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