source: SVN/cambria/redboot/packages/services/memalloc/common/current/doc/dlmalloc/dlmalloc-2.6.6.c @ 1

Last change on this file since 1 was 1, checked in by Tim Harvey, 2 years ago

restored latest version of files from server backup

Signed-off-by: Tim Harvey <tharvey@…>

File size: 102.0 KB
Line 
1/* ---------- To make a malloc.h, start cutting here ------------ */
2
3/*
4  A version of malloc/free/realloc written by Doug Lea and released to the
5  public domain.  Send questions/comments/complaints/performance data
6  to dl@cs.oswego.edu
7
8* VERSION 2.6.6  Sun Mar  5 19:10:03 2000  Doug Lea  (dl at gee)
9 
10   Note: There may be an updated version of this malloc obtainable at
11           ftp://g.oswego.edu/pub/misc/malloc.c
12         Check before installing!
13
14* Why use this malloc?
15
16  This is not the fastest, most space-conserving, most portable, or
17  most tunable malloc ever written. However it is among the fastest
18  while also being among the most space-conserving, portable and tunable.
19  Consistent balance across these factors results in a good general-purpose
20  allocator. For a high-level description, see
21     http://g.oswego.edu/dl/html/malloc.html
22
23* Synopsis of public routines
24
25  (Much fuller descriptions are contained in the program documentation below.)
26
27  malloc(size_t n);
28     Return a pointer to a newly allocated chunk of at least n bytes, or null
29     if no space is available.
30  free(Void_t* p);
31     Release the chunk of memory pointed to by p, or no effect if p is null.
32  realloc(Void_t* p, size_t n);
33     Return a pointer to a chunk of size n that contains the same data
34     as does chunk p up to the minimum of (n, p's size) bytes, or null
35     if no space is available. The returned pointer may or may not be
36     the same as p. If p is null, equivalent to malloc.  Unless the
37     #define REALLOC_ZERO_BYTES_FREES below is set, realloc with a
38     size argument of zero (re)allocates a minimum-sized chunk.
39  memalign(size_t alignment, size_t n);
40     Return a pointer to a newly allocated chunk of n bytes, aligned
41     in accord with the alignment argument, which must be a power of
42     two.
43  valloc(size_t n);
44     Equivalent to memalign(pagesize, n), where pagesize is the page
45     size of the system (or as near to this as can be figured out from
46     all the includes/defines below.)
47  pvalloc(size_t n);
48     Equivalent to valloc(minimum-page-that-holds(n)), that is,
49     round up n to nearest pagesize.
50  calloc(size_t unit, size_t quantity);
51     Returns a pointer to quantity * unit bytes, with all locations
52     set to zero.
53  cfree(Void_t* p);
54     Equivalent to free(p).
55  malloc_trim(size_t pad);
56     Release all but pad bytes of freed top-most memory back
57     to the system. Return 1 if successful, else 0.
58  malloc_usable_size(Void_t* p);
59     Report the number usable allocated bytes associated with allocated
60     chunk p. This may or may not report more bytes than were requested,
61     due to alignment and minimum size constraints.
62  malloc_stats();
63     Prints brief summary statistics on stderr.
64  mallinfo()
65     Returns (by copy) a struct containing various summary statistics.
66  mallopt(int parameter_number, int parameter_value)
67     Changes one of the tunable parameters described below. Returns
68     1 if successful in changing the parameter, else 0.
69
70* Vital statistics:
71
72  Alignment:                            8-byte
73       8 byte alignment is currently hardwired into the design.  This
74       seems to suffice for all current machines and C compilers.
75
76  Assumed pointer representation:       4 or 8 bytes
77       Code for 8-byte pointers is untested by me but has worked
78       reliably by Wolfram Gloger, who contributed most of the
79       changes supporting this.
80
81  Assumed size_t  representation:       4 or 8 bytes
82       Note that size_t is allowed to be 4 bytes even if pointers are 8.       
83
84  Minimum overhead per allocated chunk: 4 or 8 bytes
85       Each malloced chunk has a hidden overhead of 4 bytes holding size
86       and status information. 
87
88  Minimum allocated size: 4-byte ptrs:  16 bytes    (including 4 overhead)
89                          8-byte ptrs:  24/32 bytes (including, 4/8 overhead)
90                                     
91       When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
92       ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
93       needed; 4 (8) for a trailing size field
94       and 8 (16) bytes for free list pointers. Thus, the minimum
95       allocatable size is 16/24/32 bytes.
96
97       Even a request for zero bytes (i.e., malloc(0)) returns a
98       pointer to something of the minimum allocatable size.
99
100  Maximum allocated size: 4-byte size_t: 2^31 -  8 bytes
101                          8-byte size_t: 2^63 - 16 bytes
102
103       It is assumed that (possibly signed) size_t bit values suffice to
104       represent chunk sizes. `Possibly signed' is due to the fact
105       that `size_t' may be defined on a system as either a signed or
106       an unsigned type. To be conservative, values that would appear
107       as negative numbers are avoided. 
108       Requests for sizes with a negative sign bit when the request
109       size is treaded as a long will return null.
110
111  Maximum overhead wastage per allocated chunk: normally 15 bytes
112
113       Alignnment demands, plus the minimum allocatable size restriction
114       make the normal worst-case wastage 15 bytes (i.e., up to 15
115       more bytes will be allocated than were requested in malloc), with
116       two exceptions:
117         1. Because requests for zero bytes allocate non-zero space,
118            the worst case wastage for a request of zero bytes is 24 bytes.
119         2. For requests >= mmap_threshold that are serviced via
120            mmap(), the worst case wastage is 8 bytes plus the remainder
121            from a system page (the minimal mmap unit); typically 4096 bytes.
122
123* Limitations
124
125    Here are some features that are NOT currently supported
126
127    * No user-definable hooks for callbacks and the like.
128    * No automated mechanism for fully checking that all accesses
129      to malloced memory stay within their bounds.
130    * No support for compaction.
131
132* Synopsis of compile-time options:
133
134    People have reported using previous versions of this malloc on all
135    versions of Unix, sometimes by tweaking some of the defines
136    below. It has been tested most extensively on Solaris and
137    Linux. It is also reported to work on WIN32 platforms.
138    People have also reported adapting this malloc for use in
139    stand-alone embedded systems.
140
141    The implementation is in straight, hand-tuned ANSI C.  Among other
142    consequences, it uses a lot of macros.  Because of this, to be at
143    all usable, this code should be compiled using an optimizing compiler
144    (for example gcc -O2) that can simplify expressions and control
145    paths.
146
147  __STD_C                  (default: derived from C compiler defines)
148     Nonzero if using ANSI-standard C compiler, a C++ compiler, or
149     a C compiler sufficiently close to ANSI to get away with it.
150  DEBUG                    (default: NOT defined)
151     Define to enable debugging. Adds fairly extensive assertion-based
152     checking to help track down memory errors, but noticeably slows down
153     execution.
154  REALLOC_ZERO_BYTES_FREES (default: NOT defined)
155     Define this if you think that realloc(p, 0) should be equivalent
156     to free(p). Otherwise, since malloc returns a unique pointer for
157     malloc(0), so does realloc(p, 0).
158  HAVE_MEMCPY               (default: defined)
159     Define if you are not otherwise using ANSI STD C, but still
160     have memcpy and memset in your C library and want to use them.
161     Otherwise, simple internal versions are supplied.
162  USE_MEMCPY               (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)
163     Define as 1 if you want the C library versions of memset and
164     memcpy called in realloc and calloc (otherwise macro versions are used).
165     At least on some platforms, the simple macro versions usually
166     outperform libc versions.
167  HAVE_MMAP                 (default: defined as 1)
168     Define to non-zero to optionally make malloc() use mmap() to
169     allocate very large blocks. 
170  HAVE_MREMAP                 (default: defined as 0 unless Linux libc set)
171     Define to non-zero to optionally make realloc() use mremap() to
172     reallocate very large blocks. 
173  malloc_getpagesize        (default: derived from system #includes)
174     Either a constant or routine call returning the system page size.
175  HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)
176     Optionally define if you are on a system with a /usr/include/malloc.h
177     that declares struct mallinfo. It is not at all necessary to
178     define this even if you do, but will ensure consistency.
179  INTERNAL_SIZE_T           (default: size_t)
180     Define to a 32-bit type (probably `unsigned int') if you are on a
181     64-bit machine, yet do not want or need to allow malloc requests of
182     greater than 2^31 to be handled. This saves space, especially for
183     very small chunks.
184  INTERNAL_LINUX_C_LIB      (default: NOT defined)
185     Defined only when compiled as part of Linux libc.
186     Also note that there is some odd internal name-mangling via defines
187     (for example, internally, `malloc' is named `mALLOc') needed
188     when compiling in this case. These look funny but don't otherwise
189     affect anything.
190  WIN32                     (default: undefined)
191     Define this on MS win (95, nt) platforms to compile in sbrk emulation.
192  LACKS_UNISTD_H            (default: undefined if not WIN32)
193     Define this if your system does not have a <unistd.h>.
194  LACKS_SYS_PARAM_H         (default: undefined if not WIN32)
195     Define this if your system does not have a <sys/param.h>.
196  MORECORE                  (default: sbrk)
197     The name of the routine to call to obtain more memory from the system.
198  MORECORE_FAILURE          (default: -1)
199     The value returned upon failure of MORECORE.
200  MORECORE_CLEARS           (default 1)
201     True (1) if the routine mapped to MORECORE zeroes out memory (which
202     holds for sbrk).
203  DEFAULT_TRIM_THRESHOLD
204  DEFAULT_TOP_PAD       
205  DEFAULT_MMAP_THRESHOLD
206  DEFAULT_MMAP_MAX     
207     Default values of tunable parameters (described in detail below)
208     controlling interaction with host system routines (sbrk, mmap, etc).
209     These values may also be changed dynamically via mallopt(). The
210     preset defaults are those that give best performance for typical
211     programs/systems.
212  USE_DL_PREFIX             (default: undefined)
213     Prefix all public routines with the string 'dl'.  Useful to
214     quickly avoid procedure declaration conflicts and linker symbol
215     conflicts with existing memory allocation routines.
216
217
218*/
219
220
221
222
223/* Preliminaries */
224
225#ifndef __STD_C
226#ifdef __STDC__
227#define __STD_C     1
228#else
229#if __cplusplus
230#define __STD_C     1
231#else
232#define __STD_C     0
233#endif /*__cplusplus*/
234#endif /*__STDC__*/
235#endif /*__STD_C*/
236
237#ifndef Void_t
238#if (__STD_C || defined(WIN32))
239#define Void_t      void
240#else
241#define Void_t      char
242#endif
243#endif /*Void_t*/
244
245#if __STD_C
246#include <stddef.h>   /* for size_t */
247#else
248#include <sys/types.h>
249#endif
250
251#ifdef __cplusplus
252extern "C" {
253#endif
254
255#include <stdio.h>    /* needed for malloc_stats */
256
257
258/*
259  Compile-time options
260*/
261
262
263/*
264    Debugging:
265
266    Because freed chunks may be overwritten with link fields, this
267    malloc will often die when freed memory is overwritten by user
268    programs.  This can be very effective (albeit in an annoying way)
269    in helping track down dangling pointers.
270
271    If you compile with -DDEBUG, a number of assertion checks are
272    enabled that will catch more memory errors. You probably won't be
273    able to make much sense of the actual assertion errors, but they
274    should help you locate incorrectly overwritten memory.  The
275    checking is fairly extensive, and will slow down execution
276    noticeably. Calling malloc_stats or mallinfo with DEBUG set will
277    attempt to check every non-mmapped allocated and free chunk in the
278    course of computing the summmaries. (By nature, mmapped regions
279    cannot be checked very much automatically.)
280
281    Setting DEBUG may also be helpful if you are trying to modify
282    this code. The assertions in the check routines spell out in more
283    detail the assumptions and invariants underlying the algorithms.
284
285*/
286
287#if DEBUG
288#include <assert.h>
289#else
290#define assert(x) ((void)0)
291#endif
292
293
294/*
295  INTERNAL_SIZE_T is the word-size used for internal bookkeeping
296  of chunk sizes. On a 64-bit machine, you can reduce malloc
297  overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'
298  at the expense of not being able to handle requests greater than
299  2^31. This limitation is hardly ever a concern; you are encouraged
300  to set this. However, the default version is the same as size_t.
301*/
302
303#ifndef INTERNAL_SIZE_T
304#define INTERNAL_SIZE_T size_t
305#endif
306
307/*
308  REALLOC_ZERO_BYTES_FREES should be set if a call to
309  realloc with zero bytes should be the same as a call to free.
310  Some people think it should. Otherwise, since this malloc
311  returns a unique pointer for malloc(0), so does realloc(p, 0).
312*/
313
314
315/*   #define REALLOC_ZERO_BYTES_FREES */
316
317
318/*
319  WIN32 causes an emulation of sbrk to be compiled in
320  mmap-based options are not currently supported in WIN32.
321*/
322
323/* #define WIN32 */
324#ifdef WIN32
325#define MORECORE wsbrk
326#define HAVE_MMAP 0
327
328#define LACKS_UNISTD_H
329#define LACKS_SYS_PARAM_H
330
331/*
332  Include 'windows.h' to get the necessary declarations for the
333  Microsoft Visual C++ data structures and routines used in the 'sbrk'
334  emulation.
335 
336  Define WIN32_LEAN_AND_MEAN so that only the essential Microsoft
337  Visual C++ header files are included.
338*/
339#define WIN32_LEAN_AND_MEAN
340#include <windows.h>
341#endif
342
343
344/*
345  HAVE_MEMCPY should be defined if you are not otherwise using
346  ANSI STD C, but still have memcpy and memset in your C library
347  and want to use them in calloc and realloc. Otherwise simple
348  macro versions are defined here.
349
350  USE_MEMCPY should be defined as 1 if you actually want to
351  have memset and memcpy called. People report that the macro
352  versions are often enough faster than libc versions on many
353  systems that it is better to use them.
354
355*/
356
357#define HAVE_MEMCPY
358
359#ifndef USE_MEMCPY
360#ifdef HAVE_MEMCPY
361#define USE_MEMCPY 1
362#else
363#define USE_MEMCPY 0
364#endif
365#endif
366
367#if (__STD_C || defined(HAVE_MEMCPY))
368
369#if __STD_C
370void* memset(void*, int, size_t);
371void* memcpy(void*, const void*, size_t);
372#else
373#ifdef WIN32
374// On Win32 platforms, 'memset()' and 'memcpy()' are already declared in
375// 'windows.h'
376#else
377Void_t* memset();
378Void_t* memcpy();
379#endif
380#endif
381#endif
382
383#if USE_MEMCPY
384
385/* The following macros are only invoked with (2n+1)-multiples of
386   INTERNAL_SIZE_T units, with a positive integer n. This is exploited
387   for fast inline execution when n is small. */
388
389#define MALLOC_ZERO(charp, nbytes)                                            \
390do {                                                                          \
391  INTERNAL_SIZE_T mzsz = (nbytes);                                            \
392  if(mzsz <= 9*sizeof(mzsz)) {                                                \
393    INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp);                         \
394    if(mzsz >= 5*sizeof(mzsz)) {     *mz++ = 0;                               \
395                                     *mz++ = 0;                               \
396      if(mzsz >= 7*sizeof(mzsz)) {   *mz++ = 0;                               \
397                                     *mz++ = 0;                               \
398        if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0;                               \
399                                     *mz++ = 0; }}}                           \
400                                     *mz++ = 0;                               \
401                                     *mz++ = 0;                               \
402                                     *mz   = 0;                               \
403  } else memset((charp), 0, mzsz);                                            \
404} while(0)
405
406#define MALLOC_COPY(dest,src,nbytes)                                          \
407do {                                                                          \
408  INTERNAL_SIZE_T mcsz = (nbytes);                                            \
409  if(mcsz <= 9*sizeof(mcsz)) {                                                \
410    INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src);                        \
411    INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest);                       \
412    if(mcsz >= 5*sizeof(mcsz)) {     *mcdst++ = *mcsrc++;                     \
413                                     *mcdst++ = *mcsrc++;                     \
414      if(mcsz >= 7*sizeof(mcsz)) {   *mcdst++ = *mcsrc++;                     \
415                                     *mcdst++ = *mcsrc++;                     \
416        if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++;                     \
417                                     *mcdst++ = *mcsrc++; }}}                 \
418                                     *mcdst++ = *mcsrc++;                     \
419                                     *mcdst++ = *mcsrc++;                     \
420                                     *mcdst   = *mcsrc  ;                     \
421  } else memcpy(dest, src, mcsz);                                             \
422} while(0)
423
424#else /* !USE_MEMCPY */
425
426/* Use Duff's device for good zeroing/copying performance. */
427
428#define MALLOC_ZERO(charp, nbytes)                                            \
429do {                                                                          \
430  INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp);                           \
431  long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn;                         \
432  if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; }             \
433  switch (mctmp) {                                                            \
434    case 0: for(;;) { *mzp++ = 0;                                             \
435    case 7:           *mzp++ = 0;                                             \
436    case 6:           *mzp++ = 0;                                             \
437    case 5:           *mzp++ = 0;                                             \
438    case 4:           *mzp++ = 0;                                             \
439    case 3:           *mzp++ = 0;                                             \
440    case 2:           *mzp++ = 0;                                             \
441    case 1:           *mzp++ = 0; if(mcn <= 0) break; mcn--; }                \
442  }                                                                           \
443} while(0)
444
445#define MALLOC_COPY(dest,src,nbytes)                                          \
446do {                                                                          \
447  INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src;                            \
448  INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest;                           \
449  long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn;                         \
450  if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; }             \
451  switch (mctmp) {                                                            \
452    case 0: for(;;) { *mcdst++ = *mcsrc++;                                    \
453    case 7:           *mcdst++ = *mcsrc++;                                    \
454    case 6:           *mcdst++ = *mcsrc++;                                    \
455    case 5:           *mcdst++ = *mcsrc++;                                    \
456    case 4:           *mcdst++ = *mcsrc++;                                    \
457    case 3:           *mcdst++ = *mcsrc++;                                    \
458    case 2:           *mcdst++ = *mcsrc++;                                    \
459    case 1:           *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; }       \
460  }                                                                           \
461} while(0)
462
463#endif
464
465
466/*
467  Define HAVE_MMAP to optionally make malloc() use mmap() to
468  allocate very large blocks.  These will be returned to the
469  operating system immediately after a free().
470*/
471
472#ifndef HAVE_MMAP
473#define HAVE_MMAP 1
474#endif
475
476/*
477  Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
478  large blocks.  This is currently only possible on Linux with
479  kernel versions newer than 1.3.77.
480*/
481
482#ifndef HAVE_MREMAP
483#ifdef INTERNAL_LINUX_C_LIB
484#define HAVE_MREMAP 1
485#else
486#define HAVE_MREMAP 0
487#endif
488#endif
489
490#if HAVE_MMAP
491
492#include <unistd.h>
493#include <fcntl.h>
494#include <sys/mman.h>
495
496#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
497#define MAP_ANONYMOUS MAP_ANON
498#endif
499
500#endif /* HAVE_MMAP */
501
502/*
503  Access to system page size. To the extent possible, this malloc
504  manages memory from the system in page-size units.
505 
506  The following mechanics for getpagesize were adapted from
507  bsd/gnu getpagesize.h
508*/
509
510#ifndef LACKS_UNISTD_H
511#  include <unistd.h>
512#endif
513
514#ifndef malloc_getpagesize
515#  ifdef _SC_PAGESIZE         /* some SVR4 systems omit an underscore */
516#    ifndef _SC_PAGE_SIZE
517#      define _SC_PAGE_SIZE _SC_PAGESIZE
518#    endif
519#  endif
520#  ifdef _SC_PAGE_SIZE
521#    define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
522#  else
523#    if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
524       extern size_t getpagesize();
525#      define malloc_getpagesize getpagesize()
526#    else
527#      ifdef WIN32
528#        define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */
529#      else
530#        ifndef LACKS_SYS_PARAM_H
531#          include <sys/param.h>
532#        endif
533#        ifdef EXEC_PAGESIZE
534#          define malloc_getpagesize EXEC_PAGESIZE
535#        else
536#          ifdef NBPG
537#            ifndef CLSIZE
538#              define malloc_getpagesize NBPG
539#            else
540#              define malloc_getpagesize (NBPG * CLSIZE)
541#            endif
542#          else
543#            ifdef NBPC
544#              define malloc_getpagesize NBPC
545#            else
546#              ifdef PAGESIZE
547#                define malloc_getpagesize PAGESIZE
548#              else
549#                define malloc_getpagesize (4096) /* just guess */
550#              endif
551#            endif
552#          endif
553#        endif
554#      endif
555#    endif
556#  endif
557#endif
558
559
560
561/*
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
624
625#ifndef DEFAULT_TRIM_THRESHOLD
626#define DEFAULT_TRIM_THRESHOLD (128 * 1024)
627#endif
628
629/*
630    M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
631      to keep before releasing via malloc_trim in free().
632
633      Automatic trimming is mainly useful in long-lived programs.
634      Because trimming via sbrk can be slow on some systems, and can
635      sometimes be wasteful (in cases where programs immediately
636      afterward allocate more large chunks) the value should be high
637      enough so that your overall system performance would improve by
638      releasing. 
639
640      The trim threshold and the mmap control parameters (see below)
641      can be traded off with one another. Trimming and mmapping are
642      two different ways of releasing unused memory back to the
643      system. Between these two, it is often possible to keep
644      system-level demands of a long-lived program down to a bare
645      minimum. For example, in one test suite of sessions measuring
646      the XF86 X server on Linux, using a trim threshold of 128K and a
647      mmap threshold of 192K led to near-minimal long term resource
648      consumption. 
649
650      If you are using this malloc in a long-lived program, it should
651      pay to experiment with these values.  As a rough guide, you
652      might set to a value close to the average size of a process
653      (program) running on your system.  Releasing this much memory
654      would allow such a process to run in memory.  Generally, it's
655      worth it to tune for trimming rather tham memory mapping when a
656      program undergoes phases where several large chunks are
657      allocated and released in ways that can reuse each other's
658      storage, perhaps mixed with phases where there are no such
659      chunks at all.  And in well-behaved long-lived programs,
660      controlling release of large blocks via trimming versus mapping
661      is usually faster.
662
663      However, in most programs, these parameters serve mainly as
664      protection against the system-level effects of carrying around
665      massive amounts of unneeded memory. Since frequent calls to
666      sbrk, mmap, and munmap otherwise degrade performance, the default
667      parameters are set to relatively high values that serve only as
668      safeguards.
669
670      The default trim value is high enough to cause trimming only in
671      fairly extreme (by current memory consumption standards) cases.
672      It must be greater than page size to have any useful effect.  To
673      disable trimming completely, you can set to (unsigned long)(-1);
674
675
676*/
677
678
679#ifndef DEFAULT_TOP_PAD
680#define DEFAULT_TOP_PAD        (0)
681#endif
682
683/*
684    M_TOP_PAD is the amount of extra `padding' space to allocate or
685      retain whenever sbrk is called. It is used in two ways internally:
686
687      * When sbrk is called to extend the top of the arena to satisfy
688        a new malloc request, this much padding is added to the sbrk
689        request.
690
691      * When malloc_trim is called automatically from free(),
692        it is used as the `pad' argument.
693
694      In both cases, the actual amount of padding is rounded
695      so that the end of the arena is always a system page boundary.
696
697      The main reason for using padding is to avoid calling sbrk so
698      often. Having even a small pad greatly reduces the likelihood
699      that nearly every malloc request during program start-up (or
700      after trimming) will invoke sbrk, which needlessly wastes
701      time.
702
703      Automatic rounding-up to page-size units is normally sufficient
704      to avoid measurable overhead, so the default is 0.  However, in
705      systems where sbrk is relatively slow, it can pay to increase
706      this value, at the expense of carrying around more memory than
707      the program needs.
708
709*/
710
711
712#ifndef DEFAULT_MMAP_THRESHOLD
713#define DEFAULT_MMAP_THRESHOLD (128 * 1024)
714#endif
715
716/*
717
718    M_MMAP_THRESHOLD is the request size threshold for using mmap()
719      to service a request. Requests of at least this size that cannot
720      be allocated using already-existing space will be serviced via mmap. 
721      (If enough normal freed space already exists it is used instead.)
722
723      Using mmap segregates relatively large chunks of memory so that
724      they can be individually obtained and released from the host
725      system. A request serviced through mmap is never reused by any
726      other request (at least not directly; the system may just so
727      happen to remap successive requests to the same locations).
728
729      Segregating space in this way has the benefit that mmapped space
730      can ALWAYS be individually released back to the system, which
731      helps keep the system level memory demands of a long-lived
732      program low. Mapped memory can never become `locked' between
733      other chunks, as can happen with normally allocated chunks, which
734      menas that even trimming via malloc_trim would not release them.
735
736      However, it has the disadvantages that:
737
738         1. The space cannot be reclaimed, consolidated, and then
739            used to service later requests, as happens with normal chunks.
740         2. It can lead to more wastage because of mmap page alignment
741            requirements
742         3. It causes malloc performance to be more dependent on host
743            system memory management support routines which may vary in
744            implementation quality and may impose arbitrary
745            limitations. Generally, servicing a request via normal
746            malloc steps is faster than going through a system's mmap.
747
748      All together, these considerations should lead you to use mmap
749      only for relatively large requests. 
750
751
752*/
753
754
755
756#ifndef DEFAULT_MMAP_MAX
757#if HAVE_MMAP
758#define DEFAULT_MMAP_MAX       (64)
759#else
760#define DEFAULT_MMAP_MAX       (0)
761#endif
762#endif
763
764/*
765    M_MMAP_MAX is the maximum number of requests to simultaneously
766      service using mmap. This parameter exists because:
767
768         1. Some systems have a limited number of internal tables for
769            use by mmap.
770         2. In most systems, overreliance on mmap can degrade overall
771            performance.
772         3. If a program allocates many large regions, it is probably
773            better off using normal sbrk-based allocation routines that
774            can reclaim and reallocate normal heap memory. Using a
775            small value allows transition into this mode after the
776            first few allocations.
777
778      Setting to 0 disables all use of mmap.  If HAVE_MMAP is not set,
779      the default value is 0, and attempts to set it to non-zero values
780      in mallopt will fail.
781*/
782
783
784
785
786/*
787    USE_DL_PREFIX will prefix all public routines with the string 'dl'.
788      Useful to quickly avoid procedure declaration conflicts and linker
789      symbol conflicts with existing memory allocation routines.
790
791*/
792
793/* #define USE_DL_PREFIX */
794
795
796
797
798/*
799
800  Special defines for linux libc
801
802  Except when compiled using these special defines for Linux libc
803  using weak aliases, this malloc is NOT designed to work in
804  multithreaded applications.  No semaphores or other concurrency
805  control are provided to ensure that multiple malloc or free calls
806  don't run at the same time, which could be disasterous. A single
807  semaphore could be used across malloc, realloc, and free (which is
808  essentially the effect of the linux weak alias approach). It would
809  be hard to obtain finer granularity.
810
811*/
812
813
814#ifdef INTERNAL_LINUX_C_LIB
815
816#if __STD_C
817
818Void_t * __default_morecore_init (ptrdiff_t);
819Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init;
820
821#else
822
823Void_t * __default_morecore_init ();
824Void_t *(*__morecore)() = __default_morecore_init;
825
826#endif
827
828#define MORECORE (*__morecore)
829#define MORECORE_FAILURE 0
830#define MORECORE_CLEARS 1
831
832#else /* INTERNAL_LINUX_C_LIB */
833
834#if __STD_C
835extern Void_t*     sbrk(ptrdiff_t);
836#else
837extern Void_t*     sbrk();
838#endif
839
840#ifndef MORECORE
841#define MORECORE sbrk
842#endif
843
844#ifndef MORECORE_FAILURE
845#define MORECORE_FAILURE -1
846#endif
847
848#ifndef MORECORE_CLEARS
849#define MORECORE_CLEARS 1
850#endif
851
852#endif /* INTERNAL_LINUX_C_LIB */
853
854#if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__)
855
856#define cALLOc          __libc_calloc
857#define fREe            __libc_free
858#define mALLOc          __libc_malloc
859#define mEMALIGn        __libc_memalign
860#define rEALLOc         __libc_realloc
861#define vALLOc          __libc_valloc
862#define pvALLOc         __libc_pvalloc
863#define mALLINFo        __libc_mallinfo
864#define mALLOPt         __libc_mallopt
865
866#pragma weak calloc = __libc_calloc
867#pragma weak free = __libc_free
868#pragma weak cfree = __libc_free
869#pragma weak malloc = __libc_malloc
870#pragma weak memalign = __libc_memalign
871#pragma weak realloc = __libc_realloc
872#pragma weak valloc = __libc_valloc
873#pragma weak pvalloc = __libc_pvalloc
874#pragma weak mallinfo = __libc_mallinfo
875#pragma weak mallopt = __libc_mallopt
876
877#else
878
879#ifdef USE_DL_PREFIX
880#define cALLOc          dlcalloc
881#define fREe            dlfree
882#define mALLOc          dlmalloc
883#define mEMALIGn        dlmemalign
884#define rEALLOc         dlrealloc
885#define vALLOc          dlvalloc
886#define pvALLOc         dlpvalloc
887#define mALLINFo        dlmallinfo
888#define mALLOPt         dlmallopt
889#else /* USE_DL_PREFIX */
890#define cALLOc          calloc
891#define fREe            free
892#define mALLOc          malloc
893#define mEMALIGn        memalign
894#define rEALLOc         realloc
895#define vALLOc          valloc
896#define pvALLOc         pvalloc
897#define mALLINFo        mallinfo
898#define mALLOPt         mallopt
899#endif /* USE_DL_PREFIX */
900
901#endif
902
903/* Public routines */
904
905#if __STD_C
906
907Void_t* mALLOc(size_t);
908void    fREe(Void_t*);
909Void_t* rEALLOc(Void_t*, size_t);
910Void_t* mEMALIGn(size_t, size_t);
911Void_t* vALLOc(size_t);
912Void_t* pvALLOc(size_t);
913Void_t* cALLOc(size_t, size_t);
914void    cfree(Void_t*);
915int     malloc_trim(size_t);
916size_t  malloc_usable_size(Void_t*);
917void    malloc_stats();
918int     mALLOPt(int, int);
919struct mallinfo mALLINFo(void);
920#else
921Void_t* mALLOc();
922void    fREe();
923Void_t* rEALLOc();
924Void_t* mEMALIGn();
925Void_t* vALLOc();
926Void_t* pvALLOc();
927Void_t* cALLOc();
928void    cfree();
929int     malloc_trim();
930size_t  malloc_usable_size();
931void    malloc_stats();
932int     mALLOPt();
933struct mallinfo mALLINFo();
934#endif
935
936
937#ifdef __cplusplus
938};  /* end of extern "C" */
939#endif
940
941/* ---------- To make a malloc.h, end cutting here ------------ */
942
943
944/*
945  Emulation of sbrk for WIN32
946  All code within the ifdef WIN32 is untested by me.
947
948  Thanks to Martin Fong and others for supplying this.
949*/
950
951
952#ifdef WIN32
953
954#define AlignPage(add) (((add) + (malloc_getpagesize-1)) & \
955~(malloc_getpagesize-1))
956#define AlignPage64K(add) (((add) + (0x10000 - 1)) & ~(0x10000 - 1))
957
958/* resrve 64MB to insure large contiguous space */ 
959#define RESERVED_SIZE (1024*1024*64)
960#define NEXT_SIZE (2048*1024)
961#define TOP_MEMORY ((unsigned long)2*1024*1024*1024)
962
963struct GmListElement;
964typedef struct GmListElement GmListElement;
965
966struct GmListElement
967{
968        GmListElement* next;
969        void* base;
970};
971
972static GmListElement* head = 0;
973static unsigned int gNextAddress = 0;
974static unsigned int gAddressBase = 0;
975static unsigned int gAllocatedSize = 0;
976
977static
978GmListElement* makeGmListElement (void* bas)
979{
980        GmListElement* this;
981        this = (GmListElement*)(void*)LocalAlloc (0, sizeof (GmListElement));
982        assert (this);
983        if (this)
984        {
985                this->base = bas;
986                this->next = head;
987                head = this;
988        }
989        return this;
990}
991
992void gcleanup ()
993{
994        BOOL rval;
995        assert ( (head == NULL) || (head->base == (void*)gAddressBase));
996        if (gAddressBase && (gNextAddress - gAddressBase))
997        {
998                rval = VirtualFree ((void*)gAddressBase, 
999                                                        gNextAddress - gAddressBase, 
1000                                                        MEM_DECOMMIT);
1001        assert (rval);
1002        }
1003        while (head)
1004        {
1005                GmListElement* next = head->next;
1006                rval = VirtualFree (head->base, 0, MEM_RELEASE);
1007                assert (rval);
1008                LocalFree (head);
1009                head = next;
1010        }
1011}
1012               
1013static
1014void* findRegion (void* start_address, unsigned long size)
1015{
1016        MEMORY_BASIC_INFORMATION info;
1017        if (size >= TOP_MEMORY) return NULL;
1018
1019        while ((unsigned long)start_address + size < TOP_MEMORY)
1020        {
1021                VirtualQuery (start_address, &info, sizeof (info));
1022                if ((info.State == MEM_FREE) && (info.RegionSize >= size))
1023                        return start_address;
1024                else
1025                {
1026                        // Requested region is not available so see if the
1027                        // next region is available.  Set 'start_address'
1028                        // to the next region and call 'VirtualQuery()'
1029                        // again.
1030
1031                        start_address = (char*)info.BaseAddress + info.RegionSize; 
1032
1033                        // Make sure we start looking for the next region
1034                        // on the *next* 64K boundary.  Otherwise, even if
1035                        // the new region is free according to
1036                        // 'VirtualQuery()', the subsequent call to
1037                        // 'VirtualAlloc()' (which follows the call to
1038                        // this routine in 'wsbrk()') will round *down*
1039                        // the requested address to a 64K boundary which
1040                        // we already know is an address in the
1041                        // unavailable region.  Thus, the subsequent call
1042                        // to 'VirtualAlloc()' will fail and bring us back
1043                        // here, causing us to go into an infinite loop.
1044
1045                        start_address =
1046                                (void *) AlignPage64K((unsigned long) start_address);
1047                }
1048        }
1049        return NULL;
1050       
1051}
1052
1053
1054void* wsbrk (long size)
1055{
1056        void* tmp;
1057        if (size > 0)
1058        {
1059                if (gAddressBase == 0)
1060                {
1061                        gAllocatedSize = max (RESERVED_SIZE, AlignPage (size));
1062                        gNextAddress = gAddressBase = 
1063                                (unsigned int)VirtualAlloc (NULL, gAllocatedSize, 
1064                                                                                        MEM_RESERVE, PAGE_NOACCESS);
1065                } else if (AlignPage (gNextAddress + size) > (gAddressBase +
1066gAllocatedSize))
1067                {
1068                        long new_size = max (NEXT_SIZE, AlignPage (size));
1069                        void* new_address = (void*)(gAddressBase+gAllocatedSize);
1070                        do 
1071                        {
1072                                new_address = findRegion (new_address, new_size);
1073                               
1074                                if (new_address == 0)
1075                                        return (void*)-1;
1076
1077                                gAddressBase = gNextAddress =
1078                                        (unsigned int)VirtualAlloc (new_address, new_size,
1079                                                                                                MEM_RESERVE, PAGE_NOACCESS);
1080                                // repeat in case of race condition
1081                                // The region that we found has been snagged
1082                                // by another thread
1083                        }
1084                        while (gAddressBase == 0);
1085
1086                        assert (new_address == (void*)gAddressBase);
1087
1088                        gAllocatedSize = new_size;
1089
1090                        if (!makeGmListElement ((void*)gAddressBase))
1091                                return (void*)-1;
1092                }
1093                if ((size + gNextAddress) > AlignPage (gNextAddress))
1094                {
1095                        void* res;
1096                        res = VirtualAlloc ((void*)AlignPage (gNextAddress),
1097                                                                (size + gNextAddress - 
1098                                                                 AlignPage (gNextAddress)), 
1099                                                                MEM_COMMIT, PAGE_READWRITE);
1100                        if (res == 0)
1101                                return (void*)-1;
1102                }
1103                tmp = (void*)gNextAddress;
1104                gNextAddress = (unsigned int)tmp + size;
1105                return tmp;
1106        }
1107        else if (size < 0)
1108        {
1109                unsigned int alignedGoal = AlignPage (gNextAddress + size);
1110                /* Trim by releasing the virtual memory */
1111                if (alignedGoal >= gAddressBase)
1112                {
1113                        VirtualFree ((void*)alignedGoal, gNextAddress - alignedGoal, 
1114                                                 MEM_DECOMMIT);
1115                        gNextAddress = gNextAddress + size;
1116                        return (void*)gNextAddress;
1117                }
1118                else 
1119                {
1120                        VirtualFree ((void*)gAddressBase, gNextAddress - gAddressBase,
1121                                                 MEM_DECOMMIT);
1122                        gNextAddress = gAddressBase;
1123                        return (void*)-1;
1124                }
1125        }
1126        else
1127        {
1128                return (void*)gNextAddress;
1129        }
1130}
1131
1132#endif
1133
1134
1135
1136/*
1137  Type declarations
1138*/
1139
1140
1141struct malloc_chunk
1142{
1143  INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */
1144  INTERNAL_SIZE_T size;      /* Size in bytes, including overhead. */
1145  struct malloc_chunk* fd;   /* double links -- used only if free. */
1146  struct malloc_chunk* bk;
1147};
1148
1149typedef struct malloc_chunk* mchunkptr;
1150
1151/*
1152
1153   malloc_chunk details:
1154
1155    (The following includes lightly edited explanations by Colin Plumb.)
1156
1157    Chunks of memory are maintained using a `boundary tag' method as
1158    described in e.g., Knuth or Standish.  (See the paper by Paul
1159    Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a
1160    survey of such techniques.)  Sizes of free chunks are stored both
1161    in the front of each chunk and at the end.  This makes
1162    consolidating fragmented chunks into bigger chunks very fast.  The
1163    size fields also hold bits representing whether chunks are free or
1164    in use.
1165
1166    An allocated chunk looks like this: 
1167
1168
1169    chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1170            |             Size of previous chunk, if allocated            | |
1171            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1172            |             Size of chunk, in bytes                         |P|
1173      mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1174            |             User data starts here...                          .
1175            .                                                               .
1176            .             (malloc_usable_space() bytes)                     .
1177            .                                                               |
1178nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1179            |             Size of chunk                                     |
1180            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1181
1182
1183    Where "chunk" is the front of the chunk for the purpose of most of
1184    the malloc code, but "mem" is the pointer that is returned to the
1185    user.  "Nextchunk" is the beginning of the next contiguous chunk.
1186
1187    Chunks always begin on even word boundries, so the mem portion
1188    (which is returned to the user) is also on an even word boundary, and
1189    thus double-word aligned.
1190
1191    Free chunks are stored in circular doubly-linked lists, and look like this:
1192
1193    chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1194            |             Size of previous chunk                            |
1195            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1196    `head:' |             Size of chunk, in bytes                         |P|
1197      mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1198            |             Forward pointer to next chunk in list             |
1199            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1200            |             Back pointer to previous chunk in list            |
1201            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1202            |             Unused space (may be 0 bytes long)                .
1203            .                                                               .
1204            .                                                               |
1205nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1206    `foot:' |             Size of chunk, in bytes                           |
1207            +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1208
1209    The P (PREV_INUSE) bit, stored in the unused low-order bit of the
1210    chunk size (which is always a multiple of two words), is an in-use
1211    bit for the *previous* chunk.  If that bit is *clear*, then the
1212    word before the current chunk size contains the previous chunk
1213    size, and can be used to find the front of the previous chunk.
1214    (The very first chunk allocated always has this bit set,
1215    preventing access to non-existent (or non-owned) memory.)
1216
1217    Note that the `foot' of the current chunk is actually represented
1218    as the prev_size of the NEXT chunk. (This makes it easier to
1219    deal with alignments etc).
1220
1221    The two exceptions to all this are
1222
1223     1. The special chunk `top', which doesn't bother using the
1224        trailing size field since there is no
1225        next contiguous chunk that would have to index off it. (After
1226        initialization, `top' is forced to always exist.  If it would
1227        become less than MINSIZE bytes long, it is replenished via
1228        malloc_extend_top.)
1229
1230     2. Chunks allocated via mmap, which have the second-lowest-order
1231        bit (IS_MMAPPED) set in their size fields.  Because they are
1232        never merged or traversed from any other chunk, they have no
1233        foot size or inuse information.
1234
1235    Available chunks are kept in any of several places (all declared below):
1236
1237    * `av': An array of chunks serving as bin headers for consolidated
1238       chunks. Each bin is doubly linked.  The bins are approximately
1239       proportionally (log) spaced.  There are a lot of these bins
1240       (128). This may look excessive, but works very well in
1241       practice.  All procedures maintain the invariant that no
1242       consolidated chunk physically borders another one. Chunks in
1243       bins are kept in size order, with ties going to the
1244       approximately least recently used chunk.
1245
1246       The chunks in each bin are maintained in decreasing sorted order by
1247       size.  This is irrelevant for the small bins, which all contain
1248       the same-sized chunks, but facilitates best-fit allocation for
1249       larger chunks. (These lists are just sequential. Keeping them in
1250       order almost never requires enough traversal to warrant using
1251       fancier ordered data structures.)  Chunks of the same size are
1252       linked with the most recently freed at the front, and allocations
1253       are taken from the back.  This results in LRU or FIFO allocation
1254       order, which tends to give each chunk an equal opportunity to be
1255       consolidated with adjacent freed chunks, resulting in larger free
1256       chunks and less fragmentation.
1257
1258    * `top': The top-most available chunk (i.e., the one bordering the
1259       end of available memory) is treated specially. It is never
1260       included in any bin, is used only if no other chunk is
1261       available, and is released back to the system if it is very
1262       large (see M_TRIM_THRESHOLD).
1263
1264    * `last_remainder': A bin holding only the remainder of the
1265       most recently split (non-top) chunk. This bin is checked
1266       before other non-fitting chunks, so as to provide better
1267       locality for runs of sequentially allocated chunks.
1268
1269    *  Implicitly, through the host system's memory mapping tables.
1270       If supported, requests greater than a threshold are usually
1271       serviced via calls to mmap, and then later released via munmap.
1272
1273*/
1274
1275
1276
1277
1278
1279
1280/*  sizes, alignments */
1281
1282#define SIZE_SZ                (sizeof(INTERNAL_SIZE_T))
1283#define MALLOC_ALIGNMENT       (SIZE_SZ + SIZE_SZ)
1284#define MALLOC_ALIGN_MASK      (MALLOC_ALIGNMENT - 1)
1285#define MINSIZE                (sizeof(struct malloc_chunk))
1286
1287/* conversion from malloc headers to user pointers, and back */
1288
1289#define chunk2mem(p)   ((Void_t*)((char*)(p) + 2*SIZE_SZ))
1290#define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ))
1291
1292/* pad request bytes into a usable size */
1293
1294#define request2size(req) \
1295 (((long)((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \
1296  (long)(MINSIZE + MALLOC_ALIGN_MASK)) ? MINSIZE : \
1297   (((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) & ~(MALLOC_ALIGN_MASK)))
1298
1299/* Check if m has acceptable alignment */
1300
1301#define aligned_OK(m)    (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0)
1302
1303
1304
1305
1306/*
1307  Physical chunk operations 
1308*/
1309
1310
1311/* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */
1312
1313#define PREV_INUSE 0x1
1314
1315/* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */
1316
1317#define IS_MMAPPED 0x2
1318
1319/* Bits to mask off when extracting size */
1320
1321#define SIZE_BITS (PREV_INUSE|IS_MMAPPED)
1322
1323
1324/* Ptr to next physical malloc_chunk. */
1325
1326#define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) ))
1327
1328/* Ptr to previous physical malloc_chunk */
1329
1330#define prev_chunk(p)\
1331   ((mchunkptr)( ((char*)(p)) - ((p)->prev_size) ))
1332
1333
1334/* Treat space at ptr + offset as a chunk */
1335
1336#define chunk_at_offset(p, s)  ((mchunkptr)(((char*)(p)) + (s)))
1337
1338
1339
1340
1341/*
1342  Dealing with use bits
1343*/
1344
1345/* extract p's inuse bit */
1346
1347#define inuse(p)\
1348((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE)
1349
1350/* extract inuse bit of previous chunk */
1351
1352#define prev_inuse(p)  ((p)->size & PREV_INUSE)
1353
1354/* check for mmap()'ed chunk */
1355
1356#define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED)
1357
1358/* set/clear chunk as in use without otherwise disturbing */
1359
1360#define set_inuse(p)\
1361((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE
1362
1363#define clear_inuse(p)\
1364((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE)
1365
1366/* check/set/clear inuse bits in known places */
1367
1368#define inuse_bit_at_offset(p, s)\
1369 (((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE)
1370
1371#define set_inuse_bit_at_offset(p, s)\
1372 (((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE)
1373
1374#define clear_inuse_bit_at_offset(p, s)\
1375 (((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE))
1376
1377
1378
1379
1380/*
1381  Dealing with size fields
1382*/
1383
1384/* Get size, ignoring use bits */
1385
1386#define chunksize(p)          ((p)->size & ~(SIZE_BITS))
1387
1388/* Set size at head, without disturbing its use bit */
1389
1390#define set_head_size(p, s)   ((p)->size = (((p)->size & PREV_INUSE) | (s)))
1391
1392/* Set size/use ignoring previous bits in header */
1393
1394#define set_head(p, s)        ((p)->size = (s))
1395
1396/* Set size at footer (only when chunk is not in use) */
1397
1398#define set_foot(p, s)   (((mchunkptr)((char*)(p) + (s)))->prev_size = (s))
1399
1400
1401
1402
1403
1404/*
1405   Bins
1406
1407    The bins, `av_' are an array of pairs of pointers serving as the
1408    heads of (initially empty) doubly-linked lists of chunks, laid out
1409    in a way so that each pair can be treated as if it were in a
1410    malloc_chunk. (This way, the fd/bk offsets for linking bin heads
1411    and chunks are the same).
1412
1413    Bins for sizes < 512 bytes contain chunks of all the same size, spaced
1414    8 bytes apart. Larger bins are approximately logarithmically
1415    spaced. (See the table below.) The `av_' array is never mentioned
1416    directly in the code, but instead via bin access macros.
1417
1418    Bin layout:
1419
1420    64 bins of size       8
1421    32 bins of size      64
1422    16 bins of size     512
1423     8 bins of size    4096
1424     4 bins of size   32768
1425     2 bins of size  262144
1426     1 bin  of size what's left
1427
1428    There is actually a little bit of slop in the numbers in bin_index
1429    for the sake of speed. This makes no difference elsewhere.
1430
1431    The special chunks `top' and `last_remainder' get their own bins,
1432    (this is implemented via yet more trickery with the av_ array),
1433    although `top' is never properly linked to its bin since it is
1434    always handled specially.
1435
1436*/
1437
1438#define NAV             128   /* number of bins */
1439
1440typedef struct malloc_chunk* mbinptr;
1441
1442/* access macros */
1443
1444#define bin_at(i)      ((mbinptr)((char*)&(av_[2*(i) + 2]) - 2*SIZE_SZ))
1445#define next_bin(b)    ((mbinptr)((char*)(b) + 2 * sizeof(mbinptr)))
1446#define prev_bin(b)    ((mbinptr)((char*)(b) - 2 * sizeof(mbinptr)))
1447
1448/*
1449   The first 2 bins are never indexed. The corresponding av_ cells are instead
1450   used for bookkeeping. This is not to save space, but to simplify
1451   indexing, maintain locality, and avoid some initialization tests.
1452*/
1453
1454#define top            (bin_at(0)->fd)   /* The topmost chunk */
1455#define last_remainder (bin_at(1))       /* remainder from last split */
1456
1457
1458/*
1459   Because top initially points to its own bin with initial
1460   zero size, thus forcing extension on the first malloc request,
1461   we avoid having any special code in malloc to check whether
1462   it even exists yet. But we still need to in malloc_extend_top.
1463*/
1464
1465#define initial_top    ((mchunkptr)(bin_at(0)))
1466
1467/* Helper macro to initialize bins */
1468
1469#define IAV(i)  bin_at(i), bin_at(i)
1470
1471static mbinptr av_[NAV * 2 + 2] = {
1472 0, 0,
1473 IAV(0),   IAV(1),   IAV(2),   IAV(3),   IAV(4),   IAV(5),   IAV(6),   IAV(7),
1474 IAV(8),   IAV(9),   IAV(10),  IAV(11),  IAV(12),  IAV(13),  IAV(14),  IAV(15),
1475 IAV(16),  IAV(17),  IAV(18),  IAV(19),  IAV(20),  IAV(21),  IAV(22),  IAV(23),
1476 IAV(24),  IAV(25),  IAV(26),  IAV(27),  IAV(28),  IAV(29),  IAV(30),  IAV(31),
1477 IAV(32),  IAV(33),  IAV(34),  IAV(35),  IAV(36),  IAV(37),  IAV(38),  IAV(39),
1478 IAV(40),  IAV(41),  IAV(42),  IAV(43),  IAV(44),  IAV(45),  IAV(46),  IAV(47),
1479 IAV(48),  IAV(49),  IAV(50),  IAV(51),  IAV(52),  IAV(53),  IAV(54),  IAV(55),
1480 IAV(56),  IAV(57),  IAV(58),  IAV(59),  IAV(60),  IAV(61),  IAV(62),  IAV(63),
1481 IAV(64),  IAV(65),  IAV(66),  IAV(67),  IAV(68),  IAV(69),  IAV(70),  IAV(71),
1482 IAV(72),  IAV(73),  IAV(74),  IAV(75),  IAV(76),  IAV(77),  IAV(78),  IAV(79),
1483 IAV(80),  IAV(81),  IAV(82),  IAV(83),  IAV(84),  IAV(85),  IAV(86),  IAV(87),
1484 IAV(88),  IAV(89),  IAV(90),  IAV(91),  IAV(92),  IAV(93),  IAV(94),  IAV(95),
1485 IAV(96),  IAV(97),  IAV(98),  IAV(99),  IAV(100), IAV(101), IAV(102), IAV(103),
1486 IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111),
1487 IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119),
1488 IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127)
1489};
1490
1491
1492
1493/* field-extraction macros */
1494
1495#define first(b) ((b)->fd)
1496#define last(b)  ((b)->bk)
1497
1498/*
1499  Indexing into bins
1500*/
1501
1502#define bin_index(sz)                                                          \
1503(((((unsigned long)(sz)) >> 9) ==    0) ?       (((unsigned long)(sz)) >>  3): \
1504 ((((unsigned long)(sz)) >> 9) <=    4) ?  56 + (((unsigned long)(sz)) >>  6): \
1505 ((((unsigned long)(sz)) >> 9) <=   20) ?  91 + (((unsigned long)(sz)) >>  9): \
1506 ((((unsigned long)(sz)) >> 9) <=   84) ? 110 + (((unsigned long)(sz)) >> 12): \
1507 ((((unsigned long)(sz)) >> 9) <=  340) ? 119 + (((unsigned long)(sz)) >> 15): \
1508 ((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18): \
1509                                          126)                     
1510/*
1511  bins for chunks < 512 are all spaced 8 bytes apart, and hold
1512  identically sized chunks. This is exploited in malloc.
1513*/
1514
1515#define MAX_SMALLBIN         63
1516#define MAX_SMALLBIN_SIZE   512
1517#define SMALLBIN_WIDTH        8
1518
1519#define smallbin_index(sz)  (((unsigned long)(sz)) >> 3)
1520
1521/*
1522   Requests are `small' if both the corresponding and the next bin are small
1523*/
1524
1525#define is_small_request(nb) (nb < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH)
1526
1527
1528
1529/*
1530    To help compensate for the large number of bins, a one-level index
1531    structure is used for bin-by-bin searching.  `binblocks' is a
1532    one-word bitvector recording whether groups of BINBLOCKWIDTH bins
1533    have any (possibly) non-empty bins, so they can be skipped over
1534    all at once during during traversals. The bits are NOT always
1535    cleared as soon as all bins in a block are empty, but instead only
1536    when all are noticed to be empty during traversal in malloc.
1537*/
1538
1539#define BINBLOCKWIDTH     4   /* bins per block */
1540
1541#define binblocks      (bin_at(0)->size) /* bitvector of nonempty blocks */
1542
1543/* bin<->block macros */
1544
1545#define idx2binblock(ix)    ((unsigned)1 << (ix / BINBLOCKWIDTH))
1546#define mark_binblock(ii)   (binblocks |= idx2binblock(ii))
1547#define clear_binblock(ii)  (binblocks &= ~(idx2binblock(ii)))
1548
1549
1550
1551
1552
1553/*  Other static bookkeeping data */
1554
1555/* variables holding tunable values */
1556
1557static unsigned long trim_threshold   = DEFAULT_TRIM_THRESHOLD;
1558static unsigned long top_pad          = DEFAULT_TOP_PAD;
1559static unsigned int  n_mmaps_max      = DEFAULT_MMAP_MAX;
1560static unsigned long mmap_threshold   = DEFAULT_MMAP_THRESHOLD;
1561
1562/* The first value returned from sbrk */
1563static char* sbrk_base = (char*)(-1);
1564
1565/* The maximum memory obtained from system via sbrk */
1566static unsigned long max_sbrked_mem = 0; 
1567
1568/* The maximum via either sbrk or mmap */
1569static unsigned long max_total_mem = 0; 
1570
1571/* internal working copy of mallinfo */
1572static struct mallinfo current_mallinfo = {  0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
1573
1574/* The total memory obtained from system via sbrk */
1575#define sbrked_mem  (current_mallinfo.arena)
1576
1577/* Tracking mmaps */
1578
1579static unsigned int n_mmaps = 0;
1580static unsigned int max_n_mmaps = 0;
1581static unsigned long mmapped_mem = 0;
1582static unsigned long max_mmapped_mem = 0;
1583
1584
1585
1586/*
1587  Debugging support
1588*/
1589
1590#if DEBUG
1591
1592
1593/*
1594  These routines make a number of assertions about the states
1595  of data structures that should be true at all times. If any
1596  are not true, it's very likely that a user program has somehow
1597  trashed memory. (It's also possible that there is a coding error
1598  in malloc. In which case, please report it!)
1599*/
1600
1601#if __STD_C
1602static void do_check_chunk(mchunkptr p) 
1603#else
1604static void do_check_chunk(p) mchunkptr p;
1605#endif
1606{ 
1607  INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
1608
1609  /* No checkable chunk is mmapped */
1610  assert(!chunk_is_mmapped(p));
1611
1612  /* Check for legal address ... */
1613  assert((char*)p >= sbrk_base);
1614  if (p != top) 
1615    assert((char*)p + sz <= (char*)top);
1616  else
1617    assert((char*)p + sz <= sbrk_base + sbrked_mem);
1618
1619}
1620
1621
1622#if __STD_C
1623static void do_check_free_chunk(mchunkptr p) 
1624#else
1625static void do_check_free_chunk(p) mchunkptr p;
1626#endif
1627{ 
1628  INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
1629  mchunkptr next = chunk_at_offset(p, sz);
1630
1631  do_check_chunk(p);
1632
1633  /* Check whether it claims to be free ... */
1634  assert(!inuse(p));
1635
1636  /* Unless a special marker, must have OK fields */
1637  if ((long)sz >= (long)MINSIZE)
1638  {
1639    assert((sz & MALLOC_ALIGN_MASK) == 0);
1640    assert(aligned_OK(chunk2mem(p)));
1641    /* ... matching footer field */
1642    assert(next->prev_size == sz);
1643    /* ... and is fully consolidated */
1644    assert(prev_inuse(p));
1645    assert (next == top || inuse(next));
1646   
1647    /* ... and has minimally sane links */
1648    assert(p->fd->bk == p);
1649    assert(p->bk->fd == p);
1650  }
1651  else /* markers are always of size SIZE_SZ */
1652    assert(sz == SIZE_SZ); 
1653}
1654
1655#if __STD_C
1656static void do_check_inuse_chunk(mchunkptr p) 
1657#else
1658static void do_check_inuse_chunk(p) mchunkptr p;
1659#endif
1660{ 
1661  mchunkptr next = next_chunk(p);
1662  do_check_chunk(p);
1663
1664  /* Check whether it claims to be in use ... */
1665  assert(inuse(p));
1666
1667  /* ... and is surrounded by OK chunks.
1668    Since more things can be checked with free chunks than inuse ones,
1669    if an inuse chunk borders them and debug is on, it's worth doing them.
1670  */
1671  if (!prev_inuse(p)) 
1672  {
1673    mchunkptr prv = prev_chunk(p);
1674    assert(next_chunk(prv) == p);
1675    do_check_free_chunk(prv);
1676  }
1677  if (next == top)
1678  {
1679    assert(prev_inuse(next));
1680    assert(chunksize(next) >= MINSIZE);
1681  }
1682  else if (!inuse(next))
1683    do_check_free_chunk(next);
1684
1685}
1686
1687#if __STD_C
1688static void do_check_malloced_chunk(mchunkptr p, INTERNAL_SIZE_T s) 
1689#else
1690static void do_check_malloced_chunk(p, s) mchunkptr p; INTERNAL_SIZE_T s;
1691#endif
1692{
1693  INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE;
1694  long room = sz - s;
1695
1696  do_check_inuse_chunk(p);
1697
1698  /* Legal size ... */
1699  assert((long)sz >= (long)MINSIZE);
1700  assert((sz & MALLOC_ALIGN_MASK) == 0);
1701  assert(room >= 0);
1702  assert(room < (long)MINSIZE);
1703
1704  /* ... and alignment */
1705  assert(aligned_OK(chunk2mem(p)));
1706
1707
1708  /* ... and was allocated at front of an available chunk */
1709  assert(prev_inuse(p));
1710
1711}
1712
1713
1714#define check_free_chunk(P)  do_check_free_chunk(P)
1715#define check_inuse_chunk(P) do_check_inuse_chunk(P)
1716#define check_chunk(P) do_check_chunk(P)
1717#define check_malloced_chunk(P,N) do_check_malloced_chunk(P,N)
1718#else
1719#define check_free_chunk(P)
1720#define check_inuse_chunk(P)
1721#define check_chunk(P)
1722#define check_malloced_chunk(P,N)
1723#endif
1724
1725
1726
1727/*
1728  Macro-based internal utilities
1729*/
1730
1731
1732/* 
1733  Linking chunks in bin lists.
1734  Call these only with variables, not arbitrary expressions, as arguments.
1735*/
1736
1737/*
1738  Place chunk p of size s in its bin, in size order,
1739  putting it ahead of others of same size.
1740*/
1741
1742
1743#define frontlink(P, S, IDX, BK, FD)                                          \
1744{                                                                             \
1745  if (S < MAX_SMALLBIN_SIZE)                                                  \
1746  {                                                                           \
1747    IDX = smallbin_index(S);                                                  \
1748    mark_binblock(IDX);                                                       \
1749    BK = bin_at(IDX);                                                         \
1750    FD = BK->fd;                                                              \
1751    P->bk = BK;                                                               \
1752    P->fd = FD;                                                               \
1753    FD->bk = BK->fd = P;                                                      \
1754  }                                                                           \
1755  else                                                                        \
1756  {                                                                           \
1757    IDX = bin_index(S);                                                       \
1758    BK = bin_at(IDX);                                                         \
1759    FD = BK->fd;                                                              \
1760    if (FD == BK) mark_binblock(IDX);                                         \
1761    else                                                                      \
1762    {                                                                         \
1763      while (FD != BK && S < chunksize(FD)) FD = FD->fd;                      \
1764      BK = FD->bk;                                                            \
1765    }                                                                         \
1766    P->bk = BK;                                                               \
1767    P->fd = FD;                                                               \
1768    FD->bk = BK->fd = P;                                                      \
1769  }                                                                           \
1770}
1771
1772
1773/* take a chunk off a list */
1774
1775#define unlink(P, BK, FD)                                                     \
1776{                                                                             \
1777  BK = P->bk;                                                                 \
1778  FD = P->fd;                                                                 \
1779  FD->bk = BK;                                                                \
1780  BK->fd = FD;                                                                \
1781}                                                                             \
1782
1783/* Place p as the last remainder */
1784
1785#define link_last_remainder(P)                                                \
1786{                                                                             \
1787  last_remainder->fd = last_remainder->bk =  P;                               \
1788  P->fd = P->bk = last_remainder;                                             \
1789}
1790
1791/* Clear the last_remainder bin */
1792
1793#define clear_last_remainder \
1794  (last_remainder->fd = last_remainder->bk = last_remainder)
1795
1796
1797
1798
1799
1800
1801/* Routines dealing with mmap(). */
1802
1803#if HAVE_MMAP
1804
1805#if __STD_C
1806static mchunkptr mmap_chunk(size_t size)
1807#else
1808static mchunkptr mmap_chunk(size) size_t size;
1809#endif
1810{
1811  size_t page_mask = malloc_getpagesize - 1;
1812  mchunkptr p;
1813
1814#ifndef MAP_ANONYMOUS
1815  static int fd = -1;
1816#endif
1817
1818  if(n_mmaps >= n_mmaps_max) return 0; /* too many regions */
1819
1820  /* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because
1821   * there is no following chunk whose prev_size field could be used.
1822   */
1823  size = (size + SIZE_SZ + page_mask) & ~page_mask;
1824
1825#ifdef MAP_ANONYMOUS
1826  p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE,
1827                      MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
1828#else /* !MAP_ANONYMOUS */
1829  if (fd < 0) 
1830  {
1831    fd = open("/dev/zero", O_RDWR);
1832    if(fd < 0) return 0;
1833  }
1834  p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
1835#endif
1836
1837  if(p == (mchunkptr)-1) return 0;
1838
1839  n_mmaps++;
1840  if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps;
1841 
1842  /* We demand that eight bytes into a page must be 8-byte aligned. */
1843  assert(aligned_OK(chunk2mem(p)));
1844
1845  /* The offset to the start of the mmapped region is stored
1846   * in the prev_size field of the chunk; normally it is zero,
1847   * but that can be changed in memalign().
1848   */
1849  p->prev_size = 0;
1850  set_head(p, size|IS_MMAPPED);
1851 
1852  mmapped_mem += size;
1853  if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem) 
1854    max_mmapped_mem = mmapped_mem;
1855  if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) 
1856    max_total_mem = mmapped_mem + sbrked_mem;
1857  return p;
1858}
1859
1860#if __STD_C
1861static void munmap_chunk(mchunkptr p)
1862#else
1863static void munmap_chunk(p) mchunkptr p;
1864#endif
1865{
1866  INTERNAL_SIZE_T size = chunksize(p);
1867  int ret;
1868
1869  assert (chunk_is_mmapped(p));
1870  assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
1871  assert((n_mmaps > 0));
1872  assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0);
1873
1874  n_mmaps--;
1875  mmapped_mem -= (size + p->prev_size);
1876
1877  ret = munmap((char *)p - p->prev_size, size + p->prev_size);
1878
1879  /* munmap returns non-zero on failure */
1880  assert(ret == 0);
1881}
1882
1883#if HAVE_MREMAP
1884
1885#if __STD_C
1886static mchunkptr mremap_chunk(mchunkptr p, size_t new_size)
1887#else
1888static mchunkptr mremap_chunk(p, new_size) mchunkptr p; size_t new_size;
1889#endif
1890{
1891  size_t page_mask = malloc_getpagesize - 1;
1892  INTERNAL_SIZE_T offset = p->prev_size;
1893  INTERNAL_SIZE_T size = chunksize(p);
1894  char *cp;
1895
1896  assert (chunk_is_mmapped(p));
1897  assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem));
1898  assert((n_mmaps > 0));
1899  assert(((size + offset) & (malloc_getpagesize-1)) == 0);
1900
1901  /* Note the extra SIZE_SZ overhead as in mmap_chunk(). */
1902  new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask;
1903
1904  cp = (char *)mremap((char *)p - offset, size + offset, new_size, 1);
1905
1906  if (cp == (char *)-1) return 0;
1907
1908  p = (mchunkptr)(cp + offset);
1909
1910  assert(aligned_OK(chunk2mem(p)));
1911
1912  assert((p->prev_size == offset));
1913  set_head(p, (new_size - offset)|IS_MMAPPED);
1914
1915  mmapped_mem -= size + offset;
1916  mmapped_mem += new_size;
1917  if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem) 
1918    max_mmapped_mem = mmapped_mem;
1919  if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem)
1920    max_total_mem = mmapped_mem + sbrked_mem;
1921  return p;
1922}
1923
1924#endif /* HAVE_MREMAP */
1925
1926#endif /* HAVE_MMAP */
1927
1928
1929
1930
1931/*
1932  Extend the top-most chunk by obtaining memory from system.
1933  Main interface to sbrk (but see also malloc_trim).
1934*/
1935
1936#if __STD_C
1937static void malloc_extend_top(INTERNAL_SIZE_T nb)
1938#else
1939static void malloc_extend_top(nb) INTERNAL_SIZE_T nb;
1940#endif
1941{
1942  char*     brk;                  /* return value from sbrk */
1943  INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */
1944  INTERNAL_SIZE_T correction;     /* bytes for 2nd sbrk call */
1945  char*     new_brk;              /* return of 2nd sbrk call */
1946  INTERNAL_SIZE_T top_size;       /* new size of top chunk */
1947
1948  mchunkptr old_top     = top;  /* Record state of old top */
1949  INTERNAL_SIZE_T old_top_size = chunksize(old_top);
1950  char*     old_end      = (char*)(chunk_at_offset(old_top, old_top_size));
1951
1952  /* Pad request with top_pad plus minimal overhead */
1953 
1954  INTERNAL_SIZE_T    sbrk_size     = nb + top_pad + MINSIZE;
1955  unsigned long pagesz    = malloc_getpagesize;
1956
1957  /* If not the first time through, round to preserve page boundary */
1958  /* Otherwise, we need to correct to a page size below anyway. */
1959  /* (We also correct below if an intervening foreign sbrk call.) */
1960
1961  if (sbrk_base != (char*)(-1))
1962    sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1);
1963
1964  brk = (char*)(MORECORE (sbrk_size));
1965
1966  /* Fail if sbrk failed or if a foreign sbrk call killed our space */
1967  if (brk == (char*)(MORECORE_FAILURE) || 
1968      (brk < old_end && old_top != initial_top))
1969    return;     
1970
1971  sbrked_mem += sbrk_size;
1972
1973  if (brk == old_end) /* can just add bytes to current top */
1974  {
1975    top_size = sbrk_size + old_top_size;
1976    set_head(top, top_size | PREV_INUSE);
1977  }
1978  else
1979  {
1980    if (sbrk_base == (char*)(-1))  /* First time through. Record base */
1981      sbrk_base = brk;
1982    else  /* Someone else called sbrk().  Count those bytes as sbrked_mem. */
1983      sbrked_mem += brk - (char*)old_end;
1984
1985    /* Guarantee alignment of first new chunk made from this space */
1986    front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK;
1987    if (front_misalign > 0) 
1988    {
1989      correction = (MALLOC_ALIGNMENT) - front_misalign;
1990      brk += correction;
1991    }
1992    else
1993      correction = 0;
1994
1995    /* Guarantee the next brk will be at a page boundary */
1996
1997    correction += ((((unsigned long)(brk + sbrk_size))+(pagesz-1)) &
1998                   ~(pagesz - 1)) - ((unsigned long)(brk + sbrk_size));
1999
2000    /* Allocate correction */
2001    new_brk = (char*)(MORECORE (correction));
2002    if (new_brk == (char*)(MORECORE_FAILURE)) return; 
2003
2004    sbrked_mem += correction;
2005
2006    top = (mchunkptr)brk;
2007    top_size = new_brk - brk + correction;
2008    set_head(top, top_size | PREV_INUSE);
2009
2010    if (old_top != initial_top)
2011    {
2012
2013      /* There must have been an intervening foreign sbrk call. */
2014      /* A double fencepost is necessary to prevent consolidation */
2015
2016      /* If not enough space to do this, then user did something very wrong */
2017      if (old_top_size < MINSIZE) 
2018      {
2019        set_head(top, PREV_INUSE); /* will force null return from malloc */
2020        return;
2021      }
2022
2023      /* Also keep size a multiple of MALLOC_ALIGNMENT */
2024      old_top_size = (old_top_size - 3*SIZE_SZ) & ~MALLOC_ALIGN_MASK;
2025      set_head_size(old_top, old_top_size);
2026      chunk_at_offset(old_top, old_top_size          )->size =
2027        SIZE_SZ|PREV_INUSE;
2028      chunk_at_offset(old_top, old_top_size + SIZE_SZ)->size =
2029        SIZE_SZ|PREV_INUSE;
2030      /* If possible, release the rest. */
2031      if (old_top_size >= MINSIZE) 
2032        fREe(chunk2mem(old_top));
2033    }
2034  }
2035
2036  if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem) 
2037    max_sbrked_mem = sbrked_mem;
2038  if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) 
2039    max_total_mem = mmapped_mem + sbrked_mem;
2040
2041  /* We always land on a page boundary */
2042  assert(((unsigned long)((char*)top + top_size) & (pagesz - 1)) == 0);
2043}
2044
2045
2046
2047
2048/* Main public routines */
2049
2050
2051/*
2052  Malloc Algorthim:
2053
2054    The requested size is first converted into a usable form, `nb'.
2055    This currently means to add 4 bytes overhead plus possibly more to
2056    obtain 8-byte alignment and/or to obtain a size of at least
2057    MINSIZE (currently 16 bytes), the smallest allocatable size.
2058    (All fits are considered `exact' if they are within MINSIZE bytes.)
2059
2060    From there, the first successful of the following steps is taken:
2061
2062      1. The bin corresponding to the request size is scanned, and if
2063         a chunk of exactly the right size is found, it is taken.
2064
2065      2. The most recently remaindered chunk is used if it is big
2066         enough.  This is a form of (roving) first fit, used only in
2067         the absence of exact fits. Runs of consecutive requests use
2068         the remainder of the chunk used for the previous such request
2069         whenever possible. This limited use of a first-fit style
2070         allocation strategy tends to give contiguous chunks
2071         coextensive lifetimes, which improves locality and can reduce
2072         fragmentation in the long run.
2073
2074      3. Other bins are scanned in increasing size order, using a
2075         chunk big enough to fulfill the request, and splitting off
2076         any remainder.  This search is strictly by best-fit; i.e.,
2077         the smallest (with ties going to approximately the least
2078         recently used) chunk that fits is selected.
2079
2080      4. If large enough, the chunk bordering the end of memory
2081         (`top') is split off. (This use of `top' is in accord with
2082         the best-fit search rule.  In effect, `top' is treated as
2083         larger (and thus less well fitting) than any other available
2084         chunk since it can be extended to be as large as necessary
2085         (up to system limitations).
2086
2087      5. If the request size meets the mmap threshold and the
2088         system supports mmap, and there are few enough currently
2089         allocated mmapped regions, and a call to mmap succeeds,
2090         the request is allocated via direct memory mapping.
2091
2092      6. Otherwise, the top of memory is extended by
2093         obtaining more space from the system (normally using sbrk,
2094         but definable to anything else via the MORECORE macro).
2095         Memory is gathered from the system (in system page-sized
2096         units) in a way that allows chunks obtained across different
2097         sbrk calls to be consolidated, but does not require
2098         contiguous memory. Thus, it should be safe to intersperse
2099         mallocs with other sbrk calls.
2100
2101
2102      All allocations are made from the the `lowest' part of any found
2103      chunk. (The implementation invariant is that prev_inuse is
2104      always true of any allocated chunk; i.e., that each allocated
2105      chunk borders either a previously allocated and still in-use chunk,
2106      or the base of its memory arena.)
2107
2108*/
2109
2110#if __STD_C
2111Void_t* mALLOc(size_t bytes)
2112#else
2113Void_t* mALLOc(bytes) size_t bytes;
2114#endif
2115{
2116  mchunkptr victim;                  /* inspected/selected chunk */
2117  INTERNAL_SIZE_T victim_size;       /* its size */
2118  int       idx;                     /* index for bin traversal */
2119  mbinptr   bin;                     /* associated bin */
2120  mchunkptr remainder;               /* remainder from a split */
2121  long      remainder_size;          /* its size */
2122  int       remainder_index;         /* its bin index */
2123  unsigned long block;               /* block traverser bit */
2124  int       startidx;                /* first bin of a traversed block */
2125  mchunkptr fwd;                     /* misc temp for linking */
2126  mchunkptr bck;                     /* misc temp for linking */
2127  mbinptr q;                         /* misc temp */
2128
2129  INTERNAL_SIZE_T nb;
2130
2131  if ((long)bytes < 0) return 0;
2132
2133  nb = request2size(bytes);  /* padded request size; */
2134
2135  /* Check for exact match in a bin */
2136
2137  if (is_small_request(nb))  /* Faster version for small requests */
2138  {
2139    idx = smallbin_index(nb); 
2140
2141    /* No traversal or size check necessary for small bins.  */
2142
2143    q = bin_at(idx);
2144    victim = last(q);
2145
2146    /* Also scan the next one, since it would have a remainder < MINSIZE */
2147    if (victim == q)
2148    {
2149      q = next_bin(q);
2150      victim = last(q);
2151    }
2152    if (victim != q)
2153    {
2154      victim_size = chunksize(victim);
2155      unlink(victim, bck, fwd);
2156      set_inuse_bit_at_offset(victim, victim_size);
2157      check_malloced_chunk(victim, nb);
2158      return chunk2mem(victim);
2159    }
2160
2161    idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */
2162
2163  }
2164  else
2165  {
2166    idx = bin_index(nb);
2167    bin = bin_at(idx);
2168
2169    for (victim = last(bin); victim != bin; victim = victim->bk)
2170    {
2171      victim_size = chunksize(victim);
2172      remainder_size = victim_size - nb;
2173     
2174      if (remainder_size >= (long)MINSIZE) /* too big */
2175      {
2176        --idx; /* adjust to rescan below after checking last remainder */
2177        break;   
2178      }
2179
2180      else if (remainder_size >= 0) /* exact fit */
2181      {
2182        unlink(victim, bck, fwd);
2183        set_inuse_bit_at_offset(victim, victim_size);
2184        check_malloced_chunk(victim, nb);
2185        return chunk2mem(victim);
2186      }
2187    }
2188
2189    ++idx; 
2190
2191  }
2192
2193  /* Try to use the last split-off remainder */
2194
2195  if ( (victim = last_remainder->fd) != last_remainder)
2196  {
2197    victim_size = chunksize(victim);
2198    remainder_size = victim_size - nb;
2199
2200    if (remainder_size >= (long)MINSIZE) /* re-split */
2201    {
2202      remainder = chunk_at_offset(victim, nb);
2203      set_head(victim, nb | PREV_INUSE);
2204      link_last_remainder(remainder);
2205      set_head(remainder, remainder_size | PREV_INUSE);
2206      set_foot(remainder, remainder_size);
2207      check_malloced_chunk(victim, nb);
2208      return chunk2mem(victim);
2209    }
2210
2211    clear_last_remainder;
2212
2213    if (remainder_size >= 0)  /* exhaust */
2214    {
2215      set_inuse_bit_at_offset(victim, victim_size);
2216      check_malloced_chunk(victim, nb);
2217      return chunk2mem(victim);
2218    }
2219
2220    /* Else place in bin */
2221
2222    frontlink(victim, victim_size, remainder_index, bck, fwd);
2223  }
2224
2225  /*
2226     If there are any possibly nonempty big-enough blocks,
2227     search for best fitting chunk by scanning bins in blockwidth units.
2228  */
2229
2230  if ( (block = idx2binblock(idx)) <= binblocks) 
2231  {
2232
2233    /* Get to the first marked block */
2234
2235    if ( (block & binblocks) == 0) 
2236    {
2237      /* force to an even block boundary */
2238      idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH;
2239      block <<= 1;
2240      while ((block & binblocks) == 0)
2241      {
2242        idx += BINBLOCKWIDTH;
2243        block <<= 1;
2244      }
2245    }
2246     
2247    /* For each possibly nonempty block ... */
2248    for (;;) 
2249    {
2250      startidx = idx;          /* (track incomplete blocks) */
2251      q = bin = bin_at(idx);
2252
2253      /* For each bin in this block ... */
2254      do
2255      {
2256        /* Find and use first big enough chunk ... */
2257
2258        for (victim = last(bin); victim != bin; victim = victim->bk)
2259        {
2260          victim_size = chunksize(victim);
2261          remainder_size = victim_size - nb;
2262
2263          if (remainder_size >= (long)MINSIZE) /* split */
2264          {
2265            remainder = chunk_at_offset(victim, nb);
2266            set_head(victim, nb | PREV_INUSE);
2267            unlink(victim, bck, fwd);
2268            link_last_remainder(remainder);
2269            set_head(remainder, remainder_size | PREV_INUSE);
2270            set_foot(remainder, remainder_size);
2271            check_malloced_chunk(victim, nb);
2272            return chunk2mem(victim);
2273          }
2274
2275          else if (remainder_size >= 0)  /* take */
2276          {
2277            set_inuse_bit_at_offset(victim, victim_size);
2278            unlink(victim, bck, fwd);
2279            check_malloced_chunk(victim, nb);
2280            return chunk2mem(victim);
2281          }
2282
2283        }
2284
2285       bin = next_bin(bin);
2286
2287      } while ((++idx & (BINBLOCKWIDTH - 1)) != 0);
2288
2289      /* Clear out the block bit. */
2290
2291      do   /* Possibly backtrack to try to clear a partial block */
2292      {
2293        if ((startidx & (BINBLOCKWIDTH - 1)) == 0)
2294        {
2295          binblocks &= ~block;
2296          break;
2297        }
2298        --startidx;
2299       q = prev_bin(q);
2300      } while (first(q) == q);
2301
2302      /* Get to the next possibly nonempty block */
2303
2304      if ( (block <<= 1) <= binblocks && (block != 0) ) 
2305      {
2306        while ((block & binblocks) == 0)
2307        {
2308          idx += BINBLOCKWIDTH;
2309          block <<= 1;
2310        }
2311      }
2312      else
2313        break;
2314    }
2315  }
2316
2317
2318  /* Try to use top chunk */
2319
2320  /* Require that there be a remainder, ensuring top always exists  */
2321  if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE)
2322  {
2323
2324#if HAVE_MMAP
2325    /* If big and would otherwise need to extend, try to use mmap instead */
2326    if ((unsigned long)nb >= (unsigned long)mmap_threshold &&
2327        (victim = mmap_chunk(nb)) != 0)
2328      return chunk2mem(victim);
2329#endif
2330
2331    /* Try to extend */
2332    malloc_extend_top(nb);
2333    if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE)
2334      return 0; /* propagate failure */
2335  }
2336
2337  victim = top;
2338  set_head(victim, nb | PREV_INUSE);
2339  top = chunk_at_offset(victim, nb);
2340  set_head(top, remainder_size | PREV_INUSE);
2341  check_malloced_chunk(victim, nb);
2342  return chunk2mem(victim);
2343
2344}
2345
2346
2347
2348
2349/*
2350
2351  free() algorithm :
2352
2353    cases:
2354
2355       1. free(0) has no effect. 
2356
2357       2. If the chunk was allocated via mmap, it is release via munmap().
2358
2359       3. If a returned chunk borders the current high end of memory,
2360          it is consolidated into the top, and if the total unused
2361          topmost memory exceeds the trim threshold, malloc_trim is
2362          called.
2363
2364       4. Other chunks are consolidated as they arrive, and
2365          placed in corresponding bins. (This includes the case of
2366          consolidating with the current `last_remainder').
2367
2368*/
2369
2370
2371#if __STD_C
2372void fREe(Void_t* mem)
2373#else
2374void fREe(mem) Void_t* mem;
2375#endif
2376{
2377  mchunkptr p;         /* chunk corresponding to mem */
2378  INTERNAL_SIZE_T hd;  /* its head field */
2379  INTERNAL_SIZE_T sz;  /* its size */
2380  int       idx;       /* its bin index */
2381  mchunkptr next;      /* next contiguous chunk */
2382  INTERNAL_SIZE_T nextsz; /* its size */
2383  INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */
2384  mchunkptr bck;       /* misc temp for linking */
2385  mchunkptr fwd;       /* misc temp for linking */
2386  int       islr;      /* track whether merging with last_remainder */
2387
2388  if (mem == 0)                              /* free(0) has no effect */
2389    return;
2390
2391  p = mem2chunk(mem);
2392  hd = p->size;
2393
2394#if HAVE_MMAP
2395  if (hd & IS_MMAPPED)                       /* release mmapped memory. */
2396  {
2397    munmap_chunk(p);
2398    return;
2399  }
2400#endif
2401 
2402  check_inuse_chunk(p);
2403 
2404  sz = hd & ~PREV_INUSE;
2405  next = chunk_at_offset(p, sz);
2406  nextsz = chunksize(next);
2407 
2408  if (next == top)                            /* merge with top */
2409  {
2410    sz += nextsz;
2411
2412    if (!(hd & PREV_INUSE))                    /* consolidate backward */
2413    {
2414      prevsz = p->prev_size;
2415      p = chunk_at_offset(p, -((long) prevsz));
2416      sz += prevsz;
2417      unlink(p, bck, fwd);
2418    }
2419
2420    set_head(p, sz | PREV_INUSE);
2421    top = p;
2422    if ((unsigned long)(sz) >= (unsigned long)trim_threshold) 
2423      malloc_trim(top_pad); 
2424    return;
2425  }
2426
2427  set_head(next, nextsz);                    /* clear inuse bit */
2428
2429  islr = 0;
2430
2431  if (!(hd & PREV_INUSE))                    /* consolidate backward */
2432  {
2433    prevsz = p->prev_size;
2434    p = chunk_at_offset(p, -((long) prevsz));
2435    sz += prevsz;
2436   
2437    if (p->fd == last_remainder)             /* keep as last_remainder */
2438      islr = 1;
2439    else
2440      unlink(p, bck, fwd);
2441  }
2442 
2443  if (!(inuse_bit_at_offset(next, nextsz)))   /* consolidate forward */
2444  {
2445    sz += nextsz;
2446   
2447    if (!islr && next->fd == last_remainder)  /* re-insert last_remainder */
2448    {
2449      islr = 1;
2450      link_last_remainder(p);   
2451    }
2452    else
2453      unlink(next, bck, fwd);
2454  }
2455
2456
2457  set_head(p, sz | PREV_INUSE);
2458  set_foot(p, sz);
2459  if (!islr)
2460    frontlink(p, sz, idx, bck, fwd); 
2461}
2462
2463
2464
2465
2466
2467/*
2468
2469  Realloc algorithm:
2470
2471    Chunks that were obtained via mmap cannot be extended or shrunk
2472    unless HAVE_MREMAP is defined, in which case mremap is used.
2473    Otherwise, if their reallocation is for additional space, they are
2474    copied.  If for less, they are just left alone.
2475
2476    Otherwise, if the reallocation is for additional space, and the
2477    chunk can be extended, it is, else a malloc-copy-free sequence is
2478    taken.  There are several different ways that a chunk could be
2479    extended. All are tried:
2480
2481       * Extending forward into following adjacent free chunk.
2482       * Shifting backwards, joining preceding adjacent space
2483       * Both shifting backwards and extending forward.
2484       * Extending into newly sbrked space
2485
2486    Unless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with a
2487    size argument of zero (re)allocates a minimum-sized chunk.
2488
2489    If the reallocation is for less space, and the new request is for
2490    a `small' (<512 bytes) size, then the newly unused space is lopped
2491    off and freed.
2492
2493    The old unix realloc convention of allowing the last-free'd chunk
2494    to be used as an argument to realloc is no longer supported.
2495    I don't know of any programs still relying on this feature,
2496    and allowing it would also allow too many other incorrect
2497    usages of realloc to be sensible.
2498
2499
2500*/
2501
2502
2503#if __STD_C
2504Void_t* rEALLOc(Void_t* oldmem, size_t bytes)
2505#else
2506Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes;
2507#endif
2508{
2509  INTERNAL_SIZE_T    nb;      /* padded request size */
2510
2511  mchunkptr oldp;             /* chunk corresponding to oldmem */
2512  INTERNAL_SIZE_T    oldsize; /* its size */
2513
2514  mchunkptr newp;             /* chunk to return */
2515  INTERNAL_SIZE_T    newsize; /* its size */
2516  Void_t*   newmem;           /* corresponding user mem */
2517
2518  mchunkptr next;             /* next contiguous chunk after oldp */
2519  INTERNAL_SIZE_T  nextsize;  /* its size */
2520
2521  mchunkptr prev;             /* previous contiguous chunk before oldp */
2522  INTERNAL_SIZE_T  prevsize;  /* its size */
2523
2524  mchunkptr remainder;        /* holds split off extra space from newp */
2525  INTERNAL_SIZE_T  remainder_size;   /* its size */
2526
2527  mchunkptr bck;              /* misc temp for linking */
2528  mchunkptr fwd;              /* misc temp for linking */
2529
2530#ifdef REALLOC_ZERO_BYTES_FREES
2531  if (bytes == 0) { fREe(oldmem); return 0; }
2532#endif
2533
2534  if ((long)bytes < 0) return 0;
2535
2536  /* realloc of null is supposed to be same as malloc */
2537  if (oldmem == 0) return mALLOc(bytes);
2538
2539  newp    = oldp    = mem2chunk(oldmem);
2540  newsize = oldsize = chunksize(oldp);
2541
2542
2543  nb = request2size(bytes);
2544
2545#if HAVE_MMAP
2546  if (chunk_is_mmapped(oldp)) 
2547  {
2548#if HAVE_MREMAP
2549    newp = mremap_chunk(oldp, nb);
2550    if(newp) return chunk2mem(newp);
2551#endif
2552    /* Note the extra SIZE_SZ overhead. */
2553    if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing */
2554    /* Must alloc, copy, free. */
2555    newmem = mALLOc(bytes);
2556    if (newmem == 0) return 0; /* propagate failure */
2557    MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ);
2558    munmap_chunk(oldp);
2559    return newmem;
2560  }
2561#endif
2562
2563  check_inuse_chunk(oldp);
2564
2565  if ((long)(oldsize) < (long)(nb)) 
2566  {
2567
2568    /* Try expanding forward */
2569
2570    next = chunk_at_offset(oldp, oldsize);
2571    if (next == top || !inuse(next)) 
2572    {
2573      nextsize = chunksize(next);
2574
2575      /* Forward into top only if a remainder */
2576      if (next == top)
2577      {
2578        if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE))
2579        {
2580          newsize += nextsize;
2581          top = chunk_at_offset(oldp, nb);
2582          set_head(top, (newsize - nb) | PREV_INUSE);
2583          set_head_size(oldp, nb);
2584          return chunk2mem(oldp);
2585        }
2586      }
2587
2588      /* Forward into next chunk */
2589      else if (((long)(nextsize + newsize) >= (long)(nb)))
2590      { 
2591        unlink(next, bck, fwd);
2592        newsize  += nextsize;
2593        goto split;
2594      }
2595    }
2596    else
2597    {
2598      next = 0;
2599      nextsize = 0;
2600    }
2601
2602    /* Try shifting backwards. */
2603
2604    if (!prev_inuse(oldp))
2605    {
2606      prev = prev_chunk(oldp);
2607      prevsize = chunksize(prev);
2608
2609      /* try forward + backward first to save a later consolidation */
2610
2611      if (next != 0)
2612      {
2613        /* into top */
2614        if (next == top)
2615        {
2616          if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE))
2617          {
2618            unlink(prev, bck, fwd);
2619            newp = prev;
2620            newsize += prevsize + nextsize;
2621            newmem = chunk2mem(newp);
2622            MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
2623            top = chunk_at_offset(newp, nb);
2624            set_head(top, (newsize - nb) | PREV_INUSE);
2625            set_head_size(newp, nb);
2626            return newmem;
2627          }
2628        }
2629
2630        /* into next chunk */
2631        else if (((long)(nextsize + prevsize + newsize) >= (long)(nb)))
2632        {
2633          unlink(next, bck, fwd);
2634          unlink(prev, bck, fwd);
2635          newp = prev;
2636          newsize += nextsize + prevsize;
2637          newmem = chunk2mem(newp);
2638          MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
2639          goto split;
2640        }
2641      }
2642     
2643      /* backward only */
2644      if (prev != 0 && (long)(prevsize + newsize) >= (long)nb) 
2645      {
2646        unlink(prev, bck, fwd);
2647        newp = prev;
2648        newsize += prevsize;
2649        newmem = chunk2mem(newp);
2650        MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
2651        goto split;
2652      }
2653    }
2654
2655    /* Must allocate */
2656
2657    newmem = mALLOc (bytes);
2658
2659    if (newmem == 0)  /* propagate failure */
2660      return 0; 
2661
2662    /* Avoid copy if newp is next chunk after oldp. */
2663    /* (This can only happen when new chunk is sbrk'ed.) */
2664
2665    if ( (newp = mem2chunk(newmem)) == next_chunk(oldp)) 
2666    {
2667      newsize += chunksize(newp);
2668      newp = oldp;
2669      goto split;
2670    }
2671
2672    /* Otherwise copy, free, and exit */
2673    MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ);
2674    fREe(oldmem);
2675    return newmem;
2676  }
2677
2678
2679 split:  /* split off extra room in old or expanded chunk */
2680
2681  if (newsize - nb >= MINSIZE) /* split off remainder */
2682  {
2683    remainder = chunk_at_offset(newp, nb);
2684    remainder_size = newsize - nb;
2685    set_head_size(newp, nb);
2686    set_head(remainder, remainder_size | PREV_INUSE);
2687    set_inuse_bit_at_offset(remainder, remainder_size);
2688    fREe(chunk2mem(remainder)); /* let free() deal with it */
2689  }
2690  else
2691  {
2692    set_head_size(newp, newsize);
2693    set_inuse_bit_at_offset(newp, newsize);
2694  }
2695
2696  check_inuse_chunk(newp);
2697  return chunk2mem(newp);
2698}
2699
2700
2701
2702
2703/*
2704
2705  memalign algorithm:
2706
2707    memalign requests more than enough space from malloc, finds a spot
2708    within that chunk that meets the alignment request, and then
2709    possibly frees the leading and trailing space.
2710
2711    The alignment argument must be a power of two. This property is not
2712    checked by memalign, so misuse may result in random runtime errors.
2713
2714    8-byte alignment is guaranteed by normal malloc calls, so don't
2715    bother calling memalign with an argument of 8 or less.
2716
2717    Overreliance on memalign is a sure way to fragment space.
2718
2719*/
2720
2721
2722#if __STD_C
2723Void_t* mEMALIGn(size_t alignment, size_t bytes)
2724#else
2725Void_t* mEMALIGn(alignment, bytes) size_t alignment; size_t bytes;
2726#endif
2727{
2728  INTERNAL_SIZE_T    nb;      /* padded  request size */
2729  char*     m;                /* memory returned by malloc call */
2730  mchunkptr p;                /* corresponding chunk */
2731  char*     brk;              /* alignment point within p */
2732  mchunkptr newp;             /* chunk to return */
2733  INTERNAL_SIZE_T  newsize;   /* its size */
2734  INTERNAL_SIZE_T  leadsize;  /* leading space befor alignment point */
2735  mchunkptr remainder;        /* spare room at end to split off */
2736  long      remainder_size;   /* its size */
2737
2738  if ((long)bytes < 0) return 0;
2739
2740  /* If need less alignment than we give anyway, just relay to malloc */
2741
2742  if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes);
2743
2744  /* Otherwise, ensure that it is at least a minimum chunk size */
2745 
2746  if (alignment <  MINSIZE) alignment = MINSIZE;
2747
2748  /* Call malloc with worst case padding to hit alignment. */
2749
2750  nb = request2size(bytes);
2751  m  = (char*)(mALLOc(nb + alignment + MINSIZE));
2752
2753  if (m == 0) return 0; /* propagate failure */
2754
2755  p = mem2chunk(m);
2756
2757  if ((((unsigned long)(m)) % alignment) == 0) /* aligned */
2758  {
2759#if HAVE_MMAP
2760    if(chunk_is_mmapped(p))
2761      return chunk2mem(p); /* nothing more to do */
2762#endif
2763  }
2764  else /* misaligned */
2765  {
2766    /*
2767      Find an aligned spot inside chunk.
2768      Since we need to give back leading space in a chunk of at
2769      least MINSIZE, if the first calculation places us at
2770      a spot with less than MINSIZE leader, we can move to the
2771      next aligned spot -- we've allocated enough total room so that
2772      this is always possible.
2773    */
2774
2775    brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) & -((signed) alignment));
2776    if ((long)(brk - (char*)(p)) < MINSIZE) brk = brk + alignment;
2777
2778    newp = (mchunkptr)brk;
2779    leadsize = brk - (char*)(p);
2780    newsize = chunksize(p) - leadsize;
2781
2782#if HAVE_MMAP
2783    if(chunk_is_mmapped(p)) 
2784    {
2785      newp->prev_size = p->prev_size + leadsize;
2786      set_head(newp, newsize|IS_MMAPPED);
2787      return chunk2mem(newp);
2788    }
2789#endif
2790
2791    /* give back leader, use the rest */
2792
2793    set_head(newp, newsize | PREV_INUSE);
2794    set_inuse_bit_at_offset(newp, newsize);
2795    set_head_size(p, leadsize);
2796    fREe(chunk2mem(p));
2797    p = newp;
2798
2799    assert (newsize >= nb && (((unsigned long)(chunk2mem(p))) % alignment) == 0);
2800  }
2801
2802  /* Also give back spare room at the end */
2803
2804  remainder_size = chunksize(p) - nb;
2805
2806  if (remainder_size >= (long)MINSIZE)
2807  {
2808    remainder = chunk_at_offset(p, nb);
2809    set_head(remainder, remainder_size | PREV_INUSE);
2810    set_head_size(p, nb);
2811    fREe(chunk2mem(remainder));
2812  }
2813
2814  check_inuse_chunk(p);
2815  return chunk2mem(p);
2816
2817}
2818
2819
2820
2821
2822/*
2823    valloc just invokes memalign with alignment argument equal
2824    to the page size of the system (or as near to this as can
2825    be figured out from all the includes/defines above.)
2826*/
2827
2828#if __STD_C
2829Void_t* vALLOc(size_t bytes)
2830#else
2831Void_t* vALLOc(bytes) size_t bytes;
2832#endif
2833{
2834  return mEMALIGn (malloc_getpagesize, bytes);
2835}
2836
2837/*
2838  pvalloc just invokes valloc for the nearest pagesize
2839  that will accommodate request
2840*/
2841
2842
2843#if __STD_C
2844Void_t* pvALLOc(size_t bytes)
2845#else
2846Void_t* pvALLOc(bytes) size_t bytes;
2847#endif
2848{
2849  size_t pagesize = malloc_getpagesize;
2850  return mEMALIGn (pagesize, (bytes + pagesize - 1) & ~(pagesize - 1));
2851}
2852
2853/*
2854
2855  calloc calls malloc, then zeroes out the allocated chunk.
2856
2857*/
2858
2859#if __STD_C
2860Void_t* cALLOc(size_t n, size_t elem_size)
2861#else
2862Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size;
2863#endif
2864{
2865  mchunkptr p;
2866  INTERNAL_SIZE_T csz;
2867
2868  INTERNAL_SIZE_T sz = n * elem_size;
2869
2870
2871  /* check if expand_top called, in which case don't need to clear */
2872#if MORECORE_CLEARS
2873  mchunkptr oldtop = top;
2874  INTERNAL_SIZE_T oldtopsize = chunksize(top);
2875#endif
2876  Void_t* mem = mALLOc (sz);
2877
2878  if ((long)n < 0) return 0;
2879
2880  if (mem == 0) 
2881    return 0;
2882  else
2883  {
2884    p = mem2chunk(mem);
2885
2886    /* Two optional cases in which clearing not necessary */
2887
2888
2889#if HAVE_MMAP
2890    if (chunk_is_mmapped(p)) return mem;
2891#endif
2892
2893    csz = chunksize(p);
2894
2895#if MORECORE_CLEARS
2896    if (p == oldtop && csz > oldtopsize) 
2897    {
2898      /* clear only the bytes from non-freshly-sbrked memory */
2899      csz = oldtopsize;
2900    }
2901#endif
2902
2903    MALLOC_ZERO(mem, csz - SIZE_SZ);
2904    return mem;
2905  }
2906}
2907
2908/*
2909 
2910  cfree just calls free. It is needed/defined on some systems
2911  that pair it with calloc, presumably for odd historical reasons.
2912
2913*/
2914
2915#if !defined(INTERNAL_LINUX_C_LIB) || !defined(__ELF__)
2916#if __STD_C
2917void cfree(Void_t *mem)
2918#else
2919void cfree(mem) Void_t *mem;
2920#endif
2921{
2922  fREe(mem);
2923}
2924#endif
2925
2926
2927
2928/*
2929
2930    Malloc_trim gives memory back to the system (via negative
2931    arguments to sbrk) if there is unused memory at the `high' end of
2932    the malloc pool. You can call this after freeing large blocks of
2933    memory to potentially reduce the system-level memory requirements
2934    of a program. However, it cannot guarantee to reduce memory. Under
2935    some allocation patterns, some large free blocks of memory will be
2936    locked between two used chunks, so they cannot be given back to
2937    the system.
2938
2939    The `pad' argument to malloc_trim represents the amount of free
2940    trailing space to leave untrimmed. If this argument is zero,
2941    only the minimum amount of memory to maintain internal data
2942    structures will be left (one page or less). Non-zero arguments
2943    can be supplied to maintain enough trailing space to service
2944    future expected allocations without having to re-obtain memory
2945    from the system.
2946
2947    Malloc_trim returns 1 if it actually released any memory, else 0.
2948
2949*/
2950
2951#if __STD_C
2952int malloc_trim(size_t pad)
2953#else
2954int malloc_trim(pad) size_t pad;
2955#endif
2956{
2957  long  top_size;        /* Amount of top-most memory */
2958  long  extra;           /* Amount to release */
2959  char* current_brk;     /* address returned by pre-check sbrk call */
2960  char* new_brk;         /* address returned by negative sbrk call */
2961
2962  unsigned long pagesz = malloc_getpagesize;
2963
2964  top_size = chunksize(top);
2965  extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz;
2966
2967  if (extra < (long)pagesz)  /* Not enough memory to release */
2968    return 0;
2969
2970  else
2971  {
2972    /* Test to make sure no one else called sbrk */
2973    current_brk = (char*)(MORECORE (0));
2974    if (current_brk != (char*)(top) + top_size)
2975      return 0;     /* Apparently we don't own memory; must fail */
2976
2977    else
2978    {
2979      new_brk = (char*)(MORECORE (-extra));
2980     
2981      if (new_brk == (char*)(MORECORE_FAILURE)) /* sbrk failed? */
2982      {
2983        /* Try to figure out what we have */
2984        current_brk = (char*)(MORECORE (0));
2985        top_size = current_brk - (char*)top;
2986        if (top_size >= (long)MINSIZE) /* if not, we are very very dead! */
2987        {
2988          sbrked_mem = current_brk - sbrk_base;
2989          set_head(top, top_size | PREV_INUSE);
2990        }
2991        check_chunk(top);
2992        return 0; 
2993      }
2994
2995      else
2996      {
2997        /* Success. Adjust top accordingly. */
2998        set_head(top, (top_size - extra) | PREV_INUSE);
2999        sbrked_mem -= extra;
3000        check_chunk(top);
3001        return 1;
3002      }
3003    }
3004  }
3005}
3006
3007
3008
3009/*
3010  malloc_usable_size:
3011
3012    This routine tells you how many bytes you can actually use in an
3013    allocated chunk, which may be more than you requested (although
3014    often not). You can use this many bytes without worrying about
3015    overwriting other allocated objects. Not a particularly great
3016    programming practice, but still sometimes useful.
3017
3018*/
3019
3020#if __STD_C
3021size_t malloc_usable_size(Void_t* mem)
3022#else
3023size_t malloc_usable_size(mem) Void_t* mem;
3024#endif
3025{
3026  mchunkptr p;
3027  if (mem == 0)
3028    return 0;
3029  else
3030  {
3031    p = mem2chunk(mem);
3032    if(!chunk_is_mmapped(p))
3033    {
3034      if (!inuse(p)) return 0;
3035      check_inuse_chunk(p);
3036      return chunksize(p) - SIZE_SZ;
3037    }
3038    return chunksize(p) - 2*SIZE_SZ;
3039  }
3040}
3041
3042
3043
3044
3045/* Utility to update current_mallinfo for malloc_stats and mallinfo() */
3046
3047static void malloc_update_mallinfo() 
3048{
3049  int i;
3050  mbinptr b;
3051  mchunkptr p;
3052#if DEBUG
3053  mchunkptr q;
3054#endif
3055
3056  INTERNAL_SIZE_T avail = chunksize(top);
3057  int   navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0;
3058
3059  for (i = 1; i < NAV; ++i)
3060  {
3061    b = bin_at(i);
3062    for (p = last(b); p != b; p = p->bk) 
3063    {
3064#if DEBUG
3065      check_free_chunk(p);
3066      for (q = next_chunk(p); 
3067           q < top && inuse(q) && (long)(chunksize(q)) >= (long)MINSIZE; 
3068           q = next_chunk(q))
3069        check_inuse_chunk(q);
3070#endif
3071      avail += chunksize(p);
3072      navail++;
3073    }
3074  }
3075
3076  current_mallinfo.ordblks = navail;
3077  current_mallinfo.uordblks = sbrked_mem - avail;
3078  current_mallinfo.fordblks = avail;
3079  current_mallinfo.hblks = n_mmaps;
3080  current_mallinfo.hblkhd = mmapped_mem;
3081  current_mallinfo.keepcost = chunksize(top);
3082
3083}
3084
3085
3086
3087/*
3088
3089  malloc_stats:
3090
3091    Prints on stderr the amount of space obtain from the system (both
3092    via sbrk and mmap), the maximum amount (which may be more than
3093    current if malloc_trim and/or munmap got called), the maximum
3094    number of simultaneous mmap regions used, and the current number
3095    of bytes allocated via malloc (or realloc, etc) but not yet
3096    freed. (Note that this is the number of bytes allocated, not the
3097    number requested. It will be larger than the number requested
3098    because of alignment and bookkeeping overhead.)
3099
3100*/
3101
3102void malloc_stats()
3103{
3104  malloc_update_mallinfo();
3105  fprintf(stderr, "max system bytes = %10u\n", 
3106          (unsigned int)(max_total_mem));
3107  fprintf(stderr, "system bytes     = %10u\n", 
3108          (unsigned int)(sbrked_mem + mmapped_mem));
3109  fprintf(stderr, "in use bytes     = %10u\n", 
3110          (unsigned int)(current_mallinfo.uordblks + mmapped_mem));
3111#if HAVE_MMAP
3112  fprintf(stderr, "max mmap regions = %10u\n", 
3113          (unsigned int)max_n_mmaps);
3114#endif
3115}
3116
3117/*
3118  mallinfo returns a copy of updated current mallinfo.
3119*/
3120
3121struct mallinfo mALLINFo()
3122{
3123  malloc_update_mallinfo();
3124  return current_mallinfo;
3125}
3126
3127
3128
3129
3130/*
3131  mallopt:
3132
3133    mallopt is the general SVID/XPG interface to tunable parameters.
3134    The format is to provide a (parameter-number, parameter-value) pair.
3135    mallopt then sets the corresponding parameter to the argument
3136    value if it can (i.e., so long as the value is meaningful),
3137    and returns 1 if successful else 0.
3138
3139    See descriptions of tunable parameters above.
3140
3141*/
3142
3143#if __STD_C
3144int mALLOPt(int param_number, int value)
3145#else
3146int mALLOPt(param_number, value) int param_number; int value;
3147#endif
3148{
3149  switch(param_number) 
3150  {
3151    case M_TRIM_THRESHOLD:
3152      trim_threshold = value; return 1; 
3153    case M_TOP_PAD:
3154      top_pad = value; return 1; 
3155    case M_MMAP_THRESHOLD:
3156      mmap_threshold = value; return 1;
3157    case M_MMAP_MAX:
3158#if HAVE_MMAP
3159      n_mmaps_max = value; return 1;
3160#else
3161      if (value != 0) return 0; else  n_mmaps_max = value; return 1;
3162#endif
3163
3164    default:
3165      return 0;
3166  }
3167}
3168
3169/*
3170
3171History:
3172
3173    V2.6.6 Sun Dec  5 07:42:19 1999  Doug Lea  (dl at gee)
3174      * return null for negative arguments
3175      * Added Several WIN32 cleanups from Martin C. Fong <mcfong@yahoo.com>
3176         * Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h'
3177          (e.g. WIN32 platforms)
3178         * Cleanup up header file inclusion for WIN32 platforms
3179         * Cleanup code to avoid Microsoft Visual C++ compiler complaints
3180         * Add 'USE_DL_PREFIX' to quickly allow co-existence with existing
3181           memory allocation routines
3182         * Set 'malloc_getpagesize' for WIN32 platforms (needs more work)
3183         * Use 'assert' rather than 'ASSERT' in WIN32 code to conform to
3184           usage of 'assert' in non-WIN32 code
3185         * Improve WIN32 'sbrk()' emulation's 'findRegion()' routine to
3186           avoid infinite loop
3187      * Always call 'fREe()' rather than 'free()'
3188
3189    V2.6.5 Wed Jun 17 15:57:31 1998  Doug Lea  (dl at gee)
3190      * Fixed ordering problem with boundary-stamping
3191
3192    V2.6.3 Sun May 19 08:17:58 1996  Doug Lea  (dl at gee)
3193      * Added pvalloc, as recommended by H.J. Liu
3194      * Added 64bit pointer support mainly from Wolfram Gloger
3195      * Added anonymously donated WIN32 sbrk emulation
3196      * Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen
3197      * malloc_extend_top: fix mask error that caused wastage after
3198        foreign sbrks
3199      * Add linux mremap support code from HJ Liu
3200   
3201    V2.6.2 Tue Dec  5 06:52:55 1995  Doug Lea  (dl at gee)
3202      * Integrated most documentation with the code.
3203      * Add support for mmap, with help from
3204        Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
3205      * Use last_remainder in more cases.
3206      * Pack bins using idea from  colin@nyx10.cs.du.edu
3207      * Use ordered bins instead of best-fit threshhold
3208      * Eliminate block-local decls to simplify tracing and debugging.
3209      * Support another case of realloc via move into top
3210      * Fix error occuring when initial sbrk_base not word-aligned. 
3211      * Rely on page size for units instead of SBRK_UNIT to
3212        avoid surprises about sbrk alignment conventions.
3213      * Add mallinfo, mallopt. Thanks to Raymond Nijssen
3214        (raymond@es.ele.tue.nl) for the suggestion.
3215      * Add `pad' argument to malloc_trim and top_pad mallopt parameter.
3216      * More precautions for cases where other routines call sbrk,
3217        courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de).
3218      * Added macros etc., allowing use in linux libc from
3219        H.J. Lu (hjl@gnu.ai.mit.edu)
3220      * Inverted this history list
3221
3222    V2.6.1 Sat Dec  2 14:10:57 1995  Doug Lea  (dl at gee)
3223      * Re-tuned and fixed to behave more nicely with V2.6.0 changes.
3224      * Removed all preallocation code since under current scheme
3225        the work required to undo bad preallocations exceeds
3226        the work saved in good cases for most test programs.
3227      * No longer use return list or unconsolidated bins since
3228        no scheme using them consistently outperforms those that don't
3229        given above changes.
3230      * Use best fit for very large chunks to prevent some worst-cases.
3231      * Added some support for debugging
3232
3233    V2.6.0 Sat Nov  4 07:05:23 1995  Doug Lea  (dl at gee)
3234      * Removed footers when chunks are in use. Thanks to
3235        Paul Wilson (wilson@cs.texas.edu) for the suggestion.
3236
3237    V2.5.4 Wed Nov  1 07:54:51 1995  Doug Lea  (dl at gee)
3238      * Added malloc_trim, with help from Wolfram Gloger
3239        (wmglo@Dent.MED.Uni-Muenchen.DE).
3240
3241    V2.5.3 Tue Apr 26 10:16:01 1994  Doug Lea  (dl at g)
3242
3243    V2.5.2 Tue Apr  5 16:20:40 1994  Doug Lea  (dl at g)
3244      * realloc: try to expand in both directions
3245      * malloc: swap order of clean-bin strategy;
3246      * realloc: only conditionally expand backwards
3247      * Try not to scavenge used bins
3248      * Use bin counts as a guide to preallocation
3249      * Occasionally bin return list chunks in first scan
3250      * Add a few optimizations from colin@nyx10.cs.du.edu
3251
3252    V2.5.1 Sat Aug 14 15:40:43 1993  Doug Lea  (dl at g)
3253      * faster bin computation & slightly different binning
3254      * merged all consolidations to one part of malloc proper
3255         (eliminating old malloc_find_space & malloc_clean_bin)
3256      * Scan 2 returns chunks (not just 1)
3257      * Propagate failure in realloc if malloc returns 0
3258      * Add stuff to allow compilation on non-ANSI compilers
3259          from kpv@research.att.com
3260     
3261    V2.5 Sat Aug  7 07:41:59 1993  Doug Lea  (dl at g.oswego.edu)
3262      * removed potential for odd address access in prev_chunk
3263      * removed dependency on getpagesize.h
3264      * misc cosmetics and a bit more internal documentation
3265      * anticosmetics: mangled names in macros to evade debugger strangeness
3266      * tested on sparc, hp-700, dec-mips, rs6000
3267          with gcc & native cc (hp, dec only) allowing
3268          Detlefs & Zorn comparison study (in SIGPLAN Notices.)
3269
3270    Trial version Fri Aug 28 13:14:29 1992  Doug Lea  (dl at g.oswego.edu)
3271      * Based loosely on libg++-1.2X malloc. (It retains some of the overall
3272         structure of old version,  but most details differ.)
3273
3274*/
3275
3276
Note: See TracBrowser for help on using the repository browser.