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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     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.
12    
13     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
14    
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.
19    
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.
24    
25     6. Added more features from the forthcoming Perl 5.10:
26    
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.
29    
30        (b) (?+n) is also a relative subroutine call; it refers to the nth next
31            to be opened parentheses.
32    
33        (c) Conditions that refer to capturing parentheses can be specified
34            relatively, for example, (?(-2)... or (?(+3)...
35    
36        (d) \K resets the start of the current match so that everything before
37            is not part of it.
38    
39     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
40        PCRE_INFO_JCHANGED.
41    
42    
43    Version 7.1 24-Apr-07
44    ---------------------
45    
46     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
47        that is more "standard", making use of automake and other Autotools. There
48        is some re-arrangement of the files and adjustment of comments consequent
49        on this.
50    
51     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
52        for recursive directory scanning broke on some systems because the files
53        are not scanned in any specific order and on different systems the order
54        was different. A call to "sort" has been inserted into RunGrepTest for the
55        approprate test as a short-term fix. In the longer term there may be an
56        alternative.
57    
58     3. I had an email from Eric Raymond about problems translating some of PCRE's
59        man pages to HTML (despite the fact that I distribute HTML pages, some
60        people do their own conversions for various reasons). The problems
61        concerned the use of low-level troff macros .br and .in. I have therefore
62        removed all such uses from the man pages (some were redundant, some could
63        be replaced by .nf/.fi pairs). The 132html script that I use to generate
64        HTML has been updated to handle .nf/.fi and to complain if it encounters
65        .br or .in.
66    
67     4. Updated comments in configure.ac that get placed in config.h.in and also
68        arranged for config.h to be included in the distribution, with the name
69        config.h.generic, for the benefit of those who have to compile without
70        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
71    
72     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
73        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
74        makevp.bat for the current PCRE, using the additional files
75        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
76    
77     6. A Windows user reported a minor discrepancy with test 2, which turned out
78        to be caused by a trailing space on an input line that had got lost in his
79        copy. The trailing space was an accident, so I've just removed it.
80    
81     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
82        that is needed.
83    
84     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
85        as "const" (a) because they are and (b) because it helps the PHP
86        maintainers who have recently made a script to detect big data structures
87        in the php code that should be moved to the .rodata section. I remembered
88        to update Builducptable as well, so it won't revert if ucptable.h is ever
89        re-created.
90    
91     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
92        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
93        order to be able to cut out the UTF-8 tables in the latter when UTF-8
94        support is not required. This saves 1.5-2K of code, which is important in
95        some applications.
96    
97        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
98        so as not to refer to the tables, even though these functions will never be
99        called when UTF-8 support is disabled. Otherwise there are problems with a
100        shared library.
101    
102    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
103    
104        (a) It was defining its arguments as char * instead of void *.
105    
106        (b) It was assuming that all moves were upwards in memory; this was true
107            a long time ago when I wrote it, but is no longer the case.
108    
109        The emulated memove() is provided for those environments that have neither
110        memmove() nor bcopy(). I didn't think anyone used it these days, but that
111        is clearly not the case, as these two bugs were recently reported.
112    
113    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
114        and Detrail to create the HTML documentation, the .txt form of the man
115        pages, and it removes trailing spaces from listed files. It also creates
116        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
117        case, it wraps all the #defines with #ifndefs. This script should be run
118        before "make dist".
119    
120    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
121        with Unicode property support.
122    
123        (a) For a maximizing quantifier, if the two different cases of the
124            character were of different lengths in their UTF-8 codings (there are
125            some cases like this - I found 11), and the matching function had to
126            back up over a mixture of the two cases, it incorrectly assumed they
127            were both the same length.
128    
129        (b) When PCRE was configured to use the heap rather than the stack for
130            recursion during matching, it was not correctly preserving the data for
131            the other case of a UTF-8 character when checking ahead for a match
132            while processing a minimizing repeat. If the check also involved
133            matching a wide character, but failed, corruption could cause an
134            erroneous result when trying to check for a repeat of the original
135            character.
136    
137    13. Some tidying changes to the testing mechanism:
138    
139        (a) The RunTest script now detects the internal link size and whether there
140            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
141            values substituted by "configure". (The RunGrepTest script already did
142            this for UTF-8.) The configure.ac script no longer substitutes the
143            relevant variables.
144    
145        (b) The debugging options /B and /D in pcretest show the compiled bytecode
146            with length and offset values. This means that the output is different
147            for different internal link sizes. Test 2 is skipped for link sizes
148            other than 2 because of this, bypassing the problem. Unfortunately,
149            there was also a test in test 3 (the locale tests) that used /B and
150            failed for link sizes other than 2. Rather than cut the whole test out,
151            I have added a new /Z option to pcretest that replaces the length and
152            offset values with spaces. This is now used to make test 3 independent
153            of link size. (Test 2 will be tidied up later.)
154    
155    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
156        segmentation fault instead of returning the appropriate error message.
157    
158    15. In multiline mode when the newline sequence was set to "any", the pattern
159        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
160        This doesn't seem right; it now treats the CRLF combination as the line
161        ending, and so does not match in that case. It's only a pattern such as ^$
162        that would hit this one: something like ^ABC$ would have failed after \r
163        and then tried again after \r\n.
164    
165    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
166        in an attempt to make files that differ only in their line terminators
167        compare equal. This works on Linux.
168    
169    17. Under certain error circumstances pcregrep might try to free random memory
170        as it exited. This is now fixed, thanks to valgrind.
171    
172    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
173        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
174        was because its rules for how to advance for /g after matching an empty
175        string at the end of a line did not allow for this case. They now check for
176        it specially.
177    
178    20. pcretest is supposed to handle patterns and data of any length, by
179        extending its buffers when necessary. It was getting this wrong when the
180        buffer for a data line had to be extended.
181    
182    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
183        CRLF as a newline sequence.
184    
185    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
186        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
187        I have nevertheless tidied it up.
188    
189    23. Added some casts to kill warnings from HP-UX ia64 compiler.
190    
191    24. Added a man page for pcre-config.
192    
193    
194    Version 7.0 19-Dec-06
195    ---------------------
196    
197     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
198        moving to gcc 4.1.1.
199    
200     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
201        sys/time.h, which is documented as needed for this function. It doesn't
202        seem to matter on Linux, but it showed up on some releases of OS X.
203    
204     3. It seems that there are systems where bytes whose values are greater than
205        127 match isprint() in the "C" locale. The "C" locale should be the
206        default when a C program starts up. In most systems, only ASCII printing
207        characters match isprint(). This difference caused the output from pcretest
208        to vary, making some of the tests fail. I have changed pcretest so that:
209    
210        (a) When it is outputting text in the compiled version of a pattern, bytes
211            other than 32-126 are always shown as hex escapes.
212    
213        (b) When it is outputting text that is a matched part of a subject string,
214            it does the same, unless a different locale has been set for the match
215            (using the /L modifier). In this case, it uses isprint() to decide.
216    
217     4. Fixed a major bug that caused incorrect computation of the amount of memory
218        required for a compiled pattern when options that changed within the
219        pattern affected the logic of the preliminary scan that determines the
220        length. The relevant options are -x, and -i in UTF-8 mode. The result was
221        that the computed length was too small. The symptoms of this bug were
222        either the PCRE error "internal error: code overflow" from pcre_compile(),
223        or a glibc crash with a message such as "pcretest: free(): invalid next
224        size (fast)". Examples of patterns that provoked this bug (shown in
225        pcretest format) are:
226    
227          /(?-x: )/x
228          /(?x)(?-x: \s*#\s*)/
229          /((?i)[\x{c0}])/8
230          /(?i:[\x{c0}])/8
231    
232        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
233        is now done differently.
234    
235     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
236        wrapper classes; (b) implement a new function in the C++ scanner that is
237        more efficient than the old way of doing things because it avoids levels of
238        recursion in the regex matching; (c) add a paragraph to the documentation
239        for the FullMatch() function.
240    
241     6. The escape sequence \n was being treated as whatever was defined as
242        "newline". Not only was this contrary to the documentation, which states
243        that \n is character 10 (hex 0A), but it also went horribly wrong when
244        "newline" was defined as CRLF. This has been fixed.
245    
246     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
247        was being set to -1 for the "end of line" case (supposedly a value that no
248        character can have). Though this value is never used (the check for end of
249        line is "zero bytes in current character"), it caused compiler complaints.
250        I've changed it to 0xffffffff.
251    
252     8. In pcre_version.c, the version string was being built by a sequence of
253        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
254        string (as it is for production releases) called a macro with an empty
255        argument. The C standard says the result of this is undefined. The gcc
256        compiler treats it as an empty string (which was what was wanted) but it is
257        reported that Visual C gives an error. The source has been hacked around to
258        avoid this problem.
259    
260     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
261        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
262        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
263        of them did).
264    
265    10. Originally, pcretest opened its input and output without "b"; then I was
266        told that "b" was needed in some environments, so it was added for release
267        5.0 to both the input and output. (It makes no difference on Unix-like
268        systems.) Later I was told that it is wrong for the input on Windows. I've
269        now abstracted the modes into two macros, to make it easier to fiddle with
270        them, and removed "b" from the input mode under Windows.
271    
272    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
273    
274    12. Added -help and --help to pcretest as an official way of being reminded
275        of the options.
276    
277    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
278        and pcrecpp.cc because they annoy compilers at high warning levels.
279    
280    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
281    
282    15. Fixed an occurrence of == in configure.ac that should have been = (shell
283        scripts are not C programs :-) and which was not noticed because it works
284        on Linux.
285    
286    16. pcretest is supposed to handle any length of pattern and data line (as one
287        line or as a continued sequence of lines) by extending its input buffer if
288        necessary. This feature was broken for very long pattern lines, leading to
289        a string of junk being passed to pcre_compile() if the pattern was longer
290        than about 50K.
291    
292    17. I have done a major re-factoring of the way pcre_compile() computes the
293        amount of memory needed for a compiled pattern. Previously, there was code
294        that made a preliminary scan of the pattern in order to do this. That was
295        OK when PCRE was new, but as the facilities have expanded, it has become
296        harder and harder to keep it in step with the real compile phase, and there
297        have been a number of bugs (see for example, 4 above). I have now found a
298        cunning way of running the real compile function in a "fake" mode that
299        enables it to compute how much memory it would need, while actually only
300        ever using a few hundred bytes of working memory and without too many
301        tests of the mode. This should make future maintenance and development
302        easier. A side effect of this work is that the limit of 200 on the nesting
303        depth of parentheses has been removed (though this was never a serious
304        limitation, I suspect). However, there is a downside: pcre_compile() now
305        runs more slowly than before (30% or more, depending on the pattern). I
306        hope this isn't a big issue. There is no effect on runtime performance.
307    
308    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
309        newline (only possible for the last line of a file) and it was a
310        pattern that set a locale (followed by /Lsomething), pcretest crashed.
311    
312    19. Added additional timing features to pcretest. (1) The -tm option now times
313        matching only, not compiling. (2) Both -t and -tm can be followed, as a
314        separate command line item, by a number that specifies the number of
315        repeats to use when timing. The default is 50000; this gives better
316        precision, but takes uncomfortably long for very large patterns.
317    
318    20. Extended pcre_study() to be more clever in cases where a branch of a
319        subpattern has no definite first character. For example, (a*|b*)[cd] would
320        previously give no result from pcre_study(). Now it recognizes that the
321        first character must be a, b, c, or d.
322    
323    21. There was an incorrect error "recursive call could loop indefinitely" if
324        a subpattern (or the entire pattern) that was being tested for matching an
325        empty string contained only one non-empty item after a nested subpattern.
326        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
327        incorrectly, because the \d was being skipped in the check.
328    
329    22. The pcretest program now has a new pattern option /B and a command line
330        option -b, which is equivalent to adding /B to every pattern. This causes
331        it to show the compiled bytecode, without the additional information that
332        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
333        is the same as /B/I).
334    
335    23. A new optimization is now able automatically to treat some sequences such
336        as a*b as a*+b. More specifically, if something simple (such as a character
337        or a simple class like \d) has an unlimited quantifier, and is followed by
338        something that cannot possibly match the quantified thing, the quantifier
339        is automatically "possessified".
340    
341    24. A recursive reference to a subpattern whose number was greater than 39
342        went wrong under certain circumstances in UTF-8 mode. This bug could also
343        have affected the operation of pcre_study().
344    
345    25. Realized that a little bit of performance could be had by replacing
346        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
347    
348    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
349    
350    27. Possessive quantifiers such as a++ were previously implemented by turning
351        them into atomic groups such as ($>a+). Now they have their own opcodes,
352        which improves performance. This includes the automatically created ones
353        from 23 above.
354    
355    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
356        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
357        the first matched character to be a colon. This applied both to named and
358        numbered groups.
359    
360    29. The ucpinternal.h header file was missing its idempotency #ifdef.
361    
362    30. I was sent a "project" file called libpcre.a.dev which I understand makes
363        building PCRE on Windows easier, so I have included it in the distribution.
364    
365    31. There is now a check in pcretest against a ridiculously large number being
366        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
367        loop, the loop is abandoned.
368    
369    32. Forward references to subpatterns in conditions such as (?(2)...) where
370        subpattern 2 is defined later cause pcre_compile() to search forwards in
371        the pattern for the relevant set of parentheses. This search went wrong
372        when there were unescaped parentheses in a character class, parentheses
373        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
374    
375    33. "Subroutine" calls and backreferences were previously restricted to
376        referencing subpatterns earlier in the regex. This restriction has now
377        been removed.
378    
379    34. Added a number of extra features that are going to be in Perl 5.10. On the
380        whole, these are just syntactic alternatives for features that PCRE had
381        previously implemented using the Python syntax or my own invention. The
382        other formats are all retained for compatibility.
383    
384        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
385            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
386            also .NET compatible.
387    
388        (b) A recursion or subroutine call to a named group can now be defined as
389            (?&name) as well as (?P>name).
390    
391        (c) A backreference to a named group can now be defined as \k<name> or
392            \k'name' as well as (?P=name). The new forms, as well as being in Perl
393            5.10, are also .NET compatible.
394    
395        (d) A conditional reference to a named group can now use the syntax
396            (?(<name>) or (?('name') as well as (?(name).
397    
398        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
399            groups (named and numbered) that are never evaluated inline, but can be
400            called as "subroutines" from elsewhere. In effect, the DEFINE condition
401            is always false. There may be only one alternative in such a group.
402    
403        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
404            as the simple (?(R). The condition is true only if the most recent
405            recursion is that of the given number or name. It does not search out
406            through the entire recursion stack.
407    
408        (g) The escape \gN or \g{N} has been added, where N is a positive or
409            negative number, specifying an absolute or relative reference.
410    
411    35. Tidied to get rid of some further signed/unsigned compiler warnings and
412        some "unreachable code" warnings.
413    
414    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
415        things, this adds five new scripts.
416    
417    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
418        There were also incompatibilities regarding the handling of \Q..\E inside
419        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
420        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
421    
422    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
423        matches an empty string, and forcibly breaks the loop. There were bugs in
424        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
425        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
426        separate and independent bugs (that affected different cases) have been
427        fixed.
428    
429    39. Refactored the code to abolish the use of different opcodes for small
430        capturing bracket numbers. This is a tidy that I avoided doing when I
431        removed the limit on the number of capturing brackets for 3.5 back in 2001.
432        The new approach is not only tidier, it makes it possible to reduce the
433        memory needed to fix the previous bug (38).
434    
435    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
436        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
437        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
438        mode.
439    
440    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
441        report.
442    
443    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
444        copy construction and assignment in the C++ wrapper.
445    
446    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
447        couple of bugs that could have given wrong results in the "--newline=crlf"
448        case.
449    
450    44. Added a number of casts and did some reorganization of signed/unsigned int
451        variables following suggestions from Dair Grant. Also renamed the variable
452        "this" as "item" because it is a C++ keyword.
453    
454    45. Arranged for dftables to add
455    
456          #include "pcre_internal.h"
457    
458        to pcre_chartables.c because without it, gcc 4.x may remove the array
459        definition from the final binary if PCRE is built into a static library and
460        dead code stripping is activated.
461    
462    46. For an unanchored pattern, if a match attempt fails at the start of a
463        newline sequence, and the newline setting is CRLF or ANY, and the next two
464        characters are CRLF, advance by two characters instead of one.
465    
466    
467    Version 6.7 04-Jul-06
468    ---------------------
469    
470     1. In order to handle tests when input lines are enormously long, pcretest has
471        been re-factored so that it automatically extends its buffers when
472        necessary. The code is crude, but this _is_ just a test program. The
473        default size has been increased from 32K to 50K.
474    
475     2. The code in pcre_study() was using the value of the re argument before
476        testing it for NULL. (Of course, in any sensible call of the function, it
477        won't be NULL.)
478    
479     3. The memmove() emulation function in pcre_internal.h, which is used on
480        systems that lack both memmove() and bcopy() - that is, hardly ever -
481        was missing a "static" storage class specifier.
482    
483     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
484        containing an extended class (one that cannot be represented by a bitmap
485        because it contains high-valued characters or Unicode property items, e.g.
486        [\pZ]). Almost always one would set UTF-8 mode when processing such a
487        pattern, but PCRE should not loop if you do not (it no longer does).
488        [Detail: two cases were found: (a) a repeated subpattern containing an
489        extended class; (b) a recursive reference to a subpattern that followed a
490        previous extended class. It wasn't skipping over the extended class
491        correctly when UTF-8 mode was not set.]
492    
493     5. A negated single-character class was not being recognized as fixed-length
494        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
495        compile error "lookbehind assertion is not fixed length".
496    
497     6. The RunPerlTest auxiliary script was showing an unexpected difference
498        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
499        write a Perl script that can interpret lines of an input file either as
500        byte characters or as UTF-8, which is what "perltest" was being required to
501        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
502        can't do is switch easily at run time between having the "use utf8;" pragma
503        or not. In the end, I fudged it by using the RunPerlTest script to insert
504        "use utf8;" explicitly for the UTF-8 tests.
505    
506     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
507        the end of the subject string, contrary to the documentation and to what
508        Perl does. This was true of both matching functions. Now it matches only at
509        the start of the subject and immediately after *internal* newlines.
510    
511     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
512        a pointer to an int instead of a pointer to an unsigned long int. This
513        caused problems on 64-bit systems.
514    
515     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
516        instance of the 'standard' template library not being so standard".
517    
518    10. There was no check on the number of named subpatterns nor the maximum
519        length of a subpattern name. The product of these values is used to compute
520        the size of the memory block for a compiled pattern. By supplying a very
521        long subpattern name and a large number of named subpatterns, the size
522        computation could be caused to overflow. This is now prevented by limiting
523        the length of names to 32 characters, and the number of named subpatterns
524        to 10,000.
525    
526    11. Subpatterns that are repeated with specific counts have to be replicated in
527        the compiled pattern. The size of memory for this was computed from the
528        length of the subpattern and the repeat count. The latter is limited to
529        65535, but there was no limit on the former, meaning that integer overflow
530        could in principle occur. The compiled length of a repeated subpattern is
531        now limited to 30,000 bytes in order to prevent this.
532    
533    12. Added the optional facility to have named substrings with the same name.
534    
535    13. Added the ability to use a named substring as a condition, using the
536        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
537        are numbers (not recommended). Forward references are permitted.
538    
539    14. Added forward references in named backreferences (if you see what I mean).
540    
541    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
542        pattern could run off the end of the subject. For example, the pattern
543        "(?s)(.{1,5})"8 did this with the subject "ab".
544    
545    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
546        PCRE_CASELESS was set when matching characters that were quantified with ?
547        or *.
548    
549    17. A character class other than a single negated character that had a minimum
550        but no maximum quantifier - for example [ab]{6,} - was not handled
551        correctly by pce_dfa_exec(). It would match only one character.
552    
553    18. A valid (though odd) pattern that looked like a POSIX character
554        class but used an invalid character after [ (for example [[,abc,]]) caused
555        pcre_compile() to give the error "Failed: internal error: code overflow" or
556        in some cases to crash with a glibc free() error. This could even happen if
557        the pattern terminated after [[ but there just happened to be a sequence of
558        letters, a binary zero, and a closing ] in the memory that followed.
559    
560    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
561        over the years. Originally (before any Unicode support), just the bottom 8
562        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
563        output from "man perlunicode" includes this:
564    
565          The regular expression compiler produces polymorphic opcodes.  That
566          is, the pattern adapts to the data and automatically switches to
567          the Unicode character scheme when presented with Unicode data--or
568          instead uses a traditional byte scheme when presented with byte
569          data.
570    
571        Sadly, a wide octal escape does not cause a switch, and in a string with
572        no other multibyte characters, these octal escapes are treated as before.
573        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
574        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
575        Unicode string.
576    
577        I have not perpetrated such confusion in PCRE. Up till now, it took just
578        the bottom 8 bits, as in old Perl. I have now made octal escapes with
579        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
580        translate to the appropriate multibyte character.
581    
582    29. Applied some refactoring to reduce the number of warnings from Microsoft
583        and Borland compilers. This has included removing the fudge introduced
584        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
585        a warning about an unused variable.
586    
587    21. PCRE has not included VT (character 0x0b) in the set of whitespace
588        characters since release 4.0, because Perl (from release 5.004) does not.
589        [Or at least, is documented not to: some releases seem to be in conflict
590        with the documentation.] However, when a pattern was studied with
591        pcre_study() and all its branches started with \s, PCRE still included VT
592        as a possible starting character. Of course, this did no harm; it just
593        caused an unnecessary match attempt.
594    
595    22. Removed a now-redundant internal flag bit that recorded the fact that case
596        dependency changed within the pattern. This was once needed for "required
597        byte" processing, but is no longer used. This recovers a now-scarce options
598        bit. Also moved the least significant internal flag bit to the most-
599        significant bit of the word, which was not previously used (hangover from
600        the days when it was an int rather than a uint) to free up another bit for
601        the future.
602    
603    23. Added support for CRLF line endings as well as CR and LF. As well as the
604        default being selectable at build time, it can now be changed at runtime
605        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
606        specify that it is scanning data with non-default line endings.
607    
608    24. Changed the definition of CXXLINK to make it agree with the definition of
609        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
610    
611    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
612        recursions. This makes a big different to stack usage for some patterns.
613    
614    26. If a subpattern containing a named recursion or subroutine reference such
615        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
616        the space required for the compiled pattern went wrong and gave too small a
617        value. Depending on the environment, this could lead to "Failed: internal
618        error: code overflow at offset 49" or "glibc detected double free or
619        corruption" errors.
620    
621    27. Applied patches from Google (a) to support the new newline modes and (b) to
622        advance over multibyte UTF-8 characters in GlobalReplace.
623    
624    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
625        difference for some implementation of PCRE in some Windows version.
626    
627    29. Added some extra testing facilities to pcretest:
628    
629        \q<number>   in a data line sets the "match limit" value
630        \Q<number>   in a data line sets the "match recursion limt" value
631        -S <number>  sets the stack size, where <number> is in megabytes
632    
633        The -S option isn't available for Windows.
634    
635    
636    Version 6.6 06-Feb-06
637    ---------------------
638    
639     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
640        in pcreposix.h. I have copied the definition from pcre.h.
641    
642     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
643        because pcre.h is no longer a built file.
644    
645     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
646        not normally included in the compiled code.
647    
648    
649  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
650  ---------------------  ---------------------
651    

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