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

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