only if free. /
1077	struct malloc_chunk* bk_nextsize;
1078	};
1079
1080
1081	/*
1082	malloc_chunk details:
1083
1084	(The following includes lightly edited explanations by Colin Plumb.)
1085
1086	Chunks of memory are maintained using a `boundary tag' method as
1087	described in e.g., Knuth or Standish. (See the paper by Paul
1088	Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
1089	survey of such techniques.) Sizes of free chunks are stored both
1090	in the front of each chunk and at the end. This makes
1091	consolidating fragmented chunks into bigger chunks very fast. The
1092	size fields also hold bits representing whether chunks are free or
1093	in use.
1094
1095	An allocated chunk looks like this:
1096
1097
1098	chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1099	\| Size of previous chunk, if unallocated (P clear) \|
1100	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1101	\| Size of chunk, in bytes \|A\|M\|P\|
1102	mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1103	\| User data starts here... .
1104	. .
1105	. (malloc_usable_size() bytes) .
1106	. \|
1107	nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1108	\| (size of chunk, but used for application data) \|
1109	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1110	\| Size of next chunk, in bytes \|A\|0\|1\|
1111	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1112
1113	Where "chunk" is the front of the chunk for the purpose of most of
1114	the malloc code, but "mem" is the pointer that is returned to the
1115	user. "Nextchunk" is the beginning of the next contiguous chunk.
1116
1117	Chunks always begin on even word boundaries, so the mem portion
1118	(which is returned to the user) is also on an even word boundary, and
1119	thus at least double-word aligned.
1120
1121	Free chunks are stored in circular doubly-linked lists, and look like this:
1122
1123	chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1124	\| Size of previous chunk, if unallocated (P clear) \|
1125	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1126	`head:' \| Size of chunk, in bytes \|A\|0\|P\|
1127	mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1128	\| Forward pointer to next chunk in list \|
1129	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1130	\| Back pointer to previous chunk in list \|
1131	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1132	\| Unused space (may be 0 bytes long) .
1133	. .
1134	. \|
1135	nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1136	`foot:' \| Size of chunk, in bytes \|
1137	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1138	\| Size of next chunk, in bytes \|A\|0\|0\|
1139	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1140
1141	The P (PREV_INUSE) bit, stored in the unused low-order bit of the
1142	chunk size (which is always a multiple of two words), is an in-use
1143	bit for the previous* chunk. If that bit is clear, then the*
1144	word before the current chunk size contains the previous chunk
1145	size, and can be used to find the front of the previous chunk.
1146	The very first chunk allocated always has this bit set,
1147	preventing access to non-existent (or non-owned) memory. If
1148	prev_inuse is set for any given chunk, then you CANNOT determine
1149	the size of the previous chunk, and might even get a memory
1150	addressing fault when trying to do so.
1151
1152	The A (NON_MAIN_ARENA) bit is cleared for chunks on the initial,
1153	main arena, described by the main_arena variable. When additional
1154	threads are spawned, each thread receives its own arena (up to a
1155	configurable limit, after which arenas are reused for multiple
1156	threads), and the chunks in these arenas have the A bit set. To
1157	find the arena for a chunk on such a non-main arena, heap_for_ptr
1158	performs a bit mask operation and indirection through the ar_ptr
1159	member of the per-heap header heap_info (see arena.c).
1160
1161	Note that the `foot' of the current chunk is actually represented
1162	as the prev_size of the NEXT chunk. This makes it easier to
1163	deal with alignments etc but can be very confusing when trying
1164	to extend or adapt this code.
1165
1166	The three exceptions to all this are:
1167
1168	1. The special chunk `top' doesn't bother using the
1169	trailing size field since there is no next contiguous chunk
1170	that would have to index off it. After initialization, `top'
1171	is forced to always exist. If it would become less than
1172	MINSIZE bytes long, it is replenished.
1173
1174	2. Chunks allocated via mmap, which have the second-lowest-order
1175	bit M (IS_MMAPPED) set in their size fields. Because they are
1176	allocated one-by-one, each must contain its own trailing size
1177	field. If the M bit is set, the other bits are ignored
1178	(because mmapped chunks are neither in an arena, nor adjacent
1179	to a freed chunk). The M bit is also used for chunks which
1180	originally came from a dumped heap via malloc_set_state in
1181	hooks.c.
1182
1183	3. Chunks in fastbins are treated as allocated chunks from the
1184	point of view of the chunk allocator. They are consolidated
1185	with their neighbors only in bulk, in malloc_consolidate.
1186	*/
1187
1188	/*
1189	---------- Size and alignment checks and conversions ----------
1190	*/
1191
1192	/ conversion from malloc headers to user pointers, and back /
1193
1194	#define chunk2mem(p) ((void)((char)(p) + 2*SIZE_SZ))
1195	#define mem2chunk(mem) ((mchunkptr)((char)(mem) - 2SIZE_SZ))
1196
1197	/ The smallest possible chunk /
1198	#define MIN_CHUNK_SIZE (offsetof(struct malloc_chunk, fd_nextsize))
1199
1200	/ The smallest size we can malloc is an aligned minimal chunk /
1201
1202	#define MINSIZE \
1203	(unsigned long)(((MIN_CHUNK_SIZE+MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK))
1204
1205	/ Check if m has acceptable alignment /
1206
1207	#define aligned_OK(m) (((unsigned long)(m) & MALLOC_ALIGN_MASK) == 0)
1208
1209	#define misaligned_chunk(p) \
1210	((uintptr_t)(MALLOC_ALIGNMENT == 2 * SIZE_SZ ? (p) : chunk2mem (p)) \
1211	& MALLOC_ALIGN_MASK)
1212
1213
1214	/*
1215	Check if a request is so large that it would wrap around zero when
1216	padded and aligned. To simplify some other code, the bound is made
1217	low enough so that adding MINSIZE will also not wrap around zero.
1218	*/
1219
1220	#define REQUEST_OUT_OF_RANGE(req) \
1221	((unsigned long) (req) >= \
1222	(unsigned long) (INTERNAL_SIZE_T) (-2 * MINSIZE))
1223
1224	/ pad request bytes into a usable size -- internal version /
1225
1226	#define request2size(req) \
1227	(((req) + SIZE_SZ + MALLOC_ALIGN_MASK < MINSIZE) ? \
1228	MINSIZE : \
1229	((req) + SIZE_SZ + MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK)
1230
1231	/ Same, except also perform argument check /
1232
1233	#define checked_request2size(req, sz) \
1234	if (REQUEST_OUT_OF_RANGE (req)) { \
1235	__set_errno (ENOMEM); \
1236	return 0; \
1237	} \
1238	(sz) = request2size (req);
1239
1240	/*
1241	--------------- Physical chunk operations ---------------
1242	*/
1243
1244
1245	/ size field is or'ed with PREV_INUSE when previous adjacent chunk in use /
1246	#define PREV_INUSE 0x1
1247
1248	/ extract inuse bit of previous chunk /
1249	#define prev_inuse(p) ((p)->mchunk_size & PREV_INUSE)
1250
1251
1252	/ size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() /
1253	#define IS_MMAPPED 0x2
1254
1255	/ check for mmap()'ed chunk /
1256	#define chunk_is_mmapped(p) ((p)->mchunk_size & IS_MMAPPED)
1257
1258
1259	/ size field is or'ed with NON_MAIN_ARENA if the chunk was obtained*
1260	from a non-main arena. This is only set immediately before handing
1261	the chunk to the user, if necessary. /*
1262	#define NON_MAIN_ARENA 0x4
1263
1264	/ Check for chunk from main arena. /
1265	#define chunk_main_arena(p) (((p)->mchunk_size & NON_MAIN_ARENA) == 0)
1266
1267	/ Mark a chunk as not being on the main arena. /
1268	#define set_non_main_arena(p) ((p)->mchunk_size \|= NON_MAIN_ARENA)
1269
1270
1271	/*
1272	Bits to mask off when extracting size
1273
1274	Note: IS_MMAPPED is intentionally not masked off from size field in
1275	macros for which mmapped chunks should never be seen. This should
1276	cause helpful core dumps to occur if it is tried by accident by
1277	people extending or adapting this malloc.
1278	*/
1279	#define SIZE_BITS (PREV_INUSE \| IS_MMAPPED \| NON_MAIN_ARENA)
1280
1281	/ Get size, ignoring use bits /
1282	#define chunksize(p) (chunksize_nomask (p) & ~(SIZE_BITS))
1283
1284	/ Like chunksize, but do not mask SIZE_BITS. /
1285	#define chunksize_nomask(p) ((p)->mchunk_size)
1286
1287	/ Ptr to next physical malloc_chunk. /
1288	#define next_chunk(p) ((mchunkptr) (((char *) (p)) + chunksize (p)))
1289
1290	/ Size of the chunk below P. Only valid if prev_inuse (P). /
1291	#define prev_size(p) ((p)->mchunk_prev_size)
1292
1293	/ Set the size of the chunk below P. Only valid if prev_inuse (P). /
1294	#define set_prev_size(p, sz) ((p)->mchunk_prev_size = (sz))
1295
1296	/ Ptr to previous physical malloc_chunk. Only valid if prev_inuse (P). /
1297	#define prev_chunk(p) ((mchunkptr) (((char *) (p)) - prev_size (p)))
1298
1299	/ Treat space at ptr + offset as a chunk /
1300	#define chunk_at_offset(p, s) ((mchunkptr) (((char *) (p)) + (s)))
1301
1302	/ extract p's inuse bit /
1303	#define inuse(p) \
1304	((((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size) & PREV_INUSE)
1305
1306	/ set/clear chunk as being inuse without otherwise disturbing /
1307	#define set_inuse(p) \
1308	((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size \|= PREV_INUSE
1309
1310	#define clear_inuse(p) \
1311	((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size &= ~(PREV_INUSE)
1312
1313
1314	/ check/set/clear inuse bits in known places /
1315	#define inuse_bit_at_offset(p, s) \
1316	(((mchunkptr) (((char *) (p)) + (s)))->mchunk_size & PREV_INUSE)
1317
1318	#define set_inuse_bit_at_offset(p, s) \
1319	(((mchunkptr) (((char *) (p)) + (s)))->mchunk_size \|= PREV_INUSE)
1320
1321	#define clear_inuse_bit_at_offset(p, s) \
1322	(((mchunkptr) (((char *) (p)) + (s)))->mchunk_size &= ~(PREV_INUSE))
1323
1324
1325	/ Set size at head, without disturbing its use bit /
1326	#define set_head_size(p, s) ((p)->mchunk_size = (((p)->mchunk_size & SIZE_BITS) \| (s)))
1327
1328	/ Set size/use field /
1329	#define set_head(p, s) ((p)->mchunk_size = (s))
1330
1331	/ Set size at footer (only when chunk is not in use) /
1332	#define set_foot(p, s) (((mchunkptr) ((char *) (p) + (s)))->mchunk_prev_size = (s))
1333
1334
1335	#pragma GCC poison mchunk_size
1336	#pragma GCC poison mchunk_prev_size
1337
1338	/*
1339	-------------------- Internal data structures --------------------
1340
1341	All internal state is held in an instance of malloc_state defined
1342	below. There are no other static variables, except in two optional
1343	cases:
1344	* If USE_MALLOC_LOCK is defined, the mALLOC_MUTEx declared above.
1345	* If mmap doesn't support MAP_ANONYMOUS, a dummy file descriptor
1346	for mmap.
1347
1348	Beware of lots of tricks that minimize the total bookkeeping space
1349	requirements. The result is a little over 1K bytes (for 4byte
1350	pointers and size_t.)
1351	*/
1352
1353	/*
1354	Bins
1355
1356	An array of bin headers for free chunks. Each bin is doubly
1357	linked. The bins are approximately proportionally (log) spaced.
1358	There are a lot of these bins (128). This may look excessive, but
1359	works very well in practice. Most bins hold sizes that are
1360	unusual as malloc request sizes, but are more usual for fragments
1361	and consolidated sets of chunks, which is what these bins hold, so
1362	they can be found quickly. All procedures maintain the invariant
1363	that no consolidated chunk physically borders another one, so each
1364	chunk in a list is known to be preceeded and followed by either
1365	inuse chunks or the ends of memory.
1366
1367	Chunks in bins are kept in size order, with ties going to the
1368	approximately least recently used chunk. Ordering isn't needed
1369	for the small bins, which all contain the same-sized chunks, but
1370	facilitates best-fit allocation for larger chunks. These lists
1371	are just sequential. Keeping them in order almost never requires
1372	enough traversal to warrant using fancier ordered data
1373	structures.
1374
1375	Chunks of the same size are linked with the most
1376	recently freed at the front, and allocations are taken from the
1377	back. This results in LRU (FIFO) allocation order, which tends
1378	to give each chunk an equal opportunity to be consolidated with
1379	adjacent freed chunks, resulting in larger free chunks and less
1380	fragmentation.
1381
1382	To simplify use in double-linked lists, each bin header acts
1383	as a malloc_chunk. This avoids special-casing for headers.
1384	But to conserve space and improve locality, we allocate
1385	only the fd/bk pointers of bins, and then use repositioning tricks
1386	to treat these as the fields of a malloc_chunk.*
1387	*/
1388
1389	typedef struct malloc_chunk *mbinptr;
1390
1391	/ addressing -- note that bin_at(0) does not exist /
1392	#define bin_at(m, i) \
1393	(mbinptr) (((char ) &((m)->bins[((i) - 1) 2])) \
1394	- offsetof (struct malloc_chunk, fd))
1395
1396	/ analog of ++bin /
1397	#define next_bin(b) ((mbinptr) ((char *) (b) + (sizeof (mchunkptr) << 1)))
1398
1399	/ Reminders about list directionality within bins /
1400	#define first(b) ((b)->fd)
1401	#define last(b) ((b)->bk)
1402
1403	/ Take a chunk off a bin list /
1404	#define unlink(AV, P, BK, FD) { \
1405	if (__builtin_expect (chunksize(P) != prev_size (next_chunk(P)), 0)) \
1406	malloc_printerr (check_action, "corrupted size vs. prev_size", P, AV); \
1407	FD = P->fd; \
1408	BK = P->bk; \
1409	if (__builtin_expect (FD->bk != P \|\| BK->fd != P, 0)) \
1410	malloc_printerr (check_action, "corrupted double-linked list", P, AV); \
1411	else { \
1412	FD->bk = BK; \
1413	BK->fd = FD; \
1414	if (!in_smallbin_range (chunksize_nomask (P)) \
1415	&& __builtin_expect (P->fd_nextsize != NULL, 0)) { \
1416	if (__builtin_expect (P->fd_nextsize->bk_nextsize != P, 0) \
1417	\|\| __builtin_expect (P->bk_nextsize->fd_nextsize != P, 0)) \
1418	malloc_printerr (check_action, \
1419	"corrupted double-linked list (not small)", \
1420	P, AV); \
1421	if (FD->fd_nextsize == NULL) { \
1422	if (P->fd_nextsize == P) \
1423	FD->fd_nextsize = FD->bk_nextsize = FD; \
1424	else { \
1425	FD->fd_nextsize = P->fd_nextsize; \
1426	FD->bk_nextsize = P->bk_nextsize; \
1427	P->fd_nextsize->bk_nextsize = FD; \
1428	P->bk_nextsize->fd_nextsize = FD; \
1429	} \
1430	} else { \
1431	P->fd_nextsize->bk_nextsize = P->bk_nextsize; \
1432	P->bk_nextsize->fd_nextsize = P->fd_nextsize; \
1433	} \
1434	} \
1435	} \
1436	}
1437
1438	/*
1439	Indexing
1440
1441	Bins for sizes < 512 bytes contain chunks of all the same size, spaced
1442	8 bytes apart. Larger bins are approximately logarithmically spaced:
1443
1444	64 bins of size 8
1445	32 bins of size 64
1446	16 bins of size 512
1447	8 bins of size 4096
1448	4 bins of size 32768
1449	2 bins of size 262144
1450	1 bin of size what's left
1451
1452	There is actually a little bit of slop in the numbers in bin_index
1453	for the sake of speed. This makes no difference elsewhere.
1454
1455	The bins top out around 1MB because we expect to service large
1456	requests via mmap.
1457
1458	Bin 0 does not exist. Bin 1 is the unordered list; if that would be
1459	a valid chunk size the small bins are bumped up one.
1460	*/
1461
1462	#define NBINS 128
1463	#define NSMALLBINS 64
1464	#define SMALLBIN_WIDTH MALLOC_ALIGNMENT
1465	#define SMALLBIN_CORRECTION (MALLOC_ALIGNMENT > 2 * SIZE_SZ)
1466	#define MIN_LARGE_SIZE ((NSMALLBINS - SMALLBIN_CORRECTION) * SMALLBIN_WIDTH)
1467
1468	#define in_smallbin_range(sz) \
1469	((unsigned long) (sz) < (unsigned long) MIN_LARGE_SIZE)
1470
1471	#define smallbin_index(sz) \
1472	((SMALLBIN_WIDTH == 16 ? (((unsigned) (sz)) >> 4) : (((unsigned) (sz)) >> 3))\
1473	+ SMALLBIN_CORRECTION)
1474
1475	#define largebin_index_32(sz) \
1476	(((((unsigned long) (sz)) >> 6) <= 38) ? 56 + (((unsigned long) (sz)) >> 6) :\
1477	((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
1478	((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
1479	((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
1480	((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
1481	126)
1482
1483	#define largebin_index_32_big(sz) \
1484	(((((unsigned long) (sz)) >> 6) <= 45) ? 49 + (((unsigned long) (sz)) >> 6) :\
1485	((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
1486	((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
1487	((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
1488	((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
1489	126)
1490
1491	// XXX It remains to be seen whether it is good to keep the widths of
1492	// XXX the buckets the same or whether it should be scaled by a factor
1493	// XXX of two as well.
1494	#define largebin_index_64(sz) \
1495	(((((unsigned long) (sz)) >> 6) <= 48) ? 48 + (((unsigned long) (sz)) >> 6) :\
1496	((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
1497	((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
1498	((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
1499	((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
1500	126)
1501
1502	#define largebin_index(sz) \
1503	(SIZE_SZ == 8 ? largebin_index_64 (sz) \
1504	: MALLOC_ALIGNMENT == 16 ? largebin_index_32_big (sz) \
1505	: largebin_index_32 (sz))
1506
1507	#define bin_index(sz) \
1508	((in_smallbin_range (sz)) ? smallbin_index (sz) : largebin_index (sz))
1509
1510
1511	/*
1512	Unsorted chunks
1513
1514	All remainders from chunk splits, as well as all returned chunks,
1515	are first placed in the "unsorted" bin. They are then placed
1516	in regular bins after malloc gives them ONE chance to be used before
1517	binning. So, basically, the unsorted_chunks list acts as a queue,
1518	with chunks being placed on it in free (and malloc_consolidate),
1519	and taken off (to be either used or placed in bins) in malloc.
1520
1521	The NON_MAIN_ARENA flag is never set for unsorted chunks, so it
1522	does not have to be taken into account in size comparisons.
1523	*/
1524
1525	/ The otherwise unindexable 1-bin is used to hold unsorted chunks. /
1526	#define unsorted_chunks(M) (bin_at (M, 1))
1527
1528	/*
1529	Top
1530
1531	The top-most available chunk (i.e., the one bordering the end of
1532	available memory) is treated specially. It is never included in
1533	any bin, is used only if no other chunk is available, and is
1534	released back to the system if it is very large (see
1535	M_TRIM_THRESHOLD). Because top initially
1536	points to its own bin with initial zero size, thus forcing
1537	extension on the first malloc request, we avoid having any special
1538	code in malloc to check whether it even exists yet. But we still
1539	need to do so when getting memory from system, so we make
1540	initial_top treat the bin as a legal but unusable chunk during the
1541	interval between initialization and the first call to
1542	sysmalloc. (This is somewhat delicate, since it relies on
1543	the 2 preceding words to be zero during this interval as well.)
1544	*/
1545
1546	/ Conveniently, the unsorted bin can be used as dummy top on first call /
1547	#define initial_top(M) (unsorted_chunks (M))
1548
1549	/*
1550	Binmap
1551
1552	To help compensate for the large number of bins, a one-level index
1553	structure is used for bin-by-bin searching. `binmap' is a
1554	bitvector recording whether bins are definitely empty so they can
1555	be skipped over during during traversals. The bits are NOT always
1556	cleared as soon as bins are empty, but instead only
1557	when they are noticed to be empty during traversal in malloc.
1558	*/
1559
1560	/ Conservatively use 32 bits per map word, even if on 64bit system /
1561	#define BINMAPSHIFT 5
1562	#define BITSPERMAP (1U << BINMAPSHIFT)
1563	#define BINMAPSIZE (NBINS / BITSPERMAP)
1564
1565	#define idx2block(i) ((i) >> BINMAPSHIFT)
1566	#define idx2bit(i) ((1U << ((i) & ((1U << BINMAPSHIFT) - 1))))
1567
1568	#define mark_bin(m, i) ((m)->binmap[idx2block (i)] \|= idx2bit (i))
1569	#define unmark_bin(m, i) ((m)->binmap[idx2block (i)] &= ~(idx2bit (i)))
1570	#define get_binmap(m, i) ((m)->binmap[idx2block (i)] & idx2bit (i))
1571
1572	/*
1573	Fastbins
1574
1575	An array of lists holding recently freed small chunks. Fastbins
1576	are not doubly linked. It is faster to single-link them, and
1577	since chunks are never removed from the middles of these lists,
1578	double linking is not necessary. Also, unlike regular bins, they
1579	are not even processed in FIFO order (they use faster LIFO) since
1580	ordering doesn't much matter in the transient contexts in which
1581	fastbins are normally used.
1582
1583	Chunks in fastbins keep their inuse bit set, so they cannot
1584	be consolidated with other free chunks. malloc_consolidate
1585	releases all chunks in fastbins and consolidates them with
1586	other free chunks.
1587	*/
1588
1589	typedef struct malloc_chunk *mfastbinptr;
1590	#define fastbin(ar_ptr, idx) ((ar_ptr)->fastbinsY[idx])
1591
1592	/ offset 2 to use otherwise unindexable first 2 bins /
1593	#define fastbin_index(sz) \
1594	((((unsigned int) (sz)) >> (SIZE_SZ == 8 ? 4 : 3)) - 2)
1595
1596
1597	/ The maximum fastbin request size we support /
1598	#define MAX_FAST_SIZE (80 * SIZE_SZ / 4)
1599
1600	#define NFASTBINS (fastbin_index (request2size (MAX_FAST_SIZE)) + 1)
1601
1602	/*
1603	FASTBIN_CONSOLIDATION_THRESHOLD is the size of a chunk in free()
1604	that triggers automatic consolidation of possibly-surrounding
1605	fastbin chunks. This is a heuristic, so the exact value should not
1606	matter too much. It is defined at half the default trim threshold as a
1607	compromise heuristic to only attempt consolidation if it is likely
1608	to lead to trimming. However, it is not dynamically tunable, since
1609	consolidation reduces fragmentation surrounding large chunks even
1610	if trimming is not used.
1611	*/
1612
1613	#define FASTBIN_CONSOLIDATION_THRESHOLD (65536UL)
1614
1615	/*
1616	Since the lowest 2 bits in max_fast don't matter in size comparisons,
1617	they are used as flags.
1618	*/
1619
1620	/*
1621	FASTCHUNKS_BIT held in max_fast indicates that there are probably
1622	some fastbin chunks. It is set true on entering a chunk into any
1623	fastbin, and cleared only in malloc_consolidate.
1624
1625	The truth value is inverted so that have_fastchunks will be true
1626	upon startup (since statics are zero-filled), simplifying
1627	initialization checks.
1628	*/
1629
1630	#define FASTCHUNKS_BIT (1U)
1631
1632	#define have_fastchunks(M) (((M)->flags & FASTCHUNKS_BIT) == 0)
1633	#define clear_fastchunks(M) catomic_or (&(M)->flags, FASTCHUNKS_BIT)
1634	#define set_fastchunks(M) catomic_and (&(M)->flags, ~FASTCHUNKS_BIT)
1635
1636	/*
1637	NONCONTIGUOUS_BIT indicates that MORECORE does not return contiguous
1638	regions. Otherwise, contiguity is exploited in merging together,
1639	when possible, results from consecutive MORECORE calls.
1640
1641	The initial value comes from MORECORE_CONTIGUOUS, but is
1642	changed dynamically if mmap is ever used as an sbrk substitute.
1643	*/
1644
1645	#define NONCONTIGUOUS_BIT (2U)
1646
1647	#define contiguous(M) (((M)->flags & NONCONTIGUOUS_BIT) == 0)
1648	#define noncontiguous(M) (((M)->flags & NONCONTIGUOUS_BIT) != 0)
1649	#define set_noncontiguous(M) ((M)->flags \|= NONCONTIGUOUS_BIT)
1650	#define set_contiguous(M) ((M)->flags &= ~NONCONTIGUOUS_BIT)
1651
1652	/ ARENA_CORRUPTION_BIT is set if a memory corruption was detected on the*
1653	arena. Such an arena is no longer used to allocate chunks. Chunks
1654	allocated in that arena before detecting corruption are not freed. /*
1655
1656	#define ARENA_CORRUPTION_BIT (4U)
1657
1658	#define arena_is_corrupt(A) (((A)->flags & ARENA_CORRUPTION_BIT))
1659	#define set_arena_corrupt(A) ((A)->flags \|= ARENA_CORRUPTION_BIT)
1660
1661	/*
1662	Set value of max_fast.
1663	Use impossibly small value if 0.
1664	Precondition: there are no existing fastbin chunks.
1665	Setting the value clears fastchunk bit but preserves noncontiguous bit.
1666	*/
1667
1668	#define set_max_fast(s) \
1669	global_max_fast = (((s) == 0) \
1670	? SMALLBIN_WIDTH : ((s + SIZE_SZ) & ~MALLOC_ALIGN_MASK))
1671	#define get_max_fast() global_max_fast
1672
1673
1674	/*
1675	----------- Internal state representation and initialization -----------
1676	*/
1677
1678	struct malloc_state
1679	{
1680	/ Serialize access. /
1681	__libc_lock_define (, mutex);
1682
1683	/ Flags (formerly in max_fast). /
1684	int flags;
1685
1686	/ Fastbins /
1687	mfastbinptr fastbinsY[NFASTBINS];
1688
1689	/ Base of the topmost chunk -- not otherwise kept in a bin /
1690	mchunkptr top;
1691
1692	/ The remainder from the most recent split of a small request /
1693	mchunkptr last_remainder;
1694
1695	/ Normal bins packed as described above /
1696	mchunkptr bins[NBINS * `2` - `2`];
1697
1698	/ Bitmap of bins /
1699	unsigned int binmap[BINMAPSIZE];
1700
1701	/ Linked list /
1702	struct malloc_state *next;
1703
1704	/ Linked list for free arenas. Access to this field is serialized*
1705	by free_list_lock in arena.c. /*
1706	struct malloc_state *next_free;
1707
1708	/ Number of threads attached to this arena. 0 if the arena is on*
1709	the free list. Access to this field is serialized by
1710	free_list_lock in arena.c. /*
1711	INTERNAL_SIZE_T attached_threads;
1712
1713	/ Memory allocated from the system in this arena. /
1714	INTERNAL_SIZE_T system_mem;
1715	INTERNAL_SIZE_T max_system_mem;
1716	};
1717
1718	struct malloc_par
1719	{
1720	/ Tunable parameters /
1721	unsigned long trim_threshold;
1722	INTERNAL_SIZE_T top_pad;
1723	INTERNAL_SIZE_T mmap_threshold;
1724	INTERNAL_SIZE_T arena_test;
1725	INTERNAL_SIZE_T arena_max;
1726
1727	/ Memory map support /
1728	int n_mmaps;
1729	int n_mmaps_max;
1730	int max_n_mmaps;
1731	/ the mmap_threshold is dynamic, until the user sets*
1732	it manually, at which point we need to disable any
1733	dynamic behavior. /*
1734	int no_dyn_threshold;
1735
1736	/ Statistics /
1737	INTERNAL_SIZE_T mmapped_mem;
1738	INTERNAL_SIZE_T max_mmapped_mem;
1739
1740	/ First address handed out by MORECORE/sbrk. /
1741	char *sbrk_base;
1742
1743	#if USE_TCACHE
1744	/ Maximum number of buckets to use. /
1745	size_t tcache_bins;
1746	size_t tcache_max_bytes;
1747	/ Maximum number of chunks in each bucket. /
1748	size_t tcache_count;
1749	/ Maximum number of chunks to remove from the unsorted list, which*
1750	aren't used to prefill the cache. /*
1751	size_t tcache_unsorted_limit;
1752	#endif
1753	};
1754
1755	/ There are several instances of this struct ("arenas") in this*
1756	malloc. If you are adapting this malloc in a way that does NOT use
1757	a static or mmapped malloc_state, you MUST explicitly zero-fill it
1758	before using. This malloc relies on the property that malloc_state
1759	is initialized to all zeroes (as is true of C statics). /*
1760
1761	static struct malloc_state main_arena =
1762	{
1763	.mutex = _LIBC_LOCK_INITIALIZER,
1764	.next = &main_arena,
1765	.attached_threads = `1`
1766	};
1767
1768	/ These variables are used for undumping support. Chunked are marked*
1769	as using mmap, but we leave them alone if they fall into this
1770	range. NB: The chunk size for these chunks only includes the
1771	initial size field (of SIZE_SZ bytes), there is no trailing size
1772	field (unlike with regular mmapped chunks). /*
1773	static mchunkptr dumped_main_arena_start; / Inclusive. /
1774	static mchunkptr dumped_main_arena_end; / Exclusive. /
1775
1776	/ True if the pointer falls into the dumped arena. Use this after*
1777	chunk_is_mmapped indicates a chunk is mmapped. /*
1778	#define DUMPED_MAIN_ARENA_CHUNK(p) \
1779	((p) >= dumped_main_arena_start && (p) < dumped_main_arena_end)
1780
1781	/ There is only one instance of the malloc parameters. /
1782
1783	static struct malloc_par mp_ =
1784	{
1785	.top_pad = DEFAULT_TOP_PAD,
1786	.n_mmaps_max = DEFAULT_MMAP_MAX,
1787	.mmap_threshold = DEFAULT_MMAP_THRESHOLD,
1788	.trim_threshold = DEFAULT_TRIM_THRESHOLD,
1789	#define NARENAS_FROM_NCORES(n) ((n) * (sizeof (long) == 4 ? 2 : 8))
1790	.arena_test = NARENAS_FROM_NCORES (`1`)
1791	#if USE_TCACHE
1792	,
1793	.tcache_count = TCACHE_FILL_COUNT,
1794	.tcache_bins = TCACHE_MAX_BINS,
1795	.tcache_max_bytes = tidx2usize (TCACHE_MAX_BINS-`1`),
1796	.tcache_unsorted_limit = `0` / No limit. /
1797	#endif
1798	};
1799
1800	/ Maximum size of memory handled in fastbins. /
1801	static INTERNAL_SIZE_T global_max_fast;
1802
1803	/*
1804	Initialize a malloc_state struct.
1805
1806	This is called only from within malloc_consolidate, which needs
1807	be called in the same contexts anyway. It is never called directly
1808	outside of malloc_consolidate because some optimizing compilers try
1809	to inline it at all call points, which turns out not to be an
1810	optimization at all. (Inlining it in malloc_consolidate is fine though.)
1811	*/
1812
1813	static void
1814	malloc_init_state (mstate av)
1815	{
1816	int i;
1817	mbinptr bin;
1818
1819	/ Establish circular links for normal bins /
1820	for (i = `1`; i < NBINS; ++i)
1821	{
1822	bin = bin_at (av, i);
1823	bin->fd = bin->bk = bin;
1824	}
1825
1826	#if MORECORE_CONTIGUOUS
1827	if (av != &main_arena)
1828	#endif
1829	set_noncontiguous (av);
1830	if (av == &main_arena)
1831	set_max_fast (DEFAULT_MXFAST);
1832	av->flags \|= FASTCHUNKS_BIT;
1833
1834	av->top = initial_top (av);
1835	}
1836
1837	/*
1838	Other internal utilities operating on mstates
1839	*/
1840
1841	static void *sysmalloc (INTERNAL_SIZE_T, mstate);
1842	static int systrim (size_t, mstate);
1843	static void malloc_consolidate (mstate);
1844
1845
1846	/ -------------- Early definitions for debugging hooks ---------------- /
1847
1848	/ Define and initialize the hook variables. These weak definitions must*
1849	appear before any use of the variables in a function (arena.c uses one). /*
1850	#ifndef weak_variable
1851	/ In GNU libc we want the hook variables to be weak definitions to*
1852	avoid a problem with Emacs. /*
1853	# define weak_variable weak_function
1854	#endif
1855
1856	/ Forward declarations. /
1857	static void *malloc_hook_ini (size_t sz,
1858	const void *caller) __THROW;
1859	static void realloc_hook_ini (void* *ptr, size_t sz,
1860	const void *caller) __THROW;
1861	static void *memalign_hook_ini (size_t alignment, size_t sz,
1862	const void *caller) __THROW;
1863
1864	#if HAVE_MALLOC_INIT_HOOK
1865	void weak_variable (__malloc_initialize_hook) (void*) = NULL;
1866	compat_symbol (libc, __malloc_initialize_hook,
1867	__malloc_initialize_hook, GLIBC_2_0);
1868	#endif
1869
1870	void weak_variable (__free_hook) (void* *__ptr,
1871	const void *) = NULL;
1872	void weak_variable (__malloc_hook)
1873	(size_t __size, const void *) = malloc_hook_ini;
1874	void weak_variable (__realloc_hook)
1875	(void __ptr, size_t __size, const* void *)
1876	= realloc_hook_ini;
1877	void weak_variable (__memalign_hook)
1878	(size_t __alignment, size_t __size, const void *)
1879	= memalign_hook_ini;
1880	void weak_variable (__after_morecore_hook) (void*) = NULL;
1881
1882
1883	/ ---------------- Error behavior ------------------------------------ /
1884
1885	#ifndef DEFAULT_CHECK_ACTION
1886	# define DEFAULT_CHECK_ACTION 3
1887	#endif
1888
1889	static int check_action = DEFAULT_CHECK_ACTION;
1890
1891
1892	/ ------------------ Testing support ----------------------------------/
1893
1894	static int perturb_byte;
1895
1896	static void
1897	alloc_perturb (char *p, size_t n)
1898	{
1899	if (__glibc_unlikely (perturb_byte))
1900	memset (p, perturb_byte ^ `0xff`, n);
1901	}
1902
1903	static void
1904	free_perturb (char *p, size_t n)
1905	{
1906	if (__glibc_unlikely (perturb_byte))
1907	memset (p, perturb_byte, n);
1908	}
1909
1910
1911
1912	#include <stap-probe.h>
1913
1914	/ ------------------- Support for multiple arenas -------------------- /
1915	#include "arena.c"
1916
1917	/*
1918	Debugging support
1919
1920	These routines make a number of assertions about the states
1921	of data structures that should be true at all times. If any
1922	are not true, it's very likely that a user program has somehow
1923	trashed memory. (It's also possible that there is a coding error
1924	in malloc. In which case, please report it!)
1925	*/
1926
1927	#if !MALLOC_DEBUG
1928
1929	# define check_chunk(A, P)
1930	# define check_free_chunk(A, P)
1931	# define check_inuse_chunk(A, P)
1932	# define check_remalloced_chunk(A, P, N)
1933	# define check_malloced_chunk(A, P, N)
1934	# define check_malloc_state(A)
1935
1936	#else
1937
1938	# define check_chunk(A, P) do_check_chunk (A, P)
1939	# define check_free_chunk(A, P) do_check_free_chunk (A, P)
1940	# define check_inuse_chunk(A, P) do_check_inuse_chunk (A, P)
1941	# define check_remalloced_chunk(A, P, N) do_check_remalloced_chunk (A, P, N)
1942	# define check_malloced_chunk(A, P, N) do_check_malloced_chunk (A, P, N)
1943	# define check_malloc_state(A) do_check_malloc_state (A)
1944
1945	/*
1946	Properties of all chunks
1947	*/
1948
1949	static void
1950	do_check_chunk (mstate av, mchunkptr p)
1951	{
1952	unsigned long sz = chunksize (p);
1953	/ min and max possible addresses assuming contiguous allocation /
1954	char max_address = (char* *) (av->top) + chunksize (av->top);
1955	char *min_address = max_address - av->system_mem;
1956
1957	if (!chunk_is_mmapped (p))
1958	{
1959	/ Has legal address ... /
1960	if (p != av->top)
1961	{
1962	if (contiguous (av))
1963	{
1964	assert (((char *) p) >= min_address);
1965	assert (((char ) p + sz) <= ((char* *) (av->top)));
1966	}
1967	}
1968	else
1969	{
1970	/ top size is always at least MINSIZE /
1971	assert ((unsigned long) (sz) >= MINSIZE);
1972	/ top predecessor always marked inuse /
1973	assert (prev_inuse (p));
1974	}
1975	}
1976	else if (!DUMPED_MAIN_ARENA_CHUNK (p))
1977	{
1978	/ address is outside main heap /
1979	if (contiguous (av) && av->top != initial_top (av))
1980	{
1981	assert (((char ) p) < min_address \|\| ((char* *) p) >= max_address);
1982	}
1983	/ chunk is page-aligned /
1984	assert (((prev_size (p) + sz) & (GLRO (dl_pagesize) - `1`)) == `0`);
1985	/ mem is aligned /
1986	assert (aligned_OK (chunk2mem (p)));
1987	}
1988	}
1989
1990	/*
1991	Properties of free chunks
1992	*/
1993
1994	static void
1995	do_check_free_chunk (mstate av, mchunkptr p)
1996	{
1997	INTERNAL_SIZE_T sz = p->size & ~(PREV_INUSE \| NON_MAIN_ARENA);
1998	mchunkptr next = chunk_at_offset (p, sz);
1999
2000	do_check_chunk (av, p);
2001
2002	/ Chunk must claim to be free ... /
2003	assert (!inuse (p));
2004	assert (!chunk_is_mmapped (p));
2005
2006	/ Unless a special marker, must have OK fields /
2007	if ((unsigned long) (sz) >= MINSIZE)
2008	{
2009	assert ((sz & MALLOC_ALIGN_MASK) == `0`);
2010	assert (aligned_OK (chunk2mem (p)));
2011	/ ... matching footer field /
2012	assert (prev_size (p) == sz);
2013	/ ... and is fully consolidated /
2014	assert (prev_inuse (p));
2015	assert (next == av->top \|\| inuse (next));
2016
2017	/ ... and has minimally sane links /
2018	assert (p->fd->bk == p);
2019	assert (p->bk->fd == p);
2020	}
2021	else / markers are always of size SIZE_SZ /
2022	assert (sz == SIZE_SZ);
2023	}
2024
2025	/*
2026	Properties of inuse chunks
2027	*/
2028
2029	static void
2030	do_check_inuse_chunk (mstate av, mchunkptr p)
2031	{
2032	mchunkptr next;
2033
2034	do_check_chunk (av, p);
2035
2036	if (chunk_is_mmapped (p))
2037	return; / mmapped chunks have no next/prev /
2038
2039	/ Check whether it claims to be in use ... /
2040	assert (inuse (p));
2041
2042	next = next_chunk (p);
2043
2044	/ ... and is surrounded by OK chunks.*
2045	Since more things can be checked with free chunks than inuse ones,
2046	if an inuse chunk borders them and debug is on, it's worth doing them.
2047	*/
2048	if (!prev_inuse (p))
2049	{
2050	/ Note that we cannot even look at prev unless it is not inuse /
2051	mchunkptr prv = prev_chunk (p);
2052	assert (next_chunk (prv) == p);
2053	do_check_free_chunk (av, prv);
2054	}
2055
2056	if (next == av->top)
2057	{
2058	assert (prev_inuse (next));
2059	assert (chunksize (next) >= MINSIZE);
2060	}
2061	else if (!inuse (next))
2062	do_check_free_chunk (av, next);
2063	}
2064
2065	/*
2066	Properties of chunks recycled from fastbins
2067	*/
2068
2069	static void
2070	do_check_remalloced_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T s)
2071	{
2072	INTERNAL_SIZE_T sz = p->size & ~(PREV_INUSE \| NON_MAIN_ARENA);
2073
2074	if (!chunk_is_mmapped (p))
2075	{
2076	assert (av == arena_for_chunk (p));
2077	if (chunk_main_arena (p))
2078	assert (av == &main_arena);
2079	else
2080	assert (av != &main_arena);
2081	}
2082
2083	do_check_inuse_chunk (av, p);
2084
2085	/ Legal size ... /
2086	assert ((sz & MALLOC_ALIGN_MASK) == `0`);
2087	assert ((unsigned long) (sz) >= MINSIZE);
2088	/ ... and alignment /
2089	assert (aligned_OK (chunk2mem (p)));
2090	/ chunk is less than MINSIZE more than request /
2091	assert ((long) (sz) - (long) (s) >= `0`);
2092	assert ((long) (sz) - (long) (s + MINSIZE) < `0`);
2093	}
2094
2095	/*
2096	Properties of nonrecycled chunks at the point they are malloced
2097	*/
2098
2099	static void
2100	do_check_malloced_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T s)
2101	{
2102	/ same as recycled case ... /
2103	do_check_remalloced_chunk (av, p, s);
2104
2105	/*
2106	... plus, must obey implementation invariant that prev_inuse is
2107	always true of any allocated chunk; i.e., that each allocated
2108	chunk borders either a previously allocated and still in-use
2109	chunk, or the base of its memory arena. This is ensured
2110	by making all allocations from the `lowest' part of any found
2111	chunk. This does not necessarily hold however for chunks
2112	recycled via fastbins.
2113	*/
2114
2115	assert (prev_inuse (p));
2116	}
2117
2118
2119	/*
2120	Properties of malloc_state.
2121
2122	This may be useful for debugging malloc, as well as detecting user
2123	programmer errors that somehow write into malloc_state.
2124
2125	If you are extending or experimenting with this malloc, you can
2126	probably figure out how to hack this routine to print out or
2127	display chunk addresses, sizes, bins, and other instrumentation.
2128	*/
2129
2130	static void
2131	do_check_malloc_state (mstate av)
2132	{
2133	int i;
2134	mchunkptr p;
2135	mchunkptr q;
2136	mbinptr b;
2137	unsigned int idx;
2138	INTERNAL_SIZE_T size;
2139	unsigned long total = `0`;
2140	int max_fast_bin;
2141
2142	/ internal size_t must be no wider than pointer type /
2143	assert (sizeof (INTERNAL_SIZE_T) <= sizeof (char *));
2144
2145	/ alignment is a power of 2 /
2146	assert ((MALLOC_ALIGNMENT & (MALLOC_ALIGNMENT - `1`)) == `0`);
2147
2148	/ cannot run remaining checks until fully initialized /
2149	if (av->top == `0` \|\| av->top == initial_top (av))
2150	return;
2151
2152	/ pagesize is a power of 2 /
2153	assert (powerof2(GLRO (dl_pagesize)));
2154
2155	/ A contiguous main_arena is consistent with sbrk_base. /
2156	if (av == &main_arena && contiguous (av))
2157	assert ((char *) mp_.sbrk_base + av->system_mem ==
2158	(char *) av->top + chunksize (av->top));
2159
2160	/ properties of fastbins /
2161
2162	/ max_fast is in allowed range /
2163	assert ((get_max_fast () & ~`1`) <= request2size (MAX_FAST_SIZE));
2164
2165	max_fast_bin = fastbin_index (get_max_fast ());
2166
2167	for (i = `0`; i < NFASTBINS; ++i)
2168	{
2169	p = fastbin (av, i);
2170
2171	/ The following test can only be performed for the main arena.*
2172	While mallopt calls malloc_consolidate to get rid of all fast
2173	bins (especially those larger than the new maximum) this does
2174	only happen for the main arena. Trying to do this for any
2175	other arena would mean those arenas have to be locked and
2176	malloc_consolidate be called for them. This is excessive. And
2177	even if this is acceptable to somebody it still cannot solve
2178	the problem completely since if the arena is locked a
2179	concurrent malloc call might create a new arena which then
2180	could use the newly invalid fast bins. /*
2181
2182	/ all bins past max_fast are empty /
2183	if (av == &main_arena && i > max_fast_bin)
2184	assert (p == `0`);
2185
2186	while (p != `0`)
2187	{
2188	/ each chunk claims to be inuse /
2189	do_check_inuse_chunk (av, p);
2190	total += chunksize (p);
2191	/ chunk belongs in this bin /
2192	assert (fastbin_index (chunksize (p)) == i);
2193	p = p->fd;
2194	}
2195	}
2196
2197	if (total != `0`)
2198	assert (have_fastchunks (av));
2199	else if (!have_fastchunks (av))
2200	assert (total == `0`);
2201
2202	/ check normal bins /
2203	for (i = `1`; i < NBINS; ++i)
2204	{
2205	b = bin_at (av, i);
2206
2207	/ binmap is accurate (except for bin 1 == unsorted_chunks) /
2208	if (i >= `2`)
2209	{
2210	unsigned int binbit = get_binmap (av, i);
2211	int empty = last (b) == b;
2212	if (!binbit)
2213	assert (empty);
2214	else if (!empty)
2215	assert (binbit);
2216	}
2217
2218	for (p = last (b); p != b; p = p->bk)
2219	{
2220	/ each chunk claims to be free /
2221	do_check_free_chunk (av, p);
2222	size = chunksize (p);
2223	total += size;
2224	if (i >= `2`)
2225	{
2226	/ chunk belongs in bin /
2227	idx = bin_index (size);
2228	assert (idx == i);
2229	/ lists are sorted /
2230	assert (p->bk == b \|\|
2231	(unsigned long) chunksize (p->bk) >= (unsigned long) chunksize (p));
2232
2233	if (!in_smallbin_range (size))
2234	{
2235	if (p->fd_nextsize != NULL)
2236	{
2237	if (p->fd_nextsize == p)
2238	assert (p->bk_nextsize == p);
2239	else
2240	{
2241	if (p->fd_nextsize == first (b))
2242	assert (chunksize (p) < chunksize (p->fd_nextsize));
2243	else
2244	assert (chunksize (p) > chunksize (p->fd_nextsize));
2245
2246	if (p == first (b))
2247	assert (chunksize (p) > chunksize (p->bk_nextsize));
2248	else
2249	assert (chunksize (p) < chunksize (p->bk_nextsize));
2250	}
2251	}
2252	else
2253	assert (p->bk_nextsize == NULL);
2254	}
2255	}
2256	else if (!in_smallbin_range (size))
2257	assert (p->fd_nextsize == NULL && p->bk_nextsize == NULL);
2258	/ chunk is followed by a legal chain of inuse chunks /
2259	for (q = next_chunk (p);
2260	(q != av->top && inuse (q) &&
2261	(unsigned long) (chunksize (q)) >= MINSIZE);
2262	q = next_chunk (q))
2263	do_check_inuse_chunk (av, q);
2264	}
2265	}
2266
2267	/ top chunk is OK /
2268	check_chunk (av, av->top);
2269	}
2270	#endif
2271
2272
2273	/ ----------------- Support for debugging hooks -------------------- /
2274	#include "hooks.c"
2275
2276
2277	/ ----------- Routines dealing with system allocation -------------- /
2278
2279	/*
2280	sysmalloc handles malloc cases requiring more memory from the system.
2281	On entry, it is assumed that av->top does not have enough
2282	space to service request for nb bytes, thus requiring that av->top
2283	be extended or replaced.
2284	*/
2285
2286	static void *
2287	sysmalloc (INTERNAL_SIZE_T nb, mstate av)
2288	{
2289	mchunkptr old_top; / incoming value of av->top /
2290	INTERNAL_SIZE_T old_size; / its size /
2291	char old_end; /* its end address /
2292
2293	long size; / arg to first MORECORE or mmap call /
2294	char brk; /* return value from MORECORE /
2295
2296	long correction; / arg to 2nd MORECORE call /
2297	char snd_brk; /* 2nd return val /
2298
2299	INTERNAL_SIZE_T front_misalign; / unusable bytes at front of new space /
2300	INTERNAL_SIZE_T end_misalign; / partial page left at end of new space /
2301	char aligned_brk; /* aligned offset into brk /
2302
2303	mchunkptr p; / the allocated/returned chunk /
2304	mchunkptr remainder; / remainder from allocation /
2305	unsigned long remainder_size; / its size /
2306
2307
2308	size_t pagesize = GLRO (dl_pagesize);
2309	bool tried_mmap = false;
2310
2311
2312	/*
2313	If have mmap, and the request size meets the mmap threshold, and
2314	the system supports mmap, and there are few enough currently
2315	allocated mmapped regions, try to directly map this request
2316	rather than expanding top.
2317	*/
2318
2319	if (av == NULL
2320	\|\| ((unsigned long) (nb) >= (unsigned long) (mp_.mmap_threshold)
2321	&& (mp_.n_mmaps < mp_.n_mmaps_max)))
2322	{
2323	char mm; /* return value from mmap call/
2324
2325	try_mmap:
2326	/*
2327	Round up size to nearest page. For mmapped chunks, the overhead
2328	is one SIZE_SZ unit larger than for normal chunks, because there
2329	is no following chunk whose prev_size field could be used.
2330
2331	See the front_misalign handling below, for glibc there is no
2332	need for further alignments unless we have have high alignment.
2333	*/
2334	if (MALLOC_ALIGNMENT == `2` * SIZE_SZ)
2335	size = ALIGN_UP (nb + SIZE_SZ, pagesize);
2336	else
2337	size = ALIGN_UP (nb + SIZE_SZ + MALLOC_ALIGN_MASK, pagesize);
2338	tried_mmap = true;
2339
2340	/ Don't try if size wraps around 0 /
2341	if ((unsigned long) (size) > (unsigned long) (nb))
2342	{
2343	mm = (char *) (MMAP (`0`, size, PROT_READ \| PROT_WRITE, `0`));
2344
2345	if (mm != MAP_FAILED)
2346	{
2347	/*
2348	The offset to the start of the mmapped region is stored
2349	in the prev_size field of the chunk. This allows us to adjust
2350	returned start address to meet alignment requirements here
2351	and in memalign(), and still be able to compute proper
2352	address argument for later munmap in free() and realloc().
2353	*/
2354
2355	if (MALLOC_ALIGNMENT == `2` * SIZE_SZ)
2356	{
2357	/ For glibc, chunk2mem increases the address by 2SIZE_SZ and
2358	MALLOC_ALIGN_MASK is 2SIZE_SZ-1. Each mmap'ed area is page*
2359	aligned and therefore definitely MALLOC_ALIGN_MASK-aligned. /*
2360	assert (((INTERNAL_SIZE_T) chunk2mem (mm) & MALLOC_ALIGN_MASK) == `0`);
2361	front_misalign = `0`;
2362	}
2363	else
2364	front_misalign = (INTERNAL_SIZE_T) chunk2mem (mm) & MALLOC_ALIGN_MASK;
2365	if (front_misalign > `0`)
2366	{
2367	correction = MALLOC_ALIGNMENT - front_misalign;
2368	p = (mchunkptr) (mm + correction);
2369	set_prev_size (p, correction);
2370	set_head (p, (size - correction) \| IS_MMAPPED);
2371	}
2372	else
2373	{
2374	p = (mchunkptr) mm;
2375	set_prev_size (p, `0`);
2376	set_head (p, size \| IS_MMAPPED);
2377	}
2378
2379	/ update statistics /
2380
2381	int new = atomic_exchange_and_add (&mp_.n_mmaps, `1`) + `1`;
2382	atomic_max (&mp_.max_n_mmaps, new);
2383
2384	unsigned long sum;
2385	sum = atomic_exchange_and_add (&mp_.mmapped_mem, size) + size;
2386	atomic_max (&mp_.max_mmapped_mem, sum);
2387
2388	check_chunk (av, p);
2389
2390	return chunk2mem (p);
2391	}
2392	}
2393	}
2394
2395	/ There are no usable arenas and mmap also failed. /
2396	if (av == NULL)
2397	return `0`;
2398
2399	/ Record incoming configuration of top /
2400
2401	old_top = av->top;
2402	old_size = chunksize (old_top);
2403	old_end = (char *) (chunk_at_offset (old_top, old_size));
2404
2405	brk = snd_brk = (char *) (MORECORE_FAILURE);
2406
2407	/*
2408	If not the first time through, we require old_size to be
2409	at least MINSIZE and to have prev_inuse set.
2410	*/
2411
2412	assert ((old_top == initial_top (av) && old_size == `0`) \|\|
2413	((unsigned long) (old_size) >= MINSIZE &&
2414	prev_inuse (old_top) &&
2415	((unsigned long) old_end & (pagesize - `1`)) == `0`));
2416
2417	/ Precondition: not enough current space to satisfy nb request /
2418	assert ((unsigned long) (old_size) < (unsigned long) (nb + MINSIZE));
2419
2420
2421	if (av != &main_arena)
2422	{
2423	heap_info old_heap, heap;
2424	size_t old_heap_size;
2425
2426	/ First try to extend the current heap. /
2427	old_heap = heap_for_ptr (old_top);
2428	old_heap_size = old_heap->size;
2429	if ((long) (MINSIZE + nb - old_size) > `0`
2430	&& grow_heap (old_heap, MINSIZE + nb - old_size) == `0`)
2431	{
2432	av->system_mem += old_heap->size - old_heap_size;
2433	set_head (old_top, (((char ) old_heap + old_heap->size) - (char* *) old_top)
2434	\| PREV_INUSE);
2435	}
2436	else if ((heap = new_heap (nb + (MINSIZE + sizeof (*heap)), mp_.top_pad)))
2437	{
2438	/ Use a newly allocated heap. /
2439	heap->ar_ptr = av;
2440	heap->prev = old_heap;
2441	av->system_mem += heap->size;
2442	/ Set up the new top. /
2443	top (av) = chunk_at_offset (heap, sizeof (*heap));
2444	set_head (top (av), (heap->size - sizeof (*heap)) \| PREV_INUSE);
2445
2446	/ Setup fencepost and free the old top chunk with a multiple of*
2447	MALLOC_ALIGNMENT in size. /*
2448	/ The fencepost takes at least MINSIZE bytes, because it might*
2449	become the top chunk again later. Note that a footer is set
2450	up, too, although the chunk is marked in use. /*
2451	old_size = (old_size - MINSIZE) & ~MALLOC_ALIGN_MASK;
2452	set_head (chunk_at_offset (old_top, old_size + `2` * SIZE_SZ), `0` \| PREV_INUSE);
2453	if (old_size >= MINSIZE)
2454	{
2455	set_head (chunk_at_offset (old_top, old_size), (`2` * SIZE_SZ) \| PREV_INUSE);
2456	set_foot (chunk_at_offset (old_top, old_size), (`2` * SIZE_SZ));
2457	set_head (old_top, old_size \| PREV_INUSE \| NON_MAIN_ARENA);
2458	_int_free (av, old_top, `1`);
2459	}
2460	else
2461	{
2462	set_head (old_top, (old_size + `2` * SIZE_SZ) \| PREV_INUSE);
2463	set_foot (old_top, (old_size + `2` * SIZE_SZ));
2464	}
2465	}
2466	else if (!tried_mmap)
2467	/ We can at least try to use to mmap memory. /
2468	goto try_mmap;
2469	}
2470	else / av == main_arena /
2471
2472
2473	{ / Request enough space for nb + pad + overhead /
2474	size = nb + mp_.top_pad + MINSIZE;
2475
2476	/*
2477	If contiguous, we can subtract out existing space that we hope to
2478	combine with new space. We add it back later only if
2479	we don't actually get contiguous space.
2480	*/
2481
2482	if (contiguous (av))
2483	size -= old_size;
2484
2485	/*
2486	Round to a multiple of page size.
2487	If MORECORE is not contiguous, this ensures that we only call it
2488	with whole-page arguments. And if MORECORE is contiguous and
2489	this is not first time through, this preserves page-alignment of
2490	previous calls. Otherwise, we correct to page-align below.
2491	*/
2492
2493	size = ALIGN_UP (size, pagesize);
2494
2495	/*
2496	Don't try to call MORECORE if argument is so big as to appear
2497	negative. Note that since mmap takes size_t arg, it may succeed
2498	below even if we cannot call MORECORE.
2499	*/
2500
2501	if (size > `0`)
2502	{
2503	brk = (char *) (MORECORE (size));
2504	LIBC_PROBE (memory_sbrk_more, `2`, brk, size);
2505	}
2506
2507	if (brk != (char *) (MORECORE_FAILURE))
2508	{
2509	/ Call the `morecore' hook if necessary. /
2510	void (hook) (void*) = atomic_forced_read (__after_morecore_hook);
2511	if (__builtin_expect (hook != NULL, `0`))
2512	(*hook)();
2513	}
2514	else
2515	{
2516	/*
2517	If have mmap, try using it as a backup when MORECORE fails or
2518	cannot be used. This is worth doing on systems that have "holes" in
2519	address space, so sbrk cannot extend to give contiguous space, but
2520	space is available elsewhere. Note that we ignore mmap max count
2521	and threshold limits, since the space will not be used as a
2522	segregated mmap region.
2523	*/
2524
2525	/ Cannot merge with old top, so add its size back in /
2526	if (contiguous (av))
2527	size = ALIGN_UP (size + old_size, pagesize);
2528
2529	/ If we are relying on mmap as backup, then use larger units /
2530	if ((unsigned long) (size) < (unsigned long) (MMAP_AS_MORECORE_SIZE))
2531	size = MMAP_AS_MORECORE_SIZE;
2532
2533	/ Don't try if size wraps around 0 /
2534	if ((unsigned long) (size) > (unsigned long) (nb))
2535	{
2536	char mbrk = (char* *) (MMAP (`0`, size, PROT_READ \| PROT_WRITE, `0`));
2537
2538	if (mbrk != MAP_FAILED)
2539	{
2540	/ We do not need, and cannot use, another sbrk call to find end /
2541	brk = mbrk;
2542	snd_brk = brk + size;
2543
2544	/*
2545	Record that we no longer have a contiguous sbrk region.
2546	After the first time mmap is used as backup, we do not
2547	ever rely on contiguous space since this could incorrectly
2548	bridge regions.
2549	*/
2550	set_noncontiguous (av);
2551	}
2552	}
2553	}
2554
2555	if (brk != (char *) (MORECORE_FAILURE))
2556	{
2557	if (mp_.sbrk_base == `0`)
2558	mp_.sbrk_base = brk;
2559	av->system_mem += size;
2560
2561	/*
2562	If MORECORE extends previous space, we can likewise extend top size.
2563	*/
2564
2565	if (brk == old_end && snd_brk == (char *) (MORECORE_FAILURE))
2566	set_head (old_top, (size + old_size) \| PREV_INUSE);
2567
2568	else if (contiguous (av) && old_size && brk < old_end)
2569	{
2570	/ Oops! Someone else killed our space.. Can't touch anything. /
2571	malloc_printerr (`3`, "break adjusted to free malloc space", brk,
2572	av);
2573	}
2574
2575	/*
2576	Otherwise, make adjustments:
2577
2578	* If the first time through or noncontiguous, we need to call sbrk
2579	just to find out where the end of memory lies.
2580
2581	* We need to ensure that all returned chunks from malloc will meet
2582	MALLOC_ALIGNMENT
2583
2584	* If there was an intervening foreign sbrk, we need to adjust sbrk
2585	request size to account for fact that we will not be able to
2586	combine new space with existing space in old_top.
2587
2588	* Almost all systems internally allocate whole pages at a time, in
2589	which case we might as well use the whole last page of request.
2590	So we allocate enough more memory to hit a page boundary now,
2591	which in turn causes future contiguous calls to page-align.
2592	*/
2593
2594	else
2595	{
2596	front_misalign = `0`;
2597	end_misalign = `0`;
2598	correction = `0`;
2599	aligned_brk = brk;
2600
2601	/ handle contiguous cases /
2602	if (contiguous (av))
2603	{
2604	/ Count foreign sbrk as system_mem. /
2605	if (old_size)
2606	av->system_mem += brk - old_end;
2607
2608	/ Guarantee alignment of first new chunk made from this space /
2609
2610	front_misalign = (INTERNAL_SIZE_T) chunk2mem (brk) & MALLOC_ALIGN_MASK;
2611	if (front_misalign > `0`)
2612	{
2613	/*
2614	Skip over some bytes to arrive at an aligned position.
2615	We don't need to specially mark these wasted front bytes.
2616	They will never be accessed anyway because
2617	prev_inuse of av->top (and any chunk created from its start)
2618	is always true after initialization.
2619	*/
2620
2621	correction = MALLOC_ALIGNMENT - front_misalign;
2622	aligned_brk += correction;
2623	}
2624
2625	/*
2626	If this isn't adjacent to existing space, then we will not
2627	be able to merge with old_top space, so must add to 2nd request.
2628	*/
2629
2630	correction += old_size;
2631
2632	/ Extend the end address to hit a page boundary /
2633	end_misalign = (INTERNAL_SIZE_T) (brk + size + correction);
2634	correction += (ALIGN_UP (end_misalign, pagesize)) - end_misalign;
2635
2636	assert (correction >= `0`);
2637	snd_brk = (char *) (MORECORE (correction));
2638
2639	/*
2640	If can't allocate correction, try to at least find out current
2641	brk. It might be enough to proceed without failing.
2642
2643	Note that if second sbrk did NOT fail, we assume that space
2644	is contiguous with first sbrk. This is a safe assumption unless
2645	program is multithreaded but doesn't use locks and a foreign sbrk
2646	occurred between our first and second calls.
2647	*/
2648
2649	if (snd_brk == (char *) (MORECORE_FAILURE))
2650	{
2651	correction = `0`;
2652	snd_brk = (char *) (MORECORE (`0`));
2653	}
2654	else
2655	{
2656	/ Call the `morecore' hook if necessary. /
2657	void (hook) (void*) = atomic_forced_read (__after_morecore_hook);
2658	if (__builtin_expect (hook != NULL, `0`))
2659	(*hook)();
2660	}
2661	}
2662
2663	/ handle non-contiguous cases /
2664	else
2665	{
2666	if (MALLOC_ALIGNMENT == `2` * SIZE_SZ)
2667	/ MORECORE/mmap must correctly align /
2668	assert (((unsigned long) chunk2mem (brk) & MALLOC_ALIGN_MASK) == `0`);
2669	else
2670	{
2671	front_misalign = (INTERNAL_SIZE_T) chunk2mem (brk) & MALLOC_ALIGN_MASK;
2672	if (front_misalign > `0`)
2673	{
2674	/*
2675	Skip over some bytes to arrive at an aligned position.
2676	We don't need to specially mark these wasted front bytes.
2677	They will never be accessed anyway because
2678	prev_inuse of av->top (and any chunk created from its start)
2679	is always true after initialization.
2680	*/
2681
2682	aligned_brk += MALLOC_ALIGNMENT - front_misalign;
2683	}
2684	}
2685
2686	/ Find out current end of memory /
2687	if (snd_brk == (char *) (MORECORE_FAILURE))
2688	{
2689	snd_brk = (char *) (MORECORE (`0`));
2690	}
2691	}
2692
2693	/ Adjust top based on results of second sbrk /
2694	if (snd_brk != (char *) (MORECORE_FAILURE))
2695	{
2696	av->top = (mchunkptr) aligned_brk;
2697	set_head (av->top, (snd_brk - aligned_brk + correction) \| PREV_INUSE);
2698	av->system_mem += correction;
2699
2700	/*
2701	If not the first time through, we either have a
2702	gap due to foreign sbrk or a non-contiguous region. Insert a
2703	double fencepost at old_top to prevent consolidation with space
2704	we don't own. These fenceposts are artificial chunks that are
2705	marked as inuse and are in any case too small to use. We need
2706	two to make sizes and alignments work out.
2707	*/
2708
2709	if (old_size != `0`)
2710	{
2711	/*
2712	Shrink old_top to insert fenceposts, keeping size a
2713	multiple of MALLOC_ALIGNMENT. We know there is at least
2714	enough space in old_top to do this.
2715	*/
2716	old_size = (old_size - `4` * SIZE_SZ) & ~MALLOC_ALIGN_MASK;
2717	set_head (old_top, old_size \| PREV_INUSE);
2718
2719	/*
2720	Note that the following assignments completely overwrite
2721	old_top when old_size was previously MINSIZE. This is
2722	intentional. We need the fencepost, even if old_top otherwise gets
2723	lost.
2724	*/
2725	set_head (chunk_at_offset (old_top, old_size),
2726	(`2` * SIZE_SZ) \| PREV_INUSE);
2727	set_head (chunk_at_offset (old_top, old_size + `2` * SIZE_SZ),
2728	(`2` * SIZE_SZ) \| PREV_INUSE);
2729
2730	/ If possible, release the rest. /
2731	if (old_size >= MINSIZE)
2732	{
2733	_int_free (av, old_top, `1`);
2734	}
2735	}
2736	}
2737	}
2738	}
2739	} / if (av != &main_arena) /
2740
2741	if ((unsigned long) av->system_mem > (unsigned long) (av->max_system_mem))
2742	av->max_system_mem = av->system_mem;
2743	check_malloc_state (av);
2744
2745	/ finally, do the allocation /
2746	p = av->top;
2747	size = chunksize (p);
2748
2749	/ check that one of the above allocation paths succeeded /
2750	if ((unsigned long) (size) >= (unsigned long) (nb + MINSIZE))
2751	{
2752	remainder_size = size - nb;
2753	remainder = chunk_at_offset (p, nb);
2754	av->top = remainder;
2755	set_head (p, nb \| PREV_INUSE \| (av != &main_arena ? NON_MAIN_ARENA : `0`));
2756	set_head (remainder, remainder_size \| PREV_INUSE);
2757	check_malloced_chunk (av, p, nb);
2758	return chunk2mem (p);
2759	}
2760
2761	/ catch all failure paths /
2762	__set_errno (ENOMEM);
2763	return `0`;
2764	}
2765
2766
2767	/*
2768	systrim is an inverse of sorts to sysmalloc. It gives memory back
2769	to the system (via negative arguments to sbrk) if there is unused
2770	memory at the `high' end of the malloc pool. It is called
2771	automatically by free() when top space exceeds the trim
2772	threshold. It is also called by the public malloc_trim routine. It
2773	returns 1 if it actually released any memory, else 0.
2774	*/
2775
2776	static int
2777	systrim (size_t pad, mstate av)
2778	{
2779	long top_size; / Amount of top-most memory /
2780	long extra; / Amount to release /
2781	long released; / Amount actually released /
2782	char current_brk; /* address returned by pre-check sbrk call /
2783	char new_brk; /* address returned by post-check sbrk call /
2784	size_t pagesize;
2785	long top_area;
2786
2787	pagesize = GLRO (dl_pagesize);
2788	top_size = chunksize (av->top);
2789
2790	top_area = top_size - MINSIZE - `1`;
2791	if (top_area <= pad)
2792	return `0`;
2793
2794	/ Release in pagesize units and round down to the nearest page. /
2795	extra = ALIGN_DOWN(top_area - pad, pagesize);
2796
2797	if (extra == `0`)
2798	return `0`;
2799
2800	/*
2801	Only proceed if end of memory is where we last set it.
2802	This avoids problems if there were foreign sbrk calls.
2803	*/
2804	current_brk = (char *) (MORECORE (`0`));
2805	if (current_brk == (char *) (av->top) + top_size)
2806	{
2807	/*
2808	Attempt to release memory. We ignore MORECORE return value,
2809	and instead call again to find out where new end of memory is.
2810	This avoids problems if first call releases less than we asked,
2811	of if failure somehow altered brk value. (We could still
2812	encounter problems if it altered brk in some very bad way,
2813	but the only thing we can do is adjust anyway, which will cause
2814	some downstream failure.)
2815	*/
2816
2817	MORECORE (-extra);
2818	/ Call the `morecore' hook if necessary. /
2819	void (hook) (void*) = atomic_forced_read (__after_morecore_hook);
2820	if (__builtin_expect (hook != NULL, `0`))
2821	(*hook)();
2822	new_brk = (char *) (MORECORE (`0`));
2823
2824	LIBC_PROBE (memory_sbrk_less, `2`, new_brk, extra);
2825
2826	if (new_brk != (char *) MORECORE_FAILURE)
2827	{
2828	released = (long) (current_brk - new_brk);
2829
2830	if (released != `0`)
2831	{
2832	/ Success. Adjust top. /
2833	av->system_mem -= released;
2834	set_head (av->top, (top_size - released) \| PREV_INUSE);
2835	check_malloc_state (av);
2836	return `1`;
2837	}
2838	}
2839	}
2840	return `0`;
2841	}
2842
2843	static void
2844	internal_function
2845	munmap_chunk (mchunkptr p)
2846	{
2847	INTERNAL_SIZE_T size = chunksize (p);
2848
2849	assert (chunk_is_mmapped (p));
2850
2851	/ Do nothing if the chunk is a faked mmapped chunk in the dumped*
2852	main arena. We never free this memory. /*
2853	if (DUMPED_MAIN_ARENA_CHUNK (p))
2854	return;
2855
2856	uintptr_t block = (uintptr_t) p - prev_size (p);
2857	size_t total_size = prev_size (p) + size;
2858	/ Unfortunately we have to do the compilers job by hand here. Normally*
2859	we would test BLOCK and TOTAL-SIZE separately for compliance with the
2860	page size. But gcc does not recognize the optimization possibility
2861	(in the moment at least) so we combine the two values into one before
2862	the bit test. /*
2863	if (__builtin_expect (((block \| total_size) & (GLRO (dl_pagesize) - `1`)) != `0`, `0`))
2864	{
2865	malloc_printerr (check_action, "munmap_chunk(): invalid pointer",
2866	chunk2mem (p), NULL);
2867	return;
2868	}
2869
2870	atomic_decrement (&mp_.n_mmaps);
2871	atomic_add (&mp_.mmapped_mem, -total_size);
2872
2873	/ If munmap failed the process virtual memory address space is in a*
2874	bad shape. Just leave the block hanging around, the process will
2875	terminate shortly anyway since not much can be done. /*
2876	__munmap ((char *) block, total_size);
2877	}
2878
2879	#if HAVE_MREMAP
2880
2881	static mchunkptr
2882	internal_function
2883	mremap_chunk (mchunkptr p, size_t new_size)
2884	{
2885	size_t pagesize = GLRO (dl_pagesize);
2886	INTERNAL_SIZE_T offset = prev_size (p);
2887	INTERNAL_SIZE_T size = chunksize (p);
2888	char *cp;
2889
2890	assert (chunk_is_mmapped (p));
2891	assert (((size + offset) & (GLRO (dl_pagesize) - `1`)) == `0`);
2892
2893	/ Note the extra SIZE_SZ overhead as in mmap_chunk(). /
2894	new_size = ALIGN_UP (new_size + offset + SIZE_SZ, pagesize);
2895
2896	/ No need to remap if the number of pages does not change. /
2897	if (size + offset == new_size)
2898	return p;
2899
2900	cp = (char ) __mremap ((char* *) p - offset, size + offset, new_size,
2901	MREMAP_MAYMOVE);
2902
2903	if (cp == MAP_FAILED)
2904	return `0`;
2905
2906	p = (mchunkptr) (cp + offset);
2907
2908	assert (aligned_OK (chunk2mem (p)));
2909
2910	assert (prev_size (p) == offset);
2911	set_head (p, (new_size - offset) \| IS_MMAPPED);
2912
2913	INTERNAL_SIZE_T new;
2914	new = atomic_exchange_and_add (&mp_.mmapped_mem, new_size - size - offset)
2915	+ new_size - size - offset;
2916	atomic_max (&mp_.max_mmapped_mem, new);
2917	return p;
2918	}
2919	#endif /* HAVE_MREMAP */
2920
2921	/------------------------ Public wrappers. --------------------------------/
2922
2923	#if USE_TCACHE
2924
2925	/ We overlay this structure on the user-data portion of a chunk when*
2926	the chunk is stored in the per-thread cache. /*
2927	typedef struct tcache_entry
2928	{
2929	struct tcache_entry *next;
2930	} tcache_entry;
2931
2932	/ There is one of these for each thread, which contains the*
2933	per-thread cache (hence "tcache_perthread_struct"). Keeping
2934	overall size low is mildly important. Note that COUNTS and ENTRIES
2935	are redundant (we could have just counted the linked list each
2936	time), this is for performance reasons. /*
2937	typedef struct tcache_perthread_struct
2938	{
2939	char counts[TCACHE_MAX_BINS];
2940	tcache_entry *entries[TCACHE_MAX_BINS];
2941	} tcache_perthread_struct;
2942
2943	static __thread char tcache_shutting_down = `0`;
2944	static __thread tcache_perthread_struct *tcache = NULL;
2945
2946	/ Caller must ensure that we know tc_idx is valid and there's room*
2947	for more chunks. /*
2948	static void
2949	tcache_put (mchunkptr chunk, size_t tc_idx)
2950	{
2951	tcache_entry e = (tcache_entry ) chunk2mem (chunk);
2952	assert (tc_idx < TCACHE_MAX_BINS);
2953	e->next = tcache->entries[tc_idx];
2954	tcache->entries[tc_idx] = e;
2955	++(tcache->counts[tc_idx]);
2956	}
2957
2958	/ Caller must ensure that we know tc_idx is valid and there's*
2959	available chunks to remove. /*
2960	static void *
2961	tcache_get (size_t tc_idx)
2962	{
2963	tcache_entry *e = tcache->entries[tc_idx];
2964	assert (tc_idx < TCACHE_MAX_BINS);
2965	assert (tcache->entries[tc_idx] > `0`);
2966	tcache->entries[tc_idx] = e->next;
2967	--(tcache->counts[tc_idx]);
2968	return (void *) e;
2969	}
2970
2971	static void __attribute__ ((section ("__libc_thread_freeres_fn")))
2972	tcache_thread_freeres (void)
2973	{
2974	int i;
2975	tcache_perthread_struct *tcache_tmp = tcache;
2976
2977	if (!tcache)
2978	return;
2979
2980	tcache = NULL;
2981
2982	for (i = `0`; i < TCACHE_MAX_BINS; ++i)
2983	{
2984	while (tcache_tmp->entries[i])
2985	{
2986	tcache_entry *e = tcache_tmp->entries[i];
2987	tcache_tmp->entries[i] = e->next;
2988	__libc_free (e);
2989	}
2990	}
2991
2992	__libc_free (tcache_tmp);
2993
2994	tcache_shutting_down = `1`;
2995	}
2996	text_set_element (__libc_thread_subfreeres, tcache_thread_freeres);
2997
2998	static void
2999	tcache_init(void)
3000	{
3001	mstate ar_ptr;
3002	void *victim = `0`;
3003	const size_t bytes = sizeof (tcache_perthread_struct);
3004
3005	if (tcache_shutting_down)
3006	return;
3007
3008	arena_get (ar_ptr, bytes);
3009	victim = _int_malloc (ar_ptr, bytes);
3010	if (!victim && ar_ptr != NULL)
3011	{
3012	ar_ptr = arena_get_retry (ar_ptr, bytes);
3013	victim = _int_malloc (ar_ptr, bytes);
3014	}
3015
3016
3017	if (ar_ptr != NULL)
3018	__libc_lock_unlock (ar_ptr->mutex);
3019
3020	/ In a low memory situation, we may not be able to allocate memory*
3021	- in which case, we just keep trying later. However, we
3022	typically do this very early, so either there is sufficient
3023	memory, or there isn't enough memory to do non-trivial
3024	allocations anyway. /*
3025	if (victim)
3026	{
3027	tcache = (tcache_perthread_struct *) victim;
3028	memset (tcache, `0`, sizeof (tcache_perthread_struct));
3029	}
3030
3031	}
3032
3033	#define MAYBE_INIT_TCACHE() \
3034	if (__glibc_unlikely (tcache == NULL)) \
3035	tcache_init();
3036
3037	#else
3038	#define MAYBE_INIT_TCACHE()
3039	#endif
3040
3041	void *
3042	__libc_malloc (size_t bytes)
3043	{
3044	mstate ar_ptr;
3045	void *victim;
3046
3047	void (hook) (size_t, const void *)
3048	= atomic_forced_read (__malloc_hook);
3049	if (__builtin_expect (hook != NULL, `0`))
3050	return (*hook)(bytes, RETURN_ADDRESS (`0`));
3051	#if USE_TCACHE
3052	/ int_free also calls request2size, be careful to not pad twice. /
3053	size_t tbytes = request2size (bytes);
3054	size_t tc_idx = csize2tidx (tbytes);
3055
3056	MAYBE_INIT_TCACHE ();
3057
3058	DIAG_PUSH_NEEDS_COMMENT;
3059	if (tc_idx < mp_.tcache_bins
3060	/&& tc_idx < TCACHE_MAX_BINS/ / to appease gcc /
3061	&& tcache
3062	&& tcache->entries[tc_idx] != NULL)
3063	{
3064	return tcache_get (tc_idx);
3065	}
3066	DIAG_POP_NEEDS_COMMENT;
3067	#endif
3068
3069	arena_get (ar_ptr, bytes);
3070
3071	victim = _int_malloc (ar_ptr, bytes);
3072	/ Retry with another arena only if we were able to find a usable arena*
3073	before. /*
3074	if (!victim && ar_ptr != NULL)
3075	{
3076	LIBC_PROBE (memory_malloc_retry, `1`, bytes);
3077	ar_ptr = arena_get_retry (ar_ptr, bytes);
3078	victim = _int_malloc (ar_ptr, bytes);
3079	}
3080
3081	if (ar_ptr != NULL)
3082	__libc_lock_unlock (ar_ptr->mutex);
3083
3084	assert (!victim \|\| chunk_is_mmapped (mem2chunk (victim)) \|\|
3085	ar_ptr == arena_for_chunk (mem2chunk (victim)));
3086	return victim;
3087	}
3088	libc_hidden_def (__libc_malloc)
3089
3090	void
3091	__libc_free (void *mem)
3092	{
3093	mstate ar_ptr;
3094	mchunkptr p; / chunk corresponding to mem /
3095
3096	void (hook) (void* , const* void *)
3097	= atomic_forced_read (__free_hook);
3098	if (__builtin_expect (hook != NULL, `0`))
3099	{
3100	(*hook)(mem, RETURN_ADDRESS (`0`));
3101	return;
3102	}
3103
3104	if (mem == `0`) / free(0) has no effect /
3105	return;
3106
3107	p = mem2chunk (mem);
3108
3109	if (chunk_is_mmapped (p)) / release mmapped memory. /
3110	{
3111	/ See if the dynamic brk/mmap threshold needs adjusting.*
3112	Dumped fake mmapped chunks do not affect the threshold. /*
3113	if (!mp_.no_dyn_threshold
3114	&& chunksize_nomask (p) > mp_.mmap_threshold
3115	&& chunksize_nomask (p) <= DEFAULT_MMAP_THRESHOLD_MAX
3116	&& !DUMPED_MAIN_ARENA_CHUNK (p))
3117	{
3118	mp_.mmap_threshold = chunksize (p);
3119	mp_.trim_threshold = `2` * mp_.mmap_threshold;
3120	LIBC_PROBE (memory_mallopt_free_dyn_thresholds, `2`,
3121	mp_.mmap_threshold, mp_.trim_threshold);
3122	}
3123	munmap_chunk (p);
3124	return;
3125	}
3126
3127	MAYBE_INIT_TCACHE ();
3128
3129	ar_ptr = arena_for_chunk (p);
3130	_int_free (ar_ptr, p, `0`);
3131	}
3132	libc_hidden_def (__libc_free)
3133
3134	void *
3135	__libc_realloc (void *oldmem, size_t bytes)
3136	{
3137	mstate ar_ptr;
3138	INTERNAL_SIZE_T nb; / padded request size /
3139
3140	void newp; /* chunk to return /
3141
3142	void (hook) (void , size_t, const* void *) =
3143	atomic_forced_read (__realloc_hook);
3144	if (__builtin_expect (hook != NULL, `0`))
3145	return (*hook)(oldmem, bytes, RETURN_ADDRESS (`0`));
3146
3147	#if REALLOC_ZERO_BYTES_FREES
3148	if (bytes == `0` && oldmem != NULL)
3149	{
3150	__libc_free (oldmem); return `0`;
3151	}
3152	#endif
3153
3154	/ realloc of null is supposed to be same as malloc /
3155	if (oldmem == `0`)
3156	return __libc_malloc (bytes);
3157
3158	/ chunk corresponding to oldmem /
3159	const mchunkptr oldp = mem2chunk (oldmem);
3160	/ its size /
3161	const INTERNAL_SIZE_T oldsize = chunksize (oldp);
3162
3163	if (chunk_is_mmapped (oldp))
3164	ar_ptr = NULL;
3165	else
3166	{
3167	MAYBE_INIT_TCACHE ();
3168	ar_ptr = arena_for_chunk (oldp);
3169	}
3170
3171	/ Little security check which won't hurt performance: the allocator*
3172	never wrapps around at the end of the address space. Therefore
3173	we can exclude some size values which might appear here by
3174	accident or by "design" from some intruder. We need to bypass
3175	this check for dumped fake mmap chunks from the old main arena
3176	because the new malloc may provide additional alignment. /*
3177	if ((__builtin_expect ((uintptr_t) oldp > (uintptr_t) -oldsize, `0`)
3178	\|\| __builtin_expect (misaligned_chunk (oldp), `0`))
3179	&& !DUMPED_MAIN_ARENA_CHUNK (oldp))
3180	{
3181	malloc_printerr (check_action, "realloc(): invalid pointer", oldmem,
3182	ar_ptr);
3183	return NULL;
3184	}
3185
3186	checked_request2size (bytes, nb);
3187
3188	if (chunk_is_mmapped (oldp))
3189	{
3190	/ If this is a faked mmapped chunk from the dumped main arena,*
3191	always make a copy (and do not free the old chunk). /*
3192	if (DUMPED_MAIN_ARENA_CHUNK (oldp))
3193	{
3194	/ Must alloc, copy, free. /
3195	void *newmem = __libc_malloc (bytes);
3196	if (newmem == `0`)
3197	return NULL;
3198	/ Copy as many bytes as are available from the old chunk*
3199	and fit into the new size. NB: The overhead for faked
3200	mmapped chunks is only SIZE_SZ, not 2 SIZE_SZ as for*
3201	regular mmapped chunks. /*
3202	if (bytes > oldsize - SIZE_SZ)
3203	bytes = oldsize - SIZE_SZ;
3204	memcpy (newmem, oldmem, bytes);
3205	return newmem;
3206	}
3207
3208	void *newmem;
3209
3210	#if HAVE_MREMAP
3211	newp = mremap_chunk (oldp, nb);
3212	if (newp)
3213	return chunk2mem (newp);
3214	#endif
3215	/ Note the extra SIZE_SZ overhead. /
3216	if (oldsize - SIZE_SZ >= nb)
3217	return oldmem; / do nothing /
3218
3219	/ Must alloc, copy, free. /
3220	newmem = __libc_malloc (bytes);
3221	if (newmem == `0`)
3222	return `0`; / propagate failure /
3223
3224	memcpy (newmem, oldmem, oldsize - `2` * SIZE_SZ);
3225	munmap_chunk (oldp);
3226	return newmem;
3227	}
3228
3229	__libc_lock_lock (ar_ptr->mutex);
3230
3231	newp = _int_realloc (ar_ptr, oldp, oldsize, nb);
3232
3233	__libc_lock_unlock (ar_ptr->mutex);
3234	assert (!newp \|\| chunk_is_mmapped (mem2chunk (newp)) \|\|
3235	ar_ptr == arena_for_chunk (mem2chunk (newp)));
3236
3237	if (newp == NULL)
3238	{
3239	/ Try harder to allocate memory in other arenas. /
3240	LIBC_PROBE (memory_realloc_retry, `2`, bytes, oldmem);
3241	newp = __libc_malloc (bytes);
3242	if (newp != NULL)
3243	{
3244	memcpy (newp, oldmem, oldsize - SIZE_SZ);
3245	_int_free (ar_ptr, oldp, `0`);
3246	}
3247	}
3248
3249	return newp;
3250	}
3251	libc_hidden_def (__libc_realloc)
3252
3253	void *
3254	__libc_memalign (size_t alignment, size_t bytes)
3255	{
3256	void *address = RETURN_ADDRESS (`0`);
3257	return _mid_memalign (alignment, bytes, address);
3258	}
3259
3260	static void *
3261	_mid_memalign (size_t alignment, size_t bytes, void *address)
3262	{
3263	mstate ar_ptr;
3264	void *p;
3265
3266	void (hook) (size_t, size_t, const void *) =
3267	atomic_forced_read (__memalign_hook);
3268	if (__builtin_expect (hook != NULL, `0`))
3269	return (*hook)(alignment, bytes, address);
3270
3271	/ If we need less alignment than we give anyway, just relay to malloc. /
3272	if (alignment <= MALLOC_ALIGNMENT)
3273	return __libc_malloc (bytes);
3274
3275	/ Otherwise, ensure that it is at least a minimum chunk size /
3276	if (alignment < MINSIZE)
3277	alignment = MINSIZE;
3278
3279	/ If the alignment is greater than SIZE_MAX / 2 + 1 it cannot be a*
3280	power of 2 and will cause overflow in the check below. /*
3281	if (alignment > SIZE_MAX / `2` + `1`)
3282	{
3283	__set_errno (EINVAL);
3284	return `0`;
3285	}
3286
3287	/ Check for overflow. /
3288	if (bytes > SIZE_MAX - alignment - MINSIZE)
3289	{
3290	__set_errno (ENOMEM);
3291	return `0`;
3292	}
3293
3294
3295	/ Make sure alignment is power of 2. /
3296	if (!powerof2 (alignment))
3297	{
3298	size_t a = MALLOC_ALIGNMENT * `2`;
3299	while (a < alignment)
3300	a <<= `1`;
3301	alignment = a;
3302	}
3303
3304	arena_get (ar_ptr, bytes + alignment + MINSIZE);
3305
3306	p = _int_memalign (ar_ptr, alignment, bytes);
3307	if (!p && ar_ptr != NULL)
3308	{
3309	LIBC_PROBE (memory_memalign_retry, `2`, bytes, alignment);
3310	ar_ptr = arena_get_retry (ar_ptr, bytes);
3311	p = _int_memalign (ar_ptr, alignment, bytes);
3312	}
3313
3314	if (ar_ptr != NULL)
3315	__libc_lock_unlock (ar_ptr->mutex);
3316
3317	assert (!p \|\| chunk_is_mmapped (mem2chunk (p)) \|\|
3318	ar_ptr == arena_for_chunk (mem2chunk (p)));
3319	return p;
3320	}
3321	/ For ISO C11. /
3322	weak_alias (__libc_memalign, aligned_alloc)
3323	libc_hidden_def (__libc_memalign)
3324
3325	void *
3326	__libc_valloc (size_t bytes)
3327	{
3328	if (__malloc_initialized < `0`)
3329	ptmalloc_init ();
3330
3331	void *address = RETURN_ADDRESS (`0`);
3332	size_t pagesize = GLRO (dl_pagesize);
3333	return _mid_memalign (pagesize, bytes, address);
3334	}
3335
3336	void *
3337	__libc_pvalloc (size_t bytes)
3338	{
3339	if (__malloc_initialized < `0`)
3340	ptmalloc_init ();
3341
3342	void *address = RETURN_ADDRESS (`0`);
3343	size_t pagesize = GLRO (dl_pagesize);
3344	size_t rounded_bytes = ALIGN_UP (bytes, pagesize);
3345
3346	/ Check for overflow. /
3347	if (bytes > SIZE_MAX - `2` * pagesize - MINSIZE)
3348	{
3349	__set_errno (ENOMEM);
3350	return `0`;
3351	}
3352
3353	return _mid_memalign (pagesize, rounded_bytes, address);
3354	}
3355
3356	void *
3357	__libc_calloc (size_t n, size_t elem_size)
3358	{
3359	mstate av;
3360	mchunkptr oldtop, p;
3361	INTERNAL_SIZE_T bytes, sz, csz, oldtopsize;
3362	void *mem;
3363	unsigned long clearsize;
3364	unsigned long nclears;
3365	INTERNAL_SIZE_T *d;
3366
3367	/ size_t is unsigned so the behavior on overflow is defined. /
3368	bytes = n * elem_size;
3369	#define HALF_INTERNAL_SIZE_T \
3370	(((INTERNAL_SIZE_T) 1) << (8 * sizeof (INTERNAL_SIZE_T) / 2))
3371	if (__builtin_expect ((n \| elem_size) >= HALF_INTERNAL_SIZE_T, `0`))
3372	{
3373	if (elem_size != `0` && bytes / elem_size != n)
3374	{
3375	__set_errno (ENOMEM);
3376	return `0`;
3377	}
3378	}
3379
3380	void (hook) (size_t, const void *) =
3381	atomic_forced_read (__malloc_hook);
3382	if (__builtin_expect (hook != NULL, `0`))
3383	{
3384	sz = bytes;
3385	mem = (*hook)(sz, RETURN_ADDRESS (`0`));
3386	if (mem == `0`)
3387	return `0`;
3388
3389	return memset (mem, `0`, sz);
3390	}
3391
3392	sz = bytes;
3393
3394	MAYBE_INIT_TCACHE ();
3395
3396	arena_get (av, sz);
3397	if (av)
3398	{
3399	/ Check if we hand out the top chunk, in which case there may be no*
3400	need to clear. /*
3401	#if MORECORE_CLEARS
3402	oldtop = top (av);
3403	oldtopsize = chunksize (top (av));
3404	# if MORECORE_CLEARS < 2
3405	/ Only newly allocated memory is guaranteed to be cleared. /
3406	if (av == &main_arena &&
3407	oldtopsize < mp_.sbrk_base + av->max_system_mem - (char *) oldtop)
3408	oldtopsize = (mp_.sbrk_base + av->max_system_mem - (char *) oldtop);
3409	# endif
3410	if (av != &main_arena)
3411	{
3412	heap_info *heap = heap_for_ptr (oldtop);
3413	if (oldtopsize < (char ) heap + heap->mprotect_size - (char* *) oldtop)
3414	oldtopsize = (char ) heap + heap->mprotect_size - (char* *) oldtop;
3415	}
3416	#endif
3417	}
3418	else
3419	{
3420	/ No usable arenas. /
3421	oldtop = `0`;
3422	oldtopsize = `0`;
3423	}
3424	mem = _int_malloc (av, sz);
3425
3426
3427	assert (!mem \|\| chunk_is_mmapped (mem2chunk (mem)) \|\|
3428	av == arena_for_chunk (mem2chunk (mem)));
3429
3430	if (mem == `0` && av != NULL)
3431	{
3432	LIBC_PROBE (memory_calloc_retry, `1`, sz);
3433	av = arena_get_retry (av, sz);
3434	mem = _int_malloc (av, sz);
3435	}
3436
3437	if (av != NULL)
3438	__libc_lock_unlock (av->mutex);
3439
3440	/ Allocation failed even after a retry. /
3441	if (mem == `0`)
3442	return `0`;
3443
3444	p = mem2chunk (mem);
3445
3446	/ Two optional cases in which clearing not necessary /
3447	if (chunk_is_mmapped (p))
3448	{
3449	if (__builtin_expect (perturb_byte, `0`))
3450	return memset (mem, `0`, sz);
3451
3452	return mem;
3453	}
3454
3455	csz = chunksize (p);
3456
3457	#if MORECORE_CLEARS
3458	if (perturb_byte == `0` && (p == oldtop && csz > oldtopsize))
3459	{
3460	/ clear only the bytes from non-freshly-sbrked memory /
3461	csz = oldtopsize;
3462	}
3463	#endif
3464
3465	/ Unroll clear of <= 36 bytes (72 if 8byte sizes). We know that*
3466	contents have an odd number of INTERNAL_SIZE_T-sized words;
3467	minimally 3. /*
3468	d = (INTERNAL_SIZE_T *) mem;
3469	clearsize = csz - SIZE_SZ;
3470	nclears = clearsize / sizeof (INTERNAL_SIZE_T);
3471	assert (nclears >= `3`);
3472
3473	if (nclears > `9`)
3474	return memset (d, `0`, clearsize);
3475
3476	else
3477	{
3478	*(d + `0`) = `0`;
3479	*(d + `1`) = `0`;
3480	*(d + `2`) = `0`;
3481	if (nclears > `4`)
3482	{
3483	*(d + `3`) = `0`;
3484	*(d + `4`) = `0`;
3485	if (nclears > `6`)
3486	{
3487	*(d + `5`) = `0`;
3488	*(d + `6`) = `0`;
3489	if (nclears > `8`)
3490	{
3491	*(d + `7`) = `0`;
3492	*(d + `8`) = `0`;
3493	}
3494	}
3495	}
3496	}
3497
3498	return mem;
3499	}
3500
3501	/*
3502	------------------------------ malloc ------------------------------
3503	*/
3504
3505	static void *
3506	_int_malloc (mstate av, size_t bytes)
3507	{
3508	INTERNAL_SIZE_T nb; / normalized request size /
3509	unsigned int idx; / associated bin index /
3510	mbinptr bin; / associated bin /
3511
3512	mchunkptr victim; / inspected/selected chunk /
3513	INTERNAL_SIZE_T size; / its size /
3514	int victim_index; / its bin index /
3515
3516	mchunkptr remainder; / remainder from a split /
3517	unsigned long remainder_size; / its size /
3518
3519	unsigned int block; / bit map traverser /
3520	unsigned int bit; / bit map traverser /
3521	unsigned int map; / current word of binmap /
3522
3523	mchunkptr fwd; / misc temp for linking /
3524	mchunkptr bck; / misc temp for linking /
3525
3526	#if USE_TCACHE
3527	size_t tcache_unsorted_count; / count of unsorted chunks processed /
3528	#endif
3529
3530	const char *errstr = NULL;
3531
3532	/*
3533	Convert request size to internal form by adding SIZE_SZ bytes
3534	overhead plus possibly more to obtain necessary alignment and/or
3535	to obtain a size of at least MINSIZE, the smallest allocatable
3536	size. Also, checked_request2size traps (returning 0) request sizes
3537	that are so large that they wrap around zero when padded and
3538	aligned.
3539	*/
3540
3541	checked_request2size (bytes, nb);
3542
3543	/ There are no usable arenas. Fall back to sysmalloc to get a chunk from*
3544	mmap. /*
3545	if (__glibc_unlikely (av == NULL))
3546	{
3547	void *p = sysmalloc (nb, av);
3548	if (p != NULL)
3549	alloc_perturb (p, bytes);
3550	return p;
3551	}
3552
3553	/*
3554	If the size qualifies as a fastbin, first check corresponding bin.
3555	This code is safe to execute even if av is not yet initialized, so we
3556	can try it without checking, which saves some time on this fast path.
3557	*/
3558
3559	#define REMOVE_FB(fb, victim, pp) \
3560	do \
3561	{ \
3562	victim = pp; \
3563	if (victim == NULL) \
3564	break; \
3565	} \
3566	while ((pp = catomic_compare_and_exchange_val_acq (fb, victim->fd, victim)) \
3567	!= victim); \
3568
3569	if ((unsigned long) (nb) <= (unsigned long) (get_max_fast ()))
3570	{
3571	idx = fastbin_index (nb);
3572	mfastbinptr *fb = &fastbin (av, idx);
3573	mchunkptr pp = *fb;
3574	REMOVE_FB (fb, victim, pp);
3575	if (victim != `0`)
3576	{
3577	if (__builtin_expect (fastbin_index (chunksize (victim)) != idx, `0`))
3578	{
3579	errstr = "malloc(): memory corruption (fast)";
3580	errout:
3581	malloc_printerr (check_action, errstr, chunk2mem (victim), av);
3582	return NULL;
3583	}
3584	check_remalloced_chunk (av, victim, nb);
3585	#if USE_TCACHE
3586	/ While we're here, if we see other chunks of the same size,*
3587	stash them in the tcache. /*
3588	size_t tc_idx = csize2tidx (nb);
3589	if (tcache && tc_idx < mp_.tcache_bins)
3590	{
3591	mchunkptr tc_victim;
3592
3593	/ While bin not empty and tcache not full, copy chunks over. /
3594	while (tcache->counts[tc_idx] < mp_.tcache_count
3595	&& (pp = *fb) != NULL)
3596	{
3597	REMOVE_FB (fb, tc_victim, pp);
3598	if (tc_victim != `0`)
3599	{
3600	tcache_put (tc_victim, tc_idx);
3601	}
3602	}
3603	}
3604	#endif
3605	void *p = chunk2mem (victim);
3606	alloc_perturb (p, bytes);
3607	return p;
3608	}
3609	}
3610
3611	/*
3612	If a small request, check regular bin. Since these "smallbins"
3613	hold one size each, no searching within bins is necessary.
3614	(For a large request, we need to wait until unsorted chunks are
3615	processed to find best fit. But for small ones, fits are exact
3616	anyway, so we can check now, which is faster.)
3617	*/
3618
3619	if (in_smallbin_range (nb))
3620	{
3621	idx = smallbin_index (nb);
3622	bin = bin_at (av, idx);
3623
3624	if ((victim = last (bin)) != bin)
3625	{
3626	if (victim == `0`) / initialization check /
3627	malloc_consolidate (av);
3628	else
3629	{
3630	bck = victim->bk;
3631	if (__glibc_unlikely (bck->fd != victim))
3632	{
3633	errstr = "malloc(): smallbin double linked list corrupted";
3634	goto errout;
3635	}
3636	set_inuse_bit_at_offset (victim, nb);
3637	bin->bk = bck;
3638	bck->fd = bin;
3639
3640	if (av != &main_arena)
3641	set_non_main_arena (victim);
3642	check_malloced_chunk (av, victim, nb);
3643	#if USE_TCACHE
3644	/ While we're here, if we see other chunks of the same size,*
3645	stash them in the tcache. /*
3646	size_t tc_idx = csize2tidx (nb);
3647	if (tcache && tc_idx < mp_.tcache_bins)
3648	{
3649	mchunkptr tc_victim;
3650
3651	/ While bin not empty and tcache not full, copy chunks over. /
3652	while (tcache->counts[tc_idx] < mp_.tcache_count
3653	&& (tc_victim = last (bin)) != bin)
3654	{
3655	if (tc_victim != `0`)
3656	{
3657	bck = tc_victim->bk;
3658	set_inuse_bit_at_offset (tc_victim, nb);
3659	if (av != &main_arena)
3660	set_non_main_arena (tc_victim);
3661	bin->bk = bck;
3662	bck->fd = bin;
3663
3664	tcache_put (tc_victim, tc_idx);
3665	}
3666	}
3667	}
3668	#endif
3669	void *p = chunk2mem (victim);
3670	alloc_perturb (p, bytes);
3671	return p;
3672	}
3673	}
3674	}
3675
3676	/*
3677	If this is a large request, consolidate fastbins before continuing.
3678	While it might look excessive to kill all fastbins before
3679	even seeing if there is space available, this avoids
3680	fragmentation problems normally associated with fastbins.
3681	Also, in practice, programs tend to have runs of either small or
3682	large requests, but less often mixtures, so consolidation is not
3683	invoked all that often in most programs. And the programs that
3684	it is called frequently in otherwise tend to fragment.
3685	*/
3686
3687	else
3688	{
3689	idx = largebin_index (nb);
3690	if (have_fastchunks (av))
3691	malloc_consolidate (av);
3692	}
3693
3694	/*
3695	Process recently freed or remaindered chunks, taking one only if
3696	it is exact fit, or, if this a small request, the chunk is remainder from
3697	the most recent non-exact fit. Place other traversed chunks in
3698	bins. Note that this step is the only place in any routine where
3699	chunks are placed in bins.
3700
3701	The outer loop here is needed because we might not realize until
3702	near the end of malloc that we should have consolidated, so must
3703	do so and retry. This happens at most once, and only when we would
3704	otherwise need to expand memory to service a "small" request.
3705	*/
3706
3707	#if USE_TCACHE
3708	INTERNAL_SIZE_T tcache_nb = `0`;
3709	size_t tc_idx = csize2tidx (nb);
3710	if (tcache && tc_idx < mp_.tcache_bins)
3711	tcache_nb = nb;
3712	int return_cached = `0`;
3713
3714	tcache_unsorted_count = `0`;
3715	#endif
3716
3717	for (;; )
3718	{
3719	int iters = `0`;
3720	while ((victim = unsorted_chunks (av)->bk) != unsorted_chunks (av))
3721	{
3722	bck = victim->bk;
3723	if (__builtin_expect (chunksize_nomask (victim) <= `2` * SIZE_SZ, `0`)
3724	\|\| __builtin_expect (chunksize_nomask (victim)
3725	> av->system_mem, `0`))
3726	malloc_printerr (check_action, "malloc(): memory corruption",
3727	chunk2mem (victim), av);
3728	size = chunksize (victim);
3729
3730	/*
3731	If a small request, try to use last remainder if it is the
3732	only chunk in unsorted bin. This helps promote locality for
3733	runs of consecutive small requests. This is the only
3734	exception to best-fit, and applies only when there is
3735	no exact fit for a small chunk.
3736	*/
3737
3738	if (in_smallbin_range (nb) &&
3739	bck == unsorted_chunks (av) &&
3740	victim == av->last_remainder &&
3741	(unsigned long) (size) > (unsigned long) (nb + MINSIZE))
3742	{
3743	/ split and reattach remainder /
3744	remainder_size = size - nb;
3745	remainder = chunk_at_offset (victim, nb);
3746	unsorted_chunks (av)->bk = unsorted_chunks (av)->fd = remainder;
3747	av->last_remainder = remainder;
3748	remainder->bk = remainder->fd = unsorted_chunks (av);
3749	if (!in_smallbin_range (remainder_size))
3750	{
3751	remainder->fd_nextsize = NULL;
3752	remainder->bk_nextsize = NULL;
3753	}
3754
3755	set_head (victim, nb \| PREV_INUSE \|
3756	(av != &main_arena ? NON_MAIN_ARENA : `0`));
3757	set_head (remainder, remainder_size \| PREV_INUSE);
3758	set_foot (remainder, remainder_size);
3759
3760	check_malloced_chunk (av, victim, nb);
3761	void *p = chunk2mem (victim);
3762	alloc_perturb (p, bytes);
3763	return p;
3764	}
3765
3766	/ remove from unsorted list /
3767	unsorted_chunks (av)->bk = bck;
3768	bck->fd = unsorted_chunks (av);
3769
3770	/ Take now instead of binning if exact fit /
3771
3772	if (size == nb)
3773	{
3774	set_inuse_bit_at_offset (victim, size);
3775	if (av != &main_arena)
3776	set_non_main_arena (victim);
3777	#if USE_TCACHE
3778	/ Fill cache first, return to user only if cache fills.*
3779	We may return one of these chunks later. /*
3780	if (tcache_nb
3781	&& tcache->counts[tc_idx] < mp_.tcache_count)
3782	{
3783	tcache_put (victim, tc_idx);
3784	return_cached = `1`;
3785	continue;
3786	}
3787	else
3788	{
3789	#endif
3790	check_malloced_chunk (av, victim, nb);
3791	void *p = chunk2mem (victim);
3792	alloc_perturb (p, bytes);
3793	return p;
3794	#if USE_TCACHE
3795	}
3796	#endif
3797	}
3798
3799	/ place chunk in bin /
3800
3801	if (in_smallbin_range (size))
3802	{
3803	victim_index = smallbin_index (size);
3804	bck = bin_at (av, victim_index);
3805	fwd = bck->fd;
3806	}
3807	else
3808	{
3809	victim_index = largebin_index (size);
3810	bck = bin_at (av, victim_index);
3811	fwd = bck->fd;
3812
3813	/ maintain large bins in sorted order /
3814	if (fwd != bck)
3815	{
3816	/ Or with inuse bit to speed comparisons /
3817	size \|= PREV_INUSE;
3818	/ if smaller than smallest, bypass loop below /
3819	assert (chunk_main_arena (bck->bk));
3820	if ((unsigned long) (size)
3821	< (unsigned long) chunksize_nomask (bck->bk))
3822	{
3823	fwd = bck;
3824	bck = bck->bk;
3825
3826	victim->fd_nextsize = fwd->fd;
3827	victim->bk_nextsize = fwd->fd->bk_nextsize;
3828	fwd->fd->bk_nextsize = victim->bk_nextsize->fd_nextsize = victim;
3829	}
3830	else
3831	{
3832	assert (chunk_main_arena (fwd));
3833	while ((unsigned long) size < chunksize_nomask (fwd))
3834	{
3835	fwd = fwd->fd_nextsize;
3836	assert (chunk_main_arena (fwd));
3837	}
3838
3839	if ((unsigned long) size
3840	== (unsigned long) chunksize_nomask (fwd))
3841	/ Always insert in the second position. /
3842	fwd = fwd->fd;
3843	else
3844	{
3845	victim->fd_nextsize = fwd;
3846	victim->bk_nextsize = fwd->bk_nextsize;
3847	fwd->bk_nextsize = victim;
3848	victim->bk_nextsize->fd_nextsize = victim;
3849	}
3850	bck = fwd->bk;
3851	}
3852	}
3853	else
3854	victim->fd_nextsize = victim->bk_nextsize = victim;
3855	}
3856
3857	mark_bin (av, victim_index);
3858	victim->bk = bck;
3859	victim->fd = fwd;
3860	fwd->bk = victim;
3861	bck->fd = victim;
3862
3863	#if USE_TCACHE
3864	/ If we've processed as many chunks as we're allowed while*
3865	filling the cache, return one of the cached ones. /*
3866	++tcache_unsorted_count;
3867	if (return_cached
3868	&& mp_.tcache_unsorted_limit > `0`
3869	&& tcache_unsorted_count > mp_.tcache_unsorted_limit)
3870	{
3871	return tcache_get (tc_idx);
3872	}
3873	#endif
3874
3875	#define MAX_ITERS 10000
3876	if (++iters >= MAX_ITERS)
3877	break;
3878	}
3879
3880	#if USE_TCACHE
3881	/ If all the small chunks we found ended up cached, return one now. /
3882	if (return_cached)
3883	{
3884	return tcache_get (tc_idx);
3885	}
3886	#endif
3887
3888	/*
3889	If a large request, scan through the chunks of current bin in
3890	sorted order to find smallest that fits. Use the skip list for this.
3891	*/
3892
3893	if (!in_smallbin_range (nb))
3894	{
3895	bin = bin_at (av, idx);
3896
3897	/ skip scan if empty or largest chunk is too small /
3898	if ((victim = first (bin)) != bin
3899	&& (unsigned long) chunksize_nomask (victim)
3900	>= (unsigned long) (nb))
3901	{
3902	victim = victim->bk_nextsize;
3903	while (((unsigned long) (size = chunksize (victim)) <
3904	(unsigned long) (nb)))
3905	victim = victim->bk_nextsize;
3906
3907	/ Avoid removing the first entry for a size so that the skip*
3908	list does not have to be rerouted. /*
3909	if (victim != last (bin)
3910	&& chunksize_nomask (victim)
3911	== chunksize_nomask (victim->fd))
3912	victim = victim->fd;
3913
3914	remainder_size = size - nb;
3915	unlink (av, victim, bck, fwd);
3916
3917	/ Exhaust /
3918	if (remainder_size < MINSIZE)
3919	{
3920	set_inuse_bit_at_offset (victim, size);
3921	if (av != &main_arena)
3922	set_non_main_arena (victim);
3923	}
3924	/ Split /
3925	else
3926	{
3927	remainder = chunk_at_offset (victim, nb);
3928	/ We cannot assume the unsorted list is empty and therefore*
3929	have to perform a complete insert here. /*
3930	bck = unsorted_chunks (av);
3931	fwd = bck->fd;
3932	if (__glibc_unlikely (fwd->bk != bck))
3933	{
3934	errstr = "malloc(): corrupted unsorted chunks";
3935	goto errout;
3936	}
3937	remainder->bk = bck;
3938	remainder->fd = fwd;
3939	bck->fd = remainder;
3940	fwd->bk = remainder;
3941	if (!in_smallbin_range (remainder_size))
3942	{
3943	remainder->fd_nextsize = NULL;
3944	remainder->bk_nextsize = NULL;
3945	}
3946	set_head (victim, nb \| PREV_INUSE \|
3947	(av != &main_arena ? NON_MAIN_ARENA : `0`));
3948	set_head (remainder, remainder_size \| PREV_INUSE);
3949	set_foot (remainder, remainder_size);
3950	}
3951	check_malloced_chunk (av, victim, nb);
3952	void *p = chunk2mem (victim);
3953	alloc_perturb (p, bytes);
3954	return p;
3955	}
3956	}
3957
3958	/*
3959	Search for a chunk by scanning bins, starting with next largest
3960	bin. This search is strictly by best-fit; i.e., the smallest
3961	(with ties going to approximately the least recently used) chunk
3962	that fits is selected.
3963
3964	The bitmap avoids needing to check that most blocks are nonempty.
3965	The particular case of skipping all bins during warm-up phases
3966	when no chunks have been returned yet is faster than it might look.
3967	*/
3968
3969	++idx;
3970	bin = bin_at (av, idx);
3971	block = idx2block (idx);
3972	map = av->binmap[block];
3973	bit = idx2bit (idx);
3974
3975	for (;; )
3976	{
3977	/ Skip rest of block if there are no more set bits in this block. /
3978	if (bit > map \|\| bit == `0`)
3979	{
3980	do
3981	{
3982	if (++block >= BINMAPSIZE) / out of bins /
3983	goto use_top;
3984	}
3985	while ((map = av->binmap[block]) == `0`);
3986
3987	bin = bin_at (av, (block << BINMAPSHIFT));
3988	bit = `1`;
3989	}
3990
3991	/ Advance to bin with set bit. There must be one. /
3992	while ((bit & map) == `0`)
3993	{
3994	bin = next_bin (bin);
3995	bit <<= `1`;
3996	assert (bit != `0`);
3997	}
3998
3999	/ Inspect the bin. It is likely to be non-empty /
4000	victim = last (bin);
4001
4002	/ If a false alarm (empty bin), clear the bit. /
4003	if (victim == bin)
4004	{
4005	av->binmap[block] = map &= ~bit; / Write through /
4006	bin = next_bin (bin);
4007	bit <<= `1`;
4008	}
4009
4010	else
4011	{
4012	size = chunksize (victim);
4013
4014	/ We know the first chunk in this bin is big enough to use. /
4015	assert ((unsigned long) (size) >= (unsigned long) (nb));
4016
4017	remainder_size = size - nb;
4018
4019	/ unlink /
4020	unlink (av, victim, bck, fwd);
4021
4022	/ Exhaust /
4023	if (remainder_size < MINSIZE)
4024	{
4025	set_inuse_bit_at_offset (victim, size);
4026	if (av != &main_arena)
4027	set_non_main_arena (victim);
4028	}
4029
4030	/ Split /
4031	else
4032	{
4033	remainder = chunk_at_offset (victim, nb);
4034
4035	/ We cannot assume the unsorted list is empty and therefore*
4036	have to perform a complete insert here. /*
4037	bck = unsorted_chunks (av);
4038	fwd = bck->fd;
4039	if (__glibc_unlikely (fwd->bk != bck))
4040	{
4041	errstr = "malloc(): corrupted unsorted chunks 2";
4042	goto errout;
4043	}
4044	remainder->bk = bck;
4045	remainder->fd = fwd;
4046	bck->fd = remainder;
4047	fwd->bk = remainder;
4048
4049	/ advertise as last remainder /
4050	if (in_smallbin_range (nb))
4051	av->last_remainder = remainder;
4052	if (!in_smallbin_range (remainder_size))
4053	{
4054	remainder->fd_nextsize = NULL;
4055	remainder->bk_nextsize = NULL;
4056	}
4057	set_head (victim, nb \| PREV_INUSE \|
4058	(av != &main_arena ? NON_MAIN_ARENA : `0`));
4059	set_head (remainder, remainder_size \| PREV_INUSE);
4060	set_foot (remainder, remainder_size);
4061	}
4062	check_malloced_chunk (av, victim, nb);
4063	void *p = chunk2mem (victim);
4064	alloc_perturb (p, bytes);
4065	return p;
4066	}
4067	}
4068
4069	use_top:
4070	/*
4071	If large enough, split off the chunk bordering the end of memory
4072	(held in av->top). Note that this is in accord with the best-fit
4073	search rule. In effect, av->top is treated as larger (and thus
4074	less well fitting) than any other available chunk since it can
4075	be extended to be as large as necessary (up to system
4076	limitations).
4077
4078	We require that av->top always exists (i.e., has size >=
4079	MINSIZE) after initialization, so if it would otherwise be
4080	exhausted by current request, it is replenished. (The main
4081	reason for ensuring it exists is that we may need MINSIZE space
4082	to put in fenceposts in sysmalloc.)
4083	*/
4084
4085	victim = av->top;
4086	size = chunksize (victim);
4087
4088	if ((unsigned long) (size) >= (unsigned long) (nb + MINSIZE))
4089	{
4090	remainder_size = size - nb;
4091	remainder = chunk_at_offset (victim, nb);
4092	av->top = remainder;
4093	set_head (victim, nb \| PREV_INUSE \|
4094	(av != &main_arena ? NON_MAIN_ARENA : `0`));
4095	set_head (remainder, remainder_size \| PREV_INUSE);
4096
4097	check_malloced_chunk (av, victim, nb);
4098	void *p = chunk2mem (victim);
4099	alloc_perturb (p, bytes);
4100	return p;
4101	}
4102
4103	/ When we are using atomic ops to free fast chunks we can get*
4104	here for all block sizes. /*
4105	else if (have_fastchunks (av))
4106	{
4107	malloc_consolidate (av);
4108	/ restore original bin index /
4109	if (in_smallbin_range (nb))
4110	idx = smallbin_index (nb);
4111	else
4112	idx = largebin_index (nb);
4113	}
4114
4115	/*
4116	Otherwise, relay to handle system-dependent cases
4117	*/
4118	else
4119	{
4120	void *p = sysmalloc (nb, av);
4121	if (p != NULL)
4122	alloc_perturb (p, bytes);
4123	return p;
4124	}
4125	}
4126	}
4127
4128	/*
4129	------------------------------ free ------------------------------
4130	*/
4131
4132	static void
4133	_int_free (mstate av, mchunkptr p, int have_lock)
4134	{
4135	INTERNAL_SIZE_T size; / its size /
4136	mfastbinptr fb; /* associated fastbin /
4137	mchunkptr nextchunk; / next contiguous chunk /
4138	INTERNAL_SIZE_T nextsize; / its size /
4139	int nextinuse; / true if nextchunk is used /
4140	INTERNAL_SIZE_T prevsize; / size of previous contiguous chunk /
4141	mchunkptr bck; / misc temp for linking /
4142	mchunkptr fwd; / misc temp for linking /
4143
4144	const char *errstr = NULL;
4145	int locked = `0`;
4146
4147	size = chunksize (p);
4148
4149	/ Little security check which won't hurt performance: the*
4150	allocator never wrapps around at the end of the address space.
4151	Therefore we can exclude some size values which might appear
4152	here by accident or by "design" from some intruder. /*
4153	if (__builtin_expect ((uintptr_t) p > (uintptr_t) -size, `0`)
4154	\|\| __builtin_expect (misaligned_chunk (p), `0`))
4155	{
4156	errstr = "free(): invalid pointer";
4157	errout:
4158	if (!have_lock && locked)
4159	__libc_lock_unlock (av->mutex);
4160	malloc_printerr (check_action, errstr, chunk2mem (p), av);
4161	return;
4162	}
4163	/ We know that each chunk is at least MINSIZE bytes in size or a*
4164	multiple of MALLOC_ALIGNMENT. /*
4165	if (__glibc_unlikely (size < MINSIZE \|\| !aligned_OK (size)))
4166	{
4167	errstr = "free(): invalid size";
4168	goto errout;
4169	}
4170
4171	check_inuse_chunk(av, p);
4172
4173	#if USE_TCACHE
4174	{
4175	size_t tc_idx = csize2tidx (size);
4176
4177	if (tcache
4178	&& tc_idx < mp_.tcache_bins
4179	&& tcache->counts[tc_idx] < mp_.tcache_count)
4180	{
4181	tcache_put (p, tc_idx);
4182	return;
4183	}
4184	}
4185	#endif
4186
4187	/*
4188	If eligible, place chunk on a fastbin so it can be found
4189	and used quickly in malloc.
4190	*/
4191
4192	if ((unsigned long)(size) <= (unsigned long)(get_max_fast ())
4193
4194	#if TRIM_FASTBINS
4195	/*
4196	If TRIM_FASTBINS set, don't place chunks
4197	bordering top into fastbins
4198	*/
4199	&& (chunk_at_offset(p, size) != av->top)
4200	#endif
4201	) {
4202
4203	if (__builtin_expect (chunksize_nomask (chunk_at_offset (p, size))
4204	<= `2` * SIZE_SZ, `0`)
4205	\|\| __builtin_expect (chunksize (chunk_at_offset (p, size))
4206	>= av->system_mem, `0`))
4207	{
4208	/ We might not have a lock at this point and concurrent modifications*
4209	of system_mem might have let to a false positive. Redo the test
4210	after getting the lock. /*
4211	if (have_lock
4212	\|\| ({ assert (locked == `0`);
4213	__libc_lock_lock (av->mutex);
4214	locked = `1`;
4215	chunksize_nomask (chunk_at_offset (p, size)) <= `2` * SIZE_SZ
4216	\|\| chunksize (chunk_at_offset (p, size)) >= av->system_mem;
4217	}))
4218	{
4219	errstr = "free(): invalid next size (fast)";
4220	goto errout;
4221	}
4222	if (! have_lock)
4223	{
4224	__libc_lock_unlock (av->mutex);
4225	locked = `0`;
4226	}
4227	}
4228
4229	free_perturb (chunk2mem(p), size - `2` * SIZE_SZ);
4230
4231	set_fastchunks(av);
4232	unsigned int idx = fastbin_index(size);
4233	fb = &fastbin (av, idx);
4234
4235	/ Atomically link P to its fastbin: P->FD = FB; FB = P; /
4236	mchunkptr old = *fb, old2;
4237	unsigned int old_idx = ~`0u`;
4238	do
4239	{
4240	/ Check that the top of the bin is not the record we are going to add*
4241	(i.e., double free). /*
4242	if (__builtin_expect (old == p, `0`))
4243	{
4244	errstr = "double free or corruption (fasttop)";
4245	goto errout;
4246	}
4247	/ Check that size of fastbin chunk at the top is the same as*
4248	size of the chunk that we are adding. We can dereference OLD
4249	only if we have the lock, otherwise it might have already been
4250	deallocated. See use of OLD_IDX below for the actual check. /*
4251	if (have_lock && old != NULL)
4252	old_idx = fastbin_index(chunksize(old));
4253	p->fd = old2 = old;
4254	}
4255	while ((old = catomic_compare_and_exchange_val_rel (fb, p, old2)) != old2);
4256
4257	if (have_lock && old != NULL && __builtin_expect (old_idx != idx, `0`))
4258	{
4259	errstr = "invalid fastbin entry (free)";
4260	goto errout;
4261	}
4262	}
4263
4264	/*
4265	Consolidate other non-mmapped chunks as they arrive.
4266	*/
4267
4268	else if (!chunk_is_mmapped(p)) {
4269	if (! have_lock) {
4270	__libc_lock_lock (av->mutex);
4271	locked = `1`;
4272	}
4273
4274	nextchunk = chunk_at_offset(p, size);
4275
4276	/ Lightweight tests: check whether the block is already the*
4277	top block. /*
4278	if (__glibc_unlikely (p == av->top))
4279	{
4280	errstr = "double free or corruption (top)";
4281	goto errout;
4282	}
4283	/ Or whether the next chunk is beyond the boundaries of the arena. /
4284	if (__builtin_expect (contiguous (av)
4285	&& (char *) nextchunk
4286	>= ((char *) av->top + chunksize(av->top)), `0`))
4287	{
4288	errstr = "double free or corruption (out)";
4289	goto errout;
4290	}
4291	/ Or whether the block is actually not marked used. /
4292	if (__glibc_unlikely (!prev_inuse(nextchunk)))
4293	{
4294	errstr = "double free or corruption (!prev)";
4295	goto errout;
4296	}
4297
4298	nextsize = chunksize(nextchunk);
4299	if (__builtin_expect (chunksize_nomask (nextchunk) <= `2` * SIZE_SZ, `0`)
4300	\|\| __builtin_expect (nextsize >= av->system_mem, `0`))
4301	{
4302	errstr = "free(): invalid next size (normal)";
4303	goto errout;
4304	}
4305
4306	free_perturb (chunk2mem(p), size - `2` * SIZE_SZ);
4307
4308	/ consolidate backward /
4309	if (!prev_inuse(p)) {
4310	prevsize = prev_size (p);
4311	size += prevsize;
4312	p = chunk_at_offset(p, -((long) prevsize));
4313	unlink(av, p, bck, fwd);
4314	}
4315
4316	if (nextchunk != av->top) {
4317	/ get and clear inuse bit /
4318	nextinuse = inuse_bit_at_offset(nextchunk, nextsize);
4319
4320	/ consolidate forward /
4321	if (!nextinuse) {
4322	unlink(av, nextchunk, bck, fwd);
4323	size += nextsize;
4324	} else
4325	clear_inuse_bit_at_offset(nextchunk, `0`);
4326
4327	/*
4328	Place the chunk in unsorted chunk list. Chunks are
4329	not placed into regular bins until after they have
4330	been given one chance to be used in malloc.
4331	*/
4332
4333	bck = unsorted_chunks(av);
4334	fwd = bck->fd;
4335	if (__glibc_unlikely (fwd->bk != bck))
4336	{
4337	errstr = "free(): corrupted unsorted chunks";
4338	goto errout;
4339	}
4340	p->fd = fwd;
4341	p->bk = bck;
4342	if (!in_smallbin_range(size))
4343	{
4344	p->fd_nextsize = NULL;
4345	p->bk_nextsize = NULL;
4346	}
4347	bck->fd = p;
4348	fwd->bk = p;
4349
4350	set_head(p, size \| PREV_INUSE);
4351	set_foot(p, size);
4352
4353	check_free_chunk(av, p);
4354	}
4355
4356	/*
4357	If the chunk borders the current high end of memory,
4358	consolidate into top
4359	*/
4360
4361	else {
4362	size += nextsize;
4363	set_head(p, size \| PREV_INUSE);
4364	av->top = p;
4365	check_chunk(av, p);
4366	}
4367
4368	/*
4369	If freeing a large space, consolidate possibly-surrounding
4370	chunks. Then, if the total unused topmost memory exceeds trim
4371	threshold, ask malloc_trim to reduce top.
4372
4373	Unless max_fast is 0, we don't know if there are fastbins
4374	bordering top, so we cannot tell for sure whether threshold
4375	has been reached unless fastbins are consolidated. But we
4376	don't want to consolidate on each free. As a compromise,
4377	consolidation is performed if FASTBIN_CONSOLIDATION_THRESHOLD
4378	is reached.
4379	*/
4380
4381	if ((unsigned long)(size) >= FASTBIN_CONSOLIDATION_THRESHOLD) {
4382	if (have_fastchunks(av))
4383	malloc_consolidate(av);
4384
4385	if (av == &main_arena) {
4386	#ifndef MORECORE_CANNOT_TRIM
4387	if ((unsigned long)(chunksize(av->top)) >=
4388	(unsigned long)(mp_.trim_threshold))
4389	systrim(mp_.top_pad, av);
4390	#endif
4391	} else {
4392	/ Always try heap_trim(), even if the top chunk is not*
4393	large, because the corresponding heap might go away. /*
4394	heap_info *heap = heap_for_ptr(top(av));
4395
4396	assert(heap->ar_ptr == av);
4397	heap_trim(heap, mp_.top_pad);
4398	}
4399	}
4400
4401	if (! have_lock) {
4402	assert (locked);
4403	__libc_lock_unlock (av->mutex);
4404	}
4405	}
4406	/*
4407	If the chunk was allocated via mmap, release via munmap().
4408	*/
4409
4410	else {
4411	munmap_chunk (p);
4412	}
4413	}
4414
4415	/*
4416	------------------------- malloc_consolidate -------------------------
4417
4418	malloc_consolidate is a specialized version of free() that tears
4419	down chunks held in fastbins. Free itself cannot be used for this
4420	purpose since, among other things, it might place chunks back onto
4421	fastbins. So, instead, we need to use a minor variant of the same
4422	code.
4423
4424	Also, because this routine needs to be called the first time through
4425	malloc anyway, it turns out to be the perfect place to trigger
4426	initialization code.
4427	*/
4428
4429	static void malloc_consolidate(mstate av)
4430	{
4431	mfastbinptr* fb; / current fastbin being consolidated /
4432	mfastbinptr* maxfb; / last fastbin (for loop control) /
4433	mchunkptr p; / current chunk being consolidated /
4434	mchunkptr nextp; / next chunk to consolidate /
4435	mchunkptr unsorted_bin; / bin header /
4436	mchunkptr first_unsorted; / chunk to link to /
4437
4438	/ These have same use as in free() /
4439	mchunkptr nextchunk;
4440	INTERNAL_SIZE_T size;
4441	INTERNAL_SIZE_T nextsize;
4442	INTERNAL_SIZE_T prevsize;
4443	int nextinuse;
4444	mchunkptr bck;
4445	mchunkptr fwd;
4446
4447	/*
4448	If max_fast is 0, we know that av hasn't
4449	yet been initialized, in which case do so below
4450	*/
4451
4452	if (get_max_fast () != `0`) {
4453	clear_fastchunks(av);
4454
4455	unsorted_bin = unsorted_chunks(av);
4456
4457	/*
4458	Remove each chunk from fast bin and consolidate it, placing it
4459	then in unsorted bin. Among other reasons for doing this,
4460	placing in unsorted bin avoids needing to calculate actual bins
4461	until malloc is sure that chunks aren't immediately going to be
4462	reused anyway.
4463	*/
4464
4465	maxfb = &fastbin (av, NFASTBINS - `1`);
4466	fb = &fastbin (av, `0`);
4467	do {
4468	p = atomic_exchange_acq (fb, NULL);
4469	if (p != `0`) {
4470	do {
4471	check_inuse_chunk(av, p);
4472	nextp = p->fd;
4473
4474	/ Slightly streamlined version of consolidation code in free() /
4475	size = chunksize (p);
4476	nextchunk = chunk_at_offset(p, size);
4477	nextsize = chunksize(nextchunk);
4478
4479	if (!prev_inuse(p)) {
4480	prevsize = prev_size (p);
4481	size += prevsize;
4482	p = chunk_at_offset(p, -((long) prevsize));
4483	unlink(av, p, bck, fwd);
4484	}
4485
4486	if (nextchunk != av->top) {
4487	nextinuse = inuse_bit_at_offset(nextchunk, nextsize);
4488
4489	if (!nextinuse) {
4490	size += nextsize;
4491	unlink(av, nextchunk, bck, fwd);
4492	} else
4493	clear_inuse_bit_at_offset(nextchunk, `0`);
4494
4495	first_unsorted = unsorted_bin->fd;
4496	unsorted_bin->fd = p;
4497	first_unsorted->bk = p;
4498
4499	if (!in_smallbin_range (size)) {
4500	p->fd_nextsize = NULL;
4501	p->bk_nextsize = NULL;
4502	}
4503
4504	set_head(p, size \| PREV_INUSE);
4505	p->bk = unsorted_bin;
4506	p->fd = first_unsorted;
4507	set_foot(p, size);
4508	}
4509
4510	else {
4511	size += nextsize;
4512	set_head(p, size \| PREV_INUSE);
4513	av->top = p;
4514	}
4515
4516	} while ( (p = nextp) != `0`);
4517
4518	}
4519	} while (fb++ != maxfb);
4520	}
4521	else {
4522	malloc_init_state(av);
4523	check_malloc_state(av);
4524	}
4525	}
4526
4527	/*
4528	------------------------------ realloc ------------------------------
4529	*/
4530
4531	void*
4532	_int_realloc(mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
4533	INTERNAL_SIZE_T nb)
4534	{
4535	mchunkptr newp; / chunk to return /
4536	INTERNAL_SIZE_T newsize; / its size /
4537	void* newmem; / corresponding user mem /
4538
4539	mchunkptr next; / next contiguous chunk after oldp /
4540
4541	mchunkptr remainder; / extra space at end of newp /
4542	unsigned long remainder_size; / its size /
4543
4544	mchunkptr bck; / misc temp for linking /
4545	mchunkptr fwd; / misc temp for linking /
4546
4547	unsigned long copysize; / bytes to copy /
4548	unsigned int ncopies; / INTERNAL_SIZE_T words to copy /
4549	INTERNAL_SIZE_T* s; / copy source /
4550	INTERNAL_SIZE_T* d; / copy destination /
4551
4552	const char *errstr = NULL;
4553
4554	/ oldmem size /
4555	if (__builtin_expect (chunksize_nomask (oldp) <= `2` * SIZE_SZ, `0`)
4556	\|\| __builtin_expect (oldsize >= av->system_mem, `0`))
4557	{
4558	errstr = "realloc(): invalid old size";
4559	errout:
4560	malloc_printerr (check_action, errstr, chunk2mem (oldp), av);
4561	return NULL;
4562	}
4563
4564	check_inuse_chunk (av, oldp);
4565
4566	/ All callers already filter out mmap'ed chunks. /
4567	assert (!chunk_is_mmapped (oldp));
4568
4569	next = chunk_at_offset (oldp, oldsize);
4570	INTERNAL_SIZE_T nextsize = chunksize (next);
4571	if (__builtin_expect (chunksize_nomask (next) <= `2` * SIZE_SZ, `0`)
4572	\|\| __builtin_expect (nextsize >= av->system_mem, `0`))
4573	{
4574	errstr = "realloc(): invalid next size";
4575	goto errout;
4576	}
4577
4578	if ((unsigned long) (oldsize) >= (unsigned long) (nb))
4579	{
4580	/ already big enough; split below /
4581	newp = oldp;
4582	newsize = oldsize;
4583	}
4584
4585	else
4586	{
4587	/ Try to expand forward into top /
4588	if (next == av->top &&
4589	(unsigned long) (newsize = oldsize + nextsize) >=
4590	(unsigned long) (nb + MINSIZE))
4591	{
4592	set_head_size (oldp, nb \| (av != &main_arena ? NON_MAIN_ARENA : `0`));
4593	av->top = chunk_at_offset (oldp, nb);
4594	set_head (av->top, (newsize - nb) \| PREV_INUSE);
4595	check_inuse_chunk (av, oldp);
4596	return chunk2mem (oldp);
4597	}
4598
4599	/ Try to expand forward into next chunk; split off remainder below /
4600	else if (next != av->top &&
4601	!inuse (next) &&
4602	(unsigned long) (newsize = oldsize + nextsize) >=
4603	(unsigned long) (nb))
4604	{
4605	newp = oldp;
4606	unlink (av, next, bck, fwd);
4607	}
4608
4609	/ allocate, copy, free /
4610	else
4611	{
4612	newmem = _int_malloc (av, nb - MALLOC_ALIGN_MASK);
4613	if (newmem == `0`)
4614	return `0`; / propagate failure /
4615
4616	newp = mem2chunk (newmem);
4617	newsize = chunksize (newp);
4618
4619	/*
4620	Avoid copy if newp is next chunk after oldp.
4621	*/
4622	if (newp == next)
4623	{
4624	newsize += oldsize;
4625	newp = oldp;
4626	}
4627	else
4628	{
4629	/*
4630	Unroll copy of <= 36 bytes (72 if 8byte sizes)
4631	We know that contents have an odd number of
4632	INTERNAL_SIZE_T-sized words; minimally 3.
4633	*/
4634
4635	copysize = oldsize - SIZE_SZ;
4636	s = (INTERNAL_SIZE_T *) (chunk2mem (oldp));
4637	d = (INTERNAL_SIZE_T *) (newmem);
4638	ncopies = copysize / sizeof (INTERNAL_SIZE_T);
4639	assert (ncopies >= `3`);
4640
4641	if (ncopies > `9`)
4642	memcpy (d, s, copysize);
4643
4644	else
4645	{
4646	(d + `0`) = (s + `0`);
4647	(d + `1`) = (s + `1`);
4648	(d + `2`) = (s + `2`);
4649	if (ncopies > `4`)
4650	{
4651	(d + `3`) = (s + `3`);
4652	(d + `4`) = (s + `4`);
4653	if (ncopies > `6`)
4654	{
4655	(d + `5`) = (s + `5`);
4656	(d + `6`) = (s + `6`);
4657	if (ncopies > `8`)
4658	{
4659	(d + `7`) = (s + `7`);
4660	(d + `8`) = (s + `8`);
4661	}
4662	}
4663	}
4664	}
4665
4666	_int_free (av, oldp, `1`);
4667	check_inuse_chunk (av, newp);
4668	return chunk2mem (newp);
4669	}
4670	}
4671	}
4672
4673	/ If possible, free extra space in old or extended chunk /
4674
4675	assert ((unsigned long) (newsize) >= (unsigned long) (nb));
4676
4677	remainder_size = newsize - nb;
4678
4679	if (remainder_size < MINSIZE) / not enough extra to split off /
4680	{
4681	set_head_size (newp, newsize \| (av != &main_arena ? NON_MAIN_ARENA : `0`));
4682	set_inuse_bit_at_offset (newp, newsize);
4683	}
4684	else / split remainder /
4685	{
4686	remainder = chunk_at_offset (newp, nb);
4687	set_head_size (newp, nb \| (av != &main_arena ? NON_MAIN_ARENA : `0`));
4688	set_head (remainder, remainder_size \| PREV_INUSE \|
4689	(av != &main_arena ? NON_MAIN_ARENA : `0`));
4690	/ Mark remainder as inuse so free() won't complain /
4691	set_inuse_bit_at_offset (remainder, remainder_size);
4692	_int_free (av, remainder, `1`);
4693	}
4694
4695	check_inuse_chunk (av, newp);
4696	return chunk2mem (newp);
4697	}
4698
4699	/*
4700	------------------------------ memalign ------------------------------
4701	*/
4702
4703	static void *
4704	_int_memalign (mstate av, size_t alignment, size_t bytes)
4705	{
4706	INTERNAL_SIZE_T nb; / padded request size /
4707	char m; /* memory returned by malloc call /
4708	mchunkptr p; / corresponding chunk /
4709	char brk; /* alignment point within p /
4710	mchunkptr newp; / chunk to return /
4711	INTERNAL_SIZE_T newsize; / its size /
4712	INTERNAL_SIZE_T leadsize; / leading space before alignment point /
4713	mchunkptr remainder; / spare room at end to split off /
4714	unsigned long remainder_size; / its size /
4715	INTERNAL_SIZE_T size;
4716
4717
4718
4719	checked_request2size (bytes, nb);
4720
4721	/*
4722	Strategy: find a spot within that chunk that meets the alignment
4723	request, and then possibly free the leading and trailing space.
4724	*/
4725
4726
4727	/ Call malloc with worst case padding to hit alignment. /
4728
4729	m = (char *) (_int_malloc (av, nb + alignment + MINSIZE));
4730
4731	if (m == `0`)
4732	return `0`; / propagate failure /
4733
4734	p = mem2chunk (m);
4735
4736	if ((((unsigned long) (m)) % alignment) != `0`) / misaligned /
4737
4738	{ /*
4739	Find an aligned spot inside chunk. Since we need to give back
4740	leading space in a chunk of at least MINSIZE, if the first
4741	calculation places us at a spot with less than MINSIZE leader,
4742	we can move to the next aligned spot -- we've allocated enough
4743	total room so that this is always possible.
4744	*/
4745	brk = (char ) mem2chunk (((unsigned* long) (m + alignment - `1`)) &
4746	- ((signed long) alignment));
4747	if ((unsigned long) (brk - (char *) (p)) < MINSIZE)
4748	brk += alignment;
4749
4750	newp = (mchunkptr) brk;
4751	leadsize = brk - (char *) (p);
4752	newsize = chunksize (p) - leadsize;
4753
4754	/ For mmapped chunks, just adjust offset /
4755	if (chunk_is_mmapped (p))
4756	{
4757	set_prev_size (newp, prev_size (p) + leadsize);
4758	set_head (newp, newsize \| IS_MMAPPED);
4759	return chunk2mem (newp);
4760	}
4761
4762	/ Otherwise, give back leader, use the rest /
4763	set_head (newp, newsize \| PREV_INUSE \|
4764	(av != &main_arena ? NON_MAIN_ARENA : `0`));
4765	set_inuse_bit_at_offset (newp, newsize);
4766	set_head_size (p, leadsize \| (av != &main_arena ? NON_MAIN_ARENA : `0`));
4767	_int_free (av, p, `1`);
4768	p = newp;
4769
4770	assert (newsize >= nb &&
4771	(((unsigned long) (chunk2mem (p))) % alignment) == `0`);
4772	}
4773
4774	/ Also give back spare room at the end /
4775	if (!chunk_is_mmapped (p))
4776	{
4777	size = chunksize (p);
4778	if ((unsigned long) (size) > (unsigned long) (nb + MINSIZE))
4779	{
4780	remainder_size = size - nb;
4781	remainder = chunk_at_offset (p, nb);
4782	set_head (remainder, remainder_size \| PREV_INUSE \|
4783	(av != &main_arena ? NON_MAIN_ARENA : `0`));
4784	set_head_size (p, nb);
4785	_int_free (av, remainder, `1`);
4786	}
4787	}
4788
4789	check_inuse_chunk (av, p);
4790	return chunk2mem (p);
4791	}
4792
4793
4794	/*
4795	------------------------------ malloc_trim ------------------------------
4796	*/
4797
4798	static int
4799	mtrim (mstate av, size_t pad)
4800	{
4801	/ Don't touch corrupt arenas. /
4802	if (arena_is_corrupt (av))
4803	return `0`;
4804
4805	/ Ensure initialization/consolidation /
4806	malloc_consolidate (av);
4807
4808	const size_t ps = GLRO (dl_pagesize);
4809	int psindex = bin_index (ps);
4810	const size_t psm1 = ps - `1`;
4811
4812	int result = `0`;
4813	for (int i = `1`; i < NBINS; ++i)
4814	if (i == `1` \|\| i >= psindex)
4815	{
4816	mbinptr bin = bin_at (av, i);
4817
4818	for (mchunkptr p = last (bin); p != bin; p = p->bk)
4819	{
4820	INTERNAL_SIZE_T size = chunksize (p);
4821
4822	if (size > psm1 + sizeof (struct malloc_chunk))
4823	{
4824	/ See whether the chunk contains at least one unused page. /
4825	char paligned_mem = (char* *) (((uintptr_t) p
4826	+ sizeof (struct malloc_chunk)
4827	+ psm1) & ~psm1);
4828
4829	assert ((char ) chunk2mem (p) + `4` SIZE_SZ <= paligned_mem);
4830	assert ((char *) p + size > paligned_mem);
4831
4832	/ This is the size we could potentially free. /
4833	size -= paligned_mem - (char *) p;
4834
4835	if (size > psm1)
4836	{
4837	#if MALLOC_DEBUG
4838	/ When debugging we simulate destroying the memory*
4839	content. /*
4840	memset (paligned_mem, `0x89`, size & ~psm1);
4841	#endif
4842	__madvise (paligned_mem, size & ~psm1, MADV_DONTNEED);
4843
4844	result = `1`;
4845	}
4846	}
4847	}
4848	}
4849
4850	#ifndef MORECORE_CANNOT_TRIM
4851	return result \| (av == &main_arena ? systrim (pad, av) : `0`);
4852
4853	#else
4854	return result;
4855	#endif
4856	}
4857
4858
4859	int
4860	__malloc_trim (size_t s)
4861	{
4862	int result = `0`;
4863
4864	if (__malloc_initialized < `0`)
4865	ptmalloc_init ();
4866
4867	mstate ar_ptr = &main_arena;
4868	do
4869	{
4870	__libc_lock_lock (ar_ptr->mutex);
4871	result \|= mtrim (ar_ptr, s);
4872	__libc_lock_unlock (ar_ptr->mutex);
4873
4874	ar_ptr = ar_ptr->next;
4875	}
4876	while (ar_ptr != &main_arena);
4877
4878	return result;
4879	}
4880
4881
4882	/*
4883	------------------------- malloc_usable_size -------------------------
4884	*/
4885
4886	static size_t
4887	musable (void *mem)
4888	{
4889	mchunkptr p;
4890	if (mem != `0`)
4891	{
4892	p = mem2chunk (mem);
4893
4894	if (__builtin_expect (using_malloc_checking == `1`, `0`))
4895	return malloc_check_get_size (p);
4896
4897	if (chunk_is_mmapped (p))
4898	{
4899	if (DUMPED_MAIN_ARENA_CHUNK (p))
4900	return chunksize (p) - SIZE_SZ;
4901	else
4902	return chunksize (p) - `2` * SIZE_SZ;
4903	}
4904	else if (inuse (p))
4905	return chunksize (p) - SIZE_SZ;
4906	}
4907	return `0`;
4908	}
4909
4910
4911	size_t
4912	__malloc_usable_size (void *m)
4913	{
4914	size_t result;
4915
4916	result = musable (m);
4917	return result;
4918	}
4919
4920	/*
4921	------------------------------ mallinfo ------------------------------
4922	Accumulate malloc statistics for arena AV into M.
4923	*/
4924
4925	static void
4926	int_mallinfo (mstate av, struct mallinfo *m)
4927	{
4928	size_t i;
4929	mbinptr b;
4930	mchunkptr p;
4931	INTERNAL_SIZE_T avail;
4932	INTERNAL_SIZE_T fastavail;
4933	int nblocks;
4934	int nfastblocks;
4935
4936	/ Ensure initialization /
4937	if (av->top == `0`)
4938	malloc_consolidate (av);
4939
4940	check_malloc_state (av);
4941
4942	/ Account for top /
4943	avail = chunksize (av->top);
4944	nblocks = `1`; / top always exists /
4945
4946	/ traverse fastbins /
4947	nfastblocks = `0`;
4948	fastavail = `0`;
4949
4950	for (i = `0`; i < NFASTBINS; ++i)
4951	{
4952	for (p = fastbin (av, i); p != `0`; p = p->fd)
4953	{
4954	++nfastblocks;
4955	fastavail += chunksize (p);
4956	}
4957	}
4958
4959	avail += fastavail;
4960
4961	/ traverse regular bins /
4962	for (i = `1`; i < NBINS; ++i)
4963	{
4964	b = bin_at (av, i);
4965	for (p = last (b); p != b; p = p->bk)
4966	{
4967	++nblocks;
4968	avail += chunksize (p);
4969	}
4970	}
4971
4972	m->smblks += nfastblocks;
4973	m->ordblks += nblocks;
4974	m->fordblks += avail;
4975	m->uordblks += av->system_mem - avail;
4976	m->arena += av->system_mem;
4977	m->fsmblks += fastavail;
4978	if (av == &main_arena)
4979	{
4980	m->hblks = mp_.n_mmaps;
4981	m->hblkhd = mp_.mmapped_mem;
4982	m->usmblks = `0`;
4983	m->keepcost = chunksize (av->top);
4984	}
4985	}
4986
4987
4988	struct mallinfo
4989	__libc_mallinfo (void)
4990	{
4991	struct mallinfo m;
4992	mstate ar_ptr;
4993
4994	if (__malloc_initialized < `0`)
4995	ptmalloc_init ();
4996
4997	memset (&m, `0`, sizeof (m));
4998	ar_ptr = &main_arena;
4999	do
5000	{
5001	__libc_lock_lock (ar_ptr->mutex);
5002	int_mallinfo (ar_ptr, &m);
5003	__libc_lock_unlock (ar_ptr->mutex);
5004
5005	ar_ptr = ar_ptr->next;
5006	}
5007	while (ar_ptr != &main_arena);
5008
5009	return m;
5010	}
5011
5012	/*
5013	------------------------------ malloc_stats ------------------------------
5014	*/
5015
5016	void
5017	__malloc_stats (void)
5018	{
5019	int i;
5020	mstate ar_ptr;
5021	unsigned int in_use_b = mp_.mmapped_mem, system_b = in_use_b;
5022
5023	if (__malloc_initialized < `0`)
5024	ptmalloc_init ();
5025	_IO_flockfile (stderr);
5026	int old_flags2 = ((_IO_FILE *) stderr)->_flags2;
5027	((_IO_FILE *) stderr)->_flags2 \|= _IO_FLAGS2_NOTCANCEL;
5028	for (i = `0`, ar_ptr = &main_arena;; i++)
5029	{
5030	struct mallinfo mi;
5031
5032	memset (&mi, `0`, sizeof (mi));
5033	__libc_lock_lock (ar_ptr->mutex);
5034	int_mallinfo (ar_ptr, &mi);
5035	fprintf (stderr, "Arena %d:\n", i);
5036	fprintf (stderr, "system bytes = %10u\n", (unsigned int) mi.arena);
5037	fprintf (stderr, "in use bytes = %10u\n", (unsigned int) mi.uordblks);
5038	#if MALLOC_DEBUG > 1
5039	if (i > `0`)
5040	dump_heap (heap_for_ptr (top (ar_ptr)));
5041	#endif
5042	system_b += mi.arena;
5043	in_use_b += mi.uordblks;
5044	__libc_lock_unlock (ar_ptr->mutex);
5045	ar_ptr = ar_ptr->next;
5046	if (ar_ptr == &main_arena)
5047	break;
5048	}
5049	fprintf (stderr, "Total (incl. mmap):\n");
5050	fprintf (stderr, "system bytes = %10u\n", system_b);
5051	fprintf (stderr, "in use bytes = %10u\n", in_use_b);
5052	fprintf (stderr, "max mmap regions = %10u\n", (unsigned int) mp_.max_n_mmaps);
5053	fprintf (stderr, "max mmap bytes = %10lu\n",
5054	(unsigned long) mp_.max_mmapped_mem);
5055	((_IO_FILE *) stderr)->_flags2 \|= old_flags2;
5056	_IO_funlockfile (stderr);
5057	}
5058
5059
5060	/*
5061	------------------------------ mallopt ------------------------------
5062	*/
5063	static inline int
5064	__always_inline
5065	do_set_trim_threshold (size_t value)
5066	{
5067	LIBC_PROBE (memory_mallopt_trim_threshold, `3`, value, mp_.trim_threshold,
5068	mp_.no_dyn_threshold);
5069	mp_.trim_threshold = value;
5070	mp_.no_dyn_threshold = `1`;
5071	return `1`;
5072	}
5073
5074	static inline int
5075	__always_inline
5076	do_set_top_pad (size_t value)
5077	{
5078	LIBC_PROBE (memory_mallopt_top_pad, `3`, value, mp_.top_pad,
5079	mp_.no_dyn_threshold);
5080	mp_.top_pad = value;
5081	mp_.no_dyn_threshold = `1`;
5082	return `1`;
5083	}
5084
5085	static inline int
5086	__always_inline
5087	do_set_mmap_threshold (size_t value)
5088	{
5089	/ Forbid setting the threshold too high. /
5090	if (value <= HEAP_MAX_SIZE / `2`)
5091	{
5092	LIBC_PROBE (memory_mallopt_mmap_threshold, `3`, value, mp_.mmap_threshold,
5093	mp_.no_dyn_threshold);
5094	mp_.mmap_threshold = value;
5095	mp_.no_dyn_threshold = `1`;
5096	return `1`;
5097	}
5098	return `0`;
5099	}
5100
5101	static inline int
5102	__always_inline
5103	do_set_mmaps_max (int32_t value)
5104	{
5105	LIBC_PROBE (memory_mallopt_mmap_max, `3`, value, mp_.n_mmaps_max,
5106	mp_.no_dyn_threshold);
5107	mp_.n_mmaps_max = value;
5108	mp_.no_dyn_threshold = `1`;
5109	return `1`;
5110	}
5111
5112	static inline int
5113	__always_inline
5114	do_set_mallopt_check (int32_t value)
5115	{
5116	LIBC_PROBE (memory_mallopt_check_action, `2`, value, check_action);
5117	check_action = value;
5118	return `1`;
5119	}
5120
5121	static inline int
5122	__always_inline
5123	do_set_perturb_byte (int32_t value)
5124	{
5125	LIBC_PROBE (memory_mallopt_perturb, `2`, value, perturb_byte);
5126	perturb_byte = value;
5127	return `1`;
5128	}
5129
5130	static inline int
5131	__always_inline
5132	do_set_arena_test (size_t value)
5133	{
5134	LIBC_PROBE (memory_mallopt_arena_test, `2`, value, mp_.arena_test);
5135	mp_.arena_test = value;
5136	return `1`;
5137	}
5138
5139	static inline int
5140	__always_inline
5141	do_set_arena_max (size_t value)
5142	{
5143	LIBC_PROBE (memory_mallopt_arena_max, `2`, value, mp_.arena_max);
5144	mp_.arena_max = value;
5145	return `1`;
5146	}
5147
5148	#if USE_TCACHE
5149	static inline int
5150	__always_inline
5151	do_set_tcache_max (size_t value)
5152	{
5153	if (value >= `0` && value <= MAX_TCACHE_SIZE)
5154	{
5155	LIBC_PROBE (memory_tunable_tcache_max_bytes, `2`, value, mp_.tcache_max_bytes);
5156	mp_.tcache_max_bytes = value;
5157	mp_.tcache_bins = csize2tidx (request2size(value)) + `1`;
5158	}
5159	return `1`;
5160	}
5161
5162	static inline int
5163	__always_inline
5164	do_set_tcache_count (size_t value)
5165	{
5166	LIBC_PROBE (memory_tunable_tcache_count, `2`, value, mp_.tcache_count);
5167	mp_.tcache_count = value;
5168	return `1`;
5169	}
5170
5171	static inline int
5172	__always_inline
5173	do_set_tcache_unsorted_limit (size_t value)
5174	{
5175	LIBC_PROBE (memory_tunable_tcache_unsorted_limit, `2`, value, mp_.tcache_unsorted_limit);
5176	mp_.tcache_unsorted_limit = value;
5177	return `1`;
5178	}
5179	#endif
5180
5181	int
5182	__libc_mallopt (int param_number, int value)
5183	{
5184	mstate av = &main_arena;
5185	int res = `1`;
5186
5187	if (__malloc_initialized < `0`)
5188	ptmalloc_init ();
5189	__libc_lock_lock (av->mutex);
5190	/ Ensure initialization/consolidation /
5191	malloc_consolidate (av);
5192
5193	LIBC_PROBE (memory_mallopt, `2`, param_number, value);
5194
5195	switch (param_number)
5196	{
5197	case M_MXFAST:
5198	if (value >= `0` && value <= MAX_FAST_SIZE)
5199	{
5200	LIBC_PROBE (memory_mallopt_mxfast, `2`, value, get_max_fast ());
5201	set_max_fast (value);
5202	}
5203	else
5204	res = `0`;
5205	break;
5206
5207	case M_TRIM_THRESHOLD:
5208	do_set_trim_threshold (value);
5209	break;
5210
5211	case M_TOP_PAD:
5212	do_set_top_pad (value);
5213	break;
5214
5215	case M_MMAP_THRESHOLD:
5216	res = do_set_mmap_threshold (value);
5217	break;
5218
5219	case M_MMAP_MAX:
5220	do_set_mmaps_max (value);
5221	break;
5222
5223	case M_CHECK_ACTION:
5224	do_set_mallopt_check (value);
5225	break;
5226
5227	case M_PERTURB:
5228	do_set_perturb_byte (value);
5229	break;
5230
5231	case M_ARENA_TEST:
5232	if (value > `0`)
5233	do_set_arena_test (value);
5234	break;
5235
5236	case M_ARENA_MAX:
5237	if (value > `0`)
5238	do_set_arena_max (value);
5239	break;
5240	}
5241	__libc_lock_unlock (av->mutex);
5242	return res;
5243	}
5244	libc_hidden_def (__libc_mallopt)
5245
5246
5247	/*
5248	-------------------- Alternative MORECORE functions --------------------
5249	*/
5250
5251
5252	/*
5253	General Requirements for MORECORE.
5254
5255	The MORECORE function must have the following properties:
5256
5257	If MORECORE_CONTIGUOUS is false:
5258
5259	* MORECORE must allocate in multiples of pagesize. It will
5260	only be called with arguments that are multiples of pagesize.
5261
5262	* MORECORE(0) must return an address that is at least
5263	MALLOC_ALIGNMENT aligned. (Page-aligning always suffices.)
5264
5265	else (i.e. If MORECORE_CONTIGUOUS is true):
5266
5267	* Consecutive calls to MORECORE with positive arguments
5268	return increasing addresses, indicating that space has been
5269	contiguously extended.
5270
5271	* MORECORE need not allocate in multiples of pagesize.
5272	Calls to MORECORE need not have args of multiples of pagesize.
5273
5274	* MORECORE need not page-align.
5275
5276	In either case:
5277
5278	* MORECORE may allocate more memory than requested. (Or even less,
5279	but this will generally result in a malloc failure.)
5280
5281	* MORECORE must not allocate memory when given argument zero, but
5282	instead return one past the end address of memory from previous
5283	nonzero call. This malloc does NOT call MORECORE(0)
5284	until at least one call with positive arguments is made, so
5285	the initial value returned is not important.
5286
5287	* Even though consecutive calls to MORECORE need not return contiguous
5288	addresses, it must be OK for malloc'ed chunks to span multiple
5289	regions in those cases where they do happen to be contiguous.
5290
5291	* MORECORE need not handle negative arguments -- it may instead
5292	just return MORECORE_FAILURE when given negative arguments.
5293	Negative arguments are always multiples of pagesize. MORECORE
5294	must not misinterpret negative args as large positive unsigned
5295	args. You can suppress all such calls from even occurring by defining
5296	MORECORE_CANNOT_TRIM,
5297
5298	There is some variation across systems about the type of the
5299	argument to sbrk/MORECORE. If size_t is unsigned, then it cannot
5300	actually be size_t, because sbrk supports negative args, so it is
5301	normally the signed type of the same width as size_t (sometimes
5302	declared as "intptr_t", and sometimes "ptrdiff_t"). It doesn't much
5303	matter though. Internally, we use "long" as arguments, which should
5304	work across all reasonable possibilities.
5305
5306	Additionally, if MORECORE ever returns failure for a positive
5307	request, then mmap is used as a noncontiguous system allocator. This
5308	is a useful backup strategy for systems with holes in address spaces
5309	-- in this case sbrk cannot contiguously expand the heap, but mmap
5310	may be able to map noncontiguous space.
5311
5312	If you'd like mmap to ALWAYS be used, you can define MORECORE to be
5313	a function that always returns MORECORE_FAILURE.
5314
5315	If you are using this malloc with something other than sbrk (or its
5316	emulation) to supply memory regions, you probably want to set
5317	MORECORE_CONTIGUOUS as false. As an example, here is a custom
5318	allocator kindly contributed for pre-OSX macOS. It uses virtually
5319	but not necessarily physically contiguous non-paged memory (locked
5320	in, present and won't get swapped out). You can use it by
5321	uncommenting this section, adding some #includes, and setting up the
5322	appropriate defines above:
5323
5324	*#define MORECORE osMoreCore
5325	*#define MORECORE_CONTIGUOUS 0
5326
5327	There is also a shutdown routine that should somehow be called for
5328	cleanup upon program exit.
5329
5330	*#define MAX_POOL_ENTRIES 100
5331	#define MINIMUM_MORECORE_SIZE (64 1024)
5332	static int next_os_pool;
5333	void our_os_pools[MAX_POOL_ENTRIES];*
5334
5335	void osMoreCore(int size)*
5336	{
5337	void ptr = 0;*
5338	static void sbrk_top = 0;*
5339
5340	if (size > 0)
5341	{
5342	if (size < MINIMUM_MORECORE_SIZE)
5343	size = MINIMUM_MORECORE_SIZE;
5344	if (CurrentExecutionLevel() == kTaskLevel)
5345	ptr = PoolAllocateResident(size + RM_PAGE_SIZE, 0);
5346	if (ptr == 0)
5347	{
5348	return (void ) MORECORE_FAILURE;*
5349	}
5350	// save ptrs so they can be freed during cleanup
5351	our_os_pools[next_os_pool] = ptr;
5352	next_os_pool++;
5353	ptr = (void ) ((((unsigned long) ptr) + RM_PAGE_MASK) & ~RM_PAGE_MASK);*
5354	sbrk_top = (char ) ptr + size;*
5355	return ptr;
5356	}
5357	else if (size < 0)
5358	{
5359	// we don't currently support shrink behavior
5360	return (void ) MORECORE_FAILURE;*
5361	}
5362	else
5363	{
5364	return sbrk_top;
5365	}
5366	}
5367
5368	// cleanup any allocated memory pools
5369	// called as last thing before shutting down driver
5370
5371	void osCleanupMem(void)
5372	{
5373	void ptr;
5374
5375	for (ptr = our_os_pools; ptr < &our_os_pools[MAX_POOL_ENTRIES]; ptr++)
5376	if (ptr)*
5377	{
5378	PoolDeallocate(ptr);*
5379	* ptr = 0;
5380	}
5381	}
5382
5383	*/
5384
5385
5386	/ Helper code. /
5387
5388	extern char **__libc_argv attribute_hidden;
5389
5390	static void
5391	malloc_printerr (int action, const char str, void* *ptr, mstate ar_ptr)
5392	{
5393	/ Avoid using this arena in future. We do not attempt to synchronize this*
5394	with anything else because we minimally want to ensure that __libc_message
5395	gets its resources safely without stumbling on the current corruption. /*
5396	if (ar_ptr)
5397	set_arena_corrupt (ar_ptr);
5398
5399	if ((action & `5`) == `5`)
5400	__libc_message ((action & `2`) ? (do_abort \| do_backtrace) : do_message,
5401	"%s\n", str);
5402	else if (action & `1`)
5403	{
5404	char buf[`2` * sizeof (uintptr_t) + `1`];
5405
5406	buf[sizeof (buf) - `1`] = `'\0'`;
5407	char cp = _itoa_word ((uintptr_t) ptr, &buf[sizeof* (buf) - `1`], `16`, `0`);
5408	while (cp > buf)
5409	*--cp = `'0'`;
5410
5411	__libc_message ((action & `2`) ? (do_abort \| do_backtrace) : do_message,
5412	"* Error in `%s': %s: 0x%s *\n",
5413	__libc_argv[`0`] ? : "<unknown>", str, cp);
5414	}
5415	else if (action & `2`)
5416	abort ();
5417	}
5418
5419	/ We need a wrapper function for one of the additions of POSIX. /
5420	int
5421	__posix_memalign (void **memptr, size_t alignment, size_t size)
5422	{
5423	void *mem;
5424
5425	/ Test whether the SIZE argument is valid. It must be a power of*
5426	two multiple of sizeof (void ). /
5427	if (alignment % sizeof (void *) != `0`
5428	\|\| !powerof2 (alignment / sizeof (void *))
5429	\|\| alignment == `0`)
5430	return EINVAL;
5431
5432
5433	void *address = RETURN_ADDRESS (`0`);
5434	mem = _mid_memalign (alignment, size, address);
5435
5436	if (mem != NULL)
5437	{
5438	*memptr = mem;
5439	return `0`;
5440	}
5441
5442	return ENOMEM;
5443	}
5444	weak_alias (__posix_memalign, posix_memalign)
5445
5446
5447	int
5448	__malloc_info (int options, FILE *fp)
5449	{
5450	/ For now, at least. /
5451	if (options != `0`)
5452	return EINVAL;
5453
5454	int n = `0`;
5455	size_t total_nblocks = `0`;
5456	size_t total_nfastblocks = `0`;
5457	size_t total_avail = `0`;
5458	size_t total_fastavail = `0`;
5459	size_t total_system = `0`;
5460	size_t total_max_system = `0`;
5461	size_t total_aspace = `0`;
5462	size_t total_aspace_mprotect = `0`;
5463
5464
5465
5466	if (__malloc_initialized < `0`)
5467	ptmalloc_init ();
5468
5469	fputs ("<malloc version=\"1\">\n", fp);
5470
5471	/ Iterate over all arenas currently in use. /
5472	mstate ar_ptr = &main_arena;
5473	do
5474	{
5475	fprintf (fp, "<heap nr=\"%d\">\n<sizes>\n", n++);
5476
5477	size_t nblocks = `0`;
5478	size_t nfastblocks = `0`;
5479	size_t avail = `0`;
5480	size_t fastavail = `0`;
5481	struct
5482	{
5483	size_t from;
5484	size_t to;
5485	size_t total;
5486	size_t count;
5487	} sizes[NFASTBINS + NBINS - `1`];
5488	#define nsizes (sizeof (sizes) / sizeof (sizes[0]))
5489
5490	__libc_lock_lock (ar_ptr->mutex);
5491
5492	for (size_t i = `0`; i < NFASTBINS; ++i)
5493	{
5494	mchunkptr p = fastbin (ar_ptr, i);
5495	if (p != NULL)
5496	{
5497	size_t nthissize = `0`;
5498	size_t thissize = chunksize (p);
5499
5500	while (p != NULL)
5501	{
5502	++nthissize;
5503	p = p->fd;
5504	}
5505
5506	fastavail += nthissize * thissize;
5507	nfastblocks += nthissize;
5508	sizes[i].from = thissize - (MALLOC_ALIGNMENT - `1`);
5509	sizes[i].to = thissize;
5510	sizes[i].count = nthissize;
5511	}
5512	else
5513	sizes[i].from = sizes[i].to = sizes[i].count = `0`;
5514
5515	sizes[i].total = sizes[i].count * sizes[i].to;
5516	}
5517
5518
5519	mbinptr bin;
5520	struct malloc_chunk *r;
5521
5522	for (size_t i = `1`; i < NBINS; ++i)
5523	{
5524	bin = bin_at (ar_ptr, i);
5525	r = bin->fd;
5526	sizes[NFASTBINS - `1` + i].from = ~((size_t) `0`);
5527	sizes[NFASTBINS - `1` + i].to = sizes[NFASTBINS - `1` + i].total
5528	= sizes[NFASTBINS - `1` + i].count = `0`;
5529
5530	if (r != NULL)
5531	while (r != bin)
5532	{
5533	size_t r_size = chunksize_nomask (r);
5534	++sizes[NFASTBINS - `1` + i].count;
5535	sizes[NFASTBINS - `1` + i].total += r_size;
5536	sizes[NFASTBINS - `1` + i].from
5537	= MIN (sizes[NFASTBINS - `1` + i].from, r_size);
5538	sizes[NFASTBINS - `1` + i].to = MAX (sizes[NFASTBINS - `1` + i].to,
5539	r_size);
5540
5541	r = r->fd;
5542	}
5543
5544	if (sizes[NFASTBINS - `1` + i].count == `0`)
5545	sizes[NFASTBINS - `1` + i].from = `0`;
5546	nblocks += sizes[NFASTBINS - `1` + i].count;
5547	avail += sizes[NFASTBINS - `1` + i].total;
5548	}
5549
5550	__libc_lock_unlock (ar_ptr->mutex);
5551
5552	total_nfastblocks += nfastblocks;
5553	total_fastavail += fastavail;
5554
5555	total_nblocks += nblocks;
5556	total_avail += avail;
5557
5558	for (size_t i = `0`; i < nsizes; ++i)
5559	if (sizes[i].count != `0` && i != NFASTBINS)
5560	fprintf (fp, " \
5561	<size from=\"%zu\" to=\"%zu\" total=\"%zu\" count=\"%zu\"/>\n",
5562	sizes[i].from, sizes[i].to, sizes[i].total, sizes[i].count);
5563
5564	if (sizes[NFASTBINS].count != `0`)
5565	fprintf (fp, "\
5566	<unsorted from=\"%zu\" to=\"%zu\" total=\"%zu\" count=\"%zu\"/>\n",
5567	sizes[NFASTBINS].from, sizes[NFASTBINS].to,
5568	sizes[NFASTBINS].total, sizes[NFASTBINS].count);
5569
5570	total_system += ar_ptr->system_mem;
5571	total_max_system += ar_ptr->max_system_mem;
5572
5573	fprintf (fp,
5574	"</sizes>\n<total type=\"fast\" count=\"%zu\" size=\"%zu\"/>\n"
5575	"<total type=\"rest\" count=\"%zu\" size=\"%zu\"/>\n"
5576	"<system type=\"current\" size=\"%zu\"/>\n"
5577	"<system type=\"max\" size=\"%zu\"/>\n",
5578	nfastblocks, fastavail, nblocks, avail,
5579	ar_ptr->system_mem, ar_ptr->max_system_mem);
5580
5581	if (ar_ptr != &main_arena)
5582	{
5583	heap_info *heap = heap_for_ptr (top (ar_ptr));
5584	fprintf (fp,
5585	"<aspace type=\"total\" size=\"%zu\"/>\n"
5586	"<aspace type=\"mprotect\" size=\"%zu\"/>\n",
5587	heap->size, heap->mprotect_size);
5588	total_aspace += heap->size;
5589	total_aspace_mprotect += heap->mprotect_size;
5590	}
5591	else
5592	{
5593	fprintf (fp,
5594	"<aspace type=\"total\" size=\"%zu\"/>\n"
5595	"<aspace type=\"mprotect\" size=\"%zu\"/>\n",
5596	ar_ptr->system_mem, ar_ptr->system_mem);
5597	total_aspace += ar_ptr->system_mem;
5598	total_aspace_mprotect += ar_ptr->system_mem;
5599	}
5600
5601	fputs ("</heap>\n", fp);
5602	ar_ptr = ar_ptr->next;
5603	}
5604	while (ar_ptr != &main_arena);
5605
5606	fprintf (fp,
5607	"<total type=\"fast\" count=\"%zu\" size=\"%zu\"/>\n"
5608	"<total type=\"rest\" count=\"%zu\" size=\"%zu\"/>\n"
5609	"<total type=\"mmap\" count=\"%d\" size=\"%zu\"/>\n"
5610	"<system type=\"current\" size=\"%zu\"/>\n"
5611	"<system type=\"max\" size=\"%zu\"/>\n"
5612	"<aspace type=\"total\" size=\"%zu\"/>\n"
5613	"<aspace type=\"mprotect\" size=\"%zu\"/>\n"
5614	"</malloc>\n",
5615	total_nfastblocks, total_fastavail, total_nblocks, total_avail,
5616	mp_.n_mmaps, mp_.mmapped_mem,
5617	total_system, total_max_system,
5618	total_aspace, total_aspace_mprotect);
5619
5620	return `0`;
5621	}
5622	weak_alias (__malloc_info, malloc_info)
5623
5624
5625	strong_alias (__libc_calloc, __calloc) weak_alias (__libc_calloc, calloc)
5626	strong_alias (__libc_free, __free) strong_alias (__libc_free, free)
5627	strong_alias (__libc_malloc, __malloc) strong_alias (__libc_malloc, malloc)
5628	strong_alias (__libc_memalign, __memalign)
5629	weak_alias (__libc_memalign, memalign)
5630	strong_alias (__libc_realloc, __realloc) strong_alias (__libc_realloc, realloc)
5631	strong_alias (__libc_valloc, __valloc) weak_alias (__libc_valloc, valloc)
5632	strong_alias (__libc_pvalloc, __pvalloc) weak_alias (__libc_pvalloc, pvalloc)
5633	strong_alias (__libc_mallinfo, __mallinfo)
5634	weak_alias (__libc_mallinfo, mallinfo)
5635	strong_alias (__libc_mallopt, __mallopt) weak_alias (__libc_mallopt, mallopt)
5636
5637	weak_alias (__malloc_stats, malloc_stats)
5638	weak_alias (__malloc_usable_size, malloc_usable_size)
5639	weak_alias (__malloc_trim, malloc_trim)
5640
5641	#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_26)
5642	compat_symbol (libc, __libc_free, cfree, GLIBC_2_0);
5643	#endif
5644
5645	/ ------------------------------------------------------------*
5646	History:
5647
5648	[see ftp://g.oswego.edu/pub/misc/malloc.c for the history of dlmalloc]
5649
5650	*/
5651	/*
5652	* Local variables:
5653	* c-basic-offset: 2
5654	* End:
5655	*/
5656

Browse the source code of glibc/malloc/malloc.c