Context Navigation

← Previous Revision
Latest Revision
Next Revision →
Blame
Revision Log

dlmalloc-2.6.6.c @ 1

Last change on this file since 1 was 1, checked in by Tim Harvey, 3 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
252	extern "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
370	void* memset(void*, int, size_t);
371	void* 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
377	Void_t* memset();
378	Void_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) \
390	do { \
391	INTERNAL_SIZE_T mzsz = (nbytes); \
392	if(mzsz <= 9*sizeof(mzsz)) { \
393	INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \
394	if(mzsz >= 5sizeof(mzsz)) { mz++ = 0; \
395	*mz++ = 0; \
396	if(mzsz >= 7sizeof(mzsz)) { mz++ = 0; \
397	*mz++ = 0; \
398	if(mzsz >= 9sizeof(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) \
407	do { \
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 >= 5sizeof(mcsz)) { mcdst++ = *mcsrc++; \
413	mcdst++ = mcsrc++; \
414	if(mcsz >= 7sizeof(mcsz)) { mcdst++ = *mcsrc++; \
415	mcdst++ = mcsrc++; \
416	if(mcsz >= 9sizeof(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) \
429	do { \
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) \
446	do { \
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
594	struct 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
818	Void_t * __default_morecore_init (ptrdiff_t);
819	Void_t (__morecore)(ptrdiff_t) = __default_morecore_init;
820
821	#else
822
823	Void_t * __default_morecore_init ();
824	Void_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
835	extern Void_t* sbrk(ptrdiff_t);
836	#else
837	extern 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
907	Void_t* mALLOc(size_t);
908	void fREe(Void_t*);
909	Void_t* rEALLOc(Void_t*, size_t);
910	Void_t* mEMALIGn(size_t, size_t);
911	Void_t* vALLOc(size_t);
912	Void_t* pvALLOc(size_t);
913	Void_t* cALLOc(size_t, size_t);
914	void cfree(Void_t*);
915	int malloc_trim(size_t);
916	size_t malloc_usable_size(Void_t*);
917	void malloc_stats();
918	int mALLOPt(int, int);
919	struct mallinfo mALLINFo(void);
920	#else
921	Void_t* mALLOc();
922	void fREe();
923	Void_t* rEALLOc();
924	Void_t* mEMALIGn();
925	Void_t* vALLOc();
926	Void_t* pvALLOc();
927	Void_t* cALLOc();
928	void cfree();
929	int malloc_trim();
930	size_t malloc_usable_size();
931	void malloc_stats();
932	int mALLOPt();
933	struct 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 (1024102464)
960	#define NEXT_SIZE (2048*1024)
961	#define TOP_MEMORY ((unsigned long)210241024*1024)
962
963	struct GmListElement;
964	typedef struct GmListElement GmListElement;
965
966	struct GmListElement
967	{
968	GmListElement* next;
969	void* base;
970	};
971
972	static GmListElement* head = 0;
973	static unsigned int gNextAddress = 0;
974	static unsigned int gAddressBase = 0;
975	static unsigned int gAllocatedSize = 0;
976
977	static
978	GmListElement* 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
992	void 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
1013	static
1014	void* 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
1054	void* 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 +
1066	gAllocatedSize))
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
1141	struct 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
1149	typedef 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	. \|
1178	nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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	. \|
1205	nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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) - 2SIZE_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
1440	typedef 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
1471	static 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
1557	static unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD;
1558	static unsigned long top_pad = DEFAULT_TOP_PAD;
1559	static unsigned int n_mmaps_max = DEFAULT_MMAP_MAX;
1560	static unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD;
1561
1562	/* The first value returned from sbrk */
1563	static char* sbrk_base = (char*)(-1);
1564
1565	/* The maximum memory obtained from system via sbrk */
1566	static unsigned long max_sbrked_mem = 0;
1567
1568	/* The maximum via either sbrk or mmap */
1569	static unsigned long max_total_mem = 0;
1570
1571	/* internal working copy of mallinfo */
1572	static 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
1579	static unsigned int n_mmaps = 0;
1580	static unsigned int max_n_mmaps = 0;
1581	static unsigned long mmapped_mem = 0;
1582	static 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
1602	static void do_check_chunk(mchunkptr p)
1603	#else
1604	static 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
1623	static void do_check_free_chunk(mchunkptr p)
1624	#else
1625	static 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
1656	static void do_check_inuse_chunk(mchunkptr p)
1657	#else
1658	static 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
1688	static void do_check_malloced_chunk(mchunkptr p, INTERNAL_SIZE_T s)
1689	#else
1690	static 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
1806	static mchunkptr mmap_chunk(size_t size)
1807	#else
1808	static 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
1861	static void munmap_chunk(mchunkptr p)
1862	#else
1863	static 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
1886	static mchunkptr mremap_chunk(mchunkptr p, size_t new_size)
1887	#else
1888	static 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
1937	static void malloc_extend_top(INTERNAL_SIZE_T nb)
1938	#else
1939	static 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
2111	Void_t* mALLOc(size_t bytes)
2112	#else
2113	Void_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
2372	void fREe(Void_t* mem)
2373	#else
2374	void 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
2504	Void_t* rEALLOc(Void_t* oldmem, size_t bytes)
2505	#else
2506	Void_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
2723	Void_t* mEMALIGn(size_t alignment, size_t bytes)
2724	#else
2725	Void_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
2829	Void_t* vALLOc(size_t bytes)
2830	#else
2831	Void_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
2844	Void_t* pvALLOc(size_t bytes)
2845	#else
2846	Void_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
2860	Void_t* cALLOc(size_t n, size_t elem_size)
2861	#else
2862	Void_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
2917	void cfree(Void_t *mem)
2918	#else
2919	void 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
2952	int malloc_trim(size_t pad)
2953	#else
2954	int 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
3021	size_t malloc_usable_size(Void_t* mem)
3022	#else
3023	size_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
3047	static 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
3102	void 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
3121	struct 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
3144	int mALLOPt(int param_number, int value)
3145	#else
3146	int 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
3171	History:
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.

Context Navigation

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

Download in other formats: