1 /* $NetBSD: expandm.c,v 1.12 2019/01/24 22:07:14 mrg Exp $ */
2
3 /*-
4 * Copyright (c) 2019 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Christos Zoulas.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31 #include <sys/cdefs.h>
32 __RCSID("$NetBSD: expandm.c,v 1.12 2019/01/24 22:07:14 mrg Exp $");
33
34 #include <limits.h>
35 #include <stdio.h>
36 #include <string.h>
37 #include <stdlib.h>
38 #include <errno.h>
39
40 #include "expandm.h"
41
42 #ifdef TEST
43 #undef INT_MAX
44 #define INT_MAX 31
45 #endif
46
47
48 const char * __attribute__((__format_arg__(1)))
expandm(const char * fmt,const char * sf,char ** rbuf)49 expandm(const char *fmt, const char *sf, char **rbuf)
50 {
51 const int err = errno;
52 const char *e = NULL;
53 char *buf, *m, *nbuf;
54 const char *ptr;
55
56 buf = NULL;
57 for (ptr = fmt; (m = strstr(ptr, "%m")) != NULL; ptr = m + 2) {
58 size_t cnt = 0;
59 size_t nlen;
60
61 for (char *p = m; p >= ptr && *p == '%'; p--)
62 cnt++;
63
64 nlen = (size_t)(m - ptr);
65 /*
66 * we can't exceed INT_MAX because int is used as
67 * a format width
68 */
69 if (__predict_false(nlen >= INT_MAX)) {
70 size_t blen = buf ? strlen(buf) : 0;
71 size_t tlen;
72
73 /*
74 * if we would overflow a ptrdiff_t when computing
75 * tlen, then don't bother. The format string is
76 * simply too large to be converted.
77 */
78 if (blen >= PTRDIFF_MAX ||
79 nlen >= PTRDIFF_MAX - blen ||
80 nlen >= SIZE_T_MAX - blen)
81 goto out;
82
83 tlen = nlen + blen;
84
85 nbuf = realloc(buf, tlen + 1);
86 if (nbuf == NULL)
87 goto out;
88
89 memcpy(nbuf + blen, ptr, nlen);
90 nbuf[tlen] = '\0';
91 ptr += nlen;
92 buf = nbuf;
93 }
94
95 if (__predict_true(e == NULL && (cnt & 1) != 0))
96 e = strerror(err);
97 if (asprintf(&nbuf, "%s%.*s%s", buf ? buf : "",
98 (int)(m - ptr), ptr, (cnt & 1) ? e : "%m") == -1)
99 goto out;
100 free(buf);
101 buf = nbuf;
102 }
103
104 if (asprintf(&nbuf, "%s%s%s", buf ? buf : "", ptr, sf ? sf : "") == -1)
105 goto out;
106
107 free(buf);
108 if (rbuf)
109 *rbuf = nbuf;
110 errno = err;
111 return nbuf;
112 out:
113 free(buf);
114 if (rbuf)
115 *rbuf = NULL;
116 errno = err;
117 return fmt;
118 }
119
120 #ifdef TEST
121 int
main(int argc,char * argv[])122 main(int argc, char *argv[])
123 {
124 errno = ERANGE;
125 printf("%s\n", expandm(argc > 1 ? argv[1] : "Message %%m=%m: %%%m%%",
126 "...", NULL));
127 return 0;
128 }
129 #endif
130