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

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