* sysdeps/unix/sysv/linux/sysconf.c (__sysconf):
[glibc.git] / malloc / malloc.c
blob12e23b0f9b0cd00a989c7e0e9b65d919b6d82df4
1 /* Malloc implementation for multiple threads without lock contention.
2 Copyright (C) 1996-2006, 2007, 2008, 2009 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Wolfram Gloger <wg@malloc.de>
5 and Doug Lea <dl@cs.oswego.edu>, 2001.
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public License as
9 published by the Free Software Foundation; either version 2.1 of the
10 License, or (at your option) any later version.
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; see the file COPYING.LIB. If not,
19 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
23 This is a version (aka ptmalloc2) of malloc/free/realloc written by
24 Doug Lea and adapted to multiple threads/arenas by Wolfram Gloger.
26 * Version ptmalloc2-20011215
27 based on:
28 VERSION 2.7.0 Sun Mar 11 14:14:06 2001 Doug Lea (dl at gee)
30 * Quickstart
32 In order to compile this implementation, a Makefile is provided with
33 the ptmalloc2 distribution, which has pre-defined targets for some
34 popular systems (e.g. "make posix" for Posix threads). All that is
35 typically required with regard to compiler flags is the selection of
36 the thread package via defining one out of USE_PTHREADS, USE_THR or
37 USE_SPROC. Check the thread-m.h file for what effects this has.
38 Many/most systems will additionally require USE_TSD_DATA_HACK to be
39 defined, so this is the default for "make posix".
41 * Why use this malloc?
43 This is not the fastest, most space-conserving, most portable, or
44 most tunable malloc ever written. However it is among the fastest
45 while also being among the most space-conserving, portable and tunable.
46 Consistent balance across these factors results in a good general-purpose
47 allocator for malloc-intensive programs.
49 The main properties of the algorithms are:
50 * For large (>= 512 bytes) requests, it is a pure best-fit allocator,
51 with ties normally decided via FIFO (i.e. least recently used).
52 * For small (<= 64 bytes by default) requests, it is a caching
53 allocator, that maintains pools of quickly recycled chunks.
54 * In between, and for combinations of large and small requests, it does
55 the best it can trying to meet both goals at once.
56 * For very large requests (>= 128KB by default), it relies on system
57 memory mapping facilities, if supported.
59 For a longer but slightly out of date high-level description, see
60 http://gee.cs.oswego.edu/dl/html/malloc.html
62 You may already by default be using a C library containing a malloc
63 that is based on some version of this malloc (for example in
64 linux). You might still want to use the one in this file in order to
65 customize settings or to avoid overheads associated with library
66 versions.
68 * Contents, described in more detail in "description of public routines" below.
70 Standard (ANSI/SVID/...) functions:
71 malloc(size_t n);
72 calloc(size_t n_elements, size_t element_size);
73 free(Void_t* p);
74 realloc(Void_t* p, size_t n);
75 memalign(size_t alignment, size_t n);
76 valloc(size_t n);
77 mallinfo()
78 mallopt(int parameter_number, int parameter_value)
80 Additional functions:
81 independent_calloc(size_t n_elements, size_t size, Void_t* chunks[]);
82 independent_comalloc(size_t n_elements, size_t sizes[], Void_t* chunks[]);
83 pvalloc(size_t n);
84 cfree(Void_t* p);
85 malloc_trim(size_t pad);
86 malloc_usable_size(Void_t* p);
87 malloc_stats();
89 * Vital statistics:
91 Supported pointer representation: 4 or 8 bytes
92 Supported size_t representation: 4 or 8 bytes
93 Note that size_t is allowed to be 4 bytes even if pointers are 8.
94 You can adjust this by defining INTERNAL_SIZE_T
96 Alignment: 2 * sizeof(size_t) (default)
97 (i.e., 8 byte alignment with 4byte size_t). This suffices for
98 nearly all current machines and C compilers. However, you can
99 define MALLOC_ALIGNMENT to be wider than this if necessary.
101 Minimum overhead per allocated chunk: 4 or 8 bytes
102 Each malloced chunk has a hidden word of overhead holding size
103 and status information.
105 Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
106 8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
108 When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
109 ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
110 needed; 4 (8) for a trailing size field and 8 (16) bytes for
111 free list pointers. Thus, the minimum allocatable size is
112 16/24/32 bytes.
114 Even a request for zero bytes (i.e., malloc(0)) returns a
115 pointer to something of the minimum allocatable size.
117 The maximum overhead wastage (i.e., number of extra bytes
118 allocated than were requested in malloc) is less than or equal
119 to the minimum size, except for requests >= mmap_threshold that
120 are serviced via mmap(), where the worst case wastage is 2 *
121 sizeof(size_t) bytes plus the remainder from a system page (the
122 minimal mmap unit); typically 4096 or 8192 bytes.
124 Maximum allocated size: 4-byte size_t: 2^32 minus about two pages
125 8-byte size_t: 2^64 minus about two pages
127 It is assumed that (possibly signed) size_t values suffice to
128 represent chunk sizes. `Possibly signed' is due to the fact
129 that `size_t' may be defined on a system as either a signed or
130 an unsigned type. The ISO C standard says that it must be
131 unsigned, but a few systems are known not to adhere to this.
132 Additionally, even when size_t is unsigned, sbrk (which is by
133 default used to obtain memory from system) accepts signed
134 arguments, and may not be able to handle size_t-wide arguments
135 with negative sign bit. Generally, values that would
136 appear as negative after accounting for overhead and alignment
137 are supported only via mmap(), which does not have this
138 limitation.
140 Requests for sizes outside the allowed range will perform an optional
141 failure action and then return null. (Requests may also
142 also fail because a system is out of memory.)
144 Thread-safety: thread-safe unless NO_THREADS is defined
146 Compliance: I believe it is compliant with the 1997 Single Unix Specification
147 (See http://www.opennc.org). Also SVID/XPG, ANSI C, and probably
148 others as well.
150 * Synopsis of compile-time options:
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
155 Linux. It is also reported to work on WIN32 platforms.
156 People also report using it in stand-alone embedded systems.
158 The implementation is in straight, hand-tuned ANSI C. It is not
159 at all modular. (Sorry!) It uses a lot of macros. To be at all
160 usable, this code should be compiled using an optimizing compiler
161 (for example gcc -O3) that can simplify expressions and control
162 paths. (FAQ: some macros import variables as arguments rather than
163 declare locals because people reported that some debuggers
164 otherwise get confused.)
166 OPTION DEFAULT VALUE
168 Compilation Environment options:
170 __STD_C derived from C compiler defines
171 WIN32 NOT defined
172 HAVE_MEMCPY defined
173 USE_MEMCPY 1 if HAVE_MEMCPY is defined
174 HAVE_MMAP defined as 1
175 MMAP_CLEARS 1
176 HAVE_MREMAP 0 unless linux defined
177 USE_ARENAS the same as HAVE_MMAP
178 malloc_getpagesize derived from system #includes, or 4096 if not
179 HAVE_USR_INCLUDE_MALLOC_H NOT defined
180 LACKS_UNISTD_H NOT defined unless WIN32
181 LACKS_SYS_PARAM_H NOT defined unless WIN32
182 LACKS_SYS_MMAN_H NOT defined unless WIN32
184 Changing default word sizes:
186 INTERNAL_SIZE_T size_t
187 MALLOC_ALIGNMENT MAX (2 * sizeof(INTERNAL_SIZE_T),
188 __alignof__ (long double))
190 Configuration and functionality options:
192 USE_DL_PREFIX NOT defined
193 USE_PUBLIC_MALLOC_WRAPPERS NOT defined
194 USE_MALLOC_LOCK NOT defined
195 MALLOC_DEBUG NOT defined
196 REALLOC_ZERO_BYTES_FREES 1
197 MALLOC_FAILURE_ACTION errno = ENOMEM, if __STD_C defined, else no-op
198 TRIM_FASTBINS 0
200 Options for customizing MORECORE:
202 MORECORE sbrk
203 MORECORE_FAILURE -1
204 MORECORE_CONTIGUOUS 1
205 MORECORE_CANNOT_TRIM NOT defined
206 MORECORE_CLEARS 1
207 MMAP_AS_MORECORE_SIZE (1024 * 1024)
209 Tuning options that are also dynamically changeable via mallopt:
211 DEFAULT_MXFAST 64
212 DEFAULT_TRIM_THRESHOLD 128 * 1024
213 DEFAULT_TOP_PAD 0
214 DEFAULT_MMAP_THRESHOLD 128 * 1024
215 DEFAULT_MMAP_MAX 65536
217 There are several other #defined constants and macros that you
218 probably don't want to touch unless you are extending or adapting malloc. */
221 __STD_C should be nonzero if using ANSI-standard C compiler, a C++
222 compiler, or a C compiler sufficiently close to ANSI to get away
223 with it.
226 #ifndef __STD_C
227 #if defined(__STDC__) || defined(__cplusplus)
228 #define __STD_C 1
229 #else
230 #define __STD_C 0
231 #endif
232 #endif /*__STD_C*/
236 Void_t* is the pointer type that malloc should say it returns
239 #ifndef Void_t
240 #if (__STD_C || defined(WIN32))
241 #define Void_t void
242 #else
243 #define Void_t char
244 #endif
245 #endif /*Void_t*/
247 #if __STD_C
248 #include <stddef.h> /* for size_t */
249 #include <stdlib.h> /* for getenv(), abort() */
250 #else
251 #include <sys/types.h>
252 #endif
254 #include <malloc-machine.h>
256 #ifdef _LIBC
257 #include <stdio-common/_itoa.h>
258 #include <bits/wordsize.h>
259 #endif
261 #ifdef __cplusplus
262 extern "C" {
263 #endif
265 /* define LACKS_UNISTD_H if your system does not have a <unistd.h>. */
267 /* #define LACKS_UNISTD_H */
269 #ifndef LACKS_UNISTD_H
270 #include <unistd.h>
271 #endif
273 /* define LACKS_SYS_PARAM_H if your system does not have a <sys/param.h>. */
275 /* #define LACKS_SYS_PARAM_H */
278 #include <stdio.h> /* needed for malloc_stats */
279 #include <errno.h> /* needed for optional MALLOC_FAILURE_ACTION */
281 /* For uintptr_t. */
282 #include <stdint.h>
284 /* For va_arg, va_start, va_end. */
285 #include <stdarg.h>
287 /* For writev and struct iovec. */
288 #include <sys/uio.h>
289 /* For syslog. */
290 #include <sys/syslog.h>
292 /* For various dynamic linking things. */
293 #include <dlfcn.h>
297 Debugging:
299 Because freed chunks may be overwritten with bookkeeping fields, this
300 malloc will often die when freed memory is overwritten by user
301 programs. This can be very effective (albeit in an annoying way)
302 in helping track down dangling pointers.
304 If you compile with -DMALLOC_DEBUG, a number of assertion checks are
305 enabled that will catch more memory errors. You probably won't be
306 able to make much sense of the actual assertion errors, but they
307 should help you locate incorrectly overwritten memory. The checking
308 is fairly extensive, and will slow down execution
309 noticeably. Calling malloc_stats or mallinfo with MALLOC_DEBUG set
310 will attempt to check every non-mmapped allocated and free chunk in
311 the course of computing the summmaries. (By nature, mmapped regions
312 cannot be checked very much automatically.)
314 Setting MALLOC_DEBUG may also be helpful if you are trying to modify
315 this code. The assertions in the check routines spell out in more
316 detail the assumptions and invariants underlying the algorithms.
318 Setting MALLOC_DEBUG does NOT provide an automated mechanism for
319 checking that all accesses to malloced memory stay within their
320 bounds. However, there are several add-ons and adaptations of this
321 or other mallocs available that do this.
324 #if MALLOC_DEBUG
325 #include <assert.h>
326 #else
327 #undef assert
328 #define assert(x) ((void)0)
329 #endif
333 INTERNAL_SIZE_T is the word-size used for internal bookkeeping
334 of chunk sizes.
336 The default version is the same as size_t.
338 While not strictly necessary, it is best to define this as an
339 unsigned type, even if size_t is a signed type. This may avoid some
340 artificial size limitations on some systems.
342 On a 64-bit machine, you may be able to reduce malloc overhead by
343 defining INTERNAL_SIZE_T to be a 32 bit `unsigned int' at the
344 expense of not being able to handle more than 2^32 of malloced
345 space. If this limitation is acceptable, you are encouraged to set
346 this unless you are on a platform requiring 16byte alignments. In
347 this case the alignment requirements turn out to negate any
348 potential advantages of decreasing size_t word size.
350 Implementors: Beware of the possible combinations of:
351 - INTERNAL_SIZE_T might be signed or unsigned, might be 32 or 64 bits,
352 and might be the same width as int or as long
353 - size_t might have different width and signedness as INTERNAL_SIZE_T
354 - int and long might be 32 or 64 bits, and might be the same width
355 To deal with this, most comparisons and difference computations
356 among INTERNAL_SIZE_Ts should cast them to unsigned long, being
357 aware of the fact that casting an unsigned int to a wider long does
358 not sign-extend. (This also makes checking for negative numbers
359 awkward.) Some of these casts result in harmless compiler warnings
360 on some systems.
363 #ifndef INTERNAL_SIZE_T
364 #define INTERNAL_SIZE_T size_t
365 #endif
367 /* The corresponding word size */
368 #define SIZE_SZ (sizeof(INTERNAL_SIZE_T))
372 MALLOC_ALIGNMENT is the minimum alignment for malloc'ed chunks.
373 It must be a power of two at least 2 * SIZE_SZ, even on machines
374 for which smaller alignments would suffice. It may be defined as
375 larger than this though. Note however that code and data structures
376 are optimized for the case of 8-byte alignment.
380 #ifndef MALLOC_ALIGNMENT
381 /* XXX This is the correct definition. It differs from 2*SIZE_SZ only on
382 powerpc32. For the time being, changing this is causing more
383 compatibility problems due to malloc_get_state/malloc_set_state than
384 will returning blocks not adequately aligned for long double objects
385 under -mlong-double-128.
387 #define MALLOC_ALIGNMENT (2 * SIZE_SZ < __alignof__ (long double) \
388 ? __alignof__ (long double) : 2 * SIZE_SZ)
390 #define MALLOC_ALIGNMENT (2 * SIZE_SZ)
391 #endif
393 /* The corresponding bit mask value */
394 #define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1)
399 REALLOC_ZERO_BYTES_FREES should be set if a call to
400 realloc with zero bytes should be the same as a call to free.
401 This is required by the C standard. Otherwise, since this malloc
402 returns a unique pointer for malloc(0), so does realloc(p, 0).
405 #ifndef REALLOC_ZERO_BYTES_FREES
406 #define REALLOC_ZERO_BYTES_FREES 1
407 #endif
410 TRIM_FASTBINS controls whether free() of a very small chunk can
411 immediately lead to trimming. Setting to true (1) can reduce memory
412 footprint, but will almost always slow down programs that use a lot
413 of small chunks.
415 Define this only if you are willing to give up some speed to more
416 aggressively reduce system-level memory footprint when releasing
417 memory in programs that use many small chunks. You can get
418 essentially the same effect by setting MXFAST to 0, but this can
419 lead to even greater slowdowns in programs using many small chunks.
420 TRIM_FASTBINS is an in-between compile-time option, that disables
421 only those chunks bordering topmost memory from being placed in
422 fastbins.
425 #ifndef TRIM_FASTBINS
426 #define TRIM_FASTBINS 0
427 #endif
431 USE_DL_PREFIX will prefix all public routines with the string 'dl'.
432 This is necessary when you only want to use this malloc in one part
433 of a program, using your regular system malloc elsewhere.
436 /* #define USE_DL_PREFIX */
440 Two-phase name translation.
441 All of the actual routines are given mangled names.
442 When wrappers are used, they become the public callable versions.
443 When DL_PREFIX is used, the callable names are prefixed.
446 #ifdef USE_DL_PREFIX
447 #define public_cALLOc dlcalloc
448 #define public_fREe dlfree
449 #define public_cFREe dlcfree
450 #define public_mALLOc dlmalloc
451 #define public_mEMALIGn dlmemalign
452 #define public_rEALLOc dlrealloc
453 #define public_vALLOc dlvalloc
454 #define public_pVALLOc dlpvalloc
455 #define public_mALLINFo dlmallinfo
456 #define public_mALLOPt dlmallopt
457 #define public_mTRIm dlmalloc_trim
458 #define public_mSTATs dlmalloc_stats
459 #define public_mUSABLe dlmalloc_usable_size
460 #define public_iCALLOc dlindependent_calloc
461 #define public_iCOMALLOc dlindependent_comalloc
462 #define public_gET_STATe dlget_state
463 #define public_sET_STATe dlset_state
464 #else /* USE_DL_PREFIX */
465 #ifdef _LIBC
467 /* Special defines for the GNU C library. */
468 #define public_cALLOc __libc_calloc
469 #define public_fREe __libc_free
470 #define public_cFREe __libc_cfree
471 #define public_mALLOc __libc_malloc
472 #define public_mEMALIGn __libc_memalign
473 #define public_rEALLOc __libc_realloc
474 #define public_vALLOc __libc_valloc
475 #define public_pVALLOc __libc_pvalloc
476 #define public_mALLINFo __libc_mallinfo
477 #define public_mALLOPt __libc_mallopt
478 #define public_mTRIm __malloc_trim
479 #define public_mSTATs __malloc_stats
480 #define public_mUSABLe __malloc_usable_size
481 #define public_iCALLOc __libc_independent_calloc
482 #define public_iCOMALLOc __libc_independent_comalloc
483 #define public_gET_STATe __malloc_get_state
484 #define public_sET_STATe __malloc_set_state
485 #define malloc_getpagesize __getpagesize()
486 #define open __open
487 #define mmap __mmap
488 #define munmap __munmap
489 #define mremap __mremap
490 #define mprotect __mprotect
491 #define MORECORE (*__morecore)
492 #define MORECORE_FAILURE 0
494 Void_t * __default_morecore (ptrdiff_t);
495 Void_t *(*__morecore)(ptrdiff_t) = __default_morecore;
497 #else /* !_LIBC */
498 #define public_cALLOc calloc
499 #define public_fREe free
500 #define public_cFREe cfree
501 #define public_mALLOc malloc
502 #define public_mEMALIGn memalign
503 #define public_rEALLOc realloc
504 #define public_vALLOc valloc
505 #define public_pVALLOc pvalloc
506 #define public_mALLINFo mallinfo
507 #define public_mALLOPt mallopt
508 #define public_mTRIm malloc_trim
509 #define public_mSTATs malloc_stats
510 #define public_mUSABLe malloc_usable_size
511 #define public_iCALLOc independent_calloc
512 #define public_iCOMALLOc independent_comalloc
513 #define public_gET_STATe malloc_get_state
514 #define public_sET_STATe malloc_set_state
515 #endif /* _LIBC */
516 #endif /* USE_DL_PREFIX */
518 #ifndef _LIBC
519 #define __builtin_expect(expr, val) (expr)
521 #define fwrite(buf, size, count, fp) _IO_fwrite (buf, size, count, fp)
522 #endif
525 HAVE_MEMCPY should be defined if you are not otherwise using
526 ANSI STD C, but still have memcpy and memset in your C library
527 and want to use them in calloc and realloc. Otherwise simple
528 macro versions are defined below.
530 USE_MEMCPY should be defined as 1 if you actually want to
531 have memset and memcpy called. People report that the macro
532 versions are faster than libc versions on some systems.
534 Even if USE_MEMCPY is set to 1, loops to copy/clear small chunks
535 (of <= 36 bytes) are manually unrolled in realloc and calloc.
538 #define HAVE_MEMCPY
540 #ifndef USE_MEMCPY
541 #ifdef HAVE_MEMCPY
542 #define USE_MEMCPY 1
543 #else
544 #define USE_MEMCPY 0
545 #endif
546 #endif
549 #if (__STD_C || defined(HAVE_MEMCPY))
551 #ifdef _LIBC
552 # include <string.h>
553 #else
554 #ifdef WIN32
555 /* On Win32 memset and memcpy are already declared in windows.h */
556 #else
557 #if __STD_C
558 void* memset(void*, int, size_t);
559 void* memcpy(void*, const void*, size_t);
560 #else
561 Void_t* memset();
562 Void_t* memcpy();
563 #endif
564 #endif
565 #endif
566 #endif
569 MALLOC_FAILURE_ACTION is the action to take before "return 0" when
570 malloc fails to be able to return memory, either because memory is
571 exhausted or because of illegal arguments.
573 By default, sets errno if running on STD_C platform, else does nothing.
576 #ifndef MALLOC_FAILURE_ACTION
577 #if __STD_C
578 #define MALLOC_FAILURE_ACTION \
579 errno = ENOMEM;
581 #else
582 #define MALLOC_FAILURE_ACTION
583 #endif
584 #endif
587 MORECORE-related declarations. By default, rely on sbrk
591 #ifdef LACKS_UNISTD_H
592 #if !defined(__FreeBSD__) && !defined(__OpenBSD__) && !defined(__NetBSD__)
593 #if __STD_C
594 extern Void_t* sbrk(ptrdiff_t);
595 #else
596 extern Void_t* sbrk();
597 #endif
598 #endif
599 #endif
602 MORECORE is the name of the routine to call to obtain more memory
603 from the system. See below for general guidance on writing
604 alternative MORECORE functions, as well as a version for WIN32 and a
605 sample version for pre-OSX macos.
608 #ifndef MORECORE
609 #define MORECORE sbrk
610 #endif
613 MORECORE_FAILURE is the value returned upon failure of MORECORE
614 as well as mmap. Since it cannot be an otherwise valid memory address,
615 and must reflect values of standard sys calls, you probably ought not
616 try to redefine it.
619 #ifndef MORECORE_FAILURE
620 #define MORECORE_FAILURE (-1)
621 #endif
624 If MORECORE_CONTIGUOUS is true, take advantage of fact that
625 consecutive calls to MORECORE with positive arguments always return
626 contiguous increasing addresses. This is true of unix sbrk. Even
627 if not defined, when regions happen to be contiguous, malloc will
628 permit allocations spanning regions obtained from different
629 calls. But defining this when applicable enables some stronger
630 consistency checks and space efficiencies.
633 #ifndef MORECORE_CONTIGUOUS
634 #define MORECORE_CONTIGUOUS 1
635 #endif
638 Define MORECORE_CANNOT_TRIM if your version of MORECORE
639 cannot release space back to the system when given negative
640 arguments. This is generally necessary only if you are using
641 a hand-crafted MORECORE function that cannot handle negative arguments.
644 /* #define MORECORE_CANNOT_TRIM */
646 /* MORECORE_CLEARS (default 1)
647 The degree to which the routine mapped to MORECORE zeroes out
648 memory: never (0), only for newly allocated space (1) or always
649 (2). The distinction between (1) and (2) is necessary because on
650 some systems, if the application first decrements and then
651 increments the break value, the contents of the reallocated space
652 are unspecified.
655 #ifndef MORECORE_CLEARS
656 #define MORECORE_CLEARS 1
657 #endif
661 Define HAVE_MMAP as true to optionally make malloc() use mmap() to
662 allocate very large blocks. These will be returned to the
663 operating system immediately after a free(). Also, if mmap
664 is available, it is used as a backup strategy in cases where
665 MORECORE fails to provide space from system.
667 This malloc is best tuned to work with mmap for large requests.
668 If you do not have mmap, operations involving very large chunks (1MB
669 or so) may be slower than you'd like.
672 #ifndef HAVE_MMAP
673 #define HAVE_MMAP 1
676 Standard unix mmap using /dev/zero clears memory so calloc doesn't
677 need to.
680 #ifndef MMAP_CLEARS
681 #define MMAP_CLEARS 1
682 #endif
684 #else /* no mmap */
685 #ifndef MMAP_CLEARS
686 #define MMAP_CLEARS 0
687 #endif
688 #endif
692 MMAP_AS_MORECORE_SIZE is the minimum mmap size argument to use if
693 sbrk fails, and mmap is used as a backup (which is done only if
694 HAVE_MMAP). The value must be a multiple of page size. This
695 backup strategy generally applies only when systems have "holes" in
696 address space, so sbrk cannot perform contiguous expansion, but
697 there is still space available on system. On systems for which
698 this is known to be useful (i.e. most linux kernels), this occurs
699 only when programs allocate huge amounts of memory. Between this,
700 and the fact that mmap regions tend to be limited, the size should
701 be large, to avoid too many mmap calls and thus avoid running out
702 of kernel resources.
705 #ifndef MMAP_AS_MORECORE_SIZE
706 #define MMAP_AS_MORECORE_SIZE (1024 * 1024)
707 #endif
710 Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
711 large blocks. This is currently only possible on Linux with
712 kernel versions newer than 1.3.77.
715 #ifndef HAVE_MREMAP
716 #ifdef linux
717 #define HAVE_MREMAP 1
718 #else
719 #define HAVE_MREMAP 0
720 #endif
722 #endif /* HAVE_MMAP */
724 /* Define USE_ARENAS to enable support for multiple `arenas'. These
725 are allocated using mmap(), are necessary for threads and
726 occasionally useful to overcome address space limitations affecting
727 sbrk(). */
729 #ifndef USE_ARENAS
730 #define USE_ARENAS HAVE_MMAP
731 #endif
735 The system page size. To the extent possible, this malloc manages
736 memory from the system in page-size units. Note that this value is
737 cached during initialization into a field of malloc_state. So even
738 if malloc_getpagesize is a function, it is only called once.
740 The following mechanics for getpagesize were adapted from bsd/gnu
741 getpagesize.h. If none of the system-probes here apply, a value of
742 4096 is used, which should be OK: If they don't apply, then using
743 the actual value probably doesn't impact performance.
747 #ifndef malloc_getpagesize
749 #ifndef LACKS_UNISTD_H
750 # include <unistd.h>
751 #endif
753 # ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
754 # ifndef _SC_PAGE_SIZE
755 # define _SC_PAGE_SIZE _SC_PAGESIZE
756 # endif
757 # endif
759 # ifdef _SC_PAGE_SIZE
760 # define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
761 # else
762 # if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
763 extern size_t getpagesize();
764 # define malloc_getpagesize getpagesize()
765 # else
766 # ifdef WIN32 /* use supplied emulation of getpagesize */
767 # define malloc_getpagesize getpagesize()
768 # else
769 # ifndef LACKS_SYS_PARAM_H
770 # include <sys/param.h>
771 # endif
772 # ifdef EXEC_PAGESIZE
773 # define malloc_getpagesize EXEC_PAGESIZE
774 # else
775 # ifdef NBPG
776 # ifndef CLSIZE
777 # define malloc_getpagesize NBPG
778 # else
779 # define malloc_getpagesize (NBPG * CLSIZE)
780 # endif
781 # else
782 # ifdef NBPC
783 # define malloc_getpagesize NBPC
784 # else
785 # ifdef PAGESIZE
786 # define malloc_getpagesize PAGESIZE
787 # else /* just guess */
788 # define malloc_getpagesize (4096)
789 # endif
790 # endif
791 # endif
792 # endif
793 # endif
794 # endif
795 # endif
796 #endif
799 This version of malloc supports the standard SVID/XPG mallinfo
800 routine that returns a struct containing usage properties and
801 statistics. It should work on any SVID/XPG compliant system that has
802 a /usr/include/malloc.h defining struct mallinfo. (If you'd like to
803 install such a thing yourself, cut out the preliminary declarations
804 as described above and below and save them in a malloc.h file. But
805 there's no compelling reason to bother to do this.)
807 The main declaration needed is the mallinfo struct that is returned
808 (by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
809 bunch of fields that are not even meaningful in this version of
810 malloc. These fields are are instead filled by mallinfo() with
811 other numbers that might be of interest.
813 HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
814 /usr/include/malloc.h file that includes a declaration of struct
815 mallinfo. If so, it is included; else an SVID2/XPG2 compliant
816 version is declared below. These must be precisely the same for
817 mallinfo() to work. The original SVID version of this struct,
818 defined on most systems with mallinfo, declares all fields as
819 ints. But some others define as unsigned long. If your system
820 defines the fields using a type of different width than listed here,
821 you must #include your system version and #define
822 HAVE_USR_INCLUDE_MALLOC_H.
825 /* #define HAVE_USR_INCLUDE_MALLOC_H */
827 #ifdef HAVE_USR_INCLUDE_MALLOC_H
828 #include "/usr/include/malloc.h"
829 #endif
832 /* ---------- description of public routines ------------ */
835 malloc(size_t n)
836 Returns a pointer to a newly allocated chunk of at least n bytes, or null
837 if no space is available. Additionally, on failure, errno is
838 set to ENOMEM on ANSI C systems.
840 If n is zero, malloc returns a minumum-sized chunk. (The minimum
841 size is 16 bytes on most 32bit systems, and 24 or 32 bytes on 64bit
842 systems.) On most systems, size_t is an unsigned type, so calls
843 with negative arguments are interpreted as requests for huge amounts
844 of space, which will often fail. The maximum supported value of n
845 differs across systems, but is in all cases less than the maximum
846 representable value of a size_t.
848 #if __STD_C
849 Void_t* public_mALLOc(size_t);
850 #else
851 Void_t* public_mALLOc();
852 #endif
853 #ifdef libc_hidden_proto
854 libc_hidden_proto (public_mALLOc)
855 #endif
858 free(Void_t* p)
859 Releases the chunk of memory pointed to by p, that had been previously
860 allocated using malloc or a related routine such as realloc.
861 It has no effect if p is null. It can have arbitrary (i.e., bad!)
862 effects if p has already been freed.
864 Unless disabled (using mallopt), freeing very large spaces will
865 when possible, automatically trigger operations that give
866 back unused memory to the system, thus reducing program footprint.
868 #if __STD_C
869 void public_fREe(Void_t*);
870 #else
871 void public_fREe();
872 #endif
873 #ifdef libc_hidden_proto
874 libc_hidden_proto (public_fREe)
875 #endif
878 calloc(size_t n_elements, size_t element_size);
879 Returns a pointer to n_elements * element_size bytes, with all locations
880 set to zero.
882 #if __STD_C
883 Void_t* public_cALLOc(size_t, size_t);
884 #else
885 Void_t* public_cALLOc();
886 #endif
889 realloc(Void_t* p, size_t n)
890 Returns a pointer to a chunk of size n that contains the same data
891 as does chunk p up to the minimum of (n, p's size) bytes, or null
892 if no space is available.
894 The returned pointer may or may not be the same as p. The algorithm
895 prefers extending p when possible, otherwise it employs the
896 equivalent of a malloc-copy-free sequence.
898 If p is null, realloc is equivalent to malloc.
900 If space is not available, realloc returns null, errno is set (if on
901 ANSI) and p is NOT freed.
903 if n is for fewer bytes than already held by p, the newly unused
904 space is lopped off and freed if possible. Unless the #define
905 REALLOC_ZERO_BYTES_FREES is set, realloc with a size argument of
906 zero (re)allocates a minimum-sized chunk.
908 Large chunks that were internally obtained via mmap will always
909 be reallocated using malloc-copy-free sequences unless
910 the system supports MREMAP (currently only linux).
912 The old unix realloc convention of allowing the last-free'd chunk
913 to be used as an argument to realloc is not supported.
915 #if __STD_C
916 Void_t* public_rEALLOc(Void_t*, size_t);
917 #else
918 Void_t* public_rEALLOc();
919 #endif
920 #ifdef libc_hidden_proto
921 libc_hidden_proto (public_rEALLOc)
922 #endif
925 memalign(size_t alignment, size_t n);
926 Returns a pointer to a newly allocated chunk of n bytes, aligned
927 in accord with the alignment argument.
929 The alignment argument should be a power of two. If the argument is
930 not a power of two, the nearest greater power is used.
931 8-byte alignment is guaranteed by normal malloc calls, so don't
932 bother calling memalign with an argument of 8 or less.
934 Overreliance on memalign is a sure way to fragment space.
936 #if __STD_C
937 Void_t* public_mEMALIGn(size_t, size_t);
938 #else
939 Void_t* public_mEMALIGn();
940 #endif
941 #ifdef libc_hidden_proto
942 libc_hidden_proto (public_mEMALIGn)
943 #endif
946 valloc(size_t n);
947 Equivalent to memalign(pagesize, n), where pagesize is the page
948 size of the system. If the pagesize is unknown, 4096 is used.
950 #if __STD_C
951 Void_t* public_vALLOc(size_t);
952 #else
953 Void_t* public_vALLOc();
954 #endif
959 mallopt(int parameter_number, int parameter_value)
960 Sets tunable parameters The format is to provide a
961 (parameter-number, parameter-value) pair. mallopt then sets the
962 corresponding parameter to the argument value if it can (i.e., so
963 long as the value is meaningful), and returns 1 if successful else
964 0. SVID/XPG/ANSI defines four standard param numbers for mallopt,
965 normally defined in malloc.h. Only one of these (M_MXFAST) is used
966 in this malloc. The others (M_NLBLKS, M_GRAIN, M_KEEP) don't apply,
967 so setting them has no effect. But this malloc also supports four
968 other options in mallopt. See below for details. Briefly, supported
969 parameters are as follows (listed defaults are for "typical"
970 configurations).
972 Symbol param # default allowed param values
973 M_MXFAST 1 64 0-80 (0 disables fastbins)
974 M_TRIM_THRESHOLD -1 128*1024 any (-1U disables trimming)
975 M_TOP_PAD -2 0 any
976 M_MMAP_THRESHOLD -3 128*1024 any (or 0 if no MMAP support)
977 M_MMAP_MAX -4 65536 any (0 disables use of mmap)
979 #if __STD_C
980 int public_mALLOPt(int, int);
981 #else
982 int public_mALLOPt();
983 #endif
987 mallinfo()
988 Returns (by copy) a struct containing various summary statistics:
990 arena: current total non-mmapped bytes allocated from system
991 ordblks: the number of free chunks
992 smblks: the number of fastbin blocks (i.e., small chunks that
993 have been freed but not use resused or consolidated)
994 hblks: current number of mmapped regions
995 hblkhd: total bytes held in mmapped regions
996 usmblks: the maximum total allocated space. This will be greater
997 than current total if trimming has occurred.
998 fsmblks: total bytes held in fastbin blocks
999 uordblks: current total allocated space (normal or mmapped)
1000 fordblks: total free space
1001 keepcost: the maximum number of bytes that could ideally be released
1002 back to system via malloc_trim. ("ideally" means that
1003 it ignores page restrictions etc.)
1005 Because these fields are ints, but internal bookkeeping may
1006 be kept as longs, the reported values may wrap around zero and
1007 thus be inaccurate.
1009 #if __STD_C
1010 struct mallinfo public_mALLINFo(void);
1011 #else
1012 struct mallinfo public_mALLINFo();
1013 #endif
1015 #ifndef _LIBC
1017 independent_calloc(size_t n_elements, size_t element_size, Void_t* chunks[]);
1019 independent_calloc is similar to calloc, but instead of returning a
1020 single cleared space, it returns an array of pointers to n_elements
1021 independent elements that can hold contents of size elem_size, each
1022 of which starts out cleared, and can be independently freed,
1023 realloc'ed etc. The elements are guaranteed to be adjacently
1024 allocated (this is not guaranteed to occur with multiple callocs or
1025 mallocs), which may also improve cache locality in some
1026 applications.
1028 The "chunks" argument is optional (i.e., may be null, which is
1029 probably the most typical usage). If it is null, the returned array
1030 is itself dynamically allocated and should also be freed when it is
1031 no longer needed. Otherwise, the chunks array must be of at least
1032 n_elements in length. It is filled in with the pointers to the
1033 chunks.
1035 In either case, independent_calloc returns this pointer array, or
1036 null if the allocation failed. If n_elements is zero and "chunks"
1037 is null, it returns a chunk representing an array with zero elements
1038 (which should be freed if not wanted).
1040 Each element must be individually freed when it is no longer
1041 needed. If you'd like to instead be able to free all at once, you
1042 should instead use regular calloc and assign pointers into this
1043 space to represent elements. (In this case though, you cannot
1044 independently free elements.)
1046 independent_calloc simplifies and speeds up implementations of many
1047 kinds of pools. It may also be useful when constructing large data
1048 structures that initially have a fixed number of fixed-sized nodes,
1049 but the number is not known at compile time, and some of the nodes
1050 may later need to be freed. For example:
1052 struct Node { int item; struct Node* next; };
1054 struct Node* build_list() {
1055 struct Node** pool;
1056 int n = read_number_of_nodes_needed();
1057 if (n <= 0) return 0;
1058 pool = (struct Node**)(independent_calloc(n, sizeof(struct Node), 0);
1059 if (pool == 0) die();
1060 // organize into a linked list...
1061 struct Node* first = pool[0];
1062 for (i = 0; i < n-1; ++i)
1063 pool[i]->next = pool[i+1];
1064 free(pool); // Can now free the array (or not, if it is needed later)
1065 return first;
1068 #if __STD_C
1069 Void_t** public_iCALLOc(size_t, size_t, Void_t**);
1070 #else
1071 Void_t** public_iCALLOc();
1072 #endif
1075 independent_comalloc(size_t n_elements, size_t sizes[], Void_t* chunks[]);
1077 independent_comalloc allocates, all at once, a set of n_elements
1078 chunks with sizes indicated in the "sizes" array. It returns
1079 an array of pointers to these elements, each of which can be
1080 independently freed, realloc'ed etc. The elements are guaranteed to
1081 be adjacently allocated (this is not guaranteed to occur with
1082 multiple callocs or mallocs), which may also improve cache locality
1083 in some applications.
1085 The "chunks" argument is optional (i.e., may be null). If it is null
1086 the returned array is itself dynamically allocated and should also
1087 be freed when it is no longer needed. Otherwise, the chunks array
1088 must be of at least n_elements in length. It is filled in with the
1089 pointers to the chunks.
1091 In either case, independent_comalloc returns this pointer array, or
1092 null if the allocation failed. If n_elements is zero and chunks is
1093 null, it returns a chunk representing an array with zero elements
1094 (which should be freed if not wanted).
1096 Each element must be individually freed when it is no longer
1097 needed. If you'd like to instead be able to free all at once, you
1098 should instead use a single regular malloc, and assign pointers at
1099 particular offsets in the aggregate space. (In this case though, you
1100 cannot independently free elements.)
1102 independent_comallac differs from independent_calloc in that each
1103 element may have a different size, and also that it does not
1104 automatically clear elements.
1106 independent_comalloc can be used to speed up allocation in cases
1107 where several structs or objects must always be allocated at the
1108 same time. For example:
1110 struct Head { ... }
1111 struct Foot { ... }
1113 void send_message(char* msg) {
1114 int msglen = strlen(msg);
1115 size_t sizes[3] = { sizeof(struct Head), msglen, sizeof(struct Foot) };
1116 void* chunks[3];
1117 if (independent_comalloc(3, sizes, chunks) == 0)
1118 die();
1119 struct Head* head = (struct Head*)(chunks[0]);
1120 char* body = (char*)(chunks[1]);
1121 struct Foot* foot = (struct Foot*)(chunks[2]);
1122 // ...
1125 In general though, independent_comalloc is worth using only for
1126 larger values of n_elements. For small values, you probably won't
1127 detect enough difference from series of malloc calls to bother.
1129 Overuse of independent_comalloc can increase overall memory usage,
1130 since it cannot reuse existing noncontiguous small chunks that
1131 might be available for some of the elements.
1133 #if __STD_C
1134 Void_t** public_iCOMALLOc(size_t, size_t*, Void_t**);
1135 #else
1136 Void_t** public_iCOMALLOc();
1137 #endif
1139 #endif /* _LIBC */
1143 pvalloc(size_t n);
1144 Equivalent to valloc(minimum-page-that-holds(n)), that is,
1145 round up n to nearest pagesize.
1147 #if __STD_C
1148 Void_t* public_pVALLOc(size_t);
1149 #else
1150 Void_t* public_pVALLOc();
1151 #endif
1154 cfree(Void_t* p);
1155 Equivalent to free(p).
1157 cfree is needed/defined on some systems that pair it with calloc,
1158 for odd historical reasons (such as: cfree is used in example
1159 code in the first edition of K&R).
1161 #if __STD_C
1162 void public_cFREe(Void_t*);
1163 #else
1164 void public_cFREe();
1165 #endif
1168 malloc_trim(size_t pad);
1170 If possible, gives memory back to the system (via negative
1171 arguments to sbrk) if there is unused memory at the `high' end of
1172 the malloc pool. You can call this after freeing large blocks of
1173 memory to potentially reduce the system-level memory requirements
1174 of a program. However, it cannot guarantee to reduce memory. Under
1175 some allocation patterns, some large free blocks of memory will be
1176 locked between two used chunks, so they cannot be given back to
1177 the system.
1179 The `pad' argument to malloc_trim represents the amount of free
1180 trailing space to leave untrimmed. If this argument is zero,
1181 only the minimum amount of memory to maintain internal data
1182 structures will be left (one page or less). Non-zero arguments
1183 can be supplied to maintain enough trailing space to service
1184 future expected allocations without having to re-obtain memory
1185 from the system.
1187 Malloc_trim returns 1 if it actually released any memory, else 0.
1188 On systems that do not support "negative sbrks", it will always
1189 return 0.
1191 #if __STD_C
1192 int public_mTRIm(size_t);
1193 #else
1194 int public_mTRIm();
1195 #endif
1198 malloc_usable_size(Void_t* p);
1200 Returns the number of bytes you can actually use in
1201 an allocated chunk, which may be more than you requested (although
1202 often not) due to alignment and minimum size constraints.
1203 You can use this many bytes without worrying about
1204 overwriting other allocated objects. This is not a particularly great
1205 programming practice. malloc_usable_size can be more useful in
1206 debugging and assertions, for example:
1208 p = malloc(n);
1209 assert(malloc_usable_size(p) >= 256);
1212 #if __STD_C
1213 size_t public_mUSABLe(Void_t*);
1214 #else
1215 size_t public_mUSABLe();
1216 #endif
1219 malloc_stats();
1220 Prints on stderr the amount of space obtained from the system (both
1221 via sbrk and mmap), the maximum amount (which may be more than
1222 current if malloc_trim and/or munmap got called), and the current
1223 number of bytes allocated via malloc (or realloc, etc) but not yet
1224 freed. Note that this is the number of bytes allocated, not the
1225 number requested. It will be larger than the number requested
1226 because of alignment and bookkeeping overhead. Because it includes
1227 alignment wastage as being in use, this figure may be greater than
1228 zero even when no user-level chunks are allocated.
1230 The reported current and maximum system memory can be inaccurate if
1231 a program makes other calls to system memory allocation functions
1232 (normally sbrk) outside of malloc.
1234 malloc_stats prints only the most commonly interesting statistics.
1235 More information can be obtained by calling mallinfo.
1238 #if __STD_C
1239 void public_mSTATs(void);
1240 #else
1241 void public_mSTATs();
1242 #endif
1245 malloc_get_state(void);
1247 Returns the state of all malloc variables in an opaque data
1248 structure.
1250 #if __STD_C
1251 Void_t* public_gET_STATe(void);
1252 #else
1253 Void_t* public_gET_STATe();
1254 #endif
1257 malloc_set_state(Void_t* state);
1259 Restore the state of all malloc variables from data obtained with
1260 malloc_get_state().
1262 #if __STD_C
1263 int public_sET_STATe(Void_t*);
1264 #else
1265 int public_sET_STATe();
1266 #endif
1268 #ifdef _LIBC
1270 posix_memalign(void **memptr, size_t alignment, size_t size);
1272 POSIX wrapper like memalign(), checking for validity of size.
1274 int __posix_memalign(void **, size_t, size_t);
1275 #endif
1277 /* mallopt tuning options */
1280 M_MXFAST is the maximum request size used for "fastbins", special bins
1281 that hold returned chunks without consolidating their spaces. This
1282 enables future requests for chunks of the same size to be handled
1283 very quickly, but can increase fragmentation, and thus increase the
1284 overall memory footprint of a program.
1286 This malloc manages fastbins very conservatively yet still
1287 efficiently, so fragmentation is rarely a problem for values less
1288 than or equal to the default. The maximum supported value of MXFAST
1289 is 80. You wouldn't want it any higher than this anyway. Fastbins
1290 are designed especially for use with many small structs, objects or
1291 strings -- the default handles structs/objects/arrays with sizes up
1292 to 8 4byte fields, or small strings representing words, tokens,
1293 etc. Using fastbins for larger objects normally worsens
1294 fragmentation without improving speed.
1296 M_MXFAST is set in REQUEST size units. It is internally used in
1297 chunksize units, which adds padding and alignment. You can reduce
1298 M_MXFAST to 0 to disable all use of fastbins. This causes the malloc
1299 algorithm to be a closer approximation of fifo-best-fit in all cases,
1300 not just for larger requests, but will generally cause it to be
1301 slower.
1305 /* M_MXFAST is a standard SVID/XPG tuning option, usually listed in malloc.h */
1306 #ifndef M_MXFAST
1307 #define M_MXFAST 1
1308 #endif
1310 #ifndef DEFAULT_MXFAST
1311 #define DEFAULT_MXFAST 64
1312 #endif
1316 M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
1317 to keep before releasing via malloc_trim in free().
1319 Automatic trimming is mainly useful in long-lived programs.
1320 Because trimming via sbrk can be slow on some systems, and can
1321 sometimes be wasteful (in cases where programs immediately
1322 afterward allocate more large chunks) the value should be high
1323 enough so that your overall system performance would improve by
1324 releasing this much memory.
1326 The trim threshold and the mmap control parameters (see below)
1327 can be traded off with one another. Trimming and mmapping are
1328 two different ways of releasing unused memory back to the
1329 system. Between these two, it is often possible to keep
1330 system-level demands of a long-lived program down to a bare
1331 minimum. For example, in one test suite of sessions measuring
1332 the XF86 X server on Linux, using a trim threshold of 128K and a
1333 mmap threshold of 192K led to near-minimal long term resource
1334 consumption.
1336 If you are using this malloc in a long-lived program, it should
1337 pay to experiment with these values. As a rough guide, you
1338 might set to a value close to the average size of a process
1339 (program) running on your system. Releasing this much memory
1340 would allow such a process to run in memory. Generally, it's
1341 worth it to tune for trimming rather tham memory mapping when a
1342 program undergoes phases where several large chunks are
1343 allocated and released in ways that can reuse each other's
1344 storage, perhaps mixed with phases where there are no such
1345 chunks at all. And in well-behaved long-lived programs,
1346 controlling release of large blocks via trimming versus mapping
1347 is usually faster.
1349 However, in most programs, these parameters serve mainly as
1350 protection against the system-level effects of carrying around
1351 massive amounts of unneeded memory. Since frequent calls to
1352 sbrk, mmap, and munmap otherwise degrade performance, the default
1353 parameters are set to relatively high values that serve only as
1354 safeguards.
1356 The trim value It must be greater than page size to have any useful
1357 effect. To disable trimming completely, you can set to
1358 (unsigned long)(-1)
1360 Trim settings interact with fastbin (MXFAST) settings: Unless
1361 TRIM_FASTBINS is defined, automatic trimming never takes place upon
1362 freeing a chunk with size less than or equal to MXFAST. Trimming is
1363 instead delayed until subsequent freeing of larger chunks. However,
1364 you can still force an attempted trim by calling malloc_trim.
1366 Also, trimming is not generally possible in cases where
1367 the main arena is obtained via mmap.
1369 Note that the trick some people use of mallocing a huge space and
1370 then freeing it at program startup, in an attempt to reserve system
1371 memory, doesn't have the intended effect under automatic trimming,
1372 since that memory will immediately be returned to the system.
1375 #define M_TRIM_THRESHOLD -1
1377 #ifndef DEFAULT_TRIM_THRESHOLD
1378 #define DEFAULT_TRIM_THRESHOLD (128 * 1024)
1379 #endif
1382 M_TOP_PAD is the amount of extra `padding' space to allocate or
1383 retain whenever sbrk is called. It is used in two ways internally:
1385 * When sbrk is called to extend the top of the arena to satisfy
1386 a new malloc request, this much padding is added to the sbrk
1387 request.
1389 * When malloc_trim is called automatically from free(),
1390 it is used as the `pad' argument.
1392 In both cases, the actual amount of padding is rounded
1393 so that the end of the arena is always a system page boundary.
1395 The main reason for using padding is to avoid calling sbrk so
1396 often. Having even a small pad greatly reduces the likelihood
1397 that nearly every malloc request during program start-up (or
1398 after trimming) will invoke sbrk, which needlessly wastes
1399 time.
1401 Automatic rounding-up to page-size units is normally sufficient
1402 to avoid measurable overhead, so the default is 0. However, in
1403 systems where sbrk is relatively slow, it can pay to increase
1404 this value, at the expense of carrying around more memory than
1405 the program needs.
1408 #define M_TOP_PAD -2
1410 #ifndef DEFAULT_TOP_PAD
1411 #define DEFAULT_TOP_PAD (0)
1412 #endif
1415 MMAP_THRESHOLD_MAX and _MIN are the bounds on the dynamically
1416 adjusted MMAP_THRESHOLD.
1419 #ifndef DEFAULT_MMAP_THRESHOLD_MIN
1420 #define DEFAULT_MMAP_THRESHOLD_MIN (128 * 1024)
1421 #endif
1423 #ifndef DEFAULT_MMAP_THRESHOLD_MAX
1424 /* For 32-bit platforms we cannot increase the maximum mmap
1425 threshold much because it is also the minimum value for the
1426 maximum heap size and its alignment. Going above 512k (i.e., 1M
1427 for new heaps) wastes too much address space. */
1428 # if __WORDSIZE == 32
1429 # define DEFAULT_MMAP_THRESHOLD_MAX (512 * 1024)
1430 # else
1431 # define DEFAULT_MMAP_THRESHOLD_MAX (4 * 1024 * 1024 * sizeof(long))
1432 # endif
1433 #endif
1436 M_MMAP_THRESHOLD is the request size threshold for using mmap()
1437 to service a request. Requests of at least this size that cannot
1438 be allocated using already-existing space will be serviced via mmap.
1439 (If enough normal freed space already exists it is used instead.)
1441 Using mmap segregates relatively large chunks of memory so that
1442 they can be individually obtained and released from the host
1443 system. A request serviced through mmap is never reused by any
1444 other request (at least not directly; the system may just so
1445 happen to remap successive requests to the same locations).
1447 Segregating space in this way has the benefits that:
1449 1. Mmapped space can ALWAYS be individually released back
1450 to the system, which helps keep the system level memory
1451 demands of a long-lived program low.
1452 2. Mapped memory can never become `locked' between
1453 other chunks, as can happen with normally allocated chunks, which
1454 means that even trimming via malloc_trim would not release them.
1455 3. On some systems with "holes" in address spaces, mmap can obtain
1456 memory that sbrk cannot.
1458 However, it has the disadvantages that:
1460 1. The space cannot be reclaimed, consolidated, and then
1461 used to service later requests, as happens with normal chunks.
1462 2. It can lead to more wastage because of mmap page alignment
1463 requirements
1464 3. It causes malloc performance to be more dependent on host
1465 system memory management support routines which may vary in
1466 implementation quality and may impose arbitrary
1467 limitations. Generally, servicing a request via normal
1468 malloc steps is faster than going through a system's mmap.
1470 The advantages of mmap nearly always outweigh disadvantages for
1471 "large" chunks, but the value of "large" varies across systems. The
1472 default is an empirically derived value that works well in most
1473 systems.
1476 Update in 2006:
1477 The above was written in 2001. Since then the world has changed a lot.
1478 Memory got bigger. Applications got bigger. The virtual address space
1479 layout in 32 bit linux changed.
1481 In the new situation, brk() and mmap space is shared and there are no
1482 artificial limits on brk size imposed by the kernel. What is more,
1483 applications have started using transient allocations larger than the
1484 128Kb as was imagined in 2001.
1486 The price for mmap is also high now; each time glibc mmaps from the
1487 kernel, the kernel is forced to zero out the memory it gives to the
1488 application. Zeroing memory is expensive and eats a lot of cache and
1489 memory bandwidth. This has nothing to do with the efficiency of the
1490 virtual memory system, by doing mmap the kernel just has no choice but
1491 to zero.
1493 In 2001, the kernel had a maximum size for brk() which was about 800
1494 megabytes on 32 bit x86, at that point brk() would hit the first
1495 mmaped shared libaries and couldn't expand anymore. With current 2.6
1496 kernels, the VA space layout is different and brk() and mmap
1497 both can span the entire heap at will.
1499 Rather than using a static threshold for the brk/mmap tradeoff,
1500 we are now using a simple dynamic one. The goal is still to avoid
1501 fragmentation. The old goals we kept are
1502 1) try to get the long lived large allocations to use mmap()
1503 2) really large allocations should always use mmap()
1504 and we're adding now:
1505 3) transient allocations should use brk() to avoid forcing the kernel
1506 having to zero memory over and over again
1508 The implementation works with a sliding threshold, which is by default
1509 limited to go between 128Kb and 32Mb (64Mb for 64 bitmachines) and starts
1510 out at 128Kb as per the 2001 default.
1512 This allows us to satisfy requirement 1) under the assumption that long
1513 lived allocations are made early in the process' lifespan, before it has
1514 started doing dynamic allocations of the same size (which will
1515 increase the threshold).
1517 The upperbound on the threshold satisfies requirement 2)
1519 The threshold goes up in value when the application frees memory that was
1520 allocated with the mmap allocator. The idea is that once the application
1521 starts freeing memory of a certain size, it's highly probable that this is
1522 a size the application uses for transient allocations. This estimator
1523 is there to satisfy the new third requirement.
1527 #define M_MMAP_THRESHOLD -3
1529 #ifndef DEFAULT_MMAP_THRESHOLD
1530 #define DEFAULT_MMAP_THRESHOLD DEFAULT_MMAP_THRESHOLD_MIN
1531 #endif
1534 M_MMAP_MAX is the maximum number of requests to simultaneously
1535 service using mmap. This parameter exists because
1536 some systems have a limited number of internal tables for
1537 use by mmap, and using more than a few of them may degrade
1538 performance.
1540 The default is set to a value that serves only as a safeguard.
1541 Setting to 0 disables use of mmap for servicing large requests. If
1542 HAVE_MMAP is not set, the default value is 0, and attempts to set it
1543 to non-zero values in mallopt will fail.
1546 #define M_MMAP_MAX -4
1548 #ifndef DEFAULT_MMAP_MAX
1549 #if HAVE_MMAP
1550 #define DEFAULT_MMAP_MAX (65536)
1551 #else
1552 #define DEFAULT_MMAP_MAX (0)
1553 #endif
1554 #endif
1556 #ifdef __cplusplus
1557 } /* end of extern "C" */
1558 #endif
1560 #include <malloc.h>
1562 #ifndef BOUNDED_N
1563 #define BOUNDED_N(ptr, sz) (ptr)
1564 #endif
1565 #ifndef RETURN_ADDRESS
1566 #define RETURN_ADDRESS(X_) (NULL)
1567 #endif
1569 /* On some platforms we can compile internal, not exported functions better.
1570 Let the environment provide a macro and define it to be empty if it
1571 is not available. */
1572 #ifndef internal_function
1573 # define internal_function
1574 #endif
1576 /* Forward declarations. */
1577 struct malloc_chunk;
1578 typedef struct malloc_chunk* mchunkptr;
1580 /* Internal routines. */
1582 #if __STD_C
1584 static Void_t* _int_malloc(mstate, size_t);
1585 static void _int_free(mstate, mchunkptr);
1586 static Void_t* _int_realloc(mstate, mchunkptr, INTERNAL_SIZE_T);
1587 static Void_t* _int_memalign(mstate, size_t, size_t);
1588 static Void_t* _int_valloc(mstate, size_t);
1589 static Void_t* _int_pvalloc(mstate, size_t);
1590 /*static Void_t* cALLOc(size_t, size_t);*/
1591 #ifndef _LIBC
1592 static Void_t** _int_icalloc(mstate, size_t, size_t, Void_t**);
1593 static Void_t** _int_icomalloc(mstate, size_t, size_t*, Void_t**);
1594 #endif
1595 static int mTRIm(mstate, size_t);
1596 static size_t mUSABLe(Void_t*);
1597 static void mSTATs(void);
1598 static int mALLOPt(int, int);
1599 static struct mallinfo mALLINFo(mstate);
1600 static void malloc_printerr(int action, const char *str, void *ptr);
1602 static Void_t* internal_function mem2mem_check(Void_t *p, size_t sz);
1603 static int internal_function top_check(void);
1604 static void internal_function munmap_chunk(mchunkptr p);
1605 #if HAVE_MREMAP
1606 static mchunkptr internal_function mremap_chunk(mchunkptr p, size_t new_size);
1607 #endif
1609 static Void_t* malloc_check(size_t sz, const Void_t *caller);
1610 static void free_check(Void_t* mem, const Void_t *caller);
1611 static Void_t* realloc_check(Void_t* oldmem, size_t bytes,
1612 const Void_t *caller);
1613 static Void_t* memalign_check(size_t alignment, size_t bytes,
1614 const Void_t *caller);
1615 #ifndef NO_THREADS
1616 # ifdef _LIBC
1617 # if USE___THREAD || !defined SHARED
1618 /* These routines are never needed in this configuration. */
1619 # define NO_STARTER
1620 # endif
1621 # endif
1622 # ifdef NO_STARTER
1623 # undef NO_STARTER
1624 # else
1625 static Void_t* malloc_starter(size_t sz, const Void_t *caller);
1626 static Void_t* memalign_starter(size_t aln, size_t sz, const Void_t *caller);
1627 static void free_starter(Void_t* mem, const Void_t *caller);
1628 # endif
1629 static Void_t* malloc_atfork(size_t sz, const Void_t *caller);
1630 static void free_atfork(Void_t* mem, const Void_t *caller);
1631 #endif
1633 #else
1635 static Void_t* _int_malloc();
1636 static void _int_free();
1637 static Void_t* _int_realloc();
1638 static Void_t* _int_memalign();
1639 static Void_t* _int_valloc();
1640 static Void_t* _int_pvalloc();
1641 /*static Void_t* cALLOc();*/
1642 static Void_t** _int_icalloc();
1643 static Void_t** _int_icomalloc();
1644 static int mTRIm();
1645 static size_t mUSABLe();
1646 static void mSTATs();
1647 static int mALLOPt();
1648 static struct mallinfo mALLINFo();
1650 #endif
1655 /* ------------- Optional versions of memcopy ---------------- */
1658 #if USE_MEMCPY
1661 Note: memcpy is ONLY invoked with non-overlapping regions,
1662 so the (usually slower) memmove is not needed.
1665 #define MALLOC_COPY(dest, src, nbytes) memcpy(dest, src, nbytes)
1666 #define MALLOC_ZERO(dest, nbytes) memset(dest, 0, nbytes)
1668 #else /* !USE_MEMCPY */
1670 /* Use Duff's device for good zeroing/copying performance. */
1672 #define MALLOC_ZERO(charp, nbytes) \
1673 do { \
1674 INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \
1675 unsigned long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T); \
1676 long mcn; \
1677 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
1678 switch (mctmp) { \
1679 case 0: for(;;) { *mzp++ = 0; \
1680 case 7: *mzp++ = 0; \
1681 case 6: *mzp++ = 0; \
1682 case 5: *mzp++ = 0; \
1683 case 4: *mzp++ = 0; \
1684 case 3: *mzp++ = 0; \
1685 case 2: *mzp++ = 0; \
1686 case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \
1688 } while(0)
1690 #define MALLOC_COPY(dest,src,nbytes) \
1691 do { \
1692 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \
1693 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \
1694 unsigned long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T); \
1695 long mcn; \
1696 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
1697 switch (mctmp) { \
1698 case 0: for(;;) { *mcdst++ = *mcsrc++; \
1699 case 7: *mcdst++ = *mcsrc++; \
1700 case 6: *mcdst++ = *mcsrc++; \
1701 case 5: *mcdst++ = *mcsrc++; \
1702 case 4: *mcdst++ = *mcsrc++; \
1703 case 3: *mcdst++ = *mcsrc++; \
1704 case 2: *mcdst++ = *mcsrc++; \
1705 case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \
1707 } while(0)
1709 #endif
1711 /* ------------------ MMAP support ------------------ */
1714 #if HAVE_MMAP
1716 #include <fcntl.h>
1717 #ifndef LACKS_SYS_MMAN_H
1718 #include <sys/mman.h>
1719 #endif
1721 #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
1722 # define MAP_ANONYMOUS MAP_ANON
1723 #endif
1724 #if !defined(MAP_FAILED)
1725 # define MAP_FAILED ((char*)-1)
1726 #endif
1728 #ifndef MAP_NORESERVE
1729 # ifdef MAP_AUTORESRV
1730 # define MAP_NORESERVE MAP_AUTORESRV
1731 # else
1732 # define MAP_NORESERVE 0
1733 # endif
1734 #endif
1737 Nearly all versions of mmap support MAP_ANONYMOUS,
1738 so the following is unlikely to be needed, but is
1739 supplied just in case.
1742 #ifndef MAP_ANONYMOUS
1744 static int dev_zero_fd = -1; /* Cached file descriptor for /dev/zero. */
1746 #define MMAP(addr, size, prot, flags) ((dev_zero_fd < 0) ? \
1747 (dev_zero_fd = open("/dev/zero", O_RDWR), \
1748 mmap((addr), (size), (prot), (flags), dev_zero_fd, 0)) : \
1749 mmap((addr), (size), (prot), (flags), dev_zero_fd, 0))
1751 #else
1753 #define MMAP(addr, size, prot, flags) \
1754 (mmap((addr), (size), (prot), (flags)|MAP_ANONYMOUS, -1, 0))
1756 #endif
1759 #endif /* HAVE_MMAP */
1763 ----------------------- Chunk representations -----------------------
1768 This struct declaration is misleading (but accurate and necessary).
1769 It declares a "view" into memory allowing access to necessary
1770 fields at known offsets from a given base. See explanation below.
1773 struct malloc_chunk {
1775 INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */
1776 INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */
1778 struct malloc_chunk* fd; /* double links -- used only if free. */
1779 struct malloc_chunk* bk;
1781 /* Only used for large blocks: pointer to next larger size. */
1782 struct malloc_chunk* fd_nextsize; /* double links -- used only if free. */
1783 struct malloc_chunk* bk_nextsize;
1788 malloc_chunk details:
1790 (The following includes lightly edited explanations by Colin Plumb.)
1792 Chunks of memory are maintained using a `boundary tag' method as
1793 described in e.g., Knuth or Standish. (See the paper by Paul
1794 Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
1795 survey of such techniques.) Sizes of free chunks are stored both
1796 in the front of each chunk and at the end. This makes
1797 consolidating fragmented chunks into bigger chunks very fast. The
1798 size fields also hold bits representing whether chunks are free or
1799 in use.
1801 An allocated chunk looks like this:
1804 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1805 | Size of previous chunk, if allocated | |
1806 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1807 | Size of chunk, in bytes |M|P|
1808 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1809 | User data starts here... .
1811 . (malloc_usable_size() bytes) .
1813 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1814 | Size of chunk |
1815 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1818 Where "chunk" is the front of the chunk for the purpose of most of
1819 the malloc code, but "mem" is the pointer that is returned to the
1820 user. "Nextchunk" is the beginning of the next contiguous chunk.
1822 Chunks always begin on even word boundries, so the mem portion
1823 (which is returned to the user) is also on an even word boundary, and
1824 thus at least double-word aligned.
1826 Free chunks are stored in circular doubly-linked lists, and look like this:
1828 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1829 | Size of previous chunk |
1830 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1831 `head:' | Size of chunk, in bytes |P|
1832 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1833 | Forward pointer to next chunk in list |
1834 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1835 | Back pointer to previous chunk in list |
1836 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1837 | Unused space (may be 0 bytes long) .
1840 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1841 `foot:' | Size of chunk, in bytes |
1842 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1844 The P (PREV_INUSE) bit, stored in the unused low-order bit of the
1845 chunk size (which is always a multiple of two words), is an in-use
1846 bit for the *previous* chunk. If that bit is *clear*, then the
1847 word before the current chunk size contains the previous chunk
1848 size, and can be used to find the front of the previous chunk.
1849 The very first chunk allocated always has this bit set,
1850 preventing access to non-existent (or non-owned) memory. If
1851 prev_inuse is set for any given chunk, then you CANNOT determine
1852 the size of the previous chunk, and might even get a memory
1853 addressing fault when trying to do so.
1855 Note that the `foot' of the current chunk is actually represented
1856 as the prev_size of the NEXT chunk. This makes it easier to
1857 deal with alignments etc but can be very confusing when trying
1858 to extend or adapt this code.
1860 The two exceptions to all this are
1862 1. The special chunk `top' doesn't bother using the
1863 trailing size field since there is no next contiguous chunk
1864 that would have to index off it. After initialization, `top'
1865 is forced to always exist. If it would become less than
1866 MINSIZE bytes long, it is replenished.
1868 2. Chunks allocated via mmap, which have the second-lowest-order
1869 bit M (IS_MMAPPED) set in their size fields. Because they are
1870 allocated one-by-one, each must contain its own trailing size field.
1875 ---------- Size and alignment checks and conversions ----------
1878 /* conversion from malloc headers to user pointers, and back */
1880 #define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ))
1881 #define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))
1883 /* The smallest possible chunk */
1884 #define MIN_CHUNK_SIZE (offsetof(struct malloc_chunk, fd_nextsize))
1886 /* The smallest size we can malloc is an aligned minimal chunk */
1888 #define MINSIZE \
1889 (unsigned long)(((MIN_CHUNK_SIZE+MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK))
1891 /* Check if m has acceptable alignment */
1893 #define aligned_OK(m) (((unsigned long)(m) & MALLOC_ALIGN_MASK) == 0)
1895 #define misaligned_chunk(p) \
1896 ((uintptr_t)(MALLOC_ALIGNMENT == 2 * SIZE_SZ ? (p) : chunk2mem (p)) \
1897 & MALLOC_ALIGN_MASK)
1901 Check if a request is so large that it would wrap around zero when
1902 padded and aligned. To simplify some other code, the bound is made
1903 low enough so that adding MINSIZE will also not wrap around zero.
1906 #define REQUEST_OUT_OF_RANGE(req) \
1907 ((unsigned long)(req) >= \
1908 (unsigned long)(INTERNAL_SIZE_T)(-2 * MINSIZE))
1910 /* pad request bytes into a usable size -- internal version */
1912 #define request2size(req) \
1913 (((req) + SIZE_SZ + MALLOC_ALIGN_MASK < MINSIZE) ? \
1914 MINSIZE : \
1915 ((req) + SIZE_SZ + MALLOC_ALIGN_MASK) & ~MALLOC_ALIGN_MASK)
1917 /* Same, except also perform argument check */
1919 #define checked_request2size(req, sz) \
1920 if (REQUEST_OUT_OF_RANGE(req)) { \
1921 MALLOC_FAILURE_ACTION; \
1922 return 0; \
1924 (sz) = request2size(req);
1927 --------------- Physical chunk operations ---------------
1931 /* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
1932 #define PREV_INUSE 0x1
1934 /* extract inuse bit of previous chunk */
1935 #define prev_inuse(p) ((p)->size & PREV_INUSE)
1938 /* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
1939 #define IS_MMAPPED 0x2
1941 /* check for mmap()'ed chunk */
1942 #define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED)
1945 /* size field is or'ed with NON_MAIN_ARENA if the chunk was obtained
1946 from a non-main arena. This is only set immediately before handing
1947 the chunk to the user, if necessary. */
1948 #define NON_MAIN_ARENA 0x4
1950 /* check for chunk from non-main arena */
1951 #define chunk_non_main_arena(p) ((p)->size & NON_MAIN_ARENA)
1955 Bits to mask off when extracting size
1957 Note: IS_MMAPPED is intentionally not masked off from size field in
1958 macros for which mmapped chunks should never be seen. This should
1959 cause helpful core dumps to occur if it is tried by accident by
1960 people extending or adapting this malloc.
1962 #define SIZE_BITS (PREV_INUSE|IS_MMAPPED|NON_MAIN_ARENA)
1964 /* Get size, ignoring use bits */
1965 #define chunksize(p) ((p)->size & ~(SIZE_BITS))
1968 /* Ptr to next physical malloc_chunk. */
1969 #define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~SIZE_BITS) ))
1971 /* Ptr to previous physical malloc_chunk */
1972 #define prev_chunk(p) ((mchunkptr)( ((char*)(p)) - ((p)->prev_size) ))
1974 /* Treat space at ptr + offset as a chunk */
1975 #define chunk_at_offset(p, s) ((mchunkptr)(((char*)(p)) + (s)))
1977 /* extract p's inuse bit */
1978 #define inuse(p)\
1979 ((((mchunkptr)(((char*)(p))+((p)->size & ~SIZE_BITS)))->size) & PREV_INUSE)
1981 /* set/clear chunk as being inuse without otherwise disturbing */
1982 #define set_inuse(p)\
1983 ((mchunkptr)(((char*)(p)) + ((p)->size & ~SIZE_BITS)))->size |= PREV_INUSE
1985 #define clear_inuse(p)\
1986 ((mchunkptr)(((char*)(p)) + ((p)->size & ~SIZE_BITS)))->size &= ~(PREV_INUSE)
1989 /* check/set/clear inuse bits in known places */
1990 #define inuse_bit_at_offset(p, s)\
1991 (((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE)
1993 #define set_inuse_bit_at_offset(p, s)\
1994 (((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE)
1996 #define clear_inuse_bit_at_offset(p, s)\
1997 (((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE))
2000 /* Set size at head, without disturbing its use bit */
2001 #define set_head_size(p, s) ((p)->size = (((p)->size & SIZE_BITS) | (s)))
2003 /* Set size/use field */
2004 #define set_head(p, s) ((p)->size = (s))
2006 /* Set size at footer (only when chunk is not in use) */
2007 #define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_size = (s))
2011 -------------------- Internal data structures --------------------
2013 All internal state is held in an instance of malloc_state defined
2014 below. There are no other static variables, except in two optional
2015 cases:
2016 * If USE_MALLOC_LOCK is defined, the mALLOC_MUTEx declared above.
2017 * If HAVE_MMAP is true, but mmap doesn't support
2018 MAP_ANONYMOUS, a dummy file descriptor for mmap.
2020 Beware of lots of tricks that minimize the total bookkeeping space
2021 requirements. The result is a little over 1K bytes (for 4byte
2022 pointers and size_t.)
2026 Bins
2028 An array of bin headers for free chunks. Each bin is doubly
2029 linked. The bins are approximately proportionally (log) spaced.
2030 There are a lot of these bins (128). This may look excessive, but
2031 works very well in practice. Most bins hold sizes that are
2032 unusual as malloc request sizes, but are more usual for fragments
2033 and consolidated sets of chunks, which is what these bins hold, so
2034 they can be found quickly. All procedures maintain the invariant
2035 that no consolidated chunk physically borders another one, so each
2036 chunk in a list is known to be preceeded and followed by either
2037 inuse chunks or the ends of memory.
2039 Chunks in bins are kept in size order, with ties going to the
2040 approximately least recently used chunk. Ordering isn't needed
2041 for the small bins, which all contain the same-sized chunks, but
2042 facilitates best-fit allocation for larger chunks. These lists
2043 are just sequential. Keeping them in order almost never requires
2044 enough traversal to warrant using fancier ordered data
2045 structures.
2047 Chunks of the same size are linked with the most
2048 recently freed at the front, and allocations are taken from the
2049 back. This results in LRU (FIFO) allocation order, which tends
2050 to give each chunk an equal opportunity to be consolidated with
2051 adjacent freed chunks, resulting in larger free chunks and less
2052 fragmentation.
2054 To simplify use in double-linked lists, each bin header acts
2055 as a malloc_chunk. This avoids special-casing for headers.
2056 But to conserve space and improve locality, we allocate
2057 only the fd/bk pointers of bins, and then use repositioning tricks
2058 to treat these as the fields of a malloc_chunk*.
2061 typedef struct malloc_chunk* mbinptr;
2063 /* addressing -- note that bin_at(0) does not exist */
2064 #define bin_at(m, i) \
2065 (mbinptr) (((char *) &((m)->bins[((i) - 1) * 2])) \
2066 - offsetof (struct malloc_chunk, fd))
2068 /* analog of ++bin */
2069 #define next_bin(b) ((mbinptr)((char*)(b) + (sizeof(mchunkptr)<<1)))
2071 /* Reminders about list directionality within bins */
2072 #define first(b) ((b)->fd)
2073 #define last(b) ((b)->bk)
2075 /* Take a chunk off a bin list */
2076 #define unlink(P, BK, FD) { \
2077 FD = P->fd; \
2078 BK = P->bk; \
2079 if (__builtin_expect (FD->bk != P || BK->fd != P, 0)) \
2080 malloc_printerr (check_action, "corrupted double-linked list", P); \
2081 else { \
2082 FD->bk = BK; \
2083 BK->fd = FD; \
2084 if (!in_smallbin_range (P->size) \
2085 && __builtin_expect (P->fd_nextsize != NULL, 0)) { \
2086 assert (P->fd_nextsize->bk_nextsize == P); \
2087 assert (P->bk_nextsize->fd_nextsize == P); \
2088 if (FD->fd_nextsize == NULL) { \
2089 if (P->fd_nextsize == P) \
2090 FD->fd_nextsize = FD->bk_nextsize = FD; \
2091 else { \
2092 FD->fd_nextsize = P->fd_nextsize; \
2093 FD->bk_nextsize = P->bk_nextsize; \
2094 P->fd_nextsize->bk_nextsize = FD; \
2095 P->bk_nextsize->fd_nextsize = FD; \
2097 } else { \
2098 P->fd_nextsize->bk_nextsize = P->bk_nextsize; \
2099 P->bk_nextsize->fd_nextsize = P->fd_nextsize; \
2106 Indexing
2108 Bins for sizes < 512 bytes contain chunks of all the same size, spaced
2109 8 bytes apart. Larger bins are approximately logarithmically spaced:
2111 64 bins of size 8
2112 32 bins of size 64
2113 16 bins of size 512
2114 8 bins of size 4096
2115 4 bins of size 32768
2116 2 bins of size 262144
2117 1 bin of size what's left
2119 There is actually a little bit of slop in the numbers in bin_index
2120 for the sake of speed. This makes no difference elsewhere.
2122 The bins top out around 1MB because we expect to service large
2123 requests via mmap.
2126 #define NBINS 128
2127 #define NSMALLBINS 64
2128 #define SMALLBIN_WIDTH MALLOC_ALIGNMENT
2129 #define MIN_LARGE_SIZE (NSMALLBINS * SMALLBIN_WIDTH)
2131 #define in_smallbin_range(sz) \
2132 ((unsigned long)(sz) < (unsigned long)MIN_LARGE_SIZE)
2134 #define smallbin_index(sz) \
2135 (SMALLBIN_WIDTH == 16 ? (((unsigned)(sz)) >> 4) : (((unsigned)(sz)) >> 3))
2137 #define largebin_index_32(sz) \
2138 (((((unsigned long)(sz)) >> 6) <= 38)? 56 + (((unsigned long)(sz)) >> 6): \
2139 ((((unsigned long)(sz)) >> 9) <= 20)? 91 + (((unsigned long)(sz)) >> 9): \
2140 ((((unsigned long)(sz)) >> 12) <= 10)? 110 + (((unsigned long)(sz)) >> 12): \
2141 ((((unsigned long)(sz)) >> 15) <= 4)? 119 + (((unsigned long)(sz)) >> 15): \
2142 ((((unsigned long)(sz)) >> 18) <= 2)? 124 + (((unsigned long)(sz)) >> 18): \
2143 126)
2145 // XXX It remains to be seen whether it is good to keep the widths of
2146 // XXX the buckets the same or whether it should be scaled by a factor
2147 // XXX of two as well.
2148 #define largebin_index_64(sz) \
2149 (((((unsigned long)(sz)) >> 6) <= 48)? 48 + (((unsigned long)(sz)) >> 6): \
2150 ((((unsigned long)(sz)) >> 9) <= 20)? 91 + (((unsigned long)(sz)) >> 9): \
2151 ((((unsigned long)(sz)) >> 12) <= 10)? 110 + (((unsigned long)(sz)) >> 12): \
2152 ((((unsigned long)(sz)) >> 15) <= 4)? 119 + (((unsigned long)(sz)) >> 15): \
2153 ((((unsigned long)(sz)) >> 18) <= 2)? 124 + (((unsigned long)(sz)) >> 18): \
2154 126)
2156 #define largebin_index(sz) \
2157 (SIZE_SZ == 8 ? largebin_index_64 (sz) : largebin_index_32 (sz))
2159 #define bin_index(sz) \
2160 ((in_smallbin_range(sz)) ? smallbin_index(sz) : largebin_index(sz))
2164 Unsorted chunks
2166 All remainders from chunk splits, as well as all returned chunks,
2167 are first placed in the "unsorted" bin. They are then placed
2168 in regular bins after malloc gives them ONE chance to be used before
2169 binning. So, basically, the unsorted_chunks list acts as a queue,
2170 with chunks being placed on it in free (and malloc_consolidate),
2171 and taken off (to be either used or placed in bins) in malloc.
2173 The NON_MAIN_ARENA flag is never set for unsorted chunks, so it
2174 does not have to be taken into account in size comparisons.
2177 /* The otherwise unindexable 1-bin is used to hold unsorted chunks. */
2178 #define unsorted_chunks(M) (bin_at(M, 1))
2183 The top-most available chunk (i.e., the one bordering the end of
2184 available memory) is treated specially. It is never included in
2185 any bin, is used only if no other chunk is available, and is
2186 released back to the system if it is very large (see
2187 M_TRIM_THRESHOLD). Because top initially
2188 points to its own bin with initial zero size, thus forcing
2189 extension on the first malloc request, we avoid having any special
2190 code in malloc to check whether it even exists yet. But we still
2191 need to do so when getting memory from system, so we make
2192 initial_top treat the bin as a legal but unusable chunk during the
2193 interval between initialization and the first call to
2194 sYSMALLOc. (This is somewhat delicate, since it relies on
2195 the 2 preceding words to be zero during this interval as well.)
2198 /* Conveniently, the unsorted bin can be used as dummy top on first call */
2199 #define initial_top(M) (unsorted_chunks(M))
2202 Binmap
2204 To help compensate for the large number of bins, a one-level index
2205 structure is used for bin-by-bin searching. `binmap' is a
2206 bitvector recording whether bins are definitely empty so they can
2207 be skipped over during during traversals. The bits are NOT always
2208 cleared as soon as bins are empty, but instead only
2209 when they are noticed to be empty during traversal in malloc.
2212 /* Conservatively use 32 bits per map word, even if on 64bit system */
2213 #define BINMAPSHIFT 5
2214 #define BITSPERMAP (1U << BINMAPSHIFT)
2215 #define BINMAPSIZE (NBINS / BITSPERMAP)
2217 #define idx2block(i) ((i) >> BINMAPSHIFT)
2218 #define idx2bit(i) ((1U << ((i) & ((1U << BINMAPSHIFT)-1))))
2220 #define mark_bin(m,i) ((m)->binmap[idx2block(i)] |= idx2bit(i))
2221 #define unmark_bin(m,i) ((m)->binmap[idx2block(i)] &= ~(idx2bit(i)))
2222 #define get_binmap(m,i) ((m)->binmap[idx2block(i)] & idx2bit(i))
2225 Fastbins
2227 An array of lists holding recently freed small chunks. Fastbins
2228 are not doubly linked. It is faster to single-link them, and
2229 since chunks are never removed from the middles of these lists,
2230 double linking is not necessary. Also, unlike regular bins, they
2231 are not even processed in FIFO order (they use faster LIFO) since
2232 ordering doesn't much matter in the transient contexts in which
2233 fastbins are normally used.
2235 Chunks in fastbins keep their inuse bit set, so they cannot
2236 be consolidated with other free chunks. malloc_consolidate
2237 releases all chunks in fastbins and consolidates them with
2238 other free chunks.
2241 typedef struct malloc_chunk* mfastbinptr;
2243 /* offset 2 to use otherwise unindexable first 2 bins */
2244 #define fastbin_index(sz) ((((unsigned int)(sz)) >> 3) - 2)
2246 /* The maximum fastbin request size we support */
2247 #define MAX_FAST_SIZE 80
2249 #define NFASTBINS (fastbin_index(request2size(MAX_FAST_SIZE))+1)
2252 FASTBIN_CONSOLIDATION_THRESHOLD is the size of a chunk in free()
2253 that triggers automatic consolidation of possibly-surrounding
2254 fastbin chunks. This is a heuristic, so the exact value should not
2255 matter too much. It is defined at half the default trim threshold as a
2256 compromise heuristic to only attempt consolidation if it is likely
2257 to lead to trimming. However, it is not dynamically tunable, since
2258 consolidation reduces fragmentation surrounding large chunks even
2259 if trimming is not used.
2262 #define FASTBIN_CONSOLIDATION_THRESHOLD (65536UL)
2265 Since the lowest 2 bits in max_fast don't matter in size comparisons,
2266 they are used as flags.
2270 FASTCHUNKS_BIT held in max_fast indicates that there are probably
2271 some fastbin chunks. It is set true on entering a chunk into any
2272 fastbin, and cleared only in malloc_consolidate.
2274 The truth value is inverted so that have_fastchunks will be true
2275 upon startup (since statics are zero-filled), simplifying
2276 initialization checks.
2279 #define FASTCHUNKS_BIT (1U)
2281 #define have_fastchunks(M) (((M)->flags & FASTCHUNKS_BIT) == 0)
2282 #define clear_fastchunks(M) ((M)->flags |= FASTCHUNKS_BIT)
2283 #define set_fastchunks(M) ((M)->flags &= ~FASTCHUNKS_BIT)
2286 NONCONTIGUOUS_BIT indicates that MORECORE does not return contiguous
2287 regions. Otherwise, contiguity is exploited in merging together,
2288 when possible, results from consecutive MORECORE calls.
2290 The initial value comes from MORECORE_CONTIGUOUS, but is
2291 changed dynamically if mmap is ever used as an sbrk substitute.
2294 #define NONCONTIGUOUS_BIT (2U)
2296 #define contiguous(M) (((M)->flags & NONCONTIGUOUS_BIT) == 0)
2297 #define noncontiguous(M) (((M)->flags & NONCONTIGUOUS_BIT) != 0)
2298 #define set_noncontiguous(M) ((M)->flags |= NONCONTIGUOUS_BIT)
2299 #define set_contiguous(M) ((M)->flags &= ~NONCONTIGUOUS_BIT)
2302 Set value of max_fast.
2303 Use impossibly small value if 0.
2304 Precondition: there are no existing fastbin chunks.
2305 Setting the value clears fastchunk bit but preserves noncontiguous bit.
2308 #define set_max_fast(s) \
2309 global_max_fast = ((s) == 0)? SMALLBIN_WIDTH: request2size(s)
2310 #define get_max_fast() global_max_fast
2314 ----------- Internal state representation and initialization -----------
2317 struct malloc_state {
2318 /* Serialize access. */
2319 mutex_t mutex;
2321 /* Flags (formerly in max_fast). */
2322 int flags;
2324 #if THREAD_STATS
2325 /* Statistics for locking. Only used if THREAD_STATS is defined. */
2326 long stat_lock_direct, stat_lock_loop, stat_lock_wait;
2327 #endif
2329 /* Fastbins */
2330 mfastbinptr fastbins[NFASTBINS];
2332 /* Base of the topmost chunk -- not otherwise kept in a bin */
2333 mchunkptr top;
2335 /* The remainder from the most recent split of a small request */
2336 mchunkptr last_remainder;
2338 /* Normal bins packed as described above */
2339 mchunkptr bins[NBINS * 2 - 2];
2341 /* Bitmap of bins */
2342 unsigned int binmap[BINMAPSIZE];
2344 /* Linked list */
2345 struct malloc_state *next;
2347 /* Memory allocated from the system in this arena. */
2348 INTERNAL_SIZE_T system_mem;
2349 INTERNAL_SIZE_T max_system_mem;
2352 struct malloc_par {
2353 /* Tunable parameters */
2354 unsigned long trim_threshold;
2355 INTERNAL_SIZE_T top_pad;
2356 INTERNAL_SIZE_T mmap_threshold;
2358 /* Memory map support */
2359 int n_mmaps;
2360 int n_mmaps_max;
2361 int max_n_mmaps;
2362 /* the mmap_threshold is dynamic, until the user sets
2363 it manually, at which point we need to disable any
2364 dynamic behavior. */
2365 int no_dyn_threshold;
2367 /* Cache malloc_getpagesize */
2368 unsigned int pagesize;
2370 /* Statistics */
2371 INTERNAL_SIZE_T mmapped_mem;
2372 /*INTERNAL_SIZE_T sbrked_mem;*/
2373 /*INTERNAL_SIZE_T max_sbrked_mem;*/
2374 INTERNAL_SIZE_T max_mmapped_mem;
2375 INTERNAL_SIZE_T max_total_mem; /* only kept for NO_THREADS */
2377 /* First address handed out by MORECORE/sbrk. */
2378 char* sbrk_base;
2381 /* There are several instances of this struct ("arenas") in this
2382 malloc. If you are adapting this malloc in a way that does NOT use
2383 a static or mmapped malloc_state, you MUST explicitly zero-fill it
2384 before using. This malloc relies on the property that malloc_state
2385 is initialized to all zeroes (as is true of C statics). */
2387 static struct malloc_state main_arena;
2389 /* There is only one instance of the malloc parameters. */
2391 static struct malloc_par mp_;
2394 /* Maximum size of memory handled in fastbins. */
2395 static INTERNAL_SIZE_T global_max_fast;
2398 Initialize a malloc_state struct.
2400 This is called only from within malloc_consolidate, which needs
2401 be called in the same contexts anyway. It is never called directly
2402 outside of malloc_consolidate because some optimizing compilers try
2403 to inline it at all call points, which turns out not to be an
2404 optimization at all. (Inlining it in malloc_consolidate is fine though.)
2407 #if __STD_C
2408 static void malloc_init_state(mstate av)
2409 #else
2410 static void malloc_init_state(av) mstate av;
2411 #endif
2413 int i;
2414 mbinptr bin;
2416 /* Establish circular links for normal bins */
2417 for (i = 1; i < NBINS; ++i) {
2418 bin = bin_at(av,i);
2419 bin->fd = bin->bk = bin;
2422 #if MORECORE_CONTIGUOUS
2423 if (av != &main_arena)
2424 #endif
2425 set_noncontiguous(av);
2426 if (av == &main_arena)
2427 set_max_fast(DEFAULT_MXFAST);
2428 av->flags |= FASTCHUNKS_BIT;
2430 av->top = initial_top(av);
2434 Other internal utilities operating on mstates
2437 #if __STD_C
2438 static Void_t* sYSMALLOc(INTERNAL_SIZE_T, mstate);
2439 static int sYSTRIm(size_t, mstate);
2440 static void malloc_consolidate(mstate);
2441 #ifndef _LIBC
2442 static Void_t** iALLOc(mstate, size_t, size_t*, int, Void_t**);
2443 #endif
2444 #else
2445 static Void_t* sYSMALLOc();
2446 static int sYSTRIm();
2447 static void malloc_consolidate();
2448 static Void_t** iALLOc();
2449 #endif
2452 /* -------------- Early definitions for debugging hooks ---------------- */
2454 /* Define and initialize the hook variables. These weak definitions must
2455 appear before any use of the variables in a function (arena.c uses one). */
2456 #ifndef weak_variable
2457 #ifndef _LIBC
2458 #define weak_variable /**/
2459 #else
2460 /* In GNU libc we want the hook variables to be weak definitions to
2461 avoid a problem with Emacs. */
2462 #define weak_variable weak_function
2463 #endif
2464 #endif
2466 /* Forward declarations. */
2467 static Void_t* malloc_hook_ini __MALLOC_P ((size_t sz,
2468 const __malloc_ptr_t caller));
2469 static Void_t* realloc_hook_ini __MALLOC_P ((Void_t* ptr, size_t sz,
2470 const __malloc_ptr_t caller));
2471 static Void_t* memalign_hook_ini __MALLOC_P ((size_t alignment, size_t sz,
2472 const __malloc_ptr_t caller));
2474 void weak_variable (*__malloc_initialize_hook) (void) = NULL;
2475 void weak_variable (*__free_hook) (__malloc_ptr_t __ptr,
2476 const __malloc_ptr_t) = NULL;
2477 __malloc_ptr_t weak_variable (*__malloc_hook)
2478 (size_t __size, const __malloc_ptr_t) = malloc_hook_ini;
2479 __malloc_ptr_t weak_variable (*__realloc_hook)
2480 (__malloc_ptr_t __ptr, size_t __size, const __malloc_ptr_t)
2481 = realloc_hook_ini;
2482 __malloc_ptr_t weak_variable (*__memalign_hook)
2483 (size_t __alignment, size_t __size, const __malloc_ptr_t)
2484 = memalign_hook_ini;
2485 void weak_variable (*__after_morecore_hook) (void) = NULL;
2488 /* ---------------- Error behavior ------------------------------------ */
2490 #ifndef DEFAULT_CHECK_ACTION
2491 #define DEFAULT_CHECK_ACTION 3
2492 #endif
2494 static int check_action = DEFAULT_CHECK_ACTION;
2497 /* ------------------ Testing support ----------------------------------*/
2499 static int perturb_byte;
2501 #define alloc_perturb(p, n) memset (p, (perturb_byte ^ 0xff) & 0xff, n)
2502 #define free_perturb(p, n) memset (p, perturb_byte & 0xff, n)
2505 /* ------------------- Support for multiple arenas -------------------- */
2506 #include "arena.c"
2509 Debugging support
2511 These routines make a number of assertions about the states
2512 of data structures that should be true at all times. If any
2513 are not true, it's very likely that a user program has somehow
2514 trashed memory. (It's also possible that there is a coding error
2515 in malloc. In which case, please report it!)
2518 #if ! MALLOC_DEBUG
2520 #define check_chunk(A,P)
2521 #define check_free_chunk(A,P)
2522 #define check_inuse_chunk(A,P)
2523 #define check_remalloced_chunk(A,P,N)
2524 #define check_malloced_chunk(A,P,N)
2525 #define check_malloc_state(A)
2527 #else
2529 #define check_chunk(A,P) do_check_chunk(A,P)
2530 #define check_free_chunk(A,P) do_check_free_chunk(A,P)
2531 #define check_inuse_chunk(A,P) do_check_inuse_chunk(A,P)
2532 #define check_remalloced_chunk(A,P,N) do_check_remalloced_chunk(A,P,N)
2533 #define check_malloced_chunk(A,P,N) do_check_malloced_chunk(A,P,N)
2534 #define check_malloc_state(A) do_check_malloc_state(A)
2537 Properties of all chunks
2540 #if __STD_C
2541 static void do_check_chunk(mstate av, mchunkptr p)
2542 #else
2543 static void do_check_chunk(av, p) mstate av; mchunkptr p;
2544 #endif
2546 unsigned long sz = chunksize(p);
2547 /* min and max possible addresses assuming contiguous allocation */
2548 char* max_address = (char*)(av->top) + chunksize(av->top);
2549 char* min_address = max_address - av->system_mem;
2551 if (!chunk_is_mmapped(p)) {
2553 /* Has legal address ... */
2554 if (p != av->top) {
2555 if (contiguous(av)) {
2556 assert(((char*)p) >= min_address);
2557 assert(((char*)p + sz) <= ((char*)(av->top)));
2560 else {
2561 /* top size is always at least MINSIZE */
2562 assert((unsigned long)(sz) >= MINSIZE);
2563 /* top predecessor always marked inuse */
2564 assert(prev_inuse(p));
2568 else {
2569 #if HAVE_MMAP
2570 /* address is outside main heap */
2571 if (contiguous(av) && av->top != initial_top(av)) {
2572 assert(((char*)p) < min_address || ((char*)p) >= max_address);
2574 /* chunk is page-aligned */
2575 assert(((p->prev_size + sz) & (mp_.pagesize-1)) == 0);
2576 /* mem is aligned */
2577 assert(aligned_OK(chunk2mem(p)));
2578 #else
2579 /* force an appropriate assert violation if debug set */
2580 assert(!chunk_is_mmapped(p));
2581 #endif
2586 Properties of free chunks
2589 #if __STD_C
2590 static void do_check_free_chunk(mstate av, mchunkptr p)
2591 #else
2592 static void do_check_free_chunk(av, p) mstate av; mchunkptr p;
2593 #endif
2595 INTERNAL_SIZE_T sz = p->size & ~(PREV_INUSE|NON_MAIN_ARENA);
2596 mchunkptr next = chunk_at_offset(p, sz);
2598 do_check_chunk(av, p);
2600 /* Chunk must claim to be free ... */
2601 assert(!inuse(p));
2602 assert (!chunk_is_mmapped(p));
2604 /* Unless a special marker, must have OK fields */
2605 if ((unsigned long)(sz) >= MINSIZE)
2607 assert((sz & MALLOC_ALIGN_MASK) == 0);
2608 assert(aligned_OK(chunk2mem(p)));
2609 /* ... matching footer field */
2610 assert(next->prev_size == sz);
2611 /* ... and is fully consolidated */
2612 assert(prev_inuse(p));
2613 assert (next == av->top || inuse(next));
2615 /* ... and has minimally sane links */
2616 assert(p->fd->bk == p);
2617 assert(p->bk->fd == p);
2619 else /* markers are always of size SIZE_SZ */
2620 assert(sz == SIZE_SZ);
2624 Properties of inuse chunks
2627 #if __STD_C
2628 static void do_check_inuse_chunk(mstate av, mchunkptr p)
2629 #else
2630 static void do_check_inuse_chunk(av, p) mstate av; mchunkptr p;
2631 #endif
2633 mchunkptr next;
2635 do_check_chunk(av, p);
2637 if (chunk_is_mmapped(p))
2638 return; /* mmapped chunks have no next/prev */
2640 /* Check whether it claims to be in use ... */
2641 assert(inuse(p));
2643 next = next_chunk(p);
2645 /* ... and is surrounded by OK chunks.
2646 Since more things can be checked with free chunks than inuse ones,
2647 if an inuse chunk borders them and debug is on, it's worth doing them.
2649 if (!prev_inuse(p)) {
2650 /* Note that we cannot even look at prev unless it is not inuse */
2651 mchunkptr prv = prev_chunk(p);
2652 assert(next_chunk(prv) == p);
2653 do_check_free_chunk(av, prv);
2656 if (next == av->top) {
2657 assert(prev_inuse(next));
2658 assert(chunksize(next) >= MINSIZE);
2660 else if (!inuse(next))
2661 do_check_free_chunk(av, next);
2665 Properties of chunks recycled from fastbins
2668 #if __STD_C
2669 static void do_check_remalloced_chunk(mstate av, mchunkptr p, INTERNAL_SIZE_T s)
2670 #else
2671 static void do_check_remalloced_chunk(av, p, s)
2672 mstate av; mchunkptr p; INTERNAL_SIZE_T s;
2673 #endif
2675 INTERNAL_SIZE_T sz = p->size & ~(PREV_INUSE|NON_MAIN_ARENA);
2677 if (!chunk_is_mmapped(p)) {
2678 assert(av == arena_for_chunk(p));
2679 if (chunk_non_main_arena(p))
2680 assert(av != &main_arena);
2681 else
2682 assert(av == &main_arena);
2685 do_check_inuse_chunk(av, p);
2687 /* Legal size ... */
2688 assert((sz & MALLOC_ALIGN_MASK) == 0);
2689 assert((unsigned long)(sz) >= MINSIZE);
2690 /* ... and alignment */
2691 assert(aligned_OK(chunk2mem(p)));
2692 /* chunk is less than MINSIZE more than request */
2693 assert((long)(sz) - (long)(s) >= 0);
2694 assert((long)(sz) - (long)(s + MINSIZE) < 0);
2698 Properties of nonrecycled chunks at the point they are malloced
2701 #if __STD_C
2702 static void do_check_malloced_chunk(mstate av, mchunkptr p, INTERNAL_SIZE_T s)
2703 #else
2704 static void do_check_malloced_chunk(av, p, s)
2705 mstate av; mchunkptr p; INTERNAL_SIZE_T s;
2706 #endif
2708 /* same as recycled case ... */
2709 do_check_remalloced_chunk(av, p, s);
2712 ... plus, must obey implementation invariant that prev_inuse is
2713 always true of any allocated chunk; i.e., that each allocated
2714 chunk borders either a previously allocated and still in-use
2715 chunk, or the base of its memory arena. This is ensured
2716 by making all allocations from the the `lowest' part of any found
2717 chunk. This does not necessarily hold however for chunks
2718 recycled via fastbins.
2721 assert(prev_inuse(p));
2726 Properties of malloc_state.
2728 This may be useful for debugging malloc, as well as detecting user
2729 programmer errors that somehow write into malloc_state.
2731 If you are extending or experimenting with this malloc, you can
2732 probably figure out how to hack this routine to print out or
2733 display chunk addresses, sizes, bins, and other instrumentation.
2736 static void do_check_malloc_state(mstate av)
2738 int i;
2739 mchunkptr p;
2740 mchunkptr q;
2741 mbinptr b;
2742 unsigned int idx;
2743 INTERNAL_SIZE_T size;
2744 unsigned long total = 0;
2745 int max_fast_bin;
2747 /* internal size_t must be no wider than pointer type */
2748 assert(sizeof(INTERNAL_SIZE_T) <= sizeof(char*));
2750 /* alignment is a power of 2 */
2751 assert((MALLOC_ALIGNMENT & (MALLOC_ALIGNMENT-1)) == 0);
2753 /* cannot run remaining checks until fully initialized */
2754 if (av->top == 0 || av->top == initial_top(av))
2755 return;
2757 /* pagesize is a power of 2 */
2758 assert((mp_.pagesize & (mp_.pagesize-1)) == 0);
2760 /* A contiguous main_arena is consistent with sbrk_base. */
2761 if (av == &main_arena && contiguous(av))
2762 assert((char*)mp_.sbrk_base + av->system_mem ==
2763 (char*)av->top + chunksize(av->top));
2765 /* properties of fastbins */
2767 /* max_fast is in allowed range */
2768 assert((get_max_fast () & ~1) <= request2size(MAX_FAST_SIZE));
2770 max_fast_bin = fastbin_index(get_max_fast ());
2772 for (i = 0; i < NFASTBINS; ++i) {
2773 p = av->fastbins[i];
2775 /* The following test can only be performed for the main arena.
2776 While mallopt calls malloc_consolidate to get rid of all fast
2777 bins (especially those larger than the new maximum) this does
2778 only happen for the main arena. Trying to do this for any
2779 other arena would mean those arenas have to be locked and
2780 malloc_consolidate be called for them. This is excessive. And
2781 even if this is acceptable to somebody it still cannot solve
2782 the problem completely since if the arena is locked a
2783 concurrent malloc call might create a new arena which then
2784 could use the newly invalid fast bins. */
2786 /* all bins past max_fast are empty */
2787 if (av == &main_arena && i > max_fast_bin)
2788 assert(p == 0);
2790 while (p != 0) {
2791 /* each chunk claims to be inuse */
2792 do_check_inuse_chunk(av, p);
2793 total += chunksize(p);
2794 /* chunk belongs in this bin */
2795 assert(fastbin_index(chunksize(p)) == i);
2796 p = p->fd;
2800 if (total != 0)
2801 assert(have_fastchunks(av));
2802 else if (!have_fastchunks(av))
2803 assert(total == 0);
2805 /* check normal bins */
2806 for (i = 1; i < NBINS; ++i) {
2807 b = bin_at(av,i);
2809 /* binmap is accurate (except for bin 1 == unsorted_chunks) */
2810 if (i >= 2) {
2811 unsigned int binbit = get_binmap(av,i);
2812 int empty = last(b) == b;
2813 if (!binbit)
2814 assert(empty);
2815 else if (!empty)
2816 assert(binbit);
2819 for (p = last(b); p != b; p = p->bk) {
2820 /* each chunk claims to be free */
2821 do_check_free_chunk(av, p);
2822 size = chunksize(p);
2823 total += size;
2824 if (i >= 2) {
2825 /* chunk belongs in bin */
2826 idx = bin_index(size);
2827 assert(idx == i);
2828 /* lists are sorted */
2829 assert(p->bk == b ||
2830 (unsigned long)chunksize(p->bk) >= (unsigned long)chunksize(p));
2832 if (!in_smallbin_range(size))
2834 if (p->fd_nextsize != NULL)
2836 if (p->fd_nextsize == p)
2837 assert (p->bk_nextsize == p);
2838 else
2840 if (p->fd_nextsize == first (b))
2841 assert (chunksize (p) < chunksize (p->fd_nextsize));
2842 else
2843 assert (chunksize (p) > chunksize (p->fd_nextsize));
2845 if (p == first (b))
2846 assert (chunksize (p) > chunksize (p->bk_nextsize));
2847 else
2848 assert (chunksize (p) < chunksize (p->bk_nextsize));
2851 else
2852 assert (p->bk_nextsize == NULL);
2854 } else if (!in_smallbin_range(size))
2855 assert (p->fd_nextsize == NULL && p->bk_nextsize == NULL);
2856 /* chunk is followed by a legal chain of inuse chunks */
2857 for (q = next_chunk(p);
2858 (q != av->top && inuse(q) &&
2859 (unsigned long)(chunksize(q)) >= MINSIZE);
2860 q = next_chunk(q))
2861 do_check_inuse_chunk(av, q);
2865 /* top chunk is OK */
2866 check_chunk(av, av->top);
2868 /* sanity checks for statistics */
2870 #ifdef NO_THREADS
2871 assert(total <= (unsigned long)(mp_.max_total_mem));
2872 assert(mp_.n_mmaps >= 0);
2873 #endif
2874 assert(mp_.n_mmaps <= mp_.max_n_mmaps);
2876 assert((unsigned long)(av->system_mem) <=
2877 (unsigned long)(av->max_system_mem));
2879 assert((unsigned long)(mp_.mmapped_mem) <=
2880 (unsigned long)(mp_.max_mmapped_mem));
2882 #ifdef NO_THREADS
2883 assert((unsigned long)(mp_.max_total_mem) >=
2884 (unsigned long)(mp_.mmapped_mem) + (unsigned long)(av->system_mem));
2885 #endif
2887 #endif
2890 /* ----------------- Support for debugging hooks -------------------- */
2891 #include "hooks.c"
2894 /* ----------- Routines dealing with system allocation -------------- */
2897 sysmalloc handles malloc cases requiring more memory from the system.
2898 On entry, it is assumed that av->top does not have enough
2899 space to service request for nb bytes, thus requiring that av->top
2900 be extended or replaced.
2903 #if __STD_C
2904 static Void_t* sYSMALLOc(INTERNAL_SIZE_T nb, mstate av)
2905 #else
2906 static Void_t* sYSMALLOc(nb, av) INTERNAL_SIZE_T nb; mstate av;
2907 #endif
2909 mchunkptr old_top; /* incoming value of av->top */
2910 INTERNAL_SIZE_T old_size; /* its size */
2911 char* old_end; /* its end address */
2913 long size; /* arg to first MORECORE or mmap call */
2914 char* brk; /* return value from MORECORE */
2916 long correction; /* arg to 2nd MORECORE call */
2917 char* snd_brk; /* 2nd return val */
2919 INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of new space */
2920 INTERNAL_SIZE_T end_misalign; /* partial page left at end of new space */
2921 char* aligned_brk; /* aligned offset into brk */
2923 mchunkptr p; /* the allocated/returned chunk */
2924 mchunkptr remainder; /* remainder from allocation */
2925 unsigned long remainder_size; /* its size */
2927 unsigned long sum; /* for updating stats */
2929 size_t pagemask = mp_.pagesize - 1;
2930 bool tried_mmap = false;
2933 #if HAVE_MMAP
2936 If have mmap, and the request size meets the mmap threshold, and
2937 the system supports mmap, and there are few enough currently
2938 allocated mmapped regions, try to directly map this request
2939 rather than expanding top.
2942 if ((unsigned long)(nb) >= (unsigned long)(mp_.mmap_threshold) &&
2943 (mp_.n_mmaps < mp_.n_mmaps_max)) {
2945 char* mm; /* return value from mmap call*/
2947 try_mmap:
2949 Round up size to nearest page. For mmapped chunks, the overhead
2950 is one SIZE_SZ unit larger than for normal chunks, because there
2951 is no following chunk whose prev_size field could be used.
2953 #if 1
2954 /* See the front_misalign handling below, for glibc there is no
2955 need for further alignments. */
2956 size = (nb + SIZE_SZ + pagemask) & ~pagemask;
2957 #else
2958 size = (nb + SIZE_SZ + MALLOC_ALIGN_MASK + pagemask) & ~pagemask;
2959 #endif
2960 tried_mmap = true;
2962 /* Don't try if size wraps around 0 */
2963 if ((unsigned long)(size) > (unsigned long)(nb)) {
2965 mm = (char*)(MMAP(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE));
2967 if (mm != MAP_FAILED) {
2970 The offset to the start of the mmapped region is stored
2971 in the prev_size field of the chunk. This allows us to adjust
2972 returned start address to meet alignment requirements here
2973 and in memalign(), and still be able to compute proper
2974 address argument for later munmap in free() and realloc().
2977 #if 1
2978 /* For glibc, chunk2mem increases the address by 2*SIZE_SZ and
2979 MALLOC_ALIGN_MASK is 2*SIZE_SZ-1. Each mmap'ed area is page
2980 aligned and therefore definitely MALLOC_ALIGN_MASK-aligned. */
2981 assert (((INTERNAL_SIZE_T)chunk2mem(mm) & MALLOC_ALIGN_MASK) == 0);
2982 #else
2983 front_misalign = (INTERNAL_SIZE_T)chunk2mem(mm) & MALLOC_ALIGN_MASK;
2984 if (front_misalign > 0) {
2985 correction = MALLOC_ALIGNMENT - front_misalign;
2986 p = (mchunkptr)(mm + correction);
2987 p->prev_size = correction;
2988 set_head(p, (size - correction) |IS_MMAPPED);
2990 else
2991 #endif
2993 p = (mchunkptr)mm;
2994 set_head(p, size|IS_MMAPPED);
2997 /* update statistics */
2999 if (++mp_.n_mmaps > mp_.max_n_mmaps)
3000 mp_.max_n_mmaps = mp_.n_mmaps;
3002 sum = mp_.mmapped_mem += size;
3003 if (sum > (unsigned long)(mp_.max_mmapped_mem))
3004 mp_.max_mmapped_mem = sum;
3005 #ifdef NO_THREADS
3006 sum += av->system_mem;
3007 if (sum > (unsigned long)(mp_.max_total_mem))
3008 mp_.max_total_mem = sum;
3009 #endif
3011 check_chunk(av, p);
3013 return chunk2mem(p);
3017 #endif
3019 /* Record incoming configuration of top */
3021 old_top = av->top;
3022 old_size = chunksize(old_top);
3023 old_end = (char*)(chunk_at_offset(old_top, old_size));
3025 brk = snd_brk = (char*)(MORECORE_FAILURE);
3028 If not the first time through, we require old_size to be
3029 at least MINSIZE and to have prev_inuse set.
3032 assert((old_top == initial_top(av) && old_size == 0) ||
3033 ((unsigned long) (old_size) >= MINSIZE &&
3034 prev_inuse(old_top) &&
3035 ((unsigned long)old_end & pagemask) == 0));
3037 /* Precondition: not enough current space to satisfy nb request */
3038 assert((unsigned long)(old_size) < (unsigned long)(nb + MINSIZE));
3040 /* Precondition: all fastbins are consolidated */
3041 assert(!have_fastchunks(av));
3044 if (av != &main_arena) {
3046 heap_info *old_heap, *heap;
3047 size_t old_heap_size;
3049 /* First try to extend the current heap. */
3050 old_heap = heap_for_ptr(old_top);
3051 old_heap_size = old_heap->size;
3052 if ((long) (MINSIZE + nb - old_size) > 0
3053 && grow_heap(old_heap, MINSIZE + nb - old_size) == 0) {
3054 av->system_mem += old_heap->size - old_heap_size;
3055 arena_mem += old_heap->size - old_heap_size;
3056 #if 0
3057 if(mmapped_mem + arena_mem + sbrked_mem > max_total_mem)
3058 max_total_mem = mmapped_mem + arena_mem + sbrked_mem;
3059 #endif
3060 set_head(old_top, (((char *)old_heap + old_heap->size) - (char *)old_top)
3061 | PREV_INUSE);
3063 else if ((heap = new_heap(nb + (MINSIZE + sizeof(*heap)), mp_.top_pad))) {
3064 /* Use a newly allocated heap. */
3065 heap->ar_ptr = av;
3066 heap->prev = old_heap;
3067 av->system_mem += heap->size;
3068 arena_mem += heap->size;
3069 #if 0
3070 if((unsigned long)(mmapped_mem + arena_mem + sbrked_mem) > max_total_mem)
3071 max_total_mem = mmapped_mem + arena_mem + sbrked_mem;
3072 #endif
3073 /* Set up the new top. */
3074 top(av) = chunk_at_offset(heap, sizeof(*heap));
3075 set_head(top(av), (heap->size - sizeof(*heap)) | PREV_INUSE);
3077 /* Setup fencepost and free the old top chunk. */
3078 /* The fencepost takes at least MINSIZE bytes, because it might
3079 become the top chunk again later. Note that a footer is set
3080 up, too, although the chunk is marked in use. */
3081 old_size -= MINSIZE;
3082 set_head(chunk_at_offset(old_top, old_size + 2*SIZE_SZ), 0|PREV_INUSE);
3083 if (old_size >= MINSIZE) {
3084 set_head(chunk_at_offset(old_top, old_size), (2*SIZE_SZ)|PREV_INUSE);
3085 set_foot(chunk_at_offset(old_top, old_size), (2*SIZE_SZ));
3086 set_head(old_top, old_size|PREV_INUSE|NON_MAIN_ARENA);
3087 _int_free(av, old_top);
3088 } else {
3089 set_head(old_top, (old_size + 2*SIZE_SZ)|PREV_INUSE);
3090 set_foot(old_top, (old_size + 2*SIZE_SZ));
3093 else if (!tried_mmap)
3094 /* We can at least try to use to mmap memory. */
3095 goto try_mmap;
3097 } else { /* av == main_arena */
3100 /* Request enough space for nb + pad + overhead */
3102 size = nb + mp_.top_pad + MINSIZE;
3105 If contiguous, we can subtract out existing space that we hope to
3106 combine with new space. We add it back later only if
3107 we don't actually get contiguous space.
3110 if (contiguous(av))
3111 size -= old_size;
3114 Round to a multiple of page size.
3115 If MORECORE is not contiguous, this ensures that we only call it
3116 with whole-page arguments. And if MORECORE is contiguous and
3117 this is not first time through, this preserves page-alignment of
3118 previous calls. Otherwise, we correct to page-align below.
3121 size = (size + pagemask) & ~pagemask;
3124 Don't try to call MORECORE if argument is so big as to appear
3125 negative. Note that since mmap takes size_t arg, it may succeed
3126 below even if we cannot call MORECORE.
3129 if (size > 0)
3130 brk = (char*)(MORECORE(size));
3132 if (brk != (char*)(MORECORE_FAILURE)) {
3133 /* Call the `morecore' hook if necessary. */
3134 if (__builtin_expect (__after_morecore_hook != NULL, 0))
3135 (*__after_morecore_hook) ();
3136 } else {
3138 If have mmap, try using it as a backup when MORECORE fails or
3139 cannot be used. This is worth doing on systems that have "holes" in
3140 address space, so sbrk cannot extend to give contiguous space, but
3141 space is available elsewhere. Note that we ignore mmap max count
3142 and threshold limits, since the space will not be used as a
3143 segregated mmap region.
3146 #if HAVE_MMAP
3147 /* Cannot merge with old top, so add its size back in */
3148 if (contiguous(av))
3149 size = (size + old_size + pagemask) & ~pagemask;
3151 /* If we are relying on mmap as backup, then use larger units */
3152 if ((unsigned long)(size) < (unsigned long)(MMAP_AS_MORECORE_SIZE))
3153 size = MMAP_AS_MORECORE_SIZE;
3155 /* Don't try if size wraps around 0 */
3156 if ((unsigned long)(size) > (unsigned long)(nb)) {
3158 char *mbrk = (char*)(MMAP(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE));
3160 if (mbrk != MAP_FAILED) {
3162 /* We do not need, and cannot use, another sbrk call to find end */
3163 brk = mbrk;
3164 snd_brk = brk + size;
3167 Record that we no longer have a contiguous sbrk region.
3168 After the first time mmap is used as backup, we do not
3169 ever rely on contiguous space since this could incorrectly
3170 bridge regions.
3172 set_noncontiguous(av);
3175 #endif
3178 if (brk != (char*)(MORECORE_FAILURE)) {
3179 if (mp_.sbrk_base == 0)
3180 mp_.sbrk_base = brk;
3181 av->system_mem += size;
3184 If MORECORE extends previous space, we can likewise extend top size.
3187 if (brk == old_end && snd_brk == (char*)(MORECORE_FAILURE))
3188 set_head(old_top, (size + old_size) | PREV_INUSE);
3190 else if (contiguous(av) && old_size && brk < old_end) {
3191 /* Oops! Someone else killed our space.. Can't touch anything. */
3192 malloc_printerr (3, "break adjusted to free malloc space", brk);
3196 Otherwise, make adjustments:
3198 * If the first time through or noncontiguous, we need to call sbrk
3199 just to find out where the end of memory lies.
3201 * We need to ensure that all returned chunks from malloc will meet
3202 MALLOC_ALIGNMENT
3204 * If there was an intervening foreign sbrk, we need to adjust sbrk
3205 request size to account for fact that we will not be able to
3206 combine new space with existing space in old_top.
3208 * Almost all systems internally allocate whole pages at a time, in
3209 which case we might as well use the whole last page of request.
3210 So we allocate enough more memory to hit a page boundary now,
3211 which in turn causes future contiguous calls to page-align.
3214 else {
3215 front_misalign = 0;
3216 end_misalign = 0;
3217 correction = 0;
3218 aligned_brk = brk;
3220 /* handle contiguous cases */
3221 if (contiguous(av)) {
3223 /* Count foreign sbrk as system_mem. */
3224 if (old_size)
3225 av->system_mem += brk - old_end;
3227 /* Guarantee alignment of first new chunk made from this space */
3229 front_misalign = (INTERNAL_SIZE_T)chunk2mem(brk) & MALLOC_ALIGN_MASK;
3230 if (front_misalign > 0) {
3233 Skip over some bytes to arrive at an aligned position.
3234 We don't need to specially mark these wasted front bytes.
3235 They will never be accessed anyway because
3236 prev_inuse of av->top (and any chunk created from its start)
3237 is always true after initialization.
3240 correction = MALLOC_ALIGNMENT - front_misalign;
3241 aligned_brk += correction;
3245 If this isn't adjacent to existing space, then we will not
3246 be able to merge with old_top space, so must add to 2nd request.
3249 correction += old_size;
3251 /* Extend the end address to hit a page boundary */
3252 end_misalign = (INTERNAL_SIZE_T)(brk + size + correction);
3253 correction += ((end_misalign + pagemask) & ~pagemask) - end_misalign;
3255 assert(correction >= 0);
3256 snd_brk = (char*)(MORECORE(correction));
3259 If can't allocate correction, try to at least find out current
3260 brk. It might be enough to proceed without failing.
3262 Note that if second sbrk did NOT fail, we assume that space
3263 is contiguous with first sbrk. This is a safe assumption unless
3264 program is multithreaded but doesn't use locks and a foreign sbrk
3265 occurred between our first and second calls.
3268 if (snd_brk == (char*)(MORECORE_FAILURE)) {
3269 correction = 0;
3270 snd_brk = (char*)(MORECORE(0));
3271 } else
3272 /* Call the `morecore' hook if necessary. */
3273 if (__builtin_expect (__after_morecore_hook != NULL, 0))
3274 (*__after_morecore_hook) ();
3277 /* handle non-contiguous cases */
3278 else {
3279 /* MORECORE/mmap must correctly align */
3280 assert(((unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK) == 0);
3282 /* Find out current end of memory */
3283 if (snd_brk == (char*)(MORECORE_FAILURE)) {
3284 snd_brk = (char*)(MORECORE(0));
3288 /* Adjust top based on results of second sbrk */
3289 if (snd_brk != (char*)(MORECORE_FAILURE)) {
3290 av->top = (mchunkptr)aligned_brk;
3291 set_head(av->top, (snd_brk - aligned_brk + correction) | PREV_INUSE);
3292 av->system_mem += correction;
3295 If not the first time through, we either have a
3296 gap due to foreign sbrk or a non-contiguous region. Insert a
3297 double fencepost at old_top to prevent consolidation with space
3298 we don't own. These fenceposts are artificial chunks that are
3299 marked as inuse and are in any case too small to use. We need
3300 two to make sizes and alignments work out.
3303 if (old_size != 0) {
3305 Shrink old_top to insert fenceposts, keeping size a
3306 multiple of MALLOC_ALIGNMENT. We know there is at least
3307 enough space in old_top to do this.
3309 old_size = (old_size - 4*SIZE_SZ) & ~MALLOC_ALIGN_MASK;
3310 set_head(old_top, old_size | PREV_INUSE);
3313 Note that the following assignments completely overwrite
3314 old_top when old_size was previously MINSIZE. This is
3315 intentional. We need the fencepost, even if old_top otherwise gets
3316 lost.
3318 chunk_at_offset(old_top, old_size )->size =
3319 (2*SIZE_SZ)|PREV_INUSE;
3321 chunk_at_offset(old_top, old_size + 2*SIZE_SZ)->size =
3322 (2*SIZE_SZ)|PREV_INUSE;
3324 /* If possible, release the rest. */
3325 if (old_size >= MINSIZE) {
3326 _int_free(av, old_top);
3333 /* Update statistics */
3334 #ifdef NO_THREADS
3335 sum = av->system_mem + mp_.mmapped_mem;
3336 if (sum > (unsigned long)(mp_.max_total_mem))
3337 mp_.max_total_mem = sum;
3338 #endif
3342 } /* if (av != &main_arena) */
3344 if ((unsigned long)av->system_mem > (unsigned long)(av->max_system_mem))
3345 av->max_system_mem = av->system_mem;
3346 check_malloc_state(av);
3348 /* finally, do the allocation */
3349 p = av->top;
3350 size = chunksize(p);
3352 /* check that one of the above allocation paths succeeded */
3353 if ((unsigned long)(size) >= (unsigned long)(nb + MINSIZE)) {
3354 remainder_size = size - nb;
3355 remainder = chunk_at_offset(p, nb);
3356 av->top = remainder;
3357 set_head(p, nb | PREV_INUSE | (av != &main_arena ? NON_MAIN_ARENA : 0));
3358 set_head(remainder, remainder_size | PREV_INUSE);
3359 check_malloced_chunk(av, p, nb);
3360 return chunk2mem(p);
3363 /* catch all failure paths */
3364 MALLOC_FAILURE_ACTION;
3365 return 0;
3370 sYSTRIm is an inverse of sorts to sYSMALLOc. It gives memory back
3371 to the system (via negative arguments to sbrk) if there is unused
3372 memory at the `high' end of the malloc pool. It is called
3373 automatically by free() when top space exceeds the trim
3374 threshold. It is also called by the public malloc_trim routine. It
3375 returns 1 if it actually released any memory, else 0.
3378 #if __STD_C
3379 static int sYSTRIm(size_t pad, mstate av)
3380 #else
3381 static int sYSTRIm(pad, av) size_t pad; mstate av;
3382 #endif
3384 long top_size; /* Amount of top-most memory */
3385 long extra; /* Amount to release */
3386 long released; /* Amount actually released */
3387 char* current_brk; /* address returned by pre-check sbrk call */
3388 char* new_brk; /* address returned by post-check sbrk call */
3389 size_t pagesz;
3391 pagesz = mp_.pagesize;
3392 top_size = chunksize(av->top);
3394 /* Release in pagesize units, keeping at least one page */
3395 extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz;
3397 if (extra > 0) {
3400 Only proceed if end of memory is where we last set it.
3401 This avoids problems if there were foreign sbrk calls.
3403 current_brk = (char*)(MORECORE(0));
3404 if (current_brk == (char*)(av->top) + top_size) {
3407 Attempt to release memory. We ignore MORECORE return value,
3408 and instead call again to find out where new end of memory is.
3409 This avoids problems if first call releases less than we asked,
3410 of if failure somehow altered brk value. (We could still
3411 encounter problems if it altered brk in some very bad way,
3412 but the only thing we can do is adjust anyway, which will cause
3413 some downstream failure.)
3416 MORECORE(-extra);
3417 /* Call the `morecore' hook if necessary. */
3418 if (__builtin_expect (__after_morecore_hook != NULL, 0))
3419 (*__after_morecore_hook) ();
3420 new_brk = (char*)(MORECORE(0));
3422 if (new_brk != (char*)MORECORE_FAILURE) {
3423 released = (long)(current_brk - new_brk);
3425 if (released != 0) {
3426 /* Success. Adjust top. */
3427 av->system_mem -= released;
3428 set_head(av->top, (top_size - released) | PREV_INUSE);
3429 check_malloc_state(av);
3430 return 1;
3435 return 0;
3438 #ifdef HAVE_MMAP
3440 static void
3441 internal_function
3442 #if __STD_C
3443 munmap_chunk(mchunkptr p)
3444 #else
3445 munmap_chunk(p) mchunkptr p;
3446 #endif
3448 INTERNAL_SIZE_T size = chunksize(p);
3450 assert (chunk_is_mmapped(p));
3451 #if 0
3452 assert(! ((char*)p >= mp_.sbrk_base && (char*)p < mp_.sbrk_base + mp_.sbrked_mem));
3453 assert((mp_.n_mmaps > 0));
3454 #endif
3456 uintptr_t block = (uintptr_t) p - p->prev_size;
3457 size_t total_size = p->prev_size + size;
3458 /* Unfortunately we have to do the compilers job by hand here. Normally
3459 we would test BLOCK and TOTAL-SIZE separately for compliance with the
3460 page size. But gcc does not recognize the optimization possibility
3461 (in the moment at least) so we combine the two values into one before
3462 the bit test. */
3463 if (__builtin_expect (((block | total_size) & (mp_.pagesize - 1)) != 0, 0))
3465 malloc_printerr (check_action, "munmap_chunk(): invalid pointer",
3466 chunk2mem (p));
3467 return;
3470 mp_.n_mmaps--;
3471 mp_.mmapped_mem -= total_size;
3473 int ret __attribute__ ((unused)) = munmap((char *)block, total_size);
3475 /* munmap returns non-zero on failure */
3476 assert(ret == 0);
3479 #if HAVE_MREMAP
3481 static mchunkptr
3482 internal_function
3483 #if __STD_C
3484 mremap_chunk(mchunkptr p, size_t new_size)
3485 #else
3486 mremap_chunk(p, new_size) mchunkptr p; size_t new_size;
3487 #endif
3489 size_t page_mask = mp_.pagesize - 1;
3490 INTERNAL_SIZE_T offset = p->prev_size;
3491 INTERNAL_SIZE_T size = chunksize(p);
3492 char *cp;
3494 assert (chunk_is_mmapped(p));
3495 #if 0
3496 assert(! ((char*)p >= mp_.sbrk_base && (char*)p < mp_.sbrk_base + mp_.sbrked_mem));
3497 assert((mp_.n_mmaps > 0));
3498 #endif
3499 assert(((size + offset) & (mp_.pagesize-1)) == 0);
3501 /* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
3502 new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask;
3504 /* No need to remap if the number of pages does not change. */
3505 if (size + offset == new_size)
3506 return p;
3508 cp = (char *)mremap((char *)p - offset, size + offset, new_size,
3509 MREMAP_MAYMOVE);
3511 if (cp == MAP_FAILED) return 0;
3513 p = (mchunkptr)(cp + offset);
3515 assert(aligned_OK(chunk2mem(p)));
3517 assert((p->prev_size == offset));
3518 set_head(p, (new_size - offset)|IS_MMAPPED);
3520 mp_.mmapped_mem -= size + offset;
3521 mp_.mmapped_mem += new_size;
3522 if ((unsigned long)mp_.mmapped_mem > (unsigned long)mp_.max_mmapped_mem)
3523 mp_.max_mmapped_mem = mp_.mmapped_mem;
3524 #ifdef NO_THREADS
3525 if ((unsigned long)(mp_.mmapped_mem + arena_mem + main_arena.system_mem) >
3526 mp_.max_total_mem)
3527 mp_.max_total_mem = mp_.mmapped_mem + arena_mem + main_arena.system_mem;
3528 #endif
3529 return p;
3532 #endif /* HAVE_MREMAP */
3534 #endif /* HAVE_MMAP */
3536 /*------------------------ Public wrappers. --------------------------------*/
3538 Void_t*
3539 public_mALLOc(size_t bytes)
3541 mstate ar_ptr;
3542 Void_t *victim;
3544 __malloc_ptr_t (*hook) (size_t, __const __malloc_ptr_t) = __malloc_hook;
3545 if (__builtin_expect (hook != NULL, 0))
3546 return (*hook)(bytes, RETURN_ADDRESS (0));
3548 arena_get(ar_ptr, bytes);
3549 if(!ar_ptr)
3550 return 0;
3551 victim = _int_malloc(ar_ptr, bytes);
3552 if(!victim) {
3553 /* Maybe the failure is due to running out of mmapped areas. */
3554 if(ar_ptr != &main_arena) {
3555 (void)mutex_unlock(&ar_ptr->mutex);
3556 ar_ptr = &main_arena;
3557 (void)mutex_lock(&ar_ptr->mutex);
3558 victim = _int_malloc(ar_ptr, bytes);
3559 (void)mutex_unlock(&ar_ptr->mutex);
3560 } else {
3561 #if USE_ARENAS
3562 /* ... or sbrk() has failed and there is still a chance to mmap() */
3563 ar_ptr = arena_get2(ar_ptr->next ? ar_ptr : 0, bytes);
3564 (void)mutex_unlock(&main_arena.mutex);
3565 if(ar_ptr) {
3566 victim = _int_malloc(ar_ptr, bytes);
3567 (void)mutex_unlock(&ar_ptr->mutex);
3569 #endif
3571 } else
3572 (void)mutex_unlock(&ar_ptr->mutex);
3573 assert(!victim || chunk_is_mmapped(mem2chunk(victim)) ||
3574 ar_ptr == arena_for_chunk(mem2chunk(victim)));
3575 return victim;
3577 #ifdef libc_hidden_def
3578 libc_hidden_def(public_mALLOc)
3579 #endif
3581 void
3582 public_fREe(Void_t* mem)
3584 mstate ar_ptr;
3585 mchunkptr p; /* chunk corresponding to mem */
3587 void (*hook) (__malloc_ptr_t, __const __malloc_ptr_t) = __free_hook;
3588 if (__builtin_expect (hook != NULL, 0)) {
3589 (*hook)(mem, RETURN_ADDRESS (0));
3590 return;
3593 if (mem == 0) /* free(0) has no effect */
3594 return;
3596 p = mem2chunk(mem);
3598 #if HAVE_MMAP
3599 if (chunk_is_mmapped(p)) /* release mmapped memory. */
3601 /* see if the dynamic brk/mmap threshold needs adjusting */
3602 if (!mp_.no_dyn_threshold
3603 && p->size > mp_.mmap_threshold
3604 && p->size <= DEFAULT_MMAP_THRESHOLD_MAX)
3606 mp_.mmap_threshold = chunksize (p);
3607 mp_.trim_threshold = 2 * mp_.mmap_threshold;
3609 munmap_chunk(p);
3610 return;
3612 #endif
3614 ar_ptr = arena_for_chunk(p);
3615 #if THREAD_STATS
3616 if(!mutex_trylock(&ar_ptr->mutex))
3617 ++(ar_ptr->stat_lock_direct);
3618 else {
3619 (void)mutex_lock(&ar_ptr->mutex);
3620 ++(ar_ptr->stat_lock_wait);
3622 #else
3623 (void)mutex_lock(&ar_ptr->mutex);
3624 #endif
3625 _int_free(ar_ptr, p);
3626 (void)mutex_unlock(&ar_ptr->mutex);
3628 #ifdef libc_hidden_def
3629 libc_hidden_def (public_fREe)
3630 #endif
3632 Void_t*
3633 public_rEALLOc(Void_t* oldmem, size_t bytes)
3635 mstate ar_ptr;
3636 INTERNAL_SIZE_T nb; /* padded request size */
3638 Void_t* newp; /* chunk to return */
3640 __malloc_ptr_t (*hook) (__malloc_ptr_t, size_t, __const __malloc_ptr_t) =
3641 __realloc_hook;
3642 if (__builtin_expect (hook != NULL, 0))
3643 return (*hook)(oldmem, bytes, RETURN_ADDRESS (0));
3645 #if REALLOC_ZERO_BYTES_FREES
3646 if (bytes == 0 && oldmem != NULL) { public_fREe(oldmem); return 0; }
3647 #endif
3649 /* realloc of null is supposed to be same as malloc */
3650 if (oldmem == 0) return public_mALLOc(bytes);
3652 /* chunk corresponding to oldmem */
3653 const mchunkptr oldp = mem2chunk(oldmem);
3654 /* its size */
3655 const INTERNAL_SIZE_T oldsize = chunksize(oldp);
3657 /* Little security check which won't hurt performance: the
3658 allocator never wrapps around at the end of the address space.
3659 Therefore we can exclude some size values which might appear
3660 here by accident or by "design" from some intruder. */
3661 if (__builtin_expect ((uintptr_t) oldp > (uintptr_t) -oldsize, 0)
3662 || __builtin_expect (misaligned_chunk (oldp), 0))
3664 malloc_printerr (check_action, "realloc(): invalid pointer", oldmem);
3665 return NULL;
3668 checked_request2size(bytes, nb);
3670 #if HAVE_MMAP
3671 if (chunk_is_mmapped(oldp))
3673 Void_t* newmem;
3675 #if HAVE_MREMAP
3676 newp = mremap_chunk(oldp, nb);
3677 if(newp) return chunk2mem(newp);
3678 #endif
3679 /* Note the extra SIZE_SZ overhead. */
3680 if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing */
3681 /* Must alloc, copy, free. */
3682 newmem = public_mALLOc(bytes);
3683 if (newmem == 0) return 0; /* propagate failure */
3684 MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ);
3685 munmap_chunk(oldp);
3686 return newmem;
3688 #endif
3690 ar_ptr = arena_for_chunk(oldp);
3691 #if THREAD_STATS
3692 if(!mutex_trylock(&ar_ptr->mutex))
3693 ++(ar_ptr->stat_lock_direct);
3694 else {
3695 (void)mutex_lock(&ar_ptr->mutex);
3696 ++(ar_ptr->stat_lock_wait);
3698 #else
3699 (void)mutex_lock(&ar_ptr->mutex);
3700 #endif
3702 #ifndef NO_THREADS
3703 /* As in malloc(), remember this arena for the next allocation. */
3704 tsd_setspecific(arena_key, (Void_t *)ar_ptr);
3705 #endif
3707 newp = _int_realloc(ar_ptr, oldp, nb);
3709 (void)mutex_unlock(&ar_ptr->mutex);
3710 assert(!newp || chunk_is_mmapped(mem2chunk(newp)) ||
3711 ar_ptr == arena_for_chunk(mem2chunk(newp)));
3713 if (newp == NULL)
3715 /* Try harder to allocate memory in other arenas. */
3716 newp = public_mALLOc(bytes);
3717 if (newp != NULL)
3719 MALLOC_COPY (newp, oldmem, oldsize - SIZE_SZ);
3720 #if THREAD_STATS
3721 if(!mutex_trylock(&ar_ptr->mutex))
3722 ++(ar_ptr->stat_lock_direct);
3723 else {
3724 (void)mutex_lock(&ar_ptr->mutex);
3725 ++(ar_ptr->stat_lock_wait);
3727 #else
3728 (void)mutex_lock(&ar_ptr->mutex);
3729 #endif
3730 _int_free(ar_ptr, oldp);
3731 (void)mutex_unlock(&ar_ptr->mutex);
3735 return newp;
3737 #ifdef libc_hidden_def
3738 libc_hidden_def (public_rEALLOc)
3739 #endif
3741 Void_t*
3742 public_mEMALIGn(size_t alignment, size_t bytes)
3744 mstate ar_ptr;
3745 Void_t *p;
3747 __malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, size_t,
3748 __const __malloc_ptr_t)) =
3749 __memalign_hook;
3750 if (__builtin_expect (hook != NULL, 0))
3751 return (*hook)(alignment, bytes, RETURN_ADDRESS (0));
3753 /* If need less alignment than we give anyway, just relay to malloc */
3754 if (alignment <= MALLOC_ALIGNMENT) return public_mALLOc(bytes);
3756 /* Otherwise, ensure that it is at least a minimum chunk size */
3757 if (alignment < MINSIZE) alignment = MINSIZE;
3759 arena_get(ar_ptr, bytes + alignment + MINSIZE);
3760 if(!ar_ptr)
3761 return 0;
3762 p = _int_memalign(ar_ptr, alignment, bytes);
3763 if(!p) {
3764 /* Maybe the failure is due to running out of mmapped areas. */
3765 if(ar_ptr != &main_arena) {
3766 (void)mutex_unlock(&ar_ptr->mutex);
3767 ar_ptr = &main_arena;
3768 (void)mutex_lock(&ar_ptr->mutex);
3769 p = _int_memalign(ar_ptr, alignment, bytes);
3770 (void)mutex_unlock(&ar_ptr->mutex);
3771 } else {
3772 #if USE_ARENAS
3773 /* ... or sbrk() has failed and there is still a chance to mmap() */
3774 mstate prev = ar_ptr->next ? ar_ptr : 0;
3775 (void)mutex_unlock(&ar_ptr->mutex);
3776 ar_ptr = arena_get2(prev, bytes);
3777 if(ar_ptr) {
3778 p = _int_memalign(ar_ptr, alignment, bytes);
3779 (void)mutex_unlock(&ar_ptr->mutex);
3781 #endif
3783 } else
3784 (void)mutex_unlock(&ar_ptr->mutex);
3785 assert(!p || chunk_is_mmapped(mem2chunk(p)) ||
3786 ar_ptr == arena_for_chunk(mem2chunk(p)));
3787 return p;
3789 #ifdef libc_hidden_def
3790 libc_hidden_def (public_mEMALIGn)
3791 #endif
3793 Void_t*
3794 public_vALLOc(size_t bytes)
3796 mstate ar_ptr;
3797 Void_t *p;
3799 if(__malloc_initialized < 0)
3800 ptmalloc_init ();
3802 size_t pagesz = mp_.pagesize;
3804 __malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, size_t,
3805 __const __malloc_ptr_t)) =
3806 __memalign_hook;
3807 if (__builtin_expect (hook != NULL, 0))
3808 return (*hook)(pagesz, bytes, RETURN_ADDRESS (0));
3810 arena_get(ar_ptr, bytes + pagesz + MINSIZE);
3811 if(!ar_ptr)
3812 return 0;
3813 p = _int_valloc(ar_ptr, bytes);
3814 (void)mutex_unlock(&ar_ptr->mutex);
3815 if(!p) {
3816 /* Maybe the failure is due to running out of mmapped areas. */
3817 if(ar_ptr != &main_arena) {
3818 (void)mutex_lock(&main_arena.mutex);
3819 p = _int_memalign(&main_arena, pagesz, bytes);
3820 (void)mutex_unlock(&main_arena.mutex);
3821 } else {
3822 #if USE_ARENAS
3823 /* ... or sbrk() has failed and there is still a chance to mmap() */
3824 ar_ptr = arena_get2(ar_ptr->next ? ar_ptr : 0, bytes);
3825 if(ar_ptr) {
3826 p = _int_memalign(ar_ptr, pagesz, bytes);
3827 (void)mutex_unlock(&ar_ptr->mutex);
3829 #endif
3832 assert(!p || chunk_is_mmapped(mem2chunk(p)) ||
3833 ar_ptr == arena_for_chunk(mem2chunk(p)));
3835 return p;
3838 Void_t*
3839 public_pVALLOc(size_t bytes)
3841 mstate ar_ptr;
3842 Void_t *p;
3844 if(__malloc_initialized < 0)
3845 ptmalloc_init ();
3847 size_t pagesz = mp_.pagesize;
3848 size_t page_mask = mp_.pagesize - 1;
3849 size_t rounded_bytes = (bytes + page_mask) & ~(page_mask);
3851 __malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, size_t,
3852 __const __malloc_ptr_t)) =
3853 __memalign_hook;
3854 if (__builtin_expect (hook != NULL, 0))
3855 return (*hook)(pagesz, rounded_bytes, RETURN_ADDRESS (0));
3857 arena_get(ar_ptr, bytes + 2*pagesz + MINSIZE);
3858 p = _int_pvalloc(ar_ptr, bytes);
3859 (void)mutex_unlock(&ar_ptr->mutex);
3860 if(!p) {
3861 /* Maybe the failure is due to running out of mmapped areas. */
3862 if(ar_ptr != &main_arena) {
3863 (void)mutex_lock(&main_arena.mutex);
3864 p = _int_memalign(&main_arena, pagesz, rounded_bytes);
3865 (void)mutex_unlock(&main_arena.mutex);
3866 } else {
3867 #if USE_ARENAS
3868 /* ... or sbrk() has failed and there is still a chance to mmap() */
3869 ar_ptr = arena_get2(ar_ptr->next ? ar_ptr : 0,
3870 bytes + 2*pagesz + MINSIZE);
3871 if(ar_ptr) {
3872 p = _int_memalign(ar_ptr, pagesz, rounded_bytes);
3873 (void)mutex_unlock(&ar_ptr->mutex);
3875 #endif
3878 assert(!p || chunk_is_mmapped(mem2chunk(p)) ||
3879 ar_ptr == arena_for_chunk(mem2chunk(p)));
3881 return p;
3884 Void_t*
3885 public_cALLOc(size_t n, size_t elem_size)
3887 mstate av;
3888 mchunkptr oldtop, p;
3889 INTERNAL_SIZE_T bytes, sz, csz, oldtopsize;
3890 Void_t* mem;
3891 unsigned long clearsize;
3892 unsigned long nclears;
3893 INTERNAL_SIZE_T* d;
3894 __malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, __const __malloc_ptr_t)) =
3895 __malloc_hook;
3897 /* size_t is unsigned so the behavior on overflow is defined. */
3898 bytes = n * elem_size;
3899 #define HALF_INTERNAL_SIZE_T \
3900 (((INTERNAL_SIZE_T) 1) << (8 * sizeof (INTERNAL_SIZE_T) / 2))
3901 if (__builtin_expect ((n | elem_size) >= HALF_INTERNAL_SIZE_T, 0)) {
3902 if (elem_size != 0 && bytes / elem_size != n) {
3903 MALLOC_FAILURE_ACTION;
3904 return 0;
3908 if (__builtin_expect (hook != NULL, 0)) {
3909 sz = bytes;
3910 mem = (*hook)(sz, RETURN_ADDRESS (0));
3911 if(mem == 0)
3912 return 0;
3913 #ifdef HAVE_MEMCPY
3914 return memset(mem, 0, sz);
3915 #else
3916 while(sz > 0) ((char*)mem)[--sz] = 0; /* rather inefficient */
3917 return mem;
3918 #endif
3921 sz = bytes;
3923 arena_get(av, sz);
3924 if(!av)
3925 return 0;
3927 /* Check if we hand out the top chunk, in which case there may be no
3928 need to clear. */
3929 #if MORECORE_CLEARS
3930 oldtop = top(av);
3931 oldtopsize = chunksize(top(av));
3932 #if MORECORE_CLEARS < 2
3933 /* Only newly allocated memory is guaranteed to be cleared. */
3934 if (av == &main_arena &&
3935 oldtopsize < mp_.sbrk_base + av->max_system_mem - (char *)oldtop)
3936 oldtopsize = (mp_.sbrk_base + av->max_system_mem - (char *)oldtop);
3937 #endif
3938 if (av != &main_arena)
3940 heap_info *heap = heap_for_ptr (oldtop);
3941 if (oldtopsize < (char *) heap + heap->mprotect_size - (char *) oldtop)
3942 oldtopsize = (char *) heap + heap->mprotect_size - (char *) oldtop;
3944 #endif
3945 mem = _int_malloc(av, sz);
3947 /* Only clearing follows, so we can unlock early. */
3948 (void)mutex_unlock(&av->mutex);
3950 assert(!mem || chunk_is_mmapped(mem2chunk(mem)) ||
3951 av == arena_for_chunk(mem2chunk(mem)));
3953 if (mem == 0) {
3954 /* Maybe the failure is due to running out of mmapped areas. */
3955 if(av != &main_arena) {
3956 (void)mutex_lock(&main_arena.mutex);
3957 mem = _int_malloc(&main_arena, sz);
3958 (void)mutex_unlock(&main_arena.mutex);
3959 } else {
3960 #if USE_ARENAS
3961 /* ... or sbrk() has failed and there is still a chance to mmap() */
3962 (void)mutex_lock(&main_arena.mutex);
3963 av = arena_get2(av->next ? av : 0, sz);
3964 (void)mutex_unlock(&main_arena.mutex);
3965 if(av) {
3966 mem = _int_malloc(av, sz);
3967 (void)mutex_unlock(&av->mutex);
3969 #endif
3971 if (mem == 0) return 0;
3973 p = mem2chunk(mem);
3975 /* Two optional cases in which clearing not necessary */
3976 #if HAVE_MMAP
3977 if (chunk_is_mmapped (p))
3979 if (__builtin_expect (perturb_byte, 0))
3980 MALLOC_ZERO (mem, sz);
3981 return mem;
3983 #endif
3985 csz = chunksize(p);
3987 #if MORECORE_CLEARS
3988 if (perturb_byte == 0 && (p == oldtop && csz > oldtopsize)) {
3989 /* clear only the bytes from non-freshly-sbrked memory */
3990 csz = oldtopsize;
3992 #endif
3994 /* Unroll clear of <= 36 bytes (72 if 8byte sizes). We know that
3995 contents have an odd number of INTERNAL_SIZE_T-sized words;
3996 minimally 3. */
3997 d = (INTERNAL_SIZE_T*)mem;
3998 clearsize = csz - SIZE_SZ;
3999 nclears = clearsize / sizeof(INTERNAL_SIZE_T);
4000 assert(nclears >= 3);
4002 if (nclears > 9)
4003 MALLOC_ZERO(d, clearsize);
4005 else {
4006 *(d+0) = 0;
4007 *(d+1) = 0;
4008 *(d+2) = 0;
4009 if (nclears > 4) {
4010 *(d+3) = 0;
4011 *(d+4) = 0;
4012 if (nclears > 6) {
4013 *(d+5) = 0;
4014 *(d+6) = 0;
4015 if (nclears > 8) {
4016 *(d+7) = 0;
4017 *(d+8) = 0;
4023 return mem;
4026 #ifndef _LIBC
4028 Void_t**
4029 public_iCALLOc(size_t n, size_t elem_size, Void_t** chunks)
4031 mstate ar_ptr;
4032 Void_t** m;
4034 arena_get(ar_ptr, n*elem_size);
4035 if(!ar_ptr)
4036 return 0;
4038 m = _int_icalloc(ar_ptr, n, elem_size, chunks);
4039 (void)mutex_unlock(&ar_ptr->mutex);
4040 return m;
4043 Void_t**
4044 public_iCOMALLOc(size_t n, size_t sizes[], Void_t** chunks)
4046 mstate ar_ptr;
4047 Void_t** m;
4049 arena_get(ar_ptr, 0);
4050 if(!ar_ptr)
4051 return 0;
4053 m = _int_icomalloc(ar_ptr, n, sizes, chunks);
4054 (void)mutex_unlock(&ar_ptr->mutex);
4055 return m;
4058 void
4059 public_cFREe(Void_t* m)
4061 public_fREe(m);
4064 #endif /* _LIBC */
4067 public_mTRIm(size_t s)
4069 int result = 0;
4071 if(__malloc_initialized < 0)
4072 ptmalloc_init ();
4074 mstate ar_ptr = &main_arena;
4077 (void) mutex_lock (&ar_ptr->mutex);
4078 result |= mTRIm (ar_ptr, s);
4079 (void) mutex_unlock (&ar_ptr->mutex);
4081 ar_ptr = ar_ptr->next;
4083 while (ar_ptr != &main_arena);
4085 return result;
4088 size_t
4089 public_mUSABLe(Void_t* m)
4091 size_t result;
4093 result = mUSABLe(m);
4094 return result;
4097 void
4098 public_mSTATs()
4100 mSTATs();
4103 struct mallinfo public_mALLINFo()
4105 struct mallinfo m;
4107 if(__malloc_initialized < 0)
4108 ptmalloc_init ();
4109 (void)mutex_lock(&main_arena.mutex);
4110 m = mALLINFo(&main_arena);
4111 (void)mutex_unlock(&main_arena.mutex);
4112 return m;
4116 public_mALLOPt(int p, int v)
4118 int result;
4119 result = mALLOPt(p, v);
4120 return result;
4124 ------------------------------ malloc ------------------------------
4127 static Void_t*
4128 _int_malloc(mstate av, size_t bytes)
4130 INTERNAL_SIZE_T nb; /* normalized request size */
4131 unsigned int idx; /* associated bin index */
4132 mbinptr bin; /* associated bin */
4133 mfastbinptr* fb; /* associated fastbin */
4135 mchunkptr victim; /* inspected/selected chunk */
4136 INTERNAL_SIZE_T size; /* its size */
4137 int victim_index; /* its bin index */
4139 mchunkptr remainder; /* remainder from a split */
4140 unsigned long remainder_size; /* its size */
4142 unsigned int block; /* bit map traverser */
4143 unsigned int bit; /* bit map traverser */
4144 unsigned int map; /* current word of binmap */
4146 mchunkptr fwd; /* misc temp for linking */
4147 mchunkptr bck; /* misc temp for linking */
4150 Convert request size to internal form by adding SIZE_SZ bytes
4151 overhead plus possibly more to obtain necessary alignment and/or
4152 to obtain a size of at least MINSIZE, the smallest allocatable
4153 size. Also, checked_request2size traps (returning 0) request sizes
4154 that are so large that they wrap around zero when padded and
4155 aligned.
4158 checked_request2size(bytes, nb);
4161 If the size qualifies as a fastbin, first check corresponding bin.
4162 This code is safe to execute even if av is not yet initialized, so we
4163 can try it without checking, which saves some time on this fast path.
4166 if ((unsigned long)(nb) <= (unsigned long)(get_max_fast ())) {
4167 long int idx = fastbin_index(nb);
4168 fb = &(av->fastbins[idx]);
4169 if ( (victim = *fb) != 0) {
4170 if (__builtin_expect (fastbin_index (chunksize (victim)) != idx, 0))
4171 malloc_printerr (check_action, "malloc(): memory corruption (fast)",
4172 chunk2mem (victim));
4173 *fb = victim->fd;
4174 check_remalloced_chunk(av, victim, nb);
4175 void *p = chunk2mem(victim);
4176 if (__builtin_expect (perturb_byte, 0))
4177 alloc_perturb (p, bytes);
4178 return p;
4183 If a small request, check regular bin. Since these "smallbins"
4184 hold one size each, no searching within bins is necessary.
4185 (For a large request, we need to wait until unsorted chunks are
4186 processed to find best fit. But for small ones, fits are exact
4187 anyway, so we can check now, which is faster.)
4190 if (in_smallbin_range(nb)) {
4191 idx = smallbin_index(nb);
4192 bin = bin_at(av,idx);
4194 if ( (victim = last(bin)) != bin) {
4195 if (victim == 0) /* initialization check */
4196 malloc_consolidate(av);
4197 else {
4198 bck = victim->bk;
4199 set_inuse_bit_at_offset(victim, nb);
4200 bin->bk = bck;
4201 bck->fd = bin;
4203 if (av != &main_arena)
4204 victim->size |= NON_MAIN_ARENA;
4205 check_malloced_chunk(av, victim, nb);
4206 void *p = chunk2mem(victim);
4207 if (__builtin_expect (perturb_byte, 0))
4208 alloc_perturb (p, bytes);
4209 return p;
4215 If this is a large request, consolidate fastbins before continuing.
4216 While it might look excessive to kill all fastbins before
4217 even seeing if there is space available, this avoids
4218 fragmentation problems normally associated with fastbins.
4219 Also, in practice, programs tend to have runs of either small or
4220 large requests, but less often mixtures, so consolidation is not
4221 invoked all that often in most programs. And the programs that
4222 it is called frequently in otherwise tend to fragment.
4225 else {
4226 idx = largebin_index(nb);
4227 if (have_fastchunks(av))
4228 malloc_consolidate(av);
4232 Process recently freed or remaindered chunks, taking one only if
4233 it is exact fit, or, if this a small request, the chunk is remainder from
4234 the most recent non-exact fit. Place other traversed chunks in
4235 bins. Note that this step is the only place in any routine where
4236 chunks are placed in bins.
4238 The outer loop here is needed because we might not realize until
4239 near the end of malloc that we should have consolidated, so must
4240 do so and retry. This happens at most once, and only when we would
4241 otherwise need to expand memory to service a "small" request.
4244 for(;;) {
4246 int iters = 0;
4247 while ( (victim = unsorted_chunks(av)->bk) != unsorted_chunks(av)) {
4248 bck = victim->bk;
4249 if (__builtin_expect (victim->size <= 2 * SIZE_SZ, 0)
4250 || __builtin_expect (victim->size > av->system_mem, 0))
4251 malloc_printerr (check_action, "malloc(): memory corruption",
4252 chunk2mem (victim));
4253 size = chunksize(victim);
4256 If a small request, try to use last remainder if it is the
4257 only chunk in unsorted bin. This helps promote locality for
4258 runs of consecutive small requests. This is the only
4259 exception to best-fit, and applies only when there is
4260 no exact fit for a small chunk.
4263 if (in_smallbin_range(nb) &&
4264 bck == unsorted_chunks(av) &&
4265 victim == av->last_remainder &&
4266 (unsigned long)(size) > (unsigned long)(nb + MINSIZE)) {
4268 /* split and reattach remainder */
4269 remainder_size = size - nb;
4270 remainder = chunk_at_offset(victim, nb);
4271 unsorted_chunks(av)->bk = unsorted_chunks(av)->fd = remainder;
4272 av->last_remainder = remainder;
4273 remainder->bk = remainder->fd = unsorted_chunks(av);
4274 if (!in_smallbin_range(remainder_size))
4276 remainder->fd_nextsize = NULL;
4277 remainder->bk_nextsize = NULL;
4280 set_head(victim, nb | PREV_INUSE |
4281 (av != &main_arena ? NON_MAIN_ARENA : 0));
4282 set_head(remainder, remainder_size | PREV_INUSE);
4283 set_foot(remainder, remainder_size);
4285 check_malloced_chunk(av, victim, nb);
4286 void *p = chunk2mem(victim);
4287 if (__builtin_expect (perturb_byte, 0))
4288 alloc_perturb (p, bytes);
4289 return p;
4292 /* remove from unsorted list */
4293 unsorted_chunks(av)->bk = bck;
4294 bck->fd = unsorted_chunks(av);
4296 /* Take now instead of binning if exact fit */
4298 if (size == nb) {
4299 set_inuse_bit_at_offset(victim, size);
4300 if (av != &main_arena)
4301 victim->size |= NON_MAIN_ARENA;
4302 check_malloced_chunk(av, victim, nb);
4303 void *p = chunk2mem(victim);
4304 if (__builtin_expect (perturb_byte, 0))
4305 alloc_perturb (p, bytes);
4306 return p;
4309 /* place chunk in bin */
4311 if (in_smallbin_range(size)) {
4312 victim_index = smallbin_index(size);
4313 bck = bin_at(av, victim_index);
4314 fwd = bck->fd;
4316 else {
4317 victim_index = largebin_index(size);
4318 bck = bin_at(av, victim_index);
4319 fwd = bck->fd;
4321 /* maintain large bins in sorted order */
4322 if (fwd != bck) {
4323 /* Or with inuse bit to speed comparisons */
4324 size |= PREV_INUSE;
4325 /* if smaller than smallest, bypass loop below */
4326 assert((bck->bk->size & NON_MAIN_ARENA) == 0);
4327 if ((unsigned long)(size) < (unsigned long)(bck->bk->size)) {
4328 fwd = bck;
4329 bck = bck->bk;
4331 victim->fd_nextsize = fwd->fd;
4332 victim->bk_nextsize = fwd->fd->bk_nextsize;
4333 fwd->fd->bk_nextsize = victim->bk_nextsize->fd_nextsize = victim;
4335 else {
4336 assert((fwd->size & NON_MAIN_ARENA) == 0);
4337 while ((unsigned long) size < fwd->size)
4339 fwd = fwd->fd_nextsize;
4340 assert((fwd->size & NON_MAIN_ARENA) == 0);
4343 if ((unsigned long) size == (unsigned long) fwd->size)
4344 /* Always insert in the second position. */
4345 fwd = fwd->fd;
4346 else
4348 victim->fd_nextsize = fwd;
4349 victim->bk_nextsize = fwd->bk_nextsize;
4350 fwd->bk_nextsize = victim;
4351 victim->bk_nextsize->fd_nextsize = victim;
4353 bck = fwd->bk;
4355 } else
4356 victim->fd_nextsize = victim->bk_nextsize = victim;
4359 mark_bin(av, victim_index);
4360 victim->bk = bck;
4361 victim->fd = fwd;
4362 fwd->bk = victim;
4363 bck->fd = victim;
4365 #define MAX_ITERS 10000
4366 if (++iters >= MAX_ITERS)
4367 break;
4371 If a large request, scan through the chunks of current bin in
4372 sorted order to find smallest that fits. Use the skip list for this.
4375 if (!in_smallbin_range(nb)) {
4376 bin = bin_at(av, idx);
4378 /* skip scan if empty or largest chunk is too small */
4379 if ((victim = first(bin)) != bin &&
4380 (unsigned long)(victim->size) >= (unsigned long)(nb)) {
4382 victim = victim->bk_nextsize;
4383 while (((unsigned long)(size = chunksize(victim)) <
4384 (unsigned long)(nb)))
4385 victim = victim->bk_nextsize;
4387 /* Avoid removing the first entry for a size so that the skip
4388 list does not have to be rerouted. */
4389 if (victim != last(bin) && victim->size == victim->fd->size)
4390 victim = victim->fd;
4392 remainder_size = size - nb;
4393 unlink(victim, bck, fwd);
4395 /* Exhaust */
4396 if (remainder_size < MINSIZE) {
4397 set_inuse_bit_at_offset(victim, size);
4398 if (av != &main_arena)
4399 victim->size |= NON_MAIN_ARENA;
4401 /* Split */
4402 else {
4403 remainder = chunk_at_offset(victim, nb);
4404 /* We cannot assume the unsorted list is empty and therefore
4405 have to perform a complete insert here. */
4406 bck = unsorted_chunks(av);
4407 fwd = bck->fd;
4408 remainder->bk = bck;
4409 remainder->fd = fwd;
4410 bck->fd = remainder;
4411 fwd->bk = remainder;
4412 if (!in_smallbin_range(remainder_size))
4414 remainder->fd_nextsize = NULL;
4415 remainder->bk_nextsize = NULL;
4417 set_head(victim, nb | PREV_INUSE |
4418 (av != &main_arena ? NON_MAIN_ARENA : 0));
4419 set_head(remainder, remainder_size | PREV_INUSE);
4420 set_foot(remainder, remainder_size);
4422 check_malloced_chunk(av, victim, nb);
4423 void *p = chunk2mem(victim);
4424 if (__builtin_expect (perturb_byte, 0))
4425 alloc_perturb (p, bytes);
4426 return p;
4431 Search for a chunk by scanning bins, starting with next largest
4432 bin. This search is strictly by best-fit; i.e., the smallest
4433 (with ties going to approximately the least recently used) chunk
4434 that fits is selected.
4436 The bitmap avoids needing to check that most blocks are nonempty.
4437 The particular case of skipping all bins during warm-up phases
4438 when no chunks have been returned yet is faster than it might look.
4441 ++idx;
4442 bin = bin_at(av,idx);
4443 block = idx2block(idx);
4444 map = av->binmap[block];
4445 bit = idx2bit(idx);
4447 for (;;) {
4449 /* Skip rest of block if there are no more set bits in this block. */
4450 if (bit > map || bit == 0) {
4451 do {
4452 if (++block >= BINMAPSIZE) /* out of bins */
4453 goto use_top;
4454 } while ( (map = av->binmap[block]) == 0);
4456 bin = bin_at(av, (block << BINMAPSHIFT));
4457 bit = 1;
4460 /* Advance to bin with set bit. There must be one. */
4461 while ((bit & map) == 0) {
4462 bin = next_bin(bin);
4463 bit <<= 1;
4464 assert(bit != 0);
4467 /* Inspect the bin. It is likely to be non-empty */
4468 victim = last(bin);
4470 /* If a false alarm (empty bin), clear the bit. */
4471 if (victim == bin) {
4472 av->binmap[block] = map &= ~bit; /* Write through */
4473 bin = next_bin(bin);
4474 bit <<= 1;
4477 else {
4478 size = chunksize(victim);
4480 /* We know the first chunk in this bin is big enough to use. */
4481 assert((unsigned long)(size) >= (unsigned long)(nb));
4483 remainder_size = size - nb;
4485 /* unlink */
4486 unlink(victim, bck, fwd);
4488 /* Exhaust */
4489 if (remainder_size < MINSIZE) {
4490 set_inuse_bit_at_offset(victim, size);
4491 if (av != &main_arena)
4492 victim->size |= NON_MAIN_ARENA;
4495 /* Split */
4496 else {
4497 remainder = chunk_at_offset(victim, nb);
4499 /* We cannot assume the unsorted list is empty and therefore
4500 have to perform a complete insert here. */
4501 bck = unsorted_chunks(av);
4502 fwd = bck->fd;
4503 remainder->bk = bck;
4504 remainder->fd = fwd;
4505 bck->fd = remainder;
4506 fwd->bk = remainder;
4508 /* advertise as last remainder */
4509 if (in_smallbin_range(nb))
4510 av->last_remainder = remainder;
4511 if (!in_smallbin_range(remainder_size))
4513 remainder->fd_nextsize = NULL;
4514 remainder->bk_nextsize = NULL;
4516 set_head(victim, nb | PREV_INUSE |
4517 (av != &main_arena ? NON_MAIN_ARENA : 0));
4518 set_head(remainder, remainder_size | PREV_INUSE);
4519 set_foot(remainder, remainder_size);
4521 check_malloced_chunk(av, victim, nb);
4522 void *p = chunk2mem(victim);
4523 if (__builtin_expect (perturb_byte, 0))
4524 alloc_perturb (p, bytes);
4525 return p;
4529 use_top:
4531 If large enough, split off the chunk bordering the end of memory
4532 (held in av->top). Note that this is in accord with the best-fit
4533 search rule. In effect, av->top is treated as larger (and thus
4534 less well fitting) than any other available chunk since it can
4535 be extended to be as large as necessary (up to system
4536 limitations).
4538 We require that av->top always exists (i.e., has size >=
4539 MINSIZE) after initialization, so if it would otherwise be
4540 exhausted by current request, it is replenished. (The main
4541 reason for ensuring it exists is that we may need MINSIZE space
4542 to put in fenceposts in sysmalloc.)
4545 victim = av->top;
4546 size = chunksize(victim);
4548 if ((unsigned long)(size) >= (unsigned long)(nb + MINSIZE)) {
4549 remainder_size = size - nb;
4550 remainder = chunk_at_offset(victim, nb);
4551 av->top = remainder;
4552 set_head(victim, nb | PREV_INUSE |
4553 (av != &main_arena ? NON_MAIN_ARENA : 0));
4554 set_head(remainder, remainder_size | PREV_INUSE);
4556 check_malloced_chunk(av, victim, nb);
4557 void *p = chunk2mem(victim);
4558 if (__builtin_expect (perturb_byte, 0))
4559 alloc_perturb (p, bytes);
4560 return p;
4564 If there is space available in fastbins, consolidate and retry,
4565 to possibly avoid expanding memory. This can occur only if nb is
4566 in smallbin range so we didn't consolidate upon entry.
4569 else if (have_fastchunks(av)) {
4570 assert(in_smallbin_range(nb));
4571 malloc_consolidate(av);
4572 idx = smallbin_index(nb); /* restore original bin index */
4576 Otherwise, relay to handle system-dependent cases
4578 else {
4579 void *p = sYSMALLOc(nb, av);
4580 if (p != NULL && __builtin_expect (perturb_byte, 0))
4581 alloc_perturb (p, bytes);
4582 return p;
4588 ------------------------------ free ------------------------------
4591 static void
4592 _int_free(mstate av, mchunkptr p)
4594 INTERNAL_SIZE_T size; /* its size */
4595 mfastbinptr* fb; /* associated fastbin */
4596 mchunkptr nextchunk; /* next contiguous chunk */
4597 INTERNAL_SIZE_T nextsize; /* its size */
4598 int nextinuse; /* true if nextchunk is used */
4599 INTERNAL_SIZE_T prevsize; /* size of previous contiguous chunk */
4600 mchunkptr bck; /* misc temp for linking */
4601 mchunkptr fwd; /* misc temp for linking */
4603 const char *errstr = NULL;
4605 size = chunksize(p);
4607 /* Little security check which won't hurt performance: the
4608 allocator never wrapps around at the end of the address space.
4609 Therefore we can exclude some size values which might appear
4610 here by accident or by "design" from some intruder. */
4611 if (__builtin_expect ((uintptr_t) p > (uintptr_t) -size, 0)
4612 || __builtin_expect (misaligned_chunk (p), 0))
4614 errstr = "free(): invalid pointer";
4615 errout:
4616 malloc_printerr (check_action, errstr, chunk2mem(p));
4617 return;
4619 /* We know that each chunk is at least MINSIZE bytes in size. */
4620 if (__builtin_expect (size < MINSIZE, 0))
4622 errstr = "free(): invalid size";
4623 goto errout;
4626 check_inuse_chunk(av, p);
4629 If eligible, place chunk on a fastbin so it can be found
4630 and used quickly in malloc.
4633 if ((unsigned long)(size) <= (unsigned long)(get_max_fast ())
4635 #if TRIM_FASTBINS
4637 If TRIM_FASTBINS set, don't place chunks
4638 bordering top into fastbins
4640 && (chunk_at_offset(p, size) != av->top)
4641 #endif
4644 if (__builtin_expect (chunk_at_offset (p, size)->size <= 2 * SIZE_SZ, 0)
4645 || __builtin_expect (chunksize (chunk_at_offset (p, size))
4646 >= av->system_mem, 0))
4648 errstr = "free(): invalid next size (fast)";
4649 goto errout;
4652 set_fastchunks(av);
4653 fb = &(av->fastbins[fastbin_index(size)]);
4654 /* Another simple check: make sure the top of the bin is not the
4655 record we are going to add (i.e., double free). */
4656 if (__builtin_expect (*fb == p, 0))
4658 errstr = "double free or corruption (fasttop)";
4659 goto errout;
4662 if (__builtin_expect (perturb_byte, 0))
4663 free_perturb (chunk2mem(p), size - SIZE_SZ);
4665 p->fd = *fb;
4666 *fb = p;
4670 Consolidate other non-mmapped chunks as they arrive.
4673 else if (!chunk_is_mmapped(p)) {
4674 nextchunk = chunk_at_offset(p, size);
4676 /* Lightweight tests: check whether the block is already the
4677 top block. */
4678 if (__builtin_expect (p == av->top, 0))
4680 errstr = "double free or corruption (top)";
4681 goto errout;
4683 /* Or whether the next chunk is beyond the boundaries of the arena. */
4684 if (__builtin_expect (contiguous (av)
4685 && (char *) nextchunk
4686 >= ((char *) av->top + chunksize(av->top)), 0))
4688 errstr = "double free or corruption (out)";
4689 goto errout;
4691 /* Or whether the block is actually not marked used. */
4692 if (__builtin_expect (!prev_inuse(nextchunk), 0))
4694 errstr = "double free or corruption (!prev)";
4695 goto errout;
4698 nextsize = chunksize(nextchunk);
4699 if (__builtin_expect (nextchunk->size <= 2 * SIZE_SZ, 0)
4700 || __builtin_expect (nextsize >= av->system_mem, 0))
4702 errstr = "free(): invalid next size (normal)";
4703 goto errout;
4706 if (__builtin_expect (perturb_byte, 0))
4707 free_perturb (chunk2mem(p), size - SIZE_SZ);
4709 /* consolidate backward */
4710 if (!prev_inuse(p)) {
4711 prevsize = p->prev_size;
4712 size += prevsize;
4713 p = chunk_at_offset(p, -((long) prevsize));
4714 unlink(p, bck, fwd);
4717 if (nextchunk != av->top) {
4718 /* get and clear inuse bit */
4719 nextinuse = inuse_bit_at_offset(nextchunk, nextsize);
4721 /* consolidate forward */
4722 if (!nextinuse) {
4723 unlink(nextchunk, bck, fwd);
4724 size += nextsize;
4725 } else
4726 clear_inuse_bit_at_offset(nextchunk, 0);
4729 Place the chunk in unsorted chunk list. Chunks are
4730 not placed into regular bins until after they have
4731 been given one chance to be used in malloc.
4734 bck = unsorted_chunks(av);
4735 fwd = bck->fd;
4736 p->fd = fwd;
4737 p->bk = bck;
4738 if (!in_smallbin_range(size))
4740 p->fd_nextsize = NULL;
4741 p->bk_nextsize = NULL;
4743 bck->fd = p;
4744 fwd->bk = p;
4746 set_head(p, size | PREV_INUSE);
4747 set_foot(p, size);
4749 check_free_chunk(av, p);
4753 If the chunk borders the current high end of memory,
4754 consolidate into top
4757 else {
4758 size += nextsize;
4759 set_head(p, size | PREV_INUSE);
4760 av->top = p;
4761 check_chunk(av, p);
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.
4769 Unless max_fast is 0, we don't know if there are fastbins
4770 bordering top, so we cannot tell for sure whether threshold
4771 has been reached unless fastbins are consolidated. But we
4772 don't want to consolidate on each free. As a compromise,
4773 consolidation is performed if FASTBIN_CONSOLIDATION_THRESHOLD
4774 is reached.
4777 if ((unsigned long)(size) >= FASTBIN_CONSOLIDATION_THRESHOLD) {
4778 if (have_fastchunks(av))
4779 malloc_consolidate(av);
4781 if (av == &main_arena) {
4782 #ifndef MORECORE_CANNOT_TRIM
4783 if ((unsigned long)(chunksize(av->top)) >=
4784 (unsigned long)(mp_.trim_threshold))
4785 sYSTRIm(mp_.top_pad, av);
4786 #endif
4787 } else {
4788 /* Always try heap_trim(), even if the top chunk is not
4789 large, because the corresponding heap might go away. */
4790 heap_info *heap = heap_for_ptr(top(av));
4792 assert(heap->ar_ptr == av);
4793 heap_trim(heap, mp_.top_pad);
4799 If the chunk was allocated via mmap, release via munmap(). Note
4800 that if HAVE_MMAP is false but chunk_is_mmapped is true, then
4801 user must have overwritten memory. There's nothing we can do to
4802 catch this error unless MALLOC_DEBUG is set, in which case
4803 check_inuse_chunk (above) will have triggered error.
4806 else {
4807 #if HAVE_MMAP
4808 munmap_chunk (p);
4809 #endif
4814 ------------------------- malloc_consolidate -------------------------
4816 malloc_consolidate is a specialized version of free() that tears
4817 down chunks held in fastbins. Free itself cannot be used for this
4818 purpose since, among other things, it might place chunks back onto
4819 fastbins. So, instead, we need to use a minor variant of the same
4820 code.
4822 Also, because this routine needs to be called the first time through
4823 malloc anyway, it turns out to be the perfect place to trigger
4824 initialization code.
4827 #if __STD_C
4828 static void malloc_consolidate(mstate av)
4829 #else
4830 static void malloc_consolidate(av) mstate av;
4831 #endif
4833 mfastbinptr* fb; /* current fastbin being consolidated */
4834 mfastbinptr* maxfb; /* last fastbin (for loop control) */
4835 mchunkptr p; /* current chunk being consolidated */
4836 mchunkptr nextp; /* next chunk to consolidate */
4837 mchunkptr unsorted_bin; /* bin header */
4838 mchunkptr first_unsorted; /* chunk to link to */
4840 /* These have same use as in free() */
4841 mchunkptr nextchunk;
4842 INTERNAL_SIZE_T size;
4843 INTERNAL_SIZE_T nextsize;
4844 INTERNAL_SIZE_T prevsize;
4845 int nextinuse;
4846 mchunkptr bck;
4847 mchunkptr fwd;
4850 If max_fast is 0, we know that av hasn't
4851 yet been initialized, in which case do so below
4854 if (get_max_fast () != 0) {
4855 clear_fastchunks(av);
4857 unsorted_bin = unsorted_chunks(av);
4860 Remove each chunk from fast bin and consolidate it, placing it
4861 then in unsorted bin. Among other reasons for doing this,
4862 placing in unsorted bin avoids needing to calculate actual bins
4863 until malloc is sure that chunks aren't immediately going to be
4864 reused anyway.
4867 #if 0
4868 /* It is wrong to limit the fast bins to search using get_max_fast
4869 because, except for the main arena, all the others might have
4870 blocks in the high fast bins. It's not worth it anyway, just
4871 search all bins all the time. */
4872 maxfb = &(av->fastbins[fastbin_index(get_max_fast ())]);
4873 #else
4874 maxfb = &(av->fastbins[NFASTBINS - 1]);
4875 #endif
4876 fb = &(av->fastbins[0]);
4877 do {
4878 if ( (p = *fb) != 0) {
4879 *fb = 0;
4881 do {
4882 check_inuse_chunk(av, p);
4883 nextp = p->fd;
4885 /* Slightly streamlined version of consolidation code in free() */
4886 size = p->size & ~(PREV_INUSE|NON_MAIN_ARENA);
4887 nextchunk = chunk_at_offset(p, size);
4888 nextsize = chunksize(nextchunk);
4890 if (!prev_inuse(p)) {
4891 prevsize = p->prev_size;
4892 size += prevsize;
4893 p = chunk_at_offset(p, -((long) prevsize));
4894 unlink(p, bck, fwd);
4897 if (nextchunk != av->top) {
4898 nextinuse = inuse_bit_at_offset(nextchunk, nextsize);
4900 if (!nextinuse) {
4901 size += nextsize;
4902 unlink(nextchunk, bck, fwd);
4903 } else
4904 clear_inuse_bit_at_offset(nextchunk, 0);
4906 first_unsorted = unsorted_bin->fd;
4907 unsorted_bin->fd = p;
4908 first_unsorted->bk = p;
4910 if (!in_smallbin_range (size)) {
4911 p->fd_nextsize = NULL;
4912 p->bk_nextsize = NULL;
4915 set_head(p, size | PREV_INUSE);
4916 p->bk = unsorted_bin;
4917 p->fd = first_unsorted;
4918 set_foot(p, size);
4921 else {
4922 size += nextsize;
4923 set_head(p, size | PREV_INUSE);
4924 av->top = p;
4927 } while ( (p = nextp) != 0);
4930 } while (fb++ != maxfb);
4932 else {
4933 malloc_init_state(av);
4934 check_malloc_state(av);
4939 ------------------------------ realloc ------------------------------
4942 Void_t*
4943 _int_realloc(mstate av, mchunkptr oldp, INTERNAL_SIZE_T nb)
4945 mchunkptr newp; /* chunk to return */
4946 INTERNAL_SIZE_T newsize; /* its size */
4947 Void_t* newmem; /* corresponding user mem */
4949 mchunkptr next; /* next contiguous chunk after oldp */
4951 mchunkptr remainder; /* extra space at end of newp */
4952 unsigned long remainder_size; /* its size */
4954 mchunkptr bck; /* misc temp for linking */
4955 mchunkptr fwd; /* misc temp for linking */
4957 unsigned long copysize; /* bytes to copy */
4958 unsigned int ncopies; /* INTERNAL_SIZE_T words to copy */
4959 INTERNAL_SIZE_T* s; /* copy source */
4960 INTERNAL_SIZE_T* d; /* copy destination */
4962 const char *errstr = NULL;
4964 /* Simple tests for old block integrity. */
4965 if (__builtin_expect (misaligned_chunk (oldp), 0))
4967 errstr = "realloc(): invalid pointer";
4968 errout:
4969 malloc_printerr (check_action, errstr, chunk2mem(oldp));
4970 return NULL;
4973 /* oldmem size */
4974 const INTERNAL_SIZE_T oldsize = chunksize(oldp);
4976 if (__builtin_expect (oldp->size <= 2 * SIZE_SZ, 0)
4977 || __builtin_expect (oldsize >= av->system_mem, 0))
4979 errstr = "realloc(): invalid old size";
4980 goto errout;
4983 check_inuse_chunk(av, oldp);
4985 if (!chunk_is_mmapped(oldp)) {
4987 next = chunk_at_offset(oldp, oldsize);
4988 INTERNAL_SIZE_T nextsize = chunksize(next);
4989 if (__builtin_expect (next->size <= 2 * SIZE_SZ, 0)
4990 || __builtin_expect (nextsize >= av->system_mem, 0))
4992 errstr = "realloc(): invalid next size";
4993 goto errout;
4996 if ((unsigned long)(oldsize) >= (unsigned long)(nb)) {
4997 /* already big enough; split below */
4998 newp = oldp;
4999 newsize = oldsize;
5002 else {
5003 /* Try to expand forward into top */
5004 if (next == av->top &&
5005 (unsigned long)(newsize = oldsize + nextsize) >=
5006 (unsigned long)(nb + MINSIZE)) {
5007 set_head_size(oldp, nb | (av != &main_arena ? NON_MAIN_ARENA : 0));
5008 av->top = chunk_at_offset(oldp, nb);
5009 set_head(av->top, (newsize - nb) | PREV_INUSE);
5010 check_inuse_chunk(av, oldp);
5011 return chunk2mem(oldp);
5014 /* Try to expand forward into next chunk; split off remainder below */
5015 else if (next != av->top &&
5016 !inuse(next) &&
5017 (unsigned long)(newsize = oldsize + nextsize) >=
5018 (unsigned long)(nb)) {
5019 newp = oldp;
5020 unlink(next, bck, fwd);
5023 /* allocate, copy, free */
5024 else {
5025 newmem = _int_malloc(av, nb - MALLOC_ALIGN_MASK);
5026 if (newmem == 0)
5027 return 0; /* propagate failure */
5029 newp = mem2chunk(newmem);
5030 newsize = chunksize(newp);
5033 Avoid copy if newp is next chunk after oldp.
5035 if (newp == next) {
5036 newsize += oldsize;
5037 newp = oldp;
5039 else {
5041 Unroll copy of <= 36 bytes (72 if 8byte sizes)
5042 We know that contents have an odd number of
5043 INTERNAL_SIZE_T-sized words; minimally 3.
5046 copysize = oldsize - SIZE_SZ;
5047 s = (INTERNAL_SIZE_T*)(chunk2mem(oldp));
5048 d = (INTERNAL_SIZE_T*)(newmem);
5049 ncopies = copysize / sizeof(INTERNAL_SIZE_T);
5050 assert(ncopies >= 3);
5052 if (ncopies > 9)
5053 MALLOC_COPY(d, s, copysize);
5055 else {
5056 *(d+0) = *(s+0);
5057 *(d+1) = *(s+1);
5058 *(d+2) = *(s+2);
5059 if (ncopies > 4) {
5060 *(d+3) = *(s+3);
5061 *(d+4) = *(s+4);
5062 if (ncopies > 6) {
5063 *(d+5) = *(s+5);
5064 *(d+6) = *(s+6);
5065 if (ncopies > 8) {
5066 *(d+7) = *(s+7);
5067 *(d+8) = *(s+8);
5073 _int_free(av, oldp);
5074 check_inuse_chunk(av, newp);
5075 return chunk2mem(newp);
5080 /* If possible, free extra space in old or extended chunk */
5082 assert((unsigned long)(newsize) >= (unsigned long)(nb));
5084 remainder_size = newsize - nb;
5086 if (remainder_size < MINSIZE) { /* not enough extra to split off */
5087 set_head_size(newp, newsize | (av != &main_arena ? NON_MAIN_ARENA : 0));
5088 set_inuse_bit_at_offset(newp, newsize);
5090 else { /* split remainder */
5091 remainder = chunk_at_offset(newp, nb);
5092 set_head_size(newp, nb | (av != &main_arena ? NON_MAIN_ARENA : 0));
5093 set_head(remainder, remainder_size | PREV_INUSE |
5094 (av != &main_arena ? NON_MAIN_ARENA : 0));
5095 /* Mark remainder as inuse so free() won't complain */
5096 set_inuse_bit_at_offset(remainder, remainder_size);
5097 _int_free(av, remainder);
5100 check_inuse_chunk(av, newp);
5101 return chunk2mem(newp);
5105 Handle mmap cases
5108 else {
5109 #if HAVE_MMAP
5111 #if HAVE_MREMAP
5112 INTERNAL_SIZE_T offset = oldp->prev_size;
5113 size_t pagemask = mp_.pagesize - 1;
5114 char *cp;
5115 unsigned long sum;
5117 /* Note the extra SIZE_SZ overhead */
5118 newsize = (nb + offset + SIZE_SZ + pagemask) & ~pagemask;
5120 /* don't need to remap if still within same page */
5121 if (oldsize == newsize - offset)
5122 return chunk2mem(oldp);
5124 cp = (char*)mremap((char*)oldp - offset, oldsize + offset, newsize, 1);
5126 if (cp != MAP_FAILED) {
5128 newp = (mchunkptr)(cp + offset);
5129 set_head(newp, (newsize - offset)|IS_MMAPPED);
5131 assert(aligned_OK(chunk2mem(newp)));
5132 assert((newp->prev_size == offset));
5134 /* update statistics */
5135 sum = mp_.mmapped_mem += newsize - oldsize;
5136 if (sum > (unsigned long)(mp_.max_mmapped_mem))
5137 mp_.max_mmapped_mem = sum;
5138 #ifdef NO_THREADS
5139 sum += main_arena.system_mem;
5140 if (sum > (unsigned long)(mp_.max_total_mem))
5141 mp_.max_total_mem = sum;
5142 #endif
5144 return chunk2mem(newp);
5146 #endif
5148 /* Note the extra SIZE_SZ overhead. */
5149 if ((unsigned long)(oldsize) >= (unsigned long)(nb + SIZE_SZ))
5150 newmem = chunk2mem(oldp); /* do nothing */
5151 else {
5152 /* Must alloc, copy, free. */
5153 newmem = _int_malloc(av, nb - MALLOC_ALIGN_MASK);
5154 if (newmem != 0) {
5155 MALLOC_COPY(newmem, chunk2mem(oldp), oldsize - 2*SIZE_SZ);
5156 _int_free(av, oldp);
5159 return newmem;
5161 #else
5162 /* If !HAVE_MMAP, but chunk_is_mmapped, user must have overwritten mem */
5163 check_malloc_state(av);
5164 MALLOC_FAILURE_ACTION;
5165 return 0;
5166 #endif
5171 ------------------------------ memalign ------------------------------
5174 static Void_t*
5175 _int_memalign(mstate av, size_t alignment, size_t bytes)
5177 INTERNAL_SIZE_T nb; /* padded request size */
5178 char* m; /* memory returned by malloc call */
5179 mchunkptr p; /* corresponding chunk */
5180 char* brk; /* alignment point within p */
5181 mchunkptr newp; /* chunk to return */
5182 INTERNAL_SIZE_T newsize; /* its size */
5183 INTERNAL_SIZE_T leadsize; /* leading space before alignment point */
5184 mchunkptr remainder; /* spare room at end to split off */
5185 unsigned long remainder_size; /* its size */
5186 INTERNAL_SIZE_T size;
5188 /* If need less alignment than we give anyway, just relay to malloc */
5190 if (alignment <= MALLOC_ALIGNMENT) return _int_malloc(av, bytes);
5192 /* Otherwise, ensure that it is at least a minimum chunk size */
5194 if (alignment < MINSIZE) alignment = MINSIZE;
5196 /* Make sure alignment is power of 2 (in case MINSIZE is not). */
5197 if ((alignment & (alignment - 1)) != 0) {
5198 size_t a = MALLOC_ALIGNMENT * 2;
5199 while ((unsigned long)a < (unsigned long)alignment) a <<= 1;
5200 alignment = a;
5203 checked_request2size(bytes, nb);
5206 Strategy: find a spot within that chunk that meets the alignment
5207 request, and then possibly free the leading and trailing space.
5211 /* Call malloc with worst case padding to hit alignment. */
5213 m = (char*)(_int_malloc(av, nb + alignment + MINSIZE));
5215 if (m == 0) return 0; /* propagate failure */
5217 p = mem2chunk(m);
5219 if ((((unsigned long)(m)) % alignment) != 0) { /* misaligned */
5222 Find an aligned spot inside chunk. Since we need to give back
5223 leading space in a chunk of at least MINSIZE, if the first
5224 calculation places us at a spot with less than MINSIZE leader,
5225 we can move to the next aligned spot -- we've allocated enough
5226 total room so that this is always possible.
5229 brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) &
5230 -((signed long) alignment));
5231 if ((unsigned long)(brk - (char*)(p)) < MINSIZE)
5232 brk += alignment;
5234 newp = (mchunkptr)brk;
5235 leadsize = brk - (char*)(p);
5236 newsize = chunksize(p) - leadsize;
5238 /* For mmapped chunks, just adjust offset */
5239 if (chunk_is_mmapped(p)) {
5240 newp->prev_size = p->prev_size + leadsize;
5241 set_head(newp, newsize|IS_MMAPPED);
5242 return chunk2mem(newp);
5245 /* Otherwise, give back leader, use the rest */
5246 set_head(newp, newsize | PREV_INUSE |
5247 (av != &main_arena ? NON_MAIN_ARENA : 0));
5248 set_inuse_bit_at_offset(newp, newsize);
5249 set_head_size(p, leadsize | (av != &main_arena ? NON_MAIN_ARENA : 0));
5250 _int_free(av, p);
5251 p = newp;
5253 assert (newsize >= nb &&
5254 (((unsigned long)(chunk2mem(p))) % alignment) == 0);
5257 /* Also give back spare room at the end */
5258 if (!chunk_is_mmapped(p)) {
5259 size = chunksize(p);
5260 if ((unsigned long)(size) > (unsigned long)(nb + MINSIZE)) {
5261 remainder_size = size - nb;
5262 remainder = chunk_at_offset(p, nb);
5263 set_head(remainder, remainder_size | PREV_INUSE |
5264 (av != &main_arena ? NON_MAIN_ARENA : 0));
5265 set_head_size(p, nb);
5266 _int_free(av, remainder);
5270 check_inuse_chunk(av, p);
5271 return chunk2mem(p);
5274 #if 0
5276 ------------------------------ calloc ------------------------------
5279 #if __STD_C
5280 Void_t* cALLOc(size_t n_elements, size_t elem_size)
5281 #else
5282 Void_t* cALLOc(n_elements, elem_size) size_t n_elements; size_t elem_size;
5283 #endif
5285 mchunkptr p;
5286 unsigned long clearsize;
5287 unsigned long nclears;
5288 INTERNAL_SIZE_T* d;
5290 Void_t* mem = mALLOc(n_elements * elem_size);
5292 if (mem != 0) {
5293 p = mem2chunk(mem);
5295 #if MMAP_CLEARS
5296 if (!chunk_is_mmapped(p)) /* don't need to clear mmapped space */
5297 #endif
5300 Unroll clear of <= 36 bytes (72 if 8byte sizes)
5301 We know that contents have an odd number of
5302 INTERNAL_SIZE_T-sized words; minimally 3.
5305 d = (INTERNAL_SIZE_T*)mem;
5306 clearsize = chunksize(p) - SIZE_SZ;
5307 nclears = clearsize / sizeof(INTERNAL_SIZE_T);
5308 assert(nclears >= 3);
5310 if (nclears > 9)
5311 MALLOC_ZERO(d, clearsize);
5313 else {
5314 *(d+0) = 0;
5315 *(d+1) = 0;
5316 *(d+2) = 0;
5317 if (nclears > 4) {
5318 *(d+3) = 0;
5319 *(d+4) = 0;
5320 if (nclears > 6) {
5321 *(d+5) = 0;
5322 *(d+6) = 0;
5323 if (nclears > 8) {
5324 *(d+7) = 0;
5325 *(d+8) = 0;
5332 return mem;
5334 #endif /* 0 */
5336 #ifndef _LIBC
5338 ------------------------- independent_calloc -------------------------
5341 Void_t**
5342 #if __STD_C
5343 _int_icalloc(mstate av, size_t n_elements, size_t elem_size, Void_t* chunks[])
5344 #else
5345 _int_icalloc(av, n_elements, elem_size, chunks)
5346 mstate av; size_t n_elements; size_t elem_size; Void_t* chunks[];
5347 #endif
5349 size_t sz = elem_size; /* serves as 1-element array */
5350 /* opts arg of 3 means all elements are same size, and should be cleared */
5351 return iALLOc(av, n_elements, &sz, 3, chunks);
5355 ------------------------- independent_comalloc -------------------------
5358 Void_t**
5359 #if __STD_C
5360 _int_icomalloc(mstate av, size_t n_elements, size_t sizes[], Void_t* chunks[])
5361 #else
5362 _int_icomalloc(av, n_elements, sizes, chunks)
5363 mstate av; size_t n_elements; size_t sizes[]; Void_t* chunks[];
5364 #endif
5366 return iALLOc(av, n_elements, sizes, 0, chunks);
5371 ------------------------------ ialloc ------------------------------
5372 ialloc provides common support for independent_X routines, handling all of
5373 the combinations that can result.
5375 The opts arg has:
5376 bit 0 set if all elements are same size (using sizes[0])
5377 bit 1 set if elements should be zeroed
5381 static Void_t**
5382 #if __STD_C
5383 iALLOc(mstate av, size_t n_elements, size_t* sizes, int opts, Void_t* chunks[])
5384 #else
5385 iALLOc(av, n_elements, sizes, opts, chunks)
5386 mstate av; size_t n_elements; size_t* sizes; int opts; Void_t* chunks[];
5387 #endif
5389 INTERNAL_SIZE_T element_size; /* chunksize of each element, if all same */
5390 INTERNAL_SIZE_T contents_size; /* total size of elements */
5391 INTERNAL_SIZE_T array_size; /* request size of pointer array */
5392 Void_t* mem; /* malloced aggregate space */
5393 mchunkptr p; /* corresponding chunk */
5394 INTERNAL_SIZE_T remainder_size; /* remaining bytes while splitting */
5395 Void_t** marray; /* either "chunks" or malloced ptr array */
5396 mchunkptr array_chunk; /* chunk for malloced ptr array */
5397 int mmx; /* to disable mmap */
5398 INTERNAL_SIZE_T size;
5399 INTERNAL_SIZE_T size_flags;
5400 size_t i;
5402 /* Ensure initialization/consolidation */
5403 if (have_fastchunks(av)) malloc_consolidate(av);
5405 /* compute array length, if needed */
5406 if (chunks != 0) {
5407 if (n_elements == 0)
5408 return chunks; /* nothing to do */
5409 marray = chunks;
5410 array_size = 0;
5412 else {
5413 /* if empty req, must still return chunk representing empty array */
5414 if (n_elements == 0)
5415 return (Void_t**) _int_malloc(av, 0);
5416 marray = 0;
5417 array_size = request2size(n_elements * (sizeof(Void_t*)));
5420 /* compute total element size */
5421 if (opts & 0x1) { /* all-same-size */
5422 element_size = request2size(*sizes);
5423 contents_size = n_elements * element_size;
5425 else { /* add up all the sizes */
5426 element_size = 0;
5427 contents_size = 0;
5428 for (i = 0; i != n_elements; ++i)
5429 contents_size += request2size(sizes[i]);
5432 /* subtract out alignment bytes from total to minimize overallocation */
5433 size = contents_size + array_size - MALLOC_ALIGN_MASK;
5436 Allocate the aggregate chunk.
5437 But first disable mmap so malloc won't use it, since
5438 we would not be able to later free/realloc space internal
5439 to a segregated mmap region.
5441 mmx = mp_.n_mmaps_max; /* disable mmap */
5442 mp_.n_mmaps_max = 0;
5443 mem = _int_malloc(av, size);
5444 mp_.n_mmaps_max = mmx; /* reset mmap */
5445 if (mem == 0)
5446 return 0;
5448 p = mem2chunk(mem);
5449 assert(!chunk_is_mmapped(p));
5450 remainder_size = chunksize(p);
5452 if (opts & 0x2) { /* optionally clear the elements */
5453 MALLOC_ZERO(mem, remainder_size - SIZE_SZ - array_size);
5456 size_flags = PREV_INUSE | (av != &main_arena ? NON_MAIN_ARENA : 0);
5458 /* If not provided, allocate the pointer array as final part of chunk */
5459 if (marray == 0) {
5460 array_chunk = chunk_at_offset(p, contents_size);
5461 marray = (Void_t**) (chunk2mem(array_chunk));
5462 set_head(array_chunk, (remainder_size - contents_size) | size_flags);
5463 remainder_size = contents_size;
5466 /* split out elements */
5467 for (i = 0; ; ++i) {
5468 marray[i] = chunk2mem(p);
5469 if (i != n_elements-1) {
5470 if (element_size != 0)
5471 size = element_size;
5472 else
5473 size = request2size(sizes[i]);
5474 remainder_size -= size;
5475 set_head(p, size | size_flags);
5476 p = chunk_at_offset(p, size);
5478 else { /* the final element absorbs any overallocation slop */
5479 set_head(p, remainder_size | size_flags);
5480 break;
5484 #if MALLOC_DEBUG
5485 if (marray != chunks) {
5486 /* final element must have exactly exhausted chunk */
5487 if (element_size != 0)
5488 assert(remainder_size == element_size);
5489 else
5490 assert(remainder_size == request2size(sizes[i]));
5491 check_inuse_chunk(av, mem2chunk(marray));
5494 for (i = 0; i != n_elements; ++i)
5495 check_inuse_chunk(av, mem2chunk(marray[i]));
5496 #endif
5498 return marray;
5500 #endif /* _LIBC */
5504 ------------------------------ valloc ------------------------------
5507 static Void_t*
5508 #if __STD_C
5509 _int_valloc(mstate av, size_t bytes)
5510 #else
5511 _int_valloc(av, bytes) mstate av; size_t bytes;
5512 #endif
5514 /* Ensure initialization/consolidation */
5515 if (have_fastchunks(av)) malloc_consolidate(av);
5516 return _int_memalign(av, mp_.pagesize, bytes);
5520 ------------------------------ pvalloc ------------------------------
5524 static Void_t*
5525 #if __STD_C
5526 _int_pvalloc(mstate av, size_t bytes)
5527 #else
5528 _int_pvalloc(av, bytes) mstate av, size_t bytes;
5529 #endif
5531 size_t pagesz;
5533 /* Ensure initialization/consolidation */
5534 if (have_fastchunks(av)) malloc_consolidate(av);
5535 pagesz = mp_.pagesize;
5536 return _int_memalign(av, pagesz, (bytes + pagesz - 1) & ~(pagesz - 1));
5541 ------------------------------ malloc_trim ------------------------------
5544 #if __STD_C
5545 static int mTRIm(mstate av, size_t pad)
5546 #else
5547 static int mTRIm(av, pad) mstate av; size_t pad;
5548 #endif
5550 /* Ensure initialization/consolidation */
5551 malloc_consolidate (av);
5553 const size_t ps = mp_.pagesize;
5554 int psindex = bin_index (ps);
5555 const size_t psm1 = ps - 1;
5557 int result = 0;
5558 for (int i = 1; i < NBINS; ++i)
5559 if (i == 1 || i >= psindex)
5561 mbinptr bin = bin_at (av, i);
5563 for (mchunkptr p = last (bin); p != bin; p = p->bk)
5565 INTERNAL_SIZE_T size = chunksize (p);
5567 if (size > psm1 + sizeof (struct malloc_chunk))
5569 /* See whether the chunk contains at least one unused page. */
5570 char *paligned_mem = (char *) (((uintptr_t) p
5571 + sizeof (struct malloc_chunk)
5572 + psm1) & ~psm1);
5574 assert ((char *) chunk2mem (p) + 4 * SIZE_SZ <= paligned_mem);
5575 assert ((char *) p + size > paligned_mem);
5577 /* This is the size we could potentially free. */
5578 size -= paligned_mem - (char *) p;
5580 if (size > psm1)
5582 #ifdef MALLOC_DEBUG
5583 /* When debugging we simulate destroying the memory
5584 content. */
5585 memset (paligned_mem, 0x89, size & ~psm1);
5586 #endif
5587 madvise (paligned_mem, size & ~psm1, MADV_DONTNEED);
5589 result = 1;
5595 #ifndef MORECORE_CANNOT_TRIM
5596 return result | (av == &main_arena ? sYSTRIm (pad, av) : 0);
5597 #else
5598 return result;
5599 #endif
5604 ------------------------- malloc_usable_size -------------------------
5607 #if __STD_C
5608 size_t mUSABLe(Void_t* mem)
5609 #else
5610 size_t mUSABLe(mem) Void_t* mem;
5611 #endif
5613 mchunkptr p;
5614 if (mem != 0) {
5615 p = mem2chunk(mem);
5616 if (chunk_is_mmapped(p))
5617 return chunksize(p) - 2*SIZE_SZ;
5618 else if (inuse(p))
5619 return chunksize(p) - SIZE_SZ;
5621 return 0;
5625 ------------------------------ mallinfo ------------------------------
5628 struct mallinfo mALLINFo(mstate av)
5630 struct mallinfo mi;
5631 size_t i;
5632 mbinptr b;
5633 mchunkptr p;
5634 INTERNAL_SIZE_T avail;
5635 INTERNAL_SIZE_T fastavail;
5636 int nblocks;
5637 int nfastblocks;
5639 /* Ensure initialization */
5640 if (av->top == 0) malloc_consolidate(av);
5642 check_malloc_state(av);
5644 /* Account for top */
5645 avail = chunksize(av->top);
5646 nblocks = 1; /* top always exists */
5648 /* traverse fastbins */
5649 nfastblocks = 0;
5650 fastavail = 0;
5652 for (i = 0; i < NFASTBINS; ++i) {
5653 for (p = av->fastbins[i]; p != 0; p = p->fd) {
5654 ++nfastblocks;
5655 fastavail += chunksize(p);
5659 avail += fastavail;
5661 /* traverse regular bins */
5662 for (i = 1; i < NBINS; ++i) {
5663 b = bin_at(av, i);
5664 for (p = last(b); p != b; p = p->bk) {
5665 ++nblocks;
5666 avail += chunksize(p);
5670 mi.smblks = nfastblocks;
5671 mi.ordblks = nblocks;
5672 mi.fordblks = avail;
5673 mi.uordblks = av->system_mem - avail;
5674 mi.arena = av->system_mem;
5675 mi.hblks = mp_.n_mmaps;
5676 mi.hblkhd = mp_.mmapped_mem;
5677 mi.fsmblks = fastavail;
5678 mi.keepcost = chunksize(av->top);
5679 mi.usmblks = mp_.max_total_mem;
5680 return mi;
5684 ------------------------------ malloc_stats ------------------------------
5687 void mSTATs()
5689 int i;
5690 mstate ar_ptr;
5691 struct mallinfo mi;
5692 unsigned int in_use_b = mp_.mmapped_mem, system_b = in_use_b;
5693 #if THREAD_STATS
5694 long stat_lock_direct = 0, stat_lock_loop = 0, stat_lock_wait = 0;
5695 #endif
5697 if(__malloc_initialized < 0)
5698 ptmalloc_init ();
5699 #ifdef _LIBC
5700 _IO_flockfile (stderr);
5701 int old_flags2 = ((_IO_FILE *) stderr)->_flags2;
5702 ((_IO_FILE *) stderr)->_flags2 |= _IO_FLAGS2_NOTCANCEL;
5703 #endif
5704 for (i=0, ar_ptr = &main_arena;; i++) {
5705 (void)mutex_lock(&ar_ptr->mutex);
5706 mi = mALLINFo(ar_ptr);
5707 fprintf(stderr, "Arena %d:\n", i);
5708 fprintf(stderr, "system bytes = %10u\n", (unsigned int)mi.arena);
5709 fprintf(stderr, "in use bytes = %10u\n", (unsigned int)mi.uordblks);
5710 #if MALLOC_DEBUG > 1
5711 if (i > 0)
5712 dump_heap(heap_for_ptr(top(ar_ptr)));
5713 #endif
5714 system_b += mi.arena;
5715 in_use_b += mi.uordblks;
5716 #if THREAD_STATS
5717 stat_lock_direct += ar_ptr->stat_lock_direct;
5718 stat_lock_loop += ar_ptr->stat_lock_loop;
5719 stat_lock_wait += ar_ptr->stat_lock_wait;
5720 #endif
5721 (void)mutex_unlock(&ar_ptr->mutex);
5722 ar_ptr = ar_ptr->next;
5723 if(ar_ptr == &main_arena) break;
5725 #if HAVE_MMAP
5726 fprintf(stderr, "Total (incl. mmap):\n");
5727 #else
5728 fprintf(stderr, "Total:\n");
5729 #endif
5730 fprintf(stderr, "system bytes = %10u\n", system_b);
5731 fprintf(stderr, "in use bytes = %10u\n", in_use_b);
5732 #ifdef NO_THREADS
5733 fprintf(stderr, "max system bytes = %10u\n", (unsigned int)mp_.max_total_mem);
5734 #endif
5735 #if HAVE_MMAP
5736 fprintf(stderr, "max mmap regions = %10u\n", (unsigned int)mp_.max_n_mmaps);
5737 fprintf(stderr, "max mmap bytes = %10lu\n",
5738 (unsigned long)mp_.max_mmapped_mem);
5739 #endif
5740 #if THREAD_STATS
5741 fprintf(stderr, "heaps created = %10d\n", stat_n_heaps);
5742 fprintf(stderr, "locked directly = %10ld\n", stat_lock_direct);
5743 fprintf(stderr, "locked in loop = %10ld\n", stat_lock_loop);
5744 fprintf(stderr, "locked waiting = %10ld\n", stat_lock_wait);
5745 fprintf(stderr, "locked total = %10ld\n",
5746 stat_lock_direct + stat_lock_loop + stat_lock_wait);
5747 #endif
5748 #ifdef _LIBC
5749 ((_IO_FILE *) stderr)->_flags2 |= old_flags2;
5750 _IO_funlockfile (stderr);
5751 #endif
5756 ------------------------------ mallopt ------------------------------
5759 #if __STD_C
5760 int mALLOPt(int param_number, int value)
5761 #else
5762 int mALLOPt(param_number, value) int param_number; int value;
5763 #endif
5765 mstate av = &main_arena;
5766 int res = 1;
5768 if(__malloc_initialized < 0)
5769 ptmalloc_init ();
5770 (void)mutex_lock(&av->mutex);
5771 /* Ensure initialization/consolidation */
5772 malloc_consolidate(av);
5774 switch(param_number) {
5775 case M_MXFAST:
5776 if (value >= 0 && value <= MAX_FAST_SIZE) {
5777 set_max_fast(value);
5779 else
5780 res = 0;
5781 break;
5783 case M_TRIM_THRESHOLD:
5784 mp_.trim_threshold = value;
5785 mp_.no_dyn_threshold = 1;
5786 break;
5788 case M_TOP_PAD:
5789 mp_.top_pad = value;
5790 mp_.no_dyn_threshold = 1;
5791 break;
5793 case M_MMAP_THRESHOLD:
5794 #if USE_ARENAS
5795 /* Forbid setting the threshold too high. */
5796 if((unsigned long)value > HEAP_MAX_SIZE/2)
5797 res = 0;
5798 else
5799 #endif
5800 mp_.mmap_threshold = value;
5801 mp_.no_dyn_threshold = 1;
5802 break;
5804 case M_MMAP_MAX:
5805 #if !HAVE_MMAP
5806 if (value != 0)
5807 res = 0;
5808 else
5809 #endif
5810 mp_.n_mmaps_max = value;
5811 mp_.no_dyn_threshold = 1;
5812 break;
5814 case M_CHECK_ACTION:
5815 check_action = value;
5816 break;
5818 case M_PERTURB:
5819 perturb_byte = value;
5820 break;
5822 (void)mutex_unlock(&av->mutex);
5823 return res;
5828 -------------------- Alternative MORECORE functions --------------------
5833 General Requirements for MORECORE.
5835 The MORECORE function must have the following properties:
5837 If MORECORE_CONTIGUOUS is false:
5839 * MORECORE must allocate in multiples of pagesize. It will
5840 only be called with arguments that are multiples of pagesize.
5842 * MORECORE(0) must return an address that is at least
5843 MALLOC_ALIGNMENT aligned. (Page-aligning always suffices.)
5845 else (i.e. If MORECORE_CONTIGUOUS is true):
5847 * Consecutive calls to MORECORE with positive arguments
5848 return increasing addresses, indicating that space has been
5849 contiguously extended.
5851 * MORECORE need not allocate in multiples of pagesize.
5852 Calls to MORECORE need not have args of multiples of pagesize.
5854 * MORECORE need not page-align.
5856 In either case:
5858 * MORECORE may allocate more memory than requested. (Or even less,
5859 but this will generally result in a malloc failure.)
5861 * MORECORE must not allocate memory when given argument zero, but
5862 instead return one past the end address of memory from previous
5863 nonzero call. This malloc does NOT call MORECORE(0)
5864 until at least one call with positive arguments is made, so
5865 the initial value returned is not important.
5867 * Even though consecutive calls to MORECORE need not return contiguous
5868 addresses, it must be OK for malloc'ed chunks to span multiple
5869 regions in those cases where they do happen to be contiguous.
5871 * MORECORE need not handle negative arguments -- it may instead
5872 just return MORECORE_FAILURE when given negative arguments.
5873 Negative arguments are always multiples of pagesize. MORECORE
5874 must not misinterpret negative args as large positive unsigned
5875 args. You can suppress all such calls from even occurring by defining
5876 MORECORE_CANNOT_TRIM,
5878 There is some variation across systems about the type of the
5879 argument to sbrk/MORECORE. If size_t is unsigned, then it cannot
5880 actually be size_t, because sbrk supports negative args, so it is
5881 normally the signed type of the same width as size_t (sometimes
5882 declared as "intptr_t", and sometimes "ptrdiff_t"). It doesn't much
5883 matter though. Internally, we use "long" as arguments, which should
5884 work across all reasonable possibilities.
5886 Additionally, if MORECORE ever returns failure for a positive
5887 request, and HAVE_MMAP is true, then mmap is used as a noncontiguous
5888 system allocator. This is a useful backup strategy for systems with
5889 holes in address spaces -- in this case sbrk cannot contiguously
5890 expand the heap, but mmap may be able to map noncontiguous space.
5892 If you'd like mmap to ALWAYS be used, you can define MORECORE to be
5893 a function that always returns MORECORE_FAILURE.
5895 If you are using this malloc with something other than sbrk (or its
5896 emulation) to supply memory regions, you probably want to set
5897 MORECORE_CONTIGUOUS as false. As an example, here is a custom
5898 allocator kindly contributed for pre-OSX macOS. It uses virtually
5899 but not necessarily physically contiguous non-paged memory (locked
5900 in, present and won't get swapped out). You can use it by
5901 uncommenting this section, adding some #includes, and setting up the
5902 appropriate defines above:
5904 #define MORECORE osMoreCore
5905 #define MORECORE_CONTIGUOUS 0
5907 There is also a shutdown routine that should somehow be called for
5908 cleanup upon program exit.
5910 #define MAX_POOL_ENTRIES 100
5911 #define MINIMUM_MORECORE_SIZE (64 * 1024)
5912 static int next_os_pool;
5913 void *our_os_pools[MAX_POOL_ENTRIES];
5915 void *osMoreCore(int size)
5917 void *ptr = 0;
5918 static void *sbrk_top = 0;
5920 if (size > 0)
5922 if (size < MINIMUM_MORECORE_SIZE)
5923 size = MINIMUM_MORECORE_SIZE;
5924 if (CurrentExecutionLevel() == kTaskLevel)
5925 ptr = PoolAllocateResident(size + RM_PAGE_SIZE, 0);
5926 if (ptr == 0)
5928 return (void *) MORECORE_FAILURE;
5930 // save ptrs so they can be freed during cleanup
5931 our_os_pools[next_os_pool] = ptr;
5932 next_os_pool++;
5933 ptr = (void *) ((((unsigned long) ptr) + RM_PAGE_MASK) & ~RM_PAGE_MASK);
5934 sbrk_top = (char *) ptr + size;
5935 return ptr;
5937 else if (size < 0)
5939 // we don't currently support shrink behavior
5940 return (void *) MORECORE_FAILURE;
5942 else
5944 return sbrk_top;
5948 // cleanup any allocated memory pools
5949 // called as last thing before shutting down driver
5951 void osCleanupMem(void)
5953 void **ptr;
5955 for (ptr = our_os_pools; ptr < &our_os_pools[MAX_POOL_ENTRIES]; ptr++)
5956 if (*ptr)
5958 PoolDeallocate(*ptr);
5959 *ptr = 0;
5966 /* Helper code. */
5968 extern char **__libc_argv attribute_hidden;
5970 static void
5971 malloc_printerr(int action, const char *str, void *ptr)
5973 if ((action & 5) == 5)
5974 __libc_message (action & 2, "%s\n", str);
5975 else if (action & 1)
5977 char buf[2 * sizeof (uintptr_t) + 1];
5979 buf[sizeof (buf) - 1] = '\0';
5980 char *cp = _itoa_word ((uintptr_t) ptr, &buf[sizeof (buf) - 1], 16, 0);
5981 while (cp > buf)
5982 *--cp = '0';
5984 __libc_message (action & 2,
5985 "*** glibc detected *** %s: %s: 0x%s ***\n",
5986 __libc_argv[0] ?: "<unknown>", str, cp);
5988 else if (action & 2)
5989 abort ();
5992 #ifdef _LIBC
5993 # include <sys/param.h>
5995 /* We need a wrapper function for one of the additions of POSIX. */
5997 __posix_memalign (void **memptr, size_t alignment, size_t size)
5999 void *mem;
6000 __malloc_ptr_t (*hook) __MALLOC_PMT ((size_t, size_t,
6001 __const __malloc_ptr_t)) =
6002 __memalign_hook;
6004 /* Test whether the SIZE argument is valid. It must be a power of
6005 two multiple of sizeof (void *). */
6006 if (alignment % sizeof (void *) != 0
6007 || !powerof2 (alignment / sizeof (void *)) != 0
6008 || alignment == 0)
6009 return EINVAL;
6011 /* Call the hook here, so that caller is posix_memalign's caller
6012 and not posix_memalign itself. */
6013 if (__builtin_expect (hook != NULL, 0))
6014 mem = (*hook)(alignment, size, RETURN_ADDRESS (0));
6015 else
6016 mem = public_mEMALIGn (alignment, size);
6018 if (mem != NULL) {
6019 *memptr = mem;
6020 return 0;
6023 return ENOMEM;
6025 weak_alias (__posix_memalign, posix_memalign)
6027 strong_alias (__libc_calloc, __calloc) weak_alias (__libc_calloc, calloc)
6028 strong_alias (__libc_free, __cfree) weak_alias (__libc_free, cfree)
6029 strong_alias (__libc_free, __free) strong_alias (__libc_free, free)
6030 strong_alias (__libc_malloc, __malloc) strong_alias (__libc_malloc, malloc)
6031 strong_alias (__libc_memalign, __memalign)
6032 weak_alias (__libc_memalign, memalign)
6033 strong_alias (__libc_realloc, __realloc) strong_alias (__libc_realloc, realloc)
6034 strong_alias (__libc_valloc, __valloc) weak_alias (__libc_valloc, valloc)
6035 strong_alias (__libc_pvalloc, __pvalloc) weak_alias (__libc_pvalloc, pvalloc)
6036 strong_alias (__libc_mallinfo, __mallinfo)
6037 weak_alias (__libc_mallinfo, mallinfo)
6038 strong_alias (__libc_mallopt, __mallopt) weak_alias (__libc_mallopt, mallopt)
6040 weak_alias (__malloc_stats, malloc_stats)
6041 weak_alias (__malloc_usable_size, malloc_usable_size)
6042 weak_alias (__malloc_trim, malloc_trim)
6043 weak_alias (__malloc_get_state, malloc_get_state)
6044 weak_alias (__malloc_set_state, malloc_set_state)
6046 #endif /* _LIBC */
6048 /* ------------------------------------------------------------
6049 History:
6051 [see ftp://g.oswego.edu/pub/misc/malloc.c for the history of dlmalloc]
6055 * Local variables:
6056 * c-basic-offset: 2
6057 * End: