Line data Source code
1 : /* xalloc.h -- malloc with out-of-memory checking
2 :
3 : Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
4 : 1999, 2000, 2003, 2004, 2006, 2007, 2008 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 3 of the License, or
9 : (at your option) 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, see <http://www.gnu.org/licenses/>. */
18 :
19 : #ifndef XALLOC_H_
20 : # define XALLOC_H_
21 :
22 : # include <stddef.h>
23 :
24 :
25 : # ifdef __cplusplus
26 : extern "C" {
27 : # endif
28 :
29 :
30 : # ifndef __attribute__
31 : # if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 8)
32 : # define __attribute__(x)
33 : # endif
34 : # endif
35 :
36 : # ifndef ATTRIBUTE_NORETURN
37 : # define ATTRIBUTE_NORETURN __attribute__ ((__noreturn__))
38 : # endif
39 :
40 : /* This function is always triggered when memory is exhausted.
41 : It must be defined by the application, either explicitly
42 : or by using gnulib's xalloc-die module. This is the
43 : function to call when one wants the program to die because of a
44 : memory allocation failure. */
45 : extern void xalloc_die (void) ATTRIBUTE_NORETURN;
46 :
47 : void *xmalloc (size_t s);
48 : void *xzalloc (size_t s);
49 : void *xcalloc (size_t n, size_t s);
50 : void *xrealloc (void *p, size_t s);
51 : void *x2realloc (void *p, size_t *pn);
52 : void *xmemdup (void const *p, size_t s);
53 : char *xstrdup (char const *str);
54 :
55 : /* Return 1 if an array of N objects, each of size S, cannot exist due
56 : to size arithmetic overflow. S must be positive and N must be
57 : nonnegative. This is a macro, not an inline function, so that it
58 : works correctly even when SIZE_MAX < N.
59 :
60 : By gnulib convention, SIZE_MAX represents overflow in size
61 : calculations, so the conservative dividend to use here is
62 : SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
63 : However, malloc (SIZE_MAX) fails on all known hosts where
64 : sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
65 : exactly-SIZE_MAX allocations on such hosts; this avoids a test and
66 : branch when S is known to be 1. */
67 : # define xalloc_oversized(n, s) \
68 : ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
69 :
70 :
71 : /* In the following macros, T must be an elementary or structure/union or
72 : typedef'ed type, or a pointer to such a type. To apply one of the
73 : following macros to a function pointer or array type, you need to typedef
74 : it first and use the typedef name. */
75 :
76 : /* Allocate an object of type T dynamically, with error checking. */
77 : /* extern t *XMALLOC (typename t); */
78 : # define XMALLOC(t) ((t *) xmalloc (sizeof (t)))
79 :
80 : /* Allocate memory for N elements of type T, with error checking. */
81 : /* extern t *XNMALLOC (size_t n, typename t); */
82 : # define XNMALLOC(n, t) \
83 : ((t *) (sizeof (t) == 1 ? xmalloc (n) : xnmalloc (n, sizeof (t))))
84 :
85 : /* Allocate an object of type T dynamically, with error checking,
86 : and zero it. */
87 : /* extern t *XZALLOC (typename t); */
88 : # define XZALLOC(t) ((t *) xzalloc (sizeof (t)))
89 :
90 : /* Allocate memory for N elements of type T, with error checking,
91 : and zero it. */
92 : /* extern t *XCALLOC (size_t n, typename t); */
93 : # define XCALLOC(n, t) \
94 : ((t *) (sizeof (t) == 1 ? xzalloc (n) : xcalloc (n, sizeof (t))))
95 :
96 :
97 : # if HAVE_INLINE
98 : # define static_inline static inline
99 : # else
100 : void *xnmalloc (size_t n, size_t s);
101 : void *xnrealloc (void *p, size_t n, size_t s);
102 : void *x2nrealloc (void *p, size_t *pn, size_t s);
103 : char *xcharalloc (size_t n);
104 : # endif
105 :
106 : # ifdef static_inline
107 :
108 : /* Allocate an array of N objects, each with S bytes of memory,
109 : dynamically, with error checking. S must be nonzero. */
110 :
111 : static_inline void *
112 941 : xnmalloc (size_t n, size_t s)
113 : {
114 941 : if (xalloc_oversized (n, s))
115 0 : xalloc_die ();
116 941 : return xmalloc (n * s);
117 : }
118 :
119 : /* Change the size of an allocated block of memory P to an array of N
120 : objects each of S bytes, with error checking. S must be nonzero. */
121 :
122 : static_inline void *
123 18 : xnrealloc (void *p, size_t n, size_t s)
124 : {
125 18 : if (xalloc_oversized (n, s))
126 0 : xalloc_die ();
127 18 : return xrealloc (p, n * s);
128 : }
129 :
130 : /* If P is null, allocate a block of at least *PN such objects;
131 : otherwise, reallocate P so that it contains more than *PN objects
132 : each of S bytes. *PN must be nonzero unless P is null, and S must
133 : be nonzero. Set *PN to the new number of objects, and return the
134 : pointer to the new block. *PN is never set to zero, and the
135 : returned pointer is never null.
136 :
137 : Repeated reallocations are guaranteed to make progress, either by
138 : allocating an initial block with a nonzero size, or by allocating a
139 : larger block.
140 :
141 : In the following implementation, nonzero sizes are increased by a
142 : factor of approximately 1.5 so that repeated reallocations have
143 : O(N) overall cost rather than O(N**2) cost, but the
144 : specification for this function does not guarantee that rate.
145 :
146 : Here is an example of use:
147 :
148 : int *p = NULL;
149 : size_t used = 0;
150 : size_t allocated = 0;
151 :
152 : void
153 : append_int (int value)
154 : {
155 : if (used == allocated)
156 : p = x2nrealloc (p, &allocated, sizeof *p);
157 : p[used++] = value;
158 : }
159 :
160 : This causes x2nrealloc to allocate a block of some nonzero size the
161 : first time it is called.
162 :
163 : To have finer-grained control over the initial size, set *PN to a
164 : nonzero value before calling this function with P == NULL. For
165 : example:
166 :
167 : int *p = NULL;
168 : size_t used = 0;
169 : size_t allocated = 0;
170 : size_t allocated1 = 1000;
171 :
172 : void
173 : append_int (int value)
174 : {
175 : if (used == allocated)
176 : {
177 : p = x2nrealloc (p, &allocated1, sizeof *p);
178 : allocated = allocated1;
179 : }
180 : p[used++] = value;
181 : }
182 :
183 : */
184 :
185 : static_inline void *
186 1149 : x2nrealloc (void *p, size_t *pn, size_t s)
187 : {
188 1149 : size_t n = *pn;
189 :
190 1149 : if (! p)
191 : {
192 1034 : if (! n)
193 : {
194 : /* The approximate size to use for initial small allocation
195 : requests, when the invoking code specifies an old size of
196 : zero. 64 bytes is the largest "small" request for the
197 : GNU C library malloc. */
198 : enum { DEFAULT_MXFAST = 64 };
199 :
200 1020 : n = DEFAULT_MXFAST / s;
201 1020 : n += !n;
202 : }
203 : }
204 : else
205 : {
206 : /* Set N = ceil (1.5 * N) so that progress is made if N == 1.
207 : Check for overflow, so that N * S stays in size_t range.
208 : The check is slightly conservative, but an exact check isn't
209 : worth the trouble. */
210 115 : if ((size_t) -1 / 3 * 2 / s <= n)
211 0 : xalloc_die ();
212 115 : n += (n + 1) / 2;
213 : }
214 :
215 1149 : *pn = n;
216 1149 : return xrealloc (p, n * s);
217 : }
218 :
219 : /* Return a pointer to a new buffer of N bytes. This is like xmalloc,
220 : except it returns char *. */
221 :
222 : static_inline char *
223 153 : xcharalloc (size_t n)
224 : {
225 153 : return XNMALLOC (n, char);
226 : }
227 :
228 : # endif
229 :
230 : # ifdef __cplusplus
231 : }
232 :
233 : /* C++ does not allow conversions from void * to other pointer types
234 : without a cast. Use templates to work around the problem when
235 : possible. */
236 :
237 : template <typename T> inline T *
238 : xrealloc (T *p, size_t s)
239 : {
240 : return (T *) xrealloc ((void *) p, s);
241 : }
242 :
243 : template <typename T> inline T *
244 : xnrealloc (T *p, size_t n, size_t s)
245 : {
246 : return (T *) xnrealloc ((void *) p, n, s);
247 : }
248 :
249 : template <typename T> inline T *
250 : x2realloc (T *p, size_t *pn)
251 : {
252 : return (T *) x2realloc ((void *) p, pn);
253 : }
254 :
255 : template <typename T> inline T *
256 : x2nrealloc (T *p, size_t *pn, size_t s)
257 : {
258 : return (T *) x2nrealloc ((void *) p, pn, s);
259 : }
260 :
261 : template <typename T> inline T *
262 : xmemdup (T const *p, size_t s)
263 : {
264 : return (T *) xmemdup ((void const *) p, s);
265 : }
266 :
267 : # endif
268 :
269 :
270 : #endif /* !XALLOC_H_ */
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