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

1	/ Malloc implementation for multiple threads without lock contention.*
2	Copyright (C) 1996-2024 Free Software Foundation, Inc.
3	Copyright The GNU Toolchain Authors.
4	This file is part of the GNU C Library.
5
6	The GNU C Library is free software; you can redistribute it and/or
7	modify it under the terms of the GNU Lesser General Public License as
8	published by the Free Software Foundation; either version 2.1 of the
9	License, or (at your option) any later version.
10
11	The GNU C Library is distributed in the hope that it will be useful,
12	but WITHOUT ANY WARRANTY; without even the implied warranty of
13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14	Lesser General Public License for more details.
15
16	You should have received a copy of the GNU Lesser General Public
17	License along with the GNU C Library; see the file COPYING.LIB. If
18	not, see <https://www.gnu.org/licenses/>. /*
19
20	/*
21	This is a version (aka ptmalloc2) of malloc/free/realloc written by
22	Doug Lea and adapted to multiple threads/arenas by Wolfram Gloger.
23
24	There have been substantial changes made after the integration into
25	glibc in all parts of the code. Do not look for much commonality
26	with the ptmalloc2 version.
27
28	* Version ptmalloc2-20011215
29	based on:
30	VERSION 2.7.0 Sun Mar 11 14:14:06 2001 Doug Lea (dl at gee)
31
32	* Quickstart
33
34	In order to compile this implementation, a Makefile is provided with
35	the ptmalloc2 distribution, which has pre-defined targets for some
36	popular systems (e.g. "make posix" for Posix threads). All that is
37	typically required with regard to compiler flags is the selection of
38	the thread package via defining one out of USE_PTHREADS, USE_THR or
39	USE_SPROC. Check the thread-m.h file for what effects this has.
40	Many/most systems will additionally require USE_TSD_DATA_HACK to be
41	defined, so this is the default for "make posix".
42
43	* Why use this malloc?
44
45	This is not the fastest, most space-conserving, most portable, or
46	most tunable malloc ever written. However it is among the fastest
47	while also being among the most space-conserving, portable and tunable.
48	Consistent balance across these factors results in a good general-purpose
49	allocator for malloc-intensive programs.
50
51	The main properties of the algorithms are:
52	* For large (>= 512 bytes) requests, it is a pure best-fit allocator,
53	with ties normally decided via FIFO (i.e. least recently used).
54	* For small (<= 64 bytes by default) requests, it is a caching
55	allocator, that maintains pools of quickly recycled chunks.
56	* In between, and for combinations of large and small requests, it does
57	the best it can trying to meet both goals at once.
58	* For very large requests (>= 128KB by default), it relies on system
59	memory mapping facilities, if supported.
60
61	For a longer but slightly out of date high-level description, see
62	http://gee.cs.oswego.edu/dl/html/malloc.html
63
64	You may already by default be using a C library containing a malloc
65	that is based on some version of this malloc (for example in
66	linux). You might still want to use the one in this file in order to
67	customize settings or to avoid overheads associated with library
68	versions.
69
70	* Contents, described in more detail in "description of public routines" below.
71
72	Standard (ANSI/SVID/...) functions:
73	malloc(size_t n);
74	calloc(size_t n_elements, size_t element_size);
75	free(void p);*
76	realloc(void p, size_t n);*
77	memalign(size_t alignment, size_t n);
78	valloc(size_t n);
79	mallinfo()
80	mallopt(int parameter_number, int parameter_value)
81
82	Additional functions:
83	independent_calloc(size_t n_elements, size_t size, void chunks[]);*
84	independent_comalloc(size_t n_elements, size_t sizes[], void chunks[]);*
85	pvalloc(size_t n);
86	malloc_trim(size_t pad);
87	malloc_usable_size(void p);*
88	malloc_stats();
89
90	* Vital statistics:
91
92	Supported pointer representation: 4 or 8 bytes
93	Supported size_t representation: 4 or 8 bytes
94	Note that size_t is allowed to be 4 bytes even if pointers are 8.
95	You can adjust this by defining INTERNAL_SIZE_T
96
97	Alignment: 2 sizeof(size_t) (default)*
98	(i.e., 8 byte alignment with 4byte size_t). This suffices for
99	nearly all current machines and C compilers. However, you can
100	define MALLOC_ALIGNMENT to be wider than this if necessary.
101
102	Minimum overhead per allocated chunk: 4 or 8 bytes
103	Each malloced chunk has a hidden word of overhead holding size
104	and status information.
105
106	Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
107	8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
108
109	When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
110	ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
111	needed; 4 (8) for a trailing size field and 8 (16) bytes for
112	free list pointers. Thus, the minimum allocatable size is
113	16/24/32 bytes.
114
115	Even a request for zero bytes (i.e., malloc(0)) returns a
116	pointer to something of the minimum allocatable size.
117
118	The maximum overhead wastage (i.e., number of extra bytes
119	allocated than were requested in malloc) is less than or equal
120	to the minimum size, except for requests >= mmap_threshold that
121	are serviced via mmap(), where the worst case wastage is 2 *
122	sizeof(size_t) bytes plus the remainder from a system page (the
123	minimal mmap unit); typically 4096 or 8192 bytes.
124
125	Maximum allocated size: 4-byte size_t: 2^32 minus about two pages
126	8-byte size_t: 2^64 minus about two pages
127
128	It is assumed that (possibly signed) size_t values suffice to
129	represent chunk sizes. `Possibly signed' is due to the fact
130	that `size_t' may be defined on a system as either a signed or
131	an unsigned type. The ISO C standard says that it must be
132	unsigned, but a few systems are known not to adhere to this.
133	Additionally, even when size_t is unsigned, sbrk (which is by
134	default used to obtain memory from system) accepts signed
135	arguments, and may not be able to handle size_t-wide arguments
136	with negative sign bit. Generally, values that would
137	appear as negative after accounting for overhead and alignment
138	are supported only via mmap(), which does not have this
139	limitation.
140
141	Requests for sizes outside the allowed range will perform an optional
142	failure action and then return null. (Requests may also
143	also fail because a system is out of memory.)
144
145	Thread-safety: thread-safe
146
147	Compliance: I believe it is compliant with the 1997 Single Unix Specification
148	Also SVID/XPG, ANSI C, and probably others as well.
149
150	* Synopsis of compile-time options:
151
152	People have reported using previous versions of this malloc on all
153	versions of Unix, sometimes by tweaking some of the defines
154	below. It has been tested most extensively on Solaris and Linux.
155	People also report using it in stand-alone embedded systems.
156
157	The implementation is in straight, hand-tuned ANSI C. It is not
158	at all modular. (Sorry!) It uses a lot of macros. To be at all
159	usable, this code should be compiled using an optimizing compiler
160	(for example gcc -O3) that can simplify expressions and control
161	paths. (FAQ: some macros import variables as arguments rather than
162	declare locals because people reported that some debuggers
163	otherwise get confused.)
164
165	OPTION DEFAULT VALUE
166
167	Compilation Environment options:
168
169	HAVE_MREMAP 0
170
171	Changing default word sizes:
172
173	INTERNAL_SIZE_T size_t
174
175	Configuration and functionality options:
176
177	USE_PUBLIC_MALLOC_WRAPPERS NOT defined
178	USE_MALLOC_LOCK NOT defined
179	MALLOC_DEBUG NOT defined
180	REALLOC_ZERO_BYTES_FREES 1
181	TRIM_FASTBINS 0
182
183	Options for customizing MORECORE:
184
185	MORECORE sbrk
186	MORECORE_FAILURE -1
187	MORECORE_CONTIGUOUS 1
188	MORECORE_CANNOT_TRIM NOT defined
189	MORECORE_CLEARS 1
190	MMAP_AS_MORECORE_SIZE (1024 1024)*
191
192	Tuning options that are also dynamically changeable via mallopt:
193
194	DEFAULT_MXFAST 64 (for 32bit), 128 (for 64bit)
195	DEFAULT_TRIM_THRESHOLD 128 1024*
196	DEFAULT_TOP_PAD 0
197	DEFAULT_MMAP_THRESHOLD 128 1024*
198	DEFAULT_MMAP_MAX 65536
199
200	There are several other #defined constants and macros that you
201	probably don't want to touch unless you are extending or adapting malloc. /*
202
203	/*
204	void is the pointer type that malloc should say it returns*
205	*/
206
207	#ifndef void
208	#define void void
209	#endif /void/
210
211	#include <stddef.h> /* for size_t */
212	#include <stdlib.h> /* for getenv(), abort() */
213	#include <unistd.h> /* for __libc_enable_secure */
214
215	#include <atomic.h>
216	#include <_itoa.h>
217	#include <bits/wordsize.h>
218	#include <sys/sysinfo.h>
219
220	#include <ldsodefs.h>
221	#include <setvmaname.h>
222
223	#include <unistd.h>
224	#include <stdio.h> /* needed for malloc_stats */
225	#include <errno.h>
226	#include <assert.h>
227
228	#include <shlib-compat.h>
229
230	/ For uintptr_t. /
231	#include <stdint.h>
232
233	/ For va_arg, va_start, va_end. /
234	#include <stdarg.h>
235
236	/ For MIN, MAX, powerof2. /
237	#include <sys/param.h>
238
239	/ For ALIGN_UP et. al. /
240	#include <libc-pointer-arith.h>
241
242	/ For DIAG_PUSH/POP_NEEDS_COMMENT et al. /
243	#include <libc-diag.h>
244
245	/ For memory tagging. /
246	#include <libc-mtag.h>
247
248	#include <malloc/malloc-internal.h>
249
250	/ For SINGLE_THREAD_P. /
251	#include <sysdep-cancel.h>
252
253	#include <libc-internal.h>
254
255	/ For tcache double-free check. /
256	#include <random-bits.h>
257	#include <sys/random.h>
258	#include <not-cancel.h>
259
260	/*
261	Debugging:
262
263	Because freed chunks may be overwritten with bookkeeping fields, this
264	malloc will often die when freed memory is overwritten by user
265	programs. This can be very effective (albeit in an annoying way)
266	in helping track down dangling pointers.
267
268	If you compile with -DMALLOC_DEBUG, a number of assertion checks are
269	enabled that will catch more memory errors. You probably won't be
270	able to make much sense of the actual assertion errors, but they
271	should help you locate incorrectly overwritten memory. The checking
272	is fairly extensive, and will slow down execution
273	noticeably. Calling malloc_stats or mallinfo with MALLOC_DEBUG set
274	will attempt to check every non-mmapped allocated and free chunk in
275	the course of computing the summaries. (By nature, mmapped regions
276	cannot be checked very much automatically.)
277
278	Setting MALLOC_DEBUG may also be helpful if you are trying to modify
279	this code. The assertions in the check routines spell out in more
280	detail the assumptions and invariants underlying the algorithms.
281
282	Setting MALLOC_DEBUG does NOT provide an automated mechanism for
283	checking that all accesses to malloced memory stay within their
284	bounds. However, there are several add-ons and adaptations of this
285	or other mallocs available that do this.
286	*/
287
288	#ifndef MALLOC_DEBUG
289	#define MALLOC_DEBUG 0
290	#endif
291
292	#if USE_TCACHE
293	/ We want 64 entries. This is an arbitrary limit, which tunables can reduce. /
294	# define TCACHE_MAX_BINS 64
295	# define MAX_TCACHE_SIZE tidx2usize (TCACHE_MAX_BINS-1)
296
297	/ Only used to pre-fill the tunables. /
298	# define tidx2usize(idx) (((size_t) idx) * MALLOC_ALIGNMENT + MINSIZE - SIZE_SZ)
299
300	/ When "x" is from chunksize(). /
301	# define csize2tidx(x) (((x) - MINSIZE + MALLOC_ALIGNMENT - 1) / MALLOC_ALIGNMENT)
302	/ When "x" is a user-provided size. /
303	# define usize2tidx(x) csize2tidx (request2size (x))
304
305	/ With rounding and alignment, the bins are...*
306	idx 0 bytes 0..24 (64-bit) or 0..12 (32-bit)
307	idx 1 bytes 25..40 or 13..20
308	idx 2 bytes 41..56 or 21..28
309	etc. /*
310
311	/ This is another arbitrary limit, which tunables can change. Each*
312	tcache bin will hold at most this number of chunks. /*
313	# define TCACHE_FILL_COUNT 7
314
315	/ Maximum chunks in tcache bins for tunables. This value must fit the range*
316	of tcache->counts[] entries, else they may overflow. /*
317	# define MAX_TCACHE_COUNT UINT16_MAX
318	#endif
319
320	/ Safe-Linking:*
321	Use randomness from ASLR (mmap_base) to protect single-linked lists
322	of Fast-Bins and TCache. That is, mask the "next" pointers of the
323	lists' chunks, and also perform allocation alignment checks on them.
324	This mechanism reduces the risk of pointer hijacking, as was done with
325	Safe-Unlinking in the double-linked lists of Small-Bins.
326	It assumes a minimum page size of 4096 bytes (12 bits). Systems with
327	larger pages provide less entropy, although the pointer mangling
328	still works. /*
329	#define PROTECT_PTR(pos, ptr) \
330	((__typeof (ptr)) ((((size_t) pos) >> 12) ^ ((size_t) ptr)))
331	#define REVEAL_PTR(ptr) PROTECT_PTR (&ptr, ptr)
332
333	/*
334	The REALLOC_ZERO_BYTES_FREES macro controls the behavior of realloc (p, 0)
335	when p is nonnull. If the macro is nonzero, the realloc call returns NULL;
336	otherwise, the call returns what malloc (0) would. In either case,
337	p is freed. Glibc uses a nonzero REALLOC_ZERO_BYTES_FREES, which
338	implements common historical practice.
339
340	ISO C17 says the realloc call has implementation-defined behavior,
341	and it might not even free p.
342	*/
343
344	#ifndef REALLOC_ZERO_BYTES_FREES
345	#define REALLOC_ZERO_BYTES_FREES 1
346	#endif
347
348	/*
349	TRIM_FASTBINS controls whether free() of a very small chunk can
350	immediately lead to trimming. Setting to true (1) can reduce memory
351	footprint, but will almost always slow down programs that use a lot
352	of small chunks.
353
354	Define this only if you are willing to give up some speed to more
355	aggressively reduce system-level memory footprint when releasing
356	memory in programs that use many small chunks. You can get
357	essentially the same effect by setting MXFAST to 0, but this can
358	lead to even greater slowdowns in programs using many small chunks.
359	TRIM_FASTBINS is an in-between compile-time option, that disables
360	only those chunks bordering topmost memory from being placed in
361	fastbins.
362	*/
363
364	#ifndef TRIM_FASTBINS
365	#define TRIM_FASTBINS 0
366	#endif
367
368	/ Definition for getting more memory from the OS. /
369	#include "morecore.c"
370
371	#define MORECORE (*__glibc_morecore)
372	#define MORECORE_FAILURE 0
373
374	/ Memory tagging. /
375
376	/ Some systems support the concept of tagging (sometimes known as*
377	coloring) memory locations on a fine grained basis. Each memory
378	location is given a color (normally allocated randomly) and
379	pointers are also colored. When the pointer is dereferenced, the
380	pointer's color is checked against the memory's color and if they
381	differ the access is faulted (sometimes lazily).
382
383	We use this in glibc by maintaining a single color for the malloc
384	data structures that are interleaved with the user data and then
385	assigning separate colors for each block allocation handed out. In
386	this way simple buffer overruns will be rapidly detected. When
387	memory is freed, the memory is recolored back to the glibc default
388	so that simple use-after-free errors can also be detected.
389
390	If memory is reallocated the buffer is recolored even if the
391	address remains the same. This has a performance impact, but
392	guarantees that the old pointer cannot mistakenly be reused (code
393	that compares old against new will see a mismatch and will then
394	need to behave as though realloc moved the data to a new location).
395
396	Internal API for memory tagging support.
397
398	The aim is to keep the code for memory tagging support as close to
399	the normal APIs in glibc as possible, so that if tagging is not
400	enabled in the library, or is disabled at runtime then standard
401	operations can continue to be used. Support macros are used to do
402	this:
403
404	void tag_new_zero_region (void ptr, size_t size)
405
406	Allocates a new tag, colors the memory with that tag, zeros the
407	memory and returns a pointer that is correctly colored for that
408	location. The non-tagging version will simply call memset with 0.
409
410	void tag_region (void ptr, size_t size)
411
412	Color the region of memory pointed to by PTR and size SIZE with
413	the color of PTR. Returns the original pointer.
414
415	void tag_new_usable (void ptr)
416
417	Allocate a new random color and use it to color the user region of
418	a chunk; this may include data from the subsequent chunk's header
419	if tagging is sufficiently fine grained. Returns PTR suitably
420	recolored for accessing the memory there.
421
422	void tag_at (void ptr)
423
424	Read the current color of the memory at the address pointed to by
425	PTR (ignoring it's current color) and return PTR recolored to that
426	color. PTR must be valid address in all other respects. When
427	tagging is not enabled, it simply returns the original pointer.
428	*/
429
430	#ifdef USE_MTAG
431	static bool mtag_enabled = false;
432	static int mtag_mmap_flags = `0`;
433	#else
434	# define mtag_enabled false
435	# define mtag_mmap_flags 0
436	#endif
437
438	static __always_inline void *
439	tag_region (void *ptr, size_t size)
440	{
441	if (__glibc_unlikely (mtag_enabled))
442	return __libc_mtag_tag_region (p: ptr, n: size);
443	return ptr;
444	}
445
446	static __always_inline void *
447	tag_new_zero_region (void *ptr, size_t size)
448	{
449	if (__glibc_unlikely (mtag_enabled))
450	return __libc_mtag_tag_zero_region (p: __libc_mtag_new_tag (p: ptr), n: size);
451	return memset (s: ptr, c: `0`, n: size);
452	}
453
454	/ Defined later. /
455	static void *
456	tag_new_usable (void *ptr);
457
458	static __always_inline void *
459	tag_at (void *ptr)
460	{
461	if (__glibc_unlikely (mtag_enabled))
462	return __libc_mtag_address_get_tag (p: ptr);
463	return ptr;
464	}
465
466	#include <string.h>
467
468	/*
469	MORECORE-related declarations. By default, rely on sbrk
470	*/
471
472
473	/*
474	MORECORE is the name of the routine to call to obtain more memory
475	from the system. See below for general guidance on writing
476	alternative MORECORE functions, as well as a version for WIN32 and a
477	sample version for pre-OSX macos.
478	*/
479
480	#ifndef MORECORE
481	#define MORECORE sbrk
482	#endif
483
484	/*
485	MORECORE_FAILURE is the value returned upon failure of MORECORE
486	as well as mmap. Since it cannot be an otherwise valid memory address,
487	and must reflect values of standard sys calls, you probably ought not
488	try to redefine it.
489	*/
490
491	#ifndef MORECORE_FAILURE
492	#define MORECORE_FAILURE (-1)
493	#endif
494
495	/*
496	If MORECORE_CONTIGUOUS is true, take advantage of fact that
497	consecutive calls to MORECORE with positive arguments always return
498	contiguous increasing addresses. This is true of unix sbrk. Even
499	if not defined, when regions happen to be contiguous, malloc will
500	permit allocations spanning regions obtained from different
501	calls. But defining this when applicable enables some stronger
502	consistency checks and space efficiencies.
503	*/
504
505	#ifndef MORECORE_CONTIGUOUS
506	#define MORECORE_CONTIGUOUS 1
507	#endif
508
509	/*
510	Define MORECORE_CANNOT_TRIM if your version of MORECORE
511	cannot release space back to the system when given negative
512	arguments. This is generally necessary only if you are using
513	a hand-crafted MORECORE function that cannot handle negative arguments.
514	*/
515
516	/ #define MORECORE_CANNOT_TRIM /
517
518	/ MORECORE_CLEARS (default 1)*
519	The degree to which the routine mapped to MORECORE zeroes out
520	memory: never (0), only for newly allocated space (1) or always
521	(2). The distinction between (1) and (2) is necessary because on
522	some systems, if the application first decrements and then
523	increments the break value, the contents of the reallocated space
524	are unspecified.
525	*/
526
527	#ifndef MORECORE_CLEARS
528	# define MORECORE_CLEARS 1
529	#endif
530
531
532	/*
533	MMAP_AS_MORECORE_SIZE is the minimum mmap size argument to use if
534	sbrk fails, and mmap is used as a backup. The value must be a
535	multiple of page size. This backup strategy generally applies only
536	when systems have "holes" in address space, so sbrk cannot perform
537	contiguous expansion, but there is still space available on system.
538	On systems for which this is known to be useful (i.e. most linux
539	kernels), this occurs only when programs allocate huge amounts of
540	memory. Between this, and the fact that mmap regions tend to be
541	limited, the size should be large, to avoid too many mmap calls and
542	thus avoid running out of kernel resources. /*
543
544	#ifndef MMAP_AS_MORECORE_SIZE
545	#define MMAP_AS_MORECORE_SIZE (1024 * 1024)
546	#endif
547
548	/*
549	Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
550	large blocks.
551	*/
552
553	#ifndef HAVE_MREMAP
554	#define HAVE_MREMAP 0
555	#endif
556
557	/*
558	This version of malloc supports the standard SVID/XPG mallinfo
559	routine that returns a struct containing usage properties and
560	statistics. It should work on any SVID/XPG compliant system that has
561	a /usr/include/malloc.h defining struct mallinfo. (If you'd like to
562	install such a thing yourself, cut out the preliminary declarations
563	as described above and below and save them in a malloc.h file. But
564	there's no compelling reason to bother to do this.)
565
566	The main declaration needed is the mallinfo struct that is returned
567	(by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
568	bunch of fields that are not even meaningful in this version of
569	malloc. These fields are are instead filled by mallinfo() with
570	other numbers that might be of interest.
571	*/
572
573
574	/ ---------- description of public routines ------------ /
575
576	#if IS_IN (libc)
577	/*
578	malloc(size_t n)
579	Returns a pointer to a newly allocated chunk of at least n bytes, or null
580	if no space is available. Additionally, on failure, errno is
581	set to ENOMEM on ANSI C systems.
582
583	If n is zero, malloc returns a minimum-sized chunk. (The minimum
584	size is 16 bytes on most 32bit systems, and 24 or 32 bytes on 64bit
585	systems.) On most systems, size_t is an unsigned type, so calls
586	with negative arguments are interpreted as requests for huge amounts
587	of space, which will often fail. The maximum supported value of n
588	differs across systems, but is in all cases less than the maximum
589	representable value of a size_t.
590	*/
591	void* __libc_malloc(size_t);
592	libc_hidden_proto (__libc_malloc)
593
594	/*
595	free(void p)*
596	Releases the chunk of memory pointed to by p, that had been previously
597	allocated using malloc or a related routine such as realloc.
598	It has no effect if p is null. It can have arbitrary (i.e., bad!)
599	effects if p has already been freed.
600
601	Unless disabled (using mallopt), freeing very large spaces will
602	when possible, automatically trigger operations that give
603	back unused memory to the system, thus reducing program footprint.
604	*/
605	void __libc_free(void*);
606	libc_hidden_proto (__libc_free)
607
608	/*
609	calloc(size_t n_elements, size_t element_size);
610	Returns a pointer to n_elements element_size bytes, with all locations*
611	set to zero.
612	*/
613	void* __libc_calloc(size_t, size_t);
614
615	/*
616	realloc(void p, size_t n)*
617	Returns a pointer to a chunk of size n that contains the same data
618	as does chunk p up to the minimum of (n, p's size) bytes, or null
619	if no space is available.
620
621	The returned pointer may or may not be the same as p. The algorithm
622	prefers extending p when possible, otherwise it employs the
623	equivalent of a malloc-copy-free sequence.
624
625	If p is null, realloc is equivalent to malloc.
626
627	If space is not available, realloc returns null, errno is set (if on
628	ANSI) and p is NOT freed.
629
630	if n is for fewer bytes than already held by p, the newly unused
631	space is lopped off and freed if possible. Unless the #define
632	REALLOC_ZERO_BYTES_FREES is set, realloc with a size argument of
633	zero (re)allocates a minimum-sized chunk.
634
635	Large chunks that were internally obtained via mmap will always be
636	grown using malloc-copy-free sequences unless the system supports
637	MREMAP (currently only linux).
638
639	The old unix realloc convention of allowing the last-free'd chunk
640	to be used as an argument to realloc is not supported.
641	*/
642	void* __libc_realloc(void*, size_t);
643	libc_hidden_proto (__libc_realloc)
644
645	/*
646	memalign(size_t alignment, size_t n);
647	Returns a pointer to a newly allocated chunk of n bytes, aligned
648	in accord with the alignment argument.
649
650	The alignment argument should be a power of two. If the argument is
651	not a power of two, the nearest greater power is used.
652	8-byte alignment is guaranteed by normal malloc calls, so don't
653	bother calling memalign with an argument of 8 or less.
654
655	Overreliance on memalign is a sure way to fragment space.
656	*/
657	void* __libc_memalign(size_t, size_t);
658	libc_hidden_proto (__libc_memalign)
659
660	/*
661	valloc(size_t n);
662	Equivalent to memalign(pagesize, n), where pagesize is the page
663	size of the system. If the pagesize is unknown, 4096 is used.
664	*/
665	void* __libc_valloc(size_t);
666
667
668
669	/*
670	mallinfo()
671	Returns (by copy) a struct containing various summary statistics:
672
673	arena: current total non-mmapped bytes allocated from system
674	ordblks: the number of free chunks
675	smblks: the number of fastbin blocks (i.e., small chunks that
676	have been freed but not reused or consolidated)
677	hblks: current number of mmapped regions
678	hblkhd: total bytes held in mmapped regions
679	usmblks: always 0
680	fsmblks: total bytes held in fastbin blocks
681	uordblks: current total allocated space (normal or mmapped)
682	fordblks: total free space
683	keepcost: the maximum number of bytes that could ideally be released
684	back to system via malloc_trim. ("ideally" means that
685	it ignores page restrictions etc.)
686
687	Because these fields are ints, but internal bookkeeping may
688	be kept as longs, the reported values may wrap around zero and
689	thus be inaccurate.
690	*/
691	struct mallinfo2 __libc_mallinfo2(void);
692	libc_hidden_proto (__libc_mallinfo2)
693
694	struct mallinfo __libc_mallinfo(void);
695
696
697	/*
698	pvalloc(size_t n);
699	Equivalent to valloc(minimum-page-that-holds(n)), that is,
700	round up n to nearest pagesize.
701	*/
702	void* __libc_pvalloc(size_t);
703
704	/*
705	malloc_trim(size_t pad);
706
707	If possible, gives memory back to the system (via negative
708	arguments to sbrk) if there is unused memory at the `high' end of
709	the malloc pool. You can call this after freeing large blocks of
710	memory to potentially reduce the system-level memory requirements
711	of a program. However, it cannot guarantee to reduce memory. Under
712	some allocation patterns, some large free blocks of memory will be
713	locked between two used chunks, so they cannot be given back to
714	the system.
715
716	The `pad' argument to malloc_trim represents the amount of free
717	trailing space to leave untrimmed. If this argument is zero,
718	only the minimum amount of memory to maintain internal data
719	structures will be left (one page or less). Non-zero arguments
720	can be supplied to maintain enough trailing space to service
721	future expected allocations without having to re-obtain memory
722	from the system.
723
724	Malloc_trim returns 1 if it actually released any memory, else 0.
725	On systems that do not support "negative sbrks", it will always
726	return 0.
727	*/
728	int __malloc_trim(size_t);
729
730	/*
731	malloc_usable_size(void p);*
732
733	Returns the number of bytes you can actually use in
734	an allocated chunk, which may be more than you requested (although
735	often not) due to alignment and minimum size constraints.
736	You can use this many bytes without worrying about
737	overwriting other allocated objects. This is not a particularly great
738	programming practice. malloc_usable_size can be more useful in
739	debugging and assertions, for example:
740
741	p = malloc(n);
742	assert(malloc_usable_size(p) >= 256);
743
744	*/
745	size_t __malloc_usable_size(void*);
746
747	/*
748	malloc_stats();
749	Prints on stderr the amount of space obtained from the system (both
750	via sbrk and mmap), the maximum amount (which may be more than
751	current if malloc_trim and/or munmap got called), and the current
752	number of bytes allocated via malloc (or realloc, etc) but not yet
753	freed. Note that this is the number of bytes allocated, not the
754	number requested. It will be larger than the number requested
755	because of alignment and bookkeeping overhead. Because it includes
756	alignment wastage as being in use, this figure may be greater than
757	zero even when no user-level chunks are allocated.
758
759	The reported current and maximum system memory can be inaccurate if
760	a program makes other calls to system memory allocation functions
761	(normally sbrk) outside of malloc.
762
763	malloc_stats prints only the most commonly interesting statistics.
764	More information can be obtained by calling mallinfo.
765
766	*/
767	void __malloc_stats(void);
768
769	/*
770	posix_memalign(void memptr, size_t alignment, size_t size);
771
772	POSIX wrapper like memalign(), checking for validity of size.
773	*/
774	int __posix_memalign(void **, size_t, size_t);
775	#endif /* IS_IN (libc) */
776
777	/*
778	mallopt(int parameter_number, int parameter_value)
779	Sets tunable parameters The format is to provide a
780	(parameter-number, parameter-value) pair. mallopt then sets the
781	corresponding parameter to the argument value if it can (i.e., so
782	long as the value is meaningful), and returns 1 if successful else
783	0. SVID/XPG/ANSI defines four standard param numbers for mallopt,
784	normally defined in malloc.h. Only one of these (M_MXFAST) is used
785	in this malloc. The others (M_NLBLKS, M_GRAIN, M_KEEP) don't apply,
786	so setting them has no effect. But this malloc also supports four
787	other options in mallopt. See below for details. Briefly, supported
788	parameters are as follows (listed defaults are for "typical"
789	configurations).
790
791	Symbol param # default allowed param values
792	M_MXFAST 1 64 0-80 (0 disables fastbins)
793	M_TRIM_THRESHOLD -1 1281024 any (-1U disables trimming)*
794	M_TOP_PAD -2 0 any
795	M_MMAP_THRESHOLD -3 1281024 any (or 0 if no MMAP support)*
796	M_MMAP_MAX -4 65536 any (0 disables use of mmap)
797	*/
798	int __libc_mallopt(int, int);
799	#if IS_IN (libc)
800	libc_hidden_proto (__libc_mallopt)
801	#endif
802
803	/ mallopt tuning options /
804
805	/*
806	M_MXFAST is the maximum request size used for "fastbins", special bins
807	that hold returned chunks without consolidating their spaces. This
808	enables future requests for chunks of the same size to be handled
809	very quickly, but can increase fragmentation, and thus increase the
810	overall memory footprint of a program.
811
812	This malloc manages fastbins very conservatively yet still
813	efficiently, so fragmentation is rarely a problem for values less
814	than or equal to the default. The maximum supported value of MXFAST
815	is 80. You wouldn't want it any higher than this anyway. Fastbins
816	are designed especially for use with many small structs, objects or
817	strings -- the default handles structs/objects/arrays with sizes up
818	to 8 4byte fields, or small strings representing words, tokens,
819	etc. Using fastbins for larger objects normally worsens
820	fragmentation without improving speed.
821
822	M_MXFAST is set in REQUEST size units. It is internally used in
823	chunksize units, which adds padding and alignment. You can reduce
824	M_MXFAST to 0 to disable all use of fastbins. This causes the malloc
825	algorithm to be a closer approximation of fifo-best-fit in all cases,
826	not just for larger requests, but will generally cause it to be
827	slower.
828	*/
829
830
831	/ M_MXFAST is a standard SVID/XPG tuning option, usually listed in malloc.h /
832	#ifndef M_MXFAST
833	#define M_MXFAST 1
834	#endif
835
836	#ifndef DEFAULT_MXFAST
837	#define DEFAULT_MXFAST (64 * SIZE_SZ / 4)
838	#endif
839
840
841	/*
842	M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
843	to keep before releasing via malloc_trim in free().
844
845	Automatic trimming is mainly useful in long-lived programs.
846	Because trimming via sbrk can be slow on some systems, and can
847	sometimes be wasteful (in cases where programs immediately
848	afterward allocate more large chunks) the value should be high
849	enough so that your overall system performance would improve by
850	releasing this much memory.
851
852	The trim threshold and the mmap control parameters (see below)
853	can be traded off with one another. Trimming and mmapping are
854	two different ways of releasing unused memory back to the
855	system. Between these two, it is often possible to keep
856	system-level demands of a long-lived program down to a bare
857	minimum. For example, in one test suite of sessions measuring
858	the XF86 X server on Linux, using a trim threshold of 128K and a
859	mmap threshold of 192K led to near-minimal long term resource
860	consumption.
861
862	If you are using this malloc in a long-lived program, it should
863	pay to experiment with these values. As a rough guide, you
864	might set to a value close to the average size of a process
865	(program) running on your system. Releasing this much memory
866	would allow such a process to run in memory. Generally, it's
867	worth it to tune for trimming rather tham memory mapping when a
868	program undergoes phases where several large chunks are
869	allocated and released in ways that can reuse each other's
870	storage, perhaps mixed with phases where there are no such
871	chunks at all. And in well-behaved long-lived programs,
872	controlling release of large blocks via trimming versus mapping
873	is usually faster.
874
875	However, in most programs, these parameters serve mainly as
876	protection against the system-level effects of carrying around
877	massive amounts of unneeded memory. Since frequent calls to
878	sbrk, mmap, and munmap otherwise degrade performance, the default
879	parameters are set to relatively high values that serve only as
880	safeguards.
881
882	The trim value It must be greater than page size to have any useful
883	effect. To disable trimming completely, you can set to
884	(unsigned long)(-1)
885
886	Trim settings interact with fastbin (MXFAST) settings: Unless
887	TRIM_FASTBINS is defined, automatic trimming never takes place upon
888	freeing a chunk with size less than or equal to MXFAST. Trimming is
889	instead delayed until subsequent freeing of larger chunks. However,
890	you can still force an attempted trim by calling malloc_trim.
891
892	Also, trimming is not generally possible in cases where
893	the main arena is obtained via mmap.
894
895	Note that the trick some people use of mallocing a huge space and
896	then freeing it at program startup, in an attempt to reserve system
897	memory, doesn't have the intended effect under automatic trimming,
898	since that memory will immediately be returned to the system.
899	*/
900
901	#define M_TRIM_THRESHOLD -1
902
903	#ifndef DEFAULT_TRIM_THRESHOLD
904	#define DEFAULT_TRIM_THRESHOLD (128 * 1024)
905	#endif
906
907	/*
908	M_TOP_PAD is the amount of extra `padding' space to allocate or
909	retain whenever sbrk is called. It is used in two ways internally:
910
911	* When sbrk is called to extend the top of the arena to satisfy
912	a new malloc request, this much padding is added to the sbrk
913	request.
914
915	* When malloc_trim is called automatically from free(),
916	it is used as the `pad' argument.
917
918	In both cases, the actual amount of padding is rounded
919	so that the end of the arena is always a system page boundary.
920
921	The main reason for using padding is to avoid calling sbrk so
922	often. Having even a small pad greatly reduces the likelihood
923	that nearly every malloc request during program start-up (or
924	after trimming) will invoke sbrk, which needlessly wastes
925	time.
926
927	Automatic rounding-up to page-size units is normally sufficient
928	to avoid measurable overhead, so the default is 0. However, in
929	systems where sbrk is relatively slow, it can pay to increase
930	this value, at the expense of carrying around more memory than
931	the program needs.
932	*/
933
934	#define M_TOP_PAD -2
935
936	#ifndef DEFAULT_TOP_PAD
937	#define DEFAULT_TOP_PAD (0)
938	#endif
939
940	/*
941	MMAP_THRESHOLD_MAX and _MIN are the bounds on the dynamically
942	adjusted MMAP_THRESHOLD.
943	*/
944
945	#ifndef DEFAULT_MMAP_THRESHOLD_MIN
946	#define DEFAULT_MMAP_THRESHOLD_MIN (128 * 1024)
947	#endif
948
949	#ifndef DEFAULT_MMAP_THRESHOLD_MAX
950	/ For 32-bit platforms we cannot increase the maximum mmap*
951	threshold much because it is also the minimum value for the
952	maximum heap size and its alignment. Going above 512k (i.e., 1M
953	for new heaps) wastes too much address space. /*
954	# if __WORDSIZE == 32
955	# define DEFAULT_MMAP_THRESHOLD_MAX (512 * 1024)
956	# else
957	# define DEFAULT_MMAP_THRESHOLD_MAX (4 * 1024 * 1024 * sizeof(long))
958	# endif
959	#endif
960
961	/*
962	M_MMAP_THRESHOLD is the request size threshold for using mmap()
963	to service a request. Requests of at least this size that cannot
964	be allocated using already-existing space will be serviced via mmap.
965	(If enough normal freed space already exists it is used instead.)
966
967	Using mmap segregates relatively large chunks of memory so that
968	they can be individually obtained and released from the host
969	system. A request serviced through mmap is never reused by any
970	other request (at least not directly; the system may just so
971	happen to remap successive requests to the same locations).
972
973	Segregating space in this way has the benefits that:
974
975	1. Mmapped space can ALWAYS be individually released back
976	to the system, which helps keep the system level memory
977	demands of a long-lived program low.
978	2. Mapped memory can never become `locked' between
979	other chunks, as can happen with normally allocated chunks, which
980	means that even trimming via malloc_trim would not release them.
981	3. On some systems with "holes" in address spaces, mmap can obtain
982	memory that sbrk cannot.
983
984	However, it has the disadvantages that:
985
986	1. The space cannot be reclaimed, consolidated, and then
987	used to service later requests, as happens with normal chunks.
988	2. It can lead to more wastage because of mmap page alignment
989	requirements
990	3. It causes malloc performance to be more dependent on host
991	system memory management support routines which may vary in
992	implementation quality and may impose arbitrary
993	limitations. Generally, servicing a request via normal
994	malloc steps is faster than going through a system's mmap.
995
996	The advantages of mmap nearly always outweigh disadvantages for
997	"large" chunks, but the value of "large" varies across systems. The
998	default is an empirically derived value that works well in most
999	systems.
1000
1001
1002	Update in 2006:
1003	The above was written in 2001. Since then the world has changed a lot.
1004	Memory got bigger. Applications got bigger. The virtual address space
1005	layout in 32 bit linux changed.
1006
1007	In the new situation, brk() and mmap space is shared and there are no
1008	artificial limits on brk size imposed by the kernel. What is more,
1009	applications have started using transient allocations larger than the
1010	128Kb as was imagined in 2001.
1011
1012	The price for mmap is also high now; each time glibc mmaps from the
1013	kernel, the kernel is forced to zero out the memory it gives to the
1014	application. Zeroing memory is expensive and eats a lot of cache and
1015	memory bandwidth. This has nothing to do with the efficiency of the
1016	virtual memory system, by doing mmap the kernel just has no choice but
1017	to zero.
1018
1019	In 2001, the kernel had a maximum size for brk() which was about 800
1020	megabytes on 32 bit x86, at that point brk() would hit the first
1021	mmaped shared libraries and couldn't expand anymore. With current 2.6
1022	kernels, the VA space layout is different and brk() and mmap
1023	both can span the entire heap at will.
1024
1025	Rather than using a static threshold for the brk/mmap tradeoff,
1026	we are now using a simple dynamic one. The goal is still to avoid
1027	fragmentation. The old goals we kept are
1028	1) try to get the long lived large allocations to use mmap()
1029	2) really large allocations should always use mmap()
1030	and we're adding now:
1031	3) transient allocations should use brk() to avoid forcing the kernel
1032	having to zero memory over and over again
1033
1034	The implementation works with a sliding threshold, which is by default
1035	limited to go between 128Kb and 32Mb (64Mb for 64 bitmachines) and starts
1036	out at 128Kb as per the 2001 default.
1037
1038	This allows us to satisfy requirement 1) under the assumption that long
1039	lived allocations are made early in the process' lifespan, before it has
1040	started doing dynamic allocations of the same size (which will
1041	increase the threshold).
1042
1043	The upperbound on the threshold satisfies requirement 2)
1044
1045	The threshold goes up in value when the application frees memory that was
1046	allocated with the mmap allocator. The idea is that once the application
1047	starts freeing memory of a certain size, it's highly probable that this is
1048	a size the application uses for transient allocations. This estimator
1049	is there to satisfy the new third requirement.
1050
1051	*/
1052
1053	#define M_MMAP_THRESHOLD -3
1054
1055	#ifndef DEFAULT_MMAP_THRESHOLD
1056	#define DEFAULT_MMAP_THRESHOLD DEFAULT_MMAP_THRESHOLD_MIN
1057	#endif
1058
1059	/*
1060	M_MMAP_MAX is the maximum number of requests to simultaneously
1061	service using mmap. This parameter exists because
1062	some systems have a limited number of internal tables for
1063	use by mmap, and using more than a few of them may degrade
1064	performance.
1065
1066	The default is set to a value that serves only as a safeguard.
1067	Setting to 0 disables use of mmap for servicing large requests.
1068	*/
1069
1070	#define M_MMAP_MAX -4
1071
1072	#ifndef DEFAULT_MMAP_MAX
1073	#define DEFAULT_MMAP_MAX (65536)
1074	#endif
1075
1076	#include <malloc.h>
1077
1078	#ifndef RETURN_ADDRESS
1079	#define RETURN_ADDRESS(X_) (NULL)
1080	#endif
1081
1082	/ Forward declarations. /
1083	struct malloc_chunk;
1084	typedef struct malloc_chunk* mchunkptr;
1085
1086	/ Internal routines. /
1087
1088	static void* _int_malloc(mstate, size_t);
1089	static void _int_free(mstate, mchunkptr, int);
1090	static void _int_free_merge_chunk (mstate, mchunkptr, INTERNAL_SIZE_T);
1091	static INTERNAL_SIZE_T _int_free_create_chunk (mstate,
1092	mchunkptr, INTERNAL_SIZE_T,
1093	mchunkptr, INTERNAL_SIZE_T);
1094	static void _int_free_maybe_consolidate (mstate, INTERNAL_SIZE_T);
1095	static void* _int_realloc(mstate, mchunkptr, INTERNAL_SIZE_T,
1096	INTERNAL_SIZE_T);
1097	static void* _int_memalign(mstate, size_t, size_t);
1098	#if IS_IN (libc)
1099	static void* _mid_memalign(size_t, size_t, void *);
1100	#endif
1101
1102	static void malloc_printerr(const char str) __attribute__* ((noreturn));
1103
1104	static void munmap_chunk(mchunkptr p);
1105	#if HAVE_MREMAP
1106	static mchunkptr mremap_chunk(mchunkptr p, size_t new_size);
1107	#endif
1108
1109	static size_t musable (void *mem);
1110
1111	/ ------------------ MMAP support ------------------ /
1112
1113
1114	#include <fcntl.h>
1115	#include <sys/mman.h>
1116
1117	#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
1118	# define MAP_ANONYMOUS MAP_ANON
1119	#endif
1120
1121	#define MMAP(addr, size, prot, flags) \
1122	__mmap((addr), (size), (prot), (flags)\|MAP_ANONYMOUS\|MAP_PRIVATE, -1, 0)
1123
1124
1125	/*
1126	----------------------- Chunk representations -----------------------
1127	*/
1128
1129
1130	/*
1131	This struct declaration is misleading (but accurate and necessary).
1132	It declares a "view" into memory allowing access to necessary
1133	fields at known offsets from a given base. See explanation below.
1134	*/
1135
1136	struct malloc_chunk {
1137
1138	INTERNAL_SIZE_T mchunk_prev_size; / Size of previous chunk (if free). /
1139	INTERNAL_SIZE_T mchunk_size; / Size in bytes, including overhead. /
1140
1141	struct malloc_chunk* fd; / double links -- used only if free. /
1142	struct malloc_chunk* bk;
1143
1144	/ Only used for large blocks: pointer to next larger size. /
1145	struct malloc_chunk* fd_nextsize; / double links -- used only if free. /
1146	struct malloc_chunk* bk_nextsize;
1147	};
1148
1149
1150	/*
1151	malloc_chunk details:
1152
1153	(The following includes lightly edited explanations by Colin Plumb.)
1154
1155	Chunks of memory are maintained using a `boundary tag' method as
1156	described in e.g., Knuth or Standish. (See the paper by Paul
1157	Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
1158	survey of such techniques.) Sizes of free chunks are stored both
1159	in the front of each chunk and at the end. This makes
1160	consolidating fragmented chunks into bigger chunks very fast. The
1161	size fields also hold bits representing whether chunks are free or
1162	in use.
1163
1164	An allocated chunk looks like this:
1165
1166
1167	chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1168	\| Size of previous chunk, if unallocated (P clear) \|
1169	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1170	\| Size of chunk, in bytes \|A\|M\|P\|
1171	mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1172	\| User data starts here... .
1173	. .
1174	. (malloc_usable_size() bytes) .
1175	. \|
1176	nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1177	\| (size of chunk, but used for application data) \|
1178	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1179	\| Size of next chunk, in bytes \|A\|0\|1\|
1180	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1181
1182	Where "chunk" is the front of the chunk for the purpose of most of
1183	the malloc code, but "mem" is the pointer that is returned to the
1184	user. "Nextchunk" is the beginning of the next contiguous chunk.
1185
1186	Chunks always begin on even word boundaries, so the mem portion
1187	(which is returned to the user) is also on an even word boundary, and
1188	thus at least double-word aligned.
1189
1190	Free chunks are stored in circular doubly-linked lists, and look like this:
1191
1192	chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1193	\| Size of previous chunk, if unallocated (P clear) \|
1194	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1195	`head:' \| Size of chunk, in bytes \|A\|0\|P\|
1196	mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1197	\| Forward pointer to next chunk in list \|
1198	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1199	\| Back pointer to previous chunk in list \|
1200	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1201	\| Unused space (may be 0 bytes long) .
1202	. .
1203	. \|
1204	nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1205	`foot:' \| Size of chunk, in bytes \|
1206	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1207	\| Size of next chunk, in bytes \|A\|0\|0\|
1208	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1209
1210	The P (PREV_INUSE) bit, stored in the unused low-order bit of the
1211	chunk size (which is always a multiple of two words), is an in-use
1212	bit for the previous* chunk. If that bit is clear, then the*
1213	word before the current chunk size contains the previous chunk
1214	size, and can be used to find the front of the previous chunk.
1215	The very first chunk allocated always has this bit set,
1216	preventing access to non-existent (or non-owned) memory. If
1217	prev_inuse is set for any given chunk, then you CANNOT determine
1218	the size of the previous chunk, and might even get a memory
1219	addressing fault when trying to do so.
1220
1221	The A (NON_MAIN_ARENA) bit is cleared for chunks on the initial,
1222	main arena, described by the main_arena variable. When additional
1223	threads are spawned, each thread receives its own arena (up to a
1224	configurable limit, after which arenas are reused for multiple
1225	threads), and the chunks in these arenas have the A bit set. To
1226	find the arena for a chunk on such a non-main arena, heap_for_ptr
1227	performs a bit mask operation and indirection through the ar_ptr
1228	member of the per-heap header heap_info (see arena.c).
1229
1230	Note that the `foot' of the current chunk is actually represented
1231	as the prev_size of the NEXT chunk. This makes it easier to
1232	deal with alignments etc but can be very confusing when trying
1233	to extend or adapt this code.
1234
1235	The three exceptions to all this are:
1236
1237	1. The special chunk `top' doesn't bother using the
1238	trailing size field since there is no next contiguous chunk
1239	that would have to index off it. After initialization, `top'
1240	is forced to always exist. If it would become less than
1241	MINSIZE bytes long, it is replenished.
1242
1243	2. Chunks allocated via mmap, which have the second-lowest-order
1244	bit M (IS_MMAPPED) set in their size fields. Because they are
1245	allocated one-by-one, each must contain its own trailing size
1246	field. If the M bit is set, the other bits are ignored
1247	(because mmapped chunks are neither in an arena, nor adjacent
1248	to a freed chunk). The M bit is also used for chunks which
1249	originally came from a dumped heap via malloc_set_state in
1250	hooks.c.
1251
1252	3. Chunks in fastbins are treated as allocated chunks from the
1253	point of view of the chunk allocator. They are consolidated
1254	with their neighbors only in bulk, in malloc_consolidate.
1255	*/
1256
1257	/*
1258	---------- Size and alignment checks and conversions ----------
1259	*/
1260
1261	/ Conversion from malloc headers to user pointers, and back. When*
1262	using memory tagging the user data and the malloc data structure
1263	headers have distinct tags. Converting fully from one to the other
1264	involves extracting the tag at the other address and creating a
1265	suitable pointer using it. That can be quite expensive. There are
1266	cases when the pointers are not dereferenced (for example only used
1267	for alignment check) so the tags are not relevant, and there are
1268	cases when user data is not tagged distinctly from malloc headers
1269	(user data is untagged because tagging is done late in malloc and
1270	early in free). User memory tagging across internal interfaces:
1271
1272	sysmalloc: Returns untagged memory.
1273	_int_malloc: Returns untagged memory.
1274	_int_free: Takes untagged memory.
1275	_int_memalign: Returns untagged memory.
1276	_int_memalign: Returns untagged memory.
1277	_mid_memalign: Returns tagged memory.
1278	_int_realloc: Takes and returns tagged memory.
1279	*/
1280
1281	/ The chunk header is two SIZE_SZ elements, but this is used widely, so*
1282	we define it here for clarity later. /*
1283	#define CHUNK_HDR_SZ (2 * SIZE_SZ)
1284
1285	/ Convert a chunk address to a user mem pointer without correcting*
1286	the tag. /*
1287	#define chunk2mem(p) ((void)((char)(p) + CHUNK_HDR_SZ))
1288
1289	/ Convert a chunk address to a user mem pointer and extract the right tag. /
1290	#define chunk2mem_tag(p) ((void)tag_at ((char)(p) + CHUNK_HDR_SZ))
1291
1292	/ Convert a user mem pointer to a chunk address and extract the right tag. /
1293	#define mem2chunk(mem) ((mchunkptr)tag_at (((char*)(mem) - CHUNK_HDR_SZ)))
1294
1295	/ The smallest possible chunk /
1296	#define MIN_CHUNK_SIZE (offsetof(struct malloc_chunk, fd_nextsize))
1297
1298	/ The smallest size we can malloc is an aligned minimal chunk /
1299
1300	#define MINSIZE \
1301	(unsigned long)(((MIN_CHUNK_SIZE+MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK))
1302
1303	/ Check if m has acceptable alignment /
1304
1305	#define aligned_OK(m) (((unsigned long)(m) & MALLOC_ALIGN_MASK) == 0)
1306
1307	#define misaligned_chunk(p) \
1308	((uintptr_t)(MALLOC_ALIGNMENT == CHUNK_HDR_SZ ? (p) : chunk2mem (p)) \
1309	& MALLOC_ALIGN_MASK)
1310
1311	/ pad request bytes into a usable size -- internal version /
1312	/ Note: This must be a macro that evaluates to a compile time constant*
1313	if passed a literal constant. /*
1314	#define request2size(req) \
1315	(((req) + SIZE_SZ + MALLOC_ALIGN_MASK < MINSIZE) ? \
1316	MINSIZE : \
1317	((req) + SIZE_SZ + MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK)
1318
1319	/ Check if REQ overflows when padded and aligned and if the resulting*
1320	value is less than PTRDIFF_T. Returns the requested size or
1321	MINSIZE in case the value is less than MINSIZE, or 0 if any of the
1322	previous checks fail. /*
1323	static inline size_t
1324	checked_request2size (size_t req) __nonnull (`1`)
1325	{
1326	if (__glibc_unlikely (req > PTRDIFF_MAX))
1327	return `0`;
1328
1329	/ When using tagged memory, we cannot share the end of the user*
1330	block with the header for the next chunk, so ensure that we
1331	allocate blocks that are rounded up to the granule size. Take
1332	care not to overflow from close to MAX_SIZE_T to a small
1333	number. Ideally, this would be part of request2size(), but that
1334	must be a macro that produces a compile time constant if passed
1335	a constant literal. /*
1336	if (__glibc_unlikely (mtag_enabled))
1337	{
1338	/ Ensure this is not evaluated if !mtag_enabled, see gcc PR 99551. /
1339	asm ("");
1340
1341	req = (req + (__MTAG_GRANULE_SIZE - `1`)) &
1342	~(size_t)(__MTAG_GRANULE_SIZE - `1`);
1343	}
1344
1345	return request2size (req);
1346	}
1347
1348	/*
1349	--------------- Physical chunk operations ---------------
1350	*/
1351
1352
1353	/ size field is or'ed with PREV_INUSE when previous adjacent chunk in use /
1354	#define PREV_INUSE 0x1
1355
1356	/ extract inuse bit of previous chunk /
1357	#define prev_inuse(p) ((p)->mchunk_size & PREV_INUSE)
1358
1359
1360	/ size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() /
1361	#define IS_MMAPPED 0x2
1362
1363	/ check for mmap()'ed chunk /
1364	#define chunk_is_mmapped(p) ((p)->mchunk_size & IS_MMAPPED)
1365
1366
1367	/ size field is or'ed with NON_MAIN_ARENA if the chunk was obtained*
1368	from a non-main arena. This is only set immediately before handing
1369	the chunk to the user, if necessary. /*
1370	#define NON_MAIN_ARENA 0x4
1371
1372	/ Check for chunk from main arena. /
1373	#define chunk_main_arena(p) (((p)->mchunk_size & NON_MAIN_ARENA) == 0)
1374
1375	/ Mark a chunk as not being on the main arena. /
1376	#define set_non_main_arena(p) ((p)->mchunk_size \|= NON_MAIN_ARENA)
1377
1378
1379	/*
1380	Bits to mask off when extracting size
1381
1382	Note: IS_MMAPPED is intentionally not masked off from size field in
1383	macros for which mmapped chunks should never be seen. This should
1384	cause helpful core dumps to occur if it is tried by accident by
1385	people extending or adapting this malloc.
1386	*/
1387	#define SIZE_BITS (PREV_INUSE \| IS_MMAPPED \| NON_MAIN_ARENA)
1388
1389	/ Get size, ignoring use bits /
1390	#define chunksize(p) (chunksize_nomask (p) & ~(SIZE_BITS))
1391
1392	/ Like chunksize, but do not mask SIZE_BITS. /
1393	#define chunksize_nomask(p) ((p)->mchunk_size)
1394
1395	/ Ptr to next physical malloc_chunk. /
1396	#define next_chunk(p) ((mchunkptr) (((char *) (p)) + chunksize (p)))
1397
1398	/ Size of the chunk below P. Only valid if !prev_inuse (P). /
1399	#define prev_size(p) ((p)->mchunk_prev_size)
1400
1401	/ Set the size of the chunk below P. Only valid if !prev_inuse (P). /
1402	#define set_prev_size(p, sz) ((p)->mchunk_prev_size = (sz))
1403
1404	/ Ptr to previous physical malloc_chunk. Only valid if !prev_inuse (P). /
1405	#define prev_chunk(p) ((mchunkptr) (((char *) (p)) - prev_size (p)))
1406
1407	/ Treat space at ptr + offset as a chunk /
1408	#define chunk_at_offset(p, s) ((mchunkptr) (((char *) (p)) + (s)))
1409
1410	/ extract p's inuse bit /
1411	#define inuse(p) \
1412	((((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size) & PREV_INUSE)
1413
1414	/ set/clear chunk as being inuse without otherwise disturbing /
1415	#define set_inuse(p) \
1416	((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size \|= PREV_INUSE
1417
1418	#define clear_inuse(p) \
1419	((mchunkptr) (((char *) (p)) + chunksize (p)))->mchunk_size &= ~(PREV_INUSE)
1420
1421
1422	/ check/set/clear inuse bits in known places /
1423	#define inuse_bit_at_offset(p, s) \
1424	(((mchunkptr) (((char *) (p)) + (s)))->mchunk_size & PREV_INUSE)
1425
1426	#define set_inuse_bit_at_offset(p, s) \
1427	(((mchunkptr) (((char *) (p)) + (s)))->mchunk_size \|= PREV_INUSE)
1428
1429	#define clear_inuse_bit_at_offset(p, s) \
1430	(((mchunkptr) (((char *) (p)) + (s)))->mchunk_size &= ~(PREV_INUSE))
1431
1432
1433	/ Set size at head, without disturbing its use bit /
1434	#define set_head_size(p, s) ((p)->mchunk_size = (((p)->mchunk_size & SIZE_BITS) \| (s)))
1435
1436	/ Set size/use field /
1437	#define set_head(p, s) ((p)->mchunk_size = (s))
1438
1439	/ Set size at footer (only when chunk is not in use) /
1440	#define set_foot(p, s) (((mchunkptr) ((char *) (p) + (s)))->mchunk_prev_size = (s))
1441
1442	#pragma GCC poison mchunk_size
1443	#pragma GCC poison mchunk_prev_size
1444
1445	/ This is the size of the real usable data in the chunk. Not valid for*
1446	dumped heap chunks. /*
1447	#define memsize(p) \
1448	(__MTAG_GRANULE_SIZE > SIZE_SZ && __glibc_unlikely (mtag_enabled) ? \
1449	chunksize (p) - CHUNK_HDR_SZ : \
1450	chunksize (p) - CHUNK_HDR_SZ + (chunk_is_mmapped (p) ? 0 : SIZE_SZ))
1451
1452	/ If memory tagging is enabled the layout changes to accommodate the granule*
1453	size, this is wasteful for small allocations so not done by default.
1454	Both the chunk header and user data has to be granule aligned. /*
1455	_Static_assert (__MTAG_GRANULE_SIZE <= CHUNK_HDR_SZ,
1456	"memory tagging is not supported with large granule.");
1457
1458	static __always_inline void *
1459	tag_new_usable (void *ptr)
1460	{
1461	if (__glibc_unlikely (mtag_enabled) && ptr)
1462	{
1463	mchunkptr cp = mem2chunk(ptr);
1464	ptr = __libc_mtag_tag_region (p: __libc_mtag_new_tag (p: ptr), memsize (cp));
1465	}
1466	return ptr;
1467	}
1468
1469	/*
1470	-------------------- Internal data structures --------------------
1471
1472	All internal state is held in an instance of malloc_state defined
1473	below. There are no other static variables, except in two optional
1474	cases:
1475	* If USE_MALLOC_LOCK is defined, the mALLOC_MUTEx declared above.
1476	* If mmap doesn't support MAP_ANONYMOUS, a dummy file descriptor
1477	for mmap.
1478
1479	Beware of lots of tricks that minimize the total bookkeeping space
1480	requirements. The result is a little over 1K bytes (for 4byte
1481	pointers and size_t.)
1482	*/
1483
1484	/*
1485	Bins
1486
1487	An array of bin headers for free chunks. Each bin is doubly
1488	linked. The bins are approximately proportionally (log) spaced.
1489	There are a lot of these bins (128). This may look excessive, but
1490	works very well in practice. Most bins hold sizes that are
1491	unusual as malloc request sizes, but are more usual for fragments
1492	and consolidated sets of chunks, which is what these bins hold, so
1493	they can be found quickly. All procedures maintain the invariant
1494	that no consolidated chunk physically borders another one, so each
1495	chunk in a list is known to be preceded and followed by either
1496	inuse chunks or the ends of memory.
1497
1498	Chunks in bins are kept in size order, with ties going to the
1499	approximately least recently used chunk. Ordering isn't needed
1500	for the small bins, which all contain the same-sized chunks, but
1501	facilitates best-fit allocation for larger chunks. These lists
1502	are just sequential. Keeping them in order almost never requires
1503	enough traversal to warrant using fancier ordered data
1504	structures.
1505
1506	Chunks of the same size are linked with the most
1507	recently freed at the front, and allocations are taken from the
1508	back. This results in LRU (FIFO) allocation order, which tends
1509	to give each chunk an equal opportunity to be consolidated with
1510	adjacent freed chunks, resulting in larger free chunks and less
1511	fragmentation.
1512
1513	To simplify use in double-linked lists, each bin header acts
1514	as a malloc_chunk. This avoids special-casing for headers.
1515	But to conserve space and improve locality, we allocate
1516	only the fd/bk pointers of bins, and then use repositioning tricks
1517	to treat these as the fields of a malloc_chunk.*
1518	*/
1519
1520	typedef struct malloc_chunk *mbinptr;
1521
1522	/ addressing -- note that bin_at(0) does not exist /
1523	#define bin_at(m, i) \
1524	(mbinptr) (((char ) &((m)->bins[((i) - 1) 2])) \
1525	- offsetof (struct malloc_chunk, fd))
1526
1527	/ analog of ++bin /
1528	#define next_bin(b) ((mbinptr) ((char *) (b) + (sizeof (mchunkptr) << 1)))
1529
1530	/ Reminders about list directionality within bins /
1531	#define first(b) ((b)->fd)
1532	#define last(b) ((b)->bk)
1533
1534	/*
1535	Indexing
1536
1537	Bins for sizes < 512 bytes contain chunks of all the same size, spaced
1538	8 bytes apart. Larger bins are approximately logarithmically spaced:
1539
1540	64 bins of size 8
1541	32 bins of size 64
1542	16 bins of size 512
1543	8 bins of size 4096
1544	4 bins of size 32768
1545	2 bins of size 262144
1546	1 bin of size what's left
1547
1548	There is actually a little bit of slop in the numbers in bin_index
1549	for the sake of speed. This makes no difference elsewhere.
1550
1551	The bins top out around 1MB because we expect to service large
1552	requests via mmap.
1553
1554	Bin 0 does not exist. Bin 1 is the unordered list; if that would be
1555	a valid chunk size the small bins are bumped up one.
1556	*/
1557
1558	#define NBINS 128
1559	#define NSMALLBINS 64
1560	#define SMALLBIN_WIDTH MALLOC_ALIGNMENT
1561	#define SMALLBIN_CORRECTION (MALLOC_ALIGNMENT > CHUNK_HDR_SZ)
1562	#define MIN_LARGE_SIZE ((NSMALLBINS - SMALLBIN_CORRECTION) * SMALLBIN_WIDTH)
1563
1564	#define in_smallbin_range(sz) \
1565	((unsigned long) (sz) < (unsigned long) MIN_LARGE_SIZE)
1566
1567	#define smallbin_index(sz) \
1568	((SMALLBIN_WIDTH == 16 ? (((unsigned) (sz)) >> 4) : (((unsigned) (sz)) >> 3))\
1569	+ SMALLBIN_CORRECTION)
1570
1571	#define largebin_index_32(sz) \
1572	(((((unsigned long) (sz)) >> 6) <= 38) ? 56 + (((unsigned long) (sz)) >> 6) :\
1573	((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
1574	((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
1575	((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
1576	((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
1577	126)
1578
1579	#define largebin_index_32_big(sz) \
1580	(((((unsigned long) (sz)) >> 6) <= 45) ? 49 + (((unsigned long) (sz)) >> 6) :\
1581	((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
1582	((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
1583	((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
1584	((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
1585	126)
1586
1587	// XXX It remains to be seen whether it is good to keep the widths of
1588	// XXX the buckets the same or whether it should be scaled by a factor
1589	// XXX of two as well.
1590	#define largebin_index_64(sz) \
1591	(((((unsigned long) (sz)) >> 6) <= 48) ? 48 + (((unsigned long) (sz)) >> 6) :\
1592	((((unsigned long) (sz)) >> 9) <= 20) ? 91 + (((unsigned long) (sz)) >> 9) :\
1593	((((unsigned long) (sz)) >> 12) <= 10) ? 110 + (((unsigned long) (sz)) >> 12) :\
1594	((((unsigned long) (sz)) >> 15) <= 4) ? 119 + (((unsigned long) (sz)) >> 15) :\
1595	((((unsigned long) (sz)) >> 18) <= 2) ? 124 + (((unsigned long) (sz)) >> 18) :\
1596	126)
1597
1598	#define largebin_index(sz) \
1599	(SIZE_SZ == 8 ? largebin_index_64 (sz) \
1600	: MALLOC_ALIGNMENT == 16 ? largebin_index_32_big (sz) \
1601	: largebin_index_32 (sz))
1602
1603	#define bin_index(sz) \
1604	((in_smallbin_range (sz)) ? smallbin_index (sz) : largebin_index (sz))
1605
1606	/ Take a chunk off a bin list. /
1607	static void
1608	unlink_chunk (mstate av, mchunkptr p)
1609	{
1610	if (chunksize (p) != prev_size (next_chunk (p)))
1611	malloc_printerr (str: "corrupted size vs. prev_size");
1612
1613	mchunkptr fd = p->fd;
1614	mchunkptr bk = p->bk;
1615
1616	if (__builtin_expect (fd->bk != p \|\| bk->fd != p, `0`))
1617	malloc_printerr (str: "corrupted double-linked list");
1618
1619	fd->bk = bk;
1620	bk->fd = fd;
1621	if (!in_smallbin_range (chunksize_nomask (p)) && p->fd_nextsize != NULL)
1622	{
1623	if (p->fd_nextsize->bk_nextsize != p
1624	\|\| p->bk_nextsize->fd_nextsize != p)
1625	malloc_printerr (str: "corrupted double-linked list (not small)");
1626
1627	if (fd->fd_nextsize == NULL)
1628	{
1629	if (p->fd_nextsize == p)
1630	fd->fd_nextsize = fd->bk_nextsize = fd;
1631	else
1632	{
1633	fd->fd_nextsize = p->fd_nextsize;
1634	fd->bk_nextsize = p->bk_nextsize;
1635	p->fd_nextsize->bk_nextsize = fd;
1636	p->bk_nextsize->fd_nextsize = fd;
1637	}
1638	}
1639	else
1640	{
1641	p->fd_nextsize->bk_nextsize = p->bk_nextsize;
1642	p->bk_nextsize->fd_nextsize = p->fd_nextsize;
1643	}
1644	}
1645	}
1646
1647	/*
1648	Unsorted chunks
1649
1650	All remainders from chunk splits, as well as all returned chunks,
1651	are first placed in the "unsorted" bin. They are then placed
1652	in regular bins after malloc gives them ONE chance to be used before
1653	binning. So, basically, the unsorted_chunks list acts as a queue,
1654	with chunks being placed on it in free (and malloc_consolidate),
1655	and taken off (to be either used or placed in bins) in malloc.
1656
1657	The NON_MAIN_ARENA flag is never set for unsorted chunks, so it
1658	does not have to be taken into account in size comparisons.
1659	*/
1660
1661	/ The otherwise unindexable 1-bin is used to hold unsorted chunks. /
1662	#define unsorted_chunks(M) (bin_at (M, 1))
1663
1664	/*
1665	Top
1666
1667	The top-most available chunk (i.e., the one bordering the end of
1668	available memory) is treated specially. It is never included in
1669	any bin, is used only if no other chunk is available, and is
1670	released back to the system if it is very large (see
1671	M_TRIM_THRESHOLD). Because top initially
1672	points to its own bin with initial zero size, thus forcing
1673	extension on the first malloc request, we avoid having any special
1674	code in malloc to check whether it even exists yet. But we still
1675	need to do so when getting memory from system, so we make
1676	initial_top treat the bin as a legal but unusable chunk during the
1677	interval between initialization and the first call to
1678	sysmalloc. (This is somewhat delicate, since it relies on
1679	the 2 preceding words to be zero during this interval as well.)
1680	*/
1681
1682	/ Conveniently, the unsorted bin can be used as dummy top on first call /
1683	#define initial_top(M) (unsorted_chunks (M))
1684
1685	/*
1686	Binmap
1687
1688	To help compensate for the large number of bins, a one-level index
1689	structure is used for bin-by-bin searching. `binmap' is a
1690	bitvector recording whether bins are definitely empty so they can
1691	be skipped over during during traversals. The bits are NOT always
1692	cleared as soon as bins are empty, but instead only
1693	when they are noticed to be empty during traversal in malloc.
1694	*/
1695
1696	/ Conservatively use 32 bits per map word, even if on 64bit system /
1697	#define BINMAPSHIFT 5
1698	#define BITSPERMAP (1U << BINMAPSHIFT)
1699	#define BINMAPSIZE (NBINS / BITSPERMAP)
1700
1701	#define idx2block(i) ((i) >> BINMAPSHIFT)
1702	#define idx2bit(i) ((1U << ((i) & ((1U << BINMAPSHIFT) - 1))))
1703
1704	#define mark_bin(m, i) ((m)->binmap[idx2block (i)] \|= idx2bit (i))
1705	#define unmark_bin(m, i) ((m)->binmap[idx2block (i)] &= ~(idx2bit (i)))
1706	#define get_binmap(m, i) ((m)->binmap[idx2block (i)] & idx2bit (i))
1707
1708	/*
1709	Fastbins
1710
1711	An array of lists holding recently freed small chunks. Fastbins
1712	are not doubly linked. It is faster to single-link them, and
1713	since chunks are never removed from the middles of these lists,
1714	double linking is not necessary. Also, unlike regular bins, they
1715	are not even processed in FIFO order (they use faster LIFO) since
1716	ordering doesn't much matter in the transient contexts in which
1717	fastbins are normally used.
1718
1719	Chunks in fastbins keep their inuse bit set, so they cannot
1720	be consolidated with other free chunks. malloc_consolidate
1721	releases all chunks in fastbins and consolidates them with
1722	other free chunks.
1723	*/
1724
1725	typedef struct malloc_chunk *mfastbinptr;
1726	#define fastbin(ar_ptr, idx) ((ar_ptr)->fastbinsY[idx])
1727
1728	/ offset 2 to use otherwise unindexable first 2 bins /
1729	#define fastbin_index(sz) \
1730	((((unsigned int) (sz)) >> (SIZE_SZ == 8 ? 4 : 3)) - 2)
1731
1732
1733	/ The maximum fastbin request size we support /
1734	#define MAX_FAST_SIZE (80 * SIZE_SZ / 4)
1735
1736	#define NFASTBINS (fastbin_index (request2size (MAX_FAST_SIZE)) + 1)
1737
1738	/*
1739	FASTBIN_CONSOLIDATION_THRESHOLD is the size of a chunk in free()
1740	that triggers automatic consolidation of possibly-surrounding
1741	fastbin chunks. This is a heuristic, so the exact value should not
1742	matter too much. It is defined at half the default trim threshold as a
1743	compromise heuristic to only attempt consolidation if it is likely
1744	to lead to trimming. However, it is not dynamically tunable, since
1745	consolidation reduces fragmentation surrounding large chunks even
1746	if trimming is not used.
1747	*/
1748
1749	#define FASTBIN_CONSOLIDATION_THRESHOLD (65536UL)
1750
1751	/*
1752	NONCONTIGUOUS_BIT indicates that MORECORE does not return contiguous
1753	regions. Otherwise, contiguity is exploited in merging together,
1754	when possible, results from consecutive MORECORE calls.
1755
1756	The initial value comes from MORECORE_CONTIGUOUS, but is
1757	changed dynamically if mmap is ever used as an sbrk substitute.
1758	*/
1759
1760	#define NONCONTIGUOUS_BIT (2U)
1761
1762	#define contiguous(M) (((M)->flags & NONCONTIGUOUS_BIT) == 0)
1763	#define noncontiguous(M) (((M)->flags & NONCONTIGUOUS_BIT) != 0)
1764	#define set_noncontiguous(M) ((M)->flags \|= NONCONTIGUOUS_BIT)
1765	#define set_contiguous(M) ((M)->flags &= ~NONCONTIGUOUS_BIT)
1766
1767	/ Maximum size of memory handled in fastbins. /
1768	static uint8_t global_max_fast;
1769
1770	/*
1771	Set value of max_fast.
1772	Use impossibly small value if 0.
1773	Precondition: there are no existing fastbin chunks in the main arena.
1774	Since do_check_malloc_state () checks this, we call malloc_consolidate ()
1775	before changing max_fast. Note other arenas will leak their fast bin
1776	entries if max_fast is reduced.
1777	*/
1778
1779	#define set_max_fast(s) \
1780	global_max_fast = (((size_t) (s) <= MALLOC_ALIGN_MASK - SIZE_SZ) \
1781	? MIN_CHUNK_SIZE / 2 : ((s + SIZE_SZ) & ~MALLOC_ALIGN_MASK))
1782
1783	static inline INTERNAL_SIZE_T
1784	get_max_fast (void)
1785	{
1786	/ Tell the GCC optimizers that global_max_fast is never larger*
1787	than MAX_FAST_SIZE. This avoids out-of-bounds array accesses in
1788	_int_malloc after constant propagation of the size parameter.
1789	(The code never executes because malloc preserves the
1790	global_max_fast invariant, but the optimizers may not recognize
1791	this.) /*
1792	if (global_max_fast > MAX_FAST_SIZE)
1793	__builtin_unreachable ();
1794	return global_max_fast;
1795	}
1796
1797	/*
1798	----------- Internal state representation and initialization -----------
1799	*/
1800
1801	/*
1802	have_fastchunks indicates that there are probably some fastbin chunks.
1803	It is set true on entering a chunk into any fastbin, and cleared early in
1804	malloc_consolidate. The value is approximate since it may be set when there
1805	are no fastbin chunks, or it may be clear even if there are fastbin chunks
1806	available. Given it's sole purpose is to reduce number of redundant calls to
1807	malloc_consolidate, it does not affect correctness. As a result we can safely
1808	use relaxed atomic accesses.
1809	*/
1810
1811
1812	struct malloc_state
1813	{
1814	/ Serialize access. /
1815	__libc_lock_define (, mutex);
1816
1817	/ Flags (formerly in max_fast). /
1818	int flags;
1819
1820	/ Set if the fastbin chunks contain recently inserted free blocks. /
1821	/ Note this is a bool but not all targets support atomics on booleans. /
1822	int have_fastchunks;
1823
1824	/ Fastbins /
1825	mfastbinptr fastbinsY[NFASTBINS];
1826
1827	/ Base of the topmost chunk -- not otherwise kept in a bin /
1828	mchunkptr top;
1829
1830	/ The remainder from the most recent split of a small request /
1831	mchunkptr last_remainder;
1832
1833	/ Normal bins packed as described above /
1834	mchunkptr bins[NBINS * `2` - `2`];
1835
1836	/ Bitmap of bins /
1837	unsigned int binmap[BINMAPSIZE];
1838
1839	/ Linked list /
1840	struct malloc_state *next;
1841
1842	/ Linked list for free arenas. Access to this field is serialized*
1843	by free_list_lock in arena.c. /*
1844	struct malloc_state *next_free;
1845
1846	/ Number of threads attached to this arena. 0 if the arena is on*
1847	the free list. Access to this field is serialized by
1848	free_list_lock in arena.c. /*
1849	INTERNAL_SIZE_T attached_threads;
1850
1851	/ Memory allocated from the system in this arena. /
1852	INTERNAL_SIZE_T system_mem;
1853	INTERNAL_SIZE_T max_system_mem;
1854	};
1855
1856	struct malloc_par
1857	{
1858	/ Tunable parameters /
1859	unsigned long trim_threshold;
1860	INTERNAL_SIZE_T top_pad;
1861	INTERNAL_SIZE_T mmap_threshold;
1862	INTERNAL_SIZE_T arena_test;
1863	INTERNAL_SIZE_T arena_max;
1864
1865	/ Transparent Large Page support. /
1866	INTERNAL_SIZE_T thp_pagesize;
1867	/ A value different than 0 means to align mmap allocation to hp_pagesize*
1868	add hp_flags on flags. /*
1869	INTERNAL_SIZE_T hp_pagesize;
1870	int hp_flags;
1871
1872	/ Memory map support /
1873	int n_mmaps;
1874	int n_mmaps_max;
1875	int max_n_mmaps;
1876	/ the mmap_threshold is dynamic, until the user sets*
1877	it manually, at which point we need to disable any
1878	dynamic behavior. /*
1879	int no_dyn_threshold;
1880
1881	/ Statistics /
1882	INTERNAL_SIZE_T mmapped_mem;
1883	INTERNAL_SIZE_T max_mmapped_mem;
1884
1885	/ First address handed out by MORECORE/sbrk. /
1886	char *sbrk_base;
1887
1888	#if USE_TCACHE
1889	/ Maximum number of buckets to use. /
1890	size_t tcache_bins;
1891	size_t tcache_max_bytes;
1892	/ Maximum number of chunks in each bucket. /
1893	size_t tcache_count;
1894	/ Maximum number of chunks to remove from the unsorted list, which*
1895	aren't used to prefill the cache. /*
1896	size_t tcache_unsorted_limit;
1897	#endif
1898	};
1899
1900	/ There are several instances of this struct ("arenas") in this*
1901	malloc. If you are adapting this malloc in a way that does NOT use
1902	a static or mmapped malloc_state, you MUST explicitly zero-fill it
1903	before using. This malloc relies on the property that malloc_state
1904	is initialized to all zeroes (as is true of C statics). /*
1905
1906	static struct malloc_state main_arena =
1907	{
1908	.mutex = _LIBC_LOCK_INITIALIZER,
1909	.next = &main_arena,
1910	.attached_threads = `1`
1911	};
1912
1913	/ There is only one instance of the malloc parameters. /
1914
1915	static struct malloc_par mp_ =
1916	{
1917	.top_pad = DEFAULT_TOP_PAD,
1918	.n_mmaps_max = DEFAULT_MMAP_MAX,
1919	.mmap_threshold = DEFAULT_MMAP_THRESHOLD,
1920	.trim_threshold = DEFAULT_TRIM_THRESHOLD,
1921	#define NARENAS_FROM_NCORES(n) ((n) * (sizeof (long) == 4 ? 2 : 8))
1922	.arena_test = NARENAS_FROM_NCORES (`1`)
1923	#if USE_TCACHE
1924	,
1925	.tcache_count = TCACHE_FILL_COUNT,
1926	.tcache_bins = TCACHE_MAX_BINS,
1927	.tcache_max_bytes = tidx2usize (TCACHE_MAX_BINS-`1`),
1928	.tcache_unsorted_limit = `0` / No limit. /
1929	#endif
1930	};
1931
1932	/*
1933	Initialize a malloc_state struct.
1934
1935	This is called from ptmalloc_init () or from _int_new_arena ()
1936	when creating a new arena.
1937	*/
1938
1939	static void
1940	malloc_init_state (mstate av)
1941	{
1942	int i;
1943	mbinptr bin;
1944
1945	/ Establish circular links for normal bins /
1946	for (i = `1`; i < NBINS; ++i)
1947	{
1948	bin = bin_at (av, i);
1949	bin->fd = bin->bk = bin;
1950	}
1951
1952	#if MORECORE_CONTIGUOUS
1953	if (av != &main_arena)
1954	#endif
1955	set_noncontiguous (av);
1956	if (av == &main_arena)
1957	set_max_fast (DEFAULT_MXFAST);
1958	atomic_store_relaxed (&av->have_fastchunks, false);
1959
1960	av->top = initial_top (av);
1961	}
1962
1963	/*
1964	Other internal utilities operating on mstates
1965	*/
1966
1967	static void *sysmalloc (INTERNAL_SIZE_T, mstate);
1968	static int systrim (size_t, mstate);
1969	static void malloc_consolidate (mstate);
1970
1971
1972	/ -------------- Early definitions for debugging hooks ---------------- /
1973
1974	/ This function is called from the arena shutdown hook, to free the*
1975	thread cache (if it exists). /*
1976	static void tcache_thread_shutdown (void);
1977
1978	/ ------------------ Testing support ----------------------------------/
1979
1980	static int perturb_byte;
1981
1982	static void
1983	alloc_perturb (char *p, size_t n)
1984	{
1985	if (__glibc_unlikely (perturb_byte))
1986	memset (s: p, c: perturb_byte ^ `0xff`, n: n);
1987	}
1988
1989	static void
1990	free_perturb (char *p, size_t n)
1991	{
1992	if (__glibc_unlikely (perturb_byte))
1993	memset (s: p, c: perturb_byte, n: n);
1994	}
1995
1996
1997
1998	#include <stap-probe.h>
1999
2000	/ ----------- Routines dealing with transparent huge pages ----------- /
2001
2002	static inline void
2003	madvise_thp (void *p, INTERNAL_SIZE_T size)
2004	{
2005	#ifdef MADV_HUGEPAGE
2006	/ Do not consider areas smaller than a huge page or if the tunable is*
2007	not active. /*
2008	if (mp_.thp_pagesize == `0` \|\| size < mp_.thp_pagesize)
2009	return;
2010
2011	/ Linux requires the input address to be page-aligned, and unaligned*
2012	inputs happens only for initial data segment. /*
2013	if (__glibc_unlikely (!PTR_IS_ALIGNED (p, GLRO (dl_pagesize))))
2014	{
2015	void *q = PTR_ALIGN_DOWN (p, GLRO (dl_pagesize));
2016	size += PTR_DIFF (p, q);
2017	p = q;
2018	}
2019
2020	__madvise (addr: p, len: size, MADV_HUGEPAGE);
2021	#endif
2022	}
2023
2024	/ ------------------- Support for multiple arenas -------------------- /
2025	#include "arena.c"
2026
2027	/*
2028	Debugging support
2029
2030	These routines make a number of assertions about the states
2031	of data structures that should be true at all times. If any
2032	are not true, it's very likely that a user program has somehow
2033	trashed memory. (It's also possible that there is a coding error
2034	in malloc. In which case, please report it!)
2035	*/
2036
2037	#if !MALLOC_DEBUG
2038
2039	# define check_chunk(A, P)
2040	# define check_free_chunk(A, P)
2041	# define check_inuse_chunk(A, P)
2042	# define check_remalloced_chunk(A, P, N)
2043	# define check_malloced_chunk(A, P, N)
2044	# define check_malloc_state(A)
2045
2046	#else
2047
2048	# define check_chunk(A, P) do_check_chunk (A, P)
2049	# define check_free_chunk(A, P) do_check_free_chunk (A, P)
2050	# define check_inuse_chunk(A, P) do_check_inuse_chunk (A, P)
2051	# define check_remalloced_chunk(A, P, N) do_check_remalloced_chunk (A, P, N)
2052	# define check_malloced_chunk(A, P, N) do_check_malloced_chunk (A, P, N)
2053	# define check_malloc_state(A) do_check_malloc_state (A)
2054
2055	/*
2056	Properties of all chunks
2057	*/
2058
2059	static void
2060	do_check_chunk (mstate av, mchunkptr p)
2061	{
2062	unsigned long sz = chunksize (p);
2063	/ min and max possible addresses assuming contiguous allocation /
2064	char max_address = (char* *) (av->top) + chunksize (av->top);
2065	char *min_address = max_address - av->system_mem;
2066
2067	if (!chunk_is_mmapped (p))
2068	{
2069	/ Has legal address ... /
2070	if (p != av->top)
2071	{
2072	if (contiguous (av))
2073	{
2074	assert (((char *) p) >= min_address);
2075	assert (((char ) p + sz) <= ((char* *) (av->top)));
2076	}
2077	}
2078	else
2079	{
2080	/ top size is always at least MINSIZE /
2081	assert ((unsigned long) (sz) >= MINSIZE);
2082	/ top predecessor always marked inuse /
2083	assert (prev_inuse (p));
2084	}
2085	}
2086	else
2087	{
2088	/ address is outside main heap /
2089	if (contiguous (av) && av->top != initial_top (av))
2090	{
2091	assert (((char ) p) < min_address \|\| ((char* *) p) >= max_address);
2092	}
2093	/ chunk is page-aligned /
2094	assert (((prev_size (p) + sz) & (GLRO (dl_pagesize) - `1`)) == `0`);
2095	/ mem is aligned /
2096	assert (aligned_OK (chunk2mem (p)));
2097	}
2098	}
2099
2100	/*
2101	Properties of free chunks
2102	*/
2103
2104	static void
2105	do_check_free_chunk (mstate av, mchunkptr p)
2106	{
2107	INTERNAL_SIZE_T sz = chunksize_nomask (p) & ~(PREV_INUSE \| NON_MAIN_ARENA);
2108	mchunkptr next = chunk_at_offset (p, sz);
2109
2110	do_check_chunk (av, p);
2111
2112	/ Chunk must claim to be free ... /
2113	assert (!inuse (p));
2114	assert (!chunk_is_mmapped (p));
2115
2116	/ Unless a special marker, must have OK fields /
2117	if ((unsigned long) (sz) >= MINSIZE)
2118	{
2119	assert ((sz & MALLOC_ALIGN_MASK) == `0`);
2120	assert (aligned_OK (chunk2mem (p)));
2121	/ ... matching footer field /
2122	assert (prev_size (next_chunk (p)) == sz);
2123	/ ... and is fully consolidated /
2124	assert (prev_inuse (p));
2125	assert (next == av->top \|\| inuse (next));
2126
2127	/ ... and has minimally sane links /
2128	assert (p->fd->bk == p);
2129	assert (p->bk->fd == p);
2130	}
2131	else / markers are always of size SIZE_SZ /
2132	assert (sz == SIZE_SZ);
2133	}
2134
2135	/*
2136	Properties of inuse chunks
2137	*/
2138
2139	static void
2140	do_check_inuse_chunk (mstate av, mchunkptr p)
2141	{
2142	mchunkptr next;
2143
2144	do_check_chunk (av, p);
2145
2146	if (chunk_is_mmapped (p))
2147	return; / mmapped chunks have no next/prev /
2148
2149	/ Check whether it claims to be in use ... /
2150	assert (inuse (p));
2151
2152	next = next_chunk (p);
2153
2154	/ ... and is surrounded by OK chunks.*
2155	Since more things can be checked with free chunks than inuse ones,
2156	if an inuse chunk borders them and debug is on, it's worth doing them.
2157	*/
2158	if (!prev_inuse (p))
2159	{
2160	/ Note that we cannot even look at prev unless it is not inuse /
2161	mchunkptr prv = prev_chunk (p);
2162	assert (next_chunk (prv) == p);
2163	do_check_free_chunk (av, prv);
2164	}
2165
2166	if (next == av->top)
2167	{
2168	assert (prev_inuse (next));
2169	assert (chunksize (next) >= MINSIZE);
2170	}
2171	else if (!inuse (next))
2172	do_check_free_chunk (av, next);
2173	}
2174
2175	/*
2176	Properties of chunks recycled from fastbins
2177	*/
2178
2179	static void
2180	do_check_remalloced_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T s)
2181	{
2182	INTERNAL_SIZE_T sz = chunksize_nomask (p) & ~(PREV_INUSE \| NON_MAIN_ARENA);
2183
2184	if (!chunk_is_mmapped (p))
2185	{
2186	assert (av == arena_for_chunk (p));
2187	if (chunk_main_arena (p))
2188	assert (av == &main_arena);
2189	else
2190	assert (av != &main_arena);
2191	}
2192
2193	do_check_inuse_chunk (av, p);
2194
2195	/ Legal size ... /
2196	assert ((sz & MALLOC_ALIGN_MASK) == `0`);
2197	assert ((unsigned long) (sz) >= MINSIZE);
2198	/ ... and alignment /
2199	assert (aligned_OK (chunk2mem (p)));
2200	/ chunk is less than MINSIZE more than request /
2201	assert ((long) (sz) - (long) (s) >= `0`);
2202	assert ((long) (sz) - (long) (s + MINSIZE) < `0`);
2203	}
2204
2205	/*
2206	Properties of nonrecycled chunks at the point they are malloced
2207	*/
2208
2209	static void
2210	do_check_malloced_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T s)
2211	{
2212	/ same as recycled case ... /
2213	do_check_remalloced_chunk (av, p, s);
2214
2215	/*
2216	... plus, must obey implementation invariant that prev_inuse is
2217	always true of any allocated chunk; i.e., that each allocated
2218	chunk borders either a previously allocated and still in-use
2219	chunk, or the base of its memory arena. This is ensured
2220	by making all allocations from the `lowest' part of any found
2221	chunk. This does not necessarily hold however for chunks
2222	recycled via fastbins.
2223	*/
2224
2225	assert (prev_inuse (p));
2226	}
2227
2228
2229	/*
2230	Properties of malloc_state.
2231
2232	This may be useful for debugging malloc, as well as detecting user
2233	programmer errors that somehow write into malloc_state.
2234
2235	If you are extending or experimenting with this malloc, you can
2236	probably figure out how to hack this routine to print out or
2237	display chunk addresses, sizes, bins, and other instrumentation.
2238	*/
2239
2240	static void
2241	do_check_malloc_state (mstate av)
2242	{
2243	int i;
2244	mchunkptr p;
2245	mchunkptr q;
2246	mbinptr b;
2247	unsigned int idx;
2248	INTERNAL_SIZE_T size;
2249	unsigned long total = `0`;
2250	int max_fast_bin;
2251
2252	/ internal size_t must be no wider than pointer type /
2253	assert (sizeof (INTERNAL_SIZE_T) <= sizeof (char *));
2254
2255	/ alignment is a power of 2 /
2256	assert ((MALLOC_ALIGNMENT & (MALLOC_ALIGNMENT - `1`)) == `0`);
2257
2258	/ Check the arena is initialized. /
2259	assert (av->top != `0`);
2260
2261	/ No memory has been allocated yet, so doing more tests is not possible. /
2262	if (av->top == initial_top (av))
2263	return;
2264
2265	/ pagesize is a power of 2 /
2266	assert (powerof2(GLRO (dl_pagesize)));
2267
2268	/ A contiguous main_arena is consistent with sbrk_base. /
2269	if (av == &main_arena && contiguous (av))
2270	assert ((char *) mp_.sbrk_base + av->system_mem ==
2271	(char *) av->top + chunksize (av->top));
2272
2273	/ properties of fastbins /
2274
2275	/ max_fast is in allowed range /
2276	assert ((get_max_fast () & ~`1`) <= request2size (MAX_FAST_SIZE));
2277
2278	max_fast_bin = fastbin_index (get_max_fast ());
2279
2280	for (i = `0`; i < NFASTBINS; ++i)
2281	{
2282	p = fastbin (av, i);
2283
2284	/ The following test can only be performed for the main arena.*
2285	While mallopt calls malloc_consolidate to get rid of all fast
2286	bins (especially those larger than the new maximum) this does
2287	only happen for the main arena. Trying to do this for any
2288	other arena would mean those arenas have to be locked and
2289	malloc_consolidate be called for them. This is excessive. And
2290	even if this is acceptable to somebody it still cannot solve
2291	the problem completely since if the arena is locked a
2292	concurrent malloc call might create a new arena which then
2293	could use the newly invalid fast bins. /*
2294
2295	/ all bins past max_fast are empty /
2296	if (av == &main_arena && i > max_fast_bin)
2297	assert (p == `0`);
2298
2299	while (p != `0`)
2300	{
2301	if (__glibc_unlikely (misaligned_chunk (p)))
2302	malloc_printerr ("do_check_malloc_state(): "
2303	"unaligned fastbin chunk detected");
2304	/ each chunk claims to be inuse /
2305	do_check_inuse_chunk (av, p);
2306	total += chunksize (p);
2307	/ chunk belongs in this bin /
2308	assert (fastbin_index (chunksize (p)) == i);
2309	p = REVEAL_PTR (p->fd);
2310	}
2311	}
2312
2313	/ check normal bins /
2314	for (i = `1`; i < NBINS; ++i)
2315	{
2316	b = bin_at (av, i);
2317
2318	/ binmap is accurate (except for bin 1 == unsorted_chunks) /
2319	if (i >= `2`)
2320	{
2321	unsigned int binbit = get_binmap (av, i);
2322	int empty = last (b) == b;
2323	if (!binbit)
2324	assert (empty);
2325	else if (!empty)
2326	assert (binbit);
2327	}
2328
2329	for (p = last (b); p != b; p = p->bk)
2330	{
2331	/ each chunk claims to be free /
2332	do_check_free_chunk (av, p);
2333	size = chunksize (p);
2334	total += size;
2335	if (i >= `2`)
2336	{
2337	/ chunk belongs in bin /
2338	idx = bin_index (size);
2339	assert (idx == i);
2340	/ lists are sorted /
2341	assert (p->bk == b \|\|
2342	(unsigned long) chunksize (p->bk) >= (unsigned long) chunksize (p));
2343
2344	if (!in_smallbin_range (size))
2345	{
2346	if (p->fd_nextsize != NULL)
2347	{
2348	if (p->fd_nextsize == p)
2349	assert (p->bk_nextsize == p);
2350	else
2351	{
2352	if (p->fd_nextsize == first (b))
2353	assert (chunksize (p) < chunksize (p->fd_nextsize));
2354	else
2355	assert (chunksize (p) > chunksize (p->fd_nextsize));
2356
2357	if (p == first (b))
2358	assert (chunksize (p) > chunksize (p->bk_nextsize));
2359	else
2360	assert (chunksize (p) < chunksize (p->bk_nextsize));
2361	}
2362	}
2363	else
2364	assert (p->bk_nextsize == NULL);
2365	}
2366	}
2367	else if (!in_smallbin_range (size))
2368	assert (p->fd_nextsize == NULL && p->bk_nextsize == NULL);
2369	/ chunk is followed by a legal chain of inuse chunks /
2370	for (q = next_chunk (p);
2371	(q != av->top && inuse (q) &&
2372	(unsigned long) (chunksize (q)) >= MINSIZE);
2373	q = next_chunk (q))
2374	do_check_inuse_chunk (av, q);
2375	}
2376	}
2377
2378	/ top chunk is OK /
2379	check_chunk (av, av->top);
2380	}
2381	#endif
2382
2383
2384	/ ----------------- Support for debugging hooks -------------------- /
2385	#if IS_IN (libc)
2386	#include "hooks.c"
2387	#endif
2388
2389
2390	/ ----------- Routines dealing with system allocation -------------- /
2391
2392	/*
2393	sysmalloc handles malloc cases requiring more memory from the system.
2394	On entry, it is assumed that av->top does not have enough
2395	space to service request for nb bytes, thus requiring that av->top
2396	be extended or replaced.
2397	*/
2398
2399	static void *
2400	sysmalloc_mmap (INTERNAL_SIZE_T nb, size_t pagesize, int extra_flags, mstate av)
2401	{
2402	long int size;
2403
2404	/*
2405	Round up size to nearest page. For mmapped chunks, the overhead is one
2406	SIZE_SZ unit larger than for normal chunks, because there is no
2407	following chunk whose prev_size field could be used.
2408
2409	See the front_misalign handling below, for glibc there is no need for
2410	further alignments unless we have have high alignment.
2411	*/
2412	if (MALLOC_ALIGNMENT == CHUNK_HDR_SZ)
2413	size = ALIGN_UP (nb + SIZE_SZ, pagesize);
2414	else
2415	size = ALIGN_UP (nb + SIZE_SZ + MALLOC_ALIGN_MASK, pagesize);
2416
2417	/ Don't try if size wraps around 0. /
2418	if ((unsigned long) (size) <= (unsigned long) (nb))
2419	return MAP_FAILED;
2420
2421	char mm = (char* *) MMAP (`0`, size,
2422	mtag_mmap_flags \| PROT_READ \| PROT_WRITE,
2423	extra_flags);
2424	if (mm == MAP_FAILED)
2425	return mm;
2426
2427	#ifdef MAP_HUGETLB
2428	if (!(extra_flags & MAP_HUGETLB))
2429	madvise_thp (p: mm, size);
2430	#endif
2431
2432	__set_vma_name (start: mm, len: size, name: " glibc: malloc");
2433
2434	/*
2435	The offset to the start of the mmapped region is stored in the prev_size
2436	field of the chunk. This allows us to adjust returned start address to
2437	meet alignment requirements here and in memalign(), and still be able to
2438	compute proper address argument for later munmap in free() and realloc().
2439	*/
2440
2441	INTERNAL_SIZE_T front_misalign; / unusable bytes at front of new space /
2442
2443	if (MALLOC_ALIGNMENT == CHUNK_HDR_SZ)
2444	{
2445	/ For glibc, chunk2mem increases the address by CHUNK_HDR_SZ and*
2446	MALLOC_ALIGN_MASK is CHUNK_HDR_SZ-1. Each mmap'ed area is page
2447	aligned and therefore definitely MALLOC_ALIGN_MASK-aligned. /*
2448	assert (((INTERNAL_SIZE_T) chunk2mem (mm) & MALLOC_ALIGN_MASK) == `0`);
2449	front_misalign = `0`;
2450	}
2451	else
2452	front_misalign = (INTERNAL_SIZE_T) chunk2mem (mm) & MALLOC_ALIGN_MASK;
2453
2454	mchunkptr p; / the allocated/returned chunk /
2455
2456	if (front_misalign > `0`)
2457	{
2458	ptrdiff_t correction = MALLOC_ALIGNMENT - front_misalign;
2459	p = (mchunkptr) (mm + correction);
2460	set_prev_size (p, correction);
2461	set_head (p, (size - correction) \| IS_MMAPPED);
2462	}
2463	else
2464	{
2465	p = (mchunkptr) mm;
2466	set_prev_size (p, `0`);
2467	set_head (p, size \| IS_MMAPPED);
2468	}
2469
2470	/ update statistics /
2471	int new = atomic_fetch_add_relaxed (&mp_.n_mmaps, `1`) + `1`;
2472	atomic_max (&mp_.max_n_mmaps, new);
2473
2474	unsigned long sum;
2475	sum = atomic_fetch_add_relaxed (&mp_.mmapped_mem, size) + size;
2476	atomic_max (&mp_.max_mmapped_mem, sum);
2477
2478	check_chunk (av, p);
2479
2480	return chunk2mem (p);
2481	}
2482
2483	/*
2484	Allocate memory using mmap() based on S and NB requested size, aligning to
2485	PAGESIZE if required. The EXTRA_FLAGS is used on mmap() call. If the call
2486	succeeds S is updated with the allocated size. This is used as a fallback
2487	if MORECORE fails.
2488	*/
2489	static void *
2490	sysmalloc_mmap_fallback (long int *s, INTERNAL_SIZE_T nb,
2491	INTERNAL_SIZE_T old_size, size_t minsize,
2492	size_t pagesize, int extra_flags, mstate av)
2493	{
2494	long int size = *s;
2495
2496	/ Cannot merge with old top, so add its size back in /
2497	if (contiguous (av))
2498	size = ALIGN_UP (size + old_size, pagesize);
2499
2500	/ If we are relying on mmap as backup, then use larger units /
2501	if ((unsigned long) (size) < minsize)
2502	size = minsize;
2503
2504	/ Don't try if size wraps around 0 /
2505	if ((unsigned long) (size) <= (unsigned long) (nb))
2506	return MORECORE_FAILURE;
2507
2508	char mbrk = (char* *) (MMAP (`0`, size,
2509	mtag_mmap_flags \| PROT_READ \| PROT_WRITE,
2510	extra_flags));
2511	if (mbrk == MAP_FAILED)
2512	return MAP_FAILED;
2513
2514	#ifdef MAP_HUGETLB
2515	if (!(extra_flags & MAP_HUGETLB))
2516	madvise_thp (p: mbrk, size);
2517	#endif
2518
2519	__set_vma_name (start: mbrk, len: size, name: " glibc: malloc");
2520
2521	/ Record that we no longer have a contiguous sbrk region. After the first*
2522	time mmap is used as backup, we do not ever rely on contiguous space
2523	since this could incorrectly bridge regions. /*
2524	set_noncontiguous (av);
2525
2526	*s = size;
2527	return mbrk;
2528	}
2529
2530	static void *
2531	sysmalloc (INTERNAL_SIZE_T nb, mstate av)
2532	{
2533	mchunkptr old_top; / incoming value of av->top /
2534	INTERNAL_SIZE_T old_size; / its size /
2535	char old_end; /* its end address /
2536
2537	long size; / arg to first MORECORE or mmap call /
2538	char brk; /* return value from MORECORE /
2539
2540	long correction; / arg to 2nd MORECORE call /
2541	char snd_brk; /* 2nd return val /
2542
2543	INTERNAL_SIZE_T front_misalign; / unusable bytes at front of new space /
2544	INTERNAL_SIZE_T end_misalign; / partial page left at end of new space /
2545	char aligned_brk; /* aligned offset into brk /
2546
2547	mchunkptr p; / the allocated/returned chunk /
2548	mchunkptr remainder; / remainder from allocation /
2549	unsigned long remainder_size; / its size /
2550
2551
2552	size_t pagesize = GLRO (dl_pagesize);
2553	bool tried_mmap = false;
2554
2555
2556	/*
2557	If have mmap, and the request size meets the mmap threshold, and
2558	the system supports mmap, and there are few enough currently
2559	allocated mmapped regions, try to directly map this request
2560	rather than expanding top.
2561	*/
2562
2563	if (av == NULL
2564	\|\| ((unsigned long) (nb) >= (unsigned long) (mp_.mmap_threshold)
2565	&& (mp_.n_mmaps < mp_.n_mmaps_max)))
2566	{
2567	char *mm;
2568	if (mp_.hp_pagesize > `0` && nb >= mp_.hp_pagesize)
2569	{
2570	/ There is no need to issue the THP madvise call if Huge Pages are*
2571	used directly. /*
2572	mm = sysmalloc_mmap (nb, pagesize: mp_.hp_pagesize, extra_flags: mp_.hp_flags, av);
2573	if (mm != MAP_FAILED)
2574	return mm;
2575	}
2576	mm = sysmalloc_mmap (nb, pagesize, extra_flags: `0`, av);
2577	if (mm != MAP_FAILED)
2578	return mm;
2579	tried_mmap = true;
2580	}
2581
2582	/ There are no usable arenas and mmap also failed. /
2583	if (av == NULL)
2584	return `0`;
2585
2586	/ Record incoming configuration of top /
2587
2588	old_top = av->top;
2589	old_size = chunksize (old_top);
2590	old_end = (char *) (chunk_at_offset (old_top, old_size));
2591
2592	brk = snd_brk = (char *) (MORECORE_FAILURE);
2593
2594	/*
2595	If not the first time through, we require old_size to be
2596	at least MINSIZE and to have prev_inuse set.
2597	*/
2598
2599	assert ((old_top == initial_top (av) && old_size == `0`) \|\|
2600	((unsigned long) (old_size) >= MINSIZE &&
2601	prev_inuse (old_top) &&
2602	((unsigned long) old_end & (pagesize - `1`)) == `0`));
2603
2604	/ Precondition: not enough current space to satisfy nb request /
2605	assert ((unsigned long) (old_size) < (unsigned long) (nb + MINSIZE));
2606
2607
2608	if (av != &main_arena)
2609	{
2610	heap_info old_heap, heap;
2611	size_t old_heap_size;
2612
2613	/ First try to extend the current heap. /
2614	old_heap = heap_for_ptr (ptr: old_top);
2615	old_heap_size = old_heap->size;
2616	if ((long) (MINSIZE + nb - old_size) > `0`
2617	&& grow_heap (h: old_heap, MINSIZE + nb - old_size) == `0`)
2618	{
2619	av->system_mem += old_heap->size - old_heap_size;
2620	set_head (old_top, (((char ) old_heap + old_heap->size) - (char* *) old_top)
2621	\| PREV_INUSE);
2622	}
2623	else if ((heap = new_heap (size: nb + (MINSIZE + sizeof (*heap)), top_pad: mp_.top_pad)))
2624	{
2625	/ Use a newly allocated heap. /
2626	heap->ar_ptr = av;
2627	heap->prev = old_heap;
2628	av->system_mem += heap->size;
2629	/ Set up the new top. /
2630	top (av) = chunk_at_offset (heap, sizeof (*heap));
2631	set_head (top (av), (heap->size - sizeof (*heap)) \| PREV_INUSE);
2632
2633	/ Setup fencepost and free the old top chunk with a multiple of*
2634	MALLOC_ALIGNMENT in size. /*
2635	/ The fencepost takes at least MINSIZE bytes, because it might*
2636	become the top chunk again later. Note that a footer is set
2637	up, too, although the chunk is marked in use. /*
2638	old_size = (old_size - MINSIZE) & ~MALLOC_ALIGN_MASK;
2639	set_head (chunk_at_offset (old_top, old_size + CHUNK_HDR_SZ),
2640	`0` \| PREV_INUSE);
2641	if (old_size >= MINSIZE)
2642	{
2643	set_head (chunk_at_offset (old_top, old_size),
2644	CHUNK_HDR_SZ \| PREV_INUSE);
2645	set_foot (chunk_at_offset (old_top, old_size), CHUNK_HDR_SZ);
2646	set_head (old_top, old_size \| PREV_INUSE \| NON_MAIN_ARENA);
2647	_int_free (av, old_top, `1`);
2648	}
2649	else
2650	{
2651	set_head (old_top, (old_size + CHUNK_HDR_SZ) \| PREV_INUSE);
2652	set_foot (old_top, (old_size + CHUNK_HDR_SZ));
2653	}
2654	}
2655	else if (!tried_mmap)
2656	{
2657	/ We can at least try to use to mmap memory. If new_heap fails*
2658	it is unlikely that trying to allocate huge pages will
2659	succeed. /*
2660	char *mm = sysmalloc_mmap (nb, pagesize, extra_flags: `0`, av);
2661	if (mm != MAP_FAILED)
2662	return mm;
2663	}
2664	}
2665	else / av == main_arena /
2666
2667
2668	{ / Request enough space for nb + pad + overhead /
2669	size = nb + mp_.top_pad + MINSIZE;
2670
2671	/*
2672	If contiguous, we can subtract out existing space that we hope to
2673	combine with new space. We add it back later only if
2674	we don't actually get contiguous space.
2675	*/
2676
2677	if (contiguous (av))
2678	size -= old_size;
2679
2680	/*
2681	Round to a multiple of page size or huge page size.
2682	If MORECORE is not contiguous, this ensures that we only call it
2683	with whole-page arguments. And if MORECORE is contiguous and
2684	this is not first time through, this preserves page-alignment of
2685	previous calls. Otherwise, we correct to page-align below.
2686	*/
2687
2688	#ifdef MADV_HUGEPAGE
2689	/ Defined in brk.c. /
2690	extern void *__curbrk;
2691	if (__glibc_unlikely (mp_.thp_pagesize != `0`))
2692	{
2693	uintptr_t top = ALIGN_UP ((uintptr_t) __curbrk + size,
2694	mp_.thp_pagesize);
2695	size = top - (uintptr_t) __curbrk;
2696	}
2697	else
2698	#endif
2699	size = ALIGN_UP (size, GLRO(dl_pagesize));
2700
2701	/*
2702	Don't try to call MORECORE if argument is so big as to appear
2703	negative. Note that since mmap takes size_t arg, it may succeed
2704	below even if we cannot call MORECORE.
2705	*/
2706
2707	if (size > `0`)
2708	{
2709	brk = (char *) (MORECORE (increment: size));
2710	if (brk != (char *) (MORECORE_FAILURE))
2711	madvise_thp (p: brk, size);
2712	LIBC_PROBE (memory_sbrk_more, `2`, brk, size);
2713	}
2714
2715	if (brk == (char *) (MORECORE_FAILURE))
2716	{
2717	/*
2718	If have mmap, try using it as a backup when MORECORE fails or
2719	cannot be used. This is worth doing on systems that have "holes" in
2720	address space, so sbrk cannot extend to give contiguous space, but
2721	space is available elsewhere. Note that we ignore mmap max count
2722	and threshold limits, since the space will not be used as a
2723	segregated mmap region.
2724	*/
2725
2726	char *mbrk = MAP_FAILED;
2727	if (mp_.hp_pagesize > `0`)
2728	mbrk = sysmalloc_mmap_fallback (s: &size, nb, old_size,
2729	minsize: mp_.hp_pagesize, pagesize: mp_.hp_pagesize,
2730	extra_flags: mp_.hp_flags, av);
2731	if (mbrk == MAP_FAILED)
2732	mbrk = sysmalloc_mmap_fallback (s: &size, nb, old_size, MMAP_AS_MORECORE_SIZE,
2733	pagesize, extra_flags: `0`, av);
2734	if (mbrk != MAP_FAILED)
2735	{
2736	/ We do not need, and cannot use, another sbrk call to find end /
2737	brk = mbrk;
2738	snd_brk = brk + size;
2739	}
2740	}
2741
2742	if (brk != (char *) (MORECORE_FAILURE))
2743	{
2744	if (mp_.sbrk_base == `0`)
2745	mp_.sbrk_base = brk;
2746	av->system_mem += size;
2747
2748	/*
2749	If MORECORE extends previous space, we can likewise extend top size.
2750	*/
2751
2752	if (brk == old_end && snd_brk == (char *) (MORECORE_FAILURE))
2753	set_head (old_top, (size + old_size) \| PREV_INUSE);
2754
2755	else if (contiguous (av) && old_size && brk < old_end)
2756	/ Oops! Someone else killed our space.. Can't touch anything. /
2757	malloc_printerr (str: "break adjusted to free malloc space");
2758
2759	/*
2760	Otherwise, make adjustments:
2761
2762	* If the first time through or noncontiguous, we need to call sbrk
2763	just to find out where the end of memory lies.
2764
2765	* We need to ensure that all returned chunks from malloc will meet
2766	MALLOC_ALIGNMENT
2767
2768	* If there was an intervening foreign sbrk, we need to adjust sbrk
2769	request size to account for fact that we will not be able to
2770	combine new space with existing space in old_top.
2771
2772	* Almost all systems internally allocate whole pages at a time, in
2773	which case we might as well use the whole last page of request.
2774	So we allocate enough more memory to hit a page boundary now,
2775	which in turn causes future contiguous calls to page-align.
2776	*/
2777
2778	else
2779	{
2780	front_misalign = `0`;
2781	end_misalign = `0`;
2782	correction = `0`;
2783	aligned_brk = brk;
2784
2785	/ handle contiguous cases /
2786	if (contiguous (av))
2787	{
2788	/ Count foreign sbrk as system_mem. /
2789	if (old_size)
2790	av->system_mem += brk - old_end;
2791
2792	/ Guarantee alignment of first new chunk made from this space /
2793
2794	front_misalign = (INTERNAL_SIZE_T) chunk2mem (brk) & MALLOC_ALIGN_MASK;
2795	if (front_misalign > `0`)
2796	{
2797	/*
2798	Skip over some bytes to arrive at an aligned position.
2799	We don't need to specially mark these wasted front bytes.
2800	They will never be accessed anyway because
2801	prev_inuse of av->top (and any chunk created from its start)
2802	is always true after initialization.
2803	*/
2804
2805	correction = MALLOC_ALIGNMENT - front_misalign;
2806	aligned_brk += correction;
2807	}
2808
2809	/*
2810	If this isn't adjacent to existing space, then we will not
2811	be able to merge with old_top space, so must add to 2nd request.
2812	*/
2813
2814	correction += old_size;
2815
2816	/ Extend the end address to hit a page boundary /
2817	end_misalign = (INTERNAL_SIZE_T) (brk + size + correction);
2818	correction += (ALIGN_UP (end_misalign, pagesize)) - end_misalign;
2819
2820	assert (correction >= `0`);
2821	snd_brk = (char *) (MORECORE (increment: correction));
2822
2823	/*
2824	If can't allocate correction, try to at least find out current
2825	brk. It might be enough to proceed without failing.
2826
2827	Note that if second sbrk did NOT fail, we assume that space
2828	is contiguous with first sbrk. This is a safe assumption unless
2829	program is multithreaded but doesn't use locks and a foreign sbrk
2830	occurred between our first and second calls.
2831	*/
2832
2833	if (snd_brk == (char *) (MORECORE_FAILURE))
2834	{
2835	correction = `0`;
2836	snd_brk = (char *) (MORECORE (increment: `0`));
2837	}
2838	else
2839	madvise_thp (p: snd_brk, size: correction);
2840	}
2841
2842	/ handle non-contiguous cases /
2843	else
2844	{
2845	if (MALLOC_ALIGNMENT == CHUNK_HDR_SZ)
2846	/ MORECORE/mmap must correctly align /
2847	assert (((unsigned long) chunk2mem (brk) & MALLOC_ALIGN_MASK) == `0`);
2848	else
2849	{
2850	front_misalign = (INTERNAL_SIZE_T) chunk2mem (brk) & MALLOC_ALIGN_MASK;
2851	if (front_misalign > `0`)
2852	{
2853	/*
2854	Skip over some bytes to arrive at an aligned position.
2855	We don't need to specially mark these wasted front bytes.
2856	They will never be accessed anyway because
2857	prev_inuse of av->top (and any chunk created from its start)
2858	is always true after initialization.
2859	*/
2860
2861	aligned_brk += MALLOC_ALIGNMENT - front_misalign;
2862	}
2863	}
2864
2865	/ Find out current end of memory /
2866	if (snd_brk == (char *) (MORECORE_FAILURE))
2867	{
2868	snd_brk = (char *) (MORECORE (increment: `0`));
2869	}
2870	}
2871
2872	/ Adjust top based on results of second sbrk /
2873	if (snd_brk != (char *) (MORECORE_FAILURE))
2874	{
2875	av->top = (mchunkptr) aligned_brk;
2876	set_head (av->top, (snd_brk - aligned_brk + correction) \| PREV_INUSE);
2877	av->system_mem += correction;
2878
2879	/*
2880	If not the first time through, we either have a
2881	gap due to foreign sbrk or a non-contiguous region. Insert a
2882	double fencepost at old_top to prevent consolidation with space
2883	we don't own. These fenceposts are artificial chunks that are
2884	marked as inuse and are in any case too small to use. We need
2885	two to make sizes and alignments work out.
2886	*/
2887
2888	if (old_size != `0`)
2889	{
2890	/*
2891	Shrink old_top to insert fenceposts, keeping size a
2892	multiple of MALLOC_ALIGNMENT. We know there is at least
2893	enough space in old_top to do this.
2894	*/
2895	old_size = (old_size - `2` * CHUNK_HDR_SZ) & ~MALLOC_ALIGN_MASK;
2896	set_head (old_top, old_size \| PREV_INUSE);
2897
2898	/*
2899	Note that the following assignments completely overwrite
2900	old_top when old_size was previously MINSIZE. This is
2901	intentional. We need the fencepost, even if old_top otherwise gets
2902	lost.
2903	*/
2904	set_head (chunk_at_offset (old_top, old_size),
2905	CHUNK_HDR_SZ \| PREV_INUSE);
2906	set_head (chunk_at_offset (old_top,
2907	old_size + CHUNK_HDR_SZ),
2908	CHUNK_HDR_SZ \| PREV_INUSE);
2909
2910	/ If possible, release the rest. /
2911	if (old_size >= MINSIZE)
2912	{
2913	_int_free (av, old_top, `1`);
2914	}
2915	}
2916	}
2917	}
2918	}
2919	} / if (av != &main_arena) /
2920
2921	if ((unsigned long) av->system_mem > (unsigned long) (av->max_system_mem))
2922	av->max_system_mem = av->system_mem;
2923	check_malloc_state (av);
2924
2925	/ finally, do the allocation /
2926	p = av->top;
2927	size = chunksize (p);
2928
2929	/ check that one of the above allocation paths succeeded /
2930	if ((unsigned long) (size) >= (unsigned long) (nb + MINSIZE))
2931	{
2932	remainder_size = size - nb;
2933	remainder = chunk_at_offset (p, nb);
2934	av->top = remainder;
2935	set_head (p, nb \| PREV_INUSE \| (av != &main_arena ? NON_MAIN_ARENA : `0`));
2936	set_head (remainder, remainder_size \| PREV_INUSE);
2937	check_malloced_chunk (av, p, nb);
2938	return chunk2mem (p);
2939	}
2940
2941	/ catch all failure paths /
2942	__set_errno (ENOMEM);
2943	return `0`;
2944	}
2945
2946
2947	/*
2948	systrim is an inverse of sorts to sysmalloc. It gives memory back
2949	to the system (via negative arguments to sbrk) if there is unused
2950	memory at the `high' end of the malloc pool. It is called
2951	automatically by free() when top space exceeds the trim
2952	threshold. It is also called by the public malloc_trim routine. It
2953	returns 1 if it actually released any memory, else 0.
2954	*/
2955
2956	static int
2957	systrim (size_t pad, mstate av)
2958	{
2959	long top_size; / Amount of top-most memory /
2960	long extra; / Amount to release /
2961	long released; / Amount actually released /
2962	char current_brk; /* address returned by pre-check sbrk call /
2963	char new_brk; /* address returned by post-check sbrk call /
2964	long top_area;
2965
2966	top_size = chunksize (av->top);
2967
2968	top_area = top_size - MINSIZE - `1`;
2969	if (top_area <= pad)
2970	return `0`;
2971
2972	/ Release in pagesize units and round down to the nearest page. /
2973	#ifdef MADV_HUGEPAGE
2974	if (__glibc_unlikely (mp_.thp_pagesize != `0`))
2975	extra = ALIGN_DOWN (top_area - pad, mp_.thp_pagesize);
2976	else
2977	#endif
2978	extra = ALIGN_DOWN (top_area - pad, GLRO(dl_pagesize));
2979
2980	if (extra == `0`)
2981	return `0`;
2982
2983	/*
2984	Only proceed if end of memory is where we last set it.
2985	This avoids problems if there were foreign sbrk calls.
2986	*/
2987	current_brk = (char *) (MORECORE (increment: `0`));
2988	if (current_brk == (char *) (av->top) + top_size)
2989	{
2990	/*
2991	Attempt to release memory. We ignore MORECORE return value,
2992	and instead call again to find out where new end of memory is.
2993	This avoids problems if first call releases less than we asked,
2994	of if failure somehow altered brk value. (We could still
2995	encounter problems if it altered brk in some very bad way,
2996	but the only thing we can do is adjust anyway, which will cause
2997	some downstream failure.)
2998	*/
2999
3000	MORECORE (increment: -extra);
3001	new_brk = (char *) (MORECORE (increment: `0`));
3002
3003	LIBC_PROBE (memory_sbrk_less, `2`, new_brk, extra);
3004
3005	if (new_brk != (char *) MORECORE_FAILURE)
3006	{
3007	released = (long) (current_brk - new_brk);
3008
3009	if (released != `0`)
3010	{
3011	/ Success. Adjust top. /
3012	av->system_mem -= released;
3013	set_head (av->top, (top_size - released) \| PREV_INUSE);
3014	check_malloc_state (av);
3015	return `1`;
3016	}
3017	}
3018	}
3019	return `0`;
3020	}
3021
3022	static void
3023	munmap_chunk (mchunkptr p)
3024	{
3025	size_t pagesize = GLRO (dl_pagesize);
3026	INTERNAL_SIZE_T size = chunksize (p);
3027
3028	assert (chunk_is_mmapped (p));
3029
3030	uintptr_t mem = (uintptr_t) chunk2mem (p);
3031	uintptr_t block = (uintptr_t) p - prev_size (p);
3032	size_t total_size = prev_size (p) + size;
3033	/ Unfortunately we have to do the compilers job by hand here. Normally*
3034	we would test BLOCK and TOTAL-SIZE separately for compliance with the
3035	page size. But gcc does not recognize the optimization possibility
3036	(in the moment at least) so we combine the two values into one before
3037	the bit test. /*
3038	if (__glibc_unlikely ((block \| total_size) & (pagesize - `1`)) != `0`
3039	\|\| __glibc_unlikely (!powerof2 (mem & (pagesize - `1`))))
3040	malloc_printerr (str: "munmap_chunk(): invalid pointer");
3041
3042	atomic_fetch_add_relaxed (&mp_.n_mmaps, -`1`);
3043	atomic_fetch_add_relaxed (&mp_.mmapped_mem, -total_size);
3044
3045	/ If munmap failed the process virtual memory address space is in a*
3046	bad shape. Just leave the block hanging around, the process will
3047	terminate shortly anyway since not much can be done. /*
3048	__munmap (addr: (char *) block, len: total_size);
3049	}
3050
3051	#if HAVE_MREMAP
3052
3053	static mchunkptr
3054	mremap_chunk (mchunkptr p, size_t new_size)
3055	{
3056	size_t pagesize = GLRO (dl_pagesize);
3057	INTERNAL_SIZE_T offset = prev_size (p);
3058	INTERNAL_SIZE_T size = chunksize (p);
3059	char *cp;
3060
3061	assert (chunk_is_mmapped (p));
3062
3063	uintptr_t block = (uintptr_t) p - offset;
3064	uintptr_t mem = (uintptr_t) chunk2mem(p);
3065	size_t total_size = offset + size;
3066	if (__glibc_unlikely ((block \| total_size) & (pagesize - `1`)) != `0`
3067	\|\| __glibc_unlikely (!powerof2 (mem & (pagesize - `1`))))
3068	malloc_printerr(str: "mremap_chunk(): invalid pointer");
3069
3070	/ Note the extra SIZE_SZ overhead as in mmap_chunk(). /
3071	new_size = ALIGN_UP (new_size + offset + SIZE_SZ, pagesize);
3072
3073	/ No need to remap if the number of pages does not change. /
3074	if (total_size == new_size)
3075	return p;
3076
3077	cp = (char ) __mremap (addr: (char* *) block, old_len: total_size, new_len: new_size,
3078	MREMAP_MAYMOVE);
3079
3080	if (cp == MAP_FAILED)
3081	return `0`;
3082
3083	madvise_thp (p: cp, size: new_size);
3084
3085	p = (mchunkptr) (cp + offset);
3086
3087	assert (aligned_OK (chunk2mem (p)));
3088
3089	assert (prev_size (p) == offset);
3090	set_head (p, (new_size - offset) \| IS_MMAPPED);
3091
3092	INTERNAL_SIZE_T new;
3093	new = atomic_fetch_add_relaxed (&mp_.mmapped_mem, new_size - size - offset)
3094	+ new_size - size - offset;
3095	atomic_max (&mp_.max_mmapped_mem, new);
3096	return p;
3097	}
3098	#endif /* HAVE_MREMAP */
3099
3100	/------------------------ Public wrappers. --------------------------------/
3101
3102	#if USE_TCACHE
3103
3104	/ We overlay this structure on the user-data portion of a chunk when*
3105	the chunk is stored in the per-thread cache. /*
3106	typedef struct tcache_entry
3107	{
3108	struct tcache_entry *next;
3109	/ This field exists to detect double frees. /
3110	uintptr_t key;
3111	} tcache_entry;
3112
3113	/ There is one of these for each thread, which contains the*
3114	per-thread cache (hence "tcache_perthread_struct"). Keeping
3115	overall size low is mildly important. Note that COUNTS and ENTRIES
3116	are redundant (we could have just counted the linked list each
3117	time), this is for performance reasons. /*
3118	typedef struct tcache_perthread_struct
3119	{
3120	uint16_t counts[TCACHE_MAX_BINS];
3121	tcache_entry *entries[TCACHE_MAX_BINS];
3122	} tcache_perthread_struct;
3123
3124	static __thread bool tcache_shutting_down = false;
3125	static __thread tcache_perthread_struct *tcache = NULL;
3126
3127	/ Process-wide key to try and catch a double-free in the same thread. /
3128	static uintptr_t tcache_key;
3129
3130	/ The value of tcache_key does not really have to be a cryptographically*
3131	secure random number. It only needs to be arbitrary enough so that it does
3132	not collide with values present in applications. If a collision does happen
3133	consistently enough, it could cause a degradation in performance since the
3134	entire list is checked to check if the block indeed has been freed the
3135	second time. The odds of this happening are exceedingly low though, about 1
3136	in 2^wordsize. There is probably a higher chance of the performance
3137	degradation being due to a double free where the first free happened in a
3138	different thread; that's a case this check does not cover. /*
3139	static void
3140	tcache_key_initialize (void)
3141	{
3142	/ We need to use the _nostatus version here, see BZ 29624. /
3143	if (__getrandom_nocancel_nostatus (&tcache_key, sizeof(tcache_key),
3144	GRND_NONBLOCK)
3145	!= sizeof (tcache_key))
3146	{
3147	tcache_key = random_bits ();
3148	#if __WORDSIZE == 64
3149	tcache_key = (tcache_key << `32`) \| random_bits ();
3150	#endif
3151	}
3152	}
3153
3154	/ Caller must ensure that we know tc_idx is valid and there's room*
3155	for more chunks. /*
3156	static __always_inline void
3157	tcache_put (mchunkptr chunk, size_t tc_idx)
3158	{
3159	tcache_entry e = (tcache_entry ) chunk2mem (chunk);
3160
3161	/ Mark this chunk as "in the tcache" so the test in _int_free will*
3162	detect a double free. /*
3163	e->key = tcache_key;
3164
3165	e->next = PROTECT_PTR (&e->next, tcache->entries[tc_idx]);
3166	tcache->entries[tc_idx] = e;
3167	++(tcache->counts[tc_idx]);
3168	}
3169
3170	/ Caller must ensure that we know tc_idx is valid and there's*
3171	available chunks to remove. Removes chunk from the middle of the
3172	list. /*
3173	static __always_inline void *
3174	tcache_get_n (size_t tc_idx, tcache_entry **ep)
3175	{
3176	tcache_entry *e;
3177	if (ep == &(tcache->entries[tc_idx]))
3178	e = *ep;
3179	else
3180	e = REVEAL_PTR (*ep);
3181
3182	if (__glibc_unlikely (!aligned_OK (e)))
3183	malloc_printerr ("malloc(): unaligned tcache chunk detected");
3184
3185	if (ep == &(tcache->entries[tc_idx]))
3186	*ep = REVEAL_PTR (e->next);
3187	else
3188	*ep = PROTECT_PTR (ep, REVEAL_PTR (e->next));
3189
3190	--(tcache->counts[tc_idx]);
3191	e->key = `0`;
3192	return (void *) e;
3193	}
3194
3195	/ Like the above, but removes from the head of the list. /
3196	static __always_inline void *
3197	tcache_get (size_t tc_idx)
3198	{
3199	return tcache_get_n (tc_idx, & tcache->entries[tc_idx]);
3200	}
3201
3202	/ Iterates through the tcache linked list. /
3203	static __always_inline tcache_entry *
3204	tcache_next (tcache_entry *e)
3205	{
3206	return (tcache_entry *) REVEAL_PTR (e->next);
3207	}
3208
3209	static void
3210	tcache_thread_shutdown (void)
3211	{
3212	int i;
3213	tcache_perthread_struct *tcache_tmp = tcache;
3214
3215	tcache_shutting_down = true;
3216
3217	if (!tcache)
3218	return;
3219
3220	/ Disable the tcache and prevent it from being reinitialized. /
3221	tcache = NULL;
3222
3223	/ Free all of the entries and the tcache itself back to the arena*
3224	heap for coalescing. /*
3225	for (i = `0`; i < TCACHE_MAX_BINS; ++i)
3226	{
3227	while (tcache_tmp->entries[i])
3228	{
3229	tcache_entry *e = tcache_tmp->entries[i];
3230	if (__glibc_unlikely (!aligned_OK (e)))
3231	malloc_printerr ("tcache_thread_shutdown(): "
3232	"unaligned tcache chunk detected");
3233	tcache_tmp->entries[i] = REVEAL_PTR (e->next);
3234	__libc_free (e);
3235	}
3236	}
3237
3238	__libc_free (tcache_tmp);
3239	}
3240
3241	static void
3242	tcache_init(void)
3243	{
3244	mstate ar_ptr;
3245	void *victim = `0`;
3246	const size_t bytes = sizeof (tcache_perthread_struct);
3247
3248	if (tcache_shutting_down)
3249	return;
3250
3251	arena_get (ar_ptr, bytes);
3252	victim = _int_malloc (ar_ptr, bytes);
3253	if (!victim && ar_ptr != NULL)
3254	{
3255	ar_ptr = arena_get_retry (ar_ptr, bytes);
3256	victim = _int_malloc (ar_ptr, bytes);
3257	}
3258
3259
3260	if (ar_ptr != NULL)
3261	__libc_lock_unlock (ar_ptr->mutex);
3262
3263	/ In a low memory situation, we may not be able to allocate memory*
3264	- in which case, we just keep trying later. However, we
3265	typically do this very early, so either there is sufficient
3266	memory, or there isn't enough memory to do non-trivial
3267	allocations anyway. /*
3268	if (victim)
3269	{
3270	tcache = (tcache_perthread_struct *) victim;
3271	memset (tcache, `0`, sizeof (tcache_perthread_struct));
3272	}
3273
3274	}
3275
3276	# define MAYBE_INIT_TCACHE() \
3277	if (__glibc_unlikely (tcache == NULL)) \
3278	tcache_init();
3279
3280	#else /* !USE_TCACHE */
3281	# define MAYBE_INIT_TCACHE()
3282
3283	static void
3284	tcache_thread_shutdown (void)
3285	{
3286	/ Nothing to do if there is no thread cache. /
3287	}
3288
3289	#endif /* !USE_TCACHE */
3290
3291	#if IS_IN (libc)
3292	void *
3293	__libc_malloc (size_t bytes)
3294	{
3295	mstate ar_ptr;
3296	void *victim;
3297
3298	_Static_assert (PTRDIFF_MAX <= SIZE_MAX / `2`,
3299	"PTRDIFF_MAX is not more than half of SIZE_MAX");
3300
3301	if (!__malloc_initialized)
3302	ptmalloc_init ();
3303	#if USE_TCACHE
3304	/ int_free also calls request2size, be careful to not pad twice. /
3305	size_t tbytes = checked_request2size (bytes);
3306	if (tbytes == `0`)
3307	{
3308	__set_errno (ENOMEM);
3309	return NULL;
3310	}
3311	size_t tc_idx = csize2tidx (tbytes);
3312
3313	MAYBE_INIT_TCACHE ();
3314
3315	DIAG_PUSH_NEEDS_COMMENT;
3316	if (tc_idx < mp_.tcache_bins
3317	&& tcache != NULL
3318	&& tcache->counts[tc_idx] > `0`)
3319	{
3320	victim = tcache_get (tc_idx);
3321	return tag_new_usable (victim);
3322	}
3323	DIAG_POP_NEEDS_COMMENT;
3324	#endif
3325
3326	if (SINGLE_THREAD_P)
3327	{
3328	victim = tag_new_usable (_int_malloc (&main_arena, bytes));
3329	assert (!victim \|\| chunk_is_mmapped (mem2chunk (victim)) \|\|
3330	&main_arena == arena_for_chunk (mem2chunk (victim)));
3331	return victim;
3332	}
3333
3334	arena_get (ar_ptr, bytes);
3335
3336	victim = _int_malloc (ar_ptr, bytes);
3337	/ Retry with another arena only if we were able to find a usable arena*
3338	before. /*
3339	if (!victim && ar_ptr != NULL)
3340	{
3341	LIBC_PROBE (memory_malloc_retry, `1`, bytes);
3342	ar_ptr = arena_get_retry (ar_ptr, bytes);
3343	victim = _int_malloc (ar_ptr, bytes);
3344	}
3345
3346	if (ar_ptr != NULL)
3347	__libc_lock_unlock (ar_ptr->mutex);
3348
3349	victim = tag_new_usable (victim);
3350
3351	assert (!victim \|\| chunk_is_mmapped (mem2chunk (victim)) \|\|
3352	ar_ptr == arena_for_chunk (mem2chunk (victim)));
3353	return victim;
3354	}
3355	libc_hidden_def (__libc_malloc)
3356
3357	void
3358	__libc_free (void *mem)
3359	{
3360	mstate ar_ptr;
3361	mchunkptr p; / chunk corresponding to mem /
3362
3363	if (mem == `0`) / free(0) has no effect /
3364	return;
3365
3366	/ Quickly check that the freed pointer matches the tag for the memory.*
3367	This gives a useful double-free detection. /*
3368	if (__glibc_unlikely (mtag_enabled))
3369	(volatile* char *)mem;
3370
3371	int err = errno;
3372
3373	p = mem2chunk (mem);
3374
3375	if (chunk_is_mmapped (p)) / release mmapped memory. /
3376	{
3377	/ See if the dynamic brk/mmap threshold needs adjusting.*
3378	Dumped fake mmapped chunks do not affect the threshold. /*
3379	if (!mp_.no_dyn_threshold
3380	&& chunksize_nomask (p) > mp_.mmap_threshold
3381	&& chunksize_nomask (p) <= DEFAULT_MMAP_THRESHOLD_MAX)
3382	{
3383	mp_.mmap_threshold = chunksize (p);
3384	mp_.trim_threshold = `2` * mp_.mmap_threshold;
3385	LIBC_PROBE (memory_mallopt_free_dyn_thresholds, `2`,
3386	mp_.mmap_threshold, mp_.trim_threshold);
3387	}
3388	munmap_chunk (p);
3389	}
3390	else
3391	{
3392	MAYBE_INIT_TCACHE ();
3393
3394	/ Mark the chunk as belonging to the library again. /
3395	(void)tag_region (chunk2mem (p), memsize (p));
3396
3397	ar_ptr = arena_for_chunk (p);
3398	_int_free (ar_ptr, p, `0`);
3399	}
3400
3401	__set_errno (err);
3402	}
3403	libc_hidden_def (__libc_free)
3404
3405	void *
3406	__libc_realloc (void *oldmem, size_t bytes)
3407	{
3408	mstate ar_ptr;
3409	INTERNAL_SIZE_T nb; / padded request size /
3410
3411	void newp; /* chunk to return /
3412
3413	if (!__malloc_initialized)
3414	ptmalloc_init ();
3415
3416	#if REALLOC_ZERO_BYTES_FREES
3417	if (bytes == `0` && oldmem != NULL)
3418	{
3419	__libc_free (oldmem); return `0`;
3420	}
3421	#endif
3422
3423	/ realloc of null is supposed to be same as malloc /
3424	if (oldmem == `0`)
3425	return __libc_malloc (bytes);
3426
3427	/ Perform a quick check to ensure that the pointer's tag matches the*
3428	memory's tag. /*
3429	if (__glibc_unlikely (mtag_enabled))
3430	(volatile* char*) oldmem;
3431
3432	/ chunk corresponding to oldmem /
3433	const mchunkptr oldp = mem2chunk (oldmem);
3434
3435	/ Return the chunk as is if the request grows within usable bytes, typically*
3436	into the alignment padding. We want to avoid reusing the block for
3437	shrinkages because it ends up unnecessarily fragmenting the address space.
3438	This is also why the heuristic misses alignment padding for THP for
3439	now. /*
3440	size_t usable = musable (oldmem);
3441	if (bytes <= usable)
3442	{
3443	size_t difference = usable - bytes;
3444	if ((unsigned long) difference < `2` * sizeof (INTERNAL_SIZE_T)
3445	\|\| (chunk_is_mmapped (oldp) && difference <= GLRO (dl_pagesize)))
3446	return oldmem;
3447	}
3448
3449	/ its size /
3450	const INTERNAL_SIZE_T oldsize = chunksize (oldp);
3451
3452	if (chunk_is_mmapped (oldp))
3453	ar_ptr = NULL;
3454	else
3455	{
3456	MAYBE_INIT_TCACHE ();
3457	ar_ptr = arena_for_chunk (oldp);
3458	}
3459
3460	/ Little security check which won't hurt performance: the allocator*
3461	never wraps around at the end of the address space. Therefore
3462	we can exclude some size values which might appear here by
3463	accident or by "design" from some intruder. /*
3464	if ((__builtin_expect ((uintptr_t) oldp > (uintptr_t) -oldsize, `0`)
3465	\|\| __builtin_expect (misaligned_chunk (oldp), `0`)))
3466	malloc_printerr ("realloc(): invalid pointer");
3467
3468	nb = checked_request2size (bytes);
3469	if (nb == `0`)
3470	{
3471	__set_errno (ENOMEM);
3472	return NULL;
3473	}
3474
3475	if (chunk_is_mmapped (oldp))
3476	{
3477	void *newmem;
3478
3479	#if HAVE_MREMAP
3480	newp = mremap_chunk (oldp, nb);
3481	if (newp)
3482	{
3483	void *newmem = chunk2mem_tag (newp);
3484	/ Give the new block a different tag. This helps to ensure*
3485	that stale handles to the previous mapping are not
3486	reused. There's a performance hit for both us and the
3487	caller for doing this, so we might want to
3488	reconsider. /*
3489	return tag_new_usable (newmem);
3490	}
3491	#endif
3492	/ Note the extra SIZE_SZ overhead. /
3493	if (oldsize - SIZE_SZ >= nb)
3494	return oldmem; / do nothing /
3495
3496	/ Must alloc, copy, free. /
3497	newmem = __libc_malloc (bytes);
3498	if (newmem == `0`)
3499	return `0`; / propagate failure /
3500
3501	memcpy (newmem, oldmem, oldsize - CHUNK_HDR_SZ);
3502	munmap_chunk (oldp);
3503	return newmem;
3504	}
3505
3506	if (SINGLE_THREAD_P)
3507	{
3508	newp = _int_realloc (ar_ptr, oldp, oldsize, nb);
3509	assert (!newp \|\| chunk_is_mmapped (mem2chunk (newp)) \|\|
3510	ar_ptr == arena_for_chunk (mem2chunk (newp)));
3511
3512	return newp;
3513	}
3514
3515	__libc_lock_lock (ar_ptr->mutex);
3516
3517	newp = _int_realloc (ar_ptr, oldp, oldsize, nb);
3518
3519	__libc_lock_unlock (ar_ptr->mutex);
3520	assert (!newp \|\| chunk_is_mmapped (mem2chunk (newp)) \|\|
3521	ar_ptr == arena_for_chunk (mem2chunk (newp)));
3522
3523	if (newp == NULL)
3524	{
3525	/ Try harder to allocate memory in other arenas. /
3526	LIBC_PROBE (memory_realloc_retry, `2`, bytes, oldmem);
3527	newp = __libc_malloc (bytes);
3528	if (newp != NULL)
3529	{
3530	size_t sz = memsize (oldp);
3531	memcpy (newp, oldmem, sz);
3532	(void) tag_region (chunk2mem (oldp), sz);
3533	_int_free (ar_ptr, oldp, `0`);
3534	}
3535	}
3536
3537	return newp;
3538	}
3539	libc_hidden_def (__libc_realloc)
3540
3541	void *
3542	__libc_memalign (size_t alignment, size_t bytes)
3543	{
3544	if (!__malloc_initialized)
3545	ptmalloc_init ();
3546
3547	void *address = RETURN_ADDRESS (`0`);
3548	return _mid_memalign (alignment, bytes, address);
3549	}
3550	libc_hidden_def (__libc_memalign)
3551
3552	/ For ISO C17. /
3553	void *
3554	weak_function
3555	aligned_alloc (size_t alignment, size_t bytes)
3556	{
3557	if (!__malloc_initialized)
3558	ptmalloc_init ();
3559
3560	/ Similar to memalign, but starting with ISO C17 the standard*
3561	requires an error for alignments that are not supported by the
3562	implementation. Valid alignments for the current implementation
3563	are non-negative powers of two. /*
3564	if (!powerof2 (alignment) \|\| alignment == `0`)
3565	{
3566	__set_errno (EINVAL);
3567	return `0`;
3568	}
3569
3570	void *address = RETURN_ADDRESS (`0`);
3571	return _mid_memalign (alignment, bytes, address);
3572	}
3573
3574	static void *
3575	_mid_memalign (size_t alignment, size_t bytes, void *address)
3576	{
3577	mstate ar_ptr;
3578	void *p;
3579
3580	/ If we need less alignment than we give anyway, just relay to malloc. /
3581	if (alignment <= MALLOC_ALIGNMENT)
3582	return __libc_malloc (bytes);
3583
3584	/ Otherwise, ensure that it is at least a minimum chunk size /
3585	if (alignment < MINSIZE)
3586	alignment = MINSIZE;
3587
3588	/ If the alignment is greater than SIZE_MAX / 2 + 1 it cannot be a*
3589	power of 2 and will cause overflow in the check below. /*
3590	if (alignment > SIZE_MAX / `2` + `1`)
3591	{
3592	__set_errno (EINVAL);
3593	return `0`;
3594	}
3595
3596
3597	/ Make sure alignment is power of 2. /
3598	if (!powerof2 (alignment))
3599	{
3600	size_t a = MALLOC_ALIGNMENT * `2`;
3601	while (a < alignment)
3602	a <<= `1`;
3603	alignment = a;
3604	}
3605
3606	#if USE_TCACHE
3607	{
3608	size_t tbytes;
3609	tbytes = checked_request2size (bytes);
3610	if (tbytes == `0`)
3611	{
3612	__set_errno (ENOMEM);
3613	return NULL;
3614	}
3615	size_t tc_idx = csize2tidx (tbytes);
3616
3617	if (tc_idx < mp_.tcache_bins
3618	&& tcache != NULL
3619	&& tcache->counts[tc_idx] > `0`)
3620	{
3621	/ The tcache itself isn't encoded, but the chain is. /
3622	tcache_entry **tep = & tcache->entries[tc_idx];
3623	tcache_entry te = tep;
3624	while (te != NULL && !PTR_IS_ALIGNED (te, alignment))
3625	{
3626	tep = & (te->next);
3627	te = tcache_next (te);
3628	}
3629	if (te != NULL)
3630	{
3631	void *victim = tcache_get_n (tc_idx, tep);
3632	return tag_new_usable (victim);
3633	}
3634	}
3635	}
3636	#endif
3637
3638	if (SINGLE_THREAD_P)
3639	{
3640	p = _int_memalign (&main_arena, alignment, bytes);
3641	assert (!p \|\| chunk_is_mmapped (mem2chunk (p)) \|\|
3642	&main_arena == arena_for_chunk (mem2chunk (p)));
3643	return tag_new_usable (p);
3644	}
3645
3646	arena_get (ar_ptr, bytes + alignment + MINSIZE);
3647
3648	p = _int_memalign (ar_ptr, alignment, bytes);
3649	if (!p && ar_ptr != NULL)
3650	{
3651	LIBC_PROBE (memory_memalign_retry, `2`, bytes, alignment);
3652	ar_ptr = arena_get_retry (ar_ptr, bytes);
3653	p = _int_memalign (ar_ptr, alignment, bytes);
3654	}
3655
3656	if (ar_ptr != NULL)
3657	__libc_lock_unlock (ar_ptr->mutex);
3658
3659	assert (!p \|\| chunk_is_mmapped (mem2chunk (p)) \|\|
3660	ar_ptr == arena_for_chunk (mem2chunk (p)));
3661	return tag_new_usable (p);
3662	}
3663
3664	void *
3665	__libc_valloc (size_t bytes)
3666	{
3667	if (!__malloc_initialized)
3668	ptmalloc_init ();
3669
3670	void *address = RETURN_ADDRESS (`0`);
3671	size_t pagesize = GLRO (dl_pagesize);
3672	return _mid_memalign (pagesize, bytes, address);
3673	}
3674
3675	void *
3676	__libc_pvalloc (size_t bytes)
3677	{
3678	if (!__malloc_initialized)
3679	ptmalloc_init ();
3680
3681	void *address = RETURN_ADDRESS (`0`);
3682	size_t pagesize = GLRO (dl_pagesize);
3683	size_t rounded_bytes;
3684	/ ALIGN_UP with overflow check. /
3685	if (__glibc_unlikely (__builtin_add_overflow (bytes,
3686	pagesize - `1`,
3687	&rounded_bytes)))
3688	{
3689	__set_errno (ENOMEM);
3690	return `0`;
3691	}
3692	rounded_bytes = rounded_bytes & -(pagesize - `1`);
3693
3694	return _mid_memalign (pagesize, rounded_bytes, address);
3695	}
3696
3697	void *
3698	__libc_calloc (size_t n, size_t elem_size)
3699	{
3700	mstate av;
3701	mchunkptr oldtop;
3702	INTERNAL_SIZE_T sz, oldtopsize;
3703	void *mem;
3704	unsigned long clearsize;
3705	unsigned long nclears;
3706	INTERNAL_SIZE_T *d;
3707	ptrdiff_t bytes;
3708
3709	if (__glibc_unlikely (__builtin_mul_overflow (n, elem_size, &bytes)))
3710	{
3711	__set_errno (ENOMEM);
3712	return NULL;
3713	}
3714
3715	sz = bytes;
3716
3717	if (!__malloc_initialized)
3718	ptmalloc_init ();
3719
3720	MAYBE_INIT_TCACHE ();
3721
3722	if (SINGLE_THREAD_P)
3723	av = &main_arena;
3724	else
3725	arena_get (av, sz);
3726
3727	if (av)
3728	{
3729	/ Check if we hand out the top chunk, in which case there may be no*
3730	need to clear. /*
3731	#if MORECORE_CLEARS
3732	oldtop = top (av);
3733	oldtopsize = chunksize (top (av));
3734	# if MORECORE_CLEARS < 2
3735	/ Only newly allocated memory is guaranteed to be cleared. /
3736	if (av == &main_arena &&
3737	oldtopsize < mp_.sbrk_base + av->max_system_mem - (char *) oldtop)
3738	oldtopsize = (mp_.sbrk_base + av->max_system_mem - (char *) oldtop);
3739	# endif
3740	if (av != &main_arena)
3741	{
3742	heap_info *heap = heap_for_ptr (oldtop);
3743	if (oldtopsize < (char ) heap + heap->mprotect_size - (char* *) oldtop)
3744	oldtopsize = (char ) heap + heap->mprotect_size - (char* *) oldtop;
3745	}
3746	#endif
3747	}
3748	else
3749	{
3750	/ No usable arenas. /
3751	oldtop = `0`;
3752	oldtopsize = `0`;
3753	}
3754	mem = _int_malloc (av, sz);
3755
3756	assert (!mem \|\| chunk_is_mmapped (mem2chunk (mem)) \|\|
3757	av == arena_for_chunk (mem2chunk (mem)));
3758
3759	if (!SINGLE_THREAD_P)
3760	{
3761	if (mem == `0` && av != NULL)
3762	{
3763	LIBC_PROBE (memory_calloc_retry, `1`, sz);
3764	av = arena_get_retry (av, sz);
3765	mem = _int_malloc (av, sz);
3766	}
3767
3768	if (av != NULL)
3769	__libc_lock_unlock (av->mutex);
3770	}
3771
3772	/ Allocation failed even after a retry. /
3773	if (mem == `0`)
3774	return `0`;
3775
3776	mchunkptr p = mem2chunk (mem);
3777
3778	/ If we are using memory tagging, then we need to set the tags*
3779	regardless of MORECORE_CLEARS, so we zero the whole block while
3780	doing so. /*
3781	if (__glibc_unlikely (mtag_enabled))
3782	return tag_new_zero_region (mem, memsize (p));
3783
3784	INTERNAL_SIZE_T csz = chunksize (p);
3785
3786	/ Two optional cases in which clearing not necessary /
3787	if (chunk_is_mmapped (p))
3788	{
3789	if (__builtin_expect (perturb_byte, `0`))
3790	return memset (mem, `0`, sz);
3791
3792	return mem;
3793	}
3794
3795	#if MORECORE_CLEARS
3796	if (perturb_byte == `0` && (p == oldtop && csz > oldtopsize))
3797	{
3798	/ clear only the bytes from non-freshly-sbrked memory /
3799	csz = oldtopsize;
3800	}
3801	#endif
3802
3803	/ Unroll clear of <= 36 bytes (72 if 8byte sizes). We know that*
3804	contents have an odd number of INTERNAL_SIZE_T-sized words;
3805	minimally 3. /*
3806	d = (INTERNAL_SIZE_T *) mem;
3807	clearsize = csz - SIZE_SZ;
3808	nclears = clearsize / sizeof (INTERNAL_SIZE_T);
3809	assert (nclears >= `3`);
3810
3811	if (nclears > `9`)
3812	return memset (d, `0`, clearsize);
3813
3814	else
3815	{
3816	*(d + `0`) = `0`;
3817	*(d + `1`) = `0`;
3818	*(d + `2`) = `0`;
3819	if (nclears > `4`)
3820	{
3821	*(d + `3`) = `0`;
3822	*(d + `4`) = `0`;
3823	if (nclears > `6`)
3824	{
3825	*(d + `5`) = `0`;
3826	*(d + `6`) = `0`;
3827	if (nclears > `8`)
3828	{
3829	*(d + `7`) = `0`;
3830	*(d + `8`) = `0`;
3831	}
3832	}
3833	}
3834	}
3835
3836	return mem;
3837	}
3838	#endif /* IS_IN (libc) */
3839
3840	/*
3841	------------------------------ malloc ------------------------------
3842	*/
3843
3844	static void *
3845	_int_malloc (mstate av, size_t bytes)
3846	{
3847	INTERNAL_SIZE_T nb; / normalized request size /
3848	unsigned int idx; / associated bin index /
3849	mbinptr bin; / associated bin /
3850
3851	mchunkptr victim; / inspected/selected chunk /
3852	INTERNAL_SIZE_T size; / its size /
3853	int victim_index; / its bin index /
3854
3855	mchunkptr remainder; / remainder from a split /
3856	unsigned long remainder_size; / its size /
3857
3858	unsigned int block; / bit map traverser /
3859	unsigned int bit; / bit map traverser /
3860	unsigned int map; / current word of binmap /
3861
3862	mchunkptr fwd; / misc temp for linking /
3863	mchunkptr bck; / misc temp for linking /
3864
3865	#if USE_TCACHE
3866	size_t tcache_unsorted_count; / count of unsorted chunks processed /
3867	#endif
3868
3869	/*
3870	Convert request size to internal form by adding SIZE_SZ bytes
3871	overhead plus possibly more to obtain necessary alignment and/or
3872	to obtain a size of at least MINSIZE, the smallest allocatable
3873	size. Also, checked_request2size returns false for request sizes
3874	that are so large that they wrap around zero when padded and
3875	aligned.
3876	*/
3877
3878	nb = checked_request2size (req: bytes);
3879	if (nb == `0`)
3880	{
3881	__set_errno (ENOMEM);
3882	return NULL;
3883	}
3884
3885	/ There are no usable arenas. Fall back to sysmalloc to get a chunk from*
3886	mmap. /*
3887	if (__glibc_unlikely (av == NULL))
3888	{
3889	void *p = sysmalloc (nb, av);
3890	if (p != NULL)
3891	alloc_perturb (p, n: bytes);
3892	return p;
3893	}
3894
3895	/*
3896	If the size qualifies as a fastbin, first check corresponding bin.
3897	This code is safe to execute even if av is not yet initialized, so we
3898	can try it without checking, which saves some time on this fast path.
3899	*/
3900
3901	#define REMOVE_FB(fb, victim, pp) \
3902	do \
3903	{ \
3904	victim = pp; \
3905	if (victim == NULL) \
3906	break; \
3907	pp = REVEAL_PTR (victim->fd); \
3908	if (__glibc_unlikely (pp != NULL && misaligned_chunk (pp))) \
3909	malloc_printerr ("malloc(): unaligned fastbin chunk detected"); \
3910	} \
3911	while ((pp = catomic_compare_and_exchange_val_acq (fb, pp, victim)) \
3912	!= victim); \
3913
3914	if ((unsigned long) (nb) <= (unsigned long) (get_max_fast ()))
3915	{
3916	idx = fastbin_index (nb);
3917	mfastbinptr *fb = &fastbin (av, idx);
3918	mchunkptr pp;
3919	victim = *fb;
3920
3921	if (victim != NULL)
3922	{
3923	if (__glibc_unlikely (misaligned_chunk (victim)))
3924	malloc_printerr (str: "malloc(): unaligned fastbin chunk detected 2");
3925
3926	if (SINGLE_THREAD_P)
3927	*fb = REVEAL_PTR (victim->fd);
3928	else
3929	REMOVE_FB (fb, pp, victim);
3930	if (__glibc_likely (victim != NULL))
3931	{
3932	size_t victim_idx = fastbin_index (chunksize (victim));
3933	if (__builtin_expect (victim_idx != idx, `0`))
3934	malloc_printerr (str: "malloc(): memory corruption (fast)");
3935	check_remalloced_chunk (av, victim, nb);
3936	#if USE_TCACHE
3937	/ While we're here, if we see other chunks of the same size,*
3938	stash them in the tcache. /*
3939	size_t tc_idx = csize2tidx (nb);
3940	if (tcache != NULL && tc_idx < mp_.tcache_bins)
3941	{
3942	mchunkptr tc_victim;
3943
3944	/ While bin not empty and tcache not full, copy chunks. /
3945	while (tcache->counts[tc_idx] < mp_.tcache_count
3946	&& (tc_victim = *fb) != NULL)
3947	{
3948	if (__glibc_unlikely (misaligned_chunk (tc_victim)))
3949	malloc_printerr ("malloc(): unaligned fastbin chunk detected 3");
3950	if (SINGLE_THREAD_P)
3951	*fb = REVEAL_PTR (tc_victim->fd);
3952	else
3953	{
3954	REMOVE_FB (fb, pp, tc_victim);
3955	if (__glibc_unlikely (tc_victim == NULL))
3956	break;
3957	}
3958	tcache_put (tc_victim, tc_idx);
3959	}
3960	}
3961	#endif
3962	void *p = chunk2mem (victim);
3963	alloc_perturb (p, n: bytes);
3964	return p;
3965	}
3966	}
3967	}
3968
3969	/*
3970	If a small request, check regular bin. Since these "smallbins"
3971	hold one size each, no searching within bins is necessary.
3972	(For a large request, we need to wait until unsorted chunks are
3973	processed to find best fit. But for small ones, fits are exact
3974	anyway, so we can check now, which is faster.)
3975	*/
3976
3977	if (in_smallbin_range (nb))
3978	{
3979	idx = smallbin_index (nb);
3980	bin = bin_at (av, idx);
3981
3982	if ((victim = last (bin)) != bin)
3983	{
3984	bck = victim->bk;
3985	if (__glibc_unlikely (bck->fd != victim))
3986	malloc_printerr (str: "malloc(): smallbin double linked list corrupted");
3987	set_inuse_bit_at_offset (victim, nb);
3988	bin->bk = bck;
3989	bck->fd = bin;
3990
3991	if (av != &main_arena)
3992	set_non_main_arena (victim);
3993	check_malloced_chunk (av, victim, nb);
3994	#if USE_TCACHE
3995	/ While we're here, if we see other chunks of the same size,*
3996	stash them in the tcache. /*
3997	size_t tc_idx = csize2tidx (nb);
3998	if (tcache != NULL && tc_idx < mp_.tcache_bins)
3999	{
4000	mchunkptr tc_victim;
4001
4002	/ While bin not empty and tcache not full, copy chunks over. /
4003	while (tcache->counts[tc_idx] < mp_.tcache_count
4004	&& (tc_victim = last (bin)) != bin)
4005	{
4006	if (tc_victim != `0`)
4007	{
4008	bck = tc_victim->bk;
4009	set_inuse_bit_at_offset (tc_victim, nb);
4010	if (av != &main_arena)
4011	set_non_main_arena (tc_victim);
4012	bin->bk = bck;
4013	bck->fd = bin;
4014
4015	tcache_put (tc_victim, tc_idx);
4016	}
4017	}
4018	}
4019	#endif
4020	void *p = chunk2mem (victim);
4021	alloc_perturb (p, n: bytes);
4022	return p;
4023	}
4024	}
4025
4026	/*
4027	If this is a large request, consolidate fastbins before continuing.
4028	While it might look excessive to kill all fastbins before
4029	even seeing if there is space available, this avoids
4030	fragmentation problems normally associated with fastbins.
4031	Also, in practice, programs tend to have runs of either small or
4032	large requests, but less often mixtures, so consolidation is not
4033	invoked all that often in most programs. And the programs that
4034	it is called frequently in otherwise tend to fragment.
4035	*/
4036
4037	else
4038	{
4039	idx = largebin_index (nb);
4040	if (atomic_load_relaxed (&av->have_fastchunks))
4041	malloc_consolidate (av);
4042	}
4043
4044	/*
4045	Process recently freed or remaindered chunks, taking one only if
4046	it is exact fit, or, if this a small request, the chunk is remainder from
4047	the most recent non-exact fit. Place other traversed chunks in
4048	bins. Note that this step is the only place in any routine where
4049	chunks are placed in bins.
4050
4051	The outer loop here is needed because we might not realize until
4052	near the end of malloc that we should have consolidated, so must
4053	do so and retry. This happens at most once, and only when we would
4054	otherwise need to expand memory to service a "small" request.
4055	*/
4056
4057	#if USE_TCACHE
4058	INTERNAL_SIZE_T tcache_nb = `0`;
4059	size_t tc_idx = csize2tidx (nb);
4060	if (tcache != NULL && tc_idx < mp_.tcache_bins)
4061	tcache_nb = nb;
4062	int return_cached = `0`;
4063
4064	tcache_unsorted_count = `0`;
4065	#endif
4066
4067	for (;; )
4068	{
4069	int iters = `0`;
4070	while ((victim = unsorted_chunks (av)->bk) != unsorted_chunks (av))
4071	{
4072	bck = victim->bk;
4073	size = chunksize (victim);
4074	mchunkptr next = chunk_at_offset (victim, size);
4075
4076	if (__glibc_unlikely (size <= CHUNK_HDR_SZ)
4077	\|\| __glibc_unlikely (size > av->system_mem))
4078	malloc_printerr (str: "malloc(): invalid size (unsorted)");
4079	if (__glibc_unlikely (chunksize_nomask (next) < CHUNK_HDR_SZ)
4080	\|\| __glibc_unlikely (chunksize_nomask (next) > av->system_mem))
4081	malloc_printerr (str: "malloc(): invalid next size (unsorted)");
4082	if (__glibc_unlikely ((prev_size (next) & ~(SIZE_BITS)) != size))
4083	malloc_printerr (str: "malloc(): mismatching next->prev_size (unsorted)");
4084	if (__glibc_unlikely (bck->fd != victim)
4085	\|\| __glibc_unlikely (victim->fd != unsorted_chunks (av)))
4086	malloc_printerr (str: "malloc(): unsorted double linked list corrupted");
4087	if (__glibc_unlikely (prev_inuse (next)))
4088	malloc_printerr (str: "malloc(): invalid next->prev_inuse (unsorted)");
4089
4090	/*
4091	If a small request, try to use last remainder if it is the
4092	only chunk in unsorted bin. This helps promote locality for
4093	runs of consecutive small requests. This is the only
4094	exception to best-fit, and applies only when there is
4095	no exact fit for a small chunk.
4096	*/
4097
4098	if (in_smallbin_range (nb) &&
4099	bck == unsorted_chunks (av) &&
4100	victim == av->last_remainder &&
4101	(unsigned long) (size) > (unsigned long) (nb + MINSIZE))
4102	{
4103	/ split and reattach remainder /
4104	remainder_size = size - nb;
4105	remainder = chunk_at_offset (victim, nb);
4106	unsorted_chunks (av)->bk = unsorted_chunks (av)->fd = remainder;
4107	av->last_remainder = remainder;
4108	remainder->bk = remainder->fd = unsorted_chunks (av);
4109	if (!in_smallbin_range (remainder_size))
4110	{
4111	remainder->fd_nextsize = NULL;
4112	remainder->bk_nextsize = NULL;
4113	}
4114
4115	set_head (victim, nb \| PREV_INUSE \|
4116	(av != &main_arena ? NON_MAIN_ARENA : `0`));
4117	set_head (remainder, remainder_size \| PREV_INUSE);
4118	set_foot (remainder, remainder_size);
4119
4120	check_malloced_chunk (av, victim, nb);
4121	void *p = chunk2mem (victim);
4122	alloc_perturb (p, n: bytes);
4123	return p;
4124	}
4125
4126	/ remove from unsorted list /
4127	unsorted_chunks (av)->bk = bck;
4128	bck->fd = unsorted_chunks (av);
4129
4130	/ Take now instead of binning if exact fit /
4131
4132	if (size == nb)
4133	{
4134	set_inuse_bit_at_offset (victim, size);
4135	if (av != &main_arena)
4136	set_non_main_arena (victim);
4137	#if USE_TCACHE
4138	/ Fill cache first, return to user only if cache fills.*
4139	We may return one of these chunks later. /*
4140	if (tcache_nb > `0`
4141	&& tcache->counts[tc_idx] < mp_.tcache_count)
4142	{
4143	tcache_put (victim, tc_idx);
4144	return_cached = `1`;
4145	continue;
4146	}
4147	else
4148	{
4149	#endif
4150	check_malloced_chunk (av, victim, nb);
4151	void *p = chunk2mem (victim);
4152	alloc_perturb (p, n: bytes);
4153	return p;
4154	#if USE_TCACHE
4155	}
4156	#endif
4157	}
4158
4159	/ place chunk in bin /
4160
4161	if (in_smallbin_range (size))
4162	{
4163	victim_index = smallbin_index (size);
4164	bck = bin_at (av, victim_index);
4165	fwd = bck->fd;
4166	}
4167	else
4168	{
4169	victim_index = largebin_index (size);
4170	bck = bin_at (av, victim_index);
4171	fwd = bck->fd;
4172
4173	/ maintain large bins in sorted order /
4174	if (fwd != bck)
4175	{
4176	/ Or with inuse bit to speed comparisons /
4177	size \|= PREV_INUSE;
4178	/ if smaller than smallest, bypass loop below /
4179	assert (chunk_main_arena (bck->bk));
4180	if ((unsigned long) (size)
4181	< (unsigned long) chunksize_nomask (bck->bk))
4182	{
4183	fwd = bck;
4184	bck = bck->bk;
4185
4186	victim->fd_nextsize = fwd->fd;
4187	victim->bk_nextsize = fwd->fd->bk_nextsize;
4188	fwd->fd->bk_nextsize = victim->bk_nextsize->fd_nextsize = victim;
4189	}
4190	else
4191	{
4192	assert (chunk_main_arena (fwd));
4193	while ((unsigned long) size < chunksize_nomask (fwd))
4194	{
4195	fwd = fwd->fd_nextsize;
4196	assert (chunk_main_arena (fwd));
4197	}
4198
4199	if ((unsigned long) size
4200	== (unsigned long) chunksize_nomask (fwd))
4201	/ Always insert in the second position. /
4202	fwd = fwd->fd;
4203	else
4204	{
4205	victim->fd_nextsize = fwd;
4206	victim->bk_nextsize = fwd->bk_nextsize;
4207	if (__glibc_unlikely (fwd->bk_nextsize->fd_nextsize != fwd))
4208	malloc_printerr (str: "malloc(): largebin double linked list corrupted (nextsize)");
4209	fwd->bk_nextsize = victim;
4210	victim->bk_nextsize->fd_nextsize = victim;
4211	}
4212	bck = fwd->bk;
4213	if (bck->fd != fwd)
4214	malloc_printerr (str: "malloc(): largebin double linked list corrupted (bk)");
4215	}
4216	}
4217	else
4218	victim->fd_nextsize = victim->bk_nextsize = victim;
4219	}
4220
4221	mark_bin (av, victim_index);
4222	victim->bk = bck;
4223	victim->fd = fwd;
4224	fwd->bk = victim;
4225	bck->fd = victim;
4226
4227	#if USE_TCACHE
4228	/ If we've processed as many chunks as we're allowed while*
4229	filling the cache, return one of the cached ones. /*
4230	++tcache_unsorted_count;
4231	if (return_cached
4232	&& mp_.tcache_unsorted_limit > `0`
4233	&& tcache_unsorted_count > mp_.tcache_unsorted_limit)
4234	{
4235	return tcache_get (tc_idx);
4236	}
4237	#endif
4238
4239	#define MAX_ITERS 10000
4240	if (++iters >= MAX_ITERS)
4241	break;
4242	}
4243
4244	#if USE_TCACHE
4245	/ If all the small chunks we found ended up cached, return one now. /
4246	if (return_cached)
4247	{
4248	return tcache_get (tc_idx);
4249	}
4250	#endif
4251
4252	/*
4253	If a large request, scan through the chunks of current bin in
4254	sorted order to find smallest that fits. Use the skip list for this.
4255	*/
4256
4257	if (!in_smallbin_range (nb))
4258	{
4259	bin = bin_at (av, idx);
4260
4261	/ skip scan if empty or largest chunk is too small /
4262	if ((victim = first (bin)) != bin
4263	&& (unsigned long) chunksize_nomask (victim)
4264	>= (unsigned long) (nb))
4265	{
4266	victim = victim->bk_nextsize;
4267	while (((unsigned long) (size = chunksize (victim)) <
4268	(unsigned long) (nb)))
4269	victim = victim->bk_nextsize;
4270
4271	/ Avoid removing the first entry for a size so that the skip*
4272	list does not have to be rerouted. /*
4273	if (victim != last (bin)
4274	&& chunksize_nomask (victim)
4275	== chunksize_nomask (victim->fd))
4276	victim = victim->fd;
4277
4278	remainder_size = size - nb;
4279	unlink_chunk (av, p: victim);
4280
4281	/ Exhaust /
4282	if (remainder_size < MINSIZE)
4283	{
4284	set_inuse_bit_at_offset (victim, size);
4285	if (av != &main_arena)
4286	set_non_main_arena (victim);
4287	}
4288	/ Split /
4289	else
4290	{
4291	remainder = chunk_at_offset (victim, nb);
4292	/ We cannot assume the unsorted list is empty and therefore*
4293	have to perform a complete insert here. /*
4294	bck = unsorted_chunks (av);
4295	fwd = bck->fd;
4296	if (__glibc_unlikely (fwd->bk != bck))
4297	malloc_printerr (str: "malloc(): corrupted unsorted chunks");
4298	remainder->bk = bck;
4299	remainder->fd = fwd;
4300	bck->fd = remainder;
4301	fwd->bk = remainder;
4302	if (!in_smallbin_range (remainder_size))
4303	{
4304	remainder->fd_nextsize = NULL;
4305	remainder->bk_nextsize = NULL;
4306	}
4307	set_head (victim, nb \| PREV_INUSE \|
4308	(av != &main_arena ? NON_MAIN_ARENA : `0`));
4309	set_head (remainder, remainder_size \| PREV_INUSE);
4310	set_foot (remainder, remainder_size);
4311	}
4312	check_malloced_chunk (av, victim, nb);
4313	void *p = chunk2mem (victim);
4314	alloc_perturb (p, n: bytes);
4315	return p;
4316	}
4317	}
4318
4319	/*
4320	Search for a chunk by scanning bins, starting with next largest
4321	bin. This search is strictly by best-fit; i.e., the smallest
4322	(with ties going to approximately the least recently used) chunk
4323	that fits is selected.
4324
4325	The bitmap avoids needing to check that most blocks are nonempty.
4326	The particular case of skipping all bins during warm-up phases
4327	when no chunks have been returned yet is faster than it might look.
4328	*/
4329
4330	++idx;
4331	bin = bin_at (av, idx);
4332	block = idx2block (idx);
4333	map = av->binmap[block];
4334	bit = idx2bit (idx);
4335
4336	for (;; )
4337	{
4338	/ Skip rest of block if there are no more set bits in this block. /
4339	if (bit > map \|\| bit == `0`)
4340	{
4341	do
4342	{
4343	if (++block >= BINMAPSIZE) / out of bins /
4344	goto use_top;
4345	}
4346	while ((map = av->binmap[block]) == `0`);
4347
4348	bin = bin_at (av, (block << BINMAPSHIFT));
4349	bit = `1`;
4350	}
4351
4352	/ Advance to bin with set bit. There must be one. /
4353	while ((bit & map) == `0`)
4354	{
4355	bin = next_bin (bin);
4356	bit <<= `1`;
4357	assert (bit != `0`);
4358	}
4359
4360	/ Inspect the bin. It is likely to be non-empty /
4361	victim = last (bin);
4362
4363	/ If a false alarm (empty bin), clear the bit. /
4364	if (victim == bin)
4365	{
4366	av->binmap[block] = map &= ~bit; / Write through /
4367	bin = next_bin (bin);
4368	bit <<= `1`;
4369	}
4370
4371	else
4372	{
4373	size = chunksize (victim);
4374
4375	/ We know the first chunk in this bin is big enough to use. /
4376	assert ((unsigned long) (size) >= (unsigned long) (nb));
4377
4378	remainder_size = size - nb;
4379
4380	/ unlink /
4381	unlink_chunk (av, p: victim);
4382
4383	/ Exhaust /
4384	if (remainder_size < MINSIZE)
4385	{
4386	set_inuse_bit_at_offset (victim, size);
4387	if (av != &main_arena)
4388	set_non_main_arena (victim);
4389	}
4390
4391	/ Split /
4392	else
4393	{
4394	remainder = chunk_at_offset (victim, nb);
4395
4396	/ We cannot assume the unsorted list is empty and therefore*
4397	have to perform a complete insert here. /*
4398	bck = unsorted_chunks (av);
4399	fwd = bck->fd;
4400	if (__glibc_unlikely (fwd->bk != bck))
4401	malloc_printerr (str: "malloc(): corrupted unsorted chunks 2");
4402	remainder->bk = bck;
4403	remainder->fd = fwd;
4404	bck->fd = remainder;
4405	fwd->bk = remainder;
4406
4407	/ advertise as last remainder /
4408	if (in_smallbin_range (nb))
4409	av->last_remainder = remainder;
4410	if (!in_smallbin_range (remainder_size))
4411	{
4412	remainder->fd_nextsize = NULL;
4413	remainder->bk_nextsize = NULL;
4414	}
4415	set_head (victim, nb \| PREV_INUSE \|
4416	(av != &main_arena ? NON_MAIN_ARENA : `0`));
4417	set_head (remainder, remainder_size \| PREV_INUSE);
4418	set_foot (remainder, remainder_size);
4419	}
4420	check_malloced_chunk (av, victim, nb);
4421	void *p = chunk2mem (victim);
4422	alloc_perturb (p, n: bytes);
4423	return p;
4424	}
4425	}
4426
4427	use_top:
4428	/*
4429	If large enough, split off the chunk bordering the end of memory
4430	(held in av->top). Note that this is in accord with the best-fit
4431	search rule. In effect, av->top is treated as larger (and thus
4432	less well fitting) than any other available chunk since it can
4433	be extended to be as large as necessary (up to system
4434	limitations).
4435
4436	We require that av->top always exists (i.e., has size >=
4437	MINSIZE) after initialization, so if it would otherwise be
4438	exhausted by current request, it is replenished. (The main
4439	reason for ensuring it exists is that we may need MINSIZE space
4440	to put in fenceposts in sysmalloc.)
4441	*/
4442
4443	victim = av->top;
4444	size = chunksize (victim);
4445
4446	if (__glibc_unlikely (size > av->system_mem))
4447	malloc_printerr (str: "malloc(): corrupted top size");
4448
4449	if ((unsigned long) (size) >= (unsigned long) (nb + MINSIZE))
4450	{
4451	remainder_size = size - nb;
4452	remainder = chunk_at_offset (victim, nb);
4453	av->top = remainder;
4454	set_head (victim, nb \| PREV_INUSE \|
4455	(av != &main_arena ? NON_MAIN_ARENA : `0`));
4456	set_head (remainder, remainder_size \| PREV_INUSE);
4457
4458	check_malloced_chunk (av, victim, nb);
4459	void *p = chunk2mem (victim);
4460	alloc_perturb (p, n: bytes);
4461	return p;
4462	}
4463
4464	/ When we are using atomic ops to free fast chunks we can get*
4465	here for all block sizes. /*
4466	else if (atomic_load_relaxed (&av->have_fastchunks))
4467	{
4468	malloc_consolidate (av);
4469	/ restore original bin index /
4470	if (in_smallbin_range (nb))
4471	idx = smallbin_index (nb);
4472	else
4473	idx = largebin_index (nb);
4474	}
4475
4476	/*
4477	Otherwise, relay to handle system-dependent cases
4478	*/
4479	else
4480	{
4481	void *p = sysmalloc (nb, av);
4482	if (p != NULL)
4483	alloc_perturb (p, n: bytes);
4484	return p;
4485	}
4486	}
4487	}
4488
4489	/*
4490	------------------------------ free ------------------------------
4491	*/
4492
4493	static void
4494	_int_free (mstate av, mchunkptr p, int have_lock)
4495	{
4496	INTERNAL_SIZE_T size; / its size /
4497	mfastbinptr fb; /* associated fastbin /
4498
4499	size = chunksize (p);
4500
4501	/ Little security check which won't hurt performance: the*
4502	allocator never wraps around at the end of the address space.
4503	Therefore we can exclude some size values which might appear
4504	here by accident or by "design" from some intruder. /*
4505	if (__builtin_expect ((uintptr_t) p > (uintptr_t) -size, `0`)
4506	\|\| __builtin_expect (misaligned_chunk (p), `0`))
4507	malloc_printerr (str: "free(): invalid pointer");
4508	/ We know that each chunk is at least MINSIZE bytes in size or a*
4509	multiple of MALLOC_ALIGNMENT. /*
4510	if (__glibc_unlikely (size < MINSIZE \|\| !aligned_OK (size)))
4511	malloc_printerr (str: "free(): invalid size");
4512
4513	check_inuse_chunk(av, p);
4514
4515	#if USE_TCACHE
4516	{
4517	size_t tc_idx = csize2tidx (size);
4518	if (tcache != NULL && tc_idx < mp_.tcache_bins)
4519	{
4520	/ Check to see if it's already in the tcache. /
4521	tcache_entry e = (tcache_entry ) chunk2mem (p);
4522
4523	/ This test succeeds on double free. However, we don't 100%*
4524	trust it (it also matches random payload data at a 1 in
4525	2^<size_t> chance), so verify it's not an unlikely
4526	coincidence before aborting. /*
4527	if (__glibc_unlikely (e->key == tcache_key))
4528	{
4529	tcache_entry *tmp;
4530	size_t cnt = `0`;
4531	LIBC_PROBE (memory_tcache_double_free, `2`, e, tc_idx);
4532	for (tmp = tcache->entries[tc_idx];
4533	tmp;
4534	tmp = REVEAL_PTR (tmp->next), ++cnt)
4535	{
4536	if (cnt >= mp_.tcache_count)
4537	malloc_printerr ("free(): too many chunks detected in tcache");
4538	if (__glibc_unlikely (!aligned_OK (tmp)))
4539	malloc_printerr ("free(): unaligned chunk detected in tcache 2");
4540	if (tmp == e)
4541	malloc_printerr ("free(): double free detected in tcache 2");
4542	/ If we get here, it was a coincidence. We've wasted a*
4543	few cycles, but don't abort. /*
4544	}
4545	}
4546
4547	if (tcache->counts[tc_idx] < mp_.tcache_count)
4548	{
4549	tcache_put (p, tc_idx);
4550	return;
4551	}
4552	}
4553	}
4554	#endif
4555
4556	/*
4557	If eligible, place chunk on a fastbin so it can be found
4558	and used quickly in malloc.
4559	*/
4560
4561	if ((unsigned long)(size) <= (unsigned long)(get_max_fast ())
4562
4563	#if TRIM_FASTBINS
4564	/*
4565	If TRIM_FASTBINS set, don't place chunks
4566	bordering top into fastbins
4567	*/
4568	&& (chunk_at_offset(p, size) != av->top)
4569	#endif
4570	) {
4571
4572	if (__builtin_expect (chunksize_nomask (chunk_at_offset (p, size))
4573	<= CHUNK_HDR_SZ, `0`)
4574	\|\| __builtin_expect (chunksize (chunk_at_offset (p, size))
4575	>= av->system_mem, `0`))
4576	{
4577	bool fail = true;
4578	/ We might not have a lock at this point and concurrent modifications*
4579	of system_mem might result in a false positive. Redo the test after
4580	getting the lock. /*
4581	if (!have_lock)
4582	{
4583	__libc_lock_lock (av->mutex);
4584	fail = (chunksize_nomask (chunk_at_offset (p, size)) <= CHUNK_HDR_SZ
4585	\|\| chunksize (chunk_at_offset (p, size)) >= av->system_mem);
4586	__libc_lock_unlock (av->mutex);
4587	}
4588
4589	if (fail)
4590	malloc_printerr (str: "free(): invalid next size (fast)");
4591	}
4592
4593	free_perturb (chunk2mem(p), n: size - CHUNK_HDR_SZ);
4594
4595	atomic_store_relaxed (&av->have_fastchunks, true);
4596	unsigned int idx = fastbin_index(size);
4597	fb = &fastbin (av, idx);
4598
4599	/ Atomically link P to its fastbin: P->FD = FB; FB = P; /
4600	mchunkptr old = *fb, old2;
4601
4602	if (SINGLE_THREAD_P)
4603	{
4604	/ Check that the top of the bin is not the record we are going to*
4605	add (i.e., double free). /*
4606	if (__builtin_expect (old == p, `0`))
4607	malloc_printerr (str: "double free or corruption (fasttop)");
4608	p->fd = PROTECT_PTR (&p->fd, old);
4609	*fb = p;
4610	}
4611	else
4612	do
4613	{
4614	/ Check that the top of the bin is not the record we are going to*
4615	add (i.e., double free). /*
4616	if (__builtin_expect (old == p, `0`))
4617	malloc_printerr (str: "double free or corruption (fasttop)");
4618	old2 = old;
4619	p->fd = PROTECT_PTR (&p->fd, old);
4620	}
4621	while ((old = catomic_compare_and_exchange_val_rel (fb, p, old2))
4622	!= old2);
4623
4624	/ Check that size of fastbin chunk at the top is the same as*
4625	size of the chunk that we are adding. We can dereference OLD
4626	only if we have the lock, otherwise it might have already been
4627	allocated again. /*
4628	if (have_lock && old != NULL
4629	&& __builtin_expect (fastbin_index (chunksize (old)) != idx, `0`))
4630	malloc_printerr (str: "invalid fastbin entry (free)");
4631	}
4632
4633	/*
4634	Consolidate other non-mmapped chunks as they arrive.
4635	*/
4636
4637	else if (!chunk_is_mmapped(p)) {
4638
4639	/ If we're single-threaded, don't lock the arena. /
4640	if (SINGLE_THREAD_P)
4641	have_lock = true;
4642
4643	if (!have_lock)
4644	__libc_lock_lock (av->mutex);
4645
4646	_int_free_merge_chunk (av, p, size);
4647
4648	if (!have_lock)
4649	__libc_lock_unlock (av->mutex);
4650	}
4651	/*
4652	If the chunk was allocated via mmap, release via munmap().
4653	*/
4654
4655	else {
4656	munmap_chunk (p);
4657	}
4658	}
4659
4660	/ Try to merge chunk P of SIZE bytes with its neighbors. Put the*
4661	resulting chunk on the appropriate bin list. P must not be on a
4662	bin list yet, and it can be in use. /*
4663	static void
4664	_int_free_merge_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T size)
4665	{
4666	mchunkptr nextchunk = chunk_at_offset(p, size);
4667
4668	/ Lightweight tests: check whether the block is already the*
4669	top block. /*
4670	if (__glibc_unlikely (p == av->top))
4671	malloc_printerr (str: "double free or corruption (top)");
4672	/ Or whether the next chunk is beyond the boundaries of the arena. /
4673	if (__builtin_expect (contiguous (av)
4674	&& (char *) nextchunk
4675	>= ((char *) av->top + chunksize(av->top)), `0`))
4676	malloc_printerr (str: "double free or corruption (out)");
4677	/ Or whether the block is actually not marked used. /
4678	if (__glibc_unlikely (!prev_inuse(nextchunk)))
4679	malloc_printerr (str: "double free or corruption (!prev)");
4680
4681	INTERNAL_SIZE_T nextsize = chunksize(nextchunk);
4682	if (__builtin_expect (chunksize_nomask (nextchunk) <= CHUNK_HDR_SZ, `0`)
4683	\|\| __builtin_expect (nextsize >= av->system_mem, `0`))
4684	malloc_printerr (str: "free(): invalid next size (normal)");
4685
4686	free_perturb (chunk2mem(p), n: size - CHUNK_HDR_SZ);
4687
4688	/ Consolidate backward. /
4689	if (!prev_inuse(p))
4690	{
4691	INTERNAL_SIZE_T prevsize = prev_size (p);
4692	size += prevsize;
4693	p = chunk_at_offset(p, -((long) prevsize));
4694	if (__glibc_unlikely (chunksize(p) != prevsize))
4695	malloc_printerr (str: "corrupted size vs. prev_size while consolidating");
4696	unlink_chunk (av, p);
4697	}
4698
4699	/ Write the chunk header, maybe after merging with the following chunk. /
4700	size = _int_free_create_chunk (av, p, size, nextchunk, nextsize);
4701	_int_free_maybe_consolidate (av, size);
4702	}
4703
4704	/ Create a chunk at P of SIZE bytes, with SIZE potentially increased*
4705	to cover the immediately following chunk NEXTCHUNK of NEXTSIZE
4706	bytes (if NEXTCHUNK is unused). The chunk at P is not actually
4707	read and does not have to be initialized. After creation, it is
4708	placed on the appropriate bin list. The function returns the size
4709	of the new chunk. /*
4710	static INTERNAL_SIZE_T
4711	_int_free_create_chunk (mstate av, mchunkptr p, INTERNAL_SIZE_T size,
4712	mchunkptr nextchunk, INTERNAL_SIZE_T nextsize)
4713	{
4714	if (nextchunk != av->top)
4715	{
4716	/ get and clear inuse bit /
4717	bool nextinuse = inuse_bit_at_offset (nextchunk, nextsize);
4718
4719	/ consolidate forward /
4720	if (!nextinuse) {
4721	unlink_chunk (av, p: nextchunk);
4722	size += nextsize;
4723	} else
4724	clear_inuse_bit_at_offset(nextchunk, `0`);
4725
4726	/*
4727	Place the chunk in unsorted chunk list. Chunks are
4728	not placed into regular bins until after they have
4729	been given one chance to be used in malloc.
4730	*/
4731
4732	mchunkptr bck = unsorted_chunks (av);
4733	mchunkptr fwd = bck->fd;
4734	if (__glibc_unlikely (fwd->bk != bck))
4735	malloc_printerr (str: "free(): corrupted unsorted chunks");
4736	p->fd = fwd;
4737	p->bk = bck;
4738	if (!in_smallbin_range(size))
4739	{
4740	p->fd_nextsize = NULL;
4741	p->bk_nextsize = NULL;
4742	}
4743	bck->fd = p;
4744	fwd->bk = p;
4745
4746	set_head(p, size \| PREV_INUSE);
4747	set_foot(p, size);
4748
4749	check_free_chunk(av, p);
4750	}
4751
4752	else
4753	{
4754	/ If the chunk borders the current high end of memory,*
4755	consolidate into top. /*
4756	size += nextsize;
4757	set_head(p, size \| PREV_INUSE);
4758	av->top = p;
4759	check_chunk(av, p);
4760	}
4761
4762	return size;
4763	}
4764
4765	/ If freeing a large space, consolidate possibly-surrounding*
4766	chunks. Then, if the total unused topmost memory exceeds trim
4767	threshold, ask malloc_trim to reduce top. /*
4768	static void
4769	_int_free_maybe_consolidate (mstate av, INTERNAL_SIZE_T size)
4770	{
4771	/ Unless max_fast is 0, we don't know if there are fastbins*
4772	bordering top, so we cannot tell for sure whether threshold has
4773	been reached unless fastbins are consolidated. But we don't want
4774	to consolidate on each free. As a compromise, consolidation is
4775	performed if FASTBIN_CONSOLIDATION_THRESHOLD is reached. /*
4776	if (size >= FASTBIN_CONSOLIDATION_THRESHOLD)
4777	{
4778	if (atomic_load_relaxed (&av->have_fastchunks))
4779	malloc_consolidate(av);
4780
4781	if (av == &main_arena)
4782	{
4783	#ifndef MORECORE_CANNOT_TRIM
4784	if (chunksize (av->top) >= mp_.trim_threshold)
4785	systrim (pad: mp_.top_pad, av);
4786	#endif
4787	}
4788	else
4789	{
4790	/ Always try heap_trim, even if the top chunk is not large,*
4791	because the corresponding heap might go away. /*
4792	heap_info *heap = heap_for_ptr (top (av));
4793
4794	assert (heap->ar_ptr == av);
4795	heap_trim (heap, pad: mp_.top_pad);
4796	}
4797	}
4798	}
4799
4800	/*
4801	------------------------- malloc_consolidate -------------------------
4802
4803	malloc_consolidate is a specialized version of free() that tears
4804	down chunks held in fastbins. Free itself cannot be used for this
4805	purpose since, among other things, it might place chunks back onto
4806	fastbins. So, instead, we need to use a minor variant of the same
4807	code.
4808	*/
4809
4810	static void malloc_consolidate(mstate av)
4811	{
4812	mfastbinptr* fb; / current fastbin being consolidated /
4813	mfastbinptr* maxfb; / last fastbin (for loop control) /
4814	mchunkptr p; / current chunk being consolidated /
4815	mchunkptr nextp; / next chunk to consolidate /
4816	mchunkptr unsorted_bin; / bin header /
4817	mchunkptr first_unsorted; / chunk to link to /
4818
4819	/ These have same use as in free() /
4820	mchunkptr nextchunk;
4821	INTERNAL_SIZE_T size;
4822	INTERNAL_SIZE_T nextsize;
4823	INTERNAL_SIZE_T prevsize;
4824	int nextinuse;
4825
4826	atomic_store_relaxed (&av->have_fastchunks, false);
4827
4828	unsorted_bin = unsorted_chunks(av);
4829
4830	/*
4831	Remove each chunk from fast bin and consolidate it, placing it
4832	then in unsorted bin. Among other reasons for doing this,
4833	placing in unsorted bin avoids needing to calculate actual bins
4834	until malloc is sure that chunks aren't immediately going to be
4835	reused anyway.
4836	*/
4837
4838	maxfb = &fastbin (av, NFASTBINS - `1`);
4839	fb = &fastbin (av, `0`);
4840	do {
4841	p = atomic_exchange_acquire (fb, NULL);
4842	if (p != `0`) {
4843	do {
4844	{
4845	if (__glibc_unlikely (misaligned_chunk (p)))
4846	malloc_printerr (str: "malloc_consolidate(): "
4847	"unaligned fastbin chunk detected");
4848
4849	unsigned int idx = fastbin_index (chunksize (p));
4850	if ((&fastbin (av, idx)) != fb)
4851	malloc_printerr (str: "malloc_consolidate(): invalid chunk size");
4852	}
4853
4854	check_inuse_chunk(av, p);
4855	nextp = REVEAL_PTR (p->fd);
4856
4857	/ Slightly streamlined version of consolidation code in free() /
4858	size = chunksize (p);
4859	nextchunk = chunk_at_offset(p, size);
4860	nextsize = chunksize(nextchunk);
4861
4862	if (!prev_inuse(p)) {
4863	prevsize = prev_size (p);
4864	size += prevsize;
4865	p = chunk_at_offset(p, -((long) prevsize));
4866	if (__glibc_unlikely (chunksize(p) != prevsize))
4867	malloc_printerr (str: "corrupted size vs. prev_size in fastbins");
4868	unlink_chunk (av, p);
4869	}
4870
4871	if (nextchunk != av->top) {
4872	nextinuse = inuse_bit_at_offset(nextchunk, nextsize);
4873
4874	if (!nextinuse) {
4875	size += nextsize;
4876	unlink_chunk (av, p: nextchunk);
4877	} else
4878	clear_inuse_bit_at_offset(nextchunk, `0`);
4879
4880	first_unsorted = unsorted_bin->fd;
4881	unsorted_bin->fd = p;
4882	first_unsorted->bk = p;
4883
4884	if (!in_smallbin_range (size)) {
4885	p->fd_nextsize = NULL;
4886	p->bk_nextsize = NULL;
4887	}
4888
4889	set_head(p, size \| PREV_INUSE);
4890	p->bk = unsorted_bin;
4891	p->fd = first_unsorted;
4892	set_foot(p, size);
4893	}
4894
4895	else {
4896	size += nextsize;
4897	set_head(p, size \| PREV_INUSE);
4898	av->top = p;
4899	}
4900
4901	} while ( (p = nextp) != `0`);
4902
4903	}
4904	} while (fb++ != maxfb);
4905	}
4906
4907	/*
4908	------------------------------ realloc ------------------------------
4909	*/
4910
4911	static void *
4912	_int_realloc (mstate av, mchunkptr oldp, INTERNAL_SIZE_T oldsize,
4913	INTERNAL_SIZE_T nb)
4914	{
4915	mchunkptr newp; / chunk to return /
4916	INTERNAL_SIZE_T newsize; / its size /
4917	void* newmem; / corresponding user mem /
4918
4919	mchunkptr next; / next contiguous chunk after oldp /
4920
4921	mchunkptr remainder; / extra space at end of newp /
4922	unsigned long remainder_size; / its size /
4923
4924	/ oldmem size /
4925	if (__builtin_expect (chunksize_nomask (oldp) <= CHUNK_HDR_SZ, `0`)
4926	\|\| __builtin_expect (oldsize >= av->system_mem, `0`)
4927	\|\| __builtin_expect (oldsize != chunksize (oldp), `0`))
4928	malloc_printerr (str: "realloc(): invalid old size");
4929
4930	check_inuse_chunk (av, oldp);
4931
4932	/ All callers already filter out mmap'ed chunks. /
4933	assert (!chunk_is_mmapped (oldp));
4934
4935	next = chunk_at_offset (oldp, oldsize);
4936	INTERNAL_SIZE_T nextsize = chunksize (next);
4937	if (__builtin_expect (chunksize_nomask (next) <= CHUNK_HDR_SZ, `0`)
4938	\|\| __builtin_expect (nextsize >= av->system_mem, `0`))
4939	malloc_printerr (str: "realloc(): invalid next size");
4940
4941	if ((unsigned long) (oldsize) >= (unsigned long) (nb))
4942	{
4943	/ already big enough; split below /
4944	newp = oldp;
4945	newsize = oldsize;
4946	}
4947
4948	else
4949	{
4950	/ Try to expand forward into top /
4951	if (next == av->top &&
4952	(unsigned long) (newsize = oldsize + nextsize) >=
4953	(unsigned long) (nb + MINSIZE))
4954	{
4955	set_head_size (oldp, nb \| (av != &main_arena ? NON_MAIN_ARENA : `0`));
4956	av->top = chunk_at_offset (oldp, nb);
4957	set_head (av->top, (newsize - nb) \| PREV_INUSE);
4958	check_inuse_chunk (av, oldp);
4959	return tag_new_usable (chunk2mem (oldp));
4960	}
4961
4962	/ Try to expand forward into next chunk; split off remainder below /
4963	else if (next != av->top &&
4964	!inuse (next) &&
4965	(unsigned long) (newsize = oldsize + nextsize) >=
4966	(unsigned long) (nb))
4967	{
4968	newp = oldp;
4969	unlink_chunk (av, p: next);
4970	}
4971
4972	/ allocate, copy, free /
4973	else
4974	{
4975	newmem = _int_malloc (av, bytes: nb - MALLOC_ALIGN_MASK);
4976	if (newmem == `0`)
4977	return `0`; / propagate failure /
4978
4979	newp = mem2chunk (newmem);
4980	newsize = chunksize (newp);
4981
4982	/*
4983	Avoid copy if newp is next chunk after oldp.
4984	*/
4985	if (newp == next)
4986	{
4987	newsize += oldsize;
4988	newp = oldp;
4989	}
4990	else
4991	{
4992	void *oldmem = chunk2mem (oldp);
4993	size_t sz = memsize (oldp);
4994	(void) tag_region (ptr: oldmem, size: sz);
4995	newmem = tag_new_usable (ptr: newmem);
4996	memcpy (dest: newmem, src: oldmem, n: sz);
4997	_int_free (av, p: oldp, have_lock: `1`);
4998	check_inuse_chunk (av, newp);
4999	return newmem;
5000	}
5001	}
5002	}
5003
5004	/ If possible, free extra space in old or extended chunk /
5005
5006	assert ((unsigned long) (newsize) >= (unsigned long) (nb));
5007
5008	remainder_size = newsize - nb;
5009
5010	if (remainder_size < MINSIZE) / not enough extra to split off /
5011	{
5012	set_head_size (newp, newsize \| (av != &main_arena ? NON_MAIN_ARENA : `0`));
5013	set_inuse_bit_at_offset (newp, newsize);
5014	}
5015	else / split remainder /
5016	{
5017	remainder = chunk_at_offset (newp, nb);
5018	/ Clear any user-space tags before writing the header. /
5019	remainder = tag_region (ptr: remainder, size: remainder_size);
5020	set_head_size (newp, nb \| (av != &main_arena ? NON_MAIN_ARENA : `0`));
5021	set_head (remainder, remainder_size \| PREV_INUSE \|
5022	(av != &main_arena ? NON_MAIN_ARENA : `0`));
5023	/ Mark remainder as inuse so free() won't complain /
5024	set_inuse_bit_at_offset (remainder, remainder_size);
5025	_int_free (av, p: remainder, have_lock: `1`);
5026	}
5027
5028	check_inuse_chunk (av, newp);
5029	return tag_new_usable (chunk2mem (newp));
5030	}
5031
5032	/*
5033	------------------------------ memalign ------------------------------
5034	*/
5035
5036	/ BYTES is user requested bytes, not requested chunksize bytes. /
5037	static void *
5038	_int_memalign (mstate av, size_t alignment, size_t bytes)
5039	{
5040	INTERNAL_SIZE_T nb; / padded request size /
5041	char m; /* memory returned by malloc call /
5042	mchunkptr p; / corresponding chunk /
5043	char brk; /* alignment point within p /
5044	mchunkptr newp; / chunk to return /
5045	INTERNAL_SIZE_T newsize; / its size /
5046	INTERNAL_SIZE_T leadsize; / leading space before alignment point /
5047	mchunkptr remainder; / spare room at end to split off /
5048	unsigned long remainder_size; / its size /
5049	INTERNAL_SIZE_T size;
5050
5051	nb = checked_request2size (req: bytes);
5052	if (nb == `0`)
5053	{
5054	__set_errno (ENOMEM);
5055	return NULL;
5056	}
5057
5058	/ We can't check tcache here because we hold the arena lock, which*
5059	tcache doesn't expect. We expect it has been checked
5060	earlier. /*
5061
5062	/ Strategy: search the bins looking for an existing block that*
5063	meets our needs. We scan a range of bins from "exact size" to
5064	"just under 2x", spanning the small/large barrier if needed. If
5065	we don't find anything in those bins, the common malloc code will
5066	scan starting at 2x. /*
5067
5068	/ Call malloc with worst case padding to hit alignment. /
5069	m = (char *) (_int_malloc (av, bytes: nb + alignment + MINSIZE));
5070
5071	if (m == `0`)
5072	return `0`; / propagate failure /
5073
5074	p = mem2chunk (m);
5075
5076	if ((((unsigned long) (m)) % alignment) != `0`) / misaligned /
5077	{
5078	/ Find an aligned spot inside chunk. Since we need to give back*
5079	leading space in a chunk of at least MINSIZE, if the first
5080	calculation places us at a spot with less than MINSIZE leader,
5081	we can move to the next aligned spot -- we've allocated enough
5082	total room so that this is always possible. /*
5083	brk = (char ) mem2chunk (((unsigned* long) (m + alignment - `1`)) &
5084	- ((signed long) alignment));
5085	if ((unsigned long) (brk - (char *) (p)) < MINSIZE)
5086	brk += alignment;
5087
5088	newp = (mchunkptr) brk;
5089	leadsize = brk - (char *) (p);
5090	newsize = chunksize (p) - leadsize;
5091
5092	/ For mmapped chunks, just adjust offset /
5093	if (chunk_is_mmapped (p))
5094	{
5095	set_prev_size (newp, prev_size (p) + leadsize);
5096	set_head (newp, newsize \| IS_MMAPPED);
5097	return chunk2mem (newp);
5098	}
5099
5100	/ Otherwise, give back leader, use the rest /
5101	set_head (newp, newsize \| PREV_INUSE \|
5102	(av != &main_arena ? NON_MAIN_ARENA : `0`));
5103	set_inuse_bit_at_offset (newp, newsize);
5104	set_head_size (p, leadsize \| (av != &main_arena ? NON_MAIN_ARENA : `0`));
5105	_int_free_merge_chunk (av, p, size: leadsize);
5106	p = newp;
5107
5108	assert (newsize >= nb &&
5109	(((unsigned long) (chunk2mem (p))) % alignment) == `0`);
5110	}
5111
5112	/ Also give back spare room at the end /
5113	if (!chunk_is_mmapped (p))
5114	{
5115	size = chunksize (p);
5116	mchunkptr nextchunk = chunk_at_offset(p, size);
5117	INTERNAL_SIZE_T nextsize = chunksize(nextchunk);
5118	if (size > nb)
5119	{
5120	remainder_size = size - nb;
5121	if (remainder_size >= MINSIZE
5122	\|\| nextchunk == av->top
5123	\|\| !inuse_bit_at_offset (nextchunk, nextsize))
5124	{
5125	/ We can only give back the tail if it is larger than*
5126	MINSIZE, or if the following chunk is unused (top
5127	chunk or unused in-heap chunk). Otherwise we would
5128	create a chunk that is smaller than MINSIZE. /*
5129	remainder = chunk_at_offset (p, nb);
5130	set_head_size (p, nb);
5131	remainder_size = _int_free_create_chunk (av, p: remainder,
5132	size: remainder_size,
5133	nextchunk, nextsize);
5134	_int_free_maybe_consolidate (av, size: remainder_size);
5135	}
5136	}
5137	}
5138
5139	check_inuse_chunk (av, p);
5140	return chunk2mem (p);
5141	}
5142
5143
5144	/*
5145	------------------------------ malloc_trim ------------------------------
5146	*/
5147
5148	static int
5149	mtrim (mstate av, size_t pad)
5150	{
5151	/ Ensure all blocks are consolidated. /
5152	malloc_consolidate (av);
5153
5154	const size_t ps = GLRO (dl_pagesize);
5155	int psindex = bin_index (ps);
5156	const size_t psm1 = ps - `1`;
5157
5158	int result = `0`;
5159	for (int i = `1`; i < NBINS; ++i)
5160	if (i == `1` \|\| i >= psindex)
5161	{
5162	mbinptr bin = bin_at (av, i);
5163
5164	for (mchunkptr p = last (bin); p != bin; p = p->bk)
5165	{
5166	INTERNAL_SIZE_T size = chunksize (p);
5167
5168	if (size > psm1 + sizeof (struct malloc_chunk))
5169	{
5170	/ See whether the chunk contains at least one unused page. /
5171	char paligned_mem = (char* *) (((uintptr_t) p
5172	+ sizeof (struct malloc_chunk)
5173	+ psm1) & ~psm1);
5174
5175	assert ((char ) chunk2mem (p) + `2` CHUNK_HDR_SZ
5176	<= paligned_mem);
5177	assert ((char *) p + size > paligned_mem);
5178
5179	/ This is the size we could potentially free. /
5180	size -= paligned_mem - (char *) p;
5181
5182	if (size > psm1)
5183	{
5184	#if MALLOC_DEBUG
5185	/ When debugging we simulate destroying the memory*
5186	content. /*
5187	memset (paligned_mem, `0x89`, size & ~psm1);
5188	#endif
5189	__madvise (addr: paligned_mem, len: size & ~psm1, MADV_DONTNEED);
5190
5191	result = `1`;
5192	}
5193	}
5194	}
5195	}
5196
5197	#ifndef MORECORE_CANNOT_TRIM
5198	return result \| (av == &main_arena ? systrim (pad, av) : `0`);
5199
5200	#else
5201	return result;
5202	#endif
5203	}
5204
5205
5206	int
5207	__malloc_trim (size_t s)
5208	{
5209	int result = `0`;
5210
5211	if (!__malloc_initialized)
5212	ptmalloc_init ();
5213
5214	mstate ar_ptr = &main_arena;
5215	do
5216	{
5217	__libc_lock_lock (ar_ptr->mutex);
5218	result \|= mtrim (av: ar_ptr, pad: s);
5219	__libc_lock_unlock (ar_ptr->mutex);
5220
5221	ar_ptr = ar_ptr->next;
5222	}
5223	while (ar_ptr != &main_arena);
5224
5225	return result;
5226	}
5227
5228
5229	/*
5230	------------------------- malloc_usable_size -------------------------
5231	*/
5232
5233	static size_t
5234	musable (void *mem)
5235	{
5236	mchunkptr p = mem2chunk (mem);
5237
5238	if (chunk_is_mmapped (p))
5239	return chunksize (p) - CHUNK_HDR_SZ;
5240	else if (inuse (p))
5241	return memsize (p);
5242
5243	return `0`;
5244	}
5245
5246	#if IS_IN (libc)
5247	size_t
5248	__malloc_usable_size (void *m)
5249	{
5250	if (m == NULL)
5251	return `0`;
5252	return musable (m);
5253	}
5254	#endif
5255
5256	/*
5257	------------------------------ mallinfo ------------------------------
5258	Accumulate malloc statistics for arena AV into M.
5259	*/
5260	static void
5261	int_mallinfo (mstate av, struct mallinfo2 *m)
5262	{
5263	size_t i;
5264	mbinptr b;
5265	mchunkptr p;
5266	INTERNAL_SIZE_T avail;
5267	INTERNAL_SIZE_T fastavail;
5268	int nblocks;
5269	int nfastblocks;
5270
5271	check_malloc_state (av);
5272
5273	/ Account for top /
5274	avail = chunksize (av->top);
5275	nblocks = `1`; / top always exists /
5276
5277	/ traverse fastbins /
5278	nfastblocks = `0`;
5279	fastavail = `0`;
5280
5281	for (i = `0`; i < NFASTBINS; ++i)
5282	{
5283	for (p = fastbin (av, i);
5284	p != `0`;
5285	p = REVEAL_PTR (p->fd))
5286	{
5287	if (__glibc_unlikely (misaligned_chunk (p)))
5288	malloc_printerr (str: "int_mallinfo(): "
5289	"unaligned fastbin chunk detected");
5290	++nfastblocks;
5291	fastavail += chunksize (p);
5292	}
5293	}
5294
5295	avail += fastavail;
5296
5297	/ traverse regular bins /
5298	for (i = `1`; i < NBINS; ++i)
5299	{
5300	b = bin_at (av, i);
5301	for (p = last (b); p != b; p = p->bk)
5302	{
5303	++nblocks;
5304	avail += chunksize (p);
5305	}
5306	}
5307
5308	m->smblks += nfastblocks;
5309	m->ordblks += nblocks;
5310	m->fordblks += avail;
5311	m->uordblks += av->system_mem - avail;
5312	m->arena += av->system_mem;
5313	m->fsmblks += fastavail;
5314	if (av == &main_arena)
5315	{
5316	m->hblks = mp_.n_mmaps;
5317	m->hblkhd = mp_.mmapped_mem;
5318	m->usmblks = `0`;
5319	m->keepcost = chunksize (av->top);
5320	}
5321	}
5322
5323
5324	struct mallinfo2
5325	__libc_mallinfo2 (void)
5326	{
5327	struct mallinfo2 m;
5328	mstate ar_ptr;
5329
5330	if (!__malloc_initialized)
5331	ptmalloc_init ();
5332
5333	memset (s: &m, c: `0`, n: sizeof (m));
5334	ar_ptr = &main_arena;
5335	do
5336	{
5337	__libc_lock_lock (ar_ptr->mutex);
5338	int_mallinfo (av: ar_ptr, m: &m);
5339	__libc_lock_unlock (ar_ptr->mutex);
5340
5341	ar_ptr = ar_ptr->next;
5342	}
5343	while (ar_ptr != &main_arena);
5344
5345	return m;
5346	}
5347	libc_hidden_def (__libc_mallinfo2)
5348
5349	struct mallinfo
5350	__libc_mallinfo (void)
5351	{
5352	struct mallinfo m;
5353	struct mallinfo2 m2 = __libc_mallinfo2 ();
5354
5355	m.arena = m2.arena;
5356	m.ordblks = m2.ordblks;
5357	m.smblks = m2.smblks;
5358	m.hblks = m2.hblks;
5359	m.hblkhd = m2.hblkhd;
5360	m.usmblks = m2.usmblks;
5361	m.fsmblks = m2.fsmblks;
5362	m.uordblks = m2.uordblks;
5363	m.fordblks = m2.fordblks;
5364	m.keepcost = m2.keepcost;
5365
5366	return m;
5367	}
5368
5369
5370	/*
5371	------------------------------ malloc_stats ------------------------------
5372	*/
5373
5374	void
5375	__malloc_stats (void)
5376	{
5377	int i;
5378	mstate ar_ptr;
5379	unsigned int in_use_b = mp_.mmapped_mem, system_b = in_use_b;
5380
5381	if (!__malloc_initialized)
5382	ptmalloc_init ();
5383	_IO_flockfile (stderr);
5384	int old_flags2 = stderr->_flags2;
5385	stderr->_flags2 \|= _IO_FLAGS2_NOTCANCEL;
5386	for (i = `0`, ar_ptr = &main_arena;; i++)
5387	{
5388	struct mallinfo2 mi;
5389
5390	memset (s: &mi, c: `0`, n: sizeof (mi));
5391	__libc_lock_lock (ar_ptr->mutex);
5392	int_mallinfo (av: ar_ptr, m: &mi);
5393	fprintf (stderr, format: "Arena %d:\n", i);
5394	fprintf (stderr, format: "system bytes = %10u\n", (unsigned int) mi.arena);
5395	fprintf (stderr, format: "in use bytes = %10u\n", (unsigned int) mi.uordblks);
5396	#if MALLOC_DEBUG > 1
5397	if (i > `0`)
5398	dump_heap (heap_for_ptr (top (ar_ptr)));
5399	#endif
5400	system_b += mi.arena;
5401	in_use_b += mi.uordblks;
5402	__libc_lock_unlock (ar_ptr->mutex);
5403	ar_ptr = ar_ptr->next;
5404	if (ar_ptr == &main_arena)
5405	break;
5406	}
5407	fprintf (stderr, format: "Total (incl. mmap):\n");
5408	fprintf (stderr, format: "system bytes = %10u\n", system_b);
5409	fprintf (stderr, format: "in use bytes = %10u\n", in_use_b);
5410	fprintf (stderr, format: "max mmap regions = %10u\n", (unsigned int) mp_.max_n_mmaps);
5411	fprintf (stderr, format: "max mmap bytes = %10lu\n",
5412	(unsigned long) mp_.max_mmapped_mem);
5413	stderr->_flags2 = old_flags2;
5414	_IO_funlockfile (stderr);
5415	}
5416
5417
5418	/*
5419	------------------------------ mallopt ------------------------------
5420	*/
5421	static __always_inline int
5422	do_set_trim_threshold (size_t value)
5423	{
5424	LIBC_PROBE (memory_mallopt_trim_threshold, `3`, value, mp_.trim_threshold,
5425	mp_.no_dyn_threshold);
5426	mp_.trim_threshold = value;
5427	mp_.no_dyn_threshold = `1`;
5428	return `1`;
5429	}
5430
5431	static __always_inline int
5432	do_set_top_pad (size_t value)
5433	{
5434	LIBC_PROBE (memory_mallopt_top_pad, `3`, value, mp_.top_pad,
5435	mp_.no_dyn_threshold);
5436	mp_.top_pad = value;
5437	mp_.no_dyn_threshold = `1`;
5438	return `1`;
5439	}
5440
5441	static __always_inline int
5442	do_set_mmap_threshold (size_t value)
5443	{
5444	LIBC_PROBE (memory_mallopt_mmap_threshold, `3`, value, mp_.mmap_threshold,
5445	mp_.no_dyn_threshold);
5446	mp_.mmap_threshold = value;
5447	mp_.no_dyn_threshold = `1`;
5448	return `1`;
5449	}
5450
5451	static __always_inline int
5452	do_set_mmaps_max (int32_t value)
5453	{
5454	LIBC_PROBE (memory_mallopt_mmap_max, `3`, value, mp_.n_mmaps_max,
5455	mp_.no_dyn_threshold);
5456	mp_.n_mmaps_max = value;
5457	mp_.no_dyn_threshold = `1`;
5458	return `1`;
5459	}
5460
5461	static __always_inline int
5462	do_set_mallopt_check (int32_t value)
5463	{
5464	return `1`;
5465	}
5466
5467	static __always_inline int
5468	do_set_perturb_byte (int32_t value)
5469	{
5470	LIBC_PROBE (memory_mallopt_perturb, `2`, value, perturb_byte);
5471	perturb_byte = value;
5472	return `1`;
5473	}
5474
5475	static __always_inline int
5476	do_set_arena_test (size_t value)
5477	{
5478	LIBC_PROBE (memory_mallopt_arena_test, `2`, value, mp_.arena_test);
5479	mp_.arena_test = value;
5480	return `1`;
5481	}
5482
5483	static __always_inline int
5484	do_set_arena_max (size_t value)
5485	{
5486	LIBC_PROBE (memory_mallopt_arena_max, `2`, value, mp_.arena_max);
5487	mp_.arena_max = value;
5488	return `1`;
5489	}
5490
5491	#if USE_TCACHE
5492	static __always_inline int
5493	do_set_tcache_max (size_t value)
5494	{
5495	if (value <= MAX_TCACHE_SIZE)
5496	{
5497	LIBC_PROBE (memory_tunable_tcache_max_bytes, `2`, value, mp_.tcache_max_bytes);
5498	mp_.tcache_max_bytes = value;
5499	mp_.tcache_bins = csize2tidx (request2size(value)) + `1`;
5500	return `1`;
5501	}
5502	return `0`;
5503	}
5504
5505	static __always_inline int
5506	do_set_tcache_count (size_t value)
5507	{
5508	if (value <= MAX_TCACHE_COUNT)
5509	{
5510	LIBC_PROBE (memory_tunable_tcache_count, `2`, value, mp_.tcache_count);
5511	mp_.tcache_count = value;
5512	return `1`;
5513	}
5514	return `0`;
5515	}
5516
5517	static __always_inline int
5518	do_set_tcache_unsorted_limit (size_t value)
5519	{
5520	LIBC_PROBE (memory_tunable_tcache_unsorted_limit, `2`, value, mp_.tcache_unsorted_limit);
5521	mp_.tcache_unsorted_limit = value;
5522	return `1`;
5523	}
5524	#endif
5525
5526	static __always_inline int
5527	do_set_mxfast (size_t value)
5528	{
5529	if (value <= MAX_FAST_SIZE)
5530	{
5531	LIBC_PROBE (memory_mallopt_mxfast, `2`, value, get_max_fast ());
5532	set_max_fast (value);
5533	return `1`;
5534	}
5535	return `0`;
5536	}
5537
5538	static __always_inline int
5539	do_set_hugetlb (size_t value)
5540	{
5541	if (value == `1`)
5542	{
5543	enum malloc_thp_mode_t thp_mode = __malloc_thp_mode ();
5544	/*
5545	Only enable THP madvise usage if system does support it and
5546	has 'madvise' mode. Otherwise the madvise() call is wasteful.
5547	*/
5548	if (thp_mode == malloc_thp_mode_madvise)
5549	mp_.thp_pagesize = __malloc_default_thp_pagesize ();
5550	}
5551	else if (value >= `2`)
5552	__malloc_hugepage_config (requested: value == `2` ? `0` : value, pagesize: &mp_.hp_pagesize,
5553	flags: &mp_.hp_flags);
5554	return `0`;
5555	}
5556
5557	int
5558	__libc_mallopt (int param_number, int value)
5559	{
5560	mstate av = &main_arena;
5561	int res = `1`;
5562
5563	if (!__malloc_initialized)
5564	ptmalloc_init ();
5565	__libc_lock_lock (av->mutex);
5566
5567	LIBC_PROBE (memory_mallopt, `2`, param_number, value);
5568
5569	/ We must consolidate main arena before changing max_fast*
5570	(see definition of set_max_fast). /*
5571	malloc_consolidate (av);
5572
5573	/ Many of these helper functions take a size_t. We do not worry*
5574	about overflow here, because negative int values will wrap to
5575	very large size_t values and the helpers have sufficient range
5576	checking for such conversions. Many of these helpers are also
5577	used by the tunables macros in arena.c. /*
5578
5579	switch (param_number)
5580	{
5581	case M_MXFAST:
5582	res = do_set_mxfast (value);
5583	break;
5584
5585	case M_TRIM_THRESHOLD:
5586	res = do_set_trim_threshold (value);
5587	break;
5588
5589	case M_TOP_PAD:
5590	res = do_set_top_pad (value);
5591	break;
5592
5593	case M_MMAP_THRESHOLD:
5594	res = do_set_mmap_threshold (value);
5595	break;
5596
5597	case M_MMAP_MAX:
5598	res = do_set_mmaps_max (value);
5599	break;
5600
5601	case M_CHECK_ACTION:
5602	res = do_set_mallopt_check (value);
5603	break;
5604
5605	case M_PERTURB:
5606	res = do_set_perturb_byte (value);
5607	break;
5608
5609	case M_ARENA_TEST:
5610	if (value > `0`)
5611	res = do_set_arena_test (value);
5612	break;
5613
5614	case M_ARENA_MAX:
5615	if (value > `0`)
5616	res = do_set_arena_max (value);
5617	break;
5618	}
5619	__libc_lock_unlock (av->mutex);
5620	return res;
5621	}
5622	libc_hidden_def (__libc_mallopt)
5623
5624
5625	/*
5626	-------------------- Alternative MORECORE functions --------------------
5627	*/
5628
5629
5630	/*
5631	General Requirements for MORECORE.
5632
5633	The MORECORE function must have the following properties:
5634
5635	If MORECORE_CONTIGUOUS is false:
5636
5637	* MORECORE must allocate in multiples of pagesize. It will
5638	only be called with arguments that are multiples of pagesize.
5639
5640	* MORECORE(0) must return an address that is at least
5641	MALLOC_ALIGNMENT aligned. (Page-aligning always suffices.)
5642
5643	else (i.e. If MORECORE_CONTIGUOUS is true):
5644
5645	* Consecutive calls to MORECORE with positive arguments
5646	return increasing addresses, indicating that space has been
5647	contiguously extended.
5648
5649	* MORECORE need not allocate in multiples of pagesize.
5650	Calls to MORECORE need not have args of multiples of pagesize.
5651
5652	* MORECORE need not page-align.
5653
5654	In either case:
5655
5656	* MORECORE may allocate more memory than requested. (Or even less,
5657	but this will generally result in a malloc failure.)
5658
5659	* MORECORE must not allocate memory when given argument zero, but
5660	instead return one past the end address of memory from previous
5661	nonzero call. This malloc does NOT call MORECORE(0)
5662	until at least one call with positive arguments is made, so
5663	the initial value returned is not important.
5664
5665	* Even though consecutive calls to MORECORE need not return contiguous
5666	addresses, it must be OK for malloc'ed chunks to span multiple
5667	regions in those cases where they do happen to be contiguous.
5668
5669	* MORECORE need not handle negative arguments -- it may instead
5670	just return MORECORE_FAILURE when given negative arguments.
5671	Negative arguments are always multiples of pagesize. MORECORE
5672	must not misinterpret negative args as large positive unsigned
5673	args. You can suppress all such calls from even occurring by defining
5674	MORECORE_CANNOT_TRIM,
5675
5676	There is some variation across systems about the type of the
5677	argument to sbrk/MORECORE. If size_t is unsigned, then it cannot
5678	actually be size_t, because sbrk supports negative args, so it is
5679	normally the signed type of the same width as size_t (sometimes
5680	declared as "intptr_t", and sometimes "ptrdiff_t"). It doesn't much
5681	matter though. Internally, we use "long" as arguments, which should
5682	work across all reasonable possibilities.
5683
5684	Additionally, if MORECORE ever returns failure for a positive
5685	request, then mmap is used as a noncontiguous system allocator. This
5686	is a useful backup strategy for systems with holes in address spaces
5687	-- in this case sbrk cannot contiguously expand the heap, but mmap
5688	may be able to map noncontiguous space.
5689
5690	If you'd like mmap to ALWAYS be used, you can define MORECORE to be
5691	a function that always returns MORECORE_FAILURE.
5692
5693	If you are using this malloc with something other than sbrk (or its
5694	emulation) to supply memory regions, you probably want to set
5695	MORECORE_CONTIGUOUS as false. As an example, here is a custom
5696	allocator kindly contributed for pre-OSX macOS. It uses virtually
5697	but not necessarily physically contiguous non-paged memory (locked
5698	in, present and won't get swapped out). You can use it by
5699	uncommenting this section, adding some #includes, and setting up the
5700	appropriate defines above:
5701
5702	*#define MORECORE osMoreCore
5703	*#define MORECORE_CONTIGUOUS 0
5704
5705	There is also a shutdown routine that should somehow be called for
5706	cleanup upon program exit.
5707
5708	*#define MAX_POOL_ENTRIES 100
5709	#define MINIMUM_MORECORE_SIZE (64 1024)
5710	static int next_os_pool;
5711	void our_os_pools[MAX_POOL_ENTRIES];*
5712
5713	void osMoreCore(int size)*
5714	{
5715	void ptr = 0;*
5716	static void sbrk_top = 0;*
5717
5718	if (size > 0)
5719	{
5720	if (size < MINIMUM_MORECORE_SIZE)
5721	size = MINIMUM_MORECORE_SIZE;
5722	if (CurrentExecutionLevel() == kTaskLevel)
5723	ptr = PoolAllocateResident(size + RM_PAGE_SIZE, 0);
5724	if (ptr == 0)
5725	{
5726	return (void ) MORECORE_FAILURE;*
5727	}
5728	// save ptrs so they can be freed during cleanup
5729	our_os_pools[next_os_pool] = ptr;
5730	next_os_pool++;
5731	ptr = (void ) ((((unsigned long) ptr) + RM_PAGE_MASK) & ~RM_PAGE_MASK);*
5732	sbrk_top = (char ) ptr + size;*
5733	return ptr;
5734	}
5735	else if (size < 0)
5736	{
5737	// we don't currently support shrink behavior
5738	return (void ) MORECORE_FAILURE;*
5739	}
5740	else
5741	{
5742	return sbrk_top;
5743	}
5744	}
5745
5746	// cleanup any allocated memory pools
5747	// called as last thing before shutting down driver
5748
5749	void osCleanupMem(void)
5750	{
5751	void ptr;
5752
5753	for (ptr = our_os_pools; ptr < &our_os_pools[MAX_POOL_ENTRIES]; ptr++)
5754	if (ptr)*
5755	{
5756	PoolDeallocate(ptr);*
5757	* ptr = 0;
5758	}
5759	}
5760
5761	*/
5762
5763
5764	/ Helper code. /
5765
5766	extern char **__libc_argv attribute_hidden;
5767
5768	static void
5769	malloc_printerr (const char *str)
5770	{
5771	#if IS_IN (libc)
5772	__libc_message ("%s\n", str);
5773	#else
5774	__libc_fatal (message: str);
5775	#endif
5776	__builtin_unreachable ();
5777	}
5778
5779	#if IS_IN (libc)
5780	/ We need a wrapper function for one of the additions of POSIX. /
5781	int
5782	__posix_memalign (void **memptr, size_t alignment, size_t size)
5783	{
5784	void *mem;
5785
5786	if (!__malloc_initialized)
5787	ptmalloc_init ();
5788
5789	/ Test whether the SIZE argument is valid. It must be a power of*
5790	two multiple of sizeof (void ). /
5791	if (alignment % sizeof (void *) != `0`
5792	\|\| !powerof2 (alignment / sizeof (void *))
5793	\|\| alignment == `0`)
5794	return EINVAL;
5795
5796
5797	void *address = RETURN_ADDRESS (`0`);
5798	mem = _mid_memalign (alignment, size, address);
5799
5800	if (mem != NULL)
5801	{
5802	*memptr = mem;
5803	return `0`;
5804	}
5805
5806	return ENOMEM;
5807	}
5808	weak_alias (__posix_memalign, posix_memalign)
5809	#endif
5810
5811
5812	int
5813	__malloc_info (int options, FILE *fp)
5814	{
5815	/ For now, at least. /
5816	if (options != `0`)
5817	return EINVAL;
5818
5819	int n = `0`;
5820	size_t total_nblocks = `0`;
5821	size_t total_nfastblocks = `0`;
5822	size_t total_avail = `0`;
5823	size_t total_fastavail = `0`;
5824	size_t total_system = `0`;
5825	size_t total_max_system = `0`;
5826	size_t total_aspace = `0`;
5827	size_t total_aspace_mprotect = `0`;
5828
5829
5830
5831	if (!__malloc_initialized)
5832	ptmalloc_init ();
5833
5834	fputs (s: "<malloc version=\"1\">\n", stream: fp);
5835
5836	/ Iterate over all arenas currently in use. /
5837	mstate ar_ptr = &main_arena;
5838	do
5839	{
5840	fprintf (stream: fp, format: "<heap nr=\"%d\">\n<sizes>\n", n++);
5841
5842	size_t nblocks = `0`;
5843	size_t nfastblocks = `0`;
5844	size_t avail = `0`;
5845	size_t fastavail = `0`;
5846	struct
5847	{
5848	size_t from;
5849	size_t to;
5850	size_t total;
5851	size_t count;
5852	} sizes[NFASTBINS + NBINS - `1`];
5853	#define nsizes (sizeof (sizes) / sizeof (sizes[0]))
5854
5855	__libc_lock_lock (ar_ptr->mutex);
5856
5857	/ Account for top chunk. The top-most available chunk is*
5858	treated specially and is never in any bin. See "initial_top"
5859	comments. /*
5860	avail = chunksize (ar_ptr->top);
5861	nblocks = `1`; / Top always exists. /
5862
5863	for (size_t i = `0`; i < NFASTBINS; ++i)
5864	{
5865	mchunkptr p = fastbin (ar_ptr, i);
5866	if (p != NULL)
5867	{
5868	size_t nthissize = `0`;
5869	size_t thissize = chunksize (p);
5870
5871	while (p != NULL)
5872	{
5873	if (__glibc_unlikely (misaligned_chunk (p)))
5874	malloc_printerr (str: "__malloc_info(): "
5875	"unaligned fastbin chunk detected");
5876	++nthissize;
5877	p = REVEAL_PTR (p->fd);
5878	}
5879
5880	fastavail += nthissize * thissize;
5881	nfastblocks += nthissize;
5882	sizes[i].from = thissize - (MALLOC_ALIGNMENT - `1`);
5883	sizes[i].to = thissize;
5884	sizes[i].count = nthissize;
5885	}
5886	else
5887	sizes[i].from = sizes[i].to = sizes[i].count = `0`;
5888
5889	sizes[i].total = sizes[i].count * sizes[i].to;
5890	}
5891
5892
5893	mbinptr bin;
5894	struct malloc_chunk *r;
5895
5896	for (size_t i = `1`; i < NBINS; ++i)
5897	{
5898	bin = bin_at (ar_ptr, i);
5899	r = bin->fd;
5900	sizes[NFASTBINS - `1` + i].from = ~((size_t) `0`);
5901	sizes[NFASTBINS - `1` + i].to = sizes[NFASTBINS - `1` + i].total
5902	= sizes[NFASTBINS - `1` + i].count = `0`;
5903
5904	if (r != NULL)
5905	while (r != bin)
5906	{
5907	size_t r_size = chunksize_nomask (r);
5908	++sizes[NFASTBINS - `1` + i].count;
5909	sizes[NFASTBINS - `1` + i].total += r_size;
5910	sizes[NFASTBINS - `1` + i].from
5911	= MIN (sizes[NFASTBINS - `1` + i].from, r_size);
5912	sizes[NFASTBINS - `1` + i].to = MAX (sizes[NFASTBINS - `1` + i].to,
5913	r_size);
5914
5915	r = r->fd;
5916	}
5917
5918	if (sizes[NFASTBINS - `1` + i].count == `0`)
5919	sizes[NFASTBINS - `1` + i].from = `0`;
5920	nblocks += sizes[NFASTBINS - `1` + i].count;
5921	avail += sizes[NFASTBINS - `1` + i].total;
5922	}
5923
5924	size_t heap_size = `0`;
5925	size_t heap_mprotect_size = `0`;
5926	size_t heap_count = `0`;
5927	if (ar_ptr != &main_arena)
5928	{
5929	/ Iterate over the arena heaps from back to front. /
5930	heap_info *heap = heap_for_ptr (top (ar_ptr));
5931	do
5932	{
5933	heap_size += heap->size;
5934	heap_mprotect_size += heap->mprotect_size;
5935	heap = heap->prev;
5936	++heap_count;
5937	}
5938	while (heap != NULL);
5939	}
5940
5941	__libc_lock_unlock (ar_ptr->mutex);
5942
5943	total_nfastblocks += nfastblocks;
5944	total_fastavail += fastavail;
5945
5946	total_nblocks += nblocks;
5947	total_avail += avail;
5948
5949	for (size_t i = `0`; i < nsizes; ++i)
5950	if (sizes[i].count != `0` && i != NFASTBINS)
5951	fprintf (stream: fp, format: "\
5952	<size from=\"%zu\" to=\"%zu\" total=\"%zu\" count=\"%zu\"/>\n",
5953	sizes[i].from, sizes[i].to, sizes[i].total, sizes[i].count);
5954
5955	if (sizes[NFASTBINS].count != `0`)
5956	fprintf (stream: fp, format: "\
5957	<unsorted from=\"%zu\" to=\"%zu\" total=\"%zu\" count=\"%zu\"/>\n",
5958	sizes[NFASTBINS].from, sizes[NFASTBINS].to,
5959	sizes[NFASTBINS].total, sizes[NFASTBINS].count);
5960
5961	total_system += ar_ptr->system_mem;
5962	total_max_system += ar_ptr->max_system_mem;
5963
5964	fprintf (stream: fp,
5965	format: "</sizes>\n<total type=\"fast\" count=\"%zu\" size=\"%zu\"/>\n"
5966	"<total type=\"rest\" count=\"%zu\" size=\"%zu\"/>\n"
5967	"<system type=\"current\" size=\"%zu\"/>\n"
5968	"<system type=\"max\" size=\"%zu\"/>\n",
5969	nfastblocks, fastavail, nblocks, avail,
5970	ar_ptr->system_mem, ar_ptr->max_system_mem);
5971
5972	if (ar_ptr != &main_arena)
5973	{
5974	fprintf (stream: fp,
5975	format: "<aspace type=\"total\" size=\"%zu\"/>\n"
5976	"<aspace type=\"mprotect\" size=\"%zu\"/>\n"
5977	"<aspace type=\"subheaps\" size=\"%zu\"/>\n",
5978	heap_size, heap_mprotect_size, heap_count);
5979	total_aspace += heap_size;
5980	total_aspace_mprotect += heap_mprotect_size;
5981	}
5982	else
5983	{
5984	fprintf (stream: fp,
5985	format: "<aspace type=\"total\" size=\"%zu\"/>\n"
5986	"<aspace type=\"mprotect\" size=\"%zu\"/>\n",
5987	ar_ptr->system_mem, ar_ptr->system_mem);
5988	total_aspace += ar_ptr->system_mem;
5989	total_aspace_mprotect += ar_ptr->system_mem;
5990	}
5991
5992	fputs (s: "</heap>\n", stream: fp);
5993	ar_ptr = ar_ptr->next;
5994	}
5995	while (ar_ptr != &main_arena);
5996
5997	fprintf (stream: fp,
5998	format: "<total type=\"fast\" count=\"%zu\" size=\"%zu\"/>\n"
5999	"<total type=\"rest\" count=\"%zu\" size=\"%zu\"/>\n"
6000	"<total type=\"mmap\" count=\"%d\" size=\"%zu\"/>\n"
6001	"<system type=\"current\" size=\"%zu\"/>\n"
6002	"<system type=\"max\" size=\"%zu\"/>\n"
6003	"<aspace type=\"total\" size=\"%zu\"/>\n"
6004	"<aspace type=\"mprotect\" size=\"%zu\"/>\n"
6005	"</malloc>\n",
6006	total_nfastblocks, total_fastavail, total_nblocks, total_avail,
6007	mp_.n_mmaps, mp_.mmapped_mem,
6008	total_system, total_max_system,
6009	total_aspace, total_aspace_mprotect);
6010
6011	return `0`;
6012	}
6013	#if IS_IN (libc)
6014	weak_alias (__malloc_info, malloc_info)
6015
6016	strong_alias (__libc_calloc, __calloc) weak_alias (__libc_calloc, calloc)
6017	strong_alias (__libc_free, __free) strong_alias (__libc_free, free)
6018	strong_alias (__libc_malloc, __malloc) strong_alias (__libc_malloc, malloc)
6019	strong_alias (__libc_memalign, __memalign)
6020	weak_alias (__libc_memalign, memalign)
6021	strong_alias (__libc_realloc, __realloc) strong_alias (__libc_realloc, realloc)
6022	strong_alias (__libc_valloc, __valloc) weak_alias (__libc_valloc, valloc)
6023	strong_alias (__libc_pvalloc, __pvalloc) weak_alias (__libc_pvalloc, pvalloc)
6024	strong_alias (__libc_mallinfo, __mallinfo)
6025	weak_alias (__libc_mallinfo, mallinfo)
6026	strong_alias (__libc_mallinfo2, __mallinfo2)
6027	weak_alias (__libc_mallinfo2, mallinfo2)
6028	strong_alias (__libc_mallopt, __mallopt) weak_alias (__libc_mallopt, mallopt)
6029
6030	weak_alias (__malloc_stats, malloc_stats)
6031	weak_alias (__malloc_usable_size, malloc_usable_size)
6032	weak_alias (__malloc_trim, malloc_trim)
6033	#endif
6034
6035	#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_26)
6036	compat_symbol (libc, __libc_free, cfree, GLIBC_2_0);
6037	#endif
6038
6039	/ ------------------------------------------------------------*
6040	History:
6041
6042	[see ftp://g.oswego.edu/pub/misc/malloc.c for the history of dlmalloc]
6043
6044	*/
6045	/*
6046	* Local variables:
6047	* c-basic-offset: 2
6048	* End:
6049	*/
6050

source code of glibc/malloc/malloc.c