/[pcre]/code/trunk/pcre_study.c
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Revision 524 - (hide annotations) (download)
Mon May 24 17:06:28 2010 UTC (4 years, 2 months ago) by ph10
File MIME type: text/plain
File size: 29768 byte(s)
Make pcre_study() recognize \h, \v, and \R.

1 nigel 77 /*************************************************
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 ph10 475 Copyright (c) 1997-2010 University of Cambridge
10 nigel 77
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 ph10 200 #ifdef HAVE_CONFIG_H
46 ph10 236 #include "config.h"
47 ph10 200 #endif
48 ph10 199
49 nigel 77 #include "pcre_internal.h"
50    
51 ph10 524 #define SET_BIT(c) start_bits[c/8] |= (1 << (c&7))
52 nigel 77
53 nigel 93 /* Returns from set_start_bits() */
54    
55     enum { SSB_FAIL, SSB_DONE, SSB_CONTINUE };
56    
57    
58 ph10 455
59 nigel 77 /*************************************************
60 ph10 455 * Find the minimum subject length for a group *
61     *************************************************/
62    
63     /* Scan a parenthesized group and compute the minimum length of subject that
64 ph10 461 is needed to match it. This is a lower bound; it does not mean there is a
65 ph10 455 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 ph10 461 options the compiling options
72 ph10 455
73     Returns: the minimum length
74     -1 if \C was encountered
75 ph10 461 -2 internal error (missing capturing bracket)
76 ph10 455 */
77    
78     static int
79     find_minlength(const uschar *code, const uschar *startcode, int options)
80     {
81     int length = -1;
82     BOOL utf8 = (options & PCRE_UTF8) != 0;
83     BOOL had_recurse = FALSE;
84     register int branchlength = 0;
85     register uschar *cc = (uschar *)code + 1 + LINK_SIZE;
86    
87     if (*code == OP_CBRA || *code == OP_SCBRA) cc += 2;
88    
89     /* Scan along the opcodes for this branch. If we get to the end of the
90     branch, check the length against that of the other branches. */
91    
92     for (;;)
93     {
94     int d, min;
95 ph10 461 uschar *cs, *ce;
96 ph10 455 register int op = *cc;
97 ph10 461
98 ph10 455 switch (op)
99     {
100 ph10 471 case OP_COND:
101     case OP_SCOND:
102    
103     /* If there is only one branch in a condition, the implied branch has zero
104     length, so we don't add anything. This covers the DEFINE "condition"
105     automatically. */
106    
107     cs = cc + GET(cc, 1);
108     if (*cs != OP_ALT)
109     {
110     cc = cs + 1 + LINK_SIZE;
111     break;
112     }
113    
114     /* Otherwise we can fall through and treat it the same as any other
115     subpattern. */
116    
117 ph10 455 case OP_CBRA:
118 ph10 461 case OP_SCBRA:
119 ph10 455 case OP_BRA:
120 ph10 461 case OP_SBRA:
121 ph10 455 case OP_ONCE:
122     d = find_minlength(cc, startcode, options);
123     if (d < 0) return d;
124     branchlength += d;
125     do cc += GET(cc, 1); while (*cc == OP_ALT);
126     cc += 1 + LINK_SIZE;
127     break;
128    
129     /* Reached end of a branch; if it's a ket it is the end of a nested
130     call. If it's ALT it is an alternation in a nested call. If it is
131     END it's the end of the outer call. All can be handled by the same code. */
132    
133     case OP_ALT:
134     case OP_KET:
135     case OP_KETRMAX:
136     case OP_KETRMIN:
137     case OP_END:
138 ph10 461 if (length < 0 || (!had_recurse && branchlength < length))
139 ph10 455 length = branchlength;
140     if (*cc != OP_ALT) return length;
141     cc += 1 + LINK_SIZE;
142     branchlength = 0;
143 ph10 461 had_recurse = FALSE;
144 ph10 455 break;
145    
146     /* Skip over assertive subpatterns */
147    
148     case OP_ASSERT:
149     case OP_ASSERT_NOT:
150     case OP_ASSERTBACK:
151     case OP_ASSERTBACK_NOT:
152     do cc += GET(cc, 1); while (*cc == OP_ALT);
153     /* Fall through */
154    
155     /* Skip over things that don't match chars */
156    
157     case OP_REVERSE:
158     case OP_CREF:
159 ph10 459 case OP_NCREF:
160 ph10 455 case OP_RREF:
161 ph10 459 case OP_NRREF:
162 ph10 455 case OP_DEF:
163     case OP_OPT:
164     case OP_CALLOUT:
165     case OP_SOD:
166     case OP_SOM:
167     case OP_EOD:
168     case OP_EODN:
169     case OP_CIRC:
170     case OP_DOLL:
171     case OP_NOT_WORD_BOUNDARY:
172     case OP_WORD_BOUNDARY:
173     cc += _pcre_OP_lengths[*cc];
174     break;
175 ph10 461
176 ph10 455 /* Skip over a subpattern that has a {0} or {0,x} quantifier */
177    
178     case OP_BRAZERO:
179 ph10 461 case OP_BRAMINZERO:
180 ph10 455 case OP_SKIPZERO:
181     cc += _pcre_OP_lengths[*cc];
182     do cc += GET(cc, 1); while (*cc == OP_ALT);
183     cc += 1 + LINK_SIZE;
184     break;
185    
186     /* Handle literal characters and + repetitions */
187    
188     case OP_CHAR:
189     case OP_CHARNC:
190     case OP_NOT:
191     case OP_PLUS:
192     case OP_MINPLUS:
193     case OP_POSPLUS:
194     case OP_NOTPLUS:
195     case OP_NOTMINPLUS:
196     case OP_NOTPOSPLUS:
197     branchlength++;
198     cc += 2;
199     #ifdef SUPPORT_UTF8
200     if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
201     #endif
202     break;
203 ph10 461
204 ph10 455 case OP_TYPEPLUS:
205     case OP_TYPEMINPLUS:
206 ph10 461 case OP_TYPEPOSPLUS:
207 ph10 455 branchlength++;
208     cc += (cc[1] == OP_PROP || cc[1] == OP_NOTPROP)? 4 : 2;
209     break;
210    
211     /* Handle exact repetitions. The count is already in characters, but we
212     need to skip over a multibyte character in UTF8 mode. */
213    
214     case OP_EXACT:
215 ph10 461 case OP_NOTEXACT:
216 ph10 455 branchlength += GET2(cc,1);
217     cc += 4;
218     #ifdef SUPPORT_UTF8
219     if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
220     #endif
221     break;
222    
223     case OP_TYPEEXACT:
224     branchlength += GET2(cc,1);
225     cc += (cc[3] == OP_PROP || cc[3] == OP_NOTPROP)? 6 : 4;
226     break;
227    
228     /* Handle single-char non-literal matchers */
229    
230     case OP_PROP:
231     case OP_NOTPROP:
232     cc += 2;
233     /* Fall through */
234    
235     case OP_NOT_DIGIT:
236     case OP_DIGIT:
237     case OP_NOT_WHITESPACE:
238     case OP_WHITESPACE:
239     case OP_NOT_WORDCHAR:
240     case OP_WORDCHAR:
241     case OP_ANY:
242     case OP_ALLANY:
243     case OP_EXTUNI:
244 ph10 461 case OP_HSPACE:
245 ph10 455 case OP_NOT_HSPACE:
246     case OP_VSPACE:
247 ph10 461 case OP_NOT_VSPACE:
248 ph10 455 branchlength++;
249     cc++;
250     break;
251 ph10 461
252 ph10 455 /* "Any newline" might match two characters */
253 ph10 461
254 ph10 455 case OP_ANYNL:
255     branchlength += 2;
256     cc++;
257 ph10 461 break;
258 ph10 455
259     /* The single-byte matcher means we can't proceed in UTF-8 mode */
260    
261     case OP_ANYBYTE:
262     #ifdef SUPPORT_UTF8
263     if (utf8) return -1;
264     #endif
265     branchlength++;
266     cc++;
267 ph10 461 break;
268 ph10 455
269     /* For repeated character types, we have to test for \p and \P, which have
270     an extra two bytes of parameters. */
271    
272     case OP_TYPESTAR:
273     case OP_TYPEMINSTAR:
274     case OP_TYPEQUERY:
275     case OP_TYPEMINQUERY:
276     case OP_TYPEPOSSTAR:
277     case OP_TYPEPOSQUERY:
278     if (cc[1] == OP_PROP || cc[1] == OP_NOTPROP) cc += 2;
279     cc += _pcre_OP_lengths[op];
280     break;
281    
282     case OP_TYPEUPTO:
283     case OP_TYPEMINUPTO:
284     case OP_TYPEPOSUPTO:
285     if (cc[3] == OP_PROP || cc[3] == OP_NOTPROP) cc += 2;
286     cc += _pcre_OP_lengths[op];
287     break;
288    
289     /* Check a class for variable quantification */
290    
291     #ifdef SUPPORT_UTF8
292     case OP_XCLASS:
293     cc += GET(cc, 1) - 33;
294     /* Fall through */
295     #endif
296    
297     case OP_CLASS:
298     case OP_NCLASS:
299     cc += 33;
300    
301     switch (*cc)
302     {
303     case OP_CRPLUS:
304     case OP_CRMINPLUS:
305     branchlength++;
306 ph10 461 /* Fall through */
307 ph10 455
308     case OP_CRSTAR:
309     case OP_CRMINSTAR:
310     case OP_CRQUERY:
311     case OP_CRMINQUERY:
312 ph10 461 cc++;
313 ph10 455 break;
314 ph10 461
315 ph10 455 case OP_CRRANGE:
316     case OP_CRMINRANGE:
317     branchlength += GET2(cc,1);
318     cc += 5;
319     break;
320 ph10 461
321 ph10 455 default:
322     branchlength++;
323 ph10 461 break;
324 ph10 455 }
325     break;
326 ph10 461
327     /* Backreferences and subroutine calls are treated in the same way: we find
328     the minimum length for the subpattern. A recursion, however, causes an
329 ph10 455 a flag to be set that causes the length of this branch to be ignored. The
330     logic is that a recursion can only make sense if there is another
331     alternation that stops the recursing. That will provide the minimum length
332     (when no recursion happens). A backreference within the group that it is
333 ph10 469 referencing behaves in the same way.
334    
335 ph10 467 If PCRE_JAVASCRIPT_COMPAT is set, a backreference to an unset bracket
336     matches an empty string (by default it causes a matching failure), so in
337     that case we must set the minimum length to zero. */
338 ph10 461
339 ph10 455 case OP_REF:
340 ph10 467 if ((options & PCRE_JAVASCRIPT_COMPAT) == 0)
341 ph10 469 {
342 ph10 467 ce = cs = (uschar *)_pcre_find_bracket(startcode, utf8, GET2(cc, 1));
343     if (cs == NULL) return -2;
344     do ce += GET(ce, 1); while (*ce == OP_ALT);
345     if (cc > cs && cc < ce)
346     {
347     d = 0;
348     had_recurse = TRUE;
349     }
350     else d = find_minlength(cs, startcode, options);
351 ph10 461 }
352 ph10 469 else d = 0;
353 ph10 461 cc += 3;
354 ph10 455
355     /* Handle repeated back references */
356 ph10 461
357 ph10 455 switch (*cc)
358     {
359     case OP_CRSTAR:
360     case OP_CRMINSTAR:
361     case OP_CRQUERY:
362     case OP_CRMINQUERY:
363     min = 0;
364     cc++;
365     break;
366 ph10 461
367 ph10 455 case OP_CRRANGE:
368     case OP_CRMINRANGE:
369     min = GET2(cc, 1);
370     cc += 5;
371     break;
372 ph10 461
373 ph10 455 default:
374     min = 1;
375     break;
376     }
377    
378     branchlength += min * d;
379 ph10 461 break;
380 ph10 455
381 ph10 461 case OP_RECURSE:
382 ph10 455 cs = ce = (uschar *)startcode + GET(cc, 1);
383     if (cs == NULL) return -2;
384     do ce += GET(ce, 1); while (*ce == OP_ALT);
385     if (cc > cs && cc < ce)
386 ph10 461 had_recurse = TRUE;
387     else
388 ph10 455 branchlength += find_minlength(cs, startcode, options);
389     cc += 1 + LINK_SIZE;
390     break;
391    
392     /* Anything else does not or need not match a character. We can get the
393 ph10 461 item's length from the table, but for those that can match zero occurrences
394     of a character, we must take special action for UTF-8 characters. */
395    
396 ph10 455 case OP_UPTO:
397 ph10 461 case OP_NOTUPTO:
398 ph10 455 case OP_MINUPTO:
399 ph10 461 case OP_NOTMINUPTO:
400 ph10 455 case OP_POSUPTO:
401     case OP_STAR:
402     case OP_MINSTAR:
403 ph10 461 case OP_NOTMINSTAR:
404 ph10 455 case OP_POSSTAR:
405 ph10 461 case OP_NOTPOSSTAR:
406 ph10 455 case OP_QUERY:
407     case OP_MINQUERY:
408     case OP_NOTMINQUERY:
409     case OP_POSQUERY:
410 ph10 461 case OP_NOTPOSQUERY:
411 ph10 455 cc += _pcre_OP_lengths[op];
412 ph10 461 #ifdef SUPPORT_UTF8
413 ph10 455 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
414 ph10 461 #endif
415 ph10 455 break;
416 ph10 512
417 ph10 510 /* Skip these, but we need to add in the name length. */
418 ph10 512
419 ph10 510 case OP_MARK:
420     case OP_PRUNE_ARG:
421     case OP_SKIP_ARG:
422     case OP_THEN_ARG:
423     cc += _pcre_OP_lengths[op] + cc[1];
424 ph10 512 break;
425 ph10 455
426     /* For the record, these are the opcodes that are matched by "default":
427     OP_ACCEPT, OP_CLOSE, OP_COMMIT, OP_FAIL, OP_PRUNE, OP_SET_SOM, OP_SKIP,
428     OP_THEN. */
429 ph10 461
430 ph10 455 default:
431     cc += _pcre_OP_lengths[op];
432     break;
433     }
434     }
435     /* Control never gets here */
436     }
437    
438    
439    
440     /*************************************************
441 nigel 77 * Set a bit and maybe its alternate case *
442     *************************************************/
443    
444 ph10 520 /* Given a character, set its first byte's bit in the table, and also the
445     corresponding bit for the other version of a letter if we are caseless. In
446     UTF-8 mode, for characters greater than 127, we can only do the caseless thing
447     when Unicode property support is available.
448 nigel 77
449     Arguments:
450     start_bits points to the bit map
451 ph10 520 p points to the character
452 nigel 77 caseless the caseless flag
453     cd the block with char table pointers
454 ph10 520 utf8 TRUE for UTF-8 mode
455 nigel 77
456 ph10 520 Returns: pointer after the character
457 nigel 77 */
458    
459 ph10 520 static const uschar *
460     set_table_bit(uschar *start_bits, const uschar *p, BOOL caseless,
461     compile_data *cd, BOOL utf8)
462 nigel 77 {
463 ph10 520 unsigned int c = *p;
464    
465 ph10 524 SET_BIT(c);
466    
467 ph10 520 #ifdef SUPPORT_UTF8
468     if (utf8 && c > 127)
469     {
470     GETCHARINC(c, p);
471     #ifdef SUPPORT_UCP
472     if (caseless)
473     {
474     uschar buff[8];
475     c = UCD_OTHERCASE(c);
476     (void)_pcre_ord2utf8(c, buff);
477 ph10 524 SET_BIT(buff[0]);
478 ph10 520 }
479     #endif
480     return p;
481     }
482     #endif
483    
484     /* Not UTF-8 mode, or character is less than 127. */
485    
486 ph10 524 if (caseless && (cd->ctypes[c] & ctype_letter) != 0) SET_BIT(cd->fcc[c]);
487 ph10 520 return p + 1;
488 nigel 77 }
489    
490    
491    
492     /*************************************************
493 nigel 93 * Create bitmap of starting bytes *
494 nigel 77 *************************************************/
495    
496 nigel 93 /* This function scans a compiled unanchored expression recursively and
497     attempts to build a bitmap of the set of possible starting bytes. As time goes
498     by, we may be able to get more clever at doing this. The SSB_CONTINUE return is
499     useful for parenthesized groups in patterns such as (a*)b where the group
500     provides some optional starting bytes but scanning must continue at the outer
501     level to find at least one mandatory byte. At the outermost level, this
502     function fails unless the result is SSB_DONE.
503 nigel 77
504     Arguments:
505     code points to an expression
506     start_bits points to a 32-byte table, initialized to 0
507     caseless the current state of the caseless flag
508     utf8 TRUE if in UTF-8 mode
509     cd the block with char table pointers
510    
511 nigel 93 Returns: SSB_FAIL => Failed to find any starting bytes
512     SSB_DONE => Found mandatory starting bytes
513     SSB_CONTINUE => Found optional starting bytes
514 nigel 77 */
515    
516 nigel 93 static int
517 nigel 77 set_start_bits(const uschar *code, uschar *start_bits, BOOL caseless,
518     BOOL utf8, compile_data *cd)
519     {
520     register int c;
521 nigel 93 int yield = SSB_DONE;
522 nigel 77
523 nigel 91 #if 0
524     /* ========================================================================= */
525     /* The following comment and code was inserted in January 1999. In May 2006,
526     when it was observed to cause compiler warnings about unused values, I took it
527     out again. If anybody is still using OS/2, they will have to put it back
528     manually. */
529    
530 nigel 77 /* This next statement and the later reference to dummy are here in order to
531     trick the optimizer of the IBM C compiler for OS/2 into generating correct
532     code. Apparently IBM isn't going to fix the problem, and we would rather not
533     disable optimization (in this module it actually makes a big difference, and
534     the pcre module can use all the optimization it can get). */
535    
536     volatile int dummy;
537 nigel 91 /* ========================================================================= */
538     #endif
539 nigel 77
540     do
541     {
542 nigel 93 const uschar *tcode = code + (((int)*code == OP_CBRA)? 3:1) + LINK_SIZE;
543 nigel 77 BOOL try_next = TRUE;
544    
545 nigel 93 while (try_next) /* Loop for items in this branch */
546 nigel 77 {
547 nigel 93 int rc;
548     switch(*tcode)
549 nigel 77 {
550 nigel 93 /* Fail if we reach something we don't understand */
551 nigel 77
552     default:
553 nigel 93 return SSB_FAIL;
554 nigel 77
555 nigel 93 /* If we hit a bracket or a positive lookahead assertion, recurse to set
556     bits from within the subpattern. If it can't find anything, we have to
557     give up. If it finds some mandatory character(s), we are done for this
558     branch. Otherwise, carry on scanning after the subpattern. */
559    
560     case OP_BRA:
561     case OP_SBRA:
562     case OP_CBRA:
563     case OP_SCBRA:
564     case OP_ONCE:
565     case OP_ASSERT:
566     rc = set_start_bits(tcode, start_bits, caseless, utf8, cd);
567     if (rc == SSB_FAIL) return SSB_FAIL;
568     if (rc == SSB_DONE) try_next = FALSE; else
569     {
570     do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
571     tcode += 1 + LINK_SIZE;
572     }
573     break;
574    
575     /* If we hit ALT or KET, it means we haven't found anything mandatory in
576     this branch, though we might have found something optional. For ALT, we
577     continue with the next alternative, but we have to arrange that the final
578     result from subpattern is SSB_CONTINUE rather than SSB_DONE. For KET,
579     return SSB_CONTINUE: if this is the top level, that indicates failure,
580     but after a nested subpattern, it causes scanning to continue. */
581    
582     case OP_ALT:
583     yield = SSB_CONTINUE;
584     try_next = FALSE;
585     break;
586    
587     case OP_KET:
588     case OP_KETRMAX:
589     case OP_KETRMIN:
590     return SSB_CONTINUE;
591    
592 nigel 77 /* Skip over callout */
593    
594     case OP_CALLOUT:
595     tcode += 2 + 2*LINK_SIZE;
596     break;
597    
598     /* Skip over lookbehind and negative lookahead assertions */
599    
600     case OP_ASSERT_NOT:
601     case OP_ASSERTBACK:
602     case OP_ASSERTBACK_NOT:
603     do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
604 nigel 93 tcode += 1 + LINK_SIZE;
605 nigel 77 break;
606    
607     /* Skip over an option setting, changing the caseless flag */
608    
609     case OP_OPT:
610     caseless = (tcode[1] & PCRE_CASELESS) != 0;
611     tcode += 2;
612     break;
613    
614     /* BRAZERO does the bracket, but carries on. */
615    
616     case OP_BRAZERO:
617     case OP_BRAMINZERO:
618 nigel 93 if (set_start_bits(++tcode, start_bits, caseless, utf8, cd) == SSB_FAIL)
619     return SSB_FAIL;
620 nigel 91 /* =========================================================================
621     See the comment at the head of this function concerning the next line,
622     which was an old fudge for the benefit of OS/2.
623 nigel 77 dummy = 1;
624 nigel 91 ========================================================================= */
625 nigel 77 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
626 nigel 93 tcode += 1 + LINK_SIZE;
627 nigel 77 break;
628    
629 ph10 335 /* SKIPZERO skips the bracket. */
630    
631     case OP_SKIPZERO:
632 ph10 358 tcode++;
633 ph10 335 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
634     tcode += 1 + LINK_SIZE;
635     break;
636    
637 nigel 77 /* Single-char * or ? sets the bit and tries the next item */
638    
639     case OP_STAR:
640     case OP_MINSTAR:
641 nigel 93 case OP_POSSTAR:
642 nigel 77 case OP_QUERY:
643     case OP_MINQUERY:
644 nigel 93 case OP_POSQUERY:
645 ph10 520 tcode = set_table_bit(start_bits, tcode + 1, caseless, cd, utf8);
646 nigel 77 break;
647    
648     /* Single-char upto sets the bit and tries the next */
649    
650     case OP_UPTO:
651     case OP_MINUPTO:
652 nigel 93 case OP_POSUPTO:
653 ph10 520 tcode = set_table_bit(start_bits, tcode + 3, caseless, cd, utf8);
654 nigel 77 break;
655    
656     /* At least one single char sets the bit and stops */
657    
658     case OP_EXACT: /* Fall through */
659     tcode += 2;
660    
661     case OP_CHAR:
662     case OP_CHARNC:
663     case OP_PLUS:
664     case OP_MINPLUS:
665 nigel 93 case OP_POSPLUS:
666 ph10 520 (void)set_table_bit(start_bits, tcode + 1, caseless, cd, utf8);
667 nigel 77 try_next = FALSE;
668     break;
669 ph10 524
670     /* Special spacing and line-terminating items. These recognize specific
671     lists of characters. The difference between VSPACE and ANYNL is that the
672     latter can match the two-character CRLF sequence, but that is not
673     relevant for finding the first character, so their code here is
674     identical. */
675    
676     case OP_HSPACE:
677     SET_BIT(0x09);
678     SET_BIT(0x20);
679     SET_BIT(0xA0);
680     if (utf8)
681     {
682     SET_BIT(0xE1); /* For U+1680, U+180E */
683     SET_BIT(0xE2); /* For U+2000 - U+200A, U+202F, U+205F */
684     SET_BIT(0xE3); /* For U+3000 */
685     }
686     try_next = FALSE;
687     break;
688 nigel 77
689 ph10 524 case OP_ANYNL:
690     case OP_VSPACE:
691     SET_BIT(0x0A);
692     SET_BIT(0x0B);
693     SET_BIT(0x0C);
694     SET_BIT(0x0D);
695     SET_BIT(0x85);
696     if (utf8) SET_BIT(0xE2); /* For U+2028, U+2029 */
697     try_next = FALSE;
698     break;
699    
700 ph10 520 /* Single character types set the bits and stop. Note that if PCRE_UCP
701     is set, we do not see these op codes because \d etc are converted to
702     properties. Therefore, these apply in the case when only ASCII characters
703     are recognized to match the types. */
704 nigel 77
705     case OP_NOT_DIGIT:
706     for (c = 0; c < 32; c++)
707     start_bits[c] |= ~cd->cbits[c+cbit_digit];
708     try_next = FALSE;
709     break;
710    
711     case OP_DIGIT:
712     for (c = 0; c < 32; c++)
713     start_bits[c] |= cd->cbits[c+cbit_digit];
714     try_next = FALSE;
715     break;
716    
717 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
718     discard it. */
719    
720 nigel 77 case OP_NOT_WHITESPACE:
721     for (c = 0; c < 32; c++)
722 nigel 91 {
723     int d = cd->cbits[c+cbit_space];
724     if (c == 1) d &= ~0x08;
725     start_bits[c] |= ~d;
726     }
727 nigel 77 try_next = FALSE;
728     break;
729    
730 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
731     discard it. */
732    
733 nigel 77 case OP_WHITESPACE:
734     for (c = 0; c < 32; c++)
735 nigel 91 {
736     int d = cd->cbits[c+cbit_space];
737     if (c == 1) d &= ~0x08;
738     start_bits[c] |= d;
739     }
740 nigel 77 try_next = FALSE;
741     break;
742    
743     case OP_NOT_WORDCHAR:
744     for (c = 0; c < 32; c++)
745     start_bits[c] |= ~cd->cbits[c+cbit_word];
746     try_next = FALSE;
747     break;
748    
749     case OP_WORDCHAR:
750     for (c = 0; c < 32; c++)
751     start_bits[c] |= cd->cbits[c+cbit_word];
752     try_next = FALSE;
753     break;
754    
755     /* One or more character type fudges the pointer and restarts, knowing
756     it will hit a single character type and stop there. */
757    
758     case OP_TYPEPLUS:
759     case OP_TYPEMINPLUS:
760 ph10 524 case OP_TYPEPOSPLUS:
761 nigel 77 tcode++;
762     break;
763    
764     case OP_TYPEEXACT:
765     tcode += 3;
766     break;
767    
768     /* Zero or more repeats of character types set the bits and then
769     try again. */
770    
771     case OP_TYPEUPTO:
772     case OP_TYPEMINUPTO:
773 nigel 93 case OP_TYPEPOSUPTO:
774 nigel 77 tcode += 2; /* Fall through */
775    
776     case OP_TYPESTAR:
777     case OP_TYPEMINSTAR:
778 nigel 93 case OP_TYPEPOSSTAR:
779 nigel 77 case OP_TYPEQUERY:
780     case OP_TYPEMINQUERY:
781 nigel 93 case OP_TYPEPOSQUERY:
782 nigel 77 switch(tcode[1])
783     {
784 ph10 523 default:
785 nigel 77 case OP_ANY:
786 ph10 345 case OP_ALLANY:
787 nigel 93 return SSB_FAIL;
788 ph10 524
789     case OP_HSPACE:
790     SET_BIT(0x09);
791     SET_BIT(0x20);
792     SET_BIT(0xA0);
793     if (utf8)
794     {
795     SET_BIT(0xE1); /* For U+1680, U+180E */
796     SET_BIT(0xE2); /* For U+2000 - U+200A, U+202F, U+205F */
797     SET_BIT(0xE3); /* For U+3000 */
798     }
799     break;
800    
801     case OP_ANYNL:
802     case OP_VSPACE:
803     SET_BIT(0x0A);
804     SET_BIT(0x0B);
805     SET_BIT(0x0C);
806     SET_BIT(0x0D);
807     SET_BIT(0x85);
808     if (utf8) SET_BIT(0xE2); /* For U+2028, U+2029 */
809     break;
810    
811 nigel 77 case OP_NOT_DIGIT:
812     for (c = 0; c < 32; c++)
813     start_bits[c] |= ~cd->cbits[c+cbit_digit];
814     break;
815    
816     case OP_DIGIT:
817     for (c = 0; c < 32; c++)
818     start_bits[c] |= cd->cbits[c+cbit_digit];
819     break;
820    
821 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
822     discard it. */
823    
824 nigel 77 case OP_NOT_WHITESPACE:
825     for (c = 0; c < 32; c++)
826 nigel 91 {
827     int d = cd->cbits[c+cbit_space];
828     if (c == 1) d &= ~0x08;
829     start_bits[c] |= ~d;
830     }
831 nigel 77 break;
832    
833 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
834     discard it. */
835    
836 nigel 77 case OP_WHITESPACE:
837     for (c = 0; c < 32; c++)
838 nigel 91 {
839     int d = cd->cbits[c+cbit_space];
840     if (c == 1) d &= ~0x08;
841     start_bits[c] |= d;
842     }
843 nigel 77 break;
844    
845     case OP_NOT_WORDCHAR:
846     for (c = 0; c < 32; c++)
847     start_bits[c] |= ~cd->cbits[c+cbit_word];
848     break;
849    
850     case OP_WORDCHAR:
851     for (c = 0; c < 32; c++)
852     start_bits[c] |= cd->cbits[c+cbit_word];
853     break;
854     }
855    
856     tcode += 2;
857     break;
858    
859     /* Character class where all the information is in a bit map: set the
860     bits and either carry on or not, according to the repeat count. If it was
861     a negative class, and we are operating with UTF-8 characters, any byte
862     with a value >= 0xc4 is a potentially valid starter because it starts a
863     character with a value > 255. */
864    
865     case OP_NCLASS:
866 ph10 111 #ifdef SUPPORT_UTF8
867 nigel 77 if (utf8)
868     {
869     start_bits[24] |= 0xf0; /* Bits for 0xc4 - 0xc8 */
870     memset(start_bits+25, 0xff, 7); /* Bits for 0xc9 - 0xff */
871     }
872 ph10 111 #endif
873 nigel 77 /* Fall through */
874    
875     case OP_CLASS:
876     {
877     tcode++;
878    
879     /* In UTF-8 mode, the bits in a bit map correspond to character
880     values, not to byte values. However, the bit map we are constructing is
881     for byte values. So we have to do a conversion for characters whose
882     value is > 127. In fact, there are only two possible starting bytes for
883     characters in the range 128 - 255. */
884    
885 ph10 107 #ifdef SUPPORT_UTF8
886 nigel 77 if (utf8)
887     {
888     for (c = 0; c < 16; c++) start_bits[c] |= tcode[c];
889     for (c = 128; c < 256; c++)
890     {
891     if ((tcode[c/8] && (1 << (c&7))) != 0)
892     {
893     int d = (c >> 6) | 0xc0; /* Set bit for this starter */
894     start_bits[d/8] |= (1 << (d&7)); /* and then skip on to the */
895     c = (c & 0xc0) + 0x40 - 1; /* next relevant character. */
896     }
897     }
898     }
899    
900     /* In non-UTF-8 mode, the two bit maps are completely compatible. */
901    
902     else
903 ph10 111 #endif
904 nigel 77 {
905     for (c = 0; c < 32; c++) start_bits[c] |= tcode[c];
906     }
907    
908     /* Advance past the bit map, and act on what follows */
909    
910     tcode += 32;
911     switch (*tcode)
912     {
913     case OP_CRSTAR:
914     case OP_CRMINSTAR:
915     case OP_CRQUERY:
916     case OP_CRMINQUERY:
917     tcode++;
918     break;
919    
920     case OP_CRRANGE:
921     case OP_CRMINRANGE:
922     if (((tcode[1] << 8) + tcode[2]) == 0) tcode += 5;
923     else try_next = FALSE;
924     break;
925    
926     default:
927     try_next = FALSE;
928     break;
929     }
930     }
931     break; /* End of bitmap class handling */
932    
933     } /* End of switch */
934     } /* End of try_next loop */
935    
936     code += GET(code, 1); /* Advance to next branch */
937     }
938     while (*code == OP_ALT);
939 nigel 93 return yield;
940 nigel 77 }
941    
942    
943    
944     /*************************************************
945     * Study a compiled expression *
946     *************************************************/
947    
948     /* This function is handed a compiled expression that it must study to produce
949     information that will speed up the matching. It returns a pcre_extra block
950     which then gets handed back to pcre_exec().
951    
952     Arguments:
953     re points to the compiled expression
954     options contains option bits
955     errorptr points to where to place error messages;
956     set NULL unless error
957    
958     Returns: pointer to a pcre_extra block, with study_data filled in and the
959 ph10 455 appropriate flags set;
960 nigel 77 NULL on error or if no optimization possible
961     */
962    
963 ph10 359 PCRE_EXP_DEFN pcre_extra * PCRE_CALL_CONVENTION
964 nigel 77 pcre_study(const pcre *external_re, int options, const char **errorptr)
965     {
966 ph10 455 int min;
967     BOOL bits_set = FALSE;
968 nigel 77 uschar start_bits[32];
969     pcre_extra *extra;
970     pcre_study_data *study;
971     const uschar *tables;
972 nigel 91 uschar *code;
973     compile_data compile_block;
974 nigel 77 const real_pcre *re = (const real_pcre *)external_re;
975    
976     *errorptr = NULL;
977    
978     if (re == NULL || re->magic_number != MAGIC_NUMBER)
979     {
980     *errorptr = "argument is not a compiled regular expression";
981     return NULL;
982     }
983    
984     if ((options & ~PUBLIC_STUDY_OPTIONS) != 0)
985     {
986     *errorptr = "unknown or incorrect option bit(s) set";
987     return NULL;
988     }
989    
990 nigel 91 code = (uschar *)re + re->name_table_offset +
991     (re->name_count * re->name_entry_size);
992    
993 nigel 77 /* For an anchored pattern, or an unanchored pattern that has a first char, or
994 ph10 461 a multiline pattern that matches only at "line starts", there is no point in
995 ph10 455 seeking a list of starting bytes. */
996 nigel 77
997 ph10 455 if ((re->options & PCRE_ANCHORED) == 0 &&
998     (re->flags & (PCRE_FIRSTSET|PCRE_STARTLINE)) == 0)
999     {
1000     /* Set the character tables in the block that is passed around */
1001 ph10 461
1002 ph10 455 tables = re->tables;
1003     if (tables == NULL)
1004     (void)pcre_fullinfo(external_re, NULL, PCRE_INFO_DEFAULT_TABLES,
1005     (void *)(&tables));
1006 ph10 461
1007 ph10 455 compile_block.lcc = tables + lcc_offset;
1008     compile_block.fcc = tables + fcc_offset;
1009     compile_block.cbits = tables + cbits_offset;
1010     compile_block.ctypes = tables + ctypes_offset;
1011 ph10 461
1012 ph10 455 /* See if we can find a fixed set of initial characters for the pattern. */
1013 ph10 461
1014 ph10 455 memset(start_bits, 0, 32 * sizeof(uschar));
1015 ph10 461 bits_set = set_start_bits(code, start_bits,
1016     (re->options & PCRE_CASELESS) != 0, (re->options & PCRE_UTF8) != 0,
1017 ph10 455 &compile_block) == SSB_DONE;
1018     }
1019 ph10 461
1020 ph10 455 /* Find the minimum length of subject string. */
1021 nigel 77
1022 ph10 455 min = find_minlength(code, code, re->options);
1023 nigel 77
1024 ph10 455 /* Return NULL if no optimization is possible. */
1025 nigel 77
1026 ph10 455 if (!bits_set && min < 0) return NULL;
1027 nigel 77
1028     /* Get a pcre_extra block and a pcre_study_data block. The study data is put in
1029     the latter, which is pointed to by the former, which may also get additional
1030     data set later by the calling program. At the moment, the size of
1031     pcre_study_data is fixed. We nevertheless save it in a field for returning via
1032     the pcre_fullinfo() function so that if it becomes variable in the future, we
1033     don't have to change that code. */
1034    
1035     extra = (pcre_extra *)(pcre_malloc)
1036     (sizeof(pcre_extra) + sizeof(pcre_study_data));
1037    
1038     if (extra == NULL)
1039     {
1040     *errorptr = "failed to get memory";
1041     return NULL;
1042     }
1043    
1044     study = (pcre_study_data *)((char *)extra + sizeof(pcre_extra));
1045     extra->flags = PCRE_EXTRA_STUDY_DATA;
1046     extra->study_data = study;
1047    
1048     study->size = sizeof(pcre_study_data);
1049 ph10 455 study->flags = 0;
1050 nigel 77
1051 ph10 455 if (bits_set)
1052     {
1053     study->flags |= PCRE_STUDY_MAPPED;
1054     memcpy(study->start_bits, start_bits, sizeof(start_bits));
1055     }
1056 ph10 461
1057 ph10 455 if (min >= 0)
1058     {
1059     study->flags |= PCRE_STUDY_MINLEN;
1060     study->minlength = min;
1061 ph10 461 }
1062 ph10 455
1063 nigel 77 return extra;
1064     }
1065    
1066     /* End of pcre_study.c */

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