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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.2 01-May-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.
34    Version 7.1 24-Apr-07
35    ---------------------
37     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
38        that is more "standard", making use of automake and other Autotools. There
39        is some re-arrangement of the files and adjustment of comments consequent
40        on this.
42     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
43        for recursive directory scanning broke on some systems because the files
44        are not scanned in any specific order and on different systems the order
45        was different. A call to "sort" has been inserted into RunGrepTest for the
46        approprate test as a short-term fix. In the longer term there may be an
47        alternative.
49     3. I had an email from Eric Raymond about problems translating some of PCRE's
50        man pages to HTML (despite the fact that I distribute HTML pages, some
51        people do their own conversions for various reasons). The problems
52        concerned the use of low-level troff macros .br and .in. I have therefore
53        removed all such uses from the man pages (some were redundant, some could
54        be replaced by .nf/.fi pairs). The 132html script that I use to generate
55        HTML has been updated to handle .nf/.fi and to complain if it encounters
56        .br or .in.
58     4. Updated comments in configure.ac that get placed in config.h.in and also
59        arranged for config.h to be included in the distribution, with the name
60        config.h.generic, for the benefit of those who have to compile without
61        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
63     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
64        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
65        makevp.bat for the current PCRE, using the additional files
66        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
68     6. A Windows user reported a minor discrepancy with test 2, which turned out
69        to be caused by a trailing space on an input line that had got lost in his
70        copy. The trailing space was an accident, so I've just removed it.
72     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
73        that is needed.
75     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
76        as "const" (a) because they are and (b) because it helps the PHP
77        maintainers who have recently made a script to detect big data structures
78        in the php code that should be moved to the .rodata section. I remembered
79        to update Builducptable as well, so it won't revert if ucptable.h is ever
80        re-created.
82     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
83        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
84        order to be able to cut out the UTF-8 tables in the latter when UTF-8
85        support is not required. This saves 1.5-2K of code, which is important in
86        some applications.
88        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
89        so as not to refer to the tables, even though these functions will never be
90        called when UTF-8 support is disabled. Otherwise there are problems with a
91        shared library.
93    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
95        (a) It was defining its arguments as char * instead of void *.
97        (b) It was assuming that all moves were upwards in memory; this was true
98            a long time ago when I wrote it, but is no longer the case.
100        The emulated memove() is provided for those environments that have neither
101        memmove() nor bcopy(). I didn't think anyone used it these days, but that
102        is clearly not the case, as these two bugs were recently reported.
104    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
105        and Detrail to create the HTML documentation, the .txt form of the man
106        pages, and it removes trailing spaces from listed files. It also creates
107        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
108        case, it wraps all the #defines with #ifndefs. This script should be run
109        before "make dist".
111    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
112        with Unicode property support.
114        (a) For a maximizing quantifier, if the two different cases of the
115            character were of different lengths in their UTF-8 codings (there are
116            some cases like this - I found 11), and the matching function had to
117            back up over a mixture of the two cases, it incorrectly assumed they
118            were both the same length.
120        (b) When PCRE was configured to use the heap rather than the stack for
121            recursion during matching, it was not correctly preserving the data for
122            the other case of a UTF-8 character when checking ahead for a match
123            while processing a minimizing repeat. If the check also involved
124            matching a wide character, but failed, corruption could cause an
125            erroneous result when trying to check for a repeat of the original
126            character.
128    13. Some tidying changes to the testing mechanism:
130        (a) The RunTest script now detects the internal link size and whether there
131            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
132            values substituted by "configure". (The RunGrepTest script already did
133            this for UTF-8.) The configure.ac script no longer substitutes the
134            relevant variables.
136        (b) The debugging options /B and /D in pcretest show the compiled bytecode
137            with length and offset values. This means that the output is different
138            for different internal link sizes. Test 2 is skipped for link sizes
139            other than 2 because of this, bypassing the problem. Unfortunately,
140            there was also a test in test 3 (the locale tests) that used /B and
141            failed for link sizes other than 2. Rather than cut the whole test out,
142            I have added a new /Z option to pcretest that replaces the length and
143            offset values with spaces. This is now used to make test 3 independent
144            of link size. (Test 2 will be tidied up later.)
146    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
147        segmentation fault instead of returning the appropriate error message.
149    15. In multiline mode when the newline sequence was set to "any", the pattern
150        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
151        This doesn't seem right; it now treats the CRLF combination as the line
152        ending, and so does not match in that case. It's only a pattern such as ^$
153        that would hit this one: something like ^ABC$ would have failed after \r
154        and then tried again after \r\n.
156    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
157        in an attempt to make files that differ only in their line terminators
158        compare equal. This works on Linux.
160    17. Under certain error circumstances pcregrep might try to free random memory
161        as it exited. This is now fixed, thanks to valgrind.
163    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
164        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
165        was because its rules for how to advance for /g after matching an empty
166        string at the end of a line did not allow for this case. They now check for
167        it specially.
169    20. pcretest is supposed to handle patterns and data of any length, by
170        extending its buffers when necessary. It was getting this wrong when the
171        buffer for a data line had to be extended.
173    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
174        CRLF as a newline sequence.
176    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
177        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
178        I have nevertheless tidied it up.
180    23. Added some casts to kill warnings from HP-UX ia64 compiler.
182    24. Added a man page for pcre-config.
185    Version 7.0 19-Dec-06
186    ---------------------
188     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
189        moving to gcc 4.1.1.
191     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
192        sys/time.h, which is documented as needed for this function. It doesn't
193        seem to matter on Linux, but it showed up on some releases of OS X.
195     3. It seems that there are systems where bytes whose values are greater than
196        127 match isprint() in the "C" locale. The "C" locale should be the
197        default when a C program starts up. In most systems, only ASCII printing
198        characters match isprint(). This difference caused the output from pcretest
199        to vary, making some of the tests fail. I have changed pcretest so that:
201        (a) When it is outputting text in the compiled version of a pattern, bytes
202            other than 32-126 are always shown as hex escapes.
204        (b) When it is outputting text that is a matched part of a subject string,
205            it does the same, unless a different locale has been set for the match
206            (using the /L modifier). In this case, it uses isprint() to decide.
208     4. Fixed a major bug that caused incorrect computation of the amount of memory
209        required for a compiled pattern when options that changed within the
210        pattern affected the logic of the preliminary scan that determines the
211        length. The relevant options are -x, and -i in UTF-8 mode. The result was
212        that the computed length was too small. The symptoms of this bug were
213        either the PCRE error "internal error: code overflow" from pcre_compile(),
214        or a glibc crash with a message such as "pcretest: free(): invalid next
215        size (fast)". Examples of patterns that provoked this bug (shown in
216        pcretest format) are:
218          /(?-x: )/x
219          /(?x)(?-x: \s*#\s*)/
220          /((?i)[\x{c0}])/8
221          /(?i:[\x{c0}])/8
223        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
224        is now done differently.
226     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
227        wrapper classes; (b) implement a new function in the C++ scanner that is
228        more efficient than the old way of doing things because it avoids levels of
229        recursion in the regex matching; (c) add a paragraph to the documentation
230        for the FullMatch() function.
232     6. The escape sequence \n was being treated as whatever was defined as
233        "newline". Not only was this contrary to the documentation, which states
234        that \n is character 10 (hex 0A), but it also went horribly wrong when
235        "newline" was defined as CRLF. This has been fixed.
237     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
238        was being set to -1 for the "end of line" case (supposedly a value that no
239        character can have). Though this value is never used (the check for end of
240        line is "zero bytes in current character"), it caused compiler complaints.
241        I've changed it to 0xffffffff.
243     8. In pcre_version.c, the version string was being built by a sequence of
244        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
245        string (as it is for production releases) called a macro with an empty
246        argument. The C standard says the result of this is undefined. The gcc
247        compiler treats it as an empty string (which was what was wanted) but it is
248        reported that Visual C gives an error. The source has been hacked around to
249        avoid this problem.
251     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
252        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
253        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
254        of them did).
256    10. Originally, pcretest opened its input and output without "b"; then I was
257        told that "b" was needed in some environments, so it was added for release
258        5.0 to both the input and output. (It makes no difference on Unix-like
259        systems.) Later I was told that it is wrong for the input on Windows. I've
260        now abstracted the modes into two macros, to make it easier to fiddle with
261        them, and removed "b" from the input mode under Windows.
263    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
265    12. Added -help and --help to pcretest as an official way of being reminded
266        of the options.
268    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
269        and pcrecpp.cc because they annoy compilers at high warning levels.
271    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
273    15. Fixed an occurrence of == in configure.ac that should have been = (shell
274        scripts are not C programs :-) and which was not noticed because it works
275        on Linux.
277    16. pcretest is supposed to handle any length of pattern and data line (as one
278        line or as a continued sequence of lines) by extending its input buffer if
279        necessary. This feature was broken for very long pattern lines, leading to
280        a string of junk being passed to pcre_compile() if the pattern was longer
281        than about 50K.
283    17. I have done a major re-factoring of the way pcre_compile() computes the
284        amount of memory needed for a compiled pattern. Previously, there was code
285        that made a preliminary scan of the pattern in order to do this. That was
286        OK when PCRE was new, but as the facilities have expanded, it has become
287        harder and harder to keep it in step with the real compile phase, and there
288        have been a number of bugs (see for example, 4 above). I have now found a
289        cunning way of running the real compile function in a "fake" mode that
290        enables it to compute how much memory it would need, while actually only
291        ever using a few hundred bytes of working memory and without too many
292        tests of the mode. This should make future maintenance and development
293        easier. A side effect of this work is that the limit of 200 on the nesting
294        depth of parentheses has been removed (though this was never a serious
295        limitation, I suspect). However, there is a downside: pcre_compile() now
296        runs more slowly than before (30% or more, depending on the pattern). I
297        hope this isn't a big issue. There is no effect on runtime performance.
299    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
300        newline (only possible for the last line of a file) and it was a
301        pattern that set a locale (followed by /Lsomething), pcretest crashed.
303    19. Added additional timing features to pcretest. (1) The -tm option now times
304        matching only, not compiling. (2) Both -t and -tm can be followed, as a
305        separate command line item, by a number that specifies the number of
306        repeats to use when timing. The default is 50000; this gives better
307        precision, but takes uncomfortably long for very large patterns.
309    20. Extended pcre_study() to be more clever in cases where a branch of a
310        subpattern has no definite first character. For example, (a*|b*)[cd] would
311        previously give no result from pcre_study(). Now it recognizes that the
312        first character must be a, b, c, or d.
314    21. There was an incorrect error "recursive call could loop indefinitely" if
315        a subpattern (or the entire pattern) that was being tested for matching an
316        empty string contained only one non-empty item after a nested subpattern.
317        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
318        incorrectly, because the \d was being skipped in the check.
320    22. The pcretest program now has a new pattern option /B and a command line
321        option -b, which is equivalent to adding /B to every pattern. This causes
322        it to show the compiled bytecode, without the additional information that
323        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
324        is the same as /B/I).
326    23. A new optimization is now able automatically to treat some sequences such
327        as a*b as a*+b. More specifically, if something simple (such as a character
328        or a simple class like \d) has an unlimited quantifier, and is followed by
329        something that cannot possibly match the quantified thing, the quantifier
330        is automatically "possessified".
332    24. A recursive reference to a subpattern whose number was greater than 39
333        went wrong under certain circumstances in UTF-8 mode. This bug could also
334        have affected the operation of pcre_study().
336    25. Realized that a little bit of performance could be had by replacing
337        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
339    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
341    27. Possessive quantifiers such as a++ were previously implemented by turning
342        them into atomic groups such as ($>a+). Now they have their own opcodes,
343        which improves performance. This includes the automatically created ones
344        from 23 above.
346    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
347        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
348        the first matched character to be a colon. This applied both to named and
349        numbered groups.
351    29. The ucpinternal.h header file was missing its idempotency #ifdef.
353    30. I was sent a "project" file called libpcre.a.dev which I understand makes
354        building PCRE on Windows easier, so I have included it in the distribution.
356    31. There is now a check in pcretest against a ridiculously large number being
357        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
358        loop, the loop is abandoned.
360    32. Forward references to subpatterns in conditions such as (?(2)...) where
361        subpattern 2 is defined later cause pcre_compile() to search forwards in
362        the pattern for the relevant set of parentheses. This search went wrong
363        when there were unescaped parentheses in a character class, parentheses
364        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
366    33. "Subroutine" calls and backreferences were previously restricted to
367        referencing subpatterns earlier in the regex. This restriction has now
368        been removed.
370    34. Added a number of extra features that are going to be in Perl 5.10. On the
371        whole, these are just syntactic alternatives for features that PCRE had
372        previously implemented using the Python syntax or my own invention. The
373        other formats are all retained for compatibility.
375        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
376            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
377            also .NET compatible.
379        (b) A recursion or subroutine call to a named group can now be defined as
380            (?&name) as well as (?P>name).
382        (c) A backreference to a named group can now be defined as \k<name> or
383            \k'name' as well as (?P=name). The new forms, as well as being in Perl
384            5.10, are also .NET compatible.
386        (d) A conditional reference to a named group can now use the syntax
387            (?(<name>) or (?('name') as well as (?(name).
389        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
390            groups (named and numbered) that are never evaluated inline, but can be
391            called as "subroutines" from elsewhere. In effect, the DEFINE condition
392            is always false. There may be only one alternative in such a group.
394        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
395            as the simple (?(R). The condition is true only if the most recent
396            recursion is that of the given number or name. It does not search out
397            through the entire recursion stack.
399        (g) The escape \gN or \g{N} has been added, where N is a positive or
400            negative number, specifying an absolute or relative reference.
402    35. Tidied to get rid of some further signed/unsigned compiler warnings and
403        some "unreachable code" warnings.
405    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
406        things, this adds five new scripts.
408    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
409        There were also incompatibilities regarding the handling of \Q..\E inside
410        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
411        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
413    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
414        matches an empty string, and forcibly breaks the loop. There were bugs in
415        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
416        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
417        separate and independent bugs (that affected different cases) have been
418        fixed.
420    39. Refactored the code to abolish the use of different opcodes for small
421        capturing bracket numbers. This is a tidy that I avoided doing when I
422        removed the limit on the number of capturing brackets for 3.5 back in 2001.
423        The new approach is not only tidier, it makes it possible to reduce the
424        memory needed to fix the previous bug (38).
426    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
427        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
428        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
429        mode.
431    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
432        report.
434    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
435        copy construction and assignment in the C++ wrapper.
437    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
438        couple of bugs that could have given wrong results in the "--newline=crlf"
439        case.
441    44. Added a number of casts and did some reorganization of signed/unsigned int
442        variables following suggestions from Dair Grant. Also renamed the variable
443        "this" as "item" because it is a C++ keyword.
445    45. Arranged for dftables to add
447          #include "pcre_internal.h"
449        to pcre_chartables.c because without it, gcc 4.x may remove the array
450        definition from the final binary if PCRE is built into a static library and
451        dead code stripping is activated.
453    46. For an unanchored pattern, if a match attempt fails at the start of a
454        newline sequence, and the newline setting is CRLF or ANY, and the next two
455        characters are CRLF, advance by two characters instead of one.
458    Version 6.7 04-Jul-06
459    ---------------------
461     1. In order to handle tests when input lines are enormously long, pcretest has
462        been re-factored so that it automatically extends its buffers when
463        necessary. The code is crude, but this _is_ just a test program. The
464        default size has been increased from 32K to 50K.
466     2. The code in pcre_study() was using the value of the re argument before
467        testing it for NULL. (Of course, in any sensible call of the function, it
468        won't be NULL.)
470     3. The memmove() emulation function in pcre_internal.h, which is used on
471        systems that lack both memmove() and bcopy() - that is, hardly ever -
472        was missing a "static" storage class specifier.
474     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
475        containing an extended class (one that cannot be represented by a bitmap
476        because it contains high-valued characters or Unicode property items, e.g.
477        [\pZ]). Almost always one would set UTF-8 mode when processing such a
478        pattern, but PCRE should not loop if you do not (it no longer does).
479        [Detail: two cases were found: (a) a repeated subpattern containing an
480        extended class; (b) a recursive reference to a subpattern that followed a
481        previous extended class. It wasn't skipping over the extended class
482        correctly when UTF-8 mode was not set.]
484     5. A negated single-character class was not being recognized as fixed-length
485        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
486        compile error "lookbehind assertion is not fixed length".
488     6. The RunPerlTest auxiliary script was showing an unexpected difference
489        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
490        write a Perl script that can interpret lines of an input file either as
491        byte characters or as UTF-8, which is what "perltest" was being required to
492        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
493        can't do is switch easily at run time between having the "use utf8;" pragma
494        or not. In the end, I fudged it by using the RunPerlTest script to insert
495        "use utf8;" explicitly for the UTF-8 tests.
497     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
498        the end of the subject string, contrary to the documentation and to what
499        Perl does. This was true of both matching functions. Now it matches only at
500        the start of the subject and immediately after *internal* newlines.
502     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
503        a pointer to an int instead of a pointer to an unsigned long int. This
504        caused problems on 64-bit systems.
506     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
507        instance of the 'standard' template library not being so standard".
509    10. There was no check on the number of named subpatterns nor the maximum
510        length of a subpattern name. The product of these values is used to compute
511        the size of the memory block for a compiled pattern. By supplying a very
512        long subpattern name and a large number of named subpatterns, the size
513        computation could be caused to overflow. This is now prevented by limiting
514        the length of names to 32 characters, and the number of named subpatterns
515        to 10,000.
517    11. Subpatterns that are repeated with specific counts have to be replicated in
518        the compiled pattern. The size of memory for this was computed from the
519        length of the subpattern and the repeat count. The latter is limited to
520        65535, but there was no limit on the former, meaning that integer overflow
521        could in principle occur. The compiled length of a repeated subpattern is
522        now limited to 30,000 bytes in order to prevent this.
524    12. Added the optional facility to have named substrings with the same name.
526    13. Added the ability to use a named substring as a condition, using the
527        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
528        are numbers (not recommended). Forward references are permitted.
530    14. Added forward references in named backreferences (if you see what I mean).
532    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
533        pattern could run off the end of the subject. For example, the pattern
534        "(?s)(.{1,5})"8 did this with the subject "ab".
536    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
537        PCRE_CASELESS was set when matching characters that were quantified with ?
538        or *.
540    17. A character class other than a single negated character that had a minimum
541        but no maximum quantifier - for example [ab]{6,} - was not handled
542        correctly by pce_dfa_exec(). It would match only one character.
544    18. A valid (though odd) pattern that looked like a POSIX character
545        class but used an invalid character after [ (for example [[,abc,]]) caused
546        pcre_compile() to give the error "Failed: internal error: code overflow" or
547        in some cases to crash with a glibc free() error. This could even happen if
548        the pattern terminated after [[ but there just happened to be a sequence of
549        letters, a binary zero, and a closing ] in the memory that followed.
551    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
552        over the years. Originally (before any Unicode support), just the bottom 8
553        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
554        output from "man perlunicode" includes this:
556          The regular expression compiler produces polymorphic opcodes.  That
557          is, the pattern adapts to the data and automatically switches to
558          the Unicode character scheme when presented with Unicode data--or
559          instead uses a traditional byte scheme when presented with byte
560          data.
562        Sadly, a wide octal escape does not cause a switch, and in a string with
563        no other multibyte characters, these octal escapes are treated as before.
564        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
565        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
566        Unicode string.
568        I have not perpetrated such confusion in PCRE. Up till now, it took just
569        the bottom 8 bits, as in old Perl. I have now made octal escapes with
570        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
571        translate to the appropriate multibyte character.
573    29. Applied some refactoring to reduce the number of warnings from Microsoft
574        and Borland compilers. This has included removing the fudge introduced
575        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
576        a warning about an unused variable.
578    21. PCRE has not included VT (character 0x0b) in the set of whitespace
579        characters since release 4.0, because Perl (from release 5.004) does not.
580        [Or at least, is documented not to: some releases seem to be in conflict
581        with the documentation.] However, when a pattern was studied with
582        pcre_study() and all its branches started with \s, PCRE still included VT
583        as a possible starting character. Of course, this did no harm; it just
584        caused an unnecessary match attempt.
586    22. Removed a now-redundant internal flag bit that recorded the fact that case
587        dependency changed within the pattern. This was once needed for "required
588        byte" processing, but is no longer used. This recovers a now-scarce options
589        bit. Also moved the least significant internal flag bit to the most-
590        significant bit of the word, which was not previously used (hangover from
591        the days when it was an int rather than a uint) to free up another bit for
592        the future.
594    23. Added support for CRLF line endings as well as CR and LF. As well as the
595        default being selectable at build time, it can now be changed at runtime
596        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
597        specify that it is scanning data with non-default line endings.
599    24. Changed the definition of CXXLINK to make it agree with the definition of
600        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
602    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
603        recursions. This makes a big different to stack usage for some patterns.
605    26. If a subpattern containing a named recursion or subroutine reference such
606        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
607        the space required for the compiled pattern went wrong and gave too small a
608        value. Depending on the environment, this could lead to "Failed: internal
609        error: code overflow at offset 49" or "glibc detected double free or
610        corruption" errors.
612    27. Applied patches from Google (a) to support the new newline modes and (b) to
613        advance over multibyte UTF-8 characters in GlobalReplace.
615    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
616        difference for some implementation of PCRE in some Windows version.
618    29. Added some extra testing facilities to pcretest:
620        \q<number>   in a data line sets the "match limit" value
621        \Q<number>   in a data line sets the "match recursion limt" value
622        -S <number>  sets the stack size, where <number> is in megabytes
624        The -S option isn't available for Windows.
627    Version 6.6 06-Feb-06
628    ---------------------
630     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
631        in pcreposix.h. I have copied the definition from pcre.h.
633     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
634        because pcre.h is no longer a built file.
636     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
637        not normally included in the compiled code.
640  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
641  ---------------------  ---------------------

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