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revision 87 by nigel, Sat Feb 24 21:41:21 2007 UTC revision 276 by ph10, Wed Nov 21 15:39:20 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.5 12-Nov-07
5    ---------------------
7    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
8        values in parens when parsing an RE using the C++ wrapper."
10    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
11        Characters greater than 255 were excluded from the class instead of being
12        included.
14    3.  The same bug as (2) above applied to negated POSIX classes such as
15        [:^space:].
17    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
18        defined or documented. It seems to have been a typo for PCRE_STATIC, so
19        I have changed it.
21    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
22        first named subpattern) and a construct such as (?&a) would reference the
23        first named subpattern whose name started with "a" (in other words, the
24        length check was missing). Both these problems are fixed. "Subpattern name
25        expected" is now given for (?&) (a zero-length name), and this patch also
26        makes it give the same error for \k'' (previously it complained that that
27        was a reference to a non-existent subpattern).
29    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
30        this is right because (?- can be followed by option settings as well as by
31        digits. I have, however, made the messages clearer.
33    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
34        than the number used in the conditional) now cause a compile-time error.
35        This is actually not compatible with Perl, which accepts such patterns, but
36        treats the conditional as always being FALSE (as PCRE used to), but it
37        seems to me that giving a diagnostic is better.
39    8.  Change "alphameric" to the more common word "alphanumeric" in comments
40        and messages.
42    9.  Fix two occurrences of "backslash" in comments that should have been
43        "backspace".
45    10. Remove two redundant lines of code that can never be obeyed (their function
46        was moved elsewhere).
49    Version 7.4 21-Sep-07
50    ---------------------
52    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
53        means that a class such as [\s] counted as "explicit reference to CR or
54        LF". That isn't really right - the whole point of the change was to try to
55        help when there was an actual mention of one of the two characters. So now
56        the change happens only if \r or \n (or a literal CR or LF) character is
57        encountered.
59    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
60        of both had grown to the point where there were only 3 bits left.
61        Fortunately, there was spare space in the data structure, and so I have
62        moved the internal flags into a new 16-bit field to free up more option
63        bits.
65    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
66        but did not set the internal JCHANGED flag - either of these is enough to
67        control the way the "get" function works - but the PCRE_INFO_JCHANGED
68        facility is supposed to tell if (?J) was ever used, so now (?J) at the
69        start sets both bits.
71    4.  Added options (at build time, compile time, exec time) to change \R from
72        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
74    5.  doc/pcresyntax.html was missing from the distribution.
76    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
77        compatibility, even though it is no longer used.
79    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
80        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
81        windows.h file is present (where different names are used). [This was
82        reversed later after testing - see 16 below.]
84    8.  Changed all #include <config.h> to #include "config.h". There were also
85        some further <pcre.h> cases that I changed to "pcre.h".
87    9.  When pcregrep was used with the --colour option, it missed the line ending
88        sequence off the lines that it output.
90    10. It was pointed out to me that arrays of string pointers cause lots of
91        relocations when a shared library is dynamically loaded. A technique of
92        using a single long string with a table of offsets can drastically reduce
93        these. I have refactored PCRE in four places to do this. The result is
94        dramatic:
96          Originally:                          290
97          After changing UCP table:            187
98          After changing error message table:   43
99          After changing table of "verbs"       36
100          After changing table of Posix names   22
102        Thanks to the folks working on Gregex for glib for this insight.
104    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
105        unicode-properties was also set.
107    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
109    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
110        checked only for CRLF.
112    14. Added casts to pcretest.c to avoid compiler warnings.
114    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
116    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
117        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
118        entirely. This removes changes made in 7 above.
120    17. The CMake files have been updated, and there is now more information about
121        building with CMake in the NON-UNIX-USE document.
124    Version 7.3 28-Aug-07
125    ---------------------
127     1. In the rejigging of the build system that eventually resulted in 7.1, the
128        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
129        brackets there is not right, since it causes compilers to look for an
130        installed pcre.h, not the version that is in the source that is being
131        compiled (which of course may be different). I have changed it back to:
133          #include "pcre.h"
135        I have a vague recollection that the change was concerned with compiling in
136        different directories, but in the new build system, that is taken care of
137        by the VPATH setting the Makefile.
139     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
140        when the subject happened to end in the byte 0x85 (e.g. if the last
141        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
142        characters but of course it shouldn't be taken as a newline when it is part
143        of another character. The bug was that, for an unlimited repeat of . in
144        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
145        characters when looking for a newline.
147     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
149     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
150        in debug output.
152     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
153        long printing in the pcrecpp unittest when running under MinGW.
155     6. ESC_K was left out of the EBCDIC table.
157     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
158        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
159        limit also applies to "virtual nesting" when a pattern is recursive, and in
160        this case 1000 isn't so big. I have been able to remove this limit at the
161        expense of backing off one optimization in certain circumstances. Normally,
162        when pcre_exec() would call its internal match() function recursively and
163        immediately return the result unconditionally, it uses a "tail recursion"
164        feature to save stack. However, when a subpattern that can match an empty
165        string has an unlimited repetition quantifier, it no longer makes this
166        optimization. That gives it a stack frame in which to save the data for
167        checking that an empty string has been matched. Previously this was taken
168        from the 1000-entry workspace that had been reserved. So now there is no
169        explicit limit, but more stack is used.
171     8. Applied Daniel's patches to solve problems with the import/export magic
172        syntax that is required for Windows, and which was going wrong for the
173        pcreposix and pcrecpp parts of the library. These were overlooked when this
174        problem was solved for the main library.
176     9. There were some crude static tests to avoid integer overflow when computing
177        the size of patterns that contain repeated groups with explicit upper
178        limits. As the maximum quantifier is 65535, the maximum group length was
179        set at 30,000 so that the product of these two numbers did not overflow a
180        32-bit integer. However, it turns out that people want to use groups that
181        are longer than 30,000 bytes (though not repeat them that many times).
182        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
183        made it possible to implement the integer overflow checks in a much more
184        dynamic way, which I have now done. The artificial limitation on group
185        length has been removed - we now have only the limit on the total length of
186        the compiled pattern, which depends on the LINK_SIZE setting.
188    10. Fixed a bug in the documentation for get/copy named substring when
189        duplicate names are permitted. If none of the named substrings are set, the
190        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
191        empty string.
193    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
194        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
195        because the ] is interpreted as the first data character and the
196        terminating ] is not found. PCRE has been made compatible with Perl in this
197        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
198        cause memory overwriting.
200    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
201        string has been matched (to stop an infinite loop). It was not recognizing
202        a conditional subpattern that could match an empty string if that
203        subpattern was within another subpattern. For example, it looped when
204        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
205        condition was not nested. This bug has been fixed.
207    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
208        past the start of the subject in the presence of bytes with the top bit
209        set, for example "\x8aBCD".
211    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
212        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
214    14. Optimized (?!) to (*FAIL).
216    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
217        This restricts code points to be within the range 0 to 0x10FFFF, excluding
218        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
219        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
220        does: it's just the validity check that is more restrictive.
222    16. Inserted checks for integer overflows during escape sequence (backslash)
223        processing, and also fixed erroneous offset values for syntax errors during
224        backslash processing.
226    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
227        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
229    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
230        caused an overrun.
232    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
233        something other than just ASCII characters) inside a group that had an
234        unlimited repeat caused a loop at compile time (while checking to see
235        whether the group could match an empty string).
237    20. Debugging a pattern containing \p or \P could cause a crash. For example,
238        [\P{Any}] did so. (Error in the code for printing property names.)
240    21. An orphan \E inside a character class could cause a crash.
242    22. A repeated capturing bracket such as (A)? could cause a wild memory
243        reference during compilation.
245    23. There are several functions in pcre_compile() that scan along a compiled
246        expression for various reasons (e.g. to see if it's fixed length for look
247        behind). There were bugs in these functions when a repeated \p or \P was
248        present in the pattern. These operators have additional parameters compared
249        with \d, etc, and these were not being taken into account when moving along
250        the compiled data. Specifically:
252        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
253            length.
255        (b) An item such as \pL+ within a repeated group could cause crashes or
256            loops.
258        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
259            "reference to non-existent subpattern" error.
261        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
263    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
264        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
266    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
268    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
269        character were causing crashes (broken optimization).
271    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
272        \p or \P) caused a compile-time loop.
274    28. More problems have arisen in unanchored patterns when CRLF is a valid line
275        break. For example, the unstudied pattern [\r\n]A does not match the string
276        "\r\nA" because change 7.0/46 below moves the current point on by two
277        characters after failing to match at the start. However, the pattern \nA
278        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
279        the same is true. There doesn't seem any very clean way out of this, but
280        what I have chosen to do makes the common cases work: PCRE now takes note
281        of whether there can be an explicit match for \r or \n anywhere in the
282        pattern, and if so, 7.0/46 no longer applies. As part of this change,
283        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
284        pattern has explicit CR or LF references.
286    29. Added (*CR) etc for changing newline setting at start of pattern.
289    Version 7.2 19-Jun-07
290    ---------------------
292     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
293        which is apparently normally available under Windows.
295     2. Re-jig the pcregrep tests with different newline settings in an attempt
296        to make them independent of the local environment's newline setting.
298     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
300     4. Some of the "internals" tests were previously cut out when the link size
301        was not 2, because the output contained actual offsets. The recent new
302        "Z" feature of pcretest means that these can be cut out, making the tests
303        usable with all link sizes.
305     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
306        stack recursion. This gives a massive performance boost under BSD, but just
307        a small improvement under Linux. However, it saves one field in the frame
308        in all cases.
310     6. Added more features from the forthcoming Perl 5.10:
312        (a) (?-n) (where n is a string of digits) is a relative subroutine or
313            recursion call. It refers to the nth most recently opened parentheses.
315        (b) (?+n) is also a relative subroutine call; it refers to the nth next
316            to be opened parentheses.
318        (c) Conditions that refer to capturing parentheses can be specified
319            relatively, for example, (?(-2)... or (?(+3)...
321        (d) \K resets the start of the current match so that everything before
322            is not part of it.
324        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
326        (f) \g{name} is another synonym - part of Perl 5.10's unification of
327            reference syntax.
329        (g) (?| introduces a group in which the numbering of parentheses in each
330            alternative starts with the same number.
332        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
334     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
337     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
338        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
339        for detecting groups that can match an empty string.
341     9. A pattern with a very large number of alternatives (more than several
342        hundred) was running out of internal workspace during the pre-compile
343        phase, where pcre_compile() figures out how much memory will be needed. A
344        bit of new cunning has reduced the workspace needed for groups with
345        alternatives. The 1000-alternative test pattern now uses 12 bytes of
346        workspace instead of running out of the 4096 that are available.
348    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
350    11. Applied patch from Google to remove an optimization that didn't quite work.
351        The report of the bug said:
353          pcrecpp::RE("a*").FullMatch("aaa") matches, while
354          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
355          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
357    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
358        it matched the wrong number of bytes.
361    Version 7.1 24-Apr-07
362    ---------------------
364     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
365        that is more "standard", making use of automake and other Autotools. There
366        is some re-arrangement of the files and adjustment of comments consequent
367        on this.
369     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
370        for recursive directory scanning broke on some systems because the files
371        are not scanned in any specific order and on different systems the order
372        was different. A call to "sort" has been inserted into RunGrepTest for the
373        approprate test as a short-term fix. In the longer term there may be an
374        alternative.
376     3. I had an email from Eric Raymond about problems translating some of PCRE's
377        man pages to HTML (despite the fact that I distribute HTML pages, some
378        people do their own conversions for various reasons). The problems
379        concerned the use of low-level troff macros .br and .in. I have therefore
380        removed all such uses from the man pages (some were redundant, some could
381        be replaced by .nf/.fi pairs). The 132html script that I use to generate
382        HTML has been updated to handle .nf/.fi and to complain if it encounters
383        .br or .in.
385     4. Updated comments in configure.ac that get placed in config.h.in and also
386        arranged for config.h to be included in the distribution, with the name
387        config.h.generic, for the benefit of those who have to compile without
388        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
390     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
391        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
392        makevp.bat for the current PCRE, using the additional files
393        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
395     6. A Windows user reported a minor discrepancy with test 2, which turned out
396        to be caused by a trailing space on an input line that had got lost in his
397        copy. The trailing space was an accident, so I've just removed it.
399     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
400        that is needed.
402     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
403        as "const" (a) because they are and (b) because it helps the PHP
404        maintainers who have recently made a script to detect big data structures
405        in the php code that should be moved to the .rodata section. I remembered
406        to update Builducptable as well, so it won't revert if ucptable.h is ever
407        re-created.
409     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
410        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
411        order to be able to cut out the UTF-8 tables in the latter when UTF-8
412        support is not required. This saves 1.5-2K of code, which is important in
413        some applications.
415        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
416        so as not to refer to the tables, even though these functions will never be
417        called when UTF-8 support is disabled. Otherwise there are problems with a
418        shared library.
420    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
422        (a) It was defining its arguments as char * instead of void *.
424        (b) It was assuming that all moves were upwards in memory; this was true
425            a long time ago when I wrote it, but is no longer the case.
427        The emulated memove() is provided for those environments that have neither
428        memmove() nor bcopy(). I didn't think anyone used it these days, but that
429        is clearly not the case, as these two bugs were recently reported.
431    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
432        and Detrail to create the HTML documentation, the .txt form of the man
433        pages, and it removes trailing spaces from listed files. It also creates
434        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
435        case, it wraps all the #defines with #ifndefs. This script should be run
436        before "make dist".
438    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
439        with Unicode property support.
441        (a) For a maximizing quantifier, if the two different cases of the
442            character were of different lengths in their UTF-8 codings (there are
443            some cases like this - I found 11), and the matching function had to
444            back up over a mixture of the two cases, it incorrectly assumed they
445            were both the same length.
447        (b) When PCRE was configured to use the heap rather than the stack for
448            recursion during matching, it was not correctly preserving the data for
449            the other case of a UTF-8 character when checking ahead for a match
450            while processing a minimizing repeat. If the check also involved
451            matching a wide character, but failed, corruption could cause an
452            erroneous result when trying to check for a repeat of the original
453            character.
455    13. Some tidying changes to the testing mechanism:
457        (a) The RunTest script now detects the internal link size and whether there
458            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
459            values substituted by "configure". (The RunGrepTest script already did
460            this for UTF-8.) The configure.ac script no longer substitutes the
461            relevant variables.
463        (b) The debugging options /B and /D in pcretest show the compiled bytecode
464            with length and offset values. This means that the output is different
465            for different internal link sizes. Test 2 is skipped for link sizes
466            other than 2 because of this, bypassing the problem. Unfortunately,
467            there was also a test in test 3 (the locale tests) that used /B and
468            failed for link sizes other than 2. Rather than cut the whole test out,
469            I have added a new /Z option to pcretest that replaces the length and
470            offset values with spaces. This is now used to make test 3 independent
471            of link size. (Test 2 will be tidied up later.)
473    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
474        segmentation fault instead of returning the appropriate error message.
476    15. In multiline mode when the newline sequence was set to "any", the pattern
477        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
478        This doesn't seem right; it now treats the CRLF combination as the line
479        ending, and so does not match in that case. It's only a pattern such as ^$
480        that would hit this one: something like ^ABC$ would have failed after \r
481        and then tried again after \r\n.
483    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
484        in an attempt to make files that differ only in their line terminators
485        compare equal. This works on Linux.
487    17. Under certain error circumstances pcregrep might try to free random memory
488        as it exited. This is now fixed, thanks to valgrind.
490    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
491        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
492        was because its rules for how to advance for /g after matching an empty
493        string at the end of a line did not allow for this case. They now check for
494        it specially.
496    20. pcretest is supposed to handle patterns and data of any length, by
497        extending its buffers when necessary. It was getting this wrong when the
498        buffer for a data line had to be extended.
500    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
501        CRLF as a newline sequence.
503    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
504        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
505        I have nevertheless tidied it up.
507    23. Added some casts to kill warnings from HP-UX ia64 compiler.
509    24. Added a man page for pcre-config.
512    Version 7.0 19-Dec-06
513    ---------------------
515     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
516        moving to gcc 4.1.1.
518     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
519        sys/time.h, which is documented as needed for this function. It doesn't
520        seem to matter on Linux, but it showed up on some releases of OS X.
522     3. It seems that there are systems where bytes whose values are greater than
523        127 match isprint() in the "C" locale. The "C" locale should be the
524        default when a C program starts up. In most systems, only ASCII printing
525        characters match isprint(). This difference caused the output from pcretest
526        to vary, making some of the tests fail. I have changed pcretest so that:
528        (a) When it is outputting text in the compiled version of a pattern, bytes
529            other than 32-126 are always shown as hex escapes.
531        (b) When it is outputting text that is a matched part of a subject string,
532            it does the same, unless a different locale has been set for the match
533            (using the /L modifier). In this case, it uses isprint() to decide.
535     4. Fixed a major bug that caused incorrect computation of the amount of memory
536        required for a compiled pattern when options that changed within the
537        pattern affected the logic of the preliminary scan that determines the
538        length. The relevant options are -x, and -i in UTF-8 mode. The result was
539        that the computed length was too small. The symptoms of this bug were
540        either the PCRE error "internal error: code overflow" from pcre_compile(),
541        or a glibc crash with a message such as "pcretest: free(): invalid next
542        size (fast)". Examples of patterns that provoked this bug (shown in
543        pcretest format) are:
545          /(?-x: )/x
546          /(?x)(?-x: \s*#\s*)/
547          /((?i)[\x{c0}])/8
548          /(?i:[\x{c0}])/8
550        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
551        is now done differently.
553     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
554        wrapper classes; (b) implement a new function in the C++ scanner that is
555        more efficient than the old way of doing things because it avoids levels of
556        recursion in the regex matching; (c) add a paragraph to the documentation
557        for the FullMatch() function.
559     6. The escape sequence \n was being treated as whatever was defined as
560        "newline". Not only was this contrary to the documentation, which states
561        that \n is character 10 (hex 0A), but it also went horribly wrong when
562        "newline" was defined as CRLF. This has been fixed.
564     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
565        was being set to -1 for the "end of line" case (supposedly a value that no
566        character can have). Though this value is never used (the check for end of
567        line is "zero bytes in current character"), it caused compiler complaints.
568        I've changed it to 0xffffffff.
570     8. In pcre_version.c, the version string was being built by a sequence of
571        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
572        string (as it is for production releases) called a macro with an empty
573        argument. The C standard says the result of this is undefined. The gcc
574        compiler treats it as an empty string (which was what was wanted) but it is
575        reported that Visual C gives an error. The source has been hacked around to
576        avoid this problem.
578     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
579        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
580        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
581        of them did).
583    10. Originally, pcretest opened its input and output without "b"; then I was
584        told that "b" was needed in some environments, so it was added for release
585        5.0 to both the input and output. (It makes no difference on Unix-like
586        systems.) Later I was told that it is wrong for the input on Windows. I've
587        now abstracted the modes into two macros, to make it easier to fiddle with
588        them, and removed "b" from the input mode under Windows.
590    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
592    12. Added -help and --help to pcretest as an official way of being reminded
593        of the options.
595    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
596        and pcrecpp.cc because they annoy compilers at high warning levels.
598    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
600    15. Fixed an occurrence of == in configure.ac that should have been = (shell
601        scripts are not C programs :-) and which was not noticed because it works
602        on Linux.
604    16. pcretest is supposed to handle any length of pattern and data line (as one
605        line or as a continued sequence of lines) by extending its input buffer if
606        necessary. This feature was broken for very long pattern lines, leading to
607        a string of junk being passed to pcre_compile() if the pattern was longer
608        than about 50K.
610    17. I have done a major re-factoring of the way pcre_compile() computes the
611        amount of memory needed for a compiled pattern. Previously, there was code
612        that made a preliminary scan of the pattern in order to do this. That was
613        OK when PCRE was new, but as the facilities have expanded, it has become
614        harder and harder to keep it in step with the real compile phase, and there
615        have been a number of bugs (see for example, 4 above). I have now found a
616        cunning way of running the real compile function in a "fake" mode that
617        enables it to compute how much memory it would need, while actually only
618        ever using a few hundred bytes of working memory and without too many
619        tests of the mode. This should make future maintenance and development
620        easier. A side effect of this work is that the limit of 200 on the nesting
621        depth of parentheses has been removed (though this was never a serious
622        limitation, I suspect). However, there is a downside: pcre_compile() now
623        runs more slowly than before (30% or more, depending on the pattern). I
624        hope this isn't a big issue. There is no effect on runtime performance.
626    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
627        newline (only possible for the last line of a file) and it was a
628        pattern that set a locale (followed by /Lsomething), pcretest crashed.
630    19. Added additional timing features to pcretest. (1) The -tm option now times
631        matching only, not compiling. (2) Both -t and -tm can be followed, as a
632        separate command line item, by a number that specifies the number of
633        repeats to use when timing. The default is 50000; this gives better
634        precision, but takes uncomfortably long for very large patterns.
636    20. Extended pcre_study() to be more clever in cases where a branch of a
637        subpattern has no definite first character. For example, (a*|b*)[cd] would
638        previously give no result from pcre_study(). Now it recognizes that the
639        first character must be a, b, c, or d.
641    21. There was an incorrect error "recursive call could loop indefinitely" if
642        a subpattern (or the entire pattern) that was being tested for matching an
643        empty string contained only one non-empty item after a nested subpattern.
644        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
645        incorrectly, because the \d was being skipped in the check.
647    22. The pcretest program now has a new pattern option /B and a command line
648        option -b, which is equivalent to adding /B to every pattern. This causes
649        it to show the compiled bytecode, without the additional information that
650        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
651        is the same as /B/I).
653    23. A new optimization is now able automatically to treat some sequences such
654        as a*b as a*+b. More specifically, if something simple (such as a character
655        or a simple class like \d) has an unlimited quantifier, and is followed by
656        something that cannot possibly match the quantified thing, the quantifier
657        is automatically "possessified".
659    24. A recursive reference to a subpattern whose number was greater than 39
660        went wrong under certain circumstances in UTF-8 mode. This bug could also
661        have affected the operation of pcre_study().
663    25. Realized that a little bit of performance could be had by replacing
664        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
666    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
668    27. Possessive quantifiers such as a++ were previously implemented by turning
669        them into atomic groups such as ($>a+). Now they have their own opcodes,
670        which improves performance. This includes the automatically created ones
671        from 23 above.
673    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
674        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
675        the first matched character to be a colon. This applied both to named and
676        numbered groups.
678    29. The ucpinternal.h header file was missing its idempotency #ifdef.
680    30. I was sent a "project" file called libpcre.a.dev which I understand makes
681        building PCRE on Windows easier, so I have included it in the distribution.
683    31. There is now a check in pcretest against a ridiculously large number being
684        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
685        loop, the loop is abandoned.
687    32. Forward references to subpatterns in conditions such as (?(2)...) where
688        subpattern 2 is defined later cause pcre_compile() to search forwards in
689        the pattern for the relevant set of parentheses. This search went wrong
690        when there were unescaped parentheses in a character class, parentheses
691        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
693    33. "Subroutine" calls and backreferences were previously restricted to
694        referencing subpatterns earlier in the regex. This restriction has now
695        been removed.
697    34. Added a number of extra features that are going to be in Perl 5.10. On the
698        whole, these are just syntactic alternatives for features that PCRE had
699        previously implemented using the Python syntax or my own invention. The
700        other formats are all retained for compatibility.
702        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
703            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
704            also .NET compatible.
706        (b) A recursion or subroutine call to a named group can now be defined as
707            (?&name) as well as (?P>name).
709        (c) A backreference to a named group can now be defined as \k<name> or
710            \k'name' as well as (?P=name). The new forms, as well as being in Perl
711            5.10, are also .NET compatible.
713        (d) A conditional reference to a named group can now use the syntax
714            (?(<name>) or (?('name') as well as (?(name).
716        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
717            groups (named and numbered) that are never evaluated inline, but can be
718            called as "subroutines" from elsewhere. In effect, the DEFINE condition
719            is always false. There may be only one alternative in such a group.
721        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
722            as the simple (?(R). The condition is true only if the most recent
723            recursion is that of the given number or name. It does not search out
724            through the entire recursion stack.
726        (g) The escape \gN or \g{N} has been added, where N is a positive or
727            negative number, specifying an absolute or relative reference.
729    35. Tidied to get rid of some further signed/unsigned compiler warnings and
730        some "unreachable code" warnings.
732    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
733        things, this adds five new scripts.
735    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
736        There were also incompatibilities regarding the handling of \Q..\E inside
737        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
738        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
740    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
741        matches an empty string, and forcibly breaks the loop. There were bugs in
742        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
743        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
744        separate and independent bugs (that affected different cases) have been
745        fixed.
747    39. Refactored the code to abolish the use of different opcodes for small
748        capturing bracket numbers. This is a tidy that I avoided doing when I
749        removed the limit on the number of capturing brackets for 3.5 back in 2001.
750        The new approach is not only tidier, it makes it possible to reduce the
751        memory needed to fix the previous bug (38).
753    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
754        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
755        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
756        mode.
758    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
759        report.
761    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
762        copy construction and assignment in the C++ wrapper.
764    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
765        couple of bugs that could have given wrong results in the "--newline=crlf"
766        case.
768    44. Added a number of casts and did some reorganization of signed/unsigned int
769        variables following suggestions from Dair Grant. Also renamed the variable
770        "this" as "item" because it is a C++ keyword.
772    45. Arranged for dftables to add
774          #include "pcre_internal.h"
776        to pcre_chartables.c because without it, gcc 4.x may remove the array
777        definition from the final binary if PCRE is built into a static library and
778        dead code stripping is activated.
780    46. For an unanchored pattern, if a match attempt fails at the start of a
781        newline sequence, and the newline setting is CRLF or ANY, and the next two
782        characters are CRLF, advance by two characters instead of one.
785    Version 6.7 04-Jul-06
786    ---------------------
788     1. In order to handle tests when input lines are enormously long, pcretest has
789        been re-factored so that it automatically extends its buffers when
790        necessary. The code is crude, but this _is_ just a test program. The
791        default size has been increased from 32K to 50K.
793     2. The code in pcre_study() was using the value of the re argument before
794        testing it for NULL. (Of course, in any sensible call of the function, it
795        won't be NULL.)
797     3. The memmove() emulation function in pcre_internal.h, which is used on
798        systems that lack both memmove() and bcopy() - that is, hardly ever -
799        was missing a "static" storage class specifier.
801     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
802        containing an extended class (one that cannot be represented by a bitmap
803        because it contains high-valued characters or Unicode property items, e.g.
804        [\pZ]). Almost always one would set UTF-8 mode when processing such a
805        pattern, but PCRE should not loop if you do not (it no longer does).
806        [Detail: two cases were found: (a) a repeated subpattern containing an
807        extended class; (b) a recursive reference to a subpattern that followed a
808        previous extended class. It wasn't skipping over the extended class
809        correctly when UTF-8 mode was not set.]
811     5. A negated single-character class was not being recognized as fixed-length
812        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
813        compile error "lookbehind assertion is not fixed length".
815     6. The RunPerlTest auxiliary script was showing an unexpected difference
816        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
817        write a Perl script that can interpret lines of an input file either as
818        byte characters or as UTF-8, which is what "perltest" was being required to
819        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
820        can't do is switch easily at run time between having the "use utf8;" pragma
821        or not. In the end, I fudged it by using the RunPerlTest script to insert
822        "use utf8;" explicitly for the UTF-8 tests.
824     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
825        the end of the subject string, contrary to the documentation and to what
826        Perl does. This was true of both matching functions. Now it matches only at
827        the start of the subject and immediately after *internal* newlines.
829     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
830        a pointer to an int instead of a pointer to an unsigned long int. This
831        caused problems on 64-bit systems.
833     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
834        instance of the 'standard' template library not being so standard".
836    10. There was no check on the number of named subpatterns nor the maximum
837        length of a subpattern name. The product of these values is used to compute
838        the size of the memory block for a compiled pattern. By supplying a very
839        long subpattern name and a large number of named subpatterns, the size
840        computation could be caused to overflow. This is now prevented by limiting
841        the length of names to 32 characters, and the number of named subpatterns
842        to 10,000.
844    11. Subpatterns that are repeated with specific counts have to be replicated in
845        the compiled pattern. The size of memory for this was computed from the
846        length of the subpattern and the repeat count. The latter is limited to
847        65535, but there was no limit on the former, meaning that integer overflow
848        could in principle occur. The compiled length of a repeated subpattern is
849        now limited to 30,000 bytes in order to prevent this.
851    12. Added the optional facility to have named substrings with the same name.
853    13. Added the ability to use a named substring as a condition, using the
854        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
855        are numbers (not recommended). Forward references are permitted.
857    14. Added forward references in named backreferences (if you see what I mean).
859    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
860        pattern could run off the end of the subject. For example, the pattern
861        "(?s)(.{1,5})"8 did this with the subject "ab".
863    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
864        PCRE_CASELESS was set when matching characters that were quantified with ?
865        or *.
867    17. A character class other than a single negated character that had a minimum
868        but no maximum quantifier - for example [ab]{6,} - was not handled
869        correctly by pce_dfa_exec(). It would match only one character.
871    18. A valid (though odd) pattern that looked like a POSIX character
872        class but used an invalid character after [ (for example [[,abc,]]) caused
873        pcre_compile() to give the error "Failed: internal error: code overflow" or
874        in some cases to crash with a glibc free() error. This could even happen if
875        the pattern terminated after [[ but there just happened to be a sequence of
876        letters, a binary zero, and a closing ] in the memory that followed.
878    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
879        over the years. Originally (before any Unicode support), just the bottom 8
880        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
881        output from "man perlunicode" includes this:
883          The regular expression compiler produces polymorphic opcodes.  That
884          is, the pattern adapts to the data and automatically switches to
885          the Unicode character scheme when presented with Unicode data--or
886          instead uses a traditional byte scheme when presented with byte
887          data.
889        Sadly, a wide octal escape does not cause a switch, and in a string with
890        no other multibyte characters, these octal escapes are treated as before.
891        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
892        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
893        Unicode string.
895        I have not perpetrated such confusion in PCRE. Up till now, it took just
896        the bottom 8 bits, as in old Perl. I have now made octal escapes with
897        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
898        translate to the appropriate multibyte character.
900    29. Applied some refactoring to reduce the number of warnings from Microsoft
901        and Borland compilers. This has included removing the fudge introduced
902        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
903        a warning about an unused variable.
905    21. PCRE has not included VT (character 0x0b) in the set of whitespace
906        characters since release 4.0, because Perl (from release 5.004) does not.
907        [Or at least, is documented not to: some releases seem to be in conflict
908        with the documentation.] However, when a pattern was studied with
909        pcre_study() and all its branches started with \s, PCRE still included VT
910        as a possible starting character. Of course, this did no harm; it just
911        caused an unnecessary match attempt.
913    22. Removed a now-redundant internal flag bit that recorded the fact that case
914        dependency changed within the pattern. This was once needed for "required
915        byte" processing, but is no longer used. This recovers a now-scarce options
916        bit. Also moved the least significant internal flag bit to the most-
917        significant bit of the word, which was not previously used (hangover from
918        the days when it was an int rather than a uint) to free up another bit for
919        the future.
921    23. Added support for CRLF line endings as well as CR and LF. As well as the
922        default being selectable at build time, it can now be changed at runtime
923        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
924        specify that it is scanning data with non-default line endings.
926    24. Changed the definition of CXXLINK to make it agree with the definition of
927        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
929    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
930        recursions. This makes a big different to stack usage for some patterns.
932    26. If a subpattern containing a named recursion or subroutine reference such
933        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
934        the space required for the compiled pattern went wrong and gave too small a
935        value. Depending on the environment, this could lead to "Failed: internal
936        error: code overflow at offset 49" or "glibc detected double free or
937        corruption" errors.
939    27. Applied patches from Google (a) to support the new newline modes and (b) to
940        advance over multibyte UTF-8 characters in GlobalReplace.
942    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
943        difference for some implementation of PCRE in some Windows version.
945    29. Added some extra testing facilities to pcretest:
947        \q<number>   in a data line sets the "match limit" value
948        \Q<number>   in a data line sets the "match recursion limt" value
949        -S <number>  sets the stack size, where <number> is in megabytes
951        The -S option isn't available for Windows.
954    Version 6.6 06-Feb-06
955    ---------------------
957     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
958        in pcreposix.h. I have copied the definition from pcre.h.
960     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
961        because pcre.h is no longer a built file.
963     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
964        not normally included in the compiled code.
967  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
968  ---------------------  ---------------------

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