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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.1 12-Mar-07
5    ---------------------
6    
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other Autotools. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
11    
12     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
13        for recursive directory scanning broke on some systems because the files
14        are not scanned in any specific order and on different systems the order
15        was different. A call to "sort" has been inserted into RunGrepTest for the
16        approprate test as a short-term fix. In the longer term there may be an
17        alternative.
18    
19     3. I had an email from Eric Raymond about problems translating some of PCRE's
20        man pages to HTML (despite the fact that I distribute HTML pages, some
21        people do their own conversions for various reasons). The problems
22        concerned the use of low-level troff macros .br and .in. I have therefore
23        removed all such uses from the man pages (some were redundant, some could
24        be replaced by .nf/.fi pairs). The 132html script that I use to generate
25        HTML has been updated to handle .nf/.fi and to complain if it encounters
26        .br or .in.
27    
28     4. Updated comments in configure.ac that get placed in config.h.in and also
29        arranged for config.h to be included in the distribution, with the name
30        config.h.generic, for the benefit of those who have to compile without
31        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
32    
33     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
34        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
35        makevp.bat for the current PCRE, using the additional files
36        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
37    
38     6. A Windows user reported a minor discrepancy with test 2, which turned out
39        to be caused by a trailing space on an input line that had got lost in his
40        copy. The trailing space was an accident, so I've just removed it.
41    
42     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
43        that is needed.
44    
45     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
46        as "const" (a) because they are and (b) because it helps the PHP
47        maintainers who have recently made a script to detect big data structures
48        in the php code that should be moved to the .rodata section. I remembered
49        to update Builducptable as well, so it won't revert if ucptable.h is ever
50        re-created.
51    
52     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
53        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
54        order to be able to cut out the UTF-8 tables in the latter when UTF-8
55        support is not required. This saves 1.5-2K of code, which is important in
56        some applications.
57    
58        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
59        so as not to refer to the tables, even though these functions will never be
60        called when UTF-8 support is disabled. Otherwise there are problems with a
61        shared library.
62    
63    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
64    
65        (a) It was defining its arguments as char * instead of void *.
66    
67        (b) It was assuming that all moves were upwards in memory; this was true
68            a long time ago when I wrote it, but is no longer the case.
69    
70        The emulated memove() is provided for those environments that have neither
71        memmove() nor bcopy(). I didn't think anyone used it these days, but that
72        is clearly not the case, as these two bugs were recently reported.
73    
74    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
75        and Detrail to create the HTML documentation, the .txt form of the man
76        pages, and it removes trailing spaces from listed files. It also creates
77        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
78        case, it wraps all the #defines with #ifndefs. This script should be run
79        before "make dist".
80    
81    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
82        with Unicode property support.
83    
84        (a) For a maximizing quantifier, if the two different cases of the
85            character were of different lengths in their UTF-8 codings (there are
86            some cases like this - I found 11), and the matching function had to
87            back up over a mixture of the two cases, it incorrectly assumed they
88            were both the same length.
89    
90        (b) When PCRE was configured to use the heap rather than the stack for
91            recursion during matching, it was not correctly preserving the data for
92            the other case of a UTF-8 character when checking ahead for a match
93            while processing a minimizing repeat. If the check also involved
94            matching a wide character, but failed, corruption could cause an
95            erroneous result when trying to check for a repeat of the original
96            character.
97    
98    13. Some tidying changes to the testing mechanism:
99    
100        (a) The RunTest script now detects the internal link size and whether there
101            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
102            values substituted by "configure". (The RunGrepTest script already did
103            this for UTF-8.) The configure.ac script no longer substitutes the
104            relevant variables.
105    
106        (b) The debugging options /B and /D in pcretest show the compiled bytecode
107            with length and offset values. This means that the output is different
108            for different internal link sizes. Test 2 is skipped for link sizes
109            other than 2 because of this, bypassing the problem. Unfortunately,
110            there was also a test in test 3 (the locale tests) that used /B and
111            failed for link sizes other than 2. Rather than cut the whole test out,
112            I have added a new /Z option to pcretest that replaces the length and
113            offset values with spaces. This is now used to make test 3 independent
114            of link size. (Test 2 will be tidied up later.)
115    
116    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
117        segmentation fault instead of returning the appropriate error message.
118    
119    15. In multiline mode when the newline sequence was set to "any", the pattern
120        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
121        This doesn't seem right; it now treats the CRLF combination as the line
122        ending, and so does not match in that case. It's only a pattern such as ^$
123        that would hit this one: something like ^ABC$ would have failed after \r
124        and then tried again after \r\n.
125    
126    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
127        in an attempt to make files that differ only in their line terminators
128        compare equal. This works on Linux.
129    
130    17. Under certain error circumstances pcregrep might try to free random memory
131        as it exited. This is now fixed, thanks to valgrind.
132    
133    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
134        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
135        was because its rules for how to advance for /g after matching an empty
136        string did not allow for this case. They now check for it specially.
137    
138    
139    Version 7.0 19-Dec-06
140    ---------------------
141    
142     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
143        moving to gcc 4.1.1.
144    
145     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
146        sys/time.h, which is documented as needed for this function. It doesn't
147        seem to matter on Linux, but it showed up on some releases of OS X.
148    
149     3. It seems that there are systems where bytes whose values are greater than
150        127 match isprint() in the "C" locale. The "C" locale should be the
151        default when a C program starts up. In most systems, only ASCII printing
152        characters match isprint(). This difference caused the output from pcretest
153        to vary, making some of the tests fail. I have changed pcretest so that:
154    
155        (a) When it is outputting text in the compiled version of a pattern, bytes
156            other than 32-126 are always shown as hex escapes.
157    
158        (b) When it is outputting text that is a matched part of a subject string,
159            it does the same, unless a different locale has been set for the match
160            (using the /L modifier). In this case, it uses isprint() to decide.
161    
162     4. Fixed a major bug that caused incorrect computation of the amount of memory
163        required for a compiled pattern when options that changed within the
164        pattern affected the logic of the preliminary scan that determines the
165        length. The relevant options are -x, and -i in UTF-8 mode. The result was
166        that the computed length was too small. The symptoms of this bug were
167        either the PCRE error "internal error: code overflow" from pcre_compile(),
168        or a glibc crash with a message such as "pcretest: free(): invalid next
169        size (fast)". Examples of patterns that provoked this bug (shown in
170        pcretest format) are:
171    
172          /(?-x: )/x
173          /(?x)(?-x: \s*#\s*)/
174          /((?i)[\x{c0}])/8
175          /(?i:[\x{c0}])/8
176    
177        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
178        is now done differently.
179    
180     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
181        wrapper classes; (b) implement a new function in the C++ scanner that is
182        more efficient than the old way of doing things because it avoids levels of
183        recursion in the regex matching; (c) add a paragraph to the documentation
184        for the FullMatch() function.
185    
186     6. The escape sequence \n was being treated as whatever was defined as
187        "newline". Not only was this contrary to the documentation, which states
188        that \n is character 10 (hex 0A), but it also went horribly wrong when
189        "newline" was defined as CRLF. This has been fixed.
190    
191     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
192        was being set to -1 for the "end of line" case (supposedly a value that no
193        character can have). Though this value is never used (the check for end of
194        line is "zero bytes in current character"), it caused compiler complaints.
195        I've changed it to 0xffffffff.
196    
197     8. In pcre_version.c, the version string was being built by a sequence of
198        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
199        string (as it is for production releases) called a macro with an empty
200        argument. The C standard says the result of this is undefined. The gcc
201        compiler treats it as an empty string (which was what was wanted) but it is
202        reported that Visual C gives an error. The source has been hacked around to
203        avoid this problem.
204    
205     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
206        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
207        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
208        of them did).
209    
210    10. Originally, pcretest opened its input and output without "b"; then I was
211        told that "b" was needed in some environments, so it was added for release
212        5.0 to both the input and output. (It makes no difference on Unix-like
213        systems.) Later I was told that it is wrong for the input on Windows. I've
214        now abstracted the modes into two macros, to make it easier to fiddle with
215        them, and removed "b" from the input mode under Windows.
216    
217    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
218    
219    12. Added -help and --help to pcretest as an official way of being reminded
220        of the options.
221    
222    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
223        and pcrecpp.cc because they annoy compilers at high warning levels.
224    
225    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
226    
227    15. Fixed an occurrence of == in configure.ac that should have been = (shell
228        scripts are not C programs :-) and which was not noticed because it works
229        on Linux.
230    
231    16. pcretest is supposed to handle any length of pattern and data line (as one
232        line or as a continued sequence of lines) by extending its input buffer if
233        necessary. This feature was broken for very long pattern lines, leading to
234        a string of junk being passed to pcre_compile() if the pattern was longer
235        than about 50K.
236    
237    17. I have done a major re-factoring of the way pcre_compile() computes the
238        amount of memory needed for a compiled pattern. Previously, there was code
239        that made a preliminary scan of the pattern in order to do this. That was
240        OK when PCRE was new, but as the facilities have expanded, it has become
241        harder and harder to keep it in step with the real compile phase, and there
242        have been a number of bugs (see for example, 4 above). I have now found a
243        cunning way of running the real compile function in a "fake" mode that
244        enables it to compute how much memory it would need, while actually only
245        ever using a few hundred bytes of working memory and without too many
246        tests of the mode. This should make future maintenance and development
247        easier. A side effect of this work is that the limit of 200 on the nesting
248        depth of parentheses has been removed (though this was never a serious
249        limitation, I suspect). However, there is a downside: pcre_compile() now
250        runs more slowly than before (30% or more, depending on the pattern). I
251        hope this isn't a big issue. There is no effect on runtime performance.
252    
253    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
254        newline (only possible for the last line of a file) and it was a
255        pattern that set a locale (followed by /Lsomething), pcretest crashed.
256    
257    19. Added additional timing features to pcretest. (1) The -tm option now times
258        matching only, not compiling. (2) Both -t and -tm can be followed, as a
259        separate command line item, by a number that specifies the number of
260        repeats to use when timing. The default is 50000; this gives better
261        precision, but takes uncomfortably long for very large patterns.
262    
263    20. Extended pcre_study() to be more clever in cases where a branch of a
264        subpattern has no definite first character. For example, (a*|b*)[cd] would
265        previously give no result from pcre_study(). Now it recognizes that the
266        first character must be a, b, c, or d.
267    
268    21. There was an incorrect error "recursive call could loop indefinitely" if
269        a subpattern (or the entire pattern) that was being tested for matching an
270        empty string contained only one non-empty item after a nested subpattern.
271        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
272        incorrectly, because the \d was being skipped in the check.
273    
274    22. The pcretest program now has a new pattern option /B and a command line
275        option -b, which is equivalent to adding /B to every pattern. This causes
276        it to show the compiled bytecode, without the additional information that
277        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
278        is the same as /B/I).
279    
280    23. A new optimization is now able automatically to treat some sequences such
281        as a*b as a*+b. More specifically, if something simple (such as a character
282        or a simple class like \d) has an unlimited quantifier, and is followed by
283        something that cannot possibly match the quantified thing, the quantifier
284        is automatically "possessified".
285    
286    24. A recursive reference to a subpattern whose number was greater than 39
287        went wrong under certain circumstances in UTF-8 mode. This bug could also
288        have affected the operation of pcre_study().
289    
290    25. Realized that a little bit of performance could be had by replacing
291        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
292    
293    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
294    
295    27. Possessive quantifiers such as a++ were previously implemented by turning
296        them into atomic groups such as ($>a+). Now they have their own opcodes,
297        which improves performance. This includes the automatically created ones
298        from 23 above.
299    
300    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
301        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
302        the first matched character to be a colon. This applied both to named and
303        numbered groups.
304    
305    29. The ucpinternal.h header file was missing its idempotency #ifdef.
306    
307    30. I was sent a "project" file called libpcre.a.dev which I understand makes
308        building PCRE on Windows easier, so I have included it in the distribution.
309    
310    31. There is now a check in pcretest against a ridiculously large number being
311        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
312        loop, the loop is abandoned.
313    
314    32. Forward references to subpatterns in conditions such as (?(2)...) where
315        subpattern 2 is defined later cause pcre_compile() to search forwards in
316        the pattern for the relevant set of parentheses. This search went wrong
317        when there were unescaped parentheses in a character class, parentheses
318        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
319    
320    33. "Subroutine" calls and backreferences were previously restricted to
321        referencing subpatterns earlier in the regex. This restriction has now
322        been removed.
323    
324    34. Added a number of extra features that are going to be in Perl 5.10. On the
325        whole, these are just syntactic alternatives for features that PCRE had
326        previously implemented using the Python syntax or my own invention. The
327        other formats are all retained for compatibility.
328    
329        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
330            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
331            also .NET compatible.
332    
333        (b) A recursion or subroutine call to a named group can now be defined as
334            (?&name) as well as (?P>name).
335    
336        (c) A backreference to a named group can now be defined as \k<name> or
337            \k'name' as well as (?P=name). The new forms, as well as being in Perl
338            5.10, are also .NET compatible.
339    
340        (d) A conditional reference to a named group can now use the syntax
341            (?(<name>) or (?('name') as well as (?(name).
342    
343        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
344            groups (named and numbered) that are never evaluated inline, but can be
345            called as "subroutines" from elsewhere. In effect, the DEFINE condition
346            is always false. There may be only one alternative in such a group.
347    
348        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
349            as the simple (?(R). The condition is true only if the most recent
350            recursion is that of the given number or name. It does not search out
351            through the entire recursion stack.
352    
353        (g) The escape \gN or \g{N} has been added, where N is a positive or
354            negative number, specifying an absolute or relative reference.
355    
356    35. Tidied to get rid of some further signed/unsigned compiler warnings and
357        some "unreachable code" warnings.
358    
359    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
360        things, this adds five new scripts.
361    
362    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
363        There were also incompatibilities regarding the handling of \Q..\E inside
364        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
365        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
366    
367    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
368        matches an empty string, and forcibly breaks the loop. There were bugs in
369        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
370        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
371        separate and independent bugs (that affected different cases) have been
372        fixed.
373    
374    39. Refactored the code to abolish the use of different opcodes for small
375        capturing bracket numbers. This is a tidy that I avoided doing when I
376        removed the limit on the number of capturing brackets for 3.5 back in 2001.
377        The new approach is not only tidier, it makes it possible to reduce the
378        memory needed to fix the previous bug (38).
379    
380    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
381        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
382        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
383        mode.
384    
385    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
386        report.
387    
388    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
389        copy construction and assignment in the C++ wrapper.
390    
391    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
392        couple of bugs that could have given wrong results in the "--newline=crlf"
393        case.
394    
395    44. Added a number of casts and did some reorganization of signed/unsigned int
396        variables following suggestions from Dair Grant. Also renamed the variable
397        "this" as "item" because it is a C++ keyword.
398    
399    45. Arranged for dftables to add
400    
401          #include "pcre_internal.h"
402    
403        to pcre_chartables.c because without it, gcc 4.x may remove the array
404        definition from the final binary if PCRE is built into a static library and
405        dead code stripping is activated.
406    
407    46. For an unanchored pattern, if a match attempt fails at the start of a
408        newline sequence, and the newline setting is CRLF or ANY, and the next two
409        characters are CRLF, advance by two characters instead of one.
410    
411    
412    Version 6.7 04-Jul-06
413    ---------------------
414    
415     1. In order to handle tests when input lines are enormously long, pcretest has
416        been re-factored so that it automatically extends its buffers when
417        necessary. The code is crude, but this _is_ just a test program. The
418        default size has been increased from 32K to 50K.
419    
420     2. The code in pcre_study() was using the value of the re argument before
421        testing it for NULL. (Of course, in any sensible call of the function, it
422        won't be NULL.)
423    
424     3. The memmove() emulation function in pcre_internal.h, which is used on
425        systems that lack both memmove() and bcopy() - that is, hardly ever -
426        was missing a "static" storage class specifier.
427    
428     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
429        containing an extended class (one that cannot be represented by a bitmap
430        because it contains high-valued characters or Unicode property items, e.g.
431        [\pZ]). Almost always one would set UTF-8 mode when processing such a
432        pattern, but PCRE should not loop if you do not (it no longer does).
433        [Detail: two cases were found: (a) a repeated subpattern containing an
434        extended class; (b) a recursive reference to a subpattern that followed a
435        previous extended class. It wasn't skipping over the extended class
436        correctly when UTF-8 mode was not set.]
437    
438     5. A negated single-character class was not being recognized as fixed-length
439        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
440        compile error "lookbehind assertion is not fixed length".
441    
442     6. The RunPerlTest auxiliary script was showing an unexpected difference
443        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
444        write a Perl script that can interpret lines of an input file either as
445        byte characters or as UTF-8, which is what "perltest" was being required to
446        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
447        can't do is switch easily at run time between having the "use utf8;" pragma
448        or not. In the end, I fudged it by using the RunPerlTest script to insert
449        "use utf8;" explicitly for the UTF-8 tests.
450    
451     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
452        the end of the subject string, contrary to the documentation and to what
453        Perl does. This was true of both matching functions. Now it matches only at
454        the start of the subject and immediately after *internal* newlines.
455    
456     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
457        a pointer to an int instead of a pointer to an unsigned long int. This
458        caused problems on 64-bit systems.
459    
460     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
461        instance of the 'standard' template library not being so standard".
462    
463    10. There was no check on the number of named subpatterns nor the maximum
464        length of a subpattern name. The product of these values is used to compute
465        the size of the memory block for a compiled pattern. By supplying a very
466        long subpattern name and a large number of named subpatterns, the size
467        computation could be caused to overflow. This is now prevented by limiting
468        the length of names to 32 characters, and the number of named subpatterns
469        to 10,000.
470    
471    11. Subpatterns that are repeated with specific counts have to be replicated in
472        the compiled pattern. The size of memory for this was computed from the
473        length of the subpattern and the repeat count. The latter is limited to
474        65535, but there was no limit on the former, meaning that integer overflow
475        could in principle occur. The compiled length of a repeated subpattern is
476        now limited to 30,000 bytes in order to prevent this.
477    
478    12. Added the optional facility to have named substrings with the same name.
479    
480    13. Added the ability to use a named substring as a condition, using the
481        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
482        are numbers (not recommended). Forward references are permitted.
483    
484    14. Added forward references in named backreferences (if you see what I mean).
485    
486    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
487        pattern could run off the end of the subject. For example, the pattern
488        "(?s)(.{1,5})"8 did this with the subject "ab".
489    
490    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
491        PCRE_CASELESS was set when matching characters that were quantified with ?
492        or *.
493    
494    17. A character class other than a single negated character that had a minimum
495        but no maximum quantifier - for example [ab]{6,} - was not handled
496        correctly by pce_dfa_exec(). It would match only one character.
497    
498    18. A valid (though odd) pattern that looked like a POSIX character
499        class but used an invalid character after [ (for example [[,abc,]]) caused
500        pcre_compile() to give the error "Failed: internal error: code overflow" or
501        in some cases to crash with a glibc free() error. This could even happen if
502        the pattern terminated after [[ but there just happened to be a sequence of
503        letters, a binary zero, and a closing ] in the memory that followed.
504    
505    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
506        over the years. Originally (before any Unicode support), just the bottom 8
507        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
508        output from "man perlunicode" includes this:
509    
510          The regular expression compiler produces polymorphic opcodes.  That
511          is, the pattern adapts to the data and automatically switches to
512          the Unicode character scheme when presented with Unicode data--or
513          instead uses a traditional byte scheme when presented with byte
514          data.
515    
516        Sadly, a wide octal escape does not cause a switch, and in a string with
517        no other multibyte characters, these octal escapes are treated as before.
518        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
519        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
520        Unicode string.
521    
522        I have not perpetrated such confusion in PCRE. Up till now, it took just
523        the bottom 8 bits, as in old Perl. I have now made octal escapes with
524        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
525        translate to the appropriate multibyte character.
526    
527    29. Applied some refactoring to reduce the number of warnings from Microsoft
528        and Borland compilers. This has included removing the fudge introduced
529        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
530        a warning about an unused variable.
531    
532    21. PCRE has not included VT (character 0x0b) in the set of whitespace
533        characters since release 4.0, because Perl (from release 5.004) does not.
534        [Or at least, is documented not to: some releases seem to be in conflict
535        with the documentation.] However, when a pattern was studied with
536        pcre_study() and all its branches started with \s, PCRE still included VT
537        as a possible starting character. Of course, this did no harm; it just
538        caused an unnecessary match attempt.
539    
540    22. Removed a now-redundant internal flag bit that recorded the fact that case
541        dependency changed within the pattern. This was once needed for "required
542        byte" processing, but is no longer used. This recovers a now-scarce options
543        bit. Also moved the least significant internal flag bit to the most-
544        significant bit of the word, which was not previously used (hangover from
545        the days when it was an int rather than a uint) to free up another bit for
546        the future.
547    
548    23. Added support for CRLF line endings as well as CR and LF. As well as the
549        default being selectable at build time, it can now be changed at runtime
550        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
551        specify that it is scanning data with non-default line endings.
552    
553    24. Changed the definition of CXXLINK to make it agree with the definition of
554        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
555    
556    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
557        recursions. This makes a big different to stack usage for some patterns.
558    
559    26. If a subpattern containing a named recursion or subroutine reference such
560        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
561        the space required for the compiled pattern went wrong and gave too small a
562        value. Depending on the environment, this could lead to "Failed: internal
563        error: code overflow at offset 49" or "glibc detected double free or
564        corruption" errors.
565    
566    27. Applied patches from Google (a) to support the new newline modes and (b) to
567        advance over multibyte UTF-8 characters in GlobalReplace.
568    
569    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
570        difference for some implementation of PCRE in some Windows version.
571    
572    29. Added some extra testing facilities to pcretest:
573    
574        \q<number>   in a data line sets the "match limit" value
575        \Q<number>   in a data line sets the "match recursion limt" value
576        -S <number>  sets the stack size, where <number> is in megabytes
577    
578        The -S option isn't available for Windows.
579    
580    
581    Version 6.6 06-Feb-06
582    ---------------------
583    
584     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
585        in pcreposix.h. I have copied the definition from pcre.h.
586    
587     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
588        because pcre.h is no longer a built file.
589    
590     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
591        not normally included in the compiled code.
592    
593    
594    Version 6.5 01-Feb-06
595    ---------------------
596    
597     1. When using the partial match feature with pcre_dfa_exec(), it was not
598        anchoring the second and subsequent partial matches at the new starting
599        point. This could lead to incorrect results. For example, with the pattern
600        /1234/, partially matching against "123" and then "a4" gave a match.
601    
602     2. Changes to pcregrep:
603    
604        (a) All non-match returns from pcre_exec() were being treated as failures
605            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
606            error message is output. Some extra information is given for the
607            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
608            probably the only errors that are likely to be caused by users (by
609            specifying a regex that has nested indefinite repeats, for instance).
610            If there are more than 20 of these errors, pcregrep is abandoned.
611    
612        (b) A binary zero was treated as data while matching, but terminated the
613            output line if it was written out. This has been fixed: binary zeroes
614            are now no different to any other data bytes.
615    
616        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
617            used to set a locale for matching. The --locale=xxxx long option has
618            been added (no short equivalent) to specify a locale explicitly on the
619            pcregrep command, overriding the environment variables.
620    
621        (d) When -B was used with -n, some line numbers in the output were one less
622            than they should have been.
623    
624        (e) Added the -o (--only-matching) option.
625    
626        (f) If -A or -C was used with -c (count only), some lines of context were
627            accidentally printed for the final match.
628    
629        (g) Added the -H (--with-filename) option.
630    
631        (h) The combination of options -rh failed to suppress file names for files
632            that were found from directory arguments.
633    
634        (i) Added the -D (--devices) and -d (--directories) options.
635    
636        (j) Added the -F (--fixed-strings) option.
637    
638        (k) Allow "-" to be used as a file name for -f as well as for a data file.
639    
640        (l) Added the --colo(u)r option.
641    
642        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
643            is not present by default.
644    
645     3. A nasty bug was discovered in the handling of recursive patterns, that is,
646        items such as (?R) or (?1), when the recursion could match a number of
647        alternatives. If it matched one of the alternatives, but subsequently,
648        outside the recursion, there was a failure, the code tried to back up into
649        the recursion. However, because of the way PCRE is implemented, this is not
650        possible, and the result was an incorrect result from the match.
651    
652        In order to prevent this happening, the specification of recursion has
653        been changed so that all such subpatterns are automatically treated as
654        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
655    
656     4. I had overlooked the fact that, in some locales, there are characters for
657        which isalpha() is true but neither isupper() nor islower() are true. In
658        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
659        and ordfeminine) are like this. This affected the treatment of \w and \W
660        when they appeared in character classes, but not when they appeared outside
661        a character class. The bit map for "word" characters is now created
662        separately from the results of isalnum() instead of just taking it from the
663        upper, lower, and digit maps. (Plus the underscore character, of course.)
664    
665     5. The above bug also affected the handling of POSIX character classes such as
666        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
667        permanent tables. Instead, the bit maps for such a class were previously
668        created as the appropriate unions of the upper, lower, and digit bitmaps.
669        Now they are created by subtraction from the [[:word:]] class, which has
670        its own bitmap.
671    
672     6. The [[:blank:]] character class matches horizontal, but not vertical space.
673        It is created by subtracting the vertical space characters (\x09, \x0a,
674        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
675        subtraction was done in the overall bitmap for a character class, meaning
676        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
677        be recognized. This bug has been fixed.
678    
679     7. Patches from the folks at Google:
680    
681          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
682          real life, but is still worth protecting against".
683    
684          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
685          regular expressions".
686    
687          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
688          have it.
689    
690          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
691          "configure" and the latter not, in order to fix a problem somebody had
692          with compiling the Arg class on HP-UX.
693    
694          (e) Improve the error-handling of the C++ wrapper a little bit.
695    
696          (f) New tests for checking recursion limiting.
697    
698     8. The pcre_memmove() function, which is used only if the environment does not
699        have a standard memmove() function (and is therefore rarely compiled),
700        contained two bugs: (a) use of int instead of size_t, and (b) it was not
701        returning a result (though PCRE never actually uses the result).
702    
703     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
704        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
705        returned instead of calling malloc() with an overflowing number that would
706        most likely cause subsequent chaos.
707    
708    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
709    
710    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
711        with this option is matched, the nmatch and pmatch options of regexec() are
712        ignored.
713    
714    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
715        provided in case anyone wants to the the POSIX interface with UTF-8
716        strings.
717    
718    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
719        C++ linking (needed for some HP-UX environments).
720    
721    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
722        (unused parameter) and in the pcre_printint() function (omitted "default"
723        switch label when the default is to do nothing).
724    
725    15. Added some code to make it possible, when PCRE is compiled as a C++
726        library, to replace subject pointers for pcre_exec() with a smart pointer
727        class, thus making it possible to process discontinuous strings.
728    
729    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
730        much the same function. They were added by different people who were trying
731        to make PCRE easy to compile on non-Unix systems. It has been suggested
732        that PCRE_EXPORT be abolished now that there is more automatic apparatus
733        for compiling on Windows systems. I have therefore replaced it with
734        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
735        defaults to "extern" for C or "extern C" for C++, which works fine on
736        Unix-like systems. It is now possible to override the value of PCRE_DATA_
737        SCOPE with something explicit in config.h. In addition:
738    
739        (a) pcreposix.h still had just "extern" instead of either of these macros;
740            I have replaced it with PCRE_DATA_SCOPE.
741    
742        (b) Functions such as _pcre_xclass(), which are internal to the library,
743            but external in the C sense, all had PCRE_EXPORT in their definitions.
744            This is apparently wrong for the Windows case, so I have removed it.
745            (It makes no difference on Unix-like systems.)
746    
747    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
748        of recursive calls to match(). This is different to MATCH_LIMIT because
749        that limits the total number of calls to match(), not all of which increase
750        the depth of recursion. Limiting the recursion depth limits the amount of
751        stack (or heap if NO_RECURSE is set) that is used. The default can be set
752        when PCRE is compiled, and changed at run time. A patch from Google adds
753        this functionality to the C++ interface.
754    
755    18. Changes to the handling of Unicode character properties:
756    
757        (a) Updated the table to Unicode 4.1.0.
758    
759        (b) Recognize characters that are not in the table as "Cn" (undefined).
760    
761        (c) I revised the way the table is implemented to a much improved format
762            which includes recognition of ranges. It now supports the ranges that
763            are defined in UnicodeData.txt, and it also amalgamates other
764            characters into ranges. This has reduced the number of entries in the
765            table from around 16,000 to around 3,000, thus reducing its size
766            considerably. I realized I did not need to use a tree structure after
767            all - a binary chop search is just as efficient. Having reduced the
768            number of entries, I extended their size from 6 bytes to 8 bytes to
769            allow for more data.
770    
771        (d) Added support for Unicode script names via properties such as \p{Han}.
772    
773    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
774        matching that character.
775    
776    20. When matching a repeated Unicode property with a minimum greater than zero,
777        (for example \pL{2,}), PCRE could look past the end of the subject if it
778        reached it while seeking the minimum number of characters. This could
779        happen only if some of the characters were more than one byte long, because
780        there is a check for at least the minimum number of bytes.
781    
782    21. Refactored the implementation of \p and \P so as to be more general, to
783        allow for more different types of property in future. This has changed the
784        compiled form incompatibly. Anybody with saved compiled patterns that use
785        \p or \P will have to recompile them.
786    
787    22. Added "Any" and "L&" to the supported property types.
788    
789    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
790        but give a compile time error if the value is greater than 0xff.
791    
792    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
793        accidentally not being installed or uninstalled.
794    
795    25. The pcre.h file was built from pcre.h.in, but the only changes that were
796        made were to insert the current release number. This seemed silly, because
797        it made things harder for people building PCRE on systems that don't run
798        "configure". I have turned pcre.h into a distributed file, no longer built
799        by "configure", with the version identification directly included. There is
800        no longer a pcre.h.in file.
801    
802        However, this change necessitated a change to the pcre-config script as
803        well. It is built from pcre-config.in, and one of the substitutions was the
804        release number. I have updated configure.ac so that ./configure now finds
805        the release number by grepping pcre.h.
806    
807    26. Added the ability to run the tests under valgrind.
808    
809    
810    Version 6.4 05-Sep-05
811    ---------------------
812    
813     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
814        "--" to be printed when multiple files were scanned, even when none of the
815        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
816        consider it to be a bug, and have restored the previous behaviour.
817    
818     2. A couple of code tidies to get rid of compiler warnings.
819    
820     3. The pcretest program used to cheat by referring to symbols in the library
821        whose names begin with _pcre_. These are internal symbols that are not
822        really supposed to be visible externally, and in some environments it is
823        possible to suppress them. The cheating is now confined to including
824        certain files from the library's source, which is a bit cleaner.
825    
826     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
827        file's purpose clearer.
828    
829     5. Reorganized pcre_ucp_findchar().
830    
831    
832  Version 6.3 15-Aug-05  Version 6.3 15-Aug-05
833  ---------------------  ---------------------
834    

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