1 /* Construct a regular expression from a literal string.
2 Copyright (C) 1995, 2010-2021 Free Software Foundation, Inc.
3 Written by Bruno Haible <haible@clisp.cons.org>, 2010.
4
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
17
18 #include <config.h>
19
20 /* Specification. */
21 #include "regex-quote.h"
22
23 #include <string.h>
24
25 #include "mbuiter.h"
26 #include "xalloc.h"
27
28 /* Characters that are special in a BRE. */
29 static const char bre_special[] = "$^.*[]\\";
30
31 /* Characters that are special in an ERE. */
32 static const char ere_special[] = "$^.*[]\\+?{}()|";
33
34 struct regex_quote_spec
regex_quote_spec_posix(int cflags,bool anchored)35 regex_quote_spec_posix (int cflags, bool anchored)
36 {
37 struct regex_quote_spec result;
38
39 strcpy (result.special, cflags != 0 ? ere_special : bre_special);
40 result.multibyte = true;
41 result.anchored = anchored;
42
43 return result;
44 }
45
46 /* Syntax bit values, defined in GNU <regex.h>. We don't include it here,
47 otherwise this module would need to depend on gnulib module 'regex'. */
48 #define RE_BK_PLUS_QM 0x00000002
49 #define RE_INTERVALS 0x00000200
50 #define RE_LIMITED_OPS 0x00000400
51 #define RE_NEWLINE_ALT 0x00000800
52 #define RE_NO_BK_BRACES 0x00001000
53 #define RE_NO_BK_PARENS 0x00002000
54 #define RE_NO_BK_VBAR 0x00008000
55
56 struct regex_quote_spec
regex_quote_spec_gnu(unsigned long syntax,bool anchored)57 regex_quote_spec_gnu (unsigned long /*reg_syntax_t*/ syntax, bool anchored)
58 {
59 struct regex_quote_spec result;
60 char *p;
61
62 p = result.special;
63 memcpy (p, bre_special, sizeof (bre_special) - 1);
64 p += sizeof (bre_special) - 1;
65 if ((syntax & RE_LIMITED_OPS) == 0 && (syntax & RE_BK_PLUS_QM) == 0)
66 {
67 *p++ = '+';
68 *p++ = '?';
69 }
70 if ((syntax & RE_INTERVALS) != 0 && (syntax & RE_NO_BK_BRACES) != 0)
71 {
72 *p++ = '{';
73 *p++ = '}';
74 }
75 if ((syntax & RE_NO_BK_PARENS) != 0)
76 {
77 *p++ = '(';
78 *p++ = ')';
79 }
80 if ((syntax & RE_LIMITED_OPS) == 0 && (syntax & RE_NO_BK_VBAR) != 0)
81 *p++ = '|';
82 if ((syntax & RE_NEWLINE_ALT) != 0)
83 *p++ = '\n';
84 *p = '\0';
85
86 result.multibyte = true;
87 result.anchored = anchored;
88
89 return result;
90 }
91
92 /* Characters that are special in a PCRE. */
93 static const char pcre_special[] = "$^.*[]\\+?{}()|";
94
95 /* Options bit values, defined in <pcre.h>. We don't include it here, because
96 it is not a standard header. */
97 #define PCRE_ANCHORED 0x00000010
98 #define PCRE_EXTENDED 0x00000008
99
100 struct regex_quote_spec
regex_quote_spec_pcre(int options,bool anchored)101 regex_quote_spec_pcre (int options, bool anchored)
102 {
103 struct regex_quote_spec result;
104 char *p;
105
106 p = result.special;
107 memcpy (p, pcre_special, sizeof (pcre_special) - 1);
108 p += sizeof (pcre_special) - 1;
109 if (options & PCRE_EXTENDED)
110 {
111 *p++ = ' ';
112 *p++ = '\t';
113 *p++ = '\n';
114 *p++ = '\v';
115 *p++ = '\f';
116 *p++ = '\r';
117 *p++ = '#';
118 }
119 *p = '\0';
120
121 /* PCRE regular expressions consist of UTF-8 characters of options contains
122 PCRE_UTF8 and of single bytes otherwise. */
123 result.multibyte = false;
124 /* If options contains PCRE_ANCHORED, the anchoring is implicit. */
125 result.anchored = (options & PCRE_ANCHORED ? 0 : anchored);
126
127 return result;
128 }
129
130 size_t
regex_quote_length(const char * string,const struct regex_quote_spec * spec)131 regex_quote_length (const char *string, const struct regex_quote_spec *spec)
132 {
133 const char *special = spec->special;
134 size_t length;
135
136 length = 0;
137 if (spec->anchored)
138 length += 2; /* for '^' at the beginning and '$' at the end */
139 if (spec->multibyte)
140 {
141 mbui_iterator_t iter;
142
143 for (mbui_init (iter, string); mbui_avail (iter); mbui_advance (iter))
144 {
145 /* We know that special contains only ASCII characters. */
146 if (mb_len (mbui_cur (iter)) == 1
147 && strchr (special, * mbui_cur_ptr (iter)))
148 length += 1;
149 length += mb_len (mbui_cur (iter));
150 }
151 }
152 else
153 {
154 const char *iter;
155
156 for (iter = string; *iter != '\0'; iter++)
157 {
158 if (strchr (special, *iter))
159 length += 1;
160 length += 1;
161 }
162 }
163
164 return length;
165 }
166
167 char *
regex_quote_copy(char * p,const char * string,const struct regex_quote_spec * spec)168 regex_quote_copy (char *p, const char *string, const struct regex_quote_spec *spec)
169 {
170 const char *special = spec->special;
171
172 if (spec->anchored)
173 *p++ = '^';
174 if (spec->multibyte)
175 {
176 mbui_iterator_t iter;
177
178 for (mbui_init (iter, string); mbui_avail (iter); mbui_advance (iter))
179 {
180 /* We know that special contains only ASCII characters. */
181 if (mb_len (mbui_cur (iter)) == 1
182 && strchr (special, * mbui_cur_ptr (iter)))
183 *p++ = '\\';
184 memcpy (p, mbui_cur_ptr (iter), mb_len (mbui_cur (iter)));
185 p += mb_len (mbui_cur (iter));
186 }
187 }
188 else
189 {
190 const char *iter;
191
192 for (iter = string; *iter != '\0'; iter++)
193 {
194 if (strchr (special, *iter))
195 *p++ = '\\';
196 *p++ = *iter++;
197 }
198 }
199 if (spec->anchored)
200 *p++ = '$';
201
202 return p;
203 }
204
205 char *
regex_quote(const char * string,const struct regex_quote_spec * spec)206 regex_quote (const char *string, const struct regex_quote_spec *spec)
207 {
208 size_t length = regex_quote_length (string, spec);
209 char *result = XNMALLOC (length + 1, char);
210 char *p;
211
212 p = result;
213 p = regex_quote_copy (p, string, spec);
214 *p = '\0';
215 return result;
216 }
217