1 /*	$OpenBSD: engine.c,v 1.15 2005/08/05 13:03:00 espie Exp $	*/
2 
3 /*-
4  * Copyright (c) 1992, 1993, 1994 Henry Spencer.
5  * Copyright (c) 1992, 1993, 1994
6  *	The Regents of the University of California.  All rights reserved.
7  *
8  * This code is derived from software contributed to Berkeley by
9  * Henry Spencer.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  *
35  *	@(#)engine.c	8.5 (Berkeley) 3/20/94
36  */
37 
38 /*
39  * The matching engine and friends.  This file is #included by regexec.c
40  * after suitable #defines of a variety of macros used herein, so that
41  * different state representations can be used without duplicating masses
42  * of code.
43  */
44 
45 #ifdef SNAMES
46 #define	matcher	smatcher
47 #define	fast	sfast
48 #define	slow	sslow
49 #define	dissect	sdissect
50 #define	backref	sbackref
51 #define	step	sstep
52 #define	print	sprint
53 #define	at	sat
54 #define	match	smat
55 #define	nope	snope
56 #endif
57 #ifdef LNAMES
58 #define	matcher	lmatcher
59 #define	fast	lfast
60 #define	slow	lslow
61 #define	dissect	ldissect
62 #define	backref	lbackref
63 #define	step	lstep
64 #define	print	lprint
65 #define	at	lat
66 #define	match	lmat
67 #define	nope	lnope
68 #endif
69 
70 /* another structure passed up and down to avoid zillions of parameters */
71 struct match {
72 	struct re_guts *g;
73 	int eflags;
74 	regmatch_t *pmatch;	/* [nsub+1] (0 element unused) */
75 	char *offp;		/* offsets work from here */
76 	char *beginp;		/* start of string -- virtual NUL precedes */
77 	char *endp;		/* end of string -- virtual NUL here */
78 	char *coldp;		/* can be no match starting before here */
79 	char **lastpos;		/* [nplus+1] */
80 	STATEVARS;
81 	states st;		/* current states */
82 	states fresh;		/* states for a fresh start */
83 	states tmp;		/* temporary */
84 	states empty;		/* empty set of states */
85 };
86 
87 static int matcher(struct re_guts *, char *, size_t, regmatch_t[], int);
88 static char *dissect(struct match *, char *, char *, sopno, sopno);
89 static char *backref(struct match *, char *, char *, sopno, sopno, sopno, int);
90 static char *fast(struct match *, char *, char *, sopno, sopno);
91 static char *slow(struct match *, char *, char *, sopno, sopno);
92 static states step(struct re_guts *, sopno, sopno, states, int, states);
93 #define MAX_RECURSION	100
94 #define	BOL	(OUT+1)
95 #define	EOL	(BOL+1)
96 #define	BOLEOL	(BOL+2)
97 #define	NOTHING	(BOL+3)
98 #define	BOW	(BOL+4)
99 #define	EOW	(BOL+5)
100 #define	CODEMAX	(BOL+5)		/* highest code used */
101 #define	NONCHAR(c)	((c) > CHAR_MAX)
102 #define	NNONCHAR	(CODEMAX-CHAR_MAX)
103 #ifdef REDEBUG
104 static void print(struct match *, char *, states, int, FILE *);
105 #endif
106 #ifdef REDEBUG
107 static void at(struct match *, char *, char *, char *, sopno, sopno);
108 #endif
109 #ifdef REDEBUG
110 static char *pchar(int);
111 #endif
112 
113 #ifdef REDEBUG
114 #define	SP(t, s, c)	print(m, t, s, c, stdout)
115 #define	AT(t, p1, p2, s1, s2)	at(m, t, p1, p2, s1, s2)
116 #define	NOTE(str)	{ if (m->eflags&REG_TRACE) (void)printf("=%s\n", (str)); }
117 static int nope = 0;
118 #else
119 #define	SP(t, s, c)	/* nothing */
120 #define	AT(t, p1, p2, s1, s2)	/* nothing */
121 #define	NOTE(s)	/* nothing */
122 #endif
123 
124 /*
125  - matcher - the actual matching engine
126  */
127 static int			/* 0 success, REG_NOMATCH failure */
matcher(struct re_guts * g,char * string,size_t nmatch,regmatch_t pmatch[],int eflags)128 matcher(struct re_guts *g, char *string, size_t nmatch, regmatch_t pmatch[],
129     int eflags)
130 {
131 	char *endp;
132 	int i;
133 	struct match mv;
134 	struct match *m = &mv;
135 	char *dp;
136 	const sopno gf = g->firststate+1;	/* +1 for OEND */
137 	const sopno gl = g->laststate;
138 	char *start;
139 	char *stop;
140 
141 	/* simplify the situation where possible */
142 	if (g->cflags&REG_NOSUB)
143 		nmatch = 0;
144 	if (eflags&REG_STARTEND) {
145 		start = string + pmatch[0].rm_so;
146 		stop = string + pmatch[0].rm_eo;
147 	} else {
148 		start = string;
149 		stop = start + strlen(start);
150 	}
151 	if (stop < start)
152 		return(REG_INVARG);
153 
154 	/* prescreening; this does wonders for this rather slow code */
155 	if (g->must != NULL) {
156 		for (dp = start; dp < stop; dp++)
157 			if (*dp == g->must[0] && stop - dp >= g->mlen &&
158 				memcmp(dp, g->must, (size_t)g->mlen) == 0)
159 				break;
160 		if (dp == stop)		/* we didn't find g->must */
161 			return(REG_NOMATCH);
162 	}
163 
164 	/* match struct setup */
165 	m->g = g;
166 	m->eflags = eflags;
167 	m->pmatch = NULL;
168 	m->lastpos = NULL;
169 	m->offp = string;
170 	m->beginp = start;
171 	m->endp = (char*)stop;
172 	STATESETUP(m, 4);
173 	SETUP(m->st);
174 	SETUP(m->fresh);
175 	SETUP(m->tmp);
176 	SETUP(m->empty);
177 	CLEAR(m->empty);
178 
179 	/* this loop does only one repetition except for backrefs */
180 	for (;;) {
181 		endp = fast(m, start, stop, gf, gl);
182 		if (endp == NULL) {		/* a miss */
183 			free(m->pmatch);
184 			free(m->lastpos);
185 			STATETEARDOWN(m);
186 			return(REG_NOMATCH);
187 		}
188 		if (nmatch == 0 && !g->backrefs)
189 			break;		/* no further info needed */
190 
191 		/* where? */
192 		assert(m->coldp != NULL);
193 		for (;;) {
194 			NOTE("finding start");
195 			endp = slow(m, m->coldp, stop, gf, gl);
196 			if (endp != NULL)
197 				break;
198 			assert(m->coldp < m->endp);
199 			m->coldp++;
200 		}
201 		if (nmatch == 1 && !g->backrefs)
202 			break;		/* no further info needed */
203 
204 		/* oh my, he wants the subexpressions... */
205 		if (m->pmatch == NULL)
206 			m->pmatch = (regmatch_t *)malloc((m->g->nsub + 1) *
207 							sizeof(regmatch_t));
208 		if (m->pmatch == NULL) {
209 			STATETEARDOWN(m);
210 			return(REG_ESPACE);
211 		}
212 		for (i = 1; i <= (int)m->g->nsub; i++)
213 			m->pmatch[i].rm_so = m->pmatch[i].rm_eo = -1;
214 		if (!g->backrefs && !(m->eflags&REG_BACKR)) {
215 			NOTE("dissecting");
216 			dp = dissect(m, m->coldp, endp, gf, gl);
217 		} else {
218 			if (g->nplus > 0 && m->lastpos == NULL)
219 				m->lastpos = (char **)malloc((g->nplus+1) *
220 							sizeof(char *));
221 			if (g->nplus > 0 && m->lastpos == NULL) {
222 				free(m->pmatch);
223 				STATETEARDOWN(m);
224 				return(REG_ESPACE);
225 			}
226 			NOTE("backref dissect");
227 			dp = backref(m, m->coldp, endp, gf, gl, (sopno)0, 0);
228 		}
229 		if (dp != NULL)
230 			break;
231 
232 		/* uh-oh... we couldn't find a subexpression-level match */
233 		assert(g->backrefs);	/* must be back references doing it */
234 		assert(g->nplus == 0 || m->lastpos != NULL);
235 		for (;;) {
236 			if (dp != NULL || endp <= m->coldp)
237 				break;		/* defeat */
238 			NOTE("backoff");
239 			endp = slow(m, m->coldp, endp-1, gf, gl);
240 			if (endp == NULL)
241 				break;		/* defeat */
242 			/* try it on a shorter possibility */
243 #ifndef NDEBUG
244 			for (i = 1; i <= m->g->nsub; i++) {
245 				assert(m->pmatch[i].rm_so == -1);
246 				assert(m->pmatch[i].rm_eo == -1);
247 			}
248 #endif
249 			NOTE("backoff dissect");
250 			dp = backref(m, m->coldp, endp, gf, gl, (sopno)0, 0);
251 		}
252 		assert(dp == NULL || dp == endp);
253 		if (dp != NULL)		/* found a shorter one */
254 			break;
255 
256 		/* despite initial appearances, there is no match here */
257 		NOTE("false alarm");
258 		if (m->coldp == stop)
259 			break;
260 		start = m->coldp + 1;	/* recycle starting later */
261 	}
262 
263 	/* fill in the details if requested */
264 	if (nmatch > 0) {
265 		pmatch[0].rm_so = m->coldp - m->offp;
266 		pmatch[0].rm_eo = endp - m->offp;
267 	}
268 	if (nmatch > 1) {
269 		assert(m->pmatch != NULL);
270 		for (i = 1; i < (ssize_t)nmatch; i++)
271 			if (i <= (int)m->g->nsub)
272 				pmatch[i] = m->pmatch[i];
273 			else {
274 				pmatch[i].rm_so = -1;
275 				pmatch[i].rm_eo = -1;
276 			}
277 	}
278 
279 	if (m->pmatch != NULL)
280 		free((char *)m->pmatch);
281 	if (m->lastpos != NULL)
282 		free((char *)m->lastpos);
283 	STATETEARDOWN(m);
284 	return(0);
285 }
286 
287 /*
288  - dissect - figure out what matched what, no back references
289  */
290 static char *			/* == stop (success) always */
dissect(struct match * m,char * start,char * stop,sopno startst,sopno stopst)291 dissect(struct match *m, char *start, char *stop, sopno startst, sopno stopst)
292 {
293 	int i;
294 	sopno ss;	/* start sop of current subRE */
295 	sopno es;	/* end sop of current subRE */
296 	char *sp;	/* start of string matched by it */
297 	char *stp;	/* string matched by it cannot pass here */
298 	char *rest;	/* start of rest of string */
299 	char *tail;	/* string unmatched by rest of RE */
300 	sopno ssub;	/* start sop of subsubRE */
301 	sopno esub;	/* end sop of subsubRE */
302 	char *ssp;	/* start of string matched by subsubRE */
303 	char *sep;	/* end of string matched by subsubRE */
304 	char *oldssp;	/* previous ssp */
305 
306 	AT("diss", start, stop, startst, stopst);
307 	sp = start;
308 	for (ss = startst; ss < stopst; ss = es) {
309 		/* identify end of subRE */
310 		es = ss;
311 		switch (OP(m->g->strip[es])) {
312 		case OPLUS_:
313 		case OQUEST_:
314 			es += OPND(m->g->strip[es]);
315 			break;
316 		case OCH_:
317 			while (OP(m->g->strip[es]) != O_CH)
318 				es += OPND(m->g->strip[es]);
319 			break;
320 		}
321 		es++;
322 
323 		/* figure out what it matched */
324 		switch (OP(m->g->strip[ss])) {
325 		case OEND:
326 			assert(nope);
327 			break;
328 		case OCHAR:
329 			sp++;
330 			break;
331 		case OBOL:
332 		case OEOL:
333 		case OBOW:
334 		case OEOW:
335 			break;
336 		case OANY:
337 		case OANYOF:
338 			sp++;
339 			break;
340 		case OBACK_:
341 		case O_BACK:
342 			assert(nope);
343 			break;
344 		/* cases where length of match is hard to find */
345 		case OQUEST_:
346 			stp = stop;
347 			for (;;) {
348 				/* how long could this one be? */
349 				rest = slow(m, sp, stp, ss, es);
350 				assert(rest != NULL);	/* it did match */
351 				/* could the rest match the rest? */
352 				tail = slow(m, rest, stop, es, stopst);
353 				if (tail == stop)
354 					break;		/* yes! */
355 				/* no -- try a shorter match for this one */
356 				stp = rest - 1;
357 				assert(stp >= sp);	/* it did work */
358 			}
359 			ssub = ss + 1;
360 			esub = es - 1;
361 			/* did innards match? */
362 			if (slow(m, sp, rest, ssub, esub) != NULL) {
363 				if (dissect(m, sp, rest, ssub, esub) != rest) {
364 					assert(0 && "dissect(...) should return rest");
365 				}
366 			} else		/* no */
367 				assert(sp == rest);
368 			sp = rest;
369 			break;
370 		case OPLUS_:
371 			stp = stop;
372 			for (;;) {
373 				/* how long could this one be? */
374 				rest = slow(m, sp, stp, ss, es);
375 				assert(rest != NULL);	/* it did match */
376 				/* could the rest match the rest? */
377 				tail = slow(m, rest, stop, es, stopst);
378 				if (tail == stop)
379 					break;		/* yes! */
380 				/* no -- try a shorter match for this one */
381 				stp = rest - 1;
382 				assert(stp >= sp);	/* it did work */
383 			}
384 			ssub = ss + 1;
385 			esub = es - 1;
386 			ssp = sp;
387 			oldssp = ssp;
388 			for (;;) {	/* find last match of innards */
389 				sep = slow(m, ssp, rest, ssub, esub);
390 				if (sep == NULL || sep == ssp)
391 					break;	/* failed or matched null */
392 				oldssp = ssp;	/* on to next try */
393 				ssp = sep;
394 			}
395 			if (sep == NULL) {
396 				/* last successful match */
397 				sep = ssp;
398 				ssp = oldssp;
399 			}
400 			assert(sep == rest);	/* must exhaust substring */
401 			assert(slow(m, ssp, sep, ssub, esub) == rest);
402 			if (dissect(m, ssp, sep, ssub, esub) != sep) {
403 				assert(0 && "dissect(...) should return sep");
404 			}
405 			sp = rest;
406 			break;
407 		case OCH_:
408 			stp = stop;
409 			for (;;) {
410 				/* how long could this one be? */
411 				rest = slow(m, sp, stp, ss, es);
412 				assert(rest != NULL);	/* it did match */
413 				/* could the rest match the rest? */
414 				tail = slow(m, rest, stop, es, stopst);
415 				if (tail == stop)
416 					break;		/* yes! */
417 				/* no -- try a shorter match for this one */
418 				stp = rest - 1;
419 				assert(stp >= sp);	/* it did work */
420 			}
421 			ssub = ss + 1;
422 			esub = ss + OPND(m->g->strip[ss]) - 1;
423 			assert(OP(m->g->strip[esub]) == OOR1);
424 			for (;;) {	/* find first matching branch */
425 				if (slow(m, sp, rest, ssub, esub) == rest)
426 					break;	/* it matched all of it */
427 				/* that one missed, try next one */
428 				assert(OP(m->g->strip[esub]) == OOR1);
429 				esub++;
430 				assert(OP(m->g->strip[esub]) == OOR2);
431 				ssub = esub + 1;
432 				esub += OPND(m->g->strip[esub]);
433 				if (OP(m->g->strip[esub]) == OOR2)
434 					esub--;
435 				else
436 					assert(OP(m->g->strip[esub]) == O_CH);
437 			}
438 			if (dissect(m, sp, rest, ssub, esub) != rest) {
439 				assert(0 && "dissect(...) should return rest");
440 			}
441 			sp = rest;
442 			break;
443 		case O_PLUS:
444 		case O_QUEST:
445 		case OOR1:
446 		case OOR2:
447 		case O_CH:
448 			assert(nope);
449 			break;
450 		case OLPAREN:
451 			i = OPND(m->g->strip[ss]);
452 			assert(0 < i && i <= m->g->nsub);
453 			m->pmatch[i].rm_so = sp - m->offp;
454 			break;
455 		case ORPAREN:
456 			i = OPND(m->g->strip[ss]);
457 			assert(0 < i && i <= m->g->nsub);
458 			m->pmatch[i].rm_eo = sp - m->offp;
459 			break;
460 		default:		/* uh oh */
461 			assert(nope);
462 			break;
463 		}
464 	}
465 
466 	assert(sp == stop);
467 	return(sp);
468 }
469 
470 /*
471  - backref - figure out what matched what, figuring in back references
472  */
473 static char *			/* == stop (success) or NULL (failure) */
backref(struct match * m,char * start,char * stop,sopno startst,sopno stopst,sopno lev,int rec)474 backref(struct match *m, char *start, char *stop, sopno startst, sopno stopst,
475     sopno lev, int rec)			/* PLUS nesting level */
476 {
477 	int i;
478 	sopno ss;	/* start sop of current subRE */
479 	char *sp;	/* start of string matched by it */
480 	sopno ssub;	/* start sop of subsubRE */
481 	sopno esub;	/* end sop of subsubRE */
482 	char *ssp;	/* start of string matched by subsubRE */
483 	char *dp;
484 	size_t len;
485 	int hard;
486 	sop s;
487 	regoff_t offsave;
488 	cset *cs;
489 
490 	AT("back", start, stop, startst, stopst);
491 	sp = start;
492 
493 	/* get as far as we can with easy stuff */
494 	hard = 0;
495 	for (ss = startst; !hard && ss < stopst; ss++)
496 		switch (OP(s = m->g->strip[ss])) {
497 		case OCHAR:
498 			if (sp == stop || *sp++ != (char)OPND(s))
499 				return(NULL);
500 			break;
501 		case OANY:
502 			if (sp == stop)
503 				return(NULL);
504 			sp++;
505 			break;
506 		case OANYOF:
507 			cs = &m->g->sets[OPND(s)];
508 			if (sp == stop || !CHIN(cs, *sp++))
509 				return(NULL);
510 			break;
511 		case OBOL:
512 			if ( (sp == m->beginp && !(m->eflags&REG_NOTBOL)) ||
513 					(sp < m->endp && *(sp-1) == '\n' &&
514 						(m->g->cflags&REG_NEWLINE)) )
515 				{ /* yes */ }
516 			else
517 				return(NULL);
518 			break;
519 		case OEOL:
520 			if ( (sp == m->endp && !(m->eflags&REG_NOTEOL)) ||
521 					(sp < m->endp && *sp == '\n' &&
522 						(m->g->cflags&REG_NEWLINE)) )
523 				{ /* yes */ }
524 			else
525 				return(NULL);
526 			break;
527 		case OBOW:
528 			if (( (sp == m->beginp && !(m->eflags&REG_NOTBOL)) ||
529 					(sp < m->endp && *(sp-1) == '\n' &&
530 						(m->g->cflags&REG_NEWLINE)) ||
531 					(sp > m->beginp &&
532 							!ISWORD(*(sp-1))) ) &&
533 					(sp < m->endp && ISWORD(*sp)) )
534 				{ /* yes */ }
535 			else
536 				return(NULL);
537 			break;
538 		case OEOW:
539 			if (( (sp == m->endp && !(m->eflags&REG_NOTEOL)) ||
540 					(sp < m->endp && *sp == '\n' &&
541 						(m->g->cflags&REG_NEWLINE)) ||
542 					(sp < m->endp && !ISWORD(*sp)) ) &&
543 					(sp > m->beginp && ISWORD(*(sp-1))) )
544 				{ /* yes */ }
545 			else
546 				return(NULL);
547 			break;
548 		case O_QUEST:
549 			break;
550 		case OOR1:	/* matches null but needs to skip */
551 			ss++;
552 			s = m->g->strip[ss];
553 			do {
554 				assert(OP(s) == OOR2);
555 				ss += OPND(s);
556 			} while (OP(s = m->g->strip[ss]) != O_CH);
557 			/* note that the ss++ gets us past the O_CH */
558 			break;
559 		default:	/* have to make a choice */
560 			hard = 1;
561 			break;
562 		}
563 	if (!hard) {		/* that was it! */
564 		if (sp != stop)
565 			return(NULL);
566 		return(sp);
567 	}
568 	ss--;			/* adjust for the for's final increment */
569 
570 	/* the hard stuff */
571 	AT("hard", sp, stop, ss, stopst);
572 	s = m->g->strip[ss];
573 	switch (OP(s)) {
574 	case OBACK_:		/* the vilest depths */
575 		i = OPND(s);
576 		assert(0 < i && i <= m->g->nsub);
577 		if (m->pmatch[i].rm_eo == -1)
578 			return(NULL);
579 		assert(m->pmatch[i].rm_so != -1);
580 		len = m->pmatch[i].rm_eo - m->pmatch[i].rm_so;
581 		if (len == 0 && rec++ > MAX_RECURSION)
582 			return(NULL);
583 		assert(stop - m->beginp >= len);
584 		if (sp > stop - len)
585 			return(NULL);	/* not enough left to match */
586 		ssp = m->offp + m->pmatch[i].rm_so;
587 		if (memcmp(sp, ssp, len) != 0)
588 			return(NULL);
589 		while (m->g->strip[ss] != SOP(O_BACK, i))
590 			ss++;
591 		return(backref(m, sp+len, stop, ss+1, stopst, lev, rec));
592 		break;
593 	case OQUEST_:		/* to null or not */
594 		dp = backref(m, sp, stop, ss+1, stopst, lev, rec);
595 		if (dp != NULL)
596 			return(dp);	/* not */
597 		return(backref(m, sp, stop, ss+OPND(s)+1, stopst, lev, rec));
598 		break;
599 	case OPLUS_:
600 		assert(m->lastpos != NULL);
601 		assert(lev+1 <= m->g->nplus);
602 		m->lastpos[lev+1] = sp;
603 		return(backref(m, sp, stop, ss+1, stopst, lev+1, rec));
604 		break;
605 	case O_PLUS:
606 		if (sp == m->lastpos[lev])	/* last pass matched null */
607 			return(backref(m, sp, stop, ss+1, stopst, lev-1, rec));
608 		/* try another pass */
609 		m->lastpos[lev] = sp;
610 		dp = backref(m, sp, stop, ss-OPND(s)+1, stopst, lev, rec);
611 		if (dp == NULL)
612 			return(backref(m, sp, stop, ss+1, stopst, lev-1, rec));
613 		else
614 			return(dp);
615 		break;
616 	case OCH_:		/* find the right one, if any */
617 		ssub = ss + 1;
618 		esub = ss + OPND(s) - 1;
619 		assert(OP(m->g->strip[esub]) == OOR1);
620 		for (;;) {	/* find first matching branch */
621 			dp = backref(m, sp, stop, ssub, esub, lev, rec);
622 			if (dp != NULL)
623 				return(dp);
624 			/* that one missed, try next one */
625 			if (OP(m->g->strip[esub]) == O_CH)
626 				return(NULL);	/* there is none */
627 			esub++;
628 			assert(OP(m->g->strip[esub]) == OOR2);
629 			ssub = esub + 1;
630 			esub += OPND(m->g->strip[esub]);
631 			if (OP(m->g->strip[esub]) == OOR2)
632 				esub--;
633 			else
634 				assert(OP(m->g->strip[esub]) == O_CH);
635 		}
636 		break;
637 	case OLPAREN:		/* must undo assignment if rest fails */
638 		i = OPND(s);
639 		assert(0 < i && i <= m->g->nsub);
640 		offsave = m->pmatch[i].rm_so;
641 		m->pmatch[i].rm_so = sp - m->offp;
642 		dp = backref(m, sp, stop, ss+1, stopst, lev, rec);
643 		if (dp != NULL)
644 			return(dp);
645 		m->pmatch[i].rm_so = offsave;
646 		return(NULL);
647 		break;
648 	case ORPAREN:		/* must undo assignment if rest fails */
649 		i = OPND(s);
650 		assert(0 < i && i <= m->g->nsub);
651 		offsave = m->pmatch[i].rm_eo;
652 		m->pmatch[i].rm_eo = sp - m->offp;
653 		dp = backref(m, sp, stop, ss+1, stopst, lev, rec);
654 		if (dp != NULL)
655 			return(dp);
656 		m->pmatch[i].rm_eo = offsave;
657 		return(NULL);
658 		break;
659 	default:		/* uh oh */
660 		assert(nope);
661 		break;
662 	}
663 
664 	/* "can't happen" */
665 	assert(nope);
666 	/* NOTREACHED */
667 	return 0;
668 }
669 
670 /*
671  - fast - step through the string at top speed
672  */
673 static char *			/* where tentative match ended, or NULL */
fast(struct match * m,char * start,char * stop,sopno startst,sopno stopst)674 fast(struct match *m, char *start, char *stop, sopno startst, sopno stopst)
675 {
676 	states st = m->st;
677 	states fresh = m->fresh;
678 	states tmp = m->tmp;
679 	char *p = start;
680 	int c = (start == m->beginp) ? OUT : *(start-1);
681 	int lastc;	/* previous c */
682 	int flagch;
683 	int i;
684 	char *coldp;	/* last p after which no match was underway */
685 
686 	CLEAR(st);
687 	SET1(st, startst);
688 	st = step(m->g, startst, stopst, st, NOTHING, st);
689 	ASSIGN(fresh, st);
690 	SP("start", st, *p);
691 	coldp = NULL;
692 	for (;;) {
693 		/* next character */
694 		lastc = c;
695 		c = (p == m->endp) ? OUT : *p;
696 		if (EQ(st, fresh))
697 			coldp = p;
698 
699 		/* is there an EOL and/or BOL between lastc and c? */
700 		flagch = '\0';
701 		i = 0;
702 		if ( (lastc == '\n' && m->g->cflags&REG_NEWLINE) ||
703 				(lastc == OUT && !(m->eflags&REG_NOTBOL)) ) {
704 			flagch = BOL;
705 			i = m->g->nbol;
706 		}
707 		if ( (c == '\n' && m->g->cflags&REG_NEWLINE) ||
708 				(c == OUT && !(m->eflags&REG_NOTEOL)) ) {
709 			flagch = (flagch == BOL) ? BOLEOL : EOL;
710 			i += m->g->neol;
711 		}
712 		if (i != 0) {
713 			for (; i > 0; i--)
714 				st = step(m->g, startst, stopst, st, flagch, st);
715 			SP("boleol", st, c);
716 		}
717 
718 		/* how about a word boundary? */
719 		if ( (flagch == BOL || (lastc != OUT && !ISWORD(lastc))) &&
720 					(c != OUT && ISWORD(c)) ) {
721 			flagch = BOW;
722 		}
723 		if ( (lastc != OUT && ISWORD(lastc)) &&
724 				(flagch == EOL || (c != OUT && !ISWORD(c))) ) {
725 			flagch = EOW;
726 		}
727 		if (flagch == BOW || flagch == EOW) {
728 			st = step(m->g, startst, stopst, st, flagch, st);
729 			SP("boweow", st, c);
730 		}
731 
732 		/* are we done? */
733 		if (ISSET(st, stopst) || p == stop)
734 			break;		/* NOTE BREAK OUT */
735 
736 		/* no, we must deal with this character */
737 		ASSIGN(tmp, st);
738 		ASSIGN(st, fresh);
739 		assert(c != OUT);
740 		st = step(m->g, startst, stopst, tmp, c, st);
741 		SP("aft", st, c);
742 		assert(EQ(step(m->g, startst, stopst, st, NOTHING, st), st));
743 		p++;
744 	}
745 
746 	assert(coldp != NULL);
747 	m->coldp = coldp;
748 	if (ISSET(st, stopst))
749 		return(p+1);
750 	else
751 		return(NULL);
752 }
753 
754 /*
755  - slow - step through the string more deliberately
756  */
757 static char *			/* where it ended */
slow(struct match * m,char * start,char * stop,sopno startst,sopno stopst)758 slow(struct match *m, char *start, char *stop, sopno startst, sopno stopst)
759 {
760 	states st = m->st;
761 	states empty = m->empty;
762 	states tmp = m->tmp;
763 	char *p = start;
764 	int c = (start == m->beginp) ? OUT : *(start-1);
765 	int lastc;	/* previous c */
766 	int flagch;
767 	int i;
768 	char *matchp;	/* last p at which a match ended */
769 
770 	AT("slow", start, stop, startst, stopst);
771 	CLEAR(st);
772 	SET1(st, startst);
773 	SP("sstart", st, *p);
774 	st = step(m->g, startst, stopst, st, NOTHING, st);
775 	matchp = NULL;
776 	for (;;) {
777 		/* next character */
778 		lastc = c;
779 		c = (p == m->endp) ? OUT : *p;
780 
781 		/* is there an EOL and/or BOL between lastc and c? */
782 		flagch = '\0';
783 		i = 0;
784 		if ( (lastc == '\n' && m->g->cflags&REG_NEWLINE) ||
785 				(lastc == OUT && !(m->eflags&REG_NOTBOL)) ) {
786 			flagch = BOL;
787 			i = m->g->nbol;
788 		}
789 		if ( (c == '\n' && m->g->cflags&REG_NEWLINE) ||
790 				(c == OUT && !(m->eflags&REG_NOTEOL)) ) {
791 			flagch = (flagch == BOL) ? BOLEOL : EOL;
792 			i += m->g->neol;
793 		}
794 		if (i != 0) {
795 			for (; i > 0; i--)
796 				st = step(m->g, startst, stopst, st, flagch, st);
797 			SP("sboleol", st, c);
798 		}
799 
800 		/* how about a word boundary? */
801 		if ( (flagch == BOL || (lastc != OUT && !ISWORD(lastc))) &&
802 					(c != OUT && ISWORD(c)) ) {
803 			flagch = BOW;
804 		}
805 		if ( (lastc != OUT && ISWORD(lastc)) &&
806 				(flagch == EOL || (c != OUT && !ISWORD(c))) ) {
807 			flagch = EOW;
808 		}
809 		if (flagch == BOW || flagch == EOW) {
810 			st = step(m->g, startst, stopst, st, flagch, st);
811 			SP("sboweow", st, c);
812 		}
813 
814 		/* are we done? */
815 		if (ISSET(st, stopst))
816 			matchp = p;
817 		if (EQ(st, empty) || p == stop)
818 			break;		/* NOTE BREAK OUT */
819 
820 		/* no, we must deal with this character */
821 		ASSIGN(tmp, st);
822 		ASSIGN(st, empty);
823 		assert(c != OUT);
824 		st = step(m->g, startst, stopst, tmp, c, st);
825 		SP("saft", st, c);
826 		assert(EQ(step(m->g, startst, stopst, st, NOTHING, st), st));
827 		p++;
828 	}
829 
830 	return(matchp);
831 }
832 
833 
834 /*
835  - step - map set of states reachable before char to set reachable after
836  */
837 static states
step(struct re_guts * g,sopno start,sopno stop,states bef,int ch,states aft)838 step(struct re_guts *g,
839     sopno start,		/* start state within strip */
840     sopno stop,			/* state after stop state within strip */
841     states bef,			/* states reachable before */
842     int ch,			/* character or NONCHAR code */
843     states aft)			/* states already known reachable after */
844 {
845 	cset *cs;
846 	sop s;
847 	sopno pc;
848 	onestate here;		/* note, macros know this name */
849 	sopno look;
850 	int i;
851 
852 	for (pc = start, INIT(here, pc); pc != stop; pc++, INC(here)) {
853 		s = g->strip[pc];
854 		switch (OP(s)) {
855 		case OEND:
856 			assert(pc == stop-1);
857 			break;
858 		case OCHAR:
859 			/* only characters can match */
860 			assert(!NONCHAR(ch) || ch != (char)OPND(s));
861 			if (ch == (char)OPND(s))
862 				FWD(aft, bef, 1);
863 			break;
864 		case OBOL:
865 			if (ch == BOL || ch == BOLEOL)
866 				FWD(aft, bef, 1);
867 			break;
868 		case OEOL:
869 			if (ch == EOL || ch == BOLEOL)
870 				FWD(aft, bef, 1);
871 			break;
872 		case OBOW:
873 			if (ch == BOW)
874 				FWD(aft, bef, 1);
875 			break;
876 		case OEOW:
877 			if (ch == EOW)
878 				FWD(aft, bef, 1);
879 			break;
880 		case OANY:
881 			if (!NONCHAR(ch))
882 				FWD(aft, bef, 1);
883 			break;
884 		case OANYOF:
885 			cs = &g->sets[OPND(s)];
886 			if (!NONCHAR(ch) && CHIN(cs, ch))
887 				FWD(aft, bef, 1);
888 			break;
889 		case OBACK_:		/* ignored here */
890 		case O_BACK:
891 			FWD(aft, aft, 1);
892 			break;
893 		case OPLUS_:		/* forward, this is just an empty */
894 			FWD(aft, aft, 1);
895 			break;
896 		case O_PLUS:		/* both forward and back */
897 			FWD(aft, aft, 1);
898 			i = ISSETBACK(aft, OPND(s));
899 			BACK(aft, aft, OPND(s));
900 			if (!i && ISSETBACK(aft, OPND(s))) {
901 				/* oho, must reconsider loop body */
902 				pc -= OPND(s) + 1;
903 				INIT(here, pc);
904 			}
905 			break;
906 		case OQUEST_:		/* two branches, both forward */
907 			FWD(aft, aft, 1);
908 			FWD(aft, aft, OPND(s));
909 			break;
910 		case O_QUEST:		/* just an empty */
911 			FWD(aft, aft, 1);
912 			break;
913 		case OLPAREN:		/* not significant here */
914 		case ORPAREN:
915 			FWD(aft, aft, 1);
916 			break;
917 		case OCH_:		/* mark the first two branches */
918 			FWD(aft, aft, 1);
919 			assert(OP(g->strip[pc+OPND(s)]) == OOR2);
920 			FWD(aft, aft, OPND(s));
921 			break;
922 		case OOR1:		/* done a branch, find the O_CH */
923 			if (ISSTATEIN(aft, here)) {
924 				for (look = 1;
925 						OP(s = g->strip[pc+look]) != O_CH;
926 						look += OPND(s))
927 					assert(OP(s) == OOR2);
928 				FWD(aft, aft, look);
929 			}
930 			break;
931 		case OOR2:		/* propagate OCH_'s marking */
932 			FWD(aft, aft, 1);
933 			if (OP(g->strip[pc+OPND(s)]) != O_CH) {
934 				assert(OP(g->strip[pc+OPND(s)]) == OOR2);
935 				FWD(aft, aft, OPND(s));
936 			}
937 			break;
938 		case O_CH:		/* just empty */
939 			FWD(aft, aft, 1);
940 			break;
941 		default:		/* ooooops... */
942 			assert(nope);
943 			break;
944 		}
945 	}
946 
947 	return(aft);
948 }
949 
950 #ifdef REDEBUG
951 /*
952  - print - print a set of states
953  */
954 static void
print(struct match * m,char * caption,states st,int ch,FILE * d)955 print(struct match *m, char *caption, states st, int ch, FILE *d)
956 {
957 	struct re_guts *g = m->g;
958 	int i;
959 	int first = 1;
960 
961 	if (!(m->eflags&REG_TRACE))
962 		return;
963 
964 	(void)fprintf(d, "%s", caption);
965 	if (ch != '\0')
966 		(void)fprintf(d, " %s", pchar(ch));
967 	for (i = 0; i < g->nstates; i++)
968 		if (ISSET(st, i)) {
969 			(void)fprintf(d, "%s%d", (first) ? "\t" : ", ", i);
970 			first = 0;
971 		}
972 	(void)fprintf(d, "\n");
973 }
974 
975 /*
976  - at - print current situation
977  */
978 static void
at(struct match * m,char * title,char * start,char * stop,sopno startst,sopno stopst)979 at(struct match *m, char *title, char *start, char *stop, sopno startst,
980     sopno stopst)
981 {
982 	if (!(m->eflags&REG_TRACE))
983 		return;
984 
985 	(void)printf("%s %s-", title, pchar(*start));
986 	(void)printf("%s ", pchar(*stop));
987 	(void)printf("%ld-%ld\n", (long)startst, (long)stopst);
988 }
989 
990 #ifndef PCHARDONE
991 #define	PCHARDONE	/* never again */
992 /*
993  - pchar - make a character printable
994  *
995  * Is this identical to regchar() over in debug.c?  Well, yes.  But a
996  * duplicate here avoids having a debugging-capable regexec.o tied to
997  * a matching debug.o, and this is convenient.  It all disappears in
998  * the non-debug compilation anyway, so it doesn't matter much.
999  */
1000 static char *			/* -> representation */
pchar(int ch)1001 pchar(int ch)
1002 {
1003 	static char pbuf[10];
1004 
1005 	if (isprint(ch) || ch == ' ')
1006 		(void)_snprintf(pbuf, sizeof pbuf, "%c", ch);
1007 	else
1008 		(void)_snprintf(pbuf, sizeof pbuf, "\\%o", ch);
1009 	return(pbuf);
1010 }
1011 #endif
1012 #endif
1013 
1014 #undef	matcher
1015 #undef	fast
1016 #undef	slow
1017 #undef	dissect
1018 #undef	backref
1019 #undef	step
1020 #undef	print
1021 #undef	at
1022 #undef	match
1023 #undef	nope
1024