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revision 87 by nigel, Sat Feb 24 21:41:21 2007 UTC revision 155 by ph10, Tue Apr 24 13:36:11 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.1 24-Apr-07
5    ---------------------
6    
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other Autotools. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
11    
12     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
13        for recursive directory scanning broke on some systems because the files
14        are not scanned in any specific order and on different systems the order
15        was different. A call to "sort" has been inserted into RunGrepTest for the
16        approprate test as a short-term fix. In the longer term there may be an
17        alternative.
18    
19     3. I had an email from Eric Raymond about problems translating some of PCRE's
20        man pages to HTML (despite the fact that I distribute HTML pages, some
21        people do their own conversions for various reasons). The problems
22        concerned the use of low-level troff macros .br and .in. I have therefore
23        removed all such uses from the man pages (some were redundant, some could
24        be replaced by .nf/.fi pairs). The 132html script that I use to generate
25        HTML has been updated to handle .nf/.fi and to complain if it encounters
26        .br or .in.
27    
28     4. Updated comments in configure.ac that get placed in config.h.in and also
29        arranged for config.h to be included in the distribution, with the name
30        config.h.generic, for the benefit of those who have to compile without
31        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
32    
33     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
34        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
35        makevp.bat for the current PCRE, using the additional files
36        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
37    
38     6. A Windows user reported a minor discrepancy with test 2, which turned out
39        to be caused by a trailing space on an input line that had got lost in his
40        copy. The trailing space was an accident, so I've just removed it.
41    
42     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
43        that is needed.
44    
45     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
46        as "const" (a) because they are and (b) because it helps the PHP
47        maintainers who have recently made a script to detect big data structures
48        in the php code that should be moved to the .rodata section. I remembered
49        to update Builducptable as well, so it won't revert if ucptable.h is ever
50        re-created.
51    
52     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
53        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
54        order to be able to cut out the UTF-8 tables in the latter when UTF-8
55        support is not required. This saves 1.5-2K of code, which is important in
56        some applications.
57    
58        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
59        so as not to refer to the tables, even though these functions will never be
60        called when UTF-8 support is disabled. Otherwise there are problems with a
61        shared library.
62    
63    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
64    
65        (a) It was defining its arguments as char * instead of void *.
66    
67        (b) It was assuming that all moves were upwards in memory; this was true
68            a long time ago when I wrote it, but is no longer the case.
69    
70        The emulated memove() is provided for those environments that have neither
71        memmove() nor bcopy(). I didn't think anyone used it these days, but that
72        is clearly not the case, as these two bugs were recently reported.
73    
74    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
75        and Detrail to create the HTML documentation, the .txt form of the man
76        pages, and it removes trailing spaces from listed files. It also creates
77        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
78        case, it wraps all the #defines with #ifndefs. This script should be run
79        before "make dist".
80    
81    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
82        with Unicode property support.
83    
84        (a) For a maximizing quantifier, if the two different cases of the
85            character were of different lengths in their UTF-8 codings (there are
86            some cases like this - I found 11), and the matching function had to
87            back up over a mixture of the two cases, it incorrectly assumed they
88            were both the same length.
89    
90        (b) When PCRE was configured to use the heap rather than the stack for
91            recursion during matching, it was not correctly preserving the data for
92            the other case of a UTF-8 character when checking ahead for a match
93            while processing a minimizing repeat. If the check also involved
94            matching a wide character, but failed, corruption could cause an
95            erroneous result when trying to check for a repeat of the original
96            character.
97    
98    13. Some tidying changes to the testing mechanism:
99    
100        (a) The RunTest script now detects the internal link size and whether there
101            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
102            values substituted by "configure". (The RunGrepTest script already did
103            this for UTF-8.) The configure.ac script no longer substitutes the
104            relevant variables.
105    
106        (b) The debugging options /B and /D in pcretest show the compiled bytecode
107            with length and offset values. This means that the output is different
108            for different internal link sizes. Test 2 is skipped for link sizes
109            other than 2 because of this, bypassing the problem. Unfortunately,
110            there was also a test in test 3 (the locale tests) that used /B and
111            failed for link sizes other than 2. Rather than cut the whole test out,
112            I have added a new /Z option to pcretest that replaces the length and
113            offset values with spaces. This is now used to make test 3 independent
114            of link size. (Test 2 will be tidied up later.)
115    
116    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
117        segmentation fault instead of returning the appropriate error message.
118    
119    15. In multiline mode when the newline sequence was set to "any", the pattern
120        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
121        This doesn't seem right; it now treats the CRLF combination as the line
122        ending, and so does not match in that case. It's only a pattern such as ^$
123        that would hit this one: something like ^ABC$ would have failed after \r
124        and then tried again after \r\n.
125    
126    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
127        in an attempt to make files that differ only in their line terminators
128        compare equal. This works on Linux.
129    
130    17. Under certain error circumstances pcregrep might try to free random memory
131        as it exited. This is now fixed, thanks to valgrind.
132    
133    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
134        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
135        was because its rules for how to advance for /g after matching an empty
136        string at the end of a line did not allow for this case. They now check for
137        it specially.
138    
139    20. pcretest is supposed to handle patterns and data of any length, by
140        extending its buffers when necessary. It was getting this wrong when the
141        buffer for a data line had to be extended.
142    
143    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
144        CRLF as a newline sequence.
145    
146    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
147        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
148        I have nevertheless tidied it up.
149    
150    23. Added some casts to kill warnings from HP-UX ia64 compiler.
151    
152    24. Added a man page for pcre-config.
153    
154    
155    Version 7.0 19-Dec-06
156    ---------------------
157    
158     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
159        moving to gcc 4.1.1.
160    
161     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
162        sys/time.h, which is documented as needed for this function. It doesn't
163        seem to matter on Linux, but it showed up on some releases of OS X.
164    
165     3. It seems that there are systems where bytes whose values are greater than
166        127 match isprint() in the "C" locale. The "C" locale should be the
167        default when a C program starts up. In most systems, only ASCII printing
168        characters match isprint(). This difference caused the output from pcretest
169        to vary, making some of the tests fail. I have changed pcretest so that:
170    
171        (a) When it is outputting text in the compiled version of a pattern, bytes
172            other than 32-126 are always shown as hex escapes.
173    
174        (b) When it is outputting text that is a matched part of a subject string,
175            it does the same, unless a different locale has been set for the match
176            (using the /L modifier). In this case, it uses isprint() to decide.
177    
178     4. Fixed a major bug that caused incorrect computation of the amount of memory
179        required for a compiled pattern when options that changed within the
180        pattern affected the logic of the preliminary scan that determines the
181        length. The relevant options are -x, and -i in UTF-8 mode. The result was
182        that the computed length was too small. The symptoms of this bug were
183        either the PCRE error "internal error: code overflow" from pcre_compile(),
184        or a glibc crash with a message such as "pcretest: free(): invalid next
185        size (fast)". Examples of patterns that provoked this bug (shown in
186        pcretest format) are:
187    
188          /(?-x: )/x
189          /(?x)(?-x: \s*#\s*)/
190          /((?i)[\x{c0}])/8
191          /(?i:[\x{c0}])/8
192    
193        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
194        is now done differently.
195    
196     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
197        wrapper classes; (b) implement a new function in the C++ scanner that is
198        more efficient than the old way of doing things because it avoids levels of
199        recursion in the regex matching; (c) add a paragraph to the documentation
200        for the FullMatch() function.
201    
202     6. The escape sequence \n was being treated as whatever was defined as
203        "newline". Not only was this contrary to the documentation, which states
204        that \n is character 10 (hex 0A), but it also went horribly wrong when
205        "newline" was defined as CRLF. This has been fixed.
206    
207     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
208        was being set to -1 for the "end of line" case (supposedly a value that no
209        character can have). Though this value is never used (the check for end of
210        line is "zero bytes in current character"), it caused compiler complaints.
211        I've changed it to 0xffffffff.
212    
213     8. In pcre_version.c, the version string was being built by a sequence of
214        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
215        string (as it is for production releases) called a macro with an empty
216        argument. The C standard says the result of this is undefined. The gcc
217        compiler treats it as an empty string (which was what was wanted) but it is
218        reported that Visual C gives an error. The source has been hacked around to
219        avoid this problem.
220    
221     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
222        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
223        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
224        of them did).
225    
226    10. Originally, pcretest opened its input and output without "b"; then I was
227        told that "b" was needed in some environments, so it was added for release
228        5.0 to both the input and output. (It makes no difference on Unix-like
229        systems.) Later I was told that it is wrong for the input on Windows. I've
230        now abstracted the modes into two macros, to make it easier to fiddle with
231        them, and removed "b" from the input mode under Windows.
232    
233    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
234    
235    12. Added -help and --help to pcretest as an official way of being reminded
236        of the options.
237    
238    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
239        and pcrecpp.cc because they annoy compilers at high warning levels.
240    
241    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
242    
243    15. Fixed an occurrence of == in configure.ac that should have been = (shell
244        scripts are not C programs :-) and which was not noticed because it works
245        on Linux.
246    
247    16. pcretest is supposed to handle any length of pattern and data line (as one
248        line or as a continued sequence of lines) by extending its input buffer if
249        necessary. This feature was broken for very long pattern lines, leading to
250        a string of junk being passed to pcre_compile() if the pattern was longer
251        than about 50K.
252    
253    17. I have done a major re-factoring of the way pcre_compile() computes the
254        amount of memory needed for a compiled pattern. Previously, there was code
255        that made a preliminary scan of the pattern in order to do this. That was
256        OK when PCRE was new, but as the facilities have expanded, it has become
257        harder and harder to keep it in step with the real compile phase, and there
258        have been a number of bugs (see for example, 4 above). I have now found a
259        cunning way of running the real compile function in a "fake" mode that
260        enables it to compute how much memory it would need, while actually only
261        ever using a few hundred bytes of working memory and without too many
262        tests of the mode. This should make future maintenance and development
263        easier. A side effect of this work is that the limit of 200 on the nesting
264        depth of parentheses has been removed (though this was never a serious
265        limitation, I suspect). However, there is a downside: pcre_compile() now
266        runs more slowly than before (30% or more, depending on the pattern). I
267        hope this isn't a big issue. There is no effect on runtime performance.
268    
269    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
270        newline (only possible for the last line of a file) and it was a
271        pattern that set a locale (followed by /Lsomething), pcretest crashed.
272    
273    19. Added additional timing features to pcretest. (1) The -tm option now times
274        matching only, not compiling. (2) Both -t and -tm can be followed, as a
275        separate command line item, by a number that specifies the number of
276        repeats to use when timing. The default is 50000; this gives better
277        precision, but takes uncomfortably long for very large patterns.
278    
279    20. Extended pcre_study() to be more clever in cases where a branch of a
280        subpattern has no definite first character. For example, (a*|b*)[cd] would
281        previously give no result from pcre_study(). Now it recognizes that the
282        first character must be a, b, c, or d.
283    
284    21. There was an incorrect error "recursive call could loop indefinitely" if
285        a subpattern (or the entire pattern) that was being tested for matching an
286        empty string contained only one non-empty item after a nested subpattern.
287        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
288        incorrectly, because the \d was being skipped in the check.
289    
290    22. The pcretest program now has a new pattern option /B and a command line
291        option -b, which is equivalent to adding /B to every pattern. This causes
292        it to show the compiled bytecode, without the additional information that
293        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
294        is the same as /B/I).
295    
296    23. A new optimization is now able automatically to treat some sequences such
297        as a*b as a*+b. More specifically, if something simple (such as a character
298        or a simple class like \d) has an unlimited quantifier, and is followed by
299        something that cannot possibly match the quantified thing, the quantifier
300        is automatically "possessified".
301    
302    24. A recursive reference to a subpattern whose number was greater than 39
303        went wrong under certain circumstances in UTF-8 mode. This bug could also
304        have affected the operation of pcre_study().
305    
306    25. Realized that a little bit of performance could be had by replacing
307        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
308    
309    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
310    
311    27. Possessive quantifiers such as a++ were previously implemented by turning
312        them into atomic groups such as ($>a+). Now they have their own opcodes,
313        which improves performance. This includes the automatically created ones
314        from 23 above.
315    
316    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
317        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
318        the first matched character to be a colon. This applied both to named and
319        numbered groups.
320    
321    29. The ucpinternal.h header file was missing its idempotency #ifdef.
322    
323    30. I was sent a "project" file called libpcre.a.dev which I understand makes
324        building PCRE on Windows easier, so I have included it in the distribution.
325    
326    31. There is now a check in pcretest against a ridiculously large number being
327        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
328        loop, the loop is abandoned.
329    
330    32. Forward references to subpatterns in conditions such as (?(2)...) where
331        subpattern 2 is defined later cause pcre_compile() to search forwards in
332        the pattern for the relevant set of parentheses. This search went wrong
333        when there were unescaped parentheses in a character class, parentheses
334        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
335    
336    33. "Subroutine" calls and backreferences were previously restricted to
337        referencing subpatterns earlier in the regex. This restriction has now
338        been removed.
339    
340    34. Added a number of extra features that are going to be in Perl 5.10. On the
341        whole, these are just syntactic alternatives for features that PCRE had
342        previously implemented using the Python syntax or my own invention. The
343        other formats are all retained for compatibility.
344    
345        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
346            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
347            also .NET compatible.
348    
349        (b) A recursion or subroutine call to a named group can now be defined as
350            (?&name) as well as (?P>name).
351    
352        (c) A backreference to a named group can now be defined as \k<name> or
353            \k'name' as well as (?P=name). The new forms, as well as being in Perl
354            5.10, are also .NET compatible.
355    
356        (d) A conditional reference to a named group can now use the syntax
357            (?(<name>) or (?('name') as well as (?(name).
358    
359        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
360            groups (named and numbered) that are never evaluated inline, but can be
361            called as "subroutines" from elsewhere. In effect, the DEFINE condition
362            is always false. There may be only one alternative in such a group.
363    
364        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
365            as the simple (?(R). The condition is true only if the most recent
366            recursion is that of the given number or name. It does not search out
367            through the entire recursion stack.
368    
369        (g) The escape \gN or \g{N} has been added, where N is a positive or
370            negative number, specifying an absolute or relative reference.
371    
372    35. Tidied to get rid of some further signed/unsigned compiler warnings and
373        some "unreachable code" warnings.
374    
375    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
376        things, this adds five new scripts.
377    
378    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
379        There were also incompatibilities regarding the handling of \Q..\E inside
380        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
381        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
382    
383    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
384        matches an empty string, and forcibly breaks the loop. There were bugs in
385        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
386        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
387        separate and independent bugs (that affected different cases) have been
388        fixed.
389    
390    39. Refactored the code to abolish the use of different opcodes for small
391        capturing bracket numbers. This is a tidy that I avoided doing when I
392        removed the limit on the number of capturing brackets for 3.5 back in 2001.
393        The new approach is not only tidier, it makes it possible to reduce the
394        memory needed to fix the previous bug (38).
395    
396    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
397        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
398        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
399        mode.
400    
401    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
402        report.
403    
404    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
405        copy construction and assignment in the C++ wrapper.
406    
407    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
408        couple of bugs that could have given wrong results in the "--newline=crlf"
409        case.
410    
411    44. Added a number of casts and did some reorganization of signed/unsigned int
412        variables following suggestions from Dair Grant. Also renamed the variable
413        "this" as "item" because it is a C++ keyword.
414    
415    45. Arranged for dftables to add
416    
417          #include "pcre_internal.h"
418    
419        to pcre_chartables.c because without it, gcc 4.x may remove the array
420        definition from the final binary if PCRE is built into a static library and
421        dead code stripping is activated.
422    
423    46. For an unanchored pattern, if a match attempt fails at the start of a
424        newline sequence, and the newline setting is CRLF or ANY, and the next two
425        characters are CRLF, advance by two characters instead of one.
426    
427    
428    Version 6.7 04-Jul-06
429    ---------------------
430    
431     1. In order to handle tests when input lines are enormously long, pcretest has
432        been re-factored so that it automatically extends its buffers when
433        necessary. The code is crude, but this _is_ just a test program. The
434        default size has been increased from 32K to 50K.
435    
436     2. The code in pcre_study() was using the value of the re argument before
437        testing it for NULL. (Of course, in any sensible call of the function, it
438        won't be NULL.)
439    
440     3. The memmove() emulation function in pcre_internal.h, which is used on
441        systems that lack both memmove() and bcopy() - that is, hardly ever -
442        was missing a "static" storage class specifier.
443    
444     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
445        containing an extended class (one that cannot be represented by a bitmap
446        because it contains high-valued characters or Unicode property items, e.g.
447        [\pZ]). Almost always one would set UTF-8 mode when processing such a
448        pattern, but PCRE should not loop if you do not (it no longer does).
449        [Detail: two cases were found: (a) a repeated subpattern containing an
450        extended class; (b) a recursive reference to a subpattern that followed a
451        previous extended class. It wasn't skipping over the extended class
452        correctly when UTF-8 mode was not set.]
453    
454     5. A negated single-character class was not being recognized as fixed-length
455        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
456        compile error "lookbehind assertion is not fixed length".
457    
458     6. The RunPerlTest auxiliary script was showing an unexpected difference
459        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
460        write a Perl script that can interpret lines of an input file either as
461        byte characters or as UTF-8, which is what "perltest" was being required to
462        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
463        can't do is switch easily at run time between having the "use utf8;" pragma
464        or not. In the end, I fudged it by using the RunPerlTest script to insert
465        "use utf8;" explicitly for the UTF-8 tests.
466    
467     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
468        the end of the subject string, contrary to the documentation and to what
469        Perl does. This was true of both matching functions. Now it matches only at
470        the start of the subject and immediately after *internal* newlines.
471    
472     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
473        a pointer to an int instead of a pointer to an unsigned long int. This
474        caused problems on 64-bit systems.
475    
476     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
477        instance of the 'standard' template library not being so standard".
478    
479    10. There was no check on the number of named subpatterns nor the maximum
480        length of a subpattern name. The product of these values is used to compute
481        the size of the memory block for a compiled pattern. By supplying a very
482        long subpattern name and a large number of named subpatterns, the size
483        computation could be caused to overflow. This is now prevented by limiting
484        the length of names to 32 characters, and the number of named subpatterns
485        to 10,000.
486    
487    11. Subpatterns that are repeated with specific counts have to be replicated in
488        the compiled pattern. The size of memory for this was computed from the
489        length of the subpattern and the repeat count. The latter is limited to
490        65535, but there was no limit on the former, meaning that integer overflow
491        could in principle occur. The compiled length of a repeated subpattern is
492        now limited to 30,000 bytes in order to prevent this.
493    
494    12. Added the optional facility to have named substrings with the same name.
495    
496    13. Added the ability to use a named substring as a condition, using the
497        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
498        are numbers (not recommended). Forward references are permitted.
499    
500    14. Added forward references in named backreferences (if you see what I mean).
501    
502    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
503        pattern could run off the end of the subject. For example, the pattern
504        "(?s)(.{1,5})"8 did this with the subject "ab".
505    
506    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
507        PCRE_CASELESS was set when matching characters that were quantified with ?
508        or *.
509    
510    17. A character class other than a single negated character that had a minimum
511        but no maximum quantifier - for example [ab]{6,} - was not handled
512        correctly by pce_dfa_exec(). It would match only one character.
513    
514    18. A valid (though odd) pattern that looked like a POSIX character
515        class but used an invalid character after [ (for example [[,abc,]]) caused
516        pcre_compile() to give the error "Failed: internal error: code overflow" or
517        in some cases to crash with a glibc free() error. This could even happen if
518        the pattern terminated after [[ but there just happened to be a sequence of
519        letters, a binary zero, and a closing ] in the memory that followed.
520    
521    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
522        over the years. Originally (before any Unicode support), just the bottom 8
523        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
524        output from "man perlunicode" includes this:
525    
526          The regular expression compiler produces polymorphic opcodes.  That
527          is, the pattern adapts to the data and automatically switches to
528          the Unicode character scheme when presented with Unicode data--or
529          instead uses a traditional byte scheme when presented with byte
530          data.
531    
532        Sadly, a wide octal escape does not cause a switch, and in a string with
533        no other multibyte characters, these octal escapes are treated as before.
534        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
535        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
536        Unicode string.
537    
538        I have not perpetrated such confusion in PCRE. Up till now, it took just
539        the bottom 8 bits, as in old Perl. I have now made octal escapes with
540        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
541        translate to the appropriate multibyte character.
542    
543    29. Applied some refactoring to reduce the number of warnings from Microsoft
544        and Borland compilers. This has included removing the fudge introduced
545        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
546        a warning about an unused variable.
547    
548    21. PCRE has not included VT (character 0x0b) in the set of whitespace
549        characters since release 4.0, because Perl (from release 5.004) does not.
550        [Or at least, is documented not to: some releases seem to be in conflict
551        with the documentation.] However, when a pattern was studied with
552        pcre_study() and all its branches started with \s, PCRE still included VT
553        as a possible starting character. Of course, this did no harm; it just
554        caused an unnecessary match attempt.
555    
556    22. Removed a now-redundant internal flag bit that recorded the fact that case
557        dependency changed within the pattern. This was once needed for "required
558        byte" processing, but is no longer used. This recovers a now-scarce options
559        bit. Also moved the least significant internal flag bit to the most-
560        significant bit of the word, which was not previously used (hangover from
561        the days when it was an int rather than a uint) to free up another bit for
562        the future.
563    
564    23. Added support for CRLF line endings as well as CR and LF. As well as the
565        default being selectable at build time, it can now be changed at runtime
566        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
567        specify that it is scanning data with non-default line endings.
568    
569    24. Changed the definition of CXXLINK to make it agree with the definition of
570        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
571    
572    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
573        recursions. This makes a big different to stack usage for some patterns.
574    
575    26. If a subpattern containing a named recursion or subroutine reference such
576        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
577        the space required for the compiled pattern went wrong and gave too small a
578        value. Depending on the environment, this could lead to "Failed: internal
579        error: code overflow at offset 49" or "glibc detected double free or
580        corruption" errors.
581    
582    27. Applied patches from Google (a) to support the new newline modes and (b) to
583        advance over multibyte UTF-8 characters in GlobalReplace.
584    
585    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
586        difference for some implementation of PCRE in some Windows version.
587    
588    29. Added some extra testing facilities to pcretest:
589    
590        \q<number>   in a data line sets the "match limit" value
591        \Q<number>   in a data line sets the "match recursion limt" value
592        -S <number>  sets the stack size, where <number> is in megabytes
593    
594        The -S option isn't available for Windows.
595    
596    
597    Version 6.6 06-Feb-06
598    ---------------------
599    
600     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
601        in pcreposix.h. I have copied the definition from pcre.h.
602    
603     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
604        because pcre.h is no longer a built file.
605    
606     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
607        not normally included in the compiled code.
608    
609    
610  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
611  ---------------------  ---------------------
612    

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