/[pcre]/code/trunk/pcre_study.c
ViewVC logotype

Contents of /code/trunk/pcre_study.c

Parent Directory Parent Directory | Revision Log Revision Log


Revision 605 - (show annotations)
Fri Jun 3 18:18:30 2011 UTC (4 years ago) by ph10
File MIME type: text/plain
File size: 36668 byte(s)
Error occurred while calculating annotation data.
Make pcre_study() more robust against update omissions; fix ONCE oversight.
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, SSB_UNKNOWN };
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 SSB_UNKNOWN => Hit an unrecognized opcode
652 */
653
654 static int
655 set_start_bits(const uschar *code, uschar *start_bits, BOOL utf8,
656 compile_data *cd)
657 {
658 register int c;
659 int yield = SSB_DONE;
660 int table_limit = utf8? 16:32;
661
662 #if 0
663 /* ========================================================================= */
664 /* The following comment and code was inserted in January 1999. In May 2006,
665 when it was observed to cause compiler warnings about unused values, I took it
666 out again. If anybody is still using OS/2, they will have to put it back
667 manually. */
668
669 /* This next statement and the later reference to dummy are here in order to
670 trick the optimizer of the IBM C compiler for OS/2 into generating correct
671 code. Apparently IBM isn't going to fix the problem, and we would rather not
672 disable optimization (in this module it actually makes a big difference, and
673 the pcre module can use all the optimization it can get). */
674
675 volatile int dummy;
676 /* ========================================================================= */
677 #endif
678
679 do
680 {
681 BOOL try_next = TRUE;
682 const uschar *tcode = code + 1 + LINK_SIZE;
683
684 if (*code == OP_CBRA || *code == OP_SCBRA ||
685 *code == OP_CBRAPOS || *code == OP_SCBRAPOS) tcode += 2;
686
687 while (try_next) /* Loop for items in this branch */
688 {
689 int rc;
690 switch(*tcode)
691 {
692 /* If we reach something we don't understand, it means a new opcode has
693 been created that hasn't been added to this code. Hopefully this problem
694 will be discovered during testing. */
695
696 default:
697 return SSB_UNKNOWN;
698
699 /* Fail for a valid opcode that implies no starting bits. */
700
701 case OP_ACCEPT:
702 case OP_ALLANY:
703 case OP_ANY:
704 case OP_ANYBYTE:
705 case OP_CIRC:
706 case OP_CIRCM:
707 case OP_CLOSE:
708 case OP_COMMIT:
709 case OP_COND:
710 case OP_CREF:
711 case OP_DEF:
712 case OP_DOLL:
713 case OP_DOLLM:
714 case OP_END:
715 case OP_EOD:
716 case OP_EODN:
717 case OP_EXTUNI:
718 case OP_FAIL:
719 case OP_MARK:
720 case OP_NCREF:
721 case OP_NOT:
722 case OP_NOTEXACT:
723 case OP_NOTEXACTI:
724 case OP_NOTI:
725 case OP_NOTMINPLUS:
726 case OP_NOTMINPLUSI:
727 case OP_NOTMINQUERY:
728 case OP_NOTMINQUERYI:
729 case OP_NOTMINSTAR:
730 case OP_NOTMINSTARI:
731 case OP_NOTMINUPTO:
732 case OP_NOTMINUPTOI:
733 case OP_NOTPLUS:
734 case OP_NOTPLUSI:
735 case OP_NOTPOSPLUS:
736 case OP_NOTPOSPLUSI:
737 case OP_NOTPOSQUERY:
738 case OP_NOTPOSQUERYI:
739 case OP_NOTPOSSTAR:
740 case OP_NOTPOSSTARI:
741 case OP_NOTPOSUPTO:
742 case OP_NOTPOSUPTOI:
743 case OP_NOTPROP:
744 case OP_NOTQUERY:
745 case OP_NOTQUERYI:
746 case OP_NOTSTAR:
747 case OP_NOTSTARI:
748 case OP_NOTUPTO:
749 case OP_NOTUPTOI:
750 case OP_NOT_HSPACE:
751 case OP_NOT_VSPACE:
752 case OP_NOT_WORD_BOUNDARY:
753 case OP_NRREF:
754 case OP_PROP:
755 case OP_PRUNE:
756 case OP_PRUNE_ARG:
757 case OP_RECURSE:
758 case OP_REF:
759 case OP_REFI:
760 case OP_REVERSE:
761 case OP_RREF:
762 case OP_SCOND:
763 case OP_SET_SOM:
764 case OP_SKIP:
765 case OP_SKIP_ARG:
766 case OP_SOD:
767 case OP_SOM:
768 case OP_THEN:
769 case OP_THEN_ARG:
770 case OP_WORD_BOUNDARY:
771 case OP_XCLASS:
772 return SSB_FAIL;
773
774 /* If we hit a bracket or a positive lookahead assertion, recurse to set
775 bits from within the subpattern. If it can't find anything, we have to
776 give up. If it finds some mandatory character(s), we are done for this
777 branch. Otherwise, carry on scanning after the subpattern. */
778
779 case OP_BRA:
780 case OP_SBRA:
781 case OP_CBRA:
782 case OP_SCBRA:
783 case OP_BRAPOS:
784 case OP_SBRAPOS:
785 case OP_CBRAPOS:
786 case OP_SCBRAPOS:
787 case OP_ONCE:
788 case OP_ASSERT:
789 rc = set_start_bits(tcode, start_bits, utf8, cd);
790 if (rc == SSB_FAIL || rc == SSB_UNKNOWN) return rc;
791 if (rc == SSB_DONE) try_next = FALSE; else
792 {
793 do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
794 tcode += 1 + LINK_SIZE;
795 }
796 break;
797
798 /* If we hit ALT or KET, it means we haven't found anything mandatory in
799 this branch, though we might have found something optional. For ALT, we
800 continue with the next alternative, but we have to arrange that the final
801 result from subpattern is SSB_CONTINUE rather than SSB_DONE. For KET,
802 return SSB_CONTINUE: if this is the top level, that indicates failure,
803 but after a nested subpattern, it causes scanning to continue. */
804
805 case OP_ALT:
806 yield = SSB_CONTINUE;
807 try_next = FALSE;
808 break;
809
810 case OP_KET:
811 case OP_KETRMAX:
812 case OP_KETRMIN:
813 case OP_KETRPOS:
814 return SSB_CONTINUE;
815
816 /* Skip over callout */
817
818 case OP_CALLOUT:
819 tcode += 2 + 2*LINK_SIZE;
820 break;
821
822 /* Skip over lookbehind and negative lookahead assertions */
823
824 case OP_ASSERT_NOT:
825 case OP_ASSERTBACK:
826 case OP_ASSERTBACK_NOT:
827 do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
828 tcode += 1 + LINK_SIZE;
829 break;
830
831 /* BRAZERO does the bracket, but carries on. */
832
833 case OP_BRAZERO:
834 case OP_BRAMINZERO:
835 case OP_BRAPOSZERO:
836 rc = set_start_bits(++tcode, start_bits, utf8, cd);
837 if (rc == SSB_FAIL || rc == SSB_UNKNOWN) return rc;
838 /* =========================================================================
839 See the comment at the head of this function concerning the next line,
840 which was an old fudge for the benefit of OS/2.
841 dummy = 1;
842 ========================================================================= */
843 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
844 tcode += 1 + LINK_SIZE;
845 break;
846
847 /* SKIPZERO skips the bracket. */
848
849 case OP_SKIPZERO:
850 tcode++;
851 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
852 tcode += 1 + LINK_SIZE;
853 break;
854
855 /* Single-char * or ? sets the bit and tries the next item */
856
857 case OP_STAR:
858 case OP_MINSTAR:
859 case OP_POSSTAR:
860 case OP_QUERY:
861 case OP_MINQUERY:
862 case OP_POSQUERY:
863 tcode = set_table_bit(start_bits, tcode + 1, FALSE, cd, utf8);
864 break;
865
866 case OP_STARI:
867 case OP_MINSTARI:
868 case OP_POSSTARI:
869 case OP_QUERYI:
870 case OP_MINQUERYI:
871 case OP_POSQUERYI:
872 tcode = set_table_bit(start_bits, tcode + 1, TRUE, cd, utf8);
873 break;
874
875 /* Single-char upto sets the bit and tries the next */
876
877 case OP_UPTO:
878 case OP_MINUPTO:
879 case OP_POSUPTO:
880 tcode = set_table_bit(start_bits, tcode + 3, FALSE, cd, utf8);
881 break;
882
883 case OP_UPTOI:
884 case OP_MINUPTOI:
885 case OP_POSUPTOI:
886 tcode = set_table_bit(start_bits, tcode + 3, TRUE, cd, utf8);
887 break;
888
889 /* At least one single char sets the bit and stops */
890
891 case OP_EXACT:
892 tcode += 2;
893 /* Fall through */
894 case OP_CHAR:
895 case OP_PLUS:
896 case OP_MINPLUS:
897 case OP_POSPLUS:
898 (void)set_table_bit(start_bits, tcode + 1, FALSE, cd, utf8);
899 try_next = FALSE;
900 break;
901
902 case OP_EXACTI:
903 tcode += 2;
904 /* Fall through */
905 case OP_CHARI:
906 case OP_PLUSI:
907 case OP_MINPLUSI:
908 case OP_POSPLUSI:
909 (void)set_table_bit(start_bits, tcode + 1, TRUE, cd, utf8);
910 try_next = FALSE;
911 break;
912
913 /* Special spacing and line-terminating items. These recognize specific
914 lists of characters. The difference between VSPACE and ANYNL is that the
915 latter can match the two-character CRLF sequence, but that is not
916 relevant for finding the first character, so their code here is
917 identical. */
918
919 case OP_HSPACE:
920 SET_BIT(0x09);
921 SET_BIT(0x20);
922 if (utf8)
923 {
924 SET_BIT(0xC2); /* For U+00A0 */
925 SET_BIT(0xE1); /* For U+1680, U+180E */
926 SET_BIT(0xE2); /* For U+2000 - U+200A, U+202F, U+205F */
927 SET_BIT(0xE3); /* For U+3000 */
928 }
929 else SET_BIT(0xA0);
930 try_next = FALSE;
931 break;
932
933 case OP_ANYNL:
934 case OP_VSPACE:
935 SET_BIT(0x0A);
936 SET_BIT(0x0B);
937 SET_BIT(0x0C);
938 SET_BIT(0x0D);
939 if (utf8)
940 {
941 SET_BIT(0xC2); /* For U+0085 */
942 SET_BIT(0xE2); /* For U+2028, U+2029 */
943 }
944 else SET_BIT(0x85);
945 try_next = FALSE;
946 break;
947
948 /* Single character types set the bits and stop. Note that if PCRE_UCP
949 is set, we do not see these op codes because \d etc are converted to
950 properties. Therefore, these apply in the case when only characters less
951 than 256 are recognized to match the types. */
952
953 case OP_NOT_DIGIT:
954 set_nottype_bits(start_bits, cbit_digit, table_limit, cd);
955 try_next = FALSE;
956 break;
957
958 case OP_DIGIT:
959 set_type_bits(start_bits, cbit_digit, table_limit, cd);
960 try_next = FALSE;
961 break;
962
963 /* The cbit_space table has vertical tab as whitespace; we have to
964 ensure it is set as not whitespace. */
965
966 case OP_NOT_WHITESPACE:
967 set_nottype_bits(start_bits, cbit_space, table_limit, cd);
968 start_bits[1] |= 0x08;
969 try_next = FALSE;
970 break;
971
972 /* The cbit_space table has vertical tab as whitespace; we have to
973 not set it from the table. */
974
975 case OP_WHITESPACE:
976 c = start_bits[1]; /* Save in case it was already set */
977 set_type_bits(start_bits, cbit_space, table_limit, cd);
978 start_bits[1] = (start_bits[1] & ~0x08) | c;
979 try_next = FALSE;
980 break;
981
982 case OP_NOT_WORDCHAR:
983 set_nottype_bits(start_bits, cbit_word, table_limit, cd);
984 try_next = FALSE;
985 break;
986
987 case OP_WORDCHAR:
988 set_type_bits(start_bits, cbit_word, table_limit, cd);
989 try_next = FALSE;
990 break;
991
992 /* One or more character type fudges the pointer and restarts, knowing
993 it will hit a single character type and stop there. */
994
995 case OP_TYPEPLUS:
996 case OP_TYPEMINPLUS:
997 case OP_TYPEPOSPLUS:
998 tcode++;
999 break;
1000
1001 case OP_TYPEEXACT:
1002 tcode += 3;
1003 break;
1004
1005 /* Zero or more repeats of character types set the bits and then
1006 try again. */
1007
1008 case OP_TYPEUPTO:
1009 case OP_TYPEMINUPTO:
1010 case OP_TYPEPOSUPTO:
1011 tcode += 2; /* Fall through */
1012
1013 case OP_TYPESTAR:
1014 case OP_TYPEMINSTAR:
1015 case OP_TYPEPOSSTAR:
1016 case OP_TYPEQUERY:
1017 case OP_TYPEMINQUERY:
1018 case OP_TYPEPOSQUERY:
1019 switch(tcode[1])
1020 {
1021 default:
1022 case OP_ANY:
1023 case OP_ALLANY:
1024 return SSB_FAIL;
1025
1026 case OP_HSPACE:
1027 SET_BIT(0x09);
1028 SET_BIT(0x20);
1029 if (utf8)
1030 {
1031 SET_BIT(0xC2); /* For U+00A0 */
1032 SET_BIT(0xE1); /* For U+1680, U+180E */
1033 SET_BIT(0xE2); /* For U+2000 - U+200A, U+202F, U+205F */
1034 SET_BIT(0xE3); /* For U+3000 */
1035 }
1036 else SET_BIT(0xA0);
1037 break;
1038
1039 case OP_ANYNL:
1040 case OP_VSPACE:
1041 SET_BIT(0x0A);
1042 SET_BIT(0x0B);
1043 SET_BIT(0x0C);
1044 SET_BIT(0x0D);
1045 if (utf8)
1046 {
1047 SET_BIT(0xC2); /* For U+0085 */
1048 SET_BIT(0xE2); /* For U+2028, U+2029 */
1049 }
1050 else SET_BIT(0x85);
1051 break;
1052
1053 case OP_NOT_DIGIT:
1054 set_nottype_bits(start_bits, cbit_digit, table_limit, cd);
1055 break;
1056
1057 case OP_DIGIT:
1058 set_type_bits(start_bits, cbit_digit, table_limit, cd);
1059 break;
1060
1061 /* The cbit_space table has vertical tab as whitespace; we have to
1062 ensure it gets set as not whitespace. */
1063
1064 case OP_NOT_WHITESPACE:
1065 set_nottype_bits(start_bits, cbit_space, table_limit, cd);
1066 start_bits[1] |= 0x08;
1067 break;
1068
1069 /* The cbit_space table has vertical tab as whitespace; we have to
1070 avoid setting it. */
1071
1072 case OP_WHITESPACE:
1073 c = start_bits[1]; /* Save in case it was already set */
1074 set_type_bits(start_bits, cbit_space, table_limit, cd);
1075 start_bits[1] = (start_bits[1] & ~0x08) | c;
1076 break;
1077
1078 case OP_NOT_WORDCHAR:
1079 set_nottype_bits(start_bits, cbit_word, table_limit, cd);
1080 break;
1081
1082 case OP_WORDCHAR:
1083 set_type_bits(start_bits, cbit_word, table_limit, cd);
1084 break;
1085 }
1086
1087 tcode += 2;
1088 break;
1089
1090 /* Character class where all the information is in a bit map: set the
1091 bits and either carry on or not, according to the repeat count. If it was
1092 a negative class, and we are operating with UTF-8 characters, any byte
1093 with a value >= 0xc4 is a potentially valid starter because it starts a
1094 character with a value > 255. */
1095
1096 case OP_NCLASS:
1097 #ifdef SUPPORT_UTF8
1098 if (utf8)
1099 {
1100 start_bits[24] |= 0xf0; /* Bits for 0xc4 - 0xc8 */
1101 memset(start_bits+25, 0xff, 7); /* Bits for 0xc9 - 0xff */
1102 }
1103 #endif
1104 /* Fall through */
1105
1106 case OP_CLASS:
1107 {
1108 tcode++;
1109
1110 /* In UTF-8 mode, the bits in a bit map correspond to character
1111 values, not to byte values. However, the bit map we are constructing is
1112 for byte values. So we have to do a conversion for characters whose
1113 value is > 127. In fact, there are only two possible starting bytes for
1114 characters in the range 128 - 255. */
1115
1116 #ifdef SUPPORT_UTF8
1117 if (utf8)
1118 {
1119 for (c = 0; c < 16; c++) start_bits[c] |= tcode[c];
1120 for (c = 128; c < 256; c++)
1121 {
1122 if ((tcode[c/8] && (1 << (c&7))) != 0)
1123 {
1124 int d = (c >> 6) | 0xc0; /* Set bit for this starter */
1125 start_bits[d/8] |= (1 << (d&7)); /* and then skip on to the */
1126 c = (c & 0xc0) + 0x40 - 1; /* next relevant character. */
1127 }
1128 }
1129 }
1130
1131 /* In non-UTF-8 mode, the two bit maps are completely compatible. */
1132
1133 else
1134 #endif
1135 {
1136 for (c = 0; c < 32; c++) start_bits[c] |= tcode[c];
1137 }
1138
1139 /* Advance past the bit map, and act on what follows. For a zero
1140 minimum repeat, continue; otherwise stop processing. */
1141
1142 tcode += 32;
1143 switch (*tcode)
1144 {
1145 case OP_CRSTAR:
1146 case OP_CRMINSTAR:
1147 case OP_CRQUERY:
1148 case OP_CRMINQUERY:
1149 tcode++;
1150 break;
1151
1152 case OP_CRRANGE:
1153 case OP_CRMINRANGE:
1154 if (((tcode[1] << 8) + tcode[2]) == 0) tcode += 5;
1155 else try_next = FALSE;
1156 break;
1157
1158 default:
1159 try_next = FALSE;
1160 break;
1161 }
1162 }
1163 break; /* End of bitmap class handling */
1164
1165 } /* End of switch */
1166 } /* End of try_next loop */
1167
1168 code += GET(code, 1); /* Advance to next branch */
1169 }
1170 while (*code == OP_ALT);
1171 return yield;
1172 }
1173
1174
1175
1176
1177
1178 /*************************************************
1179 * Study a compiled expression *
1180 *************************************************/
1181
1182 /* This function is handed a compiled expression that it must study to produce
1183 information that will speed up the matching. It returns a pcre_extra block
1184 which then gets handed back to pcre_exec().
1185
1186 Arguments:
1187 re points to the compiled expression
1188 options contains option bits
1189 errorptr points to where to place error messages;
1190 set NULL unless error
1191
1192 Returns: pointer to a pcre_extra block, with study_data filled in and the
1193 appropriate flags set;
1194 NULL on error or if no optimization possible
1195 */
1196
1197 PCRE_EXP_DEFN pcre_extra * PCRE_CALL_CONVENTION
1198 pcre_study(const pcre *external_re, int options, const char **errorptr)
1199 {
1200 int min;
1201 BOOL bits_set = FALSE;
1202 uschar start_bits[32];
1203 pcre_extra *extra;
1204 pcre_study_data *study;
1205 const uschar *tables;
1206 uschar *code;
1207 compile_data compile_block;
1208 const real_pcre *re = (const real_pcre *)external_re;
1209
1210 *errorptr = NULL;
1211
1212 if (re == NULL || re->magic_number != MAGIC_NUMBER)
1213 {
1214 *errorptr = "argument is not a compiled regular expression";
1215 return NULL;
1216 }
1217
1218 if ((options & ~PUBLIC_STUDY_OPTIONS) != 0)
1219 {
1220 *errorptr = "unknown or incorrect option bit(s) set";
1221 return NULL;
1222 }
1223
1224 code = (uschar *)re + re->name_table_offset +
1225 (re->name_count * re->name_entry_size);
1226
1227 /* For an anchored pattern, or an unanchored pattern that has a first char, or
1228 a multiline pattern that matches only at "line starts", there is no point in
1229 seeking a list of starting bytes. */
1230
1231 if ((re->options & PCRE_ANCHORED) == 0 &&
1232 (re->flags & (PCRE_FIRSTSET|PCRE_STARTLINE)) == 0)
1233 {
1234 int rc;
1235
1236 /* Set the character tables in the block that is passed around */
1237
1238 tables = re->tables;
1239 if (tables == NULL)
1240 (void)pcre_fullinfo(external_re, NULL, PCRE_INFO_DEFAULT_TABLES,
1241 (void *)(&tables));
1242
1243 compile_block.lcc = tables + lcc_offset;
1244 compile_block.fcc = tables + fcc_offset;
1245 compile_block.cbits = tables + cbits_offset;
1246 compile_block.ctypes = tables + ctypes_offset;
1247
1248 /* See if we can find a fixed set of initial characters for the pattern. */
1249
1250 memset(start_bits, 0, 32 * sizeof(uschar));
1251 rc = set_start_bits(code, start_bits, (re->options & PCRE_UTF8) != 0,
1252 &compile_block);
1253 bits_set = rc == SSB_DONE;
1254 if (rc == SSB_UNKNOWN) *errorptr = "internal error: opcode not recognized";
1255 }
1256
1257 /* Find the minimum length of subject string. */
1258
1259 switch(min = find_minlength(code, code, re->options))
1260 {
1261 case -2: *errorptr = "internal error: missing capturing bracket"; break;
1262 case -3: *errorptr = "internal error: opcode not recognized"; break;
1263 default: break;
1264 }
1265
1266 /* Return NULL if there's been an error or if no optimization is possible. */
1267
1268 if (*errorptr != NULL || (!bits_set && min < 0)) return NULL;
1269
1270 /* Get a pcre_extra block and a pcre_study_data block. The study data is put in
1271 the latter, which is pointed to by the former, which may also get additional
1272 data set later by the calling program. At the moment, the size of
1273 pcre_study_data is fixed. We nevertheless save it in a field for returning via
1274 the pcre_fullinfo() function so that if it becomes variable in the future, we
1275 don't have to change that code. */
1276
1277 extra = (pcre_extra *)(pcre_malloc)
1278 (sizeof(pcre_extra) + sizeof(pcre_study_data));
1279
1280 if (extra == NULL)
1281 {
1282 *errorptr = "failed to get memory";
1283 return NULL;
1284 }
1285
1286 study = (pcre_study_data *)((char *)extra + sizeof(pcre_extra));
1287 extra->flags = PCRE_EXTRA_STUDY_DATA;
1288 extra->study_data = study;
1289
1290 study->size = sizeof(pcre_study_data);
1291 study->flags = 0;
1292
1293 if (bits_set)
1294 {
1295 study->flags |= PCRE_STUDY_MAPPED;
1296 memcpy(study->start_bits, start_bits, sizeof(start_bits));
1297 }
1298
1299 if (min >= 0)
1300 {
1301 study->flags |= PCRE_STUDY_MINLEN;
1302 study->minlength = min;
1303 }
1304
1305 return extra;
1306 }
1307
1308 /* End of pcre_study.c */

Properties

Name Value
svn:eol-style native
svn:keywords "Author Date Id Revision Url"

  ViewVC Help
Powered by ViewVC 1.1.5