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

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