1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40
41 #include <stdbool.h>
42
43 /*
44 * The matching engine and friends. This file is #included by regexec.c
45 * after suitable #defines of a variety of macros used herein, so that
46 * different state representations can be used without duplicating masses
47 * of code.
48 */
49
50 #ifdef SNAMES
51 #define stepback sstepback
52 #define matcher smatcher
53 #define walk swalk
54 #define dissect sdissect
55 #define backref sbackref
56 #define step sstep
57 #define print sprint
58 #define at sat
59 #define match smat
60 #endif
61 #ifdef LNAMES
62 #define stepback lstepback
63 #define matcher lmatcher
64 #define walk lwalk
65 #define dissect ldissect
66 #define backref lbackref
67 #define step lstep
68 #define print lprint
69 #define at lat
70 #define match lmat
71 #endif
72 #ifdef MNAMES
73 #define stepback mstepback
74 #define matcher mmatcher
75 #define walk mwalk
76 #define dissect mdissect
77 #define backref mbackref
78 #define step mstep
79 #define print mprint
80 #define at mat
81 #define match mmat
82 #endif
83
84 /* another structure passed up and down to avoid zillions of parameters */
85 struct match {
86 struct re_guts *g;
87 int eflags;
88 regmatch_t *pmatch; /* [nsub+1] (0 element unused) */
89 const char *offp; /* offsets work from here */
90 const char *beginp; /* start of string -- virtual NUL precedes */
91 const char *endp; /* end of string -- virtual NUL here */
92 const char *coldp; /* can be no match starting before here */
93 const char **lastpos; /* [nplus+1] */
94 STATEVARS;
95 states st; /* current states */
96 states fresh; /* states for a fresh start */
97 states tmp; /* temporary */
98 states empty; /* empty set of states */
99 mbstate_t mbs; /* multibyte conversion state */
100 };
101
102 /* ========= begin header generated by ./mkh ========= */
103 #ifdef __cplusplus
104 extern "C" {
105 #endif
106
107 /* === engine.c === */
108 static int matcher(struct re_guts *g, const char *string, size_t nmatch, regmatch_t pmatch[], int eflags);
109 static const char *dissect(struct match *m, const char *start, const char *stop, sopno startst, sopno stopst);
110 static const char *backref(struct match *m, const char *start, const char *stop, sopno startst, sopno stopst, sopno lev, int);
111 static const char *walk(struct match *m, const char *start, const char *stop, sopno startst, sopno stopst, bool fast);
112 static states step(struct re_guts *g, sopno start, sopno stop, states bef, wint_t ch, states aft);
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 *m, const char *caption, states st, int ch, FILE *d);
124 #endif
125 #ifdef REDEBUG
126 static void at(struct match *m, const char *title, const char *start, const char *stop, sopno startst, sopno stopst);
127 #endif
128 #ifdef REDEBUG
129 static const char *pchar(int ch);
130 #endif
131
132 #ifdef __cplusplus
133 }
134 #endif
135 /* ========= end header generated by ./mkh ========= */
136
137 #ifdef REDEBUG
138 #define SP(t, s, c) print(m, t, s, c, stdout)
139 #define AT(t, p1, p2, s1, s2) at(m, t, p1, p2, s1, s2)
140 #define NOTE(str) { if (m->eflags®_TRACE) printf("=%s\n", (str)); }
141 #else
142 #define SP(t, s, c) /* nothing */
143 #define AT(t, p1, p2, s1, s2) /* nothing */
144 #define NOTE(s) /* nothing */
145 #endif
146
147 /*
148 * Given a multibyte string pointed to by start, step back nchar characters
149 * from current position pointed to by cur.
150 */
151 static const char *
stepback(const char * start,const char * cur,int nchar)152 stepback(const char *start, const char *cur, int nchar)
153 {
154 const char *ret;
155 int wc, mbc;
156 mbstate_t mbs;
157 size_t clen;
158
159 if (MB_CUR_MAX == 1)
160 return ((cur - nchar) > start ? cur - nchar : NULL);
161
162 ret = cur;
163 for (wc = nchar; wc > 0; wc--) {
164 for (mbc = 1; mbc <= MB_CUR_MAX; mbc++) {
165 if ((ret - mbc) < start)
166 return (NULL);
167 memset(&mbs, 0, sizeof(mbs));
168 clen = mbrtowc(NULL, ret - mbc, mbc, &mbs);
169 if (clen != (size_t)-1 && clen != (size_t)-2)
170 break;
171 }
172 if (mbc > MB_CUR_MAX)
173 return (NULL);
174 ret -= mbc;
175 }
176
177 return (ret);
178 }
179
180 /*
181 - matcher - the actual matching engine
182 == static int matcher(struct re_guts *g, const char *string, \
183 == size_t nmatch, regmatch_t pmatch[], int eflags);
184 */
185 static int /* 0 success, REG_NOMATCH failure */
matcher(struct re_guts * g,const char * string,size_t nmatch,regmatch_t pmatch[],int eflags)186 matcher(struct re_guts *g,
187 const char *string,
188 size_t nmatch,
189 regmatch_t pmatch[],
190 int eflags)
191 {
192 const char *endp;
193 size_t i;
194 struct match mv;
195 struct match *m = &mv;
196 const char *dp = NULL;
197 const sopno gf = g->firststate+1; /* +1 for OEND */
198 const sopno gl = g->laststate;
199 const char *start;
200 const char *stop;
201 /* Boyer-Moore algorithms variables */
202 const char *pp;
203 int cj, mj;
204 const char *mustfirst;
205 const char *mustlast;
206 int *matchjump;
207 int *charjump;
208
209 /* simplify the situation where possible */
210 if (g->cflags®_NOSUB)
211 nmatch = 0;
212 if (eflags®_STARTEND) {
213 start = string + pmatch[0].rm_so;
214 stop = string + pmatch[0].rm_eo;
215 } else {
216 start = string;
217 stop = start + strlen(start);
218 }
219 if (stop < start)
220 return(REG_INVARG);
221
222 /* prescreening; this does wonders for this rather slow code */
223 if (g->must != NULL) {
224 if (g->charjump != NULL && g->matchjump != NULL) {
225 mustfirst = g->must;
226 mustlast = g->must + g->mlen - 1;
227 charjump = g->charjump;
228 matchjump = g->matchjump;
229 pp = mustlast;
230 for (dp = start+g->mlen-1; dp < stop;) {
231 /* Fast skip non-matches */
232 while (dp < stop && charjump[(int)*dp])
233 dp += charjump[(int)*dp];
234
235 if (dp >= stop)
236 break;
237
238 /* Greedy matcher */
239 /* We depend on not being used for
240 * for strings of length 1
241 */
242 while (*--dp == *--pp && pp != mustfirst);
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);
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, he 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 == static const char *dissect(struct match *m, const char *start, \
408 == const char *stop, sopno startst, sopno stopst);
409 */
410 static const char * /* == stop (success) always */
dissect(struct match * m,const char * start,const char * stop,sopno startst,sopno stopst)411 dissect(struct match *m,
412 const char *start,
413 const char *stop,
414 sopno startst,
415 sopno stopst)
416 {
417 int i;
418 sopno ss; /* start sop of current subRE */
419 sopno es; /* end sop of current subRE */
420 const char *sp; /* start of string matched by it */
421 const char *stp; /* string matched by it cannot pass here */
422 const char *rest; /* start of rest of string */
423 const char *tail; /* string unmatched by rest of RE */
424 sopno ssub; /* start sop of subsubRE */
425 sopno esub; /* end sop of subsubRE */
426 const char *ssp; /* start of string matched by subsubRE */
427 const char *sep; /* end of string matched by subsubRE */
428 const char *oldssp; /* previous ssp */
429 const char *dp __unused;
430
431 AT("diss", start, stop, startst, stopst);
432 sp = start;
433 for (ss = startst; ss < stopst; ss = es) {
434 /* identify end of subRE */
435 es = ss;
436 switch (OP(m->g->strip[es])) {
437 case OPLUS_:
438 case OQUEST_:
439 es += OPND(m->g->strip[es]);
440 break;
441 case OCH_:
442 while (OP(m->g->strip[es]) != (sop)O_CH)
443 es += OPND(m->g->strip[es]);
444 break;
445 }
446 es++;
447
448 /* figure out what it matched */
449 switch (OP(m->g->strip[ss])) {
450 case OEND:
451 assert(nope);
452 break;
453 case OCHAR:
454 sp += XMBRTOWC(NULL, sp, stop - start, &m->mbs, 0);
455 break;
456 case OBOL:
457 case OEOL:
458 case OBOW:
459 case OEOW:
460 break;
461 case OANY:
462 case OANYOF:
463 sp += XMBRTOWC(NULL, sp, stop - start, &m->mbs, 0);
464 break;
465 case OBACK_:
466 case O_BACK:
467 assert(nope);
468 break;
469 /* cases where length of match is hard to find */
470 case OQUEST_:
471 stp = stop;
472 for (;;) {
473 /* how long could this one be? */
474 rest = walk(m, sp, stp, ss, es, false);
475 assert(rest != NULL); /* it did match */
476 /* could the rest match the rest? */
477 tail = walk(m, rest, stop, es, stopst, false);
478 if (tail == stop)
479 break; /* yes! */
480 /* no -- try a shorter match for this one */
481 stp = rest - 1;
482 assert(stp >= sp); /* it did work */
483 }
484 ssub = ss + 1;
485 esub = es - 1;
486 /* did innards match? */
487 if (walk(m, sp, rest, ssub, esub, false) != NULL) {
488 dp = dissect(m, sp, rest, ssub, esub);
489 assert(dp == rest);
490 } else /* no */
491 assert(sp == rest);
492 sp = rest;
493 break;
494 case OPLUS_:
495 stp = stop;
496 for (;;) {
497 /* how long could this one be? */
498 rest = walk(m, sp, stp, ss, es, false);
499 assert(rest != NULL); /* it did match */
500 /* could the rest match the rest? */
501 tail = walk(m, rest, stop, es, stopst, false);
502 if (tail == stop)
503 break; /* yes! */
504 /* no -- try a shorter match for this one */
505 stp = rest - 1;
506 assert(stp >= sp); /* it did work */
507 }
508 ssub = ss + 1;
509 esub = es - 1;
510 ssp = sp;
511 oldssp = ssp;
512 for (;;) { /* find last match of innards */
513 sep = walk(m, ssp, rest, ssub, esub, false);
514 if (sep == NULL || sep == ssp)
515 break; /* failed or matched null */
516 oldssp = ssp; /* on to next try */
517 ssp = sep;
518 }
519 if (sep == NULL) {
520 /* last successful match */
521 sep = ssp;
522 ssp = oldssp;
523 }
524 assert(sep == rest); /* must exhaust substring */
525 assert(walk(m, ssp, sep, ssub, esub, false) == rest);
526 dp = dissect(m, ssp, sep, ssub, esub);
527 assert(dp == sep);
528 sp = rest;
529 break;
530 case OCH_:
531 stp = stop;
532 for (;;) {
533 /* how long could this one be? */
534 rest = walk(m, sp, stp, ss, es, false);
535 assert(rest != NULL); /* it did match */
536 /* could the rest match the rest? */
537 tail = walk(m, rest, stop, es, stopst, false);
538 if (tail == stop)
539 break; /* yes! */
540 /* no -- try a shorter match for this one */
541 stp = rest - 1;
542 assert(stp >= sp); /* it did work */
543 }
544 ssub = ss + 1;
545 esub = ss + OPND(m->g->strip[ss]) - 1;
546 assert(OP(m->g->strip[esub]) == OOR1);
547 for (;;) { /* find first matching branch */
548 if (walk(m, sp, rest, ssub, esub, false) == rest)
549 break; /* it matched all of it */
550 /* that one missed, try next one */
551 assert(OP(m->g->strip[esub]) == OOR1);
552 esub++;
553 assert(OP(m->g->strip[esub]) == OOR2);
554 ssub = esub + 1;
555 esub += OPND(m->g->strip[esub]);
556 if (OP(m->g->strip[esub]) == (sop)OOR2)
557 esub--;
558 else
559 assert(OP(m->g->strip[esub]) == O_CH);
560 }
561 dp = dissect(m, sp, rest, ssub, esub);
562 assert(dp == rest);
563 sp = rest;
564 break;
565 case O_PLUS:
566 case O_QUEST:
567 case OOR1:
568 case OOR2:
569 case O_CH:
570 assert(nope);
571 break;
572 case OLPAREN:
573 i = OPND(m->g->strip[ss]);
574 assert(0 < i && i <= m->g->nsub);
575 m->pmatch[i].rm_so = sp - m->offp;
576 break;
577 case ORPAREN:
578 i = OPND(m->g->strip[ss]);
579 assert(0 < i && i <= m->g->nsub);
580 m->pmatch[i].rm_eo = sp - m->offp;
581 break;
582 default: /* uh oh */
583 assert(nope);
584 break;
585 }
586 }
587
588 assert(sp == stop);
589 return(sp);
590 }
591
592 /*
593 - backref - figure out what matched what, figuring in back references
594 == static const char *backref(struct match *m, const char *start, \
595 == const char *stop, sopno startst, sopno stopst, sopno lev);
596 */
597 static const char * /* == stop (success) or NULL (failure) */
backref(struct match * m,const char * start,const char * stop,sopno startst,sopno stopst,sopno lev,int rec)598 backref(struct match *m,
599 const char *start,
600 const char *stop,
601 sopno startst,
602 sopno stopst,
603 sopno lev, /* PLUS nesting level */
604 int rec)
605 {
606 int i;
607 sopno ss; /* start sop of current subRE */
608 const char *sp; /* start of string matched by it */
609 sopno ssub; /* start sop of subsubRE */
610 sopno esub; /* end sop of subsubRE */
611 const char *ssp; /* start of string matched by subsubRE */
612 const char *dp;
613 size_t len;
614 int hard;
615 sop s;
616 regoff_t offsave;
617 cset *cs;
618 wint_t wc;
619
620 AT("back", start, stop, startst, stopst);
621 sp = start;
622
623 /* get as far as we can with easy stuff */
624 hard = 0;
625 for (ss = startst; !hard && ss < stopst; ss++)
626 switch (OP(s = m->g->strip[ss])) {
627 case OCHAR:
628 if (sp == stop)
629 return(NULL);
630 sp += XMBRTOWC(&wc, sp, stop - sp, &m->mbs, BADCHAR);
631 if (wc != OPND(s))
632 return(NULL);
633 break;
634 case OANY:
635 if (sp == stop)
636 return(NULL);
637 sp += XMBRTOWC(&wc, sp, stop - sp, &m->mbs, BADCHAR);
638 if (wc == BADCHAR)
639 return (NULL);
640 break;
641 case OANYOF:
642 if (sp == stop)
643 return (NULL);
644 cs = &m->g->sets[OPND(s)];
645 sp += XMBRTOWC(&wc, sp, stop - sp, &m->mbs, BADCHAR);
646 if (wc == BADCHAR || !CHIN(cs, wc))
647 return(NULL);
648 break;
649 case OBOL:
650 if ((sp == m->beginp && !(m->eflags®_NOTBOL)) ||
651 (sp > m->offp && sp < m->endp &&
652 *(sp-1) == '\n' && (m->g->cflags®_NEWLINE)))
653 { /* yes */ }
654 else
655 return(NULL);
656 break;
657 case OEOL:
658 if ( (sp == m->endp && !(m->eflags®_NOTEOL)) ||
659 (sp < m->endp && *sp == '\n' &&
660 (m->g->cflags®_NEWLINE)) )
661 { /* yes */ }
662 else
663 return(NULL);
664 break;
665 case OBOW:
666 if (sp < m->endp && ISWORD(*sp) &&
667 ((sp == m->beginp && !(m->eflags®_NOTBOL)) ||
668 (sp > m->offp && !ISWORD(*(sp-1)))))
669 { /* yes */ }
670 else
671 return(NULL);
672 break;
673 case OEOW:
674 if (( (sp == m->endp && !(m->eflags®_NOTEOL)) ||
675 (sp < m->endp && *sp == '\n' &&
676 (m->g->cflags®_NEWLINE)) ||
677 (sp < m->endp && !ISWORD(*sp)) ) &&
678 (sp > m->beginp && ISWORD(*(sp-1))) )
679 { /* yes */ }
680 else
681 return(NULL);
682 break;
683 case O_QUEST:
684 break;
685 case OOR1: /* matches null but needs to skip */
686 ss++;
687 s = m->g->strip[ss];
688 do {
689 assert(OP(s) == OOR2);
690 ss += OPND(s);
691 } while (OP(s = m->g->strip[ss]) != (sop)O_CH);
692 /* note that the ss++ gets us past the O_CH */
693 break;
694 default: /* have to make a choice */
695 hard = 1;
696 break;
697 }
698 if (!hard) { /* that was it! */
699 if (sp != stop)
700 return(NULL);
701 return(sp);
702 }
703 ss--; /* adjust for the for's final increment */
704
705 /* the hard stuff */
706 AT("hard", sp, stop, ss, stopst);
707 s = m->g->strip[ss];
708 switch (OP(s)) {
709 case OBACK_: /* the vilest depths */
710 i = OPND(s);
711 assert(0 < i && i <= m->g->nsub);
712 if (m->pmatch[i].rm_eo == -1)
713 return(NULL);
714 assert(m->pmatch[i].rm_so != -1);
715 len = m->pmatch[i].rm_eo - m->pmatch[i].rm_so;
716 if (len == 0 && rec++ > MAX_RECURSION)
717 return(NULL);
718 assert(stop - m->beginp >= len);
719 if (sp > stop - len)
720 return(NULL); /* not enough left to match */
721 ssp = m->offp + m->pmatch[i].rm_so;
722 if (memcmp(sp, ssp, len) != 0)
723 return(NULL);
724 while (m->g->strip[ss] != (sop)SOP(O_BACK, i))
725 ss++;
726 return(backref(m, sp+len, stop, ss+1, stopst, lev, rec));
727 case OQUEST_: /* to null or not */
728 dp = backref(m, sp, stop, ss+1, stopst, lev, rec);
729 if (dp != NULL)
730 return(dp); /* not */
731 return(backref(m, sp, stop, ss+OPND(s)+1, stopst, lev, rec));
732 case OPLUS_:
733 assert(m->lastpos != NULL);
734 assert(lev+1 <= m->g->nplus);
735 m->lastpos[lev+1] = sp;
736 return(backref(m, sp, stop, ss+1, stopst, lev+1, rec));
737 case O_PLUS:
738 if (sp == m->lastpos[lev]) /* last pass matched null */
739 return(backref(m, sp, stop, ss+1, stopst, lev-1, rec));
740 /* try another pass */
741 m->lastpos[lev] = sp;
742 dp = backref(m, sp, stop, ss-OPND(s)+1, stopst, lev, rec);
743 if (dp == NULL)
744 return(backref(m, sp, stop, ss+1, stopst, lev-1, rec));
745 else
746 return(dp);
747 case OCH_: /* find the right one, if any */
748 ssub = ss + 1;
749 esub = ss + OPND(s) - 1;
750 assert(OP(m->g->strip[esub]) == OOR1);
751 for (;;) { /* find first matching branch */
752 dp = backref(m, sp, stop, ssub, esub, lev, rec);
753 if (dp != NULL)
754 return(dp);
755 /* that one missed, try next one */
756 if (OP(m->g->strip[esub]) == (sop)O_CH)
757 return(NULL); /* there is none */
758 esub++;
759 assert(OP(m->g->strip[esub]) == (sop)OOR2);
760 ssub = esub + 1;
761 esub += OPND(m->g->strip[esub]);
762 if (OP(m->g->strip[esub]) == (sop)OOR2)
763 esub--;
764 else
765 assert(OP(m->g->strip[esub]) == O_CH);
766 }
767 /* NOTREACHED */
768 break;
769 case OLPAREN: /* must undo assignment if rest fails */
770 i = OPND(s);
771 assert(0 < i && i <= m->g->nsub);
772 offsave = m->pmatch[i].rm_so;
773 m->pmatch[i].rm_so = sp - m->offp;
774 dp = backref(m, sp, stop, ss+1, stopst, lev, rec);
775 if (dp != NULL)
776 return(dp);
777 m->pmatch[i].rm_so = offsave;
778 return(NULL);
779 case ORPAREN: /* must undo assignment if rest fails */
780 i = OPND(s);
781 assert(0 < i && i <= m->g->nsub);
782 offsave = m->pmatch[i].rm_eo;
783 m->pmatch[i].rm_eo = sp - m->offp;
784 dp = backref(m, sp, stop, ss+1, stopst, lev, rec);
785 if (dp != NULL)
786 return(dp);
787 m->pmatch[i].rm_eo = offsave;
788 return(NULL);
789 default: /* uh oh */
790 assert(nope);
791 break;
792 }
793
794 /* "can't happen" */
795 assert(nope);
796 /* NOTREACHED */
797 return "shut up gcc";
798 }
799
800 /*
801 - walk - step through the string either quickly or slowly
802 == static const char *walk(struct match *m, const char *start, \
803 == const char *stop, sopno startst, sopno stopst, bool fast);
804 */
805 static const char * /* where it ended, or NULL */
walk(struct match * m,const char * start,const char * stop,sopno startst,sopno stopst,bool fast)806 walk(struct match *m, const char *start, const char *stop, sopno startst,
807 sopno stopst, bool fast)
808 {
809 states st = m->st;
810 states fresh = m->fresh;
811 states empty = m->empty;
812 states tmp = m->tmp;
813 const char *p = start;
814 wint_t c;
815 wint_t lastc; /* previous c */
816 wint_t flagch;
817 int i;
818 const char *matchp; /* last p at which a match ended */
819 size_t clen;
820
821 AT("slow", start, stop, startst, stopst);
822 CLEAR(st);
823 SET1(st, startst);
824 SP("sstart", st, *p);
825 st = step(m->g, startst, stopst, st, NOTHING, st);
826 if (fast)
827 ASSIGN(fresh, st);
828 matchp = NULL;
829 if (start == m->offp || (start == m->beginp && !(m->eflags®_NOTBOL)))
830 c = OUT;
831 else {
832 /*
833 * XXX Wrong if the previous character was multi-byte.
834 * Newline never is (in encodings supported by FreeBSD),
835 * so this only breaks the ISWORD tests below.
836 */
837 c = (uch)*(start - 1);
838 }
839 for (;;) {
840 /* next character */
841 lastc = c;
842 if (p == m->endp) {
843 c = OUT;
844 clen = 0;
845 } else
846 clen = XMBRTOWC(&c, p, m->endp - p, &m->mbs, BADCHAR);
847
848 if (fast && EQ(st, fresh))
849 matchp = p;
850
851 /* is there an EOL and/or BOL between lastc and c? */
852 flagch = '\0';
853 i = 0;
854 if ( (lastc == '\n' && m->g->cflags®_NEWLINE) ||
855 (lastc == OUT && !(m->eflags®_NOTBOL)) ) {
856 flagch = BOL;
857 i = m->g->nbol;
858 }
859 if ( (c == '\n' && m->g->cflags®_NEWLINE) ||
860 (c == OUT && !(m->eflags®_NOTEOL)) ) {
861 flagch = (flagch == BOL) ? BOLEOL : EOL;
862 i += m->g->neol;
863 }
864 if (i != 0) {
865 for (; i > 0; i--)
866 st = step(m->g, startst, stopst, st, flagch, st);
867 SP("sboleol", st, c);
868 }
869
870 /* how about a word boundary? */
871 if ( (flagch == BOL || (lastc != OUT && !ISWORD(lastc))) &&
872 (c != OUT && ISWORD(c)) ) {
873 flagch = BOW;
874 }
875 if ( (lastc != OUT && ISWORD(lastc)) &&
876 (flagch == EOL || (c != OUT && !ISWORD(c))) ) {
877 flagch = EOW;
878 }
879 if (flagch == BOW || flagch == EOW) {
880 st = step(m->g, startst, stopst, st, flagch, st);
881 SP("sboweow", st, c);
882 }
883
884 /* are we done? */
885 if (ISSET(st, stopst)) {
886 if (fast)
887 break;
888 else
889 matchp = p;
890 }
891 if (EQ(st, empty) || p == stop || clen > (size_t)(stop - p))
892 break; /* NOTE BREAK OUT */
893
894 /* no, we must deal with this character */
895 ASSIGN(tmp, st);
896 if (fast)
897 ASSIGN(st, fresh);
898 else
899 ASSIGN(st, empty);
900 assert(c != OUT);
901 st = step(m->g, startst, stopst, tmp, c, st);
902 SP("saft", st, c);
903 assert(EQ(step(m->g, startst, stopst, st, NOTHING, st), st));
904 p += clen;
905 }
906
907 if (fast) {
908 assert(matchp != NULL);
909 m->coldp = matchp;
910 if (ISSET(st, stopst))
911 return (p + XMBRTOWC(NULL, p, stop - p, &m->mbs, 0));
912 else
913 return (NULL);
914 } else
915 return (matchp);
916 }
917
918 /*
919 - step - map set of states reachable before char to set reachable after
920 == static states step(struct re_guts *g, sopno start, sopno stop, \
921 == states bef, int ch, states aft);
922 == #define BOL (OUT-1)
923 == #define EOL (BOL-1)
924 == #define BOLEOL (BOL-2)
925 == #define NOTHING (BOL-3)
926 == #define BOW (BOL-4)
927 == #define EOW (BOL-5)
928 == #define BADCHAR (BOL-6)
929 == #define NONCHAR(c) ((c) <= OUT)
930 */
931 static states
step(struct re_guts * g,sopno start,sopno stop,states bef,wint_t ch,states aft)932 step(struct re_guts *g,
933 sopno start, /* start state within strip */
934 sopno stop, /* state after stop state within strip */
935 states bef, /* states reachable before */
936 wint_t ch, /* character or NONCHAR code */
937 states aft) /* states already known reachable after */
938 {
939 cset *cs;
940 sop s;
941 sopno pc;
942 onestate here; /* note, macros know this name */
943 sopno look;
944 int i;
945
946 for (pc = start, INIT(here, pc); pc != stop; pc++, INC(here)) {
947 s = g->strip[pc];
948 switch (OP(s)) {
949 case OEND:
950 assert(pc == stop-1);
951 break;
952 case OCHAR:
953 /* only characters can match */
954 assert(!NONCHAR(ch) || ch != OPND(s));
955 if (ch == OPND(s))
956 FWD(aft, bef, 1);
957 break;
958 case OBOL:
959 if (ch == BOL || ch == BOLEOL)
960 FWD(aft, bef, 1);
961 break;
962 case OEOL:
963 if (ch == EOL || ch == BOLEOL)
964 FWD(aft, bef, 1);
965 break;
966 case OBOW:
967 if (ch == BOW)
968 FWD(aft, bef, 1);
969 break;
970 case OEOW:
971 if (ch == EOW)
972 FWD(aft, bef, 1);
973 break;
974 case OANY:
975 if (!NONCHAR(ch))
976 FWD(aft, bef, 1);
977 break;
978 case OANYOF:
979 cs = &g->sets[OPND(s)];
980 if (!NONCHAR(ch) && CHIN(cs, ch))
981 FWD(aft, bef, 1);
982 break;
983 case OBACK_: /* ignored here */
984 case O_BACK:
985 FWD(aft, aft, 1);
986 break;
987 case OPLUS_: /* forward, this is just an empty */
988 FWD(aft, aft, 1);
989 break;
990 case O_PLUS: /* both forward and back */
991 FWD(aft, aft, 1);
992 i = ISSETBACK(aft, OPND(s));
993 BACK(aft, aft, OPND(s));
994 if (!i && ISSETBACK(aft, OPND(s))) {
995 /* oho, must reconsider loop body */
996 pc -= OPND(s) + 1;
997 INIT(here, pc);
998 }
999 break;
1000 case OQUEST_: /* two branches, both forward */
1001 FWD(aft, aft, 1);
1002 FWD(aft, aft, OPND(s));
1003 break;
1004 case O_QUEST: /* just an empty */
1005 FWD(aft, aft, 1);
1006 break;
1007 case OLPAREN: /* not significant here */
1008 case ORPAREN:
1009 FWD(aft, aft, 1);
1010 break;
1011 case OCH_: /* mark the first two branches */
1012 FWD(aft, aft, 1);
1013 assert(OP(g->strip[pc+OPND(s)]) == (sop)OOR2);
1014 FWD(aft, aft, OPND(s));
1015 break;
1016 case OOR1: /* done a branch, find the O_CH */
1017 if (ISSTATEIN(aft, here)) {
1018 for (look = 1;
1019 OP(s = g->strip[pc+look]) != (sop)O_CH;
1020 look += OPND(s))
1021 assert(OP(s) == (sop)OOR2);
1022 FWD(aft, aft, look + 1);
1023 }
1024 break;
1025 case OOR2: /* propagate OCH_'s marking */
1026 FWD(aft, aft, 1);
1027 if (OP(g->strip[pc+OPND(s)]) != (sop)O_CH) {
1028 assert(OP(g->strip[pc+OPND(s)]) == (sop)OOR2);
1029 FWD(aft, aft, OPND(s));
1030 }
1031 break;
1032 case O_CH: /* just empty */
1033 FWD(aft, aft, 1);
1034 break;
1035 default: /* ooooops... */
1036 assert(nope);
1037 break;
1038 }
1039 }
1040
1041 return(aft);
1042 }
1043
1044 #ifdef REDEBUG
1045 /*
1046 - print - print a set of states
1047 == #ifdef REDEBUG
1048 == static void print(struct match *m, const char *caption, states st, \
1049 == int ch, FILE *d);
1050 == #endif
1051 */
1052 static void
print(struct match * m,const char * caption,states st,int ch,FILE * d)1053 print(struct match *m,
1054 const char *caption,
1055 states st,
1056 int ch,
1057 FILE *d)
1058 {
1059 struct re_guts *g = m->g;
1060 sopno i;
1061 int first = 1;
1062
1063 if (!(m->eflags®_TRACE))
1064 return;
1065
1066 fprintf(d, "%s", caption);
1067 if (ch != '\0')
1068 fprintf(d, " %s", pchar(ch));
1069 for (i = 0; i < g->nstates; i++)
1070 if (ISSET(st, i)) {
1071 fprintf(d, "%s%d", (first) ? "\t" : ", ", i);
1072 first = 0;
1073 }
1074 fprintf(d, "\n");
1075 }
1076
1077 /*
1078 - at - print current situation
1079 == #ifdef REDEBUG
1080 == static void at(struct match *m, const char *title, const char *start, \
1081 == const char *stop, sopno startst, sopno stopst);
1082 == #endif
1083 */
1084 static void
at(struct match * m,const char * title,const char * start,const char * stop,sopno startst,sopno stopst)1085 at( struct match *m,
1086 const char *title,
1087 const char *start,
1088 const char *stop,
1089 sopno startst,
1090 sopno stopst)
1091 {
1092 if (!(m->eflags®_TRACE))
1093 return;
1094
1095 printf("%s %s-", title, pchar(*start));
1096 printf("%s ", pchar(*stop));
1097 printf("%ld-%ld\n", (long)startst, (long)stopst);
1098 }
1099
1100 #ifndef PCHARDONE
1101 #define PCHARDONE /* never again */
1102 /*
1103 - pchar - make a character printable
1104 == #ifdef REDEBUG
1105 == static const char *pchar(int ch);
1106 == #endif
1107 *
1108 * Is this identical to regchar() over in debug.c? Well, yes. But a
1109 * duplicate here avoids having a debugging-capable regexec.o tied to
1110 * a matching debug.o, and this is convenient. It all disappears in
1111 * the non-debug compilation anyway, so it doesn't matter much.
1112 */
1113 static const char * /* -> representation */
pchar(int ch)1114 pchar(int ch)
1115 {
1116 static char pbuf[10];
1117
1118 if (isprint((uch)ch) || ch == ' ')
1119 sprintf(pbuf, "%c", ch);
1120 else
1121 sprintf(pbuf, "\\%o", ch);
1122 return(pbuf);
1123 }
1124 #endif
1125 #endif
1126
1127 #undef stepback
1128 #undef matcher
1129 #undef walk
1130 #undef dissect
1131 #undef backref
1132 #undef step
1133 #undef print
1134 #undef at
1135 #undef match
1136