1/* ---------- To make a malloc.h, start cutting here ------------ */ 2 3/* 4 A version of malloc/free/realloc written by Doug Lea and released to the 5 public domain. Send questions/comments/complaints/performance data 6 to dl@cs.oswego.edu 7 8* VERSION 2.6.6 Sun Mar 5 19:10:03 2000 Doug Lea (dl at gee) 9 10 Note: There may be an updated version of this malloc obtainable at 11 ftp://g.oswego.edu/pub/misc/malloc.c 12 Check before installing! 13 14* Why use this malloc? 15 16 This is not the fastest, most space-conserving, most portable, or 17 most tunable malloc ever written. However it is among the fastest 18 while also being among the most space-conserving, portable and tunable. 19 Consistent balance across these factors results in a good general-purpose 20 allocator. For a high-level description, see 21 http://g.oswego.edu/dl/html/malloc.html 22 23* Synopsis of public routines 24 25 (Much fuller descriptions are contained in the program documentation below.) 26 27 malloc(size_t n); 28 Return a pointer to a newly allocated chunk of at least n bytes, or null 29 if no space is available. 30 free(Void_t* p); 31 Release the chunk of memory pointed to by p, or no effect if p is null. 32 realloc(Void_t* p, size_t n); 33 Return a pointer to a chunk of size n that contains the same data 34 as does chunk p up to the minimum of (n, p's size) bytes, or null 35 if no space is available. The returned pointer may or may not be 36 the same as p. If p is null, equivalent to malloc. Unless the 37 #define REALLOC_ZERO_BYTES_FREES below is set, realloc with a 38 size argument of zero (re)allocates a minimum-sized chunk. 39 memalign(size_t alignment, size_t n); 40 Return a pointer to a newly allocated chunk of n bytes, aligned 41 in accord with the alignment argument, which must be a power of 42 two. 43 valloc(size_t n); 44 Equivalent to memalign(pagesize, n), where pagesize is the page 45 size of the system (or as near to this as can be figured out from 46 all the includes/defines below.) 47 pvalloc(size_t n); 48 Equivalent to valloc(minimum-page-that-holds(n)), that is, 49 round up n to nearest pagesize. 50 calloc(size_t unit, size_t quantity); 51 Returns a pointer to quantity * unit bytes, with all locations 52 set to zero. 53 cfree(Void_t* p); 54 Equivalent to free(p). 55 malloc_trim(size_t pad); 56 Release all but pad bytes of freed top-most memory back 57 to the system. Return 1 if successful, else 0. 58 malloc_usable_size(Void_t* p); 59 Report the number usable allocated bytes associated with allocated 60 chunk p. This may or may not report more bytes than were requested, 61 due to alignment and minimum size constraints. 62 malloc_stats(); 63 Prints brief summary statistics on stderr. 64 mallinfo() 65 Returns (by copy) a struct containing various summary statistics. 66 mallopt(int parameter_number, int parameter_value) 67 Changes one of the tunable parameters described below. Returns 68 1 if successful in changing the parameter, else 0. 69 70* Vital statistics: 71 72 Alignment: 8-byte 73 8 byte alignment is currently hardwired into the design. This 74 seems to suffice for all current machines and C compilers. 75 76 Assumed pointer representation: 4 or 8 bytes 77 Code for 8-byte pointers is untested by me but has worked 78 reliably by Wolfram Gloger, who contributed most of the 79 changes supporting this. 80 81 Assumed size_t representation: 4 or 8 bytes 82 Note that size_t is allowed to be 4 bytes even if pointers are 8. 83 84 Minimum overhead per allocated chunk: 4 or 8 bytes 85 Each malloced chunk has a hidden overhead of 4 bytes holding size 86 and status information. 87 88 Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead) 89 8-byte ptrs: 24/32 bytes (including, 4/8 overhead) 90 91 When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte 92 ptrs but 4 byte size) or 24 (for 8/8) additional bytes are 93 needed; 4 (8) for a trailing size field 94 and 8 (16) bytes for free list pointers. Thus, the minimum 95 allocatable size is 16/24/32 bytes. 96 97 Even a request for zero bytes (i.e., malloc(0)) returns a 98 pointer to something of the minimum allocatable size. 99 100 Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes 101 8-byte size_t: 2^63 - 16 bytes 102 103 It is assumed that (possibly signed) size_t bit values suffice to 104 represent chunk sizes. `Possibly signed' is due to the fact 105 that `size_t' may be defined on a system as either a signed or 106 an unsigned type. To be conservative, values that would appear 107 as negative numbers are avoided. 108 Requests for sizes with a negative sign bit when the request 109 size is treaded as a long will return null. 110 111 Maximum overhead wastage per allocated chunk: normally 15 bytes 112 113 Alignnment demands, plus the minimum allocatable size restriction 114 make the normal worst-case wastage 15 bytes (i.e., up to 15 115 more bytes will be allocated than were requested in malloc), with 116 two exceptions: 117 1. Because requests for zero bytes allocate non-zero space, 118 the worst case wastage for a request of zero bytes is 24 bytes. 119 2. For requests >= mmap_threshold that are serviced via 120 mmap(), the worst case wastage is 8 bytes plus the remainder 121 from a system page (the minimal mmap unit); typically 4096 bytes. 122 123* Limitations 124 125 Here are some features that are NOT currently supported 126 127 * No user-definable hooks for callbacks and the like. 128 * No automated mechanism for fully checking that all accesses 129 to malloced memory stay within their bounds. 130 * No support for compaction. 131 132* Synopsis of compile-time options: 133 134 People have reported using previous versions of this malloc on all 135 versions of Unix, sometimes by tweaking some of the defines 136 below. It has been tested most extensively on Solaris and 137 Linux. It is also reported to work on WIN32 platforms. 138 People have also reported adapting this malloc for use in 139 stand-alone embedded systems. 140 141 The implementation is in straight, hand-tuned ANSI C. Among other 142 consequences, it uses a lot of macros. Because of this, to be at 143 all usable, this code should be compiled using an optimizing compiler 144 (for example gcc -O2) that can simplify expressions and control 145 paths. 146 147 __STD_C (default: derived from C compiler defines) 148 Nonzero if using ANSI-standard C compiler, a C++ compiler, or 149 a C compiler sufficiently close to ANSI to get away with it. 150 DEBUG (default: NOT defined) 151 Define to enable debugging. Adds fairly extensive assertion-based 152 checking to help track down memory errors, but noticeably slows down 153 execution. 154 REALLOC_ZERO_BYTES_FREES (default: NOT defined) 155 Define this if you think that realloc(p, 0) should be equivalent 156 to free(p). Otherwise, since malloc returns a unique pointer for 157 malloc(0), so does realloc(p, 0). 158 HAVE_MEMCPY (default: defined) 159 Define if you are not otherwise using ANSI STD C, but still 160 have memcpy and memset in your C library and want to use them. 161 Otherwise, simple internal versions are supplied. 162 USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise) 163 Define as 1 if you want the C library versions of memset and 164 memcpy called in realloc and calloc (otherwise macro versions are used). 165 At least on some platforms, the simple macro versions usually 166 outperform libc versions. 167 HAVE_MMAP (default: defined as 1) 168 Define to non-zero to optionally make malloc() use mmap() to 169 allocate very large blocks. 170 HAVE_MREMAP (default: defined as 0 unless Linux libc set) 171 Define to non-zero to optionally make realloc() use mremap() to 172 reallocate very large blocks. 173 malloc_getpagesize (default: derived from system #includes) 174 Either a constant or routine call returning the system page size. 175 HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined) 176 Optionally define if you are on a system with a /usr/include/malloc.h 177 that declares struct mallinfo. It is not at all necessary to 178 define this even if you do, but will ensure consistency. 179 INTERNAL_SIZE_T (default: size_t) 180 Define to a 32-bit type (probably `unsigned int') if you are on a 181 64-bit machine, yet do not want or need to allow malloc requests of 182 greater than 2^31 to be handled. This saves space, especially for 183 very small chunks. 184 INTERNAL_LINUX_C_LIB (default: NOT defined) 185 Defined only when compiled as part of Linux libc. 186 Also note that there is some odd internal name-mangling via defines 187 (for example, internally, `malloc' is named `mALLOc') needed 188 when compiling in this case. These look funny but don't otherwise 189 affect anything. 190 WIN32 (default: undefined) 191 Define this on MS win (95, nt) platforms to compile in sbrk emulation. 192 LACKS_UNISTD_H (default: undefined if not WIN32) 193 Define this if your system does not have a <unistd.h>. 194 LACKS_SYS_PARAM_H (default: undefined if not WIN32) 195 Define this if your system does not have a <sys/param.h>. 196 MORECORE (default: sbrk) 197 The name of the routine to call to obtain more memory from the system. 198 MORECORE_FAILURE (default: -1) 199 The value returned upon failure of MORECORE. 200 MORECORE_CLEARS (default 1) 201 True (1) if the routine mapped to MORECORE zeroes out memory (which 202 holds for sbrk). 203 DEFAULT_TRIM_THRESHOLD 204 DEFAULT_TOP_PAD 205 DEFAULT_MMAP_THRESHOLD 206 DEFAULT_MMAP_MAX 207 Default values of tunable parameters (described in detail below) 208 controlling interaction with host system routines (sbrk, mmap, etc). 209 These values may also be changed dynamically via mallopt(). The 210 preset defaults are those that give best performance for typical 211 programs/systems. 212 USE_DL_PREFIX (default: undefined) 213 Prefix all public routines with the string 'dl'. Useful to 214 quickly avoid procedure declaration conflicts and linker symbol 215 conflicts with existing memory allocation routines. 216 217 218*/ 219 220 221 222 223/* Preliminaries */ 224 225#ifndef __STD_C 226#ifdef __STDC__ 227#define __STD_C 1 228#else 229#if __cplusplus 230#define __STD_C 1 231#else 232#define __STD_C 0 233#endif /*__cplusplus*/ 234#endif /*__STDC__*/ 235#endif /*__STD_C*/ 236 237#ifndef Void_t 238#if (__STD_C || defined(WIN32)) 239#define Void_t void 240#else 241#define Void_t char 242#endif 243#endif /*Void_t*/ 244 245#if __STD_C 246#include <stddef.h> /* for size_t */ 247#else 248#include <sys/types.h> 249#endif 250 251#ifdef __cplusplus 252extern "C" { 253#endif 254 255#include <stdio.h> /* needed for malloc_stats */ 256 257 258/* 259 Compile-time options 260*/ 261 262 263/* 264 Debugging: 265 266 Because freed chunks may be overwritten with link fields, this 267 malloc will often die when freed memory is overwritten by user 268 programs. This can be very effective (albeit in an annoying way) 269 in helping track down dangling pointers. 270 271 If you compile with -DDEBUG, a number of assertion checks are 272 enabled that will catch more memory errors. You probably won't be 273 able to make much sense of the actual assertion errors, but they 274 should help you locate incorrectly overwritten memory. The 275 checking is fairly extensive, and will slow down execution 276 noticeably. Calling malloc_stats or mallinfo with DEBUG set will 277 attempt to check every non-mmapped allocated and free chunk in the 278 course of computing the summmaries. (By nature, mmapped regions 279 cannot be checked very much automatically.) 280 281 Setting DEBUG may also be helpful if you are trying to modify 282 this code. The assertions in the check routines spell out in more 283 detail the assumptions and invariants underlying the algorithms. 284 285*/ 286 287#if DEBUG 288#include <assert.h> 289#else 290#define assert(x) ((void)0) 291#endif 292 293 294/* 295 INTERNAL_SIZE_T is the word-size used for internal bookkeeping 296 of chunk sizes. On a 64-bit machine, you can reduce malloc 297 overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int' 298 at the expense of not being able to handle requests greater than 299 2^31. This limitation is hardly ever a concern; you are encouraged 300 to set this. However, the default version is the same as size_t. 301*/ 302 303#ifndef INTERNAL_SIZE_T 304#define INTERNAL_SIZE_T size_t 305#endif 306 307/* 308 REALLOC_ZERO_BYTES_FREES should be set if a call to 309 realloc with zero bytes should be the same as a call to free. 310 Some people think it should. Otherwise, since this malloc 311 returns a unique pointer for malloc(0), so does realloc(p, 0). 312*/ 313 314 315/* #define REALLOC_ZERO_BYTES_FREES */ 316 317 318/* 319 WIN32 causes an emulation of sbrk to be compiled in 320 mmap-based options are not currently supported in WIN32. 321*/ 322 323/* #define WIN32 */ 324#ifdef WIN32 325#define MORECORE wsbrk 326#define HAVE_MMAP 0 327 328#define LACKS_UNISTD_H 329#define LACKS_SYS_PARAM_H 330 331/* 332 Include 'windows.h' to get the necessary declarations for the 333 Microsoft Visual C++ data structures and routines used in the 'sbrk' 334 emulation. 335 336 Define WIN32_LEAN_AND_MEAN so that only the essential Microsoft 337 Visual C++ header files are included. 338*/ 339#define WIN32_LEAN_AND_MEAN 340#include <windows.h> 341#endif 342 343 344/* 345 HAVE_MEMCPY should be defined if you are not otherwise using 346 ANSI STD C, but still have memcpy and memset in your C library 347 and want to use them in calloc and realloc. Otherwise simple 348 macro versions are defined here. 349 350 USE_MEMCPY should be defined as 1 if you actually want to 351 have memset and memcpy called. People report that the macro 352 versions are often enough faster than libc versions on many 353 systems that it is better to use them. 354 355*/ 356 357#define HAVE_MEMCPY 358 359#ifndef USE_MEMCPY 360#ifdef HAVE_MEMCPY 361#define USE_MEMCPY 1 362#else 363#define USE_MEMCPY 0 364#endif 365#endif 366 367#if (__STD_C || defined(HAVE_MEMCPY)) 368 369#if __STD_C 370void* memset(void*, int, size_t); 371void* memcpy(void*, const void*, size_t); 372#else 373#ifdef WIN32 374// On Win32 platforms, 'memset()' and 'memcpy()' are already declared in 375// 'windows.h' 376#else 377Void_t* memset(); 378Void_t* memcpy(); 379#endif 380#endif 381#endif 382 383#if USE_MEMCPY 384 385/* The following macros are only invoked with (2n+1)-multiples of 386 INTERNAL_SIZE_T units, with a positive integer n. This is exploited 387 for fast inline execution when n is small. */ 388 389#define MALLOC_ZERO(charp, nbytes) \ 390do { \ 391 INTERNAL_SIZE_T mzsz = (nbytes); \ 392 if(mzsz <= 9*sizeof(mzsz)) { \ 393 INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \ 394 if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \ 395 *mz++ = 0; \ 396 if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \ 397 *mz++ = 0; \ 398 if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \ 399 *mz++ = 0; }}} \ 400 *mz++ = 0; \ 401 *mz++ = 0; \ 402 *mz = 0; \ 403 } else memset((charp), 0, mzsz); \ 404} while(0) 405 406#define MALLOC_COPY(dest,src,nbytes) \ 407do { \ 408 INTERNAL_SIZE_T mcsz = (nbytes); \ 409 if(mcsz <= 9*sizeof(mcsz)) { \ 410 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \ 411 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \ 412 if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ 413 *mcdst++ = *mcsrc++; \ 414 if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ 415 *mcdst++ = *mcsrc++; \ 416 if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ 417 *mcdst++ = *mcsrc++; }}} \ 418 *mcdst++ = *mcsrc++; \ 419 *mcdst++ = *mcsrc++; \ 420 *mcdst = *mcsrc ; \ 421 } else memcpy(dest, src, mcsz); \ 422} while(0) 423 424#else /* !USE_MEMCPY */ 425 426/* Use Duff's device for good zeroing/copying performance. */ 427 428#define MALLOC_ZERO(charp, nbytes) \ 429do { \ 430 INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \ 431 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \ 432 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \ 433 switch (mctmp) { \ 434 case 0: for(;;) { *mzp++ = 0; \ 435 case 7: *mzp++ = 0; \ 436 case 6: *mzp++ = 0; \ 437 case 5: *mzp++ = 0; \ 438 case 4: *mzp++ = 0; \ 439 case 3: *mzp++ = 0; \ 440 case 2: *mzp++ = 0; \ 441 case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \ 442 } \ 443} while(0) 444 445#define MALLOC_COPY(dest,src,nbytes) \ 446do { \ 447 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \ 448 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \ 449 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \ 450 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \ 451 switch (mctmp) { \ 452 case 0: for(;;) { *mcdst++ = *mcsrc++; \ 453 case 7: *mcdst++ = *mcsrc++; \ 454 case 6: *mcdst++ = *mcsrc++; \ 455 case 5: *mcdst++ = *mcsrc++; \ 456 case 4: *mcdst++ = *mcsrc++; \ 457 case 3: *mcdst++ = *mcsrc++; \ 458 case 2: *mcdst++ = *mcsrc++; \ 459 case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \ 460 } \ 461} while(0) 462 463#endif 464 465 466/* 467 Define HAVE_MMAP to optionally make malloc() use mmap() to 468 allocate very large blocks. These will be returned to the 469 operating system immediately after a free(). 470*/ 471 472#ifndef HAVE_MMAP 473#define HAVE_MMAP 1 474#endif 475 476/* 477 Define HAVE_MREMAP to make realloc() use mremap() to re-allocate 478 large blocks. This is currently only possible on Linux with 479 kernel versions newer than 1.3.77. 480*/ 481 482#ifndef HAVE_MREMAP 483#ifdef INTERNAL_LINUX_C_LIB 484#define HAVE_MREMAP 1 485#else 486#define HAVE_MREMAP 0 487#endif 488#endif 489 490#if HAVE_MMAP 491 492#include <unistd.h> 493#include <fcntl.h> 494#include <sys/mman.h> 495 496#if !defined(MAP_ANONYMOUS) && defined(MAP_ANON) 497#define MAP_ANONYMOUS MAP_ANON 498#endif 499 500#endif /* HAVE_MMAP */ 501 502/* 503 Access to system page size. To the extent possible, this malloc 504 manages memory from the system in page-size units. 505 506 The following mechanics for getpagesize were adapted from 507 bsd/gnu getpagesize.h 508*/ 509 510#ifndef LACKS_UNISTD_H 511# include <unistd.h> 512#endif 513 514#ifndef malloc_getpagesize 515# ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */ 516# ifndef _SC_PAGE_SIZE 517# define _SC_PAGE_SIZE _SC_PAGESIZE 518# endif 519# endif 520# ifdef _SC_PAGE_SIZE 521# define malloc_getpagesize sysconf(_SC_PAGE_SIZE) 522# else 523# if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE) 524 extern size_t getpagesize(); 525# define malloc_getpagesize getpagesize() 526# else 527# ifdef WIN32 528# define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */ 529# else 530# ifndef LACKS_SYS_PARAM_H 531# include <sys/param.h> 532# endif 533# ifdef EXEC_PAGESIZE 534# define malloc_getpagesize EXEC_PAGESIZE 535# else 536# ifdef NBPG 537# ifndef CLSIZE 538# define malloc_getpagesize NBPG 539# else 540# define malloc_getpagesize (NBPG * CLSIZE) 541# endif 542# else 543# ifdef NBPC 544# define malloc_getpagesize NBPC 545# else 546# ifdef PAGESIZE 547# define malloc_getpagesize PAGESIZE 548# else 549# define malloc_getpagesize (4096) /* just guess */ 550# endif 551# endif 552# endif 553# endif 554# endif 555# endif 556# endif 557#endif 558 559 560 561/* 562 563 This version of malloc supports the standard SVID/XPG mallinfo 564 routine that returns a struct containing the same kind of 565 information you can get from malloc_stats. It should work on 566 any SVID/XPG compliant system that has a /usr/include/malloc.h 567 defining struct mallinfo. (If you'd like to install such a thing 568 yourself, cut out the preliminary declarations as described above 569 and below and save them in a malloc.h file. But there's no 570 compelling reason to bother to do this.) 571 572 The main declaration needed is the mallinfo struct that is returned 573 (by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a 574 bunch of fields, most of which are not even meaningful in this 575 version of malloc. Some of these fields are are instead filled by 576 mallinfo() with other numbers that might possibly be of interest. 577 578 HAVE_USR_INCLUDE_MALLOC_H should be set if you have a 579 /usr/include/malloc.h file that includes a declaration of struct 580 mallinfo. If so, it is included; else an SVID2/XPG2 compliant 581 version is declared below. These must be precisely the same for 582 mallinfo() to work. 583 584*/ 585 586/* #define HAVE_USR_INCLUDE_MALLOC_H */ 587 588#if HAVE_USR_INCLUDE_MALLOC_H 589#include "/usr/include/malloc.h" 590#else 591 592/* SVID2/XPG mallinfo structure */ 593 594struct mallinfo { 595 int arena; /* total space allocated from system */ 596 int ordblks; /* number of non-inuse chunks */ 597 int smblks; /* unused -- always zero */ 598 int hblks; /* number of mmapped regions */ 599 int hblkhd; /* total space in mmapped regions */ 600 int usmblks; /* unused -- always zero */ 601 int fsmblks; /* unused -- always zero */ 602 int uordblks; /* total allocated space */ 603 int fordblks; /* total non-inuse space */ 604 int keepcost; /* top-most, releasable (via malloc_trim) space */ 605}; 606 607/* SVID2/XPG mallopt options */ 608 609#define M_MXFAST 1 /* UNUSED in this malloc */ 610#define M_NLBLKS 2 /* UNUSED in this malloc */ 611#define M_GRAIN 3 /* UNUSED in this malloc */ 612#define M_KEEP 4 /* UNUSED in this malloc */ 613 614#endif 615 616/* mallopt options that actually do something */ 617 618#define M_TRIM_THRESHOLD -1 619#define M_TOP_PAD -2 620#define M_MMAP_THRESHOLD -3 621#define M_MMAP_MAX -4 622 623 624 625#ifndef DEFAULT_TRIM_THRESHOLD 626#define DEFAULT_TRIM_THRESHOLD (128 * 1024) 627#endif 628 629/* 630 M_TRIM_THRESHOLD is the maximum amount of unused top-most memory 631 to keep before releasing via malloc_trim in free(). 632 633 Automatic trimming is mainly useful in long-lived programs. 634 Because trimming via sbrk can be slow on some systems, and can 635 sometimes be wasteful (in cases where programs immediately 636 afterward allocate more large chunks) the value should be high 637 enough so that your overall system performance would improve by 638 releasing. 639 640 The trim threshold and the mmap control parameters (see below) 641 can be traded off with one another. Trimming and mmapping are 642 two different ways of releasing unused memory back to the 643 system. Between these two, it is often possible to keep 644 system-level demands of a long-lived program down to a bare 645 minimum. For example, in one test suite of sessions measuring 646 the XF86 X server on Linux, using a trim threshold of 128K and a 647 mmap threshold of 192K led to near-minimal long term resource 648 consumption. 649 650 If you are using this malloc in a long-lived program, it should 651 pay to experiment with these values. As a rough guide, you 652 might set to a value close to the average size of a process 653 (program) running on your system. Releasing this much memory 654 would allow such a process to run in memory. Generally, it's 655 worth it to tune for trimming rather tham memory mapping when a 656 program undergoes phases where several large chunks are 657 allocated and released in ways that can reuse each other's 658 storage, perhaps mixed with phases where there are no such 659 chunks at all. And in well-behaved long-lived programs, 660 controlling release of large blocks via trimming versus mapping 661 is usually faster. 662 663 However, in most programs, these parameters serve mainly as 664 protection against the system-level effects of carrying around 665 massive amounts of unneeded memory. Since frequent calls to 666 sbrk, mmap, and munmap otherwise degrade performance, the default 667 parameters are set to relatively high values that serve only as 668 safeguards. 669 670 The default trim value is high enough to cause trimming only in 671 fairly extreme (by current memory consumption standards) cases. 672 It must be greater than page size to have any useful effect. To 673 disable trimming completely, you can set to (unsigned long)(-1); 674 675 676*/ 677 678 679#ifndef DEFAULT_TOP_PAD 680#define DEFAULT_TOP_PAD (0) 681#endif 682 683/* 684 M_TOP_PAD is the amount of extra `padding' space to allocate or 685 retain whenever sbrk is called. It is used in two ways internally: 686 687 * When sbrk is called to extend the top of the arena to satisfy 688 a new malloc request, this much padding is added to the sbrk 689 request. 690 691 * When malloc_trim is called automatically from free(), 692 it is used as the `pad' argument. 693 694 In both cases, the actual amount of padding is rounded 695 so that the end of the arena is always a system page boundary. 696 697 The main reason for using padding is to avoid calling sbrk so 698 often. Having even a small pad greatly reduces the likelihood 699 that nearly every malloc request during program start-up (or 700 after trimming) will invoke sbrk, which needlessly wastes 701 time. 702 703 Automatic rounding-up to page-size units is normally sufficient 704 to avoid measurable overhead, so the default is 0. However, in 705 systems where sbrk is relatively slow, it can pay to increase 706 this value, at the expense of carrying around more memory than 707 the program needs. 708 709*/ 710 711 712#ifndef DEFAULT_MMAP_THRESHOLD 713#define DEFAULT_MMAP_THRESHOLD (128 * 1024) 714#endif 715 716/* 717 718 M_MMAP_THRESHOLD is the request size threshold for using mmap() 719 to service a request. Requests of at least this size that cannot 720 be allocated using already-existing space will be serviced via mmap. 721 (If enough normal freed space already exists it is used instead.) 722 723 Using mmap segregates relatively large chunks of memory so that 724 they can be individually obtained and released from the host 725 system. A request serviced through mmap is never reused by any 726 other request (at least not directly; the system may just so 727 happen to remap successive requests to the same locations). 728 729 Segregating space in this way has the benefit that mmapped space 730 can ALWAYS be individually released back to the system, which 731 helps keep the system level memory demands of a long-lived 732 program low. Mapped memory can never become `locked' between 733 other chunks, as can happen with normally allocated chunks, which 734 menas that even trimming via malloc_trim would not release them. 735 736 However, it has the disadvantages that: 737 738 1. The space cannot be reclaimed, consolidated, and then 739 used to service later requests, as happens with normal chunks. 740 2. It can lead to more wastage because of mmap page alignment 741 requirements 742 3. It causes malloc performance to be more dependent on host 743 system memory management support routines which may vary in 744 implementation quality and may impose arbitrary 745 limitations. Generally, servicing a request via normal 746 malloc steps is faster than going through a system's mmap. 747 748 All together, these considerations should lead you to use mmap 749 only for relatively large requests. 750 751 752*/ 753 754 755 756#ifndef DEFAULT_MMAP_MAX 757#if HAVE_MMAP 758#define DEFAULT_MMAP_MAX (64) 759#else 760#define DEFAULT_MMAP_MAX (0) 761#endif 762#endif 763 764/* 765 M_MMAP_MAX is the maximum number of requests to simultaneously 766 service using mmap. This parameter exists because: 767 768 1. Some systems have a limited number of internal tables for 769 use by mmap. 770 2. In most systems, overreliance on mmap can degrade overall 771 performance. 772 3. If a program allocates many large regions, it is probably 773 better off using normal sbrk-based allocation routines that 774 can reclaim and reallocate normal heap memory. Using a 775 small value allows transition into this mode after the 776 first few allocations. 777 778 Setting to 0 disables all use of mmap. If HAVE_MMAP is not set, 779 the default value is 0, and attempts to set it to non-zero values 780 in mallopt will fail. 781*/ 782 783 784 785 786/* 787 USE_DL_PREFIX will prefix all public routines with the string 'dl'. 788 Useful to quickly avoid procedure declaration conflicts and linker 789 symbol conflicts with existing memory allocation routines. 790 791*/ 792 793/* #define USE_DL_PREFIX */ 794 795 796 797 798/* 799 800 Special defines for linux libc 801 802 Except when compiled using these special defines for Linux libc 803 using weak aliases, this malloc is NOT designed to work in 804 multithreaded applications. No semaphores or other concurrency 805 control are provided to ensure that multiple malloc or free calls 806 don't run at the same time, which could be disasterous. A single 807 semaphore could be used across malloc, realloc, and free (which is 808 essentially the effect of the linux weak alias approach). It would 809 be hard to obtain finer granularity. 810 811*/ 812 813 814#ifdef INTERNAL_LINUX_C_LIB 815 816#if __STD_C 817 818Void_t * __default_morecore_init (ptrdiff_t); 819Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init; 820 821#else 822 823Void_t * __default_morecore_init (); 824Void_t *(*__morecore)() = __default_morecore_init; 825 826#endif 827 828#define MORECORE (*__morecore) 829#define MORECORE_FAILURE 0 830#define MORECORE_CLEARS 1 831 832#else /* INTERNAL_LINUX_C_LIB */ 833 834#if __STD_C 835extern Void_t* sbrk(ptrdiff_t); 836#else 837extern Void_t* sbrk(); 838#endif 839 840#ifndef MORECORE 841#define MORECORE sbrk 842#endif 843 844#ifndef MORECORE_FAILURE 845#define MORECORE_FAILURE -1 846#endif 847 848#ifndef MORECORE_CLEARS 849#define MORECORE_CLEARS 1 850#endif 851 852#endif /* INTERNAL_LINUX_C_LIB */ 853 854#if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__) 855 856#define cALLOc __libc_calloc 857#define fREe __libc_free 858#define mALLOc __libc_malloc 859#define mEMALIGn __libc_memalign 860#define rEALLOc __libc_realloc 861#define vALLOc __libc_valloc 862#define pvALLOc __libc_pvalloc 863#define mALLINFo __libc_mallinfo 864#define mALLOPt __libc_mallopt 865 866#pragma weak calloc = __libc_calloc 867#pragma weak free = __libc_free 868#pragma weak cfree = __libc_free 869#pragma weak malloc = __libc_malloc 870#pragma weak memalign = __libc_memalign 871#pragma weak realloc = __libc_realloc 872#pragma weak valloc = __libc_valloc 873#pragma weak pvalloc = __libc_pvalloc 874#pragma weak mallinfo = __libc_mallinfo 875#pragma weak mallopt = __libc_mallopt 876 877#else 878 879#ifdef USE_DL_PREFIX 880#define cALLOc dlcalloc 881#define fREe dlfree 882#define mALLOc dlmalloc 883#define mEMALIGn dlmemalign 884#define rEALLOc dlrealloc 885#define vALLOc dlvalloc 886#define pvALLOc dlpvalloc 887#define mALLINFo dlmallinfo 888#define mALLOPt dlmallopt 889#else /* USE_DL_PREFIX */ 890#define cALLOc calloc 891#define fREe free 892#define mALLOc malloc 893#define mEMALIGn memalign 894#define rEALLOc realloc 895#define vALLOc valloc 896#define pvALLOc pvalloc 897#define mALLINFo mallinfo 898#define mALLOPt mallopt 899#endif /* USE_DL_PREFIX */ 900 901#endif 902 903/* Public routines */ 904 905#if __STD_C 906 907Void_t* mALLOc(size_t); 908void fREe(Void_t*); 909Void_t* rEALLOc(Void_t*, size_t); 910Void_t* mEMALIGn(size_t, size_t); 911Void_t* vALLOc(size_t); 912Void_t* pvALLOc(size_t); 913Void_t* cALLOc(size_t, size_t); 914void cfree(Void_t*); 915int malloc_trim(size_t); 916size_t malloc_usable_size(Void_t*); 917void malloc_stats(); 918int mALLOPt(int, int); 919struct mallinfo mALLINFo(void); 920#else 921Void_t* mALLOc(); 922void fREe(); 923Void_t* rEALLOc(); 924Void_t* mEMALIGn(); 925Void_t* vALLOc(); 926Void_t* pvALLOc(); 927Void_t* cALLOc(); 928void cfree(); 929int malloc_trim(); 930size_t malloc_usable_size(); 931void malloc_stats(); 932int mALLOPt(); 933struct mallinfo mALLINFo(); 934#endif 935 936 937#ifdef __cplusplus 938}; /* end of extern "C" */ 939#endif 940 941/* ---------- To make a malloc.h, end cutting here ------------ */ 942 943 944/* 945 Emulation of sbrk for WIN32 946 All code within the ifdef WIN32 is untested by me. 947 948 Thanks to Martin Fong and others for supplying this. 949*/ 950 951 952#ifdef WIN32 953 954#define AlignPage(add) (((add) + (malloc_getpagesize-1)) & \ 955~(malloc_getpagesize-1)) 956#define AlignPage64K(add) (((add) + (0x10000 - 1)) & ~(0x10000 - 1)) 957 958/* resrve 64MB to insure large contiguous space */ 959#define RESERVED_SIZE (1024*1024*64) 960#define NEXT_SIZE (2048*1024) 961#define TOP_MEMORY ((unsigned long)2*1024*1024*1024) 962 963struct GmListElement; 964typedef struct GmListElement GmListElement; 965 966struct GmListElement 967{ 968 GmListElement* next; 969 void* base; 970}; 971 972static GmListElement* head = 0; 973static unsigned int gNextAddress = 0; 974static unsigned int gAddressBase = 0; 975static unsigned int gAllocatedSize = 0; 976 977static 978GmListElement* makeGmListElement (void* bas) 979{ 980 GmListElement* this; 981 this = (GmListElement*)(void*)LocalAlloc (0, sizeof (GmListElement)); 982 assert (this); 983 if (this) 984 { 985 this->base = bas; 986 this->next = head; 987 head = this; 988 } 989 return this; 990} 991 992void gcleanup () 993{ 994 BOOL rval; 995 assert ( (head == NULL) || (head->base == (void*)gAddressBase)); 996 if (gAddressBase && (gNextAddress - gAddressBase)) 997 { 998 rval = VirtualFree ((void*)gAddressBase, 999 gNextAddress - gAddressBase, 1000 MEM_DECOMMIT); 1001 assert (rval); 1002 } 1003 while (head) 1004 { 1005 GmListElement* next = head->next; 1006 rval = VirtualFree (head->base, 0, MEM_RELEASE); 1007 assert (rval); 1008 LocalFree (head); 1009 head = next; 1010 } 1011} 1012 1013static 1014void* findRegion (void* start_address, unsigned long size) 1015{ 1016 MEMORY_BASIC_INFORMATION info; 1017 if (size >= TOP_MEMORY) return NULL; 1018 1019 while ((unsigned long)start_address + size < TOP_MEMORY) 1020 { 1021 VirtualQuery (start_address, &info, sizeof (info)); 1022 if ((info.State == MEM_FREE) && (info.RegionSize >= size)) 1023 return start_address; 1024 else 1025 { 1026 // Requested region is not available so see if the 1027 // next region is available. Set 'start_address' 1028 // to the next region and call 'VirtualQuery()' 1029 // again. 1030 1031 start_address = (char*)info.BaseAddress + info.RegionSize; 1032 1033 // Make sure we start looking for the next region 1034 // on the *next* 64K boundary. Otherwise, even if 1035 // the new region is free according to 1036 // 'VirtualQuery()', the subsequent call to 1037 // 'VirtualAlloc()' (which follows the call to 1038 // this routine in 'wsbrk()') will round *down* 1039 // the requested address to a 64K boundary which 1040 // we already know is an address in the 1041 // unavailable region. Thus, the subsequent call 1042 // to 'VirtualAlloc()' will fail and bring us back 1043 // here, causing us to go into an infinite loop. 1044 1045 start_address = 1046 (void *) AlignPage64K((unsigned long) start_address); 1047 } 1048 } 1049 return NULL; 1050 1051} 1052 1053 1054void* wsbrk (long size) 1055{ 1056 void* tmp; 1057 if (size > 0) 1058 { 1059 if (gAddressBase == 0) 1060 { 1061 gAllocatedSize = max (RESERVED_SIZE, AlignPage (size)); 1062 gNextAddress = gAddressBase = 1063 (unsigned int)VirtualAlloc (NULL, gAllocatedSize, 1064 MEM_RESERVE, PAGE_NOACCESS); 1065 } else if (AlignPage (gNextAddress + size) > (gAddressBase + 1066gAllocatedSize)) 1067 { 1068 long new_size = max (NEXT_SIZE, AlignPage (size)); 1069 void* new_address = (void*)(gAddressBase+gAllocatedSize); 1070 do 1071 { 1072 new_address = findRegion (new_address, new_size); 1073 1074 if (new_address == 0) 1075 return (void*)-1; 1076 1077 gAddressBase = gNextAddress = 1078 (unsigned int)VirtualAlloc (new_address, new_size, 1079 MEM_RESERVE, PAGE_NOACCESS); 1080 // repeat in case of race condition 1081 // The region that we found has been snagged 1082 // by another thread 1083 } 1084 while (gAddressBase == 0); 1085 1086 assert (new_address == (void*)gAddressBase); 1087 1088 gAllocatedSize = new_size; 1089 1090 if (!makeGmListElement ((void*)gAddressBase)) 1091 return (void*)-1; 1092 } 1093 if ((size + gNextAddress) > AlignPage (gNextAddress)) 1094 { 1095 void* res; 1096 res = VirtualAlloc ((void*)AlignPage (gNextAddress), 1097 (size + gNextAddress - 1098 AlignPage (gNextAddress)), 1099 MEM_COMMIT, PAGE_READWRITE); 1100 if (res == 0) 1101 return (void*)-1; 1102 } 1103 tmp = (void*)gNextAddress; 1104 gNextAddress = (unsigned int)tmp + size; 1105 return tmp; 1106 } 1107 else if (size < 0) 1108 { 1109 unsigned int alignedGoal = AlignPage (gNextAddress + size); 1110 /* Trim by releasing the virtual memory */ 1111 if (alignedGoal >= gAddressBase) 1112 { 1113 VirtualFree ((void*)alignedGoal, gNextAddress - alignedGoal, 1114 MEM_DECOMMIT); 1115 gNextAddress = gNextAddress + size; 1116 return (void*)gNextAddress; 1117 } 1118 else 1119 { 1120 VirtualFree ((void*)gAddressBase, gNextAddress - gAddressBase, 1121 MEM_DECOMMIT); 1122 gNextAddress = gAddressBase; 1123 return (void*)-1; 1124 } 1125 } 1126 else 1127 { 1128 return (void*)gNextAddress; 1129 } 1130} 1131 1132#endif 1133 1134 1135 1136/* 1137 Type declarations 1138*/ 1139 1140 1141struct malloc_chunk 1142{ 1143 INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */ 1144 INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */ 1145 struct malloc_chunk* fd; /* double links -- used only if free. */ 1146 struct malloc_chunk* bk; 1147}; 1148 1149typedef struct malloc_chunk* mchunkptr; 1150 1151/* 1152 1153 malloc_chunk details: 1154 1155 (The following includes lightly edited explanations by Colin Plumb.) 1156 1157 Chunks of memory are maintained using a `boundary tag' method as 1158 described in e.g., Knuth or Standish. (See the paper by Paul 1159 Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a 1160 survey of such techniques.) Sizes of free chunks are stored both 1161 in the front of each chunk and at the end. This makes 1162 consolidating fragmented chunks into bigger chunks very fast. The 1163 size fields also hold bits representing whether chunks are free or 1164 in use. 1165 1166 An allocated chunk looks like this: 1167 1168 1169 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1170 | Size of previous chunk, if allocated | | 1171 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1172 | Size of chunk, in bytes |P| 1173 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1174 | User data starts here... . 1175 . . 1176 . (malloc_usable_space() bytes) . 1177 . | 1178nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1179 | Size of chunk | 1180 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1181 1182 1183 Where "chunk" is the front of the chunk for the purpose of most of 1184 the malloc code, but "mem" is the pointer that is returned to the 1185 user. "Nextchunk" is the beginning of the next contiguous chunk. 1186 1187 Chunks always begin on even word boundries, so the mem portion 1188 (which is returned to the user) is also on an even word boundary, and 1189 thus double-word aligned. 1190 1191 Free chunks are stored in circular doubly-linked lists, and look like this: 1192 1193 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1194 | Size of previous chunk | 1195 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1196 `head:' | Size of chunk, in bytes |P| 1197 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1198 | Forward pointer to next chunk in list | 1199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1200 | Back pointer to previous chunk in list | 1201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1202 | Unused space (may be 0 bytes long) . 1203 . . 1204 . | 1205nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1206 `foot:' | Size of chunk, in bytes | 1207 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1208 1209 The P (PREV_INUSE) bit, stored in the unused low-order bit of the 1210 chunk size (which is always a multiple of two words), is an in-use 1211 bit for the *previous* chunk. If that bit is *clear*, then the 1212 word before the current chunk size contains the previous chunk 1213 size, and can be used to find the front of the previous chunk. 1214 (The very first chunk allocated always has this bit set, 1215 preventing access to non-existent (or non-owned) memory.) 1216 1217 Note that the `foot' of the current chunk is actually represented 1218 as the prev_size of the NEXT chunk. (This makes it easier to 1219 deal with alignments etc). 1220 1221 The two exceptions to all this are 1222 1223 1. The special chunk `top', which doesn't bother using the 1224 trailing size field since there is no 1225 next contiguous chunk that would have to index off it. (After 1226 initialization, `top' is forced to always exist. If it would 1227 become less than MINSIZE bytes long, it is replenished via 1228 malloc_extend_top.) 1229 1230 2. Chunks allocated via mmap, which have the second-lowest-order 1231 bit (IS_MMAPPED) set in their size fields. Because they are 1232 never merged or traversed from any other chunk, they have no 1233 foot size or inuse information. 1234 1235 Available chunks are kept in any of several places (all declared below): 1236 1237 * `av': An array of chunks serving as bin headers for consolidated 1238 chunks. Each bin is doubly linked. The bins are approximately 1239 proportionally (log) spaced. There are a lot of these bins 1240 (128). This may look excessive, but works very well in 1241 practice. All procedures maintain the invariant that no 1242 consolidated chunk physically borders another one. Chunks in 1243 bins are kept in size order, with ties going to the 1244 approximately least recently used chunk. 1245 1246 The chunks in each bin are maintained in decreasing sorted order by 1247 size. This is irrelevant for the small bins, which all contain 1248 the same-sized chunks, but facilitates best-fit allocation for 1249 larger chunks. (These lists are just sequential. Keeping them in 1250 order almost never requires enough traversal to warrant using 1251 fancier ordered data structures.) Chunks of the same size are 1252 linked with the most recently freed at the front, and allocations 1253 are taken from the back. This results in LRU or FIFO allocation 1254 order, which tends to give each chunk an equal opportunity to be 1255 consolidated with adjacent freed chunks, resulting in larger free 1256 chunks and less fragmentation. 1257 1258 * `top': The top-most available chunk (i.e., the one bordering the 1259 end of available memory) is treated specially. It is never 1260 included in any bin, is used only if no other chunk is 1261 available, and is released back to the system if it is very 1262 large (see M_TRIM_THRESHOLD). 1263 1264 * `last_remainder': A bin holding only the remainder of the 1265 most recently split (non-top) chunk. This bin is checked 1266 before other non-fitting chunks, so as to provide better 1267 locality for runs of sequentially allocated chunks. 1268 1269 * Implicitly, through the host system's memory mapping tables. 1270 If supported, requests greater than a threshold are usually 1271 serviced via calls to mmap, and then later released via munmap. 1272 1273*/ 1274 1275 1276 1277 1278 1279 1280/* sizes, alignments */ 1281 1282#define SIZE_SZ (sizeof(INTERNAL_SIZE_T)) 1283#define MALLOC_ALIGNMENT (SIZE_SZ + SIZE_SZ) 1284#define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1) 1285#define MINSIZE (sizeof(struct malloc_chunk)) 1286 1287/* conversion from malloc headers to user pointers, and back */ 1288 1289#define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ)) 1290#define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ)) 1291 1292/* pad request bytes into a usable size */ 1293 1294#define request2size(req) \ 1295 (((long)((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \ 1296 (long)(MINSIZE + MALLOC_ALIGN_MASK)) ? MINSIZE : \ 1297 (((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) & ~(MALLOC_ALIGN_MASK))) 1298 1299/* Check if m has acceptable alignment */ 1300 1301#define aligned_OK(m) (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0) 1302 1303 1304 1305 1306/* 1307 Physical chunk operations 1308*/ 1309 1310 1311/* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */ 1312 1313#define PREV_INUSE 0x1 1314 1315/* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */ 1316 1317#define IS_MMAPPED 0x2 1318 1319/* Bits to mask off when extracting size */ 1320 1321#define SIZE_BITS (PREV_INUSE|IS_MMAPPED) 1322 1323 1324/* Ptr to next physical malloc_chunk. */ 1325 1326#define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) )) 1327 1328/* Ptr to previous physical malloc_chunk */ 1329 1330#define prev_chunk(p)\ 1331 ((mchunkptr)( ((char*)(p)) - ((p)->prev_size) )) 1332 1333 1334/* Treat space at ptr + offset as a chunk */ 1335 1336#define chunk_at_offset(p, s) ((mchunkptr)(((char*)(p)) + (s))) 1337 1338 1339 1340 1341/* 1342 Dealing with use bits 1343*/ 1344 1345/* extract p's inuse bit */ 1346 1347#define inuse(p)\ 1348((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE) 1349 1350/* extract inuse bit of previous chunk */ 1351 1352#define prev_inuse(p) ((p)->size & PREV_INUSE) 1353 1354/* check for mmap()'ed chunk */ 1355 1356#define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED) 1357 1358/* set/clear chunk as in use without otherwise disturbing */ 1359 1360#define set_inuse(p)\ 1361((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE 1362 1363#define clear_inuse(p)\ 1364((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE) 1365 1366/* check/set/clear inuse bits in known places */ 1367 1368#define inuse_bit_at_offset(p, s)\ 1369 (((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE) 1370 1371#define set_inuse_bit_at_offset(p, s)\ 1372 (((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE) 1373 1374#define clear_inuse_bit_at_offset(p, s)\ 1375 (((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE)) 1376 1377 1378 1379 1380/* 1381 Dealing with size fields 1382*/ 1383 1384/* Get size, ignoring use bits */ 1385 1386#define chunksize(p) ((p)->size & ~(SIZE_BITS)) 1387 1388/* Set size at head, without disturbing its use bit */ 1389 1390#define set_head_size(p, s) ((p)->size = (((p)->size & PREV_INUSE) | (s))) 1391 1392/* Set size/use ignoring previous bits in header */ 1393 1394#define set_head(p, s) ((p)->size = (s)) 1395 1396/* Set size at footer (only when chunk is not in use) */ 1397 1398#define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_size = (s)) 1399 1400 1401 1402 1403 1404/* 1405 Bins 1406 1407 The bins, `av_' are an array of pairs of pointers serving as the 1408 heads of (initially empty) doubly-linked lists of chunks, laid out 1409 in a way so that each pair can be treated as if it were in a 1410 malloc_chunk. (This way, the fd/bk offsets for linking bin heads 1411 and chunks are the same). 1412 1413 Bins for sizes < 512 bytes contain chunks of all the same size, spaced 1414 8 bytes apart. Larger bins are approximately logarithmically 1415 spaced. (See the table below.) The `av_' array is never mentioned 1416 directly in the code, but instead via bin access macros. 1417 1418 Bin layout: 1419 1420 64 bins of size 8 1421 32 bins of size 64 1422 16 bins of size 512 1423 8 bins of size 4096 1424 4 bins of size 32768 1425 2 bins of size 262144 1426 1 bin of size what's left 1427 1428 There is actually a little bit of slop in the numbers in bin_index 1429 for the sake of speed. This makes no difference elsewhere. 1430 1431 The special chunks `top' and `last_remainder' get their own bins, 1432 (this is implemented via yet more trickery with the av_ array), 1433 although `top' is never properly linked to its bin since it is 1434 always handled specially. 1435 1436*/ 1437 1438#define NAV 128 /* number of bins */ 1439 1440typedef struct malloc_chunk* mbinptr; 1441 1442/* access macros */ 1443 1444#define bin_at(i) ((mbinptr)((char*)&(av_[2*(i) + 2]) - 2*SIZE_SZ)) 1445#define next_bin(b) ((mbinptr)((char*)(b) + 2 * sizeof(mbinptr))) 1446#define prev_bin(b) ((mbinptr)((char*)(b) - 2 * sizeof(mbinptr))) 1447 1448/* 1449 The first 2 bins are never indexed. The corresponding av_ cells are instead 1450 used for bookkeeping. This is not to save space, but to simplify 1451 indexing, maintain locality, and avoid some initialization tests. 1452*/ 1453 1454#define top (bin_at(0)->fd) /* The topmost chunk */ 1455#define last_remainder (bin_at(1)) /* remainder from last split */ 1456 1457 1458/* 1459 Because top initially points to its own bin with initial 1460 zero size, thus forcing extension on the first malloc request, 1461 we avoid having any special code in malloc to check whether 1462 it even exists yet. But we still need to in malloc_extend_top. 1463*/ 1464 1465#define initial_top ((mchunkptr)(bin_at(0))) 1466 1467/* Helper macro to initialize bins */ 1468 1469#define IAV(i) bin_at(i), bin_at(i) 1470 1471static mbinptr av_[NAV * 2 + 2] = { 1472 0, 0, 1473 IAV(0), IAV(1), IAV(2), IAV(3), IAV(4), IAV(5), IAV(6), IAV(7), 1474 IAV(8), IAV(9), IAV(10), IAV(11), IAV(12), IAV(13), IAV(14), IAV(15), 1475 IAV(16), IAV(17), IAV(18), IAV(19), IAV(20), IAV(21), IAV(22), IAV(23), 1476 IAV(24), IAV(25), IAV(26), IAV(27), IAV(28), IAV(29), IAV(30), IAV(31), 1477 IAV(32), IAV(33), IAV(34), IAV(35), IAV(36), IAV(37), IAV(38), IAV(39), 1478 IAV(40), IAV(41), IAV(42), IAV(43), IAV(44), IAV(45), IAV(46), IAV(47), 1479 IAV(48), IAV(49), IAV(50), IAV(51), IAV(52), IAV(53), IAV(54), IAV(55), 1480 IAV(56), IAV(57), IAV(58), IAV(59), IAV(60), IAV(61), IAV(62), IAV(63), 1481 IAV(64), IAV(65), IAV(66), IAV(67), IAV(68), IAV(69), IAV(70), IAV(71), 1482 IAV(72), IAV(73), IAV(74), IAV(75), IAV(76), IAV(77), IAV(78), IAV(79), 1483 IAV(80), IAV(81), IAV(82), IAV(83), IAV(84), IAV(85), IAV(86), IAV(87), 1484 IAV(88), IAV(89), IAV(90), IAV(91), IAV(92), IAV(93), IAV(94), IAV(95), 1485 IAV(96), IAV(97), IAV(98), IAV(99), IAV(100), IAV(101), IAV(102), IAV(103), 1486 IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111), 1487 IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119), 1488 IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127) 1489}; 1490 1491 1492 1493/* field-extraction macros */ 1494 1495#define first(b) ((b)->fd) 1496#define last(b) ((b)->bk) 1497 1498/* 1499 Indexing into bins 1500*/ 1501 1502#define bin_index(sz) \ 1503(((((unsigned long)(sz)) >> 9) == 0) ? (((unsigned long)(sz)) >> 3): \ 1504 ((((unsigned long)(sz)) >> 9) <= 4) ? 56 + (((unsigned long)(sz)) >> 6): \ 1505 ((((unsigned long)(sz)) >> 9) <= 20) ? 91 + (((unsigned long)(sz)) >> 9): \ 1506 ((((unsigned long)(sz)) >> 9) <= 84) ? 110 + (((unsigned long)(sz)) >> 12): \ 1507 ((((unsigned long)(sz)) >> 9) <= 340) ? 119 + (((unsigned long)(sz)) >> 15): \ 1508 ((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18): \ 1509 126) 1510/* 1511 bins for chunks < 512 are all spaced 8 bytes apart, and hold 1512 identically sized chunks. This is exploited in malloc. 1513*/ 1514 1515#define MAX_SMALLBIN 63 1516#define MAX_SMALLBIN_SIZE 512 1517#define SMALLBIN_WIDTH 8 1518 1519#define smallbin_index(sz) (((unsigned long)(sz)) >> 3) 1520 1521/* 1522 Requests are `small' if both the corresponding and the next bin are small 1523*/ 1524 1525#define is_small_request(nb) (nb < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH) 1526 1527 1528 1529/* 1530 To help compensate for the large number of bins, a one-level index 1531 structure is used for bin-by-bin searching. `binblocks' is a 1532 one-word bitvector recording whether groups of BINBLOCKWIDTH bins 1533 have any (possibly) non-empty bins, so they can be skipped over 1534 all at once during during traversals. The bits are NOT always 1535 cleared as soon as all bins in a block are empty, but instead only 1536 when all are noticed to be empty during traversal in malloc. 1537*/ 1538 1539#define BINBLOCKWIDTH 4 /* bins per block */ 1540 1541#define binblocks (bin_at(0)->size) /* bitvector of nonempty blocks */ 1542 1543/* bin<->block macros */ 1544 1545#define idx2binblock(ix) ((unsigned)1 << (ix / BINBLOCKWIDTH)) 1546#define mark_binblock(ii) (binblocks |= idx2binblock(ii)) 1547#define clear_binblock(ii) (binblocks &= ~(idx2binblock(ii))) 1548 1549 1550 1551 1552 1553/* Other static bookkeeping data */ 1554 1555/* variables holding tunable values */ 1556 1557static unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD; 1558static unsigned long top_pad = DEFAULT_TOP_PAD; 1559static unsigned int n_mmaps_max = DEFAULT_MMAP_MAX; 1560static unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD; 1561 1562/* The first value returned from sbrk */ 1563static char* sbrk_base = (char*)(-1); 1564 1565/* The maximum memory obtained from system via sbrk */ 1566static unsigned long max_sbrked_mem = 0; 1567 1568/* The maximum via either sbrk or mmap */ 1569static unsigned long max_total_mem = 0; 1570 1571/* internal working copy of mallinfo */ 1572static struct mallinfo current_mallinfo = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; 1573 1574/* The total memory obtained from system via sbrk */ 1575#define sbrked_mem (current_mallinfo.arena) 1576 1577/* Tracking mmaps */ 1578 1579static unsigned int n_mmaps = 0; 1580static unsigned int max_n_mmaps = 0; 1581static unsigned long mmapped_mem = 0; 1582static unsigned long max_mmapped_mem = 0; 1583 1584 1585 1586/* 1587 Debugging support 1588*/ 1589 1590#if DEBUG 1591 1592 1593/* 1594 These routines make a number of assertions about the states 1595 of data structures that should be true at all times. If any 1596 are not true, it's very likely that a user program has somehow 1597 trashed memory. (It's also possible that there is a coding error 1598 in malloc. In which case, please report it!) 1599*/ 1600 1601#if __STD_C 1602static void do_check_chunk(mchunkptr p) 1603#else 1604static void do_check_chunk(p) mchunkptr p; 1605#endif 1606{ 1607 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE; 1608 1609 /* No checkable chunk is mmapped */ 1610 assert(!chunk_is_mmapped(p)); 1611 1612 /* Check for legal address ... */ 1613 assert((char*)p >= sbrk_base); 1614 if (p != top) 1615 assert((char*)p + sz <= (char*)top); 1616 else 1617 assert((char*)p + sz <= sbrk_base + sbrked_mem); 1618 1619} 1620 1621 1622#if __STD_C 1623static void do_check_free_chunk(mchunkptr p) 1624#else 1625static void do_check_free_chunk(p) mchunkptr p; 1626#endif 1627{ 1628 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE; 1629 mchunkptr next = chunk_at_offset(p, sz); 1630 1631 do_check_chunk(p); 1632 1633 /* Check whether it claims to be free ... */ 1634 assert(!inuse(p)); 1635 1636 /* Unless a special marker, must have OK fields */ 1637 if ((long)sz >= (long)MINSIZE) 1638 { 1639 assert((sz & MALLOC_ALIGN_MASK) == 0); 1640 assert(aligned_OK(chunk2mem(p))); 1641 /* ... matching footer field */ 1642 assert(next->prev_size == sz); 1643 /* ... and is fully consolidated */ 1644 assert(prev_inuse(p)); 1645 assert (next == top || inuse(next)); 1646 1647 /* ... and has minimally sane links */ 1648 assert(p->fd->bk == p); 1649 assert(p->bk->fd == p); 1650 } 1651 else /* markers are always of size SIZE_SZ */ 1652 assert(sz == SIZE_SZ); 1653} 1654 1655#if __STD_C 1656static void do_check_inuse_chunk(mchunkptr p) 1657#else 1658static void do_check_inuse_chunk(p) mchunkptr p; 1659#endif 1660{ 1661 mchunkptr next = next_chunk(p); 1662 do_check_chunk(p); 1663 1664 /* Check whether it claims to be in use ... */ 1665 assert(inuse(p)); 1666 1667 /* ... and is surrounded by OK chunks. 1668 Since more things can be checked with free chunks than inuse ones, 1669 if an inuse chunk borders them and debug is on, it's worth doing them. 1670 */ 1671 if (!prev_inuse(p)) 1672 { 1673 mchunkptr prv = prev_chunk(p); 1674 assert(next_chunk(prv) == p); 1675 do_check_free_chunk(prv); 1676 } 1677 if (next == top) 1678 { 1679 assert(prev_inuse(next)); 1680 assert(chunksize(next) >= MINSIZE); 1681 } 1682 else if (!inuse(next)) 1683 do_check_free_chunk(next); 1684 1685} 1686 1687#if __STD_C 1688static void do_check_malloced_chunk(mchunkptr p, INTERNAL_SIZE_T s) 1689#else 1690static void do_check_malloced_chunk(p, s) mchunkptr p; INTERNAL_SIZE_T s; 1691#endif 1692{ 1693 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE; 1694 long room = sz - s; 1695 1696 do_check_inuse_chunk(p); 1697 1698 /* Legal size ... */ 1699 assert((long)sz >= (long)MINSIZE); 1700 assert((sz & MALLOC_ALIGN_MASK) == 0); 1701 assert(room >= 0); 1702 assert(room < (long)MINSIZE); 1703 1704 /* ... and alignment */ 1705 assert(aligned_OK(chunk2mem(p))); 1706 1707 1708 /* ... and was allocated at front of an available chunk */ 1709 assert(prev_inuse(p)); 1710 1711} 1712 1713 1714#define check_free_chunk(P) do_check_free_chunk(P) 1715#define check_inuse_chunk(P) do_check_inuse_chunk(P) 1716#define check_chunk(P) do_check_chunk(P) 1717#define check_malloced_chunk(P,N) do_check_malloced_chunk(P,N) 1718#else 1719#define check_free_chunk(P) 1720#define check_inuse_chunk(P) 1721#define check_chunk(P) 1722#define check_malloced_chunk(P,N) 1723#endif 1724 1725 1726 1727/* 1728 Macro-based internal utilities 1729*/ 1730 1731 1732/* 1733 Linking chunks in bin lists. 1734 Call these only with variables, not arbitrary expressions, as arguments. 1735*/ 1736 1737/* 1738 Place chunk p of size s in its bin, in size order, 1739 putting it ahead of others of same size. 1740*/ 1741 1742 1743#define frontlink(P, S, IDX, BK, FD) \ 1744{ \ 1745 if (S < MAX_SMALLBIN_SIZE) \ 1746 { \ 1747 IDX = smallbin_index(S); \ 1748 mark_binblock(IDX); \ 1749 BK = bin_at(IDX); \ 1750 FD = BK->fd; \ 1751 P->bk = BK; \ 1752 P->fd = FD; \ 1753 FD->bk = BK->fd = P; \ 1754 } \ 1755 else \ 1756 { \ 1757 IDX = bin_index(S); \ 1758 BK = bin_at(IDX); \ 1759 FD = BK->fd; \ 1760 if (FD == BK) mark_binblock(IDX); \ 1761 else \ 1762 { \ 1763 while (FD != BK && S < chunksize(FD)) FD = FD->fd; \ 1764 BK = FD->bk; \ 1765 } \ 1766 P->bk = BK; \ 1767 P->fd = FD; \ 1768 FD->bk = BK->fd = P; \ 1769 } \ 1770} 1771 1772 1773/* take a chunk off a list */ 1774 1775#define unlink(P, BK, FD) \ 1776{ \ 1777 BK = P->bk; \ 1778 FD = P->fd; \ 1779 FD->bk = BK; \ 1780 BK->fd = FD; \ 1781} \ 1782 1783/* Place p as the last remainder */ 1784 1785#define link_last_remainder(P) \ 1786{ \ 1787 last_remainder->fd = last_remainder->bk = P; \ 1788 P->fd = P->bk = last_remainder; \ 1789} 1790 1791/* Clear the last_remainder bin */ 1792 1793#define clear_last_remainder \ 1794 (last_remainder->fd = last_remainder->bk = last_remainder) 1795 1796 1797 1798 1799 1800 1801/* Routines dealing with mmap(). */ 1802 1803#if HAVE_MMAP 1804 1805#if __STD_C 1806static mchunkptr mmap_chunk(size_t size) 1807#else 1808static mchunkptr mmap_chunk(size) size_t size; 1809#endif 1810{ 1811 size_t page_mask = malloc_getpagesize - 1; 1812 mchunkptr p; 1813 1814#ifndef MAP_ANONYMOUS 1815 static int fd = -1; 1816#endif 1817 1818 if(n_mmaps >= n_mmaps_max) return 0; /* too many regions */ 1819 1820 /* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because 1821 * there is no following chunk whose prev_size field could be used. 1822 */ 1823 size = (size + SIZE_SZ + page_mask) & ~page_mask; 1824 1825#ifdef MAP_ANONYMOUS 1826 p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, 1827 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 1828#else /* !MAP_ANONYMOUS */ 1829 if (fd < 0) 1830 { 1831 fd = open("/dev/zero", O_RDWR); 1832 if(fd < 0) return 0; 1833 } 1834 p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); 1835#endif 1836 1837 if(p == (mchunkptr)-1) return 0; 1838 1839 n_mmaps++; 1840 if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps; 1841 1842 /* We demand that eight bytes into a page must be 8-byte aligned. */ 1843 assert(aligned_OK(chunk2mem(p))); 1844 1845 /* The offset to the start of the mmapped region is stored 1846 * in the prev_size field of the chunk; normally it is zero, 1847 * but that can be changed in memalign(). 1848 */ 1849 p->prev_size = 0; 1850 set_head(p, size|IS_MMAPPED); 1851 1852 mmapped_mem += size; 1853 if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem) 1854 max_mmapped_mem = mmapped_mem; 1855 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) 1856 max_total_mem = mmapped_mem + sbrked_mem; 1857 return p; 1858} 1859 1860#if __STD_C 1861static void munmap_chunk(mchunkptr p) 1862#else 1863static void munmap_chunk(p) mchunkptr p; 1864#endif 1865{ 1866 INTERNAL_SIZE_T size = chunksize(p); 1867 int ret; 1868 1869 assert (chunk_is_mmapped(p)); 1870 assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem)); 1871 assert((n_mmaps > 0)); 1872 assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0); 1873 1874 n_mmaps--; 1875 mmapped_mem -= (size + p->prev_size); 1876 1877 ret = munmap((char *)p - p->prev_size, size + p->prev_size); 1878 1879 /* munmap returns non-zero on failure */ 1880 assert(ret == 0); 1881} 1882 1883#if HAVE_MREMAP 1884 1885#if __STD_C 1886static mchunkptr mremap_chunk(mchunkptr p, size_t new_size) 1887#else 1888static mchunkptr mremap_chunk(p, new_size) mchunkptr p; size_t new_size; 1889#endif 1890{ 1891 size_t page_mask = malloc_getpagesize - 1; 1892 INTERNAL_SIZE_T offset = p->prev_size; 1893 INTERNAL_SIZE_T size = chunksize(p); 1894 char *cp; 1895 1896 assert (chunk_is_mmapped(p)); 1897 assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem)); 1898 assert((n_mmaps > 0)); 1899 assert(((size + offset) & (malloc_getpagesize-1)) == 0); 1900 1901 /* Note the extra SIZE_SZ overhead as in mmap_chunk(). */ 1902 new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask; 1903 1904 cp = (char *)mremap((char *)p - offset, size + offset, new_size, 1); 1905 1906 if (cp == (char *)-1) return 0; 1907 1908 p = (mchunkptr)(cp + offset); 1909 1910 assert(aligned_OK(chunk2mem(p))); 1911 1912 assert((p->prev_size == offset)); 1913 set_head(p, (new_size - offset)|IS_MMAPPED); 1914 1915 mmapped_mem -= size + offset; 1916 mmapped_mem += new_size; 1917 if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem) 1918 max_mmapped_mem = mmapped_mem; 1919 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) 1920 max_total_mem = mmapped_mem + sbrked_mem; 1921 return p; 1922} 1923 1924#endif /* HAVE_MREMAP */ 1925 1926#endif /* HAVE_MMAP */ 1927 1928 1929 1930 1931/* 1932 Extend the top-most chunk by obtaining memory from system. 1933 Main interface to sbrk (but see also malloc_trim). 1934*/ 1935 1936#if __STD_C 1937static void malloc_extend_top(INTERNAL_SIZE_T nb) 1938#else 1939static void malloc_extend_top(nb) INTERNAL_SIZE_T nb; 1940#endif 1941{ 1942 char* brk; /* return value from sbrk */ 1943 INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */ 1944 INTERNAL_SIZE_T correction; /* bytes for 2nd sbrk call */ 1945 char* new_brk; /* return of 2nd sbrk call */ 1946 INTERNAL_SIZE_T top_size; /* new size of top chunk */ 1947 1948 mchunkptr old_top = top; /* Record state of old top */ 1949 INTERNAL_SIZE_T old_top_size = chunksize(old_top); 1950 char* old_end = (char*)(chunk_at_offset(old_top, old_top_size)); 1951 1952 /* Pad request with top_pad plus minimal overhead */ 1953 1954 INTERNAL_SIZE_T sbrk_size = nb + top_pad + MINSIZE; 1955 unsigned long pagesz = malloc_getpagesize; 1956 1957 /* If not the first time through, round to preserve page boundary */ 1958 /* Otherwise, we need to correct to a page size below anyway. */ 1959 /* (We also correct below if an intervening foreign sbrk call.) */ 1960 1961 if (sbrk_base != (char*)(-1)) 1962 sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1); 1963 1964 brk = (char*)(MORECORE (sbrk_size)); 1965 1966 /* Fail if sbrk failed or if a foreign sbrk call killed our space */ 1967 if (brk == (char*)(MORECORE_FAILURE) || 1968 (brk < old_end && old_top != initial_top)) 1969 return; 1970 1971 sbrked_mem += sbrk_size; 1972 1973 if (brk == old_end) /* can just add bytes to current top */ 1974 { 1975 top_size = sbrk_size + old_top_size; 1976 set_head(top, top_size | PREV_INUSE); 1977 } 1978 else 1979 { 1980 if (sbrk_base == (char*)(-1)) /* First time through. Record base */ 1981 sbrk_base = brk; 1982 else /* Someone else called sbrk(). Count those bytes as sbrked_mem. */ 1983 sbrked_mem += brk - (char*)old_end; 1984 1985 /* Guarantee alignment of first new chunk made from this space */ 1986 front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK; 1987 if (front_misalign > 0) 1988 { 1989 correction = (MALLOC_ALIGNMENT) - front_misalign; 1990 brk += correction; 1991 } 1992 else 1993 correction = 0; 1994 1995 /* Guarantee the next brk will be at a page boundary */ 1996 1997 correction += ((((unsigned long)(brk + sbrk_size))+(pagesz-1)) & 1998 ~(pagesz - 1)) - ((unsigned long)(brk + sbrk_size)); 1999 2000 /* Allocate correction */ 2001 new_brk = (char*)(MORECORE (correction)); 2002 if (new_brk == (char*)(MORECORE_FAILURE)) return; 2003 2004 sbrked_mem += correction; 2005 2006 top = (mchunkptr)brk; 2007 top_size = new_brk - brk + correction; 2008 set_head(top, top_size | PREV_INUSE); 2009 2010 if (old_top != initial_top) 2011 { 2012 2013 /* There must have been an intervening foreign sbrk call. */ 2014 /* A double fencepost is necessary to prevent consolidation */ 2015 2016 /* If not enough space to do this, then user did something very wrong */ 2017 if (old_top_size < MINSIZE) 2018 { 2019 set_head(top, PREV_INUSE); /* will force null return from malloc */ 2020 return; 2021 } 2022 2023 /* Also keep size a multiple of MALLOC_ALIGNMENT */ 2024 old_top_size = (old_top_size - 3*SIZE_SZ) & ~MALLOC_ALIGN_MASK; 2025 set_head_size(old_top, old_top_size); 2026 chunk_at_offset(old_top, old_top_size )->size = 2027 SIZE_SZ|PREV_INUSE; 2028 chunk_at_offset(old_top, old_top_size + SIZE_SZ)->size = 2029 SIZE_SZ|PREV_INUSE; 2030 /* If possible, release the rest. */ 2031 if (old_top_size >= MINSIZE) 2032 fREe(chunk2mem(old_top)); 2033 } 2034 } 2035 2036 if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem) 2037 max_sbrked_mem = sbrked_mem; 2038 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) 2039 max_total_mem = mmapped_mem + sbrked_mem; 2040 2041 /* We always land on a page boundary */ 2042 assert(((unsigned long)((char*)top + top_size) & (pagesz - 1)) == 0); 2043} 2044 2045 2046 2047 2048/* Main public routines */ 2049 2050 2051/* 2052 Malloc Algorthim: 2053 2054 The requested size is first converted into a usable form, `nb'. 2055 This currently means to add 4 bytes overhead plus possibly more to 2056 obtain 8-byte alignment and/or to obtain a size of at least 2057 MINSIZE (currently 16 bytes), the smallest allocatable size. 2058 (All fits are considered `exact' if they are within MINSIZE bytes.) 2059 2060 From there, the first successful of the following steps is taken: 2061 2062 1. The bin corresponding to the request size is scanned, and if 2063 a chunk of exactly the right size is found, it is taken. 2064 2065 2. The most recently remaindered chunk is used if it is big 2066 enough. This is a form of (roving) first fit, used only in 2067 the absence of exact fits. Runs of consecutive requests use 2068 the remainder of the chunk used for the previous such request 2069 whenever possible. This limited use of a first-fit style 2070 allocation strategy tends to give contiguous chunks 2071 coextensive lifetimes, which improves locality and can reduce 2072 fragmentation in the long run. 2073 2074 3. Other bins are scanned in increasing size order, using a 2075 chunk big enough to fulfill the request, and splitting off 2076 any remainder. This search is strictly by best-fit; i.e., 2077 the smallest (with ties going to approximately the least 2078 recently used) chunk that fits is selected. 2079 2080 4. If large enough, the chunk bordering the end of memory 2081 (`top') is split off. (This use of `top' is in accord with 2082 the best-fit search rule. In effect, `top' is treated as 2083 larger (and thus less well fitting) than any other available 2084 chunk since it can be extended to be as large as necessary 2085 (up to system limitations). 2086 2087 5. If the request size meets the mmap threshold and the 2088 system supports mmap, and there are few enough currently 2089 allocated mmapped regions, and a call to mmap succeeds, 2090 the request is allocated via direct memory mapping. 2091 2092 6. Otherwise, the top of memory is extended by 2093 obtaining more space from the system (normally using sbrk, 2094 but definable to anything else via the MORECORE macro). 2095 Memory is gathered from the system (in system page-sized 2096 units) in a way that allows chunks obtained across different 2097 sbrk calls to be consolidated, but does not require 2098 contiguous memory. Thus, it should be safe to intersperse 2099 mallocs with other sbrk calls. 2100 2101 2102 All allocations are made from the the `lowest' part of any found 2103 chunk. (The implementation invariant is that prev_inuse is 2104 always true of any allocated chunk; i.e., that each allocated 2105 chunk borders either a previously allocated and still in-use chunk, 2106 or the base of its memory arena.) 2107 2108*/ 2109 2110#if __STD_C 2111Void_t* mALLOc(size_t bytes) 2112#else 2113Void_t* mALLOc(bytes) size_t bytes; 2114#endif 2115{ 2116 mchunkptr victim; /* inspected/selected chunk */ 2117 INTERNAL_SIZE_T victim_size; /* its size */ 2118 int idx; /* index for bin traversal */ 2119 mbinptr bin; /* associated bin */ 2120 mchunkptr remainder; /* remainder from a split */ 2121 long remainder_size; /* its size */ 2122 int remainder_index; /* its bin index */ 2123 unsigned long block; /* block traverser bit */ 2124 int startidx; /* first bin of a traversed block */ 2125 mchunkptr fwd; /* misc temp for linking */ 2126 mchunkptr bck; /* misc temp for linking */ 2127 mbinptr q; /* misc temp */ 2128 2129 INTERNAL_SIZE_T nb; 2130 2131 if ((long)bytes < 0) return 0; 2132 2133 nb = request2size(bytes); /* padded request size; */ 2134 2135 /* Check for exact match in a bin */ 2136 2137 if (is_small_request(nb)) /* Faster version for small requests */ 2138 { 2139 idx = smallbin_index(nb); 2140 2141 /* No traversal or size check necessary for small bins. */ 2142 2143 q = bin_at(idx); 2144 victim = last(q); 2145 2146 /* Also scan the next one, since it would have a remainder < MINSIZE */ 2147 if (victim == q) 2148 { 2149 q = next_bin(q); 2150 victim = last(q); 2151 } 2152 if (victim != q) 2153 { 2154 victim_size = chunksize(victim); 2155 unlink(victim, bck, fwd); 2156 set_inuse_bit_at_offset(victim, victim_size); 2157 check_malloced_chunk(victim, nb); 2158 return chunk2mem(victim); 2159 } 2160 2161 idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */ 2162 2163 } 2164 else 2165 { 2166 idx = bin_index(nb); 2167 bin = bin_at(idx); 2168 2169 for (victim = last(bin); victim != bin; victim = victim->bk) 2170 { 2171 victim_size = chunksize(victim); 2172 remainder_size = victim_size - nb; 2173 2174 if (remainder_size >= (long)MINSIZE) /* too big */ 2175 { 2176 --idx; /* adjust to rescan below after checking last remainder */ 2177 break; 2178 } 2179 2180 else if (remainder_size >= 0) /* exact fit */ 2181 { 2182 unlink(victim, bck, fwd); 2183 set_inuse_bit_at_offset(victim, victim_size); 2184 check_malloced_chunk(victim, nb); 2185 return chunk2mem(victim); 2186 } 2187 } 2188 2189 ++idx; 2190 2191 } 2192 2193 /* Try to use the last split-off remainder */ 2194 2195 if ( (victim = last_remainder->fd) != last_remainder) 2196 { 2197 victim_size = chunksize(victim); 2198 remainder_size = victim_size - nb; 2199 2200 if (remainder_size >= (long)MINSIZE) /* re-split */ 2201 { 2202 remainder = chunk_at_offset(victim, nb); 2203 set_head(victim, nb | PREV_INUSE); 2204 link_last_remainder(remainder); 2205 set_head(remainder, remainder_size | PREV_INUSE); 2206 set_foot(remainder, remainder_size); 2207 check_malloced_chunk(victim, nb); 2208 return chunk2mem(victim); 2209 } 2210 2211 clear_last_remainder; 2212 2213 if (remainder_size >= 0) /* exhaust */ 2214 { 2215 set_inuse_bit_at_offset(victim, victim_size); 2216 check_malloced_chunk(victim, nb); 2217 return chunk2mem(victim); 2218 } 2219 2220 /* Else place in bin */ 2221 2222 frontlink(victim, victim_size, remainder_index, bck, fwd); 2223 } 2224 2225 /* 2226 If there are any possibly nonempty big-enough blocks, 2227 search for best fitting chunk by scanning bins in blockwidth units. 2228 */ 2229 2230 if ( (block = idx2binblock(idx)) <= binblocks) 2231 { 2232 2233 /* Get to the first marked block */ 2234 2235 if ( (block & binblocks) == 0) 2236 { 2237 /* force to an even block boundary */ 2238 idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH; 2239 block <<= 1; 2240 while ((block & binblocks) == 0) 2241 { 2242 idx += BINBLOCKWIDTH; 2243 block <<= 1; 2244 } 2245 } 2246 2247 /* For each possibly nonempty block ... */ 2248 for (;;) 2249 { 2250 startidx = idx; /* (track incomplete blocks) */ 2251 q = bin = bin_at(idx); 2252 2253 /* For each bin in this block ... */ 2254 do 2255 { 2256 /* Find and use first big enough chunk ... */ 2257 2258 for (victim = last(bin); victim != bin; victim = victim->bk) 2259 { 2260 victim_size = chunksize(victim); 2261 remainder_size = victim_size - nb; 2262 2263 if (remainder_size >= (long)MINSIZE) /* split */ 2264 { 2265 remainder = chunk_at_offset(victim, nb); 2266 set_head(victim, nb | PREV_INUSE); 2267 unlink(victim, bck, fwd); 2268 link_last_remainder(remainder); 2269 set_head(remainder, remainder_size | PREV_INUSE); 2270 set_foot(remainder, remainder_size); 2271 check_malloced_chunk(victim, nb); 2272 return chunk2mem(victim); 2273 } 2274 2275 else if (remainder_size >= 0) /* take */ 2276 { 2277 set_inuse_bit_at_offset(victim, victim_size); 2278 unlink(victim, bck, fwd); 2279 check_malloced_chunk(victim, nb); 2280 return chunk2mem(victim); 2281 } 2282 2283 } 2284 2285 bin = next_bin(bin); 2286 2287 } while ((++idx & (BINBLOCKWIDTH - 1)) != 0); 2288 2289 /* Clear out the block bit. */ 2290 2291 do /* Possibly backtrack to try to clear a partial block */ 2292 { 2293 if ((startidx & (BINBLOCKWIDTH - 1)) == 0) 2294 { 2295 binblocks &= ~block; 2296 break; 2297 } 2298 --startidx; 2299 q = prev_bin(q); 2300 } while (first(q) == q); 2301 2302 /* Get to the next possibly nonempty block */ 2303 2304 if ( (block <<= 1) <= binblocks && (block != 0) ) 2305 { 2306 while ((block & binblocks) == 0) 2307 { 2308 idx += BINBLOCKWIDTH; 2309 block <<= 1; 2310 } 2311 } 2312 else 2313 break; 2314 } 2315 } 2316 2317 2318 /* Try to use top chunk */ 2319 2320 /* Require that there be a remainder, ensuring top always exists */ 2321 if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE) 2322 { 2323 2324#if HAVE_MMAP 2325 /* If big and would otherwise need to extend, try to use mmap instead */ 2326 if ((unsigned long)nb >= (unsigned long)mmap_threshold && 2327 (victim = mmap_chunk(nb)) != 0) 2328 return chunk2mem(victim); 2329#endif 2330 2331 /* Try to extend */ 2332 malloc_extend_top(nb); 2333 if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE) 2334 return 0; /* propagate failure */ 2335 } 2336 2337 victim = top; 2338 set_head(victim, nb | PREV_INUSE); 2339 top = chunk_at_offset(victim, nb); 2340 set_head(top, remainder_size | PREV_INUSE); 2341 check_malloced_chunk(victim, nb); 2342 return chunk2mem(victim); 2343 2344} 2345 2346 2347 2348 2349/* 2350 2351 free() algorithm : 2352 2353 cases: 2354 2355 1. free(0) has no effect. 2356 2357 2. If the chunk was allocated via mmap, it is release via munmap(). 2358 2359 3. If a returned chunk borders the current high end of memory, 2360 it is consolidated into the top, and if the total unused 2361 topmost memory exceeds the trim threshold, malloc_trim is 2362 called. 2363 2364 4. Other chunks are consolidated as they arrive, and 2365 placed in corresponding bins. (This includes the case of 2366 consolidating with the current `last_remainder'). 2367 2368*/ 2369 2370 2371#if __STD_C 2372void fREe(Void_t* mem) 2373#else 2374void fREe(mem) Void_t* mem; 2375#endif 2376{ 2377 mchunkptr p; /* chunk corresponding to mem */ 2378 INTERNAL_SIZE_T hd; /* its head field */ 2379 INTERNAL_SIZE_T sz; /* its size */ 2380 int idx; /* its bin index */ 2381 mchunkptr next; /* next contiguous chunk */ 2382 INTERNAL_SIZE_T nextsz; /* its size */ 2383 INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */ 2384 mchunkptr bck; /* misc temp for linking */ 2385 mchunkptr fwd; /* misc temp for linking */ 2386 int islr; /* track whether merging with last_remainder */ 2387 2388 if (mem == 0) /* free(0) has no effect */ 2389 return; 2390 2391 p = mem2chunk(mem); 2392 hd = p->size; 2393 2394#if HAVE_MMAP 2395 if (hd & IS_MMAPPED) /* release mmapped memory. */ 2396 { 2397 munmap_chunk(p); 2398 return; 2399 } 2400#endif 2401 2402 check_inuse_chunk(p); 2403 2404 sz = hd & ~PREV_INUSE; 2405 next = chunk_at_offset(p, sz); 2406 nextsz = chunksize(next); 2407 2408 if (next == top) /* merge with top */ 2409 { 2410 sz += nextsz; 2411 2412 if (!(hd & PREV_INUSE)) /* consolidate backward */ 2413 { 2414 prevsz = p->prev_size; 2415 p = chunk_at_offset(p, -((long) prevsz)); 2416 sz += prevsz; 2417 unlink(p, bck, fwd); 2418 } 2419 2420 set_head(p, sz | PREV_INUSE); 2421 top = p; 2422 if ((unsigned long)(sz) >= (unsigned long)trim_threshold) 2423 malloc_trim(top_pad); 2424 return; 2425 } 2426 2427 set_head(next, nextsz); /* clear inuse bit */ 2428 2429 islr = 0; 2430 2431 if (!(hd & PREV_INUSE)) /* consolidate backward */ 2432 { 2433 prevsz = p->prev_size; 2434 p = chunk_at_offset(p, -((long) prevsz)); 2435 sz += prevsz; 2436 2437 if (p->fd == last_remainder) /* keep as last_remainder */ 2438 islr = 1; 2439 else 2440 unlink(p, bck, fwd); 2441 } 2442 2443 if (!(inuse_bit_at_offset(next, nextsz))) /* consolidate forward */ 2444 { 2445 sz += nextsz; 2446 2447 if (!islr && next->fd == last_remainder) /* re-insert last_remainder */ 2448 { 2449 islr = 1; 2450 link_last_remainder(p); 2451 } 2452 else 2453 unlink(next, bck, fwd); 2454 } 2455 2456 2457 set_head(p, sz | PREV_INUSE); 2458 set_foot(p, sz); 2459 if (!islr) 2460 frontlink(p, sz, idx, bck, fwd); 2461} 2462 2463 2464 2465 2466 2467/* 2468 2469 Realloc algorithm: 2470 2471 Chunks that were obtained via mmap cannot be extended or shrunk 2472 unless HAVE_MREMAP is defined, in which case mremap is used. 2473 Otherwise, if their reallocation is for additional space, they are 2474 copied. If for less, they are just left alone. 2475 2476 Otherwise, if the reallocation is for additional space, and the 2477 chunk can be extended, it is, else a malloc-copy-free sequence is 2478 taken. There are several different ways that a chunk could be 2479 extended. All are tried: 2480 2481 * Extending forward into following adjacent free chunk. 2482 * Shifting backwards, joining preceding adjacent space 2483 * Both shifting backwards and extending forward. 2484 * Extending into newly sbrked space 2485 2486 Unless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with a 2487 size argument of zero (re)allocates a minimum-sized chunk. 2488 2489 If the reallocation is for less space, and the new request is for 2490 a `small' (<512 bytes) size, then the newly unused space is lopped 2491 off and freed. 2492 2493 The old unix realloc convention of allowing the last-free'd chunk 2494 to be used as an argument to realloc is no longer supported. 2495 I don't know of any programs still relying on this feature, 2496 and allowing it would also allow too many other incorrect 2497 usages of realloc to be sensible. 2498 2499 2500*/ 2501 2502 2503#if __STD_C 2504Void_t* rEALLOc(Void_t* oldmem, size_t bytes) 2505#else 2506Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes; 2507#endif 2508{ 2509 INTERNAL_SIZE_T nb; /* padded request size */ 2510 2511 mchunkptr oldp; /* chunk corresponding to oldmem */ 2512 INTERNAL_SIZE_T oldsize; /* its size */ 2513 2514 mchunkptr newp; /* chunk to return */ 2515 INTERNAL_SIZE_T newsize; /* its size */ 2516 Void_t* newmem; /* corresponding user mem */ 2517 2518 mchunkptr next; /* next contiguous chunk after oldp */ 2519 INTERNAL_SIZE_T nextsize; /* its size */ 2520 2521 mchunkptr prev; /* previous contiguous chunk before oldp */ 2522 INTERNAL_SIZE_T prevsize; /* its size */ 2523 2524 mchunkptr remainder; /* holds split off extra space from newp */ 2525 INTERNAL_SIZE_T remainder_size; /* its size */ 2526 2527 mchunkptr bck; /* misc temp for linking */ 2528 mchunkptr fwd; /* misc temp for linking */ 2529 2530#ifdef REALLOC_ZERO_BYTES_FREES 2531 if (bytes == 0) { fREe(oldmem); return 0; } 2532#endif 2533 2534 if ((long)bytes < 0) return 0; 2535 2536 /* realloc of null is supposed to be same as malloc */ 2537 if (oldmem == 0) return mALLOc(bytes); 2538 2539 newp = oldp = mem2chunk(oldmem); 2540 newsize = oldsize = chunksize(oldp); 2541 2542 2543 nb = request2size(bytes); 2544 2545#if HAVE_MMAP 2546 if (chunk_is_mmapped(oldp)) 2547 { 2548#if HAVE_MREMAP 2549 newp = mremap_chunk(oldp, nb); 2550 if(newp) return chunk2mem(newp); 2551#endif 2552 /* Note the extra SIZE_SZ overhead. */ 2553 if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing */ 2554 /* Must alloc, copy, free. */ 2555 newmem = mALLOc(bytes); 2556 if (newmem == 0) return 0; /* propagate failure */ 2557 MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ); 2558 munmap_chunk(oldp); 2559 return newmem; 2560 } 2561#endif 2562 2563 check_inuse_chunk(oldp); 2564 2565 if ((long)(oldsize) < (long)(nb)) 2566 { 2567 2568 /* Try expanding forward */ 2569 2570 next = chunk_at_offset(oldp, oldsize); 2571 if (next == top || !inuse(next)) 2572 { 2573 nextsize = chunksize(next); 2574 2575 /* Forward into top only if a remainder */ 2576 if (next == top) 2577 { 2578 if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE)) 2579 { 2580 newsize += nextsize; 2581 top = chunk_at_offset(oldp, nb); 2582 set_head(top, (newsize - nb) | PREV_INUSE); 2583 set_head_size(oldp, nb); 2584 return chunk2mem(oldp); 2585 } 2586 } 2587 2588 /* Forward into next chunk */ 2589 else if (((long)(nextsize + newsize) >= (long)(nb))) 2590 { 2591 unlink(next, bck, fwd); 2592 newsize += nextsize; 2593 goto split; 2594 } 2595 } 2596 else 2597 { 2598 next = 0; 2599 nextsize = 0; 2600 } 2601 2602 /* Try shifting backwards. */ 2603 2604 if (!prev_inuse(oldp)) 2605 { 2606 prev = prev_chunk(oldp); 2607 prevsize = chunksize(prev); 2608 2609 /* try forward + backward first to save a later consolidation */ 2610 2611 if (next != 0) 2612 { 2613 /* into top */ 2614 if (next == top) 2615 { 2616 if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE)) 2617 { 2618 unlink(prev, bck, fwd); 2619 newp = prev; 2620 newsize += prevsize + nextsize; 2621 newmem = chunk2mem(newp); 2622 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); 2623 top = chunk_at_offset(newp, nb); 2624 set_head(top, (newsize - nb) | PREV_INUSE); 2625 set_head_size(newp, nb); 2626 return newmem; 2627 } 2628 } 2629 2630 /* into next chunk */ 2631 else if (((long)(nextsize + prevsize + newsize) >= (long)(nb))) 2632 { 2633 unlink(next, bck, fwd); 2634 unlink(prev, bck, fwd); 2635 newp = prev; 2636 newsize += nextsize + prevsize; 2637 newmem = chunk2mem(newp); 2638 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); 2639 goto split; 2640 } 2641 } 2642 2643 /* backward only */ 2644 if (prev != 0 && (long)(prevsize + newsize) >= (long)nb) 2645 { 2646 unlink(prev, bck, fwd); 2647 newp = prev; 2648 newsize += prevsize; 2649 newmem = chunk2mem(newp); 2650 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); 2651 goto split; 2652 } 2653 } 2654 2655 /* Must allocate */ 2656 2657 newmem = mALLOc (bytes); 2658 2659 if (newmem == 0) /* propagate failure */ 2660 return 0; 2661 2662 /* Avoid copy if newp is next chunk after oldp. */ 2663 /* (This can only happen when new chunk is sbrk'ed.) */ 2664 2665 if ( (newp = mem2chunk(newmem)) == next_chunk(oldp)) 2666 { 2667 newsize += chunksize(newp); 2668 newp = oldp; 2669 goto split; 2670 } 2671 2672 /* Otherwise copy, free, and exit */ 2673 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); 2674 fREe(oldmem); 2675 return newmem; 2676 } 2677 2678 2679 split: /* split off extra room in old or expanded chunk */ 2680 2681 if (newsize - nb >= MINSIZE) /* split off remainder */ 2682 { 2683 remainder = chunk_at_offset(newp, nb); 2684 remainder_size = newsize - nb; 2685 set_head_size(newp, nb); 2686 set_head(remainder, remainder_size | PREV_INUSE); 2687 set_inuse_bit_at_offset(remainder, remainder_size); 2688 fREe(chunk2mem(remainder)); /* let free() deal with it */ 2689 } 2690 else 2691 { 2692 set_head_size(newp, newsize); 2693 set_inuse_bit_at_offset(newp, newsize); 2694 } 2695 2696 check_inuse_chunk(newp); 2697 return chunk2mem(newp); 2698} 2699 2700 2701 2702 2703/* 2704 2705 memalign algorithm: 2706 2707 memalign requests more than enough space from malloc, finds a spot 2708 within that chunk that meets the alignment request, and then 2709 possibly frees the leading and trailing space. 2710 2711 The alignment argument must be a power of two. This property is not 2712 checked by memalign, so misuse may result in random runtime errors. 2713 2714 8-byte alignment is guaranteed by normal malloc calls, so don't 2715 bother calling memalign with an argument of 8 or less. 2716 2717 Overreliance on memalign is a sure way to fragment space. 2718 2719*/ 2720 2721 2722#if __STD_C 2723Void_t* mEMALIGn(size_t alignment, size_t bytes) 2724#else 2725Void_t* mEMALIGn(alignment, bytes) size_t alignment; size_t bytes; 2726#endif 2727{ 2728 INTERNAL_SIZE_T nb; /* padded request size */ 2729 char* m; /* memory returned by malloc call */ 2730 mchunkptr p; /* corresponding chunk */ 2731 char* brk; /* alignment point within p */ 2732 mchunkptr newp; /* chunk to return */ 2733 INTERNAL_SIZE_T newsize; /* its size */ 2734 INTERNAL_SIZE_T leadsize; /* leading space befor alignment point */ 2735 mchunkptr remainder; /* spare room at end to split off */ 2736 long remainder_size; /* its size */ 2737 2738 if ((long)bytes < 0) return 0; 2739 2740 /* If need less alignment than we give anyway, just relay to malloc */ 2741 2742 if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes); 2743 2744 /* Otherwise, ensure that it is at least a minimum chunk size */ 2745 2746 if (alignment < MINSIZE) alignment = MINSIZE; 2747 2748 /* Call malloc with worst case padding to hit alignment. */ 2749 2750 nb = request2size(bytes); 2751 m = (char*)(mALLOc(nb + alignment + MINSIZE)); 2752 2753 if (m == 0) return 0; /* propagate failure */ 2754 2755 p = mem2chunk(m); 2756 2757 if ((((unsigned long)(m)) % alignment) == 0) /* aligned */ 2758 { 2759#if HAVE_MMAP 2760 if(chunk_is_mmapped(p)) 2761 return chunk2mem(p); /* nothing more to do */ 2762#endif 2763 } 2764 else /* misaligned */ 2765 { 2766 /* 2767 Find an aligned spot inside chunk. 2768 Since we need to give back leading space in a chunk of at 2769 least MINSIZE, if the first calculation places us at 2770 a spot with less than MINSIZE leader, we can move to the 2771 next aligned spot -- we've allocated enough total room so that 2772 this is always possible. 2773 */ 2774 2775 brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) & -((signed) alignment)); 2776 if ((long)(brk - (char*)(p)) < MINSIZE) brk = brk + alignment; 2777 2778 newp = (mchunkptr)brk; 2779 leadsize = brk - (char*)(p); 2780 newsize = chunksize(p) - leadsize; 2781 2782#if HAVE_MMAP 2783 if(chunk_is_mmapped(p)) 2784 { 2785 newp->prev_size = p->prev_size + leadsize; 2786 set_head(newp, newsize|IS_MMAPPED); 2787 return chunk2mem(newp); 2788 } 2789#endif 2790 2791 /* give back leader, use the rest */ 2792 2793 set_head(newp, newsize | PREV_INUSE); 2794 set_inuse_bit_at_offset(newp, newsize); 2795 set_head_size(p, leadsize); 2796 fREe(chunk2mem(p)); 2797 p = newp; 2798 2799 assert (newsize >= nb && (((unsigned long)(chunk2mem(p))) % alignment) == 0); 2800 } 2801 2802 /* Also give back spare room at the end */ 2803 2804 remainder_size = chunksize(p) - nb; 2805 2806 if (remainder_size >= (long)MINSIZE) 2807 { 2808 remainder = chunk_at_offset(p, nb); 2809 set_head(remainder, remainder_size | PREV_INUSE); 2810 set_head_size(p, nb); 2811 fREe(chunk2mem(remainder)); 2812 } 2813 2814 check_inuse_chunk(p); 2815 return chunk2mem(p); 2816 2817} 2818 2819 2820 2821 2822/* 2823 valloc just invokes memalign with alignment argument equal 2824 to the page size of the system (or as near to this as can 2825 be figured out from all the includes/defines above.) 2826*/ 2827 2828#if __STD_C 2829Void_t* vALLOc(size_t bytes) 2830#else 2831Void_t* vALLOc(bytes) size_t bytes; 2832#endif 2833{ 2834 return mEMALIGn (malloc_getpagesize, bytes); 2835} 2836 2837/* 2838 pvalloc just invokes valloc for the nearest pagesize 2839 that will accommodate request 2840*/ 2841 2842 2843#if __STD_C 2844Void_t* pvALLOc(size_t bytes) 2845#else 2846Void_t* pvALLOc(bytes) size_t bytes; 2847#endif 2848{ 2849 size_t pagesize = malloc_getpagesize; 2850 return mEMALIGn (pagesize, (bytes + pagesize - 1) & ~(pagesize - 1)); 2851} 2852 2853/* 2854 2855 calloc calls malloc, then zeroes out the allocated chunk. 2856 2857*/ 2858 2859#if __STD_C 2860Void_t* cALLOc(size_t n, size_t elem_size) 2861#else 2862Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size; 2863#endif 2864{ 2865 mchunkptr p; 2866 INTERNAL_SIZE_T csz; 2867 2868 INTERNAL_SIZE_T sz = n * elem_size; 2869 2870 2871 /* check if expand_top called, in which case don't need to clear */ 2872#if MORECORE_CLEARS 2873 mchunkptr oldtop = top; 2874 INTERNAL_SIZE_T oldtopsize = chunksize(top); 2875#endif 2876 Void_t* mem = mALLOc (sz); 2877 2878 if ((long)n < 0) return 0; 2879 2880 if (mem == 0) 2881 return 0; 2882 else 2883 { 2884 p = mem2chunk(mem); 2885 2886 /* Two optional cases in which clearing not necessary */ 2887 2888 2889#if HAVE_MMAP 2890 if (chunk_is_mmapped(p)) return mem; 2891#endif 2892 2893 csz = chunksize(p); 2894 2895#if MORECORE_CLEARS 2896 if (p == oldtop && csz > oldtopsize) 2897 { 2898 /* clear only the bytes from non-freshly-sbrked memory */ 2899 csz = oldtopsize; 2900 } 2901#endif 2902 2903 MALLOC_ZERO(mem, csz - SIZE_SZ); 2904 return mem; 2905 } 2906} 2907 2908/* 2909 2910 cfree just calls free. It is needed/defined on some systems 2911 that pair it with calloc, presumably for odd historical reasons. 2912 2913*/ 2914 2915#if !defined(INTERNAL_LINUX_C_LIB) || !defined(__ELF__) 2916#if __STD_C 2917void cfree(Void_t *mem) 2918#else 2919void cfree(mem) Void_t *mem; 2920#endif 2921{ 2922 fREe(mem); 2923} 2924#endif 2925 2926 2927 2928/* 2929 2930 Malloc_trim gives memory back to the system (via negative 2931 arguments to sbrk) if there is unused memory at the `high' end of 2932 the malloc pool. You can call this after freeing large blocks of 2933 memory to potentially reduce the system-level memory requirements 2934 of a program. However, it cannot guarantee to reduce memory. Under 2935 some allocation patterns, some large free blocks of memory will be 2936 locked between two used chunks, so they cannot be given back to 2937 the system. 2938 2939 The `pad' argument to malloc_trim represents the amount of free 2940 trailing space to leave untrimmed. If this argument is zero, 2941 only the minimum amount of memory to maintain internal data 2942 structures will be left (one page or less). Non-zero arguments 2943 can be supplied to maintain enough trailing space to service 2944 future expected allocations without having to re-obtain memory 2945 from the system. 2946 2947 Malloc_trim returns 1 if it actually released any memory, else 0. 2948 2949*/ 2950 2951#if __STD_C 2952int malloc_trim(size_t pad) 2953#else 2954int malloc_trim(pad) size_t pad; 2955#endif 2956{ 2957 long top_size; /* Amount of top-most memory */ 2958 long extra; /* Amount to release */ 2959 char* current_brk; /* address returned by pre-check sbrk call */ 2960 char* new_brk; /* address returned by negative sbrk call */ 2961 2962 unsigned long pagesz = malloc_getpagesize; 2963 2964 top_size = chunksize(top); 2965 extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz; 2966 2967 if (extra < (long)pagesz) /* Not enough memory to release */ 2968 return 0; 2969 2970 else 2971 { 2972 /* Test to make sure no one else called sbrk */ 2973 current_brk = (char*)(MORECORE (0)); 2974 if (current_brk != (char*)(top) + top_size) 2975 return 0; /* Apparently we don't own memory; must fail */ 2976 2977 else 2978 { 2979 new_brk = (char*)(MORECORE (-extra)); 2980 2981 if (new_brk == (char*)(MORECORE_FAILURE)) /* sbrk failed? */ 2982 { 2983 /* Try to figure out what we have */ 2984 current_brk = (char*)(MORECORE (0)); 2985 top_size = current_brk - (char*)top; 2986 if (top_size >= (long)MINSIZE) /* if not, we are very very dead! */ 2987 { 2988 sbrked_mem = current_brk - sbrk_base; 2989 set_head(top, top_size | PREV_INUSE); 2990 } 2991 check_chunk(top); 2992 return 0; 2993 } 2994 2995 else 2996 { 2997 /* Success. Adjust top accordingly. */ 2998 set_head(top, (top_size - extra) | PREV_INUSE); 2999 sbrked_mem -= extra; 3000 check_chunk(top); 3001 return 1; 3002 } 3003 } 3004 } 3005} 3006 3007 3008 3009/* 3010 malloc_usable_size: 3011 3012 This routine tells you how many bytes you can actually use in an 3013 allocated chunk, which may be more than you requested (although 3014 often not). You can use this many bytes without worrying about 3015 overwriting other allocated objects. Not a particularly great 3016 programming practice, but still sometimes useful. 3017 3018*/ 3019 3020#if __STD_C 3021size_t malloc_usable_size(Void_t* mem) 3022#else 3023size_t malloc_usable_size(mem) Void_t* mem; 3024#endif 3025{ 3026 mchunkptr p; 3027 if (mem == 0) 3028 return 0; 3029 else 3030 { 3031 p = mem2chunk(mem); 3032 if(!chunk_is_mmapped(p)) 3033 { 3034 if (!inuse(p)) return 0; 3035 check_inuse_chunk(p); 3036 return chunksize(p) - SIZE_SZ; 3037 } 3038 return chunksize(p) - 2*SIZE_SZ; 3039 } 3040} 3041 3042 3043 3044 3045/* Utility to update current_mallinfo for malloc_stats and mallinfo() */ 3046 3047static void malloc_update_mallinfo() 3048{ 3049 int i; 3050 mbinptr b; 3051 mchunkptr p; 3052#if DEBUG 3053 mchunkptr q; 3054#endif 3055 3056 INTERNAL_SIZE_T avail = chunksize(top); 3057 int navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0; 3058 3059 for (i = 1; i < NAV; ++i) 3060 { 3061 b = bin_at(i); 3062 for (p = last(b); p != b; p = p->bk) 3063 { 3064#if DEBUG 3065 check_free_chunk(p); 3066 for (q = next_chunk(p); 3067 q < top && inuse(q) && (long)(chunksize(q)) >= (long)MINSIZE; 3068 q = next_chunk(q)) 3069 check_inuse_chunk(q); 3070#endif 3071 avail += chunksize(p); 3072 navail++; 3073 } 3074 } 3075 3076 current_mallinfo.ordblks = navail; 3077 current_mallinfo.uordblks = sbrked_mem - avail; 3078 current_mallinfo.fordblks = avail; 3079 current_mallinfo.hblks = n_mmaps; 3080 current_mallinfo.hblkhd = mmapped_mem; 3081 current_mallinfo.keepcost = chunksize(top); 3082 3083} 3084 3085 3086 3087/* 3088 3089 malloc_stats: 3090 3091 Prints on stderr the amount of space obtain from the system (both 3092 via sbrk and mmap), the maximum amount (which may be more than 3093 current if malloc_trim and/or munmap got called), the maximum 3094 number of simultaneous mmap regions used, and the current number 3095 of bytes allocated via malloc (or realloc, etc) but not yet 3096 freed. (Note that this is the number of bytes allocated, not the 3097 number requested. It will be larger than the number requested 3098 because of alignment and bookkeeping overhead.) 3099 3100*/ 3101 3102void malloc_stats() 3103{ 3104 malloc_update_mallinfo(); 3105 fprintf(stderr, "max system bytes = %10u\n", 3106 (unsigned int)(max_total_mem)); 3107 fprintf(stderr, "system bytes = %10u\n", 3108 (unsigned int)(sbrked_mem + mmapped_mem)); 3109 fprintf(stderr, "in use bytes = %10u\n", 3110 (unsigned int)(current_mallinfo.uordblks + mmapped_mem)); 3111#if HAVE_MMAP 3112 fprintf(stderr, "max mmap regions = %10u\n", 3113 (unsigned int)max_n_mmaps); 3114#endif 3115} 3116 3117/* 3118 mallinfo returns a copy of updated current mallinfo. 3119*/ 3120 3121struct mallinfo mALLINFo() 3122{ 3123 malloc_update_mallinfo(); 3124 return current_mallinfo; 3125} 3126 3127 3128 3129 3130/* 3131 mallopt: 3132 3133 mallopt is the general SVID/XPG interface to tunable parameters. 3134 The format is to provide a (parameter-number, parameter-value) pair. 3135 mallopt then sets the corresponding parameter to the argument 3136 value if it can (i.e., so long as the value is meaningful), 3137 and returns 1 if successful else 0. 3138 3139 See descriptions of tunable parameters above. 3140 3141*/ 3142 3143#if __STD_C 3144int mALLOPt(int param_number, int value) 3145#else 3146int mALLOPt(param_number, value) int param_number; int value; 3147#endif 3148{ 3149 switch(param_number) 3150 { 3151 case M_TRIM_THRESHOLD: 3152 trim_threshold = value; return 1; 3153 case M_TOP_PAD: 3154 top_pad = value; return 1; 3155 case M_MMAP_THRESHOLD: 3156 mmap_threshold = value; return 1; 3157 case M_MMAP_MAX: 3158#if HAVE_MMAP 3159 n_mmaps_max = value; return 1; 3160#else 3161 if (value != 0) return 0; else n_mmaps_max = value; return 1; 3162#endif 3163 3164 default: 3165 return 0; 3166 } 3167} 3168 3169/* 3170 3171History: 3172 3173 V2.6.6 Sun Dec 5 07:42:19 1999 Doug Lea (dl at gee) 3174 * return null for negative arguments 3175 * Added Several WIN32 cleanups from Martin C. Fong <mcfong@yahoo.com> 3176 * Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h' 3177 (e.g. WIN32 platforms) 3178 * Cleanup up header file inclusion for WIN32 platforms 3179 * Cleanup code to avoid Microsoft Visual C++ compiler complaints 3180 * Add 'USE_DL_PREFIX' to quickly allow co-existence with existing 3181 memory allocation routines 3182 * Set 'malloc_getpagesize' for WIN32 platforms (needs more work) 3183 * Use 'assert' rather than 'ASSERT' in WIN32 code to conform to 3184 usage of 'assert' in non-WIN32 code 3185 * Improve WIN32 'sbrk()' emulation's 'findRegion()' routine to 3186 avoid infinite loop 3187 * Always call 'fREe()' rather than 'free()' 3188 3189 V2.6.5 Wed Jun 17 15:57:31 1998 Doug Lea (dl at gee) 3190 * Fixed ordering problem with boundary-stamping 3191 3192 V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee) 3193 * Added pvalloc, as recommended by H.J. Liu 3194 * Added 64bit pointer support mainly from Wolfram Gloger 3195 * Added anonymously donated WIN32 sbrk emulation 3196 * Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen 3197 * malloc_extend_top: fix mask error that caused wastage after 3198 foreign sbrks 3199 * Add linux mremap support code from HJ Liu 3200 3201 V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee) 3202 * Integrated most documentation with the code. 3203 * Add support for mmap, with help from 3204 Wolfram Gloger (Gloger@lrz.uni-muenchen.de). 3205 * Use last_remainder in more cases. 3206 * Pack bins using idea from colin@nyx10.cs.du.edu 3207 * Use ordered bins instead of best-fit threshhold 3208 * Eliminate block-local decls to simplify tracing and debugging. 3209 * Support another case of realloc via move into top 3210 * Fix error occuring when initial sbrk_base not word-aligned. 3211 * Rely on page size for units instead of SBRK_UNIT to 3212 avoid surprises about sbrk alignment conventions. 3213 * Add mallinfo, mallopt. Thanks to Raymond Nijssen 3214 (raymond@es.ele.tue.nl) for the suggestion. 3215 * Add `pad' argument to malloc_trim and top_pad mallopt parameter. 3216 * More precautions for cases where other routines call sbrk, 3217 courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de). 3218 * Added macros etc., allowing use in linux libc from 3219 H.J. Lu (hjl@gnu.ai.mit.edu) 3220 * Inverted this history list 3221 3222 V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee) 3223 * Re-tuned and fixed to behave more nicely with V2.6.0 changes. 3224 * Removed all preallocation code since under current scheme 3225 the work required to undo bad preallocations exceeds 3226 the work saved in good cases for most test programs. 3227 * No longer use return list or unconsolidated bins since 3228 no scheme using them consistently outperforms those that don't 3229 given above changes. 3230 * Use best fit for very large chunks to prevent some worst-cases. 3231 * Added some support for debugging 3232 3233 V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee) 3234 * Removed footers when chunks are in use. Thanks to 3235 Paul Wilson (wilson@cs.texas.edu) for the suggestion. 3236 3237 V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee) 3238 * Added malloc_trim, with help from Wolfram Gloger 3239 (wmglo@Dent.MED.Uni-Muenchen.DE). 3240 3241 V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g) 3242 3243 V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g) 3244 * realloc: try to expand in both directions 3245 * malloc: swap order of clean-bin strategy; 3246 * realloc: only conditionally expand backwards 3247 * Try not to scavenge used bins 3248 * Use bin counts as a guide to preallocation 3249 * Occasionally bin return list chunks in first scan 3250 * Add a few optimizations from colin@nyx10.cs.du.edu 3251 3252 V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g) 3253 * faster bin computation & slightly different binning 3254 * merged all consolidations to one part of malloc proper 3255 (eliminating old malloc_find_space & malloc_clean_bin) 3256 * Scan 2 returns chunks (not just 1) 3257 * Propagate failure in realloc if malloc returns 0 3258 * Add stuff to allow compilation on non-ANSI compilers 3259 from kpv@research.att.com 3260 3261 V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu) 3262 * removed potential for odd address access in prev_chunk 3263 * removed dependency on getpagesize.h 3264 * misc cosmetics and a bit more internal documentation 3265 * anticosmetics: mangled names in macros to evade debugger strangeness 3266 * tested on sparc, hp-700, dec-mips, rs6000 3267 with gcc & native cc (hp, dec only) allowing 3268 Detlefs & Zorn comparison study (in SIGPLAN Notices.) 3269 3270 Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu) 3271 * Based loosely on libg++-1.2X malloc. (It retains some of the overall 3272 structure of old version, but most details differ.) 3273 3274*/ 3275 3276 3277