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®_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®_NOSUB)
207 nmatch = 0;
208
209 if (eflags®_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®_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®_NOTBOL)) ||
641 (sp > m->offp && sp < m->endp &&
642 *(sp-1) == '\n' && (m->g->cflags®_NEWLINE))) {
643 break;
644 }
645 return (NULL);
646 case OEOL:
647 if ((sp == m->endp && !(m->eflags®_NOTEOL)) ||
648 (sp < m->endp && *sp == '\n' &&
649 (m->g->cflags®_NEWLINE))) {
650 break;
651 }
652 return (NULL);
653 case OBOW:
654 if (sp < m->endp && ISWORD(*sp) &&
655 ((sp == m->beginp && !(m->eflags®_NOTBOL)) ||
656 (sp > m->offp && !ISWORD(*(sp-1))))) {
657 break;
658 }
659 return (NULL);
660 case OEOW:
661 if (((sp == m->endp && !(m->eflags®_NOTEOL)) ||
662 (sp < m->endp && *sp == '\n' &&
663 (m->g->cflags®_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®_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®_NEWLINE) ||
838 (lastc == OUT && !(m->eflags®_NOTBOL))) {
839 flagch = BOL;
840 i = m->g->nbol;
841 }
842 if ((c == '\n' && m->g->cflags®_NEWLINE) ||
843 (c == OUT && !(m->eflags®_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®_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®_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