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