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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 8.01 06-Jan-10  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.
113    Version 8.20 21-Oct-2011
114    ------------------------
116    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
117        a POSIX class. After further experiments with Perl, which convinced me that
118        Perl has bugs and confusions, a closing square bracket is no longer allowed
119        in a POSIX name. This bug also affected patterns with classes that started
120        with full stops.
122    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
123        captured substring, but while checking the failing first alternative,
124        substring 1 is temporarily captured. If the output vector supplied to
125        pcre_exec() was not big enough for this capture, the yield of the function
126        was still zero ("insufficient space for captured substrings"). This cannot
127        be totally fixed without adding another stack variable, which seems a lot
128        of expense for a edge case. However, I have improved the situation in cases
129        such as /(a)(b)x|abc/ matched against "abc", where the return code
130        indicates that fewer than the maximum number of slots in the ovector have
131        been set.
133    3.  Related to (2) above: when there are more back references in a pattern than
134        slots in the output vector, pcre_exec() uses temporary memory during
135        matching, and copies in the captures as far as possible afterwards. It was
136        using the entire output vector, but this conflicts with the specification
137        that only 2/3 is used for passing back captured substrings. Now it uses
138        only the first 2/3, for compatibility. This is, of course, another edge
139        case.
141    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
142        main code base, and can be used by building with --enable-jit. When this is
143        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
144        runtime --no-jit option is given.
146    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
147        ovector, the return from the function was zero, implying that there were
148        other matches that did not fit. The correct "exactly full" value is now
149        returned.
151    6.  If a subpattern that was called recursively or as a subroutine contained
152        (*PRUNE) or any other control that caused it to give a non-standard return,
153        invalid errors such as "Error -26 (nested recursion at the same subject
154        position)" or even infinite loops could occur.
156    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
157        computing the minimum length on reaching *ACCEPT, and so ended up with the
158        wrong value of 1 rather than 0. Further investigation indicates that
159        computing a minimum subject length in the presence of *ACCEPT is difficult
160        (think back references, subroutine calls), and so I have changed the code
161        so that no minimum is registered for a pattern that contains *ACCEPT.
163    8.  If (*THEN) was present in the first (true) branch of a conditional group,
164        it was not handled as intended. [But see 16 below.]
166    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
167        Sheri Pierce.
169    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
170        the first byte in a match must be "a".
172    11. Change 17 for 8.13 increased the recursion depth for patterns like
173        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
174        pattern contains any instances of (*THEN). If it does not, the old
175        optimizations are restored. It would be nice to do this on a per-group
176        basis, but at the moment that is not feasible.
178    12. In some environments, the output of pcretest -C is CRLF terminated. This
179        broke RunTest's code that checks for the link size. A single white space
180        character after the value is now allowed for.
182    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
183        For "fr", it uses the Windows-specific input and output files.
185    14. If (*THEN) appeared in a group that was called recursively or as a
186        subroutine, it did not work as intended. [But see next item.]
188    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
189        pattern fragments (but not containing any | characters). If A and B are
190        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
191        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
192        D. In other words, Perl considers parentheses that do not contain any |
193        characters to be part of a surrounding alternative, whereas PCRE was
194        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
195        differently. PCRE now behaves in the same way as Perl, except in the case
196        of subroutine/recursion calls such as (?1) which have in any case always
197        been different (but PCRE had them first :-).
199    16. Related to 15 above: Perl does not treat the | in a conditional group as
200        creating alternatives. Such a group is treated in the same way as an
201        ordinary group without any | characters when processing (*THEN). PCRE has
202        been changed to match Perl's behaviour.
204    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
205        RunGrepTest script failed.
207    18. Change 22 for version 13 caused atomic groups to use more stack. This is
208        inevitable for groups that contain captures, but it can lead to a lot of
209        stack use in large patterns. The old behaviour has been restored for atomic
210        groups that do not contain any capturing parentheses.
212    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
213        suppress the check for a minimum subject length at run time. (If it was
214        given to pcre_exec() or pcre_dfa_exec() it did work.)
216    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
217        fail to work when decoding hex characters in data strings in EBCDIC
218        environments.
220    21. It appears that in at least one Mac OS environment, the isxdigit() function
221        is implemented as a macro that evaluates to its argument more than once,
222        contravening the C 90 Standard (I haven't checked a later standard). There
223        was an instance in pcretest which caused it to go wrong when processing
224        \x{...} escapes in subject strings. The has been rewritten to avoid using
225        things like p++ in the argument of isxdigit().
228    Version 8.13 16-Aug-2011
229    ------------------------
231    1.  The Unicode data tables have been updated to Unicode 6.0.0.
233    2.  Two minor typos in pcre_internal.h have been fixed.
235    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
236        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
237        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
239    4.  There were a number of related bugs in the code for matching backrefences
240        caselessly in UTF-8 mode when codes for the characters concerned were
241        different numbers of bytes. For example, U+023A and U+2C65 are an upper
242        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
243        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
244        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
245        2-byte code at the end of the subject (it thought there wasn't enough data
246        left).
248    5.  Comprehensive information about what went wrong is now returned by
249        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
250        as the output vector has at least 2 elements. The offset of the start of
251        the failing character and a reason code are placed in the vector.
253    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
254        now returned is for the first byte of the failing character, instead of the
255        last byte inspected. This is an incompatible change, but I hope it is small
256        enough not to be a problem. It makes the returned offset consistent with
257        pcre_exec() and pcre_dfa_exec().
259    7.  pcretest now gives a text phrase as well as the error number when
260        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
261        failure, the offset and reason code are output.
263    8.  When \R was used with a maximizing quantifier it failed to skip backwards
264        over a \r\n pair if the subsequent match failed. Instead, it just skipped
265        back over a single character (\n). This seems wrong (because it treated the
266        two characters as a single entity when going forwards), conflicts with the
267        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
268        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
269        has been changed.
271    9.  Some internal refactoring has changed the processing so that the handling
272        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
273        time (the PCRE_DOTALL option was changed this way some time ago: version
274        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
275        which was always a bit of a fudge. It also means that there is one less
276        argument for the match() function, which reduces its stack requirements
277        slightly. This change also fixes an incompatibility with Perl: the pattern
278        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
280    10. More internal refactoring has drastically reduced the number of recursive
281        calls to match() for possessively repeated groups such as (abc)++ when
282        using pcre_exec().
284    11. While implementing 10, a number of bugs in the handling of groups were
285        discovered and fixed:
287        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
288        (a|)*(?1) gave a compile-time internal error.
289        ((a|)+)+  did not notice that the outer group could match an empty string.
290        (^a|^)+   was not marked as anchored.
291        (.*a|.*)+ was not marked as matching at start or after a newline.
293    12. Yet more internal refactoring has removed another argument from the match()
294        function. Special calls to this function are now indicated by setting a
295        value in a variable in the "match data" data block.
297    13. Be more explicit in pcre_study() instead of relying on "default" for
298        opcodes that mean there is no starting character; this means that when new
299        ones are added and accidentally left out of pcre_study(), testing should
300        pick them up.
302    14. The -s option of pcretest has been documented for ages as being an old
303        synonym of -m (show memory usage). I have changed it to mean "force study
304        for every regex", that is, assume /S for every regex. This is similar to -i
305        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
306        using it. It makes it easier to run collections of tests with and without
307        study enabled, and thereby test pcre_study() more easily. All the standard
308        tests are now run with and without -s (but some patterns can be marked as
309        "never study" - see 20 below).
311    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
312        restoration of the capturing data to the outer values was not happening
313        correctly.
315    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
316        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
317        pattern had matched an empty string, and so incorrectly returned a no
318        match.
320    17. There was optimizing code for the last branch of non-capturing parentheses,
321        and also for the obeyed branch of a conditional subexpression, which used
322        tail recursion to cut down on stack usage. Unfortunately, now that there is
323        the possibility of (*THEN) occurring in these branches, tail recursion is
324        no longer possible because the return has to be checked for (*THEN). These
325        two optimizations have therefore been removed. [But see 8.20/11 above.]
327    18. If a pattern containing \R was studied, it was assumed that \R always
328        matched two bytes, thus causing the minimum subject length to be
329        incorrectly computed because \R can also match just one byte.
331    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
332        was incorrectly computed.
334    20. If /S is present twice on a test pattern in pcretest input, it now
335        *disables* studying, thereby overriding the use of -s on the command line
336        (see 14 above). This is necessary for one or two tests to keep the output
337        identical in both cases.
339    21. When (*ACCEPT) was used in an assertion that matched an empty string and
340        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
342    22. When an atomic group that contained a capturing parenthesis was
343        successfully matched, but the branch in which it appeared failed, the
344        capturing was not being forgotten if a higher numbered group was later
345        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
346        group 1 to "a", when in fact it should be unset. This applied to multi-
347        branched capturing and non-capturing groups, repeated or not, and also to
348        positive assertions (capturing in negative assertions does not happen
349        in PCRE) and also to nested atomic groups.
351    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
352        subject after a captured substring, to make it easier to tell which of a
353        number of identical substrings has been captured.
355    24. The way atomic groups are processed by pcre_exec() has been changed so that
356        if they are repeated, backtracking one repetition now resets captured
357        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
358        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
359        "aaa". Previously, it would have been "a". As part of this code
360        refactoring, the way recursive calls are handled has also been changed.
362    25. If an assertion condition captured any substrings, they were not passed
363        back unless some other capturing happened later. For example, if
364        (?(?=(a))a) was matched against "a", no capturing was returned.
366    26. When studying a pattern that contained subroutine calls or assertions,
367        the code for finding the minimum length of a possible match was handling
368        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
369        group 1 called group 2 while simultaneously a separate group 2 called group
370        1). A stack overflow occurred in this case. I have fixed this by limiting
371        the recursion depth to 10.
373    27. Updated RunTest.bat in the distribution to the version supplied by Tom
374        Fortmann. This supports explicit test numbers on the command line, and has
375        argument validation and error reporting.
377    28. An instance of \X with an unlimited repeat could fail if at any point the
378        first character it looked at was a mark character.
380    29. Some minor code refactoring concerning Unicode properties and scripts
381        should reduce the stack requirement of match() slightly.
383    30. Added the '=' option to pcretest to check the setting of unused capturing
384        slots at the end of the pattern, which are documented as being -1, but are
385        not included in the return count.
387    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
388        compiled something random. Now it gives a compile-time error (as does
389        Perl).
391    32. A *MARK encountered during the processing of a positive assertion is now
392        recorded and passed back (compatible with Perl).
394    33. If --only-matching or --colour was set on a pcregrep call whose pattern
395        had alternative anchored branches, the search for a second match in a line
396        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
397        matched the line "0102" twice. The same bug affected patterns that started
398        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
399        twice.
401    34. Previously, PCRE did not allow quantification of assertions. However, Perl
402        does, and because of capturing effects, quantifying parenthesized
403        assertions may at times be useful. Quantifiers are now allowed for
404        parenthesized assertions.
406    35. A minor code tidy in pcre_compile() when checking options for \R usage.
408    36. \g was being checked for fancy things in a character class, when it should
409        just be a literal "g".
411    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
412        appearance of a nested POSIX class supersedes an apparent external class.
413        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
414        unescaped square brackets may also appear as part of class names. For
415        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
416        more like Perl. (But see 8.20/1 above.)
418    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
419        was because it thought it was \N{name}, which is not supported).
421    39. Add minix to OS list not supporting the -S option in pcretest.
423    40. PCRE tries to detect cases of infinite recursion at compile time, but it
424        cannot analyze patterns in sufficient detail to catch mutual recursions
425        such as ((?1))((?2)). There is now a runtime test that gives an error if a
426        subgroup is called recursively as a subpattern for a second time at the
427        same position in the subject string. In previous releases this might have
428        been caught by the recursion limit, or it might have run out of stack.
430    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
431        happen only once. PCRE was, however incorrectly giving a compile time error
432        "recursive call could loop indefinitely" because it cannot analyze the
433        pattern in sufficient detail. The compile time test no longer happens when
434        PCRE is compiling a conditional subpattern, but actual runaway loops are
435        now caught at runtime (see 40 above).
437    42. It seems that Perl allows any characters other than a closing parenthesis
438        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
439        has been changed to be the same.
441    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
442        as not to get warnings when autogen.sh is called. Also changed
443        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
445    44. To help people who use pcregrep to scan files containing exceedingly long
446        lines, the following changes have been made:
448        (a) The default value of the buffer size parameter has been increased from
449            8K to 20K. (The actual buffer used is three times this size.)
451        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
452            PCRE is built.
454        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
455            to be set at run time.
457        (d) Numerical values in pcregrep options can be followed by K or M, for
458            example --buffer-size=50K.
460        (e) If a line being scanned overflows pcregrep's buffer, an error is now
461            given and the return code is set to 2.
463    45. Add a pointer to the latest mark to the callout data block.
465    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
466        partial match of an empty string instead of no match. This was specific to
467        the use of ".".
469    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
470        complete match instead of a partial match. This bug was dependent on both
471        the PCRE_UTF8 and PCRE_DOTALL options being set.
473    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
474        starting byte set, because \b was not being ignored.
477    Version 8.12 15-Jan-2011
478    ------------------------
480    1.  Fixed some typos in the markup of the man pages, and wrote a script that
481        checks for such things as part of the documentation building process.
483    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
484        --match-limit and --recursion-limit options (added for 8.11). In
485        particular, this made one of the standard tests fail. (The integer value
486        went into the wrong half of a long int.)
488    3.  If the --colour option was given to pcregrep with -v (invert match), it
489        did strange things, either producing crazy output, or crashing. It should,
490        of course, ignore a request for colour when reporting lines that do not
491        match.
493    4.  Another pcregrep bug caused similar problems if --colour was specified with
494        -M (multiline) and the pattern match finished with a line ending.
496    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
497        matched in multiline mode, the following line was shown as part of the
498        match. This seems wrong, so I have changed it.
500    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
501        the check for further matches in the same line (so they could be coloured)
502        to overrun the end of the current line. If another match was found, it was
503        incorrectly shown (and then shown again when found in the next line).
505    7.  If pcregrep was compiled under Windows, there was a reference to the
506        function pcregrep_exit() before it was defined. I am assuming this was
507        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
508        reported by a user. I've moved the definition above the reference.
511    Version 8.11 10-Dec-2010
512    ------------------------
514    1.  (*THEN) was not working properly if there were untried alternatives prior
515        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
516        backtracked to try for "b" instead of moving to the next alternative branch
517        at the same level (in this case, to look for "c"). The Perl documentation
518        is clear that when (*THEN) is backtracked onto, it goes to the "next
519        alternative in the innermost enclosing group".
521    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
522        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
523        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
524        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
525        (*THEN).
527    3.  If \s appeared in a character class, it removed the VT character from
528        the class, even if it had been included by some previous item, for example
529        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
530        of \s, but is part of the POSIX "space" class.)
532    4.  A partial match never returns an empty string (because you can always
533        match an empty string at the end of the subject); however the checking for
534        an empty string was starting at the "start of match" point. This has been
535        changed to the "earliest inspected character" point, because the returned
536        data for a partial match starts at this character. This means that, for
537        example, /(?<=abc)def/ gives a partial match for the subject "abc"
538        (previously it gave "no match").
540    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
541        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
542        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
543        has an implication that the given string is incomplete (because a partial
544        match is preferred over a full match). For this reason, these items now
545        give a partial match in this situation. [Aside: previously, the one case
546        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
547        match rather than a full match, which was wrong by the old rules, but is
548        now correct.]
550    6.  There was a bug in the handling of #-introduced comments, recognized when
551        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
552        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
553        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
554        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
555        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
556        places in pcre_compile().
558    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
559        comments when looking ahead for named forward references to subpatterns,
560        the only newline sequence it recognized was NL. It now handles newlines
561        according to the set newline convention.
563    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
564        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
565        cater for a lack of strerror(). These oversights have been fixed.
567    9.  Added --match-limit and --recursion-limit to pcregrep.
569    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
571    11. When the -o option was used, pcregrep was setting a return code of 1, even
572        when matches were found, and --line-buffered was not being honoured.
574    12. Added an optional parentheses number to the -o and --only-matching options
575        of pcregrep.
577    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
578        can match an empty string. The code to do it in pcretest and pcredemo
579        needed fixing:
581        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
582            only one byte after an empty string match just before CRLF (this case
583            just got forgotten; "any" and "anycrlf" were OK).
585        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
586            mode when an empty string match preceded an ASCII character followed by
587            a non-ASCII character. (The code for advancing by one character rather
588            than one byte was nonsense.)
590        (c) The pcredemo.c sample program did not have any code at all to handle
591            the cases when CRLF is a valid newline sequence.
593    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
594        as a starting offset was within the subject string. There is now a new
595        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
596        negative or greater than the length of the string. In order to test this,
597        pcretest is extended to allow the setting of negative starting offsets.
599    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
600        starting offset points to the beginning of a UTF-8 character was
601        unnecessarily clumsy. I tidied it up.
603    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
604        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
606    17. Nobody had reported that the --include_dir option, which was added in
607        release 7.7 should have been called --include-dir (hyphen, not underscore)
608        for compatibility with GNU grep. I have changed it to --include-dir, but
609        left --include_dir as an undocumented synonym, and the same for
610        --exclude-dir, though that is not available in GNU grep, at least as of
611        release 2.5.4.
613    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
614        characters from a string of bytes) have been redefined so as not to use
615        loops, in order to improve performance in some environments. At the same
616        time, I abstracted some of the common code into auxiliary macros to save
617        repetition (this should not affect the compiled code).
619    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
620        compile-time error is now given if \c is not followed by an ASCII
621        character, that is, a byte less than 128. (In EBCDIC mode, the code is
622        different, and any byte value is allowed.)
624    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
625        START_OPTIMIZE option, which is now allowed at compile time - but just
626        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
627        to pcregrep and other applications that have no direct access to PCRE
628        options. The new /Y option in pcretest sets this option when calling
629        pcre_compile().
631    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
632        back references. Groups containing recursive back references were forced to
633        be atomic by that change, but in the case of named groups, the amount of
634        memory required was incorrectly computed, leading to "Failed: internal
635        error: code overflow". This has been fixed.
637    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
638        pcretest.c, to avoid build problems in some Borland environments.
641    Version 8.10 25-Jun-2010
642    ------------------------
644    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
645        THEN.
647    2.  (*ACCEPT) was not working when inside an atomic group.
649    3.  Inside a character class, \B is treated as a literal by default, but
650        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
651        causes the error). The code is unchanged, but I tidied the documentation.
653    4.  Inside a character class, PCRE always treated \R and \X as literals,
654        whereas Perl faults them if its -w option is set. I have changed PCRE so
655        that it faults them when PCRE_EXTRA is set.
657    5.  Added support for \N, which always matches any character other than
658        newline. (It is the same as "." when PCRE_DOTALL is not set.)
660    6.  When compiling pcregrep with newer versions of gcc which may have
661        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
662        declared with attribute warn_unused_result" were given. Just casting the
663        result to (void) does not stop the warnings; a more elaborate fudge is
664        needed. I've used a macro to implement this.
666    7.  Minor change to pcretest.c to avoid a compiler warning.
668    8.  Added four artifical Unicode properties to help with an option to make
669        \s etc use properties (see next item). The new properties are: Xan
670        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
672    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
673        use Unicode properties. (*UCP) at the start of a pattern can be used to set
674        this option. Modified pcretest to add /W to test this facility. Added
675        REG_UCP to make it available via the POSIX interface.
677    10. Added --line-buffered to pcregrep.
679    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
680        studied, and the match started with a letter with a code point greater than
681        127 whose first byte was different to the first byte of the other case of
682        the letter, the other case of this starting letter was not recognized
683        (#976).
685    12. If a pattern that was studied started with a repeated Unicode property
686        test, for example, \p{Nd}+, there was the theoretical possibility of
687        setting up an incorrect bitmap of starting bytes, but fortunately it could
688        not have actually happened in practice until change 8 above was made (it
689        added property types that matched character-matching opcodes).
691    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
692        possible starting bytes for non-anchored patterns.
694    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
695        \R, and also a number of cases that involve Unicode properties, both
696        explicit and implicit when PCRE_UCP is set.
698    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
699        input, it could crash or give wrong results if characters with values
700        greater than 0xc0 were present in the subject string. (Detail: it assumed
701        UTF-8 input when processing these items.)
703    16. Added a lot of (int) casts to avoid compiler warnings in systems where
704        size_t is 64-bit (#991).
706    17. Added a check for running out of memory when PCRE is compiled with
707        --disable-stack-for-recursion (#990).
709    18. If the last data line in a file for pcretest does not have a newline on
710        the end, a newline was missing in the output.
712    19. The default pcre_chartables.c file recognizes only ASCII characters (values
713        less than 128) in its various bitmaps. However, there is a facility for
714        generating tables according to the current locale when PCRE is compiled. It
715        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
716        characters, are recognized by isspace() and therefore were getting set in
717        these tables, and indeed these tables seem to approximate to ISO 8859. This
718        caused a problem in UTF-8 mode when pcre_study() was used to create a list
719        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
720        which of course cannot start UTF-8 characters. I have changed the code so
721        that only real ASCII characters (less than 128) and the correct starting
722        bytes for UTF-8 encodings are set for characters greater than 127 when in
723        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
724        altogether.)
726    20. Added the /T option to pcretest so as to be able to run tests with non-
727        standard character tables, thus making it possible to include the tests
728        used for 19 above in the standard set of tests.
730    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
731        reference to a subpattern the other side of a comment that contains an
732        opening parenthesis caused either an internal compiling error, or a
733        reference to the wrong subpattern.
736    Version 8.02 19-Mar-2010
737    ------------------------
739    1.  The Unicode data tables have been updated to Unicode 5.2.0.
741    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
742        configured.
744    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
745        original author of that file, following a query about its status.
747    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
748        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
750    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
751        quantifier applied to a forward-referencing subroutine call, could compile
752        incorrect code or give the error "internal error: previously-checked
753        referenced subpattern not found".
755    6.  Both MS Visual Studio and Symbian OS have problems with initializing
756        variables to point to external functions. For these systems, therefore,
757        pcre_malloc etc. are now initialized to local functions that call the
758        relevant global functions.
760    7.  There were two entries missing in the vectors called coptable and poptable
761        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
762        I've fixed the data, and added a kludgy way of testing at compile time that
763        the lengths are correct (equal to the number of opcodes).
765    8.  Following on from 7, I added a similar kludge to check the length of the
766        eint vector in pcreposix.c.
768    9.  Error texts for pcre_compile() are held as one long string to avoid too
769        much relocation at load time. To find a text, the string is searched,
770        counting zeros. There was no check for running off the end of the string,
771        which could happen if a new error number was added without updating the
772        string.
774    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
776    11. \K was not working if it appeared in an atomic group or in a group that
777        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
778        \K is "not well defined" if used in an assertion. PCRE now accepts it if
779        the assertion is positive, but not if it is negative.
781    12. Change 11 fortuitously reduced the size of the stack frame used in the
782        "match()" function of pcre_exec.c by one pointer. Forthcoming
783        implementation of support for (*MARK) will need an extra pointer on the
784        stack; I have reserved it now, so that the stack frame size does not
785        decrease.
787    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
788        item in branch that calls a recursion is a subroutine call - as in the
789        second branch in the above example - was incorrectly given the compile-
790        time error "recursive call could loop indefinitely" because pcre_compile()
791        was not correctly checking the subroutine for matching a non-empty string.
793    14. The checks for overrunning compiling workspace could trigger after an
794        overrun had occurred. This is a "should never occur" error, but it can be
795        triggered by pathological patterns such as hundreds of nested parentheses.
796        The checks now trigger 100 bytes before the end of the workspace.
798    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
801    Version 8.01 19-Jan-2010
802    ------------------------
804  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
805      particular, this includes all (DEFINE) patterns), a call to pcre_study()      particular, this includes all (*DEFINE) patterns), a call to pcre_study()
806      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
807      subpatterns).      subpatterns). This could cause incorrect "no match" results.
809  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
810      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 61  Version 8.01 06-Jan-10 Line 858  Version 8.01 06-Jan-10
858      custom one, because of the following reported problem in Windows:      custom one, because of the following reported problem in Windows:
860        - libbz2 uses the Pascal calling convention (WINAPI) for the functions        - libbz2 uses the Pascal calling convention (WINAPI) for the functions
861          under Win32.            under Win32.
862        - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",        - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
863          therefore missing the function definition.            therefore missing the function definition.
864        - The compiler thus generates a "C" signature for the test function.        - The compiler thus generates a "C" signature for the test function.
865        - The linker fails to find the "C" function.        - The linker fails to find the "C" function.
866        - PCRE fails to configure if asked to do so against libbz2.        - PCRE fails to configure if asked to do so against libbz2.
# Line 113  Version 8.01 06-Jan-10 Line 910  Version 8.01 06-Jan-10
910      equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for      equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
911      instance, but it only takes 2 args instead of 3!"      instance, but it only takes 2 args instead of 3!"
913    18. A subtle bug concerned with back references has been fixed by a change of
914        specification, with a corresponding code fix. A pattern such as
915        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
916        refers, was giving matches when it shouldn't. For example, xa=xaaa would
917        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
918        same bug. Such groups have to be quantified to be useful, or contained
919        inside another quantified group. (If there's no repetition, the reference
920        can never match.) The problem arises because, having left the group and
921        moved on to the rest of the pattern, a later failure that backtracks into
922        the group uses the captured value from the final iteration of the group
923        rather than the correct earlier one. I have fixed this in PCRE by forcing
924        any group that contains a reference to itself to be an atomic group; that
925        is, there cannot be any backtracking into it once it has completed. This is
926        similar to recursive and subroutine calls.
929  Version 8.00 19-Oct-09  Version 8.00 19-Oct-09
930  ----------------------  ----------------------

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