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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.15 12-Jan-2011  Version 8.31 06-July-2012
5    -------------------------
6    
7    1.  Fixing a wrong JIT test case and some compiler warnings.
8    
9    2.  Removed a bashism from the RunTest script.
10    
11    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
12        to unsigned type, result still unsigned" that was given by an MS compiler
13        on encountering the code "-sizeof(xxx)".
14    
15    4.  Partial matching support is added to the JIT compiler.
16    
17    5.  Fixed several bugs concerned with partial matching of items that consist
18        of more than one character:
19    
20        (a) /^(..)\1/ did not partially match "aba" because checking references was
21            done on an "all or nothing" basis. This also applied to repeated
22            references.
23    
24        (b) \R did not give a hard partial match if \r was found at the end of the
25            subject.
26    
27        (c) \X did not give a hard partial match after matching one or more
28            characters at the end of the subject.
29    
30        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
31            a partial match for the string "\r".
32    
33        (e) When newline was set to CRLF, the metacharacter "." did not recognize
34            a partial match for a CR character at the end of the subject string.
35    
36    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
37        running pcretest, the text "(JIT)" added to the output whenever JIT is
38        actually used to run the match.
39    
40    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
41        or /S+[+] with a digit between 1 and 7.
42    
43    8.  OP_NOT now supports any UTF character not just single-byte ones.
44    
45    9.  (*MARK) control verb is now supported by the JIT compiler.
46    
47    10. The command "./RunTest list" lists the available tests without actually
48        running any of them. (Because I keep forgetting what they all are.)
49    
50    11. Add PCRE_INFO_MAXLOOKBEHIND.
51    
52    12. Applied a (slightly modified) user-supplied patch that improves performance
53        when the heap is used for recursion (compiled with --disable-stack-for-
54        recursion). Instead of malloc and free for each heap frame each time a
55        logical recursion happens, frames are retained on a chain and re-used where
56        possible. This sometimes gives as much as 30% improvement.
57    
58    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
59        call.
60    
61    14. As documented, (*COMMIT) is now confined to within a positive assertion.
62    
63    15. It is now possible to link pcretest with libedit as an alternative to
64        libreadline.
65    
66    16. (*COMMIT) control verb is now supported by the JIT compiler.
67    
68    17. The Unicode data tables have been updated to Unicode 6.1.0.
69    
70    18. Added --file-list option to pcregrep.
71    
72    19. Added binary file support to pcregrep, including the -a, --binary-files,
73        -I, and --text options.
74    
75    20. The madvise function is renamed for posix_madvise for QNX compatibility
76        reasons. Fixed by Giuseppe D'Angelo.
77    
78    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
79    
80    22. Changed the option for creating symbolic links for 16-bit man pages from
81        -s to -sf so that re-installing does not cause issues.
82    
83    23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.
84    
85    24. Fixed a very old bug in pcretest that caused errors with restarted DFA
86        matches in certain environments (the workspace was not being correctly
87        retained). Also added to pcre_dfa_exec() a simple plausibility check on
88        some of the workspace data at the beginning of a restart.
89    
90    25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
91        was not doing so when it should - probably a typo introduced by SVN 528
92        (change 8.10/14).
93    
94    26. When PCRE_UCP was not set, \w+\x{c4} was incorrectly auto-possessifying the
95        \w+ when the character tables indicated that \x{c4} was a word character.
96        There were several related cases, all because the tests for doing a table
97        lookup were testing for characters less than 127 instead of 255.
98    
99    27. If a pattern contains capturing parentheses that are not used in a match,
100        their slots in the ovector are set to -1. For those that are higher than
101        any matched groups, this happens at the end of processing. In the case when
102        there were back references that the ovector was too small to contain
103        (causing temporary malloc'd memory to be used during matching), and the
104        highest capturing number was not used, memory off the end of the ovector
105        was incorrectly being set to -1. (It was using the size of the temporary
106        memory instead of the true size.)
107    
108    28. To catch bugs like 27 using valgrind, when pcretest is asked to specify an
109        ovector size, it uses memory at the end of the block that it has got.
110    
111    29. Check for an overlong MARK name and give an error at compile time. The
112        limit is 255 for the 8-bit library and 65535 for the 16-bit library.
113    
114    30. JIT compiler update.
115    
116    31. JIT is now supported on jailbroken iOS devices. Thanks for Ruiger
117        Rill for the patch.
118    
119    32. Put spaces around SLJIT_PRINT_D in the JIT compiler. Required by CXX11.
120    
121    33. Variable renamings in the PCRE-JIT compiler. No functionality change.
122    
123    34. Fixed typos in pcregrep: in two places there was SUPPORT_LIBZ2 instead of
124        SUPPORT_LIBBZ2. This caused a build problem when bzip2 but not gzip (zlib)
125        was enabled.
126    
127    35. Improve JIT code generation for greedy plus quantifier.
128    
129    36. When /((?:a?)*)*c/ or /((?>a?)*)*c/ was matched against "aac", it set group
130        1 to "aa" instead of to an empty string. The bug affected repeated groups
131        that could potentially match an empty string.
132    
133    37. Optimizing single character iterators in JIT.
134    
135    38. Wide characters specified with \uxxxx in JavaScript mode are now subject to
136        the same checks as \x{...} characters in non-JavaScript mode. Specifically,
137        codepoints that are too big for the mode are faulted, and in a UTF mode,
138        disallowed codepoints are also faulted.
139    
140    39. If PCRE was compiled with UTF support, in three places in the DFA
141        matcher there was code that should only have been obeyed in UTF mode, but
142        was being obeyed unconditionally. In 8-bit mode this could cause incorrect
143        processing when bytes with values greater than 127 were present. In 16-bit
144        mode the bug would be provoked by values in the range 0xfc00 to 0xdc00. In
145        both cases the values are those that cannot be the first data item in a UTF
146        character. The three items that might have provoked this were recursions,
147        possessively repeated groups, and atomic groups.
148    
149    40. Ensure that libpcre is explicitly listed in the link commands for pcretest
150        and pcregrep, because some OS require shared objects to be explicitly
151        passed to ld, causing the link step to fail if they are not.
152    
153    41. There were two incorrect #ifdefs in pcre_study.c, meaning that, in 16-bit
154        mode, patterns that started with \h* or \R* might be incorrectly matched.
155    
156    
157    Version 8.30 04-February-2012
158    -----------------------------
159    
160    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
161        name is defined in ctype.h.
162    
163    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
164        only in quite long subpatterns.
165    
166    3.  Removed the function pcre_info(), which has been obsolete and deprecated
167        since it was replaced by pcre_fullinfo() in February 2000.
168    
169    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
170        match a (*MARK), and the match failed at the start of the subject, a
171        reference to memory before the start of the subject could occur. This bug
172        was introduced by fix 17 of release 8.21.
173    
174    5.  A reference to an unset group with zero minimum repetition was giving
175        totally wrong answers (in non-JavaScript-compatibility mode). For example,
176        /(another)?(\1?)test/ matched against "hello world test". This bug was
177        introduced in release 8.13.
178    
179    6.  Add support for 16-bit character strings (a large amount of work involving
180        many changes and refactorings).
181    
182    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
183        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
184        from a file.
185    
186    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
187        rounding is not applied in this particular case).
188    
189    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
190        if they appear, or are escaped, in patterns.
191    
192    10. Get rid of a number of -Wunused-but-set-variable warnings.
193    
194    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
195        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
196        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
197        also returns the mark "x". This bug applied to capturing parentheses,
198        non-capturing parentheses, and atomic parentheses. It also applied to some
199        assertions.
200    
201    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
202        information out of configure.ac instead of relying on pcre.h.generic, which
203        is not stored in the repository.
204    
205    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
206        -lreadline.
207    
208    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
209    
210    15. Applied Graycode's patch to put the top-level frame on the stack rather
211        than the heap when not using the stack for recursion. This gives a
212        performance improvement in many cases when recursion is not deep.
213    
214    16. Experimental code added to "pcretest -C" to output the stack frame size.
215    
216    
217    Version 8.21 12-Dec-2011
218    ------------------------
219    
220    1.  Updating the JIT compiler.
221    
222    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
223        are added as well.
224    
225    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
226        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
227        calling _pcre_jit_exec. Some extra comments are added.
228    
229    4.  (*MARK) settings inside atomic groups that do not contain any capturing
230        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
231        was introduced by change 18 for 8.20.
232    
233    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
234        ECMA-262 standard.
235    
236    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
237        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
238        This bug was probably introduced by change 9 of 8.13.
239    
240    7.  While fixing 6 above, I noticed that a number of other items were being
241        incorrectly rejected as "not fixed length". This arose partly because newer
242        opcodes had not been added to the fixed-length checking code. I have (a)
243        corrected the bug and added tests for these items, and (b) arranged for an
244        error to occur if an unknown opcode is encountered while checking for fixed
245        length instead of just assuming "not fixed length". The items that were
246        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
247        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
248        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
249    
250    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
251        being incorrectly compiled and would have given unpredicatble results.
252    
253    9.  A possessively repeated subpattern with minimum repeat count greater than
254        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
255        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
256        the first (A) could occur when it should not.
257    
258    10. Add a cast and remove a redundant test from the code.
259    
260    11. JIT should use pcre_malloc/pcre_free for allocation.
261    
262    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
263        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
264        is anything other than /usr, -L is still shown).
265    
266    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
267    
268    14. Perl does not support \N without a following name in a [] class; PCRE now
269        also gives an error.
270    
271    15. If a forward reference was repeated with an upper limit of around 2000,
272        it caused the error "internal error: overran compiling workspace". The
273        maximum number of forward references (including repeats) was limited by the
274        internal workspace, and dependent on the LINK_SIZE. The code has been
275        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
276        the default depends on LINK_SIZE. There is a new upper limit (for safety)
277        of around 200,000 forward references. While doing this, I also speeded up
278        the filling in of repeated forward references.
279    
280    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
281        incorrectly expecting the subject to contain another "a" after the start.
282    
283    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
284        in the match, the SKIP should be ignored. This was not happening; instead
285        the SKIP was being treated as NOMATCH. For patterns such as
286        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
287        tested.
288    
289    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
290        now much more compatible with Perl, in particular in cases where the result
291        is a non-match for a non-anchored pattern. For example, if
292        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
293        "m", where previously it did not return a name. A side effect of this
294        change is that for partial matches, the last encountered mark name is
295        returned, as for non matches. A number of tests that were previously not
296        Perl-compatible have been moved into the Perl-compatible test files. The
297        refactoring has had the pleasing side effect of removing one argument from
298        the match() function, thus reducing its stack requirements.
299    
300    19. If the /S+ option was used in pcretest to study a pattern using JIT,
301        subsequent uses of /S (without +) incorrectly behaved like /S+.
302    
303    21. Retrieve executable code size support for the JIT compiler and fixing
304        some warnings.
305    
306    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
307        not work when the shorter character appeared right at the end of the
308        subject string.
309    
310    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
311        systems.
312    
313    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
314        output it when the /M option is used in pcretest.
315    
316    25. The CheckMan script was not being included in the distribution. Also, added
317        an explicit "perl" to run Perl scripts from the PrepareRelease script
318        because this is reportedly needed in Windows.
319    
320    26. If study data was being save in a file and studying had not found a set of
321        "starts with" bytes for the pattern, the data written to the file (though
322        never used) was taken from uninitialized memory and so caused valgrind to
323        complain.
324    
325    27. Updated RunTest.bat as provided by Sheri Pierce.
326    
327    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
328    
329    29. Computation of memory usage for the table of capturing group names was
330        giving an unnecessarily large value.
331    
332    
333    Version 8.20 21-Oct-2011
334    ------------------------
335    
336    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
337        a POSIX class. After further experiments with Perl, which convinced me that
338        Perl has bugs and confusions, a closing square bracket is no longer allowed
339        in a POSIX name. This bug also affected patterns with classes that started
340        with full stops.
341    
342    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
343        captured substring, but while checking the failing first alternative,
344        substring 1 is temporarily captured. If the output vector supplied to
345        pcre_exec() was not big enough for this capture, the yield of the function
346        was still zero ("insufficient space for captured substrings"). This cannot
347        be totally fixed without adding another stack variable, which seems a lot
348        of expense for a edge case. However, I have improved the situation in cases
349        such as /(a)(b)x|abc/ matched against "abc", where the return code
350        indicates that fewer than the maximum number of slots in the ovector have
351        been set.
352    
353    3.  Related to (2) above: when there are more back references in a pattern than
354        slots in the output vector, pcre_exec() uses temporary memory during
355        matching, and copies in the captures as far as possible afterwards. It was
356        using the entire output vector, but this conflicts with the specification
357        that only 2/3 is used for passing back captured substrings. Now it uses
358        only the first 2/3, for compatibility. This is, of course, another edge
359        case.
360    
361    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
362        main code base, and can be used by building with --enable-jit. When this is
363        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
364        runtime --no-jit option is given.
365    
366    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
367        ovector, the return from the function was zero, implying that there were
368        other matches that did not fit. The correct "exactly full" value is now
369        returned.
370    
371    6.  If a subpattern that was called recursively or as a subroutine contained
372        (*PRUNE) or any other control that caused it to give a non-standard return,
373        invalid errors such as "Error -26 (nested recursion at the same subject
374        position)" or even infinite loops could occur.
375    
376    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
377        computing the minimum length on reaching *ACCEPT, and so ended up with the
378        wrong value of 1 rather than 0. Further investigation indicates that
379        computing a minimum subject length in the presence of *ACCEPT is difficult
380        (think back references, subroutine calls), and so I have changed the code
381        so that no minimum is registered for a pattern that contains *ACCEPT.
382    
383    8.  If (*THEN) was present in the first (true) branch of a conditional group,
384        it was not handled as intended. [But see 16 below.]
385    
386    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
387        Sheri Pierce.
388    
389    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
390        the first byte in a match must be "a".
391    
392    11. Change 17 for 8.13 increased the recursion depth for patterns like
393        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
394        pattern contains any instances of (*THEN). If it does not, the old
395        optimizations are restored. It would be nice to do this on a per-group
396        basis, but at the moment that is not feasible.
397    
398    12. In some environments, the output of pcretest -C is CRLF terminated. This
399        broke RunTest's code that checks for the link size. A single white space
400        character after the value is now allowed for.
401    
402    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
403        For "fr", it uses the Windows-specific input and output files.
404    
405    14. If (*THEN) appeared in a group that was called recursively or as a
406        subroutine, it did not work as intended. [But see next item.]
407    
408    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
409        pattern fragments (but not containing any | characters). If A and B are
410        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
411        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
412        D. In other words, Perl considers parentheses that do not contain any |
413        characters to be part of a surrounding alternative, whereas PCRE was
414        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
415        differently. PCRE now behaves in the same way as Perl, except in the case
416        of subroutine/recursion calls such as (?1) which have in any case always
417        been different (but PCRE had them first :-).
418    
419    16. Related to 15 above: Perl does not treat the | in a conditional group as
420        creating alternatives. Such a group is treated in the same way as an
421        ordinary group without any | characters when processing (*THEN). PCRE has
422        been changed to match Perl's behaviour.
423    
424    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
425        RunGrepTest script failed.
426    
427    18. Change 22 for version 13 caused atomic groups to use more stack. This is
428        inevitable for groups that contain captures, but it can lead to a lot of
429        stack use in large patterns. The old behaviour has been restored for atomic
430        groups that do not contain any capturing parentheses.
431    
432    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
433        suppress the check for a minimum subject length at run time. (If it was
434        given to pcre_exec() or pcre_dfa_exec() it did work.)
435    
436    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
437        fail to work when decoding hex characters in data strings in EBCDIC
438        environments.
439    
440    21. It appears that in at least one Mac OS environment, the isxdigit() function
441        is implemented as a macro that evaluates to its argument more than once,
442        contravening the C 90 Standard (I haven't checked a later standard). There
443        was an instance in pcretest which caused it to go wrong when processing
444        \x{...} escapes in subject strings. The has been rewritten to avoid using
445        things like p++ in the argument of isxdigit().
446    
447    
448    Version 8.13 16-Aug-2011
449    ------------------------
450    
451    1.  The Unicode data tables have been updated to Unicode 6.0.0.
452    
453    2.  Two minor typos in pcre_internal.h have been fixed.
454    
455    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
456        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
457        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
458    
459    4.  There were a number of related bugs in the code for matching backrefences
460        caselessly in UTF-8 mode when codes for the characters concerned were
461        different numbers of bytes. For example, U+023A and U+2C65 are an upper
462        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
463        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
464        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
465        2-byte code at the end of the subject (it thought there wasn't enough data
466        left).
467    
468    5.  Comprehensive information about what went wrong is now returned by
469        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
470        as the output vector has at least 2 elements. The offset of the start of
471        the failing character and a reason code are placed in the vector.
472    
473    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
474        now returned is for the first byte of the failing character, instead of the
475        last byte inspected. This is an incompatible change, but I hope it is small
476        enough not to be a problem. It makes the returned offset consistent with
477        pcre_exec() and pcre_dfa_exec().
478    
479    7.  pcretest now gives a text phrase as well as the error number when
480        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
481        failure, the offset and reason code are output.
482    
483    8.  When \R was used with a maximizing quantifier it failed to skip backwards
484        over a \r\n pair if the subsequent match failed. Instead, it just skipped
485        back over a single character (\n). This seems wrong (because it treated the
486        two characters as a single entity when going forwards), conflicts with the
487        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
488        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
489        has been changed.
490    
491    9.  Some internal refactoring has changed the processing so that the handling
492        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
493        time (the PCRE_DOTALL option was changed this way some time ago: version
494        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
495        which was always a bit of a fudge. It also means that there is one less
496        argument for the match() function, which reduces its stack requirements
497        slightly. This change also fixes an incompatibility with Perl: the pattern
498        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
499    
500    10. More internal refactoring has drastically reduced the number of recursive
501        calls to match() for possessively repeated groups such as (abc)++ when
502        using pcre_exec().
503    
504    11. While implementing 10, a number of bugs in the handling of groups were
505        discovered and fixed:
506    
507        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
508        (a|)*(?1) gave a compile-time internal error.
509        ((a|)+)+  did not notice that the outer group could match an empty string.
510        (^a|^)+   was not marked as anchored.
511        (.*a|.*)+ was not marked as matching at start or after a newline.
512    
513    12. Yet more internal refactoring has removed another argument from the match()
514        function. Special calls to this function are now indicated by setting a
515        value in a variable in the "match data" data block.
516    
517    13. Be more explicit in pcre_study() instead of relying on "default" for
518        opcodes that mean there is no starting character; this means that when new
519        ones are added and accidentally left out of pcre_study(), testing should
520        pick them up.
521    
522    14. The -s option of pcretest has been documented for ages as being an old
523        synonym of -m (show memory usage). I have changed it to mean "force study
524        for every regex", that is, assume /S for every regex. This is similar to -i
525        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
526        using it. It makes it easier to run collections of tests with and without
527        study enabled, and thereby test pcre_study() more easily. All the standard
528        tests are now run with and without -s (but some patterns can be marked as
529        "never study" - see 20 below).
530    
531    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
532        restoration of the capturing data to the outer values was not happening
533        correctly.
534    
535    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
536        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
537        pattern had matched an empty string, and so incorrectly returned a no
538        match.
539    
540    17. There was optimizing code for the last branch of non-capturing parentheses,
541        and also for the obeyed branch of a conditional subexpression, which used
542        tail recursion to cut down on stack usage. Unfortunately, now that there is
543        the possibility of (*THEN) occurring in these branches, tail recursion is
544        no longer possible because the return has to be checked for (*THEN). These
545        two optimizations have therefore been removed. [But see 8.20/11 above.]
546    
547    18. If a pattern containing \R was studied, it was assumed that \R always
548        matched two bytes, thus causing the minimum subject length to be
549        incorrectly computed because \R can also match just one byte.
550    
551    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
552        was incorrectly computed.
553    
554    20. If /S is present twice on a test pattern in pcretest input, it now
555        *disables* studying, thereby overriding the use of -s on the command line
556        (see 14 above). This is necessary for one or two tests to keep the output
557        identical in both cases.
558    
559    21. When (*ACCEPT) was used in an assertion that matched an empty string and
560        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
561    
562    22. When an atomic group that contained a capturing parenthesis was
563        successfully matched, but the branch in which it appeared failed, the
564        capturing was not being forgotten if a higher numbered group was later
565        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
566        group 1 to "a", when in fact it should be unset. This applied to multi-
567        branched capturing and non-capturing groups, repeated or not, and also to
568        positive assertions (capturing in negative assertions does not happen
569        in PCRE) and also to nested atomic groups.
570    
571    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
572        subject after a captured substring, to make it easier to tell which of a
573        number of identical substrings has been captured.
574    
575    24. The way atomic groups are processed by pcre_exec() has been changed so that
576        if they are repeated, backtracking one repetition now resets captured
577        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
578        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
579        "aaa". Previously, it would have been "a". As part of this code
580        refactoring, the way recursive calls are handled has also been changed.
581    
582    25. If an assertion condition captured any substrings, they were not passed
583        back unless some other capturing happened later. For example, if
584        (?(?=(a))a) was matched against "a", no capturing was returned.
585    
586    26. When studying a pattern that contained subroutine calls or assertions,
587        the code for finding the minimum length of a possible match was handling
588        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
589        group 1 called group 2 while simultaneously a separate group 2 called group
590        1). A stack overflow occurred in this case. I have fixed this by limiting
591        the recursion depth to 10.
592    
593    27. Updated RunTest.bat in the distribution to the version supplied by Tom
594        Fortmann. This supports explicit test numbers on the command line, and has
595        argument validation and error reporting.
596    
597    28. An instance of \X with an unlimited repeat could fail if at any point the
598        first character it looked at was a mark character.
599    
600    29. Some minor code refactoring concerning Unicode properties and scripts
601        should reduce the stack requirement of match() slightly.
602    
603    30. Added the '=' option to pcretest to check the setting of unused capturing
604        slots at the end of the pattern, which are documented as being -1, but are
605        not included in the return count.
606    
607    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
608        compiled something random. Now it gives a compile-time error (as does
609        Perl).
610    
611    32. A *MARK encountered during the processing of a positive assertion is now
612        recorded and passed back (compatible with Perl).
613    
614    33. If --only-matching or --colour was set on a pcregrep call whose pattern
615        had alternative anchored branches, the search for a second match in a line
616        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
617        matched the line "0102" twice. The same bug affected patterns that started
618        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
619        twice.
620    
621    34. Previously, PCRE did not allow quantification of assertions. However, Perl
622        does, and because of capturing effects, quantifying parenthesized
623        assertions may at times be useful. Quantifiers are now allowed for
624        parenthesized assertions.
625    
626    35. A minor code tidy in pcre_compile() when checking options for \R usage.
627    
628    36. \g was being checked for fancy things in a character class, when it should
629        just be a literal "g".
630    
631    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
632        appearance of a nested POSIX class supersedes an apparent external class.
633        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
634        unescaped square brackets may also appear as part of class names. For
635        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
636        more like Perl. (But see 8.20/1 above.)
637    
638    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
639        was because it thought it was \N{name}, which is not supported).
640    
641    39. Add minix to OS list not supporting the -S option in pcretest.
642    
643    40. PCRE tries to detect cases of infinite recursion at compile time, but it
644        cannot analyze patterns in sufficient detail to catch mutual recursions
645        such as ((?1))((?2)). There is now a runtime test that gives an error if a
646        subgroup is called recursively as a subpattern for a second time at the
647        same position in the subject string. In previous releases this might have
648        been caught by the recursion limit, or it might have run out of stack.
649    
650    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
651        happen only once. PCRE was, however incorrectly giving a compile time error
652        "recursive call could loop indefinitely" because it cannot analyze the
653        pattern in sufficient detail. The compile time test no longer happens when
654        PCRE is compiling a conditional subpattern, but actual runaway loops are
655        now caught at runtime (see 40 above).
656    
657    42. It seems that Perl allows any characters other than a closing parenthesis
658        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
659        has been changed to be the same.
660    
661    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
662        as not to get warnings when autogen.sh is called. Also changed
663        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
664    
665    44. To help people who use pcregrep to scan files containing exceedingly long
666        lines, the following changes have been made:
667    
668        (a) The default value of the buffer size parameter has been increased from
669            8K to 20K. (The actual buffer used is three times this size.)
670    
671        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
672            PCRE is built.
673    
674        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
675            to be set at run time.
676    
677        (d) Numerical values in pcregrep options can be followed by K or M, for
678            example --buffer-size=50K.
679    
680        (e) If a line being scanned overflows pcregrep's buffer, an error is now
681            given and the return code is set to 2.
682    
683    45. Add a pointer to the latest mark to the callout data block.
684    
685    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
686        partial match of an empty string instead of no match. This was specific to
687        the use of ".".
688    
689    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
690        complete match instead of a partial match. This bug was dependent on both
691        the PCRE_UTF8 and PCRE_DOTALL options being set.
692    
693    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
694        starting byte set, because \b was not being ignored.
695    
696    
697    Version 8.12 15-Jan-2011
698  ------------------------  ------------------------
699    
700  1.  Fixed some typos in the markup of the man pages, and wrote a script that  1.  Fixed some typos in the markup of the man pages, and wrote a script that

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