xref: /illumos-gate/usr/src/lib/libc/port/regex/engine.c (revision 14247eb6021ea270e0af749dc79eb5bec64631f2)
1 /*
2  * Copyright 2023 Bill Sommerfeld <sommerfeld@hamachi.org>
3  * Copyright 2019 Nexenta by DDN, Inc. All rights reserved.
4  * Copyright 2012 Milan Jurik. All rights reserved.
5  * Copyright (c) 2016 by Delphix. All rights reserved.
6  * Copyright (c) 1992, 1993, 1994 Henry Spencer.
7  * Copyright (c) 1992, 1993, 1994
8  *	The Regents of the University of California.  All rights reserved.
9  *
10  * This code is derived from software contributed to Berkeley by
11  * Henry Spencer.
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  * 1. Redistributions of source code must retain the above copyright
17  *    notice, this list of conditions and the following disclaimer.
18  * 2. Redistributions in binary form must reproduce the above copyright
19  *    notice, this list of conditions and the following disclaimer in the
20  *    documentation and/or other materials provided with the distribution.
21  * 3. Neither the name of the University nor the names of its contributors
22  *    may be used to endorse or promote products derived from this software
23  *    without specific prior written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35  * SUCH DAMAGE.
36  */
37 
38 #include <stdbool.h>
39 
40 /*
41  * The matching engine and friends.  This file is #included by regexec.c
42  * after suitable #defines of a variety of macros used herein, so that
43  * different state representations can be used without duplicating masses
44  * of code.
45  */
46 
47 #ifdef SNAMES
48 #define	stepback sstepback
49 #define	matcher	smatcher
50 #define	walk	swalk
51 #define	dissect	sdissect
52 #define	backref	sbackref
53 #define	step	sstep
54 #define	print	sprint
55 #define	at	sat
56 #define	match	smat
57 #endif
58 #ifdef LNAMES
59 #define	stepback lstepback
60 #define	matcher	lmatcher
61 #define	walk	lwalk
62 #define	dissect	ldissect
63 #define	backref	lbackref
64 #define	step	lstep
65 #define	print	lprint
66 #define	at	lat
67 #define	match	lmat
68 #endif
69 #ifdef MNAMES
70 #define	stepback mstepback
71 #define	matcher	mmatcher
72 #define	walk	mwalk
73 #define	dissect	mdissect
74 #define	backref	mbackref
75 #define	step	mstep
76 #define	print	mprint
77 #define	at	mat
78 #define	match	mmat
79 #endif
80 
81 /* another structure passed up and down to avoid zillions of parameters */
82 struct match {
83 	struct re_guts *g;
84 	int eflags;
85 	regmatch_t *pmatch;	/* [nsub+1] (0 element unused) */
86 	const char *offp;	/* offsets work from here */
87 	const char *beginp;	/* start of string -- virtual NUL precedes */
88 	const char *endp;	/* end of string -- virtual NUL here */
89 	const char *coldp;	/* can be no match starting before here */
90 	const char **lastpos;	/* [nplus+1] */
91 	STATEVARS;
92 	states st;		/* current states */
93 	states fresh;		/* states for a fresh start */
94 	states tmp;		/* temporary */
95 	states empty;		/* empty set of states */
96 	mbstate_t mbs;		/* multibyte conversion state */
97 };
98 
99 /* ========= begin header generated by ./mkh ========= */
100 #ifdef __cplusplus
101 extern "C" {
102 #endif
103 
104 /* === engine.c === */
105 static int matcher(struct re_guts *, const char *, size_t, regmatch_t[], int);
106 static const char *dissect(struct match *, const char *, const char *,
107     sopno, sopno);
108 static const char *backref(struct match *, const char *, const char *, sopno,
109     sopno, sopno, int);
110 static const char *walk(struct match *m, const char *start, const char *stop,
111     sopno startst, sopno stopst, bool fast);
112 static states step(struct re_guts *, sopno, sopno, states, wint_t, states);
113 #define	MAX_RECURSION	100
114 #define	BOL	(OUT-1)
115 #define	EOL	(BOL-1)
116 #define	BOLEOL	(BOL-2)
117 #define	NOTHING	(BOL-3)
118 #define	BOW	(BOL-4)
119 #define	EOW	(BOL-5)
120 #define	BADCHAR	(BOL-6)
121 #define	NONCHAR(c)	((c) <= OUT)
122 #ifdef REDEBUG
123 static void print(struct match *, const char *, states, int, FILE *);
124 #endif
125 #ifdef REDEBUG
126 static void at(struct match *, const char *, const char *, const char *,
127     sopno, sopno);
128 #endif
129 #ifdef REDEBUG
130 static const char *pchar(int ch);
131 #endif
132 
133 #ifdef __cplusplus
134 }
135 #endif
136 /* ========= end header generated by ./mkh ========= */
137 
138 #ifdef REDEBUG
139 #define	SP(t, s, c)	print(m, t, s, c, stdout)
140 #define	AT(t, p1, p2, s1, s2)	at(m, t, p1, p2, s1, s2)
141 #define	NOTE(str)	{ if (m->eflags&REG_TRACE) printf("=%s\n", (str)); }
142 #else
143 #define	SP(t, s, c)	/* nothing */
144 #define	AT(t, p1, p2, s1, s2)	/* nothing */
145 #define	NOTE(s)	/* nothing */
146 #endif
147 
148 /*
149  * Given a multibyte string pointed to by start, step back nchar characters
150  * from current position pointed to by cur.
151  */
152 static const char *
stepback(const char * start,const char * cur,int nchar,unsigned int max)153 stepback(const char *start, const char *cur, int nchar, unsigned int max)
154 {
155 	const char *ret;
156 	int wc, mbc;
157 	mbstate_t mbs;
158 	size_t clen;
159 
160 	if (max == 1)
161 		return ((cur - nchar) > start ? cur - nchar : NULL);
162 
163 	ret = cur;
164 	for (wc = nchar; wc > 0; wc--) {
165 		for (mbc = 1; mbc <= max; mbc++) {
166 			if ((ret - mbc) < start)
167 				return (NULL);
168 			memset(&mbs, 0, sizeof (mbs));
169 			clen = mbrtowc(NULL, ret - mbc, mbc, &mbs);
170 			if (clen != (size_t)-1 && clen != (size_t)-2)
171 				break;
172 		}
173 		if (mbc > max)
174 			return (NULL);
175 		ret -= mbc;
176 	}
177 
178 	return (ret);
179 }
180 
181 /*
182  * matcher - the actual matching engine
183  */
184 static int			/* 0 success, REG_NOMATCH failure */
matcher(struct re_guts * g,const char * string,size_t nmatch,regmatch_t pmatch[],int eflags)185 matcher(struct re_guts *g, const char *string, size_t nmatch,
186     regmatch_t pmatch[], int eflags)
187 {
188 	const char *endp;
189 	size_t i;
190 	struct match mv;
191 	struct match *m = &mv;
192 	const char *dp = NULL;
193 	const sopno gf = g->firststate+1;	/* +1 for OEND */
194 	const sopno gl = g->laststate;
195 	const char *start;
196 	const char *stop;
197 	/* Boyer-Moore algorithms variables */
198 	const char *pp;
199 	int cj, mj;
200 	const char *mustfirst;
201 	const char *mustlast;
202 	int *matchjump;
203 	int *charjump;
204 
205 	/* simplify the situation where possible */
206 	if (g->cflags&REG_NOSUB)
207 		nmatch = 0;
208 
209 	if (eflags&REG_STARTEND) {
210 		start = string + pmatch[0].rm_so;
211 		stop = string + pmatch[0].rm_eo;
212 	} else {
213 		start = string;
214 		stop = start + strlen(start);
215 	}
216 
217 	if (stop < start)
218 		return (REG_EFATAL);
219 
220 	/* prescreening; this does wonders for this rather slow code */
221 	if (g->must != NULL) {
222 		if (g->charjump != NULL && g->matchjump != NULL) {
223 			mustfirst = g->must;
224 			mustlast = g->must + g->mlen - 1;
225 			charjump = g->charjump;
226 			matchjump = g->matchjump;
227 			pp = mustlast;
228 			for (dp = start+g->mlen-1; dp < stop; ) {
229 				/* Fast skip non-matches */
230 				while (dp < stop && charjump[(int)*dp])
231 					dp += charjump[(int)*dp];
232 
233 				if (dp >= stop)
234 					break;
235 
236 				/* Greedy matcher */
237 				/*
238 				 * We depend on not being used for
239 				 * for strings of length 1
240 				 */
241 				while (*--dp == *--pp && pp != mustfirst)
242 					;
243 
244 				if (*dp == *pp)
245 					break;
246 
247 				/* Jump to next possible match */
248 				mj = matchjump[pp - mustfirst];
249 				cj = charjump[(int)*dp];
250 				dp += (cj < mj ? mj : cj);
251 				pp = mustlast;
252 			}
253 			if (pp != mustfirst)
254 				return (REG_NOMATCH);
255 		} else {
256 			for (dp = start; dp < stop; dp++)
257 				if (*dp == g->must[0] &&
258 				    stop - dp >= g->mlen &&
259 				    memcmp(dp, g->must, (size_t)g->mlen) == 0)
260 					break;
261 			if (dp == stop)		/* we didn't find g->must */
262 				return (REG_NOMATCH);
263 		}
264 	}
265 
266 	/* match struct setup */
267 	m->g = g;
268 	m->eflags = eflags;
269 	m->pmatch = NULL;
270 	m->lastpos = NULL;
271 	m->offp = string;
272 	m->beginp = start;
273 	m->endp = stop;
274 	STATESETUP(m, 4);
275 	SETUP(m->st);
276 	SETUP(m->fresh);
277 	SETUP(m->tmp);
278 	SETUP(m->empty);
279 	CLEAR(m->empty);
280 	ZAPSTATE(&m->mbs);
281 
282 	/* Adjust start according to moffset, to speed things up */
283 	if (dp != NULL && g->moffset > -1) {
284 		const char *nstart;
285 
286 		nstart = stepback(start, dp, g->moffset, g->mb_cur_max);
287 		if (nstart != NULL)
288 			start = nstart;
289 	}
290 
291 	SP("mloop", m->st, *start);
292 
293 	/* this loop does only one repetition except for backrefs */
294 	for (;;) {
295 		endp = walk(m, start, stop, gf, gl, true);
296 		if (endp == NULL) {		/* a miss */
297 			if (m->pmatch != NULL)
298 				free((char *)m->pmatch);
299 			if (m->lastpos != NULL)
300 				free((char *)m->lastpos);
301 			STATETEARDOWN(m);
302 			return (REG_NOMATCH);
303 		}
304 		if (nmatch == 0 && !g->backrefs)
305 			break;		/* no further info needed */
306 
307 		/* where? */
308 		assert(m->coldp != NULL);
309 		for (;;) {
310 			NOTE("finding start");
311 			endp = walk(m, m->coldp, stop, gf, gl, false);
312 			if (endp != NULL)
313 				break;
314 			assert(m->coldp < m->endp);
315 			m->coldp += XMBRTOWC(NULL, m->coldp,
316 			    m->endp - m->coldp, &m->mbs, 0);
317 		}
318 		if (nmatch == 1 && !g->backrefs)
319 			break;		/* no further info needed */
320 
321 		/* oh my, it wants the subexpressions... */
322 		if (m->pmatch == NULL)
323 			m->pmatch = (regmatch_t *)malloc((m->g->nsub + 1) *
324 			    sizeof (regmatch_t));
325 		if (m->pmatch == NULL) {
326 			STATETEARDOWN(m);
327 			return (REG_ESPACE);
328 		}
329 		for (i = 1; i <= m->g->nsub; i++)
330 			m->pmatch[i].rm_so = m->pmatch[i].rm_eo = -1;
331 		if (!g->backrefs && !(m->eflags&REG_BACKR)) {
332 			NOTE("dissecting");
333 			dp = dissect(m, m->coldp, endp, gf, gl);
334 		} else {
335 			if (g->nplus > 0 && m->lastpos == NULL)
336 				m->lastpos = malloc((g->nplus+1) *
337 				    sizeof (const char *));
338 			if (g->nplus > 0 && m->lastpos == NULL) {
339 				free(m->pmatch);
340 				STATETEARDOWN(m);
341 				return (REG_ESPACE);
342 			}
343 			NOTE("backref dissect");
344 			dp = backref(m, m->coldp, endp, gf, gl, (sopno)0, 0);
345 		}
346 		if (dp != NULL)
347 			break;
348 
349 		/* uh-oh... we couldn't find a subexpression-level match */
350 		assert(g->backrefs);	/* must be back references doing it */
351 		assert(g->nplus == 0 || m->lastpos != NULL);
352 		for (;;) {
353 			if (dp != NULL || endp <= m->coldp)
354 				break;		/* defeat */
355 			NOTE("backoff");
356 			endp = walk(m, m->coldp, endp-1, gf, gl, false);
357 			if (endp == NULL)
358 				break;		/* defeat */
359 			/* try it on a shorter possibility */
360 #ifndef NDEBUG
361 			for (i = 1; i <= m->g->nsub; i++) {
362 				assert(m->pmatch[i].rm_so == -1);
363 				assert(m->pmatch[i].rm_eo == -1);
364 			}
365 #endif
366 			NOTE("backoff dissect");
367 			dp = backref(m, m->coldp, endp, gf, gl, (sopno)0, 0);
368 		}
369 		assert(dp == NULL || dp == endp);
370 		if (dp != NULL)		/* found a shorter one */
371 			break;
372 
373 		/* despite initial appearances, there is no match here */
374 		NOTE("false alarm");
375 		/* recycle starting later */
376 		start = m->coldp + XMBRTOWC(NULL, m->coldp,
377 		    stop - m->coldp, &m->mbs, 0);
378 		assert(start <= stop);
379 	}
380 
381 	/* fill in the details if requested */
382 	if (nmatch > 0) {
383 		pmatch[0].rm_so = m->coldp - m->offp;
384 		pmatch[0].rm_eo = endp - m->offp;
385 	}
386 	if (nmatch > 1) {
387 		assert(m->pmatch != NULL);
388 		for (i = 1; i < nmatch; i++)
389 			if (i <= m->g->nsub)
390 				pmatch[i] = m->pmatch[i];
391 			else {
392 				pmatch[i].rm_so = -1;
393 				pmatch[i].rm_eo = -1;
394 			}
395 	}
396 
397 	if (m->pmatch != NULL)
398 		free((char *)m->pmatch);
399 	if (m->lastpos != NULL)
400 		free((char *)m->lastpos);
401 	STATETEARDOWN(m);
402 	return (0);
403 }
404 
405 /*
406  * dissect - figure out what matched what, no back references
407  */
408 static const char *
dissect(struct match * m,const char * start,const char * stop,sopno startst,sopno stopst)409 dissect(struct match *m, const char *start, const char *stop, sopno startst,
410     sopno stopst)
411 {
412 	int i;
413 	sopno ss;		/* start sop of current subRE */
414 	sopno es;		/* end sop of current subRE */
415 	const char *sp;		/* start of string matched by it */
416 	const char *stp;	/* string matched by it cannot pass here */
417 	const char *rest;	/* start of rest of string */
418 	const char *tail;	/* string unmatched by rest of RE */
419 	sopno ssub;		/* start sop of subsubRE */
420 	sopno esub;		/* end sop of subsubRE */
421 	const char *ssp;	/* start of string matched by subsubRE */
422 	const char *sep;	/* end of string matched by subsubRE */
423 	const char *oldssp;	/* previous ssp */
424 	const char *dp __unused;
425 
426 	AT("diss", start, stop, startst, stopst);
427 	sp = start;
428 	for (ss = startst; ss < stopst; ss = es) {
429 		/* identify end of subRE */
430 		es = ss;
431 		switch (OP(m->g->strip[es])) {
432 		case OPLUS_:
433 		case OQUEST_:
434 			es += OPND(m->g->strip[es]);
435 			break;
436 		case OCH_:
437 			while (OP(m->g->strip[es]) != (sop)O_CH)
438 				es += OPND(m->g->strip[es]);
439 			break;
440 		}
441 		es++;
442 
443 		/* figure out what it matched */
444 		switch (OP(m->g->strip[ss])) {
445 		case OEND:
446 			assert(0);
447 			break;
448 		case OCHAR:
449 			sp += XMBRTOWC(NULL, sp, stop - start, &m->mbs, 0);
450 			break;
451 		case OBOL:
452 		case OEOL:
453 		case OBOW:
454 		case OEOW:
455 			break;
456 		case OANY:
457 		case OANYOF:
458 			sp += XMBRTOWC(NULL, sp, stop - start, &m->mbs, 0);
459 			break;
460 		case OBACK_:
461 		case O_BACK:
462 			assert(0);
463 			break;
464 		/* cases where length of match is hard to find */
465 		case OQUEST_:
466 			stp = stop;
467 			for (;;) {
468 				/* how long could this one be? */
469 				rest = walk(m, sp, stp, ss, es, false);
470 				assert(rest != NULL);	/* it did match */
471 				/* could the rest match the rest? */
472 				tail = walk(m, rest, stop, es, stopst, false);
473 				if (tail == stop)
474 					break;		/* yes! */
475 				/* no -- try a shorter match for this one */
476 				stp = rest - 1;
477 				assert(stp >= sp);	/* it did work */
478 			}
479 			ssub = ss + 1;
480 			esub = es - 1;
481 			/* did innards match? */
482 			if (walk(m, sp, rest, ssub, esub, false) != NULL) {
483 				dp = dissect(m, sp, rest, ssub, esub);
484 				assert(dp == rest);
485 			} else		/* no */
486 				assert(sp == rest);
487 			sp = rest;
488 			break;
489 		case OPLUS_:
490 			stp = stop;
491 			for (;;) {
492 				/* how long could this one be? */
493 				rest = walk(m, sp, stp, ss, es, false);
494 				assert(rest != NULL);	/* it did match */
495 				/* could the rest match the rest? */
496 				tail = walk(m, rest, stop, es, stopst, false);
497 				if (tail == stop)
498 					break;		/* yes! */
499 				/* no -- try a shorter match for this one */
500 				stp = rest - 1;
501 				assert(stp >= sp);	/* it did work */
502 			}
503 			ssub = ss + 1;
504 			esub = es - 1;
505 			ssp = sp;
506 			oldssp = ssp;
507 			for (;;) {	/* find last match of innards */
508 				sep = walk(m, ssp, rest, ssub, esub, false);
509 				if (sep == NULL || sep == ssp)
510 					break;	/* failed or matched null */
511 				oldssp = ssp;	/* on to next try */
512 				ssp = sep;
513 			}
514 			if (sep == NULL) {
515 				/* last successful match */
516 				sep = ssp;
517 				ssp = oldssp;
518 			}
519 			assert(sep == rest);	/* must exhaust substring */
520 			assert(walk(m, ssp, sep, ssub, esub, false) == rest);
521 			dp = dissect(m, ssp, sep, ssub, esub);
522 			assert(dp == sep);
523 			sp = rest;
524 			break;
525 		case OCH_:
526 			stp = stop;
527 			for (;;) {
528 				/* how long could this one be? */
529 				rest = walk(m, sp, stp, ss, es, false);
530 				assert(rest != NULL);	/* it did match */
531 				/* could the rest match the rest? */
532 				tail = walk(m, rest, stop, es, stopst, false);
533 				if (tail == stop)
534 					break;		/* yes! */
535 				/* no -- try a shorter match for this one */
536 				stp = rest - 1;
537 				assert(stp >= sp);	/* it did work */
538 			}
539 			ssub = ss + 1;
540 			esub = ss + OPND(m->g->strip[ss]) - 1;
541 			assert(OP(m->g->strip[esub]) == OOR1);
542 			for (;;) {	/* find first matching branch */
543 				if (walk(m, sp, rest, ssub, esub,
544 				    false) == rest)
545 					break;	/* it matched all of it */
546 				/* that one missed, try next one */
547 				assert(OP(m->g->strip[esub]) == OOR1);
548 				esub++;
549 				assert(OP(m->g->strip[esub]) == OOR2);
550 				ssub = esub + 1;
551 				esub += OPND(m->g->strip[esub]);
552 				if (OP(m->g->strip[esub]) == (sop)OOR2)
553 					esub--;
554 				else
555 					assert(OP(m->g->strip[esub]) == O_CH);
556 			}
557 			dp = dissect(m, sp, rest, ssub, esub);
558 			assert(dp == rest);
559 			sp = rest;
560 			break;
561 		case O_PLUS:
562 		case O_QUEST:
563 		case OOR1:
564 		case OOR2:
565 		case O_CH:
566 			assert(0);
567 			break;
568 		case OLPAREN:
569 			i = OPND(m->g->strip[ss]);
570 			assert(0 < i && i <= m->g->nsub);
571 			m->pmatch[i].rm_so = sp - m->offp;
572 			break;
573 		case ORPAREN:
574 			i = OPND(m->g->strip[ss]);
575 			assert(0 < i && i <= m->g->nsub);
576 			m->pmatch[i].rm_eo = sp - m->offp;
577 			break;
578 		default:		/* uh oh */
579 			assert(0);
580 			break;
581 		}
582 	}
583 
584 	assert(sp == stop);
585 	return (sp);
586 }
587 
588 /*
589  * backref - figure out what matched what, figuring in back references
590  */
591 static const char *
backref(struct match * m,const char * start,const char * stop,sopno startst,sopno stopst,sopno lev,int rec)592 backref(struct match *m, const char *start, const char *stop, sopno startst,
593     sopno stopst, sopno lev,		/* PLUS nesting level */
594     int rec)
595 {
596 	int i;
597 	sopno ss;		/* start sop of current subRE */
598 	const char *sp;		/* start of string matched by it */
599 	sopno ssub;		/* start sop of subsubRE */
600 	sopno esub;		/* end sop of subsubRE */
601 	const char *ssp;	/* start of string matched by subsubRE */
602 	const char *dp;
603 	size_t len;
604 	int hard;
605 	sop s;
606 	regoff_t offsave;
607 	cset *cs;
608 	wint_t wc;
609 
610 	AT("back", start, stop, startst, stopst);
611 	sp = start;
612 
613 	/* get as far as we can with easy stuff */
614 	hard = 0;
615 	for (ss = startst; !hard && ss < stopst; ss++)
616 		switch (OP(s = m->g->strip[ss])) {
617 		case OCHAR:
618 			if (sp == stop)
619 				return (NULL);
620 			sp += XMBRTOWC(&wc, sp, stop - sp, &m->mbs, BADCHAR);
621 			if (wc != OPND(s))
622 				return (NULL);
623 			break;
624 		case OANY:
625 			if (sp == stop)
626 				return (NULL);
627 			sp += XMBRTOWC(&wc, sp, stop - sp, &m->mbs, BADCHAR);
628 			if (wc == BADCHAR)
629 				return (NULL);
630 			break;
631 		case OANYOF:
632 			if (sp == stop)
633 				return (NULL);
634 			cs = &m->g->sets[OPND(s)];
635 			sp += XMBRTOWC(&wc, sp, stop - sp, &m->mbs, BADCHAR);
636 			if (wc == BADCHAR || !CHIN(NC_ENGINE, cs, wc))
637 				return (NULL);
638 			break;
639 		case OBOL:
640 			if ((sp == m->beginp && !(m->eflags&REG_NOTBOL)) ||
641 			    (sp > m->offp && sp < m->endp &&
642 			    *(sp-1) == '\n' && (m->g->cflags&REG_NEWLINE))) {
643 				break;
644 			}
645 			return (NULL);
646 		case OEOL:
647 			if ((sp == m->endp && !(m->eflags&REG_NOTEOL)) ||
648 			    (sp < m->endp && *sp == '\n' &&
649 			    (m->g->cflags&REG_NEWLINE))) {
650 				break;
651 			}
652 			return (NULL);
653 		case OBOW:
654 			if (sp < m->endp && ISWORD(*sp) &&
655 			    ((sp == m->beginp && !(m->eflags&REG_NOTBOL)) ||
656 			    (sp > m->offp && !ISWORD(*(sp-1))))) {
657 				break;
658 			}
659 			return (NULL);
660 		case OEOW:
661 			if (((sp == m->endp && !(m->eflags&REG_NOTEOL)) ||
662 			    (sp < m->endp && *sp == '\n' &&
663 			    (m->g->cflags&REG_NEWLINE)) ||
664 			    (sp < m->endp && !ISWORD(*sp))) &&
665 			    (sp > m->beginp && ISWORD(*(sp-1)))) {
666 				break;
667 			}
668 			return (NULL);
669 		case O_QUEST:
670 			break;
671 		case OOR1:	/* matches null but needs to skip */
672 			ss++;
673 			s = m->g->strip[ss];
674 			do {
675 				assert(OP(s) == OOR2);
676 				ss += OPND(s);
677 			} while (OP(s = m->g->strip[ss]) != (sop)O_CH);
678 			/* note that the ss++ gets us past the O_CH */
679 			break;
680 		default:	/* have to make a choice */
681 			hard = 1;
682 			break;
683 		}
684 	if (!hard) {		/* that was it! */
685 		if (sp != stop)
686 			return (NULL);
687 		return (sp);
688 	}
689 	ss--;			/* adjust for the for's final increment */
690 
691 	/* the hard stuff */
692 	AT("hard", sp, stop, ss, stopst);
693 	s = m->g->strip[ss];
694 	switch (OP(s)) {
695 	case OBACK_:		/* the vilest depths */
696 		i = OPND(s);
697 		assert(0 < i && i <= m->g->nsub);
698 		if (m->pmatch[i].rm_eo == -1)
699 			return (NULL);
700 		assert(m->pmatch[i].rm_so != -1);
701 		len = m->pmatch[i].rm_eo - m->pmatch[i].rm_so;
702 		if (len == 0 && rec++ > MAX_RECURSION)
703 			return (NULL);
704 		assert(stop - m->beginp >= len);
705 		if (sp > stop - len)
706 			return (NULL);	/* not enough left to match */
707 		ssp = m->offp + m->pmatch[i].rm_so;
708 		if (memcmp(sp, ssp, len) != 0)
709 			return (NULL);
710 		while (m->g->strip[ss] != (sop)SOP(O_BACK, i))
711 			ss++;
712 		return (backref(m, sp+len, stop, ss+1, stopst, lev, rec));
713 	case OQUEST_:		/* to null or not */
714 		dp = backref(m, sp, stop, ss+1, stopst, lev, rec);
715 		if (dp != NULL)
716 			return (dp);	/* not */
717 		return (backref(m, sp, stop, ss+OPND(s)+1, stopst, lev, rec));
718 	case OPLUS_:
719 		assert(m->lastpos != NULL);
720 		assert(lev+1 <= m->g->nplus);
721 		m->lastpos[lev+1] = sp;
722 		return (backref(m, sp, stop, ss+1, stopst, lev+1, rec));
723 	case O_PLUS:
724 		if (sp == m->lastpos[lev])	/* last pass matched null */
725 			return (backref(m, sp, stop, ss+1, stopst, lev-1, rec));
726 		/* try another pass */
727 		m->lastpos[lev] = sp;
728 		dp = backref(m, sp, stop, ss-OPND(s)+1, stopst, lev, rec);
729 		if (dp == NULL)
730 			return (backref(m, sp, stop, ss+1, stopst, lev-1, rec));
731 		return (dp);
732 	case OCH_:		/* find the right one, if any */
733 		ssub = ss + 1;
734 		esub = ss + OPND(s) - 1;
735 		assert(OP(m->g->strip[esub]) == OOR1);
736 		for (;;) {	/* find first matching branch */
737 			dp = backref(m, sp, stop, ssub, esub, lev, rec);
738 			if (dp != NULL)
739 				return (dp);
740 			/* that one missed, try next one */
741 			if (OP(m->g->strip[esub]) == (sop)O_CH)
742 				return (NULL);	/* there is none */
743 			esub++;
744 			assert(OP(m->g->strip[esub]) == (sop)OOR2);
745 			ssub = esub + 1;
746 			esub += OPND(m->g->strip[esub]);
747 			if (OP(m->g->strip[esub]) == (sop)OOR2)
748 				esub--;
749 			else
750 				assert(OP(m->g->strip[esub]) == O_CH);
751 		}
752 		/* NOTREACHED */
753 		break;
754 	case OLPAREN:		/* must undo assignment if rest fails */
755 		i = OPND(s);
756 		assert(0 < i && i <= m->g->nsub);
757 		offsave = m->pmatch[i].rm_so;
758 		m->pmatch[i].rm_so = sp - m->offp;
759 		dp = backref(m, sp, stop, ss+1, stopst, lev, rec);
760 		if (dp != NULL)
761 			return (dp);
762 		m->pmatch[i].rm_so = offsave;
763 		return (NULL);
764 	case ORPAREN:		/* must undo assignment if rest fails */
765 		i = OPND(s);
766 		assert(0 < i && i <= m->g->nsub);
767 		offsave = m->pmatch[i].rm_eo;
768 		m->pmatch[i].rm_eo = sp - m->offp;
769 		dp = backref(m, sp, stop, ss+1, stopst, lev, rec);
770 		if (dp != NULL)
771 			return (dp);
772 		m->pmatch[i].rm_eo = offsave;
773 		return (NULL);
774 	default:		/* uh oh */
775 		assert(0);
776 		break;
777 	}
778 
779 	/* "can't happen" */
780 	assert(0);
781 	return (NULL);
782 }
783 
784 /*
785  * Step through the string either quickly or slowly.  Returns where it ended
786  * or NULL.
787  */
788 static const char *
walk(struct match * m,const char * start,const char * stop,sopno startst,sopno stopst,bool fast)789 walk(struct match *m, const char *start, const char *stop, sopno startst,
790     sopno stopst, bool fast)
791 {
792 	states st = m->st;
793 	states fresh = m->fresh;
794 	states empty = m->empty;
795 	states tmp = m->tmp;
796 	const char *p = start;
797 	wint_t c;
798 	wint_t lastc;		/* previous c */
799 	wint_t flagch;
800 	int i;
801 	const char *matchp;	/* last p at which a match ended */
802 	size_t clen;
803 
804 	AT("slow", start, stop, startst, stopst);
805 	CLEAR(st);
806 	SET1(st, startst);
807 	SP("sstart", st, *p);
808 	st = step(m->g, startst, stopst, st, NOTHING, st);
809 	if (fast)
810 		ASSIGN(fresh, st);
811 	matchp = NULL;
812 	if (start == m->offp || (start == m->beginp && !(m->eflags&REG_NOTBOL)))
813 		c = OUT;
814 	else {
815 		/*
816 		 * XXX Wrong if the previous character was multi-byte.
817 		 * Newline never is (in encodings supported by FreeBSD),
818 		 * so this only breaks the ISWORD tests below.
819 		 */
820 		c = (uch)*(start - 1);
821 	}
822 	for (;;) {
823 		/* next character */
824 		lastc = c;
825 		if (p == m->endp) {
826 			c = OUT;
827 			clen = 0;
828 		} else
829 			clen = XMBRTOWC(&c, p, m->endp - p, &m->mbs, BADCHAR);
830 
831 		if (fast && EQ(st, fresh))
832 			matchp = p;
833 
834 		/* is there an EOL and/or BOL between lastc and c? */
835 		flagch = '\0';
836 		i = 0;
837 		if ((lastc == '\n' && m->g->cflags&REG_NEWLINE) ||
838 		    (lastc == OUT && !(m->eflags&REG_NOTBOL))) {
839 			flagch = BOL;
840 			i = m->g->nbol;
841 		}
842 		if ((c == '\n' && m->g->cflags&REG_NEWLINE) ||
843 		    (c == OUT && !(m->eflags&REG_NOTEOL))) {
844 			flagch = (flagch == BOL) ? BOLEOL : EOL;
845 			i += m->g->neol;
846 		}
847 		if (i != 0) {
848 			for (; i > 0; i--)
849 				st = step(m->g, startst, stopst, st,
850 				    flagch, st);
851 			SP("sboleol", st, c);
852 		}
853 
854 		/* how about a word boundary? */
855 		if ((flagch == BOL || (lastc != OUT && !ISWORD(lastc))) &&
856 		    (c != OUT && ISWORD(c))) {
857 			flagch = BOW;
858 		}
859 		if ((lastc != OUT && ISWORD(lastc)) &&
860 		    (flagch == EOL || (c != OUT && !ISWORD(c)))) {
861 			flagch = EOW;
862 		}
863 		if (flagch == BOW || flagch == EOW) {
864 			st = step(m->g, startst, stopst, st, flagch, st);
865 			SP("sboweow", st, c);
866 		}
867 
868 		/* are we done? */
869 		if (ISSET(st, stopst)) {
870 			if (fast)
871 				break;
872 			else
873 				matchp = p;
874 		}
875 		if (EQ(st, empty) || p == stop || clen > (size_t)(stop - p))
876 			break;		/* NOTE BREAK OUT */
877 
878 		/* no, we must deal with this character */
879 		ASSIGN(tmp, st);
880 		if (fast)
881 			ASSIGN(st, fresh);
882 		else
883 			ASSIGN(st, empty);
884 		assert(c != OUT);
885 		st = step(m->g, startst, stopst, tmp, c, st);
886 		SP("saft", st, c);
887 		assert(EQ(step(m->g, startst, stopst, st, NOTHING, st), st));
888 		p += clen;
889 	}
890 
891 	if (fast) {
892 		assert(matchp != NULL);
893 		m->coldp = matchp;
894 		if (ISSET(st, stopst))
895 			return (p + XMBRTOWC(NULL, p, stop - p, &m->mbs, 0));
896 		else
897 			return (NULL);
898 	} else
899 		return (matchp);
900 }
901 
902 /*
903  * step - map set of states reachable before char to set reachable after
904  */
905 static states
step(struct re_guts * g,sopno start,sopno stop,states bef,wint_t ch,states aft)906 step(struct re_guts *g,
907     sopno start,	/* start state within strip */
908     sopno stop,		/* state after stop state within strip */
909     states bef,		/* states reachable before */
910     wint_t ch,		/* character or NONCHAR code */
911     states aft)		/* states already known reachable after */
912 {
913 	cset *cs;
914 	sop s;
915 	sopno pc;
916 	onestate here;		/* note, macros know this name */
917 	sopno look;
918 	int i;
919 
920 	for (pc = start, INIT(here, pc); pc != stop; pc++, INC(here)) {
921 		s = g->strip[pc];
922 		switch (OP(s)) {
923 		case OEND:
924 			assert(pc == stop-1);
925 			break;
926 		case OCHAR:
927 			/* only characters can match */
928 			assert(!NONCHAR(ch) || ch != OPND(s));
929 			if (ch == OPND(s))
930 				FWD(aft, bef, 1);
931 			break;
932 		case OBOL:
933 			if (ch == BOL || ch == BOLEOL)
934 				FWD(aft, bef, 1);
935 			break;
936 		case OEOL:
937 			if (ch == EOL || ch == BOLEOL)
938 				FWD(aft, bef, 1);
939 			break;
940 		case OBOW:
941 			if (ch == BOW)
942 				FWD(aft, bef, 1);
943 			break;
944 		case OEOW:
945 			if (ch == EOW)
946 				FWD(aft, bef, 1);
947 			break;
948 		case OANY:
949 			if (!NONCHAR(ch))
950 				FWD(aft, bef, 1);
951 			break;
952 		case OANYOF:
953 			cs = &g->sets[OPND(s)];
954 			if (!NONCHAR(ch) && CHIN(NC_ENGINE, cs, ch))
955 				FWD(aft, bef, 1);
956 			break;
957 		case OBACK_:		/* ignored here */
958 		case O_BACK:
959 			FWD(aft, aft, 1);
960 			break;
961 		case OPLUS_:		/* forward, this is just an empty */
962 			FWD(aft, aft, 1);
963 			break;
964 		case O_PLUS:		/* both forward and back */
965 			FWD(aft, aft, 1);
966 			i = ISSETBACK(aft, OPND(s));
967 			BACK(aft, aft, OPND(s));
968 			if (!i && ISSETBACK(aft, OPND(s))) {
969 				/* oho, must reconsider loop body */
970 				pc -= OPND(s) + 1;
971 				INIT(here, pc);
972 			}
973 			break;
974 		case OQUEST_:		/* two branches, both forward */
975 			FWD(aft, aft, 1);
976 			FWD(aft, aft, OPND(s));
977 			break;
978 		case O_QUEST:		/* just an empty */
979 			FWD(aft, aft, 1);
980 			break;
981 		case OLPAREN:		/* not significant here */
982 		case ORPAREN:
983 			FWD(aft, aft, 1);
984 			break;
985 		case OCH_:		/* mark the first two branches */
986 			FWD(aft, aft, 1);
987 			assert(OP(g->strip[pc+OPND(s)]) == (sop)OOR2);
988 			FWD(aft, aft, OPND(s));
989 			break;
990 		case OOR1:		/* done a branch, find the O_CH */
991 			if (ISSTATEIN(aft, here)) {
992 				for (look = 1;
993 				    OP(s = g->strip[pc+look]) != (sop)O_CH;
994 				    look += OPND(s))
995 					assert(OP(s) == (sop)OOR2);
996 				FWD(aft, aft, look + 1);
997 			}
998 			break;
999 		case OOR2:		/* propagate OCH_'s marking */
1000 			FWD(aft, aft, 1);
1001 			if (OP(g->strip[pc+OPND(s)]) != (sop)O_CH) {
1002 				assert(OP(g->strip[pc+OPND(s)]) == (sop)OOR2);
1003 				FWD(aft, aft, OPND(s));
1004 			}
1005 			break;
1006 		case O_CH:		/* just empty */
1007 			FWD(aft, aft, 1);
1008 			break;
1009 		default:		/* ooooops... */
1010 			assert(0);
1011 			break;
1012 		}
1013 	}
1014 
1015 	return (aft);
1016 }
1017 
1018 #ifdef REDEBUG
1019 /*
1020  * print - print a set of states
1021  */
1022 static void
print(struct match * m,const char * caption,states st,int ch,FILE * d)1023 print(struct match *m, const char *caption, states st, int ch, FILE *d)
1024 {
1025 	struct re_guts *g = m->g;
1026 	sopno i;
1027 	int first = 1;
1028 
1029 	if (!(m->eflags&REG_TRACE))
1030 		return;
1031 
1032 	(void) fprintf(d, "%s", caption);
1033 	if (ch != '\0')
1034 		(void) fprintf(d, " %s", pchar(ch));
1035 	for (i = 0; i < g->nstates; i++)
1036 		if (ISSET(st, i)) {
1037 			(void) fprintf(d, "%s%d", (first) ? "\t" : ", ", i);
1038 			first = 0;
1039 		}
1040 	(void) fprintf(d, "\n");
1041 }
1042 
1043 /*
1044  * at - print current situation
1045  */
1046 static void
at(struct match * m,const char * title,const char * start,const char * stop,sopno startst,sopno stopst)1047 at(struct match *m, const char *title, const char *start, const char *stop,
1048     sopno startst, sopno stopst)
1049 {
1050 	if (!(m->eflags&REG_TRACE))
1051 		return;
1052 
1053 	(void) printf("%s %s-", title, pchar(*start));
1054 	(void) printf("%s ", pchar(*stop));
1055 	(void) printf("%ld-%ld\n", (long)startst, (long)stopst);
1056 }
1057 
1058 #ifndef PCHARDONE
1059 #define	PCHARDONE	/* never again */
1060 /*
1061  * pchar - make a character printable
1062  *
1063  * Is this identical to regchar() over in debug.c?  Well, yes.  But a
1064  * duplicate here avoids having a debugging-capable regexec.o tied to
1065  * a matching debug.o, and this is convenient.  It all disappears in
1066  * the non-debug compilation anyway, so it doesn't matter much.
1067  */
1068 static const char *
pchar(int ch)1069 pchar(int ch)
1070 {
1071 	static char pbuf[10];
1072 
1073 	if (isprint((uch)ch) || ch == ' ')
1074 		(void) sprintf(pbuf, "%c", ch);
1075 	else
1076 		(void) sprintf(pbuf, "\\%o", ch);
1077 	return (pbuf);
1078 }
1079 #endif
1080 #endif
1081 
1082 #undef	stepback
1083 #undef	matcher
1084 #undef	walk
1085 #undef	dissect
1086 #undef	backref
1087 #undef	step
1088 #undef	print
1089 #undef	at
1090 #undef	match
1091