1 #if 0 /* Moved to malloc.h */ 2 /* ---------- To make a malloc.h, start cutting here ------------ */ 3 4 /* 5 A version of malloc/free/realloc written by Doug Lea and released to the 6 public domain. Send questions/comments/complaints/performance data 7 to dl@cs.oswego.edu 8 9 * VERSION 2.6.6 Sun Mar 5 19:10:03 2000 Doug Lea (dl at gee) 10 11 Note: There may be an updated version of this malloc obtainable at 12 ftp://g.oswego.edu/pub/misc/malloc.c 13 Check before installing! 14 15 * Why use this malloc? 16 17 This is not the fastest, most space-conserving, most portable, or 18 most tunable malloc ever written. However it is among the fastest 19 while also being among the most space-conserving, portable and tunable. 20 Consistent balance across these factors results in a good general-purpose 21 allocator. For a high-level description, see 22 http://g.oswego.edu/dl/html/malloc.html 23 24 * Synopsis of public routines 25 26 (Much fuller descriptions are contained in the program documentation below.) 27 28 malloc(size_t n); 29 Return a pointer to a newly allocated chunk of at least n bytes, or null 30 if no space is available. 31 free(Void_t* p); 32 Release the chunk of memory pointed to by p, or no effect if p is null. 33 realloc(Void_t* p, size_t n); 34 Return a pointer to a chunk of size n that contains the same data 35 as does chunk p up to the minimum of (n, p's size) bytes, or null 36 if no space is available. The returned pointer may or may not be 37 the same as p. If p is null, equivalent to malloc. Unless the 38 #define REALLOC_ZERO_BYTES_FREES below is set, realloc with a 39 size argument of zero (re)allocates a minimum-sized chunk. 40 memalign(size_t alignment, size_t n); 41 Return a pointer to a newly allocated chunk of n bytes, aligned 42 in accord with the alignment argument, which must be a power of 43 two. 44 valloc(size_t n); 45 Equivalent to memalign(pagesize, n), where pagesize is the page 46 size of the system (or as near to this as can be figured out from 47 all the includes/defines below.) 48 pvalloc(size_t n); 49 Equivalent to valloc(minimum-page-that-holds(n)), that is, 50 round up n to nearest pagesize. 51 calloc(size_t unit, size_t quantity); 52 Returns a pointer to quantity * unit bytes, with all locations 53 set to zero. 54 cfree(Void_t* p); 55 Equivalent to free(p). 56 malloc_trim(size_t pad); 57 Release all but pad bytes of freed top-most memory back 58 to the system. Return 1 if successful, else 0. 59 malloc_usable_size(Void_t* p); 60 Report the number usable allocated bytes associated with allocated 61 chunk p. This may or may not report more bytes than were requested, 62 due to alignment and minimum size constraints. 63 malloc_stats(); 64 Prints brief summary statistics. 65 mallinfo() 66 Returns (by copy) a struct containing various summary statistics. 67 mallopt(int parameter_number, int parameter_value) 68 Changes one of the tunable parameters described below. Returns 69 1 if successful in changing the parameter, else 0. 70 71 * Vital statistics: 72 73 Alignment: 8-byte 74 8 byte alignment is currently hardwired into the design. This 75 seems to suffice for all current machines and C compilers. 76 77 Assumed pointer representation: 4 or 8 bytes 78 Code for 8-byte pointers is untested by me but has worked 79 reliably by Wolfram Gloger, who contributed most of the 80 changes supporting this. 81 82 Assumed size_t representation: 4 or 8 bytes 83 Note that size_t is allowed to be 4 bytes even if pointers are 8. 84 85 Minimum overhead per allocated chunk: 4 or 8 bytes 86 Each malloced chunk has a hidden overhead of 4 bytes holding size 87 and status information. 88 89 Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead) 90 8-byte ptrs: 24/32 bytes (including, 4/8 overhead) 91 92 When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte 93 ptrs but 4 byte size) or 24 (for 8/8) additional bytes are 94 needed; 4 (8) for a trailing size field 95 and 8 (16) bytes for free list pointers. Thus, the minimum 96 allocatable size is 16/24/32 bytes. 97 98 Even a request for zero bytes (i.e., malloc(0)) returns a 99 pointer to something of the minimum allocatable size. 100 101 Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes 102 8-byte size_t: 2^63 - 16 bytes 103 104 It is assumed that (possibly signed) size_t bit values suffice to 105 represent chunk sizes. `Possibly signed' is due to the fact 106 that `size_t' may be defined on a system as either a signed or 107 an unsigned type. To be conservative, values that would appear 108 as negative numbers are avoided. 109 Requests for sizes with a negative sign bit when the request 110 size is treaded as a long will return null. 111 112 Maximum overhead wastage per allocated chunk: normally 15 bytes 113 114 Alignnment demands, plus the minimum allocatable size restriction 115 make the normal worst-case wastage 15 bytes (i.e., up to 15 116 more bytes will be allocated than were requested in malloc), with 117 two exceptions: 118 1. Because requests for zero bytes allocate non-zero space, 119 the worst case wastage for a request of zero bytes is 24 bytes. 120 2. For requests >= mmap_threshold that are serviced via 121 mmap(), the worst case wastage is 8 bytes plus the remainder 122 from a system page (the minimal mmap unit); typically 4096 bytes. 123 124 * Limitations 125 126 Here are some features that are NOT currently supported 127 128 * No user-definable hooks for callbacks and the like. 129 * No automated mechanism for fully checking that all accesses 130 to malloced memory stay within their bounds. 131 * No support for compaction. 132 133 * Synopsis of compile-time options: 134 135 People have reported using previous versions of this malloc on all 136 versions of Unix, sometimes by tweaking some of the defines 137 below. It has been tested most extensively on Solaris and 138 Linux. It is also reported to work on WIN32 platforms. 139 People have also reported adapting this malloc for use in 140 stand-alone embedded systems. 141 142 The implementation is in straight, hand-tuned ANSI C. Among other 143 consequences, it uses a lot of macros. Because of this, to be at 144 all usable, this code should be compiled using an optimizing compiler 145 (for example gcc -O2) that can simplify expressions and control 146 paths. 147 148 __STD_C (default: derived from C compiler defines) 149 Nonzero if using ANSI-standard C compiler, a C++ compiler, or 150 a C compiler sufficiently close to ANSI to get away with it. 151 DEBUG (default: NOT defined) 152 Define to enable debugging. Adds fairly extensive assertion-based 153 checking to help track down memory errors, but noticeably slows down 154 execution. 155 REALLOC_ZERO_BYTES_FREES (default: NOT defined) 156 Define this if you think that realloc(p, 0) should be equivalent 157 to free(p). Otherwise, since malloc returns a unique pointer for 158 malloc(0), so does realloc(p, 0). 159 HAVE_MEMCPY (default: defined) 160 Define if you are not otherwise using ANSI STD C, but still 161 have memcpy and memset in your C library and want to use them. 162 Otherwise, simple internal versions are supplied. 163 USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise) 164 Define as 1 if you want the C library versions of memset and 165 memcpy called in realloc and calloc (otherwise macro versions are used). 166 At least on some platforms, the simple macro versions usually 167 outperform libc versions. 168 HAVE_MMAP (default: defined as 1) 169 Define to non-zero to optionally make malloc() use mmap() to 170 allocate very large blocks. 171 HAVE_MREMAP (default: defined as 0 unless Linux libc set) 172 Define to non-zero to optionally make realloc() use mremap() to 173 reallocate very large blocks. 174 malloc_getpagesize (default: derived from system #includes) 175 Either a constant or routine call returning the system page size. 176 HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined) 177 Optionally define if you are on a system with a /usr/include/malloc.h 178 that declares struct mallinfo. It is not at all necessary to 179 define this even if you do, but will ensure consistency. 180 INTERNAL_SIZE_T (default: size_t) 181 Define to a 32-bit type (probably `unsigned int') if you are on a 182 64-bit machine, yet do not want or need to allow malloc requests of 183 greater than 2^31 to be handled. This saves space, especially for 184 very small chunks. 185 INTERNAL_LINUX_C_LIB (default: NOT defined) 186 Defined only when compiled as part of Linux libc. 187 Also note that there is some odd internal name-mangling via defines 188 (for example, internally, `malloc' is named `mALLOc') needed 189 when compiling in this case. These look funny but don't otherwise 190 affect anything. 191 WIN32 (default: undefined) 192 Define this on MS win (95, nt) platforms to compile in sbrk emulation. 193 LACKS_UNISTD_H (default: undefined if not WIN32) 194 Define this if your system does not have a <unistd.h>. 195 LACKS_SYS_PARAM_H (default: undefined if not WIN32) 196 Define this if your system does not have a <sys/param.h>. 197 MORECORE (default: sbrk) 198 The name of the routine to call to obtain more memory from the system. 199 MORECORE_FAILURE (default: -1) 200 The value returned upon failure of MORECORE. 201 MORECORE_CLEARS (default 1) 202 True (1) if the routine mapped to MORECORE zeroes out memory (which 203 holds for sbrk). 204 DEFAULT_TRIM_THRESHOLD 205 DEFAULT_TOP_PAD 206 DEFAULT_MMAP_THRESHOLD 207 DEFAULT_MMAP_MAX 208 Default values of tunable parameters (described in detail below) 209 controlling interaction with host system routines (sbrk, mmap, etc). 210 These values may also be changed dynamically via mallopt(). The 211 preset defaults are those that give best performance for typical 212 programs/systems. 213 USE_DL_PREFIX (default: undefined) 214 Prefix all public routines with the string 'dl'. Useful to 215 quickly avoid procedure declaration conflicts and linker symbol 216 conflicts with existing memory allocation routines. 217 218 219 */ 220 221 222 223 224 /* Preliminaries */ 225 226 #ifndef __STD_C 227 #ifdef __STDC__ 228 #define __STD_C 1 229 #else 230 #if __cplusplus 231 #define __STD_C 1 232 #else 233 #define __STD_C 0 234 #endif /*__cplusplus*/ 235 #endif /*__STDC__*/ 236 #endif /*__STD_C*/ 237 238 #ifndef Void_t 239 #if (__STD_C || defined(WIN32)) 240 #define Void_t void 241 #else 242 #define Void_t char 243 #endif 244 #endif /*Void_t*/ 245 246 #if __STD_C 247 #include <stddef.h> /* for size_t */ 248 #else 249 #include <sys/types.h> 250 #endif 251 252 #ifdef __cplusplus 253 extern "C" { 254 #endif 255 256 #include <stdio.h> /* needed for malloc_stats */ 257 258 259 /* 260 Compile-time options 261 */ 262 263 264 /* 265 Debugging: 266 267 Because freed chunks may be overwritten with link fields, this 268 malloc will often die when freed memory is overwritten by user 269 programs. This can be very effective (albeit in an annoying way) 270 in helping track down dangling pointers. 271 272 If you compile with -DDEBUG, a number of assertion checks are 273 enabled that will catch more memory errors. You probably won't be 274 able to make much sense of the actual assertion errors, but they 275 should help you locate incorrectly overwritten memory. The 276 checking is fairly extensive, and will slow down execution 277 noticeably. Calling malloc_stats or mallinfo with DEBUG set will 278 attempt to check every non-mmapped allocated and free chunk in the 279 course of computing the summmaries. (By nature, mmapped regions 280 cannot be checked very much automatically.) 281 282 Setting DEBUG may also be helpful if you are trying to modify 283 this code. The assertions in the check routines spell out in more 284 detail the assumptions and invariants underlying the algorithms. 285 286 */ 287 288 #ifdef DEBUG 289 #include <assert.h> 290 #else 291 #define assert(x) ((void)0) 292 #endif 293 294 295 /* 296 INTERNAL_SIZE_T is the word-size used for internal bookkeeping 297 of chunk sizes. On a 64-bit machine, you can reduce malloc 298 overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int' 299 at the expense of not being able to handle requests greater than 300 2^31. This limitation is hardly ever a concern; you are encouraged 301 to set this. However, the default version is the same as size_t. 302 */ 303 304 #ifndef INTERNAL_SIZE_T 305 #define INTERNAL_SIZE_T size_t 306 #endif 307 308 /* 309 REALLOC_ZERO_BYTES_FREES should be set if a call to 310 realloc with zero bytes should be the same as a call to free. 311 Some people think it should. Otherwise, since this malloc 312 returns a unique pointer for malloc(0), so does realloc(p, 0). 313 */ 314 315 316 /* #define REALLOC_ZERO_BYTES_FREES */ 317 318 319 /* 320 WIN32 causes an emulation of sbrk to be compiled in 321 mmap-based options are not currently supported in WIN32. 322 */ 323 324 /* #define WIN32 */ 325 #ifdef WIN32 326 #define MORECORE wsbrk 327 #define HAVE_MMAP 0 328 329 #define LACKS_UNISTD_H 330 #define LACKS_SYS_PARAM_H 331 332 /* 333 Include 'windows.h' to get the necessary declarations for the 334 Microsoft Visual C++ data structures and routines used in the 'sbrk' 335 emulation. 336 337 Define WIN32_LEAN_AND_MEAN so that only the essential Microsoft 338 Visual C++ header files are included. 339 */ 340 #define WIN32_LEAN_AND_MEAN 341 #include <windows.h> 342 #endif 343 344 345 /* 346 HAVE_MEMCPY should be defined if you are not otherwise using 347 ANSI STD C, but still have memcpy and memset in your C library 348 and want to use them in calloc and realloc. Otherwise simple 349 macro versions are defined here. 350 351 USE_MEMCPY should be defined as 1 if you actually want to 352 have memset and memcpy called. People report that the macro 353 versions are often enough faster than libc versions on many 354 systems that it is better to use them. 355 356 */ 357 358 #define HAVE_MEMCPY 359 360 #ifndef USE_MEMCPY 361 #ifdef HAVE_MEMCPY 362 #define USE_MEMCPY 1 363 #else 364 #define USE_MEMCPY 0 365 #endif 366 #endif 367 368 #if (__STD_C || defined(HAVE_MEMCPY)) 369 370 #if __STD_C 371 void* memset(void*, int, size_t); 372 void* memcpy(void*, const void*, size_t); 373 #else 374 #ifdef WIN32 375 // On Win32 platforms, 'memset()' and 'memcpy()' are already declared in 376 // 'windows.h' 377 #else 378 Void_t* memset(); 379 Void_t* memcpy(); 380 #endif 381 #endif 382 #endif 383 384 #if USE_MEMCPY 385 386 /* The following macros are only invoked with (2n+1)-multiples of 387 INTERNAL_SIZE_T units, with a positive integer n. This is exploited 388 for fast inline execution when n is small. */ 389 390 #define MALLOC_ZERO(charp, nbytes) \ 391 do { \ 392 INTERNAL_SIZE_T mzsz = (nbytes); \ 393 if(mzsz <= 9*sizeof(mzsz)) { \ 394 INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \ 395 if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \ 396 *mz++ = 0; \ 397 if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \ 398 *mz++ = 0; \ 399 if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \ 400 *mz++ = 0; }}} \ 401 *mz++ = 0; \ 402 *mz++ = 0; \ 403 *mz = 0; \ 404 } else memset((charp), 0, mzsz); \ 405 } while(0) 406 407 #define MALLOC_COPY(dest,src,nbytes) \ 408 do { \ 409 INTERNAL_SIZE_T mcsz = (nbytes); \ 410 if(mcsz <= 9*sizeof(mcsz)) { \ 411 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \ 412 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \ 413 if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ 414 *mcdst++ = *mcsrc++; \ 415 if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ 416 *mcdst++ = *mcsrc++; \ 417 if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ 418 *mcdst++ = *mcsrc++; }}} \ 419 *mcdst++ = *mcsrc++; \ 420 *mcdst++ = *mcsrc++; \ 421 *mcdst = *mcsrc ; \ 422 } else memcpy(dest, src, mcsz); \ 423 } while(0) 424 425 #else /* !USE_MEMCPY */ 426 427 /* Use Duff's device for good zeroing/copying performance. */ 428 429 #define MALLOC_ZERO(charp, nbytes) \ 430 do { \ 431 INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \ 432 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \ 433 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \ 434 switch (mctmp) { \ 435 case 0: for(;;) { *mzp++ = 0; \ 436 case 7: *mzp++ = 0; \ 437 case 6: *mzp++ = 0; \ 438 case 5: *mzp++ = 0; \ 439 case 4: *mzp++ = 0; \ 440 case 3: *mzp++ = 0; \ 441 case 2: *mzp++ = 0; \ 442 case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \ 443 } \ 444 } while(0) 445 446 #define MALLOC_COPY(dest,src,nbytes) \ 447 do { \ 448 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \ 449 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \ 450 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \ 451 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \ 452 switch (mctmp) { \ 453 case 0: for(;;) { *mcdst++ = *mcsrc++; \ 454 case 7: *mcdst++ = *mcsrc++; \ 455 case 6: *mcdst++ = *mcsrc++; \ 456 case 5: *mcdst++ = *mcsrc++; \ 457 case 4: *mcdst++ = *mcsrc++; \ 458 case 3: *mcdst++ = *mcsrc++; \ 459 case 2: *mcdst++ = *mcsrc++; \ 460 case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \ 461 } \ 462 } while(0) 463 464 #endif 465 466 467 /* 468 Define HAVE_MMAP to optionally make malloc() use mmap() to 469 allocate very large blocks. These will be returned to the 470 operating system immediately after a free(). 471 */ 472 473 #ifndef HAVE_MMAP 474 #define HAVE_MMAP 1 475 #endif 476 477 /* 478 Define HAVE_MREMAP to make realloc() use mremap() to re-allocate 479 large blocks. This is currently only possible on Linux with 480 kernel versions newer than 1.3.77. 481 */ 482 483 #ifndef HAVE_MREMAP 484 #ifdef INTERNAL_LINUX_C_LIB 485 #define HAVE_MREMAP 1 486 #else 487 #define HAVE_MREMAP 0 488 #endif 489 #endif 490 491 #if HAVE_MMAP 492 493 #include <unistd.h> 494 #include <fcntl.h> 495 #include <sys/mman.h> 496 497 #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON) 498 #define MAP_ANONYMOUS MAP_ANON 499 #endif 500 501 #endif /* HAVE_MMAP */ 502 503 /* 504 Access to system page size. To the extent possible, this malloc 505 manages memory from the system in page-size units. 506 507 The following mechanics for getpagesize were adapted from 508 bsd/gnu getpagesize.h 509 */ 510 511 #ifndef LACKS_UNISTD_H 512 # include <unistd.h> 513 #endif 514 515 #ifndef malloc_getpagesize 516 # ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */ 517 # ifndef _SC_PAGE_SIZE 518 # define _SC_PAGE_SIZE _SC_PAGESIZE 519 # endif 520 # endif 521 # ifdef _SC_PAGE_SIZE 522 # define malloc_getpagesize sysconf(_SC_PAGE_SIZE) 523 # else 524 # if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE) 525 extern size_t getpagesize(); 526 # define malloc_getpagesize getpagesize() 527 # else 528 # ifdef WIN32 529 # define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */ 530 # else 531 # ifndef LACKS_SYS_PARAM_H 532 # include <sys/param.h> 533 # endif 534 # ifdef EXEC_PAGESIZE 535 # define malloc_getpagesize EXEC_PAGESIZE 536 # else 537 # ifdef NBPG 538 # ifndef CLSIZE 539 # define malloc_getpagesize NBPG 540 # else 541 # define malloc_getpagesize (NBPG * CLSIZE) 542 # endif 543 # else 544 # ifdef NBPC 545 # define malloc_getpagesize NBPC 546 # else 547 # ifdef PAGESIZE 548 # define malloc_getpagesize PAGESIZE 549 # else 550 # define malloc_getpagesize (4096) /* just guess */ 551 # endif 552 # endif 553 # endif 554 # endif 555 # endif 556 # endif 557 # endif 558 #endif 559 560 561 562 /* 563 564 This version of malloc supports the standard SVID/XPG mallinfo 565 routine that returns a struct containing the same kind of 566 information you can get from malloc_stats. It should work on 567 any SVID/XPG compliant system that has a /usr/include/malloc.h 568 defining struct mallinfo. (If you'd like to install such a thing 569 yourself, cut out the preliminary declarations as described above 570 and below and save them in a malloc.h file. But there's no 571 compelling reason to bother to do this.) 572 573 The main declaration needed is the mallinfo struct that is returned 574 (by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a 575 bunch of fields, most of which are not even meaningful in this 576 version of malloc. Some of these fields are are instead filled by 577 mallinfo() with other numbers that might possibly be of interest. 578 579 HAVE_USR_INCLUDE_MALLOC_H should be set if you have a 580 /usr/include/malloc.h file that includes a declaration of struct 581 mallinfo. If so, it is included; else an SVID2/XPG2 compliant 582 version is declared below. These must be precisely the same for 583 mallinfo() to work. 584 585 */ 586 587 /* #define HAVE_USR_INCLUDE_MALLOC_H */ 588 589 #if HAVE_USR_INCLUDE_MALLOC_H 590 #include "/usr/include/malloc.h" 591 #else 592 593 /* SVID2/XPG mallinfo structure */ 594 595 struct mallinfo { 596 int arena; /* total space allocated from system */ 597 int ordblks; /* number of non-inuse chunks */ 598 int smblks; /* unused -- always zero */ 599 int hblks; /* number of mmapped regions */ 600 int hblkhd; /* total space in mmapped regions */ 601 int usmblks; /* unused -- always zero */ 602 int fsmblks; /* unused -- always zero */ 603 int uordblks; /* total allocated space */ 604 int fordblks; /* total non-inuse space */ 605 int keepcost; /* top-most, releasable (via malloc_trim) space */ 606 }; 607 608 /* SVID2/XPG mallopt options */ 609 610 #define M_MXFAST 1 /* UNUSED in this malloc */ 611 #define M_NLBLKS 2 /* UNUSED in this malloc */ 612 #define M_GRAIN 3 /* UNUSED in this malloc */ 613 #define M_KEEP 4 /* UNUSED in this malloc */ 614 615 #endif 616 617 /* mallopt options that actually do something */ 618 619 #define M_TRIM_THRESHOLD -1 620 #define M_TOP_PAD -2 621 #define M_MMAP_THRESHOLD -3 622 #define M_MMAP_MAX -4 623 624 625 626 #ifndef DEFAULT_TRIM_THRESHOLD 627 #define DEFAULT_TRIM_THRESHOLD (128 * 1024) 628 #endif 629 630 /* 631 M_TRIM_THRESHOLD is the maximum amount of unused top-most memory 632 to keep before releasing via malloc_trim in free(). 633 634 Automatic trimming is mainly useful in long-lived programs. 635 Because trimming via sbrk can be slow on some systems, and can 636 sometimes be wasteful (in cases where programs immediately 637 afterward allocate more large chunks) the value should be high 638 enough so that your overall system performance would improve by 639 releasing. 640 641 The trim threshold and the mmap control parameters (see below) 642 can be traded off with one another. Trimming and mmapping are 643 two different ways of releasing unused memory back to the 644 system. Between these two, it is often possible to keep 645 system-level demands of a long-lived program down to a bare 646 minimum. For example, in one test suite of sessions measuring 647 the XF86 X server on Linux, using a trim threshold of 128K and a 648 mmap threshold of 192K led to near-minimal long term resource 649 consumption. 650 651 If you are using this malloc in a long-lived program, it should 652 pay to experiment with these values. As a rough guide, you 653 might set to a value close to the average size of a process 654 (program) running on your system. Releasing this much memory 655 would allow such a process to run in memory. Generally, it's 656 worth it to tune for trimming rather tham memory mapping when a 657 program undergoes phases where several large chunks are 658 allocated and released in ways that can reuse each other's 659 storage, perhaps mixed with phases where there are no such 660 chunks at all. And in well-behaved long-lived programs, 661 controlling release of large blocks via trimming versus mapping 662 is usually faster. 663 664 However, in most programs, these parameters serve mainly as 665 protection against the system-level effects of carrying around 666 massive amounts of unneeded memory. Since frequent calls to 667 sbrk, mmap, and munmap otherwise degrade performance, the default 668 parameters are set to relatively high values that serve only as 669 safeguards. 670 671 The default trim value is high enough to cause trimming only in 672 fairly extreme (by current memory consumption standards) cases. 673 It must be greater than page size to have any useful effect. To 674 disable trimming completely, you can set to (unsigned long)(-1); 675 676 677 */ 678 679 680 #ifndef DEFAULT_TOP_PAD 681 #define DEFAULT_TOP_PAD (0) 682 #endif 683 684 /* 685 M_TOP_PAD is the amount of extra `padding' space to allocate or 686 retain whenever sbrk is called. It is used in two ways internally: 687 688 * When sbrk is called to extend the top of the arena to satisfy 689 a new malloc request, this much padding is added to the sbrk 690 request. 691 692 * When malloc_trim is called automatically from free(), 693 it is used as the `pad' argument. 694 695 In both cases, the actual amount of padding is rounded 696 so that the end of the arena is always a system page boundary. 697 698 The main reason for using padding is to avoid calling sbrk so 699 often. Having even a small pad greatly reduces the likelihood 700 that nearly every malloc request during program start-up (or 701 after trimming) will invoke sbrk, which needlessly wastes 702 time. 703 704 Automatic rounding-up to page-size units is normally sufficient 705 to avoid measurable overhead, so the default is 0. However, in 706 systems where sbrk is relatively slow, it can pay to increase 707 this value, at the expense of carrying around more memory than 708 the program needs. 709 710 */ 711 712 713 #ifndef DEFAULT_MMAP_THRESHOLD 714 #define DEFAULT_MMAP_THRESHOLD (128 * 1024) 715 #endif 716 717 /* 718 719 M_MMAP_THRESHOLD is the request size threshold for using mmap() 720 to service a request. Requests of at least this size that cannot 721 be allocated using already-existing space will be serviced via mmap. 722 (If enough normal freed space already exists it is used instead.) 723 724 Using mmap segregates relatively large chunks of memory so that 725 they can be individually obtained and released from the host 726 system. A request serviced through mmap is never reused by any 727 other request (at least not directly; the system may just so 728 happen to remap successive requests to the same locations). 729 730 Segregating space in this way has the benefit that mmapped space 731 can ALWAYS be individually released back to the system, which 732 helps keep the system level memory demands of a long-lived 733 program low. Mapped memory can never become `locked' between 734 other chunks, as can happen with normally allocated chunks, which 735 menas that even trimming via malloc_trim would not release them. 736 737 However, it has the disadvantages that: 738 739 1. The space cannot be reclaimed, consolidated, and then 740 used to service later requests, as happens with normal chunks. 741 2. It can lead to more wastage because of mmap page alignment 742 requirements 743 3. It causes malloc performance to be more dependent on host 744 system memory management support routines which may vary in 745 implementation quality and may impose arbitrary 746 limitations. Generally, servicing a request via normal 747 malloc steps is faster than going through a system's mmap. 748 749 All together, these considerations should lead you to use mmap 750 only for relatively large requests. 751 752 753 */ 754 755 756 757 #ifndef DEFAULT_MMAP_MAX 758 #if HAVE_MMAP 759 #define DEFAULT_MMAP_MAX (64) 760 #else 761 #define DEFAULT_MMAP_MAX (0) 762 #endif 763 #endif 764 765 /* 766 M_MMAP_MAX is the maximum number of requests to simultaneously 767 service using mmap. This parameter exists because: 768 769 1. Some systems have a limited number of internal tables for 770 use by mmap. 771 2. In most systems, overreliance on mmap can degrade overall 772 performance. 773 3. If a program allocates many large regions, it is probably 774 better off using normal sbrk-based allocation routines that 775 can reclaim and reallocate normal heap memory. Using a 776 small value allows transition into this mode after the 777 first few allocations. 778 779 Setting to 0 disables all use of mmap. If HAVE_MMAP is not set, 780 the default value is 0, and attempts to set it to non-zero values 781 in mallopt will fail. 782 */ 783 784 785 786 787 /* 788 USE_DL_PREFIX will prefix all public routines with the string 'dl'. 789 Useful to quickly avoid procedure declaration conflicts and linker 790 symbol conflicts with existing memory allocation routines. 791 792 */ 793 794 /* #define USE_DL_PREFIX */ 795 796 797 798 799 /* 800 801 Special defines for linux libc 802 803 Except when compiled using these special defines for Linux libc 804 using weak aliases, this malloc is NOT designed to work in 805 multithreaded applications. No semaphores or other concurrency 806 control are provided to ensure that multiple malloc or free calls 807 don't run at the same time, which could be disasterous. A single 808 semaphore could be used across malloc, realloc, and free (which is 809 essentially the effect of the linux weak alias approach). It would 810 be hard to obtain finer granularity. 811 812 */ 813 814 815 #ifdef INTERNAL_LINUX_C_LIB 816 817 #if __STD_C 818 819 Void_t * __default_morecore_init (ptrdiff_t); 820 Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init; 821 822 #else 823 824 Void_t * __default_morecore_init (); 825 Void_t *(*__morecore)() = __default_morecore_init; 826 827 #endif 828 829 #define MORECORE (*__morecore) 830 #define MORECORE_FAILURE 0 831 #define MORECORE_CLEARS 1 832 833 #else /* INTERNAL_LINUX_C_LIB */ 834 835 #if __STD_C 836 extern Void_t* sbrk(ptrdiff_t); 837 #else 838 extern Void_t* sbrk(); 839 #endif 840 841 #ifndef MORECORE 842 #define MORECORE sbrk 843 #endif 844 845 #ifndef MORECORE_FAILURE 846 #define MORECORE_FAILURE -1 847 #endif 848 849 #ifndef MORECORE_CLEARS 850 #define MORECORE_CLEARS 1 851 #endif 852 853 #endif /* INTERNAL_LINUX_C_LIB */ 854 855 #if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__) 856 857 #define cALLOc __libc_calloc 858 #define fREe __libc_free 859 #define mALLOc __libc_malloc 860 #define mEMALIGn __libc_memalign 861 #define rEALLOc __libc_realloc 862 #define vALLOc __libc_valloc 863 #define pvALLOc __libc_pvalloc 864 #define mALLINFo __libc_mallinfo 865 #define mALLOPt __libc_mallopt 866 867 #pragma weak calloc = __libc_calloc 868 #pragma weak free = __libc_free 869 #pragma weak cfree = __libc_free 870 #pragma weak malloc = __libc_malloc 871 #pragma weak memalign = __libc_memalign 872 #pragma weak realloc = __libc_realloc 873 #pragma weak valloc = __libc_valloc 874 #pragma weak pvalloc = __libc_pvalloc 875 #pragma weak mallinfo = __libc_mallinfo 876 #pragma weak mallopt = __libc_mallopt 877 878 #else 879 880 #ifdef USE_DL_PREFIX 881 #define cALLOc dlcalloc 882 #define fREe dlfree 883 #define mALLOc dlmalloc 884 #define mEMALIGn dlmemalign 885 #define rEALLOc dlrealloc 886 #define vALLOc dlvalloc 887 #define pvALLOc dlpvalloc 888 #define mALLINFo dlmallinfo 889 #define mALLOPt dlmallopt 890 #else /* USE_DL_PREFIX */ 891 #define cALLOc calloc 892 #define fREe free 893 #define mALLOc malloc 894 #define mEMALIGn memalign 895 #define rEALLOc realloc 896 #define vALLOc valloc 897 #define pvALLOc pvalloc 898 #define mALLINFo mallinfo 899 #define mALLOPt mallopt 900 #endif /* USE_DL_PREFIX */ 901 902 #endif 903 904 /* Public routines */ 905 906 #if __STD_C 907 908 Void_t* mALLOc(size_t); 909 void fREe(Void_t*); 910 Void_t* rEALLOc(Void_t*, size_t); 911 Void_t* mEMALIGn(size_t, size_t); 912 Void_t* vALLOc(size_t); 913 Void_t* pvALLOc(size_t); 914 Void_t* cALLOc(size_t, size_t); 915 void cfree(Void_t*); 916 int malloc_trim(size_t); 917 size_t malloc_usable_size(Void_t*); 918 void malloc_stats(); 919 int mALLOPt(int, int); 920 struct mallinfo mALLINFo(void); 921 #else 922 Void_t* mALLOc(); 923 void fREe(); 924 Void_t* rEALLOc(); 925 Void_t* mEMALIGn(); 926 Void_t* vALLOc(); 927 Void_t* pvALLOc(); 928 Void_t* cALLOc(); 929 void cfree(); 930 int malloc_trim(); 931 size_t malloc_usable_size(); 932 void malloc_stats(); 933 int mALLOPt(); 934 struct mallinfo mALLINFo(); 935 #endif 936 937 938 #ifdef __cplusplus 939 }; /* end of extern "C" */ 940 #endif 941 942 /* ---------- To make a malloc.h, end cutting here ------------ */ 943 #else /* Moved to malloc.h */ 944 945 #include <malloc.h> 946 #if 0 947 #if __STD_C 948 static void malloc_update_mallinfo (void); 949 void malloc_stats (void); 950 #else 951 static void malloc_update_mallinfo (); 952 void malloc_stats(); 953 #endif 954 #endif /* 0 */ 955 956 #endif /* 0 */ /* Moved to malloc.h */ 957 #include <common.h> 958 959 /* 960 Emulation of sbrk for WIN32 961 All code within the ifdef WIN32 is untested by me. 962 963 Thanks to Martin Fong and others for supplying this. 964 */ 965 966 967 #ifdef WIN32 968 969 #define AlignPage(add) (((add) + (malloc_getpagesize-1)) & \ 970 ~(malloc_getpagesize-1)) 971 #define AlignPage64K(add) (((add) + (0x10000 - 1)) & ~(0x10000 - 1)) 972 973 /* resrve 64MB to insure large contiguous space */ 974 #define RESERVED_SIZE (1024*1024*64) 975 #define NEXT_SIZE (2048*1024) 976 #define TOP_MEMORY ((unsigned long)2*1024*1024*1024) 977 978 struct GmListElement; 979 typedef struct GmListElement GmListElement; 980 981 struct GmListElement 982 { 983 GmListElement* next; 984 void* base; 985 }; 986 987 static GmListElement* head = 0; 988 static unsigned int gNextAddress = 0; 989 static unsigned int gAddressBase = 0; 990 static unsigned int gAllocatedSize = 0; 991 992 static 993 GmListElement* makeGmListElement (void* bas) 994 { 995 GmListElement* this; 996 this = (GmListElement*)(void*)LocalAlloc (0, sizeof (GmListElement)); 997 assert (this); 998 if (this) 999 { 1000 this->base = bas; 1001 this->next = head; 1002 head = this; 1003 } 1004 return this; 1005 } 1006 1007 void gcleanup () 1008 { 1009 BOOL rval; 1010 assert ( (head == NULL) || (head->base == (void*)gAddressBase)); 1011 if (gAddressBase && (gNextAddress - gAddressBase)) 1012 { 1013 rval = VirtualFree ((void*)gAddressBase, 1014 gNextAddress - gAddressBase, 1015 MEM_DECOMMIT); 1016 assert (rval); 1017 } 1018 while (head) 1019 { 1020 GmListElement* next = head->next; 1021 rval = VirtualFree (head->base, 0, MEM_RELEASE); 1022 assert (rval); 1023 LocalFree (head); 1024 head = next; 1025 } 1026 } 1027 1028 static 1029 void* findRegion (void* start_address, unsigned long size) 1030 { 1031 MEMORY_BASIC_INFORMATION info; 1032 if (size >= TOP_MEMORY) return NULL; 1033 1034 while ((unsigned long)start_address + size < TOP_MEMORY) 1035 { 1036 VirtualQuery (start_address, &info, sizeof (info)); 1037 if ((info.State == MEM_FREE) && (info.RegionSize >= size)) 1038 return start_address; 1039 else 1040 { 1041 // Requested region is not available so see if the 1042 // next region is available. Set 'start_address' 1043 // to the next region and call 'VirtualQuery()' 1044 // again. 1045 1046 start_address = (char*)info.BaseAddress + info.RegionSize; 1047 1048 // Make sure we start looking for the next region 1049 // on the *next* 64K boundary. Otherwise, even if 1050 // the new region is free according to 1051 // 'VirtualQuery()', the subsequent call to 1052 // 'VirtualAlloc()' (which follows the call to 1053 // this routine in 'wsbrk()') will round *down* 1054 // the requested address to a 64K boundary which 1055 // we already know is an address in the 1056 // unavailable region. Thus, the subsequent call 1057 // to 'VirtualAlloc()' will fail and bring us back 1058 // here, causing us to go into an infinite loop. 1059 1060 start_address = 1061 (void *) AlignPage64K((unsigned long) start_address); 1062 } 1063 } 1064 return NULL; 1065 1066 } 1067 1068 1069 void* wsbrk (long size) 1070 { 1071 void* tmp; 1072 if (size > 0) 1073 { 1074 if (gAddressBase == 0) 1075 { 1076 gAllocatedSize = max (RESERVED_SIZE, AlignPage (size)); 1077 gNextAddress = gAddressBase = 1078 (unsigned int)VirtualAlloc (NULL, gAllocatedSize, 1079 MEM_RESERVE, PAGE_NOACCESS); 1080 } else if (AlignPage (gNextAddress + size) > (gAddressBase + 1081 gAllocatedSize)) 1082 { 1083 long new_size = max (NEXT_SIZE, AlignPage (size)); 1084 void* new_address = (void*)(gAddressBase+gAllocatedSize); 1085 do 1086 { 1087 new_address = findRegion (new_address, new_size); 1088 1089 if (new_address == 0) 1090 return (void*)-1; 1091 1092 gAddressBase = gNextAddress = 1093 (unsigned int)VirtualAlloc (new_address, new_size, 1094 MEM_RESERVE, PAGE_NOACCESS); 1095 // repeat in case of race condition 1096 // The region that we found has been snagged 1097 // by another thread 1098 } 1099 while (gAddressBase == 0); 1100 1101 assert (new_address == (void*)gAddressBase); 1102 1103 gAllocatedSize = new_size; 1104 1105 if (!makeGmListElement ((void*)gAddressBase)) 1106 return (void*)-1; 1107 } 1108 if ((size + gNextAddress) > AlignPage (gNextAddress)) 1109 { 1110 void* res; 1111 res = VirtualAlloc ((void*)AlignPage (gNextAddress), 1112 (size + gNextAddress - 1113 AlignPage (gNextAddress)), 1114 MEM_COMMIT, PAGE_READWRITE); 1115 if (res == 0) 1116 return (void*)-1; 1117 } 1118 tmp = (void*)gNextAddress; 1119 gNextAddress = (unsigned int)tmp + size; 1120 return tmp; 1121 } 1122 else if (size < 0) 1123 { 1124 unsigned int alignedGoal = AlignPage (gNextAddress + size); 1125 /* Trim by releasing the virtual memory */ 1126 if (alignedGoal >= gAddressBase) 1127 { 1128 VirtualFree ((void*)alignedGoal, gNextAddress - alignedGoal, 1129 MEM_DECOMMIT); 1130 gNextAddress = gNextAddress + size; 1131 return (void*)gNextAddress; 1132 } 1133 else 1134 { 1135 VirtualFree ((void*)gAddressBase, gNextAddress - gAddressBase, 1136 MEM_DECOMMIT); 1137 gNextAddress = gAddressBase; 1138 return (void*)-1; 1139 } 1140 } 1141 else 1142 { 1143 return (void*)gNextAddress; 1144 } 1145 } 1146 1147 #endif 1148 1149 1150 1151 /* 1152 Type declarations 1153 */ 1154 1155 1156 struct malloc_chunk 1157 { 1158 INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */ 1159 INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */ 1160 struct malloc_chunk* fd; /* double links -- used only if free. */ 1161 struct malloc_chunk* bk; 1162 }; 1163 1164 typedef struct malloc_chunk* mchunkptr; 1165 1166 /* 1167 1168 malloc_chunk details: 1169 1170 (The following includes lightly edited explanations by Colin Plumb.) 1171 1172 Chunks of memory are maintained using a `boundary tag' method as 1173 described in e.g., Knuth or Standish. (See the paper by Paul 1174 Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a 1175 survey of such techniques.) Sizes of free chunks are stored both 1176 in the front of each chunk and at the end. This makes 1177 consolidating fragmented chunks into bigger chunks very fast. The 1178 size fields also hold bits representing whether chunks are free or 1179 in use. 1180 1181 An allocated chunk looks like this: 1182 1183 1184 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1185 | Size of previous chunk, if allocated | | 1186 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1187 | Size of chunk, in bytes |P| 1188 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1189 | User data starts here... . 1190 . . 1191 . (malloc_usable_space() bytes) . 1192 . | 1193 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1194 | Size of chunk | 1195 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1196 1197 1198 Where "chunk" is the front of the chunk for the purpose of most of 1199 the malloc code, but "mem" is the pointer that is returned to the 1200 user. "Nextchunk" is the beginning of the next contiguous chunk. 1201 1202 Chunks always begin on even word boundries, so the mem portion 1203 (which is returned to the user) is also on an even word boundary, and 1204 thus double-word aligned. 1205 1206 Free chunks are stored in circular doubly-linked lists, and look like this: 1207 1208 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1209 | Size of previous chunk | 1210 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1211 `head:' | Size of chunk, in bytes |P| 1212 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1213 | Forward pointer to next chunk in list | 1214 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1215 | Back pointer to previous chunk in list | 1216 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1217 | Unused space (may be 0 bytes long) . 1218 . . 1219 . | 1220 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1221 `foot:' | Size of chunk, in bytes | 1222 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1223 1224 The P (PREV_INUSE) bit, stored in the unused low-order bit of the 1225 chunk size (which is always a multiple of two words), is an in-use 1226 bit for the *previous* chunk. If that bit is *clear*, then the 1227 word before the current chunk size contains the previous chunk 1228 size, and can be used to find the front of the previous chunk. 1229 (The very first chunk allocated always has this bit set, 1230 preventing access to non-existent (or non-owned) memory.) 1231 1232 Note that the `foot' of the current chunk is actually represented 1233 as the prev_size of the NEXT chunk. (This makes it easier to 1234 deal with alignments etc). 1235 1236 The two exceptions to all this are 1237 1238 1. The special chunk `top', which doesn't bother using the 1239 trailing size field since there is no 1240 next contiguous chunk that would have to index off it. (After 1241 initialization, `top' is forced to always exist. If it would 1242 become less than MINSIZE bytes long, it is replenished via 1243 malloc_extend_top.) 1244 1245 2. Chunks allocated via mmap, which have the second-lowest-order 1246 bit (IS_MMAPPED) set in their size fields. Because they are 1247 never merged or traversed from any other chunk, they have no 1248 foot size or inuse information. 1249 1250 Available chunks are kept in any of several places (all declared below): 1251 1252 * `av': An array of chunks serving as bin headers for consolidated 1253 chunks. Each bin is doubly linked. The bins are approximately 1254 proportionally (log) spaced. There are a lot of these bins 1255 (128). This may look excessive, but works very well in 1256 practice. All procedures maintain the invariant that no 1257 consolidated chunk physically borders another one. Chunks in 1258 bins are kept in size order, with ties going to the 1259 approximately least recently used chunk. 1260 1261 The chunks in each bin are maintained in decreasing sorted order by 1262 size. This is irrelevant for the small bins, which all contain 1263 the same-sized chunks, but facilitates best-fit allocation for 1264 larger chunks. (These lists are just sequential. Keeping them in 1265 order almost never requires enough traversal to warrant using 1266 fancier ordered data structures.) Chunks of the same size are 1267 linked with the most recently freed at the front, and allocations 1268 are taken from the back. This results in LRU or FIFO allocation 1269 order, which tends to give each chunk an equal opportunity to be 1270 consolidated with adjacent freed chunks, resulting in larger free 1271 chunks and less fragmentation. 1272 1273 * `top': The top-most available chunk (i.e., the one bordering the 1274 end of available memory) is treated specially. It is never 1275 included in any bin, is used only if no other chunk is 1276 available, and is released back to the system if it is very 1277 large (see M_TRIM_THRESHOLD). 1278 1279 * `last_remainder': A bin holding only the remainder of the 1280 most recently split (non-top) chunk. This bin is checked 1281 before other non-fitting chunks, so as to provide better 1282 locality for runs of sequentially allocated chunks. 1283 1284 * Implicitly, through the host system's memory mapping tables. 1285 If supported, requests greater than a threshold are usually 1286 serviced via calls to mmap, and then later released via munmap. 1287 1288 */ 1289 1290 1291 1292 1293 1294 1295 /* sizes, alignments */ 1296 1297 #define SIZE_SZ (sizeof(INTERNAL_SIZE_T)) 1298 #define MALLOC_ALIGNMENT (SIZE_SZ + SIZE_SZ) 1299 #define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1) 1300 #define MINSIZE (sizeof(struct malloc_chunk)) 1301 1302 /* conversion from malloc headers to user pointers, and back */ 1303 1304 #define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ)) 1305 #define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ)) 1306 1307 /* pad request bytes into a usable size */ 1308 1309 #define request2size(req) \ 1310 (((long)((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \ 1311 (long)(MINSIZE + MALLOC_ALIGN_MASK)) ? MINSIZE : \ 1312 (((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) & ~(MALLOC_ALIGN_MASK))) 1313 1314 /* Check if m has acceptable alignment */ 1315 1316 #define aligned_OK(m) (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0) 1317 1318 1319 1320 1321 /* 1322 Physical chunk operations 1323 */ 1324 1325 1326 /* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */ 1327 1328 #define PREV_INUSE 0x1 1329 1330 /* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */ 1331 1332 #define IS_MMAPPED 0x2 1333 1334 /* Bits to mask off when extracting size */ 1335 1336 #define SIZE_BITS (PREV_INUSE|IS_MMAPPED) 1337 1338 1339 /* Ptr to next physical malloc_chunk. */ 1340 1341 #define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) )) 1342 1343 /* Ptr to previous physical malloc_chunk */ 1344 1345 #define prev_chunk(p)\ 1346 ((mchunkptr)( ((char*)(p)) - ((p)->prev_size) )) 1347 1348 1349 /* Treat space at ptr + offset as a chunk */ 1350 1351 #define chunk_at_offset(p, s) ((mchunkptr)(((char*)(p)) + (s))) 1352 1353 1354 1355 1356 /* 1357 Dealing with use bits 1358 */ 1359 1360 /* extract p's inuse bit */ 1361 1362 #define inuse(p)\ 1363 ((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE) 1364 1365 /* extract inuse bit of previous chunk */ 1366 1367 #define prev_inuse(p) ((p)->size & PREV_INUSE) 1368 1369 /* check for mmap()'ed chunk */ 1370 1371 #define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED) 1372 1373 /* set/clear chunk as in use without otherwise disturbing */ 1374 1375 #define set_inuse(p)\ 1376 ((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE 1377 1378 #define clear_inuse(p)\ 1379 ((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE) 1380 1381 /* check/set/clear inuse bits in known places */ 1382 1383 #define inuse_bit_at_offset(p, s)\ 1384 (((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE) 1385 1386 #define set_inuse_bit_at_offset(p, s)\ 1387 (((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE) 1388 1389 #define clear_inuse_bit_at_offset(p, s)\ 1390 (((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE)) 1391 1392 1393 1394 1395 /* 1396 Dealing with size fields 1397 */ 1398 1399 /* Get size, ignoring use bits */ 1400 1401 #define chunksize(p) ((p)->size & ~(SIZE_BITS)) 1402 1403 /* Set size at head, without disturbing its use bit */ 1404 1405 #define set_head_size(p, s) ((p)->size = (((p)->size & PREV_INUSE) | (s))) 1406 1407 /* Set size/use ignoring previous bits in header */ 1408 1409 #define set_head(p, s) ((p)->size = (s)) 1410 1411 /* Set size at footer (only when chunk is not in use) */ 1412 1413 #define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_size = (s)) 1414 1415 1416 1417 1418 1419 /* 1420 Bins 1421 1422 The bins, `av_' are an array of pairs of pointers serving as the 1423 heads of (initially empty) doubly-linked lists of chunks, laid out 1424 in a way so that each pair can be treated as if it were in a 1425 malloc_chunk. (This way, the fd/bk offsets for linking bin heads 1426 and chunks are the same). 1427 1428 Bins for sizes < 512 bytes contain chunks of all the same size, spaced 1429 8 bytes apart. Larger bins are approximately logarithmically 1430 spaced. (See the table below.) The `av_' array is never mentioned 1431 directly in the code, but instead via bin access macros. 1432 1433 Bin layout: 1434 1435 64 bins of size 8 1436 32 bins of size 64 1437 16 bins of size 512 1438 8 bins of size 4096 1439 4 bins of size 32768 1440 2 bins of size 262144 1441 1 bin of size what's left 1442 1443 There is actually a little bit of slop in the numbers in bin_index 1444 for the sake of speed. This makes no difference elsewhere. 1445 1446 The special chunks `top' and `last_remainder' get their own bins, 1447 (this is implemented via yet more trickery with the av_ array), 1448 although `top' is never properly linked to its bin since it is 1449 always handled specially. 1450 1451 */ 1452 1453 #define NAV 128 /* number of bins */ 1454 1455 typedef struct malloc_chunk* mbinptr; 1456 1457 /* access macros */ 1458 1459 #define bin_at(i) ((mbinptr)((char*)&(av_[2*(i) + 2]) - 2*SIZE_SZ)) 1460 #define next_bin(b) ((mbinptr)((char*)(b) + 2 * sizeof(mbinptr))) 1461 #define prev_bin(b) ((mbinptr)((char*)(b) - 2 * sizeof(mbinptr))) 1462 1463 /* 1464 The first 2 bins are never indexed. The corresponding av_ cells are instead 1465 used for bookkeeping. This is not to save space, but to simplify 1466 indexing, maintain locality, and avoid some initialization tests. 1467 */ 1468 1469 #define top (bin_at(0)->fd) /* The topmost chunk */ 1470 #define last_remainder (bin_at(1)) /* remainder from last split */ 1471 1472 1473 /* 1474 Because top initially points to its own bin with initial 1475 zero size, thus forcing extension on the first malloc request, 1476 we avoid having any special code in malloc to check whether 1477 it even exists yet. But we still need to in malloc_extend_top. 1478 */ 1479 1480 #define initial_top ((mchunkptr)(bin_at(0))) 1481 1482 /* Helper macro to initialize bins */ 1483 1484 #define IAV(i) bin_at(i), bin_at(i) 1485 1486 static mbinptr av_[NAV * 2 + 2] = { 1487 0, 0, 1488 IAV(0), IAV(1), IAV(2), IAV(3), IAV(4), IAV(5), IAV(6), IAV(7), 1489 IAV(8), IAV(9), IAV(10), IAV(11), IAV(12), IAV(13), IAV(14), IAV(15), 1490 IAV(16), IAV(17), IAV(18), IAV(19), IAV(20), IAV(21), IAV(22), IAV(23), 1491 IAV(24), IAV(25), IAV(26), IAV(27), IAV(28), IAV(29), IAV(30), IAV(31), 1492 IAV(32), IAV(33), IAV(34), IAV(35), IAV(36), IAV(37), IAV(38), IAV(39), 1493 IAV(40), IAV(41), IAV(42), IAV(43), IAV(44), IAV(45), IAV(46), IAV(47), 1494 IAV(48), IAV(49), IAV(50), IAV(51), IAV(52), IAV(53), IAV(54), IAV(55), 1495 IAV(56), IAV(57), IAV(58), IAV(59), IAV(60), IAV(61), IAV(62), IAV(63), 1496 IAV(64), IAV(65), IAV(66), IAV(67), IAV(68), IAV(69), IAV(70), IAV(71), 1497 IAV(72), IAV(73), IAV(74), IAV(75), IAV(76), IAV(77), IAV(78), IAV(79), 1498 IAV(80), IAV(81), IAV(82), IAV(83), IAV(84), IAV(85), IAV(86), IAV(87), 1499 IAV(88), IAV(89), IAV(90), IAV(91), IAV(92), IAV(93), IAV(94), IAV(95), 1500 IAV(96), IAV(97), IAV(98), IAV(99), IAV(100), IAV(101), IAV(102), IAV(103), 1501 IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111), 1502 IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119), 1503 IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127) 1504 }; 1505 1506 void malloc_bin_reloc (void) 1507 { 1508 DECLARE_GLOBAL_DATA_PTR; 1509 1510 unsigned long *p = (unsigned long *)(&av_[2]); 1511 int i; 1512 for (i=2; i<(sizeof(av_)/sizeof(mbinptr)); ++i) { 1513 *p++ += gd->reloc_off; 1514 } 1515 } 1516 1517 1518 /* field-extraction macros */ 1519 1520 #define first(b) ((b)->fd) 1521 #define last(b) ((b)->bk) 1522 1523 /* 1524 Indexing into bins 1525 */ 1526 1527 #define bin_index(sz) \ 1528 (((((unsigned long)(sz)) >> 9) == 0) ? (((unsigned long)(sz)) >> 3): \ 1529 ((((unsigned long)(sz)) >> 9) <= 4) ? 56 + (((unsigned long)(sz)) >> 6): \ 1530 ((((unsigned long)(sz)) >> 9) <= 20) ? 91 + (((unsigned long)(sz)) >> 9): \ 1531 ((((unsigned long)(sz)) >> 9) <= 84) ? 110 + (((unsigned long)(sz)) >> 12): \ 1532 ((((unsigned long)(sz)) >> 9) <= 340) ? 119 + (((unsigned long)(sz)) >> 15): \ 1533 ((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18): \ 1534 126) 1535 /* 1536 bins for chunks < 512 are all spaced 8 bytes apart, and hold 1537 identically sized chunks. This is exploited in malloc. 1538 */ 1539 1540 #define MAX_SMALLBIN 63 1541 #define MAX_SMALLBIN_SIZE 512 1542 #define SMALLBIN_WIDTH 8 1543 1544 #define smallbin_index(sz) (((unsigned long)(sz)) >> 3) 1545 1546 /* 1547 Requests are `small' if both the corresponding and the next bin are small 1548 */ 1549 1550 #define is_small_request(nb) (nb < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH) 1551 1552 1553 1554 /* 1555 To help compensate for the large number of bins, a one-level index 1556 structure is used for bin-by-bin searching. `binblocks' is a 1557 one-word bitvector recording whether groups of BINBLOCKWIDTH bins 1558 have any (possibly) non-empty bins, so they can be skipped over 1559 all at once during during traversals. The bits are NOT always 1560 cleared as soon as all bins in a block are empty, but instead only 1561 when all are noticed to be empty during traversal in malloc. 1562 */ 1563 1564 #define BINBLOCKWIDTH 4 /* bins per block */ 1565 1566 #define binblocks (bin_at(0)->size) /* bitvector of nonempty blocks */ 1567 1568 /* bin<->block macros */ 1569 1570 #define idx2binblock(ix) ((unsigned)1 << (ix / BINBLOCKWIDTH)) 1571 #define mark_binblock(ii) (binblocks |= idx2binblock(ii)) 1572 #define clear_binblock(ii) (binblocks &= ~(idx2binblock(ii))) 1573 1574 1575 1576 1577 1578 /* Other static bookkeeping data */ 1579 1580 /* variables holding tunable values */ 1581 1582 static unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD; 1583 static unsigned long top_pad = DEFAULT_TOP_PAD; 1584 static unsigned int n_mmaps_max = DEFAULT_MMAP_MAX; 1585 static unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD; 1586 1587 /* The first value returned from sbrk */ 1588 static char* sbrk_base = (char*)(-1); 1589 1590 /* The maximum memory obtained from system via sbrk */ 1591 static unsigned long max_sbrked_mem = 0; 1592 1593 /* The maximum via either sbrk or mmap */ 1594 static unsigned long max_total_mem = 0; 1595 1596 /* internal working copy of mallinfo */ 1597 static struct mallinfo current_mallinfo = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; 1598 1599 /* The total memory obtained from system via sbrk */ 1600 #define sbrked_mem (current_mallinfo.arena) 1601 1602 /* Tracking mmaps */ 1603 1604 #if 0 1605 static unsigned int n_mmaps = 0; 1606 #endif /* 0 */ 1607 static unsigned long mmapped_mem = 0; 1608 #if HAVE_MMAP 1609 static unsigned int max_n_mmaps = 0; 1610 static unsigned long max_mmapped_mem = 0; 1611 #endif 1612 1613 1614 1615 /* 1616 Debugging support 1617 */ 1618 1619 #ifdef DEBUG 1620 1621 1622 /* 1623 These routines make a number of assertions about the states 1624 of data structures that should be true at all times. If any 1625 are not true, it's very likely that a user program has somehow 1626 trashed memory. (It's also possible that there is a coding error 1627 in malloc. In which case, please report it!) 1628 */ 1629 1630 #if __STD_C 1631 static void do_check_chunk(mchunkptr p) 1632 #else 1633 static void do_check_chunk(p) mchunkptr p; 1634 #endif 1635 { 1636 #if 0 /* causes warnings because assert() is off */ 1637 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE; 1638 #endif /* 0 */ 1639 1640 /* No checkable chunk is mmapped */ 1641 assert(!chunk_is_mmapped(p)); 1642 1643 /* Check for legal address ... */ 1644 assert((char*)p >= sbrk_base); 1645 if (p != top) 1646 assert((char*)p + sz <= (char*)top); 1647 else 1648 assert((char*)p + sz <= sbrk_base + sbrked_mem); 1649 1650 } 1651 1652 1653 #if __STD_C 1654 static void do_check_free_chunk(mchunkptr p) 1655 #else 1656 static void do_check_free_chunk(p) mchunkptr p; 1657 #endif 1658 { 1659 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE; 1660 #if 0 /* causes warnings because assert() is off */ 1661 mchunkptr next = chunk_at_offset(p, sz); 1662 #endif /* 0 */ 1663 1664 do_check_chunk(p); 1665 1666 /* Check whether it claims to be free ... */ 1667 assert(!inuse(p)); 1668 1669 /* Unless a special marker, must have OK fields */ 1670 if ((long)sz >= (long)MINSIZE) 1671 { 1672 assert((sz & MALLOC_ALIGN_MASK) == 0); 1673 assert(aligned_OK(chunk2mem(p))); 1674 /* ... matching footer field */ 1675 assert(next->prev_size == sz); 1676 /* ... and is fully consolidated */ 1677 assert(prev_inuse(p)); 1678 assert (next == top || inuse(next)); 1679 1680 /* ... and has minimally sane links */ 1681 assert(p->fd->bk == p); 1682 assert(p->bk->fd == p); 1683 } 1684 else /* markers are always of size SIZE_SZ */ 1685 assert(sz == SIZE_SZ); 1686 } 1687 1688 #if __STD_C 1689 static void do_check_inuse_chunk(mchunkptr p) 1690 #else 1691 static void do_check_inuse_chunk(p) mchunkptr p; 1692 #endif 1693 { 1694 mchunkptr next = next_chunk(p); 1695 do_check_chunk(p); 1696 1697 /* Check whether it claims to be in use ... */ 1698 assert(inuse(p)); 1699 1700 /* ... and is surrounded by OK chunks. 1701 Since more things can be checked with free chunks than inuse ones, 1702 if an inuse chunk borders them and debug is on, it's worth doing them. 1703 */ 1704 if (!prev_inuse(p)) 1705 { 1706 mchunkptr prv = prev_chunk(p); 1707 assert(next_chunk(prv) == p); 1708 do_check_free_chunk(prv); 1709 } 1710 if (next == top) 1711 { 1712 assert(prev_inuse(next)); 1713 assert(chunksize(next) >= MINSIZE); 1714 } 1715 else if (!inuse(next)) 1716 do_check_free_chunk(next); 1717 1718 } 1719 1720 #if __STD_C 1721 static void do_check_malloced_chunk(mchunkptr p, INTERNAL_SIZE_T s) 1722 #else 1723 static void do_check_malloced_chunk(p, s) mchunkptr p; INTERNAL_SIZE_T s; 1724 #endif 1725 { 1726 #if 0 /* causes warnings because assert() is off */ 1727 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE; 1728 long room = sz - s; 1729 #endif /* 0 */ 1730 1731 do_check_inuse_chunk(p); 1732 1733 /* Legal size ... */ 1734 assert((long)sz >= (long)MINSIZE); 1735 assert((sz & MALLOC_ALIGN_MASK) == 0); 1736 assert(room >= 0); 1737 assert(room < (long)MINSIZE); 1738 1739 /* ... and alignment */ 1740 assert(aligned_OK(chunk2mem(p))); 1741 1742 1743 /* ... and was allocated at front of an available chunk */ 1744 assert(prev_inuse(p)); 1745 1746 } 1747 1748 1749 #define check_free_chunk(P) do_check_free_chunk(P) 1750 #define check_inuse_chunk(P) do_check_inuse_chunk(P) 1751 #define check_chunk(P) do_check_chunk(P) 1752 #define check_malloced_chunk(P,N) do_check_malloced_chunk(P,N) 1753 #else 1754 #define check_free_chunk(P) 1755 #define check_inuse_chunk(P) 1756 #define check_chunk(P) 1757 #define check_malloced_chunk(P,N) 1758 #endif 1759 1760 1761 1762 /* 1763 Macro-based internal utilities 1764 */ 1765 1766 1767 /* 1768 Linking chunks in bin lists. 1769 Call these only with variables, not arbitrary expressions, as arguments. 1770 */ 1771 1772 /* 1773 Place chunk p of size s in its bin, in size order, 1774 putting it ahead of others of same size. 1775 */ 1776 1777 1778 #define frontlink(P, S, IDX, BK, FD) \ 1779 { \ 1780 if (S < MAX_SMALLBIN_SIZE) \ 1781 { \ 1782 IDX = smallbin_index(S); \ 1783 mark_binblock(IDX); \ 1784 BK = bin_at(IDX); \ 1785 FD = BK->fd; \ 1786 P->bk = BK; \ 1787 P->fd = FD; \ 1788 FD->bk = BK->fd = P; \ 1789 } \ 1790 else \ 1791 { \ 1792 IDX = bin_index(S); \ 1793 BK = bin_at(IDX); \ 1794 FD = BK->fd; \ 1795 if (FD == BK) mark_binblock(IDX); \ 1796 else \ 1797 { \ 1798 while (FD != BK && S < chunksize(FD)) FD = FD->fd; \ 1799 BK = FD->bk; \ 1800 } \ 1801 P->bk = BK; \ 1802 P->fd = FD; \ 1803 FD->bk = BK->fd = P; \ 1804 } \ 1805 } 1806 1807 1808 /* take a chunk off a list */ 1809 1810 #define unlink(P, BK, FD) \ 1811 { \ 1812 BK = P->bk; \ 1813 FD = P->fd; \ 1814 FD->bk = BK; \ 1815 BK->fd = FD; \ 1816 } \ 1817 1818 /* Place p as the last remainder */ 1819 1820 #define link_last_remainder(P) \ 1821 { \ 1822 last_remainder->fd = last_remainder->bk = P; \ 1823 P->fd = P->bk = last_remainder; \ 1824 } 1825 1826 /* Clear the last_remainder bin */ 1827 1828 #define clear_last_remainder \ 1829 (last_remainder->fd = last_remainder->bk = last_remainder) 1830 1831 1832 1833 1834 1835 1836 /* Routines dealing with mmap(). */ 1837 1838 #if HAVE_MMAP 1839 1840 #if __STD_C 1841 static mchunkptr mmap_chunk(size_t size) 1842 #else 1843 static mchunkptr mmap_chunk(size) size_t size; 1844 #endif 1845 { 1846 size_t page_mask = malloc_getpagesize - 1; 1847 mchunkptr p; 1848 1849 #ifndef MAP_ANONYMOUS 1850 static int fd = -1; 1851 #endif 1852 1853 if(n_mmaps >= n_mmaps_max) return 0; /* too many regions */ 1854 1855 /* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because 1856 * there is no following chunk whose prev_size field could be used. 1857 */ 1858 size = (size + SIZE_SZ + page_mask) & ~page_mask; 1859 1860 #ifdef MAP_ANONYMOUS 1861 p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, 1862 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 1863 #else /* !MAP_ANONYMOUS */ 1864 if (fd < 0) 1865 { 1866 fd = open("/dev/zero", O_RDWR); 1867 if(fd < 0) return 0; 1868 } 1869 p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); 1870 #endif 1871 1872 if(p == (mchunkptr)-1) return 0; 1873 1874 n_mmaps++; 1875 if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps; 1876 1877 /* We demand that eight bytes into a page must be 8-byte aligned. */ 1878 assert(aligned_OK(chunk2mem(p))); 1879 1880 /* The offset to the start of the mmapped region is stored 1881 * in the prev_size field of the chunk; normally it is zero, 1882 * but that can be changed in memalign(). 1883 */ 1884 p->prev_size = 0; 1885 set_head(p, size|IS_MMAPPED); 1886 1887 mmapped_mem += size; 1888 if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem) 1889 max_mmapped_mem = mmapped_mem; 1890 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) 1891 max_total_mem = mmapped_mem + sbrked_mem; 1892 return p; 1893 } 1894 1895 #if __STD_C 1896 static void munmap_chunk(mchunkptr p) 1897 #else 1898 static void munmap_chunk(p) mchunkptr p; 1899 #endif 1900 { 1901 INTERNAL_SIZE_T size = chunksize(p); 1902 int ret; 1903 1904 assert (chunk_is_mmapped(p)); 1905 assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem)); 1906 assert((n_mmaps > 0)); 1907 assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0); 1908 1909 n_mmaps--; 1910 mmapped_mem -= (size + p->prev_size); 1911 1912 ret = munmap((char *)p - p->prev_size, size + p->prev_size); 1913 1914 /* munmap returns non-zero on failure */ 1915 assert(ret == 0); 1916 } 1917 1918 #if HAVE_MREMAP 1919 1920 #if __STD_C 1921 static mchunkptr mremap_chunk(mchunkptr p, size_t new_size) 1922 #else 1923 static mchunkptr mremap_chunk(p, new_size) mchunkptr p; size_t new_size; 1924 #endif 1925 { 1926 size_t page_mask = malloc_getpagesize - 1; 1927 INTERNAL_SIZE_T offset = p->prev_size; 1928 INTERNAL_SIZE_T size = chunksize(p); 1929 char *cp; 1930 1931 assert (chunk_is_mmapped(p)); 1932 assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem)); 1933 assert((n_mmaps > 0)); 1934 assert(((size + offset) & (malloc_getpagesize-1)) == 0); 1935 1936 /* Note the extra SIZE_SZ overhead as in mmap_chunk(). */ 1937 new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask; 1938 1939 cp = (char *)mremap((char *)p - offset, size + offset, new_size, 1); 1940 1941 if (cp == (char *)-1) return 0; 1942 1943 p = (mchunkptr)(cp + offset); 1944 1945 assert(aligned_OK(chunk2mem(p))); 1946 1947 assert((p->prev_size == offset)); 1948 set_head(p, (new_size - offset)|IS_MMAPPED); 1949 1950 mmapped_mem -= size + offset; 1951 mmapped_mem += new_size; 1952 if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem) 1953 max_mmapped_mem = mmapped_mem; 1954 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) 1955 max_total_mem = mmapped_mem + sbrked_mem; 1956 return p; 1957 } 1958 1959 #endif /* HAVE_MREMAP */ 1960 1961 #endif /* HAVE_MMAP */ 1962 1963 1964 1965 1966 /* 1967 Extend the top-most chunk by obtaining memory from system. 1968 Main interface to sbrk (but see also malloc_trim). 1969 */ 1970 1971 #if __STD_C 1972 static void malloc_extend_top(INTERNAL_SIZE_T nb) 1973 #else 1974 static void malloc_extend_top(nb) INTERNAL_SIZE_T nb; 1975 #endif 1976 { 1977 char* brk; /* return value from sbrk */ 1978 INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */ 1979 INTERNAL_SIZE_T correction; /* bytes for 2nd sbrk call */ 1980 char* new_brk; /* return of 2nd sbrk call */ 1981 INTERNAL_SIZE_T top_size; /* new size of top chunk */ 1982 1983 mchunkptr old_top = top; /* Record state of old top */ 1984 INTERNAL_SIZE_T old_top_size = chunksize(old_top); 1985 char* old_end = (char*)(chunk_at_offset(old_top, old_top_size)); 1986 1987 /* Pad request with top_pad plus minimal overhead */ 1988 1989 INTERNAL_SIZE_T sbrk_size = nb + top_pad + MINSIZE; 1990 unsigned long pagesz = malloc_getpagesize; 1991 1992 /* If not the first time through, round to preserve page boundary */ 1993 /* Otherwise, we need to correct to a page size below anyway. */ 1994 /* (We also correct below if an intervening foreign sbrk call.) */ 1995 1996 if (sbrk_base != (char*)(-1)) 1997 sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1); 1998 1999 brk = (char*)(MORECORE (sbrk_size)); 2000 2001 /* Fail if sbrk failed or if a foreign sbrk call killed our space */ 2002 if (brk == (char*)(MORECORE_FAILURE) || 2003 (brk < old_end && old_top != initial_top)) 2004 return; 2005 2006 sbrked_mem += sbrk_size; 2007 2008 if (brk == old_end) /* can just add bytes to current top */ 2009 { 2010 top_size = sbrk_size + old_top_size; 2011 set_head(top, top_size | PREV_INUSE); 2012 } 2013 else 2014 { 2015 if (sbrk_base == (char*)(-1)) /* First time through. Record base */ 2016 sbrk_base = brk; 2017 else /* Someone else called sbrk(). Count those bytes as sbrked_mem. */ 2018 sbrked_mem += brk - (char*)old_end; 2019 2020 /* Guarantee alignment of first new chunk made from this space */ 2021 front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK; 2022 if (front_misalign > 0) 2023 { 2024 correction = (MALLOC_ALIGNMENT) - front_misalign; 2025 brk += correction; 2026 } 2027 else 2028 correction = 0; 2029 2030 /* Guarantee the next brk will be at a page boundary */ 2031 2032 correction += ((((unsigned long)(brk + sbrk_size))+(pagesz-1)) & 2033 ~(pagesz - 1)) - ((unsigned long)(brk + sbrk_size)); 2034 2035 /* Allocate correction */ 2036 new_brk = (char*)(MORECORE (correction)); 2037 if (new_brk == (char*)(MORECORE_FAILURE)) return; 2038 2039 sbrked_mem += correction; 2040 2041 top = (mchunkptr)brk; 2042 top_size = new_brk - brk + correction; 2043 set_head(top, top_size | PREV_INUSE); 2044 2045 if (old_top != initial_top) 2046 { 2047 2048 /* There must have been an intervening foreign sbrk call. */ 2049 /* A double fencepost is necessary to prevent consolidation */ 2050 2051 /* If not enough space to do this, then user did something very wrong */ 2052 if (old_top_size < MINSIZE) 2053 { 2054 set_head(top, PREV_INUSE); /* will force null return from malloc */ 2055 return; 2056 } 2057 2058 /* Also keep size a multiple of MALLOC_ALIGNMENT */ 2059 old_top_size = (old_top_size - 3*SIZE_SZ) & ~MALLOC_ALIGN_MASK; 2060 set_head_size(old_top, old_top_size); 2061 chunk_at_offset(old_top, old_top_size )->size = 2062 SIZE_SZ|PREV_INUSE; 2063 chunk_at_offset(old_top, old_top_size + SIZE_SZ)->size = 2064 SIZE_SZ|PREV_INUSE; 2065 /* If possible, release the rest. */ 2066 if (old_top_size >= MINSIZE) 2067 fREe(chunk2mem(old_top)); 2068 } 2069 } 2070 2071 if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem) 2072 max_sbrked_mem = sbrked_mem; 2073 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) 2074 max_total_mem = mmapped_mem + sbrked_mem; 2075 2076 /* We always land on a page boundary */ 2077 assert(((unsigned long)((char*)top + top_size) & (pagesz - 1)) == 0); 2078 } 2079 2080 2081 2082 2083 /* Main public routines */ 2084 2085 2086 /* 2087 Malloc Algorthim: 2088 2089 The requested size is first converted into a usable form, `nb'. 2090 This currently means to add 4 bytes overhead plus possibly more to 2091 obtain 8-byte alignment and/or to obtain a size of at least 2092 MINSIZE (currently 16 bytes), the smallest allocatable size. 2093 (All fits are considered `exact' if they are within MINSIZE bytes.) 2094 2095 From there, the first successful of the following steps is taken: 2096 2097 1. The bin corresponding to the request size is scanned, and if 2098 a chunk of exactly the right size is found, it is taken. 2099 2100 2. The most recently remaindered chunk is used if it is big 2101 enough. This is a form of (roving) first fit, used only in 2102 the absence of exact fits. Runs of consecutive requests use 2103 the remainder of the chunk used for the previous such request 2104 whenever possible. This limited use of a first-fit style 2105 allocation strategy tends to give contiguous chunks 2106 coextensive lifetimes, which improves locality and can reduce 2107 fragmentation in the long run. 2108 2109 3. Other bins are scanned in increasing size order, using a 2110 chunk big enough to fulfill the request, and splitting off 2111 any remainder. This search is strictly by best-fit; i.e., 2112 the smallest (with ties going to approximately the least 2113 recently used) chunk that fits is selected. 2114 2115 4. If large enough, the chunk bordering the end of memory 2116 (`top') is split off. (This use of `top' is in accord with 2117 the best-fit search rule. In effect, `top' is treated as 2118 larger (and thus less well fitting) than any other available 2119 chunk since it can be extended to be as large as necessary 2120 (up to system limitations). 2121 2122 5. If the request size meets the mmap threshold and the 2123 system supports mmap, and there are few enough currently 2124 allocated mmapped regions, and a call to mmap succeeds, 2125 the request is allocated via direct memory mapping. 2126 2127 6. Otherwise, the top of memory is extended by 2128 obtaining more space from the system (normally using sbrk, 2129 but definable to anything else via the MORECORE macro). 2130 Memory is gathered from the system (in system page-sized 2131 units) in a way that allows chunks obtained across different 2132 sbrk calls to be consolidated, but does not require 2133 contiguous memory. Thus, it should be safe to intersperse 2134 mallocs with other sbrk calls. 2135 2136 2137 All allocations are made from the the `lowest' part of any found 2138 chunk. (The implementation invariant is that prev_inuse is 2139 always true of any allocated chunk; i.e., that each allocated 2140 chunk borders either a previously allocated and still in-use chunk, 2141 or the base of its memory arena.) 2142 2143 */ 2144 2145 #if __STD_C 2146 Void_t* mALLOc(size_t bytes) 2147 #else 2148 Void_t* mALLOc(bytes) size_t bytes; 2149 #endif 2150 { 2151 mchunkptr victim; /* inspected/selected chunk */ 2152 INTERNAL_SIZE_T victim_size; /* its size */ 2153 int idx; /* index for bin traversal */ 2154 mbinptr bin; /* associated bin */ 2155 mchunkptr remainder; /* remainder from a split */ 2156 long remainder_size; /* its size */ 2157 int remainder_index; /* its bin index */ 2158 unsigned long block; /* block traverser bit */ 2159 int startidx; /* first bin of a traversed block */ 2160 mchunkptr fwd; /* misc temp for linking */ 2161 mchunkptr bck; /* misc temp for linking */ 2162 mbinptr q; /* misc temp */ 2163 2164 INTERNAL_SIZE_T nb; 2165 2166 if ((long)bytes < 0) return 0; 2167 2168 nb = request2size(bytes); /* padded request size; */ 2169 2170 /* Check for exact match in a bin */ 2171 2172 if (is_small_request(nb)) /* Faster version for small requests */ 2173 { 2174 idx = smallbin_index(nb); 2175 2176 /* No traversal or size check necessary for small bins. */ 2177 2178 q = bin_at(idx); 2179 victim = last(q); 2180 2181 /* Also scan the next one, since it would have a remainder < MINSIZE */ 2182 if (victim == q) 2183 { 2184 q = next_bin(q); 2185 victim = last(q); 2186 } 2187 if (victim != q) 2188 { 2189 victim_size = chunksize(victim); 2190 unlink(victim, bck, fwd); 2191 set_inuse_bit_at_offset(victim, victim_size); 2192 check_malloced_chunk(victim, nb); 2193 return chunk2mem(victim); 2194 } 2195 2196 idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */ 2197 2198 } 2199 else 2200 { 2201 idx = bin_index(nb); 2202 bin = bin_at(idx); 2203 2204 for (victim = last(bin); victim != bin; victim = victim->bk) 2205 { 2206 victim_size = chunksize(victim); 2207 remainder_size = victim_size - nb; 2208 2209 if (remainder_size >= (long)MINSIZE) /* too big */ 2210 { 2211 --idx; /* adjust to rescan below after checking last remainder */ 2212 break; 2213 } 2214 2215 else if (remainder_size >= 0) /* exact fit */ 2216 { 2217 unlink(victim, bck, fwd); 2218 set_inuse_bit_at_offset(victim, victim_size); 2219 check_malloced_chunk(victim, nb); 2220 return chunk2mem(victim); 2221 } 2222 } 2223 2224 ++idx; 2225 2226 } 2227 2228 /* Try to use the last split-off remainder */ 2229 2230 if ( (victim = last_remainder->fd) != last_remainder) 2231 { 2232 victim_size = chunksize(victim); 2233 remainder_size = victim_size - nb; 2234 2235 if (remainder_size >= (long)MINSIZE) /* re-split */ 2236 { 2237 remainder = chunk_at_offset(victim, nb); 2238 set_head(victim, nb | PREV_INUSE); 2239 link_last_remainder(remainder); 2240 set_head(remainder, remainder_size | PREV_INUSE); 2241 set_foot(remainder, remainder_size); 2242 check_malloced_chunk(victim, nb); 2243 return chunk2mem(victim); 2244 } 2245 2246 clear_last_remainder; 2247 2248 if (remainder_size >= 0) /* exhaust */ 2249 { 2250 set_inuse_bit_at_offset(victim, victim_size); 2251 check_malloced_chunk(victim, nb); 2252 return chunk2mem(victim); 2253 } 2254 2255 /* Else place in bin */ 2256 2257 frontlink(victim, victim_size, remainder_index, bck, fwd); 2258 } 2259 2260 /* 2261 If there are any possibly nonempty big-enough blocks, 2262 search for best fitting chunk by scanning bins in blockwidth units. 2263 */ 2264 2265 if ( (block = idx2binblock(idx)) <= binblocks) 2266 { 2267 2268 /* Get to the first marked block */ 2269 2270 if ( (block & binblocks) == 0) 2271 { 2272 /* force to an even block boundary */ 2273 idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH; 2274 block <<= 1; 2275 while ((block & binblocks) == 0) 2276 { 2277 idx += BINBLOCKWIDTH; 2278 block <<= 1; 2279 } 2280 } 2281 2282 /* For each possibly nonempty block ... */ 2283 for (;;) 2284 { 2285 startidx = idx; /* (track incomplete blocks) */ 2286 q = bin = bin_at(idx); 2287 2288 /* For each bin in this block ... */ 2289 do 2290 { 2291 /* Find and use first big enough chunk ... */ 2292 2293 for (victim = last(bin); victim != bin; victim = victim->bk) 2294 { 2295 victim_size = chunksize(victim); 2296 remainder_size = victim_size - nb; 2297 2298 if (remainder_size >= (long)MINSIZE) /* split */ 2299 { 2300 remainder = chunk_at_offset(victim, nb); 2301 set_head(victim, nb | PREV_INUSE); 2302 unlink(victim, bck, fwd); 2303 link_last_remainder(remainder); 2304 set_head(remainder, remainder_size | PREV_INUSE); 2305 set_foot(remainder, remainder_size); 2306 check_malloced_chunk(victim, nb); 2307 return chunk2mem(victim); 2308 } 2309 2310 else if (remainder_size >= 0) /* take */ 2311 { 2312 set_inuse_bit_at_offset(victim, victim_size); 2313 unlink(victim, bck, fwd); 2314 check_malloced_chunk(victim, nb); 2315 return chunk2mem(victim); 2316 } 2317 2318 } 2319 2320 bin = next_bin(bin); 2321 2322 } while ((++idx & (BINBLOCKWIDTH - 1)) != 0); 2323 2324 /* Clear out the block bit. */ 2325 2326 do /* Possibly backtrack to try to clear a partial block */ 2327 { 2328 if ((startidx & (BINBLOCKWIDTH - 1)) == 0) 2329 { 2330 binblocks &= ~block; 2331 break; 2332 } 2333 --startidx; 2334 q = prev_bin(q); 2335 } while (first(q) == q); 2336 2337 /* Get to the next possibly nonempty block */ 2338 2339 if ( (block <<= 1) <= binblocks && (block != 0) ) 2340 { 2341 while ((block & binblocks) == 0) 2342 { 2343 idx += BINBLOCKWIDTH; 2344 block <<= 1; 2345 } 2346 } 2347 else 2348 break; 2349 } 2350 } 2351 2352 2353 /* Try to use top chunk */ 2354 2355 /* Require that there be a remainder, ensuring top always exists */ 2356 if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE) 2357 { 2358 2359 #if HAVE_MMAP 2360 /* If big and would otherwise need to extend, try to use mmap instead */ 2361 if ((unsigned long)nb >= (unsigned long)mmap_threshold && 2362 (victim = mmap_chunk(nb)) != 0) 2363 return chunk2mem(victim); 2364 #endif 2365 2366 /* Try to extend */ 2367 malloc_extend_top(nb); 2368 if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE) 2369 return 0; /* propagate failure */ 2370 } 2371 2372 victim = top; 2373 set_head(victim, nb | PREV_INUSE); 2374 top = chunk_at_offset(victim, nb); 2375 set_head(top, remainder_size | PREV_INUSE); 2376 check_malloced_chunk(victim, nb); 2377 return chunk2mem(victim); 2378 2379 } 2380 2381 2382 2383 2384 /* 2385 2386 free() algorithm : 2387 2388 cases: 2389 2390 1. free(0) has no effect. 2391 2392 2. If the chunk was allocated via mmap, it is release via munmap(). 2393 2394 3. If a returned chunk borders the current high end of memory, 2395 it is consolidated into the top, and if the total unused 2396 topmost memory exceeds the trim threshold, malloc_trim is 2397 called. 2398 2399 4. Other chunks are consolidated as they arrive, and 2400 placed in corresponding bins. (This includes the case of 2401 consolidating with the current `last_remainder'). 2402 2403 */ 2404 2405 2406 #if __STD_C 2407 void fREe(Void_t* mem) 2408 #else 2409 void fREe(mem) Void_t* mem; 2410 #endif 2411 { 2412 mchunkptr p; /* chunk corresponding to mem */ 2413 INTERNAL_SIZE_T hd; /* its head field */ 2414 INTERNAL_SIZE_T sz; /* its size */ 2415 int idx; /* its bin index */ 2416 mchunkptr next; /* next contiguous chunk */ 2417 INTERNAL_SIZE_T nextsz; /* its size */ 2418 INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */ 2419 mchunkptr bck; /* misc temp for linking */ 2420 mchunkptr fwd; /* misc temp for linking */ 2421 int islr; /* track whether merging with last_remainder */ 2422 2423 if (mem == 0) /* free(0) has no effect */ 2424 return; 2425 2426 p = mem2chunk(mem); 2427 hd = p->size; 2428 2429 #if HAVE_MMAP 2430 if (hd & IS_MMAPPED) /* release mmapped memory. */ 2431 { 2432 munmap_chunk(p); 2433 return; 2434 } 2435 #endif 2436 2437 check_inuse_chunk(p); 2438 2439 sz = hd & ~PREV_INUSE; 2440 next = chunk_at_offset(p, sz); 2441 nextsz = chunksize(next); 2442 2443 if (next == top) /* merge with top */ 2444 { 2445 sz += nextsz; 2446 2447 if (!(hd & PREV_INUSE)) /* consolidate backward */ 2448 { 2449 prevsz = p->prev_size; 2450 p = chunk_at_offset(p, -((long) prevsz)); 2451 sz += prevsz; 2452 unlink(p, bck, fwd); 2453 } 2454 2455 set_head(p, sz | PREV_INUSE); 2456 top = p; 2457 if ((unsigned long)(sz) >= (unsigned long)trim_threshold) 2458 malloc_trim(top_pad); 2459 return; 2460 } 2461 2462 set_head(next, nextsz); /* clear inuse bit */ 2463 2464 islr = 0; 2465 2466 if (!(hd & PREV_INUSE)) /* consolidate backward */ 2467 { 2468 prevsz = p->prev_size; 2469 p = chunk_at_offset(p, -((long) prevsz)); 2470 sz += prevsz; 2471 2472 if (p->fd == last_remainder) /* keep as last_remainder */ 2473 islr = 1; 2474 else 2475 unlink(p, bck, fwd); 2476 } 2477 2478 if (!(inuse_bit_at_offset(next, nextsz))) /* consolidate forward */ 2479 { 2480 sz += nextsz; 2481 2482 if (!islr && next->fd == last_remainder) /* re-insert last_remainder */ 2483 { 2484 islr = 1; 2485 link_last_remainder(p); 2486 } 2487 else 2488 unlink(next, bck, fwd); 2489 } 2490 2491 2492 set_head(p, sz | PREV_INUSE); 2493 set_foot(p, sz); 2494 if (!islr) 2495 frontlink(p, sz, idx, bck, fwd); 2496 } 2497 2498 2499 2500 2501 2502 /* 2503 2504 Realloc algorithm: 2505 2506 Chunks that were obtained via mmap cannot be extended or shrunk 2507 unless HAVE_MREMAP is defined, in which case mremap is used. 2508 Otherwise, if their reallocation is for additional space, they are 2509 copied. If for less, they are just left alone. 2510 2511 Otherwise, if the reallocation is for additional space, and the 2512 chunk can be extended, it is, else a malloc-copy-free sequence is 2513 taken. There are several different ways that a chunk could be 2514 extended. All are tried: 2515 2516 * Extending forward into following adjacent free chunk. 2517 * Shifting backwards, joining preceding adjacent space 2518 * Both shifting backwards and extending forward. 2519 * Extending into newly sbrked space 2520 2521 Unless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with a 2522 size argument of zero (re)allocates a minimum-sized chunk. 2523 2524 If the reallocation is for less space, and the new request is for 2525 a `small' (<512 bytes) size, then the newly unused space is lopped 2526 off and freed. 2527 2528 The old unix realloc convention of allowing the last-free'd chunk 2529 to be used as an argument to realloc is no longer supported. 2530 I don't know of any programs still relying on this feature, 2531 and allowing it would also allow too many other incorrect 2532 usages of realloc to be sensible. 2533 2534 2535 */ 2536 2537 2538 #if __STD_C 2539 Void_t* rEALLOc(Void_t* oldmem, size_t bytes) 2540 #else 2541 Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes; 2542 #endif 2543 { 2544 INTERNAL_SIZE_T nb; /* padded request size */ 2545 2546 mchunkptr oldp; /* chunk corresponding to oldmem */ 2547 INTERNAL_SIZE_T oldsize; /* its size */ 2548 2549 mchunkptr newp; /* chunk to return */ 2550 INTERNAL_SIZE_T newsize; /* its size */ 2551 Void_t* newmem; /* corresponding user mem */ 2552 2553 mchunkptr next; /* next contiguous chunk after oldp */ 2554 INTERNAL_SIZE_T nextsize; /* its size */ 2555 2556 mchunkptr prev; /* previous contiguous chunk before oldp */ 2557 INTERNAL_SIZE_T prevsize; /* its size */ 2558 2559 mchunkptr remainder; /* holds split off extra space from newp */ 2560 INTERNAL_SIZE_T remainder_size; /* its size */ 2561 2562 mchunkptr bck; /* misc temp for linking */ 2563 mchunkptr fwd; /* misc temp for linking */ 2564 2565 #ifdef REALLOC_ZERO_BYTES_FREES 2566 if (bytes == 0) { fREe(oldmem); return 0; } 2567 #endif 2568 2569 if ((long)bytes < 0) return 0; 2570 2571 /* realloc of null is supposed to be same as malloc */ 2572 if (oldmem == 0) return mALLOc(bytes); 2573 2574 newp = oldp = mem2chunk(oldmem); 2575 newsize = oldsize = chunksize(oldp); 2576 2577 2578 nb = request2size(bytes); 2579 2580 #if HAVE_MMAP 2581 if (chunk_is_mmapped(oldp)) 2582 { 2583 #if HAVE_MREMAP 2584 newp = mremap_chunk(oldp, nb); 2585 if(newp) return chunk2mem(newp); 2586 #endif 2587 /* Note the extra SIZE_SZ overhead. */ 2588 if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing */ 2589 /* Must alloc, copy, free. */ 2590 newmem = mALLOc(bytes); 2591 if (newmem == 0) return 0; /* propagate failure */ 2592 MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ); 2593 munmap_chunk(oldp); 2594 return newmem; 2595 } 2596 #endif 2597 2598 check_inuse_chunk(oldp); 2599 2600 if ((long)(oldsize) < (long)(nb)) 2601 { 2602 2603 /* Try expanding forward */ 2604 2605 next = chunk_at_offset(oldp, oldsize); 2606 if (next == top || !inuse(next)) 2607 { 2608 nextsize = chunksize(next); 2609 2610 /* Forward into top only if a remainder */ 2611 if (next == top) 2612 { 2613 if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE)) 2614 { 2615 newsize += nextsize; 2616 top = chunk_at_offset(oldp, nb); 2617 set_head(top, (newsize - nb) | PREV_INUSE); 2618 set_head_size(oldp, nb); 2619 return chunk2mem(oldp); 2620 } 2621 } 2622 2623 /* Forward into next chunk */ 2624 else if (((long)(nextsize + newsize) >= (long)(nb))) 2625 { 2626 unlink(next, bck, fwd); 2627 newsize += nextsize; 2628 goto split; 2629 } 2630 } 2631 else 2632 { 2633 next = 0; 2634 nextsize = 0; 2635 } 2636 2637 /* Try shifting backwards. */ 2638 2639 if (!prev_inuse(oldp)) 2640 { 2641 prev = prev_chunk(oldp); 2642 prevsize = chunksize(prev); 2643 2644 /* try forward + backward first to save a later consolidation */ 2645 2646 if (next != 0) 2647 { 2648 /* into top */ 2649 if (next == top) 2650 { 2651 if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE)) 2652 { 2653 unlink(prev, bck, fwd); 2654 newp = prev; 2655 newsize += prevsize + nextsize; 2656 newmem = chunk2mem(newp); 2657 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); 2658 top = chunk_at_offset(newp, nb); 2659 set_head(top, (newsize - nb) | PREV_INUSE); 2660 set_head_size(newp, nb); 2661 return newmem; 2662 } 2663 } 2664 2665 /* into next chunk */ 2666 else if (((long)(nextsize + prevsize + newsize) >= (long)(nb))) 2667 { 2668 unlink(next, bck, fwd); 2669 unlink(prev, bck, fwd); 2670 newp = prev; 2671 newsize += nextsize + prevsize; 2672 newmem = chunk2mem(newp); 2673 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); 2674 goto split; 2675 } 2676 } 2677 2678 /* backward only */ 2679 if (prev != 0 && (long)(prevsize + newsize) >= (long)nb) 2680 { 2681 unlink(prev, bck, fwd); 2682 newp = prev; 2683 newsize += prevsize; 2684 newmem = chunk2mem(newp); 2685 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); 2686 goto split; 2687 } 2688 } 2689 2690 /* Must allocate */ 2691 2692 newmem = mALLOc (bytes); 2693 2694 if (newmem == 0) /* propagate failure */ 2695 return 0; 2696 2697 /* Avoid copy if newp is next chunk after oldp. */ 2698 /* (This can only happen when new chunk is sbrk'ed.) */ 2699 2700 if ( (newp = mem2chunk(newmem)) == next_chunk(oldp)) 2701 { 2702 newsize += chunksize(newp); 2703 newp = oldp; 2704 goto split; 2705 } 2706 2707 /* Otherwise copy, free, and exit */ 2708 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); 2709 fREe(oldmem); 2710 return newmem; 2711 } 2712 2713 2714 split: /* split off extra room in old or expanded chunk */ 2715 2716 if (newsize - nb >= MINSIZE) /* split off remainder */ 2717 { 2718 remainder = chunk_at_offset(newp, nb); 2719 remainder_size = newsize - nb; 2720 set_head_size(newp, nb); 2721 set_head(remainder, remainder_size | PREV_INUSE); 2722 set_inuse_bit_at_offset(remainder, remainder_size); 2723 fREe(chunk2mem(remainder)); /* let free() deal with it */ 2724 } 2725 else 2726 { 2727 set_head_size(newp, newsize); 2728 set_inuse_bit_at_offset(newp, newsize); 2729 } 2730 2731 check_inuse_chunk(newp); 2732 return chunk2mem(newp); 2733 } 2734 2735 2736 2737 2738 /* 2739 2740 memalign algorithm: 2741 2742 memalign requests more than enough space from malloc, finds a spot 2743 within that chunk that meets the alignment request, and then 2744 possibly frees the leading and trailing space. 2745 2746 The alignment argument must be a power of two. This property is not 2747 checked by memalign, so misuse may result in random runtime errors. 2748 2749 8-byte alignment is guaranteed by normal malloc calls, so don't 2750 bother calling memalign with an argument of 8 or less. 2751 2752 Overreliance on memalign is a sure way to fragment space. 2753 2754 */ 2755 2756 2757 #if __STD_C 2758 Void_t* mEMALIGn(size_t alignment, size_t bytes) 2759 #else 2760 Void_t* mEMALIGn(alignment, bytes) size_t alignment; size_t bytes; 2761 #endif 2762 { 2763 INTERNAL_SIZE_T nb; /* padded request size */ 2764 char* m; /* memory returned by malloc call */ 2765 mchunkptr p; /* corresponding chunk */ 2766 char* brk; /* alignment point within p */ 2767 mchunkptr newp; /* chunk to return */ 2768 INTERNAL_SIZE_T newsize; /* its size */ 2769 INTERNAL_SIZE_T leadsize; /* leading space befor alignment point */ 2770 mchunkptr remainder; /* spare room at end to split off */ 2771 long remainder_size; /* its size */ 2772 2773 if ((long)bytes < 0) return 0; 2774 2775 /* If need less alignment than we give anyway, just relay to malloc */ 2776 2777 if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes); 2778 2779 /* Otherwise, ensure that it is at least a minimum chunk size */ 2780 2781 if (alignment < MINSIZE) alignment = MINSIZE; 2782 2783 /* Call malloc with worst case padding to hit alignment. */ 2784 2785 nb = request2size(bytes); 2786 m = (char*)(mALLOc(nb + alignment + MINSIZE)); 2787 2788 if (m == 0) return 0; /* propagate failure */ 2789 2790 p = mem2chunk(m); 2791 2792 if ((((unsigned long)(m)) % alignment) == 0) /* aligned */ 2793 { 2794 #if HAVE_MMAP 2795 if(chunk_is_mmapped(p)) 2796 return chunk2mem(p); /* nothing more to do */ 2797 #endif 2798 } 2799 else /* misaligned */ 2800 { 2801 /* 2802 Find an aligned spot inside chunk. 2803 Since we need to give back leading space in a chunk of at 2804 least MINSIZE, if the first calculation places us at 2805 a spot with less than MINSIZE leader, we can move to the 2806 next aligned spot -- we've allocated enough total room so that 2807 this is always possible. 2808 */ 2809 2810 brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) & -((signed) alignment)); 2811 if ((long)(brk - (char*)(p)) < MINSIZE) brk = brk + alignment; 2812 2813 newp = (mchunkptr)brk; 2814 leadsize = brk - (char*)(p); 2815 newsize = chunksize(p) - leadsize; 2816 2817 #if HAVE_MMAP 2818 if(chunk_is_mmapped(p)) 2819 { 2820 newp->prev_size = p->prev_size + leadsize; 2821 set_head(newp, newsize|IS_MMAPPED); 2822 return chunk2mem(newp); 2823 } 2824 #endif 2825 2826 /* give back leader, use the rest */ 2827 2828 set_head(newp, newsize | PREV_INUSE); 2829 set_inuse_bit_at_offset(newp, newsize); 2830 set_head_size(p, leadsize); 2831 fREe(chunk2mem(p)); 2832 p = newp; 2833 2834 assert (newsize >= nb && (((unsigned long)(chunk2mem(p))) % alignment) == 0); 2835 } 2836 2837 /* Also give back spare room at the end */ 2838 2839 remainder_size = chunksize(p) - nb; 2840 2841 if (remainder_size >= (long)MINSIZE) 2842 { 2843 remainder = chunk_at_offset(p, nb); 2844 set_head(remainder, remainder_size | PREV_INUSE); 2845 set_head_size(p, nb); 2846 fREe(chunk2mem(remainder)); 2847 } 2848 2849 check_inuse_chunk(p); 2850 return chunk2mem(p); 2851 2852 } 2853 2854 2855 2856 2857 /* 2858 valloc just invokes memalign with alignment argument equal 2859 to the page size of the system (or as near to this as can 2860 be figured out from all the includes/defines above.) 2861 */ 2862 2863 #if __STD_C 2864 Void_t* vALLOc(size_t bytes) 2865 #else 2866 Void_t* vALLOc(bytes) size_t bytes; 2867 #endif 2868 { 2869 return mEMALIGn (malloc_getpagesize, bytes); 2870 } 2871 2872 /* 2873 pvalloc just invokes valloc for the nearest pagesize 2874 that will accommodate request 2875 */ 2876 2877 2878 #if __STD_C 2879 Void_t* pvALLOc(size_t bytes) 2880 #else 2881 Void_t* pvALLOc(bytes) size_t bytes; 2882 #endif 2883 { 2884 size_t pagesize = malloc_getpagesize; 2885 return mEMALIGn (pagesize, (bytes + pagesize - 1) & ~(pagesize - 1)); 2886 } 2887 2888 /* 2889 2890 calloc calls malloc, then zeroes out the allocated chunk. 2891 2892 */ 2893 2894 #if __STD_C 2895 Void_t* cALLOc(size_t n, size_t elem_size) 2896 #else 2897 Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size; 2898 #endif 2899 { 2900 mchunkptr p; 2901 INTERNAL_SIZE_T csz; 2902 2903 INTERNAL_SIZE_T sz = n * elem_size; 2904 2905 2906 /* check if expand_top called, in which case don't need to clear */ 2907 #if MORECORE_CLEARS 2908 mchunkptr oldtop = top; 2909 INTERNAL_SIZE_T oldtopsize = chunksize(top); 2910 #endif 2911 Void_t* mem = mALLOc (sz); 2912 2913 if ((long)n < 0) return 0; 2914 2915 if (mem == 0) 2916 return 0; 2917 else 2918 { 2919 p = mem2chunk(mem); 2920 2921 /* Two optional cases in which clearing not necessary */ 2922 2923 2924 #if HAVE_MMAP 2925 if (chunk_is_mmapped(p)) return mem; 2926 #endif 2927 2928 csz = chunksize(p); 2929 2930 #if MORECORE_CLEARS 2931 if (p == oldtop && csz > oldtopsize) 2932 { 2933 /* clear only the bytes from non-freshly-sbrked memory */ 2934 csz = oldtopsize; 2935 } 2936 #endif 2937 2938 MALLOC_ZERO(mem, csz - SIZE_SZ); 2939 return mem; 2940 } 2941 } 2942 2943 /* 2944 2945 cfree just calls free. It is needed/defined on some systems 2946 that pair it with calloc, presumably for odd historical reasons. 2947 2948 */ 2949 2950 #if !defined(INTERNAL_LINUX_C_LIB) || !defined(__ELF__) 2951 #if __STD_C 2952 void cfree(Void_t *mem) 2953 #else 2954 void cfree(mem) Void_t *mem; 2955 #endif 2956 { 2957 fREe(mem); 2958 } 2959 #endif 2960 2961 2962 2963 /* 2964 2965 Malloc_trim gives memory back to the system (via negative 2966 arguments to sbrk) if there is unused memory at the `high' end of 2967 the malloc pool. You can call this after freeing large blocks of 2968 memory to potentially reduce the system-level memory requirements 2969 of a program. However, it cannot guarantee to reduce memory. Under 2970 some allocation patterns, some large free blocks of memory will be 2971 locked between two used chunks, so they cannot be given back to 2972 the system. 2973 2974 The `pad' argument to malloc_trim represents the amount of free 2975 trailing space to leave untrimmed. If this argument is zero, 2976 only the minimum amount of memory to maintain internal data 2977 structures will be left (one page or less). Non-zero arguments 2978 can be supplied to maintain enough trailing space to service 2979 future expected allocations without having to re-obtain memory 2980 from the system. 2981 2982 Malloc_trim returns 1 if it actually released any memory, else 0. 2983 2984 */ 2985 2986 #if __STD_C 2987 int malloc_trim(size_t pad) 2988 #else 2989 int malloc_trim(pad) size_t pad; 2990 #endif 2991 { 2992 long top_size; /* Amount of top-most memory */ 2993 long extra; /* Amount to release */ 2994 char* current_brk; /* address returned by pre-check sbrk call */ 2995 char* new_brk; /* address returned by negative sbrk call */ 2996 2997 unsigned long pagesz = malloc_getpagesize; 2998 2999 top_size = chunksize(top); 3000 extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz; 3001 3002 if (extra < (long)pagesz) /* Not enough memory to release */ 3003 return 0; 3004 3005 else 3006 { 3007 /* Test to make sure no one else called sbrk */ 3008 current_brk = (char*)(MORECORE (0)); 3009 if (current_brk != (char*)(top) + top_size) 3010 return 0; /* Apparently we don't own memory; must fail */ 3011 3012 else 3013 { 3014 new_brk = (char*)(MORECORE (-extra)); 3015 3016 if (new_brk == (char*)(MORECORE_FAILURE)) /* sbrk failed? */ 3017 { 3018 /* Try to figure out what we have */ 3019 current_brk = (char*)(MORECORE (0)); 3020 top_size = current_brk - (char*)top; 3021 if (top_size >= (long)MINSIZE) /* if not, we are very very dead! */ 3022 { 3023 sbrked_mem = current_brk - sbrk_base; 3024 set_head(top, top_size | PREV_INUSE); 3025 } 3026 check_chunk(top); 3027 return 0; 3028 } 3029 3030 else 3031 { 3032 /* Success. Adjust top accordingly. */ 3033 set_head(top, (top_size - extra) | PREV_INUSE); 3034 sbrked_mem -= extra; 3035 check_chunk(top); 3036 return 1; 3037 } 3038 } 3039 } 3040 } 3041 3042 3043 3044 /* 3045 malloc_usable_size: 3046 3047 This routine tells you how many bytes you can actually use in an 3048 allocated chunk, which may be more than you requested (although 3049 often not). You can use this many bytes without worrying about 3050 overwriting other allocated objects. Not a particularly great 3051 programming practice, but still sometimes useful. 3052 3053 */ 3054 3055 #if __STD_C 3056 size_t malloc_usable_size(Void_t* mem) 3057 #else 3058 size_t malloc_usable_size(mem) Void_t* mem; 3059 #endif 3060 { 3061 mchunkptr p; 3062 if (mem == 0) 3063 return 0; 3064 else 3065 { 3066 p = mem2chunk(mem); 3067 if(!chunk_is_mmapped(p)) 3068 { 3069 if (!inuse(p)) return 0; 3070 check_inuse_chunk(p); 3071 return chunksize(p) - SIZE_SZ; 3072 } 3073 return chunksize(p) - 2*SIZE_SZ; 3074 } 3075 } 3076 3077 3078 3079 3080 /* Utility to update current_mallinfo for malloc_stats and mallinfo() */ 3081 3082 #if 0 3083 static void malloc_update_mallinfo() 3084 { 3085 int i; 3086 mbinptr b; 3087 mchunkptr p; 3088 #ifdef DEBUG 3089 mchunkptr q; 3090 #endif 3091 3092 INTERNAL_SIZE_T avail = chunksize(top); 3093 int navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0; 3094 3095 for (i = 1; i < NAV; ++i) 3096 { 3097 b = bin_at(i); 3098 for (p = last(b); p != b; p = p->bk) 3099 { 3100 #ifdef DEBUG 3101 check_free_chunk(p); 3102 for (q = next_chunk(p); 3103 q < top && inuse(q) && (long)(chunksize(q)) >= (long)MINSIZE; 3104 q = next_chunk(q)) 3105 check_inuse_chunk(q); 3106 #endif 3107 avail += chunksize(p); 3108 navail++; 3109 } 3110 } 3111 3112 current_mallinfo.ordblks = navail; 3113 current_mallinfo.uordblks = sbrked_mem - avail; 3114 current_mallinfo.fordblks = avail; 3115 current_mallinfo.hblks = n_mmaps; 3116 current_mallinfo.hblkhd = mmapped_mem; 3117 current_mallinfo.keepcost = chunksize(top); 3118 3119 } 3120 #endif /* 0 */ 3121 3122 3123 3124 /* 3125 3126 malloc_stats: 3127 3128 Prints on the amount of space obtain from the system (both 3129 via sbrk and mmap), the maximum amount (which may be more than 3130 current if malloc_trim and/or munmap got called), the maximum 3131 number of simultaneous mmap regions used, and the current number 3132 of bytes allocated via malloc (or realloc, etc) but not yet 3133 freed. (Note that this is the number of bytes allocated, not the 3134 number requested. It will be larger than the number requested 3135 because of alignment and bookkeeping overhead.) 3136 3137 */ 3138 3139 #if 0 3140 void malloc_stats() 3141 { 3142 malloc_update_mallinfo(); 3143 printf("max system bytes = %10u\n", 3144 (unsigned int)(max_total_mem)); 3145 printf("system bytes = %10u\n", 3146 (unsigned int)(sbrked_mem + mmapped_mem)); 3147 printf("in use bytes = %10u\n", 3148 (unsigned int)(current_mallinfo.uordblks + mmapped_mem)); 3149 #if HAVE_MMAP 3150 printf("max mmap regions = %10u\n", 3151 (unsigned int)max_n_mmaps); 3152 #endif 3153 } 3154 #endif /* 0 */ 3155 3156 /* 3157 mallinfo returns a copy of updated current mallinfo. 3158 */ 3159 3160 #if 0 3161 struct mallinfo mALLINFo() 3162 { 3163 malloc_update_mallinfo(); 3164 return current_mallinfo; 3165 } 3166 #endif /* 0 */ 3167 3168 3169 3170 3171 /* 3172 mallopt: 3173 3174 mallopt is the general SVID/XPG interface to tunable parameters. 3175 The format is to provide a (parameter-number, parameter-value) pair. 3176 mallopt then sets the corresponding parameter to the argument 3177 value if it can (i.e., so long as the value is meaningful), 3178 and returns 1 if successful else 0. 3179 3180 See descriptions of tunable parameters above. 3181 3182 */ 3183 3184 #if __STD_C 3185 int mALLOPt(int param_number, int value) 3186 #else 3187 int mALLOPt(param_number, value) int param_number; int value; 3188 #endif 3189 { 3190 switch(param_number) 3191 { 3192 case M_TRIM_THRESHOLD: 3193 trim_threshold = value; return 1; 3194 case M_TOP_PAD: 3195 top_pad = value; return 1; 3196 case M_MMAP_THRESHOLD: 3197 mmap_threshold = value; return 1; 3198 case M_MMAP_MAX: 3199 #if HAVE_MMAP 3200 n_mmaps_max = value; return 1; 3201 #else 3202 if (value != 0) return 0; else n_mmaps_max = value; return 1; 3203 #endif 3204 3205 default: 3206 return 0; 3207 } 3208 } 3209 3210 /* 3211 3212 History: 3213 3214 V2.6.6 Sun Dec 5 07:42:19 1999 Doug Lea (dl at gee) 3215 * return null for negative arguments 3216 * Added Several WIN32 cleanups from Martin C. Fong <mcfong@yahoo.com> 3217 * Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h' 3218 (e.g. WIN32 platforms) 3219 * Cleanup up header file inclusion for WIN32 platforms 3220 * Cleanup code to avoid Microsoft Visual C++ compiler complaints 3221 * Add 'USE_DL_PREFIX' to quickly allow co-existence with existing 3222 memory allocation routines 3223 * Set 'malloc_getpagesize' for WIN32 platforms (needs more work) 3224 * Use 'assert' rather than 'ASSERT' in WIN32 code to conform to 3225 usage of 'assert' in non-WIN32 code 3226 * Improve WIN32 'sbrk()' emulation's 'findRegion()' routine to 3227 avoid infinite loop 3228 * Always call 'fREe()' rather than 'free()' 3229 3230 V2.6.5 Wed Jun 17 15:57:31 1998 Doug Lea (dl at gee) 3231 * Fixed ordering problem with boundary-stamping 3232 3233 V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee) 3234 * Added pvalloc, as recommended by H.J. Liu 3235 * Added 64bit pointer support mainly from Wolfram Gloger 3236 * Added anonymously donated WIN32 sbrk emulation 3237 * Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen 3238 * malloc_extend_top: fix mask error that caused wastage after 3239 foreign sbrks 3240 * Add linux mremap support code from HJ Liu 3241 3242 V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee) 3243 * Integrated most documentation with the code. 3244 * Add support for mmap, with help from 3245 Wolfram Gloger (Gloger@lrz.uni-muenchen.de). 3246 * Use last_remainder in more cases. 3247 * Pack bins using idea from colin@nyx10.cs.du.edu 3248 * Use ordered bins instead of best-fit threshhold 3249 * Eliminate block-local decls to simplify tracing and debugging. 3250 * Support another case of realloc via move into top 3251 * Fix error occuring when initial sbrk_base not word-aligned. 3252 * Rely on page size for units instead of SBRK_UNIT to 3253 avoid surprises about sbrk alignment conventions. 3254 * Add mallinfo, mallopt. Thanks to Raymond Nijssen 3255 (raymond@es.ele.tue.nl) for the suggestion. 3256 * Add `pad' argument to malloc_trim and top_pad mallopt parameter. 3257 * More precautions for cases where other routines call sbrk, 3258 courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de). 3259 * Added macros etc., allowing use in linux libc from 3260 H.J. Lu (hjl@gnu.ai.mit.edu) 3261 * Inverted this history list 3262 3263 V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee) 3264 * Re-tuned and fixed to behave more nicely with V2.6.0 changes. 3265 * Removed all preallocation code since under current scheme 3266 the work required to undo bad preallocations exceeds 3267 the work saved in good cases for most test programs. 3268 * No longer use return list or unconsolidated bins since 3269 no scheme using them consistently outperforms those that don't 3270 given above changes. 3271 * Use best fit for very large chunks to prevent some worst-cases. 3272 * Added some support for debugging 3273 3274 V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee) 3275 * Removed footers when chunks are in use. Thanks to 3276 Paul Wilson (wilson@cs.texas.edu) for the suggestion. 3277 3278 V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee) 3279 * Added malloc_trim, with help from Wolfram Gloger 3280 (wmglo@Dent.MED.Uni-Muenchen.DE). 3281 3282 V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g) 3283 3284 V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g) 3285 * realloc: try to expand in both directions 3286 * malloc: swap order of clean-bin strategy; 3287 * realloc: only conditionally expand backwards 3288 * Try not to scavenge used bins 3289 * Use bin counts as a guide to preallocation 3290 * Occasionally bin return list chunks in first scan 3291 * Add a few optimizations from colin@nyx10.cs.du.edu 3292 3293 V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g) 3294 * faster bin computation & slightly different binning 3295 * merged all consolidations to one part of malloc proper 3296 (eliminating old malloc_find_space & malloc_clean_bin) 3297 * Scan 2 returns chunks (not just 1) 3298 * Propagate failure in realloc if malloc returns 0 3299 * Add stuff to allow compilation on non-ANSI compilers 3300 from kpv@research.att.com 3301 3302 V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu) 3303 * removed potential for odd address access in prev_chunk 3304 * removed dependency on getpagesize.h 3305 * misc cosmetics and a bit more internal documentation 3306 * anticosmetics: mangled names in macros to evade debugger strangeness 3307 * tested on sparc, hp-700, dec-mips, rs6000 3308 with gcc & native cc (hp, dec only) allowing 3309 Detlefs & Zorn comparison study (in SIGPLAN Notices.) 3310 3311 Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu) 3312 * Based loosely on libg++-1.2X malloc. (It retains some of the overall 3313 structure of old version, but most details differ.) 3314 3315 */ 3316 3317 3318