/[pcre]/code/trunk/pcre_study.c
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Revision 605 - (hide annotations) (download)
Fri Jun 3 18:18:30 2011 UTC (3 years, 5 months ago) by ph10
File MIME type: text/plain
File size: 36668 byte(s)
Make pcre_study() more robust against update omissions; fix ONCE oversight.

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

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