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revision 17 by nigel, Sat Feb 24 21:38:29 2007 UTC revision 435 by ph10, Sat Sep 5 10:20:44 2009 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 8.00 ??-???-??
5    ----------------------
7    1.  The table for translating pcre_compile() error codes into POSIX error codes
8        was out-of-date, and there was no check on the pcre_compile() error code
9        being within the table. This could lead to an OK return being given in
10        error.
12    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
13        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
14        in a Windows environment.
16    3.  The pcregrep --count option prints the count for each file even when it is
17        zero, as does GNU grep. However, pcregrep was also printing all files when
18        --files-with-matches was added. Now, when both options are given, it prints
19        counts only for those files that have at least one match. (GNU grep just
20        prints the file name in this circumstance, but including the count seems
21        more useful - otherwise, why use --count?) Also ensured that the
22        combination -clh just lists non-zero counts, with no names.
24    4.  The long form of the pcregrep -F option was incorrectly implemented as
25        --fixed_strings instead of --fixed-strings. This is an incompatible change,
26        but it seems right to fix it, and I didn't think it was worth preserving
27        the old behaviour.
29    5.  The command line items --regex=pattern and --regexp=pattern were not
30        recognized by pcregrep, which required --regex pattern or --regexp pattern
31        (with a space rather than an '='). The man page documented the '=' forms,
32        which are compatible with GNU grep; these now work.
34    6.  No libpcreposix.pc file was created for pkg-config; there was just
35        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
37    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
38        when UCP support is not needed, by modifying the Python script that
39        generates it from Unicode data files. This should not matter if the module
40        is correctly used as a library, but I received one complaint about 50K of
41        unwanted data. My guess is that the person linked everything into his
42        program rather than using a library. Anyway, it does no harm.
44    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
45        was a minimum greater than 1 for a wide character in a possessive
46        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
47        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
48        character. Chaos in the form of incorrect output or a compiling loop could
49        result.
51    9.  The restrictions on what a pattern can contain when partial matching is
52        requested for pcre_exec() have been removed. All patterns can now be
53        partially matched by this function. In addition, if there are at least two
54        slots in the offset vector, the offset of the earliest inspected character
55        for the match and the offset of the end of the subject are set in them when
56        PCRE_ERROR_PARTIAL is returned.
58    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
59        synonymous with PCRE_PARTIAL, for backwards compatibility, and
60        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
61        and may be more useful for multi-segment matching, especially with
62        pcre_exec().
64    11. Partial matching with pcre_exec() is now more intuitive. A partial match
65        used to be given if ever the end of the subject was reached; now it is
66        given only if matching could not proceed because another character was
67        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
68        string "Z", which now yields "no match" instead of "partial match". In the
69        case of pcre_dfa_exec(), "no match" is given if every matching path for the
70        final character ended with (*FAIL).
72    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
73        if the pattern had a "must contain" character that was already found in the
74        earlier partial match, unless partial matching was again requested. For
75        example, with the pattern /dog.(body)?/, the "must contain" character is
76        "g". If the first part-match was for the string "dog", restarting with
77        "sbody" failed. This bug has been fixed.
79    13. The string returned by pcre_dfa_exec() after a partial match has been
80        changed so that it starts at the first inspected character rather than the
81        first character of the match. This makes a difference only if the pattern
82        starts with a lookbehind assertion or \b or \B (\K is not supported by
83        pcre_dfa_exec()). It's an incompatible change, but it makes the two
84        matching functions compatible, and I think it's the right thing to do.
86    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
87        so that the demonstration program is easily available in environments where
88        PCRE has not been installed from source.
90    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
91        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
92        library.
94    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
95        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
96        is not the first non-POSIX option to be added. Clearly some people find
97        these options useful.
99    17. If a caller to the POSIX matching function regexec() passes a non-zero
100        value for \fInmatch\fP with a NULL value for \fIpmatch\fP, the value of
101        \fInmatch\fP is forced to zero.
104    Version 7.9 11-Apr-09
105    ---------------------
107    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
108        (pcretest), all targets were linked against these libraries. This included
109        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
110        libraries. This caused unwanted dependencies to be created. This problem
111        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
112        pcretest is linked with readline.
114    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
115        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
116        moved outside it again, because FALSE and TRUE are already defined in AIX,
117        but BOOL is not.
119    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
120        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
122    4.  The pcregrep documentation said spaces were inserted as well as colons (or
123        hyphens) following file names and line numbers when outputting matching
124        lines. This is not true; no spaces are inserted. I have also clarified the
125        wording for the --colour (or --color) option.
127    5.  In pcregrep, when --colour was used with -o, the list of matching strings
128        was not coloured; this is different to GNU grep, so I have changed it to be
129        the same.
131    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
132        each matching line was coloured. Now it goes on to look for further matches
133        of any of the test patterns, which is the same behaviour as GNU grep.
135    7.  A pattern that could match an empty string could cause pcregrep to loop; it
136        doesn't make sense to accept an empty string match in pcregrep, so I have
137        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
138        seems to be how GNU grep behaves.
140    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
141        start or after a newline", because the conditional assertion was not being
142        correctly handled. The rule now is that both the assertion and what follows
143        in the first alternative must satisfy the test.
145    9.  If auto-callout was enabled in a pattern with a conditional group whose
146        condition was an assertion, PCRE could crash during matching, both with
147        pcre_exec() and pcre_dfa_exec().
149    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
150        used for matching.
152    11. Unicode property support in character classes was not working for
153        characters (bytes) greater than 127 when not in UTF-8 mode.
155    12. Added the -M command line option to pcretest.
157    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
159    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
161    16. Added comments and documentation about mis-use of no_arg in the C++
162        wrapper.
164    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
165        from Martin Jerabek that uses macro names for all relevant character and
166        string constants.
168    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
169        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
170        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
171        these, but not everybody uses configure.
173    19. A conditional group that had only one branch was not being correctly
174        recognized as an item that could match an empty string. This meant that an
175        enclosing group might also not be so recognized, causing infinite looping
176        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
177        with the subject "ab", where knowledge that the repeated group can match
178        nothing is needed in order to break the loop.
180    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
181        exec(), but without supplying a callout function, matching went wrong.
183    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
184        leak if the size of the offset vector was greater than 30. When the vector
185        is smaller, the saved offsets during recursion go onto a local stack
186        vector, but for larger vectors malloc() is used. It was failing to free
187        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
188        error, in fact).
190    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
191        heapframe that is used only when UTF-8 support is enabled. This caused no
192        problem, but was untidy.
194    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
195        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
196        included within another project.
198    24. Steven Van Ingelgem's patches to add more options to the CMake support,
199        slightly modified by me:
201          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
202              not building pcregrep.
204          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
205              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
207    25. Forward references, both numeric and by name, in patterns that made use of
208        duplicate group numbers, could behave incorrectly or give incorrect errors,
209        because when scanning forward to find the reference group, PCRE was not
210        taking into account the duplicate group numbers. A pattern such as
211        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
213    26. Changed a few more instances of "const unsigned char *" to USPTR, making
214        the feature of a custom pointer more persuasive (as requested by a user).
216    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
217        pcretest.c, inside #ifndefs, because it seems they are sometimes already
218        pre-defined.
220    28. Added support for (*UTF8) at the start of a pattern.
222    29. Arrange for flags added by the "release type" setting in CMake to be shown
223        in the configuration summary.
226    Version 7.8 05-Sep-08
227    ---------------------
229    1.  Replaced UCP searching code with optimized version as implemented for Ad
230        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
231        stage table and inline lookup instead of a function, giving speed ups of 2
232        to 5 times on some simple patterns that I tested. Permission was given to
233        distribute the MultiStage2.py script that generates the tables (it's not in
234        the tarball, but is in the Subversion repository).
236    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
237        scripts.
239    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
240        a group with a zero qualifier. The result of the study could be incorrect,
241        or the function might crash, depending on the pattern.
243    4.  Caseless matching was not working for non-ASCII characters in back
244        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
245        It now works when Unicode Property Support is available.
247    5.  In pcretest, an escape such as \x{de} in the data was always generating
248        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
249        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
250        truncation.
252    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
254    7.  Added two (int) casts to pcregrep when printing the difference of two
255        pointers, in case they are 64-bit values.
257    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
258        test 2 if it fails.
260    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
261        and a #define of that name to empty if it is not externally set. This is to
262        allow users of MSVC to set it if necessary.
264    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
265        the convenience functions in the pcre_get.c source file.
267    11. An option change at the start of a pattern that had top-level alternatives
268        could cause overwriting and/or a crash. This command provoked a crash in
269        some environments:
271          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
273        This potential security problem was recorded as CVE-2008-2371.
275    12. For a pattern where the match had to start at the beginning or immediately
276        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
277        pcre_dfa_exec() could read past the end of the passed subject if there was
278        no match. To help with detecting such bugs (e.g. with valgrind), I modified
279        pcretest so that it places the subject at the end of its malloc-ed buffer.
281    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
282        exec() might read past the end of the data buffer in UTF-8 mode.
284    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
285        the data contained the byte 0x85 as part of a UTF-8 character within its
286        first line. This applied both to normal and DFA matching.
288    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
289        /^[^d]*?$/8 failed to match "abc".
291    16. Added a missing copyright notice to pcrecpp_internal.h.
293    17. Make it more clear in the documentation that values returned from
294        pcre_exec() in ovector are byte offsets, not character counts.
296    18. Tidied a few places to stop certain compilers from issuing warnings.
298    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
299        supplied by Stefan Weber. I made a further small update for 7.8 because
300        there is a change of source arrangements: the pcre_searchfuncs.c module is
301        replaced by pcre_ucd.c.
304    Version 7.7 07-May-08
305    ---------------------
307    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
308        a string to a long long, pretend we don't even have a long long." This is
309        done by checking for the strtoq, strtoll, and _strtoi64 functions.
311    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
312        pre-7.6 versions, which defined a global no_arg variable instead of putting
313        it in the RE class. (See also #8 below.)
315    3.  Remove a line of dead code, identified by coverity and reported by Nuno
316        Lopes.
318    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
320        (1) The include/exclude patterns were being applied to the whole pathnames
321            of files, instead of just to the final components.
323        (2) If there was more than one level of directory, the subdirectories were
324            skipped unless they satisfied the include/exclude conditions. This is
325            inconsistent with GNU grep (and could even be seen as contrary to the
326            pcregrep specification - which I improved to make it absolutely clear).
327            The action now is always to scan all levels of directory, and just
328            apply the include/exclude patterns to regular files.
330    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
331        --exclude_dir in the tests to avoid scanning .svn directories.
333    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
334        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
335        doesn't support NULs in patterns.
337    7.  Added some missing "const"s to declarations of static tables in
338        pcre_compile.c and pcre_dfa_exec.c.
340    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
341        caused by fix #2  above. (Subsequently also a second patch to fix the
342        first patch. And a third patch - this was a messy problem.)
344    9.  Applied Craig's patch to remove the use of push_back().
346    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
347        matching function regexec().
349    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
350        which, however, unlike Perl's \g{...}, are subroutine calls, not back
351        references. PCRE supports relative numbers with this syntax (I don't think
352        Oniguruma does).
354    12. Previously, a group with a zero repeat such as (...){0} was completely
355        omitted from the compiled regex. However, this means that if the group
356        was called as a subroutine from elsewhere in the pattern, things went wrong
357        (an internal error was given). Such groups are now left in the compiled
358        pattern, with a new opcode that causes them to be skipped at execution
359        time.
361    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
362        to the way PCRE behaves:
364        (a) A lone ] character is dis-allowed (Perl treats it as data).
366        (b) A back reference to an unmatched subpattern matches an empty string
367            (Perl fails the current match path).
369        (c) A data ] in a character class must be notated as \] because if the
370            first data character in a class is ], it defines an empty class. (In
371            Perl it is not possible to have an empty class.) The empty class []
372            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
373            The negative empty class [^] matches any one character, independently
374            of the DOTALL setting.
376    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
377        non-existent subpattern following a character class starting with ']' and
378        containing () gave an internal compiling error instead of "reference to
379        non-existent subpattern". Fortunately, when the pattern did exist, the
380        compiled code was correct. (When scanning forwards to check for the
381        existencd of the subpattern, it was treating the data ']' as terminating
382        the class, so got the count wrong. When actually compiling, the reference
383        was subsequently set up correctly.)
385    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
386        it was being rejected as not supported by pcre_dfa_exec(), even though
387        other assertions are supported. I have made pcre_dfa_exec() support
388        (*FAIL).
390    16. The implementation of 13c above involved the invention of a new opcode,
391        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
392        cannot be changed at match time, I realized I could make a small
393        improvement to matching performance by compiling OP_ALLANY instead of
394        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
395        on the OP_ANY path.
397    17. Compiling pcretest on Windows with readline support failed without the
398        following two fixes: (1) Make the unistd.h include conditional on
399        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
401    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
402        ncurses library to be included for pcretest when ReadLine support is
403        requested, but also to allow for it to be overridden. This patch came from
404        Daniel Bergström.
406    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
407        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
408        any errors with the current Unicode tables. Thanks to Peter Kankowski for
409        spotting this.
412    Version 7.6 28-Jan-08
413    ---------------------
415    1.  A character class containing a very large number of characters with
416        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
417        overflow.
419    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
420        HAVE_LONG_LONG is not defined.
422    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
423        bring them up to date and include new features. This patch includes:
425        - Fixed PH's badly added libz and libbz2 support.
426        - Fixed a problem with static linking.
427        - Added pcredemo. [But later removed - see 7 below.]
428        - Fixed dftables problem and added an option.
429        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
430            HAVE_LONG_LONG.
431        - Added readline support for pcretest.
432        - Added an listing of the option settings after cmake has run.
434    4.  A user submitted a patch to Makefile that makes it easy to create
435        "pcre.dll" under mingw when using Configure/Make. I added stuff to
436        Makefile.am that cause it to include this special target, without
437        affecting anything else. Note that the same mingw target plus all
438        the other distribution libraries and programs are now supported
439        when configuring with CMake (see 6 below) instead of with
440        Configure/Make.
442    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
443        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
444        exported in the Windows port". It has not yet been confirmed that the patch
445        solves the problem, but it does no harm.
447    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
448        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
449        with CMake, and also correct the comment about stack recursion.
451    7.  Remove the automatic building of pcredemo from the ./configure system and
452        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
453        of a program that users should build themselves after PCRE is installed, so
454        building it automatically is not really right. What is more, it gave
455        trouble in some build environments.
457    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
460    Version 7.5 10-Jan-08
461    ---------------------
463    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
464        values in parens when parsing an RE using the C++ wrapper."
466    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
467        Characters greater than 255 were excluded from the class instead of being
468        included.
470    3.  The same bug as (2) above applied to negated POSIX classes such as
471        [:^space:].
473    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
474        defined or documented. It seems to have been a typo for PCRE_STATIC, so
475        I have changed it.
477    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
478        first named subpattern) and a construct such as (?&a) would reference the
479        first named subpattern whose name started with "a" (in other words, the
480        length check was missing). Both these problems are fixed. "Subpattern name
481        expected" is now given for (?&) (a zero-length name), and this patch also
482        makes it give the same error for \k'' (previously it complained that that
483        was a reference to a non-existent subpattern).
485    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
486        this is right because (?- can be followed by option settings as well as by
487        digits. I have, however, made the messages clearer.
489    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
490        than the number used in the conditional) now cause a compile-time error.
491        This is actually not compatible with Perl, which accepts such patterns, but
492        treats the conditional as always being FALSE (as PCRE used to), but it
493        seems to me that giving a diagnostic is better.
495    8.  Change "alphameric" to the more common word "alphanumeric" in comments
496        and messages.
498    9.  Fix two occurrences of "backslash" in comments that should have been
499        "backspace".
501    10. Remove two redundant lines of code that can never be obeyed (their function
502        was moved elsewhere).
504    11. The program that makes PCRE's Unicode character property table had a bug
505        which caused it to generate incorrect table entries for sequences of
506        characters that have the same character type, but are in different scripts.
507        It amalgamated them into a single range, with the script of the first of
508        them. In other words, some characters were in the wrong script. There were
509        thirteen such cases, affecting characters in the following ranges:
511          U+002b0 - U+002c1
512          U+0060c - U+0060d
513          U+0061e - U+00612
514          U+0064b - U+0065e
515          U+0074d - U+0076d
516          U+01800 - U+01805
517          U+01d00 - U+01d77
518          U+01d9b - U+01dbf
519          U+0200b - U+0200f
520          U+030fc - U+030fe
521          U+03260 - U+0327f
522          U+0fb46 - U+0fbb1
523          U+10450 - U+1049d
525    12. The -o option (show only the matching part of a line) for pcregrep was not
526        compatible with GNU grep in that, if there was more than one match in a
527        line, it showed only the first of them. It now behaves in the same way as
528        GNU grep.
530    13. If the -o and -v options were combined for pcregrep, it printed a blank
531        line for every non-matching line. GNU grep prints nothing, and pcregrep now
532        does the same. The return code can be used to tell if there were any
533        non-matching lines.
535    14. Added --file-offsets and --line-offsets to pcregrep.
537    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
538        infinitely looping recursion. The bug was that positive lookaheads were not
539        being skipped when checking for a possible empty match (negative lookaheads
540        and both kinds of lookbehind were skipped).
542    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
543        inclusion of <windows.h> to before rather than after the definition of
544        INVALID_FILE_ATTRIBUTES (patch from David Byron).
546    17. Specifying a possessive quantifier with a specific limit for a Unicode
547        character property caused pcre_compile() to compile bad code, which led at
548        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
549        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
550        caused the error; without that there was no problem.
552    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
554    19. Added --enable-pcretest-libreadline.
556    20. In pcrecpp.cc, the variable 'count' was incremented twice in
557        RE::GlobalReplace(). As a result, the number of replacements returned was
558        double what it should be. I removed one of the increments, but Craig sent a
559        later patch that removed the other one (the right fix) and added unit tests
560        that check the return values (which was not done before).
562    21. Several CMake things:
564        (1) Arranged that, when cmake is used on Unix, the libraries end up with
565            the names libpcre and libpcreposix, not just pcre and pcreposix.
567        (2) The above change means that pcretest and pcregrep are now correctly
568            linked with the newly-built libraries, not previously installed ones.
572    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
573        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
574        UTF-8 newline character). The key issue is that the pattern starts .*;
575        this means that the match must be either at the beginning, or after a
576        newline. The bug was in the code for advancing after a failed match and
577        checking that the new position followed a newline. It was not taking
578        account of UTF-8 characters correctly.
580    23. PCRE was behaving differently from Perl in the way it recognized POSIX
581        character classes. PCRE was not treating the sequence [:...:] as a
582        character class unless the ... were all letters. Perl, however, seems to
583        allow any characters between [: and :], though of course it rejects as
584        unknown any "names" that contain non-letters, because all the known class
585        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
586        for example, whereas PCRE did not - it did not recognize a POSIX character
587        class. This seemed a bit dangerous, so the code has been changed to be
588        closer to Perl. The behaviour is not identical to Perl, because PCRE will
589        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
590        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
591        Perl does, and where it didn't before.
593    24. Rewrite so as to remove the single use of %n from pcregrep because in some
594        Windows environments %n is disabled by default.
597    Version 7.4 21-Sep-07
598    ---------------------
600    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
601        means that a class such as [\s] counted as "explicit reference to CR or
602        LF". That isn't really right - the whole point of the change was to try to
603        help when there was an actual mention of one of the two characters. So now
604        the change happens only if \r or \n (or a literal CR or LF) character is
605        encountered.
607    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
608        of both had grown to the point where there were only 3 bits left.
609        Fortunately, there was spare space in the data structure, and so I have
610        moved the internal flags into a new 16-bit field to free up more option
611        bits.
613    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
614        but did not set the internal JCHANGED flag - either of these is enough to
615        control the way the "get" function works - but the PCRE_INFO_JCHANGED
616        facility is supposed to tell if (?J) was ever used, so now (?J) at the
617        start sets both bits.
619    4.  Added options (at build time, compile time, exec time) to change \R from
620        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
622    5.  doc/pcresyntax.html was missing from the distribution.
624    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
625        compatibility, even though it is no longer used.
627    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
628        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
629        windows.h file is present (where different names are used). [This was
630        reversed later after testing - see 16 below.]
632    8.  Changed all #include <config.h> to #include "config.h". There were also
633        some further <pcre.h> cases that I changed to "pcre.h".
635    9.  When pcregrep was used with the --colour option, it missed the line ending
636        sequence off the lines that it output.
638    10. It was pointed out to me that arrays of string pointers cause lots of
639        relocations when a shared library is dynamically loaded. A technique of
640        using a single long string with a table of offsets can drastically reduce
641        these. I have refactored PCRE in four places to do this. The result is
642        dramatic:
644          Originally:                          290
645          After changing UCP table:            187
646          After changing error message table:   43
647          After changing table of "verbs"       36
648          After changing table of Posix names   22
650        Thanks to the folks working on Gregex for glib for this insight.
652    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
653        unicode-properties was also set.
655    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
657    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
658        checked only for CRLF.
660    14. Added casts to pcretest.c to avoid compiler warnings.
662    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
664    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
665        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
666        entirely. This removes changes made in 7 above.
668    17. The CMake files have been updated, and there is now more information about
669        building with CMake in the NON-UNIX-USE document.
672    Version 7.3 28-Aug-07
673    ---------------------
675     1. In the rejigging of the build system that eventually resulted in 7.1, the
676        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
677        brackets there is not right, since it causes compilers to look for an
678        installed pcre.h, not the version that is in the source that is being
679        compiled (which of course may be different). I have changed it back to:
681          #include "pcre.h"
683        I have a vague recollection that the change was concerned with compiling in
684        different directories, but in the new build system, that is taken care of
685        by the VPATH setting the Makefile.
687     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
688        when the subject happened to end in the byte 0x85 (e.g. if the last
689        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
690        characters but of course it shouldn't be taken as a newline when it is part
691        of another character. The bug was that, for an unlimited repeat of . in
692        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
693        characters when looking for a newline.
695     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
697     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
698        in debug output.
700     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
701        long printing in the pcrecpp unittest when running under MinGW.
703     6. ESC_K was left out of the EBCDIC table.
705     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
706        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
707        limit also applies to "virtual nesting" when a pattern is recursive, and in
708        this case 1000 isn't so big. I have been able to remove this limit at the
709        expense of backing off one optimization in certain circumstances. Normally,
710        when pcre_exec() would call its internal match() function recursively and
711        immediately return the result unconditionally, it uses a "tail recursion"
712        feature to save stack. However, when a subpattern that can match an empty
713        string has an unlimited repetition quantifier, it no longer makes this
714        optimization. That gives it a stack frame in which to save the data for
715        checking that an empty string has been matched. Previously this was taken
716        from the 1000-entry workspace that had been reserved. So now there is no
717        explicit limit, but more stack is used.
719     8. Applied Daniel's patches to solve problems with the import/export magic
720        syntax that is required for Windows, and which was going wrong for the
721        pcreposix and pcrecpp parts of the library. These were overlooked when this
722        problem was solved for the main library.
724     9. There were some crude static tests to avoid integer overflow when computing
725        the size of patterns that contain repeated groups with explicit upper
726        limits. As the maximum quantifier is 65535, the maximum group length was
727        set at 30,000 so that the product of these two numbers did not overflow a
728        32-bit integer. However, it turns out that people want to use groups that
729        are longer than 30,000 bytes (though not repeat them that many times).
730        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
731        made it possible to implement the integer overflow checks in a much more
732        dynamic way, which I have now done. The artificial limitation on group
733        length has been removed - we now have only the limit on the total length of
734        the compiled pattern, which depends on the LINK_SIZE setting.
736    10. Fixed a bug in the documentation for get/copy named substring when
737        duplicate names are permitted. If none of the named substrings are set, the
738        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
739        empty string.
741    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
742        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
743        because the ] is interpreted as the first data character and the
744        terminating ] is not found. PCRE has been made compatible with Perl in this
745        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
746        cause memory overwriting.
748    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
749        string has been matched (to stop an infinite loop). It was not recognizing
750        a conditional subpattern that could match an empty string if that
751        subpattern was within another subpattern. For example, it looped when
752        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
753        condition was not nested. This bug has been fixed.
755    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
756        past the start of the subject in the presence of bytes with the top bit
757        set, for example "\x8aBCD".
759    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
760        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
762    14. Optimized (?!) to (*FAIL).
764    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
765        This restricts code points to be within the range 0 to 0x10FFFF, excluding
766        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
767        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
768        does: it's just the validity check that is more restrictive.
770    16. Inserted checks for integer overflows during escape sequence (backslash)
771        processing, and also fixed erroneous offset values for syntax errors during
772        backslash processing.
774    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
775        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
777    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
778        caused an overrun.
780    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
781        something other than just ASCII characters) inside a group that had an
782        unlimited repeat caused a loop at compile time (while checking to see
783        whether the group could match an empty string).
785    20. Debugging a pattern containing \p or \P could cause a crash. For example,
786        [\P{Any}] did so. (Error in the code for printing property names.)
788    21. An orphan \E inside a character class could cause a crash.
790    22. A repeated capturing bracket such as (A)? could cause a wild memory
791        reference during compilation.
793    23. There are several functions in pcre_compile() that scan along a compiled
794        expression for various reasons (e.g. to see if it's fixed length for look
795        behind). There were bugs in these functions when a repeated \p or \P was
796        present in the pattern. These operators have additional parameters compared
797        with \d, etc, and these were not being taken into account when moving along
798        the compiled data. Specifically:
800        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
801            length.
803        (b) An item such as \pL+ within a repeated group could cause crashes or
804            loops.
806        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
807            "reference to non-existent subpattern" error.
809        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
811    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
812        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
814    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
816    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
817        character were causing crashes (broken optimization).
819    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
820        \p or \P) caused a compile-time loop.
822    28. More problems have arisen in unanchored patterns when CRLF is a valid line
823        break. For example, the unstudied pattern [\r\n]A does not match the string
824        "\r\nA" because change 7.0/46 below moves the current point on by two
825        characters after failing to match at the start. However, the pattern \nA
826        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
827        the same is true. There doesn't seem any very clean way out of this, but
828        what I have chosen to do makes the common cases work: PCRE now takes note
829        of whether there can be an explicit match for \r or \n anywhere in the
830        pattern, and if so, 7.0/46 no longer applies. As part of this change,
831        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
832        pattern has explicit CR or LF references.
834    29. Added (*CR) etc for changing newline setting at start of pattern.
837    Version 7.2 19-Jun-07
838    ---------------------
840     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
841        which is apparently normally available under Windows.
843     2. Re-jig the pcregrep tests with different newline settings in an attempt
844        to make them independent of the local environment's newline setting.
846     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
848     4. Some of the "internals" tests were previously cut out when the link size
849        was not 2, because the output contained actual offsets. The recent new
850        "Z" feature of pcretest means that these can be cut out, making the tests
851        usable with all link sizes.
853     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
854        stack recursion. This gives a massive performance boost under BSD, but just
855        a small improvement under Linux. However, it saves one field in the frame
856        in all cases.
858     6. Added more features from the forthcoming Perl 5.10:
860        (a) (?-n) (where n is a string of digits) is a relative subroutine or
861            recursion call. It refers to the nth most recently opened parentheses.
863        (b) (?+n) is also a relative subroutine call; it refers to the nth next
864            to be opened parentheses.
866        (c) Conditions that refer to capturing parentheses can be specified
867            relatively, for example, (?(-2)... or (?(+3)...
869        (d) \K resets the start of the current match so that everything before
870            is not part of it.
872        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
874        (f) \g{name} is another synonym - part of Perl 5.10's unification of
875            reference syntax.
877        (g) (?| introduces a group in which the numbering of parentheses in each
878            alternative starts with the same number.
880        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
882     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
885     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
886        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
887        for detecting groups that can match an empty string.
889     9. A pattern with a very large number of alternatives (more than several
890        hundred) was running out of internal workspace during the pre-compile
891        phase, where pcre_compile() figures out how much memory will be needed. A
892        bit of new cunning has reduced the workspace needed for groups with
893        alternatives. The 1000-alternative test pattern now uses 12 bytes of
894        workspace instead of running out of the 4096 that are available.
896    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
898    11. Applied patch from Google to remove an optimization that didn't quite work.
899        The report of the bug said:
901          pcrecpp::RE("a*").FullMatch("aaa") matches, while
902          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
903          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
905    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
906        it matched the wrong number of bytes.
909    Version 7.1 24-Apr-07
910    ---------------------
912     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
913        that is more "standard", making use of automake and other Autotools. There
914        is some re-arrangement of the files and adjustment of comments consequent
915        on this.
917     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
918        for recursive directory scanning broke on some systems because the files
919        are not scanned in any specific order and on different systems the order
920        was different. A call to "sort" has been inserted into RunGrepTest for the
921        approprate test as a short-term fix. In the longer term there may be an
922        alternative.
924     3. I had an email from Eric Raymond about problems translating some of PCRE's
925        man pages to HTML (despite the fact that I distribute HTML pages, some
926        people do their own conversions for various reasons). The problems
927        concerned the use of low-level troff macros .br and .in. I have therefore
928        removed all such uses from the man pages (some were redundant, some could
929        be replaced by .nf/.fi pairs). The 132html script that I use to generate
930        HTML has been updated to handle .nf/.fi and to complain if it encounters
931        .br or .in.
933     4. Updated comments in configure.ac that get placed in config.h.in and also
934        arranged for config.h to be included in the distribution, with the name
935        config.h.generic, for the benefit of those who have to compile without
936        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
938     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
939        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
940        makevp.bat for the current PCRE, using the additional files
941        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
943     6. A Windows user reported a minor discrepancy with test 2, which turned out
944        to be caused by a trailing space on an input line that had got lost in his
945        copy. The trailing space was an accident, so I've just removed it.
947     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
948        that is needed.
950     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
951        as "const" (a) because they are and (b) because it helps the PHP
952        maintainers who have recently made a script to detect big data structures
953        in the php code that should be moved to the .rodata section. I remembered
954        to update Builducptable as well, so it won't revert if ucptable.h is ever
955        re-created.
957     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
958        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
959        order to be able to cut out the UTF-8 tables in the latter when UTF-8
960        support is not required. This saves 1.5-2K of code, which is important in
961        some applications.
963        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
964        so as not to refer to the tables, even though these functions will never be
965        called when UTF-8 support is disabled. Otherwise there are problems with a
966        shared library.
968    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
970        (a) It was defining its arguments as char * instead of void *.
972        (b) It was assuming that all moves were upwards in memory; this was true
973            a long time ago when I wrote it, but is no longer the case.
975        The emulated memove() is provided for those environments that have neither
976        memmove() nor bcopy(). I didn't think anyone used it these days, but that
977        is clearly not the case, as these two bugs were recently reported.
979    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
980        and Detrail to create the HTML documentation, the .txt form of the man
981        pages, and it removes trailing spaces from listed files. It also creates
982        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
983        case, it wraps all the #defines with #ifndefs. This script should be run
984        before "make dist".
986    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
987        with Unicode property support.
989        (a) For a maximizing quantifier, if the two different cases of the
990            character were of different lengths in their UTF-8 codings (there are
991            some cases like this - I found 11), and the matching function had to
992            back up over a mixture of the two cases, it incorrectly assumed they
993            were both the same length.
995        (b) When PCRE was configured to use the heap rather than the stack for
996            recursion during matching, it was not correctly preserving the data for
997            the other case of a UTF-8 character when checking ahead for a match
998            while processing a minimizing repeat. If the check also involved
999            matching a wide character, but failed, corruption could cause an
1000            erroneous result when trying to check for a repeat of the original
1001            character.
1003    13. Some tidying changes to the testing mechanism:
1005        (a) The RunTest script now detects the internal link size and whether there
1006            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
1007            values substituted by "configure". (The RunGrepTest script already did
1008            this for UTF-8.) The configure.ac script no longer substitutes the
1009            relevant variables.
1011        (b) The debugging options /B and /D in pcretest show the compiled bytecode
1012            with length and offset values. This means that the output is different
1013            for different internal link sizes. Test 2 is skipped for link sizes
1014            other than 2 because of this, bypassing the problem. Unfortunately,
1015            there was also a test in test 3 (the locale tests) that used /B and
1016            failed for link sizes other than 2. Rather than cut the whole test out,
1017            I have added a new /Z option to pcretest that replaces the length and
1018            offset values with spaces. This is now used to make test 3 independent
1019            of link size. (Test 2 will be tidied up later.)
1021    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
1022        segmentation fault instead of returning the appropriate error message.
1024    15. In multiline mode when the newline sequence was set to "any", the pattern
1025        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
1026        This doesn't seem right; it now treats the CRLF combination as the line
1027        ending, and so does not match in that case. It's only a pattern such as ^$
1028        that would hit this one: something like ^ABC$ would have failed after \r
1029        and then tried again after \r\n.
1031    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
1032        in an attempt to make files that differ only in their line terminators
1033        compare equal. This works on Linux.
1035    17. Under certain error circumstances pcregrep might try to free random memory
1036        as it exited. This is now fixed, thanks to valgrind.
1038    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
1039        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
1040        was because its rules for how to advance for /g after matching an empty
1041        string at the end of a line did not allow for this case. They now check for
1042        it specially.
1044    20. pcretest is supposed to handle patterns and data of any length, by
1045        extending its buffers when necessary. It was getting this wrong when the
1046        buffer for a data line had to be extended.
1048    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
1049        CRLF as a newline sequence.
1051    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
1052        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
1053        I have nevertheless tidied it up.
1055    23. Added some casts to kill warnings from HP-UX ia64 compiler.
1057    24. Added a man page for pcre-config.
1060    Version 7.0 19-Dec-06
1061    ---------------------
1063     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
1064        moving to gcc 4.1.1.
1066     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
1067        sys/time.h, which is documented as needed for this function. It doesn't
1068        seem to matter on Linux, but it showed up on some releases of OS X.
1070     3. It seems that there are systems where bytes whose values are greater than
1071        127 match isprint() in the "C" locale. The "C" locale should be the
1072        default when a C program starts up. In most systems, only ASCII printing
1073        characters match isprint(). This difference caused the output from pcretest
1074        to vary, making some of the tests fail. I have changed pcretest so that:
1076        (a) When it is outputting text in the compiled version of a pattern, bytes
1077            other than 32-126 are always shown as hex escapes.
1079        (b) When it is outputting text that is a matched part of a subject string,
1080            it does the same, unless a different locale has been set for the match
1081            (using the /L modifier). In this case, it uses isprint() to decide.
1083     4. Fixed a major bug that caused incorrect computation of the amount of memory
1084        required for a compiled pattern when options that changed within the
1085        pattern affected the logic of the preliminary scan that determines the
1086        length. The relevant options are -x, and -i in UTF-8 mode. The result was
1087        that the computed length was too small. The symptoms of this bug were
1088        either the PCRE error "internal error: code overflow" from pcre_compile(),
1089        or a glibc crash with a message such as "pcretest: free(): invalid next
1090        size (fast)". Examples of patterns that provoked this bug (shown in
1091        pcretest format) are:
1093          /(?-x: )/x
1094          /(?x)(?-x: \s*#\s*)/
1095          /((?i)[\x{c0}])/8
1096          /(?i:[\x{c0}])/8
1098        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
1099        is now done differently.
1101     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
1102        wrapper classes; (b) implement a new function in the C++ scanner that is
1103        more efficient than the old way of doing things because it avoids levels of
1104        recursion in the regex matching; (c) add a paragraph to the documentation
1105        for the FullMatch() function.
1107     6. The escape sequence \n was being treated as whatever was defined as
1108        "newline". Not only was this contrary to the documentation, which states
1109        that \n is character 10 (hex 0A), but it also went horribly wrong when
1110        "newline" was defined as CRLF. This has been fixed.
1112     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
1113        was being set to -1 for the "end of line" case (supposedly a value that no
1114        character can have). Though this value is never used (the check for end of
1115        line is "zero bytes in current character"), it caused compiler complaints.
1116        I've changed it to 0xffffffff.
1118     8. In pcre_version.c, the version string was being built by a sequence of
1119        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
1120        string (as it is for production releases) called a macro with an empty
1121        argument. The C standard says the result of this is undefined. The gcc
1122        compiler treats it as an empty string (which was what was wanted) but it is
1123        reported that Visual C gives an error. The source has been hacked around to
1124        avoid this problem.
1126     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
1127        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
1128        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
1129        of them did).
1131    10. Originally, pcretest opened its input and output without "b"; then I was
1132        told that "b" was needed in some environments, so it was added for release
1133        5.0 to both the input and output. (It makes no difference on Unix-like
1134        systems.) Later I was told that it is wrong for the input on Windows. I've
1135        now abstracted the modes into two macros, to make it easier to fiddle with
1136        them, and removed "b" from the input mode under Windows.
1138    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
1140    12. Added -help and --help to pcretest as an official way of being reminded
1141        of the options.
1143    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
1144        and pcrecpp.cc because they annoy compilers at high warning levels.
1146    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
1148    15. Fixed an occurrence of == in configure.ac that should have been = (shell
1149        scripts are not C programs :-) and which was not noticed because it works
1150        on Linux.
1152    16. pcretest is supposed to handle any length of pattern and data line (as one
1153        line or as a continued sequence of lines) by extending its input buffer if
1154        necessary. This feature was broken for very long pattern lines, leading to
1155        a string of junk being passed to pcre_compile() if the pattern was longer
1156        than about 50K.
1158    17. I have done a major re-factoring of the way pcre_compile() computes the
1159        amount of memory needed for a compiled pattern. Previously, there was code
1160        that made a preliminary scan of the pattern in order to do this. That was
1161        OK when PCRE was new, but as the facilities have expanded, it has become
1162        harder and harder to keep it in step with the real compile phase, and there
1163        have been a number of bugs (see for example, 4 above). I have now found a
1164        cunning way of running the real compile function in a "fake" mode that
1165        enables it to compute how much memory it would need, while actually only
1166        ever using a few hundred bytes of working memory and without too many
1167        tests of the mode. This should make future maintenance and development
1168        easier. A side effect of this work is that the limit of 200 on the nesting
1169        depth of parentheses has been removed (though this was never a serious
1170        limitation, I suspect). However, there is a downside: pcre_compile() now
1171        runs more slowly than before (30% or more, depending on the pattern). I
1172        hope this isn't a big issue. There is no effect on runtime performance.
1174    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
1175        newline (only possible for the last line of a file) and it was a
1176        pattern that set a locale (followed by /Lsomething), pcretest crashed.
1178    19. Added additional timing features to pcretest. (1) The -tm option now times
1179        matching only, not compiling. (2) Both -t and -tm can be followed, as a
1180        separate command line item, by a number that specifies the number of
1181        repeats to use when timing. The default is 50000; this gives better
1182        precision, but takes uncomfortably long for very large patterns.
1184    20. Extended pcre_study() to be more clever in cases where a branch of a
1185        subpattern has no definite first character. For example, (a*|b*)[cd] would
1186        previously give no result from pcre_study(). Now it recognizes that the
1187        first character must be a, b, c, or d.
1189    21. There was an incorrect error "recursive call could loop indefinitely" if
1190        a subpattern (or the entire pattern) that was being tested for matching an
1191        empty string contained only one non-empty item after a nested subpattern.
1192        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
1193        incorrectly, because the \d was being skipped in the check.
1195    22. The pcretest program now has a new pattern option /B and a command line
1196        option -b, which is equivalent to adding /B to every pattern. This causes
1197        it to show the compiled bytecode, without the additional information that
1198        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
1199        is the same as /B/I).
1201    23. A new optimization is now able automatically to treat some sequences such
1202        as a*b as a*+b. More specifically, if something simple (such as a character
1203        or a simple class like \d) has an unlimited quantifier, and is followed by
1204        something that cannot possibly match the quantified thing, the quantifier
1205        is automatically "possessified".
1207    24. A recursive reference to a subpattern whose number was greater than 39
1208        went wrong under certain circumstances in UTF-8 mode. This bug could also
1209        have affected the operation of pcre_study().
1211    25. Realized that a little bit of performance could be had by replacing
1212        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
1214    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
1216    27. Possessive quantifiers such as a++ were previously implemented by turning
1217        them into atomic groups such as ($>a+). Now they have their own opcodes,
1218        which improves performance. This includes the automatically created ones
1219        from 23 above.
1221    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
1222        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
1223        the first matched character to be a colon. This applied both to named and
1224        numbered groups.
1226    29. The ucpinternal.h header file was missing its idempotency #ifdef.
1228    30. I was sent a "project" file called libpcre.a.dev which I understand makes
1229        building PCRE on Windows easier, so I have included it in the distribution.
1231    31. There is now a check in pcretest against a ridiculously large number being
1232        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
1233        loop, the loop is abandoned.
1235    32. Forward references to subpatterns in conditions such as (?(2)...) where
1236        subpattern 2 is defined later cause pcre_compile() to search forwards in
1237        the pattern for the relevant set of parentheses. This search went wrong
1238        when there were unescaped parentheses in a character class, parentheses
1239        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
1241    33. "Subroutine" calls and backreferences were previously restricted to
1242        referencing subpatterns earlier in the regex. This restriction has now
1243        been removed.
1245    34. Added a number of extra features that are going to be in Perl 5.10. On the
1246        whole, these are just syntactic alternatives for features that PCRE had
1247        previously implemented using the Python syntax or my own invention. The
1248        other formats are all retained for compatibility.
1250        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
1251            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
1252            also .NET compatible.
1254        (b) A recursion or subroutine call to a named group can now be defined as
1255            (?&name) as well as (?P>name).
1257        (c) A backreference to a named group can now be defined as \k<name> or
1258            \k'name' as well as (?P=name). The new forms, as well as being in Perl
1259            5.10, are also .NET compatible.
1261        (d) A conditional reference to a named group can now use the syntax
1262            (?(<name>) or (?('name') as well as (?(name).
1264        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
1265            groups (named and numbered) that are never evaluated inline, but can be
1266            called as "subroutines" from elsewhere. In effect, the DEFINE condition
1267            is always false. There may be only one alternative in such a group.
1269        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
1270            as the simple (?(R). The condition is true only if the most recent
1271            recursion is that of the given number or name. It does not search out
1272            through the entire recursion stack.
1274        (g) The escape \gN or \g{N} has been added, where N is a positive or
1275            negative number, specifying an absolute or relative reference.
1277    35. Tidied to get rid of some further signed/unsigned compiler warnings and
1278        some "unreachable code" warnings.
1280    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
1281        things, this adds five new scripts.
1283    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
1284        There were also incompatibilities regarding the handling of \Q..\E inside
1285        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
1286        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
1288    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
1289        matches an empty string, and forcibly breaks the loop. There were bugs in
1290        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
1291        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
1292        separate and independent bugs (that affected different cases) have been
1293        fixed.
1295    39. Refactored the code to abolish the use of different opcodes for small
1296        capturing bracket numbers. This is a tidy that I avoided doing when I
1297        removed the limit on the number of capturing brackets for 3.5 back in 2001.
1298        The new approach is not only tidier, it makes it possible to reduce the
1299        memory needed to fix the previous bug (38).
1301    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
1302        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
1303        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
1304        mode.
1306    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
1307        report.
1309    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
1310        copy construction and assignment in the C++ wrapper.
1312    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
1313        couple of bugs that could have given wrong results in the "--newline=crlf"
1314        case.
1316    44. Added a number of casts and did some reorganization of signed/unsigned int
1317        variables following suggestions from Dair Grant. Also renamed the variable
1318        "this" as "item" because it is a C++ keyword.
1320    45. Arranged for dftables to add
1322          #include "pcre_internal.h"
1324        to pcre_chartables.c because without it, gcc 4.x may remove the array
1325        definition from the final binary if PCRE is built into a static library and
1326        dead code stripping is activated.
1328    46. For an unanchored pattern, if a match attempt fails at the start of a
1329        newline sequence, and the newline setting is CRLF or ANY, and the next two
1330        characters are CRLF, advance by two characters instead of one.
1333    Version 6.7 04-Jul-06
1334    ---------------------
1336     1. In order to handle tests when input lines are enormously long, pcretest has
1337        been re-factored so that it automatically extends its buffers when
1338        necessary. The code is crude, but this _is_ just a test program. The
1339        default size has been increased from 32K to 50K.
1341     2. The code in pcre_study() was using the value of the re argument before
1342        testing it for NULL. (Of course, in any sensible call of the function, it
1343        won't be NULL.)
1345     3. The memmove() emulation function in pcre_internal.h, which is used on
1346        systems that lack both memmove() and bcopy() - that is, hardly ever -
1347        was missing a "static" storage class specifier.
1349     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1350        containing an extended class (one that cannot be represented by a bitmap
1351        because it contains high-valued characters or Unicode property items, e.g.
1352        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1353        pattern, but PCRE should not loop if you do not (it no longer does).
1354        [Detail: two cases were found: (a) a repeated subpattern containing an
1355        extended class; (b) a recursive reference to a subpattern that followed a
1356        previous extended class. It wasn't skipping over the extended class
1357        correctly when UTF-8 mode was not set.]
1359     5. A negated single-character class was not being recognized as fixed-length
1360        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1361        compile error "lookbehind assertion is not fixed length".
1363     6. The RunPerlTest auxiliary script was showing an unexpected difference
1364        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1365        write a Perl script that can interpret lines of an input file either as
1366        byte characters or as UTF-8, which is what "perltest" was being required to
1367        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1368        can't do is switch easily at run time between having the "use utf8;" pragma
1369        or not. In the end, I fudged it by using the RunPerlTest script to insert
1370        "use utf8;" explicitly for the UTF-8 tests.
1372     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1373        the end of the subject string, contrary to the documentation and to what
1374        Perl does. This was true of both matching functions. Now it matches only at
1375        the start of the subject and immediately after *internal* newlines.
1377     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1378        a pointer to an int instead of a pointer to an unsigned long int. This
1379        caused problems on 64-bit systems.
1381     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1382        instance of the 'standard' template library not being so standard".
1384    10. There was no check on the number of named subpatterns nor the maximum
1385        length of a subpattern name. The product of these values is used to compute
1386        the size of the memory block for a compiled pattern. By supplying a very
1387        long subpattern name and a large number of named subpatterns, the size
1388        computation could be caused to overflow. This is now prevented by limiting
1389        the length of names to 32 characters, and the number of named subpatterns
1390        to 10,000.
1392    11. Subpatterns that are repeated with specific counts have to be replicated in
1393        the compiled pattern. The size of memory for this was computed from the
1394        length of the subpattern and the repeat count. The latter is limited to
1395        65535, but there was no limit on the former, meaning that integer overflow
1396        could in principle occur. The compiled length of a repeated subpattern is
1397        now limited to 30,000 bytes in order to prevent this.
1399    12. Added the optional facility to have named substrings with the same name.
1401    13. Added the ability to use a named substring as a condition, using the
1402        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1403        are numbers (not recommended). Forward references are permitted.
1405    14. Added forward references in named backreferences (if you see what I mean).
1407    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1408        pattern could run off the end of the subject. For example, the pattern
1409        "(?s)(.{1,5})"8 did this with the subject "ab".
1411    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1412        PCRE_CASELESS was set when matching characters that were quantified with ?
1413        or *.
1415    17. A character class other than a single negated character that had a minimum
1416        but no maximum quantifier - for example [ab]{6,} - was not handled
1417        correctly by pce_dfa_exec(). It would match only one character.
1419    18. A valid (though odd) pattern that looked like a POSIX character
1420        class but used an invalid character after [ (for example [[,abc,]]) caused
1421        pcre_compile() to give the error "Failed: internal error: code overflow" or
1422        in some cases to crash with a glibc free() error. This could even happen if
1423        the pattern terminated after [[ but there just happened to be a sequence of
1424        letters, a binary zero, and a closing ] in the memory that followed.
1426    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1427        over the years. Originally (before any Unicode support), just the bottom 8
1428        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1429        output from "man perlunicode" includes this:
1431          The regular expression compiler produces polymorphic opcodes.  That
1432          is, the pattern adapts to the data and automatically switches to
1433          the Unicode character scheme when presented with Unicode data--or
1434          instead uses a traditional byte scheme when presented with byte
1435          data.
1437        Sadly, a wide octal escape does not cause a switch, and in a string with
1438        no other multibyte characters, these octal escapes are treated as before.
1439        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1440        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1441        Unicode string.
1443        I have not perpetrated such confusion in PCRE. Up till now, it took just
1444        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1445        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1446        translate to the appropriate multibyte character.
1448    29. Applied some refactoring to reduce the number of warnings from Microsoft
1449        and Borland compilers. This has included removing the fudge introduced
1450        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1451        a warning about an unused variable.
1453    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1454        characters since release 4.0, because Perl (from release 5.004) does not.
1455        [Or at least, is documented not to: some releases seem to be in conflict
1456        with the documentation.] However, when a pattern was studied with
1457        pcre_study() and all its branches started with \s, PCRE still included VT
1458        as a possible starting character. Of course, this did no harm; it just
1459        caused an unnecessary match attempt.
1461    22. Removed a now-redundant internal flag bit that recorded the fact that case
1462        dependency changed within the pattern. This was once needed for "required
1463        byte" processing, but is no longer used. This recovers a now-scarce options
1464        bit. Also moved the least significant internal flag bit to the most-
1465        significant bit of the word, which was not previously used (hangover from
1466        the days when it was an int rather than a uint) to free up another bit for
1467        the future.
1469    23. Added support for CRLF line endings as well as CR and LF. As well as the
1470        default being selectable at build time, it can now be changed at runtime
1471        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1472        specify that it is scanning data with non-default line endings.
1474    24. Changed the definition of CXXLINK to make it agree with the definition of
1475        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1477    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1478        recursions. This makes a big different to stack usage for some patterns.
1480    26. If a subpattern containing a named recursion or subroutine reference such
1481        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1482        the space required for the compiled pattern went wrong and gave too small a
1483        value. Depending on the environment, this could lead to "Failed: internal
1484        error: code overflow at offset 49" or "glibc detected double free or
1485        corruption" errors.
1487    27. Applied patches from Google (a) to support the new newline modes and (b) to
1488        advance over multibyte UTF-8 characters in GlobalReplace.
1490    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1491        difference for some implementation of PCRE in some Windows version.
1493    29. Added some extra testing facilities to pcretest:
1495        \q<number>   in a data line sets the "match limit" value
1496        \Q<number>   in a data line sets the "match recursion limt" value
1497        -S <number>  sets the stack size, where <number> is in megabytes
1499        The -S option isn't available for Windows.
1502    Version 6.6 06-Feb-06
1503    ---------------------
1505     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1506        in pcreposix.h. I have copied the definition from pcre.h.
1508     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1509        because pcre.h is no longer a built file.
1511     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1512        not normally included in the compiled code.
1515    Version 6.5 01-Feb-06
1516    ---------------------
1518     1. When using the partial match feature with pcre_dfa_exec(), it was not
1519        anchoring the second and subsequent partial matches at the new starting
1520        point. This could lead to incorrect results. For example, with the pattern
1521        /1234/, partially matching against "123" and then "a4" gave a match.
1523     2. Changes to pcregrep:
1525        (a) All non-match returns from pcre_exec() were being treated as failures
1526            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1527            error message is output. Some extra information is given for the
1528            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1529            probably the only errors that are likely to be caused by users (by
1530            specifying a regex that has nested indefinite repeats, for instance).
1531            If there are more than 20 of these errors, pcregrep is abandoned.
1533        (b) A binary zero was treated as data while matching, but terminated the
1534            output line if it was written out. This has been fixed: binary zeroes
1535            are now no different to any other data bytes.
1537        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1538            used to set a locale for matching. The --locale=xxxx long option has
1539            been added (no short equivalent) to specify a locale explicitly on the
1540            pcregrep command, overriding the environment variables.
1542        (d) When -B was used with -n, some line numbers in the output were one less
1543            than they should have been.
1545        (e) Added the -o (--only-matching) option.
1547        (f) If -A or -C was used with -c (count only), some lines of context were
1548            accidentally printed for the final match.
1550        (g) Added the -H (--with-filename) option.
1552        (h) The combination of options -rh failed to suppress file names for files
1553            that were found from directory arguments.
1555        (i) Added the -D (--devices) and -d (--directories) options.
1557        (j) Added the -F (--fixed-strings) option.
1559        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1561        (l) Added the --colo(u)r option.
1563        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1564            is not present by default.
1566     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1567        items such as (?R) or (?1), when the recursion could match a number of
1568        alternatives. If it matched one of the alternatives, but subsequently,
1569        outside the recursion, there was a failure, the code tried to back up into
1570        the recursion. However, because of the way PCRE is implemented, this is not
1571        possible, and the result was an incorrect result from the match.
1573        In order to prevent this happening, the specification of recursion has
1574        been changed so that all such subpatterns are automatically treated as
1575        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1577     4. I had overlooked the fact that, in some locales, there are characters for
1578        which isalpha() is true but neither isupper() nor islower() are true. In
1579        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1580        and ordfeminine) are like this. This affected the treatment of \w and \W
1581        when they appeared in character classes, but not when they appeared outside
1582        a character class. The bit map for "word" characters is now created
1583        separately from the results of isalnum() instead of just taking it from the
1584        upper, lower, and digit maps. (Plus the underscore character, of course.)
1586     5. The above bug also affected the handling of POSIX character classes such as
1587        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1588        permanent tables. Instead, the bit maps for such a class were previously
1589        created as the appropriate unions of the upper, lower, and digit bitmaps.
1590        Now they are created by subtraction from the [[:word:]] class, which has
1591        its own bitmap.
1593     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1594        It is created by subtracting the vertical space characters (\x09, \x0a,
1595        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1596        subtraction was done in the overall bitmap for a character class, meaning
1597        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1598        be recognized. This bug has been fixed.
1600     7. Patches from the folks at Google:
1602          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1603          real life, but is still worth protecting against".
1605          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1606          regular expressions".
1608          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1609          have it.
1611          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1612          "configure" and the latter not, in order to fix a problem somebody had
1613          with compiling the Arg class on HP-UX.
1615          (e) Improve the error-handling of the C++ wrapper a little bit.
1617          (f) New tests for checking recursion limiting.
1619     8. The pcre_memmove() function, which is used only if the environment does not
1620        have a standard memmove() function (and is therefore rarely compiled),
1621        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1622        returning a result (though PCRE never actually uses the result).
1624     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1625        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1626        returned instead of calling malloc() with an overflowing number that would
1627        most likely cause subsequent chaos.
1629    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1631    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1632        with this option is matched, the nmatch and pmatch options of regexec() are
1633        ignored.
1635    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1636        provided in case anyone wants to the the POSIX interface with UTF-8
1637        strings.
1639    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1640        C++ linking (needed for some HP-UX environments).
1642    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1643        (unused parameter) and in the pcre_printint() function (omitted "default"
1644        switch label when the default is to do nothing).
1646    15. Added some code to make it possible, when PCRE is compiled as a C++
1647        library, to replace subject pointers for pcre_exec() with a smart pointer
1648        class, thus making it possible to process discontinuous strings.
1650    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1651        much the same function. They were added by different people who were trying
1652        to make PCRE easy to compile on non-Unix systems. It has been suggested
1653        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1654        for compiling on Windows systems. I have therefore replaced it with
1655        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1656        defaults to "extern" for C or "extern C" for C++, which works fine on
1657        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1658        SCOPE with something explicit in config.h. In addition:
1660        (a) pcreposix.h still had just "extern" instead of either of these macros;
1661            I have replaced it with PCRE_DATA_SCOPE.
1663        (b) Functions such as _pcre_xclass(), which are internal to the library,
1664            but external in the C sense, all had PCRE_EXPORT in their definitions.
1665            This is apparently wrong for the Windows case, so I have removed it.
1666            (It makes no difference on Unix-like systems.)
1668    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1669        of recursive calls to match(). This is different to MATCH_LIMIT because
1670        that limits the total number of calls to match(), not all of which increase
1671        the depth of recursion. Limiting the recursion depth limits the amount of
1672        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1673        when PCRE is compiled, and changed at run time. A patch from Google adds
1674        this functionality to the C++ interface.
1676    18. Changes to the handling of Unicode character properties:
1678        (a) Updated the table to Unicode 4.1.0.
1680        (b) Recognize characters that are not in the table as "Cn" (undefined).
1682        (c) I revised the way the table is implemented to a much improved format
1683            which includes recognition of ranges. It now supports the ranges that
1684            are defined in UnicodeData.txt, and it also amalgamates other
1685            characters into ranges. This has reduced the number of entries in the
1686            table from around 16,000 to around 3,000, thus reducing its size
1687            considerably. I realized I did not need to use a tree structure after
1688            all - a binary chop search is just as efficient. Having reduced the
1689            number of entries, I extended their size from 6 bytes to 8 bytes to
1690            allow for more data.
1692        (d) Added support for Unicode script names via properties such as \p{Han}.
1694    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1695        matching that character.
1697    20. When matching a repeated Unicode property with a minimum greater than zero,
1698        (for example \pL{2,}), PCRE could look past the end of the subject if it
1699        reached it while seeking the minimum number of characters. This could
1700        happen only if some of the characters were more than one byte long, because
1701        there is a check for at least the minimum number of bytes.
1703    21. Refactored the implementation of \p and \P so as to be more general, to
1704        allow for more different types of property in future. This has changed the
1705        compiled form incompatibly. Anybody with saved compiled patterns that use
1706        \p or \P will have to recompile them.
1708    22. Added "Any" and "L&" to the supported property types.
1710    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1711        but give a compile time error if the value is greater than 0xff.
1713    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1714        accidentally not being installed or uninstalled.
1716    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1717        made were to insert the current release number. This seemed silly, because
1718        it made things harder for people building PCRE on systems that don't run
1719        "configure". I have turned pcre.h into a distributed file, no longer built
1720        by "configure", with the version identification directly included. There is
1721        no longer a pcre.h.in file.
1723        However, this change necessitated a change to the pcre-config script as
1724        well. It is built from pcre-config.in, and one of the substitutions was the
1725        release number. I have updated configure.ac so that ./configure now finds
1726        the release number by grepping pcre.h.
1728    26. Added the ability to run the tests under valgrind.
1731    Version 6.4 05-Sep-05
1732    ---------------------
1734     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1735        "--" to be printed when multiple files were scanned, even when none of the
1736        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1737        consider it to be a bug, and have restored the previous behaviour.
1739     2. A couple of code tidies to get rid of compiler warnings.
1741     3. The pcretest program used to cheat by referring to symbols in the library
1742        whose names begin with _pcre_. These are internal symbols that are not
1743        really supposed to be visible externally, and in some environments it is
1744        possible to suppress them. The cheating is now confined to including
1745        certain files from the library's source, which is a bit cleaner.
1747     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1748        file's purpose clearer.
1750     5. Reorganized pcre_ucp_findchar().
1753    Version 6.3 15-Aug-05
1754    ---------------------
1756     1. The file libpcre.pc.in did not have general read permission in the tarball.
1758     2. There were some problems when building without C++ support:
1760        (a) If C++ support was not built, "make install" and "make test" still
1761            tried to test it.
1763        (b) There were problems when the value of CXX was explicitly set. Some
1764            changes have been made to try to fix these, and ...
1766        (c) --disable-cpp can now be used to explicitly disable C++ support.
1768        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1769            backslash in a target when C++ was disabled. This confuses some
1770            versions of "make", apparently. Using an intermediate variable solves
1771            this. (Same for CPP_LOBJ.)
1773     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1774        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1775        necessary on certain architectures.
1777     4. Added a setting of -export-symbols-regex to the link command to remove
1778        those symbols that are exported in the C sense, but actually are local
1779        within the library, and not documented. Their names all begin with
1780        "_pcre_". This is not a perfect job, because (a) we have to except some
1781        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1782        available (and never for static libraries). I have made a note to try to
1783        find a way round (a) in the future.
1786    Version 6.2 01-Aug-05
1787    ---------------------
1789     1. There was no test for integer overflow of quantifier values. A construction
1790        such as {1111111111111111} would give undefined results. What is worse, if
1791        a minimum quantifier for a parenthesized subpattern overflowed and became
1792        negative, the calculation of the memory size went wrong. This could have
1793        led to memory overwriting.
1795     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1797     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1798        operating environments where this matters.
1800     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1801        PCRE options from within the C++ wrapper.
1803     5. Named capturing subpatterns were not being correctly counted when a pattern
1804        was compiled. This caused two problems: (a) If there were more than 100
1805        such subpatterns, the calculation of the memory needed for the whole
1806        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1807        back references of the form \12, where the number was greater than 9, were
1808        not recognized as back references, even though there were sufficient
1809        previous subpatterns.
1811     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1812        versions of gcc, e.g. 2.95.4.
1815    Version 6.1 21-Jun-05
1816    ---------------------
1818     1. There was one reference to the variable "posix" in pcretest.c that was not
1819        surrounded by "#if !defined NOPOSIX".
1821     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1822        the cross-check on the old pcre_info() function, for the benefit of the
1823        cut-down version of PCRE that is currently imported into Exim.
1825     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1826        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1827        patterns that start (?i) but I don't think that matters. The use of (?i) is
1828        just an example; this all applies to the other options as well.
1830     4. Since libtool seems to echo the compile commands it is issuing, the output
1831        from "make" can be reduced a bit by putting "@" in front of each libtool
1832        compile command.
1834     5. Patch from the folks at Google for configure.in to be a bit more thorough
1835        in checking for a suitable C++ installation before trying to compile the
1836        C++ stuff. This should fix a reported problem when a compiler was present,
1837        but no suitable headers.
1839     6. The man pages all had just "PCRE" as their title. I have changed them to
1840        be the relevant file name. I have also arranged that these names are
1841        retained in the file doc/pcre.txt, which is a concatenation in text format
1842        of all the man pages except the little individual ones for each function.
1844     7. The NON-UNIX-USE file had not been updated for the different set of source
1845        files that come with release 6. I also added a few comments about the C++
1846        wrapper.
1849    Version 6.0 07-Jun-05
1850    ---------------------
1852     1. Some minor internal re-organization to help with my DFA experiments.
1854     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1855        didn't matter for the library itself when fully configured, but did matter
1856        when compiling without UCP support, or within Exim, where the ucp files are
1857        not imported.
1859     3. Refactoring of the library code to split up the various functions into
1860        different source modules. The addition of the new DFA matching code (see
1861        below) to a single monolithic source would have made it really too
1862        unwieldy, quite apart from causing all the code to be include in a
1863        statically linked application, when only some functions are used. This is
1864        relevant even without the DFA addition now that patterns can be compiled in
1865        one application and matched in another.
1867        The downside of splitting up is that there have to be some external
1868        functions and data tables that are used internally in different modules of
1869        the library but which are not part of the API. These have all had their
1870        names changed to start with "_pcre_" so that they are unlikely to clash
1871        with other external names.
1873     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1874        a different (DFA) algorithm. Although it is slower than the original
1875        function, it does have some advantages for certain types of matching
1876        problem.
1878     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1879        including restarting after a partial match.
1881     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1882        defined when compiling for Windows was sent to me. I have put it into the
1883        code, though I have no means of testing or verifying it.
1885     7. Added the pcre_refcount() auxiliary function.
1887     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1888        match before or at the first newline in the subject string. In pcretest,
1889        the /f option on a pattern can be used to set this.
1891     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1892        would behave wrongly. This has been present in PCRE since release 4.0.
1894    10. A number of changes to the pcregrep command:
1896        (a) Refactored how -x works; insert ^(...)$ instead of setting
1897            PCRE_ANCHORED and checking the length, in preparation for adding
1898            something similar for -w.
1900        (b) Added the -w (match as a word) option.
1902        (c) Refactored the way lines are read and buffered so as to have more
1903            than one at a time available.
1905        (d) Implemented a pcregrep test script.
1907        (e) Added the -M (multiline match) option. This allows patterns to match
1908            over several lines of the subject. The buffering ensures that at least
1909            8K, or the rest of the document (whichever is the shorter) is available
1910            for matching (and similarly the previous 8K for lookbehind assertions).
1912        (f) Changed the --help output so that it now says
1914              -w, --word-regex(p)
1916            instead of two lines, one with "regex" and the other with "regexp"
1917            because that confused at least one person since the short forms are the
1918            same. (This required a bit of code, as the output is generated
1919            automatically from a table. It wasn't just a text change.)
1921        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1922            option but starts with a hyphen. Could be a pattern or a path name
1923            starting with a hyphen, for instance.
1925        (h) "-" can be given as a file name to represent stdin.
1927        (i) When file names are being printed, "(standard input)" is used for
1928            the standard input, for compatibility with GNU grep. Previously
1929            "<stdin>" was used.
1931        (j) The option --label=xxx can be used to supply a name to be used for
1932            stdin when file names are being printed. There is no short form.
1934        (k) Re-factored the options decoding logic because we are going to add
1935            two more options that take data. Such options can now be given in four
1936            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1938        (l) Added the -A, -B, and -C options for requesting that lines of context
1939            around matches be printed.
1941        (m) Added the -L option to print the names of files that do not contain
1942            any matching lines, that is, the complement of -l.
1944        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1945            continue to scan other files.
1947        (o) The -s option was incorrectly implemented. For compatibility with other
1948            greps, it now suppresses the error message for a non-existent or non-
1949            accessible file (but not the return code). There is a new option called
1950            -q that suppresses the output of matching lines, which was what -s was
1951            previously doing.
1953        (p) Added --include and --exclude options to specify files for inclusion
1954            and exclusion when recursing.
1956    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1957        Hopefully, it now does.
1959    12. Missing cast in pcre_study().
1961    13. Added an "uninstall" target to the makefile.
1963    14. Replaced "extern" in the function prototypes in Makefile.in with
1964        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1965        world, but is set differently for Windows.
1967    15. Added a second compiling function called pcre_compile2(). The only
1968        difference is that it has an extra argument, which is a pointer to an
1969        integer error code. When there is a compile-time failure, this is set
1970        non-zero, in addition to the error test pointer being set to point to an
1971        error message. The new argument may be NULL if no error number is required
1972        (but then you may as well call pcre_compile(), which is now just a
1973        wrapper). This facility is provided because some applications need a
1974        numeric error indication, but it has also enabled me to tidy up the way
1975        compile-time errors are handled in the POSIX wrapper.
1977    16. Added VPATH=.libs to the makefile; this should help when building with one
1978        prefix path and installing with another. (Or so I'm told by someone who
1979        knows more about this stuff than I do.)
1981    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1982        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1983        match everything, including newlines. This is not POSIX-compatible, but
1984        somebody wanted the feature. From pcretest it can be activated by using
1985        both the P and the s flags.
1987    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1989    19. libpcre.pc was being incorrectly installed as executable.
1991    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1992        it now also looks for '\r' so that it will work unmodified on Windows.
1994    21. Added Google's contributed C++ wrapper to the distribution.
1996    22. Added some untidy missing memory free() calls in pcretest, to keep
1997        Electric Fence happy when testing.
2001    Version 5.0 13-Sep-04
2002    ---------------------
2004     1. Internal change: literal characters are no longer packed up into items
2005        containing multiple characters in a single byte-string. Each character
2006        is now matched using a separate opcode. However, there may be more than one
2007        byte in the character in UTF-8 mode.
2009     2. The pcre_callout_block structure has two new fields: pattern_position and
2010        next_item_length. These contain the offset in the pattern to the next match
2011        item, and its length, respectively.
2013     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
2014        insertion of callouts before each pattern item. Added the /C option to
2015        pcretest to make use of this.
2017     4. On the advice of a Windows user, the lines
2019          #if defined(_WIN32) || defined(WIN32)
2020          _setmode( _fileno( stdout ), 0x8000 );
2021          #endif  /* defined(_WIN32) || defined(WIN32) */
2023        have been added to the source of pcretest. This apparently does useful
2024        magic in relation to line terminators.
2026     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
2027        for the benefit of those environments where the "b" makes a difference.
2029     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
2030        to know about it. I have put a hack into configure.in that adds in code
2031        to set GCC=yes if CC=icc. This seems to end up at a point in the
2032        generated configure script that is early enough to affect the setting of
2033        compiler options, which is what is needed, but I have no means of testing
2034        whether it really works. (The user who reported this had patched the
2035        generated configure script, which of course I cannot do.)
2037        LATER: After change 22 below (new libtool files), the configure script
2038        seems to know about icc (and also ecc). Therefore, I have commented out
2039        this hack in configure.in.
2041     7. Added support for pkg-config (2 patches were sent in).
2043     8. Negated POSIX character classes that used a combination of internal tables
2044        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
2045        [[:^ascii]]. Typically, they would match almost any characters. The other
2046        POSIX classes were not broken in this way.
2048     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
2049        to find the match, as PCRE was deluded into thinking that the match had to
2050        start at the start point or following a newline. The same bug applied to
2051        patterns with negative forward assertions or any backward assertions
2052        preceding ".*" at the start, unless the pattern required a fixed first
2053        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
2055    10. In UTF-8 mode, when moving forwards in the subject after a failed match
2056        starting at the last subject character, bytes beyond the end of the subject
2057        string were read.
2059    11. Renamed the variable "class" as "classbits" to make life easier for C++
2060        users. (Previously there was a macro definition, but it apparently wasn't
2061        enough.)
2063    12. Added the new field "tables" to the extra data so that tables can be passed
2064        in at exec time, or the internal tables can be re-selected. This allows
2065        a compiled regex to be saved and re-used at a later time by a different
2066        program that might have everything at different addresses.
2068    13. Modified the pcre-config script so that, when run on Solaris, it shows a
2069        -R library as well as a -L library.
2071    14. The debugging options of pcretest (-d on the command line or D on a
2072        pattern) showed incorrect output for anything following an extended class
2073        that contained multibyte characters and which was followed by a quantifier.
2075    15. Added optional support for general category Unicode character properties
2076        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
2077        support. It adds about 90K to the size of the library. The meanings of the
2078        inbuilt class escapes such as \d and \s have NOT been changed.
2080    16. Updated pcredemo.c to include calls to free() to release the memory for the
2081        compiled pattern.
2083    17. The generated file chartables.c was being created in the source directory
2084        instead of in the building directory. This caused the build to fail if the
2085        source directory was different from the building directory, and was
2086        read-only.
2088    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
2089        file. No doubt somebody will tell me if they don't make sense... Also added
2090        Dan Mooney's comments about building on OpenVMS.
2092    19. Added support for partial matching via the PCRE_PARTIAL option for
2093        pcre_exec() and the \P data escape in pcretest.
2095    20. Extended pcretest with 3 new pattern features:
2097        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
2098              write the compiled pattern to the file whose name is "rest-of-line".
2099              This is a straight binary dump of the data, with the saved pointer to
2100              the character tables forced to be NULL. The study data, if any, is
2101              written too. After writing, pcretest reads a new pattern.
2103        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
2104              compiled pattern from the given file. There must not be any
2105              occurrences of "<" in the file name (pretty unlikely); if there are,
2106              pcretest will instead treat the initial "<" as a pattern delimiter.
2107              After reading in the pattern, pcretest goes on to read data lines as
2108              usual.
2110        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
2111              and 16-bit fields in a compiled pattern, to simulate a pattern that
2112              was compiled on a host of opposite endianness.
2114    21. The pcre-exec() function can now cope with patterns that were compiled on
2115        hosts of opposite endianness, with this restriction:
2117          As for any compiled expression that is saved and used later, the tables
2118          pointer field cannot be preserved; the extra_data field in the arguments
2119          to pcre_exec() should be used to pass in a tables address if a value
2120          other than the default internal tables were used at compile time.
2122    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
2123        now diagnosed as an error. Previously, most of the time, a negative number
2124        would have been treated as zero, but if in addition "ovector" was passed as
2125        NULL, a crash could occur.
2127    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
2128        new versions from the libtool 1.5 distribution (the last one is a copy of
2129        a file called libtool.m4). This seems to have fixed the need to patch
2130        "configure" to support Darwin 1.3 (which I used to do). However, I still
2131        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
2132        workstation).
2134    24. Changed the PCRE licence to be the more standard "BSD" licence.
2137    Version 4.5 01-Dec-03
2138    ---------------------
2140     1. There has been some re-arrangement of the code for the match() function so
2141        that it can be compiled in a version that does not call itself recursively.
2142        Instead, it keeps those local variables that need separate instances for
2143        each "recursion" in a frame on the heap, and gets/frees frames whenever it
2144        needs to "recurse". Keeping track of where control must go is done by means
2145        of setjmp/longjmp. The whole thing is implemented by a set of macros that
2146        hide most of the details from the main code, and operates only if
2147        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
2148        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
2149        operating.
2151        To make it easier for callers to provide specially tailored get/free
2152        functions for this usage, two new functions, pcre_stack_malloc, and
2153        pcre_stack_free, are used. They are always called in strict stacking order,
2154        and the size of block requested is always the same.
2156        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
2157        PCRE has been compiled to use the stack or the heap for recursion. The
2158        -C option of pcretest uses this to show which version is compiled.
2160        A new data escape \S, is added to pcretest; it causes the amounts of store
2161        obtained and freed by both kinds of malloc/free at match time to be added
2162        to the output.
2164     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
2165        what's available on my current Linux desktop machine.
2167     3. When matching a UTF-8 string, the test for a valid string at the start has
2168        been extended. If start_offset is not zero, PCRE now checks that it points
2169        to a byte that is the start of a UTF-8 character. If not, it returns
2170        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
2171        this is necessary because there may be backward assertions in the pattern.
2172        When matching the same subject several times, it may save resources to use
2173        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
2175     4. The code for checking the validity of UTF-8 strings has been tightened so
2176        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
2177        containing "overlong sequences".
2179     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
2180        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
2181        should have been "&", but it just so happened that all the cases this let
2182        through by mistake were picked up later in the function.
2184     6. I had used a variable called "isblank" - this is a C99 function, causing
2185        some compilers to warn. To avoid this, I renamed it (as "blankclass").
2187     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
2188        prompting; (b) run "./pcretest /dev/null" at the start of the test script
2189        so the version is shown; (c) stop "make test" echoing "./RunTest".
2191     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
2193     9. The prototype for memmove() for systems that don't have it was using
2194        size_t, but the inclusion of the header that defines size_t was later. I've
2195        moved the #includes for the C headers earlier to avoid this.
2197    10. Added some adjustments to the code to make it easier to compiler on certain
2198        special systems:
2200          (a) Some "const" qualifiers were missing.
2201          (b) Added the macro EXPORT before all exported functions; by default this
2202              is defined to be empty.
2203          (c) Changed the dftables auxiliary program (that builds chartables.c) so
2204              that it reads its output file name as an argument instead of writing
2205              to the standard output and assuming this can be redirected.
2207    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
2208        class containing characters with values greater than 255, PCRE compilation
2209        went into a loop.
2211    12. A recursive reference to a subpattern that was within another subpattern
2212        that had a minimum quantifier of zero caused PCRE to crash. For example,
2213        (x(y(?2))z)? provoked this bug with a subject that got as far as the
2214        recursion. If the recursively-called subpattern itself had a zero repeat,
2215        that was OK.
2217    13. In pcretest, the buffer for reading a data line was set at 30K, but the
2218        buffer into which it was copied (for escape processing) was still set at
2219        1024, so long lines caused crashes.
2221    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
2222        "internal error: code overflow...". This applied to any character class
2223        that was followed by a possessive quantifier.
2225    15. Modified the Makefile to add libpcre.la as a prerequisite for
2226        libpcreposix.la because I was told this is needed for a parallel build to
2227        work.
2229    16. If a pattern that contained .* following optional items at the start was
2230        studied, the wrong optimizing data was generated, leading to matching
2231        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
2232        matching string must start with a or b or c. The correct conclusion for
2233        this pattern is that a match can start with any character.
2236    Version 4.4 13-Aug-03
2237    ---------------------
2239     1. In UTF-8 mode, a character class containing characters with values between
2240        127 and 255 was not handled correctly if the compiled pattern was studied.
2241        In fixing this, I have also improved the studying algorithm for such
2242        classes (slightly).
2244     2. Three internal functions had redundant arguments passed to them. Removal
2245        might give a very teeny performance improvement.
2247     3. Documentation bug: the value of the capture_top field in a callout is *one
2248        more than* the number of the hightest numbered captured substring.
2250     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
2251        in incorrectly linking with a previously installed version. They now link
2252        explicitly with libpcre.la.
2254     5. configure.in no longer needs to recognize Cygwin specially.
2256     6. A problem in pcre.in for Windows platforms is fixed.
2258     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
2259        pcretest, it used to include the size of the study block as part of its
2260        output. Unfortunately, the structure contains a field that has a different
2261        size on different hardware architectures. This meant that the tests that
2262        showed this size failed. As the block is currently always of a fixed size,
2263        this information isn't actually particularly useful in pcretest output, so
2264        I have just removed it.
2266     8. Three pre-processor statements accidentally did not start in column 1.
2267        Sadly, there are *still* compilers around that complain, even though
2268        standard C has not required this for well over a decade. Sigh.
2270     9. In pcretest, the code for checking callouts passed small integers in the
2271        callout_data field, which is a void * field. However, some picky compilers
2272        complained about the casts involved for this on 64-bit systems. Now
2273        pcretest passes the address of the small integer instead, which should get
2274        rid of the warnings.
2276    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
2277        both compile and run time, and gives an error if an invalid UTF-8 sequence
2278        is found. There is a option for disabling this check in cases where the
2279        string is known to be correct and/or the maximum performance is wanted.
2281    11. In response to a bug report, I changed one line in Makefile.in from
2283            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
2284        to
2285            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
2287        to look similar to other lines, but I have no way of telling whether this
2288        is the right thing to do, as I do not use Windows. No doubt I'll get told
2289        if it's wrong...
2292    Version 4.3 21-May-03
2293    ---------------------
2295    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
2296       Makefile.
2298    2. Some refactoring to improve the quality of the code:
2300       (i)   The utf8_table... variables are now declared "const".
2302       (ii)  The code for \cx, which used the "case flipping" table to upper case
2303             lower case letters, now just substracts 32. This is ASCII-specific,
2304             but the whole concept of \cx is ASCII-specific, so it seems
2305             reasonable.
2307       (iii) PCRE was using its character types table to recognize decimal and
2308             hexadecimal digits in the pattern. This is silly, because it handles
2309             only 0-9, a-f, and A-F, but the character types table is locale-
2310             specific, which means strange things might happen. A private
2311             table is now used for this - though it costs 256 bytes, a table is
2312             much faster than multiple explicit tests. Of course, the standard
2313             character types table is still used for matching digits in subject
2314             strings against \d.
2316       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
2317             ending in _t are). So I've renamed it as ESC_tee.
2319    3. The first argument for regexec() in the POSIX wrapper should have been
2320       defined as "const".
2322    4. Changed pcretest to use malloc() for its buffers so that they can be
2323       Electric Fenced for debugging.
2325    5. There were several places in the code where, in UTF-8 mode, PCRE would try
2326       to read one or more bytes before the start of the subject string. Often this
2327       had no effect on PCRE's behaviour, but in some circumstances it could
2328       provoke a segmentation fault.
2330    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
2331       to try to read one or more bytes before the start of the subject string.
2333    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
2334       UTF-8 support could misbehave in various ways if the subject string
2335       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
2336       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
2337       back over UTF-8 characters.)
2340    Version 4.2 14-Apr-03
2341    ---------------------
2343    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
2345    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
2346         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
2347         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
2348         [WIN_PREFIX]: new variable, "cyg" for Cygwin
2349         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
2350           and BUILD_EXEEXT
2351         Note: automatic setting of the BUILD variables is not yet working
2352         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
2353           compile-time but not at link-time
2354         [LINK]: use for linking executables only
2355         make different versions for Windows and non-Windows
2356         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
2357           libraries
2358         [LINK_FOR_BUILD]: new variable
2359         [OBJEXT]: use throughout
2360         [EXEEXT]: use throughout
2361         <winshared>: new target
2362         <wininstall>: new target
2363         <dftables.o>: use native compiler
2364         <dftables>: use native linker
2365         <install>: handle Windows platform correctly
2366         <clean>: ditto
2367         <check>: ditto
2368         copy DLL to top builddir before testing
2370       As part of these changes, -no-undefined was removed again. This was reported
2371       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
2372       in any case.
2374    3. Some tidies to get rid of compiler warnings:
2376       . In the match_data structure, match_limit was an unsigned long int, whereas
2377         match_call_count was an int. I've made them both unsigned long ints.
2379       . In pcretest the fact that a const uschar * doesn't automatically cast to
2380         a void * provoked a warning.
2382       . Turning on some more compiler warnings threw up some "shadow" variables
2383         and a few more missing casts.
2385    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
2386       option, a class that contained a single character with a value between 128
2387       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
2389    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
2390       option, a class that contained several characters, but with at least one
2391       whose value was between 128 and 255 caused PCRE to crash.
2394    Version 4.1 12-Mar-03
2395    ---------------------
2397    1. Compiling with gcc -pedantic found a couple of places where casts were
2398    needed, and a string in dftables.c that was longer than standard compilers are
2399    required to support.
2401    2. Compiling with Sun's compiler found a few more places where the code could
2402    be tidied up in order to avoid warnings.
2404    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
2405    first of these names is deprecated in the latest Autoconf in favour of the name
2406    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
2407    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
2408    analogy I have changed it to CFLAGS_FOR_BUILD.
2410    4. Added -no-undefined to the linking command in the Makefile, because this is
2411    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2412    linking step for the pcreposix library.
2414    5. PCRE was failing to diagnose the case of two named groups with the same
2415    name.
2417    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2418    literal character that is needed in the subject for a match, and scans along to
2419    ensure that it is present before embarking on the full matching process. This
2420    saves time in cases of nested unlimited repeats that are never going to match.
2421    Problem: the scan can take a lot of time if the subject is very long (e.g.
2422    megabytes), thus penalizing straightforward matches. It is now done only if the
2423    amount of subject to be scanned is less than 1000 bytes.
2425    7. A lesser problem with the same optimization is that it was recording the
2426    first character of an anchored pattern as "needed", thus provoking a search
2427    right along the subject, even when the first match of the pattern was going to
2428    fail. The "needed" character is now not set for anchored patterns, unless it
2429    follows something in the pattern that is of non-fixed length. Thus, it still
2430    fulfils its original purpose of finding quick non-matches in cases of nested
2431    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2434    Version 4.0 17-Feb-03
2435    ---------------------
2437    1. If a comment in an extended regex that started immediately after a meta-item
2438    extended to the end of string, PCRE compiled incorrect data. This could lead to
2439    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2441    2. Moved to autoconf 2.53 and libtool 1.4.2.
2443    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2444    the special perltest8 script is no longer needed - all the tests can be run
2445    from a single perltest script.
2447    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2448    by \s. It has now been removed in PCRE. This means it isn't recognized as
2449    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2450    class [:space:] *does* include VT, thereby creating a mess.
2452    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2453    space and tab.
2455    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2456    its new features into the main test script, reducing the number of scripts.
2458    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2459    were backward compatible, and made the (?i) apply to the whole pattern, as if
2460    /i were given. Now it behaves more logically, and applies the option setting
2461    only to what follows. PCRE has been changed to follow suit. However, if it
2462    finds options settings right at the start of the pattern, it extracts them into
2463    the global options, as before. Thus, they show up in the info data.
2465    8. Added support for the \Q...\E escape sequence. Characters in between are
2466    treated as literals. This is slightly different from Perl in that $ and @ are
2467    also handled as literals inside the quotes. In Perl, they will cause variable
2468    interpolation. Note the following examples:
2470        Pattern            PCRE matches      Perl matches
2472        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2473        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2474        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2476    For compatibility with Perl, \Q...\E sequences are recognized inside character
2477    classes as well as outside them.
2479    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2480    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2481    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2482    signed/unsigned warnings.
2484    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2485    option for pcretest, so I've replaced it by a simple function that does just
2486    that job.
2488    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2489    "pcregrep -".
2491    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2492    Java package. This provides some syntactic sugar for simple cases of what my
2493    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2494    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2495    item, you can use this simplified notation. Note that only makes sense with
2496    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2497    greediness, whatever the setting of the PCRE_UNGREEDY option.
2499    13. A change of greediness default within a pattern was not taking effect at
2500    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2501    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2502    was abstracted outside.
2504    14. PCRE now supports the \G assertion. It is true when the current matching
2505    position is at the start point of the match. This differs from \A when the
2506    starting offset is non-zero. Used with the /g option of pcretest (or similar
2507    code), it works in the same way as it does for Perl's /g option. If all
2508    alternatives of a regex begin with \G, the expression is anchored to the start
2509    match position, and the "anchored" flag is set in the compiled expression.
2511    15. Some bugs concerning the handling of certain option changes within patterns
2512    have been fixed. These applied to options other than (?ims). For example,
2513    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2514    been the other way round. Some of this was related to change 7 above.
2516    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2517    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2518    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2519    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2521    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2522    mode. Unlike ".", it always matches newline, whatever the setting of
2523    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2524    assertions. Perl allows it, but it doesn't (in general) work because it can't
2525    calculate the length of the lookbehind. At least, that's the case for Perl
2526    5.8.0 - I've been told they are going to document that it doesn't work in
2527    future.
2529    18. Added an error diagnosis for escapes that PCRE does not support: these are
2530    \L, \l, \N, \P, \p, \U, \u, and \X.
2532    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2533    reading past the end of the pattern in cases such as /[abcd/.
2535    20. PCRE was getting more memory than necessary for patterns with classes that
2536    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2538    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2539    compiling PCRE for use with Virtual Pascal.
2541    22. Small fix to the Makefile to make it work properly if the build is done
2542    outside the source tree.
2544    23. Added a new extension: a condition to go with recursion. If a conditional
2545    subpattern starts with (?(R) the "true" branch is used if recursion has
2546    happened, whereas the "false" branch is used only at the top level.
2548    24. When there was a very long string of literal characters (over 255 bytes
2549    without UTF support, over 250 bytes with UTF support), the computation of how
2550    much memory was required could be incorrect, leading to segfaults or other
2551    strange effects.
2553    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2554    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2555    there was a subsequent back reference to those brackets. This meant that, for
2556    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2557    possible to check for precisely this case. All we can do is abandon the
2558    optimization if .* occurs inside capturing brackets when there are any back
2559    references whatsoever. (See below for a better fix that came later.)
2561    26. The handling of the optimization for finding the first character of a
2562    non-anchored pattern, and for finding a character that is required later in the
2563    match were failing in some cases. This didn't break the matching; it just
2564    failed to optimize when it could. The way this is done has been re-implemented.
2566    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2568    28. Added a new feature that provides some of the functionality that Perl
2569    provides with (?{...}). The facility is termed a "callout". The way it is done
2570    in PCRE is for the caller to provide an optional function, by setting
2571    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2572    global variable. By default it is unset, which disables all calling out. To get
2573    the function called, the regex must include (?C) at appropriate points. This
2574    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2575    This provides a means of identifying different callout points. When PCRE
2576    reaches such a point in the regex, if pcre_callout has been set, the external
2577    function is called. It is provided with data in a structure called
2578    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2579    matching continues; if it returns a non-zero value, the match at the current
2580    point fails. However, backtracking will occur if possible. [This was changed
2581    later and other features added - see item 49 below.]
2583    29. pcretest is upgraded to test the callout functionality. It provides a
2584    callout function that displays information. By default, it shows the start of
2585    the match and the current position in the text. There are some new data escapes
2586    to vary what happens:
2588        \C+         in addition, show current contents of captured substrings
2589        \C-         do not supply a callout function
2590        \C!n        return 1 when callout number n is reached
2591        \C!n!m      return 1 when callout number n is reached for the mth time
2593    30. If pcregrep was called with the -l option and just a single file name, it
2594    output "<stdin>" if a match was found, instead of the file name.
2596    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2597    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2598    pcre_exec(). This saves a malloc/free per call. The default value of
2599    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2600    when configuring.
2602    32. The default maximum size of a compiled pattern is 64K. There have been a
2603    few cases of people hitting this limit. The code now uses macros to handle the
2604    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2605    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2606    configuring. Tests 2 and 5 work only with 2-byte links because they output
2607    debugging information about compiled patterns.
2609    33. Internal code re-arrangements:
2611    (a) Moved the debugging function for printing out a compiled regex into
2612        its own source file (printint.c) and used #include to pull it into
2613        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2614        separate copies.
2616    (b) Defined the list of op-code names for debugging as a macro in
2617        internal.h so that it is next to the definition of the opcodes.
2619    (c) Defined a table of op-code lengths for simpler skipping along compiled
2620        code. This is again a macro in internal.h so that it is next to the
2621        definition of the opcodes.
2623    34. Added support for recursive calls to individual subpatterns, along the
2624    lines of Robin Houston's patch (but implemented somewhat differently).
2626    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2627    allow it to read and process whole directories in Win32. This code was
2628    contributed by Lionel Fourquaux; it has not been tested by me.
2630    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2631    used to name a group. Names consist of alphanumerics and underscores, and must
2632    be unique. Back references use the syntax (?P=name) and recursive calls use
2633    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2634    numbers. The function pcre_fullinfo() can be used after compilation to extract
2635    a name/number map. There are three relevant calls:
2637      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2638      PCRE_INFO_NAMECOUNT            yields the number of entries
2639      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2641    The map is a vector of fixed-size entries. The size of each entry depends on
2642    the length of the longest name used. The first two bytes of each entry are the
2643    group number, most significant byte first. There follows the corresponding
2644    name, zero terminated. The names are in alphabetical order.
2646    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2647    case instead of 255. Making it the same both with and without UTF-8 support
2648    means that the same test output works with both.
2650    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2651    calling malloc() with a zero argument.
2653    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2654    optimization. I've improved things by keeping a bitmap of backreferences with
2655    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2656    fact referenced, the optimization can be applied. It is unlikely that a
2657    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2658    the match to follow \n) will appear inside brackets with a number greater than
2659    31, but if it does, any back reference > 31 suppresses the optimization.
2661    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2662    of disabling numbered capturing parentheses. Any opening parenthesis that is
2663    not followed by ? behaves as if it were followed by ?: but named parentheses
2664    can still be used for capturing (and they will acquire numbers in the usual
2665    way).
2667    41. Redesigned the return codes from the match() function into yes/no/error so
2668    that errors can be passed back from deep inside the nested calls. A malloc
2669    failure while inside a recursive subpattern call now causes the
2670    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2672    42. It is now possible to set a limit on the number of times the match()
2673    function is called in a call to pcre_exec(). This facility makes it possible to
2674    limit the amount of recursion and backtracking, though not in a directly
2675    obvious way, because the match() function is used in a number of different
2676    circumstances. The count starts from zero for each position in the subject
2677    string (for non-anchored patterns). The default limit is, for compatibility, a
2678    large number, namely 10 000 000. You can change this in two ways:
2680    (a) When configuring PCRE before making, you can use --with-match-limit=n
2681        to set a default value for the compiled library.
2683    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2684        a different value is set. See 45 below.
2686    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2688    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2689    of things that can be changed at compile time. The first argument specifies
2690    what is wanted and the second points to where the information is to be placed.
2691    The current list of available information is:
2693      PCRE_CONFIG_UTF8
2695    The output is an integer that is set to one if UTF-8 support is available;
2696    otherwise it is set to zero.
2700    The output is an integer that it set to the value of the code that is used for
2701    newline. It is either LF (10) or CR (13).
2705    The output is an integer that contains the number of bytes used for internal
2706    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2710    The output is an integer that contains the threshold above which the POSIX
2711    interface uses malloc() for output vectors. See item 31 above.
2715    The output is an unsigned integer that contains the default limit of the number
2716    of match() calls in a pcre_exec() execution. See 42 above.
2718    44. pcretest has been upgraded by the addition of the -C option. This causes it
2719    to extract all the available output from the new pcre_config() function, and to
2720    output it. The program then exits immediately.
2722    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2723    order to support additional features. One way would have been to define
2724    pcre_exec2() (for example) with extra arguments, but this would not have been
2725    extensible, and would also have required all calls to the original function to
2726    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2727    is used for passing in "extra" data from pcre_study().
2729    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2730    contains the following fields:
2732      flags         a bitmap indicating which of the following fields are set
2733      study_data    opaque data from pcre_study()
2734      match_limit   a way of specifying a limit on match() calls for a specific
2735                      call to pcre_exec()
2736      callout_data  data for callouts (see 49 below)
2738    The flag bits are also defined in pcre.h, and are
2744    The pcre_study() function now returns one of these new pcre_extra blocks, with
2745    the actual study data pointed to by the study_data field, and the
2746    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2747    before. That is, this change is entirely upwards-compatible and requires no
2748    change to existing code.
2750    If you want to pass in additional data to pcre_exec(), you can either place it
2751    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2752    block.
2754    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2755    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2756    times with different match limits, until it finds the minimum value needed for
2757    pcre_exec() to complete. The value is then output. This can be instructive; for
2758    most simple matches the number is quite small, but for pathological cases it
2759    gets very large very quickly.
2761    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2762    returns the size of the data block pointed to by the study_data field in a
2763    pcre_extra block, that is, the value that was passed as the argument to
2764    pcre_malloc() when PCRE was getting memory in which to place the information
2765    created by pcre_study(). The fourth argument should point to a size_t variable.
2766    pcretest has been extended so that this information is shown after a successful
2767    pcre_study() call when information about the compiled regex is being displayed.
2769    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2770    because what follows is always an absolute path. (Later: it turns out that this
2771    is more than cosmetic for MinGW, because it doesn't like empty path
2772    components.)
2774    49. Some changes have been made to the callout feature (see 28 above):
2776    (i)  A callout function now has three choices for what it returns:
2778           0  =>  success, carry on matching
2779         > 0  =>  failure at this point, but backtrack if possible
2780         < 0  =>  serious error, return this value from pcre_exec()
2782         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2783         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2784         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2785         use by callout functions. It will never be used by PCRE itself.
2787    (ii) The pcre_extra structure (see 45 above) has a void * field called
2788         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2789         pcre_callout_block structure has a field of the same name. The contents of
2790         the field passed in the pcre_extra structure are passed to the callout
2791         function in the corresponding field in the callout block. This makes it
2792         easier to use the same callout-containing regex from multiple threads. For
2793         testing, the pcretest program has a new data escape
2795           \C*n        pass the number n (may be negative) as callout_data
2797         If the callout function in pcretest receives a non-zero value as
2798         callout_data, it returns that value.
2800    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2801    there were some redundant $(CFLAGS) in commands that are now specified as
2802    $(LINK), which already includes $(CFLAGS).
2804    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2805    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2806    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2807    one-byte characters throughout. Note that case-insensitive matching applies
2808    only to characters whose values are less than 256. PCRE doesn't support the
2809    notion of cases for higher-valued characters.
2811    (i)   A character class whose characters are all within 0-255 is handled as
2812          a bit map, and the map is inverted for negative classes. Previously, a
2813          character > 255 always failed to match such a class; however it should
2814          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2816    (ii)  A negated character class with a single character < 255 is coded as
2817          "not this character" (OP_NOT). This wasn't working properly when the test
2818          character was multibyte, either singly or repeated.
2820    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2821          mode, for example: \x{100}{2,3}.
2823    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2824          singly or repeated) now correctly test multibyte characters. However,
2825          PCRE doesn't recognize any characters with values greater than 255 as
2826          digits, spaces, or word characters. Such characters always match \D, \S,
2827          and \W, and never match \d, \s, or \w.
2829    (v)   Classes may now contain characters and character ranges with values
2830          greater than 255. For example: [ab\x{100}-\x{400}].
2832    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2833          PCRE in UTF-8 mode.
2835    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2836    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2837    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2838    value.)
2840    53. The single man page has become too large. I have therefore split it up into
2841    a number of separate man pages. These also give rise to individual HTML pages;
2842    these are now put in a separate directory, and there is an index.html page that
2843    lists them all. Some hyperlinking between the pages has been installed.
2845    54. Added convenience functions for handling named capturing parentheses.
2847    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2848    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2849    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2850    are faulted.
2852    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2853    calling configure. These values are used when compiling the dftables.c program
2854    which is run to generate the source of the default character tables. They
2855    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2856    you will need to set these values.
2858    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2861    Version 3.9 02-Jan-02
2862    ---------------------
2864    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2866    2. If --disable-static was given, the building process failed when trying to
2867    build pcretest and pcregrep. (For some reason it was using libtool to compile
2868    them, which is not right, as they aren't part of the library.)
2871    Version 3.8 18-Dec-01
2872    ---------------------
2874    1. The experimental UTF-8 code was completely screwed up. It was packing the
2875    bytes in the wrong order. How dumb can you get?
2878    Version 3.7 29-Oct-01
2879    ---------------------
2881    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2882    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2883    this didn't happen under Solaris 8, where I normally test things.
2885    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2886    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2887    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2888    this fix an hour or so after the initial 3.7 release.)
2891    Version 3.6 23-Oct-01
2892    ---------------------
2894    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2895    offsets passed as NULL with zero offset count.
2897    2. The config.guess and config.sub files had not been updated when I moved to
2898    the latest autoconf.
2901    Version 3.5 15-Aug-01
2902    ---------------------
2904    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2905    had been forgotten.
2907    2. By using declared but undefined structures, we can avoid using "void"
2908    definitions in pcre.h while keeping the internal definitions of the structures
2909    private.
2911    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2912    user point of view, this means that both static and shared libraries are built
2913    by default, but this can be individually controlled. More of the work of
2914    handling this static/shared cases is now inside libtool instead of PCRE's make
2915    file.
2917    4. The pcretest utility is now installed along with pcregrep because it is
2918    useful for users (to test regexs) and by doing this, it automatically gets
2919    relinked by libtool. The documentation has been turned into a man page, so
2920    there are now .1, .txt, and .html versions in /doc.
2922    5. Upgrades to pcregrep:
2923       (i)   Added long-form option names like gnu grep.
2924       (ii)  Added --help to list all options with an explanatory phrase.
2925       (iii) Added -r, --recursive to recurse into sub-directories.
2926       (iv)  Added -f, --file to read patterns from a file.
2928    6. pcre_exec() was referring to its "code" argument before testing that
2929    argument for NULL (and giving an error if it was NULL).
2931    7. Upgraded Makefile.in to allow for compiling in a different directory from
2932    the source directory.
2934    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2935    options bits, the pointer it was passed was to an int instead of to an unsigned
2936    long int. This mattered only on 64-bit systems.
2938    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2939    generated) instead of pcre.in, which it its source. Also made the same change
2940    in several of the .c files.
2942    10. A new release of gcc defines printf() as a macro, which broke pcretest
2943    because it had an ifdef in the middle of a string argument for printf(). Fixed
2944    by using separate calls to printf().
2946    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2947    script, to force use of CR or LF instead of \n in the source. On non-Unix
2948    systems, the value can be set in config.h.
2950    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2951    absolute limit. Changed the text of the error message to make this clear, and
2952    likewise updated the man page.
2954    13. The limit of 99 on the number of capturing subpatterns has been removed.
2955    The new limit is 65535, which I hope will not be a "real" limit.
2958    Version 3.4 22-Aug-00
2959    ---------------------
2961    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2963    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2966    Version 3.3 01-Aug-00
2967    ---------------------
2969    1. If an octal character was given, but the value was greater than \377, it
2970    was not getting masked to the least significant bits, as documented. This could
2971    lead to crashes in some systems.
2973    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2974    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2976    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2977    These just pass their arguments on to (pcre_free)(), but they are provided
2978    because some uses of PCRE bind it to non-C systems that can call its functions,
2979    but cannot call free() or pcre_free() directly.
2981    4. Add "make test" as a synonym for "make check". Corrected some comments in
2982    the Makefile.
2984    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2985    Makefile.
2987    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2988    command called pgrep for grepping around the active processes.
2990    7. Added the beginnings of support for UTF-8 character strings.
2992    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2993    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2994    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2995    out for the ar command.)
2998    Version 3.2 12-May-00
2999    ---------------------
3001    This is purely a bug fixing release.
3003    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
3004    of ZA. This was just one example of several cases that could provoke this bug,
3005    which was introduced by change 9 of version 2.00. The code for breaking
3006    infinite loops after an iteration that matches an empty string was't working
3007    correctly.
3009    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
3010    when matched against abbab (for example). After matching an empty string, it
3011    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
3012    caused it to match further down the string than it should.
3014    3. The code contained an inclusion of sys/types.h. It isn't clear why this
3015    was there because it doesn't seem to be needed, and it causes trouble on some
3016    systems, as it is not a Standard C header. It has been removed.
3018    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
3019    were reported on the Macintosh. The changes were from
3021      while ((c = *(++ptr)) != 0 && c != '\n');
3022    to
3023      while ((c = *(++ptr)) != 0 && c != '\n') ;
3025    Totally extraordinary, but if that's what it takes...
3027    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
3028    available. Added HAVE_BCOPY and an autoconf test for it; if neither
3029    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
3030    assumes the way PCRE uses memmove() (always moving upwards).
3032    6. PCRE is being used in one environment where strchr() is not available. There
3033    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
3034    faster code anyway.
3037    Version 3.1 09-Feb-00
3038    ---------------------
3040    The only change in this release is the fixing of some bugs in Makefile.in for
3041    the "install" target:
3043    (1) It was failing to install pcreposix.h.
3045    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
3048    Version 3.0 01-Feb-00
3049    ---------------------
3051    1. Add support for the /+ modifier to perltest (to output $` like it does in
3052    pcretest).
3054    2. Add support for the /g modifier to perltest.
3056    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
3057    matches null strings.
3059    4. Fix perltest so that it doesn't do unwanted things when fed an empty
3060    pattern. Perl treats empty patterns specially - it reuses the most recent
3061    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
3062    effect.
3064    5. The POSIX interface was broken in that it was just handing over the POSIX
3065    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
3066    required a bigger vector, with some working space on the end. This means that
3067    the POSIX wrapper now has to get and free some memory, and copy the results.
3069    6. Added some simple autoconf support, placing the test data and the
3070    documentation in separate directories, re-organizing some of the
3071    information files, and making it build pcre-config (a GNU standard). Also added
3072    libtool support for building PCRE as a shared library, which is now the
3073    default.
3075    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
3076    09 are not valid octal constants. Single digits will be used for minor values
3077    less than 10.
3079    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
3080    existing programs that set these in the POSIX interface can use PCRE without
3081    modification.
3083    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
3084    return all that pcre_info() returns, plus additional data. The pcre_info()
3085    function is retained for compatibility, but is considered to be obsolete.
3087    10. Added experimental recursion feature (?R) to handle one common case that
3088    Perl 5.6 will be able to do with (?p{...}).
3090    11. Added support for POSIX character classes like [:alpha:], which Perl is
3091    adopting.
3094    Version 2.08 31-Aug-99
3095    ----------------------
3097    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
3098    trying to match at the startoffset position, but instead was moving forward to
3099    the next newline as if a previous match had failed.
3101    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
3102    and could get into a loop if a null string was matched other than at the start
3103    of the subject.
3105    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
3106    be distinguished at compile time, and for completeness also added PCRE_DATE.
3108    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
3109    in GnuWin32 environments.
3112    Version 2.07 29-Jul-99
3113    ----------------------
3115    1. The documentation is now supplied in plain text form and HTML as well as in
3116    the form of man page sources.
3118    2. C++ compilers don't like assigning (void *) values to other pointer types.
3119    In particular this affects malloc(). Although there is no problem in Standard
3120    C, I've put in casts to keep C++ compilers happy.
3122    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
3123    should be (const char *).
3125    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
3126    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
3127    However, I haven't made this a standard facility. The documentation doesn't
3128    mention it, and the Makefile doesn't support it.
3130    5. The Makefile now contains an "install" target, with editable destinations at
3131    the top of the file. The pcretest program is not installed.
3133    6. pgrep -V now gives the PCRE version number and date.
3135    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
3136    causing the entire string to be ignored, instead of just the last character.
3138    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
3139    non-matching string, it can take a very, very long time, even for strings of
3140    quite modest length, because of the nested recursion. PCRE now does better in
3141    some of these cases. It does this by remembering the last required literal
3142    character in the pattern, and pre-searching the subject to ensure it is present
3143    before running the real match. In other words, it applies a heuristic to detect
3144    some types of certain failure quickly, and in the above example, if presented
3145    with a string that has no trailing " it gives "no match" very quickly.
3147    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
3148    other alternatives are tried instead.
3151    Version 2.06 09-Jun-99
3152    ----------------------
3154    1. Change pcretest's output for amount of store used to show just the code
3155    space, because the remainder (the data block) varies in size between 32-bit and
3156    64-bit systems.
3158    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
3159    start matching at. This allows lookbehinds to work when searching for multiple
3160    occurrences in a string.
3162    3. Added additional options to pcretest for testing multiple occurrences:
3164       /+   outputs the rest of the string that follows a match
3165       /g   loops for multiple occurrences, using the new startoffset argument
3166       /G   loops for multiple occurrences by passing an incremented pointer
3168    4. PCRE wasn't doing the "first character" optimization for patterns starting
3169    with \b or \B, though it was doing it for other lookbehind assertions. That is,
3170    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
3171    the letter 'x'. On long subject strings, this gives a significant speed-up.
3174    Version 2.05 21-Apr-99
3175    ----------------------
3177    1. Changed the type of magic_number from int to long int so that it works
3178    properly on 16-bit systems.
3180    2. Fixed a bug which caused patterns starting with .* not to work correctly
3181    when the subject string contained newline characters. PCRE was assuming
3182    anchoring for such patterns in all cases, which is not correct because .* will
3183    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
3184    DOTALL is set at top level; otherwise it knows that patterns starting with .*
3185    must be retried after every newline in the subject.
3188    Version 2.04 18-Feb-99
3189    ----------------------
3191    1. For parenthesized subpatterns with repeats whose minimum was zero, the
3192    computation of the store needed to hold the pattern was incorrect (too large).
3193    If such patterns were nested a few deep, this could multiply and become a real
3194    problem.
3196    2. Added /M option to pcretest to show the memory requirement of a specific
3197    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
3199    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
3200    compiled in such a way that the backtracking after subsequent failure was
3201    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
3202    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
3205    Version 2.03 02-Feb-99
3206    ----------------------
3208    1. Fixed typo and small mistake in man page.
3210    2. Added 4th condition (GPL supersedes if conflict) and created separate
3211    LICENCE file containing the conditions.
3213    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
3214    Perl, that is the internal \ allows the delimiter to be included in the
3215    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
3216    the final delimiter, add \ to the end of the pattern (to test the error).
3218    4. Added the convenience functions for extracting substrings after a successful
3219    match. Updated pcretest to make it able to test these functions.
3222    Version 2.02 14-Jan-99
3223    ----------------------
3225    1. Initialized the working variables associated with each extraction so that
3226    their saving and restoring doesn't refer to uninitialized store.
3228    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
3229    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
3230    fix the problem.
3232    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
3233    calls, and wasn't printing the correct value for compiling calls. Increased the
3234    default value of LOOPREPEAT, and the number of significant figures in the
3235    times.
3237    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
3239    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
3240    a building problem on Windows NT with a FAT file system.
3243    Version 2.01 21-Oct-98
3244    ----------------------
3246    1. Changed the API for pcre_compile() to allow for the provision of a pointer
3247    to character tables built by pcre_maketables() in the current locale. If NULL
3248    is passed, the default tables are used.
3251    Version 2.00 24-Sep-98
3252    ----------------------
3254    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
3255    it any more.
3257    2. Allow quantification of (?>) groups, and make it work correctly.
3259    3. The first character computation wasn't working for (?>) groups.
3261    4. Correct the implementation of \Z (it is permitted to match on the \n at the
3262    end of the subject) and add 5.005's \z, which really does match only at the
3263    very end of the subject.
3265    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
3267    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
3268    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
3269    localized options. All options to pcre_study() were also removed.
3271    7. Add other new features from 5.005:
3273       $(?<=           positive lookbehind
3274       $(?<!           negative lookbehind
3275       (?imsx-imsx)    added the unsetting capability
3276                       such a setting is global if at outer level; local otherwise
3277       (?imsx-imsx:)   non-capturing groups with option setting
3278       (?(cond)re|re)  conditional pattern matching
3280       A backreference to itself in a repeated group matches the previous
3281       captured string.
3283    8. General tidying up of studying (both automatic and via "study")
3284    consequential on the addition of new assertions.
3286    9. As in 5.005, unlimited repeated groups that could match an empty substring
3287    are no longer faulted at compile time. Instead, the loop is forcibly broken at
3288    runtime if any iteration does actually match an empty substring.
3290    10. Include the RunTest script in the distribution.
3292    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
3293    discrepancies, some of which were old and were also with respect to 5.004. They
3294    have now been fixed.
3297    Version 1.09 28-Apr-98
3298    ----------------------
3300    1. A negated single character class followed by a quantifier with a minimum
3301    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
3302    program crashes, or just wrong answers. This did not apply to negated classes
3303    containing more than one character, or to minima other than one.
3306    Version 1.08 27-Mar-98
3307    ----------------------
3309    1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
3311    2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
3312    latter must appear before anything that relies on it in the pattern.
3315  Version 1.07 16-Feb-98  Version 1.07 16-Feb-98
3316  ----------------------  ----------------------

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