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revision 61 by nigel, Sat Feb 24 21:39:58 2007 UTC revision 336 by ph10, Sat Apr 12 15:59:03 2008 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 3.0 02-Jan-02  Version 7.7 05-Mar-08
5    ---------------------
7    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
8        a string to a long long, pretend we don't even have a long long." This is
9        done by checking for the strtoq, strtoll, and _strtoi64 functions.
11    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
12        pre-7.6 versions, which defined a global no_arg variable instead of putting
13        it in the RE class. (See also #8 below.)
15    3.  Remove a line of dead code, identified by coverity and reported by Nuno
16        Lopes.
18    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
20        (1) The include/exclude patterns were being applied to the whole pathnames
21            of files, instead of just to the final components.
23        (2) If there was more than one level of directory, the subdirectories were
24            skipped unless they satisfied the include/exclude conditions. This is
25            inconsistent with GNU grep (and could even be seen as contrary to the
26            pcregrep specification - which I improved to make it absolutely clear).
27            The action now is always to scan all levels of directory, and just
28            apply the include/exclude patterns to regular files.
30    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
31        --exclude_dir in the tests to avoid scanning .svn directories.
33    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
34        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
35        doesn't support NULs in patterns.
37    7.  Added some missing "const"s to declarations of static tables in
38        pcre_compile.c and pcre_dfa_exec.c.
40    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
41        caused by fix #2  above. (Subsequently also a second patch to fix the
42        first patch. And a third patch - this was a messy problem.)
44    9.  Applied Craig's patch to remove the use of push_back().
46    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
47        matching function regexec().
49    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
50        which, however, unlike Perl's \g{...}, are subroutine calls, not back
51        references. PCRE supports relative numbers with this syntax (I don't think
52        Oniguruma does).
54    12. Previously, a group with a zero repeat such as (...){0} was completely
55        omitted from the compiled regex. However, this means that if the group
56        was called as a subroutine from elsewhere in the pattern, things went wrong
57        (an internal error was given). Such groups are now left in the compiled
58        pattern, with a new opcode that causes them to be skipped at execution
59        time.
61    13. Added the PCRE_JAVASCRIPT_COMPAT option. This currently does two things:
62        (a) A lone ] character is dis-allowed (Perl treats it as data).
63        (b) A back reference to an unmatched subpattern matches an empty string
64            (Perl fails the current match path).
67    Version 7.6 28-Jan-08
68    ---------------------
70    1.  A character class containing a very large number of characters with
71        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
72        overflow.
74    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
75        HAVE_LONG_LONG is not defined.
77    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
78        bring them up to date and include new features. This patch includes:
80        - Fixed PH's badly added libz and libbz2 support.
81        - Fixed a problem with static linking.
82        - Added pcredemo. [But later removed - see 7 below.]
83        - Fixed dftables problem and added an option.
84        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
85            HAVE_LONG_LONG.
86        - Added readline support for pcretest.
87        - Added an listing of the option settings after cmake has run.
89    4.  A user submitted a patch to Makefile that makes it easy to create
90        "pcre.dll" under mingw when using Configure/Make. I added stuff to
91        Makefile.am that cause it to include this special target, without
92        affecting anything else. Note that the same mingw target plus all
93        the other distribution libraries and programs are now supported
94        when configuring with CMake (see 6 below) instead of with
95        Configure/Make.
97    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
98        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
99        exported in the Windows port". It has not yet been confirmed that the patch
100        solves the problem, but it does no harm.
102    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
103        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
104        with CMake, and also correct the comment about stack recursion.
106    7.  Remove the automatic building of pcredemo from the ./configure system and
107        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
108        of a program that users should build themselves after PCRE is installed, so
109        building it automatically is not really right. What is more, it gave
110        trouble in some build environments.
112    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
115    Version 7.5 10-Jan-08
116    ---------------------
118    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
119        values in parens when parsing an RE using the C++ wrapper."
121    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
122        Characters greater than 255 were excluded from the class instead of being
123        included.
125    3.  The same bug as (2) above applied to negated POSIX classes such as
126        [:^space:].
128    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
129        defined or documented. It seems to have been a typo for PCRE_STATIC, so
130        I have changed it.
132    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
133        first named subpattern) and a construct such as (?&a) would reference the
134        first named subpattern whose name started with "a" (in other words, the
135        length check was missing). Both these problems are fixed. "Subpattern name
136        expected" is now given for (?&) (a zero-length name), and this patch also
137        makes it give the same error for \k'' (previously it complained that that
138        was a reference to a non-existent subpattern).
140    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
141        this is right because (?- can be followed by option settings as well as by
142        digits. I have, however, made the messages clearer.
144    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
145        than the number used in the conditional) now cause a compile-time error.
146        This is actually not compatible with Perl, which accepts such patterns, but
147        treats the conditional as always being FALSE (as PCRE used to), but it
148        seems to me that giving a diagnostic is better.
150    8.  Change "alphameric" to the more common word "alphanumeric" in comments
151        and messages.
153    9.  Fix two occurrences of "backslash" in comments that should have been
154        "backspace".
156    10. Remove two redundant lines of code that can never be obeyed (their function
157        was moved elsewhere).
159    11. The program that makes PCRE's Unicode character property table had a bug
160        which caused it to generate incorrect table entries for sequences of
161        characters that have the same character type, but are in different scripts.
162        It amalgamated them into a single range, with the script of the first of
163        them. In other words, some characters were in the wrong script. There were
164        thirteen such cases, affecting characters in the following ranges:
166          U+002b0 - U+002c1
167          U+0060c - U+0060d
168          U+0061e - U+00612
169          U+0064b - U+0065e
170          U+0074d - U+0076d
171          U+01800 - U+01805
172          U+01d00 - U+01d77
173          U+01d9b - U+01dbf
174          U+0200b - U+0200f
175          U+030fc - U+030fe
176          U+03260 - U+0327f
177          U+0fb46 - U+0fbb1
178          U+10450 - U+1049d
180    12. The -o option (show only the matching part of a line) for pcregrep was not
181        compatible with GNU grep in that, if there was more than one match in a
182        line, it showed only the first of them. It now behaves in the same way as
183        GNU grep.
185    13. If the -o and -v options were combined for pcregrep, it printed a blank
186        line for every non-matching line. GNU grep prints nothing, and pcregrep now
187        does the same. The return code can be used to tell if there were any
188        non-matching lines.
190    14. Added --file-offsets and --line-offsets to pcregrep.
192    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
193        infinitely looping recursion. The bug was that positive lookaheads were not
194        being skipped when checking for a possible empty match (negative lookaheads
195        and both kinds of lookbehind were skipped).
197    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
198        inclusion of <windows.h> to before rather than after the definition of
199        INVALID_FILE_ATTRIBUTES (patch from David Byron).
201    17. Specifying a possessive quantifier with a specific limit for a Unicode
202        character property caused pcre_compile() to compile bad code, which led at
203        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
204        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
205        caused the error; without that there was no problem.
207    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
209    19. Added --enable-pcretest-libreadline.
211    20. In pcrecpp.cc, the variable 'count' was incremented twice in
212        RE::GlobalReplace(). As a result, the number of replacements returned was
213        double what it should be. I removed one of the increments, but Craig sent a
214        later patch that removed the other one (the right fix) and added unit tests
215        that check the return values (which was not done before).
217    21. Several CMake things:
219        (1) Arranged that, when cmake is used on Unix, the libraries end up with
220            the names libpcre and libpcreposix, not just pcre and pcreposix.
222        (2) The above change means that pcretest and pcregrep are now correctly
223            linked with the newly-built libraries, not previously installed ones.
227    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
228        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
229        UTF-8 newline character). The key issue is that the pattern starts .*;
230        this means that the match must be either at the beginning, or after a
231        newline. The bug was in the code for advancing after a failed match and
232        checking that the new position followed a newline. It was not taking
233        account of UTF-8 characters correctly.
235    23. PCRE was behaving differently from Perl in the way it recognized POSIX
236        character classes. PCRE was not treating the sequence [:...:] as a
237        character class unless the ... were all letters. Perl, however, seems to
238        allow any characters between [: and :], though of course it rejects as
239        unknown any "names" that contain non-letters, because all the known class
240        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
241        for example, whereas PCRE did not - it did not recognize a POSIX character
242        class. This seemed a bit dangerous, so the code has been changed to be
243        closer to Perl. The behaviour is not identical to Perl, because PCRE will
244        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
245        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
246        Perl does, and where it didn't before.
248    24. Rewrite so as to remove the single use of %n from pcregrep because in some
249        Windows environments %n is disabled by default.
252    Version 7.4 21-Sep-07
253    ---------------------
255    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
256        means that a class such as [\s] counted as "explicit reference to CR or
257        LF". That isn't really right - the whole point of the change was to try to
258        help when there was an actual mention of one of the two characters. So now
259        the change happens only if \r or \n (or a literal CR or LF) character is
260        encountered.
262    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
263        of both had grown to the point where there were only 3 bits left.
264        Fortunately, there was spare space in the data structure, and so I have
265        moved the internal flags into a new 16-bit field to free up more option
266        bits.
268    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
269        but did not set the internal JCHANGED flag - either of these is enough to
270        control the way the "get" function works - but the PCRE_INFO_JCHANGED
271        facility is supposed to tell if (?J) was ever used, so now (?J) at the
272        start sets both bits.
274    4.  Added options (at build time, compile time, exec time) to change \R from
275        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
277    5.  doc/pcresyntax.html was missing from the distribution.
279    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
280        compatibility, even though it is no longer used.
282    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
283        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
284        windows.h file is present (where different names are used). [This was
285        reversed later after testing - see 16 below.]
287    8.  Changed all #include <config.h> to #include "config.h". There were also
288        some further <pcre.h> cases that I changed to "pcre.h".
290    9.  When pcregrep was used with the --colour option, it missed the line ending
291        sequence off the lines that it output.
293    10. It was pointed out to me that arrays of string pointers cause lots of
294        relocations when a shared library is dynamically loaded. A technique of
295        using a single long string with a table of offsets can drastically reduce
296        these. I have refactored PCRE in four places to do this. The result is
297        dramatic:
299          Originally:                          290
300          After changing UCP table:            187
301          After changing error message table:   43
302          After changing table of "verbs"       36
303          After changing table of Posix names   22
305        Thanks to the folks working on Gregex for glib for this insight.
307    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
308        unicode-properties was also set.
310    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
312    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
313        checked only for CRLF.
315    14. Added casts to pcretest.c to avoid compiler warnings.
317    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
319    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
320        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
321        entirely. This removes changes made in 7 above.
323    17. The CMake files have been updated, and there is now more information about
324        building with CMake in the NON-UNIX-USE document.
327    Version 7.3 28-Aug-07
328    ---------------------
330     1. In the rejigging of the build system that eventually resulted in 7.1, the
331        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
332        brackets there is not right, since it causes compilers to look for an
333        installed pcre.h, not the version that is in the source that is being
334        compiled (which of course may be different). I have changed it back to:
336          #include "pcre.h"
338        I have a vague recollection that the change was concerned with compiling in
339        different directories, but in the new build system, that is taken care of
340        by the VPATH setting the Makefile.
342     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
343        when the subject happened to end in the byte 0x85 (e.g. if the last
344        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
345        characters but of course it shouldn't be taken as a newline when it is part
346        of another character. The bug was that, for an unlimited repeat of . in
347        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
348        characters when looking for a newline.
350     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
352     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
353        in debug output.
355     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
356        long printing in the pcrecpp unittest when running under MinGW.
358     6. ESC_K was left out of the EBCDIC table.
360     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
361        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
362        limit also applies to "virtual nesting" when a pattern is recursive, and in
363        this case 1000 isn't so big. I have been able to remove this limit at the
364        expense of backing off one optimization in certain circumstances. Normally,
365        when pcre_exec() would call its internal match() function recursively and
366        immediately return the result unconditionally, it uses a "tail recursion"
367        feature to save stack. However, when a subpattern that can match an empty
368        string has an unlimited repetition quantifier, it no longer makes this
369        optimization. That gives it a stack frame in which to save the data for
370        checking that an empty string has been matched. Previously this was taken
371        from the 1000-entry workspace that had been reserved. So now there is no
372        explicit limit, but more stack is used.
374     8. Applied Daniel's patches to solve problems with the import/export magic
375        syntax that is required for Windows, and which was going wrong for the
376        pcreposix and pcrecpp parts of the library. These were overlooked when this
377        problem was solved for the main library.
379     9. There were some crude static tests to avoid integer overflow when computing
380        the size of patterns that contain repeated groups with explicit upper
381        limits. As the maximum quantifier is 65535, the maximum group length was
382        set at 30,000 so that the product of these two numbers did not overflow a
383        32-bit integer. However, it turns out that people want to use groups that
384        are longer than 30,000 bytes (though not repeat them that many times).
385        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
386        made it possible to implement the integer overflow checks in a much more
387        dynamic way, which I have now done. The artificial limitation on group
388        length has been removed - we now have only the limit on the total length of
389        the compiled pattern, which depends on the LINK_SIZE setting.
391    10. Fixed a bug in the documentation for get/copy named substring when
392        duplicate names are permitted. If none of the named substrings are set, the
393        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
394        empty string.
396    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
397        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
398        because the ] is interpreted as the first data character and the
399        terminating ] is not found. PCRE has been made compatible with Perl in this
400        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
401        cause memory overwriting.
403    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
404        string has been matched (to stop an infinite loop). It was not recognizing
405        a conditional subpattern that could match an empty string if that
406        subpattern was within another subpattern. For example, it looped when
407        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
408        condition was not nested. This bug has been fixed.
410    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
411        past the start of the subject in the presence of bytes with the top bit
412        set, for example "\x8aBCD".
414    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
415        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
417    14. Optimized (?!) to (*FAIL).
419    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
420        This restricts code points to be within the range 0 to 0x10FFFF, excluding
421        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
422        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
423        does: it's just the validity check that is more restrictive.
425    16. Inserted checks for integer overflows during escape sequence (backslash)
426        processing, and also fixed erroneous offset values for syntax errors during
427        backslash processing.
429    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
430        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
432    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
433        caused an overrun.
435    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
436        something other than just ASCII characters) inside a group that had an
437        unlimited repeat caused a loop at compile time (while checking to see
438        whether the group could match an empty string).
440    20. Debugging a pattern containing \p or \P could cause a crash. For example,
441        [\P{Any}] did so. (Error in the code for printing property names.)
443    21. An orphan \E inside a character class could cause a crash.
445    22. A repeated capturing bracket such as (A)? could cause a wild memory
446        reference during compilation.
448    23. There are several functions in pcre_compile() that scan along a compiled
449        expression for various reasons (e.g. to see if it's fixed length for look
450        behind). There were bugs in these functions when a repeated \p or \P was
451        present in the pattern. These operators have additional parameters compared
452        with \d, etc, and these were not being taken into account when moving along
453        the compiled data. Specifically:
455        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
456            length.
458        (b) An item such as \pL+ within a repeated group could cause crashes or
459            loops.
461        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
462            "reference to non-existent subpattern" error.
464        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
466    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
467        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
469    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
471    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
472        character were causing crashes (broken optimization).
474    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
475        \p or \P) caused a compile-time loop.
477    28. More problems have arisen in unanchored patterns when CRLF is a valid line
478        break. For example, the unstudied pattern [\r\n]A does not match the string
479        "\r\nA" because change 7.0/46 below moves the current point on by two
480        characters after failing to match at the start. However, the pattern \nA
481        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
482        the same is true. There doesn't seem any very clean way out of this, but
483        what I have chosen to do makes the common cases work: PCRE now takes note
484        of whether there can be an explicit match for \r or \n anywhere in the
485        pattern, and if so, 7.0/46 no longer applies. As part of this change,
486        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
487        pattern has explicit CR or LF references.
489    29. Added (*CR) etc for changing newline setting at start of pattern.
492    Version 7.2 19-Jun-07
493    ---------------------
495     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
496        which is apparently normally available under Windows.
498     2. Re-jig the pcregrep tests with different newline settings in an attempt
499        to make them independent of the local environment's newline setting.
501     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
503     4. Some of the "internals" tests were previously cut out when the link size
504        was not 2, because the output contained actual offsets. The recent new
505        "Z" feature of pcretest means that these can be cut out, making the tests
506        usable with all link sizes.
508     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
509        stack recursion. This gives a massive performance boost under BSD, but just
510        a small improvement under Linux. However, it saves one field in the frame
511        in all cases.
513     6. Added more features from the forthcoming Perl 5.10:
515        (a) (?-n) (where n is a string of digits) is a relative subroutine or
516            recursion call. It refers to the nth most recently opened parentheses.
518        (b) (?+n) is also a relative subroutine call; it refers to the nth next
519            to be opened parentheses.
521        (c) Conditions that refer to capturing parentheses can be specified
522            relatively, for example, (?(-2)... or (?(+3)...
524        (d) \K resets the start of the current match so that everything before
525            is not part of it.
527        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
529        (f) \g{name} is another synonym - part of Perl 5.10's unification of
530            reference syntax.
532        (g) (?| introduces a group in which the numbering of parentheses in each
533            alternative starts with the same number.
535        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
537     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
540     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
541        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
542        for detecting groups that can match an empty string.
544     9. A pattern with a very large number of alternatives (more than several
545        hundred) was running out of internal workspace during the pre-compile
546        phase, where pcre_compile() figures out how much memory will be needed. A
547        bit of new cunning has reduced the workspace needed for groups with
548        alternatives. The 1000-alternative test pattern now uses 12 bytes of
549        workspace instead of running out of the 4096 that are available.
551    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
553    11. Applied patch from Google to remove an optimization that didn't quite work.
554        The report of the bug said:
556          pcrecpp::RE("a*").FullMatch("aaa") matches, while
557          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
558          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
560    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
561        it matched the wrong number of bytes.
564    Version 7.1 24-Apr-07
565    ---------------------
567     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
568        that is more "standard", making use of automake and other Autotools. There
569        is some re-arrangement of the files and adjustment of comments consequent
570        on this.
572     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
573        for recursive directory scanning broke on some systems because the files
574        are not scanned in any specific order and on different systems the order
575        was different. A call to "sort" has been inserted into RunGrepTest for the
576        approprate test as a short-term fix. In the longer term there may be an
577        alternative.
579     3. I had an email from Eric Raymond about problems translating some of PCRE's
580        man pages to HTML (despite the fact that I distribute HTML pages, some
581        people do their own conversions for various reasons). The problems
582        concerned the use of low-level troff macros .br and .in. I have therefore
583        removed all such uses from the man pages (some were redundant, some could
584        be replaced by .nf/.fi pairs). The 132html script that I use to generate
585        HTML has been updated to handle .nf/.fi and to complain if it encounters
586        .br or .in.
588     4. Updated comments in configure.ac that get placed in config.h.in and also
589        arranged for config.h to be included in the distribution, with the name
590        config.h.generic, for the benefit of those who have to compile without
591        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
593     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
594        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
595        makevp.bat for the current PCRE, using the additional files
596        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
598     6. A Windows user reported a minor discrepancy with test 2, which turned out
599        to be caused by a trailing space on an input line that had got lost in his
600        copy. The trailing space was an accident, so I've just removed it.
602     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
603        that is needed.
605     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
606        as "const" (a) because they are and (b) because it helps the PHP
607        maintainers who have recently made a script to detect big data structures
608        in the php code that should be moved to the .rodata section. I remembered
609        to update Builducptable as well, so it won't revert if ucptable.h is ever
610        re-created.
612     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
613        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
614        order to be able to cut out the UTF-8 tables in the latter when UTF-8
615        support is not required. This saves 1.5-2K of code, which is important in
616        some applications.
618        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
619        so as not to refer to the tables, even though these functions will never be
620        called when UTF-8 support is disabled. Otherwise there are problems with a
621        shared library.
623    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
625        (a) It was defining its arguments as char * instead of void *.
627        (b) It was assuming that all moves were upwards in memory; this was true
628            a long time ago when I wrote it, but is no longer the case.
630        The emulated memove() is provided for those environments that have neither
631        memmove() nor bcopy(). I didn't think anyone used it these days, but that
632        is clearly not the case, as these two bugs were recently reported.
634    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
635        and Detrail to create the HTML documentation, the .txt form of the man
636        pages, and it removes trailing spaces from listed files. It also creates
637        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
638        case, it wraps all the #defines with #ifndefs. This script should be run
639        before "make dist".
641    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
642        with Unicode property support.
644        (a) For a maximizing quantifier, if the two different cases of the
645            character were of different lengths in their UTF-8 codings (there are
646            some cases like this - I found 11), and the matching function had to
647            back up over a mixture of the two cases, it incorrectly assumed they
648            were both the same length.
650        (b) When PCRE was configured to use the heap rather than the stack for
651            recursion during matching, it was not correctly preserving the data for
652            the other case of a UTF-8 character when checking ahead for a match
653            while processing a minimizing repeat. If the check also involved
654            matching a wide character, but failed, corruption could cause an
655            erroneous result when trying to check for a repeat of the original
656            character.
658    13. Some tidying changes to the testing mechanism:
660        (a) The RunTest script now detects the internal link size and whether there
661            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
662            values substituted by "configure". (The RunGrepTest script already did
663            this for UTF-8.) The configure.ac script no longer substitutes the
664            relevant variables.
666        (b) The debugging options /B and /D in pcretest show the compiled bytecode
667            with length and offset values. This means that the output is different
668            for different internal link sizes. Test 2 is skipped for link sizes
669            other than 2 because of this, bypassing the problem. Unfortunately,
670            there was also a test in test 3 (the locale tests) that used /B and
671            failed for link sizes other than 2. Rather than cut the whole test out,
672            I have added a new /Z option to pcretest that replaces the length and
673            offset values with spaces. This is now used to make test 3 independent
674            of link size. (Test 2 will be tidied up later.)
676    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
677        segmentation fault instead of returning the appropriate error message.
679    15. In multiline mode when the newline sequence was set to "any", the pattern
680        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
681        This doesn't seem right; it now treats the CRLF combination as the line
682        ending, and so does not match in that case. It's only a pattern such as ^$
683        that would hit this one: something like ^ABC$ would have failed after \r
684        and then tried again after \r\n.
686    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
687        in an attempt to make files that differ only in their line terminators
688        compare equal. This works on Linux.
690    17. Under certain error circumstances pcregrep might try to free random memory
691        as it exited. This is now fixed, thanks to valgrind.
693    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
694        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
695        was because its rules for how to advance for /g after matching an empty
696        string at the end of a line did not allow for this case. They now check for
697        it specially.
699    20. pcretest is supposed to handle patterns and data of any length, by
700        extending its buffers when necessary. It was getting this wrong when the
701        buffer for a data line had to be extended.
703    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
704        CRLF as a newline sequence.
706    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
707        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
708        I have nevertheless tidied it up.
710    23. Added some casts to kill warnings from HP-UX ia64 compiler.
712    24. Added a man page for pcre-config.
715    Version 7.0 19-Dec-06
716    ---------------------
718     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
719        moving to gcc 4.1.1.
721     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
722        sys/time.h, which is documented as needed for this function. It doesn't
723        seem to matter on Linux, but it showed up on some releases of OS X.
725     3. It seems that there are systems where bytes whose values are greater than
726        127 match isprint() in the "C" locale. The "C" locale should be the
727        default when a C program starts up. In most systems, only ASCII printing
728        characters match isprint(). This difference caused the output from pcretest
729        to vary, making some of the tests fail. I have changed pcretest so that:
731        (a) When it is outputting text in the compiled version of a pattern, bytes
732            other than 32-126 are always shown as hex escapes.
734        (b) When it is outputting text that is a matched part of a subject string,
735            it does the same, unless a different locale has been set for the match
736            (using the /L modifier). In this case, it uses isprint() to decide.
738     4. Fixed a major bug that caused incorrect computation of the amount of memory
739        required for a compiled pattern when options that changed within the
740        pattern affected the logic of the preliminary scan that determines the
741        length. The relevant options are -x, and -i in UTF-8 mode. The result was
742        that the computed length was too small. The symptoms of this bug were
743        either the PCRE error "internal error: code overflow" from pcre_compile(),
744        or a glibc crash with a message such as "pcretest: free(): invalid next
745        size (fast)". Examples of patterns that provoked this bug (shown in
746        pcretest format) are:
748          /(?-x: )/x
749          /(?x)(?-x: \s*#\s*)/
750          /((?i)[\x{c0}])/8
751          /(?i:[\x{c0}])/8
753        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
754        is now done differently.
756     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
757        wrapper classes; (b) implement a new function in the C++ scanner that is
758        more efficient than the old way of doing things because it avoids levels of
759        recursion in the regex matching; (c) add a paragraph to the documentation
760        for the FullMatch() function.
762     6. The escape sequence \n was being treated as whatever was defined as
763        "newline". Not only was this contrary to the documentation, which states
764        that \n is character 10 (hex 0A), but it also went horribly wrong when
765        "newline" was defined as CRLF. This has been fixed.
767     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
768        was being set to -1 for the "end of line" case (supposedly a value that no
769        character can have). Though this value is never used (the check for end of
770        line is "zero bytes in current character"), it caused compiler complaints.
771        I've changed it to 0xffffffff.
773     8. In pcre_version.c, the version string was being built by a sequence of
774        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
775        string (as it is for production releases) called a macro with an empty
776        argument. The C standard says the result of this is undefined. The gcc
777        compiler treats it as an empty string (which was what was wanted) but it is
778        reported that Visual C gives an error. The source has been hacked around to
779        avoid this problem.
781     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
782        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
783        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
784        of them did).
786    10. Originally, pcretest opened its input and output without "b"; then I was
787        told that "b" was needed in some environments, so it was added for release
788        5.0 to both the input and output. (It makes no difference on Unix-like
789        systems.) Later I was told that it is wrong for the input on Windows. I've
790        now abstracted the modes into two macros, to make it easier to fiddle with
791        them, and removed "b" from the input mode under Windows.
793    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
795    12. Added -help and --help to pcretest as an official way of being reminded
796        of the options.
798    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
799        and pcrecpp.cc because they annoy compilers at high warning levels.
801    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
803    15. Fixed an occurrence of == in configure.ac that should have been = (shell
804        scripts are not C programs :-) and which was not noticed because it works
805        on Linux.
807    16. pcretest is supposed to handle any length of pattern and data line (as one
808        line or as a continued sequence of lines) by extending its input buffer if
809        necessary. This feature was broken for very long pattern lines, leading to
810        a string of junk being passed to pcre_compile() if the pattern was longer
811        than about 50K.
813    17. I have done a major re-factoring of the way pcre_compile() computes the
814        amount of memory needed for a compiled pattern. Previously, there was code
815        that made a preliminary scan of the pattern in order to do this. That was
816        OK when PCRE was new, but as the facilities have expanded, it has become
817        harder and harder to keep it in step with the real compile phase, and there
818        have been a number of bugs (see for example, 4 above). I have now found a
819        cunning way of running the real compile function in a "fake" mode that
820        enables it to compute how much memory it would need, while actually only
821        ever using a few hundred bytes of working memory and without too many
822        tests of the mode. This should make future maintenance and development
823        easier. A side effect of this work is that the limit of 200 on the nesting
824        depth of parentheses has been removed (though this was never a serious
825        limitation, I suspect). However, there is a downside: pcre_compile() now
826        runs more slowly than before (30% or more, depending on the pattern). I
827        hope this isn't a big issue. There is no effect on runtime performance.
829    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
830        newline (only possible for the last line of a file) and it was a
831        pattern that set a locale (followed by /Lsomething), pcretest crashed.
833    19. Added additional timing features to pcretest. (1) The -tm option now times
834        matching only, not compiling. (2) Both -t and -tm can be followed, as a
835        separate command line item, by a number that specifies the number of
836        repeats to use when timing. The default is 50000; this gives better
837        precision, but takes uncomfortably long for very large patterns.
839    20. Extended pcre_study() to be more clever in cases where a branch of a
840        subpattern has no definite first character. For example, (a*|b*)[cd] would
841        previously give no result from pcre_study(). Now it recognizes that the
842        first character must be a, b, c, or d.
844    21. There was an incorrect error "recursive call could loop indefinitely" if
845        a subpattern (or the entire pattern) that was being tested for matching an
846        empty string contained only one non-empty item after a nested subpattern.
847        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
848        incorrectly, because the \d was being skipped in the check.
850    22. The pcretest program now has a new pattern option /B and a command line
851        option -b, which is equivalent to adding /B to every pattern. This causes
852        it to show the compiled bytecode, without the additional information that
853        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
854        is the same as /B/I).
856    23. A new optimization is now able automatically to treat some sequences such
857        as a*b as a*+b. More specifically, if something simple (such as a character
858        or a simple class like \d) has an unlimited quantifier, and is followed by
859        something that cannot possibly match the quantified thing, the quantifier
860        is automatically "possessified".
862    24. A recursive reference to a subpattern whose number was greater than 39
863        went wrong under certain circumstances in UTF-8 mode. This bug could also
864        have affected the operation of pcre_study().
866    25. Realized that a little bit of performance could be had by replacing
867        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
869    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
871    27. Possessive quantifiers such as a++ were previously implemented by turning
872        them into atomic groups such as ($>a+). Now they have their own opcodes,
873        which improves performance. This includes the automatically created ones
874        from 23 above.
876    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
877        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
878        the first matched character to be a colon. This applied both to named and
879        numbered groups.
881    29. The ucpinternal.h header file was missing its idempotency #ifdef.
883    30. I was sent a "project" file called libpcre.a.dev which I understand makes
884        building PCRE on Windows easier, so I have included it in the distribution.
886    31. There is now a check in pcretest against a ridiculously large number being
887        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
888        loop, the loop is abandoned.
890    32. Forward references to subpatterns in conditions such as (?(2)...) where
891        subpattern 2 is defined later cause pcre_compile() to search forwards in
892        the pattern for the relevant set of parentheses. This search went wrong
893        when there were unescaped parentheses in a character class, parentheses
894        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
896    33. "Subroutine" calls and backreferences were previously restricted to
897        referencing subpatterns earlier in the regex. This restriction has now
898        been removed.
900    34. Added a number of extra features that are going to be in Perl 5.10. On the
901        whole, these are just syntactic alternatives for features that PCRE had
902        previously implemented using the Python syntax or my own invention. The
903        other formats are all retained for compatibility.
905        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
906            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
907            also .NET compatible.
909        (b) A recursion or subroutine call to a named group can now be defined as
910            (?&name) as well as (?P>name).
912        (c) A backreference to a named group can now be defined as \k<name> or
913            \k'name' as well as (?P=name). The new forms, as well as being in Perl
914            5.10, are also .NET compatible.
916        (d) A conditional reference to a named group can now use the syntax
917            (?(<name>) or (?('name') as well as (?(name).
919        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
920            groups (named and numbered) that are never evaluated inline, but can be
921            called as "subroutines" from elsewhere. In effect, the DEFINE condition
922            is always false. There may be only one alternative in such a group.
924        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
925            as the simple (?(R). The condition is true only if the most recent
926            recursion is that of the given number or name. It does not search out
927            through the entire recursion stack.
929        (g) The escape \gN or \g{N} has been added, where N is a positive or
930            negative number, specifying an absolute or relative reference.
932    35. Tidied to get rid of some further signed/unsigned compiler warnings and
933        some "unreachable code" warnings.
935    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
936        things, this adds five new scripts.
938    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
939        There were also incompatibilities regarding the handling of \Q..\E inside
940        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
941        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
943    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
944        matches an empty string, and forcibly breaks the loop. There were bugs in
945        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
946        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
947        separate and independent bugs (that affected different cases) have been
948        fixed.
950    39. Refactored the code to abolish the use of different opcodes for small
951        capturing bracket numbers. This is a tidy that I avoided doing when I
952        removed the limit on the number of capturing brackets for 3.5 back in 2001.
953        The new approach is not only tidier, it makes it possible to reduce the
954        memory needed to fix the previous bug (38).
956    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
957        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
958        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
959        mode.
961    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
962        report.
964    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
965        copy construction and assignment in the C++ wrapper.
967    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
968        couple of bugs that could have given wrong results in the "--newline=crlf"
969        case.
971    44. Added a number of casts and did some reorganization of signed/unsigned int
972        variables following suggestions from Dair Grant. Also renamed the variable
973        "this" as "item" because it is a C++ keyword.
975    45. Arranged for dftables to add
977          #include "pcre_internal.h"
979        to pcre_chartables.c because without it, gcc 4.x may remove the array
980        definition from the final binary if PCRE is built into a static library and
981        dead code stripping is activated.
983    46. For an unanchored pattern, if a match attempt fails at the start of a
984        newline sequence, and the newline setting is CRLF or ANY, and the next two
985        characters are CRLF, advance by two characters instead of one.
988    Version 6.7 04-Jul-06
989    ---------------------
991     1. In order to handle tests when input lines are enormously long, pcretest has
992        been re-factored so that it automatically extends its buffers when
993        necessary. The code is crude, but this _is_ just a test program. The
994        default size has been increased from 32K to 50K.
996     2. The code in pcre_study() was using the value of the re argument before
997        testing it for NULL. (Of course, in any sensible call of the function, it
998        won't be NULL.)
1000     3. The memmove() emulation function in pcre_internal.h, which is used on
1001        systems that lack both memmove() and bcopy() - that is, hardly ever -
1002        was missing a "static" storage class specifier.
1004     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1005        containing an extended class (one that cannot be represented by a bitmap
1006        because it contains high-valued characters or Unicode property items, e.g.
1007        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1008        pattern, but PCRE should not loop if you do not (it no longer does).
1009        [Detail: two cases were found: (a) a repeated subpattern containing an
1010        extended class; (b) a recursive reference to a subpattern that followed a
1011        previous extended class. It wasn't skipping over the extended class
1012        correctly when UTF-8 mode was not set.]
1014     5. A negated single-character class was not being recognized as fixed-length
1015        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1016        compile error "lookbehind assertion is not fixed length".
1018     6. The RunPerlTest auxiliary script was showing an unexpected difference
1019        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1020        write a Perl script that can interpret lines of an input file either as
1021        byte characters or as UTF-8, which is what "perltest" was being required to
1022        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1023        can't do is switch easily at run time between having the "use utf8;" pragma
1024        or not. In the end, I fudged it by using the RunPerlTest script to insert
1025        "use utf8;" explicitly for the UTF-8 tests.
1027     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1028        the end of the subject string, contrary to the documentation and to what
1029        Perl does. This was true of both matching functions. Now it matches only at
1030        the start of the subject and immediately after *internal* newlines.
1032     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1033        a pointer to an int instead of a pointer to an unsigned long int. This
1034        caused problems on 64-bit systems.
1036     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1037        instance of the 'standard' template library not being so standard".
1039    10. There was no check on the number of named subpatterns nor the maximum
1040        length of a subpattern name. The product of these values is used to compute
1041        the size of the memory block for a compiled pattern. By supplying a very
1042        long subpattern name and a large number of named subpatterns, the size
1043        computation could be caused to overflow. This is now prevented by limiting
1044        the length of names to 32 characters, and the number of named subpatterns
1045        to 10,000.
1047    11. Subpatterns that are repeated with specific counts have to be replicated in
1048        the compiled pattern. The size of memory for this was computed from the
1049        length of the subpattern and the repeat count. The latter is limited to
1050        65535, but there was no limit on the former, meaning that integer overflow
1051        could in principle occur. The compiled length of a repeated subpattern is
1052        now limited to 30,000 bytes in order to prevent this.
1054    12. Added the optional facility to have named substrings with the same name.
1056    13. Added the ability to use a named substring as a condition, using the
1057        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1058        are numbers (not recommended). Forward references are permitted.
1060    14. Added forward references in named backreferences (if you see what I mean).
1062    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1063        pattern could run off the end of the subject. For example, the pattern
1064        "(?s)(.{1,5})"8 did this with the subject "ab".
1066    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1067        PCRE_CASELESS was set when matching characters that were quantified with ?
1068        or *.
1070    17. A character class other than a single negated character that had a minimum
1071        but no maximum quantifier - for example [ab]{6,} - was not handled
1072        correctly by pce_dfa_exec(). It would match only one character.
1074    18. A valid (though odd) pattern that looked like a POSIX character
1075        class but used an invalid character after [ (for example [[,abc,]]) caused
1076        pcre_compile() to give the error "Failed: internal error: code overflow" or
1077        in some cases to crash with a glibc free() error. This could even happen if
1078        the pattern terminated after [[ but there just happened to be a sequence of
1079        letters, a binary zero, and a closing ] in the memory that followed.
1081    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1082        over the years. Originally (before any Unicode support), just the bottom 8
1083        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1084        output from "man perlunicode" includes this:
1086          The regular expression compiler produces polymorphic opcodes.  That
1087          is, the pattern adapts to the data and automatically switches to
1088          the Unicode character scheme when presented with Unicode data--or
1089          instead uses a traditional byte scheme when presented with byte
1090          data.
1092        Sadly, a wide octal escape does not cause a switch, and in a string with
1093        no other multibyte characters, these octal escapes are treated as before.
1094        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1095        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1096        Unicode string.
1098        I have not perpetrated such confusion in PCRE. Up till now, it took just
1099        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1100        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1101        translate to the appropriate multibyte character.
1103    29. Applied some refactoring to reduce the number of warnings from Microsoft
1104        and Borland compilers. This has included removing the fudge introduced
1105        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1106        a warning about an unused variable.
1108    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1109        characters since release 4.0, because Perl (from release 5.004) does not.
1110        [Or at least, is documented not to: some releases seem to be in conflict
1111        with the documentation.] However, when a pattern was studied with
1112        pcre_study() and all its branches started with \s, PCRE still included VT
1113        as a possible starting character. Of course, this did no harm; it just
1114        caused an unnecessary match attempt.
1116    22. Removed a now-redundant internal flag bit that recorded the fact that case
1117        dependency changed within the pattern. This was once needed for "required
1118        byte" processing, but is no longer used. This recovers a now-scarce options
1119        bit. Also moved the least significant internal flag bit to the most-
1120        significant bit of the word, which was not previously used (hangover from
1121        the days when it was an int rather than a uint) to free up another bit for
1122        the future.
1124    23. Added support for CRLF line endings as well as CR and LF. As well as the
1125        default being selectable at build time, it can now be changed at runtime
1126        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1127        specify that it is scanning data with non-default line endings.
1129    24. Changed the definition of CXXLINK to make it agree with the definition of
1130        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1132    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1133        recursions. This makes a big different to stack usage for some patterns.
1135    26. If a subpattern containing a named recursion or subroutine reference such
1136        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1137        the space required for the compiled pattern went wrong and gave too small a
1138        value. Depending on the environment, this could lead to "Failed: internal
1139        error: code overflow at offset 49" or "glibc detected double free or
1140        corruption" errors.
1142    27. Applied patches from Google (a) to support the new newline modes and (b) to
1143        advance over multibyte UTF-8 characters in GlobalReplace.
1145    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1146        difference for some implementation of PCRE in some Windows version.
1148    29. Added some extra testing facilities to pcretest:
1150        \q<number>   in a data line sets the "match limit" value
1151        \Q<number>   in a data line sets the "match recursion limt" value
1152        -S <number>  sets the stack size, where <number> is in megabytes
1154        The -S option isn't available for Windows.
1157    Version 6.6 06-Feb-06
1158    ---------------------
1160     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1161        in pcreposix.h. I have copied the definition from pcre.h.
1163     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1164        because pcre.h is no longer a built file.
1166     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1167        not normally included in the compiled code.
1170    Version 6.5 01-Feb-06
1171    ---------------------
1173     1. When using the partial match feature with pcre_dfa_exec(), it was not
1174        anchoring the second and subsequent partial matches at the new starting
1175        point. This could lead to incorrect results. For example, with the pattern
1176        /1234/, partially matching against "123" and then "a4" gave a match.
1178     2. Changes to pcregrep:
1180        (a) All non-match returns from pcre_exec() were being treated as failures
1181            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1182            error message is output. Some extra information is given for the
1183            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1184            probably the only errors that are likely to be caused by users (by
1185            specifying a regex that has nested indefinite repeats, for instance).
1186            If there are more than 20 of these errors, pcregrep is abandoned.
1188        (b) A binary zero was treated as data while matching, but terminated the
1189            output line if it was written out. This has been fixed: binary zeroes
1190            are now no different to any other data bytes.
1192        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1193            used to set a locale for matching. The --locale=xxxx long option has
1194            been added (no short equivalent) to specify a locale explicitly on the
1195            pcregrep command, overriding the environment variables.
1197        (d) When -B was used with -n, some line numbers in the output were one less
1198            than they should have been.
1200        (e) Added the -o (--only-matching) option.
1202        (f) If -A or -C was used with -c (count only), some lines of context were
1203            accidentally printed for the final match.
1205        (g) Added the -H (--with-filename) option.
1207        (h) The combination of options -rh failed to suppress file names for files
1208            that were found from directory arguments.
1210        (i) Added the -D (--devices) and -d (--directories) options.
1212        (j) Added the -F (--fixed-strings) option.
1214        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1216        (l) Added the --colo(u)r option.
1218        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1219            is not present by default.
1221     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1222        items such as (?R) or (?1), when the recursion could match a number of
1223        alternatives. If it matched one of the alternatives, but subsequently,
1224        outside the recursion, there was a failure, the code tried to back up into
1225        the recursion. However, because of the way PCRE is implemented, this is not
1226        possible, and the result was an incorrect result from the match.
1228        In order to prevent this happening, the specification of recursion has
1229        been changed so that all such subpatterns are automatically treated as
1230        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1232     4. I had overlooked the fact that, in some locales, there are characters for
1233        which isalpha() is true but neither isupper() nor islower() are true. In
1234        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1235        and ordfeminine) are like this. This affected the treatment of \w and \W
1236        when they appeared in character classes, but not when they appeared outside
1237        a character class. The bit map for "word" characters is now created
1238        separately from the results of isalnum() instead of just taking it from the
1239        upper, lower, and digit maps. (Plus the underscore character, of course.)
1241     5. The above bug also affected the handling of POSIX character classes such as
1242        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1243        permanent tables. Instead, the bit maps for such a class were previously
1244        created as the appropriate unions of the upper, lower, and digit bitmaps.
1245        Now they are created by subtraction from the [[:word:]] class, which has
1246        its own bitmap.
1248     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1249        It is created by subtracting the vertical space characters (\x09, \x0a,
1250        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1251        subtraction was done in the overall bitmap for a character class, meaning
1252        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1253        be recognized. This bug has been fixed.
1255     7. Patches from the folks at Google:
1257          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1258          real life, but is still worth protecting against".
1260          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1261          regular expressions".
1263          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1264          have it.
1266          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1267          "configure" and the latter not, in order to fix a problem somebody had
1268          with compiling the Arg class on HP-UX.
1270          (e) Improve the error-handling of the C++ wrapper a little bit.
1272          (f) New tests for checking recursion limiting.
1274     8. The pcre_memmove() function, which is used only if the environment does not
1275        have a standard memmove() function (and is therefore rarely compiled),
1276        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1277        returning a result (though PCRE never actually uses the result).
1279     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1280        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1281        returned instead of calling malloc() with an overflowing number that would
1282        most likely cause subsequent chaos.
1284    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1286    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1287        with this option is matched, the nmatch and pmatch options of regexec() are
1288        ignored.
1290    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1291        provided in case anyone wants to the the POSIX interface with UTF-8
1292        strings.
1294    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1295        C++ linking (needed for some HP-UX environments).
1297    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1298        (unused parameter) and in the pcre_printint() function (omitted "default"
1299        switch label when the default is to do nothing).
1301    15. Added some code to make it possible, when PCRE is compiled as a C++
1302        library, to replace subject pointers for pcre_exec() with a smart pointer
1303        class, thus making it possible to process discontinuous strings.
1305    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1306        much the same function. They were added by different people who were trying
1307        to make PCRE easy to compile on non-Unix systems. It has been suggested
1308        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1309        for compiling on Windows systems. I have therefore replaced it with
1310        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1311        defaults to "extern" for C or "extern C" for C++, which works fine on
1312        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1313        SCOPE with something explicit in config.h. In addition:
1315        (a) pcreposix.h still had just "extern" instead of either of these macros;
1316            I have replaced it with PCRE_DATA_SCOPE.
1318        (b) Functions such as _pcre_xclass(), which are internal to the library,
1319            but external in the C sense, all had PCRE_EXPORT in their definitions.
1320            This is apparently wrong for the Windows case, so I have removed it.
1321            (It makes no difference on Unix-like systems.)
1323    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1324        of recursive calls to match(). This is different to MATCH_LIMIT because
1325        that limits the total number of calls to match(), not all of which increase
1326        the depth of recursion. Limiting the recursion depth limits the amount of
1327        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1328        when PCRE is compiled, and changed at run time. A patch from Google adds
1329        this functionality to the C++ interface.
1331    18. Changes to the handling of Unicode character properties:
1333        (a) Updated the table to Unicode 4.1.0.
1335        (b) Recognize characters that are not in the table as "Cn" (undefined).
1337        (c) I revised the way the table is implemented to a much improved format
1338            which includes recognition of ranges. It now supports the ranges that
1339            are defined in UnicodeData.txt, and it also amalgamates other
1340            characters into ranges. This has reduced the number of entries in the
1341            table from around 16,000 to around 3,000, thus reducing its size
1342            considerably. I realized I did not need to use a tree structure after
1343            all - a binary chop search is just as efficient. Having reduced the
1344            number of entries, I extended their size from 6 bytes to 8 bytes to
1345            allow for more data.
1347        (d) Added support for Unicode script names via properties such as \p{Han}.
1349    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1350        matching that character.
1352    20. When matching a repeated Unicode property with a minimum greater than zero,
1353        (for example \pL{2,}), PCRE could look past the end of the subject if it
1354        reached it while seeking the minimum number of characters. This could
1355        happen only if some of the characters were more than one byte long, because
1356        there is a check for at least the minimum number of bytes.
1358    21. Refactored the implementation of \p and \P so as to be more general, to
1359        allow for more different types of property in future. This has changed the
1360        compiled form incompatibly. Anybody with saved compiled patterns that use
1361        \p or \P will have to recompile them.
1363    22. Added "Any" and "L&" to the supported property types.
1365    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1366        but give a compile time error if the value is greater than 0xff.
1368    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1369        accidentally not being installed or uninstalled.
1371    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1372        made were to insert the current release number. This seemed silly, because
1373        it made things harder for people building PCRE on systems that don't run
1374        "configure". I have turned pcre.h into a distributed file, no longer built
1375        by "configure", with the version identification directly included. There is
1376        no longer a pcre.h.in file.
1378        However, this change necessitated a change to the pcre-config script as
1379        well. It is built from pcre-config.in, and one of the substitutions was the
1380        release number. I have updated configure.ac so that ./configure now finds
1381        the release number by grepping pcre.h.
1383    26. Added the ability to run the tests under valgrind.
1386    Version 6.4 05-Sep-05
1387    ---------------------
1389     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1390        "--" to be printed when multiple files were scanned, even when none of the
1391        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1392        consider it to be a bug, and have restored the previous behaviour.
1394     2. A couple of code tidies to get rid of compiler warnings.
1396     3. The pcretest program used to cheat by referring to symbols in the library
1397        whose names begin with _pcre_. These are internal symbols that are not
1398        really supposed to be visible externally, and in some environments it is
1399        possible to suppress them. The cheating is now confined to including
1400        certain files from the library's source, which is a bit cleaner.
1402     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1403        file's purpose clearer.
1405     5. Reorganized pcre_ucp_findchar().
1408    Version 6.3 15-Aug-05
1409    ---------------------
1411     1. The file libpcre.pc.in did not have general read permission in the tarball.
1413     2. There were some problems when building without C++ support:
1415        (a) If C++ support was not built, "make install" and "make test" still
1416            tried to test it.
1418        (b) There were problems when the value of CXX was explicitly set. Some
1419            changes have been made to try to fix these, and ...
1421        (c) --disable-cpp can now be used to explicitly disable C++ support.
1423        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1424            backslash in a target when C++ was disabled. This confuses some
1425            versions of "make", apparently. Using an intermediate variable solves
1426            this. (Same for CPP_LOBJ.)
1428     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1429        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1430        necessary on certain architectures.
1432     4. Added a setting of -export-symbols-regex to the link command to remove
1433        those symbols that are exported in the C sense, but actually are local
1434        within the library, and not documented. Their names all begin with
1435        "_pcre_". This is not a perfect job, because (a) we have to except some
1436        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1437        available (and never for static libraries). I have made a note to try to
1438        find a way round (a) in the future.
1441    Version 6.2 01-Aug-05
1442    ---------------------
1444     1. There was no test for integer overflow of quantifier values. A construction
1445        such as {1111111111111111} would give undefined results. What is worse, if
1446        a minimum quantifier for a parenthesized subpattern overflowed and became
1447        negative, the calculation of the memory size went wrong. This could have
1448        led to memory overwriting.
1450     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1452     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1453        operating environments where this matters.
1455     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1456        PCRE options from within the C++ wrapper.
1458     5. Named capturing subpatterns were not being correctly counted when a pattern
1459        was compiled. This caused two problems: (a) If there were more than 100
1460        such subpatterns, the calculation of the memory needed for the whole
1461        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1462        back references of the form \12, where the number was greater than 9, were
1463        not recognized as back references, even though there were sufficient
1464        previous subpatterns.
1466     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1467        versions of gcc, e.g. 2.95.4.
1470    Version 6.1 21-Jun-05
1471    ---------------------
1473     1. There was one reference to the variable "posix" in pcretest.c that was not
1474        surrounded by "#if !defined NOPOSIX".
1476     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1477        the cross-check on the old pcre_info() function, for the benefit of the
1478        cut-down version of PCRE that is currently imported into Exim.
1480     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1481        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1482        patterns that start (?i) but I don't think that matters. The use of (?i) is
1483        just an example; this all applies to the other options as well.
1485     4. Since libtool seems to echo the compile commands it is issuing, the output
1486        from "make" can be reduced a bit by putting "@" in front of each libtool
1487        compile command.
1489     5. Patch from the folks at Google for configure.in to be a bit more thorough
1490        in checking for a suitable C++ installation before trying to compile the
1491        C++ stuff. This should fix a reported problem when a compiler was present,
1492        but no suitable headers.
1494     6. The man pages all had just "PCRE" as their title. I have changed them to
1495        be the relevant file name. I have also arranged that these names are
1496        retained in the file doc/pcre.txt, which is a concatenation in text format
1497        of all the man pages except the little individual ones for each function.
1499     7. The NON-UNIX-USE file had not been updated for the different set of source
1500        files that come with release 6. I also added a few comments about the C++
1501        wrapper.
1504    Version 6.0 07-Jun-05
1505    ---------------------
1507     1. Some minor internal re-organization to help with my DFA experiments.
1509     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1510        didn't matter for the library itself when fully configured, but did matter
1511        when compiling without UCP support, or within Exim, where the ucp files are
1512        not imported.
1514     3. Refactoring of the library code to split up the various functions into
1515        different source modules. The addition of the new DFA matching code (see
1516        below) to a single monolithic source would have made it really too
1517        unwieldy, quite apart from causing all the code to be include in a
1518        statically linked application, when only some functions are used. This is
1519        relevant even without the DFA addition now that patterns can be compiled in
1520        one application and matched in another.
1522        The downside of splitting up is that there have to be some external
1523        functions and data tables that are used internally in different modules of
1524        the library but which are not part of the API. These have all had their
1525        names changed to start with "_pcre_" so that they are unlikely to clash
1526        with other external names.
1528     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1529        a different (DFA) algorithm. Although it is slower than the original
1530        function, it does have some advantages for certain types of matching
1531        problem.
1533     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1534        including restarting after a partial match.
1536     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1537        defined when compiling for Windows was sent to me. I have put it into the
1538        code, though I have no means of testing or verifying it.
1540     7. Added the pcre_refcount() auxiliary function.
1542     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1543        match before or at the first newline in the subject string. In pcretest,
1544        the /f option on a pattern can be used to set this.
1546     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1547        would behave wrongly. This has been present in PCRE since release 4.0.
1549    10. A number of changes to the pcregrep command:
1551        (a) Refactored how -x works; insert ^(...)$ instead of setting
1552            PCRE_ANCHORED and checking the length, in preparation for adding
1553            something similar for -w.
1555        (b) Added the -w (match as a word) option.
1557        (c) Refactored the way lines are read and buffered so as to have more
1558            than one at a time available.
1560        (d) Implemented a pcregrep test script.
1562        (e) Added the -M (multiline match) option. This allows patterns to match
1563            over several lines of the subject. The buffering ensures that at least
1564            8K, or the rest of the document (whichever is the shorter) is available
1565            for matching (and similarly the previous 8K for lookbehind assertions).
1567        (f) Changed the --help output so that it now says
1569              -w, --word-regex(p)
1571            instead of two lines, one with "regex" and the other with "regexp"
1572            because that confused at least one person since the short forms are the
1573            same. (This required a bit of code, as the output is generated
1574            automatically from a table. It wasn't just a text change.)
1576        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1577            option but starts with a hyphen. Could be a pattern or a path name
1578            starting with a hyphen, for instance.
1580        (h) "-" can be given as a file name to represent stdin.
1582        (i) When file names are being printed, "(standard input)" is used for
1583            the standard input, for compatibility with GNU grep. Previously
1584            "<stdin>" was used.
1586        (j) The option --label=xxx can be used to supply a name to be used for
1587            stdin when file names are being printed. There is no short form.
1589        (k) Re-factored the options decoding logic because we are going to add
1590            two more options that take data. Such options can now be given in four
1591            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1593        (l) Added the -A, -B, and -C options for requesting that lines of context
1594            around matches be printed.
1596        (m) Added the -L option to print the names of files that do not contain
1597            any matching lines, that is, the complement of -l.
1599        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1600            continue to scan other files.
1602        (o) The -s option was incorrectly implemented. For compatibility with other
1603            greps, it now suppresses the error message for a non-existent or non-
1604            accessible file (but not the return code). There is a new option called
1605            -q that suppresses the output of matching lines, which was what -s was
1606            previously doing.
1608        (p) Added --include and --exclude options to specify files for inclusion
1609            and exclusion when recursing.
1611    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1612        Hopefully, it now does.
1614    12. Missing cast in pcre_study().
1616    13. Added an "uninstall" target to the makefile.
1618    14. Replaced "extern" in the function prototypes in Makefile.in with
1619        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1620        world, but is set differently for Windows.
1622    15. Added a second compiling function called pcre_compile2(). The only
1623        difference is that it has an extra argument, which is a pointer to an
1624        integer error code. When there is a compile-time failure, this is set
1625        non-zero, in addition to the error test pointer being set to point to an
1626        error message. The new argument may be NULL if no error number is required
1627        (but then you may as well call pcre_compile(), which is now just a
1628        wrapper). This facility is provided because some applications need a
1629        numeric error indication, but it has also enabled me to tidy up the way
1630        compile-time errors are handled in the POSIX wrapper.
1632    16. Added VPATH=.libs to the makefile; this should help when building with one
1633        prefix path and installing with another. (Or so I'm told by someone who
1634        knows more about this stuff than I do.)
1636    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1637        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1638        match everything, including newlines. This is not POSIX-compatible, but
1639        somebody wanted the feature. From pcretest it can be activated by using
1640        both the P and the s flags.
1642    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1644    19. libpcre.pc was being incorrectly installed as executable.
1646    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1647        it now also looks for '\r' so that it will work unmodified on Windows.
1649    21. Added Google's contributed C++ wrapper to the distribution.
1651    22. Added some untidy missing memory free() calls in pcretest, to keep
1652        Electric Fence happy when testing.
1656    Version 5.0 13-Sep-04
1657    ---------------------
1659     1. Internal change: literal characters are no longer packed up into items
1660        containing multiple characters in a single byte-string. Each character
1661        is now matched using a separate opcode. However, there may be more than one
1662        byte in the character in UTF-8 mode.
1664     2. The pcre_callout_block structure has two new fields: pattern_position and
1665        next_item_length. These contain the offset in the pattern to the next match
1666        item, and its length, respectively.
1668     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1669        insertion of callouts before each pattern item. Added the /C option to
1670        pcretest to make use of this.
1672     4. On the advice of a Windows user, the lines
1674          #if defined(_WIN32) || defined(WIN32)
1675          _setmode( _fileno( stdout ), 0x8000 );
1676          #endif  /* defined(_WIN32) || defined(WIN32) */
1678        have been added to the source of pcretest. This apparently does useful
1679        magic in relation to line terminators.
1681     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1682        for the benefit of those environments where the "b" makes a difference.
1684     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1685        to know about it. I have put a hack into configure.in that adds in code
1686        to set GCC=yes if CC=icc. This seems to end up at a point in the
1687        generated configure script that is early enough to affect the setting of
1688        compiler options, which is what is needed, but I have no means of testing
1689        whether it really works. (The user who reported this had patched the
1690        generated configure script, which of course I cannot do.)
1692        LATER: After change 22 below (new libtool files), the configure script
1693        seems to know about icc (and also ecc). Therefore, I have commented out
1694        this hack in configure.in.
1696     7. Added support for pkg-config (2 patches were sent in).
1698     8. Negated POSIX character classes that used a combination of internal tables
1699        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1700        [[:^ascii]]. Typically, they would match almost any characters. The other
1701        POSIX classes were not broken in this way.
1703     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1704        to find the match, as PCRE was deluded into thinking that the match had to
1705        start at the start point or following a newline. The same bug applied to
1706        patterns with negative forward assertions or any backward assertions
1707        preceding ".*" at the start, unless the pattern required a fixed first
1708        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1710    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1711        starting at the last subject character, bytes beyond the end of the subject
1712        string were read.
1714    11. Renamed the variable "class" as "classbits" to make life easier for C++
1715        users. (Previously there was a macro definition, but it apparently wasn't
1716        enough.)
1718    12. Added the new field "tables" to the extra data so that tables can be passed
1719        in at exec time, or the internal tables can be re-selected. This allows
1720        a compiled regex to be saved and re-used at a later time by a different
1721        program that might have everything at different addresses.
1723    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1724        -R library as well as a -L library.
1726    14. The debugging options of pcretest (-d on the command line or D on a
1727        pattern) showed incorrect output for anything following an extended class
1728        that contained multibyte characters and which was followed by a quantifier.
1730    15. Added optional support for general category Unicode character properties
1731        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1732        support. It adds about 90K to the size of the library. The meanings of the
1733        inbuilt class escapes such as \d and \s have NOT been changed.
1735    16. Updated pcredemo.c to include calls to free() to release the memory for the
1736        compiled pattern.
1738    17. The generated file chartables.c was being created in the source directory
1739        instead of in the building directory. This caused the build to fail if the
1740        source directory was different from the building directory, and was
1741        read-only.
1743    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1744        file. No doubt somebody will tell me if they don't make sense... Also added
1745        Dan Mooney's comments about building on OpenVMS.
1747    19. Added support for partial matching via the PCRE_PARTIAL option for
1748        pcre_exec() and the \P data escape in pcretest.
1750    20. Extended pcretest with 3 new pattern features:
1752        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1753              write the compiled pattern to the file whose name is "rest-of-line".
1754              This is a straight binary dump of the data, with the saved pointer to
1755              the character tables forced to be NULL. The study data, if any, is
1756              written too. After writing, pcretest reads a new pattern.
1758        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1759              compiled pattern from the given file. There must not be any
1760              occurrences of "<" in the file name (pretty unlikely); if there are,
1761              pcretest will instead treat the initial "<" as a pattern delimiter.
1762              After reading in the pattern, pcretest goes on to read data lines as
1763              usual.
1765        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1766              and 16-bit fields in a compiled pattern, to simulate a pattern that
1767              was compiled on a host of opposite endianness.
1769    21. The pcre-exec() function can now cope with patterns that were compiled on
1770        hosts of opposite endianness, with this restriction:
1772          As for any compiled expression that is saved and used later, the tables
1773          pointer field cannot be preserved; the extra_data field in the arguments
1774          to pcre_exec() should be used to pass in a tables address if a value
1775          other than the default internal tables were used at compile time.
1777    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1778        now diagnosed as an error. Previously, most of the time, a negative number
1779        would have been treated as zero, but if in addition "ovector" was passed as
1780        NULL, a crash could occur.
1782    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1783        new versions from the libtool 1.5 distribution (the last one is a copy of
1784        a file called libtool.m4). This seems to have fixed the need to patch
1785        "configure" to support Darwin 1.3 (which I used to do). However, I still
1786        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1787        workstation).
1789    24. Changed the PCRE licence to be the more standard "BSD" licence.
1792    Version 4.5 01-Dec-03
1793    ---------------------
1795     1. There has been some re-arrangement of the code for the match() function so
1796        that it can be compiled in a version that does not call itself recursively.
1797        Instead, it keeps those local variables that need separate instances for
1798        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1799        needs to "recurse". Keeping track of where control must go is done by means
1800        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1801        hide most of the details from the main code, and operates only if
1802        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1803        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1804        operating.
1806        To make it easier for callers to provide specially tailored get/free
1807        functions for this usage, two new functions, pcre_stack_malloc, and
1808        pcre_stack_free, are used. They are always called in strict stacking order,
1809        and the size of block requested is always the same.
1811        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1812        PCRE has been compiled to use the stack or the heap for recursion. The
1813        -C option of pcretest uses this to show which version is compiled.
1815        A new data escape \S, is added to pcretest; it causes the amounts of store
1816        obtained and freed by both kinds of malloc/free at match time to be added
1817        to the output.
1819     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1820        what's available on my current Linux desktop machine.
1822     3. When matching a UTF-8 string, the test for a valid string at the start has
1823        been extended. If start_offset is not zero, PCRE now checks that it points
1824        to a byte that is the start of a UTF-8 character. If not, it returns
1825        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1826        this is necessary because there may be backward assertions in the pattern.
1827        When matching the same subject several times, it may save resources to use
1828        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1830     4. The code for checking the validity of UTF-8 strings has been tightened so
1831        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1832        containing "overlong sequences".
1834     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1835        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1836        should have been "&", but it just so happened that all the cases this let
1837        through by mistake were picked up later in the function.
1839     6. I had used a variable called "isblank" - this is a C99 function, causing
1840        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1842     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1843        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1844        so the version is shown; (c) stop "make test" echoing "./RunTest".
1846     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1848     9. The prototype for memmove() for systems that don't have it was using
1849        size_t, but the inclusion of the header that defines size_t was later. I've
1850        moved the #includes for the C headers earlier to avoid this.
1852    10. Added some adjustments to the code to make it easier to compiler on certain
1853        special systems:
1855          (a) Some "const" qualifiers were missing.
1856          (b) Added the macro EXPORT before all exported functions; by default this
1857              is defined to be empty.
1858          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1859              that it reads its output file name as an argument instead of writing
1860              to the standard output and assuming this can be redirected.
1862    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1863        class containing characters with values greater than 255, PCRE compilation
1864        went into a loop.
1866    12. A recursive reference to a subpattern that was within another subpattern
1867        that had a minimum quantifier of zero caused PCRE to crash. For example,
1868        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1869        recursion. If the recursively-called subpattern itself had a zero repeat,
1870        that was OK.
1872    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1873        buffer into which it was copied (for escape processing) was still set at
1874        1024, so long lines caused crashes.
1876    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1877        "internal error: code overflow...". This applied to any character class
1878        that was followed by a possessive quantifier.
1880    15. Modified the Makefile to add libpcre.la as a prerequisite for
1881        libpcreposix.la because I was told this is needed for a parallel build to
1882        work.
1884    16. If a pattern that contained .* following optional items at the start was
1885        studied, the wrong optimizing data was generated, leading to matching
1886        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1887        matching string must start with a or b or c. The correct conclusion for
1888        this pattern is that a match can start with any character.
1891    Version 4.4 13-Aug-03
1892    ---------------------
1894     1. In UTF-8 mode, a character class containing characters with values between
1895        127 and 255 was not handled correctly if the compiled pattern was studied.
1896        In fixing this, I have also improved the studying algorithm for such
1897        classes (slightly).
1899     2. Three internal functions had redundant arguments passed to them. Removal
1900        might give a very teeny performance improvement.
1902     3. Documentation bug: the value of the capture_top field in a callout is *one
1903        more than* the number of the hightest numbered captured substring.
1905     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1906        in incorrectly linking with a previously installed version. They now link
1907        explicitly with libpcre.la.
1909     5. configure.in no longer needs to recognize Cygwin specially.
1911     6. A problem in pcre.in for Windows platforms is fixed.
1913     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1914        pcretest, it used to include the size of the study block as part of its
1915        output. Unfortunately, the structure contains a field that has a different
1916        size on different hardware architectures. This meant that the tests that
1917        showed this size failed. As the block is currently always of a fixed size,
1918        this information isn't actually particularly useful in pcretest output, so
1919        I have just removed it.
1921     8. Three pre-processor statements accidentally did not start in column 1.
1922        Sadly, there are *still* compilers around that complain, even though
1923        standard C has not required this for well over a decade. Sigh.
1925     9. In pcretest, the code for checking callouts passed small integers in the
1926        callout_data field, which is a void * field. However, some picky compilers
1927        complained about the casts involved for this on 64-bit systems. Now
1928        pcretest passes the address of the small integer instead, which should get
1929        rid of the warnings.
1931    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1932        both compile and run time, and gives an error if an invalid UTF-8 sequence
1933        is found. There is a option for disabling this check in cases where the
1934        string is known to be correct and/or the maximum performance is wanted.
1936    11. In response to a bug report, I changed one line in Makefile.in from
1938            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1939        to
1940            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1942        to look similar to other lines, but I have no way of telling whether this
1943        is the right thing to do, as I do not use Windows. No doubt I'll get told
1944        if it's wrong...
1947    Version 4.3 21-May-03
1948    ---------------------
1950    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1951       Makefile.
1953    2. Some refactoring to improve the quality of the code:
1955       (i)   The utf8_table... variables are now declared "const".
1957       (ii)  The code for \cx, which used the "case flipping" table to upper case
1958             lower case letters, now just substracts 32. This is ASCII-specific,
1959             but the whole concept of \cx is ASCII-specific, so it seems
1960             reasonable.
1962       (iii) PCRE was using its character types table to recognize decimal and
1963             hexadecimal digits in the pattern. This is silly, because it handles
1964             only 0-9, a-f, and A-F, but the character types table is locale-
1965             specific, which means strange things might happen. A private
1966             table is now used for this - though it costs 256 bytes, a table is
1967             much faster than multiple explicit tests. Of course, the standard
1968             character types table is still used for matching digits in subject
1969             strings against \d.
1971       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1972             ending in _t are). So I've renamed it as ESC_tee.
1974    3. The first argument for regexec() in the POSIX wrapper should have been
1975       defined as "const".
1977    4. Changed pcretest to use malloc() for its buffers so that they can be
1978       Electric Fenced for debugging.
1980    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1981       to read one or more bytes before the start of the subject string. Often this
1982       had no effect on PCRE's behaviour, but in some circumstances it could
1983       provoke a segmentation fault.
1985    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1986       to try to read one or more bytes before the start of the subject string.
1988    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1989       UTF-8 support could misbehave in various ways if the subject string
1990       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1991       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1992       back over UTF-8 characters.)
1995    Version 4.2 14-Apr-03
1996    ---------------------
1998    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
2000    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
2001         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
2002         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
2003         [WIN_PREFIX]: new variable, "cyg" for Cygwin
2004         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
2005           and BUILD_EXEEXT
2006         Note: automatic setting of the BUILD variables is not yet working
2007         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
2008           compile-time but not at link-time
2009         [LINK]: use for linking executables only
2010         make different versions for Windows and non-Windows
2011         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
2012           libraries
2013         [LINK_FOR_BUILD]: new variable
2014         [OBJEXT]: use throughout
2015         [EXEEXT]: use throughout
2016         <winshared>: new target
2017         <wininstall>: new target
2018         <dftables.o>: use native compiler
2019         <dftables>: use native linker
2020         <install>: handle Windows platform correctly
2021         <clean>: ditto
2022         <check>: ditto
2023         copy DLL to top builddir before testing
2025       As part of these changes, -no-undefined was removed again. This was reported
2026       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
2027       in any case.
2029    3. Some tidies to get rid of compiler warnings:
2031       . In the match_data structure, match_limit was an unsigned long int, whereas
2032         match_call_count was an int. I've made them both unsigned long ints.
2034       . In pcretest the fact that a const uschar * doesn't automatically cast to
2035         a void * provoked a warning.
2037       . Turning on some more compiler warnings threw up some "shadow" variables
2038         and a few more missing casts.
2040    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
2041       option, a class that contained a single character with a value between 128
2042       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
2044    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
2045       option, a class that contained several characters, but with at least one
2046       whose value was between 128 and 255 caused PCRE to crash.
2049    Version 4.1 12-Mar-03
2050    ---------------------
2052    1. Compiling with gcc -pedantic found a couple of places where casts were
2053    needed, and a string in dftables.c that was longer than standard compilers are
2054    required to support.
2056    2. Compiling with Sun's compiler found a few more places where the code could
2057    be tidied up in order to avoid warnings.
2059    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
2060    first of these names is deprecated in the latest Autoconf in favour of the name
2061    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
2062    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
2063    analogy I have changed it to CFLAGS_FOR_BUILD.
2065    4. Added -no-undefined to the linking command in the Makefile, because this is
2066    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2067    linking step for the pcreposix library.
2069    5. PCRE was failing to diagnose the case of two named groups with the same
2070    name.
2072    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2073    literal character that is needed in the subject for a match, and scans along to
2074    ensure that it is present before embarking on the full matching process. This
2075    saves time in cases of nested unlimited repeats that are never going to match.
2076    Problem: the scan can take a lot of time if the subject is very long (e.g.
2077    megabytes), thus penalizing straightforward matches. It is now done only if the
2078    amount of subject to be scanned is less than 1000 bytes.
2080    7. A lesser problem with the same optimization is that it was recording the
2081    first character of an anchored pattern as "needed", thus provoking a search
2082    right along the subject, even when the first match of the pattern was going to
2083    fail. The "needed" character is now not set for anchored patterns, unless it
2084    follows something in the pattern that is of non-fixed length. Thus, it still
2085    fulfils its original purpose of finding quick non-matches in cases of nested
2086    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2089    Version 4.0 17-Feb-03
2090    ---------------------
2092    1. If a comment in an extended regex that started immediately after a meta-item
2093    extended to the end of string, PCRE compiled incorrect data. This could lead to
2094    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2096    2. Moved to autoconf 2.53 and libtool 1.4.2.
2098    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2099    the special perltest8 script is no longer needed - all the tests can be run
2100    from a single perltest script.
2102    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2103    by \s. It has now been removed in PCRE. This means it isn't recognized as
2104    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2105    class [:space:] *does* include VT, thereby creating a mess.
2107    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2108    space and tab.
2110    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2111    its new features into the main test script, reducing the number of scripts.
2113    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2114    were backward compatible, and made the (?i) apply to the whole pattern, as if
2115    /i were given. Now it behaves more logically, and applies the option setting
2116    only to what follows. PCRE has been changed to follow suit. However, if it
2117    finds options settings right at the start of the pattern, it extracts them into
2118    the global options, as before. Thus, they show up in the info data.
2120    8. Added support for the \Q...\E escape sequence. Characters in between are
2121    treated as literals. This is slightly different from Perl in that $ and @ are
2122    also handled as literals inside the quotes. In Perl, they will cause variable
2123    interpolation. Note the following examples:
2125        Pattern            PCRE matches      Perl matches
2127        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2128        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2129        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2131    For compatibility with Perl, \Q...\E sequences are recognized inside character
2132    classes as well as outside them.
2134    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2135    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2136    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2137    signed/unsigned warnings.
2139    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2140    option for pcretest, so I've replaced it by a simple function that does just
2141    that job.
2143    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2144    "pcregrep -".
2146    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2147    Java package. This provides some syntactic sugar for simple cases of what my
2148    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2149    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2150    item, you can use this simplified notation. Note that only makes sense with
2151    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2152    greediness, whatever the setting of the PCRE_UNGREEDY option.
2154    13. A change of greediness default within a pattern was not taking effect at
2155    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2156    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2157    was abstracted outside.
2159    14. PCRE now supports the \G assertion. It is true when the current matching
2160    position is at the start point of the match. This differs from \A when the
2161    starting offset is non-zero. Used with the /g option of pcretest (or similar
2162    code), it works in the same way as it does for Perl's /g option. If all
2163    alternatives of a regex begin with \G, the expression is anchored to the start
2164    match position, and the "anchored" flag is set in the compiled expression.
2166    15. Some bugs concerning the handling of certain option changes within patterns
2167    have been fixed. These applied to options other than (?ims). For example,
2168    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2169    been the other way round. Some of this was related to change 7 above.
2171    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2172    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2173    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2174    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2176    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2177    mode. Unlike ".", it always matches newline, whatever the setting of
2178    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2179    assertions. Perl allows it, but it doesn't (in general) work because it can't
2180    calculate the length of the lookbehind. At least, that's the case for Perl
2181    5.8.0 - I've been told they are going to document that it doesn't work in
2182    future.
2184    18. Added an error diagnosis for escapes that PCRE does not support: these are
2185    \L, \l, \N, \P, \p, \U, \u, and \X.
2187    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2188    reading past the end of the pattern in cases such as /[abcd/.
2190    20. PCRE was getting more memory than necessary for patterns with classes that
2191    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2193    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2194    compiling PCRE for use with Virtual Pascal.
2196    22. Small fix to the Makefile to make it work properly if the build is done
2197    outside the source tree.
2199    23. Added a new extension: a condition to go with recursion. If a conditional
2200    subpattern starts with (?(R) the "true" branch is used if recursion has
2201    happened, whereas the "false" branch is used only at the top level.
2203    24. When there was a very long string of literal characters (over 255 bytes
2204    without UTF support, over 250 bytes with UTF support), the computation of how
2205    much memory was required could be incorrect, leading to segfaults or other
2206    strange effects.
2208    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2209    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2210    there was a subsequent back reference to those brackets. This meant that, for
2211    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2212    possible to check for precisely this case. All we can do is abandon the
2213    optimization if .* occurs inside capturing brackets when there are any back
2214    references whatsoever. (See below for a better fix that came later.)
2216    26. The handling of the optimization for finding the first character of a
2217    non-anchored pattern, and for finding a character that is required later in the
2218    match were failing in some cases. This didn't break the matching; it just
2219    failed to optimize when it could. The way this is done has been re-implemented.
2221    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2223    28. Added a new feature that provides some of the functionality that Perl
2224    provides with (?{...}). The facility is termed a "callout". The way it is done
2225    in PCRE is for the caller to provide an optional function, by setting
2226    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2227    global variable. By default it is unset, which disables all calling out. To get
2228    the function called, the regex must include (?C) at appropriate points. This
2229    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2230    This provides a means of identifying different callout points. When PCRE
2231    reaches such a point in the regex, if pcre_callout has been set, the external
2232    function is called. It is provided with data in a structure called
2233    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2234    matching continues; if it returns a non-zero value, the match at the current
2235    point fails. However, backtracking will occur if possible. [This was changed
2236    later and other features added - see item 49 below.]
2238    29. pcretest is upgraded to test the callout functionality. It provides a
2239    callout function that displays information. By default, it shows the start of
2240    the match and the current position in the text. There are some new data escapes
2241    to vary what happens:
2243        \C+         in addition, show current contents of captured substrings
2244        \C-         do not supply a callout function
2245        \C!n        return 1 when callout number n is reached
2246        \C!n!m      return 1 when callout number n is reached for the mth time
2248    30. If pcregrep was called with the -l option and just a single file name, it
2249    output "<stdin>" if a match was found, instead of the file name.
2251    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2252    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2253    pcre_exec(). This saves a malloc/free per call. The default value of
2254    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2255    when configuring.
2257    32. The default maximum size of a compiled pattern is 64K. There have been a
2258    few cases of people hitting this limit. The code now uses macros to handle the
2259    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2260    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2261    configuring. Tests 2 and 5 work only with 2-byte links because they output
2262    debugging information about compiled patterns.
2264    33. Internal code re-arrangements:
2266    (a) Moved the debugging function for printing out a compiled regex into
2267        its own source file (printint.c) and used #include to pull it into
2268        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2269        separate copies.
2271    (b) Defined the list of op-code names for debugging as a macro in
2272        internal.h so that it is next to the definition of the opcodes.
2274    (c) Defined a table of op-code lengths for simpler skipping along compiled
2275        code. This is again a macro in internal.h so that it is next to the
2276        definition of the opcodes.
2278    34. Added support for recursive calls to individual subpatterns, along the
2279    lines of Robin Houston's patch (but implemented somewhat differently).
2281    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2282    allow it to read and process whole directories in Win32. This code was
2283    contributed by Lionel Fourquaux; it has not been tested by me.
2285    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2286    used to name a group. Names consist of alphanumerics and underscores, and must
2287    be unique. Back references use the syntax (?P=name) and recursive calls use
2288    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2289    numbers. The function pcre_fullinfo() can be used after compilation to extract
2290    a name/number map. There are three relevant calls:
2292      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2293      PCRE_INFO_NAMECOUNT            yields the number of entries
2294      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2296    The map is a vector of fixed-size entries. The size of each entry depends on
2297    the length of the longest name used. The first two bytes of each entry are the
2298    group number, most significant byte first. There follows the corresponding
2299    name, zero terminated. The names are in alphabetical order.
2301    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2302    case instead of 255. Making it the same both with and without UTF-8 support
2303    means that the same test output works with both.
2305    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2306    calling malloc() with a zero argument.
2308    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2309    optimization. I've improved things by keeping a bitmap of backreferences with
2310    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2311    fact referenced, the optimization can be applied. It is unlikely that a
2312    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2313    the match to follow \n) will appear inside brackets with a number greater than
2314    31, but if it does, any back reference > 31 suppresses the optimization.
2316    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2317    of disabling numbered capturing parentheses. Any opening parenthesis that is
2318    not followed by ? behaves as if it were followed by ?: but named parentheses
2319    can still be used for capturing (and they will acquire numbers in the usual
2320    way).
2322    41. Redesigned the return codes from the match() function into yes/no/error so
2323    that errors can be passed back from deep inside the nested calls. A malloc
2324    failure while inside a recursive subpattern call now causes the
2325    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2327    42. It is now possible to set a limit on the number of times the match()
2328    function is called in a call to pcre_exec(). This facility makes it possible to
2329    limit the amount of recursion and backtracking, though not in a directly
2330    obvious way, because the match() function is used in a number of different
2331    circumstances. The count starts from zero for each position in the subject
2332    string (for non-anchored patterns). The default limit is, for compatibility, a
2333    large number, namely 10 000 000. You can change this in two ways:
2335    (a) When configuring PCRE before making, you can use --with-match-limit=n
2336        to set a default value for the compiled library.
2338    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2339        a different value is set. See 45 below.
2341    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2343    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2344    of things that can be changed at compile time. The first argument specifies
2345    what is wanted and the second points to where the information is to be placed.
2346    The current list of available information is:
2348      PCRE_CONFIG_UTF8
2350    The output is an integer that is set to one if UTF-8 support is available;
2351    otherwise it is set to zero.
2355    The output is an integer that it set to the value of the code that is used for
2356    newline. It is either LF (10) or CR (13).
2360    The output is an integer that contains the number of bytes used for internal
2361    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2365    The output is an integer that contains the threshold above which the POSIX
2366    interface uses malloc() for output vectors. See item 31 above.
2370    The output is an unsigned integer that contains the default limit of the number
2371    of match() calls in a pcre_exec() execution. See 42 above.
2373    44. pcretest has been upgraded by the addition of the -C option. This causes it
2374    to extract all the available output from the new pcre_config() function, and to
2375    output it. The program then exits immediately.
2377    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2378    order to support additional features. One way would have been to define
2379    pcre_exec2() (for example) with extra arguments, but this would not have been
2380    extensible, and would also have required all calls to the original function to
2381    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2382    is used for passing in "extra" data from pcre_study().
2384    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2385    contains the following fields:
2387      flags         a bitmap indicating which of the following fields are set
2388      study_data    opaque data from pcre_study()
2389      match_limit   a way of specifying a limit on match() calls for a specific
2390                      call to pcre_exec()
2391      callout_data  data for callouts (see 49 below)
2393    The flag bits are also defined in pcre.h, and are
2399    The pcre_study() function now returns one of these new pcre_extra blocks, with
2400    the actual study data pointed to by the study_data field, and the
2401    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2402    before. That is, this change is entirely upwards-compatible and requires no
2403    change to existing code.
2405    If you want to pass in additional data to pcre_exec(), you can either place it
2406    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2407    block.
2409    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2410    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2411    times with different match limits, until it finds the minimum value needed for
2412    pcre_exec() to complete. The value is then output. This can be instructive; for
2413    most simple matches the number is quite small, but for pathological cases it
2414    gets very large very quickly.
2416    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2417    returns the size of the data block pointed to by the study_data field in a
2418    pcre_extra block, that is, the value that was passed as the argument to
2419    pcre_malloc() when PCRE was getting memory in which to place the information
2420    created by pcre_study(). The fourth argument should point to a size_t variable.
2421    pcretest has been extended so that this information is shown after a successful
2422    pcre_study() call when information about the compiled regex is being displayed.
2424    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2425    because what follows is always an absolute path. (Later: it turns out that this
2426    is more than cosmetic for MinGW, because it doesn't like empty path
2427    components.)
2429    49. Some changes have been made to the callout feature (see 28 above):
2431    (i)  A callout function now has three choices for what it returns:
2433           0  =>  success, carry on matching
2434         > 0  =>  failure at this point, but backtrack if possible
2435         < 0  =>  serious error, return this value from pcre_exec()
2437         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2438         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2439         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2440         use by callout functions. It will never be used by PCRE itself.
2442    (ii) The pcre_extra structure (see 45 above) has a void * field called
2443         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2444         pcre_callout_block structure has a field of the same name. The contents of
2445         the field passed in the pcre_extra structure are passed to the callout
2446         function in the corresponding field in the callout block. This makes it
2447         easier to use the same callout-containing regex from multiple threads. For
2448         testing, the pcretest program has a new data escape
2450           \C*n        pass the number n (may be negative) as callout_data
2452         If the callout function in pcretest receives a non-zero value as
2453         callout_data, it returns that value.
2455    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2456    there were some redundant $(CFLAGS) in commands that are now specified as
2457    $(LINK), which already includes $(CFLAGS).
2459    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2460    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2461    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2462    one-byte characters throughout. Note that case-insensitive matching applies
2463    only to characters whose values are less than 256. PCRE doesn't support the
2464    notion of cases for higher-valued characters.
2466    (i)   A character class whose characters are all within 0-255 is handled as
2467          a bit map, and the map is inverted for negative classes. Previously, a
2468          character > 255 always failed to match such a class; however it should
2469          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2471    (ii)  A negated character class with a single character < 255 is coded as
2472          "not this character" (OP_NOT). This wasn't working properly when the test
2473          character was multibyte, either singly or repeated.
2475    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2476          mode, for example: \x{100}{2,3}.
2478    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2479          singly or repeated) now correctly test multibyte characters. However,
2480          PCRE doesn't recognize any characters with values greater than 255 as
2481          digits, spaces, or word characters. Such characters always match \D, \S,
2482          and \W, and never match \d, \s, or \w.
2484    (v)   Classes may now contain characters and character ranges with values
2485          greater than 255. For example: [ab\x{100}-\x{400}].
2487    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2488          PCRE in UTF-8 mode.
2490    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2491    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2492    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2493    value.)
2495    53. The single man page has become too large. I have therefore split it up into
2496    a number of separate man pages. These also give rise to individual HTML pages;
2497    these are now put in a separate directory, and there is an index.html page that
2498    lists them all. Some hyperlinking between the pages has been installed.
2500    54. Added convenience functions for handling named capturing parentheses.
2502    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2503    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2504    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2505    are faulted.
2507    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2508    calling configure. These values are used when compiling the dftables.c program
2509    which is run to generate the source of the default character tables. They
2510    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2511    you will need to set these values.
2513    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2516    Version 3.9 02-Jan-02
2517  ---------------------  ---------------------
2519  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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