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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.
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.
21    Version 7.1 24-Apr-07
22    ---------------------
24     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
25        that is more "standard", making use of automake and other Autotools. There
26        is some re-arrangement of the files and adjustment of comments consequent
27        on this.
29     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
30        for recursive directory scanning broke on some systems because the files
31        are not scanned in any specific order and on different systems the order
32        was different. A call to "sort" has been inserted into RunGrepTest for the
33        approprate test as a short-term fix. In the longer term there may be an
34        alternative.
36     3. I had an email from Eric Raymond about problems translating some of PCRE's
37        man pages to HTML (despite the fact that I distribute HTML pages, some
38        people do their own conversions for various reasons). The problems
39        concerned the use of low-level troff macros .br and .in. I have therefore
40        removed all such uses from the man pages (some were redundant, some could
41        be replaced by .nf/.fi pairs). The 132html script that I use to generate
42        HTML has been updated to handle .nf/.fi and to complain if it encounters
43        .br or .in.
45     4. Updated comments in configure.ac that get placed in config.h.in and also
46        arranged for config.h to be included in the distribution, with the name
47        config.h.generic, for the benefit of those who have to compile without
48        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
50     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
51        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
52        makevp.bat for the current PCRE, using the additional files
53        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
55     6. A Windows user reported a minor discrepancy with test 2, which turned out
56        to be caused by a trailing space on an input line that had got lost in his
57        copy. The trailing space was an accident, so I've just removed it.
59     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
60        that is needed.
62     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
63        as "const" (a) because they are and (b) because it helps the PHP
64        maintainers who have recently made a script to detect big data structures
65        in the php code that should be moved to the .rodata section. I remembered
66        to update Builducptable as well, so it won't revert if ucptable.h is ever
67        re-created.
69     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
70        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
71        order to be able to cut out the UTF-8 tables in the latter when UTF-8
72        support is not required. This saves 1.5-2K of code, which is important in
73        some applications.
75        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
76        so as not to refer to the tables, even though these functions will never be
77        called when UTF-8 support is disabled. Otherwise there are problems with a
78        shared library.
80    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
82        (a) It was defining its arguments as char * instead of void *.
84        (b) It was assuming that all moves were upwards in memory; this was true
85            a long time ago when I wrote it, but is no longer the case.
87        The emulated memove() is provided for those environments that have neither
88        memmove() nor bcopy(). I didn't think anyone used it these days, but that
89        is clearly not the case, as these two bugs were recently reported.
91    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
92        and Detrail to create the HTML documentation, the .txt form of the man
93        pages, and it removes trailing spaces from listed files. It also creates
94        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
95        case, it wraps all the #defines with #ifndefs. This script should be run
96        before "make dist".
98    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
99        with Unicode property support.
101        (a) For a maximizing quantifier, if the two different cases of the
102            character were of different lengths in their UTF-8 codings (there are
103            some cases like this - I found 11), and the matching function had to
104            back up over a mixture of the two cases, it incorrectly assumed they
105            were both the same length.
107        (b) When PCRE was configured to use the heap rather than the stack for
108            recursion during matching, it was not correctly preserving the data for
109            the other case of a UTF-8 character when checking ahead for a match
110            while processing a minimizing repeat. If the check also involved
111            matching a wide character, but failed, corruption could cause an
112            erroneous result when trying to check for a repeat of the original
113            character.
115    13. Some tidying changes to the testing mechanism:
117        (a) The RunTest script now detects the internal link size and whether there
118            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
119            values substituted by "configure". (The RunGrepTest script already did
120            this for UTF-8.) The configure.ac script no longer substitutes the
121            relevant variables.
123        (b) The debugging options /B and /D in pcretest show the compiled bytecode
124            with length and offset values. This means that the output is different
125            for different internal link sizes. Test 2 is skipped for link sizes
126            other than 2 because of this, bypassing the problem. Unfortunately,
127            there was also a test in test 3 (the locale tests) that used /B and
128            failed for link sizes other than 2. Rather than cut the whole test out,
129            I have added a new /Z option to pcretest that replaces the length and
130            offset values with spaces. This is now used to make test 3 independent
131            of link size. (Test 2 will be tidied up later.)
133    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
134        segmentation fault instead of returning the appropriate error message.
136    15. In multiline mode when the newline sequence was set to "any", the pattern
137        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
138        This doesn't seem right; it now treats the CRLF combination as the line
139        ending, and so does not match in that case. It's only a pattern such as ^$
140        that would hit this one: something like ^ABC$ would have failed after \r
141        and then tried again after \r\n.
143    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
144        in an attempt to make files that differ only in their line terminators
145        compare equal. This works on Linux.
147    17. Under certain error circumstances pcregrep might try to free random memory
148        as it exited. This is now fixed, thanks to valgrind.
150    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
151        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
152        was because its rules for how to advance for /g after matching an empty
153        string at the end of a line did not allow for this case. They now check for
154        it specially.
156    20. pcretest is supposed to handle patterns and data of any length, by
157        extending its buffers when necessary. It was getting this wrong when the
158        buffer for a data line had to be extended.
160    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
161        CRLF as a newline sequence.
163    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
164        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
165        I have nevertheless tidied it up.
167    23. Added some casts to kill warnings from HP-UX ia64 compiler.
169    24. Added a man page for pcre-config.
172    Version 7.0 19-Dec-06
173    ---------------------
175     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
176        moving to gcc 4.1.1.
178     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
179        sys/time.h, which is documented as needed for this function. It doesn't
180        seem to matter on Linux, but it showed up on some releases of OS X.
182     3. It seems that there are systems where bytes whose values are greater than
183        127 match isprint() in the "C" locale. The "C" locale should be the
184        default when a C program starts up. In most systems, only ASCII printing
185        characters match isprint(). This difference caused the output from pcretest
186        to vary, making some of the tests fail. I have changed pcretest so that:
188        (a) When it is outputting text in the compiled version of a pattern, bytes
189            other than 32-126 are always shown as hex escapes.
191        (b) When it is outputting text that is a matched part of a subject string,
192            it does the same, unless a different locale has been set for the match
193            (using the /L modifier). In this case, it uses isprint() to decide.
195     4. Fixed a major bug that caused incorrect computation of the amount of memory
196        required for a compiled pattern when options that changed within the
197        pattern affected the logic of the preliminary scan that determines the
198        length. The relevant options are -x, and -i in UTF-8 mode. The result was
199        that the computed length was too small. The symptoms of this bug were
200        either the PCRE error "internal error: code overflow" from pcre_compile(),
201        or a glibc crash with a message such as "pcretest: free(): invalid next
202        size (fast)". Examples of patterns that provoked this bug (shown in
203        pcretest format) are:
205          /(?-x: )/x
206          /(?x)(?-x: \s*#\s*)/
207          /((?i)[\x{c0}])/8
208          /(?i:[\x{c0}])/8
210        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
211        is now done differently.
213     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
214        wrapper classes; (b) implement a new function in the C++ scanner that is
215        more efficient than the old way of doing things because it avoids levels of
216        recursion in the regex matching; (c) add a paragraph to the documentation
217        for the FullMatch() function.
219     6. The escape sequence \n was being treated as whatever was defined as
220        "newline". Not only was this contrary to the documentation, which states
221        that \n is character 10 (hex 0A), but it also went horribly wrong when
222        "newline" was defined as CRLF. This has been fixed.
224     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
225        was being set to -1 for the "end of line" case (supposedly a value that no
226        character can have). Though this value is never used (the check for end of
227        line is "zero bytes in current character"), it caused compiler complaints.
228        I've changed it to 0xffffffff.
230     8. In pcre_version.c, the version string was being built by a sequence of
231        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
232        string (as it is for production releases) called a macro with an empty
233        argument. The C standard says the result of this is undefined. The gcc
234        compiler treats it as an empty string (which was what was wanted) but it is
235        reported that Visual C gives an error. The source has been hacked around to
236        avoid this problem.
238     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
239        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
240        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
241        of them did).
243    10. Originally, pcretest opened its input and output without "b"; then I was
244        told that "b" was needed in some environments, so it was added for release
245        5.0 to both the input and output. (It makes no difference on Unix-like
246        systems.) Later I was told that it is wrong for the input on Windows. I've
247        now abstracted the modes into two macros, to make it easier to fiddle with
248        them, and removed "b" from the input mode under Windows.
250    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
252    12. Added -help and --help to pcretest as an official way of being reminded
253        of the options.
255    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
256        and pcrecpp.cc because they annoy compilers at high warning levels.
258    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
260    15. Fixed an occurrence of == in configure.ac that should have been = (shell
261        scripts are not C programs :-) and which was not noticed because it works
262        on Linux.
264    16. pcretest is supposed to handle any length of pattern and data line (as one
265        line or as a continued sequence of lines) by extending its input buffer if
266        necessary. This feature was broken for very long pattern lines, leading to
267        a string of junk being passed to pcre_compile() if the pattern was longer
268        than about 50K.
270    17. I have done a major re-factoring of the way pcre_compile() computes the
271        amount of memory needed for a compiled pattern. Previously, there was code
272        that made a preliminary scan of the pattern in order to do this. That was
273        OK when PCRE was new, but as the facilities have expanded, it has become
274        harder and harder to keep it in step with the real compile phase, and there
275        have been a number of bugs (see for example, 4 above). I have now found a
276        cunning way of running the real compile function in a "fake" mode that
277        enables it to compute how much memory it would need, while actually only
278        ever using a few hundred bytes of working memory and without too many
279        tests of the mode. This should make future maintenance and development
280        easier. A side effect of this work is that the limit of 200 on the nesting
281        depth of parentheses has been removed (though this was never a serious
282        limitation, I suspect). However, there is a downside: pcre_compile() now
283        runs more slowly than before (30% or more, depending on the pattern). I
284        hope this isn't a big issue. There is no effect on runtime performance.
286    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
287        newline (only possible for the last line of a file) and it was a
288        pattern that set a locale (followed by /Lsomething), pcretest crashed.
290    19. Added additional timing features to pcretest. (1) The -tm option now times
291        matching only, not compiling. (2) Both -t and -tm can be followed, as a
292        separate command line item, by a number that specifies the number of
293        repeats to use when timing. The default is 50000; this gives better
294        precision, but takes uncomfortably long for very large patterns.
296    20. Extended pcre_study() to be more clever in cases where a branch of a
297        subpattern has no definite first character. For example, (a*|b*)[cd] would
298        previously give no result from pcre_study(). Now it recognizes that the
299        first character must be a, b, c, or d.
301    21. There was an incorrect error "recursive call could loop indefinitely" if
302        a subpattern (or the entire pattern) that was being tested for matching an
303        empty string contained only one non-empty item after a nested subpattern.
304        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
305        incorrectly, because the \d was being skipped in the check.
307    22. The pcretest program now has a new pattern option /B and a command line
308        option -b, which is equivalent to adding /B to every pattern. This causes
309        it to show the compiled bytecode, without the additional information that
310        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
311        is the same as /B/I).
313    23. A new optimization is now able automatically to treat some sequences such
314        as a*b as a*+b. More specifically, if something simple (such as a character
315        or a simple class like \d) has an unlimited quantifier, and is followed by
316        something that cannot possibly match the quantified thing, the quantifier
317        is automatically "possessified".
319    24. A recursive reference to a subpattern whose number was greater than 39
320        went wrong under certain circumstances in UTF-8 mode. This bug could also
321        have affected the operation of pcre_study().
323    25. Realized that a little bit of performance could be had by replacing
324        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
326    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
328    27. Possessive quantifiers such as a++ were previously implemented by turning
329        them into atomic groups such as ($>a+). Now they have their own opcodes,
330        which improves performance. This includes the automatically created ones
331        from 23 above.
333    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
334        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
335        the first matched character to be a colon. This applied both to named and
336        numbered groups.
338    29. The ucpinternal.h header file was missing its idempotency #ifdef.
340    30. I was sent a "project" file called libpcre.a.dev which I understand makes
341        building PCRE on Windows easier, so I have included it in the distribution.
343    31. There is now a check in pcretest against a ridiculously large number being
344        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
345        loop, the loop is abandoned.
347    32. Forward references to subpatterns in conditions such as (?(2)...) where
348        subpattern 2 is defined later cause pcre_compile() to search forwards in
349        the pattern for the relevant set of parentheses. This search went wrong
350        when there were unescaped parentheses in a character class, parentheses
351        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
353    33. "Subroutine" calls and backreferences were previously restricted to
354        referencing subpatterns earlier in the regex. This restriction has now
355        been removed.
357    34. Added a number of extra features that are going to be in Perl 5.10. On the
358        whole, these are just syntactic alternatives for features that PCRE had
359        previously implemented using the Python syntax or my own invention. The
360        other formats are all retained for compatibility.
362        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
363            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
364            also .NET compatible.
366        (b) A recursion or subroutine call to a named group can now be defined as
367            (?&name) as well as (?P>name).
369        (c) A backreference to a named group can now be defined as \k<name> or
370            \k'name' as well as (?P=name). The new forms, as well as being in Perl
371            5.10, are also .NET compatible.
373        (d) A conditional reference to a named group can now use the syntax
374            (?(<name>) or (?('name') as well as (?(name).
376        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
377            groups (named and numbered) that are never evaluated inline, but can be
378            called as "subroutines" from elsewhere. In effect, the DEFINE condition
379            is always false. There may be only one alternative in such a group.
381        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
382            as the simple (?(R). The condition is true only if the most recent
383            recursion is that of the given number or name. It does not search out
384            through the entire recursion stack.
386        (g) The escape \gN or \g{N} has been added, where N is a positive or
387            negative number, specifying an absolute or relative reference.
389    35. Tidied to get rid of some further signed/unsigned compiler warnings and
390        some "unreachable code" warnings.
392    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
393        things, this adds five new scripts.
395    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
396        There were also incompatibilities regarding the handling of \Q..\E inside
397        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
398        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
400    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
401        matches an empty string, and forcibly breaks the loop. There were bugs in
402        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
403        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
404        separate and independent bugs (that affected different cases) have been
405        fixed.
407    39. Refactored the code to abolish the use of different opcodes for small
408        capturing bracket numbers. This is a tidy that I avoided doing when I
409        removed the limit on the number of capturing brackets for 3.5 back in 2001.
410        The new approach is not only tidier, it makes it possible to reduce the
411        memory needed to fix the previous bug (38).
413    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
414        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
415        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
416        mode.
418    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
419        report.
421    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
422        copy construction and assignment in the C++ wrapper.
424    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
425        couple of bugs that could have given wrong results in the "--newline=crlf"
426        case.
428    44. Added a number of casts and did some reorganization of signed/unsigned int
429        variables following suggestions from Dair Grant. Also renamed the variable
430        "this" as "item" because it is a C++ keyword.
432    45. Arranged for dftables to add
434          #include "pcre_internal.h"
436        to pcre_chartables.c because without it, gcc 4.x may remove the array
437        definition from the final binary if PCRE is built into a static library and
438        dead code stripping is activated.
440    46. For an unanchored pattern, if a match attempt fails at the start of a
441        newline sequence, and the newline setting is CRLF or ANY, and the next two
442        characters are CRLF, advance by two characters instead of one.
445    Version 6.7 04-Jul-06
446    ---------------------
448     1. In order to handle tests when input lines are enormously long, pcretest has
449        been re-factored so that it automatically extends its buffers when
450        necessary. The code is crude, but this _is_ just a test program. The
451        default size has been increased from 32K to 50K.
453     2. The code in pcre_study() was using the value of the re argument before
454        testing it for NULL. (Of course, in any sensible call of the function, it
455        won't be NULL.)
457     3. The memmove() emulation function in pcre_internal.h, which is used on
458        systems that lack both memmove() and bcopy() - that is, hardly ever -
459        was missing a "static" storage class specifier.
461     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
462        containing an extended class (one that cannot be represented by a bitmap
463        because it contains high-valued characters or Unicode property items, e.g.
464        [\pZ]). Almost always one would set UTF-8 mode when processing such a
465        pattern, but PCRE should not loop if you do not (it no longer does).
466        [Detail: two cases were found: (a) a repeated subpattern containing an
467        extended class; (b) a recursive reference to a subpattern that followed a
468        previous extended class. It wasn't skipping over the extended class
469        correctly when UTF-8 mode was not set.]
471     5. A negated single-character class was not being recognized as fixed-length
472        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
473        compile error "lookbehind assertion is not fixed length".
475     6. The RunPerlTest auxiliary script was showing an unexpected difference
476        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
477        write a Perl script that can interpret lines of an input file either as
478        byte characters or as UTF-8, which is what "perltest" was being required to
479        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
480        can't do is switch easily at run time between having the "use utf8;" pragma
481        or not. In the end, I fudged it by using the RunPerlTest script to insert
482        "use utf8;" explicitly for the UTF-8 tests.
484     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
485        the end of the subject string, contrary to the documentation and to what
486        Perl does. This was true of both matching functions. Now it matches only at
487        the start of the subject and immediately after *internal* newlines.
489     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
490        a pointer to an int instead of a pointer to an unsigned long int. This
491        caused problems on 64-bit systems.
493     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
494        instance of the 'standard' template library not being so standard".
496    10. There was no check on the number of named subpatterns nor the maximum
497        length of a subpattern name. The product of these values is used to compute
498        the size of the memory block for a compiled pattern. By supplying a very
499        long subpattern name and a large number of named subpatterns, the size
500        computation could be caused to overflow. This is now prevented by limiting
501        the length of names to 32 characters, and the number of named subpatterns
502        to 10,000.
504    11. Subpatterns that are repeated with specific counts have to be replicated in
505        the compiled pattern. The size of memory for this was computed from the
506        length of the subpattern and the repeat count. The latter is limited to
507        65535, but there was no limit on the former, meaning that integer overflow
508        could in principle occur. The compiled length of a repeated subpattern is
509        now limited to 30,000 bytes in order to prevent this.
511    12. Added the optional facility to have named substrings with the same name.
513    13. Added the ability to use a named substring as a condition, using the
514        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
515        are numbers (not recommended). Forward references are permitted.
517    14. Added forward references in named backreferences (if you see what I mean).
519    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
520        pattern could run off the end of the subject. For example, the pattern
521        "(?s)(.{1,5})"8 did this with the subject "ab".
523    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
524        PCRE_CASELESS was set when matching characters that were quantified with ?
525        or *.
527    17. A character class other than a single negated character that had a minimum
528        but no maximum quantifier - for example [ab]{6,} - was not handled
529        correctly by pce_dfa_exec(). It would match only one character.
531    18. A valid (though odd) pattern that looked like a POSIX character
532        class but used an invalid character after [ (for example [[,abc,]]) caused
533        pcre_compile() to give the error "Failed: internal error: code overflow" or
534        in some cases to crash with a glibc free() error. This could even happen if
535        the pattern terminated after [[ but there just happened to be a sequence of
536        letters, a binary zero, and a closing ] in the memory that followed.
538    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
539        over the years. Originally (before any Unicode support), just the bottom 8
540        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
541        output from "man perlunicode" includes this:
543          The regular expression compiler produces polymorphic opcodes.  That
544          is, the pattern adapts to the data and automatically switches to
545          the Unicode character scheme when presented with Unicode data--or
546          instead uses a traditional byte scheme when presented with byte
547          data.
549        Sadly, a wide octal escape does not cause a switch, and in a string with
550        no other multibyte characters, these octal escapes are treated as before.
551        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
552        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
553        Unicode string.
555        I have not perpetrated such confusion in PCRE. Up till now, it took just
556        the bottom 8 bits, as in old Perl. I have now made octal escapes with
557        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
558        translate to the appropriate multibyte character.
560    29. Applied some refactoring to reduce the number of warnings from Microsoft
561        and Borland compilers. This has included removing the fudge introduced
562        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
563        a warning about an unused variable.
565    21. PCRE has not included VT (character 0x0b) in the set of whitespace
566        characters since release 4.0, because Perl (from release 5.004) does not.
567        [Or at least, is documented not to: some releases seem to be in conflict
568        with the documentation.] However, when a pattern was studied with
569        pcre_study() and all its branches started with \s, PCRE still included VT
570        as a possible starting character. Of course, this did no harm; it just
571        caused an unnecessary match attempt.
573    22. Removed a now-redundant internal flag bit that recorded the fact that case
574        dependency changed within the pattern. This was once needed for "required
575        byte" processing, but is no longer used. This recovers a now-scarce options
576        bit. Also moved the least significant internal flag bit to the most-
577        significant bit of the word, which was not previously used (hangover from
578        the days when it was an int rather than a uint) to free up another bit for
579        the future.
581    23. Added support for CRLF line endings as well as CR and LF. As well as the
582        default being selectable at build time, it can now be changed at runtime
583        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
584        specify that it is scanning data with non-default line endings.
586    24. Changed the definition of CXXLINK to make it agree with the definition of
587        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
589    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
590        recursions. This makes a big different to stack usage for some patterns.
592    26. If a subpattern containing a named recursion or subroutine reference such
593        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
594        the space required for the compiled pattern went wrong and gave too small a
595        value. Depending on the environment, this could lead to "Failed: internal
596        error: code overflow at offset 49" or "glibc detected double free or
597        corruption" errors.
599    27. Applied patches from Google (a) to support the new newline modes and (b) to
600        advance over multibyte UTF-8 characters in GlobalReplace.
602    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
603        difference for some implementation of PCRE in some Windows version.
605    29. Added some extra testing facilities to pcretest:
607        \q<number>   in a data line sets the "match limit" value
608        \Q<number>   in a data line sets the "match recursion limt" value
609        -S <number>  sets the stack size, where <number> is in megabytes
611        The -S option isn't available for Windows.
614    Version 6.6 06-Feb-06
615    ---------------------
617     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
618        in pcreposix.h. I have copied the definition from pcre.h.
620     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
621        because pcre.h is no longer a built file.
623     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
624        not normally included in the compiled code.
627    Version 6.5 01-Feb-06
628    ---------------------
630     1. When using the partial match feature with pcre_dfa_exec(), it was not
631        anchoring the second and subsequent partial matches at the new starting
632        point. This could lead to incorrect results. For example, with the pattern
633        /1234/, partially matching against "123" and then "a4" gave a match.
635     2. Changes to pcregrep:
637        (a) All non-match returns from pcre_exec() were being treated as failures
638            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
639            error message is output. Some extra information is given for the
640            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
641            probably the only errors that are likely to be caused by users (by
642            specifying a regex that has nested indefinite repeats, for instance).
643            If there are more than 20 of these errors, pcregrep is abandoned.
645        (b) A binary zero was treated as data while matching, but terminated the
646            output line if it was written out. This has been fixed: binary zeroes
647            are now no different to any other data bytes.
649        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
650            used to set a locale for matching. The --locale=xxxx long option has
651            been added (no short equivalent) to specify a locale explicitly on the
652            pcregrep command, overriding the environment variables.
654        (d) When -B was used with -n, some line numbers in the output were one less
655            than they should have been.
657        (e) Added the -o (--only-matching) option.
659        (f) If -A or -C was used with -c (count only), some lines of context were
660            accidentally printed for the final match.
662        (g) Added the -H (--with-filename) option.
664        (h) The combination of options -rh failed to suppress file names for files
665            that were found from directory arguments.
667        (i) Added the -D (--devices) and -d (--directories) options.
669        (j) Added the -F (--fixed-strings) option.
671        (k) Allow "-" to be used as a file name for -f as well as for a data file.
673        (l) Added the --colo(u)r option.
675        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
676            is not present by default.
678     3. A nasty bug was discovered in the handling of recursive patterns, that is,
679        items such as (?R) or (?1), when the recursion could match a number of
680        alternatives. If it matched one of the alternatives, but subsequently,
681        outside the recursion, there was a failure, the code tried to back up into
682        the recursion. However, because of the way PCRE is implemented, this is not
683        possible, and the result was an incorrect result from the match.
685        In order to prevent this happening, the specification of recursion has
686        been changed so that all such subpatterns are automatically treated as
687        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
689     4. I had overlooked the fact that, in some locales, there are characters for
690        which isalpha() is true but neither isupper() nor islower() are true. In
691        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
692        and ordfeminine) are like this. This affected the treatment of \w and \W
693        when they appeared in character classes, but not when they appeared outside
694        a character class. The bit map for "word" characters is now created
695        separately from the results of isalnum() instead of just taking it from the
696        upper, lower, and digit maps. (Plus the underscore character, of course.)
698     5. The above bug also affected the handling of POSIX character classes such as
699        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
700        permanent tables. Instead, the bit maps for such a class were previously
701        created as the appropriate unions of the upper, lower, and digit bitmaps.
702        Now they are created by subtraction from the [[:word:]] class, which has
703        its own bitmap.
705     6. The [[:blank:]] character class matches horizontal, but not vertical space.
706        It is created by subtracting the vertical space characters (\x09, \x0a,
707        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
708        subtraction was done in the overall bitmap for a character class, meaning
709        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
710        be recognized. This bug has been fixed.
712     7. Patches from the folks at Google:
714          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
715          real life, but is still worth protecting against".
717          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
718          regular expressions".
720          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
721          have it.
723          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
724          "configure" and the latter not, in order to fix a problem somebody had
725          with compiling the Arg class on HP-UX.
727          (e) Improve the error-handling of the C++ wrapper a little bit.
729          (f) New tests for checking recursion limiting.
731     8. The pcre_memmove() function, which is used only if the environment does not
732        have a standard memmove() function (and is therefore rarely compiled),
733        contained two bugs: (a) use of int instead of size_t, and (b) it was not
734        returning a result (though PCRE never actually uses the result).
736     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
737        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
738        returned instead of calling malloc() with an overflowing number that would
739        most likely cause subsequent chaos.
741    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
743    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
744        with this option is matched, the nmatch and pmatch options of regexec() are
745        ignored.
747    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
748        provided in case anyone wants to the the POSIX interface with UTF-8
749        strings.
751    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
752        C++ linking (needed for some HP-UX environments).
754    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
755        (unused parameter) and in the pcre_printint() function (omitted "default"
756        switch label when the default is to do nothing).
758    15. Added some code to make it possible, when PCRE is compiled as a C++
759        library, to replace subject pointers for pcre_exec() with a smart pointer
760        class, thus making it possible to process discontinuous strings.
762    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
763        much the same function. They were added by different people who were trying
764        to make PCRE easy to compile on non-Unix systems. It has been suggested
765        that PCRE_EXPORT be abolished now that there is more automatic apparatus
766        for compiling on Windows systems. I have therefore replaced it with
767        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
768        defaults to "extern" for C or "extern C" for C++, which works fine on
769        Unix-like systems. It is now possible to override the value of PCRE_DATA_
770        SCOPE with something explicit in config.h. In addition:
772        (a) pcreposix.h still had just "extern" instead of either of these macros;
773            I have replaced it with PCRE_DATA_SCOPE.
775        (b) Functions such as _pcre_xclass(), which are internal to the library,
776            but external in the C sense, all had PCRE_EXPORT in their definitions.
777            This is apparently wrong for the Windows case, so I have removed it.
778            (It makes no difference on Unix-like systems.)
780    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
781        of recursive calls to match(). This is different to MATCH_LIMIT because
782        that limits the total number of calls to match(), not all of which increase
783        the depth of recursion. Limiting the recursion depth limits the amount of
784        stack (or heap if NO_RECURSE is set) that is used. The default can be set
785        when PCRE is compiled, and changed at run time. A patch from Google adds
786        this functionality to the C++ interface.
788    18. Changes to the handling of Unicode character properties:
790        (a) Updated the table to Unicode 4.1.0.
792        (b) Recognize characters that are not in the table as "Cn" (undefined).
794        (c) I revised the way the table is implemented to a much improved format
795            which includes recognition of ranges. It now supports the ranges that
796            are defined in UnicodeData.txt, and it also amalgamates other
797            characters into ranges. This has reduced the number of entries in the
798            table from around 16,000 to around 3,000, thus reducing its size
799            considerably. I realized I did not need to use a tree structure after
800            all - a binary chop search is just as efficient. Having reduced the
801            number of entries, I extended their size from 6 bytes to 8 bytes to
802            allow for more data.
804        (d) Added support for Unicode script names via properties such as \p{Han}.
806    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
807        matching that character.
809    20. When matching a repeated Unicode property with a minimum greater than zero,
810        (for example \pL{2,}), PCRE could look past the end of the subject if it
811        reached it while seeking the minimum number of characters. This could
812        happen only if some of the characters were more than one byte long, because
813        there is a check for at least the minimum number of bytes.
815    21. Refactored the implementation of \p and \P so as to be more general, to
816        allow for more different types of property in future. This has changed the
817        compiled form incompatibly. Anybody with saved compiled patterns that use
818        \p or \P will have to recompile them.
820    22. Added "Any" and "L&" to the supported property types.
822    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
823        but give a compile time error if the value is greater than 0xff.
825    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
826        accidentally not being installed or uninstalled.
828    25. The pcre.h file was built from pcre.h.in, but the only changes that were
829        made were to insert the current release number. This seemed silly, because
830        it made things harder for people building PCRE on systems that don't run
831        "configure". I have turned pcre.h into a distributed file, no longer built
832        by "configure", with the version identification directly included. There is
833        no longer a pcre.h.in file.
835        However, this change necessitated a change to the pcre-config script as
836        well. It is built from pcre-config.in, and one of the substitutions was the
837        release number. I have updated configure.ac so that ./configure now finds
838        the release number by grepping pcre.h.
840    26. Added the ability to run the tests under valgrind.
843    Version 6.4 05-Sep-05
844    ---------------------
846     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
847        "--" to be printed when multiple files were scanned, even when none of the
848        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
849        consider it to be a bug, and have restored the previous behaviour.
851     2. A couple of code tidies to get rid of compiler warnings.
853     3. The pcretest program used to cheat by referring to symbols in the library
854        whose names begin with _pcre_. These are internal symbols that are not
855        really supposed to be visible externally, and in some environments it is
856        possible to suppress them. The cheating is now confined to including
857        certain files from the library's source, which is a bit cleaner.
859     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
860        file's purpose clearer.
862     5. Reorganized pcre_ucp_findchar().
865    Version 6.3 15-Aug-05
866    ---------------------
868     1. The file libpcre.pc.in did not have general read permission in the tarball.
870     2. There were some problems when building without C++ support:
872        (a) If C++ support was not built, "make install" and "make test" still
873            tried to test it.
875        (b) There were problems when the value of CXX was explicitly set. Some
876            changes have been made to try to fix these, and ...
878        (c) --disable-cpp can now be used to explicitly disable C++ support.
880        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
881            backslash in a target when C++ was disabled. This confuses some
882            versions of "make", apparently. Using an intermediate variable solves
883            this. (Same for CPP_LOBJ.)
885     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
886        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
887        necessary on certain architectures.
889     4. Added a setting of -export-symbols-regex to the link command to remove
890        those symbols that are exported in the C sense, but actually are local
891        within the library, and not documented. Their names all begin with
892        "_pcre_". This is not a perfect job, because (a) we have to except some
893        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
894        available (and never for static libraries). I have made a note to try to
895        find a way round (a) in the future.
898  Version 6.2 01-Aug-05  Version 6.2 01-Aug-05
899  ---------------------  ---------------------

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