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Revision 171 - (show annotations) (download)
Mon Jun 4 14:28:58 2007 UTC (7 years, 5 months ago) by ph10
File size: 128864 byte(s)
Support \k{name} and \g{name} a la Perl 5.10.

1 ChangeLog for PCRE
2 ------------------
3
4 Version 7.2 01-May-07
5 ---------------------
6
7 1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
8 which is apparently normally available under Windows.
9
10 2. Re-jig the pcregrep tests with different newline settings in an attempt
11 to make them independent of the local environment's newline setting.
12
13 3. Add code to configure.ac to remove -g from the CFLAGS default settings.
14
15 4. Some of the "internals" tests were previously cut out when the link size
16 was not 2, because the output contained actual offsets. The recent new
17 "Z" feature of pcretest means that these can be cut out, making the tests
18 usable with all link sizes.
19
20 5. Implemented Stan Switzer's goto replacement for longjmp() when not using
21 stack recursion. This gives a massive performance boost under BSD, but just
22 a small improvement under Linux. However, it saves one field in the frame
23 in all cases.
24
25 6. Added more features from the forthcoming Perl 5.10:
26
27 (a) (?-n) (where n is a string of digits) is a relative subroutine or
28 recursion call. It refers to the nth most recently opened parentheses.
29
30 (b) (?+n) is also a relative subroutine call; it refers to the nth next
31 to be opened parentheses.
32
33 (c) Conditions that refer to capturing parentheses can be specified
34 relatively, for example, (?(-2)... or (?(+3)...
35
36 (d) \K resets the start of the current match so that everything before
37 is not part of it.
38
39 (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
40
41 (f) \g{name} is another synonym - part of Perl 5.10's unification of
42 reference syntax.
43
44 7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
45 PCRE_INFO_JCHANGED.
46
47 8. A pattern such as (.*(.)?)* caused pcre_exec() to fail by either not
48 terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
49 for detecting groups that can match an empty string.
50
51
52 Version 7.1 24-Apr-07
53 ---------------------
54
55 1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
56 that is more "standard", making use of automake and other Autotools. There
57 is some re-arrangement of the files and adjustment of comments consequent
58 on this.
59
60 2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
61 for recursive directory scanning broke on some systems because the files
62 are not scanned in any specific order and on different systems the order
63 was different. A call to "sort" has been inserted into RunGrepTest for the
64 approprate test as a short-term fix. In the longer term there may be an
65 alternative.
66
67 3. I had an email from Eric Raymond about problems translating some of PCRE's
68 man pages to HTML (despite the fact that I distribute HTML pages, some
69 people do their own conversions for various reasons). The problems
70 concerned the use of low-level troff macros .br and .in. I have therefore
71 removed all such uses from the man pages (some were redundant, some could
72 be replaced by .nf/.fi pairs). The 132html script that I use to generate
73 HTML has been updated to handle .nf/.fi and to complain if it encounters
74 .br or .in.
75
76 4. Updated comments in configure.ac that get placed in config.h.in and also
77 arranged for config.h to be included in the distribution, with the name
78 config.h.generic, for the benefit of those who have to compile without
79 Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
80
81 5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
82 Weber: (1) pcre_internal.h was missing some function renames; (2) updated
83 makevp.bat for the current PCRE, using the additional files
84 makevp_c.txt, makevp_l.txt, and pcregexp.pas.
85
86 6. A Windows user reported a minor discrepancy with test 2, which turned out
87 to be caused by a trailing space on an input line that had got lost in his
88 copy. The trailing space was an accident, so I've just removed it.
89
90 7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
91 that is needed.
92
93 8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
94 as "const" (a) because they are and (b) because it helps the PHP
95 maintainers who have recently made a script to detect big data structures
96 in the php code that should be moved to the .rodata section. I remembered
97 to update Builducptable as well, so it won't revert if ucptable.h is ever
98 re-created.
99
100 9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
101 pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
102 order to be able to cut out the UTF-8 tables in the latter when UTF-8
103 support is not required. This saves 1.5-2K of code, which is important in
104 some applications.
105
106 Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
107 so as not to refer to the tables, even though these functions will never be
108 called when UTF-8 support is disabled. Otherwise there are problems with a
109 shared library.
110
111 10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
112
113 (a) It was defining its arguments as char * instead of void *.
114
115 (b) It was assuming that all moves were upwards in memory; this was true
116 a long time ago when I wrote it, but is no longer the case.
117
118 The emulated memove() is provided for those environments that have neither
119 memmove() nor bcopy(). I didn't think anyone used it these days, but that
120 is clearly not the case, as these two bugs were recently reported.
121
122 11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
123 and Detrail to create the HTML documentation, the .txt form of the man
124 pages, and it removes trailing spaces from listed files. It also creates
125 pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
126 case, it wraps all the #defines with #ifndefs. This script should be run
127 before "make dist".
128
129 12. Fixed two fairly obscure bugs concerned with quantified caseless matching
130 with Unicode property support.
131
132 (a) For a maximizing quantifier, if the two different cases of the
133 character were of different lengths in their UTF-8 codings (there are
134 some cases like this - I found 11), and the matching function had to
135 back up over a mixture of the two cases, it incorrectly assumed they
136 were both the same length.
137
138 (b) When PCRE was configured to use the heap rather than the stack for
139 recursion during matching, it was not correctly preserving the data for
140 the other case of a UTF-8 character when checking ahead for a match
141 while processing a minimizing repeat. If the check also involved
142 matching a wide character, but failed, corruption could cause an
143 erroneous result when trying to check for a repeat of the original
144 character.
145
146 13. Some tidying changes to the testing mechanism:
147
148 (a) The RunTest script now detects the internal link size and whether there
149 is UTF-8 and UCP support by running ./pcretest -C instead of relying on
150 values substituted by "configure". (The RunGrepTest script already did
151 this for UTF-8.) The configure.ac script no longer substitutes the
152 relevant variables.
153
154 (b) The debugging options /B and /D in pcretest show the compiled bytecode
155 with length and offset values. This means that the output is different
156 for different internal link sizes. Test 2 is skipped for link sizes
157 other than 2 because of this, bypassing the problem. Unfortunately,
158 there was also a test in test 3 (the locale tests) that used /B and
159 failed for link sizes other than 2. Rather than cut the whole test out,
160 I have added a new /Z option to pcretest that replaces the length and
161 offset values with spaces. This is now used to make test 3 independent
162 of link size. (Test 2 will be tidied up later.)
163
164 14. If erroroffset was passed as NULL to pcre_compile, it provoked a
165 segmentation fault instead of returning the appropriate error message.
166
167 15. In multiline mode when the newline sequence was set to "any", the pattern
168 ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
169 This doesn't seem right; it now treats the CRLF combination as the line
170 ending, and so does not match in that case. It's only a pattern such as ^$
171 that would hit this one: something like ^ABC$ would have failed after \r
172 and then tried again after \r\n.
173
174 16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
175 in an attempt to make files that differ only in their line terminators
176 compare equal. This works on Linux.
177
178 17. Under certain error circumstances pcregrep might try to free random memory
179 as it exited. This is now fixed, thanks to valgrind.
180
181 19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
182 "abc\r\n\r\n", it found an unwanted second match after the second \r. This
183 was because its rules for how to advance for /g after matching an empty
184 string at the end of a line did not allow for this case. They now check for
185 it specially.
186
187 20. pcretest is supposed to handle patterns and data of any length, by
188 extending its buffers when necessary. It was getting this wrong when the
189 buffer for a data line had to be extended.
190
191 21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
192 CRLF as a newline sequence.
193
194 22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
195 out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
196 I have nevertheless tidied it up.
197
198 23. Added some casts to kill warnings from HP-UX ia64 compiler.
199
200 24. Added a man page for pcre-config.
201
202
203 Version 7.0 19-Dec-06
204 ---------------------
205
206 1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
207 moving to gcc 4.1.1.
208
209 2. The -S option for pcretest uses setrlimit(); I had omitted to #include
210 sys/time.h, which is documented as needed for this function. It doesn't
211 seem to matter on Linux, but it showed up on some releases of OS X.
212
213 3. It seems that there are systems where bytes whose values are greater than
214 127 match isprint() in the "C" locale. The "C" locale should be the
215 default when a C program starts up. In most systems, only ASCII printing
216 characters match isprint(). This difference caused the output from pcretest
217 to vary, making some of the tests fail. I have changed pcretest so that:
218
219 (a) When it is outputting text in the compiled version of a pattern, bytes
220 other than 32-126 are always shown as hex escapes.
221
222 (b) When it is outputting text that is a matched part of a subject string,
223 it does the same, unless a different locale has been set for the match
224 (using the /L modifier). In this case, it uses isprint() to decide.
225
226 4. Fixed a major bug that caused incorrect computation of the amount of memory
227 required for a compiled pattern when options that changed within the
228 pattern affected the logic of the preliminary scan that determines the
229 length. The relevant options are -x, and -i in UTF-8 mode. The result was
230 that the computed length was too small. The symptoms of this bug were
231 either the PCRE error "internal error: code overflow" from pcre_compile(),
232 or a glibc crash with a message such as "pcretest: free(): invalid next
233 size (fast)". Examples of patterns that provoked this bug (shown in
234 pcretest format) are:
235
236 /(?-x: )/x
237 /(?x)(?-x: \s*#\s*)/
238 /((?i)[\x{c0}])/8
239 /(?i:[\x{c0}])/8
240
241 HOWEVER: Change 17 below makes this fix obsolete as the memory computation
242 is now done differently.
243
244 5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
245 wrapper classes; (b) implement a new function in the C++ scanner that is
246 more efficient than the old way of doing things because it avoids levels of
247 recursion in the regex matching; (c) add a paragraph to the documentation
248 for the FullMatch() function.
249
250 6. The escape sequence \n was being treated as whatever was defined as
251 "newline". Not only was this contrary to the documentation, which states
252 that \n is character 10 (hex 0A), but it also went horribly wrong when
253 "newline" was defined as CRLF. This has been fixed.
254
255 7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
256 was being set to -1 for the "end of line" case (supposedly a value that no
257 character can have). Though this value is never used (the check for end of
258 line is "zero bytes in current character"), it caused compiler complaints.
259 I've changed it to 0xffffffff.
260
261 8. In pcre_version.c, the version string was being built by a sequence of
262 C macros that, in the event of PCRE_PRERELEASE being defined as an empty
263 string (as it is for production releases) called a macro with an empty
264 argument. The C standard says the result of this is undefined. The gcc
265 compiler treats it as an empty string (which was what was wanted) but it is
266 reported that Visual C gives an error. The source has been hacked around to
267 avoid this problem.
268
269 9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
270 builds of pcretest, and changed the call to _setmode() to use _O_BINARY
271 instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
272 of them did).
273
274 10. Originally, pcretest opened its input and output without "b"; then I was
275 told that "b" was needed in some environments, so it was added for release
276 5.0 to both the input and output. (It makes no difference on Unix-like
277 systems.) Later I was told that it is wrong for the input on Windows. I've
278 now abstracted the modes into two macros, to make it easier to fiddle with
279 them, and removed "b" from the input mode under Windows.
280
281 11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
282
283 12. Added -help and --help to pcretest as an official way of being reminded
284 of the options.
285
286 13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
287 and pcrecpp.cc because they annoy compilers at high warning levels.
288
289 14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
290
291 15. Fixed an occurrence of == in configure.ac that should have been = (shell
292 scripts are not C programs :-) and which was not noticed because it works
293 on Linux.
294
295 16. pcretest is supposed to handle any length of pattern and data line (as one
296 line or as a continued sequence of lines) by extending its input buffer if
297 necessary. This feature was broken for very long pattern lines, leading to
298 a string of junk being passed to pcre_compile() if the pattern was longer
299 than about 50K.
300
301 17. I have done a major re-factoring of the way pcre_compile() computes the
302 amount of memory needed for a compiled pattern. Previously, there was code
303 that made a preliminary scan of the pattern in order to do this. That was
304 OK when PCRE was new, but as the facilities have expanded, it has become
305 harder and harder to keep it in step with the real compile phase, and there
306 have been a number of bugs (see for example, 4 above). I have now found a
307 cunning way of running the real compile function in a "fake" mode that
308 enables it to compute how much memory it would need, while actually only
309 ever using a few hundred bytes of working memory and without too many
310 tests of the mode. This should make future maintenance and development
311 easier. A side effect of this work is that the limit of 200 on the nesting
312 depth of parentheses has been removed (though this was never a serious
313 limitation, I suspect). However, there is a downside: pcre_compile() now
314 runs more slowly than before (30% or more, depending on the pattern). I
315 hope this isn't a big issue. There is no effect on runtime performance.
316
317 18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
318 newline (only possible for the last line of a file) and it was a
319 pattern that set a locale (followed by /Lsomething), pcretest crashed.
320
321 19. Added additional timing features to pcretest. (1) The -tm option now times
322 matching only, not compiling. (2) Both -t and -tm can be followed, as a
323 separate command line item, by a number that specifies the number of
324 repeats to use when timing. The default is 50000; this gives better
325 precision, but takes uncomfortably long for very large patterns.
326
327 20. Extended pcre_study() to be more clever in cases where a branch of a
328 subpattern has no definite first character. For example, (a*|b*)[cd] would
329 previously give no result from pcre_study(). Now it recognizes that the
330 first character must be a, b, c, or d.
331
332 21. There was an incorrect error "recursive call could loop indefinitely" if
333 a subpattern (or the entire pattern) that was being tested for matching an
334 empty string contained only one non-empty item after a nested subpattern.
335 For example, the pattern (?>\x{100}*)\d(?R) provoked this error
336 incorrectly, because the \d was being skipped in the check.
337
338 22. The pcretest program now has a new pattern option /B and a command line
339 option -b, which is equivalent to adding /B to every pattern. This causes
340 it to show the compiled bytecode, without the additional information that
341 -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
342 is the same as /B/I).
343
344 23. A new optimization is now able automatically to treat some sequences such
345 as a*b as a*+b. More specifically, if something simple (such as a character
346 or a simple class like \d) has an unlimited quantifier, and is followed by
347 something that cannot possibly match the quantified thing, the quantifier
348 is automatically "possessified".
349
350 24. A recursive reference to a subpattern whose number was greater than 39
351 went wrong under certain circumstances in UTF-8 mode. This bug could also
352 have affected the operation of pcre_study().
353
354 25. Realized that a little bit of performance could be had by replacing
355 (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
356
357 26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
358
359 27. Possessive quantifiers such as a++ were previously implemented by turning
360 them into atomic groups such as ($>a+). Now they have their own opcodes,
361 which improves performance. This includes the automatically created ones
362 from 23 above.
363
364 28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
365 lookahead was broken if it was not anchored. PCRE was mistakenly expecting
366 the first matched character to be a colon. This applied both to named and
367 numbered groups.
368
369 29. The ucpinternal.h header file was missing its idempotency #ifdef.
370
371 30. I was sent a "project" file called libpcre.a.dev which I understand makes
372 building PCRE on Windows easier, so I have included it in the distribution.
373
374 31. There is now a check in pcretest against a ridiculously large number being
375 returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
376 loop, the loop is abandoned.
377
378 32. Forward references to subpatterns in conditions such as (?(2)...) where
379 subpattern 2 is defined later cause pcre_compile() to search forwards in
380 the pattern for the relevant set of parentheses. This search went wrong
381 when there were unescaped parentheses in a character class, parentheses
382 escaped with \Q...\E, or parentheses in a #-comment in /x mode.
383
384 33. "Subroutine" calls and backreferences were previously restricted to
385 referencing subpatterns earlier in the regex. This restriction has now
386 been removed.
387
388 34. Added a number of extra features that are going to be in Perl 5.10. On the
389 whole, these are just syntactic alternatives for features that PCRE had
390 previously implemented using the Python syntax or my own invention. The
391 other formats are all retained for compatibility.
392
393 (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
394 as (?P<name>...). The new forms, as well as being in Perl 5.10, are
395 also .NET compatible.
396
397 (b) A recursion or subroutine call to a named group can now be defined as
398 (?&name) as well as (?P>name).
399
400 (c) A backreference to a named group can now be defined as \k<name> or
401 \k'name' as well as (?P=name). The new forms, as well as being in Perl
402 5.10, are also .NET compatible.
403
404 (d) A conditional reference to a named group can now use the syntax
405 (?(<name>) or (?('name') as well as (?(name).
406
407 (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
408 groups (named and numbered) that are never evaluated inline, but can be
409 called as "subroutines" from elsewhere. In effect, the DEFINE condition
410 is always false. There may be only one alternative in such a group.
411
412 (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
413 as the simple (?(R). The condition is true only if the most recent
414 recursion is that of the given number or name. It does not search out
415 through the entire recursion stack.
416
417 (g) The escape \gN or \g{N} has been added, where N is a positive or
418 negative number, specifying an absolute or relative reference.
419
420 35. Tidied to get rid of some further signed/unsigned compiler warnings and
421 some "unreachable code" warnings.
422
423 36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
424 things, this adds five new scripts.
425
426 37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
427 There were also incompatibilities regarding the handling of \Q..\E inside
428 character classes, for example with patterns like [\Qa\E-\Qz\E] where the
429 hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
430
431 38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
432 matches an empty string, and forcibly breaks the loop. There were bugs in
433 this code in non-simple cases. For a pattern such as ^(a()*)* matched
434 against aaaa the result was just "a" rather than "aaaa", for example. Two
435 separate and independent bugs (that affected different cases) have been
436 fixed.
437
438 39. Refactored the code to abolish the use of different opcodes for small
439 capturing bracket numbers. This is a tidy that I avoided doing when I
440 removed the limit on the number of capturing brackets for 3.5 back in 2001.
441 The new approach is not only tidier, it makes it possible to reduce the
442 memory needed to fix the previous bug (38).
443
444 40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
445 sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
446 processing dot, circumflex, or dollar metacharacters, or #-comments in /x
447 mode.
448
449 41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
450 report.
451
452 42. Applied patch, originally from Ari Pollak, modified by Google, to allow
453 copy construction and assignment in the C++ wrapper.
454
455 43. Updated pcregrep to support "--newline=any". In the process, I fixed a
456 couple of bugs that could have given wrong results in the "--newline=crlf"
457 case.
458
459 44. Added a number of casts and did some reorganization of signed/unsigned int
460 variables following suggestions from Dair Grant. Also renamed the variable
461 "this" as "item" because it is a C++ keyword.
462
463 45. Arranged for dftables to add
464
465 #include "pcre_internal.h"
466
467 to pcre_chartables.c because without it, gcc 4.x may remove the array
468 definition from the final binary if PCRE is built into a static library and
469 dead code stripping is activated.
470
471 46. For an unanchored pattern, if a match attempt fails at the start of a
472 newline sequence, and the newline setting is CRLF or ANY, and the next two
473 characters are CRLF, advance by two characters instead of one.
474
475
476 Version 6.7 04-Jul-06
477 ---------------------
478
479 1. In order to handle tests when input lines are enormously long, pcretest has
480 been re-factored so that it automatically extends its buffers when
481 necessary. The code is crude, but this _is_ just a test program. The
482 default size has been increased from 32K to 50K.
483
484 2. The code in pcre_study() was using the value of the re argument before
485 testing it for NULL. (Of course, in any sensible call of the function, it
486 won't be NULL.)
487
488 3. The memmove() emulation function in pcre_internal.h, which is used on
489 systems that lack both memmove() and bcopy() - that is, hardly ever -
490 was missing a "static" storage class specifier.
491
492 4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
493 containing an extended class (one that cannot be represented by a bitmap
494 because it contains high-valued characters or Unicode property items, e.g.
495 [\pZ]). Almost always one would set UTF-8 mode when processing such a
496 pattern, but PCRE should not loop if you do not (it no longer does).
497 [Detail: two cases were found: (a) a repeated subpattern containing an
498 extended class; (b) a recursive reference to a subpattern that followed a
499 previous extended class. It wasn't skipping over the extended class
500 correctly when UTF-8 mode was not set.]
501
502 5. A negated single-character class was not being recognized as fixed-length
503 in lookbehind assertions such as (?<=[^f]), leading to an incorrect
504 compile error "lookbehind assertion is not fixed length".
505
506 6. The RunPerlTest auxiliary script was showing an unexpected difference
507 between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
508 write a Perl script that can interpret lines of an input file either as
509 byte characters or as UTF-8, which is what "perltest" was being required to
510 do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
511 can't do is switch easily at run time between having the "use utf8;" pragma
512 or not. In the end, I fudged it by using the RunPerlTest script to insert
513 "use utf8;" explicitly for the UTF-8 tests.
514
515 7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
516 the end of the subject string, contrary to the documentation and to what
517 Perl does. This was true of both matching functions. Now it matches only at
518 the start of the subject and immediately after *internal* newlines.
519
520 8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
521 a pointer to an int instead of a pointer to an unsigned long int. This
522 caused problems on 64-bit systems.
523
524 9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
525 instance of the 'standard' template library not being so standard".
526
527 10. There was no check on the number of named subpatterns nor the maximum
528 length of a subpattern name. The product of these values is used to compute
529 the size of the memory block for a compiled pattern. By supplying a very
530 long subpattern name and a large number of named subpatterns, the size
531 computation could be caused to overflow. This is now prevented by limiting
532 the length of names to 32 characters, and the number of named subpatterns
533 to 10,000.
534
535 11. Subpatterns that are repeated with specific counts have to be replicated in
536 the compiled pattern. The size of memory for this was computed from the
537 length of the subpattern and the repeat count. The latter is limited to
538 65535, but there was no limit on the former, meaning that integer overflow
539 could in principle occur. The compiled length of a repeated subpattern is
540 now limited to 30,000 bytes in order to prevent this.
541
542 12. Added the optional facility to have named substrings with the same name.
543
544 13. Added the ability to use a named substring as a condition, using the
545 Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
546 are numbers (not recommended). Forward references are permitted.
547
548 14. Added forward references in named backreferences (if you see what I mean).
549
550 15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
551 pattern could run off the end of the subject. For example, the pattern
552 "(?s)(.{1,5})"8 did this with the subject "ab".
553
554 16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
555 PCRE_CASELESS was set when matching characters that were quantified with ?
556 or *.
557
558 17. A character class other than a single negated character that had a minimum
559 but no maximum quantifier - for example [ab]{6,} - was not handled
560 correctly by pce_dfa_exec(). It would match only one character.
561
562 18. A valid (though odd) pattern that looked like a POSIX character
563 class but used an invalid character after [ (for example [[,abc,]]) caused
564 pcre_compile() to give the error "Failed: internal error: code overflow" or
565 in some cases to crash with a glibc free() error. This could even happen if
566 the pattern terminated after [[ but there just happened to be a sequence of
567 letters, a binary zero, and a closing ] in the memory that followed.
568
569 19. Perl's treatment of octal escapes in the range \400 to \777 has changed
570 over the years. Originally (before any Unicode support), just the bottom 8
571 bits were taken. Thus, for example, \500 really meant \100. Nowadays the
572 output from "man perlunicode" includes this:
573
574 The regular expression compiler produces polymorphic opcodes. That
575 is, the pattern adapts to the data and automatically switches to
576 the Unicode character scheme when presented with Unicode data--or
577 instead uses a traditional byte scheme when presented with byte
578 data.
579
580 Sadly, a wide octal escape does not cause a switch, and in a string with
581 no other multibyte characters, these octal escapes are treated as before.
582 Thus, in Perl, the pattern /\500/ actually matches \100 but the pattern
583 /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
584 Unicode string.
585
586 I have not perpetrated such confusion in PCRE. Up till now, it took just
587 the bottom 8 bits, as in old Perl. I have now made octal escapes with
588 values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
589 translate to the appropriate multibyte character.
590
591 29. Applied some refactoring to reduce the number of warnings from Microsoft
592 and Borland compilers. This has included removing the fudge introduced
593 seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
594 a warning about an unused variable.
595
596 21. PCRE has not included VT (character 0x0b) in the set of whitespace
597 characters since release 4.0, because Perl (from release 5.004) does not.
598 [Or at least, is documented not to: some releases seem to be in conflict
599 with the documentation.] However, when a pattern was studied with
600 pcre_study() and all its branches started with \s, PCRE still included VT
601 as a possible starting character. Of course, this did no harm; it just
602 caused an unnecessary match attempt.
603
604 22. Removed a now-redundant internal flag bit that recorded the fact that case
605 dependency changed within the pattern. This was once needed for "required
606 byte" processing, but is no longer used. This recovers a now-scarce options
607 bit. Also moved the least significant internal flag bit to the most-
608 significant bit of the word, which was not previously used (hangover from
609 the days when it was an int rather than a uint) to free up another bit for
610 the future.
611
612 23. Added support for CRLF line endings as well as CR and LF. As well as the
613 default being selectable at build time, it can now be changed at runtime
614 via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
615 specify that it is scanning data with non-default line endings.
616
617 24. Changed the definition of CXXLINK to make it agree with the definition of
618 LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
619
620 25. Applied Ian Taylor's patches to avoid using another stack frame for tail
621 recursions. This makes a big different to stack usage for some patterns.
622
623 26. If a subpattern containing a named recursion or subroutine reference such
624 as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
625 the space required for the compiled pattern went wrong and gave too small a
626 value. Depending on the environment, this could lead to "Failed: internal
627 error: code overflow at offset 49" or "glibc detected double free or
628 corruption" errors.
629
630 27. Applied patches from Google (a) to support the new newline modes and (b) to
631 advance over multibyte UTF-8 characters in GlobalReplace.
632
633 28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
634 difference for some implementation of PCRE in some Windows version.
635
636 29. Added some extra testing facilities to pcretest:
637
638 \q<number> in a data line sets the "match limit" value
639 \Q<number> in a data line sets the "match recursion limt" value
640 -S <number> sets the stack size, where <number> is in megabytes
641
642 The -S option isn't available for Windows.
643
644
645 Version 6.6 06-Feb-06
646 ---------------------
647
648 1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
649 in pcreposix.h. I have copied the definition from pcre.h.
650
651 2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
652 because pcre.h is no longer a built file.
653
654 3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
655 not normally included in the compiled code.
656
657
658 Version 6.5 01-Feb-06
659 ---------------------
660
661 1. When using the partial match feature with pcre_dfa_exec(), it was not
662 anchoring the second and subsequent partial matches at the new starting
663 point. This could lead to incorrect results. For example, with the pattern
664 /1234/, partially matching against "123" and then "a4" gave a match.
665
666 2. Changes to pcregrep:
667
668 (a) All non-match returns from pcre_exec() were being treated as failures
669 to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
670 error message is output. Some extra information is given for the
671 PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
672 probably the only errors that are likely to be caused by users (by
673 specifying a regex that has nested indefinite repeats, for instance).
674 If there are more than 20 of these errors, pcregrep is abandoned.
675
676 (b) A binary zero was treated as data while matching, but terminated the
677 output line if it was written out. This has been fixed: binary zeroes
678 are now no different to any other data bytes.
679
680 (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
681 used to set a locale for matching. The --locale=xxxx long option has
682 been added (no short equivalent) to specify a locale explicitly on the
683 pcregrep command, overriding the environment variables.
684
685 (d) When -B was used with -n, some line numbers in the output were one less
686 than they should have been.
687
688 (e) Added the -o (--only-matching) option.
689
690 (f) If -A or -C was used with -c (count only), some lines of context were
691 accidentally printed for the final match.
692
693 (g) Added the -H (--with-filename) option.
694
695 (h) The combination of options -rh failed to suppress file names for files
696 that were found from directory arguments.
697
698 (i) Added the -D (--devices) and -d (--directories) options.
699
700 (j) Added the -F (--fixed-strings) option.
701
702 (k) Allow "-" to be used as a file name for -f as well as for a data file.
703
704 (l) Added the --colo(u)r option.
705
706 (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
707 is not present by default.
708
709 3. A nasty bug was discovered in the handling of recursive patterns, that is,
710 items such as (?R) or (?1), when the recursion could match a number of
711 alternatives. If it matched one of the alternatives, but subsequently,
712 outside the recursion, there was a failure, the code tried to back up into
713 the recursion. However, because of the way PCRE is implemented, this is not
714 possible, and the result was an incorrect result from the match.
715
716 In order to prevent this happening, the specification of recursion has
717 been changed so that all such subpatterns are automatically treated as
718 atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
719
720 4. I had overlooked the fact that, in some locales, there are characters for
721 which isalpha() is true but neither isupper() nor islower() are true. In
722 the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
723 and ordfeminine) are like this. This affected the treatment of \w and \W
724 when they appeared in character classes, but not when they appeared outside
725 a character class. The bit map for "word" characters is now created
726 separately from the results of isalnum() instead of just taking it from the
727 upper, lower, and digit maps. (Plus the underscore character, of course.)
728
729 5. The above bug also affected the handling of POSIX character classes such as
730 [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
731 permanent tables. Instead, the bit maps for such a class were previously
732 created as the appropriate unions of the upper, lower, and digit bitmaps.
733 Now they are created by subtraction from the [[:word:]] class, which has
734 its own bitmap.
735
736 6. The [[:blank:]] character class matches horizontal, but not vertical space.
737 It is created by subtracting the vertical space characters (\x09, \x0a,
738 \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
739 subtraction was done in the overall bitmap for a character class, meaning
740 that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
741 be recognized. This bug has been fixed.
742
743 7. Patches from the folks at Google:
744
745 (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
746 real life, but is still worth protecting against".
747
748 (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
749 regular expressions".
750
751 (c) pcre_scanner.cc: avoid use of std::count() because not all systems
752 have it.
753
754 (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
755 "configure" and the latter not, in order to fix a problem somebody had
756 with compiling the Arg class on HP-UX.
757
758 (e) Improve the error-handling of the C++ wrapper a little bit.
759
760 (f) New tests for checking recursion limiting.
761
762 8. The pcre_memmove() function, which is used only if the environment does not
763 have a standard memmove() function (and is therefore rarely compiled),
764 contained two bugs: (a) use of int instead of size_t, and (b) it was not
765 returning a result (though PCRE never actually uses the result).
766
767 9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
768 large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
769 returned instead of calling malloc() with an overflowing number that would
770 most likely cause subsequent chaos.
771
772 10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
773
774 11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
775 with this option is matched, the nmatch and pmatch options of regexec() are
776 ignored.
777
778 12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
779 provided in case anyone wants to the the POSIX interface with UTF-8
780 strings.
781
782 13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
783 C++ linking (needed for some HP-UX environments).
784
785 14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
786 (unused parameter) and in the pcre_printint() function (omitted "default"
787 switch label when the default is to do nothing).
788
789 15. Added some code to make it possible, when PCRE is compiled as a C++
790 library, to replace subject pointers for pcre_exec() with a smart pointer
791 class, thus making it possible to process discontinuous strings.
792
793 16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
794 much the same function. They were added by different people who were trying
795 to make PCRE easy to compile on non-Unix systems. It has been suggested
796 that PCRE_EXPORT be abolished now that there is more automatic apparatus
797 for compiling on Windows systems. I have therefore replaced it with
798 PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
799 defaults to "extern" for C or "extern C" for C++, which works fine on
800 Unix-like systems. It is now possible to override the value of PCRE_DATA_
801 SCOPE with something explicit in config.h. In addition:
802
803 (a) pcreposix.h still had just "extern" instead of either of these macros;
804 I have replaced it with PCRE_DATA_SCOPE.
805
806 (b) Functions such as _pcre_xclass(), which are internal to the library,
807 but external in the C sense, all had PCRE_EXPORT in their definitions.
808 This is apparently wrong for the Windows case, so I have removed it.
809 (It makes no difference on Unix-like systems.)
810
811 17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
812 of recursive calls to match(). This is different to MATCH_LIMIT because
813 that limits the total number of calls to match(), not all of which increase
814 the depth of recursion. Limiting the recursion depth limits the amount of
815 stack (or heap if NO_RECURSE is set) that is used. The default can be set
816 when PCRE is compiled, and changed at run time. A patch from Google adds
817 this functionality to the C++ interface.
818
819 18. Changes to the handling of Unicode character properties:
820
821 (a) Updated the table to Unicode 4.1.0.
822
823 (b) Recognize characters that are not in the table as "Cn" (undefined).
824
825 (c) I revised the way the table is implemented to a much improved format
826 which includes recognition of ranges. It now supports the ranges that
827 are defined in UnicodeData.txt, and it also amalgamates other
828 characters into ranges. This has reduced the number of entries in the
829 table from around 16,000 to around 3,000, thus reducing its size
830 considerably. I realized I did not need to use a tree structure after
831 all - a binary chop search is just as efficient. Having reduced the
832 number of entries, I extended their size from 6 bytes to 8 bytes to
833 allow for more data.
834
835 (d) Added support for Unicode script names via properties such as \p{Han}.
836
837 19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
838 matching that character.
839
840 20. When matching a repeated Unicode property with a minimum greater than zero,
841 (for example \pL{2,}), PCRE could look past the end of the subject if it
842 reached it while seeking the minimum number of characters. This could
843 happen only if some of the characters were more than one byte long, because
844 there is a check for at least the minimum number of bytes.
845
846 21. Refactored the implementation of \p and \P so as to be more general, to
847 allow for more different types of property in future. This has changed the
848 compiled form incompatibly. Anybody with saved compiled patterns that use
849 \p or \P will have to recompile them.
850
851 22. Added "Any" and "L&" to the supported property types.
852
853 23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
854 but give a compile time error if the value is greater than 0xff.
855
856 24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
857 accidentally not being installed or uninstalled.
858
859 25. The pcre.h file was built from pcre.h.in, but the only changes that were
860 made were to insert the current release number. This seemed silly, because
861 it made things harder for people building PCRE on systems that don't run
862 "configure". I have turned pcre.h into a distributed file, no longer built
863 by "configure", with the version identification directly included. There is
864 no longer a pcre.h.in file.
865
866 However, this change necessitated a change to the pcre-config script as
867 well. It is built from pcre-config.in, and one of the substitutions was the
868 release number. I have updated configure.ac so that ./configure now finds
869 the release number by grepping pcre.h.
870
871 26. Added the ability to run the tests under valgrind.
872
873
874 Version 6.4 05-Sep-05
875 ---------------------
876
877 1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
878 "--" to be printed when multiple files were scanned, even when none of the
879 -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
880 consider it to be a bug, and have restored the previous behaviour.
881
882 2. A couple of code tidies to get rid of compiler warnings.
883
884 3. The pcretest program used to cheat by referring to symbols in the library
885 whose names begin with _pcre_. These are internal symbols that are not
886 really supposed to be visible externally, and in some environments it is
887 possible to suppress them. The cheating is now confined to including
888 certain files from the library's source, which is a bit cleaner.
889
890 4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
891 file's purpose clearer.
892
893 5. Reorganized pcre_ucp_findchar().
894
895
896 Version 6.3 15-Aug-05
897 ---------------------
898
899 1. The file libpcre.pc.in did not have general read permission in the tarball.
900
901 2. There were some problems when building without C++ support:
902
903 (a) If C++ support was not built, "make install" and "make test" still
904 tried to test it.
905
906 (b) There were problems when the value of CXX was explicitly set. Some
907 changes have been made to try to fix these, and ...
908
909 (c) --disable-cpp can now be used to explicitly disable C++ support.
910
911 (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
912 backslash in a target when C++ was disabled. This confuses some
913 versions of "make", apparently. Using an intermediate variable solves
914 this. (Same for CPP_LOBJ.)
915
916 3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
917 (non-Windows) now includes $(CFLAGS) because these flags are sometimes
918 necessary on certain architectures.
919
920 4. Added a setting of -export-symbols-regex to the link command to remove
921 those symbols that are exported in the C sense, but actually are local
922 within the library, and not documented. Their names all begin with
923 "_pcre_". This is not a perfect job, because (a) we have to except some
924 symbols that pcretest ("illegally") uses, and (b) the facility isn't always
925 available (and never for static libraries). I have made a note to try to
926 find a way round (a) in the future.
927
928
929 Version 6.2 01-Aug-05
930 ---------------------
931
932 1. There was no test for integer overflow of quantifier values. A construction
933 such as {1111111111111111} would give undefined results. What is worse, if
934 a minimum quantifier for a parenthesized subpattern overflowed and became
935 negative, the calculation of the memory size went wrong. This could have
936 led to memory overwriting.
937
938 2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
939
940 3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
941 operating environments where this matters.
942
943 4. Applied Giuseppe Maxia's patch to add additional features for controlling
944 PCRE options from within the C++ wrapper.
945
946 5. Named capturing subpatterns were not being correctly counted when a pattern
947 was compiled. This caused two problems: (a) If there were more than 100
948 such subpatterns, the calculation of the memory needed for the whole
949 compiled pattern went wrong, leading to an overflow error. (b) Numerical
950 back references of the form \12, where the number was greater than 9, were
951 not recognized as back references, even though there were sufficient
952 previous subpatterns.
953
954 6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
955 versions of gcc, e.g. 2.95.4.
956
957
958 Version 6.1 21-Jun-05
959 ---------------------
960
961 1. There was one reference to the variable "posix" in pcretest.c that was not
962 surrounded by "#if !defined NOPOSIX".
963
964 2. Make it possible to compile pcretest without DFA support, UTF8 support, or
965 the cross-check on the old pcre_info() function, for the benefit of the
966 cut-down version of PCRE that is currently imported into Exim.
967
968 3. A (silly) pattern starting with (?i)(?-i) caused an internal space
969 allocation error. I've done the easy fix, which wastes 2 bytes for sensible
970 patterns that start (?i) but I don't think that matters. The use of (?i) is
971 just an example; this all applies to the other options as well.
972
973 4. Since libtool seems to echo the compile commands it is issuing, the output
974 from "make" can be reduced a bit by putting "@" in front of each libtool
975 compile command.
976
977 5. Patch from the folks at Google for configure.in to be a bit more thorough
978 in checking for a suitable C++ installation before trying to compile the
979 C++ stuff. This should fix a reported problem when a compiler was present,
980 but no suitable headers.
981
982 6. The man pages all had just "PCRE" as their title. I have changed them to
983 be the relevant file name. I have also arranged that these names are
984 retained in the file doc/pcre.txt, which is a concatenation in text format
985 of all the man pages except the little individual ones for each function.
986
987 7. The NON-UNIX-USE file had not been updated for the different set of source
988 files that come with release 6. I also added a few comments about the C++
989 wrapper.
990
991
992 Version 6.0 07-Jun-05
993 ---------------------
994
995 1. Some minor internal re-organization to help with my DFA experiments.
996
997 2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
998 didn't matter for the library itself when fully configured, but did matter
999 when compiling without UCP support, or within Exim, where the ucp files are
1000 not imported.
1001
1002 3. Refactoring of the library code to split up the various functions into
1003 different source modules. The addition of the new DFA matching code (see
1004 below) to a single monolithic source would have made it really too
1005 unwieldy, quite apart from causing all the code to be include in a
1006 statically linked application, when only some functions are used. This is
1007 relevant even without the DFA addition now that patterns can be compiled in
1008 one application and matched in another.
1009
1010 The downside of splitting up is that there have to be some external
1011 functions and data tables that are used internally in different modules of
1012 the library but which are not part of the API. These have all had their
1013 names changed to start with "_pcre_" so that they are unlikely to clash
1014 with other external names.
1015
1016 4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1017 a different (DFA) algorithm. Although it is slower than the original
1018 function, it does have some advantages for certain types of matching
1019 problem.
1020
1021 5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1022 including restarting after a partial match.
1023
1024 6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1025 defined when compiling for Windows was sent to me. I have put it into the
1026 code, though I have no means of testing or verifying it.
1027
1028 7. Added the pcre_refcount() auxiliary function.
1029
1030 8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1031 match before or at the first newline in the subject string. In pcretest,
1032 the /f option on a pattern can be used to set this.
1033
1034 9. A repeated \w when used in UTF-8 mode with characters greater than 256
1035 would behave wrongly. This has been present in PCRE since release 4.0.
1036
1037 10. A number of changes to the pcregrep command:
1038
1039 (a) Refactored how -x works; insert ^(...)$ instead of setting
1040 PCRE_ANCHORED and checking the length, in preparation for adding
1041 something similar for -w.
1042
1043 (b) Added the -w (match as a word) option.
1044
1045 (c) Refactored the way lines are read and buffered so as to have more
1046 than one at a time available.
1047
1048 (d) Implemented a pcregrep test script.
1049
1050 (e) Added the -M (multiline match) option. This allows patterns to match
1051 over several lines of the subject. The buffering ensures that at least
1052 8K, or the rest of the document (whichever is the shorter) is available
1053 for matching (and similarly the previous 8K for lookbehind assertions).
1054
1055 (f) Changed the --help output so that it now says
1056
1057 -w, --word-regex(p)
1058
1059 instead of two lines, one with "regex" and the other with "regexp"
1060 because that confused at least one person since the short forms are the
1061 same. (This required a bit of code, as the output is generated
1062 automatically from a table. It wasn't just a text change.)
1063
1064 (g) -- can be used to terminate pcregrep options if the next thing isn't an
1065 option but starts with a hyphen. Could be a pattern or a path name
1066 starting with a hyphen, for instance.
1067
1068 (h) "-" can be given as a file name to represent stdin.
1069
1070 (i) When file names are being printed, "(standard input)" is used for
1071 the standard input, for compatibility with GNU grep. Previously
1072 "<stdin>" was used.
1073
1074 (j) The option --label=xxx can be used to supply a name to be used for
1075 stdin when file names are being printed. There is no short form.
1076
1077 (k) Re-factored the options decoding logic because we are going to add
1078 two more options that take data. Such options can now be given in four
1079 different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1080
1081 (l) Added the -A, -B, and -C options for requesting that lines of context
1082 around matches be printed.
1083
1084 (m) Added the -L option to print the names of files that do not contain
1085 any matching lines, that is, the complement of -l.
1086
1087 (n) The return code is 2 if any file cannot be opened, but pcregrep does
1088 continue to scan other files.
1089
1090 (o) The -s option was incorrectly implemented. For compatibility with other
1091 greps, it now suppresses the error message for a non-existent or non-
1092 accessible file (but not the return code). There is a new option called
1093 -q that suppresses the output of matching lines, which was what -s was
1094 previously doing.
1095
1096 (p) Added --include and --exclude options to specify files for inclusion
1097 and exclusion when recursing.
1098
1099 11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1100 Hopefully, it now does.
1101
1102 12. Missing cast in pcre_study().
1103
1104 13. Added an "uninstall" target to the makefile.
1105
1106 14. Replaced "extern" in the function prototypes in Makefile.in with
1107 "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1108 world, but is set differently for Windows.
1109
1110 15. Added a second compiling function called pcre_compile2(). The only
1111 difference is that it has an extra argument, which is a pointer to an
1112 integer error code. When there is a compile-time failure, this is set
1113 non-zero, in addition to the error test pointer being set to point to an
1114 error message. The new argument may be NULL if no error number is required
1115 (but then you may as well call pcre_compile(), which is now just a
1116 wrapper). This facility is provided because some applications need a
1117 numeric error indication, but it has also enabled me to tidy up the way
1118 compile-time errors are handled in the POSIX wrapper.
1119
1120 16. Added VPATH=.libs to the makefile; this should help when building with one
1121 prefix path and installing with another. (Or so I'm told by someone who
1122 knows more about this stuff than I do.)
1123
1124 17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1125 passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1126 match everything, including newlines. This is not POSIX-compatible, but
1127 somebody wanted the feature. From pcretest it can be activated by using
1128 both the P and the s flags.
1129
1130 18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1131
1132 19. libpcre.pc was being incorrectly installed as executable.
1133
1134 20. A couple of places in pcretest check for end-of-line by looking for '\n';
1135 it now also looks for '\r' so that it will work unmodified on Windows.
1136
1137 21. Added Google's contributed C++ wrapper to the distribution.
1138
1139 22. Added some untidy missing memory free() calls in pcretest, to keep
1140 Electric Fence happy when testing.
1141
1142
1143
1144 Version 5.0 13-Sep-04
1145 ---------------------
1146
1147 1. Internal change: literal characters are no longer packed up into items
1148 containing multiple characters in a single byte-string. Each character
1149 is now matched using a separate opcode. However, there may be more than one
1150 byte in the character in UTF-8 mode.
1151
1152 2. The pcre_callout_block structure has two new fields: pattern_position and
1153 next_item_length. These contain the offset in the pattern to the next match
1154 item, and its length, respectively.
1155
1156 3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1157 insertion of callouts before each pattern item. Added the /C option to
1158 pcretest to make use of this.
1159
1160 4. On the advice of a Windows user, the lines
1161
1162 #if defined(_WIN32) || defined(WIN32)
1163 _setmode( _fileno( stdout ), 0x8000 );
1164 #endif /* defined(_WIN32) || defined(WIN32) */
1165
1166 have been added to the source of pcretest. This apparently does useful
1167 magic in relation to line terminators.
1168
1169 5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1170 for the benefit of those environments where the "b" makes a difference.
1171
1172 6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1173 to know about it. I have put a hack into configure.in that adds in code
1174 to set GCC=yes if CC=icc. This seems to end up at a point in the
1175 generated configure script that is early enough to affect the setting of
1176 compiler options, which is what is needed, but I have no means of testing
1177 whether it really works. (The user who reported this had patched the
1178 generated configure script, which of course I cannot do.)
1179
1180 LATER: After change 22 below (new libtool files), the configure script
1181 seems to know about icc (and also ecc). Therefore, I have commented out
1182 this hack in configure.in.
1183
1184 7. Added support for pkg-config (2 patches were sent in).
1185
1186 8. Negated POSIX character classes that used a combination of internal tables
1187 were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1188 [[:^ascii]]. Typically, they would match almost any characters. The other
1189 POSIX classes were not broken in this way.
1190
1191 9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1192 to find the match, as PCRE was deluded into thinking that the match had to
1193 start at the start point or following a newline. The same bug applied to
1194 patterns with negative forward assertions or any backward assertions
1195 preceding ".*" at the start, unless the pattern required a fixed first
1196 character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1197
1198 10. In UTF-8 mode, when moving forwards in the subject after a failed match
1199 starting at the last subject character, bytes beyond the end of the subject
1200 string were read.
1201
1202 11. Renamed the variable "class" as "classbits" to make life easier for C++
1203 users. (Previously there was a macro definition, but it apparently wasn't
1204 enough.)
1205
1206 12. Added the new field "tables" to the extra data so that tables can be passed
1207 in at exec time, or the internal tables can be re-selected. This allows
1208 a compiled regex to be saved and re-used at a later time by a different
1209 program that might have everything at different addresses.
1210
1211 13. Modified the pcre-config script so that, when run on Solaris, it shows a
1212 -R library as well as a -L library.
1213
1214 14. The debugging options of pcretest (-d on the command line or D on a
1215 pattern) showed incorrect output for anything following an extended class
1216 that contained multibyte characters and which was followed by a quantifier.
1217
1218 15. Added optional support for general category Unicode character properties
1219 via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1220 support. It adds about 90K to the size of the library. The meanings of the
1221 inbuilt class escapes such as \d and \s have NOT been changed.
1222
1223 16. Updated pcredemo.c to include calls to free() to release the memory for the
1224 compiled pattern.
1225
1226 17. The generated file chartables.c was being created in the source directory
1227 instead of in the building directory. This caused the build to fail if the
1228 source directory was different from the building directory, and was
1229 read-only.
1230
1231 18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1232 file. No doubt somebody will tell me if they don't make sense... Also added
1233 Dan Mooney's comments about building on OpenVMS.
1234
1235 19. Added support for partial matching via the PCRE_PARTIAL option for
1236 pcre_exec() and the \P data escape in pcretest.
1237
1238 20. Extended pcretest with 3 new pattern features:
1239
1240 (i) A pattern option of the form ">rest-of-line" causes pcretest to
1241 write the compiled pattern to the file whose name is "rest-of-line".
1242 This is a straight binary dump of the data, with the saved pointer to
1243 the character tables forced to be NULL. The study data, if any, is
1244 written too. After writing, pcretest reads a new pattern.
1245
1246 (ii) If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1247 compiled pattern from the given file. There must not be any
1248 occurrences of "<" in the file name (pretty unlikely); if there are,
1249 pcretest will instead treat the initial "<" as a pattern delimiter.
1250 After reading in the pattern, pcretest goes on to read data lines as
1251 usual.
1252
1253 (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1254 and 16-bit fields in a compiled pattern, to simulate a pattern that
1255 was compiled on a host of opposite endianness.
1256
1257 21. The pcre-exec() function can now cope with patterns that were compiled on
1258 hosts of opposite endianness, with this restriction:
1259
1260 As for any compiled expression that is saved and used later, the tables
1261 pointer field cannot be preserved; the extra_data field in the arguments
1262 to pcre_exec() should be used to pass in a tables address if a value
1263 other than the default internal tables were used at compile time.
1264
1265 22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1266 now diagnosed as an error. Previously, most of the time, a negative number
1267 would have been treated as zero, but if in addition "ovector" was passed as
1268 NULL, a crash could occur.
1269
1270 23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1271 new versions from the libtool 1.5 distribution (the last one is a copy of
1272 a file called libtool.m4). This seems to have fixed the need to patch
1273 "configure" to support Darwin 1.3 (which I used to do). However, I still
1274 had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1275 workstation).
1276
1277 24. Changed the PCRE licence to be the more standard "BSD" licence.
1278
1279
1280 Version 4.5 01-Dec-03
1281 ---------------------
1282
1283 1. There has been some re-arrangement of the code for the match() function so
1284 that it can be compiled in a version that does not call itself recursively.
1285 Instead, it keeps those local variables that need separate instances for
1286 each "recursion" in a frame on the heap, and gets/frees frames whenever it
1287 needs to "recurse". Keeping track of where control must go is done by means
1288 of setjmp/longjmp. The whole thing is implemented by a set of macros that
1289 hide most of the details from the main code, and operates only if
1290 NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1291 "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1292 operating.
1293
1294 To make it easier for callers to provide specially tailored get/free
1295 functions for this usage, two new functions, pcre_stack_malloc, and
1296 pcre_stack_free, are used. They are always called in strict stacking order,
1297 and the size of block requested is always the same.
1298
1299 The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1300 PCRE has been compiled to use the stack or the heap for recursion. The
1301 -C option of pcretest uses this to show which version is compiled.
1302
1303 A new data escape \S, is added to pcretest; it causes the amounts of store
1304 obtained and freed by both kinds of malloc/free at match time to be added
1305 to the output.
1306
1307 2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1308 what's available on my current Linux desktop machine.
1309
1310 3. When matching a UTF-8 string, the test for a valid string at the start has
1311 been extended. If start_offset is not zero, PCRE now checks that it points
1312 to a byte that is the start of a UTF-8 character. If not, it returns
1313 PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1314 this is necessary because there may be backward assertions in the pattern.
1315 When matching the same subject several times, it may save resources to use
1316 PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1317
1318 4. The code for checking the validity of UTF-8 strings has been tightened so
1319 that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1320 containing "overlong sequences".
1321
1322 5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1323 I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1324 should have been "&", but it just so happened that all the cases this let
1325 through by mistake were picked up later in the function.
1326
1327 6. I had used a variable called "isblank" - this is a C99 function, causing
1328 some compilers to warn. To avoid this, I renamed it (as "blankclass").
1329
1330 7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1331 prompting; (b) run "./pcretest /dev/null" at the start of the test script
1332 so the version is shown; (c) stop "make test" echoing "./RunTest".
1333
1334 8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1335
1336 9. The prototype for memmove() for systems that don't have it was using
1337 size_t, but the inclusion of the header that defines size_t was later. I've
1338 moved the #includes for the C headers earlier to avoid this.
1339
1340 10. Added some adjustments to the code to make it easier to compiler on certain
1341 special systems:
1342
1343 (a) Some "const" qualifiers were missing.
1344 (b) Added the macro EXPORT before all exported functions; by default this
1345 is defined to be empty.
1346 (c) Changed the dftables auxiliary program (that builds chartables.c) so
1347 that it reads its output file name as an argument instead of writing
1348 to the standard output and assuming this can be redirected.
1349
1350 11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1351 class containing characters with values greater than 255, PCRE compilation
1352 went into a loop.
1353
1354 12. A recursive reference to a subpattern that was within another subpattern
1355 that had a minimum quantifier of zero caused PCRE to crash. For example,
1356 (x(y(?2))z)? provoked this bug with a subject that got as far as the
1357 recursion. If the recursively-called subpattern itself had a zero repeat,
1358 that was OK.
1359
1360 13. In pcretest, the buffer for reading a data line was set at 30K, but the
1361 buffer into which it was copied (for escape processing) was still set at
1362 1024, so long lines caused crashes.
1363
1364 14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1365 "internal error: code overflow...". This applied to any character class
1366 that was followed by a possessive quantifier.
1367
1368 15. Modified the Makefile to add libpcre.la as a prerequisite for
1369 libpcreposix.la because I was told this is needed for a parallel build to
1370 work.
1371
1372 16. If a pattern that contained .* following optional items at the start was
1373 studied, the wrong optimizing data was generated, leading to matching
1374 errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1375 matching string must start with a or b or c. The correct conclusion for
1376 this pattern is that a match can start with any character.
1377
1378
1379 Version 4.4 13-Aug-03
1380 ---------------------
1381
1382 1. In UTF-8 mode, a character class containing characters with values between
1383 127 and 255 was not handled correctly if the compiled pattern was studied.
1384 In fixing this, I have also improved the studying algorithm for such
1385 classes (slightly).
1386
1387 2. Three internal functions had redundant arguments passed to them. Removal
1388 might give a very teeny performance improvement.
1389
1390 3. Documentation bug: the value of the capture_top field in a callout is *one
1391 more than* the number of the hightest numbered captured substring.
1392
1393 4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1394 in incorrectly linking with a previously installed version. They now link
1395 explicitly with libpcre.la.
1396
1397 5. configure.in no longer needs to recognize Cygwin specially.
1398
1399 6. A problem in pcre.in for Windows platforms is fixed.
1400
1401 7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1402 pcretest, it used to include the size of the study block as part of its
1403 output. Unfortunately, the structure contains a field that has a different
1404 size on different hardware architectures. This meant that the tests that
1405 showed this size failed. As the block is currently always of a fixed size,
1406 this information isn't actually particularly useful in pcretest output, so
1407 I have just removed it.
1408
1409 8. Three pre-processor statements accidentally did not start in column 1.
1410 Sadly, there are *still* compilers around that complain, even though
1411 standard C has not required this for well over a decade. Sigh.
1412
1413 9. In pcretest, the code for checking callouts passed small integers in the
1414 callout_data field, which is a void * field. However, some picky compilers
1415 complained about the casts involved for this on 64-bit systems. Now
1416 pcretest passes the address of the small integer instead, which should get
1417 rid of the warnings.
1418
1419 10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1420 both compile and run time, and gives an error if an invalid UTF-8 sequence
1421 is found. There is a option for disabling this check in cases where the
1422 string is known to be correct and/or the maximum performance is wanted.
1423
1424 11. In response to a bug report, I changed one line in Makefile.in from
1425
1426 -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1427 to
1428 -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1429
1430 to look similar to other lines, but I have no way of telling whether this
1431 is the right thing to do, as I do not use Windows. No doubt I'll get told
1432 if it's wrong...
1433
1434
1435 Version 4.3 21-May-03
1436 ---------------------
1437
1438 1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1439 Makefile.
1440
1441 2. Some refactoring to improve the quality of the code:
1442
1443 (i) The utf8_table... variables are now declared "const".
1444
1445 (ii) The code for \cx, which used the "case flipping" table to upper case
1446 lower case letters, now just substracts 32. This is ASCII-specific,
1447 but the whole concept of \cx is ASCII-specific, so it seems
1448 reasonable.
1449
1450 (iii) PCRE was using its character types table to recognize decimal and
1451 hexadecimal digits in the pattern. This is silly, because it handles
1452 only 0-9, a-f, and A-F, but the character types table is locale-
1453 specific, which means strange things might happen. A private
1454 table is now used for this - though it costs 256 bytes, a table is
1455 much faster than multiple explicit tests. Of course, the standard
1456 character types table is still used for matching digits in subject
1457 strings against \d.
1458
1459 (iv) Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1460 ending in _t are). So I've renamed it as ESC_tee.
1461
1462 3. The first argument for regexec() in the POSIX wrapper should have been
1463 defined as "const".
1464
1465 4. Changed pcretest to use malloc() for its buffers so that they can be
1466 Electric Fenced for debugging.
1467
1468 5. There were several places in the code where, in UTF-8 mode, PCRE would try
1469 to read one or more bytes before the start of the subject string. Often this
1470 had no effect on PCRE's behaviour, but in some circumstances it could
1471 provoke a segmentation fault.
1472
1473 6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1474 to try to read one or more bytes before the start of the subject string.
1475
1476 7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1477 UTF-8 support could misbehave in various ways if the subject string
1478 contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1479 area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1480 back over UTF-8 characters.)
1481
1482
1483 Version 4.2 14-Apr-03
1484 ---------------------
1485
1486 1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1487
1488 2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1489 [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1490 [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1491 [WIN_PREFIX]: new variable, "cyg" for Cygwin
1492 * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1493 and BUILD_EXEEXT
1494 Note: automatic setting of the BUILD variables is not yet working
1495 set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1496 compile-time but not at link-time
1497 [LINK]: use for linking executables only
1498 make different versions for Windows and non-Windows
1499 [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1500 libraries
1501 [LINK_FOR_BUILD]: new variable
1502 [OBJEXT]: use throughout
1503 [EXEEXT]: use throughout
1504 <winshared>: new target
1505 <wininstall>: new target
1506 <dftables.o>: use native compiler
1507 <dftables>: use native linker
1508 <install>: handle Windows platform correctly
1509 <clean>: ditto
1510 <check>: ditto
1511 copy DLL to top builddir before testing
1512
1513 As part of these changes, -no-undefined was removed again. This was reported
1514 to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1515 in any case.
1516
1517 3. Some tidies to get rid of compiler warnings:
1518
1519 . In the match_data structure, match_limit was an unsigned long int, whereas
1520 match_call_count was an int. I've made them both unsigned long ints.
1521
1522 . In pcretest the fact that a const uschar * doesn't automatically cast to
1523 a void * provoked a warning.
1524
1525 . Turning on some more compiler warnings threw up some "shadow" variables
1526 and a few more missing casts.
1527
1528 4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1529 option, a class that contained a single character with a value between 128
1530 and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1531
1532 5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1533 option, a class that contained several characters, but with at least one
1534 whose value was between 128 and 255 caused PCRE to crash.
1535
1536
1537 Version 4.1 12-Mar-03
1538 ---------------------
1539
1540 1. Compiling with gcc -pedantic found a couple of places where casts were
1541 needed, and a string in dftables.c that was longer than standard compilers are
1542 required to support.
1543
1544 2. Compiling with Sun's compiler found a few more places where the code could
1545 be tidied up in order to avoid warnings.
1546
1547 3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1548 first of these names is deprecated in the latest Autoconf in favour of the name
1549 CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1550 compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1551 analogy I have changed it to CFLAGS_FOR_BUILD.
1552
1553 4. Added -no-undefined to the linking command in the Makefile, because this is
1554 apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1555 linking step for the pcreposix library.
1556
1557 5. PCRE was failing to diagnose the case of two named groups with the same
1558 name.
1559
1560 6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1561 literal character that is needed in the subject for a match, and scans along to
1562 ensure that it is present before embarking on the full matching process. This
1563 saves time in cases of nested unlimited repeats that are never going to match.
1564 Problem: the scan can take a lot of time if the subject is very long (e.g.
1565 megabytes), thus penalizing straightforward matches. It is now done only if the
1566 amount of subject to be scanned is less than 1000 bytes.
1567
1568 7. A lesser problem with the same optimization is that it was recording the
1569 first character of an anchored pattern as "needed", thus provoking a search
1570 right along the subject, even when the first match of the pattern was going to
1571 fail. The "needed" character is now not set for anchored patterns, unless it
1572 follows something in the pattern that is of non-fixed length. Thus, it still
1573 fulfils its original purpose of finding quick non-matches in cases of nested
1574 unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1575
1576
1577 Version 4.0 17-Feb-03
1578 ---------------------
1579
1580 1. If a comment in an extended regex that started immediately after a meta-item
1581 extended to the end of string, PCRE compiled incorrect data. This could lead to
1582 all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1583
1584 2. Moved to autoconf 2.53 and libtool 1.4.2.
1585
1586 3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1587 the special perltest8 script is no longer needed - all the tests can be run
1588 from a single perltest script.
1589
1590 4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1591 by \s. It has now been removed in PCRE. This means it isn't recognized as
1592 whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1593 class [:space:] *does* include VT, thereby creating a mess.
1594
1595 5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1596 space and tab.
1597
1598 6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1599 its new features into the main test script, reducing the number of scripts.
1600
1601 7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1602 were backward compatible, and made the (?i) apply to the whole pattern, as if
1603 /i were given. Now it behaves more logically, and applies the option setting
1604 only to what follows. PCRE has been changed to follow suit. However, if it
1605 finds options settings right at the start of the pattern, it extracts them into
1606 the global options, as before. Thus, they show up in the info data.
1607
1608 8. Added support for the \Q...\E escape sequence. Characters in between are
1609 treated as literals. This is slightly different from Perl in that $ and @ are
1610 also handled as literals inside the quotes. In Perl, they will cause variable
1611 interpolation. Note the following examples:
1612
1613 Pattern PCRE matches Perl matches
1614
1615 \Qabc$xyz\E abc$xyz abc followed by the contents of $xyz
1616 \Qabc\$xyz\E abc\$xyz abc\$xyz
1617 \Qabc\E\$\Qxyz\E abc$xyz abc$xyz
1618
1619 For compatibility with Perl, \Q...\E sequences are recognized inside character
1620 classes as well as outside them.
1621
1622 9. Re-organized 3 code statements in pcretest to avoid "overflow in
1623 floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1624 (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1625 signed/unsigned warnings.
1626
1627 10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1628 option for pcretest, so I've replaced it by a simple function that does just
1629 that job.
1630
1631 11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1632 "pcregrep -".
1633
1634 12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1635 Java package. This provides some syntactic sugar for simple cases of what my
1636 documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1637 as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1638 item, you can use this simplified notation. Note that only makes sense with
1639 greedy quantifiers. Consequently, the use of the possessive quantifier forces
1640 greediness, whatever the setting of the PCRE_UNGREEDY option.
1641
1642 13. A change of greediness default within a pattern was not taking effect at
1643 the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1644 subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1645 was abstracted outside.
1646
1647 14. PCRE now supports the \G assertion. It is true when the current matching
1648 position is at the start point of the match. This differs from \A when the
1649 starting offset is non-zero. Used with the /g option of pcretest (or similar
1650 code), it works in the same way as it does for Perl's /g option. If all
1651 alternatives of a regex begin with \G, the expression is anchored to the start
1652 match position, and the "anchored" flag is set in the compiled expression.
1653
1654 15. Some bugs concerning the handling of certain option changes within patterns
1655 have been fixed. These applied to options other than (?ims). For example,
1656 "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1657 been the other way round. Some of this was related to change 7 above.
1658
1659 16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1660 features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1661 and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1662 POSIX classes only within a class (e.g. /[[:alpha:]]/).
1663
1664 17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1665 mode. Unlike ".", it always matches newline, whatever the setting of
1666 PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1667 assertions. Perl allows it, but it doesn't (in general) work because it can't
1668 calculate the length of the lookbehind. At least, that's the case for Perl
1669 5.8.0 - I've been told they are going to document that it doesn't work in
1670 future.
1671
1672 18. Added an error diagnosis for escapes that PCRE does not support: these are
1673 \L, \l, \N, \P, \p, \U, \u, and \X.
1674
1675 19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1676 reading past the end of the pattern in cases such as /[abcd/.
1677
1678 20. PCRE was getting more memory than necessary for patterns with classes that
1679 contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1680
1681 21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1682 compiling PCRE for use with Virtual Pascal.
1683
1684 22. Small fix to the Makefile to make it work properly if the build is done
1685 outside the source tree.
1686
1687 23. Added a new extension: a condition to go with recursion. If a conditional
1688 subpattern starts with (?(R) the "true" branch is used if recursion has
1689 happened, whereas the "false" branch is used only at the top level.
1690
1691 24. When there was a very long string of literal characters (over 255 bytes
1692 without UTF support, over 250 bytes with UTF support), the computation of how
1693 much memory was required could be incorrect, leading to segfaults or other
1694 strange effects.
1695
1696 25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1697 start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1698 there was a subsequent back reference to those brackets. This meant that, for
1699 example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1700 possible to check for precisely this case. All we can do is abandon the
1701 optimization if .* occurs inside capturing brackets when there are any back
1702 references whatsoever. (See below for a better fix that came later.)
1703
1704 26. The handling of the optimization for finding the first character of a
1705 non-anchored pattern, and for finding a character that is required later in the
1706 match were failing in some cases. This didn't break the matching; it just
1707 failed to optimize when it could. The way this is done has been re-implemented.
1708
1709 27. Fixed typo in error message for invalid (?R item (it said "(?p").
1710
1711 28. Added a new feature that provides some of the functionality that Perl
1712 provides with (?{...}). The facility is termed a "callout". The way it is done
1713 in PCRE is for the caller to provide an optional function, by setting
1714 pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1715 global variable. By default it is unset, which disables all calling out. To get
1716 the function called, the regex must include (?C) at appropriate points. This
1717 is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1718 This provides a means of identifying different callout points. When PCRE
1719 reaches such a point in the regex, if pcre_callout has been set, the external
1720 function is called. It is provided with data in a structure called
1721 pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1722 matching continues; if it returns a non-zero value, the match at the current
1723 point fails. However, backtracking will occur if possible. [This was changed
1724 later and other features added - see item 49 below.]
1725
1726 29. pcretest is upgraded to test the callout functionality. It provides a
1727 callout function that displays information. By default, it shows the start of
1728 the match and the current position in the text. There are some new data escapes
1729 to vary what happens:
1730
1731 \C+ in addition, show current contents of captured substrings
1732 \C- do not supply a callout function
1733 \C!n return 1 when callout number n is reached
1734 \C!n!m return 1 when callout number n is reached for the mth time
1735
1736 30. If pcregrep was called with the -l option and just a single file name, it
1737 output "<stdin>" if a match was found, instead of the file name.
1738
1739 31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1740 slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1741 pcre_exec(). This saves a malloc/free per call. The default value of
1742 POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1743 when configuring.
1744
1745 32. The default maximum size of a compiled pattern is 64K. There have been a
1746 few cases of people hitting this limit. The code now uses macros to handle the
1747 storing of links as offsets within the compiled pattern. It defaults to 2-byte
1748 links, but this can be changed to 3 or 4 bytes by --with-link-size when
1749 configuring. Tests 2 and 5 work only with 2-byte links because they output
1750 debugging information about compiled patterns.
1751
1752 33. Internal code re-arrangements:
1753
1754 (a) Moved the debugging function for printing out a compiled regex into
1755 its own source file (printint.c) and used #include to pull it into
1756 pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1757 separate copies.
1758
1759 (b) Defined the list of op-code names for debugging as a macro in
1760 internal.h so that it is next to the definition of the opcodes.
1761
1762 (c) Defined a table of op-code lengths for simpler skipping along compiled
1763 code. This is again a macro in internal.h so that it is next to the
1764 definition of the opcodes.
1765
1766 34. Added support for recursive calls to individual subpatterns, along the
1767 lines of Robin Houston's patch (but implemented somewhat differently).
1768
1769 35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1770 allow it to read and process whole directories in Win32. This code was
1771 contributed by Lionel Fourquaux; it has not been tested by me.
1772
1773 36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1774 used to name a group. Names consist of alphanumerics and underscores, and must
1775 be unique. Back references use the syntax (?P=name) and recursive calls use
1776 (?P>name) which is a PCRE extension to the Python extension. Groups still have
1777 numbers. The function pcre_fullinfo() can be used after compilation to extract
1778 a name/number map. There are three relevant calls:
1779
1780 PCRE_INFO_NAMEENTRYSIZE yields the size of each entry in the map
1781 PCRE_INFO_NAMECOUNT yields the number of entries
1782 PCRE_INFO_NAMETABLE yields a pointer to the map.
1783
1784 The map is a vector of fixed-size entries. The size of each entry depends on
1785 the length of the longest name used. The first two bytes of each entry are the
1786 group number, most significant byte first. There follows the corresponding
1787 name, zero terminated. The names are in alphabetical order.
1788
1789 37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1790 case instead of 255. Making it the same both with and without UTF-8 support
1791 means that the same test output works with both.
1792
1793 38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1794 calling malloc() with a zero argument.
1795
1796 39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1797 optimization. I've improved things by keeping a bitmap of backreferences with
1798 numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1799 fact referenced, the optimization can be applied. It is unlikely that a
1800 relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1801 the match to follow \n) will appear inside brackets with a number greater than
1802 31, but if it does, any back reference > 31 suppresses the optimization.
1803
1804 40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1805 of disabling numbered capturing parentheses. Any opening parenthesis that is
1806 not followed by ? behaves as if it were followed by ?: but named parentheses
1807 can still be used for capturing (and they will acquire numbers in the usual
1808 way).
1809
1810 41. Redesigned the return codes from the match() function into yes/no/error so
1811 that errors can be passed back from deep inside the nested calls. A malloc
1812 failure while inside a recursive subpattern call now causes the
1813 PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1814
1815 42. It is now possible to set a limit on the number of times the match()
1816 function is called in a call to pcre_exec(). This facility makes it possible to
1817 limit the amount of recursion and backtracking, though not in a directly
1818 obvious way, because the match() function is used in a number of different
1819 circumstances. The count starts from zero for each position in the subject
1820 string (for non-anchored patterns). The default limit is, for compatibility, a
1821 large number, namely 10 000 000. You can change this in two ways:
1822
1823 (a) When configuring PCRE before making, you can use --with-match-limit=n
1824 to set a default value for the compiled library.
1825
1826 (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1827 a different value is set. See 45 below.
1828
1829 If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1830
1831 43. Added a new function pcre_config(int, void *) to enable run-time extraction
1832 of things that can be changed at compile time. The first argument specifies
1833 what is wanted and the second points to where the information is to be placed.
1834 The current list of available information is:
1835
1836 PCRE_CONFIG_UTF8
1837
1838 The output is an integer that is set to one if UTF-8 support is available;
1839 otherwise it is set to zero.
1840
1841 PCRE_CONFIG_NEWLINE
1842
1843 The output is an integer that it set to the value of the code that is used for
1844 newline. It is either LF (10) or CR (13).
1845
1846 PCRE_CONFIG_LINK_SIZE
1847
1848 The output is an integer that contains the number of bytes used for internal
1849 linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1850
1851 PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1852
1853 The output is an integer that contains the threshold above which the POSIX
1854 interface uses malloc() for output vectors. See item 31 above.
1855
1856 PCRE_CONFIG_MATCH_LIMIT
1857
1858 The output is an unsigned integer that contains the default limit of the number
1859 of match() calls in a pcre_exec() execution. See 42 above.
1860
1861 44. pcretest has been upgraded by the addition of the -C option. This causes it
1862 to extract all the available output from the new pcre_config() function, and to
1863 output it. The program then exits immediately.
1864
1865 45. A need has arisen to pass over additional data with calls to pcre_exec() in
1866 order to support additional features. One way would have been to define
1867 pcre_exec2() (for example) with extra arguments, but this would not have been
1868 extensible, and would also have required all calls to the original function to
1869 be mapped to the new one. Instead, I have chosen to extend the mechanism that
1870 is used for passing in "extra" data from pcre_study().
1871
1872 The pcre_extra structure is now exposed and defined in pcre.h. It currently
1873 contains the following fields:
1874
1875 flags a bitmap indicating which of the following fields are set
1876 study_data opaque data from pcre_study()
1877 match_limit a way of specifying a limit on match() calls for a specific
1878 call to pcre_exec()
1879 callout_data data for callouts (see 49 below)
1880
1881 The flag bits are also defined in pcre.h, and are
1882
1883 PCRE_EXTRA_STUDY_DATA
1884 PCRE_EXTRA_MATCH_LIMIT
1885 PCRE_EXTRA_CALLOUT_DATA
1886
1887 The pcre_study() function now returns one of these new pcre_extra blocks, with
1888 the actual study data pointed to by the study_data field, and the
1889 PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1890 before. That is, this change is entirely upwards-compatible and requires no
1891 change to existing code.
1892
1893 If you want to pass in additional data to pcre_exec(), you can either place it
1894 in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1895 block.
1896
1897 46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1898 data string contains the escape sequence \M, pcretest calls pcre_exec() several
1899 times with different match limits, until it finds the minimum value needed for
1900 pcre_exec() to complete. The value is then output. This can be instructive; for
1901 most simple matches the number is quite small, but for pathological cases it
1902 gets very large very quickly.
1903
1904 47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1905 returns the size of the data block pointed to by the study_data field in a
1906 pcre_extra block, that is, the value that was passed as the argument to
1907 pcre_malloc() when PCRE was getting memory in which to place the information
1908 created by pcre_study(). The fourth argument should point to a size_t variable.
1909 pcretest has been extended so that this information is shown after a successful
1910 pcre_study() call when information about the compiled regex is being displayed.
1911
1912 48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1913 because what follows is always an absolute path. (Later: it turns out that this
1914 is more than cosmetic for MinGW, because it doesn't like empty path
1915 components.)
1916
1917 49. Some changes have been made to the callout feature (see 28 above):
1918
1919 (i) A callout function now has three choices for what it returns:
1920
1921 0 => success, carry on matching
1922 > 0 => failure at this point, but backtrack if possible
1923 < 0 => serious error, return this value from pcre_exec()
1924
1925 Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1926 values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1927 "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1928 use by callout functions. It will never be used by PCRE itself.
1929
1930 (ii) The pcre_extra structure (see 45 above) has a void * field called
1931 callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1932 pcre_callout_block structure has a field of the same name. The contents of
1933 the field passed in the pcre_extra structure are passed to the callout
1934 function in the corresponding field in the callout block. This makes it
1935 easier to use the same callout-containing regex from multiple threads. For
1936 testing, the pcretest program has a new data escape
1937
1938 \C*n pass the number n (may be negative) as callout_data
1939
1940 If the callout function in pcretest receives a non-zero value as
1941 callout_data, it returns that value.
1942
1943 50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1944 there were some redundant $(CFLAGS) in commands that are now specified as
1945 $(LINK), which already includes $(CFLAGS).
1946
1947 51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1948 has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1949 with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1950 one-byte characters throughout. Note that case-insensitive matching applies
1951 only to characters whose values are less than 256. PCRE doesn't support the
1952 notion of cases for higher-valued characters.
1953
1954 (i) A character class whose characters are all within 0-255 is handled as
1955 a bit map, and the map is inverted for negative classes. Previously, a
1956 character > 255 always failed to match such a class; however it should
1957 match if the class was a negative one (e.g. [^ab]). This has been fixed.
1958
1959 (ii) A negated character class with a single character < 255 is coded as
1960 "not this character" (OP_NOT). This wasn't working properly when the test
1961 character was multibyte, either singly or repeated.
1962
1963 (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1964 mode, for example: \x{100}{2,3}.
1965
1966 (iv) The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1967 singly or repeated) now correctly test multibyte characters. However,
1968 PCRE doesn't recognize any characters with values greater than 255 as
1969 digits, spaces, or word characters. Such characters always match \D, \S,
1970 and \W, and never match \d, \s, or \w.
1971
1972 (v) Classes may now contain characters and character ranges with values
1973 greater than 255. For example: [ab\x{100}-\x{400}].
1974
1975 (vi) pcregrep now has a --utf-8 option (synonym -u) which makes it call
1976 PCRE in UTF-8 mode.
1977
1978 52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1979 PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1980 retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1981 value.)
1982
1983 53. The single man page has become too large. I have therefore split it up into
1984 a number of separate man pages. These also give rise to individual HTML pages;
1985 these are now put in a separate directory, and there is an index.html page that
1986 lists them all. Some hyperlinking between the pages has been installed.
1987
1988 54. Added convenience functions for handling named capturing parentheses.
1989
1990 55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1991 aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1992 true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1993 are faulted.
1994
1995 56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1996 calling configure. These values are used when compiling the dftables.c program
1997 which is run to generate the source of the default character tables. They
1998 default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1999 you will need to set these values.
2000
2001 57. Updated the building process for Windows DLL, as provided by Fred Cox.
2002
2003
2004 Version 3.9 02-Jan-02
2005 ---------------------
2006
2007 1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2008
2009 2. If --disable-static was given, the building process failed when trying to
2010 build pcretest and pcregrep. (For some reason it was using libtool to compile
2011 them, which is not right, as they aren't part of the library.)
2012
2013
2014 Version 3.8 18-Dec-01
2015 ---------------------
2016
2017 1. The experimental UTF-8 code was completely screwed up. It was packing the
2018 bytes in the wrong order. How dumb can you get?
2019
2020
2021 Version 3.7 29-Oct-01
2022 ---------------------
2023
2024 1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2025 This caused pcretest, when used on the test data, to segfault. Unfortunately,
2026 this didn't happen under Solaris 8, where I normally test things.
2027
2028 2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2029 doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2030 isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2031 this fix an hour or so after the initial 3.7 release.)
2032
2033
2034 Version 3.6 23-Oct-01
2035 ---------------------
2036
2037 1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2038 offsets passed as NULL with zero offset count.
2039
2040 2. The config.guess and config.sub files had not been updated when I moved to
2041 the latest autoconf.
2042
2043
2044 Version 3.5 15-Aug-01
2045 ---------------------
2046
2047 1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2048 had been forgotten.
2049
2050 2. By using declared but undefined structures, we can avoid using "void"
2051 definitions in pcre.h while keeping the internal definitions of the structures
2052 private.
2053
2054 3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2055 user point of view, this means that both static and shared libraries are built
2056 by default, but this can be individually controlled. More of the work of
2057 handling this static/shared cases is now inside libtool instead of PCRE's make
2058 file.
2059
2060 4. The pcretest utility is now installed along with pcregrep because it is
2061 useful for users (to test regexs) and by doing this, it automatically gets
2062 relinked by libtool. The documentation has been turned into a man page, so
2063 there are now .1, .txt, and .html versions in /doc.
2064
2065 5. Upgrades to pcregrep:
2066 (i) Added long-form option names like gnu grep.
2067 (ii) Added --help to list all options with an explanatory phrase.
2068 (iii) Added -r, --recursive to recurse into sub-directories.
2069 (iv) Added -f, --file to read patterns from a file.
2070
2071 6. pcre_exec() was referring to its "code" argument before testing that
2072 argument for NULL (and giving an error if it was NULL).
2073
2074 7. Upgraded Makefile.in to allow for compiling in a different directory from
2075 the source directory.
2076
2077 8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2078 options bits, the pointer it was passed was to an int instead of to an unsigned
2079 long int. This mattered only on 64-bit systems.
2080
2081 9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2082 generated) instead of pcre.in, which it its source. Also made the same change
2083 in several of the .c files.
2084
2085 10. A new release of gcc defines printf() as a macro, which broke pcretest
2086 because it had an ifdef in the middle of a string argument for printf(). Fixed
2087 by using separate calls to printf().
2088
2089 11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2090 script, to force use of CR or LF instead of \n in the source. On non-Unix
2091 systems, the value can be set in config.h.
2092
2093 12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2094 absolute limit. Changed the text of the error message to make this clear, and
2095 likewise updated the man page.
2096
2097 13. The limit of 99 on the number of capturing subpatterns has been removed.
2098 The new limit is 65535, which I hope will not be a "real" limit.
2099
2100
2101 Version 3.4 22-Aug-00
2102 ---------------------
2103
2104 1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2105
2106 2. Diagnose condition (?(0) as an error instead of crashing on matching.
2107
2108
2109 Version 3.3 01-Aug-00
2110 ---------------------
2111
2112 1. If an octal character was given, but the value was greater than \377, it
2113 was not getting masked to the least significant bits, as documented. This could
2114 lead to crashes in some systems.
2115
2116 2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2117 the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2118
2119 3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2120 These just pass their arguments on to (pcre_free)(), but they are provided
2121 because some uses of PCRE bind it to non-C systems that can call its functions,
2122 but cannot call free() or pcre_free() directly.
2123
2124 4. Add "make test" as a synonym for "make check". Corrected some comments in
2125 the Makefile.
2126
2127 5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2128 Makefile.
2129
2130 6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2131 command called pgrep for grepping around the active processes.
2132
2133 7. Added the beginnings of support for UTF-8 character strings.
2134
2135 8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2136 RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2137 the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2138 out for the ar command.)
2139
2140
2141 Version 3.2 12-May-00
2142 ---------------------
2143
2144 This is purely a bug fixing release.
2145
2146 1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2147 of ZA. This was just one example of several cases that could provoke this bug,
2148 which was introduced by change 9 of version 2.00. The code for breaking
2149 infinite loops after an iteration that matches an empty string was't working
2150 correctly.
2151
2152 2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2153 when matched against abbab (for example). After matching an empty string, it
2154 wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2155 caused it to match further down the string than it should.
2156
2157 3. The code contained an inclusion of sys/types.h. It isn't clear why this
2158 was there because it doesn't seem to be needed, and it causes trouble on some
2159 systems, as it is not a Standard C header. It has been removed.
2160
2161 4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2162 were reported on the Macintosh. The changes were from
2163
2164 while ((c = *(++ptr)) != 0 && c != '\n');
2165 to
2166 while ((c = *(++ptr)) != 0 && c != '\n') ;
2167
2168 Totally extraordinary, but if that's what it takes...
2169
2170 5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2171 available. Added HAVE_BCOPY and an autoconf test for it; if neither
2172 HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2173 assumes the way PCRE uses memmove() (always moving upwards).
2174
2175 6. PCRE is being used in one environment where strchr() is not available. There
2176 was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2177 faster code anyway.
2178
2179
2180 Version 3.1 09-Feb-00
2181 ---------------------
2182
2183 The only change in this release is the fixing of some bugs in Makefile.in for
2184 the "install" target:
2185
2186 (1) It was failing to install pcreposix.h.
2187
2188 (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2189
2190
2191 Version 3.0 01-Feb-00
2192 ---------------------
2193
2194 1. Add support for the /+ modifier to perltest (to output $` like it does in
2195 pcretest).
2196
2197 2. Add support for the /g modifier to perltest.
2198
2199 3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2200 matches null strings.
2201
2202 4. Fix perltest so that it doesn't do unwanted things when fed an empty
2203 pattern. Perl treats empty patterns specially - it reuses the most recent
2204 pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2205 effect.
2206
2207 5. The POSIX interface was broken in that it was just handing over the POSIX
2208 captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2209 required a bigger vector, with some working space on the end. This means that
2210 the POSIX wrapper now has to get and free some memory, and copy the results.
2211
2212 6. Added some simple autoconf support, placing the test data and the
2213 documentation in separate directories, re-organizing some of the
2214 information files, and making it build pcre-config (a GNU standard). Also added
2215 libtool support for building PCRE as a shared library, which is now the
2216 default.
2217
2218 7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2219 09 are not valid octal constants. Single digits will be used for minor values
2220 less than 10.
2221
2222 8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2223 existing programs that set these in the POSIX interface can use PCRE without
2224 modification.
2225
2226 9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2227 return all that pcre_info() returns, plus additional data. The pcre_info()
2228 function is retained for compatibility, but is considered to be obsolete.
2229
2230 10. Added experimental recursion feature (?R) to handle one common case that
2231 Perl 5.6 will be able to do with (?p{...}).
2232
2233 11. Added support for POSIX character classes like [:alpha:], which Perl is
2234 adopting.
2235
2236
2237 Version 2.08 31-Aug-99
2238 ----------------------
2239
2240 1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2241 trying to match at the startoffset position, but instead was moving forward to
2242 the next newline as if a previous match had failed.
2243
2244 2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2245 and could get into a loop if a null string was matched other than at the start
2246 of the subject.
2247
2248 3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2249 be distinguished at compile time, and for completeness also added PCRE_DATE.
2250
2251 5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2252 in GnuWin32 environments.
2253
2254
2255 Version 2.07 29-Jul-99
2256 ----------------------
2257
2258 1. The documentation is now supplied in plain text form and HTML as well as in
2259 the form of man page sources.
2260
2261 2. C++ compilers don't like assigning (void *) values to other pointer types.
2262 In particular this affects malloc(). Although there is no problem in Standard
2263 C, I've put in casts to keep C++ compilers happy.
2264
2265 3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2266 should be (const char *).
2267
2268 4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2269 be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2270 However, I haven't made this a standard facility. The documentation doesn't
2271 mention it, and the Makefile doesn't support it.
2272
2273 5. The Makefile now contains an "install" target, with editable destinations at
2274 the top of the file. The pcretest program is not installed.
2275
2276 6. pgrep -V now gives the PCRE version number and date.
2277
2278 7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2279 causing the entire string to be ignored, instead of just the last character.
2280
2281 8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2282 non-matching string, it can take a very, very long time, even for strings of
2283 quite modest length, because of the nested recursion. PCRE now does better in
2284 some of these cases. It does this by remembering the last required literal
2285 character in the pattern, and pre-searching the subject to ensure it is present
2286 before running the real match. In other words, it applies a heuristic to detect
2287 some types of certain failure quickly, and in the above example, if presented
2288 with a string that has no trailing " it gives "no match" very quickly.
2289
2290 9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2291 other alternatives are tried instead.
2292
2293
2294 Version 2.06 09-Jun-99
2295 ----------------------
2296
2297 1. Change pcretest's output for amount of store used to show just the code
2298 space, because the remainder (the data block) varies in size between 32-bit and
2299 64-bit systems.
2300
2301 2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2302 start matching at. This allows lookbehinds to work when searching for multiple
2303 occurrences in a string.
2304
2305 3. Added additional options to pcretest for testing multiple occurrences:
2306
2307 /+ outputs the rest of the string that follows a match
2308 /g loops for multiple occurrences, using the new startoffset argument
2309 /G loops for multiple occurrences by passing an incremented pointer
2310
2311 4. PCRE wasn't doing the "first character" optimization for patterns starting
2312 with \b or \B, though it was doing it for other lookbehind assertions. That is,
2313 it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2314 the letter 'x'. On long subject strings, this gives a significant speed-up.
2315
2316
2317 Version 2.05 21-Apr-99
2318 ----------------------
2319
2320 1. Changed the type of magic_number from int to long int so that it works
2321 properly on 16-bit systems.
2322
2323 2. Fixed a bug which caused patterns starting with .* not to work correctly
2324 when the subject string contained newline characters. PCRE was assuming
2325 anchoring for such patterns in all cases, which is not correct because .* will
2326 not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2327 DOTALL is set at top level; otherwise it knows that patterns starting with .*
2328 must be retried after every newline in the subject.
2329
2330
2331 Version 2.04 18-Feb-99
2332 ----------------------
2333
2334 1. For parenthesized subpatterns with repeats whose minimum was zero, the
2335 computation of the store needed to hold the pattern was incorrect (too large).
2336 If such patterns were nested a few deep, this could multiply and become a real
2337 problem.
2338
2339 2. Added /M option to pcretest to show the memory requirement of a specific
2340 pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2341
2342 3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2343 compiled in such a way that the backtracking after subsequent failure was
2344 pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2345 ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2346
2347
2348 Version 2.03 02-Feb-99
2349 ----------------------
2350
2351 1. Fixed typo and small mistake in man page.
2352
2353 2. Added 4th condition (GPL supersedes if conflict) and created separate
2354 LICENCE file containing the conditions.
2355
2356 3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2357 Perl, that is the internal \ allows the delimiter to be included in the
2358 pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2359 the final delimiter, add \ to the end of the pattern (to test the error).
2360
2361 4. Added the convenience functions for extracting substrings after a successful
2362 match. Updated pcretest to make it able to test these functions.
2363
2364
2365 Version 2.02 14-Jan-99
2366 ----------------------
2367
2368 1. Initialized the working variables associated with each extraction so that
2369 their saving and restoring doesn't refer to uninitialized store.
2370
2371 2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2372 compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2373 fix the problem.
2374
2375 3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2376 calls, and wasn't printing the correct value for compiling calls. Increased the
2377 default value of LOOPREPEAT, and the number of significant figures in the
2378 times.
2379
2380 4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2381
2382 5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2383 a building problem on Windows NT with a FAT file system.
2384
2385
2386 Version 2.01 21-Oct-98
2387 ----------------------
2388
2389 1. Changed the API for pcre_compile() to allow for the provision of a pointer
2390 to character tables built by pcre_maketables() in the current locale. If NULL
2391 is passed, the default tables are used.
2392
2393
2394 Version 2.00 24-Sep-98
2395 ----------------------
2396
2397 1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2398 it any more.
2399
2400 2. Allow quantification of (?>) groups, and make it work correctly.
2401
2402 3. The first character computation wasn't working for (?>) groups.
2403
2404 4. Correct the implementation of \Z (it is permitted to match on the \n at the
2405 end of the subject) and add 5.005's \z, which really does match only at the
2406 very end of the subject.
2407
2408 5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2409
2410 6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2411 DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2412 localized options. All options to pcre_study() were also removed.
2413
2414 7. Add other new features from 5.005:
2415
2416 $(?<= positive lookbehind
2417 $(?<! negative lookbehind
2418 (?imsx-imsx) added the unsetting capability
2419 such a setting is global if at outer level; local otherwise
2420 (?imsx-imsx:) non-capturing groups with option setting
2421 (?(cond)re|re) conditional pattern matching
2422
2423 A backreference to itself in a repeated group matches the previous
2424 captured string.
2425
2426 8. General tidying up of studying (both automatic and via "study")
2427 consequential on the addition of new assertions.
2428
2429 9. As in 5.005, unlimited repeated groups that could match an empty substring
2430 are no longer faulted at compile time. Instead, the loop is forcibly broken at
2431 runtime if any iteration does actually match an empty substring.
2432
2433 10. Include the RunTest script in the distribution.
2434
2435 11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2436 discrepancies, some of which were old and were also with respect to 5.004. They
2437 have now been fixed.
2438
2439
2440 Version 1.09 28-Apr-98
2441 ----------------------
2442
2443 1. A negated single character class followed by a quantifier with a minimum
2444 value of one (e.g. [^x]{1,6} ) was not compiled correctly. This could lead to
2445 program crashes, or just wrong answers. This did not apply to negated classes
2446 containing more than one character, or to minima other than one.
2447
2448
2449 Version 1.08 27-Mar-98
2450 ----------------------
2451
2452 1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
2453
2454 2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
2455 latter must appear before anything that relies on it in the pattern.
2456
2457
2458 Version 1.07 16-Feb-98
2459 ----------------------
2460
2461 1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
2462 repeat of a potentially empty string).
2463
2464
2465 Version 1.06 23-Jan-98
2466 ----------------------
2467
2468 1. Added Markus Oberhumer's little patches for C++.
2469
2470 2. Literal strings longer than 255 characters were broken.
2471
2472
2473 Version 1.05 23-Dec-97
2474 ----------------------
2475
2476 1. Negated character classes containing more than one character were failing if
2477 PCRE_CASELESS was set at run time.
2478
2479
2480 Version 1.04 19-Dec-97
2481 ----------------------
2482
2483 1. Corrected the man page, where some "const" qualifiers had been omitted.
2484
2485 2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
2486 input syntax.
2487
2488 3. Fixed memory leak which occurred when a regex with back references was
2489 matched with an offsets vector that wasn't big enough. The temporary memory
2490 that is used in this case wasn't being freed if the match failed.
2491
2492 4. Tidied pcretest to ensure it frees memory that it gets.
2493
2494 5. Temporary memory was being obtained in the case where the passed offsets
2495 vector was exactly big enough.
2496
2497 6. Corrected definition of offsetof() from change 5 below.
2498
2499 7. I had screwed up change 6 below and broken the rules for the use of
2500 setjmp(). Now fixed.
2501
2502
2503 Version 1.03 18-Dec-97
2504 ----------------------
2505
2506 1. A erroneous regex with a missing opening parenthesis was correctly
2507 diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
2508 on some systems.
2509
2510 2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
2511 it was reported that one broken compiler failed on the former because "code" is
2512 also an independent variable.
2513
2514 3. The erroneous regex a[]b caused an array overrun reference.
2515
2516 4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
2517 fail on data ending with that character. (It was going on too far, and checking
2518 the next character, typically a binary zero.) This was specific to the
2519 optimized code for single-character negative classes.
2520
2521 5. Added a contributed patch from the TIN world which does the following:
2522
2523 + Add an undef for memmove, in case the the system defines a macro for it.
2524
2525 + Add a definition of offsetof(), in case there isn't one. (I don't know
2526 the reason behind this - offsetof() is part of the ANSI standard - but
2527 it does no harm).
2528
2529 + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
2530 most of the places where whitespace preceded '#'. I have given up and
2531 allowed the remaining 2 cases to be at the margin.
2532
2533 + Rename some variables in pcre to eliminate shadowing. This seems very
2534 pedantic, but does no harm, of course.
2535
2536 6. Moved the call to setjmp() into its own function, to get rid of warnings
2537 from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.
2538
2539 7. Constructs such as \d{8,} were compiling into the equivalent of
2540 \d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
2541 outcome, but in this particular case used more store than had been allocated,
2542 which caused the bug to be discovered because it threw up an internal error.
2543
2544 8. The debugging code in both pcre and pcretest for outputting the compiled
2545 form of a regex was going wrong in the case of back references followed by
2546 curly-bracketed repeats.
2547
2548
2549 Version 1.02 12-Dec-97
2550 ----------------------
2551
2552 1. Typos in pcre.3 and comments in the source fixed.
2553
2554 2. Applied a contributed patch to get rid of places where it used to remove
2555 'const' from variables, and fixed some signed/unsigned and uninitialized
2556 variable warnings.
2557
2558 3. Added the "runtest" target to Makefile.
2559
2560 4. Set default compiler flag to -O2 rather than just -O.
2561
2562
2563 Version 1.01 19-Nov-97
2564 ----------------------
2565
2566 1. PCRE was failing to diagnose unlimited repeat of empty string for patterns
2567 like /([ab]*)*/, that is, for classes with more than one character in them.
2568
2569 2. Likewise, it wasn't diagnosing patterns with "once-only" subpatterns, such
2570 as /((?>a*))*/ (a PCRE_EXTRA facility).
2571
2572
2573 Version 1.00 18-Nov-97
2574 ----------------------
2575
2576 1. Added compile-time macros to support systems such as SunOS4 which don't have
2577 memmove() or strerror() but have other things that can be used instead.
2578
2579 2. Arranged that "make clean" removes the executables.
2580
2581
2582 Version 0.99 27-Oct-97
2583 ----------------------
2584
2585 1. Fixed bug in code for optimizing classes with only one character. It was
2586 initializing a 32-byte map regardless, which could cause it to run off the end
2587 of the memory it had got.
2588
2589 2. Added, conditional on PCRE_EXTRA, the proposed (?>REGEX) construction.
2590
2591
2592 Version 0.98 22-Oct-97
2593 ----------------------
2594
2595 1. Fixed bug in code for handling temporary memory usage when there are more
2596 back references than supplied space in the ovector. This could cause segfaults.
2597
2598
2599 Version 0.97 21-Oct-97
2600 ----------------------
2601
2602 1. Added the \X "cut" facility, conditional on PCRE_EXTRA.
2603
2604 2. Optimized negated single characters not to use a bit map.
2605
2606 3. Brought error texts together as macro definitions; clarified some of them;
2607 fixed one that was wrong - it said "range out of order" when it meant "invalid
2608 escape sequence".
2609
2610 4. Changed some char * arguments to const char *.
2611
2612 5. Added PCRE_NOTBOL and PCRE_NOTEOL (from POSIX).
2613
2614 6. Added the POSIX-style API wrapper in pcreposix.a and testing facilities in
2615 pcretest.
2616
2617
2618 Version 0.96 16-Oct-97
2619 ----------------------
2620
2621 1. Added a simple "pgrep" utility to the distribution.
2622
2623 2. Fixed an incompatibility with Perl: "{" is now treated as a normal character
2624 unless it appears in one of the precise forms "{ddd}", "{ddd,}", or "{ddd,ddd}"
2625 where "ddd" means "one or more decimal digits".
2626
2627 3. Fixed serious bug. If a pattern had a back reference, but the call to
2628 pcre_exec() didn't supply a large enough ovector to record the related
2629 identifying subpattern, the match always failed. PCRE now remembers the number
2630 of the largest back reference, and gets some temporary memory in which to save
2631 the offsets during matching if necessary, in order to ensure that
2632 backreferences always work.
2633
2634 4. Increased the compatibility with Perl in a number of ways:
2635
2636 (a) . no longer matches \n by default; an option PCRE_DOTALL is provided
2637 to request this handling. The option can be set at compile or exec time.
2638
2639 (b) $ matches before a terminating newline by default; an option
2640 PCRE_DOLLAR_ENDONLY is provided to override this (but not in multiline
2641 mode). The option can be set at compile or exec time.
2642
2643 (c) The handling of \ followed by a digit other than 0 is now supposed to be
2644 the same as Perl's. If the decimal number it represents is less than 10
2645 or there aren't that many previous left capturing parentheses, an octal
2646 escape is read. Inside a character class, it's always an octal escape,
2647 even if it is a single digit.
2648
2649 (d) An escaped but undefined alphabetic character is taken as a literal,
2650 unless PCRE_EXTRA is set. Currently this just reserves the remaining
2651 escapes.
2652
2653 (e) {0} is now permitted. (The previous item is removed from the compiled
2654 pattern).
2655
2656 5. Changed all the names of code files so that the basic parts are no longer
2657 than 10 characters, and abolished the teeny "globals.c" file.
2658
2659 6. Changed the handling of character classes; they are now done with a 32-byte
2660 bit map always.
2661
2662 7. Added the -d and /D options to pcretest to make it possible to look at the
2663 internals of compilation without having to recompile pcre.
2664
2665
2666 Version 0.95 23-Sep-97
2667 ----------------------
2668
2669 1. Fixed bug in pre-pass concerning escaped "normal" characters such as \x5c or
2670 \x20 at the start of a run of normal characters. These were being treated as
2671 real characters, instead of the source characters being re-checked.
2672
2673
2674 Version 0.94 18-Sep-97
2675 ----------------------
2676
2677 1. The functions are now thread-safe, with the caveat that the global variables
2678 containing pointers to malloc() and free() or alternative functions are the
2679 same for all threads.
2680
2681 2. Get pcre_study() to generate a bitmap of initial characters for non-
2682 anchored patterns when this is possible, and use it if passed to pcre_exec().
2683
2684
2685 Version 0.93 15-Sep-97
2686 ----------------------
2687
2688 1. /(b)|(:+)/ was computing an incorrect first character.
2689
2690 2. Add pcre_study() to the API and the passing of pcre_extra to pcre_exec(),
2691 but not actually doing anything yet.
2692
2693 3. Treat "-" characters in classes that cannot be part of ranges as literals,
2694 as Perl does (e.g. [-az] or [az-]).
2695
2696 4. Set the anchored flag if a branch starts with .* or .*? because that tests
2697 all possible positions.
2698
2699 5. Split up into different modules to avoid including unneeded functions in a
2700 compiled binary. However, compile and exec are still in one module. The "study"
2701 function is split off.
2702
2703 6. The character tables are now in a separate module whose source is generated
2704 by an auxiliary program - but can then be edited by hand if required. There are
2705 now no calls to isalnum(), isspace(), isdigit(), isxdigit(), tolower() or
2706 toupper() in the code.
2707
2708 7. Turn the malloc/free funtions variables into pcre_malloc and pcre_free and
2709 make them global. Abolish the function for setting them, as the caller can now
2710 set them directly.
2711
2712
2713 Version 0.92 11-Sep-97
2714 ----------------------
2715
2716 1. A repeat with a fixed maximum and a minimum of 1 for an ordinary character
2717 (e.g. /a{1,3}/) was broken (I mis-optimized it).
2718
2719 2. Caseless matching was not working in character classes if the characters in
2720 the pattern were in upper case.
2721
2722 3. Make ranges like [W-c] work in the same way as Perl for caseless matching.
2723
2724 4. Make PCRE_ANCHORED public and accept as a compile option.
2725
2726 5. Add an options word to pcre_exec() and accept PCRE_ANCHORED and
2727 PCRE_CASELESS at run time. Add escapes \A and \I to pcretest to cause it to
2728 pass them.
2729
2730 6. Give an error if bad option bits passed at compile or run time.
2731
2732 7. Add PCRE_MULTILINE at compile and exec time, and (?m) as well. Add \M to
2733 pcretest to cause it to pass that flag.
2734
2735 8. Add pcre_info(), to get the number of identifying subpatterns, the stored
2736 options, and the first character, if set.
2737
2738 9. Recognize C+ or C{n,m} where n >= 1 as providing a fixed starting character.
2739
2740
2741 Version 0.91 10-Sep-97
2742 ----------------------
2743
2744 1. PCRE was failing to diagnose unlimited repeats of subpatterns that could
2745 match the empty string as in /(a*)*/. It was looping and ultimately crashing.
2746
2747 2. PCRE was looping on encountering an indefinitely repeated back reference to
2748 a subpattern that had matched an empty string, e.g. /(a|)\1*/. It now does what
2749 Perl does - treats the match as successful.
2750
2751 ****

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