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

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