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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.2 01-May-07
5    ---------------------
6    
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.
9    
10    
11    Version 7.1 24-Apr-07
12    ---------------------
13    
14     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
15        that is more "standard", making use of automake and other Autotools. There
16        is some re-arrangement of the files and adjustment of comments consequent
17        on this.
18    
19     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
20        for recursive directory scanning broke on some systems because the files
21        are not scanned in any specific order and on different systems the order
22        was different. A call to "sort" has been inserted into RunGrepTest for the
23        approprate test as a short-term fix. In the longer term there may be an
24        alternative.
25    
26     3. I had an email from Eric Raymond about problems translating some of PCRE's
27        man pages to HTML (despite the fact that I distribute HTML pages, some
28        people do their own conversions for various reasons). The problems
29        concerned the use of low-level troff macros .br and .in. I have therefore
30        removed all such uses from the man pages (some were redundant, some could
31        be replaced by .nf/.fi pairs). The 132html script that I use to generate
32        HTML has been updated to handle .nf/.fi and to complain if it encounters
33        .br or .in.
34    
35     4. Updated comments in configure.ac that get placed in config.h.in and also
36        arranged for config.h to be included in the distribution, with the name
37        config.h.generic, for the benefit of those who have to compile without
38        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
39    
40     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
41        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
42        makevp.bat for the current PCRE, using the additional files
43        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
44    
45     6. A Windows user reported a minor discrepancy with test 2, which turned out
46        to be caused by a trailing space on an input line that had got lost in his
47        copy. The trailing space was an accident, so I've just removed it.
48    
49     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
50        that is needed.
51    
52     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
53        as "const" (a) because they are and (b) because it helps the PHP
54        maintainers who have recently made a script to detect big data structures
55        in the php code that should be moved to the .rodata section. I remembered
56        to update Builducptable as well, so it won't revert if ucptable.h is ever
57        re-created.
58    
59     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
60        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
61        order to be able to cut out the UTF-8 tables in the latter when UTF-8
62        support is not required. This saves 1.5-2K of code, which is important in
63        some applications.
64    
65        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
66        so as not to refer to the tables, even though these functions will never be
67        called when UTF-8 support is disabled. Otherwise there are problems with a
68        shared library.
69    
70    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
71    
72        (a) It was defining its arguments as char * instead of void *.
73    
74        (b) It was assuming that all moves were upwards in memory; this was true
75            a long time ago when I wrote it, but is no longer the case.
76    
77        The emulated memove() is provided for those environments that have neither
78        memmove() nor bcopy(). I didn't think anyone used it these days, but that
79        is clearly not the case, as these two bugs were recently reported.
80    
81    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
82        and Detrail to create the HTML documentation, the .txt form of the man
83        pages, and it removes trailing spaces from listed files. It also creates
84        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
85        case, it wraps all the #defines with #ifndefs. This script should be run
86        before "make dist".
87    
88    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
89        with Unicode property support.
90    
91        (a) For a maximizing quantifier, if the two different cases of the
92            character were of different lengths in their UTF-8 codings (there are
93            some cases like this - I found 11), and the matching function had to
94            back up over a mixture of the two cases, it incorrectly assumed they
95            were both the same length.
96    
97        (b) When PCRE was configured to use the heap rather than the stack for
98            recursion during matching, it was not correctly preserving the data for
99            the other case of a UTF-8 character when checking ahead for a match
100            while processing a minimizing repeat. If the check also involved
101            matching a wide character, but failed, corruption could cause an
102            erroneous result when trying to check for a repeat of the original
103            character.
104    
105    13. Some tidying changes to the testing mechanism:
106    
107        (a) The RunTest script now detects the internal link size and whether there
108            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
109            values substituted by "configure". (The RunGrepTest script already did
110            this for UTF-8.) The configure.ac script no longer substitutes the
111            relevant variables.
112    
113        (b) The debugging options /B and /D in pcretest show the compiled bytecode
114            with length and offset values. This means that the output is different
115            for different internal link sizes. Test 2 is skipped for link sizes
116            other than 2 because of this, bypassing the problem. Unfortunately,
117            there was also a test in test 3 (the locale tests) that used /B and
118            failed for link sizes other than 2. Rather than cut the whole test out,
119            I have added a new /Z option to pcretest that replaces the length and
120            offset values with spaces. This is now used to make test 3 independent
121            of link size. (Test 2 will be tidied up later.)
122    
123    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
124        segmentation fault instead of returning the appropriate error message.
125    
126    15. In multiline mode when the newline sequence was set to "any", the pattern
127        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
128        This doesn't seem right; it now treats the CRLF combination as the line
129        ending, and so does not match in that case. It's only a pattern such as ^$
130        that would hit this one: something like ^ABC$ would have failed after \r
131        and then tried again after \r\n.
132    
133    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
134        in an attempt to make files that differ only in their line terminators
135        compare equal. This works on Linux.
136    
137    17. Under certain error circumstances pcregrep might try to free random memory
138        as it exited. This is now fixed, thanks to valgrind.
139    
140    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
141        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
142        was because its rules for how to advance for /g after matching an empty
143        string at the end of a line did not allow for this case. They now check for
144        it specially.
145    
146    20. pcretest is supposed to handle patterns and data of any length, by
147        extending its buffers when necessary. It was getting this wrong when the
148        buffer for a data line had to be extended.
149    
150    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
151        CRLF as a newline sequence.
152    
153    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
154        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
155        I have nevertheless tidied it up.
156    
157    23. Added some casts to kill warnings from HP-UX ia64 compiler.
158    
159    24. Added a man page for pcre-config.
160    
161    
162    Version 7.0 19-Dec-06
163    ---------------------
164    
165     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
166        moving to gcc 4.1.1.
167    
168     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
169        sys/time.h, which is documented as needed for this function. It doesn't
170        seem to matter on Linux, but it showed up on some releases of OS X.
171    
172     3. It seems that there are systems where bytes whose values are greater than
173        127 match isprint() in the "C" locale. The "C" locale should be the
174        default when a C program starts up. In most systems, only ASCII printing
175        characters match isprint(). This difference caused the output from pcretest
176        to vary, making some of the tests fail. I have changed pcretest so that:
177    
178        (a) When it is outputting text in the compiled version of a pattern, bytes
179            other than 32-126 are always shown as hex escapes.
180    
181        (b) When it is outputting text that is a matched part of a subject string,
182            it does the same, unless a different locale has been set for the match
183            (using the /L modifier). In this case, it uses isprint() to decide.
184    
185     4. Fixed a major bug that caused incorrect computation of the amount of memory
186        required for a compiled pattern when options that changed within the
187        pattern affected the logic of the preliminary scan that determines the
188        length. The relevant options are -x, and -i in UTF-8 mode. The result was
189        that the computed length was too small. The symptoms of this bug were
190        either the PCRE error "internal error: code overflow" from pcre_compile(),
191        or a glibc crash with a message such as "pcretest: free(): invalid next
192        size (fast)". Examples of patterns that provoked this bug (shown in
193        pcretest format) are:
194    
195          /(?-x: )/x
196          /(?x)(?-x: \s*#\s*)/
197          /((?i)[\x{c0}])/8
198          /(?i:[\x{c0}])/8
199    
200        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
201        is now done differently.
202    
203     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
204        wrapper classes; (b) implement a new function in the C++ scanner that is
205        more efficient than the old way of doing things because it avoids levels of
206        recursion in the regex matching; (c) add a paragraph to the documentation
207        for the FullMatch() function.
208    
209     6. The escape sequence \n was being treated as whatever was defined as
210        "newline". Not only was this contrary to the documentation, which states
211        that \n is character 10 (hex 0A), but it also went horribly wrong when
212        "newline" was defined as CRLF. This has been fixed.
213    
214     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
215        was being set to -1 for the "end of line" case (supposedly a value that no
216        character can have). Though this value is never used (the check for end of
217        line is "zero bytes in current character"), it caused compiler complaints.
218        I've changed it to 0xffffffff.
219    
220     8. In pcre_version.c, the version string was being built by a sequence of
221        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
222        string (as it is for production releases) called a macro with an empty
223        argument. The C standard says the result of this is undefined. The gcc
224        compiler treats it as an empty string (which was what was wanted) but it is
225        reported that Visual C gives an error. The source has been hacked around to
226        avoid this problem.
227    
228     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
229        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
230        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
231        of them did).
232    
233    10. Originally, pcretest opened its input and output without "b"; then I was
234        told that "b" was needed in some environments, so it was added for release
235        5.0 to both the input and output. (It makes no difference on Unix-like
236        systems.) Later I was told that it is wrong for the input on Windows. I've
237        now abstracted the modes into two macros, to make it easier to fiddle with
238        them, and removed "b" from the input mode under Windows.
239    
240    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
241    
242    12. Added -help and --help to pcretest as an official way of being reminded
243        of the options.
244    
245    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
246        and pcrecpp.cc because they annoy compilers at high warning levels.
247    
248    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
249    
250    15. Fixed an occurrence of == in configure.ac that should have been = (shell
251        scripts are not C programs :-) and which was not noticed because it works
252        on Linux.
253    
254    16. pcretest is supposed to handle any length of pattern and data line (as one
255        line or as a continued sequence of lines) by extending its input buffer if
256        necessary. This feature was broken for very long pattern lines, leading to
257        a string of junk being passed to pcre_compile() if the pattern was longer
258        than about 50K.
259    
260    17. I have done a major re-factoring of the way pcre_compile() computes the
261        amount of memory needed for a compiled pattern. Previously, there was code
262        that made a preliminary scan of the pattern in order to do this. That was
263        OK when PCRE was new, but as the facilities have expanded, it has become
264        harder and harder to keep it in step with the real compile phase, and there
265        have been a number of bugs (see for example, 4 above). I have now found a
266        cunning way of running the real compile function in a "fake" mode that
267        enables it to compute how much memory it would need, while actually only
268        ever using a few hundred bytes of working memory and without too many
269        tests of the mode. This should make future maintenance and development
270        easier. A side effect of this work is that the limit of 200 on the nesting
271        depth of parentheses has been removed (though this was never a serious
272        limitation, I suspect). However, there is a downside: pcre_compile() now
273        runs more slowly than before (30% or more, depending on the pattern). I
274        hope this isn't a big issue. There is no effect on runtime performance.
275    
276    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
277        newline (only possible for the last line of a file) and it was a
278        pattern that set a locale (followed by /Lsomething), pcretest crashed.
279    
280    19. Added additional timing features to pcretest. (1) The -tm option now times
281        matching only, not compiling. (2) Both -t and -tm can be followed, as a
282        separate command line item, by a number that specifies the number of
283        repeats to use when timing. The default is 50000; this gives better
284        precision, but takes uncomfortably long for very large patterns.
285    
286    20. Extended pcre_study() to be more clever in cases where a branch of a
287        subpattern has no definite first character. For example, (a*|b*)[cd] would
288        previously give no result from pcre_study(). Now it recognizes that the
289        first character must be a, b, c, or d.
290    
291    21. There was an incorrect error "recursive call could loop indefinitely" if
292        a subpattern (or the entire pattern) that was being tested for matching an
293        empty string contained only one non-empty item after a nested subpattern.
294        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
295        incorrectly, because the \d was being skipped in the check.
296    
297    22. The pcretest program now has a new pattern option /B and a command line
298        option -b, which is equivalent to adding /B to every pattern. This causes
299        it to show the compiled bytecode, without the additional information that
300        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
301        is the same as /B/I).
302    
303    23. A new optimization is now able automatically to treat some sequences such
304        as a*b as a*+b. More specifically, if something simple (such as a character
305        or a simple class like \d) has an unlimited quantifier, and is followed by
306        something that cannot possibly match the quantified thing, the quantifier
307        is automatically "possessified".
308    
309    24. A recursive reference to a subpattern whose number was greater than 39
310        went wrong under certain circumstances in UTF-8 mode. This bug could also
311        have affected the operation of pcre_study().
312    
313    25. Realized that a little bit of performance could be had by replacing
314        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
315    
316    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
317    
318    27. Possessive quantifiers such as a++ were previously implemented by turning
319        them into atomic groups such as ($>a+). Now they have their own opcodes,
320        which improves performance. This includes the automatically created ones
321        from 23 above.
322    
323    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
324        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
325        the first matched character to be a colon. This applied both to named and
326        numbered groups.
327    
328    29. The ucpinternal.h header file was missing its idempotency #ifdef.
329    
330    30. I was sent a "project" file called libpcre.a.dev which I understand makes
331        building PCRE on Windows easier, so I have included it in the distribution.
332    
333    31. There is now a check in pcretest against a ridiculously large number being
334        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
335        loop, the loop is abandoned.
336    
337    32. Forward references to subpatterns in conditions such as (?(2)...) where
338        subpattern 2 is defined later cause pcre_compile() to search forwards in
339        the pattern for the relevant set of parentheses. This search went wrong
340        when there were unescaped parentheses in a character class, parentheses
341        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
342    
343    33. "Subroutine" calls and backreferences were previously restricted to
344        referencing subpatterns earlier in the regex. This restriction has now
345        been removed.
346    
347    34. Added a number of extra features that are going to be in Perl 5.10. On the
348        whole, these are just syntactic alternatives for features that PCRE had
349        previously implemented using the Python syntax or my own invention. The
350        other formats are all retained for compatibility.
351    
352        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
353            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
354            also .NET compatible.
355    
356        (b) A recursion or subroutine call to a named group can now be defined as
357            (?&name) as well as (?P>name).
358    
359        (c) A backreference to a named group can now be defined as \k<name> or
360            \k'name' as well as (?P=name). The new forms, as well as being in Perl
361            5.10, are also .NET compatible.
362    
363        (d) A conditional reference to a named group can now use the syntax
364            (?(<name>) or (?('name') as well as (?(name).
365    
366        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
367            groups (named and numbered) that are never evaluated inline, but can be
368            called as "subroutines" from elsewhere. In effect, the DEFINE condition
369            is always false. There may be only one alternative in such a group.
370    
371        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
372            as the simple (?(R). The condition is true only if the most recent
373            recursion is that of the given number or name. It does not search out
374            through the entire recursion stack.
375    
376        (g) The escape \gN or \g{N} has been added, where N is a positive or
377            negative number, specifying an absolute or relative reference.
378    
379    35. Tidied to get rid of some further signed/unsigned compiler warnings and
380        some "unreachable code" warnings.
381    
382    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
383        things, this adds five new scripts.
384    
385    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
386        There were also incompatibilities regarding the handling of \Q..\E inside
387        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
388        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
389    
390    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
391        matches an empty string, and forcibly breaks the loop. There were bugs in
392        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
393        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
394        separate and independent bugs (that affected different cases) have been
395        fixed.
396    
397    39. Refactored the code to abolish the use of different opcodes for small
398        capturing bracket numbers. This is a tidy that I avoided doing when I
399        removed the limit on the number of capturing brackets for 3.5 back in 2001.
400        The new approach is not only tidier, it makes it possible to reduce the
401        memory needed to fix the previous bug (38).
402    
403    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
404        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
405        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
406        mode.
407    
408    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
409        report.
410    
411    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
412        copy construction and assignment in the C++ wrapper.
413    
414    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
415        couple of bugs that could have given wrong results in the "--newline=crlf"
416        case.
417    
418    44. Added a number of casts and did some reorganization of signed/unsigned int
419        variables following suggestions from Dair Grant. Also renamed the variable
420        "this" as "item" because it is a C++ keyword.
421    
422    45. Arranged for dftables to add
423    
424          #include "pcre_internal.h"
425    
426        to pcre_chartables.c because without it, gcc 4.x may remove the array
427        definition from the final binary if PCRE is built into a static library and
428        dead code stripping is activated.
429    
430    46. For an unanchored pattern, if a match attempt fails at the start of a
431        newline sequence, and the newline setting is CRLF or ANY, and the next two
432        characters are CRLF, advance by two characters instead of one.
433    
434    
435    Version 6.7 04-Jul-06
436    ---------------------
437    
438     1. In order to handle tests when input lines are enormously long, pcretest has
439        been re-factored so that it automatically extends its buffers when
440        necessary. The code is crude, but this _is_ just a test program. The
441        default size has been increased from 32K to 50K.
442    
443     2. The code in pcre_study() was using the value of the re argument before
444        testing it for NULL. (Of course, in any sensible call of the function, it
445        won't be NULL.)
446    
447     3. The memmove() emulation function in pcre_internal.h, which is used on
448        systems that lack both memmove() and bcopy() - that is, hardly ever -
449        was missing a "static" storage class specifier.
450    
451     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
452        containing an extended class (one that cannot be represented by a bitmap
453        because it contains high-valued characters or Unicode property items, e.g.
454        [\pZ]). Almost always one would set UTF-8 mode when processing such a
455        pattern, but PCRE should not loop if you do not (it no longer does).
456        [Detail: two cases were found: (a) a repeated subpattern containing an
457        extended class; (b) a recursive reference to a subpattern that followed a
458        previous extended class. It wasn't skipping over the extended class
459        correctly when UTF-8 mode was not set.]
460    
461     5. A negated single-character class was not being recognized as fixed-length
462        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
463        compile error "lookbehind assertion is not fixed length".
464    
465     6. The RunPerlTest auxiliary script was showing an unexpected difference
466        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
467        write a Perl script that can interpret lines of an input file either as
468        byte characters or as UTF-8, which is what "perltest" was being required to
469        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
470        can't do is switch easily at run time between having the "use utf8;" pragma
471        or not. In the end, I fudged it by using the RunPerlTest script to insert
472        "use utf8;" explicitly for the UTF-8 tests.
473    
474     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
475        the end of the subject string, contrary to the documentation and to what
476        Perl does. This was true of both matching functions. Now it matches only at
477        the start of the subject and immediately after *internal* newlines.
478    
479     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
480        a pointer to an int instead of a pointer to an unsigned long int. This
481        caused problems on 64-bit systems.
482    
483     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
484        instance of the 'standard' template library not being so standard".
485    
486    10. There was no check on the number of named subpatterns nor the maximum
487        length of a subpattern name. The product of these values is used to compute
488        the size of the memory block for a compiled pattern. By supplying a very
489        long subpattern name and a large number of named subpatterns, the size
490        computation could be caused to overflow. This is now prevented by limiting
491        the length of names to 32 characters, and the number of named subpatterns
492        to 10,000.
493    
494    11. Subpatterns that are repeated with specific counts have to be replicated in
495        the compiled pattern. The size of memory for this was computed from the
496        length of the subpattern and the repeat count. The latter is limited to
497        65535, but there was no limit on the former, meaning that integer overflow
498        could in principle occur. The compiled length of a repeated subpattern is
499        now limited to 30,000 bytes in order to prevent this.
500    
501    12. Added the optional facility to have named substrings with the same name.
502    
503    13. Added the ability to use a named substring as a condition, using the
504        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
505        are numbers (not recommended). Forward references are permitted.
506    
507    14. Added forward references in named backreferences (if you see what I mean).
508    
509    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
510        pattern could run off the end of the subject. For example, the pattern
511        "(?s)(.{1,5})"8 did this with the subject "ab".
512    
513    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
514        PCRE_CASELESS was set when matching characters that were quantified with ?
515        or *.
516    
517    17. A character class other than a single negated character that had a minimum
518        but no maximum quantifier - for example [ab]{6,} - was not handled
519        correctly by pce_dfa_exec(). It would match only one character.
520    
521    18. A valid (though odd) pattern that looked like a POSIX character
522        class but used an invalid character after [ (for example [[,abc,]]) caused
523        pcre_compile() to give the error "Failed: internal error: code overflow" or
524        in some cases to crash with a glibc free() error. This could even happen if
525        the pattern terminated after [[ but there just happened to be a sequence of
526        letters, a binary zero, and a closing ] in the memory that followed.
527    
528    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
529        over the years. Originally (before any Unicode support), just the bottom 8
530        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
531        output from "man perlunicode" includes this:
532    
533          The regular expression compiler produces polymorphic opcodes.  That
534          is, the pattern adapts to the data and automatically switches to
535          the Unicode character scheme when presented with Unicode data--or
536          instead uses a traditional byte scheme when presented with byte
537          data.
538    
539        Sadly, a wide octal escape does not cause a switch, and in a string with
540        no other multibyte characters, these octal escapes are treated as before.
541        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
542        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
543        Unicode string.
544    
545        I have not perpetrated such confusion in PCRE. Up till now, it took just
546        the bottom 8 bits, as in old Perl. I have now made octal escapes with
547        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
548        translate to the appropriate multibyte character.
549    
550    29. Applied some refactoring to reduce the number of warnings from Microsoft
551        and Borland compilers. This has included removing the fudge introduced
552        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
553        a warning about an unused variable.
554    
555    21. PCRE has not included VT (character 0x0b) in the set of whitespace
556        characters since release 4.0, because Perl (from release 5.004) does not.
557        [Or at least, is documented not to: some releases seem to be in conflict
558        with the documentation.] However, when a pattern was studied with
559        pcre_study() and all its branches started with \s, PCRE still included VT
560        as a possible starting character. Of course, this did no harm; it just
561        caused an unnecessary match attempt.
562    
563    22. Removed a now-redundant internal flag bit that recorded the fact that case
564        dependency changed within the pattern. This was once needed for "required
565        byte" processing, but is no longer used. This recovers a now-scarce options
566        bit. Also moved the least significant internal flag bit to the most-
567        significant bit of the word, which was not previously used (hangover from
568        the days when it was an int rather than a uint) to free up another bit for
569        the future.
570    
571    23. Added support for CRLF line endings as well as CR and LF. As well as the
572        default being selectable at build time, it can now be changed at runtime
573        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
574        specify that it is scanning data with non-default line endings.
575    
576    24. Changed the definition of CXXLINK to make it agree with the definition of
577        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
578    
579    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
580        recursions. This makes a big different to stack usage for some patterns.
581    
582    26. If a subpattern containing a named recursion or subroutine reference such
583        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
584        the space required for the compiled pattern went wrong and gave too small a
585        value. Depending on the environment, this could lead to "Failed: internal
586        error: code overflow at offset 49" or "glibc detected double free or
587        corruption" errors.
588    
589    27. Applied patches from Google (a) to support the new newline modes and (b) to
590        advance over multibyte UTF-8 characters in GlobalReplace.
591    
592    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
593        difference for some implementation of PCRE in some Windows version.
594    
595    29. Added some extra testing facilities to pcretest:
596    
597        \q<number>   in a data line sets the "match limit" value
598        \Q<number>   in a data line sets the "match recursion limt" value
599        -S <number>  sets the stack size, where <number> is in megabytes
600    
601        The -S option isn't available for Windows.
602    
603    
604    Version 6.6 06-Feb-06
605    ---------------------
606    
607     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
608        in pcreposix.h. I have copied the definition from pcre.h.
609    
610     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
611        because pcre.h is no longer a built file.
612    
613     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
614        not normally included in the compiled code.
615    
616    
617  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
618  ---------------------  ---------------------
619    

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