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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.
29    Version 8.31 06-July-2012
30    -------------------------
32    1.  Fixing a wrong JIT test case and some compiler warnings.
34    2.  Removed a bashism from the RunTest script.
36    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
37        to unsigned type, result still unsigned" that was given by an MS compiler
38        on encountering the code "-sizeof(xxx)".
40    4.  Partial matching support is added to the JIT compiler.
42    5.  Fixed several bugs concerned with partial matching of items that consist
43        of more than one character:
45        (a) /^(..)\1/ did not partially match "aba" because checking references was
46            done on an "all or nothing" basis. This also applied to repeated
47            references.
49        (b) \R did not give a hard partial match if \r was found at the end of the
50            subject.
52        (c) \X did not give a hard partial match after matching one or more
53            characters at the end of the subject.
55        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
56            a partial match for the string "\r".
58        (e) When newline was set to CRLF, the metacharacter "." did not recognize
59            a partial match for a CR character at the end of the subject string.
61    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
62        running pcretest, the text "(JIT)" added to the output whenever JIT is
63        actually used to run the match.
65    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
66        or /S+[+] with a digit between 1 and 7.
68    8.  OP_NOT now supports any UTF character not just single-byte ones.
70    9.  (*MARK) control verb is now supported by the JIT compiler.
72    10. The command "./RunTest list" lists the available tests without actually
73        running any of them. (Because I keep forgetting what they all are.)
77    12. Applied a (slightly modified) user-supplied patch that improves performance
78        when the heap is used for recursion (compiled with --disable-stack-for-
79        recursion). Instead of malloc and free for each heap frame each time a
80        logical recursion happens, frames are retained on a chain and re-used where
81        possible. This sometimes gives as much as 30% improvement.
83    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
84        call.
86    14. As documented, (*COMMIT) is now confined to within a positive assertion.
88    15. It is now possible to link pcretest with libedit as an alternative to
89        libreadline.
91    16. (*COMMIT) control verb is now supported by the JIT compiler.
93    17. The Unicode data tables have been updated to Unicode 6.1.0.
95    18. Added --file-list option to pcregrep.
97    19. Added binary file support to pcregrep, including the -a, --binary-files,
98        -I, and --text options.
100    20. The madvise function is renamed for posix_madvise for QNX compatibility
101        reasons. Fixed by Giuseppe D'Angelo.
103    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
105    22. Changed the option for creating symbolic links for 16-bit man pages from
106        -s to -sf so that re-installing does not cause issues.
108    23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.
110    24. Fixed a very old bug in pcretest that caused errors with restarted DFA
111        matches in certain environments (the workspace was not being correctly
112        retained). Also added to pcre_dfa_exec() a simple plausibility check on
113        some of the workspace data at the beginning of a restart.
115    25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
116        was not doing so when it should - probably a typo introduced by SVN 528
117        (change 8.10/14).
119    26. When PCRE_UCP was not set, \w+\x{c4} was incorrectly auto-possessifying the
120        \w+ when the character tables indicated that \x{c4} was a word character.
121        There were several related cases, all because the tests for doing a table
122        lookup were testing for characters less than 127 instead of 255.
124    27. If a pattern contains capturing parentheses that are not used in a match,
125        their slots in the ovector are set to -1. For those that are higher than
126        any matched groups, this happens at the end of processing. In the case when
127        there were back references that the ovector was too small to contain
128        (causing temporary malloc'd memory to be used during matching), and the
129        highest capturing number was not used, memory off the end of the ovector
130        was incorrectly being set to -1. (It was using the size of the temporary
131        memory instead of the true size.)
133    28. To catch bugs like 27 using valgrind, when pcretest is asked to specify an
134        ovector size, it uses memory at the end of the block that it has got.
136    29. Check for an overlong MARK name and give an error at compile time. The
137        limit is 255 for the 8-bit library and 65535 for the 16-bit library.
139    30. JIT compiler update.
141    31. JIT is now supported on jailbroken iOS devices. Thanks for Ruiger
142        Rill for the patch.
144    32. Put spaces around SLJIT_PRINT_D in the JIT compiler. Required by CXX11.
146    33. Variable renamings in the PCRE-JIT compiler. No functionality change.
148    34. Fixed typos in pcregrep: in two places there was SUPPORT_LIBZ2 instead of
149        SUPPORT_LIBBZ2. This caused a build problem when bzip2 but not gzip (zlib)
150        was enabled.
152    35. Improve JIT code generation for greedy plus quantifier.
154    36. When /((?:a?)*)*c/ or /((?>a?)*)*c/ was matched against "aac", it set group
155        1 to "aa" instead of to an empty string. The bug affected repeated groups
156        that could potentially match an empty string.
158    37. Optimizing single character iterators in JIT.
160    38. Wide characters specified with \uxxxx in JavaScript mode are now subject to
161        the same checks as \x{...} characters in non-JavaScript mode. Specifically,
162        codepoints that are too big for the mode are faulted, and in a UTF mode,
163        disallowed codepoints are also faulted.
165    39. If PCRE was compiled with UTF support, in three places in the DFA
166        matcher there was code that should only have been obeyed in UTF mode, but
167        was being obeyed unconditionally. In 8-bit mode this could cause incorrect
168        processing when bytes with values greater than 127 were present. In 16-bit
169        mode the bug would be provoked by values in the range 0xfc00 to 0xdc00. In
170        both cases the values are those that cannot be the first data item in a UTF
171        character. The three items that might have provoked this were recursions,
172        possessively repeated groups, and atomic groups.
174    40. Ensure that libpcre is explicitly listed in the link commands for pcretest
175        and pcregrep, because some OS require shared objects to be explicitly
176        passed to ld, causing the link step to fail if they are not.
178    41. There were two incorrect #ifdefs in pcre_study.c, meaning that, in 16-bit
179        mode, patterns that started with \h* or \R* might be incorrectly matched.
182    Version 8.30 04-February-2012
183    -----------------------------
185    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
186        name is defined in ctype.h.
188    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
189        only in quite long subpatterns.
191    3.  Removed the function pcre_info(), which has been obsolete and deprecated
192        since it was replaced by pcre_fullinfo() in February 2000.
194    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
195        match a (*MARK), and the match failed at the start of the subject, a
196        reference to memory before the start of the subject could occur. This bug
197        was introduced by fix 17 of release 8.21.
199    5.  A reference to an unset group with zero minimum repetition was giving
200        totally wrong answers (in non-JavaScript-compatibility mode). For example,
201        /(another)?(\1?)test/ matched against "hello world test". This bug was
202        introduced in release 8.13.
204    6.  Add support for 16-bit character strings (a large amount of work involving
205        many changes and refactorings).
207    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
208        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
209        from a file.
211    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
212        rounding is not applied in this particular case).
214    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
215        if they appear, or are escaped, in patterns.
217    10. Get rid of a number of -Wunused-but-set-variable warnings.
219    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
220        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
221        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
222        also returns the mark "x". This bug applied to capturing parentheses,
223        non-capturing parentheses, and atomic parentheses. It also applied to some
224        assertions.
226    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
227        information out of configure.ac instead of relying on pcre.h.generic, which
228        is not stored in the repository.
230    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
231        -lreadline.
233    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
235    15. Applied Graycode's patch to put the top-level frame on the stack rather
236        than the heap when not using the stack for recursion. This gives a
237        performance improvement in many cases when recursion is not deep.
239    16. Experimental code added to "pcretest -C" to output the stack frame size.
242    Version 8.21 12-Dec-2011
243    ------------------------
245    1.  Updating the JIT compiler.
247    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
248        are added as well.
250    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
251        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
252        calling _pcre_jit_exec. Some extra comments are added.
254    4.  (*MARK) settings inside atomic groups that do not contain any capturing
255        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
256        was introduced by change 18 for 8.20.
258    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
259        ECMA-262 standard.
261    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
262        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
263        This bug was probably introduced by change 9 of 8.13.
265    7.  While fixing 6 above, I noticed that a number of other items were being
266        incorrectly rejected as "not fixed length". This arose partly because newer
267        opcodes had not been added to the fixed-length checking code. I have (a)
268        corrected the bug and added tests for these items, and (b) arranged for an
269        error to occur if an unknown opcode is encountered while checking for fixed
270        length instead of just assuming "not fixed length". The items that were
271        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
272        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
273        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
275    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
276        being incorrectly compiled and would have given unpredicatble results.
278    9.  A possessively repeated subpattern with minimum repeat count greater than
279        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
280        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
281        the first (A) could occur when it should not.
283    10. Add a cast and remove a redundant test from the code.
285    11. JIT should use pcre_malloc/pcre_free for allocation.
287    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
288        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
289        is anything other than /usr, -L is still shown).
291    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
293    14. Perl does not support \N without a following name in a [] class; PCRE now
294        also gives an error.
296    15. If a forward reference was repeated with an upper limit of around 2000,
297        it caused the error "internal error: overran compiling workspace". The
298        maximum number of forward references (including repeats) was limited by the
299        internal workspace, and dependent on the LINK_SIZE. The code has been
300        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
301        the default depends on LINK_SIZE. There is a new upper limit (for safety)
302        of around 200,000 forward references. While doing this, I also speeded up
303        the filling in of repeated forward references.
305    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
306        incorrectly expecting the subject to contain another "a" after the start.
308    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
309        in the match, the SKIP should be ignored. This was not happening; instead
310        the SKIP was being treated as NOMATCH. For patterns such as
311        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
312        tested.
314    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
315        now much more compatible with Perl, in particular in cases where the result
316        is a non-match for a non-anchored pattern. For example, if
317        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
318        "m", where previously it did not return a name. A side effect of this
319        change is that for partial matches, the last encountered mark name is
320        returned, as for non matches. A number of tests that were previously not
321        Perl-compatible have been moved into the Perl-compatible test files. The
322        refactoring has had the pleasing side effect of removing one argument from
323        the match() function, thus reducing its stack requirements.
325    19. If the /S+ option was used in pcretest to study a pattern using JIT,
326        subsequent uses of /S (without +) incorrectly behaved like /S+.
328    21. Retrieve executable code size support for the JIT compiler and fixing
329        some warnings.
331    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
332        not work when the shorter character appeared right at the end of the
333        subject string.
335    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
336        systems.
338    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
339        output it when the /M option is used in pcretest.
341    25. The CheckMan script was not being included in the distribution. Also, added
342        an explicit "perl" to run Perl scripts from the PrepareRelease script
343        because this is reportedly needed in Windows.
345    26. If study data was being save in a file and studying had not found a set of
346        "starts with" bytes for the pattern, the data written to the file (though
347        never used) was taken from uninitialized memory and so caused valgrind to
348        complain.
350    27. Updated RunTest.bat as provided by Sheri Pierce.
352    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
354    29. Computation of memory usage for the table of capturing group names was
355        giving an unnecessarily large value.
358    Version 8.20 21-Oct-2011
359    ------------------------
361    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
362        a POSIX class. After further experiments with Perl, which convinced me that
363        Perl has bugs and confusions, a closing square bracket is no longer allowed
364        in a POSIX name. This bug also affected patterns with classes that started
365        with full stops.
367    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
368        captured substring, but while checking the failing first alternative,
369        substring 1 is temporarily captured. If the output vector supplied to
370        pcre_exec() was not big enough for this capture, the yield of the function
371        was still zero ("insufficient space for captured substrings"). This cannot
372        be totally fixed without adding another stack variable, which seems a lot
373        of expense for a edge case. However, I have improved the situation in cases
374        such as /(a)(b)x|abc/ matched against "abc", where the return code
375        indicates that fewer than the maximum number of slots in the ovector have
376        been set.
378    3.  Related to (2) above: when there are more back references in a pattern than
379        slots in the output vector, pcre_exec() uses temporary memory during
380        matching, and copies in the captures as far as possible afterwards. It was
381        using the entire output vector, but this conflicts with the specification
382        that only 2/3 is used for passing back captured substrings. Now it uses
383        only the first 2/3, for compatibility. This is, of course, another edge
384        case.
386    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
387        main code base, and can be used by building with --enable-jit. When this is
388        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
389        runtime --no-jit option is given.
391    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
392        ovector, the return from the function was zero, implying that there were
393        other matches that did not fit. The correct "exactly full" value is now
394        returned.
396    6.  If a subpattern that was called recursively or as a subroutine contained
397        (*PRUNE) or any other control that caused it to give a non-standard return,
398        invalid errors such as "Error -26 (nested recursion at the same subject
399        position)" or even infinite loops could occur.
401    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
402        computing the minimum length on reaching *ACCEPT, and so ended up with the
403        wrong value of 1 rather than 0. Further investigation indicates that
404        computing a minimum subject length in the presence of *ACCEPT is difficult
405        (think back references, subroutine calls), and so I have changed the code
406        so that no minimum is registered for a pattern that contains *ACCEPT.
408    8.  If (*THEN) was present in the first (true) branch of a conditional group,
409        it was not handled as intended. [But see 16 below.]
411    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
412        Sheri Pierce.
414    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
415        the first byte in a match must be "a".
417    11. Change 17 for 8.13 increased the recursion depth for patterns like
418        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
419        pattern contains any instances of (*THEN). If it does not, the old
420        optimizations are restored. It would be nice to do this on a per-group
421        basis, but at the moment that is not feasible.
423    12. In some environments, the output of pcretest -C is CRLF terminated. This
424        broke RunTest's code that checks for the link size. A single white space
425        character after the value is now allowed for.
427    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
428        For "fr", it uses the Windows-specific input and output files.
430    14. If (*THEN) appeared in a group that was called recursively or as a
431        subroutine, it did not work as intended. [But see next item.]
433    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
434        pattern fragments (but not containing any | characters). If A and B are
435        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
436        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
437        D. In other words, Perl considers parentheses that do not contain any |
438        characters to be part of a surrounding alternative, whereas PCRE was
439        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
440        differently. PCRE now behaves in the same way as Perl, except in the case
441        of subroutine/recursion calls such as (?1) which have in any case always
442        been different (but PCRE had them first :-).
444    16. Related to 15 above: Perl does not treat the | in a conditional group as
445        creating alternatives. Such a group is treated in the same way as an
446        ordinary group without any | characters when processing (*THEN). PCRE has
447        been changed to match Perl's behaviour.
449    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
450        RunGrepTest script failed.
452    18. Change 22 for version 13 caused atomic groups to use more stack. This is
453        inevitable for groups that contain captures, but it can lead to a lot of
454        stack use in large patterns. The old behaviour has been restored for atomic
455        groups that do not contain any capturing parentheses.
457    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
458        suppress the check for a minimum subject length at run time. (If it was
459        given to pcre_exec() or pcre_dfa_exec() it did work.)
461    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
462        fail to work when decoding hex characters in data strings in EBCDIC
463        environments.
465    21. It appears that in at least one Mac OS environment, the isxdigit() function
466        is implemented as a macro that evaluates to its argument more than once,
467        contravening the C 90 Standard (I haven't checked a later standard). There
468        was an instance in pcretest which caused it to go wrong when processing
469        \x{...} escapes in subject strings. The has been rewritten to avoid using
470        things like p++ in the argument of isxdigit().
473    Version 8.13 16-Aug-2011
474    ------------------------
476    1.  The Unicode data tables have been updated to Unicode 6.0.0.
478    2.  Two minor typos in pcre_internal.h have been fixed.
480    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
481        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
482        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
484    4.  There were a number of related bugs in the code for matching backrefences
485        caselessly in UTF-8 mode when codes for the characters concerned were
486        different numbers of bytes. For example, U+023A and U+2C65 are an upper
487        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
488        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
489        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
490        2-byte code at the end of the subject (it thought there wasn't enough data
491        left).
493    5.  Comprehensive information about what went wrong is now returned by
494        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
495        as the output vector has at least 2 elements. The offset of the start of
496        the failing character and a reason code are placed in the vector.
498    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
499        now returned is for the first byte of the failing character, instead of the
500        last byte inspected. This is an incompatible change, but I hope it is small
501        enough not to be a problem. It makes the returned offset consistent with
502        pcre_exec() and pcre_dfa_exec().
504    7.  pcretest now gives a text phrase as well as the error number when
505        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
506        failure, the offset and reason code are output.
508    8.  When \R was used with a maximizing quantifier it failed to skip backwards
509        over a \r\n pair if the subsequent match failed. Instead, it just skipped
510        back over a single character (\n). This seems wrong (because it treated the
511        two characters as a single entity when going forwards), conflicts with the
512        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
513        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
514        has been changed.
516    9.  Some internal refactoring has changed the processing so that the handling
517        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
518        time (the PCRE_DOTALL option was changed this way some time ago: version
519        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
520        which was always a bit of a fudge. It also means that there is one less
521        argument for the match() function, which reduces its stack requirements
522        slightly. This change also fixes an incompatibility with Perl: the pattern
523        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
525    10. More internal refactoring has drastically reduced the number of recursive
526        calls to match() for possessively repeated groups such as (abc)++ when
527        using pcre_exec().
529    11. While implementing 10, a number of bugs in the handling of groups were
530        discovered and fixed:
532        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
533        (a|)*(?1) gave a compile-time internal error.
534        ((a|)+)+  did not notice that the outer group could match an empty string.
535        (^a|^)+   was not marked as anchored.
536        (.*a|.*)+ was not marked as matching at start or after a newline.
538    12. Yet more internal refactoring has removed another argument from the match()
539        function. Special calls to this function are now indicated by setting a
540        value in a variable in the "match data" data block.
542    13. Be more explicit in pcre_study() instead of relying on "default" for
543        opcodes that mean there is no starting character; this means that when new
544        ones are added and accidentally left out of pcre_study(), testing should
545        pick them up.
547    14. The -s option of pcretest has been documented for ages as being an old
548        synonym of -m (show memory usage). I have changed it to mean "force study
549        for every regex", that is, assume /S for every regex. This is similar to -i
550        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
551        using it. It makes it easier to run collections of tests with and without
552        study enabled, and thereby test pcre_study() more easily. All the standard
553        tests are now run with and without -s (but some patterns can be marked as
554        "never study" - see 20 below).
556    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
557        restoration of the capturing data to the outer values was not happening
558        correctly.
560    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
561        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
562        pattern had matched an empty string, and so incorrectly returned a no
563        match.
565    17. There was optimizing code for the last branch of non-capturing parentheses,
566        and also for the obeyed branch of a conditional subexpression, which used
567        tail recursion to cut down on stack usage. Unfortunately, now that there is
568        the possibility of (*THEN) occurring in these branches, tail recursion is
569        no longer possible because the return has to be checked for (*THEN). These
570        two optimizations have therefore been removed. [But see 8.20/11 above.]
572    18. If a pattern containing \R was studied, it was assumed that \R always
573        matched two bytes, thus causing the minimum subject length to be
574        incorrectly computed because \R can also match just one byte.
576    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
577        was incorrectly computed.
579    20. If /S is present twice on a test pattern in pcretest input, it now
580        *disables* studying, thereby overriding the use of -s on the command line
581        (see 14 above). This is necessary for one or two tests to keep the output
582        identical in both cases.
584    21. When (*ACCEPT) was used in an assertion that matched an empty string and
585        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
587    22. When an atomic group that contained a capturing parenthesis was
588        successfully matched, but the branch in which it appeared failed, the
589        capturing was not being forgotten if a higher numbered group was later
590        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
591        group 1 to "a", when in fact it should be unset. This applied to multi-
592        branched capturing and non-capturing groups, repeated or not, and also to
593        positive assertions (capturing in negative assertions does not happen
594        in PCRE) and also to nested atomic groups.
596    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
597        subject after a captured substring, to make it easier to tell which of a
598        number of identical substrings has been captured.
600    24. The way atomic groups are processed by pcre_exec() has been changed so that
601        if they are repeated, backtracking one repetition now resets captured
602        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
603        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
604        "aaa". Previously, it would have been "a". As part of this code
605        refactoring, the way recursive calls are handled has also been changed.
607    25. If an assertion condition captured any substrings, they were not passed
608        back unless some other capturing happened later. For example, if
609        (?(?=(a))a) was matched against "a", no capturing was returned.
611    26. When studying a pattern that contained subroutine calls or assertions,
612        the code for finding the minimum length of a possible match was handling
613        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
614        group 1 called group 2 while simultaneously a separate group 2 called group
615        1). A stack overflow occurred in this case. I have fixed this by limiting
616        the recursion depth to 10.
618    27. Updated RunTest.bat in the distribution to the version supplied by Tom
619        Fortmann. This supports explicit test numbers on the command line, and has
620        argument validation and error reporting.
622    28. An instance of \X with an unlimited repeat could fail if at any point the
623        first character it looked at was a mark character.
625    29. Some minor code refactoring concerning Unicode properties and scripts
626        should reduce the stack requirement of match() slightly.
628    30. Added the '=' option to pcretest to check the setting of unused capturing
629        slots at the end of the pattern, which are documented as being -1, but are
630        not included in the return count.
632    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
633        compiled something random. Now it gives a compile-time error (as does
634        Perl).
636    32. A *MARK encountered during the processing of a positive assertion is now
637        recorded and passed back (compatible with Perl).
639    33. If --only-matching or --colour was set on a pcregrep call whose pattern
640        had alternative anchored branches, the search for a second match in a line
641        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
642        matched the line "0102" twice. The same bug affected patterns that started
643        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
644        twice.
646    34. Previously, PCRE did not allow quantification of assertions. However, Perl
647        does, and because of capturing effects, quantifying parenthesized
648        assertions may at times be useful. Quantifiers are now allowed for
649        parenthesized assertions.
651    35. A minor code tidy in pcre_compile() when checking options for \R usage.
653    36. \g was being checked for fancy things in a character class, when it should
654        just be a literal "g".
656    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
657        appearance of a nested POSIX class supersedes an apparent external class.
658        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
659        unescaped square brackets may also appear as part of class names. For
660        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
661        more like Perl. (But see 8.20/1 above.)
663    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
664        was because it thought it was \N{name}, which is not supported).
666    39. Add minix to OS list not supporting the -S option in pcretest.
668    40. PCRE tries to detect cases of infinite recursion at compile time, but it
669        cannot analyze patterns in sufficient detail to catch mutual recursions
670        such as ((?1))((?2)). There is now a runtime test that gives an error if a
671        subgroup is called recursively as a subpattern for a second time at the
672        same position in the subject string. In previous releases this might have
673        been caught by the recursion limit, or it might have run out of stack.
675    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
676        happen only once. PCRE was, however incorrectly giving a compile time error
677        "recursive call could loop indefinitely" because it cannot analyze the
678        pattern in sufficient detail. The compile time test no longer happens when
679        PCRE is compiling a conditional subpattern, but actual runaway loops are
680        now caught at runtime (see 40 above).
682    42. It seems that Perl allows any characters other than a closing parenthesis
683        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
684        has been changed to be the same.
686    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
687        as not to get warnings when autogen.sh is called. Also changed
688        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
690    44. To help people who use pcregrep to scan files containing exceedingly long
691        lines, the following changes have been made:
693        (a) The default value of the buffer size parameter has been increased from
694            8K to 20K. (The actual buffer used is three times this size.)
696        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
697            PCRE is built.
699        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
700            to be set at run time.
702        (d) Numerical values in pcregrep options can be followed by K or M, for
703            example --buffer-size=50K.
705        (e) If a line being scanned overflows pcregrep's buffer, an error is now
706            given and the return code is set to 2.
708    45. Add a pointer to the latest mark to the callout data block.
710    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
711        partial match of an empty string instead of no match. This was specific to
712        the use of ".".
714    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
715        complete match instead of a partial match. This bug was dependent on both
716        the PCRE_UTF8 and PCRE_DOTALL options being set.
718    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
719        starting byte set, because \b was not being ignored.
722    Version 8.12 15-Jan-2011
723    ------------------------
725    1.  Fixed some typos in the markup of the man pages, and wrote a script that
726        checks for such things as part of the documentation building process.
728    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
729        --match-limit and --recursion-limit options (added for 8.11). In
730        particular, this made one of the standard tests fail. (The integer value
731        went into the wrong half of a long int.)
733    3.  If the --colour option was given to pcregrep with -v (invert match), it
734        did strange things, either producing crazy output, or crashing. It should,
735        of course, ignore a request for colour when reporting lines that do not
736        match.
738    4.  Another pcregrep bug caused similar problems if --colour was specified with
739        -M (multiline) and the pattern match finished with a line ending.
741    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
742        matched in multiline mode, the following line was shown as part of the
743        match. This seems wrong, so I have changed it.
745    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
746        the check for further matches in the same line (so they could be coloured)
747        to overrun the end of the current line. If another match was found, it was
748        incorrectly shown (and then shown again when found in the next line).
750    7.  If pcregrep was compiled under Windows, there was a reference to the
751        function pcregrep_exit() before it was defined. I am assuming this was
752        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
753        reported by a user. I've moved the definition above the reference.
756    Version 8.11 10-Dec-2010
757    ------------------------
759    1.  (*THEN) was not working properly if there were untried alternatives prior
760        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
761        backtracked to try for "b" instead of moving to the next alternative branch
762        at the same level (in this case, to look for "c"). The Perl documentation
763        is clear that when (*THEN) is backtracked onto, it goes to the "next
764        alternative in the innermost enclosing group".
766    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
767        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
768        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
769        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
770        (*THEN).
772    3.  If \s appeared in a character class, it removed the VT character from
773        the class, even if it had been included by some previous item, for example
774        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
775        of \s, but is part of the POSIX "space" class.)
777    4.  A partial match never returns an empty string (because you can always
778        match an empty string at the end of the subject); however the checking for
779        an empty string was starting at the "start of match" point. This has been
780        changed to the "earliest inspected character" point, because the returned
781        data for a partial match starts at this character. This means that, for
782        example, /(?<=abc)def/ gives a partial match for the subject "abc"
783        (previously it gave "no match").
785    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
786        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
787        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
788        has an implication that the given string is incomplete (because a partial
789        match is preferred over a full match). For this reason, these items now
790        give a partial match in this situation. [Aside: previously, the one case
791        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
792        match rather than a full match, which was wrong by the old rules, but is
793        now correct.]
795    6.  There was a bug in the handling of #-introduced comments, recognized when
796        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
797        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
798        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
799        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
800        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
801        places in pcre_compile().
803    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
804        comments when looking ahead for named forward references to subpatterns,
805        the only newline sequence it recognized was NL. It now handles newlines
806        according to the set newline convention.
808    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
809        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
810        cater for a lack of strerror(). These oversights have been fixed.
812    9.  Added --match-limit and --recursion-limit to pcregrep.
814    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
816    11. When the -o option was used, pcregrep was setting a return code of 1, even
817        when matches were found, and --line-buffered was not being honoured.
819    12. Added an optional parentheses number to the -o and --only-matching options
820        of pcregrep.
822    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
823        can match an empty string. The code to do it in pcretest and pcredemo
824        needed fixing:
826        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
827            only one byte after an empty string match just before CRLF (this case
828            just got forgotten; "any" and "anycrlf" were OK).
830        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
831            mode when an empty string match preceded an ASCII character followed by
832            a non-ASCII character. (The code for advancing by one character rather
833            than one byte was nonsense.)
835        (c) The pcredemo.c sample program did not have any code at all to handle
836            the cases when CRLF is a valid newline sequence.
838    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
839        as a starting offset was within the subject string. There is now a new
840        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
841        negative or greater than the length of the string. In order to test this,
842        pcretest is extended to allow the setting of negative starting offsets.
844    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
845        starting offset points to the beginning of a UTF-8 character was
846        unnecessarily clumsy. I tidied it up.
848    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
849        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
851    17. Nobody had reported that the --include_dir option, which was added in
852        release 7.7 should have been called --include-dir (hyphen, not underscore)
853        for compatibility with GNU grep. I have changed it to --include-dir, but
854        left --include_dir as an undocumented synonym, and the same for
855        --exclude-dir, though that is not available in GNU grep, at least as of
856        release 2.5.4.
858    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
859        characters from a string of bytes) have been redefined so as not to use
860        loops, in order to improve performance in some environments. At the same
861        time, I abstracted some of the common code into auxiliary macros to save
862        repetition (this should not affect the compiled code).
864    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
865        compile-time error is now given if \c is not followed by an ASCII
866        character, that is, a byte less than 128. (In EBCDIC mode, the code is
867        different, and any byte value is allowed.)
869    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
870        START_OPTIMIZE option, which is now allowed at compile time - but just
871        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
872        to pcregrep and other applications that have no direct access to PCRE
873        options. The new /Y option in pcretest sets this option when calling
874        pcre_compile().
876    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
877        back references. Groups containing recursive back references were forced to
878        be atomic by that change, but in the case of named groups, the amount of
879        memory required was incorrectly computed, leading to "Failed: internal
880        error: code overflow". This has been fixed.
882    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
883        pcretest.c, to avoid build problems in some Borland environments.
886    Version 8.10 25-Jun-2010
887  ------------------------  ------------------------
889  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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