1 /*-
2  * This code is derived from OpenBSD's libc/regex, original license follows:
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 	size_t 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 = 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 *)cli_malloc((m->g->nsub + 1) *
207 							sizeof(regmatch_t));
208 		if (m->pmatch == NULL) {
209 			free(m->lastpos);
210 			STATETEARDOWN(m);
211 			return(REG_ESPACE);
212 		}
213 		for (i = 1; i <= m->g->nsub; i++)
214 			m->pmatch[i].rm_so = m->pmatch[i].rm_eo = -1;
215 		if (!g->backrefs && !(m->eflags&REG_BACKR)) {
216 			NOTE("dissecting");
217 			dp = dissect(m, m->coldp, endp, gf, gl);
218 		} else {
219 			if (g->nplus > 0 && m->lastpos == NULL)
220 				m->lastpos = (char **)cli_malloc((g->nplus+1) *
221 							sizeof(char *));
222 			if (g->nplus > 0 && m->lastpos == NULL) {
223 				free(m->pmatch);
224 				STATETEARDOWN(m);
225 				return(REG_ESPACE);
226 			}
227 			NOTE("backref dissect");
228 			dp = backref(m, m->coldp, endp, gf, gl, (sopno)0, 0);
229 		}
230 		if (dp != NULL)
231 			break;
232 
233 		/* uh-oh... we couldn't find a subexpression-level match */
234 		assert(g->backrefs);	/* must be back references doing it */
235 		assert(g->nplus == 0 || m->lastpos != NULL);
236 		for (;;) {
237 			if (dp != NULL || endp <= m->coldp)
238 				break;		/* defeat */
239 			NOTE("backoff");
240 			endp = slow(m, m->coldp, endp-1, gf, gl);
241 			if (endp == NULL)
242 				break;		/* defeat */
243 			/* try it on a shorter possibility */
244 #ifndef NDEBUG
245 			for (i = 1; i <= m->g->nsub; i++) {
246 				assert(m->pmatch[i].rm_so == -1);
247 				assert(m->pmatch[i].rm_eo == -1);
248 			}
249 #endif
250 			NOTE("backoff dissect");
251 			dp = backref(m, m->coldp, endp, gf, gl, (sopno)0, 0);
252 		}
253 		assert(dp == NULL || dp == endp);
254 		if (dp != NULL)		/* found a shorter one */
255 			break;
256 
257 		/* despite initial appearances, there is no match here */
258 		NOTE("false alarm");
259 		if (m->coldp == stop)
260 			break;
261 		start = m->coldp + 1;	/* recycle starting later */
262 	}
263 
264 	/* fill in the details if requested */
265 	if (nmatch > 0) {
266 		pmatch[0].rm_so = m->coldp - m->offp;
267 		pmatch[0].rm_eo = endp - m->offp;
268 	}
269 	if (nmatch > 1) {
270 		assert(m->pmatch != NULL);
271 		for (i = 1; i < nmatch; i++)
272 			if (i <= m->g->nsub)
273 				pmatch[i] = m->pmatch[i];
274 			else {
275 				pmatch[i].rm_so = -1;
276 				pmatch[i].rm_eo = -1;
277 			}
278 	}
279 
280 	if (m->pmatch != NULL)
281 		free((char *)m->pmatch);
282 	if (m->lastpos != NULL)
283 		free((char *)m->lastpos);
284 	STATETEARDOWN(m);
285 	return(0);
286 }
287 
288 /*
289  - dissect - figure out what matched what, no back references
290  */
291 static char *			/* == stop (success) always */
dissect(struct match * m,char * start,char * stop,sopno startst,sopno stopst)292 dissect(struct match *m, char *start, char *stop, sopno startst, sopno stopst)
293 {
294 	int i;
295 	sopno ss;	/* start sop of current subRE */
296 	sopno es;	/* end sop of current subRE */
297 	char *sp;	/* start of string matched by it */
298 	char *stp;	/* string matched by it cannot pass here */
299 	char *rest;	/* start of rest of string */
300 	char *tail;	/* string unmatched by rest of RE */
301 	sopno ssub;	/* start sop of subsubRE */
302 	sopno esub;	/* end sop of subsubRE */
303 	char *ssp;	/* start of string matched by subsubRE */
304 	char *sep;	/* end of string matched by subsubRE */
305 	char *oldssp;	/* previous ssp */
306 	char *dp;
307 
308 	AT("diss", start, stop, startst, stopst);
309 	sp = start;
310 	for (ss = startst; ss < stopst; ss = es) {
311 		/* identify end of subRE */
312 		es = ss;
313 		switch (OP(m->g->strip[es])) {
314 		case OPLUS_:
315 		case OQUEST_:
316 			es += OPND(m->g->strip[es]);
317 			break;
318 		case OCH_:
319 			while (OP(m->g->strip[es]) != O_CH)
320 				es += OPND(m->g->strip[es]);
321 			break;
322 		}
323 		es++;
324 
325 		/* figure out what it matched */
326 		switch (OP(m->g->strip[ss])) {
327 		case OEND:
328 			assert(nope);
329 			break;
330 		case OCHAR:
331 			sp++;
332 			break;
333 		case OBOL:
334 		case OEOL:
335 		case OBOW:
336 		case OEOW:
337 			break;
338 		case OANY:
339 		case OANYOF:
340 			sp++;
341 			break;
342 		case OBACK_:
343 		case O_BACK:
344 			assert(nope);
345 			break;
346 		/* cases where length of match is hard to find */
347 		case OQUEST_:
348 			stp = stop;
349 			for (;;) {
350 				/* how long could this one be? */
351 				rest = slow(m, sp, stp, ss, es);
352 				assert(rest != NULL);	/* it did match */
353 				/* could the rest match the rest? */
354 				tail = slow(m, rest, stop, es, stopst);
355 				if (tail == stop)
356 					break;		/* yes! */
357 				/* no -- try a shorter match for this one */
358 				stp = rest - 1;
359 				assert(stp >= sp);	/* it did work */
360 			}
361 			ssub = ss + 1;
362 			esub = es - 1;
363 			/* did innards match? */
364 			if (slow(m, sp, rest, ssub, esub) != NULL) {
365 				dp = dissect(m, sp, rest, ssub, esub);
366 				assert(dp == rest);
367 			} else		/* no */
368 				assert(sp == rest);
369 			sp = rest;
370 			break;
371 		case OPLUS_:
372 			stp = stop;
373 			for (;;) {
374 				/* how long could this one be? */
375 				rest = slow(m, sp, stp, ss, es);
376 				assert(rest != NULL);	/* it did match */
377 				/* could the rest match the rest? */
378 				tail = slow(m, rest, stop, es, stopst);
379 				if (tail == stop)
380 					break;		/* yes! */
381 				/* no -- try a shorter match for this one */
382 				stp = rest - 1;
383 				assert(stp >= sp);	/* it did work */
384 			}
385 			ssub = ss + 1;
386 			esub = es - 1;
387 			ssp = sp;
388 			oldssp = ssp;
389 			for (;;) {	/* find last match of innards */
390 				sep = slow(m, ssp, rest, ssub, esub);
391 				if (sep == NULL || sep == ssp)
392 					break;	/* failed or matched null */
393 				oldssp = ssp;	/* on to next try */
394 				ssp = sep;
395 			}
396 			if (sep == NULL) {
397 				/* last successful match */
398 				sep = ssp;
399 				ssp = oldssp;
400 			}
401 			assert(sep == rest);	/* must exhaust substring */
402 			assert(slow(m, ssp, sep, ssub, esub) == rest);
403 			dp = dissect(m, ssp, sep, ssub, esub);
404 			assert(dp == sep);
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 			dp = dissect(m, sp, rest, ssub, esub);
439 			assert(dp == rest);
440 			sp = rest;
441 			break;
442 		case O_PLUS:
443 		case O_QUEST:
444 		case OOR1:
445 		case OOR2:
446 		case O_CH:
447 			assert(nope);
448 			break;
449 		case OLPAREN:
450 			i = OPND(m->g->strip[ss]);
451 			assert(0 < i && (size_t)i <= m->g->nsub);
452 			m->pmatch[i].rm_so = sp - m->offp;
453 			break;
454 		case ORPAREN:
455 			i = OPND(m->g->strip[ss]);
456 			assert(0 < i && (size_t)i <= m->g->nsub);
457 			m->pmatch[i].rm_eo = sp - m->offp;
458 			break;
459 		default:		/* uh oh */
460 			assert(nope);
461 			break;
462 		}
463 	}
464 
465 	assert(sp == stop);
466 	return(sp);
467 }
468 
469 /*
470  - backref - figure out what matched what, figuring in back references
471  */
472 static char *			/* == stop (success) or NULL (failure) */
backref(struct match * m,char * start,char * stop,sopno startst,sopno stopst,sopno lev,int rec)473 backref(struct match *m, char *start, char *stop, sopno startst, sopno stopst,
474     sopno lev, int rec)			/* PLUS nesting level */
475 {
476 	int i;
477 	sopno ss;	/* start sop of current subRE */
478 	char *sp;	/* start of string matched by it */
479 	sopno ssub;	/* start sop of subsubRE */
480 	sopno esub;	/* end sop of subsubRE */
481 	char *ssp;	/* start of string matched by subsubRE */
482 	char *dp;
483 	size_t len;
484 	int hard;
485 	sop s;
486 	regoff_t offsave;
487 	cset *cs;
488 
489 	AT("back", start, stop, startst, stopst);
490 	sp = start;
491 
492 	/* get as far as we can with easy stuff */
493 	hard = 0;
494 	for (ss = startst; !hard && ss < stopst; ss++)
495 		switch (OP(s = m->g->strip[ss])) {
496 		case OCHAR:
497 			if (sp == stop || *sp++ != (char)OPND(s))
498 				return(NULL);
499 			break;
500 		case OANY:
501 			if (sp == stop)
502 				return(NULL);
503 			sp++;
504 			break;
505 		case OANYOF:
506 			cs = &m->g->sets[OPND(s)];
507 			if (sp == stop || !CHIN(cs, *sp++))
508 				return(NULL);
509 			break;
510 		case OBOL:
511 			if ( (sp == m->beginp && !(m->eflags&REG_NOTBOL)) ||
512 					(sp < m->endp && *(sp-1) == '\n' &&
513 						(m->g->cflags&REG_NEWLINE)) )
514 				{ /* yes */ }
515 			else
516 				return(NULL);
517 			break;
518 		case OEOL:
519 			if ( (sp == m->endp && !(m->eflags&REG_NOTEOL)) ||
520 					(sp < m->endp && *sp == '\n' &&
521 						(m->g->cflags&REG_NEWLINE)) )
522 				{ /* yes */ }
523 			else
524 				return(NULL);
525 			break;
526 		case OBOW:
527 			if (( (sp == m->beginp && !(m->eflags&REG_NOTBOL)) ||
528 					(sp < m->endp && *(sp-1) == '\n' &&
529 						(m->g->cflags&REG_NEWLINE)) ||
530 					(sp > m->beginp &&
531 							!ISWORD(*(sp-1))) ) &&
532 					(sp < m->endp && ISWORD(*sp)) )
533 				{ /* yes */ }
534 			else
535 				return(NULL);
536 			break;
537 		case OEOW:
538 			if (( (sp == m->endp && !(m->eflags&REG_NOTEOL)) ||
539 					(sp < m->endp && *sp == '\n' &&
540 						(m->g->cflags&REG_NEWLINE)) ||
541 					(sp < m->endp && !ISWORD(*sp)) ) &&
542 					(sp > m->beginp && ISWORD(*(sp-1))) )
543 				{ /* yes */ }
544 			else
545 				return(NULL);
546 			break;
547 		case O_QUEST:
548 			break;
549 		case OOR1:	/* matches null but needs to skip */
550 			ss++;
551 			s = m->g->strip[ss];
552 			do {
553 				assert(OP(s) == OOR2);
554 				ss += OPND(s);
555 			} while (OP(s = m->g->strip[ss]) != O_CH);
556 			/* note that the ss++ gets us past the O_CH */
557 			break;
558 		default:	/* have to make a choice */
559 			hard = 1;
560 			break;
561 		}
562 	if (!hard) {		/* that was it! */
563 		if (sp != stop)
564 			return(NULL);
565 		return(sp);
566 	}
567 	ss--;			/* adjust for the for's final increment */
568 
569 	/* the hard stuff */
570 	AT("hard", sp, stop, ss, stopst);
571 	s = m->g->strip[ss];
572 	switch (OP(s)) {
573 	case OBACK_:		/* the vilest depths */
574 		i = OPND(s);
575 		assert(0 < i && (size_t)i <= m->g->nsub);
576 		if (m->pmatch[i].rm_eo == -1)
577 			return(NULL);
578 		assert(m->pmatch[i].rm_so != -1);
579 		len = m->pmatch[i].rm_eo - m->pmatch[i].rm_so;
580 		if (len == 0 && rec++ > MAX_RECURSION)
581 			return(NULL);
582 		assert((size_t)(stop - m->beginp) >= len);
583 		if (sp > stop - len)
584 			return(NULL);	/* not enough left to match */
585 		ssp = m->offp + m->pmatch[i].rm_so;
586 		if (memcmp(sp, ssp, len) != 0)
587 			return(NULL);
588 		while (m->g->strip[ss] != SOP(O_BACK, i))
589 			ss++;
590 		return(backref(m, sp+len, stop, ss+1, stopst, lev, rec));
591 		break;
592 	case OQUEST_:		/* to null or not */
593 		dp = backref(m, sp, stop, ss+1, stopst, lev, rec);
594 		if (dp != NULL)
595 			return(dp);	/* not */
596 		return(backref(m, sp, stop, ss+OPND(s)+1, stopst, lev, rec));
597 		break;
598 	case OPLUS_:
599 		assert(m->lastpos != NULL);
600 		assert(lev+1 <= m->g->nplus);
601 		m->lastpos[lev+1] = sp;
602 		return(backref(m, sp, stop, ss+1, stopst, lev+1, rec));
603 		break;
604 	case O_PLUS:
605 		if (sp == m->lastpos[lev])	/* last pass matched null */
606 			return(backref(m, sp, stop, ss+1, stopst, lev-1, rec));
607 		/* try another pass */
608 		m->lastpos[lev] = sp;
609 		dp = backref(m, sp, stop, ss-OPND(s)+1, stopst, lev, rec);
610 		if (dp == NULL)
611 			return(backref(m, sp, stop, ss+1, stopst, lev-1, rec));
612 		else
613 			return(dp);
614 		break;
615 	case OCH_:		/* find the right one, if any */
616 		ssub = ss + 1;
617 		esub = ss + OPND(s) - 1;
618 		assert(OP(m->g->strip[esub]) == OOR1);
619 		for (;;) {	/* find first matching branch */
620 			dp = backref(m, sp, stop, ssub, esub, lev, rec);
621 			if (dp != NULL)
622 				return(dp);
623 			/* that one missed, try next one */
624 			if (OP(m->g->strip[esub]) == O_CH)
625 				return(NULL);	/* there is none */
626 			esub++;
627 			assert(OP(m->g->strip[esub]) == OOR2);
628 			ssub = esub + 1;
629 			esub += OPND(m->g->strip[esub]);
630 			if (OP(m->g->strip[esub]) == OOR2)
631 				esub--;
632 			else
633 				assert(OP(m->g->strip[esub]) == O_CH);
634 		}
635 		break;
636 	case OLPAREN:		/* must undo assignment if rest fails */
637 		i = OPND(s);
638 		assert(0 < i && (size_t)i <= m->g->nsub);
639 		offsave = m->pmatch[i].rm_so;
640 		m->pmatch[i].rm_so = sp - m->offp;
641 		dp = backref(m, sp, stop, ss+1, stopst, lev, rec);
642 		if (dp != NULL)
643 			return(dp);
644 		m->pmatch[i].rm_so = offsave;
645 		return(NULL);
646 		break;
647 	case ORPAREN:		/* must undo assignment if rest fails */
648 		i = OPND(s);
649 		assert(0 < i && (size_t)i <= m->g->nsub);
650 		offsave = m->pmatch[i].rm_eo;
651 		m->pmatch[i].rm_eo = sp - m->offp;
652 		dp = backref(m, sp, stop, ss+1, stopst, lev, rec);
653 		if (dp != NULL)
654 			return(dp);
655 		m->pmatch[i].rm_eo = offsave;
656 		return(NULL);
657 		break;
658 	default:		/* uh oh */
659 		assert(nope);
660 		break;
661 	}
662 
663 	/* "can't happen" */
664 	assert(nope);
665 	/* NOTREACHED */
666 	return(NULL);
667 }
668 
669 /*
670  - fast - step through the string at top speed
671  */
672 static char *			/* where tentative match ended, or NULL */
fast(struct match * m,char * start,char * stop,sopno startst,sopno stopst)673 fast(struct match *m, char *start, char *stop, sopno startst, sopno stopst)
674 {
675 	states st = m->st;
676 	states fresh = m->fresh;
677 	states tmp = m->tmp;
678 	char *p = start;
679 	int c = (start == m->beginp) ? OUT : *(start-1);
680 	int lastc;	/* previous c */
681 	int flagch;
682 	int i;
683 	char *coldp;	/* last p after which no match was underway */
684 
685 	CLEAR(st);
686 	SET1(st, startst);
687 	st = step(m->g, startst, stopst, st, NOTHING, st);
688 	ASSIGN(fresh, st);
689 	SP("start", st, *p);
690 	coldp = NULL;
691 	for (;;) {
692 		/* next character */
693 		lastc = c;
694 		c = (p == m->endp) ? OUT : *p;
695 		if (EQ(st, fresh))
696 			coldp = p;
697 
698 		/* is there an EOL and/or BOL between lastc and c? */
699 		flagch = '\0';
700 		i = 0;
701 		if ( (lastc == '\n' && m->g->cflags&REG_NEWLINE) ||
702 				(lastc == OUT && !(m->eflags&REG_NOTBOL)) ) {
703 			flagch = BOL;
704 			i = m->g->nbol;
705 		}
706 		if ( (c == '\n' && m->g->cflags&REG_NEWLINE) ||
707 				(c == OUT && !(m->eflags&REG_NOTEOL)) ) {
708 			flagch = (flagch == BOL) ? BOLEOL : EOL;
709 			i += m->g->neol;
710 		}
711 		if (i != 0) {
712 			for (; i > 0; i--)
713 				st = step(m->g, startst, stopst, st, flagch, st);
714 			SP("boleol", st, c);
715 		}
716 
717 		/* how about a word boundary? */
718 		if ( (flagch == BOL || (lastc != OUT && !ISWORD(lastc))) &&
719 					(c != OUT && ISWORD(c)) ) {
720 			flagch = BOW;
721 		}
722 		if ( (lastc != OUT && ISWORD(lastc)) &&
723 				(flagch == EOL || (c != OUT && !ISWORD(c))) ) {
724 			flagch = EOW;
725 		}
726 		if (flagch == BOW || flagch == EOW) {
727 			st = step(m->g, startst, stopst, st, flagch, st);
728 			SP("boweow", st, c);
729 		}
730 
731 		/* are we done? */
732 		if (ISSET(st, stopst) || p == stop)
733 			break;		/* NOTE BREAK OUT */
734 
735 		/* no, we must deal with this character */
736 		ASSIGN(tmp, st);
737 		ASSIGN(st, fresh);
738 		assert(c != OUT);
739 		st = step(m->g, startst, stopst, tmp, c, st);
740 		SP("aft", st, c);
741 		assert(EQ(step(m->g, startst, stopst, st, NOTHING, st), st));
742 		p++;
743 	}
744 
745 	assert(coldp != NULL);
746 	m->coldp = coldp;
747 	if (ISSET(st, stopst))
748 		return(p+1);
749 	else
750 		return(NULL);
751 }
752 
753 /*
754  - slow - step through the string more deliberately
755  */
756 static char *			/* where it ended */
slow(struct match * m,char * start,char * stop,sopno startst,sopno stopst)757 slow(struct match *m, char *start, char *stop, sopno startst, sopno stopst)
758 {
759 	states st = m->st;
760 	states empty = m->empty;
761 	states tmp = m->tmp;
762 	char *p = start;
763 	int c = (start == m->beginp) ? OUT : *(start-1);
764 	int lastc;	/* previous c */
765 	int flagch;
766 	int i;
767 	char *matchp;	/* last p at which a match ended */
768 
769 	AT("slow", start, stop, startst, stopst);
770 	CLEAR(st);
771 	SET1(st, startst);
772 	SP("sstart", st, *p);
773 	st = step(m->g, startst, stopst, st, NOTHING, st);
774 	matchp = NULL;
775 	for (;;) {
776 		/* next character */
777 		lastc = c;
778 		c = (p == m->endp) ? OUT : *p;
779 
780 		/* is there an EOL and/or BOL between lastc and c? */
781 		flagch = '\0';
782 		i = 0;
783 		if ( (lastc == '\n' && m->g->cflags&REG_NEWLINE) ||
784 				(lastc == OUT && !(m->eflags&REG_NOTBOL)) ) {
785 			flagch = BOL;
786 			i = m->g->nbol;
787 		}
788 		if ( (c == '\n' && m->g->cflags&REG_NEWLINE) ||
789 				(c == OUT && !(m->eflags&REG_NOTEOL)) ) {
790 			flagch = (flagch == BOL) ? BOLEOL : EOL;
791 			i += m->g->neol;
792 		}
793 		if (i != 0) {
794 			for (; i > 0; i--)
795 				st = step(m->g, startst, stopst, st, flagch, st);
796 			SP("sboleol", st, c);
797 		}
798 
799 		/* how about a word boundary? */
800 		if ( (flagch == BOL || (lastc != OUT && !ISWORD(lastc))) &&
801 					(c != OUT && ISWORD(c)) ) {
802 			flagch = BOW;
803 		}
804 		if ( (lastc != OUT && ISWORD(lastc)) &&
805 				(flagch == EOL || (c != OUT && !ISWORD(c))) ) {
806 			flagch = EOW;
807 		}
808 		if (flagch == BOW || flagch == EOW) {
809 			st = step(m->g, startst, stopst, st, flagch, st);
810 			SP("sboweow", st, c);
811 		}
812 
813 		/* are we done? */
814 		if (ISSET(st, stopst))
815 			matchp = p;
816 		if (EQ(st, empty) || p == stop)
817 			break;		/* NOTE BREAK OUT */
818 
819 		/* no, we must deal with this character */
820 		ASSIGN(tmp, st);
821 		ASSIGN(st, empty);
822 		assert(c != OUT);
823 		st = step(m->g, startst, stopst, tmp, c, st);
824 		SP("saft", st, c);
825 		assert(EQ(step(m->g, startst, stopst, st, NOTHING, st), st));
826 		p++;
827 	}
828 
829 	return(matchp);
830 }
831 
832 
833 /*
834  - step - map set of states reachable before char to set reachable after
835  */
836 static states
step(struct re_guts * g,sopno start,sopno stop,states bef,int ch,states aft)837 step(struct re_guts *g,
838     sopno start,		/* start state within strip */
839     sopno stop,			/* state after stop state within strip */
840     states bef,			/* states reachable before */
841     int ch,			/* character or NONCHAR code */
842     states aft)			/* states already known reachable after */
843 {
844 	cset *cs;
845 	sop s;
846 	sopno pc;
847 	onestate here;		/* note, macros know this name */
848 	sopno look;
849 	int i;
850 
851 	for (pc = start, INIT(here, pc); pc != stop; pc++, INC(here)) {
852 		s = g->strip[pc];
853 		switch (OP(s)) {
854 		case OEND:
855 			assert(pc == stop-1);
856 			break;
857 		case OCHAR:
858 			/* only characters can match */
859 			assert(!NONCHAR(ch) || ch != (char)OPND(s));
860 			if (ch == (char)OPND(s))
861 				FWD(aft, bef, 1);
862 			break;
863 		case OBOL:
864 			if (ch == BOL || ch == BOLEOL)
865 				FWD(aft, bef, 1);
866 			break;
867 		case OEOL:
868 			if (ch == EOL || ch == BOLEOL)
869 				FWD(aft, bef, 1);
870 			break;
871 		case OBOW:
872 			if (ch == BOW)
873 				FWD(aft, bef, 1);
874 			break;
875 		case OEOW:
876 			if (ch == EOW)
877 				FWD(aft, bef, 1);
878 			break;
879 		case OANY:
880 			if (!NONCHAR(ch))
881 				FWD(aft, bef, 1);
882 			break;
883 		case OANYOF:
884 			cs = &g->sets[OPND(s)];
885 			if (!NONCHAR(ch) && CHIN(cs, ch))
886 				FWD(aft, bef, 1);
887 			break;
888 		case OBACK_:		/* ignored here */
889 		case O_BACK:
890 			FWD(aft, aft, 1);
891 			break;
892 		case OPLUS_:		/* forward, this is just an empty */
893 			FWD(aft, aft, 1);
894 			break;
895 		case O_PLUS:		/* both forward and back */
896 			FWD(aft, aft, 1);
897 			i = ISSETBACK(aft, OPND(s));
898 			BACK(aft, aft, OPND(s));
899 			if (!i && ISSETBACK(aft, OPND(s))) {
900 				/* oho, must reconsider loop body */
901 				pc -= OPND(s) + 1;
902 				INIT(here, pc);
903 			}
904 			break;
905 		case OQUEST_:		/* two branches, both forward */
906 			FWD(aft, aft, 1);
907 			FWD(aft, aft, OPND(s));
908 			break;
909 		case O_QUEST:		/* just an empty */
910 			FWD(aft, aft, 1);
911 			break;
912 		case OLPAREN:		/* not significant here */
913 		case ORPAREN:
914 			FWD(aft, aft, 1);
915 			break;
916 		case OCH_:		/* mark the first two branches */
917 			FWD(aft, aft, 1);
918 			assert(OP(g->strip[pc+OPND(s)]) == OOR2);
919 			FWD(aft, aft, OPND(s));
920 			break;
921 		case OOR1:		/* done a branch, find the O_CH */
922 			if (ISSTATEIN(aft, here)) {
923 				for (look = 1;
924 						OP(s = g->strip[pc+look]) != O_CH;
925 						look += OPND(s))
926 					assert(OP(s) == OOR2);
927 				FWD(aft, aft, look);
928 			}
929 			break;
930 		case OOR2:		/* propagate OCH_'s marking */
931 			FWD(aft, aft, 1);
932 			if (OP(g->strip[pc+OPND(s)]) != O_CH) {
933 				assert(OP(g->strip[pc+OPND(s)]) == OOR2);
934 				FWD(aft, aft, OPND(s));
935 			}
936 			break;
937 		case O_CH:		/* just empty */
938 			FWD(aft, aft, 1);
939 			break;
940 		default:		/* ooooops... */
941 			assert(nope);
942 			break;
943 		}
944 	}
945 
946 	return(aft);
947 }
948 
949 #ifdef REDEBUG
950 /*
951  - print - print a set of states
952  */
953 static void
print(struct match * m,char * caption,states st,int ch,FILE * d)954 print(struct match *m, char *caption, states st, int ch, FILE *d)
955 {
956 	struct re_guts *g = m->g;
957 	int i;
958 	int first = 1;
959 
960 	if (!(m->eflags&REG_TRACE))
961 		return;
962 
963 	(void)fprintf(d, "%s", caption);
964 	if (ch != '\0')
965 		(void)fprintf(d, " %s", pchar(ch));
966 	for (i = 0; i < g->nstates; i++)
967 		if (ISSET(st, i)) {
968 			(void)fprintf(d, "%s%d", (first) ? "\t" : ", ", i);
969 			first = 0;
970 		}
971 	(void)fprintf(d, "\n");
972 }
973 
974 /*
975  - at - print current situation
976  */
977 static void
at(struct match * m,char * title,char * start,char * stop,sopno startst,sopno stopst)978 at(struct match *m, char *title, char *start, char *stop, sopno startst,
979     sopno stopst)
980 {
981 	if (!(m->eflags&REG_TRACE))
982 		return;
983 
984 	(void)printf("%s %s-", title, pchar(*start));
985 	(void)printf("%s ", pchar(*stop));
986 	(void)printf("%ld-%ld\n", (long)startst, (long)stopst);
987 }
988 
989 #ifndef PCHARDONE
990 #define	PCHARDONE	/* never again */
991 /*
992  - pchar - make a character printable
993  *
994  * Is this identical to regchar() over in debug.c?  Well, yes.  But a
995  * duplicate here avoids having a debugging-capable regexec.o tied to
996  * a matching debug.o, and this is convenient.  It all disappears in
997  * the non-debug compilation anyway, so it doesn't matter much.
998  */
999 static char *			/* -> representation */
pchar(int ch)1000 pchar(int ch)
1001 {
1002 	static char pbuf[10];
1003 
1004 	if (isprint(ch) || ch == ' ')
1005 		(void)snprintf(pbuf, sizeof pbuf, "%c", ch);
1006 	else
1007 		(void)snprintf(pbuf, sizeof pbuf, "\\%o", ch);
1008 	return(pbuf);
1009 }
1010 #endif
1011 #endif
1012 
1013 #undef	matcher
1014 #undef	fast
1015 #undef	slow
1016 #undef	dissect
1017 #undef	backref
1018 #undef	step
1019 #undef	print
1020 #undef	at
1021 #undef	match
1022 #undef	nope
1023