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

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