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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" and "%I64u" instead of "%llu" for
33        long printing in the pcrecpp 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.
56     9. There were some crude static tests to avoid integer overflow when computing
57        the size of patterns that contain repeated groups with explicit upper
58        limits. As the maximum quantifier is 65535, the maximum group length was
59        set at 30,000 so that the product of these two numbers did not overflow a
60        32-bit integer. However, it turns out that people want to use groups that
61        are longer than 30,000 bytes (though not repeat them that many times).
62        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
63        made it possible to implement the integer overflow checks in a much more
64        dynamic way, which I have now done. The artificial limitation on group
65        length has been removed - we now have only the limit on the total length of
66        the compiled pattern, which depends on the LINK_SIZE setting.
68    10. Fixed a bug in the documentation for get/copy named substring when
69        duplicate names are permitted. If none of the named substrings are set, the
70        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
71        empty string.
74    Version 7.2 19-Jun-07
75    ---------------------
77     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
78        which is apparently normally available under Windows.
80     2. Re-jig the pcregrep tests with different newline settings in an attempt
81        to make them independent of the local environment's newline setting.
83     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
85     4. Some of the "internals" tests were previously cut out when the link size
86        was not 2, because the output contained actual offsets. The recent new
87        "Z" feature of pcretest means that these can be cut out, making the tests
88        usable with all link sizes.
90     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
91        stack recursion. This gives a massive performance boost under BSD, but just
92        a small improvement under Linux. However, it saves one field in the frame
93        in all cases.
95     6. Added more features from the forthcoming Perl 5.10:
97        (a) (?-n) (where n is a string of digits) is a relative subroutine or
98            recursion call. It refers to the nth most recently opened parentheses.
100        (b) (?+n) is also a relative subroutine call; it refers to the nth next
101            to be opened parentheses.
103        (c) Conditions that refer to capturing parentheses can be specified
104            relatively, for example, (?(-2)... or (?(+3)...
106        (d) \K resets the start of the current match so that everything before
107            is not part of it.
109        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
111        (f) \g{name} is another synonym - part of Perl 5.10's unification of
112            reference syntax.
114        (g) (?| introduces a group in which the numbering of parentheses in each
115            alternative starts with the same number.
117        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
119     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
122     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
123        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
124        for detecting groups that can match an empty string.
126     9. A pattern with a very large number of alternatives (more than several
127        hundred) was running out of internal workspace during the pre-compile
128        phase, where pcre_compile() figures out how much memory will be needed. A
129        bit of new cunning has reduced the workspace needed for groups with
130        alternatives. The 1000-alternative test pattern now uses 12 bytes of
131        workspace instead of running out of the 4096 that are available.
133    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
135    11. Applied patch from Google to remove an optimization that didn't quite work.
136        The report of the bug said:
138          pcrecpp::RE("a*").FullMatch("aaa") matches, while
139          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
140          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
142    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
143        it matched the wrong number of bytes.
146    Version 7.1 24-Apr-07
147    ---------------------
149     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
150        that is more "standard", making use of automake and other Autotools. There
151        is some re-arrangement of the files and adjustment of comments consequent
152        on this.
154     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
155        for recursive directory scanning broke on some systems because the files
156        are not scanned in any specific order and on different systems the order
157        was different. A call to "sort" has been inserted into RunGrepTest for the
158        approprate test as a short-term fix. In the longer term there may be an
159        alternative.
161     3. I had an email from Eric Raymond about problems translating some of PCRE's
162        man pages to HTML (despite the fact that I distribute HTML pages, some
163        people do their own conversions for various reasons). The problems
164        concerned the use of low-level troff macros .br and .in. I have therefore
165        removed all such uses from the man pages (some were redundant, some could
166        be replaced by .nf/.fi pairs). The 132html script that I use to generate
167        HTML has been updated to handle .nf/.fi and to complain if it encounters
168        .br or .in.
170     4. Updated comments in configure.ac that get placed in config.h.in and also
171        arranged for config.h to be included in the distribution, with the name
172        config.h.generic, for the benefit of those who have to compile without
173        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
175     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
176        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
177        makevp.bat for the current PCRE, using the additional files
178        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
180     6. A Windows user reported a minor discrepancy with test 2, which turned out
181        to be caused by a trailing space on an input line that had got lost in his
182        copy. The trailing space was an accident, so I've just removed it.
184     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
185        that is needed.
187     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
188        as "const" (a) because they are and (b) because it helps the PHP
189        maintainers who have recently made a script to detect big data structures
190        in the php code that should be moved to the .rodata section. I remembered
191        to update Builducptable as well, so it won't revert if ucptable.h is ever
192        re-created.
194     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
195        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
196        order to be able to cut out the UTF-8 tables in the latter when UTF-8
197        support is not required. This saves 1.5-2K of code, which is important in
198        some applications.
200        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
201        so as not to refer to the tables, even though these functions will never be
202        called when UTF-8 support is disabled. Otherwise there are problems with a
203        shared library.
205    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
207        (a) It was defining its arguments as char * instead of void *.
209        (b) It was assuming that all moves were upwards in memory; this was true
210            a long time ago when I wrote it, but is no longer the case.
212        The emulated memove() is provided for those environments that have neither
213        memmove() nor bcopy(). I didn't think anyone used it these days, but that
214        is clearly not the case, as these two bugs were recently reported.
216    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
217        and Detrail to create the HTML documentation, the .txt form of the man
218        pages, and it removes trailing spaces from listed files. It also creates
219        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
220        case, it wraps all the #defines with #ifndefs. This script should be run
221        before "make dist".
223    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
224        with Unicode property support.
226        (a) For a maximizing quantifier, if the two different cases of the
227            character were of different lengths in their UTF-8 codings (there are
228            some cases like this - I found 11), and the matching function had to
229            back up over a mixture of the two cases, it incorrectly assumed they
230            were both the same length.
232        (b) When PCRE was configured to use the heap rather than the stack for
233            recursion during matching, it was not correctly preserving the data for
234            the other case of a UTF-8 character when checking ahead for a match
235            while processing a minimizing repeat. If the check also involved
236            matching a wide character, but failed, corruption could cause an
237            erroneous result when trying to check for a repeat of the original
238            character.
240    13. Some tidying changes to the testing mechanism:
242        (a) The RunTest script now detects the internal link size and whether there
243            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
244            values substituted by "configure". (The RunGrepTest script already did
245            this for UTF-8.) The configure.ac script no longer substitutes the
246            relevant variables.
248        (b) The debugging options /B and /D in pcretest show the compiled bytecode
249            with length and offset values. This means that the output is different
250            for different internal link sizes. Test 2 is skipped for link sizes
251            other than 2 because of this, bypassing the problem. Unfortunately,
252            there was also a test in test 3 (the locale tests) that used /B and
253            failed for link sizes other than 2. Rather than cut the whole test out,
254            I have added a new /Z option to pcretest that replaces the length and
255            offset values with spaces. This is now used to make test 3 independent
256            of link size. (Test 2 will be tidied up later.)
258    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
259        segmentation fault instead of returning the appropriate error message.
261    15. In multiline mode when the newline sequence was set to "any", the pattern
262        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
263        This doesn't seem right; it now treats the CRLF combination as the line
264        ending, and so does not match in that case. It's only a pattern such as ^$
265        that would hit this one: something like ^ABC$ would have failed after \r
266        and then tried again after \r\n.
268    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
269        in an attempt to make files that differ only in their line terminators
270        compare equal. This works on Linux.
272    17. Under certain error circumstances pcregrep might try to free random memory
273        as it exited. This is now fixed, thanks to valgrind.
275    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
276        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
277        was because its rules for how to advance for /g after matching an empty
278        string at the end of a line did not allow for this case. They now check for
279        it specially.
281    20. pcretest is supposed to handle patterns and data of any length, by
282        extending its buffers when necessary. It was getting this wrong when the
283        buffer for a data line had to be extended.
285    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
286        CRLF as a newline sequence.
288    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
289        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
290        I have nevertheless tidied it up.
292    23. Added some casts to kill warnings from HP-UX ia64 compiler.
294    24. Added a man page for pcre-config.
297    Version 7.0 19-Dec-06
298    ---------------------
300     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
301        moving to gcc 4.1.1.
303     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
304        sys/time.h, which is documented as needed for this function. It doesn't
305        seem to matter on Linux, but it showed up on some releases of OS X.
307     3. It seems that there are systems where bytes whose values are greater than
308        127 match isprint() in the "C" locale. The "C" locale should be the
309        default when a C program starts up. In most systems, only ASCII printing
310        characters match isprint(). This difference caused the output from pcretest
311        to vary, making some of the tests fail. I have changed pcretest so that:
313        (a) When it is outputting text in the compiled version of a pattern, bytes
314            other than 32-126 are always shown as hex escapes.
316        (b) When it is outputting text that is a matched part of a subject string,
317            it does the same, unless a different locale has been set for the match
318            (using the /L modifier). In this case, it uses isprint() to decide.
320     4. Fixed a major bug that caused incorrect computation of the amount of memory
321        required for a compiled pattern when options that changed within the
322        pattern affected the logic of the preliminary scan that determines the
323        length. The relevant options are -x, and -i in UTF-8 mode. The result was
324        that the computed length was too small. The symptoms of this bug were
325        either the PCRE error "internal error: code overflow" from pcre_compile(),
326        or a glibc crash with a message such as "pcretest: free(): invalid next
327        size (fast)". Examples of patterns that provoked this bug (shown in
328        pcretest format) are:
330          /(?-x: )/x
331          /(?x)(?-x: \s*#\s*)/
332          /((?i)[\x{c0}])/8
333          /(?i:[\x{c0}])/8
335        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
336        is now done differently.
338     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
339        wrapper classes; (b) implement a new function in the C++ scanner that is
340        more efficient than the old way of doing things because it avoids levels of
341        recursion in the regex matching; (c) add a paragraph to the documentation
342        for the FullMatch() function.
344     6. The escape sequence \n was being treated as whatever was defined as
345        "newline". Not only was this contrary to the documentation, which states
346        that \n is character 10 (hex 0A), but it also went horribly wrong when
347        "newline" was defined as CRLF. This has been fixed.
349     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
350        was being set to -1 for the "end of line" case (supposedly a value that no
351        character can have). Though this value is never used (the check for end of
352        line is "zero bytes in current character"), it caused compiler complaints.
353        I've changed it to 0xffffffff.
355     8. In pcre_version.c, the version string was being built by a sequence of
356        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
357        string (as it is for production releases) called a macro with an empty
358        argument. The C standard says the result of this is undefined. The gcc
359        compiler treats it as an empty string (which was what was wanted) but it is
360        reported that Visual C gives an error. The source has been hacked around to
361        avoid this problem.
363     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
364        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
365        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
366        of them did).
368    10. Originally, pcretest opened its input and output without "b"; then I was
369        told that "b" was needed in some environments, so it was added for release
370        5.0 to both the input and output. (It makes no difference on Unix-like
371        systems.) Later I was told that it is wrong for the input on Windows. I've
372        now abstracted the modes into two macros, to make it easier to fiddle with
373        them, and removed "b" from the input mode under Windows.
375    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
377    12. Added -help and --help to pcretest as an official way of being reminded
378        of the options.
380    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
381        and pcrecpp.cc because they annoy compilers at high warning levels.
383    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
385    15. Fixed an occurrence of == in configure.ac that should have been = (shell
386        scripts are not C programs :-) and which was not noticed because it works
387        on Linux.
389    16. pcretest is supposed to handle any length of pattern and data line (as one
390        line or as a continued sequence of lines) by extending its input buffer if
391        necessary. This feature was broken for very long pattern lines, leading to
392        a string of junk being passed to pcre_compile() if the pattern was longer
393        than about 50K.
395    17. I have done a major re-factoring of the way pcre_compile() computes the
396        amount of memory needed for a compiled pattern. Previously, there was code
397        that made a preliminary scan of the pattern in order to do this. That was
398        OK when PCRE was new, but as the facilities have expanded, it has become
399        harder and harder to keep it in step with the real compile phase, and there
400        have been a number of bugs (see for example, 4 above). I have now found a
401        cunning way of running the real compile function in a "fake" mode that
402        enables it to compute how much memory it would need, while actually only
403        ever using a few hundred bytes of working memory and without too many
404        tests of the mode. This should make future maintenance and development
405        easier. A side effect of this work is that the limit of 200 on the nesting
406        depth of parentheses has been removed (though this was never a serious
407        limitation, I suspect). However, there is a downside: pcre_compile() now
408        runs more slowly than before (30% or more, depending on the pattern). I
409        hope this isn't a big issue. There is no effect on runtime performance.
411    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
412        newline (only possible for the last line of a file) and it was a
413        pattern that set a locale (followed by /Lsomething), pcretest crashed.
415    19. Added additional timing features to pcretest. (1) The -tm option now times
416        matching only, not compiling. (2) Both -t and -tm can be followed, as a
417        separate command line item, by a number that specifies the number of
418        repeats to use when timing. The default is 50000; this gives better
419        precision, but takes uncomfortably long for very large patterns.
421    20. Extended pcre_study() to be more clever in cases where a branch of a
422        subpattern has no definite first character. For example, (a*|b*)[cd] would
423        previously give no result from pcre_study(). Now it recognizes that the
424        first character must be a, b, c, or d.
426    21. There was an incorrect error "recursive call could loop indefinitely" if
427        a subpattern (or the entire pattern) that was being tested for matching an
428        empty string contained only one non-empty item after a nested subpattern.
429        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
430        incorrectly, because the \d was being skipped in the check.
432    22. The pcretest program now has a new pattern option /B and a command line
433        option -b, which is equivalent to adding /B to every pattern. This causes
434        it to show the compiled bytecode, without the additional information that
435        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
436        is the same as /B/I).
438    23. A new optimization is now able automatically to treat some sequences such
439        as a*b as a*+b. More specifically, if something simple (such as a character
440        or a simple class like \d) has an unlimited quantifier, and is followed by
441        something that cannot possibly match the quantified thing, the quantifier
442        is automatically "possessified".
444    24. A recursive reference to a subpattern whose number was greater than 39
445        went wrong under certain circumstances in UTF-8 mode. This bug could also
446        have affected the operation of pcre_study().
448    25. Realized that a little bit of performance could be had by replacing
449        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
451    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
453    27. Possessive quantifiers such as a++ were previously implemented by turning
454        them into atomic groups such as ($>a+). Now they have their own opcodes,
455        which improves performance. This includes the automatically created ones
456        from 23 above.
458    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
459        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
460        the first matched character to be a colon. This applied both to named and
461        numbered groups.
463    29. The ucpinternal.h header file was missing its idempotency #ifdef.
465    30. I was sent a "project" file called libpcre.a.dev which I understand makes
466        building PCRE on Windows easier, so I have included it in the distribution.
468    31. There is now a check in pcretest against a ridiculously large number being
469        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
470        loop, the loop is abandoned.
472    32. Forward references to subpatterns in conditions such as (?(2)...) where
473        subpattern 2 is defined later cause pcre_compile() to search forwards in
474        the pattern for the relevant set of parentheses. This search went wrong
475        when there were unescaped parentheses in a character class, parentheses
476        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
478    33. "Subroutine" calls and backreferences were previously restricted to
479        referencing subpatterns earlier in the regex. This restriction has now
480        been removed.
482    34. Added a number of extra features that are going to be in Perl 5.10. On the
483        whole, these are just syntactic alternatives for features that PCRE had
484        previously implemented using the Python syntax or my own invention. The
485        other formats are all retained for compatibility.
487        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
488            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
489            also .NET compatible.
491        (b) A recursion or subroutine call to a named group can now be defined as
492            (?&name) as well as (?P>name).
494        (c) A backreference to a named group can now be defined as \k<name> or
495            \k'name' as well as (?P=name). The new forms, as well as being in Perl
496            5.10, are also .NET compatible.
498        (d) A conditional reference to a named group can now use the syntax
499            (?(<name>) or (?('name') as well as (?(name).
501        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
502            groups (named and numbered) that are never evaluated inline, but can be
503            called as "subroutines" from elsewhere. In effect, the DEFINE condition
504            is always false. There may be only one alternative in such a group.
506        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
507            as the simple (?(R). The condition is true only if the most recent
508            recursion is that of the given number or name. It does not search out
509            through the entire recursion stack.
511        (g) The escape \gN or \g{N} has been added, where N is a positive or
512            negative number, specifying an absolute or relative reference.
514    35. Tidied to get rid of some further signed/unsigned compiler warnings and
515        some "unreachable code" warnings.
517    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
518        things, this adds five new scripts.
520    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
521        There were also incompatibilities regarding the handling of \Q..\E inside
522        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
523        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
525    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
526        matches an empty string, and forcibly breaks the loop. There were bugs in
527        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
528        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
529        separate and independent bugs (that affected different cases) have been
530        fixed.
532    39. Refactored the code to abolish the use of different opcodes for small
533        capturing bracket numbers. This is a tidy that I avoided doing when I
534        removed the limit on the number of capturing brackets for 3.5 back in 2001.
535        The new approach is not only tidier, it makes it possible to reduce the
536        memory needed to fix the previous bug (38).
538    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
539        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
540        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
541        mode.
543    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
544        report.
546    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
547        copy construction and assignment in the C++ wrapper.
549    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
550        couple of bugs that could have given wrong results in the "--newline=crlf"
551        case.
553    44. Added a number of casts and did some reorganization of signed/unsigned int
554        variables following suggestions from Dair Grant. Also renamed the variable
555        "this" as "item" because it is a C++ keyword.
557    45. Arranged for dftables to add
559          #include "pcre_internal.h"
561        to pcre_chartables.c because without it, gcc 4.x may remove the array
562        definition from the final binary if PCRE is built into a static library and
563        dead code stripping is activated.
565    46. For an unanchored pattern, if a match attempt fails at the start of a
566        newline sequence, and the newline setting is CRLF or ANY, and the next two
567        characters are CRLF, advance by two characters instead of one.
570    Version 6.7 04-Jul-06
571    ---------------------
573     1. In order to handle tests when input lines are enormously long, pcretest has
574        been re-factored so that it automatically extends its buffers when
575        necessary. The code is crude, but this _is_ just a test program. The
576        default size has been increased from 32K to 50K.
578     2. The code in pcre_study() was using the value of the re argument before
579        testing it for NULL. (Of course, in any sensible call of the function, it
580        won't be NULL.)
582     3. The memmove() emulation function in pcre_internal.h, which is used on
583        systems that lack both memmove() and bcopy() - that is, hardly ever -
584        was missing a "static" storage class specifier.
586     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
587        containing an extended class (one that cannot be represented by a bitmap
588        because it contains high-valued characters or Unicode property items, e.g.
589        [\pZ]). Almost always one would set UTF-8 mode when processing such a
590        pattern, but PCRE should not loop if you do not (it no longer does).
591        [Detail: two cases were found: (a) a repeated subpattern containing an
592        extended class; (b) a recursive reference to a subpattern that followed a
593        previous extended class. It wasn't skipping over the extended class
594        correctly when UTF-8 mode was not set.]
596     5. A negated single-character class was not being recognized as fixed-length
597        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
598        compile error "lookbehind assertion is not fixed length".
600     6. The RunPerlTest auxiliary script was showing an unexpected difference
601        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
602        write a Perl script that can interpret lines of an input file either as
603        byte characters or as UTF-8, which is what "perltest" was being required to
604        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
605        can't do is switch easily at run time between having the "use utf8;" pragma
606        or not. In the end, I fudged it by using the RunPerlTest script to insert
607        "use utf8;" explicitly for the UTF-8 tests.
609     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
610        the end of the subject string, contrary to the documentation and to what
611        Perl does. This was true of both matching functions. Now it matches only at
612        the start of the subject and immediately after *internal* newlines.
614     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
615        a pointer to an int instead of a pointer to an unsigned long int. This
616        caused problems on 64-bit systems.
618     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
619        instance of the 'standard' template library not being so standard".
621    10. There was no check on the number of named subpatterns nor the maximum
622        length of a subpattern name. The product of these values is used to compute
623        the size of the memory block for a compiled pattern. By supplying a very
624        long subpattern name and a large number of named subpatterns, the size
625        computation could be caused to overflow. This is now prevented by limiting
626        the length of names to 32 characters, and the number of named subpatterns
627        to 10,000.
629    11. Subpatterns that are repeated with specific counts have to be replicated in
630        the compiled pattern. The size of memory for this was computed from the
631        length of the subpattern and the repeat count. The latter is limited to
632        65535, but there was no limit on the former, meaning that integer overflow
633        could in principle occur. The compiled length of a repeated subpattern is
634        now limited to 30,000 bytes in order to prevent this.
636    12. Added the optional facility to have named substrings with the same name.
638    13. Added the ability to use a named substring as a condition, using the
639        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
640        are numbers (not recommended). Forward references are permitted.
642    14. Added forward references in named backreferences (if you see what I mean).
644    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
645        pattern could run off the end of the subject. For example, the pattern
646        "(?s)(.{1,5})"8 did this with the subject "ab".
648    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
649        PCRE_CASELESS was set when matching characters that were quantified with ?
650        or *.
652    17. A character class other than a single negated character that had a minimum
653        but no maximum quantifier - for example [ab]{6,} - was not handled
654        correctly by pce_dfa_exec(). It would match only one character.
656    18. A valid (though odd) pattern that looked like a POSIX character
657        class but used an invalid character after [ (for example [[,abc,]]) caused
658        pcre_compile() to give the error "Failed: internal error: code overflow" or
659        in some cases to crash with a glibc free() error. This could even happen if
660        the pattern terminated after [[ but there just happened to be a sequence of
661        letters, a binary zero, and a closing ] in the memory that followed.
663    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
664        over the years. Originally (before any Unicode support), just the bottom 8
665        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
666        output from "man perlunicode" includes this:
668          The regular expression compiler produces polymorphic opcodes.  That
669          is, the pattern adapts to the data and automatically switches to
670          the Unicode character scheme when presented with Unicode data--or
671          instead uses a traditional byte scheme when presented with byte
672          data.
674        Sadly, a wide octal escape does not cause a switch, and in a string with
675        no other multibyte characters, these octal escapes are treated as before.
676        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
677        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
678        Unicode string.
680        I have not perpetrated such confusion in PCRE. Up till now, it took just
681        the bottom 8 bits, as in old Perl. I have now made octal escapes with
682        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
683        translate to the appropriate multibyte character.
685    29. Applied some refactoring to reduce the number of warnings from Microsoft
686        and Borland compilers. This has included removing the fudge introduced
687        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
688        a warning about an unused variable.
690    21. PCRE has not included VT (character 0x0b) in the set of whitespace
691        characters since release 4.0, because Perl (from release 5.004) does not.
692        [Or at least, is documented not to: some releases seem to be in conflict
693        with the documentation.] However, when a pattern was studied with
694        pcre_study() and all its branches started with \s, PCRE still included VT
695        as a possible starting character. Of course, this did no harm; it just
696        caused an unnecessary match attempt.
698    22. Removed a now-redundant internal flag bit that recorded the fact that case
699        dependency changed within the pattern. This was once needed for "required
700        byte" processing, but is no longer used. This recovers a now-scarce options
701        bit. Also moved the least significant internal flag bit to the most-
702        significant bit of the word, which was not previously used (hangover from
703        the days when it was an int rather than a uint) to free up another bit for
704        the future.
706    23. Added support for CRLF line endings as well as CR and LF. As well as the
707        default being selectable at build time, it can now be changed at runtime
708        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
709        specify that it is scanning data with non-default line endings.
711    24. Changed the definition of CXXLINK to make it agree with the definition of
712        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
714    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
715        recursions. This makes a big different to stack usage for some patterns.
717    26. If a subpattern containing a named recursion or subroutine reference such
718        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
719        the space required for the compiled pattern went wrong and gave too small a
720        value. Depending on the environment, this could lead to "Failed: internal
721        error: code overflow at offset 49" or "glibc detected double free or
722        corruption" errors.
724    27. Applied patches from Google (a) to support the new newline modes and (b) to
725        advance over multibyte UTF-8 characters in GlobalReplace.
727    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
728        difference for some implementation of PCRE in some Windows version.
730    29. Added some extra testing facilities to pcretest:
732        \q<number>   in a data line sets the "match limit" value
733        \Q<number>   in a data line sets the "match recursion limt" value
734        -S <number>  sets the stack size, where <number> is in megabytes
736        The -S option isn't available for Windows.
739  Version 6.6 06-Feb-06  Version 6.6 06-Feb-06
740  ---------------------  ---------------------

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