1 /* $OpenBSD: rxp.c,v 1.8 2009/10/27 23:59:26 deraadt Exp $ */
2 /* $NetBSD: rxp.c,v 1.5 1995/04/22 10:17:00 cgd Exp $ */
3
4 /*-
5 * Copyright (c) 1991, 1993
6 * The Regents of the University of California. All rights reserved.
7 *
8 * This code is derived from software contributed to Berkeley by
9 * Jim R. Oldroyd at The Instruction Set and Keith Gabryelski at
10 * Commodore Business Machines.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37 /*
38 * regular expression parser
39 *
40 * external functions and return values are:
41 * rxp_compile(s)
42 * TRUE success
43 * FALSE parse failure; error message will be in char rxperr[]
44 * metas are:
45 * {...} optional pattern, equialent to [...|]
46 * | alternate pattern
47 * [...] pattern delimiters
48 *
49 * rxp_match(s)
50 * TRUE string s matches compiled pattern
51 * FALSE match failure or regexp error
52 *
53 * rxp_expand()
54 * char * reverse-engineered regular expression string
55 * NULL regexp error
56 */
57
58 #include <stdio.h>
59 #include <ctype.h>
60 #include "quiz.h"
61 /* regexp tokens, arg */
62 #define LIT (-1) /* literal character, char */
63 #define SOT (-2) /* start text anchor, - */
64 #define EOT (-3) /* end text anchor, - */
65 #define GRP_S (-4) /* start alternate grp, ptr_to_end */
66 #define GRP_E (-5) /* end group, - */
67 #define ALT_S (-6) /* alternate starts, ptr_to_next */
68 #define ALT_E (-7) /* alternate ends, - */
69 #define END (-8) /* end of regexp, - */
70
71 typedef short Rxp_t; /* type for regexp tokens */
72
73 static Rxp_t rxpbuf[RXP_LINE_SZ]; /* compiled regular expression buffer */
74 char rxperr[128]; /* parser error message */
75
76 static int rxp__compile(const char *, int);
77 static char *rxp__expand(int);
78 static int rxp__match(const char *, int, Rxp_t *, Rxp_t *, const char *);
79
80 int
rxp_compile(const char * s)81 rxp_compile(const char *s)
82 {
83 return (rxp__compile(s, TRUE));
84 }
85
86 static int
rxp__compile(const char * s,int first)87 rxp__compile(const char *s, int first)
88 {
89 static Rxp_t *rp;
90 static const char *sp;
91 Rxp_t *grp_ptr;
92 Rxp_t *alt_ptr;
93 int esc, err;
94
95 if (s == NULL) {
96 (void)snprintf(rxperr, sizeof(rxperr),
97 "null string sent to rxp_compile");
98 return(FALSE);
99 }
100 esc = 0;
101 if (first) {
102 rp = rxpbuf;
103 sp = s;
104 *rp++ = SOT; /* auto-anchor: pat is really ^pat$ */
105 *rp++ = GRP_S; /* auto-group: ^pat$ is really ^[pat]$ */
106 *rp++ = 0;
107 }
108 *rp++ = ALT_S;
109 alt_ptr = rp;
110 *rp++ = 0;
111 for (; *sp; ++sp) {
112 if (rp - rxpbuf >= RXP_LINE_SZ - 4) {
113 (void)snprintf(rxperr, sizeof(rxperr),
114 "regular expression too long %s", s);
115 return (FALSE);
116 }
117 if (*sp == ':' && !esc)
118 break;
119 if (esc) {
120 *rp++ = LIT;
121 *rp++ = *sp;
122 esc = 0;
123 }
124 else switch (*sp) {
125 case '\\':
126 esc = 1;
127 break;
128 case '{':
129 case '[':
130 *rp++ = GRP_S;
131 grp_ptr = rp;
132 *rp++ = 0;
133 sp++;
134 if ((err = rxp__compile(s, FALSE)) != TRUE)
135 return (err);
136 *rp++ = GRP_E;
137 *grp_ptr = rp - rxpbuf;
138 break;
139 case '}':
140 case ']':
141 case '|':
142 *rp++ = ALT_E;
143 *alt_ptr = rp - rxpbuf;
144 if (*sp != ']') {
145 *rp++ = ALT_S;
146 alt_ptr = rp;
147 *rp++ = 0;
148 }
149 if (*sp != '|') {
150 if (*sp != ']') {
151 *rp++ = ALT_E;
152 *alt_ptr = rp - rxpbuf;
153 }
154 if (first) {
155 (void)snprintf(rxperr, sizeof(rxperr),
156 "unmatched alternator in regexp %s",
157 s);
158 return (FALSE);
159 }
160 return (TRUE);
161 }
162 break;
163 default:
164 *rp++ = LIT;
165 *rp++ = *sp;
166 esc = 0;
167 break;
168 }
169 }
170 if (!first) {
171 (void)snprintf(rxperr, sizeof(rxperr),
172 "unmatched alternator in regexp %s", s);
173 return (FALSE);
174 }
175 *rp++ = ALT_E;
176 *alt_ptr = rp - rxpbuf;
177 *rp++ = GRP_E;
178 *(rxpbuf + 2) = rp - rxpbuf;
179 *rp++ = EOT;
180 *rp = END;
181 return (TRUE);
182 }
183
184 /*
185 * match string against compiled regular expression
186 */
187 int
rxp_match(const char * s)188 rxp_match(const char *s)
189 {
190 return (rxp__match(s, TRUE, NULL, NULL, NULL));
191 }
192
193 /*
194 * j_succ : jump here on successful alt match
195 * j_fail : jump here on failed match
196 * sp_fail: reset sp to here on failed match
197 */
198 static int
rxp__match(const char * s,int first,Rxp_t * j_succ,Rxp_t * j_fail,const char * sp_fail)199 rxp__match(const char *s, int first, Rxp_t *j_succ, Rxp_t *j_fail,
200 const char *sp_fail)
201 {
202 static Rxp_t *rp;
203 static const char *sp;
204 int ch;
205 Rxp_t *grp_end = NULL;
206 int err;
207
208 if (first) {
209 rp = rxpbuf;
210 sp = s;
211 }
212 while (rp < rxpbuf + RXP_LINE_SZ && *rp != END)
213 switch(*rp) {
214 case LIT:
215 rp++;
216 ch = isascii(*rp) && isupper(*rp) ? tolower(*rp) : *rp;
217 if (ch != *sp++) {
218 rp = j_fail;
219 sp = sp_fail;
220 return (TRUE);
221 }
222 rp++;
223 break;
224 case SOT:
225 if (sp != s)
226 return (FALSE);
227 rp++;
228 break;
229 case EOT:
230 if (*sp != 0)
231 return (FALSE);
232 rp++;
233 break;
234 case GRP_S:
235 rp++;
236 grp_end = rxpbuf + *rp++;
237 break;
238 case ALT_S:
239 rp++;
240 if ((err = rxp__match(sp,
241 FALSE, grp_end, rxpbuf + *rp++, sp)) != TRUE)
242 return (err);
243 break;
244 case ALT_E:
245 rp = j_succ;
246 return (TRUE);
247 case GRP_E:
248 default:
249 return (FALSE);
250 }
251 return (*rp != END ? FALSE : TRUE);
252 }
253
254 /*
255 * Reverse engineer the regular expression, by picking first of all alternates.
256 */
257 char *
rxp_expand(void)258 rxp_expand(void)
259 {
260 return (rxp__expand(TRUE));
261 }
262
263 static char *
rxp__expand(int first)264 rxp__expand(int first)
265 {
266 static char buf[RXP_LINE_SZ/2];
267 static Rxp_t *rp;
268 static char *bp;
269 Rxp_t *grp_ptr;
270 char *err;
271
272 if (first) {
273 rp = rxpbuf;
274 bp = buf;
275 }
276 while (rp < rxpbuf + RXP_LINE_SZ && *rp != END)
277 switch(*rp) {
278 case LIT:
279 rp++;
280 *bp++ = *rp++;
281 break;
282 case GRP_S:
283 rp++;
284 grp_ptr = rxpbuf + *rp;
285 rp++;
286 if ((err = rxp__expand(FALSE)) == NULL)
287 return (err);
288 rp = grp_ptr;
289 break;
290 case ALT_E:
291 return (buf);
292 case ALT_S:
293 rp++;
294 /* FALLTHROUGH */
295 case SOT:
296 case EOT:
297 case GRP_E:
298 rp++;
299 break;
300 default:
301 return (NULL);
302 }
303 if (first) {
304 if (*rp != END)
305 return (NULL);
306 *bp = '\0';
307 }
308 return (buf);
309 }
310