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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.2 19-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        (g) (?| introduces a group in which the numbering of parentheses in each
45            alternative starts with the same number.
47        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
49     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
52     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
53        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
54        for detecting groups that can match an empty string.
56     9. A pattern with a very large number of alternatives (more than several
57        hundred) was running out of internal workspace during the pre-compile
58        phase, where pcre_compile() figures out how much memory will be needed. A
59        bit of new cunning has reduced the workspace needed for groups with
60        alternatives. The 1000-alternative test pattern now uses 12 bytes of
61        workspace instead of running out of the 4096 that are available.
63    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
65    11. Applied patch from Google to remove an optimization that didn't quite work.
66        The report of the bug said:
68          pcrecpp::RE("a*").FullMatch("aaa") matches, while
69          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
70          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
72    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
73        it matched the wrong number of bytes.
76    Version 7.1 24-Apr-07
77    ---------------------
79     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
80        that is more "standard", making use of automake and other Autotools. There
81        is some re-arrangement of the files and adjustment of comments consequent
82        on this.
84     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
85        for recursive directory scanning broke on some systems because the files
86        are not scanned in any specific order and on different systems the order
87        was different. A call to "sort" has been inserted into RunGrepTest for the
88        approprate test as a short-term fix. In the longer term there may be an
89        alternative.
91     3. I had an email from Eric Raymond about problems translating some of PCRE's
92        man pages to HTML (despite the fact that I distribute HTML pages, some
93        people do their own conversions for various reasons). The problems
94        concerned the use of low-level troff macros .br and .in. I have therefore
95        removed all such uses from the man pages (some were redundant, some could
96        be replaced by .nf/.fi pairs). The 132html script that I use to generate
97        HTML has been updated to handle .nf/.fi and to complain if it encounters
98        .br or .in.
100     4. Updated comments in configure.ac that get placed in config.h.in and also
101        arranged for config.h to be included in the distribution, with the name
102        config.h.generic, for the benefit of those who have to compile without
103        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
105     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
106        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
107        makevp.bat for the current PCRE, using the additional files
108        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
110     6. A Windows user reported a minor discrepancy with test 2, which turned out
111        to be caused by a trailing space on an input line that had got lost in his
112        copy. The trailing space was an accident, so I've just removed it.
114     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
115        that is needed.
117     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
118        as "const" (a) because they are and (b) because it helps the PHP
119        maintainers who have recently made a script to detect big data structures
120        in the php code that should be moved to the .rodata section. I remembered
121        to update Builducptable as well, so it won't revert if ucptable.h is ever
122        re-created.
124     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
125        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
126        order to be able to cut out the UTF-8 tables in the latter when UTF-8
127        support is not required. This saves 1.5-2K of code, which is important in
128        some applications.
130        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
131        so as not to refer to the tables, even though these functions will never be
132        called when UTF-8 support is disabled. Otherwise there are problems with a
133        shared library.
135    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
137        (a) It was defining its arguments as char * instead of void *.
139        (b) It was assuming that all moves were upwards in memory; this was true
140            a long time ago when I wrote it, but is no longer the case.
142        The emulated memove() is provided for those environments that have neither
143        memmove() nor bcopy(). I didn't think anyone used it these days, but that
144        is clearly not the case, as these two bugs were recently reported.
146    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
147        and Detrail to create the HTML documentation, the .txt form of the man
148        pages, and it removes trailing spaces from listed files. It also creates
149        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
150        case, it wraps all the #defines with #ifndefs. This script should be run
151        before "make dist".
153    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
154        with Unicode property support.
156        (a) For a maximizing quantifier, if the two different cases of the
157            character were of different lengths in their UTF-8 codings (there are
158            some cases like this - I found 11), and the matching function had to
159            back up over a mixture of the two cases, it incorrectly assumed they
160            were both the same length.
162        (b) When PCRE was configured to use the heap rather than the stack for
163            recursion during matching, it was not correctly preserving the data for
164            the other case of a UTF-8 character when checking ahead for a match
165            while processing a minimizing repeat. If the check also involved
166            matching a wide character, but failed, corruption could cause an
167            erroneous result when trying to check for a repeat of the original
168            character.
170    13. Some tidying changes to the testing mechanism:
172        (a) The RunTest script now detects the internal link size and whether there
173            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
174            values substituted by "configure". (The RunGrepTest script already did
175            this for UTF-8.) The configure.ac script no longer substitutes the
176            relevant variables.
178        (b) The debugging options /B and /D in pcretest show the compiled bytecode
179            with length and offset values. This means that the output is different
180            for different internal link sizes. Test 2 is skipped for link sizes
181            other than 2 because of this, bypassing the problem. Unfortunately,
182            there was also a test in test 3 (the locale tests) that used /B and
183            failed for link sizes other than 2. Rather than cut the whole test out,
184            I have added a new /Z option to pcretest that replaces the length and
185            offset values with spaces. This is now used to make test 3 independent
186            of link size. (Test 2 will be tidied up later.)
188    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
189        segmentation fault instead of returning the appropriate error message.
191    15. In multiline mode when the newline sequence was set to "any", the pattern
192        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
193        This doesn't seem right; it now treats the CRLF combination as the line
194        ending, and so does not match in that case. It's only a pattern such as ^$
195        that would hit this one: something like ^ABC$ would have failed after \r
196        and then tried again after \r\n.
198    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
199        in an attempt to make files that differ only in their line terminators
200        compare equal. This works on Linux.
202    17. Under certain error circumstances pcregrep might try to free random memory
203        as it exited. This is now fixed, thanks to valgrind.
205    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
206        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
207        was because its rules for how to advance for /g after matching an empty
208        string at the end of a line did not allow for this case. They now check for
209        it specially.
211    20. pcretest is supposed to handle patterns and data of any length, by
212        extending its buffers when necessary. It was getting this wrong when the
213        buffer for a data line had to be extended.
215    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
216        CRLF as a newline sequence.
218    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
219        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
220        I have nevertheless tidied it up.
222    23. Added some casts to kill warnings from HP-UX ia64 compiler.
224    24. Added a man page for pcre-config.
227    Version 7.0 19-Dec-06
228    ---------------------
230     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
231        moving to gcc 4.1.1.
233     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
234        sys/time.h, which is documented as needed for this function. It doesn't
235        seem to matter on Linux, but it showed up on some releases of OS X.
237     3. It seems that there are systems where bytes whose values are greater than
238        127 match isprint() in the "C" locale. The "C" locale should be the
239        default when a C program starts up. In most systems, only ASCII printing
240        characters match isprint(). This difference caused the output from pcretest
241        to vary, making some of the tests fail. I have changed pcretest so that:
243        (a) When it is outputting text in the compiled version of a pattern, bytes
244            other than 32-126 are always shown as hex escapes.
246        (b) When it is outputting text that is a matched part of a subject string,
247            it does the same, unless a different locale has been set for the match
248            (using the /L modifier). In this case, it uses isprint() to decide.
250     4. Fixed a major bug that caused incorrect computation of the amount of memory
251        required for a compiled pattern when options that changed within the
252        pattern affected the logic of the preliminary scan that determines the
253        length. The relevant options are -x, and -i in UTF-8 mode. The result was
254        that the computed length was too small. The symptoms of this bug were
255        either the PCRE error "internal error: code overflow" from pcre_compile(),
256        or a glibc crash with a message such as "pcretest: free(): invalid next
257        size (fast)". Examples of patterns that provoked this bug (shown in
258        pcretest format) are:
260          /(?-x: )/x
261          /(?x)(?-x: \s*#\s*)/
262          /((?i)[\x{c0}])/8
263          /(?i:[\x{c0}])/8
265        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
266        is now done differently.
268     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
269        wrapper classes; (b) implement a new function in the C++ scanner that is
270        more efficient than the old way of doing things because it avoids levels of
271        recursion in the regex matching; (c) add a paragraph to the documentation
272        for the FullMatch() function.
274     6. The escape sequence \n was being treated as whatever was defined as
275        "newline". Not only was this contrary to the documentation, which states
276        that \n is character 10 (hex 0A), but it also went horribly wrong when
277        "newline" was defined as CRLF. This has been fixed.
279     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
280        was being set to -1 for the "end of line" case (supposedly a value that no
281        character can have). Though this value is never used (the check for end of
282        line is "zero bytes in current character"), it caused compiler complaints.
283        I've changed it to 0xffffffff.
285     8. In pcre_version.c, the version string was being built by a sequence of
286        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
287        string (as it is for production releases) called a macro with an empty
288        argument. The C standard says the result of this is undefined. The gcc
289        compiler treats it as an empty string (which was what was wanted) but it is
290        reported that Visual C gives an error. The source has been hacked around to
291        avoid this problem.
293     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
294        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
295        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
296        of them did).
298    10. Originally, pcretest opened its input and output without "b"; then I was
299        told that "b" was needed in some environments, so it was added for release
300        5.0 to both the input and output. (It makes no difference on Unix-like
301        systems.) Later I was told that it is wrong for the input on Windows. I've
302        now abstracted the modes into two macros, to make it easier to fiddle with
303        them, and removed "b" from the input mode under Windows.
305    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
307    12. Added -help and --help to pcretest as an official way of being reminded
308        of the options.
310    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
311        and pcrecpp.cc because they annoy compilers at high warning levels.
313    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
315    15. Fixed an occurrence of == in configure.ac that should have been = (shell
316        scripts are not C programs :-) and which was not noticed because it works
317        on Linux.
319    16. pcretest is supposed to handle any length of pattern and data line (as one
320        line or as a continued sequence of lines) by extending its input buffer if
321        necessary. This feature was broken for very long pattern lines, leading to
322        a string of junk being passed to pcre_compile() if the pattern was longer
323        than about 50K.
325    17. I have done a major re-factoring of the way pcre_compile() computes the
326        amount of memory needed for a compiled pattern. Previously, there was code
327        that made a preliminary scan of the pattern in order to do this. That was
328        OK when PCRE was new, but as the facilities have expanded, it has become
329        harder and harder to keep it in step with the real compile phase, and there
330        have been a number of bugs (see for example, 4 above). I have now found a
331        cunning way of running the real compile function in a "fake" mode that
332        enables it to compute how much memory it would need, while actually only
333        ever using a few hundred bytes of working memory and without too many
334        tests of the mode. This should make future maintenance and development
335        easier. A side effect of this work is that the limit of 200 on the nesting
336        depth of parentheses has been removed (though this was never a serious
337        limitation, I suspect). However, there is a downside: pcre_compile() now
338        runs more slowly than before (30% or more, depending on the pattern). I
339        hope this isn't a big issue. There is no effect on runtime performance.
341    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
342        newline (only possible for the last line of a file) and it was a
343        pattern that set a locale (followed by /Lsomething), pcretest crashed.
345    19. Added additional timing features to pcretest. (1) The -tm option now times
346        matching only, not compiling. (2) Both -t and -tm can be followed, as a
347        separate command line item, by a number that specifies the number of
348        repeats to use when timing. The default is 50000; this gives better
349        precision, but takes uncomfortably long for very large patterns.
351    20. Extended pcre_study() to be more clever in cases where a branch of a
352        subpattern has no definite first character. For example, (a*|b*)[cd] would
353        previously give no result from pcre_study(). Now it recognizes that the
354        first character must be a, b, c, or d.
356    21. There was an incorrect error "recursive call could loop indefinitely" if
357        a subpattern (or the entire pattern) that was being tested for matching an
358        empty string contained only one non-empty item after a nested subpattern.
359        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
360        incorrectly, because the \d was being skipped in the check.
362    22. The pcretest program now has a new pattern option /B and a command line
363        option -b, which is equivalent to adding /B to every pattern. This causes
364        it to show the compiled bytecode, without the additional information that
365        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
366        is the same as /B/I).
368    23. A new optimization is now able automatically to treat some sequences such
369        as a*b as a*+b. More specifically, if something simple (such as a character
370        or a simple class like \d) has an unlimited quantifier, and is followed by
371        something that cannot possibly match the quantified thing, the quantifier
372        is automatically "possessified".
374    24. A recursive reference to a subpattern whose number was greater than 39
375        went wrong under certain circumstances in UTF-8 mode. This bug could also
376        have affected the operation of pcre_study().
378    25. Realized that a little bit of performance could be had by replacing
379        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
381    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
383    27. Possessive quantifiers such as a++ were previously implemented by turning
384        them into atomic groups such as ($>a+). Now they have their own opcodes,
385        which improves performance. This includes the automatically created ones
386        from 23 above.
388    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
389        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
390        the first matched character to be a colon. This applied both to named and
391        numbered groups.
393    29. The ucpinternal.h header file was missing its idempotency #ifdef.
395    30. I was sent a "project" file called libpcre.a.dev which I understand makes
396        building PCRE on Windows easier, so I have included it in the distribution.
398    31. There is now a check in pcretest against a ridiculously large number being
399        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
400        loop, the loop is abandoned.
402    32. Forward references to subpatterns in conditions such as (?(2)...) where
403        subpattern 2 is defined later cause pcre_compile() to search forwards in
404        the pattern for the relevant set of parentheses. This search went wrong
405        when there were unescaped parentheses in a character class, parentheses
406        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
408    33. "Subroutine" calls and backreferences were previously restricted to
409        referencing subpatterns earlier in the regex. This restriction has now
410        been removed.
412    34. Added a number of extra features that are going to be in Perl 5.10. On the
413        whole, these are just syntactic alternatives for features that PCRE had
414        previously implemented using the Python syntax or my own invention. The
415        other formats are all retained for compatibility.
417        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
418            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
419            also .NET compatible.
421        (b) A recursion or subroutine call to a named group can now be defined as
422            (?&name) as well as (?P>name).
424        (c) A backreference to a named group can now be defined as \k<name> or
425            \k'name' as well as (?P=name). The new forms, as well as being in Perl
426            5.10, are also .NET compatible.
428        (d) A conditional reference to a named group can now use the syntax
429            (?(<name>) or (?('name') as well as (?(name).
431        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
432            groups (named and numbered) that are never evaluated inline, but can be
433            called as "subroutines" from elsewhere. In effect, the DEFINE condition
434            is always false. There may be only one alternative in such a group.
436        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
437            as the simple (?(R). The condition is true only if the most recent
438            recursion is that of the given number or name. It does not search out
439            through the entire recursion stack.
441        (g) The escape \gN or \g{N} has been added, where N is a positive or
442            negative number, specifying an absolute or relative reference.
444    35. Tidied to get rid of some further signed/unsigned compiler warnings and
445        some "unreachable code" warnings.
447    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
448        things, this adds five new scripts.
450    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
451        There were also incompatibilities regarding the handling of \Q..\E inside
452        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
453        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
455    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
456        matches an empty string, and forcibly breaks the loop. There were bugs in
457        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
458        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
459        separate and independent bugs (that affected different cases) have been
460        fixed.
462    39. Refactored the code to abolish the use of different opcodes for small
463        capturing bracket numbers. This is a tidy that I avoided doing when I
464        removed the limit on the number of capturing brackets for 3.5 back in 2001.
465        The new approach is not only tidier, it makes it possible to reduce the
466        memory needed to fix the previous bug (38).
468    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
469        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
470        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
471        mode.
473    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
474        report.
476    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
477        copy construction and assignment in the C++ wrapper.
479    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
480        couple of bugs that could have given wrong results in the "--newline=crlf"
481        case.
483    44. Added a number of casts and did some reorganization of signed/unsigned int
484        variables following suggestions from Dair Grant. Also renamed the variable
485        "this" as "item" because it is a C++ keyword.
487    45. Arranged for dftables to add
489          #include "pcre_internal.h"
491        to pcre_chartables.c because without it, gcc 4.x may remove the array
492        definition from the final binary if PCRE is built into a static library and
493        dead code stripping is activated.
495    46. For an unanchored pattern, if a match attempt fails at the start of a
496        newline sequence, and the newline setting is CRLF or ANY, and the next two
497        characters are CRLF, advance by two characters instead of one.
500    Version 6.7 04-Jul-06
501    ---------------------
503     1. In order to handle tests when input lines are enormously long, pcretest has
504        been re-factored so that it automatically extends its buffers when
505        necessary. The code is crude, but this _is_ just a test program. The
506        default size has been increased from 32K to 50K.
508     2. The code in pcre_study() was using the value of the re argument before
509        testing it for NULL. (Of course, in any sensible call of the function, it
510        won't be NULL.)
512     3. The memmove() emulation function in pcre_internal.h, which is used on
513        systems that lack both memmove() and bcopy() - that is, hardly ever -
514        was missing a "static" storage class specifier.
516     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
517        containing an extended class (one that cannot be represented by a bitmap
518        because it contains high-valued characters or Unicode property items, e.g.
519        [\pZ]). Almost always one would set UTF-8 mode when processing such a
520        pattern, but PCRE should not loop if you do not (it no longer does).
521        [Detail: two cases were found: (a) a repeated subpattern containing an
522        extended class; (b) a recursive reference to a subpattern that followed a
523        previous extended class. It wasn't skipping over the extended class
524        correctly when UTF-8 mode was not set.]
526     5. A negated single-character class was not being recognized as fixed-length
527        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
528        compile error "lookbehind assertion is not fixed length".
530     6. The RunPerlTest auxiliary script was showing an unexpected difference
531        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
532        write a Perl script that can interpret lines of an input file either as
533        byte characters or as UTF-8, which is what "perltest" was being required to
534        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
535        can't do is switch easily at run time between having the "use utf8;" pragma
536        or not. In the end, I fudged it by using the RunPerlTest script to insert
537        "use utf8;" explicitly for the UTF-8 tests.
539     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
540        the end of the subject string, contrary to the documentation and to what
541        Perl does. This was true of both matching functions. Now it matches only at
542        the start of the subject and immediately after *internal* newlines.
544     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
545        a pointer to an int instead of a pointer to an unsigned long int. This
546        caused problems on 64-bit systems.
548     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
549        instance of the 'standard' template library not being so standard".
551    10. There was no check on the number of named subpatterns nor the maximum
552        length of a subpattern name. The product of these values is used to compute
553        the size of the memory block for a compiled pattern. By supplying a very
554        long subpattern name and a large number of named subpatterns, the size
555        computation could be caused to overflow. This is now prevented by limiting
556        the length of names to 32 characters, and the number of named subpatterns
557        to 10,000.
559    11. Subpatterns that are repeated with specific counts have to be replicated in
560        the compiled pattern. The size of memory for this was computed from the
561        length of the subpattern and the repeat count. The latter is limited to
562        65535, but there was no limit on the former, meaning that integer overflow
563        could in principle occur. The compiled length of a repeated subpattern is
564        now limited to 30,000 bytes in order to prevent this.
566    12. Added the optional facility to have named substrings with the same name.
568    13. Added the ability to use a named substring as a condition, using the
569        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
570        are numbers (not recommended). Forward references are permitted.
572    14. Added forward references in named backreferences (if you see what I mean).
574    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
575        pattern could run off the end of the subject. For example, the pattern
576        "(?s)(.{1,5})"8 did this with the subject "ab".
578    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
579        PCRE_CASELESS was set when matching characters that were quantified with ?
580        or *.
582    17. A character class other than a single negated character that had a minimum
583        but no maximum quantifier - for example [ab]{6,} - was not handled
584        correctly by pce_dfa_exec(). It would match only one character.
586    18. A valid (though odd) pattern that looked like a POSIX character
587        class but used an invalid character after [ (for example [[,abc,]]) caused
588        pcre_compile() to give the error "Failed: internal error: code overflow" or
589        in some cases to crash with a glibc free() error. This could even happen if
590        the pattern terminated after [[ but there just happened to be a sequence of
591        letters, a binary zero, and a closing ] in the memory that followed.
593    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
594        over the years. Originally (before any Unicode support), just the bottom 8
595        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
596        output from "man perlunicode" includes this:
598          The regular expression compiler produces polymorphic opcodes.  That
599          is, the pattern adapts to the data and automatically switches to
600          the Unicode character scheme when presented with Unicode data--or
601          instead uses a traditional byte scheme when presented with byte
602          data.
604        Sadly, a wide octal escape does not cause a switch, and in a string with
605        no other multibyte characters, these octal escapes are treated as before.
606        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
607        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
608        Unicode string.
610        I have not perpetrated such confusion in PCRE. Up till now, it took just
611        the bottom 8 bits, as in old Perl. I have now made octal escapes with
612        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
613        translate to the appropriate multibyte character.
615    29. Applied some refactoring to reduce the number of warnings from Microsoft
616        and Borland compilers. This has included removing the fudge introduced
617        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
618        a warning about an unused variable.
620    21. PCRE has not included VT (character 0x0b) in the set of whitespace
621        characters since release 4.0, because Perl (from release 5.004) does not.
622        [Or at least, is documented not to: some releases seem to be in conflict
623        with the documentation.] However, when a pattern was studied with
624        pcre_study() and all its branches started with \s, PCRE still included VT
625        as a possible starting character. Of course, this did no harm; it just
626        caused an unnecessary match attempt.
628    22. Removed a now-redundant internal flag bit that recorded the fact that case
629        dependency changed within the pattern. This was once needed for "required
630        byte" processing, but is no longer used. This recovers a now-scarce options
631        bit. Also moved the least significant internal flag bit to the most-
632        significant bit of the word, which was not previously used (hangover from
633        the days when it was an int rather than a uint) to free up another bit for
634        the future.
636    23. Added support for CRLF line endings as well as CR and LF. As well as the
637        default being selectable at build time, it can now be changed at runtime
638        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
639        specify that it is scanning data with non-default line endings.
641    24. Changed the definition of CXXLINK to make it agree with the definition of
642        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
644    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
645        recursions. This makes a big different to stack usage for some patterns.
647    26. If a subpattern containing a named recursion or subroutine reference such
648        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
649        the space required for the compiled pattern went wrong and gave too small a
650        value. Depending on the environment, this could lead to "Failed: internal
651        error: code overflow at offset 49" or "glibc detected double free or
652        corruption" errors.
654    27. Applied patches from Google (a) to support the new newline modes and (b) to
655        advance over multibyte UTF-8 characters in GlobalReplace.
657    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
658        difference for some implementation of PCRE in some Windows version.
660    29. Added some extra testing facilities to pcretest:
662        \q<number>   in a data line sets the "match limit" value
663        \Q<number>   in a data line sets the "match recursion limt" value
664        -S <number>  sets the stack size, where <number> is in megabytes
666        The -S option isn't available for Windows.
669    Version 6.6 06-Feb-06
670    ---------------------
672     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
673        in pcreposix.h. I have copied the definition from pcre.h.
675     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
676        because pcre.h is no longer a built file.
678     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
679        not normally included in the compiled code.
682    Version 6.5 01-Feb-06
683    ---------------------
685     1. When using the partial match feature with pcre_dfa_exec(), it was not
686        anchoring the second and subsequent partial matches at the new starting
687        point. This could lead to incorrect results. For example, with the pattern
688        /1234/, partially matching against "123" and then "a4" gave a match.
690     2. Changes to pcregrep:
692        (a) All non-match returns from pcre_exec() were being treated as failures
693            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
694            error message is output. Some extra information is given for the
695            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
696            probably the only errors that are likely to be caused by users (by
697            specifying a regex that has nested indefinite repeats, for instance).
698            If there are more than 20 of these errors, pcregrep is abandoned.
700        (b) A binary zero was treated as data while matching, but terminated the
701            output line if it was written out. This has been fixed: binary zeroes
702            are now no different to any other data bytes.
704        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
705            used to set a locale for matching. The --locale=xxxx long option has
706            been added (no short equivalent) to specify a locale explicitly on the
707            pcregrep command, overriding the environment variables.
709        (d) When -B was used with -n, some line numbers in the output were one less
710            than they should have been.
712        (e) Added the -o (--only-matching) option.
714        (f) If -A or -C was used with -c (count only), some lines of context were
715            accidentally printed for the final match.
717        (g) Added the -H (--with-filename) option.
719        (h) The combination of options -rh failed to suppress file names for files
720            that were found from directory arguments.
722        (i) Added the -D (--devices) and -d (--directories) options.
724        (j) Added the -F (--fixed-strings) option.
726        (k) Allow "-" to be used as a file name for -f as well as for a data file.
728        (l) Added the --colo(u)r option.
730        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
731            is not present by default.
733     3. A nasty bug was discovered in the handling of recursive patterns, that is,
734        items such as (?R) or (?1), when the recursion could match a number of
735        alternatives. If it matched one of the alternatives, but subsequently,
736        outside the recursion, there was a failure, the code tried to back up into
737        the recursion. However, because of the way PCRE is implemented, this is not
738        possible, and the result was an incorrect result from the match.
740        In order to prevent this happening, the specification of recursion has
741        been changed so that all such subpatterns are automatically treated as
742        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
744     4. I had overlooked the fact that, in some locales, there are characters for
745        which isalpha() is true but neither isupper() nor islower() are true. In
746        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
747        and ordfeminine) are like this. This affected the treatment of \w and \W
748        when they appeared in character classes, but not when they appeared outside
749        a character class. The bit map for "word" characters is now created
750        separately from the results of isalnum() instead of just taking it from the
751        upper, lower, and digit maps. (Plus the underscore character, of course.)
753     5. The above bug also affected the handling of POSIX character classes such as
754        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
755        permanent tables. Instead, the bit maps for such a class were previously
756        created as the appropriate unions of the upper, lower, and digit bitmaps.
757        Now they are created by subtraction from the [[:word:]] class, which has
758        its own bitmap.
760     6. The [[:blank:]] character class matches horizontal, but not vertical space.
761        It is created by subtracting the vertical space characters (\x09, \x0a,
762        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
763        subtraction was done in the overall bitmap for a character class, meaning
764        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
765        be recognized. This bug has been fixed.
767     7. Patches from the folks at Google:
769          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
770          real life, but is still worth protecting against".
772          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
773          regular expressions".
775          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
776          have it.
778          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
779          "configure" and the latter not, in order to fix a problem somebody had
780          with compiling the Arg class on HP-UX.
782          (e) Improve the error-handling of the C++ wrapper a little bit.
784          (f) New tests for checking recursion limiting.
786     8. The pcre_memmove() function, which is used only if the environment does not
787        have a standard memmove() function (and is therefore rarely compiled),
788        contained two bugs: (a) use of int instead of size_t, and (b) it was not
789        returning a result (though PCRE never actually uses the result).
791     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
792        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
793        returned instead of calling malloc() with an overflowing number that would
794        most likely cause subsequent chaos.
796    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
798    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
799        with this option is matched, the nmatch and pmatch options of regexec() are
800        ignored.
802    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
803        provided in case anyone wants to the the POSIX interface with UTF-8
804        strings.
806    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
807        C++ linking (needed for some HP-UX environments).
809    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
810        (unused parameter) and in the pcre_printint() function (omitted "default"
811        switch label when the default is to do nothing).
813    15. Added some code to make it possible, when PCRE is compiled as a C++
814        library, to replace subject pointers for pcre_exec() with a smart pointer
815        class, thus making it possible to process discontinuous strings.
817    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
818        much the same function. They were added by different people who were trying
819        to make PCRE easy to compile on non-Unix systems. It has been suggested
820        that PCRE_EXPORT be abolished now that there is more automatic apparatus
821        for compiling on Windows systems. I have therefore replaced it with
822        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
823        defaults to "extern" for C or "extern C" for C++, which works fine on
824        Unix-like systems. It is now possible to override the value of PCRE_DATA_
825        SCOPE with something explicit in config.h. In addition:
827        (a) pcreposix.h still had just "extern" instead of either of these macros;
828            I have replaced it with PCRE_DATA_SCOPE.
830        (b) Functions such as _pcre_xclass(), which are internal to the library,
831            but external in the C sense, all had PCRE_EXPORT in their definitions.
832            This is apparently wrong for the Windows case, so I have removed it.
833            (It makes no difference on Unix-like systems.)
835    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
836        of recursive calls to match(). This is different to MATCH_LIMIT because
837        that limits the total number of calls to match(), not all of which increase
838        the depth of recursion. Limiting the recursion depth limits the amount of
839        stack (or heap if NO_RECURSE is set) that is used. The default can be set
840        when PCRE is compiled, and changed at run time. A patch from Google adds
841        this functionality to the C++ interface.
843    18. Changes to the handling of Unicode character properties:
845        (a) Updated the table to Unicode 4.1.0.
847        (b) Recognize characters that are not in the table as "Cn" (undefined).
849        (c) I revised the way the table is implemented to a much improved format
850            which includes recognition of ranges. It now supports the ranges that
851            are defined in UnicodeData.txt, and it also amalgamates other
852            characters into ranges. This has reduced the number of entries in the
853            table from around 16,000 to around 3,000, thus reducing its size
854            considerably. I realized I did not need to use a tree structure after
855            all - a binary chop search is just as efficient. Having reduced the
856            number of entries, I extended their size from 6 bytes to 8 bytes to
857            allow for more data.
859        (d) Added support for Unicode script names via properties such as \p{Han}.
861    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
862        matching that character.
864    20. When matching a repeated Unicode property with a minimum greater than zero,
865        (for example \pL{2,}), PCRE could look past the end of the subject if it
866        reached it while seeking the minimum number of characters. This could
867        happen only if some of the characters were more than one byte long, because
868        there is a check for at least the minimum number of bytes.
870    21. Refactored the implementation of \p and \P so as to be more general, to
871        allow for more different types of property in future. This has changed the
872        compiled form incompatibly. Anybody with saved compiled patterns that use
873        \p or \P will have to recompile them.
875    22. Added "Any" and "L&" to the supported property types.
877    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
878        but give a compile time error if the value is greater than 0xff.
880    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
881        accidentally not being installed or uninstalled.
883    25. The pcre.h file was built from pcre.h.in, but the only changes that were
884        made were to insert the current release number. This seemed silly, because
885        it made things harder for people building PCRE on systems that don't run
886        "configure". I have turned pcre.h into a distributed file, no longer built
887        by "configure", with the version identification directly included. There is
888        no longer a pcre.h.in file.
890        However, this change necessitated a change to the pcre-config script as
891        well. It is built from pcre-config.in, and one of the substitutions was the
892        release number. I have updated configure.ac so that ./configure now finds
893        the release number by grepping pcre.h.
895    26. Added the ability to run the tests under valgrind.
898    Version 6.4 05-Sep-05
899    ---------------------
901     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
902        "--" to be printed when multiple files were scanned, even when none of the
903        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
904        consider it to be a bug, and have restored the previous behaviour.
906     2. A couple of code tidies to get rid of compiler warnings.
908     3. The pcretest program used to cheat by referring to symbols in the library
909        whose names begin with _pcre_. These are internal symbols that are not
910        really supposed to be visible externally, and in some environments it is
911        possible to suppress them. The cheating is now confined to including
912        certain files from the library's source, which is a bit cleaner.
914     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
915        file's purpose clearer.
917     5. Reorganized pcre_ucp_findchar().
920  Version 6.3 15-Aug-05  Version 6.3 15-Aug-05
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