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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.13 30-Apr-2011  Version 8.32
5    ------------
6    
7    1.  Improved JIT compiler optimizations for first character search and single
8        character iterators.
9    
10    
11    Version 8.31 06-July-2012
12    -------------------------
13    
14    1.  Fixing a wrong JIT test case and some compiler warnings.
15    
16    2.  Removed a bashism from the RunTest script.
17    
18    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
19        to unsigned type, result still unsigned" that was given by an MS compiler
20        on encountering the code "-sizeof(xxx)".
21    
22    4.  Partial matching support is added to the JIT compiler.
23    
24    5.  Fixed several bugs concerned with partial matching of items that consist
25        of more than one character:
26    
27        (a) /^(..)\1/ did not partially match "aba" because checking references was
28            done on an "all or nothing" basis. This also applied to repeated
29            references.
30    
31        (b) \R did not give a hard partial match if \r was found at the end of the
32            subject.
33    
34        (c) \X did not give a hard partial match after matching one or more
35            characters at the end of the subject.
36    
37        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
38            a partial match for the string "\r".
39    
40        (e) When newline was set to CRLF, the metacharacter "." did not recognize
41            a partial match for a CR character at the end of the subject string.
42    
43    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
44        running pcretest, the text "(JIT)" added to the output whenever JIT is
45        actually used to run the match.
46    
47    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
48        or /S+[+] with a digit between 1 and 7.
49    
50    8.  OP_NOT now supports any UTF character not just single-byte ones.
51    
52    9.  (*MARK) control verb is now supported by the JIT compiler.
53    
54    10. The command "./RunTest list" lists the available tests without actually
55        running any of them. (Because I keep forgetting what they all are.)
56    
57    11. Add PCRE_INFO_MAXLOOKBEHIND.
58    
59    12. Applied a (slightly modified) user-supplied patch that improves performance
60        when the heap is used for recursion (compiled with --disable-stack-for-
61        recursion). Instead of malloc and free for each heap frame each time a
62        logical recursion happens, frames are retained on a chain and re-used where
63        possible. This sometimes gives as much as 30% improvement.
64    
65    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
66        call.
67    
68    14. As documented, (*COMMIT) is now confined to within a positive assertion.
69    
70    15. It is now possible to link pcretest with libedit as an alternative to
71        libreadline.
72    
73    16. (*COMMIT) control verb is now supported by the JIT compiler.
74    
75    17. The Unicode data tables have been updated to Unicode 6.1.0.
76    
77    18. Added --file-list option to pcregrep.
78    
79    19. Added binary file support to pcregrep, including the -a, --binary-files,
80        -I, and --text options.
81    
82    20. The madvise function is renamed for posix_madvise for QNX compatibility
83        reasons. Fixed by Giuseppe D'Angelo.
84    
85    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
86    
87    22. Changed the option for creating symbolic links for 16-bit man pages from
88        -s to -sf so that re-installing does not cause issues.
89    
90    23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.
91    
92    24. Fixed a very old bug in pcretest that caused errors with restarted DFA
93        matches in certain environments (the workspace was not being correctly
94        retained). Also added to pcre_dfa_exec() a simple plausibility check on
95        some of the workspace data at the beginning of a restart.
96    
97    25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
98        was not doing so when it should - probably a typo introduced by SVN 528
99        (change 8.10/14).
100    
101    26. When PCRE_UCP was not set, \w+\x{c4} was incorrectly auto-possessifying the
102        \w+ when the character tables indicated that \x{c4} was a word character.
103        There were several related cases, all because the tests for doing a table
104        lookup were testing for characters less than 127 instead of 255.
105    
106    27. If a pattern contains capturing parentheses that are not used in a match,
107        their slots in the ovector are set to -1. For those that are higher than
108        any matched groups, this happens at the end of processing. In the case when
109        there were back references that the ovector was too small to contain
110        (causing temporary malloc'd memory to be used during matching), and the
111        highest capturing number was not used, memory off the end of the ovector
112        was incorrectly being set to -1. (It was using the size of the temporary
113        memory instead of the true size.)
114    
115    28. To catch bugs like 27 using valgrind, when pcretest is asked to specify an
116        ovector size, it uses memory at the end of the block that it has got.
117    
118    29. Check for an overlong MARK name and give an error at compile time. The
119        limit is 255 for the 8-bit library and 65535 for the 16-bit library.
120    
121    30. JIT compiler update.
122    
123    31. JIT is now supported on jailbroken iOS devices. Thanks for Ruiger
124        Rill for the patch.
125    
126    32. Put spaces around SLJIT_PRINT_D in the JIT compiler. Required by CXX11.
127    
128    33. Variable renamings in the PCRE-JIT compiler. No functionality change.
129    
130    34. Fixed typos in pcregrep: in two places there was SUPPORT_LIBZ2 instead of
131        SUPPORT_LIBBZ2. This caused a build problem when bzip2 but not gzip (zlib)
132        was enabled.
133    
134    35. Improve JIT code generation for greedy plus quantifier.
135    
136    36. When /((?:a?)*)*c/ or /((?>a?)*)*c/ was matched against "aac", it set group
137        1 to "aa" instead of to an empty string. The bug affected repeated groups
138        that could potentially match an empty string.
139    
140    37. Optimizing single character iterators in JIT.
141    
142    38. Wide characters specified with \uxxxx in JavaScript mode are now subject to
143        the same checks as \x{...} characters in non-JavaScript mode. Specifically,
144        codepoints that are too big for the mode are faulted, and in a UTF mode,
145        disallowed codepoints are also faulted.
146    
147    39. If PCRE was compiled with UTF support, in three places in the DFA
148        matcher there was code that should only have been obeyed in UTF mode, but
149        was being obeyed unconditionally. In 8-bit mode this could cause incorrect
150        processing when bytes with values greater than 127 were present. In 16-bit
151        mode the bug would be provoked by values in the range 0xfc00 to 0xdc00. In
152        both cases the values are those that cannot be the first data item in a UTF
153        character. The three items that might have provoked this were recursions,
154        possessively repeated groups, and atomic groups.
155    
156    40. Ensure that libpcre is explicitly listed in the link commands for pcretest
157        and pcregrep, because some OS require shared objects to be explicitly
158        passed to ld, causing the link step to fail if they are not.
159    
160    41. There were two incorrect #ifdefs in pcre_study.c, meaning that, in 16-bit
161        mode, patterns that started with \h* or \R* might be incorrectly matched.
162    
163    
164    Version 8.30 04-February-2012
165    -----------------------------
166    
167    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
168        name is defined in ctype.h.
169    
170    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
171        only in quite long subpatterns.
172    
173    3.  Removed the function pcre_info(), which has been obsolete and deprecated
174        since it was replaced by pcre_fullinfo() in February 2000.
175    
176    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
177        match a (*MARK), and the match failed at the start of the subject, a
178        reference to memory before the start of the subject could occur. This bug
179        was introduced by fix 17 of release 8.21.
180    
181    5.  A reference to an unset group with zero minimum repetition was giving
182        totally wrong answers (in non-JavaScript-compatibility mode). For example,
183        /(another)?(\1?)test/ matched against "hello world test". This bug was
184        introduced in release 8.13.
185    
186    6.  Add support for 16-bit character strings (a large amount of work involving
187        many changes and refactorings).
188    
189    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
190        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
191        from a file.
192    
193    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
194        rounding is not applied in this particular case).
195    
196    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
197        if they appear, or are escaped, in patterns.
198    
199    10. Get rid of a number of -Wunused-but-set-variable warnings.
200    
201    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
202        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
203        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
204        also returns the mark "x". This bug applied to capturing parentheses,
205        non-capturing parentheses, and atomic parentheses. It also applied to some
206        assertions.
207    
208    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
209        information out of configure.ac instead of relying on pcre.h.generic, which
210        is not stored in the repository.
211    
212    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
213        -lreadline.
214    
215    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
216    
217    15. Applied Graycode's patch to put the top-level frame on the stack rather
218        than the heap when not using the stack for recursion. This gives a
219        performance improvement in many cases when recursion is not deep.
220    
221    16. Experimental code added to "pcretest -C" to output the stack frame size.
222    
223    
224    Version 8.21 12-Dec-2011
225    ------------------------
226    
227    1.  Updating the JIT compiler.
228    
229    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
230        are added as well.
231    
232    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
233        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
234        calling _pcre_jit_exec. Some extra comments are added.
235    
236    4.  (*MARK) settings inside atomic groups that do not contain any capturing
237        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
238        was introduced by change 18 for 8.20.
239    
240    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
241        ECMA-262 standard.
242    
243    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
244        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
245        This bug was probably introduced by change 9 of 8.13.
246    
247    7.  While fixing 6 above, I noticed that a number of other items were being
248        incorrectly rejected as "not fixed length". This arose partly because newer
249        opcodes had not been added to the fixed-length checking code. I have (a)
250        corrected the bug and added tests for these items, and (b) arranged for an
251        error to occur if an unknown opcode is encountered while checking for fixed
252        length instead of just assuming "not fixed length". The items that were
253        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
254        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
255        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
256    
257    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
258        being incorrectly compiled and would have given unpredicatble results.
259    
260    9.  A possessively repeated subpattern with minimum repeat count greater than
261        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
262        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
263        the first (A) could occur when it should not.
264    
265    10. Add a cast and remove a redundant test from the code.
266    
267    11. JIT should use pcre_malloc/pcre_free for allocation.
268    
269    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
270        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
271        is anything other than /usr, -L is still shown).
272    
273    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
274    
275    14. Perl does not support \N without a following name in a [] class; PCRE now
276        also gives an error.
277    
278    15. If a forward reference was repeated with an upper limit of around 2000,
279        it caused the error "internal error: overran compiling workspace". The
280        maximum number of forward references (including repeats) was limited by the
281        internal workspace, and dependent on the LINK_SIZE. The code has been
282        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
283        the default depends on LINK_SIZE. There is a new upper limit (for safety)
284        of around 200,000 forward references. While doing this, I also speeded up
285        the filling in of repeated forward references.
286    
287    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
288        incorrectly expecting the subject to contain another "a" after the start.
289    
290    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
291        in the match, the SKIP should be ignored. This was not happening; instead
292        the SKIP was being treated as NOMATCH. For patterns such as
293        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
294        tested.
295    
296    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
297        now much more compatible with Perl, in particular in cases where the result
298        is a non-match for a non-anchored pattern. For example, if
299        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
300        "m", where previously it did not return a name. A side effect of this
301        change is that for partial matches, the last encountered mark name is
302        returned, as for non matches. A number of tests that were previously not
303        Perl-compatible have been moved into the Perl-compatible test files. The
304        refactoring has had the pleasing side effect of removing one argument from
305        the match() function, thus reducing its stack requirements.
306    
307    19. If the /S+ option was used in pcretest to study a pattern using JIT,
308        subsequent uses of /S (without +) incorrectly behaved like /S+.
309    
310    21. Retrieve executable code size support for the JIT compiler and fixing
311        some warnings.
312    
313    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
314        not work when the shorter character appeared right at the end of the
315        subject string.
316    
317    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
318        systems.
319    
320    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
321        output it when the /M option is used in pcretest.
322    
323    25. The CheckMan script was not being included in the distribution. Also, added
324        an explicit "perl" to run Perl scripts from the PrepareRelease script
325        because this is reportedly needed in Windows.
326    
327    26. If study data was being save in a file and studying had not found a set of
328        "starts with" bytes for the pattern, the data written to the file (though
329        never used) was taken from uninitialized memory and so caused valgrind to
330        complain.
331    
332    27. Updated RunTest.bat as provided by Sheri Pierce.
333    
334    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
335    
336    29. Computation of memory usage for the table of capturing group names was
337        giving an unnecessarily large value.
338    
339    
340    Version 8.20 21-Oct-2011
341    ------------------------
342    
343    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
344        a POSIX class. After further experiments with Perl, which convinced me that
345        Perl has bugs and confusions, a closing square bracket is no longer allowed
346        in a POSIX name. This bug also affected patterns with classes that started
347        with full stops.
348    
349    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
350        captured substring, but while checking the failing first alternative,
351        substring 1 is temporarily captured. If the output vector supplied to
352        pcre_exec() was not big enough for this capture, the yield of the function
353        was still zero ("insufficient space for captured substrings"). This cannot
354        be totally fixed without adding another stack variable, which seems a lot
355        of expense for a edge case. However, I have improved the situation in cases
356        such as /(a)(b)x|abc/ matched against "abc", where the return code
357        indicates that fewer than the maximum number of slots in the ovector have
358        been set.
359    
360    3.  Related to (2) above: when there are more back references in a pattern than
361        slots in the output vector, pcre_exec() uses temporary memory during
362        matching, and copies in the captures as far as possible afterwards. It was
363        using the entire output vector, but this conflicts with the specification
364        that only 2/3 is used for passing back captured substrings. Now it uses
365        only the first 2/3, for compatibility. This is, of course, another edge
366        case.
367    
368    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
369        main code base, and can be used by building with --enable-jit. When this is
370        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
371        runtime --no-jit option is given.
372    
373    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
374        ovector, the return from the function was zero, implying that there were
375        other matches that did not fit. The correct "exactly full" value is now
376        returned.
377    
378    6.  If a subpattern that was called recursively or as a subroutine contained
379        (*PRUNE) or any other control that caused it to give a non-standard return,
380        invalid errors such as "Error -26 (nested recursion at the same subject
381        position)" or even infinite loops could occur.
382    
383    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
384        computing the minimum length on reaching *ACCEPT, and so ended up with the
385        wrong value of 1 rather than 0. Further investigation indicates that
386        computing a minimum subject length in the presence of *ACCEPT is difficult
387        (think back references, subroutine calls), and so I have changed the code
388        so that no minimum is registered for a pattern that contains *ACCEPT.
389    
390    8.  If (*THEN) was present in the first (true) branch of a conditional group,
391        it was not handled as intended. [But see 16 below.]
392    
393    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
394        Sheri Pierce.
395    
396    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
397        the first byte in a match must be "a".
398    
399    11. Change 17 for 8.13 increased the recursion depth for patterns like
400        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
401        pattern contains any instances of (*THEN). If it does not, the old
402        optimizations are restored. It would be nice to do this on a per-group
403        basis, but at the moment that is not feasible.
404    
405    12. In some environments, the output of pcretest -C is CRLF terminated. This
406        broke RunTest's code that checks for the link size. A single white space
407        character after the value is now allowed for.
408    
409    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
410        For "fr", it uses the Windows-specific input and output files.
411    
412    14. If (*THEN) appeared in a group that was called recursively or as a
413        subroutine, it did not work as intended. [But see next item.]
414    
415    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
416        pattern fragments (but not containing any | characters). If A and B are
417        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
418        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
419        D. In other words, Perl considers parentheses that do not contain any |
420        characters to be part of a surrounding alternative, whereas PCRE was
421        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
422        differently. PCRE now behaves in the same way as Perl, except in the case
423        of subroutine/recursion calls such as (?1) which have in any case always
424        been different (but PCRE had them first :-).
425    
426    16. Related to 15 above: Perl does not treat the | in a conditional group as
427        creating alternatives. Such a group is treated in the same way as an
428        ordinary group without any | characters when processing (*THEN). PCRE has
429        been changed to match Perl's behaviour.
430    
431    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
432        RunGrepTest script failed.
433    
434    18. Change 22 for version 13 caused atomic groups to use more stack. This is
435        inevitable for groups that contain captures, but it can lead to a lot of
436        stack use in large patterns. The old behaviour has been restored for atomic
437        groups that do not contain any capturing parentheses.
438    
439    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
440        suppress the check for a minimum subject length at run time. (If it was
441        given to pcre_exec() or pcre_dfa_exec() it did work.)
442    
443    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
444        fail to work when decoding hex characters in data strings in EBCDIC
445        environments.
446    
447    21. It appears that in at least one Mac OS environment, the isxdigit() function
448        is implemented as a macro that evaluates to its argument more than once,
449        contravening the C 90 Standard (I haven't checked a later standard). There
450        was an instance in pcretest which caused it to go wrong when processing
451        \x{...} escapes in subject strings. The has been rewritten to avoid using
452        things like p++ in the argument of isxdigit().
453    
454    
455    Version 8.13 16-Aug-2011
456  ------------------------  ------------------------
457    
458  1.  The Unicode data tables have been updated to Unicode 6.0.0.  1.  The Unicode data tables have been updated to Unicode 6.0.0.
# Line 20  Version 8.13 30-Apr-2011 Line 471  Version 8.13 30-Apr-2011
471      code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a      code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
472      2-byte code at the end of the subject (it thought there wasn't enough data      2-byte code at the end of the subject (it thought there wasn't enough data
473      left).      left).
474    
475  5.  Comprehensive information about what went wrong is now returned by  5.  Comprehensive information about what went wrong is now returned by
476      pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long      pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
477      as the output vector has at least 2 elements. The offset of the start of      as the output vector has at least 2 elements. The offset of the start of
478      the failing character and a reason code are placed in the vector.      the failing character and a reason code are placed in the vector.
479    
480  6.  When the UTF-8 string check fails for pcre_compile(), the offset that is  6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
481      now returned is for the first byte of the failing character, instead of the      now returned is for the first byte of the failing character, instead of the
482      last byte inspected. This is an incompatible change, but I hope it is small      last byte inspected. This is an incompatible change, but I hope it is small
483      enough not to be a problem. It makes the returned offset consistent with      enough not to be a problem. It makes the returned offset consistent with
484      pcre_exec() and pcre_dfa_exec().      pcre_exec() and pcre_dfa_exec().
485    
486  7.  pcretest now gives a text phrase as well as the error number when  7.  pcretest now gives a text phrase as well as the error number when
487      pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check      pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
488      failure, the offset and reason code are output.      failure, the offset and reason code are output.
489    
490  8.  When \R was used with a maximizing quantifier it failed to skip backwards  8.  When \R was used with a maximizing quantifier it failed to skip backwards
491      over a \r\n pair if the subsequent match failed. Instead, it just skipped      over a \r\n pair if the subsequent match failed. Instead, it just skipped
492      back over a single character (\n). This seems wrong (because it treated the      back over a single character (\n). This seems wrong (because it treated the
493      two characters as a single entity when going forwards), conflicts with the      two characters as a single entity when going forwards), conflicts with the
494      documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the      documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
495      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
496      has been changed.      has been changed.
497    
498  9.  Some internal refactoring has changed the processing so that the handling  9.  Some internal refactoring has changed the processing so that the handling
499      of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile      of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
500      time (the PCRE_DOTALL option was changed this way some time ago: version      time (the PCRE_DOTALL option was changed this way some time ago: version
501      7.7 change 16). This has made it possible to abolish the OP_OPT op code,      7.7 change 16). This has made it possible to abolish the OP_OPT op code,
502      which was always a bit of a fudge. It also means that there is one less      which was always a bit of a fudge. It also means that there is one less
503      argument for the match() function, which reduces its stack requirements      argument for the match() function, which reduces its stack requirements
504      slightly. This change also fixes an incompatibility with Perl: the pattern      slightly. This change also fixes an incompatibility with Perl: the pattern
505      (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.      (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
506    
507  10. More internal refactoring has drastically reduced the number of recursive  10. More internal refactoring has drastically reduced the number of recursive
508      calls to match() for possessively repeated groups such as (abc)++ when      calls to match() for possessively repeated groups such as (abc)++ when
509      using pcre_exec().      using pcre_exec().
510    
511  11. While implementing 10, a number of bugs in the handling of groups were  11. While implementing 10, a number of bugs in the handling of groups were
512      discovered and fixed:      discovered and fixed:
513    
514      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
515      (a|)*(?1) gave a compile-time internal error.      (a|)*(?1) gave a compile-time internal error.
516      ((a|)+)+  did not notice that the outer group could match an empty string.      ((a|)+)+  did not notice that the outer group could match an empty string.
517      (^a|^)+   was not marked as anchored.      (^a|^)+   was not marked as anchored.
518      (.*a|.*)+ was not marked as matching at start or after a newline.      (.*a|.*)+ was not marked as matching at start or after a newline.
519    
520  12. Yet more internal refactoring has removed another argument from the match()  12. Yet more internal refactoring has removed another argument from the match()
521      function. Special calls to this function are now indicated by setting a      function. Special calls to this function are now indicated by setting a
522      value in a variable in the "match data" data block.      value in a variable in the "match data" data block.
523    
524    13. Be more explicit in pcre_study() instead of relying on "default" for
525        opcodes that mean there is no starting character; this means that when new
526        ones are added and accidentally left out of pcre_study(), testing should
527        pick them up.
528    
529    14. The -s option of pcretest has been documented for ages as being an old
530        synonym of -m (show memory usage). I have changed it to mean "force study
531        for every regex", that is, assume /S for every regex. This is similar to -i
532        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
533        using it. It makes it easier to run collections of tests with and without
534        study enabled, and thereby test pcre_study() more easily. All the standard
535        tests are now run with and without -s (but some patterns can be marked as
536        "never study" - see 20 below).
537    
538    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
539        restoration of the capturing data to the outer values was not happening
540        correctly.
541    
542    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
543        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
544        pattern had matched an empty string, and so incorrectly returned a no
545        match.
546    
547    17. There was optimizing code for the last branch of non-capturing parentheses,
548        and also for the obeyed branch of a conditional subexpression, which used
549        tail recursion to cut down on stack usage. Unfortunately, now that there is
550        the possibility of (*THEN) occurring in these branches, tail recursion is
551        no longer possible because the return has to be checked for (*THEN). These
552        two optimizations have therefore been removed. [But see 8.20/11 above.]
553    
554    18. If a pattern containing \R was studied, it was assumed that \R always
555        matched two bytes, thus causing the minimum subject length to be
556        incorrectly computed because \R can also match just one byte.
557    
558    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
559        was incorrectly computed.
560    
561    20. If /S is present twice on a test pattern in pcretest input, it now
562        *disables* studying, thereby overriding the use of -s on the command line
563        (see 14 above). This is necessary for one or two tests to keep the output
564        identical in both cases.
565    
566    21. When (*ACCEPT) was used in an assertion that matched an empty string and
567        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
568    
569    22. When an atomic group that contained a capturing parenthesis was
570        successfully matched, but the branch in which it appeared failed, the
571        capturing was not being forgotten if a higher numbered group was later
572        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
573        group 1 to "a", when in fact it should be unset. This applied to multi-
574        branched capturing and non-capturing groups, repeated or not, and also to
575        positive assertions (capturing in negative assertions does not happen
576        in PCRE) and also to nested atomic groups.
577    
578    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
579        subject after a captured substring, to make it easier to tell which of a
580        number of identical substrings has been captured.
581    
582    24. The way atomic groups are processed by pcre_exec() has been changed so that
583        if they are repeated, backtracking one repetition now resets captured
584        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
585        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
586        "aaa". Previously, it would have been "a". As part of this code
587        refactoring, the way recursive calls are handled has also been changed.
588    
589    25. If an assertion condition captured any substrings, they were not passed
590        back unless some other capturing happened later. For example, if
591        (?(?=(a))a) was matched against "a", no capturing was returned.
592    
593    26. When studying a pattern that contained subroutine calls or assertions,
594        the code for finding the minimum length of a possible match was handling
595        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
596        group 1 called group 2 while simultaneously a separate group 2 called group
597        1). A stack overflow occurred in this case. I have fixed this by limiting
598        the recursion depth to 10.
599    
600    27. Updated RunTest.bat in the distribution to the version supplied by Tom
601        Fortmann. This supports explicit test numbers on the command line, and has
602        argument validation and error reporting.
603    
604    28. An instance of \X with an unlimited repeat could fail if at any point the
605        first character it looked at was a mark character.
606    
607    29. Some minor code refactoring concerning Unicode properties and scripts
608        should reduce the stack requirement of match() slightly.
609    
610    30. Added the '=' option to pcretest to check the setting of unused capturing
611        slots at the end of the pattern, which are documented as being -1, but are
612        not included in the return count.
613    
614    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
615        compiled something random. Now it gives a compile-time error (as does
616        Perl).
617    
618    32. A *MARK encountered during the processing of a positive assertion is now
619        recorded and passed back (compatible with Perl).
620    
621    33. If --only-matching or --colour was set on a pcregrep call whose pattern
622        had alternative anchored branches, the search for a second match in a line
623        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
624        matched the line "0102" twice. The same bug affected patterns that started
625        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
626        twice.
627    
628    34. Previously, PCRE did not allow quantification of assertions. However, Perl
629        does, and because of capturing effects, quantifying parenthesized
630        assertions may at times be useful. Quantifiers are now allowed for
631        parenthesized assertions.
632    
633    35. A minor code tidy in pcre_compile() when checking options for \R usage.
634    
635    36. \g was being checked for fancy things in a character class, when it should
636        just be a literal "g".
637    
638    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
639        appearance of a nested POSIX class supersedes an apparent external class.
640        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
641        unescaped square brackets may also appear as part of class names. For
642        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
643        more like Perl. (But see 8.20/1 above.)
644    
645    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
646        was because it thought it was \N{name}, which is not supported).
647    
648    39. Add minix to OS list not supporting the -S option in pcretest.
649    
650    40. PCRE tries to detect cases of infinite recursion at compile time, but it
651        cannot analyze patterns in sufficient detail to catch mutual recursions
652        such as ((?1))((?2)). There is now a runtime test that gives an error if a
653        subgroup is called recursively as a subpattern for a second time at the
654        same position in the subject string. In previous releases this might have
655        been caught by the recursion limit, or it might have run out of stack.
656    
657    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
658        happen only once. PCRE was, however incorrectly giving a compile time error
659        "recursive call could loop indefinitely" because it cannot analyze the
660        pattern in sufficient detail. The compile time test no longer happens when
661        PCRE is compiling a conditional subpattern, but actual runaway loops are
662        now caught at runtime (see 40 above).
663    
664    42. It seems that Perl allows any characters other than a closing parenthesis
665        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
666        has been changed to be the same.
667    
668    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
669        as not to get warnings when autogen.sh is called. Also changed
670        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
671    
672    44. To help people who use pcregrep to scan files containing exceedingly long
673        lines, the following changes have been made:
674    
675        (a) The default value of the buffer size parameter has been increased from
676            8K to 20K. (The actual buffer used is three times this size.)
677    
678        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
679            PCRE is built.
680    
681        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
682            to be set at run time.
683    
684        (d) Numerical values in pcregrep options can be followed by K or M, for
685            example --buffer-size=50K.
686    
687        (e) If a line being scanned overflows pcregrep's buffer, an error is now
688            given and the return code is set to 2.
689    
690    45. Add a pointer to the latest mark to the callout data block.
691    
692    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
693        partial match of an empty string instead of no match. This was specific to
694        the use of ".".
695    
696    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
697        complete match instead of a partial match. This bug was dependent on both
698        the PCRE_UTF8 and PCRE_DOTALL options being set.
699    
700    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
701        starting byte set, because \b was not being ignored.
702    
703    
704  Version 8.12 15-Jan-2011  Version 8.12 15-Jan-2011

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