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Revision 190 - (hide annotations) (download)
Thu Jul 19 10:38:20 2007 UTC (7 years, 9 months ago) by ph10
File size: 131154 byte(s)
Fix bug with .*$ when run in not-DOTALL UTF-8 mode; small performance 
improvement for .* in DOTALL UTF-8 mode.

1 nigel 3 ChangeLog for PCRE
2     ------------------
4 ph10 189 Version 7.3 05-Jul-07
5 ph10 157 ---------------------
7 ph10 189 1. In the rejigging of the build system that eventually resulted in 7.1, the
8     line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
9     brackets there is not right, since it causes compilers to look for an
10     installed pcre.h, not the version that is in the source that is being
11     compiled (which of course may be different). I have changed it back to:
13     #include "pcre.h"
15     I have a vague recollection that the change was concerned with compiling in
16     different directories, but in the new build system, that is taken care of
17     by the VPATH setting the Makefile.
18 ph10 190
19     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
20     when the subject happened to end in the byte 0x85 (e.g. if the last
21     character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
22     characters but of course it shouldn't be taken as a newline when it is part
23     of another character. The bug was that, for an unlimited repeat of . in
24     not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
25     characters when looking for a newline.
27     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
28 ph10 189
31     Version 7.2 19-Jun-07
32     ---------------------
34 ph10 157 1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
35     which is apparently normally available under Windows.
36 ph10 159
37     2. Re-jig the pcregrep tests with different newline settings in an attempt
38     to make them independent of the local environment's newline setting.
39 ph10 157
40 ph10 160 3. Add code to configure.ac to remove -g from the CFLAGS default settings.
41 ph10 165
42 ph10 161 4. Some of the "internals" tests were previously cut out when the link size
43     was not 2, because the output contained actual offsets. The recent new
44 ph10 165 "Z" feature of pcretest means that these can be cut out, making the tests
45     usable with all link sizes.
47 ph10 164 5. Implemented Stan Switzer's goto replacement for longjmp() when not using
48     stack recursion. This gives a massive performance boost under BSD, but just
49 ph10 165 a small improvement under Linux. However, it saves one field in the frame
50 ph10 164 in all cases.
51 ph10 172
52 ph10 166 6. Added more features from the forthcoming Perl 5.10:
53 ph10 172
54 ph10 166 (a) (?-n) (where n is a string of digits) is a relative subroutine or
55     recursion call. It refers to the nth most recently opened parentheses.
56 ph10 172
57 ph10 166 (b) (?+n) is also a relative subroutine call; it refers to the nth next
58 ph10 172 to be opened parentheses.
60     (c) Conditions that refer to capturing parentheses can be specified
61 ph10 167 relatively, for example, (?(-2)... or (?(+3)...
62 ph10 172
63 ph10 168 (d) \K resets the start of the current match so that everything before
64 ph10 172 is not part of it.
66 ph10 171 (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
67 ph10 172
68 ph10 171 (f) \g{name} is another synonym - part of Perl 5.10's unification of
69 ph10 172 reference syntax.
70 ph10 182
71 ph10 175 (g) (?| introduces a group in which the numbering of parentheses in each
72 ph10 182 alternative starts with the same number.
73 ph10 172
74 ph10 182 (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
76 ph10 172 7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
79     8. A pattern such as (.*(.)?)* caused pcre_exec() to fail by either not
80     terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
81 ph10 170 for detecting groups that can match an empty string.
82 ph10 159
83 ph10 172 9. A pattern with a very large number of alternatives (more than several
84     hundred) was running out of internal workspace during the pre-compile
85     phase, where pcre_compile() figures out how much memory will be needed. A
86     bit of new cunning has reduced the workspace needed for groups with
87     alternatives. The 1000-alternative test pattern now uses 12 bytes of
88     workspace instead of running out of the 4096 that are available.
89 ph10 182
90 ph10 176 10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
91 ph10 172
92 ph10 179 11. Applied patch from Google to remove an optimization that didn't quite work.
93     The report of the bug said:
94 ph10 182
95 ph10 179 pcrecpp::RE("a*").FullMatch("aaa") matches, while
96     pcrecpp::RE("a*?").FullMatch("aaa") does not, and
97 ph10 182 pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
98 ph10 185
99 ph10 184 12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
100 ph10 185 it matched the wrong number of bytes.
101 ph10 172
102 ph10 179
103 ph10 155 Version 7.1 24-Apr-07
104 ph10 98 ---------------------
106 ph10 111 1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
107 ph10 122 that is more "standard", making use of automake and other Autotools. There
108 ph10 99 is some re-arrangement of the files and adjustment of comments consequent
109     on this.
110 ph10 111
111     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
112     for recursive directory scanning broke on some systems because the files
113     are not scanned in any specific order and on different systems the order
114     was different. A call to "sort" has been inserted into RunGrepTest for the
115     approprate test as a short-term fix. In the longer term there may be an
116 ph10 100 alternative.
117 ph10 111
118 ph10 100 3. I had an email from Eric Raymond about problems translating some of PCRE's
119 ph10 111 man pages to HTML (despite the fact that I distribute HTML pages, some
120     people do their own conversions for various reasons). The problems
121     concerned the use of low-level troff macros .br and .in. I have therefore
122     removed all such uses from the man pages (some were redundant, some could
123 ph10 113 be replaced by .nf/.fi pairs). The 132html script that I use to generate
124     HTML has been updated to handle .nf/.fi and to complain if it encounters
125     .br or .in.
126 ph10 111
127 ph10 100 4. Updated comments in configure.ac that get placed in config.h.in and also
128 ph10 123 arranged for config.h to be included in the distribution, with the name
129 ph10 111 config.h.generic, for the benefit of those who have to compile without
130     Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
132     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
133     Weber: (1) pcre_internal.h was missing some function renames; (2) updated
134 ph10 127 makevp.bat for the current PCRE, using the additional files
135 ph10 135 makevp_c.txt, makevp_l.txt, and pcregexp.pas.
136 ph10 111
137     6. A Windows user reported a minor discrepancy with test 2, which turned out
138     to be caused by a trailing space on an input line that had got lost in his
139 ph10 102 copy. The trailing space was an accident, so I've just removed it.
140 ph10 111
141 ph10 104 7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
142 ph10 111 that is needed.
144 ph10 105 8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
145     as "const" (a) because they are and (b) because it helps the PHP
146     maintainers who have recently made a script to detect big data structures
147 ph10 111 in the php code that should be moved to the .rodata section. I remembered
148     to update Builducptable as well, so it won't revert if ucptable.h is ever
149 ph10 105 re-created.
150 ph10 111
151     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
152 ph10 107 pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
153 ph10 111 order to be able to cut out the UTF-8 tables in the latter when UTF-8
154     support is not required. This saves 1.5-2K of code, which is important in
155 ph10 107 some applications.
156 ph10 111
157 ph10 110 Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
158 ph10 111 so as not to refer to the tables, even though these functions will never be
159     called when UTF-8 support is disabled. Otherwise there are problems with a
160     shared library.
162 ph10 118 10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
164     (a) It was defining its arguments as char * instead of void *.
166 ph10 123 (b) It was assuming that all moves were upwards in memory; this was true
167     a long time ago when I wrote it, but is no longer the case.
169 ph10 118 The emulated memove() is provided for those environments that have neither
170 ph10 123 memmove() nor bcopy(). I didn't think anyone used it these days, but that
171 ph10 118 is clearly not the case, as these two bugs were recently reported.
172 ph10 123
173 ph10 111 11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
174 ph10 123 and Detrail to create the HTML documentation, the .txt form of the man
175     pages, and it removes trailing spaces from listed files. It also creates
176     pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
177     case, it wraps all the #defines with #ifndefs. This script should be run
178 ph10 111 before "make dist".
179 ph10 123
180 ph10 115 12. Fixed two fairly obscure bugs concerned with quantified caseless matching
181     with Unicode property support.
182 ph10 123
183     (a) For a maximizing quantifier, if the two different cases of the
184     character were of different lengths in their UTF-8 codings (there are
185     some cases like this - I found 11), and the matching function had to
186 ph10 115 back up over a mixture of the two cases, it incorrectly assumed they
187     were both the same length.
188 ph10 123
189     (b) When PCRE was configured to use the heap rather than the stack for
190     recursion during matching, it was not correctly preserving the data for
191     the other case of a UTF-8 character when checking ahead for a match
192     while processing a minimizing repeat. If the check also involved
193 ph10 115 matching a wide character, but failed, corruption could cause an
194     erroneous result when trying to check for a repeat of the original
195     character.
196 ph10 123
197 ph10 116 13. Some tidying changes to the testing mechanism:
198 ph10 98
199 ph10 116 (a) The RunTest script now detects the internal link size and whether there
200     is UTF-8 and UCP support by running ./pcretest -C instead of relying on
201 ph10 123 values substituted by "configure". (The RunGrepTest script already did
202     this for UTF-8.) The configure.ac script no longer substitutes the
203     relevant variables.
205 ph10 116 (b) The debugging options /B and /D in pcretest show the compiled bytecode
206     with length and offset values. This means that the output is different
207     for different internal link sizes. Test 2 is skipped for link sizes
208     other than 2 because of this, bypassing the problem. Unfortunately,
209     there was also a test in test 3 (the locale tests) that used /B and
210 ph10 123 failed for link sizes other than 2. Rather than cut the whole test out,
211     I have added a new /Z option to pcretest that replaces the length and
212     offset values with spaces. This is now used to make test 3 independent
213 ph10 122 of link size. (Test 2 will be tidied up later.)
214 ph10 123
215     14. If erroroffset was passed as NULL to pcre_compile, it provoked a
216 ph10 122 segmentation fault instead of returning the appropriate error message.
217 ph10 134
218 ph10 131 15. In multiline mode when the newline sequence was set to "any", the pattern
219 ph10 134 ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
220     This doesn't seem right; it now treats the CRLF combination as the line
221     ending, and so does not match in that case. It's only a pattern such as ^$
222     that would hit this one: something like ^ABC$ would have failed after \r
223     and then tried again after \r\n.
225 ph10 131 16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
226 ph10 134 in an attempt to make files that differ only in their line terminators
227     compare equal. This works on Linux.
228 ph10 142
229 ph10 141 17. Under certain error circumstances pcregrep might try to free random memory
230     as it exited. This is now fixed, thanks to valgrind.
231 ph10 142
232 ph10 141 19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
233 ph10 142 "abc\r\n\r\n", it found an unwanted second match after the second \r. This
234     was because its rules for how to advance for /g after matching an empty
235 ph10 143 string at the end of a line did not allow for this case. They now check for
236     it specially.
237 ph10 150
238     20. pcretest is supposed to handle patterns and data of any length, by
239     extending its buffers when necessary. It was getting this wrong when the
240 ph10 147 buffer for a data line had to be extended.
241 ph10 150
242 ph10 149 21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
243 ph10 150 CRLF as a newline sequence.
244 ph10 152
245 ph10 151 22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
246 ph10 152 out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
247     I have nevertheless tidied it up.
248 ph10 111
249 ph10 152 23. Added some casts to kill warnings from HP-UX ia64 compiler.
250 ph10 123
251 ph10 153 24. Added a man page for pcre-config.
252 ph10 152
253 ph10 153
254 nigel 93 Version 7.0 19-Dec-06
255     ---------------------
257     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
258     moving to gcc 4.1.1.
260     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
261     sys/time.h, which is documented as needed for this function. It doesn't
262     seem to matter on Linux, but it showed up on some releases of OS X.
264     3. It seems that there are systems where bytes whose values are greater than
265     127 match isprint() in the "C" locale. The "C" locale should be the
266     default when a C program starts up. In most systems, only ASCII printing
267     characters match isprint(). This difference caused the output from pcretest
268     to vary, making some of the tests fail. I have changed pcretest so that:
270     (a) When it is outputting text in the compiled version of a pattern, bytes
271     other than 32-126 are always shown as hex escapes.
273     (b) When it is outputting text that is a matched part of a subject string,
274     it does the same, unless a different locale has been set for the match
275     (using the /L modifier). In this case, it uses isprint() to decide.
277     4. Fixed a major bug that caused incorrect computation of the amount of memory
278     required for a compiled pattern when options that changed within the
279     pattern affected the logic of the preliminary scan that determines the
280     length. The relevant options are -x, and -i in UTF-8 mode. The result was
281     that the computed length was too small. The symptoms of this bug were
282     either the PCRE error "internal error: code overflow" from pcre_compile(),
283     or a glibc crash with a message such as "pcretest: free(): invalid next
284     size (fast)". Examples of patterns that provoked this bug (shown in
285     pcretest format) are:
287     /(?-x: )/x
288     /(?x)(?-x: \s*#\s*)/
289     /((?i)[\x{c0}])/8
290     /(?i:[\x{c0}])/8
292     HOWEVER: Change 17 below makes this fix obsolete as the memory computation
293     is now done differently.
295     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
296     wrapper classes; (b) implement a new function in the C++ scanner that is
297     more efficient than the old way of doing things because it avoids levels of
298     recursion in the regex matching; (c) add a paragraph to the documentation
299     for the FullMatch() function.
301     6. The escape sequence \n was being treated as whatever was defined as
302     "newline". Not only was this contrary to the documentation, which states
303     that \n is character 10 (hex 0A), but it also went horribly wrong when
304     "newline" was defined as CRLF. This has been fixed.
306     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
307     was being set to -1 for the "end of line" case (supposedly a value that no
308     character can have). Though this value is never used (the check for end of
309     line is "zero bytes in current character"), it caused compiler complaints.
310     I've changed it to 0xffffffff.
312     8. In pcre_version.c, the version string was being built by a sequence of
313     C macros that, in the event of PCRE_PRERELEASE being defined as an empty
314     string (as it is for production releases) called a macro with an empty
315     argument. The C standard says the result of this is undefined. The gcc
316     compiler treats it as an empty string (which was what was wanted) but it is
317     reported that Visual C gives an error. The source has been hacked around to
318     avoid this problem.
320     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
321     builds of pcretest, and changed the call to _setmode() to use _O_BINARY
322     instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
323     of them did).
325     10. Originally, pcretest opened its input and output without "b"; then I was
326     told that "b" was needed in some environments, so it was added for release
327     5.0 to both the input and output. (It makes no difference on Unix-like
328     systems.) Later I was told that it is wrong for the input on Windows. I've
329     now abstracted the modes into two macros, to make it easier to fiddle with
330     them, and removed "b" from the input mode under Windows.
332     11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
334     12. Added -help and --help to pcretest as an official way of being reminded
335     of the options.
337     13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
338     and pcrecpp.cc because they annoy compilers at high warning levels.
340     14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
342     15. Fixed an occurrence of == in configure.ac that should have been = (shell
343     scripts are not C programs :-) and which was not noticed because it works
344     on Linux.
346     16. pcretest is supposed to handle any length of pattern and data line (as one
347     line or as a continued sequence of lines) by extending its input buffer if
348     necessary. This feature was broken for very long pattern lines, leading to
349     a string of junk being passed to pcre_compile() if the pattern was longer
350     than about 50K.
352     17. I have done a major re-factoring of the way pcre_compile() computes the
353     amount of memory needed for a compiled pattern. Previously, there was code
354     that made a preliminary scan of the pattern in order to do this. That was
355     OK when PCRE was new, but as the facilities have expanded, it has become
356     harder and harder to keep it in step with the real compile phase, and there
357     have been a number of bugs (see for example, 4 above). I have now found a
358     cunning way of running the real compile function in a "fake" mode that
359     enables it to compute how much memory it would need, while actually only
360     ever using a few hundred bytes of working memory and without too many
361     tests of the mode. This should make future maintenance and development
362     easier. A side effect of this work is that the limit of 200 on the nesting
363     depth of parentheses has been removed (though this was never a serious
364     limitation, I suspect). However, there is a downside: pcre_compile() now
365     runs more slowly than before (30% or more, depending on the pattern). I
366     hope this isn't a big issue. There is no effect on runtime performance.
368     18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
369     newline (only possible for the last line of a file) and it was a
370     pattern that set a locale (followed by /Lsomething), pcretest crashed.
372     19. Added additional timing features to pcretest. (1) The -tm option now times
373     matching only, not compiling. (2) Both -t and -tm can be followed, as a
374     separate command line item, by a number that specifies the number of
375     repeats to use when timing. The default is 50000; this gives better
376     precision, but takes uncomfortably long for very large patterns.
378     20. Extended pcre_study() to be more clever in cases where a branch of a
379     subpattern has no definite first character. For example, (a*|b*)[cd] would
380     previously give no result from pcre_study(). Now it recognizes that the
381     first character must be a, b, c, or d.
383     21. There was an incorrect error "recursive call could loop indefinitely" if
384     a subpattern (or the entire pattern) that was being tested for matching an
385     empty string contained only one non-empty item after a nested subpattern.
386     For example, the pattern (?>\x{100}*)\d(?R) provoked this error
387     incorrectly, because the \d was being skipped in the check.
389     22. The pcretest program now has a new pattern option /B and a command line
390     option -b, which is equivalent to adding /B to every pattern. This causes
391     it to show the compiled bytecode, without the additional information that
392     -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
393     is the same as /B/I).
395     23. A new optimization is now able automatically to treat some sequences such
396     as a*b as a*+b. More specifically, if something simple (such as a character
397     or a simple class like \d) has an unlimited quantifier, and is followed by
398     something that cannot possibly match the quantified thing, the quantifier
399     is automatically "possessified".
401     24. A recursive reference to a subpattern whose number was greater than 39
402     went wrong under certain circumstances in UTF-8 mode. This bug could also
403     have affected the operation of pcre_study().
405     25. Realized that a little bit of performance could be had by replacing
406     (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
408     26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
410     27. Possessive quantifiers such as a++ were previously implemented by turning
411     them into atomic groups such as ($>a+). Now they have their own opcodes,
412     which improves performance. This includes the automatically created ones
413     from 23 above.
415     28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
416     lookahead was broken if it was not anchored. PCRE was mistakenly expecting
417     the first matched character to be a colon. This applied both to named and
418     numbered groups.
420     29. The ucpinternal.h header file was missing its idempotency #ifdef.
422     30. I was sent a "project" file called libpcre.a.dev which I understand makes
423     building PCRE on Windows easier, so I have included it in the distribution.
425     31. There is now a check in pcretest against a ridiculously large number being
426     returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
427     loop, the loop is abandoned.
429     32. Forward references to subpatterns in conditions such as (?(2)...) where
430     subpattern 2 is defined later cause pcre_compile() to search forwards in
431     the pattern for the relevant set of parentheses. This search went wrong
432     when there were unescaped parentheses in a character class, parentheses
433     escaped with \Q...\E, or parentheses in a #-comment in /x mode.
435     33. "Subroutine" calls and backreferences were previously restricted to
436     referencing subpatterns earlier in the regex. This restriction has now
437     been removed.
439     34. Added a number of extra features that are going to be in Perl 5.10. On the
440     whole, these are just syntactic alternatives for features that PCRE had
441     previously implemented using the Python syntax or my own invention. The
442     other formats are all retained for compatibility.
444     (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
445     as (?P<name>...). The new forms, as well as being in Perl 5.10, are
446     also .NET compatible.
448     (b) A recursion or subroutine call to a named group can now be defined as
449     (?&name) as well as (?P>name).
451     (c) A backreference to a named group can now be defined as \k<name> or
452     \k'name' as well as (?P=name). The new forms, as well as being in Perl
453     5.10, are also .NET compatible.
455     (d) A conditional reference to a named group can now use the syntax
456     (?(<name>) or (?('name') as well as (?(name).
458     (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
459     groups (named and numbered) that are never evaluated inline, but can be
460     called as "subroutines" from elsewhere. In effect, the DEFINE condition
461     is always false. There may be only one alternative in such a group.
463     (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
464     as the simple (?(R). The condition is true only if the most recent
465     recursion is that of the given number or name. It does not search out
466     through the entire recursion stack.
468     (g) The escape \gN or \g{N} has been added, where N is a positive or
469     negative number, specifying an absolute or relative reference.
471     35. Tidied to get rid of some further signed/unsigned compiler warnings and
472     some "unreachable code" warnings.
474     36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
475     things, this adds five new scripts.
477     37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
478     There were also incompatibilities regarding the handling of \Q..\E inside
479     character classes, for example with patterns like [\Qa\E-\Qz\E] where the
480     hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
482     38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
483     matches an empty string, and forcibly breaks the loop. There were bugs in
484     this code in non-simple cases. For a pattern such as ^(a()*)* matched
485     against aaaa the result was just "a" rather than "aaaa", for example. Two
486     separate and independent bugs (that affected different cases) have been
487     fixed.
489     39. Refactored the code to abolish the use of different opcodes for small
490     capturing bracket numbers. This is a tidy that I avoided doing when I
491     removed the limit on the number of capturing brackets for 3.5 back in 2001.
492     The new approach is not only tidier, it makes it possible to reduce the
493     memory needed to fix the previous bug (38).
495     40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
496     sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
497     processing dot, circumflex, or dollar metacharacters, or #-comments in /x
498     mode.
500     41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
501     report.
503     42. Applied patch, originally from Ari Pollak, modified by Google, to allow
504     copy construction and assignment in the C++ wrapper.
506     43. Updated pcregrep to support "--newline=any". In the process, I fixed a
507     couple of bugs that could have given wrong results in the "--newline=crlf"
508     case.
510     44. Added a number of casts and did some reorganization of signed/unsigned int
511     variables following suggestions from Dair Grant. Also renamed the variable
512     "this" as "item" because it is a C++ keyword.
514     45. Arranged for dftables to add
516     #include "pcre_internal.h"
518     to pcre_chartables.c because without it, gcc 4.x may remove the array
519     definition from the final binary if PCRE is built into a static library and
520     dead code stripping is activated.
522     46. For an unanchored pattern, if a match attempt fails at the start of a
523     newline sequence, and the newline setting is CRLF or ANY, and the next two
524     characters are CRLF, advance by two characters instead of one.
527 nigel 91 Version 6.7 04-Jul-06
528     ---------------------
530     1. In order to handle tests when input lines are enormously long, pcretest has
531     been re-factored so that it automatically extends its buffers when
532     necessary. The code is crude, but this _is_ just a test program. The
533     default size has been increased from 32K to 50K.
535     2. The code in pcre_study() was using the value of the re argument before
536     testing it for NULL. (Of course, in any sensible call of the function, it
537     won't be NULL.)
539     3. The memmove() emulation function in pcre_internal.h, which is used on
540     systems that lack both memmove() and bcopy() - that is, hardly ever -
541     was missing a "static" storage class specifier.
543     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
544     containing an extended class (one that cannot be represented by a bitmap
545     because it contains high-valued characters or Unicode property items, e.g.
546     [\pZ]). Almost always one would set UTF-8 mode when processing such a
547     pattern, but PCRE should not loop if you do not (it no longer does).
548     [Detail: two cases were found: (a) a repeated subpattern containing an
549     extended class; (b) a recursive reference to a subpattern that followed a
550     previous extended class. It wasn't skipping over the extended class
551     correctly when UTF-8 mode was not set.]
553     5. A negated single-character class was not being recognized as fixed-length
554     in lookbehind assertions such as (?<=[^f]), leading to an incorrect
555     compile error "lookbehind assertion is not fixed length".
557     6. The RunPerlTest auxiliary script was showing an unexpected difference
558     between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
559     write a Perl script that can interpret lines of an input file either as
560     byte characters or as UTF-8, which is what "perltest" was being required to
561     do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
562     can't do is switch easily at run time between having the "use utf8;" pragma
563     or not. In the end, I fudged it by using the RunPerlTest script to insert
564     "use utf8;" explicitly for the UTF-8 tests.
566     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
567     the end of the subject string, contrary to the documentation and to what
568     Perl does. This was true of both matching functions. Now it matches only at
569     the start of the subject and immediately after *internal* newlines.
571     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
572     a pointer to an int instead of a pointer to an unsigned long int. This
573     caused problems on 64-bit systems.
575     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
576     instance of the 'standard' template library not being so standard".
578     10. There was no check on the number of named subpatterns nor the maximum
579     length of a subpattern name. The product of these values is used to compute
580     the size of the memory block for a compiled pattern. By supplying a very
581     long subpattern name and a large number of named subpatterns, the size
582     computation could be caused to overflow. This is now prevented by limiting
583     the length of names to 32 characters, and the number of named subpatterns
584     to 10,000.
586     11. Subpatterns that are repeated with specific counts have to be replicated in
587     the compiled pattern. The size of memory for this was computed from the
588     length of the subpattern and the repeat count. The latter is limited to
589     65535, but there was no limit on the former, meaning that integer overflow
590     could in principle occur. The compiled length of a repeated subpattern is
591     now limited to 30,000 bytes in order to prevent this.
593     12. Added the optional facility to have named substrings with the same name.
595     13. Added the ability to use a named substring as a condition, using the
596     Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
597     are numbers (not recommended). Forward references are permitted.
599     14. Added forward references in named backreferences (if you see what I mean).
601     15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
602     pattern could run off the end of the subject. For example, the pattern
603     "(?s)(.{1,5})"8 did this with the subject "ab".
605     16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
606     PCRE_CASELESS was set when matching characters that were quantified with ?
607     or *.
609     17. A character class other than a single negated character that had a minimum
610     but no maximum quantifier - for example [ab]{6,} - was not handled
611     correctly by pce_dfa_exec(). It would match only one character.
613     18. A valid (though odd) pattern that looked like a POSIX character
614     class but used an invalid character after [ (for example [[,abc,]]) caused
615     pcre_compile() to give the error "Failed: internal error: code overflow" or
616     in some cases to crash with a glibc free() error. This could even happen if
617     the pattern terminated after [[ but there just happened to be a sequence of
618     letters, a binary zero, and a closing ] in the memory that followed.
620     19. Perl's treatment of octal escapes in the range \400 to \777 has changed
621     over the years. Originally (before any Unicode support), just the bottom 8
622     bits were taken. Thus, for example, \500 really meant \100. Nowadays the
623     output from "man perlunicode" includes this:
625     The regular expression compiler produces polymorphic opcodes. That
626     is, the pattern adapts to the data and automatically switches to
627     the Unicode character scheme when presented with Unicode data--or
628     instead uses a traditional byte scheme when presented with byte
629     data.
631     Sadly, a wide octal escape does not cause a switch, and in a string with
632     no other multibyte characters, these octal escapes are treated as before.
633     Thus, in Perl, the pattern /\500/ actually matches \100 but the pattern
634     /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
635     Unicode string.
637     I have not perpetrated such confusion in PCRE. Up till now, it took just
638     the bottom 8 bits, as in old Perl. I have now made octal escapes with
639     values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
640     translate to the appropriate multibyte character.
642     29. Applied some refactoring to reduce the number of warnings from Microsoft
643     and Borland compilers. This has included removing the fudge introduced
644     seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
645     a warning about an unused variable.
647     21. PCRE has not included VT (character 0x0b) in the set of whitespace
648     characters since release 4.0, because Perl (from release 5.004) does not.
649     [Or at least, is documented not to: some releases seem to be in conflict
650     with the documentation.] However, when a pattern was studied with
651     pcre_study() and all its branches started with \s, PCRE still included VT
652     as a possible starting character. Of course, this did no harm; it just
653     caused an unnecessary match attempt.
655     22. Removed a now-redundant internal flag bit that recorded the fact that case
656     dependency changed within the pattern. This was once needed for "required
657     byte" processing, but is no longer used. This recovers a now-scarce options
658     bit. Also moved the least significant internal flag bit to the most-
659     significant bit of the word, which was not previously used (hangover from
660     the days when it was an int rather than a uint) to free up another bit for
661     the future.
663     23. Added support for CRLF line endings as well as CR and LF. As well as the
664     default being selectable at build time, it can now be changed at runtime
665     via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
666     specify that it is scanning data with non-default line endings.
668     24. Changed the definition of CXXLINK to make it agree with the definition of
669     LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
671     25. Applied Ian Taylor's patches to avoid using another stack frame for tail
672     recursions. This makes a big different to stack usage for some patterns.
674     26. If a subpattern containing a named recursion or subroutine reference such
675     as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
676     the space required for the compiled pattern went wrong and gave too small a
677     value. Depending on the environment, this could lead to "Failed: internal
678     error: code overflow at offset 49" or "glibc detected double free or
679     corruption" errors.
681     27. Applied patches from Google (a) to support the new newline modes and (b) to
682     advance over multibyte UTF-8 characters in GlobalReplace.
684     28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
685     difference for some implementation of PCRE in some Windows version.
687     29. Added some extra testing facilities to pcretest:
689     \q<number> in a data line sets the "match limit" value
690     \Q<number> in a data line sets the "match recursion limt" value
691     -S <number> sets the stack size, where <number> is in megabytes
693     The -S option isn't available for Windows.
696 nigel 89 Version 6.6 06-Feb-06
697     ---------------------
699     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
700     in pcreposix.h. I have copied the definition from pcre.h.
702     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
703     because pcre.h is no longer a built file.
705     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
706     not normally included in the compiled code.
709 nigel 87 Version 6.5 01-Feb-06
710     ---------------------
712     1. When using the partial match feature with pcre_dfa_exec(), it was not
713     anchoring the second and subsequent partial matches at the new starting
714     point. This could lead to incorrect results. For example, with the pattern
715     /1234/, partially matching against "123" and then "a4" gave a match.
717     2. Changes to pcregrep:
719     (a) All non-match returns from pcre_exec() were being treated as failures
720     to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
721     error message is output. Some extra information is given for the
723     probably the only errors that are likely to be caused by users (by
724     specifying a regex that has nested indefinite repeats, for instance).
725     If there are more than 20 of these errors, pcregrep is abandoned.
727     (b) A binary zero was treated as data while matching, but terminated the
728     output line if it was written out. This has been fixed: binary zeroes
729     are now no different to any other data bytes.
731     (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
732     used to set a locale for matching. The --locale=xxxx long option has
733     been added (no short equivalent) to specify a locale explicitly on the
734     pcregrep command, overriding the environment variables.
736     (d) When -B was used with -n, some line numbers in the output were one less
737     than they should have been.
739     (e) Added the -o (--only-matching) option.
741     (f) If -A or -C was used with -c (count only), some lines of context were
742     accidentally printed for the final match.
744     (g) Added the -H (--with-filename) option.
746     (h) The combination of options -rh failed to suppress file names for files
747     that were found from directory arguments.
749     (i) Added the -D (--devices) and -d (--directories) options.
751     (j) Added the -F (--fixed-strings) option.
753     (k) Allow "-" to be used as a file name for -f as well as for a data file.
755     (l) Added the --colo(u)r option.
757     (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
758     is not present by default.
760     3. A nasty bug was discovered in the handling of recursive patterns, that is,
761     items such as (?R) or (?1), when the recursion could match a number of
762     alternatives. If it matched one of the alternatives, but subsequently,
763     outside the recursion, there was a failure, the code tried to back up into
764     the recursion. However, because of the way PCRE is implemented, this is not
765     possible, and the result was an incorrect result from the match.
767     In order to prevent this happening, the specification of recursion has
768     been changed so that all such subpatterns are automatically treated as
769     atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
771     4. I had overlooked the fact that, in some locales, there are characters for
772     which isalpha() is true but neither isupper() nor islower() are true. In
773     the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
774     and ordfeminine) are like this. This affected the treatment of \w and \W
775     when they appeared in character classes, but not when they appeared outside
776     a character class. The bit map for "word" characters is now created
777     separately from the results of isalnum() instead of just taking it from the
778     upper, lower, and digit maps. (Plus the underscore character, of course.)
780     5. The above bug also affected the handling of POSIX character classes such as
781     [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
782     permanent tables. Instead, the bit maps for such a class were previously
783     created as the appropriate unions of the upper, lower, and digit bitmaps.
784     Now they are created by subtraction from the [[:word:]] class, which has
785     its own bitmap.
787     6. The [[:blank:]] character class matches horizontal, but not vertical space.
788     It is created by subtracting the vertical space characters (\x09, \x0a,
789     \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
790     subtraction was done in the overall bitmap for a character class, meaning
791     that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
792     be recognized. This bug has been fixed.
794     7. Patches from the folks at Google:
796     (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
797     real life, but is still worth protecting against".
799     (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
800     regular expressions".
802     (c) pcre_scanner.cc: avoid use of std::count() because not all systems
803     have it.
805     (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
806     "configure" and the latter not, in order to fix a problem somebody had
807     with compiling the Arg class on HP-UX.
809     (e) Improve the error-handling of the C++ wrapper a little bit.
811     (f) New tests for checking recursion limiting.
813     8. The pcre_memmove() function, which is used only if the environment does not
814     have a standard memmove() function (and is therefore rarely compiled),
815     contained two bugs: (a) use of int instead of size_t, and (b) it was not
816     returning a result (though PCRE never actually uses the result).
818     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
819     large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
820     returned instead of calling malloc() with an overflowing number that would
821     most likely cause subsequent chaos.
823     10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
825     11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
826     with this option is matched, the nmatch and pmatch options of regexec() are
827     ignored.
829     12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
830     provided in case anyone wants to the the POSIX interface with UTF-8
831     strings.
833     13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
834     C++ linking (needed for some HP-UX environments).
836     14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
837     (unused parameter) and in the pcre_printint() function (omitted "default"
838     switch label when the default is to do nothing).
840     15. Added some code to make it possible, when PCRE is compiled as a C++
841     library, to replace subject pointers for pcre_exec() with a smart pointer
842     class, thus making it possible to process discontinuous strings.
844     16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
845     much the same function. They were added by different people who were trying
846     to make PCRE easy to compile on non-Unix systems. It has been suggested
847     that PCRE_EXPORT be abolished now that there is more automatic apparatus
848     for compiling on Windows systems. I have therefore replaced it with
849     PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
850     defaults to "extern" for C or "extern C" for C++, which works fine on
851     Unix-like systems. It is now possible to override the value of PCRE_DATA_
852     SCOPE with something explicit in config.h. In addition:
854     (a) pcreposix.h still had just "extern" instead of either of these macros;
855     I have replaced it with PCRE_DATA_SCOPE.
857     (b) Functions such as _pcre_xclass(), which are internal to the library,
858     but external in the C sense, all had PCRE_EXPORT in their definitions.
859     This is apparently wrong for the Windows case, so I have removed it.
860     (It makes no difference on Unix-like systems.)
862     17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
863     of recursive calls to match(). This is different to MATCH_LIMIT because
864     that limits the total number of calls to match(), not all of which increase
865     the depth of recursion. Limiting the recursion depth limits the amount of
866     stack (or heap if NO_RECURSE is set) that is used. The default can be set
867     when PCRE is compiled, and changed at run time. A patch from Google adds
868     this functionality to the C++ interface.
870     18. Changes to the handling of Unicode character properties:
872     (a) Updated the table to Unicode 4.1.0.
874     (b) Recognize characters that are not in the table as "Cn" (undefined).
876     (c) I revised the way the table is implemented to a much improved format
877     which includes recognition of ranges. It now supports the ranges that
878     are defined in UnicodeData.txt, and it also amalgamates other
879     characters into ranges. This has reduced the number of entries in the
880     table from around 16,000 to around 3,000, thus reducing its size
881     considerably. I realized I did not need to use a tree structure after
882     all - a binary chop search is just as efficient. Having reduced the
883     number of entries, I extended their size from 6 bytes to 8 bytes to
884     allow for more data.
886     (d) Added support for Unicode script names via properties such as \p{Han}.
888     19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
889     matching that character.
891     20. When matching a repeated Unicode property with a minimum greater than zero,
892     (for example \pL{2,}), PCRE could look past the end of the subject if it
893     reached it while seeking the minimum number of characters. This could
894     happen only if some of the characters were more than one byte long, because
895     there is a check for at least the minimum number of bytes.
897     21. Refactored the implementation of \p and \P so as to be more general, to
898     allow for more different types of property in future. This has changed the
899     compiled form incompatibly. Anybody with saved compiled patterns that use
900     \p or \P will have to recompile them.
902     22. Added "Any" and "L&" to the supported property types.
904     23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
905     but give a compile time error if the value is greater than 0xff.
907     24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
908     accidentally not being installed or uninstalled.
910     25. The pcre.h file was built from pcre.h.in, but the only changes that were
911     made were to insert the current release number. This seemed silly, because
912     it made things harder for people building PCRE on systems that don't run
913     "configure". I have turned pcre.h into a distributed file, no longer built
914     by "configure", with the version identification directly included. There is
915     no longer a pcre.h.in file.
917     However, this change necessitated a change to the pcre-config script as
918     well. It is built from pcre-config.in, and one of the substitutions was the
919     release number. I have updated configure.ac so that ./configure now finds
920     the release number by grepping pcre.h.
922     26. Added the ability to run the tests under valgrind.
925 nigel 85 Version 6.4 05-Sep-05
926     ---------------------
928     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
929     "--" to be printed when multiple files were scanned, even when none of the
930     -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
931     consider it to be a bug, and have restored the previous behaviour.
933     2. A couple of code tidies to get rid of compiler warnings.
935     3. The pcretest program used to cheat by referring to symbols in the library
936     whose names begin with _pcre_. These are internal symbols that are not
937     really supposed to be visible externally, and in some environments it is
938     possible to suppress them. The cheating is now confined to including
939     certain files from the library's source, which is a bit cleaner.
941     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
942     file's purpose clearer.
944     5. Reorganized pcre_ucp_findchar().
947 nigel 83 Version 6.3 15-Aug-05
948     ---------------------
950     1. The file libpcre.pc.in did not have general read permission in the tarball.
952     2. There were some problems when building without C++ support:
954     (a) If C++ support was not built, "make install" and "make test" still
955     tried to test it.
957     (b) There were problems when the value of CXX was explicitly set. Some
958     changes have been made to try to fix these, and ...
960     (c) --disable-cpp can now be used to explicitly disable C++ support.
962     (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
963     backslash in a target when C++ was disabled. This confuses some
964     versions of "make", apparently. Using an intermediate variable solves
965     this. (Same for CPP_LOBJ.)
967     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
968     (non-Windows) now includes $(CFLAGS) because these flags are sometimes
969     necessary on certain architectures.
971     4. Added a setting of -export-symbols-regex to the link command to remove
972     those symbols that are exported in the C sense, but actually are local
973     within the library, and not documented. Their names all begin with
974     "_pcre_". This is not a perfect job, because (a) we have to except some
975     symbols that pcretest ("illegally") uses, and (b) the facility isn't always
976     available (and never for static libraries). I have made a note to try to
977     find a way round (a) in the future.
980 nigel 81 Version 6.2 01-Aug-05
981     ---------------------
983     1. There was no test for integer overflow of quantifier values. A construction
984     such as {1111111111111111} would give undefined results. What is worse, if
985     a minimum quantifier for a parenthesized subpattern overflowed and became
986     negative, the calculation of the memory size went wrong. This could have
987     led to memory overwriting.
989     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
991     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
992     operating environments where this matters.
994     4. Applied Giuseppe Maxia's patch to add additional features for controlling
995     PCRE options from within the C++ wrapper.
997     5. Named capturing subpatterns were not being correctly counted when a pattern
998     was compiled. This caused two problems: (a) If there were more than 100
999     such subpatterns, the calculation of the memory needed for the whole
1000     compiled pattern went wrong, leading to an overflow error. (b) Numerical
1001     back references of the form \12, where the number was greater than 9, were
1002     not recognized as back references, even though there were sufficient
1003     previous subpatterns.
1005     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1006     versions of gcc, e.g. 2.95.4.
1009 nigel 79 Version 6.1 21-Jun-05
1010     ---------------------
1012     1. There was one reference to the variable "posix" in pcretest.c that was not
1013     surrounded by "#if !defined NOPOSIX".
1015     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1016     the cross-check on the old pcre_info() function, for the benefit of the
1017     cut-down version of PCRE that is currently imported into Exim.
1019     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1020     allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1021     patterns that start (?i) but I don't think that matters. The use of (?i) is
1022     just an example; this all applies to the other options as well.
1024     4. Since libtool seems to echo the compile commands it is issuing, the output
1025     from "make" can be reduced a bit by putting "@" in front of each libtool
1026     compile command.
1028     5. Patch from the folks at Google for configure.in to be a bit more thorough
1029     in checking for a suitable C++ installation before trying to compile the
1030     C++ stuff. This should fix a reported problem when a compiler was present,
1031     but no suitable headers.
1033     6. The man pages all had just "PCRE" as their title. I have changed them to
1034     be the relevant file name. I have also arranged that these names are
1035     retained in the file doc/pcre.txt, which is a concatenation in text format
1036     of all the man pages except the little individual ones for each function.
1038     7. The NON-UNIX-USE file had not been updated for the different set of source
1039     files that come with release 6. I also added a few comments about the C++
1040     wrapper.
1043 nigel 77 Version 6.0 07-Jun-05
1044     ---------------------
1046     1. Some minor internal re-organization to help with my DFA experiments.
1048     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1049     didn't matter for the library itself when fully configured, but did matter
1050     when compiling without UCP support, or within Exim, where the ucp files are
1051     not imported.
1053     3. Refactoring of the library code to split up the various functions into
1054     different source modules. The addition of the new DFA matching code (see
1055     below) to a single monolithic source would have made it really too
1056     unwieldy, quite apart from causing all the code to be include in a
1057     statically linked application, when only some functions are used. This is
1058     relevant even without the DFA addition now that patterns can be compiled in
1059     one application and matched in another.
1061     The downside of splitting up is that there have to be some external
1062     functions and data tables that are used internally in different modules of
1063     the library but which are not part of the API. These have all had their
1064     names changed to start with "_pcre_" so that they are unlikely to clash
1065     with other external names.
1067     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1068     a different (DFA) algorithm. Although it is slower than the original
1069     function, it does have some advantages for certain types of matching
1070     problem.
1072     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1073     including restarting after a partial match.
1075     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1076     defined when compiling for Windows was sent to me. I have put it into the
1077     code, though I have no means of testing or verifying it.
1079     7. Added the pcre_refcount() auxiliary function.
1081     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1082     match before or at the first newline in the subject string. In pcretest,
1083     the /f option on a pattern can be used to set this.
1085     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1086     would behave wrongly. This has been present in PCRE since release 4.0.
1088     10. A number of changes to the pcregrep command:
1090     (a) Refactored how -x works; insert ^(...)$ instead of setting
1091     PCRE_ANCHORED and checking the length, in preparation for adding
1092     something similar for -w.
1094     (b) Added the -w (match as a word) option.
1096     (c) Refactored the way lines are read and buffered so as to have more
1097     than one at a time available.
1099     (d) Implemented a pcregrep test script.
1101     (e) Added the -M (multiline match) option. This allows patterns to match
1102     over several lines of the subject. The buffering ensures that at least
1103     8K, or the rest of the document (whichever is the shorter) is available
1104     for matching (and similarly the previous 8K for lookbehind assertions).
1106     (f) Changed the --help output so that it now says
1108     -w, --word-regex(p)
1110     instead of two lines, one with "regex" and the other with "regexp"
1111     because that confused at least one person since the short forms are the
1112     same. (This required a bit of code, as the output is generated
1113     automatically from a table. It wasn't just a text change.)
1115     (g) -- can be used to terminate pcregrep options if the next thing isn't an
1116     option but starts with a hyphen. Could be a pattern or a path name
1117     starting with a hyphen, for instance.
1119     (h) "-" can be given as a file name to represent stdin.
1121     (i) When file names are being printed, "(standard input)" is used for
1122     the standard input, for compatibility with GNU grep. Previously
1123     "<stdin>" was used.
1125     (j) The option --label=xxx can be used to supply a name to be used for
1126     stdin when file names are being printed. There is no short form.
1128     (k) Re-factored the options decoding logic because we are going to add
1129     two more options that take data. Such options can now be given in four
1130     different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1132     (l) Added the -A, -B, and -C options for requesting that lines of context
1133     around matches be printed.
1135     (m) Added the -L option to print the names of files that do not contain
1136     any matching lines, that is, the complement of -l.
1138     (n) The return code is 2 if any file cannot be opened, but pcregrep does
1139     continue to scan other files.
1141     (o) The -s option was incorrectly implemented. For compatibility with other
1142     greps, it now suppresses the error message for a non-existent or non-
1143     accessible file (but not the return code). There is a new option called
1144     -q that suppresses the output of matching lines, which was what -s was
1145     previously doing.
1147     (p) Added --include and --exclude options to specify files for inclusion
1148     and exclusion when recursing.
1150     11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1151     Hopefully, it now does.
1153     12. Missing cast in pcre_study().
1155     13. Added an "uninstall" target to the makefile.
1157     14. Replaced "extern" in the function prototypes in Makefile.in with
1158     "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1159     world, but is set differently for Windows.
1161     15. Added a second compiling function called pcre_compile2(). The only
1162     difference is that it has an extra argument, which is a pointer to an
1163     integer error code. When there is a compile-time failure, this is set
1164     non-zero, in addition to the error test pointer being set to point to an
1165     error message. The new argument may be NULL if no error number is required
1166     (but then you may as well call pcre_compile(), which is now just a
1167     wrapper). This facility is provided because some applications need a
1168     numeric error indication, but it has also enabled me to tidy up the way
1169     compile-time errors are handled in the POSIX wrapper.
1171     16. Added VPATH=.libs to the makefile; this should help when building with one
1172     prefix path and installing with another. (Or so I'm told by someone who
1173     knows more about this stuff than I do.)
1175     17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1176     passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1177     match everything, including newlines. This is not POSIX-compatible, but
1178     somebody wanted the feature. From pcretest it can be activated by using
1179     both the P and the s flags.
1181     18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1183     19. libpcre.pc was being incorrectly installed as executable.
1185     20. A couple of places in pcretest check for end-of-line by looking for '\n';
1186     it now also looks for '\r' so that it will work unmodified on Windows.
1188     21. Added Google's contributed C++ wrapper to the distribution.
1190     22. Added some untidy missing memory free() calls in pcretest, to keep
1191     Electric Fence happy when testing.
1195 nigel 75 Version 5.0 13-Sep-04
1196     ---------------------
1198     1. Internal change: literal characters are no longer packed up into items
1199     containing multiple characters in a single byte-string. Each character
1200     is now matched using a separate opcode. However, there may be more than one
1201     byte in the character in UTF-8 mode.
1203     2. The pcre_callout_block structure has two new fields: pattern_position and
1204     next_item_length. These contain the offset in the pattern to the next match
1205     item, and its length, respectively.
1207     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1208     insertion of callouts before each pattern item. Added the /C option to
1209     pcretest to make use of this.
1211     4. On the advice of a Windows user, the lines
1213     #if defined(_WIN32) || defined(WIN32)
1214     _setmode( _fileno( stdout ), 0x8000 );
1215     #endif /* defined(_WIN32) || defined(WIN32) */
1217     have been added to the source of pcretest. This apparently does useful
1218     magic in relation to line terminators.
1220     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1221     for the benefit of those environments where the "b" makes a difference.
1223     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1224     to know about it. I have put a hack into configure.in that adds in code
1225     to set GCC=yes if CC=icc. This seems to end up at a point in the
1226     generated configure script that is early enough to affect the setting of
1227     compiler options, which is what is needed, but I have no means of testing
1228     whether it really works. (The user who reported this had patched the
1229     generated configure script, which of course I cannot do.)
1231     LATER: After change 22 below (new libtool files), the configure script
1232     seems to know about icc (and also ecc). Therefore, I have commented out
1233     this hack in configure.in.
1235     7. Added support for pkg-config (2 patches were sent in).
1237     8. Negated POSIX character classes that used a combination of internal tables
1238     were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1239     [[:^ascii]]. Typically, they would match almost any characters. The other
1240     POSIX classes were not broken in this way.
1242     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1243     to find the match, as PCRE was deluded into thinking that the match had to
1244     start at the start point or following a newline. The same bug applied to
1245     patterns with negative forward assertions or any backward assertions
1246     preceding ".*" at the start, unless the pattern required a fixed first
1247     character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1249     10. In UTF-8 mode, when moving forwards in the subject after a failed match
1250     starting at the last subject character, bytes beyond the end of the subject
1251     string were read.
1253     11. Renamed the variable "class" as "classbits" to make life easier for C++
1254     users. (Previously there was a macro definition, but it apparently wasn't
1255     enough.)
1257     12. Added the new field "tables" to the extra data so that tables can be passed
1258     in at exec time, or the internal tables can be re-selected. This allows
1259     a compiled regex to be saved and re-used at a later time by a different
1260     program that might have everything at different addresses.
1262     13. Modified the pcre-config script so that, when run on Solaris, it shows a
1263     -R library as well as a -L library.
1265     14. The debugging options of pcretest (-d on the command line or D on a
1266     pattern) showed incorrect output for anything following an extended class
1267     that contained multibyte characters and which was followed by a quantifier.
1269     15. Added optional support for general category Unicode character properties
1270     via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1271     support. It adds about 90K to the size of the library. The meanings of the
1272     inbuilt class escapes such as \d and \s have NOT been changed.
1274     16. Updated pcredemo.c to include calls to free() to release the memory for the
1275     compiled pattern.
1277     17. The generated file chartables.c was being created in the source directory
1278     instead of in the building directory. This caused the build to fail if the
1279     source directory was different from the building directory, and was
1280     read-only.
1282     18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1283     file. No doubt somebody will tell me if they don't make sense... Also added
1284     Dan Mooney's comments about building on OpenVMS.
1286     19. Added support for partial matching via the PCRE_PARTIAL option for
1287     pcre_exec() and the \P data escape in pcretest.
1289     20. Extended pcretest with 3 new pattern features:
1291     (i) A pattern option of the form ">rest-of-line" causes pcretest to
1292     write the compiled pattern to the file whose name is "rest-of-line".
1293     This is a straight binary dump of the data, with the saved pointer to
1294     the character tables forced to be NULL. The study data, if any, is
1295     written too. After writing, pcretest reads a new pattern.
1297     (ii) If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1298     compiled pattern from the given file. There must not be any
1299     occurrences of "<" in the file name (pretty unlikely); if there are,
1300     pcretest will instead treat the initial "<" as a pattern delimiter.
1301     After reading in the pattern, pcretest goes on to read data lines as
1302     usual.
1304     (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1305     and 16-bit fields in a compiled pattern, to simulate a pattern that
1306     was compiled on a host of opposite endianness.
1308     21. The pcre-exec() function can now cope with patterns that were compiled on
1309     hosts of opposite endianness, with this restriction:
1311     As for any compiled expression that is saved and used later, the tables
1312     pointer field cannot be preserved; the extra_data field in the arguments
1313     to pcre_exec() should be used to pass in a tables address if a value
1314     other than the default internal tables were used at compile time.
1316     22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1317     now diagnosed as an error. Previously, most of the time, a negative number
1318     would have been treated as zero, but if in addition "ovector" was passed as
1319     NULL, a crash could occur.
1321     23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1322     new versions from the libtool 1.5 distribution (the last one is a copy of
1323     a file called libtool.m4). This seems to have fixed the need to patch
1324     "configure" to support Darwin 1.3 (which I used to do). However, I still
1325     had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1326     workstation).
1328     24. Changed the PCRE licence to be the more standard "BSD" licence.
1331 nigel 73 Version 4.5 01-Dec-03
1332     ---------------------
1334     1. There has been some re-arrangement of the code for the match() function so
1335     that it can be compiled in a version that does not call itself recursively.
1336     Instead, it keeps those local variables that need separate instances for
1337     each "recursion" in a frame on the heap, and gets/frees frames whenever it
1338     needs to "recurse". Keeping track of where control must go is done by means
1339     of setjmp/longjmp. The whole thing is implemented by a set of macros that
1340     hide most of the details from the main code, and operates only if
1341     NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1342     "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1343     operating.
1345     To make it easier for callers to provide specially tailored get/free
1346     functions for this usage, two new functions, pcre_stack_malloc, and
1347     pcre_stack_free, are used. They are always called in strict stacking order,
1348     and the size of block requested is always the same.
1350     The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1351     PCRE has been compiled to use the stack or the heap for recursion. The
1352     -C option of pcretest uses this to show which version is compiled.
1354     A new data escape \S, is added to pcretest; it causes the amounts of store
1355     obtained and freed by both kinds of malloc/free at match time to be added
1356     to the output.
1358     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1359     what's available on my current Linux desktop machine.
1361     3. When matching a UTF-8 string, the test for a valid string at the start has
1362     been extended. If start_offset is not zero, PCRE now checks that it points
1363     to a byte that is the start of a UTF-8 character. If not, it returns
1364     PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1365     this is necessary because there may be backward assertions in the pattern.
1366     When matching the same subject several times, it may save resources to use
1367     PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1369     4. The code for checking the validity of UTF-8 strings has been tightened so
1370     that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1371     containing "overlong sequences".
1373     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1374     I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1375     should have been "&", but it just so happened that all the cases this let
1376     through by mistake were picked up later in the function.
1378     6. I had used a variable called "isblank" - this is a C99 function, causing
1379     some compilers to warn. To avoid this, I renamed it (as "blankclass").
1381     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1382     prompting; (b) run "./pcretest /dev/null" at the start of the test script
1383     so the version is shown; (c) stop "make test" echoing "./RunTest".
1385     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1387     9. The prototype for memmove() for systems that don't have it was using
1388     size_t, but the inclusion of the header that defines size_t was later. I've
1389     moved the #includes for the C headers earlier to avoid this.
1391     10. Added some adjustments to the code to make it easier to compiler on certain
1392     special systems:
1394     (a) Some "const" qualifiers were missing.
1395     (b) Added the macro EXPORT before all exported functions; by default this
1396     is defined to be empty.
1397     (c) Changed the dftables auxiliary program (that builds chartables.c) so
1398     that it reads its output file name as an argument instead of writing
1399     to the standard output and assuming this can be redirected.
1401     11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1402     class containing characters with values greater than 255, PCRE compilation
1403     went into a loop.
1405     12. A recursive reference to a subpattern that was within another subpattern
1406     that had a minimum quantifier of zero caused PCRE to crash. For example,
1407     (x(y(?2))z)? provoked this bug with a subject that got as far as the
1408     recursion. If the recursively-called subpattern itself had a zero repeat,
1409     that was OK.
1411     13. In pcretest, the buffer for reading a data line was set at 30K, but the
1412     buffer into which it was copied (for escape processing) was still set at
1413     1024, so long lines caused crashes.
1415     14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1416     "internal error: code overflow...". This applied to any character class
1417     that was followed by a possessive quantifier.
1419     15. Modified the Makefile to add libpcre.la as a prerequisite for
1420     libpcreposix.la because I was told this is needed for a parallel build to
1421     work.
1423     16. If a pattern that contained .* following optional items at the start was
1424     studied, the wrong optimizing data was generated, leading to matching
1425     errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1426     matching string must start with a or b or c. The correct conclusion for
1427     this pattern is that a match can start with any character.
1430 nigel 71 Version 4.4 13-Aug-03
1431     ---------------------
1433     1. In UTF-8 mode, a character class containing characters with values between
1434     127 and 255 was not handled correctly if the compiled pattern was studied.
1435     In fixing this, I have also improved the studying algorithm for such
1436     classes (slightly).
1438     2. Three internal functions had redundant arguments passed to them. Removal
1439     might give a very teeny performance improvement.
1441     3. Documentation bug: the value of the capture_top field in a callout is *one
1442     more than* the number of the hightest numbered captured substring.
1444     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1445     in incorrectly linking with a previously installed version. They now link
1446     explicitly with libpcre.la.
1448     5. configure.in no longer needs to recognize Cygwin specially.
1450     6. A problem in pcre.in for Windows platforms is fixed.
1452     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1453     pcretest, it used to include the size of the study block as part of its
1454     output. Unfortunately, the structure contains a field that has a different
1455     size on different hardware architectures. This meant that the tests that
1456     showed this size failed. As the block is currently always of a fixed size,
1457     this information isn't actually particularly useful in pcretest output, so
1458     I have just removed it.
1460     8. Three pre-processor statements accidentally did not start in column 1.
1461     Sadly, there are *still* compilers around that complain, even though
1462     standard C has not required this for well over a decade. Sigh.
1464     9. In pcretest, the code for checking callouts passed small integers in the
1465     callout_data field, which is a void * field. However, some picky compilers
1466     complained about the casts involved for this on 64-bit systems. Now
1467     pcretest passes the address of the small integer instead, which should get
1468     rid of the warnings.
1470     10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1471     both compile and run time, and gives an error if an invalid UTF-8 sequence
1472     is found. There is a option for disabling this check in cases where the
1473     string is known to be correct and/or the maximum performance is wanted.
1475     11. In response to a bug report, I changed one line in Makefile.in from
1477     -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1478     to
1479     -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1481     to look similar to other lines, but I have no way of telling whether this
1482     is the right thing to do, as I do not use Windows. No doubt I'll get told
1483     if it's wrong...
1486 nigel 69 Version 4.3 21-May-03
1487     ---------------------
1489     1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1490     Makefile.
1492     2. Some refactoring to improve the quality of the code:
1494     (i) The utf8_table... variables are now declared "const".
1496     (ii) The code for \cx, which used the "case flipping" table to upper case
1497     lower case letters, now just substracts 32. This is ASCII-specific,
1498     but the whole concept of \cx is ASCII-specific, so it seems
1499     reasonable.
1501     (iii) PCRE was using its character types table to recognize decimal and
1502     hexadecimal digits in the pattern. This is silly, because it handles
1503     only 0-9, a-f, and A-F, but the character types table is locale-
1504     specific, which means strange things might happen. A private
1505     table is now used for this - though it costs 256 bytes, a table is
1506     much faster than multiple explicit tests. Of course, the standard
1507     character types table is still used for matching digits in subject
1508     strings against \d.
1510     (iv) Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1511     ending in _t are). So I've renamed it as ESC_tee.
1513     3. The first argument for regexec() in the POSIX wrapper should have been
1514     defined as "const".
1516     4. Changed pcretest to use malloc() for its buffers so that they can be
1517     Electric Fenced for debugging.
1519     5. There were several places in the code where, in UTF-8 mode, PCRE would try
1520     to read one or more bytes before the start of the subject string. Often this
1521     had no effect on PCRE's behaviour, but in some circumstances it could
1522     provoke a segmentation fault.
1524     6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1525     to try to read one or more bytes before the start of the subject string.
1527     7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1528     UTF-8 support could misbehave in various ways if the subject string
1529     contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1530     area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1531     back over UTF-8 characters.)
1534 nigel 67 Version 4.2 14-Apr-03
1535     ---------------------
1537     1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1539     2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1540     [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1541     [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1542     [WIN_PREFIX]: new variable, "cyg" for Cygwin
1543     * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1544     and BUILD_EXEEXT
1545     Note: automatic setting of the BUILD variables is not yet working
1546     set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1547     compile-time but not at link-time
1548     [LINK]: use for linking executables only
1549     make different versions for Windows and non-Windows
1550     [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1551     libraries
1552     [LINK_FOR_BUILD]: new variable
1553     [OBJEXT]: use throughout
1554     [EXEEXT]: use throughout
1555     <winshared>: new target
1556     <wininstall>: new target
1557     <dftables.o>: use native compiler
1558     <dftables>: use native linker
1559     <install>: handle Windows platform correctly
1560     <clean>: ditto
1561     <check>: ditto
1562     copy DLL to top builddir before testing
1564     As part of these changes, -no-undefined was removed again. This was reported
1565     to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1566     in any case.
1568     3. Some tidies to get rid of compiler warnings:
1570     . In the match_data structure, match_limit was an unsigned long int, whereas
1571     match_call_count was an int. I've made them both unsigned long ints.
1573     . In pcretest the fact that a const uschar * doesn't automatically cast to
1574     a void * provoked a warning.
1576     . Turning on some more compiler warnings threw up some "shadow" variables
1577     and a few more missing casts.
1579     4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1580     option, a class that contained a single character with a value between 128
1581     and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1583     5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1584     option, a class that contained several characters, but with at least one
1585     whose value was between 128 and 255 caused PCRE to crash.
1588 nigel 65 Version 4.1 12-Mar-03
1589     ---------------------
1590 nigel 63
1591 nigel 65 1. Compiling with gcc -pedantic found a couple of places where casts were
1592     needed, and a string in dftables.c that was longer than standard compilers are
1593     required to support.
1595     2. Compiling with Sun's compiler found a few more places where the code could
1596     be tidied up in order to avoid warnings.
1598     3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1599     first of these names is deprecated in the latest Autoconf in favour of the name
1600     CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1601     compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1602     analogy I have changed it to CFLAGS_FOR_BUILD.
1604     4. Added -no-undefined to the linking command in the Makefile, because this is
1605     apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1606     linking step for the pcreposix library.
1608     5. PCRE was failing to diagnose the case of two named groups with the same
1609     name.
1611     6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1612     literal character that is needed in the subject for a match, and scans along to
1613     ensure that it is present before embarking on the full matching process. This
1614     saves time in cases of nested unlimited repeats that are never going to match.
1615     Problem: the scan can take a lot of time if the subject is very long (e.g.
1616     megabytes), thus penalizing straightforward matches. It is now done only if the
1617     amount of subject to be scanned is less than 1000 bytes.
1619     7. A lesser problem with the same optimization is that it was recording the
1620     first character of an anchored pattern as "needed", thus provoking a search
1621     right along the subject, even when the first match of the pattern was going to
1622     fail. The "needed" character is now not set for anchored patterns, unless it
1623     follows something in the pattern that is of non-fixed length. Thus, it still
1624     fulfils its original purpose of finding quick non-matches in cases of nested
1625     unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1628     Version 4.0 17-Feb-03
1629     ---------------------
1631 nigel 63 1. If a comment in an extended regex that started immediately after a meta-item
1632     extended to the end of string, PCRE compiled incorrect data. This could lead to
1633     all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1635     2. Moved to autoconf 2.53 and libtool 1.4.2.
1637     3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1638     the special perltest8 script is no longer needed - all the tests can be run
1639     from a single perltest script.
1641     4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1642     by \s. It has now been removed in PCRE. This means it isn't recognized as
1643     whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1644     class [:space:] *does* include VT, thereby creating a mess.
1646     5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1647     space and tab.
1649     6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1650     its new features into the main test script, reducing the number of scripts.
1652     7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1653     were backward compatible, and made the (?i) apply to the whole pattern, as if
1654     /i were given. Now it behaves more logically, and applies the option setting
1655     only to what follows. PCRE has been changed to follow suit. However, if it
1656     finds options settings right at the start of the pattern, it extracts them into
1657     the global options, as before. Thus, they show up in the info data.
1659     8. Added support for the \Q...\E escape sequence. Characters in between are
1660     treated as literals. This is slightly different from Perl in that $ and @ are
1661     also handled as literals inside the quotes. In Perl, they will cause variable
1662     interpolation. Note the following examples:
1664     Pattern PCRE matches Perl matches
1666     \Qabc$xyz\E abc$xyz abc followed by the contents of $xyz
1667     \Qabc\$xyz\E abc\$xyz abc\$xyz
1668     \Qabc\E\$\Qxyz\E abc$xyz abc$xyz
1670     For compatibility with Perl, \Q...\E sequences are recognized inside character
1671     classes as well as outside them.
1673     9. Re-organized 3 code statements in pcretest to avoid "overflow in
1674     floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1675     (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1676     signed/unsigned warnings.
1678     10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1679     option for pcretest, so I've replaced it by a simple function that does just
1680     that job.
1682     11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1683     "pcregrep -".
1685     12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1686     Java package. This provides some syntactic sugar for simple cases of what my
1687     documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1688     as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1689     item, you can use this simplified notation. Note that only makes sense with
1690     greedy quantifiers. Consequently, the use of the possessive quantifier forces
1691     greediness, whatever the setting of the PCRE_UNGREEDY option.
1693     13. A change of greediness default within a pattern was not taking effect at
1694     the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1695     subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1696     was abstracted outside.
1698     14. PCRE now supports the \G assertion. It is true when the current matching
1699     position is at the start point of the match. This differs from \A when the
1700     starting offset is non-zero. Used with the /g option of pcretest (or similar
1701     code), it works in the same way as it does for Perl's /g option. If all
1702     alternatives of a regex begin with \G, the expression is anchored to the start
1703     match position, and the "anchored" flag is set in the compiled expression.
1705     15. Some bugs concerning the handling of certain option changes within patterns
1706     have been fixed. These applied to options other than (?ims). For example,
1707     "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1708     been the other way round. Some of this was related to change 7 above.
1710     16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1711     features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1712     and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1713     POSIX classes only within a class (e.g. /[[:alpha:]]/).
1715     17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1716     mode. Unlike ".", it always matches newline, whatever the setting of
1717     PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1718     assertions. Perl allows it, but it doesn't (in general) work because it can't
1719     calculate the length of the lookbehind. At least, that's the case for Perl
1720     5.8.0 - I've been told they are going to document that it doesn't work in
1721     future.
1723     18. Added an error diagnosis for escapes that PCRE does not support: these are
1724     \L, \l, \N, \P, \p, \U, \u, and \X.
1726     19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1727     reading past the end of the pattern in cases such as /[abcd/.
1729     20. PCRE was getting more memory than necessary for patterns with classes that
1730     contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1732     21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1733     compiling PCRE for use with Virtual Pascal.
1735     22. Small fix to the Makefile to make it work properly if the build is done
1736     outside the source tree.
1738     23. Added a new extension: a condition to go with recursion. If a conditional
1739     subpattern starts with (?(R) the "true" branch is used if recursion has
1740     happened, whereas the "false" branch is used only at the top level.
1742     24. When there was a very long string of literal characters (over 255 bytes
1743     without UTF support, over 250 bytes with UTF support), the computation of how
1744     much memory was required could be incorrect, leading to segfaults or other
1745     strange effects.
1747     25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1748     start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1749     there was a subsequent back reference to those brackets. This meant that, for
1750     example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1751     possible to check for precisely this case. All we can do is abandon the
1752     optimization if .* occurs inside capturing brackets when there are any back
1753     references whatsoever. (See below for a better fix that came later.)
1755     26. The handling of the optimization for finding the first character of a
1756     non-anchored pattern, and for finding a character that is required later in the
1757     match were failing in some cases. This didn't break the matching; it just
1758     failed to optimize when it could. The way this is done has been re-implemented.
1760     27. Fixed typo in error message for invalid (?R item (it said "(?p").
1762     28. Added a new feature that provides some of the functionality that Perl
1763     provides with (?{...}). The facility is termed a "callout". The way it is done
1764     in PCRE is for the caller to provide an optional function, by setting
1765     pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1766     global variable. By default it is unset, which disables all calling out. To get
1767     the function called, the regex must include (?C) at appropriate points. This
1768     is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1769     This provides a means of identifying different callout points. When PCRE
1770     reaches such a point in the regex, if pcre_callout has been set, the external
1771     function is called. It is provided with data in a structure called
1772     pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1773     matching continues; if it returns a non-zero value, the match at the current
1774     point fails. However, backtracking will occur if possible. [This was changed
1775     later and other features added - see item 49 below.]
1777     29. pcretest is upgraded to test the callout functionality. It provides a
1778     callout function that displays information. By default, it shows the start of
1779     the match and the current position in the text. There are some new data escapes
1780     to vary what happens:
1782     \C+ in addition, show current contents of captured substrings
1783     \C- do not supply a callout function
1784     \C!n return 1 when callout number n is reached
1785     \C!n!m return 1 when callout number n is reached for the mth time
1787     30. If pcregrep was called with the -l option and just a single file name, it
1788     output "<stdin>" if a match was found, instead of the file name.
1790     31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1791     slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1792     pcre_exec(). This saves a malloc/free per call. The default value of
1793     POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1794     when configuring.
1796     32. The default maximum size of a compiled pattern is 64K. There have been a
1797     few cases of people hitting this limit. The code now uses macros to handle the
1798     storing of links as offsets within the compiled pattern. It defaults to 2-byte
1799     links, but this can be changed to 3 or 4 bytes by --with-link-size when
1800     configuring. Tests 2 and 5 work only with 2-byte links because they output
1801     debugging information about compiled patterns.
1803     33. Internal code re-arrangements:
1805     (a) Moved the debugging function for printing out a compiled regex into
1806     its own source file (printint.c) and used #include to pull it into
1807     pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1808     separate copies.
1810     (b) Defined the list of op-code names for debugging as a macro in
1811     internal.h so that it is next to the definition of the opcodes.
1813     (c) Defined a table of op-code lengths for simpler skipping along compiled
1814     code. This is again a macro in internal.h so that it is next to the
1815     definition of the opcodes.
1817     34. Added support for recursive calls to individual subpatterns, along the
1818     lines of Robin Houston's patch (but implemented somewhat differently).
1820     35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1821     allow it to read and process whole directories in Win32. This code was
1822     contributed by Lionel Fourquaux; it has not been tested by me.
1824     36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1825     used to name a group. Names consist of alphanumerics and underscores, and must
1826     be unique. Back references use the syntax (?P=name) and recursive calls use
1827     (?P>name) which is a PCRE extension to the Python extension. Groups still have
1828     numbers. The function pcre_fullinfo() can be used after compilation to extract
1829     a name/number map. There are three relevant calls:
1831     PCRE_INFO_NAMEENTRYSIZE yields the size of each entry in the map
1832     PCRE_INFO_NAMECOUNT yields the number of entries
1833     PCRE_INFO_NAMETABLE yields a pointer to the map.
1835     The map is a vector of fixed-size entries. The size of each entry depends on
1836     the length of the longest name used. The first two bytes of each entry are the
1837     group number, most significant byte first. There follows the corresponding
1838     name, zero terminated. The names are in alphabetical order.
1840     37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1841     case instead of 255. Making it the same both with and without UTF-8 support
1842     means that the same test output works with both.
1844     38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1845     calling malloc() with a zero argument.
1847     39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1848     optimization. I've improved things by keeping a bitmap of backreferences with
1849     numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1850     fact referenced, the optimization can be applied. It is unlikely that a
1851     relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1852     the match to follow \n) will appear inside brackets with a number greater than
1853     31, but if it does, any back reference > 31 suppresses the optimization.
1855     40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1856     of disabling numbered capturing parentheses. Any opening parenthesis that is
1857     not followed by ? behaves as if it were followed by ?: but named parentheses
1858     can still be used for capturing (and they will acquire numbers in the usual
1859     way).
1861     41. Redesigned the return codes from the match() function into yes/no/error so
1862     that errors can be passed back from deep inside the nested calls. A malloc
1863     failure while inside a recursive subpattern call now causes the
1864     PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1866     42. It is now possible to set a limit on the number of times the match()
1867     function is called in a call to pcre_exec(). This facility makes it possible to
1868     limit the amount of recursion and backtracking, though not in a directly
1869     obvious way, because the match() function is used in a number of different
1870     circumstances. The count starts from zero for each position in the subject
1871     string (for non-anchored patterns). The default limit is, for compatibility, a
1872     large number, namely 10 000 000. You can change this in two ways:
1874     (a) When configuring PCRE before making, you can use --with-match-limit=n
1875     to set a default value for the compiled library.
1877     (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1878     a different value is set. See 45 below.
1880     If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1882     43. Added a new function pcre_config(int, void *) to enable run-time extraction
1883     of things that can be changed at compile time. The first argument specifies
1884     what is wanted and the second points to where the information is to be placed.
1885     The current list of available information is:
1889     The output is an integer that is set to one if UTF-8 support is available;
1890     otherwise it is set to zero.
1894     The output is an integer that it set to the value of the code that is used for
1895     newline. It is either LF (10) or CR (13).
1899     The output is an integer that contains the number of bytes used for internal
1900     linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1904     The output is an integer that contains the threshold above which the POSIX
1905     interface uses malloc() for output vectors. See item 31 above.
1909     The output is an unsigned integer that contains the default limit of the number
1910     of match() calls in a pcre_exec() execution. See 42 above.
1912     44. pcretest has been upgraded by the addition of the -C option. This causes it
1913     to extract all the available output from the new pcre_config() function, and to
1914     output it. The program then exits immediately.
1916     45. A need has arisen to pass over additional data with calls to pcre_exec() in
1917     order to support additional features. One way would have been to define
1918     pcre_exec2() (for example) with extra arguments, but this would not have been
1919     extensible, and would also have required all calls to the original function to
1920     be mapped to the new one. Instead, I have chosen to extend the mechanism that
1921     is used for passing in "extra" data from pcre_study().
1923     The pcre_extra structure is now exposed and defined in pcre.h. It currently
1924     contains the following fields:
1926     flags a bitmap indicating which of the following fields are set
1927     study_data opaque data from pcre_study()
1928     match_limit a way of specifying a limit on match() calls for a specific
1929     call to pcre_exec()
1930     callout_data data for callouts (see 49 below)
1932     The flag bits are also defined in pcre.h, and are
1938     The pcre_study() function now returns one of these new pcre_extra blocks, with
1939     the actual study data pointed to by the study_data field, and the
1940     PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1941     before. That is, this change is entirely upwards-compatible and requires no
1942     change to existing code.
1944     If you want to pass in additional data to pcre_exec(), you can either place it
1945     in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1946     block.
1948     46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1949     data string contains the escape sequence \M, pcretest calls pcre_exec() several
1950     times with different match limits, until it finds the minimum value needed for
1951     pcre_exec() to complete. The value is then output. This can be instructive; for
1952     most simple matches the number is quite small, but for pathological cases it
1953     gets very large very quickly.
1955     47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1956     returns the size of the data block pointed to by the study_data field in a
1957     pcre_extra block, that is, the value that was passed as the argument to
1958     pcre_malloc() when PCRE was getting memory in which to place the information
1959     created by pcre_study(). The fourth argument should point to a size_t variable.
1960     pcretest has been extended so that this information is shown after a successful
1961     pcre_study() call when information about the compiled regex is being displayed.
1963     48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1964     because what follows is always an absolute path. (Later: it turns out that this
1965     is more than cosmetic for MinGW, because it doesn't like empty path
1966     components.)
1968     49. Some changes have been made to the callout feature (see 28 above):
1970     (i) A callout function now has three choices for what it returns:
1972     0 => success, carry on matching
1973     > 0 => failure at this point, but backtrack if possible
1974     < 0 => serious error, return this value from pcre_exec()
1976     Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1977     values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1978     "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1979     use by callout functions. It will never be used by PCRE itself.
1981     (ii) The pcre_extra structure (see 45 above) has a void * field called
1982     callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1983     pcre_callout_block structure has a field of the same name. The contents of
1984     the field passed in the pcre_extra structure are passed to the callout
1985     function in the corresponding field in the callout block. This makes it
1986     easier to use the same callout-containing regex from multiple threads. For
1987     testing, the pcretest program has a new data escape
1989     \C*n pass the number n (may be negative) as callout_data
1991     If the callout function in pcretest receives a non-zero value as
1992     callout_data, it returns that value.
1994     50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1995     there were some redundant $(CFLAGS) in commands that are now specified as
1996     $(LINK), which already includes $(CFLAGS).
1998     51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1999     has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2000     with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2001     one-byte characters throughout. Note that case-insensitive matching applies
2002     only to characters whose values are less than 256. PCRE doesn't support the
2003     notion of cases for higher-valued characters.
2005     (i) A character class whose characters are all within 0-255 is handled as
2006     a bit map, and the map is inverted for negative classes. Previously, a
2007     character > 255 always failed to match such a class; however it should
2008     match if the class was a negative one (e.g. [^ab]). This has been fixed.
2010     (ii) A negated character class with a single character < 255 is coded as
2011     "not this character" (OP_NOT). This wasn't working properly when the test
2012     character was multibyte, either singly or repeated.
2014     (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2015     mode, for example: \x{100}{2,3}.
2017     (iv) The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2018     singly or repeated) now correctly test multibyte characters. However,
2019     PCRE doesn't recognize any characters with values greater than 255 as
2020     digits, spaces, or word characters. Such characters always match \D, \S,
2021     and \W, and never match \d, \s, or \w.
2023     (v) Classes may now contain characters and character ranges with values
2024     greater than 255. For example: [ab\x{100}-\x{400}].
2026     (vi) pcregrep now has a --utf-8 option (synonym -u) which makes it call
2027     PCRE in UTF-8 mode.
2029     52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2030     PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2031     retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2032     value.)
2034     53. The single man page has become too large. I have therefore split it up into
2035     a number of separate man pages. These also give rise to individual HTML pages;
2036     these are now put in a separate directory, and there is an index.html page that
2037     lists them all. Some hyperlinking between the pages has been installed.
2039     54. Added convenience functions for handling named capturing parentheses.
2041     55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2042     aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2043     true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2044     are faulted.
2046     56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2047     calling configure. These values are used when compiling the dftables.c program
2048     which is run to generate the source of the default character tables. They
2049     default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2050     you will need to set these values.
2052     57. Updated the building process for Windows DLL, as provided by Fred Cox.
2055     Version 3.9 02-Jan-02
2056 nigel 61 ---------------------
2058     1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2060     2. If --disable-static was given, the building process failed when trying to
2061     build pcretest and pcregrep. (For some reason it was using libtool to compile
2062     them, which is not right, as they aren't part of the library.)
2065 nigel 59 Version 3.8 18-Dec-01
2066     ---------------------
2068     1. The experimental UTF-8 code was completely screwed up. It was packing the
2069     bytes in the wrong order. How dumb can you get?
2072 nigel 57 Version 3.7 29-Oct-01
2073     ---------------------
2075     1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2076     This caused pcretest, when used on the test data, to segfault. Unfortunately,
2077     this didn't happen under Solaris 8, where I normally test things.
2079 nigel 59 2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2080     doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2081     isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2082     this fix an hour or so after the initial 3.7 release.)
2083 nigel 57
2084 nigel 59
2085 nigel 55 Version 3.6 23-Oct-01
2086     ---------------------
2088     1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2089     offsets passed as NULL with zero offset count.
2091     2. The config.guess and config.sub files had not been updated when I moved to
2092     the latest autoconf.
2095 nigel 53 Version 3.5 15-Aug-01
2096     ---------------------
2097 nigel 5
2098 nigel 53 1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2099     had been forgotten.
2101     2. By using declared but undefined structures, we can avoid using "void"
2102     definitions in pcre.h while keeping the internal definitions of the structures
2103     private.
2105     3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2106     user point of view, this means that both static and shared libraries are built
2107     by default, but this can be individually controlled. More of the work of
2108     handling this static/shared cases is now inside libtool instead of PCRE's make
2109     file.
2111     4. The pcretest utility is now installed along with pcregrep because it is
2112     useful for users (to test regexs) and by doing this, it automatically gets
2113     relinked by libtool. The documentation has been turned into a man page, so
2114     there are now .1, .txt, and .html versions in /doc.
2116     5. Upgrades to pcregrep:
2117     (i) Added long-form option names like gnu grep.
2118     (ii) Added --help to list all options with an explanatory phrase.
2119     (iii) Added -r, --recursive to recurse into sub-directories.
2120     (iv) Added -f, --file to read patterns from a file.
2122     6. pcre_exec() was referring to its "code" argument before testing that
2123     argument for NULL (and giving an error if it was NULL).
2125     7. Upgraded Makefile.in to allow for compiling in a different directory from
2126     the source directory.
2128     8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2129     options bits, the pointer it was passed was to an int instead of to an unsigned
2130     long int. This mattered only on 64-bit systems.
2132     9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2133     generated) instead of pcre.in, which it its source. Also made the same change
2134     in several of the .c files.
2136     10. A new release of gcc defines printf() as a macro, which broke pcretest
2137     because it had an ifdef in the middle of a string argument for printf(). Fixed
2138     by using separate calls to printf().
2140     11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2141     script, to force use of CR or LF instead of \n in the source. On non-Unix
2142     systems, the value can be set in config.h.
2144     12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2145     absolute limit. Changed the text of the error message to make this clear, and
2146     likewise updated the man page.
2148     13. The limit of 99 on the number of capturing subpatterns has been removed.
2149     The new limit is 65535, which I hope will not be a "real" limit.
2152 nigel 51 Version 3.4 22-Aug-00
2153     ---------------------
2155     1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2157     2. Diagnose condition (?(0) as an error instead of crashing on matching.
2160 nigel 49 Version 3.3 01-Aug-00
2161     ---------------------
2163     1. If an octal character was given, but the value was greater than \377, it
2164     was not getting masked to the least significant bits, as documented. This could
2165     lead to crashes in some systems.
2167     2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2168     the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2170     3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2171     These just pass their arguments on to (pcre_free)(), but they are provided
2172     because some uses of PCRE bind it to non-C systems that can call its functions,
2173     but cannot call free() or pcre_free() directly.
2175     4. Add "make test" as a synonym for "make check". Corrected some comments in
2176     the Makefile.
2178     5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2179     Makefile.
2181     6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2182     command called pgrep for grepping around the active processes.
2184     7. Added the beginnings of support for UTF-8 character strings.
2186     8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2187     RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2188     the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2189     out for the ar command.)
2192 nigel 47 Version 3.2 12-May-00
2193     ---------------------
2195     This is purely a bug fixing release.
2197     1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2198     of ZA. This was just one example of several cases that could provoke this bug,
2199     which was introduced by change 9 of version 2.00. The code for breaking
2200     infinite loops after an iteration that matches an empty string was't working
2201     correctly.
2203     2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2204     when matched against abbab (for example). After matching an empty string, it
2205     wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2206     caused it to match further down the string than it should.
2208     3. The code contained an inclusion of sys/types.h. It isn't clear why this
2209     was there because it doesn't seem to be needed, and it causes trouble on some
2210     systems, as it is not a Standard C header. It has been removed.
2212     4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2213     were reported on the Macintosh. The changes were from
2215     while ((c = *(++ptr)) != 0 && c != '\n');
2216     to
2217     while ((c = *(++ptr)) != 0 && c != '\n') ;
2219     Totally extraordinary, but if that's what it takes...
2221     5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2222     available. Added HAVE_BCOPY and an autoconf test for it; if neither
2223     HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2224     assumes the way PCRE uses memmove() (always moving upwards).
2226     6. PCRE is being used in one environment where strchr() is not available. There
2227     was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2228     faster code anyway.
2231 nigel 45 Version 3.1 09-Feb-00
2232     ---------------------
2234     The only change in this release is the fixing of some bugs in Makefile.in for
2235     the "install" target:
2237     (1) It was failing to install pcreposix.h.
2239     (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2242 nigel 43 Version 3.0 01-Feb-00
2243     ---------------------
2244 nigel 41
2245     1. Add support for the /+ modifier to perltest (to output $` like it does in
2246     pcretest).
2248     2. Add support for the /g modifier to perltest.
2250     3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2251     matches null strings.
2253     4. Fix perltest so that it doesn't do unwanted things when fed an empty
2254     pattern. Perl treats empty patterns specially - it reuses the most recent
2255     pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2256     effect.
2258     5. The POSIX interface was broken in that it was just handing over the POSIX
2259     captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2260     required a bigger vector, with some working space on the end. This means that
2261     the POSIX wrapper now has to get and free some memory, and copy the results.
2263 nigel 43 6. Added some simple autoconf support, placing the test data and the
2264     documentation in separate directories, re-organizing some of the
2265     information files, and making it build pcre-config (a GNU standard). Also added
2266     libtool support for building PCRE as a shared library, which is now the
2267     default.
2268 nigel 41
2269 nigel 43 7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2270     09 are not valid octal constants. Single digits will be used for minor values
2271     less than 10.
2273     8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2274     existing programs that set these in the POSIX interface can use PCRE without
2275     modification.
2277     9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2278     return all that pcre_info() returns, plus additional data. The pcre_info()
2279     function is retained for compatibility, but is considered to be obsolete.
2281     10. Added experimental recursion feature (?R) to handle one common case that
2282     Perl 5.6 will be able to do with (?p{...}).
2284     11. Added support for POSIX character classes like [:alpha:], which Perl is
2285     adopting.
2288 nigel 39 Version 2.08 31-Aug-99
2289     ----------------------
2291     1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2292     trying to match at the startoffset position, but instead was moving forward to
2293     the next newline as if a previous match had failed.
2295     2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2296     and could get into a loop if a null string was matched other than at the start
2297     of the subject.
2299     3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2300     be distinguished at compile time, and for completeness also added PCRE_DATE.
2302     5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2303     in GnuWin32 environments.
2306 nigel 37 Version 2.07 29-Jul-99
2307     ----------------------
2309     1. The documentation is now supplied in plain text form and HTML as well as in
2310     the form of man page sources.
2312     2. C++ compilers don't like assigning (void *) values to other pointer types.
2313     In particular this affects malloc(). Although there is no problem in Standard
2314     C, I've put in casts to keep C++ compilers happy.
2316     3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2317     should be (const char *).
2319     4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2320     be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2321     However, I haven't made this a standard facility. The documentation doesn't
2322     mention it, and the Makefile doesn't support it.
2324     5. The Makefile now contains an "install" target, with editable destinations at
2325     the top of the file. The pcretest program is not installed.
2327     6. pgrep -V now gives the PCRE version number and date.
2329     7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2330     causing the entire string to be ignored, instead of just the last character.
2332     8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2333     non-matching string, it can take a very, very long time, even for strings of
2334     quite modest length, because of the nested recursion. PCRE now does better in
2335     some of these cases. It does this by remembering the last required literal
2336     character in the pattern, and pre-searching the subject to ensure it is present
2337     before running the real match. In other words, it applies a heuristic to detect
2338     some types of certain failure quickly, and in the above example, if presented
2339     with a string that has no trailing " it gives "no match" very quickly.
2341     9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2342     other alternatives are tried instead.
2345 nigel 35 Version 2.06 09-Jun-99
2346     ----------------------
2348     1. Change pcretest's output for amount of store used to show just the code
2349     space, because the remainder (the data block) varies in size between 32-bit and
2350     64-bit systems.
2352     2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2353     start matching at. This allows lookbehinds to work when searching for multiple
2354     occurrences in a string.
2356     3. Added additional options to pcretest for testing multiple occurrences:
2358     /+ outputs the rest of the string that follows a match
2359     /g loops for multiple occurrences, using the new startoffset argument
2360     /G loops for multiple occurrences by passing an incremented pointer
2362     4. PCRE wasn't doing the "first character" optimization for patterns starting
2363     with \b or \B, though it was doing it for other lookbehind assertions. That is,
2364     it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2365     the letter 'x'. On long subject strings, this gives a significant speed-up.
2368 nigel 33 Version 2.05 21-Apr-99
2369     ----------------------
2371     1. Changed the type of magic_number from int to long int so that it works
2372     properly on 16-bit systems.
2374     2. Fixed a bug which caused patterns starting with .* not to work correctly
2375     when the subject string contained newline characters. PCRE was assuming
2376     anchoring for such patterns in all cases, which is not correct because .* will
2377     not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2378     DOTALL is set at top level; otherwise it knows that patterns starting with .*
2379     must be retried after every newline in the subject.
2382 nigel 31 Version 2.04 18-Feb-99
2383     ----------------------
2385     1. For parenthesized subpatterns with repeats whose minimum was zero, the
2386     computation of the store needed to hold the pattern was incorrect (too large).
2387     If such patterns were nested a few deep, this could multiply and become a real
2388     problem.
2390     2. Added /M option to pcretest to show the memory requirement of a specific
2391     pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2393     3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2394     compiled in such a way that the backtracking after subsequent failure was
2395     pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2396     ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2399 nigel 29 Version 2.03 02-Feb-99
2400     ----------------------
2402     1. Fixed typo and small mistake in man page.
2404 nigel 31 2. Added 4th condition (GPL supersedes if conflict) and created separate
2405     LICENCE file containing the conditions.
2406 nigel 29
2407     3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2408     Perl, that is the internal \ allows the delimiter to be included in the
2409     pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2410     the final delimiter, add \ to the end of the pattern (to test the error).
2412     4. Added the convenience functions for extracting substrings after a successful
2413     match. Updated pcretest to make it able to test these functions.
2416 nigel 27 Version 2.02 14-Jan-99
2417     ----------------------
2419     1. Initialized the working variables associated with each extraction so that
2420     their saving and restoring doesn't refer to uninitialized store.
2422     2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2423     compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2424     fix the problem.
2426     3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2427     calls, and wasn't printing the correct value for compiling calls. Increased the
2428     default value of LOOPREPEAT, and the number of significant figures in the
2429     times.
2431     4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2433     5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2434     a building problem on Windows NT with a FAT file system.
2437 nigel 25 Version 2.01 21-Oct-98
2438     ----------------------
2440     1. Changed the API for pcre_compile() to allow for the provision of a pointer
2441     to character tables built by pcre_maketables() in the current locale. If NULL
2442     is passed, the default tables are used.
2445 nigel 23 Version 2.00 24-Sep-98
2446 nigel 21 ----------------------
2448 nigel 23 1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2449     it any more.
2451     2. Allow quantification of (?>) groups, and make it work correctly.
2453     3. The first character computation wasn't working for (?>) groups.
2455     4. Correct the implementation of \Z (it is permitted to match on the \n at the
2456     end of the subject) and add 5.005's \z, which really does match only at the
2457     very end of the subject.
2459     5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2461     6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2462     DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2463     localized options. All options to pcre_study() were also removed.
2465     7. Add other new features from 5.005:
2467     $(?<= positive lookbehind
2468     $(?<! negative lookbehind
2469     (?imsx-imsx) added the unsetting capability
2470     such a setting is global if at outer level; local otherwise
2471     (?imsx-imsx:) non-capturing groups with option setting
2472     (?(cond)re|re) conditional pattern matching
2474     A backreference to itself in a repeated group matches the previous
2475     captured string.
2477     8. General tidying up of studying (both automatic and via "study")
2478     consequential on the addition of new assertions.
2480     9. As in 5.005, unlimited repeated groups that could match an empty substring
2481     are no longer faulted at compile time. Instead, the loop is forcibly broken at
2482     runtime if any iteration does actually match an empty substring.
2484     10. Include the RunTest script in the distribution.
2486     11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2487     discrepancies, some of which were old and were also with respect to 5.004. They
2488     have now been fixed.
2491     Version 1.09 28-Apr-98
2492     ----------------------
2494 nigel 21 1. A negated single character class followed by a quantifier with a minimum
2495     value of one (e.g. [^x]{1,6} ) was not compiled correctly. This could lead to
2496     program crashes, or just wrong answers. This did not apply to negated classes
2497     containing more than one character, or to minima other than one.
2500 nigel 19 Version 1.08 27-Mar-98
2501     ----------------------
2503     1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
2505     2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
2506     latter must appear before anything that relies on it in the pattern.
2509 nigel 17 Version 1.07 16-Feb-98
2510     ----------------------
2512     1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
2513     repeat of a potentially empty string).
2516 nigel 15 Version 1.06 23-Jan-98
2517     ----------------------
2519     1. Added Markus Oberhumer's little patches for C++.
2521     2. Literal strings longer than 255 characters were broken.
2524 nigel 13 Version 1.05 23-Dec-97
2525     ----------------------
2527     1. Negated character classes containing more than one character were failing if
2528     PCRE_CASELESS was set at run time.
2531 nigel 11 Version 1.04 19-Dec-97
2532     ----------------------
2534     1. Corrected the man page, where some "const" qualifiers had been omitted.
2536     2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
2537     input syntax.
2539     3. Fixed memory leak which occurred when a regex with back references was
2540     matched with an offsets vector that wasn't big enough. The temporary memory
2541     that is used in this case wasn't being freed if the match failed.
2543     4. Tidied pcretest to ensure it frees memory that it gets.
2545     5. Temporary memory was being obtained in the case where the passed offsets
2546     vector was exactly big enough.
2548     6. Corrected definition of offsetof() from change 5 below.
2550     7. I had screwed up change 6 below and broken the rules for the use of
2551     setjmp(). Now fixed.
2554 nigel 9 Version 1.03 18-Dec-97
2555     ----------------------
2557     1. A erroneous regex with a missing opening parenthesis was correctly
2558     diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
2559     on some systems.
2561     2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
2562     it was reported that one broken compiler failed on the former because "code" is
2563     also an independent variable.
2565     3. The erroneous regex a[]b caused an array overrun reference.
2567     4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
2568     fail on data ending with that character. (It was going on too far, and checking
2569     the next character, typically a binary zero.) This was specific to the
2570     optimized code for single-character negative classes.
2572     5. Added a contributed patch from the TIN world which does the following:
2574     + Add an undef for memmove, in case the the system defines a macro for it.
2576     + Add a definition of offsetof(), in case there isn't one. (I don't know
2577     the reason behind this - offsetof() is part of the ANSI standard - but
2578     it does no harm).
2580     + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
2581     most of the places where whitespace preceded '#'. I have given up and
2582     allowed the remaining 2 cases to be at the margin.
2584     + Rename some variables in pcre to eliminate shadowing. This seems very
2585     pedantic, but does no harm, of course.
2587     6. Moved the call to setjmp() into its own function, to get rid of warnings
2588     from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.
2590     7. Constructs such as \d{8,} were compiling into the equivalent of
2591 nigel 11 \d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
2592 nigel 9 outcome, but in this particular case used more store than had been allocated,
2593     which caused the bug to be discovered because it threw up an internal error.
2595     8. The debugging code in both pcre and pcretest for outputting the compiled
2596     form of a regex was going wrong in the case of back references followed by
2597     curly-bracketed repeats.
2600 nigel 7 Version 1.02 12-Dec-97
2601     ----------------------
2603     1. Typos in pcre.3 and comments in the source fixed.
2605     2. Applied a contributed patch to get rid of places where it used to remove
2606     'const' from variables, and fixed some signed/unsigned and uninitialized
2607     variable warnings.
2609     3. Added the "runtest" target to Makefile.
2611     4. Set default compiler flag to -O2 rather than just -O.
2614 nigel 5 Version 1.01 19-Nov-97
2615     ----------------------
2617     1. PCRE was failing to diagnose unlimited repeat of empty string for patterns
2618     like /([ab]*)*/, that is, for classes with more than one character in them.
2620     2. Likewise, it wasn't diagnosing patterns with "once-only" subpatterns, such
2621     as /((?>a*))*/ (a PCRE_EXTRA facility).
2624     Version 1.00 18-Nov-97
2625     ----------------------
2627     1. Added compile-time macros to support systems such as SunOS4 which don't have
2628     memmove() or strerror() but have other things that can be used instead.
2630     2. Arranged that "make clean" removes the executables.
2633 nigel 3 Version 0.99 27-Oct-97
2634     ----------------------
2636     1. Fixed bug in code for optimizing classes with only one character. It was
2637     initializing a 32-byte map regardless, which could cause it to run off the end
2638     of the memory it had got.
2640     2. Added, conditional on PCRE_EXTRA, the proposed (?>REGEX) construction.
2643     Version 0.98 22-Oct-97
2644     ----------------------
2646     1. Fixed bug in code for handling temporary memory usage when there are more
2647     back references than supplied space in the ovector. This could cause segfaults.
2650     Version 0.97 21-Oct-97
2651     ----------------------
2653     1. Added the \X "cut" facility, conditional on PCRE_EXTRA.
2655     2. Optimized negated single characters not to use a bit map.
2657     3. Brought error texts together as macro definitions; clarified some of them;
2658     fixed one that was wrong - it said "range out of order" when it meant "invalid
2659     escape sequence".
2661     4. Changed some char * arguments to const char *.
2663     5. Added PCRE_NOTBOL and PCRE_NOTEOL (from POSIX).
2665     6. Added the POSIX-style API wrapper in pcreposix.a and testing facilities in
2666     pcretest.
2669     Version 0.96 16-Oct-97
2670     ----------------------
2672     1. Added a simple "pgrep" utility to the distribution.
2674     2. Fixed an incompatibility with Perl: "{" is now treated as a normal character
2675     unless it appears in one of the precise forms "{ddd}", "{ddd,}", or "{ddd,ddd}"
2676     where "ddd" means "one or more decimal digits".
2678     3. Fixed serious bug. If a pattern had a back reference, but the call to
2679     pcre_exec() didn't supply a large enough ovector to record the related
2680     identifying subpattern, the match always failed. PCRE now remembers the number
2681     of the largest back reference, and gets some temporary memory in which to save
2682     the offsets during matching if necessary, in order to ensure that
2683     backreferences always work.
2685     4. Increased the compatibility with Perl in a number of ways:
2687     (a) . no longer matches \n by default; an option PCRE_DOTALL is provided
2688     to request this handling. The option can be set at compile or exec time.
2690     (b) $ matches before a terminating newline by default; an option
2691     PCRE_DOLLAR_ENDONLY is provided to override this (but not in multiline
2692     mode). The option can be set at compile or exec time.
2694     (c) The handling of \ followed by a digit other than 0 is now supposed to be
2695     the same as Perl's. If the decimal number it represents is less than 10
2696     or there aren't that many previous left capturing parentheses, an octal
2697     escape is read. Inside a character class, it's always an octal escape,
2698     even if it is a single digit.
2700     (d) An escaped but undefined alphabetic character is taken as a literal,
2701     unless PCRE_EXTRA is set. Currently this just reserves the remaining
2702     escapes.
2704     (e) {0} is now permitted. (The previous item is removed from the compiled
2705     pattern).
2707     5. Changed all the names of code files so that the basic parts are no longer
2708     than 10 characters, and abolished the teeny "globals.c" file.
2710     6. Changed the handling of character classes; they are now done with a 32-byte
2711     bit map always.
2713     7. Added the -d and /D options to pcretest to make it possible to look at the
2714     internals of compilation without having to recompile pcre.
2717     Version 0.95 23-Sep-97
2718     ----------------------
2720     1. Fixed bug in pre-pass concerning escaped "normal" characters such as \x5c or
2721     \x20 at the start of a run of normal characters. These were being treated as
2722     real characters, instead of the source characters being re-checked.
2725     Version 0.94 18-Sep-97
2726     ----------------------
2728     1. The functions are now thread-safe, with the caveat that the global variables
2729     containing pointers to malloc() and free() or alternative functions are the
2730     same for all threads.
2732     2. Get pcre_study() to generate a bitmap of initial characters for non-
2733     anchored patterns when this is possible, and use it if passed to pcre_exec().
2736     Version 0.93 15-Sep-97
2737     ----------------------
2739     1. /(b)|(:+)/ was computing an incorrect first character.
2741     2. Add pcre_study() to the API and the passing of pcre_extra to pcre_exec(),
2742     but not actually doing anything yet.
2744     3. Treat "-" characters in classes that cannot be part of ranges as literals,
2745     as Perl does (e.g. [-az] or [az-]).
2747     4. Set the anchored flag if a branch starts with .* or .*? because that tests
2748     all possible positions.
2750     5. Split up into different modules to avoid including unneeded functions in a
2751     compiled binary. However, compile and exec are still in one module. The "study"
2752     function is split off.
2754     6. The character tables are now in a separate module whose source is generated
2755     by an auxiliary program - but can then be edited by hand if required. There are
2756     now no calls to isalnum(), isspace(), isdigit(), isxdigit(), tolower() or
2757     toupper() in the code.
2759     7. Turn the malloc/free funtions variables into pcre_malloc and pcre_free and
2760     make them global. Abolish the function for setting them, as the caller can now
2761     set them directly.
2764     Version 0.92 11-Sep-97
2765     ----------------------
2767     1. A repeat with a fixed maximum and a minimum of 1 for an ordinary character
2768     (e.g. /a{1,3}/) was broken (I mis-optimized it).
2770     2. Caseless matching was not working in character classes if the characters in
2771     the pattern were in upper case.
2773     3. Make ranges like [W-c] work in the same way as Perl for caseless matching.
2775     4. Make PCRE_ANCHORED public and accept as a compile option.
2777     5. Add an options word to pcre_exec() and accept PCRE_ANCHORED and
2778     PCRE_CASELESS at run time. Add escapes \A and \I to pcretest to cause it to
2779     pass them.
2781     6. Give an error if bad option bits passed at compile or run time.
2783     7. Add PCRE_MULTILINE at compile and exec time, and (?m) as well. Add \M to
2784     pcretest to cause it to pass that flag.
2786     8. Add pcre_info(), to get the number of identifying subpatterns, the stored
2787     options, and the first character, if set.
2789     9. Recognize C+ or C{n,m} where n >= 1 as providing a fixed starting character.
2792     Version 0.91 10-Sep-97
2793     ----------------------
2795     1. PCRE was failing to diagnose unlimited repeats of subpatterns that could
2796     match the empty string as in /(a*)*/. It was looping and ultimately crashing.
2798     2. PCRE was looping on encountering an indefinitely repeated back reference to
2799     a subpattern that had matched an empty string, e.g. /(a|)\1*/. It now does what
2800     Perl does - treats the match as successful.
2802     ****


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