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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.3 09-Aug-07
5    ---------------------
7     1. In the rejigging of the build system that eventually resulted in 7.1, the
8        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
9        brackets there is not right, since it causes compilers to look for an
10        installed pcre.h, not the version that is in the source that is being
11        compiled (which of course may be different). I have changed it back to:
13          #include "pcre.h"
15        I have a vague recollection that the change was concerned with compiling in
16        different directories, but in the new build system, that is taken care of
17        by the VPATH setting the Makefile.
19     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
20        when the subject happened to end in the byte 0x85 (e.g. if the last
21        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
22        characters but of course it shouldn't be taken as a newline when it is part
23        of another character. The bug was that, for an unlimited repeat of . in
24        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
25        characters when looking for a newline.
27     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
29     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
30        in debug output.
32     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
33        long printing in the pcrecpp unittest when running under MinGW.
35     6. ESC_K was left out of the EBCDIC table.
37     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
38        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
39        limit also applies to "virtual nesting" when a pattern is recursive, and in
40        this case 1000 isn't so big. I have been able to remove this limit at the
41        expense of backing off one optimization in certain circumstances. Normally,
42        when pcre_exec() would call its internal match() function recursively and
43        immediately return the result unconditionally, it uses a "tail recursion"
44        feature to save stack. However, when a subpattern that can match an empty
45        string has an unlimited repetition quantifier, it no longer makes this
46        optimization. That gives it a stack frame in which to save the data for
47        checking that an empty string has been matched. Previously this was taken
48        from the 1000-entry workspace that had been reserved. So now there is no
49        explicit limit, but more stack is used.
51     8. Applied Daniel's patches to solve problems with the import/export magic
52        syntax that is required for Windows, and which was going wrong for the
53        pcreposix and pcrecpp parts of the library. These were overlooked when this
54        problem was solved for the main library.
56     9. There were some crude static tests to avoid integer overflow when computing
57        the size of patterns that contain repeated groups with explicit upper
58        limits. As the maximum quantifier is 65535, the maximum group length was
59        set at 30,000 so that the product of these two numbers did not overflow a
60        32-bit integer. However, it turns out that people want to use groups that
61        are longer than 30,000 bytes (though not repeat them that many times).
62        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
63        made it possible to implement the integer overflow checks in a much more
64        dynamic way, which I have now done. The artificial limitation on group
65        length has been removed - we now have only the limit on the total length of
66        the compiled pattern, which depends on the LINK_SIZE setting.
68    10. Fixed a bug in the documentation for get/copy named substring when
69        duplicate names are permitted. If none of the named substrings are set, the
70        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
71        empty string.
73    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
74        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
75        because the ] is interpreted as the first data character and the
76        terminating ] is not found. PCRE has been made compatible with Perl in this
77        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
78        cause memory overwriting.
80    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
81        string has been matched (to stop an infinite loop). It was not recognizing
82        a conditional subpattern that could match an empty string if that
83        subpattern was within another subpattern. For example, it looped when
84        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
85        condition was not nested. This bug has been fixed.
87    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
88        past the start of the subject in the presence of bytes with the top bit
89        set, for example "\x8aBCD".
91    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
92        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
94    14. Optimized (?!) to (*FAIL).
96    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
97        This restricts code points to be within the range 0 to 0x10FFFF, excluding
98        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
99        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
100        does: it's just the validity check that is more restrictive.
102    16. Inserted checks for integer overflows during escape sequence (backslash)
103        processing, and also fixed erroneous offset values for syntax errors during
104        backslash processing.
106    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
107        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
109    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
110        caused an overrun.
113    Version 7.2 19-Jun-07
114    ---------------------
116     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
117        which is apparently normally available under Windows.
119     2. Re-jig the pcregrep tests with different newline settings in an attempt
120        to make them independent of the local environment's newline setting.
122     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
124     4. Some of the "internals" tests were previously cut out when the link size
125        was not 2, because the output contained actual offsets. The recent new
126        "Z" feature of pcretest means that these can be cut out, making the tests
127        usable with all link sizes.
129     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
130        stack recursion. This gives a massive performance boost under BSD, but just
131        a small improvement under Linux. However, it saves one field in the frame
132        in all cases.
134     6. Added more features from the forthcoming Perl 5.10:
136        (a) (?-n) (where n is a string of digits) is a relative subroutine or
137            recursion call. It refers to the nth most recently opened parentheses.
139        (b) (?+n) is also a relative subroutine call; it refers to the nth next
140            to be opened parentheses.
142        (c) Conditions that refer to capturing parentheses can be specified
143            relatively, for example, (?(-2)... or (?(+3)...
145        (d) \K resets the start of the current match so that everything before
146            is not part of it.
148        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
150        (f) \g{name} is another synonym - part of Perl 5.10's unification of
151            reference syntax.
153        (g) (?| introduces a group in which the numbering of parentheses in each
154            alternative starts with the same number.
156        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
158     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
161     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
162        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
163        for detecting groups that can match an empty string.
165     9. A pattern with a very large number of alternatives (more than several
166        hundred) was running out of internal workspace during the pre-compile
167        phase, where pcre_compile() figures out how much memory will be needed. A
168        bit of new cunning has reduced the workspace needed for groups with
169        alternatives. The 1000-alternative test pattern now uses 12 bytes of
170        workspace instead of running out of the 4096 that are available.
172    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
174    11. Applied patch from Google to remove an optimization that didn't quite work.
175        The report of the bug said:
177          pcrecpp::RE("a*").FullMatch("aaa") matches, while
178          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
179          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
181    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
182        it matched the wrong number of bytes.
185    Version 7.1 24-Apr-07
186    ---------------------
188     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
189        that is more "standard", making use of automake and other Autotools. There
190        is some re-arrangement of the files and adjustment of comments consequent
191        on this.
193     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
194        for recursive directory scanning broke on some systems because the files
195        are not scanned in any specific order and on different systems the order
196        was different. A call to "sort" has been inserted into RunGrepTest for the
197        approprate test as a short-term fix. In the longer term there may be an
198        alternative.
200     3. I had an email from Eric Raymond about problems translating some of PCRE's
201        man pages to HTML (despite the fact that I distribute HTML pages, some
202        people do their own conversions for various reasons). The problems
203        concerned the use of low-level troff macros .br and .in. I have therefore
204        removed all such uses from the man pages (some were redundant, some could
205        be replaced by .nf/.fi pairs). The 132html script that I use to generate
206        HTML has been updated to handle .nf/.fi and to complain if it encounters
207        .br or .in.
209     4. Updated comments in configure.ac that get placed in config.h.in and also
210        arranged for config.h to be included in the distribution, with the name
211        config.h.generic, for the benefit of those who have to compile without
212        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
214     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
215        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
216        makevp.bat for the current PCRE, using the additional files
217        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
219     6. A Windows user reported a minor discrepancy with test 2, which turned out
220        to be caused by a trailing space on an input line that had got lost in his
221        copy. The trailing space was an accident, so I've just removed it.
223     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
224        that is needed.
226     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
227        as "const" (a) because they are and (b) because it helps the PHP
228        maintainers who have recently made a script to detect big data structures
229        in the php code that should be moved to the .rodata section. I remembered
230        to update Builducptable as well, so it won't revert if ucptable.h is ever
231        re-created.
233     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
234        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
235        order to be able to cut out the UTF-8 tables in the latter when UTF-8
236        support is not required. This saves 1.5-2K of code, which is important in
237        some applications.
239        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
240        so as not to refer to the tables, even though these functions will never be
241        called when UTF-8 support is disabled. Otherwise there are problems with a
242        shared library.
244    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
246        (a) It was defining its arguments as char * instead of void *.
248        (b) It was assuming that all moves were upwards in memory; this was true
249            a long time ago when I wrote it, but is no longer the case.
251        The emulated memove() is provided for those environments that have neither
252        memmove() nor bcopy(). I didn't think anyone used it these days, but that
253        is clearly not the case, as these two bugs were recently reported.
255    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
256        and Detrail to create the HTML documentation, the .txt form of the man
257        pages, and it removes trailing spaces from listed files. It also creates
258        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
259        case, it wraps all the #defines with #ifndefs. This script should be run
260        before "make dist".
262    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
263        with Unicode property support.
265        (a) For a maximizing quantifier, if the two different cases of the
266            character were of different lengths in their UTF-8 codings (there are
267            some cases like this - I found 11), and the matching function had to
268            back up over a mixture of the two cases, it incorrectly assumed they
269            were both the same length.
271        (b) When PCRE was configured to use the heap rather than the stack for
272            recursion during matching, it was not correctly preserving the data for
273            the other case of a UTF-8 character when checking ahead for a match
274            while processing a minimizing repeat. If the check also involved
275            matching a wide character, but failed, corruption could cause an
276            erroneous result when trying to check for a repeat of the original
277            character.
279    13. Some tidying changes to the testing mechanism:
281        (a) The RunTest script now detects the internal link size and whether there
282            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
283            values substituted by "configure". (The RunGrepTest script already did
284            this for UTF-8.) The configure.ac script no longer substitutes the
285            relevant variables.
287        (b) The debugging options /B and /D in pcretest show the compiled bytecode
288            with length and offset values. This means that the output is different
289            for different internal link sizes. Test 2 is skipped for link sizes
290            other than 2 because of this, bypassing the problem. Unfortunately,
291            there was also a test in test 3 (the locale tests) that used /B and
292            failed for link sizes other than 2. Rather than cut the whole test out,
293            I have added a new /Z option to pcretest that replaces the length and
294            offset values with spaces. This is now used to make test 3 independent
295            of link size. (Test 2 will be tidied up later.)
297    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
298        segmentation fault instead of returning the appropriate error message.
300    15. In multiline mode when the newline sequence was set to "any", the pattern
301        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
302        This doesn't seem right; it now treats the CRLF combination as the line
303        ending, and so does not match in that case. It's only a pattern such as ^$
304        that would hit this one: something like ^ABC$ would have failed after \r
305        and then tried again after \r\n.
307    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
308        in an attempt to make files that differ only in their line terminators
309        compare equal. This works on Linux.
311    17. Under certain error circumstances pcregrep might try to free random memory
312        as it exited. This is now fixed, thanks to valgrind.
314    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
315        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
316        was because its rules for how to advance for /g after matching an empty
317        string at the end of a line did not allow for this case. They now check for
318        it specially.
320    20. pcretest is supposed to handle patterns and data of any length, by
321        extending its buffers when necessary. It was getting this wrong when the
322        buffer for a data line had to be extended.
324    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
325        CRLF as a newline sequence.
327    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
328        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
329        I have nevertheless tidied it up.
331    23. Added some casts to kill warnings from HP-UX ia64 compiler.
333    24. Added a man page for pcre-config.
336    Version 7.0 19-Dec-06
337    ---------------------
339     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
340        moving to gcc 4.1.1.
342     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
343        sys/time.h, which is documented as needed for this function. It doesn't
344        seem to matter on Linux, but it showed up on some releases of OS X.
346     3. It seems that there are systems where bytes whose values are greater than
347        127 match isprint() in the "C" locale. The "C" locale should be the
348        default when a C program starts up. In most systems, only ASCII printing
349        characters match isprint(). This difference caused the output from pcretest
350        to vary, making some of the tests fail. I have changed pcretest so that:
352        (a) When it is outputting text in the compiled version of a pattern, bytes
353            other than 32-126 are always shown as hex escapes.
355        (b) When it is outputting text that is a matched part of a subject string,
356            it does the same, unless a different locale has been set for the match
357            (using the /L modifier). In this case, it uses isprint() to decide.
359     4. Fixed a major bug that caused incorrect computation of the amount of memory
360        required for a compiled pattern when options that changed within the
361        pattern affected the logic of the preliminary scan that determines the
362        length. The relevant options are -x, and -i in UTF-8 mode. The result was
363        that the computed length was too small. The symptoms of this bug were
364        either the PCRE error "internal error: code overflow" from pcre_compile(),
365        or a glibc crash with a message such as "pcretest: free(): invalid next
366        size (fast)". Examples of patterns that provoked this bug (shown in
367        pcretest format) are:
369          /(?-x: )/x
370          /(?x)(?-x: \s*#\s*)/
371          /((?i)[\x{c0}])/8
372          /(?i:[\x{c0}])/8
374        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
375        is now done differently.
377     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
378        wrapper classes; (b) implement a new function in the C++ scanner that is
379        more efficient than the old way of doing things because it avoids levels of
380        recursion in the regex matching; (c) add a paragraph to the documentation
381        for the FullMatch() function.
383     6. The escape sequence \n was being treated as whatever was defined as
384        "newline". Not only was this contrary to the documentation, which states
385        that \n is character 10 (hex 0A), but it also went horribly wrong when
386        "newline" was defined as CRLF. This has been fixed.
388     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
389        was being set to -1 for the "end of line" case (supposedly a value that no
390        character can have). Though this value is never used (the check for end of
391        line is "zero bytes in current character"), it caused compiler complaints.
392        I've changed it to 0xffffffff.
394     8. In pcre_version.c, the version string was being built by a sequence of
395        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
396        string (as it is for production releases) called a macro with an empty
397        argument. The C standard says the result of this is undefined. The gcc
398        compiler treats it as an empty string (which was what was wanted) but it is
399        reported that Visual C gives an error. The source has been hacked around to
400        avoid this problem.
402     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
403        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
404        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
405        of them did).
407    10. Originally, pcretest opened its input and output without "b"; then I was
408        told that "b" was needed in some environments, so it was added for release
409        5.0 to both the input and output. (It makes no difference on Unix-like
410        systems.) Later I was told that it is wrong for the input on Windows. I've
411        now abstracted the modes into two macros, to make it easier to fiddle with
412        them, and removed "b" from the input mode under Windows.
414    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
416    12. Added -help and --help to pcretest as an official way of being reminded
417        of the options.
419    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
420        and pcrecpp.cc because they annoy compilers at high warning levels.
422    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
424    15. Fixed an occurrence of == in configure.ac that should have been = (shell
425        scripts are not C programs :-) and which was not noticed because it works
426        on Linux.
428    16. pcretest is supposed to handle any length of pattern and data line (as one
429        line or as a continued sequence of lines) by extending its input buffer if
430        necessary. This feature was broken for very long pattern lines, leading to
431        a string of junk being passed to pcre_compile() if the pattern was longer
432        than about 50K.
434    17. I have done a major re-factoring of the way pcre_compile() computes the
435        amount of memory needed for a compiled pattern. Previously, there was code
436        that made a preliminary scan of the pattern in order to do this. That was
437        OK when PCRE was new, but as the facilities have expanded, it has become
438        harder and harder to keep it in step with the real compile phase, and there
439        have been a number of bugs (see for example, 4 above). I have now found a
440        cunning way of running the real compile function in a "fake" mode that
441        enables it to compute how much memory it would need, while actually only
442        ever using a few hundred bytes of working memory and without too many
443        tests of the mode. This should make future maintenance and development
444        easier. A side effect of this work is that the limit of 200 on the nesting
445        depth of parentheses has been removed (though this was never a serious
446        limitation, I suspect). However, there is a downside: pcre_compile() now
447        runs more slowly than before (30% or more, depending on the pattern). I
448        hope this isn't a big issue. There is no effect on runtime performance.
450    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
451        newline (only possible for the last line of a file) and it was a
452        pattern that set a locale (followed by /Lsomething), pcretest crashed.
454    19. Added additional timing features to pcretest. (1) The -tm option now times
455        matching only, not compiling. (2) Both -t and -tm can be followed, as a
456        separate command line item, by a number that specifies the number of
457        repeats to use when timing. The default is 50000; this gives better
458        precision, but takes uncomfortably long for very large patterns.
460    20. Extended pcre_study() to be more clever in cases where a branch of a
461        subpattern has no definite first character. For example, (a*|b*)[cd] would
462        previously give no result from pcre_study(). Now it recognizes that the
463        first character must be a, b, c, or d.
465    21. There was an incorrect error "recursive call could loop indefinitely" if
466        a subpattern (or the entire pattern) that was being tested for matching an
467        empty string contained only one non-empty item after a nested subpattern.
468        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
469        incorrectly, because the \d was being skipped in the check.
471    22. The pcretest program now has a new pattern option /B and a command line
472        option -b, which is equivalent to adding /B to every pattern. This causes
473        it to show the compiled bytecode, without the additional information that
474        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
475        is the same as /B/I).
477    23. A new optimization is now able automatically to treat some sequences such
478        as a*b as a*+b. More specifically, if something simple (such as a character
479        or a simple class like \d) has an unlimited quantifier, and is followed by
480        something that cannot possibly match the quantified thing, the quantifier
481        is automatically "possessified".
483    24. A recursive reference to a subpattern whose number was greater than 39
484        went wrong under certain circumstances in UTF-8 mode. This bug could also
485        have affected the operation of pcre_study().
487    25. Realized that a little bit of performance could be had by replacing
488        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
490    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
492    27. Possessive quantifiers such as a++ were previously implemented by turning
493        them into atomic groups such as ($>a+). Now they have their own opcodes,
494        which improves performance. This includes the automatically created ones
495        from 23 above.
497    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
498        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
499        the first matched character to be a colon. This applied both to named and
500        numbered groups.
502    29. The ucpinternal.h header file was missing its idempotency #ifdef.
504    30. I was sent a "project" file called libpcre.a.dev which I understand makes
505        building PCRE on Windows easier, so I have included it in the distribution.
507    31. There is now a check in pcretest against a ridiculously large number being
508        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
509        loop, the loop is abandoned.
511    32. Forward references to subpatterns in conditions such as (?(2)...) where
512        subpattern 2 is defined later cause pcre_compile() to search forwards in
513        the pattern for the relevant set of parentheses. This search went wrong
514        when there were unescaped parentheses in a character class, parentheses
515        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
517    33. "Subroutine" calls and backreferences were previously restricted to
518        referencing subpatterns earlier in the regex. This restriction has now
519        been removed.
521    34. Added a number of extra features that are going to be in Perl 5.10. On the
522        whole, these are just syntactic alternatives for features that PCRE had
523        previously implemented using the Python syntax or my own invention. The
524        other formats are all retained for compatibility.
526        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
527            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
528            also .NET compatible.
530        (b) A recursion or subroutine call to a named group can now be defined as
531            (?&name) as well as (?P>name).
533        (c) A backreference to a named group can now be defined as \k<name> or
534            \k'name' as well as (?P=name). The new forms, as well as being in Perl
535            5.10, are also .NET compatible.
537        (d) A conditional reference to a named group can now use the syntax
538            (?(<name>) or (?('name') as well as (?(name).
540        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
541            groups (named and numbered) that are never evaluated inline, but can be
542            called as "subroutines" from elsewhere. In effect, the DEFINE condition
543            is always false. There may be only one alternative in such a group.
545        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
546            as the simple (?(R). The condition is true only if the most recent
547            recursion is that of the given number or name. It does not search out
548            through the entire recursion stack.
550        (g) The escape \gN or \g{N} has been added, where N is a positive or
551            negative number, specifying an absolute or relative reference.
553    35. Tidied to get rid of some further signed/unsigned compiler warnings and
554        some "unreachable code" warnings.
556    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
557        things, this adds five new scripts.
559    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
560        There were also incompatibilities regarding the handling of \Q..\E inside
561        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
562        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
564    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
565        matches an empty string, and forcibly breaks the loop. There were bugs in
566        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
567        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
568        separate and independent bugs (that affected different cases) have been
569        fixed.
571    39. Refactored the code to abolish the use of different opcodes for small
572        capturing bracket numbers. This is a tidy that I avoided doing when I
573        removed the limit on the number of capturing brackets for 3.5 back in 2001.
574        The new approach is not only tidier, it makes it possible to reduce the
575        memory needed to fix the previous bug (38).
577    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
578        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
579        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
580        mode.
582    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
583        report.
585    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
586        copy construction and assignment in the C++ wrapper.
588    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
589        couple of bugs that could have given wrong results in the "--newline=crlf"
590        case.
592    44. Added a number of casts and did some reorganization of signed/unsigned int
593        variables following suggestions from Dair Grant. Also renamed the variable
594        "this" as "item" because it is a C++ keyword.
596    45. Arranged for dftables to add
598          #include "pcre_internal.h"
600        to pcre_chartables.c because without it, gcc 4.x may remove the array
601        definition from the final binary if PCRE is built into a static library and
602        dead code stripping is activated.
604    46. For an unanchored pattern, if a match attempt fails at the start of a
605        newline sequence, and the newline setting is CRLF or ANY, and the next two
606        characters are CRLF, advance by two characters instead of one.
609    Version 6.7 04-Jul-06
610    ---------------------
612     1. In order to handle tests when input lines are enormously long, pcretest has
613        been re-factored so that it automatically extends its buffers when
614        necessary. The code is crude, but this _is_ just a test program. The
615        default size has been increased from 32K to 50K.
617     2. The code in pcre_study() was using the value of the re argument before
618        testing it for NULL. (Of course, in any sensible call of the function, it
619        won't be NULL.)
621     3. The memmove() emulation function in pcre_internal.h, which is used on
622        systems that lack both memmove() and bcopy() - that is, hardly ever -
623        was missing a "static" storage class specifier.
625     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
626        containing an extended class (one that cannot be represented by a bitmap
627        because it contains high-valued characters or Unicode property items, e.g.
628        [\pZ]). Almost always one would set UTF-8 mode when processing such a
629        pattern, but PCRE should not loop if you do not (it no longer does).
630        [Detail: two cases were found: (a) a repeated subpattern containing an
631        extended class; (b) a recursive reference to a subpattern that followed a
632        previous extended class. It wasn't skipping over the extended class
633        correctly when UTF-8 mode was not set.]
635     5. A negated single-character class was not being recognized as fixed-length
636        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
637        compile error "lookbehind assertion is not fixed length".
639     6. The RunPerlTest auxiliary script was showing an unexpected difference
640        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
641        write a Perl script that can interpret lines of an input file either as
642        byte characters or as UTF-8, which is what "perltest" was being required to
643        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
644        can't do is switch easily at run time between having the "use utf8;" pragma
645        or not. In the end, I fudged it by using the RunPerlTest script to insert
646        "use utf8;" explicitly for the UTF-8 tests.
648     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
649        the end of the subject string, contrary to the documentation and to what
650        Perl does. This was true of both matching functions. Now it matches only at
651        the start of the subject and immediately after *internal* newlines.
653     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
654        a pointer to an int instead of a pointer to an unsigned long int. This
655        caused problems on 64-bit systems.
657     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
658        instance of the 'standard' template library not being so standard".
660    10. There was no check on the number of named subpatterns nor the maximum
661        length of a subpattern name. The product of these values is used to compute
662        the size of the memory block for a compiled pattern. By supplying a very
663        long subpattern name and a large number of named subpatterns, the size
664        computation could be caused to overflow. This is now prevented by limiting
665        the length of names to 32 characters, and the number of named subpatterns
666        to 10,000.
668    11. Subpatterns that are repeated with specific counts have to be replicated in
669        the compiled pattern. The size of memory for this was computed from the
670        length of the subpattern and the repeat count. The latter is limited to
671        65535, but there was no limit on the former, meaning that integer overflow
672        could in principle occur. The compiled length of a repeated subpattern is
673        now limited to 30,000 bytes in order to prevent this.
675    12. Added the optional facility to have named substrings with the same name.
677    13. Added the ability to use a named substring as a condition, using the
678        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
679        are numbers (not recommended). Forward references are permitted.
681    14. Added forward references in named backreferences (if you see what I mean).
683    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
684        pattern could run off the end of the subject. For example, the pattern
685        "(?s)(.{1,5})"8 did this with the subject "ab".
687    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
688        PCRE_CASELESS was set when matching characters that were quantified with ?
689        or *.
691    17. A character class other than a single negated character that had a minimum
692        but no maximum quantifier - for example [ab]{6,} - was not handled
693        correctly by pce_dfa_exec(). It would match only one character.
695    18. A valid (though odd) pattern that looked like a POSIX character
696        class but used an invalid character after [ (for example [[,abc,]]) caused
697        pcre_compile() to give the error "Failed: internal error: code overflow" or
698        in some cases to crash with a glibc free() error. This could even happen if
699        the pattern terminated after [[ but there just happened to be a sequence of
700        letters, a binary zero, and a closing ] in the memory that followed.
702    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
703        over the years. Originally (before any Unicode support), just the bottom 8
704        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
705        output from "man perlunicode" includes this:
707          The regular expression compiler produces polymorphic opcodes.  That
708          is, the pattern adapts to the data and automatically switches to
709          the Unicode character scheme when presented with Unicode data--or
710          instead uses a traditional byte scheme when presented with byte
711          data.
713        Sadly, a wide octal escape does not cause a switch, and in a string with
714        no other multibyte characters, these octal escapes are treated as before.
715        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
716        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
717        Unicode string.
719        I have not perpetrated such confusion in PCRE. Up till now, it took just
720        the bottom 8 bits, as in old Perl. I have now made octal escapes with
721        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
722        translate to the appropriate multibyte character.
724    29. Applied some refactoring to reduce the number of warnings from Microsoft
725        and Borland compilers. This has included removing the fudge introduced
726        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
727        a warning about an unused variable.
729    21. PCRE has not included VT (character 0x0b) in the set of whitespace
730        characters since release 4.0, because Perl (from release 5.004) does not.
731        [Or at least, is documented not to: some releases seem to be in conflict
732        with the documentation.] However, when a pattern was studied with
733        pcre_study() and all its branches started with \s, PCRE still included VT
734        as a possible starting character. Of course, this did no harm; it just
735        caused an unnecessary match attempt.
737    22. Removed a now-redundant internal flag bit that recorded the fact that case
738        dependency changed within the pattern. This was once needed for "required
739        byte" processing, but is no longer used. This recovers a now-scarce options
740        bit. Also moved the least significant internal flag bit to the most-
741        significant bit of the word, which was not previously used (hangover from
742        the days when it was an int rather than a uint) to free up another bit for
743        the future.
745    23. Added support for CRLF line endings as well as CR and LF. As well as the
746        default being selectable at build time, it can now be changed at runtime
747        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
748        specify that it is scanning data with non-default line endings.
750    24. Changed the definition of CXXLINK to make it agree with the definition of
751        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
753    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
754        recursions. This makes a big different to stack usage for some patterns.
756    26. If a subpattern containing a named recursion or subroutine reference such
757        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
758        the space required for the compiled pattern went wrong and gave too small a
759        value. Depending on the environment, this could lead to "Failed: internal
760        error: code overflow at offset 49" or "glibc detected double free or
761        corruption" errors.
763    27. Applied patches from Google (a) to support the new newline modes and (b) to
764        advance over multibyte UTF-8 characters in GlobalReplace.
766    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
767        difference for some implementation of PCRE in some Windows version.
769    29. Added some extra testing facilities to pcretest:
771        \q<number>   in a data line sets the "match limit" value
772        \Q<number>   in a data line sets the "match recursion limt" value
773        -S <number>  sets the stack size, where <number> is in megabytes
775        The -S option isn't available for Windows.
778    Version 6.6 06-Feb-06
779    ---------------------
781     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
782        in pcreposix.h. I have copied the definition from pcre.h.
784     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
785        because pcre.h is no longer a built file.
787     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
788        not normally included in the compiled code.
791    Version 6.5 01-Feb-06
792    ---------------------
794     1. When using the partial match feature with pcre_dfa_exec(), it was not
795        anchoring the second and subsequent partial matches at the new starting
796        point. This could lead to incorrect results. For example, with the pattern
797        /1234/, partially matching against "123" and then "a4" gave a match.
799     2. Changes to pcregrep:
801        (a) All non-match returns from pcre_exec() were being treated as failures
802            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
803            error message is output. Some extra information is given for the
804            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
805            probably the only errors that are likely to be caused by users (by
806            specifying a regex that has nested indefinite repeats, for instance).
807            If there are more than 20 of these errors, pcregrep is abandoned.
809        (b) A binary zero was treated as data while matching, but terminated the
810            output line if it was written out. This has been fixed: binary zeroes
811            are now no different to any other data bytes.
813        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
814            used to set a locale for matching. The --locale=xxxx long option has
815            been added (no short equivalent) to specify a locale explicitly on the
816            pcregrep command, overriding the environment variables.
818        (d) When -B was used with -n, some line numbers in the output were one less
819            than they should have been.
821        (e) Added the -o (--only-matching) option.
823        (f) If -A or -C was used with -c (count only), some lines of context were
824            accidentally printed for the final match.
826        (g) Added the -H (--with-filename) option.
828        (h) The combination of options -rh failed to suppress file names for files
829            that were found from directory arguments.
831        (i) Added the -D (--devices) and -d (--directories) options.
833        (j) Added the -F (--fixed-strings) option.
835        (k) Allow "-" to be used as a file name for -f as well as for a data file.
837        (l) Added the --colo(u)r option.
839        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
840            is not present by default.
842     3. A nasty bug was discovered in the handling of recursive patterns, that is,
843        items such as (?R) or (?1), when the recursion could match a number of
844        alternatives. If it matched one of the alternatives, but subsequently,
845        outside the recursion, there was a failure, the code tried to back up into
846        the recursion. However, because of the way PCRE is implemented, this is not
847        possible, and the result was an incorrect result from the match.
849        In order to prevent this happening, the specification of recursion has
850        been changed so that all such subpatterns are automatically treated as
851        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
853     4. I had overlooked the fact that, in some locales, there are characters for
854        which isalpha() is true but neither isupper() nor islower() are true. In
855        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
856        and ordfeminine) are like this. This affected the treatment of \w and \W
857        when they appeared in character classes, but not when they appeared outside
858        a character class. The bit map for "word" characters is now created
859        separately from the results of isalnum() instead of just taking it from the
860        upper, lower, and digit maps. (Plus the underscore character, of course.)
862     5. The above bug also affected the handling of POSIX character classes such as
863        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
864        permanent tables. Instead, the bit maps for such a class were previously
865        created as the appropriate unions of the upper, lower, and digit bitmaps.
866        Now they are created by subtraction from the [[:word:]] class, which has
867        its own bitmap.
869     6. The [[:blank:]] character class matches horizontal, but not vertical space.
870        It is created by subtracting the vertical space characters (\x09, \x0a,
871        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
872        subtraction was done in the overall bitmap for a character class, meaning
873        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
874        be recognized. This bug has been fixed.
876     7. Patches from the folks at Google:
878          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
879          real life, but is still worth protecting against".
881          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
882          regular expressions".
884          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
885          have it.
887          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
888          "configure" and the latter not, in order to fix a problem somebody had
889          with compiling the Arg class on HP-UX.
891          (e) Improve the error-handling of the C++ wrapper a little bit.
893          (f) New tests for checking recursion limiting.
895     8. The pcre_memmove() function, which is used only if the environment does not
896        have a standard memmove() function (and is therefore rarely compiled),
897        contained two bugs: (a) use of int instead of size_t, and (b) it was not
898        returning a result (though PCRE never actually uses the result).
900     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
901        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
902        returned instead of calling malloc() with an overflowing number that would
903        most likely cause subsequent chaos.
905    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
907    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
908        with this option is matched, the nmatch and pmatch options of regexec() are
909        ignored.
911    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
912        provided in case anyone wants to the the POSIX interface with UTF-8
913        strings.
915    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
916        C++ linking (needed for some HP-UX environments).
918    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
919        (unused parameter) and in the pcre_printint() function (omitted "default"
920        switch label when the default is to do nothing).
922    15. Added some code to make it possible, when PCRE is compiled as a C++
923        library, to replace subject pointers for pcre_exec() with a smart pointer
924        class, thus making it possible to process discontinuous strings.
926    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
927        much the same function. They were added by different people who were trying
928        to make PCRE easy to compile on non-Unix systems. It has been suggested
929        that PCRE_EXPORT be abolished now that there is more automatic apparatus
930        for compiling on Windows systems. I have therefore replaced it with
931        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
932        defaults to "extern" for C or "extern C" for C++, which works fine on
933        Unix-like systems. It is now possible to override the value of PCRE_DATA_
934        SCOPE with something explicit in config.h. In addition:
936        (a) pcreposix.h still had just "extern" instead of either of these macros;
937            I have replaced it with PCRE_DATA_SCOPE.
939        (b) Functions such as _pcre_xclass(), which are internal to the library,
940            but external in the C sense, all had PCRE_EXPORT in their definitions.
941            This is apparently wrong for the Windows case, so I have removed it.
942            (It makes no difference on Unix-like systems.)
944    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
945        of recursive calls to match(). This is different to MATCH_LIMIT because
946        that limits the total number of calls to match(), not all of which increase
947        the depth of recursion. Limiting the recursion depth limits the amount of
948        stack (or heap if NO_RECURSE is set) that is used. The default can be set
949        when PCRE is compiled, and changed at run time. A patch from Google adds
950        this functionality to the C++ interface.
952    18. Changes to the handling of Unicode character properties:
954        (a) Updated the table to Unicode 4.1.0.
956        (b) Recognize characters that are not in the table as "Cn" (undefined).
958        (c) I revised the way the table is implemented to a much improved format
959            which includes recognition of ranges. It now supports the ranges that
960            are defined in UnicodeData.txt, and it also amalgamates other
961            characters into ranges. This has reduced the number of entries in the
962            table from around 16,000 to around 3,000, thus reducing its size
963            considerably. I realized I did not need to use a tree structure after
964            all - a binary chop search is just as efficient. Having reduced the
965            number of entries, I extended their size from 6 bytes to 8 bytes to
966            allow for more data.
968        (d) Added support for Unicode script names via properties such as \p{Han}.
970    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
971        matching that character.
973    20. When matching a repeated Unicode property with a minimum greater than zero,
974        (for example \pL{2,}), PCRE could look past the end of the subject if it
975        reached it while seeking the minimum number of characters. This could
976        happen only if some of the characters were more than one byte long, because
977        there is a check for at least the minimum number of bytes.
979    21. Refactored the implementation of \p and \P so as to be more general, to
980        allow for more different types of property in future. This has changed the
981        compiled form incompatibly. Anybody with saved compiled patterns that use
982        \p or \P will have to recompile them.
984    22. Added "Any" and "L&" to the supported property types.
986    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
987        but give a compile time error if the value is greater than 0xff.
989    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
990        accidentally not being installed or uninstalled.
992    25. The pcre.h file was built from pcre.h.in, but the only changes that were
993        made were to insert the current release number. This seemed silly, because
994        it made things harder for people building PCRE on systems that don't run
995        "configure". I have turned pcre.h into a distributed file, no longer built
996        by "configure", with the version identification directly included. There is
997        no longer a pcre.h.in file.
999        However, this change necessitated a change to the pcre-config script as
1000        well. It is built from pcre-config.in, and one of the substitutions was the
1001        release number. I have updated configure.ac so that ./configure now finds
1002        the release number by grepping pcre.h.
1004    26. Added the ability to run the tests under valgrind.
1007    Version 6.4 05-Sep-05
1008    ---------------------
1010     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1011        "--" to be printed when multiple files were scanned, even when none of the
1012        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1013        consider it to be a bug, and have restored the previous behaviour.
1015     2. A couple of code tidies to get rid of compiler warnings.
1017     3. The pcretest program used to cheat by referring to symbols in the library
1018        whose names begin with _pcre_. These are internal symbols that are not
1019        really supposed to be visible externally, and in some environments it is
1020        possible to suppress them. The cheating is now confined to including
1021        certain files from the library's source, which is a bit cleaner.
1023     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1024        file's purpose clearer.
1026     5. Reorganized pcre_ucp_findchar().
1029  Version 6.3 15-Aug-05  Version 6.3 15-Aug-05
1030  ---------------------  ---------------------

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