contrib/cvs-1.12/lib/xmalloc.c

   1 /* xmalloc.c -- malloc with out of memory checking
   2
   3    Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   4    1999, 2000, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software Foundation,
  18    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include "xalloc.h"
  25
  26 #include <stdlib.h>
  27 #include <string.h>
  28
  29 #ifndef SIZE_MAX
  30 # define SIZE_MAX ((size_t) -1)
  31 #endif
  32
  33 /* 1 if calloc is known to be compatible with GNU calloc.  This
  34    matters if we are not also using the calloc module, which defines
  35    HAVE_CALLOC and supports the GNU API even on non-GNU platforms.  */
  36 #if defined HAVE_CALLOC || defined __GLIBC__
  37 enum { HAVE_GNU_CALLOC = 1 };
  38 #else
  39 enum { HAVE_GNU_CALLOC = 0 };
  40 #endif
  41
  42 /* Allocate an array of N objects, each with S bytes of memory,
  43    dynamically, with error checking.  S must be nonzero.  */
  44
  45 static inline void *
  46 xnmalloc_inline (size_t n, size_t s)
  47 {
  48   void *p;
  49   if (xalloc_oversized (n, s) || (! (p = malloc (n * s)) && n != 0))
  50     xalloc_die ();
  51   return p;
  52 }
  53
  54 void *
  55 xnmalloc (size_t n, size_t s)
  56 {
  57   return xnmalloc_inline (n, s);
  58 }
  59
  60 /* Allocate N bytes of memory dynamically, with error checking.  */
  61
  62 void *
  63 xmalloc (size_t n)
  64 {
  65   return xnmalloc_inline (n, 1);
  66 }
  67
  68 /* Change the size of an allocated block of memory P to an array of N
  69    objects each of S bytes, with error checking.  S must be nonzero.  */
  70
  71 static inline void *
  72 xnrealloc_inline (void *p, size_t n, size_t s)
  73 {
  74   if (xalloc_oversized (n, s) || (! (p = realloc (p, n * s)) && n != 0))
  75     xalloc_die ();
  76   return p;
  77 }
  78
  79 void *
  80 xnrealloc (void *p, size_t n, size_t s)
  81 {
  82   return xnrealloc_inline (p, n, s);
  83 }
  84
  85 /* Change the size of an allocated block of memory P to N bytes,
  86    with error checking.  */
  87
  88 void *
  89 xrealloc (void *p, size_t n)
  90 {
  91   return xnrealloc_inline (p, n, 1);
  92 }
  93
  94
  95 /* If P is null, allocate a block of at least *PN such objects;
  96    otherwise, reallocate P so that it contains more than *PN objects
  97    each of S bytes.  *PN must be nonzero unless P is null, and S must
  98    be nonzero.  Set *PN to the new number of objects, and return the
  99    pointer to the new block.  *PN is never set to zero, and the
 100    returned pointer is never null.
 101
 102    Repeated reallocations are guaranteed to make progress, either by
 103    allocating an initial block with a nonzero size, or by allocating a
 104    larger block.
 105
 106    In the following implementation, nonzero sizes are doubled so that
 107    repeated reallocations have O(N log N) overall cost rather than
 108    O(N**2) cost, but the specification for this function does not
 109    guarantee that sizes are doubled.
 110
 111    Here is an example of use:
 112
 113      int *p = NULL;
 114      size_t used = 0;
 115      size_t allocated = 0;
 116
 117      void
 118      append_int (int value)
 119        {
 120          if (used == allocated)
 121            p = x2nrealloc (p, &allocated, sizeof *p);
 122          p[used++] = value;
 123        }
 124
 125    This causes x2nrealloc to allocate a block of some nonzero size the
 126    first time it is called.
 127
 128    To have finer-grained control over the initial size, set *PN to a
 129    nonzero value before calling this function with P == NULL.  For
 130    example:
 131
 132      int *p = NULL;
 133      size_t used = 0;
 134      size_t allocated = 0;
 135      size_t allocated1 = 1000;
 136
 137      void
 138      append_int (int value)
 139        {
 140          if (used == allocated)
 141            {
 142              p = x2nrealloc (p, &allocated1, sizeof *p);
 143              allocated = allocated1;
 144            }
 145          p[used++] = value;
 146        }
 147
 148    */
 149
 150 static inline void *
 151 x2nrealloc_inline (void *p, size_t *pn, size_t s)
 152 {
 153   size_t n = *pn;
 154
 155   if (! p)
 156     {
 157       if (! n)
 158         {
 159           /* The approximate size to use for initial small allocation
 160              requests, when the invoking code specifies an old size of
 161              zero.  64 bytes is the largest "small" request for the
 162              GNU C library malloc.  */
 163           enum { DEFAULT_MXFAST = 64 };
 164
 165           n = DEFAULT_MXFAST / s;
 166           n += !n;
 167         }
 168     }
 169   else
 170     {
 171       if (SIZE_MAX / 2 / s < n)
 172         xalloc_die ();
 173       n *= 2;
 174     }
 175
 176   *pn = n;
 177   return xrealloc (p, n * s);
 178 }
 179
 180 void *
 181 x2nrealloc (void *p, size_t *pn, size_t s)
 182 {
 183   return x2nrealloc_inline (p, pn, s);
 184 }
 185
 186 /* If P is null, allocate a block of at least *PN bytes; otherwise,
 187    reallocate P so that it contains more than *PN bytes.  *PN must be
 188    nonzero unless P is null.  Set *PN to the new block's size, and
 189    return the pointer to the new block.  *PN is never set to zero, and
 190    the returned pointer is never null.  */
 191
 192 void *
 193 x2realloc (void *p, size_t *pn)
 194 {
 195   return x2nrealloc_inline (p, pn, 1);
 196 }
 197
 198 /* Allocate S bytes of zeroed memory dynamically, with error checking.
 199    There's no need for xnzalloc (N, S), since it would be equivalent
 200    to xcalloc (N, S).  */
 201
 202 void *
 203 xzalloc (size_t s)
 204 {
 205   return memset (xmalloc (s), 0, s);
 206 }
 207
 208 /* Allocate zeroed memory for N elements of S bytes, with error
 209    checking.  S must be nonzero.  */
 210
 211 void *
 212 xcalloc (size_t n, size_t s)
 213 {
 214   void *p;
 215   /* Test for overflow, since some calloc implementations don't have
 216      proper overflow checks.  But omit overflow and size-zero tests if
 217      HAVE_GNU_CALLOC, since GNU calloc catches overflow and never
 218      returns NULL if successful.  */
 219   if ((! HAVE_GNU_CALLOC && xalloc_oversized (n, s))
 220       || (! (p = calloc (n, s)) && (HAVE_GNU_CALLOC || n != 0)))
 221     xalloc_die ();
 222   return p;
 223 }
 224
 225 /* Clone an object P of size S, with error checking.  There's no need
 226    for xnmemdup (P, N, S), since xmemdup (P, N * S) works without any
 227    need for an arithmetic overflow check.  */
 228
 229 void *
 230 xmemdup (void const *p, size_t s)
 231 {
 232   return memcpy (xmalloc (s), p, s);
 233 }
 234
 235 /* Clone STRING.  */
 236
 237 char *
 238 xstrdup (char const *string)
 239 {
 240   return xmemdup (string, strlen (string) + 1);
 241 }