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revision 77 by nigel, Sat Feb 24 21:40:45 2007 UTC revision 167 by ph10, Wed May 9 15:53:54 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.2 01-May-07
5    ---------------------
6    
7     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
8        which is apparently normally available under Windows.
9    
10     2. Re-jig the pcregrep tests with different newline settings in an attempt
11        to make them independent of the local environment's newline setting.
12    
13     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
14    
15     4. Some of the "internals" tests were previously cut out when the link size
16        was not 2, because the output contained actual offsets. The recent new
17        "Z" feature of pcretest means that these can be cut out, making the tests
18        usable with all link sizes.
19    
20     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
21        stack recursion. This gives a massive performance boost under BSD, but just
22        a small improvement under Linux. However, it saves one field in the frame
23        in all cases.
24    
25     6. Added more features from the forthcoming Perl 5.10:
26    
27        (a) (?-n) (where n is a string of digits) is a relative subroutine or
28            recursion call. It refers to the nth most recently opened parentheses.
29    
30        (b) (?+n) is also a relative subroutine call; it refers to the nth next
31            to be opened parentheses.
32    
33        (c) Conditions that refer to capturing parentheses can be specified
34            relatively, for example, (?(-2)... or (?(+3)...
35    
36    
37    Version 7.1 24-Apr-07
38    ---------------------
39    
40     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
41        that is more "standard", making use of automake and other Autotools. There
42        is some re-arrangement of the files and adjustment of comments consequent
43        on this.
44    
45     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
46        for recursive directory scanning broke on some systems because the files
47        are not scanned in any specific order and on different systems the order
48        was different. A call to "sort" has been inserted into RunGrepTest for the
49        approprate test as a short-term fix. In the longer term there may be an
50        alternative.
51    
52     3. I had an email from Eric Raymond about problems translating some of PCRE's
53        man pages to HTML (despite the fact that I distribute HTML pages, some
54        people do their own conversions for various reasons). The problems
55        concerned the use of low-level troff macros .br and .in. I have therefore
56        removed all such uses from the man pages (some were redundant, some could
57        be replaced by .nf/.fi pairs). The 132html script that I use to generate
58        HTML has been updated to handle .nf/.fi and to complain if it encounters
59        .br or .in.
60    
61     4. Updated comments in configure.ac that get placed in config.h.in and also
62        arranged for config.h to be included in the distribution, with the name
63        config.h.generic, for the benefit of those who have to compile without
64        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
65    
66     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
67        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
68        makevp.bat for the current PCRE, using the additional files
69        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
70    
71     6. A Windows user reported a minor discrepancy with test 2, which turned out
72        to be caused by a trailing space on an input line that had got lost in his
73        copy. The trailing space was an accident, so I've just removed it.
74    
75     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
76        that is needed.
77    
78     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
79        as "const" (a) because they are and (b) because it helps the PHP
80        maintainers who have recently made a script to detect big data structures
81        in the php code that should be moved to the .rodata section. I remembered
82        to update Builducptable as well, so it won't revert if ucptable.h is ever
83        re-created.
84    
85     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
86        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
87        order to be able to cut out the UTF-8 tables in the latter when UTF-8
88        support is not required. This saves 1.5-2K of code, which is important in
89        some applications.
90    
91        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
92        so as not to refer to the tables, even though these functions will never be
93        called when UTF-8 support is disabled. Otherwise there are problems with a
94        shared library.
95    
96    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
97    
98        (a) It was defining its arguments as char * instead of void *.
99    
100        (b) It was assuming that all moves were upwards in memory; this was true
101            a long time ago when I wrote it, but is no longer the case.
102    
103        The emulated memove() is provided for those environments that have neither
104        memmove() nor bcopy(). I didn't think anyone used it these days, but that
105        is clearly not the case, as these two bugs were recently reported.
106    
107    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
108        and Detrail to create the HTML documentation, the .txt form of the man
109        pages, and it removes trailing spaces from listed files. It also creates
110        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
111        case, it wraps all the #defines with #ifndefs. This script should be run
112        before "make dist".
113    
114    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
115        with Unicode property support.
116    
117        (a) For a maximizing quantifier, if the two different cases of the
118            character were of different lengths in their UTF-8 codings (there are
119            some cases like this - I found 11), and the matching function had to
120            back up over a mixture of the two cases, it incorrectly assumed they
121            were both the same length.
122    
123        (b) When PCRE was configured to use the heap rather than the stack for
124            recursion during matching, it was not correctly preserving the data for
125            the other case of a UTF-8 character when checking ahead for a match
126            while processing a minimizing repeat. If the check also involved
127            matching a wide character, but failed, corruption could cause an
128            erroneous result when trying to check for a repeat of the original
129            character.
130    
131    13. Some tidying changes to the testing mechanism:
132    
133        (a) The RunTest script now detects the internal link size and whether there
134            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
135            values substituted by "configure". (The RunGrepTest script already did
136            this for UTF-8.) The configure.ac script no longer substitutes the
137            relevant variables.
138    
139        (b) The debugging options /B and /D in pcretest show the compiled bytecode
140            with length and offset values. This means that the output is different
141            for different internal link sizes. Test 2 is skipped for link sizes
142            other than 2 because of this, bypassing the problem. Unfortunately,
143            there was also a test in test 3 (the locale tests) that used /B and
144            failed for link sizes other than 2. Rather than cut the whole test out,
145            I have added a new /Z option to pcretest that replaces the length and
146            offset values with spaces. This is now used to make test 3 independent
147            of link size. (Test 2 will be tidied up later.)
148    
149    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
150        segmentation fault instead of returning the appropriate error message.
151    
152    15. In multiline mode when the newline sequence was set to "any", the pattern
153        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
154        This doesn't seem right; it now treats the CRLF combination as the line
155        ending, and so does not match in that case. It's only a pattern such as ^$
156        that would hit this one: something like ^ABC$ would have failed after \r
157        and then tried again after \r\n.
158    
159    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
160        in an attempt to make files that differ only in their line terminators
161        compare equal. This works on Linux.
162    
163    17. Under certain error circumstances pcregrep might try to free random memory
164        as it exited. This is now fixed, thanks to valgrind.
165    
166    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
167        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
168        was because its rules for how to advance for /g after matching an empty
169        string at the end of a line did not allow for this case. They now check for
170        it specially.
171    
172    20. pcretest is supposed to handle patterns and data of any length, by
173        extending its buffers when necessary. It was getting this wrong when the
174        buffer for a data line had to be extended.
175    
176    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
177        CRLF as a newline sequence.
178    
179    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
180        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
181        I have nevertheless tidied it up.
182    
183    23. Added some casts to kill warnings from HP-UX ia64 compiler.
184    
185    24. Added a man page for pcre-config.
186    
187    
188    Version 7.0 19-Dec-06
189    ---------------------
190    
191     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
192        moving to gcc 4.1.1.
193    
194     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
195        sys/time.h, which is documented as needed for this function. It doesn't
196        seem to matter on Linux, but it showed up on some releases of OS X.
197    
198     3. It seems that there are systems where bytes whose values are greater than
199        127 match isprint() in the "C" locale. The "C" locale should be the
200        default when a C program starts up. In most systems, only ASCII printing
201        characters match isprint(). This difference caused the output from pcretest
202        to vary, making some of the tests fail. I have changed pcretest so that:
203    
204        (a) When it is outputting text in the compiled version of a pattern, bytes
205            other than 32-126 are always shown as hex escapes.
206    
207        (b) When it is outputting text that is a matched part of a subject string,
208            it does the same, unless a different locale has been set for the match
209            (using the /L modifier). In this case, it uses isprint() to decide.
210    
211     4. Fixed a major bug that caused incorrect computation of the amount of memory
212        required for a compiled pattern when options that changed within the
213        pattern affected the logic of the preliminary scan that determines the
214        length. The relevant options are -x, and -i in UTF-8 mode. The result was
215        that the computed length was too small. The symptoms of this bug were
216        either the PCRE error "internal error: code overflow" from pcre_compile(),
217        or a glibc crash with a message such as "pcretest: free(): invalid next
218        size (fast)". Examples of patterns that provoked this bug (shown in
219        pcretest format) are:
220    
221          /(?-x: )/x
222          /(?x)(?-x: \s*#\s*)/
223          /((?i)[\x{c0}])/8
224          /(?i:[\x{c0}])/8
225    
226        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
227        is now done differently.
228    
229     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
230        wrapper classes; (b) implement a new function in the C++ scanner that is
231        more efficient than the old way of doing things because it avoids levels of
232        recursion in the regex matching; (c) add a paragraph to the documentation
233        for the FullMatch() function.
234    
235     6. The escape sequence \n was being treated as whatever was defined as
236        "newline". Not only was this contrary to the documentation, which states
237        that \n is character 10 (hex 0A), but it also went horribly wrong when
238        "newline" was defined as CRLF. This has been fixed.
239    
240     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
241        was being set to -1 for the "end of line" case (supposedly a value that no
242        character can have). Though this value is never used (the check for end of
243        line is "zero bytes in current character"), it caused compiler complaints.
244        I've changed it to 0xffffffff.
245    
246     8. In pcre_version.c, the version string was being built by a sequence of
247        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
248        string (as it is for production releases) called a macro with an empty
249        argument. The C standard says the result of this is undefined. The gcc
250        compiler treats it as an empty string (which was what was wanted) but it is
251        reported that Visual C gives an error. The source has been hacked around to
252        avoid this problem.
253    
254     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
255        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
256        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
257        of them did).
258    
259    10. Originally, pcretest opened its input and output without "b"; then I was
260        told that "b" was needed in some environments, so it was added for release
261        5.0 to both the input and output. (It makes no difference on Unix-like
262        systems.) Later I was told that it is wrong for the input on Windows. I've
263        now abstracted the modes into two macros, to make it easier to fiddle with
264        them, and removed "b" from the input mode under Windows.
265    
266    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
267    
268    12. Added -help and --help to pcretest as an official way of being reminded
269        of the options.
270    
271    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
272        and pcrecpp.cc because they annoy compilers at high warning levels.
273    
274    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
275    
276    15. Fixed an occurrence of == in configure.ac that should have been = (shell
277        scripts are not C programs :-) and which was not noticed because it works
278        on Linux.
279    
280    16. pcretest is supposed to handle any length of pattern and data line (as one
281        line or as a continued sequence of lines) by extending its input buffer if
282        necessary. This feature was broken for very long pattern lines, leading to
283        a string of junk being passed to pcre_compile() if the pattern was longer
284        than about 50K.
285    
286    17. I have done a major re-factoring of the way pcre_compile() computes the
287        amount of memory needed for a compiled pattern. Previously, there was code
288        that made a preliminary scan of the pattern in order to do this. That was
289        OK when PCRE was new, but as the facilities have expanded, it has become
290        harder and harder to keep it in step with the real compile phase, and there
291        have been a number of bugs (see for example, 4 above). I have now found a
292        cunning way of running the real compile function in a "fake" mode that
293        enables it to compute how much memory it would need, while actually only
294        ever using a few hundred bytes of working memory and without too many
295        tests of the mode. This should make future maintenance and development
296        easier. A side effect of this work is that the limit of 200 on the nesting
297        depth of parentheses has been removed (though this was never a serious
298        limitation, I suspect). However, there is a downside: pcre_compile() now
299        runs more slowly than before (30% or more, depending on the pattern). I
300        hope this isn't a big issue. There is no effect on runtime performance.
301    
302    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
303        newline (only possible for the last line of a file) and it was a
304        pattern that set a locale (followed by /Lsomething), pcretest crashed.
305    
306    19. Added additional timing features to pcretest. (1) The -tm option now times
307        matching only, not compiling. (2) Both -t and -tm can be followed, as a
308        separate command line item, by a number that specifies the number of
309        repeats to use when timing. The default is 50000; this gives better
310        precision, but takes uncomfortably long for very large patterns.
311    
312    20. Extended pcre_study() to be more clever in cases where a branch of a
313        subpattern has no definite first character. For example, (a*|b*)[cd] would
314        previously give no result from pcre_study(). Now it recognizes that the
315        first character must be a, b, c, or d.
316    
317    21. There was an incorrect error "recursive call could loop indefinitely" if
318        a subpattern (or the entire pattern) that was being tested for matching an
319        empty string contained only one non-empty item after a nested subpattern.
320        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
321        incorrectly, because the \d was being skipped in the check.
322    
323    22. The pcretest program now has a new pattern option /B and a command line
324        option -b, which is equivalent to adding /B to every pattern. This causes
325        it to show the compiled bytecode, without the additional information that
326        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
327        is the same as /B/I).
328    
329    23. A new optimization is now able automatically to treat some sequences such
330        as a*b as a*+b. More specifically, if something simple (such as a character
331        or a simple class like \d) has an unlimited quantifier, and is followed by
332        something that cannot possibly match the quantified thing, the quantifier
333        is automatically "possessified".
334    
335    24. A recursive reference to a subpattern whose number was greater than 39
336        went wrong under certain circumstances in UTF-8 mode. This bug could also
337        have affected the operation of pcre_study().
338    
339    25. Realized that a little bit of performance could be had by replacing
340        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
341    
342    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
343    
344    27. Possessive quantifiers such as a++ were previously implemented by turning
345        them into atomic groups such as ($>a+). Now they have their own opcodes,
346        which improves performance. This includes the automatically created ones
347        from 23 above.
348    
349    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
350        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
351        the first matched character to be a colon. This applied both to named and
352        numbered groups.
353    
354    29. The ucpinternal.h header file was missing its idempotency #ifdef.
355    
356    30. I was sent a "project" file called libpcre.a.dev which I understand makes
357        building PCRE on Windows easier, so I have included it in the distribution.
358    
359    31. There is now a check in pcretest against a ridiculously large number being
360        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
361        loop, the loop is abandoned.
362    
363    32. Forward references to subpatterns in conditions such as (?(2)...) where
364        subpattern 2 is defined later cause pcre_compile() to search forwards in
365        the pattern for the relevant set of parentheses. This search went wrong
366        when there were unescaped parentheses in a character class, parentheses
367        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
368    
369    33. "Subroutine" calls and backreferences were previously restricted to
370        referencing subpatterns earlier in the regex. This restriction has now
371        been removed.
372    
373    34. Added a number of extra features that are going to be in Perl 5.10. On the
374        whole, these are just syntactic alternatives for features that PCRE had
375        previously implemented using the Python syntax or my own invention. The
376        other formats are all retained for compatibility.
377    
378        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
379            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
380            also .NET compatible.
381    
382        (b) A recursion or subroutine call to a named group can now be defined as
383            (?&name) as well as (?P>name).
384    
385        (c) A backreference to a named group can now be defined as \k<name> or
386            \k'name' as well as (?P=name). The new forms, as well as being in Perl
387            5.10, are also .NET compatible.
388    
389        (d) A conditional reference to a named group can now use the syntax
390            (?(<name>) or (?('name') as well as (?(name).
391    
392        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
393            groups (named and numbered) that are never evaluated inline, but can be
394            called as "subroutines" from elsewhere. In effect, the DEFINE condition
395            is always false. There may be only one alternative in such a group.
396    
397        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
398            as the simple (?(R). The condition is true only if the most recent
399            recursion is that of the given number or name. It does not search out
400            through the entire recursion stack.
401    
402        (g) The escape \gN or \g{N} has been added, where N is a positive or
403            negative number, specifying an absolute or relative reference.
404    
405    35. Tidied to get rid of some further signed/unsigned compiler warnings and
406        some "unreachable code" warnings.
407    
408    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
409        things, this adds five new scripts.
410    
411    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
412        There were also incompatibilities regarding the handling of \Q..\E inside
413        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
414        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
415    
416    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
417        matches an empty string, and forcibly breaks the loop. There were bugs in
418        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
419        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
420        separate and independent bugs (that affected different cases) have been
421        fixed.
422    
423    39. Refactored the code to abolish the use of different opcodes for small
424        capturing bracket numbers. This is a tidy that I avoided doing when I
425        removed the limit on the number of capturing brackets for 3.5 back in 2001.
426        The new approach is not only tidier, it makes it possible to reduce the
427        memory needed to fix the previous bug (38).
428    
429    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
430        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
431        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
432        mode.
433    
434    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
435        report.
436    
437    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
438        copy construction and assignment in the C++ wrapper.
439    
440    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
441        couple of bugs that could have given wrong results in the "--newline=crlf"
442        case.
443    
444    44. Added a number of casts and did some reorganization of signed/unsigned int
445        variables following suggestions from Dair Grant. Also renamed the variable
446        "this" as "item" because it is a C++ keyword.
447    
448    45. Arranged for dftables to add
449    
450          #include "pcre_internal.h"
451    
452        to pcre_chartables.c because without it, gcc 4.x may remove the array
453        definition from the final binary if PCRE is built into a static library and
454        dead code stripping is activated.
455    
456    46. For an unanchored pattern, if a match attempt fails at the start of a
457        newline sequence, and the newline setting is CRLF or ANY, and the next two
458        characters are CRLF, advance by two characters instead of one.
459    
460    
461    Version 6.7 04-Jul-06
462    ---------------------
463    
464     1. In order to handle tests when input lines are enormously long, pcretest has
465        been re-factored so that it automatically extends its buffers when
466        necessary. The code is crude, but this _is_ just a test program. The
467        default size has been increased from 32K to 50K.
468    
469     2. The code in pcre_study() was using the value of the re argument before
470        testing it for NULL. (Of course, in any sensible call of the function, it
471        won't be NULL.)
472    
473     3. The memmove() emulation function in pcre_internal.h, which is used on
474        systems that lack both memmove() and bcopy() - that is, hardly ever -
475        was missing a "static" storage class specifier.
476    
477     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
478        containing an extended class (one that cannot be represented by a bitmap
479        because it contains high-valued characters or Unicode property items, e.g.
480        [\pZ]). Almost always one would set UTF-8 mode when processing such a
481        pattern, but PCRE should not loop if you do not (it no longer does).
482        [Detail: two cases were found: (a) a repeated subpattern containing an
483        extended class; (b) a recursive reference to a subpattern that followed a
484        previous extended class. It wasn't skipping over the extended class
485        correctly when UTF-8 mode was not set.]
486    
487     5. A negated single-character class was not being recognized as fixed-length
488        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
489        compile error "lookbehind assertion is not fixed length".
490    
491     6. The RunPerlTest auxiliary script was showing an unexpected difference
492        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
493        write a Perl script that can interpret lines of an input file either as
494        byte characters or as UTF-8, which is what "perltest" was being required to
495        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
496        can't do is switch easily at run time between having the "use utf8;" pragma
497        or not. In the end, I fudged it by using the RunPerlTest script to insert
498        "use utf8;" explicitly for the UTF-8 tests.
499    
500     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
501        the end of the subject string, contrary to the documentation and to what
502        Perl does. This was true of both matching functions. Now it matches only at
503        the start of the subject and immediately after *internal* newlines.
504    
505     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
506        a pointer to an int instead of a pointer to an unsigned long int. This
507        caused problems on 64-bit systems.
508    
509     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
510        instance of the 'standard' template library not being so standard".
511    
512    10. There was no check on the number of named subpatterns nor the maximum
513        length of a subpattern name. The product of these values is used to compute
514        the size of the memory block for a compiled pattern. By supplying a very
515        long subpattern name and a large number of named subpatterns, the size
516        computation could be caused to overflow. This is now prevented by limiting
517        the length of names to 32 characters, and the number of named subpatterns
518        to 10,000.
519    
520    11. Subpatterns that are repeated with specific counts have to be replicated in
521        the compiled pattern. The size of memory for this was computed from the
522        length of the subpattern and the repeat count. The latter is limited to
523        65535, but there was no limit on the former, meaning that integer overflow
524        could in principle occur. The compiled length of a repeated subpattern is
525        now limited to 30,000 bytes in order to prevent this.
526    
527    12. Added the optional facility to have named substrings with the same name.
528    
529    13. Added the ability to use a named substring as a condition, using the
530        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
531        are numbers (not recommended). Forward references are permitted.
532    
533    14. Added forward references in named backreferences (if you see what I mean).
534    
535    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
536        pattern could run off the end of the subject. For example, the pattern
537        "(?s)(.{1,5})"8 did this with the subject "ab".
538    
539    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
540        PCRE_CASELESS was set when matching characters that were quantified with ?
541        or *.
542    
543    17. A character class other than a single negated character that had a minimum
544        but no maximum quantifier - for example [ab]{6,} - was not handled
545        correctly by pce_dfa_exec(). It would match only one character.
546    
547    18. A valid (though odd) pattern that looked like a POSIX character
548        class but used an invalid character after [ (for example [[,abc,]]) caused
549        pcre_compile() to give the error "Failed: internal error: code overflow" or
550        in some cases to crash with a glibc free() error. This could even happen if
551        the pattern terminated after [[ but there just happened to be a sequence of
552        letters, a binary zero, and a closing ] in the memory that followed.
553    
554    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
555        over the years. Originally (before any Unicode support), just the bottom 8
556        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
557        output from "man perlunicode" includes this:
558    
559          The regular expression compiler produces polymorphic opcodes.  That
560          is, the pattern adapts to the data and automatically switches to
561          the Unicode character scheme when presented with Unicode data--or
562          instead uses a traditional byte scheme when presented with byte
563          data.
564    
565        Sadly, a wide octal escape does not cause a switch, and in a string with
566        no other multibyte characters, these octal escapes are treated as before.
567        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
568        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
569        Unicode string.
570    
571        I have not perpetrated such confusion in PCRE. Up till now, it took just
572        the bottom 8 bits, as in old Perl. I have now made octal escapes with
573        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
574        translate to the appropriate multibyte character.
575    
576    29. Applied some refactoring to reduce the number of warnings from Microsoft
577        and Borland compilers. This has included removing the fudge introduced
578        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
579        a warning about an unused variable.
580    
581    21. PCRE has not included VT (character 0x0b) in the set of whitespace
582        characters since release 4.0, because Perl (from release 5.004) does not.
583        [Or at least, is documented not to: some releases seem to be in conflict
584        with the documentation.] However, when a pattern was studied with
585        pcre_study() and all its branches started with \s, PCRE still included VT
586        as a possible starting character. Of course, this did no harm; it just
587        caused an unnecessary match attempt.
588    
589    22. Removed a now-redundant internal flag bit that recorded the fact that case
590        dependency changed within the pattern. This was once needed for "required
591        byte" processing, but is no longer used. This recovers a now-scarce options
592        bit. Also moved the least significant internal flag bit to the most-
593        significant bit of the word, which was not previously used (hangover from
594        the days when it was an int rather than a uint) to free up another bit for
595        the future.
596    
597    23. Added support for CRLF line endings as well as CR and LF. As well as the
598        default being selectable at build time, it can now be changed at runtime
599        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
600        specify that it is scanning data with non-default line endings.
601    
602    24. Changed the definition of CXXLINK to make it agree with the definition of
603        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
604    
605    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
606        recursions. This makes a big different to stack usage for some patterns.
607    
608    26. If a subpattern containing a named recursion or subroutine reference such
609        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
610        the space required for the compiled pattern went wrong and gave too small a
611        value. Depending on the environment, this could lead to "Failed: internal
612        error: code overflow at offset 49" or "glibc detected double free or
613        corruption" errors.
614    
615    27. Applied patches from Google (a) to support the new newline modes and (b) to
616        advance over multibyte UTF-8 characters in GlobalReplace.
617    
618    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
619        difference for some implementation of PCRE in some Windows version.
620    
621    29. Added some extra testing facilities to pcretest:
622    
623        \q<number>   in a data line sets the "match limit" value
624        \Q<number>   in a data line sets the "match recursion limt" value
625        -S <number>  sets the stack size, where <number> is in megabytes
626    
627        The -S option isn't available for Windows.
628    
629    
630    Version 6.6 06-Feb-06
631    ---------------------
632    
633     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
634        in pcreposix.h. I have copied the definition from pcre.h.
635    
636     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
637        because pcre.h is no longer a built file.
638    
639     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
640        not normally included in the compiled code.
641    
642    
643    Version 6.5 01-Feb-06
644    ---------------------
645    
646     1. When using the partial match feature with pcre_dfa_exec(), it was not
647        anchoring the second and subsequent partial matches at the new starting
648        point. This could lead to incorrect results. For example, with the pattern
649        /1234/, partially matching against "123" and then "a4" gave a match.
650    
651     2. Changes to pcregrep:
652    
653        (a) All non-match returns from pcre_exec() were being treated as failures
654            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
655            error message is output. Some extra information is given for the
656            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
657            probably the only errors that are likely to be caused by users (by
658            specifying a regex that has nested indefinite repeats, for instance).
659            If there are more than 20 of these errors, pcregrep is abandoned.
660    
661        (b) A binary zero was treated as data while matching, but terminated the
662            output line if it was written out. This has been fixed: binary zeroes
663            are now no different to any other data bytes.
664    
665        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
666            used to set a locale for matching. The --locale=xxxx long option has
667            been added (no short equivalent) to specify a locale explicitly on the
668            pcregrep command, overriding the environment variables.
669    
670        (d) When -B was used with -n, some line numbers in the output were one less
671            than they should have been.
672    
673        (e) Added the -o (--only-matching) option.
674    
675        (f) If -A or -C was used with -c (count only), some lines of context were
676            accidentally printed for the final match.
677    
678        (g) Added the -H (--with-filename) option.
679    
680        (h) The combination of options -rh failed to suppress file names for files
681            that were found from directory arguments.
682    
683        (i) Added the -D (--devices) and -d (--directories) options.
684    
685        (j) Added the -F (--fixed-strings) option.
686    
687        (k) Allow "-" to be used as a file name for -f as well as for a data file.
688    
689        (l) Added the --colo(u)r option.
690    
691        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
692            is not present by default.
693    
694     3. A nasty bug was discovered in the handling of recursive patterns, that is,
695        items such as (?R) or (?1), when the recursion could match a number of
696        alternatives. If it matched one of the alternatives, but subsequently,
697        outside the recursion, there was a failure, the code tried to back up into
698        the recursion. However, because of the way PCRE is implemented, this is not
699        possible, and the result was an incorrect result from the match.
700    
701        In order to prevent this happening, the specification of recursion has
702        been changed so that all such subpatterns are automatically treated as
703        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
704    
705     4. I had overlooked the fact that, in some locales, there are characters for
706        which isalpha() is true but neither isupper() nor islower() are true. In
707        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
708        and ordfeminine) are like this. This affected the treatment of \w and \W
709        when they appeared in character classes, but not when they appeared outside
710        a character class. The bit map for "word" characters is now created
711        separately from the results of isalnum() instead of just taking it from the
712        upper, lower, and digit maps. (Plus the underscore character, of course.)
713    
714     5. The above bug also affected the handling of POSIX character classes such as
715        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
716        permanent tables. Instead, the bit maps for such a class were previously
717        created as the appropriate unions of the upper, lower, and digit bitmaps.
718        Now they are created by subtraction from the [[:word:]] class, which has
719        its own bitmap.
720    
721     6. The [[:blank:]] character class matches horizontal, but not vertical space.
722        It is created by subtracting the vertical space characters (\x09, \x0a,
723        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
724        subtraction was done in the overall bitmap for a character class, meaning
725        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
726        be recognized. This bug has been fixed.
727    
728     7. Patches from the folks at Google:
729    
730          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
731          real life, but is still worth protecting against".
732    
733          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
734          regular expressions".
735    
736          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
737          have it.
738    
739          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
740          "configure" and the latter not, in order to fix a problem somebody had
741          with compiling the Arg class on HP-UX.
742    
743          (e) Improve the error-handling of the C++ wrapper a little bit.
744    
745          (f) New tests for checking recursion limiting.
746    
747     8. The pcre_memmove() function, which is used only if the environment does not
748        have a standard memmove() function (and is therefore rarely compiled),
749        contained two bugs: (a) use of int instead of size_t, and (b) it was not
750        returning a result (though PCRE never actually uses the result).
751    
752     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
753        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
754        returned instead of calling malloc() with an overflowing number that would
755        most likely cause subsequent chaos.
756    
757    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
758    
759    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
760        with this option is matched, the nmatch and pmatch options of regexec() are
761        ignored.
762    
763    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
764        provided in case anyone wants to the the POSIX interface with UTF-8
765        strings.
766    
767    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
768        C++ linking (needed for some HP-UX environments).
769    
770    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
771        (unused parameter) and in the pcre_printint() function (omitted "default"
772        switch label when the default is to do nothing).
773    
774    15. Added some code to make it possible, when PCRE is compiled as a C++
775        library, to replace subject pointers for pcre_exec() with a smart pointer
776        class, thus making it possible to process discontinuous strings.
777    
778    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
779        much the same function. They were added by different people who were trying
780        to make PCRE easy to compile on non-Unix systems. It has been suggested
781        that PCRE_EXPORT be abolished now that there is more automatic apparatus
782        for compiling on Windows systems. I have therefore replaced it with
783        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
784        defaults to "extern" for C or "extern C" for C++, which works fine on
785        Unix-like systems. It is now possible to override the value of PCRE_DATA_
786        SCOPE with something explicit in config.h. In addition:
787    
788        (a) pcreposix.h still had just "extern" instead of either of these macros;
789            I have replaced it with PCRE_DATA_SCOPE.
790    
791        (b) Functions such as _pcre_xclass(), which are internal to the library,
792            but external in the C sense, all had PCRE_EXPORT in their definitions.
793            This is apparently wrong for the Windows case, so I have removed it.
794            (It makes no difference on Unix-like systems.)
795    
796    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
797        of recursive calls to match(). This is different to MATCH_LIMIT because
798        that limits the total number of calls to match(), not all of which increase
799        the depth of recursion. Limiting the recursion depth limits the amount of
800        stack (or heap if NO_RECURSE is set) that is used. The default can be set
801        when PCRE is compiled, and changed at run time. A patch from Google adds
802        this functionality to the C++ interface.
803    
804    18. Changes to the handling of Unicode character properties:
805    
806        (a) Updated the table to Unicode 4.1.0.
807    
808        (b) Recognize characters that are not in the table as "Cn" (undefined).
809    
810        (c) I revised the way the table is implemented to a much improved format
811            which includes recognition of ranges. It now supports the ranges that
812            are defined in UnicodeData.txt, and it also amalgamates other
813            characters into ranges. This has reduced the number of entries in the
814            table from around 16,000 to around 3,000, thus reducing its size
815            considerably. I realized I did not need to use a tree structure after
816            all - a binary chop search is just as efficient. Having reduced the
817            number of entries, I extended their size from 6 bytes to 8 bytes to
818            allow for more data.
819    
820        (d) Added support for Unicode script names via properties such as \p{Han}.
821    
822    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
823        matching that character.
824    
825    20. When matching a repeated Unicode property with a minimum greater than zero,
826        (for example \pL{2,}), PCRE could look past the end of the subject if it
827        reached it while seeking the minimum number of characters. This could
828        happen only if some of the characters were more than one byte long, because
829        there is a check for at least the minimum number of bytes.
830    
831    21. Refactored the implementation of \p and \P so as to be more general, to
832        allow for more different types of property in future. This has changed the
833        compiled form incompatibly. Anybody with saved compiled patterns that use
834        \p or \P will have to recompile them.
835    
836    22. Added "Any" and "L&" to the supported property types.
837    
838    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
839        but give a compile time error if the value is greater than 0xff.
840    
841    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
842        accidentally not being installed or uninstalled.
843    
844    25. The pcre.h file was built from pcre.h.in, but the only changes that were
845        made were to insert the current release number. This seemed silly, because
846        it made things harder for people building PCRE on systems that don't run
847        "configure". I have turned pcre.h into a distributed file, no longer built
848        by "configure", with the version identification directly included. There is
849        no longer a pcre.h.in file.
850    
851        However, this change necessitated a change to the pcre-config script as
852        well. It is built from pcre-config.in, and one of the substitutions was the
853        release number. I have updated configure.ac so that ./configure now finds
854        the release number by grepping pcre.h.
855    
856    26. Added the ability to run the tests under valgrind.
857    
858    
859    Version 6.4 05-Sep-05
860    ---------------------
861    
862     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
863        "--" to be printed when multiple files were scanned, even when none of the
864        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
865        consider it to be a bug, and have restored the previous behaviour.
866    
867     2. A couple of code tidies to get rid of compiler warnings.
868    
869     3. The pcretest program used to cheat by referring to symbols in the library
870        whose names begin with _pcre_. These are internal symbols that are not
871        really supposed to be visible externally, and in some environments it is
872        possible to suppress them. The cheating is now confined to including
873        certain files from the library's source, which is a bit cleaner.
874    
875     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
876        file's purpose clearer.
877    
878     5. Reorganized pcre_ucp_findchar().
879    
880    
881    Version 6.3 15-Aug-05
882    ---------------------
883    
884     1. The file libpcre.pc.in did not have general read permission in the tarball.
885    
886     2. There were some problems when building without C++ support:
887    
888        (a) If C++ support was not built, "make install" and "make test" still
889            tried to test it.
890    
891        (b) There were problems when the value of CXX was explicitly set. Some
892            changes have been made to try to fix these, and ...
893    
894        (c) --disable-cpp can now be used to explicitly disable C++ support.
895    
896        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
897            backslash in a target when C++ was disabled. This confuses some
898            versions of "make", apparently. Using an intermediate variable solves
899            this. (Same for CPP_LOBJ.)
900    
901     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
902        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
903        necessary on certain architectures.
904    
905     4. Added a setting of -export-symbols-regex to the link command to remove
906        those symbols that are exported in the C sense, but actually are local
907        within the library, and not documented. Their names all begin with
908        "_pcre_". This is not a perfect job, because (a) we have to except some
909        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
910        available (and never for static libraries). I have made a note to try to
911        find a way round (a) in the future.
912    
913    
914    Version 6.2 01-Aug-05
915    ---------------------
916    
917     1. There was no test for integer overflow of quantifier values. A construction
918        such as {1111111111111111} would give undefined results. What is worse, if
919        a minimum quantifier for a parenthesized subpattern overflowed and became
920        negative, the calculation of the memory size went wrong. This could have
921        led to memory overwriting.
922    
923     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
924    
925     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
926        operating environments where this matters.
927    
928     4. Applied Giuseppe Maxia's patch to add additional features for controlling
929        PCRE options from within the C++ wrapper.
930    
931     5. Named capturing subpatterns were not being correctly counted when a pattern
932        was compiled. This caused two problems: (a) If there were more than 100
933        such subpatterns, the calculation of the memory needed for the whole
934        compiled pattern went wrong, leading to an overflow error. (b) Numerical
935        back references of the form \12, where the number was greater than 9, were
936        not recognized as back references, even though there were sufficient
937        previous subpatterns.
938    
939     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
940        versions of gcc, e.g. 2.95.4.
941    
942    
943    Version 6.1 21-Jun-05
944    ---------------------
945    
946     1. There was one reference to the variable "posix" in pcretest.c that was not
947        surrounded by "#if !defined NOPOSIX".
948    
949     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
950        the cross-check on the old pcre_info() function, for the benefit of the
951        cut-down version of PCRE that is currently imported into Exim.
952    
953     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
954        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
955        patterns that start (?i) but I don't think that matters. The use of (?i) is
956        just an example; this all applies to the other options as well.
957    
958     4. Since libtool seems to echo the compile commands it is issuing, the output
959        from "make" can be reduced a bit by putting "@" in front of each libtool
960        compile command.
961    
962     5. Patch from the folks at Google for configure.in to be a bit more thorough
963        in checking for a suitable C++ installation before trying to compile the
964        C++ stuff. This should fix a reported problem when a compiler was present,
965        but no suitable headers.
966    
967     6. The man pages all had just "PCRE" as their title. I have changed them to
968        be the relevant file name. I have also arranged that these names are
969        retained in the file doc/pcre.txt, which is a concatenation in text format
970        of all the man pages except the little individual ones for each function.
971    
972     7. The NON-UNIX-USE file had not been updated for the different set of source
973        files that come with release 6. I also added a few comments about the C++
974        wrapper.
975    
976    
977  Version 6.0 07-Jun-05  Version 6.0 07-Jun-05
978  ---------------------  ---------------------
979    

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