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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.2 05-June-07
5    ---------------------
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.
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.
13     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
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.
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.
25     6. Added more features from the forthcoming Perl 5.10:
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.
30        (b) (?+n) is also a relative subroutine call; it refers to the nth next
31            to be opened parentheses.
33        (c) Conditions that refer to capturing parentheses can be specified
34            relatively, for example, (?(-2)... or (?(+3)...
36        (d) \K resets the start of the current match so that everything before
37            is not part of it.
39        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
41        (f) \g{name} is another synonym - part of Perl 5.10's unification of
42            reference syntax.
44     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
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.
51     9. A pattern with a very large number of alternatives (more than several
52        hundred) was running out of internal workspace during the pre-compile
53        phase, where pcre_compile() figures out how much memory will be needed. A
54        bit of new cunning has reduced the workspace needed for groups with
55        alternatives. The 1000-alternative test pattern now uses 12 bytes of
56        workspace instead of running out of the 4096 that are available.
59    Version 7.1 24-Apr-07
60    ---------------------
62     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
63        that is more "standard", making use of automake and other Autotools. There
64        is some re-arrangement of the files and adjustment of comments consequent
65        on this.
67     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
68        for recursive directory scanning broke on some systems because the files
69        are not scanned in any specific order and on different systems the order
70        was different. A call to "sort" has been inserted into RunGrepTest for the
71        approprate test as a short-term fix. In the longer term there may be an
72        alternative.
74     3. I had an email from Eric Raymond about problems translating some of PCRE's
75        man pages to HTML (despite the fact that I distribute HTML pages, some
76        people do their own conversions for various reasons). The problems
77        concerned the use of low-level troff macros .br and .in. I have therefore
78        removed all such uses from the man pages (some were redundant, some could
79        be replaced by .nf/.fi pairs). The 132html script that I use to generate
80        HTML has been updated to handle .nf/.fi and to complain if it encounters
81        .br or .in.
83     4. Updated comments in configure.ac that get placed in config.h.in and also
84        arranged for config.h to be included in the distribution, with the name
85        config.h.generic, for the benefit of those who have to compile without
86        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
88     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
89        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
90        makevp.bat for the current PCRE, using the additional files
91        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
93     6. A Windows user reported a minor discrepancy with test 2, which turned out
94        to be caused by a trailing space on an input line that had got lost in his
95        copy. The trailing space was an accident, so I've just removed it.
97     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
98        that is needed.
100     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
101        as "const" (a) because they are and (b) because it helps the PHP
102        maintainers who have recently made a script to detect big data structures
103        in the php code that should be moved to the .rodata section. I remembered
104        to update Builducptable as well, so it won't revert if ucptable.h is ever
105        re-created.
107     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
108        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
109        order to be able to cut out the UTF-8 tables in the latter when UTF-8
110        support is not required. This saves 1.5-2K of code, which is important in
111        some applications.
113        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
114        so as not to refer to the tables, even though these functions will never be
115        called when UTF-8 support is disabled. Otherwise there are problems with a
116        shared library.
118    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
120        (a) It was defining its arguments as char * instead of void *.
122        (b) It was assuming that all moves were upwards in memory; this was true
123            a long time ago when I wrote it, but is no longer the case.
125        The emulated memove() is provided for those environments that have neither
126        memmove() nor bcopy(). I didn't think anyone used it these days, but that
127        is clearly not the case, as these two bugs were recently reported.
129    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
130        and Detrail to create the HTML documentation, the .txt form of the man
131        pages, and it removes trailing spaces from listed files. It also creates
132        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
133        case, it wraps all the #defines with #ifndefs. This script should be run
134        before "make dist".
136    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
137        with Unicode property support.
139        (a) For a maximizing quantifier, if the two different cases of the
140            character were of different lengths in their UTF-8 codings (there are
141            some cases like this - I found 11), and the matching function had to
142            back up over a mixture of the two cases, it incorrectly assumed they
143            were both the same length.
145        (b) When PCRE was configured to use the heap rather than the stack for
146            recursion during matching, it was not correctly preserving the data for
147            the other case of a UTF-8 character when checking ahead for a match
148            while processing a minimizing repeat. If the check also involved
149            matching a wide character, but failed, corruption could cause an
150            erroneous result when trying to check for a repeat of the original
151            character.
153    13. Some tidying changes to the testing mechanism:
155        (a) The RunTest script now detects the internal link size and whether there
156            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
157            values substituted by "configure". (The RunGrepTest script already did
158            this for UTF-8.) The configure.ac script no longer substitutes the
159            relevant variables.
161        (b) The debugging options /B and /D in pcretest show the compiled bytecode
162            with length and offset values. This means that the output is different
163            for different internal link sizes. Test 2 is skipped for link sizes
164            other than 2 because of this, bypassing the problem. Unfortunately,
165            there was also a test in test 3 (the locale tests) that used /B and
166            failed for link sizes other than 2. Rather than cut the whole test out,
167            I have added a new /Z option to pcretest that replaces the length and
168            offset values with spaces. This is now used to make test 3 independent
169            of link size. (Test 2 will be tidied up later.)
171    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
172        segmentation fault instead of returning the appropriate error message.
174    15. In multiline mode when the newline sequence was set to "any", the pattern
175        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
176        This doesn't seem right; it now treats the CRLF combination as the line
177        ending, and so does not match in that case. It's only a pattern such as ^$
178        that would hit this one: something like ^ABC$ would have failed after \r
179        and then tried again after \r\n.
181    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
182        in an attempt to make files that differ only in their line terminators
183        compare equal. This works on Linux.
185    17. Under certain error circumstances pcregrep might try to free random memory
186        as it exited. This is now fixed, thanks to valgrind.
188    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
189        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
190        was because its rules for how to advance for /g after matching an empty
191        string at the end of a line did not allow for this case. They now check for
192        it specially.
194    20. pcretest is supposed to handle patterns and data of any length, by
195        extending its buffers when necessary. It was getting this wrong when the
196        buffer for a data line had to be extended.
198    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
199        CRLF as a newline sequence.
201    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
202        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
203        I have nevertheless tidied it up.
205    23. Added some casts to kill warnings from HP-UX ia64 compiler.
207    24. Added a man page for pcre-config.
210    Version 7.0 19-Dec-06
211    ---------------------
213     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
214        moving to gcc 4.1.1.
216     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
217        sys/time.h, which is documented as needed for this function. It doesn't
218        seem to matter on Linux, but it showed up on some releases of OS X.
220     3. It seems that there are systems where bytes whose values are greater than
221        127 match isprint() in the "C" locale. The "C" locale should be the
222        default when a C program starts up. In most systems, only ASCII printing
223        characters match isprint(). This difference caused the output from pcretest
224        to vary, making some of the tests fail. I have changed pcretest so that:
226        (a) When it is outputting text in the compiled version of a pattern, bytes
227            other than 32-126 are always shown as hex escapes.
229        (b) When it is outputting text that is a matched part of a subject string,
230            it does the same, unless a different locale has been set for the match
231            (using the /L modifier). In this case, it uses isprint() to decide.
233     4. Fixed a major bug that caused incorrect computation of the amount of memory
234        required for a compiled pattern when options that changed within the
235        pattern affected the logic of the preliminary scan that determines the
236        length. The relevant options are -x, and -i in UTF-8 mode. The result was
237        that the computed length was too small. The symptoms of this bug were
238        either the PCRE error "internal error: code overflow" from pcre_compile(),
239        or a glibc crash with a message such as "pcretest: free(): invalid next
240        size (fast)". Examples of patterns that provoked this bug (shown in
241        pcretest format) are:
243          /(?-x: )/x
244          /(?x)(?-x: \s*#\s*)/
245          /((?i)[\x{c0}])/8
246          /(?i:[\x{c0}])/8
248        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
249        is now done differently.
251     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
252        wrapper classes; (b) implement a new function in the C++ scanner that is
253        more efficient than the old way of doing things because it avoids levels of
254        recursion in the regex matching; (c) add a paragraph to the documentation
255        for the FullMatch() function.
257     6. The escape sequence \n was being treated as whatever was defined as
258        "newline". Not only was this contrary to the documentation, which states
259        that \n is character 10 (hex 0A), but it also went horribly wrong when
260        "newline" was defined as CRLF. This has been fixed.
262     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
263        was being set to -1 for the "end of line" case (supposedly a value that no
264        character can have). Though this value is never used (the check for end of
265        line is "zero bytes in current character"), it caused compiler complaints.
266        I've changed it to 0xffffffff.
268     8. In pcre_version.c, the version string was being built by a sequence of
269        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
270        string (as it is for production releases) called a macro with an empty
271        argument. The C standard says the result of this is undefined. The gcc
272        compiler treats it as an empty string (which was what was wanted) but it is
273        reported that Visual C gives an error. The source has been hacked around to
274        avoid this problem.
276     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
277        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
278        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
279        of them did).
281    10. Originally, pcretest opened its input and output without "b"; then I was
282        told that "b" was needed in some environments, so it was added for release
283        5.0 to both the input and output. (It makes no difference on Unix-like
284        systems.) Later I was told that it is wrong for the input on Windows. I've
285        now abstracted the modes into two macros, to make it easier to fiddle with
286        them, and removed "b" from the input mode under Windows.
288    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
290    12. Added -help and --help to pcretest as an official way of being reminded
291        of the options.
293    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
294        and pcrecpp.cc because they annoy compilers at high warning levels.
296    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
298    15. Fixed an occurrence of == in configure.ac that should have been = (shell
299        scripts are not C programs :-) and which was not noticed because it works
300        on Linux.
302    16. pcretest is supposed to handle any length of pattern and data line (as one
303        line or as a continued sequence of lines) by extending its input buffer if
304        necessary. This feature was broken for very long pattern lines, leading to
305        a string of junk being passed to pcre_compile() if the pattern was longer
306        than about 50K.
308    17. I have done a major re-factoring of the way pcre_compile() computes the
309        amount of memory needed for a compiled pattern. Previously, there was code
310        that made a preliminary scan of the pattern in order to do this. That was
311        OK when PCRE was new, but as the facilities have expanded, it has become
312        harder and harder to keep it in step with the real compile phase, and there
313        have been a number of bugs (see for example, 4 above). I have now found a
314        cunning way of running the real compile function in a "fake" mode that
315        enables it to compute how much memory it would need, while actually only
316        ever using a few hundred bytes of working memory and without too many
317        tests of the mode. This should make future maintenance and development
318        easier. A side effect of this work is that the limit of 200 on the nesting
319        depth of parentheses has been removed (though this was never a serious
320        limitation, I suspect). However, there is a downside: pcre_compile() now
321        runs more slowly than before (30% or more, depending on the pattern). I
322        hope this isn't a big issue. There is no effect on runtime performance.
324    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
325        newline (only possible for the last line of a file) and it was a
326        pattern that set a locale (followed by /Lsomething), pcretest crashed.
328    19. Added additional timing features to pcretest. (1) The -tm option now times
329        matching only, not compiling. (2) Both -t and -tm can be followed, as a
330        separate command line item, by a number that specifies the number of
331        repeats to use when timing. The default is 50000; this gives better
332        precision, but takes uncomfortably long for very large patterns.
334    20. Extended pcre_study() to be more clever in cases where a branch of a
335        subpattern has no definite first character. For example, (a*|b*)[cd] would
336        previously give no result from pcre_study(). Now it recognizes that the
337        first character must be a, b, c, or d.
339    21. There was an incorrect error "recursive call could loop indefinitely" if
340        a subpattern (or the entire pattern) that was being tested for matching an
341        empty string contained only one non-empty item after a nested subpattern.
342        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
343        incorrectly, because the \d was being skipped in the check.
345    22. The pcretest program now has a new pattern option /B and a command line
346        option -b, which is equivalent to adding /B to every pattern. This causes
347        it to show the compiled bytecode, without the additional information that
348        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
349        is the same as /B/I).
351    23. A new optimization is now able automatically to treat some sequences such
352        as a*b as a*+b. More specifically, if something simple (such as a character
353        or a simple class like \d) has an unlimited quantifier, and is followed by
354        something that cannot possibly match the quantified thing, the quantifier
355        is automatically "possessified".
357    24. A recursive reference to a subpattern whose number was greater than 39
358        went wrong under certain circumstances in UTF-8 mode. This bug could also
359        have affected the operation of pcre_study().
361    25. Realized that a little bit of performance could be had by replacing
362        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
364    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
366    27. Possessive quantifiers such as a++ were previously implemented by turning
367        them into atomic groups such as ($>a+). Now they have their own opcodes,
368        which improves performance. This includes the automatically created ones
369        from 23 above.
371    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
372        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
373        the first matched character to be a colon. This applied both to named and
374        numbered groups.
376    29. The ucpinternal.h header file was missing its idempotency #ifdef.
378    30. I was sent a "project" file called libpcre.a.dev which I understand makes
379        building PCRE on Windows easier, so I have included it in the distribution.
381    31. There is now a check in pcretest against a ridiculously large number being
382        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
383        loop, the loop is abandoned.
385    32. Forward references to subpatterns in conditions such as (?(2)...) where
386        subpattern 2 is defined later cause pcre_compile() to search forwards in
387        the pattern for the relevant set of parentheses. This search went wrong
388        when there were unescaped parentheses in a character class, parentheses
389        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
391    33. "Subroutine" calls and backreferences were previously restricted to
392        referencing subpatterns earlier in the regex. This restriction has now
393        been removed.
395    34. Added a number of extra features that are going to be in Perl 5.10. On the
396        whole, these are just syntactic alternatives for features that PCRE had
397        previously implemented using the Python syntax or my own invention. The
398        other formats are all retained for compatibility.
400        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
401            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
402            also .NET compatible.
404        (b) A recursion or subroutine call to a named group can now be defined as
405            (?&name) as well as (?P>name).
407        (c) A backreference to a named group can now be defined as \k<name> or
408            \k'name' as well as (?P=name). The new forms, as well as being in Perl
409            5.10, are also .NET compatible.
411        (d) A conditional reference to a named group can now use the syntax
412            (?(<name>) or (?('name') as well as (?(name).
414        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
415            groups (named and numbered) that are never evaluated inline, but can be
416            called as "subroutines" from elsewhere. In effect, the DEFINE condition
417            is always false. There may be only one alternative in such a group.
419        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
420            as the simple (?(R). The condition is true only if the most recent
421            recursion is that of the given number or name. It does not search out
422            through the entire recursion stack.
424        (g) The escape \gN or \g{N} has been added, where N is a positive or
425            negative number, specifying an absolute or relative reference.
427    35. Tidied to get rid of some further signed/unsigned compiler warnings and
428        some "unreachable code" warnings.
430    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
431        things, this adds five new scripts.
433    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
434        There were also incompatibilities regarding the handling of \Q..\E inside
435        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
436        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
438    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
439        matches an empty string, and forcibly breaks the loop. There were bugs in
440        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
441        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
442        separate and independent bugs (that affected different cases) have been
443        fixed.
445    39. Refactored the code to abolish the use of different opcodes for small
446        capturing bracket numbers. This is a tidy that I avoided doing when I
447        removed the limit on the number of capturing brackets for 3.5 back in 2001.
448        The new approach is not only tidier, it makes it possible to reduce the
449        memory needed to fix the previous bug (38).
451    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
452        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
453        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
454        mode.
456    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
457        report.
459    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
460        copy construction and assignment in the C++ wrapper.
462    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
463        couple of bugs that could have given wrong results in the "--newline=crlf"
464        case.
466    44. Added a number of casts and did some reorganization of signed/unsigned int
467        variables following suggestions from Dair Grant. Also renamed the variable
468        "this" as "item" because it is a C++ keyword.
470    45. Arranged for dftables to add
472          #include "pcre_internal.h"
474        to pcre_chartables.c because without it, gcc 4.x may remove the array
475        definition from the final binary if PCRE is built into a static library and
476        dead code stripping is activated.
478    46. For an unanchored pattern, if a match attempt fails at the start of a
479        newline sequence, and the newline setting is CRLF or ANY, and the next two
480        characters are CRLF, advance by two characters instead of one.
483    Version 6.7 04-Jul-06
484    ---------------------
486     1. In order to handle tests when input lines are enormously long, pcretest has
487        been re-factored so that it automatically extends its buffers when
488        necessary. The code is crude, but this _is_ just a test program. The
489        default size has been increased from 32K to 50K.
491     2. The code in pcre_study() was using the value of the re argument before
492        testing it for NULL. (Of course, in any sensible call of the function, it
493        won't be NULL.)
495     3. The memmove() emulation function in pcre_internal.h, which is used on
496        systems that lack both memmove() and bcopy() - that is, hardly ever -
497        was missing a "static" storage class specifier.
499     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
500        containing an extended class (one that cannot be represented by a bitmap
501        because it contains high-valued characters or Unicode property items, e.g.
502        [\pZ]). Almost always one would set UTF-8 mode when processing such a
503        pattern, but PCRE should not loop if you do not (it no longer does).
504        [Detail: two cases were found: (a) a repeated subpattern containing an
505        extended class; (b) a recursive reference to a subpattern that followed a
506        previous extended class. It wasn't skipping over the extended class
507        correctly when UTF-8 mode was not set.]
509     5. A negated single-character class was not being recognized as fixed-length
510        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
511        compile error "lookbehind assertion is not fixed length".
513     6. The RunPerlTest auxiliary script was showing an unexpected difference
514        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
515        write a Perl script that can interpret lines of an input file either as
516        byte characters or as UTF-8, which is what "perltest" was being required to
517        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
518        can't do is switch easily at run time between having the "use utf8;" pragma
519        or not. In the end, I fudged it by using the RunPerlTest script to insert
520        "use utf8;" explicitly for the UTF-8 tests.
522     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
523        the end of the subject string, contrary to the documentation and to what
524        Perl does. This was true of both matching functions. Now it matches only at
525        the start of the subject and immediately after *internal* newlines.
527     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
528        a pointer to an int instead of a pointer to an unsigned long int. This
529        caused problems on 64-bit systems.
531     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
532        instance of the 'standard' template library not being so standard".
534    10. There was no check on the number of named subpatterns nor the maximum
535        length of a subpattern name. The product of these values is used to compute
536        the size of the memory block for a compiled pattern. By supplying a very
537        long subpattern name and a large number of named subpatterns, the size
538        computation could be caused to overflow. This is now prevented by limiting
539        the length of names to 32 characters, and the number of named subpatterns
540        to 10,000.
542    11. Subpatterns that are repeated with specific counts have to be replicated in
543        the compiled pattern. The size of memory for this was computed from the
544        length of the subpattern and the repeat count. The latter is limited to
545        65535, but there was no limit on the former, meaning that integer overflow
546        could in principle occur. The compiled length of a repeated subpattern is
547        now limited to 30,000 bytes in order to prevent this.
549    12. Added the optional facility to have named substrings with the same name.
551    13. Added the ability to use a named substring as a condition, using the
552        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
553        are numbers (not recommended). Forward references are permitted.
555    14. Added forward references in named backreferences (if you see what I mean).
557    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
558        pattern could run off the end of the subject. For example, the pattern
559        "(?s)(.{1,5})"8 did this with the subject "ab".
561    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
562        PCRE_CASELESS was set when matching characters that were quantified with ?
563        or *.
565    17. A character class other than a single negated character that had a minimum
566        but no maximum quantifier - for example [ab]{6,} - was not handled
567        correctly by pce_dfa_exec(). It would match only one character.
569    18. A valid (though odd) pattern that looked like a POSIX character
570        class but used an invalid character after [ (for example [[,abc,]]) caused
571        pcre_compile() to give the error "Failed: internal error: code overflow" or
572        in some cases to crash with a glibc free() error. This could even happen if
573        the pattern terminated after [[ but there just happened to be a sequence of
574        letters, a binary zero, and a closing ] in the memory that followed.
576    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
577        over the years. Originally (before any Unicode support), just the bottom 8
578        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
579        output from "man perlunicode" includes this:
581          The regular expression compiler produces polymorphic opcodes.  That
582          is, the pattern adapts to the data and automatically switches to
583          the Unicode character scheme when presented with Unicode data--or
584          instead uses a traditional byte scheme when presented with byte
585          data.
587        Sadly, a wide octal escape does not cause a switch, and in a string with
588        no other multibyte characters, these octal escapes are treated as before.
589        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
590        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
591        Unicode string.
593        I have not perpetrated such confusion in PCRE. Up till now, it took just
594        the bottom 8 bits, as in old Perl. I have now made octal escapes with
595        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
596        translate to the appropriate multibyte character.
598    29. Applied some refactoring to reduce the number of warnings from Microsoft
599        and Borland compilers. This has included removing the fudge introduced
600        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
601        a warning about an unused variable.
603    21. PCRE has not included VT (character 0x0b) in the set of whitespace
604        characters since release 4.0, because Perl (from release 5.004) does not.
605        [Or at least, is documented not to: some releases seem to be in conflict
606        with the documentation.] However, when a pattern was studied with
607        pcre_study() and all its branches started with \s, PCRE still included VT
608        as a possible starting character. Of course, this did no harm; it just
609        caused an unnecessary match attempt.
611    22. Removed a now-redundant internal flag bit that recorded the fact that case
612        dependency changed within the pattern. This was once needed for "required
613        byte" processing, but is no longer used. This recovers a now-scarce options
614        bit. Also moved the least significant internal flag bit to the most-
615        significant bit of the word, which was not previously used (hangover from
616        the days when it was an int rather than a uint) to free up another bit for
617        the future.
619    23. Added support for CRLF line endings as well as CR and LF. As well as the
620        default being selectable at build time, it can now be changed at runtime
621        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
622        specify that it is scanning data with non-default line endings.
624    24. Changed the definition of CXXLINK to make it agree with the definition of
625        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
627    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
628        recursions. This makes a big different to stack usage for some patterns.
630    26. If a subpattern containing a named recursion or subroutine reference such
631        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
632        the space required for the compiled pattern went wrong and gave too small a
633        value. Depending on the environment, this could lead to "Failed: internal
634        error: code overflow at offset 49" or "glibc detected double free or
635        corruption" errors.
637    27. Applied patches from Google (a) to support the new newline modes and (b) to
638        advance over multibyte UTF-8 characters in GlobalReplace.
640    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
641        difference for some implementation of PCRE in some Windows version.
643    29. Added some extra testing facilities to pcretest:
645        \q<number>   in a data line sets the "match limit" value
646        \Q<number>   in a data line sets the "match recursion limt" value
647        -S <number>  sets the stack size, where <number> is in megabytes
649        The -S option isn't available for Windows.
652    Version 6.6 06-Feb-06
653    ---------------------
655     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
656        in pcreposix.h. I have copied the definition from pcre.h.
658     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
659        because pcre.h is no longer a built file.
661     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
662        not normally included in the compiled code.
665    Version 6.5 01-Feb-06
666    ---------------------
668     1. When using the partial match feature with pcre_dfa_exec(), it was not
669        anchoring the second and subsequent partial matches at the new starting
670        point. This could lead to incorrect results. For example, with the pattern
671        /1234/, partially matching against "123" and then "a4" gave a match.
673     2. Changes to pcregrep:
675        (a) All non-match returns from pcre_exec() were being treated as failures
676            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
677            error message is output. Some extra information is given for the
678            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
679            probably the only errors that are likely to be caused by users (by
680            specifying a regex that has nested indefinite repeats, for instance).
681            If there are more than 20 of these errors, pcregrep is abandoned.
683        (b) A binary zero was treated as data while matching, but terminated the
684            output line if it was written out. This has been fixed: binary zeroes
685            are now no different to any other data bytes.
687        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
688            used to set a locale for matching. The --locale=xxxx long option has
689            been added (no short equivalent) to specify a locale explicitly on the
690            pcregrep command, overriding the environment variables.
692        (d) When -B was used with -n, some line numbers in the output were one less
693            than they should have been.
695        (e) Added the -o (--only-matching) option.
697        (f) If -A or -C was used with -c (count only), some lines of context were
698            accidentally printed for the final match.
700        (g) Added the -H (--with-filename) option.
702        (h) The combination of options -rh failed to suppress file names for files
703            that were found from directory arguments.
705        (i) Added the -D (--devices) and -d (--directories) options.
707        (j) Added the -F (--fixed-strings) option.
709        (k) Allow "-" to be used as a file name for -f as well as for a data file.
711        (l) Added the --colo(u)r option.
713        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
714            is not present by default.
716     3. A nasty bug was discovered in the handling of recursive patterns, that is,
717        items such as (?R) or (?1), when the recursion could match a number of
718        alternatives. If it matched one of the alternatives, but subsequently,
719        outside the recursion, there was a failure, the code tried to back up into
720        the recursion. However, because of the way PCRE is implemented, this is not
721        possible, and the result was an incorrect result from the match.
723        In order to prevent this happening, the specification of recursion has
724        been changed so that all such subpatterns are automatically treated as
725        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
727     4. I had overlooked the fact that, in some locales, there are characters for
728        which isalpha() is true but neither isupper() nor islower() are true. In
729        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
730        and ordfeminine) are like this. This affected the treatment of \w and \W
731        when they appeared in character classes, but not when they appeared outside
732        a character class. The bit map for "word" characters is now created
733        separately from the results of isalnum() instead of just taking it from the
734        upper, lower, and digit maps. (Plus the underscore character, of course.)
736     5. The above bug also affected the handling of POSIX character classes such as
737        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
738        permanent tables. Instead, the bit maps for such a class were previously
739        created as the appropriate unions of the upper, lower, and digit bitmaps.
740        Now they are created by subtraction from the [[:word:]] class, which has
741        its own bitmap.
743     6. The [[:blank:]] character class matches horizontal, but not vertical space.
744        It is created by subtracting the vertical space characters (\x09, \x0a,
745        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
746        subtraction was done in the overall bitmap for a character class, meaning
747        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
748        be recognized. This bug has been fixed.
750     7. Patches from the folks at Google:
752          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
753          real life, but is still worth protecting against".
755          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
756          regular expressions".
758          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
759          have it.
761          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
762          "configure" and the latter not, in order to fix a problem somebody had
763          with compiling the Arg class on HP-UX.
765          (e) Improve the error-handling of the C++ wrapper a little bit.
767          (f) New tests for checking recursion limiting.
769     8. The pcre_memmove() function, which is used only if the environment does not
770        have a standard memmove() function (and is therefore rarely compiled),
771        contained two bugs: (a) use of int instead of size_t, and (b) it was not
772        returning a result (though PCRE never actually uses the result).
774     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
775        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
776        returned instead of calling malloc() with an overflowing number that would
777        most likely cause subsequent chaos.
779    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
781    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
782        with this option is matched, the nmatch and pmatch options of regexec() are
783        ignored.
785    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
786        provided in case anyone wants to the the POSIX interface with UTF-8
787        strings.
789    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
790        C++ linking (needed for some HP-UX environments).
792    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
793        (unused parameter) and in the pcre_printint() function (omitted "default"
794        switch label when the default is to do nothing).
796    15. Added some code to make it possible, when PCRE is compiled as a C++
797        library, to replace subject pointers for pcre_exec() with a smart pointer
798        class, thus making it possible to process discontinuous strings.
800    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
801        much the same function. They were added by different people who were trying
802        to make PCRE easy to compile on non-Unix systems. It has been suggested
803        that PCRE_EXPORT be abolished now that there is more automatic apparatus
804        for compiling on Windows systems. I have therefore replaced it with
805        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
806        defaults to "extern" for C or "extern C" for C++, which works fine on
807        Unix-like systems. It is now possible to override the value of PCRE_DATA_
808        SCOPE with something explicit in config.h. In addition:
810        (a) pcreposix.h still had just "extern" instead of either of these macros;
811            I have replaced it with PCRE_DATA_SCOPE.
813        (b) Functions such as _pcre_xclass(), which are internal to the library,
814            but external in the C sense, all had PCRE_EXPORT in their definitions.
815            This is apparently wrong for the Windows case, so I have removed it.
816            (It makes no difference on Unix-like systems.)
818    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
819        of recursive calls to match(). This is different to MATCH_LIMIT because
820        that limits the total number of calls to match(), not all of which increase
821        the depth of recursion. Limiting the recursion depth limits the amount of
822        stack (or heap if NO_RECURSE is set) that is used. The default can be set
823        when PCRE is compiled, and changed at run time. A patch from Google adds
824        this functionality to the C++ interface.
826    18. Changes to the handling of Unicode character properties:
828        (a) Updated the table to Unicode 4.1.0.
830        (b) Recognize characters that are not in the table as "Cn" (undefined).
832        (c) I revised the way the table is implemented to a much improved format
833            which includes recognition of ranges. It now supports the ranges that
834            are defined in UnicodeData.txt, and it also amalgamates other
835            characters into ranges. This has reduced the number of entries in the
836            table from around 16,000 to around 3,000, thus reducing its size
837            considerably. I realized I did not need to use a tree structure after
838            all - a binary chop search is just as efficient. Having reduced the
839            number of entries, I extended their size from 6 bytes to 8 bytes to
840            allow for more data.
842        (d) Added support for Unicode script names via properties such as \p{Han}.
844    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
845        matching that character.
847    20. When matching a repeated Unicode property with a minimum greater than zero,
848        (for example \pL{2,}), PCRE could look past the end of the subject if it
849        reached it while seeking the minimum number of characters. This could
850        happen only if some of the characters were more than one byte long, because
851        there is a check for at least the minimum number of bytes.
853    21. Refactored the implementation of \p and \P so as to be more general, to
854        allow for more different types of property in future. This has changed the
855        compiled form incompatibly. Anybody with saved compiled patterns that use
856        \p or \P will have to recompile them.
858    22. Added "Any" and "L&" to the supported property types.
860    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
861        but give a compile time error if the value is greater than 0xff.
863    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
864        accidentally not being installed or uninstalled.
866    25. The pcre.h file was built from pcre.h.in, but the only changes that were
867        made were to insert the current release number. This seemed silly, because
868        it made things harder for people building PCRE on systems that don't run
869        "configure". I have turned pcre.h into a distributed file, no longer built
870        by "configure", with the version identification directly included. There is
871        no longer a pcre.h.in file.
873        However, this change necessitated a change to the pcre-config script as
874        well. It is built from pcre-config.in, and one of the substitutions was the
875        release number. I have updated configure.ac so that ./configure now finds
876        the release number by grepping pcre.h.
878    26. Added the ability to run the tests under valgrind.
881    Version 6.4 05-Sep-05
882    ---------------------
884     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
885        "--" to be printed when multiple files were scanned, even when none of the
886        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
887        consider it to be a bug, and have restored the previous behaviour.
889     2. A couple of code tidies to get rid of compiler warnings.
891     3. The pcretest program used to cheat by referring to symbols in the library
892        whose names begin with _pcre_. These are internal symbols that are not
893        really supposed to be visible externally, and in some environments it is
894        possible to suppress them. The cheating is now confined to including
895        certain files from the library's source, which is a bit cleaner.
897     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
898        file's purpose clearer.
900     5. Reorganized pcre_ucp_findchar().
903  Version 6.3 15-Aug-05  Version 6.3 15-Aug-05
904  ---------------------  ---------------------

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