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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.1 05-Mar-07
5    ---------------------
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other autotools. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
12     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
13        for recursive directory scanning broke on some systems because the files
14        are not scanned in any specific order and on different systems the order
15        was different. A call to "sort" has been inserted into RunGrepTest for the
16        approprate test as a short-term fix. In the longer term there may be an
17        alternative.
19     3. I had an email from Eric Raymond about problems translating some of PCRE's
20        man pages to HTML (despite the fact that I distribute HTML pages, some
21        people do their own conversions for various reasons). The problems
22        concerned the use of low-level troff macros .br and .in. I have therefore
23        removed all such uses from the man pages (some were redundant, some could
24        be replaced by .nf/.fi pairs). The 132html script that I use to generate
25        HTML has been updated to handle .nf/.fi and to complain if it encounters
26        .br or .in.
28     4. Updated comments in configure.ac that get placed in config.h.in and also
29        arranged for config.h to be included in the distribution, with the name
30        config.h.generic, for the benefit of those who have to compile without
31        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
33     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
34        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
35        makevp.bat for the current PCRE, using the additional files !compile.txt,
36        !linklib.txt, and pcregexp.pas.
38     6. A Windows user reported a minor discrepancy with test 2, which turned out
39        to be caused by a trailing space on an input line that had got lost in his
40        copy. The trailing space was an accident, so I've just removed it.
42     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
43        that is needed.
45     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
46        as "const" (a) because they are and (b) because it helps the PHP
47        maintainers who have recently made a script to detect big data structures
48        in the php code that should be moved to the .rodata section. I remembered
49        to update Builducptable as well, so it won't revert if ucptable.h is ever
50        re-created.
52     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
53        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
54        order to be able to cut out the UTF-8 tables in the latter when UTF-8
55        support is not required. This saves 1.5-2K of code, which is important in
56        some applications.
58        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
59        so as not to refer to the tables, even though these functions will never be
60        called when UTF-8 support is disabled. Otherwise there are problems with a
61        shared library.
63    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
65        (a) It was defining its arguments as char * instead of void *.
67        (b) It was assuming that all moves were upwards in memory; this was true
68            a long time ago when I wrote it, but is no longer the case.
70        The emulated memove() is provided for those environments that have neither
71        memmove() nor bcopy(). I didn't think anyone used it these days, but that
72        is clearly not the case, as these two bugs were recently reported.
74    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
75        and Detrail to create the HTML documentation, the .txt form of the man
76        pages, and it removes trailing spaces from listed files. It also creates
77        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
78        case, it wraps all the #defines with #ifndefs. This script should be run
79        before "make dist".
81    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
82        with Unicode property support.
84        (a) For a maximizing quantifier, if the two different cases of the
85            character were of different lengths in their UTF-8 codings (there are
86            some cases like this - I found 11), and the matching function had to
87            back up over a mixture of the two cases, it incorrectly assumed they
88            were both the same length.
90        (b) When PCRE was configured to use the heap rather than the stack for
91            recursion during matching, it was not correctly preserving the data for
92            the other case of a UTF-8 character when checking ahead for a match
93            while processing a minimizing repeat. If the check also involved
94            matching a wide character, but failed, corruption could cause an
95            erroneous result when trying to check for a repeat of the original
96            character.
98    13. Some tidying changes to the testing mechanism:
100        (a) The RunTest script now detects the internal link size and whether there
101            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
102            values substituted by "configure". (The RunGrepTest script already did
103            this for UTF-8.) The configure.ac script no longer substitutes the
104            relevant variables.
106        (b) The debugging options /B and /D in pcretest show the compiled bytecode
107            with length and offset values. This means that the output is different
108            for different internal link sizes. Test 2 is skipped for link sizes
109            other than 2 because of this, bypassing the problem. Unfortunately,
110            there was also a test in test 3 (the locale tests) that used /B and
111            failed for link sizes other than 2. Rather than cut the whole test out,
112            I have added a new /Z option to pcretest that replaces the length and
113            offset values with spaces. This is now used to make test 3 independent
114            of link size.
117    Version 7.0 19-Dec-06
118    ---------------------
120     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
121        moving to gcc 4.1.1.
123     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
124        sys/time.h, which is documented as needed for this function. It doesn't
125        seem to matter on Linux, but it showed up on some releases of OS X.
127     3. It seems that there are systems where bytes whose values are greater than
128        127 match isprint() in the "C" locale. The "C" locale should be the
129        default when a C program starts up. In most systems, only ASCII printing
130        characters match isprint(). This difference caused the output from pcretest
131        to vary, making some of the tests fail. I have changed pcretest so that:
133        (a) When it is outputting text in the compiled version of a pattern, bytes
134            other than 32-126 are always shown as hex escapes.
136        (b) When it is outputting text that is a matched part of a subject string,
137            it does the same, unless a different locale has been set for the match
138            (using the /L modifier). In this case, it uses isprint() to decide.
140     4. Fixed a major bug that caused incorrect computation of the amount of memory
141        required for a compiled pattern when options that changed within the
142        pattern affected the logic of the preliminary scan that determines the
143        length. The relevant options are -x, and -i in UTF-8 mode. The result was
144        that the computed length was too small. The symptoms of this bug were
145        either the PCRE error "internal error: code overflow" from pcre_compile(),
146        or a glibc crash with a message such as "pcretest: free(): invalid next
147        size (fast)". Examples of patterns that provoked this bug (shown in
148        pcretest format) are:
150          /(?-x: )/x
151          /(?x)(?-x: \s*#\s*)/
152          /((?i)[\x{c0}])/8
153          /(?i:[\x{c0}])/8
155        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
156        is now done differently.
158     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
159        wrapper classes; (b) implement a new function in the C++ scanner that is
160        more efficient than the old way of doing things because it avoids levels of
161        recursion in the regex matching; (c) add a paragraph to the documentation
162        for the FullMatch() function.
164     6. The escape sequence \n was being treated as whatever was defined as
165        "newline". Not only was this contrary to the documentation, which states
166        that \n is character 10 (hex 0A), but it also went horribly wrong when
167        "newline" was defined as CRLF. This has been fixed.
169     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
170        was being set to -1 for the "end of line" case (supposedly a value that no
171        character can have). Though this value is never used (the check for end of
172        line is "zero bytes in current character"), it caused compiler complaints.
173        I've changed it to 0xffffffff.
175     8. In pcre_version.c, the version string was being built by a sequence of
176        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
177        string (as it is for production releases) called a macro with an empty
178        argument. The C standard says the result of this is undefined. The gcc
179        compiler treats it as an empty string (which was what was wanted) but it is
180        reported that Visual C gives an error. The source has been hacked around to
181        avoid this problem.
183     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
184        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
185        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
186        of them did).
188    10. Originally, pcretest opened its input and output without "b"; then I was
189        told that "b" was needed in some environments, so it was added for release
190        5.0 to both the input and output. (It makes no difference on Unix-like
191        systems.) Later I was told that it is wrong for the input on Windows. I've
192        now abstracted the modes into two macros, to make it easier to fiddle with
193        them, and removed "b" from the input mode under Windows.
195    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
197    12. Added -help and --help to pcretest as an official way of being reminded
198        of the options.
200    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
201        and pcrecpp.cc because they annoy compilers at high warning levels.
203    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
205    15. Fixed an occurrence of == in configure.ac that should have been = (shell
206        scripts are not C programs :-) and which was not noticed because it works
207        on Linux.
209    16. pcretest is supposed to handle any length of pattern and data line (as one
210        line or as a continued sequence of lines) by extending its input buffer if
211        necessary. This feature was broken for very long pattern lines, leading to
212        a string of junk being passed to pcre_compile() if the pattern was longer
213        than about 50K.
215    17. I have done a major re-factoring of the way pcre_compile() computes the
216        amount of memory needed for a compiled pattern. Previously, there was code
217        that made a preliminary scan of the pattern in order to do this. That was
218        OK when PCRE was new, but as the facilities have expanded, it has become
219        harder and harder to keep it in step with the real compile phase, and there
220        have been a number of bugs (see for example, 4 above). I have now found a
221        cunning way of running the real compile function in a "fake" mode that
222        enables it to compute how much memory it would need, while actually only
223        ever using a few hundred bytes of working memory and without too many
224        tests of the mode. This should make future maintenance and development
225        easier. A side effect of this work is that the limit of 200 on the nesting
226        depth of parentheses has been removed (though this was never a serious
227        limitation, I suspect). However, there is a downside: pcre_compile() now
228        runs more slowly than before (30% or more, depending on the pattern). I
229        hope this isn't a big issue. There is no effect on runtime performance.
231    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
232        newline (only possible for the last line of a file) and it was a
233        pattern that set a locale (followed by /Lsomething), pcretest crashed.
235    19. Added additional timing features to pcretest. (1) The -tm option now times
236        matching only, not compiling. (2) Both -t and -tm can be followed, as a
237        separate command line item, by a number that specifies the number of
238        repeats to use when timing. The default is 50000; this gives better
239        precision, but takes uncomfortably long for very large patterns.
241    20. Extended pcre_study() to be more clever in cases where a branch of a
242        subpattern has no definite first character. For example, (a*|b*)[cd] would
243        previously give no result from pcre_study(). Now it recognizes that the
244        first character must be a, b, c, or d.
246    21. There was an incorrect error "recursive call could loop indefinitely" if
247        a subpattern (or the entire pattern) that was being tested for matching an
248        empty string contained only one non-empty item after a nested subpattern.
249        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
250        incorrectly, because the \d was being skipped in the check.
252    22. The pcretest program now has a new pattern option /B and a command line
253        option -b, which is equivalent to adding /B to every pattern. This causes
254        it to show the compiled bytecode, without the additional information that
255        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
256        is the same as /B/I).
258    23. A new optimization is now able automatically to treat some sequences such
259        as a*b as a*+b. More specifically, if something simple (such as a character
260        or a simple class like \d) has an unlimited quantifier, and is followed by
261        something that cannot possibly match the quantified thing, the quantifier
262        is automatically "possessified".
264    24. A recursive reference to a subpattern whose number was greater than 39
265        went wrong under certain circumstances in UTF-8 mode. This bug could also
266        have affected the operation of pcre_study().
268    25. Realized that a little bit of performance could be had by replacing
269        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
271    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
273    27. Possessive quantifiers such as a++ were previously implemented by turning
274        them into atomic groups such as ($>a+). Now they have their own opcodes,
275        which improves performance. This includes the automatically created ones
276        from 23 above.
278    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
279        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
280        the first matched character to be a colon. This applied both to named and
281        numbered groups.
283    29. The ucpinternal.h header file was missing its idempotency #ifdef.
285    30. I was sent a "project" file called libpcre.a.dev which I understand makes
286        building PCRE on Windows easier, so I have included it in the distribution.
288    31. There is now a check in pcretest against a ridiculously large number being
289        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
290        loop, the loop is abandoned.
292    32. Forward references to subpatterns in conditions such as (?(2)...) where
293        subpattern 2 is defined later cause pcre_compile() to search forwards in
294        the pattern for the relevant set of parentheses. This search went wrong
295        when there were unescaped parentheses in a character class, parentheses
296        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
298    33. "Subroutine" calls and backreferences were previously restricted to
299        referencing subpatterns earlier in the regex. This restriction has now
300        been removed.
302    34. Added a number of extra features that are going to be in Perl 5.10. On the
303        whole, these are just syntactic alternatives for features that PCRE had
304        previously implemented using the Python syntax or my own invention. The
305        other formats are all retained for compatibility.
307        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
308            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
309            also .NET compatible.
311        (b) A recursion or subroutine call to a named group can now be defined as
312            (?&name) as well as (?P>name).
314        (c) A backreference to a named group can now be defined as \k<name> or
315            \k'name' as well as (?P=name). The new forms, as well as being in Perl
316            5.10, are also .NET compatible.
318        (d) A conditional reference to a named group can now use the syntax
319            (?(<name>) or (?('name') as well as (?(name).
321        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
322            groups (named and numbered) that are never evaluated inline, but can be
323            called as "subroutines" from elsewhere. In effect, the DEFINE condition
324            is always false. There may be only one alternative in such a group.
326        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
327            as the simple (?(R). The condition is true only if the most recent
328            recursion is that of the given number or name. It does not search out
329            through the entire recursion stack.
331        (g) The escape \gN or \g{N} has been added, where N is a positive or
332            negative number, specifying an absolute or relative reference.
334    35. Tidied to get rid of some further signed/unsigned compiler warnings and
335        some "unreachable code" warnings.
337    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
338        things, this adds five new scripts.
340    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
341        There were also incompatibilities regarding the handling of \Q..\E inside
342        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
343        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
345    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
346        matches an empty string, and forcibly breaks the loop. There were bugs in
347        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
348        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
349        separate and independent bugs (that affected different cases) have been
350        fixed.
352    39. Refactored the code to abolish the use of different opcodes for small
353        capturing bracket numbers. This is a tidy that I avoided doing when I
354        removed the limit on the number of capturing brackets for 3.5 back in 2001.
355        The new approach is not only tidier, it makes it possible to reduce the
356        memory needed to fix the previous bug (38).
358    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
359        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
360        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
361        mode.
363    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
364        report.
366    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
367        copy construction and assignment in the C++ wrapper.
369    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
370        couple of bugs that could have given wrong results in the "--newline=crlf"
371        case.
373    44. Added a number of casts and did some reorganization of signed/unsigned int
374        variables following suggestions from Dair Grant. Also renamed the variable
375        "this" as "item" because it is a C++ keyword.
377    45. Arranged for dftables to add
379          #include "pcre_internal.h"
381        to pcre_chartables.c because without it, gcc 4.x may remove the array
382        definition from the final binary if PCRE is built into a static library and
383        dead code stripping is activated.
385    46. For an unanchored pattern, if a match attempt fails at the start of a
386        newline sequence, and the newline setting is CRLF or ANY, and the next two
387        characters are CRLF, advance by two characters instead of one.
390    Version 6.7 04-Jul-06
391    ---------------------
393     1. In order to handle tests when input lines are enormously long, pcretest has
394        been re-factored so that it automatically extends its buffers when
395        necessary. The code is crude, but this _is_ just a test program. The
396        default size has been increased from 32K to 50K.
398     2. The code in pcre_study() was using the value of the re argument before
399        testing it for NULL. (Of course, in any sensible call of the function, it
400        won't be NULL.)
402     3. The memmove() emulation function in pcre_internal.h, which is used on
403        systems that lack both memmove() and bcopy() - that is, hardly ever -
404        was missing a "static" storage class specifier.
406     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
407        containing an extended class (one that cannot be represented by a bitmap
408        because it contains high-valued characters or Unicode property items, e.g.
409        [\pZ]). Almost always one would set UTF-8 mode when processing such a
410        pattern, but PCRE should not loop if you do not (it no longer does).
411        [Detail: two cases were found: (a) a repeated subpattern containing an
412        extended class; (b) a recursive reference to a subpattern that followed a
413        previous extended class. It wasn't skipping over the extended class
414        correctly when UTF-8 mode was not set.]
416     5. A negated single-character class was not being recognized as fixed-length
417        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
418        compile error "lookbehind assertion is not fixed length".
420     6. The RunPerlTest auxiliary script was showing an unexpected difference
421        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
422        write a Perl script that can interpret lines of an input file either as
423        byte characters or as UTF-8, which is what "perltest" was being required to
424        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
425        can't do is switch easily at run time between having the "use utf8;" pragma
426        or not. In the end, I fudged it by using the RunPerlTest script to insert
427        "use utf8;" explicitly for the UTF-8 tests.
429     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
430        the end of the subject string, contrary to the documentation and to what
431        Perl does. This was true of both matching functions. Now it matches only at
432        the start of the subject and immediately after *internal* newlines.
434     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
435        a pointer to an int instead of a pointer to an unsigned long int. This
436        caused problems on 64-bit systems.
438     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
439        instance of the 'standard' template library not being so standard".
441    10. There was no check on the number of named subpatterns nor the maximum
442        length of a subpattern name. The product of these values is used to compute
443        the size of the memory block for a compiled pattern. By supplying a very
444        long subpattern name and a large number of named subpatterns, the size
445        computation could be caused to overflow. This is now prevented by limiting
446        the length of names to 32 characters, and the number of named subpatterns
447        to 10,000.
449    11. Subpatterns that are repeated with specific counts have to be replicated in
450        the compiled pattern. The size of memory for this was computed from the
451        length of the subpattern and the repeat count. The latter is limited to
452        65535, but there was no limit on the former, meaning that integer overflow
453        could in principle occur. The compiled length of a repeated subpattern is
454        now limited to 30,000 bytes in order to prevent this.
456    12. Added the optional facility to have named substrings with the same name.
458    13. Added the ability to use a named substring as a condition, using the
459        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
460        are numbers (not recommended). Forward references are permitted.
462    14. Added forward references in named backreferences (if you see what I mean).
464    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
465        pattern could run off the end of the subject. For example, the pattern
466        "(?s)(.{1,5})"8 did this with the subject "ab".
468    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
469        PCRE_CASELESS was set when matching characters that were quantified with ?
470        or *.
472    17. A character class other than a single negated character that had a minimum
473        but no maximum quantifier - for example [ab]{6,} - was not handled
474        correctly by pce_dfa_exec(). It would match only one character.
476    18. A valid (though odd) pattern that looked like a POSIX character
477        class but used an invalid character after [ (for example [[,abc,]]) caused
478        pcre_compile() to give the error "Failed: internal error: code overflow" or
479        in some cases to crash with a glibc free() error. This could even happen if
480        the pattern terminated after [[ but there just happened to be a sequence of
481        letters, a binary zero, and a closing ] in the memory that followed.
483    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
484        over the years. Originally (before any Unicode support), just the bottom 8
485        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
486        output from "man perlunicode" includes this:
488          The regular expression compiler produces polymorphic opcodes.  That
489          is, the pattern adapts to the data and automatically switches to
490          the Unicode character scheme when presented with Unicode data--or
491          instead uses a traditional byte scheme when presented with byte
492          data.
494        Sadly, a wide octal escape does not cause a switch, and in a string with
495        no other multibyte characters, these octal escapes are treated as before.
496        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
497        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
498        Unicode string.
500        I have not perpetrated such confusion in PCRE. Up till now, it took just
501        the bottom 8 bits, as in old Perl. I have now made octal escapes with
502        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
503        translate to the appropriate multibyte character.
505    29. Applied some refactoring to reduce the number of warnings from Microsoft
506        and Borland compilers. This has included removing the fudge introduced
507        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
508        a warning about an unused variable.
510    21. PCRE has not included VT (character 0x0b) in the set of whitespace
511        characters since release 4.0, because Perl (from release 5.004) does not.
512        [Or at least, is documented not to: some releases seem to be in conflict
513        with the documentation.] However, when a pattern was studied with
514        pcre_study() and all its branches started with \s, PCRE still included VT
515        as a possible starting character. Of course, this did no harm; it just
516        caused an unnecessary match attempt.
518    22. Removed a now-redundant internal flag bit that recorded the fact that case
519        dependency changed within the pattern. This was once needed for "required
520        byte" processing, but is no longer used. This recovers a now-scarce options
521        bit. Also moved the least significant internal flag bit to the most-
522        significant bit of the word, which was not previously used (hangover from
523        the days when it was an int rather than a uint) to free up another bit for
524        the future.
526    23. Added support for CRLF line endings as well as CR and LF. As well as the
527        default being selectable at build time, it can now be changed at runtime
528        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
529        specify that it is scanning data with non-default line endings.
531    24. Changed the definition of CXXLINK to make it agree with the definition of
532        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
534    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
535        recursions. This makes a big different to stack usage for some patterns.
537    26. If a subpattern containing a named recursion or subroutine reference such
538        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
539        the space required for the compiled pattern went wrong and gave too small a
540        value. Depending on the environment, this could lead to "Failed: internal
541        error: code overflow at offset 49" or "glibc detected double free or
542        corruption" errors.
544    27. Applied patches from Google (a) to support the new newline modes and (b) to
545        advance over multibyte UTF-8 characters in GlobalReplace.
547    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
548        difference for some implementation of PCRE in some Windows version.
550    29. Added some extra testing facilities to pcretest:
552        \q<number>   in a data line sets the "match limit" value
553        \Q<number>   in a data line sets the "match recursion limt" value
554        -S <number>  sets the stack size, where <number> is in megabytes
556        The -S option isn't available for Windows.
559    Version 6.6 06-Feb-06
560    ---------------------
562     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
563        in pcreposix.h. I have copied the definition from pcre.h.
565     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
566        because pcre.h is no longer a built file.
568     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
569        not normally included in the compiled code.
572    Version 6.5 01-Feb-06
573    ---------------------
575     1. When using the partial match feature with pcre_dfa_exec(), it was not
576        anchoring the second and subsequent partial matches at the new starting
577        point. This could lead to incorrect results. For example, with the pattern
578        /1234/, partially matching against "123" and then "a4" gave a match.
580     2. Changes to pcregrep:
582        (a) All non-match returns from pcre_exec() were being treated as failures
583            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
584            error message is output. Some extra information is given for the
585            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
586            probably the only errors that are likely to be caused by users (by
587            specifying a regex that has nested indefinite repeats, for instance).
588            If there are more than 20 of these errors, pcregrep is abandoned.
590        (b) A binary zero was treated as data while matching, but terminated the
591            output line if it was written out. This has been fixed: binary zeroes
592            are now no different to any other data bytes.
594        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
595            used to set a locale for matching. The --locale=xxxx long option has
596            been added (no short equivalent) to specify a locale explicitly on the
597            pcregrep command, overriding the environment variables.
599        (d) When -B was used with -n, some line numbers in the output were one less
600            than they should have been.
602        (e) Added the -o (--only-matching) option.
604        (f) If -A or -C was used with -c (count only), some lines of context were
605            accidentally printed for the final match.
607        (g) Added the -H (--with-filename) option.
609        (h) The combination of options -rh failed to suppress file names for files
610            that were found from directory arguments.
612        (i) Added the -D (--devices) and -d (--directories) options.
614        (j) Added the -F (--fixed-strings) option.
616        (k) Allow "-" to be used as a file name for -f as well as for a data file.
618        (l) Added the --colo(u)r option.
620        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
621            is not present by default.
623     3. A nasty bug was discovered in the handling of recursive patterns, that is,
624        items such as (?R) or (?1), when the recursion could match a number of
625        alternatives. If it matched one of the alternatives, but subsequently,
626        outside the recursion, there was a failure, the code tried to back up into
627        the recursion. However, because of the way PCRE is implemented, this is not
628        possible, and the result was an incorrect result from the match.
630        In order to prevent this happening, the specification of recursion has
631        been changed so that all such subpatterns are automatically treated as
632        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
634     4. I had overlooked the fact that, in some locales, there are characters for
635        which isalpha() is true but neither isupper() nor islower() are true. In
636        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
637        and ordfeminine) are like this. This affected the treatment of \w and \W
638        when they appeared in character classes, but not when they appeared outside
639        a character class. The bit map for "word" characters is now created
640        separately from the results of isalnum() instead of just taking it from the
641        upper, lower, and digit maps. (Plus the underscore character, of course.)
643     5. The above bug also affected the handling of POSIX character classes such as
644        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
645        permanent tables. Instead, the bit maps for such a class were previously
646        created as the appropriate unions of the upper, lower, and digit bitmaps.
647        Now they are created by subtraction from the [[:word:]] class, which has
648        its own bitmap.
650     6. The [[:blank:]] character class matches horizontal, but not vertical space.
651        It is created by subtracting the vertical space characters (\x09, \x0a,
652        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
653        subtraction was done in the overall bitmap for a character class, meaning
654        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
655        be recognized. This bug has been fixed.
657     7. Patches from the folks at Google:
659          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
660          real life, but is still worth protecting against".
662          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
663          regular expressions".
665          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
666          have it.
668          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
669          "configure" and the latter not, in order to fix a problem somebody had
670          with compiling the Arg class on HP-UX.
672          (e) Improve the error-handling of the C++ wrapper a little bit.
674          (f) New tests for checking recursion limiting.
676     8. The pcre_memmove() function, which is used only if the environment does not
677        have a standard memmove() function (and is therefore rarely compiled),
678        contained two bugs: (a) use of int instead of size_t, and (b) it was not
679        returning a result (though PCRE never actually uses the result).
681     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
682        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
683        returned instead of calling malloc() with an overflowing number that would
684        most likely cause subsequent chaos.
686    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
688    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
689        with this option is matched, the nmatch and pmatch options of regexec() are
690        ignored.
692    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
693        provided in case anyone wants to the the POSIX interface with UTF-8
694        strings.
696    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
697        C++ linking (needed for some HP-UX environments).
699    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
700        (unused parameter) and in the pcre_printint() function (omitted "default"
701        switch label when the default is to do nothing).
703    15. Added some code to make it possible, when PCRE is compiled as a C++
704        library, to replace subject pointers for pcre_exec() with a smart pointer
705        class, thus making it possible to process discontinuous strings.
707    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
708        much the same function. They were added by different people who were trying
709        to make PCRE easy to compile on non-Unix systems. It has been suggested
710        that PCRE_EXPORT be abolished now that there is more automatic apparatus
711        for compiling on Windows systems. I have therefore replaced it with
712        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
713        defaults to "extern" for C or "extern C" for C++, which works fine on
714        Unix-like systems. It is now possible to override the value of PCRE_DATA_
715        SCOPE with something explicit in config.h. In addition:
717        (a) pcreposix.h still had just "extern" instead of either of these macros;
718            I have replaced it with PCRE_DATA_SCOPE.
720        (b) Functions such as _pcre_xclass(), which are internal to the library,
721            but external in the C sense, all had PCRE_EXPORT in their definitions.
722            This is apparently wrong for the Windows case, so I have removed it.
723            (It makes no difference on Unix-like systems.)
725    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
726        of recursive calls to match(). This is different to MATCH_LIMIT because
727        that limits the total number of calls to match(), not all of which increase
728        the depth of recursion. Limiting the recursion depth limits the amount of
729        stack (or heap if NO_RECURSE is set) that is used. The default can be set
730        when PCRE is compiled, and changed at run time. A patch from Google adds
731        this functionality to the C++ interface.
733    18. Changes to the handling of Unicode character properties:
735        (a) Updated the table to Unicode 4.1.0.
737        (b) Recognize characters that are not in the table as "Cn" (undefined).
739        (c) I revised the way the table is implemented to a much improved format
740            which includes recognition of ranges. It now supports the ranges that
741            are defined in UnicodeData.txt, and it also amalgamates other
742            characters into ranges. This has reduced the number of entries in the
743            table from around 16,000 to around 3,000, thus reducing its size
744            considerably. I realized I did not need to use a tree structure after
745            all - a binary chop search is just as efficient. Having reduced the
746            number of entries, I extended their size from 6 bytes to 8 bytes to
747            allow for more data.
749        (d) Added support for Unicode script names via properties such as \p{Han}.
751    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
752        matching that character.
754    20. When matching a repeated Unicode property with a minimum greater than zero,
755        (for example \pL{2,}), PCRE could look past the end of the subject if it
756        reached it while seeking the minimum number of characters. This could
757        happen only if some of the characters were more than one byte long, because
758        there is a check for at least the minimum number of bytes.
760    21. Refactored the implementation of \p and \P so as to be more general, to
761        allow for more different types of property in future. This has changed the
762        compiled form incompatibly. Anybody with saved compiled patterns that use
763        \p or \P will have to recompile them.
765    22. Added "Any" and "L&" to the supported property types.
767    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
768        but give a compile time error if the value is greater than 0xff.
770    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
771        accidentally not being installed or uninstalled.
773    25. The pcre.h file was built from pcre.h.in, but the only changes that were
774        made were to insert the current release number. This seemed silly, because
775        it made things harder for people building PCRE on systems that don't run
776        "configure". I have turned pcre.h into a distributed file, no longer built
777        by "configure", with the version identification directly included. There is
778        no longer a pcre.h.in file.
780        However, this change necessitated a change to the pcre-config script as
781        well. It is built from pcre-config.in, and one of the substitutions was the
782        release number. I have updated configure.ac so that ./configure now finds
783        the release number by grepping pcre.h.
785    26. Added the ability to run the tests under valgrind.
788    Version 6.4 05-Sep-05
789    ---------------------
791     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
792        "--" to be printed when multiple files were scanned, even when none of the
793        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
794        consider it to be a bug, and have restored the previous behaviour.
796     2. A couple of code tidies to get rid of compiler warnings.
798     3. The pcretest program used to cheat by referring to symbols in the library
799        whose names begin with _pcre_. These are internal symbols that are not
800        really supposed to be visible externally, and in some environments it is
801        possible to suppress them. The cheating is now confined to including
802        certain files from the library's source, which is a bit cleaner.
804     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
805        file's purpose clearer.
807     5. Reorganized pcre_ucp_findchar().
810  Version 6.3 15-Aug-05  Version 6.3 15-Aug-05
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