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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 8.01 11-Dec-09  Version 8.21 05-Dec-2011
5  ----------------------  ------------------------
7    1.  Updating the JIT compiler.
9    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
10        are added as well.
12    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
13        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
14        calling _pcre_jit_exec. Some extra comments are added.
16    4.  (*MARK) settings inside atomic groups that do not contain any capturing
17        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
18        was introduced by change 18 for 8.20.
20    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
21        ECMA-262 standard.
23    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
24        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
25        This bug was probably introduced by change 9 of 8.13.
27    7.  While fixing 6 above, I noticed that a number of other items were being
28        incorrectly rejected as "not fixed length". This arose partly because newer
29        opcodes had not been added to the fixed-length checking code. I have (a)
30        corrected the bug and added tests for these items, and (b) arranged for an
31        error to occur if an unknown opcode is encountered while checking for fixed
32        length instead of just assuming "not fixed length". The items that were
33        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
34        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
35        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
37    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
38        being incorrectly compiled and would have given unpredicatble results.
40    9.  A possessively repeated subpattern with minimum repeat count greater than
41        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
42        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
43        the first (A) could occur when it should not.
45    10. Add a cast and remove a redundant test from the code.
47    11. JIT should use pcre_malloc/pcre_free for allocation.
49    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
50        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
51        is anything other than /usr, -L is still shown).
53    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
55    14. Perl does not support \N without a following name in a [] class; PCRE now
56        also gives an error.
58    15. If a forward reference was repeated with an upper limit of around 2000,
59        it caused the error "internal error: overran compiling workspace". The
60        maximum number of forward references (including repeats) was limited by the
61        internal workspace, and dependent on the LINK_SIZE. The code has been
62        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
63        the default depends on LINK_SIZE. There is a new upper limit (for safety)
64        of around 200,000 forward references. While doing this, I also speeded up
65        the filling in of repeated forward references.
67    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
68        incorrectly expecting the subject to contain another "a" after the start.
70    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
71        in the match, the SKIP should be ignored. This was not happening; instead
72        the SKIP was being treated as NOMATCH. For patterns such as
73        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
74        tested.
76    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
77        now much more compatible with Perl, in particular in cases where the result
78        is a non-match for a non-anchored pattern. For example, if
79        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
80        "m", where previously it did not return a name. A side effect of this
81        change is that for partial matches, the last encountered mark name is
82        returned, as for non matches. A number of tests that were previously not
83        Perl-compatible have been moved into the Perl-compatible test files. The
84        refactoring has had the pleasing side effect of removing one argument from
85        the match() function, thus reducing its stack requirements.
87    19. If the /S+ option was used in pcretest to study a pattern using JIT,
88        subsequent uses of /S (without +) incorrectly behaved like /S+.
90    21. Retrieve executable code size support for the JIT compiler and fixing
91        some warnings.
93    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
94        not work when the shorter character appeared right at the end of the
95        subject string.
97    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
98        systems.
100    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
101        output it when the /M option is used in pcretest.
103    25. The CheckMan script was not being included in the distribution. Also, added
104        an explicit "perl" to run Perl scripts from the PrepareRelease script
105        because this is reportedly needed in Windows.
107    26. If study data was being save in a file and studying had not found a set of
108        "starts with" bytes for the pattern, the data written to the file (though
109        never used) was taken from uninitialized memory and so caused valgrind to
110        complain.
112    27. Updated RunTest.bat as provided by Sheri Pierce.
114    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
116    29. Computation of memory usage for the table of capturing group names was
117        giving an unnecessarily large value.
120    Version 8.20 21-Oct-2011
121    ------------------------
123    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
124        a POSIX class. After further experiments with Perl, which convinced me that
125        Perl has bugs and confusions, a closing square bracket is no longer allowed
126        in a POSIX name. This bug also affected patterns with classes that started
127        with full stops.
129    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
130        captured substring, but while checking the failing first alternative,
131        substring 1 is temporarily captured. If the output vector supplied to
132        pcre_exec() was not big enough for this capture, the yield of the function
133        was still zero ("insufficient space for captured substrings"). This cannot
134        be totally fixed without adding another stack variable, which seems a lot
135        of expense for a edge case. However, I have improved the situation in cases
136        such as /(a)(b)x|abc/ matched against "abc", where the return code
137        indicates that fewer than the maximum number of slots in the ovector have
138        been set.
140    3.  Related to (2) above: when there are more back references in a pattern than
141        slots in the output vector, pcre_exec() uses temporary memory during
142        matching, and copies in the captures as far as possible afterwards. It was
143        using the entire output vector, but this conflicts with the specification
144        that only 2/3 is used for passing back captured substrings. Now it uses
145        only the first 2/3, for compatibility. This is, of course, another edge
146        case.
148    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
149        main code base, and can be used by building with --enable-jit. When this is
150        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
151        runtime --no-jit option is given.
153    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
154        ovector, the return from the function was zero, implying that there were
155        other matches that did not fit. The correct "exactly full" value is now
156        returned.
158    6.  If a subpattern that was called recursively or as a subroutine contained
159        (*PRUNE) or any other control that caused it to give a non-standard return,
160        invalid errors such as "Error -26 (nested recursion at the same subject
161        position)" or even infinite loops could occur.
163    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
164        computing the minimum length on reaching *ACCEPT, and so ended up with the
165        wrong value of 1 rather than 0. Further investigation indicates that
166        computing a minimum subject length in the presence of *ACCEPT is difficult
167        (think back references, subroutine calls), and so I have changed the code
168        so that no minimum is registered for a pattern that contains *ACCEPT.
170    8.  If (*THEN) was present in the first (true) branch of a conditional group,
171        it was not handled as intended. [But see 16 below.]
173    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
174        Sheri Pierce.
176    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
177        the first byte in a match must be "a".
179    11. Change 17 for 8.13 increased the recursion depth for patterns like
180        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
181        pattern contains any instances of (*THEN). If it does not, the old
182        optimizations are restored. It would be nice to do this on a per-group
183        basis, but at the moment that is not feasible.
185    12. In some environments, the output of pcretest -C is CRLF terminated. This
186        broke RunTest's code that checks for the link size. A single white space
187        character after the value is now allowed for.
189    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
190        For "fr", it uses the Windows-specific input and output files.
192    14. If (*THEN) appeared in a group that was called recursively or as a
193        subroutine, it did not work as intended. [But see next item.]
195    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
196        pattern fragments (but not containing any | characters). If A and B are
197        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
198        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
199        D. In other words, Perl considers parentheses that do not contain any |
200        characters to be part of a surrounding alternative, whereas PCRE was
201        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
202        differently. PCRE now behaves in the same way as Perl, except in the case
203        of subroutine/recursion calls such as (?1) which have in any case always
204        been different (but PCRE had them first :-).
206    16. Related to 15 above: Perl does not treat the | in a conditional group as
207        creating alternatives. Such a group is treated in the same way as an
208        ordinary group without any | characters when processing (*THEN). PCRE has
209        been changed to match Perl's behaviour.
211    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
212        RunGrepTest script failed.
214    18. Change 22 for version 13 caused atomic groups to use more stack. This is
215        inevitable for groups that contain captures, but it can lead to a lot of
216        stack use in large patterns. The old behaviour has been restored for atomic
217        groups that do not contain any capturing parentheses.
219    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
220        suppress the check for a minimum subject length at run time. (If it was
221        given to pcre_exec() or pcre_dfa_exec() it did work.)
223    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
224        fail to work when decoding hex characters in data strings in EBCDIC
225        environments.
227    21. It appears that in at least one Mac OS environment, the isxdigit() function
228        is implemented as a macro that evaluates to its argument more than once,
229        contravening the C 90 Standard (I haven't checked a later standard). There
230        was an instance in pcretest which caused it to go wrong when processing
231        \x{...} escapes in subject strings. The has been rewritten to avoid using
232        things like p++ in the argument of isxdigit().
235    Version 8.13 16-Aug-2011
236    ------------------------
238    1.  The Unicode data tables have been updated to Unicode 6.0.0.
240    2.  Two minor typos in pcre_internal.h have been fixed.
242    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
243        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
244        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
246    4.  There were a number of related bugs in the code for matching backrefences
247        caselessly in UTF-8 mode when codes for the characters concerned were
248        different numbers of bytes. For example, U+023A and U+2C65 are an upper
249        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
250        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
251        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
252        2-byte code at the end of the subject (it thought there wasn't enough data
253        left).
255    5.  Comprehensive information about what went wrong is now returned by
256        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
257        as the output vector has at least 2 elements. The offset of the start of
258        the failing character and a reason code are placed in the vector.
260    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
261        now returned is for the first byte of the failing character, instead of the
262        last byte inspected. This is an incompatible change, but I hope it is small
263        enough not to be a problem. It makes the returned offset consistent with
264        pcre_exec() and pcre_dfa_exec().
266    7.  pcretest now gives a text phrase as well as the error number when
267        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
268        failure, the offset and reason code are output.
270    8.  When \R was used with a maximizing quantifier it failed to skip backwards
271        over a \r\n pair if the subsequent match failed. Instead, it just skipped
272        back over a single character (\n). This seems wrong (because it treated the
273        two characters as a single entity when going forwards), conflicts with the
274        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
275        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
276        has been changed.
278    9.  Some internal refactoring has changed the processing so that the handling
279        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
280        time (the PCRE_DOTALL option was changed this way some time ago: version
281        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
282        which was always a bit of a fudge. It also means that there is one less
283        argument for the match() function, which reduces its stack requirements
284        slightly. This change also fixes an incompatibility with Perl: the pattern
285        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
287    10. More internal refactoring has drastically reduced the number of recursive
288        calls to match() for possessively repeated groups such as (abc)++ when
289        using pcre_exec().
291    11. While implementing 10, a number of bugs in the handling of groups were
292        discovered and fixed:
294        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
295        (a|)*(?1) gave a compile-time internal error.
296        ((a|)+)+  did not notice that the outer group could match an empty string.
297        (^a|^)+   was not marked as anchored.
298        (.*a|.*)+ was not marked as matching at start or after a newline.
300    12. Yet more internal refactoring has removed another argument from the match()
301        function. Special calls to this function are now indicated by setting a
302        value in a variable in the "match data" data block.
304    13. Be more explicit in pcre_study() instead of relying on "default" for
305        opcodes that mean there is no starting character; this means that when new
306        ones are added and accidentally left out of pcre_study(), testing should
307        pick them up.
309    14. The -s option of pcretest has been documented for ages as being an old
310        synonym of -m (show memory usage). I have changed it to mean "force study
311        for every regex", that is, assume /S for every regex. This is similar to -i
312        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
313        using it. It makes it easier to run collections of tests with and without
314        study enabled, and thereby test pcre_study() more easily. All the standard
315        tests are now run with and without -s (but some patterns can be marked as
316        "never study" - see 20 below).
318    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
319        restoration of the capturing data to the outer values was not happening
320        correctly.
322    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
323        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
324        pattern had matched an empty string, and so incorrectly returned a no
325        match.
327    17. There was optimizing code for the last branch of non-capturing parentheses,
328        and also for the obeyed branch of a conditional subexpression, which used
329        tail recursion to cut down on stack usage. Unfortunately, now that there is
330        the possibility of (*THEN) occurring in these branches, tail recursion is
331        no longer possible because the return has to be checked for (*THEN). These
332        two optimizations have therefore been removed. [But see 8.20/11 above.]
334    18. If a pattern containing \R was studied, it was assumed that \R always
335        matched two bytes, thus causing the minimum subject length to be
336        incorrectly computed because \R can also match just one byte.
338    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
339        was incorrectly computed.
341    20. If /S is present twice on a test pattern in pcretest input, it now
342        *disables* studying, thereby overriding the use of -s on the command line
343        (see 14 above). This is necessary for one or two tests to keep the output
344        identical in both cases.
346    21. When (*ACCEPT) was used in an assertion that matched an empty string and
347        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
349    22. When an atomic group that contained a capturing parenthesis was
350        successfully matched, but the branch in which it appeared failed, the
351        capturing was not being forgotten if a higher numbered group was later
352        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
353        group 1 to "a", when in fact it should be unset. This applied to multi-
354        branched capturing and non-capturing groups, repeated or not, and also to
355        positive assertions (capturing in negative assertions does not happen
356        in PCRE) and also to nested atomic groups.
358    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
359        subject after a captured substring, to make it easier to tell which of a
360        number of identical substrings has been captured.
362    24. The way atomic groups are processed by pcre_exec() has been changed so that
363        if they are repeated, backtracking one repetition now resets captured
364        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
365        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
366        "aaa". Previously, it would have been "a". As part of this code
367        refactoring, the way recursive calls are handled has also been changed.
369    25. If an assertion condition captured any substrings, they were not passed
370        back unless some other capturing happened later. For example, if
371        (?(?=(a))a) was matched against "a", no capturing was returned.
373    26. When studying a pattern that contained subroutine calls or assertions,
374        the code for finding the minimum length of a possible match was handling
375        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
376        group 1 called group 2 while simultaneously a separate group 2 called group
377        1). A stack overflow occurred in this case. I have fixed this by limiting
378        the recursion depth to 10.
380    27. Updated RunTest.bat in the distribution to the version supplied by Tom
381        Fortmann. This supports explicit test numbers on the command line, and has
382        argument validation and error reporting.
384    28. An instance of \X with an unlimited repeat could fail if at any point the
385        first character it looked at was a mark character.
387    29. Some minor code refactoring concerning Unicode properties and scripts
388        should reduce the stack requirement of match() slightly.
390    30. Added the '=' option to pcretest to check the setting of unused capturing
391        slots at the end of the pattern, which are documented as being -1, but are
392        not included in the return count.
394    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
395        compiled something random. Now it gives a compile-time error (as does
396        Perl).
398    32. A *MARK encountered during the processing of a positive assertion is now
399        recorded and passed back (compatible with Perl).
401    33. If --only-matching or --colour was set on a pcregrep call whose pattern
402        had alternative anchored branches, the search for a second match in a line
403        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
404        matched the line "0102" twice. The same bug affected patterns that started
405        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
406        twice.
408    34. Previously, PCRE did not allow quantification of assertions. However, Perl
409        does, and because of capturing effects, quantifying parenthesized
410        assertions may at times be useful. Quantifiers are now allowed for
411        parenthesized assertions.
413    35. A minor code tidy in pcre_compile() when checking options for \R usage.
415    36. \g was being checked for fancy things in a character class, when it should
416        just be a literal "g".
418    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
419        appearance of a nested POSIX class supersedes an apparent external class.
420        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
421        unescaped square brackets may also appear as part of class names. For
422        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
423        more like Perl. (But see 8.20/1 above.)
425    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
426        was because it thought it was \N{name}, which is not supported).
428    39. Add minix to OS list not supporting the -S option in pcretest.
430    40. PCRE tries to detect cases of infinite recursion at compile time, but it
431        cannot analyze patterns in sufficient detail to catch mutual recursions
432        such as ((?1))((?2)). There is now a runtime test that gives an error if a
433        subgroup is called recursively as a subpattern for a second time at the
434        same position in the subject string. In previous releases this might have
435        been caught by the recursion limit, or it might have run out of stack.
437    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
438        happen only once. PCRE was, however incorrectly giving a compile time error
439        "recursive call could loop indefinitely" because it cannot analyze the
440        pattern in sufficient detail. The compile time test no longer happens when
441        PCRE is compiling a conditional subpattern, but actual runaway loops are
442        now caught at runtime (see 40 above).
444    42. It seems that Perl allows any characters other than a closing parenthesis
445        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
446        has been changed to be the same.
448    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
449        as not to get warnings when autogen.sh is called. Also changed
450        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
452    44. To help people who use pcregrep to scan files containing exceedingly long
453        lines, the following changes have been made:
455        (a) The default value of the buffer size parameter has been increased from
456            8K to 20K. (The actual buffer used is three times this size.)
458        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
459            PCRE is built.
461        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
462            to be set at run time.
464        (d) Numerical values in pcregrep options can be followed by K or M, for
465            example --buffer-size=50K.
467        (e) If a line being scanned overflows pcregrep's buffer, an error is now
468            given and the return code is set to 2.
470    45. Add a pointer to the latest mark to the callout data block.
472    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
473        partial match of an empty string instead of no match. This was specific to
474        the use of ".".
476    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
477        complete match instead of a partial match. This bug was dependent on both
478        the PCRE_UTF8 and PCRE_DOTALL options being set.
480    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
481        starting byte set, because \b was not being ignored.
484    Version 8.12 15-Jan-2011
485    ------------------------
487    1.  Fixed some typos in the markup of the man pages, and wrote a script that
488        checks for such things as part of the documentation building process.
490    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
491        --match-limit and --recursion-limit options (added for 8.11). In
492        particular, this made one of the standard tests fail. (The integer value
493        went into the wrong half of a long int.)
495    3.  If the --colour option was given to pcregrep with -v (invert match), it
496        did strange things, either producing crazy output, or crashing. It should,
497        of course, ignore a request for colour when reporting lines that do not
498        match.
500    4.  Another pcregrep bug caused similar problems if --colour was specified with
501        -M (multiline) and the pattern match finished with a line ending.
503    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
504        matched in multiline mode, the following line was shown as part of the
505        match. This seems wrong, so I have changed it.
507    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
508        the check for further matches in the same line (so they could be coloured)
509        to overrun the end of the current line. If another match was found, it was
510        incorrectly shown (and then shown again when found in the next line).
512    7.  If pcregrep was compiled under Windows, there was a reference to the
513        function pcregrep_exit() before it was defined. I am assuming this was
514        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
515        reported by a user. I've moved the definition above the reference.
518    Version 8.11 10-Dec-2010
519    ------------------------
521    1.  (*THEN) was not working properly if there were untried alternatives prior
522        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
523        backtracked to try for "b" instead of moving to the next alternative branch
524        at the same level (in this case, to look for "c"). The Perl documentation
525        is clear that when (*THEN) is backtracked onto, it goes to the "next
526        alternative in the innermost enclosing group".
528    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
529        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
530        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
531        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
532        (*THEN).
534    3.  If \s appeared in a character class, it removed the VT character from
535        the class, even if it had been included by some previous item, for example
536        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
537        of \s, but is part of the POSIX "space" class.)
539    4.  A partial match never returns an empty string (because you can always
540        match an empty string at the end of the subject); however the checking for
541        an empty string was starting at the "start of match" point. This has been
542        changed to the "earliest inspected character" point, because the returned
543        data for a partial match starts at this character. This means that, for
544        example, /(?<=abc)def/ gives a partial match for the subject "abc"
545        (previously it gave "no match").
547    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
548        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
549        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
550        has an implication that the given string is incomplete (because a partial
551        match is preferred over a full match). For this reason, these items now
552        give a partial match in this situation. [Aside: previously, the one case
553        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
554        match rather than a full match, which was wrong by the old rules, but is
555        now correct.]
557    6.  There was a bug in the handling of #-introduced comments, recognized when
558        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
559        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
560        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
561        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
562        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
563        places in pcre_compile().
565    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
566        comments when looking ahead for named forward references to subpatterns,
567        the only newline sequence it recognized was NL. It now handles newlines
568        according to the set newline convention.
570    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
571        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
572        cater for a lack of strerror(). These oversights have been fixed.
574    9.  Added --match-limit and --recursion-limit to pcregrep.
576    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
578    11. When the -o option was used, pcregrep was setting a return code of 1, even
579        when matches were found, and --line-buffered was not being honoured.
581    12. Added an optional parentheses number to the -o and --only-matching options
582        of pcregrep.
584    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
585        can match an empty string. The code to do it in pcretest and pcredemo
586        needed fixing:
588        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
589            only one byte after an empty string match just before CRLF (this case
590            just got forgotten; "any" and "anycrlf" were OK).
592        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
593            mode when an empty string match preceded an ASCII character followed by
594            a non-ASCII character. (The code for advancing by one character rather
595            than one byte was nonsense.)
597        (c) The pcredemo.c sample program did not have any code at all to handle
598            the cases when CRLF is a valid newline sequence.
600    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
601        as a starting offset was within the subject string. There is now a new
602        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
603        negative or greater than the length of the string. In order to test this,
604        pcretest is extended to allow the setting of negative starting offsets.
606    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
607        starting offset points to the beginning of a UTF-8 character was
608        unnecessarily clumsy. I tidied it up.
610    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
611        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
613    17. Nobody had reported that the --include_dir option, which was added in
614        release 7.7 should have been called --include-dir (hyphen, not underscore)
615        for compatibility with GNU grep. I have changed it to --include-dir, but
616        left --include_dir as an undocumented synonym, and the same for
617        --exclude-dir, though that is not available in GNU grep, at least as of
618        release 2.5.4.
620    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
621        characters from a string of bytes) have been redefined so as not to use
622        loops, in order to improve performance in some environments. At the same
623        time, I abstracted some of the common code into auxiliary macros to save
624        repetition (this should not affect the compiled code).
626    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
627        compile-time error is now given if \c is not followed by an ASCII
628        character, that is, a byte less than 128. (In EBCDIC mode, the code is
629        different, and any byte value is allowed.)
631    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
632        START_OPTIMIZE option, which is now allowed at compile time - but just
633        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
634        to pcregrep and other applications that have no direct access to PCRE
635        options. The new /Y option in pcretest sets this option when calling
636        pcre_compile().
638    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
639        back references. Groups containing recursive back references were forced to
640        be atomic by that change, but in the case of named groups, the amount of
641        memory required was incorrectly computed, leading to "Failed: internal
642        error: code overflow". This has been fixed.
644    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
645        pcretest.c, to avoid build problems in some Borland environments.
648    Version 8.10 25-Jun-2010
649    ------------------------
651    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
652        THEN.
654    2.  (*ACCEPT) was not working when inside an atomic group.
656    3.  Inside a character class, \B is treated as a literal by default, but
657        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
658        causes the error). The code is unchanged, but I tidied the documentation.
660    4.  Inside a character class, PCRE always treated \R and \X as literals,
661        whereas Perl faults them if its -w option is set. I have changed PCRE so
662        that it faults them when PCRE_EXTRA is set.
664    5.  Added support for \N, which always matches any character other than
665        newline. (It is the same as "." when PCRE_DOTALL is not set.)
667    6.  When compiling pcregrep with newer versions of gcc which may have
668        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
669        declared with attribute warn_unused_result" were given. Just casting the
670        result to (void) does not stop the warnings; a more elaborate fudge is
671        needed. I've used a macro to implement this.
673    7.  Minor change to pcretest.c to avoid a compiler warning.
675    8.  Added four artifical Unicode properties to help with an option to make
676        \s etc use properties (see next item). The new properties are: Xan
677        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
679    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
680        use Unicode properties. (*UCP) at the start of a pattern can be used to set
681        this option. Modified pcretest to add /W to test this facility. Added
682        REG_UCP to make it available via the POSIX interface.
684    10. Added --line-buffered to pcregrep.
686    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
687        studied, and the match started with a letter with a code point greater than
688        127 whose first byte was different to the first byte of the other case of
689        the letter, the other case of this starting letter was not recognized
690        (#976).
692    12. If a pattern that was studied started with a repeated Unicode property
693        test, for example, \p{Nd}+, there was the theoretical possibility of
694        setting up an incorrect bitmap of starting bytes, but fortunately it could
695        not have actually happened in practice until change 8 above was made (it
696        added property types that matched character-matching opcodes).
698    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
699        possible starting bytes for non-anchored patterns.
701    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
702        \R, and also a number of cases that involve Unicode properties, both
703        explicit and implicit when PCRE_UCP is set.
705    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
706        input, it could crash or give wrong results if characters with values
707        greater than 0xc0 were present in the subject string. (Detail: it assumed
708        UTF-8 input when processing these items.)
710    16. Added a lot of (int) casts to avoid compiler warnings in systems where
711        size_t is 64-bit (#991).
713    17. Added a check for running out of memory when PCRE is compiled with
714        --disable-stack-for-recursion (#990).
716    18. If the last data line in a file for pcretest does not have a newline on
717        the end, a newline was missing in the output.
719    19. The default pcre_chartables.c file recognizes only ASCII characters (values
720        less than 128) in its various bitmaps. However, there is a facility for
721        generating tables according to the current locale when PCRE is compiled. It
722        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
723        characters, are recognized by isspace() and therefore were getting set in
724        these tables, and indeed these tables seem to approximate to ISO 8859. This
725        caused a problem in UTF-8 mode when pcre_study() was used to create a list
726        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
727        which of course cannot start UTF-8 characters. I have changed the code so
728        that only real ASCII characters (less than 128) and the correct starting
729        bytes for UTF-8 encodings are set for characters greater than 127 when in
730        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
731        altogether.)
733    20. Added the /T option to pcretest so as to be able to run tests with non-
734        standard character tables, thus making it possible to include the tests
735        used for 19 above in the standard set of tests.
737    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
738        reference to a subpattern the other side of a comment that contains an
739        opening parenthesis caused either an internal compiling error, or a
740        reference to the wrong subpattern.
743    Version 8.02 19-Mar-2010
744    ------------------------
746    1.  The Unicode data tables have been updated to Unicode 5.2.0.
748    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
749        configured.
751    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
752        original author of that file, following a query about its status.
754    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
755        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
757    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
758        quantifier applied to a forward-referencing subroutine call, could compile
759        incorrect code or give the error "internal error: previously-checked
760        referenced subpattern not found".
762    6.  Both MS Visual Studio and Symbian OS have problems with initializing
763        variables to point to external functions. For these systems, therefore,
764        pcre_malloc etc. are now initialized to local functions that call the
765        relevant global functions.
767    7.  There were two entries missing in the vectors called coptable and poptable
768        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
769        I've fixed the data, and added a kludgy way of testing at compile time that
770        the lengths are correct (equal to the number of opcodes).
772    8.  Following on from 7, I added a similar kludge to check the length of the
773        eint vector in pcreposix.c.
775    9.  Error texts for pcre_compile() are held as one long string to avoid too
776        much relocation at load time. To find a text, the string is searched,
777        counting zeros. There was no check for running off the end of the string,
778        which could happen if a new error number was added without updating the
779        string.
781    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
783    11. \K was not working if it appeared in an atomic group or in a group that
784        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
785        \K is "not well defined" if used in an assertion. PCRE now accepts it if
786        the assertion is positive, but not if it is negative.
788    12. Change 11 fortuitously reduced the size of the stack frame used in the
789        "match()" function of pcre_exec.c by one pointer. Forthcoming
790        implementation of support for (*MARK) will need an extra pointer on the
791        stack; I have reserved it now, so that the stack frame size does not
792        decrease.
794    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
795        item in branch that calls a recursion is a subroutine call - as in the
796        second branch in the above example - was incorrectly given the compile-
797        time error "recursive call could loop indefinitely" because pcre_compile()
798        was not correctly checking the subroutine for matching a non-empty string.
800    14. The checks for overrunning compiling workspace could trigger after an
801        overrun had occurred. This is a "should never occur" error, but it can be
802        triggered by pathological patterns such as hundreds of nested parentheses.
803        The checks now trigger 100 bytes before the end of the workspace.
805    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
808    Version 8.01 19-Jan-2010
809    ------------------------
811  1.  If a pattern contained a conditional subpattern with only one branch (in  1.  If a pattern contained a conditional subpattern with only one branch (in
812      particular, this includes all (DEFINE) patterns), a call to pcre_study()      particular, this includes all (*DEFINE) patterns), a call to pcre_study()
813      computed the wrong minimum data length (which is of course zero for such      computed the wrong minimum data length (which is of course zero for such
814      subpatterns).      subpatterns). This could cause incorrect "no match" results.
816  2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of  2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
817      the pattern is reset in the first branch, pcre_compile() failed with      the pattern is reset in the first branch, pcre_compile() failed with
# Line 26  Version 8.01 11-Dec-09 Line 830  Version 8.01 11-Dec-09
830      assertion subpattern, including such a pattern used as a condition,      assertion subpattern, including such a pattern used as a condition,
831      unpredictable results occurred, instead of the error return      unpredictable results occurred, instead of the error return
834  5.  The C++ GlobalReplace function was not working like Perl for the special  5.  The C++ GlobalReplace function was not working like Perl for the special
835      situation when an empty string is matched. It now does the fancy magic      situation when an empty string is matched. It now does the fancy magic
836      stuff that is necessary.      stuff that is necessary.
838    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
839        removed. (These were left over from very, very early versions of PCRE.)
841    7.  Some cosmetic changes to the code to make life easier when compiling it
842        as part of something else:
844        (a) Change DEBUG to PCRE_DEBUG.
846        (b) In pcre_compile(), rename the member of the "branch_chain" structure
847            called "current" as "current_branch", to prevent a collision with the
848            Linux macro when compiled as a kernel module.
850        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
851            prevent a collision with the Linux macro when compiled as a kernel
852            module.
854    8.  In pcre_compile() there are some checks for integer overflows that used to
855        cast potentially large values to (double). This has been changed to that
856        when building, a check for int64_t is made, and if it is found, it is used
857        instead, thus avoiding the use of floating point arithmetic. (There is no
858        other use of FP in PCRE.) If int64_t is not found, the fallback is to
859        double.
861    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
862        2005 (difference between two addresses compared to an unsigned value).
864    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
865        custom one, because of the following reported problem in Windows:
867          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
868              under Win32.
869          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
870              therefore missing the function definition.
871          - The compiler thus generates a "C" signature for the test function.
872          - The linker fails to find the "C" function.
873          - PCRE fails to configure if asked to do so against libbz2.
875    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
876        messages were output:
878          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
879          rerunning libtoolize, to keep the correct libtool macros in-tree.
880          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
882        I have done both of these things.
884    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
885        most of the time, it *can* run out if it is given a pattern that contains a
886        runaway infinite recursion. I updated the discussion in the pcrestack man
887        page.
889    13. Now that we have gone to the x.xx style of version numbers, the minor
890        version may start with zero. Using 08 or 09 is a bad idea because users
891        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
892        interpreted as invalid octal numbers. I've updated the previous comment in
893        configure.ac, and also added a check that gives an error if 08 or 09 are
894        used.
896    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
897        causing partial matching to fail when the end of the subject matched \W
898        in a UTF-8 pattern where \W was quantified with a minimum of 3.
900    15. There were some discrepancies between the declarations in pcre_internal.h
901        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
902        their definitions. The declarations used "const uschar *" and the
903        definitions used USPTR. Even though USPTR is normally defined as "const
904        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
905        reported that: "This difference in casting confuses some C++ compilers, for
906        example, SunCC recognizes above declarations as different functions and
907        generates broken code for hbpcre." I have changed the declarations to use
908        USPTR.
910    16. GNU libtool is named differently on some systems. The autogen.sh script now
911        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
912        (FreeBSD).
914    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
915        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
916        comment: "Figure out how to create a longlong from a string: strtoll and
917        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
918        instance, but it only takes 2 args instead of 3!"
920    18. A subtle bug concerned with back references has been fixed by a change of
921        specification, with a corresponding code fix. A pattern such as
922        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
923        refers, was giving matches when it shouldn't. For example, xa=xaaa would
924        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
925        same bug. Such groups have to be quantified to be useful, or contained
926        inside another quantified group. (If there's no repetition, the reference
927        can never match.) The problem arises because, having left the group and
928        moved on to the rest of the pattern, a later failure that backtracks into
929        the group uses the captured value from the final iteration of the group
930        rather than the correct earlier one. I have fixed this in PCRE by forcing
931        any group that contains a reference to itself to be an atomic group; that
932        is, there cannot be any backtracking into it once it has completed. This is
933        similar to recursive and subroutine calls.
936  Version 8.00 19-Oct-09  Version 8.00 19-Oct-09

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