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revision 87 by nigel, Sat Feb 24 21:41:21 2007 UTC revision 178 by ph10, Wed Jun 13 08:44:34 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.2 05-June-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        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
40    
41        (f) \g{name} is another synonym - part of Perl 5.10's unification of
42            reference syntax.
43    
44        (g) (?| introduces a group in which the numbering of parentheses in each
45            alternative starts with the same number.
46    
47        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
48    
49     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
50        PCRE_INFO_JCHANGED.
51    
52     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
53        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
54        for detecting groups that can match an empty string.
55    
56     9. A pattern with a very large number of alternatives (more than several
57        hundred) was running out of internal workspace during the pre-compile
58        phase, where pcre_compile() figures out how much memory will be needed. A
59        bit of new cunning has reduced the workspace needed for groups with
60        alternatives. The 1000-alternative test pattern now uses 12 bytes of
61        workspace instead of running out of the 4096 that are available.
62    
63    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
64    
65    
66    Version 7.1 24-Apr-07
67    ---------------------
68    
69     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
70        that is more "standard", making use of automake and other Autotools. There
71        is some re-arrangement of the files and adjustment of comments consequent
72        on this.
73    
74     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
75        for recursive directory scanning broke on some systems because the files
76        are not scanned in any specific order and on different systems the order
77        was different. A call to "sort" has been inserted into RunGrepTest for the
78        approprate test as a short-term fix. In the longer term there may be an
79        alternative.
80    
81     3. I had an email from Eric Raymond about problems translating some of PCRE's
82        man pages to HTML (despite the fact that I distribute HTML pages, some
83        people do their own conversions for various reasons). The problems
84        concerned the use of low-level troff macros .br and .in. I have therefore
85        removed all such uses from the man pages (some were redundant, some could
86        be replaced by .nf/.fi pairs). The 132html script that I use to generate
87        HTML has been updated to handle .nf/.fi and to complain if it encounters
88        .br or .in.
89    
90     4. Updated comments in configure.ac that get placed in config.h.in and also
91        arranged for config.h to be included in the distribution, with the name
92        config.h.generic, for the benefit of those who have to compile without
93        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
94    
95     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
96        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
97        makevp.bat for the current PCRE, using the additional files
98        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
99    
100     6. A Windows user reported a minor discrepancy with test 2, which turned out
101        to be caused by a trailing space on an input line that had got lost in his
102        copy. The trailing space was an accident, so I've just removed it.
103    
104     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
105        that is needed.
106    
107     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
108        as "const" (a) because they are and (b) because it helps the PHP
109        maintainers who have recently made a script to detect big data structures
110        in the php code that should be moved to the .rodata section. I remembered
111        to update Builducptable as well, so it won't revert if ucptable.h is ever
112        re-created.
113    
114     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
115        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
116        order to be able to cut out the UTF-8 tables in the latter when UTF-8
117        support is not required. This saves 1.5-2K of code, which is important in
118        some applications.
119    
120        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
121        so as not to refer to the tables, even though these functions will never be
122        called when UTF-8 support is disabled. Otherwise there are problems with a
123        shared library.
124    
125    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
126    
127        (a) It was defining its arguments as char * instead of void *.
128    
129        (b) It was assuming that all moves were upwards in memory; this was true
130            a long time ago when I wrote it, but is no longer the case.
131    
132        The emulated memove() is provided for those environments that have neither
133        memmove() nor bcopy(). I didn't think anyone used it these days, but that
134        is clearly not the case, as these two bugs were recently reported.
135    
136    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
137        and Detrail to create the HTML documentation, the .txt form of the man
138        pages, and it removes trailing spaces from listed files. It also creates
139        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
140        case, it wraps all the #defines with #ifndefs. This script should be run
141        before "make dist".
142    
143    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
144        with Unicode property support.
145    
146        (a) For a maximizing quantifier, if the two different cases of the
147            character were of different lengths in their UTF-8 codings (there are
148            some cases like this - I found 11), and the matching function had to
149            back up over a mixture of the two cases, it incorrectly assumed they
150            were both the same length.
151    
152        (b) When PCRE was configured to use the heap rather than the stack for
153            recursion during matching, it was not correctly preserving the data for
154            the other case of a UTF-8 character when checking ahead for a match
155            while processing a minimizing repeat. If the check also involved
156            matching a wide character, but failed, corruption could cause an
157            erroneous result when trying to check for a repeat of the original
158            character.
159    
160    13. Some tidying changes to the testing mechanism:
161    
162        (a) The RunTest script now detects the internal link size and whether there
163            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
164            values substituted by "configure". (The RunGrepTest script already did
165            this for UTF-8.) The configure.ac script no longer substitutes the
166            relevant variables.
167    
168        (b) The debugging options /B and /D in pcretest show the compiled bytecode
169            with length and offset values. This means that the output is different
170            for different internal link sizes. Test 2 is skipped for link sizes
171            other than 2 because of this, bypassing the problem. Unfortunately,
172            there was also a test in test 3 (the locale tests) that used /B and
173            failed for link sizes other than 2. Rather than cut the whole test out,
174            I have added a new /Z option to pcretest that replaces the length and
175            offset values with spaces. This is now used to make test 3 independent
176            of link size. (Test 2 will be tidied up later.)
177    
178    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
179        segmentation fault instead of returning the appropriate error message.
180    
181    15. In multiline mode when the newline sequence was set to "any", the pattern
182        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
183        This doesn't seem right; it now treats the CRLF combination as the line
184        ending, and so does not match in that case. It's only a pattern such as ^$
185        that would hit this one: something like ^ABC$ would have failed after \r
186        and then tried again after \r\n.
187    
188    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
189        in an attempt to make files that differ only in their line terminators
190        compare equal. This works on Linux.
191    
192    17. Under certain error circumstances pcregrep might try to free random memory
193        as it exited. This is now fixed, thanks to valgrind.
194    
195    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
196        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
197        was because its rules for how to advance for /g after matching an empty
198        string at the end of a line did not allow for this case. They now check for
199        it specially.
200    
201    20. pcretest is supposed to handle patterns and data of any length, by
202        extending its buffers when necessary. It was getting this wrong when the
203        buffer for a data line had to be extended.
204    
205    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
206        CRLF as a newline sequence.
207    
208    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
209        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
210        I have nevertheless tidied it up.
211    
212    23. Added some casts to kill warnings from HP-UX ia64 compiler.
213    
214    24. Added a man page for pcre-config.
215    
216    
217    Version 7.0 19-Dec-06
218    ---------------------
219    
220     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
221        moving to gcc 4.1.1.
222    
223     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
224        sys/time.h, which is documented as needed for this function. It doesn't
225        seem to matter on Linux, but it showed up on some releases of OS X.
226    
227     3. It seems that there are systems where bytes whose values are greater than
228        127 match isprint() in the "C" locale. The "C" locale should be the
229        default when a C program starts up. In most systems, only ASCII printing
230        characters match isprint(). This difference caused the output from pcretest
231        to vary, making some of the tests fail. I have changed pcretest so that:
232    
233        (a) When it is outputting text in the compiled version of a pattern, bytes
234            other than 32-126 are always shown as hex escapes.
235    
236        (b) When it is outputting text that is a matched part of a subject string,
237            it does the same, unless a different locale has been set for the match
238            (using the /L modifier). In this case, it uses isprint() to decide.
239    
240     4. Fixed a major bug that caused incorrect computation of the amount of memory
241        required for a compiled pattern when options that changed within the
242        pattern affected the logic of the preliminary scan that determines the
243        length. The relevant options are -x, and -i in UTF-8 mode. The result was
244        that the computed length was too small. The symptoms of this bug were
245        either the PCRE error "internal error: code overflow" from pcre_compile(),
246        or a glibc crash with a message such as "pcretest: free(): invalid next
247        size (fast)". Examples of patterns that provoked this bug (shown in
248        pcretest format) are:
249    
250          /(?-x: )/x
251          /(?x)(?-x: \s*#\s*)/
252          /((?i)[\x{c0}])/8
253          /(?i:[\x{c0}])/8
254    
255        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
256        is now done differently.
257    
258     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
259        wrapper classes; (b) implement a new function in the C++ scanner that is
260        more efficient than the old way of doing things because it avoids levels of
261        recursion in the regex matching; (c) add a paragraph to the documentation
262        for the FullMatch() function.
263    
264     6. The escape sequence \n was being treated as whatever was defined as
265        "newline". Not only was this contrary to the documentation, which states
266        that \n is character 10 (hex 0A), but it also went horribly wrong when
267        "newline" was defined as CRLF. This has been fixed.
268    
269     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
270        was being set to -1 for the "end of line" case (supposedly a value that no
271        character can have). Though this value is never used (the check for end of
272        line is "zero bytes in current character"), it caused compiler complaints.
273        I've changed it to 0xffffffff.
274    
275     8. In pcre_version.c, the version string was being built by a sequence of
276        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
277        string (as it is for production releases) called a macro with an empty
278        argument. The C standard says the result of this is undefined. The gcc
279        compiler treats it as an empty string (which was what was wanted) but it is
280        reported that Visual C gives an error. The source has been hacked around to
281        avoid this problem.
282    
283     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
284        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
285        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
286        of them did).
287    
288    10. Originally, pcretest opened its input and output without "b"; then I was
289        told that "b" was needed in some environments, so it was added for release
290        5.0 to both the input and output. (It makes no difference on Unix-like
291        systems.) Later I was told that it is wrong for the input on Windows. I've
292        now abstracted the modes into two macros, to make it easier to fiddle with
293        them, and removed "b" from the input mode under Windows.
294    
295    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
296    
297    12. Added -help and --help to pcretest as an official way of being reminded
298        of the options.
299    
300    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
301        and pcrecpp.cc because they annoy compilers at high warning levels.
302    
303    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
304    
305    15. Fixed an occurrence of == in configure.ac that should have been = (shell
306        scripts are not C programs :-) and which was not noticed because it works
307        on Linux.
308    
309    16. pcretest is supposed to handle any length of pattern and data line (as one
310        line or as a continued sequence of lines) by extending its input buffer if
311        necessary. This feature was broken for very long pattern lines, leading to
312        a string of junk being passed to pcre_compile() if the pattern was longer
313        than about 50K.
314    
315    17. I have done a major re-factoring of the way pcre_compile() computes the
316        amount of memory needed for a compiled pattern. Previously, there was code
317        that made a preliminary scan of the pattern in order to do this. That was
318        OK when PCRE was new, but as the facilities have expanded, it has become
319        harder and harder to keep it in step with the real compile phase, and there
320        have been a number of bugs (see for example, 4 above). I have now found a
321        cunning way of running the real compile function in a "fake" mode that
322        enables it to compute how much memory it would need, while actually only
323        ever using a few hundred bytes of working memory and without too many
324        tests of the mode. This should make future maintenance and development
325        easier. A side effect of this work is that the limit of 200 on the nesting
326        depth of parentheses has been removed (though this was never a serious
327        limitation, I suspect). However, there is a downside: pcre_compile() now
328        runs more slowly than before (30% or more, depending on the pattern). I
329        hope this isn't a big issue. There is no effect on runtime performance.
330    
331    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
332        newline (only possible for the last line of a file) and it was a
333        pattern that set a locale (followed by /Lsomething), pcretest crashed.
334    
335    19. Added additional timing features to pcretest. (1) The -tm option now times
336        matching only, not compiling. (2) Both -t and -tm can be followed, as a
337        separate command line item, by a number that specifies the number of
338        repeats to use when timing. The default is 50000; this gives better
339        precision, but takes uncomfortably long for very large patterns.
340    
341    20. Extended pcre_study() to be more clever in cases where a branch of a
342        subpattern has no definite first character. For example, (a*|b*)[cd] would
343        previously give no result from pcre_study(). Now it recognizes that the
344        first character must be a, b, c, or d.
345    
346    21. There was an incorrect error "recursive call could loop indefinitely" if
347        a subpattern (or the entire pattern) that was being tested for matching an
348        empty string contained only one non-empty item after a nested subpattern.
349        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
350        incorrectly, because the \d was being skipped in the check.
351    
352    22. The pcretest program now has a new pattern option /B and a command line
353        option -b, which is equivalent to adding /B to every pattern. This causes
354        it to show the compiled bytecode, without the additional information that
355        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
356        is the same as /B/I).
357    
358    23. A new optimization is now able automatically to treat some sequences such
359        as a*b as a*+b. More specifically, if something simple (such as a character
360        or a simple class like \d) has an unlimited quantifier, and is followed by
361        something that cannot possibly match the quantified thing, the quantifier
362        is automatically "possessified".
363    
364    24. A recursive reference to a subpattern whose number was greater than 39
365        went wrong under certain circumstances in UTF-8 mode. This bug could also
366        have affected the operation of pcre_study().
367    
368    25. Realized that a little bit of performance could be had by replacing
369        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
370    
371    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
372    
373    27. Possessive quantifiers such as a++ were previously implemented by turning
374        them into atomic groups such as ($>a+). Now they have their own opcodes,
375        which improves performance. This includes the automatically created ones
376        from 23 above.
377    
378    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
379        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
380        the first matched character to be a colon. This applied both to named and
381        numbered groups.
382    
383    29. The ucpinternal.h header file was missing its idempotency #ifdef.
384    
385    30. I was sent a "project" file called libpcre.a.dev which I understand makes
386        building PCRE on Windows easier, so I have included it in the distribution.
387    
388    31. There is now a check in pcretest against a ridiculously large number being
389        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
390        loop, the loop is abandoned.
391    
392    32. Forward references to subpatterns in conditions such as (?(2)...) where
393        subpattern 2 is defined later cause pcre_compile() to search forwards in
394        the pattern for the relevant set of parentheses. This search went wrong
395        when there were unescaped parentheses in a character class, parentheses
396        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
397    
398    33. "Subroutine" calls and backreferences were previously restricted to
399        referencing subpatterns earlier in the regex. This restriction has now
400        been removed.
401    
402    34. Added a number of extra features that are going to be in Perl 5.10. On the
403        whole, these are just syntactic alternatives for features that PCRE had
404        previously implemented using the Python syntax or my own invention. The
405        other formats are all retained for compatibility.
406    
407        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
408            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
409            also .NET compatible.
410    
411        (b) A recursion or subroutine call to a named group can now be defined as
412            (?&name) as well as (?P>name).
413    
414        (c) A backreference to a named group can now be defined as \k<name> or
415            \k'name' as well as (?P=name). The new forms, as well as being in Perl
416            5.10, are also .NET compatible.
417    
418        (d) A conditional reference to a named group can now use the syntax
419            (?(<name>) or (?('name') as well as (?(name).
420    
421        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
422            groups (named and numbered) that are never evaluated inline, but can be
423            called as "subroutines" from elsewhere. In effect, the DEFINE condition
424            is always false. There may be only one alternative in such a group.
425    
426        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
427            as the simple (?(R). The condition is true only if the most recent
428            recursion is that of the given number or name. It does not search out
429            through the entire recursion stack.
430    
431        (g) The escape \gN or \g{N} has been added, where N is a positive or
432            negative number, specifying an absolute or relative reference.
433    
434    35. Tidied to get rid of some further signed/unsigned compiler warnings and
435        some "unreachable code" warnings.
436    
437    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
438        things, this adds five new scripts.
439    
440    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
441        There were also incompatibilities regarding the handling of \Q..\E inside
442        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
443        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
444    
445    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
446        matches an empty string, and forcibly breaks the loop. There were bugs in
447        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
448        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
449        separate and independent bugs (that affected different cases) have been
450        fixed.
451    
452    39. Refactored the code to abolish the use of different opcodes for small
453        capturing bracket numbers. This is a tidy that I avoided doing when I
454        removed the limit on the number of capturing brackets for 3.5 back in 2001.
455        The new approach is not only tidier, it makes it possible to reduce the
456        memory needed to fix the previous bug (38).
457    
458    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
459        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
460        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
461        mode.
462    
463    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
464        report.
465    
466    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
467        copy construction and assignment in the C++ wrapper.
468    
469    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
470        couple of bugs that could have given wrong results in the "--newline=crlf"
471        case.
472    
473    44. Added a number of casts and did some reorganization of signed/unsigned int
474        variables following suggestions from Dair Grant. Also renamed the variable
475        "this" as "item" because it is a C++ keyword.
476    
477    45. Arranged for dftables to add
478    
479          #include "pcre_internal.h"
480    
481        to pcre_chartables.c because without it, gcc 4.x may remove the array
482        definition from the final binary if PCRE is built into a static library and
483        dead code stripping is activated.
484    
485    46. For an unanchored pattern, if a match attempt fails at the start of a
486        newline sequence, and the newline setting is CRLF or ANY, and the next two
487        characters are CRLF, advance by two characters instead of one.
488    
489    
490    Version 6.7 04-Jul-06
491    ---------------------
492    
493     1. In order to handle tests when input lines are enormously long, pcretest has
494        been re-factored so that it automatically extends its buffers when
495        necessary. The code is crude, but this _is_ just a test program. The
496        default size has been increased from 32K to 50K.
497    
498     2. The code in pcre_study() was using the value of the re argument before
499        testing it for NULL. (Of course, in any sensible call of the function, it
500        won't be NULL.)
501    
502     3. The memmove() emulation function in pcre_internal.h, which is used on
503        systems that lack both memmove() and bcopy() - that is, hardly ever -
504        was missing a "static" storage class specifier.
505    
506     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
507        containing an extended class (one that cannot be represented by a bitmap
508        because it contains high-valued characters or Unicode property items, e.g.
509        [\pZ]). Almost always one would set UTF-8 mode when processing such a
510        pattern, but PCRE should not loop if you do not (it no longer does).
511        [Detail: two cases were found: (a) a repeated subpattern containing an
512        extended class; (b) a recursive reference to a subpattern that followed a
513        previous extended class. It wasn't skipping over the extended class
514        correctly when UTF-8 mode was not set.]
515    
516     5. A negated single-character class was not being recognized as fixed-length
517        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
518        compile error "lookbehind assertion is not fixed length".
519    
520     6. The RunPerlTest auxiliary script was showing an unexpected difference
521        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
522        write a Perl script that can interpret lines of an input file either as
523        byte characters or as UTF-8, which is what "perltest" was being required to
524        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
525        can't do is switch easily at run time between having the "use utf8;" pragma
526        or not. In the end, I fudged it by using the RunPerlTest script to insert
527        "use utf8;" explicitly for the UTF-8 tests.
528    
529     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
530        the end of the subject string, contrary to the documentation and to what
531        Perl does. This was true of both matching functions. Now it matches only at
532        the start of the subject and immediately after *internal* newlines.
533    
534     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
535        a pointer to an int instead of a pointer to an unsigned long int. This
536        caused problems on 64-bit systems.
537    
538     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
539        instance of the 'standard' template library not being so standard".
540    
541    10. There was no check on the number of named subpatterns nor the maximum
542        length of a subpattern name. The product of these values is used to compute
543        the size of the memory block for a compiled pattern. By supplying a very
544        long subpattern name and a large number of named subpatterns, the size
545        computation could be caused to overflow. This is now prevented by limiting
546        the length of names to 32 characters, and the number of named subpatterns
547        to 10,000.
548    
549    11. Subpatterns that are repeated with specific counts have to be replicated in
550        the compiled pattern. The size of memory for this was computed from the
551        length of the subpattern and the repeat count. The latter is limited to
552        65535, but there was no limit on the former, meaning that integer overflow
553        could in principle occur. The compiled length of a repeated subpattern is
554        now limited to 30,000 bytes in order to prevent this.
555    
556    12. Added the optional facility to have named substrings with the same name.
557    
558    13. Added the ability to use a named substring as a condition, using the
559        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
560        are numbers (not recommended). Forward references are permitted.
561    
562    14. Added forward references in named backreferences (if you see what I mean).
563    
564    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
565        pattern could run off the end of the subject. For example, the pattern
566        "(?s)(.{1,5})"8 did this with the subject "ab".
567    
568    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
569        PCRE_CASELESS was set when matching characters that were quantified with ?
570        or *.
571    
572    17. A character class other than a single negated character that had a minimum
573        but no maximum quantifier - for example [ab]{6,} - was not handled
574        correctly by pce_dfa_exec(). It would match only one character.
575    
576    18. A valid (though odd) pattern that looked like a POSIX character
577        class but used an invalid character after [ (for example [[,abc,]]) caused
578        pcre_compile() to give the error "Failed: internal error: code overflow" or
579        in some cases to crash with a glibc free() error. This could even happen if
580        the pattern terminated after [[ but there just happened to be a sequence of
581        letters, a binary zero, and a closing ] in the memory that followed.
582    
583    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
584        over the years. Originally (before any Unicode support), just the bottom 8
585        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
586        output from "man perlunicode" includes this:
587    
588          The regular expression compiler produces polymorphic opcodes.  That
589          is, the pattern adapts to the data and automatically switches to
590          the Unicode character scheme when presented with Unicode data--or
591          instead uses a traditional byte scheme when presented with byte
592          data.
593    
594        Sadly, a wide octal escape does not cause a switch, and in a string with
595        no other multibyte characters, these octal escapes are treated as before.
596        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
597        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
598        Unicode string.
599    
600        I have not perpetrated such confusion in PCRE. Up till now, it took just
601        the bottom 8 bits, as in old Perl. I have now made octal escapes with
602        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
603        translate to the appropriate multibyte character.
604    
605    29. Applied some refactoring to reduce the number of warnings from Microsoft
606        and Borland compilers. This has included removing the fudge introduced
607        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
608        a warning about an unused variable.
609    
610    21. PCRE has not included VT (character 0x0b) in the set of whitespace
611        characters since release 4.0, because Perl (from release 5.004) does not.
612        [Or at least, is documented not to: some releases seem to be in conflict
613        with the documentation.] However, when a pattern was studied with
614        pcre_study() and all its branches started with \s, PCRE still included VT
615        as a possible starting character. Of course, this did no harm; it just
616        caused an unnecessary match attempt.
617    
618    22. Removed a now-redundant internal flag bit that recorded the fact that case
619        dependency changed within the pattern. This was once needed for "required
620        byte" processing, but is no longer used. This recovers a now-scarce options
621        bit. Also moved the least significant internal flag bit to the most-
622        significant bit of the word, which was not previously used (hangover from
623        the days when it was an int rather than a uint) to free up another bit for
624        the future.
625    
626    23. Added support for CRLF line endings as well as CR and LF. As well as the
627        default being selectable at build time, it can now be changed at runtime
628        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
629        specify that it is scanning data with non-default line endings.
630    
631    24. Changed the definition of CXXLINK to make it agree with the definition of
632        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
633    
634    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
635        recursions. This makes a big different to stack usage for some patterns.
636    
637    26. If a subpattern containing a named recursion or subroutine reference such
638        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
639        the space required for the compiled pattern went wrong and gave too small a
640        value. Depending on the environment, this could lead to "Failed: internal
641        error: code overflow at offset 49" or "glibc detected double free or
642        corruption" errors.
643    
644    27. Applied patches from Google (a) to support the new newline modes and (b) to
645        advance over multibyte UTF-8 characters in GlobalReplace.
646    
647    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
648        difference for some implementation of PCRE in some Windows version.
649    
650    29. Added some extra testing facilities to pcretest:
651    
652        \q<number>   in a data line sets the "match limit" value
653        \Q<number>   in a data line sets the "match recursion limt" value
654        -S <number>  sets the stack size, where <number> is in megabytes
655    
656        The -S option isn't available for Windows.
657    
658    
659    Version 6.6 06-Feb-06
660    ---------------------
661    
662     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
663        in pcreposix.h. I have copied the definition from pcre.h.
664    
665     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
666        because pcre.h is no longer a built file.
667    
668     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
669        not normally included in the compiled code.
670    
671    
672  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
673  ---------------------  ---------------------
674    

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