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