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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.2 05-June-07
5    ---------------------
7     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
8        which is apparently normally available under Windows.
10     2. Re-jig the pcregrep tests with different newline settings in an attempt
11        to make them independent of the local environment's newline setting.
13     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
15     4. Some of the "internals" tests were previously cut out when the link size
16        was not 2, because the output contained actual offsets. The recent new
17        "Z" feature of pcretest means that these can be cut out, making the tests
18        usable with all link sizes.
20     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
21        stack recursion. This gives a massive performance boost under BSD, but just
22        a small improvement under Linux. However, it saves one field in the frame
23        in all cases.
25     6. Added more features from the forthcoming Perl 5.10:
27        (a) (?-n) (where n is a string of digits) is a relative subroutine or
28            recursion call. It refers to the nth most recently opened parentheses.
30        (b) (?+n) is also a relative subroutine call; it refers to the nth next
31            to be opened parentheses.
33        (c) Conditions that refer to capturing parentheses can be specified
34            relatively, for example, (?(-2)... or (?(+3)...
36        (d) \K resets the start of the current match so that everything before
37            is not part of it.
39        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
41        (f) \g{name} is another synonym - part of Perl 5.10's unification of
42            reference syntax.
44        (g) (?| introduces a group in which the numbering of parentheses in each
45            alternative starts with the same number.
47     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
50     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
51        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
52        for detecting groups that can match an empty string.
54     9. A pattern with a very large number of alternatives (more than several
55        hundred) was running out of internal workspace during the pre-compile
56        phase, where pcre_compile() figures out how much memory will be needed. A
57        bit of new cunning has reduced the workspace needed for groups with
58        alternatives. The 1000-alternative test pattern now uses 12 bytes of
59        workspace instead of running out of the 4096 that are available.
62    Version 7.1 24-Apr-07
63    ---------------------
65     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
66        that is more "standard", making use of automake and other Autotools. There
67        is some re-arrangement of the files and adjustment of comments consequent
68        on this.
70     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
71        for recursive directory scanning broke on some systems because the files
72        are not scanned in any specific order and on different systems the order
73        was different. A call to "sort" has been inserted into RunGrepTest for the
74        approprate test as a short-term fix. In the longer term there may be an
75        alternative.
77     3. I had an email from Eric Raymond about problems translating some of PCRE's
78        man pages to HTML (despite the fact that I distribute HTML pages, some
79        people do their own conversions for various reasons). The problems
80        concerned the use of low-level troff macros .br and .in. I have therefore
81        removed all such uses from the man pages (some were redundant, some could
82        be replaced by .nf/.fi pairs). The 132html script that I use to generate
83        HTML has been updated to handle .nf/.fi and to complain if it encounters
84        .br or .in.
86     4. Updated comments in configure.ac that get placed in config.h.in and also
87        arranged for config.h to be included in the distribution, with the name
88        config.h.generic, for the benefit of those who have to compile without
89        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
91     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
92        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
93        makevp.bat for the current PCRE, using the additional files
94        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
96     6. A Windows user reported a minor discrepancy with test 2, which turned out
97        to be caused by a trailing space on an input line that had got lost in his
98        copy. The trailing space was an accident, so I've just removed it.
100     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
101        that is needed.
103     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
104        as "const" (a) because they are and (b) because it helps the PHP
105        maintainers who have recently made a script to detect big data structures
106        in the php code that should be moved to the .rodata section. I remembered
107        to update Builducptable as well, so it won't revert if ucptable.h is ever
108        re-created.
110     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
111        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
112        order to be able to cut out the UTF-8 tables in the latter when UTF-8
113        support is not required. This saves 1.5-2K of code, which is important in
114        some applications.
116        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
117        so as not to refer to the tables, even though these functions will never be
118        called when UTF-8 support is disabled. Otherwise there are problems with a
119        shared library.
121    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
123        (a) It was defining its arguments as char * instead of void *.
125        (b) It was assuming that all moves were upwards in memory; this was true
126            a long time ago when I wrote it, but is no longer the case.
128        The emulated memove() is provided for those environments that have neither
129        memmove() nor bcopy(). I didn't think anyone used it these days, but that
130        is clearly not the case, as these two bugs were recently reported.
132    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
133        and Detrail to create the HTML documentation, the .txt form of the man
134        pages, and it removes trailing spaces from listed files. It also creates
135        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
136        case, it wraps all the #defines with #ifndefs. This script should be run
137        before "make dist".
139    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
140        with Unicode property support.
142        (a) For a maximizing quantifier, if the two different cases of the
143            character were of different lengths in their UTF-8 codings (there are
144            some cases like this - I found 11), and the matching function had to
145            back up over a mixture of the two cases, it incorrectly assumed they
146            were both the same length.
148        (b) When PCRE was configured to use the heap rather than the stack for
149            recursion during matching, it was not correctly preserving the data for
150            the other case of a UTF-8 character when checking ahead for a match
151            while processing a minimizing repeat. If the check also involved
152            matching a wide character, but failed, corruption could cause an
153            erroneous result when trying to check for a repeat of the original
154            character.
156    13. Some tidying changes to the testing mechanism:
158        (a) The RunTest script now detects the internal link size and whether there
159            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
160            values substituted by "configure". (The RunGrepTest script already did
161            this for UTF-8.) The configure.ac script no longer substitutes the
162            relevant variables.
164        (b) The debugging options /B and /D in pcretest show the compiled bytecode
165            with length and offset values. This means that the output is different
166            for different internal link sizes. Test 2 is skipped for link sizes
167            other than 2 because of this, bypassing the problem. Unfortunately,
168            there was also a test in test 3 (the locale tests) that used /B and
169            failed for link sizes other than 2. Rather than cut the whole test out,
170            I have added a new /Z option to pcretest that replaces the length and
171            offset values with spaces. This is now used to make test 3 independent
172            of link size. (Test 2 will be tidied up later.)
174    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
175        segmentation fault instead of returning the appropriate error message.
177    15. In multiline mode when the newline sequence was set to "any", the pattern
178        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
179        This doesn't seem right; it now treats the CRLF combination as the line
180        ending, and so does not match in that case. It's only a pattern such as ^$
181        that would hit this one: something like ^ABC$ would have failed after \r
182        and then tried again after \r\n.
184    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
185        in an attempt to make files that differ only in their line terminators
186        compare equal. This works on Linux.
188    17. Under certain error circumstances pcregrep might try to free random memory
189        as it exited. This is now fixed, thanks to valgrind.
191    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
192        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
193        was because its rules for how to advance for /g after matching an empty
194        string at the end of a line did not allow for this case. They now check for
195        it specially.
197    20. pcretest is supposed to handle patterns and data of any length, by
198        extending its buffers when necessary. It was getting this wrong when the
199        buffer for a data line had to be extended.
201    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
202        CRLF as a newline sequence.
204    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
205        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
206        I have nevertheless tidied it up.
208    23. Added some casts to kill warnings from HP-UX ia64 compiler.
210    24. Added a man page for pcre-config.
213    Version 7.0 19-Dec-06
214    ---------------------
216     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
217        moving to gcc 4.1.1.
219     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
220        sys/time.h, which is documented as needed for this function. It doesn't
221        seem to matter on Linux, but it showed up on some releases of OS X.
223     3. It seems that there are systems where bytes whose values are greater than
224        127 match isprint() in the "C" locale. The "C" locale should be the
225        default when a C program starts up. In most systems, only ASCII printing
226        characters match isprint(). This difference caused the output from pcretest
227        to vary, making some of the tests fail. I have changed pcretest so that:
229        (a) When it is outputting text in the compiled version of a pattern, bytes
230            other than 32-126 are always shown as hex escapes.
232        (b) When it is outputting text that is a matched part of a subject string,
233            it does the same, unless a different locale has been set for the match
234            (using the /L modifier). In this case, it uses isprint() to decide.
236     4. Fixed a major bug that caused incorrect computation of the amount of memory
237        required for a compiled pattern when options that changed within the
238        pattern affected the logic of the preliminary scan that determines the
239        length. The relevant options are -x, and -i in UTF-8 mode. The result was
240        that the computed length was too small. The symptoms of this bug were
241        either the PCRE error "internal error: code overflow" from pcre_compile(),
242        or a glibc crash with a message such as "pcretest: free(): invalid next
243        size (fast)". Examples of patterns that provoked this bug (shown in
244        pcretest format) are:
246          /(?-x: )/x
247          /(?x)(?-x: \s*#\s*)/
248          /((?i)[\x{c0}])/8
249          /(?i:[\x{c0}])/8
251        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
252        is now done differently.
254     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
255        wrapper classes; (b) implement a new function in the C++ scanner that is
256        more efficient than the old way of doing things because it avoids levels of
257        recursion in the regex matching; (c) add a paragraph to the documentation
258        for the FullMatch() function.
260     6. The escape sequence \n was being treated as whatever was defined as
261        "newline". Not only was this contrary to the documentation, which states
262        that \n is character 10 (hex 0A), but it also went horribly wrong when
263        "newline" was defined as CRLF. This has been fixed.
265     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
266        was being set to -1 for the "end of line" case (supposedly a value that no
267        character can have). Though this value is never used (the check for end of
268        line is "zero bytes in current character"), it caused compiler complaints.
269        I've changed it to 0xffffffff.
271     8. In pcre_version.c, the version string was being built by a sequence of
272        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
273        string (as it is for production releases) called a macro with an empty
274        argument. The C standard says the result of this is undefined. The gcc
275        compiler treats it as an empty string (which was what was wanted) but it is
276        reported that Visual C gives an error. The source has been hacked around to
277        avoid this problem.
279     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
280        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
281        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
282        of them did).
284    10. Originally, pcretest opened its input and output without "b"; then I was
285        told that "b" was needed in some environments, so it was added for release
286        5.0 to both the input and output. (It makes no difference on Unix-like
287        systems.) Later I was told that it is wrong for the input on Windows. I've
288        now abstracted the modes into two macros, to make it easier to fiddle with
289        them, and removed "b" from the input mode under Windows.
291    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
293    12. Added -help and --help to pcretest as an official way of being reminded
294        of the options.
296    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
297        and pcrecpp.cc because they annoy compilers at high warning levels.
299    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
301    15. Fixed an occurrence of == in configure.ac that should have been = (shell
302        scripts are not C programs :-) and which was not noticed because it works
303        on Linux.
305    16. pcretest is supposed to handle any length of pattern and data line (as one
306        line or as a continued sequence of lines) by extending its input buffer if
307        necessary. This feature was broken for very long pattern lines, leading to
308        a string of junk being passed to pcre_compile() if the pattern was longer
309        than about 50K.
311    17. I have done a major re-factoring of the way pcre_compile() computes the
312        amount of memory needed for a compiled pattern. Previously, there was code
313        that made a preliminary scan of the pattern in order to do this. That was
314        OK when PCRE was new, but as the facilities have expanded, it has become
315        harder and harder to keep it in step with the real compile phase, and there
316        have been a number of bugs (see for example, 4 above). I have now found a
317        cunning way of running the real compile function in a "fake" mode that
318        enables it to compute how much memory it would need, while actually only
319        ever using a few hundred bytes of working memory and without too many
320        tests of the mode. This should make future maintenance and development
321        easier. A side effect of this work is that the limit of 200 on the nesting
322        depth of parentheses has been removed (though this was never a serious
323        limitation, I suspect). However, there is a downside: pcre_compile() now
324        runs more slowly than before (30% or more, depending on the pattern). I
325        hope this isn't a big issue. There is no effect on runtime performance.
327    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
328        newline (only possible for the last line of a file) and it was a
329        pattern that set a locale (followed by /Lsomething), pcretest crashed.
331    19. Added additional timing features to pcretest. (1) The -tm option now times
332        matching only, not compiling. (2) Both -t and -tm can be followed, as a
333        separate command line item, by a number that specifies the number of
334        repeats to use when timing. The default is 50000; this gives better
335        precision, but takes uncomfortably long for very large patterns.
337    20. Extended pcre_study() to be more clever in cases where a branch of a
338        subpattern has no definite first character. For example, (a*|b*)[cd] would
339        previously give no result from pcre_study(). Now it recognizes that the
340        first character must be a, b, c, or d.
342    21. There was an incorrect error "recursive call could loop indefinitely" if
343        a subpattern (or the entire pattern) that was being tested for matching an
344        empty string contained only one non-empty item after a nested subpattern.
345        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
346        incorrectly, because the \d was being skipped in the check.
348    22. The pcretest program now has a new pattern option /B and a command line
349        option -b, which is equivalent to adding /B to every pattern. This causes
350        it to show the compiled bytecode, without the additional information that
351        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
352        is the same as /B/I).
354    23. A new optimization is now able automatically to treat some sequences such
355        as a*b as a*+b. More specifically, if something simple (such as a character
356        or a simple class like \d) has an unlimited quantifier, and is followed by
357        something that cannot possibly match the quantified thing, the quantifier
358        is automatically "possessified".
360    24. A recursive reference to a subpattern whose number was greater than 39
361        went wrong under certain circumstances in UTF-8 mode. This bug could also
362        have affected the operation of pcre_study().
364    25. Realized that a little bit of performance could be had by replacing
365        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
367    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
369    27. Possessive quantifiers such as a++ were previously implemented by turning
370        them into atomic groups such as ($>a+). Now they have their own opcodes,
371        which improves performance. This includes the automatically created ones
372        from 23 above.
374    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
375        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
376        the first matched character to be a colon. This applied both to named and
377        numbered groups.
379    29. The ucpinternal.h header file was missing its idempotency #ifdef.
381    30. I was sent a "project" file called libpcre.a.dev which I understand makes
382        building PCRE on Windows easier, so I have included it in the distribution.
384    31. There is now a check in pcretest against a ridiculously large number being
385        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
386        loop, the loop is abandoned.
388    32. Forward references to subpatterns in conditions such as (?(2)...) where
389        subpattern 2 is defined later cause pcre_compile() to search forwards in
390        the pattern for the relevant set of parentheses. This search went wrong
391        when there were unescaped parentheses in a character class, parentheses
392        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
394    33. "Subroutine" calls and backreferences were previously restricted to
395        referencing subpatterns earlier in the regex. This restriction has now
396        been removed.
398    34. Added a number of extra features that are going to be in Perl 5.10. On the
399        whole, these are just syntactic alternatives for features that PCRE had
400        previously implemented using the Python syntax or my own invention. The
401        other formats are all retained for compatibility.
403        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
404            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
405            also .NET compatible.
407        (b) A recursion or subroutine call to a named group can now be defined as
408            (?&name) as well as (?P>name).
410        (c) A backreference to a named group can now be defined as \k<name> or
411            \k'name' as well as (?P=name). The new forms, as well as being in Perl
412            5.10, are also .NET compatible.
414        (d) A conditional reference to a named group can now use the syntax
415            (?(<name>) or (?('name') as well as (?(name).
417        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
418            groups (named and numbered) that are never evaluated inline, but can be
419            called as "subroutines" from elsewhere. In effect, the DEFINE condition
420            is always false. There may be only one alternative in such a group.
422        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
423            as the simple (?(R). The condition is true only if the most recent
424            recursion is that of the given number or name. It does not search out
425            through the entire recursion stack.
427        (g) The escape \gN or \g{N} has been added, where N is a positive or
428            negative number, specifying an absolute or relative reference.
430    35. Tidied to get rid of some further signed/unsigned compiler warnings and
431        some "unreachable code" warnings.
433    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
434        things, this adds five new scripts.
436    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
437        There were also incompatibilities regarding the handling of \Q..\E inside
438        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
439        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
441    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
442        matches an empty string, and forcibly breaks the loop. There were bugs in
443        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
444        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
445        separate and independent bugs (that affected different cases) have been
446        fixed.
448    39. Refactored the code to abolish the use of different opcodes for small
449        capturing bracket numbers. This is a tidy that I avoided doing when I
450        removed the limit on the number of capturing brackets for 3.5 back in 2001.
451        The new approach is not only tidier, it makes it possible to reduce the
452        memory needed to fix the previous bug (38).
454    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
455        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
456        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
457        mode.
459    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
460        report.
462    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
463        copy construction and assignment in the C++ wrapper.
465    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
466        couple of bugs that could have given wrong results in the "--newline=crlf"
467        case.
469    44. Added a number of casts and did some reorganization of signed/unsigned int
470        variables following suggestions from Dair Grant. Also renamed the variable
471        "this" as "item" because it is a C++ keyword.
473    45. Arranged for dftables to add
475          #include "pcre_internal.h"
477        to pcre_chartables.c because without it, gcc 4.x may remove the array
478        definition from the final binary if PCRE is built into a static library and
479        dead code stripping is activated.
481    46. For an unanchored pattern, if a match attempt fails at the start of a
482        newline sequence, and the newline setting is CRLF or ANY, and the next two
483        characters are CRLF, advance by two characters instead of one.
486    Version 6.7 04-Jul-06
487    ---------------------
489     1. In order to handle tests when input lines are enormously long, pcretest has
490        been re-factored so that it automatically extends its buffers when
491        necessary. The code is crude, but this _is_ just a test program. The
492        default size has been increased from 32K to 50K.
494     2. The code in pcre_study() was using the value of the re argument before
495        testing it for NULL. (Of course, in any sensible call of the function, it
496        won't be NULL.)
498     3. The memmove() emulation function in pcre_internal.h, which is used on
499        systems that lack both memmove() and bcopy() - that is, hardly ever -
500        was missing a "static" storage class specifier.
502     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
503        containing an extended class (one that cannot be represented by a bitmap
504        because it contains high-valued characters or Unicode property items, e.g.
505        [\pZ]). Almost always one would set UTF-8 mode when processing such a
506        pattern, but PCRE should not loop if you do not (it no longer does).
507        [Detail: two cases were found: (a) a repeated subpattern containing an
508        extended class; (b) a recursive reference to a subpattern that followed a
509        previous extended class. It wasn't skipping over the extended class
510        correctly when UTF-8 mode was not set.]
512     5. A negated single-character class was not being recognized as fixed-length
513        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
514        compile error "lookbehind assertion is not fixed length".
516     6. The RunPerlTest auxiliary script was showing an unexpected difference
517        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
518        write a Perl script that can interpret lines of an input file either as
519        byte characters or as UTF-8, which is what "perltest" was being required to
520        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
521        can't do is switch easily at run time between having the "use utf8;" pragma
522        or not. In the end, I fudged it by using the RunPerlTest script to insert
523        "use utf8;" explicitly for the UTF-8 tests.
525     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
526        the end of the subject string, contrary to the documentation and to what
527        Perl does. This was true of both matching functions. Now it matches only at
528        the start of the subject and immediately after *internal* newlines.
530     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
531        a pointer to an int instead of a pointer to an unsigned long int. This
532        caused problems on 64-bit systems.
534     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
535        instance of the 'standard' template library not being so standard".
537    10. There was no check on the number of named subpatterns nor the maximum
538        length of a subpattern name. The product of these values is used to compute
539        the size of the memory block for a compiled pattern. By supplying a very
540        long subpattern name and a large number of named subpatterns, the size
541        computation could be caused to overflow. This is now prevented by limiting
542        the length of names to 32 characters, and the number of named subpatterns
543        to 10,000.
545    11. Subpatterns that are repeated with specific counts have to be replicated in
546        the compiled pattern. The size of memory for this was computed from the
547        length of the subpattern and the repeat count. The latter is limited to
548        65535, but there was no limit on the former, meaning that integer overflow
549        could in principle occur. The compiled length of a repeated subpattern is
550        now limited to 30,000 bytes in order to prevent this.
552    12. Added the optional facility to have named substrings with the same name.
554    13. Added the ability to use a named substring as a condition, using the
555        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
556        are numbers (not recommended). Forward references are permitted.
558    14. Added forward references in named backreferences (if you see what I mean).
560    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
561        pattern could run off the end of the subject. For example, the pattern
562        "(?s)(.{1,5})"8 did this with the subject "ab".
564    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
565        PCRE_CASELESS was set when matching characters that were quantified with ?
566        or *.
568    17. A character class other than a single negated character that had a minimum
569        but no maximum quantifier - for example [ab]{6,} - was not handled
570        correctly by pce_dfa_exec(). It would match only one character.
572    18. A valid (though odd) pattern that looked like a POSIX character
573        class but used an invalid character after [ (for example [[,abc,]]) caused
574        pcre_compile() to give the error "Failed: internal error: code overflow" or
575        in some cases to crash with a glibc free() error. This could even happen if
576        the pattern terminated after [[ but there just happened to be a sequence of
577        letters, a binary zero, and a closing ] in the memory that followed.
579    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
580        over the years. Originally (before any Unicode support), just the bottom 8
581        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
582        output from "man perlunicode" includes this:
584          The regular expression compiler produces polymorphic opcodes.  That
585          is, the pattern adapts to the data and automatically switches to
586          the Unicode character scheme when presented with Unicode data--or
587          instead uses a traditional byte scheme when presented with byte
588          data.
590        Sadly, a wide octal escape does not cause a switch, and in a string with
591        no other multibyte characters, these octal escapes are treated as before.
592        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
593        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
594        Unicode string.
596        I have not perpetrated such confusion in PCRE. Up till now, it took just
597        the bottom 8 bits, as in old Perl. I have now made octal escapes with
598        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
599        translate to the appropriate multibyte character.
601    29. Applied some refactoring to reduce the number of warnings from Microsoft
602        and Borland compilers. This has included removing the fudge introduced
603        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
604        a warning about an unused variable.
606    21. PCRE has not included VT (character 0x0b) in the set of whitespace
607        characters since release 4.0, because Perl (from release 5.004) does not.
608        [Or at least, is documented not to: some releases seem to be in conflict
609        with the documentation.] However, when a pattern was studied with
610        pcre_study() and all its branches started with \s, PCRE still included VT
611        as a possible starting character. Of course, this did no harm; it just
612        caused an unnecessary match attempt.
614    22. Removed a now-redundant internal flag bit that recorded the fact that case
615        dependency changed within the pattern. This was once needed for "required
616        byte" processing, but is no longer used. This recovers a now-scarce options
617        bit. Also moved the least significant internal flag bit to the most-
618        significant bit of the word, which was not previously used (hangover from
619        the days when it was an int rather than a uint) to free up another bit for
620        the future.
622    23. Added support for CRLF line endings as well as CR and LF. As well as the
623        default being selectable at build time, it can now be changed at runtime
624        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
625        specify that it is scanning data with non-default line endings.
627    24. Changed the definition of CXXLINK to make it agree with the definition of
628        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
630    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
631        recursions. This makes a big different to stack usage for some patterns.
633    26. If a subpattern containing a named recursion or subroutine reference such
634        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
635        the space required for the compiled pattern went wrong and gave too small a
636        value. Depending on the environment, this could lead to "Failed: internal
637        error: code overflow at offset 49" or "glibc detected double free or
638        corruption" errors.
640    27. Applied patches from Google (a) to support the new newline modes and (b) to
641        advance over multibyte UTF-8 characters in GlobalReplace.
643    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
644        difference for some implementation of PCRE in some Windows version.
646    29. Added some extra testing facilities to pcretest:
648        \q<number>   in a data line sets the "match limit" value
649        \Q<number>   in a data line sets the "match recursion limt" value
650        -S <number>  sets the stack size, where <number> is in megabytes
652        The -S option isn't available for Windows.
655    Version 6.6 06-Feb-06
656    ---------------------
658     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
659        in pcreposix.h. I have copied the definition from pcre.h.
661     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
662        because pcre.h is no longer a built file.
664     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
665        not normally included in the compiled code.
668    Version 6.5 01-Feb-06
669    ---------------------
671     1. When using the partial match feature with pcre_dfa_exec(), it was not
672        anchoring the second and subsequent partial matches at the new starting
673        point. This could lead to incorrect results. For example, with the pattern
674        /1234/, partially matching against "123" and then "a4" gave a match.
676     2. Changes to pcregrep:
678        (a) All non-match returns from pcre_exec() were being treated as failures
679            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
680            error message is output. Some extra information is given for the
681            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
682            probably the only errors that are likely to be caused by users (by
683            specifying a regex that has nested indefinite repeats, for instance).
684            If there are more than 20 of these errors, pcregrep is abandoned.
686        (b) A binary zero was treated as data while matching, but terminated the
687            output line if it was written out. This has been fixed: binary zeroes
688            are now no different to any other data bytes.
690        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
691            used to set a locale for matching. The --locale=xxxx long option has
692            been added (no short equivalent) to specify a locale explicitly on the
693            pcregrep command, overriding the environment variables.
695        (d) When -B was used with -n, some line numbers in the output were one less
696            than they should have been.
698        (e) Added the -o (--only-matching) option.
700        (f) If -A or -C was used with -c (count only), some lines of context were
701            accidentally printed for the final match.
703        (g) Added the -H (--with-filename) option.
705        (h) The combination of options -rh failed to suppress file names for files
706            that were found from directory arguments.
708        (i) Added the -D (--devices) and -d (--directories) options.
710        (j) Added the -F (--fixed-strings) option.
712        (k) Allow "-" to be used as a file name for -f as well as for a data file.
714        (l) Added the --colo(u)r option.
716        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
717            is not present by default.
719     3. A nasty bug was discovered in the handling of recursive patterns, that is,
720        items such as (?R) or (?1), when the recursion could match a number of
721        alternatives. If it matched one of the alternatives, but subsequently,
722        outside the recursion, there was a failure, the code tried to back up into
723        the recursion. However, because of the way PCRE is implemented, this is not
724        possible, and the result was an incorrect result from the match.
726        In order to prevent this happening, the specification of recursion has
727        been changed so that all such subpatterns are automatically treated as
728        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
730     4. I had overlooked the fact that, in some locales, there are characters for
731        which isalpha() is true but neither isupper() nor islower() are true. In
732        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
733        and ordfeminine) are like this. This affected the treatment of \w and \W
734        when they appeared in character classes, but not when they appeared outside
735        a character class. The bit map for "word" characters is now created
736        separately from the results of isalnum() instead of just taking it from the
737        upper, lower, and digit maps. (Plus the underscore character, of course.)
739     5. The above bug also affected the handling of POSIX character classes such as
740        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
741        permanent tables. Instead, the bit maps for such a class were previously
742        created as the appropriate unions of the upper, lower, and digit bitmaps.
743        Now they are created by subtraction from the [[:word:]] class, which has
744        its own bitmap.
746     6. The [[:blank:]] character class matches horizontal, but not vertical space.
747        It is created by subtracting the vertical space characters (\x09, \x0a,
748        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
749        subtraction was done in the overall bitmap for a character class, meaning
750        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
751        be recognized. This bug has been fixed.
753     7. Patches from the folks at Google:
755          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
756          real life, but is still worth protecting against".
758          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
759          regular expressions".
761          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
762          have it.
764          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
765          "configure" and the latter not, in order to fix a problem somebody had
766          with compiling the Arg class on HP-UX.
768          (e) Improve the error-handling of the C++ wrapper a little bit.
770          (f) New tests for checking recursion limiting.
772     8. The pcre_memmove() function, which is used only if the environment does not
773        have a standard memmove() function (and is therefore rarely compiled),
774        contained two bugs: (a) use of int instead of size_t, and (b) it was not
775        returning a result (though PCRE never actually uses the result).
777     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
778        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
779        returned instead of calling malloc() with an overflowing number that would
780        most likely cause subsequent chaos.
782    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
784    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
785        with this option is matched, the nmatch and pmatch options of regexec() are
786        ignored.
788    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
789        provided in case anyone wants to the the POSIX interface with UTF-8
790        strings.
792    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
793        C++ linking (needed for some HP-UX environments).
795    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
796        (unused parameter) and in the pcre_printint() function (omitted "default"
797        switch label when the default is to do nothing).
799    15. Added some code to make it possible, when PCRE is compiled as a C++
800        library, to replace subject pointers for pcre_exec() with a smart pointer
801        class, thus making it possible to process discontinuous strings.
803    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
804        much the same function. They were added by different people who were trying
805        to make PCRE easy to compile on non-Unix systems. It has been suggested
806        that PCRE_EXPORT be abolished now that there is more automatic apparatus
807        for compiling on Windows systems. I have therefore replaced it with
808        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
809        defaults to "extern" for C or "extern C" for C++, which works fine on
810        Unix-like systems. It is now possible to override the value of PCRE_DATA_
811        SCOPE with something explicit in config.h. In addition:
813        (a) pcreposix.h still had just "extern" instead of either of these macros;
814            I have replaced it with PCRE_DATA_SCOPE.
816        (b) Functions such as _pcre_xclass(), which are internal to the library,
817            but external in the C sense, all had PCRE_EXPORT in their definitions.
818            This is apparently wrong for the Windows case, so I have removed it.
819            (It makes no difference on Unix-like systems.)
821    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
822        of recursive calls to match(). This is different to MATCH_LIMIT because
823        that limits the total number of calls to match(), not all of which increase
824        the depth of recursion. Limiting the recursion depth limits the amount of
825        stack (or heap if NO_RECURSE is set) that is used. The default can be set
826        when PCRE is compiled, and changed at run time. A patch from Google adds
827        this functionality to the C++ interface.
829    18. Changes to the handling of Unicode character properties:
831        (a) Updated the table to Unicode 4.1.0.
833        (b) Recognize characters that are not in the table as "Cn" (undefined).
835        (c) I revised the way the table is implemented to a much improved format
836            which includes recognition of ranges. It now supports the ranges that
837            are defined in UnicodeData.txt, and it also amalgamates other
838            characters into ranges. This has reduced the number of entries in the
839            table from around 16,000 to around 3,000, thus reducing its size
840            considerably. I realized I did not need to use a tree structure after
841            all - a binary chop search is just as efficient. Having reduced the
842            number of entries, I extended their size from 6 bytes to 8 bytes to
843            allow for more data.
845        (d) Added support for Unicode script names via properties such as \p{Han}.
847    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
848        matching that character.
850    20. When matching a repeated Unicode property with a minimum greater than zero,
851        (for example \pL{2,}), PCRE could look past the end of the subject if it
852        reached it while seeking the minimum number of characters. This could
853        happen only if some of the characters were more than one byte long, because
854        there is a check for at least the minimum number of bytes.
856    21. Refactored the implementation of \p and \P so as to be more general, to
857        allow for more different types of property in future. This has changed the
858        compiled form incompatibly. Anybody with saved compiled patterns that use
859        \p or \P will have to recompile them.
861    22. Added "Any" and "L&" to the supported property types.
863    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
864        but give a compile time error if the value is greater than 0xff.
866    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
867        accidentally not being installed or uninstalled.
869    25. The pcre.h file was built from pcre.h.in, but the only changes that were
870        made were to insert the current release number. This seemed silly, because
871        it made things harder for people building PCRE on systems that don't run
872        "configure". I have turned pcre.h into a distributed file, no longer built
873        by "configure", with the version identification directly included. There is
874        no longer a pcre.h.in file.
876        However, this change necessitated a change to the pcre-config script as
877        well. It is built from pcre-config.in, and one of the substitutions was the
878        release number. I have updated configure.ac so that ./configure now finds
879        the release number by grepping pcre.h.
881    26. Added the ability to run the tests under valgrind.
884    Version 6.4 05-Sep-05
885    ---------------------
887     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
888        "--" to be printed when multiple files were scanned, even when none of the
889        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
890        consider it to be a bug, and have restored the previous behaviour.
892     2. A couple of code tidies to get rid of compiler warnings.
894     3. The pcretest program used to cheat by referring to symbols in the library
895        whose names begin with _pcre_. These are internal symbols that are not
896        really supposed to be visible externally, and in some environments it is
897        possible to suppress them. The cheating is now confined to including
898        certain files from the library's source, which is a bit cleaner.
900     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
901        file's purpose clearer.
903     5. Reorganized pcre_ucp_findchar().
906  Version 6.3 15-Aug-05  Version 6.3 15-Aug-05
907  ---------------------  ---------------------

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