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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 7.1 05-Mar-07  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.
108    Version 8.20 21-Oct-2011
109    ------------------------
111    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
112        a POSIX class. After further experiments with Perl, which convinced me that
113        Perl has bugs and confusions, a closing square bracket is no longer allowed
114        in a POSIX name. This bug also affected patterns with classes that started
115        with full stops.
117    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
118        captured substring, but while checking the failing first alternative,
119        substring 1 is temporarily captured. If the output vector supplied to
120        pcre_exec() was not big enough for this capture, the yield of the function
121        was still zero ("insufficient space for captured substrings"). This cannot
122        be totally fixed without adding another stack variable, which seems a lot
123        of expense for a edge case. However, I have improved the situation in cases
124        such as /(a)(b)x|abc/ matched against "abc", where the return code
125        indicates that fewer than the maximum number of slots in the ovector have
126        been set.
128    3.  Related to (2) above: when there are more back references in a pattern than
129        slots in the output vector, pcre_exec() uses temporary memory during
130        matching, and copies in the captures as far as possible afterwards. It was
131        using the entire output vector, but this conflicts with the specification
132        that only 2/3 is used for passing back captured substrings. Now it uses
133        only the first 2/3, for compatibility. This is, of course, another edge
134        case.
136    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
137        main code base, and can be used by building with --enable-jit. When this is
138        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
139        runtime --no-jit option is given.
141    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
142        ovector, the return from the function was zero, implying that there were
143        other matches that did not fit. The correct "exactly full" value is now
144        returned.
146    6.  If a subpattern that was called recursively or as a subroutine contained
147        (*PRUNE) or any other control that caused it to give a non-standard return,
148        invalid errors such as "Error -26 (nested recursion at the same subject
149        position)" or even infinite loops could occur.
151    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
152        computing the minimum length on reaching *ACCEPT, and so ended up with the
153        wrong value of 1 rather than 0. Further investigation indicates that
154        computing a minimum subject length in the presence of *ACCEPT is difficult
155        (think back references, subroutine calls), and so I have changed the code
156        so that no minimum is registered for a pattern that contains *ACCEPT.
158    8.  If (*THEN) was present in the first (true) branch of a conditional group,
159        it was not handled as intended. [But see 16 below.]
161    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
162        Sheri Pierce.
164    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
165        the first byte in a match must be "a".
167    11. Change 17 for 8.13 increased the recursion depth for patterns like
168        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
169        pattern contains any instances of (*THEN). If it does not, the old
170        optimizations are restored. It would be nice to do this on a per-group
171        basis, but at the moment that is not feasible.
173    12. In some environments, the output of pcretest -C is CRLF terminated. This
174        broke RunTest's code that checks for the link size. A single white space
175        character after the value is now allowed for.
177    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
178        For "fr", it uses the Windows-specific input and output files.
180    14. If (*THEN) appeared in a group that was called recursively or as a
181        subroutine, it did not work as intended. [But see next item.]
183    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
184        pattern fragments (but not containing any | characters). If A and B are
185        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
186        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
187        D. In other words, Perl considers parentheses that do not contain any |
188        characters to be part of a surrounding alternative, whereas PCRE was
189        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
190        differently. PCRE now behaves in the same way as Perl, except in the case
191        of subroutine/recursion calls such as (?1) which have in any case always
192        been different (but PCRE had them first :-).
194    16. Related to 15 above: Perl does not treat the | in a conditional group as
195        creating alternatives. Such a group is treated in the same way as an
196        ordinary group without any | characters when processing (*THEN). PCRE has
197        been changed to match Perl's behaviour.
199    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
200        RunGrepTest script failed.
202    18. Change 22 for version 13 caused atomic groups to use more stack. This is
203        inevitable for groups that contain captures, but it can lead to a lot of
204        stack use in large patterns. The old behaviour has been restored for atomic
205        groups that do not contain any capturing parentheses.
207    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
208        suppress the check for a minimum subject length at run time. (If it was
209        given to pcre_exec() or pcre_dfa_exec() it did work.)
211    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
212        fail to work when decoding hex characters in data strings in EBCDIC
213        environments.
215    21. It appears that in at least one Mac OS environment, the isxdigit() function
216        is implemented as a macro that evaluates to its argument more than once,
217        contravening the C 90 Standard (I haven't checked a later standard). There
218        was an instance in pcretest which caused it to go wrong when processing
219        \x{...} escapes in subject strings. The has been rewritten to avoid using
220        things like p++ in the argument of isxdigit().
223    Version 8.13 16-Aug-2011
224    ------------------------
226    1.  The Unicode data tables have been updated to Unicode 6.0.0.
228    2.  Two minor typos in pcre_internal.h have been fixed.
230    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
231        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
232        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
234    4.  There were a number of related bugs in the code for matching backrefences
235        caselessly in UTF-8 mode when codes for the characters concerned were
236        different numbers of bytes. For example, U+023A and U+2C65 are an upper
237        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
238        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
239        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
240        2-byte code at the end of the subject (it thought there wasn't enough data
241        left).
243    5.  Comprehensive information about what went wrong is now returned by
244        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
245        as the output vector has at least 2 elements. The offset of the start of
246        the failing character and a reason code are placed in the vector.
248    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
249        now returned is for the first byte of the failing character, instead of the
250        last byte inspected. This is an incompatible change, but I hope it is small
251        enough not to be a problem. It makes the returned offset consistent with
252        pcre_exec() and pcre_dfa_exec().
254    7.  pcretest now gives a text phrase as well as the error number when
255        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
256        failure, the offset and reason code are output.
258    8.  When \R was used with a maximizing quantifier it failed to skip backwards
259        over a \r\n pair if the subsequent match failed. Instead, it just skipped
260        back over a single character (\n). This seems wrong (because it treated the
261        two characters as a single entity when going forwards), conflicts with the
262        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
263        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
264        has been changed.
266    9.  Some internal refactoring has changed the processing so that the handling
267        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
268        time (the PCRE_DOTALL option was changed this way some time ago: version
269        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
270        which was always a bit of a fudge. It also means that there is one less
271        argument for the match() function, which reduces its stack requirements
272        slightly. This change also fixes an incompatibility with Perl: the pattern
273        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
275    10. More internal refactoring has drastically reduced the number of recursive
276        calls to match() for possessively repeated groups such as (abc)++ when
277        using pcre_exec().
279    11. While implementing 10, a number of bugs in the handling of groups were
280        discovered and fixed:
282        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
283        (a|)*(?1) gave a compile-time internal error.
284        ((a|)+)+  did not notice that the outer group could match an empty string.
285        (^a|^)+   was not marked as anchored.
286        (.*a|.*)+ was not marked as matching at start or after a newline.
288    12. Yet more internal refactoring has removed another argument from the match()
289        function. Special calls to this function are now indicated by setting a
290        value in a variable in the "match data" data block.
292    13. Be more explicit in pcre_study() instead of relying on "default" for
293        opcodes that mean there is no starting character; this means that when new
294        ones are added and accidentally left out of pcre_study(), testing should
295        pick them up.
297    14. The -s option of pcretest has been documented for ages as being an old
298        synonym of -m (show memory usage). I have changed it to mean "force study
299        for every regex", that is, assume /S for every regex. This is similar to -i
300        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
301        using it. It makes it easier to run collections of tests with and without
302        study enabled, and thereby test pcre_study() more easily. All the standard
303        tests are now run with and without -s (but some patterns can be marked as
304        "never study" - see 20 below).
306    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
307        restoration of the capturing data to the outer values was not happening
308        correctly.
310    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
311        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
312        pattern had matched an empty string, and so incorrectly returned a no
313        match.
315    17. There was optimizing code for the last branch of non-capturing parentheses,
316        and also for the obeyed branch of a conditional subexpression, which used
317        tail recursion to cut down on stack usage. Unfortunately, now that there is
318        the possibility of (*THEN) occurring in these branches, tail recursion is
319        no longer possible because the return has to be checked for (*THEN). These
320        two optimizations have therefore been removed. [But see 8.20/11 above.]
322    18. If a pattern containing \R was studied, it was assumed that \R always
323        matched two bytes, thus causing the minimum subject length to be
324        incorrectly computed because \R can also match just one byte.
326    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
327        was incorrectly computed.
329    20. If /S is present twice on a test pattern in pcretest input, it now
330        *disables* studying, thereby overriding the use of -s on the command line
331        (see 14 above). This is necessary for one or two tests to keep the output
332        identical in both cases.
334    21. When (*ACCEPT) was used in an assertion that matched an empty string and
335        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
337    22. When an atomic group that contained a capturing parenthesis was
338        successfully matched, but the branch in which it appeared failed, the
339        capturing was not being forgotten if a higher numbered group was later
340        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
341        group 1 to "a", when in fact it should be unset. This applied to multi-
342        branched capturing and non-capturing groups, repeated or not, and also to
343        positive assertions (capturing in negative assertions does not happen
344        in PCRE) and also to nested atomic groups.
346    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
347        subject after a captured substring, to make it easier to tell which of a
348        number of identical substrings has been captured.
350    24. The way atomic groups are processed by pcre_exec() has been changed so that
351        if they are repeated, backtracking one repetition now resets captured
352        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
353        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
354        "aaa". Previously, it would have been "a". As part of this code
355        refactoring, the way recursive calls are handled has also been changed.
357    25. If an assertion condition captured any substrings, they were not passed
358        back unless some other capturing happened later. For example, if
359        (?(?=(a))a) was matched against "a", no capturing was returned.
361    26. When studying a pattern that contained subroutine calls or assertions,
362        the code for finding the minimum length of a possible match was handling
363        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
364        group 1 called group 2 while simultaneously a separate group 2 called group
365        1). A stack overflow occurred in this case. I have fixed this by limiting
366        the recursion depth to 10.
368    27. Updated RunTest.bat in the distribution to the version supplied by Tom
369        Fortmann. This supports explicit test numbers on the command line, and has
370        argument validation and error reporting.
372    28. An instance of \X with an unlimited repeat could fail if at any point the
373        first character it looked at was a mark character.
375    29. Some minor code refactoring concerning Unicode properties and scripts
376        should reduce the stack requirement of match() slightly.
378    30. Added the '=' option to pcretest to check the setting of unused capturing
379        slots at the end of the pattern, which are documented as being -1, but are
380        not included in the return count.
382    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
383        compiled something random. Now it gives a compile-time error (as does
384        Perl).
386    32. A *MARK encountered during the processing of a positive assertion is now
387        recorded and passed back (compatible with Perl).
389    33. If --only-matching or --colour was set on a pcregrep call whose pattern
390        had alternative anchored branches, the search for a second match in a line
391        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
392        matched the line "0102" twice. The same bug affected patterns that started
393        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
394        twice.
396    34. Previously, PCRE did not allow quantification of assertions. However, Perl
397        does, and because of capturing effects, quantifying parenthesized
398        assertions may at times be useful. Quantifiers are now allowed for
399        parenthesized assertions.
401    35. A minor code tidy in pcre_compile() when checking options for \R usage.
403    36. \g was being checked for fancy things in a character class, when it should
404        just be a literal "g".
406    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
407        appearance of a nested POSIX class supersedes an apparent external class.
408        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
409        unescaped square brackets may also appear as part of class names. For
410        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
411        more like Perl. (But see 8.20/1 above.)
413    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
414        was because it thought it was \N{name}, which is not supported).
416    39. Add minix to OS list not supporting the -S option in pcretest.
418    40. PCRE tries to detect cases of infinite recursion at compile time, but it
419        cannot analyze patterns in sufficient detail to catch mutual recursions
420        such as ((?1))((?2)). There is now a runtime test that gives an error if a
421        subgroup is called recursively as a subpattern for a second time at the
422        same position in the subject string. In previous releases this might have
423        been caught by the recursion limit, or it might have run out of stack.
425    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
426        happen only once. PCRE was, however incorrectly giving a compile time error
427        "recursive call could loop indefinitely" because it cannot analyze the
428        pattern in sufficient detail. The compile time test no longer happens when
429        PCRE is compiling a conditional subpattern, but actual runaway loops are
430        now caught at runtime (see 40 above).
432    42. It seems that Perl allows any characters other than a closing parenthesis
433        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
434        has been changed to be the same.
436    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
437        as not to get warnings when autogen.sh is called. Also changed
438        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
440    44. To help people who use pcregrep to scan files containing exceedingly long
441        lines, the following changes have been made:
443        (a) The default value of the buffer size parameter has been increased from
444            8K to 20K. (The actual buffer used is three times this size.)
446        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
447            PCRE is built.
449        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
450            to be set at run time.
452        (d) Numerical values in pcregrep options can be followed by K or M, for
453            example --buffer-size=50K.
455        (e) If a line being scanned overflows pcregrep's buffer, an error is now
456            given and the return code is set to 2.
458    45. Add a pointer to the latest mark to the callout data block.
460    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
461        partial match of an empty string instead of no match. This was specific to
462        the use of ".".
464    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
465        complete match instead of a partial match. This bug was dependent on both
466        the PCRE_UTF8 and PCRE_DOTALL options being set.
468    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
469        starting byte set, because \b was not being ignored.
472    Version 8.12 15-Jan-2011
473    ------------------------
475    1.  Fixed some typos in the markup of the man pages, and wrote a script that
476        checks for such things as part of the documentation building process.
478    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
479        --match-limit and --recursion-limit options (added for 8.11). In
480        particular, this made one of the standard tests fail. (The integer value
481        went into the wrong half of a long int.)
483    3.  If the --colour option was given to pcregrep with -v (invert match), it
484        did strange things, either producing crazy output, or crashing. It should,
485        of course, ignore a request for colour when reporting lines that do not
486        match.
488    4.  Another pcregrep bug caused similar problems if --colour was specified with
489        -M (multiline) and the pattern match finished with a line ending.
491    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
492        matched in multiline mode, the following line was shown as part of the
493        match. This seems wrong, so I have changed it.
495    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
496        the check for further matches in the same line (so they could be coloured)
497        to overrun the end of the current line. If another match was found, it was
498        incorrectly shown (and then shown again when found in the next line).
500    7.  If pcregrep was compiled under Windows, there was a reference to the
501        function pcregrep_exit() before it was defined. I am assuming this was
502        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
503        reported by a user. I've moved the definition above the reference.
506    Version 8.11 10-Dec-2010
507    ------------------------
509    1.  (*THEN) was not working properly if there were untried alternatives prior
510        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
511        backtracked to try for "b" instead of moving to the next alternative branch
512        at the same level (in this case, to look for "c"). The Perl documentation
513        is clear that when (*THEN) is backtracked onto, it goes to the "next
514        alternative in the innermost enclosing group".
516    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
517        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
518        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
519        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
520        (*THEN).
522    3.  If \s appeared in a character class, it removed the VT character from
523        the class, even if it had been included by some previous item, for example
524        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
525        of \s, but is part of the POSIX "space" class.)
527    4.  A partial match never returns an empty string (because you can always
528        match an empty string at the end of the subject); however the checking for
529        an empty string was starting at the "start of match" point. This has been
530        changed to the "earliest inspected character" point, because the returned
531        data for a partial match starts at this character. This means that, for
532        example, /(?<=abc)def/ gives a partial match for the subject "abc"
533        (previously it gave "no match").
535    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
536        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
537        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
538        has an implication that the given string is incomplete (because a partial
539        match is preferred over a full match). For this reason, these items now
540        give a partial match in this situation. [Aside: previously, the one case
541        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
542        match rather than a full match, which was wrong by the old rules, but is
543        now correct.]
545    6.  There was a bug in the handling of #-introduced comments, recognized when
546        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
547        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
548        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
549        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
550        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
551        places in pcre_compile().
553    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
554        comments when looking ahead for named forward references to subpatterns,
555        the only newline sequence it recognized was NL. It now handles newlines
556        according to the set newline convention.
558    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
559        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
560        cater for a lack of strerror(). These oversights have been fixed.
562    9.  Added --match-limit and --recursion-limit to pcregrep.
564    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
566    11. When the -o option was used, pcregrep was setting a return code of 1, even
567        when matches were found, and --line-buffered was not being honoured.
569    12. Added an optional parentheses number to the -o and --only-matching options
570        of pcregrep.
572    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
573        can match an empty string. The code to do it in pcretest and pcredemo
574        needed fixing:
576        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
577            only one byte after an empty string match just before CRLF (this case
578            just got forgotten; "any" and "anycrlf" were OK).
580        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
581            mode when an empty string match preceded an ASCII character followed by
582            a non-ASCII character. (The code for advancing by one character rather
583            than one byte was nonsense.)
585        (c) The pcredemo.c sample program did not have any code at all to handle
586            the cases when CRLF is a valid newline sequence.
588    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
589        as a starting offset was within the subject string. There is now a new
590        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
591        negative or greater than the length of the string. In order to test this,
592        pcretest is extended to allow the setting of negative starting offsets.
594    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
595        starting offset points to the beginning of a UTF-8 character was
596        unnecessarily clumsy. I tidied it up.
598    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
599        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
601    17. Nobody had reported that the --include_dir option, which was added in
602        release 7.7 should have been called --include-dir (hyphen, not underscore)
603        for compatibility with GNU grep. I have changed it to --include-dir, but
604        left --include_dir as an undocumented synonym, and the same for
605        --exclude-dir, though that is not available in GNU grep, at least as of
606        release 2.5.4.
608    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
609        characters from a string of bytes) have been redefined so as not to use
610        loops, in order to improve performance in some environments. At the same
611        time, I abstracted some of the common code into auxiliary macros to save
612        repetition (this should not affect the compiled code).
614    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
615        compile-time error is now given if \c is not followed by an ASCII
616        character, that is, a byte less than 128. (In EBCDIC mode, the code is
617        different, and any byte value is allowed.)
619    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
620        START_OPTIMIZE option, which is now allowed at compile time - but just
621        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
622        to pcregrep and other applications that have no direct access to PCRE
623        options. The new /Y option in pcretest sets this option when calling
624        pcre_compile().
626    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
627        back references. Groups containing recursive back references were forced to
628        be atomic by that change, but in the case of named groups, the amount of
629        memory required was incorrectly computed, leading to "Failed: internal
630        error: code overflow". This has been fixed.
632    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
633        pcretest.c, to avoid build problems in some Borland environments.
636    Version 8.10 25-Jun-2010
637    ------------------------
639    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
640        THEN.
642    2.  (*ACCEPT) was not working when inside an atomic group.
644    3.  Inside a character class, \B is treated as a literal by default, but
645        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
646        causes the error). The code is unchanged, but I tidied the documentation.
648    4.  Inside a character class, PCRE always treated \R and \X as literals,
649        whereas Perl faults them if its -w option is set. I have changed PCRE so
650        that it faults them when PCRE_EXTRA is set.
652    5.  Added support for \N, which always matches any character other than
653        newline. (It is the same as "." when PCRE_DOTALL is not set.)
655    6.  When compiling pcregrep with newer versions of gcc which may have
656        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
657        declared with attribute warn_unused_result" were given. Just casting the
658        result to (void) does not stop the warnings; a more elaborate fudge is
659        needed. I've used a macro to implement this.
661    7.  Minor change to pcretest.c to avoid a compiler warning.
663    8.  Added four artifical Unicode properties to help with an option to make
664        \s etc use properties (see next item). The new properties are: Xan
665        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
667    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
668        use Unicode properties. (*UCP) at the start of a pattern can be used to set
669        this option. Modified pcretest to add /W to test this facility. Added
670        REG_UCP to make it available via the POSIX interface.
672    10. Added --line-buffered to pcregrep.
674    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
675        studied, and the match started with a letter with a code point greater than
676        127 whose first byte was different to the first byte of the other case of
677        the letter, the other case of this starting letter was not recognized
678        (#976).
680    12. If a pattern that was studied started with a repeated Unicode property
681        test, for example, \p{Nd}+, there was the theoretical possibility of
682        setting up an incorrect bitmap of starting bytes, but fortunately it could
683        not have actually happened in practice until change 8 above was made (it
684        added property types that matched character-matching opcodes).
686    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
687        possible starting bytes for non-anchored patterns.
689    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
690        \R, and also a number of cases that involve Unicode properties, both
691        explicit and implicit when PCRE_UCP is set.
693    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
694        input, it could crash or give wrong results if characters with values
695        greater than 0xc0 were present in the subject string. (Detail: it assumed
696        UTF-8 input when processing these items.)
698    16. Added a lot of (int) casts to avoid compiler warnings in systems where
699        size_t is 64-bit (#991).
701    17. Added a check for running out of memory when PCRE is compiled with
702        --disable-stack-for-recursion (#990).
704    18. If the last data line in a file for pcretest does not have a newline on
705        the end, a newline was missing in the output.
707    19. The default pcre_chartables.c file recognizes only ASCII characters (values
708        less than 128) in its various bitmaps. However, there is a facility for
709        generating tables according to the current locale when PCRE is compiled. It
710        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
711        characters, are recognized by isspace() and therefore were getting set in
712        these tables, and indeed these tables seem to approximate to ISO 8859. This
713        caused a problem in UTF-8 mode when pcre_study() was used to create a list
714        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
715        which of course cannot start UTF-8 characters. I have changed the code so
716        that only real ASCII characters (less than 128) and the correct starting
717        bytes for UTF-8 encodings are set for characters greater than 127 when in
718        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
719        altogether.)
721    20. Added the /T option to pcretest so as to be able to run tests with non-
722        standard character tables, thus making it possible to include the tests
723        used for 19 above in the standard set of tests.
725    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
726        reference to a subpattern the other side of a comment that contains an
727        opening parenthesis caused either an internal compiling error, or a
728        reference to the wrong subpattern.
731    Version 8.02 19-Mar-2010
732    ------------------------
734    1.  The Unicode data tables have been updated to Unicode 5.2.0.
736    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
737        configured.
739    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
740        original author of that file, following a query about its status.
742    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
743        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
745    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
746        quantifier applied to a forward-referencing subroutine call, could compile
747        incorrect code or give the error "internal error: previously-checked
748        referenced subpattern not found".
750    6.  Both MS Visual Studio and Symbian OS have problems with initializing
751        variables to point to external functions. For these systems, therefore,
752        pcre_malloc etc. are now initialized to local functions that call the
753        relevant global functions.
755    7.  There were two entries missing in the vectors called coptable and poptable
756        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
757        I've fixed the data, and added a kludgy way of testing at compile time that
758        the lengths are correct (equal to the number of opcodes).
760    8.  Following on from 7, I added a similar kludge to check the length of the
761        eint vector in pcreposix.c.
763    9.  Error texts for pcre_compile() are held as one long string to avoid too
764        much relocation at load time. To find a text, the string is searched,
765        counting zeros. There was no check for running off the end of the string,
766        which could happen if a new error number was added without updating the
767        string.
769    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
771    11. \K was not working if it appeared in an atomic group or in a group that
772        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
773        \K is "not well defined" if used in an assertion. PCRE now accepts it if
774        the assertion is positive, but not if it is negative.
776    12. Change 11 fortuitously reduced the size of the stack frame used in the
777        "match()" function of pcre_exec.c by one pointer. Forthcoming
778        implementation of support for (*MARK) will need an extra pointer on the
779        stack; I have reserved it now, so that the stack frame size does not
780        decrease.
782    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
783        item in branch that calls a recursion is a subroutine call - as in the
784        second branch in the above example - was incorrectly given the compile-
785        time error "recursive call could loop indefinitely" because pcre_compile()
786        was not correctly checking the subroutine for matching a non-empty string.
788    14. The checks for overrunning compiling workspace could trigger after an
789        overrun had occurred. This is a "should never occur" error, but it can be
790        triggered by pathological patterns such as hundreds of nested parentheses.
791        The checks now trigger 100 bytes before the end of the workspace.
793    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
796    Version 8.01 19-Jan-2010
797    ------------------------
799    1.  If a pattern contained a conditional subpattern with only one branch (in
800        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
801        computed the wrong minimum data length (which is of course zero for such
802        subpatterns). This could cause incorrect "no match" results.
804    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
805        the pattern is reset in the first branch, pcre_compile() failed with
806        "internal error: code overflow at offset...". This happened only when
807        the reset was to the original external option setting. (An optimization
808        abstracts leading options settings into an external setting, which was the
809        cause of this.)
811    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
812        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
813        assertion pattern did not match (meaning that the assertion was true), it
814        was incorrectly treated as false if the SKIP had been reached during the
815        matching. This also applied to assertions used as conditions.
817    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
818        assertion subpattern, including such a pattern used as a condition,
819        unpredictable results occurred, instead of the error return
822    5.  The C++ GlobalReplace function was not working like Perl for the special
823        situation when an empty string is matched. It now does the fancy magic
824        stuff that is necessary.
826    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
827        removed. (These were left over from very, very early versions of PCRE.)
829    7.  Some cosmetic changes to the code to make life easier when compiling it
830        as part of something else:
832        (a) Change DEBUG to PCRE_DEBUG.
834        (b) In pcre_compile(), rename the member of the "branch_chain" structure
835            called "current" as "current_branch", to prevent a collision with the
836            Linux macro when compiled as a kernel module.
838        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
839            prevent a collision with the Linux macro when compiled as a kernel
840            module.
842    8.  In pcre_compile() there are some checks for integer overflows that used to
843        cast potentially large values to (double). This has been changed to that
844        when building, a check for int64_t is made, and if it is found, it is used
845        instead, thus avoiding the use of floating point arithmetic. (There is no
846        other use of FP in PCRE.) If int64_t is not found, the fallback is to
847        double.
849    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
850        2005 (difference between two addresses compared to an unsigned value).
852    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
853        custom one, because of the following reported problem in Windows:
855          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
856              under Win32.
857          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
858              therefore missing the function definition.
859          - The compiler thus generates a "C" signature for the test function.
860          - The linker fails to find the "C" function.
861          - PCRE fails to configure if asked to do so against libbz2.
863    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
864        messages were output:
866          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
867          rerunning libtoolize, to keep the correct libtool macros in-tree.
868          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
870        I have done both of these things.
872    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
873        most of the time, it *can* run out if it is given a pattern that contains a
874        runaway infinite recursion. I updated the discussion in the pcrestack man
875        page.
877    13. Now that we have gone to the x.xx style of version numbers, the minor
878        version may start with zero. Using 08 or 09 is a bad idea because users
879        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
880        interpreted as invalid octal numbers. I've updated the previous comment in
881        configure.ac, and also added a check that gives an error if 08 or 09 are
882        used.
884    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
885        causing partial matching to fail when the end of the subject matched \W
886        in a UTF-8 pattern where \W was quantified with a minimum of 3.
888    15. There were some discrepancies between the declarations in pcre_internal.h
889        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
890        their definitions. The declarations used "const uschar *" and the
891        definitions used USPTR. Even though USPTR is normally defined as "const
892        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
893        reported that: "This difference in casting confuses some C++ compilers, for
894        example, SunCC recognizes above declarations as different functions and
895        generates broken code for hbpcre." I have changed the declarations to use
896        USPTR.
898    16. GNU libtool is named differently on some systems. The autogen.sh script now
899        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
900        (FreeBSD).
902    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
903        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
904        comment: "Figure out how to create a longlong from a string: strtoll and
905        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
906        instance, but it only takes 2 args instead of 3!"
908    18. A subtle bug concerned with back references has been fixed by a change of
909        specification, with a corresponding code fix. A pattern such as
910        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
911        refers, was giving matches when it shouldn't. For example, xa=xaaa would
912        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
913        same bug. Such groups have to be quantified to be useful, or contained
914        inside another quantified group. (If there's no repetition, the reference
915        can never match.) The problem arises because, having left the group and
916        moved on to the rest of the pattern, a later failure that backtracks into
917        the group uses the captured value from the final iteration of the group
918        rather than the correct earlier one. I have fixed this in PCRE by forcing
919        any group that contains a reference to itself to be an atomic group; that
920        is, there cannot be any backtracking into it once it has completed. This is
921        similar to recursive and subroutine calls.
924    Version 8.00 19-Oct-09
925    ----------------------
927    1.  The table for translating pcre_compile() error codes into POSIX error codes
928        was out-of-date, and there was no check on the pcre_compile() error code
929        being within the table. This could lead to an OK return being given in
930        error.
932    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
933        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
934        in a Windows environment.
936    3.  The pcregrep --count option prints the count for each file even when it is
937        zero, as does GNU grep. However, pcregrep was also printing all files when
938        --files-with-matches was added. Now, when both options are given, it prints
939        counts only for those files that have at least one match. (GNU grep just
940        prints the file name in this circumstance, but including the count seems
941        more useful - otherwise, why use --count?) Also ensured that the
942        combination -clh just lists non-zero counts, with no names.
944    4.  The long form of the pcregrep -F option was incorrectly implemented as
945        --fixed_strings instead of --fixed-strings. This is an incompatible change,
946        but it seems right to fix it, and I didn't think it was worth preserving
947        the old behaviour.
949    5.  The command line items --regex=pattern and --regexp=pattern were not
950        recognized by pcregrep, which required --regex pattern or --regexp pattern
951        (with a space rather than an '='). The man page documented the '=' forms,
952        which are compatible with GNU grep; these now work.
954    6.  No libpcreposix.pc file was created for pkg-config; there was just
955        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
957    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
958        when UCP support is not needed, by modifying the Python script that
959        generates it from Unicode data files. This should not matter if the module
960        is correctly used as a library, but I received one complaint about 50K of
961        unwanted data. My guess is that the person linked everything into his
962        program rather than using a library. Anyway, it does no harm.
964    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
965        was a minimum greater than 1 for a wide character in a possessive
966        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
967        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
968        character. Chaos in the form of incorrect output or a compiling loop could
969        result.
971    9.  The restrictions on what a pattern can contain when partial matching is
972        requested for pcre_exec() have been removed. All patterns can now be
973        partially matched by this function. In addition, if there are at least two
974        slots in the offset vector, the offset of the earliest inspected character
975        for the match and the offset of the end of the subject are set in them when
976        PCRE_ERROR_PARTIAL is returned.
978    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
979        synonymous with PCRE_PARTIAL, for backwards compatibility, and
980        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
981        and may be more useful for multi-segment matching.
983    11. Partial matching with pcre_exec() is now more intuitive. A partial match
984        used to be given if ever the end of the subject was reached; now it is
985        given only if matching could not proceed because another character was
986        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
987        string "Z", which now yields "no match" instead of "partial match". In the
988        case of pcre_dfa_exec(), "no match" is given if every matching path for the
989        final character ended with (*FAIL).
991    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
992        if the pattern had a "must contain" character that was already found in the
993        earlier partial match, unless partial matching was again requested. For
994        example, with the pattern /dog.(body)?/, the "must contain" character is
995        "g". If the first part-match was for the string "dog", restarting with
996        "sbody" failed. This bug has been fixed.
998    13. The string returned by pcre_dfa_exec() after a partial match has been
999        changed so that it starts at the first inspected character rather than the
1000        first character of the match. This makes a difference only if the pattern
1001        starts with a lookbehind assertion or \b or \B (\K is not supported by
1002        pcre_dfa_exec()). It's an incompatible change, but it makes the two
1003        matching functions compatible, and I think it's the right thing to do.
1005    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
1006        so that the demonstration program is easily available in environments where
1007        PCRE has not been installed from source.
1009    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
1010        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
1011        library.
1013    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
1014        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
1015        is not the first non-POSIX option to be added. Clearly some people find
1016        these options useful.
1018    17. If a caller to the POSIX matching function regexec() passes a non-zero
1019        value for nmatch with a NULL value for pmatch, the value of
1020        nmatch is forced to zero.
1022    18. RunGrepTest did not have a test for the availability of the -u option of
1023        the diff command, as RunTest does. It now checks in the same way as
1024        RunTest, and also checks for the -b option.
1026    19. If an odd number of negated classes containing just a single character
1027        interposed, within parentheses, between a forward reference to a named
1028        subpattern and the definition of the subpattern, compilation crashed with
1029        an internal error, complaining that it could not find the referenced
1030        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
1031        [The bug was that it was starting one character too far in when skipping
1032        over the character class, thus treating the ] as data rather than
1033        terminating the class. This meant it could skip too much.]
1035    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
1036        /g option in pcretest when the pattern contains \K, which makes it possible
1037        to have an empty string match not at the start, even when the pattern is
1038        anchored. Updated pcretest and pcredemo to use this option.
1040    21. If the maximum number of capturing subpatterns in a recursion was greater
1041        than the maximum at the outer level, the higher number was returned, but
1042        with unset values at the outer level. The correct (outer level) value is
1043        now given.
1045    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
1046        PCRE did not set those parentheses (unlike Perl). I have now found a way to
1047        make it do so. The string so far is captured, making this feature
1048        compatible with Perl.
1050    23. The tests have been re-organized, adding tests 11 and 12, to make it
1051        possible to check the Perl 5.10 features against Perl 5.10.
1053    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
1054        pattern matches a fixed length string. PCRE did not allow this; now it
1055        does. Neither allows recursion.
1057    25. I finally figured out how to implement a request to provide the minimum
1058        length of subject string that was needed in order to match a given pattern.
1059        (It was back references and recursion that I had previously got hung up
1060        on.) This code has now been added to pcre_study(); it finds a lower bound
1061        to the length of subject needed. It is not necessarily the greatest lower
1062        bound, but using it to avoid searching strings that are too short does give
1063        some useful speed-ups. The value is available to calling programs via
1064        pcre_fullinfo().
1066    26. While implementing 25, I discovered to my embarrassment that pcretest had
1067        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
1068        study optimizations had never been tested with that matching function.
1069        Oops. What is worse, even when it was passed study data, there was a bug in
1070        pcre_dfa_exec() that meant it never actually used it. Double oops. There
1071        were also very few tests of studied patterns with pcre_dfa_exec().
1073    27. If (?| is used to create subpatterns with duplicate numbers, they are now
1074        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
1075        on the other side of the coin, they are no longer allowed to have different
1076        names, because these cannot be distinguished in PCRE, and this has caused
1077        confusion. (This is a difference from Perl.)
1079    28. When duplicate subpattern names are present (necessarily with different
1080        numbers, as required by 27 above), and a test is made by name in a
1081        conditional pattern, either for a subpattern having been matched, or for
1082        recursion in such a pattern, all the associated numbered subpatterns are
1083        tested, and the overall condition is true if the condition is true for any
1084        one of them. This is the way Perl works, and is also more like the way
1085        testing by number works.
1088    Version 7.9 11-Apr-09
1089  ---------------------  ---------------------
1091   1. Applied Bob Rossi and Daniel G's patches to convert the build system to one  1.  When building with support for bzlib/zlib (pcregrep) and/or readline
1092      that is more "standard", making use of automake and other autotools. There      (pcretest), all targets were linked against these libraries. This included
1093        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
1094        libraries. This caused unwanted dependencies to be created. This problem
1095        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
1096        pcretest is linked with readline.
1098    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
1099        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
1100        moved outside it again, because FALSE and TRUE are already defined in AIX,
1101        but BOOL is not.
1103    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
1104        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
1106    4.  The pcregrep documentation said spaces were inserted as well as colons (or
1107        hyphens) following file names and line numbers when outputting matching
1108        lines. This is not true; no spaces are inserted. I have also clarified the
1109        wording for the --colour (or --color) option.
1111    5.  In pcregrep, when --colour was used with -o, the list of matching strings
1112        was not coloured; this is different to GNU grep, so I have changed it to be
1113        the same.
1115    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
1116        each matching line was coloured. Now it goes on to look for further matches
1117        of any of the test patterns, which is the same behaviour as GNU grep.
1119    7.  A pattern that could match an empty string could cause pcregrep to loop; it
1120        doesn't make sense to accept an empty string match in pcregrep, so I have
1121        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
1122        seems to be how GNU grep behaves.
1124    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
1125        start or after a newline", because the conditional assertion was not being
1126        correctly handled. The rule now is that both the assertion and what follows
1127        in the first alternative must satisfy the test.
1129    9.  If auto-callout was enabled in a pattern with a conditional group whose
1130        condition was an assertion, PCRE could crash during matching, both with
1131        pcre_exec() and pcre_dfa_exec().
1133    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
1134        used for matching.
1136    11. Unicode property support in character classes was not working for
1137        characters (bytes) greater than 127 when not in UTF-8 mode.
1139    12. Added the -M command line option to pcretest.
1141    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
1143    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
1145    16. Added comments and documentation about mis-use of no_arg in the C++
1146        wrapper.
1148    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
1149        from Martin Jerabek that uses macro names for all relevant character and
1150        string constants.
1152    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
1153        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
1154        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
1155        these, but not everybody uses configure.
1157    19. A conditional group that had only one branch was not being correctly
1158        recognized as an item that could match an empty string. This meant that an
1159        enclosing group might also not be so recognized, causing infinite looping
1160        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
1161        with the subject "ab", where knowledge that the repeated group can match
1162        nothing is needed in order to break the loop.
1164    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
1165        exec(), but without supplying a callout function, matching went wrong.
1167    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
1168        leak if the size of the offset vector was greater than 30. When the vector
1169        is smaller, the saved offsets during recursion go onto a local stack
1170        vector, but for larger vectors malloc() is used. It was failing to free
1171        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
1172        error, in fact).
1174    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
1175        heapframe that is used only when UTF-8 support is enabled. This caused no
1176        problem, but was untidy.
1178    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
1179        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
1180        included within another project.
1182    24. Steven Van Ingelgem's patches to add more options to the CMake support,
1183        slightly modified by me:
1185          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
1186              not building pcregrep.
1188          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
1189              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
1191    25. Forward references, both numeric and by name, in patterns that made use of
1192        duplicate group numbers, could behave incorrectly or give incorrect errors,
1193        because when scanning forward to find the reference group, PCRE was not
1194        taking into account the duplicate group numbers. A pattern such as
1195        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
1197    26. Changed a few more instances of "const unsigned char *" to USPTR, making
1198        the feature of a custom pointer more persuasive (as requested by a user).
1200    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
1201        pcretest.c, inside #ifndefs, because it seems they are sometimes already
1202        pre-defined.
1204    28. Added support for (*UTF8) at the start of a pattern.
1206    29. Arrange for flags added by the "release type" setting in CMake to be shown
1207        in the configuration summary.
1210    Version 7.8 05-Sep-08
1211    ---------------------
1213    1.  Replaced UCP searching code with optimized version as implemented for Ad
1214        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
1215        stage table and inline lookup instead of a function, giving speed ups of 2
1216        to 5 times on some simple patterns that I tested. Permission was given to
1217        distribute the MultiStage2.py script that generates the tables (it's not in
1218        the tarball, but is in the Subversion repository).
1220    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
1221        scripts.
1223    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
1224        a group with a zero qualifier. The result of the study could be incorrect,
1225        or the function might crash, depending on the pattern.
1227    4.  Caseless matching was not working for non-ASCII characters in back
1228        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
1229        It now works when Unicode Property Support is available.
1231    5.  In pcretest, an escape such as \x{de} in the data was always generating
1232        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
1233        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
1234        truncation.
1236    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
1238    7.  Added two (int) casts to pcregrep when printing the difference of two
1239        pointers, in case they are 64-bit values.
1241    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
1242        test 2 if it fails.
1244    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
1245        and a #define of that name to empty if it is not externally set. This is to
1246        allow users of MSVC to set it if necessary.
1248    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
1249        the convenience functions in the pcre_get.c source file.
1251    11. An option change at the start of a pattern that had top-level alternatives
1252        could cause overwriting and/or a crash. This command provoked a crash in
1253        some environments:
1255          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
1257        This potential security problem was recorded as CVE-2008-2371.
1259    12. For a pattern where the match had to start at the beginning or immediately
1260        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
1261        pcre_dfa_exec() could read past the end of the passed subject if there was
1262        no match. To help with detecting such bugs (e.g. with valgrind), I modified
1263        pcretest so that it places the subject at the end of its malloc-ed buffer.
1265    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
1266        exec() might read past the end of the data buffer in UTF-8 mode.
1268    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
1269        the data contained the byte 0x85 as part of a UTF-8 character within its
1270        first line. This applied both to normal and DFA matching.
1272    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
1273        /^[^d]*?$/8 failed to match "abc".
1275    16. Added a missing copyright notice to pcrecpp_internal.h.
1277    17. Make it more clear in the documentation that values returned from
1278        pcre_exec() in ovector are byte offsets, not character counts.
1280    18. Tidied a few places to stop certain compilers from issuing warnings.
1282    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
1283        supplied by Stefan Weber. I made a further small update for 7.8 because
1284        there is a change of source arrangements: the pcre_searchfuncs.c module is
1285        replaced by pcre_ucd.c.
1288    Version 7.7 07-May-08
1289    ---------------------
1291    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
1292        a string to a long long, pretend we don't even have a long long." This is
1293        done by checking for the strtoq, strtoll, and _strtoi64 functions.
1295    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
1296        pre-7.6 versions, which defined a global no_arg variable instead of putting
1297        it in the RE class. (See also #8 below.)
1299    3.  Remove a line of dead code, identified by coverity and reported by Nuno
1300        Lopes.
1302    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
1304        (1) The include/exclude patterns were being applied to the whole pathnames
1305            of files, instead of just to the final components.
1307        (2) If there was more than one level of directory, the subdirectories were
1308            skipped unless they satisfied the include/exclude conditions. This is
1309            inconsistent with GNU grep (and could even be seen as contrary to the
1310            pcregrep specification - which I improved to make it absolutely clear).
1311            The action now is always to scan all levels of directory, and just
1312            apply the include/exclude patterns to regular files.
1314    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
1315        --exclude_dir in the tests to avoid scanning .svn directories.
1317    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
1318        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
1319        doesn't support NULs in patterns.
1321    7.  Added some missing "const"s to declarations of static tables in
1322        pcre_compile.c and pcre_dfa_exec.c.
1324    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
1325        caused by fix #2  above. (Subsequently also a second patch to fix the
1326        first patch. And a third patch - this was a messy problem.)
1328    9.  Applied Craig's patch to remove the use of push_back().
1330    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
1331        matching function regexec().
1333    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
1334        which, however, unlike Perl's \g{...}, are subroutine calls, not back
1335        references. PCRE supports relative numbers with this syntax (I don't think
1336        Oniguruma does).
1338    12. Previously, a group with a zero repeat such as (...){0} was completely
1339        omitted from the compiled regex. However, this means that if the group
1340        was called as a subroutine from elsewhere in the pattern, things went wrong
1341        (an internal error was given). Such groups are now left in the compiled
1342        pattern, with a new opcode that causes them to be skipped at execution
1343        time.
1345    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
1346        to the way PCRE behaves:
1348        (a) A lone ] character is dis-allowed (Perl treats it as data).
1350        (b) A back reference to an unmatched subpattern matches an empty string
1351            (Perl fails the current match path).
1353        (c) A data ] in a character class must be notated as \] because if the
1354            first data character in a class is ], it defines an empty class. (In
1355            Perl it is not possible to have an empty class.) The empty class []
1356            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
1357            The negative empty class [^] matches any one character, independently
1358            of the DOTALL setting.
1360    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
1361        non-existent subpattern following a character class starting with ']' and
1362        containing () gave an internal compiling error instead of "reference to
1363        non-existent subpattern". Fortunately, when the pattern did exist, the
1364        compiled code was correct. (When scanning forwards to check for the
1365        existencd of the subpattern, it was treating the data ']' as terminating
1366        the class, so got the count wrong. When actually compiling, the reference
1367        was subsequently set up correctly.)
1369    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
1370        it was being rejected as not supported by pcre_dfa_exec(), even though
1371        other assertions are supported. I have made pcre_dfa_exec() support
1372        (*FAIL).
1374    16. The implementation of 13c above involved the invention of a new opcode,
1375        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
1376        cannot be changed at match time, I realized I could make a small
1377        improvement to matching performance by compiling OP_ALLANY instead of
1378        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
1379        on the OP_ANY path.
1381    17. Compiling pcretest on Windows with readline support failed without the
1382        following two fixes: (1) Make the unistd.h include conditional on
1383        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
1385    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
1386        ncurses library to be included for pcretest when ReadLine support is
1387        requested, but also to allow for it to be overridden. This patch came from
1388        Daniel Bergström.
1390    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
1391        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
1392        any errors with the current Unicode tables. Thanks to Peter Kankowski for
1393        spotting this.
1396    Version 7.6 28-Jan-08
1397    ---------------------
1399    1.  A character class containing a very large number of characters with
1400        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
1401        overflow.
1403    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
1404        HAVE_LONG_LONG is not defined.
1406    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
1407        bring them up to date and include new features. This patch includes:
1409        - Fixed PH's badly added libz and libbz2 support.
1410        - Fixed a problem with static linking.
1411        - Added pcredemo. [But later removed - see 7 below.]
1412        - Fixed dftables problem and added an option.
1413        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
1414            HAVE_LONG_LONG.
1415        - Added readline support for pcretest.
1416        - Added an listing of the option settings after cmake has run.
1418    4.  A user submitted a patch to Makefile that makes it easy to create
1419        "pcre.dll" under mingw when using Configure/Make. I added stuff to
1420        Makefile.am that cause it to include this special target, without
1421        affecting anything else. Note that the same mingw target plus all
1422        the other distribution libraries and programs are now supported
1423        when configuring with CMake (see 6 below) instead of with
1424        Configure/Make.
1426    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
1427        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
1428        exported in the Windows port". It has not yet been confirmed that the patch
1429        solves the problem, but it does no harm.
1431    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
1432        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
1433        with CMake, and also correct the comment about stack recursion.
1435    7.  Remove the automatic building of pcredemo from the ./configure system and
1436        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
1437        of a program that users should build themselves after PCRE is installed, so
1438        building it automatically is not really right. What is more, it gave
1439        trouble in some build environments.
1441    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
1444    Version 7.5 10-Jan-08
1445    ---------------------
1447    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
1448        values in parens when parsing an RE using the C++ wrapper."
1450    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
1451        Characters greater than 255 were excluded from the class instead of being
1452        included.
1454    3.  The same bug as (2) above applied to negated POSIX classes such as
1455        [:^space:].
1457    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
1458        defined or documented. It seems to have been a typo for PCRE_STATIC, so
1459        I have changed it.
1461    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
1462        first named subpattern) and a construct such as (?&a) would reference the
1463        first named subpattern whose name started with "a" (in other words, the
1464        length check was missing). Both these problems are fixed. "Subpattern name
1465        expected" is now given for (?&) (a zero-length name), and this patch also
1466        makes it give the same error for \k'' (previously it complained that that
1467        was a reference to a non-existent subpattern).
1469    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
1470        this is right because (?- can be followed by option settings as well as by
1471        digits. I have, however, made the messages clearer.
1473    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
1474        than the number used in the conditional) now cause a compile-time error.
1475        This is actually not compatible with Perl, which accepts such patterns, but
1476        treats the conditional as always being FALSE (as PCRE used to), but it
1477        seems to me that giving a diagnostic is better.
1479    8.  Change "alphameric" to the more common word "alphanumeric" in comments
1480        and messages.
1482    9.  Fix two occurrences of "backslash" in comments that should have been
1483        "backspace".
1485    10. Remove two redundant lines of code that can never be obeyed (their function
1486        was moved elsewhere).
1488    11. The program that makes PCRE's Unicode character property table had a bug
1489        which caused it to generate incorrect table entries for sequences of
1490        characters that have the same character type, but are in different scripts.
1491        It amalgamated them into a single range, with the script of the first of
1492        them. In other words, some characters were in the wrong script. There were
1493        thirteen such cases, affecting characters in the following ranges:
1495          U+002b0 - U+002c1
1496          U+0060c - U+0060d
1497          U+0061e - U+00612
1498          U+0064b - U+0065e
1499          U+0074d - U+0076d
1500          U+01800 - U+01805
1501          U+01d00 - U+01d77
1502          U+01d9b - U+01dbf
1503          U+0200b - U+0200f
1504          U+030fc - U+030fe
1505          U+03260 - U+0327f
1506          U+0fb46 - U+0fbb1
1507          U+10450 - U+1049d
1509    12. The -o option (show only the matching part of a line) for pcregrep was not
1510        compatible with GNU grep in that, if there was more than one match in a
1511        line, it showed only the first of them. It now behaves in the same way as
1512        GNU grep.
1514    13. If the -o and -v options were combined for pcregrep, it printed a blank
1515        line for every non-matching line. GNU grep prints nothing, and pcregrep now
1516        does the same. The return code can be used to tell if there were any
1517        non-matching lines.
1519    14. Added --file-offsets and --line-offsets to pcregrep.
1521    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
1522        infinitely looping recursion. The bug was that positive lookaheads were not
1523        being skipped when checking for a possible empty match (negative lookaheads
1524        and both kinds of lookbehind were skipped).
1526    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
1527        inclusion of <windows.h> to before rather than after the definition of
1528        INVALID_FILE_ATTRIBUTES (patch from David Byron).
1530    17. Specifying a possessive quantifier with a specific limit for a Unicode
1531        character property caused pcre_compile() to compile bad code, which led at
1532        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
1533        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
1534        caused the error; without that there was no problem.
1536    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
1538    19. Added --enable-pcretest-libreadline.
1540    20. In pcrecpp.cc, the variable 'count' was incremented twice in
1541        RE::GlobalReplace(). As a result, the number of replacements returned was
1542        double what it should be. I removed one of the increments, but Craig sent a
1543        later patch that removed the other one (the right fix) and added unit tests
1544        that check the return values (which was not done before).
1546    21. Several CMake things:
1548        (1) Arranged that, when cmake is used on Unix, the libraries end up with
1549            the names libpcre and libpcreposix, not just pcre and pcreposix.
1551        (2) The above change means that pcretest and pcregrep are now correctly
1552            linked with the newly-built libraries, not previously installed ones.
1556    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
1557        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
1558        UTF-8 newline character). The key issue is that the pattern starts .*;
1559        this means that the match must be either at the beginning, or after a
1560        newline. The bug was in the code for advancing after a failed match and
1561        checking that the new position followed a newline. It was not taking
1562        account of UTF-8 characters correctly.
1564    23. PCRE was behaving differently from Perl in the way it recognized POSIX
1565        character classes. PCRE was not treating the sequence [:...:] as a
1566        character class unless the ... were all letters. Perl, however, seems to
1567        allow any characters between [: and :], though of course it rejects as
1568        unknown any "names" that contain non-letters, because all the known class
1569        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
1570        for example, whereas PCRE did not - it did not recognize a POSIX character
1571        class. This seemed a bit dangerous, so the code has been changed to be
1572        closer to Perl. The behaviour is not identical to Perl, because PCRE will
1573        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
1574        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
1575        Perl does, and where it didn't before.
1577    24. Rewrite so as to remove the single use of %n from pcregrep because in some
1578        Windows environments %n is disabled by default.
1581    Version 7.4 21-Sep-07
1582    ---------------------
1584    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
1585        means that a class such as [\s] counted as "explicit reference to CR or
1586        LF". That isn't really right - the whole point of the change was to try to
1587        help when there was an actual mention of one of the two characters. So now
1588        the change happens only if \r or \n (or a literal CR or LF) character is
1589        encountered.
1591    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
1592        of both had grown to the point where there were only 3 bits left.
1593        Fortunately, there was spare space in the data structure, and so I have
1594        moved the internal flags into a new 16-bit field to free up more option
1595        bits.
1597    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
1598        but did not set the internal JCHANGED flag - either of these is enough to
1599        control the way the "get" function works - but the PCRE_INFO_JCHANGED
1600        facility is supposed to tell if (?J) was ever used, so now (?J) at the
1601        start sets both bits.
1603    4.  Added options (at build time, compile time, exec time) to change \R from
1604        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
1606    5.  doc/pcresyntax.html was missing from the distribution.
1608    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
1609        compatibility, even though it is no longer used.
1611    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
1612        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
1613        windows.h file is present (where different names are used). [This was
1614        reversed later after testing - see 16 below.]
1616    8.  Changed all #include <config.h> to #include "config.h". There were also
1617        some further <pcre.h> cases that I changed to "pcre.h".
1619    9.  When pcregrep was used with the --colour option, it missed the line ending
1620        sequence off the lines that it output.
1622    10. It was pointed out to me that arrays of string pointers cause lots of
1623        relocations when a shared library is dynamically loaded. A technique of
1624        using a single long string with a table of offsets can drastically reduce
1625        these. I have refactored PCRE in four places to do this. The result is
1626        dramatic:
1628          Originally:                          290
1629          After changing UCP table:            187
1630          After changing error message table:   43
1631          After changing table of "verbs"       36
1632          After changing table of Posix names   22
1634        Thanks to the folks working on Gregex for glib for this insight.
1636    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
1637        unicode-properties was also set.
1639    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
1641    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
1642        checked only for CRLF.
1644    14. Added casts to pcretest.c to avoid compiler warnings.
1646    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
1648    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
1649        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
1650        entirely. This removes changes made in 7 above.
1652    17. The CMake files have been updated, and there is now more information about
1653        building with CMake in the NON-UNIX-USE document.
1656    Version 7.3 28-Aug-07
1657    ---------------------
1659     1. In the rejigging of the build system that eventually resulted in 7.1, the
1660        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
1661        brackets there is not right, since it causes compilers to look for an
1662        installed pcre.h, not the version that is in the source that is being
1663        compiled (which of course may be different). I have changed it back to:
1665          #include "pcre.h"
1667        I have a vague recollection that the change was concerned with compiling in
1668        different directories, but in the new build system, that is taken care of
1669        by the VPATH setting the Makefile.
1671     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
1672        when the subject happened to end in the byte 0x85 (e.g. if the last
1673        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
1674        characters but of course it shouldn't be taken as a newline when it is part
1675        of another character. The bug was that, for an unlimited repeat of . in
1676        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
1677        characters when looking for a newline.
1679     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
1681     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
1682        in debug output.
1684     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
1685        long printing in the pcrecpp unittest when running under MinGW.
1687     6. ESC_K was left out of the EBCDIC table.
1689     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
1690        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
1691        limit also applies to "virtual nesting" when a pattern is recursive, and in
1692        this case 1000 isn't so big. I have been able to remove this limit at the
1693        expense of backing off one optimization in certain circumstances. Normally,
1694        when pcre_exec() would call its internal match() function recursively and
1695        immediately return the result unconditionally, it uses a "tail recursion"
1696        feature to save stack. However, when a subpattern that can match an empty
1697        string has an unlimited repetition quantifier, it no longer makes this
1698        optimization. That gives it a stack frame in which to save the data for
1699        checking that an empty string has been matched. Previously this was taken
1700        from the 1000-entry workspace that had been reserved. So now there is no
1701        explicit limit, but more stack is used.
1703     8. Applied Daniel's patches to solve problems with the import/export magic
1704        syntax that is required for Windows, and which was going wrong for the
1705        pcreposix and pcrecpp parts of the library. These were overlooked when this
1706        problem was solved for the main library.
1708     9. There were some crude static tests to avoid integer overflow when computing
1709        the size of patterns that contain repeated groups with explicit upper
1710        limits. As the maximum quantifier is 65535, the maximum group length was
1711        set at 30,000 so that the product of these two numbers did not overflow a
1712        32-bit integer. However, it turns out that people want to use groups that
1713        are longer than 30,000 bytes (though not repeat them that many times).
1714        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
1715        made it possible to implement the integer overflow checks in a much more
1716        dynamic way, which I have now done. The artificial limitation on group
1717        length has been removed - we now have only the limit on the total length of
1718        the compiled pattern, which depends on the LINK_SIZE setting.
1720    10. Fixed a bug in the documentation for get/copy named substring when
1721        duplicate names are permitted. If none of the named substrings are set, the
1722        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
1723        empty string.
1725    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
1726        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
1727        because the ] is interpreted as the first data character and the
1728        terminating ] is not found. PCRE has been made compatible with Perl in this
1729        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
1730        cause memory overwriting.
1732    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
1733        string has been matched (to stop an infinite loop). It was not recognizing
1734        a conditional subpattern that could match an empty string if that
1735        subpattern was within another subpattern. For example, it looped when
1736        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
1737        condition was not nested. This bug has been fixed.
1739    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
1740        past the start of the subject in the presence of bytes with the top bit
1741        set, for example "\x8aBCD".
1743    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
1744        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
1746    14. Optimized (?!) to (*FAIL).
1748    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
1749        This restricts code points to be within the range 0 to 0x10FFFF, excluding
1750        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
1751        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
1752        does: it's just the validity check that is more restrictive.
1754    16. Inserted checks for integer overflows during escape sequence (backslash)
1755        processing, and also fixed erroneous offset values for syntax errors during
1756        backslash processing.
1758    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
1759        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
1761    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
1762        caused an overrun.
1764    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
1765        something other than just ASCII characters) inside a group that had an
1766        unlimited repeat caused a loop at compile time (while checking to see
1767        whether the group could match an empty string).
1769    20. Debugging a pattern containing \p or \P could cause a crash. For example,
1770        [\P{Any}] did so. (Error in the code for printing property names.)
1772    21. An orphan \E inside a character class could cause a crash.
1774    22. A repeated capturing bracket such as (A)? could cause a wild memory
1775        reference during compilation.
1777    23. There are several functions in pcre_compile() that scan along a compiled
1778        expression for various reasons (e.g. to see if it's fixed length for look
1779        behind). There were bugs in these functions when a repeated \p or \P was
1780        present in the pattern. These operators have additional parameters compared
1781        with \d, etc, and these were not being taken into account when moving along
1782        the compiled data. Specifically:
1784        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
1785            length.
1787        (b) An item such as \pL+ within a repeated group could cause crashes or
1788            loops.
1790        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
1791            "reference to non-existent subpattern" error.
1793        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
1795    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
1796        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
1798    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
1800    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
1801        character were causing crashes (broken optimization).
1803    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
1804        \p or \P) caused a compile-time loop.
1806    28. More problems have arisen in unanchored patterns when CRLF is a valid line
1807        break. For example, the unstudied pattern [\r\n]A does not match the string
1808        "\r\nA" because change 7.0/46 below moves the current point on by two
1809        characters after failing to match at the start. However, the pattern \nA
1810        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
1811        the same is true. There doesn't seem any very clean way out of this, but
1812        what I have chosen to do makes the common cases work: PCRE now takes note
1813        of whether there can be an explicit match for \r or \n anywhere in the
1814        pattern, and if so, 7.0/46 no longer applies. As part of this change,
1815        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
1816        pattern has explicit CR or LF references.
1818    29. Added (*CR) etc for changing newline setting at start of pattern.
1821    Version 7.2 19-Jun-07
1822    ---------------------
1824     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
1825        which is apparently normally available under Windows.
1827     2. Re-jig the pcregrep tests with different newline settings in an attempt
1828        to make them independent of the local environment's newline setting.
1830     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
1832     4. Some of the "internals" tests were previously cut out when the link size
1833        was not 2, because the output contained actual offsets. The recent new
1834        "Z" feature of pcretest means that these can be cut out, making the tests
1835        usable with all link sizes.
1837     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
1838        stack recursion. This gives a massive performance boost under BSD, but just
1839        a small improvement under Linux. However, it saves one field in the frame
1840        in all cases.
1842     6. Added more features from the forthcoming Perl 5.10:
1844        (a) (?-n) (where n is a string of digits) is a relative subroutine or
1845            recursion call. It refers to the nth most recently opened parentheses.
1847        (b) (?+n) is also a relative subroutine call; it refers to the nth next
1848            to be opened parentheses.
1850        (c) Conditions that refer to capturing parentheses can be specified
1851            relatively, for example, (?(-2)... or (?(+3)...
1853        (d) \K resets the start of the current match so that everything before
1854            is not part of it.
1856        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
1858        (f) \g{name} is another synonym - part of Perl 5.10's unification of
1859            reference syntax.
1861        (g) (?| introduces a group in which the numbering of parentheses in each
1862            alternative starts with the same number.
1864        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
1866     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
1869     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
1870        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
1871        for detecting groups that can match an empty string.
1873     9. A pattern with a very large number of alternatives (more than several
1874        hundred) was running out of internal workspace during the pre-compile
1875        phase, where pcre_compile() figures out how much memory will be needed. A
1876        bit of new cunning has reduced the workspace needed for groups with
1877        alternatives. The 1000-alternative test pattern now uses 12 bytes of
1878        workspace instead of running out of the 4096 that are available.
1880    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
1882    11. Applied patch from Google to remove an optimization that didn't quite work.
1883        The report of the bug said:
1885          pcrecpp::RE("a*").FullMatch("aaa") matches, while
1886          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
1887          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
1889    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
1890        it matched the wrong number of bytes.
1893    Version 7.1 24-Apr-07
1894    ---------------------
1896     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
1897        that is more "standard", making use of automake and other Autotools. There
1898      is some re-arrangement of the files and adjustment of comments consequent      is some re-arrangement of the files and adjustment of comments consequent
1899      on this.      on this.
1901   2. Part of the patch fixed a problem with the pcregrep tests. The test of -r   2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
1902      for recursive directory scanning broke on some systems because the files      for recursive directory scanning broke on some systems because the files
1903      are not scanned in any specific order and on different systems the order      are not scanned in any specific order and on different systems the order
1904      was different. A call to "sort" has been inserted into RunGrepTest for the      was different. A call to "sort" has been inserted into RunGrepTest for the
1905      approprate test as a short-term fix. In the longer term there may be an      approprate test as a short-term fix. In the longer term there may be an
1906      alternative.      alternative.
1908   3. I had an email from Eric Raymond about problems translating some of PCRE's   3. I had an email from Eric Raymond about problems translating some of PCRE's
1909      man pages to HTML (despite the fact that I distribute HTML pages, some      man pages to HTML (despite the fact that I distribute HTML pages, some
1910      people do their own conversions for various reasons). The problems      people do their own conversions for various reasons). The problems
1911      concerned the use of low-level troff macros .br and .in. I have therefore      concerned the use of low-level troff macros .br and .in. I have therefore
1912      removed all such uses from the man pages (some were redundant, some could      removed all such uses from the man pages (some were redundant, some could
1913      be replaced by .nf/.fi pairs). The maintain/132html script that I use to      be replaced by .nf/.fi pairs). The 132html script that I use to generate
1914      generate HTML has been updated to handle .nf/.fi and to complain if it      HTML has been updated to handle .nf/.fi and to complain if it encounters
1915      encounters .br or .in.      .br or .in.
1917   4. Updated comments in configure.ac that get placed in config.h.in and also   4. Updated comments in configure.ac that get placed in config.h.in and also
1918      arranged for config.h to be included in the distribution, for the benefit      arranged for config.h to be included in the distribution, with the name
1919      of those who have to compile without Autotools (compare pcre.h).      config.h.generic, for the benefit of those who have to compile without
1920        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
1921   5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan  
1922      Weber: (1) pcre_internal.h was missing some function renames; (2) updated   5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
1923      makevp.bat for the current PCRE, using the additional files !compile.txt,      Weber: (1) pcre_internal.h was missing some function renames; (2) updated
1924      !linklib.txt, and pcregexp.pas.      makevp.bat for the current PCRE, using the additional files
1925        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
1927     6. A Windows user reported a minor discrepancy with test 2, which turned out
1928        to be caused by a trailing space on an input line that had got lost in his
1929        copy. The trailing space was an accident, so I've just removed it.
1931     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
1932        that is needed.
1934     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
1935        as "const" (a) because they are and (b) because it helps the PHP
1936        maintainers who have recently made a script to detect big data structures
1937        in the php code that should be moved to the .rodata section. I remembered
1938        to update Builducptable as well, so it won't revert if ucptable.h is ever
1939        re-created.
1941     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
1942        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
1943        order to be able to cut out the UTF-8 tables in the latter when UTF-8
1944        support is not required. This saves 1.5-2K of code, which is important in
1945        some applications.
1947        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
1948        so as not to refer to the tables, even though these functions will never be
1949        called when UTF-8 support is disabled. Otherwise there are problems with a
1950        shared library.
1952    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
1954        (a) It was defining its arguments as char * instead of void *.
1956        (b) It was assuming that all moves were upwards in memory; this was true
1957            a long time ago when I wrote it, but is no longer the case.
1959        The emulated memove() is provided for those environments that have neither
1960        memmove() nor bcopy(). I didn't think anyone used it these days, but that
1961        is clearly not the case, as these two bugs were recently reported.
1963    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
1964        and Detrail to create the HTML documentation, the .txt form of the man
1965        pages, and it removes trailing spaces from listed files. It also creates
1966        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
1967        case, it wraps all the #defines with #ifndefs. This script should be run
1968        before "make dist".
1970    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
1971        with Unicode property support.
1973        (a) For a maximizing quantifier, if the two different cases of the
1974            character were of different lengths in their UTF-8 codings (there are
1975            some cases like this - I found 11), and the matching function had to
1976            back up over a mixture of the two cases, it incorrectly assumed they
1977            were both the same length.
1979        (b) When PCRE was configured to use the heap rather than the stack for
1980            recursion during matching, it was not correctly preserving the data for
1981            the other case of a UTF-8 character when checking ahead for a match
1982            while processing a minimizing repeat. If the check also involved
1983            matching a wide character, but failed, corruption could cause an
1984            erroneous result when trying to check for a repeat of the original
1985            character.
1987    13. Some tidying changes to the testing mechanism:
1989        (a) The RunTest script now detects the internal link size and whether there
1990            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
1991            values substituted by "configure". (The RunGrepTest script already did
1992            this for UTF-8.) The configure.ac script no longer substitutes the
1993            relevant variables.
1995        (b) The debugging options /B and /D in pcretest show the compiled bytecode
1996            with length and offset values. This means that the output is different
1997            for different internal link sizes. Test 2 is skipped for link sizes
1998            other than 2 because of this, bypassing the problem. Unfortunately,
1999            there was also a test in test 3 (the locale tests) that used /B and
2000            failed for link sizes other than 2. Rather than cut the whole test out,
2001            I have added a new /Z option to pcretest that replaces the length and
2002            offset values with spaces. This is now used to make test 3 independent
2003            of link size. (Test 2 will be tidied up later.)
2005    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
2006        segmentation fault instead of returning the appropriate error message.
2008    15. In multiline mode when the newline sequence was set to "any", the pattern
2009        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
2010        This doesn't seem right; it now treats the CRLF combination as the line
2011        ending, and so does not match in that case. It's only a pattern such as ^$
2012        that would hit this one: something like ^ABC$ would have failed after \r
2013        and then tried again after \r\n.
2015    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
2016        in an attempt to make files that differ only in their line terminators
2017        compare equal. This works on Linux.
2019    17. Under certain error circumstances pcregrep might try to free random memory
2020        as it exited. This is now fixed, thanks to valgrind.
2022    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
2023        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
2024        was because its rules for how to advance for /g after matching an empty
2025        string at the end of a line did not allow for this case. They now check for
2026        it specially.
2028    20. pcretest is supposed to handle patterns and data of any length, by
2029        extending its buffers when necessary. It was getting this wrong when the
2030        buffer for a data line had to be extended.
2032    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
2033        CRLF as a newline sequence.
2035    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
2036        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
2037        I have nevertheless tidied it up.
2039    23. Added some casts to kill warnings from HP-UX ia64 compiler.
2041    24. Added a man page for pcre-config.
2044  Version 7.0 19-Dec-06  Version 7.0 19-Dec-06
2045  ---------------------  ---------------------

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