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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 8.10 16-Jun-2010  Version 8.32
5    ------------
7    1.  Improved JIT compiler optimizations for first character search and single
8        character iterators.
10    2.  Supporting IBM XL C compilers for PPC architectures in the JIT compiler.
11        Patch by Daniel Richard G.
13    3.  Single character iterator optimizations in the JIT compiler.
15    4.  Improved JIT compiler optimizations for character ranges.
17    5.  Rename the "leave" variable names to "quit" to improve WinCE compatibility.
18        Reported by Giuseppe D'Angelo.
20    6.  The PCRE_STARTLINE bit, indicating that a match can occur only at the start
21        of a line, was being set incorrectly in cases where .* appeared inside
22        atomic brackets at the start of a pattern, or where there was a subsequent
23        *PRUNE or *SKIP.
25    7.  Improved instruction cache flush for POWER/PowerPC.
26        Patch by Daniel Richard G.
28    8.  Fixed a number of issues in pcregrep, making it more compatible with GNU
29        grep:
31        (a) There is now no limit to the number of patterns to be matched.
33        (b) An error is given if a pattern is too long.
35        (c) Multiple uses of --exclude, --exclude-dir, --include, and --include-dir
36            are now supported.
38        (d) --exclude-from and --include-from (multiple use) have been added.
40        (e) Exclusions and inclusions now apply to all files and directories, not
41            just to those obtained from scanning a directory recursively.
43        (f) Multiple uses of -f and --file-list are now supported.
45        (g) In a Windows environment, the default for -d has been changed from
46            "read" (the GNU grep default) to "skip", because otherwise the presence
47            of a directory in the file list provokes an error.
49        (h) The documentation has been revised and clarified in places.
51    9.  Improve the matching speed of capturing brackets.
53    10. Changed the meaning of \X so that it now matches a Unicode extended
54        grapheme cluster.
56    11. Patch by Daniel Richard G to the autoconf files to add a macro for sorting
57        out POSIX threads when JIT support is configured.
61    Version 8.31 06-July-2012
62    -------------------------
64    1.  Fixing a wrong JIT test case and some compiler warnings.
66    2.  Removed a bashism from the RunTest script.
68    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
69        to unsigned type, result still unsigned" that was given by an MS compiler
70        on encountering the code "-sizeof(xxx)".
72    4.  Partial matching support is added to the JIT compiler.
74    5.  Fixed several bugs concerned with partial matching of items that consist
75        of more than one character:
77        (a) /^(..)\1/ did not partially match "aba" because checking references was
78            done on an "all or nothing" basis. This also applied to repeated
79            references.
81        (b) \R did not give a hard partial match if \r was found at the end of the
82            subject.
84        (c) \X did not give a hard partial match after matching one or more
85            characters at the end of the subject.
87        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
88            a partial match for the string "\r".
90        (e) When newline was set to CRLF, the metacharacter "." did not recognize
91            a partial match for a CR character at the end of the subject string.
93    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
94        running pcretest, the text "(JIT)" added to the output whenever JIT is
95        actually used to run the match.
97    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
98        or /S+[+] with a digit between 1 and 7.
100    8.  OP_NOT now supports any UTF character not just single-byte ones.
102    9.  (*MARK) control verb is now supported by the JIT compiler.
104    10. The command "./RunTest list" lists the available tests without actually
105        running any of them. (Because I keep forgetting what they all are.)
109    12. Applied a (slightly modified) user-supplied patch that improves performance
110        when the heap is used for recursion (compiled with --disable-stack-for-
111        recursion). Instead of malloc and free for each heap frame each time a
112        logical recursion happens, frames are retained on a chain and re-used where
113        possible. This sometimes gives as much as 30% improvement.
115    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
116        call.
118    14. As documented, (*COMMIT) is now confined to within a positive assertion.
120    15. It is now possible to link pcretest with libedit as an alternative to
121        libreadline.
123    16. (*COMMIT) control verb is now supported by the JIT compiler.
125    17. The Unicode data tables have been updated to Unicode 6.1.0.
127    18. Added --file-list option to pcregrep.
129    19. Added binary file support to pcregrep, including the -a, --binary-files,
130        -I, and --text options.
132    20. The madvise function is renamed for posix_madvise for QNX compatibility
133        reasons. Fixed by Giuseppe D'Angelo.
135    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
137    22. Changed the option for creating symbolic links for 16-bit man pages from
138        -s to -sf so that re-installing does not cause issues.
140    23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.
142    24. Fixed a very old bug in pcretest that caused errors with restarted DFA
143        matches in certain environments (the workspace was not being correctly
144        retained). Also added to pcre_dfa_exec() a simple plausibility check on
145        some of the workspace data at the beginning of a restart.
147    25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
148        was not doing so when it should - probably a typo introduced by SVN 528
149        (change 8.10/14).
151    26. When PCRE_UCP was not set, \w+\x{c4} was incorrectly auto-possessifying the
152        \w+ when the character tables indicated that \x{c4} was a word character.
153        There were several related cases, all because the tests for doing a table
154        lookup were testing for characters less than 127 instead of 255.
156    27. If a pattern contains capturing parentheses that are not used in a match,
157        their slots in the ovector are set to -1. For those that are higher than
158        any matched groups, this happens at the end of processing. In the case when
159        there were back references that the ovector was too small to contain
160        (causing temporary malloc'd memory to be used during matching), and the
161        highest capturing number was not used, memory off the end of the ovector
162        was incorrectly being set to -1. (It was using the size of the temporary
163        memory instead of the true size.)
165    28. To catch bugs like 27 using valgrind, when pcretest is asked to specify an
166        ovector size, it uses memory at the end of the block that it has got.
168    29. Check for an overlong MARK name and give an error at compile time. The
169        limit is 255 for the 8-bit library and 65535 for the 16-bit library.
171    30. JIT compiler update.
173    31. JIT is now supported on jailbroken iOS devices. Thanks for Ruiger
174        Rill for the patch.
176    32. Put spaces around SLJIT_PRINT_D in the JIT compiler. Required by CXX11.
178    33. Variable renamings in the PCRE-JIT compiler. No functionality change.
180    34. Fixed typos in pcregrep: in two places there was SUPPORT_LIBZ2 instead of
181        SUPPORT_LIBBZ2. This caused a build problem when bzip2 but not gzip (zlib)
182        was enabled.
184    35. Improve JIT code generation for greedy plus quantifier.
186    36. When /((?:a?)*)*c/ or /((?>a?)*)*c/ was matched against "aac", it set group
187        1 to "aa" instead of to an empty string. The bug affected repeated groups
188        that could potentially match an empty string.
190    37. Optimizing single character iterators in JIT.
192    38. Wide characters specified with \uxxxx in JavaScript mode are now subject to
193        the same checks as \x{...} characters in non-JavaScript mode. Specifically,
194        codepoints that are too big for the mode are faulted, and in a UTF mode,
195        disallowed codepoints are also faulted.
197    39. If PCRE was compiled with UTF support, in three places in the DFA
198        matcher there was code that should only have been obeyed in UTF mode, but
199        was being obeyed unconditionally. In 8-bit mode this could cause incorrect
200        processing when bytes with values greater than 127 were present. In 16-bit
201        mode the bug would be provoked by values in the range 0xfc00 to 0xdc00. In
202        both cases the values are those that cannot be the first data item in a UTF
203        character. The three items that might have provoked this were recursions,
204        possessively repeated groups, and atomic groups.
206    40. Ensure that libpcre is explicitly listed in the link commands for pcretest
207        and pcregrep, because some OS require shared objects to be explicitly
208        passed to ld, causing the link step to fail if they are not.
210    41. There were two incorrect #ifdefs in pcre_study.c, meaning that, in 16-bit
211        mode, patterns that started with \h* or \R* might be incorrectly matched.
214    Version 8.30 04-February-2012
215    -----------------------------
217    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
218        name is defined in ctype.h.
220    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
221        only in quite long subpatterns.
223    3.  Removed the function pcre_info(), which has been obsolete and deprecated
224        since it was replaced by pcre_fullinfo() in February 2000.
226    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
227        match a (*MARK), and the match failed at the start of the subject, a
228        reference to memory before the start of the subject could occur. This bug
229        was introduced by fix 17 of release 8.21.
231    5.  A reference to an unset group with zero minimum repetition was giving
232        totally wrong answers (in non-JavaScript-compatibility mode). For example,
233        /(another)?(\1?)test/ matched against "hello world test". This bug was
234        introduced in release 8.13.
236    6.  Add support for 16-bit character strings (a large amount of work involving
237        many changes and refactorings).
239    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
240        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
241        from a file.
243    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
244        rounding is not applied in this particular case).
246    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
247        if they appear, or are escaped, in patterns.
249    10. Get rid of a number of -Wunused-but-set-variable warnings.
251    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
252        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
253        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
254        also returns the mark "x". This bug applied to capturing parentheses,
255        non-capturing parentheses, and atomic parentheses. It also applied to some
256        assertions.
258    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
259        information out of configure.ac instead of relying on pcre.h.generic, which
260        is not stored in the repository.
262    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
263        -lreadline.
265    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
267    15. Applied Graycode's patch to put the top-level frame on the stack rather
268        than the heap when not using the stack for recursion. This gives a
269        performance improvement in many cases when recursion is not deep.
271    16. Experimental code added to "pcretest -C" to output the stack frame size.
274    Version 8.21 12-Dec-2011
275    ------------------------
277    1.  Updating the JIT compiler.
279    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
280        are added as well.
282    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
283        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
284        calling _pcre_jit_exec. Some extra comments are added.
286    4.  (*MARK) settings inside atomic groups that do not contain any capturing
287        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
288        was introduced by change 18 for 8.20.
290    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
291        ECMA-262 standard.
293    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
294        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
295        This bug was probably introduced by change 9 of 8.13.
297    7.  While fixing 6 above, I noticed that a number of other items were being
298        incorrectly rejected as "not fixed length". This arose partly because newer
299        opcodes had not been added to the fixed-length checking code. I have (a)
300        corrected the bug and added tests for these items, and (b) arranged for an
301        error to occur if an unknown opcode is encountered while checking for fixed
302        length instead of just assuming "not fixed length". The items that were
303        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
304        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
305        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
307    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
308        being incorrectly compiled and would have given unpredicatble results.
310    9.  A possessively repeated subpattern with minimum repeat count greater than
311        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
312        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
313        the first (A) could occur when it should not.
315    10. Add a cast and remove a redundant test from the code.
317    11. JIT should use pcre_malloc/pcre_free for allocation.
319    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
320        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
321        is anything other than /usr, -L is still shown).
323    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
325    14. Perl does not support \N without a following name in a [] class; PCRE now
326        also gives an error.
328    15. If a forward reference was repeated with an upper limit of around 2000,
329        it caused the error "internal error: overran compiling workspace". The
330        maximum number of forward references (including repeats) was limited by the
331        internal workspace, and dependent on the LINK_SIZE. The code has been
332        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
333        the default depends on LINK_SIZE. There is a new upper limit (for safety)
334        of around 200,000 forward references. While doing this, I also speeded up
335        the filling in of repeated forward references.
337    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
338        incorrectly expecting the subject to contain another "a" after the start.
340    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
341        in the match, the SKIP should be ignored. This was not happening; instead
342        the SKIP was being treated as NOMATCH. For patterns such as
343        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
344        tested.
346    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
347        now much more compatible with Perl, in particular in cases where the result
348        is a non-match for a non-anchored pattern. For example, if
349        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
350        "m", where previously it did not return a name. A side effect of this
351        change is that for partial matches, the last encountered mark name is
352        returned, as for non matches. A number of tests that were previously not
353        Perl-compatible have been moved into the Perl-compatible test files. The
354        refactoring has had the pleasing side effect of removing one argument from
355        the match() function, thus reducing its stack requirements.
357    19. If the /S+ option was used in pcretest to study a pattern using JIT,
358        subsequent uses of /S (without +) incorrectly behaved like /S+.
360    21. Retrieve executable code size support for the JIT compiler and fixing
361        some warnings.
363    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
364        not work when the shorter character appeared right at the end of the
365        subject string.
367    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
368        systems.
370    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
371        output it when the /M option is used in pcretest.
373    25. The CheckMan script was not being included in the distribution. Also, added
374        an explicit "perl" to run Perl scripts from the PrepareRelease script
375        because this is reportedly needed in Windows.
377    26. If study data was being save in a file and studying had not found a set of
378        "starts with" bytes for the pattern, the data written to the file (though
379        never used) was taken from uninitialized memory and so caused valgrind to
380        complain.
382    27. Updated RunTest.bat as provided by Sheri Pierce.
384    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
386    29. Computation of memory usage for the table of capturing group names was
387        giving an unnecessarily large value.
390    Version 8.20 21-Oct-2011
391    ------------------------
393    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
394        a POSIX class. After further experiments with Perl, which convinced me that
395        Perl has bugs and confusions, a closing square bracket is no longer allowed
396        in a POSIX name. This bug also affected patterns with classes that started
397        with full stops.
399    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
400        captured substring, but while checking the failing first alternative,
401        substring 1 is temporarily captured. If the output vector supplied to
402        pcre_exec() was not big enough for this capture, the yield of the function
403        was still zero ("insufficient space for captured substrings"). This cannot
404        be totally fixed without adding another stack variable, which seems a lot
405        of expense for a edge case. However, I have improved the situation in cases
406        such as /(a)(b)x|abc/ matched against "abc", where the return code
407        indicates that fewer than the maximum number of slots in the ovector have
408        been set.
410    3.  Related to (2) above: when there are more back references in a pattern than
411        slots in the output vector, pcre_exec() uses temporary memory during
412        matching, and copies in the captures as far as possible afterwards. It was
413        using the entire output vector, but this conflicts with the specification
414        that only 2/3 is used for passing back captured substrings. Now it uses
415        only the first 2/3, for compatibility. This is, of course, another edge
416        case.
418    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
419        main code base, and can be used by building with --enable-jit. When this is
420        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
421        runtime --no-jit option is given.
423    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
424        ovector, the return from the function was zero, implying that there were
425        other matches that did not fit. The correct "exactly full" value is now
426        returned.
428    6.  If a subpattern that was called recursively or as a subroutine contained
429        (*PRUNE) or any other control that caused it to give a non-standard return,
430        invalid errors such as "Error -26 (nested recursion at the same subject
431        position)" or even infinite loops could occur.
433    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
434        computing the minimum length on reaching *ACCEPT, and so ended up with the
435        wrong value of 1 rather than 0. Further investigation indicates that
436        computing a minimum subject length in the presence of *ACCEPT is difficult
437        (think back references, subroutine calls), and so I have changed the code
438        so that no minimum is registered for a pattern that contains *ACCEPT.
440    8.  If (*THEN) was present in the first (true) branch of a conditional group,
441        it was not handled as intended. [But see 16 below.]
443    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
444        Sheri Pierce.
446    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
447        the first byte in a match must be "a".
449    11. Change 17 for 8.13 increased the recursion depth for patterns like
450        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
451        pattern contains any instances of (*THEN). If it does not, the old
452        optimizations are restored. It would be nice to do this on a per-group
453        basis, but at the moment that is not feasible.
455    12. In some environments, the output of pcretest -C is CRLF terminated. This
456        broke RunTest's code that checks for the link size. A single white space
457        character after the value is now allowed for.
459    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
460        For "fr", it uses the Windows-specific input and output files.
462    14. If (*THEN) appeared in a group that was called recursively or as a
463        subroutine, it did not work as intended. [But see next item.]
465    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
466        pattern fragments (but not containing any | characters). If A and B are
467        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
468        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
469        D. In other words, Perl considers parentheses that do not contain any |
470        characters to be part of a surrounding alternative, whereas PCRE was
471        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
472        differently. PCRE now behaves in the same way as Perl, except in the case
473        of subroutine/recursion calls such as (?1) which have in any case always
474        been different (but PCRE had them first :-).
476    16. Related to 15 above: Perl does not treat the | in a conditional group as
477        creating alternatives. Such a group is treated in the same way as an
478        ordinary group without any | characters when processing (*THEN). PCRE has
479        been changed to match Perl's behaviour.
481    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
482        RunGrepTest script failed.
484    18. Change 22 for version 13 caused atomic groups to use more stack. This is
485        inevitable for groups that contain captures, but it can lead to a lot of
486        stack use in large patterns. The old behaviour has been restored for atomic
487        groups that do not contain any capturing parentheses.
489    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
490        suppress the check for a minimum subject length at run time. (If it was
491        given to pcre_exec() or pcre_dfa_exec() it did work.)
493    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
494        fail to work when decoding hex characters in data strings in EBCDIC
495        environments.
497    21. It appears that in at least one Mac OS environment, the isxdigit() function
498        is implemented as a macro that evaluates to its argument more than once,
499        contravening the C 90 Standard (I haven't checked a later standard). There
500        was an instance in pcretest which caused it to go wrong when processing
501        \x{...} escapes in subject strings. The has been rewritten to avoid using
502        things like p++ in the argument of isxdigit().
505    Version 8.13 16-Aug-2011
506    ------------------------
508    1.  The Unicode data tables have been updated to Unicode 6.0.0.
510    2.  Two minor typos in pcre_internal.h have been fixed.
512    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
513        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
514        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
516    4.  There were a number of related bugs in the code for matching backrefences
517        caselessly in UTF-8 mode when codes for the characters concerned were
518        different numbers of bytes. For example, U+023A and U+2C65 are an upper
519        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
520        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
521        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
522        2-byte code at the end of the subject (it thought there wasn't enough data
523        left).
525    5.  Comprehensive information about what went wrong is now returned by
526        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
527        as the output vector has at least 2 elements. The offset of the start of
528        the failing character and a reason code are placed in the vector.
530    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
531        now returned is for the first byte of the failing character, instead of the
532        last byte inspected. This is an incompatible change, but I hope it is small
533        enough not to be a problem. It makes the returned offset consistent with
534        pcre_exec() and pcre_dfa_exec().
536    7.  pcretest now gives a text phrase as well as the error number when
537        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
538        failure, the offset and reason code are output.
540    8.  When \R was used with a maximizing quantifier it failed to skip backwards
541        over a \r\n pair if the subsequent match failed. Instead, it just skipped
542        back over a single character (\n). This seems wrong (because it treated the
543        two characters as a single entity when going forwards), conflicts with the
544        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
545        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
546        has been changed.
548    9.  Some internal refactoring has changed the processing so that the handling
549        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
550        time (the PCRE_DOTALL option was changed this way some time ago: version
551        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
552        which was always a bit of a fudge. It also means that there is one less
553        argument for the match() function, which reduces its stack requirements
554        slightly. This change also fixes an incompatibility with Perl: the pattern
555        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
557    10. More internal refactoring has drastically reduced the number of recursive
558        calls to match() for possessively repeated groups such as (abc)++ when
559        using pcre_exec().
561    11. While implementing 10, a number of bugs in the handling of groups were
562        discovered and fixed:
564        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
565        (a|)*(?1) gave a compile-time internal error.
566        ((a|)+)+  did not notice that the outer group could match an empty string.
567        (^a|^)+   was not marked as anchored.
568        (.*a|.*)+ was not marked as matching at start or after a newline.
570    12. Yet more internal refactoring has removed another argument from the match()
571        function. Special calls to this function are now indicated by setting a
572        value in a variable in the "match data" data block.
574    13. Be more explicit in pcre_study() instead of relying on "default" for
575        opcodes that mean there is no starting character; this means that when new
576        ones are added and accidentally left out of pcre_study(), testing should
577        pick them up.
579    14. The -s option of pcretest has been documented for ages as being an old
580        synonym of -m (show memory usage). I have changed it to mean "force study
581        for every regex", that is, assume /S for every regex. This is similar to -i
582        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
583        using it. It makes it easier to run collections of tests with and without
584        study enabled, and thereby test pcre_study() more easily. All the standard
585        tests are now run with and without -s (but some patterns can be marked as
586        "never study" - see 20 below).
588    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
589        restoration of the capturing data to the outer values was not happening
590        correctly.
592    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
593        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
594        pattern had matched an empty string, and so incorrectly returned a no
595        match.
597    17. There was optimizing code for the last branch of non-capturing parentheses,
598        and also for the obeyed branch of a conditional subexpression, which used
599        tail recursion to cut down on stack usage. Unfortunately, now that there is
600        the possibility of (*THEN) occurring in these branches, tail recursion is
601        no longer possible because the return has to be checked for (*THEN). These
602        two optimizations have therefore been removed. [But see 8.20/11 above.]
604    18. If a pattern containing \R was studied, it was assumed that \R always
605        matched two bytes, thus causing the minimum subject length to be
606        incorrectly computed because \R can also match just one byte.
608    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
609        was incorrectly computed.
611    20. If /S is present twice on a test pattern in pcretest input, it now
612        *disables* studying, thereby overriding the use of -s on the command line
613        (see 14 above). This is necessary for one or two tests to keep the output
614        identical in both cases.
616    21. When (*ACCEPT) was used in an assertion that matched an empty string and
617        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
619    22. When an atomic group that contained a capturing parenthesis was
620        successfully matched, but the branch in which it appeared failed, the
621        capturing was not being forgotten if a higher numbered group was later
622        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
623        group 1 to "a", when in fact it should be unset. This applied to multi-
624        branched capturing and non-capturing groups, repeated or not, and also to
625        positive assertions (capturing in negative assertions does not happen
626        in PCRE) and also to nested atomic groups.
628    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
629        subject after a captured substring, to make it easier to tell which of a
630        number of identical substrings has been captured.
632    24. The way atomic groups are processed by pcre_exec() has been changed so that
633        if they are repeated, backtracking one repetition now resets captured
634        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
635        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
636        "aaa". Previously, it would have been "a". As part of this code
637        refactoring, the way recursive calls are handled has also been changed.
639    25. If an assertion condition captured any substrings, they were not passed
640        back unless some other capturing happened later. For example, if
641        (?(?=(a))a) was matched against "a", no capturing was returned.
643    26. When studying a pattern that contained subroutine calls or assertions,
644        the code for finding the minimum length of a possible match was handling
645        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
646        group 1 called group 2 while simultaneously a separate group 2 called group
647        1). A stack overflow occurred in this case. I have fixed this by limiting
648        the recursion depth to 10.
650    27. Updated RunTest.bat in the distribution to the version supplied by Tom
651        Fortmann. This supports explicit test numbers on the command line, and has
652        argument validation and error reporting.
654    28. An instance of \X with an unlimited repeat could fail if at any point the
655        first character it looked at was a mark character.
657    29. Some minor code refactoring concerning Unicode properties and scripts
658        should reduce the stack requirement of match() slightly.
660    30. Added the '=' option to pcretest to check the setting of unused capturing
661        slots at the end of the pattern, which are documented as being -1, but are
662        not included in the return count.
664    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
665        compiled something random. Now it gives a compile-time error (as does
666        Perl).
668    32. A *MARK encountered during the processing of a positive assertion is now
669        recorded and passed back (compatible with Perl).
671    33. If --only-matching or --colour was set on a pcregrep call whose pattern
672        had alternative anchored branches, the search for a second match in a line
673        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
674        matched the line "0102" twice. The same bug affected patterns that started
675        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
676        twice.
678    34. Previously, PCRE did not allow quantification of assertions. However, Perl
679        does, and because of capturing effects, quantifying parenthesized
680        assertions may at times be useful. Quantifiers are now allowed for
681        parenthesized assertions.
683    35. A minor code tidy in pcre_compile() when checking options for \R usage.
685    36. \g was being checked for fancy things in a character class, when it should
686        just be a literal "g".
688    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
689        appearance of a nested POSIX class supersedes an apparent external class.
690        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
691        unescaped square brackets may also appear as part of class names. For
692        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
693        more like Perl. (But see 8.20/1 above.)
695    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
696        was because it thought it was \N{name}, which is not supported).
698    39. Add minix to OS list not supporting the -S option in pcretest.
700    40. PCRE tries to detect cases of infinite recursion at compile time, but it
701        cannot analyze patterns in sufficient detail to catch mutual recursions
702        such as ((?1))((?2)). There is now a runtime test that gives an error if a
703        subgroup is called recursively as a subpattern for a second time at the
704        same position in the subject string. In previous releases this might have
705        been caught by the recursion limit, or it might have run out of stack.
707    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
708        happen only once. PCRE was, however incorrectly giving a compile time error
709        "recursive call could loop indefinitely" because it cannot analyze the
710        pattern in sufficient detail. The compile time test no longer happens when
711        PCRE is compiling a conditional subpattern, but actual runaway loops are
712        now caught at runtime (see 40 above).
714    42. It seems that Perl allows any characters other than a closing parenthesis
715        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
716        has been changed to be the same.
718    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
719        as not to get warnings when autogen.sh is called. Also changed
720        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
722    44. To help people who use pcregrep to scan files containing exceedingly long
723        lines, the following changes have been made:
725        (a) The default value of the buffer size parameter has been increased from
726            8K to 20K. (The actual buffer used is three times this size.)
728        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
729            PCRE is built.
731        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
732            to be set at run time.
734        (d) Numerical values in pcregrep options can be followed by K or M, for
735            example --buffer-size=50K.
737        (e) If a line being scanned overflows pcregrep's buffer, an error is now
738            given and the return code is set to 2.
740    45. Add a pointer to the latest mark to the callout data block.
742    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
743        partial match of an empty string instead of no match. This was specific to
744        the use of ".".
746    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
747        complete match instead of a partial match. This bug was dependent on both
748        the PCRE_UTF8 and PCRE_DOTALL options being set.
750    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
751        starting byte set, because \b was not being ignored.
754    Version 8.12 15-Jan-2011
755    ------------------------
757    1.  Fixed some typos in the markup of the man pages, and wrote a script that
758        checks for such things as part of the documentation building process.
760    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
761        --match-limit and --recursion-limit options (added for 8.11). In
762        particular, this made one of the standard tests fail. (The integer value
763        went into the wrong half of a long int.)
765    3.  If the --colour option was given to pcregrep with -v (invert match), it
766        did strange things, either producing crazy output, or crashing. It should,
767        of course, ignore a request for colour when reporting lines that do not
768        match.
770    4.  Another pcregrep bug caused similar problems if --colour was specified with
771        -M (multiline) and the pattern match finished with a line ending.
773    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
774        matched in multiline mode, the following line was shown as part of the
775        match. This seems wrong, so I have changed it.
777    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
778        the check for further matches in the same line (so they could be coloured)
779        to overrun the end of the current line. If another match was found, it was
780        incorrectly shown (and then shown again when found in the next line).
782    7.  If pcregrep was compiled under Windows, there was a reference to the
783        function pcregrep_exit() before it was defined. I am assuming this was
784        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
785        reported by a user. I've moved the definition above the reference.
788    Version 8.11 10-Dec-2010
789    ------------------------
791    1.  (*THEN) was not working properly if there were untried alternatives prior
792        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
793        backtracked to try for "b" instead of moving to the next alternative branch
794        at the same level (in this case, to look for "c"). The Perl documentation
795        is clear that when (*THEN) is backtracked onto, it goes to the "next
796        alternative in the innermost enclosing group".
798    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
799        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
800        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
801        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
802        (*THEN).
804    3.  If \s appeared in a character class, it removed the VT character from
805        the class, even if it had been included by some previous item, for example
806        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
807        of \s, but is part of the POSIX "space" class.)
809    4.  A partial match never returns an empty string (because you can always
810        match an empty string at the end of the subject); however the checking for
811        an empty string was starting at the "start of match" point. This has been
812        changed to the "earliest inspected character" point, because the returned
813        data for a partial match starts at this character. This means that, for
814        example, /(?<=abc)def/ gives a partial match for the subject "abc"
815        (previously it gave "no match").
817    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
818        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
819        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
820        has an implication that the given string is incomplete (because a partial
821        match is preferred over a full match). For this reason, these items now
822        give a partial match in this situation. [Aside: previously, the one case
823        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
824        match rather than a full match, which was wrong by the old rules, but is
825        now correct.]
827    6.  There was a bug in the handling of #-introduced comments, recognized when
828        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
829        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
830        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
831        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
832        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
833        places in pcre_compile().
835    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
836        comments when looking ahead for named forward references to subpatterns,
837        the only newline sequence it recognized was NL. It now handles newlines
838        according to the set newline convention.
840    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
841        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
842        cater for a lack of strerror(). These oversights have been fixed.
844    9.  Added --match-limit and --recursion-limit to pcregrep.
846    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
848    11. When the -o option was used, pcregrep was setting a return code of 1, even
849        when matches were found, and --line-buffered was not being honoured.
851    12. Added an optional parentheses number to the -o and --only-matching options
852        of pcregrep.
854    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
855        can match an empty string. The code to do it in pcretest and pcredemo
856        needed fixing:
858        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
859            only one byte after an empty string match just before CRLF (this case
860            just got forgotten; "any" and "anycrlf" were OK).
862        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
863            mode when an empty string match preceded an ASCII character followed by
864            a non-ASCII character. (The code for advancing by one character rather
865            than one byte was nonsense.)
867        (c) The pcredemo.c sample program did not have any code at all to handle
868            the cases when CRLF is a valid newline sequence.
870    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
871        as a starting offset was within the subject string. There is now a new
872        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
873        negative or greater than the length of the string. In order to test this,
874        pcretest is extended to allow the setting of negative starting offsets.
876    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
877        starting offset points to the beginning of a UTF-8 character was
878        unnecessarily clumsy. I tidied it up.
880    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
881        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
883    17. Nobody had reported that the --include_dir option, which was added in
884        release 7.7 should have been called --include-dir (hyphen, not underscore)
885        for compatibility with GNU grep. I have changed it to --include-dir, but
886        left --include_dir as an undocumented synonym, and the same for
887        --exclude-dir, though that is not available in GNU grep, at least as of
888        release 2.5.4.
890    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
891        characters from a string of bytes) have been redefined so as not to use
892        loops, in order to improve performance in some environments. At the same
893        time, I abstracted some of the common code into auxiliary macros to save
894        repetition (this should not affect the compiled code).
896    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
897        compile-time error is now given if \c is not followed by an ASCII
898        character, that is, a byte less than 128. (In EBCDIC mode, the code is
899        different, and any byte value is allowed.)
901    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
902        START_OPTIMIZE option, which is now allowed at compile time - but just
903        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
904        to pcregrep and other applications that have no direct access to PCRE
905        options. The new /Y option in pcretest sets this option when calling
906        pcre_compile().
908    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
909        back references. Groups containing recursive back references were forced to
910        be atomic by that change, but in the case of named groups, the amount of
911        memory required was incorrectly computed, leading to "Failed: internal
912        error: code overflow". This has been fixed.
914    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
915        pcretest.c, to avoid build problems in some Borland environments.
918    Version 8.10 25-Jun-2010
919  ------------------------  ------------------------
921  1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and  1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and

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