malloc.h
32.9 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
/*
A version of malloc/free/realloc written by Doug Lea and released to the
public domain. Send questions/comments/complaints/performance data
to dl@cs.oswego.edu
* VERSION 2.6.6 Sun Mar 5 19:10:03 2000 Doug Lea (dl at gee)
Note: There may be an updated version of this malloc obtainable at
ftp://g.oswego.edu/pub/misc/malloc.c
Check before installing!
* Why use this malloc?
This is not the fastest, most space-conserving, most portable, or
most tunable malloc ever written. However it is among the fastest
while also being among the most space-conserving, portable and tunable.
Consistent balance across these factors results in a good general-purpose
allocator. For a high-level description, see
http://g.oswego.edu/dl/html/malloc.html
* Synopsis of public routines
(Much fuller descriptions are contained in the program documentation below.)
malloc(size_t n);
Return a pointer to a newly allocated chunk of at least n bytes, or null
if no space is available.
free(Void_t* p);
Release the chunk of memory pointed to by p, or no effect if p is null.
realloc(Void_t* p, size_t n);
Return a pointer to a chunk of size n that contains the same data
as does chunk p up to the minimum of (n, p's size) bytes, or null
if no space is available. The returned pointer may or may not be
the same as p. If p is null, equivalent to malloc. Unless the
#define REALLOC_ZERO_BYTES_FREES below is set, realloc with a
size argument of zero (re)allocates a minimum-sized chunk.
memalign(size_t alignment, size_t n);
Return a pointer to a newly allocated chunk of n bytes, aligned
in accord with the alignment argument, which must be a power of
two.
valloc(size_t n);
Equivalent to memalign(pagesize, n), where pagesize is the page
size of the system (or as near to this as can be figured out from
all the includes/defines below.)
pvalloc(size_t n);
Equivalent to valloc(minimum-page-that-holds(n)), that is,
round up n to nearest pagesize.
calloc(size_t unit, size_t quantity);
Returns a pointer to quantity * unit bytes, with all locations
set to zero.
cfree(Void_t* p);
Equivalent to free(p).
malloc_trim(size_t pad);
Release all but pad bytes of freed top-most memory back
to the system. Return 1 if successful, else 0.
malloc_usable_size(Void_t* p);
Report the number usable allocated bytes associated with allocated
chunk p. This may or may not report more bytes than were requested,
due to alignment and minimum size constraints.
malloc_stats();
Prints brief summary statistics on stderr.
mallinfo()
Returns (by copy) a struct containing various summary statistics.
mallopt(int parameter_number, int parameter_value)
Changes one of the tunable parameters described below. Returns
1 if successful in changing the parameter, else 0.
* Vital statistics:
Alignment: 8-byte
8 byte alignment is currently hardwired into the design. This
seems to suffice for all current machines and C compilers.
Assumed pointer representation: 4 or 8 bytes
Code for 8-byte pointers is untested by me but has worked
reliably by Wolfram Gloger, who contributed most of the
changes supporting this.
Assumed size_t representation: 4 or 8 bytes
Note that size_t is allowed to be 4 bytes even if pointers are 8.
Minimum overhead per allocated chunk: 4 or 8 bytes
Each malloced chunk has a hidden overhead of 4 bytes holding size
and status information.
Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
needed; 4 (8) for a trailing size field
and 8 (16) bytes for free list pointers. Thus, the minimum
allocatable size is 16/24/32 bytes.
Even a request for zero bytes (i.e., malloc(0)) returns a
pointer to something of the minimum allocatable size.
Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes
8-byte size_t: 2^63 - 16 bytes
It is assumed that (possibly signed) size_t bit values suffice to
represent chunk sizes. `Possibly signed' is due to the fact
that `size_t' may be defined on a system as either a signed or
an unsigned type. To be conservative, values that would appear
as negative numbers are avoided.
Requests for sizes with a negative sign bit when the request
size is treaded as a long will return null.
Maximum overhead wastage per allocated chunk: normally 15 bytes
Alignnment demands, plus the minimum allocatable size restriction
make the normal worst-case wastage 15 bytes (i.e., up to 15
more bytes will be allocated than were requested in malloc), with
two exceptions:
1. Because requests for zero bytes allocate non-zero space,
the worst case wastage for a request of zero bytes is 24 bytes.
2. For requests >= mmap_threshold that are serviced via
mmap(), the worst case wastage is 8 bytes plus the remainder
from a system page (the minimal mmap unit); typically 4096 bytes.
* Limitations
Here are some features that are NOT currently supported
* No user-definable hooks for callbacks and the like.
* No automated mechanism for fully checking that all accesses
to malloced memory stay within their bounds.
* No support for compaction.
* Synopsis of compile-time options:
People have reported using previous versions of this malloc on all
versions of Unix, sometimes by tweaking some of the defines
below. It has been tested most extensively on Solaris and
Linux. It is also reported to work on WIN32 platforms.
People have also reported adapting this malloc for use in
stand-alone embedded systems.
The implementation is in straight, hand-tuned ANSI C. Among other
consequences, it uses a lot of macros. Because of this, to be at
all usable, this code should be compiled using an optimizing compiler
(for example gcc -O2) that can simplify expressions and control
paths.
__STD_C (default: derived from C compiler defines)
Nonzero if using ANSI-standard C compiler, a C++ compiler, or
a C compiler sufficiently close to ANSI to get away with it.
DEBUG (default: NOT defined)
Define to enable debugging. Adds fairly extensive assertion-based
checking to help track down memory errors, but noticeably slows down
execution.
REALLOC_ZERO_BYTES_FREES (default: NOT defined)
Define this if you think that realloc(p, 0) should be equivalent
to free(p). Otherwise, since malloc returns a unique pointer for
malloc(0), so does realloc(p, 0).
HAVE_MEMCPY (default: defined)
Define if you are not otherwise using ANSI STD C, but still
have memcpy and memset in your C library and want to use them.
Otherwise, simple internal versions are supplied.
USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)
Define as 1 if you want the C library versions of memset and
memcpy called in realloc and calloc (otherwise macro versions are used).
At least on some platforms, the simple macro versions usually
outperform libc versions.
HAVE_MMAP (default: defined as 1)
Define to non-zero to optionally make malloc() use mmap() to
allocate very large blocks.
HAVE_MREMAP (default: defined as 0 unless Linux libc set)
Define to non-zero to optionally make realloc() use mremap() to
reallocate very large blocks.
malloc_getpagesize (default: derived from system #includes)
Either a constant or routine call returning the system page size.
HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)
Optionally define if you are on a system with a /usr/include/malloc.h
that declares struct mallinfo. It is not at all necessary to
define this even if you do, but will ensure consistency.
INTERNAL_SIZE_T (default: size_t)
Define to a 32-bit type (probably `unsigned int') if you are on a
64-bit machine, yet do not want or need to allow malloc requests of
greater than 2^31 to be handled. This saves space, especially for
very small chunks.
INTERNAL_LINUX_C_LIB (default: NOT defined)
Defined only when compiled as part of Linux libc.
Also note that there is some odd internal name-mangling via defines
(for example, internally, `malloc' is named `mALLOc') needed
when compiling in this case. These look funny but don't otherwise
affect anything.
WIN32 (default: undefined)
Define this on MS win (95, nt) platforms to compile in sbrk emulation.
LACKS_UNISTD_H (default: undefined if not WIN32)
Define this if your system does not have a <unistd.h>.
LACKS_SYS_PARAM_H (default: undefined if not WIN32)
Define this if your system does not have a <sys/param.h>.
MORECORE (default: sbrk)
The name of the routine to call to obtain more memory from the system.
MORECORE_FAILURE (default: -1)
The value returned upon failure of MORECORE.
MORECORE_CLEARS (default 1)
True (1) if the routine mapped to MORECORE zeroes out memory (which
holds for sbrk).
DEFAULT_TRIM_THRESHOLD
DEFAULT_TOP_PAD
DEFAULT_MMAP_THRESHOLD
DEFAULT_MMAP_MAX
Default values of tunable parameters (described in detail below)
controlling interaction with host system routines (sbrk, mmap, etc).
These values may also be changed dynamically via mallopt(). The
preset defaults are those that give best performance for typical
programs/systems.
USE_DL_PREFIX (default: undefined)
Prefix all public routines with the string 'dl'. Useful to
quickly avoid procedure declaration conflicts and linker symbol
conflicts with existing memory allocation routines.
*/
/* Preliminaries */
#ifndef __STD_C
#ifdef __STDC__
#define __STD_C 1
#else
#if __cplusplus
#define __STD_C 1
#else
#define __STD_C 0
#endif /*__cplusplus*/
#endif /*__STDC__*/
#endif /*__STD_C*/
#ifndef Void_t
#if (__STD_C || defined(WIN32))
#define Void_t void
#else
#define Void_t char
#endif
#endif /*Void_t*/
#if __STD_C
#include <linux/stddef.h> /* for size_t */
#else
#include <sys/types.h>
#endif /* __STD_C */
#ifdef __cplusplus
extern "C" {
#endif
#if 0 /* not for U-Boot */
#include <stdio.h> /* needed for malloc_stats */
#endif
/*
Compile-time options
*/
/*
Debugging:
Because freed chunks may be overwritten with link fields, this
malloc will often die when freed memory is overwritten by user
programs. This can be very effective (albeit in an annoying way)
in helping track down dangling pointers.
If you compile with -DDEBUG, a number of assertion checks are
enabled that will catch more memory errors. You probably won't be
able to make much sense of the actual assertion errors, but they
should help you locate incorrectly overwritten memory. The
checking is fairly extensive, and will slow down execution
noticeably. Calling malloc_stats or mallinfo with DEBUG set will
attempt to check every non-mmapped allocated and free chunk in the
course of computing the summmaries. (By nature, mmapped regions
cannot be checked very much automatically.)
Setting DEBUG may also be helpful if you are trying to modify
this code. The assertions in the check routines spell out in more
detail the assumptions and invariants underlying the algorithms.
*/
#ifdef DEBUG
/* #include <assert.h> */
#define assert(x) ((void)0)
#else
#define assert(x) ((void)0)
#endif
/*
INTERNAL_SIZE_T is the word-size used for internal bookkeeping
of chunk sizes. On a 64-bit machine, you can reduce malloc
overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'
at the expense of not being able to handle requests greater than
2^31. This limitation is hardly ever a concern; you are encouraged
to set this. However, the default version is the same as size_t.
*/
#ifndef INTERNAL_SIZE_T
#define INTERNAL_SIZE_T size_t
#endif
/*
REALLOC_ZERO_BYTES_FREES should be set if a call to
realloc with zero bytes should be the same as a call to free.
Some people think it should. Otherwise, since this malloc
returns a unique pointer for malloc(0), so does realloc(p, 0).
*/
/* #define REALLOC_ZERO_BYTES_FREES */
/*
WIN32 causes an emulation of sbrk to be compiled in
mmap-based options are not currently supported in WIN32.
*/
/* #define WIN32 */
#ifdef WIN32
#define MORECORE wsbrk
#define HAVE_MMAP 0
#define LACKS_UNISTD_H
#define LACKS_SYS_PARAM_H
/*
Include 'windows.h' to get the necessary declarations for the
Microsoft Visual C++ data structures and routines used in the 'sbrk'
emulation.
Define WIN32_LEAN_AND_MEAN so that only the essential Microsoft
Visual C++ header files are included.
*/
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#endif
/*
HAVE_MEMCPY should be defined if you are not otherwise using
ANSI STD C, but still have memcpy and memset in your C library
and want to use them in calloc and realloc. Otherwise simple
macro versions are defined here.
USE_MEMCPY should be defined as 1 if you actually want to
have memset and memcpy called. People report that the macro
versions are often enough faster than libc versions on many
systems that it is better to use them.
*/
#define HAVE_MEMCPY
#ifndef USE_MEMCPY
#ifdef HAVE_MEMCPY
#define USE_MEMCPY 1
#else
#define USE_MEMCPY 0
#endif
#endif
#if (__STD_C || defined(HAVE_MEMCPY))
#if __STD_C
void* memset(void*, int, size_t);
void* memcpy(void*, const void*, size_t);
#else
#ifdef WIN32
/* On Win32 platforms, 'memset()' and 'memcpy()' are already declared in */
/* 'windows.h' */
#else
Void_t* memset();
Void_t* memcpy();
#endif
#endif
#endif
#if USE_MEMCPY
/* The following macros are only invoked with (2n+1)-multiples of
INTERNAL_SIZE_T units, with a positive integer n. This is exploited
for fast inline execution when n is small. */
#define MALLOC_ZERO(charp, nbytes) \
do { \
INTERNAL_SIZE_T mzsz = (nbytes); \
if(mzsz <= 9*sizeof(mzsz)) { \
INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \
if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \
*mz++ = 0; \
if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \
*mz++ = 0; \
if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \
*mz++ = 0; }}} \
*mz++ = 0; \
*mz++ = 0; \
*mz = 0; \
} else memset((charp), 0, mzsz); \
} while(0)
#define MALLOC_COPY(dest,src,nbytes) \
do { \
INTERNAL_SIZE_T mcsz = (nbytes); \
if(mcsz <= 9*sizeof(mcsz)) { \
INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \
INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \
if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; \
if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; \
if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; }}} \
*mcdst++ = *mcsrc++; \
*mcdst++ = *mcsrc++; \
*mcdst = *mcsrc ; \
} else memcpy(dest, src, mcsz); \
} while(0)
#else /* !USE_MEMCPY */
/* Use Duff's device for good zeroing/copying performance. */
#define MALLOC_ZERO(charp, nbytes) \
do { \
INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \
long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
switch (mctmp) { \
case 0: for(;;) { *mzp++ = 0; \
case 7: *mzp++ = 0; \
case 6: *mzp++ = 0; \
case 5: *mzp++ = 0; \
case 4: *mzp++ = 0; \
case 3: *mzp++ = 0; \
case 2: *mzp++ = 0; \
case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \
} \
} while(0)
#define MALLOC_COPY(dest,src,nbytes) \
do { \
INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \
INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \
long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
switch (mctmp) { \
case 0: for(;;) { *mcdst++ = *mcsrc++; \
case 7: *mcdst++ = *mcsrc++; \
case 6: *mcdst++ = *mcsrc++; \
case 5: *mcdst++ = *mcsrc++; \
case 4: *mcdst++ = *mcsrc++; \
case 3: *mcdst++ = *mcsrc++; \
case 2: *mcdst++ = *mcsrc++; \
case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \
} \
} while(0)
#endif
/*
Define HAVE_MMAP to optionally make malloc() use mmap() to
allocate very large blocks. These will be returned to the
operating system immediately after a free().
*/
/***
#ifndef HAVE_MMAP
#define HAVE_MMAP 1
#endif
***/
#undef HAVE_MMAP /* Not available for U-Boot */
/*
Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
large blocks. This is currently only possible on Linux with
kernel versions newer than 1.3.77.
*/
/***
#ifndef HAVE_MREMAP
#ifdef INTERNAL_LINUX_C_LIB
#define HAVE_MREMAP 1
#else
#define HAVE_MREMAP 0
#endif
#endif
***/
#undef HAVE_MREMAP /* Not available for U-Boot */
#if HAVE_MMAP
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
#define MAP_ANONYMOUS MAP_ANON
#endif
#endif /* HAVE_MMAP */
/*
Access to system page size. To the extent possible, this malloc
manages memory from the system in page-size units.
The following mechanics for getpagesize were adapted from
bsd/gnu getpagesize.h
*/
#define LACKS_UNISTD_H /* Shortcut for U-Boot */
#define malloc_getpagesize 4096
#ifndef LACKS_UNISTD_H
# include <unistd.h>
#endif
#ifndef malloc_getpagesize
# ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
# ifndef _SC_PAGE_SIZE
# define _SC_PAGE_SIZE _SC_PAGESIZE
# endif
# endif
# ifdef _SC_PAGE_SIZE
# define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
# else
# if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
extern size_t getpagesize();
# define malloc_getpagesize getpagesize()
# else
# ifdef WIN32
# define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */
# else
# ifndef LACKS_SYS_PARAM_H
# include <sys/param.h>
# endif
# ifdef EXEC_PAGESIZE
# define malloc_getpagesize EXEC_PAGESIZE
# else
# ifdef NBPG
# ifndef CLSIZE
# define malloc_getpagesize NBPG
# else
# define malloc_getpagesize (NBPG * CLSIZE)
# endif
# else
# ifdef NBPC
# define malloc_getpagesize NBPC
# else
# ifdef PAGESIZE
# define malloc_getpagesize PAGESIZE
# else
# define malloc_getpagesize (4096) /* just guess */
# endif
# endif
# endif
# endif
# endif
# endif
# endif
#endif
/*
This version of malloc supports the standard SVID/XPG mallinfo
routine that returns a struct containing the same kind of
information you can get from malloc_stats. It should work on
any SVID/XPG compliant system that has a /usr/include/malloc.h
defining struct mallinfo. (If you'd like to install such a thing
yourself, cut out the preliminary declarations as described above
and below and save them in a malloc.h file. But there's no
compelling reason to bother to do this.)
The main declaration needed is the mallinfo struct that is returned
(by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
bunch of fields, most of which are not even meaningful in this
version of malloc. Some of these fields are are instead filled by
mallinfo() with other numbers that might possibly be of interest.
HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
/usr/include/malloc.h file that includes a declaration of struct
mallinfo. If so, it is included; else an SVID2/XPG2 compliant
version is declared below. These must be precisely the same for
mallinfo() to work.
*/
/* #define HAVE_USR_INCLUDE_MALLOC_H */
#if HAVE_USR_INCLUDE_MALLOC_H
#include "/usr/include/malloc.h"
#else
/* SVID2/XPG mallinfo structure */
struct mallinfo {
int arena; /* total space allocated from system */
int ordblks; /* number of non-inuse chunks */
int smblks; /* unused -- always zero */
int hblks; /* number of mmapped regions */
int hblkhd; /* total space in mmapped regions */
int usmblks; /* unused -- always zero */
int fsmblks; /* unused -- always zero */
int uordblks; /* total allocated space */
int fordblks; /* total non-inuse space */
int keepcost; /* top-most, releasable (via malloc_trim) space */
};
/* SVID2/XPG mallopt options */
#define M_MXFAST 1 /* UNUSED in this malloc */
#define M_NLBLKS 2 /* UNUSED in this malloc */
#define M_GRAIN 3 /* UNUSED in this malloc */
#define M_KEEP 4 /* UNUSED in this malloc */
#endif
/* mallopt options that actually do something */
#define M_TRIM_THRESHOLD -1
#define M_TOP_PAD -2
#define M_MMAP_THRESHOLD -3
#define M_MMAP_MAX -4
#ifndef DEFAULT_TRIM_THRESHOLD
#define DEFAULT_TRIM_THRESHOLD (128 * 1024)
#endif
/*
M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
to keep before releasing via malloc_trim in free().
Automatic trimming is mainly useful in long-lived programs.
Because trimming via sbrk can be slow on some systems, and can
sometimes be wasteful (in cases where programs immediately
afterward allocate more large chunks) the value should be high
enough so that your overall system performance would improve by
releasing.
The trim threshold and the mmap control parameters (see below)
can be traded off with one another. Trimming and mmapping are
two different ways of releasing unused memory back to the
system. Between these two, it is often possible to keep
system-level demands of a long-lived program down to a bare
minimum. For example, in one test suite of sessions measuring
the XF86 X server on Linux, using a trim threshold of 128K and a
mmap threshold of 192K led to near-minimal long term resource
consumption.
If you are using this malloc in a long-lived program, it should
pay to experiment with these values. As a rough guide, you
might set to a value close to the average size of a process
(program) running on your system. Releasing this much memory
would allow such a process to run in memory. Generally, it's
worth it to tune for trimming rather tham memory mapping when a
program undergoes phases where several large chunks are
allocated and released in ways that can reuse each other's
storage, perhaps mixed with phases where there are no such
chunks at all. And in well-behaved long-lived programs,
controlling release of large blocks via trimming versus mapping
is usually faster.
However, in most programs, these parameters serve mainly as
protection against the system-level effects of carrying around
massive amounts of unneeded memory. Since frequent calls to
sbrk, mmap, and munmap otherwise degrade performance, the default
parameters are set to relatively high values that serve only as
safeguards.
The default trim value is high enough to cause trimming only in
fairly extreme (by current memory consumption standards) cases.
It must be greater than page size to have any useful effect. To
disable trimming completely, you can set to (unsigned long)(-1);
*/
#ifndef DEFAULT_TOP_PAD
#define DEFAULT_TOP_PAD (0)
#endif
/*
M_TOP_PAD is the amount of extra `padding' space to allocate or
retain whenever sbrk is called. It is used in two ways internally:
* When sbrk is called to extend the top of the arena to satisfy
a new malloc request, this much padding is added to the sbrk
request.
* When malloc_trim is called automatically from free(),
it is used as the `pad' argument.
In both cases, the actual amount of padding is rounded
so that the end of the arena is always a system page boundary.
The main reason for using padding is to avoid calling sbrk so
often. Having even a small pad greatly reduces the likelihood
that nearly every malloc request during program start-up (or
after trimming) will invoke sbrk, which needlessly wastes
time.
Automatic rounding-up to page-size units is normally sufficient
to avoid measurable overhead, so the default is 0. However, in
systems where sbrk is relatively slow, it can pay to increase
this value, at the expense of carrying around more memory than
the program needs.
*/
#ifndef DEFAULT_MMAP_THRESHOLD
#define DEFAULT_MMAP_THRESHOLD (128 * 1024)
#endif
/*
M_MMAP_THRESHOLD is the request size threshold for using mmap()
to service a request. Requests of at least this size that cannot
be allocated using already-existing space will be serviced via mmap.
(If enough normal freed space already exists it is used instead.)
Using mmap segregates relatively large chunks of memory so that
they can be individually obtained and released from the host
system. A request serviced through mmap is never reused by any
other request (at least not directly; the system may just so
happen to remap successive requests to the same locations).
Segregating space in this way has the benefit that mmapped space
can ALWAYS be individually released back to the system, which
helps keep the system level memory demands of a long-lived
program low. Mapped memory can never become `locked' between
other chunks, as can happen with normally allocated chunks, which
menas that even trimming via malloc_trim would not release them.
However, it has the disadvantages that:
1. The space cannot be reclaimed, consolidated, and then
used to service later requests, as happens with normal chunks.
2. It can lead to more wastage because of mmap page alignment
requirements
3. It causes malloc performance to be more dependent on host
system memory management support routines which may vary in
implementation quality and may impose arbitrary
limitations. Generally, servicing a request via normal
malloc steps is faster than going through a system's mmap.
All together, these considerations should lead you to use mmap
only for relatively large requests.
*/
#ifndef DEFAULT_MMAP_MAX
#if HAVE_MMAP
#define DEFAULT_MMAP_MAX (64)
#else
#define DEFAULT_MMAP_MAX (0)
#endif
#endif
/*
M_MMAP_MAX is the maximum number of requests to simultaneously
service using mmap. This parameter exists because:
1. Some systems have a limited number of internal tables for
use by mmap.
2. In most systems, overreliance on mmap can degrade overall
performance.
3. If a program allocates many large regions, it is probably
better off using normal sbrk-based allocation routines that
can reclaim and reallocate normal heap memory. Using a
small value allows transition into this mode after the
first few allocations.
Setting to 0 disables all use of mmap. If HAVE_MMAP is not set,
the default value is 0, and attempts to set it to non-zero values
in mallopt will fail.
*/
/*
USE_DL_PREFIX will prefix all public routines with the string 'dl'.
Useful to quickly avoid procedure declaration conflicts and linker
symbol conflicts with existing memory allocation routines.
*/
/* #define USE_DL_PREFIX */
/*
Special defines for linux libc
Except when compiled using these special defines for Linux libc
using weak aliases, this malloc is NOT designed to work in
multithreaded applications. No semaphores or other concurrency
control are provided to ensure that multiple malloc or free calls
don't run at the same time, which could be disasterous. A single
semaphore could be used across malloc, realloc, and free (which is
essentially the effect of the linux weak alias approach). It would
be hard to obtain finer granularity.
*/
#ifdef INTERNAL_LINUX_C_LIB
#if __STD_C
Void_t * __default_morecore_init (ptrdiff_t);
Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init;
#else
Void_t * __default_morecore_init ();
Void_t *(*__morecore)() = __default_morecore_init;
#endif
#define MORECORE (*__morecore)
#define MORECORE_FAILURE 0
#define MORECORE_CLEARS 1
#else /* INTERNAL_LINUX_C_LIB */
#if __STD_C
extern Void_t* sbrk(ptrdiff_t);
#else
extern Void_t* sbrk();
#endif
#ifndef MORECORE
#define MORECORE sbrk
#endif
#ifndef MORECORE_FAILURE
#define MORECORE_FAILURE -1
#endif
#ifndef MORECORE_CLEARS
#define MORECORE_CLEARS 1
#endif
#endif /* INTERNAL_LINUX_C_LIB */
#if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__)
#define cALLOc __libc_calloc
#define fREe __libc_free
#define mALLOc __libc_malloc
#define mEMALIGn __libc_memalign
#define rEALLOc __libc_realloc
#define vALLOc __libc_valloc
#define pvALLOc __libc_pvalloc
#define mALLINFo __libc_mallinfo
#define mALLOPt __libc_mallopt
#pragma weak calloc = __libc_calloc
#pragma weak free = __libc_free
#pragma weak cfree = __libc_free
#pragma weak malloc = __libc_malloc
#pragma weak memalign = __libc_memalign
#pragma weak realloc = __libc_realloc
#pragma weak valloc = __libc_valloc
#pragma weak pvalloc = __libc_pvalloc
#pragma weak mallinfo = __libc_mallinfo
#pragma weak mallopt = __libc_mallopt
#else
#ifdef USE_DL_PREFIX
#define cALLOc dlcalloc
#define fREe dlfree
#define mALLOc dlmalloc
#define mEMALIGn dlmemalign
#define rEALLOc dlrealloc
#define vALLOc dlvalloc
#define pvALLOc dlpvalloc
#define mALLINFo dlmallinfo
#define mALLOPt dlmallopt
#else /* USE_DL_PREFIX */
#define cALLOc calloc
#define fREe free
#define mALLOc malloc
#define mEMALIGn memalign
#define rEALLOc realloc
#define vALLOc valloc
#define pvALLOc pvalloc
#define mALLINFo mallinfo
#define mALLOPt mallopt
#endif /* USE_DL_PREFIX */
#endif
/* Public routines */
#if __STD_C
Void_t* mALLOc(size_t);
void fREe(Void_t*);
Void_t* rEALLOc(Void_t*, size_t);
Void_t* mEMALIGn(size_t, size_t);
Void_t* vALLOc(size_t);
Void_t* pvALLOc(size_t);
Void_t* cALLOc(size_t, size_t);
void cfree(Void_t*);
int malloc_trim(size_t);
size_t malloc_usable_size(Void_t*);
void malloc_stats(void);
int mALLOPt(int, int);
struct mallinfo mALLINFo(void);
#else
Void_t* mALLOc();
void fREe();
Void_t* rEALLOc();
Void_t* mEMALIGn();
Void_t* vALLOc();
Void_t* pvALLOc();
Void_t* cALLOc();
void cfree();
int malloc_trim();
size_t malloc_usable_size();
void malloc_stats();
int mALLOPt();
struct mallinfo mALLINFo();
#endif
#ifdef __cplusplus
}; /* end of extern "C" */
#endif