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Revision 611 - (hide annotations) (download)
Wed Jun 29 08:49:21 2011 UTC (3 years, 1 month ago) by ph10
Original Path: code/trunk/pcre_study.c
File MIME type: text/plain
File size: 36708 byte(s)
Fix \R problem with study: incorrect minimum subject length.

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 ph10 605 enum { SSB_FAIL, SSB_DONE, SSB_CONTINUE, SSB_UNKNOWN };
56 nigel 93
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 605 -3 internal error (opcode not listed)
77 ph10 455 */
78    
79     static int
80     find_minlength(const uschar *code, const uschar *startcode, int options)
81     {
82     int length = -1;
83     BOOL utf8 = (options & PCRE_UTF8) != 0;
84     BOOL had_recurse = FALSE;
85     register int branchlength = 0;
86     register uschar *cc = (uschar *)code + 1 + LINK_SIZE;
87    
88 ph10 604 if (*code == OP_CBRA || *code == OP_SCBRA ||
89     *code == OP_CBRAPOS || *code == OP_SCBRAPOS) cc += 2;
90 ph10 455
91     /* Scan along the opcodes for this branch. If we get to the end of the
92     branch, check the length against that of the other branches. */
93    
94     for (;;)
95     {
96     int d, min;
97 ph10 461 uschar *cs, *ce;
98 ph10 455 register int op = *cc;
99 ph10 461
100 ph10 455 switch (op)
101     {
102 ph10 471 case OP_COND:
103     case OP_SCOND:
104    
105     /* If there is only one branch in a condition, the implied branch has zero
106     length, so we don't add anything. This covers the DEFINE "condition"
107     automatically. */
108    
109     cs = cc + GET(cc, 1);
110     if (*cs != OP_ALT)
111     {
112     cc = cs + 1 + LINK_SIZE;
113     break;
114     }
115    
116     /* Otherwise we can fall through and treat it the same as any other
117     subpattern. */
118    
119 ph10 455 case OP_CBRA:
120 ph10 461 case OP_SCBRA:
121 ph10 455 case OP_BRA:
122 ph10 461 case OP_SBRA:
123 ph10 604 case OP_CBRAPOS:
124     case OP_SCBRAPOS:
125     case OP_BRAPOS:
126     case OP_SBRAPOS:
127 ph10 455 case OP_ONCE:
128     d = find_minlength(cc, startcode, options);
129     if (d < 0) return d;
130     branchlength += d;
131     do cc += GET(cc, 1); while (*cc == OP_ALT);
132     cc += 1 + LINK_SIZE;
133     break;
134    
135     /* Reached end of a branch; if it's a ket it is the end of a nested
136     call. If it's ALT it is an alternation in a nested call. If it is
137     END it's the end of the outer call. All can be handled by the same code. */
138    
139     case OP_ALT:
140     case OP_KET:
141     case OP_KETRMAX:
142     case OP_KETRMIN:
143 ph10 605 case OP_KETRPOS:
144 ph10 455 case OP_END:
145 ph10 461 if (length < 0 || (!had_recurse && branchlength < length))
146 ph10 455 length = branchlength;
147     if (*cc != OP_ALT) return length;
148     cc += 1 + LINK_SIZE;
149     branchlength = 0;
150 ph10 461 had_recurse = FALSE;
151 ph10 455 break;
152    
153     /* Skip over assertive subpatterns */
154    
155     case OP_ASSERT:
156     case OP_ASSERT_NOT:
157     case OP_ASSERTBACK:
158     case OP_ASSERTBACK_NOT:
159     do cc += GET(cc, 1); while (*cc == OP_ALT);
160     /* Fall through */
161    
162     /* Skip over things that don't match chars */
163    
164     case OP_REVERSE:
165     case OP_CREF:
166 ph10 459 case OP_NCREF:
167 ph10 455 case OP_RREF:
168 ph10 459 case OP_NRREF:
169 ph10 455 case OP_DEF:
170     case OP_CALLOUT:
171     case OP_SOD:
172     case OP_SOM:
173     case OP_EOD:
174     case OP_EODN:
175     case OP_CIRC:
176 ph10 602 case OP_CIRCM:
177 ph10 455 case OP_DOLL:
178 ph10 602 case OP_DOLLM:
179 ph10 455 case OP_NOT_WORD_BOUNDARY:
180     case OP_WORD_BOUNDARY:
181     cc += _pcre_OP_lengths[*cc];
182     break;
183 ph10 461
184 ph10 455 /* Skip over a subpattern that has a {0} or {0,x} quantifier */
185    
186     case OP_BRAZERO:
187 ph10 461 case OP_BRAMINZERO:
188 ph10 604 case OP_BRAPOSZERO:
189 ph10 455 case OP_SKIPZERO:
190     cc += _pcre_OP_lengths[*cc];
191     do cc += GET(cc, 1); while (*cc == OP_ALT);
192     cc += 1 + LINK_SIZE;
193     break;
194    
195     /* Handle literal characters and + repetitions */
196    
197     case OP_CHAR:
198 ph10 602 case OP_CHARI:
199 ph10 455 case OP_NOT:
200 ph10 602 case OP_NOTI:
201 ph10 455 case OP_PLUS:
202 ph10 603 case OP_PLUSI:
203 ph10 455 case OP_MINPLUS:
204 ph10 603 case OP_MINPLUSI:
205 ph10 455 case OP_POSPLUS:
206 ph10 603 case OP_POSPLUSI:
207 ph10 455 case OP_NOTPLUS:
208 ph10 603 case OP_NOTPLUSI:
209 ph10 455 case OP_NOTMINPLUS:
210 ph10 603 case OP_NOTMINPLUSI:
211 ph10 455 case OP_NOTPOSPLUS:
212 ph10 603 case OP_NOTPOSPLUSI:
213 ph10 455 branchlength++;
214     cc += 2;
215     #ifdef SUPPORT_UTF8
216     if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
217     #endif
218     break;
219 ph10 461
220 ph10 455 case OP_TYPEPLUS:
221     case OP_TYPEMINPLUS:
222 ph10 461 case OP_TYPEPOSPLUS:
223 ph10 455 branchlength++;
224     cc += (cc[1] == OP_PROP || cc[1] == OP_NOTPROP)? 4 : 2;
225     break;
226    
227     /* Handle exact repetitions. The count is already in characters, but we
228     need to skip over a multibyte character in UTF8 mode. */
229    
230     case OP_EXACT:
231 ph10 603 case OP_EXACTI:
232 ph10 461 case OP_NOTEXACT:
233 ph10 603 case OP_NOTEXACTI:
234 ph10 455 branchlength += GET2(cc,1);
235     cc += 4;
236     #ifdef SUPPORT_UTF8
237     if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
238     #endif
239     break;
240    
241     case OP_TYPEEXACT:
242     branchlength += GET2(cc,1);
243     cc += (cc[3] == OP_PROP || cc[3] == OP_NOTPROP)? 6 : 4;
244     break;
245    
246     /* Handle single-char non-literal matchers */
247    
248     case OP_PROP:
249     case OP_NOTPROP:
250     cc += 2;
251     /* Fall through */
252    
253     case OP_NOT_DIGIT:
254     case OP_DIGIT:
255     case OP_NOT_WHITESPACE:
256     case OP_WHITESPACE:
257     case OP_NOT_WORDCHAR:
258     case OP_WORDCHAR:
259     case OP_ANY:
260     case OP_ALLANY:
261     case OP_EXTUNI:
262 ph10 461 case OP_HSPACE:
263 ph10 455 case OP_NOT_HSPACE:
264     case OP_VSPACE:
265 ph10 461 case OP_NOT_VSPACE:
266 ph10 455 branchlength++;
267     cc++;
268     break;
269 ph10 461
270 ph10 611 /* "Any newline" might match two characters, but it also might match just
271     one. */
272 ph10 461
273 ph10 455 case OP_ANYNL:
274 ph10 611 branchlength += 1;
275 ph10 455 cc++;
276 ph10 461 break;
277 ph10 455
278     /* The single-byte matcher means we can't proceed in UTF-8 mode */
279    
280     case OP_ANYBYTE:
281     #ifdef SUPPORT_UTF8
282     if (utf8) return -1;
283     #endif
284     branchlength++;
285     cc++;
286 ph10 461 break;
287 ph10 455
288     /* For repeated character types, we have to test for \p and \P, which have
289     an extra two bytes of parameters. */
290    
291     case OP_TYPESTAR:
292     case OP_TYPEMINSTAR:
293     case OP_TYPEQUERY:
294     case OP_TYPEMINQUERY:
295     case OP_TYPEPOSSTAR:
296     case OP_TYPEPOSQUERY:
297     if (cc[1] == OP_PROP || cc[1] == OP_NOTPROP) cc += 2;
298     cc += _pcre_OP_lengths[op];
299     break;
300    
301     case OP_TYPEUPTO:
302     case OP_TYPEMINUPTO:
303     case OP_TYPEPOSUPTO:
304     if (cc[3] == OP_PROP || cc[3] == OP_NOTPROP) cc += 2;
305     cc += _pcre_OP_lengths[op];
306     break;
307    
308     /* Check a class for variable quantification */
309    
310     #ifdef SUPPORT_UTF8
311     case OP_XCLASS:
312     cc += GET(cc, 1) - 33;
313     /* Fall through */
314     #endif
315    
316     case OP_CLASS:
317     case OP_NCLASS:
318     cc += 33;
319    
320     switch (*cc)
321     {
322     case OP_CRPLUS:
323     case OP_CRMINPLUS:
324     branchlength++;
325 ph10 461 /* Fall through */
326 ph10 455
327     case OP_CRSTAR:
328     case OP_CRMINSTAR:
329     case OP_CRQUERY:
330     case OP_CRMINQUERY:
331 ph10 461 cc++;
332 ph10 455 break;
333 ph10 461
334 ph10 455 case OP_CRRANGE:
335     case OP_CRMINRANGE:
336     branchlength += GET2(cc,1);
337     cc += 5;
338     break;
339 ph10 461
340 ph10 455 default:
341     branchlength++;
342 ph10 461 break;
343 ph10 455 }
344     break;
345 ph10 461
346     /* Backreferences and subroutine calls are treated in the same way: we find
347     the minimum length for the subpattern. A recursion, however, causes an
348 ph10 455 a flag to be set that causes the length of this branch to be ignored. The
349     logic is that a recursion can only make sense if there is another
350     alternation that stops the recursing. That will provide the minimum length
351     (when no recursion happens). A backreference within the group that it is
352 ph10 469 referencing behaves in the same way.
353    
354 ph10 467 If PCRE_JAVASCRIPT_COMPAT is set, a backreference to an unset bracket
355     matches an empty string (by default it causes a matching failure), so in
356     that case we must set the minimum length to zero. */
357 ph10 461
358 ph10 455 case OP_REF:
359 ph10 602 case OP_REFI:
360 ph10 467 if ((options & PCRE_JAVASCRIPT_COMPAT) == 0)
361 ph10 469 {
362 ph10 467 ce = cs = (uschar *)_pcre_find_bracket(startcode, utf8, GET2(cc, 1));
363     if (cs == NULL) return -2;
364     do ce += GET(ce, 1); while (*ce == OP_ALT);
365     if (cc > cs && cc < ce)
366     {
367     d = 0;
368     had_recurse = TRUE;
369     }
370     else d = find_minlength(cs, startcode, options);
371 ph10 461 }
372 ph10 469 else d = 0;
373 ph10 461 cc += 3;
374 ph10 455
375     /* Handle repeated back references */
376 ph10 461
377 ph10 455 switch (*cc)
378     {
379     case OP_CRSTAR:
380     case OP_CRMINSTAR:
381     case OP_CRQUERY:
382     case OP_CRMINQUERY:
383     min = 0;
384     cc++;
385     break;
386 ph10 605
387     case OP_CRPLUS:
388     case OP_CRMINPLUS:
389     min = 1;
390     cc++;
391     break;
392    
393 ph10 455 case OP_CRRANGE:
394     case OP_CRMINRANGE:
395     min = GET2(cc, 1);
396     cc += 5;
397     break;
398 ph10 461
399 ph10 455 default:
400     min = 1;
401     break;
402     }
403    
404     branchlength += min * d;
405 ph10 461 break;
406 ph10 455
407 ph10 461 case OP_RECURSE:
408 ph10 455 cs = ce = (uschar *)startcode + GET(cc, 1);
409     if (cs == NULL) return -2;
410     do ce += GET(ce, 1); while (*ce == OP_ALT);
411     if (cc > cs && cc < ce)
412 ph10 461 had_recurse = TRUE;
413     else
414 ph10 455 branchlength += find_minlength(cs, startcode, options);
415     cc += 1 + LINK_SIZE;
416     break;
417    
418     /* Anything else does not or need not match a character. We can get the
419 ph10 461 item's length from the table, but for those that can match zero occurrences
420 ph10 602 of a character, we must take special action for UTF-8 characters. As it
421     happens, the "NOT" versions of these opcodes are used at present only for
422     ASCII characters, so they could be omitted from this list. However, in
423 ph10 605 future that may change, so we include them here so as not to leave a
424 ph10 603 gotcha for a future maintainer. */
425 ph10 461
426 ph10 455 case OP_UPTO:
427 ph10 602 case OP_UPTOI:
428 ph10 461 case OP_NOTUPTO:
429 ph10 602 case OP_NOTUPTOI:
430 ph10 455 case OP_MINUPTO:
431 ph10 602 case OP_MINUPTOI:
432 ph10 461 case OP_NOTMINUPTO:
433 ph10 602 case OP_NOTMINUPTOI:
434 ph10 455 case OP_POSUPTO:
435 ph10 602 case OP_POSUPTOI:
436     case OP_NOTPOSUPTO:
437     case OP_NOTPOSUPTOI:
438    
439 ph10 455 case OP_STAR:
440 ph10 602 case OP_STARI:
441     case OP_NOTSTAR:
442     case OP_NOTSTARI:
443 ph10 455 case OP_MINSTAR:
444 ph10 602 case OP_MINSTARI:
445 ph10 461 case OP_NOTMINSTAR:
446 ph10 602 case OP_NOTMINSTARI:
447 ph10 455 case OP_POSSTAR:
448 ph10 602 case OP_POSSTARI:
449 ph10 461 case OP_NOTPOSSTAR:
450 ph10 602 case OP_NOTPOSSTARI:
451    
452 ph10 455 case OP_QUERY:
453 ph10 602 case OP_QUERYI:
454     case OP_NOTQUERY:
455     case OP_NOTQUERYI:
456 ph10 455 case OP_MINQUERY:
457 ph10 602 case OP_MINQUERYI:
458 ph10 455 case OP_NOTMINQUERY:
459 ph10 602 case OP_NOTMINQUERYI:
460 ph10 455 case OP_POSQUERY:
461 ph10 602 case OP_POSQUERYI:
462 ph10 461 case OP_NOTPOSQUERY:
463 ph10 602 case OP_NOTPOSQUERYI:
464    
465 ph10 455 cc += _pcre_OP_lengths[op];
466 ph10 461 #ifdef SUPPORT_UTF8
467 ph10 455 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
468 ph10 461 #endif
469 ph10 455 break;
470 ph10 512
471 ph10 510 /* Skip these, but we need to add in the name length. */
472 ph10 512
473 ph10 510 case OP_MARK:
474     case OP_PRUNE_ARG:
475     case OP_SKIP_ARG:
476     cc += _pcre_OP_lengths[op] + cc[1];
477 ph10 512 break;
478 ph10 455
479 ph10 550 case OP_THEN_ARG:
480     cc += _pcre_OP_lengths[op] + cc[1+LINK_SIZE];
481     break;
482    
483 ph10 603 /* The remaining opcodes are just skipped over. */
484 ph10 461
485 ph10 603 case OP_ACCEPT:
486     case OP_CLOSE:
487     case OP_COMMIT:
488     case OP_FAIL:
489     case OP_PRUNE:
490     case OP_SET_SOM:
491     case OP_SKIP:
492 ph10 605 case OP_THEN:
493 ph10 455 cc += _pcre_OP_lengths[op];
494     break;
495 ph10 605
496 ph10 603 /* This should not occur: we list all opcodes explicitly so that when
497     new ones get added they are properly considered. */
498    
499     default:
500     return -3;
501 ph10 455 }
502     }
503     /* Control never gets here */
504     }
505    
506    
507    
508     /*************************************************
509 nigel 77 * Set a bit and maybe its alternate case *
510     *************************************************/
511    
512 ph10 535 /* Given a character, set its first byte's bit in the table, and also the
513 ph10 520 corresponding bit for the other version of a letter if we are caseless. In
514     UTF-8 mode, for characters greater than 127, we can only do the caseless thing
515     when Unicode property support is available.
516 nigel 77
517     Arguments:
518     start_bits points to the bit map
519 ph10 520 p points to the character
520 nigel 77 caseless the caseless flag
521     cd the block with char table pointers
522 ph10 535 utf8 TRUE for UTF-8 mode
523 nigel 77
524 ph10 520 Returns: pointer after the character
525 nigel 77 */
526    
527 ph10 520 static const uschar *
528     set_table_bit(uschar *start_bits, const uschar *p, BOOL caseless,
529     compile_data *cd, BOOL utf8)
530 nigel 77 {
531 ph10 520 unsigned int c = *p;
532    
533 ph10 524 SET_BIT(c);
534    
535 ph10 520 #ifdef SUPPORT_UTF8
536     if (utf8 && c > 127)
537     {
538     GETCHARINC(c, p);
539     #ifdef SUPPORT_UCP
540     if (caseless)
541     {
542 ph10 535 uschar buff[8];
543 ph10 520 c = UCD_OTHERCASE(c);
544 ph10 535 (void)_pcre_ord2utf8(c, buff);
545     SET_BIT(buff[0]);
546     }
547     #endif
548 ph10 520 return p;
549     }
550 ph10 535 #endif
551 ph10 520
552     /* Not UTF-8 mode, or character is less than 127. */
553    
554 ph10 524 if (caseless && (cd->ctypes[c] & ctype_letter) != 0) SET_BIT(cd->fcc[c]);
555 ph10 520 return p + 1;
556 nigel 77 }
557    
558    
559    
560     /*************************************************
561 ph10 539 * Set bits for a positive character type *
562     *************************************************/
563    
564     /* This function sets starting bits for a character type. In UTF-8 mode, we can
565     only do a direct setting for bytes less than 128, as otherwise there can be
566     confusion with bytes in the middle of UTF-8 characters. In a "traditional"
567     environment, the tables will only recognize ASCII characters anyway, but in at
568     least one Windows environment, some higher bytes bits were set in the tables.
569     So we deal with that case by considering the UTF-8 encoding.
570    
571     Arguments:
572     start_bits the starting bitmap
573     cbit type the type of character wanted
574     table_limit 32 for non-UTF-8; 16 for UTF-8
575 ph10 545 cd the block with char table pointers
576 ph10 539
577     Returns: nothing
578     */
579    
580     static void
581     set_type_bits(uschar *start_bits, int cbit_type, int table_limit,
582     compile_data *cd)
583     {
584 ph10 545 register int c;
585 ph10 539 for (c = 0; c < table_limit; c++) start_bits[c] |= cd->cbits[c+cbit_type];
586     if (table_limit == 32) return;
587     for (c = 128; c < 256; c++)
588     {
589     if ((cd->cbits[c/8] & (1 << (c&7))) != 0)
590     {
591     uschar buff[8];
592     (void)_pcre_ord2utf8(c, buff);
593 ph10 545 SET_BIT(buff[0]);
594     }
595     }
596 ph10 539 }
597    
598    
599     /*************************************************
600     * Set bits for a negative character type *
601     *************************************************/
602    
603     /* This function sets starting bits for a negative character type such as \D.
604     In UTF-8 mode, we can only do a direct setting for bytes less than 128, as
605     otherwise there can be confusion with bytes in the middle of UTF-8 characters.
606 ph10 545 Unlike in the positive case, where we can set appropriate starting bits for
607 ph10 539 specific high-valued UTF-8 characters, in this case we have to set the bits for
608 ph10 545 all high-valued characters. The lowest is 0xc2, but we overkill by starting at
609 ph10 539 0xc0 (192) for simplicity.
610    
611     Arguments:
612     start_bits the starting bitmap
613     cbit type the type of character wanted
614     table_limit 32 for non-UTF-8; 16 for UTF-8
615 ph10 545 cd the block with char table pointers
616 ph10 539
617     Returns: nothing
618     */
619    
620     static void
621     set_nottype_bits(uschar *start_bits, int cbit_type, int table_limit,
622     compile_data *cd)
623     {
624 ph10 545 register int c;
625 ph10 539 for (c = 0; c < table_limit; c++) start_bits[c] |= ~cd->cbits[c+cbit_type];
626     if (table_limit != 32) for (c = 24; c < 32; c++) start_bits[c] = 0xff;
627     }
628    
629    
630    
631     /*************************************************
632 nigel 93 * Create bitmap of starting bytes *
633 nigel 77 *************************************************/
634    
635 nigel 93 /* This function scans a compiled unanchored expression recursively and
636     attempts to build a bitmap of the set of possible starting bytes. As time goes
637     by, we may be able to get more clever at doing this. The SSB_CONTINUE return is
638     useful for parenthesized groups in patterns such as (a*)b where the group
639     provides some optional starting bytes but scanning must continue at the outer
640     level to find at least one mandatory byte. At the outermost level, this
641     function fails unless the result is SSB_DONE.
642 nigel 77
643     Arguments:
644     code points to an expression
645     start_bits points to a 32-byte table, initialized to 0
646     utf8 TRUE if in UTF-8 mode
647     cd the block with char table pointers
648    
649 nigel 93 Returns: SSB_FAIL => Failed to find any starting bytes
650     SSB_DONE => Found mandatory starting bytes
651     SSB_CONTINUE => Found optional starting bytes
652 ph10 605 SSB_UNKNOWN => Hit an unrecognized opcode
653 nigel 77 */
654    
655 nigel 93 static int
656 ph10 605 set_start_bits(const uschar *code, uschar *start_bits, BOOL utf8,
657 ph10 603 compile_data *cd)
658 nigel 77 {
659     register int c;
660 nigel 93 int yield = SSB_DONE;
661 ph10 538 int table_limit = utf8? 16:32;
662 nigel 77
663 nigel 91 #if 0
664     /* ========================================================================= */
665     /* The following comment and code was inserted in January 1999. In May 2006,
666     when it was observed to cause compiler warnings about unused values, I took it
667     out again. If anybody is still using OS/2, they will have to put it back
668     manually. */
669    
670 nigel 77 /* This next statement and the later reference to dummy are here in order to
671     trick the optimizer of the IBM C compiler for OS/2 into generating correct
672     code. Apparently IBM isn't going to fix the problem, and we would rather not
673     disable optimization (in this module it actually makes a big difference, and
674     the pcre module can use all the optimization it can get). */
675    
676     volatile int dummy;
677 nigel 91 /* ========================================================================= */
678     #endif
679 nigel 77
680     do
681     {
682     BOOL try_next = TRUE;
683 ph10 604 const uschar *tcode = code + 1 + LINK_SIZE;
684 ph10 605
685 ph10 604 if (*code == OP_CBRA || *code == OP_SCBRA ||
686     *code == OP_CBRAPOS || *code == OP_SCBRAPOS) tcode += 2;
687 nigel 77
688 nigel 93 while (try_next) /* Loop for items in this branch */
689 nigel 77 {
690 nigel 93 int rc;
691     switch(*tcode)
692 nigel 77 {
693 ph10 605 /* If we reach something we don't understand, it means a new opcode has
694     been created that hasn't been added to this code. Hopefully this problem
695     will be discovered during testing. */
696 nigel 77
697     default:
698 ph10 605 return SSB_UNKNOWN;
699    
700     /* Fail for a valid opcode that implies no starting bits. */
701    
702     case OP_ACCEPT:
703     case OP_ALLANY:
704     case OP_ANY:
705     case OP_ANYBYTE:
706     case OP_CIRC:
707     case OP_CIRCM:
708     case OP_CLOSE:
709     case OP_COMMIT:
710     case OP_COND:
711     case OP_CREF:
712     case OP_DEF:
713     case OP_DOLL:
714     case OP_DOLLM:
715     case OP_END:
716     case OP_EOD:
717     case OP_EODN:
718     case OP_EXTUNI:
719     case OP_FAIL:
720     case OP_MARK:
721     case OP_NCREF:
722     case OP_NOT:
723     case OP_NOTEXACT:
724     case OP_NOTEXACTI:
725     case OP_NOTI:
726     case OP_NOTMINPLUS:
727     case OP_NOTMINPLUSI:
728     case OP_NOTMINQUERY:
729     case OP_NOTMINQUERYI:
730     case OP_NOTMINSTAR:
731     case OP_NOTMINSTARI:
732     case OP_NOTMINUPTO:
733     case OP_NOTMINUPTOI:
734     case OP_NOTPLUS:
735     case OP_NOTPLUSI:
736     case OP_NOTPOSPLUS:
737     case OP_NOTPOSPLUSI:
738     case OP_NOTPOSQUERY:
739     case OP_NOTPOSQUERYI:
740     case OP_NOTPOSSTAR:
741     case OP_NOTPOSSTARI:
742     case OP_NOTPOSUPTO:
743     case OP_NOTPOSUPTOI:
744     case OP_NOTPROP:
745     case OP_NOTQUERY:
746     case OP_NOTQUERYI:
747     case OP_NOTSTAR:
748     case OP_NOTSTARI:
749     case OP_NOTUPTO:
750     case OP_NOTUPTOI:
751     case OP_NOT_HSPACE:
752     case OP_NOT_VSPACE:
753     case OP_NOT_WORD_BOUNDARY:
754     case OP_NRREF:
755     case OP_PROP:
756     case OP_PRUNE:
757     case OP_PRUNE_ARG:
758     case OP_RECURSE:
759     case OP_REF:
760     case OP_REFI:
761     case OP_REVERSE:
762     case OP_RREF:
763     case OP_SCOND:
764     case OP_SET_SOM:
765     case OP_SKIP:
766     case OP_SKIP_ARG:
767     case OP_SOD:
768     case OP_SOM:
769     case OP_THEN:
770     case OP_THEN_ARG:
771     case OP_WORD_BOUNDARY:
772     case OP_XCLASS:
773 nigel 93 return SSB_FAIL;
774 nigel 77
775 nigel 93 /* If we hit a bracket or a positive lookahead assertion, recurse to set
776     bits from within the subpattern. If it can't find anything, we have to
777     give up. If it finds some mandatory character(s), we are done for this
778     branch. Otherwise, carry on scanning after the subpattern. */
779    
780     case OP_BRA:
781     case OP_SBRA:
782     case OP_CBRA:
783     case OP_SCBRA:
784 ph10 604 case OP_BRAPOS:
785     case OP_SBRAPOS:
786     case OP_CBRAPOS:
787     case OP_SCBRAPOS:
788 nigel 93 case OP_ONCE:
789     case OP_ASSERT:
790 ph10 603 rc = set_start_bits(tcode, start_bits, utf8, cd);
791 ph10 605 if (rc == SSB_FAIL || rc == SSB_UNKNOWN) return rc;
792 nigel 93 if (rc == SSB_DONE) try_next = FALSE; else
793     {
794     do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
795     tcode += 1 + LINK_SIZE;
796     }
797     break;
798    
799     /* If we hit ALT or KET, it means we haven't found anything mandatory in
800     this branch, though we might have found something optional. For ALT, we
801     continue with the next alternative, but we have to arrange that the final
802     result from subpattern is SSB_CONTINUE rather than SSB_DONE. For KET,
803     return SSB_CONTINUE: if this is the top level, that indicates failure,
804     but after a nested subpattern, it causes scanning to continue. */
805    
806     case OP_ALT:
807     yield = SSB_CONTINUE;
808     try_next = FALSE;
809     break;
810    
811     case OP_KET:
812     case OP_KETRMAX:
813     case OP_KETRMIN:
814 ph10 605 case OP_KETRPOS:
815 nigel 93 return SSB_CONTINUE;
816    
817 nigel 77 /* Skip over callout */
818    
819     case OP_CALLOUT:
820     tcode += 2 + 2*LINK_SIZE;
821     break;
822    
823     /* Skip over lookbehind and negative lookahead assertions */
824    
825     case OP_ASSERT_NOT:
826     case OP_ASSERTBACK:
827     case OP_ASSERTBACK_NOT:
828     do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
829 nigel 93 tcode += 1 + LINK_SIZE;
830 nigel 77 break;
831    
832     /* BRAZERO does the bracket, but carries on. */
833    
834     case OP_BRAZERO:
835     case OP_BRAMINZERO:
836 ph10 604 case OP_BRAPOSZERO:
837 ph10 605 rc = set_start_bits(++tcode, start_bits, utf8, cd);
838     if (rc == SSB_FAIL || rc == SSB_UNKNOWN) return rc;
839 nigel 91 /* =========================================================================
840     See the comment at the head of this function concerning the next line,
841     which was an old fudge for the benefit of OS/2.
842 nigel 77 dummy = 1;
843 nigel 91 ========================================================================= */
844 nigel 77 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
845 nigel 93 tcode += 1 + LINK_SIZE;
846 nigel 77 break;
847    
848 ph10 335 /* SKIPZERO skips the bracket. */
849    
850     case OP_SKIPZERO:
851 ph10 358 tcode++;
852 ph10 335 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
853     tcode += 1 + LINK_SIZE;
854     break;
855    
856 nigel 77 /* Single-char * or ? sets the bit and tries the next item */
857    
858     case OP_STAR:
859     case OP_MINSTAR:
860 nigel 93 case OP_POSSTAR:
861 nigel 77 case OP_QUERY:
862     case OP_MINQUERY:
863 nigel 93 case OP_POSQUERY:
864 ph10 603 tcode = set_table_bit(start_bits, tcode + 1, FALSE, cd, utf8);
865 nigel 77 break;
866    
867 ph10 602 case OP_STARI:
868     case OP_MINSTARI:
869     case OP_POSSTARI:
870     case OP_QUERYI:
871     case OP_MINQUERYI:
872     case OP_POSQUERYI:
873     tcode = set_table_bit(start_bits, tcode + 1, TRUE, cd, utf8);
874     break;
875    
876 nigel 77 /* Single-char upto sets the bit and tries the next */
877    
878     case OP_UPTO:
879     case OP_MINUPTO:
880 nigel 93 case OP_POSUPTO:
881 ph10 603 tcode = set_table_bit(start_bits, tcode + 3, FALSE, cd, utf8);
882 nigel 77 break;
883    
884 ph10 602 case OP_UPTOI:
885     case OP_MINUPTOI:
886     case OP_POSUPTOI:
887     tcode = set_table_bit(start_bits, tcode + 3, TRUE, cd, utf8);
888     break;
889    
890 nigel 77 /* At least one single char sets the bit and stops */
891    
892 ph10 602 case OP_EXACT:
893 nigel 77 tcode += 2;
894 ph10 602 /* Fall through */
895 nigel 77 case OP_CHAR:
896     case OP_PLUS:
897     case OP_MINPLUS:
898 nigel 93 case OP_POSPLUS:
899 ph10 603 (void)set_table_bit(start_bits, tcode + 1, FALSE, cd, utf8);
900 nigel 77 try_next = FALSE;
901     break;
902 ph10 535
903 ph10 603 case OP_EXACTI:
904     tcode += 2;
905     /* Fall through */
906 ph10 602 case OP_CHARI:
907     case OP_PLUSI:
908     case OP_MINPLUSI:
909     case OP_POSPLUSI:
910     (void)set_table_bit(start_bits, tcode + 1, TRUE, cd, utf8);
911     try_next = FALSE;
912     break;
913    
914 ph10 535 /* Special spacing and line-terminating items. These recognize specific
915     lists of characters. The difference between VSPACE and ANYNL is that the
916     latter can match the two-character CRLF sequence, but that is not
917     relevant for finding the first character, so their code here is
918 ph10 524 identical. */
919 ph10 535
920 ph10 524 case OP_HSPACE:
921     SET_BIT(0x09);
922     SET_BIT(0x20);
923     if (utf8)
924 ph10 535 {
925 ph10 545 SET_BIT(0xC2); /* For U+00A0 */
926 ph10 524 SET_BIT(0xE1); /* For U+1680, U+180E */
927     SET_BIT(0xE2); /* For U+2000 - U+200A, U+202F, U+205F */
928 ph10 535 SET_BIT(0xE3); /* For U+3000 */
929 ph10 524 }
930 ph10 538 else SET_BIT(0xA0);
931 ph10 524 try_next = FALSE;
932 ph10 535 break;
933 nigel 77
934 ph10 535 case OP_ANYNL:
935 ph10 524 case OP_VSPACE:
936 ph10 535 SET_BIT(0x0A);
937     SET_BIT(0x0B);
938     SET_BIT(0x0C);
939     SET_BIT(0x0D);
940 ph10 545 if (utf8)
941     {
942     SET_BIT(0xC2); /* For U+0085 */
943 ph10 538 SET_BIT(0xE2); /* For U+2028, U+2029 */
944 ph10 545 }
945 ph10 538 else SET_BIT(0x85);
946 ph10 524 try_next = FALSE;
947 ph10 535 break;
948 ph10 524
949 ph10 535 /* Single character types set the bits and stop. Note that if PCRE_UCP
950     is set, we do not see these op codes because \d etc are converted to
951 ph10 545 properties. Therefore, these apply in the case when only characters less
952 ph10 539 than 256 are recognized to match the types. */
953 nigel 77
954     case OP_NOT_DIGIT:
955 ph10 539 set_nottype_bits(start_bits, cbit_digit, table_limit, cd);
956 nigel 77 try_next = FALSE;
957     break;
958    
959     case OP_DIGIT:
960 ph10 539 set_type_bits(start_bits, cbit_digit, table_limit, cd);
961 nigel 77 try_next = FALSE;
962     break;
963    
964 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
965 ph10 539 ensure it is set as not whitespace. */
966 nigel 91
967 nigel 77 case OP_NOT_WHITESPACE:
968 ph10 539 set_nottype_bits(start_bits, cbit_space, table_limit, cd);
969     start_bits[1] |= 0x08;
970 nigel 77 try_next = FALSE;
971     break;
972    
973 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
974 ph10 539 not set it from the table. */
975 nigel 91
976 nigel 77 case OP_WHITESPACE:
977 ph10 539 c = start_bits[1]; /* Save in case it was already set */
978     set_type_bits(start_bits, cbit_space, table_limit, cd);
979     start_bits[1] = (start_bits[1] & ~0x08) | c;
980 nigel 77 try_next = FALSE;
981     break;
982    
983     case OP_NOT_WORDCHAR:
984 ph10 539 set_nottype_bits(start_bits, cbit_word, table_limit, cd);
985 nigel 77 try_next = FALSE;
986     break;
987    
988     case OP_WORDCHAR:
989 ph10 539 set_type_bits(start_bits, cbit_word, table_limit, cd);
990 nigel 77 try_next = FALSE;
991     break;
992 ph10 545
993 nigel 77 /* One or more character type fudges the pointer and restarts, knowing
994     it will hit a single character type and stop there. */
995    
996     case OP_TYPEPLUS:
997     case OP_TYPEMINPLUS:
998 ph10 535 case OP_TYPEPOSPLUS:
999 nigel 77 tcode++;
1000     break;
1001    
1002     case OP_TYPEEXACT:
1003     tcode += 3;
1004     break;
1005    
1006     /* Zero or more repeats of character types set the bits and then
1007     try again. */
1008    
1009     case OP_TYPEUPTO:
1010     case OP_TYPEMINUPTO:
1011 nigel 93 case OP_TYPEPOSUPTO:
1012 nigel 77 tcode += 2; /* Fall through */
1013    
1014     case OP_TYPESTAR:
1015     case OP_TYPEMINSTAR:
1016 nigel 93 case OP_TYPEPOSSTAR:
1017 nigel 77 case OP_TYPEQUERY:
1018     case OP_TYPEMINQUERY:
1019 nigel 93 case OP_TYPEPOSQUERY:
1020 nigel 77 switch(tcode[1])
1021     {
1022 ph10 523 default:
1023 nigel 77 case OP_ANY:
1024 ph10 345 case OP_ALLANY:
1025 nigel 93 return SSB_FAIL;
1026 ph10 535
1027 ph10 524 case OP_HSPACE:
1028     SET_BIT(0x09);
1029     SET_BIT(0x20);
1030     if (utf8)
1031 ph10 535 {
1032 ph10 545 SET_BIT(0xC2); /* For U+00A0 */
1033 ph10 524 SET_BIT(0xE1); /* For U+1680, U+180E */
1034     SET_BIT(0xE2); /* For U+2000 - U+200A, U+202F, U+205F */
1035 ph10 535 SET_BIT(0xE3); /* For U+3000 */
1036 ph10 524 }
1037 ph10 538 else SET_BIT(0xA0);
1038 ph10 535 break;
1039    
1040     case OP_ANYNL:
1041 ph10 524 case OP_VSPACE:
1042 ph10 535 SET_BIT(0x0A);
1043     SET_BIT(0x0B);
1044     SET_BIT(0x0C);
1045     SET_BIT(0x0D);
1046 ph10 545 if (utf8)
1047 ph10 538 {
1048 ph10 545 SET_BIT(0xC2); /* For U+0085 */
1049 ph10 538 SET_BIT(0xE2); /* For U+2028, U+2029 */
1050 ph10 545 }
1051 ph10 538 else SET_BIT(0x85);
1052 ph10 535 break;
1053    
1054 nigel 77 case OP_NOT_DIGIT:
1055 ph10 539 set_nottype_bits(start_bits, cbit_digit, table_limit, cd);
1056 nigel 77 break;
1057    
1058     case OP_DIGIT:
1059 ph10 539 set_type_bits(start_bits, cbit_digit, table_limit, cd);
1060 nigel 77 break;
1061    
1062 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
1063 ph10 539 ensure it gets set as not whitespace. */
1064 nigel 91
1065 nigel 77 case OP_NOT_WHITESPACE:
1066 ph10 539 set_nottype_bits(start_bits, cbit_space, table_limit, cd);
1067 ph10 545 start_bits[1] |= 0x08;
1068 nigel 77 break;
1069    
1070 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
1071 ph10 539 avoid setting it. */
1072 nigel 91
1073 nigel 77 case OP_WHITESPACE:
1074 ph10 539 c = start_bits[1]; /* Save in case it was already set */
1075     set_type_bits(start_bits, cbit_space, table_limit, cd);
1076     start_bits[1] = (start_bits[1] & ~0x08) | c;
1077 nigel 77 break;
1078    
1079     case OP_NOT_WORDCHAR:
1080 ph10 539 set_nottype_bits(start_bits, cbit_word, table_limit, cd);
1081 nigel 77 break;
1082    
1083     case OP_WORDCHAR:
1084 ph10 539 set_type_bits(start_bits, cbit_word, table_limit, cd);
1085 nigel 77 break;
1086     }
1087    
1088     tcode += 2;
1089     break;
1090    
1091     /* Character class where all the information is in a bit map: set the
1092     bits and either carry on or not, according to the repeat count. If it was
1093     a negative class, and we are operating with UTF-8 characters, any byte
1094     with a value >= 0xc4 is a potentially valid starter because it starts a
1095     character with a value > 255. */
1096    
1097     case OP_NCLASS:
1098 ph10 111 #ifdef SUPPORT_UTF8
1099 nigel 77 if (utf8)
1100     {
1101     start_bits[24] |= 0xf0; /* Bits for 0xc4 - 0xc8 */
1102     memset(start_bits+25, 0xff, 7); /* Bits for 0xc9 - 0xff */
1103     }
1104 ph10 111 #endif
1105 nigel 77 /* Fall through */
1106    
1107     case OP_CLASS:
1108     {
1109     tcode++;
1110    
1111     /* In UTF-8 mode, the bits in a bit map correspond to character
1112     values, not to byte values. However, the bit map we are constructing is
1113     for byte values. So we have to do a conversion for characters whose
1114     value is > 127. In fact, there are only two possible starting bytes for
1115     characters in the range 128 - 255. */
1116    
1117 ph10 107 #ifdef SUPPORT_UTF8
1118 nigel 77 if (utf8)
1119     {
1120     for (c = 0; c < 16; c++) start_bits[c] |= tcode[c];
1121     for (c = 128; c < 256; c++)
1122     {
1123     if ((tcode[c/8] && (1 << (c&7))) != 0)
1124     {
1125     int d = (c >> 6) | 0xc0; /* Set bit for this starter */
1126     start_bits[d/8] |= (1 << (d&7)); /* and then skip on to the */
1127     c = (c & 0xc0) + 0x40 - 1; /* next relevant character. */
1128     }
1129     }
1130     }
1131    
1132     /* In non-UTF-8 mode, the two bit maps are completely compatible. */
1133    
1134     else
1135 ph10 111 #endif
1136 nigel 77 {
1137     for (c = 0; c < 32; c++) start_bits[c] |= tcode[c];
1138     }
1139    
1140 ph10 605 /* Advance past the bit map, and act on what follows. For a zero
1141     minimum repeat, continue; otherwise stop processing. */
1142 nigel 77
1143     tcode += 32;
1144     switch (*tcode)
1145     {
1146     case OP_CRSTAR:
1147     case OP_CRMINSTAR:
1148     case OP_CRQUERY:
1149     case OP_CRMINQUERY:
1150     tcode++;
1151     break;
1152    
1153     case OP_CRRANGE:
1154     case OP_CRMINRANGE:
1155     if (((tcode[1] << 8) + tcode[2]) == 0) tcode += 5;
1156     else try_next = FALSE;
1157     break;
1158 ph10 605
1159 nigel 77 default:
1160     try_next = FALSE;
1161     break;
1162     }
1163     }
1164     break; /* End of bitmap class handling */
1165    
1166     } /* End of switch */
1167     } /* End of try_next loop */
1168    
1169     code += GET(code, 1); /* Advance to next branch */
1170     }
1171     while (*code == OP_ALT);
1172 nigel 93 return yield;
1173 nigel 77 }
1174    
1175    
1176    
1177 ph10 605
1178    
1179 nigel 77 /*************************************************
1180     * Study a compiled expression *
1181     *************************************************/
1182    
1183     /* This function is handed a compiled expression that it must study to produce
1184     information that will speed up the matching. It returns a pcre_extra block
1185     which then gets handed back to pcre_exec().
1186    
1187     Arguments:
1188     re points to the compiled expression
1189     options contains option bits
1190     errorptr points to where to place error messages;
1191     set NULL unless error
1192    
1193     Returns: pointer to a pcre_extra block, with study_data filled in and the
1194 ph10 455 appropriate flags set;
1195 nigel 77 NULL on error or if no optimization possible
1196     */
1197    
1198 ph10 359 PCRE_EXP_DEFN pcre_extra * PCRE_CALL_CONVENTION
1199 nigel 77 pcre_study(const pcre *external_re, int options, const char **errorptr)
1200     {
1201 ph10 455 int min;
1202     BOOL bits_set = FALSE;
1203 nigel 77 uschar start_bits[32];
1204     pcre_extra *extra;
1205     pcre_study_data *study;
1206     const uschar *tables;
1207 nigel 91 uschar *code;
1208     compile_data compile_block;
1209 nigel 77 const real_pcre *re = (const real_pcre *)external_re;
1210    
1211     *errorptr = NULL;
1212    
1213     if (re == NULL || re->magic_number != MAGIC_NUMBER)
1214     {
1215     *errorptr = "argument is not a compiled regular expression";
1216     return NULL;
1217     }
1218    
1219     if ((options & ~PUBLIC_STUDY_OPTIONS) != 0)
1220     {
1221     *errorptr = "unknown or incorrect option bit(s) set";
1222     return NULL;
1223     }
1224    
1225 nigel 91 code = (uschar *)re + re->name_table_offset +
1226     (re->name_count * re->name_entry_size);
1227    
1228 nigel 77 /* For an anchored pattern, or an unanchored pattern that has a first char, or
1229 ph10 461 a multiline pattern that matches only at "line starts", there is no point in
1230 ph10 455 seeking a list of starting bytes. */
1231 nigel 77
1232 ph10 455 if ((re->options & PCRE_ANCHORED) == 0 &&
1233     (re->flags & (PCRE_FIRSTSET|PCRE_STARTLINE)) == 0)
1234     {
1235 ph10 605 int rc;
1236    
1237 ph10 455 /* Set the character tables in the block that is passed around */
1238 ph10 461
1239 ph10 455 tables = re->tables;
1240     if (tables == NULL)
1241     (void)pcre_fullinfo(external_re, NULL, PCRE_INFO_DEFAULT_TABLES,
1242     (void *)(&tables));
1243 ph10 461
1244 ph10 455 compile_block.lcc = tables + lcc_offset;
1245     compile_block.fcc = tables + fcc_offset;
1246     compile_block.cbits = tables + cbits_offset;
1247     compile_block.ctypes = tables + ctypes_offset;
1248 ph10 461
1249 ph10 455 /* See if we can find a fixed set of initial characters for the pattern. */
1250 ph10 461
1251 ph10 455 memset(start_bits, 0, 32 * sizeof(uschar));
1252 ph10 605 rc = set_start_bits(code, start_bits, (re->options & PCRE_UTF8) != 0,
1253     &compile_block);
1254     bits_set = rc == SSB_DONE;
1255     if (rc == SSB_UNKNOWN) *errorptr = "internal error: opcode not recognized";
1256 ph10 455 }
1257 ph10 461
1258 ph10 455 /* Find the minimum length of subject string. */
1259 nigel 77
1260 ph10 603 switch(min = find_minlength(code, code, re->options))
1261     {
1262     case -2: *errorptr = "internal error: missing capturing bracket"; break;
1263 ph10 605 case -3: *errorptr = "internal error: opcode not recognized"; break;
1264 ph10 603 default: break;
1265 ph10 605 }
1266 nigel 77
1267 ph10 605 /* Return NULL if there's been an error or if no optimization is possible. */
1268 nigel 77
1269 ph10 605 if (*errorptr != NULL || (!bits_set && min < 0)) return NULL;
1270 nigel 77
1271     /* Get a pcre_extra block and a pcre_study_data block. The study data is put in
1272     the latter, which is pointed to by the former, which may also get additional
1273     data set later by the calling program. At the moment, the size of
1274     pcre_study_data is fixed. We nevertheless save it in a field for returning via
1275     the pcre_fullinfo() function so that if it becomes variable in the future, we
1276     don't have to change that code. */
1277    
1278     extra = (pcre_extra *)(pcre_malloc)
1279     (sizeof(pcre_extra) + sizeof(pcre_study_data));
1280    
1281     if (extra == NULL)
1282     {
1283     *errorptr = "failed to get memory";
1284     return NULL;
1285     }
1286    
1287     study = (pcre_study_data *)((char *)extra + sizeof(pcre_extra));
1288     extra->flags = PCRE_EXTRA_STUDY_DATA;
1289     extra->study_data = study;
1290    
1291     study->size = sizeof(pcre_study_data);
1292 ph10 455 study->flags = 0;
1293 nigel 77
1294 ph10 455 if (bits_set)
1295     {
1296     study->flags |= PCRE_STUDY_MAPPED;
1297     memcpy(study->start_bits, start_bits, sizeof(start_bits));
1298     }
1299 ph10 461
1300 ph10 455 if (min >= 0)
1301     {
1302     study->flags |= PCRE_STUDY_MINLEN;
1303     study->minlength = min;
1304 ph10 461 }
1305 ph10 455
1306 nigel 77 return extra;
1307     }
1308    
1309     /* End of pcre_study.c */

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