mmalloc/mmalloc.h

   1 /* Declarations for `mmalloc' and friends.
   2    Copyright 1990, 1991, 1992 Free Software Foundation
   3
   4    Written May 1989 by Mike Haertel.
   5    Heavily modified Mar 1992 by Fred Fish. (fnf@cygnus.com)
   6
   7 The GNU C Library is free software; you can redistribute it and/or
   8 modify it under the terms of the GNU Library General Public License as
   9 published by the Free Software Foundation; either version 2 of the
  10 License, or (at your option) any later version.
  11
  12 The GNU C Library is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 Library General Public License for more details.
  16
  17 You should have received a copy of the GNU Library General Public
  18 License along with the GNU C Library; see the file COPYING.LIB.  If
  19 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  20 Cambridge, MA 02139, USA.
  21
  22    The author may be reached (Email) at the address mike@ai.mit.edu,
  23    or (US mail) as Mike Haertel c/o Free Software Foundation. */
  24
  25
  26 #ifndef __MMALLOC_H
  27 #define __MMALLOC_H 1
  28
  29 /* Ugly kludge to work around problem with some vendors (Sun for example)
  30    that ship the ANSI <stdlib.h> file with non-ANSI compliant declarations
  31    for malloc(), realloc(), calloc(), and free().  Since we don't use
  32    these functions internally, but simply provide compatible replacements
  33    layered on top of the m* equivalents, just hide whatever definitions
  34    <stdlib.h> might supply. */
  35
  36 #define malloc hide_malloc
  37 #define calloc hide_calloc
  38 #define realloc hide_realloc
  39 #define free hide_free
  40
  41 #ifdef  __STDC__
  42 #  include <stddef.h>
  43 #  include <stdlib.h>
  44 #  define PTR void *
  45 #  define CONST const
  46 #  define PARAMS(paramlist) paramlist
  47 #  include <limits.h>
  48 #  ifndef NULL
  49 #    define NULL (void *) 0
  50 #  endif
  51 #else
  52 #  undef size_t
  53 #  define size_t unsigned int
  54 #  define CHAR_BIT 8
  55 #  define PTR char *
  56 #  define CONST /* nothing */
  57 #  define PARAMS(paramlist) ()
  58 #  ifndef NULL
  59 #    define NULL 0
  60 #  endif
  61 #endif
  62
  63 #undef malloc   /* Undo the kludge to hide non-ANSI compliant declarations */
  64 #undef calloc
  65 #undef realloc
  66 #undef free
  67
  68 #if defined(USG)
  69 #  include <string.h>
  70 #endif
  71
  72 #ifndef MIN
  73 #  define MIN(A, B) ((A) < (B) ? (A) : (B))
  74 #endif
  75
  76 #define MMALLOC_MAGIC           "mmalloc"       /* Mapped file magic number */
  77 #define MMALLOC_MAGIC_SIZE      8               /* Size of magic number buf */
  78 #define MMALLOC_VERSION         1               /* Current mmalloc version */
  79 #define MMALLOC_KEYS            16              /* Keys for application use */
  80
  81 /* The allocator divides the heap into blocks of fixed size; large
  82    requests receive one or more whole blocks, and small requests
  83    receive a fragment of a block.  Fragment sizes are powers of two,
  84    and all fragments of a block are the same size.  When all the
  85    fragments in a block have been freed, the block itself is freed.  */
  86
  87 #define INT_BIT         (CHAR_BIT * sizeof(int))
  88 #define BLOCKLOG        (INT_BIT > 16 ? 12 : 9)
  89 #define BLOCKSIZE       ((unsigned int) 1 << BLOCKLOG)
  90 #define BLOCKIFY(SIZE)  (((SIZE) + BLOCKSIZE - 1) / BLOCKSIZE)
  91
  92 /* The difference between two pointers is a signed int.  On machines where
  93    the data addresses have the high bit set, we need to ensure that the
  94    difference becomes an unsigned int when we are using the address as an
  95    integral value.  In addition, when using with the '%' operator, the
  96    sign of the result is machine dependent for negative values, so force
  97    it to be treated as an unsigned int. */
  98
  99 #define ADDR2UINT(addr) ((unsigned int) ((char *) (addr) - (char *) NULL))
 100 #define RESIDUAL(addr,bsize) ((unsigned int) (ADDR2UINT (addr) % (bsize)))
 101
 102 /* Determine the amount of memory spanned by the initial heap table
 103    (not an absolute limit).  */
 104
 105 #define HEAP            (INT_BIT > 16 ? 4194304 : 65536)
 106
 107 /* Number of contiguous free blocks allowed to build up at the end of
 108    memory before they will be returned to the system.  */
 109
 110 #define FINAL_FREE_BLOCKS       8
 111
 112 /* Where to start searching the free list when looking for new memory.
 113    The two possible values are 0 and heapindex.  Starting at 0 seems
 114    to reduce total memory usage, while starting at heapindex seems to
 115    run faster.  */
 116
 117 #define MALLOC_SEARCH_START     mdp -> heapindex
 118
 119 /* Address to block number and vice versa.  */
 120
 121 #define BLOCK(A) (((char *) (A) - mdp -> heapbase) / BLOCKSIZE + 1)
 122
 123 #define ADDRESS(B) ((PTR) (((B) - 1) * BLOCKSIZE + mdp -> heapbase))
 124
 125 /* Data structure giving per-block information.  */
 126
 127 typedef union
 128   {
 129     /* Heap information for a busy block.  */
 130     struct
 131       {
 132         /* Zero for a large block, or positive giving the
 133            logarithm to the base two of the fragment size.  */
 134         int type;
 135         union
 136           {
 137             struct
 138               {
 139                 size_t nfree;   /* Free fragments in a fragmented block.  */
 140                 size_t first;   /* First free fragment of the block.  */
 141               } frag;
 142             /* Size (in blocks) of a large cluster.  */
 143             size_t size;
 144           } info;
 145       } busy;
 146     /* Heap information for a free block (that may be the first of
 147        a free cluster).  */
 148     struct
 149       {
 150         size_t size;            /* Size (in blocks) of a free cluster.  */
 151         size_t next;            /* Index of next free cluster.  */
 152         size_t prev;            /* Index of previous free cluster.  */
 153       } free;
 154   } malloc_info;
 155
 156 /* List of blocks allocated with `mmemalign' (or `mvalloc').  */
 157
 158 struct alignlist
 159   {
 160     struct alignlist *next;
 161     PTR aligned;                /* The address that mmemaligned returned.  */
 162     PTR exact;                  /* The address that malloc returned.  */
 163   };
 164
 165 /* Doubly linked lists of free fragments.  */
 166
 167 struct list
 168   {
 169     struct list *next;
 170     struct list *prev;
 171   };
 172
 173 /* Statistics available to the user.
 174    FIXME:  By design, the internals of the malloc package are no longer
 175    exported to the user via an include file, so access to this data needs
 176    to be via some other mechanism, such as mmstat_<something> where the
 177    return value is the <something> the user is interested in. */
 178
 179 struct mstats
 180   {
 181     size_t bytes_total;         /* Total size of the heap. */
 182     size_t chunks_used;         /* Chunks allocated by the user. */
 183     size_t bytes_used;          /* Byte total of user-allocated chunks. */
 184     size_t chunks_free;         /* Chunks in the free list. */
 185     size_t bytes_free;          /* Byte total of chunks in the free list. */
 186   };
 187
 188 /* Internal structure that defines the format of the malloc-descriptor.
 189    This gets written to the base address of the region that mmalloc is
 190    managing, and thus also becomes the file header for the mapped file,
 191    if such a file exists. */
 192
 193 struct mdesc
 194 {
 195   /* The "magic number" for an mmalloc file. */
 196
 197   char magic[MMALLOC_MAGIC_SIZE];
 198
 199   /* The size in bytes of this structure, used as a sanity check when reusing
 200      a previously created mapped file. */
 201
 202   unsigned int headersize;
 203
 204   /* The version number of the mmalloc package that created this file. */
 205
 206   unsigned char version;
 207
 208   /* Some flag bits to keep track of various internal things. */
 209
 210   unsigned int flags;
 211
 212   /* If a system call made by the mmalloc package fails, the errno is
 213      preserved for future examination. */
 214
 215   int errno;
 216
 217   /* Pointer to the function that is used to get more core, or return core
 218      to the system, for requests using this malloc descriptor.  For memory
 219      mapped regions, this is the mmap() based routine.  There may also be
 220      a single malloc descriptor that points to an sbrk() based routine
 221      for systems without mmap() or for applications that call the mmalloc()
 222      package with a NULL malloc descriptor. */
 223
 224   PTR (*morecore) PARAMS ((struct mdesc *, ptrdiff_t));
 225
 226   /* Pointer to the function that causes an abort when the memory checking
 227      features are activated.  By default this is set to abort(), but can
 228      be set to another function by the application using mmalloc(). */
 229
 230   void (*abortfunc) PARAMS ((void));
 231
 232   /* Debugging hook for free.  */
 233
 234   void (*mfree_hook) PARAMS ((PTR, PTR));
 235
 236   /* Debugging hook for `malloc'.  */
 237
 238   PTR (*mmalloc_hook) PARAMS ((PTR, size_t));
 239
 240   /* Debugging hook for realloc.  */
 241
 242   PTR (*mrealloc_hook) PARAMS ((PTR, PTR, size_t));
 243
 244   /* Number of info entries.  */
 245
 246   size_t heapsize;
 247
 248   /* Pointer to first block of the heap (base of the first block).  */
 249
 250   char *heapbase;
 251
 252   /* Current search index for the heap table.  */
 253   /* Search index in the info table.  */
 254
 255   size_t heapindex;
 256
 257   /* Limit of valid info table indices.  */
 258
 259   size_t heaplimit;
 260
 261   /* Block information table.
 262      Allocated with malign/__mmalloc_free (not mmalloc/mfree).  */
 263   /* Table indexed by block number giving per-block information.  */
 264
 265   malloc_info *heapinfo;
 266
 267   /* Instrumentation.  */
 268
 269   struct mstats heapstats;
 270
 271   /* Free list headers for each fragment size.  */
 272   /* Free lists for each fragment size.  */
 273
 274   struct list fraghead[BLOCKLOG];
 275
 276   /* List of blocks allocated by memalign.  */
 277
 278   struct alignlist *aligned_blocks;
 279
 280   /* The base address of the memory region for this malloc heap.  This
 281      is the location where the bookkeeping data for mmap and for malloc
 282      begins. */
 283
 284   char *base;
 285
 286   /* The current location in the memory region for this malloc heap which
 287      represents the end of memory in use. */
 288
 289   char *breakval;
 290
 291   /* The end of the current memory region for this malloc heap.  This is
 292      the first location past the end of mapped memory. */
 293
 294   char *top;
 295
 296   /* Open file descriptor for the file to which this malloc heap is mapped.
 297      This will always be a valid file descriptor, since /dev/zero is used
 298      by default if no open file is supplied by the client.  Also note that
 299      it may change each time the region is mapped and unmapped. */
 300
 301   int fd;
 302
 303   /* An array of keys to data within the mapped region, for use by the
 304      application.  */
 305
 306   void *keys[MMALLOC_KEYS];
 307
 308 };
 309
 310 /* Bits to look at in the malloc descriptor flags word */
 311
 312 #define MMALLOC_DEVZERO         (1 << 0)        /* Have mapped to /dev/zero */
 313 #define MMALLOC_INITIALIZED     (1 << 1)        /* Initialized mmalloc */
 314 #define MMALLOC_MMCHECK_USED    (1 << 2)        /* mmcheck() called already */
 315
 316 /* Allocate SIZE bytes of memory.  */
 317
 318 extern PTR mmalloc PARAMS ((PTR, size_t));
 319
 320 /* Re-allocate the previously allocated block in PTR, making the new block
 321    SIZE bytes long.  */
 322
 323 extern PTR mrealloc PARAMS ((PTR, PTR, size_t));
 324
 325 /* Allocate NMEMB elements of SIZE bytes each, all initialized to 0.  */
 326
 327 extern PTR mcalloc PARAMS ((PTR, size_t, size_t));
 328
 329 /* Free a block allocated by `mmalloc', `mrealloc' or `mcalloc'.  */
 330
 331 extern void mfree PARAMS ((PTR, PTR));
 332
 333 /* Allocate SIZE bytes allocated to ALIGNMENT bytes.  */
 334
 335 extern PTR mmemalign PARAMS ((PTR, size_t, size_t));
 336
 337 /* Allocate SIZE bytes on a page boundary.  */
 338
 339 extern PTR mvalloc PARAMS ((PTR, size_t));
 340
 341 /* Activate a standard collection of debugging hooks.  */
 342
 343 extern int mmcheck PARAMS ((PTR, void (*) (void)));
 344
 345 /* Pick up the current statistics. (see FIXME elsewhere) */
 346
 347 extern struct mstats mmstats PARAMS ((PTR));
 348
 349 /* Internal version of `mfree' used in `morecore'. */
 350
 351 extern void __mmalloc_free PARAMS ((struct mdesc *, PTR));
 352
 353 /* Hooks for debugging versions.  */
 354
 355 extern void (*__mfree_hook) PARAMS ((PTR, PTR));
 356 extern PTR (*__mmalloc_hook) PARAMS ((PTR, size_t));
 357 extern PTR (*__mrealloc_hook) PARAMS ((PTR, PTR, size_t));
 358
 359 /* A default malloc descriptor for the single sbrk() managed region. */
 360
 361 extern struct mdesc *__mmalloc_default_mdp;
 362
 363 /* Initialize the first use of the default malloc descriptor, which uses
 364    an sbrk() region. */
 365
 366 extern struct mdesc *__mmalloc_sbrk_init PARAMS ((void));
 367
 368 /* Grow or shrink a contiguous region using sbrk(). */
 369
 370 extern PTR __mmalloc_sbrk_morecore PARAMS ((struct mdesc *, int));
 371
 372 /* Grow or shrink a contiguous mapped region using mmap().
 373    Works much like sbrk() */
 374
 375 #if defined(HAVE_MMAP)
 376
 377 extern PTR __mmalloc_mmap_morecore PARAMS ((struct mdesc *, int));
 378
 379 #endif
 380
 381 /* Remap a mmalloc region that was previously mapped. */
 382
 383 extern PTR __mmalloc_remap_core PARAMS ((struct mdesc *));
 384
 385 /* Macro to convert from a user supplied malloc descriptor to pointer to the
 386    internal malloc descriptor.  If the user supplied descriptor is NULL, then
 387    use the default internal version, initializing it if necessary.  Otherwise
 388    just cast the user supplied version (which is void *) to the proper type
 389    (struct mdesc *). */
 390
 391 #define MD_TO_MDP(md) \
 392   ((md) == NULL \
 393    ? (__mmalloc_default_mdp == NULL \
 394       ? __mmalloc_sbrk_init () \
 395       : __mmalloc_default_mdp) \
 396    : (struct mdesc *) (md))
 397
 398 #endif  /* __MMALLOC_H */