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revision 87 by nigel, Sat Feb 24 21:41:21 2007 UTC revision 205 by ph10, Fri Aug 3 13:18:33 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.3 05-Jul-07
5    ---------------------
6    
7     1. In the rejigging of the build system that eventually resulted in 7.1, the
8        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
9        brackets there is not right, since it causes compilers to look for an
10        installed pcre.h, not the version that is in the source that is being
11        compiled (which of course may be different). I have changed it back to:
12    
13          #include "pcre.h"
14    
15        I have a vague recollection that the change was concerned with compiling in
16        different directories, but in the new build system, that is taken care of
17        by the VPATH setting the Makefile.
18    
19     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
20        when the subject happened to end in the byte 0x85 (e.g. if the last
21        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
22        characters but of course it shouldn't be taken as a newline when it is part
23        of another character. The bug was that, for an unlimited repeat of . in
24        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
25        characters when looking for a newline.
26    
27     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
28    
29     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
30        in debug output.
31    
32     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
33        long printing in the pcrecpp unittest when running under MinGW.
34    
35     6. ESC_K was left out of the EBCDIC table.
36    
37     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
38        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
39        limit also applies to "virtual nesting" when a pattern is recursive, and in
40        this case 1000 isn't so big. I have been able to remove this limit at the
41        expense of backing off one optimization in certain circumstances. Normally,
42        when pcre_exec() would call its internal match() function recursively and
43        immediately return the result unconditionally, it uses a "tail recursion"
44        feature to save stack. However, when a subpattern that can match an empty
45        string has an unlimited repetition quantifier, it no longer makes this
46        optimization. That gives it a stack frame in which to save the data for
47        checking that an empty string has been matched. Previously this was taken
48        from the 1000-entry workspace that had been reserved. So now there is no
49        explicit limit, but more stack is used.
50    
51     8. Applied Daniel's patches to solve problems with the import/export magic
52        syntax that is required for Windows, and which was going wrong for the
53        pcreposix and pcrecpp parts of the library. These were overlooked when this
54        problem was solved for the main library.
55    
56     9. There were some crude static tests to avoid integer overflow when computing
57        the size of patterns that contain repeated groups with explicit upper
58        limits. As the maximum quantifier is 65535, the maximum group length was
59        set at 30,000 so that the product of these two numbers did not overflow a
60        32-bit integer. However, it turns out that people want to use groups that
61        are longer than 30,000 bytes (though not repeat them that many times).
62        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
63        made it possible to implement the integer overflow checks in a much more
64        dynamic way, which I have now done. The artificial limitation on group
65        length has been removed - we now have only the limit on the total length of
66        the compiled pattern, which depends on the LINK_SIZE setting.
67    
68    10. Fixed a bug in the documentation for get/copy named substring when
69        duplicate names are permitted. If none of the named substrings are set, the
70        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
71        empty string.
72    
73    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
74        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
75        because the ] is interpreted as the first data character and the
76        terminating ] is not found. PCRE has been made compatible with Perl in this
77        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
78        cause memory overwriting.
79    
80    
81    Version 7.2 19-Jun-07
82    ---------------------
83    
84     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
85        which is apparently normally available under Windows.
86    
87     2. Re-jig the pcregrep tests with different newline settings in an attempt
88        to make them independent of the local environment's newline setting.
89    
90     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
91    
92     4. Some of the "internals" tests were previously cut out when the link size
93        was not 2, because the output contained actual offsets. The recent new
94        "Z" feature of pcretest means that these can be cut out, making the tests
95        usable with all link sizes.
96    
97     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
98        stack recursion. This gives a massive performance boost under BSD, but just
99        a small improvement under Linux. However, it saves one field in the frame
100        in all cases.
101    
102     6. Added more features from the forthcoming Perl 5.10:
103    
104        (a) (?-n) (where n is a string of digits) is a relative subroutine or
105            recursion call. It refers to the nth most recently opened parentheses.
106    
107        (b) (?+n) is also a relative subroutine call; it refers to the nth next
108            to be opened parentheses.
109    
110        (c) Conditions that refer to capturing parentheses can be specified
111            relatively, for example, (?(-2)... or (?(+3)...
112    
113        (d) \K resets the start of the current match so that everything before
114            is not part of it.
115    
116        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
117    
118        (f) \g{name} is another synonym - part of Perl 5.10's unification of
119            reference syntax.
120    
121        (g) (?| introduces a group in which the numbering of parentheses in each
122            alternative starts with the same number.
123    
124        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
125    
126     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
127        PCRE_INFO_JCHANGED.
128    
129     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
130        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
131        for detecting groups that can match an empty string.
132    
133     9. A pattern with a very large number of alternatives (more than several
134        hundred) was running out of internal workspace during the pre-compile
135        phase, where pcre_compile() figures out how much memory will be needed. A
136        bit of new cunning has reduced the workspace needed for groups with
137        alternatives. The 1000-alternative test pattern now uses 12 bytes of
138        workspace instead of running out of the 4096 that are available.
139    
140    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
141    
142    11. Applied patch from Google to remove an optimization that didn't quite work.
143        The report of the bug said:
144    
145          pcrecpp::RE("a*").FullMatch("aaa") matches, while
146          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
147          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
148    
149    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
150        it matched the wrong number of bytes.
151    
152    
153    Version 7.1 24-Apr-07
154    ---------------------
155    
156     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
157        that is more "standard", making use of automake and other Autotools. There
158        is some re-arrangement of the files and adjustment of comments consequent
159        on this.
160    
161     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
162        for recursive directory scanning broke on some systems because the files
163        are not scanned in any specific order and on different systems the order
164        was different. A call to "sort" has been inserted into RunGrepTest for the
165        approprate test as a short-term fix. In the longer term there may be an
166        alternative.
167    
168     3. I had an email from Eric Raymond about problems translating some of PCRE's
169        man pages to HTML (despite the fact that I distribute HTML pages, some
170        people do their own conversions for various reasons). The problems
171        concerned the use of low-level troff macros .br and .in. I have therefore
172        removed all such uses from the man pages (some were redundant, some could
173        be replaced by .nf/.fi pairs). The 132html script that I use to generate
174        HTML has been updated to handle .nf/.fi and to complain if it encounters
175        .br or .in.
176    
177     4. Updated comments in configure.ac that get placed in config.h.in and also
178        arranged for config.h to be included in the distribution, with the name
179        config.h.generic, for the benefit of those who have to compile without
180        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
181    
182     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
183        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
184        makevp.bat for the current PCRE, using the additional files
185        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
186    
187     6. A Windows user reported a minor discrepancy with test 2, which turned out
188        to be caused by a trailing space on an input line that had got lost in his
189        copy. The trailing space was an accident, so I've just removed it.
190    
191     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
192        that is needed.
193    
194     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
195        as "const" (a) because they are and (b) because it helps the PHP
196        maintainers who have recently made a script to detect big data structures
197        in the php code that should be moved to the .rodata section. I remembered
198        to update Builducptable as well, so it won't revert if ucptable.h is ever
199        re-created.
200    
201     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
202        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
203        order to be able to cut out the UTF-8 tables in the latter when UTF-8
204        support is not required. This saves 1.5-2K of code, which is important in
205        some applications.
206    
207        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
208        so as not to refer to the tables, even though these functions will never be
209        called when UTF-8 support is disabled. Otherwise there are problems with a
210        shared library.
211    
212    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
213    
214        (a) It was defining its arguments as char * instead of void *.
215    
216        (b) It was assuming that all moves were upwards in memory; this was true
217            a long time ago when I wrote it, but is no longer the case.
218    
219        The emulated memove() is provided for those environments that have neither
220        memmove() nor bcopy(). I didn't think anyone used it these days, but that
221        is clearly not the case, as these two bugs were recently reported.
222    
223    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
224        and Detrail to create the HTML documentation, the .txt form of the man
225        pages, and it removes trailing spaces from listed files. It also creates
226        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
227        case, it wraps all the #defines with #ifndefs. This script should be run
228        before "make dist".
229    
230    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
231        with Unicode property support.
232    
233        (a) For a maximizing quantifier, if the two different cases of the
234            character were of different lengths in their UTF-8 codings (there are
235            some cases like this - I found 11), and the matching function had to
236            back up over a mixture of the two cases, it incorrectly assumed they
237            were both the same length.
238    
239        (b) When PCRE was configured to use the heap rather than the stack for
240            recursion during matching, it was not correctly preserving the data for
241            the other case of a UTF-8 character when checking ahead for a match
242            while processing a minimizing repeat. If the check also involved
243            matching a wide character, but failed, corruption could cause an
244            erroneous result when trying to check for a repeat of the original
245            character.
246    
247    13. Some tidying changes to the testing mechanism:
248    
249        (a) The RunTest script now detects the internal link size and whether there
250            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
251            values substituted by "configure". (The RunGrepTest script already did
252            this for UTF-8.) The configure.ac script no longer substitutes the
253            relevant variables.
254    
255        (b) The debugging options /B and /D in pcretest show the compiled bytecode
256            with length and offset values. This means that the output is different
257            for different internal link sizes. Test 2 is skipped for link sizes
258            other than 2 because of this, bypassing the problem. Unfortunately,
259            there was also a test in test 3 (the locale tests) that used /B and
260            failed for link sizes other than 2. Rather than cut the whole test out,
261            I have added a new /Z option to pcretest that replaces the length and
262            offset values with spaces. This is now used to make test 3 independent
263            of link size. (Test 2 will be tidied up later.)
264    
265    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
266        segmentation fault instead of returning the appropriate error message.
267    
268    15. In multiline mode when the newline sequence was set to "any", the pattern
269        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
270        This doesn't seem right; it now treats the CRLF combination as the line
271        ending, and so does not match in that case. It's only a pattern such as ^$
272        that would hit this one: something like ^ABC$ would have failed after \r
273        and then tried again after \r\n.
274    
275    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
276        in an attempt to make files that differ only in their line terminators
277        compare equal. This works on Linux.
278    
279    17. Under certain error circumstances pcregrep might try to free random memory
280        as it exited. This is now fixed, thanks to valgrind.
281    
282    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
283        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
284        was because its rules for how to advance for /g after matching an empty
285        string at the end of a line did not allow for this case. They now check for
286        it specially.
287    
288    20. pcretest is supposed to handle patterns and data of any length, by
289        extending its buffers when necessary. It was getting this wrong when the
290        buffer for a data line had to be extended.
291    
292    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
293        CRLF as a newline sequence.
294    
295    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
296        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
297        I have nevertheless tidied it up.
298    
299    23. Added some casts to kill warnings from HP-UX ia64 compiler.
300    
301    24. Added a man page for pcre-config.
302    
303    
304    Version 7.0 19-Dec-06
305    ---------------------
306    
307     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
308        moving to gcc 4.1.1.
309    
310     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
311        sys/time.h, which is documented as needed for this function. It doesn't
312        seem to matter on Linux, but it showed up on some releases of OS X.
313    
314     3. It seems that there are systems where bytes whose values are greater than
315        127 match isprint() in the "C" locale. The "C" locale should be the
316        default when a C program starts up. In most systems, only ASCII printing
317        characters match isprint(). This difference caused the output from pcretest
318        to vary, making some of the tests fail. I have changed pcretest so that:
319    
320        (a) When it is outputting text in the compiled version of a pattern, bytes
321            other than 32-126 are always shown as hex escapes.
322    
323        (b) When it is outputting text that is a matched part of a subject string,
324            it does the same, unless a different locale has been set for the match
325            (using the /L modifier). In this case, it uses isprint() to decide.
326    
327     4. Fixed a major bug that caused incorrect computation of the amount of memory
328        required for a compiled pattern when options that changed within the
329        pattern affected the logic of the preliminary scan that determines the
330        length. The relevant options are -x, and -i in UTF-8 mode. The result was
331        that the computed length was too small. The symptoms of this bug were
332        either the PCRE error "internal error: code overflow" from pcre_compile(),
333        or a glibc crash with a message such as "pcretest: free(): invalid next
334        size (fast)". Examples of patterns that provoked this bug (shown in
335        pcretest format) are:
336    
337          /(?-x: )/x
338          /(?x)(?-x: \s*#\s*)/
339          /((?i)[\x{c0}])/8
340          /(?i:[\x{c0}])/8
341    
342        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
343        is now done differently.
344    
345     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
346        wrapper classes; (b) implement a new function in the C++ scanner that is
347        more efficient than the old way of doing things because it avoids levels of
348        recursion in the regex matching; (c) add a paragraph to the documentation
349        for the FullMatch() function.
350    
351     6. The escape sequence \n was being treated as whatever was defined as
352        "newline". Not only was this contrary to the documentation, which states
353        that \n is character 10 (hex 0A), but it also went horribly wrong when
354        "newline" was defined as CRLF. This has been fixed.
355    
356     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
357        was being set to -1 for the "end of line" case (supposedly a value that no
358        character can have). Though this value is never used (the check for end of
359        line is "zero bytes in current character"), it caused compiler complaints.
360        I've changed it to 0xffffffff.
361    
362     8. In pcre_version.c, the version string was being built by a sequence of
363        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
364        string (as it is for production releases) called a macro with an empty
365        argument. The C standard says the result of this is undefined. The gcc
366        compiler treats it as an empty string (which was what was wanted) but it is
367        reported that Visual C gives an error. The source has been hacked around to
368        avoid this problem.
369    
370     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
371        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
372        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
373        of them did).
374    
375    10. Originally, pcretest opened its input and output without "b"; then I was
376        told that "b" was needed in some environments, so it was added for release
377        5.0 to both the input and output. (It makes no difference on Unix-like
378        systems.) Later I was told that it is wrong for the input on Windows. I've
379        now abstracted the modes into two macros, to make it easier to fiddle with
380        them, and removed "b" from the input mode under Windows.
381    
382    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
383    
384    12. Added -help and --help to pcretest as an official way of being reminded
385        of the options.
386    
387    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
388        and pcrecpp.cc because they annoy compilers at high warning levels.
389    
390    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
391    
392    15. Fixed an occurrence of == in configure.ac that should have been = (shell
393        scripts are not C programs :-) and which was not noticed because it works
394        on Linux.
395    
396    16. pcretest is supposed to handle any length of pattern and data line (as one
397        line or as a continued sequence of lines) by extending its input buffer if
398        necessary. This feature was broken for very long pattern lines, leading to
399        a string of junk being passed to pcre_compile() if the pattern was longer
400        than about 50K.
401    
402    17. I have done a major re-factoring of the way pcre_compile() computes the
403        amount of memory needed for a compiled pattern. Previously, there was code
404        that made a preliminary scan of the pattern in order to do this. That was
405        OK when PCRE was new, but as the facilities have expanded, it has become
406        harder and harder to keep it in step with the real compile phase, and there
407        have been a number of bugs (see for example, 4 above). I have now found a
408        cunning way of running the real compile function in a "fake" mode that
409        enables it to compute how much memory it would need, while actually only
410        ever using a few hundred bytes of working memory and without too many
411        tests of the mode. This should make future maintenance and development
412        easier. A side effect of this work is that the limit of 200 on the nesting
413        depth of parentheses has been removed (though this was never a serious
414        limitation, I suspect). However, there is a downside: pcre_compile() now
415        runs more slowly than before (30% or more, depending on the pattern). I
416        hope this isn't a big issue. There is no effect on runtime performance.
417    
418    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
419        newline (only possible for the last line of a file) and it was a
420        pattern that set a locale (followed by /Lsomething), pcretest crashed.
421    
422    19. Added additional timing features to pcretest. (1) The -tm option now times
423        matching only, not compiling. (2) Both -t and -tm can be followed, as a
424        separate command line item, by a number that specifies the number of
425        repeats to use when timing. The default is 50000; this gives better
426        precision, but takes uncomfortably long for very large patterns.
427    
428    20. Extended pcre_study() to be more clever in cases where a branch of a
429        subpattern has no definite first character. For example, (a*|b*)[cd] would
430        previously give no result from pcre_study(). Now it recognizes that the
431        first character must be a, b, c, or d.
432    
433    21. There was an incorrect error "recursive call could loop indefinitely" if
434        a subpattern (or the entire pattern) that was being tested for matching an
435        empty string contained only one non-empty item after a nested subpattern.
436        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
437        incorrectly, because the \d was being skipped in the check.
438    
439    22. The pcretest program now has a new pattern option /B and a command line
440        option -b, which is equivalent to adding /B to every pattern. This causes
441        it to show the compiled bytecode, without the additional information that
442        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
443        is the same as /B/I).
444    
445    23. A new optimization is now able automatically to treat some sequences such
446        as a*b as a*+b. More specifically, if something simple (such as a character
447        or a simple class like \d) has an unlimited quantifier, and is followed by
448        something that cannot possibly match the quantified thing, the quantifier
449        is automatically "possessified".
450    
451    24. A recursive reference to a subpattern whose number was greater than 39
452        went wrong under certain circumstances in UTF-8 mode. This bug could also
453        have affected the operation of pcre_study().
454    
455    25. Realized that a little bit of performance could be had by replacing
456        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
457    
458    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
459    
460    27. Possessive quantifiers such as a++ were previously implemented by turning
461        them into atomic groups such as ($>a+). Now they have their own opcodes,
462        which improves performance. This includes the automatically created ones
463        from 23 above.
464    
465    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
466        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
467        the first matched character to be a colon. This applied both to named and
468        numbered groups.
469    
470    29. The ucpinternal.h header file was missing its idempotency #ifdef.
471    
472    30. I was sent a "project" file called libpcre.a.dev which I understand makes
473        building PCRE on Windows easier, so I have included it in the distribution.
474    
475    31. There is now a check in pcretest against a ridiculously large number being
476        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
477        loop, the loop is abandoned.
478    
479    32. Forward references to subpatterns in conditions such as (?(2)...) where
480        subpattern 2 is defined later cause pcre_compile() to search forwards in
481        the pattern for the relevant set of parentheses. This search went wrong
482        when there were unescaped parentheses in a character class, parentheses
483        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
484    
485    33. "Subroutine" calls and backreferences were previously restricted to
486        referencing subpatterns earlier in the regex. This restriction has now
487        been removed.
488    
489    34. Added a number of extra features that are going to be in Perl 5.10. On the
490        whole, these are just syntactic alternatives for features that PCRE had
491        previously implemented using the Python syntax or my own invention. The
492        other formats are all retained for compatibility.
493    
494        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
495            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
496            also .NET compatible.
497    
498        (b) A recursion or subroutine call to a named group can now be defined as
499            (?&name) as well as (?P>name).
500    
501        (c) A backreference to a named group can now be defined as \k<name> or
502            \k'name' as well as (?P=name). The new forms, as well as being in Perl
503            5.10, are also .NET compatible.
504    
505        (d) A conditional reference to a named group can now use the syntax
506            (?(<name>) or (?('name') as well as (?(name).
507    
508        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
509            groups (named and numbered) that are never evaluated inline, but can be
510            called as "subroutines" from elsewhere. In effect, the DEFINE condition
511            is always false. There may be only one alternative in such a group.
512    
513        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
514            as the simple (?(R). The condition is true only if the most recent
515            recursion is that of the given number or name. It does not search out
516            through the entire recursion stack.
517    
518        (g) The escape \gN or \g{N} has been added, where N is a positive or
519            negative number, specifying an absolute or relative reference.
520    
521    35. Tidied to get rid of some further signed/unsigned compiler warnings and
522        some "unreachable code" warnings.
523    
524    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
525        things, this adds five new scripts.
526    
527    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
528        There were also incompatibilities regarding the handling of \Q..\E inside
529        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
530        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
531    
532    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
533        matches an empty string, and forcibly breaks the loop. There were bugs in
534        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
535        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
536        separate and independent bugs (that affected different cases) have been
537        fixed.
538    
539    39. Refactored the code to abolish the use of different opcodes for small
540        capturing bracket numbers. This is a tidy that I avoided doing when I
541        removed the limit on the number of capturing brackets for 3.5 back in 2001.
542        The new approach is not only tidier, it makes it possible to reduce the
543        memory needed to fix the previous bug (38).
544    
545    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
546        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
547        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
548        mode.
549    
550    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
551        report.
552    
553    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
554        copy construction and assignment in the C++ wrapper.
555    
556    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
557        couple of bugs that could have given wrong results in the "--newline=crlf"
558        case.
559    
560    44. Added a number of casts and did some reorganization of signed/unsigned int
561        variables following suggestions from Dair Grant. Also renamed the variable
562        "this" as "item" because it is a C++ keyword.
563    
564    45. Arranged for dftables to add
565    
566          #include "pcre_internal.h"
567    
568        to pcre_chartables.c because without it, gcc 4.x may remove the array
569        definition from the final binary if PCRE is built into a static library and
570        dead code stripping is activated.
571    
572    46. For an unanchored pattern, if a match attempt fails at the start of a
573        newline sequence, and the newline setting is CRLF or ANY, and the next two
574        characters are CRLF, advance by two characters instead of one.
575    
576    
577    Version 6.7 04-Jul-06
578    ---------------------
579    
580     1. In order to handle tests when input lines are enormously long, pcretest has
581        been re-factored so that it automatically extends its buffers when
582        necessary. The code is crude, but this _is_ just a test program. The
583        default size has been increased from 32K to 50K.
584    
585     2. The code in pcre_study() was using the value of the re argument before
586        testing it for NULL. (Of course, in any sensible call of the function, it
587        won't be NULL.)
588    
589     3. The memmove() emulation function in pcre_internal.h, which is used on
590        systems that lack both memmove() and bcopy() - that is, hardly ever -
591        was missing a "static" storage class specifier.
592    
593     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
594        containing an extended class (one that cannot be represented by a bitmap
595        because it contains high-valued characters or Unicode property items, e.g.
596        [\pZ]). Almost always one would set UTF-8 mode when processing such a
597        pattern, but PCRE should not loop if you do not (it no longer does).
598        [Detail: two cases were found: (a) a repeated subpattern containing an
599        extended class; (b) a recursive reference to a subpattern that followed a
600        previous extended class. It wasn't skipping over the extended class
601        correctly when UTF-8 mode was not set.]
602    
603     5. A negated single-character class was not being recognized as fixed-length
604        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
605        compile error "lookbehind assertion is not fixed length".
606    
607     6. The RunPerlTest auxiliary script was showing an unexpected difference
608        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
609        write a Perl script that can interpret lines of an input file either as
610        byte characters or as UTF-8, which is what "perltest" was being required to
611        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
612        can't do is switch easily at run time between having the "use utf8;" pragma
613        or not. In the end, I fudged it by using the RunPerlTest script to insert
614        "use utf8;" explicitly for the UTF-8 tests.
615    
616     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
617        the end of the subject string, contrary to the documentation and to what
618        Perl does. This was true of both matching functions. Now it matches only at
619        the start of the subject and immediately after *internal* newlines.
620    
621     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
622        a pointer to an int instead of a pointer to an unsigned long int. This
623        caused problems on 64-bit systems.
624    
625     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
626        instance of the 'standard' template library not being so standard".
627    
628    10. There was no check on the number of named subpatterns nor the maximum
629        length of a subpattern name. The product of these values is used to compute
630        the size of the memory block for a compiled pattern. By supplying a very
631        long subpattern name and a large number of named subpatterns, the size
632        computation could be caused to overflow. This is now prevented by limiting
633        the length of names to 32 characters, and the number of named subpatterns
634        to 10,000.
635    
636    11. Subpatterns that are repeated with specific counts have to be replicated in
637        the compiled pattern. The size of memory for this was computed from the
638        length of the subpattern and the repeat count. The latter is limited to
639        65535, but there was no limit on the former, meaning that integer overflow
640        could in principle occur. The compiled length of a repeated subpattern is
641        now limited to 30,000 bytes in order to prevent this.
642    
643    12. Added the optional facility to have named substrings with the same name.
644    
645    13. Added the ability to use a named substring as a condition, using the
646        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
647        are numbers (not recommended). Forward references are permitted.
648    
649    14. Added forward references in named backreferences (if you see what I mean).
650    
651    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
652        pattern could run off the end of the subject. For example, the pattern
653        "(?s)(.{1,5})"8 did this with the subject "ab".
654    
655    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
656        PCRE_CASELESS was set when matching characters that were quantified with ?
657        or *.
658    
659    17. A character class other than a single negated character that had a minimum
660        but no maximum quantifier - for example [ab]{6,} - was not handled
661        correctly by pce_dfa_exec(). It would match only one character.
662    
663    18. A valid (though odd) pattern that looked like a POSIX character
664        class but used an invalid character after [ (for example [[,abc,]]) caused
665        pcre_compile() to give the error "Failed: internal error: code overflow" or
666        in some cases to crash with a glibc free() error. This could even happen if
667        the pattern terminated after [[ but there just happened to be a sequence of
668        letters, a binary zero, and a closing ] in the memory that followed.
669    
670    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
671        over the years. Originally (before any Unicode support), just the bottom 8
672        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
673        output from "man perlunicode" includes this:
674    
675          The regular expression compiler produces polymorphic opcodes.  That
676          is, the pattern adapts to the data and automatically switches to
677          the Unicode character scheme when presented with Unicode data--or
678          instead uses a traditional byte scheme when presented with byte
679          data.
680    
681        Sadly, a wide octal escape does not cause a switch, and in a string with
682        no other multibyte characters, these octal escapes are treated as before.
683        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
684        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
685        Unicode string.
686    
687        I have not perpetrated such confusion in PCRE. Up till now, it took just
688        the bottom 8 bits, as in old Perl. I have now made octal escapes with
689        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
690        translate to the appropriate multibyte character.
691    
692    29. Applied some refactoring to reduce the number of warnings from Microsoft
693        and Borland compilers. This has included removing the fudge introduced
694        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
695        a warning about an unused variable.
696    
697    21. PCRE has not included VT (character 0x0b) in the set of whitespace
698        characters since release 4.0, because Perl (from release 5.004) does not.
699        [Or at least, is documented not to: some releases seem to be in conflict
700        with the documentation.] However, when a pattern was studied with
701        pcre_study() and all its branches started with \s, PCRE still included VT
702        as a possible starting character. Of course, this did no harm; it just
703        caused an unnecessary match attempt.
704    
705    22. Removed a now-redundant internal flag bit that recorded the fact that case
706        dependency changed within the pattern. This was once needed for "required
707        byte" processing, but is no longer used. This recovers a now-scarce options
708        bit. Also moved the least significant internal flag bit to the most-
709        significant bit of the word, which was not previously used (hangover from
710        the days when it was an int rather than a uint) to free up another bit for
711        the future.
712    
713    23. Added support for CRLF line endings as well as CR and LF. As well as the
714        default being selectable at build time, it can now be changed at runtime
715        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
716        specify that it is scanning data with non-default line endings.
717    
718    24. Changed the definition of CXXLINK to make it agree with the definition of
719        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
720    
721    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
722        recursions. This makes a big different to stack usage for some patterns.
723    
724    26. If a subpattern containing a named recursion or subroutine reference such
725        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
726        the space required for the compiled pattern went wrong and gave too small a
727        value. Depending on the environment, this could lead to "Failed: internal
728        error: code overflow at offset 49" or "glibc detected double free or
729        corruption" errors.
730    
731    27. Applied patches from Google (a) to support the new newline modes and (b) to
732        advance over multibyte UTF-8 characters in GlobalReplace.
733    
734    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
735        difference for some implementation of PCRE in some Windows version.
736    
737    29. Added some extra testing facilities to pcretest:
738    
739        \q<number>   in a data line sets the "match limit" value
740        \Q<number>   in a data line sets the "match recursion limt" value
741        -S <number>  sets the stack size, where <number> is in megabytes
742    
743        The -S option isn't available for Windows.
744    
745    
746    Version 6.6 06-Feb-06
747    ---------------------
748    
749     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
750        in pcreposix.h. I have copied the definition from pcre.h.
751    
752     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
753        because pcre.h is no longer a built file.
754    
755     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
756        not normally included in the compiled code.
757    
758    
759  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
760  ---------------------  ---------------------
761    

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