/[pcre]/code/trunk/pcre_study.c
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Revision 604 - (show annotations) (download)
Thu Jun 2 19:04:54 2011 UTC (3 years, 1 month ago) by ph10
File MIME type: text/plain
File size: 34716 byte(s)
Refactoring to reduce stack usage for possessively quantified subpatterns. Also 
fixed a number of bugs related to repeated subpatterns. Some further tidies 
consequent on the removal of OP_OPT are also in this patch.

1 /*************************************************
2 * Perl-Compatible Regular Expressions *
3 *************************************************/
4
5 /* PCRE is a library of functions to support regular expressions whose syntax
6 and semantics are as close as possible to those of the Perl 5 language.
7
8 Written by Philip Hazel
9 Copyright (c) 1997-2010 University of Cambridge
10
11 -----------------------------------------------------------------------------
12 Redistribution and use in source and binary forms, with or without
13 modification, are permitted provided that the following conditions are met:
14
15 * Redistributions of source code must retain the above copyright notice,
16 this list of conditions and the following disclaimer.
17
18 * 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
22 * Neither the name of the University of Cambridge nor the names of its
23 contributors may be used to endorse or promote products derived from
24 this software without specific prior written permission.
25
26 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
27 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
30 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 POSSIBILITY OF SUCH DAMAGE.
37 -----------------------------------------------------------------------------
38 */
39
40
41 /* This module contains the external function pcre_study(), along with local
42 supporting functions. */
43
44
45 #ifdef HAVE_CONFIG_H
46 #include "config.h"
47 #endif
48
49 #include "pcre_internal.h"
50
51 #define SET_BIT(c) start_bits[c/8] |= (1 << (c&7))
52
53 /* Returns from set_start_bits() */
54
55 enum { SSB_FAIL, SSB_DONE, SSB_CONTINUE };
56
57
58
59 /*************************************************
60 * Find the minimum subject length for a group *
61 *************************************************/
62
63 /* Scan a parenthesized group and compute the minimum length of subject that
64 is needed to match it. This is a lower bound; it does not mean there is a
65 string of that length that matches. In UTF8 mode, the result is in characters
66 rather than bytes.
67
68 Arguments:
69 code pointer to start of group (the bracket)
70 startcode pointer to start of the whole pattern
71 options the compiling options
72
73 Returns: the minimum length
74 -1 if \C was encountered
75 -2 internal error (missing capturing bracket)
76 -3 internal error (opcode not listed)
77 */
78
79 static int
80 find_minlength(const uschar *code, const uschar *startcode, int options)
81 {
82 int length = -1;
83 BOOL utf8 = (options & PCRE_UTF8) != 0;
84 BOOL had_recurse = FALSE;
85 register int branchlength = 0;
86 register uschar *cc = (uschar *)code + 1 + LINK_SIZE;
87
88 if (*code == OP_CBRA || *code == OP_SCBRA ||
89 *code == OP_CBRAPOS || *code == OP_SCBRAPOS) cc += 2;
90
91 /* Scan along the opcodes for this branch. If we get to the end of the
92 branch, check the length against that of the other branches. */
93
94 for (;;)
95 {
96 int d, min;
97 uschar *cs, *ce;
98 register int op = *cc;
99
100 switch (op)
101 {
102 case OP_COND:
103 case OP_SCOND:
104
105 /* If there is only one branch in a condition, the implied branch has zero
106 length, so we don't add anything. This covers the DEFINE "condition"
107 automatically. */
108
109 cs = cc + GET(cc, 1);
110 if (*cs != OP_ALT)
111 {
112 cc = cs + 1 + LINK_SIZE;
113 break;
114 }
115
116 /* Otherwise we can fall through and treat it the same as any other
117 subpattern. */
118
119 case OP_CBRA:
120 case OP_SCBRA:
121 case OP_BRA:
122 case OP_SBRA:
123 case OP_CBRAPOS:
124 case OP_SCBRAPOS:
125 case OP_BRAPOS:
126 case OP_SBRAPOS:
127 case OP_ONCE:
128 d = find_minlength(cc, startcode, options);
129 if (d < 0) return d;
130 branchlength += d;
131 do cc += GET(cc, 1); while (*cc == OP_ALT);
132 cc += 1 + LINK_SIZE;
133 break;
134
135 /* Reached end of a branch; if it's a ket it is the end of a nested
136 call. If it's ALT it is an alternation in a nested call. If it is
137 END it's the end of the outer call. All can be handled by the same code. */
138
139 case OP_ALT:
140 case OP_KET:
141 case OP_KETRMAX:
142 case OP_KETRMIN:
143 case OP_KETRPOS:
144 case OP_END:
145 if (length < 0 || (!had_recurse && branchlength < length))
146 length = branchlength;
147 if (*cc != OP_ALT) return length;
148 cc += 1 + LINK_SIZE;
149 branchlength = 0;
150 had_recurse = FALSE;
151 break;
152
153 /* Skip over assertive subpatterns */
154
155 case OP_ASSERT:
156 case OP_ASSERT_NOT:
157 case OP_ASSERTBACK:
158 case OP_ASSERTBACK_NOT:
159 do cc += GET(cc, 1); while (*cc == OP_ALT);
160 /* Fall through */
161
162 /* Skip over things that don't match chars */
163
164 case OP_REVERSE:
165 case OP_CREF:
166 case OP_NCREF:
167 case OP_RREF:
168 case OP_NRREF:
169 case OP_DEF:
170 case OP_CALLOUT:
171 case OP_SOD:
172 case OP_SOM:
173 case OP_EOD:
174 case OP_EODN:
175 case OP_CIRC:
176 case OP_CIRCM:
177 case OP_DOLL:
178 case OP_DOLLM:
179 case OP_NOT_WORD_BOUNDARY:
180 case OP_WORD_BOUNDARY:
181 cc += _pcre_OP_lengths[*cc];
182 break;
183
184 /* Skip over a subpattern that has a {0} or {0,x} quantifier */
185
186 case OP_BRAZERO:
187 case OP_BRAMINZERO:
188 case OP_BRAPOSZERO:
189 case OP_SKIPZERO:
190 cc += _pcre_OP_lengths[*cc];
191 do cc += GET(cc, 1); while (*cc == OP_ALT);
192 cc += 1 + LINK_SIZE;
193 break;
194
195 /* Handle literal characters and + repetitions */
196
197 case OP_CHAR:
198 case OP_CHARI:
199 case OP_NOT:
200 case OP_NOTI:
201 case OP_PLUS:
202 case OP_PLUSI:
203 case OP_MINPLUS:
204 case OP_MINPLUSI:
205 case OP_POSPLUS:
206 case OP_POSPLUSI:
207 case OP_NOTPLUS:
208 case OP_NOTPLUSI:
209 case OP_NOTMINPLUS:
210 case OP_NOTMINPLUSI:
211 case OP_NOTPOSPLUS:
212 case OP_NOTPOSPLUSI:
213 branchlength++;
214 cc += 2;
215 #ifdef SUPPORT_UTF8
216 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
217 #endif
218 break;
219
220 case OP_TYPEPLUS:
221 case OP_TYPEMINPLUS:
222 case OP_TYPEPOSPLUS:
223 branchlength++;
224 cc += (cc[1] == OP_PROP || cc[1] == OP_NOTPROP)? 4 : 2;
225 break;
226
227 /* Handle exact repetitions. The count is already in characters, but we
228 need to skip over a multibyte character in UTF8 mode. */
229
230 case OP_EXACT:
231 case OP_EXACTI:
232 case OP_NOTEXACT:
233 case OP_NOTEXACTI:
234 branchlength += GET2(cc,1);
235 cc += 4;
236 #ifdef SUPPORT_UTF8
237 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
238 #endif
239 break;
240
241 case OP_TYPEEXACT:
242 branchlength += GET2(cc,1);
243 cc += (cc[3] == OP_PROP || cc[3] == OP_NOTPROP)? 6 : 4;
244 break;
245
246 /* Handle single-char non-literal matchers */
247
248 case OP_PROP:
249 case OP_NOTPROP:
250 cc += 2;
251 /* Fall through */
252
253 case OP_NOT_DIGIT:
254 case OP_DIGIT:
255 case OP_NOT_WHITESPACE:
256 case OP_WHITESPACE:
257 case OP_NOT_WORDCHAR:
258 case OP_WORDCHAR:
259 case OP_ANY:
260 case OP_ALLANY:
261 case OP_EXTUNI:
262 case OP_HSPACE:
263 case OP_NOT_HSPACE:
264 case OP_VSPACE:
265 case OP_NOT_VSPACE:
266 branchlength++;
267 cc++;
268 break;
269
270 /* "Any newline" might match two characters */
271
272 case OP_ANYNL:
273 branchlength += 2;
274 cc++;
275 break;
276
277 /* The single-byte matcher means we can't proceed in UTF-8 mode */
278
279 case OP_ANYBYTE:
280 #ifdef SUPPORT_UTF8
281 if (utf8) return -1;
282 #endif
283 branchlength++;
284 cc++;
285 break;
286
287 /* For repeated character types, we have to test for \p and \P, which have
288 an extra two bytes of parameters. */
289
290 case OP_TYPESTAR:
291 case OP_TYPEMINSTAR:
292 case OP_TYPEQUERY:
293 case OP_TYPEMINQUERY:
294 case OP_TYPEPOSSTAR:
295 case OP_TYPEPOSQUERY:
296 if (cc[1] == OP_PROP || cc[1] == OP_NOTPROP) cc += 2;
297 cc += _pcre_OP_lengths[op];
298 break;
299
300 case OP_TYPEUPTO:
301 case OP_TYPEMINUPTO:
302 case OP_TYPEPOSUPTO:
303 if (cc[3] == OP_PROP || cc[3] == OP_NOTPROP) cc += 2;
304 cc += _pcre_OP_lengths[op];
305 break;
306
307 /* Check a class for variable quantification */
308
309 #ifdef SUPPORT_UTF8
310 case OP_XCLASS:
311 cc += GET(cc, 1) - 33;
312 /* Fall through */
313 #endif
314
315 case OP_CLASS:
316 case OP_NCLASS:
317 cc += 33;
318
319 switch (*cc)
320 {
321 case OP_CRPLUS:
322 case OP_CRMINPLUS:
323 branchlength++;
324 /* Fall through */
325
326 case OP_CRSTAR:
327 case OP_CRMINSTAR:
328 case OP_CRQUERY:
329 case OP_CRMINQUERY:
330 cc++;
331 break;
332
333 case OP_CRRANGE:
334 case OP_CRMINRANGE:
335 branchlength += GET2(cc,1);
336 cc += 5;
337 break;
338
339 default:
340 branchlength++;
341 break;
342 }
343 break;
344
345 /* Backreferences and subroutine calls are treated in the same way: we find
346 the minimum length for the subpattern. A recursion, however, causes an
347 a flag to be set that causes the length of this branch to be ignored. The
348 logic is that a recursion can only make sense if there is another
349 alternation that stops the recursing. That will provide the minimum length
350 (when no recursion happens). A backreference within the group that it is
351 referencing behaves in the same way.
352
353 If PCRE_JAVASCRIPT_COMPAT is set, a backreference to an unset bracket
354 matches an empty string (by default it causes a matching failure), so in
355 that case we must set the minimum length to zero. */
356
357 case OP_REF:
358 case OP_REFI:
359 if ((options & PCRE_JAVASCRIPT_COMPAT) == 0)
360 {
361 ce = cs = (uschar *)_pcre_find_bracket(startcode, utf8, GET2(cc, 1));
362 if (cs == NULL) return -2;
363 do ce += GET(ce, 1); while (*ce == OP_ALT);
364 if (cc > cs && cc < ce)
365 {
366 d = 0;
367 had_recurse = TRUE;
368 }
369 else d = find_minlength(cs, startcode, options);
370 }
371 else d = 0;
372 cc += 3;
373
374 /* Handle repeated back references */
375
376 switch (*cc)
377 {
378 case OP_CRSTAR:
379 case OP_CRMINSTAR:
380 case OP_CRQUERY:
381 case OP_CRMINQUERY:
382 min = 0;
383 cc++;
384 break;
385
386 case OP_CRPLUS:
387 case OP_CRMINPLUS:
388 min = 1;
389 cc++;
390 break;
391
392 case OP_CRRANGE:
393 case OP_CRMINRANGE:
394 min = GET2(cc, 1);
395 cc += 5;
396 break;
397
398 default:
399 min = 1;
400 break;
401 }
402
403 branchlength += min * d;
404 break;
405
406 case OP_RECURSE:
407 cs = ce = (uschar *)startcode + GET(cc, 1);
408 if (cs == NULL) return -2;
409 do ce += GET(ce, 1); while (*ce == OP_ALT);
410 if (cc > cs && cc < ce)
411 had_recurse = TRUE;
412 else
413 branchlength += find_minlength(cs, startcode, options);
414 cc += 1 + LINK_SIZE;
415 break;
416
417 /* Anything else does not or need not match a character. We can get the
418 item's length from the table, but for those that can match zero occurrences
419 of a character, we must take special action for UTF-8 characters. As it
420 happens, the "NOT" versions of these opcodes are used at present only for
421 ASCII characters, so they could be omitted from this list. However, in
422 future that may change, so we include them here so as not to leave a
423 gotcha for a future maintainer. */
424
425 case OP_UPTO:
426 case OP_UPTOI:
427 case OP_NOTUPTO:
428 case OP_NOTUPTOI:
429 case OP_MINUPTO:
430 case OP_MINUPTOI:
431 case OP_NOTMINUPTO:
432 case OP_NOTMINUPTOI:
433 case OP_POSUPTO:
434 case OP_POSUPTOI:
435 case OP_NOTPOSUPTO:
436 case OP_NOTPOSUPTOI:
437
438 case OP_STAR:
439 case OP_STARI:
440 case OP_NOTSTAR:
441 case OP_NOTSTARI:
442 case OP_MINSTAR:
443 case OP_MINSTARI:
444 case OP_NOTMINSTAR:
445 case OP_NOTMINSTARI:
446 case OP_POSSTAR:
447 case OP_POSSTARI:
448 case OP_NOTPOSSTAR:
449 case OP_NOTPOSSTARI:
450
451 case OP_QUERY:
452 case OP_QUERYI:
453 case OP_NOTQUERY:
454 case OP_NOTQUERYI:
455 case OP_MINQUERY:
456 case OP_MINQUERYI:
457 case OP_NOTMINQUERY:
458 case OP_NOTMINQUERYI:
459 case OP_POSQUERY:
460 case OP_POSQUERYI:
461 case OP_NOTPOSQUERY:
462 case OP_NOTPOSQUERYI:
463
464 cc += _pcre_OP_lengths[op];
465 #ifdef SUPPORT_UTF8
466 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
467 #endif
468 break;
469
470 /* Skip these, but we need to add in the name length. */
471
472 case OP_MARK:
473 case OP_PRUNE_ARG:
474 case OP_SKIP_ARG:
475 cc += _pcre_OP_lengths[op] + cc[1];
476 break;
477
478 case OP_THEN_ARG:
479 cc += _pcre_OP_lengths[op] + cc[1+LINK_SIZE];
480 break;
481
482 /* The remaining opcodes are just skipped over. */
483
484 case OP_ACCEPT:
485 case OP_CLOSE:
486 case OP_COMMIT:
487 case OP_FAIL:
488 case OP_PRUNE:
489 case OP_SET_SOM:
490 case OP_SKIP:
491 case OP_THEN:
492 cc += _pcre_OP_lengths[op];
493 break;
494
495 /* This should not occur: we list all opcodes explicitly so that when
496 new ones get added they are properly considered. */
497
498 default:
499 return -3;
500 }
501 }
502 /* Control never gets here */
503 }
504
505
506
507 /*************************************************
508 * Set a bit and maybe its alternate case *
509 *************************************************/
510
511 /* Given a character, set its first byte's bit in the table, and also the
512 corresponding bit for the other version of a letter if we are caseless. In
513 UTF-8 mode, for characters greater than 127, we can only do the caseless thing
514 when Unicode property support is available.
515
516 Arguments:
517 start_bits points to the bit map
518 p points to the character
519 caseless the caseless flag
520 cd the block with char table pointers
521 utf8 TRUE for UTF-8 mode
522
523 Returns: pointer after the character
524 */
525
526 static const uschar *
527 set_table_bit(uschar *start_bits, const uschar *p, BOOL caseless,
528 compile_data *cd, BOOL utf8)
529 {
530 unsigned int c = *p;
531
532 SET_BIT(c);
533
534 #ifdef SUPPORT_UTF8
535 if (utf8 && c > 127)
536 {
537 GETCHARINC(c, p);
538 #ifdef SUPPORT_UCP
539 if (caseless)
540 {
541 uschar buff[8];
542 c = UCD_OTHERCASE(c);
543 (void)_pcre_ord2utf8(c, buff);
544 SET_BIT(buff[0]);
545 }
546 #endif
547 return p;
548 }
549 #endif
550
551 /* Not UTF-8 mode, or character is less than 127. */
552
553 if (caseless && (cd->ctypes[c] & ctype_letter) != 0) SET_BIT(cd->fcc[c]);
554 return p + 1;
555 }
556
557
558
559 /*************************************************
560 * Set bits for a positive character type *
561 *************************************************/
562
563 /* This function sets starting bits for a character type. In UTF-8 mode, we can
564 only do a direct setting for bytes less than 128, as otherwise there can be
565 confusion with bytes in the middle of UTF-8 characters. In a "traditional"
566 environment, the tables will only recognize ASCII characters anyway, but in at
567 least one Windows environment, some higher bytes bits were set in the tables.
568 So we deal with that case by considering the UTF-8 encoding.
569
570 Arguments:
571 start_bits the starting bitmap
572 cbit type the type of character wanted
573 table_limit 32 for non-UTF-8; 16 for UTF-8
574 cd the block with char table pointers
575
576 Returns: nothing
577 */
578
579 static void
580 set_type_bits(uschar *start_bits, int cbit_type, int table_limit,
581 compile_data *cd)
582 {
583 register int c;
584 for (c = 0; c < table_limit; c++) start_bits[c] |= cd->cbits[c+cbit_type];
585 if (table_limit == 32) return;
586 for (c = 128; c < 256; c++)
587 {
588 if ((cd->cbits[c/8] & (1 << (c&7))) != 0)
589 {
590 uschar buff[8];
591 (void)_pcre_ord2utf8(c, buff);
592 SET_BIT(buff[0]);
593 }
594 }
595 }
596
597
598 /*************************************************
599 * Set bits for a negative character type *
600 *************************************************/
601
602 /* This function sets starting bits for a negative character type such as \D.
603 In UTF-8 mode, we can only do a direct setting for bytes less than 128, as
604 otherwise there can be confusion with bytes in the middle of UTF-8 characters.
605 Unlike in the positive case, where we can set appropriate starting bits for
606 specific high-valued UTF-8 characters, in this case we have to set the bits for
607 all high-valued characters. The lowest is 0xc2, but we overkill by starting at
608 0xc0 (192) for simplicity.
609
610 Arguments:
611 start_bits the starting bitmap
612 cbit type the type of character wanted
613 table_limit 32 for non-UTF-8; 16 for UTF-8
614 cd the block with char table pointers
615
616 Returns: nothing
617 */
618
619 static void
620 set_nottype_bits(uschar *start_bits, int cbit_type, int table_limit,
621 compile_data *cd)
622 {
623 register int c;
624 for (c = 0; c < table_limit; c++) start_bits[c] |= ~cd->cbits[c+cbit_type];
625 if (table_limit != 32) for (c = 24; c < 32; c++) start_bits[c] = 0xff;
626 }
627
628
629
630 /*************************************************
631 * Create bitmap of starting bytes *
632 *************************************************/
633
634 /* This function scans a compiled unanchored expression recursively and
635 attempts to build a bitmap of the set of possible starting bytes. As time goes
636 by, we may be able to get more clever at doing this. The SSB_CONTINUE return is
637 useful for parenthesized groups in patterns such as (a*)b where the group
638 provides some optional starting bytes but scanning must continue at the outer
639 level to find at least one mandatory byte. At the outermost level, this
640 function fails unless the result is SSB_DONE.
641
642 Arguments:
643 code points to an expression
644 start_bits points to a 32-byte table, initialized to 0
645 utf8 TRUE if in UTF-8 mode
646 cd the block with char table pointers
647
648 Returns: SSB_FAIL => Failed to find any starting bytes
649 SSB_DONE => Found mandatory starting bytes
650 SSB_CONTINUE => Found optional starting bytes
651 */
652
653 static int
654 set_start_bits(const uschar *code, uschar *start_bits, BOOL utf8,
655 compile_data *cd)
656 {
657 register int c;
658 int yield = SSB_DONE;
659 int table_limit = utf8? 16:32;
660
661 #if 0
662 /* ========================================================================= */
663 /* The following comment and code was inserted in January 1999. In May 2006,
664 when it was observed to cause compiler warnings about unused values, I took it
665 out again. If anybody is still using OS/2, they will have to put it back
666 manually. */
667
668 /* This next statement and the later reference to dummy are here in order to
669 trick the optimizer of the IBM C compiler for OS/2 into generating correct
670 code. Apparently IBM isn't going to fix the problem, and we would rather not
671 disable optimization (in this module it actually makes a big difference, and
672 the pcre module can use all the optimization it can get). */
673
674 volatile int dummy;
675 /* ========================================================================= */
676 #endif
677
678 do
679 {
680 BOOL try_next = TRUE;
681 const uschar *tcode = code + 1 + LINK_SIZE;
682
683 if (*code == OP_CBRA || *code == OP_SCBRA ||
684 *code == OP_CBRAPOS || *code == OP_SCBRAPOS) tcode += 2;
685
686 while (try_next) /* Loop for items in this branch */
687 {
688 int rc;
689 switch(*tcode)
690 {
691 /* Fail if we reach something we don't understand */
692
693 default:
694 return SSB_FAIL;
695
696 /* If we hit a bracket or a positive lookahead assertion, recurse to set
697 bits from within the subpattern. If it can't find anything, we have to
698 give up. If it finds some mandatory character(s), we are done for this
699 branch. Otherwise, carry on scanning after the subpattern. */
700
701 case OP_BRA:
702 case OP_SBRA:
703 case OP_CBRA:
704 case OP_SCBRA:
705 case OP_BRAPOS:
706 case OP_SBRAPOS:
707 case OP_CBRAPOS:
708 case OP_SCBRAPOS:
709 case OP_ONCE:
710 case OP_ASSERT:
711 rc = set_start_bits(tcode, start_bits, utf8, cd);
712 if (rc == SSB_FAIL) return SSB_FAIL;
713 if (rc == SSB_DONE) try_next = FALSE; else
714 {
715 do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
716 tcode += 1 + LINK_SIZE;
717 }
718 break;
719
720 /* If we hit ALT or KET, it means we haven't found anything mandatory in
721 this branch, though we might have found something optional. For ALT, we
722 continue with the next alternative, but we have to arrange that the final
723 result from subpattern is SSB_CONTINUE rather than SSB_DONE. For KET,
724 return SSB_CONTINUE: if this is the top level, that indicates failure,
725 but after a nested subpattern, it causes scanning to continue. */
726
727 case OP_ALT:
728 yield = SSB_CONTINUE;
729 try_next = FALSE;
730 break;
731
732 case OP_KET:
733 case OP_KETRMAX:
734 case OP_KETRMIN:
735 case OP_KETRPOS:
736 return SSB_CONTINUE;
737
738 /* Skip over callout */
739
740 case OP_CALLOUT:
741 tcode += 2 + 2*LINK_SIZE;
742 break;
743
744 /* Skip over lookbehind and negative lookahead assertions */
745
746 case OP_ASSERT_NOT:
747 case OP_ASSERTBACK:
748 case OP_ASSERTBACK_NOT:
749 do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
750 tcode += 1 + LINK_SIZE;
751 break;
752
753 /* BRAZERO does the bracket, but carries on. */
754
755 case OP_BRAZERO:
756 case OP_BRAMINZERO:
757 case OP_BRAPOSZERO:
758 if (set_start_bits(++tcode, start_bits, utf8, cd) == SSB_FAIL)
759 return SSB_FAIL;
760 /* =========================================================================
761 See the comment at the head of this function concerning the next line,
762 which was an old fudge for the benefit of OS/2.
763 dummy = 1;
764 ========================================================================= */
765 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
766 tcode += 1 + LINK_SIZE;
767 break;
768
769 /* SKIPZERO skips the bracket. */
770
771 case OP_SKIPZERO:
772 tcode++;
773 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
774 tcode += 1 + LINK_SIZE;
775 break;
776
777 /* Single-char * or ? sets the bit and tries the next item */
778
779 case OP_STAR:
780 case OP_MINSTAR:
781 case OP_POSSTAR:
782 case OP_QUERY:
783 case OP_MINQUERY:
784 case OP_POSQUERY:
785 tcode = set_table_bit(start_bits, tcode + 1, FALSE, cd, utf8);
786 break;
787
788 case OP_STARI:
789 case OP_MINSTARI:
790 case OP_POSSTARI:
791 case OP_QUERYI:
792 case OP_MINQUERYI:
793 case OP_POSQUERYI:
794 tcode = set_table_bit(start_bits, tcode + 1, TRUE, cd, utf8);
795 break;
796
797 /* Single-char upto sets the bit and tries the next */
798
799 case OP_UPTO:
800 case OP_MINUPTO:
801 case OP_POSUPTO:
802 tcode = set_table_bit(start_bits, tcode + 3, FALSE, cd, utf8);
803 break;
804
805 case OP_UPTOI:
806 case OP_MINUPTOI:
807 case OP_POSUPTOI:
808 tcode = set_table_bit(start_bits, tcode + 3, TRUE, cd, utf8);
809 break;
810
811 /* At least one single char sets the bit and stops */
812
813 case OP_EXACT:
814 tcode += 2;
815 /* Fall through */
816 case OP_CHAR:
817 case OP_PLUS:
818 case OP_MINPLUS:
819 case OP_POSPLUS:
820 (void)set_table_bit(start_bits, tcode + 1, FALSE, cd, utf8);
821 try_next = FALSE;
822 break;
823
824 case OP_EXACTI:
825 tcode += 2;
826 /* Fall through */
827 case OP_CHARI:
828 case OP_PLUSI:
829 case OP_MINPLUSI:
830 case OP_POSPLUSI:
831 (void)set_table_bit(start_bits, tcode + 1, TRUE, cd, utf8);
832 try_next = FALSE;
833 break;
834
835 /* Special spacing and line-terminating items. These recognize specific
836 lists of characters. The difference between VSPACE and ANYNL is that the
837 latter can match the two-character CRLF sequence, but that is not
838 relevant for finding the first character, so their code here is
839 identical. */
840
841 case OP_HSPACE:
842 SET_BIT(0x09);
843 SET_BIT(0x20);
844 if (utf8)
845 {
846 SET_BIT(0xC2); /* For U+00A0 */
847 SET_BIT(0xE1); /* For U+1680, U+180E */
848 SET_BIT(0xE2); /* For U+2000 - U+200A, U+202F, U+205F */
849 SET_BIT(0xE3); /* For U+3000 */
850 }
851 else SET_BIT(0xA0);
852 try_next = FALSE;
853 break;
854
855 case OP_ANYNL:
856 case OP_VSPACE:
857 SET_BIT(0x0A);
858 SET_BIT(0x0B);
859 SET_BIT(0x0C);
860 SET_BIT(0x0D);
861 if (utf8)
862 {
863 SET_BIT(0xC2); /* For U+0085 */
864 SET_BIT(0xE2); /* For U+2028, U+2029 */
865 }
866 else SET_BIT(0x85);
867 try_next = FALSE;
868 break;
869
870 /* Single character types set the bits and stop. Note that if PCRE_UCP
871 is set, we do not see these op codes because \d etc are converted to
872 properties. Therefore, these apply in the case when only characters less
873 than 256 are recognized to match the types. */
874
875 case OP_NOT_DIGIT:
876 set_nottype_bits(start_bits, cbit_digit, table_limit, cd);
877 try_next = FALSE;
878 break;
879
880 case OP_DIGIT:
881 set_type_bits(start_bits, cbit_digit, table_limit, cd);
882 try_next = FALSE;
883 break;
884
885 /* The cbit_space table has vertical tab as whitespace; we have to
886 ensure it is set as not whitespace. */
887
888 case OP_NOT_WHITESPACE:
889 set_nottype_bits(start_bits, cbit_space, table_limit, cd);
890 start_bits[1] |= 0x08;
891 try_next = FALSE;
892 break;
893
894 /* The cbit_space table has vertical tab as whitespace; we have to
895 not set it from the table. */
896
897 case OP_WHITESPACE:
898 c = start_bits[1]; /* Save in case it was already set */
899 set_type_bits(start_bits, cbit_space, table_limit, cd);
900 start_bits[1] = (start_bits[1] & ~0x08) | c;
901 try_next = FALSE;
902 break;
903
904 case OP_NOT_WORDCHAR:
905 set_nottype_bits(start_bits, cbit_word, table_limit, cd);
906 try_next = FALSE;
907 break;
908
909 case OP_WORDCHAR:
910 set_type_bits(start_bits, cbit_word, table_limit, cd);
911 try_next = FALSE;
912 break;
913
914 /* One or more character type fudges the pointer and restarts, knowing
915 it will hit a single character type and stop there. */
916
917 case OP_TYPEPLUS:
918 case OP_TYPEMINPLUS:
919 case OP_TYPEPOSPLUS:
920 tcode++;
921 break;
922
923 case OP_TYPEEXACT:
924 tcode += 3;
925 break;
926
927 /* Zero or more repeats of character types set the bits and then
928 try again. */
929
930 case OP_TYPEUPTO:
931 case OP_TYPEMINUPTO:
932 case OP_TYPEPOSUPTO:
933 tcode += 2; /* Fall through */
934
935 case OP_TYPESTAR:
936 case OP_TYPEMINSTAR:
937 case OP_TYPEPOSSTAR:
938 case OP_TYPEQUERY:
939 case OP_TYPEMINQUERY:
940 case OP_TYPEPOSQUERY:
941 switch(tcode[1])
942 {
943 default:
944 case OP_ANY:
945 case OP_ALLANY:
946 return SSB_FAIL;
947
948 case OP_HSPACE:
949 SET_BIT(0x09);
950 SET_BIT(0x20);
951 if (utf8)
952 {
953 SET_BIT(0xC2); /* For U+00A0 */
954 SET_BIT(0xE1); /* For U+1680, U+180E */
955 SET_BIT(0xE2); /* For U+2000 - U+200A, U+202F, U+205F */
956 SET_BIT(0xE3); /* For U+3000 */
957 }
958 else SET_BIT(0xA0);
959 break;
960
961 case OP_ANYNL:
962 case OP_VSPACE:
963 SET_BIT(0x0A);
964 SET_BIT(0x0B);
965 SET_BIT(0x0C);
966 SET_BIT(0x0D);
967 if (utf8)
968 {
969 SET_BIT(0xC2); /* For U+0085 */
970 SET_BIT(0xE2); /* For U+2028, U+2029 */
971 }
972 else SET_BIT(0x85);
973 break;
974
975 case OP_NOT_DIGIT:
976 set_nottype_bits(start_bits, cbit_digit, table_limit, cd);
977 break;
978
979 case OP_DIGIT:
980 set_type_bits(start_bits, cbit_digit, table_limit, cd);
981 break;
982
983 /* The cbit_space table has vertical tab as whitespace; we have to
984 ensure it gets set as not whitespace. */
985
986 case OP_NOT_WHITESPACE:
987 set_nottype_bits(start_bits, cbit_space, table_limit, cd);
988 start_bits[1] |= 0x08;
989 break;
990
991 /* The cbit_space table has vertical tab as whitespace; we have to
992 avoid setting it. */
993
994 case OP_WHITESPACE:
995 c = start_bits[1]; /* Save in case it was already set */
996 set_type_bits(start_bits, cbit_space, table_limit, cd);
997 start_bits[1] = (start_bits[1] & ~0x08) | c;
998 break;
999
1000 case OP_NOT_WORDCHAR:
1001 set_nottype_bits(start_bits, cbit_word, table_limit, cd);
1002 break;
1003
1004 case OP_WORDCHAR:
1005 set_type_bits(start_bits, cbit_word, table_limit, cd);
1006 break;
1007 }
1008
1009 tcode += 2;
1010 break;
1011
1012 /* Character class where all the information is in a bit map: set the
1013 bits and either carry on or not, according to the repeat count. If it was
1014 a negative class, and we are operating with UTF-8 characters, any byte
1015 with a value >= 0xc4 is a potentially valid starter because it starts a
1016 character with a value > 255. */
1017
1018 case OP_NCLASS:
1019 #ifdef SUPPORT_UTF8
1020 if (utf8)
1021 {
1022 start_bits[24] |= 0xf0; /* Bits for 0xc4 - 0xc8 */
1023 memset(start_bits+25, 0xff, 7); /* Bits for 0xc9 - 0xff */
1024 }
1025 #endif
1026 /* Fall through */
1027
1028 case OP_CLASS:
1029 {
1030 tcode++;
1031
1032 /* In UTF-8 mode, the bits in a bit map correspond to character
1033 values, not to byte values. However, the bit map we are constructing is
1034 for byte values. So we have to do a conversion for characters whose
1035 value is > 127. In fact, there are only two possible starting bytes for
1036 characters in the range 128 - 255. */
1037
1038 #ifdef SUPPORT_UTF8
1039 if (utf8)
1040 {
1041 for (c = 0; c < 16; c++) start_bits[c] |= tcode[c];
1042 for (c = 128; c < 256; c++)
1043 {
1044 if ((tcode[c/8] && (1 << (c&7))) != 0)
1045 {
1046 int d = (c >> 6) | 0xc0; /* Set bit for this starter */
1047 start_bits[d/8] |= (1 << (d&7)); /* and then skip on to the */
1048 c = (c & 0xc0) + 0x40 - 1; /* next relevant character. */
1049 }
1050 }
1051 }
1052
1053 /* In non-UTF-8 mode, the two bit maps are completely compatible. */
1054
1055 else
1056 #endif
1057 {
1058 for (c = 0; c < 32; c++) start_bits[c] |= tcode[c];
1059 }
1060
1061 /* Advance past the bit map, and act on what follows */
1062
1063 tcode += 32;
1064 switch (*tcode)
1065 {
1066 case OP_CRSTAR:
1067 case OP_CRMINSTAR:
1068 case OP_CRQUERY:
1069 case OP_CRMINQUERY:
1070 tcode++;
1071 break;
1072
1073 case OP_CRRANGE:
1074 case OP_CRMINRANGE:
1075 if (((tcode[1] << 8) + tcode[2]) == 0) tcode += 5;
1076 else try_next = FALSE;
1077 break;
1078
1079 default:
1080 try_next = FALSE;
1081 break;
1082 }
1083 }
1084 break; /* End of bitmap class handling */
1085
1086 } /* End of switch */
1087 } /* End of try_next loop */
1088
1089 code += GET(code, 1); /* Advance to next branch */
1090 }
1091 while (*code == OP_ALT);
1092 return yield;
1093 }
1094
1095
1096
1097 /*************************************************
1098 * Study a compiled expression *
1099 *************************************************/
1100
1101 /* This function is handed a compiled expression that it must study to produce
1102 information that will speed up the matching. It returns a pcre_extra block
1103 which then gets handed back to pcre_exec().
1104
1105 Arguments:
1106 re points to the compiled expression
1107 options contains option bits
1108 errorptr points to where to place error messages;
1109 set NULL unless error
1110
1111 Returns: pointer to a pcre_extra block, with study_data filled in and the
1112 appropriate flags set;
1113 NULL on error or if no optimization possible
1114 */
1115
1116 PCRE_EXP_DEFN pcre_extra * PCRE_CALL_CONVENTION
1117 pcre_study(const pcre *external_re, int options, const char **errorptr)
1118 {
1119 int min;
1120 BOOL bits_set = FALSE;
1121 uschar start_bits[32];
1122 pcre_extra *extra;
1123 pcre_study_data *study;
1124 const uschar *tables;
1125 uschar *code;
1126 compile_data compile_block;
1127 const real_pcre *re = (const real_pcre *)external_re;
1128
1129 *errorptr = NULL;
1130
1131 if (re == NULL || re->magic_number != MAGIC_NUMBER)
1132 {
1133 *errorptr = "argument is not a compiled regular expression";
1134 return NULL;
1135 }
1136
1137 if ((options & ~PUBLIC_STUDY_OPTIONS) != 0)
1138 {
1139 *errorptr = "unknown or incorrect option bit(s) set";
1140 return NULL;
1141 }
1142
1143 code = (uschar *)re + re->name_table_offset +
1144 (re->name_count * re->name_entry_size);
1145
1146 /* For an anchored pattern, or an unanchored pattern that has a first char, or
1147 a multiline pattern that matches only at "line starts", there is no point in
1148 seeking a list of starting bytes. */
1149
1150 if ((re->options & PCRE_ANCHORED) == 0 &&
1151 (re->flags & (PCRE_FIRSTSET|PCRE_STARTLINE)) == 0)
1152 {
1153 /* Set the character tables in the block that is passed around */
1154
1155 tables = re->tables;
1156 if (tables == NULL)
1157 (void)pcre_fullinfo(external_re, NULL, PCRE_INFO_DEFAULT_TABLES,
1158 (void *)(&tables));
1159
1160 compile_block.lcc = tables + lcc_offset;
1161 compile_block.fcc = tables + fcc_offset;
1162 compile_block.cbits = tables + cbits_offset;
1163 compile_block.ctypes = tables + ctypes_offset;
1164
1165 /* See if we can find a fixed set of initial characters for the pattern. */
1166
1167 memset(start_bits, 0, 32 * sizeof(uschar));
1168 bits_set = set_start_bits(code, start_bits, (re->options & PCRE_UTF8) != 0,
1169 &compile_block) == SSB_DONE;
1170 }
1171
1172 /* Find the minimum length of subject string. */
1173
1174 switch(min = find_minlength(code, code, re->options))
1175 {
1176 case -2: *errorptr = "internal error: missing capturing bracket"; break;
1177 case -3: *errorptr = "internal error: opcode not recognized"; break;
1178 default: break;
1179 }
1180
1181 /* Return NULL if no optimization is possible. */
1182
1183 if (!bits_set && min < 0) return NULL;
1184
1185 /* Get a pcre_extra block and a pcre_study_data block. The study data is put in
1186 the latter, which is pointed to by the former, which may also get additional
1187 data set later by the calling program. At the moment, the size of
1188 pcre_study_data is fixed. We nevertheless save it in a field for returning via
1189 the pcre_fullinfo() function so that if it becomes variable in the future, we
1190 don't have to change that code. */
1191
1192 extra = (pcre_extra *)(pcre_malloc)
1193 (sizeof(pcre_extra) + sizeof(pcre_study_data));
1194
1195 if (extra == NULL)
1196 {
1197 *errorptr = "failed to get memory";
1198 return NULL;
1199 }
1200
1201 study = (pcre_study_data *)((char *)extra + sizeof(pcre_extra));
1202 extra->flags = PCRE_EXTRA_STUDY_DATA;
1203 extra->study_data = study;
1204
1205 study->size = sizeof(pcre_study_data);
1206 study->flags = 0;
1207
1208 if (bits_set)
1209 {
1210 study->flags |= PCRE_STUDY_MAPPED;
1211 memcpy(study->start_bits, start_bits, sizeof(start_bits));
1212 }
1213
1214 if (min >= 0)
1215 {
1216 study->flags |= PCRE_STUDY_MINLEN;
1217 study->minlength = min;
1218 }
1219
1220 return extra;
1221 }
1222
1223 /* End of pcre_study.c */

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