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