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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.3 05-Jul-07
5    ---------------------
7     1. In the rejigging of the build system that eventually resulted in 7.1, the
8        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
9        brackets there is not right, since it causes compilers to look for an
10        installed pcre.h, not the version that is in the source that is being
11        compiled (which of course may be different). I have changed it back to:
13          #include "pcre.h"
15        I have a vague recollection that the change was concerned with compiling in
16        different directories, but in the new build system, that is taken care of
17        by the VPATH setting the Makefile.
19     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
20        when the subject happened to end in the byte 0x85 (e.g. if the last
21        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
22        characters but of course it shouldn't be taken as a newline when it is part
23        of another character. The bug was that, for an unlimited repeat of . in
24        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
25        characters when looking for a newline.
27     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
29     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
30        in debug output.
32     5. Arrange to use "%I64d" instead of "%lld" for long printing in the pcrecpp
33        unittest when running under MinGW.
35     6. ESC_K was left out of the EBCDIC table.
37     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
38        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
39        limit also applies to "virtual nesting" when a pattern is recursive, and in
40        this case 1000 isn't so big. I have been able to remove this limit at the
41        expense of backing off one optimization in certain circumstances. Normally,
42        when pcre_exec() would call its internal match() function recursively and
43        immediately return the result unconditionally, it uses a "tail recursion"
44        feature to save stack. However, when a subpattern that can match an empty
45        string has an unlimited repetition quantifier, it no longer makes this
46        optimization. That gives it a stack frame in which to save the data for
47        checking that an empty string has been matched. Previously this was taken
48        from the 1000-entry workspace that had been reserved. So now there is no
49        explicit limit, but more stack is used.
51     8. Applied Daniel's patches to solve problems with the import/export magic
52        syntax that is required for Windows, and which was going wrong for the
53        pcreposix and pcrecpp parts of the library. These were overlooked when this
54        problem was solved for the main library.
57    Version 7.2 19-Jun-07
58    ---------------------
60     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
61        which is apparently normally available under Windows.
63     2. Re-jig the pcregrep tests with different newline settings in an attempt
64        to make them independent of the local environment's newline setting.
66     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
68     4. Some of the "internals" tests were previously cut out when the link size
69        was not 2, because the output contained actual offsets. The recent new
70        "Z" feature of pcretest means that these can be cut out, making the tests
71        usable with all link sizes.
73     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
74        stack recursion. This gives a massive performance boost under BSD, but just
75        a small improvement under Linux. However, it saves one field in the frame
76        in all cases.
78     6. Added more features from the forthcoming Perl 5.10:
80        (a) (?-n) (where n is a string of digits) is a relative subroutine or
81            recursion call. It refers to the nth most recently opened parentheses.
83        (b) (?+n) is also a relative subroutine call; it refers to the nth next
84            to be opened parentheses.
86        (c) Conditions that refer to capturing parentheses can be specified
87            relatively, for example, (?(-2)... or (?(+3)...
89        (d) \K resets the start of the current match so that everything before
90            is not part of it.
92        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
94        (f) \g{name} is another synonym - part of Perl 5.10's unification of
95            reference syntax.
97        (g) (?| introduces a group in which the numbering of parentheses in each
98            alternative starts with the same number.
100        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
102     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
105     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
106        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
107        for detecting groups that can match an empty string.
109     9. A pattern with a very large number of alternatives (more than several
110        hundred) was running out of internal workspace during the pre-compile
111        phase, where pcre_compile() figures out how much memory will be needed. A
112        bit of new cunning has reduced the workspace needed for groups with
113        alternatives. The 1000-alternative test pattern now uses 12 bytes of
114        workspace instead of running out of the 4096 that are available.
116    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
118    11. Applied patch from Google to remove an optimization that didn't quite work.
119        The report of the bug said:
121          pcrecpp::RE("a*").FullMatch("aaa") matches, while
122          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
123          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
125    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
126        it matched the wrong number of bytes.
129    Version 7.1 24-Apr-07
130    ---------------------
132     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
133        that is more "standard", making use of automake and other Autotools. There
134        is some re-arrangement of the files and adjustment of comments consequent
135        on this.
137     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
138        for recursive directory scanning broke on some systems because the files
139        are not scanned in any specific order and on different systems the order
140        was different. A call to "sort" has been inserted into RunGrepTest for the
141        approprate test as a short-term fix. In the longer term there may be an
142        alternative.
144     3. I had an email from Eric Raymond about problems translating some of PCRE's
145        man pages to HTML (despite the fact that I distribute HTML pages, some
146        people do their own conversions for various reasons). The problems
147        concerned the use of low-level troff macros .br and .in. I have therefore
148        removed all such uses from the man pages (some were redundant, some could
149        be replaced by .nf/.fi pairs). The 132html script that I use to generate
150        HTML has been updated to handle .nf/.fi and to complain if it encounters
151        .br or .in.
153     4. Updated comments in configure.ac that get placed in config.h.in and also
154        arranged for config.h to be included in the distribution, with the name
155        config.h.generic, for the benefit of those who have to compile without
156        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
158     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
159        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
160        makevp.bat for the current PCRE, using the additional files
161        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
163     6. A Windows user reported a minor discrepancy with test 2, which turned out
164        to be caused by a trailing space on an input line that had got lost in his
165        copy. The trailing space was an accident, so I've just removed it.
167     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
168        that is needed.
170     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
171        as "const" (a) because they are and (b) because it helps the PHP
172        maintainers who have recently made a script to detect big data structures
173        in the php code that should be moved to the .rodata section. I remembered
174        to update Builducptable as well, so it won't revert if ucptable.h is ever
175        re-created.
177     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
178        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
179        order to be able to cut out the UTF-8 tables in the latter when UTF-8
180        support is not required. This saves 1.5-2K of code, which is important in
181        some applications.
183        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
184        so as not to refer to the tables, even though these functions will never be
185        called when UTF-8 support is disabled. Otherwise there are problems with a
186        shared library.
188    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
190        (a) It was defining its arguments as char * instead of void *.
192        (b) It was assuming that all moves were upwards in memory; this was true
193            a long time ago when I wrote it, but is no longer the case.
195        The emulated memove() is provided for those environments that have neither
196        memmove() nor bcopy(). I didn't think anyone used it these days, but that
197        is clearly not the case, as these two bugs were recently reported.
199    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
200        and Detrail to create the HTML documentation, the .txt form of the man
201        pages, and it removes trailing spaces from listed files. It also creates
202        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
203        case, it wraps all the #defines with #ifndefs. This script should be run
204        before "make dist".
206    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
207        with Unicode property support.
209        (a) For a maximizing quantifier, if the two different cases of the
210            character were of different lengths in their UTF-8 codings (there are
211            some cases like this - I found 11), and the matching function had to
212            back up over a mixture of the two cases, it incorrectly assumed they
213            were both the same length.
215        (b) When PCRE was configured to use the heap rather than the stack for
216            recursion during matching, it was not correctly preserving the data for
217            the other case of a UTF-8 character when checking ahead for a match
218            while processing a minimizing repeat. If the check also involved
219            matching a wide character, but failed, corruption could cause an
220            erroneous result when trying to check for a repeat of the original
221            character.
223    13. Some tidying changes to the testing mechanism:
225        (a) The RunTest script now detects the internal link size and whether there
226            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
227            values substituted by "configure". (The RunGrepTest script already did
228            this for UTF-8.) The configure.ac script no longer substitutes the
229            relevant variables.
231        (b) The debugging options /B and /D in pcretest show the compiled bytecode
232            with length and offset values. This means that the output is different
233            for different internal link sizes. Test 2 is skipped for link sizes
234            other than 2 because of this, bypassing the problem. Unfortunately,
235            there was also a test in test 3 (the locale tests) that used /B and
236            failed for link sizes other than 2. Rather than cut the whole test out,
237            I have added a new /Z option to pcretest that replaces the length and
238            offset values with spaces. This is now used to make test 3 independent
239            of link size. (Test 2 will be tidied up later.)
241    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
242        segmentation fault instead of returning the appropriate error message.
244    15. In multiline mode when the newline sequence was set to "any", the pattern
245        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
246        This doesn't seem right; it now treats the CRLF combination as the line
247        ending, and so does not match in that case. It's only a pattern such as ^$
248        that would hit this one: something like ^ABC$ would have failed after \r
249        and then tried again after \r\n.
251    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
252        in an attempt to make files that differ only in their line terminators
253        compare equal. This works on Linux.
255    17. Under certain error circumstances pcregrep might try to free random memory
256        as it exited. This is now fixed, thanks to valgrind.
258    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
259        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
260        was because its rules for how to advance for /g after matching an empty
261        string at the end of a line did not allow for this case. They now check for
262        it specially.
264    20. pcretest is supposed to handle patterns and data of any length, by
265        extending its buffers when necessary. It was getting this wrong when the
266        buffer for a data line had to be extended.
268    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
269        CRLF as a newline sequence.
271    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
272        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
273        I have nevertheless tidied it up.
275    23. Added some casts to kill warnings from HP-UX ia64 compiler.
277    24. Added a man page for pcre-config.
280    Version 7.0 19-Dec-06
281    ---------------------
283     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
284        moving to gcc 4.1.1.
286     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
287        sys/time.h, which is documented as needed for this function. It doesn't
288        seem to matter on Linux, but it showed up on some releases of OS X.
290     3. It seems that there are systems where bytes whose values are greater than
291        127 match isprint() in the "C" locale. The "C" locale should be the
292        default when a C program starts up. In most systems, only ASCII printing
293        characters match isprint(). This difference caused the output from pcretest
294        to vary, making some of the tests fail. I have changed pcretest so that:
296        (a) When it is outputting text in the compiled version of a pattern, bytes
297            other than 32-126 are always shown as hex escapes.
299        (b) When it is outputting text that is a matched part of a subject string,
300            it does the same, unless a different locale has been set for the match
301            (using the /L modifier). In this case, it uses isprint() to decide.
303     4. Fixed a major bug that caused incorrect computation of the amount of memory
304        required for a compiled pattern when options that changed within the
305        pattern affected the logic of the preliminary scan that determines the
306        length. The relevant options are -x, and -i in UTF-8 mode. The result was
307        that the computed length was too small. The symptoms of this bug were
308        either the PCRE error "internal error: code overflow" from pcre_compile(),
309        or a glibc crash with a message such as "pcretest: free(): invalid next
310        size (fast)". Examples of patterns that provoked this bug (shown in
311        pcretest format) are:
313          /(?-x: )/x
314          /(?x)(?-x: \s*#\s*)/
315          /((?i)[\x{c0}])/8
316          /(?i:[\x{c0}])/8
318        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
319        is now done differently.
321     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
322        wrapper classes; (b) implement a new function in the C++ scanner that is
323        more efficient than the old way of doing things because it avoids levels of
324        recursion in the regex matching; (c) add a paragraph to the documentation
325        for the FullMatch() function.
327     6. The escape sequence \n was being treated as whatever was defined as
328        "newline". Not only was this contrary to the documentation, which states
329        that \n is character 10 (hex 0A), but it also went horribly wrong when
330        "newline" was defined as CRLF. This has been fixed.
332     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
333        was being set to -1 for the "end of line" case (supposedly a value that no
334        character can have). Though this value is never used (the check for end of
335        line is "zero bytes in current character"), it caused compiler complaints.
336        I've changed it to 0xffffffff.
338     8. In pcre_version.c, the version string was being built by a sequence of
339        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
340        string (as it is for production releases) called a macro with an empty
341        argument. The C standard says the result of this is undefined. The gcc
342        compiler treats it as an empty string (which was what was wanted) but it is
343        reported that Visual C gives an error. The source has been hacked around to
344        avoid this problem.
346     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
347        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
348        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
349        of them did).
351    10. Originally, pcretest opened its input and output without "b"; then I was
352        told that "b" was needed in some environments, so it was added for release
353        5.0 to both the input and output. (It makes no difference on Unix-like
354        systems.) Later I was told that it is wrong for the input on Windows. I've
355        now abstracted the modes into two macros, to make it easier to fiddle with
356        them, and removed "b" from the input mode under Windows.
358    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
360    12. Added -help and --help to pcretest as an official way of being reminded
361        of the options.
363    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
364        and pcrecpp.cc because they annoy compilers at high warning levels.
366    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
368    15. Fixed an occurrence of == in configure.ac that should have been = (shell
369        scripts are not C programs :-) and which was not noticed because it works
370        on Linux.
372    16. pcretest is supposed to handle any length of pattern and data line (as one
373        line or as a continued sequence of lines) by extending its input buffer if
374        necessary. This feature was broken for very long pattern lines, leading to
375        a string of junk being passed to pcre_compile() if the pattern was longer
376        than about 50K.
378    17. I have done a major re-factoring of the way pcre_compile() computes the
379        amount of memory needed for a compiled pattern. Previously, there was code
380        that made a preliminary scan of the pattern in order to do this. That was
381        OK when PCRE was new, but as the facilities have expanded, it has become
382        harder and harder to keep it in step with the real compile phase, and there
383        have been a number of bugs (see for example, 4 above). I have now found a
384        cunning way of running the real compile function in a "fake" mode that
385        enables it to compute how much memory it would need, while actually only
386        ever using a few hundred bytes of working memory and without too many
387        tests of the mode. This should make future maintenance and development
388        easier. A side effect of this work is that the limit of 200 on the nesting
389        depth of parentheses has been removed (though this was never a serious
390        limitation, I suspect). However, there is a downside: pcre_compile() now
391        runs more slowly than before (30% or more, depending on the pattern). I
392        hope this isn't a big issue. There is no effect on runtime performance.
394    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
395        newline (only possible for the last line of a file) and it was a
396        pattern that set a locale (followed by /Lsomething), pcretest crashed.
398    19. Added additional timing features to pcretest. (1) The -tm option now times
399        matching only, not compiling. (2) Both -t and -tm can be followed, as a
400        separate command line item, by a number that specifies the number of
401        repeats to use when timing. The default is 50000; this gives better
402        precision, but takes uncomfortably long for very large patterns.
404    20. Extended pcre_study() to be more clever in cases where a branch of a
405        subpattern has no definite first character. For example, (a*|b*)[cd] would
406        previously give no result from pcre_study(). Now it recognizes that the
407        first character must be a, b, c, or d.
409    21. There was an incorrect error "recursive call could loop indefinitely" if
410        a subpattern (or the entire pattern) that was being tested for matching an
411        empty string contained only one non-empty item after a nested subpattern.
412        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
413        incorrectly, because the \d was being skipped in the check.
415    22. The pcretest program now has a new pattern option /B and a command line
416        option -b, which is equivalent to adding /B to every pattern. This causes
417        it to show the compiled bytecode, without the additional information that
418        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
419        is the same as /B/I).
421    23. A new optimization is now able automatically to treat some sequences such
422        as a*b as a*+b. More specifically, if something simple (such as a character
423        or a simple class like \d) has an unlimited quantifier, and is followed by
424        something that cannot possibly match the quantified thing, the quantifier
425        is automatically "possessified".
427    24. A recursive reference to a subpattern whose number was greater than 39
428        went wrong under certain circumstances in UTF-8 mode. This bug could also
429        have affected the operation of pcre_study().
431    25. Realized that a little bit of performance could be had by replacing
432        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
434    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
436    27. Possessive quantifiers such as a++ were previously implemented by turning
437        them into atomic groups such as ($>a+). Now they have their own opcodes,
438        which improves performance. This includes the automatically created ones
439        from 23 above.
441    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
442        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
443        the first matched character to be a colon. This applied both to named and
444        numbered groups.
446    29. The ucpinternal.h header file was missing its idempotency #ifdef.
448    30. I was sent a "project" file called libpcre.a.dev which I understand makes
449        building PCRE on Windows easier, so I have included it in the distribution.
451    31. There is now a check in pcretest against a ridiculously large number being
452        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
453        loop, the loop is abandoned.
455    32. Forward references to subpatterns in conditions such as (?(2)...) where
456        subpattern 2 is defined later cause pcre_compile() to search forwards in
457        the pattern for the relevant set of parentheses. This search went wrong
458        when there were unescaped parentheses in a character class, parentheses
459        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
461    33. "Subroutine" calls and backreferences were previously restricted to
462        referencing subpatterns earlier in the regex. This restriction has now
463        been removed.
465    34. Added a number of extra features that are going to be in Perl 5.10. On the
466        whole, these are just syntactic alternatives for features that PCRE had
467        previously implemented using the Python syntax or my own invention. The
468        other formats are all retained for compatibility.
470        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
471            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
472            also .NET compatible.
474        (b) A recursion or subroutine call to a named group can now be defined as
475            (?&name) as well as (?P>name).
477        (c) A backreference to a named group can now be defined as \k<name> or
478            \k'name' as well as (?P=name). The new forms, as well as being in Perl
479            5.10, are also .NET compatible.
481        (d) A conditional reference to a named group can now use the syntax
482            (?(<name>) or (?('name') as well as (?(name).
484        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
485            groups (named and numbered) that are never evaluated inline, but can be
486            called as "subroutines" from elsewhere. In effect, the DEFINE condition
487            is always false. There may be only one alternative in such a group.
489        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
490            as the simple (?(R). The condition is true only if the most recent
491            recursion is that of the given number or name. It does not search out
492            through the entire recursion stack.
494        (g) The escape \gN or \g{N} has been added, where N is a positive or
495            negative number, specifying an absolute or relative reference.
497    35. Tidied to get rid of some further signed/unsigned compiler warnings and
498        some "unreachable code" warnings.
500    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
501        things, this adds five new scripts.
503    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
504        There were also incompatibilities regarding the handling of \Q..\E inside
505        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
506        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
508    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
509        matches an empty string, and forcibly breaks the loop. There were bugs in
510        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
511        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
512        separate and independent bugs (that affected different cases) have been
513        fixed.
515    39. Refactored the code to abolish the use of different opcodes for small
516        capturing bracket numbers. This is a tidy that I avoided doing when I
517        removed the limit on the number of capturing brackets for 3.5 back in 2001.
518        The new approach is not only tidier, it makes it possible to reduce the
519        memory needed to fix the previous bug (38).
521    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
522        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
523        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
524        mode.
526    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
527        report.
529    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
530        copy construction and assignment in the C++ wrapper.
532    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
533        couple of bugs that could have given wrong results in the "--newline=crlf"
534        case.
536    44. Added a number of casts and did some reorganization of signed/unsigned int
537        variables following suggestions from Dair Grant. Also renamed the variable
538        "this" as "item" because it is a C++ keyword.
540    45. Arranged for dftables to add
542          #include "pcre_internal.h"
544        to pcre_chartables.c because without it, gcc 4.x may remove the array
545        definition from the final binary if PCRE is built into a static library and
546        dead code stripping is activated.
548    46. For an unanchored pattern, if a match attempt fails at the start of a
549        newline sequence, and the newline setting is CRLF or ANY, and the next two
550        characters are CRLF, advance by two characters instead of one.
553    Version 6.7 04-Jul-06
554    ---------------------
556     1. In order to handle tests when input lines are enormously long, pcretest has
557        been re-factored so that it automatically extends its buffers when
558        necessary. The code is crude, but this _is_ just a test program. The
559        default size has been increased from 32K to 50K.
561     2. The code in pcre_study() was using the value of the re argument before
562        testing it for NULL. (Of course, in any sensible call of the function, it
563        won't be NULL.)
565     3. The memmove() emulation function in pcre_internal.h, which is used on
566        systems that lack both memmove() and bcopy() - that is, hardly ever -
567        was missing a "static" storage class specifier.
569     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
570        containing an extended class (one that cannot be represented by a bitmap
571        because it contains high-valued characters or Unicode property items, e.g.
572        [\pZ]). Almost always one would set UTF-8 mode when processing such a
573        pattern, but PCRE should not loop if you do not (it no longer does).
574        [Detail: two cases were found: (a) a repeated subpattern containing an
575        extended class; (b) a recursive reference to a subpattern that followed a
576        previous extended class. It wasn't skipping over the extended class
577        correctly when UTF-8 mode was not set.]
579     5. A negated single-character class was not being recognized as fixed-length
580        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
581        compile error "lookbehind assertion is not fixed length".
583     6. The RunPerlTest auxiliary script was showing an unexpected difference
584        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
585        write a Perl script that can interpret lines of an input file either as
586        byte characters or as UTF-8, which is what "perltest" was being required to
587        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
588        can't do is switch easily at run time between having the "use utf8;" pragma
589        or not. In the end, I fudged it by using the RunPerlTest script to insert
590        "use utf8;" explicitly for the UTF-8 tests.
592     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
593        the end of the subject string, contrary to the documentation and to what
594        Perl does. This was true of both matching functions. Now it matches only at
595        the start of the subject and immediately after *internal* newlines.
597     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
598        a pointer to an int instead of a pointer to an unsigned long int. This
599        caused problems on 64-bit systems.
601     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
602        instance of the 'standard' template library not being so standard".
604    10. There was no check on the number of named subpatterns nor the maximum
605        length of a subpattern name. The product of these values is used to compute
606        the size of the memory block for a compiled pattern. By supplying a very
607        long subpattern name and a large number of named subpatterns, the size
608        computation could be caused to overflow. This is now prevented by limiting
609        the length of names to 32 characters, and the number of named subpatterns
610        to 10,000.
612    11. Subpatterns that are repeated with specific counts have to be replicated in
613        the compiled pattern. The size of memory for this was computed from the
614        length of the subpattern and the repeat count. The latter is limited to
615        65535, but there was no limit on the former, meaning that integer overflow
616        could in principle occur. The compiled length of a repeated subpattern is
617        now limited to 30,000 bytes in order to prevent this.
619    12. Added the optional facility to have named substrings with the same name.
621    13. Added the ability to use a named substring as a condition, using the
622        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
623        are numbers (not recommended). Forward references are permitted.
625    14. Added forward references in named backreferences (if you see what I mean).
627    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
628        pattern could run off the end of the subject. For example, the pattern
629        "(?s)(.{1,5})"8 did this with the subject "ab".
631    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
632        PCRE_CASELESS was set when matching characters that were quantified with ?
633        or *.
635    17. A character class other than a single negated character that had a minimum
636        but no maximum quantifier - for example [ab]{6,} - was not handled
637        correctly by pce_dfa_exec(). It would match only one character.
639    18. A valid (though odd) pattern that looked like a POSIX character
640        class but used an invalid character after [ (for example [[,abc,]]) caused
641        pcre_compile() to give the error "Failed: internal error: code overflow" or
642        in some cases to crash with a glibc free() error. This could even happen if
643        the pattern terminated after [[ but there just happened to be a sequence of
644        letters, a binary zero, and a closing ] in the memory that followed.
646    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
647        over the years. Originally (before any Unicode support), just the bottom 8
648        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
649        output from "man perlunicode" includes this:
651          The regular expression compiler produces polymorphic opcodes.  That
652          is, the pattern adapts to the data and automatically switches to
653          the Unicode character scheme when presented with Unicode data--or
654          instead uses a traditional byte scheme when presented with byte
655          data.
657        Sadly, a wide octal escape does not cause a switch, and in a string with
658        no other multibyte characters, these octal escapes are treated as before.
659        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
660        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
661        Unicode string.
663        I have not perpetrated such confusion in PCRE. Up till now, it took just
664        the bottom 8 bits, as in old Perl. I have now made octal escapes with
665        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
666        translate to the appropriate multibyte character.
668    29. Applied some refactoring to reduce the number of warnings from Microsoft
669        and Borland compilers. This has included removing the fudge introduced
670        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
671        a warning about an unused variable.
673    21. PCRE has not included VT (character 0x0b) in the set of whitespace
674        characters since release 4.0, because Perl (from release 5.004) does not.
675        [Or at least, is documented not to: some releases seem to be in conflict
676        with the documentation.] However, when a pattern was studied with
677        pcre_study() and all its branches started with \s, PCRE still included VT
678        as a possible starting character. Of course, this did no harm; it just
679        caused an unnecessary match attempt.
681    22. Removed a now-redundant internal flag bit that recorded the fact that case
682        dependency changed within the pattern. This was once needed for "required
683        byte" processing, but is no longer used. This recovers a now-scarce options
684        bit. Also moved the least significant internal flag bit to the most-
685        significant bit of the word, which was not previously used (hangover from
686        the days when it was an int rather than a uint) to free up another bit for
687        the future.
689    23. Added support for CRLF line endings as well as CR and LF. As well as the
690        default being selectable at build time, it can now be changed at runtime
691        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
692        specify that it is scanning data with non-default line endings.
694    24. Changed the definition of CXXLINK to make it agree with the definition of
695        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
697    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
698        recursions. This makes a big different to stack usage for some patterns.
700    26. If a subpattern containing a named recursion or subroutine reference such
701        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
702        the space required for the compiled pattern went wrong and gave too small a
703        value. Depending on the environment, this could lead to "Failed: internal
704        error: code overflow at offset 49" or "glibc detected double free or
705        corruption" errors.
707    27. Applied patches from Google (a) to support the new newline modes and (b) to
708        advance over multibyte UTF-8 characters in GlobalReplace.
710    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
711        difference for some implementation of PCRE in some Windows version.
713    29. Added some extra testing facilities to pcretest:
715        \q<number>   in a data line sets the "match limit" value
716        \Q<number>   in a data line sets the "match recursion limt" value
717        -S <number>  sets the stack size, where <number> is in megabytes
719        The -S option isn't available for Windows.
722  Version 6.6 06-Feb-06  Version 6.6 06-Feb-06
723  ---------------------  ---------------------

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