lib/xalloc.h

   1 /* xalloc.h -- malloc with out-of-memory checking
   2
   3    Copyright (C) 1990-2000, 2003-2004, 2006-2020 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #ifndef XALLOC_H_
  19 #define XALLOC_H_
  20
  21 #include <stddef.h>
  22 #include <stdint.h>
  23
  24 #include "xalloc-oversized.h"
  25
  26 #ifndef _GL_INLINE_HEADER_BEGIN
  27  #error "Please include config.h first."
  28 #endif
  29 _GL_INLINE_HEADER_BEGIN
  30 #ifndef XALLOC_INLINE
  31 # define XALLOC_INLINE _GL_INLINE
  32 #endif
  33
  34
  35 #ifdef __cplusplus
  36 extern "C" {
  37 #endif
  38
  39
  40 #if GNULIB_XALLOC_DIE
  41
  42 /* This function is always triggered when memory is exhausted.
  43    It must be defined by the application, either explicitly
  44    or by using gnulib's xalloc-die module.  This is the
  45    function to call when one wants the program to die because of a
  46    memory allocation failure.  */
  47 /*extern*/ _Noreturn void xalloc_die (void);
  48
  49 #endif /* GNULIB_XALLOC_DIE */
  50
  51 #if GNULIB_XALLOC
  52
  53 void *xmalloc (size_t s)
  54       _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_ALLOC_SIZE ((1));
  55 void *xzalloc (size_t s)
  56       _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_ALLOC_SIZE ((1));
  57 void *xcalloc (size_t n, size_t s)
  58       _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_ALLOC_SIZE ((1, 2));
  59 void *xrealloc (void *p, size_t s)
  60       _GL_ATTRIBUTE_ALLOC_SIZE ((2));
  61 void *x2realloc (void *p, size_t *pn);
  62 void *xmemdup (void const *p, size_t s)
  63       _GL_ATTRIBUTE_ALLOC_SIZE ((2));
  64 char *xstrdup (char const *str)
  65       _GL_ATTRIBUTE_MALLOC;
  66
  67 /* In the following macros, T must be an elementary or structure/union or
  68    typedef'ed type, or a pointer to such a type.  To apply one of the
  69    following macros to a function pointer or array type, you need to typedef
  70    it first and use the typedef name.  */
  71
  72 /* Allocate an object of type T dynamically, with error checking.  */
  73 /* extern t *XMALLOC (typename t); */
  74 # define XMALLOC(t) ((t *) xmalloc (sizeof (t)))
  75
  76 /* Allocate memory for N elements of type T, with error checking.  */
  77 /* extern t *XNMALLOC (size_t n, typename t); */
  78 # define XNMALLOC(n, t) \
  79     ((t *) (sizeof (t) == 1 ? xmalloc (n) : xnmalloc (n, sizeof (t))))
  80
  81 /* Allocate an object of type T dynamically, with error checking,
  82    and zero it.  */
  83 /* extern t *XZALLOC (typename t); */
  84 # define XZALLOC(t) ((t *) xzalloc (sizeof (t)))
  85
  86 /* Allocate memory for N elements of type T, with error checking,
  87    and zero it.  */
  88 /* extern t *XCALLOC (size_t n, typename t); */
  89 # define XCALLOC(n, t) \
  90     ((t *) (sizeof (t) == 1 ? xzalloc (n) : xcalloc (n, sizeof (t))))
  91
  92
  93 /* Allocate an array of N objects, each with S bytes of memory,
  94    dynamically, with error checking.  S must be nonzero.  */
  95
  96 XALLOC_INLINE void *xnmalloc (size_t n, size_t s)
  97                     _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_ALLOC_SIZE ((1, 2));
  98 XALLOC_INLINE void *
  99 xnmalloc (size_t n, size_t s)
 100 {
 101   if (xalloc_oversized (n, s))
 102     xalloc_die ();
 103   return xmalloc (n * s);
 104 }
 105
 106 /* Change the size of an allocated block of memory P to an array of N
 107    objects each of S bytes, with error checking.  S must be nonzero.  */
 108
 109 XALLOC_INLINE void *xnrealloc (void *p, size_t n, size_t s)
 110                     _GL_ATTRIBUTE_ALLOC_SIZE ((2, 3));
 111 XALLOC_INLINE void *
 112 xnrealloc (void *p, size_t n, size_t s)
 113 {
 114   if (xalloc_oversized (n, s))
 115     xalloc_die ();
 116   return xrealloc (p, n * s);
 117 }
 118
 119 /* If P is null, allocate a block of at least *PN such objects;
 120    otherwise, reallocate P so that it contains more than *PN objects
 121    each of S bytes.  S must be nonzero.  Set *PN to the new number of
 122    objects, and return the pointer to the new block.  *PN is never set
 123    to zero, and the returned pointer is never null.
 124
 125    Repeated reallocations are guaranteed to make progress, either by
 126    allocating an initial block with a nonzero size, or by allocating a
 127    larger block.
 128
 129    In the following implementation, nonzero sizes are increased by a
 130    factor of approximately 1.5 so that repeated reallocations have
 131    O(N) overall cost rather than O(N**2) cost, but the
 132    specification for this function does not guarantee that rate.
 133
 134    Here is an example of use:
 135
 136      int *p = NULL;
 137      size_t used = 0;
 138      size_t allocated = 0;
 139
 140      void
 141      append_int (int value)
 142        {
 143          if (used == allocated)
 144            p = x2nrealloc (p, &allocated, sizeof *p);
 145          p[used++] = value;
 146        }
 147
 148    This causes x2nrealloc to allocate a block of some nonzero size the
 149    first time it is called.
 150
 151    To have finer-grained control over the initial size, set *PN to a
 152    nonzero value before calling this function with P == NULL.  For
 153    example:
 154
 155      int *p = NULL;
 156      size_t used = 0;
 157      size_t allocated = 0;
 158      size_t allocated1 = 1000;
 159
 160      void
 161      append_int (int value)
 162        {
 163          if (used == allocated)
 164            {
 165              p = x2nrealloc (p, &allocated1, sizeof *p);
 166              allocated = allocated1;
 167            }
 168          p[used++] = value;
 169        }
 170
 171    */
 172
 173 XALLOC_INLINE void *
 174 x2nrealloc (void *p, size_t *pn, size_t s)
 175 {
 176   size_t n = *pn;
 177
 178   if (! p)
 179     {
 180       if (! n)
 181         {
 182           /* The approximate size to use for initial small allocation
 183              requests, when the invoking code specifies an old size of
 184              zero.  This is the largest "small" request for the GNU C
 185              library malloc.  */
 186           enum { DEFAULT_MXFAST = 64 * sizeof (size_t) / 4 };
 187
 188           n = DEFAULT_MXFAST / s;
 189           n += !n;
 190         }
 191       if (xalloc_oversized (n, s))
 192         xalloc_die ();
 193     }
 194   else
 195     {
 196       /* Set N = floor (1.5 * N) + 1 so that progress is made even if N == 0.
 197          Check for overflow, so that N * S stays in both ptrdiff_t and
 198          size_t range.  The check may be slightly conservative, but an
 199          exact check isn't worth the trouble.  */
 200       if ((PTRDIFF_MAX < SIZE_MAX ? PTRDIFF_MAX : SIZE_MAX) / 3 * 2 / s
 201           <= n)
 202         xalloc_die ();
 203       n += n / 2 + 1;
 204     }
 205
 206   *pn = n;
 207   return xrealloc (p, n * s);
 208 }
 209
 210 /* Return a pointer to a new buffer of N bytes.  This is like xmalloc,
 211    except it returns char *.  */
 212
 213 XALLOC_INLINE char *xcharalloc (size_t n)
 214                     _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_ALLOC_SIZE ((1));
 215 XALLOC_INLINE char *
 216 xcharalloc (size_t n)
 217 {
 218   return XNMALLOC (n, char);
 219 }
 220
 221 #endif /* GNULIB_XALLOC */
 222
 223
 224 #ifdef __cplusplus
 225 }
 226 #endif
 227
 228
 229 #if GNULIB_XALLOC && defined __cplusplus
 230
 231 /* C++ does not allow conversions from void * to other pointer types
 232    without a cast.  Use templates to work around the problem when
 233    possible.  */
 234
 235 template <typename T> inline T *
 236 xrealloc (T *p, size_t s)
 237 {
 238   return (T *) xrealloc ((void *) p, s);
 239 }
 240
 241 template <typename T> inline T *
 242 xnrealloc (T *p, size_t n, size_t s)
 243 {
 244   return (T *) xnrealloc ((void *) p, n, s);
 245 }
 246
 247 template <typename T> inline T *
 248 x2realloc (T *p, size_t *pn)
 249 {
 250   return (T *) x2realloc ((void *) p, pn);
 251 }
 252
 253 template <typename T> inline T *
 254 x2nrealloc (T *p, size_t *pn, size_t s)
 255 {
 256   return (T *) x2nrealloc ((void *) p, pn, s);
 257 }
 258
 259 template <typename T> inline T *
 260 xmemdup (T const *p, size_t s)
 261 {
 262   return (T *) xmemdup ((void const *) p, s);
 263 }
 264
 265 #endif /* GNULIB_XALLOC && C++ */
 266
 267
 268 _GL_INLINE_HEADER_END
 269
 270 #endif /* !XALLOC_H_ */