1 /* xmalloc.c -- malloc with out of memory checking
3 Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
4 1999, 2000, 2002, 2003, 2004, 2005, 2006 Free Software Foundation,
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 This program 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
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software Foundation,
19 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
29 # define SIZE_MAX ((size_t) -1)
32 /* 1 if calloc is known to be compatible with GNU calloc. This
33 matters if we are not also using the calloc module, which defines
34 HAVE_CALLOC and supports the GNU API even on non-GNU platforms. */
35 #if defined HAVE_CALLOC || defined __GLIBC__
36 enum { HAVE_GNU_CALLOC = 1 };
38 enum { HAVE_GNU_CALLOC = 0 };
41 /* Allocate an array of N objects, each with S bytes of memory,
42 dynamically, with error checking. S must be nonzero. */
45 xnmalloc_inline (size_t n, size_t s)
48 if (xalloc_oversized (n, s) || (! (p = malloc (n * s)) && n != 0))
54 xnmalloc (size_t n, size_t s)
56 return xnmalloc_inline (n, s);
59 /* Allocate N bytes of memory dynamically, with error checking. */
64 return xnmalloc_inline (n, 1);
67 /* Change the size of an allocated block of memory P to an array of N
68 objects each of S bytes, with error checking. S must be nonzero. */
71 xnrealloc_inline (void *p, size_t n, size_t s)
73 if (xalloc_oversized (n, s) || (! (p = realloc (p, n * s)) && n != 0))
79 xnrealloc (void *p, size_t n, size_t s)
81 return xnrealloc_inline (p, n, s);
84 /* Change the size of an allocated block of memory P to N bytes,
85 with error checking. */
88 xrealloc (void *p, size_t n)
90 return xnrealloc_inline (p, n, 1);
94 /* If P is null, allocate a block of at least *PN such objects;
95 otherwise, reallocate P so that it contains more than *PN objects
96 each of S bytes. *PN must be nonzero unless P is null, and S must
97 be nonzero. Set *PN to the new number of objects, and return the
98 pointer to the new block. *PN is never set to zero, and the
99 returned pointer is never null.
101 Repeated reallocations are guaranteed to make progress, either by
102 allocating an initial block with a nonzero size, or by allocating a
105 In the following implementation, nonzero sizes are doubled so that
106 repeated reallocations have O(N log N) overall cost rather than
107 O(N**2) cost, but the specification for this function does not
108 guarantee that sizes are doubled.
110 Here is an example of use:
114 size_t allocated = 0;
117 append_int (int value)
119 if (used == allocated)
120 p = x2nrealloc (p, &allocated, sizeof *p);
124 This causes x2nrealloc to allocate a block of some nonzero size the
125 first time it is called.
127 To have finer-grained control over the initial size, set *PN to a
128 nonzero value before calling this function with P == NULL. For
133 size_t allocated = 0;
134 size_t allocated1 = 1000;
137 append_int (int value)
139 if (used == allocated)
141 p = x2nrealloc (p, &allocated1, sizeof *p);
142 allocated = allocated1;
150 x2nrealloc_inline (void *p, size_t *pn, size_t s)
158 /* The approximate size to use for initial small allocation
159 requests, when the invoking code specifies an old size of
160 zero. 64 bytes is the largest "small" request for the
161 GNU C library malloc. */
162 enum { DEFAULT_MXFAST = 64 };
164 n = DEFAULT_MXFAST / s;
170 if (SIZE_MAX / 2 / s < n)
176 return xrealloc (p, n * s);
180 x2nrealloc (void *p, size_t *pn, size_t s)
182 return x2nrealloc_inline (p, pn, s);
185 /* If P is null, allocate a block of at least *PN bytes; otherwise,
186 reallocate P so that it contains more than *PN bytes. *PN must be
187 nonzero unless P is null. Set *PN to the new block's size, and
188 return the pointer to the new block. *PN is never set to zero, and
189 the returned pointer is never null. */
192 x2realloc (void *p, size_t *pn)
194 return x2nrealloc_inline (p, pn, 1);
197 /* Allocate S bytes of zeroed memory dynamically, with error checking.
198 There's no need for xnzalloc (N, S), since it would be equivalent
199 to xcalloc (N, S). */
204 return memset (xmalloc (s), 0, s);
207 /* Allocate zeroed memory for N elements of S bytes, with error
208 checking. S must be nonzero. */
211 xcalloc (size_t n, size_t s)
214 /* Test for overflow, since some calloc implementations don't have
215 proper overflow checks. But omit overflow and size-zero tests if
216 HAVE_GNU_CALLOC, since GNU calloc catches overflow and never
217 returns NULL if successful. */
218 if ((! HAVE_GNU_CALLOC && xalloc_oversized (n, s))
219 || (! (p = calloc (n, s)) && (HAVE_GNU_CALLOC || n != 0)))
224 /* Clone an object P of size S, with error checking. There's no need
225 for xnmemdup (P, N, S), since xmemdup (P, N * S) works without any
226 need for an arithmetic overflow check. */
229 xmemdup (void const *p, size_t s)
231 return memcpy (xmalloc (s), p, s);
237 xstrdup (char const *string)
239 return xmemdup (string, strlen (string) + 1);