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Revision 487 - (show annotations) (download)
Wed Jan 6 10:26:55 2010 UTC (4 years, 10 months ago) by ph10
File MIME type: text/plain
File size: 27444 byte(s)
Tidying updates for 8.01-RC1 release.

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
52 /* Returns from set_start_bits() */
53
54 enum { SSB_FAIL, SSB_DONE, SSB_CONTINUE };
55
56
57
58 /*************************************************
59 * Find the minimum subject length for a group *
60 *************************************************/
61
62 /* Scan a parenthesized group and compute the minimum length of subject that
63 is needed to match it. This is a lower bound; it does not mean there is a
64 string of that length that matches. In UTF8 mode, the result is in characters
65 rather than bytes.
66
67 Arguments:
68 code pointer to start of group (the bracket)
69 startcode pointer to start of the whole pattern
70 options the compiling options
71
72 Returns: the minimum length
73 -1 if \C was encountered
74 -2 internal error (missing capturing bracket)
75 */
76
77 static int
78 find_minlength(const uschar *code, const uschar *startcode, int options)
79 {
80 int length = -1;
81 BOOL utf8 = (options & PCRE_UTF8) != 0;
82 BOOL had_recurse = FALSE;
83 register int branchlength = 0;
84 register uschar *cc = (uschar *)code + 1 + LINK_SIZE;
85
86 if (*code == OP_CBRA || *code == OP_SCBRA) cc += 2;
87
88 /* Scan along the opcodes for this branch. If we get to the end of the
89 branch, check the length against that of the other branches. */
90
91 for (;;)
92 {
93 int d, min;
94 uschar *cs, *ce;
95 register int op = *cc;
96
97 switch (op)
98 {
99 case OP_COND:
100 case OP_SCOND:
101
102 /* If there is only one branch in a condition, the implied branch has zero
103 length, so we don't add anything. This covers the DEFINE "condition"
104 automatically. */
105
106 cs = cc + GET(cc, 1);
107 if (*cs != OP_ALT)
108 {
109 cc = cs + 1 + LINK_SIZE;
110 break;
111 }
112
113 /* Otherwise we can fall through and treat it the same as any other
114 subpattern. */
115
116 case OP_CBRA:
117 case OP_SCBRA:
118 case OP_BRA:
119 case OP_SBRA:
120 case OP_ONCE:
121 d = find_minlength(cc, startcode, options);
122 if (d < 0) return d;
123 branchlength += d;
124 do cc += GET(cc, 1); while (*cc == OP_ALT);
125 cc += 1 + LINK_SIZE;
126 break;
127
128 /* Reached end of a branch; if it's a ket it is the end of a nested
129 call. If it's ALT it is an alternation in a nested call. If it is
130 END it's the end of the outer call. All can be handled by the same code. */
131
132 case OP_ALT:
133 case OP_KET:
134 case OP_KETRMAX:
135 case OP_KETRMIN:
136 case OP_END:
137 if (length < 0 || (!had_recurse && branchlength < length))
138 length = branchlength;
139 if (*cc != OP_ALT) return length;
140 cc += 1 + LINK_SIZE;
141 branchlength = 0;
142 had_recurse = FALSE;
143 break;
144
145 /* Skip over assertive subpatterns */
146
147 case OP_ASSERT:
148 case OP_ASSERT_NOT:
149 case OP_ASSERTBACK:
150 case OP_ASSERTBACK_NOT:
151 do cc += GET(cc, 1); while (*cc == OP_ALT);
152 /* Fall through */
153
154 /* Skip over things that don't match chars */
155
156 case OP_REVERSE:
157 case OP_CREF:
158 case OP_NCREF:
159 case OP_RREF:
160 case OP_NRREF:
161 case OP_DEF:
162 case OP_OPT:
163 case OP_CALLOUT:
164 case OP_SOD:
165 case OP_SOM:
166 case OP_EOD:
167 case OP_EODN:
168 case OP_CIRC:
169 case OP_DOLL:
170 case OP_NOT_WORD_BOUNDARY:
171 case OP_WORD_BOUNDARY:
172 cc += _pcre_OP_lengths[*cc];
173 break;
174
175 /* Skip over a subpattern that has a {0} or {0,x} quantifier */
176
177 case OP_BRAZERO:
178 case OP_BRAMINZERO:
179 case OP_SKIPZERO:
180 cc += _pcre_OP_lengths[*cc];
181 do cc += GET(cc, 1); while (*cc == OP_ALT);
182 cc += 1 + LINK_SIZE;
183 break;
184
185 /* Handle literal characters and + repetitions */
186
187 case OP_CHAR:
188 case OP_CHARNC:
189 case OP_NOT:
190 case OP_PLUS:
191 case OP_MINPLUS:
192 case OP_POSPLUS:
193 case OP_NOTPLUS:
194 case OP_NOTMINPLUS:
195 case OP_NOTPOSPLUS:
196 branchlength++;
197 cc += 2;
198 #ifdef SUPPORT_UTF8
199 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
200 #endif
201 break;
202
203 case OP_TYPEPLUS:
204 case OP_TYPEMINPLUS:
205 case OP_TYPEPOSPLUS:
206 branchlength++;
207 cc += (cc[1] == OP_PROP || cc[1] == OP_NOTPROP)? 4 : 2;
208 break;
209
210 /* Handle exact repetitions. The count is already in characters, but we
211 need to skip over a multibyte character in UTF8 mode. */
212
213 case OP_EXACT:
214 case OP_NOTEXACT:
215 branchlength += GET2(cc,1);
216 cc += 4;
217 #ifdef SUPPORT_UTF8
218 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
219 #endif
220 break;
221
222 case OP_TYPEEXACT:
223 branchlength += GET2(cc,1);
224 cc += (cc[3] == OP_PROP || cc[3] == OP_NOTPROP)? 6 : 4;
225 break;
226
227 /* Handle single-char non-literal matchers */
228
229 case OP_PROP:
230 case OP_NOTPROP:
231 cc += 2;
232 /* Fall through */
233
234 case OP_NOT_DIGIT:
235 case OP_DIGIT:
236 case OP_NOT_WHITESPACE:
237 case OP_WHITESPACE:
238 case OP_NOT_WORDCHAR:
239 case OP_WORDCHAR:
240 case OP_ANY:
241 case OP_ALLANY:
242 case OP_EXTUNI:
243 case OP_HSPACE:
244 case OP_NOT_HSPACE:
245 case OP_VSPACE:
246 case OP_NOT_VSPACE:
247 branchlength++;
248 cc++;
249 break;
250
251 /* "Any newline" might match two characters */
252
253 case OP_ANYNL:
254 branchlength += 2;
255 cc++;
256 break;
257
258 /* The single-byte matcher means we can't proceed in UTF-8 mode */
259
260 case OP_ANYBYTE:
261 #ifdef SUPPORT_UTF8
262 if (utf8) return -1;
263 #endif
264 branchlength++;
265 cc++;
266 break;
267
268 /* For repeated character types, we have to test for \p and \P, which have
269 an extra two bytes of parameters. */
270
271 case OP_TYPESTAR:
272 case OP_TYPEMINSTAR:
273 case OP_TYPEQUERY:
274 case OP_TYPEMINQUERY:
275 case OP_TYPEPOSSTAR:
276 case OP_TYPEPOSQUERY:
277 if (cc[1] == OP_PROP || cc[1] == OP_NOTPROP) cc += 2;
278 cc += _pcre_OP_lengths[op];
279 break;
280
281 case OP_TYPEUPTO:
282 case OP_TYPEMINUPTO:
283 case OP_TYPEPOSUPTO:
284 if (cc[3] == OP_PROP || cc[3] == OP_NOTPROP) cc += 2;
285 cc += _pcre_OP_lengths[op];
286 break;
287
288 /* Check a class for variable quantification */
289
290 #ifdef SUPPORT_UTF8
291 case OP_XCLASS:
292 cc += GET(cc, 1) - 33;
293 /* Fall through */
294 #endif
295
296 case OP_CLASS:
297 case OP_NCLASS:
298 cc += 33;
299
300 switch (*cc)
301 {
302 case OP_CRPLUS:
303 case OP_CRMINPLUS:
304 branchlength++;
305 /* Fall through */
306
307 case OP_CRSTAR:
308 case OP_CRMINSTAR:
309 case OP_CRQUERY:
310 case OP_CRMINQUERY:
311 cc++;
312 break;
313
314 case OP_CRRANGE:
315 case OP_CRMINRANGE:
316 branchlength += GET2(cc,1);
317 cc += 5;
318 break;
319
320 default:
321 branchlength++;
322 break;
323 }
324 break;
325
326 /* Backreferences and subroutine calls are treated in the same way: we find
327 the minimum length for the subpattern. A recursion, however, causes an
328 a flag to be set that causes the length of this branch to be ignored. The
329 logic is that a recursion can only make sense if there is another
330 alternation that stops the recursing. That will provide the minimum length
331 (when no recursion happens). A backreference within the group that it is
332 referencing behaves in the same way.
333
334 If PCRE_JAVASCRIPT_COMPAT is set, a backreference to an unset bracket
335 matches an empty string (by default it causes a matching failure), so in
336 that case we must set the minimum length to zero. */
337
338 case OP_REF:
339 if ((options & PCRE_JAVASCRIPT_COMPAT) == 0)
340 {
341 ce = cs = (uschar *)_pcre_find_bracket(startcode, utf8, GET2(cc, 1));
342 if (cs == NULL) return -2;
343 do ce += GET(ce, 1); while (*ce == OP_ALT);
344 if (cc > cs && cc < ce)
345 {
346 d = 0;
347 had_recurse = TRUE;
348 }
349 else d = find_minlength(cs, startcode, options);
350 }
351 else d = 0;
352 cc += 3;
353
354 /* Handle repeated back references */
355
356 switch (*cc)
357 {
358 case OP_CRSTAR:
359 case OP_CRMINSTAR:
360 case OP_CRQUERY:
361 case OP_CRMINQUERY:
362 min = 0;
363 cc++;
364 break;
365
366 case OP_CRRANGE:
367 case OP_CRMINRANGE:
368 min = GET2(cc, 1);
369 cc += 5;
370 break;
371
372 default:
373 min = 1;
374 break;
375 }
376
377 branchlength += min * d;
378 break;
379
380 case OP_RECURSE:
381 cs = ce = (uschar *)startcode + GET(cc, 1);
382 if (cs == NULL) return -2;
383 do ce += GET(ce, 1); while (*ce == OP_ALT);
384 if (cc > cs && cc < ce)
385 had_recurse = TRUE;
386 else
387 branchlength += find_minlength(cs, startcode, options);
388 cc += 1 + LINK_SIZE;
389 break;
390
391 /* Anything else does not or need not match a character. We can get the
392 item's length from the table, but for those that can match zero occurrences
393 of a character, we must take special action for UTF-8 characters. */
394
395 case OP_UPTO:
396 case OP_NOTUPTO:
397 case OP_MINUPTO:
398 case OP_NOTMINUPTO:
399 case OP_POSUPTO:
400 case OP_STAR:
401 case OP_MINSTAR:
402 case OP_NOTMINSTAR:
403 case OP_POSSTAR:
404 case OP_NOTPOSSTAR:
405 case OP_QUERY:
406 case OP_MINQUERY:
407 case OP_NOTMINQUERY:
408 case OP_POSQUERY:
409 case OP_NOTPOSQUERY:
410 cc += _pcre_OP_lengths[op];
411 #ifdef SUPPORT_UTF8
412 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
413 #endif
414 break;
415
416 /* For the record, these are the opcodes that are matched by "default":
417 OP_ACCEPT, OP_CLOSE, OP_COMMIT, OP_FAIL, OP_PRUNE, OP_SET_SOM, OP_SKIP,
418 OP_THEN. */
419
420 default:
421 cc += _pcre_OP_lengths[op];
422 break;
423 }
424 }
425 /* Control never gets here */
426 }
427
428
429
430 /*************************************************
431 * Set a bit and maybe its alternate case *
432 *************************************************/
433
434 /* Given a character, set its bit in the table, and also the bit for the other
435 version of a letter if we are caseless.
436
437 Arguments:
438 start_bits points to the bit map
439 c is the character
440 caseless the caseless flag
441 cd the block with char table pointers
442
443 Returns: nothing
444 */
445
446 static void
447 set_table_bit(uschar *start_bits, unsigned int c, BOOL caseless,
448 compile_data *cd)
449 {
450 start_bits[c/8] |= (1 << (c&7));
451 if (caseless && (cd->ctypes[c] & ctype_letter) != 0)
452 start_bits[cd->fcc[c]/8] |= (1 << (cd->fcc[c]&7));
453 }
454
455
456
457 /*************************************************
458 * Create bitmap of starting bytes *
459 *************************************************/
460
461 /* This function scans a compiled unanchored expression recursively and
462 attempts to build a bitmap of the set of possible starting bytes. As time goes
463 by, we may be able to get more clever at doing this. The SSB_CONTINUE return is
464 useful for parenthesized groups in patterns such as (a*)b where the group
465 provides some optional starting bytes but scanning must continue at the outer
466 level to find at least one mandatory byte. At the outermost level, this
467 function fails unless the result is SSB_DONE.
468
469 Arguments:
470 code points to an expression
471 start_bits points to a 32-byte table, initialized to 0
472 caseless the current state of the caseless flag
473 utf8 TRUE if in UTF-8 mode
474 cd the block with char table pointers
475
476 Returns: SSB_FAIL => Failed to find any starting bytes
477 SSB_DONE => Found mandatory starting bytes
478 SSB_CONTINUE => Found optional starting bytes
479 */
480
481 static int
482 set_start_bits(const uschar *code, uschar *start_bits, BOOL caseless,
483 BOOL utf8, compile_data *cd)
484 {
485 register int c;
486 int yield = SSB_DONE;
487
488 #if 0
489 /* ========================================================================= */
490 /* The following comment and code was inserted in January 1999. In May 2006,
491 when it was observed to cause compiler warnings about unused values, I took it
492 out again. If anybody is still using OS/2, they will have to put it back
493 manually. */
494
495 /* This next statement and the later reference to dummy are here in order to
496 trick the optimizer of the IBM C compiler for OS/2 into generating correct
497 code. Apparently IBM isn't going to fix the problem, and we would rather not
498 disable optimization (in this module it actually makes a big difference, and
499 the pcre module can use all the optimization it can get). */
500
501 volatile int dummy;
502 /* ========================================================================= */
503 #endif
504
505 do
506 {
507 const uschar *tcode = code + (((int)*code == OP_CBRA)? 3:1) + LINK_SIZE;
508 BOOL try_next = TRUE;
509
510 while (try_next) /* Loop for items in this branch */
511 {
512 int rc;
513 switch(*tcode)
514 {
515 /* Fail if we reach something we don't understand */
516
517 default:
518 return SSB_FAIL;
519
520 /* If we hit a bracket or a positive lookahead assertion, recurse to set
521 bits from within the subpattern. If it can't find anything, we have to
522 give up. If it finds some mandatory character(s), we are done for this
523 branch. Otherwise, carry on scanning after the subpattern. */
524
525 case OP_BRA:
526 case OP_SBRA:
527 case OP_CBRA:
528 case OP_SCBRA:
529 case OP_ONCE:
530 case OP_ASSERT:
531 rc = set_start_bits(tcode, start_bits, caseless, utf8, cd);
532 if (rc == SSB_FAIL) return SSB_FAIL;
533 if (rc == SSB_DONE) try_next = FALSE; else
534 {
535 do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
536 tcode += 1 + LINK_SIZE;
537 }
538 break;
539
540 /* If we hit ALT or KET, it means we haven't found anything mandatory in
541 this branch, though we might have found something optional. For ALT, we
542 continue with the next alternative, but we have to arrange that the final
543 result from subpattern is SSB_CONTINUE rather than SSB_DONE. For KET,
544 return SSB_CONTINUE: if this is the top level, that indicates failure,
545 but after a nested subpattern, it causes scanning to continue. */
546
547 case OP_ALT:
548 yield = SSB_CONTINUE;
549 try_next = FALSE;
550 break;
551
552 case OP_KET:
553 case OP_KETRMAX:
554 case OP_KETRMIN:
555 return SSB_CONTINUE;
556
557 /* Skip over callout */
558
559 case OP_CALLOUT:
560 tcode += 2 + 2*LINK_SIZE;
561 break;
562
563 /* Skip over lookbehind and negative lookahead assertions */
564
565 case OP_ASSERT_NOT:
566 case OP_ASSERTBACK:
567 case OP_ASSERTBACK_NOT:
568 do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
569 tcode += 1 + LINK_SIZE;
570 break;
571
572 /* Skip over an option setting, changing the caseless flag */
573
574 case OP_OPT:
575 caseless = (tcode[1] & PCRE_CASELESS) != 0;
576 tcode += 2;
577 break;
578
579 /* BRAZERO does the bracket, but carries on. */
580
581 case OP_BRAZERO:
582 case OP_BRAMINZERO:
583 if (set_start_bits(++tcode, start_bits, caseless, utf8, cd) == SSB_FAIL)
584 return SSB_FAIL;
585 /* =========================================================================
586 See the comment at the head of this function concerning the next line,
587 which was an old fudge for the benefit of OS/2.
588 dummy = 1;
589 ========================================================================= */
590 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
591 tcode += 1 + LINK_SIZE;
592 break;
593
594 /* SKIPZERO skips the bracket. */
595
596 case OP_SKIPZERO:
597 tcode++;
598 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
599 tcode += 1 + LINK_SIZE;
600 break;
601
602 /* Single-char * or ? sets the bit and tries the next item */
603
604 case OP_STAR:
605 case OP_MINSTAR:
606 case OP_POSSTAR:
607 case OP_QUERY:
608 case OP_MINQUERY:
609 case OP_POSQUERY:
610 set_table_bit(start_bits, tcode[1], caseless, cd);
611 tcode += 2;
612 #ifdef SUPPORT_UTF8
613 if (utf8 && tcode[-1] >= 0xc0)
614 tcode += _pcre_utf8_table4[tcode[-1] & 0x3f];
615 #endif
616 break;
617
618 /* Single-char upto sets the bit and tries the next */
619
620 case OP_UPTO:
621 case OP_MINUPTO:
622 case OP_POSUPTO:
623 set_table_bit(start_bits, tcode[3], caseless, cd);
624 tcode += 4;
625 #ifdef SUPPORT_UTF8
626 if (utf8 && tcode[-1] >= 0xc0)
627 tcode += _pcre_utf8_table4[tcode[-1] & 0x3f];
628 #endif
629 break;
630
631 /* At least one single char sets the bit and stops */
632
633 case OP_EXACT: /* Fall through */
634 tcode += 2;
635
636 case OP_CHAR:
637 case OP_CHARNC:
638 case OP_PLUS:
639 case OP_MINPLUS:
640 case OP_POSPLUS:
641 set_table_bit(start_bits, tcode[1], caseless, cd);
642 try_next = FALSE;
643 break;
644
645 /* Single character type sets the bits and stops */
646
647 case OP_NOT_DIGIT:
648 for (c = 0; c < 32; c++)
649 start_bits[c] |= ~cd->cbits[c+cbit_digit];
650 try_next = FALSE;
651 break;
652
653 case OP_DIGIT:
654 for (c = 0; c < 32; c++)
655 start_bits[c] |= cd->cbits[c+cbit_digit];
656 try_next = FALSE;
657 break;
658
659 /* The cbit_space table has vertical tab as whitespace; we have to
660 discard it. */
661
662 case OP_NOT_WHITESPACE:
663 for (c = 0; c < 32; c++)
664 {
665 int d = cd->cbits[c+cbit_space];
666 if (c == 1) d &= ~0x08;
667 start_bits[c] |= ~d;
668 }
669 try_next = FALSE;
670 break;
671
672 /* The cbit_space table has vertical tab as whitespace; we have to
673 discard it. */
674
675 case OP_WHITESPACE:
676 for (c = 0; c < 32; c++)
677 {
678 int d = cd->cbits[c+cbit_space];
679 if (c == 1) d &= ~0x08;
680 start_bits[c] |= d;
681 }
682 try_next = FALSE;
683 break;
684
685 case OP_NOT_WORDCHAR:
686 for (c = 0; c < 32; c++)
687 start_bits[c] |= ~cd->cbits[c+cbit_word];
688 try_next = FALSE;
689 break;
690
691 case OP_WORDCHAR:
692 for (c = 0; c < 32; c++)
693 start_bits[c] |= cd->cbits[c+cbit_word];
694 try_next = FALSE;
695 break;
696
697 /* One or more character type fudges the pointer and restarts, knowing
698 it will hit a single character type and stop there. */
699
700 case OP_TYPEPLUS:
701 case OP_TYPEMINPLUS:
702 tcode++;
703 break;
704
705 case OP_TYPEEXACT:
706 tcode += 3;
707 break;
708
709 /* Zero or more repeats of character types set the bits and then
710 try again. */
711
712 case OP_TYPEUPTO:
713 case OP_TYPEMINUPTO:
714 case OP_TYPEPOSUPTO:
715 tcode += 2; /* Fall through */
716
717 case OP_TYPESTAR:
718 case OP_TYPEMINSTAR:
719 case OP_TYPEPOSSTAR:
720 case OP_TYPEQUERY:
721 case OP_TYPEMINQUERY:
722 case OP_TYPEPOSQUERY:
723 switch(tcode[1])
724 {
725 case OP_ANY:
726 case OP_ALLANY:
727 return SSB_FAIL;
728
729 case OP_NOT_DIGIT:
730 for (c = 0; c < 32; c++)
731 start_bits[c] |= ~cd->cbits[c+cbit_digit];
732 break;
733
734 case OP_DIGIT:
735 for (c = 0; c < 32; c++)
736 start_bits[c] |= cd->cbits[c+cbit_digit];
737 break;
738
739 /* The cbit_space table has vertical tab as whitespace; we have to
740 discard it. */
741
742 case OP_NOT_WHITESPACE:
743 for (c = 0; c < 32; c++)
744 {
745 int d = cd->cbits[c+cbit_space];
746 if (c == 1) d &= ~0x08;
747 start_bits[c] |= ~d;
748 }
749 break;
750
751 /* The cbit_space table has vertical tab as whitespace; we have to
752 discard it. */
753
754 case OP_WHITESPACE:
755 for (c = 0; c < 32; c++)
756 {
757 int d = cd->cbits[c+cbit_space];
758 if (c == 1) d &= ~0x08;
759 start_bits[c] |= d;
760 }
761 break;
762
763 case OP_NOT_WORDCHAR:
764 for (c = 0; c < 32; c++)
765 start_bits[c] |= ~cd->cbits[c+cbit_word];
766 break;
767
768 case OP_WORDCHAR:
769 for (c = 0; c < 32; c++)
770 start_bits[c] |= cd->cbits[c+cbit_word];
771 break;
772 }
773
774 tcode += 2;
775 break;
776
777 /* Character class where all the information is in a bit map: set the
778 bits and either carry on or not, according to the repeat count. If it was
779 a negative class, and we are operating with UTF-8 characters, any byte
780 with a value >= 0xc4 is a potentially valid starter because it starts a
781 character with a value > 255. */
782
783 case OP_NCLASS:
784 #ifdef SUPPORT_UTF8
785 if (utf8)
786 {
787 start_bits[24] |= 0xf0; /* Bits for 0xc4 - 0xc8 */
788 memset(start_bits+25, 0xff, 7); /* Bits for 0xc9 - 0xff */
789 }
790 #endif
791 /* Fall through */
792
793 case OP_CLASS:
794 {
795 tcode++;
796
797 /* In UTF-8 mode, the bits in a bit map correspond to character
798 values, not to byte values. However, the bit map we are constructing is
799 for byte values. So we have to do a conversion for characters whose
800 value is > 127. In fact, there are only two possible starting bytes for
801 characters in the range 128 - 255. */
802
803 #ifdef SUPPORT_UTF8
804 if (utf8)
805 {
806 for (c = 0; c < 16; c++) start_bits[c] |= tcode[c];
807 for (c = 128; c < 256; c++)
808 {
809 if ((tcode[c/8] && (1 << (c&7))) != 0)
810 {
811 int d = (c >> 6) | 0xc0; /* Set bit for this starter */
812 start_bits[d/8] |= (1 << (d&7)); /* and then skip on to the */
813 c = (c & 0xc0) + 0x40 - 1; /* next relevant character. */
814 }
815 }
816 }
817
818 /* In non-UTF-8 mode, the two bit maps are completely compatible. */
819
820 else
821 #endif
822 {
823 for (c = 0; c < 32; c++) start_bits[c] |= tcode[c];
824 }
825
826 /* Advance past the bit map, and act on what follows */
827
828 tcode += 32;
829 switch (*tcode)
830 {
831 case OP_CRSTAR:
832 case OP_CRMINSTAR:
833 case OP_CRQUERY:
834 case OP_CRMINQUERY:
835 tcode++;
836 break;
837
838 case OP_CRRANGE:
839 case OP_CRMINRANGE:
840 if (((tcode[1] << 8) + tcode[2]) == 0) tcode += 5;
841 else try_next = FALSE;
842 break;
843
844 default:
845 try_next = FALSE;
846 break;
847 }
848 }
849 break; /* End of bitmap class handling */
850
851 } /* End of switch */
852 } /* End of try_next loop */
853
854 code += GET(code, 1); /* Advance to next branch */
855 }
856 while (*code == OP_ALT);
857 return yield;
858 }
859
860
861
862 /*************************************************
863 * Study a compiled expression *
864 *************************************************/
865
866 /* This function is handed a compiled expression that it must study to produce
867 information that will speed up the matching. It returns a pcre_extra block
868 which then gets handed back to pcre_exec().
869
870 Arguments:
871 re points to the compiled expression
872 options contains option bits
873 errorptr points to where to place error messages;
874 set NULL unless error
875
876 Returns: pointer to a pcre_extra block, with study_data filled in and the
877 appropriate flags set;
878 NULL on error or if no optimization possible
879 */
880
881 PCRE_EXP_DEFN pcre_extra * PCRE_CALL_CONVENTION
882 pcre_study(const pcre *external_re, int options, const char **errorptr)
883 {
884 int min;
885 BOOL bits_set = FALSE;
886 uschar start_bits[32];
887 pcre_extra *extra;
888 pcre_study_data *study;
889 const uschar *tables;
890 uschar *code;
891 compile_data compile_block;
892 const real_pcre *re = (const real_pcre *)external_re;
893
894 *errorptr = NULL;
895
896 if (re == NULL || re->magic_number != MAGIC_NUMBER)
897 {
898 *errorptr = "argument is not a compiled regular expression";
899 return NULL;
900 }
901
902 if ((options & ~PUBLIC_STUDY_OPTIONS) != 0)
903 {
904 *errorptr = "unknown or incorrect option bit(s) set";
905 return NULL;
906 }
907
908 code = (uschar *)re + re->name_table_offset +
909 (re->name_count * re->name_entry_size);
910
911 /* For an anchored pattern, or an unanchored pattern that has a first char, or
912 a multiline pattern that matches only at "line starts", there is no point in
913 seeking a list of starting bytes. */
914
915 if ((re->options & PCRE_ANCHORED) == 0 &&
916 (re->flags & (PCRE_FIRSTSET|PCRE_STARTLINE)) == 0)
917 {
918 /* Set the character tables in the block that is passed around */
919
920 tables = re->tables;
921 if (tables == NULL)
922 (void)pcre_fullinfo(external_re, NULL, PCRE_INFO_DEFAULT_TABLES,
923 (void *)(&tables));
924
925 compile_block.lcc = tables + lcc_offset;
926 compile_block.fcc = tables + fcc_offset;
927 compile_block.cbits = tables + cbits_offset;
928 compile_block.ctypes = tables + ctypes_offset;
929
930 /* See if we can find a fixed set of initial characters for the pattern. */
931
932 memset(start_bits, 0, 32 * sizeof(uschar));
933 bits_set = set_start_bits(code, start_bits,
934 (re->options & PCRE_CASELESS) != 0, (re->options & PCRE_UTF8) != 0,
935 &compile_block) == SSB_DONE;
936 }
937
938 /* Find the minimum length of subject string. */
939
940 min = find_minlength(code, code, re->options);
941
942 /* Return NULL if no optimization is possible. */
943
944 if (!bits_set && min < 0) return NULL;
945
946 /* Get a pcre_extra block and a pcre_study_data block. The study data is put in
947 the latter, which is pointed to by the former, which may also get additional
948 data set later by the calling program. At the moment, the size of
949 pcre_study_data is fixed. We nevertheless save it in a field for returning via
950 the pcre_fullinfo() function so that if it becomes variable in the future, we
951 don't have to change that code. */
952
953 extra = (pcre_extra *)(pcre_malloc)
954 (sizeof(pcre_extra) + sizeof(pcre_study_data));
955
956 if (extra == NULL)
957 {
958 *errorptr = "failed to get memory";
959 return NULL;
960 }
961
962 study = (pcre_study_data *)((char *)extra + sizeof(pcre_extra));
963 extra->flags = PCRE_EXTRA_STUDY_DATA;
964 extra->study_data = study;
965
966 study->size = sizeof(pcre_study_data);
967 study->flags = 0;
968
969 if (bits_set)
970 {
971 study->flags |= PCRE_STUDY_MAPPED;
972 memcpy(study->start_bits, start_bits, sizeof(start_bits));
973 }
974
975 if (min >= 0)
976 {
977 study->flags |= PCRE_STUDY_MINLEN;
978 study->minlength = min;
979 }
980
981 return extra;
982 }
983
984 /* End of pcre_study.c */

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