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revision 61 by nigel, Sat Feb 24 21:39:58 2007 UTC revision 386 by ph10, Tue Mar 10 11:48:33 2009 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 3.0 02-Jan-02  Version 7.9 xx-xxx-09
5    ---------------------
7    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
8        (pcretest), all targets were linked against these libraries. This included
9        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
10        libraries. This caused unwanted dependencies to be created. This problem
11        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
12        pcretest is linked with readline.
14    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
15        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
16        moved outside it again, because FALSE and TRUE are already defined in AIX,
17        but BOOL is not.
19    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
20        PCRE_MATCH_LIMIT_RETURSION values as ints, when they should be long ints.
22    4.  The pcregrep documentation said spaces were inserted as well as colons (or
23        hyphens) following file names and line numbers when outputting matching
24        lines. This is not true; no spaces are inserted. I have also clarified the
25        wording for the --colour (or --color) option.
27    5.  In pcregrep, when --colour was used with -o, the list of matching strings
28        was not coloured; this is different to GNU grep, so I have changed it to be
29        the same.
31    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
32        each matching line was coloured. Now it goes on to look for further matches
33        of any of the test patterns, which is the same behaviour as GNU grep.
35    7.  A pattern that could match an empty string could cause pcregrep to loop; it
36        doesn't make sense to accept an empty string match in pcregrep, so I have
37        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
38        seems to be how GNU grep behaves.
40    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
41        start or after a newline", because the conditional assertion was not being
42        correctly handled. The rule now is that both the assertion and what follows
43        in the first alternative must satisfy the test.
45    9.  If auto-callout was enabled in a pattern with a conditional group, PCRE
46        could crash during matching.
48    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
49        used for matching.
51    11. Unicode property support in character classes was not working for
52        characters (bytes) greater than 127 when not in UTF-8 mode.
54    12. Added the -M command line option to pcretest.
57    Version 7.8 05-Sep-08
58    ---------------------
60    1.  Replaced UCP searching code with optimized version as implemented for Ad
61        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
62        stage table and inline lookup instead of a function, giving speed ups of 2
63        to 5 times on some simple patterns that I tested. Permission was given to
64        distribute the MultiStage2.py script that generates the tables (it's not in
65        the tarball, but is in the Subversion repository).
67    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
68        scripts.
70    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
71        a group with a zero qualifier. The result of the study could be incorrect,
72        or the function might crash, depending on the pattern.
74    4.  Caseless matching was not working for non-ASCII characters in back
75        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
76        It now works when Unicode Property Support is available.
78    5.  In pcretest, an escape such as \x{de} in the data was always generating
79        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
80        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
81        truncation.
83    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
85    7.  Added two (int) casts to pcregrep when printing the difference of two
86        pointers, in case they are 64-bit values.
88    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
89        test 2 if it fails.
91    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
92        and a #define of that name to empty if it is not externally set. This is to
93        allow users of MSVC to set it if necessary.
95    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
96        the convenience functions in the pcre_get.c source file.
98    11. An option change at the start of a pattern that had top-level alternatives
99        could cause overwriting and/or a crash. This command provoked a crash in
100        some environments:
102          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
104        This potential security problem was recorded as CVE-2008-2371.
106    12. For a pattern where the match had to start at the beginning or immediately
107        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
108        pcre_dfa_exec() could read past the end of the passed subject if there was
109        no match. To help with detecting such bugs (e.g. with valgrind), I modified
110        pcretest so that it places the subject at the end of its malloc-ed buffer.
112    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
113        exec() might read past the end of the data buffer in UTF-8 mode.
115    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
116        the data contained the byte 0x85 as part of a UTF-8 character within its
117        first line. This applied both to normal and DFA matching.
119    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
120        /^[^d]*?$/8 failed to match "abc".
122    16. Added a missing copyright notice to pcrecpp_internal.h.
124    17. Make it more clear in the documentation that values returned from
125        pcre_exec() in ovector are byte offsets, not character counts.
127    18. Tidied a few places to stop certain compilers from issuing warnings.
129    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
130        supplied by Stefan Weber. I made a further small update for 7.8 because
131        there is a change of source arrangements: the pcre_searchfuncs.c module is
132        replaced by pcre_ucd.c.
135    Version 7.7 07-May-08
136    ---------------------
138    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
139        a string to a long long, pretend we don't even have a long long." This is
140        done by checking for the strtoq, strtoll, and _strtoi64 functions.
142    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
143        pre-7.6 versions, which defined a global no_arg variable instead of putting
144        it in the RE class. (See also #8 below.)
146    3.  Remove a line of dead code, identified by coverity and reported by Nuno
147        Lopes.
149    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
151        (1) The include/exclude patterns were being applied to the whole pathnames
152            of files, instead of just to the final components.
154        (2) If there was more than one level of directory, the subdirectories were
155            skipped unless they satisfied the include/exclude conditions. This is
156            inconsistent with GNU grep (and could even be seen as contrary to the
157            pcregrep specification - which I improved to make it absolutely clear).
158            The action now is always to scan all levels of directory, and just
159            apply the include/exclude patterns to regular files.
161    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
162        --exclude_dir in the tests to avoid scanning .svn directories.
164    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
165        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
166        doesn't support NULs in patterns.
168    7.  Added some missing "const"s to declarations of static tables in
169        pcre_compile.c and pcre_dfa_exec.c.
171    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
172        caused by fix #2  above. (Subsequently also a second patch to fix the
173        first patch. And a third patch - this was a messy problem.)
175    9.  Applied Craig's patch to remove the use of push_back().
177    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
178        matching function regexec().
180    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
181        which, however, unlike Perl's \g{...}, are subroutine calls, not back
182        references. PCRE supports relative numbers with this syntax (I don't think
183        Oniguruma does).
185    12. Previously, a group with a zero repeat such as (...){0} was completely
186        omitted from the compiled regex. However, this means that if the group
187        was called as a subroutine from elsewhere in the pattern, things went wrong
188        (an internal error was given). Such groups are now left in the compiled
189        pattern, with a new opcode that causes them to be skipped at execution
190        time.
192    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
193        to the way PCRE behaves:
195        (a) A lone ] character is dis-allowed (Perl treats it as data).
197        (b) A back reference to an unmatched subpattern matches an empty string
198            (Perl fails the current match path).
200        (c) A data ] in a character class must be notated as \] because if the
201            first data character in a class is ], it defines an empty class. (In
202            Perl it is not possible to have an empty class.) The empty class []
203            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
204            The negative empty class [^] matches any one character, independently
205            of the DOTALL setting.
207    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
208        non-existent subpattern following a character class starting with ']' and
209        containing () gave an internal compiling error instead of "reference to
210        non-existent subpattern". Fortunately, when the pattern did exist, the
211        compiled code was correct. (When scanning forwards to check for the
212        existencd of the subpattern, it was treating the data ']' as terminating
213        the class, so got the count wrong. When actually compiling, the reference
214        was subsequently set up correctly.)
216    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
217        it was being rejected as not supported by pcre_dfa_exec(), even though
218        other assertions are supported. I have made pcre_dfa_exec() support
219        (*FAIL).
221    16. The implementation of 13c above involved the invention of a new opcode,
222        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
223        cannot be changed at match time, I realized I could make a small
224        improvement to matching performance by compiling OP_ALLANY instead of
225        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
226        on the OP_ANY path.
228    17. Compiling pcretest on Windows with readline support failed without the
229        following two fixes: (1) Make the unistd.h include conditional on
230        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
232    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
233        ncurses library to be included for pcretest when ReadLine support is
234        requested, but also to allow for it to be overridden. This patch came from
235        Daniel Bergström.
237    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
238        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
239        any errors with the current Unicode tables. Thanks to Peter Kankowski for
240        spotting this.
243    Version 7.6 28-Jan-08
244    ---------------------
246    1.  A character class containing a very large number of characters with
247        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
248        overflow.
250    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
251        HAVE_LONG_LONG is not defined.
253    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
254        bring them up to date and include new features. This patch includes:
256        - Fixed PH's badly added libz and libbz2 support.
257        - Fixed a problem with static linking.
258        - Added pcredemo. [But later removed - see 7 below.]
259        - Fixed dftables problem and added an option.
260        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
261            HAVE_LONG_LONG.
262        - Added readline support for pcretest.
263        - Added an listing of the option settings after cmake has run.
265    4.  A user submitted a patch to Makefile that makes it easy to create
266        "pcre.dll" under mingw when using Configure/Make. I added stuff to
267        Makefile.am that cause it to include this special target, without
268        affecting anything else. Note that the same mingw target plus all
269        the other distribution libraries and programs are now supported
270        when configuring with CMake (see 6 below) instead of with
271        Configure/Make.
273    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
274        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
275        exported in the Windows port". It has not yet been confirmed that the patch
276        solves the problem, but it does no harm.
278    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
279        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
280        with CMake, and also correct the comment about stack recursion.
282    7.  Remove the automatic building of pcredemo from the ./configure system and
283        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
284        of a program that users should build themselves after PCRE is installed, so
285        building it automatically is not really right. What is more, it gave
286        trouble in some build environments.
288    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
291    Version 7.5 10-Jan-08
292    ---------------------
294    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
295        values in parens when parsing an RE using the C++ wrapper."
297    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
298        Characters greater than 255 were excluded from the class instead of being
299        included.
301    3.  The same bug as (2) above applied to negated POSIX classes such as
302        [:^space:].
304    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
305        defined or documented. It seems to have been a typo for PCRE_STATIC, so
306        I have changed it.
308    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
309        first named subpattern) and a construct such as (?&a) would reference the
310        first named subpattern whose name started with "a" (in other words, the
311        length check was missing). Both these problems are fixed. "Subpattern name
312        expected" is now given for (?&) (a zero-length name), and this patch also
313        makes it give the same error for \k'' (previously it complained that that
314        was a reference to a non-existent subpattern).
316    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
317        this is right because (?- can be followed by option settings as well as by
318        digits. I have, however, made the messages clearer.
320    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
321        than the number used in the conditional) now cause a compile-time error.
322        This is actually not compatible with Perl, which accepts such patterns, but
323        treats the conditional as always being FALSE (as PCRE used to), but it
324        seems to me that giving a diagnostic is better.
326    8.  Change "alphameric" to the more common word "alphanumeric" in comments
327        and messages.
329    9.  Fix two occurrences of "backslash" in comments that should have been
330        "backspace".
332    10. Remove two redundant lines of code that can never be obeyed (their function
333        was moved elsewhere).
335    11. The program that makes PCRE's Unicode character property table had a bug
336        which caused it to generate incorrect table entries for sequences of
337        characters that have the same character type, but are in different scripts.
338        It amalgamated them into a single range, with the script of the first of
339        them. In other words, some characters were in the wrong script. There were
340        thirteen such cases, affecting characters in the following ranges:
342          U+002b0 - U+002c1
343          U+0060c - U+0060d
344          U+0061e - U+00612
345          U+0064b - U+0065e
346          U+0074d - U+0076d
347          U+01800 - U+01805
348          U+01d00 - U+01d77
349          U+01d9b - U+01dbf
350          U+0200b - U+0200f
351          U+030fc - U+030fe
352          U+03260 - U+0327f
353          U+0fb46 - U+0fbb1
354          U+10450 - U+1049d
356    12. The -o option (show only the matching part of a line) for pcregrep was not
357        compatible with GNU grep in that, if there was more than one match in a
358        line, it showed only the first of them. It now behaves in the same way as
359        GNU grep.
361    13. If the -o and -v options were combined for pcregrep, it printed a blank
362        line for every non-matching line. GNU grep prints nothing, and pcregrep now
363        does the same. The return code can be used to tell if there were any
364        non-matching lines.
366    14. Added --file-offsets and --line-offsets to pcregrep.
368    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
369        infinitely looping recursion. The bug was that positive lookaheads were not
370        being skipped when checking for a possible empty match (negative lookaheads
371        and both kinds of lookbehind were skipped).
373    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
374        inclusion of <windows.h> to before rather than after the definition of
375        INVALID_FILE_ATTRIBUTES (patch from David Byron).
377    17. Specifying a possessive quantifier with a specific limit for a Unicode
378        character property caused pcre_compile() to compile bad code, which led at
379        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
380        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
381        caused the error; without that there was no problem.
383    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
385    19. Added --enable-pcretest-libreadline.
387    20. In pcrecpp.cc, the variable 'count' was incremented twice in
388        RE::GlobalReplace(). As a result, the number of replacements returned was
389        double what it should be. I removed one of the increments, but Craig sent a
390        later patch that removed the other one (the right fix) and added unit tests
391        that check the return values (which was not done before).
393    21. Several CMake things:
395        (1) Arranged that, when cmake is used on Unix, the libraries end up with
396            the names libpcre and libpcreposix, not just pcre and pcreposix.
398        (2) The above change means that pcretest and pcregrep are now correctly
399            linked with the newly-built libraries, not previously installed ones.
403    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
404        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
405        UTF-8 newline character). The key issue is that the pattern starts .*;
406        this means that the match must be either at the beginning, or after a
407        newline. The bug was in the code for advancing after a failed match and
408        checking that the new position followed a newline. It was not taking
409        account of UTF-8 characters correctly.
411    23. PCRE was behaving differently from Perl in the way it recognized POSIX
412        character classes. PCRE was not treating the sequence [:...:] as a
413        character class unless the ... were all letters. Perl, however, seems to
414        allow any characters between [: and :], though of course it rejects as
415        unknown any "names" that contain non-letters, because all the known class
416        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
417        for example, whereas PCRE did not - it did not recognize a POSIX character
418        class. This seemed a bit dangerous, so the code has been changed to be
419        closer to Perl. The behaviour is not identical to Perl, because PCRE will
420        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
421        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
422        Perl does, and where it didn't before.
424    24. Rewrite so as to remove the single use of %n from pcregrep because in some
425        Windows environments %n is disabled by default.
428    Version 7.4 21-Sep-07
429    ---------------------
431    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
432        means that a class such as [\s] counted as "explicit reference to CR or
433        LF". That isn't really right - the whole point of the change was to try to
434        help when there was an actual mention of one of the two characters. So now
435        the change happens only if \r or \n (or a literal CR or LF) character is
436        encountered.
438    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
439        of both had grown to the point where there were only 3 bits left.
440        Fortunately, there was spare space in the data structure, and so I have
441        moved the internal flags into a new 16-bit field to free up more option
442        bits.
444    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
445        but did not set the internal JCHANGED flag - either of these is enough to
446        control the way the "get" function works - but the PCRE_INFO_JCHANGED
447        facility is supposed to tell if (?J) was ever used, so now (?J) at the
448        start sets both bits.
450    4.  Added options (at build time, compile time, exec time) to change \R from
451        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
453    5.  doc/pcresyntax.html was missing from the distribution.
455    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
456        compatibility, even though it is no longer used.
458    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
459        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
460        windows.h file is present (where different names are used). [This was
461        reversed later after testing - see 16 below.]
463    8.  Changed all #include <config.h> to #include "config.h". There were also
464        some further <pcre.h> cases that I changed to "pcre.h".
466    9.  When pcregrep was used with the --colour option, it missed the line ending
467        sequence off the lines that it output.
469    10. It was pointed out to me that arrays of string pointers cause lots of
470        relocations when a shared library is dynamically loaded. A technique of
471        using a single long string with a table of offsets can drastically reduce
472        these. I have refactored PCRE in four places to do this. The result is
473        dramatic:
475          Originally:                          290
476          After changing UCP table:            187
477          After changing error message table:   43
478          After changing table of "verbs"       36
479          After changing table of Posix names   22
481        Thanks to the folks working on Gregex for glib for this insight.
483    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
484        unicode-properties was also set.
486    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
488    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
489        checked only for CRLF.
491    14. Added casts to pcretest.c to avoid compiler warnings.
493    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
495    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
496        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
497        entirely. This removes changes made in 7 above.
499    17. The CMake files have been updated, and there is now more information about
500        building with CMake in the NON-UNIX-USE document.
503    Version 7.3 28-Aug-07
504    ---------------------
506     1. In the rejigging of the build system that eventually resulted in 7.1, the
507        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
508        brackets there is not right, since it causes compilers to look for an
509        installed pcre.h, not the version that is in the source that is being
510        compiled (which of course may be different). I have changed it back to:
512          #include "pcre.h"
514        I have a vague recollection that the change was concerned with compiling in
515        different directories, but in the new build system, that is taken care of
516        by the VPATH setting the Makefile.
518     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
519        when the subject happened to end in the byte 0x85 (e.g. if the last
520        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
521        characters but of course it shouldn't be taken as a newline when it is part
522        of another character. The bug was that, for an unlimited repeat of . in
523        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
524        characters when looking for a newline.
526     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
528     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
529        in debug output.
531     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
532        long printing in the pcrecpp unittest when running under MinGW.
534     6. ESC_K was left out of the EBCDIC table.
536     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
537        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
538        limit also applies to "virtual nesting" when a pattern is recursive, and in
539        this case 1000 isn't so big. I have been able to remove this limit at the
540        expense of backing off one optimization in certain circumstances. Normally,
541        when pcre_exec() would call its internal match() function recursively and
542        immediately return the result unconditionally, it uses a "tail recursion"
543        feature to save stack. However, when a subpattern that can match an empty
544        string has an unlimited repetition quantifier, it no longer makes this
545        optimization. That gives it a stack frame in which to save the data for
546        checking that an empty string has been matched. Previously this was taken
547        from the 1000-entry workspace that had been reserved. So now there is no
548        explicit limit, but more stack is used.
550     8. Applied Daniel's patches to solve problems with the import/export magic
551        syntax that is required for Windows, and which was going wrong for the
552        pcreposix and pcrecpp parts of the library. These were overlooked when this
553        problem was solved for the main library.
555     9. There were some crude static tests to avoid integer overflow when computing
556        the size of patterns that contain repeated groups with explicit upper
557        limits. As the maximum quantifier is 65535, the maximum group length was
558        set at 30,000 so that the product of these two numbers did not overflow a
559        32-bit integer. However, it turns out that people want to use groups that
560        are longer than 30,000 bytes (though not repeat them that many times).
561        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
562        made it possible to implement the integer overflow checks in a much more
563        dynamic way, which I have now done. The artificial limitation on group
564        length has been removed - we now have only the limit on the total length of
565        the compiled pattern, which depends on the LINK_SIZE setting.
567    10. Fixed a bug in the documentation for get/copy named substring when
568        duplicate names are permitted. If none of the named substrings are set, the
569        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
570        empty string.
572    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
573        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
574        because the ] is interpreted as the first data character and the
575        terminating ] is not found. PCRE has been made compatible with Perl in this
576        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
577        cause memory overwriting.
579    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
580        string has been matched (to stop an infinite loop). It was not recognizing
581        a conditional subpattern that could match an empty string if that
582        subpattern was within another subpattern. For example, it looped when
583        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
584        condition was not nested. This bug has been fixed.
586    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
587        past the start of the subject in the presence of bytes with the top bit
588        set, for example "\x8aBCD".
590    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
591        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
593    14. Optimized (?!) to (*FAIL).
595    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
596        This restricts code points to be within the range 0 to 0x10FFFF, excluding
597        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
598        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
599        does: it's just the validity check that is more restrictive.
601    16. Inserted checks for integer overflows during escape sequence (backslash)
602        processing, and also fixed erroneous offset values for syntax errors during
603        backslash processing.
605    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
606        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
608    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
609        caused an overrun.
611    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
612        something other than just ASCII characters) inside a group that had an
613        unlimited repeat caused a loop at compile time (while checking to see
614        whether the group could match an empty string).
616    20. Debugging a pattern containing \p or \P could cause a crash. For example,
617        [\P{Any}] did so. (Error in the code for printing property names.)
619    21. An orphan \E inside a character class could cause a crash.
621    22. A repeated capturing bracket such as (A)? could cause a wild memory
622        reference during compilation.
624    23. There are several functions in pcre_compile() that scan along a compiled
625        expression for various reasons (e.g. to see if it's fixed length for look
626        behind). There were bugs in these functions when a repeated \p or \P was
627        present in the pattern. These operators have additional parameters compared
628        with \d, etc, and these were not being taken into account when moving along
629        the compiled data. Specifically:
631        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
632            length.
634        (b) An item such as \pL+ within a repeated group could cause crashes or
635            loops.
637        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
638            "reference to non-existent subpattern" error.
640        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
642    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
643        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
645    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
647    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
648        character were causing crashes (broken optimization).
650    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
651        \p or \P) caused a compile-time loop.
653    28. More problems have arisen in unanchored patterns when CRLF is a valid line
654        break. For example, the unstudied pattern [\r\n]A does not match the string
655        "\r\nA" because change 7.0/46 below moves the current point on by two
656        characters after failing to match at the start. However, the pattern \nA
657        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
658        the same is true. There doesn't seem any very clean way out of this, but
659        what I have chosen to do makes the common cases work: PCRE now takes note
660        of whether there can be an explicit match for \r or \n anywhere in the
661        pattern, and if so, 7.0/46 no longer applies. As part of this change,
662        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
663        pattern has explicit CR or LF references.
665    29. Added (*CR) etc for changing newline setting at start of pattern.
668    Version 7.2 19-Jun-07
669    ---------------------
671     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
672        which is apparently normally available under Windows.
674     2. Re-jig the pcregrep tests with different newline settings in an attempt
675        to make them independent of the local environment's newline setting.
677     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
679     4. Some of the "internals" tests were previously cut out when the link size
680        was not 2, because the output contained actual offsets. The recent new
681        "Z" feature of pcretest means that these can be cut out, making the tests
682        usable with all link sizes.
684     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
685        stack recursion. This gives a massive performance boost under BSD, but just
686        a small improvement under Linux. However, it saves one field in the frame
687        in all cases.
689     6. Added more features from the forthcoming Perl 5.10:
691        (a) (?-n) (where n is a string of digits) is a relative subroutine or
692            recursion call. It refers to the nth most recently opened parentheses.
694        (b) (?+n) is also a relative subroutine call; it refers to the nth next
695            to be opened parentheses.
697        (c) Conditions that refer to capturing parentheses can be specified
698            relatively, for example, (?(-2)... or (?(+3)...
700        (d) \K resets the start of the current match so that everything before
701            is not part of it.
703        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
705        (f) \g{name} is another synonym - part of Perl 5.10's unification of
706            reference syntax.
708        (g) (?| introduces a group in which the numbering of parentheses in each
709            alternative starts with the same number.
711        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
713     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
716     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
717        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
718        for detecting groups that can match an empty string.
720     9. A pattern with a very large number of alternatives (more than several
721        hundred) was running out of internal workspace during the pre-compile
722        phase, where pcre_compile() figures out how much memory will be needed. A
723        bit of new cunning has reduced the workspace needed for groups with
724        alternatives. The 1000-alternative test pattern now uses 12 bytes of
725        workspace instead of running out of the 4096 that are available.
727    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
729    11. Applied patch from Google to remove an optimization that didn't quite work.
730        The report of the bug said:
732          pcrecpp::RE("a*").FullMatch("aaa") matches, while
733          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
734          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
736    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
737        it matched the wrong number of bytes.
740    Version 7.1 24-Apr-07
741    ---------------------
743     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
744        that is more "standard", making use of automake and other Autotools. There
745        is some re-arrangement of the files and adjustment of comments consequent
746        on this.
748     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
749        for recursive directory scanning broke on some systems because the files
750        are not scanned in any specific order and on different systems the order
751        was different. A call to "sort" has been inserted into RunGrepTest for the
752        approprate test as a short-term fix. In the longer term there may be an
753        alternative.
755     3. I had an email from Eric Raymond about problems translating some of PCRE's
756        man pages to HTML (despite the fact that I distribute HTML pages, some
757        people do their own conversions for various reasons). The problems
758        concerned the use of low-level troff macros .br and .in. I have therefore
759        removed all such uses from the man pages (some were redundant, some could
760        be replaced by .nf/.fi pairs). The 132html script that I use to generate
761        HTML has been updated to handle .nf/.fi and to complain if it encounters
762        .br or .in.
764     4. Updated comments in configure.ac that get placed in config.h.in and also
765        arranged for config.h to be included in the distribution, with the name
766        config.h.generic, for the benefit of those who have to compile without
767        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
769     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
770        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
771        makevp.bat for the current PCRE, using the additional files
772        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
774     6. A Windows user reported a minor discrepancy with test 2, which turned out
775        to be caused by a trailing space on an input line that had got lost in his
776        copy. The trailing space was an accident, so I've just removed it.
778     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
779        that is needed.
781     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
782        as "const" (a) because they are and (b) because it helps the PHP
783        maintainers who have recently made a script to detect big data structures
784        in the php code that should be moved to the .rodata section. I remembered
785        to update Builducptable as well, so it won't revert if ucptable.h is ever
786        re-created.
788     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
789        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
790        order to be able to cut out the UTF-8 tables in the latter when UTF-8
791        support is not required. This saves 1.5-2K of code, which is important in
792        some applications.
794        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
795        so as not to refer to the tables, even though these functions will never be
796        called when UTF-8 support is disabled. Otherwise there are problems with a
797        shared library.
799    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
801        (a) It was defining its arguments as char * instead of void *.
803        (b) It was assuming that all moves were upwards in memory; this was true
804            a long time ago when I wrote it, but is no longer the case.
806        The emulated memove() is provided for those environments that have neither
807        memmove() nor bcopy(). I didn't think anyone used it these days, but that
808        is clearly not the case, as these two bugs were recently reported.
810    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
811        and Detrail to create the HTML documentation, the .txt form of the man
812        pages, and it removes trailing spaces from listed files. It also creates
813        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
814        case, it wraps all the #defines with #ifndefs. This script should be run
815        before "make dist".
817    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
818        with Unicode property support.
820        (a) For a maximizing quantifier, if the two different cases of the
821            character were of different lengths in their UTF-8 codings (there are
822            some cases like this - I found 11), and the matching function had to
823            back up over a mixture of the two cases, it incorrectly assumed they
824            were both the same length.
826        (b) When PCRE was configured to use the heap rather than the stack for
827            recursion during matching, it was not correctly preserving the data for
828            the other case of a UTF-8 character when checking ahead for a match
829            while processing a minimizing repeat. If the check also involved
830            matching a wide character, but failed, corruption could cause an
831            erroneous result when trying to check for a repeat of the original
832            character.
834    13. Some tidying changes to the testing mechanism:
836        (a) The RunTest script now detects the internal link size and whether there
837            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
838            values substituted by "configure". (The RunGrepTest script already did
839            this for UTF-8.) The configure.ac script no longer substitutes the
840            relevant variables.
842        (b) The debugging options /B and /D in pcretest show the compiled bytecode
843            with length and offset values. This means that the output is different
844            for different internal link sizes. Test 2 is skipped for link sizes
845            other than 2 because of this, bypassing the problem. Unfortunately,
846            there was also a test in test 3 (the locale tests) that used /B and
847            failed for link sizes other than 2. Rather than cut the whole test out,
848            I have added a new /Z option to pcretest that replaces the length and
849            offset values with spaces. This is now used to make test 3 independent
850            of link size. (Test 2 will be tidied up later.)
852    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
853        segmentation fault instead of returning the appropriate error message.
855    15. In multiline mode when the newline sequence was set to "any", the pattern
856        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
857        This doesn't seem right; it now treats the CRLF combination as the line
858        ending, and so does not match in that case. It's only a pattern such as ^$
859        that would hit this one: something like ^ABC$ would have failed after \r
860        and then tried again after \r\n.
862    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
863        in an attempt to make files that differ only in their line terminators
864        compare equal. This works on Linux.
866    17. Under certain error circumstances pcregrep might try to free random memory
867        as it exited. This is now fixed, thanks to valgrind.
869    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
870        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
871        was because its rules for how to advance for /g after matching an empty
872        string at the end of a line did not allow for this case. They now check for
873        it specially.
875    20. pcretest is supposed to handle patterns and data of any length, by
876        extending its buffers when necessary. It was getting this wrong when the
877        buffer for a data line had to be extended.
879    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
880        CRLF as a newline sequence.
882    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
883        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
884        I have nevertheless tidied it up.
886    23. Added some casts to kill warnings from HP-UX ia64 compiler.
888    24. Added a man page for pcre-config.
891    Version 7.0 19-Dec-06
892    ---------------------
894     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
895        moving to gcc 4.1.1.
897     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
898        sys/time.h, which is documented as needed for this function. It doesn't
899        seem to matter on Linux, but it showed up on some releases of OS X.
901     3. It seems that there are systems where bytes whose values are greater than
902        127 match isprint() in the "C" locale. The "C" locale should be the
903        default when a C program starts up. In most systems, only ASCII printing
904        characters match isprint(). This difference caused the output from pcretest
905        to vary, making some of the tests fail. I have changed pcretest so that:
907        (a) When it is outputting text in the compiled version of a pattern, bytes
908            other than 32-126 are always shown as hex escapes.
910        (b) When it is outputting text that is a matched part of a subject string,
911            it does the same, unless a different locale has been set for the match
912            (using the /L modifier). In this case, it uses isprint() to decide.
914     4. Fixed a major bug that caused incorrect computation of the amount of memory
915        required for a compiled pattern when options that changed within the
916        pattern affected the logic of the preliminary scan that determines the
917        length. The relevant options are -x, and -i in UTF-8 mode. The result was
918        that the computed length was too small. The symptoms of this bug were
919        either the PCRE error "internal error: code overflow" from pcre_compile(),
920        or a glibc crash with a message such as "pcretest: free(): invalid next
921        size (fast)". Examples of patterns that provoked this bug (shown in
922        pcretest format) are:
924          /(?-x: )/x
925          /(?x)(?-x: \s*#\s*)/
926          /((?i)[\x{c0}])/8
927          /(?i:[\x{c0}])/8
929        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
930        is now done differently.
932     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
933        wrapper classes; (b) implement a new function in the C++ scanner that is
934        more efficient than the old way of doing things because it avoids levels of
935        recursion in the regex matching; (c) add a paragraph to the documentation
936        for the FullMatch() function.
938     6. The escape sequence \n was being treated as whatever was defined as
939        "newline". Not only was this contrary to the documentation, which states
940        that \n is character 10 (hex 0A), but it also went horribly wrong when
941        "newline" was defined as CRLF. This has been fixed.
943     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
944        was being set to -1 for the "end of line" case (supposedly a value that no
945        character can have). Though this value is never used (the check for end of
946        line is "zero bytes in current character"), it caused compiler complaints.
947        I've changed it to 0xffffffff.
949     8. In pcre_version.c, the version string was being built by a sequence of
950        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
951        string (as it is for production releases) called a macro with an empty
952        argument. The C standard says the result of this is undefined. The gcc
953        compiler treats it as an empty string (which was what was wanted) but it is
954        reported that Visual C gives an error. The source has been hacked around to
955        avoid this problem.
957     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
958        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
959        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
960        of them did).
962    10. Originally, pcretest opened its input and output without "b"; then I was
963        told that "b" was needed in some environments, so it was added for release
964        5.0 to both the input and output. (It makes no difference on Unix-like
965        systems.) Later I was told that it is wrong for the input on Windows. I've
966        now abstracted the modes into two macros, to make it easier to fiddle with
967        them, and removed "b" from the input mode under Windows.
969    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
971    12. Added -help and --help to pcretest as an official way of being reminded
972        of the options.
974    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
975        and pcrecpp.cc because they annoy compilers at high warning levels.
977    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
979    15. Fixed an occurrence of == in configure.ac that should have been = (shell
980        scripts are not C programs :-) and which was not noticed because it works
981        on Linux.
983    16. pcretest is supposed to handle any length of pattern and data line (as one
984        line or as a continued sequence of lines) by extending its input buffer if
985        necessary. This feature was broken for very long pattern lines, leading to
986        a string of junk being passed to pcre_compile() if the pattern was longer
987        than about 50K.
989    17. I have done a major re-factoring of the way pcre_compile() computes the
990        amount of memory needed for a compiled pattern. Previously, there was code
991        that made a preliminary scan of the pattern in order to do this. That was
992        OK when PCRE was new, but as the facilities have expanded, it has become
993        harder and harder to keep it in step with the real compile phase, and there
994        have been a number of bugs (see for example, 4 above). I have now found a
995        cunning way of running the real compile function in a "fake" mode that
996        enables it to compute how much memory it would need, while actually only
997        ever using a few hundred bytes of working memory and without too many
998        tests of the mode. This should make future maintenance and development
999        easier. A side effect of this work is that the limit of 200 on the nesting
1000        depth of parentheses has been removed (though this was never a serious
1001        limitation, I suspect). However, there is a downside: pcre_compile() now
1002        runs more slowly than before (30% or more, depending on the pattern). I
1003        hope this isn't a big issue. There is no effect on runtime performance.
1005    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
1006        newline (only possible for the last line of a file) and it was a
1007        pattern that set a locale (followed by /Lsomething), pcretest crashed.
1009    19. Added additional timing features to pcretest. (1) The -tm option now times
1010        matching only, not compiling. (2) Both -t and -tm can be followed, as a
1011        separate command line item, by a number that specifies the number of
1012        repeats to use when timing. The default is 50000; this gives better
1013        precision, but takes uncomfortably long for very large patterns.
1015    20. Extended pcre_study() to be more clever in cases where a branch of a
1016        subpattern has no definite first character. For example, (a*|b*)[cd] would
1017        previously give no result from pcre_study(). Now it recognizes that the
1018        first character must be a, b, c, or d.
1020    21. There was an incorrect error "recursive call could loop indefinitely" if
1021        a subpattern (or the entire pattern) that was being tested for matching an
1022        empty string contained only one non-empty item after a nested subpattern.
1023        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
1024        incorrectly, because the \d was being skipped in the check.
1026    22. The pcretest program now has a new pattern option /B and a command line
1027        option -b, which is equivalent to adding /B to every pattern. This causes
1028        it to show the compiled bytecode, without the additional information that
1029        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
1030        is the same as /B/I).
1032    23. A new optimization is now able automatically to treat some sequences such
1033        as a*b as a*+b. More specifically, if something simple (such as a character
1034        or a simple class like \d) has an unlimited quantifier, and is followed by
1035        something that cannot possibly match the quantified thing, the quantifier
1036        is automatically "possessified".
1038    24. A recursive reference to a subpattern whose number was greater than 39
1039        went wrong under certain circumstances in UTF-8 mode. This bug could also
1040        have affected the operation of pcre_study().
1042    25. Realized that a little bit of performance could be had by replacing
1043        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
1045    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
1047    27. Possessive quantifiers such as a++ were previously implemented by turning
1048        them into atomic groups such as ($>a+). Now they have their own opcodes,
1049        which improves performance. This includes the automatically created ones
1050        from 23 above.
1052    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
1053        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
1054        the first matched character to be a colon. This applied both to named and
1055        numbered groups.
1057    29. The ucpinternal.h header file was missing its idempotency #ifdef.
1059    30. I was sent a "project" file called libpcre.a.dev which I understand makes
1060        building PCRE on Windows easier, so I have included it in the distribution.
1062    31. There is now a check in pcretest against a ridiculously large number being
1063        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
1064        loop, the loop is abandoned.
1066    32. Forward references to subpatterns in conditions such as (?(2)...) where
1067        subpattern 2 is defined later cause pcre_compile() to search forwards in
1068        the pattern for the relevant set of parentheses. This search went wrong
1069        when there were unescaped parentheses in a character class, parentheses
1070        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
1072    33. "Subroutine" calls and backreferences were previously restricted to
1073        referencing subpatterns earlier in the regex. This restriction has now
1074        been removed.
1076    34. Added a number of extra features that are going to be in Perl 5.10. On the
1077        whole, these are just syntactic alternatives for features that PCRE had
1078        previously implemented using the Python syntax or my own invention. The
1079        other formats are all retained for compatibility.
1081        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
1082            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
1083            also .NET compatible.
1085        (b) A recursion or subroutine call to a named group can now be defined as
1086            (?&name) as well as (?P>name).
1088        (c) A backreference to a named group can now be defined as \k<name> or
1089            \k'name' as well as (?P=name). The new forms, as well as being in Perl
1090            5.10, are also .NET compatible.
1092        (d) A conditional reference to a named group can now use the syntax
1093            (?(<name>) or (?('name') as well as (?(name).
1095        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
1096            groups (named and numbered) that are never evaluated inline, but can be
1097            called as "subroutines" from elsewhere. In effect, the DEFINE condition
1098            is always false. There may be only one alternative in such a group.
1100        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
1101            as the simple (?(R). The condition is true only if the most recent
1102            recursion is that of the given number or name. It does not search out
1103            through the entire recursion stack.
1105        (g) The escape \gN or \g{N} has been added, where N is a positive or
1106            negative number, specifying an absolute or relative reference.
1108    35. Tidied to get rid of some further signed/unsigned compiler warnings and
1109        some "unreachable code" warnings.
1111    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
1112        things, this adds five new scripts.
1114    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
1115        There were also incompatibilities regarding the handling of \Q..\E inside
1116        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
1117        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
1119    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
1120        matches an empty string, and forcibly breaks the loop. There were bugs in
1121        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
1122        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
1123        separate and independent bugs (that affected different cases) have been
1124        fixed.
1126    39. Refactored the code to abolish the use of different opcodes for small
1127        capturing bracket numbers. This is a tidy that I avoided doing when I
1128        removed the limit on the number of capturing brackets for 3.5 back in 2001.
1129        The new approach is not only tidier, it makes it possible to reduce the
1130        memory needed to fix the previous bug (38).
1132    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
1133        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
1134        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
1135        mode.
1137    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
1138        report.
1140    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
1141        copy construction and assignment in the C++ wrapper.
1143    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
1144        couple of bugs that could have given wrong results in the "--newline=crlf"
1145        case.
1147    44. Added a number of casts and did some reorganization of signed/unsigned int
1148        variables following suggestions from Dair Grant. Also renamed the variable
1149        "this" as "item" because it is a C++ keyword.
1151    45. Arranged for dftables to add
1153          #include "pcre_internal.h"
1155        to pcre_chartables.c because without it, gcc 4.x may remove the array
1156        definition from the final binary if PCRE is built into a static library and
1157        dead code stripping is activated.
1159    46. For an unanchored pattern, if a match attempt fails at the start of a
1160        newline sequence, and the newline setting is CRLF or ANY, and the next two
1161        characters are CRLF, advance by two characters instead of one.
1164    Version 6.7 04-Jul-06
1165    ---------------------
1167     1. In order to handle tests when input lines are enormously long, pcretest has
1168        been re-factored so that it automatically extends its buffers when
1169        necessary. The code is crude, but this _is_ just a test program. The
1170        default size has been increased from 32K to 50K.
1172     2. The code in pcre_study() was using the value of the re argument before
1173        testing it for NULL. (Of course, in any sensible call of the function, it
1174        won't be NULL.)
1176     3. The memmove() emulation function in pcre_internal.h, which is used on
1177        systems that lack both memmove() and bcopy() - that is, hardly ever -
1178        was missing a "static" storage class specifier.
1180     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1181        containing an extended class (one that cannot be represented by a bitmap
1182        because it contains high-valued characters or Unicode property items, e.g.
1183        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1184        pattern, but PCRE should not loop if you do not (it no longer does).
1185        [Detail: two cases were found: (a) a repeated subpattern containing an
1186        extended class; (b) a recursive reference to a subpattern that followed a
1187        previous extended class. It wasn't skipping over the extended class
1188        correctly when UTF-8 mode was not set.]
1190     5. A negated single-character class was not being recognized as fixed-length
1191        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1192        compile error "lookbehind assertion is not fixed length".
1194     6. The RunPerlTest auxiliary script was showing an unexpected difference
1195        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1196        write a Perl script that can interpret lines of an input file either as
1197        byte characters or as UTF-8, which is what "perltest" was being required to
1198        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1199        can't do is switch easily at run time between having the "use utf8;" pragma
1200        or not. In the end, I fudged it by using the RunPerlTest script to insert
1201        "use utf8;" explicitly for the UTF-8 tests.
1203     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1204        the end of the subject string, contrary to the documentation and to what
1205        Perl does. This was true of both matching functions. Now it matches only at
1206        the start of the subject and immediately after *internal* newlines.
1208     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1209        a pointer to an int instead of a pointer to an unsigned long int. This
1210        caused problems on 64-bit systems.
1212     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1213        instance of the 'standard' template library not being so standard".
1215    10. There was no check on the number of named subpatterns nor the maximum
1216        length of a subpattern name. The product of these values is used to compute
1217        the size of the memory block for a compiled pattern. By supplying a very
1218        long subpattern name and a large number of named subpatterns, the size
1219        computation could be caused to overflow. This is now prevented by limiting
1220        the length of names to 32 characters, and the number of named subpatterns
1221        to 10,000.
1223    11. Subpatterns that are repeated with specific counts have to be replicated in
1224        the compiled pattern. The size of memory for this was computed from the
1225        length of the subpattern and the repeat count. The latter is limited to
1226        65535, but there was no limit on the former, meaning that integer overflow
1227        could in principle occur. The compiled length of a repeated subpattern is
1228        now limited to 30,000 bytes in order to prevent this.
1230    12. Added the optional facility to have named substrings with the same name.
1232    13. Added the ability to use a named substring as a condition, using the
1233        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1234        are numbers (not recommended). Forward references are permitted.
1236    14. Added forward references in named backreferences (if you see what I mean).
1238    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1239        pattern could run off the end of the subject. For example, the pattern
1240        "(?s)(.{1,5})"8 did this with the subject "ab".
1242    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1243        PCRE_CASELESS was set when matching characters that were quantified with ?
1244        or *.
1246    17. A character class other than a single negated character that had a minimum
1247        but no maximum quantifier - for example [ab]{6,} - was not handled
1248        correctly by pce_dfa_exec(). It would match only one character.
1250    18. A valid (though odd) pattern that looked like a POSIX character
1251        class but used an invalid character after [ (for example [[,abc,]]) caused
1252        pcre_compile() to give the error "Failed: internal error: code overflow" or
1253        in some cases to crash with a glibc free() error. This could even happen if
1254        the pattern terminated after [[ but there just happened to be a sequence of
1255        letters, a binary zero, and a closing ] in the memory that followed.
1257    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1258        over the years. Originally (before any Unicode support), just the bottom 8
1259        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1260        output from "man perlunicode" includes this:
1262          The regular expression compiler produces polymorphic opcodes.  That
1263          is, the pattern adapts to the data and automatically switches to
1264          the Unicode character scheme when presented with Unicode data--or
1265          instead uses a traditional byte scheme when presented with byte
1266          data.
1268        Sadly, a wide octal escape does not cause a switch, and in a string with
1269        no other multibyte characters, these octal escapes are treated as before.
1270        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1271        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1272        Unicode string.
1274        I have not perpetrated such confusion in PCRE. Up till now, it took just
1275        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1276        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1277        translate to the appropriate multibyte character.
1279    29. Applied some refactoring to reduce the number of warnings from Microsoft
1280        and Borland compilers. This has included removing the fudge introduced
1281        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1282        a warning about an unused variable.
1284    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1285        characters since release 4.0, because Perl (from release 5.004) does not.
1286        [Or at least, is documented not to: some releases seem to be in conflict
1287        with the documentation.] However, when a pattern was studied with
1288        pcre_study() and all its branches started with \s, PCRE still included VT
1289        as a possible starting character. Of course, this did no harm; it just
1290        caused an unnecessary match attempt.
1292    22. Removed a now-redundant internal flag bit that recorded the fact that case
1293        dependency changed within the pattern. This was once needed for "required
1294        byte" processing, but is no longer used. This recovers a now-scarce options
1295        bit. Also moved the least significant internal flag bit to the most-
1296        significant bit of the word, which was not previously used (hangover from
1297        the days when it was an int rather than a uint) to free up another bit for
1298        the future.
1300    23. Added support for CRLF line endings as well as CR and LF. As well as the
1301        default being selectable at build time, it can now be changed at runtime
1302        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1303        specify that it is scanning data with non-default line endings.
1305    24. Changed the definition of CXXLINK to make it agree with the definition of
1306        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1308    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1309        recursions. This makes a big different to stack usage for some patterns.
1311    26. If a subpattern containing a named recursion or subroutine reference such
1312        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1313        the space required for the compiled pattern went wrong and gave too small a
1314        value. Depending on the environment, this could lead to "Failed: internal
1315        error: code overflow at offset 49" or "glibc detected double free or
1316        corruption" errors.
1318    27. Applied patches from Google (a) to support the new newline modes and (b) to
1319        advance over multibyte UTF-8 characters in GlobalReplace.
1321    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1322        difference for some implementation of PCRE in some Windows version.
1324    29. Added some extra testing facilities to pcretest:
1326        \q<number>   in a data line sets the "match limit" value
1327        \Q<number>   in a data line sets the "match recursion limt" value
1328        -S <number>  sets the stack size, where <number> is in megabytes
1330        The -S option isn't available for Windows.
1333    Version 6.6 06-Feb-06
1334    ---------------------
1336     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1337        in pcreposix.h. I have copied the definition from pcre.h.
1339     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1340        because pcre.h is no longer a built file.
1342     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1343        not normally included in the compiled code.
1346    Version 6.5 01-Feb-06
1347    ---------------------
1349     1. When using the partial match feature with pcre_dfa_exec(), it was not
1350        anchoring the second and subsequent partial matches at the new starting
1351        point. This could lead to incorrect results. For example, with the pattern
1352        /1234/, partially matching against "123" and then "a4" gave a match.
1354     2. Changes to pcregrep:
1356        (a) All non-match returns from pcre_exec() were being treated as failures
1357            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1358            error message is output. Some extra information is given for the
1359            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1360            probably the only errors that are likely to be caused by users (by
1361            specifying a regex that has nested indefinite repeats, for instance).
1362            If there are more than 20 of these errors, pcregrep is abandoned.
1364        (b) A binary zero was treated as data while matching, but terminated the
1365            output line if it was written out. This has been fixed: binary zeroes
1366            are now no different to any other data bytes.
1368        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1369            used to set a locale for matching. The --locale=xxxx long option has
1370            been added (no short equivalent) to specify a locale explicitly on the
1371            pcregrep command, overriding the environment variables.
1373        (d) When -B was used with -n, some line numbers in the output were one less
1374            than they should have been.
1376        (e) Added the -o (--only-matching) option.
1378        (f) If -A or -C was used with -c (count only), some lines of context were
1379            accidentally printed for the final match.
1381        (g) Added the -H (--with-filename) option.
1383        (h) The combination of options -rh failed to suppress file names for files
1384            that were found from directory arguments.
1386        (i) Added the -D (--devices) and -d (--directories) options.
1388        (j) Added the -F (--fixed-strings) option.
1390        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1392        (l) Added the --colo(u)r option.
1394        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1395            is not present by default.
1397     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1398        items such as (?R) or (?1), when the recursion could match a number of
1399        alternatives. If it matched one of the alternatives, but subsequently,
1400        outside the recursion, there was a failure, the code tried to back up into
1401        the recursion. However, because of the way PCRE is implemented, this is not
1402        possible, and the result was an incorrect result from the match.
1404        In order to prevent this happening, the specification of recursion has
1405        been changed so that all such subpatterns are automatically treated as
1406        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1408     4. I had overlooked the fact that, in some locales, there are characters for
1409        which isalpha() is true but neither isupper() nor islower() are true. In
1410        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1411        and ordfeminine) are like this. This affected the treatment of \w and \W
1412        when they appeared in character classes, but not when they appeared outside
1413        a character class. The bit map for "word" characters is now created
1414        separately from the results of isalnum() instead of just taking it from the
1415        upper, lower, and digit maps. (Plus the underscore character, of course.)
1417     5. The above bug also affected the handling of POSIX character classes such as
1418        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1419        permanent tables. Instead, the bit maps for such a class were previously
1420        created as the appropriate unions of the upper, lower, and digit bitmaps.
1421        Now they are created by subtraction from the [[:word:]] class, which has
1422        its own bitmap.
1424     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1425        It is created by subtracting the vertical space characters (\x09, \x0a,
1426        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1427        subtraction was done in the overall bitmap for a character class, meaning
1428        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1429        be recognized. This bug has been fixed.
1431     7. Patches from the folks at Google:
1433          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1434          real life, but is still worth protecting against".
1436          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1437          regular expressions".
1439          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1440          have it.
1442          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1443          "configure" and the latter not, in order to fix a problem somebody had
1444          with compiling the Arg class on HP-UX.
1446          (e) Improve the error-handling of the C++ wrapper a little bit.
1448          (f) New tests for checking recursion limiting.
1450     8. The pcre_memmove() function, which is used only if the environment does not
1451        have a standard memmove() function (and is therefore rarely compiled),
1452        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1453        returning a result (though PCRE never actually uses the result).
1455     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1456        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1457        returned instead of calling malloc() with an overflowing number that would
1458        most likely cause subsequent chaos.
1460    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1462    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1463        with this option is matched, the nmatch and pmatch options of regexec() are
1464        ignored.
1466    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1467        provided in case anyone wants to the the POSIX interface with UTF-8
1468        strings.
1470    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1471        C++ linking (needed for some HP-UX environments).
1473    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1474        (unused parameter) and in the pcre_printint() function (omitted "default"
1475        switch label when the default is to do nothing).
1477    15. Added some code to make it possible, when PCRE is compiled as a C++
1478        library, to replace subject pointers for pcre_exec() with a smart pointer
1479        class, thus making it possible to process discontinuous strings.
1481    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1482        much the same function. They were added by different people who were trying
1483        to make PCRE easy to compile on non-Unix systems. It has been suggested
1484        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1485        for compiling on Windows systems. I have therefore replaced it with
1486        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1487        defaults to "extern" for C or "extern C" for C++, which works fine on
1488        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1489        SCOPE with something explicit in config.h. In addition:
1491        (a) pcreposix.h still had just "extern" instead of either of these macros;
1492            I have replaced it with PCRE_DATA_SCOPE.
1494        (b) Functions such as _pcre_xclass(), which are internal to the library,
1495            but external in the C sense, all had PCRE_EXPORT in their definitions.
1496            This is apparently wrong for the Windows case, so I have removed it.
1497            (It makes no difference on Unix-like systems.)
1499    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1500        of recursive calls to match(). This is different to MATCH_LIMIT because
1501        that limits the total number of calls to match(), not all of which increase
1502        the depth of recursion. Limiting the recursion depth limits the amount of
1503        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1504        when PCRE is compiled, and changed at run time. A patch from Google adds
1505        this functionality to the C++ interface.
1507    18. Changes to the handling of Unicode character properties:
1509        (a) Updated the table to Unicode 4.1.0.
1511        (b) Recognize characters that are not in the table as "Cn" (undefined).
1513        (c) I revised the way the table is implemented to a much improved format
1514            which includes recognition of ranges. It now supports the ranges that
1515            are defined in UnicodeData.txt, and it also amalgamates other
1516            characters into ranges. This has reduced the number of entries in the
1517            table from around 16,000 to around 3,000, thus reducing its size
1518            considerably. I realized I did not need to use a tree structure after
1519            all - a binary chop search is just as efficient. Having reduced the
1520            number of entries, I extended their size from 6 bytes to 8 bytes to
1521            allow for more data.
1523        (d) Added support for Unicode script names via properties such as \p{Han}.
1525    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1526        matching that character.
1528    20. When matching a repeated Unicode property with a minimum greater than zero,
1529        (for example \pL{2,}), PCRE could look past the end of the subject if it
1530        reached it while seeking the minimum number of characters. This could
1531        happen only if some of the characters were more than one byte long, because
1532        there is a check for at least the minimum number of bytes.
1534    21. Refactored the implementation of \p and \P so as to be more general, to
1535        allow for more different types of property in future. This has changed the
1536        compiled form incompatibly. Anybody with saved compiled patterns that use
1537        \p or \P will have to recompile them.
1539    22. Added "Any" and "L&" to the supported property types.
1541    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1542        but give a compile time error if the value is greater than 0xff.
1544    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1545        accidentally not being installed or uninstalled.
1547    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1548        made were to insert the current release number. This seemed silly, because
1549        it made things harder for people building PCRE on systems that don't run
1550        "configure". I have turned pcre.h into a distributed file, no longer built
1551        by "configure", with the version identification directly included. There is
1552        no longer a pcre.h.in file.
1554        However, this change necessitated a change to the pcre-config script as
1555        well. It is built from pcre-config.in, and one of the substitutions was the
1556        release number. I have updated configure.ac so that ./configure now finds
1557        the release number by grepping pcre.h.
1559    26. Added the ability to run the tests under valgrind.
1562    Version 6.4 05-Sep-05
1563    ---------------------
1565     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1566        "--" to be printed when multiple files were scanned, even when none of the
1567        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1568        consider it to be a bug, and have restored the previous behaviour.
1570     2. A couple of code tidies to get rid of compiler warnings.
1572     3. The pcretest program used to cheat by referring to symbols in the library
1573        whose names begin with _pcre_. These are internal symbols that are not
1574        really supposed to be visible externally, and in some environments it is
1575        possible to suppress them. The cheating is now confined to including
1576        certain files from the library's source, which is a bit cleaner.
1578     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1579        file's purpose clearer.
1581     5. Reorganized pcre_ucp_findchar().
1584    Version 6.3 15-Aug-05
1585    ---------------------
1587     1. The file libpcre.pc.in did not have general read permission in the tarball.
1589     2. There were some problems when building without C++ support:
1591        (a) If C++ support was not built, "make install" and "make test" still
1592            tried to test it.
1594        (b) There were problems when the value of CXX was explicitly set. Some
1595            changes have been made to try to fix these, and ...
1597        (c) --disable-cpp can now be used to explicitly disable C++ support.
1599        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1600            backslash in a target when C++ was disabled. This confuses some
1601            versions of "make", apparently. Using an intermediate variable solves
1602            this. (Same for CPP_LOBJ.)
1604     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1605        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1606        necessary on certain architectures.
1608     4. Added a setting of -export-symbols-regex to the link command to remove
1609        those symbols that are exported in the C sense, but actually are local
1610        within the library, and not documented. Their names all begin with
1611        "_pcre_". This is not a perfect job, because (a) we have to except some
1612        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1613        available (and never for static libraries). I have made a note to try to
1614        find a way round (a) in the future.
1617    Version 6.2 01-Aug-05
1618    ---------------------
1620     1. There was no test for integer overflow of quantifier values. A construction
1621        such as {1111111111111111} would give undefined results. What is worse, if
1622        a minimum quantifier for a parenthesized subpattern overflowed and became
1623        negative, the calculation of the memory size went wrong. This could have
1624        led to memory overwriting.
1626     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1628     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1629        operating environments where this matters.
1631     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1632        PCRE options from within the C++ wrapper.
1634     5. Named capturing subpatterns were not being correctly counted when a pattern
1635        was compiled. This caused two problems: (a) If there were more than 100
1636        such subpatterns, the calculation of the memory needed for the whole
1637        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1638        back references of the form \12, where the number was greater than 9, were
1639        not recognized as back references, even though there were sufficient
1640        previous subpatterns.
1642     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1643        versions of gcc, e.g. 2.95.4.
1646    Version 6.1 21-Jun-05
1647    ---------------------
1649     1. There was one reference to the variable "posix" in pcretest.c that was not
1650        surrounded by "#if !defined NOPOSIX".
1652     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1653        the cross-check on the old pcre_info() function, for the benefit of the
1654        cut-down version of PCRE that is currently imported into Exim.
1656     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1657        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1658        patterns that start (?i) but I don't think that matters. The use of (?i) is
1659        just an example; this all applies to the other options as well.
1661     4. Since libtool seems to echo the compile commands it is issuing, the output
1662        from "make" can be reduced a bit by putting "@" in front of each libtool
1663        compile command.
1665     5. Patch from the folks at Google for configure.in to be a bit more thorough
1666        in checking for a suitable C++ installation before trying to compile the
1667        C++ stuff. This should fix a reported problem when a compiler was present,
1668        but no suitable headers.
1670     6. The man pages all had just "PCRE" as their title. I have changed them to
1671        be the relevant file name. I have also arranged that these names are
1672        retained in the file doc/pcre.txt, which is a concatenation in text format
1673        of all the man pages except the little individual ones for each function.
1675     7. The NON-UNIX-USE file had not been updated for the different set of source
1676        files that come with release 6. I also added a few comments about the C++
1677        wrapper.
1680    Version 6.0 07-Jun-05
1681    ---------------------
1683     1. Some minor internal re-organization to help with my DFA experiments.
1685     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1686        didn't matter for the library itself when fully configured, but did matter
1687        when compiling without UCP support, or within Exim, where the ucp files are
1688        not imported.
1690     3. Refactoring of the library code to split up the various functions into
1691        different source modules. The addition of the new DFA matching code (see
1692        below) to a single monolithic source would have made it really too
1693        unwieldy, quite apart from causing all the code to be include in a
1694        statically linked application, when only some functions are used. This is
1695        relevant even without the DFA addition now that patterns can be compiled in
1696        one application and matched in another.
1698        The downside of splitting up is that there have to be some external
1699        functions and data tables that are used internally in different modules of
1700        the library but which are not part of the API. These have all had their
1701        names changed to start with "_pcre_" so that they are unlikely to clash
1702        with other external names.
1704     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1705        a different (DFA) algorithm. Although it is slower than the original
1706        function, it does have some advantages for certain types of matching
1707        problem.
1709     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1710        including restarting after a partial match.
1712     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1713        defined when compiling for Windows was sent to me. I have put it into the
1714        code, though I have no means of testing or verifying it.
1716     7. Added the pcre_refcount() auxiliary function.
1718     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1719        match before or at the first newline in the subject string. In pcretest,
1720        the /f option on a pattern can be used to set this.
1722     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1723        would behave wrongly. This has been present in PCRE since release 4.0.
1725    10. A number of changes to the pcregrep command:
1727        (a) Refactored how -x works; insert ^(...)$ instead of setting
1728            PCRE_ANCHORED and checking the length, in preparation for adding
1729            something similar for -w.
1731        (b) Added the -w (match as a word) option.
1733        (c) Refactored the way lines are read and buffered so as to have more
1734            than one at a time available.
1736        (d) Implemented a pcregrep test script.
1738        (e) Added the -M (multiline match) option. This allows patterns to match
1739            over several lines of the subject. The buffering ensures that at least
1740            8K, or the rest of the document (whichever is the shorter) is available
1741            for matching (and similarly the previous 8K for lookbehind assertions).
1743        (f) Changed the --help output so that it now says
1745              -w, --word-regex(p)
1747            instead of two lines, one with "regex" and the other with "regexp"
1748            because that confused at least one person since the short forms are the
1749            same. (This required a bit of code, as the output is generated
1750            automatically from a table. It wasn't just a text change.)
1752        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1753            option but starts with a hyphen. Could be a pattern or a path name
1754            starting with a hyphen, for instance.
1756        (h) "-" can be given as a file name to represent stdin.
1758        (i) When file names are being printed, "(standard input)" is used for
1759            the standard input, for compatibility with GNU grep. Previously
1760            "<stdin>" was used.
1762        (j) The option --label=xxx can be used to supply a name to be used for
1763            stdin when file names are being printed. There is no short form.
1765        (k) Re-factored the options decoding logic because we are going to add
1766            two more options that take data. Such options can now be given in four
1767            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1769        (l) Added the -A, -B, and -C options for requesting that lines of context
1770            around matches be printed.
1772        (m) Added the -L option to print the names of files that do not contain
1773            any matching lines, that is, the complement of -l.
1775        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1776            continue to scan other files.
1778        (o) The -s option was incorrectly implemented. For compatibility with other
1779            greps, it now suppresses the error message for a non-existent or non-
1780            accessible file (but not the return code). There is a new option called
1781            -q that suppresses the output of matching lines, which was what -s was
1782            previously doing.
1784        (p) Added --include and --exclude options to specify files for inclusion
1785            and exclusion when recursing.
1787    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1788        Hopefully, it now does.
1790    12. Missing cast in pcre_study().
1792    13. Added an "uninstall" target to the makefile.
1794    14. Replaced "extern" in the function prototypes in Makefile.in with
1795        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1796        world, but is set differently for Windows.
1798    15. Added a second compiling function called pcre_compile2(). The only
1799        difference is that it has an extra argument, which is a pointer to an
1800        integer error code. When there is a compile-time failure, this is set
1801        non-zero, in addition to the error test pointer being set to point to an
1802        error message. The new argument may be NULL if no error number is required
1803        (but then you may as well call pcre_compile(), which is now just a
1804        wrapper). This facility is provided because some applications need a
1805        numeric error indication, but it has also enabled me to tidy up the way
1806        compile-time errors are handled in the POSIX wrapper.
1808    16. Added VPATH=.libs to the makefile; this should help when building with one
1809        prefix path and installing with another. (Or so I'm told by someone who
1810        knows more about this stuff than I do.)
1812    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1813        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1814        match everything, including newlines. This is not POSIX-compatible, but
1815        somebody wanted the feature. From pcretest it can be activated by using
1816        both the P and the s flags.
1818    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1820    19. libpcre.pc was being incorrectly installed as executable.
1822    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1823        it now also looks for '\r' so that it will work unmodified on Windows.
1825    21. Added Google's contributed C++ wrapper to the distribution.
1827    22. Added some untidy missing memory free() calls in pcretest, to keep
1828        Electric Fence happy when testing.
1832    Version 5.0 13-Sep-04
1833    ---------------------
1835     1. Internal change: literal characters are no longer packed up into items
1836        containing multiple characters in a single byte-string. Each character
1837        is now matched using a separate opcode. However, there may be more than one
1838        byte in the character in UTF-8 mode.
1840     2. The pcre_callout_block structure has two new fields: pattern_position and
1841        next_item_length. These contain the offset in the pattern to the next match
1842        item, and its length, respectively.
1844     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1845        insertion of callouts before each pattern item. Added the /C option to
1846        pcretest to make use of this.
1848     4. On the advice of a Windows user, the lines
1850          #if defined(_WIN32) || defined(WIN32)
1851          _setmode( _fileno( stdout ), 0x8000 );
1852          #endif  /* defined(_WIN32) || defined(WIN32) */
1854        have been added to the source of pcretest. This apparently does useful
1855        magic in relation to line terminators.
1857     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1858        for the benefit of those environments where the "b" makes a difference.
1860     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1861        to know about it. I have put a hack into configure.in that adds in code
1862        to set GCC=yes if CC=icc. This seems to end up at a point in the
1863        generated configure script that is early enough to affect the setting of
1864        compiler options, which is what is needed, but I have no means of testing
1865        whether it really works. (The user who reported this had patched the
1866        generated configure script, which of course I cannot do.)
1868        LATER: After change 22 below (new libtool files), the configure script
1869        seems to know about icc (and also ecc). Therefore, I have commented out
1870        this hack in configure.in.
1872     7. Added support for pkg-config (2 patches were sent in).
1874     8. Negated POSIX character classes that used a combination of internal tables
1875        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1876        [[:^ascii]]. Typically, they would match almost any characters. The other
1877        POSIX classes were not broken in this way.
1879     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1880        to find the match, as PCRE was deluded into thinking that the match had to
1881        start at the start point or following a newline. The same bug applied to
1882        patterns with negative forward assertions or any backward assertions
1883        preceding ".*" at the start, unless the pattern required a fixed first
1884        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1886    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1887        starting at the last subject character, bytes beyond the end of the subject
1888        string were read.
1890    11. Renamed the variable "class" as "classbits" to make life easier for C++
1891        users. (Previously there was a macro definition, but it apparently wasn't
1892        enough.)
1894    12. Added the new field "tables" to the extra data so that tables can be passed
1895        in at exec time, or the internal tables can be re-selected. This allows
1896        a compiled regex to be saved and re-used at a later time by a different
1897        program that might have everything at different addresses.
1899    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1900        -R library as well as a -L library.
1902    14. The debugging options of pcretest (-d on the command line or D on a
1903        pattern) showed incorrect output for anything following an extended class
1904        that contained multibyte characters and which was followed by a quantifier.
1906    15. Added optional support for general category Unicode character properties
1907        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1908        support. It adds about 90K to the size of the library. The meanings of the
1909        inbuilt class escapes such as \d and \s have NOT been changed.
1911    16. Updated pcredemo.c to include calls to free() to release the memory for the
1912        compiled pattern.
1914    17. The generated file chartables.c was being created in the source directory
1915        instead of in the building directory. This caused the build to fail if the
1916        source directory was different from the building directory, and was
1917        read-only.
1919    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1920        file. No doubt somebody will tell me if they don't make sense... Also added
1921        Dan Mooney's comments about building on OpenVMS.
1923    19. Added support for partial matching via the PCRE_PARTIAL option for
1924        pcre_exec() and the \P data escape in pcretest.
1926    20. Extended pcretest with 3 new pattern features:
1928        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1929              write the compiled pattern to the file whose name is "rest-of-line".
1930              This is a straight binary dump of the data, with the saved pointer to
1931              the character tables forced to be NULL. The study data, if any, is
1932              written too. After writing, pcretest reads a new pattern.
1934        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1935              compiled pattern from the given file. There must not be any
1936              occurrences of "<" in the file name (pretty unlikely); if there are,
1937              pcretest will instead treat the initial "<" as a pattern delimiter.
1938              After reading in the pattern, pcretest goes on to read data lines as
1939              usual.
1941        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1942              and 16-bit fields in a compiled pattern, to simulate a pattern that
1943              was compiled on a host of opposite endianness.
1945    21. The pcre-exec() function can now cope with patterns that were compiled on
1946        hosts of opposite endianness, with this restriction:
1948          As for any compiled expression that is saved and used later, the tables
1949          pointer field cannot be preserved; the extra_data field in the arguments
1950          to pcre_exec() should be used to pass in a tables address if a value
1951          other than the default internal tables were used at compile time.
1953    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1954        now diagnosed as an error. Previously, most of the time, a negative number
1955        would have been treated as zero, but if in addition "ovector" was passed as
1956        NULL, a crash could occur.
1958    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1959        new versions from the libtool 1.5 distribution (the last one is a copy of
1960        a file called libtool.m4). This seems to have fixed the need to patch
1961        "configure" to support Darwin 1.3 (which I used to do). However, I still
1962        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1963        workstation).
1965    24. Changed the PCRE licence to be the more standard "BSD" licence.
1968    Version 4.5 01-Dec-03
1969    ---------------------
1971     1. There has been some re-arrangement of the code for the match() function so
1972        that it can be compiled in a version that does not call itself recursively.
1973        Instead, it keeps those local variables that need separate instances for
1974        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1975        needs to "recurse". Keeping track of where control must go is done by means
1976        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1977        hide most of the details from the main code, and operates only if
1978        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1979        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1980        operating.
1982        To make it easier for callers to provide specially tailored get/free
1983        functions for this usage, two new functions, pcre_stack_malloc, and
1984        pcre_stack_free, are used. They are always called in strict stacking order,
1985        and the size of block requested is always the same.
1987        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1988        PCRE has been compiled to use the stack or the heap for recursion. The
1989        -C option of pcretest uses this to show which version is compiled.
1991        A new data escape \S, is added to pcretest; it causes the amounts of store
1992        obtained and freed by both kinds of malloc/free at match time to be added
1993        to the output.
1995     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1996        what's available on my current Linux desktop machine.
1998     3. When matching a UTF-8 string, the test for a valid string at the start has
1999        been extended. If start_offset is not zero, PCRE now checks that it points
2000        to a byte that is the start of a UTF-8 character. If not, it returns
2001        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
2002        this is necessary because there may be backward assertions in the pattern.
2003        When matching the same subject several times, it may save resources to use
2004        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
2006     4. The code for checking the validity of UTF-8 strings has been tightened so
2007        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
2008        containing "overlong sequences".
2010     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
2011        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
2012        should have been "&", but it just so happened that all the cases this let
2013        through by mistake were picked up later in the function.
2015     6. I had used a variable called "isblank" - this is a C99 function, causing
2016        some compilers to warn. To avoid this, I renamed it (as "blankclass").
2018     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
2019        prompting; (b) run "./pcretest /dev/null" at the start of the test script
2020        so the version is shown; (c) stop "make test" echoing "./RunTest".
2022     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
2024     9. The prototype for memmove() for systems that don't have it was using
2025        size_t, but the inclusion of the header that defines size_t was later. I've
2026        moved the #includes for the C headers earlier to avoid this.
2028    10. Added some adjustments to the code to make it easier to compiler on certain
2029        special systems:
2031          (a) Some "const" qualifiers were missing.
2032          (b) Added the macro EXPORT before all exported functions; by default this
2033              is defined to be empty.
2034          (c) Changed the dftables auxiliary program (that builds chartables.c) so
2035              that it reads its output file name as an argument instead of writing
2036              to the standard output and assuming this can be redirected.
2038    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
2039        class containing characters with values greater than 255, PCRE compilation
2040        went into a loop.
2042    12. A recursive reference to a subpattern that was within another subpattern
2043        that had a minimum quantifier of zero caused PCRE to crash. For example,
2044        (x(y(?2))z)? provoked this bug with a subject that got as far as the
2045        recursion. If the recursively-called subpattern itself had a zero repeat,
2046        that was OK.
2048    13. In pcretest, the buffer for reading a data line was set at 30K, but the
2049        buffer into which it was copied (for escape processing) was still set at
2050        1024, so long lines caused crashes.
2052    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
2053        "internal error: code overflow...". This applied to any character class
2054        that was followed by a possessive quantifier.
2056    15. Modified the Makefile to add libpcre.la as a prerequisite for
2057        libpcreposix.la because I was told this is needed for a parallel build to
2058        work.
2060    16. If a pattern that contained .* following optional items at the start was
2061        studied, the wrong optimizing data was generated, leading to matching
2062        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
2063        matching string must start with a or b or c. The correct conclusion for
2064        this pattern is that a match can start with any character.
2067    Version 4.4 13-Aug-03
2068    ---------------------
2070     1. In UTF-8 mode, a character class containing characters with values between
2071        127 and 255 was not handled correctly if the compiled pattern was studied.
2072        In fixing this, I have also improved the studying algorithm for such
2073        classes (slightly).
2075     2. Three internal functions had redundant arguments passed to them. Removal
2076        might give a very teeny performance improvement.
2078     3. Documentation bug: the value of the capture_top field in a callout is *one
2079        more than* the number of the hightest numbered captured substring.
2081     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
2082        in incorrectly linking with a previously installed version. They now link
2083        explicitly with libpcre.la.
2085     5. configure.in no longer needs to recognize Cygwin specially.
2087     6. A problem in pcre.in for Windows platforms is fixed.
2089     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
2090        pcretest, it used to include the size of the study block as part of its
2091        output. Unfortunately, the structure contains a field that has a different
2092        size on different hardware architectures. This meant that the tests that
2093        showed this size failed. As the block is currently always of a fixed size,
2094        this information isn't actually particularly useful in pcretest output, so
2095        I have just removed it.
2097     8. Three pre-processor statements accidentally did not start in column 1.
2098        Sadly, there are *still* compilers around that complain, even though
2099        standard C has not required this for well over a decade. Sigh.
2101     9. In pcretest, the code for checking callouts passed small integers in the
2102        callout_data field, which is a void * field. However, some picky compilers
2103        complained about the casts involved for this on 64-bit systems. Now
2104        pcretest passes the address of the small integer instead, which should get
2105        rid of the warnings.
2107    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
2108        both compile and run time, and gives an error if an invalid UTF-8 sequence
2109        is found. There is a option for disabling this check in cases where the
2110        string is known to be correct and/or the maximum performance is wanted.
2112    11. In response to a bug report, I changed one line in Makefile.in from
2114            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
2115        to
2116            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
2118        to look similar to other lines, but I have no way of telling whether this
2119        is the right thing to do, as I do not use Windows. No doubt I'll get told
2120        if it's wrong...
2123    Version 4.3 21-May-03
2124    ---------------------
2126    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
2127       Makefile.
2129    2. Some refactoring to improve the quality of the code:
2131       (i)   The utf8_table... variables are now declared "const".
2133       (ii)  The code for \cx, which used the "case flipping" table to upper case
2134             lower case letters, now just substracts 32. This is ASCII-specific,
2135             but the whole concept of \cx is ASCII-specific, so it seems
2136             reasonable.
2138       (iii) PCRE was using its character types table to recognize decimal and
2139             hexadecimal digits in the pattern. This is silly, because it handles
2140             only 0-9, a-f, and A-F, but the character types table is locale-
2141             specific, which means strange things might happen. A private
2142             table is now used for this - though it costs 256 bytes, a table is
2143             much faster than multiple explicit tests. Of course, the standard
2144             character types table is still used for matching digits in subject
2145             strings against \d.
2147       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
2148             ending in _t are). So I've renamed it as ESC_tee.
2150    3. The first argument for regexec() in the POSIX wrapper should have been
2151       defined as "const".
2153    4. Changed pcretest to use malloc() for its buffers so that they can be
2154       Electric Fenced for debugging.
2156    5. There were several places in the code where, in UTF-8 mode, PCRE would try
2157       to read one or more bytes before the start of the subject string. Often this
2158       had no effect on PCRE's behaviour, but in some circumstances it could
2159       provoke a segmentation fault.
2161    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
2162       to try to read one or more bytes before the start of the subject string.
2164    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
2165       UTF-8 support could misbehave in various ways if the subject string
2166       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
2167       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
2168       back over UTF-8 characters.)
2171    Version 4.2 14-Apr-03
2172    ---------------------
2174    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
2176    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
2177         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
2178         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
2179         [WIN_PREFIX]: new variable, "cyg" for Cygwin
2180         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
2181           and BUILD_EXEEXT
2182         Note: automatic setting of the BUILD variables is not yet working
2183         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
2184           compile-time but not at link-time
2185         [LINK]: use for linking executables only
2186         make different versions for Windows and non-Windows
2187         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
2188           libraries
2189         [LINK_FOR_BUILD]: new variable
2190         [OBJEXT]: use throughout
2191         [EXEEXT]: use throughout
2192         <winshared>: new target
2193         <wininstall>: new target
2194         <dftables.o>: use native compiler
2195         <dftables>: use native linker
2196         <install>: handle Windows platform correctly
2197         <clean>: ditto
2198         <check>: ditto
2199         copy DLL to top builddir before testing
2201       As part of these changes, -no-undefined was removed again. This was reported
2202       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
2203       in any case.
2205    3. Some tidies to get rid of compiler warnings:
2207       . In the match_data structure, match_limit was an unsigned long int, whereas
2208         match_call_count was an int. I've made them both unsigned long ints.
2210       . In pcretest the fact that a const uschar * doesn't automatically cast to
2211         a void * provoked a warning.
2213       . Turning on some more compiler warnings threw up some "shadow" variables
2214         and a few more missing casts.
2216    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
2217       option, a class that contained a single character with a value between 128
2218       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
2220    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
2221       option, a class that contained several characters, but with at least one
2222       whose value was between 128 and 255 caused PCRE to crash.
2225    Version 4.1 12-Mar-03
2226    ---------------------
2228    1. Compiling with gcc -pedantic found a couple of places where casts were
2229    needed, and a string in dftables.c that was longer than standard compilers are
2230    required to support.
2232    2. Compiling with Sun's compiler found a few more places where the code could
2233    be tidied up in order to avoid warnings.
2235    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
2236    first of these names is deprecated in the latest Autoconf in favour of the name
2237    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
2238    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
2239    analogy I have changed it to CFLAGS_FOR_BUILD.
2241    4. Added -no-undefined to the linking command in the Makefile, because this is
2242    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2243    linking step for the pcreposix library.
2245    5. PCRE was failing to diagnose the case of two named groups with the same
2246    name.
2248    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2249    literal character that is needed in the subject for a match, and scans along to
2250    ensure that it is present before embarking on the full matching process. This
2251    saves time in cases of nested unlimited repeats that are never going to match.
2252    Problem: the scan can take a lot of time if the subject is very long (e.g.
2253    megabytes), thus penalizing straightforward matches. It is now done only if the
2254    amount of subject to be scanned is less than 1000 bytes.
2256    7. A lesser problem with the same optimization is that it was recording the
2257    first character of an anchored pattern as "needed", thus provoking a search
2258    right along the subject, even when the first match of the pattern was going to
2259    fail. The "needed" character is now not set for anchored patterns, unless it
2260    follows something in the pattern that is of non-fixed length. Thus, it still
2261    fulfils its original purpose of finding quick non-matches in cases of nested
2262    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2265    Version 4.0 17-Feb-03
2266    ---------------------
2268    1. If a comment in an extended regex that started immediately after a meta-item
2269    extended to the end of string, PCRE compiled incorrect data. This could lead to
2270    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2272    2. Moved to autoconf 2.53 and libtool 1.4.2.
2274    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2275    the special perltest8 script is no longer needed - all the tests can be run
2276    from a single perltest script.
2278    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2279    by \s. It has now been removed in PCRE. This means it isn't recognized as
2280    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2281    class [:space:] *does* include VT, thereby creating a mess.
2283    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2284    space and tab.
2286    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2287    its new features into the main test script, reducing the number of scripts.
2289    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2290    were backward compatible, and made the (?i) apply to the whole pattern, as if
2291    /i were given. Now it behaves more logically, and applies the option setting
2292    only to what follows. PCRE has been changed to follow suit. However, if it
2293    finds options settings right at the start of the pattern, it extracts them into
2294    the global options, as before. Thus, they show up in the info data.
2296    8. Added support for the \Q...\E escape sequence. Characters in between are
2297    treated as literals. This is slightly different from Perl in that $ and @ are
2298    also handled as literals inside the quotes. In Perl, they will cause variable
2299    interpolation. Note the following examples:
2301        Pattern            PCRE matches      Perl matches
2303        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2304        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2305        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2307    For compatibility with Perl, \Q...\E sequences are recognized inside character
2308    classes as well as outside them.
2310    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2311    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2312    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2313    signed/unsigned warnings.
2315    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2316    option for pcretest, so I've replaced it by a simple function that does just
2317    that job.
2319    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2320    "pcregrep -".
2322    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2323    Java package. This provides some syntactic sugar for simple cases of what my
2324    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2325    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2326    item, you can use this simplified notation. Note that only makes sense with
2327    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2328    greediness, whatever the setting of the PCRE_UNGREEDY option.
2330    13. A change of greediness default within a pattern was not taking effect at
2331    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2332    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2333    was abstracted outside.
2335    14. PCRE now supports the \G assertion. It is true when the current matching
2336    position is at the start point of the match. This differs from \A when the
2337    starting offset is non-zero. Used with the /g option of pcretest (or similar
2338    code), it works in the same way as it does for Perl's /g option. If all
2339    alternatives of a regex begin with \G, the expression is anchored to the start
2340    match position, and the "anchored" flag is set in the compiled expression.
2342    15. Some bugs concerning the handling of certain option changes within patterns
2343    have been fixed. These applied to options other than (?ims). For example,
2344    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2345    been the other way round. Some of this was related to change 7 above.
2347    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2348    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2349    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2350    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2352    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2353    mode. Unlike ".", it always matches newline, whatever the setting of
2354    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2355    assertions. Perl allows it, but it doesn't (in general) work because it can't
2356    calculate the length of the lookbehind. At least, that's the case for Perl
2357    5.8.0 - I've been told they are going to document that it doesn't work in
2358    future.
2360    18. Added an error diagnosis for escapes that PCRE does not support: these are
2361    \L, \l, \N, \P, \p, \U, \u, and \X.
2363    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2364    reading past the end of the pattern in cases such as /[abcd/.
2366    20. PCRE was getting more memory than necessary for patterns with classes that
2367    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2369    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2370    compiling PCRE for use with Virtual Pascal.
2372    22. Small fix to the Makefile to make it work properly if the build is done
2373    outside the source tree.
2375    23. Added a new extension: a condition to go with recursion. If a conditional
2376    subpattern starts with (?(R) the "true" branch is used if recursion has
2377    happened, whereas the "false" branch is used only at the top level.
2379    24. When there was a very long string of literal characters (over 255 bytes
2380    without UTF support, over 250 bytes with UTF support), the computation of how
2381    much memory was required could be incorrect, leading to segfaults or other
2382    strange effects.
2384    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2385    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2386    there was a subsequent back reference to those brackets. This meant that, for
2387    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2388    possible to check for precisely this case. All we can do is abandon the
2389    optimization if .* occurs inside capturing brackets when there are any back
2390    references whatsoever. (See below for a better fix that came later.)
2392    26. The handling of the optimization for finding the first character of a
2393    non-anchored pattern, and for finding a character that is required later in the
2394    match were failing in some cases. This didn't break the matching; it just
2395    failed to optimize when it could. The way this is done has been re-implemented.
2397    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2399    28. Added a new feature that provides some of the functionality that Perl
2400    provides with (?{...}). The facility is termed a "callout". The way it is done
2401    in PCRE is for the caller to provide an optional function, by setting
2402    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2403    global variable. By default it is unset, which disables all calling out. To get
2404    the function called, the regex must include (?C) at appropriate points. This
2405    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2406    This provides a means of identifying different callout points. When PCRE
2407    reaches such a point in the regex, if pcre_callout has been set, the external
2408    function is called. It is provided with data in a structure called
2409    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2410    matching continues; if it returns a non-zero value, the match at the current
2411    point fails. However, backtracking will occur if possible. [This was changed
2412    later and other features added - see item 49 below.]
2414    29. pcretest is upgraded to test the callout functionality. It provides a
2415    callout function that displays information. By default, it shows the start of
2416    the match and the current position in the text. There are some new data escapes
2417    to vary what happens:
2419        \C+         in addition, show current contents of captured substrings
2420        \C-         do not supply a callout function
2421        \C!n        return 1 when callout number n is reached
2422        \C!n!m      return 1 when callout number n is reached for the mth time
2424    30. If pcregrep was called with the -l option and just a single file name, it
2425    output "<stdin>" if a match was found, instead of the file name.
2427    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2428    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2429    pcre_exec(). This saves a malloc/free per call. The default value of
2430    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2431    when configuring.
2433    32. The default maximum size of a compiled pattern is 64K. There have been a
2434    few cases of people hitting this limit. The code now uses macros to handle the
2435    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2436    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2437    configuring. Tests 2 and 5 work only with 2-byte links because they output
2438    debugging information about compiled patterns.
2440    33. Internal code re-arrangements:
2442    (a) Moved the debugging function for printing out a compiled regex into
2443        its own source file (printint.c) and used #include to pull it into
2444        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2445        separate copies.
2447    (b) Defined the list of op-code names for debugging as a macro in
2448        internal.h so that it is next to the definition of the opcodes.
2450    (c) Defined a table of op-code lengths for simpler skipping along compiled
2451        code. This is again a macro in internal.h so that it is next to the
2452        definition of the opcodes.
2454    34. Added support for recursive calls to individual subpatterns, along the
2455    lines of Robin Houston's patch (but implemented somewhat differently).
2457    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2458    allow it to read and process whole directories in Win32. This code was
2459    contributed by Lionel Fourquaux; it has not been tested by me.
2461    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2462    used to name a group. Names consist of alphanumerics and underscores, and must
2463    be unique. Back references use the syntax (?P=name) and recursive calls use
2464    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2465    numbers. The function pcre_fullinfo() can be used after compilation to extract
2466    a name/number map. There are three relevant calls:
2468      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2469      PCRE_INFO_NAMECOUNT            yields the number of entries
2470      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2472    The map is a vector of fixed-size entries. The size of each entry depends on
2473    the length of the longest name used. The first two bytes of each entry are the
2474    group number, most significant byte first. There follows the corresponding
2475    name, zero terminated. The names are in alphabetical order.
2477    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2478    case instead of 255. Making it the same both with and without UTF-8 support
2479    means that the same test output works with both.
2481    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2482    calling malloc() with a zero argument.
2484    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2485    optimization. I've improved things by keeping a bitmap of backreferences with
2486    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2487    fact referenced, the optimization can be applied. It is unlikely that a
2488    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2489    the match to follow \n) will appear inside brackets with a number greater than
2490    31, but if it does, any back reference > 31 suppresses the optimization.
2492    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2493    of disabling numbered capturing parentheses. Any opening parenthesis that is
2494    not followed by ? behaves as if it were followed by ?: but named parentheses
2495    can still be used for capturing (and they will acquire numbers in the usual
2496    way).
2498    41. Redesigned the return codes from the match() function into yes/no/error so
2499    that errors can be passed back from deep inside the nested calls. A malloc
2500    failure while inside a recursive subpattern call now causes the
2501    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2503    42. It is now possible to set a limit on the number of times the match()
2504    function is called in a call to pcre_exec(). This facility makes it possible to
2505    limit the amount of recursion and backtracking, though not in a directly
2506    obvious way, because the match() function is used in a number of different
2507    circumstances. The count starts from zero for each position in the subject
2508    string (for non-anchored patterns). The default limit is, for compatibility, a
2509    large number, namely 10 000 000. You can change this in two ways:
2511    (a) When configuring PCRE before making, you can use --with-match-limit=n
2512        to set a default value for the compiled library.
2514    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2515        a different value is set. See 45 below.
2517    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2519    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2520    of things that can be changed at compile time. The first argument specifies
2521    what is wanted and the second points to where the information is to be placed.
2522    The current list of available information is:
2524      PCRE_CONFIG_UTF8
2526    The output is an integer that is set to one if UTF-8 support is available;
2527    otherwise it is set to zero.
2531    The output is an integer that it set to the value of the code that is used for
2532    newline. It is either LF (10) or CR (13).
2536    The output is an integer that contains the number of bytes used for internal
2537    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2541    The output is an integer that contains the threshold above which the POSIX
2542    interface uses malloc() for output vectors. See item 31 above.
2546    The output is an unsigned integer that contains the default limit of the number
2547    of match() calls in a pcre_exec() execution. See 42 above.
2549    44. pcretest has been upgraded by the addition of the -C option. This causes it
2550    to extract all the available output from the new pcre_config() function, and to
2551    output it. The program then exits immediately.
2553    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2554    order to support additional features. One way would have been to define
2555    pcre_exec2() (for example) with extra arguments, but this would not have been
2556    extensible, and would also have required all calls to the original function to
2557    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2558    is used for passing in "extra" data from pcre_study().
2560    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2561    contains the following fields:
2563      flags         a bitmap indicating which of the following fields are set
2564      study_data    opaque data from pcre_study()
2565      match_limit   a way of specifying a limit on match() calls for a specific
2566                      call to pcre_exec()
2567      callout_data  data for callouts (see 49 below)
2569    The flag bits are also defined in pcre.h, and are
2575    The pcre_study() function now returns one of these new pcre_extra blocks, with
2576    the actual study data pointed to by the study_data field, and the
2577    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2578    before. That is, this change is entirely upwards-compatible and requires no
2579    change to existing code.
2581    If you want to pass in additional data to pcre_exec(), you can either place it
2582    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2583    block.
2585    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2586    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2587    times with different match limits, until it finds the minimum value needed for
2588    pcre_exec() to complete. The value is then output. This can be instructive; for
2589    most simple matches the number is quite small, but for pathological cases it
2590    gets very large very quickly.
2592    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2593    returns the size of the data block pointed to by the study_data field in a
2594    pcre_extra block, that is, the value that was passed as the argument to
2595    pcre_malloc() when PCRE was getting memory in which to place the information
2596    created by pcre_study(). The fourth argument should point to a size_t variable.
2597    pcretest has been extended so that this information is shown after a successful
2598    pcre_study() call when information about the compiled regex is being displayed.
2600    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2601    because what follows is always an absolute path. (Later: it turns out that this
2602    is more than cosmetic for MinGW, because it doesn't like empty path
2603    components.)
2605    49. Some changes have been made to the callout feature (see 28 above):
2607    (i)  A callout function now has three choices for what it returns:
2609           0  =>  success, carry on matching
2610         > 0  =>  failure at this point, but backtrack if possible
2611         < 0  =>  serious error, return this value from pcre_exec()
2613         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2614         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2615         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2616         use by callout functions. It will never be used by PCRE itself.
2618    (ii) The pcre_extra structure (see 45 above) has a void * field called
2619         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2620         pcre_callout_block structure has a field of the same name. The contents of
2621         the field passed in the pcre_extra structure are passed to the callout
2622         function in the corresponding field in the callout block. This makes it
2623         easier to use the same callout-containing regex from multiple threads. For
2624         testing, the pcretest program has a new data escape
2626           \C*n        pass the number n (may be negative) as callout_data
2628         If the callout function in pcretest receives a non-zero value as
2629         callout_data, it returns that value.
2631    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2632    there were some redundant $(CFLAGS) in commands that are now specified as
2633    $(LINK), which already includes $(CFLAGS).
2635    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2636    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2637    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2638    one-byte characters throughout. Note that case-insensitive matching applies
2639    only to characters whose values are less than 256. PCRE doesn't support the
2640    notion of cases for higher-valued characters.
2642    (i)   A character class whose characters are all within 0-255 is handled as
2643          a bit map, and the map is inverted for negative classes. Previously, a
2644          character > 255 always failed to match such a class; however it should
2645          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2647    (ii)  A negated character class with a single character < 255 is coded as
2648          "not this character" (OP_NOT). This wasn't working properly when the test
2649          character was multibyte, either singly or repeated.
2651    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2652          mode, for example: \x{100}{2,3}.
2654    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2655          singly or repeated) now correctly test multibyte characters. However,
2656          PCRE doesn't recognize any characters with values greater than 255 as
2657          digits, spaces, or word characters. Such characters always match \D, \S,
2658          and \W, and never match \d, \s, or \w.
2660    (v)   Classes may now contain characters and character ranges with values
2661          greater than 255. For example: [ab\x{100}-\x{400}].
2663    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2664          PCRE in UTF-8 mode.
2666    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2667    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2668    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2669    value.)
2671    53. The single man page has become too large. I have therefore split it up into
2672    a number of separate man pages. These also give rise to individual HTML pages;
2673    these are now put in a separate directory, and there is an index.html page that
2674    lists them all. Some hyperlinking between the pages has been installed.
2676    54. Added convenience functions for handling named capturing parentheses.
2678    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2679    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2680    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2681    are faulted.
2683    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2684    calling configure. These values are used when compiling the dftables.c program
2685    which is run to generate the source of the default character tables. They
2686    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2687    you will need to set these values.
2689    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2692    Version 3.9 02-Jan-02
2693  ---------------------  ---------------------
2695  1. A bit of extraneous text had somehow crept into the pcregrep documentation.  1. A bit of extraneous text had somehow crept into the pcregrep documentation.

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