1 /* $OpenBSD: regsub.c,v 1.6 2023/06/30 21:55:09 nicm Exp $ */
2
3 /*
4 * Copyright (c) 2019 Nicholas Marriott <nicholas.marriott@gmail.com>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
15 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
16 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 #include <sys/types.h>
20
21 #include <regex.h>
22 #include <string.h>
23
24 #include "tmux.h"
25
26 static void
regsub_copy(char ** buf,ssize_t * len,const char * text,size_t start,size_t end)27 regsub_copy(char **buf, ssize_t *len, const char *text, size_t start, size_t end)
28 {
29 size_t add = end - start;
30
31 *buf = xrealloc(*buf, (*len) + add + 1);
32 memcpy((*buf) + *len, text + start, add);
33 (*len) += add;
34 }
35
36 static void
regsub_expand(char ** buf,ssize_t * len,const char * with,const char * text,regmatch_t * m,u_int n)37 regsub_expand(char **buf, ssize_t *len, const char *with, const char *text,
38 regmatch_t *m, u_int n)
39 {
40 const char *cp;
41 u_int i;
42
43 for (cp = with; *cp != '\0'; cp++) {
44 if (*cp == '\\') {
45 cp++;
46 if (*cp >= '0' && *cp <= '9') {
47 i = *cp - '0';
48 if (i < n && m[i].rm_so != m[i].rm_eo) {
49 regsub_copy(buf, len, text, m[i].rm_so,
50 m[i].rm_eo);
51 continue;
52 }
53 }
54 }
55 *buf = xrealloc(*buf, (*len) + 2);
56 (*buf)[(*len)++] = *cp;
57 }
58 }
59
60 char *
regsub(const char * pattern,const char * with,const char * text,int flags)61 regsub(const char *pattern, const char *with, const char *text, int flags)
62 {
63 regex_t r;
64 regmatch_t m[10];
65 ssize_t start, end, last, len = 0;
66 int empty = 0;
67 char *buf = NULL;
68
69 if (*text == '\0')
70 return (xstrdup(""));
71 if (regcomp(&r, pattern, flags) != 0)
72 return (NULL);
73
74 start = 0;
75 last = 0;
76 end = strlen(text);
77
78 while (start <= end) {
79 if (regexec(&r, text + start, nitems(m), m, 0) != 0) {
80 regsub_copy(&buf, &len, text, start, end);
81 break;
82 }
83
84 /*
85 * Append any text not part of this match (from the end of the
86 * last match).
87 */
88 regsub_copy(&buf, &len, text, last, m[0].rm_so + start);
89
90 /*
91 * If the last match was empty and this one isn't (it is either
92 * later or has matched text), expand this match. If it is
93 * empty, move on one character and try again from there.
94 */
95 if (empty ||
96 start + m[0].rm_so != last ||
97 m[0].rm_so != m[0].rm_eo) {
98 regsub_expand(&buf, &len, with, text + start, m,
99 nitems(m));
100
101 last = start + m[0].rm_eo;
102 start += m[0].rm_eo;
103 empty = 0;
104 } else {
105 last = start + m[0].rm_eo;
106 start += m[0].rm_eo + 1;
107 empty = 1;
108 }
109
110 /* Stop now if anchored to start. */
111 if (*pattern == '^') {
112 regsub_copy(&buf, &len, text, start, end);
113 break;
114 }
115 }
116 buf[len] = '\0';
117
118 regfree(&r);
119 return (buf);
120 }
121