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revision 73 by nigel, Sat Feb 24 21:40:30 2007 UTC revision 214 by ph10, Wed Aug 15 14:08:10 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.3 09-Aug-07
5    ---------------------
7     1. In the rejigging of the build system that eventually resulted in 7.1, the
8        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
9        brackets there is not right, since it causes compilers to look for an
10        installed pcre.h, not the version that is in the source that is being
11        compiled (which of course may be different). I have changed it back to:
13          #include "pcre.h"
15        I have a vague recollection that the change was concerned with compiling in
16        different directories, but in the new build system, that is taken care of
17        by the VPATH setting the Makefile.
19     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
20        when the subject happened to end in the byte 0x85 (e.g. if the last
21        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
22        characters but of course it shouldn't be taken as a newline when it is part
23        of another character. The bug was that, for an unlimited repeat of . in
24        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
25        characters when looking for a newline.
27     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
29     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
30        in debug output.
32     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
33        long printing in the pcrecpp unittest when running under MinGW.
35     6. ESC_K was left out of the EBCDIC table.
37     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
38        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
39        limit also applies to "virtual nesting" when a pattern is recursive, and in
40        this case 1000 isn't so big. I have been able to remove this limit at the
41        expense of backing off one optimization in certain circumstances. Normally,
42        when pcre_exec() would call its internal match() function recursively and
43        immediately return the result unconditionally, it uses a "tail recursion"
44        feature to save stack. However, when a subpattern that can match an empty
45        string has an unlimited repetition quantifier, it no longer makes this
46        optimization. That gives it a stack frame in which to save the data for
47        checking that an empty string has been matched. Previously this was taken
48        from the 1000-entry workspace that had been reserved. So now there is no
49        explicit limit, but more stack is used.
51     8. Applied Daniel's patches to solve problems with the import/export magic
52        syntax that is required for Windows, and which was going wrong for the
53        pcreposix and pcrecpp parts of the library. These were overlooked when this
54        problem was solved for the main library.
56     9. There were some crude static tests to avoid integer overflow when computing
57        the size of patterns that contain repeated groups with explicit upper
58        limits. As the maximum quantifier is 65535, the maximum group length was
59        set at 30,000 so that the product of these two numbers did not overflow a
60        32-bit integer. However, it turns out that people want to use groups that
61        are longer than 30,000 bytes (though not repeat them that many times).
62        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
63        made it possible to implement the integer overflow checks in a much more
64        dynamic way, which I have now done. The artificial limitation on group
65        length has been removed - we now have only the limit on the total length of
66        the compiled pattern, which depends on the LINK_SIZE setting.
68    10. Fixed a bug in the documentation for get/copy named substring when
69        duplicate names are permitted. If none of the named substrings are set, the
70        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
71        empty string.
73    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
74        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
75        because the ] is interpreted as the first data character and the
76        terminating ] is not found. PCRE has been made compatible with Perl in this
77        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
78        cause memory overwriting.
80    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
81        string has been matched (to stop an infinite loop). It was not recognizing
82        a conditional subpattern that could match an empty string if that
83        subpattern was within another subpattern. For example, it looped when
84        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
85        condition was not nested. This bug has been fixed.
87    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
88        past the start of the subject in the presence of bytes with the top bit
89        set, for example "\x8aBCD".
91    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
92        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
94    14. Optimized (?!) to (*FAIL).
96    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
97        This restricts code points to be within the range 0 to 0x10FFFF, excluding
98        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
99        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
100        does: it's just the validity check that is more restrictive.
102    16. Inserted checks for integer overflows during escape sequence (backslash)
103        processing, and also fixed erroneous offset values for syntax errors during
104        backslash processing.
106    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
107        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
110    Version 7.2 19-Jun-07
111    ---------------------
113     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
114        which is apparently normally available under Windows.
116     2. Re-jig the pcregrep tests with different newline settings in an attempt
117        to make them independent of the local environment's newline setting.
119     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
121     4. Some of the "internals" tests were previously cut out when the link size
122        was not 2, because the output contained actual offsets. The recent new
123        "Z" feature of pcretest means that these can be cut out, making the tests
124        usable with all link sizes.
126     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
127        stack recursion. This gives a massive performance boost under BSD, but just
128        a small improvement under Linux. However, it saves one field in the frame
129        in all cases.
131     6. Added more features from the forthcoming Perl 5.10:
133        (a) (?-n) (where n is a string of digits) is a relative subroutine or
134            recursion call. It refers to the nth most recently opened parentheses.
136        (b) (?+n) is also a relative subroutine call; it refers to the nth next
137            to be opened parentheses.
139        (c) Conditions that refer to capturing parentheses can be specified
140            relatively, for example, (?(-2)... or (?(+3)...
142        (d) \K resets the start of the current match so that everything before
143            is not part of it.
145        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
147        (f) \g{name} is another synonym - part of Perl 5.10's unification of
148            reference syntax.
150        (g) (?| introduces a group in which the numbering of parentheses in each
151            alternative starts with the same number.
153        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
155     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
158     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
159        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
160        for detecting groups that can match an empty string.
162     9. A pattern with a very large number of alternatives (more than several
163        hundred) was running out of internal workspace during the pre-compile
164        phase, where pcre_compile() figures out how much memory will be needed. A
165        bit of new cunning has reduced the workspace needed for groups with
166        alternatives. The 1000-alternative test pattern now uses 12 bytes of
167        workspace instead of running out of the 4096 that are available.
169    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
171    11. Applied patch from Google to remove an optimization that didn't quite work.
172        The report of the bug said:
174          pcrecpp::RE("a*").FullMatch("aaa") matches, while
175          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
176          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
178    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
179        it matched the wrong number of bytes.
182    Version 7.1 24-Apr-07
183    ---------------------
185     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
186        that is more "standard", making use of automake and other Autotools. There
187        is some re-arrangement of the files and adjustment of comments consequent
188        on this.
190     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
191        for recursive directory scanning broke on some systems because the files
192        are not scanned in any specific order and on different systems the order
193        was different. A call to "sort" has been inserted into RunGrepTest for the
194        approprate test as a short-term fix. In the longer term there may be an
195        alternative.
197     3. I had an email from Eric Raymond about problems translating some of PCRE's
198        man pages to HTML (despite the fact that I distribute HTML pages, some
199        people do their own conversions for various reasons). The problems
200        concerned the use of low-level troff macros .br and .in. I have therefore
201        removed all such uses from the man pages (some were redundant, some could
202        be replaced by .nf/.fi pairs). The 132html script that I use to generate
203        HTML has been updated to handle .nf/.fi and to complain if it encounters
204        .br or .in.
206     4. Updated comments in configure.ac that get placed in config.h.in and also
207        arranged for config.h to be included in the distribution, with the name
208        config.h.generic, for the benefit of those who have to compile without
209        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
211     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
212        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
213        makevp.bat for the current PCRE, using the additional files
214        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
216     6. A Windows user reported a minor discrepancy with test 2, which turned out
217        to be caused by a trailing space on an input line that had got lost in his
218        copy. The trailing space was an accident, so I've just removed it.
220     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
221        that is needed.
223     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
224        as "const" (a) because they are and (b) because it helps the PHP
225        maintainers who have recently made a script to detect big data structures
226        in the php code that should be moved to the .rodata section. I remembered
227        to update Builducptable as well, so it won't revert if ucptable.h is ever
228        re-created.
230     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
231        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
232        order to be able to cut out the UTF-8 tables in the latter when UTF-8
233        support is not required. This saves 1.5-2K of code, which is important in
234        some applications.
236        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
237        so as not to refer to the tables, even though these functions will never be
238        called when UTF-8 support is disabled. Otherwise there are problems with a
239        shared library.
241    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
243        (a) It was defining its arguments as char * instead of void *.
245        (b) It was assuming that all moves were upwards in memory; this was true
246            a long time ago when I wrote it, but is no longer the case.
248        The emulated memove() is provided for those environments that have neither
249        memmove() nor bcopy(). I didn't think anyone used it these days, but that
250        is clearly not the case, as these two bugs were recently reported.
252    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
253        and Detrail to create the HTML documentation, the .txt form of the man
254        pages, and it removes trailing spaces from listed files. It also creates
255        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
256        case, it wraps all the #defines with #ifndefs. This script should be run
257        before "make dist".
259    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
260        with Unicode property support.
262        (a) For a maximizing quantifier, if the two different cases of the
263            character were of different lengths in their UTF-8 codings (there are
264            some cases like this - I found 11), and the matching function had to
265            back up over a mixture of the two cases, it incorrectly assumed they
266            were both the same length.
268        (b) When PCRE was configured to use the heap rather than the stack for
269            recursion during matching, it was not correctly preserving the data for
270            the other case of a UTF-8 character when checking ahead for a match
271            while processing a minimizing repeat. If the check also involved
272            matching a wide character, but failed, corruption could cause an
273            erroneous result when trying to check for a repeat of the original
274            character.
276    13. Some tidying changes to the testing mechanism:
278        (a) The RunTest script now detects the internal link size and whether there
279            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
280            values substituted by "configure". (The RunGrepTest script already did
281            this for UTF-8.) The configure.ac script no longer substitutes the
282            relevant variables.
284        (b) The debugging options /B and /D in pcretest show the compiled bytecode
285            with length and offset values. This means that the output is different
286            for different internal link sizes. Test 2 is skipped for link sizes
287            other than 2 because of this, bypassing the problem. Unfortunately,
288            there was also a test in test 3 (the locale tests) that used /B and
289            failed for link sizes other than 2. Rather than cut the whole test out,
290            I have added a new /Z option to pcretest that replaces the length and
291            offset values with spaces. This is now used to make test 3 independent
292            of link size. (Test 2 will be tidied up later.)
294    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
295        segmentation fault instead of returning the appropriate error message.
297    15. In multiline mode when the newline sequence was set to "any", the pattern
298        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
299        This doesn't seem right; it now treats the CRLF combination as the line
300        ending, and so does not match in that case. It's only a pattern such as ^$
301        that would hit this one: something like ^ABC$ would have failed after \r
302        and then tried again after \r\n.
304    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
305        in an attempt to make files that differ only in their line terminators
306        compare equal. This works on Linux.
308    17. Under certain error circumstances pcregrep might try to free random memory
309        as it exited. This is now fixed, thanks to valgrind.
311    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
312        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
313        was because its rules for how to advance for /g after matching an empty
314        string at the end of a line did not allow for this case. They now check for
315        it specially.
317    20. pcretest is supposed to handle patterns and data of any length, by
318        extending its buffers when necessary. It was getting this wrong when the
319        buffer for a data line had to be extended.
321    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
322        CRLF as a newline sequence.
324    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
325        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
326        I have nevertheless tidied it up.
328    23. Added some casts to kill warnings from HP-UX ia64 compiler.
330    24. Added a man page for pcre-config.
333    Version 7.0 19-Dec-06
334    ---------------------
336     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
337        moving to gcc 4.1.1.
339     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
340        sys/time.h, which is documented as needed for this function. It doesn't
341        seem to matter on Linux, but it showed up on some releases of OS X.
343     3. It seems that there are systems where bytes whose values are greater than
344        127 match isprint() in the "C" locale. The "C" locale should be the
345        default when a C program starts up. In most systems, only ASCII printing
346        characters match isprint(). This difference caused the output from pcretest
347        to vary, making some of the tests fail. I have changed pcretest so that:
349        (a) When it is outputting text in the compiled version of a pattern, bytes
350            other than 32-126 are always shown as hex escapes.
352        (b) When it is outputting text that is a matched part of a subject string,
353            it does the same, unless a different locale has been set for the match
354            (using the /L modifier). In this case, it uses isprint() to decide.
356     4. Fixed a major bug that caused incorrect computation of the amount of memory
357        required for a compiled pattern when options that changed within the
358        pattern affected the logic of the preliminary scan that determines the
359        length. The relevant options are -x, and -i in UTF-8 mode. The result was
360        that the computed length was too small. The symptoms of this bug were
361        either the PCRE error "internal error: code overflow" from pcre_compile(),
362        or a glibc crash with a message such as "pcretest: free(): invalid next
363        size (fast)". Examples of patterns that provoked this bug (shown in
364        pcretest format) are:
366          /(?-x: )/x
367          /(?x)(?-x: \s*#\s*)/
368          /((?i)[\x{c0}])/8
369          /(?i:[\x{c0}])/8
371        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
372        is now done differently.
374     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
375        wrapper classes; (b) implement a new function in the C++ scanner that is
376        more efficient than the old way of doing things because it avoids levels of
377        recursion in the regex matching; (c) add a paragraph to the documentation
378        for the FullMatch() function.
380     6. The escape sequence \n was being treated as whatever was defined as
381        "newline". Not only was this contrary to the documentation, which states
382        that \n is character 10 (hex 0A), but it also went horribly wrong when
383        "newline" was defined as CRLF. This has been fixed.
385     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
386        was being set to -1 for the "end of line" case (supposedly a value that no
387        character can have). Though this value is never used (the check for end of
388        line is "zero bytes in current character"), it caused compiler complaints.
389        I've changed it to 0xffffffff.
391     8. In pcre_version.c, the version string was being built by a sequence of
392        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
393        string (as it is for production releases) called a macro with an empty
394        argument. The C standard says the result of this is undefined. The gcc
395        compiler treats it as an empty string (which was what was wanted) but it is
396        reported that Visual C gives an error. The source has been hacked around to
397        avoid this problem.
399     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
400        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
401        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
402        of them did).
404    10. Originally, pcretest opened its input and output without "b"; then I was
405        told that "b" was needed in some environments, so it was added for release
406        5.0 to both the input and output. (It makes no difference on Unix-like
407        systems.) Later I was told that it is wrong for the input on Windows. I've
408        now abstracted the modes into two macros, to make it easier to fiddle with
409        them, and removed "b" from the input mode under Windows.
411    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
413    12. Added -help and --help to pcretest as an official way of being reminded
414        of the options.
416    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
417        and pcrecpp.cc because they annoy compilers at high warning levels.
419    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
421    15. Fixed an occurrence of == in configure.ac that should have been = (shell
422        scripts are not C programs :-) and which was not noticed because it works
423        on Linux.
425    16. pcretest is supposed to handle any length of pattern and data line (as one
426        line or as a continued sequence of lines) by extending its input buffer if
427        necessary. This feature was broken for very long pattern lines, leading to
428        a string of junk being passed to pcre_compile() if the pattern was longer
429        than about 50K.
431    17. I have done a major re-factoring of the way pcre_compile() computes the
432        amount of memory needed for a compiled pattern. Previously, there was code
433        that made a preliminary scan of the pattern in order to do this. That was
434        OK when PCRE was new, but as the facilities have expanded, it has become
435        harder and harder to keep it in step with the real compile phase, and there
436        have been a number of bugs (see for example, 4 above). I have now found a
437        cunning way of running the real compile function in a "fake" mode that
438        enables it to compute how much memory it would need, while actually only
439        ever using a few hundred bytes of working memory and without too many
440        tests of the mode. This should make future maintenance and development
441        easier. A side effect of this work is that the limit of 200 on the nesting
442        depth of parentheses has been removed (though this was never a serious
443        limitation, I suspect). However, there is a downside: pcre_compile() now
444        runs more slowly than before (30% or more, depending on the pattern). I
445        hope this isn't a big issue. There is no effect on runtime performance.
447    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
448        newline (only possible for the last line of a file) and it was a
449        pattern that set a locale (followed by /Lsomething), pcretest crashed.
451    19. Added additional timing features to pcretest. (1) The -tm option now times
452        matching only, not compiling. (2) Both -t and -tm can be followed, as a
453        separate command line item, by a number that specifies the number of
454        repeats to use when timing. The default is 50000; this gives better
455        precision, but takes uncomfortably long for very large patterns.
457    20. Extended pcre_study() to be more clever in cases where a branch of a
458        subpattern has no definite first character. For example, (a*|b*)[cd] would
459        previously give no result from pcre_study(). Now it recognizes that the
460        first character must be a, b, c, or d.
462    21. There was an incorrect error "recursive call could loop indefinitely" if
463        a subpattern (or the entire pattern) that was being tested for matching an
464        empty string contained only one non-empty item after a nested subpattern.
465        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
466        incorrectly, because the \d was being skipped in the check.
468    22. The pcretest program now has a new pattern option /B and a command line
469        option -b, which is equivalent to adding /B to every pattern. This causes
470        it to show the compiled bytecode, without the additional information that
471        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
472        is the same as /B/I).
474    23. A new optimization is now able automatically to treat some sequences such
475        as a*b as a*+b. More specifically, if something simple (such as a character
476        or a simple class like \d) has an unlimited quantifier, and is followed by
477        something that cannot possibly match the quantified thing, the quantifier
478        is automatically "possessified".
480    24. A recursive reference to a subpattern whose number was greater than 39
481        went wrong under certain circumstances in UTF-8 mode. This bug could also
482        have affected the operation of pcre_study().
484    25. Realized that a little bit of performance could be had by replacing
485        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
487    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
489    27. Possessive quantifiers such as a++ were previously implemented by turning
490        them into atomic groups such as ($>a+). Now they have their own opcodes,
491        which improves performance. This includes the automatically created ones
492        from 23 above.
494    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
495        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
496        the first matched character to be a colon. This applied both to named and
497        numbered groups.
499    29. The ucpinternal.h header file was missing its idempotency #ifdef.
501    30. I was sent a "project" file called libpcre.a.dev which I understand makes
502        building PCRE on Windows easier, so I have included it in the distribution.
504    31. There is now a check in pcretest against a ridiculously large number being
505        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
506        loop, the loop is abandoned.
508    32. Forward references to subpatterns in conditions such as (?(2)...) where
509        subpattern 2 is defined later cause pcre_compile() to search forwards in
510        the pattern for the relevant set of parentheses. This search went wrong
511        when there were unescaped parentheses in a character class, parentheses
512        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
514    33. "Subroutine" calls and backreferences were previously restricted to
515        referencing subpatterns earlier in the regex. This restriction has now
516        been removed.
518    34. Added a number of extra features that are going to be in Perl 5.10. On the
519        whole, these are just syntactic alternatives for features that PCRE had
520        previously implemented using the Python syntax or my own invention. The
521        other formats are all retained for compatibility.
523        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
524            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
525            also .NET compatible.
527        (b) A recursion or subroutine call to a named group can now be defined as
528            (?&name) as well as (?P>name).
530        (c) A backreference to a named group can now be defined as \k<name> or
531            \k'name' as well as (?P=name). The new forms, as well as being in Perl
532            5.10, are also .NET compatible.
534        (d) A conditional reference to a named group can now use the syntax
535            (?(<name>) or (?('name') as well as (?(name).
537        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
538            groups (named and numbered) that are never evaluated inline, but can be
539            called as "subroutines" from elsewhere. In effect, the DEFINE condition
540            is always false. There may be only one alternative in such a group.
542        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
543            as the simple (?(R). The condition is true only if the most recent
544            recursion is that of the given number or name. It does not search out
545            through the entire recursion stack.
547        (g) The escape \gN or \g{N} has been added, where N is a positive or
548            negative number, specifying an absolute or relative reference.
550    35. Tidied to get rid of some further signed/unsigned compiler warnings and
551        some "unreachable code" warnings.
553    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
554        things, this adds five new scripts.
556    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
557        There were also incompatibilities regarding the handling of \Q..\E inside
558        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
559        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
561    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
562        matches an empty string, and forcibly breaks the loop. There were bugs in
563        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
564        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
565        separate and independent bugs (that affected different cases) have been
566        fixed.
568    39. Refactored the code to abolish the use of different opcodes for small
569        capturing bracket numbers. This is a tidy that I avoided doing when I
570        removed the limit on the number of capturing brackets for 3.5 back in 2001.
571        The new approach is not only tidier, it makes it possible to reduce the
572        memory needed to fix the previous bug (38).
574    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
575        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
576        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
577        mode.
579    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
580        report.
582    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
583        copy construction and assignment in the C++ wrapper.
585    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
586        couple of bugs that could have given wrong results in the "--newline=crlf"
587        case.
589    44. Added a number of casts and did some reorganization of signed/unsigned int
590        variables following suggestions from Dair Grant. Also renamed the variable
591        "this" as "item" because it is a C++ keyword.
593    45. Arranged for dftables to add
595          #include "pcre_internal.h"
597        to pcre_chartables.c because without it, gcc 4.x may remove the array
598        definition from the final binary if PCRE is built into a static library and
599        dead code stripping is activated.
601    46. For an unanchored pattern, if a match attempt fails at the start of a
602        newline sequence, and the newline setting is CRLF or ANY, and the next two
603        characters are CRLF, advance by two characters instead of one.
606    Version 6.7 04-Jul-06
607    ---------------------
609     1. In order to handle tests when input lines are enormously long, pcretest has
610        been re-factored so that it automatically extends its buffers when
611        necessary. The code is crude, but this _is_ just a test program. The
612        default size has been increased from 32K to 50K.
614     2. The code in pcre_study() was using the value of the re argument before
615        testing it for NULL. (Of course, in any sensible call of the function, it
616        won't be NULL.)
618     3. The memmove() emulation function in pcre_internal.h, which is used on
619        systems that lack both memmove() and bcopy() - that is, hardly ever -
620        was missing a "static" storage class specifier.
622     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
623        containing an extended class (one that cannot be represented by a bitmap
624        because it contains high-valued characters or Unicode property items, e.g.
625        [\pZ]). Almost always one would set UTF-8 mode when processing such a
626        pattern, but PCRE should not loop if you do not (it no longer does).
627        [Detail: two cases were found: (a) a repeated subpattern containing an
628        extended class; (b) a recursive reference to a subpattern that followed a
629        previous extended class. It wasn't skipping over the extended class
630        correctly when UTF-8 mode was not set.]
632     5. A negated single-character class was not being recognized as fixed-length
633        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
634        compile error "lookbehind assertion is not fixed length".
636     6. The RunPerlTest auxiliary script was showing an unexpected difference
637        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
638        write a Perl script that can interpret lines of an input file either as
639        byte characters or as UTF-8, which is what "perltest" was being required to
640        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
641        can't do is switch easily at run time between having the "use utf8;" pragma
642        or not. In the end, I fudged it by using the RunPerlTest script to insert
643        "use utf8;" explicitly for the UTF-8 tests.
645     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
646        the end of the subject string, contrary to the documentation and to what
647        Perl does. This was true of both matching functions. Now it matches only at
648        the start of the subject and immediately after *internal* newlines.
650     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
651        a pointer to an int instead of a pointer to an unsigned long int. This
652        caused problems on 64-bit systems.
654     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
655        instance of the 'standard' template library not being so standard".
657    10. There was no check on the number of named subpatterns nor the maximum
658        length of a subpattern name. The product of these values is used to compute
659        the size of the memory block for a compiled pattern. By supplying a very
660        long subpattern name and a large number of named subpatterns, the size
661        computation could be caused to overflow. This is now prevented by limiting
662        the length of names to 32 characters, and the number of named subpatterns
663        to 10,000.
665    11. Subpatterns that are repeated with specific counts have to be replicated in
666        the compiled pattern. The size of memory for this was computed from the
667        length of the subpattern and the repeat count. The latter is limited to
668        65535, but there was no limit on the former, meaning that integer overflow
669        could in principle occur. The compiled length of a repeated subpattern is
670        now limited to 30,000 bytes in order to prevent this.
672    12. Added the optional facility to have named substrings with the same name.
674    13. Added the ability to use a named substring as a condition, using the
675        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
676        are numbers (not recommended). Forward references are permitted.
678    14. Added forward references in named backreferences (if you see what I mean).
680    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
681        pattern could run off the end of the subject. For example, the pattern
682        "(?s)(.{1,5})"8 did this with the subject "ab".
684    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
685        PCRE_CASELESS was set when matching characters that were quantified with ?
686        or *.
688    17. A character class other than a single negated character that had a minimum
689        but no maximum quantifier - for example [ab]{6,} - was not handled
690        correctly by pce_dfa_exec(). It would match only one character.
692    18. A valid (though odd) pattern that looked like a POSIX character
693        class but used an invalid character after [ (for example [[,abc,]]) caused
694        pcre_compile() to give the error "Failed: internal error: code overflow" or
695        in some cases to crash with a glibc free() error. This could even happen if
696        the pattern terminated after [[ but there just happened to be a sequence of
697        letters, a binary zero, and a closing ] in the memory that followed.
699    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
700        over the years. Originally (before any Unicode support), just the bottom 8
701        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
702        output from "man perlunicode" includes this:
704          The regular expression compiler produces polymorphic opcodes.  That
705          is, the pattern adapts to the data and automatically switches to
706          the Unicode character scheme when presented with Unicode data--or
707          instead uses a traditional byte scheme when presented with byte
708          data.
710        Sadly, a wide octal escape does not cause a switch, and in a string with
711        no other multibyte characters, these octal escapes are treated as before.
712        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
713        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
714        Unicode string.
716        I have not perpetrated such confusion in PCRE. Up till now, it took just
717        the bottom 8 bits, as in old Perl. I have now made octal escapes with
718        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
719        translate to the appropriate multibyte character.
721    29. Applied some refactoring to reduce the number of warnings from Microsoft
722        and Borland compilers. This has included removing the fudge introduced
723        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
724        a warning about an unused variable.
726    21. PCRE has not included VT (character 0x0b) in the set of whitespace
727        characters since release 4.0, because Perl (from release 5.004) does not.
728        [Or at least, is documented not to: some releases seem to be in conflict
729        with the documentation.] However, when a pattern was studied with
730        pcre_study() and all its branches started with \s, PCRE still included VT
731        as a possible starting character. Of course, this did no harm; it just
732        caused an unnecessary match attempt.
734    22. Removed a now-redundant internal flag bit that recorded the fact that case
735        dependency changed within the pattern. This was once needed for "required
736        byte" processing, but is no longer used. This recovers a now-scarce options
737        bit. Also moved the least significant internal flag bit to the most-
738        significant bit of the word, which was not previously used (hangover from
739        the days when it was an int rather than a uint) to free up another bit for
740        the future.
742    23. Added support for CRLF line endings as well as CR and LF. As well as the
743        default being selectable at build time, it can now be changed at runtime
744        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
745        specify that it is scanning data with non-default line endings.
747    24. Changed the definition of CXXLINK to make it agree with the definition of
748        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
750    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
751        recursions. This makes a big different to stack usage for some patterns.
753    26. If a subpattern containing a named recursion or subroutine reference such
754        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
755        the space required for the compiled pattern went wrong and gave too small a
756        value. Depending on the environment, this could lead to "Failed: internal
757        error: code overflow at offset 49" or "glibc detected double free or
758        corruption" errors.
760    27. Applied patches from Google (a) to support the new newline modes and (b) to
761        advance over multibyte UTF-8 characters in GlobalReplace.
763    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
764        difference for some implementation of PCRE in some Windows version.
766    29. Added some extra testing facilities to pcretest:
768        \q<number>   in a data line sets the "match limit" value
769        \Q<number>   in a data line sets the "match recursion limt" value
770        -S <number>  sets the stack size, where <number> is in megabytes
772        The -S option isn't available for Windows.
775    Version 6.6 06-Feb-06
776    ---------------------
778     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
779        in pcreposix.h. I have copied the definition from pcre.h.
781     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
782        because pcre.h is no longer a built file.
784     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
785        not normally included in the compiled code.
788    Version 6.5 01-Feb-06
789    ---------------------
791     1. When using the partial match feature with pcre_dfa_exec(), it was not
792        anchoring the second and subsequent partial matches at the new starting
793        point. This could lead to incorrect results. For example, with the pattern
794        /1234/, partially matching against "123" and then "a4" gave a match.
796     2. Changes to pcregrep:
798        (a) All non-match returns from pcre_exec() were being treated as failures
799            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
800            error message is output. Some extra information is given for the
801            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
802            probably the only errors that are likely to be caused by users (by
803            specifying a regex that has nested indefinite repeats, for instance).
804            If there are more than 20 of these errors, pcregrep is abandoned.
806        (b) A binary zero was treated as data while matching, but terminated the
807            output line if it was written out. This has been fixed: binary zeroes
808            are now no different to any other data bytes.
810        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
811            used to set a locale for matching. The --locale=xxxx long option has
812            been added (no short equivalent) to specify a locale explicitly on the
813            pcregrep command, overriding the environment variables.
815        (d) When -B was used with -n, some line numbers in the output were one less
816            than they should have been.
818        (e) Added the -o (--only-matching) option.
820        (f) If -A or -C was used with -c (count only), some lines of context were
821            accidentally printed for the final match.
823        (g) Added the -H (--with-filename) option.
825        (h) The combination of options -rh failed to suppress file names for files
826            that were found from directory arguments.
828        (i) Added the -D (--devices) and -d (--directories) options.
830        (j) Added the -F (--fixed-strings) option.
832        (k) Allow "-" to be used as a file name for -f as well as for a data file.
834        (l) Added the --colo(u)r option.
836        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
837            is not present by default.
839     3. A nasty bug was discovered in the handling of recursive patterns, that is,
840        items such as (?R) or (?1), when the recursion could match a number of
841        alternatives. If it matched one of the alternatives, but subsequently,
842        outside the recursion, there was a failure, the code tried to back up into
843        the recursion. However, because of the way PCRE is implemented, this is not
844        possible, and the result was an incorrect result from the match.
846        In order to prevent this happening, the specification of recursion has
847        been changed so that all such subpatterns are automatically treated as
848        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
850     4. I had overlooked the fact that, in some locales, there are characters for
851        which isalpha() is true but neither isupper() nor islower() are true. In
852        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
853        and ordfeminine) are like this. This affected the treatment of \w and \W
854        when they appeared in character classes, but not when they appeared outside
855        a character class. The bit map for "word" characters is now created
856        separately from the results of isalnum() instead of just taking it from the
857        upper, lower, and digit maps. (Plus the underscore character, of course.)
859     5. The above bug also affected the handling of POSIX character classes such as
860        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
861        permanent tables. Instead, the bit maps for such a class were previously
862        created as the appropriate unions of the upper, lower, and digit bitmaps.
863        Now they are created by subtraction from the [[:word:]] class, which has
864        its own bitmap.
866     6. The [[:blank:]] character class matches horizontal, but not vertical space.
867        It is created by subtracting the vertical space characters (\x09, \x0a,
868        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
869        subtraction was done in the overall bitmap for a character class, meaning
870        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
871        be recognized. This bug has been fixed.
873     7. Patches from the folks at Google:
875          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
876          real life, but is still worth protecting against".
878          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
879          regular expressions".
881          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
882          have it.
884          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
885          "configure" and the latter not, in order to fix a problem somebody had
886          with compiling the Arg class on HP-UX.
888          (e) Improve the error-handling of the C++ wrapper a little bit.
890          (f) New tests for checking recursion limiting.
892     8. The pcre_memmove() function, which is used only if the environment does not
893        have a standard memmove() function (and is therefore rarely compiled),
894        contained two bugs: (a) use of int instead of size_t, and (b) it was not
895        returning a result (though PCRE never actually uses the result).
897     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
898        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
899        returned instead of calling malloc() with an overflowing number that would
900        most likely cause subsequent chaos.
902    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
904    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
905        with this option is matched, the nmatch and pmatch options of regexec() are
906        ignored.
908    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
909        provided in case anyone wants to the the POSIX interface with UTF-8
910        strings.
912    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
913        C++ linking (needed for some HP-UX environments).
915    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
916        (unused parameter) and in the pcre_printint() function (omitted "default"
917        switch label when the default is to do nothing).
919    15. Added some code to make it possible, when PCRE is compiled as a C++
920        library, to replace subject pointers for pcre_exec() with a smart pointer
921        class, thus making it possible to process discontinuous strings.
923    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
924        much the same function. They were added by different people who were trying
925        to make PCRE easy to compile on non-Unix systems. It has been suggested
926        that PCRE_EXPORT be abolished now that there is more automatic apparatus
927        for compiling on Windows systems. I have therefore replaced it with
928        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
929        defaults to "extern" for C or "extern C" for C++, which works fine on
930        Unix-like systems. It is now possible to override the value of PCRE_DATA_
931        SCOPE with something explicit in config.h. In addition:
933        (a) pcreposix.h still had just "extern" instead of either of these macros;
934            I have replaced it with PCRE_DATA_SCOPE.
936        (b) Functions such as _pcre_xclass(), which are internal to the library,
937            but external in the C sense, all had PCRE_EXPORT in their definitions.
938            This is apparently wrong for the Windows case, so I have removed it.
939            (It makes no difference on Unix-like systems.)
941    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
942        of recursive calls to match(). This is different to MATCH_LIMIT because
943        that limits the total number of calls to match(), not all of which increase
944        the depth of recursion. Limiting the recursion depth limits the amount of
945        stack (or heap if NO_RECURSE is set) that is used. The default can be set
946        when PCRE is compiled, and changed at run time. A patch from Google adds
947        this functionality to the C++ interface.
949    18. Changes to the handling of Unicode character properties:
951        (a) Updated the table to Unicode 4.1.0.
953        (b) Recognize characters that are not in the table as "Cn" (undefined).
955        (c) I revised the way the table is implemented to a much improved format
956            which includes recognition of ranges. It now supports the ranges that
957            are defined in UnicodeData.txt, and it also amalgamates other
958            characters into ranges. This has reduced the number of entries in the
959            table from around 16,000 to around 3,000, thus reducing its size
960            considerably. I realized I did not need to use a tree structure after
961            all - a binary chop search is just as efficient. Having reduced the
962            number of entries, I extended their size from 6 bytes to 8 bytes to
963            allow for more data.
965        (d) Added support for Unicode script names via properties such as \p{Han}.
967    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
968        matching that character.
970    20. When matching a repeated Unicode property with a minimum greater than zero,
971        (for example \pL{2,}), PCRE could look past the end of the subject if it
972        reached it while seeking the minimum number of characters. This could
973        happen only if some of the characters were more than one byte long, because
974        there is a check for at least the minimum number of bytes.
976    21. Refactored the implementation of \p and \P so as to be more general, to
977        allow for more different types of property in future. This has changed the
978        compiled form incompatibly. Anybody with saved compiled patterns that use
979        \p or \P will have to recompile them.
981    22. Added "Any" and "L&" to the supported property types.
983    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
984        but give a compile time error if the value is greater than 0xff.
986    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
987        accidentally not being installed or uninstalled.
989    25. The pcre.h file was built from pcre.h.in, but the only changes that were
990        made were to insert the current release number. This seemed silly, because
991        it made things harder for people building PCRE on systems that don't run
992        "configure". I have turned pcre.h into a distributed file, no longer built
993        by "configure", with the version identification directly included. There is
994        no longer a pcre.h.in file.
996        However, this change necessitated a change to the pcre-config script as
997        well. It is built from pcre-config.in, and one of the substitutions was the
998        release number. I have updated configure.ac so that ./configure now finds
999        the release number by grepping pcre.h.
1001    26. Added the ability to run the tests under valgrind.
1004    Version 6.4 05-Sep-05
1005    ---------------------
1007     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1008        "--" to be printed when multiple files were scanned, even when none of the
1009        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1010        consider it to be a bug, and have restored the previous behaviour.
1012     2. A couple of code tidies to get rid of compiler warnings.
1014     3. The pcretest program used to cheat by referring to symbols in the library
1015        whose names begin with _pcre_. These are internal symbols that are not
1016        really supposed to be visible externally, and in some environments it is
1017        possible to suppress them. The cheating is now confined to including
1018        certain files from the library's source, which is a bit cleaner.
1020     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1021        file's purpose clearer.
1023     5. Reorganized pcre_ucp_findchar().
1026    Version 6.3 15-Aug-05
1027    ---------------------
1029     1. The file libpcre.pc.in did not have general read permission in the tarball.
1031     2. There were some problems when building without C++ support:
1033        (a) If C++ support was not built, "make install" and "make test" still
1034            tried to test it.
1036        (b) There were problems when the value of CXX was explicitly set. Some
1037            changes have been made to try to fix these, and ...
1039        (c) --disable-cpp can now be used to explicitly disable C++ support.
1041        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1042            backslash in a target when C++ was disabled. This confuses some
1043            versions of "make", apparently. Using an intermediate variable solves
1044            this. (Same for CPP_LOBJ.)
1046     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1047        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1048        necessary on certain architectures.
1050     4. Added a setting of -export-symbols-regex to the link command to remove
1051        those symbols that are exported in the C sense, but actually are local
1052        within the library, and not documented. Their names all begin with
1053        "_pcre_". This is not a perfect job, because (a) we have to except some
1054        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1055        available (and never for static libraries). I have made a note to try to
1056        find a way round (a) in the future.
1059    Version 6.2 01-Aug-05
1060    ---------------------
1062     1. There was no test for integer overflow of quantifier values. A construction
1063        such as {1111111111111111} would give undefined results. What is worse, if
1064        a minimum quantifier for a parenthesized subpattern overflowed and became
1065        negative, the calculation of the memory size went wrong. This could have
1066        led to memory overwriting.
1068     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1070     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1071        operating environments where this matters.
1073     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1074        PCRE options from within the C++ wrapper.
1076     5. Named capturing subpatterns were not being correctly counted when a pattern
1077        was compiled. This caused two problems: (a) If there were more than 100
1078        such subpatterns, the calculation of the memory needed for the whole
1079        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1080        back references of the form \12, where the number was greater than 9, were
1081        not recognized as back references, even though there were sufficient
1082        previous subpatterns.
1084     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1085        versions of gcc, e.g. 2.95.4.
1088    Version 6.1 21-Jun-05
1089    ---------------------
1091     1. There was one reference to the variable "posix" in pcretest.c that was not
1092        surrounded by "#if !defined NOPOSIX".
1094     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1095        the cross-check on the old pcre_info() function, for the benefit of the
1096        cut-down version of PCRE that is currently imported into Exim.
1098     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1099        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1100        patterns that start (?i) but I don't think that matters. The use of (?i) is
1101        just an example; this all applies to the other options as well.
1103     4. Since libtool seems to echo the compile commands it is issuing, the output
1104        from "make" can be reduced a bit by putting "@" in front of each libtool
1105        compile command.
1107     5. Patch from the folks at Google for configure.in to be a bit more thorough
1108        in checking for a suitable C++ installation before trying to compile the
1109        C++ stuff. This should fix a reported problem when a compiler was present,
1110        but no suitable headers.
1112     6. The man pages all had just "PCRE" as their title. I have changed them to
1113        be the relevant file name. I have also arranged that these names are
1114        retained in the file doc/pcre.txt, which is a concatenation in text format
1115        of all the man pages except the little individual ones for each function.
1117     7. The NON-UNIX-USE file had not been updated for the different set of source
1118        files that come with release 6. I also added a few comments about the C++
1119        wrapper.
1122    Version 6.0 07-Jun-05
1123    ---------------------
1125     1. Some minor internal re-organization to help with my DFA experiments.
1127     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1128        didn't matter for the library itself when fully configured, but did matter
1129        when compiling without UCP support, or within Exim, where the ucp files are
1130        not imported.
1132     3. Refactoring of the library code to split up the various functions into
1133        different source modules. The addition of the new DFA matching code (see
1134        below) to a single monolithic source would have made it really too
1135        unwieldy, quite apart from causing all the code to be include in a
1136        statically linked application, when only some functions are used. This is
1137        relevant even without the DFA addition now that patterns can be compiled in
1138        one application and matched in another.
1140        The downside of splitting up is that there have to be some external
1141        functions and data tables that are used internally in different modules of
1142        the library but which are not part of the API. These have all had their
1143        names changed to start with "_pcre_" so that they are unlikely to clash
1144        with other external names.
1146     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1147        a different (DFA) algorithm. Although it is slower than the original
1148        function, it does have some advantages for certain types of matching
1149        problem.
1151     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1152        including restarting after a partial match.
1154     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1155        defined when compiling for Windows was sent to me. I have put it into the
1156        code, though I have no means of testing or verifying it.
1158     7. Added the pcre_refcount() auxiliary function.
1160     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1161        match before or at the first newline in the subject string. In pcretest,
1162        the /f option on a pattern can be used to set this.
1164     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1165        would behave wrongly. This has been present in PCRE since release 4.0.
1167    10. A number of changes to the pcregrep command:
1169        (a) Refactored how -x works; insert ^(...)$ instead of setting
1170            PCRE_ANCHORED and checking the length, in preparation for adding
1171            something similar for -w.
1173        (b) Added the -w (match as a word) option.
1175        (c) Refactored the way lines are read and buffered so as to have more
1176            than one at a time available.
1178        (d) Implemented a pcregrep test script.
1180        (e) Added the -M (multiline match) option. This allows patterns to match
1181            over several lines of the subject. The buffering ensures that at least
1182            8K, or the rest of the document (whichever is the shorter) is available
1183            for matching (and similarly the previous 8K for lookbehind assertions).
1185        (f) Changed the --help output so that it now says
1187              -w, --word-regex(p)
1189            instead of two lines, one with "regex" and the other with "regexp"
1190            because that confused at least one person since the short forms are the
1191            same. (This required a bit of code, as the output is generated
1192            automatically from a table. It wasn't just a text change.)
1194        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1195            option but starts with a hyphen. Could be a pattern or a path name
1196            starting with a hyphen, for instance.
1198        (h) "-" can be given as a file name to represent stdin.
1200        (i) When file names are being printed, "(standard input)" is used for
1201            the standard input, for compatibility with GNU grep. Previously
1202            "<stdin>" was used.
1204        (j) The option --label=xxx can be used to supply a name to be used for
1205            stdin when file names are being printed. There is no short form.
1207        (k) Re-factored the options decoding logic because we are going to add
1208            two more options that take data. Such options can now be given in four
1209            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1211        (l) Added the -A, -B, and -C options for requesting that lines of context
1212            around matches be printed.
1214        (m) Added the -L option to print the names of files that do not contain
1215            any matching lines, that is, the complement of -l.
1217        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1218            continue to scan other files.
1220        (o) The -s option was incorrectly implemented. For compatibility with other
1221            greps, it now suppresses the error message for a non-existent or non-
1222            accessible file (but not the return code). There is a new option called
1223            -q that suppresses the output of matching lines, which was what -s was
1224            previously doing.
1226        (p) Added --include and --exclude options to specify files for inclusion
1227            and exclusion when recursing.
1229    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1230        Hopefully, it now does.
1232    12. Missing cast in pcre_study().
1234    13. Added an "uninstall" target to the makefile.
1236    14. Replaced "extern" in the function prototypes in Makefile.in with
1237        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1238        world, but is set differently for Windows.
1240    15. Added a second compiling function called pcre_compile2(). The only
1241        difference is that it has an extra argument, which is a pointer to an
1242        integer error code. When there is a compile-time failure, this is set
1243        non-zero, in addition to the error test pointer being set to point to an
1244        error message. The new argument may be NULL if no error number is required
1245        (but then you may as well call pcre_compile(), which is now just a
1246        wrapper). This facility is provided because some applications need a
1247        numeric error indication, but it has also enabled me to tidy up the way
1248        compile-time errors are handled in the POSIX wrapper.
1250    16. Added VPATH=.libs to the makefile; this should help when building with one
1251        prefix path and installing with another. (Or so I'm told by someone who
1252        knows more about this stuff than I do.)
1254    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1255        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1256        match everything, including newlines. This is not POSIX-compatible, but
1257        somebody wanted the feature. From pcretest it can be activated by using
1258        both the P and the s flags.
1260    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1262    19. libpcre.pc was being incorrectly installed as executable.
1264    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1265        it now also looks for '\r' so that it will work unmodified on Windows.
1267    21. Added Google's contributed C++ wrapper to the distribution.
1269    22. Added some untidy missing memory free() calls in pcretest, to keep
1270        Electric Fence happy when testing.
1274    Version 5.0 13-Sep-04
1275    ---------------------
1277     1. Internal change: literal characters are no longer packed up into items
1278        containing multiple characters in a single byte-string. Each character
1279        is now matched using a separate opcode. However, there may be more than one
1280        byte in the character in UTF-8 mode.
1282     2. The pcre_callout_block structure has two new fields: pattern_position and
1283        next_item_length. These contain the offset in the pattern to the next match
1284        item, and its length, respectively.
1286     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1287        insertion of callouts before each pattern item. Added the /C option to
1288        pcretest to make use of this.
1290     4. On the advice of a Windows user, the lines
1292          #if defined(_WIN32) || defined(WIN32)
1293          _setmode( _fileno( stdout ), 0x8000 );
1294          #endif  /* defined(_WIN32) || defined(WIN32) */
1296        have been added to the source of pcretest. This apparently does useful
1297        magic in relation to line terminators.
1299     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1300        for the benefit of those environments where the "b" makes a difference.
1302     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1303        to know about it. I have put a hack into configure.in that adds in code
1304        to set GCC=yes if CC=icc. This seems to end up at a point in the
1305        generated configure script that is early enough to affect the setting of
1306        compiler options, which is what is needed, but I have no means of testing
1307        whether it really works. (The user who reported this had patched the
1308        generated configure script, which of course I cannot do.)
1310        LATER: After change 22 below (new libtool files), the configure script
1311        seems to know about icc (and also ecc). Therefore, I have commented out
1312        this hack in configure.in.
1314     7. Added support for pkg-config (2 patches were sent in).
1316     8. Negated POSIX character classes that used a combination of internal tables
1317        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1318        [[:^ascii]]. Typically, they would match almost any characters. The other
1319        POSIX classes were not broken in this way.
1321     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1322        to find the match, as PCRE was deluded into thinking that the match had to
1323        start at the start point or following a newline. The same bug applied to
1324        patterns with negative forward assertions or any backward assertions
1325        preceding ".*" at the start, unless the pattern required a fixed first
1326        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1328    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1329        starting at the last subject character, bytes beyond the end of the subject
1330        string were read.
1332    11. Renamed the variable "class" as "classbits" to make life easier for C++
1333        users. (Previously there was a macro definition, but it apparently wasn't
1334        enough.)
1336    12. Added the new field "tables" to the extra data so that tables can be passed
1337        in at exec time, or the internal tables can be re-selected. This allows
1338        a compiled regex to be saved and re-used at a later time by a different
1339        program that might have everything at different addresses.
1341    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1342        -R library as well as a -L library.
1344    14. The debugging options of pcretest (-d on the command line or D on a
1345        pattern) showed incorrect output for anything following an extended class
1346        that contained multibyte characters and which was followed by a quantifier.
1348    15. Added optional support for general category Unicode character properties
1349        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1350        support. It adds about 90K to the size of the library. The meanings of the
1351        inbuilt class escapes such as \d and \s have NOT been changed.
1353    16. Updated pcredemo.c to include calls to free() to release the memory for the
1354        compiled pattern.
1356    17. The generated file chartables.c was being created in the source directory
1357        instead of in the building directory. This caused the build to fail if the
1358        source directory was different from the building directory, and was
1359        read-only.
1361    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1362        file. No doubt somebody will tell me if they don't make sense... Also added
1363        Dan Mooney's comments about building on OpenVMS.
1365    19. Added support for partial matching via the PCRE_PARTIAL option for
1366        pcre_exec() and the \P data escape in pcretest.
1368    20. Extended pcretest with 3 new pattern features:
1370        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1371              write the compiled pattern to the file whose name is "rest-of-line".
1372              This is a straight binary dump of the data, with the saved pointer to
1373              the character tables forced to be NULL. The study data, if any, is
1374              written too. After writing, pcretest reads a new pattern.
1376        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1377              compiled pattern from the given file. There must not be any
1378              occurrences of "<" in the file name (pretty unlikely); if there are,
1379              pcretest will instead treat the initial "<" as a pattern delimiter.
1380              After reading in the pattern, pcretest goes on to read data lines as
1381              usual.
1383        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1384              and 16-bit fields in a compiled pattern, to simulate a pattern that
1385              was compiled on a host of opposite endianness.
1387    21. The pcre-exec() function can now cope with patterns that were compiled on
1388        hosts of opposite endianness, with this restriction:
1390          As for any compiled expression that is saved and used later, the tables
1391          pointer field cannot be preserved; the extra_data field in the arguments
1392          to pcre_exec() should be used to pass in a tables address if a value
1393          other than the default internal tables were used at compile time.
1395    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1396        now diagnosed as an error. Previously, most of the time, a negative number
1397        would have been treated as zero, but if in addition "ovector" was passed as
1398        NULL, a crash could occur.
1400    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1401        new versions from the libtool 1.5 distribution (the last one is a copy of
1402        a file called libtool.m4). This seems to have fixed the need to patch
1403        "configure" to support Darwin 1.3 (which I used to do). However, I still
1404        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1405        workstation).
1407    24. Changed the PCRE licence to be the more standard "BSD" licence.
1410  Version 4.5 01-Dec-03  Version 4.5 01-Dec-03
1411  ---------------------  ---------------------

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