lib/xmalloc.c

   1 /* xmalloc.c -- malloc with out of memory checking
   2
   3    Copyright (C) 1990-2000, 2002-2006, 2008-2020 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 #include <config.h>
  19
  20 #define XALLOC_INLINE _GL_EXTERN_INLINE
  21
  22 #include "xalloc.h"
  23
  24 #include <stdlib.h>
  25 #include <string.h>
  26
  27 /* 1 if calloc, malloc and realloc are known to be compatible with GNU.
  28    This matters if we are not also using the calloc-gnu, malloc-gnu
  29    and realloc-gnu modules, which define HAVE_CALLOC_GNU,
  30    HAVE_MALLOC_GNU and HAVE_REALLOC_GNU and support the GNU API even
  31    on non-GNU platforms.  */
  32 #if defined HAVE_CALLOC_GNU || (defined __GLIBC__ && !defined __UCLIBC__)
  33 enum { HAVE_GNU_CALLOC = 1 };
  34 #else
  35 enum { HAVE_GNU_CALLOC = 0 };
  36 #endif
  37 #if defined HAVE_MALLOC_GNU || (defined __GLIBC__ && !defined __UCLIBC__)
  38 enum { HAVE_GNU_MALLOC = 1 };
  39 #else
  40 enum { HAVE_GNU_MALLOC = 0 };
  41 #endif
  42 #if defined HAVE_REALLOC_GNU || (defined __GLIBC__ && !defined __UCLIBC__)
  43 enum { HAVE_GNU_REALLOC = 1 };
  44 #else
  45 enum { HAVE_GNU_REALLOC = 0 };
  46 #endif
  47
  48 /* Allocate N bytes of memory dynamically, with error checking.  */
  49
  50 void *
  51 xmalloc (size_t n)
  52 {
  53   void *p = malloc (n);
  54   if (!p && (HAVE_GNU_MALLOC || n))
  55     xalloc_die ();
  56   return p;
  57 }
  58
  59 /* Change the size of an allocated block of memory P to N bytes,
  60    with error checking.  */
  61
  62 void *
  63 xrealloc (void *p, size_t n)
  64 {
  65   if (!HAVE_GNU_REALLOC && !n && p)
  66     {
  67       /* The GNU and C99 realloc behaviors disagree here.  Act like GNU.  */
  68       free (p);
  69       return NULL;
  70     }
  71
  72   void *r = realloc (p, n);
  73   if (!r && (n || (HAVE_GNU_REALLOC && !p)))
  74     xalloc_die ();
  75   return r;
  76 }
  77
  78 /* If P is null, allocate a block of at least *PN bytes; otherwise,
  79    reallocate P so that it contains more than *PN bytes.  *PN must be
  80    nonzero unless P is null.  Set *PN to the new block's size, and
  81    return the pointer to the new block.  *PN is never set to zero, and
  82    the returned pointer is never null.  */
  83
  84 void *
  85 x2realloc (void *p, size_t *pn)
  86 {
  87   return x2nrealloc (p, pn, 1);
  88 }
  89
  90 /* Allocate N bytes of zeroed memory dynamically, with error checking.
  91    There's no need for xnzalloc (N, S), since it would be equivalent
  92    to xcalloc (N, S).  */
  93
  94 void *
  95 xzalloc (size_t n)
  96 {
  97   return xcalloc (n, 1);
  98 }
  99
 100 /* Allocate zeroed memory for N elements of S bytes, with error
 101    checking.  S must be nonzero.  */
 102
 103 void *
 104 xcalloc (size_t n, size_t s)
 105 {
 106   void *p;
 107   /* Test for overflow, since objects with size greater than
 108      PTRDIFF_MAX cause pointer subtraction to go awry.  Omit size-zero
 109      tests if HAVE_GNU_CALLOC, since GNU calloc never returns NULL if
 110      successful.  */
 111   if (xalloc_oversized (n, s)
 112       || (! (p = calloc (n, s)) && (HAVE_GNU_CALLOC || n != 0)))
 113     xalloc_die ();
 114   return p;
 115 }
 116
 117 /* Clone an object P of size S, with error checking.  There's no need
 118    for xnmemdup (P, N, S), since xmemdup (P, N * S) works without any
 119    need for an arithmetic overflow check.  */
 120
 121 void *
 122 xmemdup (void const *p, size_t s)
 123 {
 124   return memcpy (xmalloc (s), p, s);
 125 }
 126
 127 /* Clone STRING.  */
 128
 129 char *
 130 xstrdup (char const *string)
 131 {
 132   return xmemdup (string, strlen (string) + 1);
 133 }