blob: 0c0487228e500aaadb021352ad8eb9027949e897 [file] [log] [blame]
wdenk217c9da2002-10-25 20:35:49 +00001#if 0 /* Moved to malloc.h */
2/* ---------- To make a malloc.h, start cutting here ------------ */
3
4/*
5 A version of malloc/free/realloc written by Doug Lea and released to the
6 public domain. Send questions/comments/complaints/performance data
7 to dl@cs.oswego.edu
8
9* VERSION 2.6.6 Sun Mar 5 19:10:03 2000 Doug Lea (dl at gee)
10
11 Note: There may be an updated version of this malloc obtainable at
wdenk8bde7f72003-06-27 21:31:46 +000012 ftp://g.oswego.edu/pub/misc/malloc.c
13 Check before installing!
wdenk217c9da2002-10-25 20:35:49 +000014
15* Why use this malloc?
16
17 This is not the fastest, most space-conserving, most portable, or
18 most tunable malloc ever written. However it is among the fastest
19 while also being among the most space-conserving, portable and tunable.
20 Consistent balance across these factors results in a good general-purpose
21 allocator. For a high-level description, see
22 http://g.oswego.edu/dl/html/malloc.html
23
24* Synopsis of public routines
25
26 (Much fuller descriptions are contained in the program documentation below.)
27
28 malloc(size_t n);
29 Return a pointer to a newly allocated chunk of at least n bytes, or null
30 if no space is available.
31 free(Void_t* p);
32 Release the chunk of memory pointed to by p, or no effect if p is null.
33 realloc(Void_t* p, size_t n);
34 Return a pointer to a chunk of size n that contains the same data
35 as does chunk p up to the minimum of (n, p's size) bytes, or null
36 if no space is available. The returned pointer may or may not be
37 the same as p. If p is null, equivalent to malloc. Unless the
38 #define REALLOC_ZERO_BYTES_FREES below is set, realloc with a
39 size argument of zero (re)allocates a minimum-sized chunk.
40 memalign(size_t alignment, size_t n);
41 Return a pointer to a newly allocated chunk of n bytes, aligned
42 in accord with the alignment argument, which must be a power of
43 two.
44 valloc(size_t n);
45 Equivalent to memalign(pagesize, n), where pagesize is the page
46 size of the system (or as near to this as can be figured out from
47 all the includes/defines below.)
48 pvalloc(size_t n);
49 Equivalent to valloc(minimum-page-that-holds(n)), that is,
50 round up n to nearest pagesize.
51 calloc(size_t unit, size_t quantity);
52 Returns a pointer to quantity * unit bytes, with all locations
53 set to zero.
54 cfree(Void_t* p);
55 Equivalent to free(p).
56 malloc_trim(size_t pad);
57 Release all but pad bytes of freed top-most memory back
58 to the system. Return 1 if successful, else 0.
59 malloc_usable_size(Void_t* p);
60 Report the number usable allocated bytes associated with allocated
61 chunk p. This may or may not report more bytes than were requested,
62 due to alignment and minimum size constraints.
63 malloc_stats();
64 Prints brief summary statistics.
65 mallinfo()
66 Returns (by copy) a struct containing various summary statistics.
67 mallopt(int parameter_number, int parameter_value)
68 Changes one of the tunable parameters described below. Returns
69 1 if successful in changing the parameter, else 0.
70
71* Vital statistics:
72
73 Alignment: 8-byte
74 8 byte alignment is currently hardwired into the design. This
75 seems to suffice for all current machines and C compilers.
76
77 Assumed pointer representation: 4 or 8 bytes
78 Code for 8-byte pointers is untested by me but has worked
79 reliably by Wolfram Gloger, who contributed most of the
80 changes supporting this.
81
82 Assumed size_t representation: 4 or 8 bytes
83 Note that size_t is allowed to be 4 bytes even if pointers are 8.
84
85 Minimum overhead per allocated chunk: 4 or 8 bytes
86 Each malloced chunk has a hidden overhead of 4 bytes holding size
87 and status information.
88
89 Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead)
wdenk8bde7f72003-06-27 21:31:46 +000090 8-byte ptrs: 24/32 bytes (including, 4/8 overhead)
wdenk217c9da2002-10-25 20:35:49 +000091
92 When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
93 ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
94 needed; 4 (8) for a trailing size field
95 and 8 (16) bytes for free list pointers. Thus, the minimum
96 allocatable size is 16/24/32 bytes.
97
98 Even a request for zero bytes (i.e., malloc(0)) returns a
99 pointer to something of the minimum allocatable size.
100
101 Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes
wdenk8bde7f72003-06-27 21:31:46 +0000102 8-byte size_t: 2^63 - 16 bytes
wdenk217c9da2002-10-25 20:35:49 +0000103
104 It is assumed that (possibly signed) size_t bit values suffice to
105 represent chunk sizes. `Possibly signed' is due to the fact
106 that `size_t' may be defined on a system as either a signed or
107 an unsigned type. To be conservative, values that would appear
108 as negative numbers are avoided.
109 Requests for sizes with a negative sign bit when the request
110 size is treaded as a long will return null.
111
112 Maximum overhead wastage per allocated chunk: normally 15 bytes
113
114 Alignnment demands, plus the minimum allocatable size restriction
115 make the normal worst-case wastage 15 bytes (i.e., up to 15
116 more bytes will be allocated than were requested in malloc), with
117 two exceptions:
wdenk8bde7f72003-06-27 21:31:46 +0000118 1. Because requests for zero bytes allocate non-zero space,
119 the worst case wastage for a request of zero bytes is 24 bytes.
120 2. For requests >= mmap_threshold that are serviced via
121 mmap(), the worst case wastage is 8 bytes plus the remainder
122 from a system page (the minimal mmap unit); typically 4096 bytes.
wdenk217c9da2002-10-25 20:35:49 +0000123
124* Limitations
125
126 Here are some features that are NOT currently supported
127
128 * No user-definable hooks for callbacks and the like.
129 * No automated mechanism for fully checking that all accesses
130 to malloced memory stay within their bounds.
131 * No support for compaction.
132
133* Synopsis of compile-time options:
134
135 People have reported using previous versions of this malloc on all
136 versions of Unix, sometimes by tweaking some of the defines
137 below. It has been tested most extensively on Solaris and
138 Linux. It is also reported to work on WIN32 platforms.
139 People have also reported adapting this malloc for use in
140 stand-alone embedded systems.
141
142 The implementation is in straight, hand-tuned ANSI C. Among other
143 consequences, it uses a lot of macros. Because of this, to be at
144 all usable, this code should be compiled using an optimizing compiler
145 (for example gcc -O2) that can simplify expressions and control
146 paths.
147
148 __STD_C (default: derived from C compiler defines)
149 Nonzero if using ANSI-standard C compiler, a C++ compiler, or
150 a C compiler sufficiently close to ANSI to get away with it.
151 DEBUG (default: NOT defined)
152 Define to enable debugging. Adds fairly extensive assertion-based
153 checking to help track down memory errors, but noticeably slows down
154 execution.
155 REALLOC_ZERO_BYTES_FREES (default: NOT defined)
156 Define this if you think that realloc(p, 0) should be equivalent
157 to free(p). Otherwise, since malloc returns a unique pointer for
158 malloc(0), so does realloc(p, 0).
159 HAVE_MEMCPY (default: defined)
160 Define if you are not otherwise using ANSI STD C, but still
161 have memcpy and memset in your C library and want to use them.
162 Otherwise, simple internal versions are supplied.
163 USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)
164 Define as 1 if you want the C library versions of memset and
165 memcpy called in realloc and calloc (otherwise macro versions are used).
166 At least on some platforms, the simple macro versions usually
167 outperform libc versions.
168 HAVE_MMAP (default: defined as 1)
169 Define to non-zero to optionally make malloc() use mmap() to
170 allocate very large blocks.
171 HAVE_MREMAP (default: defined as 0 unless Linux libc set)
172 Define to non-zero to optionally make realloc() use mremap() to
173 reallocate very large blocks.
174 malloc_getpagesize (default: derived from system #includes)
175 Either a constant or routine call returning the system page size.
176 HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)
177 Optionally define if you are on a system with a /usr/include/malloc.h
178 that declares struct mallinfo. It is not at all necessary to
179 define this even if you do, but will ensure consistency.
180 INTERNAL_SIZE_T (default: size_t)
181 Define to a 32-bit type (probably `unsigned int') if you are on a
182 64-bit machine, yet do not want or need to allow malloc requests of
183 greater than 2^31 to be handled. This saves space, especially for
184 very small chunks.
185 INTERNAL_LINUX_C_LIB (default: NOT defined)
186 Defined only when compiled as part of Linux libc.
187 Also note that there is some odd internal name-mangling via defines
188 (for example, internally, `malloc' is named `mALLOc') needed
189 when compiling in this case. These look funny but don't otherwise
190 affect anything.
191 WIN32 (default: undefined)
192 Define this on MS win (95, nt) platforms to compile in sbrk emulation.
193 LACKS_UNISTD_H (default: undefined if not WIN32)
194 Define this if your system does not have a <unistd.h>.
195 LACKS_SYS_PARAM_H (default: undefined if not WIN32)
196 Define this if your system does not have a <sys/param.h>.
197 MORECORE (default: sbrk)
198 The name of the routine to call to obtain more memory from the system.
199 MORECORE_FAILURE (default: -1)
200 The value returned upon failure of MORECORE.
201 MORECORE_CLEARS (default 1)
202 True (1) if the routine mapped to MORECORE zeroes out memory (which
203 holds for sbrk).
204 DEFAULT_TRIM_THRESHOLD
205 DEFAULT_TOP_PAD
206 DEFAULT_MMAP_THRESHOLD
207 DEFAULT_MMAP_MAX
208 Default values of tunable parameters (described in detail below)
209 controlling interaction with host system routines (sbrk, mmap, etc).
210 These values may also be changed dynamically via mallopt(). The
211 preset defaults are those that give best performance for typical
212 programs/systems.
213 USE_DL_PREFIX (default: undefined)
214 Prefix all public routines with the string 'dl'. Useful to
215 quickly avoid procedure declaration conflicts and linker symbol
216 conflicts with existing memory allocation routines.
217
218
219*/
220
221
222
223
224/* Preliminaries */
225
226#ifndef __STD_C
227#ifdef __STDC__
228#define __STD_C 1
229#else
230#if __cplusplus
231#define __STD_C 1
232#else
233#define __STD_C 0
234#endif /*__cplusplus*/
235#endif /*__STDC__*/
236#endif /*__STD_C*/
237
238#ifndef Void_t
239#if (__STD_C || defined(WIN32))
240#define Void_t void
241#else
242#define Void_t char
243#endif
244#endif /*Void_t*/
245
246#if __STD_C
247#include <stddef.h> /* for size_t */
248#else
249#include <sys/types.h>
250#endif
251
252#ifdef __cplusplus
253extern "C" {
254#endif
255
256#include <stdio.h> /* needed for malloc_stats */
257
258
259/*
260 Compile-time options
261*/
262
263
264/*
265 Debugging:
266
267 Because freed chunks may be overwritten with link fields, this
268 malloc will often die when freed memory is overwritten by user
269 programs. This can be very effective (albeit in an annoying way)
270 in helping track down dangling pointers.
271
272 If you compile with -DDEBUG, a number of assertion checks are
273 enabled that will catch more memory errors. You probably won't be
274 able to make much sense of the actual assertion errors, but they
275 should help you locate incorrectly overwritten memory. The
276 checking is fairly extensive, and will slow down execution
277 noticeably. Calling malloc_stats or mallinfo with DEBUG set will
278 attempt to check every non-mmapped allocated and free chunk in the
279 course of computing the summmaries. (By nature, mmapped regions
280 cannot be checked very much automatically.)
281
282 Setting DEBUG may also be helpful if you are trying to modify
283 this code. The assertions in the check routines spell out in more
284 detail the assumptions and invariants underlying the algorithms.
285
286*/
287
288#ifdef DEBUG
289#include <assert.h>
290#else
291#define assert(x) ((void)0)
292#endif
293
294
295/*
296 INTERNAL_SIZE_T is the word-size used for internal bookkeeping
297 of chunk sizes. On a 64-bit machine, you can reduce malloc
298 overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'
299 at the expense of not being able to handle requests greater than
300 2^31. This limitation is hardly ever a concern; you are encouraged
301 to set this. However, the default version is the same as size_t.
302*/
303
304#ifndef INTERNAL_SIZE_T
305#define INTERNAL_SIZE_T size_t
306#endif
307
308/*
309 REALLOC_ZERO_BYTES_FREES should be set if a call to
310 realloc with zero bytes should be the same as a call to free.
311 Some people think it should. Otherwise, since this malloc
312 returns a unique pointer for malloc(0), so does realloc(p, 0).
313*/
314
315
316/* #define REALLOC_ZERO_BYTES_FREES */
317
318
319/*
320 WIN32 causes an emulation of sbrk to be compiled in
321 mmap-based options are not currently supported in WIN32.
322*/
323
324/* #define WIN32 */
325#ifdef WIN32
326#define MORECORE wsbrk
327#define HAVE_MMAP 0
328
329#define LACKS_UNISTD_H
330#define LACKS_SYS_PARAM_H
331
332/*
333 Include 'windows.h' to get the necessary declarations for the
334 Microsoft Visual C++ data structures and routines used in the 'sbrk'
335 emulation.
336
337 Define WIN32_LEAN_AND_MEAN so that only the essential Microsoft
338 Visual C++ header files are included.
339*/
340#define WIN32_LEAN_AND_MEAN
341#include <windows.h>
342#endif
343
344
345/*
346 HAVE_MEMCPY should be defined if you are not otherwise using
347 ANSI STD C, but still have memcpy and memset in your C library
348 and want to use them in calloc and realloc. Otherwise simple
349 macro versions are defined here.
350
351 USE_MEMCPY should be defined as 1 if you actually want to
352 have memset and memcpy called. People report that the macro
353 versions are often enough faster than libc versions on many
354 systems that it is better to use them.
355
356*/
357
358#define HAVE_MEMCPY
359
360#ifndef USE_MEMCPY
361#ifdef HAVE_MEMCPY
362#define USE_MEMCPY 1
363#else
364#define USE_MEMCPY 0
365#endif
366#endif
367
368#if (__STD_C || defined(HAVE_MEMCPY))
369
370#if __STD_C
371void* memset(void*, int, size_t);
372void* memcpy(void*, const void*, size_t);
373#else
374#ifdef WIN32
wdenk8bde7f72003-06-27 21:31:46 +0000375/* On Win32 platforms, 'memset()' and 'memcpy()' are already declared in */
376/* 'windows.h' */
wdenk217c9da2002-10-25 20:35:49 +0000377#else
378Void_t* memset();
379Void_t* memcpy();
380#endif
381#endif
382#endif
383
384#if USE_MEMCPY
385
386/* The following macros are only invoked with (2n+1)-multiples of
387 INTERNAL_SIZE_T units, with a positive integer n. This is exploited
388 for fast inline execution when n is small. */
389
390#define MALLOC_ZERO(charp, nbytes) \
391do { \
392 INTERNAL_SIZE_T mzsz = (nbytes); \
393 if(mzsz <= 9*sizeof(mzsz)) { \
394 INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \
395 if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \
wdenk8bde7f72003-06-27 21:31:46 +0000396 *mz++ = 0; \
wdenk217c9da2002-10-25 20:35:49 +0000397 if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \
wdenk8bde7f72003-06-27 21:31:46 +0000398 *mz++ = 0; \
399 if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \
400 *mz++ = 0; }}} \
401 *mz++ = 0; \
402 *mz++ = 0; \
403 *mz = 0; \
wdenk217c9da2002-10-25 20:35:49 +0000404 } else memset((charp), 0, mzsz); \
405} while(0)
406
407#define MALLOC_COPY(dest,src,nbytes) \
408do { \
409 INTERNAL_SIZE_T mcsz = (nbytes); \
410 if(mcsz <= 9*sizeof(mcsz)) { \
411 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \
412 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \
413 if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
wdenk8bde7f72003-06-27 21:31:46 +0000414 *mcdst++ = *mcsrc++; \
wdenk217c9da2002-10-25 20:35:49 +0000415 if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
wdenk8bde7f72003-06-27 21:31:46 +0000416 *mcdst++ = *mcsrc++; \
417 if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \
418 *mcdst++ = *mcsrc++; }}} \
419 *mcdst++ = *mcsrc++; \
420 *mcdst++ = *mcsrc++; \
421 *mcdst = *mcsrc ; \
wdenk217c9da2002-10-25 20:35:49 +0000422 } else memcpy(dest, src, mcsz); \
423} while(0)
424
425#else /* !USE_MEMCPY */
426
427/* Use Duff's device for good zeroing/copying performance. */
428
429#define MALLOC_ZERO(charp, nbytes) \
430do { \
431 INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \
432 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
433 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
434 switch (mctmp) { \
435 case 0: for(;;) { *mzp++ = 0; \
436 case 7: *mzp++ = 0; \
437 case 6: *mzp++ = 0; \
438 case 5: *mzp++ = 0; \
439 case 4: *mzp++ = 0; \
440 case 3: *mzp++ = 0; \
441 case 2: *mzp++ = 0; \
442 case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \
443 } \
444} while(0)
445
446#define MALLOC_COPY(dest,src,nbytes) \
447do { \
448 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \
449 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \
450 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \
451 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \
452 switch (mctmp) { \
453 case 0: for(;;) { *mcdst++ = *mcsrc++; \
454 case 7: *mcdst++ = *mcsrc++; \
455 case 6: *mcdst++ = *mcsrc++; \
456 case 5: *mcdst++ = *mcsrc++; \
457 case 4: *mcdst++ = *mcsrc++; \
458 case 3: *mcdst++ = *mcsrc++; \
459 case 2: *mcdst++ = *mcsrc++; \
460 case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \
461 } \
462} while(0)
463
464#endif
465
466
467/*
468 Define HAVE_MMAP to optionally make malloc() use mmap() to
469 allocate very large blocks. These will be returned to the
470 operating system immediately after a free().
471*/
472
473#ifndef HAVE_MMAP
474#define HAVE_MMAP 1
475#endif
476
477/*
478 Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
479 large blocks. This is currently only possible on Linux with
480 kernel versions newer than 1.3.77.
481*/
482
483#ifndef HAVE_MREMAP
484#ifdef INTERNAL_LINUX_C_LIB
485#define HAVE_MREMAP 1
486#else
487#define HAVE_MREMAP 0
488#endif
489#endif
490
491#if HAVE_MMAP
492
493#include <unistd.h>
494#include <fcntl.h>
495#include <sys/mman.h>
496
497#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
498#define MAP_ANONYMOUS MAP_ANON
499#endif
500
501#endif /* HAVE_MMAP */
502
503/*
504 Access to system page size. To the extent possible, this malloc
505 manages memory from the system in page-size units.
506
507 The following mechanics for getpagesize were adapted from
508 bsd/gnu getpagesize.h
509*/
510
511#ifndef LACKS_UNISTD_H
512# include <unistd.h>
513#endif
514
515#ifndef malloc_getpagesize
516# ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */
517# ifndef _SC_PAGE_SIZE
518# define _SC_PAGE_SIZE _SC_PAGESIZE
519# endif
520# endif
521# ifdef _SC_PAGE_SIZE
522# define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
523# else
524# if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
525 extern size_t getpagesize();
526# define malloc_getpagesize getpagesize()
527# else
528# ifdef WIN32
529# define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */
530# else
531# ifndef LACKS_SYS_PARAM_H
532# include <sys/param.h>
533# endif
534# ifdef EXEC_PAGESIZE
535# define malloc_getpagesize EXEC_PAGESIZE
536# else
537# ifdef NBPG
538# ifndef CLSIZE
539# define malloc_getpagesize NBPG
540# else
541# define malloc_getpagesize (NBPG * CLSIZE)
542# endif
543# else
544# ifdef NBPC
545# define malloc_getpagesize NBPC
546# else
547# ifdef PAGESIZE
548# define malloc_getpagesize PAGESIZE
549# else
550# define malloc_getpagesize (4096) /* just guess */
551# endif
552# endif
553# endif
554# endif
555# endif
556# endif
557# endif
558#endif
559
560
wdenk217c9da2002-10-25 20:35:49 +0000561/*
562
563 This version of malloc supports the standard SVID/XPG mallinfo
564 routine that returns a struct containing the same kind of
565 information you can get from malloc_stats. It should work on
566 any SVID/XPG compliant system that has a /usr/include/malloc.h
567 defining struct mallinfo. (If you'd like to install such a thing
568 yourself, cut out the preliminary declarations as described above
569 and below and save them in a malloc.h file. But there's no
570 compelling reason to bother to do this.)
571
572 The main declaration needed is the mallinfo struct that is returned
573 (by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a
574 bunch of fields, most of which are not even meaningful in this
575 version of malloc. Some of these fields are are instead filled by
576 mallinfo() with other numbers that might possibly be of interest.
577
578 HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
579 /usr/include/malloc.h file that includes a declaration of struct
580 mallinfo. If so, it is included; else an SVID2/XPG2 compliant
581 version is declared below. These must be precisely the same for
582 mallinfo() to work.
583
584*/
585
586/* #define HAVE_USR_INCLUDE_MALLOC_H */
587
588#if HAVE_USR_INCLUDE_MALLOC_H
589#include "/usr/include/malloc.h"
590#else
591
592/* SVID2/XPG mallinfo structure */
593
594struct mallinfo {
595 int arena; /* total space allocated from system */
596 int ordblks; /* number of non-inuse chunks */
597 int smblks; /* unused -- always zero */
598 int hblks; /* number of mmapped regions */
599 int hblkhd; /* total space in mmapped regions */
600 int usmblks; /* unused -- always zero */
601 int fsmblks; /* unused -- always zero */
602 int uordblks; /* total allocated space */
603 int fordblks; /* total non-inuse space */
604 int keepcost; /* top-most, releasable (via malloc_trim) space */
605};
606
607/* SVID2/XPG mallopt options */
608
609#define M_MXFAST 1 /* UNUSED in this malloc */
610#define M_NLBLKS 2 /* UNUSED in this malloc */
611#define M_GRAIN 3 /* UNUSED in this malloc */
612#define M_KEEP 4 /* UNUSED in this malloc */
613
614#endif
615
616/* mallopt options that actually do something */
617
618#define M_TRIM_THRESHOLD -1
619#define M_TOP_PAD -2
620#define M_MMAP_THRESHOLD -3
621#define M_MMAP_MAX -4
622
623
wdenk217c9da2002-10-25 20:35:49 +0000624#ifndef DEFAULT_TRIM_THRESHOLD
625#define DEFAULT_TRIM_THRESHOLD (128 * 1024)
626#endif
627
628/*
629 M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
630 to keep before releasing via malloc_trim in free().
631
632 Automatic trimming is mainly useful in long-lived programs.
633 Because trimming via sbrk can be slow on some systems, and can
634 sometimes be wasteful (in cases where programs immediately
635 afterward allocate more large chunks) the value should be high
636 enough so that your overall system performance would improve by
637 releasing.
638
639 The trim threshold and the mmap control parameters (see below)
640 can be traded off with one another. Trimming and mmapping are
641 two different ways of releasing unused memory back to the
642 system. Between these two, it is often possible to keep
643 system-level demands of a long-lived program down to a bare
644 minimum. For example, in one test suite of sessions measuring
645 the XF86 X server on Linux, using a trim threshold of 128K and a
646 mmap threshold of 192K led to near-minimal long term resource
647 consumption.
648
649 If you are using this malloc in a long-lived program, it should
650 pay to experiment with these values. As a rough guide, you
651 might set to a value close to the average size of a process
652 (program) running on your system. Releasing this much memory
653 would allow such a process to run in memory. Generally, it's
654 worth it to tune for trimming rather tham memory mapping when a
655 program undergoes phases where several large chunks are
656 allocated and released in ways that can reuse each other's
657 storage, perhaps mixed with phases where there are no such
658 chunks at all. And in well-behaved long-lived programs,
659 controlling release of large blocks via trimming versus mapping
660 is usually faster.
661
662 However, in most programs, these parameters serve mainly as
663 protection against the system-level effects of carrying around
664 massive amounts of unneeded memory. Since frequent calls to
665 sbrk, mmap, and munmap otherwise degrade performance, the default
666 parameters are set to relatively high values that serve only as
667 safeguards.
668
669 The default trim value is high enough to cause trimming only in
670 fairly extreme (by current memory consumption standards) cases.
671 It must be greater than page size to have any useful effect. To
672 disable trimming completely, you can set to (unsigned long)(-1);
673
674
675*/
676
677
678#ifndef DEFAULT_TOP_PAD
679#define DEFAULT_TOP_PAD (0)
680#endif
681
682/*
683 M_TOP_PAD is the amount of extra `padding' space to allocate or
684 retain whenever sbrk is called. It is used in two ways internally:
685
686 * When sbrk is called to extend the top of the arena to satisfy
wdenk8bde7f72003-06-27 21:31:46 +0000687 a new malloc request, this much padding is added to the sbrk
688 request.
wdenk217c9da2002-10-25 20:35:49 +0000689
690 * When malloc_trim is called automatically from free(),
wdenk8bde7f72003-06-27 21:31:46 +0000691 it is used as the `pad' argument.
wdenk217c9da2002-10-25 20:35:49 +0000692
693 In both cases, the actual amount of padding is rounded
694 so that the end of the arena is always a system page boundary.
695
696 The main reason for using padding is to avoid calling sbrk so
697 often. Having even a small pad greatly reduces the likelihood
698 that nearly every malloc request during program start-up (or
699 after trimming) will invoke sbrk, which needlessly wastes
700 time.
701
702 Automatic rounding-up to page-size units is normally sufficient
703 to avoid measurable overhead, so the default is 0. However, in
704 systems where sbrk is relatively slow, it can pay to increase
705 this value, at the expense of carrying around more memory than
706 the program needs.
707
708*/
709
710
711#ifndef DEFAULT_MMAP_THRESHOLD
712#define DEFAULT_MMAP_THRESHOLD (128 * 1024)
713#endif
714
715/*
716
717 M_MMAP_THRESHOLD is the request size threshold for using mmap()
718 to service a request. Requests of at least this size that cannot
719 be allocated using already-existing space will be serviced via mmap.
720 (If enough normal freed space already exists it is used instead.)
721
722 Using mmap segregates relatively large chunks of memory so that
723 they can be individually obtained and released from the host
724 system. A request serviced through mmap is never reused by any
725 other request (at least not directly; the system may just so
726 happen to remap successive requests to the same locations).
727
728 Segregating space in this way has the benefit that mmapped space
729 can ALWAYS be individually released back to the system, which
730 helps keep the system level memory demands of a long-lived
731 program low. Mapped memory can never become `locked' between
732 other chunks, as can happen with normally allocated chunks, which
733 menas that even trimming via malloc_trim would not release them.
734
735 However, it has the disadvantages that:
736
wdenk8bde7f72003-06-27 21:31:46 +0000737 1. The space cannot be reclaimed, consolidated, and then
738 used to service later requests, as happens with normal chunks.
739 2. It can lead to more wastage because of mmap page alignment
740 requirements
741 3. It causes malloc performance to be more dependent on host
742 system memory management support routines which may vary in
743 implementation quality and may impose arbitrary
744 limitations. Generally, servicing a request via normal
745 malloc steps is faster than going through a system's mmap.
wdenk217c9da2002-10-25 20:35:49 +0000746
747 All together, these considerations should lead you to use mmap
748 only for relatively large requests.
749
750
751*/
752
753
wdenk217c9da2002-10-25 20:35:49 +0000754#ifndef DEFAULT_MMAP_MAX
755#if HAVE_MMAP
756#define DEFAULT_MMAP_MAX (64)
757#else
758#define DEFAULT_MMAP_MAX (0)
759#endif
760#endif
761
762/*
763 M_MMAP_MAX is the maximum number of requests to simultaneously
764 service using mmap. This parameter exists because:
765
wdenk8bde7f72003-06-27 21:31:46 +0000766 1. Some systems have a limited number of internal tables for
767 use by mmap.
768 2. In most systems, overreliance on mmap can degrade overall
769 performance.
770 3. If a program allocates many large regions, it is probably
771 better off using normal sbrk-based allocation routines that
772 can reclaim and reallocate normal heap memory. Using a
773 small value allows transition into this mode after the
774 first few allocations.
wdenk217c9da2002-10-25 20:35:49 +0000775
776 Setting to 0 disables all use of mmap. If HAVE_MMAP is not set,
777 the default value is 0, and attempts to set it to non-zero values
778 in mallopt will fail.
779*/
780
781
wdenk217c9da2002-10-25 20:35:49 +0000782/*
783 USE_DL_PREFIX will prefix all public routines with the string 'dl'.
784 Useful to quickly avoid procedure declaration conflicts and linker
785 symbol conflicts with existing memory allocation routines.
786
787*/
788
789/* #define USE_DL_PREFIX */
790
791
wdenk217c9da2002-10-25 20:35:49 +0000792/*
793
794 Special defines for linux libc
795
796 Except when compiled using these special defines for Linux libc
797 using weak aliases, this malloc is NOT designed to work in
798 multithreaded applications. No semaphores or other concurrency
799 control are provided to ensure that multiple malloc or free calls
800 don't run at the same time, which could be disasterous. A single
801 semaphore could be used across malloc, realloc, and free (which is
802 essentially the effect of the linux weak alias approach). It would
803 be hard to obtain finer granularity.
804
805*/
806
807
808#ifdef INTERNAL_LINUX_C_LIB
809
810#if __STD_C
811
812Void_t * __default_morecore_init (ptrdiff_t);
813Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init;
814
815#else
816
817Void_t * __default_morecore_init ();
818Void_t *(*__morecore)() = __default_morecore_init;
819
820#endif
821
822#define MORECORE (*__morecore)
823#define MORECORE_FAILURE 0
824#define MORECORE_CLEARS 1
825
826#else /* INTERNAL_LINUX_C_LIB */
827
828#if __STD_C
829extern Void_t* sbrk(ptrdiff_t);
830#else
831extern Void_t* sbrk();
832#endif
833
834#ifndef MORECORE
835#define MORECORE sbrk
836#endif
837
838#ifndef MORECORE_FAILURE
839#define MORECORE_FAILURE -1
840#endif
841
842#ifndef MORECORE_CLEARS
843#define MORECORE_CLEARS 1
844#endif
845
846#endif /* INTERNAL_LINUX_C_LIB */
847
848#if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__)
849
850#define cALLOc __libc_calloc
851#define fREe __libc_free
852#define mALLOc __libc_malloc
853#define mEMALIGn __libc_memalign
854#define rEALLOc __libc_realloc
855#define vALLOc __libc_valloc
856#define pvALLOc __libc_pvalloc
857#define mALLINFo __libc_mallinfo
858#define mALLOPt __libc_mallopt
859
860#pragma weak calloc = __libc_calloc
861#pragma weak free = __libc_free
862#pragma weak cfree = __libc_free
863#pragma weak malloc = __libc_malloc
864#pragma weak memalign = __libc_memalign
865#pragma weak realloc = __libc_realloc
866#pragma weak valloc = __libc_valloc
867#pragma weak pvalloc = __libc_pvalloc
868#pragma weak mallinfo = __libc_mallinfo
869#pragma weak mallopt = __libc_mallopt
870
871#else
872
873#ifdef USE_DL_PREFIX
874#define cALLOc dlcalloc
875#define fREe dlfree
876#define mALLOc dlmalloc
877#define mEMALIGn dlmemalign
878#define rEALLOc dlrealloc
879#define vALLOc dlvalloc
880#define pvALLOc dlpvalloc
881#define mALLINFo dlmallinfo
882#define mALLOPt dlmallopt
883#else /* USE_DL_PREFIX */
884#define cALLOc calloc
885#define fREe free
886#define mALLOc malloc
887#define mEMALIGn memalign
888#define rEALLOc realloc
889#define vALLOc valloc
890#define pvALLOc pvalloc
891#define mALLINFo mallinfo
892#define mALLOPt mallopt
893#endif /* USE_DL_PREFIX */
894
895#endif
896
897/* Public routines */
898
899#if __STD_C
900
901Void_t* mALLOc(size_t);
902void fREe(Void_t*);
903Void_t* rEALLOc(Void_t*, size_t);
904Void_t* mEMALIGn(size_t, size_t);
905Void_t* vALLOc(size_t);
906Void_t* pvALLOc(size_t);
907Void_t* cALLOc(size_t, size_t);
908void cfree(Void_t*);
909int malloc_trim(size_t);
910size_t malloc_usable_size(Void_t*);
911void malloc_stats();
912int mALLOPt(int, int);
913struct mallinfo mALLINFo(void);
914#else
915Void_t* mALLOc();
916void fREe();
917Void_t* rEALLOc();
918Void_t* mEMALIGn();
919Void_t* vALLOc();
920Void_t* pvALLOc();
921Void_t* cALLOc();
922void cfree();
923int malloc_trim();
924size_t malloc_usable_size();
925void malloc_stats();
926int mALLOPt();
927struct mallinfo mALLINFo();
928#endif
929
930
931#ifdef __cplusplus
932}; /* end of extern "C" */
933#endif
934
935/* ---------- To make a malloc.h, end cutting here ------------ */
936#else /* Moved to malloc.h */
937
938#include <malloc.h>
939#if 0
940#if __STD_C
941static void malloc_update_mallinfo (void);
942void malloc_stats (void);
943#else
944static void malloc_update_mallinfo ();
945void malloc_stats();
946#endif
947#endif /* 0 */
948
949#endif /* 0 */ /* Moved to malloc.h */
950#include <common.h>
951
952/*
953 Emulation of sbrk for WIN32
954 All code within the ifdef WIN32 is untested by me.
955
956 Thanks to Martin Fong and others for supplying this.
957*/
958
959
960#ifdef WIN32
961
962#define AlignPage(add) (((add) + (malloc_getpagesize-1)) & \
963~(malloc_getpagesize-1))
964#define AlignPage64K(add) (((add) + (0x10000 - 1)) & ~(0x10000 - 1))
965
966/* resrve 64MB to insure large contiguous space */
967#define RESERVED_SIZE (1024*1024*64)
968#define NEXT_SIZE (2048*1024)
969#define TOP_MEMORY ((unsigned long)2*1024*1024*1024)
970
971struct GmListElement;
972typedef struct GmListElement GmListElement;
973
974struct GmListElement
975{
976 GmListElement* next;
977 void* base;
978};
979
980static GmListElement* head = 0;
981static unsigned int gNextAddress = 0;
982static unsigned int gAddressBase = 0;
983static unsigned int gAllocatedSize = 0;
984
985static
986GmListElement* makeGmListElement (void* bas)
987{
988 GmListElement* this;
989 this = (GmListElement*)(void*)LocalAlloc (0, sizeof (GmListElement));
990 assert (this);
991 if (this)
992 {
993 this->base = bas;
994 this->next = head;
995 head = this;
996 }
997 return this;
998}
999
1000void gcleanup ()
1001{
1002 BOOL rval;
1003 assert ( (head == NULL) || (head->base == (void*)gAddressBase));
1004 if (gAddressBase && (gNextAddress - gAddressBase))
1005 {
1006 rval = VirtualFree ((void*)gAddressBase,
1007 gNextAddress - gAddressBase,
1008 MEM_DECOMMIT);
wdenk8bde7f72003-06-27 21:31:46 +00001009 assert (rval);
wdenk217c9da2002-10-25 20:35:49 +00001010 }
1011 while (head)
1012 {
1013 GmListElement* next = head->next;
1014 rval = VirtualFree (head->base, 0, MEM_RELEASE);
1015 assert (rval);
1016 LocalFree (head);
1017 head = next;
1018 }
1019}
1020
1021static
1022void* findRegion (void* start_address, unsigned long size)
1023{
1024 MEMORY_BASIC_INFORMATION info;
1025 if (size >= TOP_MEMORY) return NULL;
1026
1027 while ((unsigned long)start_address + size < TOP_MEMORY)
1028 {
1029 VirtualQuery (start_address, &info, sizeof (info));
1030 if ((info.State == MEM_FREE) && (info.RegionSize >= size))
1031 return start_address;
1032 else
1033 {
wdenk8bde7f72003-06-27 21:31:46 +00001034 /* Requested region is not available so see if the */
1035 /* next region is available. Set 'start_address' */
1036 /* to the next region and call 'VirtualQuery()' */
1037 /* again. */
wdenk217c9da2002-10-25 20:35:49 +00001038
1039 start_address = (char*)info.BaseAddress + info.RegionSize;
1040
wdenk8bde7f72003-06-27 21:31:46 +00001041 /* Make sure we start looking for the next region */
1042 /* on the *next* 64K boundary. Otherwise, even if */
1043 /* the new region is free according to */
1044 /* 'VirtualQuery()', the subsequent call to */
1045 /* 'VirtualAlloc()' (which follows the call to */
1046 /* this routine in 'wsbrk()') will round *down* */
1047 /* the requested address to a 64K boundary which */
1048 /* we already know is an address in the */
1049 /* unavailable region. Thus, the subsequent call */
1050 /* to 'VirtualAlloc()' will fail and bring us back */
1051 /* here, causing us to go into an infinite loop. */
wdenk217c9da2002-10-25 20:35:49 +00001052
1053 start_address =
1054 (void *) AlignPage64K((unsigned long) start_address);
1055 }
1056 }
1057 return NULL;
1058
1059}
1060
1061
1062void* wsbrk (long size)
1063{
1064 void* tmp;
1065 if (size > 0)
1066 {
1067 if (gAddressBase == 0)
1068 {
1069 gAllocatedSize = max (RESERVED_SIZE, AlignPage (size));
1070 gNextAddress = gAddressBase =
1071 (unsigned int)VirtualAlloc (NULL, gAllocatedSize,
1072 MEM_RESERVE, PAGE_NOACCESS);
1073 } else if (AlignPage (gNextAddress + size) > (gAddressBase +
1074gAllocatedSize))
1075 {
1076 long new_size = max (NEXT_SIZE, AlignPage (size));
1077 void* new_address = (void*)(gAddressBase+gAllocatedSize);
1078 do
1079 {
1080 new_address = findRegion (new_address, new_size);
1081
1082 if (new_address == 0)
1083 return (void*)-1;
1084
1085 gAddressBase = gNextAddress =
1086 (unsigned int)VirtualAlloc (new_address, new_size,
1087 MEM_RESERVE, PAGE_NOACCESS);
wdenk8bde7f72003-06-27 21:31:46 +00001088 /* repeat in case of race condition */
1089 /* The region that we found has been snagged */
1090 /* by another thread */
wdenk217c9da2002-10-25 20:35:49 +00001091 }
1092 while (gAddressBase == 0);
1093
1094 assert (new_address == (void*)gAddressBase);
1095
1096 gAllocatedSize = new_size;
1097
1098 if (!makeGmListElement ((void*)gAddressBase))
1099 return (void*)-1;
1100 }
1101 if ((size + gNextAddress) > AlignPage (gNextAddress))
1102 {
1103 void* res;
1104 res = VirtualAlloc ((void*)AlignPage (gNextAddress),
1105 (size + gNextAddress -
1106 AlignPage (gNextAddress)),
1107 MEM_COMMIT, PAGE_READWRITE);
1108 if (res == 0)
1109 return (void*)-1;
1110 }
1111 tmp = (void*)gNextAddress;
1112 gNextAddress = (unsigned int)tmp + size;
1113 return tmp;
1114 }
1115 else if (size < 0)
1116 {
1117 unsigned int alignedGoal = AlignPage (gNextAddress + size);
1118 /* Trim by releasing the virtual memory */
1119 if (alignedGoal >= gAddressBase)
1120 {
1121 VirtualFree ((void*)alignedGoal, gNextAddress - alignedGoal,
1122 MEM_DECOMMIT);
1123 gNextAddress = gNextAddress + size;
1124 return (void*)gNextAddress;
1125 }
1126 else
1127 {
1128 VirtualFree ((void*)gAddressBase, gNextAddress - gAddressBase,
1129 MEM_DECOMMIT);
1130 gNextAddress = gAddressBase;
1131 return (void*)-1;
1132 }
1133 }
1134 else
1135 {
1136 return (void*)gNextAddress;
1137 }
1138}
1139
1140#endif
1141
1142
1143
1144/*
1145 Type declarations
1146*/
1147
1148
1149struct malloc_chunk
1150{
1151 INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */
1152 INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */
1153 struct malloc_chunk* fd; /* double links -- used only if free. */
1154 struct malloc_chunk* bk;
1155};
1156
1157typedef struct malloc_chunk* mchunkptr;
1158
1159/*
1160
1161 malloc_chunk details:
1162
1163 (The following includes lightly edited explanations by Colin Plumb.)
1164
1165 Chunks of memory are maintained using a `boundary tag' method as
1166 described in e.g., Knuth or Standish. (See the paper by Paul
1167 Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
1168 survey of such techniques.) Sizes of free chunks are stored both
1169 in the front of each chunk and at the end. This makes
1170 consolidating fragmented chunks into bigger chunks very fast. The
1171 size fields also hold bits representing whether chunks are free or
1172 in use.
1173
1174 An allocated chunk looks like this:
1175
1176
1177 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
wdenk8bde7f72003-06-27 21:31:46 +00001178 | Size of previous chunk, if allocated | |
1179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1180 | Size of chunk, in bytes |P|
wdenk217c9da2002-10-25 20:35:49 +00001181 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
wdenk8bde7f72003-06-27 21:31:46 +00001182 | User data starts here... .
1183 . .
1184 . (malloc_usable_space() bytes) .
1185 . |
wdenk217c9da2002-10-25 20:35:49 +00001186nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
wdenk8bde7f72003-06-27 21:31:46 +00001187 | Size of chunk |
1188 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
wdenk217c9da2002-10-25 20:35:49 +00001189
1190
1191 Where "chunk" is the front of the chunk for the purpose of most of
1192 the malloc code, but "mem" is the pointer that is returned to the
1193 user. "Nextchunk" is the beginning of the next contiguous chunk.
1194
1195 Chunks always begin on even word boundries, so the mem portion
1196 (which is returned to the user) is also on an even word boundary, and
1197 thus double-word aligned.
1198
1199 Free chunks are stored in circular doubly-linked lists, and look like this:
1200
1201 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
wdenk8bde7f72003-06-27 21:31:46 +00001202 | Size of previous chunk |
1203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
wdenk217c9da2002-10-25 20:35:49 +00001204 `head:' | Size of chunk, in bytes |P|
1205 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
wdenk8bde7f72003-06-27 21:31:46 +00001206 | Forward pointer to next chunk in list |
1207 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1208 | Back pointer to previous chunk in list |
1209 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1210 | Unused space (may be 0 bytes long) .
1211 . .
1212 . |
wdenk217c9da2002-10-25 20:35:49 +00001213nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1214 `foot:' | Size of chunk, in bytes |
wdenk8bde7f72003-06-27 21:31:46 +00001215 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
wdenk217c9da2002-10-25 20:35:49 +00001216
1217 The P (PREV_INUSE) bit, stored in the unused low-order bit of the
1218 chunk size (which is always a multiple of two words), is an in-use
1219 bit for the *previous* chunk. If that bit is *clear*, then the
1220 word before the current chunk size contains the previous chunk
1221 size, and can be used to find the front of the previous chunk.
1222 (The very first chunk allocated always has this bit set,
1223 preventing access to non-existent (or non-owned) memory.)
1224
1225 Note that the `foot' of the current chunk is actually represented
1226 as the prev_size of the NEXT chunk. (This makes it easier to
1227 deal with alignments etc).
1228
1229 The two exceptions to all this are
1230
1231 1. The special chunk `top', which doesn't bother using the
wdenk8bde7f72003-06-27 21:31:46 +00001232 trailing size field since there is no
1233 next contiguous chunk that would have to index off it. (After
1234 initialization, `top' is forced to always exist. If it would
1235 become less than MINSIZE bytes long, it is replenished via
1236 malloc_extend_top.)
wdenk217c9da2002-10-25 20:35:49 +00001237
1238 2. Chunks allocated via mmap, which have the second-lowest-order
wdenk8bde7f72003-06-27 21:31:46 +00001239 bit (IS_MMAPPED) set in their size fields. Because they are
1240 never merged or traversed from any other chunk, they have no
1241 foot size or inuse information.
wdenk217c9da2002-10-25 20:35:49 +00001242
1243 Available chunks are kept in any of several places (all declared below):
1244
1245 * `av': An array of chunks serving as bin headers for consolidated
1246 chunks. Each bin is doubly linked. The bins are approximately
1247 proportionally (log) spaced. There are a lot of these bins
1248 (128). This may look excessive, but works very well in
1249 practice. All procedures maintain the invariant that no
1250 consolidated chunk physically borders another one. Chunks in
1251 bins are kept in size order, with ties going to the
1252 approximately least recently used chunk.
1253
1254 The chunks in each bin are maintained in decreasing sorted order by
1255 size. This is irrelevant for the small bins, which all contain
1256 the same-sized chunks, but facilitates best-fit allocation for
1257 larger chunks. (These lists are just sequential. Keeping them in
1258 order almost never requires enough traversal to warrant using
1259 fancier ordered data structures.) Chunks of the same size are
1260 linked with the most recently freed at the front, and allocations
1261 are taken from the back. This results in LRU or FIFO allocation
1262 order, which tends to give each chunk an equal opportunity to be
1263 consolidated with adjacent freed chunks, resulting in larger free
1264 chunks and less fragmentation.
1265
1266 * `top': The top-most available chunk (i.e., the one bordering the
1267 end of available memory) is treated specially. It is never
1268 included in any bin, is used only if no other chunk is
1269 available, and is released back to the system if it is very
1270 large (see M_TRIM_THRESHOLD).
1271
1272 * `last_remainder': A bin holding only the remainder of the
1273 most recently split (non-top) chunk. This bin is checked
1274 before other non-fitting chunks, so as to provide better
1275 locality for runs of sequentially allocated chunks.
1276
1277 * Implicitly, through the host system's memory mapping tables.
1278 If supported, requests greater than a threshold are usually
1279 serviced via calls to mmap, and then later released via munmap.
1280
1281*/
wdenk217c9da2002-10-25 20:35:49 +00001282
wdenk217c9da2002-10-25 20:35:49 +00001283/* sizes, alignments */
1284
1285#define SIZE_SZ (sizeof(INTERNAL_SIZE_T))
1286#define MALLOC_ALIGNMENT (SIZE_SZ + SIZE_SZ)
1287#define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1)
1288#define MINSIZE (sizeof(struct malloc_chunk))
1289
1290/* conversion from malloc headers to user pointers, and back */
1291
1292#define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ))
1293#define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))
1294
1295/* pad request bytes into a usable size */
1296
1297#define request2size(req) \
1298 (((long)((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \
1299 (long)(MINSIZE + MALLOC_ALIGN_MASK)) ? MINSIZE : \
1300 (((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) & ~(MALLOC_ALIGN_MASK)))
1301
1302/* Check if m has acceptable alignment */
1303
1304#define aligned_OK(m) (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0)
1305
1306
1307
1308
1309/*
1310 Physical chunk operations
1311*/
1312
1313
1314/* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
1315
1316#define PREV_INUSE 0x1
1317
1318/* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
1319
1320#define IS_MMAPPED 0x2
1321
1322/* Bits to mask off when extracting size */
1323
1324#define SIZE_BITS (PREV_INUSE|IS_MMAPPED)
1325
1326
1327/* Ptr to next physical malloc_chunk. */
1328
1329#define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) ))
1330
1331/* Ptr to previous physical malloc_chunk */
1332
1333#define prev_chunk(p)\
1334 ((mchunkptr)( ((char*)(p)) - ((p)->prev_size) ))
1335
1336
1337/* Treat space at ptr + offset as a chunk */
1338
1339#define chunk_at_offset(p, s) ((mchunkptr)(((char*)(p)) + (s)))
1340
1341
1342
1343
1344/*
1345 Dealing with use bits
1346*/
1347
1348/* extract p's inuse bit */
1349
1350#define inuse(p)\
1351((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE)
1352
1353/* extract inuse bit of previous chunk */
1354
1355#define prev_inuse(p) ((p)->size & PREV_INUSE)
1356
1357/* check for mmap()'ed chunk */
1358
1359#define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED)
1360
1361/* set/clear chunk as in use without otherwise disturbing */
1362
1363#define set_inuse(p)\
1364((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE
1365
1366#define clear_inuse(p)\
1367((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE)
1368
1369/* check/set/clear inuse bits in known places */
1370
1371#define inuse_bit_at_offset(p, s)\
1372 (((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE)
1373
1374#define set_inuse_bit_at_offset(p, s)\
1375 (((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE)
1376
1377#define clear_inuse_bit_at_offset(p, s)\
1378 (((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE))
1379
1380
1381
1382
1383/*
1384 Dealing with size fields
1385*/
1386
1387/* Get size, ignoring use bits */
1388
1389#define chunksize(p) ((p)->size & ~(SIZE_BITS))
1390
1391/* Set size at head, without disturbing its use bit */
1392
1393#define set_head_size(p, s) ((p)->size = (((p)->size & PREV_INUSE) | (s)))
1394
1395/* Set size/use ignoring previous bits in header */
1396
1397#define set_head(p, s) ((p)->size = (s))
1398
1399/* Set size at footer (only when chunk is not in use) */
1400
1401#define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_size = (s))
1402
1403
1404
1405
1406
1407/*
1408 Bins
1409
1410 The bins, `av_' are an array of pairs of pointers serving as the
1411 heads of (initially empty) doubly-linked lists of chunks, laid out
1412 in a way so that each pair can be treated as if it were in a
1413 malloc_chunk. (This way, the fd/bk offsets for linking bin heads
1414 and chunks are the same).
1415
1416 Bins for sizes < 512 bytes contain chunks of all the same size, spaced
1417 8 bytes apart. Larger bins are approximately logarithmically
1418 spaced. (See the table below.) The `av_' array is never mentioned
1419 directly in the code, but instead via bin access macros.
1420
1421 Bin layout:
1422
1423 64 bins of size 8
1424 32 bins of size 64
1425 16 bins of size 512
1426 8 bins of size 4096
1427 4 bins of size 32768
1428 2 bins of size 262144
1429 1 bin of size what's left
1430
1431 There is actually a little bit of slop in the numbers in bin_index
1432 for the sake of speed. This makes no difference elsewhere.
1433
1434 The special chunks `top' and `last_remainder' get their own bins,
1435 (this is implemented via yet more trickery with the av_ array),
1436 although `top' is never properly linked to its bin since it is
1437 always handled specially.
1438
1439*/
1440
1441#define NAV 128 /* number of bins */
1442
1443typedef struct malloc_chunk* mbinptr;
1444
1445/* access macros */
1446
1447#define bin_at(i) ((mbinptr)((char*)&(av_[2*(i) + 2]) - 2*SIZE_SZ))
1448#define next_bin(b) ((mbinptr)((char*)(b) + 2 * sizeof(mbinptr)))
1449#define prev_bin(b) ((mbinptr)((char*)(b) - 2 * sizeof(mbinptr)))
1450
1451/*
1452 The first 2 bins are never indexed. The corresponding av_ cells are instead
1453 used for bookkeeping. This is not to save space, but to simplify
1454 indexing, maintain locality, and avoid some initialization tests.
1455*/
1456
1457#define top (bin_at(0)->fd) /* The topmost chunk */
1458#define last_remainder (bin_at(1)) /* remainder from last split */
1459
1460
1461/*
1462 Because top initially points to its own bin with initial
1463 zero size, thus forcing extension on the first malloc request,
1464 we avoid having any special code in malloc to check whether
1465 it even exists yet. But we still need to in malloc_extend_top.
1466*/
1467
1468#define initial_top ((mchunkptr)(bin_at(0)))
1469
1470/* Helper macro to initialize bins */
1471
1472#define IAV(i) bin_at(i), bin_at(i)
1473
1474static mbinptr av_[NAV * 2 + 2] = {
1475 0, 0,
1476 IAV(0), IAV(1), IAV(2), IAV(3), IAV(4), IAV(5), IAV(6), IAV(7),
1477 IAV(8), IAV(9), IAV(10), IAV(11), IAV(12), IAV(13), IAV(14), IAV(15),
1478 IAV(16), IAV(17), IAV(18), IAV(19), IAV(20), IAV(21), IAV(22), IAV(23),
1479 IAV(24), IAV(25), IAV(26), IAV(27), IAV(28), IAV(29), IAV(30), IAV(31),
1480 IAV(32), IAV(33), IAV(34), IAV(35), IAV(36), IAV(37), IAV(38), IAV(39),
1481 IAV(40), IAV(41), IAV(42), IAV(43), IAV(44), IAV(45), IAV(46), IAV(47),
1482 IAV(48), IAV(49), IAV(50), IAV(51), IAV(52), IAV(53), IAV(54), IAV(55),
1483 IAV(56), IAV(57), IAV(58), IAV(59), IAV(60), IAV(61), IAV(62), IAV(63),
1484 IAV(64), IAV(65), IAV(66), IAV(67), IAV(68), IAV(69), IAV(70), IAV(71),
1485 IAV(72), IAV(73), IAV(74), IAV(75), IAV(76), IAV(77), IAV(78), IAV(79),
1486 IAV(80), IAV(81), IAV(82), IAV(83), IAV(84), IAV(85), IAV(86), IAV(87),
1487 IAV(88), IAV(89), IAV(90), IAV(91), IAV(92), IAV(93), IAV(94), IAV(95),
1488 IAV(96), IAV(97), IAV(98), IAV(99), IAV(100), IAV(101), IAV(102), IAV(103),
1489 IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111),
1490 IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119),
1491 IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127)
1492};
1493
1494void malloc_bin_reloc (void)
1495{
1496 DECLARE_GLOBAL_DATA_PTR;
1497
1498 unsigned long *p = (unsigned long *)(&av_[2]);
1499 int i;
1500 for (i=2; i<(sizeof(av_)/sizeof(mbinptr)); ++i) {
1501 *p++ += gd->reloc_off;
1502 }
1503}
1504
1505
1506/* field-extraction macros */
1507
1508#define first(b) ((b)->fd)
1509#define last(b) ((b)->bk)
1510
1511/*
1512 Indexing into bins
1513*/
1514
1515#define bin_index(sz) \
1516(((((unsigned long)(sz)) >> 9) == 0) ? (((unsigned long)(sz)) >> 3): \
1517 ((((unsigned long)(sz)) >> 9) <= 4) ? 56 + (((unsigned long)(sz)) >> 6): \
1518 ((((unsigned long)(sz)) >> 9) <= 20) ? 91 + (((unsigned long)(sz)) >> 9): \
1519 ((((unsigned long)(sz)) >> 9) <= 84) ? 110 + (((unsigned long)(sz)) >> 12): \
1520 ((((unsigned long)(sz)) >> 9) <= 340) ? 119 + (((unsigned long)(sz)) >> 15): \
1521 ((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18): \
wdenk8bde7f72003-06-27 21:31:46 +00001522 126)
wdenk217c9da2002-10-25 20:35:49 +00001523/*
1524 bins for chunks < 512 are all spaced 8 bytes apart, and hold
1525 identically sized chunks. This is exploited in malloc.
1526*/
1527
1528#define MAX_SMALLBIN 63
1529#define MAX_SMALLBIN_SIZE 512
1530#define SMALLBIN_WIDTH 8
1531
1532#define smallbin_index(sz) (((unsigned long)(sz)) >> 3)
1533
1534/*
1535 Requests are `small' if both the corresponding and the next bin are small
1536*/
1537
1538#define is_small_request(nb) (nb < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH)
1539
1540
1541
1542/*
1543 To help compensate for the large number of bins, a one-level index
1544 structure is used for bin-by-bin searching. `binblocks' is a
1545 one-word bitvector recording whether groups of BINBLOCKWIDTH bins
1546 have any (possibly) non-empty bins, so they can be skipped over
1547 all at once during during traversals. The bits are NOT always
1548 cleared as soon as all bins in a block are empty, but instead only
1549 when all are noticed to be empty during traversal in malloc.
1550*/
1551
1552#define BINBLOCKWIDTH 4 /* bins per block */
1553
1554#define binblocks (bin_at(0)->size) /* bitvector of nonempty blocks */
1555
1556/* bin<->block macros */
1557
1558#define idx2binblock(ix) ((unsigned)1 << (ix / BINBLOCKWIDTH))
1559#define mark_binblock(ii) (binblocks |= idx2binblock(ii))
1560#define clear_binblock(ii) (binblocks &= ~(idx2binblock(ii)))
1561
1562
1563
1564
1565
1566/* Other static bookkeeping data */
1567
1568/* variables holding tunable values */
1569
1570static unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD;
1571static unsigned long top_pad = DEFAULT_TOP_PAD;
1572static unsigned int n_mmaps_max = DEFAULT_MMAP_MAX;
1573static unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD;
1574
1575/* The first value returned from sbrk */
1576static char* sbrk_base = (char*)(-1);
1577
1578/* The maximum memory obtained from system via sbrk */
1579static unsigned long max_sbrked_mem = 0;
1580
1581/* The maximum via either sbrk or mmap */
1582static unsigned long max_total_mem = 0;
1583
1584/* internal working copy of mallinfo */
1585static struct mallinfo current_mallinfo = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
1586
1587/* The total memory obtained from system via sbrk */
1588#define sbrked_mem (current_mallinfo.arena)
1589
1590/* Tracking mmaps */
1591
1592#if 0
1593static unsigned int n_mmaps = 0;
1594#endif /* 0 */
1595static unsigned long mmapped_mem = 0;
1596#if HAVE_MMAP
1597static unsigned int max_n_mmaps = 0;
1598static unsigned long max_mmapped_mem = 0;
1599#endif
1600
1601
1602
1603/*
1604 Debugging support
1605*/
1606
1607#ifdef DEBUG
1608
1609
1610/*
1611 These routines make a number of assertions about the states
1612 of data structures that should be true at all times. If any
1613 are not true, it's very likely that a user program has somehow
1614 trashed memory. (It's also possible that there is a coding error
1615 in malloc. In which case, please report it!)
1616*/
1617
1618#if __STD_C
1619static void do_check_chunk(mchunkptr p)
1620#else
1621static void do_check_chunk(p) mchunkptr p;
1622#endif
1623{
1624#if 0 /* causes warnings because assert() is off */
1625 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
1626#endif /* 0 */
1627
1628 /* No checkable chunk is mmapped */
1629 assert(!chunk_is_mmapped(p));
1630
1631 /* Check for legal address ... */
1632 assert((char*)p >= sbrk_base);
1633 if (p != top)
1634 assert((char*)p + sz <= (char*)top);
1635 else
1636 assert((char*)p + sz <= sbrk_base + sbrked_mem);
1637
1638}
1639
1640
1641#if __STD_C
1642static void do_check_free_chunk(mchunkptr p)
1643#else
1644static void do_check_free_chunk(p) mchunkptr p;
1645#endif
1646{
1647 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
1648#if 0 /* causes warnings because assert() is off */
1649 mchunkptr next = chunk_at_offset(p, sz);
1650#endif /* 0 */
1651
1652 do_check_chunk(p);
1653
1654 /* Check whether it claims to be free ... */
1655 assert(!inuse(p));
1656
1657 /* Unless a special marker, must have OK fields */
1658 if ((long)sz >= (long)MINSIZE)
1659 {
1660 assert((sz & MALLOC_ALIGN_MASK) == 0);
1661 assert(aligned_OK(chunk2mem(p)));
1662 /* ... matching footer field */
1663 assert(next->prev_size == sz);
1664 /* ... and is fully consolidated */
1665 assert(prev_inuse(p));
1666 assert (next == top || inuse(next));
1667
1668 /* ... and has minimally sane links */
1669 assert(p->fd->bk == p);
1670 assert(p->bk->fd == p);
1671 }
1672 else /* markers are always of size SIZE_SZ */
1673 assert(sz == SIZE_SZ);
1674}
1675
1676#if __STD_C
1677static void do_check_inuse_chunk(mchunkptr p)
1678#else
1679static void do_check_inuse_chunk(p) mchunkptr p;
1680#endif
1681{
1682 mchunkptr next = next_chunk(p);
1683 do_check_chunk(p);
1684
1685 /* Check whether it claims to be in use ... */
1686 assert(inuse(p));
1687
1688 /* ... and is surrounded by OK chunks.
1689 Since more things can be checked with free chunks than inuse ones,
1690 if an inuse chunk borders them and debug is on, it's worth doing them.
1691 */
1692 if (!prev_inuse(p))
1693 {
1694 mchunkptr prv = prev_chunk(p);
1695 assert(next_chunk(prv) == p);
1696 do_check_free_chunk(prv);
1697 }
1698 if (next == top)
1699 {
1700 assert(prev_inuse(next));
1701 assert(chunksize(next) >= MINSIZE);
1702 }
1703 else if (!inuse(next))
1704 do_check_free_chunk(next);
1705
1706}
1707
1708#if __STD_C
1709static void do_check_malloced_chunk(mchunkptr p, INTERNAL_SIZE_T s)
1710#else
1711static void do_check_malloced_chunk(p, s) mchunkptr p; INTERNAL_SIZE_T s;
1712#endif
1713{
1714#if 0 /* causes warnings because assert() is off */
1715 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
1716 long room = sz - s;
1717#endif /* 0 */
1718
1719 do_check_inuse_chunk(p);
1720
1721 /* Legal size ... */
1722 assert((long)sz >= (long)MINSIZE);
1723 assert((sz & MALLOC_ALIGN_MASK) == 0);
1724 assert(room >= 0);
1725 assert(room < (long)MINSIZE);
1726
1727 /* ... and alignment */
1728 assert(aligned_OK(chunk2mem(p)));
1729
1730
1731 /* ... and was allocated at front of an available chunk */
1732 assert(prev_inuse(p));
1733
1734}
1735
1736
1737#define check_free_chunk(P) do_check_free_chunk(P)
1738#define check_inuse_chunk(P) do_check_inuse_chunk(P)
1739#define check_chunk(P) do_check_chunk(P)
1740#define check_malloced_chunk(P,N) do_check_malloced_chunk(P,N)
1741#else
1742#define check_free_chunk(P)
1743#define check_inuse_chunk(P)
1744#define check_chunk(P)
1745#define check_malloced_chunk(P,N)
1746#endif
1747
1748
1749
1750/*
1751 Macro-based internal utilities
1752*/
1753
1754
1755/*
1756 Linking chunks in bin lists.
1757 Call these only with variables, not arbitrary expressions, as arguments.
1758*/
1759
1760/*
1761 Place chunk p of size s in its bin, in size order,
1762 putting it ahead of others of same size.
1763*/
1764
1765
1766#define frontlink(P, S, IDX, BK, FD) \
1767{ \
1768 if (S < MAX_SMALLBIN_SIZE) \
1769 { \
1770 IDX = smallbin_index(S); \
1771 mark_binblock(IDX); \
1772 BK = bin_at(IDX); \
1773 FD = BK->fd; \
1774 P->bk = BK; \
1775 P->fd = FD; \
1776 FD->bk = BK->fd = P; \
1777 } \
1778 else \
1779 { \
1780 IDX = bin_index(S); \
1781 BK = bin_at(IDX); \
1782 FD = BK->fd; \
1783 if (FD == BK) mark_binblock(IDX); \
1784 else \
1785 { \
1786 while (FD != BK && S < chunksize(FD)) FD = FD->fd; \
1787 BK = FD->bk; \
1788 } \
1789 P->bk = BK; \
1790 P->fd = FD; \
1791 FD->bk = BK->fd = P; \
1792 } \
1793}
1794
1795
1796/* take a chunk off a list */
1797
1798#define unlink(P, BK, FD) \
1799{ \
1800 BK = P->bk; \
1801 FD = P->fd; \
1802 FD->bk = BK; \
1803 BK->fd = FD; \
1804} \
1805
1806/* Place p as the last remainder */
1807
1808#define link_last_remainder(P) \
1809{ \
1810 last_remainder->fd = last_remainder->bk = P; \
1811 P->fd = P->bk = last_remainder; \
1812}
1813
1814/* Clear the last_remainder bin */
1815
1816#define clear_last_remainder \
1817 (last_remainder->fd = last_remainder->bk = last_remainder)
1818
1819
wdenk217c9da2002-10-25 20:35:49 +00001820
1821
1822
1823/* Routines dealing with mmap(). */
1824
1825#if HAVE_MMAP
1826
1827#if __STD_C
1828static mchunkptr mmap_chunk(size_t size)
1829#else
1830static mchunkptr mmap_chunk(size) size_t size;
1831#endif
1832{
1833 size_t page_mask = malloc_getpagesize - 1;
1834 mchunkptr p;
1835
1836#ifndef MAP_ANONYMOUS
1837 static int fd = -1;
1838#endif
1839
1840 if(n_mmaps >= n_mmaps_max) return 0; /* too many regions */
1841
1842 /* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because
1843 * there is no following chunk whose prev_size field could be used.
1844 */
1845 size = (size + SIZE_SZ + page_mask) & ~page_mask;
1846
1847#ifdef MAP_ANONYMOUS
1848 p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE,
1849 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
1850#else /* !MAP_ANONYMOUS */
1851 if (fd < 0)
1852 {
1853 fd = open("/dev/zero", O_RDWR);
1854 if(fd < 0) return 0;
1855 }
1856 p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
1857#endif
1858
1859 if(p == (mchunkptr)-1) return 0;
1860
1861 n_mmaps++;
1862 if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps;
1863
1864 /* We demand that eight bytes into a page must be 8-byte aligned. */
1865 assert(aligned_OK(chunk2mem(p)));
1866
1867 /* The offset to the start of the mmapped region is stored
1868 * in the prev_size field of the chunk; normally it is zero,
1869 * but that can be changed in memalign().
1870 */
1871 p->prev_size = 0;
1872 set_head(p, size|IS_MMAPPED);
1873
1874 mmapped_mem += size;
1875 if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
1876 max_mmapped_mem = mmapped_mem;
1877 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
1878 max_total_mem = mmapped_mem + sbrked_mem;
1879 return p;
1880}
1881
1882#if __STD_C
1883static void munmap_chunk(mchunkptr p)
1884#else
1885static void munmap_chunk(p) mchunkptr p;
1886#endif
1887{
1888 INTERNAL_SIZE_T size = chunksize(p);
1889 int ret;
1890
1891 assert (chunk_is_mmapped(p));
1892 assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
1893 assert((n_mmaps > 0));
1894 assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0);
1895
1896 n_mmaps--;
1897 mmapped_mem -= (size + p->prev_size);
1898
1899 ret = munmap((char *)p - p->prev_size, size + p->prev_size);
1900
1901 /* munmap returns non-zero on failure */
1902 assert(ret == 0);
1903}
1904
1905#if HAVE_MREMAP
1906
1907#if __STD_C
1908static mchunkptr mremap_chunk(mchunkptr p, size_t new_size)
1909#else
1910static mchunkptr mremap_chunk(p, new_size) mchunkptr p; size_t new_size;
1911#endif
1912{
1913 size_t page_mask = malloc_getpagesize - 1;
1914 INTERNAL_SIZE_T offset = p->prev_size;
1915 INTERNAL_SIZE_T size = chunksize(p);
1916 char *cp;
1917
1918 assert (chunk_is_mmapped(p));
1919 assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
1920 assert((n_mmaps > 0));
1921 assert(((size + offset) & (malloc_getpagesize-1)) == 0);
1922
1923 /* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
1924 new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask;
1925
1926 cp = (char *)mremap((char *)p - offset, size + offset, new_size, 1);
1927
1928 if (cp == (char *)-1) return 0;
1929
1930 p = (mchunkptr)(cp + offset);
1931
1932 assert(aligned_OK(chunk2mem(p)));
1933
1934 assert((p->prev_size == offset));
1935 set_head(p, (new_size - offset)|IS_MMAPPED);
1936
1937 mmapped_mem -= size + offset;
1938 mmapped_mem += new_size;
1939 if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem)
1940 max_mmapped_mem = mmapped_mem;
1941 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
1942 max_total_mem = mmapped_mem + sbrked_mem;
1943 return p;
1944}
1945
1946#endif /* HAVE_MREMAP */
1947
1948#endif /* HAVE_MMAP */
1949
1950
1951
1952
1953/*
1954 Extend the top-most chunk by obtaining memory from system.
1955 Main interface to sbrk (but see also malloc_trim).
1956*/
1957
1958#if __STD_C
1959static void malloc_extend_top(INTERNAL_SIZE_T nb)
1960#else
1961static void malloc_extend_top(nb) INTERNAL_SIZE_T nb;
1962#endif
1963{
1964 char* brk; /* return value from sbrk */
1965 INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */
1966 INTERNAL_SIZE_T correction; /* bytes for 2nd sbrk call */
1967 char* new_brk; /* return of 2nd sbrk call */
1968 INTERNAL_SIZE_T top_size; /* new size of top chunk */
1969
1970 mchunkptr old_top = top; /* Record state of old top */
1971 INTERNAL_SIZE_T old_top_size = chunksize(old_top);
1972 char* old_end = (char*)(chunk_at_offset(old_top, old_top_size));
1973
1974 /* Pad request with top_pad plus minimal overhead */
1975
1976 INTERNAL_SIZE_T sbrk_size = nb + top_pad + MINSIZE;
1977 unsigned long pagesz = malloc_getpagesize;
1978
1979 /* If not the first time through, round to preserve page boundary */
1980 /* Otherwise, we need to correct to a page size below anyway. */
1981 /* (We also correct below if an intervening foreign sbrk call.) */
1982
1983 if (sbrk_base != (char*)(-1))
1984 sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1);
1985
1986 brk = (char*)(MORECORE (sbrk_size));
1987
1988 /* Fail if sbrk failed or if a foreign sbrk call killed our space */
1989 if (brk == (char*)(MORECORE_FAILURE) ||
1990 (brk < old_end && old_top != initial_top))
1991 return;
1992
1993 sbrked_mem += sbrk_size;
1994
1995 if (brk == old_end) /* can just add bytes to current top */
1996 {
1997 top_size = sbrk_size + old_top_size;
1998 set_head(top, top_size | PREV_INUSE);
1999 }
2000 else
2001 {
2002 if (sbrk_base == (char*)(-1)) /* First time through. Record base */
2003 sbrk_base = brk;
2004 else /* Someone else called sbrk(). Count those bytes as sbrked_mem. */
2005 sbrked_mem += brk - (char*)old_end;
2006
2007 /* Guarantee alignment of first new chunk made from this space */
2008 front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK;
2009 if (front_misalign > 0)
2010 {
2011 correction = (MALLOC_ALIGNMENT) - front_misalign;
2012 brk += correction;
2013 }
2014 else
2015 correction = 0;
2016
2017 /* Guarantee the next brk will be at a page boundary */
2018
2019 correction += ((((unsigned long)(brk + sbrk_size))+(pagesz-1)) &
wdenk8bde7f72003-06-27 21:31:46 +00002020 ~(pagesz - 1)) - ((unsigned long)(brk + sbrk_size));
wdenk217c9da2002-10-25 20:35:49 +00002021
2022 /* Allocate correction */
2023 new_brk = (char*)(MORECORE (correction));
2024 if (new_brk == (char*)(MORECORE_FAILURE)) return;
2025
2026 sbrked_mem += correction;
2027
2028 top = (mchunkptr)brk;
2029 top_size = new_brk - brk + correction;
2030 set_head(top, top_size | PREV_INUSE);
2031
2032 if (old_top != initial_top)
2033 {
2034
2035 /* There must have been an intervening foreign sbrk call. */
2036 /* A double fencepost is necessary to prevent consolidation */
2037
2038 /* If not enough space to do this, then user did something very wrong */
2039 if (old_top_size < MINSIZE)
2040 {
wdenk8bde7f72003-06-27 21:31:46 +00002041 set_head(top, PREV_INUSE); /* will force null return from malloc */
2042 return;
wdenk217c9da2002-10-25 20:35:49 +00002043 }
2044
2045 /* Also keep size a multiple of MALLOC_ALIGNMENT */
2046 old_top_size = (old_top_size - 3*SIZE_SZ) & ~MALLOC_ALIGN_MASK;
2047 set_head_size(old_top, old_top_size);
2048 chunk_at_offset(old_top, old_top_size )->size =
wdenk8bde7f72003-06-27 21:31:46 +00002049 SIZE_SZ|PREV_INUSE;
wdenk217c9da2002-10-25 20:35:49 +00002050 chunk_at_offset(old_top, old_top_size + SIZE_SZ)->size =
wdenk8bde7f72003-06-27 21:31:46 +00002051 SIZE_SZ|PREV_INUSE;
wdenk217c9da2002-10-25 20:35:49 +00002052 /* If possible, release the rest. */
2053 if (old_top_size >= MINSIZE)
wdenk8bde7f72003-06-27 21:31:46 +00002054 fREe(chunk2mem(old_top));
wdenk217c9da2002-10-25 20:35:49 +00002055 }
2056 }
2057
2058 if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem)
2059 max_sbrked_mem = sbrked_mem;
2060 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
2061 max_total_mem = mmapped_mem + sbrked_mem;
2062
2063 /* We always land on a page boundary */
2064 assert(((unsigned long)((char*)top + top_size) & (pagesz - 1)) == 0);
2065}
2066
2067
2068
2069
2070/* Main public routines */
2071
2072
2073/*
2074 Malloc Algorthim:
2075
2076 The requested size is first converted into a usable form, `nb'.
2077 This currently means to add 4 bytes overhead plus possibly more to
2078 obtain 8-byte alignment and/or to obtain a size of at least
2079 MINSIZE (currently 16 bytes), the smallest allocatable size.
2080 (All fits are considered `exact' if they are within MINSIZE bytes.)
2081
2082 From there, the first successful of the following steps is taken:
2083
2084 1. The bin corresponding to the request size is scanned, and if
wdenk8bde7f72003-06-27 21:31:46 +00002085 a chunk of exactly the right size is found, it is taken.
wdenk217c9da2002-10-25 20:35:49 +00002086
2087 2. The most recently remaindered chunk is used if it is big
wdenk8bde7f72003-06-27 21:31:46 +00002088 enough. This is a form of (roving) first fit, used only in
2089 the absence of exact fits. Runs of consecutive requests use
2090 the remainder of the chunk used for the previous such request
2091 whenever possible. This limited use of a first-fit style
2092 allocation strategy tends to give contiguous chunks
2093 coextensive lifetimes, which improves locality and can reduce
2094 fragmentation in the long run.
wdenk217c9da2002-10-25 20:35:49 +00002095
2096 3. Other bins are scanned in increasing size order, using a
wdenk8bde7f72003-06-27 21:31:46 +00002097 chunk big enough to fulfill the request, and splitting off
2098 any remainder. This search is strictly by best-fit; i.e.,
2099 the smallest (with ties going to approximately the least
2100 recently used) chunk that fits is selected.
wdenk217c9da2002-10-25 20:35:49 +00002101
2102 4. If large enough, the chunk bordering the end of memory
wdenk8bde7f72003-06-27 21:31:46 +00002103 (`top') is split off. (This use of `top' is in accord with
2104 the best-fit search rule. In effect, `top' is treated as
2105 larger (and thus less well fitting) than any other available
2106 chunk since it can be extended to be as large as necessary
2107 (up to system limitations).
wdenk217c9da2002-10-25 20:35:49 +00002108
2109 5. If the request size meets the mmap threshold and the
wdenk8bde7f72003-06-27 21:31:46 +00002110 system supports mmap, and there are few enough currently
2111 allocated mmapped regions, and a call to mmap succeeds,
2112 the request is allocated via direct memory mapping.
wdenk217c9da2002-10-25 20:35:49 +00002113
2114 6. Otherwise, the top of memory is extended by
wdenk8bde7f72003-06-27 21:31:46 +00002115 obtaining more space from the system (normally using sbrk,
2116 but definable to anything else via the MORECORE macro).
2117 Memory is gathered from the system (in system page-sized
2118 units) in a way that allows chunks obtained across different
2119 sbrk calls to be consolidated, but does not require
2120 contiguous memory. Thus, it should be safe to intersperse
2121 mallocs with other sbrk calls.
wdenk217c9da2002-10-25 20:35:49 +00002122
2123
2124 All allocations are made from the the `lowest' part of any found
2125 chunk. (The implementation invariant is that prev_inuse is
2126 always true of any allocated chunk; i.e., that each allocated
2127 chunk borders either a previously allocated and still in-use chunk,
2128 or the base of its memory arena.)
2129
2130*/
2131
2132#if __STD_C
2133Void_t* mALLOc(size_t bytes)
2134#else
2135Void_t* mALLOc(bytes) size_t bytes;
2136#endif
2137{
2138 mchunkptr victim; /* inspected/selected chunk */
2139 INTERNAL_SIZE_T victim_size; /* its size */
2140 int idx; /* index for bin traversal */
2141 mbinptr bin; /* associated bin */
2142 mchunkptr remainder; /* remainder from a split */
2143 long remainder_size; /* its size */
2144 int remainder_index; /* its bin index */
2145 unsigned long block; /* block traverser bit */
2146 int startidx; /* first bin of a traversed block */
2147 mchunkptr fwd; /* misc temp for linking */
2148 mchunkptr bck; /* misc temp for linking */
2149 mbinptr q; /* misc temp */
2150
2151 INTERNAL_SIZE_T nb;
2152
2153 if ((long)bytes < 0) return 0;
2154
2155 nb = request2size(bytes); /* padded request size; */
2156
2157 /* Check for exact match in a bin */
2158
2159 if (is_small_request(nb)) /* Faster version for small requests */
2160 {
2161 idx = smallbin_index(nb);
2162
2163 /* No traversal or size check necessary for small bins. */
2164
2165 q = bin_at(idx);
2166 victim = last(q);
2167
2168 /* Also scan the next one, since it would have a remainder < MINSIZE */
2169 if (victim == q)
2170 {
2171 q = next_bin(q);
2172 victim = last(q);
2173 }
2174 if (victim != q)
2175 {
2176 victim_size = chunksize(victim);
2177 unlink(victim, bck, fwd);
2178 set_inuse_bit_at_offset(victim, victim_size);
2179 check_malloced_chunk(victim, nb);
2180 return chunk2mem(victim);
2181 }
2182
2183 idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */
2184
2185 }
2186 else
2187 {
2188 idx = bin_index(nb);
2189 bin = bin_at(idx);
2190
2191 for (victim = last(bin); victim != bin; victim = victim->bk)
2192 {
2193 victim_size = chunksize(victim);
2194 remainder_size = victim_size - nb;
2195
2196 if (remainder_size >= (long)MINSIZE) /* too big */
2197 {
wdenk8bde7f72003-06-27 21:31:46 +00002198 --idx; /* adjust to rescan below after checking last remainder */
2199 break;
wdenk217c9da2002-10-25 20:35:49 +00002200 }
2201
2202 else if (remainder_size >= 0) /* exact fit */
2203 {
wdenk8bde7f72003-06-27 21:31:46 +00002204 unlink(victim, bck, fwd);
2205 set_inuse_bit_at_offset(victim, victim_size);
2206 check_malloced_chunk(victim, nb);
2207 return chunk2mem(victim);
wdenk217c9da2002-10-25 20:35:49 +00002208 }
2209 }
2210
2211 ++idx;
2212
2213 }
2214
2215 /* Try to use the last split-off remainder */
2216
2217 if ( (victim = last_remainder->fd) != last_remainder)
2218 {
2219 victim_size = chunksize(victim);
2220 remainder_size = victim_size - nb;
2221
2222 if (remainder_size >= (long)MINSIZE) /* re-split */
2223 {
2224 remainder = chunk_at_offset(victim, nb);
2225 set_head(victim, nb | PREV_INUSE);
2226 link_last_remainder(remainder);
2227 set_head(remainder, remainder_size | PREV_INUSE);
2228 set_foot(remainder, remainder_size);
2229 check_malloced_chunk(victim, nb);
2230 return chunk2mem(victim);
2231 }
2232
2233 clear_last_remainder;
2234
2235 if (remainder_size >= 0) /* exhaust */
2236 {
2237 set_inuse_bit_at_offset(victim, victim_size);
2238 check_malloced_chunk(victim, nb);
2239 return chunk2mem(victim);
2240 }
2241
2242 /* Else place in bin */
2243
2244 frontlink(victim, victim_size, remainder_index, bck, fwd);
2245 }
2246
2247 /*
2248 If there are any possibly nonempty big-enough blocks,
2249 search for best fitting chunk by scanning bins in blockwidth units.
2250 */
2251
2252 if ( (block = idx2binblock(idx)) <= binblocks)
2253 {
2254
2255 /* Get to the first marked block */
2256
2257 if ( (block & binblocks) == 0)
2258 {
2259 /* force to an even block boundary */
2260 idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH;
2261 block <<= 1;
2262 while ((block & binblocks) == 0)
2263 {
wdenk8bde7f72003-06-27 21:31:46 +00002264 idx += BINBLOCKWIDTH;
2265 block <<= 1;
wdenk217c9da2002-10-25 20:35:49 +00002266 }
2267 }
2268
2269 /* For each possibly nonempty block ... */
2270 for (;;)
2271 {
2272 startidx = idx; /* (track incomplete blocks) */
2273 q = bin = bin_at(idx);
2274
2275 /* For each bin in this block ... */
2276 do
2277 {
wdenk8bde7f72003-06-27 21:31:46 +00002278 /* Find and use first big enough chunk ... */
wdenk217c9da2002-10-25 20:35:49 +00002279
wdenk8bde7f72003-06-27 21:31:46 +00002280 for (victim = last(bin); victim != bin; victim = victim->bk)
2281 {
2282 victim_size = chunksize(victim);
2283 remainder_size = victim_size - nb;
wdenk217c9da2002-10-25 20:35:49 +00002284
wdenk8bde7f72003-06-27 21:31:46 +00002285 if (remainder_size >= (long)MINSIZE) /* split */
2286 {
2287 remainder = chunk_at_offset(victim, nb);
2288 set_head(victim, nb | PREV_INUSE);
2289 unlink(victim, bck, fwd);
2290 link_last_remainder(remainder);
2291 set_head(remainder, remainder_size | PREV_INUSE);
2292 set_foot(remainder, remainder_size);
2293 check_malloced_chunk(victim, nb);
2294 return chunk2mem(victim);
2295 }
wdenk217c9da2002-10-25 20:35:49 +00002296
wdenk8bde7f72003-06-27 21:31:46 +00002297 else if (remainder_size >= 0) /* take */
2298 {
2299 set_inuse_bit_at_offset(victim, victim_size);
2300 unlink(victim, bck, fwd);
2301 check_malloced_chunk(victim, nb);
2302 return chunk2mem(victim);
2303 }
wdenk217c9da2002-10-25 20:35:49 +00002304
wdenk8bde7f72003-06-27 21:31:46 +00002305 }
wdenk217c9da2002-10-25 20:35:49 +00002306
2307 bin = next_bin(bin);
2308
2309 } while ((++idx & (BINBLOCKWIDTH - 1)) != 0);
2310
2311 /* Clear out the block bit. */
2312
2313 do /* Possibly backtrack to try to clear a partial block */
2314 {
wdenk8bde7f72003-06-27 21:31:46 +00002315 if ((startidx & (BINBLOCKWIDTH - 1)) == 0)
2316 {
2317 binblocks &= ~block;
2318 break;
2319 }
2320 --startidx;
wdenk217c9da2002-10-25 20:35:49 +00002321 q = prev_bin(q);
2322 } while (first(q) == q);
2323
2324 /* Get to the next possibly nonempty block */
2325
2326 if ( (block <<= 1) <= binblocks && (block != 0) )
2327 {
wdenk8bde7f72003-06-27 21:31:46 +00002328 while ((block & binblocks) == 0)
2329 {
2330 idx += BINBLOCKWIDTH;
2331 block <<= 1;
2332 }
wdenk217c9da2002-10-25 20:35:49 +00002333 }
2334 else
wdenk8bde7f72003-06-27 21:31:46 +00002335 break;
wdenk217c9da2002-10-25 20:35:49 +00002336 }
2337 }
2338
2339
2340 /* Try to use top chunk */
2341
2342 /* Require that there be a remainder, ensuring top always exists */
2343 if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE)
2344 {
2345
2346#if HAVE_MMAP
2347 /* If big and would otherwise need to extend, try to use mmap instead */
2348 if ((unsigned long)nb >= (unsigned long)mmap_threshold &&
wdenk8bde7f72003-06-27 21:31:46 +00002349 (victim = mmap_chunk(nb)) != 0)
wdenk217c9da2002-10-25 20:35:49 +00002350 return chunk2mem(victim);
2351#endif
2352
2353 /* Try to extend */
2354 malloc_extend_top(nb);
2355 if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE)
2356 return 0; /* propagate failure */
2357 }
2358
2359 victim = top;
2360 set_head(victim, nb | PREV_INUSE);
2361 top = chunk_at_offset(victim, nb);
2362 set_head(top, remainder_size | PREV_INUSE);
2363 check_malloced_chunk(victim, nb);
2364 return chunk2mem(victim);
2365
2366}
2367
2368
2369
2370
2371/*
2372
2373 free() algorithm :
2374
2375 cases:
2376
2377 1. free(0) has no effect.
2378
2379 2. If the chunk was allocated via mmap, it is release via munmap().
2380
2381 3. If a returned chunk borders the current high end of memory,
wdenk8bde7f72003-06-27 21:31:46 +00002382 it is consolidated into the top, and if the total unused
2383 topmost memory exceeds the trim threshold, malloc_trim is
2384 called.
wdenk217c9da2002-10-25 20:35:49 +00002385
2386 4. Other chunks are consolidated as they arrive, and
wdenk8bde7f72003-06-27 21:31:46 +00002387 placed in corresponding bins. (This includes the case of
2388 consolidating with the current `last_remainder').
wdenk217c9da2002-10-25 20:35:49 +00002389
2390*/
2391
2392
2393#if __STD_C
2394void fREe(Void_t* mem)
2395#else
2396void fREe(mem) Void_t* mem;
2397#endif
2398{
2399 mchunkptr p; /* chunk corresponding to mem */
2400 INTERNAL_SIZE_T hd; /* its head field */
2401 INTERNAL_SIZE_T sz; /* its size */
2402 int idx; /* its bin index */
2403 mchunkptr next; /* next contiguous chunk */
2404 INTERNAL_SIZE_T nextsz; /* its size */
2405 INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */
2406 mchunkptr bck; /* misc temp for linking */
2407 mchunkptr fwd; /* misc temp for linking */
2408 int islr; /* track whether merging with last_remainder */
2409
2410 if (mem == 0) /* free(0) has no effect */
2411 return;
2412
2413 p = mem2chunk(mem);
2414 hd = p->size;
2415
2416#if HAVE_MMAP
2417 if (hd & IS_MMAPPED) /* release mmapped memory. */
2418 {
2419 munmap_chunk(p);
2420 return;
2421 }
2422#endif
2423
2424 check_inuse_chunk(p);
2425
2426 sz = hd & ~PREV_INUSE;
2427 next = chunk_at_offset(p, sz);
2428 nextsz = chunksize(next);
2429
2430 if (next == top) /* merge with top */
2431 {
2432 sz += nextsz;
2433
2434 if (!(hd & PREV_INUSE)) /* consolidate backward */
2435 {
2436 prevsz = p->prev_size;
2437 p = chunk_at_offset(p, -((long) prevsz));
2438 sz += prevsz;
2439 unlink(p, bck, fwd);
2440 }
2441
2442 set_head(p, sz | PREV_INUSE);
2443 top = p;
2444 if ((unsigned long)(sz) >= (unsigned long)trim_threshold)
2445 malloc_trim(top_pad);
2446 return;
2447 }
2448
2449 set_head(next, nextsz); /* clear inuse bit */
2450
2451 islr = 0;
2452
2453 if (!(hd & PREV_INUSE)) /* consolidate backward */
2454 {
2455 prevsz = p->prev_size;
2456 p = chunk_at_offset(p, -((long) prevsz));
2457 sz += prevsz;
2458
2459 if (p->fd == last_remainder) /* keep as last_remainder */
2460 islr = 1;
2461 else
2462 unlink(p, bck, fwd);
2463 }
2464
2465 if (!(inuse_bit_at_offset(next, nextsz))) /* consolidate forward */
2466 {
2467 sz += nextsz;
2468
2469 if (!islr && next->fd == last_remainder) /* re-insert last_remainder */
2470 {
2471 islr = 1;
2472 link_last_remainder(p);
2473 }
2474 else
2475 unlink(next, bck, fwd);
2476 }
2477
2478
2479 set_head(p, sz | PREV_INUSE);
2480 set_foot(p, sz);
2481 if (!islr)
2482 frontlink(p, sz, idx, bck, fwd);
2483}
2484
2485
2486
2487
2488
2489/*
2490
2491 Realloc algorithm:
2492
2493 Chunks that were obtained via mmap cannot be extended or shrunk
2494 unless HAVE_MREMAP is defined, in which case mremap is used.
2495 Otherwise, if their reallocation is for additional space, they are
2496 copied. If for less, they are just left alone.
2497
2498 Otherwise, if the reallocation is for additional space, and the
2499 chunk can be extended, it is, else a malloc-copy-free sequence is
2500 taken. There are several different ways that a chunk could be
2501 extended. All are tried:
2502
2503 * Extending forward into following adjacent free chunk.
2504 * Shifting backwards, joining preceding adjacent space
2505 * Both shifting backwards and extending forward.
2506 * Extending into newly sbrked space
2507
2508 Unless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with a
2509 size argument of zero (re)allocates a minimum-sized chunk.
2510
2511 If the reallocation is for less space, and the new request is for
2512 a `small' (<512 bytes) size, then the newly unused space is lopped
2513 off and freed.
2514
2515 The old unix realloc convention of allowing the last-free'd chunk
2516 to be used as an argument to realloc is no longer supported.
2517 I don't know of any programs still relying on this feature,
2518 and allowing it would also allow too many other incorrect
2519 usages of realloc to be sensible.
2520
2521
2522*/
2523
2524
2525#if __STD_C
2526Void_t* rEALLOc(Void_t* oldmem, size_t bytes)
2527#else
2528Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes;
2529#endif
2530{
2531 INTERNAL_SIZE_T nb; /* padded request size */
2532
2533 mchunkptr oldp; /* chunk corresponding to oldmem */
2534 INTERNAL_SIZE_T oldsize; /* its size */
2535
2536 mchunkptr newp; /* chunk to return */
2537 INTERNAL_SIZE_T newsize; /* its size */
2538 Void_t* newmem; /* corresponding user mem */
2539
2540 mchunkptr next; /* next contiguous chunk after oldp */
2541 INTERNAL_SIZE_T nextsize; /* its size */
2542
2543 mchunkptr prev; /* previous contiguous chunk before oldp */
2544 INTERNAL_SIZE_T prevsize; /* its size */
2545
2546 mchunkptr remainder; /* holds split off extra space from newp */
2547 INTERNAL_SIZE_T remainder_size; /* its size */
2548
2549 mchunkptr bck; /* misc temp for linking */
2550 mchunkptr fwd; /* misc temp for linking */
2551
2552#ifdef REALLOC_ZERO_BYTES_FREES
2553 if (bytes == 0) { fREe(oldmem); return 0; }
2554#endif
2555
2556 if ((long)bytes < 0) return 0;
2557
2558 /* realloc of null is supposed to be same as malloc */
2559 if (oldmem == 0) return mALLOc(bytes);
2560
2561 newp = oldp = mem2chunk(oldmem);
2562 newsize = oldsize = chunksize(oldp);
2563
2564
2565 nb = request2size(bytes);
2566
2567#if HAVE_MMAP
2568 if (chunk_is_mmapped(oldp))
2569 {
2570#if HAVE_MREMAP
2571 newp = mremap_chunk(oldp, nb);
2572 if(newp) return chunk2mem(newp);
2573#endif
2574 /* Note the extra SIZE_SZ overhead. */
2575 if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing */
2576 /* Must alloc, copy, free. */
2577 newmem = mALLOc(bytes);
2578 if (newmem == 0) return 0; /* propagate failure */
2579 MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ);
2580 munmap_chunk(oldp);
2581 return newmem;
2582 }
2583#endif
2584
2585 check_inuse_chunk(oldp);
2586
2587 if ((long)(oldsize) < (long)(nb))
2588 {
2589
2590 /* Try expanding forward */
2591
2592 next = chunk_at_offset(oldp, oldsize);
2593 if (next == top || !inuse(next))
2594 {
2595 nextsize = chunksize(next);
2596
2597 /* Forward into top only if a remainder */
2598 if (next == top)
2599 {
wdenk8bde7f72003-06-27 21:31:46 +00002600 if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE))
2601 {
2602 newsize += nextsize;
2603 top = chunk_at_offset(oldp, nb);
2604 set_head(top, (newsize - nb) | PREV_INUSE);
2605 set_head_size(oldp, nb);
2606 return chunk2mem(oldp);
2607 }
wdenk217c9da2002-10-25 20:35:49 +00002608 }
2609
2610 /* Forward into next chunk */
2611 else if (((long)(nextsize + newsize) >= (long)(nb)))
2612 {
wdenk8bde7f72003-06-27 21:31:46 +00002613 unlink(next, bck, fwd);
2614 newsize += nextsize;
2615 goto split;
wdenk217c9da2002-10-25 20:35:49 +00002616 }
2617 }
2618 else
2619 {
2620 next = 0;
2621 nextsize = 0;
2622 }
2623
2624 /* Try shifting backwards. */
2625
2626 if (!prev_inuse(oldp))
2627 {
2628 prev = prev_chunk(oldp);
2629 prevsize = chunksize(prev);
2630
2631 /* try forward + backward first to save a later consolidation */
2632
2633 if (next != 0)
2634 {
wdenk8bde7f72003-06-27 21:31:46 +00002635 /* into top */
2636 if (next == top)
2637 {
2638 if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE))
2639 {
2640 unlink(prev, bck, fwd);
2641 newp = prev;
2642 newsize += prevsize + nextsize;
2643 newmem = chunk2mem(newp);
2644 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
2645 top = chunk_at_offset(newp, nb);
2646 set_head(top, (newsize - nb) | PREV_INUSE);
2647 set_head_size(newp, nb);
2648 return newmem;
2649 }
2650 }
wdenk217c9da2002-10-25 20:35:49 +00002651
wdenk8bde7f72003-06-27 21:31:46 +00002652 /* into next chunk */
2653 else if (((long)(nextsize + prevsize + newsize) >= (long)(nb)))
2654 {
2655 unlink(next, bck, fwd);
2656 unlink(prev, bck, fwd);
2657 newp = prev;
2658 newsize += nextsize + prevsize;
2659 newmem = chunk2mem(newp);
2660 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
2661 goto split;
2662 }
wdenk217c9da2002-10-25 20:35:49 +00002663 }
2664
2665 /* backward only */
2666 if (prev != 0 && (long)(prevsize + newsize) >= (long)nb)
2667 {
wdenk8bde7f72003-06-27 21:31:46 +00002668 unlink(prev, bck, fwd);
2669 newp = prev;
2670 newsize += prevsize;
2671 newmem = chunk2mem(newp);
2672 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
2673 goto split;
wdenk217c9da2002-10-25 20:35:49 +00002674 }
2675 }
2676
2677 /* Must allocate */
2678
2679 newmem = mALLOc (bytes);
2680
2681 if (newmem == 0) /* propagate failure */
2682 return 0;
2683
2684 /* Avoid copy if newp is next chunk after oldp. */
2685 /* (This can only happen when new chunk is sbrk'ed.) */
2686
2687 if ( (newp = mem2chunk(newmem)) == next_chunk(oldp))
2688 {
2689 newsize += chunksize(newp);
2690 newp = oldp;
2691 goto split;
2692 }
2693
2694 /* Otherwise copy, free, and exit */
2695 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
2696 fREe(oldmem);
2697 return newmem;
2698 }
2699
2700
2701 split: /* split off extra room in old or expanded chunk */
2702
2703 if (newsize - nb >= MINSIZE) /* split off remainder */
2704 {
2705 remainder = chunk_at_offset(newp, nb);
2706 remainder_size = newsize - nb;
2707 set_head_size(newp, nb);
2708 set_head(remainder, remainder_size | PREV_INUSE);
2709 set_inuse_bit_at_offset(remainder, remainder_size);
2710 fREe(chunk2mem(remainder)); /* let free() deal with it */
2711 }
2712 else
2713 {
2714 set_head_size(newp, newsize);
2715 set_inuse_bit_at_offset(newp, newsize);
2716 }
2717
2718 check_inuse_chunk(newp);
2719 return chunk2mem(newp);
2720}
2721
2722
2723
2724
2725/*
2726
2727 memalign algorithm:
2728
2729 memalign requests more than enough space from malloc, finds a spot
2730 within that chunk that meets the alignment request, and then
2731 possibly frees the leading and trailing space.
2732
2733 The alignment argument must be a power of two. This property is not
2734 checked by memalign, so misuse may result in random runtime errors.
2735
2736 8-byte alignment is guaranteed by normal malloc calls, so don't
2737 bother calling memalign with an argument of 8 or less.
2738
2739 Overreliance on memalign is a sure way to fragment space.
2740
2741*/
2742
2743
2744#if __STD_C
2745Void_t* mEMALIGn(size_t alignment, size_t bytes)
2746#else
2747Void_t* mEMALIGn(alignment, bytes) size_t alignment; size_t bytes;
2748#endif
2749{
2750 INTERNAL_SIZE_T nb; /* padded request size */
2751 char* m; /* memory returned by malloc call */
2752 mchunkptr p; /* corresponding chunk */
2753 char* brk; /* alignment point within p */
2754 mchunkptr newp; /* chunk to return */
2755 INTERNAL_SIZE_T newsize; /* its size */
2756 INTERNAL_SIZE_T leadsize; /* leading space befor alignment point */
2757 mchunkptr remainder; /* spare room at end to split off */
2758 long remainder_size; /* its size */
2759
2760 if ((long)bytes < 0) return 0;
2761
2762 /* If need less alignment than we give anyway, just relay to malloc */
2763
2764 if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes);
2765
2766 /* Otherwise, ensure that it is at least a minimum chunk size */
2767
2768 if (alignment < MINSIZE) alignment = MINSIZE;
2769
2770 /* Call malloc with worst case padding to hit alignment. */
2771
2772 nb = request2size(bytes);
2773 m = (char*)(mALLOc(nb + alignment + MINSIZE));
2774
2775 if (m == 0) return 0; /* propagate failure */
2776
2777 p = mem2chunk(m);
2778
2779 if ((((unsigned long)(m)) % alignment) == 0) /* aligned */
2780 {
2781#if HAVE_MMAP
2782 if(chunk_is_mmapped(p))
2783 return chunk2mem(p); /* nothing more to do */
2784#endif
2785 }
2786 else /* misaligned */
2787 {
2788 /*
2789 Find an aligned spot inside chunk.
2790 Since we need to give back leading space in a chunk of at
2791 least MINSIZE, if the first calculation places us at
2792 a spot with less than MINSIZE leader, we can move to the
2793 next aligned spot -- we've allocated enough total room so that
2794 this is always possible.
2795 */
2796
2797 brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) & -((signed) alignment));
2798 if ((long)(brk - (char*)(p)) < MINSIZE) brk = brk + alignment;
2799
2800 newp = (mchunkptr)brk;
2801 leadsize = brk - (char*)(p);
2802 newsize = chunksize(p) - leadsize;
2803
2804#if HAVE_MMAP
2805 if(chunk_is_mmapped(p))
2806 {
2807 newp->prev_size = p->prev_size + leadsize;
2808 set_head(newp, newsize|IS_MMAPPED);
2809 return chunk2mem(newp);
2810 }
2811#endif
2812
2813 /* give back leader, use the rest */
2814
2815 set_head(newp, newsize | PREV_INUSE);
2816 set_inuse_bit_at_offset(newp, newsize);
2817 set_head_size(p, leadsize);
2818 fREe(chunk2mem(p));
2819 p = newp;
2820
2821 assert (newsize >= nb && (((unsigned long)(chunk2mem(p))) % alignment) == 0);
2822 }
2823
2824 /* Also give back spare room at the end */
2825
2826 remainder_size = chunksize(p) - nb;
2827
2828 if (remainder_size >= (long)MINSIZE)
2829 {
2830 remainder = chunk_at_offset(p, nb);
2831 set_head(remainder, remainder_size | PREV_INUSE);
2832 set_head_size(p, nb);
2833 fREe(chunk2mem(remainder));
2834 }
2835
2836 check_inuse_chunk(p);
2837 return chunk2mem(p);
2838
2839}
2840
2841
2842
2843
2844/*
2845 valloc just invokes memalign with alignment argument equal
2846 to the page size of the system (or as near to this as can
2847 be figured out from all the includes/defines above.)
2848*/
2849
2850#if __STD_C
2851Void_t* vALLOc(size_t bytes)
2852#else
2853Void_t* vALLOc(bytes) size_t bytes;
2854#endif
2855{
2856 return mEMALIGn (malloc_getpagesize, bytes);
2857}
2858
2859/*
2860 pvalloc just invokes valloc for the nearest pagesize
2861 that will accommodate request
2862*/
2863
2864
2865#if __STD_C
2866Void_t* pvALLOc(size_t bytes)
2867#else
2868Void_t* pvALLOc(bytes) size_t bytes;
2869#endif
2870{
2871 size_t pagesize = malloc_getpagesize;
2872 return mEMALIGn (pagesize, (bytes + pagesize - 1) & ~(pagesize - 1));
2873}
2874
2875/*
2876
2877 calloc calls malloc, then zeroes out the allocated chunk.
2878
2879*/
2880
2881#if __STD_C
2882Void_t* cALLOc(size_t n, size_t elem_size)
2883#else
2884Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size;
2885#endif
2886{
2887 mchunkptr p;
2888 INTERNAL_SIZE_T csz;
2889
2890 INTERNAL_SIZE_T sz = n * elem_size;
2891
2892
2893 /* check if expand_top called, in which case don't need to clear */
2894#if MORECORE_CLEARS
2895 mchunkptr oldtop = top;
2896 INTERNAL_SIZE_T oldtopsize = chunksize(top);
2897#endif
2898 Void_t* mem = mALLOc (sz);
2899
2900 if ((long)n < 0) return 0;
2901
2902 if (mem == 0)
2903 return 0;
2904 else
2905 {
2906 p = mem2chunk(mem);
2907
2908 /* Two optional cases in which clearing not necessary */
2909
2910
2911#if HAVE_MMAP
2912 if (chunk_is_mmapped(p)) return mem;
2913#endif
2914
2915 csz = chunksize(p);
2916
2917#if MORECORE_CLEARS
2918 if (p == oldtop && csz > oldtopsize)
2919 {
2920 /* clear only the bytes from non-freshly-sbrked memory */
2921 csz = oldtopsize;
2922 }
2923#endif
2924
2925 MALLOC_ZERO(mem, csz - SIZE_SZ);
2926 return mem;
2927 }
2928}
2929
2930/*
2931
2932 cfree just calls free. It is needed/defined on some systems
2933 that pair it with calloc, presumably for odd historical reasons.
2934
2935*/
2936
2937#if !defined(INTERNAL_LINUX_C_LIB) || !defined(__ELF__)
2938#if __STD_C
2939void cfree(Void_t *mem)
2940#else
2941void cfree(mem) Void_t *mem;
2942#endif
2943{
2944 fREe(mem);
2945}
2946#endif
2947
2948
2949
2950/*
2951
2952 Malloc_trim gives memory back to the system (via negative
2953 arguments to sbrk) if there is unused memory at the `high' end of
2954 the malloc pool. You can call this after freeing large blocks of
2955 memory to potentially reduce the system-level memory requirements
2956 of a program. However, it cannot guarantee to reduce memory. Under
2957 some allocation patterns, some large free blocks of memory will be
2958 locked between two used chunks, so they cannot be given back to
2959 the system.
2960
2961 The `pad' argument to malloc_trim represents the amount of free
2962 trailing space to leave untrimmed. If this argument is zero,
2963 only the minimum amount of memory to maintain internal data
2964 structures will be left (one page or less). Non-zero arguments
2965 can be supplied to maintain enough trailing space to service
2966 future expected allocations without having to re-obtain memory
2967 from the system.
2968
2969 Malloc_trim returns 1 if it actually released any memory, else 0.
2970
2971*/
2972
2973#if __STD_C
2974int malloc_trim(size_t pad)
2975#else
2976int malloc_trim(pad) size_t pad;
2977#endif
2978{
2979 long top_size; /* Amount of top-most memory */
2980 long extra; /* Amount to release */
2981 char* current_brk; /* address returned by pre-check sbrk call */
2982 char* new_brk; /* address returned by negative sbrk call */
2983
2984 unsigned long pagesz = malloc_getpagesize;
2985
2986 top_size = chunksize(top);
2987 extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz;
2988
2989 if (extra < (long)pagesz) /* Not enough memory to release */
2990 return 0;
2991
2992 else
2993 {
2994 /* Test to make sure no one else called sbrk */
2995 current_brk = (char*)(MORECORE (0));
2996 if (current_brk != (char*)(top) + top_size)
2997 return 0; /* Apparently we don't own memory; must fail */
2998
2999 else
3000 {
3001 new_brk = (char*)(MORECORE (-extra));
3002
3003 if (new_brk == (char*)(MORECORE_FAILURE)) /* sbrk failed? */
3004 {
wdenk8bde7f72003-06-27 21:31:46 +00003005 /* Try to figure out what we have */
3006 current_brk = (char*)(MORECORE (0));
3007 top_size = current_brk - (char*)top;
3008 if (top_size >= (long)MINSIZE) /* if not, we are very very dead! */
3009 {
3010 sbrked_mem = current_brk - sbrk_base;
3011 set_head(top, top_size | PREV_INUSE);
3012 }
3013 check_chunk(top);
3014 return 0;
wdenk217c9da2002-10-25 20:35:49 +00003015 }
3016
3017 else
3018 {
wdenk8bde7f72003-06-27 21:31:46 +00003019 /* Success. Adjust top accordingly. */
3020 set_head(top, (top_size - extra) | PREV_INUSE);
3021 sbrked_mem -= extra;
3022 check_chunk(top);
3023 return 1;
wdenk217c9da2002-10-25 20:35:49 +00003024 }
3025 }
3026 }
3027}
3028
3029
3030
3031/*
3032 malloc_usable_size:
3033
3034 This routine tells you how many bytes you can actually use in an
3035 allocated chunk, which may be more than you requested (although
3036 often not). You can use this many bytes without worrying about
3037 overwriting other allocated objects. Not a particularly great
3038 programming practice, but still sometimes useful.
3039
3040*/
3041
3042#if __STD_C
3043size_t malloc_usable_size(Void_t* mem)
3044#else
3045size_t malloc_usable_size(mem) Void_t* mem;
3046#endif
3047{
3048 mchunkptr p;
3049 if (mem == 0)
3050 return 0;
3051 else
3052 {
3053 p = mem2chunk(mem);
3054 if(!chunk_is_mmapped(p))
3055 {
3056 if (!inuse(p)) return 0;
3057 check_inuse_chunk(p);
3058 return chunksize(p) - SIZE_SZ;
3059 }
3060 return chunksize(p) - 2*SIZE_SZ;
3061 }
3062}
3063
3064
3065
3066
3067/* Utility to update current_mallinfo for malloc_stats and mallinfo() */
3068
3069#if 0
3070static void malloc_update_mallinfo()
3071{
3072 int i;
3073 mbinptr b;
3074 mchunkptr p;
3075#ifdef DEBUG
3076 mchunkptr q;
3077#endif
3078
3079 INTERNAL_SIZE_T avail = chunksize(top);
3080 int navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0;
3081
3082 for (i = 1; i < NAV; ++i)
3083 {
3084 b = bin_at(i);
3085 for (p = last(b); p != b; p = p->bk)
3086 {
3087#ifdef DEBUG
3088 check_free_chunk(p);
3089 for (q = next_chunk(p);
wdenk8bde7f72003-06-27 21:31:46 +00003090 q < top && inuse(q) && (long)(chunksize(q)) >= (long)MINSIZE;
3091 q = next_chunk(q))
3092 check_inuse_chunk(q);
wdenk217c9da2002-10-25 20:35:49 +00003093#endif
3094 avail += chunksize(p);
3095 navail++;
3096 }
3097 }
3098
3099 current_mallinfo.ordblks = navail;
3100 current_mallinfo.uordblks = sbrked_mem - avail;
3101 current_mallinfo.fordblks = avail;
3102 current_mallinfo.hblks = n_mmaps;
3103 current_mallinfo.hblkhd = mmapped_mem;
3104 current_mallinfo.keepcost = chunksize(top);
3105
3106}
3107#endif /* 0 */
3108
3109
3110
3111/*
3112
3113 malloc_stats:
3114
3115 Prints on the amount of space obtain from the system (both
3116 via sbrk and mmap), the maximum amount (which may be more than
3117 current if malloc_trim and/or munmap got called), the maximum
3118 number of simultaneous mmap regions used, and the current number
3119 of bytes allocated via malloc (or realloc, etc) but not yet
3120 freed. (Note that this is the number of bytes allocated, not the
3121 number requested. It will be larger than the number requested
3122 because of alignment and bookkeeping overhead.)
3123
3124*/
3125
3126#if 0
3127void malloc_stats()
3128{
3129 malloc_update_mallinfo();
3130 printf("max system bytes = %10u\n",
wdenk8bde7f72003-06-27 21:31:46 +00003131 (unsigned int)(max_total_mem));
wdenk217c9da2002-10-25 20:35:49 +00003132 printf("system bytes = %10u\n",
wdenk8bde7f72003-06-27 21:31:46 +00003133 (unsigned int)(sbrked_mem + mmapped_mem));
wdenk217c9da2002-10-25 20:35:49 +00003134 printf("in use bytes = %10u\n",
wdenk8bde7f72003-06-27 21:31:46 +00003135 (unsigned int)(current_mallinfo.uordblks + mmapped_mem));
wdenk217c9da2002-10-25 20:35:49 +00003136#if HAVE_MMAP
3137 printf("max mmap regions = %10u\n",
wdenk8bde7f72003-06-27 21:31:46 +00003138 (unsigned int)max_n_mmaps);
wdenk217c9da2002-10-25 20:35:49 +00003139#endif
3140}
3141#endif /* 0 */
3142
3143/*
3144 mallinfo returns a copy of updated current mallinfo.
3145*/
3146
3147#if 0
3148struct mallinfo mALLINFo()
3149{
3150 malloc_update_mallinfo();
3151 return current_mallinfo;
3152}
3153#endif /* 0 */
3154
3155
3156
3157
3158/*
3159 mallopt:
3160
3161 mallopt is the general SVID/XPG interface to tunable parameters.
3162 The format is to provide a (parameter-number, parameter-value) pair.
3163 mallopt then sets the corresponding parameter to the argument
3164 value if it can (i.e., so long as the value is meaningful),
3165 and returns 1 if successful else 0.
3166
3167 See descriptions of tunable parameters above.
3168
3169*/
3170
3171#if __STD_C
3172int mALLOPt(int param_number, int value)
3173#else
3174int mALLOPt(param_number, value) int param_number; int value;
3175#endif
3176{
3177 switch(param_number)
3178 {
3179 case M_TRIM_THRESHOLD:
3180 trim_threshold = value; return 1;
3181 case M_TOP_PAD:
3182 top_pad = value; return 1;
3183 case M_MMAP_THRESHOLD:
3184 mmap_threshold = value; return 1;
3185 case M_MMAP_MAX:
3186#if HAVE_MMAP
3187 n_mmaps_max = value; return 1;
3188#else
3189 if (value != 0) return 0; else n_mmaps_max = value; return 1;
3190#endif
3191
3192 default:
3193 return 0;
3194 }
3195}
3196
3197/*
3198
3199History:
3200
3201 V2.6.6 Sun Dec 5 07:42:19 1999 Doug Lea (dl at gee)
3202 * return null for negative arguments
3203 * Added Several WIN32 cleanups from Martin C. Fong <mcfong@yahoo.com>
wdenk8bde7f72003-06-27 21:31:46 +00003204 * Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h'
3205 (e.g. WIN32 platforms)
3206 * Cleanup up header file inclusion for WIN32 platforms
3207 * Cleanup code to avoid Microsoft Visual C++ compiler complaints
3208 * Add 'USE_DL_PREFIX' to quickly allow co-existence with existing
3209 memory allocation routines
3210 * Set 'malloc_getpagesize' for WIN32 platforms (needs more work)
3211 * Use 'assert' rather than 'ASSERT' in WIN32 code to conform to
wdenk217c9da2002-10-25 20:35:49 +00003212 usage of 'assert' in non-WIN32 code
wdenk8bde7f72003-06-27 21:31:46 +00003213 * Improve WIN32 'sbrk()' emulation's 'findRegion()' routine to
3214 avoid infinite loop
wdenk217c9da2002-10-25 20:35:49 +00003215 * Always call 'fREe()' rather than 'free()'
3216
3217 V2.6.5 Wed Jun 17 15:57:31 1998 Doug Lea (dl at gee)
3218 * Fixed ordering problem with boundary-stamping
3219
3220 V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee)
3221 * Added pvalloc, as recommended by H.J. Liu
3222 * Added 64bit pointer support mainly from Wolfram Gloger
3223 * Added anonymously donated WIN32 sbrk emulation
3224 * Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen
3225 * malloc_extend_top: fix mask error that caused wastage after
wdenk8bde7f72003-06-27 21:31:46 +00003226 foreign sbrks
wdenk217c9da2002-10-25 20:35:49 +00003227 * Add linux mremap support code from HJ Liu
3228
3229 V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee)
3230 * Integrated most documentation with the code.
3231 * Add support for mmap, with help from
wdenk8bde7f72003-06-27 21:31:46 +00003232 Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
wdenk217c9da2002-10-25 20:35:49 +00003233 * Use last_remainder in more cases.
3234 * Pack bins using idea from colin@nyx10.cs.du.edu
3235 * Use ordered bins instead of best-fit threshhold
3236 * Eliminate block-local decls to simplify tracing and debugging.
3237 * Support another case of realloc via move into top
3238 * Fix error occuring when initial sbrk_base not word-aligned.
3239 * Rely on page size for units instead of SBRK_UNIT to
wdenk8bde7f72003-06-27 21:31:46 +00003240 avoid surprises about sbrk alignment conventions.
wdenk217c9da2002-10-25 20:35:49 +00003241 * Add mallinfo, mallopt. Thanks to Raymond Nijssen
wdenk8bde7f72003-06-27 21:31:46 +00003242 (raymond@es.ele.tue.nl) for the suggestion.
wdenk217c9da2002-10-25 20:35:49 +00003243 * Add `pad' argument to malloc_trim and top_pad mallopt parameter.
3244 * More precautions for cases where other routines call sbrk,
wdenk8bde7f72003-06-27 21:31:46 +00003245 courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
wdenk217c9da2002-10-25 20:35:49 +00003246 * Added macros etc., allowing use in linux libc from
wdenk8bde7f72003-06-27 21:31:46 +00003247 H.J. Lu (hjl@gnu.ai.mit.edu)
wdenk217c9da2002-10-25 20:35:49 +00003248 * Inverted this history list
3249
3250 V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee)
3251 * Re-tuned and fixed to behave more nicely with V2.6.0 changes.
3252 * Removed all preallocation code since under current scheme
wdenk8bde7f72003-06-27 21:31:46 +00003253 the work required to undo bad preallocations exceeds
3254 the work saved in good cases for most test programs.
wdenk217c9da2002-10-25 20:35:49 +00003255 * No longer use return list or unconsolidated bins since
wdenk8bde7f72003-06-27 21:31:46 +00003256 no scheme using them consistently outperforms those that don't
3257 given above changes.
wdenk217c9da2002-10-25 20:35:49 +00003258 * Use best fit for very large chunks to prevent some worst-cases.
3259 * Added some support for debugging
3260
3261 V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee)
3262 * Removed footers when chunks are in use. Thanks to
wdenk8bde7f72003-06-27 21:31:46 +00003263 Paul Wilson (wilson@cs.texas.edu) for the suggestion.
wdenk217c9da2002-10-25 20:35:49 +00003264
3265 V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee)
3266 * Added malloc_trim, with help from Wolfram Gloger
wdenk8bde7f72003-06-27 21:31:46 +00003267 (wmglo@Dent.MED.Uni-Muenchen.DE).
wdenk217c9da2002-10-25 20:35:49 +00003268
3269 V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g)
3270
3271 V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g)
3272 * realloc: try to expand in both directions
3273 * malloc: swap order of clean-bin strategy;
3274 * realloc: only conditionally expand backwards
3275 * Try not to scavenge used bins
3276 * Use bin counts as a guide to preallocation
3277 * Occasionally bin return list chunks in first scan
3278 * Add a few optimizations from colin@nyx10.cs.du.edu
3279
3280 V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g)
3281 * faster bin computation & slightly different binning
3282 * merged all consolidations to one part of malloc proper
wdenk8bde7f72003-06-27 21:31:46 +00003283 (eliminating old malloc_find_space & malloc_clean_bin)
wdenk217c9da2002-10-25 20:35:49 +00003284 * Scan 2 returns chunks (not just 1)
3285 * Propagate failure in realloc if malloc returns 0
3286 * Add stuff to allow compilation on non-ANSI compilers
wdenk8bde7f72003-06-27 21:31:46 +00003287 from kpv@research.att.com
wdenk217c9da2002-10-25 20:35:49 +00003288
3289 V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu)
3290 * removed potential for odd address access in prev_chunk
3291 * removed dependency on getpagesize.h
3292 * misc cosmetics and a bit more internal documentation
3293 * anticosmetics: mangled names in macros to evade debugger strangeness
3294 * tested on sparc, hp-700, dec-mips, rs6000
wdenk8bde7f72003-06-27 21:31:46 +00003295 with gcc & native cc (hp, dec only) allowing
3296 Detlefs & Zorn comparison study (in SIGPLAN Notices.)
wdenk217c9da2002-10-25 20:35:49 +00003297
3298 Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu)
3299 * Based loosely on libg++-1.2X malloc. (It retains some of the overall
wdenk8bde7f72003-06-27 21:31:46 +00003300 structure of old version, but most details differ.)
wdenk217c9da2002-10-25 20:35:49 +00003301
3302*/