1 #include <common.h> 2 3 #if 0 /* Moved to malloc.h */ 4 /* ---------- To make a malloc.h, start cutting here ------------ */ 5 6 /* 7 A version of malloc/free/realloc written by Doug Lea and released to the 8 public domain. Send questions/comments/complaints/performance data 9 to dl@cs.oswego.edu 10 11 * VERSION 2.6.6 Sun Mar 5 19:10:03 2000 Doug Lea (dl at gee) 12 13 Note: There may be an updated version of this malloc obtainable at 14 ftp://g.oswego.edu/pub/misc/malloc.c 15 Check before installing! 16 17 * Why use this malloc? 18 19 This is not the fastest, most space-conserving, most portable, or 20 most tunable malloc ever written. However it is among the fastest 21 while also being among the most space-conserving, portable and tunable. 22 Consistent balance across these factors results in a good general-purpose 23 allocator. For a high-level description, see 24 http://g.oswego.edu/dl/html/malloc.html 25 26 * Synopsis of public routines 27 28 (Much fuller descriptions are contained in the program documentation below.) 29 30 malloc(size_t n); 31 Return a pointer to a newly allocated chunk of at least n bytes, or null 32 if no space is available. 33 free(Void_t* p); 34 Release the chunk of memory pointed to by p, or no effect if p is null. 35 realloc(Void_t* p, size_t n); 36 Return a pointer to a chunk of size n that contains the same data 37 as does chunk p up to the minimum of (n, p's size) bytes, or null 38 if no space is available. The returned pointer may or may not be 39 the same as p. If p is null, equivalent to malloc. Unless the 40 #define REALLOC_ZERO_BYTES_FREES below is set, realloc with a 41 size argument of zero (re)allocates a minimum-sized chunk. 42 memalign(size_t alignment, size_t n); 43 Return a pointer to a newly allocated chunk of n bytes, aligned 44 in accord with the alignment argument, which must be a power of 45 two. 46 valloc(size_t n); 47 Equivalent to memalign(pagesize, n), where pagesize is the page 48 size of the system (or as near to this as can be figured out from 49 all the includes/defines below.) 50 pvalloc(size_t n); 51 Equivalent to valloc(minimum-page-that-holds(n)), that is, 52 round up n to nearest pagesize. 53 calloc(size_t unit, size_t quantity); 54 Returns a pointer to quantity * unit bytes, with all locations 55 set to zero. 56 cfree(Void_t* p); 57 Equivalent to free(p). 58 malloc_trim(size_t pad); 59 Release all but pad bytes of freed top-most memory back 60 to the system. Return 1 if successful, else 0. 61 malloc_usable_size(Void_t* p); 62 Report the number usable allocated bytes associated with allocated 63 chunk p. This may or may not report more bytes than were requested, 64 due to alignment and minimum size constraints. 65 malloc_stats(); 66 Prints brief summary statistics. 67 mallinfo() 68 Returns (by copy) a struct containing various summary statistics. 69 mallopt(int parameter_number, int parameter_value) 70 Changes one of the tunable parameters described below. Returns 71 1 if successful in changing the parameter, else 0. 72 73 * Vital statistics: 74 75 Alignment: 8-byte 76 8 byte alignment is currently hardwired into the design. This 77 seems to suffice for all current machines and C compilers. 78 79 Assumed pointer representation: 4 or 8 bytes 80 Code for 8-byte pointers is untested by me but has worked 81 reliably by Wolfram Gloger, who contributed most of the 82 changes supporting this. 83 84 Assumed size_t representation: 4 or 8 bytes 85 Note that size_t is allowed to be 4 bytes even if pointers are 8. 86 87 Minimum overhead per allocated chunk: 4 or 8 bytes 88 Each malloced chunk has a hidden overhead of 4 bytes holding size 89 and status information. 90 91 Minimum allocated size: 4-byte ptrs: 16 bytes (including 4 overhead) 92 8-byte ptrs: 24/32 bytes (including, 4/8 overhead) 93 94 When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte 95 ptrs but 4 byte size) or 24 (for 8/8) additional bytes are 96 needed; 4 (8) for a trailing size field 97 and 8 (16) bytes for free list pointers. Thus, the minimum 98 allocatable size is 16/24/32 bytes. 99 100 Even a request for zero bytes (i.e., malloc(0)) returns a 101 pointer to something of the minimum allocatable size. 102 103 Maximum allocated size: 4-byte size_t: 2^31 - 8 bytes 104 8-byte size_t: 2^63 - 16 bytes 105 106 It is assumed that (possibly signed) size_t bit values suffice to 107 represent chunk sizes. `Possibly signed' is due to the fact 108 that `size_t' may be defined on a system as either a signed or 109 an unsigned type. To be conservative, values that would appear 110 as negative numbers are avoided. 111 Requests for sizes with a negative sign bit when the request 112 size is treaded as a long will return null. 113 114 Maximum overhead wastage per allocated chunk: normally 15 bytes 115 116 Alignnment demands, plus the minimum allocatable size restriction 117 make the normal worst-case wastage 15 bytes (i.e., up to 15 118 more bytes will be allocated than were requested in malloc), with 119 two exceptions: 120 1. Because requests for zero bytes allocate non-zero space, 121 the worst case wastage for a request of zero bytes is 24 bytes. 122 2. For requests >= mmap_threshold that are serviced via 123 mmap(), the worst case wastage is 8 bytes plus the remainder 124 from a system page (the minimal mmap unit); typically 4096 bytes. 125 126 * Limitations 127 128 Here are some features that are NOT currently supported 129 130 * No user-definable hooks for callbacks and the like. 131 * No automated mechanism for fully checking that all accesses 132 to malloced memory stay within their bounds. 133 * No support for compaction. 134 135 * Synopsis of compile-time options: 136 137 People have reported using previous versions of this malloc on all 138 versions of Unix, sometimes by tweaking some of the defines 139 below. It has been tested most extensively on Solaris and 140 Linux. It is also reported to work on WIN32 platforms. 141 People have also reported adapting this malloc for use in 142 stand-alone embedded systems. 143 144 The implementation is in straight, hand-tuned ANSI C. Among other 145 consequences, it uses a lot of macros. Because of this, to be at 146 all usable, this code should be compiled using an optimizing compiler 147 (for example gcc -O2) that can simplify expressions and control 148 paths. 149 150 __STD_C (default: derived from C compiler defines) 151 Nonzero if using ANSI-standard C compiler, a C++ compiler, or 152 a C compiler sufficiently close to ANSI to get away with it. 153 DEBUG (default: NOT defined) 154 Define to enable debugging. Adds fairly extensive assertion-based 155 checking to help track down memory errors, but noticeably slows down 156 execution. 157 REALLOC_ZERO_BYTES_FREES (default: NOT defined) 158 Define this if you think that realloc(p, 0) should be equivalent 159 to free(p). Otherwise, since malloc returns a unique pointer for 160 malloc(0), so does realloc(p, 0). 161 HAVE_MEMCPY (default: defined) 162 Define if you are not otherwise using ANSI STD C, but still 163 have memcpy and memset in your C library and want to use them. 164 Otherwise, simple internal versions are supplied. 165 USE_MEMCPY (default: 1 if HAVE_MEMCPY is defined, 0 otherwise) 166 Define as 1 if you want the C library versions of memset and 167 memcpy called in realloc and calloc (otherwise macro versions are used). 168 At least on some platforms, the simple macro versions usually 169 outperform libc versions. 170 HAVE_MMAP (default: defined as 1) 171 Define to non-zero to optionally make malloc() use mmap() to 172 allocate very large blocks. 173 HAVE_MREMAP (default: defined as 0 unless Linux libc set) 174 Define to non-zero to optionally make realloc() use mremap() to 175 reallocate very large blocks. 176 malloc_getpagesize (default: derived from system #includes) 177 Either a constant or routine call returning the system page size. 178 HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined) 179 Optionally define if you are on a system with a /usr/include/malloc.h 180 that declares struct mallinfo. It is not at all necessary to 181 define this even if you do, but will ensure consistency. 182 INTERNAL_SIZE_T (default: size_t) 183 Define to a 32-bit type (probably `unsigned int') if you are on a 184 64-bit machine, yet do not want or need to allow malloc requests of 185 greater than 2^31 to be handled. This saves space, especially for 186 very small chunks. 187 INTERNAL_LINUX_C_LIB (default: NOT defined) 188 Defined only when compiled as part of Linux libc. 189 Also note that there is some odd internal name-mangling via defines 190 (for example, internally, `malloc' is named `mALLOc') needed 191 when compiling in this case. These look funny but don't otherwise 192 affect anything. 193 WIN32 (default: undefined) 194 Define this on MS win (95, nt) platforms to compile in sbrk emulation. 195 LACKS_UNISTD_H (default: undefined if not WIN32) 196 Define this if your system does not have a <unistd.h>. 197 LACKS_SYS_PARAM_H (default: undefined if not WIN32) 198 Define this if your system does not have a <sys/param.h>. 199 MORECORE (default: sbrk) 200 The name of the routine to call to obtain more memory from the system. 201 MORECORE_FAILURE (default: -1) 202 The value returned upon failure of MORECORE. 203 MORECORE_CLEARS (default 1) 204 true (1) if the routine mapped to MORECORE zeroes out memory (which 205 holds for sbrk). 206 DEFAULT_TRIM_THRESHOLD 207 DEFAULT_TOP_PAD 208 DEFAULT_MMAP_THRESHOLD 209 DEFAULT_MMAP_MAX 210 Default values of tunable parameters (described in detail below) 211 controlling interaction with host system routines (sbrk, mmap, etc). 212 These values may also be changed dynamically via mallopt(). The 213 preset defaults are those that give best performance for typical 214 programs/systems. 215 USE_DL_PREFIX (default: undefined) 216 Prefix all public routines with the string 'dl'. Useful to 217 quickly avoid procedure declaration conflicts and linker symbol 218 conflicts with existing memory allocation routines. 219 220 221 */ 222 223 224 225 /* Preliminaries */ 226 227 #ifndef __STD_C 228 #ifdef __STDC__ 229 #define __STD_C 1 230 #else 231 #if __cplusplus 232 #define __STD_C 1 233 #else 234 #define __STD_C 0 235 #endif /*__cplusplus*/ 236 #endif /*__STDC__*/ 237 #endif /*__STD_C*/ 238 239 #ifndef Void_t 240 #if (__STD_C || defined(WIN32)) 241 #define Void_t void 242 #else 243 #define Void_t char 244 #endif 245 #endif /*Void_t*/ 246 247 #if __STD_C 248 #include <stddef.h> /* for size_t */ 249 #else 250 #include <sys/types.h> 251 #endif 252 253 #ifdef __cplusplus 254 extern "C" { 255 #endif 256 257 #include <stdio.h> /* needed for malloc_stats */ 258 259 260 /* 261 Compile-time options 262 */ 263 264 265 /* 266 Debugging: 267 268 Because freed chunks may be overwritten with link fields, this 269 malloc will often die when freed memory is overwritten by user 270 programs. This can be very effective (albeit in an annoying way) 271 in helping track down dangling pointers. 272 273 If you compile with -DDEBUG, a number of assertion checks are 274 enabled that will catch more memory errors. You probably won't be 275 able to make much sense of the actual assertion errors, but they 276 should help you locate incorrectly overwritten memory. The 277 checking is fairly extensive, and will slow down execution 278 noticeably. Calling malloc_stats or mallinfo with DEBUG set will 279 attempt to check every non-mmapped allocated and free chunk in the 280 course of computing the summmaries. (By nature, mmapped regions 281 cannot be checked very much automatically.) 282 283 Setting DEBUG may also be helpful if you are trying to modify 284 this code. The assertions in the check routines spell out in more 285 detail the assumptions and invariants underlying the algorithms. 286 287 */ 288 289 /* 290 INTERNAL_SIZE_T is the word-size used for internal bookkeeping 291 of chunk sizes. On a 64-bit machine, you can reduce malloc 292 overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int' 293 at the expense of not being able to handle requests greater than 294 2^31. This limitation is hardly ever a concern; you are encouraged 295 to set this. However, the default version is the same as size_t. 296 */ 297 298 #ifndef INTERNAL_SIZE_T 299 #define INTERNAL_SIZE_T size_t 300 #endif 301 302 /* 303 REALLOC_ZERO_BYTES_FREES should be set if a call to 304 realloc with zero bytes should be the same as a call to free. 305 Some people think it should. Otherwise, since this malloc 306 returns a unique pointer for malloc(0), so does realloc(p, 0). 307 */ 308 309 310 /* #define REALLOC_ZERO_BYTES_FREES */ 311 312 313 /* 314 WIN32 causes an emulation of sbrk to be compiled in 315 mmap-based options are not currently supported in WIN32. 316 */ 317 318 /* #define WIN32 */ 319 #ifdef WIN32 320 #define MORECORE wsbrk 321 #define HAVE_MMAP 0 322 323 #define LACKS_UNISTD_H 324 #define LACKS_SYS_PARAM_H 325 326 /* 327 Include 'windows.h' to get the necessary declarations for the 328 Microsoft Visual C++ data structures and routines used in the 'sbrk' 329 emulation. 330 331 Define WIN32_LEAN_AND_MEAN so that only the essential Microsoft 332 Visual C++ header files are included. 333 */ 334 #define WIN32_LEAN_AND_MEAN 335 #include <windows.h> 336 #endif 337 338 339 /* 340 HAVE_MEMCPY should be defined if you are not otherwise using 341 ANSI STD C, but still have memcpy and memset in your C library 342 and want to use them in calloc and realloc. Otherwise simple 343 macro versions are defined here. 344 345 USE_MEMCPY should be defined as 1 if you actually want to 346 have memset and memcpy called. People report that the macro 347 versions are often enough faster than libc versions on many 348 systems that it is better to use them. 349 350 */ 351 352 #define HAVE_MEMCPY 353 354 #ifndef USE_MEMCPY 355 #ifdef HAVE_MEMCPY 356 #define USE_MEMCPY 1 357 #else 358 #define USE_MEMCPY 0 359 #endif 360 #endif 361 362 #if (__STD_C || defined(HAVE_MEMCPY)) 363 364 #if __STD_C 365 void* memset(void*, int, size_t); 366 void* memcpy(void*, const void*, size_t); 367 #else 368 #ifdef WIN32 369 /* On Win32 platforms, 'memset()' and 'memcpy()' are already declared in */ 370 /* 'windows.h' */ 371 #else 372 Void_t* memset(); 373 Void_t* memcpy(); 374 #endif 375 #endif 376 #endif 377 378 #if USE_MEMCPY 379 380 /* The following macros are only invoked with (2n+1)-multiples of 381 INTERNAL_SIZE_T units, with a positive integer n. This is exploited 382 for fast inline execution when n is small. */ 383 384 #define MALLOC_ZERO(charp, nbytes) \ 385 do { \ 386 INTERNAL_SIZE_T mzsz = (nbytes); \ 387 if(mzsz <= 9*sizeof(mzsz)) { \ 388 INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp); \ 389 if(mzsz >= 5*sizeof(mzsz)) { *mz++ = 0; \ 390 *mz++ = 0; \ 391 if(mzsz >= 7*sizeof(mzsz)) { *mz++ = 0; \ 392 *mz++ = 0; \ 393 if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0; \ 394 *mz++ = 0; }}} \ 395 *mz++ = 0; \ 396 *mz++ = 0; \ 397 *mz = 0; \ 398 } else memset((charp), 0, mzsz); \ 399 } while(0) 400 401 #define MALLOC_COPY(dest,src,nbytes) \ 402 do { \ 403 INTERNAL_SIZE_T mcsz = (nbytes); \ 404 if(mcsz <= 9*sizeof(mcsz)) { \ 405 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src); \ 406 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest); \ 407 if(mcsz >= 5*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ 408 *mcdst++ = *mcsrc++; \ 409 if(mcsz >= 7*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ 410 *mcdst++ = *mcsrc++; \ 411 if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++; \ 412 *mcdst++ = *mcsrc++; }}} \ 413 *mcdst++ = *mcsrc++; \ 414 *mcdst++ = *mcsrc++; \ 415 *mcdst = *mcsrc ; \ 416 } else memcpy(dest, src, mcsz); \ 417 } while(0) 418 419 #else /* !USE_MEMCPY */ 420 421 /* Use Duff's device for good zeroing/copying performance. */ 422 423 #define MALLOC_ZERO(charp, nbytes) \ 424 do { \ 425 INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp); \ 426 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \ 427 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \ 428 switch (mctmp) { \ 429 case 0: for(;;) { *mzp++ = 0; \ 430 case 7: *mzp++ = 0; \ 431 case 6: *mzp++ = 0; \ 432 case 5: *mzp++ = 0; \ 433 case 4: *mzp++ = 0; \ 434 case 3: *mzp++ = 0; \ 435 case 2: *mzp++ = 0; \ 436 case 1: *mzp++ = 0; if(mcn <= 0) break; mcn--; } \ 437 } \ 438 } while(0) 439 440 #define MALLOC_COPY(dest,src,nbytes) \ 441 do { \ 442 INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src; \ 443 INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest; \ 444 long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn; \ 445 if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; } \ 446 switch (mctmp) { \ 447 case 0: for(;;) { *mcdst++ = *mcsrc++; \ 448 case 7: *mcdst++ = *mcsrc++; \ 449 case 6: *mcdst++ = *mcsrc++; \ 450 case 5: *mcdst++ = *mcsrc++; \ 451 case 4: *mcdst++ = *mcsrc++; \ 452 case 3: *mcdst++ = *mcsrc++; \ 453 case 2: *mcdst++ = *mcsrc++; \ 454 case 1: *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; } \ 455 } \ 456 } while(0) 457 458 #endif 459 460 461 /* 462 Define HAVE_MMAP to optionally make malloc() use mmap() to 463 allocate very large blocks. These will be returned to the 464 operating system immediately after a free(). 465 */ 466 467 #ifndef HAVE_MMAP 468 #define HAVE_MMAP 1 469 #endif 470 471 /* 472 Define HAVE_MREMAP to make realloc() use mremap() to re-allocate 473 large blocks. This is currently only possible on Linux with 474 kernel versions newer than 1.3.77. 475 */ 476 477 #ifndef HAVE_MREMAP 478 #ifdef INTERNAL_LINUX_C_LIB 479 #define HAVE_MREMAP 1 480 #else 481 #define HAVE_MREMAP 0 482 #endif 483 #endif 484 485 #if HAVE_MMAP 486 487 #include <unistd.h> 488 #include <fcntl.h> 489 #include <sys/mman.h> 490 491 #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON) 492 #define MAP_ANONYMOUS MAP_ANON 493 #endif 494 495 #endif /* HAVE_MMAP */ 496 497 /* 498 Access to system page size. To the extent possible, this malloc 499 manages memory from the system in page-size units. 500 501 The following mechanics for getpagesize were adapted from 502 bsd/gnu getpagesize.h 503 */ 504 505 #ifndef LACKS_UNISTD_H 506 # include <unistd.h> 507 #endif 508 509 #ifndef malloc_getpagesize 510 # ifdef _SC_PAGESIZE /* some SVR4 systems omit an underscore */ 511 # ifndef _SC_PAGE_SIZE 512 # define _SC_PAGE_SIZE _SC_PAGESIZE 513 # endif 514 # endif 515 # ifdef _SC_PAGE_SIZE 516 # define malloc_getpagesize sysconf(_SC_PAGE_SIZE) 517 # else 518 # if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE) 519 extern size_t getpagesize(); 520 # define malloc_getpagesize getpagesize() 521 # else 522 # ifdef WIN32 523 # define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */ 524 # else 525 # ifndef LACKS_SYS_PARAM_H 526 # include <sys/param.h> 527 # endif 528 # ifdef EXEC_PAGESIZE 529 # define malloc_getpagesize EXEC_PAGESIZE 530 # else 531 # ifdef NBPG 532 # ifndef CLSIZE 533 # define malloc_getpagesize NBPG 534 # else 535 # define malloc_getpagesize (NBPG * CLSIZE) 536 # endif 537 # else 538 # ifdef NBPC 539 # define malloc_getpagesize NBPC 540 # else 541 # ifdef PAGESIZE 542 # define malloc_getpagesize PAGESIZE 543 # else 544 # define malloc_getpagesize (4096) /* just guess */ 545 # endif 546 # endif 547 # endif 548 # endif 549 # endif 550 # endif 551 # endif 552 #endif 553 554 555 /* 556 557 This version of malloc supports the standard SVID/XPG mallinfo 558 routine that returns a struct containing the same kind of 559 information you can get from malloc_stats. It should work on 560 any SVID/XPG compliant system that has a /usr/include/malloc.h 561 defining struct mallinfo. (If you'd like to install such a thing 562 yourself, cut out the preliminary declarations as described above 563 and below and save them in a malloc.h file. But there's no 564 compelling reason to bother to do this.) 565 566 The main declaration needed is the mallinfo struct that is returned 567 (by-copy) by mallinfo(). The SVID/XPG malloinfo struct contains a 568 bunch of fields, most of which are not even meaningful in this 569 version of malloc. Some of these fields are are instead filled by 570 mallinfo() with other numbers that might possibly be of interest. 571 572 HAVE_USR_INCLUDE_MALLOC_H should be set if you have a 573 /usr/include/malloc.h file that includes a declaration of struct 574 mallinfo. If so, it is included; else an SVID2/XPG2 compliant 575 version is declared below. These must be precisely the same for 576 mallinfo() to work. 577 578 */ 579 580 /* #define HAVE_USR_INCLUDE_MALLOC_H */ 581 582 #if HAVE_USR_INCLUDE_MALLOC_H 583 #include "/usr/include/malloc.h" 584 #else 585 586 /* SVID2/XPG mallinfo structure */ 587 588 struct mallinfo { 589 int arena; /* total space allocated from system */ 590 int ordblks; /* number of non-inuse chunks */ 591 int smblks; /* unused -- always zero */ 592 int hblks; /* number of mmapped regions */ 593 int hblkhd; /* total space in mmapped regions */ 594 int usmblks; /* unused -- always zero */ 595 int fsmblks; /* unused -- always zero */ 596 int uordblks; /* total allocated space */ 597 int fordblks; /* total non-inuse space */ 598 int keepcost; /* top-most, releasable (via malloc_trim) space */ 599 }; 600 601 /* SVID2/XPG mallopt options */ 602 603 #define M_MXFAST 1 /* UNUSED in this malloc */ 604 #define M_NLBLKS 2 /* UNUSED in this malloc */ 605 #define M_GRAIN 3 /* UNUSED in this malloc */ 606 #define M_KEEP 4 /* UNUSED in this malloc */ 607 608 #endif 609 610 /* mallopt options that actually do something */ 611 612 #define M_TRIM_THRESHOLD -1 613 #define M_TOP_PAD -2 614 #define M_MMAP_THRESHOLD -3 615 #define M_MMAP_MAX -4 616 617 618 #ifndef DEFAULT_TRIM_THRESHOLD 619 #define DEFAULT_TRIM_THRESHOLD (128 * 1024) 620 #endif 621 622 /* 623 M_TRIM_THRESHOLD is the maximum amount of unused top-most memory 624 to keep before releasing via malloc_trim in free(). 625 626 Automatic trimming is mainly useful in long-lived programs. 627 Because trimming via sbrk can be slow on some systems, and can 628 sometimes be wasteful (in cases where programs immediately 629 afterward allocate more large chunks) the value should be high 630 enough so that your overall system performance would improve by 631 releasing. 632 633 The trim threshold and the mmap control parameters (see below) 634 can be traded off with one another. Trimming and mmapping are 635 two different ways of releasing unused memory back to the 636 system. Between these two, it is often possible to keep 637 system-level demands of a long-lived program down to a bare 638 minimum. For example, in one test suite of sessions measuring 639 the XF86 X server on Linux, using a trim threshold of 128K and a 640 mmap threshold of 192K led to near-minimal long term resource 641 consumption. 642 643 If you are using this malloc in a long-lived program, it should 644 pay to experiment with these values. As a rough guide, you 645 might set to a value close to the average size of a process 646 (program) running on your system. Releasing this much memory 647 would allow such a process to run in memory. Generally, it's 648 worth it to tune for trimming rather tham memory mapping when a 649 program undergoes phases where several large chunks are 650 allocated and released in ways that can reuse each other's 651 storage, perhaps mixed with phases where there are no such 652 chunks at all. And in well-behaved long-lived programs, 653 controlling release of large blocks via trimming versus mapping 654 is usually faster. 655 656 However, in most programs, these parameters serve mainly as 657 protection against the system-level effects of carrying around 658 massive amounts of unneeded memory. Since frequent calls to 659 sbrk, mmap, and munmap otherwise degrade performance, the default 660 parameters are set to relatively high values that serve only as 661 safeguards. 662 663 The default trim value is high enough to cause trimming only in 664 fairly extreme (by current memory consumption standards) cases. 665 It must be greater than page size to have any useful effect. To 666 disable trimming completely, you can set to (unsigned long)(-1); 667 668 669 */ 670 671 672 #ifndef DEFAULT_TOP_PAD 673 #define DEFAULT_TOP_PAD (0) 674 #endif 675 676 /* 677 M_TOP_PAD is the amount of extra `padding' space to allocate or 678 retain whenever sbrk is called. It is used in two ways internally: 679 680 * When sbrk is called to extend the top of the arena to satisfy 681 a new malloc request, this much padding is added to the sbrk 682 request. 683 684 * When malloc_trim is called automatically from free(), 685 it is used as the `pad' argument. 686 687 In both cases, the actual amount of padding is rounded 688 so that the end of the arena is always a system page boundary. 689 690 The main reason for using padding is to avoid calling sbrk so 691 often. Having even a small pad greatly reduces the likelihood 692 that nearly every malloc request during program start-up (or 693 after trimming) will invoke sbrk, which needlessly wastes 694 time. 695 696 Automatic rounding-up to page-size units is normally sufficient 697 to avoid measurable overhead, so the default is 0. However, in 698 systems where sbrk is relatively slow, it can pay to increase 699 this value, at the expense of carrying around more memory than 700 the program needs. 701 702 */ 703 704 705 #ifndef DEFAULT_MMAP_THRESHOLD 706 #define DEFAULT_MMAP_THRESHOLD (128 * 1024) 707 #endif 708 709 /* 710 711 M_MMAP_THRESHOLD is the request size threshold for using mmap() 712 to service a request. Requests of at least this size that cannot 713 be allocated using already-existing space will be serviced via mmap. 714 (If enough normal freed space already exists it is used instead.) 715 716 Using mmap segregates relatively large chunks of memory so that 717 they can be individually obtained and released from the host 718 system. A request serviced through mmap is never reused by any 719 other request (at least not directly; the system may just so 720 happen to remap successive requests to the same locations). 721 722 Segregating space in this way has the benefit that mmapped space 723 can ALWAYS be individually released back to the system, which 724 helps keep the system level memory demands of a long-lived 725 program low. Mapped memory can never become `locked' between 726 other chunks, as can happen with normally allocated chunks, which 727 menas that even trimming via malloc_trim would not release them. 728 729 However, it has the disadvantages that: 730 731 1. The space cannot be reclaimed, consolidated, and then 732 used to service later requests, as happens with normal chunks. 733 2. It can lead to more wastage because of mmap page alignment 734 requirements 735 3. It causes malloc performance to be more dependent on host 736 system memory management support routines which may vary in 737 implementation quality and may impose arbitrary 738 limitations. Generally, servicing a request via normal 739 malloc steps is faster than going through a system's mmap. 740 741 All together, these considerations should lead you to use mmap 742 only for relatively large requests. 743 744 745 */ 746 747 748 #ifndef DEFAULT_MMAP_MAX 749 #if HAVE_MMAP 750 #define DEFAULT_MMAP_MAX (64) 751 #else 752 #define DEFAULT_MMAP_MAX (0) 753 #endif 754 #endif 755 756 /* 757 M_MMAP_MAX is the maximum number of requests to simultaneously 758 service using mmap. This parameter exists because: 759 760 1. Some systems have a limited number of internal tables for 761 use by mmap. 762 2. In most systems, overreliance on mmap can degrade overall 763 performance. 764 3. If a program allocates many large regions, it is probably 765 better off using normal sbrk-based allocation routines that 766 can reclaim and reallocate normal heap memory. Using a 767 small value allows transition into this mode after the 768 first few allocations. 769 770 Setting to 0 disables all use of mmap. If HAVE_MMAP is not set, 771 the default value is 0, and attempts to set it to non-zero values 772 in mallopt will fail. 773 */ 774 775 776 /* 777 USE_DL_PREFIX will prefix all public routines with the string 'dl'. 778 Useful to quickly avoid procedure declaration conflicts and linker 779 symbol conflicts with existing memory allocation routines. 780 781 */ 782 783 /* #define USE_DL_PREFIX */ 784 785 786 /* 787 788 Special defines for linux libc 789 790 Except when compiled using these special defines for Linux libc 791 using weak aliases, this malloc is NOT designed to work in 792 multithreaded applications. No semaphores or other concurrency 793 control are provided to ensure that multiple malloc or free calls 794 don't run at the same time, which could be disasterous. A single 795 semaphore could be used across malloc, realloc, and free (which is 796 essentially the effect of the linux weak alias approach). It would 797 be hard to obtain finer granularity. 798 799 */ 800 801 802 #ifdef INTERNAL_LINUX_C_LIB 803 804 #if __STD_C 805 806 Void_t * __default_morecore_init (ptrdiff_t); 807 Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init; 808 809 #else 810 811 Void_t * __default_morecore_init (); 812 Void_t *(*__morecore)() = __default_morecore_init; 813 814 #endif 815 816 #define MORECORE (*__morecore) 817 #define MORECORE_FAILURE 0 818 #define MORECORE_CLEARS 1 819 820 #else /* INTERNAL_LINUX_C_LIB */ 821 822 #if __STD_C 823 extern Void_t* sbrk(ptrdiff_t); 824 #else 825 extern Void_t* sbrk(); 826 #endif 827 828 #ifndef MORECORE 829 #define MORECORE sbrk 830 #endif 831 832 #ifndef MORECORE_FAILURE 833 #define MORECORE_FAILURE -1 834 #endif 835 836 #ifndef MORECORE_CLEARS 837 #define MORECORE_CLEARS 1 838 #endif 839 840 #endif /* INTERNAL_LINUX_C_LIB */ 841 842 #if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__) 843 844 #define cALLOc __libc_calloc 845 #define fREe __libc_free 846 #define mALLOc __libc_malloc 847 #define mEMALIGn __libc_memalign 848 #define rEALLOc __libc_realloc 849 #define vALLOc __libc_valloc 850 #define pvALLOc __libc_pvalloc 851 #define mALLINFo __libc_mallinfo 852 #define mALLOPt __libc_mallopt 853 854 #pragma weak calloc = __libc_calloc 855 #pragma weak free = __libc_free 856 #pragma weak cfree = __libc_free 857 #pragma weak malloc = __libc_malloc 858 #pragma weak memalign = __libc_memalign 859 #pragma weak realloc = __libc_realloc 860 #pragma weak valloc = __libc_valloc 861 #pragma weak pvalloc = __libc_pvalloc 862 #pragma weak mallinfo = __libc_mallinfo 863 #pragma weak mallopt = __libc_mallopt 864 865 #else 866 867 #ifdef USE_DL_PREFIX 868 #define cALLOc dlcalloc 869 #define fREe dlfree 870 #define mALLOc dlmalloc 871 #define mEMALIGn dlmemalign 872 #define rEALLOc dlrealloc 873 #define vALLOc dlvalloc 874 #define pvALLOc dlpvalloc 875 #define mALLINFo dlmallinfo 876 #define mALLOPt dlmallopt 877 #else /* USE_DL_PREFIX */ 878 #define cALLOc calloc 879 #define fREe free 880 #define mALLOc malloc 881 #define mEMALIGn memalign 882 #define rEALLOc realloc 883 #define vALLOc valloc 884 #define pvALLOc pvalloc 885 #define mALLINFo mallinfo 886 #define mALLOPt mallopt 887 #endif /* USE_DL_PREFIX */ 888 889 #endif 890 891 /* Public routines */ 892 893 #if __STD_C 894 895 Void_t* mALLOc(size_t); 896 void fREe(Void_t*); 897 Void_t* rEALLOc(Void_t*, size_t); 898 Void_t* mEMALIGn(size_t, size_t); 899 Void_t* vALLOc(size_t); 900 Void_t* pvALLOc(size_t); 901 Void_t* cALLOc(size_t, size_t); 902 void cfree(Void_t*); 903 int malloc_trim(size_t); 904 size_t malloc_usable_size(Void_t*); 905 void malloc_stats(); 906 int mALLOPt(int, int); 907 struct mallinfo mALLINFo(void); 908 #else 909 Void_t* mALLOc(); 910 void fREe(); 911 Void_t* rEALLOc(); 912 Void_t* mEMALIGn(); 913 Void_t* vALLOc(); 914 Void_t* pvALLOc(); 915 Void_t* cALLOc(); 916 void cfree(); 917 int malloc_trim(); 918 size_t malloc_usable_size(); 919 void malloc_stats(); 920 int mALLOPt(); 921 struct mallinfo mALLINFo(); 922 #endif 923 924 925 #ifdef __cplusplus 926 }; /* end of extern "C" */ 927 #endif 928 929 /* ---------- To make a malloc.h, end cutting here ------------ */ 930 #endif /* 0 */ /* Moved to malloc.h */ 931 932 #include <malloc.h> 933 #ifdef DEBUG 934 #if __STD_C 935 static void malloc_update_mallinfo (void); 936 void malloc_stats (void); 937 #else 938 static void malloc_update_mallinfo (); 939 void malloc_stats(); 940 #endif 941 #endif /* DEBUG */ 942 943 DECLARE_GLOBAL_DATA_PTR; 944 945 /* 946 Emulation of sbrk for WIN32 947 All code within the ifdef WIN32 is untested by me. 948 949 Thanks to Martin Fong and others for supplying this. 950 */ 951 952 953 #ifdef WIN32 954 955 #define AlignPage(add) (((add) + (malloc_getpagesize-1)) & \ 956 ~(malloc_getpagesize-1)) 957 #define AlignPage64K(add) (((add) + (0x10000 - 1)) & ~(0x10000 - 1)) 958 959 /* resrve 64MB to insure large contiguous space */ 960 #define RESERVED_SIZE (1024*1024*64) 961 #define NEXT_SIZE (2048*1024) 962 #define TOP_MEMORY ((unsigned long)2*1024*1024*1024) 963 964 struct GmListElement; 965 typedef struct GmListElement GmListElement; 966 967 struct GmListElement 968 { 969 GmListElement* next; 970 void* base; 971 }; 972 973 static GmListElement* head = 0; 974 static unsigned int gNextAddress = 0; 975 static unsigned int gAddressBase = 0; 976 static unsigned int gAllocatedSize = 0; 977 978 static 979 GmListElement* makeGmListElement (void* bas) 980 { 981 GmListElement* this; 982 this = (GmListElement*)(void*)LocalAlloc (0, sizeof (GmListElement)); 983 assert (this); 984 if (this) 985 { 986 this->base = bas; 987 this->next = head; 988 head = this; 989 } 990 return this; 991 } 992 993 void gcleanup () 994 { 995 BOOL rval; 996 assert ( (head == NULL) || (head->base == (void*)gAddressBase)); 997 if (gAddressBase && (gNextAddress - gAddressBase)) 998 { 999 rval = VirtualFree ((void*)gAddressBase, 1000 gNextAddress - gAddressBase, 1001 MEM_DECOMMIT); 1002 assert (rval); 1003 } 1004 while (head) 1005 { 1006 GmListElement* next = head->next; 1007 rval = VirtualFree (head->base, 0, MEM_RELEASE); 1008 assert (rval); 1009 LocalFree (head); 1010 head = next; 1011 } 1012 } 1013 1014 static 1015 void* findRegion (void* start_address, unsigned long size) 1016 { 1017 MEMORY_BASIC_INFORMATION info; 1018 if (size >= TOP_MEMORY) return NULL; 1019 1020 while ((unsigned long)start_address + size < TOP_MEMORY) 1021 { 1022 VirtualQuery (start_address, &info, sizeof (info)); 1023 if ((info.State == MEM_FREE) && (info.RegionSize >= size)) 1024 return start_address; 1025 else 1026 { 1027 /* Requested region is not available so see if the */ 1028 /* next region is available. Set 'start_address' */ 1029 /* to the next region and call 'VirtualQuery()' */ 1030 /* again. */ 1031 1032 start_address = (char*)info.BaseAddress + info.RegionSize; 1033 1034 /* Make sure we start looking for the next region */ 1035 /* on the *next* 64K boundary. Otherwise, even if */ 1036 /* the new region is free according to */ 1037 /* 'VirtualQuery()', the subsequent call to */ 1038 /* 'VirtualAlloc()' (which follows the call to */ 1039 /* this routine in 'wsbrk()') will round *down* */ 1040 /* the requested address to a 64K boundary which */ 1041 /* we already know is an address in the */ 1042 /* unavailable region. Thus, the subsequent call */ 1043 /* to 'VirtualAlloc()' will fail and bring us back */ 1044 /* here, causing us to go into an infinite loop. */ 1045 1046 start_address = 1047 (void *) AlignPage64K((unsigned long) start_address); 1048 } 1049 } 1050 return NULL; 1051 1052 } 1053 1054 1055 void* wsbrk (long size) 1056 { 1057 void* tmp; 1058 if (size > 0) 1059 { 1060 if (gAddressBase == 0) 1061 { 1062 gAllocatedSize = max (RESERVED_SIZE, AlignPage (size)); 1063 gNextAddress = gAddressBase = 1064 (unsigned int)VirtualAlloc (NULL, gAllocatedSize, 1065 MEM_RESERVE, PAGE_NOACCESS); 1066 } else if (AlignPage (gNextAddress + size) > (gAddressBase + 1067 gAllocatedSize)) 1068 { 1069 long new_size = max (NEXT_SIZE, AlignPage (size)); 1070 void* new_address = (void*)(gAddressBase+gAllocatedSize); 1071 do 1072 { 1073 new_address = findRegion (new_address, new_size); 1074 1075 if (new_address == 0) 1076 return (void*)-1; 1077 1078 gAddressBase = gNextAddress = 1079 (unsigned int)VirtualAlloc (new_address, new_size, 1080 MEM_RESERVE, PAGE_NOACCESS); 1081 /* repeat in case of race condition */ 1082 /* The region that we found has been snagged */ 1083 /* by another thread */ 1084 } 1085 while (gAddressBase == 0); 1086 1087 assert (new_address == (void*)gAddressBase); 1088 1089 gAllocatedSize = new_size; 1090 1091 if (!makeGmListElement ((void*)gAddressBase)) 1092 return (void*)-1; 1093 } 1094 if ((size + gNextAddress) > AlignPage (gNextAddress)) 1095 { 1096 void* res; 1097 res = VirtualAlloc ((void*)AlignPage (gNextAddress), 1098 (size + gNextAddress - 1099 AlignPage (gNextAddress)), 1100 MEM_COMMIT, PAGE_READWRITE); 1101 if (res == 0) 1102 return (void*)-1; 1103 } 1104 tmp = (void*)gNextAddress; 1105 gNextAddress = (unsigned int)tmp + size; 1106 return tmp; 1107 } 1108 else if (size < 0) 1109 { 1110 unsigned int alignedGoal = AlignPage (gNextAddress + size); 1111 /* Trim by releasing the virtual memory */ 1112 if (alignedGoal >= gAddressBase) 1113 { 1114 VirtualFree ((void*)alignedGoal, gNextAddress - alignedGoal, 1115 MEM_DECOMMIT); 1116 gNextAddress = gNextAddress + size; 1117 return (void*)gNextAddress; 1118 } 1119 else 1120 { 1121 VirtualFree ((void*)gAddressBase, gNextAddress - gAddressBase, 1122 MEM_DECOMMIT); 1123 gNextAddress = gAddressBase; 1124 return (void*)-1; 1125 } 1126 } 1127 else 1128 { 1129 return (void*)gNextAddress; 1130 } 1131 } 1132 1133 #endif 1134 1135 1136 1137 /* 1138 Type declarations 1139 */ 1140 1141 1142 struct malloc_chunk 1143 { 1144 INTERNAL_SIZE_T prev_size; /* Size of previous chunk (if free). */ 1145 INTERNAL_SIZE_T size; /* Size in bytes, including overhead. */ 1146 struct malloc_chunk* fd; /* double links -- used only if free. */ 1147 struct malloc_chunk* bk; 1148 } __attribute__((__may_alias__)) ; 1149 1150 typedef struct malloc_chunk* mchunkptr; 1151 1152 /* 1153 1154 malloc_chunk details: 1155 1156 (The following includes lightly edited explanations by Colin Plumb.) 1157 1158 Chunks of memory are maintained using a `boundary tag' method as 1159 described in e.g., Knuth or Standish. (See the paper by Paul 1160 Wilson ftp://ftp.cs.utexas.edu/pub/garbage/allocsrv.ps for a 1161 survey of such techniques.) Sizes of free chunks are stored both 1162 in the front of each chunk and at the end. This makes 1163 consolidating fragmented chunks into bigger chunks very fast. The 1164 size fields also hold bits representing whether chunks are free or 1165 in use. 1166 1167 An allocated chunk looks like this: 1168 1169 1170 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1171 | Size of previous chunk, if allocated | | 1172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1173 | Size of chunk, in bytes |P| 1174 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1175 | User data starts here... . 1176 . . 1177 . (malloc_usable_space() bytes) . 1178 . | 1179 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1180 | Size of chunk | 1181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1182 1183 1184 Where "chunk" is the front of the chunk for the purpose of most of 1185 the malloc code, but "mem" is the pointer that is returned to the 1186 user. "Nextchunk" is the beginning of the next contiguous chunk. 1187 1188 Chunks always begin on even word boundries, so the mem portion 1189 (which is returned to the user) is also on an even word boundary, and 1190 thus double-word aligned. 1191 1192 Free chunks are stored in circular doubly-linked lists, and look like this: 1193 1194 chunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1195 | Size of previous chunk | 1196 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1197 `head:' | Size of chunk, in bytes |P| 1198 mem-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1199 | Forward pointer to next chunk in list | 1200 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1201 | Back pointer to previous chunk in list | 1202 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1203 | Unused space (may be 0 bytes long) . 1204 . . 1205 . | 1206 nextchunk-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1207 `foot:' | Size of chunk, in bytes | 1208 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1209 1210 The P (PREV_INUSE) bit, stored in the unused low-order bit of the 1211 chunk size (which is always a multiple of two words), is an in-use 1212 bit for the *previous* chunk. If that bit is *clear*, then the 1213 word before the current chunk size contains the previous chunk 1214 size, and can be used to find the front of the previous chunk. 1215 (The very first chunk allocated always has this bit set, 1216 preventing access to non-existent (or non-owned) memory.) 1217 1218 Note that the `foot' of the current chunk is actually represented 1219 as the prev_size of the NEXT chunk. (This makes it easier to 1220 deal with alignments etc). 1221 1222 The two exceptions to all this are 1223 1224 1. The special chunk `top', which doesn't bother using the 1225 trailing size field since there is no 1226 next contiguous chunk that would have to index off it. (After 1227 initialization, `top' is forced to always exist. If it would 1228 become less than MINSIZE bytes long, it is replenished via 1229 malloc_extend_top.) 1230 1231 2. Chunks allocated via mmap, which have the second-lowest-order 1232 bit (IS_MMAPPED) set in their size fields. Because they are 1233 never merged or traversed from any other chunk, they have no 1234 foot size or inuse information. 1235 1236 Available chunks are kept in any of several places (all declared below): 1237 1238 * `av': An array of chunks serving as bin headers for consolidated 1239 chunks. Each bin is doubly linked. The bins are approximately 1240 proportionally (log) spaced. There are a lot of these bins 1241 (128). This may look excessive, but works very well in 1242 practice. All procedures maintain the invariant that no 1243 consolidated chunk physically borders another one. Chunks in 1244 bins are kept in size order, with ties going to the 1245 approximately least recently used chunk. 1246 1247 The chunks in each bin are maintained in decreasing sorted order by 1248 size. This is irrelevant for the small bins, which all contain 1249 the same-sized chunks, but facilitates best-fit allocation for 1250 larger chunks. (These lists are just sequential. Keeping them in 1251 order almost never requires enough traversal to warrant using 1252 fancier ordered data structures.) Chunks of the same size are 1253 linked with the most recently freed at the front, and allocations 1254 are taken from the back. This results in LRU or FIFO allocation 1255 order, which tends to give each chunk an equal opportunity to be 1256 consolidated with adjacent freed chunks, resulting in larger free 1257 chunks and less fragmentation. 1258 1259 * `top': The top-most available chunk (i.e., the one bordering the 1260 end of available memory) is treated specially. It is never 1261 included in any bin, is used only if no other chunk is 1262 available, and is released back to the system if it is very 1263 large (see M_TRIM_THRESHOLD). 1264 1265 * `last_remainder': A bin holding only the remainder of the 1266 most recently split (non-top) chunk. This bin is checked 1267 before other non-fitting chunks, so as to provide better 1268 locality for runs of sequentially allocated chunks. 1269 1270 * Implicitly, through the host system's memory mapping tables. 1271 If supported, requests greater than a threshold are usually 1272 serviced via calls to mmap, and then later released via munmap. 1273 1274 */ 1275 1276 /* sizes, alignments */ 1277 1278 #define SIZE_SZ (sizeof(INTERNAL_SIZE_T)) 1279 #define MALLOC_ALIGNMENT (SIZE_SZ + SIZE_SZ) 1280 #define MALLOC_ALIGN_MASK (MALLOC_ALIGNMENT - 1) 1281 #define MINSIZE (sizeof(struct malloc_chunk)) 1282 1283 /* conversion from malloc headers to user pointers, and back */ 1284 1285 #define chunk2mem(p) ((Void_t*)((char*)(p) + 2*SIZE_SZ)) 1286 #define mem2chunk(mem) ((mchunkptr)((char*)(mem) - 2*SIZE_SZ)) 1287 1288 /* pad request bytes into a usable size */ 1289 1290 #define request2size(req) \ 1291 (((long)((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) < \ 1292 (long)(MINSIZE + MALLOC_ALIGN_MASK)) ? MINSIZE : \ 1293 (((req) + (SIZE_SZ + MALLOC_ALIGN_MASK)) & ~(MALLOC_ALIGN_MASK))) 1294 1295 /* Check if m has acceptable alignment */ 1296 1297 #define aligned_OK(m) (((unsigned long)((m)) & (MALLOC_ALIGN_MASK)) == 0) 1298 1299 1300 1301 1302 /* 1303 Physical chunk operations 1304 */ 1305 1306 1307 /* size field is or'ed with PREV_INUSE when previous adjacent chunk in use */ 1308 1309 #define PREV_INUSE 0x1 1310 1311 /* size field is or'ed with IS_MMAPPED if the chunk was obtained with mmap() */ 1312 1313 #define IS_MMAPPED 0x2 1314 1315 /* Bits to mask off when extracting size */ 1316 1317 #define SIZE_BITS (PREV_INUSE|IS_MMAPPED) 1318 1319 1320 /* Ptr to next physical malloc_chunk. */ 1321 1322 #define next_chunk(p) ((mchunkptr)( ((char*)(p)) + ((p)->size & ~PREV_INUSE) )) 1323 1324 /* Ptr to previous physical malloc_chunk */ 1325 1326 #define prev_chunk(p)\ 1327 ((mchunkptr)( ((char*)(p)) - ((p)->prev_size) )) 1328 1329 1330 /* Treat space at ptr + offset as a chunk */ 1331 1332 #define chunk_at_offset(p, s) ((mchunkptr)(((char*)(p)) + (s))) 1333 1334 1335 1336 1337 /* 1338 Dealing with use bits 1339 */ 1340 1341 /* extract p's inuse bit */ 1342 1343 #define inuse(p)\ 1344 ((((mchunkptr)(((char*)(p))+((p)->size & ~PREV_INUSE)))->size) & PREV_INUSE) 1345 1346 /* extract inuse bit of previous chunk */ 1347 1348 #define prev_inuse(p) ((p)->size & PREV_INUSE) 1349 1350 /* check for mmap()'ed chunk */ 1351 1352 #define chunk_is_mmapped(p) ((p)->size & IS_MMAPPED) 1353 1354 /* set/clear chunk as in use without otherwise disturbing */ 1355 1356 #define set_inuse(p)\ 1357 ((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size |= PREV_INUSE 1358 1359 #define clear_inuse(p)\ 1360 ((mchunkptr)(((char*)(p)) + ((p)->size & ~PREV_INUSE)))->size &= ~(PREV_INUSE) 1361 1362 /* check/set/clear inuse bits in known places */ 1363 1364 #define inuse_bit_at_offset(p, s)\ 1365 (((mchunkptr)(((char*)(p)) + (s)))->size & PREV_INUSE) 1366 1367 #define set_inuse_bit_at_offset(p, s)\ 1368 (((mchunkptr)(((char*)(p)) + (s)))->size |= PREV_INUSE) 1369 1370 #define clear_inuse_bit_at_offset(p, s)\ 1371 (((mchunkptr)(((char*)(p)) + (s)))->size &= ~(PREV_INUSE)) 1372 1373 1374 1375 1376 /* 1377 Dealing with size fields 1378 */ 1379 1380 /* Get size, ignoring use bits */ 1381 1382 #define chunksize(p) ((p)->size & ~(SIZE_BITS)) 1383 1384 /* Set size at head, without disturbing its use bit */ 1385 1386 #define set_head_size(p, s) ((p)->size = (((p)->size & PREV_INUSE) | (s))) 1387 1388 /* Set size/use ignoring previous bits in header */ 1389 1390 #define set_head(p, s) ((p)->size = (s)) 1391 1392 /* Set size at footer (only when chunk is not in use) */ 1393 1394 #define set_foot(p, s) (((mchunkptr)((char*)(p) + (s)))->prev_size = (s)) 1395 1396 1397 1398 1399 1400 /* 1401 Bins 1402 1403 The bins, `av_' are an array of pairs of pointers serving as the 1404 heads of (initially empty) doubly-linked lists of chunks, laid out 1405 in a way so that each pair can be treated as if it were in a 1406 malloc_chunk. (This way, the fd/bk offsets for linking bin heads 1407 and chunks are the same). 1408 1409 Bins for sizes < 512 bytes contain chunks of all the same size, spaced 1410 8 bytes apart. Larger bins are approximately logarithmically 1411 spaced. (See the table below.) The `av_' array is never mentioned 1412 directly in the code, but instead via bin access macros. 1413 1414 Bin layout: 1415 1416 64 bins of size 8 1417 32 bins of size 64 1418 16 bins of size 512 1419 8 bins of size 4096 1420 4 bins of size 32768 1421 2 bins of size 262144 1422 1 bin of size what's left 1423 1424 There is actually a little bit of slop in the numbers in bin_index 1425 for the sake of speed. This makes no difference elsewhere. 1426 1427 The special chunks `top' and `last_remainder' get their own bins, 1428 (this is implemented via yet more trickery with the av_ array), 1429 although `top' is never properly linked to its bin since it is 1430 always handled specially. 1431 1432 */ 1433 1434 #define NAV 128 /* number of bins */ 1435 1436 typedef struct malloc_chunk* mbinptr; 1437 1438 /* access macros */ 1439 1440 #define bin_at(i) ((mbinptr)((char*)&(av_[2*(i) + 2]) - 2*SIZE_SZ)) 1441 #define next_bin(b) ((mbinptr)((char*)(b) + 2 * sizeof(mbinptr))) 1442 #define prev_bin(b) ((mbinptr)((char*)(b) - 2 * sizeof(mbinptr))) 1443 1444 /* 1445 The first 2 bins are never indexed. The corresponding av_ cells are instead 1446 used for bookkeeping. This is not to save space, but to simplify 1447 indexing, maintain locality, and avoid some initialization tests. 1448 */ 1449 1450 #define top (av_[2]) /* The topmost chunk */ 1451 #define last_remainder (bin_at(1)) /* remainder from last split */ 1452 1453 1454 /* 1455 Because top initially points to its own bin with initial 1456 zero size, thus forcing extension on the first malloc request, 1457 we avoid having any special code in malloc to check whether 1458 it even exists yet. But we still need to in malloc_extend_top. 1459 */ 1460 1461 #define initial_top ((mchunkptr)(bin_at(0))) 1462 1463 /* Helper macro to initialize bins */ 1464 1465 #define IAV(i) bin_at(i), bin_at(i) 1466 1467 static mbinptr av_[NAV * 2 + 2] = { 1468 NULL, NULL, 1469 IAV(0), IAV(1), IAV(2), IAV(3), IAV(4), IAV(5), IAV(6), IAV(7), 1470 IAV(8), IAV(9), IAV(10), IAV(11), IAV(12), IAV(13), IAV(14), IAV(15), 1471 IAV(16), IAV(17), IAV(18), IAV(19), IAV(20), IAV(21), IAV(22), IAV(23), 1472 IAV(24), IAV(25), IAV(26), IAV(27), IAV(28), IAV(29), IAV(30), IAV(31), 1473 IAV(32), IAV(33), IAV(34), IAV(35), IAV(36), IAV(37), IAV(38), IAV(39), 1474 IAV(40), IAV(41), IAV(42), IAV(43), IAV(44), IAV(45), IAV(46), IAV(47), 1475 IAV(48), IAV(49), IAV(50), IAV(51), IAV(52), IAV(53), IAV(54), IAV(55), 1476 IAV(56), IAV(57), IAV(58), IAV(59), IAV(60), IAV(61), IAV(62), IAV(63), 1477 IAV(64), IAV(65), IAV(66), IAV(67), IAV(68), IAV(69), IAV(70), IAV(71), 1478 IAV(72), IAV(73), IAV(74), IAV(75), IAV(76), IAV(77), IAV(78), IAV(79), 1479 IAV(80), IAV(81), IAV(82), IAV(83), IAV(84), IAV(85), IAV(86), IAV(87), 1480 IAV(88), IAV(89), IAV(90), IAV(91), IAV(92), IAV(93), IAV(94), IAV(95), 1481 IAV(96), IAV(97), IAV(98), IAV(99), IAV(100), IAV(101), IAV(102), IAV(103), 1482 IAV(104), IAV(105), IAV(106), IAV(107), IAV(108), IAV(109), IAV(110), IAV(111), 1483 IAV(112), IAV(113), IAV(114), IAV(115), IAV(116), IAV(117), IAV(118), IAV(119), 1484 IAV(120), IAV(121), IAV(122), IAV(123), IAV(124), IAV(125), IAV(126), IAV(127) 1485 }; 1486 1487 #ifdef CONFIG_NEEDS_MANUAL_RELOC 1488 static void malloc_bin_reloc(void) 1489 { 1490 mbinptr *p = &av_[2]; 1491 size_t i; 1492 1493 for (i = 2; i < ARRAY_SIZE(av_); ++i, ++p) 1494 *p = (mbinptr)((ulong)*p + gd->reloc_off); 1495 } 1496 #else 1497 static inline void malloc_bin_reloc(void) {} 1498 #endif 1499 1500 ulong mem_malloc_start = 0; 1501 ulong mem_malloc_end = 0; 1502 ulong mem_malloc_brk = 0; 1503 1504 void *sbrk(ptrdiff_t increment) 1505 { 1506 ulong old = mem_malloc_brk; 1507 ulong new = old + increment; 1508 1509 /* 1510 * if we are giving memory back make sure we clear it out since 1511 * we set MORECORE_CLEARS to 1 1512 */ 1513 if (increment < 0) 1514 memset((void *)new, 0, -increment); 1515 1516 if ((new < mem_malloc_start) || (new > mem_malloc_end)) 1517 return (void *)MORECORE_FAILURE; 1518 1519 mem_malloc_brk = new; 1520 1521 return (void *)old; 1522 } 1523 1524 void mem_malloc_init(ulong start, ulong size) 1525 { 1526 mem_malloc_start = start; 1527 mem_malloc_end = start + size; 1528 mem_malloc_brk = start; 1529 1530 memset((void *)mem_malloc_start, 0, size); 1531 1532 malloc_bin_reloc(); 1533 } 1534 1535 /* field-extraction macros */ 1536 1537 #define first(b) ((b)->fd) 1538 #define last(b) ((b)->bk) 1539 1540 /* 1541 Indexing into bins 1542 */ 1543 1544 #define bin_index(sz) \ 1545 (((((unsigned long)(sz)) >> 9) == 0) ? (((unsigned long)(sz)) >> 3): \ 1546 ((((unsigned long)(sz)) >> 9) <= 4) ? 56 + (((unsigned long)(sz)) >> 6): \ 1547 ((((unsigned long)(sz)) >> 9) <= 20) ? 91 + (((unsigned long)(sz)) >> 9): \ 1548 ((((unsigned long)(sz)) >> 9) <= 84) ? 110 + (((unsigned long)(sz)) >> 12): \ 1549 ((((unsigned long)(sz)) >> 9) <= 340) ? 119 + (((unsigned long)(sz)) >> 15): \ 1550 ((((unsigned long)(sz)) >> 9) <= 1364) ? 124 + (((unsigned long)(sz)) >> 18): \ 1551 126) 1552 /* 1553 bins for chunks < 512 are all spaced 8 bytes apart, and hold 1554 identically sized chunks. This is exploited in malloc. 1555 */ 1556 1557 #define MAX_SMALLBIN 63 1558 #define MAX_SMALLBIN_SIZE 512 1559 #define SMALLBIN_WIDTH 8 1560 1561 #define smallbin_index(sz) (((unsigned long)(sz)) >> 3) 1562 1563 /* 1564 Requests are `small' if both the corresponding and the next bin are small 1565 */ 1566 1567 #define is_small_request(nb) (nb < MAX_SMALLBIN_SIZE - SMALLBIN_WIDTH) 1568 1569 1570 1571 /* 1572 To help compensate for the large number of bins, a one-level index 1573 structure is used for bin-by-bin searching. `binblocks' is a 1574 one-word bitvector recording whether groups of BINBLOCKWIDTH bins 1575 have any (possibly) non-empty bins, so they can be skipped over 1576 all at once during during traversals. The bits are NOT always 1577 cleared as soon as all bins in a block are empty, but instead only 1578 when all are noticed to be empty during traversal in malloc. 1579 */ 1580 1581 #define BINBLOCKWIDTH 4 /* bins per block */ 1582 1583 #define binblocks_r ((INTERNAL_SIZE_T)av_[1]) /* bitvector of nonempty blocks */ 1584 #define binblocks_w (av_[1]) 1585 1586 /* bin<->block macros */ 1587 1588 #define idx2binblock(ix) ((unsigned)1 << (ix / BINBLOCKWIDTH)) 1589 #define mark_binblock(ii) (binblocks_w = (mbinptr)(binblocks_r | idx2binblock(ii))) 1590 #define clear_binblock(ii) (binblocks_w = (mbinptr)(binblocks_r & ~(idx2binblock(ii)))) 1591 1592 1593 1594 1595 1596 /* Other static bookkeeping data */ 1597 1598 /* variables holding tunable values */ 1599 1600 static unsigned long trim_threshold = DEFAULT_TRIM_THRESHOLD; 1601 static unsigned long top_pad = DEFAULT_TOP_PAD; 1602 static unsigned int n_mmaps_max = DEFAULT_MMAP_MAX; 1603 static unsigned long mmap_threshold = DEFAULT_MMAP_THRESHOLD; 1604 1605 /* The first value returned from sbrk */ 1606 static char* sbrk_base = (char*)(-1); 1607 1608 /* The maximum memory obtained from system via sbrk */ 1609 static unsigned long max_sbrked_mem = 0; 1610 1611 /* The maximum via either sbrk or mmap */ 1612 static unsigned long max_total_mem = 0; 1613 1614 /* internal working copy of mallinfo */ 1615 static struct mallinfo current_mallinfo = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; 1616 1617 /* The total memory obtained from system via sbrk */ 1618 #define sbrked_mem (current_mallinfo.arena) 1619 1620 /* Tracking mmaps */ 1621 1622 #ifdef DEBUG 1623 static unsigned int n_mmaps = 0; 1624 #endif /* DEBUG */ 1625 static unsigned long mmapped_mem = 0; 1626 #if HAVE_MMAP 1627 static unsigned int max_n_mmaps = 0; 1628 static unsigned long max_mmapped_mem = 0; 1629 #endif 1630 1631 1632 1633 /* 1634 Debugging support 1635 */ 1636 1637 #ifdef DEBUG 1638 1639 1640 /* 1641 These routines make a number of assertions about the states 1642 of data structures that should be true at all times. If any 1643 are not true, it's very likely that a user program has somehow 1644 trashed memory. (It's also possible that there is a coding error 1645 in malloc. In which case, please report it!) 1646 */ 1647 1648 #if __STD_C 1649 static void do_check_chunk(mchunkptr p) 1650 #else 1651 static void do_check_chunk(p) mchunkptr p; 1652 #endif 1653 { 1654 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE; 1655 1656 /* No checkable chunk is mmapped */ 1657 assert(!chunk_is_mmapped(p)); 1658 1659 /* Check for legal address ... */ 1660 assert((char*)p >= sbrk_base); 1661 if (p != top) 1662 assert((char*)p + sz <= (char*)top); 1663 else 1664 assert((char*)p + sz <= sbrk_base + sbrked_mem); 1665 1666 } 1667 1668 1669 #if __STD_C 1670 static void do_check_free_chunk(mchunkptr p) 1671 #else 1672 static void do_check_free_chunk(p) mchunkptr p; 1673 #endif 1674 { 1675 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE; 1676 mchunkptr next = chunk_at_offset(p, sz); 1677 1678 do_check_chunk(p); 1679 1680 /* Check whether it claims to be free ... */ 1681 assert(!inuse(p)); 1682 1683 /* Unless a special marker, must have OK fields */ 1684 if ((long)sz >= (long)MINSIZE) 1685 { 1686 assert((sz & MALLOC_ALIGN_MASK) == 0); 1687 assert(aligned_OK(chunk2mem(p))); 1688 /* ... matching footer field */ 1689 assert(next->prev_size == sz); 1690 /* ... and is fully consolidated */ 1691 assert(prev_inuse(p)); 1692 assert (next == top || inuse(next)); 1693 1694 /* ... and has minimally sane links */ 1695 assert(p->fd->bk == p); 1696 assert(p->bk->fd == p); 1697 } 1698 else /* markers are always of size SIZE_SZ */ 1699 assert(sz == SIZE_SZ); 1700 } 1701 1702 #if __STD_C 1703 static void do_check_inuse_chunk(mchunkptr p) 1704 #else 1705 static void do_check_inuse_chunk(p) mchunkptr p; 1706 #endif 1707 { 1708 mchunkptr next = next_chunk(p); 1709 do_check_chunk(p); 1710 1711 /* Check whether it claims to be in use ... */ 1712 assert(inuse(p)); 1713 1714 /* ... and is surrounded by OK chunks. 1715 Since more things can be checked with free chunks than inuse ones, 1716 if an inuse chunk borders them and debug is on, it's worth doing them. 1717 */ 1718 if (!prev_inuse(p)) 1719 { 1720 mchunkptr prv = prev_chunk(p); 1721 assert(next_chunk(prv) == p); 1722 do_check_free_chunk(prv); 1723 } 1724 if (next == top) 1725 { 1726 assert(prev_inuse(next)); 1727 assert(chunksize(next) >= MINSIZE); 1728 } 1729 else if (!inuse(next)) 1730 do_check_free_chunk(next); 1731 1732 } 1733 1734 #if __STD_C 1735 static void do_check_malloced_chunk(mchunkptr p, INTERNAL_SIZE_T s) 1736 #else 1737 static void do_check_malloced_chunk(p, s) mchunkptr p; INTERNAL_SIZE_T s; 1738 #endif 1739 { 1740 INTERNAL_SIZE_T sz = p->size & ~PREV_INUSE; 1741 long room = sz - s; 1742 1743 do_check_inuse_chunk(p); 1744 1745 /* Legal size ... */ 1746 assert((long)sz >= (long)MINSIZE); 1747 assert((sz & MALLOC_ALIGN_MASK) == 0); 1748 assert(room >= 0); 1749 assert(room < (long)MINSIZE); 1750 1751 /* ... and alignment */ 1752 assert(aligned_OK(chunk2mem(p))); 1753 1754 1755 /* ... and was allocated at front of an available chunk */ 1756 assert(prev_inuse(p)); 1757 1758 } 1759 1760 1761 #define check_free_chunk(P) do_check_free_chunk(P) 1762 #define check_inuse_chunk(P) do_check_inuse_chunk(P) 1763 #define check_chunk(P) do_check_chunk(P) 1764 #define check_malloced_chunk(P,N) do_check_malloced_chunk(P,N) 1765 #else 1766 #define check_free_chunk(P) 1767 #define check_inuse_chunk(P) 1768 #define check_chunk(P) 1769 #define check_malloced_chunk(P,N) 1770 #endif 1771 1772 1773 1774 /* 1775 Macro-based internal utilities 1776 */ 1777 1778 1779 /* 1780 Linking chunks in bin lists. 1781 Call these only with variables, not arbitrary expressions, as arguments. 1782 */ 1783 1784 /* 1785 Place chunk p of size s in its bin, in size order, 1786 putting it ahead of others of same size. 1787 */ 1788 1789 1790 #define frontlink(P, S, IDX, BK, FD) \ 1791 { \ 1792 if (S < MAX_SMALLBIN_SIZE) \ 1793 { \ 1794 IDX = smallbin_index(S); \ 1795 mark_binblock(IDX); \ 1796 BK = bin_at(IDX); \ 1797 FD = BK->fd; \ 1798 P->bk = BK; \ 1799 P->fd = FD; \ 1800 FD->bk = BK->fd = P; \ 1801 } \ 1802 else \ 1803 { \ 1804 IDX = bin_index(S); \ 1805 BK = bin_at(IDX); \ 1806 FD = BK->fd; \ 1807 if (FD == BK) mark_binblock(IDX); \ 1808 else \ 1809 { \ 1810 while (FD != BK && S < chunksize(FD)) FD = FD->fd; \ 1811 BK = FD->bk; \ 1812 } \ 1813 P->bk = BK; \ 1814 P->fd = FD; \ 1815 FD->bk = BK->fd = P; \ 1816 } \ 1817 } 1818 1819 1820 /* take a chunk off a list */ 1821 1822 #define unlink(P, BK, FD) \ 1823 { \ 1824 BK = P->bk; \ 1825 FD = P->fd; \ 1826 FD->bk = BK; \ 1827 BK->fd = FD; \ 1828 } \ 1829 1830 /* Place p as the last remainder */ 1831 1832 #define link_last_remainder(P) \ 1833 { \ 1834 last_remainder->fd = last_remainder->bk = P; \ 1835 P->fd = P->bk = last_remainder; \ 1836 } 1837 1838 /* Clear the last_remainder bin */ 1839 1840 #define clear_last_remainder \ 1841 (last_remainder->fd = last_remainder->bk = last_remainder) 1842 1843 1844 1845 1846 1847 /* Routines dealing with mmap(). */ 1848 1849 #if HAVE_MMAP 1850 1851 #if __STD_C 1852 static mchunkptr mmap_chunk(size_t size) 1853 #else 1854 static mchunkptr mmap_chunk(size) size_t size; 1855 #endif 1856 { 1857 size_t page_mask = malloc_getpagesize - 1; 1858 mchunkptr p; 1859 1860 #ifndef MAP_ANONYMOUS 1861 static int fd = -1; 1862 #endif 1863 1864 if(n_mmaps >= n_mmaps_max) return 0; /* too many regions */ 1865 1866 /* For mmapped chunks, the overhead is one SIZE_SZ unit larger, because 1867 * there is no following chunk whose prev_size field could be used. 1868 */ 1869 size = (size + SIZE_SZ + page_mask) & ~page_mask; 1870 1871 #ifdef MAP_ANONYMOUS 1872 p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, 1873 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); 1874 #else /* !MAP_ANONYMOUS */ 1875 if (fd < 0) 1876 { 1877 fd = open("/dev/zero", O_RDWR); 1878 if(fd < 0) return 0; 1879 } 1880 p = (mchunkptr)mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); 1881 #endif 1882 1883 if(p == (mchunkptr)-1) return 0; 1884 1885 n_mmaps++; 1886 if (n_mmaps > max_n_mmaps) max_n_mmaps = n_mmaps; 1887 1888 /* We demand that eight bytes into a page must be 8-byte aligned. */ 1889 assert(aligned_OK(chunk2mem(p))); 1890 1891 /* The offset to the start of the mmapped region is stored 1892 * in the prev_size field of the chunk; normally it is zero, 1893 * but that can be changed in memalign(). 1894 */ 1895 p->prev_size = 0; 1896 set_head(p, size|IS_MMAPPED); 1897 1898 mmapped_mem += size; 1899 if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem) 1900 max_mmapped_mem = mmapped_mem; 1901 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) 1902 max_total_mem = mmapped_mem + sbrked_mem; 1903 return p; 1904 } 1905 1906 #if __STD_C 1907 static void munmap_chunk(mchunkptr p) 1908 #else 1909 static void munmap_chunk(p) mchunkptr p; 1910 #endif 1911 { 1912 INTERNAL_SIZE_T size = chunksize(p); 1913 int ret; 1914 1915 assert (chunk_is_mmapped(p)); 1916 assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem)); 1917 assert((n_mmaps > 0)); 1918 assert(((p->prev_size + size) & (malloc_getpagesize-1)) == 0); 1919 1920 n_mmaps--; 1921 mmapped_mem -= (size + p->prev_size); 1922 1923 ret = munmap((char *)p - p->prev_size, size + p->prev_size); 1924 1925 /* munmap returns non-zero on failure */ 1926 assert(ret == 0); 1927 } 1928 1929 #if HAVE_MREMAP 1930 1931 #if __STD_C 1932 static mchunkptr mremap_chunk(mchunkptr p, size_t new_size) 1933 #else 1934 static mchunkptr mremap_chunk(p, new_size) mchunkptr p; size_t new_size; 1935 #endif 1936 { 1937 size_t page_mask = malloc_getpagesize - 1; 1938 INTERNAL_SIZE_T offset = p->prev_size; 1939 INTERNAL_SIZE_T size = chunksize(p); 1940 char *cp; 1941 1942 assert (chunk_is_mmapped(p)); 1943 assert(! ((char*)p >= sbrk_base && (char*)p < sbrk_base + sbrked_mem)); 1944 assert((n_mmaps > 0)); 1945 assert(((size + offset) & (malloc_getpagesize-1)) == 0); 1946 1947 /* Note the extra SIZE_SZ overhead as in mmap_chunk(). */ 1948 new_size = (new_size + offset + SIZE_SZ + page_mask) & ~page_mask; 1949 1950 cp = (char *)mremap((char *)p - offset, size + offset, new_size, 1); 1951 1952 if (cp == (char *)-1) return 0; 1953 1954 p = (mchunkptr)(cp + offset); 1955 1956 assert(aligned_OK(chunk2mem(p))); 1957 1958 assert((p->prev_size == offset)); 1959 set_head(p, (new_size - offset)|IS_MMAPPED); 1960 1961 mmapped_mem -= size + offset; 1962 mmapped_mem += new_size; 1963 if ((unsigned long)mmapped_mem > (unsigned long)max_mmapped_mem) 1964 max_mmapped_mem = mmapped_mem; 1965 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) 1966 max_total_mem = mmapped_mem + sbrked_mem; 1967 return p; 1968 } 1969 1970 #endif /* HAVE_MREMAP */ 1971 1972 #endif /* HAVE_MMAP */ 1973 1974 1975 1976 1977 /* 1978 Extend the top-most chunk by obtaining memory from system. 1979 Main interface to sbrk (but see also malloc_trim). 1980 */ 1981 1982 #if __STD_C 1983 static void malloc_extend_top(INTERNAL_SIZE_T nb) 1984 #else 1985 static void malloc_extend_top(nb) INTERNAL_SIZE_T nb; 1986 #endif 1987 { 1988 char* brk; /* return value from sbrk */ 1989 INTERNAL_SIZE_T front_misalign; /* unusable bytes at front of sbrked space */ 1990 INTERNAL_SIZE_T correction; /* bytes for 2nd sbrk call */ 1991 char* new_brk; /* return of 2nd sbrk call */ 1992 INTERNAL_SIZE_T top_size; /* new size of top chunk */ 1993 1994 mchunkptr old_top = top; /* Record state of old top */ 1995 INTERNAL_SIZE_T old_top_size = chunksize(old_top); 1996 char* old_end = (char*)(chunk_at_offset(old_top, old_top_size)); 1997 1998 /* Pad request with top_pad plus minimal overhead */ 1999 2000 INTERNAL_SIZE_T sbrk_size = nb + top_pad + MINSIZE; 2001 unsigned long pagesz = malloc_getpagesize; 2002 2003 /* If not the first time through, round to preserve page boundary */ 2004 /* Otherwise, we need to correct to a page size below anyway. */ 2005 /* (We also correct below if an intervening foreign sbrk call.) */ 2006 2007 if (sbrk_base != (char*)(-1)) 2008 sbrk_size = (sbrk_size + (pagesz - 1)) & ~(pagesz - 1); 2009 2010 brk = (char*)(MORECORE (sbrk_size)); 2011 2012 /* Fail if sbrk failed or if a foreign sbrk call killed our space */ 2013 if (brk == (char*)(MORECORE_FAILURE) || 2014 (brk < old_end && old_top != initial_top)) 2015 return; 2016 2017 sbrked_mem += sbrk_size; 2018 2019 if (brk == old_end) /* can just add bytes to current top */ 2020 { 2021 top_size = sbrk_size + old_top_size; 2022 set_head(top, top_size | PREV_INUSE); 2023 } 2024 else 2025 { 2026 if (sbrk_base == (char*)(-1)) /* First time through. Record base */ 2027 sbrk_base = brk; 2028 else /* Someone else called sbrk(). Count those bytes as sbrked_mem. */ 2029 sbrked_mem += brk - (char*)old_end; 2030 2031 /* Guarantee alignment of first new chunk made from this space */ 2032 front_misalign = (unsigned long)chunk2mem(brk) & MALLOC_ALIGN_MASK; 2033 if (front_misalign > 0) 2034 { 2035 correction = (MALLOC_ALIGNMENT) - front_misalign; 2036 brk += correction; 2037 } 2038 else 2039 correction = 0; 2040 2041 /* Guarantee the next brk will be at a page boundary */ 2042 2043 correction += ((((unsigned long)(brk + sbrk_size))+(pagesz-1)) & 2044 ~(pagesz - 1)) - ((unsigned long)(brk + sbrk_size)); 2045 2046 /* Allocate correction */ 2047 new_brk = (char*)(MORECORE (correction)); 2048 if (new_brk == (char*)(MORECORE_FAILURE)) return; 2049 2050 sbrked_mem += correction; 2051 2052 top = (mchunkptr)brk; 2053 top_size = new_brk - brk + correction; 2054 set_head(top, top_size | PREV_INUSE); 2055 2056 if (old_top != initial_top) 2057 { 2058 2059 /* There must have been an intervening foreign sbrk call. */ 2060 /* A double fencepost is necessary to prevent consolidation */ 2061 2062 /* If not enough space to do this, then user did something very wrong */ 2063 if (old_top_size < MINSIZE) 2064 { 2065 set_head(top, PREV_INUSE); /* will force null return from malloc */ 2066 return; 2067 } 2068 2069 /* Also keep size a multiple of MALLOC_ALIGNMENT */ 2070 old_top_size = (old_top_size - 3*SIZE_SZ) & ~MALLOC_ALIGN_MASK; 2071 set_head_size(old_top, old_top_size); 2072 chunk_at_offset(old_top, old_top_size )->size = 2073 SIZE_SZ|PREV_INUSE; 2074 chunk_at_offset(old_top, old_top_size + SIZE_SZ)->size = 2075 SIZE_SZ|PREV_INUSE; 2076 /* If possible, release the rest. */ 2077 if (old_top_size >= MINSIZE) 2078 fREe(chunk2mem(old_top)); 2079 } 2080 } 2081 2082 if ((unsigned long)sbrked_mem > (unsigned long)max_sbrked_mem) 2083 max_sbrked_mem = sbrked_mem; 2084 if ((unsigned long)(mmapped_mem + sbrked_mem) > (unsigned long)max_total_mem) 2085 max_total_mem = mmapped_mem + sbrked_mem; 2086 2087 /* We always land on a page boundary */ 2088 assert(((unsigned long)((char*)top + top_size) & (pagesz - 1)) == 0); 2089 } 2090 2091 2092 2093 2094 /* Main public routines */ 2095 2096 2097 /* 2098 Malloc Algorthim: 2099 2100 The requested size is first converted into a usable form, `nb'. 2101 This currently means to add 4 bytes overhead plus possibly more to 2102 obtain 8-byte alignment and/or to obtain a size of at least 2103 MINSIZE (currently 16 bytes), the smallest allocatable size. 2104 (All fits are considered `exact' if they are within MINSIZE bytes.) 2105 2106 From there, the first successful of the following steps is taken: 2107 2108 1. The bin corresponding to the request size is scanned, and if 2109 a chunk of exactly the right size is found, it is taken. 2110 2111 2. The most recently remaindered chunk is used if it is big 2112 enough. This is a form of (roving) first fit, used only in 2113 the absence of exact fits. Runs of consecutive requests use 2114 the remainder of the chunk used for the previous such request 2115 whenever possible. This limited use of a first-fit style 2116 allocation strategy tends to give contiguous chunks 2117 coextensive lifetimes, which improves locality and can reduce 2118 fragmentation in the long run. 2119 2120 3. Other bins are scanned in increasing size order, using a 2121 chunk big enough to fulfill the request, and splitting off 2122 any remainder. This search is strictly by best-fit; i.e., 2123 the smallest (with ties going to approximately the least 2124 recently used) chunk that fits is selected. 2125 2126 4. If large enough, the chunk bordering the end of memory 2127 (`top') is split off. (This use of `top' is in accord with 2128 the best-fit search rule. In effect, `top' is treated as 2129 larger (and thus less well fitting) than any other available 2130 chunk since it can be extended to be as large as necessary 2131 (up to system limitations). 2132 2133 5. If the request size meets the mmap threshold and the 2134 system supports mmap, and there are few enough currently 2135 allocated mmapped regions, and a call to mmap succeeds, 2136 the request is allocated via direct memory mapping. 2137 2138 6. Otherwise, the top of memory is extended by 2139 obtaining more space from the system (normally using sbrk, 2140 but definable to anything else via the MORECORE macro). 2141 Memory is gathered from the system (in system page-sized 2142 units) in a way that allows chunks obtained across different 2143 sbrk calls to be consolidated, but does not require 2144 contiguous memory. Thus, it should be safe to intersperse 2145 mallocs with other sbrk calls. 2146 2147 2148 All allocations are made from the the `lowest' part of any found 2149 chunk. (The implementation invariant is that prev_inuse is 2150 always true of any allocated chunk; i.e., that each allocated 2151 chunk borders either a previously allocated and still in-use chunk, 2152 or the base of its memory arena.) 2153 2154 */ 2155 2156 #if __STD_C 2157 Void_t* mALLOc(size_t bytes) 2158 #else 2159 Void_t* mALLOc(bytes) size_t bytes; 2160 #endif 2161 { 2162 mchunkptr victim; /* inspected/selected chunk */ 2163 INTERNAL_SIZE_T victim_size; /* its size */ 2164 int idx; /* index for bin traversal */ 2165 mbinptr bin; /* associated bin */ 2166 mchunkptr remainder; /* remainder from a split */ 2167 long remainder_size; /* its size */ 2168 int remainder_index; /* its bin index */ 2169 unsigned long block; /* block traverser bit */ 2170 int startidx; /* first bin of a traversed block */ 2171 mchunkptr fwd; /* misc temp for linking */ 2172 mchunkptr bck; /* misc temp for linking */ 2173 mbinptr q; /* misc temp */ 2174 2175 INTERNAL_SIZE_T nb; 2176 2177 /* check if mem_malloc_init() was run */ 2178 if ((mem_malloc_start == 0) && (mem_malloc_end == 0)) { 2179 /* not initialized yet */ 2180 return NULL; 2181 } 2182 2183 if ((long)bytes < 0) return NULL; 2184 2185 nb = request2size(bytes); /* padded request size; */ 2186 2187 /* Check for exact match in a bin */ 2188 2189 if (is_small_request(nb)) /* Faster version for small requests */ 2190 { 2191 idx = smallbin_index(nb); 2192 2193 /* No traversal or size check necessary for small bins. */ 2194 2195 q = bin_at(idx); 2196 victim = last(q); 2197 2198 /* Also scan the next one, since it would have a remainder < MINSIZE */ 2199 if (victim == q) 2200 { 2201 q = next_bin(q); 2202 victim = last(q); 2203 } 2204 if (victim != q) 2205 { 2206 victim_size = chunksize(victim); 2207 unlink(victim, bck, fwd); 2208 set_inuse_bit_at_offset(victim, victim_size); 2209 check_malloced_chunk(victim, nb); 2210 return chunk2mem(victim); 2211 } 2212 2213 idx += 2; /* Set for bin scan below. We've already scanned 2 bins. */ 2214 2215 } 2216 else 2217 { 2218 idx = bin_index(nb); 2219 bin = bin_at(idx); 2220 2221 for (victim = last(bin); victim != bin; victim = victim->bk) 2222 { 2223 victim_size = chunksize(victim); 2224 remainder_size = victim_size - nb; 2225 2226 if (remainder_size >= (long)MINSIZE) /* too big */ 2227 { 2228 --idx; /* adjust to rescan below after checking last remainder */ 2229 break; 2230 } 2231 2232 else if (remainder_size >= 0) /* exact fit */ 2233 { 2234 unlink(victim, bck, fwd); 2235 set_inuse_bit_at_offset(victim, victim_size); 2236 check_malloced_chunk(victim, nb); 2237 return chunk2mem(victim); 2238 } 2239 } 2240 2241 ++idx; 2242 2243 } 2244 2245 /* Try to use the last split-off remainder */ 2246 2247 if ( (victim = last_remainder->fd) != last_remainder) 2248 { 2249 victim_size = chunksize(victim); 2250 remainder_size = victim_size - nb; 2251 2252 if (remainder_size >= (long)MINSIZE) /* re-split */ 2253 { 2254 remainder = chunk_at_offset(victim, nb); 2255 set_head(victim, nb | PREV_INUSE); 2256 link_last_remainder(remainder); 2257 set_head(remainder, remainder_size | PREV_INUSE); 2258 set_foot(remainder, remainder_size); 2259 check_malloced_chunk(victim, nb); 2260 return chunk2mem(victim); 2261 } 2262 2263 clear_last_remainder; 2264 2265 if (remainder_size >= 0) /* exhaust */ 2266 { 2267 set_inuse_bit_at_offset(victim, victim_size); 2268 check_malloced_chunk(victim, nb); 2269 return chunk2mem(victim); 2270 } 2271 2272 /* Else place in bin */ 2273 2274 frontlink(victim, victim_size, remainder_index, bck, fwd); 2275 } 2276 2277 /* 2278 If there are any possibly nonempty big-enough blocks, 2279 search for best fitting chunk by scanning bins in blockwidth units. 2280 */ 2281 2282 if ( (block = idx2binblock(idx)) <= binblocks_r) 2283 { 2284 2285 /* Get to the first marked block */ 2286 2287 if ( (block & binblocks_r) == 0) 2288 { 2289 /* force to an even block boundary */ 2290 idx = (idx & ~(BINBLOCKWIDTH - 1)) + BINBLOCKWIDTH; 2291 block <<= 1; 2292 while ((block & binblocks_r) == 0) 2293 { 2294 idx += BINBLOCKWIDTH; 2295 block <<= 1; 2296 } 2297 } 2298 2299 /* For each possibly nonempty block ... */ 2300 for (;;) 2301 { 2302 startidx = idx; /* (track incomplete blocks) */ 2303 q = bin = bin_at(idx); 2304 2305 /* For each bin in this block ... */ 2306 do 2307 { 2308 /* Find and use first big enough chunk ... */ 2309 2310 for (victim = last(bin); victim != bin; victim = victim->bk) 2311 { 2312 victim_size = chunksize(victim); 2313 remainder_size = victim_size - nb; 2314 2315 if (remainder_size >= (long)MINSIZE) /* split */ 2316 { 2317 remainder = chunk_at_offset(victim, nb); 2318 set_head(victim, nb | PREV_INUSE); 2319 unlink(victim, bck, fwd); 2320 link_last_remainder(remainder); 2321 set_head(remainder, remainder_size | PREV_INUSE); 2322 set_foot(remainder, remainder_size); 2323 check_malloced_chunk(victim, nb); 2324 return chunk2mem(victim); 2325 } 2326 2327 else if (remainder_size >= 0) /* take */ 2328 { 2329 set_inuse_bit_at_offset(victim, victim_size); 2330 unlink(victim, bck, fwd); 2331 check_malloced_chunk(victim, nb); 2332 return chunk2mem(victim); 2333 } 2334 2335 } 2336 2337 bin = next_bin(bin); 2338 2339 } while ((++idx & (BINBLOCKWIDTH - 1)) != 0); 2340 2341 /* Clear out the block bit. */ 2342 2343 do /* Possibly backtrack to try to clear a partial block */ 2344 { 2345 if ((startidx & (BINBLOCKWIDTH - 1)) == 0) 2346 { 2347 av_[1] = (mbinptr)(binblocks_r & ~block); 2348 break; 2349 } 2350 --startidx; 2351 q = prev_bin(q); 2352 } while (first(q) == q); 2353 2354 /* Get to the next possibly nonempty block */ 2355 2356 if ( (block <<= 1) <= binblocks_r && (block != 0) ) 2357 { 2358 while ((block & binblocks_r) == 0) 2359 { 2360 idx += BINBLOCKWIDTH; 2361 block <<= 1; 2362 } 2363 } 2364 else 2365 break; 2366 } 2367 } 2368 2369 2370 /* Try to use top chunk */ 2371 2372 /* Require that there be a remainder, ensuring top always exists */ 2373 if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE) 2374 { 2375 2376 #if HAVE_MMAP 2377 /* If big and would otherwise need to extend, try to use mmap instead */ 2378 if ((unsigned long)nb >= (unsigned long)mmap_threshold && 2379 (victim = mmap_chunk(nb)) != 0) 2380 return chunk2mem(victim); 2381 #endif 2382 2383 /* Try to extend */ 2384 malloc_extend_top(nb); 2385 if ( (remainder_size = chunksize(top) - nb) < (long)MINSIZE) 2386 return NULL; /* propagate failure */ 2387 } 2388 2389 victim = top; 2390 set_head(victim, nb | PREV_INUSE); 2391 top = chunk_at_offset(victim, nb); 2392 set_head(top, remainder_size | PREV_INUSE); 2393 check_malloced_chunk(victim, nb); 2394 return chunk2mem(victim); 2395 2396 } 2397 2398 2399 2400 2401 /* 2402 2403 free() algorithm : 2404 2405 cases: 2406 2407 1. free(0) has no effect. 2408 2409 2. If the chunk was allocated via mmap, it is release via munmap(). 2410 2411 3. If a returned chunk borders the current high end of memory, 2412 it is consolidated into the top, and if the total unused 2413 topmost memory exceeds the trim threshold, malloc_trim is 2414 called. 2415 2416 4. Other chunks are consolidated as they arrive, and 2417 placed in corresponding bins. (This includes the case of 2418 consolidating with the current `last_remainder'). 2419 2420 */ 2421 2422 2423 #if __STD_C 2424 void fREe(Void_t* mem) 2425 #else 2426 void fREe(mem) Void_t* mem; 2427 #endif 2428 { 2429 mchunkptr p; /* chunk corresponding to mem */ 2430 INTERNAL_SIZE_T hd; /* its head field */ 2431 INTERNAL_SIZE_T sz; /* its size */ 2432 int idx; /* its bin index */ 2433 mchunkptr next; /* next contiguous chunk */ 2434 INTERNAL_SIZE_T nextsz; /* its size */ 2435 INTERNAL_SIZE_T prevsz; /* size of previous contiguous chunk */ 2436 mchunkptr bck; /* misc temp for linking */ 2437 mchunkptr fwd; /* misc temp for linking */ 2438 int islr; /* track whether merging with last_remainder */ 2439 2440 if (mem == NULL) /* free(0) has no effect */ 2441 return; 2442 2443 p = mem2chunk(mem); 2444 hd = p->size; 2445 2446 #if HAVE_MMAP 2447 if (hd & IS_MMAPPED) /* release mmapped memory. */ 2448 { 2449 munmap_chunk(p); 2450 return; 2451 } 2452 #endif 2453 2454 check_inuse_chunk(p); 2455 2456 sz = hd & ~PREV_INUSE; 2457 next = chunk_at_offset(p, sz); 2458 nextsz = chunksize(next); 2459 2460 if (next == top) /* merge with top */ 2461 { 2462 sz += nextsz; 2463 2464 if (!(hd & PREV_INUSE)) /* consolidate backward */ 2465 { 2466 prevsz = p->prev_size; 2467 p = chunk_at_offset(p, -((long) prevsz)); 2468 sz += prevsz; 2469 unlink(p, bck, fwd); 2470 } 2471 2472 set_head(p, sz | PREV_INUSE); 2473 top = p; 2474 if ((unsigned long)(sz) >= (unsigned long)trim_threshold) 2475 malloc_trim(top_pad); 2476 return; 2477 } 2478 2479 set_head(next, nextsz); /* clear inuse bit */ 2480 2481 islr = 0; 2482 2483 if (!(hd & PREV_INUSE)) /* consolidate backward */ 2484 { 2485 prevsz = p->prev_size; 2486 p = chunk_at_offset(p, -((long) prevsz)); 2487 sz += prevsz; 2488 2489 if (p->fd == last_remainder) /* keep as last_remainder */ 2490 islr = 1; 2491 else 2492 unlink(p, bck, fwd); 2493 } 2494 2495 if (!(inuse_bit_at_offset(next, nextsz))) /* consolidate forward */ 2496 { 2497 sz += nextsz; 2498 2499 if (!islr && next->fd == last_remainder) /* re-insert last_remainder */ 2500 { 2501 islr = 1; 2502 link_last_remainder(p); 2503 } 2504 else 2505 unlink(next, bck, fwd); 2506 } 2507 2508 2509 set_head(p, sz | PREV_INUSE); 2510 set_foot(p, sz); 2511 if (!islr) 2512 frontlink(p, sz, idx, bck, fwd); 2513 } 2514 2515 2516 2517 2518 2519 /* 2520 2521 Realloc algorithm: 2522 2523 Chunks that were obtained via mmap cannot be extended or shrunk 2524 unless HAVE_MREMAP is defined, in which case mremap is used. 2525 Otherwise, if their reallocation is for additional space, they are 2526 copied. If for less, they are just left alone. 2527 2528 Otherwise, if the reallocation is for additional space, and the 2529 chunk can be extended, it is, else a malloc-copy-free sequence is 2530 taken. There are several different ways that a chunk could be 2531 extended. All are tried: 2532 2533 * Extending forward into following adjacent free chunk. 2534 * Shifting backwards, joining preceding adjacent space 2535 * Both shifting backwards and extending forward. 2536 * Extending into newly sbrked space 2537 2538 Unless the #define REALLOC_ZERO_BYTES_FREES is set, realloc with a 2539 size argument of zero (re)allocates a minimum-sized chunk. 2540 2541 If the reallocation is for less space, and the new request is for 2542 a `small' (<512 bytes) size, then the newly unused space is lopped 2543 off and freed. 2544 2545 The old unix realloc convention of allowing the last-free'd chunk 2546 to be used as an argument to realloc is no longer supported. 2547 I don't know of any programs still relying on this feature, 2548 and allowing it would also allow too many other incorrect 2549 usages of realloc to be sensible. 2550 2551 2552 */ 2553 2554 2555 #if __STD_C 2556 Void_t* rEALLOc(Void_t* oldmem, size_t bytes) 2557 #else 2558 Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes; 2559 #endif 2560 { 2561 INTERNAL_SIZE_T nb; /* padded request size */ 2562 2563 mchunkptr oldp; /* chunk corresponding to oldmem */ 2564 INTERNAL_SIZE_T oldsize; /* its size */ 2565 2566 mchunkptr newp; /* chunk to return */ 2567 INTERNAL_SIZE_T newsize; /* its size */ 2568 Void_t* newmem; /* corresponding user mem */ 2569 2570 mchunkptr next; /* next contiguous chunk after oldp */ 2571 INTERNAL_SIZE_T nextsize; /* its size */ 2572 2573 mchunkptr prev; /* previous contiguous chunk before oldp */ 2574 INTERNAL_SIZE_T prevsize; /* its size */ 2575 2576 mchunkptr remainder; /* holds split off extra space from newp */ 2577 INTERNAL_SIZE_T remainder_size; /* its size */ 2578 2579 mchunkptr bck; /* misc temp for linking */ 2580 mchunkptr fwd; /* misc temp for linking */ 2581 2582 #ifdef REALLOC_ZERO_BYTES_FREES 2583 if (bytes == 0) { fREe(oldmem); return 0; } 2584 #endif 2585 2586 if ((long)bytes < 0) return NULL; 2587 2588 /* realloc of null is supposed to be same as malloc */ 2589 if (oldmem == NULL) return mALLOc(bytes); 2590 2591 newp = oldp = mem2chunk(oldmem); 2592 newsize = oldsize = chunksize(oldp); 2593 2594 2595 nb = request2size(bytes); 2596 2597 #if HAVE_MMAP 2598 if (chunk_is_mmapped(oldp)) 2599 { 2600 #if HAVE_MREMAP 2601 newp = mremap_chunk(oldp, nb); 2602 if(newp) return chunk2mem(newp); 2603 #endif 2604 /* Note the extra SIZE_SZ overhead. */ 2605 if(oldsize - SIZE_SZ >= nb) return oldmem; /* do nothing */ 2606 /* Must alloc, copy, free. */ 2607 newmem = mALLOc(bytes); 2608 if (newmem == 0) return 0; /* propagate failure */ 2609 MALLOC_COPY(newmem, oldmem, oldsize - 2*SIZE_SZ); 2610 munmap_chunk(oldp); 2611 return newmem; 2612 } 2613 #endif 2614 2615 check_inuse_chunk(oldp); 2616 2617 if ((long)(oldsize) < (long)(nb)) 2618 { 2619 2620 /* Try expanding forward */ 2621 2622 next = chunk_at_offset(oldp, oldsize); 2623 if (next == top || !inuse(next)) 2624 { 2625 nextsize = chunksize(next); 2626 2627 /* Forward into top only if a remainder */ 2628 if (next == top) 2629 { 2630 if ((long)(nextsize + newsize) >= (long)(nb + MINSIZE)) 2631 { 2632 newsize += nextsize; 2633 top = chunk_at_offset(oldp, nb); 2634 set_head(top, (newsize - nb) | PREV_INUSE); 2635 set_head_size(oldp, nb); 2636 return chunk2mem(oldp); 2637 } 2638 } 2639 2640 /* Forward into next chunk */ 2641 else if (((long)(nextsize + newsize) >= (long)(nb))) 2642 { 2643 unlink(next, bck, fwd); 2644 newsize += nextsize; 2645 goto split; 2646 } 2647 } 2648 else 2649 { 2650 next = NULL; 2651 nextsize = 0; 2652 } 2653 2654 /* Try shifting backwards. */ 2655 2656 if (!prev_inuse(oldp)) 2657 { 2658 prev = prev_chunk(oldp); 2659 prevsize = chunksize(prev); 2660 2661 /* try forward + backward first to save a later consolidation */ 2662 2663 if (next != NULL) 2664 { 2665 /* into top */ 2666 if (next == top) 2667 { 2668 if ((long)(nextsize + prevsize + newsize) >= (long)(nb + MINSIZE)) 2669 { 2670 unlink(prev, bck, fwd); 2671 newp = prev; 2672 newsize += prevsize + nextsize; 2673 newmem = chunk2mem(newp); 2674 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); 2675 top = chunk_at_offset(newp, nb); 2676 set_head(top, (newsize - nb) | PREV_INUSE); 2677 set_head_size(newp, nb); 2678 return newmem; 2679 } 2680 } 2681 2682 /* into next chunk */ 2683 else if (((long)(nextsize + prevsize + newsize) >= (long)(nb))) 2684 { 2685 unlink(next, bck, fwd); 2686 unlink(prev, bck, fwd); 2687 newp = prev; 2688 newsize += nextsize + prevsize; 2689 newmem = chunk2mem(newp); 2690 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); 2691 goto split; 2692 } 2693 } 2694 2695 /* backward only */ 2696 if (prev != NULL && (long)(prevsize + newsize) >= (long)nb) 2697 { 2698 unlink(prev, bck, fwd); 2699 newp = prev; 2700 newsize += prevsize; 2701 newmem = chunk2mem(newp); 2702 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); 2703 goto split; 2704 } 2705 } 2706 2707 /* Must allocate */ 2708 2709 newmem = mALLOc (bytes); 2710 2711 if (newmem == NULL) /* propagate failure */ 2712 return NULL; 2713 2714 /* Avoid copy if newp is next chunk after oldp. */ 2715 /* (This can only happen when new chunk is sbrk'ed.) */ 2716 2717 if ( (newp = mem2chunk(newmem)) == next_chunk(oldp)) 2718 { 2719 newsize += chunksize(newp); 2720 newp = oldp; 2721 goto split; 2722 } 2723 2724 /* Otherwise copy, free, and exit */ 2725 MALLOC_COPY(newmem, oldmem, oldsize - SIZE_SZ); 2726 fREe(oldmem); 2727 return newmem; 2728 } 2729 2730 2731 split: /* split off extra room in old or expanded chunk */ 2732 2733 if (newsize - nb >= MINSIZE) /* split off remainder */ 2734 { 2735 remainder = chunk_at_offset(newp, nb); 2736 remainder_size = newsize - nb; 2737 set_head_size(newp, nb); 2738 set_head(remainder, remainder_size | PREV_INUSE); 2739 set_inuse_bit_at_offset(remainder, remainder_size); 2740 fREe(chunk2mem(remainder)); /* let free() deal with it */ 2741 } 2742 else 2743 { 2744 set_head_size(newp, newsize); 2745 set_inuse_bit_at_offset(newp, newsize); 2746 } 2747 2748 check_inuse_chunk(newp); 2749 return chunk2mem(newp); 2750 } 2751 2752 2753 2754 2755 /* 2756 2757 memalign algorithm: 2758 2759 memalign requests more than enough space from malloc, finds a spot 2760 within that chunk that meets the alignment request, and then 2761 possibly frees the leading and trailing space. 2762 2763 The alignment argument must be a power of two. This property is not 2764 checked by memalign, so misuse may result in random runtime errors. 2765 2766 8-byte alignment is guaranteed by normal malloc calls, so don't 2767 bother calling memalign with an argument of 8 or less. 2768 2769 Overreliance on memalign is a sure way to fragment space. 2770 2771 */ 2772 2773 2774 #if __STD_C 2775 Void_t* mEMALIGn(size_t alignment, size_t bytes) 2776 #else 2777 Void_t* mEMALIGn(alignment, bytes) size_t alignment; size_t bytes; 2778 #endif 2779 { 2780 INTERNAL_SIZE_T nb; /* padded request size */ 2781 char* m; /* memory returned by malloc call */ 2782 mchunkptr p; /* corresponding chunk */ 2783 char* brk; /* alignment point within p */ 2784 mchunkptr newp; /* chunk to return */ 2785 INTERNAL_SIZE_T newsize; /* its size */ 2786 INTERNAL_SIZE_T leadsize; /* leading space befor alignment point */ 2787 mchunkptr remainder; /* spare room at end to split off */ 2788 long remainder_size; /* its size */ 2789 2790 if ((long)bytes < 0) return NULL; 2791 2792 /* If need less alignment than we give anyway, just relay to malloc */ 2793 2794 if (alignment <= MALLOC_ALIGNMENT) return mALLOc(bytes); 2795 2796 /* Otherwise, ensure that it is at least a minimum chunk size */ 2797 2798 if (alignment < MINSIZE) alignment = MINSIZE; 2799 2800 /* Call malloc with worst case padding to hit alignment. */ 2801 2802 nb = request2size(bytes); 2803 m = (char*)(mALLOc(nb + alignment + MINSIZE)); 2804 2805 if (m == NULL) return NULL; /* propagate failure */ 2806 2807 p = mem2chunk(m); 2808 2809 if ((((unsigned long)(m)) % alignment) == 0) /* aligned */ 2810 { 2811 #if HAVE_MMAP 2812 if(chunk_is_mmapped(p)) 2813 return chunk2mem(p); /* nothing more to do */ 2814 #endif 2815 } 2816 else /* misaligned */ 2817 { 2818 /* 2819 Find an aligned spot inside chunk. 2820 Since we need to give back leading space in a chunk of at 2821 least MINSIZE, if the first calculation places us at 2822 a spot with less than MINSIZE leader, we can move to the 2823 next aligned spot -- we've allocated enough total room so that 2824 this is always possible. 2825 */ 2826 2827 brk = (char*)mem2chunk(((unsigned long)(m + alignment - 1)) & -((signed) alignment)); 2828 if ((long)(brk - (char*)(p)) < MINSIZE) brk = brk + alignment; 2829 2830 newp = (mchunkptr)brk; 2831 leadsize = brk - (char*)(p); 2832 newsize = chunksize(p) - leadsize; 2833 2834 #if HAVE_MMAP 2835 if(chunk_is_mmapped(p)) 2836 { 2837 newp->prev_size = p->prev_size + leadsize; 2838 set_head(newp, newsize|IS_MMAPPED); 2839 return chunk2mem(newp); 2840 } 2841 #endif 2842 2843 /* give back leader, use the rest */ 2844 2845 set_head(newp, newsize | PREV_INUSE); 2846 set_inuse_bit_at_offset(newp, newsize); 2847 set_head_size(p, leadsize); 2848 fREe(chunk2mem(p)); 2849 p = newp; 2850 2851 assert (newsize >= nb && (((unsigned long)(chunk2mem(p))) % alignment) == 0); 2852 } 2853 2854 /* Also give back spare room at the end */ 2855 2856 remainder_size = chunksize(p) - nb; 2857 2858 if (remainder_size >= (long)MINSIZE) 2859 { 2860 remainder = chunk_at_offset(p, nb); 2861 set_head(remainder, remainder_size | PREV_INUSE); 2862 set_head_size(p, nb); 2863 fREe(chunk2mem(remainder)); 2864 } 2865 2866 check_inuse_chunk(p); 2867 return chunk2mem(p); 2868 2869 } 2870 2871 2872 2873 2874 /* 2875 valloc just invokes memalign with alignment argument equal 2876 to the page size of the system (or as near to this as can 2877 be figured out from all the includes/defines above.) 2878 */ 2879 2880 #if __STD_C 2881 Void_t* vALLOc(size_t bytes) 2882 #else 2883 Void_t* vALLOc(bytes) size_t bytes; 2884 #endif 2885 { 2886 return mEMALIGn (malloc_getpagesize, bytes); 2887 } 2888 2889 /* 2890 pvalloc just invokes valloc for the nearest pagesize 2891 that will accommodate request 2892 */ 2893 2894 2895 #if __STD_C 2896 Void_t* pvALLOc(size_t bytes) 2897 #else 2898 Void_t* pvALLOc(bytes) size_t bytes; 2899 #endif 2900 { 2901 size_t pagesize = malloc_getpagesize; 2902 return mEMALIGn (pagesize, (bytes + pagesize - 1) & ~(pagesize - 1)); 2903 } 2904 2905 /* 2906 2907 calloc calls malloc, then zeroes out the allocated chunk. 2908 2909 */ 2910 2911 #if __STD_C 2912 Void_t* cALLOc(size_t n, size_t elem_size) 2913 #else 2914 Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size; 2915 #endif 2916 { 2917 mchunkptr p; 2918 INTERNAL_SIZE_T csz; 2919 2920 INTERNAL_SIZE_T sz = n * elem_size; 2921 2922 2923 /* check if expand_top called, in which case don't need to clear */ 2924 #if MORECORE_CLEARS 2925 mchunkptr oldtop = top; 2926 INTERNAL_SIZE_T oldtopsize = chunksize(top); 2927 #endif 2928 Void_t* mem = mALLOc (sz); 2929 2930 if ((long)n < 0) return NULL; 2931 2932 if (mem == NULL) 2933 return NULL; 2934 else 2935 { 2936 p = mem2chunk(mem); 2937 2938 /* Two optional cases in which clearing not necessary */ 2939 2940 2941 #if HAVE_MMAP 2942 if (chunk_is_mmapped(p)) return mem; 2943 #endif 2944 2945 csz = chunksize(p); 2946 2947 #if MORECORE_CLEARS 2948 if (p == oldtop && csz > oldtopsize) 2949 { 2950 /* clear only the bytes from non-freshly-sbrked memory */ 2951 csz = oldtopsize; 2952 } 2953 #endif 2954 2955 MALLOC_ZERO(mem, csz - SIZE_SZ); 2956 return mem; 2957 } 2958 } 2959 2960 /* 2961 2962 cfree just calls free. It is needed/defined on some systems 2963 that pair it with calloc, presumably for odd historical reasons. 2964 2965 */ 2966 2967 #if !defined(INTERNAL_LINUX_C_LIB) || !defined(__ELF__) 2968 #if __STD_C 2969 void cfree(Void_t *mem) 2970 #else 2971 void cfree(mem) Void_t *mem; 2972 #endif 2973 { 2974 fREe(mem); 2975 } 2976 #endif 2977 2978 2979 2980 /* 2981 2982 Malloc_trim gives memory back to the system (via negative 2983 arguments to sbrk) if there is unused memory at the `high' end of 2984 the malloc pool. You can call this after freeing large blocks of 2985 memory to potentially reduce the system-level memory requirements 2986 of a program. However, it cannot guarantee to reduce memory. Under 2987 some allocation patterns, some large free blocks of memory will be 2988 locked between two used chunks, so they cannot be given back to 2989 the system. 2990 2991 The `pad' argument to malloc_trim represents the amount of free 2992 trailing space to leave untrimmed. If this argument is zero, 2993 only the minimum amount of memory to maintain internal data 2994 structures will be left (one page or less). Non-zero arguments 2995 can be supplied to maintain enough trailing space to service 2996 future expected allocations without having to re-obtain memory 2997 from the system. 2998 2999 Malloc_trim returns 1 if it actually released any memory, else 0. 3000 3001 */ 3002 3003 #if __STD_C 3004 int malloc_trim(size_t pad) 3005 #else 3006 int malloc_trim(pad) size_t pad; 3007 #endif 3008 { 3009 long top_size; /* Amount of top-most memory */ 3010 long extra; /* Amount to release */ 3011 char* current_brk; /* address returned by pre-check sbrk call */ 3012 char* new_brk; /* address returned by negative sbrk call */ 3013 3014 unsigned long pagesz = malloc_getpagesize; 3015 3016 top_size = chunksize(top); 3017 extra = ((top_size - pad - MINSIZE + (pagesz-1)) / pagesz - 1) * pagesz; 3018 3019 if (extra < (long)pagesz) /* Not enough memory to release */ 3020 return 0; 3021 3022 else 3023 { 3024 /* Test to make sure no one else called sbrk */ 3025 current_brk = (char*)(MORECORE (0)); 3026 if (current_brk != (char*)(top) + top_size) 3027 return 0; /* Apparently we don't own memory; must fail */ 3028 3029 else 3030 { 3031 new_brk = (char*)(MORECORE (-extra)); 3032 3033 if (new_brk == (char*)(MORECORE_FAILURE)) /* sbrk failed? */ 3034 { 3035 /* Try to figure out what we have */ 3036 current_brk = (char*)(MORECORE (0)); 3037 top_size = current_brk - (char*)top; 3038 if (top_size >= (long)MINSIZE) /* if not, we are very very dead! */ 3039 { 3040 sbrked_mem = current_brk - sbrk_base; 3041 set_head(top, top_size | PREV_INUSE); 3042 } 3043 check_chunk(top); 3044 return 0; 3045 } 3046 3047 else 3048 { 3049 /* Success. Adjust top accordingly. */ 3050 set_head(top, (top_size - extra) | PREV_INUSE); 3051 sbrked_mem -= extra; 3052 check_chunk(top); 3053 return 1; 3054 } 3055 } 3056 } 3057 } 3058 3059 3060 3061 /* 3062 malloc_usable_size: 3063 3064 This routine tells you how many bytes you can actually use in an 3065 allocated chunk, which may be more than you requested (although 3066 often not). You can use this many bytes without worrying about 3067 overwriting other allocated objects. Not a particularly great 3068 programming practice, but still sometimes useful. 3069 3070 */ 3071 3072 #if __STD_C 3073 size_t malloc_usable_size(Void_t* mem) 3074 #else 3075 size_t malloc_usable_size(mem) Void_t* mem; 3076 #endif 3077 { 3078 mchunkptr p; 3079 if (mem == NULL) 3080 return 0; 3081 else 3082 { 3083 p = mem2chunk(mem); 3084 if(!chunk_is_mmapped(p)) 3085 { 3086 if (!inuse(p)) return 0; 3087 check_inuse_chunk(p); 3088 return chunksize(p) - SIZE_SZ; 3089 } 3090 return chunksize(p) - 2*SIZE_SZ; 3091 } 3092 } 3093 3094 3095 3096 3097 /* Utility to update current_mallinfo for malloc_stats and mallinfo() */ 3098 3099 #ifdef DEBUG 3100 static void malloc_update_mallinfo() 3101 { 3102 int i; 3103 mbinptr b; 3104 mchunkptr p; 3105 #ifdef DEBUG 3106 mchunkptr q; 3107 #endif 3108 3109 INTERNAL_SIZE_T avail = chunksize(top); 3110 int navail = ((long)(avail) >= (long)MINSIZE)? 1 : 0; 3111 3112 for (i = 1; i < NAV; ++i) 3113 { 3114 b = bin_at(i); 3115 for (p = last(b); p != b; p = p->bk) 3116 { 3117 #ifdef DEBUG 3118 check_free_chunk(p); 3119 for (q = next_chunk(p); 3120 q < top && inuse(q) && (long)(chunksize(q)) >= (long)MINSIZE; 3121 q = next_chunk(q)) 3122 check_inuse_chunk(q); 3123 #endif 3124 avail += chunksize(p); 3125 navail++; 3126 } 3127 } 3128 3129 current_mallinfo.ordblks = navail; 3130 current_mallinfo.uordblks = sbrked_mem - avail; 3131 current_mallinfo.fordblks = avail; 3132 current_mallinfo.hblks = n_mmaps; 3133 current_mallinfo.hblkhd = mmapped_mem; 3134 current_mallinfo.keepcost = chunksize(top); 3135 3136 } 3137 #endif /* DEBUG */ 3138 3139 3140 3141 /* 3142 3143 malloc_stats: 3144 3145 Prints on the amount of space obtain from the system (both 3146 via sbrk and mmap), the maximum amount (which may be more than 3147 current if malloc_trim and/or munmap got called), the maximum 3148 number of simultaneous mmap regions used, and the current number 3149 of bytes allocated via malloc (or realloc, etc) but not yet 3150 freed. (Note that this is the number of bytes allocated, not the 3151 number requested. It will be larger than the number requested 3152 because of alignment and bookkeeping overhead.) 3153 3154 */ 3155 3156 #ifdef DEBUG 3157 void malloc_stats() 3158 { 3159 malloc_update_mallinfo(); 3160 printf("max system bytes = %10u\n", 3161 (unsigned int)(max_total_mem)); 3162 printf("system bytes = %10u\n", 3163 (unsigned int)(sbrked_mem + mmapped_mem)); 3164 printf("in use bytes = %10u\n", 3165 (unsigned int)(current_mallinfo.uordblks + mmapped_mem)); 3166 #if HAVE_MMAP 3167 printf("max mmap regions = %10u\n", 3168 (unsigned int)max_n_mmaps); 3169 #endif 3170 } 3171 #endif /* DEBUG */ 3172 3173 /* 3174 mallinfo returns a copy of updated current mallinfo. 3175 */ 3176 3177 #ifdef DEBUG 3178 struct mallinfo mALLINFo() 3179 { 3180 malloc_update_mallinfo(); 3181 return current_mallinfo; 3182 } 3183 #endif /* DEBUG */ 3184 3185 3186 3187 3188 /* 3189 mallopt: 3190 3191 mallopt is the general SVID/XPG interface to tunable parameters. 3192 The format is to provide a (parameter-number, parameter-value) pair. 3193 mallopt then sets the corresponding parameter to the argument 3194 value if it can (i.e., so long as the value is meaningful), 3195 and returns 1 if successful else 0. 3196 3197 See descriptions of tunable parameters above. 3198 3199 */ 3200 3201 #if __STD_C 3202 int mALLOPt(int param_number, int value) 3203 #else 3204 int mALLOPt(param_number, value) int param_number; int value; 3205 #endif 3206 { 3207 switch(param_number) 3208 { 3209 case M_TRIM_THRESHOLD: 3210 trim_threshold = value; return 1; 3211 case M_TOP_PAD: 3212 top_pad = value; return 1; 3213 case M_MMAP_THRESHOLD: 3214 mmap_threshold = value; return 1; 3215 case M_MMAP_MAX: 3216 #if HAVE_MMAP 3217 n_mmaps_max = value; return 1; 3218 #else 3219 if (value != 0) return 0; else n_mmaps_max = value; return 1; 3220 #endif 3221 3222 default: 3223 return 0; 3224 } 3225 } 3226 3227 /* 3228 3229 History: 3230 3231 V2.6.6 Sun Dec 5 07:42:19 1999 Doug Lea (dl at gee) 3232 * return null for negative arguments 3233 * Added Several WIN32 cleanups from Martin C. Fong <mcfong@yahoo.com> 3234 * Add 'LACKS_SYS_PARAM_H' for those systems without 'sys/param.h' 3235 (e.g. WIN32 platforms) 3236 * Cleanup up header file inclusion for WIN32 platforms 3237 * Cleanup code to avoid Microsoft Visual C++ compiler complaints 3238 * Add 'USE_DL_PREFIX' to quickly allow co-existence with existing 3239 memory allocation routines 3240 * Set 'malloc_getpagesize' for WIN32 platforms (needs more work) 3241 * Use 'assert' rather than 'ASSERT' in WIN32 code to conform to 3242 usage of 'assert' in non-WIN32 code 3243 * Improve WIN32 'sbrk()' emulation's 'findRegion()' routine to 3244 avoid infinite loop 3245 * Always call 'fREe()' rather than 'free()' 3246 3247 V2.6.5 Wed Jun 17 15:57:31 1998 Doug Lea (dl at gee) 3248 * Fixed ordering problem with boundary-stamping 3249 3250 V2.6.3 Sun May 19 08:17:58 1996 Doug Lea (dl at gee) 3251 * Added pvalloc, as recommended by H.J. Liu 3252 * Added 64bit pointer support mainly from Wolfram Gloger 3253 * Added anonymously donated WIN32 sbrk emulation 3254 * Malloc, calloc, getpagesize: add optimizations from Raymond Nijssen 3255 * malloc_extend_top: fix mask error that caused wastage after 3256 foreign sbrks 3257 * Add linux mremap support code from HJ Liu 3258 3259 V2.6.2 Tue Dec 5 06:52:55 1995 Doug Lea (dl at gee) 3260 * Integrated most documentation with the code. 3261 * Add support for mmap, with help from 3262 Wolfram Gloger (Gloger@lrz.uni-muenchen.de). 3263 * Use last_remainder in more cases. 3264 * Pack bins using idea from colin@nyx10.cs.du.edu 3265 * Use ordered bins instead of best-fit threshhold 3266 * Eliminate block-local decls to simplify tracing and debugging. 3267 * Support another case of realloc via move into top 3268 * Fix error occuring when initial sbrk_base not word-aligned. 3269 * Rely on page size for units instead of SBRK_UNIT to 3270 avoid surprises about sbrk alignment conventions. 3271 * Add mallinfo, mallopt. Thanks to Raymond Nijssen 3272 (raymond@es.ele.tue.nl) for the suggestion. 3273 * Add `pad' argument to malloc_trim and top_pad mallopt parameter. 3274 * More precautions for cases where other routines call sbrk, 3275 courtesy of Wolfram Gloger (Gloger@lrz.uni-muenchen.de). 3276 * Added macros etc., allowing use in linux libc from 3277 H.J. Lu (hjl@gnu.ai.mit.edu) 3278 * Inverted this history list 3279 3280 V2.6.1 Sat Dec 2 14:10:57 1995 Doug Lea (dl at gee) 3281 * Re-tuned and fixed to behave more nicely with V2.6.0 changes. 3282 * Removed all preallocation code since under current scheme 3283 the work required to undo bad preallocations exceeds 3284 the work saved in good cases for most test programs. 3285 * No longer use return list or unconsolidated bins since 3286 no scheme using them consistently outperforms those that don't 3287 given above changes. 3288 * Use best fit for very large chunks to prevent some worst-cases. 3289 * Added some support for debugging 3290 3291 V2.6.0 Sat Nov 4 07:05:23 1995 Doug Lea (dl at gee) 3292 * Removed footers when chunks are in use. Thanks to 3293 Paul Wilson (wilson@cs.texas.edu) for the suggestion. 3294 3295 V2.5.4 Wed Nov 1 07:54:51 1995 Doug Lea (dl at gee) 3296 * Added malloc_trim, with help from Wolfram Gloger 3297 (wmglo@Dent.MED.Uni-Muenchen.DE). 3298 3299 V2.5.3 Tue Apr 26 10:16:01 1994 Doug Lea (dl at g) 3300 3301 V2.5.2 Tue Apr 5 16:20:40 1994 Doug Lea (dl at g) 3302 * realloc: try to expand in both directions 3303 * malloc: swap order of clean-bin strategy; 3304 * realloc: only conditionally expand backwards 3305 * Try not to scavenge used bins 3306 * Use bin counts as a guide to preallocation 3307 * Occasionally bin return list chunks in first scan 3308 * Add a few optimizations from colin@nyx10.cs.du.edu 3309 3310 V2.5.1 Sat Aug 14 15:40:43 1993 Doug Lea (dl at g) 3311 * faster bin computation & slightly different binning 3312 * merged all consolidations to one part of malloc proper 3313 (eliminating old malloc_find_space & malloc_clean_bin) 3314 * Scan 2 returns chunks (not just 1) 3315 * Propagate failure in realloc if malloc returns 0 3316 * Add stuff to allow compilation on non-ANSI compilers 3317 from kpv@research.att.com 3318 3319 V2.5 Sat Aug 7 07:41:59 1993 Doug Lea (dl at g.oswego.edu) 3320 * removed potential for odd address access in prev_chunk 3321 * removed dependency on getpagesize.h 3322 * misc cosmetics and a bit more internal documentation 3323 * anticosmetics: mangled names in macros to evade debugger strangeness 3324 * tested on sparc, hp-700, dec-mips, rs6000 3325 with gcc & native cc (hp, dec only) allowing 3326 Detlefs & Zorn comparison study (in SIGPLAN Notices.) 3327 3328 Trial version Fri Aug 28 13:14:29 1992 Doug Lea (dl at g.oswego.edu) 3329 * Based loosely on libg++-1.2X malloc. (It retains some of the overall 3330 structure of old version, but most details differ.) 3331 3332 */ 3333