include/malloc.h

   1 /*
   2   A version of malloc/free/realloc written by Doug Lea and released to the
   3   public domain.  Send questions/comments/complaints/performance data
   4   to dl@cs.oswego.edu
   5
   6 * VERSION 2.6.6  Sun Mar  5 19:10:03 2000  Doug Lea  (dl at gee)
   7
   8    Note: There may be an updated version of this malloc obtainable at
   9            ftp://g.oswego.edu/pub/misc/malloc.c
  10          Check before installing!
  11
  12 * Why use this malloc?
  13
  14   This is not the fastest, most space-conserving, most portable, or
  15   most tunable malloc ever written. However it is among the fastest
  16   while also being among the most space-conserving, portable and tunable.
  17   Consistent balance across these factors results in a good general-purpose
  18   allocator. For a high-level description, see
  19      http://g.oswego.edu/dl/html/malloc.html
  20
  21 * Synopsis of public routines
  22
  23   (Much fuller descriptions are contained in the program documentation below.)
  24
  25   malloc(size_t n);
  26      Return a pointer to a newly allocated chunk of at least n bytes, or null
  27      if no space is available.
  28   free(Void_t* p);
  29      Release the chunk of memory pointed to by p, or no effect if p is null.
  30   realloc(Void_t* p, size_t n);
  31      Return a pointer to a chunk of size n that contains the same data
  32      as does chunk p up to the minimum of (n, p's size) bytes, or null
  33      if no space is available. The returned pointer may or may not be
  34      the same as p. If p is null, equivalent to malloc.  Unless the
  35      #define REALLOC_ZERO_BYTES_FREES below is set, realloc with a
  36      size argument of zero (re)allocates a minimum-sized chunk.
  37   memalign(size_t alignment, size_t n);
  38      Return a pointer to a newly allocated chunk of n bytes, aligned
  39      in accord with the alignment argument, which must be a power of
  40      two.
  41   valloc(size_t n);
  42      Equivalent to memalign(pagesize, n), where pagesize is the page
  43      size of the system (or as near to this as can be figured out from
  44      all the includes/defines below.)
  45   pvalloc(size_t n);
  46      Equivalent to valloc(minimum-page-that-holds(n)), that is,
  47      round up n to nearest pagesize.
  48   calloc(size_t unit, size_t quantity);
  49      Returns a pointer to quantity * unit bytes, with all locations
  50      set to zero.
  51   cfree(Void_t* p);
  52      Equivalent to free(p).
  53   malloc_trim(size_t pad);
  54      Release all but pad bytes of freed top-most memory back
  55      to the system. Return 1 if successful, else 0.
  56   malloc_usable_size(Void_t* p);
  57      Report the number usable allocated bytes associated with allocated
  58      chunk p. This may or may not report more bytes than were requested,
  59      due to alignment and minimum size constraints.
  60   malloc_stats();
  61      Prints brief summary statistics on stderr.
  62   mallinfo()
  63      Returns (by copy) a struct containing various summary statistics.
  64   mallopt(int parameter_number, int parameter_value)
  65      Changes one of the tunable parameters described below. Returns
  66      1 if successful in changing the parameter, else 0.
  67
  68 * Vital statistics:
  69
  70   Alignment:                            8-byte
  71        8 byte alignment is currently hardwired into the design.  This
  72        seems to suffice for all current machines and C compilers.
  73
  74   Assumed pointer representation:       4 or 8 bytes
  75        Code for 8-byte pointers is untested by me but has worked
  76        reliably by Wolfram Gloger, who contributed most of the
  77        changes supporting this.
  78
  79   Assumed size_t  representation:       4 or 8 bytes
  80        Note that size_t is allowed to be 4 bytes even if pointers are 8.
  81
  82   Minimum overhead per allocated chunk: 4 or 8 bytes
  83        Each malloced chunk has a hidden overhead of 4 bytes holding size
  84        and status information.
  85
  86   Minimum allocated size: 4-byte ptrs:  16 bytes    (including 4 overhead)
  87                           8-byte ptrs:  24/32 bytes (including, 4/8 overhead)
  88
  89        When a chunk is freed, 12 (for 4byte ptrs) or 20 (for 8 byte
  90        ptrs but 4 byte size) or 24 (for 8/8) additional bytes are
  91        needed; 4 (8) for a trailing size field
  92        and 8 (16) bytes for free list pointers. Thus, the minimum
  93        allocatable size is 16/24/32 bytes.
  94
  95        Even a request for zero bytes (i.e., malloc(0)) returns a
  96        pointer to something of the minimum allocatable size.
  97
  98   Maximum allocated size: 4-byte size_t: 2^31 -  8 bytes
  99                           8-byte size_t: 2^63 - 16 bytes
 100
 101        It is assumed that (possibly signed) size_t bit values suffice to
 102        represent chunk sizes. `Possibly signed' is due to the fact
 103        that `size_t' may be defined on a system as either a signed or
 104        an unsigned type. To be conservative, values that would appear
 105        as negative numbers are avoided.
 106        Requests for sizes with a negative sign bit when the request
 107        size is treaded as a long will return null.
 108
 109   Maximum overhead wastage per allocated chunk: normally 15 bytes
 110
 111        Alignnment demands, plus the minimum allocatable size restriction
 112        make the normal worst-case wastage 15 bytes (i.e., up to 15
 113        more bytes will be allocated than were requested in malloc), with
 114        two exceptions:
 115          1. Because requests for zero bytes allocate non-zero space,
 116             the worst case wastage for a request of zero bytes is 24 bytes.
 117          2. For requests >= mmap_threshold that are serviced via
 118             mmap(), the worst case wastage is 8 bytes plus the remainder
 119             from a system page (the minimal mmap unit); typically 4096 bytes.
 120
 121 * Limitations
 122
 123     Here are some features that are NOT currently supported
 124
 125     * No user-definable hooks for callbacks and the like.
 126     * No automated mechanism for fully checking that all accesses
 127       to malloced memory stay within their bounds.
 128     * No support for compaction.
 129
 130 * Synopsis of compile-time options:
 131
 132     People have reported using previous versions of this malloc on all
 133     versions of Unix, sometimes by tweaking some of the defines
 134     below. It has been tested most extensively on Solaris and
 135     Linux. It is also reported to work on WIN32 platforms.
 136     People have also reported adapting this malloc for use in
 137     stand-alone embedded systems.
 138
 139     The implementation is in straight, hand-tuned ANSI C.  Among other
 140     consequences, it uses a lot of macros.  Because of this, to be at
 141     all usable, this code should be compiled using an optimizing compiler
 142     (for example gcc -O2) that can simplify expressions and control
 143     paths.
 144
 145   __STD_C                  (default: derived from C compiler defines)
 146      Nonzero if using ANSI-standard C compiler, a C++ compiler, or
 147      a C compiler sufficiently close to ANSI to get away with it.
 148   DEBUG                    (default: NOT defined)
 149      Define to enable debugging. Adds fairly extensive assertion-based
 150      checking to help track down memory errors, but noticeably slows down
 151      execution.
 152   REALLOC_ZERO_BYTES_FREES (default: NOT defined)
 153      Define this if you think that realloc(p, 0) should be equivalent
 154      to free(p). Otherwise, since malloc returns a unique pointer for
 155      malloc(0), so does realloc(p, 0).
 156   HAVE_MEMCPY               (default: defined)
 157      Define if you are not otherwise using ANSI STD C, but still
 158      have memcpy and memset in your C library and want to use them.
 159      Otherwise, simple internal versions are supplied.
 160   USE_MEMCPY               (default: 1 if HAVE_MEMCPY is defined, 0 otherwise)
 161      Define as 1 if you want the C library versions of memset and
 162      memcpy called in realloc and calloc (otherwise macro versions are used).
 163      At least on some platforms, the simple macro versions usually
 164      outperform libc versions.
 165   HAVE_MMAP                 (default: defined as 1)
 166      Define to non-zero to optionally make malloc() use mmap() to
 167      allocate very large blocks.
 168   HAVE_MREMAP                 (default: defined as 0 unless Linux libc set)
 169      Define to non-zero to optionally make realloc() use mremap() to
 170      reallocate very large blocks.
 171   malloc_getpagesize        (default: derived from system #includes)
 172      Either a constant or routine call returning the system page size.
 173   HAVE_USR_INCLUDE_MALLOC_H (default: NOT defined)
 174      Optionally define if you are on a system with a /usr/include/malloc.h
 175      that declares struct mallinfo. It is not at all necessary to
 176      define this even if you do, but will ensure consistency.
 177   INTERNAL_SIZE_T           (default: size_t)
 178      Define to a 32-bit type (probably `unsigned int') if you are on a
 179      64-bit machine, yet do not want or need to allow malloc requests of
 180      greater than 2^31 to be handled. This saves space, especially for
 181      very small chunks.
 182   INTERNAL_LINUX_C_LIB      (default: NOT defined)
 183      Defined only when compiled as part of Linux libc.
 184      Also note that there is some odd internal name-mangling via defines
 185      (for example, internally, `malloc' is named `mALLOc') needed
 186      when compiling in this case. These look funny but don't otherwise
 187      affect anything.
 188   WIN32                     (default: undefined)
 189      Define this on MS win (95, nt) platforms to compile in sbrk emulation.
 190   LACKS_UNISTD_H            (default: undefined if not WIN32)
 191      Define this if your system does not have a <unistd.h>.
 192   LACKS_SYS_PARAM_H         (default: undefined if not WIN32)
 193      Define this if your system does not have a <sys/param.h>.
 194   MORECORE                  (default: sbrk)
 195      The name of the routine to call to obtain more memory from the system.
 196   MORECORE_FAILURE          (default: -1)
 197      The value returned upon failure of MORECORE.
 198   MORECORE_CLEARS           (default 1)
 199      True (1) if the routine mapped to MORECORE zeroes out memory (which
 200      holds for sbrk).
 201   DEFAULT_TRIM_THRESHOLD
 202   DEFAULT_TOP_PAD
 203   DEFAULT_MMAP_THRESHOLD
 204   DEFAULT_MMAP_MAX
 205      Default values of tunable parameters (described in detail below)
 206      controlling interaction with host system routines (sbrk, mmap, etc).
 207      These values may also be changed dynamically via mallopt(). The
 208      preset defaults are those that give best performance for typical
 209      programs/systems.
 210   USE_DL_PREFIX             (default: undefined)
 211      Prefix all public routines with the string 'dl'.  Useful to
 212      quickly avoid procedure declaration conflicts and linker symbol
 213      conflicts with existing memory allocation routines.
 214
 215
 216 */
 217
 218 \f
 219 #ifndef __MALLOC_H__
 220 #define __MALLOC_H__
 221
 222 /* Preliminaries */
 223
 224 #ifndef __STD_C
 225 #ifdef __STDC__
 226 #define __STD_C     1
 227 #else
 228 #if __cplusplus
 229 #define __STD_C     1
 230 #else
 231 #define __STD_C     0
 232 #endif /*__cplusplus*/
 233 #endif /*__STDC__*/
 234 #endif /*__STD_C*/
 235
 236 #ifndef Void_t
 237 #if (__STD_C || defined(WIN32))
 238 #define Void_t      void
 239 #else
 240 #define Void_t      char
 241 #endif
 242 #endif /*Void_t*/
 243
 244 #if __STD_C
 245 #include <linux/stddef.h>       /* for size_t */
 246 #else
 247 #include <sys/types.h>
 248 #endif  /* __STD_C */
 249
 250 #ifdef __cplusplus
 251 extern "C" {
 252 #endif
 253
 254 #if 0   /* not for U-Boot */
 255 #include <stdio.h>      /* needed for malloc_stats */
 256 #endif
 257
 258
 259 /*
 260   Compile-time options
 261 */
 262
 263
 264 /*
 265     Debugging:
 266
 267     Because freed chunks may be overwritten with link fields, this
 268     malloc will often die when freed memory is overwritten by user
 269     programs.  This can be very effective (albeit in an annoying way)
 270     in helping track down dangling pointers.
 271
 272     If you compile with -DDEBUG, a number of assertion checks are
 273     enabled that will catch more memory errors. You probably won't be
 274     able to make much sense of the actual assertion errors, but they
 275     should help you locate incorrectly overwritten memory.  The
 276     checking is fairly extensive, and will slow down execution
 277     noticeably. Calling malloc_stats or mallinfo with DEBUG set will
 278     attempt to check every non-mmapped allocated and free chunk in the
 279     course of computing the summmaries. (By nature, mmapped regions
 280     cannot be checked very much automatically.)
 281
 282     Setting DEBUG may also be helpful if you are trying to modify
 283     this code. The assertions in the check routines spell out in more
 284     detail the assumptions and invariants underlying the algorithms.
 285
 286 */
 287
 288 #ifdef DEBUG
 289 /* #include <assert.h> */
 290 #define assert(x) ((void)0)
 291 #else
 292 #define assert(x) ((void)0)
 293 #endif
 294
 295
 296 /*
 297   INTERNAL_SIZE_T is the word-size used for internal bookkeeping
 298   of chunk sizes. On a 64-bit machine, you can reduce malloc
 299   overhead by defining INTERNAL_SIZE_T to be a 32 bit `unsigned int'
 300   at the expense of not being able to handle requests greater than
 301   2^31. This limitation is hardly ever a concern; you are encouraged
 302   to set this. However, the default version is the same as size_t.
 303 */
 304
 305 #ifndef INTERNAL_SIZE_T
 306 #define INTERNAL_SIZE_T size_t
 307 #endif
 308
 309 /*
 310   REALLOC_ZERO_BYTES_FREES should be set if a call to
 311   realloc with zero bytes should be the same as a call to free.
 312   Some people think it should. Otherwise, since this malloc
 313   returns a unique pointer for malloc(0), so does realloc(p, 0).
 314 */
 315
 316
 317 /*   #define REALLOC_ZERO_BYTES_FREES */
 318
 319
 320 /*
 321   WIN32 causes an emulation of sbrk to be compiled in
 322   mmap-based options are not currently supported in WIN32.
 323 */
 324
 325 /* #define WIN32 */
 326 #ifdef WIN32
 327 #define MORECORE wsbrk
 328 #define HAVE_MMAP 0
 329
 330 #define LACKS_UNISTD_H
 331 #define LACKS_SYS_PARAM_H
 332
 333 /*
 334   Include 'windows.h' to get the necessary declarations for the
 335   Microsoft Visual C++ data structures and routines used in the 'sbrk'
 336   emulation.
 337
 338   Define WIN32_LEAN_AND_MEAN so that only the essential Microsoft
 339   Visual C++ header files are included.
 340 */
 341 #define WIN32_LEAN_AND_MEAN
 342 #include <windows.h>
 343 #endif
 344
 345
 346 /*
 347   HAVE_MEMCPY should be defined if you are not otherwise using
 348   ANSI STD C, but still have memcpy and memset in your C library
 349   and want to use them in calloc and realloc. Otherwise simple
 350   macro versions are defined here.
 351
 352   USE_MEMCPY should be defined as 1 if you actually want to
 353   have memset and memcpy called. People report that the macro
 354   versions are often enough faster than libc versions on many
 355   systems that it is better to use them.
 356
 357 */
 358
 359 #define HAVE_MEMCPY
 360
 361 #ifndef USE_MEMCPY
 362 #ifdef HAVE_MEMCPY
 363 #define USE_MEMCPY 1
 364 #else
 365 #define USE_MEMCPY 0
 366 #endif
 367 #endif
 368
 369 #if (__STD_C || defined(HAVE_MEMCPY))
 370
 371 #if __STD_C
 372 void* memset(void*, int, size_t);
 373 void* memcpy(void*, const void*, size_t);
 374 #else
 375 #ifdef WIN32
 376 /* On Win32 platforms, 'memset()' and 'memcpy()' are already declared in */
 377 /* 'windows.h' */
 378 #else
 379 Void_t* memset();
 380 Void_t* memcpy();
 381 #endif
 382 #endif
 383 #endif
 384
 385 #if USE_MEMCPY
 386
 387 /* The following macros are only invoked with (2n+1)-multiples of
 388    INTERNAL_SIZE_T units, with a positive integer n. This is exploited
 389    for fast inline execution when n is small. */
 390
 391 #define MALLOC_ZERO(charp, nbytes)                                            \
 392 do {                                                                          \
 393   INTERNAL_SIZE_T mzsz = (nbytes);                                            \
 394   if(mzsz <= 9*sizeof(mzsz)) {                                                \
 395     INTERNAL_SIZE_T* mz = (INTERNAL_SIZE_T*) (charp);                         \
 396     if(mzsz >= 5*sizeof(mzsz)) {     *mz++ = 0;                               \
 397                                      *mz++ = 0;                               \
 398       if(mzsz >= 7*sizeof(mzsz)) {   *mz++ = 0;                               \
 399                                      *mz++ = 0;                               \
 400         if(mzsz >= 9*sizeof(mzsz)) { *mz++ = 0;                               \
 401                                      *mz++ = 0; }}}                           \
 402                                      *mz++ = 0;                               \
 403                                      *mz++ = 0;                               \
 404                                      *mz   = 0;                               \
 405   } else memset((charp), 0, mzsz);                                            \
 406 } while(0)
 407
 408 #define MALLOC_COPY(dest,src,nbytes)                                          \
 409 do {                                                                          \
 410   INTERNAL_SIZE_T mcsz = (nbytes);                                            \
 411   if(mcsz <= 9*sizeof(mcsz)) {                                                \
 412     INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) (src);                        \
 413     INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) (dest);                       \
 414     if(mcsz >= 5*sizeof(mcsz)) {     *mcdst++ = *mcsrc++;                     \
 415                                      *mcdst++ = *mcsrc++;                     \
 416       if(mcsz >= 7*sizeof(mcsz)) {   *mcdst++ = *mcsrc++;                     \
 417                                      *mcdst++ = *mcsrc++;                     \
 418         if(mcsz >= 9*sizeof(mcsz)) { *mcdst++ = *mcsrc++;                     \
 419                                      *mcdst++ = *mcsrc++; }}}                 \
 420                                      *mcdst++ = *mcsrc++;                     \
 421                                      *mcdst++ = *mcsrc++;                     \
 422                                      *mcdst   = *mcsrc  ;                     \
 423   } else memcpy(dest, src, mcsz);                                             \
 424 } while(0)
 425
 426 #else /* !USE_MEMCPY */
 427
 428 /* Use Duff's device for good zeroing/copying performance. */
 429
 430 #define MALLOC_ZERO(charp, nbytes)                                            \
 431 do {                                                                          \
 432   INTERNAL_SIZE_T* mzp = (INTERNAL_SIZE_T*)(charp);                           \
 433   long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn;                         \
 434   if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; }             \
 435   switch (mctmp) {                                                            \
 436     case 0: for(;;) { *mzp++ = 0;                                             \
 437     case 7:           *mzp++ = 0;                                             \
 438     case 6:           *mzp++ = 0;                                             \
 439     case 5:           *mzp++ = 0;                                             \
 440     case 4:           *mzp++ = 0;                                             \
 441     case 3:           *mzp++ = 0;                                             \
 442     case 2:           *mzp++ = 0;                                             \
 443     case 1:           *mzp++ = 0; if(mcn <= 0) break; mcn--; }                \
 444   }                                                                           \
 445 } while(0)
 446
 447 #define MALLOC_COPY(dest,src,nbytes)                                          \
 448 do {                                                                          \
 449   INTERNAL_SIZE_T* mcsrc = (INTERNAL_SIZE_T*) src;                            \
 450   INTERNAL_SIZE_T* mcdst = (INTERNAL_SIZE_T*) dest;                           \
 451   long mctmp = (nbytes)/sizeof(INTERNAL_SIZE_T), mcn;                         \
 452   if (mctmp < 8) mcn = 0; else { mcn = (mctmp-1)/8; mctmp %= 8; }             \
 453   switch (mctmp) {                                                            \
 454     case 0: for(;;) { *mcdst++ = *mcsrc++;                                    \
 455     case 7:           *mcdst++ = *mcsrc++;                                    \
 456     case 6:           *mcdst++ = *mcsrc++;                                    \
 457     case 5:           *mcdst++ = *mcsrc++;                                    \
 458     case 4:           *mcdst++ = *mcsrc++;                                    \
 459     case 3:           *mcdst++ = *mcsrc++;                                    \
 460     case 2:           *mcdst++ = *mcsrc++;                                    \
 461     case 1:           *mcdst++ = *mcsrc++; if(mcn <= 0) break; mcn--; }       \
 462   }                                                                           \
 463 } while(0)
 464
 465 #endif
 466
 467
 468 /*
 469   Define HAVE_MMAP to optionally make malloc() use mmap() to
 470   allocate very large blocks.  These will be returned to the
 471   operating system immediately after a free().
 472 */
 473
 474 /***
 475 #ifndef HAVE_MMAP
 476 #define HAVE_MMAP 1
 477 #endif
 478 ***/
 479 #undef  HAVE_MMAP       /* Not available for U-Boot */
 480
 481 /*
 482   Define HAVE_MREMAP to make realloc() use mremap() to re-allocate
 483   large blocks.  This is currently only possible on Linux with
 484   kernel versions newer than 1.3.77.
 485 */
 486
 487 /***
 488 #ifndef HAVE_MREMAP
 489 #ifdef INTERNAL_LINUX_C_LIB
 490 #define HAVE_MREMAP 1
 491 #else
 492 #define HAVE_MREMAP 0
 493 #endif
 494 #endif
 495 ***/
 496 #undef  HAVE_MREMAP     /* Not available for U-Boot */
 497
 498 #if HAVE_MMAP
 499
 500 #include <unistd.h>
 501 #include <fcntl.h>
 502 #include <sys/mman.h>
 503
 504 #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
 505 #define MAP_ANONYMOUS MAP_ANON
 506 #endif
 507
 508 #endif /* HAVE_MMAP */
 509
 510 /*
 511   Access to system page size. To the extent possible, this malloc
 512   manages memory from the system in page-size units.
 513
 514   The following mechanics for getpagesize were adapted from
 515   bsd/gnu getpagesize.h
 516 */
 517
 518 #define LACKS_UNISTD_H  /* Shortcut for U-Boot */
 519 #define malloc_getpagesize      4096
 520
 521 #ifndef LACKS_UNISTD_H
 522 #  include <unistd.h>
 523 #endif
 524
 525 #ifndef malloc_getpagesize
 526 #  ifdef _SC_PAGESIZE         /* some SVR4 systems omit an underscore */
 527 #    ifndef _SC_PAGE_SIZE
 528 #      define _SC_PAGE_SIZE _SC_PAGESIZE
 529 #    endif
 530 #  endif
 531 #  ifdef _SC_PAGE_SIZE
 532 #    define malloc_getpagesize sysconf(_SC_PAGE_SIZE)
 533 #  else
 534 #    if defined(BSD) || defined(DGUX) || defined(HAVE_GETPAGESIZE)
 535        extern size_t getpagesize();
 536 #      define malloc_getpagesize getpagesize()
 537 #    else
 538 #      ifdef WIN32
 539 #        define malloc_getpagesize (4096) /* TBD: Use 'GetSystemInfo' instead */
 540 #      else
 541 #        ifndef LACKS_SYS_PARAM_H
 542 #          include <sys/param.h>
 543 #        endif
 544 #        ifdef EXEC_PAGESIZE
 545 #          define malloc_getpagesize EXEC_PAGESIZE
 546 #        else
 547 #          ifdef NBPG
 548 #            ifndef CLSIZE
 549 #              define malloc_getpagesize NBPG
 550 #            else
 551 #              define malloc_getpagesize (NBPG * CLSIZE)
 552 #            endif
 553 #          else
 554 #            ifdef NBPC
 555 #              define malloc_getpagesize NBPC
 556 #            else
 557 #              ifdef PAGESIZE
 558 #                define malloc_getpagesize PAGESIZE
 559 #              else
 560 #                define malloc_getpagesize (4096) /* just guess */
 561 #              endif
 562 #            endif
 563 #          endif
 564 #        endif
 565 #      endif
 566 #    endif
 567 #  endif
 568 #endif
 569
 570
 571 /*
 572
 573   This version of malloc supports the standard SVID/XPG mallinfo
 574   routine that returns a struct containing the same kind of
 575   information you can get from malloc_stats. It should work on
 576   any SVID/XPG compliant system that has a /usr/include/malloc.h
 577   defining struct mallinfo. (If you'd like to install such a thing
 578   yourself, cut out the preliminary declarations as described above
 579   and below and save them in a malloc.h file. But there's no
 580   compelling reason to bother to do this.)
 581
 582   The main declaration needed is the mallinfo struct that is returned
 583   (by-copy) by mallinfo().  The SVID/XPG malloinfo struct contains a
 584   bunch of fields, most of which are not even meaningful in this
 585   version of malloc. Some of these fields are are instead filled by
 586   mallinfo() with other numbers that might possibly be of interest.
 587
 588   HAVE_USR_INCLUDE_MALLOC_H should be set if you have a
 589   /usr/include/malloc.h file that includes a declaration of struct
 590   mallinfo.  If so, it is included; else an SVID2/XPG2 compliant
 591   version is declared below.  These must be precisely the same for
 592   mallinfo() to work.
 593
 594 */
 595
 596 /* #define HAVE_USR_INCLUDE_MALLOC_H */
 597
 598 #if HAVE_USR_INCLUDE_MALLOC_H
 599 #include "/usr/include/malloc.h"
 600 #else
 601
 602 /* SVID2/XPG mallinfo structure */
 603
 604 struct mallinfo {
 605   int arena;    /* total space allocated from system */
 606   int ordblks;  /* number of non-inuse chunks */
 607   int smblks;   /* unused -- always zero */
 608   int hblks;    /* number of mmapped regions */
 609   int hblkhd;   /* total space in mmapped regions */
 610   int usmblks;  /* unused -- always zero */
 611   int fsmblks;  /* unused -- always zero */
 612   int uordblks; /* total allocated space */
 613   int fordblks; /* total non-inuse space */
 614   int keepcost; /* top-most, releasable (via malloc_trim) space */
 615 };
 616
 617 /* SVID2/XPG mallopt options */
 618
 619 #define M_MXFAST  1    /* UNUSED in this malloc */
 620 #define M_NLBLKS  2    /* UNUSED in this malloc */
 621 #define M_GRAIN   3    /* UNUSED in this malloc */
 622 #define M_KEEP    4    /* UNUSED in this malloc */
 623
 624 #endif
 625
 626 /* mallopt options that actually do something */
 627
 628 #define M_TRIM_THRESHOLD    -1
 629 #define M_TOP_PAD           -2
 630 #define M_MMAP_THRESHOLD    -3
 631 #define M_MMAP_MAX          -4
 632
 633
 634 #ifndef DEFAULT_TRIM_THRESHOLD
 635 #define DEFAULT_TRIM_THRESHOLD (128 * 1024)
 636 #endif
 637
 638 /*
 639     M_TRIM_THRESHOLD is the maximum amount of unused top-most memory
 640       to keep before releasing via malloc_trim in free().
 641
 642       Automatic trimming is mainly useful in long-lived programs.
 643       Because trimming via sbrk can be slow on some systems, and can
 644       sometimes be wasteful (in cases where programs immediately
 645       afterward allocate more large chunks) the value should be high
 646       enough so that your overall system performance would improve by
 647       releasing.
 648
 649       The trim threshold and the mmap control parameters (see below)
 650       can be traded off with one another. Trimming and mmapping are
 651       two different ways of releasing unused memory back to the
 652       system. Between these two, it is often possible to keep
 653       system-level demands of a long-lived program down to a bare
 654       minimum. For example, in one test suite of sessions measuring
 655       the XF86 X server on Linux, using a trim threshold of 128K and a
 656       mmap threshold of 192K led to near-minimal long term resource
 657       consumption.
 658
 659       If you are using this malloc in a long-lived program, it should
 660       pay to experiment with these values.  As a rough guide, you
 661       might set to a value close to the average size of a process
 662       (program) running on your system.  Releasing this much memory
 663       would allow such a process to run in memory.  Generally, it's
 664       worth it to tune for trimming rather tham memory mapping when a
 665       program undergoes phases where several large chunks are
 666       allocated and released in ways that can reuse each other's
 667       storage, perhaps mixed with phases where there are no such
 668       chunks at all.  And in well-behaved long-lived programs,
 669       controlling release of large blocks via trimming versus mapping
 670       is usually faster.
 671
 672       However, in most programs, these parameters serve mainly as
 673       protection against the system-level effects of carrying around
 674       massive amounts of unneeded memory. Since frequent calls to
 675       sbrk, mmap, and munmap otherwise degrade performance, the default
 676       parameters are set to relatively high values that serve only as
 677       safeguards.
 678
 679       The default trim value is high enough to cause trimming only in
 680       fairly extreme (by current memory consumption standards) cases.
 681       It must be greater than page size to have any useful effect.  To
 682       disable trimming completely, you can set to (unsigned long)(-1);
 683
 684
 685 */
 686
 687
 688 #ifndef DEFAULT_TOP_PAD
 689 #define DEFAULT_TOP_PAD        (0)
 690 #endif
 691
 692 /*
 693     M_TOP_PAD is the amount of extra `padding' space to allocate or
 694       retain whenever sbrk is called. It is used in two ways internally:
 695
 696       * When sbrk is called to extend the top of the arena to satisfy
 697         a new malloc request, this much padding is added to the sbrk
 698         request.
 699
 700       * When malloc_trim is called automatically from free(),
 701         it is used as the `pad' argument.
 702
 703       In both cases, the actual amount of padding is rounded
 704       so that the end of the arena is always a system page boundary.
 705
 706       The main reason for using padding is to avoid calling sbrk so
 707       often. Having even a small pad greatly reduces the likelihood
 708       that nearly every malloc request during program start-up (or
 709       after trimming) will invoke sbrk, which needlessly wastes
 710       time.
 711
 712       Automatic rounding-up to page-size units is normally sufficient
 713       to avoid measurable overhead, so the default is 0.  However, in
 714       systems where sbrk is relatively slow, it can pay to increase
 715       this value, at the expense of carrying around more memory than
 716       the program needs.
 717
 718 */
 719
 720
 721 #ifndef DEFAULT_MMAP_THRESHOLD
 722 #define DEFAULT_MMAP_THRESHOLD (128 * 1024)
 723 #endif
 724
 725 /*
 726
 727     M_MMAP_THRESHOLD is the request size threshold for using mmap()
 728       to service a request. Requests of at least this size that cannot
 729       be allocated using already-existing space will be serviced via mmap.
 730       (If enough normal freed space already exists it is used instead.)
 731
 732       Using mmap segregates relatively large chunks of memory so that
 733       they can be individually obtained and released from the host
 734       system. A request serviced through mmap is never reused by any
 735       other request (at least not directly; the system may just so
 736       happen to remap successive requests to the same locations).
 737
 738       Segregating space in this way has the benefit that mmapped space
 739       can ALWAYS be individually released back to the system, which
 740       helps keep the system level memory demands of a long-lived
 741       program low. Mapped memory can never become `locked' between
 742       other chunks, as can happen with normally allocated chunks, which
 743       menas that even trimming via malloc_trim would not release them.
 744
 745       However, it has the disadvantages that:
 746
 747          1. The space cannot be reclaimed, consolidated, and then
 748             used to service later requests, as happens with normal chunks.
 749          2. It can lead to more wastage because of mmap page alignment
 750             requirements
 751          3. It causes malloc performance to be more dependent on host
 752             system memory management support routines which may vary in
 753             implementation quality and may impose arbitrary
 754             limitations. Generally, servicing a request via normal
 755             malloc steps is faster than going through a system's mmap.
 756
 757       All together, these considerations should lead you to use mmap
 758       only for relatively large requests.
 759
 760
 761 */
 762
 763
 764 #ifndef DEFAULT_MMAP_MAX
 765 #if HAVE_MMAP
 766 #define DEFAULT_MMAP_MAX       (64)
 767 #else
 768 #define DEFAULT_MMAP_MAX       (0)
 769 #endif
 770 #endif
 771
 772 /*
 773     M_MMAP_MAX is the maximum number of requests to simultaneously
 774       service using mmap. This parameter exists because:
 775
 776          1. Some systems have a limited number of internal tables for
 777             use by mmap.
 778          2. In most systems, overreliance on mmap can degrade overall
 779             performance.
 780          3. If a program allocates many large regions, it is probably
 781             better off using normal sbrk-based allocation routines that
 782             can reclaim and reallocate normal heap memory. Using a
 783             small value allows transition into this mode after the
 784             first few allocations.
 785
 786       Setting to 0 disables all use of mmap.  If HAVE_MMAP is not set,
 787       the default value is 0, and attempts to set it to non-zero values
 788       in mallopt will fail.
 789 */
 790
 791
 792 /*
 793     USE_DL_PREFIX will prefix all public routines with the string 'dl'.
 794       Useful to quickly avoid procedure declaration conflicts and linker
 795       symbol conflicts with existing memory allocation routines.
 796
 797 */
 798
 799 /* #define USE_DL_PREFIX */
 800
 801
 802 /*
 803
 804   Special defines for linux libc
 805
 806   Except when compiled using these special defines for Linux libc
 807   using weak aliases, this malloc is NOT designed to work in
 808   multithreaded applications.  No semaphores or other concurrency
 809   control are provided to ensure that multiple malloc or free calls
 810   don't run at the same time, which could be disasterous. A single
 811   semaphore could be used across malloc, realloc, and free (which is
 812   essentially the effect of the linux weak alias approach). It would
 813   be hard to obtain finer granularity.
 814
 815 */
 816
 817
 818 #ifdef INTERNAL_LINUX_C_LIB
 819
 820 #if __STD_C
 821
 822 Void_t * __default_morecore_init (ptrdiff_t);
 823 Void_t *(*__morecore)(ptrdiff_t) = __default_morecore_init;
 824
 825 #else
 826
 827 Void_t * __default_morecore_init ();
 828 Void_t *(*__morecore)() = __default_morecore_init;
 829
 830 #endif
 831
 832 #define MORECORE (*__morecore)
 833 #define MORECORE_FAILURE 0
 834 #define MORECORE_CLEARS 1
 835
 836 #else /* INTERNAL_LINUX_C_LIB */
 837
 838 #if __STD_C
 839 extern Void_t*     sbrk(ptrdiff_t);
 840 #else
 841 extern Void_t*     sbrk();
 842 #endif
 843
 844 #ifndef MORECORE
 845 #define MORECORE sbrk
 846 #endif
 847
 848 #ifndef MORECORE_FAILURE
 849 #define MORECORE_FAILURE -1
 850 #endif
 851
 852 #ifndef MORECORE_CLEARS
 853 #define MORECORE_CLEARS 1
 854 #endif
 855
 856 #endif /* INTERNAL_LINUX_C_LIB */
 857
 858 #if defined(INTERNAL_LINUX_C_LIB) && defined(__ELF__)
 859
 860 #define cALLOc          __libc_calloc
 861 #define fREe            __libc_free
 862 #define mALLOc          __libc_malloc
 863 #define mEMALIGn        __libc_memalign
 864 #define rEALLOc         __libc_realloc
 865 #define vALLOc          __libc_valloc
 866 #define pvALLOc         __libc_pvalloc
 867 #define mALLINFo        __libc_mallinfo
 868 #define mALLOPt         __libc_mallopt
 869
 870 #pragma weak calloc = __libc_calloc
 871 #pragma weak free = __libc_free
 872 #pragma weak cfree = __libc_free
 873 #pragma weak malloc = __libc_malloc
 874 #pragma weak memalign = __libc_memalign
 875 #pragma weak realloc = __libc_realloc
 876 #pragma weak valloc = __libc_valloc
 877 #pragma weak pvalloc = __libc_pvalloc
 878 #pragma weak mallinfo = __libc_mallinfo
 879 #pragma weak mallopt = __libc_mallopt
 880
 881 #else
 882
 883 #ifdef USE_DL_PREFIX
 884 #define cALLOc          dlcalloc
 885 #define fREe            dlfree
 886 #define mALLOc          dlmalloc
 887 #define mEMALIGn        dlmemalign
 888 #define rEALLOc         dlrealloc
 889 #define vALLOc          dlvalloc
 890 #define pvALLOc         dlpvalloc
 891 #define mALLINFo        dlmallinfo
 892 #define mALLOPt         dlmallopt
 893 #else /* USE_DL_PREFIX */
 894 #define cALLOc          calloc
 895 #define fREe            free
 896 #define mALLOc          malloc
 897 #define mEMALIGn        memalign
 898 #define rEALLOc         realloc
 899 #define vALLOc          valloc
 900 #define pvALLOc         pvalloc
 901 #define mALLINFo        mallinfo
 902 #define mALLOPt         mallopt
 903 #endif /* USE_DL_PREFIX */
 904
 905 #endif
 906
 907 /* Public routines */
 908
 909 #if __STD_C
 910
 911 Void_t* mALLOc(size_t);
 912 void    fREe(Void_t*);
 913 Void_t* rEALLOc(Void_t*, size_t);
 914 Void_t* mEMALIGn(size_t, size_t);
 915 Void_t* vALLOc(size_t);
 916 Void_t* pvALLOc(size_t);
 917 Void_t* cALLOc(size_t, size_t);
 918 void    cfree(Void_t*);
 919 int     malloc_trim(size_t);
 920 size_t  malloc_usable_size(Void_t*);
 921 void    malloc_stats(void);
 922 int     mALLOPt(int, int);
 923 struct mallinfo mALLINFo(void);
 924 #else
 925 Void_t* mALLOc();
 926 void    fREe();
 927 Void_t* rEALLOc();
 928 Void_t* mEMALIGn();
 929 Void_t* vALLOc();
 930 Void_t* pvALLOc();
 931 Void_t* cALLOc();
 932 void    cfree();
 933 int     malloc_trim();
 934 size_t  malloc_usable_size();
 935 void    malloc_stats();
 936 int     mALLOPt();
 937 struct mallinfo mALLINFo();
 938 #endif
 939
 940 /*
 941  * Begin and End of memory area for malloc(), and current "brk"
 942  */
 943 extern ulong mem_malloc_start;
 944 extern ulong mem_malloc_end;
 945 extern ulong mem_malloc_brk;
 946
 947 void mem_malloc_init(ulong start, ulong size);
 948
 949 #ifdef __cplusplus
 950 };  /* end of extern "C" */
 951 #endif
 952
 953 #endif /* __MALLOC_H__ */