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revision 83 by nigel, Sat Feb 24 21:41:06 2007 UTC revision 206 by ph10, Fri Aug 3 14:53:04 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.3 05-Jul-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.
88    Version 7.2 19-Jun-07
89    ---------------------
91     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
92        which is apparently normally available under Windows.
94     2. Re-jig the pcregrep tests with different newline settings in an attempt
95        to make them independent of the local environment's newline setting.
97     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
99     4. Some of the "internals" tests were previously cut out when the link size
100        was not 2, because the output contained actual offsets. The recent new
101        "Z" feature of pcretest means that these can be cut out, making the tests
102        usable with all link sizes.
104     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
105        stack recursion. This gives a massive performance boost under BSD, but just
106        a small improvement under Linux. However, it saves one field in the frame
107        in all cases.
109     6. Added more features from the forthcoming Perl 5.10:
111        (a) (?-n) (where n is a string of digits) is a relative subroutine or
112            recursion call. It refers to the nth most recently opened parentheses.
114        (b) (?+n) is also a relative subroutine call; it refers to the nth next
115            to be opened parentheses.
117        (c) Conditions that refer to capturing parentheses can be specified
118            relatively, for example, (?(-2)... or (?(+3)...
120        (d) \K resets the start of the current match so that everything before
121            is not part of it.
123        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
125        (f) \g{name} is another synonym - part of Perl 5.10's unification of
126            reference syntax.
128        (g) (?| introduces a group in which the numbering of parentheses in each
129            alternative starts with the same number.
131        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
133     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
136     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
137        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
138        for detecting groups that can match an empty string.
140     9. A pattern with a very large number of alternatives (more than several
141        hundred) was running out of internal workspace during the pre-compile
142        phase, where pcre_compile() figures out how much memory will be needed. A
143        bit of new cunning has reduced the workspace needed for groups with
144        alternatives. The 1000-alternative test pattern now uses 12 bytes of
145        workspace instead of running out of the 4096 that are available.
147    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
149    11. Applied patch from Google to remove an optimization that didn't quite work.
150        The report of the bug said:
152          pcrecpp::RE("a*").FullMatch("aaa") matches, while
153          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
154          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
156    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
157        it matched the wrong number of bytes.
160    Version 7.1 24-Apr-07
161    ---------------------
163     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
164        that is more "standard", making use of automake and other Autotools. There
165        is some re-arrangement of the files and adjustment of comments consequent
166        on this.
168     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
169        for recursive directory scanning broke on some systems because the files
170        are not scanned in any specific order and on different systems the order
171        was different. A call to "sort" has been inserted into RunGrepTest for the
172        approprate test as a short-term fix. In the longer term there may be an
173        alternative.
175     3. I had an email from Eric Raymond about problems translating some of PCRE's
176        man pages to HTML (despite the fact that I distribute HTML pages, some
177        people do their own conversions for various reasons). The problems
178        concerned the use of low-level troff macros .br and .in. I have therefore
179        removed all such uses from the man pages (some were redundant, some could
180        be replaced by .nf/.fi pairs). The 132html script that I use to generate
181        HTML has been updated to handle .nf/.fi and to complain if it encounters
182        .br or .in.
184     4. Updated comments in configure.ac that get placed in config.h.in and also
185        arranged for config.h to be included in the distribution, with the name
186        config.h.generic, for the benefit of those who have to compile without
187        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
189     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
190        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
191        makevp.bat for the current PCRE, using the additional files
192        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
194     6. A Windows user reported a minor discrepancy with test 2, which turned out
195        to be caused by a trailing space on an input line that had got lost in his
196        copy. The trailing space was an accident, so I've just removed it.
198     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
199        that is needed.
201     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
202        as "const" (a) because they are and (b) because it helps the PHP
203        maintainers who have recently made a script to detect big data structures
204        in the php code that should be moved to the .rodata section. I remembered
205        to update Builducptable as well, so it won't revert if ucptable.h is ever
206        re-created.
208     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
209        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
210        order to be able to cut out the UTF-8 tables in the latter when UTF-8
211        support is not required. This saves 1.5-2K of code, which is important in
212        some applications.
214        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
215        so as not to refer to the tables, even though these functions will never be
216        called when UTF-8 support is disabled. Otherwise there are problems with a
217        shared library.
219    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
221        (a) It was defining its arguments as char * instead of void *.
223        (b) It was assuming that all moves were upwards in memory; this was true
224            a long time ago when I wrote it, but is no longer the case.
226        The emulated memove() is provided for those environments that have neither
227        memmove() nor bcopy(). I didn't think anyone used it these days, but that
228        is clearly not the case, as these two bugs were recently reported.
230    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
231        and Detrail to create the HTML documentation, the .txt form of the man
232        pages, and it removes trailing spaces from listed files. It also creates
233        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
234        case, it wraps all the #defines with #ifndefs. This script should be run
235        before "make dist".
237    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
238        with Unicode property support.
240        (a) For a maximizing quantifier, if the two different cases of the
241            character were of different lengths in their UTF-8 codings (there are
242            some cases like this - I found 11), and the matching function had to
243            back up over a mixture of the two cases, it incorrectly assumed they
244            were both the same length.
246        (b) When PCRE was configured to use the heap rather than the stack for
247            recursion during matching, it was not correctly preserving the data for
248            the other case of a UTF-8 character when checking ahead for a match
249            while processing a minimizing repeat. If the check also involved
250            matching a wide character, but failed, corruption could cause an
251            erroneous result when trying to check for a repeat of the original
252            character.
254    13. Some tidying changes to the testing mechanism:
256        (a) The RunTest script now detects the internal link size and whether there
257            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
258            values substituted by "configure". (The RunGrepTest script already did
259            this for UTF-8.) The configure.ac script no longer substitutes the
260            relevant variables.
262        (b) The debugging options /B and /D in pcretest show the compiled bytecode
263            with length and offset values. This means that the output is different
264            for different internal link sizes. Test 2 is skipped for link sizes
265            other than 2 because of this, bypassing the problem. Unfortunately,
266            there was also a test in test 3 (the locale tests) that used /B and
267            failed for link sizes other than 2. Rather than cut the whole test out,
268            I have added a new /Z option to pcretest that replaces the length and
269            offset values with spaces. This is now used to make test 3 independent
270            of link size. (Test 2 will be tidied up later.)
272    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
273        segmentation fault instead of returning the appropriate error message.
275    15. In multiline mode when the newline sequence was set to "any", the pattern
276        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
277        This doesn't seem right; it now treats the CRLF combination as the line
278        ending, and so does not match in that case. It's only a pattern such as ^$
279        that would hit this one: something like ^ABC$ would have failed after \r
280        and then tried again after \r\n.
282    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
283        in an attempt to make files that differ only in their line terminators
284        compare equal. This works on Linux.
286    17. Under certain error circumstances pcregrep might try to free random memory
287        as it exited. This is now fixed, thanks to valgrind.
289    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
290        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
291        was because its rules for how to advance for /g after matching an empty
292        string at the end of a line did not allow for this case. They now check for
293        it specially.
295    20. pcretest is supposed to handle patterns and data of any length, by
296        extending its buffers when necessary. It was getting this wrong when the
297        buffer for a data line had to be extended.
299    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
300        CRLF as a newline sequence.
302    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
303        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
304        I have nevertheless tidied it up.
306    23. Added some casts to kill warnings from HP-UX ia64 compiler.
308    24. Added a man page for pcre-config.
311    Version 7.0 19-Dec-06
312    ---------------------
314     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
315        moving to gcc 4.1.1.
317     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
318        sys/time.h, which is documented as needed for this function. It doesn't
319        seem to matter on Linux, but it showed up on some releases of OS X.
321     3. It seems that there are systems where bytes whose values are greater than
322        127 match isprint() in the "C" locale. The "C" locale should be the
323        default when a C program starts up. In most systems, only ASCII printing
324        characters match isprint(). This difference caused the output from pcretest
325        to vary, making some of the tests fail. I have changed pcretest so that:
327        (a) When it is outputting text in the compiled version of a pattern, bytes
328            other than 32-126 are always shown as hex escapes.
330        (b) When it is outputting text that is a matched part of a subject string,
331            it does the same, unless a different locale has been set for the match
332            (using the /L modifier). In this case, it uses isprint() to decide.
334     4. Fixed a major bug that caused incorrect computation of the amount of memory
335        required for a compiled pattern when options that changed within the
336        pattern affected the logic of the preliminary scan that determines the
337        length. The relevant options are -x, and -i in UTF-8 mode. The result was
338        that the computed length was too small. The symptoms of this bug were
339        either the PCRE error "internal error: code overflow" from pcre_compile(),
340        or a glibc crash with a message such as "pcretest: free(): invalid next
341        size (fast)". Examples of patterns that provoked this bug (shown in
342        pcretest format) are:
344          /(?-x: )/x
345          /(?x)(?-x: \s*#\s*)/
346          /((?i)[\x{c0}])/8
347          /(?i:[\x{c0}])/8
349        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
350        is now done differently.
352     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
353        wrapper classes; (b) implement a new function in the C++ scanner that is
354        more efficient than the old way of doing things because it avoids levels of
355        recursion in the regex matching; (c) add a paragraph to the documentation
356        for the FullMatch() function.
358     6. The escape sequence \n was being treated as whatever was defined as
359        "newline". Not only was this contrary to the documentation, which states
360        that \n is character 10 (hex 0A), but it also went horribly wrong when
361        "newline" was defined as CRLF. This has been fixed.
363     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
364        was being set to -1 for the "end of line" case (supposedly a value that no
365        character can have). Though this value is never used (the check for end of
366        line is "zero bytes in current character"), it caused compiler complaints.
367        I've changed it to 0xffffffff.
369     8. In pcre_version.c, the version string was being built by a sequence of
370        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
371        string (as it is for production releases) called a macro with an empty
372        argument. The C standard says the result of this is undefined. The gcc
373        compiler treats it as an empty string (which was what was wanted) but it is
374        reported that Visual C gives an error. The source has been hacked around to
375        avoid this problem.
377     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
378        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
379        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
380        of them did).
382    10. Originally, pcretest opened its input and output without "b"; then I was
383        told that "b" was needed in some environments, so it was added for release
384        5.0 to both the input and output. (It makes no difference on Unix-like
385        systems.) Later I was told that it is wrong for the input on Windows. I've
386        now abstracted the modes into two macros, to make it easier to fiddle with
387        them, and removed "b" from the input mode under Windows.
389    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
391    12. Added -help and --help to pcretest as an official way of being reminded
392        of the options.
394    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
395        and pcrecpp.cc because they annoy compilers at high warning levels.
397    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
399    15. Fixed an occurrence of == in configure.ac that should have been = (shell
400        scripts are not C programs :-) and which was not noticed because it works
401        on Linux.
403    16. pcretest is supposed to handle any length of pattern and data line (as one
404        line or as a continued sequence of lines) by extending its input buffer if
405        necessary. This feature was broken for very long pattern lines, leading to
406        a string of junk being passed to pcre_compile() if the pattern was longer
407        than about 50K.
409    17. I have done a major re-factoring of the way pcre_compile() computes the
410        amount of memory needed for a compiled pattern. Previously, there was code
411        that made a preliminary scan of the pattern in order to do this. That was
412        OK when PCRE was new, but as the facilities have expanded, it has become
413        harder and harder to keep it in step with the real compile phase, and there
414        have been a number of bugs (see for example, 4 above). I have now found a
415        cunning way of running the real compile function in a "fake" mode that
416        enables it to compute how much memory it would need, while actually only
417        ever using a few hundred bytes of working memory and without too many
418        tests of the mode. This should make future maintenance and development
419        easier. A side effect of this work is that the limit of 200 on the nesting
420        depth of parentheses has been removed (though this was never a serious
421        limitation, I suspect). However, there is a downside: pcre_compile() now
422        runs more slowly than before (30% or more, depending on the pattern). I
423        hope this isn't a big issue. There is no effect on runtime performance.
425    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
426        newline (only possible for the last line of a file) and it was a
427        pattern that set a locale (followed by /Lsomething), pcretest crashed.
429    19. Added additional timing features to pcretest. (1) The -tm option now times
430        matching only, not compiling. (2) Both -t and -tm can be followed, as a
431        separate command line item, by a number that specifies the number of
432        repeats to use when timing. The default is 50000; this gives better
433        precision, but takes uncomfortably long for very large patterns.
435    20. Extended pcre_study() to be more clever in cases where a branch of a
436        subpattern has no definite first character. For example, (a*|b*)[cd] would
437        previously give no result from pcre_study(). Now it recognizes that the
438        first character must be a, b, c, or d.
440    21. There was an incorrect error "recursive call could loop indefinitely" if
441        a subpattern (or the entire pattern) that was being tested for matching an
442        empty string contained only one non-empty item after a nested subpattern.
443        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
444        incorrectly, because the \d was being skipped in the check.
446    22. The pcretest program now has a new pattern option /B and a command line
447        option -b, which is equivalent to adding /B to every pattern. This causes
448        it to show the compiled bytecode, without the additional information that
449        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
450        is the same as /B/I).
452    23. A new optimization is now able automatically to treat some sequences such
453        as a*b as a*+b. More specifically, if something simple (such as a character
454        or a simple class like \d) has an unlimited quantifier, and is followed by
455        something that cannot possibly match the quantified thing, the quantifier
456        is automatically "possessified".
458    24. A recursive reference to a subpattern whose number was greater than 39
459        went wrong under certain circumstances in UTF-8 mode. This bug could also
460        have affected the operation of pcre_study().
462    25. Realized that a little bit of performance could be had by replacing
463        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
465    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
467    27. Possessive quantifiers such as a++ were previously implemented by turning
468        them into atomic groups such as ($>a+). Now they have their own opcodes,
469        which improves performance. This includes the automatically created ones
470        from 23 above.
472    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
473        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
474        the first matched character to be a colon. This applied both to named and
475        numbered groups.
477    29. The ucpinternal.h header file was missing its idempotency #ifdef.
479    30. I was sent a "project" file called libpcre.a.dev which I understand makes
480        building PCRE on Windows easier, so I have included it in the distribution.
482    31. There is now a check in pcretest against a ridiculously large number being
483        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
484        loop, the loop is abandoned.
486    32. Forward references to subpatterns in conditions such as (?(2)...) where
487        subpattern 2 is defined later cause pcre_compile() to search forwards in
488        the pattern for the relevant set of parentheses. This search went wrong
489        when there were unescaped parentheses in a character class, parentheses
490        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
492    33. "Subroutine" calls and backreferences were previously restricted to
493        referencing subpatterns earlier in the regex. This restriction has now
494        been removed.
496    34. Added a number of extra features that are going to be in Perl 5.10. On the
497        whole, these are just syntactic alternatives for features that PCRE had
498        previously implemented using the Python syntax or my own invention. The
499        other formats are all retained for compatibility.
501        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
502            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
503            also .NET compatible.
505        (b) A recursion or subroutine call to a named group can now be defined as
506            (?&name) as well as (?P>name).
508        (c) A backreference to a named group can now be defined as \k<name> or
509            \k'name' as well as (?P=name). The new forms, as well as being in Perl
510            5.10, are also .NET compatible.
512        (d) A conditional reference to a named group can now use the syntax
513            (?(<name>) or (?('name') as well as (?(name).
515        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
516            groups (named and numbered) that are never evaluated inline, but can be
517            called as "subroutines" from elsewhere. In effect, the DEFINE condition
518            is always false. There may be only one alternative in such a group.
520        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
521            as the simple (?(R). The condition is true only if the most recent
522            recursion is that of the given number or name. It does not search out
523            through the entire recursion stack.
525        (g) The escape \gN or \g{N} has been added, where N is a positive or
526            negative number, specifying an absolute or relative reference.
528    35. Tidied to get rid of some further signed/unsigned compiler warnings and
529        some "unreachable code" warnings.
531    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
532        things, this adds five new scripts.
534    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
535        There were also incompatibilities regarding the handling of \Q..\E inside
536        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
537        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
539    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
540        matches an empty string, and forcibly breaks the loop. There were bugs in
541        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
542        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
543        separate and independent bugs (that affected different cases) have been
544        fixed.
546    39. Refactored the code to abolish the use of different opcodes for small
547        capturing bracket numbers. This is a tidy that I avoided doing when I
548        removed the limit on the number of capturing brackets for 3.5 back in 2001.
549        The new approach is not only tidier, it makes it possible to reduce the
550        memory needed to fix the previous bug (38).
552    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
553        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
554        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
555        mode.
557    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
558        report.
560    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
561        copy construction and assignment in the C++ wrapper.
563    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
564        couple of bugs that could have given wrong results in the "--newline=crlf"
565        case.
567    44. Added a number of casts and did some reorganization of signed/unsigned int
568        variables following suggestions from Dair Grant. Also renamed the variable
569        "this" as "item" because it is a C++ keyword.
571    45. Arranged for dftables to add
573          #include "pcre_internal.h"
575        to pcre_chartables.c because without it, gcc 4.x may remove the array
576        definition from the final binary if PCRE is built into a static library and
577        dead code stripping is activated.
579    46. For an unanchored pattern, if a match attempt fails at the start of a
580        newline sequence, and the newline setting is CRLF or ANY, and the next two
581        characters are CRLF, advance by two characters instead of one.
584    Version 6.7 04-Jul-06
585    ---------------------
587     1. In order to handle tests when input lines are enormously long, pcretest has
588        been re-factored so that it automatically extends its buffers when
589        necessary. The code is crude, but this _is_ just a test program. The
590        default size has been increased from 32K to 50K.
592     2. The code in pcre_study() was using the value of the re argument before
593        testing it for NULL. (Of course, in any sensible call of the function, it
594        won't be NULL.)
596     3. The memmove() emulation function in pcre_internal.h, which is used on
597        systems that lack both memmove() and bcopy() - that is, hardly ever -
598        was missing a "static" storage class specifier.
600     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
601        containing an extended class (one that cannot be represented by a bitmap
602        because it contains high-valued characters or Unicode property items, e.g.
603        [\pZ]). Almost always one would set UTF-8 mode when processing such a
604        pattern, but PCRE should not loop if you do not (it no longer does).
605        [Detail: two cases were found: (a) a repeated subpattern containing an
606        extended class; (b) a recursive reference to a subpattern that followed a
607        previous extended class. It wasn't skipping over the extended class
608        correctly when UTF-8 mode was not set.]
610     5. A negated single-character class was not being recognized as fixed-length
611        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
612        compile error "lookbehind assertion is not fixed length".
614     6. The RunPerlTest auxiliary script was showing an unexpected difference
615        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
616        write a Perl script that can interpret lines of an input file either as
617        byte characters or as UTF-8, which is what "perltest" was being required to
618        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
619        can't do is switch easily at run time between having the "use utf8;" pragma
620        or not. In the end, I fudged it by using the RunPerlTest script to insert
621        "use utf8;" explicitly for the UTF-8 tests.
623     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
624        the end of the subject string, contrary to the documentation and to what
625        Perl does. This was true of both matching functions. Now it matches only at
626        the start of the subject and immediately after *internal* newlines.
628     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
629        a pointer to an int instead of a pointer to an unsigned long int. This
630        caused problems on 64-bit systems.
632     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
633        instance of the 'standard' template library not being so standard".
635    10. There was no check on the number of named subpatterns nor the maximum
636        length of a subpattern name. The product of these values is used to compute
637        the size of the memory block for a compiled pattern. By supplying a very
638        long subpattern name and a large number of named subpatterns, the size
639        computation could be caused to overflow. This is now prevented by limiting
640        the length of names to 32 characters, and the number of named subpatterns
641        to 10,000.
643    11. Subpatterns that are repeated with specific counts have to be replicated in
644        the compiled pattern. The size of memory for this was computed from the
645        length of the subpattern and the repeat count. The latter is limited to
646        65535, but there was no limit on the former, meaning that integer overflow
647        could in principle occur. The compiled length of a repeated subpattern is
648        now limited to 30,000 bytes in order to prevent this.
650    12. Added the optional facility to have named substrings with the same name.
652    13. Added the ability to use a named substring as a condition, using the
653        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
654        are numbers (not recommended). Forward references are permitted.
656    14. Added forward references in named backreferences (if you see what I mean).
658    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
659        pattern could run off the end of the subject. For example, the pattern
660        "(?s)(.{1,5})"8 did this with the subject "ab".
662    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
663        PCRE_CASELESS was set when matching characters that were quantified with ?
664        or *.
666    17. A character class other than a single negated character that had a minimum
667        but no maximum quantifier - for example [ab]{6,} - was not handled
668        correctly by pce_dfa_exec(). It would match only one character.
670    18. A valid (though odd) pattern that looked like a POSIX character
671        class but used an invalid character after [ (for example [[,abc,]]) caused
672        pcre_compile() to give the error "Failed: internal error: code overflow" or
673        in some cases to crash with a glibc free() error. This could even happen if
674        the pattern terminated after [[ but there just happened to be a sequence of
675        letters, a binary zero, and a closing ] in the memory that followed.
677    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
678        over the years. Originally (before any Unicode support), just the bottom 8
679        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
680        output from "man perlunicode" includes this:
682          The regular expression compiler produces polymorphic opcodes.  That
683          is, the pattern adapts to the data and automatically switches to
684          the Unicode character scheme when presented with Unicode data--or
685          instead uses a traditional byte scheme when presented with byte
686          data.
688        Sadly, a wide octal escape does not cause a switch, and in a string with
689        no other multibyte characters, these octal escapes are treated as before.
690        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
691        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
692        Unicode string.
694        I have not perpetrated such confusion in PCRE. Up till now, it took just
695        the bottom 8 bits, as in old Perl. I have now made octal escapes with
696        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
697        translate to the appropriate multibyte character.
699    29. Applied some refactoring to reduce the number of warnings from Microsoft
700        and Borland compilers. This has included removing the fudge introduced
701        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
702        a warning about an unused variable.
704    21. PCRE has not included VT (character 0x0b) in the set of whitespace
705        characters since release 4.0, because Perl (from release 5.004) does not.
706        [Or at least, is documented not to: some releases seem to be in conflict
707        with the documentation.] However, when a pattern was studied with
708        pcre_study() and all its branches started with \s, PCRE still included VT
709        as a possible starting character. Of course, this did no harm; it just
710        caused an unnecessary match attempt.
712    22. Removed a now-redundant internal flag bit that recorded the fact that case
713        dependency changed within the pattern. This was once needed for "required
714        byte" processing, but is no longer used. This recovers a now-scarce options
715        bit. Also moved the least significant internal flag bit to the most-
716        significant bit of the word, which was not previously used (hangover from
717        the days when it was an int rather than a uint) to free up another bit for
718        the future.
720    23. Added support for CRLF line endings as well as CR and LF. As well as the
721        default being selectable at build time, it can now be changed at runtime
722        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
723        specify that it is scanning data with non-default line endings.
725    24. Changed the definition of CXXLINK to make it agree with the definition of
726        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
728    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
729        recursions. This makes a big different to stack usage for some patterns.
731    26. If a subpattern containing a named recursion or subroutine reference such
732        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
733        the space required for the compiled pattern went wrong and gave too small a
734        value. Depending on the environment, this could lead to "Failed: internal
735        error: code overflow at offset 49" or "glibc detected double free or
736        corruption" errors.
738    27. Applied patches from Google (a) to support the new newline modes and (b) to
739        advance over multibyte UTF-8 characters in GlobalReplace.
741    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
742        difference for some implementation of PCRE in some Windows version.
744    29. Added some extra testing facilities to pcretest:
746        \q<number>   in a data line sets the "match limit" value
747        \Q<number>   in a data line sets the "match recursion limt" value
748        -S <number>  sets the stack size, where <number> is in megabytes
750        The -S option isn't available for Windows.
753    Version 6.6 06-Feb-06
754    ---------------------
756     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
757        in pcreposix.h. I have copied the definition from pcre.h.
759     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
760        because pcre.h is no longer a built file.
762     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
763        not normally included in the compiled code.
766    Version 6.5 01-Feb-06
767    ---------------------
769     1. When using the partial match feature with pcre_dfa_exec(), it was not
770        anchoring the second and subsequent partial matches at the new starting
771        point. This could lead to incorrect results. For example, with the pattern
772        /1234/, partially matching against "123" and then "a4" gave a match.
774     2. Changes to pcregrep:
776        (a) All non-match returns from pcre_exec() were being treated as failures
777            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
778            error message is output. Some extra information is given for the
779            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
780            probably the only errors that are likely to be caused by users (by
781            specifying a regex that has nested indefinite repeats, for instance).
782            If there are more than 20 of these errors, pcregrep is abandoned.
784        (b) A binary zero was treated as data while matching, but terminated the
785            output line if it was written out. This has been fixed: binary zeroes
786            are now no different to any other data bytes.
788        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
789            used to set a locale for matching. The --locale=xxxx long option has
790            been added (no short equivalent) to specify a locale explicitly on the
791            pcregrep command, overriding the environment variables.
793        (d) When -B was used with -n, some line numbers in the output were one less
794            than they should have been.
796        (e) Added the -o (--only-matching) option.
798        (f) If -A or -C was used with -c (count only), some lines of context were
799            accidentally printed for the final match.
801        (g) Added the -H (--with-filename) option.
803        (h) The combination of options -rh failed to suppress file names for files
804            that were found from directory arguments.
806        (i) Added the -D (--devices) and -d (--directories) options.
808        (j) Added the -F (--fixed-strings) option.
810        (k) Allow "-" to be used as a file name for -f as well as for a data file.
812        (l) Added the --colo(u)r option.
814        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
815            is not present by default.
817     3. A nasty bug was discovered in the handling of recursive patterns, that is,
818        items such as (?R) or (?1), when the recursion could match a number of
819        alternatives. If it matched one of the alternatives, but subsequently,
820        outside the recursion, there was a failure, the code tried to back up into
821        the recursion. However, because of the way PCRE is implemented, this is not
822        possible, and the result was an incorrect result from the match.
824        In order to prevent this happening, the specification of recursion has
825        been changed so that all such subpatterns are automatically treated as
826        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
828     4. I had overlooked the fact that, in some locales, there are characters for
829        which isalpha() is true but neither isupper() nor islower() are true. In
830        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
831        and ordfeminine) are like this. This affected the treatment of \w and \W
832        when they appeared in character classes, but not when they appeared outside
833        a character class. The bit map for "word" characters is now created
834        separately from the results of isalnum() instead of just taking it from the
835        upper, lower, and digit maps. (Plus the underscore character, of course.)
837     5. The above bug also affected the handling of POSIX character classes such as
838        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
839        permanent tables. Instead, the bit maps for such a class were previously
840        created as the appropriate unions of the upper, lower, and digit bitmaps.
841        Now they are created by subtraction from the [[:word:]] class, which has
842        its own bitmap.
844     6. The [[:blank:]] character class matches horizontal, but not vertical space.
845        It is created by subtracting the vertical space characters (\x09, \x0a,
846        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
847        subtraction was done in the overall bitmap for a character class, meaning
848        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
849        be recognized. This bug has been fixed.
851     7. Patches from the folks at Google:
853          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
854          real life, but is still worth protecting against".
856          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
857          regular expressions".
859          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
860          have it.
862          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
863          "configure" and the latter not, in order to fix a problem somebody had
864          with compiling the Arg class on HP-UX.
866          (e) Improve the error-handling of the C++ wrapper a little bit.
868          (f) New tests for checking recursion limiting.
870     8. The pcre_memmove() function, which is used only if the environment does not
871        have a standard memmove() function (and is therefore rarely compiled),
872        contained two bugs: (a) use of int instead of size_t, and (b) it was not
873        returning a result (though PCRE never actually uses the result).
875     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
876        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
877        returned instead of calling malloc() with an overflowing number that would
878        most likely cause subsequent chaos.
880    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
882    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
883        with this option is matched, the nmatch and pmatch options of regexec() are
884        ignored.
886    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
887        provided in case anyone wants to the the POSIX interface with UTF-8
888        strings.
890    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
891        C++ linking (needed for some HP-UX environments).
893    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
894        (unused parameter) and in the pcre_printint() function (omitted "default"
895        switch label when the default is to do nothing).
897    15. Added some code to make it possible, when PCRE is compiled as a C++
898        library, to replace subject pointers for pcre_exec() with a smart pointer
899        class, thus making it possible to process discontinuous strings.
901    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
902        much the same function. They were added by different people who were trying
903        to make PCRE easy to compile on non-Unix systems. It has been suggested
904        that PCRE_EXPORT be abolished now that there is more automatic apparatus
905        for compiling on Windows systems. I have therefore replaced it with
906        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
907        defaults to "extern" for C or "extern C" for C++, which works fine on
908        Unix-like systems. It is now possible to override the value of PCRE_DATA_
909        SCOPE with something explicit in config.h. In addition:
911        (a) pcreposix.h still had just "extern" instead of either of these macros;
912            I have replaced it with PCRE_DATA_SCOPE.
914        (b) Functions such as _pcre_xclass(), which are internal to the library,
915            but external in the C sense, all had PCRE_EXPORT in their definitions.
916            This is apparently wrong for the Windows case, so I have removed it.
917            (It makes no difference on Unix-like systems.)
919    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
920        of recursive calls to match(). This is different to MATCH_LIMIT because
921        that limits the total number of calls to match(), not all of which increase
922        the depth of recursion. Limiting the recursion depth limits the amount of
923        stack (or heap if NO_RECURSE is set) that is used. The default can be set
924        when PCRE is compiled, and changed at run time. A patch from Google adds
925        this functionality to the C++ interface.
927    18. Changes to the handling of Unicode character properties:
929        (a) Updated the table to Unicode 4.1.0.
931        (b) Recognize characters that are not in the table as "Cn" (undefined).
933        (c) I revised the way the table is implemented to a much improved format
934            which includes recognition of ranges. It now supports the ranges that
935            are defined in UnicodeData.txt, and it also amalgamates other
936            characters into ranges. This has reduced the number of entries in the
937            table from around 16,000 to around 3,000, thus reducing its size
938            considerably. I realized I did not need to use a tree structure after
939            all - a binary chop search is just as efficient. Having reduced the
940            number of entries, I extended their size from 6 bytes to 8 bytes to
941            allow for more data.
943        (d) Added support for Unicode script names via properties such as \p{Han}.
945    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
946        matching that character.
948    20. When matching a repeated Unicode property with a minimum greater than zero,
949        (for example \pL{2,}), PCRE could look past the end of the subject if it
950        reached it while seeking the minimum number of characters. This could
951        happen only if some of the characters were more than one byte long, because
952        there is a check for at least the minimum number of bytes.
954    21. Refactored the implementation of \p and \P so as to be more general, to
955        allow for more different types of property in future. This has changed the
956        compiled form incompatibly. Anybody with saved compiled patterns that use
957        \p or \P will have to recompile them.
959    22. Added "Any" and "L&" to the supported property types.
961    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
962        but give a compile time error if the value is greater than 0xff.
964    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
965        accidentally not being installed or uninstalled.
967    25. The pcre.h file was built from pcre.h.in, but the only changes that were
968        made were to insert the current release number. This seemed silly, because
969        it made things harder for people building PCRE on systems that don't run
970        "configure". I have turned pcre.h into a distributed file, no longer built
971        by "configure", with the version identification directly included. There is
972        no longer a pcre.h.in file.
974        However, this change necessitated a change to the pcre-config script as
975        well. It is built from pcre-config.in, and one of the substitutions was the
976        release number. I have updated configure.ac so that ./configure now finds
977        the release number by grepping pcre.h.
979    26. Added the ability to run the tests under valgrind.
982    Version 6.4 05-Sep-05
983    ---------------------
985     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
986        "--" to be printed when multiple files were scanned, even when none of the
987        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
988        consider it to be a bug, and have restored the previous behaviour.
990     2. A couple of code tidies to get rid of compiler warnings.
992     3. The pcretest program used to cheat by referring to symbols in the library
993        whose names begin with _pcre_. These are internal symbols that are not
994        really supposed to be visible externally, and in some environments it is
995        possible to suppress them. The cheating is now confined to including
996        certain files from the library's source, which is a bit cleaner.
998     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
999        file's purpose clearer.
1001     5. Reorganized pcre_ucp_findchar().
1004  Version 6.3 15-Aug-05  Version 6.3 15-Aug-05
1005  ---------------------  ---------------------

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