1*9742b58aSmrg /* $NetBSD: expandm.c,v 1.12 2019/01/24 22:07:14 mrg Exp $ */
2de284403Schristos
3de284403Schristos /*-
472194717Skre * Copyright (c) 2019 The NetBSD Foundation, Inc.
5de284403Schristos * All rights reserved.
6de284403Schristos *
7de284403Schristos * This code is derived from software contributed to The NetBSD Foundation
8de284403Schristos * by Christos Zoulas.
9de284403Schristos *
10de284403Schristos * Redistribution and use in source and binary forms, with or without
11de284403Schristos * modification, are permitted provided that the following conditions
12de284403Schristos * are met:
13de284403Schristos * 1. Redistributions of source code must retain the above copyright
14de284403Schristos * notice, this list of conditions and the following disclaimer.
15de284403Schristos * 2. Redistributions in binary form must reproduce the above copyright
16de284403Schristos * notice, this list of conditions and the following disclaimer in the
17de284403Schristos * documentation and/or other materials provided with the distribution.
18de284403Schristos *
19de284403Schristos * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20de284403Schristos * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21de284403Schristos * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22de284403Schristos * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23de284403Schristos * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24de284403Schristos * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25de284403Schristos * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26de284403Schristos * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27de284403Schristos * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28de284403Schristos * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29de284403Schristos * POSSIBILITY OF SUCH DAMAGE.
30de284403Schristos */
31de284403Schristos #include <sys/cdefs.h>
32*9742b58aSmrg __RCSID("$NetBSD: expandm.c,v 1.12 2019/01/24 22:07:14 mrg Exp $");
33de284403Schristos
3451621f70Schristos #include <limits.h>
35de284403Schristos #include <stdio.h>
36de284403Schristos #include <string.h>
37de284403Schristos #include <stdlib.h>
38de284403Schristos #include <errno.h>
39de284403Schristos
40de284403Schristos #include "expandm.h"
41de284403Schristos
4251621f70Schristos #ifdef TEST
4351621f70Schristos #undef INT_MAX
4451621f70Schristos #define INT_MAX 31
4551621f70Schristos #endif
4651621f70Schristos
4751621f70Schristos
480f2ce139Skre const char * __attribute__((__format_arg__(1)))
expandm(const char * fmt,const char * sf,char ** rbuf)49c5cf555eSchristos expandm(const char *fmt, const char *sf, char **rbuf)
50de284403Schristos {
51f1ee8649Skre const int err = errno;
52f1ee8649Skre const char *e = NULL;
53de284403Schristos char *buf, *m, *nbuf;
54de284403Schristos const char *ptr;
55de284403Schristos
5672194717Skre buf = NULL;
5772194717Skre for (ptr = fmt; (m = strstr(ptr, "%m")) != NULL; ptr = m + 2) {
58de284403Schristos size_t cnt = 0;
59b0c40852Skre size_t nlen;
6051621f70Schristos
61de284403Schristos for (char *p = m; p >= ptr && *p == '%'; p--)
62de284403Schristos cnt++;
6351621f70Schristos
64b0c40852Skre nlen = (size_t)(m - ptr);
65b31f5e70Schristos /*
66b31f5e70Schristos * we can't exceed INT_MAX because int is used as
67b31f5e70Schristos * a format width
68b31f5e70Schristos */
69b31f5e70Schristos if (__predict_false(nlen >= INT_MAX)) {
70b31f5e70Schristos size_t blen = buf ? strlen(buf) : 0;
71d35fae1dSkre size_t tlen;
72d35fae1dSkre
73d35fae1dSkre /*
74d35fae1dSkre * if we would overflow a ptrdiff_t when computing
75d35fae1dSkre * tlen, then don't bother. The format string is
76d35fae1dSkre * simply too large to be converted.
77d35fae1dSkre */
78d35fae1dSkre if (blen >= PTRDIFF_MAX ||
79d35fae1dSkre nlen >= PTRDIFF_MAX - blen ||
80d35fae1dSkre nlen >= SIZE_T_MAX - blen)
81d35fae1dSkre goto out;
82d35fae1dSkre
83d35fae1dSkre tlen = nlen + blen;
8451621f70Schristos
85b31f5e70Schristos nbuf = realloc(buf, tlen + 1);
8651621f70Schristos if (nbuf == NULL)
8751621f70Schristos goto out;
8851621f70Schristos
8951621f70Schristos memcpy(nbuf + blen, ptr, nlen);
90b31f5e70Schristos nbuf[tlen] = '\0';
9151621f70Schristos ptr += nlen;
9251621f70Schristos buf = nbuf;
9351621f70Schristos }
9451621f70Schristos
95f1ee8649Skre if (__predict_true(e == NULL && (cnt & 1) != 0))
96f1ee8649Skre e = strerror(err);
97de284403Schristos if (asprintf(&nbuf, "%s%.*s%s", buf ? buf : "",
98d501129cSchristos (int)(m - ptr), ptr, (cnt & 1) ? e : "%m") == -1)
99de284403Schristos goto out;
100de284403Schristos free(buf);
101de284403Schristos buf = nbuf;
102de284403Schristos }
103de284403Schristos
104de284403Schristos if (asprintf(&nbuf, "%s%s%s", buf ? buf : "", ptr, sf ? sf : "") == -1)
105de284403Schristos goto out;
106de284403Schristos
107de284403Schristos free(buf);
108c5cf555eSchristos if (rbuf)
109bd7d4285Skre *rbuf = nbuf;
110f1ee8649Skre errno = err;
111de284403Schristos return nbuf;
112de284403Schristos out:
113de284403Schristos free(buf);
114c5cf555eSchristos if (rbuf)
115c5cf555eSchristos *rbuf = NULL;
116f1ee8649Skre errno = err;
1170f2ce139Skre return fmt;
118de284403Schristos }
119de284403Schristos
120de284403Schristos #ifdef TEST
121de284403Schristos int
main(int argc,char * argv[])122de284403Schristos main(int argc, char *argv[])
123de284403Schristos {
124de284403Schristos errno = ERANGE;
1250f2ce139Skre printf("%s\n", expandm(argc > 1 ? argv[1] : "Message %%m=%m: %%%m%%",
1260f2ce139Skre "...", NULL));
127de284403Schristos return 0;
128de284403Schristos }
129de284403Schristos #endif
130