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

Contents of /code/trunk/pcre_study.c

Parent Directory Parent Directory | Revision Log Revision Log


Revision 469 - (show annotations) (download)
Mon Oct 19 14:38:48 2009 UTC (5 years, 2 months ago) by ph10
File MIME type: text/plain
File size: 27040 byte(s)
Final doc and source tidies for 8.00

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) 1997-2009 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_CBRA:
100 case OP_SCBRA:
101 case OP_BRA:
102 case OP_SBRA:
103 case OP_ONCE:
104 case OP_COND:
105 case OP_SCOND:
106 d = find_minlength(cc, startcode, options);
107 if (d < 0) return d;
108 branchlength += d;
109 do cc += GET(cc, 1); while (*cc == OP_ALT);
110 cc += 1 + LINK_SIZE;
111 break;
112
113 /* Reached end of a branch; if it's a ket it is the end of a nested
114 call. If it's ALT it is an alternation in a nested call. If it is
115 END it's the end of the outer call. All can be handled by the same code. */
116
117 case OP_ALT:
118 case OP_KET:
119 case OP_KETRMAX:
120 case OP_KETRMIN:
121 case OP_END:
122 if (length < 0 || (!had_recurse && branchlength < length))
123 length = branchlength;
124 if (*cc != OP_ALT) return length;
125 cc += 1 + LINK_SIZE;
126 branchlength = 0;
127 had_recurse = FALSE;
128 break;
129
130 /* Skip over assertive subpatterns */
131
132 case OP_ASSERT:
133 case OP_ASSERT_NOT:
134 case OP_ASSERTBACK:
135 case OP_ASSERTBACK_NOT:
136 do cc += GET(cc, 1); while (*cc == OP_ALT);
137 /* Fall through */
138
139 /* Skip over things that don't match chars */
140
141 case OP_REVERSE:
142 case OP_CREF:
143 case OP_NCREF:
144 case OP_RREF:
145 case OP_NRREF:
146 case OP_DEF:
147 case OP_OPT:
148 case OP_CALLOUT:
149 case OP_SOD:
150 case OP_SOM:
151 case OP_EOD:
152 case OP_EODN:
153 case OP_CIRC:
154 case OP_DOLL:
155 case OP_NOT_WORD_BOUNDARY:
156 case OP_WORD_BOUNDARY:
157 cc += _pcre_OP_lengths[*cc];
158 break;
159
160 /* Skip over a subpattern that has a {0} or {0,x} quantifier */
161
162 case OP_BRAZERO:
163 case OP_BRAMINZERO:
164 case OP_SKIPZERO:
165 cc += _pcre_OP_lengths[*cc];
166 do cc += GET(cc, 1); while (*cc == OP_ALT);
167 cc += 1 + LINK_SIZE;
168 break;
169
170 /* Handle literal characters and + repetitions */
171
172 case OP_CHAR:
173 case OP_CHARNC:
174 case OP_NOT:
175 case OP_PLUS:
176 case OP_MINPLUS:
177 case OP_POSPLUS:
178 case OP_NOTPLUS:
179 case OP_NOTMINPLUS:
180 case OP_NOTPOSPLUS:
181 branchlength++;
182 cc += 2;
183 #ifdef SUPPORT_UTF8
184 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
185 #endif
186 break;
187
188 case OP_TYPEPLUS:
189 case OP_TYPEMINPLUS:
190 case OP_TYPEPOSPLUS:
191 branchlength++;
192 cc += (cc[1] == OP_PROP || cc[1] == OP_NOTPROP)? 4 : 2;
193 break;
194
195 /* Handle exact repetitions. The count is already in characters, but we
196 need to skip over a multibyte character in UTF8 mode. */
197
198 case OP_EXACT:
199 case OP_NOTEXACT:
200 branchlength += GET2(cc,1);
201 cc += 4;
202 #ifdef SUPPORT_UTF8
203 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
204 #endif
205 break;
206
207 case OP_TYPEEXACT:
208 branchlength += GET2(cc,1);
209 cc += (cc[3] == OP_PROP || cc[3] == OP_NOTPROP)? 6 : 4;
210 break;
211
212 /* Handle single-char non-literal matchers */
213
214 case OP_PROP:
215 case OP_NOTPROP:
216 cc += 2;
217 /* Fall through */
218
219 case OP_NOT_DIGIT:
220 case OP_DIGIT:
221 case OP_NOT_WHITESPACE:
222 case OP_WHITESPACE:
223 case OP_NOT_WORDCHAR:
224 case OP_WORDCHAR:
225 case OP_ANY:
226 case OP_ALLANY:
227 case OP_EXTUNI:
228 case OP_HSPACE:
229 case OP_NOT_HSPACE:
230 case OP_VSPACE:
231 case OP_NOT_VSPACE:
232 branchlength++;
233 cc++;
234 break;
235
236 /* "Any newline" might match two characters */
237
238 case OP_ANYNL:
239 branchlength += 2;
240 cc++;
241 break;
242
243 /* The single-byte matcher means we can't proceed in UTF-8 mode */
244
245 case OP_ANYBYTE:
246 #ifdef SUPPORT_UTF8
247 if (utf8) return -1;
248 #endif
249 branchlength++;
250 cc++;
251 break;
252
253 /* For repeated character types, we have to test for \p and \P, which have
254 an extra two bytes of parameters. */
255
256 case OP_TYPESTAR:
257 case OP_TYPEMINSTAR:
258 case OP_TYPEQUERY:
259 case OP_TYPEMINQUERY:
260 case OP_TYPEPOSSTAR:
261 case OP_TYPEPOSQUERY:
262 if (cc[1] == OP_PROP || cc[1] == OP_NOTPROP) cc += 2;
263 cc += _pcre_OP_lengths[op];
264 break;
265
266 case OP_TYPEUPTO:
267 case OP_TYPEMINUPTO:
268 case OP_TYPEPOSUPTO:
269 if (cc[3] == OP_PROP || cc[3] == OP_NOTPROP) cc += 2;
270 cc += _pcre_OP_lengths[op];
271 break;
272
273 /* Check a class for variable quantification */
274
275 #ifdef SUPPORT_UTF8
276 case OP_XCLASS:
277 cc += GET(cc, 1) - 33;
278 /* Fall through */
279 #endif
280
281 case OP_CLASS:
282 case OP_NCLASS:
283 cc += 33;
284
285 switch (*cc)
286 {
287 case OP_CRPLUS:
288 case OP_CRMINPLUS:
289 branchlength++;
290 /* Fall through */
291
292 case OP_CRSTAR:
293 case OP_CRMINSTAR:
294 case OP_CRQUERY:
295 case OP_CRMINQUERY:
296 cc++;
297 break;
298
299 case OP_CRRANGE:
300 case OP_CRMINRANGE:
301 branchlength += GET2(cc,1);
302 cc += 5;
303 break;
304
305 default:
306 branchlength++;
307 break;
308 }
309 break;
310
311 /* Backreferences and subroutine calls are treated in the same way: we find
312 the minimum length for the subpattern. A recursion, however, causes an
313 a flag to be set that causes the length of this branch to be ignored. The
314 logic is that a recursion can only make sense if there is another
315 alternation that stops the recursing. That will provide the minimum length
316 (when no recursion happens). A backreference within the group that it is
317 referencing behaves in the same way.
318
319 If PCRE_JAVASCRIPT_COMPAT is set, a backreference to an unset bracket
320 matches an empty string (by default it causes a matching failure), so in
321 that case we must set the minimum length to zero. */
322
323 case OP_REF:
324 if ((options & PCRE_JAVASCRIPT_COMPAT) == 0)
325 {
326 ce = cs = (uschar *)_pcre_find_bracket(startcode, utf8, GET2(cc, 1));
327 if (cs == NULL) return -2;
328 do ce += GET(ce, 1); while (*ce == OP_ALT);
329 if (cc > cs && cc < ce)
330 {
331 d = 0;
332 had_recurse = TRUE;
333 }
334 else d = find_minlength(cs, startcode, options);
335 }
336 else d = 0;
337 cc += 3;
338
339 /* Handle repeated back references */
340
341 switch (*cc)
342 {
343 case OP_CRSTAR:
344 case OP_CRMINSTAR:
345 case OP_CRQUERY:
346 case OP_CRMINQUERY:
347 min = 0;
348 cc++;
349 break;
350
351 case OP_CRRANGE:
352 case OP_CRMINRANGE:
353 min = GET2(cc, 1);
354 cc += 5;
355 break;
356
357 default:
358 min = 1;
359 break;
360 }
361
362 branchlength += min * d;
363 break;
364
365 case OP_RECURSE:
366 cs = ce = (uschar *)startcode + GET(cc, 1);
367 if (cs == NULL) return -2;
368 do ce += GET(ce, 1); while (*ce == OP_ALT);
369 if (cc > cs && cc < ce)
370 had_recurse = TRUE;
371 else
372 branchlength += find_minlength(cs, startcode, options);
373 cc += 1 + LINK_SIZE;
374 break;
375
376 /* Anything else does not or need not match a character. We can get the
377 item's length from the table, but for those that can match zero occurrences
378 of a character, we must take special action for UTF-8 characters. */
379
380 case OP_UPTO:
381 case OP_NOTUPTO:
382 case OP_MINUPTO:
383 case OP_NOTMINUPTO:
384 case OP_POSUPTO:
385 case OP_STAR:
386 case OP_MINSTAR:
387 case OP_NOTMINSTAR:
388 case OP_POSSTAR:
389 case OP_NOTPOSSTAR:
390 case OP_QUERY:
391 case OP_MINQUERY:
392 case OP_NOTMINQUERY:
393 case OP_POSQUERY:
394 case OP_NOTPOSQUERY:
395 cc += _pcre_OP_lengths[op];
396 #ifdef SUPPORT_UTF8
397 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
398 #endif
399 break;
400
401 /* For the record, these are the opcodes that are matched by "default":
402 OP_ACCEPT, OP_CLOSE, OP_COMMIT, OP_FAIL, OP_PRUNE, OP_SET_SOM, OP_SKIP,
403 OP_THEN. */
404
405 default:
406 cc += _pcre_OP_lengths[op];
407 break;
408 }
409 }
410 /* Control never gets here */
411 }
412
413
414
415 /*************************************************
416 * Set a bit and maybe its alternate case *
417 *************************************************/
418
419 /* Given a character, set its bit in the table, and also the bit for the other
420 version of a letter if we are caseless.
421
422 Arguments:
423 start_bits points to the bit map
424 c is the character
425 caseless the caseless flag
426 cd the block with char table pointers
427
428 Returns: nothing
429 */
430
431 static void
432 set_bit(uschar *start_bits, unsigned int c, BOOL caseless, compile_data *cd)
433 {
434 start_bits[c/8] |= (1 << (c&7));
435 if (caseless && (cd->ctypes[c] & ctype_letter) != 0)
436 start_bits[cd->fcc[c]/8] |= (1 << (cd->fcc[c]&7));
437 }
438
439
440
441 /*************************************************
442 * Create bitmap of starting bytes *
443 *************************************************/
444
445 /* This function scans a compiled unanchored expression recursively and
446 attempts to build a bitmap of the set of possible starting bytes. As time goes
447 by, we may be able to get more clever at doing this. The SSB_CONTINUE return is
448 useful for parenthesized groups in patterns such as (a*)b where the group
449 provides some optional starting bytes but scanning must continue at the outer
450 level to find at least one mandatory byte. At the outermost level, this
451 function fails unless the result is SSB_DONE.
452
453 Arguments:
454 code points to an expression
455 start_bits points to a 32-byte table, initialized to 0
456 caseless the current state of the caseless flag
457 utf8 TRUE if in UTF-8 mode
458 cd the block with char table pointers
459
460 Returns: SSB_FAIL => Failed to find any starting bytes
461 SSB_DONE => Found mandatory starting bytes
462 SSB_CONTINUE => Found optional starting bytes
463 */
464
465 static int
466 set_start_bits(const uschar *code, uschar *start_bits, BOOL caseless,
467 BOOL utf8, compile_data *cd)
468 {
469 register int c;
470 int yield = SSB_DONE;
471
472 #if 0
473 /* ========================================================================= */
474 /* The following comment and code was inserted in January 1999. In May 2006,
475 when it was observed to cause compiler warnings about unused values, I took it
476 out again. If anybody is still using OS/2, they will have to put it back
477 manually. */
478
479 /* This next statement and the later reference to dummy are here in order to
480 trick the optimizer of the IBM C compiler for OS/2 into generating correct
481 code. Apparently IBM isn't going to fix the problem, and we would rather not
482 disable optimization (in this module it actually makes a big difference, and
483 the pcre module can use all the optimization it can get). */
484
485 volatile int dummy;
486 /* ========================================================================= */
487 #endif
488
489 do
490 {
491 const uschar *tcode = code + (((int)*code == OP_CBRA)? 3:1) + LINK_SIZE;
492 BOOL try_next = TRUE;
493
494 while (try_next) /* Loop for items in this branch */
495 {
496 int rc;
497 switch(*tcode)
498 {
499 /* Fail if we reach something we don't understand */
500
501 default:
502 return SSB_FAIL;
503
504 /* If we hit a bracket or a positive lookahead assertion, recurse to set
505 bits from within the subpattern. If it can't find anything, we have to
506 give up. If it finds some mandatory character(s), we are done for this
507 branch. Otherwise, carry on scanning after the subpattern. */
508
509 case OP_BRA:
510 case OP_SBRA:
511 case OP_CBRA:
512 case OP_SCBRA:
513 case OP_ONCE:
514 case OP_ASSERT:
515 rc = set_start_bits(tcode, start_bits, caseless, utf8, cd);
516 if (rc == SSB_FAIL) return SSB_FAIL;
517 if (rc == SSB_DONE) try_next = FALSE; else
518 {
519 do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
520 tcode += 1 + LINK_SIZE;
521 }
522 break;
523
524 /* If we hit ALT or KET, it means we haven't found anything mandatory in
525 this branch, though we might have found something optional. For ALT, we
526 continue with the next alternative, but we have to arrange that the final
527 result from subpattern is SSB_CONTINUE rather than SSB_DONE. For KET,
528 return SSB_CONTINUE: if this is the top level, that indicates failure,
529 but after a nested subpattern, it causes scanning to continue. */
530
531 case OP_ALT:
532 yield = SSB_CONTINUE;
533 try_next = FALSE;
534 break;
535
536 case OP_KET:
537 case OP_KETRMAX:
538 case OP_KETRMIN:
539 return SSB_CONTINUE;
540
541 /* Skip over callout */
542
543 case OP_CALLOUT:
544 tcode += 2 + 2*LINK_SIZE;
545 break;
546
547 /* Skip over lookbehind and negative lookahead assertions */
548
549 case OP_ASSERT_NOT:
550 case OP_ASSERTBACK:
551 case OP_ASSERTBACK_NOT:
552 do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
553 tcode += 1 + LINK_SIZE;
554 break;
555
556 /* Skip over an option setting, changing the caseless flag */
557
558 case OP_OPT:
559 caseless = (tcode[1] & PCRE_CASELESS) != 0;
560 tcode += 2;
561 break;
562
563 /* BRAZERO does the bracket, but carries on. */
564
565 case OP_BRAZERO:
566 case OP_BRAMINZERO:
567 if (set_start_bits(++tcode, start_bits, caseless, utf8, cd) == SSB_FAIL)
568 return SSB_FAIL;
569 /* =========================================================================
570 See the comment at the head of this function concerning the next line,
571 which was an old fudge for the benefit of OS/2.
572 dummy = 1;
573 ========================================================================= */
574 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
575 tcode += 1 + LINK_SIZE;
576 break;
577
578 /* SKIPZERO skips the bracket. */
579
580 case OP_SKIPZERO:
581 tcode++;
582 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
583 tcode += 1 + LINK_SIZE;
584 break;
585
586 /* Single-char * or ? sets the bit and tries the next item */
587
588 case OP_STAR:
589 case OP_MINSTAR:
590 case OP_POSSTAR:
591 case OP_QUERY:
592 case OP_MINQUERY:
593 case OP_POSQUERY:
594 set_bit(start_bits, tcode[1], caseless, cd);
595 tcode += 2;
596 #ifdef SUPPORT_UTF8
597 if (utf8 && tcode[-1] >= 0xc0)
598 tcode += _pcre_utf8_table4[tcode[-1] & 0x3f];
599 #endif
600 break;
601
602 /* Single-char upto sets the bit and tries the next */
603
604 case OP_UPTO:
605 case OP_MINUPTO:
606 case OP_POSUPTO:
607 set_bit(start_bits, tcode[3], caseless, cd);
608 tcode += 4;
609 #ifdef SUPPORT_UTF8
610 if (utf8 && tcode[-1] >= 0xc0)
611 tcode += _pcre_utf8_table4[tcode[-1] & 0x3f];
612 #endif
613 break;
614
615 /* At least one single char sets the bit and stops */
616
617 case OP_EXACT: /* Fall through */
618 tcode += 2;
619
620 case OP_CHAR:
621 case OP_CHARNC:
622 case OP_PLUS:
623 case OP_MINPLUS:
624 case OP_POSPLUS:
625 set_bit(start_bits, tcode[1], caseless, cd);
626 try_next = FALSE;
627 break;
628
629 /* Single character type sets the bits and stops */
630
631 case OP_NOT_DIGIT:
632 for (c = 0; c < 32; c++)
633 start_bits[c] |= ~cd->cbits[c+cbit_digit];
634 try_next = FALSE;
635 break;
636
637 case OP_DIGIT:
638 for (c = 0; c < 32; c++)
639 start_bits[c] |= cd->cbits[c+cbit_digit];
640 try_next = FALSE;
641 break;
642
643 /* The cbit_space table has vertical tab as whitespace; we have to
644 discard it. */
645
646 case OP_NOT_WHITESPACE:
647 for (c = 0; c < 32; c++)
648 {
649 int d = cd->cbits[c+cbit_space];
650 if (c == 1) d &= ~0x08;
651 start_bits[c] |= ~d;
652 }
653 try_next = FALSE;
654 break;
655
656 /* The cbit_space table has vertical tab as whitespace; we have to
657 discard it. */
658
659 case OP_WHITESPACE:
660 for (c = 0; c < 32; c++)
661 {
662 int d = cd->cbits[c+cbit_space];
663 if (c == 1) d &= ~0x08;
664 start_bits[c] |= d;
665 }
666 try_next = FALSE;
667 break;
668
669 case OP_NOT_WORDCHAR:
670 for (c = 0; c < 32; c++)
671 start_bits[c] |= ~cd->cbits[c+cbit_word];
672 try_next = FALSE;
673 break;
674
675 case OP_WORDCHAR:
676 for (c = 0; c < 32; c++)
677 start_bits[c] |= cd->cbits[c+cbit_word];
678 try_next = FALSE;
679 break;
680
681 /* One or more character type fudges the pointer and restarts, knowing
682 it will hit a single character type and stop there. */
683
684 case OP_TYPEPLUS:
685 case OP_TYPEMINPLUS:
686 tcode++;
687 break;
688
689 case OP_TYPEEXACT:
690 tcode += 3;
691 break;
692
693 /* Zero or more repeats of character types set the bits and then
694 try again. */
695
696 case OP_TYPEUPTO:
697 case OP_TYPEMINUPTO:
698 case OP_TYPEPOSUPTO:
699 tcode += 2; /* Fall through */
700
701 case OP_TYPESTAR:
702 case OP_TYPEMINSTAR:
703 case OP_TYPEPOSSTAR:
704 case OP_TYPEQUERY:
705 case OP_TYPEMINQUERY:
706 case OP_TYPEPOSQUERY:
707 switch(tcode[1])
708 {
709 case OP_ANY:
710 case OP_ALLANY:
711 return SSB_FAIL;
712
713 case OP_NOT_DIGIT:
714 for (c = 0; c < 32; c++)
715 start_bits[c] |= ~cd->cbits[c+cbit_digit];
716 break;
717
718 case OP_DIGIT:
719 for (c = 0; c < 32; c++)
720 start_bits[c] |= cd->cbits[c+cbit_digit];
721 break;
722
723 /* The cbit_space table has vertical tab as whitespace; we have to
724 discard it. */
725
726 case OP_NOT_WHITESPACE:
727 for (c = 0; c < 32; c++)
728 {
729 int d = cd->cbits[c+cbit_space];
730 if (c == 1) d &= ~0x08;
731 start_bits[c] |= ~d;
732 }
733 break;
734
735 /* The cbit_space table has vertical tab as whitespace; we have to
736 discard it. */
737
738 case OP_WHITESPACE:
739 for (c = 0; c < 32; c++)
740 {
741 int d = cd->cbits[c+cbit_space];
742 if (c == 1) d &= ~0x08;
743 start_bits[c] |= d;
744 }
745 break;
746
747 case OP_NOT_WORDCHAR:
748 for (c = 0; c < 32; c++)
749 start_bits[c] |= ~cd->cbits[c+cbit_word];
750 break;
751
752 case OP_WORDCHAR:
753 for (c = 0; c < 32; c++)
754 start_bits[c] |= cd->cbits[c+cbit_word];
755 break;
756 }
757
758 tcode += 2;
759 break;
760
761 /* Character class where all the information is in a bit map: set the
762 bits and either carry on or not, according to the repeat count. If it was
763 a negative class, and we are operating with UTF-8 characters, any byte
764 with a value >= 0xc4 is a potentially valid starter because it starts a
765 character with a value > 255. */
766
767 case OP_NCLASS:
768 #ifdef SUPPORT_UTF8
769 if (utf8)
770 {
771 start_bits[24] |= 0xf0; /* Bits for 0xc4 - 0xc8 */
772 memset(start_bits+25, 0xff, 7); /* Bits for 0xc9 - 0xff */
773 }
774 #endif
775 /* Fall through */
776
777 case OP_CLASS:
778 {
779 tcode++;
780
781 /* In UTF-8 mode, the bits in a bit map correspond to character
782 values, not to byte values. However, the bit map we are constructing is
783 for byte values. So we have to do a conversion for characters whose
784 value is > 127. In fact, there are only two possible starting bytes for
785 characters in the range 128 - 255. */
786
787 #ifdef SUPPORT_UTF8
788 if (utf8)
789 {
790 for (c = 0; c < 16; c++) start_bits[c] |= tcode[c];
791 for (c = 128; c < 256; c++)
792 {
793 if ((tcode[c/8] && (1 << (c&7))) != 0)
794 {
795 int d = (c >> 6) | 0xc0; /* Set bit for this starter */
796 start_bits[d/8] |= (1 << (d&7)); /* and then skip on to the */
797 c = (c & 0xc0) + 0x40 - 1; /* next relevant character. */
798 }
799 }
800 }
801
802 /* In non-UTF-8 mode, the two bit maps are completely compatible. */
803
804 else
805 #endif
806 {
807 for (c = 0; c < 32; c++) start_bits[c] |= tcode[c];
808 }
809
810 /* Advance past the bit map, and act on what follows */
811
812 tcode += 32;
813 switch (*tcode)
814 {
815 case OP_CRSTAR:
816 case OP_CRMINSTAR:
817 case OP_CRQUERY:
818 case OP_CRMINQUERY:
819 tcode++;
820 break;
821
822 case OP_CRRANGE:
823 case OP_CRMINRANGE:
824 if (((tcode[1] << 8) + tcode[2]) == 0) tcode += 5;
825 else try_next = FALSE;
826 break;
827
828 default:
829 try_next = FALSE;
830 break;
831 }
832 }
833 break; /* End of bitmap class handling */
834
835 } /* End of switch */
836 } /* End of try_next loop */
837
838 code += GET(code, 1); /* Advance to next branch */
839 }
840 while (*code == OP_ALT);
841 return yield;
842 }
843
844
845
846 /*************************************************
847 * Study a compiled expression *
848 *************************************************/
849
850 /* This function is handed a compiled expression that it must study to produce
851 information that will speed up the matching. It returns a pcre_extra block
852 which then gets handed back to pcre_exec().
853
854 Arguments:
855 re points to the compiled expression
856 options contains option bits
857 errorptr points to where to place error messages;
858 set NULL unless error
859
860 Returns: pointer to a pcre_extra block, with study_data filled in and the
861 appropriate flags set;
862 NULL on error or if no optimization possible
863 */
864
865 PCRE_EXP_DEFN pcre_extra * PCRE_CALL_CONVENTION
866 pcre_study(const pcre *external_re, int options, const char **errorptr)
867 {
868 int min;
869 BOOL bits_set = FALSE;
870 uschar start_bits[32];
871 pcre_extra *extra;
872 pcre_study_data *study;
873 const uschar *tables;
874 uschar *code;
875 compile_data compile_block;
876 const real_pcre *re = (const real_pcre *)external_re;
877
878 *errorptr = NULL;
879
880 if (re == NULL || re->magic_number != MAGIC_NUMBER)
881 {
882 *errorptr = "argument is not a compiled regular expression";
883 return NULL;
884 }
885
886 if ((options & ~PUBLIC_STUDY_OPTIONS) != 0)
887 {
888 *errorptr = "unknown or incorrect option bit(s) set";
889 return NULL;
890 }
891
892 code = (uschar *)re + re->name_table_offset +
893 (re->name_count * re->name_entry_size);
894
895 /* For an anchored pattern, or an unanchored pattern that has a first char, or
896 a multiline pattern that matches only at "line starts", there is no point in
897 seeking a list of starting bytes. */
898
899 if ((re->options & PCRE_ANCHORED) == 0 &&
900 (re->flags & (PCRE_FIRSTSET|PCRE_STARTLINE)) == 0)
901 {
902 /* Set the character tables in the block that is passed around */
903
904 tables = re->tables;
905 if (tables == NULL)
906 (void)pcre_fullinfo(external_re, NULL, PCRE_INFO_DEFAULT_TABLES,
907 (void *)(&tables));
908
909 compile_block.lcc = tables + lcc_offset;
910 compile_block.fcc = tables + fcc_offset;
911 compile_block.cbits = tables + cbits_offset;
912 compile_block.ctypes = tables + ctypes_offset;
913
914 /* See if we can find a fixed set of initial characters for the pattern. */
915
916 memset(start_bits, 0, 32 * sizeof(uschar));
917 bits_set = set_start_bits(code, start_bits,
918 (re->options & PCRE_CASELESS) != 0, (re->options & PCRE_UTF8) != 0,
919 &compile_block) == SSB_DONE;
920 }
921
922 /* Find the minimum length of subject string. */
923
924 min = find_minlength(code, code, re->options);
925
926 /* Return NULL if no optimization is possible. */
927
928 if (!bits_set && min < 0) return NULL;
929
930 /* Get a pcre_extra block and a pcre_study_data block. The study data is put in
931 the latter, which is pointed to by the former, which may also get additional
932 data set later by the calling program. At the moment, the size of
933 pcre_study_data is fixed. We nevertheless save it in a field for returning via
934 the pcre_fullinfo() function so that if it becomes variable in the future, we
935 don't have to change that code. */
936
937 extra = (pcre_extra *)(pcre_malloc)
938 (sizeof(pcre_extra) + sizeof(pcre_study_data));
939
940 if (extra == NULL)
941 {
942 *errorptr = "failed to get memory";
943 return NULL;
944 }
945
946 study = (pcre_study_data *)((char *)extra + sizeof(pcre_extra));
947 extra->flags = PCRE_EXTRA_STUDY_DATA;
948 extra->study_data = study;
949
950 study->size = sizeof(pcre_study_data);
951 study->flags = 0;
952
953 if (bits_set)
954 {
955 study->flags |= PCRE_STUDY_MAPPED;
956 memcpy(study->start_bits, start_bits, sizeof(start_bits));
957 }
958
959 if (min >= 0)
960 {
961 study->flags |= PCRE_STUDY_MINLEN;
962 study->minlength = min;
963 }
964
965 return extra;
966 }
967
968 /* End of pcre_study.c */

Properties

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

webmaster@exim.org
ViewVC Help
Powered by ViewVC 1.1.12