/[pcre]/code/trunk/pcre_study.c
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Revision 510 - (hide annotations) (download)
Sat Mar 27 17:45:29 2010 UTC (4 years ago) by ph10
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Add support for *MARK and names for *PRUNE, *SKIP, *THEN.

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    
52 nigel 93 /* Returns from set_start_bits() */
53    
54     enum { SSB_FAIL, SSB_DONE, SSB_CONTINUE };
55    
56    
57 ph10 455
58 nigel 77 /*************************************************
59 ph10 455 * Find the minimum subject length for a group *
60     *************************************************/
61    
62     /* Scan a parenthesized group and compute the minimum length of subject that
63 ph10 461 is needed to match it. This is a lower bound; it does not mean there is a
64 ph10 455 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 ph10 461 options the compiling options
71 ph10 455
72     Returns: the minimum length
73     -1 if \C was encountered
74 ph10 461 -2 internal error (missing capturing bracket)
75 ph10 455 */
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 ph10 461 uschar *cs, *ce;
95 ph10 455 register int op = *cc;
96 ph10 461
97 ph10 455 switch (op)
98     {
99 ph10 471 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 ph10 455 case OP_CBRA:
117 ph10 461 case OP_SCBRA:
118 ph10 455 case OP_BRA:
119 ph10 461 case OP_SBRA:
120 ph10 455 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 ph10 461 if (length < 0 || (!had_recurse && branchlength < length))
138 ph10 455 length = branchlength;
139     if (*cc != OP_ALT) return length;
140     cc += 1 + LINK_SIZE;
141     branchlength = 0;
142 ph10 461 had_recurse = FALSE;
143 ph10 455 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 ph10 459 case OP_NCREF:
159 ph10 455 case OP_RREF:
160 ph10 459 case OP_NRREF:
161 ph10 455 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 ph10 461
175 ph10 455 /* Skip over a subpattern that has a {0} or {0,x} quantifier */
176    
177     case OP_BRAZERO:
178 ph10 461 case OP_BRAMINZERO:
179 ph10 455 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 ph10 461
203 ph10 455 case OP_TYPEPLUS:
204     case OP_TYPEMINPLUS:
205 ph10 461 case OP_TYPEPOSPLUS:
206 ph10 455 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 ph10 461 case OP_NOTEXACT:
215 ph10 455 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 ph10 461 case OP_HSPACE:
244 ph10 455 case OP_NOT_HSPACE:
245     case OP_VSPACE:
246 ph10 461 case OP_NOT_VSPACE:
247 ph10 455 branchlength++;
248     cc++;
249     break;
250 ph10 461
251 ph10 455 /* "Any newline" might match two characters */
252 ph10 461
253 ph10 455 case OP_ANYNL:
254     branchlength += 2;
255     cc++;
256 ph10 461 break;
257 ph10 455
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 ph10 461 break;
267 ph10 455
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 ph10 461 /* Fall through */
306 ph10 455
307     case OP_CRSTAR:
308     case OP_CRMINSTAR:
309     case OP_CRQUERY:
310     case OP_CRMINQUERY:
311 ph10 461 cc++;
312 ph10 455 break;
313 ph10 461
314 ph10 455 case OP_CRRANGE:
315     case OP_CRMINRANGE:
316     branchlength += GET2(cc,1);
317     cc += 5;
318     break;
319 ph10 461
320 ph10 455 default:
321     branchlength++;
322 ph10 461 break;
323 ph10 455 }
324     break;
325 ph10 461
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 ph10 455 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 ph10 469 referencing behaves in the same way.
333    
334 ph10 467 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 ph10 461
338 ph10 455 case OP_REF:
339 ph10 467 if ((options & PCRE_JAVASCRIPT_COMPAT) == 0)
340 ph10 469 {
341 ph10 467 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 ph10 461 }
351 ph10 469 else d = 0;
352 ph10 461 cc += 3;
353 ph10 455
354     /* Handle repeated back references */
355 ph10 461
356 ph10 455 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 ph10 461
366 ph10 455 case OP_CRRANGE:
367     case OP_CRMINRANGE:
368     min = GET2(cc, 1);
369     cc += 5;
370     break;
371 ph10 461
372 ph10 455 default:
373     min = 1;
374     break;
375     }
376    
377     branchlength += min * d;
378 ph10 461 break;
379 ph10 455
380 ph10 461 case OP_RECURSE:
381 ph10 455 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 ph10 461 had_recurse = TRUE;
386     else
387 ph10 455 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 ph10 461 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 ph10 455 case OP_UPTO:
396 ph10 461 case OP_NOTUPTO:
397 ph10 455 case OP_MINUPTO:
398 ph10 461 case OP_NOTMINUPTO:
399 ph10 455 case OP_POSUPTO:
400     case OP_STAR:
401     case OP_MINSTAR:
402 ph10 461 case OP_NOTMINSTAR:
403 ph10 455 case OP_POSSTAR:
404 ph10 461 case OP_NOTPOSSTAR:
405 ph10 455 case OP_QUERY:
406     case OP_MINQUERY:
407     case OP_NOTMINQUERY:
408     case OP_POSQUERY:
409 ph10 461 case OP_NOTPOSQUERY:
410 ph10 455 cc += _pcre_OP_lengths[op];
411 ph10 461 #ifdef SUPPORT_UTF8
412 ph10 455 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
413 ph10 461 #endif
414 ph10 455 break;
415 ph10 510
416     /* Skip these, but we need to add in the name length. */
417    
418     case OP_MARK:
419     case OP_PRUNE_ARG:
420     case OP_SKIP_ARG:
421     case OP_THEN_ARG:
422     cc += _pcre_OP_lengths[op] + cc[1];
423     break;
424 ph10 455
425     /* For the record, these are the opcodes that are matched by "default":
426     OP_ACCEPT, OP_CLOSE, OP_COMMIT, OP_FAIL, OP_PRUNE, OP_SET_SOM, OP_SKIP,
427     OP_THEN. */
428 ph10 461
429 ph10 455 default:
430     cc += _pcre_OP_lengths[op];
431     break;
432     }
433     }
434     /* Control never gets here */
435     }
436    
437    
438    
439     /*************************************************
440 nigel 77 * Set a bit and maybe its alternate case *
441     *************************************************/
442    
443     /* Given a character, set its bit in the table, and also the bit for the other
444     version of a letter if we are caseless.
445    
446     Arguments:
447     start_bits points to the bit map
448     c is the character
449     caseless the caseless flag
450     cd the block with char table pointers
451    
452     Returns: nothing
453     */
454    
455     static void
456 ph10 487 set_table_bit(uschar *start_bits, unsigned int c, BOOL caseless,
457 ph10 475 compile_data *cd)
458 nigel 77 {
459     start_bits[c/8] |= (1 << (c&7));
460     if (caseless && (cd->ctypes[c] & ctype_letter) != 0)
461     start_bits[cd->fcc[c]/8] |= (1 << (cd->fcc[c]&7));
462     }
463    
464    
465    
466     /*************************************************
467 nigel 93 * Create bitmap of starting bytes *
468 nigel 77 *************************************************/
469    
470 nigel 93 /* This function scans a compiled unanchored expression recursively and
471     attempts to build a bitmap of the set of possible starting bytes. As time goes
472     by, we may be able to get more clever at doing this. The SSB_CONTINUE return is
473     useful for parenthesized groups in patterns such as (a*)b where the group
474     provides some optional starting bytes but scanning must continue at the outer
475     level to find at least one mandatory byte. At the outermost level, this
476     function fails unless the result is SSB_DONE.
477 nigel 77
478     Arguments:
479     code points to an expression
480     start_bits points to a 32-byte table, initialized to 0
481     caseless the current state of the caseless flag
482     utf8 TRUE if in UTF-8 mode
483     cd the block with char table pointers
484    
485 nigel 93 Returns: SSB_FAIL => Failed to find any starting bytes
486     SSB_DONE => Found mandatory starting bytes
487     SSB_CONTINUE => Found optional starting bytes
488 nigel 77 */
489    
490 nigel 93 static int
491 nigel 77 set_start_bits(const uschar *code, uschar *start_bits, BOOL caseless,
492     BOOL utf8, compile_data *cd)
493     {
494     register int c;
495 nigel 93 int yield = SSB_DONE;
496 nigel 77
497 nigel 91 #if 0
498     /* ========================================================================= */
499     /* The following comment and code was inserted in January 1999. In May 2006,
500     when it was observed to cause compiler warnings about unused values, I took it
501     out again. If anybody is still using OS/2, they will have to put it back
502     manually. */
503    
504 nigel 77 /* This next statement and the later reference to dummy are here in order to
505     trick the optimizer of the IBM C compiler for OS/2 into generating correct
506     code. Apparently IBM isn't going to fix the problem, and we would rather not
507     disable optimization (in this module it actually makes a big difference, and
508     the pcre module can use all the optimization it can get). */
509    
510     volatile int dummy;
511 nigel 91 /* ========================================================================= */
512     #endif
513 nigel 77
514     do
515     {
516 nigel 93 const uschar *tcode = code + (((int)*code == OP_CBRA)? 3:1) + LINK_SIZE;
517 nigel 77 BOOL try_next = TRUE;
518    
519 nigel 93 while (try_next) /* Loop for items in this branch */
520 nigel 77 {
521 nigel 93 int rc;
522     switch(*tcode)
523 nigel 77 {
524 nigel 93 /* Fail if we reach something we don't understand */
525 nigel 77
526     default:
527 nigel 93 return SSB_FAIL;
528 nigel 77
529 nigel 93 /* If we hit a bracket or a positive lookahead assertion, recurse to set
530     bits from within the subpattern. If it can't find anything, we have to
531     give up. If it finds some mandatory character(s), we are done for this
532     branch. Otherwise, carry on scanning after the subpattern. */
533    
534     case OP_BRA:
535     case OP_SBRA:
536     case OP_CBRA:
537     case OP_SCBRA:
538     case OP_ONCE:
539     case OP_ASSERT:
540     rc = set_start_bits(tcode, start_bits, caseless, utf8, cd);
541     if (rc == SSB_FAIL) return SSB_FAIL;
542     if (rc == SSB_DONE) try_next = FALSE; else
543     {
544     do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
545     tcode += 1 + LINK_SIZE;
546     }
547     break;
548    
549     /* If we hit ALT or KET, it means we haven't found anything mandatory in
550     this branch, though we might have found something optional. For ALT, we
551     continue with the next alternative, but we have to arrange that the final
552     result from subpattern is SSB_CONTINUE rather than SSB_DONE. For KET,
553     return SSB_CONTINUE: if this is the top level, that indicates failure,
554     but after a nested subpattern, it causes scanning to continue. */
555    
556     case OP_ALT:
557     yield = SSB_CONTINUE;
558     try_next = FALSE;
559     break;
560    
561     case OP_KET:
562     case OP_KETRMAX:
563     case OP_KETRMIN:
564     return SSB_CONTINUE;
565    
566 nigel 77 /* Skip over callout */
567    
568     case OP_CALLOUT:
569     tcode += 2 + 2*LINK_SIZE;
570     break;
571    
572     /* Skip over lookbehind and negative lookahead assertions */
573    
574     case OP_ASSERT_NOT:
575     case OP_ASSERTBACK:
576     case OP_ASSERTBACK_NOT:
577     do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
578 nigel 93 tcode += 1 + LINK_SIZE;
579 nigel 77 break;
580    
581     /* Skip over an option setting, changing the caseless flag */
582    
583     case OP_OPT:
584     caseless = (tcode[1] & PCRE_CASELESS) != 0;
585     tcode += 2;
586     break;
587    
588     /* BRAZERO does the bracket, but carries on. */
589    
590     case OP_BRAZERO:
591     case OP_BRAMINZERO:
592 nigel 93 if (set_start_bits(++tcode, start_bits, caseless, utf8, cd) == SSB_FAIL)
593     return SSB_FAIL;
594 nigel 91 /* =========================================================================
595     See the comment at the head of this function concerning the next line,
596     which was an old fudge for the benefit of OS/2.
597 nigel 77 dummy = 1;
598 nigel 91 ========================================================================= */
599 nigel 77 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
600 nigel 93 tcode += 1 + LINK_SIZE;
601 nigel 77 break;
602    
603 ph10 335 /* SKIPZERO skips the bracket. */
604    
605     case OP_SKIPZERO:
606 ph10 358 tcode++;
607 ph10 335 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
608     tcode += 1 + LINK_SIZE;
609     break;
610    
611 nigel 77 /* Single-char * or ? sets the bit and tries the next item */
612    
613     case OP_STAR:
614     case OP_MINSTAR:
615 nigel 93 case OP_POSSTAR:
616 nigel 77 case OP_QUERY:
617     case OP_MINQUERY:
618 nigel 93 case OP_POSQUERY:
619 ph10 475 set_table_bit(start_bits, tcode[1], caseless, cd);
620 nigel 77 tcode += 2;
621     #ifdef SUPPORT_UTF8
622 nigel 93 if (utf8 && tcode[-1] >= 0xc0)
623     tcode += _pcre_utf8_table4[tcode[-1] & 0x3f];
624 nigel 77 #endif
625     break;
626    
627     /* Single-char upto sets the bit and tries the next */
628    
629     case OP_UPTO:
630     case OP_MINUPTO:
631 nigel 93 case OP_POSUPTO:
632 ph10 475 set_table_bit(start_bits, tcode[3], caseless, cd);
633 nigel 77 tcode += 4;
634     #ifdef SUPPORT_UTF8
635 nigel 93 if (utf8 && tcode[-1] >= 0xc0)
636     tcode += _pcre_utf8_table4[tcode[-1] & 0x3f];
637 nigel 77 #endif
638     break;
639    
640     /* At least one single char sets the bit and stops */
641    
642     case OP_EXACT: /* Fall through */
643     tcode += 2;
644    
645     case OP_CHAR:
646     case OP_CHARNC:
647     case OP_PLUS:
648     case OP_MINPLUS:
649 nigel 93 case OP_POSPLUS:
650 ph10 475 set_table_bit(start_bits, tcode[1], caseless, cd);
651 nigel 77 try_next = FALSE;
652     break;
653    
654     /* Single character type sets the bits and stops */
655    
656     case OP_NOT_DIGIT:
657     for (c = 0; c < 32; c++)
658     start_bits[c] |= ~cd->cbits[c+cbit_digit];
659     try_next = FALSE;
660     break;
661    
662     case OP_DIGIT:
663     for (c = 0; c < 32; c++)
664     start_bits[c] |= cd->cbits[c+cbit_digit];
665     try_next = FALSE;
666     break;
667    
668 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
669     discard it. */
670    
671 nigel 77 case OP_NOT_WHITESPACE:
672     for (c = 0; c < 32; c++)
673 nigel 91 {
674     int d = cd->cbits[c+cbit_space];
675     if (c == 1) d &= ~0x08;
676     start_bits[c] |= ~d;
677     }
678 nigel 77 try_next = FALSE;
679     break;
680    
681 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
682     discard it. */
683    
684 nigel 77 case OP_WHITESPACE:
685     for (c = 0; c < 32; c++)
686 nigel 91 {
687     int d = cd->cbits[c+cbit_space];
688     if (c == 1) d &= ~0x08;
689     start_bits[c] |= d;
690     }
691 nigel 77 try_next = FALSE;
692     break;
693    
694     case OP_NOT_WORDCHAR:
695     for (c = 0; c < 32; c++)
696     start_bits[c] |= ~cd->cbits[c+cbit_word];
697     try_next = FALSE;
698     break;
699    
700     case OP_WORDCHAR:
701     for (c = 0; c < 32; c++)
702     start_bits[c] |= cd->cbits[c+cbit_word];
703     try_next = FALSE;
704     break;
705    
706     /* One or more character type fudges the pointer and restarts, knowing
707     it will hit a single character type and stop there. */
708    
709     case OP_TYPEPLUS:
710     case OP_TYPEMINPLUS:
711     tcode++;
712     break;
713    
714     case OP_TYPEEXACT:
715     tcode += 3;
716     break;
717    
718     /* Zero or more repeats of character types set the bits and then
719     try again. */
720    
721     case OP_TYPEUPTO:
722     case OP_TYPEMINUPTO:
723 nigel 93 case OP_TYPEPOSUPTO:
724 nigel 77 tcode += 2; /* Fall through */
725    
726     case OP_TYPESTAR:
727     case OP_TYPEMINSTAR:
728 nigel 93 case OP_TYPEPOSSTAR:
729 nigel 77 case OP_TYPEQUERY:
730     case OP_TYPEMINQUERY:
731 nigel 93 case OP_TYPEPOSQUERY:
732 nigel 77 switch(tcode[1])
733     {
734     case OP_ANY:
735 ph10 345 case OP_ALLANY:
736 nigel 93 return SSB_FAIL;
737 nigel 77
738     case OP_NOT_DIGIT:
739     for (c = 0; c < 32; c++)
740     start_bits[c] |= ~cd->cbits[c+cbit_digit];
741     break;
742    
743     case OP_DIGIT:
744     for (c = 0; c < 32; c++)
745     start_bits[c] |= cd->cbits[c+cbit_digit];
746     break;
747    
748 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
749     discard it. */
750    
751 nigel 77 case OP_NOT_WHITESPACE:
752     for (c = 0; c < 32; c++)
753 nigel 91 {
754     int d = cd->cbits[c+cbit_space];
755     if (c == 1) d &= ~0x08;
756     start_bits[c] |= ~d;
757     }
758 nigel 77 break;
759    
760 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
761     discard it. */
762    
763 nigel 77 case OP_WHITESPACE:
764     for (c = 0; c < 32; c++)
765 nigel 91 {
766     int d = cd->cbits[c+cbit_space];
767     if (c == 1) d &= ~0x08;
768     start_bits[c] |= d;
769     }
770 nigel 77 break;
771    
772     case OP_NOT_WORDCHAR:
773     for (c = 0; c < 32; c++)
774     start_bits[c] |= ~cd->cbits[c+cbit_word];
775     break;
776    
777     case OP_WORDCHAR:
778     for (c = 0; c < 32; c++)
779     start_bits[c] |= cd->cbits[c+cbit_word];
780     break;
781     }
782    
783     tcode += 2;
784     break;
785    
786     /* Character class where all the information is in a bit map: set the
787     bits and either carry on or not, according to the repeat count. If it was
788     a negative class, and we are operating with UTF-8 characters, any byte
789     with a value >= 0xc4 is a potentially valid starter because it starts a
790     character with a value > 255. */
791    
792     case OP_NCLASS:
793 ph10 111 #ifdef SUPPORT_UTF8
794 nigel 77 if (utf8)
795     {
796     start_bits[24] |= 0xf0; /* Bits for 0xc4 - 0xc8 */
797     memset(start_bits+25, 0xff, 7); /* Bits for 0xc9 - 0xff */
798     }
799 ph10 111 #endif
800 nigel 77 /* Fall through */
801    
802     case OP_CLASS:
803     {
804     tcode++;
805    
806     /* In UTF-8 mode, the bits in a bit map correspond to character
807     values, not to byte values. However, the bit map we are constructing is
808     for byte values. So we have to do a conversion for characters whose
809     value is > 127. In fact, there are only two possible starting bytes for
810     characters in the range 128 - 255. */
811    
812 ph10 107 #ifdef SUPPORT_UTF8
813 nigel 77 if (utf8)
814     {
815     for (c = 0; c < 16; c++) start_bits[c] |= tcode[c];
816     for (c = 128; c < 256; c++)
817     {
818     if ((tcode[c/8] && (1 << (c&7))) != 0)
819     {
820     int d = (c >> 6) | 0xc0; /* Set bit for this starter */
821     start_bits[d/8] |= (1 << (d&7)); /* and then skip on to the */
822     c = (c & 0xc0) + 0x40 - 1; /* next relevant character. */
823     }
824     }
825     }
826    
827     /* In non-UTF-8 mode, the two bit maps are completely compatible. */
828    
829     else
830 ph10 111 #endif
831 nigel 77 {
832     for (c = 0; c < 32; c++) start_bits[c] |= tcode[c];
833     }
834    
835     /* Advance past the bit map, and act on what follows */
836    
837     tcode += 32;
838     switch (*tcode)
839     {
840     case OP_CRSTAR:
841     case OP_CRMINSTAR:
842     case OP_CRQUERY:
843     case OP_CRMINQUERY:
844     tcode++;
845     break;
846    
847     case OP_CRRANGE:
848     case OP_CRMINRANGE:
849     if (((tcode[1] << 8) + tcode[2]) == 0) tcode += 5;
850     else try_next = FALSE;
851     break;
852    
853     default:
854     try_next = FALSE;
855     break;
856     }
857     }
858     break; /* End of bitmap class handling */
859    
860     } /* End of switch */
861     } /* End of try_next loop */
862    
863     code += GET(code, 1); /* Advance to next branch */
864     }
865     while (*code == OP_ALT);
866 nigel 93 return yield;
867 nigel 77 }
868    
869    
870    
871     /*************************************************
872     * Study a compiled expression *
873     *************************************************/
874    
875     /* This function is handed a compiled expression that it must study to produce
876     information that will speed up the matching. It returns a pcre_extra block
877     which then gets handed back to pcre_exec().
878    
879     Arguments:
880     re points to the compiled expression
881     options contains option bits
882     errorptr points to where to place error messages;
883     set NULL unless error
884    
885     Returns: pointer to a pcre_extra block, with study_data filled in and the
886 ph10 455 appropriate flags set;
887 nigel 77 NULL on error or if no optimization possible
888     */
889    
890 ph10 359 PCRE_EXP_DEFN pcre_extra * PCRE_CALL_CONVENTION
891 nigel 77 pcre_study(const pcre *external_re, int options, const char **errorptr)
892     {
893 ph10 455 int min;
894     BOOL bits_set = FALSE;
895 nigel 77 uschar start_bits[32];
896     pcre_extra *extra;
897     pcre_study_data *study;
898     const uschar *tables;
899 nigel 91 uschar *code;
900     compile_data compile_block;
901 nigel 77 const real_pcre *re = (const real_pcre *)external_re;
902    
903     *errorptr = NULL;
904    
905     if (re == NULL || re->magic_number != MAGIC_NUMBER)
906     {
907     *errorptr = "argument is not a compiled regular expression";
908     return NULL;
909     }
910    
911     if ((options & ~PUBLIC_STUDY_OPTIONS) != 0)
912     {
913     *errorptr = "unknown or incorrect option bit(s) set";
914     return NULL;
915     }
916    
917 nigel 91 code = (uschar *)re + re->name_table_offset +
918     (re->name_count * re->name_entry_size);
919    
920 nigel 77 /* For an anchored pattern, or an unanchored pattern that has a first char, or
921 ph10 461 a multiline pattern that matches only at "line starts", there is no point in
922 ph10 455 seeking a list of starting bytes. */
923 nigel 77
924 ph10 455 if ((re->options & PCRE_ANCHORED) == 0 &&
925     (re->flags & (PCRE_FIRSTSET|PCRE_STARTLINE)) == 0)
926     {
927     /* Set the character tables in the block that is passed around */
928 ph10 461
929 ph10 455 tables = re->tables;
930     if (tables == NULL)
931     (void)pcre_fullinfo(external_re, NULL, PCRE_INFO_DEFAULT_TABLES,
932     (void *)(&tables));
933 ph10 461
934 ph10 455 compile_block.lcc = tables + lcc_offset;
935     compile_block.fcc = tables + fcc_offset;
936     compile_block.cbits = tables + cbits_offset;
937     compile_block.ctypes = tables + ctypes_offset;
938 ph10 461
939 ph10 455 /* See if we can find a fixed set of initial characters for the pattern. */
940 ph10 461
941 ph10 455 memset(start_bits, 0, 32 * sizeof(uschar));
942 ph10 461 bits_set = set_start_bits(code, start_bits,
943     (re->options & PCRE_CASELESS) != 0, (re->options & PCRE_UTF8) != 0,
944 ph10 455 &compile_block) == SSB_DONE;
945     }
946 ph10 461
947 ph10 455 /* Find the minimum length of subject string. */
948 nigel 77
949 ph10 455 min = find_minlength(code, code, re->options);
950 nigel 77
951 ph10 455 /* Return NULL if no optimization is possible. */
952 nigel 77
953 ph10 455 if (!bits_set && min < 0) return NULL;
954 nigel 77
955     /* Get a pcre_extra block and a pcre_study_data block. The study data is put in
956     the latter, which is pointed to by the former, which may also get additional
957     data set later by the calling program. At the moment, the size of
958     pcre_study_data is fixed. We nevertheless save it in a field for returning via
959     the pcre_fullinfo() function so that if it becomes variable in the future, we
960     don't have to change that code. */
961    
962     extra = (pcre_extra *)(pcre_malloc)
963     (sizeof(pcre_extra) + sizeof(pcre_study_data));
964    
965     if (extra == NULL)
966     {
967     *errorptr = "failed to get memory";
968     return NULL;
969     }
970    
971     study = (pcre_study_data *)((char *)extra + sizeof(pcre_extra));
972     extra->flags = PCRE_EXTRA_STUDY_DATA;
973     extra->study_data = study;
974    
975     study->size = sizeof(pcre_study_data);
976 ph10 455 study->flags = 0;
977 nigel 77
978 ph10 455 if (bits_set)
979     {
980     study->flags |= PCRE_STUDY_MAPPED;
981     memcpy(study->start_bits, start_bits, sizeof(start_bits));
982     }
983 ph10 461
984 ph10 455 if (min >= 0)
985     {
986     study->flags |= PCRE_STUDY_MINLEN;
987     study->minlength = min;
988 ph10 461 }
989 ph10 455
990 nigel 77 return extra;
991     }
992    
993     /* End of pcre_study.c */

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