/[pcre]/code/trunk/pcre_study.c
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Revision 620 - (hide annotations) (download)
Sun Jul 17 13:53:14 2011 UTC (3 years, 4 months ago) by ph10
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File size: 37527 byte(s)
Fix mutual recursion minimum calculation in study bug.

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 ph10 612 code pointer to start of group (the bracket)
70     startcode pointer to start of the whole pattern
71     options the compiling options
72     had_accept pointer to flag for (*ACCEPT) encountered
73 ph10 620 int RECURSE depth
74 ph10 455
75     Returns: the minimum length
76     -1 if \C was encountered
77 ph10 461 -2 internal error (missing capturing bracket)
78 ph10 605 -3 internal error (opcode not listed)
79 ph10 455 */
80    
81     static int
82 ph10 612 find_minlength(const uschar *code, const uschar *startcode, int options,
83 ph10 620 BOOL *had_accept_ptr, int recurse_depth)
84 ph10 455 {
85     int length = -1;
86     BOOL utf8 = (options & PCRE_UTF8) != 0;
87     BOOL had_recurse = FALSE;
88     register int branchlength = 0;
89     register uschar *cc = (uschar *)code + 1 + LINK_SIZE;
90    
91 ph10 604 if (*code == OP_CBRA || *code == OP_SCBRA ||
92     *code == OP_CBRAPOS || *code == OP_SCBRAPOS) cc += 2;
93 ph10 455
94     /* Scan along the opcodes for this branch. If we get to the end of the
95     branch, check the length against that of the other branches. */
96    
97     for (;;)
98     {
99     int d, min;
100 ph10 461 uschar *cs, *ce;
101 ph10 455 register int op = *cc;
102 ph10 461
103 ph10 455 switch (op)
104     {
105 ph10 471 case OP_COND:
106     case OP_SCOND:
107    
108     /* If there is only one branch in a condition, the implied branch has zero
109     length, so we don't add anything. This covers the DEFINE "condition"
110     automatically. */
111    
112     cs = cc + GET(cc, 1);
113     if (*cs != OP_ALT)
114     {
115     cc = cs + 1 + LINK_SIZE;
116     break;
117     }
118    
119     /* Otherwise we can fall through and treat it the same as any other
120     subpattern. */
121    
122 ph10 455 case OP_CBRA:
123 ph10 461 case OP_SCBRA:
124 ph10 455 case OP_BRA:
125 ph10 461 case OP_SBRA:
126 ph10 604 case OP_CBRAPOS:
127     case OP_SCBRAPOS:
128     case OP_BRAPOS:
129     case OP_SBRAPOS:
130 ph10 455 case OP_ONCE:
131 ph10 620 d = find_minlength(cc, startcode, options, had_accept_ptr, recurse_depth);
132 ph10 455 if (d < 0) return d;
133     branchlength += d;
134 ph10 612 if (*had_accept_ptr) return branchlength;
135 ph10 455 do cc += GET(cc, 1); while (*cc == OP_ALT);
136     cc += 1 + LINK_SIZE;
137     break;
138    
139     /* Reached end of a branch; if it's a ket it is the end of a nested
140 ph10 612 call. If it's ALT it is an alternation in a nested call. If it is END it's
141     the end of the outer call. All can be handled by the same code. If it is
142     ACCEPT, it is essentially the same as END, but we set a flag so that
143     counting stops. */
144 ph10 455
145 ph10 612 case OP_ACCEPT:
146 ph10 613 case OP_ASSERT_ACCEPT:
147 ph10 612 *had_accept_ptr = TRUE;
148     /* Fall through */
149 ph10 455 case OP_ALT:
150     case OP_KET:
151     case OP_KETRMAX:
152     case OP_KETRMIN:
153 ph10 605 case OP_KETRPOS:
154 ph10 455 case OP_END:
155 ph10 461 if (length < 0 || (!had_recurse && branchlength < length))
156 ph10 455 length = branchlength;
157 ph10 612 if (op != OP_ALT) return length;
158 ph10 455 cc += 1 + LINK_SIZE;
159     branchlength = 0;
160 ph10 461 had_recurse = FALSE;
161 ph10 455 break;
162    
163     /* Skip over assertive subpatterns */
164    
165     case OP_ASSERT:
166     case OP_ASSERT_NOT:
167     case OP_ASSERTBACK:
168     case OP_ASSERTBACK_NOT:
169     do cc += GET(cc, 1); while (*cc == OP_ALT);
170     /* Fall through */
171    
172     /* Skip over things that don't match chars */
173    
174     case OP_REVERSE:
175     case OP_CREF:
176 ph10 459 case OP_NCREF:
177 ph10 455 case OP_RREF:
178 ph10 459 case OP_NRREF:
179 ph10 455 case OP_DEF:
180     case OP_CALLOUT:
181     case OP_SOD:
182     case OP_SOM:
183     case OP_EOD:
184     case OP_EODN:
185     case OP_CIRC:
186 ph10 602 case OP_CIRCM:
187 ph10 455 case OP_DOLL:
188 ph10 602 case OP_DOLLM:
189 ph10 455 case OP_NOT_WORD_BOUNDARY:
190     case OP_WORD_BOUNDARY:
191     cc += _pcre_OP_lengths[*cc];
192     break;
193 ph10 461
194 ph10 455 /* Skip over a subpattern that has a {0} or {0,x} quantifier */
195    
196     case OP_BRAZERO:
197 ph10 461 case OP_BRAMINZERO:
198 ph10 604 case OP_BRAPOSZERO:
199 ph10 455 case OP_SKIPZERO:
200     cc += _pcre_OP_lengths[*cc];
201     do cc += GET(cc, 1); while (*cc == OP_ALT);
202     cc += 1 + LINK_SIZE;
203     break;
204    
205     /* Handle literal characters and + repetitions */
206    
207     case OP_CHAR:
208 ph10 602 case OP_CHARI:
209 ph10 455 case OP_NOT:
210 ph10 602 case OP_NOTI:
211 ph10 455 case OP_PLUS:
212 ph10 603 case OP_PLUSI:
213 ph10 455 case OP_MINPLUS:
214 ph10 603 case OP_MINPLUSI:
215 ph10 455 case OP_POSPLUS:
216 ph10 603 case OP_POSPLUSI:
217 ph10 455 case OP_NOTPLUS:
218 ph10 603 case OP_NOTPLUSI:
219 ph10 455 case OP_NOTMINPLUS:
220 ph10 603 case OP_NOTMINPLUSI:
221 ph10 455 case OP_NOTPOSPLUS:
222 ph10 603 case OP_NOTPOSPLUSI:
223 ph10 455 branchlength++;
224     cc += 2;
225     #ifdef SUPPORT_UTF8
226     if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
227     #endif
228     break;
229 ph10 461
230 ph10 455 case OP_TYPEPLUS:
231     case OP_TYPEMINPLUS:
232 ph10 461 case OP_TYPEPOSPLUS:
233 ph10 455 branchlength++;
234     cc += (cc[1] == OP_PROP || cc[1] == OP_NOTPROP)? 4 : 2;
235     break;
236    
237     /* Handle exact repetitions. The count is already in characters, but we
238     need to skip over a multibyte character in UTF8 mode. */
239    
240     case OP_EXACT:
241 ph10 603 case OP_EXACTI:
242 ph10 461 case OP_NOTEXACT:
243 ph10 603 case OP_NOTEXACTI:
244 ph10 455 branchlength += GET2(cc,1);
245     cc += 4;
246     #ifdef SUPPORT_UTF8
247     if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
248     #endif
249     break;
250    
251     case OP_TYPEEXACT:
252     branchlength += GET2(cc,1);
253     cc += (cc[3] == OP_PROP || cc[3] == OP_NOTPROP)? 6 : 4;
254     break;
255    
256     /* Handle single-char non-literal matchers */
257    
258     case OP_PROP:
259     case OP_NOTPROP:
260     cc += 2;
261     /* Fall through */
262    
263     case OP_NOT_DIGIT:
264     case OP_DIGIT:
265     case OP_NOT_WHITESPACE:
266     case OP_WHITESPACE:
267     case OP_NOT_WORDCHAR:
268     case OP_WORDCHAR:
269     case OP_ANY:
270     case OP_ALLANY:
271     case OP_EXTUNI:
272 ph10 461 case OP_HSPACE:
273 ph10 455 case OP_NOT_HSPACE:
274     case OP_VSPACE:
275 ph10 461 case OP_NOT_VSPACE:
276 ph10 455 branchlength++;
277     cc++;
278     break;
279 ph10 461
280 ph10 611 /* "Any newline" might match two characters, but it also might match just
281     one. */
282 ph10 461
283 ph10 455 case OP_ANYNL:
284 ph10 611 branchlength += 1;
285 ph10 455 cc++;
286 ph10 461 break;
287 ph10 455
288     /* The single-byte matcher means we can't proceed in UTF-8 mode */
289    
290     case OP_ANYBYTE:
291     #ifdef SUPPORT_UTF8
292     if (utf8) return -1;
293     #endif
294     branchlength++;
295     cc++;
296 ph10 461 break;
297 ph10 455
298     /* For repeated character types, we have to test for \p and \P, which have
299     an extra two bytes of parameters. */
300    
301     case OP_TYPESTAR:
302     case OP_TYPEMINSTAR:
303     case OP_TYPEQUERY:
304     case OP_TYPEMINQUERY:
305     case OP_TYPEPOSSTAR:
306     case OP_TYPEPOSQUERY:
307     if (cc[1] == OP_PROP || cc[1] == OP_NOTPROP) cc += 2;
308     cc += _pcre_OP_lengths[op];
309     break;
310    
311     case OP_TYPEUPTO:
312     case OP_TYPEMINUPTO:
313     case OP_TYPEPOSUPTO:
314     if (cc[3] == OP_PROP || cc[3] == OP_NOTPROP) cc += 2;
315     cc += _pcre_OP_lengths[op];
316     break;
317    
318     /* Check a class for variable quantification */
319    
320     #ifdef SUPPORT_UTF8
321     case OP_XCLASS:
322     cc += GET(cc, 1) - 33;
323     /* Fall through */
324     #endif
325    
326     case OP_CLASS:
327     case OP_NCLASS:
328     cc += 33;
329    
330     switch (*cc)
331     {
332     case OP_CRPLUS:
333     case OP_CRMINPLUS:
334     branchlength++;
335 ph10 461 /* Fall through */
336 ph10 455
337     case OP_CRSTAR:
338     case OP_CRMINSTAR:
339     case OP_CRQUERY:
340     case OP_CRMINQUERY:
341 ph10 461 cc++;
342 ph10 455 break;
343 ph10 461
344 ph10 455 case OP_CRRANGE:
345     case OP_CRMINRANGE:
346     branchlength += GET2(cc,1);
347     cc += 5;
348     break;
349 ph10 461
350 ph10 455 default:
351     branchlength++;
352 ph10 461 break;
353 ph10 455 }
354     break;
355 ph10 461
356     /* Backreferences and subroutine calls are treated in the same way: we find
357     the minimum length for the subpattern. A recursion, however, causes an
358 ph10 455 a flag to be set that causes the length of this branch to be ignored. The
359     logic is that a recursion can only make sense if there is another
360     alternation that stops the recursing. That will provide the minimum length
361     (when no recursion happens). A backreference within the group that it is
362 ph10 469 referencing behaves in the same way.
363    
364 ph10 467 If PCRE_JAVASCRIPT_COMPAT is set, a backreference to an unset bracket
365     matches an empty string (by default it causes a matching failure), so in
366     that case we must set the minimum length to zero. */
367 ph10 461
368 ph10 455 case OP_REF:
369 ph10 602 case OP_REFI:
370 ph10 467 if ((options & PCRE_JAVASCRIPT_COMPAT) == 0)
371 ph10 469 {
372 ph10 467 ce = cs = (uschar *)_pcre_find_bracket(startcode, utf8, GET2(cc, 1));
373     if (cs == NULL) return -2;
374     do ce += GET(ce, 1); while (*ce == OP_ALT);
375     if (cc > cs && cc < ce)
376     {
377     d = 0;
378     had_recurse = TRUE;
379     }
380 ph10 612 else
381     {
382 ph10 620 d = find_minlength(cs, startcode, options, had_accept_ptr,
383     recurse_depth);
384 ph10 612 *had_accept_ptr = FALSE;
385     }
386 ph10 461 }
387 ph10 469 else d = 0;
388 ph10 461 cc += 3;
389 ph10 455
390     /* Handle repeated back references */
391 ph10 461
392 ph10 455 switch (*cc)
393     {
394     case OP_CRSTAR:
395     case OP_CRMINSTAR:
396     case OP_CRQUERY:
397     case OP_CRMINQUERY:
398     min = 0;
399     cc++;
400     break;
401 ph10 605
402     case OP_CRPLUS:
403     case OP_CRMINPLUS:
404     min = 1;
405     cc++;
406     break;
407    
408 ph10 455 case OP_CRRANGE:
409     case OP_CRMINRANGE:
410     min = GET2(cc, 1);
411     cc += 5;
412     break;
413 ph10 461
414 ph10 455 default:
415     min = 1;
416     break;
417     }
418    
419     branchlength += min * d;
420 ph10 461 break;
421 ph10 620
422     /* We can easily detect direct recursion, but not mutual recursion. This is
423     caught by a recursion depth count. */
424 ph10 455
425 ph10 461 case OP_RECURSE:
426 ph10 455 cs = ce = (uschar *)startcode + GET(cc, 1);
427     if (cs == NULL) return -2;
428     do ce += GET(ce, 1); while (*ce == OP_ALT);
429 ph10 620 if ((cc > cs && cc < ce) || recurse_depth > 10)
430 ph10 461 had_recurse = TRUE;
431     else
432 ph10 612 {
433 ph10 620 branchlength += find_minlength(cs, startcode, options, had_accept_ptr,
434     recurse_depth + 1);
435 ph10 612 *had_accept_ptr = FALSE;
436     }
437 ph10 455 cc += 1 + LINK_SIZE;
438     break;
439    
440     /* Anything else does not or need not match a character. We can get the
441 ph10 461 item's length from the table, but for those that can match zero occurrences
442 ph10 602 of a character, we must take special action for UTF-8 characters. As it
443     happens, the "NOT" versions of these opcodes are used at present only for
444     ASCII characters, so they could be omitted from this list. However, in
445 ph10 605 future that may change, so we include them here so as not to leave a
446 ph10 603 gotcha for a future maintainer. */
447 ph10 461
448 ph10 455 case OP_UPTO:
449 ph10 602 case OP_UPTOI:
450 ph10 461 case OP_NOTUPTO:
451 ph10 602 case OP_NOTUPTOI:
452 ph10 455 case OP_MINUPTO:
453 ph10 602 case OP_MINUPTOI:
454 ph10 461 case OP_NOTMINUPTO:
455 ph10 602 case OP_NOTMINUPTOI:
456 ph10 455 case OP_POSUPTO:
457 ph10 602 case OP_POSUPTOI:
458     case OP_NOTPOSUPTO:
459     case OP_NOTPOSUPTOI:
460    
461 ph10 455 case OP_STAR:
462 ph10 602 case OP_STARI:
463     case OP_NOTSTAR:
464     case OP_NOTSTARI:
465 ph10 455 case OP_MINSTAR:
466 ph10 602 case OP_MINSTARI:
467 ph10 461 case OP_NOTMINSTAR:
468 ph10 602 case OP_NOTMINSTARI:
469 ph10 455 case OP_POSSTAR:
470 ph10 602 case OP_POSSTARI:
471 ph10 461 case OP_NOTPOSSTAR:
472 ph10 602 case OP_NOTPOSSTARI:
473    
474 ph10 455 case OP_QUERY:
475 ph10 602 case OP_QUERYI:
476     case OP_NOTQUERY:
477     case OP_NOTQUERYI:
478 ph10 455 case OP_MINQUERY:
479 ph10 602 case OP_MINQUERYI:
480 ph10 455 case OP_NOTMINQUERY:
481 ph10 602 case OP_NOTMINQUERYI:
482 ph10 455 case OP_POSQUERY:
483 ph10 602 case OP_POSQUERYI:
484 ph10 461 case OP_NOTPOSQUERY:
485 ph10 602 case OP_NOTPOSQUERYI:
486    
487 ph10 455 cc += _pcre_OP_lengths[op];
488 ph10 461 #ifdef SUPPORT_UTF8
489 ph10 455 if (utf8 && cc[-1] >= 0xc0) cc += _pcre_utf8_table4[cc[-1] & 0x3f];
490 ph10 461 #endif
491 ph10 455 break;
492 ph10 512
493 ph10 510 /* Skip these, but we need to add in the name length. */
494 ph10 512
495 ph10 510 case OP_MARK:
496     case OP_PRUNE_ARG:
497     case OP_SKIP_ARG:
498     cc += _pcre_OP_lengths[op] + cc[1];
499 ph10 512 break;
500 ph10 455
501 ph10 550 case OP_THEN_ARG:
502     cc += _pcre_OP_lengths[op] + cc[1+LINK_SIZE];
503     break;
504 ph10 612
505 ph10 603 /* The remaining opcodes are just skipped over. */
506 ph10 461
507 ph10 603 case OP_CLOSE:
508     case OP_COMMIT:
509     case OP_FAIL:
510     case OP_PRUNE:
511     case OP_SET_SOM:
512     case OP_SKIP:
513 ph10 605 case OP_THEN:
514 ph10 455 cc += _pcre_OP_lengths[op];
515     break;
516 ph10 605
517 ph10 603 /* This should not occur: we list all opcodes explicitly so that when
518     new ones get added they are properly considered. */
519    
520     default:
521     return -3;
522 ph10 455 }
523     }
524     /* Control never gets here */
525     }
526    
527    
528    
529     /*************************************************
530 nigel 77 * Set a bit and maybe its alternate case *
531     *************************************************/
532    
533 ph10 535 /* Given a character, set its first byte's bit in the table, and also the
534 ph10 520 corresponding bit for the other version of a letter if we are caseless. In
535     UTF-8 mode, for characters greater than 127, we can only do the caseless thing
536     when Unicode property support is available.
537 nigel 77
538     Arguments:
539     start_bits points to the bit map
540 ph10 520 p points to the character
541 nigel 77 caseless the caseless flag
542     cd the block with char table pointers
543 ph10 535 utf8 TRUE for UTF-8 mode
544 nigel 77
545 ph10 520 Returns: pointer after the character
546 nigel 77 */
547    
548 ph10 520 static const uschar *
549     set_table_bit(uschar *start_bits, const uschar *p, BOOL caseless,
550     compile_data *cd, BOOL utf8)
551 nigel 77 {
552 ph10 520 unsigned int c = *p;
553    
554 ph10 524 SET_BIT(c);
555    
556 ph10 520 #ifdef SUPPORT_UTF8
557     if (utf8 && c > 127)
558     {
559     GETCHARINC(c, p);
560     #ifdef SUPPORT_UCP
561     if (caseless)
562     {
563 ph10 535 uschar buff[8];
564 ph10 520 c = UCD_OTHERCASE(c);
565 ph10 535 (void)_pcre_ord2utf8(c, buff);
566     SET_BIT(buff[0]);
567     }
568     #endif
569 ph10 520 return p;
570     }
571 ph10 535 #endif
572 ph10 520
573     /* Not UTF-8 mode, or character is less than 127. */
574    
575 ph10 524 if (caseless && (cd->ctypes[c] & ctype_letter) != 0) SET_BIT(cd->fcc[c]);
576 ph10 520 return p + 1;
577 nigel 77 }
578    
579    
580    
581     /*************************************************
582 ph10 539 * Set bits for a positive character type *
583     *************************************************/
584    
585     /* This function sets starting bits for a character type. In UTF-8 mode, we can
586     only do a direct setting for bytes less than 128, as otherwise there can be
587     confusion with bytes in the middle of UTF-8 characters. In a "traditional"
588     environment, the tables will only recognize ASCII characters anyway, but in at
589     least one Windows environment, some higher bytes bits were set in the tables.
590     So we deal with that case by considering the UTF-8 encoding.
591    
592     Arguments:
593     start_bits the starting bitmap
594     cbit type the type of character wanted
595     table_limit 32 for non-UTF-8; 16 for UTF-8
596 ph10 545 cd the block with char table pointers
597 ph10 539
598     Returns: nothing
599     */
600    
601     static void
602     set_type_bits(uschar *start_bits, int cbit_type, int table_limit,
603     compile_data *cd)
604     {
605 ph10 545 register int c;
606 ph10 539 for (c = 0; c < table_limit; c++) start_bits[c] |= cd->cbits[c+cbit_type];
607     if (table_limit == 32) return;
608     for (c = 128; c < 256; c++)
609     {
610     if ((cd->cbits[c/8] & (1 << (c&7))) != 0)
611     {
612     uschar buff[8];
613     (void)_pcre_ord2utf8(c, buff);
614 ph10 545 SET_BIT(buff[0]);
615     }
616     }
617 ph10 539 }
618    
619    
620     /*************************************************
621     * Set bits for a negative character type *
622     *************************************************/
623    
624     /* This function sets starting bits for a negative character type such as \D.
625     In UTF-8 mode, we can only do a direct setting for bytes less than 128, as
626     otherwise there can be confusion with bytes in the middle of UTF-8 characters.
627 ph10 545 Unlike in the positive case, where we can set appropriate starting bits for
628 ph10 539 specific high-valued UTF-8 characters, in this case we have to set the bits for
629 ph10 545 all high-valued characters. The lowest is 0xc2, but we overkill by starting at
630 ph10 539 0xc0 (192) for simplicity.
631    
632     Arguments:
633     start_bits the starting bitmap
634     cbit type the type of character wanted
635     table_limit 32 for non-UTF-8; 16 for UTF-8
636 ph10 545 cd the block with char table pointers
637 ph10 539
638     Returns: nothing
639     */
640    
641     static void
642     set_nottype_bits(uschar *start_bits, int cbit_type, int table_limit,
643     compile_data *cd)
644     {
645 ph10 545 register int c;
646 ph10 539 for (c = 0; c < table_limit; c++) start_bits[c] |= ~cd->cbits[c+cbit_type];
647     if (table_limit != 32) for (c = 24; c < 32; c++) start_bits[c] = 0xff;
648     }
649    
650    
651    
652     /*************************************************
653 nigel 93 * Create bitmap of starting bytes *
654 nigel 77 *************************************************/
655    
656 nigel 93 /* This function scans a compiled unanchored expression recursively and
657     attempts to build a bitmap of the set of possible starting bytes. As time goes
658     by, we may be able to get more clever at doing this. The SSB_CONTINUE return is
659     useful for parenthesized groups in patterns such as (a*)b where the group
660     provides some optional starting bytes but scanning must continue at the outer
661     level to find at least one mandatory byte. At the outermost level, this
662     function fails unless the result is SSB_DONE.
663 nigel 77
664     Arguments:
665     code points to an expression
666     start_bits points to a 32-byte table, initialized to 0
667     utf8 TRUE if in UTF-8 mode
668     cd the block with char table pointers
669    
670 nigel 93 Returns: SSB_FAIL => Failed to find any starting bytes
671     SSB_DONE => Found mandatory starting bytes
672     SSB_CONTINUE => Found optional starting bytes
673 ph10 605 SSB_UNKNOWN => Hit an unrecognized opcode
674 nigel 77 */
675    
676 nigel 93 static int
677 ph10 605 set_start_bits(const uschar *code, uschar *start_bits, BOOL utf8,
678 ph10 603 compile_data *cd)
679 nigel 77 {
680     register int c;
681 nigel 93 int yield = SSB_DONE;
682 ph10 538 int table_limit = utf8? 16:32;
683 nigel 77
684 nigel 91 #if 0
685     /* ========================================================================= */
686     /* The following comment and code was inserted in January 1999. In May 2006,
687     when it was observed to cause compiler warnings about unused values, I took it
688     out again. If anybody is still using OS/2, they will have to put it back
689     manually. */
690    
691 nigel 77 /* This next statement and the later reference to dummy are here in order to
692     trick the optimizer of the IBM C compiler for OS/2 into generating correct
693     code. Apparently IBM isn't going to fix the problem, and we would rather not
694     disable optimization (in this module it actually makes a big difference, and
695     the pcre module can use all the optimization it can get). */
696    
697     volatile int dummy;
698 nigel 91 /* ========================================================================= */
699     #endif
700 nigel 77
701     do
702     {
703     BOOL try_next = TRUE;
704 ph10 604 const uschar *tcode = code + 1 + LINK_SIZE;
705 ph10 605
706 ph10 604 if (*code == OP_CBRA || *code == OP_SCBRA ||
707     *code == OP_CBRAPOS || *code == OP_SCBRAPOS) tcode += 2;
708 nigel 77
709 nigel 93 while (try_next) /* Loop for items in this branch */
710 nigel 77 {
711 nigel 93 int rc;
712 ph10 612
713 nigel 93 switch(*tcode)
714 nigel 77 {
715 ph10 605 /* If we reach something we don't understand, it means a new opcode has
716     been created that hasn't been added to this code. Hopefully this problem
717     will be discovered during testing. */
718 nigel 77
719     default:
720 ph10 605 return SSB_UNKNOWN;
721    
722     /* Fail for a valid opcode that implies no starting bits. */
723    
724     case OP_ACCEPT:
725 ph10 613 case OP_ASSERT_ACCEPT:
726 ph10 605 case OP_ALLANY:
727     case OP_ANY:
728     case OP_ANYBYTE:
729     case OP_CIRC:
730     case OP_CIRCM:
731     case OP_CLOSE:
732     case OP_COMMIT:
733     case OP_COND:
734     case OP_CREF:
735     case OP_DEF:
736     case OP_DOLL:
737     case OP_DOLLM:
738     case OP_END:
739     case OP_EOD:
740     case OP_EODN:
741     case OP_EXTUNI:
742     case OP_FAIL:
743     case OP_MARK:
744     case OP_NCREF:
745     case OP_NOT:
746     case OP_NOTEXACT:
747     case OP_NOTEXACTI:
748     case OP_NOTI:
749     case OP_NOTMINPLUS:
750     case OP_NOTMINPLUSI:
751     case OP_NOTMINQUERY:
752     case OP_NOTMINQUERYI:
753     case OP_NOTMINSTAR:
754     case OP_NOTMINSTARI:
755     case OP_NOTMINUPTO:
756     case OP_NOTMINUPTOI:
757     case OP_NOTPLUS:
758     case OP_NOTPLUSI:
759     case OP_NOTPOSPLUS:
760     case OP_NOTPOSPLUSI:
761     case OP_NOTPOSQUERY:
762     case OP_NOTPOSQUERYI:
763     case OP_NOTPOSSTAR:
764     case OP_NOTPOSSTARI:
765     case OP_NOTPOSUPTO:
766     case OP_NOTPOSUPTOI:
767     case OP_NOTPROP:
768     case OP_NOTQUERY:
769     case OP_NOTQUERYI:
770     case OP_NOTSTAR:
771     case OP_NOTSTARI:
772     case OP_NOTUPTO:
773     case OP_NOTUPTOI:
774     case OP_NOT_HSPACE:
775     case OP_NOT_VSPACE:
776     case OP_NOT_WORD_BOUNDARY:
777     case OP_NRREF:
778     case OP_PROP:
779     case OP_PRUNE:
780     case OP_PRUNE_ARG:
781     case OP_RECURSE:
782     case OP_REF:
783     case OP_REFI:
784     case OP_REVERSE:
785     case OP_RREF:
786     case OP_SCOND:
787     case OP_SET_SOM:
788     case OP_SKIP:
789     case OP_SKIP_ARG:
790     case OP_SOD:
791     case OP_SOM:
792     case OP_THEN:
793     case OP_THEN_ARG:
794     case OP_WORD_BOUNDARY:
795     case OP_XCLASS:
796 nigel 93 return SSB_FAIL;
797 nigel 77
798 nigel 93 /* If we hit a bracket or a positive lookahead assertion, recurse to set
799     bits from within the subpattern. If it can't find anything, we have to
800     give up. If it finds some mandatory character(s), we are done for this
801     branch. Otherwise, carry on scanning after the subpattern. */
802    
803     case OP_BRA:
804     case OP_SBRA:
805     case OP_CBRA:
806     case OP_SCBRA:
807 ph10 604 case OP_BRAPOS:
808     case OP_SBRAPOS:
809     case OP_CBRAPOS:
810     case OP_SCBRAPOS:
811 nigel 93 case OP_ONCE:
812     case OP_ASSERT:
813 ph10 603 rc = set_start_bits(tcode, start_bits, utf8, cd);
814 ph10 605 if (rc == SSB_FAIL || rc == SSB_UNKNOWN) return rc;
815 nigel 93 if (rc == SSB_DONE) try_next = FALSE; else
816     {
817     do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
818     tcode += 1 + LINK_SIZE;
819     }
820     break;
821    
822     /* If we hit ALT or KET, it means we haven't found anything mandatory in
823     this branch, though we might have found something optional. For ALT, we
824     continue with the next alternative, but we have to arrange that the final
825     result from subpattern is SSB_CONTINUE rather than SSB_DONE. For KET,
826     return SSB_CONTINUE: if this is the top level, that indicates failure,
827     but after a nested subpattern, it causes scanning to continue. */
828    
829     case OP_ALT:
830     yield = SSB_CONTINUE;
831     try_next = FALSE;
832     break;
833    
834     case OP_KET:
835     case OP_KETRMAX:
836     case OP_KETRMIN:
837 ph10 605 case OP_KETRPOS:
838 nigel 93 return SSB_CONTINUE;
839    
840 nigel 77 /* Skip over callout */
841    
842     case OP_CALLOUT:
843     tcode += 2 + 2*LINK_SIZE;
844     break;
845    
846     /* Skip over lookbehind and negative lookahead assertions */
847    
848     case OP_ASSERT_NOT:
849     case OP_ASSERTBACK:
850     case OP_ASSERTBACK_NOT:
851     do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
852 nigel 93 tcode += 1 + LINK_SIZE;
853 nigel 77 break;
854    
855     /* BRAZERO does the bracket, but carries on. */
856    
857     case OP_BRAZERO:
858     case OP_BRAMINZERO:
859 ph10 604 case OP_BRAPOSZERO:
860 ph10 605 rc = set_start_bits(++tcode, start_bits, utf8, cd);
861     if (rc == SSB_FAIL || rc == SSB_UNKNOWN) return rc;
862 nigel 91 /* =========================================================================
863     See the comment at the head of this function concerning the next line,
864     which was an old fudge for the benefit of OS/2.
865 nigel 77 dummy = 1;
866 nigel 91 ========================================================================= */
867 nigel 77 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
868 nigel 93 tcode += 1 + LINK_SIZE;
869 nigel 77 break;
870    
871 ph10 335 /* SKIPZERO skips the bracket. */
872    
873     case OP_SKIPZERO:
874 ph10 358 tcode++;
875 ph10 335 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
876     tcode += 1 + LINK_SIZE;
877     break;
878    
879 nigel 77 /* Single-char * or ? sets the bit and tries the next item */
880    
881     case OP_STAR:
882     case OP_MINSTAR:
883 nigel 93 case OP_POSSTAR:
884 nigel 77 case OP_QUERY:
885     case OP_MINQUERY:
886 nigel 93 case OP_POSQUERY:
887 ph10 603 tcode = set_table_bit(start_bits, tcode + 1, FALSE, cd, utf8);
888 nigel 77 break;
889    
890 ph10 602 case OP_STARI:
891     case OP_MINSTARI:
892     case OP_POSSTARI:
893     case OP_QUERYI:
894     case OP_MINQUERYI:
895     case OP_POSQUERYI:
896     tcode = set_table_bit(start_bits, tcode + 1, TRUE, cd, utf8);
897     break;
898    
899 nigel 77 /* Single-char upto sets the bit and tries the next */
900    
901     case OP_UPTO:
902     case OP_MINUPTO:
903 nigel 93 case OP_POSUPTO:
904 ph10 603 tcode = set_table_bit(start_bits, tcode + 3, FALSE, cd, utf8);
905 nigel 77 break;
906    
907 ph10 602 case OP_UPTOI:
908     case OP_MINUPTOI:
909     case OP_POSUPTOI:
910     tcode = set_table_bit(start_bits, tcode + 3, TRUE, cd, utf8);
911     break;
912    
913 nigel 77 /* At least one single char sets the bit and stops */
914    
915 ph10 602 case OP_EXACT:
916 nigel 77 tcode += 2;
917 ph10 602 /* Fall through */
918 nigel 77 case OP_CHAR:
919     case OP_PLUS:
920     case OP_MINPLUS:
921 nigel 93 case OP_POSPLUS:
922 ph10 603 (void)set_table_bit(start_bits, tcode + 1, FALSE, cd, utf8);
923 nigel 77 try_next = FALSE;
924     break;
925 ph10 535
926 ph10 603 case OP_EXACTI:
927     tcode += 2;
928     /* Fall through */
929 ph10 602 case OP_CHARI:
930     case OP_PLUSI:
931     case OP_MINPLUSI:
932     case OP_POSPLUSI:
933     (void)set_table_bit(start_bits, tcode + 1, TRUE, cd, utf8);
934     try_next = FALSE;
935     break;
936    
937 ph10 535 /* Special spacing and line-terminating items. These recognize specific
938     lists of characters. The difference between VSPACE and ANYNL is that the
939     latter can match the two-character CRLF sequence, but that is not
940     relevant for finding the first character, so their code here is
941 ph10 524 identical. */
942 ph10 535
943 ph10 524 case OP_HSPACE:
944     SET_BIT(0x09);
945     SET_BIT(0x20);
946     if (utf8)
947 ph10 535 {
948 ph10 545 SET_BIT(0xC2); /* For U+00A0 */
949 ph10 524 SET_BIT(0xE1); /* For U+1680, U+180E */
950     SET_BIT(0xE2); /* For U+2000 - U+200A, U+202F, U+205F */
951 ph10 535 SET_BIT(0xE3); /* For U+3000 */
952 ph10 524 }
953 ph10 538 else SET_BIT(0xA0);
954 ph10 524 try_next = FALSE;
955 ph10 535 break;
956 nigel 77
957 ph10 535 case OP_ANYNL:
958 ph10 524 case OP_VSPACE:
959 ph10 535 SET_BIT(0x0A);
960     SET_BIT(0x0B);
961     SET_BIT(0x0C);
962     SET_BIT(0x0D);
963 ph10 545 if (utf8)
964     {
965     SET_BIT(0xC2); /* For U+0085 */
966 ph10 538 SET_BIT(0xE2); /* For U+2028, U+2029 */
967 ph10 545 }
968 ph10 538 else SET_BIT(0x85);
969 ph10 524 try_next = FALSE;
970 ph10 535 break;
971 ph10 524
972 ph10 535 /* Single character types set the bits and stop. Note that if PCRE_UCP
973     is set, we do not see these op codes because \d etc are converted to
974 ph10 545 properties. Therefore, these apply in the case when only characters less
975 ph10 539 than 256 are recognized to match the types. */
976 nigel 77
977     case OP_NOT_DIGIT:
978 ph10 539 set_nottype_bits(start_bits, cbit_digit, table_limit, cd);
979 nigel 77 try_next = FALSE;
980     break;
981    
982     case OP_DIGIT:
983 ph10 539 set_type_bits(start_bits, cbit_digit, table_limit, cd);
984 nigel 77 try_next = FALSE;
985     break;
986    
987 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
988 ph10 539 ensure it is set as not whitespace. */
989 nigel 91
990 nigel 77 case OP_NOT_WHITESPACE:
991 ph10 539 set_nottype_bits(start_bits, cbit_space, table_limit, cd);
992     start_bits[1] |= 0x08;
993 nigel 77 try_next = FALSE;
994     break;
995    
996 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
997 ph10 539 not set it from the table. */
998 nigel 91
999 nigel 77 case OP_WHITESPACE:
1000 ph10 539 c = start_bits[1]; /* Save in case it was already set */
1001     set_type_bits(start_bits, cbit_space, table_limit, cd);
1002     start_bits[1] = (start_bits[1] & ~0x08) | c;
1003 nigel 77 try_next = FALSE;
1004     break;
1005    
1006     case OP_NOT_WORDCHAR:
1007 ph10 539 set_nottype_bits(start_bits, cbit_word, table_limit, cd);
1008 nigel 77 try_next = FALSE;
1009     break;
1010    
1011     case OP_WORDCHAR:
1012 ph10 539 set_type_bits(start_bits, cbit_word, table_limit, cd);
1013 nigel 77 try_next = FALSE;
1014     break;
1015 ph10 545
1016 nigel 77 /* One or more character type fudges the pointer and restarts, knowing
1017     it will hit a single character type and stop there. */
1018    
1019     case OP_TYPEPLUS:
1020     case OP_TYPEMINPLUS:
1021 ph10 535 case OP_TYPEPOSPLUS:
1022 nigel 77 tcode++;
1023     break;
1024    
1025     case OP_TYPEEXACT:
1026     tcode += 3;
1027     break;
1028    
1029     /* Zero or more repeats of character types set the bits and then
1030     try again. */
1031    
1032     case OP_TYPEUPTO:
1033     case OP_TYPEMINUPTO:
1034 nigel 93 case OP_TYPEPOSUPTO:
1035 nigel 77 tcode += 2; /* Fall through */
1036    
1037     case OP_TYPESTAR:
1038     case OP_TYPEMINSTAR:
1039 nigel 93 case OP_TYPEPOSSTAR:
1040 nigel 77 case OP_TYPEQUERY:
1041     case OP_TYPEMINQUERY:
1042 nigel 93 case OP_TYPEPOSQUERY:
1043 nigel 77 switch(tcode[1])
1044     {
1045 ph10 523 default:
1046 nigel 77 case OP_ANY:
1047 ph10 345 case OP_ALLANY:
1048 nigel 93 return SSB_FAIL;
1049 ph10 535
1050 ph10 524 case OP_HSPACE:
1051     SET_BIT(0x09);
1052     SET_BIT(0x20);
1053     if (utf8)
1054 ph10 535 {
1055 ph10 545 SET_BIT(0xC2); /* For U+00A0 */
1056 ph10 524 SET_BIT(0xE1); /* For U+1680, U+180E */
1057     SET_BIT(0xE2); /* For U+2000 - U+200A, U+202F, U+205F */
1058 ph10 535 SET_BIT(0xE3); /* For U+3000 */
1059 ph10 524 }
1060 ph10 538 else SET_BIT(0xA0);
1061 ph10 535 break;
1062    
1063     case OP_ANYNL:
1064 ph10 524 case OP_VSPACE:
1065 ph10 535 SET_BIT(0x0A);
1066     SET_BIT(0x0B);
1067     SET_BIT(0x0C);
1068     SET_BIT(0x0D);
1069 ph10 545 if (utf8)
1070 ph10 538 {
1071 ph10 545 SET_BIT(0xC2); /* For U+0085 */
1072 ph10 538 SET_BIT(0xE2); /* For U+2028, U+2029 */
1073 ph10 545 }
1074 ph10 538 else SET_BIT(0x85);
1075 ph10 535 break;
1076    
1077 nigel 77 case OP_NOT_DIGIT:
1078 ph10 539 set_nottype_bits(start_bits, cbit_digit, table_limit, cd);
1079 nigel 77 break;
1080    
1081     case OP_DIGIT:
1082 ph10 539 set_type_bits(start_bits, cbit_digit, table_limit, cd);
1083 nigel 77 break;
1084    
1085 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
1086 ph10 539 ensure it gets set as not whitespace. */
1087 nigel 91
1088 nigel 77 case OP_NOT_WHITESPACE:
1089 ph10 539 set_nottype_bits(start_bits, cbit_space, table_limit, cd);
1090 ph10 545 start_bits[1] |= 0x08;
1091 nigel 77 break;
1092    
1093 nigel 91 /* The cbit_space table has vertical tab as whitespace; we have to
1094 ph10 539 avoid setting it. */
1095 nigel 91
1096 nigel 77 case OP_WHITESPACE:
1097 ph10 539 c = start_bits[1]; /* Save in case it was already set */
1098     set_type_bits(start_bits, cbit_space, table_limit, cd);
1099     start_bits[1] = (start_bits[1] & ~0x08) | c;
1100 nigel 77 break;
1101    
1102     case OP_NOT_WORDCHAR:
1103 ph10 539 set_nottype_bits(start_bits, cbit_word, table_limit, cd);
1104 nigel 77 break;
1105    
1106     case OP_WORDCHAR:
1107 ph10 539 set_type_bits(start_bits, cbit_word, table_limit, cd);
1108 nigel 77 break;
1109     }
1110    
1111     tcode += 2;
1112     break;
1113    
1114     /* Character class where all the information is in a bit map: set the
1115     bits and either carry on or not, according to the repeat count. If it was
1116     a negative class, and we are operating with UTF-8 characters, any byte
1117     with a value >= 0xc4 is a potentially valid starter because it starts a
1118     character with a value > 255. */
1119    
1120     case OP_NCLASS:
1121 ph10 111 #ifdef SUPPORT_UTF8
1122 nigel 77 if (utf8)
1123     {
1124     start_bits[24] |= 0xf0; /* Bits for 0xc4 - 0xc8 */
1125     memset(start_bits+25, 0xff, 7); /* Bits for 0xc9 - 0xff */
1126     }
1127 ph10 111 #endif
1128 nigel 77 /* Fall through */
1129    
1130     case OP_CLASS:
1131     {
1132     tcode++;
1133    
1134     /* In UTF-8 mode, the bits in a bit map correspond to character
1135     values, not to byte values. However, the bit map we are constructing is
1136     for byte values. So we have to do a conversion for characters whose
1137     value is > 127. In fact, there are only two possible starting bytes for
1138     characters in the range 128 - 255. */
1139    
1140 ph10 107 #ifdef SUPPORT_UTF8
1141 nigel 77 if (utf8)
1142     {
1143     for (c = 0; c < 16; c++) start_bits[c] |= tcode[c];
1144     for (c = 128; c < 256; c++)
1145     {
1146     if ((tcode[c/8] && (1 << (c&7))) != 0)
1147     {
1148     int d = (c >> 6) | 0xc0; /* Set bit for this starter */
1149     start_bits[d/8] |= (1 << (d&7)); /* and then skip on to the */
1150     c = (c & 0xc0) + 0x40 - 1; /* next relevant character. */
1151     }
1152     }
1153     }
1154    
1155     /* In non-UTF-8 mode, the two bit maps are completely compatible. */
1156    
1157     else
1158 ph10 111 #endif
1159 nigel 77 {
1160     for (c = 0; c < 32; c++) start_bits[c] |= tcode[c];
1161     }
1162    
1163 ph10 605 /* Advance past the bit map, and act on what follows. For a zero
1164     minimum repeat, continue; otherwise stop processing. */
1165 nigel 77
1166     tcode += 32;
1167     switch (*tcode)
1168     {
1169     case OP_CRSTAR:
1170     case OP_CRMINSTAR:
1171     case OP_CRQUERY:
1172     case OP_CRMINQUERY:
1173     tcode++;
1174     break;
1175    
1176     case OP_CRRANGE:
1177     case OP_CRMINRANGE:
1178     if (((tcode[1] << 8) + tcode[2]) == 0) tcode += 5;
1179     else try_next = FALSE;
1180     break;
1181 ph10 605
1182 nigel 77 default:
1183     try_next = FALSE;
1184     break;
1185     }
1186     }
1187     break; /* End of bitmap class handling */
1188    
1189     } /* End of switch */
1190     } /* End of try_next loop */
1191    
1192     code += GET(code, 1); /* Advance to next branch */
1193     }
1194     while (*code == OP_ALT);
1195 nigel 93 return yield;
1196 nigel 77 }
1197    
1198    
1199    
1200 ph10 605
1201    
1202 nigel 77 /*************************************************
1203     * Study a compiled expression *
1204     *************************************************/
1205    
1206     /* This function is handed a compiled expression that it must study to produce
1207     information that will speed up the matching. It returns a pcre_extra block
1208     which then gets handed back to pcre_exec().
1209    
1210     Arguments:
1211     re points to the compiled expression
1212     options contains option bits
1213     errorptr points to where to place error messages;
1214     set NULL unless error
1215    
1216     Returns: pointer to a pcre_extra block, with study_data filled in and the
1217 ph10 455 appropriate flags set;
1218 nigel 77 NULL on error or if no optimization possible
1219     */
1220    
1221 ph10 359 PCRE_EXP_DEFN pcre_extra * PCRE_CALL_CONVENTION
1222 nigel 77 pcre_study(const pcre *external_re, int options, const char **errorptr)
1223     {
1224 ph10 455 int min;
1225     BOOL bits_set = FALSE;
1226 ph10 612 BOOL had_accept = FALSE;
1227 nigel 77 uschar start_bits[32];
1228     pcre_extra *extra;
1229     pcre_study_data *study;
1230     const uschar *tables;
1231 nigel 91 uschar *code;
1232     compile_data compile_block;
1233 nigel 77 const real_pcre *re = (const real_pcre *)external_re;
1234    
1235     *errorptr = NULL;
1236    
1237     if (re == NULL || re->magic_number != MAGIC_NUMBER)
1238     {
1239     *errorptr = "argument is not a compiled regular expression";
1240     return NULL;
1241     }
1242    
1243     if ((options & ~PUBLIC_STUDY_OPTIONS) != 0)
1244     {
1245     *errorptr = "unknown or incorrect option bit(s) set";
1246     return NULL;
1247     }
1248    
1249 nigel 91 code = (uschar *)re + re->name_table_offset +
1250     (re->name_count * re->name_entry_size);
1251    
1252 nigel 77 /* For an anchored pattern, or an unanchored pattern that has a first char, or
1253 ph10 461 a multiline pattern that matches only at "line starts", there is no point in
1254 ph10 455 seeking a list of starting bytes. */
1255 nigel 77
1256 ph10 455 if ((re->options & PCRE_ANCHORED) == 0 &&
1257     (re->flags & (PCRE_FIRSTSET|PCRE_STARTLINE)) == 0)
1258     {
1259 ph10 605 int rc;
1260    
1261 ph10 455 /* Set the character tables in the block that is passed around */
1262 ph10 461
1263 ph10 455 tables = re->tables;
1264     if (tables == NULL)
1265     (void)pcre_fullinfo(external_re, NULL, PCRE_INFO_DEFAULT_TABLES,
1266     (void *)(&tables));
1267 ph10 461
1268 ph10 455 compile_block.lcc = tables + lcc_offset;
1269     compile_block.fcc = tables + fcc_offset;
1270     compile_block.cbits = tables + cbits_offset;
1271     compile_block.ctypes = tables + ctypes_offset;
1272 ph10 461
1273 ph10 455 /* See if we can find a fixed set of initial characters for the pattern. */
1274 ph10 461
1275 ph10 455 memset(start_bits, 0, 32 * sizeof(uschar));
1276 ph10 605 rc = set_start_bits(code, start_bits, (re->options & PCRE_UTF8) != 0,
1277     &compile_block);
1278     bits_set = rc == SSB_DONE;
1279     if (rc == SSB_UNKNOWN) *errorptr = "internal error: opcode not recognized";
1280 ph10 455 }
1281 ph10 461
1282 ph10 455 /* Find the minimum length of subject string. */
1283 nigel 77
1284 ph10 620 switch(min = find_minlength(code, code, re->options, &had_accept, 0))
1285 ph10 603 {
1286     case -2: *errorptr = "internal error: missing capturing bracket"; break;
1287 ph10 605 case -3: *errorptr = "internal error: opcode not recognized"; break;
1288 ph10 603 default: break;
1289 ph10 605 }
1290 nigel 77
1291 ph10 605 /* Return NULL if there's been an error or if no optimization is possible. */
1292 nigel 77
1293 ph10 605 if (*errorptr != NULL || (!bits_set && min < 0)) return NULL;
1294 nigel 77
1295     /* Get a pcre_extra block and a pcre_study_data block. The study data is put in
1296     the latter, which is pointed to by the former, which may also get additional
1297     data set later by the calling program. At the moment, the size of
1298     pcre_study_data is fixed. We nevertheless save it in a field for returning via
1299     the pcre_fullinfo() function so that if it becomes variable in the future, we
1300     don't have to change that code. */
1301    
1302     extra = (pcre_extra *)(pcre_malloc)
1303     (sizeof(pcre_extra) + sizeof(pcre_study_data));
1304    
1305     if (extra == NULL)
1306     {
1307     *errorptr = "failed to get memory";
1308     return NULL;
1309     }
1310    
1311     study = (pcre_study_data *)((char *)extra + sizeof(pcre_extra));
1312     extra->flags = PCRE_EXTRA_STUDY_DATA;
1313     extra->study_data = study;
1314    
1315     study->size = sizeof(pcre_study_data);
1316 ph10 455 study->flags = 0;
1317 nigel 77
1318 ph10 455 if (bits_set)
1319     {
1320     study->flags |= PCRE_STUDY_MAPPED;
1321     memcpy(study->start_bits, start_bits, sizeof(start_bits));
1322     }
1323 ph10 461
1324 ph10 455 if (min >= 0)
1325     {
1326     study->flags |= PCRE_STUDY_MINLEN;
1327     study->minlength = min;
1328 ph10 461 }
1329 ph10 455
1330 nigel 77 return extra;
1331     }
1332    
1333     /* End of pcre_study.c */

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