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Revision 353 - (show annotations) (download)
Mon Jul 7 15:44:24 2008 UTC (6 years, 5 months ago) by ph10
File MIME type: text/plain
File size: 17950 byte(s)
Fix SKIPZERO bug in pcre_study().

1 /*************************************************
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 Copyright (c) 1997-2008 University of Cambridge
10
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 #ifdef HAVE_CONFIG_H
46 #include "config.h"
47 #endif
48
49 #include "pcre_internal.h"
50
51
52 /* Returns from set_start_bits() */
53
54 enum { SSB_FAIL, SSB_DONE, SSB_CONTINUE };
55
56
57 /*************************************************
58 * Set a bit and maybe its alternate case *
59 *************************************************/
60
61 /* Given a character, set its bit in the table, and also the bit for the other
62 version of a letter if we are caseless.
63
64 Arguments:
65 start_bits points to the bit map
66 c is the character
67 caseless the caseless flag
68 cd the block with char table pointers
69
70 Returns: nothing
71 */
72
73 static void
74 set_bit(uschar *start_bits, unsigned int c, BOOL caseless, compile_data *cd)
75 {
76 start_bits[c/8] |= (1 << (c&7));
77 if (caseless && (cd->ctypes[c] & ctype_letter) != 0)
78 start_bits[cd->fcc[c]/8] |= (1 << (cd->fcc[c]&7));
79 }
80
81
82
83 /*************************************************
84 * Create bitmap of starting bytes *
85 *************************************************/
86
87 /* This function scans a compiled unanchored expression recursively and
88 attempts to build a bitmap of the set of possible starting bytes. As time goes
89 by, we may be able to get more clever at doing this. The SSB_CONTINUE return is
90 useful for parenthesized groups in patterns such as (a*)b where the group
91 provides some optional starting bytes but scanning must continue at the outer
92 level to find at least one mandatory byte. At the outermost level, this
93 function fails unless the result is SSB_DONE.
94
95 Arguments:
96 code points to an expression
97 start_bits points to a 32-byte table, initialized to 0
98 caseless the current state of the caseless flag
99 utf8 TRUE if in UTF-8 mode
100 cd the block with char table pointers
101
102 Returns: SSB_FAIL => Failed to find any starting bytes
103 SSB_DONE => Found mandatory starting bytes
104 SSB_CONTINUE => Found optional starting bytes
105 */
106
107 static int
108 set_start_bits(const uschar *code, uschar *start_bits, BOOL caseless,
109 BOOL utf8, compile_data *cd)
110 {
111 register int c;
112 int yield = SSB_DONE;
113
114 #if 0
115 /* ========================================================================= */
116 /* The following comment and code was inserted in January 1999. In May 2006,
117 when it was observed to cause compiler warnings about unused values, I took it
118 out again. If anybody is still using OS/2, they will have to put it back
119 manually. */
120
121 /* This next statement and the later reference to dummy are here in order to
122 trick the optimizer of the IBM C compiler for OS/2 into generating correct
123 code. Apparently IBM isn't going to fix the problem, and we would rather not
124 disable optimization (in this module it actually makes a big difference, and
125 the pcre module can use all the optimization it can get). */
126
127 volatile int dummy;
128 /* ========================================================================= */
129 #endif
130
131 do
132 {
133 const uschar *tcode = code + (((int)*code == OP_CBRA)? 3:1) + LINK_SIZE;
134 BOOL try_next = TRUE;
135
136 while (try_next) /* Loop for items in this branch */
137 {
138 int rc;
139 switch(*tcode)
140 {
141 /* Fail if we reach something we don't understand */
142
143 default:
144 return SSB_FAIL;
145
146 /* If we hit a bracket or a positive lookahead assertion, recurse to set
147 bits from within the subpattern. If it can't find anything, we have to
148 give up. If it finds some mandatory character(s), we are done for this
149 branch. Otherwise, carry on scanning after the subpattern. */
150
151 case OP_BRA:
152 case OP_SBRA:
153 case OP_CBRA:
154 case OP_SCBRA:
155 case OP_ONCE:
156 case OP_ASSERT:
157 rc = set_start_bits(tcode, start_bits, caseless, utf8, cd);
158 if (rc == SSB_FAIL) return SSB_FAIL;
159 if (rc == SSB_DONE) try_next = FALSE; else
160 {
161 do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
162 tcode += 1 + LINK_SIZE;
163 }
164 break;
165
166 /* If we hit ALT or KET, it means we haven't found anything mandatory in
167 this branch, though we might have found something optional. For ALT, we
168 continue with the next alternative, but we have to arrange that the final
169 result from subpattern is SSB_CONTINUE rather than SSB_DONE. For KET,
170 return SSB_CONTINUE: if this is the top level, that indicates failure,
171 but after a nested subpattern, it causes scanning to continue. */
172
173 case OP_ALT:
174 yield = SSB_CONTINUE;
175 try_next = FALSE;
176 break;
177
178 case OP_KET:
179 case OP_KETRMAX:
180 case OP_KETRMIN:
181 return SSB_CONTINUE;
182
183 /* Skip over callout */
184
185 case OP_CALLOUT:
186 tcode += 2 + 2*LINK_SIZE;
187 break;
188
189 /* Skip over lookbehind and negative lookahead assertions */
190
191 case OP_ASSERT_NOT:
192 case OP_ASSERTBACK:
193 case OP_ASSERTBACK_NOT:
194 do tcode += GET(tcode, 1); while (*tcode == OP_ALT);
195 tcode += 1 + LINK_SIZE;
196 break;
197
198 /* Skip over an option setting, changing the caseless flag */
199
200 case OP_OPT:
201 caseless = (tcode[1] & PCRE_CASELESS) != 0;
202 tcode += 2;
203 break;
204
205 /* BRAZERO does the bracket, but carries on. */
206
207 case OP_BRAZERO:
208 case OP_BRAMINZERO:
209 if (set_start_bits(++tcode, start_bits, caseless, utf8, cd) == SSB_FAIL)
210 return SSB_FAIL;
211 /* =========================================================================
212 See the comment at the head of this function concerning the next line,
213 which was an old fudge for the benefit of OS/2.
214 dummy = 1;
215 ========================================================================= */
216 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
217 tcode += 1 + LINK_SIZE;
218 break;
219
220 /* SKIPZERO skips the bracket. */
221
222 case OP_SKIPZERO:
223 tcode++;
224 do tcode += GET(tcode,1); while (*tcode == OP_ALT);
225 tcode += 1 + LINK_SIZE;
226 break;
227
228 /* Single-char * or ? sets the bit and tries the next item */
229
230 case OP_STAR:
231 case OP_MINSTAR:
232 case OP_POSSTAR:
233 case OP_QUERY:
234 case OP_MINQUERY:
235 case OP_POSQUERY:
236 set_bit(start_bits, tcode[1], caseless, cd);
237 tcode += 2;
238 #ifdef SUPPORT_UTF8
239 if (utf8 && tcode[-1] >= 0xc0)
240 tcode += _pcre_utf8_table4[tcode[-1] & 0x3f];
241 #endif
242 break;
243
244 /* Single-char upto sets the bit and tries the next */
245
246 case OP_UPTO:
247 case OP_MINUPTO:
248 case OP_POSUPTO:
249 set_bit(start_bits, tcode[3], caseless, cd);
250 tcode += 4;
251 #ifdef SUPPORT_UTF8
252 if (utf8 && tcode[-1] >= 0xc0)
253 tcode += _pcre_utf8_table4[tcode[-1] & 0x3f];
254 #endif
255 break;
256
257 /* At least one single char sets the bit and stops */
258
259 case OP_EXACT: /* Fall through */
260 tcode += 2;
261
262 case OP_CHAR:
263 case OP_CHARNC:
264 case OP_PLUS:
265 case OP_MINPLUS:
266 case OP_POSPLUS:
267 set_bit(start_bits, tcode[1], caseless, cd);
268 try_next = FALSE;
269 break;
270
271 /* Single character type sets the bits and stops */
272
273 case OP_NOT_DIGIT:
274 for (c = 0; c < 32; c++)
275 start_bits[c] |= ~cd->cbits[c+cbit_digit];
276 try_next = FALSE;
277 break;
278
279 case OP_DIGIT:
280 for (c = 0; c < 32; c++)
281 start_bits[c] |= cd->cbits[c+cbit_digit];
282 try_next = FALSE;
283 break;
284
285 /* The cbit_space table has vertical tab as whitespace; we have to
286 discard it. */
287
288 case OP_NOT_WHITESPACE:
289 for (c = 0; c < 32; c++)
290 {
291 int d = cd->cbits[c+cbit_space];
292 if (c == 1) d &= ~0x08;
293 start_bits[c] |= ~d;
294 }
295 try_next = FALSE;
296 break;
297
298 /* The cbit_space table has vertical tab as whitespace; we have to
299 discard it. */
300
301 case OP_WHITESPACE:
302 for (c = 0; c < 32; c++)
303 {
304 int d = cd->cbits[c+cbit_space];
305 if (c == 1) d &= ~0x08;
306 start_bits[c] |= d;
307 }
308 try_next = FALSE;
309 break;
310
311 case OP_NOT_WORDCHAR:
312 for (c = 0; c < 32; c++)
313 start_bits[c] |= ~cd->cbits[c+cbit_word];
314 try_next = FALSE;
315 break;
316
317 case OP_WORDCHAR:
318 for (c = 0; c < 32; c++)
319 start_bits[c] |= cd->cbits[c+cbit_word];
320 try_next = FALSE;
321 break;
322
323 /* One or more character type fudges the pointer and restarts, knowing
324 it will hit a single character type and stop there. */
325
326 case OP_TYPEPLUS:
327 case OP_TYPEMINPLUS:
328 tcode++;
329 break;
330
331 case OP_TYPEEXACT:
332 tcode += 3;
333 break;
334
335 /* Zero or more repeats of character types set the bits and then
336 try again. */
337
338 case OP_TYPEUPTO:
339 case OP_TYPEMINUPTO:
340 case OP_TYPEPOSUPTO:
341 tcode += 2; /* Fall through */
342
343 case OP_TYPESTAR:
344 case OP_TYPEMINSTAR:
345 case OP_TYPEPOSSTAR:
346 case OP_TYPEQUERY:
347 case OP_TYPEMINQUERY:
348 case OP_TYPEPOSQUERY:
349 switch(tcode[1])
350 {
351 case OP_ANY:
352 case OP_ALLANY:
353 return SSB_FAIL;
354
355 case OP_NOT_DIGIT:
356 for (c = 0; c < 32; c++)
357 start_bits[c] |= ~cd->cbits[c+cbit_digit];
358 break;
359
360 case OP_DIGIT:
361 for (c = 0; c < 32; c++)
362 start_bits[c] |= cd->cbits[c+cbit_digit];
363 break;
364
365 /* The cbit_space table has vertical tab as whitespace; we have to
366 discard it. */
367
368 case OP_NOT_WHITESPACE:
369 for (c = 0; c < 32; c++)
370 {
371 int d = cd->cbits[c+cbit_space];
372 if (c == 1) d &= ~0x08;
373 start_bits[c] |= ~d;
374 }
375 break;
376
377 /* The cbit_space table has vertical tab as whitespace; we have to
378 discard it. */
379
380 case OP_WHITESPACE:
381 for (c = 0; c < 32; c++)
382 {
383 int d = cd->cbits[c+cbit_space];
384 if (c == 1) d &= ~0x08;
385 start_bits[c] |= d;
386 }
387 break;
388
389 case OP_NOT_WORDCHAR:
390 for (c = 0; c < 32; c++)
391 start_bits[c] |= ~cd->cbits[c+cbit_word];
392 break;
393
394 case OP_WORDCHAR:
395 for (c = 0; c < 32; c++)
396 start_bits[c] |= cd->cbits[c+cbit_word];
397 break;
398 }
399
400 tcode += 2;
401 break;
402
403 /* Character class where all the information is in a bit map: set the
404 bits and either carry on or not, according to the repeat count. If it was
405 a negative class, and we are operating with UTF-8 characters, any byte
406 with a value >= 0xc4 is a potentially valid starter because it starts a
407 character with a value > 255. */
408
409 case OP_NCLASS:
410 #ifdef SUPPORT_UTF8
411 if (utf8)
412 {
413 start_bits[24] |= 0xf0; /* Bits for 0xc4 - 0xc8 */
414 memset(start_bits+25, 0xff, 7); /* Bits for 0xc9 - 0xff */
415 }
416 #endif
417 /* Fall through */
418
419 case OP_CLASS:
420 {
421 tcode++;
422
423 /* In UTF-8 mode, the bits in a bit map correspond to character
424 values, not to byte values. However, the bit map we are constructing is
425 for byte values. So we have to do a conversion for characters whose
426 value is > 127. In fact, there are only two possible starting bytes for
427 characters in the range 128 - 255. */
428
429 #ifdef SUPPORT_UTF8
430 if (utf8)
431 {
432 for (c = 0; c < 16; c++) start_bits[c] |= tcode[c];
433 for (c = 128; c < 256; c++)
434 {
435 if ((tcode[c/8] && (1 << (c&7))) != 0)
436 {
437 int d = (c >> 6) | 0xc0; /* Set bit for this starter */
438 start_bits[d/8] |= (1 << (d&7)); /* and then skip on to the */
439 c = (c & 0xc0) + 0x40 - 1; /* next relevant character. */
440 }
441 }
442 }
443
444 /* In non-UTF-8 mode, the two bit maps are completely compatible. */
445
446 else
447 #endif
448 {
449 for (c = 0; c < 32; c++) start_bits[c] |= tcode[c];
450 }
451
452 /* Advance past the bit map, and act on what follows */
453
454 tcode += 32;
455 switch (*tcode)
456 {
457 case OP_CRSTAR:
458 case OP_CRMINSTAR:
459 case OP_CRQUERY:
460 case OP_CRMINQUERY:
461 tcode++;
462 break;
463
464 case OP_CRRANGE:
465 case OP_CRMINRANGE:
466 if (((tcode[1] << 8) + tcode[2]) == 0) tcode += 5;
467 else try_next = FALSE;
468 break;
469
470 default:
471 try_next = FALSE;
472 break;
473 }
474 }
475 break; /* End of bitmap class handling */
476
477 } /* End of switch */
478 } /* End of try_next loop */
479
480 code += GET(code, 1); /* Advance to next branch */
481 }
482 while (*code == OP_ALT);
483 return yield;
484 }
485
486
487
488 /*************************************************
489 * Study a compiled expression *
490 *************************************************/
491
492 /* This function is handed a compiled expression that it must study to produce
493 information that will speed up the matching. It returns a pcre_extra block
494 which then gets handed back to pcre_exec().
495
496 Arguments:
497 re points to the compiled expression
498 options contains option bits
499 errorptr points to where to place error messages;
500 set NULL unless error
501
502 Returns: pointer to a pcre_extra block, with study_data filled in and the
503 appropriate flag set;
504 NULL on error or if no optimization possible
505 */
506
507 PCRE_EXP_DEFN pcre_extra *
508 pcre_study(const pcre *external_re, int options, const char **errorptr)
509 {
510 uschar start_bits[32];
511 pcre_extra *extra;
512 pcre_study_data *study;
513 const uschar *tables;
514 uschar *code;
515 compile_data compile_block;
516 const real_pcre *re = (const real_pcre *)external_re;
517
518 *errorptr = NULL;
519
520 if (re == NULL || re->magic_number != MAGIC_NUMBER)
521 {
522 *errorptr = "argument is not a compiled regular expression";
523 return NULL;
524 }
525
526 if ((options & ~PUBLIC_STUDY_OPTIONS) != 0)
527 {
528 *errorptr = "unknown or incorrect option bit(s) set";
529 return NULL;
530 }
531
532 code = (uschar *)re + re->name_table_offset +
533 (re->name_count * re->name_entry_size);
534
535 /* For an anchored pattern, or an unanchored pattern that has a first char, or
536 a multiline pattern that matches only at "line starts", no further processing
537 at present. */
538
539 if ((re->options & PCRE_ANCHORED) != 0 ||
540 (re->flags & (PCRE_FIRSTSET|PCRE_STARTLINE)) != 0)
541 return NULL;
542
543 /* Set the character tables in the block that is passed around */
544
545 tables = re->tables;
546 if (tables == NULL)
547 (void)pcre_fullinfo(external_re, NULL, PCRE_INFO_DEFAULT_TABLES,
548 (void *)(&tables));
549
550 compile_block.lcc = tables + lcc_offset;
551 compile_block.fcc = tables + fcc_offset;
552 compile_block.cbits = tables + cbits_offset;
553 compile_block.ctypes = tables + ctypes_offset;
554
555 /* See if we can find a fixed set of initial characters for the pattern. */
556
557 memset(start_bits, 0, 32 * sizeof(uschar));
558 if (set_start_bits(code, start_bits, (re->options & PCRE_CASELESS) != 0,
559 (re->options & PCRE_UTF8) != 0, &compile_block) != SSB_DONE) return NULL;
560
561 /* Get a pcre_extra block and a pcre_study_data block. The study data is put in
562 the latter, which is pointed to by the former, which may also get additional
563 data set later by the calling program. At the moment, the size of
564 pcre_study_data is fixed. We nevertheless save it in a field for returning via
565 the pcre_fullinfo() function so that if it becomes variable in the future, we
566 don't have to change that code. */
567
568 extra = (pcre_extra *)(pcre_malloc)
569 (sizeof(pcre_extra) + sizeof(pcre_study_data));
570
571 if (extra == NULL)
572 {
573 *errorptr = "failed to get memory";
574 return NULL;
575 }
576
577 study = (pcre_study_data *)((char *)extra + sizeof(pcre_extra));
578 extra->flags = PCRE_EXTRA_STUDY_DATA;
579 extra->study_data = study;
580
581 study->size = sizeof(pcre_study_data);
582 study->options = PCRE_STUDY_MAPPED;
583 memcpy(study->start_bits, start_bits, sizeof(start_bits));
584
585 return extra;
586 }
587
588 /* End of pcre_study.c */

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