1 /* vasprintf and asprintf with out-of-memory checking.
2 Copyright (C) 1999, 2002-2004, 2006 Free Software Foundation, Inc.
3
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
7 any later version.
8
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
13
14 You should have received a copy of the GNU General Public License along
15 with this program; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
17
18 #include <config.h>
19
20 /* Specification. */
21 #include "xvasprintf.h"
22
23 #include <errno.h>
24 #include <limits.h>
25 #include <string.h>
26
27 #include "vasprintf.h"
28 #include "xalloc.h"
29
30 /* Checked size_t computations. */
31 #include "xsize.h"
32
33 /* Some systems, like OSF/1 4.0 and Woe32, don't have EOVERFLOW. */
34 #ifndef EOVERFLOW
35 # define EOVERFLOW E2BIG
36 #endif
37
38 static inline char *
xstrcat(size_t argcount,va_list args)39 xstrcat (size_t argcount, va_list args)
40 {
41 char *result;
42 va_list ap;
43 size_t totalsize;
44 size_t i;
45 char *p;
46
47 /* Determine the total size. */
48 totalsize = 0;
49 va_copy (ap, args);
50 for (i = argcount; i > 0; i--)
51 {
52 const char *next = va_arg (ap, const char *);
53 totalsize = xsum (totalsize, strlen (next));
54 }
55 va_end (ap);
56
57 /* Test for overflow in the summing pass above or in (totalsize + 1) below.
58 Also, don't return a string longer than INT_MAX, for consistency with
59 vasprintf(). */
60 if (totalsize == SIZE_MAX || totalsize > INT_MAX)
61 {
62 errno = EOVERFLOW;
63 return NULL;
64 }
65
66 /* Allocate and fill the result string. */
67 result = (char *) xmalloc (totalsize + 1);
68 p = result;
69 for (i = argcount; i > 0; i--)
70 {
71 const char *next = va_arg (args, const char *);
72 size_t len = strlen (next);
73 memcpy (p, next, len);
74 p += len;
75 }
76 *p = '\0';
77
78 return result;
79 }
80
81 char *
xvasprintf(const char * format,va_list args)82 xvasprintf (const char *format, va_list args)
83 {
84 char *result;
85
86 /* Recognize the special case format = "%s...%s". It is a frequently used
87 idiom for string concatenation and needs to be fast. We don't want to
88 have a separate function xstrcat() for this purpose. */
89 {
90 size_t argcount = 0;
91 const char *f;
92
93 for (f = format;;)
94 {
95 if (*f == '\0')
96 /* Recognized the special case of string concatenation. */
97 return xstrcat (argcount, args);
98 if (*f != '%')
99 break;
100 f++;
101 if (*f != 's')
102 break;
103 f++;
104 argcount++;
105 }
106 }
107
108 if (vasprintf (&result, format, args) < 0)
109 {
110 if (errno == ENOMEM)
111 xalloc_die ();
112 return NULL;
113 }
114
115 return result;
116 }
117