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revision 61 by nigel, Sat Feb 24 21:39:58 2007 UTC revision 369 by ph10, Sun Aug 24 16:53:47 2008 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 3.0 02-Jan-02  Version 7.8 25-Aug-08
5    ---------------------
7    1.  Replaced UCP searching code with optimized version as implemented for Ad
8        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
9        stage table and inline lookup instead of a function, giving speed ups of 2
10        to 5 times on some simple patterns that I tested. Permission was given to
11        distribute the MultiStage2.py script that generates the tables (it's not in
12        the tarball, but is in the Subversion repository).
14    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
15        scripts.
17    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
18        a group with a zero qualifier. The result of the study could be incorrect,
19        or the function might crash, depending on the pattern.
21    4.  Caseless matching was not working for non-ASCII characters in back
22        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
23        It now works when Unicode Property Support is available.
25    5.  In pcretest, an escape such as \x{de} in the data was always generating
26        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
27        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
28        truncation.
30    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
32    7.  Added two (int) casts to pcregrep when printing the difference of two
33        pointers, in case they are 64-bit values.
35    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
36        test 2 if it fails.
38    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
39        and a #define of that name to empty if it is not externally set. This is to
40        allow users of MSVC to set it if necessary.
42    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
43        the convenience functions in the pcre_get.c source file.
45    11. An option change at the start of a pattern that had top-level alternatives
46        could cause overwriting and/or a crash. This command provoked a crash in
47        some environments:
49          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
51        This potential security problem was recorded as CVE-2008-2371.
53    12. For a pattern where the match had to start at the beginning or immediately
54        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
55        pcre_dfa_exec() could read past the end of the passed subject if there was
56        no match. To help with detecting such bugs (e.g. with valgrind), I modified
57        pcretest so that it places the subject at the end of its malloc-ed buffer.
59    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
60        exec() might read past the end of the data buffer in UTF-8 mode.
62    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
63        the data contained the byte 0x85 as part of a UTF-8 character within its
64        first line. This applied both to normal and DFA matching.
66    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
67        /^[^d]*?$/8 failed to match "abc".
69    16. Added a missing copyright notice to pcrecpp_internal.h.
71    17. Make it more clear in the documentation that values returned from
72        pcre_exec() in ovector are byte offsets, not character counts.
74    18. Tidied a few places to stop certain compilers from issuing warnings.
77    Version 7.7 07-May-08
78    ---------------------
80    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
81        a string to a long long, pretend we don't even have a long long." This is
82        done by checking for the strtoq, strtoll, and _strtoi64 functions.
84    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
85        pre-7.6 versions, which defined a global no_arg variable instead of putting
86        it in the RE class. (See also #8 below.)
88    3.  Remove a line of dead code, identified by coverity and reported by Nuno
89        Lopes.
91    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
93        (1) The include/exclude patterns were being applied to the whole pathnames
94            of files, instead of just to the final components.
96        (2) If there was more than one level of directory, the subdirectories were
97            skipped unless they satisfied the include/exclude conditions. This is
98            inconsistent with GNU grep (and could even be seen as contrary to the
99            pcregrep specification - which I improved to make it absolutely clear).
100            The action now is always to scan all levels of directory, and just
101            apply the include/exclude patterns to regular files.
103    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
104        --exclude_dir in the tests to avoid scanning .svn directories.
106    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
107        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
108        doesn't support NULs in patterns.
110    7.  Added some missing "const"s to declarations of static tables in
111        pcre_compile.c and pcre_dfa_exec.c.
113    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
114        caused by fix #2  above. (Subsequently also a second patch to fix the
115        first patch. And a third patch - this was a messy problem.)
117    9.  Applied Craig's patch to remove the use of push_back().
119    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
120        matching function regexec().
122    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
123        which, however, unlike Perl's \g{...}, are subroutine calls, not back
124        references. PCRE supports relative numbers with this syntax (I don't think
125        Oniguruma does).
127    12. Previously, a group with a zero repeat such as (...){0} was completely
128        omitted from the compiled regex. However, this means that if the group
129        was called as a subroutine from elsewhere in the pattern, things went wrong
130        (an internal error was given). Such groups are now left in the compiled
131        pattern, with a new opcode that causes them to be skipped at execution
132        time.
134    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
135        to the way PCRE behaves:
137        (a) A lone ] character is dis-allowed (Perl treats it as data).
139        (b) A back reference to an unmatched subpattern matches an empty string
140            (Perl fails the current match path).
142        (c) A data ] in a character class must be notated as \] because if the
143            first data character in a class is ], it defines an empty class. (In
144            Perl it is not possible to have an empty class.) The empty class []
145            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
146            The negative empty class [^] matches any one character, independently
147            of the DOTALL setting.
149    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
150        non-existent subpattern following a character class starting with ']' and
151        containing () gave an internal compiling error instead of "reference to
152        non-existent subpattern". Fortunately, when the pattern did exist, the
153        compiled code was correct. (When scanning forwards to check for the
154        existencd of the subpattern, it was treating the data ']' as terminating
155        the class, so got the count wrong. When actually compiling, the reference
156        was subsequently set up correctly.)
158    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
159        it was being rejected as not supported by pcre_dfa_exec(), even though
160        other assertions are supported. I have made pcre_dfa_exec() support
161        (*FAIL).
163    16. The implementation of 13c above involved the invention of a new opcode,
164        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
165        cannot be changed at match time, I realized I could make a small
166        improvement to matching performance by compiling OP_ALLANY instead of
167        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
168        on the OP_ANY path.
170    17. Compiling pcretest on Windows with readline support failed without the
171        following two fixes: (1) Make the unistd.h include conditional on
172        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
174    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
175        ncurses library to be included for pcretest when ReadLine support is
176        requested, but also to allow for it to be overridden. This patch came from
177        Daniel Bergström.
179    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
180        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
181        any errors with the current Unicode tables. Thanks to Peter Kankowski for
182        spotting this.
185    Version 7.6 28-Jan-08
186    ---------------------
188    1.  A character class containing a very large number of characters with
189        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
190        overflow.
192    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
193        HAVE_LONG_LONG is not defined.
195    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
196        bring them up to date and include new features. This patch includes:
198        - Fixed PH's badly added libz and libbz2 support.
199        - Fixed a problem with static linking.
200        - Added pcredemo. [But later removed - see 7 below.]
201        - Fixed dftables problem and added an option.
202        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
203            HAVE_LONG_LONG.
204        - Added readline support for pcretest.
205        - Added an listing of the option settings after cmake has run.
207    4.  A user submitted a patch to Makefile that makes it easy to create
208        "pcre.dll" under mingw when using Configure/Make. I added stuff to
209        Makefile.am that cause it to include this special target, without
210        affecting anything else. Note that the same mingw target plus all
211        the other distribution libraries and programs are now supported
212        when configuring with CMake (see 6 below) instead of with
213        Configure/Make.
215    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
216        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
217        exported in the Windows port". It has not yet been confirmed that the patch
218        solves the problem, but it does no harm.
220    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
221        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
222        with CMake, and also correct the comment about stack recursion.
224    7.  Remove the automatic building of pcredemo from the ./configure system and
225        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
226        of a program that users should build themselves after PCRE is installed, so
227        building it automatically is not really right. What is more, it gave
228        trouble in some build environments.
230    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
233    Version 7.5 10-Jan-08
234    ---------------------
236    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
237        values in parens when parsing an RE using the C++ wrapper."
239    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
240        Characters greater than 255 were excluded from the class instead of being
241        included.
243    3.  The same bug as (2) above applied to negated POSIX classes such as
244        [:^space:].
246    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
247        defined or documented. It seems to have been a typo for PCRE_STATIC, so
248        I have changed it.
250    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
251        first named subpattern) and a construct such as (?&a) would reference the
252        first named subpattern whose name started with "a" (in other words, the
253        length check was missing). Both these problems are fixed. "Subpattern name
254        expected" is now given for (?&) (a zero-length name), and this patch also
255        makes it give the same error for \k'' (previously it complained that that
256        was a reference to a non-existent subpattern).
258    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
259        this is right because (?- can be followed by option settings as well as by
260        digits. I have, however, made the messages clearer.
262    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
263        than the number used in the conditional) now cause a compile-time error.
264        This is actually not compatible with Perl, which accepts such patterns, but
265        treats the conditional as always being FALSE (as PCRE used to), but it
266        seems to me that giving a diagnostic is better.
268    8.  Change "alphameric" to the more common word "alphanumeric" in comments
269        and messages.
271    9.  Fix two occurrences of "backslash" in comments that should have been
272        "backspace".
274    10. Remove two redundant lines of code that can never be obeyed (their function
275        was moved elsewhere).
277    11. The program that makes PCRE's Unicode character property table had a bug
278        which caused it to generate incorrect table entries for sequences of
279        characters that have the same character type, but are in different scripts.
280        It amalgamated them into a single range, with the script of the first of
281        them. In other words, some characters were in the wrong script. There were
282        thirteen such cases, affecting characters in the following ranges:
284          U+002b0 - U+002c1
285          U+0060c - U+0060d
286          U+0061e - U+00612
287          U+0064b - U+0065e
288          U+0074d - U+0076d
289          U+01800 - U+01805
290          U+01d00 - U+01d77
291          U+01d9b - U+01dbf
292          U+0200b - U+0200f
293          U+030fc - U+030fe
294          U+03260 - U+0327f
295          U+0fb46 - U+0fbb1
296          U+10450 - U+1049d
298    12. The -o option (show only the matching part of a line) for pcregrep was not
299        compatible with GNU grep in that, if there was more than one match in a
300        line, it showed only the first of them. It now behaves in the same way as
301        GNU grep.
303    13. If the -o and -v options were combined for pcregrep, it printed a blank
304        line for every non-matching line. GNU grep prints nothing, and pcregrep now
305        does the same. The return code can be used to tell if there were any
306        non-matching lines.
308    14. Added --file-offsets and --line-offsets to pcregrep.
310    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
311        infinitely looping recursion. The bug was that positive lookaheads were not
312        being skipped when checking for a possible empty match (negative lookaheads
313        and both kinds of lookbehind were skipped).
315    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
316        inclusion of <windows.h> to before rather than after the definition of
317        INVALID_FILE_ATTRIBUTES (patch from David Byron).
319    17. Specifying a possessive quantifier with a specific limit for a Unicode
320        character property caused pcre_compile() to compile bad code, which led at
321        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
322        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
323        caused the error; without that there was no problem.
325    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
327    19. Added --enable-pcretest-libreadline.
329    20. In pcrecpp.cc, the variable 'count' was incremented twice in
330        RE::GlobalReplace(). As a result, the number of replacements returned was
331        double what it should be. I removed one of the increments, but Craig sent a
332        later patch that removed the other one (the right fix) and added unit tests
333        that check the return values (which was not done before).
335    21. Several CMake things:
337        (1) Arranged that, when cmake is used on Unix, the libraries end up with
338            the names libpcre and libpcreposix, not just pcre and pcreposix.
340        (2) The above change means that pcretest and pcregrep are now correctly
341            linked with the newly-built libraries, not previously installed ones.
345    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
346        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
347        UTF-8 newline character). The key issue is that the pattern starts .*;
348        this means that the match must be either at the beginning, or after a
349        newline. The bug was in the code for advancing after a failed match and
350        checking that the new position followed a newline. It was not taking
351        account of UTF-8 characters correctly.
353    23. PCRE was behaving differently from Perl in the way it recognized POSIX
354        character classes. PCRE was not treating the sequence [:...:] as a
355        character class unless the ... were all letters. Perl, however, seems to
356        allow any characters between [: and :], though of course it rejects as
357        unknown any "names" that contain non-letters, because all the known class
358        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
359        for example, whereas PCRE did not - it did not recognize a POSIX character
360        class. This seemed a bit dangerous, so the code has been changed to be
361        closer to Perl. The behaviour is not identical to Perl, because PCRE will
362        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
363        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
364        Perl does, and where it didn't before.
366    24. Rewrite so as to remove the single use of %n from pcregrep because in some
367        Windows environments %n is disabled by default.
370    Version 7.4 21-Sep-07
371    ---------------------
373    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
374        means that a class such as [\s] counted as "explicit reference to CR or
375        LF". That isn't really right - the whole point of the change was to try to
376        help when there was an actual mention of one of the two characters. So now
377        the change happens only if \r or \n (or a literal CR or LF) character is
378        encountered.
380    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
381        of both had grown to the point where there were only 3 bits left.
382        Fortunately, there was spare space in the data structure, and so I have
383        moved the internal flags into a new 16-bit field to free up more option
384        bits.
386    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
387        but did not set the internal JCHANGED flag - either of these is enough to
388        control the way the "get" function works - but the PCRE_INFO_JCHANGED
389        facility is supposed to tell if (?J) was ever used, so now (?J) at the
390        start sets both bits.
392    4.  Added options (at build time, compile time, exec time) to change \R from
393        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
395    5.  doc/pcresyntax.html was missing from the distribution.
397    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
398        compatibility, even though it is no longer used.
400    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
401        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
402        windows.h file is present (where different names are used). [This was
403        reversed later after testing - see 16 below.]
405    8.  Changed all #include <config.h> to #include "config.h". There were also
406        some further <pcre.h> cases that I changed to "pcre.h".
408    9.  When pcregrep was used with the --colour option, it missed the line ending
409        sequence off the lines that it output.
411    10. It was pointed out to me that arrays of string pointers cause lots of
412        relocations when a shared library is dynamically loaded. A technique of
413        using a single long string with a table of offsets can drastically reduce
414        these. I have refactored PCRE in four places to do this. The result is
415        dramatic:
417          Originally:                          290
418          After changing UCP table:            187
419          After changing error message table:   43
420          After changing table of "verbs"       36
421          After changing table of Posix names   22
423        Thanks to the folks working on Gregex for glib for this insight.
425    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
426        unicode-properties was also set.
428    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
430    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
431        checked only for CRLF.
433    14. Added casts to pcretest.c to avoid compiler warnings.
435    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
437    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
438        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
439        entirely. This removes changes made in 7 above.
441    17. The CMake files have been updated, and there is now more information about
442        building with CMake in the NON-UNIX-USE document.
445    Version 7.3 28-Aug-07
446    ---------------------
448     1. In the rejigging of the build system that eventually resulted in 7.1, the
449        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
450        brackets there is not right, since it causes compilers to look for an
451        installed pcre.h, not the version that is in the source that is being
452        compiled (which of course may be different). I have changed it back to:
454          #include "pcre.h"
456        I have a vague recollection that the change was concerned with compiling in
457        different directories, but in the new build system, that is taken care of
458        by the VPATH setting the Makefile.
460     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
461        when the subject happened to end in the byte 0x85 (e.g. if the last
462        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
463        characters but of course it shouldn't be taken as a newline when it is part
464        of another character. The bug was that, for an unlimited repeat of . in
465        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
466        characters when looking for a newline.
468     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
470     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
471        in debug output.
473     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
474        long printing in the pcrecpp unittest when running under MinGW.
476     6. ESC_K was left out of the EBCDIC table.
478     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
479        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
480        limit also applies to "virtual nesting" when a pattern is recursive, and in
481        this case 1000 isn't so big. I have been able to remove this limit at the
482        expense of backing off one optimization in certain circumstances. Normally,
483        when pcre_exec() would call its internal match() function recursively and
484        immediately return the result unconditionally, it uses a "tail recursion"
485        feature to save stack. However, when a subpattern that can match an empty
486        string has an unlimited repetition quantifier, it no longer makes this
487        optimization. That gives it a stack frame in which to save the data for
488        checking that an empty string has been matched. Previously this was taken
489        from the 1000-entry workspace that had been reserved. So now there is no
490        explicit limit, but more stack is used.
492     8. Applied Daniel's patches to solve problems with the import/export magic
493        syntax that is required for Windows, and which was going wrong for the
494        pcreposix and pcrecpp parts of the library. These were overlooked when this
495        problem was solved for the main library.
497     9. There were some crude static tests to avoid integer overflow when computing
498        the size of patterns that contain repeated groups with explicit upper
499        limits. As the maximum quantifier is 65535, the maximum group length was
500        set at 30,000 so that the product of these two numbers did not overflow a
501        32-bit integer. However, it turns out that people want to use groups that
502        are longer than 30,000 bytes (though not repeat them that many times).
503        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
504        made it possible to implement the integer overflow checks in a much more
505        dynamic way, which I have now done. The artificial limitation on group
506        length has been removed - we now have only the limit on the total length of
507        the compiled pattern, which depends on the LINK_SIZE setting.
509    10. Fixed a bug in the documentation for get/copy named substring when
510        duplicate names are permitted. If none of the named substrings are set, the
511        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
512        empty string.
514    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
515        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
516        because the ] is interpreted as the first data character and the
517        terminating ] is not found. PCRE has been made compatible with Perl in this
518        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
519        cause memory overwriting.
521    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
522        string has been matched (to stop an infinite loop). It was not recognizing
523        a conditional subpattern that could match an empty string if that
524        subpattern was within another subpattern. For example, it looped when
525        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
526        condition was not nested. This bug has been fixed.
528    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
529        past the start of the subject in the presence of bytes with the top bit
530        set, for example "\x8aBCD".
532    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
533        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
535    14. Optimized (?!) to (*FAIL).
537    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
538        This restricts code points to be within the range 0 to 0x10FFFF, excluding
539        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
540        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
541        does: it's just the validity check that is more restrictive.
543    16. Inserted checks for integer overflows during escape sequence (backslash)
544        processing, and also fixed erroneous offset values for syntax errors during
545        backslash processing.
547    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
548        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
550    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
551        caused an overrun.
553    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
554        something other than just ASCII characters) inside a group that had an
555        unlimited repeat caused a loop at compile time (while checking to see
556        whether the group could match an empty string).
558    20. Debugging a pattern containing \p or \P could cause a crash. For example,
559        [\P{Any}] did so. (Error in the code for printing property names.)
561    21. An orphan \E inside a character class could cause a crash.
563    22. A repeated capturing bracket such as (A)? could cause a wild memory
564        reference during compilation.
566    23. There are several functions in pcre_compile() that scan along a compiled
567        expression for various reasons (e.g. to see if it's fixed length for look
568        behind). There were bugs in these functions when a repeated \p or \P was
569        present in the pattern. These operators have additional parameters compared
570        with \d, etc, and these were not being taken into account when moving along
571        the compiled data. Specifically:
573        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
574            length.
576        (b) An item such as \pL+ within a repeated group could cause crashes or
577            loops.
579        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
580            "reference to non-existent subpattern" error.
582        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
584    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
585        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
587    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
589    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
590        character were causing crashes (broken optimization).
592    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
593        \p or \P) caused a compile-time loop.
595    28. More problems have arisen in unanchored patterns when CRLF is a valid line
596        break. For example, the unstudied pattern [\r\n]A does not match the string
597        "\r\nA" because change 7.0/46 below moves the current point on by two
598        characters after failing to match at the start. However, the pattern \nA
599        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
600        the same is true. There doesn't seem any very clean way out of this, but
601        what I have chosen to do makes the common cases work: PCRE now takes note
602        of whether there can be an explicit match for \r or \n anywhere in the
603        pattern, and if so, 7.0/46 no longer applies. As part of this change,
604        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
605        pattern has explicit CR or LF references.
607    29. Added (*CR) etc for changing newline setting at start of pattern.
610    Version 7.2 19-Jun-07
611    ---------------------
613     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
614        which is apparently normally available under Windows.
616     2. Re-jig the pcregrep tests with different newline settings in an attempt
617        to make them independent of the local environment's newline setting.
619     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
621     4. Some of the "internals" tests were previously cut out when the link size
622        was not 2, because the output contained actual offsets. The recent new
623        "Z" feature of pcretest means that these can be cut out, making the tests
624        usable with all link sizes.
626     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
627        stack recursion. This gives a massive performance boost under BSD, but just
628        a small improvement under Linux. However, it saves one field in the frame
629        in all cases.
631     6. Added more features from the forthcoming Perl 5.10:
633        (a) (?-n) (where n is a string of digits) is a relative subroutine or
634            recursion call. It refers to the nth most recently opened parentheses.
636        (b) (?+n) is also a relative subroutine call; it refers to the nth next
637            to be opened parentheses.
639        (c) Conditions that refer to capturing parentheses can be specified
640            relatively, for example, (?(-2)... or (?(+3)...
642        (d) \K resets the start of the current match so that everything before
643            is not part of it.
645        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
647        (f) \g{name} is another synonym - part of Perl 5.10's unification of
648            reference syntax.
650        (g) (?| introduces a group in which the numbering of parentheses in each
651            alternative starts with the same number.
653        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
655     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
658     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
659        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
660        for detecting groups that can match an empty string.
662     9. A pattern with a very large number of alternatives (more than several
663        hundred) was running out of internal workspace during the pre-compile
664        phase, where pcre_compile() figures out how much memory will be needed. A
665        bit of new cunning has reduced the workspace needed for groups with
666        alternatives. The 1000-alternative test pattern now uses 12 bytes of
667        workspace instead of running out of the 4096 that are available.
669    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
671    11. Applied patch from Google to remove an optimization that didn't quite work.
672        The report of the bug said:
674          pcrecpp::RE("a*").FullMatch("aaa") matches, while
675          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
676          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
678    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
679        it matched the wrong number of bytes.
682    Version 7.1 24-Apr-07
683    ---------------------
685     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
686        that is more "standard", making use of automake and other Autotools. There
687        is some re-arrangement of the files and adjustment of comments consequent
688        on this.
690     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
691        for recursive directory scanning broke on some systems because the files
692        are not scanned in any specific order and on different systems the order
693        was different. A call to "sort" has been inserted into RunGrepTest for the
694        approprate test as a short-term fix. In the longer term there may be an
695        alternative.
697     3. I had an email from Eric Raymond about problems translating some of PCRE's
698        man pages to HTML (despite the fact that I distribute HTML pages, some
699        people do their own conversions for various reasons). The problems
700        concerned the use of low-level troff macros .br and .in. I have therefore
701        removed all such uses from the man pages (some were redundant, some could
702        be replaced by .nf/.fi pairs). The 132html script that I use to generate
703        HTML has been updated to handle .nf/.fi and to complain if it encounters
704        .br or .in.
706     4. Updated comments in configure.ac that get placed in config.h.in and also
707        arranged for config.h to be included in the distribution, with the name
708        config.h.generic, for the benefit of those who have to compile without
709        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
711     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
712        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
713        makevp.bat for the current PCRE, using the additional files
714        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
716     6. A Windows user reported a minor discrepancy with test 2, which turned out
717        to be caused by a trailing space on an input line that had got lost in his
718        copy. The trailing space was an accident, so I've just removed it.
720     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
721        that is needed.
723     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
724        as "const" (a) because they are and (b) because it helps the PHP
725        maintainers who have recently made a script to detect big data structures
726        in the php code that should be moved to the .rodata section. I remembered
727        to update Builducptable as well, so it won't revert if ucptable.h is ever
728        re-created.
730     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
731        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
732        order to be able to cut out the UTF-8 tables in the latter when UTF-8
733        support is not required. This saves 1.5-2K of code, which is important in
734        some applications.
736        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
737        so as not to refer to the tables, even though these functions will never be
738        called when UTF-8 support is disabled. Otherwise there are problems with a
739        shared library.
741    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
743        (a) It was defining its arguments as char * instead of void *.
745        (b) It was assuming that all moves were upwards in memory; this was true
746            a long time ago when I wrote it, but is no longer the case.
748        The emulated memove() is provided for those environments that have neither
749        memmove() nor bcopy(). I didn't think anyone used it these days, but that
750        is clearly not the case, as these two bugs were recently reported.
752    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
753        and Detrail to create the HTML documentation, the .txt form of the man
754        pages, and it removes trailing spaces from listed files. It also creates
755        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
756        case, it wraps all the #defines with #ifndefs. This script should be run
757        before "make dist".
759    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
760        with Unicode property support.
762        (a) For a maximizing quantifier, if the two different cases of the
763            character were of different lengths in their UTF-8 codings (there are
764            some cases like this - I found 11), and the matching function had to
765            back up over a mixture of the two cases, it incorrectly assumed they
766            were both the same length.
768        (b) When PCRE was configured to use the heap rather than the stack for
769            recursion during matching, it was not correctly preserving the data for
770            the other case of a UTF-8 character when checking ahead for a match
771            while processing a minimizing repeat. If the check also involved
772            matching a wide character, but failed, corruption could cause an
773            erroneous result when trying to check for a repeat of the original
774            character.
776    13. Some tidying changes to the testing mechanism:
778        (a) The RunTest script now detects the internal link size and whether there
779            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
780            values substituted by "configure". (The RunGrepTest script already did
781            this for UTF-8.) The configure.ac script no longer substitutes the
782            relevant variables.
784        (b) The debugging options /B and /D in pcretest show the compiled bytecode
785            with length and offset values. This means that the output is different
786            for different internal link sizes. Test 2 is skipped for link sizes
787            other than 2 because of this, bypassing the problem. Unfortunately,
788            there was also a test in test 3 (the locale tests) that used /B and
789            failed for link sizes other than 2. Rather than cut the whole test out,
790            I have added a new /Z option to pcretest that replaces the length and
791            offset values with spaces. This is now used to make test 3 independent
792            of link size. (Test 2 will be tidied up later.)
794    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
795        segmentation fault instead of returning the appropriate error message.
797    15. In multiline mode when the newline sequence was set to "any", the pattern
798        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
799        This doesn't seem right; it now treats the CRLF combination as the line
800        ending, and so does not match in that case. It's only a pattern such as ^$
801        that would hit this one: something like ^ABC$ would have failed after \r
802        and then tried again after \r\n.
804    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
805        in an attempt to make files that differ only in their line terminators
806        compare equal. This works on Linux.
808    17. Under certain error circumstances pcregrep might try to free random memory
809        as it exited. This is now fixed, thanks to valgrind.
811    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
812        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
813        was because its rules for how to advance for /g after matching an empty
814        string at the end of a line did not allow for this case. They now check for
815        it specially.
817    20. pcretest is supposed to handle patterns and data of any length, by
818        extending its buffers when necessary. It was getting this wrong when the
819        buffer for a data line had to be extended.
821    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
822        CRLF as a newline sequence.
824    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
825        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
826        I have nevertheless tidied it up.
828    23. Added some casts to kill warnings from HP-UX ia64 compiler.
830    24. Added a man page for pcre-config.
833    Version 7.0 19-Dec-06
834    ---------------------
836     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
837        moving to gcc 4.1.1.
839     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
840        sys/time.h, which is documented as needed for this function. It doesn't
841        seem to matter on Linux, but it showed up on some releases of OS X.
843     3. It seems that there are systems where bytes whose values are greater than
844        127 match isprint() in the "C" locale. The "C" locale should be the
845        default when a C program starts up. In most systems, only ASCII printing
846        characters match isprint(). This difference caused the output from pcretest
847        to vary, making some of the tests fail. I have changed pcretest so that:
849        (a) When it is outputting text in the compiled version of a pattern, bytes
850            other than 32-126 are always shown as hex escapes.
852        (b) When it is outputting text that is a matched part of a subject string,
853            it does the same, unless a different locale has been set for the match
854            (using the /L modifier). In this case, it uses isprint() to decide.
856     4. Fixed a major bug that caused incorrect computation of the amount of memory
857        required for a compiled pattern when options that changed within the
858        pattern affected the logic of the preliminary scan that determines the
859        length. The relevant options are -x, and -i in UTF-8 mode. The result was
860        that the computed length was too small. The symptoms of this bug were
861        either the PCRE error "internal error: code overflow" from pcre_compile(),
862        or a glibc crash with a message such as "pcretest: free(): invalid next
863        size (fast)". Examples of patterns that provoked this bug (shown in
864        pcretest format) are:
866          /(?-x: )/x
867          /(?x)(?-x: \s*#\s*)/
868          /((?i)[\x{c0}])/8
869          /(?i:[\x{c0}])/8
871        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
872        is now done differently.
874     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
875        wrapper classes; (b) implement a new function in the C++ scanner that is
876        more efficient than the old way of doing things because it avoids levels of
877        recursion in the regex matching; (c) add a paragraph to the documentation
878        for the FullMatch() function.
880     6. The escape sequence \n was being treated as whatever was defined as
881        "newline". Not only was this contrary to the documentation, which states
882        that \n is character 10 (hex 0A), but it also went horribly wrong when
883        "newline" was defined as CRLF. This has been fixed.
885     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
886        was being set to -1 for the "end of line" case (supposedly a value that no
887        character can have). Though this value is never used (the check for end of
888        line is "zero bytes in current character"), it caused compiler complaints.
889        I've changed it to 0xffffffff.
891     8. In pcre_version.c, the version string was being built by a sequence of
892        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
893        string (as it is for production releases) called a macro with an empty
894        argument. The C standard says the result of this is undefined. The gcc
895        compiler treats it as an empty string (which was what was wanted) but it is
896        reported that Visual C gives an error. The source has been hacked around to
897        avoid this problem.
899     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
900        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
901        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
902        of them did).
904    10. Originally, pcretest opened its input and output without "b"; then I was
905        told that "b" was needed in some environments, so it was added for release
906        5.0 to both the input and output. (It makes no difference on Unix-like
907        systems.) Later I was told that it is wrong for the input on Windows. I've
908        now abstracted the modes into two macros, to make it easier to fiddle with
909        them, and removed "b" from the input mode under Windows.
911    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
913    12. Added -help and --help to pcretest as an official way of being reminded
914        of the options.
916    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
917        and pcrecpp.cc because they annoy compilers at high warning levels.
919    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
921    15. Fixed an occurrence of == in configure.ac that should have been = (shell
922        scripts are not C programs :-) and which was not noticed because it works
923        on Linux.
925    16. pcretest is supposed to handle any length of pattern and data line (as one
926        line or as a continued sequence of lines) by extending its input buffer if
927        necessary. This feature was broken for very long pattern lines, leading to
928        a string of junk being passed to pcre_compile() if the pattern was longer
929        than about 50K.
931    17. I have done a major re-factoring of the way pcre_compile() computes the
932        amount of memory needed for a compiled pattern. Previously, there was code
933        that made a preliminary scan of the pattern in order to do this. That was
934        OK when PCRE was new, but as the facilities have expanded, it has become
935        harder and harder to keep it in step with the real compile phase, and there
936        have been a number of bugs (see for example, 4 above). I have now found a
937        cunning way of running the real compile function in a "fake" mode that
938        enables it to compute how much memory it would need, while actually only
939        ever using a few hundred bytes of working memory and without too many
940        tests of the mode. This should make future maintenance and development
941        easier. A side effect of this work is that the limit of 200 on the nesting
942        depth of parentheses has been removed (though this was never a serious
943        limitation, I suspect). However, there is a downside: pcre_compile() now
944        runs more slowly than before (30% or more, depending on the pattern). I
945        hope this isn't a big issue. There is no effect on runtime performance.
947    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
948        newline (only possible for the last line of a file) and it was a
949        pattern that set a locale (followed by /Lsomething), pcretest crashed.
951    19. Added additional timing features to pcretest. (1) The -tm option now times
952        matching only, not compiling. (2) Both -t and -tm can be followed, as a
953        separate command line item, by a number that specifies the number of
954        repeats to use when timing. The default is 50000; this gives better
955        precision, but takes uncomfortably long for very large patterns.
957    20. Extended pcre_study() to be more clever in cases where a branch of a
958        subpattern has no definite first character. For example, (a*|b*)[cd] would
959        previously give no result from pcre_study(). Now it recognizes that the
960        first character must be a, b, c, or d.
962    21. There was an incorrect error "recursive call could loop indefinitely" if
963        a subpattern (or the entire pattern) that was being tested for matching an
964        empty string contained only one non-empty item after a nested subpattern.
965        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
966        incorrectly, because the \d was being skipped in the check.
968    22. The pcretest program now has a new pattern option /B and a command line
969        option -b, which is equivalent to adding /B to every pattern. This causes
970        it to show the compiled bytecode, without the additional information that
971        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
972        is the same as /B/I).
974    23. A new optimization is now able automatically to treat some sequences such
975        as a*b as a*+b. More specifically, if something simple (such as a character
976        or a simple class like \d) has an unlimited quantifier, and is followed by
977        something that cannot possibly match the quantified thing, the quantifier
978        is automatically "possessified".
980    24. A recursive reference to a subpattern whose number was greater than 39
981        went wrong under certain circumstances in UTF-8 mode. This bug could also
982        have affected the operation of pcre_study().
984    25. Realized that a little bit of performance could be had by replacing
985        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
987    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
989    27. Possessive quantifiers such as a++ were previously implemented by turning
990        them into atomic groups such as ($>a+). Now they have their own opcodes,
991        which improves performance. This includes the automatically created ones
992        from 23 above.
994    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
995        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
996        the first matched character to be a colon. This applied both to named and
997        numbered groups.
999    29. The ucpinternal.h header file was missing its idempotency #ifdef.
1001    30. I was sent a "project" file called libpcre.a.dev which I understand makes
1002        building PCRE on Windows easier, so I have included it in the distribution.
1004    31. There is now a check in pcretest against a ridiculously large number being
1005        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
1006        loop, the loop is abandoned.
1008    32. Forward references to subpatterns in conditions such as (?(2)...) where
1009        subpattern 2 is defined later cause pcre_compile() to search forwards in
1010        the pattern for the relevant set of parentheses. This search went wrong
1011        when there were unescaped parentheses in a character class, parentheses
1012        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
1014    33. "Subroutine" calls and backreferences were previously restricted to
1015        referencing subpatterns earlier in the regex. This restriction has now
1016        been removed.
1018    34. Added a number of extra features that are going to be in Perl 5.10. On the
1019        whole, these are just syntactic alternatives for features that PCRE had
1020        previously implemented using the Python syntax or my own invention. The
1021        other formats are all retained for compatibility.
1023        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
1024            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
1025            also .NET compatible.
1027        (b) A recursion or subroutine call to a named group can now be defined as
1028            (?&name) as well as (?P>name).
1030        (c) A backreference to a named group can now be defined as \k<name> or
1031            \k'name' as well as (?P=name). The new forms, as well as being in Perl
1032            5.10, are also .NET compatible.
1034        (d) A conditional reference to a named group can now use the syntax
1035            (?(<name>) or (?('name') as well as (?(name).
1037        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
1038            groups (named and numbered) that are never evaluated inline, but can be
1039            called as "subroutines" from elsewhere. In effect, the DEFINE condition
1040            is always false. There may be only one alternative in such a group.
1042        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
1043            as the simple (?(R). The condition is true only if the most recent
1044            recursion is that of the given number or name. It does not search out
1045            through the entire recursion stack.
1047        (g) The escape \gN or \g{N} has been added, where N is a positive or
1048            negative number, specifying an absolute or relative reference.
1050    35. Tidied to get rid of some further signed/unsigned compiler warnings and
1051        some "unreachable code" warnings.
1053    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
1054        things, this adds five new scripts.
1056    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
1057        There were also incompatibilities regarding the handling of \Q..\E inside
1058        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
1059        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
1061    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
1062        matches an empty string, and forcibly breaks the loop. There were bugs in
1063        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
1064        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
1065        separate and independent bugs (that affected different cases) have been
1066        fixed.
1068    39. Refactored the code to abolish the use of different opcodes for small
1069        capturing bracket numbers. This is a tidy that I avoided doing when I
1070        removed the limit on the number of capturing brackets for 3.5 back in 2001.
1071        The new approach is not only tidier, it makes it possible to reduce the
1072        memory needed to fix the previous bug (38).
1074    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
1075        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
1076        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
1077        mode.
1079    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
1080        report.
1082    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
1083        copy construction and assignment in the C++ wrapper.
1085    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
1086        couple of bugs that could have given wrong results in the "--newline=crlf"
1087        case.
1089    44. Added a number of casts and did some reorganization of signed/unsigned int
1090        variables following suggestions from Dair Grant. Also renamed the variable
1091        "this" as "item" because it is a C++ keyword.
1093    45. Arranged for dftables to add
1095          #include "pcre_internal.h"
1097        to pcre_chartables.c because without it, gcc 4.x may remove the array
1098        definition from the final binary if PCRE is built into a static library and
1099        dead code stripping is activated.
1101    46. For an unanchored pattern, if a match attempt fails at the start of a
1102        newline sequence, and the newline setting is CRLF or ANY, and the next two
1103        characters are CRLF, advance by two characters instead of one.
1106    Version 6.7 04-Jul-06
1107    ---------------------
1109     1. In order to handle tests when input lines are enormously long, pcretest has
1110        been re-factored so that it automatically extends its buffers when
1111        necessary. The code is crude, but this _is_ just a test program. The
1112        default size has been increased from 32K to 50K.
1114     2. The code in pcre_study() was using the value of the re argument before
1115        testing it for NULL. (Of course, in any sensible call of the function, it
1116        won't be NULL.)
1118     3. The memmove() emulation function in pcre_internal.h, which is used on
1119        systems that lack both memmove() and bcopy() - that is, hardly ever -
1120        was missing a "static" storage class specifier.
1122     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1123        containing an extended class (one that cannot be represented by a bitmap
1124        because it contains high-valued characters or Unicode property items, e.g.
1125        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1126        pattern, but PCRE should not loop if you do not (it no longer does).
1127        [Detail: two cases were found: (a) a repeated subpattern containing an
1128        extended class; (b) a recursive reference to a subpattern that followed a
1129        previous extended class. It wasn't skipping over the extended class
1130        correctly when UTF-8 mode was not set.]
1132     5. A negated single-character class was not being recognized as fixed-length
1133        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1134        compile error "lookbehind assertion is not fixed length".
1136     6. The RunPerlTest auxiliary script was showing an unexpected difference
1137        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1138        write a Perl script that can interpret lines of an input file either as
1139        byte characters or as UTF-8, which is what "perltest" was being required to
1140        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1141        can't do is switch easily at run time between having the "use utf8;" pragma
1142        or not. In the end, I fudged it by using the RunPerlTest script to insert
1143        "use utf8;" explicitly for the UTF-8 tests.
1145     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1146        the end of the subject string, contrary to the documentation and to what
1147        Perl does. This was true of both matching functions. Now it matches only at
1148        the start of the subject and immediately after *internal* newlines.
1150     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1151        a pointer to an int instead of a pointer to an unsigned long int. This
1152        caused problems on 64-bit systems.
1154     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1155        instance of the 'standard' template library not being so standard".
1157    10. There was no check on the number of named subpatterns nor the maximum
1158        length of a subpattern name. The product of these values is used to compute
1159        the size of the memory block for a compiled pattern. By supplying a very
1160        long subpattern name and a large number of named subpatterns, the size
1161        computation could be caused to overflow. This is now prevented by limiting
1162        the length of names to 32 characters, and the number of named subpatterns
1163        to 10,000.
1165    11. Subpatterns that are repeated with specific counts have to be replicated in
1166        the compiled pattern. The size of memory for this was computed from the
1167        length of the subpattern and the repeat count. The latter is limited to
1168        65535, but there was no limit on the former, meaning that integer overflow
1169        could in principle occur. The compiled length of a repeated subpattern is
1170        now limited to 30,000 bytes in order to prevent this.
1172    12. Added the optional facility to have named substrings with the same name.
1174    13. Added the ability to use a named substring as a condition, using the
1175        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1176        are numbers (not recommended). Forward references are permitted.
1178    14. Added forward references in named backreferences (if you see what I mean).
1180    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1181        pattern could run off the end of the subject. For example, the pattern
1182        "(?s)(.{1,5})"8 did this with the subject "ab".
1184    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1185        PCRE_CASELESS was set when matching characters that were quantified with ?
1186        or *.
1188    17. A character class other than a single negated character that had a minimum
1189        but no maximum quantifier - for example [ab]{6,} - was not handled
1190        correctly by pce_dfa_exec(). It would match only one character.
1192    18. A valid (though odd) pattern that looked like a POSIX character
1193        class but used an invalid character after [ (for example [[,abc,]]) caused
1194        pcre_compile() to give the error "Failed: internal error: code overflow" or
1195        in some cases to crash with a glibc free() error. This could even happen if
1196        the pattern terminated after [[ but there just happened to be a sequence of
1197        letters, a binary zero, and a closing ] in the memory that followed.
1199    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1200        over the years. Originally (before any Unicode support), just the bottom 8
1201        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1202        output from "man perlunicode" includes this:
1204          The regular expression compiler produces polymorphic opcodes.  That
1205          is, the pattern adapts to the data and automatically switches to
1206          the Unicode character scheme when presented with Unicode data--or
1207          instead uses a traditional byte scheme when presented with byte
1208          data.
1210        Sadly, a wide octal escape does not cause a switch, and in a string with
1211        no other multibyte characters, these octal escapes are treated as before.
1212        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1213        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1214        Unicode string.
1216        I have not perpetrated such confusion in PCRE. Up till now, it took just
1217        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1218        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1219        translate to the appropriate multibyte character.
1221    29. Applied some refactoring to reduce the number of warnings from Microsoft
1222        and Borland compilers. This has included removing the fudge introduced
1223        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1224        a warning about an unused variable.
1226    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1227        characters since release 4.0, because Perl (from release 5.004) does not.
1228        [Or at least, is documented not to: some releases seem to be in conflict
1229        with the documentation.] However, when a pattern was studied with
1230        pcre_study() and all its branches started with \s, PCRE still included VT
1231        as a possible starting character. Of course, this did no harm; it just
1232        caused an unnecessary match attempt.
1234    22. Removed a now-redundant internal flag bit that recorded the fact that case
1235        dependency changed within the pattern. This was once needed for "required
1236        byte" processing, but is no longer used. This recovers a now-scarce options
1237        bit. Also moved the least significant internal flag bit to the most-
1238        significant bit of the word, which was not previously used (hangover from
1239        the days when it was an int rather than a uint) to free up another bit for
1240        the future.
1242    23. Added support for CRLF line endings as well as CR and LF. As well as the
1243        default being selectable at build time, it can now be changed at runtime
1244        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1245        specify that it is scanning data with non-default line endings.
1247    24. Changed the definition of CXXLINK to make it agree with the definition of
1248        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1250    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1251        recursions. This makes a big different to stack usage for some patterns.
1253    26. If a subpattern containing a named recursion or subroutine reference such
1254        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1255        the space required for the compiled pattern went wrong and gave too small a
1256        value. Depending on the environment, this could lead to "Failed: internal
1257        error: code overflow at offset 49" or "glibc detected double free or
1258        corruption" errors.
1260    27. Applied patches from Google (a) to support the new newline modes and (b) to
1261        advance over multibyte UTF-8 characters in GlobalReplace.
1263    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1264        difference for some implementation of PCRE in some Windows version.
1266    29. Added some extra testing facilities to pcretest:
1268        \q<number>   in a data line sets the "match limit" value
1269        \Q<number>   in a data line sets the "match recursion limt" value
1270        -S <number>  sets the stack size, where <number> is in megabytes
1272        The -S option isn't available for Windows.
1275    Version 6.6 06-Feb-06
1276    ---------------------
1278     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1279        in pcreposix.h. I have copied the definition from pcre.h.
1281     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1282        because pcre.h is no longer a built file.
1284     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1285        not normally included in the compiled code.
1288    Version 6.5 01-Feb-06
1289    ---------------------
1291     1. When using the partial match feature with pcre_dfa_exec(), it was not
1292        anchoring the second and subsequent partial matches at the new starting
1293        point. This could lead to incorrect results. For example, with the pattern
1294        /1234/, partially matching against "123" and then "a4" gave a match.
1296     2. Changes to pcregrep:
1298        (a) All non-match returns from pcre_exec() were being treated as failures
1299            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1300            error message is output. Some extra information is given for the
1301            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1302            probably the only errors that are likely to be caused by users (by
1303            specifying a regex that has nested indefinite repeats, for instance).
1304            If there are more than 20 of these errors, pcregrep is abandoned.
1306        (b) A binary zero was treated as data while matching, but terminated the
1307            output line if it was written out. This has been fixed: binary zeroes
1308            are now no different to any other data bytes.
1310        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1311            used to set a locale for matching. The --locale=xxxx long option has
1312            been added (no short equivalent) to specify a locale explicitly on the
1313            pcregrep command, overriding the environment variables.
1315        (d) When -B was used with -n, some line numbers in the output were one less
1316            than they should have been.
1318        (e) Added the -o (--only-matching) option.
1320        (f) If -A or -C was used with -c (count only), some lines of context were
1321            accidentally printed for the final match.
1323        (g) Added the -H (--with-filename) option.
1325        (h) The combination of options -rh failed to suppress file names for files
1326            that were found from directory arguments.
1328        (i) Added the -D (--devices) and -d (--directories) options.
1330        (j) Added the -F (--fixed-strings) option.
1332        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1334        (l) Added the --colo(u)r option.
1336        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1337            is not present by default.
1339     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1340        items such as (?R) or (?1), when the recursion could match a number of
1341        alternatives. If it matched one of the alternatives, but subsequently,
1342        outside the recursion, there was a failure, the code tried to back up into
1343        the recursion. However, because of the way PCRE is implemented, this is not
1344        possible, and the result was an incorrect result from the match.
1346        In order to prevent this happening, the specification of recursion has
1347        been changed so that all such subpatterns are automatically treated as
1348        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1350     4. I had overlooked the fact that, in some locales, there are characters for
1351        which isalpha() is true but neither isupper() nor islower() are true. In
1352        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1353        and ordfeminine) are like this. This affected the treatment of \w and \W
1354        when they appeared in character classes, but not when they appeared outside
1355        a character class. The bit map for "word" characters is now created
1356        separately from the results of isalnum() instead of just taking it from the
1357        upper, lower, and digit maps. (Plus the underscore character, of course.)
1359     5. The above bug also affected the handling of POSIX character classes such as
1360        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1361        permanent tables. Instead, the bit maps for such a class were previously
1362        created as the appropriate unions of the upper, lower, and digit bitmaps.
1363        Now they are created by subtraction from the [[:word:]] class, which has
1364        its own bitmap.
1366     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1367        It is created by subtracting the vertical space characters (\x09, \x0a,
1368        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1369        subtraction was done in the overall bitmap for a character class, meaning
1370        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1371        be recognized. This bug has been fixed.
1373     7. Patches from the folks at Google:
1375          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1376          real life, but is still worth protecting against".
1378          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1379          regular expressions".
1381          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1382          have it.
1384          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1385          "configure" and the latter not, in order to fix a problem somebody had
1386          with compiling the Arg class on HP-UX.
1388          (e) Improve the error-handling of the C++ wrapper a little bit.
1390          (f) New tests for checking recursion limiting.
1392     8. The pcre_memmove() function, which is used only if the environment does not
1393        have a standard memmove() function (and is therefore rarely compiled),
1394        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1395        returning a result (though PCRE never actually uses the result).
1397     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1398        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1399        returned instead of calling malloc() with an overflowing number that would
1400        most likely cause subsequent chaos.
1402    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1404    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1405        with this option is matched, the nmatch and pmatch options of regexec() are
1406        ignored.
1408    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1409        provided in case anyone wants to the the POSIX interface with UTF-8
1410        strings.
1412    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1413        C++ linking (needed for some HP-UX environments).
1415    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1416        (unused parameter) and in the pcre_printint() function (omitted "default"
1417        switch label when the default is to do nothing).
1419    15. Added some code to make it possible, when PCRE is compiled as a C++
1420        library, to replace subject pointers for pcre_exec() with a smart pointer
1421        class, thus making it possible to process discontinuous strings.
1423    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1424        much the same function. They were added by different people who were trying
1425        to make PCRE easy to compile on non-Unix systems. It has been suggested
1426        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1427        for compiling on Windows systems. I have therefore replaced it with
1428        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1429        defaults to "extern" for C or "extern C" for C++, which works fine on
1430        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1431        SCOPE with something explicit in config.h. In addition:
1433        (a) pcreposix.h still had just "extern" instead of either of these macros;
1434            I have replaced it with PCRE_DATA_SCOPE.
1436        (b) Functions such as _pcre_xclass(), which are internal to the library,
1437            but external in the C sense, all had PCRE_EXPORT in their definitions.
1438            This is apparently wrong for the Windows case, so I have removed it.
1439            (It makes no difference on Unix-like systems.)
1441    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1442        of recursive calls to match(). This is different to MATCH_LIMIT because
1443        that limits the total number of calls to match(), not all of which increase
1444        the depth of recursion. Limiting the recursion depth limits the amount of
1445        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1446        when PCRE is compiled, and changed at run time. A patch from Google adds
1447        this functionality to the C++ interface.
1449    18. Changes to the handling of Unicode character properties:
1451        (a) Updated the table to Unicode 4.1.0.
1453        (b) Recognize characters that are not in the table as "Cn" (undefined).
1455        (c) I revised the way the table is implemented to a much improved format
1456            which includes recognition of ranges. It now supports the ranges that
1457            are defined in UnicodeData.txt, and it also amalgamates other
1458            characters into ranges. This has reduced the number of entries in the
1459            table from around 16,000 to around 3,000, thus reducing its size
1460            considerably. I realized I did not need to use a tree structure after
1461            all - a binary chop search is just as efficient. Having reduced the
1462            number of entries, I extended their size from 6 bytes to 8 bytes to
1463            allow for more data.
1465        (d) Added support for Unicode script names via properties such as \p{Han}.
1467    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1468        matching that character.
1470    20. When matching a repeated Unicode property with a minimum greater than zero,
1471        (for example \pL{2,}), PCRE could look past the end of the subject if it
1472        reached it while seeking the minimum number of characters. This could
1473        happen only if some of the characters were more than one byte long, because
1474        there is a check for at least the minimum number of bytes.
1476    21. Refactored the implementation of \p and \P so as to be more general, to
1477        allow for more different types of property in future. This has changed the
1478        compiled form incompatibly. Anybody with saved compiled patterns that use
1479        \p or \P will have to recompile them.
1481    22. Added "Any" and "L&" to the supported property types.
1483    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1484        but give a compile time error if the value is greater than 0xff.
1486    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1487        accidentally not being installed or uninstalled.
1489    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1490        made were to insert the current release number. This seemed silly, because
1491        it made things harder for people building PCRE on systems that don't run
1492        "configure". I have turned pcre.h into a distributed file, no longer built
1493        by "configure", with the version identification directly included. There is
1494        no longer a pcre.h.in file.
1496        However, this change necessitated a change to the pcre-config script as
1497        well. It is built from pcre-config.in, and one of the substitutions was the
1498        release number. I have updated configure.ac so that ./configure now finds
1499        the release number by grepping pcre.h.
1501    26. Added the ability to run the tests under valgrind.
1504    Version 6.4 05-Sep-05
1505    ---------------------
1507     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1508        "--" to be printed when multiple files were scanned, even when none of the
1509        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1510        consider it to be a bug, and have restored the previous behaviour.
1512     2. A couple of code tidies to get rid of compiler warnings.
1514     3. The pcretest program used to cheat by referring to symbols in the library
1515        whose names begin with _pcre_. These are internal symbols that are not
1516        really supposed to be visible externally, and in some environments it is
1517        possible to suppress them. The cheating is now confined to including
1518        certain files from the library's source, which is a bit cleaner.
1520     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1521        file's purpose clearer.
1523     5. Reorganized pcre_ucp_findchar().
1526    Version 6.3 15-Aug-05
1527    ---------------------
1529     1. The file libpcre.pc.in did not have general read permission in the tarball.
1531     2. There were some problems when building without C++ support:
1533        (a) If C++ support was not built, "make install" and "make test" still
1534            tried to test it.
1536        (b) There were problems when the value of CXX was explicitly set. Some
1537            changes have been made to try to fix these, and ...
1539        (c) --disable-cpp can now be used to explicitly disable C++ support.
1541        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1542            backslash in a target when C++ was disabled. This confuses some
1543            versions of "make", apparently. Using an intermediate variable solves
1544            this. (Same for CPP_LOBJ.)
1546     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1547        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1548        necessary on certain architectures.
1550     4. Added a setting of -export-symbols-regex to the link command to remove
1551        those symbols that are exported in the C sense, but actually are local
1552        within the library, and not documented. Their names all begin with
1553        "_pcre_". This is not a perfect job, because (a) we have to except some
1554        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1555        available (and never for static libraries). I have made a note to try to
1556        find a way round (a) in the future.
1559    Version 6.2 01-Aug-05
1560    ---------------------
1562     1. There was no test for integer overflow of quantifier values. A construction
1563        such as {1111111111111111} would give undefined results. What is worse, if
1564        a minimum quantifier for a parenthesized subpattern overflowed and became
1565        negative, the calculation of the memory size went wrong. This could have
1566        led to memory overwriting.
1568     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1570     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1571        operating environments where this matters.
1573     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1574        PCRE options from within the C++ wrapper.
1576     5. Named capturing subpatterns were not being correctly counted when a pattern
1577        was compiled. This caused two problems: (a) If there were more than 100
1578        such subpatterns, the calculation of the memory needed for the whole
1579        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1580        back references of the form \12, where the number was greater than 9, were
1581        not recognized as back references, even though there were sufficient
1582        previous subpatterns.
1584     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1585        versions of gcc, e.g. 2.95.4.
1588    Version 6.1 21-Jun-05
1589    ---------------------
1591     1. There was one reference to the variable "posix" in pcretest.c that was not
1592        surrounded by "#if !defined NOPOSIX".
1594     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1595        the cross-check on the old pcre_info() function, for the benefit of the
1596        cut-down version of PCRE that is currently imported into Exim.
1598     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1599        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1600        patterns that start (?i) but I don't think that matters. The use of (?i) is
1601        just an example; this all applies to the other options as well.
1603     4. Since libtool seems to echo the compile commands it is issuing, the output
1604        from "make" can be reduced a bit by putting "@" in front of each libtool
1605        compile command.
1607     5. Patch from the folks at Google for configure.in to be a bit more thorough
1608        in checking for a suitable C++ installation before trying to compile the
1609        C++ stuff. This should fix a reported problem when a compiler was present,
1610        but no suitable headers.
1612     6. The man pages all had just "PCRE" as their title. I have changed them to
1613        be the relevant file name. I have also arranged that these names are
1614        retained in the file doc/pcre.txt, which is a concatenation in text format
1615        of all the man pages except the little individual ones for each function.
1617     7. The NON-UNIX-USE file had not been updated for the different set of source
1618        files that come with release 6. I also added a few comments about the C++
1619        wrapper.
1622    Version 6.0 07-Jun-05
1623    ---------------------
1625     1. Some minor internal re-organization to help with my DFA experiments.
1627     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1628        didn't matter for the library itself when fully configured, but did matter
1629        when compiling without UCP support, or within Exim, where the ucp files are
1630        not imported.
1632     3. Refactoring of the library code to split up the various functions into
1633        different source modules. The addition of the new DFA matching code (see
1634        below) to a single monolithic source would have made it really too
1635        unwieldy, quite apart from causing all the code to be include in a
1636        statically linked application, when only some functions are used. This is
1637        relevant even without the DFA addition now that patterns can be compiled in
1638        one application and matched in another.
1640        The downside of splitting up is that there have to be some external
1641        functions and data tables that are used internally in different modules of
1642        the library but which are not part of the API. These have all had their
1643        names changed to start with "_pcre_" so that they are unlikely to clash
1644        with other external names.
1646     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1647        a different (DFA) algorithm. Although it is slower than the original
1648        function, it does have some advantages for certain types of matching
1649        problem.
1651     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1652        including restarting after a partial match.
1654     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1655        defined when compiling for Windows was sent to me. I have put it into the
1656        code, though I have no means of testing or verifying it.
1658     7. Added the pcre_refcount() auxiliary function.
1660     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1661        match before or at the first newline in the subject string. In pcretest,
1662        the /f option on a pattern can be used to set this.
1664     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1665        would behave wrongly. This has been present in PCRE since release 4.0.
1667    10. A number of changes to the pcregrep command:
1669        (a) Refactored how -x works; insert ^(...)$ instead of setting
1670            PCRE_ANCHORED and checking the length, in preparation for adding
1671            something similar for -w.
1673        (b) Added the -w (match as a word) option.
1675        (c) Refactored the way lines are read and buffered so as to have more
1676            than one at a time available.
1678        (d) Implemented a pcregrep test script.
1680        (e) Added the -M (multiline match) option. This allows patterns to match
1681            over several lines of the subject. The buffering ensures that at least
1682            8K, or the rest of the document (whichever is the shorter) is available
1683            for matching (and similarly the previous 8K for lookbehind assertions).
1685        (f) Changed the --help output so that it now says
1687              -w, --word-regex(p)
1689            instead of two lines, one with "regex" and the other with "regexp"
1690            because that confused at least one person since the short forms are the
1691            same. (This required a bit of code, as the output is generated
1692            automatically from a table. It wasn't just a text change.)
1694        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1695            option but starts with a hyphen. Could be a pattern or a path name
1696            starting with a hyphen, for instance.
1698        (h) "-" can be given as a file name to represent stdin.
1700        (i) When file names are being printed, "(standard input)" is used for
1701            the standard input, for compatibility with GNU grep. Previously
1702            "<stdin>" was used.
1704        (j) The option --label=xxx can be used to supply a name to be used for
1705            stdin when file names are being printed. There is no short form.
1707        (k) Re-factored the options decoding logic because we are going to add
1708            two more options that take data. Such options can now be given in four
1709            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1711        (l) Added the -A, -B, and -C options for requesting that lines of context
1712            around matches be printed.
1714        (m) Added the -L option to print the names of files that do not contain
1715            any matching lines, that is, the complement of -l.
1717        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1718            continue to scan other files.
1720        (o) The -s option was incorrectly implemented. For compatibility with other
1721            greps, it now suppresses the error message for a non-existent or non-
1722            accessible file (but not the return code). There is a new option called
1723            -q that suppresses the output of matching lines, which was what -s was
1724            previously doing.
1726        (p) Added --include and --exclude options to specify files for inclusion
1727            and exclusion when recursing.
1729    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1730        Hopefully, it now does.
1732    12. Missing cast in pcre_study().
1734    13. Added an "uninstall" target to the makefile.
1736    14. Replaced "extern" in the function prototypes in Makefile.in with
1737        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1738        world, but is set differently for Windows.
1740    15. Added a second compiling function called pcre_compile2(). The only
1741        difference is that it has an extra argument, which is a pointer to an
1742        integer error code. When there is a compile-time failure, this is set
1743        non-zero, in addition to the error test pointer being set to point to an
1744        error message. The new argument may be NULL if no error number is required
1745        (but then you may as well call pcre_compile(), which is now just a
1746        wrapper). This facility is provided because some applications need a
1747        numeric error indication, but it has also enabled me to tidy up the way
1748        compile-time errors are handled in the POSIX wrapper.
1750    16. Added VPATH=.libs to the makefile; this should help when building with one
1751        prefix path and installing with another. (Or so I'm told by someone who
1752        knows more about this stuff than I do.)
1754    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1755        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1756        match everything, including newlines. This is not POSIX-compatible, but
1757        somebody wanted the feature. From pcretest it can be activated by using
1758        both the P and the s flags.
1760    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1762    19. libpcre.pc was being incorrectly installed as executable.
1764    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1765        it now also looks for '\r' so that it will work unmodified on Windows.
1767    21. Added Google's contributed C++ wrapper to the distribution.
1769    22. Added some untidy missing memory free() calls in pcretest, to keep
1770        Electric Fence happy when testing.
1774    Version 5.0 13-Sep-04
1775    ---------------------
1777     1. Internal change: literal characters are no longer packed up into items
1778        containing multiple characters in a single byte-string. Each character
1779        is now matched using a separate opcode. However, there may be more than one
1780        byte in the character in UTF-8 mode.
1782     2. The pcre_callout_block structure has two new fields: pattern_position and
1783        next_item_length. These contain the offset in the pattern to the next match
1784        item, and its length, respectively.
1786     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1787        insertion of callouts before each pattern item. Added the /C option to
1788        pcretest to make use of this.
1790     4. On the advice of a Windows user, the lines
1792          #if defined(_WIN32) || defined(WIN32)
1793          _setmode( _fileno( stdout ), 0x8000 );
1794          #endif  /* defined(_WIN32) || defined(WIN32) */
1796        have been added to the source of pcretest. This apparently does useful
1797        magic in relation to line terminators.
1799     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1800        for the benefit of those environments where the "b" makes a difference.
1802     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1803        to know about it. I have put a hack into configure.in that adds in code
1804        to set GCC=yes if CC=icc. This seems to end up at a point in the
1805        generated configure script that is early enough to affect the setting of
1806        compiler options, which is what is needed, but I have no means of testing
1807        whether it really works. (The user who reported this had patched the
1808        generated configure script, which of course I cannot do.)
1810        LATER: After change 22 below (new libtool files), the configure script
1811        seems to know about icc (and also ecc). Therefore, I have commented out
1812        this hack in configure.in.
1814     7. Added support for pkg-config (2 patches were sent in).
1816     8. Negated POSIX character classes that used a combination of internal tables
1817        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1818        [[:^ascii]]. Typically, they would match almost any characters. The other
1819        POSIX classes were not broken in this way.
1821     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1822        to find the match, as PCRE was deluded into thinking that the match had to
1823        start at the start point or following a newline. The same bug applied to
1824        patterns with negative forward assertions or any backward assertions
1825        preceding ".*" at the start, unless the pattern required a fixed first
1826        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1828    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1829        starting at the last subject character, bytes beyond the end of the subject
1830        string were read.
1832    11. Renamed the variable "class" as "classbits" to make life easier for C++
1833        users. (Previously there was a macro definition, but it apparently wasn't
1834        enough.)
1836    12. Added the new field "tables" to the extra data so that tables can be passed
1837        in at exec time, or the internal tables can be re-selected. This allows
1838        a compiled regex to be saved and re-used at a later time by a different
1839        program that might have everything at different addresses.
1841    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1842        -R library as well as a -L library.
1844    14. The debugging options of pcretest (-d on the command line or D on a
1845        pattern) showed incorrect output for anything following an extended class
1846        that contained multibyte characters and which was followed by a quantifier.
1848    15. Added optional support for general category Unicode character properties
1849        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1850        support. It adds about 90K to the size of the library. The meanings of the
1851        inbuilt class escapes such as \d and \s have NOT been changed.
1853    16. Updated pcredemo.c to include calls to free() to release the memory for the
1854        compiled pattern.
1856    17. The generated file chartables.c was being created in the source directory
1857        instead of in the building directory. This caused the build to fail if the
1858        source directory was different from the building directory, and was
1859        read-only.
1861    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1862        file. No doubt somebody will tell me if they don't make sense... Also added
1863        Dan Mooney's comments about building on OpenVMS.
1865    19. Added support for partial matching via the PCRE_PARTIAL option for
1866        pcre_exec() and the \P data escape in pcretest.
1868    20. Extended pcretest with 3 new pattern features:
1870        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1871              write the compiled pattern to the file whose name is "rest-of-line".
1872              This is a straight binary dump of the data, with the saved pointer to
1873              the character tables forced to be NULL. The study data, if any, is
1874              written too. After writing, pcretest reads a new pattern.
1876        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1877              compiled pattern from the given file. There must not be any
1878              occurrences of "<" in the file name (pretty unlikely); if there are,
1879              pcretest will instead treat the initial "<" as a pattern delimiter.
1880              After reading in the pattern, pcretest goes on to read data lines as
1881              usual.
1883        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1884              and 16-bit fields in a compiled pattern, to simulate a pattern that
1885              was compiled on a host of opposite endianness.
1887    21. The pcre-exec() function can now cope with patterns that were compiled on
1888        hosts of opposite endianness, with this restriction:
1890          As for any compiled expression that is saved and used later, the tables
1891          pointer field cannot be preserved; the extra_data field in the arguments
1892          to pcre_exec() should be used to pass in a tables address if a value
1893          other than the default internal tables were used at compile time.
1895    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1896        now diagnosed as an error. Previously, most of the time, a negative number
1897        would have been treated as zero, but if in addition "ovector" was passed as
1898        NULL, a crash could occur.
1900    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1901        new versions from the libtool 1.5 distribution (the last one is a copy of
1902        a file called libtool.m4). This seems to have fixed the need to patch
1903        "configure" to support Darwin 1.3 (which I used to do). However, I still
1904        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1905        workstation).
1907    24. Changed the PCRE licence to be the more standard "BSD" licence.
1910    Version 4.5 01-Dec-03
1911    ---------------------
1913     1. There has been some re-arrangement of the code for the match() function so
1914        that it can be compiled in a version that does not call itself recursively.
1915        Instead, it keeps those local variables that need separate instances for
1916        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1917        needs to "recurse". Keeping track of where control must go is done by means
1918        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1919        hide most of the details from the main code, and operates only if
1920        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1921        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1922        operating.
1924        To make it easier for callers to provide specially tailored get/free
1925        functions for this usage, two new functions, pcre_stack_malloc, and
1926        pcre_stack_free, are used. They are always called in strict stacking order,
1927        and the size of block requested is always the same.
1929        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1930        PCRE has been compiled to use the stack or the heap for recursion. The
1931        -C option of pcretest uses this to show which version is compiled.
1933        A new data escape \S, is added to pcretest; it causes the amounts of store
1934        obtained and freed by both kinds of malloc/free at match time to be added
1935        to the output.
1937     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1938        what's available on my current Linux desktop machine.
1940     3. When matching a UTF-8 string, the test for a valid string at the start has
1941        been extended. If start_offset is not zero, PCRE now checks that it points
1942        to a byte that is the start of a UTF-8 character. If not, it returns
1943        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1944        this is necessary because there may be backward assertions in the pattern.
1945        When matching the same subject several times, it may save resources to use
1946        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1948     4. The code for checking the validity of UTF-8 strings has been tightened so
1949        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1950        containing "overlong sequences".
1952     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1953        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1954        should have been "&", but it just so happened that all the cases this let
1955        through by mistake were picked up later in the function.
1957     6. I had used a variable called "isblank" - this is a C99 function, causing
1958        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1960     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1961        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1962        so the version is shown; (c) stop "make test" echoing "./RunTest".
1964     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1966     9. The prototype for memmove() for systems that don't have it was using
1967        size_t, but the inclusion of the header that defines size_t was later. I've
1968        moved the #includes for the C headers earlier to avoid this.
1970    10. Added some adjustments to the code to make it easier to compiler on certain
1971        special systems:
1973          (a) Some "const" qualifiers were missing.
1974          (b) Added the macro EXPORT before all exported functions; by default this
1975              is defined to be empty.
1976          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1977              that it reads its output file name as an argument instead of writing
1978              to the standard output and assuming this can be redirected.
1980    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1981        class containing characters with values greater than 255, PCRE compilation
1982        went into a loop.
1984    12. A recursive reference to a subpattern that was within another subpattern
1985        that had a minimum quantifier of zero caused PCRE to crash. For example,
1986        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1987        recursion. If the recursively-called subpattern itself had a zero repeat,
1988        that was OK.
1990    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1991        buffer into which it was copied (for escape processing) was still set at
1992        1024, so long lines caused crashes.
1994    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1995        "internal error: code overflow...". This applied to any character class
1996        that was followed by a possessive quantifier.
1998    15. Modified the Makefile to add libpcre.la as a prerequisite for
1999        libpcreposix.la because I was told this is needed for a parallel build to
2000        work.
2002    16. If a pattern that contained .* following optional items at the start was
2003        studied, the wrong optimizing data was generated, leading to matching
2004        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
2005        matching string must start with a or b or c. The correct conclusion for
2006        this pattern is that a match can start with any character.
2009    Version 4.4 13-Aug-03
2010    ---------------------
2012     1. In UTF-8 mode, a character class containing characters with values between
2013        127 and 255 was not handled correctly if the compiled pattern was studied.
2014        In fixing this, I have also improved the studying algorithm for such
2015        classes (slightly).
2017     2. Three internal functions had redundant arguments passed to them. Removal
2018        might give a very teeny performance improvement.
2020     3. Documentation bug: the value of the capture_top field in a callout is *one
2021        more than* the number of the hightest numbered captured substring.
2023     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
2024        in incorrectly linking with a previously installed version. They now link
2025        explicitly with libpcre.la.
2027     5. configure.in no longer needs to recognize Cygwin specially.
2029     6. A problem in pcre.in for Windows platforms is fixed.
2031     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
2032        pcretest, it used to include the size of the study block as part of its
2033        output. Unfortunately, the structure contains a field that has a different
2034        size on different hardware architectures. This meant that the tests that
2035        showed this size failed. As the block is currently always of a fixed size,
2036        this information isn't actually particularly useful in pcretest output, so
2037        I have just removed it.
2039     8. Three pre-processor statements accidentally did not start in column 1.
2040        Sadly, there are *still* compilers around that complain, even though
2041        standard C has not required this for well over a decade. Sigh.
2043     9. In pcretest, the code for checking callouts passed small integers in the
2044        callout_data field, which is a void * field. However, some picky compilers
2045        complained about the casts involved for this on 64-bit systems. Now
2046        pcretest passes the address of the small integer instead, which should get
2047        rid of the warnings.
2049    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
2050        both compile and run time, and gives an error if an invalid UTF-8 sequence
2051        is found. There is a option for disabling this check in cases where the
2052        string is known to be correct and/or the maximum performance is wanted.
2054    11. In response to a bug report, I changed one line in Makefile.in from
2056            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
2057        to
2058            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
2060        to look similar to other lines, but I have no way of telling whether this
2061        is the right thing to do, as I do not use Windows. No doubt I'll get told
2062        if it's wrong...
2065    Version 4.3 21-May-03
2066    ---------------------
2068    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
2069       Makefile.
2071    2. Some refactoring to improve the quality of the code:
2073       (i)   The utf8_table... variables are now declared "const".
2075       (ii)  The code for \cx, which used the "case flipping" table to upper case
2076             lower case letters, now just substracts 32. This is ASCII-specific,
2077             but the whole concept of \cx is ASCII-specific, so it seems
2078             reasonable.
2080       (iii) PCRE was using its character types table to recognize decimal and
2081             hexadecimal digits in the pattern. This is silly, because it handles
2082             only 0-9, a-f, and A-F, but the character types table is locale-
2083             specific, which means strange things might happen. A private
2084             table is now used for this - though it costs 256 bytes, a table is
2085             much faster than multiple explicit tests. Of course, the standard
2086             character types table is still used for matching digits in subject
2087             strings against \d.
2089       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
2090             ending in _t are). So I've renamed it as ESC_tee.
2092    3. The first argument for regexec() in the POSIX wrapper should have been
2093       defined as "const".
2095    4. Changed pcretest to use malloc() for its buffers so that they can be
2096       Electric Fenced for debugging.
2098    5. There were several places in the code where, in UTF-8 mode, PCRE would try
2099       to read one or more bytes before the start of the subject string. Often this
2100       had no effect on PCRE's behaviour, but in some circumstances it could
2101       provoke a segmentation fault.
2103    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
2104       to try to read one or more bytes before the start of the subject string.
2106    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
2107       UTF-8 support could misbehave in various ways if the subject string
2108       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
2109       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
2110       back over UTF-8 characters.)
2113    Version 4.2 14-Apr-03
2114    ---------------------
2116    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
2118    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
2119         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
2120         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
2121         [WIN_PREFIX]: new variable, "cyg" for Cygwin
2122         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
2123           and BUILD_EXEEXT
2124         Note: automatic setting of the BUILD variables is not yet working
2125         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
2126           compile-time but not at link-time
2127         [LINK]: use for linking executables only
2128         make different versions for Windows and non-Windows
2129         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
2130           libraries
2131         [LINK_FOR_BUILD]: new variable
2132         [OBJEXT]: use throughout
2133         [EXEEXT]: use throughout
2134         <winshared>: new target
2135         <wininstall>: new target
2136         <dftables.o>: use native compiler
2137         <dftables>: use native linker
2138         <install>: handle Windows platform correctly
2139         <clean>: ditto
2140         <check>: ditto
2141         copy DLL to top builddir before testing
2143       As part of these changes, -no-undefined was removed again. This was reported
2144       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
2145       in any case.
2147    3. Some tidies to get rid of compiler warnings:
2149       . In the match_data structure, match_limit was an unsigned long int, whereas
2150         match_call_count was an int. I've made them both unsigned long ints.
2152       . In pcretest the fact that a const uschar * doesn't automatically cast to
2153         a void * provoked a warning.
2155       . Turning on some more compiler warnings threw up some "shadow" variables
2156         and a few more missing casts.
2158    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
2159       option, a class that contained a single character with a value between 128
2160       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
2162    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
2163       option, a class that contained several characters, but with at least one
2164       whose value was between 128 and 255 caused PCRE to crash.
2167    Version 4.1 12-Mar-03
2168    ---------------------
2170    1. Compiling with gcc -pedantic found a couple of places where casts were
2171    needed, and a string in dftables.c that was longer than standard compilers are
2172    required to support.
2174    2. Compiling with Sun's compiler found a few more places where the code could
2175    be tidied up in order to avoid warnings.
2177    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
2178    first of these names is deprecated in the latest Autoconf in favour of the name
2179    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
2180    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
2181    analogy I have changed it to CFLAGS_FOR_BUILD.
2183    4. Added -no-undefined to the linking command in the Makefile, because this is
2184    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2185    linking step for the pcreposix library.
2187    5. PCRE was failing to diagnose the case of two named groups with the same
2188    name.
2190    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2191    literal character that is needed in the subject for a match, and scans along to
2192    ensure that it is present before embarking on the full matching process. This
2193    saves time in cases of nested unlimited repeats that are never going to match.
2194    Problem: the scan can take a lot of time if the subject is very long (e.g.
2195    megabytes), thus penalizing straightforward matches. It is now done only if the
2196    amount of subject to be scanned is less than 1000 bytes.
2198    7. A lesser problem with the same optimization is that it was recording the
2199    first character of an anchored pattern as "needed", thus provoking a search
2200    right along the subject, even when the first match of the pattern was going to
2201    fail. The "needed" character is now not set for anchored patterns, unless it
2202    follows something in the pattern that is of non-fixed length. Thus, it still
2203    fulfils its original purpose of finding quick non-matches in cases of nested
2204    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2207    Version 4.0 17-Feb-03
2208    ---------------------
2210    1. If a comment in an extended regex that started immediately after a meta-item
2211    extended to the end of string, PCRE compiled incorrect data. This could lead to
2212    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2214    2. Moved to autoconf 2.53 and libtool 1.4.2.
2216    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2217    the special perltest8 script is no longer needed - all the tests can be run
2218    from a single perltest script.
2220    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2221    by \s. It has now been removed in PCRE. This means it isn't recognized as
2222    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2223    class [:space:] *does* include VT, thereby creating a mess.
2225    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2226    space and tab.
2228    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2229    its new features into the main test script, reducing the number of scripts.
2231    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2232    were backward compatible, and made the (?i) apply to the whole pattern, as if
2233    /i were given. Now it behaves more logically, and applies the option setting
2234    only to what follows. PCRE has been changed to follow suit. However, if it
2235    finds options settings right at the start of the pattern, it extracts them into
2236    the global options, as before. Thus, they show up in the info data.
2238    8. Added support for the \Q...\E escape sequence. Characters in between are
2239    treated as literals. This is slightly different from Perl in that $ and @ are
2240    also handled as literals inside the quotes. In Perl, they will cause variable
2241    interpolation. Note the following examples:
2243        Pattern            PCRE matches      Perl matches
2245        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2246        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2247        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2249    For compatibility with Perl, \Q...\E sequences are recognized inside character
2250    classes as well as outside them.
2252    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2253    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2254    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2255    signed/unsigned warnings.
2257    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2258    option for pcretest, so I've replaced it by a simple function that does just
2259    that job.
2261    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2262    "pcregrep -".
2264    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2265    Java package. This provides some syntactic sugar for simple cases of what my
2266    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2267    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2268    item, you can use this simplified notation. Note that only makes sense with
2269    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2270    greediness, whatever the setting of the PCRE_UNGREEDY option.
2272    13. A change of greediness default within a pattern was not taking effect at
2273    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2274    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2275    was abstracted outside.
2277    14. PCRE now supports the \G assertion. It is true when the current matching
2278    position is at the start point of the match. This differs from \A when the
2279    starting offset is non-zero. Used with the /g option of pcretest (or similar
2280    code), it works in the same way as it does for Perl's /g option. If all
2281    alternatives of a regex begin with \G, the expression is anchored to the start
2282    match position, and the "anchored" flag is set in the compiled expression.
2284    15. Some bugs concerning the handling of certain option changes within patterns
2285    have been fixed. These applied to options other than (?ims). For example,
2286    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2287    been the other way round. Some of this was related to change 7 above.
2289    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2290    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2291    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2292    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2294    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2295    mode. Unlike ".", it always matches newline, whatever the setting of
2296    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2297    assertions. Perl allows it, but it doesn't (in general) work because it can't
2298    calculate the length of the lookbehind. At least, that's the case for Perl
2299    5.8.0 - I've been told they are going to document that it doesn't work in
2300    future.
2302    18. Added an error diagnosis for escapes that PCRE does not support: these are
2303    \L, \l, \N, \P, \p, \U, \u, and \X.
2305    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2306    reading past the end of the pattern in cases such as /[abcd/.
2308    20. PCRE was getting more memory than necessary for patterns with classes that
2309    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2311    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2312    compiling PCRE for use with Virtual Pascal.
2314    22. Small fix to the Makefile to make it work properly if the build is done
2315    outside the source tree.
2317    23. Added a new extension: a condition to go with recursion. If a conditional
2318    subpattern starts with (?(R) the "true" branch is used if recursion has
2319    happened, whereas the "false" branch is used only at the top level.
2321    24. When there was a very long string of literal characters (over 255 bytes
2322    without UTF support, over 250 bytes with UTF support), the computation of how
2323    much memory was required could be incorrect, leading to segfaults or other
2324    strange effects.
2326    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2327    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2328    there was a subsequent back reference to those brackets. This meant that, for
2329    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2330    possible to check for precisely this case. All we can do is abandon the
2331    optimization if .* occurs inside capturing brackets when there are any back
2332    references whatsoever. (See below for a better fix that came later.)
2334    26. The handling of the optimization for finding the first character of a
2335    non-anchored pattern, and for finding a character that is required later in the
2336    match were failing in some cases. This didn't break the matching; it just
2337    failed to optimize when it could. The way this is done has been re-implemented.
2339    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2341    28. Added a new feature that provides some of the functionality that Perl
2342    provides with (?{...}). The facility is termed a "callout". The way it is done
2343    in PCRE is for the caller to provide an optional function, by setting
2344    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2345    global variable. By default it is unset, which disables all calling out. To get
2346    the function called, the regex must include (?C) at appropriate points. This
2347    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2348    This provides a means of identifying different callout points. When PCRE
2349    reaches such a point in the regex, if pcre_callout has been set, the external
2350    function is called. It is provided with data in a structure called
2351    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2352    matching continues; if it returns a non-zero value, the match at the current
2353    point fails. However, backtracking will occur if possible. [This was changed
2354    later and other features added - see item 49 below.]
2356    29. pcretest is upgraded to test the callout functionality. It provides a
2357    callout function that displays information. By default, it shows the start of
2358    the match and the current position in the text. There are some new data escapes
2359    to vary what happens:
2361        \C+         in addition, show current contents of captured substrings
2362        \C-         do not supply a callout function
2363        \C!n        return 1 when callout number n is reached
2364        \C!n!m      return 1 when callout number n is reached for the mth time
2366    30. If pcregrep was called with the -l option and just a single file name, it
2367    output "<stdin>" if a match was found, instead of the file name.
2369    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2370    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2371    pcre_exec(). This saves a malloc/free per call. The default value of
2372    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2373    when configuring.
2375    32. The default maximum size of a compiled pattern is 64K. There have been a
2376    few cases of people hitting this limit. The code now uses macros to handle the
2377    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2378    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2379    configuring. Tests 2 and 5 work only with 2-byte links because they output
2380    debugging information about compiled patterns.
2382    33. Internal code re-arrangements:
2384    (a) Moved the debugging function for printing out a compiled regex into
2385        its own source file (printint.c) and used #include to pull it into
2386        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2387        separate copies.
2389    (b) Defined the list of op-code names for debugging as a macro in
2390        internal.h so that it is next to the definition of the opcodes.
2392    (c) Defined a table of op-code lengths for simpler skipping along compiled
2393        code. This is again a macro in internal.h so that it is next to the
2394        definition of the opcodes.
2396    34. Added support for recursive calls to individual subpatterns, along the
2397    lines of Robin Houston's patch (but implemented somewhat differently).
2399    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2400    allow it to read and process whole directories in Win32. This code was
2401    contributed by Lionel Fourquaux; it has not been tested by me.
2403    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2404    used to name a group. Names consist of alphanumerics and underscores, and must
2405    be unique. Back references use the syntax (?P=name) and recursive calls use
2406    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2407    numbers. The function pcre_fullinfo() can be used after compilation to extract
2408    a name/number map. There are three relevant calls:
2410      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2411      PCRE_INFO_NAMECOUNT            yields the number of entries
2412      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2414    The map is a vector of fixed-size entries. The size of each entry depends on
2415    the length of the longest name used. The first two bytes of each entry are the
2416    group number, most significant byte first. There follows the corresponding
2417    name, zero terminated. The names are in alphabetical order.
2419    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2420    case instead of 255. Making it the same both with and without UTF-8 support
2421    means that the same test output works with both.
2423    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2424    calling malloc() with a zero argument.
2426    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2427    optimization. I've improved things by keeping a bitmap of backreferences with
2428    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2429    fact referenced, the optimization can be applied. It is unlikely that a
2430    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2431    the match to follow \n) will appear inside brackets with a number greater than
2432    31, but if it does, any back reference > 31 suppresses the optimization.
2434    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2435    of disabling numbered capturing parentheses. Any opening parenthesis that is
2436    not followed by ? behaves as if it were followed by ?: but named parentheses
2437    can still be used for capturing (and they will acquire numbers in the usual
2438    way).
2440    41. Redesigned the return codes from the match() function into yes/no/error so
2441    that errors can be passed back from deep inside the nested calls. A malloc
2442    failure while inside a recursive subpattern call now causes the
2443    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2445    42. It is now possible to set a limit on the number of times the match()
2446    function is called in a call to pcre_exec(). This facility makes it possible to
2447    limit the amount of recursion and backtracking, though not in a directly
2448    obvious way, because the match() function is used in a number of different
2449    circumstances. The count starts from zero for each position in the subject
2450    string (for non-anchored patterns). The default limit is, for compatibility, a
2451    large number, namely 10 000 000. You can change this in two ways:
2453    (a) When configuring PCRE before making, you can use --with-match-limit=n
2454        to set a default value for the compiled library.
2456    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2457        a different value is set. See 45 below.
2459    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2461    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2462    of things that can be changed at compile time. The first argument specifies
2463    what is wanted and the second points to where the information is to be placed.
2464    The current list of available information is:
2466      PCRE_CONFIG_UTF8
2468    The output is an integer that is set to one if UTF-8 support is available;
2469    otherwise it is set to zero.
2473    The output is an integer that it set to the value of the code that is used for
2474    newline. It is either LF (10) or CR (13).
2478    The output is an integer that contains the number of bytes used for internal
2479    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2483    The output is an integer that contains the threshold above which the POSIX
2484    interface uses malloc() for output vectors. See item 31 above.
2488    The output is an unsigned integer that contains the default limit of the number
2489    of match() calls in a pcre_exec() execution. See 42 above.
2491    44. pcretest has been upgraded by the addition of the -C option. This causes it
2492    to extract all the available output from the new pcre_config() function, and to
2493    output it. The program then exits immediately.
2495    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2496    order to support additional features. One way would have been to define
2497    pcre_exec2() (for example) with extra arguments, but this would not have been
2498    extensible, and would also have required all calls to the original function to
2499    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2500    is used for passing in "extra" data from pcre_study().
2502    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2503    contains the following fields:
2505      flags         a bitmap indicating which of the following fields are set
2506      study_data    opaque data from pcre_study()
2507      match_limit   a way of specifying a limit on match() calls for a specific
2508                      call to pcre_exec()
2509      callout_data  data for callouts (see 49 below)
2511    The flag bits are also defined in pcre.h, and are
2517    The pcre_study() function now returns one of these new pcre_extra blocks, with
2518    the actual study data pointed to by the study_data field, and the
2519    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2520    before. That is, this change is entirely upwards-compatible and requires no
2521    change to existing code.
2523    If you want to pass in additional data to pcre_exec(), you can either place it
2524    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2525    block.
2527    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2528    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2529    times with different match limits, until it finds the minimum value needed for
2530    pcre_exec() to complete. The value is then output. This can be instructive; for
2531    most simple matches the number is quite small, but for pathological cases it
2532    gets very large very quickly.
2534    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2535    returns the size of the data block pointed to by the study_data field in a
2536    pcre_extra block, that is, the value that was passed as the argument to
2537    pcre_malloc() when PCRE was getting memory in which to place the information
2538    created by pcre_study(). The fourth argument should point to a size_t variable.
2539    pcretest has been extended so that this information is shown after a successful
2540    pcre_study() call when information about the compiled regex is being displayed.
2542    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2543    because what follows is always an absolute path. (Later: it turns out that this
2544    is more than cosmetic for MinGW, because it doesn't like empty path
2545    components.)
2547    49. Some changes have been made to the callout feature (see 28 above):
2549    (i)  A callout function now has three choices for what it returns:
2551           0  =>  success, carry on matching
2552         > 0  =>  failure at this point, but backtrack if possible
2553         < 0  =>  serious error, return this value from pcre_exec()
2555         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2556         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2557         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2558         use by callout functions. It will never be used by PCRE itself.
2560    (ii) The pcre_extra structure (see 45 above) has a void * field called
2561         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2562         pcre_callout_block structure has a field of the same name. The contents of
2563         the field passed in the pcre_extra structure are passed to the callout
2564         function in the corresponding field in the callout block. This makes it
2565         easier to use the same callout-containing regex from multiple threads. For
2566         testing, the pcretest program has a new data escape
2568           \C*n        pass the number n (may be negative) as callout_data
2570         If the callout function in pcretest receives a non-zero value as
2571         callout_data, it returns that value.
2573    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2574    there were some redundant $(CFLAGS) in commands that are now specified as
2575    $(LINK), which already includes $(CFLAGS).
2577    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2578    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2579    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2580    one-byte characters throughout. Note that case-insensitive matching applies
2581    only to characters whose values are less than 256. PCRE doesn't support the
2582    notion of cases for higher-valued characters.
2584    (i)   A character class whose characters are all within 0-255 is handled as
2585          a bit map, and the map is inverted for negative classes. Previously, a
2586          character > 255 always failed to match such a class; however it should
2587          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2589    (ii)  A negated character class with a single character < 255 is coded as
2590          "not this character" (OP_NOT). This wasn't working properly when the test
2591          character was multibyte, either singly or repeated.
2593    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2594          mode, for example: \x{100}{2,3}.
2596    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2597          singly or repeated) now correctly test multibyte characters. However,
2598          PCRE doesn't recognize any characters with values greater than 255 as
2599          digits, spaces, or word characters. Such characters always match \D, \S,
2600          and \W, and never match \d, \s, or \w.
2602    (v)   Classes may now contain characters and character ranges with values
2603          greater than 255. For example: [ab\x{100}-\x{400}].
2605    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2606          PCRE in UTF-8 mode.
2608    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2609    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2610    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2611    value.)
2613    53. The single man page has become too large. I have therefore split it up into
2614    a number of separate man pages. These also give rise to individual HTML pages;
2615    these are now put in a separate directory, and there is an index.html page that
2616    lists them all. Some hyperlinking between the pages has been installed.
2618    54. Added convenience functions for handling named capturing parentheses.
2620    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2621    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2622    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2623    are faulted.
2625    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2626    calling configure. These values are used when compiling the dftables.c program
2627    which is run to generate the source of the default character tables. They
2628    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2629    you will need to set these values.
2631    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2634    Version 3.9 02-Jan-02
2635  ---------------------  ---------------------
2637  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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