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revision 83 by nigel, Sat Feb 24 21:41:06 2007 UTC revision 159 by ph10, Wed May 2 10:27:18 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.2 01-May-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.
16    Version 7.1 24-Apr-07
17    ---------------------
19     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
20        that is more "standard", making use of automake and other Autotools. There
21        is some re-arrangement of the files and adjustment of comments consequent
22        on this.
24     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
25        for recursive directory scanning broke on some systems because the files
26        are not scanned in any specific order and on different systems the order
27        was different. A call to "sort" has been inserted into RunGrepTest for the
28        approprate test as a short-term fix. In the longer term there may be an
29        alternative.
31     3. I had an email from Eric Raymond about problems translating some of PCRE's
32        man pages to HTML (despite the fact that I distribute HTML pages, some
33        people do their own conversions for various reasons). The problems
34        concerned the use of low-level troff macros .br and .in. I have therefore
35        removed all such uses from the man pages (some were redundant, some could
36        be replaced by .nf/.fi pairs). The 132html script that I use to generate
37        HTML has been updated to handle .nf/.fi and to complain if it encounters
38        .br or .in.
40     4. Updated comments in configure.ac that get placed in config.h.in and also
41        arranged for config.h to be included in the distribution, with the name
42        config.h.generic, for the benefit of those who have to compile without
43        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
45     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
46        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
47        makevp.bat for the current PCRE, using the additional files
48        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
50     6. A Windows user reported a minor discrepancy with test 2, which turned out
51        to be caused by a trailing space on an input line that had got lost in his
52        copy. The trailing space was an accident, so I've just removed it.
54     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
55        that is needed.
57     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
58        as "const" (a) because they are and (b) because it helps the PHP
59        maintainers who have recently made a script to detect big data structures
60        in the php code that should be moved to the .rodata section. I remembered
61        to update Builducptable as well, so it won't revert if ucptable.h is ever
62        re-created.
64     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
65        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
66        order to be able to cut out the UTF-8 tables in the latter when UTF-8
67        support is not required. This saves 1.5-2K of code, which is important in
68        some applications.
70        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
71        so as not to refer to the tables, even though these functions will never be
72        called when UTF-8 support is disabled. Otherwise there are problems with a
73        shared library.
75    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
77        (a) It was defining its arguments as char * instead of void *.
79        (b) It was assuming that all moves were upwards in memory; this was true
80            a long time ago when I wrote it, but is no longer the case.
82        The emulated memove() is provided for those environments that have neither
83        memmove() nor bcopy(). I didn't think anyone used it these days, but that
84        is clearly not the case, as these two bugs were recently reported.
86    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
87        and Detrail to create the HTML documentation, the .txt form of the man
88        pages, and it removes trailing spaces from listed files. It also creates
89        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
90        case, it wraps all the #defines with #ifndefs. This script should be run
91        before "make dist".
93    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
94        with Unicode property support.
96        (a) For a maximizing quantifier, if the two different cases of the
97            character were of different lengths in their UTF-8 codings (there are
98            some cases like this - I found 11), and the matching function had to
99            back up over a mixture of the two cases, it incorrectly assumed they
100            were both the same length.
102        (b) When PCRE was configured to use the heap rather than the stack for
103            recursion during matching, it was not correctly preserving the data for
104            the other case of a UTF-8 character when checking ahead for a match
105            while processing a minimizing repeat. If the check also involved
106            matching a wide character, but failed, corruption could cause an
107            erroneous result when trying to check for a repeat of the original
108            character.
110    13. Some tidying changes to the testing mechanism:
112        (a) The RunTest script now detects the internal link size and whether there
113            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
114            values substituted by "configure". (The RunGrepTest script already did
115            this for UTF-8.) The configure.ac script no longer substitutes the
116            relevant variables.
118        (b) The debugging options /B and /D in pcretest show the compiled bytecode
119            with length and offset values. This means that the output is different
120            for different internal link sizes. Test 2 is skipped for link sizes
121            other than 2 because of this, bypassing the problem. Unfortunately,
122            there was also a test in test 3 (the locale tests) that used /B and
123            failed for link sizes other than 2. Rather than cut the whole test out,
124            I have added a new /Z option to pcretest that replaces the length and
125            offset values with spaces. This is now used to make test 3 independent
126            of link size. (Test 2 will be tidied up later.)
128    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
129        segmentation fault instead of returning the appropriate error message.
131    15. In multiline mode when the newline sequence was set to "any", the pattern
132        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
133        This doesn't seem right; it now treats the CRLF combination as the line
134        ending, and so does not match in that case. It's only a pattern such as ^$
135        that would hit this one: something like ^ABC$ would have failed after \r
136        and then tried again after \r\n.
138    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
139        in an attempt to make files that differ only in their line terminators
140        compare equal. This works on Linux.
142    17. Under certain error circumstances pcregrep might try to free random memory
143        as it exited. This is now fixed, thanks to valgrind.
145    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
146        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
147        was because its rules for how to advance for /g after matching an empty
148        string at the end of a line did not allow for this case. They now check for
149        it specially.
151    20. pcretest is supposed to handle patterns and data of any length, by
152        extending its buffers when necessary. It was getting this wrong when the
153        buffer for a data line had to be extended.
155    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
156        CRLF as a newline sequence.
158    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
159        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
160        I have nevertheless tidied it up.
162    23. Added some casts to kill warnings from HP-UX ia64 compiler.
164    24. Added a man page for pcre-config.
167    Version 7.0 19-Dec-06
168    ---------------------
170     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
171        moving to gcc 4.1.1.
173     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
174        sys/time.h, which is documented as needed for this function. It doesn't
175        seem to matter on Linux, but it showed up on some releases of OS X.
177     3. It seems that there are systems where bytes whose values are greater than
178        127 match isprint() in the "C" locale. The "C" locale should be the
179        default when a C program starts up. In most systems, only ASCII printing
180        characters match isprint(). This difference caused the output from pcretest
181        to vary, making some of the tests fail. I have changed pcretest so that:
183        (a) When it is outputting text in the compiled version of a pattern, bytes
184            other than 32-126 are always shown as hex escapes.
186        (b) When it is outputting text that is a matched part of a subject string,
187            it does the same, unless a different locale has been set for the match
188            (using the /L modifier). In this case, it uses isprint() to decide.
190     4. Fixed a major bug that caused incorrect computation of the amount of memory
191        required for a compiled pattern when options that changed within the
192        pattern affected the logic of the preliminary scan that determines the
193        length. The relevant options are -x, and -i in UTF-8 mode. The result was
194        that the computed length was too small. The symptoms of this bug were
195        either the PCRE error "internal error: code overflow" from pcre_compile(),
196        or a glibc crash with a message such as "pcretest: free(): invalid next
197        size (fast)". Examples of patterns that provoked this bug (shown in
198        pcretest format) are:
200          /(?-x: )/x
201          /(?x)(?-x: \s*#\s*)/
202          /((?i)[\x{c0}])/8
203          /(?i:[\x{c0}])/8
205        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
206        is now done differently.
208     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
209        wrapper classes; (b) implement a new function in the C++ scanner that is
210        more efficient than the old way of doing things because it avoids levels of
211        recursion in the regex matching; (c) add a paragraph to the documentation
212        for the FullMatch() function.
214     6. The escape sequence \n was being treated as whatever was defined as
215        "newline". Not only was this contrary to the documentation, which states
216        that \n is character 10 (hex 0A), but it also went horribly wrong when
217        "newline" was defined as CRLF. This has been fixed.
219     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
220        was being set to -1 for the "end of line" case (supposedly a value that no
221        character can have). Though this value is never used (the check for end of
222        line is "zero bytes in current character"), it caused compiler complaints.
223        I've changed it to 0xffffffff.
225     8. In pcre_version.c, the version string was being built by a sequence of
226        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
227        string (as it is for production releases) called a macro with an empty
228        argument. The C standard says the result of this is undefined. The gcc
229        compiler treats it as an empty string (which was what was wanted) but it is
230        reported that Visual C gives an error. The source has been hacked around to
231        avoid this problem.
233     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
234        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
235        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
236        of them did).
238    10. Originally, pcretest opened its input and output without "b"; then I was
239        told that "b" was needed in some environments, so it was added for release
240        5.0 to both the input and output. (It makes no difference on Unix-like
241        systems.) Later I was told that it is wrong for the input on Windows. I've
242        now abstracted the modes into two macros, to make it easier to fiddle with
243        them, and removed "b" from the input mode under Windows.
245    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
247    12. Added -help and --help to pcretest as an official way of being reminded
248        of the options.
250    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
251        and pcrecpp.cc because they annoy compilers at high warning levels.
253    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
255    15. Fixed an occurrence of == in configure.ac that should have been = (shell
256        scripts are not C programs :-) and which was not noticed because it works
257        on Linux.
259    16. pcretest is supposed to handle any length of pattern and data line (as one
260        line or as a continued sequence of lines) by extending its input buffer if
261        necessary. This feature was broken for very long pattern lines, leading to
262        a string of junk being passed to pcre_compile() if the pattern was longer
263        than about 50K.
265    17. I have done a major re-factoring of the way pcre_compile() computes the
266        amount of memory needed for a compiled pattern. Previously, there was code
267        that made a preliminary scan of the pattern in order to do this. That was
268        OK when PCRE was new, but as the facilities have expanded, it has become
269        harder and harder to keep it in step with the real compile phase, and there
270        have been a number of bugs (see for example, 4 above). I have now found a
271        cunning way of running the real compile function in a "fake" mode that
272        enables it to compute how much memory it would need, while actually only
273        ever using a few hundred bytes of working memory and without too many
274        tests of the mode. This should make future maintenance and development
275        easier. A side effect of this work is that the limit of 200 on the nesting
276        depth of parentheses has been removed (though this was never a serious
277        limitation, I suspect). However, there is a downside: pcre_compile() now
278        runs more slowly than before (30% or more, depending on the pattern). I
279        hope this isn't a big issue. There is no effect on runtime performance.
281    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
282        newline (only possible for the last line of a file) and it was a
283        pattern that set a locale (followed by /Lsomething), pcretest crashed.
285    19. Added additional timing features to pcretest. (1) The -tm option now times
286        matching only, not compiling. (2) Both -t and -tm can be followed, as a
287        separate command line item, by a number that specifies the number of
288        repeats to use when timing. The default is 50000; this gives better
289        precision, but takes uncomfortably long for very large patterns.
291    20. Extended pcre_study() to be more clever in cases where a branch of a
292        subpattern has no definite first character. For example, (a*|b*)[cd] would
293        previously give no result from pcre_study(). Now it recognizes that the
294        first character must be a, b, c, or d.
296    21. There was an incorrect error "recursive call could loop indefinitely" if
297        a subpattern (or the entire pattern) that was being tested for matching an
298        empty string contained only one non-empty item after a nested subpattern.
299        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
300        incorrectly, because the \d was being skipped in the check.
302    22. The pcretest program now has a new pattern option /B and a command line
303        option -b, which is equivalent to adding /B to every pattern. This causes
304        it to show the compiled bytecode, without the additional information that
305        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
306        is the same as /B/I).
308    23. A new optimization is now able automatically to treat some sequences such
309        as a*b as a*+b. More specifically, if something simple (such as a character
310        or a simple class like \d) has an unlimited quantifier, and is followed by
311        something that cannot possibly match the quantified thing, the quantifier
312        is automatically "possessified".
314    24. A recursive reference to a subpattern whose number was greater than 39
315        went wrong under certain circumstances in UTF-8 mode. This bug could also
316        have affected the operation of pcre_study().
318    25. Realized that a little bit of performance could be had by replacing
319        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
321    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
323    27. Possessive quantifiers such as a++ were previously implemented by turning
324        them into atomic groups such as ($>a+). Now they have their own opcodes,
325        which improves performance. This includes the automatically created ones
326        from 23 above.
328    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
329        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
330        the first matched character to be a colon. This applied both to named and
331        numbered groups.
333    29. The ucpinternal.h header file was missing its idempotency #ifdef.
335    30. I was sent a "project" file called libpcre.a.dev which I understand makes
336        building PCRE on Windows easier, so I have included it in the distribution.
338    31. There is now a check in pcretest against a ridiculously large number being
339        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
340        loop, the loop is abandoned.
342    32. Forward references to subpatterns in conditions such as (?(2)...) where
343        subpattern 2 is defined later cause pcre_compile() to search forwards in
344        the pattern for the relevant set of parentheses. This search went wrong
345        when there were unescaped parentheses in a character class, parentheses
346        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
348    33. "Subroutine" calls and backreferences were previously restricted to
349        referencing subpatterns earlier in the regex. This restriction has now
350        been removed.
352    34. Added a number of extra features that are going to be in Perl 5.10. On the
353        whole, these are just syntactic alternatives for features that PCRE had
354        previously implemented using the Python syntax or my own invention. The
355        other formats are all retained for compatibility.
357        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
358            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
359            also .NET compatible.
361        (b) A recursion or subroutine call to a named group can now be defined as
362            (?&name) as well as (?P>name).
364        (c) A backreference to a named group can now be defined as \k<name> or
365            \k'name' as well as (?P=name). The new forms, as well as being in Perl
366            5.10, are also .NET compatible.
368        (d) A conditional reference to a named group can now use the syntax
369            (?(<name>) or (?('name') as well as (?(name).
371        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
372            groups (named and numbered) that are never evaluated inline, but can be
373            called as "subroutines" from elsewhere. In effect, the DEFINE condition
374            is always false. There may be only one alternative in such a group.
376        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
377            as the simple (?(R). The condition is true only if the most recent
378            recursion is that of the given number or name. It does not search out
379            through the entire recursion stack.
381        (g) The escape \gN or \g{N} has been added, where N is a positive or
382            negative number, specifying an absolute or relative reference.
384    35. Tidied to get rid of some further signed/unsigned compiler warnings and
385        some "unreachable code" warnings.
387    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
388        things, this adds five new scripts.
390    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
391        There were also incompatibilities regarding the handling of \Q..\E inside
392        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
393        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
395    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
396        matches an empty string, and forcibly breaks the loop. There were bugs in
397        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
398        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
399        separate and independent bugs (that affected different cases) have been
400        fixed.
402    39. Refactored the code to abolish the use of different opcodes for small
403        capturing bracket numbers. This is a tidy that I avoided doing when I
404        removed the limit on the number of capturing brackets for 3.5 back in 2001.
405        The new approach is not only tidier, it makes it possible to reduce the
406        memory needed to fix the previous bug (38).
408    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
409        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
410        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
411        mode.
413    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
414        report.
416    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
417        copy construction and assignment in the C++ wrapper.
419    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
420        couple of bugs that could have given wrong results in the "--newline=crlf"
421        case.
423    44. Added a number of casts and did some reorganization of signed/unsigned int
424        variables following suggestions from Dair Grant. Also renamed the variable
425        "this" as "item" because it is a C++ keyword.
427    45. Arranged for dftables to add
429          #include "pcre_internal.h"
431        to pcre_chartables.c because without it, gcc 4.x may remove the array
432        definition from the final binary if PCRE is built into a static library and
433        dead code stripping is activated.
435    46. For an unanchored pattern, if a match attempt fails at the start of a
436        newline sequence, and the newline setting is CRLF or ANY, and the next two
437        characters are CRLF, advance by two characters instead of one.
440    Version 6.7 04-Jul-06
441    ---------------------
443     1. In order to handle tests when input lines are enormously long, pcretest has
444        been re-factored so that it automatically extends its buffers when
445        necessary. The code is crude, but this _is_ just a test program. The
446        default size has been increased from 32K to 50K.
448     2. The code in pcre_study() was using the value of the re argument before
449        testing it for NULL. (Of course, in any sensible call of the function, it
450        won't be NULL.)
452     3. The memmove() emulation function in pcre_internal.h, which is used on
453        systems that lack both memmove() and bcopy() - that is, hardly ever -
454        was missing a "static" storage class specifier.
456     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
457        containing an extended class (one that cannot be represented by a bitmap
458        because it contains high-valued characters or Unicode property items, e.g.
459        [\pZ]). Almost always one would set UTF-8 mode when processing such a
460        pattern, but PCRE should not loop if you do not (it no longer does).
461        [Detail: two cases were found: (a) a repeated subpattern containing an
462        extended class; (b) a recursive reference to a subpattern that followed a
463        previous extended class. It wasn't skipping over the extended class
464        correctly when UTF-8 mode was not set.]
466     5. A negated single-character class was not being recognized as fixed-length
467        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
468        compile error "lookbehind assertion is not fixed length".
470     6. The RunPerlTest auxiliary script was showing an unexpected difference
471        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
472        write a Perl script that can interpret lines of an input file either as
473        byte characters or as UTF-8, which is what "perltest" was being required to
474        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
475        can't do is switch easily at run time between having the "use utf8;" pragma
476        or not. In the end, I fudged it by using the RunPerlTest script to insert
477        "use utf8;" explicitly for the UTF-8 tests.
479     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
480        the end of the subject string, contrary to the documentation and to what
481        Perl does. This was true of both matching functions. Now it matches only at
482        the start of the subject and immediately after *internal* newlines.
484     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
485        a pointer to an int instead of a pointer to an unsigned long int. This
486        caused problems on 64-bit systems.
488     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
489        instance of the 'standard' template library not being so standard".
491    10. There was no check on the number of named subpatterns nor the maximum
492        length of a subpattern name. The product of these values is used to compute
493        the size of the memory block for a compiled pattern. By supplying a very
494        long subpattern name and a large number of named subpatterns, the size
495        computation could be caused to overflow. This is now prevented by limiting
496        the length of names to 32 characters, and the number of named subpatterns
497        to 10,000.
499    11. Subpatterns that are repeated with specific counts have to be replicated in
500        the compiled pattern. The size of memory for this was computed from the
501        length of the subpattern and the repeat count. The latter is limited to
502        65535, but there was no limit on the former, meaning that integer overflow
503        could in principle occur. The compiled length of a repeated subpattern is
504        now limited to 30,000 bytes in order to prevent this.
506    12. Added the optional facility to have named substrings with the same name.
508    13. Added the ability to use a named substring as a condition, using the
509        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
510        are numbers (not recommended). Forward references are permitted.
512    14. Added forward references in named backreferences (if you see what I mean).
514    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
515        pattern could run off the end of the subject. For example, the pattern
516        "(?s)(.{1,5})"8 did this with the subject "ab".
518    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
519        PCRE_CASELESS was set when matching characters that were quantified with ?
520        or *.
522    17. A character class other than a single negated character that had a minimum
523        but no maximum quantifier - for example [ab]{6,} - was not handled
524        correctly by pce_dfa_exec(). It would match only one character.
526    18. A valid (though odd) pattern that looked like a POSIX character
527        class but used an invalid character after [ (for example [[,abc,]]) caused
528        pcre_compile() to give the error "Failed: internal error: code overflow" or
529        in some cases to crash with a glibc free() error. This could even happen if
530        the pattern terminated after [[ but there just happened to be a sequence of
531        letters, a binary zero, and a closing ] in the memory that followed.
533    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
534        over the years. Originally (before any Unicode support), just the bottom 8
535        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
536        output from "man perlunicode" includes this:
538          The regular expression compiler produces polymorphic opcodes.  That
539          is, the pattern adapts to the data and automatically switches to
540          the Unicode character scheme when presented with Unicode data--or
541          instead uses a traditional byte scheme when presented with byte
542          data.
544        Sadly, a wide octal escape does not cause a switch, and in a string with
545        no other multibyte characters, these octal escapes are treated as before.
546        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
547        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
548        Unicode string.
550        I have not perpetrated such confusion in PCRE. Up till now, it took just
551        the bottom 8 bits, as in old Perl. I have now made octal escapes with
552        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
553        translate to the appropriate multibyte character.
555    29. Applied some refactoring to reduce the number of warnings from Microsoft
556        and Borland compilers. This has included removing the fudge introduced
557        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
558        a warning about an unused variable.
560    21. PCRE has not included VT (character 0x0b) in the set of whitespace
561        characters since release 4.0, because Perl (from release 5.004) does not.
562        [Or at least, is documented not to: some releases seem to be in conflict
563        with the documentation.] However, when a pattern was studied with
564        pcre_study() and all its branches started with \s, PCRE still included VT
565        as a possible starting character. Of course, this did no harm; it just
566        caused an unnecessary match attempt.
568    22. Removed a now-redundant internal flag bit that recorded the fact that case
569        dependency changed within the pattern. This was once needed for "required
570        byte" processing, but is no longer used. This recovers a now-scarce options
571        bit. Also moved the least significant internal flag bit to the most-
572        significant bit of the word, which was not previously used (hangover from
573        the days when it was an int rather than a uint) to free up another bit for
574        the future.
576    23. Added support for CRLF line endings as well as CR and LF. As well as the
577        default being selectable at build time, it can now be changed at runtime
578        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
579        specify that it is scanning data with non-default line endings.
581    24. Changed the definition of CXXLINK to make it agree with the definition of
582        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
584    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
585        recursions. This makes a big different to stack usage for some patterns.
587    26. If a subpattern containing a named recursion or subroutine reference such
588        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
589        the space required for the compiled pattern went wrong and gave too small a
590        value. Depending on the environment, this could lead to "Failed: internal
591        error: code overflow at offset 49" or "glibc detected double free or
592        corruption" errors.
594    27. Applied patches from Google (a) to support the new newline modes and (b) to
595        advance over multibyte UTF-8 characters in GlobalReplace.
597    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
598        difference for some implementation of PCRE in some Windows version.
600    29. Added some extra testing facilities to pcretest:
602        \q<number>   in a data line sets the "match limit" value
603        \Q<number>   in a data line sets the "match recursion limt" value
604        -S <number>  sets the stack size, where <number> is in megabytes
606        The -S option isn't available for Windows.
609    Version 6.6 06-Feb-06
610    ---------------------
612     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
613        in pcreposix.h. I have copied the definition from pcre.h.
615     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
616        because pcre.h is no longer a built file.
618     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
619        not normally included in the compiled code.
622    Version 6.5 01-Feb-06
623    ---------------------
625     1. When using the partial match feature with pcre_dfa_exec(), it was not
626        anchoring the second and subsequent partial matches at the new starting
627        point. This could lead to incorrect results. For example, with the pattern
628        /1234/, partially matching against "123" and then "a4" gave a match.
630     2. Changes to pcregrep:
632        (a) All non-match returns from pcre_exec() were being treated as failures
633            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
634            error message is output. Some extra information is given for the
635            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
636            probably the only errors that are likely to be caused by users (by
637            specifying a regex that has nested indefinite repeats, for instance).
638            If there are more than 20 of these errors, pcregrep is abandoned.
640        (b) A binary zero was treated as data while matching, but terminated the
641            output line if it was written out. This has been fixed: binary zeroes
642            are now no different to any other data bytes.
644        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
645            used to set a locale for matching. The --locale=xxxx long option has
646            been added (no short equivalent) to specify a locale explicitly on the
647            pcregrep command, overriding the environment variables.
649        (d) When -B was used with -n, some line numbers in the output were one less
650            than they should have been.
652        (e) Added the -o (--only-matching) option.
654        (f) If -A or -C was used with -c (count only), some lines of context were
655            accidentally printed for the final match.
657        (g) Added the -H (--with-filename) option.
659        (h) The combination of options -rh failed to suppress file names for files
660            that were found from directory arguments.
662        (i) Added the -D (--devices) and -d (--directories) options.
664        (j) Added the -F (--fixed-strings) option.
666        (k) Allow "-" to be used as a file name for -f as well as for a data file.
668        (l) Added the --colo(u)r option.
670        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
671            is not present by default.
673     3. A nasty bug was discovered in the handling of recursive patterns, that is,
674        items such as (?R) or (?1), when the recursion could match a number of
675        alternatives. If it matched one of the alternatives, but subsequently,
676        outside the recursion, there was a failure, the code tried to back up into
677        the recursion. However, because of the way PCRE is implemented, this is not
678        possible, and the result was an incorrect result from the match.
680        In order to prevent this happening, the specification of recursion has
681        been changed so that all such subpatterns are automatically treated as
682        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
684     4. I had overlooked the fact that, in some locales, there are characters for
685        which isalpha() is true but neither isupper() nor islower() are true. In
686        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
687        and ordfeminine) are like this. This affected the treatment of \w and \W
688        when they appeared in character classes, but not when they appeared outside
689        a character class. The bit map for "word" characters is now created
690        separately from the results of isalnum() instead of just taking it from the
691        upper, lower, and digit maps. (Plus the underscore character, of course.)
693     5. The above bug also affected the handling of POSIX character classes such as
694        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
695        permanent tables. Instead, the bit maps for such a class were previously
696        created as the appropriate unions of the upper, lower, and digit bitmaps.
697        Now they are created by subtraction from the [[:word:]] class, which has
698        its own bitmap.
700     6. The [[:blank:]] character class matches horizontal, but not vertical space.
701        It is created by subtracting the vertical space characters (\x09, \x0a,
702        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
703        subtraction was done in the overall bitmap for a character class, meaning
704        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
705        be recognized. This bug has been fixed.
707     7. Patches from the folks at Google:
709          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
710          real life, but is still worth protecting against".
712          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
713          regular expressions".
715          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
716          have it.
718          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
719          "configure" and the latter not, in order to fix a problem somebody had
720          with compiling the Arg class on HP-UX.
722          (e) Improve the error-handling of the C++ wrapper a little bit.
724          (f) New tests for checking recursion limiting.
726     8. The pcre_memmove() function, which is used only if the environment does not
727        have a standard memmove() function (and is therefore rarely compiled),
728        contained two bugs: (a) use of int instead of size_t, and (b) it was not
729        returning a result (though PCRE never actually uses the result).
731     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
732        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
733        returned instead of calling malloc() with an overflowing number that would
734        most likely cause subsequent chaos.
736    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
738    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
739        with this option is matched, the nmatch and pmatch options of regexec() are
740        ignored.
742    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
743        provided in case anyone wants to the the POSIX interface with UTF-8
744        strings.
746    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
747        C++ linking (needed for some HP-UX environments).
749    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
750        (unused parameter) and in the pcre_printint() function (omitted "default"
751        switch label when the default is to do nothing).
753    15. Added some code to make it possible, when PCRE is compiled as a C++
754        library, to replace subject pointers for pcre_exec() with a smart pointer
755        class, thus making it possible to process discontinuous strings.
757    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
758        much the same function. They were added by different people who were trying
759        to make PCRE easy to compile on non-Unix systems. It has been suggested
760        that PCRE_EXPORT be abolished now that there is more automatic apparatus
761        for compiling on Windows systems. I have therefore replaced it with
762        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
763        defaults to "extern" for C or "extern C" for C++, which works fine on
764        Unix-like systems. It is now possible to override the value of PCRE_DATA_
765        SCOPE with something explicit in config.h. In addition:
767        (a) pcreposix.h still had just "extern" instead of either of these macros;
768            I have replaced it with PCRE_DATA_SCOPE.
770        (b) Functions such as _pcre_xclass(), which are internal to the library,
771            but external in the C sense, all had PCRE_EXPORT in their definitions.
772            This is apparently wrong for the Windows case, so I have removed it.
773            (It makes no difference on Unix-like systems.)
775    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
776        of recursive calls to match(). This is different to MATCH_LIMIT because
777        that limits the total number of calls to match(), not all of which increase
778        the depth of recursion. Limiting the recursion depth limits the amount of
779        stack (or heap if NO_RECURSE is set) that is used. The default can be set
780        when PCRE is compiled, and changed at run time. A patch from Google adds
781        this functionality to the C++ interface.
783    18. Changes to the handling of Unicode character properties:
785        (a) Updated the table to Unicode 4.1.0.
787        (b) Recognize characters that are not in the table as "Cn" (undefined).
789        (c) I revised the way the table is implemented to a much improved format
790            which includes recognition of ranges. It now supports the ranges that
791            are defined in UnicodeData.txt, and it also amalgamates other
792            characters into ranges. This has reduced the number of entries in the
793            table from around 16,000 to around 3,000, thus reducing its size
794            considerably. I realized I did not need to use a tree structure after
795            all - a binary chop search is just as efficient. Having reduced the
796            number of entries, I extended their size from 6 bytes to 8 bytes to
797            allow for more data.
799        (d) Added support for Unicode script names via properties such as \p{Han}.
801    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
802        matching that character.
804    20. When matching a repeated Unicode property with a minimum greater than zero,
805        (for example \pL{2,}), PCRE could look past the end of the subject if it
806        reached it while seeking the minimum number of characters. This could
807        happen only if some of the characters were more than one byte long, because
808        there is a check for at least the minimum number of bytes.
810    21. Refactored the implementation of \p and \P so as to be more general, to
811        allow for more different types of property in future. This has changed the
812        compiled form incompatibly. Anybody with saved compiled patterns that use
813        \p or \P will have to recompile them.
815    22. Added "Any" and "L&" to the supported property types.
817    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
818        but give a compile time error if the value is greater than 0xff.
820    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
821        accidentally not being installed or uninstalled.
823    25. The pcre.h file was built from pcre.h.in, but the only changes that were
824        made were to insert the current release number. This seemed silly, because
825        it made things harder for people building PCRE on systems that don't run
826        "configure". I have turned pcre.h into a distributed file, no longer built
827        by "configure", with the version identification directly included. There is
828        no longer a pcre.h.in file.
830        However, this change necessitated a change to the pcre-config script as
831        well. It is built from pcre-config.in, and one of the substitutions was the
832        release number. I have updated configure.ac so that ./configure now finds
833        the release number by grepping pcre.h.
835    26. Added the ability to run the tests under valgrind.
838    Version 6.4 05-Sep-05
839    ---------------------
841     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
842        "--" to be printed when multiple files were scanned, even when none of the
843        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
844        consider it to be a bug, and have restored the previous behaviour.
846     2. A couple of code tidies to get rid of compiler warnings.
848     3. The pcretest program used to cheat by referring to symbols in the library
849        whose names begin with _pcre_. These are internal symbols that are not
850        really supposed to be visible externally, and in some environments it is
851        possible to suppress them. The cheating is now confined to including
852        certain files from the library's source, which is a bit cleaner.
854     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
855        file's purpose clearer.
857     5. Reorganized pcre_ucp_findchar().
860  Version 6.3 15-Aug-05  Version 6.3 15-Aug-05
861  ---------------------  ---------------------

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