mmalloc/mmprivate.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., 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, 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 __MMPRIVATE_H
  27 #define __MMPRIVATE_H 1
  28
  29 #include "mmalloc.h"
  30
  31 #ifdef  STDC_HEADERS
  32 #  include <limits.h>
  33 #  ifndef NULL
  34 #    define NULL (void *) 0
  35 #  endif
  36 #else
  37 #  ifndef size_t
  38 #    define size_t unsigned int
  39 #  endif
  40 #  ifndef CHAR_BIT
  41 #    define CHAR_BIT 8
  42 #  endif
  43 #  ifndef NULL
  44 #    define NULL 0
  45 #  endif
  46 #endif
  47
  48 #ifndef MIN
  49 #  define MIN(A, B) ((A) < (B) ? (A) : (B))
  50 #endif
  51
  52 #define MMALLOC_MAGIC           "mmalloc"       /* Mapped file magic number */
  53 #define MMALLOC_MAGIC_SIZE      8               /* Size of magic number buf */
  54 #define MMALLOC_VERSION         1               /* Current mmalloc version */
  55 #define MMALLOC_KEYS            16              /* Keys for application use */
  56
  57 /* The allocator divides the heap into blocks of fixed size; large
  58    requests receive one or more whole blocks, and small requests
  59    receive a fragment of a block.  Fragment sizes are powers of two,
  60    and all fragments of a block are the same size.  When all the
  61    fragments in a block have been freed, the block itself is freed.  */
  62
  63 #define INT_BIT         (CHAR_BIT * sizeof(int))
  64 #define BLOCKLOG        (INT_BIT > 16 ? 12 : 9)
  65 #define BLOCKSIZE       ((unsigned int) 1 << BLOCKLOG)
  66 #define BLOCKIFY(SIZE)  (((SIZE) + BLOCKSIZE - 1) / BLOCKSIZE)
  67
  68 /* The difference between two pointers is a signed int.  On machines where
  69    the data addresses have the high bit set, we need to ensure that the
  70    difference becomes an unsigned int when we are using the address as an
  71    integral value.  In addition, when using with the '%' operator, the
  72    sign of the result is machine dependent for negative values, so force
  73    it to be treated as an unsigned int. */
  74
  75 #define ADDR2UINT(addr) ((unsigned int) ((char *) (addr) - (char *) NULL))
  76 #define RESIDUAL(addr,bsize) ((unsigned int) (ADDR2UINT (addr) % (bsize)))
  77
  78 /* Determine the amount of memory spanned by the initial heap table
  79    (not an absolute limit).  */
  80
  81 #define HEAP            (INT_BIT > 16 ? 4194304 : 65536)
  82
  83 /* Number of contiguous free blocks allowed to build up at the end of
  84    memory before they will be returned to the system.  */
  85
  86 #define FINAL_FREE_BLOCKS       8
  87
  88 /* Where to start searching the free list when looking for new memory.
  89    The two possible values are 0 and heapindex.  Starting at 0 seems
  90    to reduce total memory usage, while starting at heapindex seems to
  91    run faster.  */
  92
  93 #define MALLOC_SEARCH_START     mdp -> heapindex
  94
  95 /* Address to block number and vice versa.  */
  96
  97 #define BLOCK(A) (((char *) (A) - mdp -> heapbase) / BLOCKSIZE + 1)
  98
  99 #define ADDRESS(B) ((PTR) (((B) - 1) * BLOCKSIZE + mdp -> heapbase))
 100
 101 /* Data structure giving per-block information.  */
 102
 103 typedef union
 104   {
 105     /* Heap information for a busy block.  */
 106     struct
 107       {
 108         /* Zero for a large block, or positive giving the
 109            logarithm to the base two of the fragment size.  */
 110         int type;
 111         union
 112           {
 113             struct
 114               {
 115                 size_t nfree;   /* Free fragments in a fragmented block.  */
 116                 size_t first;   /* First free fragment of the block.  */
 117               } frag;
 118             /* Size (in blocks) of a large cluster.  */
 119             size_t size;
 120           } info;
 121       } busy;
 122     /* Heap information for a free block (that may be the first of
 123        a free cluster).  */
 124     struct
 125       {
 126         size_t size;            /* Size (in blocks) of a free cluster.  */
 127         size_t next;            /* Index of next free cluster.  */
 128         size_t prev;            /* Index of previous free cluster.  */
 129       } free;
 130   } malloc_info;
 131
 132 /* List of blocks allocated with `mmemalign' (or `mvalloc').  */
 133
 134 struct alignlist
 135   {
 136     struct alignlist *next;
 137     PTR aligned;                /* The address that mmemaligned returned.  */
 138     PTR exact;                  /* The address that malloc returned.  */
 139   };
 140
 141 /* Doubly linked lists of free fragments.  */
 142
 143 struct list
 144   {
 145     struct list *next;
 146     struct list *prev;
 147   };
 148
 149 /* Statistics available to the user.
 150    FIXME:  By design, the internals of the malloc package are no longer
 151    exported to the user via an include file, so access to this data needs
 152    to be via some other mechanism, such as mmstat_<something> where the
 153    return value is the <something> the user is interested in. */
 154
 155 struct mstats
 156   {
 157     size_t bytes_total;         /* Total size of the heap. */
 158     size_t chunks_used;         /* Chunks allocated by the user. */
 159     size_t bytes_used;          /* Byte total of user-allocated chunks. */
 160     size_t chunks_free;         /* Chunks in the free list. */
 161     size_t bytes_free;          /* Byte total of chunks in the free list. */
 162   };
 163
 164 /* Internal structure that defines the format of the malloc-descriptor.
 165    This gets written to the base address of the region that mmalloc is
 166    managing, and thus also becomes the file header for the mapped file,
 167    if such a file exists. */
 168
 169 struct mdesc
 170 {
 171   /* The "magic number" for an mmalloc file. */
 172
 173   char magic[MMALLOC_MAGIC_SIZE];
 174
 175   /* The size in bytes of this structure, used as a sanity check when reusing
 176      a previously created mapped file. */
 177
 178   unsigned int headersize;
 179
 180   /* The version number of the mmalloc package that created this file. */
 181
 182   unsigned char version;
 183
 184   /* Some flag bits to keep track of various internal things. */
 185
 186   unsigned int flags;
 187
 188   /* If a system call made by the mmalloc package fails, the errno is
 189      preserved for future examination. */
 190
 191   int saved_errno;
 192
 193   /* Pointer to the function that is used to get more core, or return core
 194      to the system, for requests using this malloc descriptor.  For memory
 195      mapped regions, this is the mmap() based routine.  There may also be
 196      a single malloc descriptor that points to an sbrk() based routine
 197      for systems without mmap() or for applications that call the mmalloc()
 198      package with a NULL malloc descriptor.
 199
 200      FIXME:  For mapped regions shared by more than one process, this
 201      needs to be maintained on a per-process basis. */
 202
 203   PTR (*morecore) PARAMS ((struct mdesc *, int));
 204
 205   /* Pointer to the function that causes an abort when the memory checking
 206      features are activated.  By default this is set to abort(), but can
 207      be set to another function by the application using mmalloc().
 208
 209      FIXME:  For mapped regions shared by more than one process, this
 210      needs to be maintained on a per-process basis. */
 211
 212   void (*abortfunc) PARAMS ((void));
 213
 214   /* Debugging hook for free.
 215
 216      FIXME:  For mapped regions shared by more than one process, this
 217      needs to be maintained on a per-process basis. */
 218
 219   void (*mfree_hook) PARAMS ((PTR, PTR));
 220
 221   /* Debugging hook for `malloc'.
 222
 223      FIXME:  For mapped regions shared by more than one process, this
 224      needs to be maintained on a per-process basis. */
 225
 226   PTR (*mmalloc_hook) PARAMS ((PTR, size_t));
 227
 228   /* Debugging hook for realloc.
 229
 230      FIXME:  For mapped regions shared by more than one process, this
 231      needs to be maintained on a per-process basis. */
 232
 233   PTR (*mrealloc_hook) PARAMS ((PTR, PTR, size_t));
 234
 235   /* Number of info entries.  */
 236
 237   size_t heapsize;
 238
 239   /* Pointer to first block of the heap (base of the first block).  */
 240
 241   char *heapbase;
 242
 243   /* Current search index for the heap table.  */
 244   /* Search index in the info table.  */
 245
 246   size_t heapindex;
 247
 248   /* Limit of valid info table indices.  */
 249
 250   size_t heaplimit;
 251
 252   /* Block information table.
 253      Allocated with malign/__mmalloc_free (not mmalloc/mfree).  */
 254   /* Table indexed by block number giving per-block information.  */
 255
 256   malloc_info *heapinfo;
 257
 258   /* Instrumentation.  */
 259
 260   struct mstats heapstats;
 261
 262   /* Free list headers for each fragment size.  */
 263   /* Free lists for each fragment size.  */
 264
 265   struct list fraghead[BLOCKLOG];
 266
 267   /* List of blocks allocated by memalign.  */
 268
 269   struct alignlist *aligned_blocks;
 270
 271   /* The base address of the memory region for this malloc heap.  This
 272      is the location where the bookkeeping data for mmap and for malloc
 273      begins. */
 274
 275   char *base;
 276
 277   /* The current location in the memory region for this malloc heap which
 278      represents the end of memory in use. */
 279
 280   char *breakval;
 281
 282   /* The end of the current memory region for this malloc heap.  This is
 283      the first location past the end of mapped memory. */
 284
 285   char *top;
 286
 287   /* Open file descriptor for the file to which this malloc heap is mapped.
 288      This will always be a valid file descriptor, since /dev/zero is used
 289      by default if no open file is supplied by the client.  Also note that
 290      it may change each time the region is mapped and unmapped. */
 291
 292   int fd;
 293
 294   /* An array of keys to data within the mapped region, for use by the
 295      application.  */
 296
 297   PTR keys[MMALLOC_KEYS];
 298
 299 };
 300
 301 /* Bits to look at in the malloc descriptor flags word */
 302
 303 #define MMALLOC_DEVZERO         (1 << 0)        /* Have mapped to /dev/zero */
 304 #define MMALLOC_INITIALIZED     (1 << 1)        /* Initialized mmalloc */
 305 #define MMALLOC_MMCHECK_USED    (1 << 2)        /* mmcheck() called already */
 306
 307 /* Internal version of `mfree' used in `morecore'. */
 308
 309 extern void __mmalloc_free PARAMS ((struct mdesc *, PTR));
 310
 311 /* Hooks for debugging versions.  */
 312
 313 extern void (*__mfree_hook) PARAMS ((PTR, PTR));
 314 extern PTR (*__mmalloc_hook) PARAMS ((PTR, size_t));
 315 extern PTR (*__mrealloc_hook) PARAMS ((PTR, PTR, size_t));
 316
 317 /* A default malloc descriptor for the single sbrk() managed region. */
 318
 319 extern struct mdesc *__mmalloc_default_mdp;
 320
 321 /* Initialize the first use of the default malloc descriptor, which uses
 322    an sbrk() region. */
 323
 324 extern struct mdesc *__mmalloc_sbrk_init PARAMS ((void));
 325
 326 /* Grow or shrink a contiguous mapped region using mmap().
 327    Works much like sbrk() */
 328
 329 #if defined(HAVE_MMAP)
 330
 331 extern PTR __mmalloc_mmap_morecore PARAMS ((struct mdesc *, int));
 332
 333 #endif
 334
 335 /* Remap a mmalloc region that was previously mapped. */
 336
 337 extern PTR __mmalloc_remap_core PARAMS ((struct mdesc *));
 338
 339 /* Macro to convert from a user supplied malloc descriptor to pointer to the
 340    internal malloc descriptor.  If the user supplied descriptor is NULL, then
 341    use the default internal version, initializing it if necessary.  Otherwise
 342    just cast the user supplied version (which is void *) to the proper type
 343    (struct mdesc *). */
 344
 345 #define MD_TO_MDP(md) \
 346   ((md) == NULL \
 347    ? (__mmalloc_default_mdp == NULL \
 348       ? __mmalloc_sbrk_init () \
 349       : __mmalloc_default_mdp) \
 350    : (struct mdesc *) (md))
 351
 352 #endif  /* __MMPRIVATE_H */