1 /*
2 Copyright (c) 1990 Regents of the University of California.
3 All rights reserved.
4 */
5 #ifdef MALLOC_PROVIDED
6 int _dummy_mallocr = 1;
7 #else
8 /* ---------- To make a malloc.h, start cutting here ------------ */
9
10 /*
11 A version of malloc/free/realloc written by Doug Lea and released to the
12 public domain. Send questions/comments/complaints/performance data
13 to dl@cs.oswego.edu
14
15 * VERSION 2.6.5 Wed Jun 17 15:55:16 1998 Doug Lea (dl at gee)
16
17 Note: There may be an updated version of this malloc obtainable at
18 ftp://g.oswego.edu/pub/misc/malloc.c
19 Check before installing!
20
21 Note: This version differs from 2.6.4 only by correcting a
22 statement ordering error that could cause failures only
23 when calls to this malloc are interposed with calls to
24 other memory allocators.
25
26 * Why use this malloc?
27
28 This is not the fastest, most space-conserving, most portable, or
29 most tunable malloc ever written. However it is among the fastest
30 while also being among the most space-conserving, portable and tunable.
31 Consistent balance across these factors results in a good general-purpose
32 allocator. For a high-level description, see
33 http://g.oswego.edu/dl/html/malloc.html
34
35 * Synopsis of public routines
36
37 (Much fuller descriptions are contained in the program documentation below.)
38
39 malloc(size_t n);
40 Return a pointer to a newly allocated chunk of at least n bytes, or null
41 if no space is available.
42 free(Void_t* p);
43 Release the chunk of memory pointed to by p, or no effect if p is null.
44 realloc(Void_t* p, size_t n);
45 Return a pointer to a chunk of size n that contains the same data
46 as does chunk p up to the minimum of (n, p's size) bytes, or null
47 if no space is available. The returned pointer may or may not be
48 the same as p. If p is null, equivalent to malloc. Unless the
49 #define REALLOC_ZERO_BYTES_FREES below is set, realloc with a
50 size argument of zero (re)allocates a minimum-sized chunk.
51 memalign(size_t alignment, size_t n);
52 Return a pointer to a newly allocated chunk of n bytes, aligned
53 in accord with the alignment argument, which must be a power of
54 two.
55 valloc(size_t n);
56 Equivalent to memalign(pagesize, n), where pagesize is the page
57 size of the system (or as near to this as can be figured out from
58 all the includes/defines below.)
59 pvalloc(size_t n);
60 Equivalent to valloc(minimum-page-that-holds(n)), that is,
61 round up n to nearest pagesize.
62 calloc(size_t unit, size_t quantity);
63 Returns a pointer to quantity * unit bytes, with all locations
64 set to zero.
65 cfree(Void_t* p);
66 Equivalent to free(p).
67 malloc_trim(size_t pad);
68 Release all but pad bytes of freed top-most memory back
69 to the system. Return 1 if successful, else 0.
70 malloc_usable_size(Void_t* p);
71 Report the number usable allocated bytes associated with allocated
72 chunk p. This may or may not report more bytes than were requested,
73 due to alignment and minimum size constraints.
74 malloc_stats();
75 Prints brief summary statistics on stderr.
76 mallinfo()
77 Returns (by copy) a struct containing various summary statistics.
78 mallopt(int parameter_number, int parameter_value)
79 Changes one of the tunable parameters described below. Returns
80 1 if successful in changing the parameter, else 0.
81
82 * Vital statistics:
83
84 Alignment: 8-byte
85 8 byte alignment is currently hardwired into the design. This
86 seems to suffice for all current machines and C compilers.
87
88 Assumed pointer representation: 4 or 8 bytes
89 Code for 8-byte pointers is untested by me but has worked
90 reliably by Wolfram Gloger, who contributed most of the
91 changes supporting this.
92
93 Assumed size_t representation: 4 or 8 bytes
94 Note that size_t is allowed to be 4 bytes even if pointers are 8.
95
96 Minimum overhead per allocated chunk: 4 or 8 bytes
97 Each malloced chunk has a hidden overhead of 4 bytes holding size
98 and status information.
99
100 Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
101 8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
102
103 When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
104 ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
105 needed; 4 (8) for a trailing size field
106 and 8 (16) bytes for free list pointers. Thus, the minimum
107 allocatable size is 16/24/32 bytes.
108
109 Even a request for zero bytes (i.e., malloc(0)) returns a
110 pointer to something of the minimum allocatable size.
111
112 Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes
113 8-byte size_t: 2^63 - 16 bytes
114
115 It is assumed that (possibly signed) size_t bit values suffice to
116 represent chunk sizes. `Possibly signed' is due to the fact
117 that `size_t' may be defined on a system as either a signed or
118 an unsigned type. To be conservative, values that would appear
119 as negative numbers are avoided.
120 Requests for sizes with a negative sign bit will return a
121 minimum-sized chunk.
122
123 Maximum overhead wastage per allocated chunk: normally 15 bytes
124
125 Alignnment demands, plus the minimum allocatable size restriction
126 make the normal worst-case wastage 15 bytes (i.e., up to 15
127 more bytes will be allocated than were requested in malloc), with
128 two exceptions:
129 1. Because requests for zero bytes allocate non-zero space,
130 the worst case wastage for a request of zero bytes is 24 bytes.
131 2. For requests >= mmap_threshold that are serviced via
132 mmap(), the worst case wastage is 8 bytes plus the remainder
133 from a system page (the minimal mmap unit); typically 4096 bytes.
134
135 * Limitations
136
137 Here are some features that are NOT currently supported
138
139 * No user-definable hooks for callbacks and the like.
140 * No automated mechanism for fully checking that all accesses
141 to malloced memory stay within their bounds.
142 * No support for compaction.
143
144 * Synopsis of compile-time options:
145
146 People have reported using previous versions of this malloc on all
147 versions of Unix, sometimes by tweaking some of the defines
148 below. It has been tested most extensively on Solaris and
149 Linux. It is also reported to work on WIN32 platforms.
150 People have also reported adapting this malloc for use in
151 stand-alone embedded systems.
152
153 The implementation is in straight, hand-tuned ANSI C. Among other
154 consequences, it uses a lot of macros. Because of this, to be at
155 all usable, this code should be compiled using an optimizing compiler
156 (for example gcc -O2) that can simplify expressions and control
157 paths.
158
159 __STD_C (default: derived from C compiler defines)
160 Nonzero if using ANSI-standard C compiler, a C++ compiler, or
161 a C compiler sufficiently close to ANSI to get away with it.
162 DEBUG (default: NOT defined)
163 Define to enable debugging. Adds fairly extensive assertion-based
164 checking to help track down memory errors, but noticeably slows down
165 execution.
166 SEPARATE_OBJECTS (default: NOT defined)
167 Define this to compile into separate .o files. You must then
168 compile malloc.c several times, defining a DEFINE_* macro each
169 time. The list of DEFINE_* macros appears below.
170 MALLOC_LOCK (default: NOT defined)
171 MALLOC_UNLOCK (default: NOT defined)
172 Define these to C expressions which are run to lock and unlock
173 the malloc data structures. Calls may be nested; that is,
174 MALLOC_LOCK may be called more than once before the corresponding
175 MALLOC_UNLOCK calls. MALLOC_LOCK must avoid waiting for a lock
176 that it already holds.
177 MALLOC_ALIGNMENT (default: NOT defined)
178 Define this to 16 if you need 16 byte alignment instead of 8 byte alignment
179 which is the normal default.
180 REALLOC_ZERO_BYTES_FREES (default: NOT defined)
181 Define this if you think that realloc(p, 0) should be equivalent
182 to free(p). Otherwise, since malloc returns a unique pointer for
183 malloc(0), so does realloc(p, 0).
184 HAVE_MEMCPY (default: defined)
185 Define if you are not otherwise using ANSI STD C, but still
186 have memcpy and memset in your C library and want to use them.
187 Otherwise, simple internal versions are supplied.
188 USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)
189 Define as 1 if you want the C library versions of memset and
190 memcpy called in realloc and calloc (otherwise macro versions are used).
191 At least on some platforms, the simple macro versions usually
192 outperform libc versions.
193 HAVE_MMAP (default: defined as 1)
194 Define to non-zero to optionally make malloc() use mmap() to
195 allocate very large blocks.
196 HAVE_MREMAP (default: defined as 0 unless Linux libc set)
197 Define to non-zero to optionally make realloc() use mremap() to
198 reallocate very large blocks.
199 malloc_getpagesize (default: derived from system #includes)
200 Either a constant or routine call returning the system page size.
201 HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)
202 Optionally define if you are on a system with a /usr/include/malloc.h
203 that declares struct mallinfo. It is not at all necessary to
204 define this even if you do, but will ensure consistency.
205 INTERNAL_SIZE_T (default: size_t)
206 Define to a 32-bit type (probably `unsigned int') if you are on a
207 64-bit machine, yet do not want or need to allow malloc requests of
208 greater than 2^31 to be handled. This saves space, especially for
209 very small chunks.
210 INTERNAL_LINUX_C_LIB (default: NOT defined)
211 Defined only when compiled as part of Linux libc.
212 Also note that there is some odd internal name-mangling via defines
213 (for example, internally, `malloc' is named `mALLOc') needed
214 when compiling in this case. These look funny but don't otherwise
215 affect anything.
216 _LIBC (default: NOT defined)
217 Defined only when compiled as part of the Cygnus newlib
218 distribution.
219 WIN32 (default: undefined)
220 Define this on MS win (95, nt) platforms to compile in sbrk emulation.
221 LACKS_UNISTD_H (default: undefined)
222 Define this if your system does not have a <unistd.h>.
223 MORECORE (default: sbrk)
224 The name of the routine to call to obtain more memory from the system.
225 MORECORE_FAILURE (default: -1)
226 The value returned upon failure of MORECORE.
227 MORECORE_CLEARS (default 1)
228 True (1) if the routine mapped to MORECORE zeroes out memory (which
229 holds for sbrk).
230 DEFAULT_TRIM_THRESHOLD
231 DEFAULT_TOP_PAD
232 DEFAULT_MMAP_THRESHOLD
233 DEFAULT_MMAP_MAX
234 Default values of tunable parameters (described in detail below)
235 controlling interaction with host system routines (sbrk, mmap, etc).
236 These values may also be changed dynamically via mallopt(). The
237 preset defaults are those that give best performance for typical
238 programs/systems.
239
240
241 */
242
243
244
245
246 /* Preliminaries */
247
248 #define _DEFAULT_SOURCE
249 #ifndef __STD_C
250 #ifdef __STDC__
251 #define __STD_C 1
252 #else
253 #if __cplusplus
254 #define __STD_C 1
255 #else
256 #define __STD_C 0
257 #endif /*__cplusplus*/
258 #endif /*__STDC__*/
259 #endif /*__STD_C*/
260
261 #ifndef Void_t
262 #if __STD_C
263 #define Void_t void
264 #else
265 #define Void_t char
266 #endif
267 #endif /*Void_t*/
268
269 #if __STD_C
270 #include <stddef.h> /* for size_t */
271 #else
272 #include <sys/types.h>
273 #endif
274
275 #ifdef __cplusplus
276 extern "C" {
277 #endif
278
279 #include <stdio.h> /* needed for malloc_stats */
280 #include <limits.h> /* needed for overflow checks */
281 #include <errno.h> /* needed to set errno to ENOMEM */
282
283 #ifdef WIN32
284 #define WIN32_LEAN_AND_MEAN
285 #include <windows.h>
286 #endif
287
288 /*
289 Compile-time options
290 */
291
292
293 /*
294
295 Special defines for Cygnus newlib distribution.
296
297 */
298
299 #ifdef _LIBC
300
301 #include <sys/config.h>
302 #include <sys/lock.h>
303
304 #define POINTER_UINT unsigned _POINTER_INT
305 #define SEPARATE_OBJECTS
306 #define HAVE_MMAP 0
307 #define MORECORE(size) sbrk((size))
308 #define MORECORE_CLEARS 0
309 #define MALLOC_LOCK __LIBC_LOCK()
310 #define MALLOC_UNLOCK __LIBC_UNLOCK()
311
312 #ifdef __CYGWIN__
313 # undef _WIN32
314 # undef WIN32
315 #endif
316
317 #ifndef _WIN32
318 #ifdef SMALL_MEMORY
319 #define malloc_getpagesize (128)
320 #else
321 #define malloc_getpagesize (4096)
322 #endif
323 #endif
324
325 #if __STD_C
326 extern void __malloc_lock(void);
327 extern void __malloc_unlock(void);
328 #else
329 extern void __malloc_lock();
330 extern void __malloc_unlock();
331 #endif
332
333 #else /* ! _LIBC */
334
335 #define POINTER_UINT unsigned long
336
337 #endif /* ! _LIBC */
338
339 /*
340 Debugging:
341
342 Because freed chunks may be overwritten with link fields, this
343 malloc will often die when freed memory is overwritten by user
344 programs. This can be very effective (albeit in an annoying way)
345 in helping track down dangling pointers.
346
347 If you compile with -DDEBUG, a number of assertion checks are
348 enabled that will catch more memory errors. You probably won't be
349 able to make much sense of the actual assertion errors, but they
350 should help you locate incorrectly overwritten memory. The
351 checking is fairly extensive, and will slow down execution
352 noticeably. Calling malloc_stats or mallinfo with DEBUG set will
353 attempt to check every non-mmapped allocated and free chunk in the
354 course of computing the summmaries. (By nature, mmapped regions
355 cannot be checked very much automatically.)
356
357 Setting DEBUG may also be helpful if you are trying to modify
358 this code. The assertions in the check routines spell out in more
359 detail the assumptions and invariants underlying the algorithms.
360
361 */
362
363 #if DEBUG
364 #include <assert.h>
365 #else
366 #define assert(x) ((void)0)
367 #endif
368
369
370 /*
371 SEPARATE_OBJECTS should be defined if you want each function to go
372 into a separate .o file. You must then compile malloc.c once per
373 function, defining the appropriate DEFINE_ macro. See below for the
374 list of macros.
375 */
376
377 #ifndef SEPARATE_OBJECTS
378 #define DEFINE_MALLOC
379 #define DEFINE_FREE
380 #define DEFINE_REALLOC
381 #define DEFINE_CALLOC
382 #define DEFINE_CFREE
383 #define DEFINE_MEMALIGN
384 #define DEFINE_VALLOC
385 #define DEFINE_PVALLOC
386 #define DEFINE_MALLINFO
387 #define DEFINE_MALLOC_STATS
388 #define DEFINE_MALLOC_USABLE_SIZE
389 #define DEFINE_MALLOPT
390
391 #define STATIC static
392 #else
393 #define STATIC
394 #endif
395
396 /*
397 INTERNAL_SIZE_T is the word-size used for internal bookkeeping
398 of chunk sizes. On a 64-bit machine, you can reduce malloc
399 overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'
400 at the expense of not being able to handle requests greater than
401 2^31. This limitation is hardly ever a concern; you are encouraged
402 to set this. However, the default version is the same as size_t.
403 Since the implementation relies on __builtin_mul_overflow, defining
404 a custom INTERNAL_SIZE_T on machines/compilers without
405 __builtin_mul_overflow is not permitted.
406 */
407
408 #ifndef INTERNAL_SIZE_T
409 #define INTERNAL_SIZE_T size_t
410 #elif !defined(_HAVE_BUILTIN_MUL_OVERFLOW)
411 #error Compiler does not support __builtin_mul_overflow, hence INTERNAL_SIZE_T cannot be set
412 #endif
413
414 /*
415 Following is needed on implementations whereby long > size_t.
416 The problem is caused because the code performs subtractions of
417 size_t values and stores the result in long values. In the case
418 where long > size_t and the first value is actually less than
419 the second value, the resultant value is positive. For example,
420 (long)(x - y) where x = 0 and y is 1 ends up being 0x00000000FFFFFFFF
421 which is 2*31 - 1 instead of 0xFFFFFFFFFFFFFFFF. This is due to the
422 fact that assignment from unsigned to signed won't sign extend.
423 */
424
425 #define long_sub_size_t(x, y) \
426 (sizeof (long) > sizeof (INTERNAL_SIZE_T) && x < y \
427 ? -(long) (y - x) \
428 : (long) (x - y))
429
430 /*
431 REALLOC_ZERO_BYTES_FREES should be set if a call to
432 realloc with zero bytes should be the same as a call to free.
433 Some people think it should. Otherwise, since this malloc
434 returns a unique pointer for malloc(0), so does realloc(p, 0).
435 */
436
437
438 /* #define REALLOC_ZERO_BYTES_FREES */
439
440
441 /*
442 WIN32 causes an emulation of sbrk to be compiled in
443 mmap-based options are not currently supported in WIN32.
444 */
445
446 /* #define WIN32 */
447 #ifdef WIN32
448 #define MORECORE wsbrk
449 #define HAVE_MMAP 0
450 #endif
451
452
453 /*
454 HAVE_MEMCPY should be defined if you are not otherwise using
455 ANSI STD C, but still have memcpy and memset in your C library
456 and want to use them in calloc and realloc. Otherwise simple
457 macro versions are defined here.
458
459 USE_MEMCPY should be defined as 1 if you actually want to
460 have memset and memcpy called. People report that the macro
461 versions are often enough faster than libc versions on many
462 systems that it is better to use them.
463
464 */
465
466 #define HAVE_MEMCPY
467
468 /* Although the original macro is called USE_MEMCPY, newlib actually
469 uses memmove to handle cases whereby a platform's memcpy implementation
470 copies backwards and thus destructive overlap may occur in realloc
471 whereby we are reclaiming free memory prior to the old allocation. */
472 #ifndef USE_MEMCPY
473 #ifdef HAVE_MEMCPY
474 #define USE_MEMCPY 1
475 #else
476 #define USE_MEMCPY 0
477 #endif
478 #endif
479
480 #if (__STD_C || defined(HAVE_MEMCPY))
481
482 #if __STD_C
483 void* memset(void*, int, size_t);
484 void* memcpy(void*, const void*, size_t);
485 void* memmove(void*, const void*, size_t);
486 #else
487 Void_t* memset();
488 Void_t* memcpy();
489 Void_t* memmove();
490 #endif
491 #endif
492
493 #if USE_MEMCPY
494
495 /* The following macros are only invoked with (2n+1)-multiples of
496 INTERNAL_SIZE_T units, with a positive integer n. This is exploited
497 for fast inline execution when n is small. */
498
499 #define MALLOC_ZERO(charp, nbytes) \
500 do { \
501 INTERNAL_SIZE_T mzsz = (nbytes); \
502 if(mzsz <= 9*sizeof(mzsz)) { \
503 INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \
504 if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \
505 *mz++ = 0; \
506 if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \
507 *mz++ = 0; \
508 if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \
509 *mz++ = 0; }}} \
510 *mz++ = 0; \
511 *mz++ = 0; \
512 *mz = 0; \
513 } else memset((charp), 0, mzsz); \
514 } while(0)
515
516 #define MALLOC_COPY(dest,src,nbytes) \
517 do { \
518 INTERNAL_SIZE_T mcsz = (nbytes); \
519 if(mcsz <= 9*sizeof(mcsz)) { \
520 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \
521 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \
522 if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
523 *mcdst++ = *mcsrc++; \
524 if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
525 *mcdst++ = *mcsrc++; \
526 if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
527 *mcdst++ = *mcsrc++; }}} \
528 *mcdst++ = *mcsrc++; \
529 *mcdst++ = *mcsrc++; \
530 *mcdst = *mcsrc ; \
531 } else memmove(dest, src, mcsz); \
532 } while(0)
533
534 #else /* !USE_MEMCPY */
535
536 /* Use Duff's device for good zeroing/copying performance. */
537
538 #define MALLOC_ZERO(charp, nbytes) \
539 do { \
540 INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \
541 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
542 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
543 switch (mctmp) { \
544 case 0: for(;;) { *mzp++ = 0; \
545 case 7: *mzp++ = 0; \
546 case 6: *mzp++ = 0; \
547 case 5: *mzp++ = 0; \
548 case 4: *mzp++ = 0; \
549 case 3: *mzp++ = 0; \
550 case 2: *mzp++ = 0; \
551 case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \
552 } \
553 } while(0)
554
555 #define MALLOC_COPY(dest,src,nbytes) \
556 do { \
557 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \
558 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \
559 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
560 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
561 switch (mctmp) { \
562 case 0: for(;;) { *mcdst++ = *mcsrc++; \
563 case 7: *mcdst++ = *mcsrc++; \
564 case 6: *mcdst++ = *mcsrc++; \
565 case 5: *mcdst++ = *mcsrc++; \
566 case 4: *mcdst++ = *mcsrc++; \
567 case 3: *mcdst++ = *mcsrc++; \
568 case 2: *mcdst++ = *mcsrc++; \
569 case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \
570 } \
571 } while(0)
572
573 #endif
574
575
576 /*
577 Define HAVE_MMAP to optionally make malloc() use mmap() to
578 allocate very large blocks. These will be returned to the
579 operating system immediately after a free().
580 */
581
582 #ifndef HAVE_MMAP
583 #define HAVE_MMAP 1
584 #endif
585
586 /*
587 Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
588 large blocks. This is currently only possible on Linux with
589 kernel versions newer than 1.3.77.
590 */
591
592 #ifndef HAVE_MREMAP
593 #ifdef INTERNAL_LINUX_C_LIB
594 #define HAVE_MREMAP 1
595 #else
596 #define HAVE_MREMAP 0
597 #endif
598 #endif
599
600 #if HAVE_MMAP
601
602 #include <unistd.h>
603 #include <fcntl.h>
604 #include <sys/mman.h>
605
606 #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
607 #define MAP_ANONYMOUS MAP_ANON
608 #endif
609
610 #endif /* HAVE_MMAP */
611
612 /*
613 Access to system page size. To the extent possible, this malloc
614 manages memory from the system in page-size units.
615
616 The following mechanics for getpagesize were adapted from
617 bsd/gnu getpagesize.h
618 */
619
620 #ifndef LACKS_UNISTD_H
621 # include <unistd.h>
622 #endif
623
624 #ifndef malloc_getpagesize
625 # ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
626 # ifndef _SC_PAGE_SIZE
627 # define _SC_PAGE_SIZE _SC_PAGESIZE
628 # endif
629 # endif
630 # ifdef _SC_PAGE_SIZE
631 # define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
632 # else
633 # if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
634 extern size_t getpagesize();
635 # define malloc_getpagesize getpagesize()
636 # else
637 # include <sys/param.h>
638 # ifdef EXEC_PAGESIZE
639 # define malloc_getpagesize EXEC_PAGESIZE
640 # else
641 # ifdef NBPG
642 # ifndef CLSIZE
643 # define malloc_getpagesize NBPG
644 # else
645 # define malloc_getpagesize (NBPG * CLSIZE)
646 # endif
647 # else
648 # ifdef NBPC
649 # define malloc_getpagesize NBPC
650 # else
651 # ifdef PAGESIZE
652 # define malloc_getpagesize PAGESIZE
653 # else
654 # define malloc_getpagesize (4096) /* just guess */
655 # endif
656 # endif
657 # endif
658 # endif
659 # endif
660 # endif
661 #endif
662
663
664
665 /*
666
667 This version of malloc supports the standard SVID/XPG mallinfo
668 routine that returns a struct containing the same kind of
669 information you can get from malloc_stats. It should work on
670 any SVID/XPG compliant system that has a /usr/include/malloc.h
671 defining struct mallinfo. (If you'd like to install such a thing
672 yourself, cut out the preliminary declarations as described above
673 and below and save them in a malloc.h file. But there's no
674 compelling reason to bother to do this.)
675
676 The main declaration needed is the mallinfo struct that is returned
677 (by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
678 bunch of fields, most of which are not even meaningful in this
679 version of malloc. Some of these fields are are instead filled by
680 mallinfo() with other numbers that might possibly be of interest.
681
682 HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
683 /usr/include/malloc.h file that includes a declaration of struct
684 mallinfo. If so, it is included; else an SVID2/XPG2 compliant
685 version is declared below. These must be precisely the same for
686 mallinfo() to work.
687
688 */
689
690 /* #define HAVE_USR_INCLUDE_MALLOC_H */
691
692 #if HAVE_USR_INCLUDE_MALLOC_H
693 #include "/usr/include/malloc.h"
694 #else
695
696 /* SVID2/XPG mallinfo structure */
697
698 struct mallinfo {
699 int arena; /* total space allocated from system */
700 int ordblks; /* number of non-inuse chunks */
701 int smblks; /* unused -- always zero */
702 int hblks; /* number of mmapped regions */
703 int hblkhd; /* total space in mmapped regions */
704 int usmblks; /* unused -- always zero */
705 int fsmblks; /* unused -- always zero */
706 int uordblks; /* total allocated space */
707 int fordblks; /* total non-inuse space */
708 int keepcost; /* top-most, releasable (via malloc_trim) space */
709 };
710
711 /* SVID2/XPG mallopt options */
712
713 #define M_MXFAST 1 /* UNUSED in this malloc */
714 #define M_NLBLKS 2 /* UNUSED in this malloc */
715 #define M_GRAIN 3 /* UNUSED in this malloc */
716 #define M_KEEP 4 /* UNUSED in this malloc */
717
718 #endif
719
720 /* mallopt options that actually do something */
721
722 #define M_TRIM_THRESHOLD -1
723 #define M_TOP_PAD -2
724 #define M_MMAP_THRESHOLD -3
725 #define M_MMAP_MAX -4
726
727
728
729 #ifndef DEFAULT_TRIM_THRESHOLD
730 #define DEFAULT_TRIM_THRESHOLD (128L * 1024L)
731 #endif
732
733 /*
734 M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
735 to keep before releasing via malloc_trim in free().
736
737 Automatic trimming is mainly useful in long-lived programs.
738 Because trimming via sbrk can be slow on some systems, and can
739 sometimes be wasteful (in cases where programs immediately
740 afterward allocate more large chunks) the value should be high
741 enough so that your overall system performance would improve by
742 releasing.
743
744 The trim threshold and the mmap control parameters (see below)
745 can be traded off with one another. Trimming and mmapping are
746 two different ways of releasing unused memory back to the
747 system. Between these two, it is often possible to keep
748 system-level demands of a long-lived program down to a bare
749 minimum. For example, in one test suite of sessions measuring
750 the XF86 X server on Linux, using a trim threshold of 128K and a
751 mmap threshold of 192K led to near-minimal long term resource
752 consumption.
753
754 If you are using this malloc in a long-lived program, it should
755 pay to experiment with these values. As a rough guide, you
756 might set to a value close to the average size of a process
757 (program) running on your system. Releasing this much memory
758 would allow such a process to run in memory. Generally, it's
759 worth it to tune for trimming rather tham memory mapping when a
760 program undergoes phases where several large chunks are
761 allocated and released in ways that can reuse each other's
762 storage, perhaps mixed with phases where there are no such
763 chunks at all. And in well-behaved long-lived programs,
764 controlling release of large blocks via trimming versus mapping
765 is usually faster.
766
767 However, in most programs, these parameters serve mainly as
768 protection against the system-level effects of carrying around
769 massive amounts of unneeded memory. Since frequent calls to
770 sbrk, mmap, and munmap otherwise degrade performance, the default
771 parameters are set to relatively high values that serve only as
772 safeguards.
773
774 The default trim value is high enough to cause trimming only in
775 fairly extreme (by current memory consumption standards) cases.
776 It must be greater than page size to have any useful effect. To
777 disable trimming completely, you can set to (unsigned long)(-1);
778
779
780 */
781
782
783 #ifndef DEFAULT_TOP_PAD
784 #define DEFAULT_TOP_PAD (0)
785 #endif
786
787 /*
788 M_TOP_PAD is the amount of extra `padding' space to allocate or
789 retain whenever sbrk is called. It is used in two ways internally:
790
791 * When sbrk is called to extend the top of the arena to satisfy
792 a new malloc request, this much padding is added to the sbrk
793 request.
794
795 * When malloc_trim is called automatically from free(),
796 it is used as the `pad' argument.
797
798 In both cases, the actual amount of padding is rounded
799 so that the end of the arena is always a system page boundary.
800
801 The main reason for using padding is to avoid calling sbrk so
802 often. Having even a small pad greatly reduces the likelihood
803 that nearly every malloc request during program start-up (or
804 after trimming) will invoke sbrk, which needlessly wastes
805 time.
806
807 Automatic rounding-up to page-size units is normally sufficient
808 to avoid measurable overhead, so the default is 0. However, in
809 systems where sbrk is relatively slow, it can pay to increase
810 this value, at the expense of carrying around more memory than
811 the program needs.
812
813 */
814
815
816 #ifndef DEFAULT_MMAP_THRESHOLD
817 #define DEFAULT_MMAP_THRESHOLD (128 * 1024)
818 #endif
819
820 /*
821
822 M_MMAP_THRESHOLD is the request size threshold for using mmap()
823 to service a request. Requests of at least this size that cannot
824 be allocated using already-existing space will be serviced via mmap.
825 (If enough normal freed space already exists it is used instead.)
826
827 Using mmap segregates relatively large chunks of memory so that
828 they can be individually obtained and released from the host
829 system. A request serviced through mmap is never reused by any
830 other request (at least not directly; the system may just so
831 happen to remap successive requests to the same locations).
832
833 Segregating space in this way has the benefit that mmapped space
834 can ALWAYS be individually released back to the system, which
835 helps keep the system level memory demands of a long-lived
836 program low. Mapped memory can never become `locked' between
837 other chunks, as can happen with normally allocated chunks, which
838 menas that even trimming via malloc_trim would not release them.
839
840 However, it has the disadvantages that:
841
842 1. The space cannot be reclaimed, consolidated, and then
843 used to service later requests, as happens with normal chunks.
844 2. It can lead to more wastage because of mmap page alignment
845 requirements
846 3. It causes malloc performance to be more dependent on host
847 system memory management support routines which may vary in
848 implementation quality and may impose arbitrary
849 limitations. Generally, servicing a request via normal
850 malloc steps is faster than going through a system's mmap.
851
852 All together, these considerations should lead you to use mmap
853 only for relatively large requests.
854
855
856 */
857
858
859
860 #ifndef DEFAULT_MMAP_MAX
861 #if HAVE_MMAP
862 #define DEFAULT_MMAP_MAX (64)
863 #else
864 #define DEFAULT_MMAP_MAX (0)
865 #endif
866 #endif
867
868 /*
869 M_MMAP_MAX is the maximum number of requests to simultaneously
870 service using mmap. This parameter exists because:
871
872 1. Some systems have a limited number of internal tables for
873 use by mmap.
874 2. In most systems, overreliance on mmap can degrade overall
875 performance.
876 3. If a program allocates many large regions, it is probably
877 better off using normal sbrk-based allocation routines that
878 can reclaim and reallocate normal heap memory. Using a
879 small value allows transition into this mode after the
880 first few allocations.
881
882 Setting to 0 disables all use of mmap. If HAVE_MMAP is not set,
883 the default value is 0, and attempts to set it to non-zero values
884 in mallopt will fail.
885 */
886
887
888
889
890 /*
891
892 Special defines for linux libc
893
894 Except when compiled using these special defines for Linux libc
895 using weak aliases, this malloc is NOT designed to work in
896 multithreaded applications. No semaphores or other concurrency
897 control are provided to ensure that multiple malloc or free calls
898 don't run at the same time, which could be disasterous. A single
899 semaphore could be used across malloc, realloc, and free (which is
900 essentially the effect of the linux weak alias approach). It would
901 be hard to obtain finer granularity.
902
903 */
904
905
906 #ifdef INTERNAL_LINUX_C_LIB
907
908 #if __STD_C
909
910 Void_t * __default_morecore_init (ptrdiff_t);
911 Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init;
912
913 #else
914
915 Void_t * __default_morecore_init ();
916 Void_t *(*__morecore)() = __default_morecore_init;
917
918 #endif
919
920 #define MORECORE (*__morecore)
921 #define MORECORE_FAILURE 0
922 #define MORECORE_CLEARS 1
923
924 #else /* INTERNAL_LINUX_C_LIB */
925
926 #ifndef _LIBC
927 #if __STD_C
928 extern Void_t* sbrk(ptrdiff_t);
929 #else
930 extern Void_t* sbrk();
931 #endif
932 #endif
933
934 #ifndef MORECORE
935 #define MORECORE sbrk
936 #endif
937
938 #ifndef MORECORE_FAILURE
939 #define MORECORE_FAILURE -1
940 #endif
941
942 #ifndef MORECORE_CLEARS
943 #define MORECORE_CLEARS 1
944 #endif
945
946 #endif /* INTERNAL_LINUX_C_LIB */
947
948 #if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__)
949
950 #define cALLOc __libc_calloc
951 #define fREe __libc_free
952 #define mALLOc __libc_malloc
953 #define mEMALIGn __libc_memalign
954 #define rEALLOc __libc_realloc
955 #define vALLOc __libc_valloc
956 #define pvALLOc __libc_pvalloc
957 #define mALLINFo __libc_mallinfo
958 #define mALLOPt __libc_mallopt
959
960 #pragma weak calloc = __libc_calloc
961 #pragma weak free = __libc_free
962 #pragma weak cfree = __libc_free
963 #pragma weak malloc = __libc_malloc
964 #pragma weak memalign = __libc_memalign
965 #pragma weak realloc = __libc_realloc
966 #pragma weak valloc = __libc_valloc
967 #pragma weak pvalloc = __libc_pvalloc
968 #pragma weak mallinfo = __libc_mallinfo
969 #pragma weak mallopt = __libc_mallopt
970
971 #else
972
973 #define cALLOc calloc
974 #define fREe free
975 #define mALLOc malloc
976 #define mEMALIGn memalign
977 #define rEALLOc realloc
978 #define vALLOc valloc
979 #define pvALLOc pvalloc
980 #define mALLINFo mallinfo
981 #define mALLOPt mallopt
982
983 #ifdef _LIBC
984
985 #define malloc_stats malloc_stats
986 #define malloc_trim malloc_trim
987 #define malloc_usable_size malloc_usable_size
988
989 #define malloc_update_mallinfo __malloc_update_mallinfo
990
991 #define malloc_av_ __malloc_av_
992 #define malloc_current_mallinfo __malloc_current_mallinfo
993 #define malloc_max_sbrked_mem __malloc_max_sbrked_mem
994 #define malloc_max_total_mem __malloc_max_total_mem
995 #define malloc_sbrk_base __malloc_sbrk_base
996 #define malloc_top_pad __malloc_top_pad
997 #define malloc_trim_threshold __malloc_trim_threshold
998
999 #endif /* ! _LIBC */
1000 #endif
1001
1002 /* Public routines */
1003
1004 #if __STD_C
1005
1006 Void_t* mALLOc(size_t);
1007 void fREe(Void_t*);
1008 Void_t* rEALLOc(Void_t*, size_t);
1009 Void_t* mEMALIGn(size_t, size_t);
1010 Void_t* vALLOc(size_t);
1011 Void_t* pvALLOc(size_t);
1012 Void_t* cALLOc(size_t, size_t);
1013 void cfree(Void_t*);
1014 int malloc_trim(size_t);
1015 size_t malloc_usable_size(Void_t*);
1016 void malloc_stats(void);
1017 int mALLOPt(int, int);
1018 struct mallinfo mALLINFo(void);
1019 #else
1020 Void_t* mALLOc();
1021 void fREe();
1022 Void_t* rEALLOc();
1023 Void_t* mEMALIGn();
1024 Void_t* vALLOc();
1025 Void_t* pvALLOc();
1026 Void_t* cALLOc();
1027 void cfree();
1028 int malloc_trim();
1029 size_t malloc_usable_size();
1030 void malloc_stats();
1031 int mALLOPt();
1032 struct mallinfo mALLINFo();
1033 #endif
1034
1035 /* Work around compiler optimizing away stores to 'size' field before
1036 * call to free.
1037 */
1038 #ifdef _HAVE_ALIAS_ATTRIBUTE
1039 extern __typeof(free) __malloc_free;
1040 #else
1041 #define __malloc_free(x) fREe(x)
1042 #endif
1043
1044 #ifdef __cplusplus
1045 }; /* end of extern "C" */
1046 #endif
1047
1048 /* ---------- To make a malloc.h, end cutting here ------------ */
1049
1050
1051 /*
1052 Emulation of sbrk for WIN32
1053 All code within the ifdef WIN32 is untested by me.
1054 */
1055
1056
1057 #ifdef WIN32
1058
1059 #define AlignPage(add) (((add) + (malloc_getpagesize-1)) & \
1060 ~(malloc_getpagesize-1))
1061
1062 /* resrve 64MB to insure large contiguous space */
1063 #define RESERVED_SIZE (1024*1024*64)
1064 #define NEXT_SIZE (2048*1024)
1065 #define TOP_MEMORY ((unsigned long)2*1024*1024*1024)
1066
1067 struct GmListElement;
1068 typedef struct GmListElement GmListElement;
1069
1070 struct GmListElement
1071 {
1072 GmListElement* next;
1073 void* base;
1074 };
1075
1076 static GmListElement* head = 0;
1077 static unsigned int gNextAddress = 0;
1078 static unsigned int gAddressBase = 0;
1079 static unsigned int gAllocatedSize = 0;
1080
1081 static
makeGmListElement(void * bas)1082 GmListElement* makeGmListElement (void* bas)
1083 {
1084 GmListElement* this;
1085 this = (GmListElement*)(void*)LocalAlloc (0, sizeof (GmListElement));
1086 ASSERT (this);
1087 if (this)
1088 {
1089 this->base = bas;
1090 this->next = head;
1091 head = this;
1092 }
1093 return this;
1094 }
1095
gcleanup(void)1096 void gcleanup (void)
1097 {
1098 BOOL rval;
1099 ASSERT ( (head == NULL) || (head->base == (void*)gAddressBase));
1100 if (gAddressBase && (gNextAddress - gAddressBase))
1101 {
1102 rval = VirtualFree ((void*)gAddressBase,
1103 gNextAddress - gAddressBase,
1104 MEM_DECOMMIT);
1105 ASSERT (rval);
1106 }
1107 while (head)
1108 {
1109 GmListElement* next = head->next;
1110 rval = VirtualFree (head->base, 0, MEM_RELEASE);
1111 ASSERT (rval);
1112 LocalFree (head);
1113 head = next;
1114 }
1115 }
1116
1117 static
findRegion(void * start_address,unsigned long size)1118 void* findRegion (void* start_address, unsigned long size)
1119 {
1120 MEMORY_BASIC_INFORMATION info;
1121 while ((unsigned long)start_address < TOP_MEMORY)
1122 {
1123 VirtualQuery (start_address, &info, sizeof (info));
1124 if (info.State != MEM_FREE)
1125 start_address = (char*)info.BaseAddress + info.RegionSize;
1126 else if (info.RegionSize >= size)
1127 return start_address;
1128 else
1129 start_address = (char*)info.BaseAddress + info.RegionSize;
1130 }
1131 return NULL;
1132
1133 }
1134
1135
wsbrk(long size)1136 void* wsbrk (long size)
1137 {
1138 void* tmp;
1139 if (size > 0)
1140 {
1141 if (gAddressBase == 0)
1142 {
1143 gAllocatedSize = max (RESERVED_SIZE, AlignPage (size));
1144 gNextAddress = gAddressBase =
1145 (unsigned int)VirtualAlloc (NULL, gAllocatedSize,
1146 MEM_RESERVE, PAGE_NOACCESS);
1147 } else if (AlignPage (gNextAddress + size) > (gAddressBase +
1148 gAllocatedSize))
1149 {
1150 long new_size = max (NEXT_SIZE, AlignPage (size));
1151 void* new_address = (void*)(gAddressBase+gAllocatedSize);
1152 do
1153 {
1154 new_address = findRegion (new_address, new_size);
1155
1156 if (new_address == 0)
1157 return (void*)-1;
1158
1159 gAddressBase = gNextAddress =
1160 (unsigned int)VirtualAlloc (new_address, new_size,
1161 MEM_RESERVE, PAGE_NOACCESS);
1162 // repeat in case of race condition
1163 // The region that we found has been snagged
1164 // by another thread
1165 }
1166 while (gAddressBase == 0);
1167
1168 ASSERT (new_address == (void*)gAddressBase);
1169
1170 gAllocatedSize = new_size;
1171
1172 if (!makeGmListElement ((void*)gAddressBase))
1173 return (void*)-1;
1174 }
1175 if ((size + gNextAddress) > AlignPage (gNextAddress))
1176 {
1177 void* res;
1178 res = VirtualAlloc ((void*)AlignPage (gNextAddress),
1179 (size + gNextAddress -
1180 AlignPage (gNextAddress)),
1181 MEM_COMMIT, PAGE_READWRITE);
1182 if (res == 0)
1183 return (void*)-1;
1184 }
1185 tmp = (void*)gNextAddress;
1186 gNextAddress = (unsigned int)tmp + size;
1187 return tmp;
1188 }
1189 else if (size < 0)
1190 {
1191 unsigned int alignedGoal = AlignPage (gNextAddress + size);
1192 /* Trim by releasing the virtual memory */
1193 if (alignedGoal >= gAddressBase)
1194 {
1195 VirtualFree ((void*)alignedGoal, gNextAddress - alignedGoal,
1196 MEM_DECOMMIT);
1197 gNextAddress = gNextAddress + size;
1198 return (void*)gNextAddress;
1199 }
1200 else
1201 {
1202 VirtualFree ((void*)gAddressBase, gNextAddress - gAddressBase,
1203 MEM_DECOMMIT);
1204 gNextAddress = gAddressBase;
1205 return (void*)-1;
1206 }
1207 }
1208 else
1209 {
1210 return (void*)gNextAddress;
1211 }
1212 }
1213
1214 #endif
1215
1216
1217
1218 /*
1219 Type declarations
1220 */
1221
1222
1223 struct malloc_chunk
1224 {
1225 INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */
1226 INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */
1227 struct malloc_chunk* fd; /* double links -- used only if free. */
1228 struct malloc_chunk* bk;
1229 };
1230
1231 typedef struct malloc_chunk* mchunkptr;
1232
1233 /*
1234
1235 malloc_chunk details:
1236
1237 (The following includes lightly edited explanations by Colin Plumb.)
1238
1239 Chunks of memory are maintained using a `boundary tag' method as
1240 described in e.g., Knuth or Standish. (See the paper by Paul
1241 Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
1242 survey of such techniques.) Sizes of free chunks are stored both
1243 in the front of each chunk and at the end. This makes
1244 consolidating fragmented chunks into bigger chunks very fast. The
1245 size fields also hold bits representing whether chunks are free or
1246 in use.
1247
1248 An allocated chunk looks like this:
1249
1250
1251 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1252 | Size of previous chunk, if allocated | |
1253 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1254 | Size of chunk, in bytes |P|
1255 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1256 | User data starts here... .
1257 . .
1258 . (malloc_usable_space() bytes) .
1259 . |
1260 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1261 | Size of chunk |
1262 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1263
1264
1265 Where "chunk" is the front of the chunk for the purpose of most of
1266 the malloc code, but "mem" is the pointer that is returned to the
1267 user. "Nextchunk" is the beginning of the next contiguous chunk.
1268
1269 Chunks always begin on even word boundries, so the mem portion
1270 (which is returned to the user) is also on an even word boundary, and
1271 thus double-word aligned.
1272
1273 Free chunks are stored in circular doubly-linked lists, and look like this:
1274
1275 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1276 | Size of previous chunk |
1277 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1278 `head:' | Size of chunk, in bytes |P|
1279 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1280 | Forward pointer to next chunk in list |
1281 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1282 | Back pointer to previous chunk in list |
1283 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1284 | Unused space (may be 0 bytes long) .
1285 . .
1286 . |
1287 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1288 `foot:' | Size of chunk, in bytes |
1289 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1290
1291 The P (PREV_INUSE) bit, stored in the unused low-order bit of the
1292 chunk size (which is always a multiple of two words), is an in-use
1293 bit for the *previous* chunk. If that bit is *clear*, then the
1294 word before the current chunk size contains the previous chunk
1295 size, and can be used to find the front of the previous chunk.
1296 (The very first chunk allocated always has this bit set,
1297 preventing access to non-existent (or non-owned) memory.)
1298
1299 Note that the `foot' of the current chunk is actually represented
1300 as the prev_size of the NEXT chunk. (This makes it easier to
1301 deal with alignments etc).
1302
1303 The two exceptions to all this are
1304
1305 1. The special chunk `top', which doesn't bother using the
1306 trailing size field since there is no
1307 next contiguous chunk that would have to index off it. (After
1308 initialization, `top' is forced to always exist. If it would
1309 become less than MINSIZE bytes long, it is replenished via
1310 malloc_extend_top.)
1311
1312 2. Chunks allocated via mmap, which have the second-lowest-order
1313 bit (IS_MMAPPED) set in their size fields. Because they are
1314 never merged or traversed from any other chunk, they have no
1315 foot size or inuse information.
1316
1317 Available chunks are kept in any of several places (all declared below):
1318
1319 * `av': An array of chunks serving as bin headers for consolidated
1320 chunks. Each bin is doubly linked. The bins are approximately
1321 proportionally (log) spaced. There are a lot of these bins
1322 (128). This may look excessive, but works very well in
1323 practice. All procedures maintain the invariant that no
1324 consolidated chunk physically borders another one. Chunks in
1325 bins are kept in size order, with ties going to the
1326 approximately least recently used chunk.
1327
1328 The chunks in each bin are maintained in decreasing sorted order by
1329 size. This is irrelevant for the small bins, which all contain
1330 the same-sized chunks, but facilitates best-fit allocation for
1331 larger chunks. (These lists are just sequential. Keeping them in
1332 order almost never requires enough traversal to warrant using
1333 fancier ordered data structures.) Chunks of the same size are
1334 linked with the most recently freed at the front, and allocations
1335 are taken from the back. This results in LRU or FIFO allocation
1336 order, which tends to give each chunk an equal opportunity to be
1337 consolidated with adjacent freed chunks, resulting in larger free
1338 chunks and less fragmentation.
1339
1340 * `top': The top-most available chunk (i.e., the one bordering the
1341 end of available memory) is treated specially. It is never
1342 included in any bin, is used only if no other chunk is
1343 available, and is released back to the system if it is very
1344 large (see M_TRIM_THRESHOLD).
1345
1346 * `last_remainder': A bin holding only the remainder of the
1347 most recently split (non-top) chunk. This bin is checked
1348 before other non-fitting chunks, so as to provide better
1349 locality for runs of sequentially allocated chunks.
1350
1351 * Implicitly, through the host system's memory mapping tables.
1352 If supported, requests greater than a threshold are usually
1353 serviced via calls to mmap, and then later released via munmap.
1354
1355 */
1356
1357
1358
1359
1360
1361
1362 /* sizes, alignments */
1363
1364 #define SIZE_SZ (sizeof(INTERNAL_SIZE_T))
1365 #ifndef MALLOC_ALIGNMENT
1366 #define MALLOC_ALIGN 8
1367 #define MALLOC_ALIGNMENT (SIZE_SZ < 4 ? 8 : (SIZE_SZ + SIZE_SZ))
1368 #else
1369 #define MALLOC_ALIGN MALLOC_ALIGNMENT
1370 #endif
1371 #define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1)
1372 #define MINSIZE (sizeof(struct malloc_chunk))
1373
1374 /* conversion from malloc headers to user pointers, and back */
1375
1376 #define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ))
1377 #define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))
1378
1379 /* pad request bytes into a usable size */
1380
1381 #define request2size(req) \
1382 (((unsigned long)((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \
1383 (unsigned long)(MINSIZE + MALLOC_ALIGN_MASK)) ? ((MINSIZE + MALLOC_ALIGN_MASK) & ~(MALLOC_ALIGN_MASK)) : \
1384 (((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) & ~(MALLOC_ALIGN_MASK)))
1385
1386 /* Check if m has acceptable alignment */
1387
1388 #define aligned_OK(m) (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0)
1389
1390
1391
1392
1393 /*
1394 Physical chunk operations
1395 */
1396
1397
1398 /* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
1399
1400 #define PREV_INUSE 0x1
1401
1402 /* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
1403
1404 #define IS_MMAPPED 0x2
1405
1406 /* Bits to mask off when extracting size */
1407
1408 #define SIZE_BITS (PREV_INUSE|IS_MMAPPED)
1409
1410
1411 /* Ptr to next physical malloc_chunk. */
1412
1413 #define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) ))
1414
1415 /* Ptr to previous physical malloc_chunk */
1416
1417 #define prev_chunk(p)\
1418 ((mchunkptr)( ((char*)(p)) - ((p)->prev_size) ))
1419
1420
1421 /* Treat space at ptr + offset as a chunk */
1422
1423 #define chunk_at_offset(p, s) ((mchunkptr)(((char*)(p)) + (s)))
1424
1425
1426
1427
1428 /*
1429 Dealing with use bits
1430 */
1431
1432 /* extract p's inuse bit */
1433
1434 #define inuse(p)\
1435 ((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE)
1436
1437 /* extract inuse bit of previous chunk */
1438
1439 #define prev_inuse(p) ((p)->size & PREV_INUSE)
1440
1441 /* check for mmap()'ed chunk */
1442
1443 #define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED)
1444
1445 /* set/clear chunk as in use without otherwise disturbing */
1446
1447 #define set_inuse(p)\
1448 ((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE
1449
1450 #define clear_inuse(p)\
1451 ((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE)
1452
1453 /* check/set/clear inuse bits in known places */
1454
1455 #define inuse_bit_at_offset(p, s)\
1456 (((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE)
1457
1458 #define set_inuse_bit_at_offset(p, s)\
1459 (((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE)
1460
1461 #define clear_inuse_bit_at_offset(p, s)\
1462 (((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE))
1463
1464
1465
1466
1467 /*
1468 Dealing with size fields
1469 */
1470
1471 /* Get size, ignoring use bits */
1472
1473 #define chunksize(p) ((p)->size & ~(SIZE_BITS))
1474
1475 /* Set size at head, without disturbing its use bit */
1476
1477 #define set_head_size(p, s) ((p)->size = (((p)->size & PREV_INUSE) | (s)))
1478
1479 /* Set size/use ignoring previous bits in header */
1480
1481 #define set_head(p, s) ((p)->size = (s))
1482
1483 /* Set size at footer (only when chunk is not in use) */
1484
1485 #define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_size = (s))
1486
1487
1488
1489
1490
1491 /*
1492 Bins
1493
1494 The bins, `av_' are an array of pairs of pointers serving as the
1495 heads of (initially empty) doubly-linked lists of chunks, laid out
1496 in a way so that each pair can be treated as if it were in a
1497 malloc_chunk. (This way, the fd/bk offsets for linking bin heads
1498 and chunks are the same).
1499
1500 Bins for sizes < 512 bytes contain chunks of all the same size, spaced
1501 8 bytes apart. Larger bins are approximately logarithmically
1502 spaced. (See the table below.) The `av_' array is never mentioned
1503 directly in the code, but instead via bin access macros.
1504
1505 Bin layout:
1506
1507 64 bins of size 8
1508 32 bins of size 64
1509 16 bins of size 512
1510 8 bins of size 4096
1511 4 bins of size 32768
1512 2 bins of size 262144
1513 1 bin of size what's left
1514
1515 There is actually a little bit of slop in the numbers in bin_index
1516 for the sake of speed. This makes no difference elsewhere.
1517
1518 The special chunks `top' and `last_remainder' get their own bins,
1519 (this is implemented via yet more trickery with the av_ array),
1520 although `top' is never properly linked to its bin since it is
1521 always handled specially.
1522
1523 */
1524
1525 #ifdef SEPARATE_OBJECTS
1526 #define av_ malloc_av_
1527 #endif
1528
1529 #define NAV 128 /* number of bins */
1530
1531 typedef struct malloc_chunk* mbinptr;
1532
1533 /* access macros */
1534
1535 #define bin_at(i) ((mbinptr)((char*)&(av_[2*(i) + 2]) - 2*SIZE_SZ))
1536 #define next_bin(b) ((mbinptr)((char*)(b) + 2 * sizeof(mbinptr)))
1537 #define prev_bin(b) ((mbinptr)((char*)(b) - 2 * sizeof(mbinptr)))
1538
1539 /*
1540 The first 2 bins are never indexed. The corresponding av_ cells are instead
1541 used for bookkeeping. This is not to save space, but to simplify
1542 indexing, maintain locality, and avoid some initialization tests.
1543 */
1544
1545 #define top (bin_at(0)->fd) /* The topmost chunk */
1546 #define last_remainder (bin_at(1)) /* remainder from last split */
1547
1548
1549 /*
1550 Because top initially points to its own bin with initial
1551 zero size, thus forcing extension on the first malloc request,
1552 we avoid having any special code in malloc to check whether
1553 it even exists yet. But we still need to in malloc_extend_top.
1554 */
1555
1556 #define initial_top ((mchunkptr)(bin_at(0)))
1557
1558 /* Helper macro to initialize bins */
1559
1560 #define IAV(i) bin_at(i), bin_at(i)
1561
1562 #ifdef DEFINE_MALLOC
1563 STATIC mbinptr av_[NAV * 2 + 2] = {
1564 0, 0,
1565 IAV(0), IAV(1), IAV(2), IAV(3), IAV(4), IAV(5), IAV(6), IAV(7),
1566 IAV(8), IAV(9), IAV(10), IAV(11), IAV(12), IAV(13), IAV(14), IAV(15),
1567 IAV(16), IAV(17), IAV(18), IAV(19), IAV(20), IAV(21), IAV(22), IAV(23),
1568 IAV(24), IAV(25), IAV(26), IAV(27), IAV(28), IAV(29), IAV(30), IAV(31),
1569 IAV(32), IAV(33), IAV(34), IAV(35), IAV(36), IAV(37), IAV(38), IAV(39),
1570 IAV(40), IAV(41), IAV(42), IAV(43), IAV(44), IAV(45), IAV(46), IAV(47),
1571 IAV(48), IAV(49), IAV(50), IAV(51), IAV(52), IAV(53), IAV(54), IAV(55),
1572 IAV(56), IAV(57), IAV(58), IAV(59), IAV(60), IAV(61), IAV(62), IAV(63),
1573 IAV(64), IAV(65), IAV(66), IAV(67), IAV(68), IAV(69), IAV(70), IAV(71),
1574 IAV(72), IAV(73), IAV(74), IAV(75), IAV(76), IAV(77), IAV(78), IAV(79),
1575 IAV(80), IAV(81), IAV(82), IAV(83), IAV(84), IAV(85), IAV(86), IAV(87),
1576 IAV(88), IAV(89), IAV(90), IAV(91), IAV(92), IAV(93), IAV(94), IAV(95),
1577 IAV(96), IAV(97), IAV(98), IAV(99), IAV(100), IAV(101), IAV(102), IAV(103),
1578 IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111),
1579 IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119),
1580 IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127)
1581 };
1582 #else
1583 extern mbinptr av_[NAV * 2 + 2];
1584 #endif
1585
1586
1587
1588 /* field-extraction macros */
1589
1590 #define first(b) ((b)->fd)
1591 #define last(b) ((b)->bk)
1592
1593 /*
1594 Indexing into bins
1595 */
1596
1597 #define bin_index(sz) \
1598 (((((unsigned long)(sz)) >> 9) == 0) ? (((unsigned long)(sz)) >> 3): \
1599 ((((unsigned long)(sz)) >> 9) <= 4) ? 56 + (((unsigned long)(sz)) >> 6): \
1600 ((((unsigned long)(sz)) >> 9) <= 20) ? 91 + (((unsigned long)(sz)) >> 9): \
1601 ((((unsigned long)(sz)) >> 9) <= 84) ? 110 + (((unsigned long)(sz)) >> 12): \
1602 ((((unsigned long)(sz)) >> 9) <= 340) ? 119 + (((unsigned long)(sz)) >> 15): \
1603 ((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18): \
1604 126)
1605 /*
1606 bins for chunks < 512 are all spaced SMALLBIN_WIDTH bytes apart, and hold
1607 identically sized chunks. This is exploited in malloc.
1608 */
1609
1610 #define MAX_SMALLBIN_SIZE 512
1611 #define SMALLBIN_WIDTH 8
1612 #define SMALLBIN_WIDTH_BITS 3
1613 #define MAX_SMALLBIN (MAX_SMALLBIN_SIZE / SMALLBIN_WIDTH) - 1
1614
1615 #define smallbin_index(sz) (((unsigned long)(sz)) >> SMALLBIN_WIDTH_BITS)
1616
1617 /*
1618 Requests are `small' if both the corresponding and the next bin are small
1619 */
1620
1621 #define is_small_request(nb) (nb < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH)
1622
1623
1624
1625 /*
1626 To help compensate for the large number of bins, a one-level index
1627 structure is used for bin-by-bin searching. `binblocks' is a
1628 one-word bitvector recording whether groups of BINBLOCKWIDTH bins
1629 have any (possibly) non-empty bins, so they can be skipped over
1630 all at once during during traversals. The bits are NOT always
1631 cleared as soon as all bins in a block are empty, but instead only
1632 when all are noticed to be empty during traversal in malloc.
1633 */
1634
1635 #define BINBLOCKWIDTH 4 /* bins per block */
1636
1637 #define binblocks (bin_at(0)->size) /* bitvector of nonempty blocks */
1638
1639 /* bin<->block macros */
1640
1641 #define idx2binblock(ix) ((unsigned long)1 << (ix / BINBLOCKWIDTH))
1642 #define mark_binblock(ii) (binblocks |= idx2binblock(ii))
1643 #define clear_binblock(ii) (binblocks &= ~(idx2binblock(ii)))
1644
1645
1646
1647
1648
1649 /* Other static bookkeeping data */
1650
1651 #ifdef SEPARATE_OBJECTS
1652 #define trim_threshold malloc_trim_threshold
1653 #define top_pad malloc_top_pad
1654 #define n_mmaps_max malloc_n_mmaps_max
1655 #define mmap_threshold malloc_mmap_threshold
1656 #define sbrk_base malloc_sbrk_base
1657 #define max_sbrked_mem malloc_max_sbrked_mem
1658 #define max_total_mem malloc_max_total_mem
1659 #define current_mallinfo malloc_current_mallinfo
1660 #define n_mmaps malloc_n_mmaps
1661 #define max_n_mmaps malloc_max_n_mmaps
1662 #define mmapped_mem malloc_mmapped_mem
1663 #define max_mmapped_mem malloc_max_mmapped_mem
1664 #endif
1665
1666 /* variables holding tunable values */
1667
1668 #ifdef DEFINE_MALLOC
1669
1670 STATIC unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD;
1671 STATIC unsigned long top_pad = DEFAULT_TOP_PAD;
1672 #if HAVE_MMAP
1673 STATIC unsigned int n_mmaps_max = DEFAULT_MMAP_MAX;
1674 STATIC unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD;
1675 #endif
1676
1677 /* The first value returned from sbrk */
1678 STATIC char* sbrk_base = (char*)(-1);
1679
1680 /* The maximum memory obtained from system via sbrk */
1681 STATIC unsigned long max_sbrked_mem = 0;
1682
1683 /* The maximum via either sbrk or mmap */
1684 STATIC unsigned long max_total_mem = 0;
1685
1686 /* internal working copy of mallinfo */
1687 STATIC struct mallinfo current_mallinfo = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
1688
1689 #if HAVE_MMAP
1690
1691 /* Tracking mmaps */
1692
1693 STATIC unsigned int n_mmaps = 0;
1694 STATIC unsigned int max_n_mmaps = 0;
1695 STATIC unsigned long mmapped_mem = 0;
1696 STATIC unsigned long max_mmapped_mem = 0;
1697
1698 #endif
1699
1700 #else /* ! DEFINE_MALLOC */
1701
1702 extern unsigned long trim_threshold;
1703 extern unsigned long top_pad;
1704 #if HAVE_MMAP
1705 extern unsigned int n_mmaps_max;
1706 extern unsigned long mmap_threshold;
1707 #endif
1708 extern char* sbrk_base;
1709 extern unsigned long max_sbrked_mem;
1710 extern unsigned long max_total_mem;
1711 extern struct mallinfo current_mallinfo;
1712 #if HAVE_MMAP
1713 extern unsigned int n_mmaps;
1714 extern unsigned int max_n_mmaps;
1715 extern unsigned long mmapped_mem;
1716 extern unsigned long max_mmapped_mem;
1717 #endif
1718
1719 #endif /* ! DEFINE_MALLOC */
1720
1721 /* The total memory obtained from system via sbrk */
1722 #define sbrked_mem (current_mallinfo.arena)
1723
1724
1725
1726 /*
1727 Debugging support
1728 */
1729
1730 #if DEBUG
1731
1732
1733 /*
1734 These routines make a number of assertions about the states
1735 of data structures that should be true at all times. If any
1736 are not true, it's very likely that a user program has somehow
1737 trashed memory. (It's also possible that there is a coding error
1738 in malloc. In which case, please report it!)
1739 */
1740
1741 #if __STD_C
do_check_chunk(mchunkptr p)1742 static void do_check_chunk(mchunkptr p)
1743 #else
1744 static void do_check_chunk(p) mchunkptr p;
1745 #endif
1746 {
1747 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
1748
1749 /* No checkable chunk is mmapped */
1750 assert(!chunk_is_mmapped(p));
1751
1752 /* Check for legal address ... */
1753 assert((char*)p >= sbrk_base);
1754 if (p != top)
1755 assert((char*)p + sz <= (char*)top);
1756 else
1757 assert((char*)p + sz <= sbrk_base + sbrked_mem);
1758
1759 }
1760
1761
1762 #if __STD_C
do_check_free_chunk(mchunkptr p)1763 static void do_check_free_chunk(mchunkptr p)
1764 #else
1765 static void do_check_free_chunk(p) mchunkptr p;
1766 #endif
1767 {
1768 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
1769 mchunkptr next = chunk_at_offset(p, sz);
1770
1771 do_check_chunk(p);
1772
1773 /* Check whether it claims to be free ... */
1774 assert(!inuse(p));
1775
1776 /* Unless a special marker, must have OK fields */
1777 if ((long)sz >= (long)MINSIZE)
1778 {
1779 assert((sz & MALLOC_ALIGN_MASK) == 0);
1780 assert(aligned_OK(chunk2mem(p)));
1781 /* ... matching footer field */
1782 assert(next->prev_size == sz);
1783 /* ... and is fully consolidated */
1784 assert(prev_inuse(p));
1785 assert (next == top || inuse(next));
1786
1787 /* ... and has minimally sane links */
1788 assert(p->fd->bk == p);
1789 assert(p->bk->fd == p);
1790 }
1791 else /* markers are always of size SIZE_SZ */
1792 assert(sz == SIZE_SZ);
1793 }
1794
1795 #if __STD_C
do_check_inuse_chunk(mchunkptr p)1796 static void do_check_inuse_chunk(mchunkptr p)
1797 #else
1798 static void do_check_inuse_chunk(p) mchunkptr p;
1799 #endif
1800 {
1801 mchunkptr next = next_chunk(p);
1802 do_check_chunk(p);
1803
1804 /* Check whether it claims to be in use ... */
1805 assert(inuse(p));
1806
1807 /* ... and is surrounded by OK chunks.
1808 Since more things can be checked with free chunks than inuse ones,
1809 if an inuse chunk borders them and debug is on, it's worth doing them.
1810 */
1811 if (!prev_inuse(p))
1812 {
1813 mchunkptr prv = prev_chunk(p);
1814 assert(next_chunk(prv) == p);
1815 do_check_free_chunk(prv);
1816 }
1817 if (next == top)
1818 {
1819 assert(prev_inuse(next));
1820 assert(chunksize(next) >= MINSIZE);
1821 }
1822 else if (!inuse(next))
1823 do_check_free_chunk(next);
1824
1825 }
1826
1827 #if __STD_C
do_check_malloced_chunk(mchunkptr p,INTERNAL_SIZE_T s)1828 static void do_check_malloced_chunk(mchunkptr p, INTERNAL_SIZE_T s)
1829 #else
1830 static void do_check_malloced_chunk(p, s) mchunkptr p; INTERNAL_SIZE_T s;
1831 #endif
1832 {
1833 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
1834 long room = long_sub_size_t(sz, s);
1835
1836 do_check_inuse_chunk(p);
1837
1838 /* Legal size ... */
1839 assert((long)sz >= (long)MINSIZE);
1840 assert((sz & MALLOC_ALIGN_MASK) == 0);
1841 assert(room >= 0);
1842 assert(room < (long)MINSIZE);
1843
1844 /* ... and alignment */
1845 assert(aligned_OK(chunk2mem(p)));
1846
1847
1848 /* ... and was allocated at front of an available chunk */
1849 assert(prev_inuse(p));
1850
1851 }
1852
1853
1854 #define check_free_chunk(P) do_check_free_chunk(P)
1855 #define check_inuse_chunk(P) do_check_inuse_chunk(P)
1856 #define check_chunk(P) do_check_chunk(P)
1857 #define check_malloced_chunk(P,N) do_check_malloced_chunk(P,N)
1858 #else
1859 #define check_free_chunk(P)
1860 #define check_inuse_chunk(P)
1861 #define check_chunk(P)
1862 #define check_malloced_chunk(P,N)
1863 #endif
1864
1865
1866
1867 /*
1868 Macro-based internal utilities
1869 */
1870
1871
1872 /*
1873 Linking chunks in bin lists.
1874 Call these only with variables, not arbitrary expressions, as arguments.
1875 */
1876
1877 /*
1878 Place chunk p of size s in its bin, in size order,
1879 putting it ahead of others of same size.
1880 */
1881
1882
1883 #define frontlink(P, S, IDX, BK, FD) \
1884 { \
1885 if (S < MAX_SMALLBIN_SIZE) \
1886 { \
1887 IDX = smallbin_index(S); \
1888 mark_binblock(IDX); \
1889 BK = bin_at(IDX); \
1890 FD = BK->fd; \
1891 P->bk = BK; \
1892 P->fd = FD; \
1893 FD->bk = BK->fd = P; \
1894 } \
1895 else \
1896 { \
1897 IDX = bin_index(S); \
1898 BK = bin_at(IDX); \
1899 FD = BK->fd; \
1900 if (FD == BK) mark_binblock(IDX); \
1901 else \
1902 { \
1903 while (FD != BK && S < chunksize(FD)) FD = FD->fd; \
1904 BK = FD->bk; \
1905 } \
1906 P->bk = BK; \
1907 P->fd = FD; \
1908 FD->bk = BK->fd = P; \
1909 } \
1910 }
1911
1912
1913 /* take a chunk off a list */
1914
1915 #define unlink(P, BK, FD) \
1916 { \
1917 BK = P->bk; \
1918 FD = P->fd; \
1919 FD->bk = BK; \
1920 BK->fd = FD; \
1921 } \
1922
1923 /* Place p as the last remainder */
1924
1925 #define link_last_remainder(P) \
1926 { \
1927 last_remainder->fd = last_remainder->bk = P; \
1928 P->fd = P->bk = last_remainder; \
1929 }
1930
1931 /* Clear the last_remainder bin */
1932
1933 #define clear_last_remainder \
1934 (last_remainder->fd = last_remainder->bk = last_remainder)
1935
1936
1937
1938
1939
1940
1941 /* Routines dealing with mmap(). */
1942
1943 #if HAVE_MMAP
1944
1945 #ifdef DEFINE_MALLOC
1946
1947 #if __STD_C
mmap_chunk(size_t size)1948 static mchunkptr mmap_chunk(size_t size)
1949 #else
1950 static mchunkptr mmap_chunk(size) size_t size;
1951 #endif
1952 {
1953 size_t page_mask = malloc_getpagesize - 1;
1954 mchunkptr p;
1955
1956 #ifndef MAP_ANONYMOUS
1957 static int fd = -1;
1958 #endif
1959
1960 if(n_mmaps >= n_mmaps_max) return 0; /* too many regions */
1961
1962 /* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because
1963 * there is no following chunk whose prev_size field could be used.
1964 */
1965 size = (size + SIZE_SZ + page_mask) & ~page_mask;
1966
1967 #ifdef MAP_ANONYMOUS
1968 p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE,
1969 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
1970 #else /* !MAP_ANONYMOUS */
1971 if (fd < 0)
1972 {
1973 fd = open("/dev/zero", O_RDWR);
1974 if(fd < 0) return 0;
1975 }
1976 p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
1977 #endif
1978
1979 if(p == (mchunkptr)-1) return 0;
1980
1981 n_mmaps++;
1982 if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps;
1983
1984 /* We demand that eight bytes into a page must be 8-byte aligned. */
1985 assert(aligned_OK(chunk2mem(p)));
1986
1987 /* The offset to the start of the mmapped region is stored
1988 * in the prev_size field of the chunk; normally it is zero,
1989 * but that can be changed in memalign().
1990 */
1991 p->prev_size = 0;
1992 set_head(p, size|IS_MMAPPED);
1993
1994 mmapped_mem += size;
1995 if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
1996 max_mmapped_mem = mmapped_mem;
1997 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
1998 max_total_mem = mmapped_mem + sbrked_mem;
1999 return p;
2000 }
2001
2002 #endif /* DEFINE_MALLOC */
2003
2004 #ifdef SEPARATE_OBJECTS
2005 #define munmap_chunk malloc_munmap_chunk
2006 #endif
2007
2008 #ifdef DEFINE_FREE
2009
2010 #if __STD_C
munmap_chunk(mchunkptr p)2011 STATIC void munmap_chunk(mchunkptr p)
2012 #else
2013 STATIC void munmap_chunk(p) mchunkptr p;
2014 #endif
2015 {
2016 INTERNAL_SIZE_T size = chunksize(p);
2017 int ret;
2018
2019 assert (chunk_is_mmapped(p));
2020 assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
2021 assert((n_mmaps > 0));
2022 assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0);
2023
2024 n_mmaps--;
2025 mmapped_mem -= (size + p->prev_size);
2026
2027 ret = munmap((char *)p - p->prev_size, size + p->prev_size);
2028
2029 /* munmap returns non-zero on failure */
2030 assert(ret == 0);
2031 }
2032
2033 #else /* ! DEFINE_FREE */
2034
2035 #if __STD_C
2036 extern void munmap_chunk(mchunkptr);
2037 #else
2038 extern void munmap_chunk();
2039 #endif
2040
2041 #endif /* ! DEFINE_FREE */
2042
2043 #if HAVE_MREMAP
2044
2045 #ifdef DEFINE_REALLOC
2046
2047 #if __STD_C
mremap_chunk(mchunkptr p,size_t new_size)2048 static mchunkptr mremap_chunk(mchunkptr p, size_t new_size)
2049 #else
2050 static mchunkptr mremap_chunk(p, new_size) mchunkptr p; size_t new_size;
2051 #endif
2052 {
2053 size_t page_mask = malloc_getpagesize - 1;
2054 INTERNAL_SIZE_T offset = p->prev_size;
2055 INTERNAL_SIZE_T size = chunksize(p);
2056 char *cp;
2057
2058 assert (chunk_is_mmapped(p));
2059 assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
2060 assert((n_mmaps > 0));
2061 assert(((size + offset) & (malloc_getpagesize-1)) == 0);
2062
2063 /* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
2064 new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask;
2065
2066 cp = (char *)mremap((char *)p - offset, size + offset, new_size, 1);
2067
2068 if (cp == (char *)-1) return 0;
2069
2070 p = (mchunkptr)(cp + offset);
2071
2072 assert(aligned_OK(chunk2mem(p)));
2073
2074 assert((p->prev_size == offset));
2075 set_head(p, (new_size - offset)|IS_MMAPPED);
2076
2077 mmapped_mem -= size + offset;
2078 mmapped_mem += new_size;
2079 if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
2080 max_mmapped_mem = mmapped_mem;
2081 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
2082 max_total_mem = mmapped_mem + sbrked_mem;
2083 return p;
2084 }
2085
2086 #endif /* DEFINE_REALLOC */
2087
2088 #endif /* HAVE_MREMAP */
2089
2090 #endif /* HAVE_MMAP */
2091
2092
2093
2094
2095 #ifdef DEFINE_MALLOC
2096
2097 /*
2098 Extend the top-most chunk by obtaining memory from system.
2099 Main interface to sbrk (but see also malloc_trim).
2100 */
2101
2102 #if __STD_C
malloc_extend_top(INTERNAL_SIZE_T nb)2103 static void malloc_extend_top(INTERNAL_SIZE_T nb)
2104 #else
2105 static void malloc_extend_top(nb) RDECL INTERNAL_SIZE_T nb;
2106 #endif
2107 {
2108 char* brk; /* return value from sbrk */
2109 INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */
2110 INTERNAL_SIZE_T correction; /* bytes for 2nd sbrk call */
2111 int correction_failed = 0; /* whether we should relax the assertion */
2112 char* new_brk; /* return of 2nd sbrk call */
2113 INTERNAL_SIZE_T top_size; /* new size of top chunk */
2114
2115 mchunkptr old_top = top; /* Record state of old top */
2116 INTERNAL_SIZE_T old_top_size = chunksize(old_top);
2117 char* old_end = (char*)(chunk_at_offset(old_top, old_top_size));
2118
2119 /* Pad request with top_pad plus minimal overhead */
2120
2121 INTERNAL_SIZE_T sbrk_size = nb + top_pad + MINSIZE;
2122 unsigned long pagesz = malloc_getpagesize;
2123
2124 /* If not the first time through, round to preserve page boundary */
2125 /* Otherwise, we need to correct to a page size below anyway. */
2126 /* (We also correct below if an intervening foreign sbrk call.) */
2127
2128 if (sbrk_base != (char*)(-1))
2129 sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1);
2130
2131 brk = (char*)(MORECORE (sbrk_size));
2132
2133 /* Fail if sbrk failed or if a foreign sbrk call killed our space */
2134 if (brk == (char*)(MORECORE_FAILURE) ||
2135 (brk < old_end && old_top != initial_top))
2136 return;
2137
2138 sbrked_mem += sbrk_size;
2139
2140 if (brk == old_end /* can just add bytes to current top, unless
2141 previous correction failed */
2142 && ((POINTER_UINT)old_end & (pagesz - 1)) == 0)
2143 {
2144 top_size = sbrk_size + old_top_size;
2145 set_head(top, top_size | PREV_INUSE);
2146 }
2147 else
2148 {
2149 if (sbrk_base == (char*)(-1)) /* First time through. Record base */
2150 sbrk_base = brk;
2151 else /* Someone else called sbrk(). Count those bytes as sbrked_mem. */
2152 sbrked_mem += brk - (char*)old_end;
2153
2154 /* Guarantee alignment of first new chunk made from this space */
2155 front_misalign = (POINTER_UINT)chunk2mem(brk) & MALLOC_ALIGN_MASK;
2156 if (front_misalign > 0)
2157 {
2158 correction = (MALLOC_ALIGNMENT) - front_misalign;
2159 brk += correction;
2160 }
2161 else
2162 correction = 0;
2163
2164 /* Guarantee the next brk will be at a page boundary */
2165 correction += pagesz - ((POINTER_UINT)(brk + sbrk_size) & (pagesz - 1));
2166
2167 /* To guarantee page boundary, correction should be less than pagesz */
2168 correction &= (pagesz - 1);
2169
2170 /* Allocate correction */
2171 new_brk = (char*)(MORECORE (correction));
2172 if (new_brk == (char*)(MORECORE_FAILURE))
2173 {
2174 correction = 0;
2175 correction_failed = 1;
2176 new_brk = brk + sbrk_size;
2177 if (front_misalign > 0)
2178 new_brk -= (MALLOC_ALIGNMENT) - front_misalign;
2179 }
2180
2181 sbrked_mem += correction;
2182
2183 top = (mchunkptr)brk;
2184 top_size = new_brk - brk + correction;
2185 set_head(top, top_size | PREV_INUSE);
2186
2187 if (old_top != initial_top)
2188 {
2189
2190 /* There must have been an intervening foreign sbrk call. */
2191 /* A double fencepost is necessary to prevent consolidation */
2192
2193 /* If not enough space to do this, then user did something very wrong */
2194 if (old_top_size < MINSIZE)
2195 {
2196 set_head(top, PREV_INUSE); /* will force null return from malloc */
2197 return;
2198 }
2199
2200 /* Also keep size a multiple of MALLOC_ALIGNMENT */
2201 old_top_size = (old_top_size - 3*SIZE_SZ) & ~MALLOC_ALIGN_MASK;
2202 set_head_size(old_top, old_top_size);
2203 chunk_at_offset(old_top, old_top_size )->size =
2204 SIZE_SZ|PREV_INUSE;
2205 chunk_at_offset(old_top, old_top_size + SIZE_SZ)->size =
2206 SIZE_SZ|PREV_INUSE;
2207 /* If possible, release the rest. */
2208 if (old_top_size >= MINSIZE)
2209 __malloc_free(chunk2mem(old_top));
2210 }
2211 }
2212
2213 if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem)
2214 max_sbrked_mem = sbrked_mem;
2215 #if HAVE_MMAP
2216 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
2217 max_total_mem = mmapped_mem + sbrked_mem;
2218 #else
2219 if ((unsigned long)(sbrked_mem) > (unsigned long)max_total_mem)
2220 max_total_mem = sbrked_mem;
2221 #endif
2222
2223 /* We always land on a page boundary */
2224 assert(((unsigned long)((char*)top + top_size) & (pagesz - 1)) == 0
2225 || correction_failed);
2226 (void) correction_failed;
2227 }
2228
2229 #endif /* DEFINE_MALLOC */
2230
2231
2232 /* Main public routines */
2233
2234 #ifdef DEFINE_MALLOC
2235
2236 /*
2237 Malloc Algorthim:
2238
2239 The requested size is first converted into a usable form, `nb'.
2240 This currently means to add 4 bytes overhead plus possibly more to
2241 obtain 8-byte alignment and/or to obtain a size of at least
2242 MINSIZE (currently 16 bytes), the smallest allocatable size.
2243 (All fits are considered `exact' if they are within MINSIZE bytes.)
2244
2245 From there, the first successful of the following steps is taken:
2246
2247 1. The bin corresponding to the request size is scanned, and if
2248 a chunk of exactly the right size is found, it is taken.
2249
2250 2. The most recently remaindered chunk is used if it is big
2251 enough. This is a form of (roving) first fit, used only in
2252 the absence of exact fits. Runs of consecutive requests use
2253 the remainder of the chunk used for the previous such request
2254 whenever possible. This limited use of a first-fit style
2255 allocation strategy tends to give contiguous chunks
2256 coextensive lifetimes, which improves locality and can reduce
2257 fragmentation in the long run.
2258
2259 3. Other bins are scanned in increasing size order, using a
2260 chunk big enough to fulfill the request, and splitting off
2261 any remainder. This search is strictly by best-fit; i.e.,
2262 the smallest (with ties going to approximately the least
2263 recently used) chunk that fits is selected.
2264
2265 4. If large enough, the chunk bordering the end of memory
2266 (`top') is split off. (This use of `top' is in accord with
2267 the best-fit search rule. In effect, `top' is treated as
2268 larger (and thus less well fitting) than any other available
2269 chunk since it can be extended to be as large as necessary
2270 (up to system limitations).
2271
2272 5. If the request size meets the mmap threshold and the
2273 system supports mmap, and there are few enough currently
2274 allocated mmapped regions, and a call to mmap succeeds,
2275 the request is allocated via direct memory mapping.
2276
2277 6. Otherwise, the top of memory is extended by
2278 obtaining more space from the system (normally using sbrk,
2279 but definable to anything else via the MORECORE macro).
2280 Memory is gathered from the system (in system page-sized
2281 units) in a way that allows chunks obtained across different
2282 sbrk calls to be consolidated, but does not require
2283 contiguous memory. Thus, it should be safe to intersperse
2284 mallocs with other sbrk calls.
2285
2286
2287 All allocations are made from the the `lowest' part of any found
2288 chunk. (The implementation invariant is that prev_inuse is
2289 always true of any allocated chunk; i.e., that each allocated
2290 chunk borders either a previously allocated and still in-use chunk,
2291 or the base of its memory arena.)
2292
2293 */
2294
2295 #if __STD_C
mALLOc(size_t bytes)2296 Void_t* mALLOc(size_t bytes)
2297 #else
2298 Void_t* mALLOc(bytes) RDECL size_t bytes;
2299 #endif
2300 {
2301 #ifdef MALLOC_PROVIDED
2302
2303 return malloc (bytes); // Make sure that the pointer returned by malloc is returned back.
2304
2305 #else
2306
2307 mchunkptr victim; /* inspected/selected chunk */
2308 INTERNAL_SIZE_T victim_size; /* its size */
2309 int idx; /* index for bin traversal */
2310 mbinptr bin; /* associated bin */
2311 mchunkptr remainder; /* remainder from a split */
2312 long remainder_size; /* its size */
2313 int remainder_index; /* its bin index */
2314 unsigned long block; /* block traverser bit */
2315 int startidx; /* first bin of a traversed block */
2316 mchunkptr fwd; /* misc temp for linking */
2317 mchunkptr bck; /* misc temp for linking */
2318 mbinptr q; /* misc temp */
2319
2320 INTERNAL_SIZE_T nb = request2size(bytes); /* padded request size; */
2321
2322 /* Check for overflow and just fail, if so. */
2323 if (nb > INT_MAX || nb < bytes)
2324 {
2325 errno = ENOMEM;
2326 return 0;
2327 }
2328
2329 MALLOC_LOCK;
2330
2331 /* Check for exact match in a bin */
2332
2333 if (is_small_request(nb)) /* Faster version for small requests */
2334 {
2335 idx = smallbin_index(nb);
2336
2337 /* No traversal or size check necessary for small bins. */
2338
2339 q = bin_at(idx);
2340 victim = last(q);
2341
2342 #if MALLOC_ALIGN != 16
2343 /* Also scan the next one, since it would have a remainder < MINSIZE */
2344 if (victim == q)
2345 {
2346 q = next_bin(q);
2347 victim = last(q);
2348 }
2349 #endif
2350 if (victim != q)
2351 {
2352 victim_size = chunksize(victim);
2353 unlink(victim, bck, fwd);
2354 set_inuse_bit_at_offset(victim, victim_size);
2355 check_malloced_chunk(victim, nb);
2356 MALLOC_UNLOCK;
2357 return chunk2mem(victim);
2358 }
2359
2360 idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */
2361
2362 }
2363 else
2364 {
2365 idx = bin_index(nb);
2366 bin = bin_at(idx);
2367
2368 for (victim = last(bin); victim != bin; victim = victim->bk)
2369 {
2370 victim_size = chunksize(victim);
2371 remainder_size = long_sub_size_t(victim_size, nb);
2372
2373 if (remainder_size >= (long)MINSIZE) /* too big */
2374 {
2375 --idx; /* adjust to rescan below after checking last remainder */
2376 break;
2377 }
2378
2379 else if (remainder_size >= 0) /* exact fit */
2380 {
2381 unlink(victim, bck, fwd);
2382 set_inuse_bit_at_offset(victim, victim_size);
2383 check_malloced_chunk(victim, nb);
2384 MALLOC_UNLOCK;
2385 return chunk2mem(victim);
2386 }
2387 }
2388
2389 ++idx;
2390
2391 }
2392
2393 /* Try to use the last split-off remainder */
2394
2395 if ( (victim = last_remainder->fd) != last_remainder)
2396 {
2397 victim_size = chunksize(victim);
2398 remainder_size = long_sub_size_t(victim_size, nb);
2399
2400 if (remainder_size >= (long)MINSIZE) /* re-split */
2401 {
2402 remainder = chunk_at_offset(victim, nb);
2403 set_head(victim, nb | PREV_INUSE);
2404 link_last_remainder(remainder);
2405 set_head(remainder, remainder_size | PREV_INUSE);
2406 set_foot(remainder, remainder_size);
2407 check_malloced_chunk(victim, nb);
2408 MALLOC_UNLOCK;
2409 return chunk2mem(victim);
2410 }
2411
2412 clear_last_remainder;
2413
2414 if (remainder_size >= 0) /* exhaust */
2415 {
2416 set_inuse_bit_at_offset(victim, victim_size);
2417 check_malloced_chunk(victim, nb);
2418 MALLOC_UNLOCK;
2419 return chunk2mem(victim);
2420 }
2421
2422 /* Else place in bin */
2423
2424 frontlink(victim, victim_size, remainder_index, bck, fwd);
2425 }
2426
2427 /*
2428 If there are any possibly nonempty big-enough blocks,
2429 search for best fitting chunk by scanning bins in blockwidth units.
2430 */
2431
2432 if ( (block = idx2binblock(idx)) <= binblocks)
2433 {
2434
2435 /* Get to the first marked block */
2436
2437 if ( (block & binblocks) == 0)
2438 {
2439 /* force to an even block boundary */
2440 idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH;
2441 block <<= 1;
2442 while ((block & binblocks) == 0)
2443 {
2444 idx += BINBLOCKWIDTH;
2445 block <<= 1;
2446 }
2447 }
2448
2449 /* For each possibly nonempty block ... */
2450 for (;;)
2451 {
2452 startidx = idx; /* (track incomplete blocks) */
2453 q = bin = bin_at(idx);
2454
2455 /* For each bin in this block ... */
2456 do
2457 {
2458 /* Find and use first big enough chunk ... */
2459
2460 for (victim = last(bin); victim != bin; victim = victim->bk)
2461 {
2462 victim_size = chunksize(victim);
2463 remainder_size = long_sub_size_t(victim_size, nb);
2464
2465 if (remainder_size >= (long)MINSIZE) /* split */
2466 {
2467 remainder = chunk_at_offset(victim, nb);
2468 set_head(victim, nb | PREV_INUSE);
2469 unlink(victim, bck, fwd);
2470 link_last_remainder(remainder);
2471 set_head(remainder, remainder_size | PREV_INUSE);
2472 set_foot(remainder, remainder_size);
2473 check_malloced_chunk(victim, nb);
2474 MALLOC_UNLOCK;
2475 return chunk2mem(victim);
2476 }
2477
2478 else if (remainder_size >= 0) /* take */
2479 {
2480 set_inuse_bit_at_offset(victim, victim_size);
2481 unlink(victim, bck, fwd);
2482 check_malloced_chunk(victim, nb);
2483 MALLOC_UNLOCK;
2484 return chunk2mem(victim);
2485 }
2486
2487 }
2488
2489 bin = next_bin(bin);
2490
2491 #if MALLOC_ALIGN == 16
2492 if (idx < MAX_SMALLBIN)
2493 {
2494 bin = next_bin(bin);
2495 ++idx;
2496 }
2497 #endif
2498 } while ((++idx & (BINBLOCKWIDTH - 1)) != 0);
2499
2500 /* Clear out the block bit. */
2501
2502 do /* Possibly backtrack to try to clear a partial block */
2503 {
2504 if ((startidx & (BINBLOCKWIDTH - 1)) == 0)
2505 {
2506 binblocks &= ~block;
2507 break;
2508 }
2509 --startidx;
2510 q = prev_bin(q);
2511 } while (first(q) == q);
2512
2513 /* Get to the next possibly nonempty block */
2514
2515 if ( (block <<= 1) <= binblocks && (block != 0) )
2516 {
2517 while ((block & binblocks) == 0)
2518 {
2519 idx += BINBLOCKWIDTH;
2520 block <<= 1;
2521 }
2522 }
2523 else
2524 break;
2525 }
2526 }
2527
2528
2529 /* Try to use top chunk */
2530
2531 /* Require that there be a remainder, ensuring top always exists */
2532 remainder_size = long_sub_size_t(chunksize(top), nb);
2533 if (chunksize(top) < nb || remainder_size < (long)MINSIZE)
2534 {
2535
2536 #if HAVE_MMAP
2537 /* If big and would otherwise need to extend, try to use mmap instead */
2538 if ((unsigned long)nb >= (unsigned long)mmap_threshold &&
2539 (victim = mmap_chunk(nb)) != 0)
2540 {
2541 MALLOC_UNLOCK;
2542 return chunk2mem(victim);
2543 }
2544 #endif
2545
2546 /* Try to extend */
2547 malloc_extend_top(nb);
2548 remainder_size = long_sub_size_t(chunksize(top), nb);
2549 if (chunksize(top) < nb || remainder_size < (long)MINSIZE)
2550 {
2551 MALLOC_UNLOCK;
2552 return 0; /* propagate failure */
2553 }
2554 }
2555
2556 victim = top;
2557 set_head(victim, nb | PREV_INUSE);
2558 top = chunk_at_offset(victim, nb);
2559 set_head(top, remainder_size | PREV_INUSE);
2560 check_malloced_chunk(victim, nb);
2561 MALLOC_UNLOCK;
2562 return chunk2mem(victim);
2563
2564 #endif /* MALLOC_PROVIDED */
2565 }
2566
2567 #endif /* DEFINE_MALLOC */
2568
2569 #ifdef DEFINE_FREE
2570
2571 /*
2572
2573 free() algorithm :
2574
2575 cases:
2576
2577 1. free(0) has no effect.
2578
2579 2. If the chunk was allocated via mmap, it is release via munmap().
2580
2581 3. If a returned chunk borders the current high end of memory,
2582 it is consolidated into the top, and if the total unused
2583 topmost memory exceeds the trim threshold, malloc_trim is
2584 called.
2585
2586 4. Other chunks are consolidated as they arrive, and
2587 placed in corresponding bins. (This includes the case of
2588 consolidating with the current `last_remainder').
2589
2590 */
2591
2592
2593 #if __STD_C
fREe(Void_t * mem)2594 void fREe(Void_t* mem)
2595 #else
2596 void fREe(mem) RDECL Void_t* mem;
2597 #endif
2598 {
2599 #ifdef MALLOC_PROVIDED
2600
2601 free (mem);
2602
2603 #else
2604
2605 mchunkptr p; /* chunk corresponding to mem */
2606 INTERNAL_SIZE_T hd; /* its head field */
2607 INTERNAL_SIZE_T sz; /* its size */
2608 int idx; /* its bin index */
2609 mchunkptr next; /* next contiguous chunk */
2610 INTERNAL_SIZE_T nextsz; /* its size */
2611 INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */
2612 mchunkptr bck; /* misc temp for linking */
2613 mchunkptr fwd; /* misc temp for linking */
2614 int islr; /* track whether merging with last_remainder */
2615
2616 if (mem == 0) /* free(0) has no effect */
2617 return;
2618
2619 MALLOC_LOCK;
2620
2621 p = mem2chunk(mem);
2622 hd = p->size;
2623
2624 #if HAVE_MMAP
2625 if (hd & IS_MMAPPED) /* release mmapped memory. */
2626 {
2627 munmap_chunk(p);
2628 MALLOC_UNLOCK;
2629 return;
2630 }
2631 #endif
2632
2633 check_inuse_chunk(p);
2634
2635 sz = hd & ~PREV_INUSE;
2636 next = chunk_at_offset(p, sz);
2637 nextsz = chunksize(next);
2638
2639 if (next == top) /* merge with top */
2640 {
2641 sz += nextsz;
2642
2643 if (!(hd & PREV_INUSE)) /* consolidate backward */
2644 {
2645 prevsz = p->prev_size;
2646 p = chunk_at_offset(p, -prevsz);
2647 sz += prevsz;
2648 unlink(p, bck, fwd);
2649 }
2650
2651 set_head(p, sz | PREV_INUSE);
2652 top = p;
2653 if ((unsigned long)(sz) >= (unsigned long)trim_threshold)
2654 malloc_trim(top_pad);
2655 MALLOC_UNLOCK;
2656 return;
2657 }
2658
2659 set_head(next, nextsz); /* clear inuse bit */
2660
2661 islr = 0;
2662
2663 if (!(hd & PREV_INUSE)) /* consolidate backward */
2664 {
2665 prevsz = p->prev_size;
2666 p = chunk_at_offset(p, -prevsz);
2667 sz += prevsz;
2668
2669 if (p->fd == last_remainder) /* keep as last_remainder */
2670 islr = 1;
2671 else
2672 unlink(p, bck, fwd);
2673 }
2674
2675 if (!(inuse_bit_at_offset(next, nextsz))) /* consolidate forward */
2676 {
2677 sz += nextsz;
2678
2679 if (!islr && next->fd == last_remainder) /* re-insert last_remainder */
2680 {
2681 islr = 1;
2682 link_last_remainder(p);
2683 }
2684 else
2685 unlink(next, bck, fwd);
2686 }
2687
2688
2689 set_head(p, sz | PREV_INUSE);
2690 set_foot(p, sz);
2691 if (!islr)
2692 frontlink(p, sz, idx, bck, fwd);
2693
2694 MALLOC_UNLOCK;
2695
2696 #endif /* MALLOC_PROVIDED */
2697 }
2698 #ifdef _HAVE_ALIAS_ATTRIBUTE
2699 #pragma GCC diagnostic push
2700 #ifndef __clang__
2701 #pragma GCC diagnostic ignored "-Wmissing-attributes"
2702 #endif
2703 __strong_reference(free, __malloc_free);
2704 #pragma GCC diagnostic pop
2705 #endif
2706 #endif /* DEFINE_FREE */
2707
2708 #ifdef DEFINE_REALLOC
2709
2710 /*
2711
2712 Realloc algorithm:
2713
2714 Chunks that were obtained via mmap cannot be extended or shrunk
2715 unless HAVE_MREMAP is defined, in which case mremap is used.
2716 Otherwise, if their reallocation is for additional space, they are
2717 copied. If for less, they are just left alone.
2718
2719 Otherwise, if the reallocation is for additional space, and the
2720 chunk can be extended, it is, else a malloc-copy-free sequence is
2721 taken. There are several different ways that a chunk could be
2722 extended. All are tried:
2723
2724 * Extending forward into following adjacent free chunk.
2725 * Shifting backwards, joining preceding adjacent space
2726 * Both shifting backwards and extending forward.
2727 * Extending into newly sbrked space
2728
2729 Unless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with a
2730 size argument of zero (re)allocates a minimum-sized chunk.
2731
2732 If the reallocation is for less space, and the new request is for
2733 a `small' (<512 bytes) size, then the newly unused space is lopped
2734 off and freed.
2735
2736 The old unix realloc convention of allowing the last-free'd chunk
2737 to be used as an argument to realloc is no longer supported.
2738 I don't know of any programs still relying on this feature,
2739 and allowing it would also allow too many other incorrect
2740 usages of realloc to be sensible.
2741
2742
2743 */
2744
2745
2746 #if __STD_C
rEALLOc(Void_t * oldmem,size_t bytes)2747 Void_t* rEALLOc(Void_t* oldmem, size_t bytes)
2748 #else
2749 Void_t* rEALLOc(oldmem, bytes) RDECL Void_t* oldmem; size_t bytes;
2750 #endif
2751 {
2752 #ifdef MALLOC_PROVIDED
2753
2754 realloc (oldmem, bytes);
2755
2756 #else
2757
2758 INTERNAL_SIZE_T nb; /* padded request size */
2759
2760 mchunkptr oldp; /* chunk corresponding to oldmem */
2761 INTERNAL_SIZE_T oldsize; /* its size */
2762
2763 mchunkptr newp; /* chunk to return */
2764 INTERNAL_SIZE_T newsize; /* its size */
2765 Void_t* newmem; /* corresponding user mem */
2766
2767 mchunkptr next; /* next contiguous chunk after oldp */
2768 INTERNAL_SIZE_T nextsize; /* its size */
2769
2770 mchunkptr prev; /* previous contiguous chunk before oldp */
2771 INTERNAL_SIZE_T prevsize; /* its size */
2772
2773 mchunkptr remainder; /* holds split off extra space from newp */
2774 INTERNAL_SIZE_T remainder_size; /* its size */
2775
2776 mchunkptr bck; /* misc temp for linking */
2777 mchunkptr fwd; /* misc temp for linking */
2778
2779 #ifdef REALLOC_ZERO_BYTES_FREES
2780 if (bytes == 0) { fREe(oldmem); return 0; }
2781 #endif
2782
2783
2784 /* realloc of null is supposed to be same as malloc */
2785 if (oldmem == 0) return mALLOc(bytes);
2786
2787 MALLOC_LOCK;
2788
2789 newp = oldp = mem2chunk(oldmem);
2790 newsize = oldsize = chunksize(oldp);
2791
2792
2793 nb = request2size(bytes);
2794
2795 /* Check for overflow and just fail, if so. */
2796 if (nb > INT_MAX || nb < bytes)
2797 {
2798 errno = ENOMEM;
2799 return 0;
2800 }
2801
2802 #if HAVE_MMAP
2803 if (chunk_is_mmapped(oldp))
2804 {
2805 #if HAVE_MREMAP
2806 newp = mremap_chunk(oldp, nb);
2807 if(newp)
2808 {
2809 MALLOC_UNLOCK;
2810 return chunk2mem(newp);
2811 }
2812 #endif
2813 /* Note the extra SIZE_SZ overhead. */
2814 if(oldsize - SIZE_SZ >= nb)
2815 {
2816 MALLOC_UNLOCK;
2817 return oldmem; /* do nothing */
2818 }
2819 /* Must alloc, copy, free. */
2820 newmem = mALLOc(bytes);
2821 if (newmem == 0)
2822 {
2823 MALLOC_UNLOCK;
2824 return 0; /* propagate failure */
2825 }
2826 MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ);
2827 munmap_chunk(oldp);
2828 MALLOC_UNLOCK;
2829 return newmem;
2830 }
2831 #endif
2832
2833 check_inuse_chunk(oldp);
2834
2835 if ((long)(oldsize) < (long)(nb))
2836 {
2837
2838 /* Try expanding forward */
2839
2840 next = chunk_at_offset(oldp, oldsize);
2841 if (next == top || !inuse(next))
2842 {
2843 nextsize = chunksize(next);
2844
2845 /* Forward into top only if a remainder */
2846 if (next == top)
2847 {
2848 if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE))
2849 {
2850 newsize += nextsize;
2851 top = chunk_at_offset(oldp, nb);
2852 set_head(top, (newsize - nb) | PREV_INUSE);
2853 set_head_size(oldp, nb);
2854 MALLOC_UNLOCK;
2855 return chunk2mem(oldp);
2856 }
2857 }
2858
2859 /* Forward into next chunk */
2860 else if (((long)(nextsize + newsize) >= (long)(nb)))
2861 {
2862 unlink(next, bck, fwd);
2863 newsize += nextsize;
2864 goto split;
2865 }
2866 }
2867 else
2868 {
2869 next = 0;
2870 nextsize = 0;
2871 }
2872
2873 /* Try shifting backwards. */
2874
2875 if (!prev_inuse(oldp))
2876 {
2877 prev = prev_chunk(oldp);
2878 prevsize = chunksize(prev);
2879
2880 /* try forward + backward first to save a later consolidation */
2881
2882 if (next != 0)
2883 {
2884 /* into top */
2885 if (next == top)
2886 {
2887 if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE))
2888 {
2889 unlink(prev, bck, fwd);
2890 newp = prev;
2891 newsize += prevsize + nextsize;
2892 newmem = chunk2mem(newp);
2893 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
2894 top = chunk_at_offset(newp, nb);
2895 set_head(top, (newsize - nb) | PREV_INUSE);
2896 set_head_size(newp, nb);
2897 MALLOC_UNLOCK;
2898 return newmem;
2899 }
2900 }
2901
2902 /* into next chunk */
2903 else if (((long)(nextsize + prevsize + newsize) >= (long)(nb)))
2904 {
2905 unlink(next, bck, fwd);
2906 unlink(prev, bck, fwd);
2907 newp = prev;
2908 newsize += nextsize + prevsize;
2909 newmem = chunk2mem(newp);
2910 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
2911 goto split;
2912 }
2913 }
2914
2915 /* backward only */
2916 if (prev != 0 && (long)(prevsize + newsize) >= (long)nb)
2917 {
2918 unlink(prev, bck, fwd);
2919 newp = prev;
2920 newsize += prevsize;
2921 newmem = chunk2mem(newp);
2922 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
2923 goto split;
2924 }
2925 }
2926
2927 /* Must allocate */
2928
2929 newmem = mALLOc (bytes);
2930
2931 if (newmem == 0) /* propagate failure */
2932 {
2933 MALLOC_UNLOCK;
2934 return 0;
2935 }
2936
2937 /* Avoid copy if newp is next chunk after oldp. */
2938 /* (This can only happen when new chunk is sbrk'ed.) */
2939
2940 if ( (newp = mem2chunk(newmem)) == next_chunk(oldp))
2941 {
2942 newsize += chunksize(newp);
2943 newp = oldp;
2944 goto split;
2945 }
2946
2947 /* Otherwise copy, free, and exit */
2948 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
2949 __malloc_free(oldmem);
2950 MALLOC_UNLOCK;
2951 return newmem;
2952 }
2953
2954
2955 split: /* split off extra room in old or expanded chunk */
2956
2957 remainder_size = long_sub_size_t(newsize, nb);
2958
2959 if (remainder_size >= (long)MINSIZE) /* split off remainder */
2960 {
2961 remainder = chunk_at_offset(newp, nb);
2962 set_head_size(newp, nb);
2963 set_head(remainder, remainder_size | PREV_INUSE);
2964 set_inuse_bit_at_offset(remainder, remainder_size);
2965 __malloc_free(chunk2mem(remainder)); /* let free() deal with it */
2966 }
2967 else
2968 {
2969 set_head_size(newp, newsize);
2970 set_inuse_bit_at_offset(newp, newsize);
2971 }
2972
2973 check_inuse_chunk(newp);
2974 MALLOC_UNLOCK;
2975 return chunk2mem(newp);
2976
2977 #endif /* MALLOC_PROVIDED */
2978 }
2979
2980 #endif /* DEFINE_REALLOC */
2981
2982 #ifdef DEFINE_MEMALIGN
2983
2984 /*
2985
2986 memalign algorithm:
2987
2988 memalign requests more than enough space from malloc, finds a spot
2989 within that chunk that meets the alignment request, and then
2990 possibly frees the leading and trailing space.
2991
2992 The alignment argument must be a power of two. This property is not
2993 checked by memalign, so misuse may result in random runtime errors.
2994
2995 8-byte alignment is guaranteed by normal malloc calls, so don't
2996 bother calling memalign with an argument of 8 or less.
2997
2998 Overreliance on memalign is a sure way to fragment space.
2999
3000 */
3001
3002
3003 #if __STD_C
mEMALIGn(size_t alignment,size_t bytes)3004 Void_t* mEMALIGn(size_t alignment, size_t bytes)
3005 #else
3006 Void_t* mEMALIGn(alignment, bytes) RDECL size_t alignment; size_t bytes;
3007 #endif
3008 {
3009 INTERNAL_SIZE_T nb; /* padded request size */
3010 char* m; /* memory returned by malloc call */
3011 mchunkptr p; /* corresponding chunk */
3012 char* brk; /* alignment point within p */
3013 mchunkptr newp; /* chunk to return */
3014 INTERNAL_SIZE_T newsize; /* its size */
3015 INTERNAL_SIZE_T leadsize; /* leading space befor alignment point */
3016 mchunkptr remainder; /* spare room at end to split off */
3017 long remainder_size; /* its size */
3018
3019 /* If need less alignment than we give anyway, just relay to malloc */
3020
3021 if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes);
3022
3023 /* Otherwise, ensure that it is at least a minimum chunk size */
3024
3025 if (alignment < MINSIZE) alignment = MINSIZE;
3026
3027 /* Call malloc with worst case padding to hit alignment. */
3028
3029 nb = request2size(bytes);
3030
3031 /* Check for overflow. */
3032 if (nb > __SIZE_MAX__ - (alignment + MINSIZE) || nb < bytes)
3033 {
3034 errno = ENOMEM;
3035 return 0;
3036 }
3037
3038 m = (char*)(mALLOc(nb + alignment + MINSIZE));
3039
3040 if (m == 0) return 0; /* propagate failure */
3041
3042 MALLOC_LOCK;
3043
3044 p = mem2chunk(m);
3045
3046 if ((((uintptr_t)(m)) % alignment) == 0) /* aligned */
3047 {
3048 #if HAVE_MMAP
3049 if(chunk_is_mmapped(p))
3050 {
3051 MALLOC_UNLOCK;
3052 return chunk2mem(p); /* nothing more to do */
3053 }
3054 #endif
3055 }
3056 else /* misaligned */
3057 {
3058 /*
3059 Find an aligned spot inside chunk.
3060 Since we need to give back leading space in a chunk of at
3061 least MINSIZE, if the first calculation places us at
3062 a spot with less than MINSIZE leader, we can move to the
3063 next aligned spot -- we've allocated enough total room so that
3064 this is always possible.
3065 */
3066
3067 brk = (char*)mem2chunk(((uintptr_t)(m + alignment - 1)) & -alignment);
3068 if ((long)(brk - (char*)(p)) < (long)MINSIZE) brk = brk + alignment;
3069
3070 newp = (mchunkptr)brk;
3071 leadsize = brk - (char*)(p);
3072 newsize = chunksize(p) - leadsize;
3073
3074 #if HAVE_MMAP
3075 if(chunk_is_mmapped(p))
3076 {
3077 newp->prev_size = p->prev_size + leadsize;
3078 set_head(newp, newsize|IS_MMAPPED);
3079 MALLOC_UNLOCK;
3080 return chunk2mem(newp);
3081 }
3082 #endif
3083
3084 /* give back leader, use the rest */
3085
3086 set_head(newp, newsize | PREV_INUSE);
3087 set_inuse_bit_at_offset(newp, newsize);
3088 set_head_size(p, leadsize);
3089 __malloc_free(chunk2mem(p));
3090 p = newp;
3091
3092 assert (newsize >= nb && (((unsigned long)(chunk2mem(p))) % alignment) == 0);
3093 }
3094
3095 /* Also give back spare room at the end */
3096
3097 remainder_size = long_sub_size_t(chunksize(p), nb);
3098
3099 if (remainder_size >= (long)MINSIZE)
3100 {
3101 remainder = chunk_at_offset(p, nb);
3102 set_head(remainder, remainder_size | PREV_INUSE);
3103 set_head_size(p, nb);
3104 __malloc_free(chunk2mem(remainder));
3105 }
3106
3107 check_inuse_chunk(p);
3108 MALLOC_UNLOCK;
3109 return chunk2mem(p);
3110
3111 }
3112
3113 #ifdef _HAVE_ALIAS_ATTRIBUTE
3114 __strong_reference(memalign, aligned_alloc);
3115 #endif
3116 #endif /* DEFINE_MEMALIGN */
3117
3118 #ifdef DEFINE_VALLOC
3119
3120 /*
3121 valloc just invokes memalign with alignment argument equal
3122 to the page size of the system (or as near to this as can
3123 be figured out from all the includes/defines above.)
3124 */
3125
3126 #if __STD_C
vALLOc(size_t bytes)3127 Void_t* vALLOc(size_t bytes)
3128 #else
3129 Void_t* vALLOc(bytes) RDECL size_t bytes;
3130 #endif
3131 {
3132 return mEMALIGn (malloc_getpagesize, bytes);
3133 }
3134
3135 #endif /* DEFINE_VALLOC */
3136
3137 #ifdef DEFINE_PVALLOC
3138
3139 /*
3140 pvalloc just invokes valloc for the nearest pagesize
3141 that will accommodate request
3142 */
3143
3144
3145 #if __STD_C
pvALLOc(size_t bytes)3146 Void_t* pvALLOc(size_t bytes)
3147 #else
3148 Void_t* pvALLOc(bytes) RDECL size_t bytes;
3149 #endif
3150 {
3151 size_t pagesize = malloc_getpagesize;
3152 if (bytes > __SIZE_MAX__ - pagesize)
3153 {
3154 errno = ENOMEM;
3155 return 0;
3156 }
3157 return mEMALIGn (pagesize, (bytes + pagesize - 1) & ~(pagesize - 1));
3158 }
3159
3160 #endif /* DEFINE_PVALLOC */
3161
3162 #ifdef DEFINE_CALLOC
3163 #include "mul_overflow.h"
3164 /*
3165
3166 calloc calls malloc, then zeroes out the allocated chunk.
3167
3168 */
3169
3170 #if __STD_C
cALLOc(size_t n,size_t elem_size)3171 Void_t* cALLOc(size_t n, size_t elem_size)
3172 #else
3173 Void_t* cALLOc(n, elem_size) RDECL size_t n; size_t elem_size;
3174 #endif
3175 {
3176 mchunkptr p;
3177 INTERNAL_SIZE_T csz;
3178
3179 INTERNAL_SIZE_T sz;
3180
3181 #if MORECORE_CLEARS
3182 mchunkptr oldtop;
3183 INTERNAL_SIZE_T oldtopsize;
3184 #endif
3185 Void_t* mem;
3186
3187 if (mul_overflow((INTERNAL_SIZE_T) n, (INTERNAL_SIZE_T) elem_size, &sz))
3188 {
3189 errno = ENOMEM;
3190 return 0;
3191 }
3192
3193 /* check if expand_top called, in which case don't need to clear */
3194 #if MORECORE_CLEARS
3195 MALLOC_LOCK;
3196 oldtop = top;
3197 oldtopsize = chunksize(top);
3198 #endif
3199
3200 mem = mALLOc (sz);
3201
3202 if (mem == 0)
3203 {
3204 #if MORECORE_CLEARS
3205 MALLOC_UNLOCK;
3206 #endif
3207 return 0;
3208 }
3209 else
3210 {
3211 p = mem2chunk(mem);
3212
3213 /* Two optional cases in which clearing not necessary */
3214
3215
3216 #if HAVE_MMAP
3217 if (chunk_is_mmapped(p))
3218 {
3219 #if MORECORE_CLEARS
3220 MALLOC_UNLOCK;
3221 #endif
3222 return mem;
3223 }
3224 #endif
3225
3226 csz = chunksize(p);
3227
3228 #if MORECORE_CLEARS
3229 if (p == oldtop && csz > oldtopsize)
3230 {
3231 /* clear only the bytes from non-freshly-sbrked memory */
3232 csz = oldtopsize;
3233 }
3234 MALLOC_UNLOCK;
3235 #endif
3236
3237 MALLOC_ZERO(mem, csz - SIZE_SZ);
3238 return mem;
3239 }
3240 }
3241
3242 #endif /* DEFINE_CALLOC */
3243
3244 #if defined(DEFINE_CFREE) && !defined(__CYGWIN__)
3245
3246 /*
3247
3248 cfree just calls free. It is needed/defined on some systems
3249 that pair it with calloc, presumably for odd historical reasons.
3250
3251 */
3252
3253 #if !defined(INTERNAL_LINUX_C_LIB) || !defined(__ELF__)
3254 #if !defined(_LIBC) || !defined(_REENT_ONLY)
3255 #if __STD_C
cfree(Void_t * mem)3256 void cfree(Void_t *mem)
3257 #else
3258 void cfree(mem) Void_t *mem;
3259 #endif
3260 {
3261 fREe(mem);
3262 }
3263 #endif
3264 #endif
3265
3266 #endif /* DEFINE_CFREE */
3267
3268 #ifdef DEFINE_FREE
3269
3270 /*
3271
3272 Malloc_trim gives memory back to the system (via negative
3273 arguments to sbrk) if there is unused memory at the `high' end of
3274 the malloc pool. You can call this after freeing large blocks of
3275 memory to potentially reduce the system-level memory requirements
3276 of a program. However, it cannot guarantee to reduce memory. Under
3277 some allocation patterns, some large free blocks of memory will be
3278 locked between two used chunks, so they cannot be given back to
3279 the system.
3280
3281 The `pad' argument to malloc_trim represents the amount of free
3282 trailing space to leave untrimmed. If this argument is zero,
3283 only the minimum amount of memory to maintain internal data
3284 structures will be left (one page or less). Non-zero arguments
3285 can be supplied to maintain enough trailing space to service
3286 future expected allocations without having to re-obtain memory
3287 from the system.
3288
3289 Malloc_trim returns 1 if it actually released any memory, else 0.
3290
3291 */
3292
3293 #if __STD_C
malloc_trim(size_t pad)3294 int malloc_trim(size_t pad)
3295 #else
3296 int malloc_trim(pad) RDECL size_t pad;
3297 #endif
3298 {
3299 long top_size; /* Amount of top-most memory */
3300 long extra; /* Amount to release */
3301 char* current_brk; /* address returned by pre-check sbrk call */
3302 char* new_brk; /* address returned by negative sbrk call */
3303
3304 unsigned long pagesz = malloc_getpagesize;
3305
3306 MALLOC_LOCK;
3307
3308 top_size = chunksize(top);
3309 extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz;
3310
3311 if (extra < (long)pagesz) /* Not enough memory to release */
3312 {
3313 MALLOC_UNLOCK;
3314 return 0;
3315 }
3316
3317 else
3318 {
3319 /* Test to make sure no one else called sbrk */
3320 current_brk = (char*)(MORECORE (0));
3321 if (current_brk != (char*)(top) + top_size)
3322 {
3323 MALLOC_UNLOCK;
3324 return 0; /* Apparently we don't own memory; must fail */
3325 }
3326
3327 else
3328 {
3329 new_brk = (char*)(MORECORE (-extra));
3330
3331 if (new_brk == (char*)(MORECORE_FAILURE)) /* sbrk failed? */
3332 {
3333 /* Try to figure out what we have */
3334 current_brk = (char*)(MORECORE (0));
3335 top_size = current_brk - (char*)top;
3336 if (top_size >= (long)MINSIZE) /* if not, we are very very dead! */
3337 {
3338 sbrked_mem = current_brk - sbrk_base;
3339 set_head(top, top_size | PREV_INUSE);
3340 }
3341 check_chunk(top);
3342 MALLOC_UNLOCK;
3343 return 0;
3344 }
3345
3346 else
3347 {
3348 /* Success. Adjust top accordingly. */
3349 set_head(top, (top_size - extra) | PREV_INUSE);
3350 sbrked_mem -= extra;
3351 check_chunk(top);
3352 MALLOC_UNLOCK;
3353 return 1;
3354 }
3355 }
3356 }
3357 }
3358
3359 #endif /* DEFINE_FREE */
3360
3361 #ifdef DEFINE_MALLOC_USABLE_SIZE
3362
3363 /*
3364 malloc_usable_size:
3365
3366 This routine tells you how many bytes you can actually use in an
3367 allocated chunk, which may be more than you requested (although
3368 often not). You can use this many bytes without worrying about
3369 overwriting other allocated objects. Not a particularly great
3370 programming practice, but still sometimes useful.
3371
3372 */
3373
3374 #if __STD_C
malloc_usable_size(Void_t * mem)3375 size_t malloc_usable_size(Void_t* mem)
3376 #else
3377 size_t malloc_usable_size(mem) RDECL Void_t* mem;
3378 #endif
3379 {
3380 mchunkptr p;
3381 if (mem == 0)
3382 return 0;
3383 else
3384 {
3385 p = mem2chunk(mem);
3386 if(!chunk_is_mmapped(p))
3387 {
3388 if (!inuse(p)) return 0;
3389 #if DEBUG
3390 MALLOC_LOCK;
3391 check_inuse_chunk(p);
3392 MALLOC_UNLOCK;
3393 #endif
3394 return chunksize(p) - SIZE_SZ;
3395 }
3396 return chunksize(p) - 2*SIZE_SZ;
3397 }
3398 }
3399
3400 #endif /* DEFINE_MALLOC_USABLE_SIZE */
3401
3402 #ifdef DEFINE_MALLINFO
3403
3404 /* Utility to update current_mallinfo for malloc_stats and mallinfo() */
3405
malloc_update_mallinfo(void)3406 STATIC void malloc_update_mallinfo(void)
3407 {
3408 int i;
3409 mbinptr b;
3410 mchunkptr p;
3411 #if DEBUG
3412 mchunkptr q;
3413 #endif
3414
3415 INTERNAL_SIZE_T avail = chunksize(top);
3416 int navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0;
3417
3418 for (i = 1; i < NAV; ++i)
3419 {
3420 b = bin_at(i);
3421 for (p = last(b); p != b; p = p->bk)
3422 {
3423 #if DEBUG
3424 check_free_chunk(p);
3425 for (q = next_chunk(p);
3426 q < top && inuse(q) && (long)(chunksize(q)) >= (long)MINSIZE;
3427 q = next_chunk(q))
3428 check_inuse_chunk(q);
3429 #endif
3430 avail += chunksize(p);
3431 navail++;
3432 }
3433 }
3434
3435 current_mallinfo.ordblks = navail;
3436 current_mallinfo.uordblks = sbrked_mem - avail;
3437 current_mallinfo.fordblks = avail;
3438 #if HAVE_MMAP
3439 current_mallinfo.hblks = n_mmaps;
3440 current_mallinfo.hblkhd = mmapped_mem;
3441 #endif
3442 current_mallinfo.keepcost = chunksize(top);
3443
3444 }
3445
3446 #else /* ! DEFINE_MALLINFO */
3447
3448 #if __STD_C
3449 extern void malloc_update_mallinfo(void);
3450 #else
3451 extern void malloc_update_mallinfo();
3452 #endif
3453
3454 #endif /* ! DEFINE_MALLINFO */
3455
3456 #ifdef DEFINE_MALLOC_STATS
3457
3458 /*
3459
3460 malloc_stats:
3461
3462 Prints on stderr the amount of space obtain from the system (both
3463 via sbrk and mmap), the maximum amount (which may be more than
3464 current if malloc_trim and/or munmap got called), the maximum
3465 number of simultaneous mmap regions used, and the current number
3466 of bytes allocated via malloc (or realloc, etc) but not yet
3467 freed. (Note that this is the number of bytes allocated, not the
3468 number requested. It will be larger than the number requested
3469 because of alignment and bookkeeping overhead.)
3470
3471 */
3472
3473 #if __STD_C
malloc_stats(void)3474 void malloc_stats(void)
3475 #else
3476 void malloc_stats() RDECL
3477 #endif
3478 {
3479 unsigned long local_max_total_mem;
3480 int local_sbrked_mem;
3481 struct mallinfo local_mallinfo;
3482 #if HAVE_MMAP
3483 unsigned long local_mmapped_mem, local_max_n_mmaps;
3484 #endif
3485 FILE *fp;
3486
3487 MALLOC_LOCK;
3488 malloc_update_mallinfo();
3489 local_max_total_mem = max_total_mem;
3490 local_sbrked_mem = sbrked_mem;
3491 local_mallinfo = current_mallinfo;
3492 #if HAVE_MMAP
3493 local_mmapped_mem = mmapped_mem;
3494 local_max_n_mmaps = max_n_mmaps;
3495 #endif
3496 MALLOC_UNLOCK;
3497
3498 fp = stderr;
3499
3500 fprintf(fp, "max system bytes = %10u\n",
3501 (unsigned int)(local_max_total_mem));
3502 #if HAVE_MMAP
3503 fprintf(fp, "system bytes = %10u\n",
3504 (unsigned int)(local_sbrked_mem + local_mmapped_mem));
3505 fprintf(fp, "in use bytes = %10u\n",
3506 (unsigned int)(local_mallinfo.uordblks + local_mmapped_mem));
3507 #else
3508 fprintf(fp, "system bytes = %10u\n",
3509 (unsigned int)local_sbrked_mem);
3510 fprintf(fp, "in use bytes = %10u\n",
3511 (unsigned int)local_mallinfo.uordblks);
3512 #endif
3513 #if HAVE_MMAP
3514 fprintf(fp, "max mmap regions = %10u\n",
3515 (unsigned int)local_max_n_mmaps);
3516 #endif
3517 }
3518
3519 #endif /* DEFINE_MALLOC_STATS */
3520
3521 #ifdef DEFINE_MALLINFO
3522
3523 /*
3524 mallinfo returns a copy of updated current mallinfo.
3525 */
3526
3527 #if __STD_C
mALLINFo(void)3528 struct mallinfo mALLINFo(void)
3529 #else
3530 struct mallinfo mALLINFo() RDECL
3531 #endif
3532 {
3533 struct mallinfo ret;
3534
3535 MALLOC_LOCK;
3536 malloc_update_mallinfo();
3537 ret = current_mallinfo;
3538 MALLOC_UNLOCK;
3539 return ret;
3540 }
3541
3542 #endif /* DEFINE_MALLINFO */
3543
3544 #ifdef DEFINE_MALLOPT
3545
3546 /*
3547 mallopt:
3548
3549 mallopt is the general SVID/XPG interface to tunable parameters.
3550 The format is to provide a (parameter-number, parameter-value) pair.
3551 mallopt then sets the corresponding parameter to the argument
3552 value if it can (i.e., so long as the value is meaningful),
3553 and returns 1 if successful else 0.
3554
3555 See descriptions of tunable parameters above.
3556
3557 */
3558
3559 #if __STD_C
mALLOPt(int param_number,int value)3560 int mALLOPt(int param_number, int value)
3561 #else
3562 int mALLOPt(param_number, value) RDECL int param_number; int value;
3563 #endif
3564 {
3565 MALLOC_LOCK;
3566 switch(param_number)
3567 {
3568 case M_TRIM_THRESHOLD:
3569 trim_threshold = value; MALLOC_UNLOCK; return 1;
3570 case M_TOP_PAD:
3571 top_pad = value; MALLOC_UNLOCK; return 1;
3572 case M_MMAP_THRESHOLD:
3573 #if HAVE_MMAP
3574 mmap_threshold = value;
3575 #endif
3576 MALLOC_UNLOCK;
3577 return 1;
3578 case M_MMAP_MAX:
3579 #if HAVE_MMAP
3580 n_mmaps_max = value; MALLOC_UNLOCK; return 1;
3581 #else
3582 MALLOC_UNLOCK; return value == 0;
3583 #endif
3584
3585 default:
3586 MALLOC_UNLOCK;
3587 return 0;
3588 }
3589 }
3590
3591 #endif /* DEFINE_MALLOPT */
3592
3593 /*
3594
3595 History:
3596
3597 V2.6.5 Wed Jun 17 15:57:31 1998 Doug Lea (dl at gee)
3598 * Fixed ordering problem with boundary-stamping
3599
3600 V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee)
3601 * Added pvalloc, as recommended by H.J. Liu
3602 * Added 64bit pointer support mainly from Wolfram Gloger
3603 * Added anonymously donated WIN32 sbrk emulation
3604 * Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen
3605 * malloc_extend_top: fix mask error that caused wastage after
3606 foreign sbrks
3607 * Add linux mremap support code from HJ Liu
3608
3609 V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee)
3610 * Integrated most documentation with the code.
3611 * Add support for mmap, with help from
3612 Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
3613 * Use last_remainder in more cases.
3614 * Pack bins using idea from colin@nyx10.cs.du.edu
3615 * Use ordered bins instead of best-fit threshhold
3616 * Eliminate block-local decls to simplify tracing and debugging.
3617 * Support another case of realloc via move into top
3618 * Fix error occuring when initial sbrk_base not word-aligned.
3619 * Rely on page size for units instead of SBRK_UNIT to
3620 avoid surprises about sbrk alignment conventions.
3621 * Add mallinfo, mallopt. Thanks to Raymond Nijssen
3622 (raymond@es.ele.tue.nl) for the suggestion.
3623 * Add `pad' argument to malloc_trim and top_pad mallopt parameter.
3624 * More precautions for cases where other routines call sbrk,
3625 courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
3626 * Added macros etc., allowing use in linux libc from
3627 H.J. Lu (hjl@gnu.ai.mit.edu)
3628 * Inverted this history list
3629
3630 V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee)
3631 * Re-tuned and fixed to behave more nicely with V2.6.0 changes.
3632 * Removed all preallocation code since under current scheme
3633 the work required to undo bad preallocations exceeds
3634 the work saved in good cases for most test programs.
3635 * No longer use return list or unconsolidated bins since
3636 no scheme using them consistently outperforms those that don't
3637 given above changes.
3638 * Use best fit for very large chunks to prevent some worst-cases.
3639 * Added some support for debugging
3640
3641 V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee)
3642 * Removed footers when chunks are in use. Thanks to
3643 Paul Wilson (wilson@cs.texas.edu) for the suggestion.
3644
3645 V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee)
3646 * Added malloc_trim, with help from Wolfram Gloger
3647 (wmglo@Dent.MED.Uni-Muenchen.DE).
3648
3649 V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g)
3650
3651 V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g)
3652 * realloc: try to expand in both directions
3653 * malloc: swap order of clean-bin strategy;
3654 * realloc: only conditionally expand backwards
3655 * Try not to scavenge used bins
3656 * Use bin counts as a guide to preallocation
3657 * Occasionally bin return list chunks in first scan
3658 * Add a few optimizations from colin@nyx10.cs.du.edu
3659
3660 V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g)
3661 * faster bin computation & slightly different binning
3662 * merged all consolidations to one part of malloc proper
3663 (eliminating old malloc_find_space & malloc_clean_bin)
3664 * Scan 2 returns chunks (not just 1)
3665 * Propagate failure in realloc if malloc returns 0
3666 * Add stuff to allow compilation on non-ANSI compilers
3667 from kpv@research.att.com
3668
3669 V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu)
3670 * removed potential for odd address access in prev_chunk
3671 * removed dependency on getpagesize.h
3672 * misc cosmetics and a bit more internal documentation
3673 * anticosmetics: mangled names in macros to evade debugger strangeness
3674 * tested on sparc, hp-700, dec-mips, rs6000
3675 with gcc & native cc (hp, dec only) allowing
3676 Detlefs & Zorn comparison study (in SIGPLAN Notices.)
3677
3678 Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu)
3679 * Based loosely on libg++-1.2X malloc. (It retains some of the overall
3680 structure of old version, but most details differ.)
3681
3682 */
3683 #endif
3684
