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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.9 xx-xxx-09
5    ---------------------
7    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
8        (pcretest), all targets were linked against these libraries. This included
9        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
10        libraries. This caused unwanted dependencies to be created. This problem
11        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
12        pcretest is linked with readline.
14    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
15        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
16        moved outside it again, because FALSE and TRUE are already defined in AIX,
17        but BOOL is not.
19    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
20        PCRE_MATCH_LIMIT_RETURSION values as ints, when they should be long ints.
22    4.  The pcregrep documentation said spaces were inserted as well as colons (or
23        hyphens) following file names and line numbers when outputting matching
24        lines. This is not true; no spaces are inserted. I have also clarified the
25        wording for the --colour (or --color) option.
27    5.  In pcregrep, when --colour was used with -o, the list of matching strings
28        was not coloured; this is different to GNU grep, so I have changed it to be
29        the same.
31    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
32        each matching line was coloured. Now it goes on to look for further matches
33        of any of the test patterns, which is the same behaviour as GNU grep.
35    7.  A pattern that could match an empty string could cause pcregrep to loop; it
36        doesn't make sense to accept an empty string match in pcregrep, so I have
37        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
38        seems to be how GNU grep behaves.
40    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
41        start or after a newline", because the conditional assertion was not being
42        correctly handled. The rule now is that both the assertion and what follows
43        in the first alternative must satisfy the test.
45    9.  If auto-callout was enabled in a pattern with a conditional group whose
46        condition was an assertion, PCRE could crash during matching, both with
47        pcre_exec() and pcre_dfa_exec().
49    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
50        used for matching.
52    11. Unicode property support in character classes was not working for
53        characters (bytes) greater than 127 when not in UTF-8 mode.
55    12. Added the -M command line option to pcretest.
57    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
59    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
61    16. Added comments and documentation about mis-use of no_arg in the C++
62        wrapper.
64    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
65        from Martin Jerabek that uses macro names for all relevant character and
66        string constants.
68    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
69        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
70        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
71        these, but not everybody uses configure.
73    19. A conditional group that had only one branch was not being correctly
74        recognized as an item that could match an empty string. This meant that an
75        enclosing group might also not be so recognized, causing infinite looping
76        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
77        with the subject "ab", where knowledge that the repeated group can match
78        nothing is needed in order to break the loop.
80    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
81        exec(), but without supplying a callout function, matching went wrong.
84    Version 7.8 05-Sep-08
85    ---------------------
87    1.  Replaced UCP searching code with optimized version as implemented for Ad
88        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
89        stage table and inline lookup instead of a function, giving speed ups of 2
90        to 5 times on some simple patterns that I tested. Permission was given to
91        distribute the MultiStage2.py script that generates the tables (it's not in
92        the tarball, but is in the Subversion repository).
94    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
95        scripts.
97    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
98        a group with a zero qualifier. The result of the study could be incorrect,
99        or the function might crash, depending on the pattern.
101    4.  Caseless matching was not working for non-ASCII characters in back
102        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
103        It now works when Unicode Property Support is available.
105    5.  In pcretest, an escape such as \x{de} in the data was always generating
106        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
107        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
108        truncation.
110    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
112    7.  Added two (int) casts to pcregrep when printing the difference of two
113        pointers, in case they are 64-bit values.
115    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
116        test 2 if it fails.
118    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
119        and a #define of that name to empty if it is not externally set. This is to
120        allow users of MSVC to set it if necessary.
122    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
123        the convenience functions in the pcre_get.c source file.
125    11. An option change at the start of a pattern that had top-level alternatives
126        could cause overwriting and/or a crash. This command provoked a crash in
127        some environments:
129          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
131        This potential security problem was recorded as CVE-2008-2371.
133    12. For a pattern where the match had to start at the beginning or immediately
134        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
135        pcre_dfa_exec() could read past the end of the passed subject if there was
136        no match. To help with detecting such bugs (e.g. with valgrind), I modified
137        pcretest so that it places the subject at the end of its malloc-ed buffer.
139    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
140        exec() might read past the end of the data buffer in UTF-8 mode.
142    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
143        the data contained the byte 0x85 as part of a UTF-8 character within its
144        first line. This applied both to normal and DFA matching.
146    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
147        /^[^d]*?$/8 failed to match "abc".
149    16. Added a missing copyright notice to pcrecpp_internal.h.
151    17. Make it more clear in the documentation that values returned from
152        pcre_exec() in ovector are byte offsets, not character counts.
154    18. Tidied a few places to stop certain compilers from issuing warnings.
156    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
157        supplied by Stefan Weber. I made a further small update for 7.8 because
158        there is a change of source arrangements: the pcre_searchfuncs.c module is
159        replaced by pcre_ucd.c.
162    Version 7.7 07-May-08
163    ---------------------
165    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
166        a string to a long long, pretend we don't even have a long long." This is
167        done by checking for the strtoq, strtoll, and _strtoi64 functions.
169    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
170        pre-7.6 versions, which defined a global no_arg variable instead of putting
171        it in the RE class. (See also #8 below.)
173    3.  Remove a line of dead code, identified by coverity and reported by Nuno
174        Lopes.
176    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
178        (1) The include/exclude patterns were being applied to the whole pathnames
179            of files, instead of just to the final components.
181        (2) If there was more than one level of directory, the subdirectories were
182            skipped unless they satisfied the include/exclude conditions. This is
183            inconsistent with GNU grep (and could even be seen as contrary to the
184            pcregrep specification - which I improved to make it absolutely clear).
185            The action now is always to scan all levels of directory, and just
186            apply the include/exclude patterns to regular files.
188    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
189        --exclude_dir in the tests to avoid scanning .svn directories.
191    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
192        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
193        doesn't support NULs in patterns.
195    7.  Added some missing "const"s to declarations of static tables in
196        pcre_compile.c and pcre_dfa_exec.c.
198    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
199        caused by fix #2  above. (Subsequently also a second patch to fix the
200        first patch. And a third patch - this was a messy problem.)
202    9.  Applied Craig's patch to remove the use of push_back().
204    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
205        matching function regexec().
207    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
208        which, however, unlike Perl's \g{...}, are subroutine calls, not back
209        references. PCRE supports relative numbers with this syntax (I don't think
210        Oniguruma does).
212    12. Previously, a group with a zero repeat such as (...){0} was completely
213        omitted from the compiled regex. However, this means that if the group
214        was called as a subroutine from elsewhere in the pattern, things went wrong
215        (an internal error was given). Such groups are now left in the compiled
216        pattern, with a new opcode that causes them to be skipped at execution
217        time.
219    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
220        to the way PCRE behaves:
222        (a) A lone ] character is dis-allowed (Perl treats it as data).
224        (b) A back reference to an unmatched subpattern matches an empty string
225            (Perl fails the current match path).
227        (c) A data ] in a character class must be notated as \] because if the
228            first data character in a class is ], it defines an empty class. (In
229            Perl it is not possible to have an empty class.) The empty class []
230            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
231            The negative empty class [^] matches any one character, independently
232            of the DOTALL setting.
234    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
235        non-existent subpattern following a character class starting with ']' and
236        containing () gave an internal compiling error instead of "reference to
237        non-existent subpattern". Fortunately, when the pattern did exist, the
238        compiled code was correct. (When scanning forwards to check for the
239        existencd of the subpattern, it was treating the data ']' as terminating
240        the class, so got the count wrong. When actually compiling, the reference
241        was subsequently set up correctly.)
243    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
244        it was being rejected as not supported by pcre_dfa_exec(), even though
245        other assertions are supported. I have made pcre_dfa_exec() support
246        (*FAIL).
248    16. The implementation of 13c above involved the invention of a new opcode,
249        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
250        cannot be changed at match time, I realized I could make a small
251        improvement to matching performance by compiling OP_ALLANY instead of
252        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
253        on the OP_ANY path.
255    17. Compiling pcretest on Windows with readline support failed without the
256        following two fixes: (1) Make the unistd.h include conditional on
257        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
259    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
260        ncurses library to be included for pcretest when ReadLine support is
261        requested, but also to allow for it to be overridden. This patch came from
262        Daniel Bergström.
264    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
265        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
266        any errors with the current Unicode tables. Thanks to Peter Kankowski for
267        spotting this.
270    Version 7.6 28-Jan-08
271    ---------------------
273    1.  A character class containing a very large number of characters with
274        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
275        overflow.
277    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
278        HAVE_LONG_LONG is not defined.
280    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
281        bring them up to date and include new features. This patch includes:
283        - Fixed PH's badly added libz and libbz2 support.
284        - Fixed a problem with static linking.
285        - Added pcredemo. [But later removed - see 7 below.]
286        - Fixed dftables problem and added an option.
287        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
288            HAVE_LONG_LONG.
289        - Added readline support for pcretest.
290        - Added an listing of the option settings after cmake has run.
292    4.  A user submitted a patch to Makefile that makes it easy to create
293        "pcre.dll" under mingw when using Configure/Make. I added stuff to
294        Makefile.am that cause it to include this special target, without
295        affecting anything else. Note that the same mingw target plus all
296        the other distribution libraries and programs are now supported
297        when configuring with CMake (see 6 below) instead of with
298        Configure/Make.
300    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
301        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
302        exported in the Windows port". It has not yet been confirmed that the patch
303        solves the problem, but it does no harm.
305    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
306        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
307        with CMake, and also correct the comment about stack recursion.
309    7.  Remove the automatic building of pcredemo from the ./configure system and
310        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
311        of a program that users should build themselves after PCRE is installed, so
312        building it automatically is not really right. What is more, it gave
313        trouble in some build environments.
315    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
318    Version 7.5 10-Jan-08
319    ---------------------
321    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
322        values in parens when parsing an RE using the C++ wrapper."
324    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
325        Characters greater than 255 were excluded from the class instead of being
326        included.
328    3.  The same bug as (2) above applied to negated POSIX classes such as
329        [:^space:].
331    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
332        defined or documented. It seems to have been a typo for PCRE_STATIC, so
333        I have changed it.
335    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
336        first named subpattern) and a construct such as (?&a) would reference the
337        first named subpattern whose name started with "a" (in other words, the
338        length check was missing). Both these problems are fixed. "Subpattern name
339        expected" is now given for (?&) (a zero-length name), and this patch also
340        makes it give the same error for \k'' (previously it complained that that
341        was a reference to a non-existent subpattern).
343    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
344        this is right because (?- can be followed by option settings as well as by
345        digits. I have, however, made the messages clearer.
347    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
348        than the number used in the conditional) now cause a compile-time error.
349        This is actually not compatible with Perl, which accepts such patterns, but
350        treats the conditional as always being FALSE (as PCRE used to), but it
351        seems to me that giving a diagnostic is better.
353    8.  Change "alphameric" to the more common word "alphanumeric" in comments
354        and messages.
356    9.  Fix two occurrences of "backslash" in comments that should have been
357        "backspace".
359    10. Remove two redundant lines of code that can never be obeyed (their function
360        was moved elsewhere).
362    11. The program that makes PCRE's Unicode character property table had a bug
363        which caused it to generate incorrect table entries for sequences of
364        characters that have the same character type, but are in different scripts.
365        It amalgamated them into a single range, with the script of the first of
366        them. In other words, some characters were in the wrong script. There were
367        thirteen such cases, affecting characters in the following ranges:
369          U+002b0 - U+002c1
370          U+0060c - U+0060d
371          U+0061e - U+00612
372          U+0064b - U+0065e
373          U+0074d - U+0076d
374          U+01800 - U+01805
375          U+01d00 - U+01d77
376          U+01d9b - U+01dbf
377          U+0200b - U+0200f
378          U+030fc - U+030fe
379          U+03260 - U+0327f
380          U+0fb46 - U+0fbb1
381          U+10450 - U+1049d
383    12. The -o option (show only the matching part of a line) for pcregrep was not
384        compatible with GNU grep in that, if there was more than one match in a
385        line, it showed only the first of them. It now behaves in the same way as
386        GNU grep.
388    13. If the -o and -v options were combined for pcregrep, it printed a blank
389        line for every non-matching line. GNU grep prints nothing, and pcregrep now
390        does the same. The return code can be used to tell if there were any
391        non-matching lines.
393    14. Added --file-offsets and --line-offsets to pcregrep.
395    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
396        infinitely looping recursion. The bug was that positive lookaheads were not
397        being skipped when checking for a possible empty match (negative lookaheads
398        and both kinds of lookbehind were skipped).
400    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
401        inclusion of <windows.h> to before rather than after the definition of
402        INVALID_FILE_ATTRIBUTES (patch from David Byron).
404    17. Specifying a possessive quantifier with a specific limit for a Unicode
405        character property caused pcre_compile() to compile bad code, which led at
406        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
407        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
408        caused the error; without that there was no problem.
410    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
412    19. Added --enable-pcretest-libreadline.
414    20. In pcrecpp.cc, the variable 'count' was incremented twice in
415        RE::GlobalReplace(). As a result, the number of replacements returned was
416        double what it should be. I removed one of the increments, but Craig sent a
417        later patch that removed the other one (the right fix) and added unit tests
418        that check the return values (which was not done before).
420    21. Several CMake things:
422        (1) Arranged that, when cmake is used on Unix, the libraries end up with
423            the names libpcre and libpcreposix, not just pcre and pcreposix.
425        (2) The above change means that pcretest and pcregrep are now correctly
426            linked with the newly-built libraries, not previously installed ones.
430    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
431        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
432        UTF-8 newline character). The key issue is that the pattern starts .*;
433        this means that the match must be either at the beginning, or after a
434        newline. The bug was in the code for advancing after a failed match and
435        checking that the new position followed a newline. It was not taking
436        account of UTF-8 characters correctly.
438    23. PCRE was behaving differently from Perl in the way it recognized POSIX
439        character classes. PCRE was not treating the sequence [:...:] as a
440        character class unless the ... were all letters. Perl, however, seems to
441        allow any characters between [: and :], though of course it rejects as
442        unknown any "names" that contain non-letters, because all the known class
443        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
444        for example, whereas PCRE did not - it did not recognize a POSIX character
445        class. This seemed a bit dangerous, so the code has been changed to be
446        closer to Perl. The behaviour is not identical to Perl, because PCRE will
447        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
448        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
449        Perl does, and where it didn't before.
451    24. Rewrite so as to remove the single use of %n from pcregrep because in some
452        Windows environments %n is disabled by default.
455    Version 7.4 21-Sep-07
456    ---------------------
458    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
459        means that a class such as [\s] counted as "explicit reference to CR or
460        LF". That isn't really right - the whole point of the change was to try to
461        help when there was an actual mention of one of the two characters. So now
462        the change happens only if \r or \n (or a literal CR or LF) character is
463        encountered.
465    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
466        of both had grown to the point where there were only 3 bits left.
467        Fortunately, there was spare space in the data structure, and so I have
468        moved the internal flags into a new 16-bit field to free up more option
469        bits.
471    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
472        but did not set the internal JCHANGED flag - either of these is enough to
473        control the way the "get" function works - but the PCRE_INFO_JCHANGED
474        facility is supposed to tell if (?J) was ever used, so now (?J) at the
475        start sets both bits.
477    4.  Added options (at build time, compile time, exec time) to change \R from
478        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
480    5.  doc/pcresyntax.html was missing from the distribution.
482    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
483        compatibility, even though it is no longer used.
485    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
486        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
487        windows.h file is present (where different names are used). [This was
488        reversed later after testing - see 16 below.]
490    8.  Changed all #include <config.h> to #include "config.h". There were also
491        some further <pcre.h> cases that I changed to "pcre.h".
493    9.  When pcregrep was used with the --colour option, it missed the line ending
494        sequence off the lines that it output.
496    10. It was pointed out to me that arrays of string pointers cause lots of
497        relocations when a shared library is dynamically loaded. A technique of
498        using a single long string with a table of offsets can drastically reduce
499        these. I have refactored PCRE in four places to do this. The result is
500        dramatic:
502          Originally:                          290
503          After changing UCP table:            187
504          After changing error message table:   43
505          After changing table of "verbs"       36
506          After changing table of Posix names   22
508        Thanks to the folks working on Gregex for glib for this insight.
510    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
511        unicode-properties was also set.
513    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
515    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
516        checked only for CRLF.
518    14. Added casts to pcretest.c to avoid compiler warnings.
520    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
522    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
523        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
524        entirely. This removes changes made in 7 above.
526    17. The CMake files have been updated, and there is now more information about
527        building with CMake in the NON-UNIX-USE document.
530    Version 7.3 28-Aug-07
531    ---------------------
533     1. In the rejigging of the build system that eventually resulted in 7.1, the
534        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
535        brackets there is not right, since it causes compilers to look for an
536        installed pcre.h, not the version that is in the source that is being
537        compiled (which of course may be different). I have changed it back to:
539          #include "pcre.h"
541        I have a vague recollection that the change was concerned with compiling in
542        different directories, but in the new build system, that is taken care of
543        by the VPATH setting the Makefile.
545     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
546        when the subject happened to end in the byte 0x85 (e.g. if the last
547        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
548        characters but of course it shouldn't be taken as a newline when it is part
549        of another character. The bug was that, for an unlimited repeat of . in
550        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
551        characters when looking for a newline.
553     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
555     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
556        in debug output.
558     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
559        long printing in the pcrecpp unittest when running under MinGW.
561     6. ESC_K was left out of the EBCDIC table.
563     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
564        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
565        limit also applies to "virtual nesting" when a pattern is recursive, and in
566        this case 1000 isn't so big. I have been able to remove this limit at the
567        expense of backing off one optimization in certain circumstances. Normally,
568        when pcre_exec() would call its internal match() function recursively and
569        immediately return the result unconditionally, it uses a "tail recursion"
570        feature to save stack. However, when a subpattern that can match an empty
571        string has an unlimited repetition quantifier, it no longer makes this
572        optimization. That gives it a stack frame in which to save the data for
573        checking that an empty string has been matched. Previously this was taken
574        from the 1000-entry workspace that had been reserved. So now there is no
575        explicit limit, but more stack is used.
577     8. Applied Daniel's patches to solve problems with the import/export magic
578        syntax that is required for Windows, and which was going wrong for the
579        pcreposix and pcrecpp parts of the library. These were overlooked when this
580        problem was solved for the main library.
582     9. There were some crude static tests to avoid integer overflow when computing
583        the size of patterns that contain repeated groups with explicit upper
584        limits. As the maximum quantifier is 65535, the maximum group length was
585        set at 30,000 so that the product of these two numbers did not overflow a
586        32-bit integer. However, it turns out that people want to use groups that
587        are longer than 30,000 bytes (though not repeat them that many times).
588        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
589        made it possible to implement the integer overflow checks in a much more
590        dynamic way, which I have now done. The artificial limitation on group
591        length has been removed - we now have only the limit on the total length of
592        the compiled pattern, which depends on the LINK_SIZE setting.
594    10. Fixed a bug in the documentation for get/copy named substring when
595        duplicate names are permitted. If none of the named substrings are set, the
596        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
597        empty string.
599    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
600        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
601        because the ] is interpreted as the first data character and the
602        terminating ] is not found. PCRE has been made compatible with Perl in this
603        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
604        cause memory overwriting.
606    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
607        string has been matched (to stop an infinite loop). It was not recognizing
608        a conditional subpattern that could match an empty string if that
609        subpattern was within another subpattern. For example, it looped when
610        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
611        condition was not nested. This bug has been fixed.
613    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
614        past the start of the subject in the presence of bytes with the top bit
615        set, for example "\x8aBCD".
617    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
618        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
620    14. Optimized (?!) to (*FAIL).
622    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
623        This restricts code points to be within the range 0 to 0x10FFFF, excluding
624        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
625        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
626        does: it's just the validity check that is more restrictive.
628    16. Inserted checks for integer overflows during escape sequence (backslash)
629        processing, and also fixed erroneous offset values for syntax errors during
630        backslash processing.
632    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
633        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
635    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
636        caused an overrun.
638    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
639        something other than just ASCII characters) inside a group that had an
640        unlimited repeat caused a loop at compile time (while checking to see
641        whether the group could match an empty string).
643    20. Debugging a pattern containing \p or \P could cause a crash. For example,
644        [\P{Any}] did so. (Error in the code for printing property names.)
646    21. An orphan \E inside a character class could cause a crash.
648    22. A repeated capturing bracket such as (A)? could cause a wild memory
649        reference during compilation.
651    23. There are several functions in pcre_compile() that scan along a compiled
652        expression for various reasons (e.g. to see if it's fixed length for look
653        behind). There were bugs in these functions when a repeated \p or \P was
654        present in the pattern. These operators have additional parameters compared
655        with \d, etc, and these were not being taken into account when moving along
656        the compiled data. Specifically:
658        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
659            length.
661        (b) An item such as \pL+ within a repeated group could cause crashes or
662            loops.
664        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
665            "reference to non-existent subpattern" error.
667        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
669    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
670        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
672    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
674    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
675        character were causing crashes (broken optimization).
677    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
678        \p or \P) caused a compile-time loop.
680    28. More problems have arisen in unanchored patterns when CRLF is a valid line
681        break. For example, the unstudied pattern [\r\n]A does not match the string
682        "\r\nA" because change 7.0/46 below moves the current point on by two
683        characters after failing to match at the start. However, the pattern \nA
684        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
685        the same is true. There doesn't seem any very clean way out of this, but
686        what I have chosen to do makes the common cases work: PCRE now takes note
687        of whether there can be an explicit match for \r or \n anywhere in the
688        pattern, and if so, 7.0/46 no longer applies. As part of this change,
689        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
690        pattern has explicit CR or LF references.
692    29. Added (*CR) etc for changing newline setting at start of pattern.
695    Version 7.2 19-Jun-07
696    ---------------------
698     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
699        which is apparently normally available under Windows.
701     2. Re-jig the pcregrep tests with different newline settings in an attempt
702        to make them independent of the local environment's newline setting.
704     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
706     4. Some of the "internals" tests were previously cut out when the link size
707        was not 2, because the output contained actual offsets. The recent new
708        "Z" feature of pcretest means that these can be cut out, making the tests
709        usable with all link sizes.
711     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
712        stack recursion. This gives a massive performance boost under BSD, but just
713        a small improvement under Linux. However, it saves one field in the frame
714        in all cases.
716     6. Added more features from the forthcoming Perl 5.10:
718        (a) (?-n) (where n is a string of digits) is a relative subroutine or
719            recursion call. It refers to the nth most recently opened parentheses.
721        (b) (?+n) is also a relative subroutine call; it refers to the nth next
722            to be opened parentheses.
724        (c) Conditions that refer to capturing parentheses can be specified
725            relatively, for example, (?(-2)... or (?(+3)...
727        (d) \K resets the start of the current match so that everything before
728            is not part of it.
730        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
732        (f) \g{name} is another synonym - part of Perl 5.10's unification of
733            reference syntax.
735        (g) (?| introduces a group in which the numbering of parentheses in each
736            alternative starts with the same number.
738        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
740     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
743     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
744        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
745        for detecting groups that can match an empty string.
747     9. A pattern with a very large number of alternatives (more than several
748        hundred) was running out of internal workspace during the pre-compile
749        phase, where pcre_compile() figures out how much memory will be needed. A
750        bit of new cunning has reduced the workspace needed for groups with
751        alternatives. The 1000-alternative test pattern now uses 12 bytes of
752        workspace instead of running out of the 4096 that are available.
754    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
756    11. Applied patch from Google to remove an optimization that didn't quite work.
757        The report of the bug said:
759          pcrecpp::RE("a*").FullMatch("aaa") matches, while
760          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
761          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
763    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
764        it matched the wrong number of bytes.
767    Version 7.1 24-Apr-07
768    ---------------------
770     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
771        that is more "standard", making use of automake and other Autotools. There
772        is some re-arrangement of the files and adjustment of comments consequent
773        on this.
775     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
776        for recursive directory scanning broke on some systems because the files
777        are not scanned in any specific order and on different systems the order
778        was different. A call to "sort" has been inserted into RunGrepTest for the
779        approprate test as a short-term fix. In the longer term there may be an
780        alternative.
782     3. I had an email from Eric Raymond about problems translating some of PCRE's
783        man pages to HTML (despite the fact that I distribute HTML pages, some
784        people do their own conversions for various reasons). The problems
785        concerned the use of low-level troff macros .br and .in. I have therefore
786        removed all such uses from the man pages (some were redundant, some could
787        be replaced by .nf/.fi pairs). The 132html script that I use to generate
788        HTML has been updated to handle .nf/.fi and to complain if it encounters
789        .br or .in.
791     4. Updated comments in configure.ac that get placed in config.h.in and also
792        arranged for config.h to be included in the distribution, with the name
793        config.h.generic, for the benefit of those who have to compile without
794        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
796     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
797        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
798        makevp.bat for the current PCRE, using the additional files
799        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
801     6. A Windows user reported a minor discrepancy with test 2, which turned out
802        to be caused by a trailing space on an input line that had got lost in his
803        copy. The trailing space was an accident, so I've just removed it.
805     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
806        that is needed.
808     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
809        as "const" (a) because they are and (b) because it helps the PHP
810        maintainers who have recently made a script to detect big data structures
811        in the php code that should be moved to the .rodata section. I remembered
812        to update Builducptable as well, so it won't revert if ucptable.h is ever
813        re-created.
815     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
816        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
817        order to be able to cut out the UTF-8 tables in the latter when UTF-8
818        support is not required. This saves 1.5-2K of code, which is important in
819        some applications.
821        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
822        so as not to refer to the tables, even though these functions will never be
823        called when UTF-8 support is disabled. Otherwise there are problems with a
824        shared library.
826    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
828        (a) It was defining its arguments as char * instead of void *.
830        (b) It was assuming that all moves were upwards in memory; this was true
831            a long time ago when I wrote it, but is no longer the case.
833        The emulated memove() is provided for those environments that have neither
834        memmove() nor bcopy(). I didn't think anyone used it these days, but that
835        is clearly not the case, as these two bugs were recently reported.
837    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
838        and Detrail to create the HTML documentation, the .txt form of the man
839        pages, and it removes trailing spaces from listed files. It also creates
840        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
841        case, it wraps all the #defines with #ifndefs. This script should be run
842        before "make dist".
844    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
845        with Unicode property support.
847        (a) For a maximizing quantifier, if the two different cases of the
848            character were of different lengths in their UTF-8 codings (there are
849            some cases like this - I found 11), and the matching function had to
850            back up over a mixture of the two cases, it incorrectly assumed they
851            were both the same length.
853        (b) When PCRE was configured to use the heap rather than the stack for
854            recursion during matching, it was not correctly preserving the data for
855            the other case of a UTF-8 character when checking ahead for a match
856            while processing a minimizing repeat. If the check also involved
857            matching a wide character, but failed, corruption could cause an
858            erroneous result when trying to check for a repeat of the original
859            character.
861    13. Some tidying changes to the testing mechanism:
863        (a) The RunTest script now detects the internal link size and whether there
864            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
865            values substituted by "configure". (The RunGrepTest script already did
866            this for UTF-8.) The configure.ac script no longer substitutes the
867            relevant variables.
869        (b) The debugging options /B and /D in pcretest show the compiled bytecode
870            with length and offset values. This means that the output is different
871            for different internal link sizes. Test 2 is skipped for link sizes
872            other than 2 because of this, bypassing the problem. Unfortunately,
873            there was also a test in test 3 (the locale tests) that used /B and
874            failed for link sizes other than 2. Rather than cut the whole test out,
875            I have added a new /Z option to pcretest that replaces the length and
876            offset values with spaces. This is now used to make test 3 independent
877            of link size. (Test 2 will be tidied up later.)
879    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
880        segmentation fault instead of returning the appropriate error message.
882    15. In multiline mode when the newline sequence was set to "any", the pattern
883        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
884        This doesn't seem right; it now treats the CRLF combination as the line
885        ending, and so does not match in that case. It's only a pattern such as ^$
886        that would hit this one: something like ^ABC$ would have failed after \r
887        and then tried again after \r\n.
889    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
890        in an attempt to make files that differ only in their line terminators
891        compare equal. This works on Linux.
893    17. Under certain error circumstances pcregrep might try to free random memory
894        as it exited. This is now fixed, thanks to valgrind.
896    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
897        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
898        was because its rules for how to advance for /g after matching an empty
899        string at the end of a line did not allow for this case. They now check for
900        it specially.
902    20. pcretest is supposed to handle patterns and data of any length, by
903        extending its buffers when necessary. It was getting this wrong when the
904        buffer for a data line had to be extended.
906    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
907        CRLF as a newline sequence.
909    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
910        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
911        I have nevertheless tidied it up.
913    23. Added some casts to kill warnings from HP-UX ia64 compiler.
915    24. Added a man page for pcre-config.
918    Version 7.0 19-Dec-06
919    ---------------------
921     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
922        moving to gcc 4.1.1.
924     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
925        sys/time.h, which is documented as needed for this function. It doesn't
926        seem to matter on Linux, but it showed up on some releases of OS X.
928     3. It seems that there are systems where bytes whose values are greater than
929        127 match isprint() in the "C" locale. The "C" locale should be the
930        default when a C program starts up. In most systems, only ASCII printing
931        characters match isprint(). This difference caused the output from pcretest
932        to vary, making some of the tests fail. I have changed pcretest so that:
934        (a) When it is outputting text in the compiled version of a pattern, bytes
935            other than 32-126 are always shown as hex escapes.
937        (b) When it is outputting text that is a matched part of a subject string,
938            it does the same, unless a different locale has been set for the match
939            (using the /L modifier). In this case, it uses isprint() to decide.
941     4. Fixed a major bug that caused incorrect computation of the amount of memory
942        required for a compiled pattern when options that changed within the
943        pattern affected the logic of the preliminary scan that determines the
944        length. The relevant options are -x, and -i in UTF-8 mode. The result was
945        that the computed length was too small. The symptoms of this bug were
946        either the PCRE error "internal error: code overflow" from pcre_compile(),
947        or a glibc crash with a message such as "pcretest: free(): invalid next
948        size (fast)". Examples of patterns that provoked this bug (shown in
949        pcretest format) are:
951          /(?-x: )/x
952          /(?x)(?-x: \s*#\s*)/
953          /((?i)[\x{c0}])/8
954          /(?i:[\x{c0}])/8
956        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
957        is now done differently.
959     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
960        wrapper classes; (b) implement a new function in the C++ scanner that is
961        more efficient than the old way of doing things because it avoids levels of
962        recursion in the regex matching; (c) add a paragraph to the documentation
963        for the FullMatch() function.
965     6. The escape sequence \n was being treated as whatever was defined as
966        "newline". Not only was this contrary to the documentation, which states
967        that \n is character 10 (hex 0A), but it also went horribly wrong when
968        "newline" was defined as CRLF. This has been fixed.
970     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
971        was being set to -1 for the "end of line" case (supposedly a value that no
972        character can have). Though this value is never used (the check for end of
973        line is "zero bytes in current character"), it caused compiler complaints.
974        I've changed it to 0xffffffff.
976     8. In pcre_version.c, the version string was being built by a sequence of
977        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
978        string (as it is for production releases) called a macro with an empty
979        argument. The C standard says the result of this is undefined. The gcc
980        compiler treats it as an empty string (which was what was wanted) but it is
981        reported that Visual C gives an error. The source has been hacked around to
982        avoid this problem.
984     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
985        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
986        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
987        of them did).
989    10. Originally, pcretest opened its input and output without "b"; then I was
990        told that "b" was needed in some environments, so it was added for release
991        5.0 to both the input and output. (It makes no difference on Unix-like
992        systems.) Later I was told that it is wrong for the input on Windows. I've
993        now abstracted the modes into two macros, to make it easier to fiddle with
994        them, and removed "b" from the input mode under Windows.
996    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
998    12. Added -help and --help to pcretest as an official way of being reminded
999        of the options.
1001    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
1002        and pcrecpp.cc because they annoy compilers at high warning levels.
1004    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
1006    15. Fixed an occurrence of == in configure.ac that should have been = (shell
1007        scripts are not C programs :-) and which was not noticed because it works
1008        on Linux.
1010    16. pcretest is supposed to handle any length of pattern and data line (as one
1011        line or as a continued sequence of lines) by extending its input buffer if
1012        necessary. This feature was broken for very long pattern lines, leading to
1013        a string of junk being passed to pcre_compile() if the pattern was longer
1014        than about 50K.
1016    17. I have done a major re-factoring of the way pcre_compile() computes the
1017        amount of memory needed for a compiled pattern. Previously, there was code
1018        that made a preliminary scan of the pattern in order to do this. That was
1019        OK when PCRE was new, but as the facilities have expanded, it has become
1020        harder and harder to keep it in step with the real compile phase, and there
1021        have been a number of bugs (see for example, 4 above). I have now found a
1022        cunning way of running the real compile function in a "fake" mode that
1023        enables it to compute how much memory it would need, while actually only
1024        ever using a few hundred bytes of working memory and without too many
1025        tests of the mode. This should make future maintenance and development
1026        easier. A side effect of this work is that the limit of 200 on the nesting
1027        depth of parentheses has been removed (though this was never a serious
1028        limitation, I suspect). However, there is a downside: pcre_compile() now
1029        runs more slowly than before (30% or more, depending on the pattern). I
1030        hope this isn't a big issue. There is no effect on runtime performance.
1032    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
1033        newline (only possible for the last line of a file) and it was a
1034        pattern that set a locale (followed by /Lsomething), pcretest crashed.
1036    19. Added additional timing features to pcretest. (1) The -tm option now times
1037        matching only, not compiling. (2) Both -t and -tm can be followed, as a
1038        separate command line item, by a number that specifies the number of
1039        repeats to use when timing. The default is 50000; this gives better
1040        precision, but takes uncomfortably long for very large patterns.
1042    20. Extended pcre_study() to be more clever in cases where a branch of a
1043        subpattern has no definite first character. For example, (a*|b*)[cd] would
1044        previously give no result from pcre_study(). Now it recognizes that the
1045        first character must be a, b, c, or d.
1047    21. There was an incorrect error "recursive call could loop indefinitely" if
1048        a subpattern (or the entire pattern) that was being tested for matching an
1049        empty string contained only one non-empty item after a nested subpattern.
1050        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
1051        incorrectly, because the \d was being skipped in the check.
1053    22. The pcretest program now has a new pattern option /B and a command line
1054        option -b, which is equivalent to adding /B to every pattern. This causes
1055        it to show the compiled bytecode, without the additional information that
1056        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
1057        is the same as /B/I).
1059    23. A new optimization is now able automatically to treat some sequences such
1060        as a*b as a*+b. More specifically, if something simple (such as a character
1061        or a simple class like \d) has an unlimited quantifier, and is followed by
1062        something that cannot possibly match the quantified thing, the quantifier
1063        is automatically "possessified".
1065    24. A recursive reference to a subpattern whose number was greater than 39
1066        went wrong under certain circumstances in UTF-8 mode. This bug could also
1067        have affected the operation of pcre_study().
1069    25. Realized that a little bit of performance could be had by replacing
1070        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
1072    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
1074    27. Possessive quantifiers such as a++ were previously implemented by turning
1075        them into atomic groups such as ($>a+). Now they have their own opcodes,
1076        which improves performance. This includes the automatically created ones
1077        from 23 above.
1079    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
1080        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
1081        the first matched character to be a colon. This applied both to named and
1082        numbered groups.
1084    29. The ucpinternal.h header file was missing its idempotency #ifdef.
1086    30. I was sent a "project" file called libpcre.a.dev which I understand makes
1087        building PCRE on Windows easier, so I have included it in the distribution.
1089    31. There is now a check in pcretest against a ridiculously large number being
1090        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
1091        loop, the loop is abandoned.
1093    32. Forward references to subpatterns in conditions such as (?(2)...) where
1094        subpattern 2 is defined later cause pcre_compile() to search forwards in
1095        the pattern for the relevant set of parentheses. This search went wrong
1096        when there were unescaped parentheses in a character class, parentheses
1097        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
1099    33. "Subroutine" calls and backreferences were previously restricted to
1100        referencing subpatterns earlier in the regex. This restriction has now
1101        been removed.
1103    34. Added a number of extra features that are going to be in Perl 5.10. On the
1104        whole, these are just syntactic alternatives for features that PCRE had
1105        previously implemented using the Python syntax or my own invention. The
1106        other formats are all retained for compatibility.
1108        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
1109            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
1110            also .NET compatible.
1112        (b) A recursion or subroutine call to a named group can now be defined as
1113            (?&name) as well as (?P>name).
1115        (c) A backreference to a named group can now be defined as \k<name> or
1116            \k'name' as well as (?P=name). The new forms, as well as being in Perl
1117            5.10, are also .NET compatible.
1119        (d) A conditional reference to a named group can now use the syntax
1120            (?(<name>) or (?('name') as well as (?(name).
1122        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
1123            groups (named and numbered) that are never evaluated inline, but can be
1124            called as "subroutines" from elsewhere. In effect, the DEFINE condition
1125            is always false. There may be only one alternative in such a group.
1127        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
1128            as the simple (?(R). The condition is true only if the most recent
1129            recursion is that of the given number or name. It does not search out
1130            through the entire recursion stack.
1132        (g) The escape \gN or \g{N} has been added, where N is a positive or
1133            negative number, specifying an absolute or relative reference.
1135    35. Tidied to get rid of some further signed/unsigned compiler warnings and
1136        some "unreachable code" warnings.
1138    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
1139        things, this adds five new scripts.
1141    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
1142        There were also incompatibilities regarding the handling of \Q..\E inside
1143        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
1144        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
1146    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
1147        matches an empty string, and forcibly breaks the loop. There were bugs in
1148        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
1149        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
1150        separate and independent bugs (that affected different cases) have been
1151        fixed.
1153    39. Refactored the code to abolish the use of different opcodes for small
1154        capturing bracket numbers. This is a tidy that I avoided doing when I
1155        removed the limit on the number of capturing brackets for 3.5 back in 2001.
1156        The new approach is not only tidier, it makes it possible to reduce the
1157        memory needed to fix the previous bug (38).
1159    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
1160        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
1161        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
1162        mode.
1164    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
1165        report.
1167    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
1168        copy construction and assignment in the C++ wrapper.
1170    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
1171        couple of bugs that could have given wrong results in the "--newline=crlf"
1172        case.
1174    44. Added a number of casts and did some reorganization of signed/unsigned int
1175        variables following suggestions from Dair Grant. Also renamed the variable
1176        "this" as "item" because it is a C++ keyword.
1178    45. Arranged for dftables to add
1180          #include "pcre_internal.h"
1182        to pcre_chartables.c because without it, gcc 4.x may remove the array
1183        definition from the final binary if PCRE is built into a static library and
1184        dead code stripping is activated.
1186    46. For an unanchored pattern, if a match attempt fails at the start of a
1187        newline sequence, and the newline setting is CRLF or ANY, and the next two
1188        characters are CRLF, advance by two characters instead of one.
1191    Version 6.7 04-Jul-06
1192    ---------------------
1194     1. In order to handle tests when input lines are enormously long, pcretest has
1195        been re-factored so that it automatically extends its buffers when
1196        necessary. The code is crude, but this _is_ just a test program. The
1197        default size has been increased from 32K to 50K.
1199     2. The code in pcre_study() was using the value of the re argument before
1200        testing it for NULL. (Of course, in any sensible call of the function, it
1201        won't be NULL.)
1203     3. The memmove() emulation function in pcre_internal.h, which is used on
1204        systems that lack both memmove() and bcopy() - that is, hardly ever -
1205        was missing a "static" storage class specifier.
1207     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1208        containing an extended class (one that cannot be represented by a bitmap
1209        because it contains high-valued characters or Unicode property items, e.g.
1210        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1211        pattern, but PCRE should not loop if you do not (it no longer does).
1212        [Detail: two cases were found: (a) a repeated subpattern containing an
1213        extended class; (b) a recursive reference to a subpattern that followed a
1214        previous extended class. It wasn't skipping over the extended class
1215        correctly when UTF-8 mode was not set.]
1217     5. A negated single-character class was not being recognized as fixed-length
1218        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1219        compile error "lookbehind assertion is not fixed length".
1221     6. The RunPerlTest auxiliary script was showing an unexpected difference
1222        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1223        write a Perl script that can interpret lines of an input file either as
1224        byte characters or as UTF-8, which is what "perltest" was being required to
1225        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1226        can't do is switch easily at run time between having the "use utf8;" pragma
1227        or not. In the end, I fudged it by using the RunPerlTest script to insert
1228        "use utf8;" explicitly for the UTF-8 tests.
1230     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1231        the end of the subject string, contrary to the documentation and to what
1232        Perl does. This was true of both matching functions. Now it matches only at
1233        the start of the subject and immediately after *internal* newlines.
1235     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1236        a pointer to an int instead of a pointer to an unsigned long int. This
1237        caused problems on 64-bit systems.
1239     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1240        instance of the 'standard' template library not being so standard".
1242    10. There was no check on the number of named subpatterns nor the maximum
1243        length of a subpattern name. The product of these values is used to compute
1244        the size of the memory block for a compiled pattern. By supplying a very
1245        long subpattern name and a large number of named subpatterns, the size
1246        computation could be caused to overflow. This is now prevented by limiting
1247        the length of names to 32 characters, and the number of named subpatterns
1248        to 10,000.
1250    11. Subpatterns that are repeated with specific counts have to be replicated in
1251        the compiled pattern. The size of memory for this was computed from the
1252        length of the subpattern and the repeat count. The latter is limited to
1253        65535, but there was no limit on the former, meaning that integer overflow
1254        could in principle occur. The compiled length of a repeated subpattern is
1255        now limited to 30,000 bytes in order to prevent this.
1257    12. Added the optional facility to have named substrings with the same name.
1259    13. Added the ability to use a named substring as a condition, using the
1260        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1261        are numbers (not recommended). Forward references are permitted.
1263    14. Added forward references in named backreferences (if you see what I mean).
1265    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1266        pattern could run off the end of the subject. For example, the pattern
1267        "(?s)(.{1,5})"8 did this with the subject "ab".
1269    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1270        PCRE_CASELESS was set when matching characters that were quantified with ?
1271        or *.
1273    17. A character class other than a single negated character that had a minimum
1274        but no maximum quantifier - for example [ab]{6,} - was not handled
1275        correctly by pce_dfa_exec(). It would match only one character.
1277    18. A valid (though odd) pattern that looked like a POSIX character
1278        class but used an invalid character after [ (for example [[,abc,]]) caused
1279        pcre_compile() to give the error "Failed: internal error: code overflow" or
1280        in some cases to crash with a glibc free() error. This could even happen if
1281        the pattern terminated after [[ but there just happened to be a sequence of
1282        letters, a binary zero, and a closing ] in the memory that followed.
1284    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1285        over the years. Originally (before any Unicode support), just the bottom 8
1286        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1287        output from "man perlunicode" includes this:
1289          The regular expression compiler produces polymorphic opcodes.  That
1290          is, the pattern adapts to the data and automatically switches to
1291          the Unicode character scheme when presented with Unicode data--or
1292          instead uses a traditional byte scheme when presented with byte
1293          data.
1295        Sadly, a wide octal escape does not cause a switch, and in a string with
1296        no other multibyte characters, these octal escapes are treated as before.
1297        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1298        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1299        Unicode string.
1301        I have not perpetrated such confusion in PCRE. Up till now, it took just
1302        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1303        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1304        translate to the appropriate multibyte character.
1306    29. Applied some refactoring to reduce the number of warnings from Microsoft
1307        and Borland compilers. This has included removing the fudge introduced
1308        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1309        a warning about an unused variable.
1311    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1312        characters since release 4.0, because Perl (from release 5.004) does not.
1313        [Or at least, is documented not to: some releases seem to be in conflict
1314        with the documentation.] However, when a pattern was studied with
1315        pcre_study() and all its branches started with \s, PCRE still included VT
1316        as a possible starting character. Of course, this did no harm; it just
1317        caused an unnecessary match attempt.
1319    22. Removed a now-redundant internal flag bit that recorded the fact that case
1320        dependency changed within the pattern. This was once needed for "required
1321        byte" processing, but is no longer used. This recovers a now-scarce options
1322        bit. Also moved the least significant internal flag bit to the most-
1323        significant bit of the word, which was not previously used (hangover from
1324        the days when it was an int rather than a uint) to free up another bit for
1325        the future.
1327    23. Added support for CRLF line endings as well as CR and LF. As well as the
1328        default being selectable at build time, it can now be changed at runtime
1329        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1330        specify that it is scanning data with non-default line endings.
1332    24. Changed the definition of CXXLINK to make it agree with the definition of
1333        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1335    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1336        recursions. This makes a big different to stack usage for some patterns.
1338    26. If a subpattern containing a named recursion or subroutine reference such
1339        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1340        the space required for the compiled pattern went wrong and gave too small a
1341        value. Depending on the environment, this could lead to "Failed: internal
1342        error: code overflow at offset 49" or "glibc detected double free or
1343        corruption" errors.
1345    27. Applied patches from Google (a) to support the new newline modes and (b) to
1346        advance over multibyte UTF-8 characters in GlobalReplace.
1348    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1349        difference for some implementation of PCRE in some Windows version.
1351    29. Added some extra testing facilities to pcretest:
1353        \q<number>   in a data line sets the "match limit" value
1354        \Q<number>   in a data line sets the "match recursion limt" value
1355        -S <number>  sets the stack size, where <number> is in megabytes
1357        The -S option isn't available for Windows.
1360    Version 6.6 06-Feb-06
1361    ---------------------
1363     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1364        in pcreposix.h. I have copied the definition from pcre.h.
1366     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1367        because pcre.h is no longer a built file.
1369     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1370        not normally included in the compiled code.
1373  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
1374  ---------------------  ---------------------

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