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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 8.00 ??-???-??  Version 8.31
5    -----------------------------
7    1.  Fixing a wrong JIT test case and some compiler warnings.
9    2.  Removed a bashism from the RunTest script.
11    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
12        to unsigned type, result still unsigned" that was given by an MS compiler
13        on encountering the code "-sizeof(xxx)".
15    4.  Partial matching support is added to the JIT compiler.
17    5.  Fixed several bugs concerned with partial matching of items that consist
18        of more than one character:
20        (a) /^(..)\1/ did not partially match "aba" because checking references was
21            done on an "all or nothing" basis. This also applied to repeated
22            references.
24        (b) \R did not give a hard partial match if \r was found at the end of the
25            subject.
27        (c) \X did not give a hard partial match after matching one or more
28            characters at the end of the subject.
30        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
31            a partial match for the string "\r".
33        (e) When newline was set to CRLF, the metacharacter "." did not recognize
34            a partial match for a CR character at the end of the subject string.
36    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
37        running pcretest, the text "(JIT)" added to the output whenever JIT is
38        actually used to run the match.
40    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
41        or /S+[+] with a digit between 1 and 7.
43    8.  OP_NOT now supports any UTF character not just single-byte ones.
45    9.  (*MARK) control verb is now supported by the JIT compiler.
47    10. The command "./RunTest list" lists the available tests without actually
48        running any of them. (Because I keep forgetting what they all are.)
52    12. Applied a (slightly modified) user-supplied patch that improves performance
53        when the heap is used for recursion (compiled with --disable-stack-for-
54        recursion). Instead of malloc and free for each heap frame each time a
55        logical recursion happens, frames are retained on a chain and re-used where
56        possible. This sometimes gives as much as 30% improvement.
58    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
59        call.
61    14. As documented, (*COMMIT) is now confined to within a positive assertion.
63    15. It is now possible to link pcretest with libedit as an alternative to
64        libreadline.
66    16. (*COMMIT) control verb is now supported by the JIT compiler.
68    17. The Unicode data tables have been updated to Unicode 6.1.0.
70    18. Added --file-list option to pcregrep.
72    19. Added binary file support to pcregrep, including the -a, --binary-files,
73        -I, and --text options.
75    20. The madvise function is renamed for posix_madvise for QNX compatibility
76        reasons. Fixed by Giuseppe D'Angelo.
78    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
80    22. Changed the option for creating symbolic links for 16-bit man pages from
81        -s to -sf so that re-installing does not cause issues.
83    23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.
85    24. Fixed a very old bug in pcretest that caused errors with restarted DFA
86        matches in certain environments (the workspace was not being correctly
87        retained). Also added to pcre_dfa_exec() a simple plausibility check on
88        some of the workspace data at the beginning of a restart.
90    25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
91        was not doing so when it should - probably a typo introduced by SVN 528
92        (change 8.10/14).
95    Version 8.30 04-February-2012
96    -----------------------------
98    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
99        name is defined in ctype.h.
101    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
102        only in quite long subpatterns.
104    3.  Removed the function pcre_info(), which has been obsolete and deprecated
105        since it was replaced by pcre_fullinfo() in February 2000.
107    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
108        match a (*MARK), and the match failed at the start of the subject, a
109        reference to memory before the start of the subject could occur. This bug
110        was introduced by fix 17 of release 8.21.
112    5.  A reference to an unset group with zero minimum repetition was giving
113        totally wrong answers (in non-JavaScript-compatibility mode). For example,
114        /(another)?(\1?)test/ matched against "hello world test". This bug was
115        introduced in release 8.13.
117    6.  Add support for 16-bit character strings (a large amount of work involving
118        many changes and refactorings).
120    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
121        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
122        from a file.
124    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
125        rounding is not applied in this particular case).
127    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
128        if they appear, or are escaped, in patterns.
130    10. Get rid of a number of -Wunused-but-set-variable warnings.
132    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
133        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
134        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
135        also returns the mark "x". This bug applied to capturing parentheses,
136        non-capturing parentheses, and atomic parentheses. It also applied to some
137        assertions.
139    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
140        information out of configure.ac instead of relying on pcre.h.generic, which
141        is not stored in the repository.
143    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
144        -lreadline.
146    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
148    15. Applied Graycode's patch to put the top-level frame on the stack rather
149        than the heap when not using the stack for recursion. This gives a
150        performance improvement in many cases when recursion is not deep.
152    16. Experimental code added to "pcretest -C" to output the stack frame size.
155    Version 8.21 12-Dec-2011
156    ------------------------
158    1.  Updating the JIT compiler.
160    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
161        are added as well.
163    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
164        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
165        calling _pcre_jit_exec. Some extra comments are added.
167    4.  (*MARK) settings inside atomic groups that do not contain any capturing
168        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
169        was introduced by change 18 for 8.20.
171    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
172        ECMA-262 standard.
174    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
175        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
176        This bug was probably introduced by change 9 of 8.13.
178    7.  While fixing 6 above, I noticed that a number of other items were being
179        incorrectly rejected as "not fixed length". This arose partly because newer
180        opcodes had not been added to the fixed-length checking code. I have (a)
181        corrected the bug and added tests for these items, and (b) arranged for an
182        error to occur if an unknown opcode is encountered while checking for fixed
183        length instead of just assuming "not fixed length". The items that were
184        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
185        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
186        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
188    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
189        being incorrectly compiled and would have given unpredicatble results.
191    9.  A possessively repeated subpattern with minimum repeat count greater than
192        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
193        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
194        the first (A) could occur when it should not.
196    10. Add a cast and remove a redundant test from the code.
198    11. JIT should use pcre_malloc/pcre_free for allocation.
200    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
201        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
202        is anything other than /usr, -L is still shown).
204    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
206    14. Perl does not support \N without a following name in a [] class; PCRE now
207        also gives an error.
209    15. If a forward reference was repeated with an upper limit of around 2000,
210        it caused the error "internal error: overran compiling workspace". The
211        maximum number of forward references (including repeats) was limited by the
212        internal workspace, and dependent on the LINK_SIZE. The code has been
213        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
214        the default depends on LINK_SIZE. There is a new upper limit (for safety)
215        of around 200,000 forward references. While doing this, I also speeded up
216        the filling in of repeated forward references.
218    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
219        incorrectly expecting the subject to contain another "a" after the start.
221    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
222        in the match, the SKIP should be ignored. This was not happening; instead
223        the SKIP was being treated as NOMATCH. For patterns such as
224        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
225        tested.
227    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
228        now much more compatible with Perl, in particular in cases where the result
229        is a non-match for a non-anchored pattern. For example, if
230        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
231        "m", where previously it did not return a name. A side effect of this
232        change is that for partial matches, the last encountered mark name is
233        returned, as for non matches. A number of tests that were previously not
234        Perl-compatible have been moved into the Perl-compatible test files. The
235        refactoring has had the pleasing side effect of removing one argument from
236        the match() function, thus reducing its stack requirements.
238    19. If the /S+ option was used in pcretest to study a pattern using JIT,
239        subsequent uses of /S (without +) incorrectly behaved like /S+.
241    21. Retrieve executable code size support for the JIT compiler and fixing
242        some warnings.
244    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
245        not work when the shorter character appeared right at the end of the
246        subject string.
248    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
249        systems.
251    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
252        output it when the /M option is used in pcretest.
254    25. The CheckMan script was not being included in the distribution. Also, added
255        an explicit "perl" to run Perl scripts from the PrepareRelease script
256        because this is reportedly needed in Windows.
258    26. If study data was being save in a file and studying had not found a set of
259        "starts with" bytes for the pattern, the data written to the file (though
260        never used) was taken from uninitialized memory and so caused valgrind to
261        complain.
263    27. Updated RunTest.bat as provided by Sheri Pierce.
265    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
267    29. Computation of memory usage for the table of capturing group names was
268        giving an unnecessarily large value.
271    Version 8.20 21-Oct-2011
272    ------------------------
274    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
275        a POSIX class. After further experiments with Perl, which convinced me that
276        Perl has bugs and confusions, a closing square bracket is no longer allowed
277        in a POSIX name. This bug also affected patterns with classes that started
278        with full stops.
280    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
281        captured substring, but while checking the failing first alternative,
282        substring 1 is temporarily captured. If the output vector supplied to
283        pcre_exec() was not big enough for this capture, the yield of the function
284        was still zero ("insufficient space for captured substrings"). This cannot
285        be totally fixed without adding another stack variable, which seems a lot
286        of expense for a edge case. However, I have improved the situation in cases
287        such as /(a)(b)x|abc/ matched against "abc", where the return code
288        indicates that fewer than the maximum number of slots in the ovector have
289        been set.
291    3.  Related to (2) above: when there are more back references in a pattern than
292        slots in the output vector, pcre_exec() uses temporary memory during
293        matching, and copies in the captures as far as possible afterwards. It was
294        using the entire output vector, but this conflicts with the specification
295        that only 2/3 is used for passing back captured substrings. Now it uses
296        only the first 2/3, for compatibility. This is, of course, another edge
297        case.
299    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
300        main code base, and can be used by building with --enable-jit. When this is
301        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
302        runtime --no-jit option is given.
304    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
305        ovector, the return from the function was zero, implying that there were
306        other matches that did not fit. The correct "exactly full" value is now
307        returned.
309    6.  If a subpattern that was called recursively or as a subroutine contained
310        (*PRUNE) or any other control that caused it to give a non-standard return,
311        invalid errors such as "Error -26 (nested recursion at the same subject
312        position)" or even infinite loops could occur.
314    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
315        computing the minimum length on reaching *ACCEPT, and so ended up with the
316        wrong value of 1 rather than 0. Further investigation indicates that
317        computing a minimum subject length in the presence of *ACCEPT is difficult
318        (think back references, subroutine calls), and so I have changed the code
319        so that no minimum is registered for a pattern that contains *ACCEPT.
321    8.  If (*THEN) was present in the first (true) branch of a conditional group,
322        it was not handled as intended. [But see 16 below.]
324    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
325        Sheri Pierce.
327    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
328        the first byte in a match must be "a".
330    11. Change 17 for 8.13 increased the recursion depth for patterns like
331        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
332        pattern contains any instances of (*THEN). If it does not, the old
333        optimizations are restored. It would be nice to do this on a per-group
334        basis, but at the moment that is not feasible.
336    12. In some environments, the output of pcretest -C is CRLF terminated. This
337        broke RunTest's code that checks for the link size. A single white space
338        character after the value is now allowed for.
340    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
341        For "fr", it uses the Windows-specific input and output files.
343    14. If (*THEN) appeared in a group that was called recursively or as a
344        subroutine, it did not work as intended. [But see next item.]
346    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
347        pattern fragments (but not containing any | characters). If A and B are
348        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
349        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
350        D. In other words, Perl considers parentheses that do not contain any |
351        characters to be part of a surrounding alternative, whereas PCRE was
352        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
353        differently. PCRE now behaves in the same way as Perl, except in the case
354        of subroutine/recursion calls such as (?1) which have in any case always
355        been different (but PCRE had them first :-).
357    16. Related to 15 above: Perl does not treat the | in a conditional group as
358        creating alternatives. Such a group is treated in the same way as an
359        ordinary group without any | characters when processing (*THEN). PCRE has
360        been changed to match Perl's behaviour.
362    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
363        RunGrepTest script failed.
365    18. Change 22 for version 13 caused atomic groups to use more stack. This is
366        inevitable for groups that contain captures, but it can lead to a lot of
367        stack use in large patterns. The old behaviour has been restored for atomic
368        groups that do not contain any capturing parentheses.
370    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
371        suppress the check for a minimum subject length at run time. (If it was
372        given to pcre_exec() or pcre_dfa_exec() it did work.)
374    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
375        fail to work when decoding hex characters in data strings in EBCDIC
376        environments.
378    21. It appears that in at least one Mac OS environment, the isxdigit() function
379        is implemented as a macro that evaluates to its argument more than once,
380        contravening the C 90 Standard (I haven't checked a later standard). There
381        was an instance in pcretest which caused it to go wrong when processing
382        \x{...} escapes in subject strings. The has been rewritten to avoid using
383        things like p++ in the argument of isxdigit().
386    Version 8.13 16-Aug-2011
387    ------------------------
389    1.  The Unicode data tables have been updated to Unicode 6.0.0.
391    2.  Two minor typos in pcre_internal.h have been fixed.
393    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
394        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
395        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
397    4.  There were a number of related bugs in the code for matching backrefences
398        caselessly in UTF-8 mode when codes for the characters concerned were
399        different numbers of bytes. For example, U+023A and U+2C65 are an upper
400        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
401        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
402        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
403        2-byte code at the end of the subject (it thought there wasn't enough data
404        left).
406    5.  Comprehensive information about what went wrong is now returned by
407        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
408        as the output vector has at least 2 elements. The offset of the start of
409        the failing character and a reason code are placed in the vector.
411    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
412        now returned is for the first byte of the failing character, instead of the
413        last byte inspected. This is an incompatible change, but I hope it is small
414        enough not to be a problem. It makes the returned offset consistent with
415        pcre_exec() and pcre_dfa_exec().
417    7.  pcretest now gives a text phrase as well as the error number when
418        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
419        failure, the offset and reason code are output.
421    8.  When \R was used with a maximizing quantifier it failed to skip backwards
422        over a \r\n pair if the subsequent match failed. Instead, it just skipped
423        back over a single character (\n). This seems wrong (because it treated the
424        two characters as a single entity when going forwards), conflicts with the
425        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
426        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
427        has been changed.
429    9.  Some internal refactoring has changed the processing so that the handling
430        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
431        time (the PCRE_DOTALL option was changed this way some time ago: version
432        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
433        which was always a bit of a fudge. It also means that there is one less
434        argument for the match() function, which reduces its stack requirements
435        slightly. This change also fixes an incompatibility with Perl: the pattern
436        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
438    10. More internal refactoring has drastically reduced the number of recursive
439        calls to match() for possessively repeated groups such as (abc)++ when
440        using pcre_exec().
442    11. While implementing 10, a number of bugs in the handling of groups were
443        discovered and fixed:
445        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
446        (a|)*(?1) gave a compile-time internal error.
447        ((a|)+)+  did not notice that the outer group could match an empty string.
448        (^a|^)+   was not marked as anchored.
449        (.*a|.*)+ was not marked as matching at start or after a newline.
451    12. Yet more internal refactoring has removed another argument from the match()
452        function. Special calls to this function are now indicated by setting a
453        value in a variable in the "match data" data block.
455    13. Be more explicit in pcre_study() instead of relying on "default" for
456        opcodes that mean there is no starting character; this means that when new
457        ones are added and accidentally left out of pcre_study(), testing should
458        pick them up.
460    14. The -s option of pcretest has been documented for ages as being an old
461        synonym of -m (show memory usage). I have changed it to mean "force study
462        for every regex", that is, assume /S for every regex. This is similar to -i
463        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
464        using it. It makes it easier to run collections of tests with and without
465        study enabled, and thereby test pcre_study() more easily. All the standard
466        tests are now run with and without -s (but some patterns can be marked as
467        "never study" - see 20 below).
469    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
470        restoration of the capturing data to the outer values was not happening
471        correctly.
473    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
474        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
475        pattern had matched an empty string, and so incorrectly returned a no
476        match.
478    17. There was optimizing code for the last branch of non-capturing parentheses,
479        and also for the obeyed branch of a conditional subexpression, which used
480        tail recursion to cut down on stack usage. Unfortunately, now that there is
481        the possibility of (*THEN) occurring in these branches, tail recursion is
482        no longer possible because the return has to be checked for (*THEN). These
483        two optimizations have therefore been removed. [But see 8.20/11 above.]
485    18. If a pattern containing \R was studied, it was assumed that \R always
486        matched two bytes, thus causing the minimum subject length to be
487        incorrectly computed because \R can also match just one byte.
489    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
490        was incorrectly computed.
492    20. If /S is present twice on a test pattern in pcretest input, it now
493        *disables* studying, thereby overriding the use of -s on the command line
494        (see 14 above). This is necessary for one or two tests to keep the output
495        identical in both cases.
497    21. When (*ACCEPT) was used in an assertion that matched an empty string and
498        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
500    22. When an atomic group that contained a capturing parenthesis was
501        successfully matched, but the branch in which it appeared failed, the
502        capturing was not being forgotten if a higher numbered group was later
503        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
504        group 1 to "a", when in fact it should be unset. This applied to multi-
505        branched capturing and non-capturing groups, repeated or not, and also to
506        positive assertions (capturing in negative assertions does not happen
507        in PCRE) and also to nested atomic groups.
509    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
510        subject after a captured substring, to make it easier to tell which of a
511        number of identical substrings has been captured.
513    24. The way atomic groups are processed by pcre_exec() has been changed so that
514        if they are repeated, backtracking one repetition now resets captured
515        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
516        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
517        "aaa". Previously, it would have been "a". As part of this code
518        refactoring, the way recursive calls are handled has also been changed.
520    25. If an assertion condition captured any substrings, they were not passed
521        back unless some other capturing happened later. For example, if
522        (?(?=(a))a) was matched against "a", no capturing was returned.
524    26. When studying a pattern that contained subroutine calls or assertions,
525        the code for finding the minimum length of a possible match was handling
526        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
527        group 1 called group 2 while simultaneously a separate group 2 called group
528        1). A stack overflow occurred in this case. I have fixed this by limiting
529        the recursion depth to 10.
531    27. Updated RunTest.bat in the distribution to the version supplied by Tom
532        Fortmann. This supports explicit test numbers on the command line, and has
533        argument validation and error reporting.
535    28. An instance of \X with an unlimited repeat could fail if at any point the
536        first character it looked at was a mark character.
538    29. Some minor code refactoring concerning Unicode properties and scripts
539        should reduce the stack requirement of match() slightly.
541    30. Added the '=' option to pcretest to check the setting of unused capturing
542        slots at the end of the pattern, which are documented as being -1, but are
543        not included in the return count.
545    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
546        compiled something random. Now it gives a compile-time error (as does
547        Perl).
549    32. A *MARK encountered during the processing of a positive assertion is now
550        recorded and passed back (compatible with Perl).
552    33. If --only-matching or --colour was set on a pcregrep call whose pattern
553        had alternative anchored branches, the search for a second match in a line
554        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
555        matched the line "0102" twice. The same bug affected patterns that started
556        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
557        twice.
559    34. Previously, PCRE did not allow quantification of assertions. However, Perl
560        does, and because of capturing effects, quantifying parenthesized
561        assertions may at times be useful. Quantifiers are now allowed for
562        parenthesized assertions.
564    35. A minor code tidy in pcre_compile() when checking options for \R usage.
566    36. \g was being checked for fancy things in a character class, when it should
567        just be a literal "g".
569    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
570        appearance of a nested POSIX class supersedes an apparent external class.
571        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
572        unescaped square brackets may also appear as part of class names. For
573        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
574        more like Perl. (But see 8.20/1 above.)
576    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
577        was because it thought it was \N{name}, which is not supported).
579    39. Add minix to OS list not supporting the -S option in pcretest.
581    40. PCRE tries to detect cases of infinite recursion at compile time, but it
582        cannot analyze patterns in sufficient detail to catch mutual recursions
583        such as ((?1))((?2)). There is now a runtime test that gives an error if a
584        subgroup is called recursively as a subpattern for a second time at the
585        same position in the subject string. In previous releases this might have
586        been caught by the recursion limit, or it might have run out of stack.
588    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
589        happen only once. PCRE was, however incorrectly giving a compile time error
590        "recursive call could loop indefinitely" because it cannot analyze the
591        pattern in sufficient detail. The compile time test no longer happens when
592        PCRE is compiling a conditional subpattern, but actual runaway loops are
593        now caught at runtime (see 40 above).
595    42. It seems that Perl allows any characters other than a closing parenthesis
596        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
597        has been changed to be the same.
599    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
600        as not to get warnings when autogen.sh is called. Also changed
601        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
603    44. To help people who use pcregrep to scan files containing exceedingly long
604        lines, the following changes have been made:
606        (a) The default value of the buffer size parameter has been increased from
607            8K to 20K. (The actual buffer used is three times this size.)
609        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
610            PCRE is built.
612        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
613            to be set at run time.
615        (d) Numerical values in pcregrep options can be followed by K or M, for
616            example --buffer-size=50K.
618        (e) If a line being scanned overflows pcregrep's buffer, an error is now
619            given and the return code is set to 2.
621    45. Add a pointer to the latest mark to the callout data block.
623    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
624        partial match of an empty string instead of no match. This was specific to
625        the use of ".".
627    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
628        complete match instead of a partial match. This bug was dependent on both
629        the PCRE_UTF8 and PCRE_DOTALL options being set.
631    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
632        starting byte set, because \b was not being ignored.
635    Version 8.12 15-Jan-2011
636    ------------------------
638    1.  Fixed some typos in the markup of the man pages, and wrote a script that
639        checks for such things as part of the documentation building process.
641    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
642        --match-limit and --recursion-limit options (added for 8.11). In
643        particular, this made one of the standard tests fail. (The integer value
644        went into the wrong half of a long int.)
646    3.  If the --colour option was given to pcregrep with -v (invert match), it
647        did strange things, either producing crazy output, or crashing. It should,
648        of course, ignore a request for colour when reporting lines that do not
649        match.
651    4.  Another pcregrep bug caused similar problems if --colour was specified with
652        -M (multiline) and the pattern match finished with a line ending.
654    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
655        matched in multiline mode, the following line was shown as part of the
656        match. This seems wrong, so I have changed it.
658    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
659        the check for further matches in the same line (so they could be coloured)
660        to overrun the end of the current line. If another match was found, it was
661        incorrectly shown (and then shown again when found in the next line).
663    7.  If pcregrep was compiled under Windows, there was a reference to the
664        function pcregrep_exit() before it was defined. I am assuming this was
665        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
666        reported by a user. I've moved the definition above the reference.
669    Version 8.11 10-Dec-2010
670    ------------------------
672    1.  (*THEN) was not working properly if there were untried alternatives prior
673        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
674        backtracked to try for "b" instead of moving to the next alternative branch
675        at the same level (in this case, to look for "c"). The Perl documentation
676        is clear that when (*THEN) is backtracked onto, it goes to the "next
677        alternative in the innermost enclosing group".
679    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
680        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
681        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
682        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
683        (*THEN).
685    3.  If \s appeared in a character class, it removed the VT character from
686        the class, even if it had been included by some previous item, for example
687        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
688        of \s, but is part of the POSIX "space" class.)
690    4.  A partial match never returns an empty string (because you can always
691        match an empty string at the end of the subject); however the checking for
692        an empty string was starting at the "start of match" point. This has been
693        changed to the "earliest inspected character" point, because the returned
694        data for a partial match starts at this character. This means that, for
695        example, /(?<=abc)def/ gives a partial match for the subject "abc"
696        (previously it gave "no match").
698    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
699        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
700        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
701        has an implication that the given string is incomplete (because a partial
702        match is preferred over a full match). For this reason, these items now
703        give a partial match in this situation. [Aside: previously, the one case
704        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
705        match rather than a full match, which was wrong by the old rules, but is
706        now correct.]
708    6.  There was a bug in the handling of #-introduced comments, recognized when
709        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
710        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
711        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
712        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
713        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
714        places in pcre_compile().
716    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
717        comments when looking ahead for named forward references to subpatterns,
718        the only newline sequence it recognized was NL. It now handles newlines
719        according to the set newline convention.
721    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
722        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
723        cater for a lack of strerror(). These oversights have been fixed.
725    9.  Added --match-limit and --recursion-limit to pcregrep.
727    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
729    11. When the -o option was used, pcregrep was setting a return code of 1, even
730        when matches were found, and --line-buffered was not being honoured.
732    12. Added an optional parentheses number to the -o and --only-matching options
733        of pcregrep.
735    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
736        can match an empty string. The code to do it in pcretest and pcredemo
737        needed fixing:
739        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
740            only one byte after an empty string match just before CRLF (this case
741            just got forgotten; "any" and "anycrlf" were OK).
743        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
744            mode when an empty string match preceded an ASCII character followed by
745            a non-ASCII character. (The code for advancing by one character rather
746            than one byte was nonsense.)
748        (c) The pcredemo.c sample program did not have any code at all to handle
749            the cases when CRLF is a valid newline sequence.
751    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
752        as a starting offset was within the subject string. There is now a new
753        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
754        negative or greater than the length of the string. In order to test this,
755        pcretest is extended to allow the setting of negative starting offsets.
757    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
758        starting offset points to the beginning of a UTF-8 character was
759        unnecessarily clumsy. I tidied it up.
761    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
762        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
764    17. Nobody had reported that the --include_dir option, which was added in
765        release 7.7 should have been called --include-dir (hyphen, not underscore)
766        for compatibility with GNU grep. I have changed it to --include-dir, but
767        left --include_dir as an undocumented synonym, and the same for
768        --exclude-dir, though that is not available in GNU grep, at least as of
769        release 2.5.4.
771    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
772        characters from a string of bytes) have been redefined so as not to use
773        loops, in order to improve performance in some environments. At the same
774        time, I abstracted some of the common code into auxiliary macros to save
775        repetition (this should not affect the compiled code).
777    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
778        compile-time error is now given if \c is not followed by an ASCII
779        character, that is, a byte less than 128. (In EBCDIC mode, the code is
780        different, and any byte value is allowed.)
782    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
783        START_OPTIMIZE option, which is now allowed at compile time - but just
784        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
785        to pcregrep and other applications that have no direct access to PCRE
786        options. The new /Y option in pcretest sets this option when calling
787        pcre_compile().
789    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
790        back references. Groups containing recursive back references were forced to
791        be atomic by that change, but in the case of named groups, the amount of
792        memory required was incorrectly computed, leading to "Failed: internal
793        error: code overflow". This has been fixed.
795    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
796        pcretest.c, to avoid build problems in some Borland environments.
799    Version 8.10 25-Jun-2010
800    ------------------------
802    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
803        THEN.
805    2.  (*ACCEPT) was not working when inside an atomic group.
807    3.  Inside a character class, \B is treated as a literal by default, but
808        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
809        causes the error). The code is unchanged, but I tidied the documentation.
811    4.  Inside a character class, PCRE always treated \R and \X as literals,
812        whereas Perl faults them if its -w option is set. I have changed PCRE so
813        that it faults them when PCRE_EXTRA is set.
815    5.  Added support for \N, which always matches any character other than
816        newline. (It is the same as "." when PCRE_DOTALL is not set.)
818    6.  When compiling pcregrep with newer versions of gcc which may have
819        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
820        declared with attribute warn_unused_result" were given. Just casting the
821        result to (void) does not stop the warnings; a more elaborate fudge is
822        needed. I've used a macro to implement this.
824    7.  Minor change to pcretest.c to avoid a compiler warning.
826    8.  Added four artifical Unicode properties to help with an option to make
827        \s etc use properties (see next item). The new properties are: Xan
828        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
830    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
831        use Unicode properties. (*UCP) at the start of a pattern can be used to set
832        this option. Modified pcretest to add /W to test this facility. Added
833        REG_UCP to make it available via the POSIX interface.
835    10. Added --line-buffered to pcregrep.
837    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
838        studied, and the match started with a letter with a code point greater than
839        127 whose first byte was different to the first byte of the other case of
840        the letter, the other case of this starting letter was not recognized
841        (#976).
843    12. If a pattern that was studied started with a repeated Unicode property
844        test, for example, \p{Nd}+, there was the theoretical possibility of
845        setting up an incorrect bitmap of starting bytes, but fortunately it could
846        not have actually happened in practice until change 8 above was made (it
847        added property types that matched character-matching opcodes).
849    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
850        possible starting bytes for non-anchored patterns.
852    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
853        \R, and also a number of cases that involve Unicode properties, both
854        explicit and implicit when PCRE_UCP is set.
856    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
857        input, it could crash or give wrong results if characters with values
858        greater than 0xc0 were present in the subject string. (Detail: it assumed
859        UTF-8 input when processing these items.)
861    16. Added a lot of (int) casts to avoid compiler warnings in systems where
862        size_t is 64-bit (#991).
864    17. Added a check for running out of memory when PCRE is compiled with
865        --disable-stack-for-recursion (#990).
867    18. If the last data line in a file for pcretest does not have a newline on
868        the end, a newline was missing in the output.
870    19. The default pcre_chartables.c file recognizes only ASCII characters (values
871        less than 128) in its various bitmaps. However, there is a facility for
872        generating tables according to the current locale when PCRE is compiled. It
873        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
874        characters, are recognized by isspace() and therefore were getting set in
875        these tables, and indeed these tables seem to approximate to ISO 8859. This
876        caused a problem in UTF-8 mode when pcre_study() was used to create a list
877        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
878        which of course cannot start UTF-8 characters. I have changed the code so
879        that only real ASCII characters (less than 128) and the correct starting
880        bytes for UTF-8 encodings are set for characters greater than 127 when in
881        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
882        altogether.)
884    20. Added the /T option to pcretest so as to be able to run tests with non-
885        standard character tables, thus making it possible to include the tests
886        used for 19 above in the standard set of tests.
888    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
889        reference to a subpattern the other side of a comment that contains an
890        opening parenthesis caused either an internal compiling error, or a
891        reference to the wrong subpattern.
894    Version 8.02 19-Mar-2010
895    ------------------------
897    1.  The Unicode data tables have been updated to Unicode 5.2.0.
899    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
900        configured.
902    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
903        original author of that file, following a query about its status.
905    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
906        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
908    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
909        quantifier applied to a forward-referencing subroutine call, could compile
910        incorrect code or give the error "internal error: previously-checked
911        referenced subpattern not found".
913    6.  Both MS Visual Studio and Symbian OS have problems with initializing
914        variables to point to external functions. For these systems, therefore,
915        pcre_malloc etc. are now initialized to local functions that call the
916        relevant global functions.
918    7.  There were two entries missing in the vectors called coptable and poptable
919        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
920        I've fixed the data, and added a kludgy way of testing at compile time that
921        the lengths are correct (equal to the number of opcodes).
923    8.  Following on from 7, I added a similar kludge to check the length of the
924        eint vector in pcreposix.c.
926    9.  Error texts for pcre_compile() are held as one long string to avoid too
927        much relocation at load time. To find a text, the string is searched,
928        counting zeros. There was no check for running off the end of the string,
929        which could happen if a new error number was added without updating the
930        string.
932    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
934    11. \K was not working if it appeared in an atomic group or in a group that
935        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
936        \K is "not well defined" if used in an assertion. PCRE now accepts it if
937        the assertion is positive, but not if it is negative.
939    12. Change 11 fortuitously reduced the size of the stack frame used in the
940        "match()" function of pcre_exec.c by one pointer. Forthcoming
941        implementation of support for (*MARK) will need an extra pointer on the
942        stack; I have reserved it now, so that the stack frame size does not
943        decrease.
945    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
946        item in branch that calls a recursion is a subroutine call - as in the
947        second branch in the above example - was incorrectly given the compile-
948        time error "recursive call could loop indefinitely" because pcre_compile()
949        was not correctly checking the subroutine for matching a non-empty string.
951    14. The checks for overrunning compiling workspace could trigger after an
952        overrun had occurred. This is a "should never occur" error, but it can be
953        triggered by pathological patterns such as hundreds of nested parentheses.
954        The checks now trigger 100 bytes before the end of the workspace.
956    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
959    Version 8.01 19-Jan-2010
960    ------------------------
962    1.  If a pattern contained a conditional subpattern with only one branch (in
963        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
964        computed the wrong minimum data length (which is of course zero for such
965        subpatterns). This could cause incorrect "no match" results.
967    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
968        the pattern is reset in the first branch, pcre_compile() failed with
969        "internal error: code overflow at offset...". This happened only when
970        the reset was to the original external option setting. (An optimization
971        abstracts leading options settings into an external setting, which was the
972        cause of this.)
974    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
975        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
976        assertion pattern did not match (meaning that the assertion was true), it
977        was incorrectly treated as false if the SKIP had been reached during the
978        matching. This also applied to assertions used as conditions.
980    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
981        assertion subpattern, including such a pattern used as a condition,
982        unpredictable results occurred, instead of the error return
985    5.  The C++ GlobalReplace function was not working like Perl for the special
986        situation when an empty string is matched. It now does the fancy magic
987        stuff that is necessary.
989    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
990        removed. (These were left over from very, very early versions of PCRE.)
992    7.  Some cosmetic changes to the code to make life easier when compiling it
993        as part of something else:
995        (a) Change DEBUG to PCRE_DEBUG.
997        (b) In pcre_compile(), rename the member of the "branch_chain" structure
998            called "current" as "current_branch", to prevent a collision with the
999            Linux macro when compiled as a kernel module.
1001        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
1002            prevent a collision with the Linux macro when compiled as a kernel
1003            module.
1005    8.  In pcre_compile() there are some checks for integer overflows that used to
1006        cast potentially large values to (double). This has been changed to that
1007        when building, a check for int64_t is made, and if it is found, it is used
1008        instead, thus avoiding the use of floating point arithmetic. (There is no
1009        other use of FP in PCRE.) If int64_t is not found, the fallback is to
1010        double.
1012    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
1013        2005 (difference between two addresses compared to an unsigned value).
1015    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
1016        custom one, because of the following reported problem in Windows:
1018          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
1019              under Win32.
1020          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
1021              therefore missing the function definition.
1022          - The compiler thus generates a "C" signature for the test function.
1023          - The linker fails to find the "C" function.
1024          - PCRE fails to configure if asked to do so against libbz2.
1026    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
1027        messages were output:
1029          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
1030          rerunning libtoolize, to keep the correct libtool macros in-tree.
1031          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
1033        I have done both of these things.
1035    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
1036        most of the time, it *can* run out if it is given a pattern that contains a
1037        runaway infinite recursion. I updated the discussion in the pcrestack man
1038        page.
1040    13. Now that we have gone to the x.xx style of version numbers, the minor
1041        version may start with zero. Using 08 or 09 is a bad idea because users
1042        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
1043        interpreted as invalid octal numbers. I've updated the previous comment in
1044        configure.ac, and also added a check that gives an error if 08 or 09 are
1045        used.
1047    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
1048        causing partial matching to fail when the end of the subject matched \W
1049        in a UTF-8 pattern where \W was quantified with a minimum of 3.
1051    15. There were some discrepancies between the declarations in pcre_internal.h
1052        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
1053        their definitions. The declarations used "const uschar *" and the
1054        definitions used USPTR. Even though USPTR is normally defined as "const
1055        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
1056        reported that: "This difference in casting confuses some C++ compilers, for
1057        example, SunCC recognizes above declarations as different functions and
1058        generates broken code for hbpcre." I have changed the declarations to use
1059        USPTR.
1061    16. GNU libtool is named differently on some systems. The autogen.sh script now
1062        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
1063        (FreeBSD).
1065    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
1066        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
1067        comment: "Figure out how to create a longlong from a string: strtoll and
1068        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
1069        instance, but it only takes 2 args instead of 3!"
1071    18. A subtle bug concerned with back references has been fixed by a change of
1072        specification, with a corresponding code fix. A pattern such as
1073        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
1074        refers, was giving matches when it shouldn't. For example, xa=xaaa would
1075        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
1076        same bug. Such groups have to be quantified to be useful, or contained
1077        inside another quantified group. (If there's no repetition, the reference
1078        can never match.) The problem arises because, having left the group and
1079        moved on to the rest of the pattern, a later failure that backtracks into
1080        the group uses the captured value from the final iteration of the group
1081        rather than the correct earlier one. I have fixed this in PCRE by forcing
1082        any group that contains a reference to itself to be an atomic group; that
1083        is, there cannot be any backtracking into it once it has completed. This is
1084        similar to recursive and subroutine calls.
1087    Version 8.00 19-Oct-09
1088  ----------------------  ----------------------
1090  1.  The table for translating pcre_compile() error codes into POSIX error codes  1.  The table for translating pcre_compile() error codes into POSIX error codes
1091      was out-of-date, and there was no check on the pcre_compile() error code      was out-of-date, and there was no check on the pcre_compile() error code
1092      being within the table. This could lead to an OK return being given in      being within the table. This could lead to an OK return being given in
1093      error.      error.
1095    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
1096        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
1097        in a Windows environment.
1099    3.  The pcregrep --count option prints the count for each file even when it is
1100        zero, as does GNU grep. However, pcregrep was also printing all files when
1101        --files-with-matches was added. Now, when both options are given, it prints
1102        counts only for those files that have at least one match. (GNU grep just
1103        prints the file name in this circumstance, but including the count seems
1104        more useful - otherwise, why use --count?) Also ensured that the
1105        combination -clh just lists non-zero counts, with no names.
1107    4.  The long form of the pcregrep -F option was incorrectly implemented as
1108        --fixed_strings instead of --fixed-strings. This is an incompatible change,
1109        but it seems right to fix it, and I didn't think it was worth preserving
1110        the old behaviour.
1112    5.  The command line items --regex=pattern and --regexp=pattern were not
1113        recognized by pcregrep, which required --regex pattern or --regexp pattern
1114        (with a space rather than an '='). The man page documented the '=' forms,
1115        which are compatible with GNU grep; these now work.
1117    6.  No libpcreposix.pc file was created for pkg-config; there was just
1118        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
1120    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
1121        when UCP support is not needed, by modifying the Python script that
1122        generates it from Unicode data files. This should not matter if the module
1123        is correctly used as a library, but I received one complaint about 50K of
1124        unwanted data. My guess is that the person linked everything into his
1125        program rather than using a library. Anyway, it does no harm.
1127    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
1128        was a minimum greater than 1 for a wide character in a possessive
1129        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
1130        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
1131        character. Chaos in the form of incorrect output or a compiling loop could
1132        result.
1134    9.  The restrictions on what a pattern can contain when partial matching is
1135        requested for pcre_exec() have been removed. All patterns can now be
1136        partially matched by this function. In addition, if there are at least two
1137        slots in the offset vector, the offset of the earliest inspected character
1138        for the match and the offset of the end of the subject are set in them when
1139        PCRE_ERROR_PARTIAL is returned.
1141    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
1142        synonymous with PCRE_PARTIAL, for backwards compatibility, and
1143        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
1144        and may be more useful for multi-segment matching.
1146    11. Partial matching with pcre_exec() is now more intuitive. A partial match
1147        used to be given if ever the end of the subject was reached; now it is
1148        given only if matching could not proceed because another character was
1149        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
1150        string "Z", which now yields "no match" instead of "partial match". In the
1151        case of pcre_dfa_exec(), "no match" is given if every matching path for the
1152        final character ended with (*FAIL).
1154    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
1155        if the pattern had a "must contain" character that was already found in the
1156        earlier partial match, unless partial matching was again requested. For
1157        example, with the pattern /dog.(body)?/, the "must contain" character is
1158        "g". If the first part-match was for the string "dog", restarting with
1159        "sbody" failed. This bug has been fixed.
1161    13. The string returned by pcre_dfa_exec() after a partial match has been
1162        changed so that it starts at the first inspected character rather than the
1163        first character of the match. This makes a difference only if the pattern
1164        starts with a lookbehind assertion or \b or \B (\K is not supported by
1165        pcre_dfa_exec()). It's an incompatible change, but it makes the two
1166        matching functions compatible, and I think it's the right thing to do.
1168    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
1169        so that the demonstration program is easily available in environments where
1170        PCRE has not been installed from source.
1172    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
1173        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
1174        library.
1176    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
1177        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
1178        is not the first non-POSIX option to be added. Clearly some people find
1179        these options useful.
1181    17. If a caller to the POSIX matching function regexec() passes a non-zero
1182        value for nmatch with a NULL value for pmatch, the value of
1183        nmatch is forced to zero.
1185    18. RunGrepTest did not have a test for the availability of the -u option of
1186        the diff command, as RunTest does. It now checks in the same way as
1187        RunTest, and also checks for the -b option.
1189    19. If an odd number of negated classes containing just a single character
1190        interposed, within parentheses, between a forward reference to a named
1191        subpattern and the definition of the subpattern, compilation crashed with
1192        an internal error, complaining that it could not find the referenced
1193        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
1194        [The bug was that it was starting one character too far in when skipping
1195        over the character class, thus treating the ] as data rather than
1196        terminating the class. This meant it could skip too much.]
1198    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
1199        /g option in pcretest when the pattern contains \K, which makes it possible
1200        to have an empty string match not at the start, even when the pattern is
1201        anchored. Updated pcretest and pcredemo to use this option.
1203    21. If the maximum number of capturing subpatterns in a recursion was greater
1204        than the maximum at the outer level, the higher number was returned, but
1205        with unset values at the outer level. The correct (outer level) value is
1206        now given.
1208    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
1209        PCRE did not set those parentheses (unlike Perl). I have now found a way to
1210        make it do so. The string so far is captured, making this feature
1211        compatible with Perl.
1213    23. The tests have been re-organized, adding tests 11 and 12, to make it
1214        possible to check the Perl 5.10 features against Perl 5.10.
1216    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
1217        pattern matches a fixed length string. PCRE did not allow this; now it
1218        does. Neither allows recursion.
1220    25. I finally figured out how to implement a request to provide the minimum
1221        length of subject string that was needed in order to match a given pattern.
1222        (It was back references and recursion that I had previously got hung up
1223        on.) This code has now been added to pcre_study(); it finds a lower bound
1224        to the length of subject needed. It is not necessarily the greatest lower
1225        bound, but using it to avoid searching strings that are too short does give
1226        some useful speed-ups. The value is available to calling programs via
1227        pcre_fullinfo().
1229    26. While implementing 25, I discovered to my embarrassment that pcretest had
1230        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
1231        study optimizations had never been tested with that matching function.
1232        Oops. What is worse, even when it was passed study data, there was a bug in
1233        pcre_dfa_exec() that meant it never actually used it. Double oops. There
1234        were also very few tests of studied patterns with pcre_dfa_exec().
1236    27. If (?| is used to create subpatterns with duplicate numbers, they are now
1237        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
1238        on the other side of the coin, they are no longer allowed to have different
1239        names, because these cannot be distinguished in PCRE, and this has caused
1240        confusion. (This is a difference from Perl.)
1242    28. When duplicate subpattern names are present (necessarily with different
1243        numbers, as required by 27 above), and a test is made by name in a
1244        conditional pattern, either for a subpattern having been matched, or for
1245        recursion in such a pattern, all the associated numbered subpatterns are
1246        tested, and the overall condition is true if the condition is true for any
1247        one of them. This is the way Perl works, and is also more like the way
1248        testing by number works.
1251  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09
1252  ---------------------  ---------------------

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