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revision 81 by nigel, Sat Feb 24 21:40:59 2007 UTC revision 151 by ph10, Tue Apr 17 15:07:29 2007 UTC
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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 at the end of a line did not allow for this case. They now check for
137        it specially.
138    
139    20. pcretest is supposed to handle patterns and data of any length, by
140        extending its buffers when necessary. It was getting this wrong when the
141        buffer for a data line had to be extended.
142    
143    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
144        CRLF as a newline sequence.
145    
146    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
147        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
148        I have nevertheless tidied it up.
149    
150    23. Added some casts to kill warnings from HP-UX ia64 compiler.
151    
152    
153    Version 7.0 19-Dec-06
154    ---------------------
155    
156     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
157        moving to gcc 4.1.1.
158    
159     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
160        sys/time.h, which is documented as needed for this function. It doesn't
161        seem to matter on Linux, but it showed up on some releases of OS X.
162    
163     3. It seems that there are systems where bytes whose values are greater than
164        127 match isprint() in the "C" locale. The "C" locale should be the
165        default when a C program starts up. In most systems, only ASCII printing
166        characters match isprint(). This difference caused the output from pcretest
167        to vary, making some of the tests fail. I have changed pcretest so that:
168    
169        (a) When it is outputting text in the compiled version of a pattern, bytes
170            other than 32-126 are always shown as hex escapes.
171    
172        (b) When it is outputting text that is a matched part of a subject string,
173            it does the same, unless a different locale has been set for the match
174            (using the /L modifier). In this case, it uses isprint() to decide.
175    
176     4. Fixed a major bug that caused incorrect computation of the amount of memory
177        required for a compiled pattern when options that changed within the
178        pattern affected the logic of the preliminary scan that determines the
179        length. The relevant options are -x, and -i in UTF-8 mode. The result was
180        that the computed length was too small. The symptoms of this bug were
181        either the PCRE error "internal error: code overflow" from pcre_compile(),
182        or a glibc crash with a message such as "pcretest: free(): invalid next
183        size (fast)". Examples of patterns that provoked this bug (shown in
184        pcretest format) are:
185    
186          /(?-x: )/x
187          /(?x)(?-x: \s*#\s*)/
188          /((?i)[\x{c0}])/8
189          /(?i:[\x{c0}])/8
190    
191        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
192        is now done differently.
193    
194     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
195        wrapper classes; (b) implement a new function in the C++ scanner that is
196        more efficient than the old way of doing things because it avoids levels of
197        recursion in the regex matching; (c) add a paragraph to the documentation
198        for the FullMatch() function.
199    
200     6. The escape sequence \n was being treated as whatever was defined as
201        "newline". Not only was this contrary to the documentation, which states
202        that \n is character 10 (hex 0A), but it also went horribly wrong when
203        "newline" was defined as CRLF. This has been fixed.
204    
205     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
206        was being set to -1 for the "end of line" case (supposedly a value that no
207        character can have). Though this value is never used (the check for end of
208        line is "zero bytes in current character"), it caused compiler complaints.
209        I've changed it to 0xffffffff.
210    
211     8. In pcre_version.c, the version string was being built by a sequence of
212        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
213        string (as it is for production releases) called a macro with an empty
214        argument. The C standard says the result of this is undefined. The gcc
215        compiler treats it as an empty string (which was what was wanted) but it is
216        reported that Visual C gives an error. The source has been hacked around to
217        avoid this problem.
218    
219     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
220        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
221        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
222        of them did).
223    
224    10. Originally, pcretest opened its input and output without "b"; then I was
225        told that "b" was needed in some environments, so it was added for release
226        5.0 to both the input and output. (It makes no difference on Unix-like
227        systems.) Later I was told that it is wrong for the input on Windows. I've
228        now abstracted the modes into two macros, to make it easier to fiddle with
229        them, and removed "b" from the input mode under Windows.
230    
231    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
232    
233    12. Added -help and --help to pcretest as an official way of being reminded
234        of the options.
235    
236    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
237        and pcrecpp.cc because they annoy compilers at high warning levels.
238    
239    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
240    
241    15. Fixed an occurrence of == in configure.ac that should have been = (shell
242        scripts are not C programs :-) and which was not noticed because it works
243        on Linux.
244    
245    16. pcretest is supposed to handle any length of pattern and data line (as one
246        line or as a continued sequence of lines) by extending its input buffer if
247        necessary. This feature was broken for very long pattern lines, leading to
248        a string of junk being passed to pcre_compile() if the pattern was longer
249        than about 50K.
250    
251    17. I have done a major re-factoring of the way pcre_compile() computes the
252        amount of memory needed for a compiled pattern. Previously, there was code
253        that made a preliminary scan of the pattern in order to do this. That was
254        OK when PCRE was new, but as the facilities have expanded, it has become
255        harder and harder to keep it in step with the real compile phase, and there
256        have been a number of bugs (see for example, 4 above). I have now found a
257        cunning way of running the real compile function in a "fake" mode that
258        enables it to compute how much memory it would need, while actually only
259        ever using a few hundred bytes of working memory and without too many
260        tests of the mode. This should make future maintenance and development
261        easier. A side effect of this work is that the limit of 200 on the nesting
262        depth of parentheses has been removed (though this was never a serious
263        limitation, I suspect). However, there is a downside: pcre_compile() now
264        runs more slowly than before (30% or more, depending on the pattern). I
265        hope this isn't a big issue. There is no effect on runtime performance.
266    
267    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
268        newline (only possible for the last line of a file) and it was a
269        pattern that set a locale (followed by /Lsomething), pcretest crashed.
270    
271    19. Added additional timing features to pcretest. (1) The -tm option now times
272        matching only, not compiling. (2) Both -t and -tm can be followed, as a
273        separate command line item, by a number that specifies the number of
274        repeats to use when timing. The default is 50000; this gives better
275        precision, but takes uncomfortably long for very large patterns.
276    
277    20. Extended pcre_study() to be more clever in cases where a branch of a
278        subpattern has no definite first character. For example, (a*|b*)[cd] would
279        previously give no result from pcre_study(). Now it recognizes that the
280        first character must be a, b, c, or d.
281    
282    21. There was an incorrect error "recursive call could loop indefinitely" if
283        a subpattern (or the entire pattern) that was being tested for matching an
284        empty string contained only one non-empty item after a nested subpattern.
285        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
286        incorrectly, because the \d was being skipped in the check.
287    
288    22. The pcretest program now has a new pattern option /B and a command line
289        option -b, which is equivalent to adding /B to every pattern. This causes
290        it to show the compiled bytecode, without the additional information that
291        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
292        is the same as /B/I).
293    
294    23. A new optimization is now able automatically to treat some sequences such
295        as a*b as a*+b. More specifically, if something simple (such as a character
296        or a simple class like \d) has an unlimited quantifier, and is followed by
297        something that cannot possibly match the quantified thing, the quantifier
298        is automatically "possessified".
299    
300    24. A recursive reference to a subpattern whose number was greater than 39
301        went wrong under certain circumstances in UTF-8 mode. This bug could also
302        have affected the operation of pcre_study().
303    
304    25. Realized that a little bit of performance could be had by replacing
305        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
306    
307    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
308    
309    27. Possessive quantifiers such as a++ were previously implemented by turning
310        them into atomic groups such as ($>a+). Now they have their own opcodes,
311        which improves performance. This includes the automatically created ones
312        from 23 above.
313    
314    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
315        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
316        the first matched character to be a colon. This applied both to named and
317        numbered groups.
318    
319    29. The ucpinternal.h header file was missing its idempotency #ifdef.
320    
321    30. I was sent a "project" file called libpcre.a.dev which I understand makes
322        building PCRE on Windows easier, so I have included it in the distribution.
323    
324    31. There is now a check in pcretest against a ridiculously large number being
325        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
326        loop, the loop is abandoned.
327    
328    32. Forward references to subpatterns in conditions such as (?(2)...) where
329        subpattern 2 is defined later cause pcre_compile() to search forwards in
330        the pattern for the relevant set of parentheses. This search went wrong
331        when there were unescaped parentheses in a character class, parentheses
332        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
333    
334    33. "Subroutine" calls and backreferences were previously restricted to
335        referencing subpatterns earlier in the regex. This restriction has now
336        been removed.
337    
338    34. Added a number of extra features that are going to be in Perl 5.10. On the
339        whole, these are just syntactic alternatives for features that PCRE had
340        previously implemented using the Python syntax or my own invention. The
341        other formats are all retained for compatibility.
342    
343        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
344            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
345            also .NET compatible.
346    
347        (b) A recursion or subroutine call to a named group can now be defined as
348            (?&name) as well as (?P>name).
349    
350        (c) A backreference to a named group can now be defined as \k<name> or
351            \k'name' as well as (?P=name). The new forms, as well as being in Perl
352            5.10, are also .NET compatible.
353    
354        (d) A conditional reference to a named group can now use the syntax
355            (?(<name>) or (?('name') as well as (?(name).
356    
357        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
358            groups (named and numbered) that are never evaluated inline, but can be
359            called as "subroutines" from elsewhere. In effect, the DEFINE condition
360            is always false. There may be only one alternative in such a group.
361    
362        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
363            as the simple (?(R). The condition is true only if the most recent
364            recursion is that of the given number or name. It does not search out
365            through the entire recursion stack.
366    
367        (g) The escape \gN or \g{N} has been added, where N is a positive or
368            negative number, specifying an absolute or relative reference.
369    
370    35. Tidied to get rid of some further signed/unsigned compiler warnings and
371        some "unreachable code" warnings.
372    
373    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
374        things, this adds five new scripts.
375    
376    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
377        There were also incompatibilities regarding the handling of \Q..\E inside
378        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
379        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
380    
381    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
382        matches an empty string, and forcibly breaks the loop. There were bugs in
383        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
384        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
385        separate and independent bugs (that affected different cases) have been
386        fixed.
387    
388    39. Refactored the code to abolish the use of different opcodes for small
389        capturing bracket numbers. This is a tidy that I avoided doing when I
390        removed the limit on the number of capturing brackets for 3.5 back in 2001.
391        The new approach is not only tidier, it makes it possible to reduce the
392        memory needed to fix the previous bug (38).
393    
394    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
395        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
396        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
397        mode.
398    
399    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
400        report.
401    
402    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
403        copy construction and assignment in the C++ wrapper.
404    
405    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
406        couple of bugs that could have given wrong results in the "--newline=crlf"
407        case.
408    
409    44. Added a number of casts and did some reorganization of signed/unsigned int
410        variables following suggestions from Dair Grant. Also renamed the variable
411        "this" as "item" because it is a C++ keyword.
412    
413    45. Arranged for dftables to add
414    
415          #include "pcre_internal.h"
416    
417        to pcre_chartables.c because without it, gcc 4.x may remove the array
418        definition from the final binary if PCRE is built into a static library and
419        dead code stripping is activated.
420    
421    46. For an unanchored pattern, if a match attempt fails at the start of a
422        newline sequence, and the newline setting is CRLF or ANY, and the next two
423        characters are CRLF, advance by two characters instead of one.
424    
425    
426    Version 6.7 04-Jul-06
427    ---------------------
428    
429     1. In order to handle tests when input lines are enormously long, pcretest has
430        been re-factored so that it automatically extends its buffers when
431        necessary. The code is crude, but this _is_ just a test program. The
432        default size has been increased from 32K to 50K.
433    
434     2. The code in pcre_study() was using the value of the re argument before
435        testing it for NULL. (Of course, in any sensible call of the function, it
436        won't be NULL.)
437    
438     3. The memmove() emulation function in pcre_internal.h, which is used on
439        systems that lack both memmove() and bcopy() - that is, hardly ever -
440        was missing a "static" storage class specifier.
441    
442     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
443        containing an extended class (one that cannot be represented by a bitmap
444        because it contains high-valued characters or Unicode property items, e.g.
445        [\pZ]). Almost always one would set UTF-8 mode when processing such a
446        pattern, but PCRE should not loop if you do not (it no longer does).
447        [Detail: two cases were found: (a) a repeated subpattern containing an
448        extended class; (b) a recursive reference to a subpattern that followed a
449        previous extended class. It wasn't skipping over the extended class
450        correctly when UTF-8 mode was not set.]
451    
452     5. A negated single-character class was not being recognized as fixed-length
453        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
454        compile error "lookbehind assertion is not fixed length".
455    
456     6. The RunPerlTest auxiliary script was showing an unexpected difference
457        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
458        write a Perl script that can interpret lines of an input file either as
459        byte characters or as UTF-8, which is what "perltest" was being required to
460        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
461        can't do is switch easily at run time between having the "use utf8;" pragma
462        or not. In the end, I fudged it by using the RunPerlTest script to insert
463        "use utf8;" explicitly for the UTF-8 tests.
464    
465     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
466        the end of the subject string, contrary to the documentation and to what
467        Perl does. This was true of both matching functions. Now it matches only at
468        the start of the subject and immediately after *internal* newlines.
469    
470     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
471        a pointer to an int instead of a pointer to an unsigned long int. This
472        caused problems on 64-bit systems.
473    
474     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
475        instance of the 'standard' template library not being so standard".
476    
477    10. There was no check on the number of named subpatterns nor the maximum
478        length of a subpattern name. The product of these values is used to compute
479        the size of the memory block for a compiled pattern. By supplying a very
480        long subpattern name and a large number of named subpatterns, the size
481        computation could be caused to overflow. This is now prevented by limiting
482        the length of names to 32 characters, and the number of named subpatterns
483        to 10,000.
484    
485    11. Subpatterns that are repeated with specific counts have to be replicated in
486        the compiled pattern. The size of memory for this was computed from the
487        length of the subpattern and the repeat count. The latter is limited to
488        65535, but there was no limit on the former, meaning that integer overflow
489        could in principle occur. The compiled length of a repeated subpattern is
490        now limited to 30,000 bytes in order to prevent this.
491    
492    12. Added the optional facility to have named substrings with the same name.
493    
494    13. Added the ability to use a named substring as a condition, using the
495        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
496        are numbers (not recommended). Forward references are permitted.
497    
498    14. Added forward references in named backreferences (if you see what I mean).
499    
500    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
501        pattern could run off the end of the subject. For example, the pattern
502        "(?s)(.{1,5})"8 did this with the subject "ab".
503    
504    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
505        PCRE_CASELESS was set when matching characters that were quantified with ?
506        or *.
507    
508    17. A character class other than a single negated character that had a minimum
509        but no maximum quantifier - for example [ab]{6,} - was not handled
510        correctly by pce_dfa_exec(). It would match only one character.
511    
512    18. A valid (though odd) pattern that looked like a POSIX character
513        class but used an invalid character after [ (for example [[,abc,]]) caused
514        pcre_compile() to give the error "Failed: internal error: code overflow" or
515        in some cases to crash with a glibc free() error. This could even happen if
516        the pattern terminated after [[ but there just happened to be a sequence of
517        letters, a binary zero, and a closing ] in the memory that followed.
518    
519    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
520        over the years. Originally (before any Unicode support), just the bottom 8
521        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
522        output from "man perlunicode" includes this:
523    
524          The regular expression compiler produces polymorphic opcodes.  That
525          is, the pattern adapts to the data and automatically switches to
526          the Unicode character scheme when presented with Unicode data--or
527          instead uses a traditional byte scheme when presented with byte
528          data.
529    
530        Sadly, a wide octal escape does not cause a switch, and in a string with
531        no other multibyte characters, these octal escapes are treated as before.
532        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
533        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
534        Unicode string.
535    
536        I have not perpetrated such confusion in PCRE. Up till now, it took just
537        the bottom 8 bits, as in old Perl. I have now made octal escapes with
538        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
539        translate to the appropriate multibyte character.
540    
541    29. Applied some refactoring to reduce the number of warnings from Microsoft
542        and Borland compilers. This has included removing the fudge introduced
543        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
544        a warning about an unused variable.
545    
546    21. PCRE has not included VT (character 0x0b) in the set of whitespace
547        characters since release 4.0, because Perl (from release 5.004) does not.
548        [Or at least, is documented not to: some releases seem to be in conflict
549        with the documentation.] However, when a pattern was studied with
550        pcre_study() and all its branches started with \s, PCRE still included VT
551        as a possible starting character. Of course, this did no harm; it just
552        caused an unnecessary match attempt.
553    
554    22. Removed a now-redundant internal flag bit that recorded the fact that case
555        dependency changed within the pattern. This was once needed for "required
556        byte" processing, but is no longer used. This recovers a now-scarce options
557        bit. Also moved the least significant internal flag bit to the most-
558        significant bit of the word, which was not previously used (hangover from
559        the days when it was an int rather than a uint) to free up another bit for
560        the future.
561    
562    23. Added support for CRLF line endings as well as CR and LF. As well as the
563        default being selectable at build time, it can now be changed at runtime
564        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
565        specify that it is scanning data with non-default line endings.
566    
567    24. Changed the definition of CXXLINK to make it agree with the definition of
568        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
569    
570    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
571        recursions. This makes a big different to stack usage for some patterns.
572    
573    26. If a subpattern containing a named recursion or subroutine reference such
574        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
575        the space required for the compiled pattern went wrong and gave too small a
576        value. Depending on the environment, this could lead to "Failed: internal
577        error: code overflow at offset 49" or "glibc detected double free or
578        corruption" errors.
579    
580    27. Applied patches from Google (a) to support the new newline modes and (b) to
581        advance over multibyte UTF-8 characters in GlobalReplace.
582    
583    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
584        difference for some implementation of PCRE in some Windows version.
585    
586    29. Added some extra testing facilities to pcretest:
587    
588        \q<number>   in a data line sets the "match limit" value
589        \Q<number>   in a data line sets the "match recursion limt" value
590        -S <number>  sets the stack size, where <number> is in megabytes
591    
592        The -S option isn't available for Windows.
593    
594    
595    Version 6.6 06-Feb-06
596    ---------------------
597    
598     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
599        in pcreposix.h. I have copied the definition from pcre.h.
600    
601     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
602        because pcre.h is no longer a built file.
603    
604     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
605        not normally included in the compiled code.
606    
607    
608    Version 6.5 01-Feb-06
609    ---------------------
610    
611     1. When using the partial match feature with pcre_dfa_exec(), it was not
612        anchoring the second and subsequent partial matches at the new starting
613        point. This could lead to incorrect results. For example, with the pattern
614        /1234/, partially matching against "123" and then "a4" gave a match.
615    
616     2. Changes to pcregrep:
617    
618        (a) All non-match returns from pcre_exec() were being treated as failures
619            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
620            error message is output. Some extra information is given for the
621            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
622            probably the only errors that are likely to be caused by users (by
623            specifying a regex that has nested indefinite repeats, for instance).
624            If there are more than 20 of these errors, pcregrep is abandoned.
625    
626        (b) A binary zero was treated as data while matching, but terminated the
627            output line if it was written out. This has been fixed: binary zeroes
628            are now no different to any other data bytes.
629    
630        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
631            used to set a locale for matching. The --locale=xxxx long option has
632            been added (no short equivalent) to specify a locale explicitly on the
633            pcregrep command, overriding the environment variables.
634    
635        (d) When -B was used with -n, some line numbers in the output were one less
636            than they should have been.
637    
638        (e) Added the -o (--only-matching) option.
639    
640        (f) If -A or -C was used with -c (count only), some lines of context were
641            accidentally printed for the final match.
642    
643        (g) Added the -H (--with-filename) option.
644    
645        (h) The combination of options -rh failed to suppress file names for files
646            that were found from directory arguments.
647    
648        (i) Added the -D (--devices) and -d (--directories) options.
649    
650        (j) Added the -F (--fixed-strings) option.
651    
652        (k) Allow "-" to be used as a file name for -f as well as for a data file.
653    
654        (l) Added the --colo(u)r option.
655    
656        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
657            is not present by default.
658    
659     3. A nasty bug was discovered in the handling of recursive patterns, that is,
660        items such as (?R) or (?1), when the recursion could match a number of
661        alternatives. If it matched one of the alternatives, but subsequently,
662        outside the recursion, there was a failure, the code tried to back up into
663        the recursion. However, because of the way PCRE is implemented, this is not
664        possible, and the result was an incorrect result from the match.
665    
666        In order to prevent this happening, the specification of recursion has
667        been changed so that all such subpatterns are automatically treated as
668        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
669    
670     4. I had overlooked the fact that, in some locales, there are characters for
671        which isalpha() is true but neither isupper() nor islower() are true. In
672        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
673        and ordfeminine) are like this. This affected the treatment of \w and \W
674        when they appeared in character classes, but not when they appeared outside
675        a character class. The bit map for "word" characters is now created
676        separately from the results of isalnum() instead of just taking it from the
677        upper, lower, and digit maps. (Plus the underscore character, of course.)
678    
679     5. The above bug also affected the handling of POSIX character classes such as
680        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
681        permanent tables. Instead, the bit maps for such a class were previously
682        created as the appropriate unions of the upper, lower, and digit bitmaps.
683        Now they are created by subtraction from the [[:word:]] class, which has
684        its own bitmap.
685    
686     6. The [[:blank:]] character class matches horizontal, but not vertical space.
687        It is created by subtracting the vertical space characters (\x09, \x0a,
688        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
689        subtraction was done in the overall bitmap for a character class, meaning
690        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
691        be recognized. This bug has been fixed.
692    
693     7. Patches from the folks at Google:
694    
695          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
696          real life, but is still worth protecting against".
697    
698          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
699          regular expressions".
700    
701          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
702          have it.
703    
704          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
705          "configure" and the latter not, in order to fix a problem somebody had
706          with compiling the Arg class on HP-UX.
707    
708          (e) Improve the error-handling of the C++ wrapper a little bit.
709    
710          (f) New tests for checking recursion limiting.
711    
712     8. The pcre_memmove() function, which is used only if the environment does not
713        have a standard memmove() function (and is therefore rarely compiled),
714        contained two bugs: (a) use of int instead of size_t, and (b) it was not
715        returning a result (though PCRE never actually uses the result).
716    
717     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
718        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
719        returned instead of calling malloc() with an overflowing number that would
720        most likely cause subsequent chaos.
721    
722    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
723    
724    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
725        with this option is matched, the nmatch and pmatch options of regexec() are
726        ignored.
727    
728    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
729        provided in case anyone wants to the the POSIX interface with UTF-8
730        strings.
731    
732    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
733        C++ linking (needed for some HP-UX environments).
734    
735    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
736        (unused parameter) and in the pcre_printint() function (omitted "default"
737        switch label when the default is to do nothing).
738    
739    15. Added some code to make it possible, when PCRE is compiled as a C++
740        library, to replace subject pointers for pcre_exec() with a smart pointer
741        class, thus making it possible to process discontinuous strings.
742    
743    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
744        much the same function. They were added by different people who were trying
745        to make PCRE easy to compile on non-Unix systems. It has been suggested
746        that PCRE_EXPORT be abolished now that there is more automatic apparatus
747        for compiling on Windows systems. I have therefore replaced it with
748        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
749        defaults to "extern" for C or "extern C" for C++, which works fine on
750        Unix-like systems. It is now possible to override the value of PCRE_DATA_
751        SCOPE with something explicit in config.h. In addition:
752    
753        (a) pcreposix.h still had just "extern" instead of either of these macros;
754            I have replaced it with PCRE_DATA_SCOPE.
755    
756        (b) Functions such as _pcre_xclass(), which are internal to the library,
757            but external in the C sense, all had PCRE_EXPORT in their definitions.
758            This is apparently wrong for the Windows case, so I have removed it.
759            (It makes no difference on Unix-like systems.)
760    
761    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
762        of recursive calls to match(). This is different to MATCH_LIMIT because
763        that limits the total number of calls to match(), not all of which increase
764        the depth of recursion. Limiting the recursion depth limits the amount of
765        stack (or heap if NO_RECURSE is set) that is used. The default can be set
766        when PCRE is compiled, and changed at run time. A patch from Google adds
767        this functionality to the C++ interface.
768    
769    18. Changes to the handling of Unicode character properties:
770    
771        (a) Updated the table to Unicode 4.1.0.
772    
773        (b) Recognize characters that are not in the table as "Cn" (undefined).
774    
775        (c) I revised the way the table is implemented to a much improved format
776            which includes recognition of ranges. It now supports the ranges that
777            are defined in UnicodeData.txt, and it also amalgamates other
778            characters into ranges. This has reduced the number of entries in the
779            table from around 16,000 to around 3,000, thus reducing its size
780            considerably. I realized I did not need to use a tree structure after
781            all - a binary chop search is just as efficient. Having reduced the
782            number of entries, I extended their size from 6 bytes to 8 bytes to
783            allow for more data.
784    
785        (d) Added support for Unicode script names via properties such as \p{Han}.
786    
787    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
788        matching that character.
789    
790    20. When matching a repeated Unicode property with a minimum greater than zero,
791        (for example \pL{2,}), PCRE could look past the end of the subject if it
792        reached it while seeking the minimum number of characters. This could
793        happen only if some of the characters were more than one byte long, because
794        there is a check for at least the minimum number of bytes.
795    
796    21. Refactored the implementation of \p and \P so as to be more general, to
797        allow for more different types of property in future. This has changed the
798        compiled form incompatibly. Anybody with saved compiled patterns that use
799        \p or \P will have to recompile them.
800    
801    22. Added "Any" and "L&" to the supported property types.
802    
803    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
804        but give a compile time error if the value is greater than 0xff.
805    
806    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
807        accidentally not being installed or uninstalled.
808    
809    25. The pcre.h file was built from pcre.h.in, but the only changes that were
810        made were to insert the current release number. This seemed silly, because
811        it made things harder for people building PCRE on systems that don't run
812        "configure". I have turned pcre.h into a distributed file, no longer built
813        by "configure", with the version identification directly included. There is
814        no longer a pcre.h.in file.
815    
816        However, this change necessitated a change to the pcre-config script as
817        well. It is built from pcre-config.in, and one of the substitutions was the
818        release number. I have updated configure.ac so that ./configure now finds
819        the release number by grepping pcre.h.
820    
821    26. Added the ability to run the tests under valgrind.
822    
823    
824    Version 6.4 05-Sep-05
825    ---------------------
826    
827     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
828        "--" to be printed when multiple files were scanned, even when none of the
829        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
830        consider it to be a bug, and have restored the previous behaviour.
831    
832     2. A couple of code tidies to get rid of compiler warnings.
833    
834     3. The pcretest program used to cheat by referring to symbols in the library
835        whose names begin with _pcre_. These are internal symbols that are not
836        really supposed to be visible externally, and in some environments it is
837        possible to suppress them. The cheating is now confined to including
838        certain files from the library's source, which is a bit cleaner.
839    
840     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
841        file's purpose clearer.
842    
843     5. Reorganized pcre_ucp_findchar().
844    
845    
846    Version 6.3 15-Aug-05
847    ---------------------
848    
849     1. The file libpcre.pc.in did not have general read permission in the tarball.
850    
851     2. There were some problems when building without C++ support:
852    
853        (a) If C++ support was not built, "make install" and "make test" still
854            tried to test it.
855    
856        (b) There were problems when the value of CXX was explicitly set. Some
857            changes have been made to try to fix these, and ...
858    
859        (c) --disable-cpp can now be used to explicitly disable C++ support.
860    
861        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
862            backslash in a target when C++ was disabled. This confuses some
863            versions of "make", apparently. Using an intermediate variable solves
864            this. (Same for CPP_LOBJ.)
865    
866     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
867        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
868        necessary on certain architectures.
869    
870     4. Added a setting of -export-symbols-regex to the link command to remove
871        those symbols that are exported in the C sense, but actually are local
872        within the library, and not documented. Their names all begin with
873        "_pcre_". This is not a perfect job, because (a) we have to except some
874        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
875        available (and never for static libraries). I have made a note to try to
876        find a way round (a) in the future.
877    
878    
879  Version 6.2 01-Aug-05  Version 6.2 01-Aug-05
880  ---------------------  ---------------------
881    

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