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revision 51 by nigel, Sat Feb 24 21:39:37 2007 UTC revision 349 by ph10, Wed Jul 2 18:42:11 2008 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 8.0 02 Jul-08
5    ---------------------
7    1.  Replaced UCP searching code with optimized version as implemented for Ad
8        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
9        stage table and inline lookup instead of a function, giving speed ups of 2
10        to 5 times on some simple patterns that I tested. Permission was given to
11        distribute the MultiStage2.py script that generates the tables (it's not in
12        the tarball, but is in the Subversion repository).
15    Version 7.7 07-May-08
16    ---------------------
18    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
19        a string to a long long, pretend we don't even have a long long." This is
20        done by checking for the strtoq, strtoll, and _strtoi64 functions.
22    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
23        pre-7.6 versions, which defined a global no_arg variable instead of putting
24        it in the RE class. (See also #8 below.)
26    3.  Remove a line of dead code, identified by coverity and reported by Nuno
27        Lopes.
29    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
31        (1) The include/exclude patterns were being applied to the whole pathnames
32            of files, instead of just to the final components.
34        (2) If there was more than one level of directory, the subdirectories were
35            skipped unless they satisfied the include/exclude conditions. This is
36            inconsistent with GNU grep (and could even be seen as contrary to the
37            pcregrep specification - which I improved to make it absolutely clear).
38            The action now is always to scan all levels of directory, and just
39            apply the include/exclude patterns to regular files.
41    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
42        --exclude_dir in the tests to avoid scanning .svn directories.
44    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
45        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
46        doesn't support NULs in patterns.
48    7.  Added some missing "const"s to declarations of static tables in
49        pcre_compile.c and pcre_dfa_exec.c.
51    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
52        caused by fix #2  above. (Subsequently also a second patch to fix the
53        first patch. And a third patch - this was a messy problem.)
55    9.  Applied Craig's patch to remove the use of push_back().
57    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
58        matching function regexec().
60    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
61        which, however, unlike Perl's \g{...}, are subroutine calls, not back
62        references. PCRE supports relative numbers with this syntax (I don't think
63        Oniguruma does).
65    12. Previously, a group with a zero repeat such as (...){0} was completely
66        omitted from the compiled regex. However, this means that if the group
67        was called as a subroutine from elsewhere in the pattern, things went wrong
68        (an internal error was given). Such groups are now left in the compiled
69        pattern, with a new opcode that causes them to be skipped at execution
70        time.
72    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
73        to the way PCRE behaves:
75        (a) A lone ] character is dis-allowed (Perl treats it as data).
77        (b) A back reference to an unmatched subpattern matches an empty string
78            (Perl fails the current match path).
80        (c) A data ] in a character class must be notated as \] because if the
81            first data character in a class is ], it defines an empty class. (In
82            Perl it is not possible to have an empty class.) The empty class []
83            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
84            The negative empty class [^] matches any one character, independently
85            of the DOTALL setting.
87    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
88        non-existent subpattern following a character class starting with ']' and
89        containing () gave an internal compiling error instead of "reference to
90        non-existent subpattern". Fortunately, when the pattern did exist, the
91        compiled code was correct. (When scanning forwards to check for the
92        existencd of the subpattern, it was treating the data ']' as terminating
93        the class, so got the count wrong. When actually compiling, the reference
94        was subsequently set up correctly.)
96    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
97        it was being rejected as not supported by pcre_dfa_exec(), even though
98        other assertions are supported. I have made pcre_dfa_exec() support
99        (*FAIL).
101    16. The implementation of 13c above involved the invention of a new opcode,
102        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
103        cannot be changed at match time, I realized I could make a small
104        improvement to matching performance by compiling OP_ALLANY instead of
105        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
106        on the OP_ANY path.
108    17. Compiling pcretest on Windows with readline support failed without the
109        following two fixes: (1) Make the unistd.h include conditional on
110        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
112    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
113        ncurses library to be included for pcretest when ReadLine support is
114        requested, but also to allow for it to be overridden. This patch came from
115        Daniel Bergström.
117    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
118        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
119        any errors with the current Unicode tables. Thanks to Peter Kankowski for
120        spotting this.
123    Version 7.6 28-Jan-08
124    ---------------------
126    1.  A character class containing a very large number of characters with
127        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
128        overflow.
130    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
131        HAVE_LONG_LONG is not defined.
133    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
134        bring them up to date and include new features. This patch includes:
136        - Fixed PH's badly added libz and libbz2 support.
137        - Fixed a problem with static linking.
138        - Added pcredemo. [But later removed - see 7 below.]
139        - Fixed dftables problem and added an option.
140        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
141            HAVE_LONG_LONG.
142        - Added readline support for pcretest.
143        - Added an listing of the option settings after cmake has run.
145    4.  A user submitted a patch to Makefile that makes it easy to create
146        "pcre.dll" under mingw when using Configure/Make. I added stuff to
147        Makefile.am that cause it to include this special target, without
148        affecting anything else. Note that the same mingw target plus all
149        the other distribution libraries and programs are now supported
150        when configuring with CMake (see 6 below) instead of with
151        Configure/Make.
153    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
154        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
155        exported in the Windows port". It has not yet been confirmed that the patch
156        solves the problem, but it does no harm.
158    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
159        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
160        with CMake, and also correct the comment about stack recursion.
162    7.  Remove the automatic building of pcredemo from the ./configure system and
163        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
164        of a program that users should build themselves after PCRE is installed, so
165        building it automatically is not really right. What is more, it gave
166        trouble in some build environments.
168    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
171    Version 7.5 10-Jan-08
172    ---------------------
174    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
175        values in parens when parsing an RE using the C++ wrapper."
177    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
178        Characters greater than 255 were excluded from the class instead of being
179        included.
181    3.  The same bug as (2) above applied to negated POSIX classes such as
182        [:^space:].
184    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
185        defined or documented. It seems to have been a typo for PCRE_STATIC, so
186        I have changed it.
188    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
189        first named subpattern) and a construct such as (?&a) would reference the
190        first named subpattern whose name started with "a" (in other words, the
191        length check was missing). Both these problems are fixed. "Subpattern name
192        expected" is now given for (?&) (a zero-length name), and this patch also
193        makes it give the same error for \k'' (previously it complained that that
194        was a reference to a non-existent subpattern).
196    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
197        this is right because (?- can be followed by option settings as well as by
198        digits. I have, however, made the messages clearer.
200    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
201        than the number used in the conditional) now cause a compile-time error.
202        This is actually not compatible with Perl, which accepts such patterns, but
203        treats the conditional as always being FALSE (as PCRE used to), but it
204        seems to me that giving a diagnostic is better.
206    8.  Change "alphameric" to the more common word "alphanumeric" in comments
207        and messages.
209    9.  Fix two occurrences of "backslash" in comments that should have been
210        "backspace".
212    10. Remove two redundant lines of code that can never be obeyed (their function
213        was moved elsewhere).
215    11. The program that makes PCRE's Unicode character property table had a bug
216        which caused it to generate incorrect table entries for sequences of
217        characters that have the same character type, but are in different scripts.
218        It amalgamated them into a single range, with the script of the first of
219        them. In other words, some characters were in the wrong script. There were
220        thirteen such cases, affecting characters in the following ranges:
222          U+002b0 - U+002c1
223          U+0060c - U+0060d
224          U+0061e - U+00612
225          U+0064b - U+0065e
226          U+0074d - U+0076d
227          U+01800 - U+01805
228          U+01d00 - U+01d77
229          U+01d9b - U+01dbf
230          U+0200b - U+0200f
231          U+030fc - U+030fe
232          U+03260 - U+0327f
233          U+0fb46 - U+0fbb1
234          U+10450 - U+1049d
236    12. The -o option (show only the matching part of a line) for pcregrep was not
237        compatible with GNU grep in that, if there was more than one match in a
238        line, it showed only the first of them. It now behaves in the same way as
239        GNU grep.
241    13. If the -o and -v options were combined for pcregrep, it printed a blank
242        line for every non-matching line. GNU grep prints nothing, and pcregrep now
243        does the same. The return code can be used to tell if there were any
244        non-matching lines.
246    14. Added --file-offsets and --line-offsets to pcregrep.
248    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
249        infinitely looping recursion. The bug was that positive lookaheads were not
250        being skipped when checking for a possible empty match (negative lookaheads
251        and both kinds of lookbehind were skipped).
253    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
254        inclusion of <windows.h> to before rather than after the definition of
255        INVALID_FILE_ATTRIBUTES (patch from David Byron).
257    17. Specifying a possessive quantifier with a specific limit for a Unicode
258        character property caused pcre_compile() to compile bad code, which led at
259        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
260        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
261        caused the error; without that there was no problem.
263    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
265    19. Added --enable-pcretest-libreadline.
267    20. In pcrecpp.cc, the variable 'count' was incremented twice in
268        RE::GlobalReplace(). As a result, the number of replacements returned was
269        double what it should be. I removed one of the increments, but Craig sent a
270        later patch that removed the other one (the right fix) and added unit tests
271        that check the return values (which was not done before).
273    21. Several CMake things:
275        (1) Arranged that, when cmake is used on Unix, the libraries end up with
276            the names libpcre and libpcreposix, not just pcre and pcreposix.
278        (2) The above change means that pcretest and pcregrep are now correctly
279            linked with the newly-built libraries, not previously installed ones.
283    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
284        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
285        UTF-8 newline character). The key issue is that the pattern starts .*;
286        this means that the match must be either at the beginning, or after a
287        newline. The bug was in the code for advancing after a failed match and
288        checking that the new position followed a newline. It was not taking
289        account of UTF-8 characters correctly.
291    23. PCRE was behaving differently from Perl in the way it recognized POSIX
292        character classes. PCRE was not treating the sequence [:...:] as a
293        character class unless the ... were all letters. Perl, however, seems to
294        allow any characters between [: and :], though of course it rejects as
295        unknown any "names" that contain non-letters, because all the known class
296        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
297        for example, whereas PCRE did not - it did not recognize a POSIX character
298        class. This seemed a bit dangerous, so the code has been changed to be
299        closer to Perl. The behaviour is not identical to Perl, because PCRE will
300        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
301        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
302        Perl does, and where it didn't before.
304    24. Rewrite so as to remove the single use of %n from pcregrep because in some
305        Windows environments %n is disabled by default.
308    Version 7.4 21-Sep-07
309    ---------------------
311    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
312        means that a class such as [\s] counted as "explicit reference to CR or
313        LF". That isn't really right - the whole point of the change was to try to
314        help when there was an actual mention of one of the two characters. So now
315        the change happens only if \r or \n (or a literal CR or LF) character is
316        encountered.
318    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
319        of both had grown to the point where there were only 3 bits left.
320        Fortunately, there was spare space in the data structure, and so I have
321        moved the internal flags into a new 16-bit field to free up more option
322        bits.
324    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
325        but did not set the internal JCHANGED flag - either of these is enough to
326        control the way the "get" function works - but the PCRE_INFO_JCHANGED
327        facility is supposed to tell if (?J) was ever used, so now (?J) at the
328        start sets both bits.
330    4.  Added options (at build time, compile time, exec time) to change \R from
331        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
333    5.  doc/pcresyntax.html was missing from the distribution.
335    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
336        compatibility, even though it is no longer used.
338    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
339        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
340        windows.h file is present (where different names are used). [This was
341        reversed later after testing - see 16 below.]
343    8.  Changed all #include <config.h> to #include "config.h". There were also
344        some further <pcre.h> cases that I changed to "pcre.h".
346    9.  When pcregrep was used with the --colour option, it missed the line ending
347        sequence off the lines that it output.
349    10. It was pointed out to me that arrays of string pointers cause lots of
350        relocations when a shared library is dynamically loaded. A technique of
351        using a single long string with a table of offsets can drastically reduce
352        these. I have refactored PCRE in four places to do this. The result is
353        dramatic:
355          Originally:                          290
356          After changing UCP table:            187
357          After changing error message table:   43
358          After changing table of "verbs"       36
359          After changing table of Posix names   22
361        Thanks to the folks working on Gregex for glib for this insight.
363    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
364        unicode-properties was also set.
366    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
368    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
369        checked only for CRLF.
371    14. Added casts to pcretest.c to avoid compiler warnings.
373    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
375    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
376        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
377        entirely. This removes changes made in 7 above.
379    17. The CMake files have been updated, and there is now more information about
380        building with CMake in the NON-UNIX-USE document.
383    Version 7.3 28-Aug-07
384    ---------------------
386     1. In the rejigging of the build system that eventually resulted in 7.1, the
387        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
388        brackets there is not right, since it causes compilers to look for an
389        installed pcre.h, not the version that is in the source that is being
390        compiled (which of course may be different). I have changed it back to:
392          #include "pcre.h"
394        I have a vague recollection that the change was concerned with compiling in
395        different directories, but in the new build system, that is taken care of
396        by the VPATH setting the Makefile.
398     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
399        when the subject happened to end in the byte 0x85 (e.g. if the last
400        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
401        characters but of course it shouldn't be taken as a newline when it is part
402        of another character. The bug was that, for an unlimited repeat of . in
403        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
404        characters when looking for a newline.
406     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
408     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
409        in debug output.
411     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
412        long printing in the pcrecpp unittest when running under MinGW.
414     6. ESC_K was left out of the EBCDIC table.
416     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
417        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
418        limit also applies to "virtual nesting" when a pattern is recursive, and in
419        this case 1000 isn't so big. I have been able to remove this limit at the
420        expense of backing off one optimization in certain circumstances. Normally,
421        when pcre_exec() would call its internal match() function recursively and
422        immediately return the result unconditionally, it uses a "tail recursion"
423        feature to save stack. However, when a subpattern that can match an empty
424        string has an unlimited repetition quantifier, it no longer makes this
425        optimization. That gives it a stack frame in which to save the data for
426        checking that an empty string has been matched. Previously this was taken
427        from the 1000-entry workspace that had been reserved. So now there is no
428        explicit limit, but more stack is used.
430     8. Applied Daniel's patches to solve problems with the import/export magic
431        syntax that is required for Windows, and which was going wrong for the
432        pcreposix and pcrecpp parts of the library. These were overlooked when this
433        problem was solved for the main library.
435     9. There were some crude static tests to avoid integer overflow when computing
436        the size of patterns that contain repeated groups with explicit upper
437        limits. As the maximum quantifier is 65535, the maximum group length was
438        set at 30,000 so that the product of these two numbers did not overflow a
439        32-bit integer. However, it turns out that people want to use groups that
440        are longer than 30,000 bytes (though not repeat them that many times).
441        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
442        made it possible to implement the integer overflow checks in a much more
443        dynamic way, which I have now done. The artificial limitation on group
444        length has been removed - we now have only the limit on the total length of
445        the compiled pattern, which depends on the LINK_SIZE setting.
447    10. Fixed a bug in the documentation for get/copy named substring when
448        duplicate names are permitted. If none of the named substrings are set, the
449        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
450        empty string.
452    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
453        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
454        because the ] is interpreted as the first data character and the
455        terminating ] is not found. PCRE has been made compatible with Perl in this
456        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
457        cause memory overwriting.
459    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
460        string has been matched (to stop an infinite loop). It was not recognizing
461        a conditional subpattern that could match an empty string if that
462        subpattern was within another subpattern. For example, it looped when
463        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
464        condition was not nested. This bug has been fixed.
466    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
467        past the start of the subject in the presence of bytes with the top bit
468        set, for example "\x8aBCD".
470    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
471        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
473    14. Optimized (?!) to (*FAIL).
475    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
476        This restricts code points to be within the range 0 to 0x10FFFF, excluding
477        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
478        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
479        does: it's just the validity check that is more restrictive.
481    16. Inserted checks for integer overflows during escape sequence (backslash)
482        processing, and also fixed erroneous offset values for syntax errors during
483        backslash processing.
485    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
486        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
488    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
489        caused an overrun.
491    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
492        something other than just ASCII characters) inside a group that had an
493        unlimited repeat caused a loop at compile time (while checking to see
494        whether the group could match an empty string).
496    20. Debugging a pattern containing \p or \P could cause a crash. For example,
497        [\P{Any}] did so. (Error in the code for printing property names.)
499    21. An orphan \E inside a character class could cause a crash.
501    22. A repeated capturing bracket such as (A)? could cause a wild memory
502        reference during compilation.
504    23. There are several functions in pcre_compile() that scan along a compiled
505        expression for various reasons (e.g. to see if it's fixed length for look
506        behind). There were bugs in these functions when a repeated \p or \P was
507        present in the pattern. These operators have additional parameters compared
508        with \d, etc, and these were not being taken into account when moving along
509        the compiled data. Specifically:
511        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
512            length.
514        (b) An item such as \pL+ within a repeated group could cause crashes or
515            loops.
517        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
518            "reference to non-existent subpattern" error.
520        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
522    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
523        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
525    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
527    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
528        character were causing crashes (broken optimization).
530    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
531        \p or \P) caused a compile-time loop.
533    28. More problems have arisen in unanchored patterns when CRLF is a valid line
534        break. For example, the unstudied pattern [\r\n]A does not match the string
535        "\r\nA" because change 7.0/46 below moves the current point on by two
536        characters after failing to match at the start. However, the pattern \nA
537        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
538        the same is true. There doesn't seem any very clean way out of this, but
539        what I have chosen to do makes the common cases work: PCRE now takes note
540        of whether there can be an explicit match for \r or \n anywhere in the
541        pattern, and if so, 7.0/46 no longer applies. As part of this change,
542        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
543        pattern has explicit CR or LF references.
545    29. Added (*CR) etc for changing newline setting at start of pattern.
548    Version 7.2 19-Jun-07
549    ---------------------
551     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
552        which is apparently normally available under Windows.
554     2. Re-jig the pcregrep tests with different newline settings in an attempt
555        to make them independent of the local environment's newline setting.
557     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
559     4. Some of the "internals" tests were previously cut out when the link size
560        was not 2, because the output contained actual offsets. The recent new
561        "Z" feature of pcretest means that these can be cut out, making the tests
562        usable with all link sizes.
564     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
565        stack recursion. This gives a massive performance boost under BSD, but just
566        a small improvement under Linux. However, it saves one field in the frame
567        in all cases.
569     6. Added more features from the forthcoming Perl 5.10:
571        (a) (?-n) (where n is a string of digits) is a relative subroutine or
572            recursion call. It refers to the nth most recently opened parentheses.
574        (b) (?+n) is also a relative subroutine call; it refers to the nth next
575            to be opened parentheses.
577        (c) Conditions that refer to capturing parentheses can be specified
578            relatively, for example, (?(-2)... or (?(+3)...
580        (d) \K resets the start of the current match so that everything before
581            is not part of it.
583        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
585        (f) \g{name} is another synonym - part of Perl 5.10's unification of
586            reference syntax.
588        (g) (?| introduces a group in which the numbering of parentheses in each
589            alternative starts with the same number.
591        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
593     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
596     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
597        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
598        for detecting groups that can match an empty string.
600     9. A pattern with a very large number of alternatives (more than several
601        hundred) was running out of internal workspace during the pre-compile
602        phase, where pcre_compile() figures out how much memory will be needed. A
603        bit of new cunning has reduced the workspace needed for groups with
604        alternatives. The 1000-alternative test pattern now uses 12 bytes of
605        workspace instead of running out of the 4096 that are available.
607    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
609    11. Applied patch from Google to remove an optimization that didn't quite work.
610        The report of the bug said:
612          pcrecpp::RE("a*").FullMatch("aaa") matches, while
613          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
614          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
616    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
617        it matched the wrong number of bytes.
620    Version 7.1 24-Apr-07
621    ---------------------
623     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
624        that is more "standard", making use of automake and other Autotools. There
625        is some re-arrangement of the files and adjustment of comments consequent
626        on this.
628     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
629        for recursive directory scanning broke on some systems because the files
630        are not scanned in any specific order and on different systems the order
631        was different. A call to "sort" has been inserted into RunGrepTest for the
632        approprate test as a short-term fix. In the longer term there may be an
633        alternative.
635     3. I had an email from Eric Raymond about problems translating some of PCRE's
636        man pages to HTML (despite the fact that I distribute HTML pages, some
637        people do their own conversions for various reasons). The problems
638        concerned the use of low-level troff macros .br and .in. I have therefore
639        removed all such uses from the man pages (some were redundant, some could
640        be replaced by .nf/.fi pairs). The 132html script that I use to generate
641        HTML has been updated to handle .nf/.fi and to complain if it encounters
642        .br or .in.
644     4. Updated comments in configure.ac that get placed in config.h.in and also
645        arranged for config.h to be included in the distribution, with the name
646        config.h.generic, for the benefit of those who have to compile without
647        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
649     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
650        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
651        makevp.bat for the current PCRE, using the additional files
652        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
654     6. A Windows user reported a minor discrepancy with test 2, which turned out
655        to be caused by a trailing space on an input line that had got lost in his
656        copy. The trailing space was an accident, so I've just removed it.
658     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
659        that is needed.
661     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
662        as "const" (a) because they are and (b) because it helps the PHP
663        maintainers who have recently made a script to detect big data structures
664        in the php code that should be moved to the .rodata section. I remembered
665        to update Builducptable as well, so it won't revert if ucptable.h is ever
666        re-created.
668     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
669        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
670        order to be able to cut out the UTF-8 tables in the latter when UTF-8
671        support is not required. This saves 1.5-2K of code, which is important in
672        some applications.
674        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
675        so as not to refer to the tables, even though these functions will never be
676        called when UTF-8 support is disabled. Otherwise there are problems with a
677        shared library.
679    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
681        (a) It was defining its arguments as char * instead of void *.
683        (b) It was assuming that all moves were upwards in memory; this was true
684            a long time ago when I wrote it, but is no longer the case.
686        The emulated memove() is provided for those environments that have neither
687        memmove() nor bcopy(). I didn't think anyone used it these days, but that
688        is clearly not the case, as these two bugs were recently reported.
690    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
691        and Detrail to create the HTML documentation, the .txt form of the man
692        pages, and it removes trailing spaces from listed files. It also creates
693        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
694        case, it wraps all the #defines with #ifndefs. This script should be run
695        before "make dist".
697    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
698        with Unicode property support.
700        (a) For a maximizing quantifier, if the two different cases of the
701            character were of different lengths in their UTF-8 codings (there are
702            some cases like this - I found 11), and the matching function had to
703            back up over a mixture of the two cases, it incorrectly assumed they
704            were both the same length.
706        (b) When PCRE was configured to use the heap rather than the stack for
707            recursion during matching, it was not correctly preserving the data for
708            the other case of a UTF-8 character when checking ahead for a match
709            while processing a minimizing repeat. If the check also involved
710            matching a wide character, but failed, corruption could cause an
711            erroneous result when trying to check for a repeat of the original
712            character.
714    13. Some tidying changes to the testing mechanism:
716        (a) The RunTest script now detects the internal link size and whether there
717            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
718            values substituted by "configure". (The RunGrepTest script already did
719            this for UTF-8.) The configure.ac script no longer substitutes the
720            relevant variables.
722        (b) The debugging options /B and /D in pcretest show the compiled bytecode
723            with length and offset values. This means that the output is different
724            for different internal link sizes. Test 2 is skipped for link sizes
725            other than 2 because of this, bypassing the problem. Unfortunately,
726            there was also a test in test 3 (the locale tests) that used /B and
727            failed for link sizes other than 2. Rather than cut the whole test out,
728            I have added a new /Z option to pcretest that replaces the length and
729            offset values with spaces. This is now used to make test 3 independent
730            of link size. (Test 2 will be tidied up later.)
732    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
733        segmentation fault instead of returning the appropriate error message.
735    15. In multiline mode when the newline sequence was set to "any", the pattern
736        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
737        This doesn't seem right; it now treats the CRLF combination as the line
738        ending, and so does not match in that case. It's only a pattern such as ^$
739        that would hit this one: something like ^ABC$ would have failed after \r
740        and then tried again after \r\n.
742    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
743        in an attempt to make files that differ only in their line terminators
744        compare equal. This works on Linux.
746    17. Under certain error circumstances pcregrep might try to free random memory
747        as it exited. This is now fixed, thanks to valgrind.
749    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
750        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
751        was because its rules for how to advance for /g after matching an empty
752        string at the end of a line did not allow for this case. They now check for
753        it specially.
755    20. pcretest is supposed to handle patterns and data of any length, by
756        extending its buffers when necessary. It was getting this wrong when the
757        buffer for a data line had to be extended.
759    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
760        CRLF as a newline sequence.
762    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
763        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
764        I have nevertheless tidied it up.
766    23. Added some casts to kill warnings from HP-UX ia64 compiler.
768    24. Added a man page for pcre-config.
771    Version 7.0 19-Dec-06
772    ---------------------
774     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
775        moving to gcc 4.1.1.
777     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
778        sys/time.h, which is documented as needed for this function. It doesn't
779        seem to matter on Linux, but it showed up on some releases of OS X.
781     3. It seems that there are systems where bytes whose values are greater than
782        127 match isprint() in the "C" locale. The "C" locale should be the
783        default when a C program starts up. In most systems, only ASCII printing
784        characters match isprint(). This difference caused the output from pcretest
785        to vary, making some of the tests fail. I have changed pcretest so that:
787        (a) When it is outputting text in the compiled version of a pattern, bytes
788            other than 32-126 are always shown as hex escapes.
790        (b) When it is outputting text that is a matched part of a subject string,
791            it does the same, unless a different locale has been set for the match
792            (using the /L modifier). In this case, it uses isprint() to decide.
794     4. Fixed a major bug that caused incorrect computation of the amount of memory
795        required for a compiled pattern when options that changed within the
796        pattern affected the logic of the preliminary scan that determines the
797        length. The relevant options are -x, and -i in UTF-8 mode. The result was
798        that the computed length was too small. The symptoms of this bug were
799        either the PCRE error "internal error: code overflow" from pcre_compile(),
800        or a glibc crash with a message such as "pcretest: free(): invalid next
801        size (fast)". Examples of patterns that provoked this bug (shown in
802        pcretest format) are:
804          /(?-x: )/x
805          /(?x)(?-x: \s*#\s*)/
806          /((?i)[\x{c0}])/8
807          /(?i:[\x{c0}])/8
809        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
810        is now done differently.
812     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
813        wrapper classes; (b) implement a new function in the C++ scanner that is
814        more efficient than the old way of doing things because it avoids levels of
815        recursion in the regex matching; (c) add a paragraph to the documentation
816        for the FullMatch() function.
818     6. The escape sequence \n was being treated as whatever was defined as
819        "newline". Not only was this contrary to the documentation, which states
820        that \n is character 10 (hex 0A), but it also went horribly wrong when
821        "newline" was defined as CRLF. This has been fixed.
823     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
824        was being set to -1 for the "end of line" case (supposedly a value that no
825        character can have). Though this value is never used (the check for end of
826        line is "zero bytes in current character"), it caused compiler complaints.
827        I've changed it to 0xffffffff.
829     8. In pcre_version.c, the version string was being built by a sequence of
830        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
831        string (as it is for production releases) called a macro with an empty
832        argument. The C standard says the result of this is undefined. The gcc
833        compiler treats it as an empty string (which was what was wanted) but it is
834        reported that Visual C gives an error. The source has been hacked around to
835        avoid this problem.
837     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
838        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
839        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
840        of them did).
842    10. Originally, pcretest opened its input and output without "b"; then I was
843        told that "b" was needed in some environments, so it was added for release
844        5.0 to both the input and output. (It makes no difference on Unix-like
845        systems.) Later I was told that it is wrong for the input on Windows. I've
846        now abstracted the modes into two macros, to make it easier to fiddle with
847        them, and removed "b" from the input mode under Windows.
849    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
851    12. Added -help and --help to pcretest as an official way of being reminded
852        of the options.
854    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
855        and pcrecpp.cc because they annoy compilers at high warning levels.
857    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
859    15. Fixed an occurrence of == in configure.ac that should have been = (shell
860        scripts are not C programs :-) and which was not noticed because it works
861        on Linux.
863    16. pcretest is supposed to handle any length of pattern and data line (as one
864        line or as a continued sequence of lines) by extending its input buffer if
865        necessary. This feature was broken for very long pattern lines, leading to
866        a string of junk being passed to pcre_compile() if the pattern was longer
867        than about 50K.
869    17. I have done a major re-factoring of the way pcre_compile() computes the
870        amount of memory needed for a compiled pattern. Previously, there was code
871        that made a preliminary scan of the pattern in order to do this. That was
872        OK when PCRE was new, but as the facilities have expanded, it has become
873        harder and harder to keep it in step with the real compile phase, and there
874        have been a number of bugs (see for example, 4 above). I have now found a
875        cunning way of running the real compile function in a "fake" mode that
876        enables it to compute how much memory it would need, while actually only
877        ever using a few hundred bytes of working memory and without too many
878        tests of the mode. This should make future maintenance and development
879        easier. A side effect of this work is that the limit of 200 on the nesting
880        depth of parentheses has been removed (though this was never a serious
881        limitation, I suspect). However, there is a downside: pcre_compile() now
882        runs more slowly than before (30% or more, depending on the pattern). I
883        hope this isn't a big issue. There is no effect on runtime performance.
885    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
886        newline (only possible for the last line of a file) and it was a
887        pattern that set a locale (followed by /Lsomething), pcretest crashed.
889    19. Added additional timing features to pcretest. (1) The -tm option now times
890        matching only, not compiling. (2) Both -t and -tm can be followed, as a
891        separate command line item, by a number that specifies the number of
892        repeats to use when timing. The default is 50000; this gives better
893        precision, but takes uncomfortably long for very large patterns.
895    20. Extended pcre_study() to be more clever in cases where a branch of a
896        subpattern has no definite first character. For example, (a*|b*)[cd] would
897        previously give no result from pcre_study(). Now it recognizes that the
898        first character must be a, b, c, or d.
900    21. There was an incorrect error "recursive call could loop indefinitely" if
901        a subpattern (or the entire pattern) that was being tested for matching an
902        empty string contained only one non-empty item after a nested subpattern.
903        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
904        incorrectly, because the \d was being skipped in the check.
906    22. The pcretest program now has a new pattern option /B and a command line
907        option -b, which is equivalent to adding /B to every pattern. This causes
908        it to show the compiled bytecode, without the additional information that
909        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
910        is the same as /B/I).
912    23. A new optimization is now able automatically to treat some sequences such
913        as a*b as a*+b. More specifically, if something simple (such as a character
914        or a simple class like \d) has an unlimited quantifier, and is followed by
915        something that cannot possibly match the quantified thing, the quantifier
916        is automatically "possessified".
918    24. A recursive reference to a subpattern whose number was greater than 39
919        went wrong under certain circumstances in UTF-8 mode. This bug could also
920        have affected the operation of pcre_study().
922    25. Realized that a little bit of performance could be had by replacing
923        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
925    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
927    27. Possessive quantifiers such as a++ were previously implemented by turning
928        them into atomic groups such as ($>a+). Now they have their own opcodes,
929        which improves performance. This includes the automatically created ones
930        from 23 above.
932    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
933        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
934        the first matched character to be a colon. This applied both to named and
935        numbered groups.
937    29. The ucpinternal.h header file was missing its idempotency #ifdef.
939    30. I was sent a "project" file called libpcre.a.dev which I understand makes
940        building PCRE on Windows easier, so I have included it in the distribution.
942    31. There is now a check in pcretest against a ridiculously large number being
943        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
944        loop, the loop is abandoned.
946    32. Forward references to subpatterns in conditions such as (?(2)...) where
947        subpattern 2 is defined later cause pcre_compile() to search forwards in
948        the pattern for the relevant set of parentheses. This search went wrong
949        when there were unescaped parentheses in a character class, parentheses
950        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
952    33. "Subroutine" calls and backreferences were previously restricted to
953        referencing subpatterns earlier in the regex. This restriction has now
954        been removed.
956    34. Added a number of extra features that are going to be in Perl 5.10. On the
957        whole, these are just syntactic alternatives for features that PCRE had
958        previously implemented using the Python syntax or my own invention. The
959        other formats are all retained for compatibility.
961        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
962            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
963            also .NET compatible.
965        (b) A recursion or subroutine call to a named group can now be defined as
966            (?&name) as well as (?P>name).
968        (c) A backreference to a named group can now be defined as \k<name> or
969            \k'name' as well as (?P=name). The new forms, as well as being in Perl
970            5.10, are also .NET compatible.
972        (d) A conditional reference to a named group can now use the syntax
973            (?(<name>) or (?('name') as well as (?(name).
975        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
976            groups (named and numbered) that are never evaluated inline, but can be
977            called as "subroutines" from elsewhere. In effect, the DEFINE condition
978            is always false. There may be only one alternative in such a group.
980        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
981            as the simple (?(R). The condition is true only if the most recent
982            recursion is that of the given number or name. It does not search out
983            through the entire recursion stack.
985        (g) The escape \gN or \g{N} has been added, where N is a positive or
986            negative number, specifying an absolute or relative reference.
988    35. Tidied to get rid of some further signed/unsigned compiler warnings and
989        some "unreachable code" warnings.
991    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
992        things, this adds five new scripts.
994    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
995        There were also incompatibilities regarding the handling of \Q..\E inside
996        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
997        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
999    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
1000        matches an empty string, and forcibly breaks the loop. There were bugs in
1001        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
1002        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
1003        separate and independent bugs (that affected different cases) have been
1004        fixed.
1006    39. Refactored the code to abolish the use of different opcodes for small
1007        capturing bracket numbers. This is a tidy that I avoided doing when I
1008        removed the limit on the number of capturing brackets for 3.5 back in 2001.
1009        The new approach is not only tidier, it makes it possible to reduce the
1010        memory needed to fix the previous bug (38).
1012    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
1013        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
1014        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
1015        mode.
1017    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
1018        report.
1020    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
1021        copy construction and assignment in the C++ wrapper.
1023    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
1024        couple of bugs that could have given wrong results in the "--newline=crlf"
1025        case.
1027    44. Added a number of casts and did some reorganization of signed/unsigned int
1028        variables following suggestions from Dair Grant. Also renamed the variable
1029        "this" as "item" because it is a C++ keyword.
1031    45. Arranged for dftables to add
1033          #include "pcre_internal.h"
1035        to pcre_chartables.c because without it, gcc 4.x may remove the array
1036        definition from the final binary if PCRE is built into a static library and
1037        dead code stripping is activated.
1039    46. For an unanchored pattern, if a match attempt fails at the start of a
1040        newline sequence, and the newline setting is CRLF or ANY, and the next two
1041        characters are CRLF, advance by two characters instead of one.
1044    Version 6.7 04-Jul-06
1045    ---------------------
1047     1. In order to handle tests when input lines are enormously long, pcretest has
1048        been re-factored so that it automatically extends its buffers when
1049        necessary. The code is crude, but this _is_ just a test program. The
1050        default size has been increased from 32K to 50K.
1052     2. The code in pcre_study() was using the value of the re argument before
1053        testing it for NULL. (Of course, in any sensible call of the function, it
1054        won't be NULL.)
1056     3. The memmove() emulation function in pcre_internal.h, which is used on
1057        systems that lack both memmove() and bcopy() - that is, hardly ever -
1058        was missing a "static" storage class specifier.
1060     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1061        containing an extended class (one that cannot be represented by a bitmap
1062        because it contains high-valued characters or Unicode property items, e.g.
1063        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1064        pattern, but PCRE should not loop if you do not (it no longer does).
1065        [Detail: two cases were found: (a) a repeated subpattern containing an
1066        extended class; (b) a recursive reference to a subpattern that followed a
1067        previous extended class. It wasn't skipping over the extended class
1068        correctly when UTF-8 mode was not set.]
1070     5. A negated single-character class was not being recognized as fixed-length
1071        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1072        compile error "lookbehind assertion is not fixed length".
1074     6. The RunPerlTest auxiliary script was showing an unexpected difference
1075        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1076        write a Perl script that can interpret lines of an input file either as
1077        byte characters or as UTF-8, which is what "perltest" was being required to
1078        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1079        can't do is switch easily at run time between having the "use utf8;" pragma
1080        or not. In the end, I fudged it by using the RunPerlTest script to insert
1081        "use utf8;" explicitly for the UTF-8 tests.
1083     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1084        the end of the subject string, contrary to the documentation and to what
1085        Perl does. This was true of both matching functions. Now it matches only at
1086        the start of the subject and immediately after *internal* newlines.
1088     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1089        a pointer to an int instead of a pointer to an unsigned long int. This
1090        caused problems on 64-bit systems.
1092     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1093        instance of the 'standard' template library not being so standard".
1095    10. There was no check on the number of named subpatterns nor the maximum
1096        length of a subpattern name. The product of these values is used to compute
1097        the size of the memory block for a compiled pattern. By supplying a very
1098        long subpattern name and a large number of named subpatterns, the size
1099        computation could be caused to overflow. This is now prevented by limiting
1100        the length of names to 32 characters, and the number of named subpatterns
1101        to 10,000.
1103    11. Subpatterns that are repeated with specific counts have to be replicated in
1104        the compiled pattern. The size of memory for this was computed from the
1105        length of the subpattern and the repeat count. The latter is limited to
1106        65535, but there was no limit on the former, meaning that integer overflow
1107        could in principle occur. The compiled length of a repeated subpattern is
1108        now limited to 30,000 bytes in order to prevent this.
1110    12. Added the optional facility to have named substrings with the same name.
1112    13. Added the ability to use a named substring as a condition, using the
1113        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1114        are numbers (not recommended). Forward references are permitted.
1116    14. Added forward references in named backreferences (if you see what I mean).
1118    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1119        pattern could run off the end of the subject. For example, the pattern
1120        "(?s)(.{1,5})"8 did this with the subject "ab".
1122    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1123        PCRE_CASELESS was set when matching characters that were quantified with ?
1124        or *.
1126    17. A character class other than a single negated character that had a minimum
1127        but no maximum quantifier - for example [ab]{6,} - was not handled
1128        correctly by pce_dfa_exec(). It would match only one character.
1130    18. A valid (though odd) pattern that looked like a POSIX character
1131        class but used an invalid character after [ (for example [[,abc,]]) caused
1132        pcre_compile() to give the error "Failed: internal error: code overflow" or
1133        in some cases to crash with a glibc free() error. This could even happen if
1134        the pattern terminated after [[ but there just happened to be a sequence of
1135        letters, a binary zero, and a closing ] in the memory that followed.
1137    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1138        over the years. Originally (before any Unicode support), just the bottom 8
1139        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1140        output from "man perlunicode" includes this:
1142          The regular expression compiler produces polymorphic opcodes.  That
1143          is, the pattern adapts to the data and automatically switches to
1144          the Unicode character scheme when presented with Unicode data--or
1145          instead uses a traditional byte scheme when presented with byte
1146          data.
1148        Sadly, a wide octal escape does not cause a switch, and in a string with
1149        no other multibyte characters, these octal escapes are treated as before.
1150        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1151        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1152        Unicode string.
1154        I have not perpetrated such confusion in PCRE. Up till now, it took just
1155        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1156        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1157        translate to the appropriate multibyte character.
1159    29. Applied some refactoring to reduce the number of warnings from Microsoft
1160        and Borland compilers. This has included removing the fudge introduced
1161        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1162        a warning about an unused variable.
1164    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1165        characters since release 4.0, because Perl (from release 5.004) does not.
1166        [Or at least, is documented not to: some releases seem to be in conflict
1167        with the documentation.] However, when a pattern was studied with
1168        pcre_study() and all its branches started with \s, PCRE still included VT
1169        as a possible starting character. Of course, this did no harm; it just
1170        caused an unnecessary match attempt.
1172    22. Removed a now-redundant internal flag bit that recorded the fact that case
1173        dependency changed within the pattern. This was once needed for "required
1174        byte" processing, but is no longer used. This recovers a now-scarce options
1175        bit. Also moved the least significant internal flag bit to the most-
1176        significant bit of the word, which was not previously used (hangover from
1177        the days when it was an int rather than a uint) to free up another bit for
1178        the future.
1180    23. Added support for CRLF line endings as well as CR and LF. As well as the
1181        default being selectable at build time, it can now be changed at runtime
1182        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1183        specify that it is scanning data with non-default line endings.
1185    24. Changed the definition of CXXLINK to make it agree with the definition of
1186        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1188    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1189        recursions. This makes a big different to stack usage for some patterns.
1191    26. If a subpattern containing a named recursion or subroutine reference such
1192        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1193        the space required for the compiled pattern went wrong and gave too small a
1194        value. Depending on the environment, this could lead to "Failed: internal
1195        error: code overflow at offset 49" or "glibc detected double free or
1196        corruption" errors.
1198    27. Applied patches from Google (a) to support the new newline modes and (b) to
1199        advance over multibyte UTF-8 characters in GlobalReplace.
1201    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1202        difference for some implementation of PCRE in some Windows version.
1204    29. Added some extra testing facilities to pcretest:
1206        \q<number>   in a data line sets the "match limit" value
1207        \Q<number>   in a data line sets the "match recursion limt" value
1208        -S <number>  sets the stack size, where <number> is in megabytes
1210        The -S option isn't available for Windows.
1213    Version 6.6 06-Feb-06
1214    ---------------------
1216     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1217        in pcreposix.h. I have copied the definition from pcre.h.
1219     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1220        because pcre.h is no longer a built file.
1222     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1223        not normally included in the compiled code.
1226    Version 6.5 01-Feb-06
1227    ---------------------
1229     1. When using the partial match feature with pcre_dfa_exec(), it was not
1230        anchoring the second and subsequent partial matches at the new starting
1231        point. This could lead to incorrect results. For example, with the pattern
1232        /1234/, partially matching against "123" and then "a4" gave a match.
1234     2. Changes to pcregrep:
1236        (a) All non-match returns from pcre_exec() were being treated as failures
1237            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1238            error message is output. Some extra information is given for the
1239            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1240            probably the only errors that are likely to be caused by users (by
1241            specifying a regex that has nested indefinite repeats, for instance).
1242            If there are more than 20 of these errors, pcregrep is abandoned.
1244        (b) A binary zero was treated as data while matching, but terminated the
1245            output line if it was written out. This has been fixed: binary zeroes
1246            are now no different to any other data bytes.
1248        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1249            used to set a locale for matching. The --locale=xxxx long option has
1250            been added (no short equivalent) to specify a locale explicitly on the
1251            pcregrep command, overriding the environment variables.
1253        (d) When -B was used with -n, some line numbers in the output were one less
1254            than they should have been.
1256        (e) Added the -o (--only-matching) option.
1258        (f) If -A or -C was used with -c (count only), some lines of context were
1259            accidentally printed for the final match.
1261        (g) Added the -H (--with-filename) option.
1263        (h) The combination of options -rh failed to suppress file names for files
1264            that were found from directory arguments.
1266        (i) Added the -D (--devices) and -d (--directories) options.
1268        (j) Added the -F (--fixed-strings) option.
1270        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1272        (l) Added the --colo(u)r option.
1274        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1275            is not present by default.
1277     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1278        items such as (?R) or (?1), when the recursion could match a number of
1279        alternatives. If it matched one of the alternatives, but subsequently,
1280        outside the recursion, there was a failure, the code tried to back up into
1281        the recursion. However, because of the way PCRE is implemented, this is not
1282        possible, and the result was an incorrect result from the match.
1284        In order to prevent this happening, the specification of recursion has
1285        been changed so that all such subpatterns are automatically treated as
1286        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1288     4. I had overlooked the fact that, in some locales, there are characters for
1289        which isalpha() is true but neither isupper() nor islower() are true. In
1290        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1291        and ordfeminine) are like this. This affected the treatment of \w and \W
1292        when they appeared in character classes, but not when they appeared outside
1293        a character class. The bit map for "word" characters is now created
1294        separately from the results of isalnum() instead of just taking it from the
1295        upper, lower, and digit maps. (Plus the underscore character, of course.)
1297     5. The above bug also affected the handling of POSIX character classes such as
1298        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1299        permanent tables. Instead, the bit maps for such a class were previously
1300        created as the appropriate unions of the upper, lower, and digit bitmaps.
1301        Now they are created by subtraction from the [[:word:]] class, which has
1302        its own bitmap.
1304     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1305        It is created by subtracting the vertical space characters (\x09, \x0a,
1306        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1307        subtraction was done in the overall bitmap for a character class, meaning
1308        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1309        be recognized. This bug has been fixed.
1311     7. Patches from the folks at Google:
1313          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1314          real life, but is still worth protecting against".
1316          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1317          regular expressions".
1319          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1320          have it.
1322          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1323          "configure" and the latter not, in order to fix a problem somebody had
1324          with compiling the Arg class on HP-UX.
1326          (e) Improve the error-handling of the C++ wrapper a little bit.
1328          (f) New tests for checking recursion limiting.
1330     8. The pcre_memmove() function, which is used only if the environment does not
1331        have a standard memmove() function (and is therefore rarely compiled),
1332        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1333        returning a result (though PCRE never actually uses the result).
1335     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1336        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1337        returned instead of calling malloc() with an overflowing number that would
1338        most likely cause subsequent chaos.
1340    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1342    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1343        with this option is matched, the nmatch and pmatch options of regexec() are
1344        ignored.
1346    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1347        provided in case anyone wants to the the POSIX interface with UTF-8
1348        strings.
1350    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1351        C++ linking (needed for some HP-UX environments).
1353    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1354        (unused parameter) and in the pcre_printint() function (omitted "default"
1355        switch label when the default is to do nothing).
1357    15. Added some code to make it possible, when PCRE is compiled as a C++
1358        library, to replace subject pointers for pcre_exec() with a smart pointer
1359        class, thus making it possible to process discontinuous strings.
1361    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1362        much the same function. They were added by different people who were trying
1363        to make PCRE easy to compile on non-Unix systems. It has been suggested
1364        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1365        for compiling on Windows systems. I have therefore replaced it with
1366        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1367        defaults to "extern" for C or "extern C" for C++, which works fine on
1368        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1369        SCOPE with something explicit in config.h. In addition:
1371        (a) pcreposix.h still had just "extern" instead of either of these macros;
1372            I have replaced it with PCRE_DATA_SCOPE.
1374        (b) Functions such as _pcre_xclass(), which are internal to the library,
1375            but external in the C sense, all had PCRE_EXPORT in their definitions.
1376            This is apparently wrong for the Windows case, so I have removed it.
1377            (It makes no difference on Unix-like systems.)
1379    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1380        of recursive calls to match(). This is different to MATCH_LIMIT because
1381        that limits the total number of calls to match(), not all of which increase
1382        the depth of recursion. Limiting the recursion depth limits the amount of
1383        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1384        when PCRE is compiled, and changed at run time. A patch from Google adds
1385        this functionality to the C++ interface.
1387    18. Changes to the handling of Unicode character properties:
1389        (a) Updated the table to Unicode 4.1.0.
1391        (b) Recognize characters that are not in the table as "Cn" (undefined).
1393        (c) I revised the way the table is implemented to a much improved format
1394            which includes recognition of ranges. It now supports the ranges that
1395            are defined in UnicodeData.txt, and it also amalgamates other
1396            characters into ranges. This has reduced the number of entries in the
1397            table from around 16,000 to around 3,000, thus reducing its size
1398            considerably. I realized I did not need to use a tree structure after
1399            all - a binary chop search is just as efficient. Having reduced the
1400            number of entries, I extended their size from 6 bytes to 8 bytes to
1401            allow for more data.
1403        (d) Added support for Unicode script names via properties such as \p{Han}.
1405    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1406        matching that character.
1408    20. When matching a repeated Unicode property with a minimum greater than zero,
1409        (for example \pL{2,}), PCRE could look past the end of the subject if it
1410        reached it while seeking the minimum number of characters. This could
1411        happen only if some of the characters were more than one byte long, because
1412        there is a check for at least the minimum number of bytes.
1414    21. Refactored the implementation of \p and \P so as to be more general, to
1415        allow for more different types of property in future. This has changed the
1416        compiled form incompatibly. Anybody with saved compiled patterns that use
1417        \p or \P will have to recompile them.
1419    22. Added "Any" and "L&" to the supported property types.
1421    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1422        but give a compile time error if the value is greater than 0xff.
1424    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1425        accidentally not being installed or uninstalled.
1427    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1428        made were to insert the current release number. This seemed silly, because
1429        it made things harder for people building PCRE on systems that don't run
1430        "configure". I have turned pcre.h into a distributed file, no longer built
1431        by "configure", with the version identification directly included. There is
1432        no longer a pcre.h.in file.
1434        However, this change necessitated a change to the pcre-config script as
1435        well. It is built from pcre-config.in, and one of the substitutions was the
1436        release number. I have updated configure.ac so that ./configure now finds
1437        the release number by grepping pcre.h.
1439    26. Added the ability to run the tests under valgrind.
1442    Version 6.4 05-Sep-05
1443    ---------------------
1445     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1446        "--" to be printed when multiple files were scanned, even when none of the
1447        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1448        consider it to be a bug, and have restored the previous behaviour.
1450     2. A couple of code tidies to get rid of compiler warnings.
1452     3. The pcretest program used to cheat by referring to symbols in the library
1453        whose names begin with _pcre_. These are internal symbols that are not
1454        really supposed to be visible externally, and in some environments it is
1455        possible to suppress them. The cheating is now confined to including
1456        certain files from the library's source, which is a bit cleaner.
1458     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1459        file's purpose clearer.
1461     5. Reorganized pcre_ucp_findchar().
1464    Version 6.3 15-Aug-05
1465    ---------------------
1467     1. The file libpcre.pc.in did not have general read permission in the tarball.
1469     2. There were some problems when building without C++ support:
1471        (a) If C++ support was not built, "make install" and "make test" still
1472            tried to test it.
1474        (b) There were problems when the value of CXX was explicitly set. Some
1475            changes have been made to try to fix these, and ...
1477        (c) --disable-cpp can now be used to explicitly disable C++ support.
1479        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1480            backslash in a target when C++ was disabled. This confuses some
1481            versions of "make", apparently. Using an intermediate variable solves
1482            this. (Same for CPP_LOBJ.)
1484     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1485        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1486        necessary on certain architectures.
1488     4. Added a setting of -export-symbols-regex to the link command to remove
1489        those symbols that are exported in the C sense, but actually are local
1490        within the library, and not documented. Their names all begin with
1491        "_pcre_". This is not a perfect job, because (a) we have to except some
1492        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1493        available (and never for static libraries). I have made a note to try to
1494        find a way round (a) in the future.
1497    Version 6.2 01-Aug-05
1498    ---------------------
1500     1. There was no test for integer overflow of quantifier values. A construction
1501        such as {1111111111111111} would give undefined results. What is worse, if
1502        a minimum quantifier for a parenthesized subpattern overflowed and became
1503        negative, the calculation of the memory size went wrong. This could have
1504        led to memory overwriting.
1506     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1508     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1509        operating environments where this matters.
1511     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1512        PCRE options from within the C++ wrapper.
1514     5. Named capturing subpatterns were not being correctly counted when a pattern
1515        was compiled. This caused two problems: (a) If there were more than 100
1516        such subpatterns, the calculation of the memory needed for the whole
1517        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1518        back references of the form \12, where the number was greater than 9, were
1519        not recognized as back references, even though there were sufficient
1520        previous subpatterns.
1522     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1523        versions of gcc, e.g. 2.95.4.
1526    Version 6.1 21-Jun-05
1527    ---------------------
1529     1. There was one reference to the variable "posix" in pcretest.c that was not
1530        surrounded by "#if !defined NOPOSIX".
1532     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1533        the cross-check on the old pcre_info() function, for the benefit of the
1534        cut-down version of PCRE that is currently imported into Exim.
1536     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1537        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1538        patterns that start (?i) but I don't think that matters. The use of (?i) is
1539        just an example; this all applies to the other options as well.
1541     4. Since libtool seems to echo the compile commands it is issuing, the output
1542        from "make" can be reduced a bit by putting "@" in front of each libtool
1543        compile command.
1545     5. Patch from the folks at Google for configure.in to be a bit more thorough
1546        in checking for a suitable C++ installation before trying to compile the
1547        C++ stuff. This should fix a reported problem when a compiler was present,
1548        but no suitable headers.
1550     6. The man pages all had just "PCRE" as their title. I have changed them to
1551        be the relevant file name. I have also arranged that these names are
1552        retained in the file doc/pcre.txt, which is a concatenation in text format
1553        of all the man pages except the little individual ones for each function.
1555     7. The NON-UNIX-USE file had not been updated for the different set of source
1556        files that come with release 6. I also added a few comments about the C++
1557        wrapper.
1560    Version 6.0 07-Jun-05
1561    ---------------------
1563     1. Some minor internal re-organization to help with my DFA experiments.
1565     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1566        didn't matter for the library itself when fully configured, but did matter
1567        when compiling without UCP support, or within Exim, where the ucp files are
1568        not imported.
1570     3. Refactoring of the library code to split up the various functions into
1571        different source modules. The addition of the new DFA matching code (see
1572        below) to a single monolithic source would have made it really too
1573        unwieldy, quite apart from causing all the code to be include in a
1574        statically linked application, when only some functions are used. This is
1575        relevant even without the DFA addition now that patterns can be compiled in
1576        one application and matched in another.
1578        The downside of splitting up is that there have to be some external
1579        functions and data tables that are used internally in different modules of
1580        the library but which are not part of the API. These have all had their
1581        names changed to start with "_pcre_" so that they are unlikely to clash
1582        with other external names.
1584     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1585        a different (DFA) algorithm. Although it is slower than the original
1586        function, it does have some advantages for certain types of matching
1587        problem.
1589     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1590        including restarting after a partial match.
1592     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1593        defined when compiling for Windows was sent to me. I have put it into the
1594        code, though I have no means of testing or verifying it.
1596     7. Added the pcre_refcount() auxiliary function.
1598     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1599        match before or at the first newline in the subject string. In pcretest,
1600        the /f option on a pattern can be used to set this.
1602     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1603        would behave wrongly. This has been present in PCRE since release 4.0.
1605    10. A number of changes to the pcregrep command:
1607        (a) Refactored how -x works; insert ^(...)$ instead of setting
1608            PCRE_ANCHORED and checking the length, in preparation for adding
1609            something similar for -w.
1611        (b) Added the -w (match as a word) option.
1613        (c) Refactored the way lines are read and buffered so as to have more
1614            than one at a time available.
1616        (d) Implemented a pcregrep test script.
1618        (e) Added the -M (multiline match) option. This allows patterns to match
1619            over several lines of the subject. The buffering ensures that at least
1620            8K, or the rest of the document (whichever is the shorter) is available
1621            for matching (and similarly the previous 8K for lookbehind assertions).
1623        (f) Changed the --help output so that it now says
1625              -w, --word-regex(p)
1627            instead of two lines, one with "regex" and the other with "regexp"
1628            because that confused at least one person since the short forms are the
1629            same. (This required a bit of code, as the output is generated
1630            automatically from a table. It wasn't just a text change.)
1632        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1633            option but starts with a hyphen. Could be a pattern or a path name
1634            starting with a hyphen, for instance.
1636        (h) "-" can be given as a file name to represent stdin.
1638        (i) When file names are being printed, "(standard input)" is used for
1639            the standard input, for compatibility with GNU grep. Previously
1640            "<stdin>" was used.
1642        (j) The option --label=xxx can be used to supply a name to be used for
1643            stdin when file names are being printed. There is no short form.
1645        (k) Re-factored the options decoding logic because we are going to add
1646            two more options that take data. Such options can now be given in four
1647            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1649        (l) Added the -A, -B, and -C options for requesting that lines of context
1650            around matches be printed.
1652        (m) Added the -L option to print the names of files that do not contain
1653            any matching lines, that is, the complement of -l.
1655        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1656            continue to scan other files.
1658        (o) The -s option was incorrectly implemented. For compatibility with other
1659            greps, it now suppresses the error message for a non-existent or non-
1660            accessible file (but not the return code). There is a new option called
1661            -q that suppresses the output of matching lines, which was what -s was
1662            previously doing.
1664        (p) Added --include and --exclude options to specify files for inclusion
1665            and exclusion when recursing.
1667    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1668        Hopefully, it now does.
1670    12. Missing cast in pcre_study().
1672    13. Added an "uninstall" target to the makefile.
1674    14. Replaced "extern" in the function prototypes in Makefile.in with
1675        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1676        world, but is set differently for Windows.
1678    15. Added a second compiling function called pcre_compile2(). The only
1679        difference is that it has an extra argument, which is a pointer to an
1680        integer error code. When there is a compile-time failure, this is set
1681        non-zero, in addition to the error test pointer being set to point to an
1682        error message. The new argument may be NULL if no error number is required
1683        (but then you may as well call pcre_compile(), which is now just a
1684        wrapper). This facility is provided because some applications need a
1685        numeric error indication, but it has also enabled me to tidy up the way
1686        compile-time errors are handled in the POSIX wrapper.
1688    16. Added VPATH=.libs to the makefile; this should help when building with one
1689        prefix path and installing with another. (Or so I'm told by someone who
1690        knows more about this stuff than I do.)
1692    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1693        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1694        match everything, including newlines. This is not POSIX-compatible, but
1695        somebody wanted the feature. From pcretest it can be activated by using
1696        both the P and the s flags.
1698    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1700    19. libpcre.pc was being incorrectly installed as executable.
1702    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1703        it now also looks for '\r' so that it will work unmodified on Windows.
1705    21. Added Google's contributed C++ wrapper to the distribution.
1707    22. Added some untidy missing memory free() calls in pcretest, to keep
1708        Electric Fence happy when testing.
1712    Version 5.0 13-Sep-04
1713    ---------------------
1715     1. Internal change: literal characters are no longer packed up into items
1716        containing multiple characters in a single byte-string. Each character
1717        is now matched using a separate opcode. However, there may be more than one
1718        byte in the character in UTF-8 mode.
1720     2. The pcre_callout_block structure has two new fields: pattern_position and
1721        next_item_length. These contain the offset in the pattern to the next match
1722        item, and its length, respectively.
1724     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1725        insertion of callouts before each pattern item. Added the /C option to
1726        pcretest to make use of this.
1728     4. On the advice of a Windows user, the lines
1730          #if defined(_WIN32) || defined(WIN32)
1731          _setmode( _fileno( stdout ), 0x8000 );
1732          #endif  /* defined(_WIN32) || defined(WIN32) */
1734        have been added to the source of pcretest. This apparently does useful
1735        magic in relation to line terminators.
1737     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1738        for the benefit of those environments where the "b" makes a difference.
1740     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1741        to know about it. I have put a hack into configure.in that adds in code
1742        to set GCC=yes if CC=icc. This seems to end up at a point in the
1743        generated configure script that is early enough to affect the setting of
1744        compiler options, which is what is needed, but I have no means of testing
1745        whether it really works. (The user who reported this had patched the
1746        generated configure script, which of course I cannot do.)
1748        LATER: After change 22 below (new libtool files), the configure script
1749        seems to know about icc (and also ecc). Therefore, I have commented out
1750        this hack in configure.in.
1752     7. Added support for pkg-config (2 patches were sent in).
1754     8. Negated POSIX character classes that used a combination of internal tables
1755        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1756        [[:^ascii]]. Typically, they would match almost any characters. The other
1757        POSIX classes were not broken in this way.
1759     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1760        to find the match, as PCRE was deluded into thinking that the match had to
1761        start at the start point or following a newline. The same bug applied to
1762        patterns with negative forward assertions or any backward assertions
1763        preceding ".*" at the start, unless the pattern required a fixed first
1764        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1766    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1767        starting at the last subject character, bytes beyond the end of the subject
1768        string were read.
1770    11. Renamed the variable "class" as "classbits" to make life easier for C++
1771        users. (Previously there was a macro definition, but it apparently wasn't
1772        enough.)
1774    12. Added the new field "tables" to the extra data so that tables can be passed
1775        in at exec time, or the internal tables can be re-selected. This allows
1776        a compiled regex to be saved and re-used at a later time by a different
1777        program that might have everything at different addresses.
1779    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1780        -R library as well as a -L library.
1782    14. The debugging options of pcretest (-d on the command line or D on a
1783        pattern) showed incorrect output for anything following an extended class
1784        that contained multibyte characters and which was followed by a quantifier.
1786    15. Added optional support for general category Unicode character properties
1787        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1788        support. It adds about 90K to the size of the library. The meanings of the
1789        inbuilt class escapes such as \d and \s have NOT been changed.
1791    16. Updated pcredemo.c to include calls to free() to release the memory for the
1792        compiled pattern.
1794    17. The generated file chartables.c was being created in the source directory
1795        instead of in the building directory. This caused the build to fail if the
1796        source directory was different from the building directory, and was
1797        read-only.
1799    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1800        file. No doubt somebody will tell me if they don't make sense... Also added
1801        Dan Mooney's comments about building on OpenVMS.
1803    19. Added support for partial matching via the PCRE_PARTIAL option for
1804        pcre_exec() and the \P data escape in pcretest.
1806    20. Extended pcretest with 3 new pattern features:
1808        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1809              write the compiled pattern to the file whose name is "rest-of-line".
1810              This is a straight binary dump of the data, with the saved pointer to
1811              the character tables forced to be NULL. The study data, if any, is
1812              written too. After writing, pcretest reads a new pattern.
1814        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1815              compiled pattern from the given file. There must not be any
1816              occurrences of "<" in the file name (pretty unlikely); if there are,
1817              pcretest will instead treat the initial "<" as a pattern delimiter.
1818              After reading in the pattern, pcretest goes on to read data lines as
1819              usual.
1821        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1822              and 16-bit fields in a compiled pattern, to simulate a pattern that
1823              was compiled on a host of opposite endianness.
1825    21. The pcre-exec() function can now cope with patterns that were compiled on
1826        hosts of opposite endianness, with this restriction:
1828          As for any compiled expression that is saved and used later, the tables
1829          pointer field cannot be preserved; the extra_data field in the arguments
1830          to pcre_exec() should be used to pass in a tables address if a value
1831          other than the default internal tables were used at compile time.
1833    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1834        now diagnosed as an error. Previously, most of the time, a negative number
1835        would have been treated as zero, but if in addition "ovector" was passed as
1836        NULL, a crash could occur.
1838    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1839        new versions from the libtool 1.5 distribution (the last one is a copy of
1840        a file called libtool.m4). This seems to have fixed the need to patch
1841        "configure" to support Darwin 1.3 (which I used to do). However, I still
1842        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1843        workstation).
1845    24. Changed the PCRE licence to be the more standard "BSD" licence.
1848    Version 4.5 01-Dec-03
1849    ---------------------
1851     1. There has been some re-arrangement of the code for the match() function so
1852        that it can be compiled in a version that does not call itself recursively.
1853        Instead, it keeps those local variables that need separate instances for
1854        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1855        needs to "recurse". Keeping track of where control must go is done by means
1856        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1857        hide most of the details from the main code, and operates only if
1858        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1859        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1860        operating.
1862        To make it easier for callers to provide specially tailored get/free
1863        functions for this usage, two new functions, pcre_stack_malloc, and
1864        pcre_stack_free, are used. They are always called in strict stacking order,
1865        and the size of block requested is always the same.
1867        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1868        PCRE has been compiled to use the stack or the heap for recursion. The
1869        -C option of pcretest uses this to show which version is compiled.
1871        A new data escape \S, is added to pcretest; it causes the amounts of store
1872        obtained and freed by both kinds of malloc/free at match time to be added
1873        to the output.
1875     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1876        what's available on my current Linux desktop machine.
1878     3. When matching a UTF-8 string, the test for a valid string at the start has
1879        been extended. If start_offset is not zero, PCRE now checks that it points
1880        to a byte that is the start of a UTF-8 character. If not, it returns
1881        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1882        this is necessary because there may be backward assertions in the pattern.
1883        When matching the same subject several times, it may save resources to use
1884        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1886     4. The code for checking the validity of UTF-8 strings has been tightened so
1887        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1888        containing "overlong sequences".
1890     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1891        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1892        should have been "&", but it just so happened that all the cases this let
1893        through by mistake were picked up later in the function.
1895     6. I had used a variable called "isblank" - this is a C99 function, causing
1896        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1898     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1899        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1900        so the version is shown; (c) stop "make test" echoing "./RunTest".
1902     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1904     9. The prototype for memmove() for systems that don't have it was using
1905        size_t, but the inclusion of the header that defines size_t was later. I've
1906        moved the #includes for the C headers earlier to avoid this.
1908    10. Added some adjustments to the code to make it easier to compiler on certain
1909        special systems:
1911          (a) Some "const" qualifiers were missing.
1912          (b) Added the macro EXPORT before all exported functions; by default this
1913              is defined to be empty.
1914          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1915              that it reads its output file name as an argument instead of writing
1916              to the standard output and assuming this can be redirected.
1918    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1919        class containing characters with values greater than 255, PCRE compilation
1920        went into a loop.
1922    12. A recursive reference to a subpattern that was within another subpattern
1923        that had a minimum quantifier of zero caused PCRE to crash. For example,
1924        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1925        recursion. If the recursively-called subpattern itself had a zero repeat,
1926        that was OK.
1928    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1929        buffer into which it was copied (for escape processing) was still set at
1930        1024, so long lines caused crashes.
1932    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1933        "internal error: code overflow...". This applied to any character class
1934        that was followed by a possessive quantifier.
1936    15. Modified the Makefile to add libpcre.la as a prerequisite for
1937        libpcreposix.la because I was told this is needed for a parallel build to
1938        work.
1940    16. If a pattern that contained .* following optional items at the start was
1941        studied, the wrong optimizing data was generated, leading to matching
1942        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1943        matching string must start with a or b or c. The correct conclusion for
1944        this pattern is that a match can start with any character.
1947    Version 4.4 13-Aug-03
1948    ---------------------
1950     1. In UTF-8 mode, a character class containing characters with values between
1951        127 and 255 was not handled correctly if the compiled pattern was studied.
1952        In fixing this, I have also improved the studying algorithm for such
1953        classes (slightly).
1955     2. Three internal functions had redundant arguments passed to them. Removal
1956        might give a very teeny performance improvement.
1958     3. Documentation bug: the value of the capture_top field in a callout is *one
1959        more than* the number of the hightest numbered captured substring.
1961     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1962        in incorrectly linking with a previously installed version. They now link
1963        explicitly with libpcre.la.
1965     5. configure.in no longer needs to recognize Cygwin specially.
1967     6. A problem in pcre.in for Windows platforms is fixed.
1969     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1970        pcretest, it used to include the size of the study block as part of its
1971        output. Unfortunately, the structure contains a field that has a different
1972        size on different hardware architectures. This meant that the tests that
1973        showed this size failed. As the block is currently always of a fixed size,
1974        this information isn't actually particularly useful in pcretest output, so
1975        I have just removed it.
1977     8. Three pre-processor statements accidentally did not start in column 1.
1978        Sadly, there are *still* compilers around that complain, even though
1979        standard C has not required this for well over a decade. Sigh.
1981     9. In pcretest, the code for checking callouts passed small integers in the
1982        callout_data field, which is a void * field. However, some picky compilers
1983        complained about the casts involved for this on 64-bit systems. Now
1984        pcretest passes the address of the small integer instead, which should get
1985        rid of the warnings.
1987    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1988        both compile and run time, and gives an error if an invalid UTF-8 sequence
1989        is found. There is a option for disabling this check in cases where the
1990        string is known to be correct and/or the maximum performance is wanted.
1992    11. In response to a bug report, I changed one line in Makefile.in from
1994            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1995        to
1996            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1998        to look similar to other lines, but I have no way of telling whether this
1999        is the right thing to do, as I do not use Windows. No doubt I'll get told
2000        if it's wrong...
2003    Version 4.3 21-May-03
2004    ---------------------
2006    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
2007       Makefile.
2009    2. Some refactoring to improve the quality of the code:
2011       (i)   The utf8_table... variables are now declared "const".
2013       (ii)  The code for \cx, which used the "case flipping" table to upper case
2014             lower case letters, now just substracts 32. This is ASCII-specific,
2015             but the whole concept of \cx is ASCII-specific, so it seems
2016             reasonable.
2018       (iii) PCRE was using its character types table to recognize decimal and
2019             hexadecimal digits in the pattern. This is silly, because it handles
2020             only 0-9, a-f, and A-F, but the character types table is locale-
2021             specific, which means strange things might happen. A private
2022             table is now used for this - though it costs 256 bytes, a table is
2023             much faster than multiple explicit tests. Of course, the standard
2024             character types table is still used for matching digits in subject
2025             strings against \d.
2027       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
2028             ending in _t are). So I've renamed it as ESC_tee.
2030    3. The first argument for regexec() in the POSIX wrapper should have been
2031       defined as "const".
2033    4. Changed pcretest to use malloc() for its buffers so that they can be
2034       Electric Fenced for debugging.
2036    5. There were several places in the code where, in UTF-8 mode, PCRE would try
2037       to read one or more bytes before the start of the subject string. Often this
2038       had no effect on PCRE's behaviour, but in some circumstances it could
2039       provoke a segmentation fault.
2041    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
2042       to try to read one or more bytes before the start of the subject string.
2044    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
2045       UTF-8 support could misbehave in various ways if the subject string
2046       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
2047       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
2048       back over UTF-8 characters.)
2051    Version 4.2 14-Apr-03
2052    ---------------------
2054    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
2056    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
2057         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
2058         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
2059         [WIN_PREFIX]: new variable, "cyg" for Cygwin
2060         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
2061           and BUILD_EXEEXT
2062         Note: automatic setting of the BUILD variables is not yet working
2063         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
2064           compile-time but not at link-time
2065         [LINK]: use for linking executables only
2066         make different versions for Windows and non-Windows
2067         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
2068           libraries
2069         [LINK_FOR_BUILD]: new variable
2070         [OBJEXT]: use throughout
2071         [EXEEXT]: use throughout
2072         <winshared>: new target
2073         <wininstall>: new target
2074         <dftables.o>: use native compiler
2075         <dftables>: use native linker
2076         <install>: handle Windows platform correctly
2077         <clean>: ditto
2078         <check>: ditto
2079         copy DLL to top builddir before testing
2081       As part of these changes, -no-undefined was removed again. This was reported
2082       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
2083       in any case.
2085    3. Some tidies to get rid of compiler warnings:
2087       . In the match_data structure, match_limit was an unsigned long int, whereas
2088         match_call_count was an int. I've made them both unsigned long ints.
2090       . In pcretest the fact that a const uschar * doesn't automatically cast to
2091         a void * provoked a warning.
2093       . Turning on some more compiler warnings threw up some "shadow" variables
2094         and a few more missing casts.
2096    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
2097       option, a class that contained a single character with a value between 128
2098       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
2100    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
2101       option, a class that contained several characters, but with at least one
2102       whose value was between 128 and 255 caused PCRE to crash.
2105    Version 4.1 12-Mar-03
2106    ---------------------
2108    1. Compiling with gcc -pedantic found a couple of places where casts were
2109    needed, and a string in dftables.c that was longer than standard compilers are
2110    required to support.
2112    2. Compiling with Sun's compiler found a few more places where the code could
2113    be tidied up in order to avoid warnings.
2115    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
2116    first of these names is deprecated in the latest Autoconf in favour of the name
2117    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
2118    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
2119    analogy I have changed it to CFLAGS_FOR_BUILD.
2121    4. Added -no-undefined to the linking command in the Makefile, because this is
2122    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2123    linking step for the pcreposix library.
2125    5. PCRE was failing to diagnose the case of two named groups with the same
2126    name.
2128    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2129    literal character that is needed in the subject for a match, and scans along to
2130    ensure that it is present before embarking on the full matching process. This
2131    saves time in cases of nested unlimited repeats that are never going to match.
2132    Problem: the scan can take a lot of time if the subject is very long (e.g.
2133    megabytes), thus penalizing straightforward matches. It is now done only if the
2134    amount of subject to be scanned is less than 1000 bytes.
2136    7. A lesser problem with the same optimization is that it was recording the
2137    first character of an anchored pattern as "needed", thus provoking a search
2138    right along the subject, even when the first match of the pattern was going to
2139    fail. The "needed" character is now not set for anchored patterns, unless it
2140    follows something in the pattern that is of non-fixed length. Thus, it still
2141    fulfils its original purpose of finding quick non-matches in cases of nested
2142    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2145    Version 4.0 17-Feb-03
2146    ---------------------
2148    1. If a comment in an extended regex that started immediately after a meta-item
2149    extended to the end of string, PCRE compiled incorrect data. This could lead to
2150    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2152    2. Moved to autoconf 2.53 and libtool 1.4.2.
2154    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2155    the special perltest8 script is no longer needed - all the tests can be run
2156    from a single perltest script.
2158    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2159    by \s. It has now been removed in PCRE. This means it isn't recognized as
2160    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2161    class [:space:] *does* include VT, thereby creating a mess.
2163    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2164    space and tab.
2166    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2167    its new features into the main test script, reducing the number of scripts.
2169    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2170    were backward compatible, and made the (?i) apply to the whole pattern, as if
2171    /i were given. Now it behaves more logically, and applies the option setting
2172    only to what follows. PCRE has been changed to follow suit. However, if it
2173    finds options settings right at the start of the pattern, it extracts them into
2174    the global options, as before. Thus, they show up in the info data.
2176    8. Added support for the \Q...\E escape sequence. Characters in between are
2177    treated as literals. This is slightly different from Perl in that $ and @ are
2178    also handled as literals inside the quotes. In Perl, they will cause variable
2179    interpolation. Note the following examples:
2181        Pattern            PCRE matches      Perl matches
2183        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2184        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2185        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2187    For compatibility with Perl, \Q...\E sequences are recognized inside character
2188    classes as well as outside them.
2190    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2191    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2192    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2193    signed/unsigned warnings.
2195    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2196    option for pcretest, so I've replaced it by a simple function that does just
2197    that job.
2199    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2200    "pcregrep -".
2202    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2203    Java package. This provides some syntactic sugar for simple cases of what my
2204    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2205    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2206    item, you can use this simplified notation. Note that only makes sense with
2207    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2208    greediness, whatever the setting of the PCRE_UNGREEDY option.
2210    13. A change of greediness default within a pattern was not taking effect at
2211    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2212    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2213    was abstracted outside.
2215    14. PCRE now supports the \G assertion. It is true when the current matching
2216    position is at the start point of the match. This differs from \A when the
2217    starting offset is non-zero. Used with the /g option of pcretest (or similar
2218    code), it works in the same way as it does for Perl's /g option. If all
2219    alternatives of a regex begin with \G, the expression is anchored to the start
2220    match position, and the "anchored" flag is set in the compiled expression.
2222    15. Some bugs concerning the handling of certain option changes within patterns
2223    have been fixed. These applied to options other than (?ims). For example,
2224    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2225    been the other way round. Some of this was related to change 7 above.
2227    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2228    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2229    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2230    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2232    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2233    mode. Unlike ".", it always matches newline, whatever the setting of
2234    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2235    assertions. Perl allows it, but it doesn't (in general) work because it can't
2236    calculate the length of the lookbehind. At least, that's the case for Perl
2237    5.8.0 - I've been told they are going to document that it doesn't work in
2238    future.
2240    18. Added an error diagnosis for escapes that PCRE does not support: these are
2241    \L, \l, \N, \P, \p, \U, \u, and \X.
2243    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2244    reading past the end of the pattern in cases such as /[abcd/.
2246    20. PCRE was getting more memory than necessary for patterns with classes that
2247    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2249    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2250    compiling PCRE for use with Virtual Pascal.
2252    22. Small fix to the Makefile to make it work properly if the build is done
2253    outside the source tree.
2255    23. Added a new extension: a condition to go with recursion. If a conditional
2256    subpattern starts with (?(R) the "true" branch is used if recursion has
2257    happened, whereas the "false" branch is used only at the top level.
2259    24. When there was a very long string of literal characters (over 255 bytes
2260    without UTF support, over 250 bytes with UTF support), the computation of how
2261    much memory was required could be incorrect, leading to segfaults or other
2262    strange effects.
2264    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2265    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2266    there was a subsequent back reference to those brackets. This meant that, for
2267    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2268    possible to check for precisely this case. All we can do is abandon the
2269    optimization if .* occurs inside capturing brackets when there are any back
2270    references whatsoever. (See below for a better fix that came later.)
2272    26. The handling of the optimization for finding the first character of a
2273    non-anchored pattern, and for finding a character that is required later in the
2274    match were failing in some cases. This didn't break the matching; it just
2275    failed to optimize when it could. The way this is done has been re-implemented.
2277    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2279    28. Added a new feature that provides some of the functionality that Perl
2280    provides with (?{...}). The facility is termed a "callout". The way it is done
2281    in PCRE is for the caller to provide an optional function, by setting
2282    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2283    global variable. By default it is unset, which disables all calling out. To get
2284    the function called, the regex must include (?C) at appropriate points. This
2285    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2286    This provides a means of identifying different callout points. When PCRE
2287    reaches such a point in the regex, if pcre_callout has been set, the external
2288    function is called. It is provided with data in a structure called
2289    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2290    matching continues; if it returns a non-zero value, the match at the current
2291    point fails. However, backtracking will occur if possible. [This was changed
2292    later and other features added - see item 49 below.]
2294    29. pcretest is upgraded to test the callout functionality. It provides a
2295    callout function that displays information. By default, it shows the start of
2296    the match and the current position in the text. There are some new data escapes
2297    to vary what happens:
2299        \C+         in addition, show current contents of captured substrings
2300        \C-         do not supply a callout function
2301        \C!n        return 1 when callout number n is reached
2302        \C!n!m      return 1 when callout number n is reached for the mth time
2304    30. If pcregrep was called with the -l option and just a single file name, it
2305    output "<stdin>" if a match was found, instead of the file name.
2307    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2308    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2309    pcre_exec(). This saves a malloc/free per call. The default value of
2310    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2311    when configuring.
2313    32. The default maximum size of a compiled pattern is 64K. There have been a
2314    few cases of people hitting this limit. The code now uses macros to handle the
2315    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2316    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2317    configuring. Tests 2 and 5 work only with 2-byte links because they output
2318    debugging information about compiled patterns.
2320    33. Internal code re-arrangements:
2322    (a) Moved the debugging function for printing out a compiled regex into
2323        its own source file (printint.c) and used #include to pull it into
2324        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2325        separate copies.
2327    (b) Defined the list of op-code names for debugging as a macro in
2328        internal.h so that it is next to the definition of the opcodes.
2330    (c) Defined a table of op-code lengths for simpler skipping along compiled
2331        code. This is again a macro in internal.h so that it is next to the
2332        definition of the opcodes.
2334    34. Added support for recursive calls to individual subpatterns, along the
2335    lines of Robin Houston's patch (but implemented somewhat differently).
2337    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2338    allow it to read and process whole directories in Win32. This code was
2339    contributed by Lionel Fourquaux; it has not been tested by me.
2341    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2342    used to name a group. Names consist of alphanumerics and underscores, and must
2343    be unique. Back references use the syntax (?P=name) and recursive calls use
2344    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2345    numbers. The function pcre_fullinfo() can be used after compilation to extract
2346    a name/number map. There are three relevant calls:
2348      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2349      PCRE_INFO_NAMECOUNT            yields the number of entries
2350      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2352    The map is a vector of fixed-size entries. The size of each entry depends on
2353    the length of the longest name used. The first two bytes of each entry are the
2354    group number, most significant byte first. There follows the corresponding
2355    name, zero terminated. The names are in alphabetical order.
2357    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2358    case instead of 255. Making it the same both with and without UTF-8 support
2359    means that the same test output works with both.
2361    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2362    calling malloc() with a zero argument.
2364    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2365    optimization. I've improved things by keeping a bitmap of backreferences with
2366    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2367    fact referenced, the optimization can be applied. It is unlikely that a
2368    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2369    the match to follow \n) will appear inside brackets with a number greater than
2370    31, but if it does, any back reference > 31 suppresses the optimization.
2372    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2373    of disabling numbered capturing parentheses. Any opening parenthesis that is
2374    not followed by ? behaves as if it were followed by ?: but named parentheses
2375    can still be used for capturing (and they will acquire numbers in the usual
2376    way).
2378    41. Redesigned the return codes from the match() function into yes/no/error so
2379    that errors can be passed back from deep inside the nested calls. A malloc
2380    failure while inside a recursive subpattern call now causes the
2381    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2383    42. It is now possible to set a limit on the number of times the match()
2384    function is called in a call to pcre_exec(). This facility makes it possible to
2385    limit the amount of recursion and backtracking, though not in a directly
2386    obvious way, because the match() function is used in a number of different
2387    circumstances. The count starts from zero for each position in the subject
2388    string (for non-anchored patterns). The default limit is, for compatibility, a
2389    large number, namely 10 000 000. You can change this in two ways:
2391    (a) When configuring PCRE before making, you can use --with-match-limit=n
2392        to set a default value for the compiled library.
2394    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2395        a different value is set. See 45 below.
2397    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2399    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2400    of things that can be changed at compile time. The first argument specifies
2401    what is wanted and the second points to where the information is to be placed.
2402    The current list of available information is:
2404      PCRE_CONFIG_UTF8
2406    The output is an integer that is set to one if UTF-8 support is available;
2407    otherwise it is set to zero.
2411    The output is an integer that it set to the value of the code that is used for
2412    newline. It is either LF (10) or CR (13).
2416    The output is an integer that contains the number of bytes used for internal
2417    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2421    The output is an integer that contains the threshold above which the POSIX
2422    interface uses malloc() for output vectors. See item 31 above.
2426    The output is an unsigned integer that contains the default limit of the number
2427    of match() calls in a pcre_exec() execution. See 42 above.
2429    44. pcretest has been upgraded by the addition of the -C option. This causes it
2430    to extract all the available output from the new pcre_config() function, and to
2431    output it. The program then exits immediately.
2433    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2434    order to support additional features. One way would have been to define
2435    pcre_exec2() (for example) with extra arguments, but this would not have been
2436    extensible, and would also have required all calls to the original function to
2437    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2438    is used for passing in "extra" data from pcre_study().
2440    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2441    contains the following fields:
2443      flags         a bitmap indicating which of the following fields are set
2444      study_data    opaque data from pcre_study()
2445      match_limit   a way of specifying a limit on match() calls for a specific
2446                      call to pcre_exec()
2447      callout_data  data for callouts (see 49 below)
2449    The flag bits are also defined in pcre.h, and are
2455    The pcre_study() function now returns one of these new pcre_extra blocks, with
2456    the actual study data pointed to by the study_data field, and the
2457    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2458    before. That is, this change is entirely upwards-compatible and requires no
2459    change to existing code.
2461    If you want to pass in additional data to pcre_exec(), you can either place it
2462    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2463    block.
2465    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2466    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2467    times with different match limits, until it finds the minimum value needed for
2468    pcre_exec() to complete. The value is then output. This can be instructive; for
2469    most simple matches the number is quite small, but for pathological cases it
2470    gets very large very quickly.
2472    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2473    returns the size of the data block pointed to by the study_data field in a
2474    pcre_extra block, that is, the value that was passed as the argument to
2475    pcre_malloc() when PCRE was getting memory in which to place the information
2476    created by pcre_study(). The fourth argument should point to a size_t variable.
2477    pcretest has been extended so that this information is shown after a successful
2478    pcre_study() call when information about the compiled regex is being displayed.
2480    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2481    because what follows is always an absolute path. (Later: it turns out that this
2482    is more than cosmetic for MinGW, because it doesn't like empty path
2483    components.)
2485    49. Some changes have been made to the callout feature (see 28 above):
2487    (i)  A callout function now has three choices for what it returns:
2489           0  =>  success, carry on matching
2490         > 0  =>  failure at this point, but backtrack if possible
2491         < 0  =>  serious error, return this value from pcre_exec()
2493         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2494         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2495         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2496         use by callout functions. It will never be used by PCRE itself.
2498    (ii) The pcre_extra structure (see 45 above) has a void * field called
2499         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2500         pcre_callout_block structure has a field of the same name. The contents of
2501         the field passed in the pcre_extra structure are passed to the callout
2502         function in the corresponding field in the callout block. This makes it
2503         easier to use the same callout-containing regex from multiple threads. For
2504         testing, the pcretest program has a new data escape
2506           \C*n        pass the number n (may be negative) as callout_data
2508         If the callout function in pcretest receives a non-zero value as
2509         callout_data, it returns that value.
2511    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2512    there were some redundant $(CFLAGS) in commands that are now specified as
2513    $(LINK), which already includes $(CFLAGS).
2515    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2516    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2517    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2518    one-byte characters throughout. Note that case-insensitive matching applies
2519    only to characters whose values are less than 256. PCRE doesn't support the
2520    notion of cases for higher-valued characters.
2522    (i)   A character class whose characters are all within 0-255 is handled as
2523          a bit map, and the map is inverted for negative classes. Previously, a
2524          character > 255 always failed to match such a class; however it should
2525          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2527    (ii)  A negated character class with a single character < 255 is coded as
2528          "not this character" (OP_NOT). This wasn't working properly when the test
2529          character was multibyte, either singly or repeated.
2531    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2532          mode, for example: \x{100}{2,3}.
2534    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2535          singly or repeated) now correctly test multibyte characters. However,
2536          PCRE doesn't recognize any characters with values greater than 255 as
2537          digits, spaces, or word characters. Such characters always match \D, \S,
2538          and \W, and never match \d, \s, or \w.
2540    (v)   Classes may now contain characters and character ranges with values
2541          greater than 255. For example: [ab\x{100}-\x{400}].
2543    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2544          PCRE in UTF-8 mode.
2546    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2547    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2548    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2549    value.)
2551    53. The single man page has become too large. I have therefore split it up into
2552    a number of separate man pages. These also give rise to individual HTML pages;
2553    these are now put in a separate directory, and there is an index.html page that
2554    lists them all. Some hyperlinking between the pages has been installed.
2556    54. Added convenience functions for handling named capturing parentheses.
2558    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2559    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2560    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2561    are faulted.
2563    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2564    calling configure. These values are used when compiling the dftables.c program
2565    which is run to generate the source of the default character tables. They
2566    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2567    you will need to set these values.
2569    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2572    Version 3.9 02-Jan-02
2573    ---------------------
2575    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2577    2. If --disable-static was given, the building process failed when trying to
2578    build pcretest and pcregrep. (For some reason it was using libtool to compile
2579    them, which is not right, as they aren't part of the library.)
2582    Version 3.8 18-Dec-01
2583    ---------------------
2585    1. The experimental UTF-8 code was completely screwed up. It was packing the
2586    bytes in the wrong order. How dumb can you get?
2589    Version 3.7 29-Oct-01
2590    ---------------------
2592    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2593    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2594    this didn't happen under Solaris 8, where I normally test things.
2596    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2597    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2598    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2599    this fix an hour or so after the initial 3.7 release.)
2602    Version 3.6 23-Oct-01
2603    ---------------------
2605    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2606    offsets passed as NULL with zero offset count.
2608    2. The config.guess and config.sub files had not been updated when I moved to
2609    the latest autoconf.
2612    Version 3.5 15-Aug-01
2613    ---------------------
2615    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2616    had been forgotten.
2618    2. By using declared but undefined structures, we can avoid using "void"
2619    definitions in pcre.h while keeping the internal definitions of the structures
2620    private.
2622    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2623    user point of view, this means that both static and shared libraries are built
2624    by default, but this can be individually controlled. More of the work of
2625    handling this static/shared cases is now inside libtool instead of PCRE's make
2626    file.
2628    4. The pcretest utility is now installed along with pcregrep because it is
2629    useful for users (to test regexs) and by doing this, it automatically gets
2630    relinked by libtool. The documentation has been turned into a man page, so
2631    there are now .1, .txt, and .html versions in /doc.
2633    5. Upgrades to pcregrep:
2634       (i)   Added long-form option names like gnu grep.
2635       (ii)  Added --help to list all options with an explanatory phrase.
2636       (iii) Added -r, --recursive to recurse into sub-directories.
2637       (iv)  Added -f, --file to read patterns from a file.
2639    6. pcre_exec() was referring to its "code" argument before testing that
2640    argument for NULL (and giving an error if it was NULL).
2642    7. Upgraded Makefile.in to allow for compiling in a different directory from
2643    the source directory.
2645    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2646    options bits, the pointer it was passed was to an int instead of to an unsigned
2647    long int. This mattered only on 64-bit systems.
2649    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2650    generated) instead of pcre.in, which it its source. Also made the same change
2651    in several of the .c files.
2653    10. A new release of gcc defines printf() as a macro, which broke pcretest
2654    because it had an ifdef in the middle of a string argument for printf(). Fixed
2655    by using separate calls to printf().
2657    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2658    script, to force use of CR or LF instead of \n in the source. On non-Unix
2659    systems, the value can be set in config.h.
2661    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2662    absolute limit. Changed the text of the error message to make this clear, and
2663    likewise updated the man page.
2665    13. The limit of 99 on the number of capturing subpatterns has been removed.
2666    The new limit is 65535, which I hope will not be a "real" limit.
2669  Version 3.4 22-Aug-00  Version 3.4 22-Aug-00
2670  ---------------------  ---------------------

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