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