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revision 15 by nigel, Sat Feb 24 21:38:25 2007 UTC revision 206 by ph10, Fri Aug 3 14:53:04 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.3 05-Jul-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.
88    Version 7.2 19-Jun-07
89    ---------------------
91     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
92        which is apparently normally available under Windows.
94     2. Re-jig the pcregrep tests with different newline settings in an attempt
95        to make them independent of the local environment's newline setting.
97     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
99     4. Some of the "internals" tests were previously cut out when the link size
100        was not 2, because the output contained actual offsets. The recent new
101        "Z" feature of pcretest means that these can be cut out, making the tests
102        usable with all link sizes.
104     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
105        stack recursion. This gives a massive performance boost under BSD, but just
106        a small improvement under Linux. However, it saves one field in the frame
107        in all cases.
109     6. Added more features from the forthcoming Perl 5.10:
111        (a) (?-n) (where n is a string of digits) is a relative subroutine or
112            recursion call. It refers to the nth most recently opened parentheses.
114        (b) (?+n) is also a relative subroutine call; it refers to the nth next
115            to be opened parentheses.
117        (c) Conditions that refer to capturing parentheses can be specified
118            relatively, for example, (?(-2)... or (?(+3)...
120        (d) \K resets the start of the current match so that everything before
121            is not part of it.
123        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
125        (f) \g{name} is another synonym - part of Perl 5.10's unification of
126            reference syntax.
128        (g) (?| introduces a group in which the numbering of parentheses in each
129            alternative starts with the same number.
131        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
133     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
136     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
137        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
138        for detecting groups that can match an empty string.
140     9. A pattern with a very large number of alternatives (more than several
141        hundred) was running out of internal workspace during the pre-compile
142        phase, where pcre_compile() figures out how much memory will be needed. A
143        bit of new cunning has reduced the workspace needed for groups with
144        alternatives. The 1000-alternative test pattern now uses 12 bytes of
145        workspace instead of running out of the 4096 that are available.
147    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
149    11. Applied patch from Google to remove an optimization that didn't quite work.
150        The report of the bug said:
152          pcrecpp::RE("a*").FullMatch("aaa") matches, while
153          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
154          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
156    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
157        it matched the wrong number of bytes.
160    Version 7.1 24-Apr-07
161    ---------------------
163     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
164        that is more "standard", making use of automake and other Autotools. There
165        is some re-arrangement of the files and adjustment of comments consequent
166        on this.
168     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
169        for recursive directory scanning broke on some systems because the files
170        are not scanned in any specific order and on different systems the order
171        was different. A call to "sort" has been inserted into RunGrepTest for the
172        approprate test as a short-term fix. In the longer term there may be an
173        alternative.
175     3. I had an email from Eric Raymond about problems translating some of PCRE's
176        man pages to HTML (despite the fact that I distribute HTML pages, some
177        people do their own conversions for various reasons). The problems
178        concerned the use of low-level troff macros .br and .in. I have therefore
179        removed all such uses from the man pages (some were redundant, some could
180        be replaced by .nf/.fi pairs). The 132html script that I use to generate
181        HTML has been updated to handle .nf/.fi and to complain if it encounters
182        .br or .in.
184     4. Updated comments in configure.ac that get placed in config.h.in and also
185        arranged for config.h to be included in the distribution, with the name
186        config.h.generic, for the benefit of those who have to compile without
187        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
189     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
190        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
191        makevp.bat for the current PCRE, using the additional files
192        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
194     6. A Windows user reported a minor discrepancy with test 2, which turned out
195        to be caused by a trailing space on an input line that had got lost in his
196        copy. The trailing space was an accident, so I've just removed it.
198     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
199        that is needed.
201     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
202        as "const" (a) because they are and (b) because it helps the PHP
203        maintainers who have recently made a script to detect big data structures
204        in the php code that should be moved to the .rodata section. I remembered
205        to update Builducptable as well, so it won't revert if ucptable.h is ever
206        re-created.
208     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
209        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
210        order to be able to cut out the UTF-8 tables in the latter when UTF-8
211        support is not required. This saves 1.5-2K of code, which is important in
212        some applications.
214        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
215        so as not to refer to the tables, even though these functions will never be
216        called when UTF-8 support is disabled. Otherwise there are problems with a
217        shared library.
219    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
221        (a) It was defining its arguments as char * instead of void *.
223        (b) It was assuming that all moves were upwards in memory; this was true
224            a long time ago when I wrote it, but is no longer the case.
226        The emulated memove() is provided for those environments that have neither
227        memmove() nor bcopy(). I didn't think anyone used it these days, but that
228        is clearly not the case, as these two bugs were recently reported.
230    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
231        and Detrail to create the HTML documentation, the .txt form of the man
232        pages, and it removes trailing spaces from listed files. It also creates
233        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
234        case, it wraps all the #defines with #ifndefs. This script should be run
235        before "make dist".
237    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
238        with Unicode property support.
240        (a) For a maximizing quantifier, if the two different cases of the
241            character were of different lengths in their UTF-8 codings (there are
242            some cases like this - I found 11), and the matching function had to
243            back up over a mixture of the two cases, it incorrectly assumed they
244            were both the same length.
246        (b) When PCRE was configured to use the heap rather than the stack for
247            recursion during matching, it was not correctly preserving the data for
248            the other case of a UTF-8 character when checking ahead for a match
249            while processing a minimizing repeat. If the check also involved
250            matching a wide character, but failed, corruption could cause an
251            erroneous result when trying to check for a repeat of the original
252            character.
254    13. Some tidying changes to the testing mechanism:
256        (a) The RunTest script now detects the internal link size and whether there
257            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
258            values substituted by "configure". (The RunGrepTest script already did
259            this for UTF-8.) The configure.ac script no longer substitutes the
260            relevant variables.
262        (b) The debugging options /B and /D in pcretest show the compiled bytecode
263            with length and offset values. This means that the output is different
264            for different internal link sizes. Test 2 is skipped for link sizes
265            other than 2 because of this, bypassing the problem. Unfortunately,
266            there was also a test in test 3 (the locale tests) that used /B and
267            failed for link sizes other than 2. Rather than cut the whole test out,
268            I have added a new /Z option to pcretest that replaces the length and
269            offset values with spaces. This is now used to make test 3 independent
270            of link size. (Test 2 will be tidied up later.)
272    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
273        segmentation fault instead of returning the appropriate error message.
275    15. In multiline mode when the newline sequence was set to "any", the pattern
276        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
277        This doesn't seem right; it now treats the CRLF combination as the line
278        ending, and so does not match in that case. It's only a pattern such as ^$
279        that would hit this one: something like ^ABC$ would have failed after \r
280        and then tried again after \r\n.
282    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
283        in an attempt to make files that differ only in their line terminators
284        compare equal. This works on Linux.
286    17. Under certain error circumstances pcregrep might try to free random memory
287        as it exited. This is now fixed, thanks to valgrind.
289    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
290        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
291        was because its rules for how to advance for /g after matching an empty
292        string at the end of a line did not allow for this case. They now check for
293        it specially.
295    20. pcretest is supposed to handle patterns and data of any length, by
296        extending its buffers when necessary. It was getting this wrong when the
297        buffer for a data line had to be extended.
299    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
300        CRLF as a newline sequence.
302    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
303        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
304        I have nevertheless tidied it up.
306    23. Added some casts to kill warnings from HP-UX ia64 compiler.
308    24. Added a man page for pcre-config.
311    Version 7.0 19-Dec-06
312    ---------------------
314     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
315        moving to gcc 4.1.1.
317     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
318        sys/time.h, which is documented as needed for this function. It doesn't
319        seem to matter on Linux, but it showed up on some releases of OS X.
321     3. It seems that there are systems where bytes whose values are greater than
322        127 match isprint() in the "C" locale. The "C" locale should be the
323        default when a C program starts up. In most systems, only ASCII printing
324        characters match isprint(). This difference caused the output from pcretest
325        to vary, making some of the tests fail. I have changed pcretest so that:
327        (a) When it is outputting text in the compiled version of a pattern, bytes
328            other than 32-126 are always shown as hex escapes.
330        (b) When it is outputting text that is a matched part of a subject string,
331            it does the same, unless a different locale has been set for the match
332            (using the /L modifier). In this case, it uses isprint() to decide.
334     4. Fixed a major bug that caused incorrect computation of the amount of memory
335        required for a compiled pattern when options that changed within the
336        pattern affected the logic of the preliminary scan that determines the
337        length. The relevant options are -x, and -i in UTF-8 mode. The result was
338        that the computed length was too small. The symptoms of this bug were
339        either the PCRE error "internal error: code overflow" from pcre_compile(),
340        or a glibc crash with a message such as "pcretest: free(): invalid next
341        size (fast)". Examples of patterns that provoked this bug (shown in
342        pcretest format) are:
344          /(?-x: )/x
345          /(?x)(?-x: \s*#\s*)/
346          /((?i)[\x{c0}])/8
347          /(?i:[\x{c0}])/8
349        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
350        is now done differently.
352     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
353        wrapper classes; (b) implement a new function in the C++ scanner that is
354        more efficient than the old way of doing things because it avoids levels of
355        recursion in the regex matching; (c) add a paragraph to the documentation
356        for the FullMatch() function.
358     6. The escape sequence \n was being treated as whatever was defined as
359        "newline". Not only was this contrary to the documentation, which states
360        that \n is character 10 (hex 0A), but it also went horribly wrong when
361        "newline" was defined as CRLF. This has been fixed.
363     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
364        was being set to -1 for the "end of line" case (supposedly a value that no
365        character can have). Though this value is never used (the check for end of
366        line is "zero bytes in current character"), it caused compiler complaints.
367        I've changed it to 0xffffffff.
369     8. In pcre_version.c, the version string was being built by a sequence of
370        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
371        string (as it is for production releases) called a macro with an empty
372        argument. The C standard says the result of this is undefined. The gcc
373        compiler treats it as an empty string (which was what was wanted) but it is
374        reported that Visual C gives an error. The source has been hacked around to
375        avoid this problem.
377     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
378        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
379        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
380        of them did).
382    10. Originally, pcretest opened its input and output without "b"; then I was
383        told that "b" was needed in some environments, so it was added for release
384        5.0 to both the input and output. (It makes no difference on Unix-like
385        systems.) Later I was told that it is wrong for the input on Windows. I've
386        now abstracted the modes into two macros, to make it easier to fiddle with
387        them, and removed "b" from the input mode under Windows.
389    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
391    12. Added -help and --help to pcretest as an official way of being reminded
392        of the options.
394    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
395        and pcrecpp.cc because they annoy compilers at high warning levels.
397    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
399    15. Fixed an occurrence of == in configure.ac that should have been = (shell
400        scripts are not C programs :-) and which was not noticed because it works
401        on Linux.
403    16. pcretest is supposed to handle any length of pattern and data line (as one
404        line or as a continued sequence of lines) by extending its input buffer if
405        necessary. This feature was broken for very long pattern lines, leading to
406        a string of junk being passed to pcre_compile() if the pattern was longer
407        than about 50K.
409    17. I have done a major re-factoring of the way pcre_compile() computes the
410        amount of memory needed for a compiled pattern. Previously, there was code
411        that made a preliminary scan of the pattern in order to do this. That was
412        OK when PCRE was new, but as the facilities have expanded, it has become
413        harder and harder to keep it in step with the real compile phase, and there
414        have been a number of bugs (see for example, 4 above). I have now found a
415        cunning way of running the real compile function in a "fake" mode that
416        enables it to compute how much memory it would need, while actually only
417        ever using a few hundred bytes of working memory and without too many
418        tests of the mode. This should make future maintenance and development
419        easier. A side effect of this work is that the limit of 200 on the nesting
420        depth of parentheses has been removed (though this was never a serious
421        limitation, I suspect). However, there is a downside: pcre_compile() now
422        runs more slowly than before (30% or more, depending on the pattern). I
423        hope this isn't a big issue. There is no effect on runtime performance.
425    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
426        newline (only possible for the last line of a file) and it was a
427        pattern that set a locale (followed by /Lsomething), pcretest crashed.
429    19. Added additional timing features to pcretest. (1) The -tm option now times
430        matching only, not compiling. (2) Both -t and -tm can be followed, as a
431        separate command line item, by a number that specifies the number of
432        repeats to use when timing. The default is 50000; this gives better
433        precision, but takes uncomfortably long for very large patterns.
435    20. Extended pcre_study() to be more clever in cases where a branch of a
436        subpattern has no definite first character. For example, (a*|b*)[cd] would
437        previously give no result from pcre_study(). Now it recognizes that the
438        first character must be a, b, c, or d.
440    21. There was an incorrect error "recursive call could loop indefinitely" if
441        a subpattern (or the entire pattern) that was being tested for matching an
442        empty string contained only one non-empty item after a nested subpattern.
443        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
444        incorrectly, because the \d was being skipped in the check.
446    22. The pcretest program now has a new pattern option /B and a command line
447        option -b, which is equivalent to adding /B to every pattern. This causes
448        it to show the compiled bytecode, without the additional information that
449        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
450        is the same as /B/I).
452    23. A new optimization is now able automatically to treat some sequences such
453        as a*b as a*+b. More specifically, if something simple (such as a character
454        or a simple class like \d) has an unlimited quantifier, and is followed by
455        something that cannot possibly match the quantified thing, the quantifier
456        is automatically "possessified".
458    24. A recursive reference to a subpattern whose number was greater than 39
459        went wrong under certain circumstances in UTF-8 mode. This bug could also
460        have affected the operation of pcre_study().
462    25. Realized that a little bit of performance could be had by replacing
463        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
465    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
467    27. Possessive quantifiers such as a++ were previously implemented by turning
468        them into atomic groups such as ($>a+). Now they have their own opcodes,
469        which improves performance. This includes the automatically created ones
470        from 23 above.
472    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
473        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
474        the first matched character to be a colon. This applied both to named and
475        numbered groups.
477    29. The ucpinternal.h header file was missing its idempotency #ifdef.
479    30. I was sent a "project" file called libpcre.a.dev which I understand makes
480        building PCRE on Windows easier, so I have included it in the distribution.
482    31. There is now a check in pcretest against a ridiculously large number being
483        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
484        loop, the loop is abandoned.
486    32. Forward references to subpatterns in conditions such as (?(2)...) where
487        subpattern 2 is defined later cause pcre_compile() to search forwards in
488        the pattern for the relevant set of parentheses. This search went wrong
489        when there were unescaped parentheses in a character class, parentheses
490        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
492    33. "Subroutine" calls and backreferences were previously restricted to
493        referencing subpatterns earlier in the regex. This restriction has now
494        been removed.
496    34. Added a number of extra features that are going to be in Perl 5.10. On the
497        whole, these are just syntactic alternatives for features that PCRE had
498        previously implemented using the Python syntax or my own invention. The
499        other formats are all retained for compatibility.
501        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
502            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
503            also .NET compatible.
505        (b) A recursion or subroutine call to a named group can now be defined as
506            (?&name) as well as (?P>name).
508        (c) A backreference to a named group can now be defined as \k<name> or
509            \k'name' as well as (?P=name). The new forms, as well as being in Perl
510            5.10, are also .NET compatible.
512        (d) A conditional reference to a named group can now use the syntax
513            (?(<name>) or (?('name') as well as (?(name).
515        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
516            groups (named and numbered) that are never evaluated inline, but can be
517            called as "subroutines" from elsewhere. In effect, the DEFINE condition
518            is always false. There may be only one alternative in such a group.
520        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
521            as the simple (?(R). The condition is true only if the most recent
522            recursion is that of the given number or name. It does not search out
523            through the entire recursion stack.
525        (g) The escape \gN or \g{N} has been added, where N is a positive or
526            negative number, specifying an absolute or relative reference.
528    35. Tidied to get rid of some further signed/unsigned compiler warnings and
529        some "unreachable code" warnings.
531    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
532        things, this adds five new scripts.
534    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
535        There were also incompatibilities regarding the handling of \Q..\E inside
536        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
537        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
539    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
540        matches an empty string, and forcibly breaks the loop. There were bugs in
541        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
542        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
543        separate and independent bugs (that affected different cases) have been
544        fixed.
546    39. Refactored the code to abolish the use of different opcodes for small
547        capturing bracket numbers. This is a tidy that I avoided doing when I
548        removed the limit on the number of capturing brackets for 3.5 back in 2001.
549        The new approach is not only tidier, it makes it possible to reduce the
550        memory needed to fix the previous bug (38).
552    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
553        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
554        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
555        mode.
557    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
558        report.
560    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
561        copy construction and assignment in the C++ wrapper.
563    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
564        couple of bugs that could have given wrong results in the "--newline=crlf"
565        case.
567    44. Added a number of casts and did some reorganization of signed/unsigned int
568        variables following suggestions from Dair Grant. Also renamed the variable
569        "this" as "item" because it is a C++ keyword.
571    45. Arranged for dftables to add
573          #include "pcre_internal.h"
575        to pcre_chartables.c because without it, gcc 4.x may remove the array
576        definition from the final binary if PCRE is built into a static library and
577        dead code stripping is activated.
579    46. For an unanchored pattern, if a match attempt fails at the start of a
580        newline sequence, and the newline setting is CRLF or ANY, and the next two
581        characters are CRLF, advance by two characters instead of one.
584    Version 6.7 04-Jul-06
585    ---------------------
587     1. In order to handle tests when input lines are enormously long, pcretest has
588        been re-factored so that it automatically extends its buffers when
589        necessary. The code is crude, but this _is_ just a test program. The
590        default size has been increased from 32K to 50K.
592     2. The code in pcre_study() was using the value of the re argument before
593        testing it for NULL. (Of course, in any sensible call of the function, it
594        won't be NULL.)
596     3. The memmove() emulation function in pcre_internal.h, which is used on
597        systems that lack both memmove() and bcopy() - that is, hardly ever -
598        was missing a "static" storage class specifier.
600     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
601        containing an extended class (one that cannot be represented by a bitmap
602        because it contains high-valued characters or Unicode property items, e.g.
603        [\pZ]). Almost always one would set UTF-8 mode when processing such a
604        pattern, but PCRE should not loop if you do not (it no longer does).
605        [Detail: two cases were found: (a) a repeated subpattern containing an
606        extended class; (b) a recursive reference to a subpattern that followed a
607        previous extended class. It wasn't skipping over the extended class
608        correctly when UTF-8 mode was not set.]
610     5. A negated single-character class was not being recognized as fixed-length
611        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
612        compile error "lookbehind assertion is not fixed length".
614     6. The RunPerlTest auxiliary script was showing an unexpected difference
615        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
616        write a Perl script that can interpret lines of an input file either as
617        byte characters or as UTF-8, which is what "perltest" was being required to
618        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
619        can't do is switch easily at run time between having the "use utf8;" pragma
620        or not. In the end, I fudged it by using the RunPerlTest script to insert
621        "use utf8;" explicitly for the UTF-8 tests.
623     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
624        the end of the subject string, contrary to the documentation and to what
625        Perl does. This was true of both matching functions. Now it matches only at
626        the start of the subject and immediately after *internal* newlines.
628     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
629        a pointer to an int instead of a pointer to an unsigned long int. This
630        caused problems on 64-bit systems.
632     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
633        instance of the 'standard' template library not being so standard".
635    10. There was no check on the number of named subpatterns nor the maximum
636        length of a subpattern name. The product of these values is used to compute
637        the size of the memory block for a compiled pattern. By supplying a very
638        long subpattern name and a large number of named subpatterns, the size
639        computation could be caused to overflow. This is now prevented by limiting
640        the length of names to 32 characters, and the number of named subpatterns
641        to 10,000.
643    11. Subpatterns that are repeated with specific counts have to be replicated in
644        the compiled pattern. The size of memory for this was computed from the
645        length of the subpattern and the repeat count. The latter is limited to
646        65535, but there was no limit on the former, meaning that integer overflow
647        could in principle occur. The compiled length of a repeated subpattern is
648        now limited to 30,000 bytes in order to prevent this.
650    12. Added the optional facility to have named substrings with the same name.
652    13. Added the ability to use a named substring as a condition, using the
653        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
654        are numbers (not recommended). Forward references are permitted.
656    14. Added forward references in named backreferences (if you see what I mean).
658    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
659        pattern could run off the end of the subject. For example, the pattern
660        "(?s)(.{1,5})"8 did this with the subject "ab".
662    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
663        PCRE_CASELESS was set when matching characters that were quantified with ?
664        or *.
666    17. A character class other than a single negated character that had a minimum
667        but no maximum quantifier - for example [ab]{6,} - was not handled
668        correctly by pce_dfa_exec(). It would match only one character.
670    18. A valid (though odd) pattern that looked like a POSIX character
671        class but used an invalid character after [ (for example [[,abc,]]) caused
672        pcre_compile() to give the error "Failed: internal error: code overflow" or
673        in some cases to crash with a glibc free() error. This could even happen if
674        the pattern terminated after [[ but there just happened to be a sequence of
675        letters, a binary zero, and a closing ] in the memory that followed.
677    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
678        over the years. Originally (before any Unicode support), just the bottom 8
679        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
680        output from "man perlunicode" includes this:
682          The regular expression compiler produces polymorphic opcodes.  That
683          is, the pattern adapts to the data and automatically switches to
684          the Unicode character scheme when presented with Unicode data--or
685          instead uses a traditional byte scheme when presented with byte
686          data.
688        Sadly, a wide octal escape does not cause a switch, and in a string with
689        no other multibyte characters, these octal escapes are treated as before.
690        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
691        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
692        Unicode string.
694        I have not perpetrated such confusion in PCRE. Up till now, it took just
695        the bottom 8 bits, as in old Perl. I have now made octal escapes with
696        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
697        translate to the appropriate multibyte character.
699    29. Applied some refactoring to reduce the number of warnings from Microsoft
700        and Borland compilers. This has included removing the fudge introduced
701        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
702        a warning about an unused variable.
704    21. PCRE has not included VT (character 0x0b) in the set of whitespace
705        characters since release 4.0, because Perl (from release 5.004) does not.
706        [Or at least, is documented not to: some releases seem to be in conflict
707        with the documentation.] However, when a pattern was studied with
708        pcre_study() and all its branches started with \s, PCRE still included VT
709        as a possible starting character. Of course, this did no harm; it just
710        caused an unnecessary match attempt.
712    22. Removed a now-redundant internal flag bit that recorded the fact that case
713        dependency changed within the pattern. This was once needed for "required
714        byte" processing, but is no longer used. This recovers a now-scarce options
715        bit. Also moved the least significant internal flag bit to the most-
716        significant bit of the word, which was not previously used (hangover from
717        the days when it was an int rather than a uint) to free up another bit for
718        the future.
720    23. Added support for CRLF line endings as well as CR and LF. As well as the
721        default being selectable at build time, it can now be changed at runtime
722        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
723        specify that it is scanning data with non-default line endings.
725    24. Changed the definition of CXXLINK to make it agree with the definition of
726        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
728    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
729        recursions. This makes a big different to stack usage for some patterns.
731    26. If a subpattern containing a named recursion or subroutine reference such
732        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
733        the space required for the compiled pattern went wrong and gave too small a
734        value. Depending on the environment, this could lead to "Failed: internal
735        error: code overflow at offset 49" or "glibc detected double free or
736        corruption" errors.
738    27. Applied patches from Google (a) to support the new newline modes and (b) to
739        advance over multibyte UTF-8 characters in GlobalReplace.
741    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
742        difference for some implementation of PCRE in some Windows version.
744    29. Added some extra testing facilities to pcretest:
746        \q<number>   in a data line sets the "match limit" value
747        \Q<number>   in a data line sets the "match recursion limt" value
748        -S <number>  sets the stack size, where <number> is in megabytes
750        The -S option isn't available for Windows.
753    Version 6.6 06-Feb-06
754    ---------------------
756     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
757        in pcreposix.h. I have copied the definition from pcre.h.
759     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
760        because pcre.h is no longer a built file.
762     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
763        not normally included in the compiled code.
766    Version 6.5 01-Feb-06
767    ---------------------
769     1. When using the partial match feature with pcre_dfa_exec(), it was not
770        anchoring the second and subsequent partial matches at the new starting
771        point. This could lead to incorrect results. For example, with the pattern
772        /1234/, partially matching against "123" and then "a4" gave a match.
774     2. Changes to pcregrep:
776        (a) All non-match returns from pcre_exec() were being treated as failures
777            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
778            error message is output. Some extra information is given for the
779            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
780            probably the only errors that are likely to be caused by users (by
781            specifying a regex that has nested indefinite repeats, for instance).
782            If there are more than 20 of these errors, pcregrep is abandoned.
784        (b) A binary zero was treated as data while matching, but terminated the
785            output line if it was written out. This has been fixed: binary zeroes
786            are now no different to any other data bytes.
788        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
789            used to set a locale for matching. The --locale=xxxx long option has
790            been added (no short equivalent) to specify a locale explicitly on the
791            pcregrep command, overriding the environment variables.
793        (d) When -B was used with -n, some line numbers in the output were one less
794            than they should have been.
796        (e) Added the -o (--only-matching) option.
798        (f) If -A or -C was used with -c (count only), some lines of context were
799            accidentally printed for the final match.
801        (g) Added the -H (--with-filename) option.
803        (h) The combination of options -rh failed to suppress file names for files
804            that were found from directory arguments.
806        (i) Added the -D (--devices) and -d (--directories) options.
808        (j) Added the -F (--fixed-strings) option.
810        (k) Allow "-" to be used as a file name for -f as well as for a data file.
812        (l) Added the --colo(u)r option.
814        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
815            is not present by default.
817     3. A nasty bug was discovered in the handling of recursive patterns, that is,
818        items such as (?R) or (?1), when the recursion could match a number of
819        alternatives. If it matched one of the alternatives, but subsequently,
820        outside the recursion, there was a failure, the code tried to back up into
821        the recursion. However, because of the way PCRE is implemented, this is not
822        possible, and the result was an incorrect result from the match.
824        In order to prevent this happening, the specification of recursion has
825        been changed so that all such subpatterns are automatically treated as
826        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
828     4. I had overlooked the fact that, in some locales, there are characters for
829        which isalpha() is true but neither isupper() nor islower() are true. In
830        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
831        and ordfeminine) are like this. This affected the treatment of \w and \W
832        when they appeared in character classes, but not when they appeared outside
833        a character class. The bit map for "word" characters is now created
834        separately from the results of isalnum() instead of just taking it from the
835        upper, lower, and digit maps. (Plus the underscore character, of course.)
837     5. The above bug also affected the handling of POSIX character classes such as
838        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
839        permanent tables. Instead, the bit maps for such a class were previously
840        created as the appropriate unions of the upper, lower, and digit bitmaps.
841        Now they are created by subtraction from the [[:word:]] class, which has
842        its own bitmap.
844     6. The [[:blank:]] character class matches horizontal, but not vertical space.
845        It is created by subtracting the vertical space characters (\x09, \x0a,
846        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
847        subtraction was done in the overall bitmap for a character class, meaning
848        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
849        be recognized. This bug has been fixed.
851     7. Patches from the folks at Google:
853          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
854          real life, but is still worth protecting against".
856          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
857          regular expressions".
859          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
860          have it.
862          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
863          "configure" and the latter not, in order to fix a problem somebody had
864          with compiling the Arg class on HP-UX.
866          (e) Improve the error-handling of the C++ wrapper a little bit.
868          (f) New tests for checking recursion limiting.
870     8. The pcre_memmove() function, which is used only if the environment does not
871        have a standard memmove() function (and is therefore rarely compiled),
872        contained two bugs: (a) use of int instead of size_t, and (b) it was not
873        returning a result (though PCRE never actually uses the result).
875     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
876        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
877        returned instead of calling malloc() with an overflowing number that would
878        most likely cause subsequent chaos.
880    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
882    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
883        with this option is matched, the nmatch and pmatch options of regexec() are
884        ignored.
886    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
887        provided in case anyone wants to the the POSIX interface with UTF-8
888        strings.
890    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
891        C++ linking (needed for some HP-UX environments).
893    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
894        (unused parameter) and in the pcre_printint() function (omitted "default"
895        switch label when the default is to do nothing).
897    15. Added some code to make it possible, when PCRE is compiled as a C++
898        library, to replace subject pointers for pcre_exec() with a smart pointer
899        class, thus making it possible to process discontinuous strings.
901    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
902        much the same function. They were added by different people who were trying
903        to make PCRE easy to compile on non-Unix systems. It has been suggested
904        that PCRE_EXPORT be abolished now that there is more automatic apparatus
905        for compiling on Windows systems. I have therefore replaced it with
906        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
907        defaults to "extern" for C or "extern C" for C++, which works fine on
908        Unix-like systems. It is now possible to override the value of PCRE_DATA_
909        SCOPE with something explicit in config.h. In addition:
911        (a) pcreposix.h still had just "extern" instead of either of these macros;
912            I have replaced it with PCRE_DATA_SCOPE.
914        (b) Functions such as _pcre_xclass(), which are internal to the library,
915            but external in the C sense, all had PCRE_EXPORT in their definitions.
916            This is apparently wrong for the Windows case, so I have removed it.
917            (It makes no difference on Unix-like systems.)
919    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
920        of recursive calls to match(). This is different to MATCH_LIMIT because
921        that limits the total number of calls to match(), not all of which increase
922        the depth of recursion. Limiting the recursion depth limits the amount of
923        stack (or heap if NO_RECURSE is set) that is used. The default can be set
924        when PCRE is compiled, and changed at run time. A patch from Google adds
925        this functionality to the C++ interface.
927    18. Changes to the handling of Unicode character properties:
929        (a) Updated the table to Unicode 4.1.0.
931        (b) Recognize characters that are not in the table as "Cn" (undefined).
933        (c) I revised the way the table is implemented to a much improved format
934            which includes recognition of ranges. It now supports the ranges that
935            are defined in UnicodeData.txt, and it also amalgamates other
936            characters into ranges. This has reduced the number of entries in the
937            table from around 16,000 to around 3,000, thus reducing its size
938            considerably. I realized I did not need to use a tree structure after
939            all - a binary chop search is just as efficient. Having reduced the
940            number of entries, I extended their size from 6 bytes to 8 bytes to
941            allow for more data.
943        (d) Added support for Unicode script names via properties such as \p{Han}.
945    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
946        matching that character.
948    20. When matching a repeated Unicode property with a minimum greater than zero,
949        (for example \pL{2,}), PCRE could look past the end of the subject if it
950        reached it while seeking the minimum number of characters. This could
951        happen only if some of the characters were more than one byte long, because
952        there is a check for at least the minimum number of bytes.
954    21. Refactored the implementation of \p and \P so as to be more general, to
955        allow for more different types of property in future. This has changed the
956        compiled form incompatibly. Anybody with saved compiled patterns that use
957        \p or \P will have to recompile them.
959    22. Added "Any" and "L&" to the supported property types.
961    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
962        but give a compile time error if the value is greater than 0xff.
964    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
965        accidentally not being installed or uninstalled.
967    25. The pcre.h file was built from pcre.h.in, but the only changes that were
968        made were to insert the current release number. This seemed silly, because
969        it made things harder for people building PCRE on systems that don't run
970        "configure". I have turned pcre.h into a distributed file, no longer built
971        by "configure", with the version identification directly included. There is
972        no longer a pcre.h.in file.
974        However, this change necessitated a change to the pcre-config script as
975        well. It is built from pcre-config.in, and one of the substitutions was the
976        release number. I have updated configure.ac so that ./configure now finds
977        the release number by grepping pcre.h.
979    26. Added the ability to run the tests under valgrind.
982    Version 6.4 05-Sep-05
983    ---------------------
985     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
986        "--" to be printed when multiple files were scanned, even when none of the
987        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
988        consider it to be a bug, and have restored the previous behaviour.
990     2. A couple of code tidies to get rid of compiler warnings.
992     3. The pcretest program used to cheat by referring to symbols in the library
993        whose names begin with _pcre_. These are internal symbols that are not
994        really supposed to be visible externally, and in some environments it is
995        possible to suppress them. The cheating is now confined to including
996        certain files from the library's source, which is a bit cleaner.
998     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
999        file's purpose clearer.
1001     5. Reorganized pcre_ucp_findchar().
1004    Version 6.3 15-Aug-05
1005    ---------------------
1007     1. The file libpcre.pc.in did not have general read permission in the tarball.
1009     2. There were some problems when building without C++ support:
1011        (a) If C++ support was not built, "make install" and "make test" still
1012            tried to test it.
1014        (b) There were problems when the value of CXX was explicitly set. Some
1015            changes have been made to try to fix these, and ...
1017        (c) --disable-cpp can now be used to explicitly disable C++ support.
1019        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1020            backslash in a target when C++ was disabled. This confuses some
1021            versions of "make", apparently. Using an intermediate variable solves
1022            this. (Same for CPP_LOBJ.)
1024     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1025        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1026        necessary on certain architectures.
1028     4. Added a setting of -export-symbols-regex to the link command to remove
1029        those symbols that are exported in the C sense, but actually are local
1030        within the library, and not documented. Their names all begin with
1031        "_pcre_". This is not a perfect job, because (a) we have to except some
1032        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1033        available (and never for static libraries). I have made a note to try to
1034        find a way round (a) in the future.
1037    Version 6.2 01-Aug-05
1038    ---------------------
1040     1. There was no test for integer overflow of quantifier values. A construction
1041        such as {1111111111111111} would give undefined results. What is worse, if
1042        a minimum quantifier for a parenthesized subpattern overflowed and became
1043        negative, the calculation of the memory size went wrong. This could have
1044        led to memory overwriting.
1046     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1048     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1049        operating environments where this matters.
1051     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1052        PCRE options from within the C++ wrapper.
1054     5. Named capturing subpatterns were not being correctly counted when a pattern
1055        was compiled. This caused two problems: (a) If there were more than 100
1056        such subpatterns, the calculation of the memory needed for the whole
1057        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1058        back references of the form \12, where the number was greater than 9, were
1059        not recognized as back references, even though there were sufficient
1060        previous subpatterns.
1062     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1063        versions of gcc, e.g. 2.95.4.
1066    Version 6.1 21-Jun-05
1067    ---------------------
1069     1. There was one reference to the variable "posix" in pcretest.c that was not
1070        surrounded by "#if !defined NOPOSIX".
1072     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1073        the cross-check on the old pcre_info() function, for the benefit of the
1074        cut-down version of PCRE that is currently imported into Exim.
1076     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1077        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1078        patterns that start (?i) but I don't think that matters. The use of (?i) is
1079        just an example; this all applies to the other options as well.
1081     4. Since libtool seems to echo the compile commands it is issuing, the output
1082        from "make" can be reduced a bit by putting "@" in front of each libtool
1083        compile command.
1085     5. Patch from the folks at Google for configure.in to be a bit more thorough
1086        in checking for a suitable C++ installation before trying to compile the
1087        C++ stuff. This should fix a reported problem when a compiler was present,
1088        but no suitable headers.
1090     6. The man pages all had just "PCRE" as their title. I have changed them to
1091        be the relevant file name. I have also arranged that these names are
1092        retained in the file doc/pcre.txt, which is a concatenation in text format
1093        of all the man pages except the little individual ones for each function.
1095     7. The NON-UNIX-USE file had not been updated for the different set of source
1096        files that come with release 6. I also added a few comments about the C++
1097        wrapper.
1100    Version 6.0 07-Jun-05
1101    ---------------------
1103     1. Some minor internal re-organization to help with my DFA experiments.
1105     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1106        didn't matter for the library itself when fully configured, but did matter
1107        when compiling without UCP support, or within Exim, where the ucp files are
1108        not imported.
1110     3. Refactoring of the library code to split up the various functions into
1111        different source modules. The addition of the new DFA matching code (see
1112        below) to a single monolithic source would have made it really too
1113        unwieldy, quite apart from causing all the code to be include in a
1114        statically linked application, when only some functions are used. This is
1115        relevant even without the DFA addition now that patterns can be compiled in
1116        one application and matched in another.
1118        The downside of splitting up is that there have to be some external
1119        functions and data tables that are used internally in different modules of
1120        the library but which are not part of the API. These have all had their
1121        names changed to start with "_pcre_" so that they are unlikely to clash
1122        with other external names.
1124     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1125        a different (DFA) algorithm. Although it is slower than the original
1126        function, it does have some advantages for certain types of matching
1127        problem.
1129     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1130        including restarting after a partial match.
1132     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1133        defined when compiling for Windows was sent to me. I have put it into the
1134        code, though I have no means of testing or verifying it.
1136     7. Added the pcre_refcount() auxiliary function.
1138     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1139        match before or at the first newline in the subject string. In pcretest,
1140        the /f option on a pattern can be used to set this.
1142     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1143        would behave wrongly. This has been present in PCRE since release 4.0.
1145    10. A number of changes to the pcregrep command:
1147        (a) Refactored how -x works; insert ^(...)$ instead of setting
1148            PCRE_ANCHORED and checking the length, in preparation for adding
1149            something similar for -w.
1151        (b) Added the -w (match as a word) option.
1153        (c) Refactored the way lines are read and buffered so as to have more
1154            than one at a time available.
1156        (d) Implemented a pcregrep test script.
1158        (e) Added the -M (multiline match) option. This allows patterns to match
1159            over several lines of the subject. The buffering ensures that at least
1160            8K, or the rest of the document (whichever is the shorter) is available
1161            for matching (and similarly the previous 8K for lookbehind assertions).
1163        (f) Changed the --help output so that it now says
1165              -w, --word-regex(p)
1167            instead of two lines, one with "regex" and the other with "regexp"
1168            because that confused at least one person since the short forms are the
1169            same. (This required a bit of code, as the output is generated
1170            automatically from a table. It wasn't just a text change.)
1172        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1173            option but starts with a hyphen. Could be a pattern or a path name
1174            starting with a hyphen, for instance.
1176        (h) "-" can be given as a file name to represent stdin.
1178        (i) When file names are being printed, "(standard input)" is used for
1179            the standard input, for compatibility with GNU grep. Previously
1180            "<stdin>" was used.
1182        (j) The option --label=xxx can be used to supply a name to be used for
1183            stdin when file names are being printed. There is no short form.
1185        (k) Re-factored the options decoding logic because we are going to add
1186            two more options that take data. Such options can now be given in four
1187            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1189        (l) Added the -A, -B, and -C options for requesting that lines of context
1190            around matches be printed.
1192        (m) Added the -L option to print the names of files that do not contain
1193            any matching lines, that is, the complement of -l.
1195        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1196            continue to scan other files.
1198        (o) The -s option was incorrectly implemented. For compatibility with other
1199            greps, it now suppresses the error message for a non-existent or non-
1200            accessible file (but not the return code). There is a new option called
1201            -q that suppresses the output of matching lines, which was what -s was
1202            previously doing.
1204        (p) Added --include and --exclude options to specify files for inclusion
1205            and exclusion when recursing.
1207    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1208        Hopefully, it now does.
1210    12. Missing cast in pcre_study().
1212    13. Added an "uninstall" target to the makefile.
1214    14. Replaced "extern" in the function prototypes in Makefile.in with
1215        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1216        world, but is set differently for Windows.
1218    15. Added a second compiling function called pcre_compile2(). The only
1219        difference is that it has an extra argument, which is a pointer to an
1220        integer error code. When there is a compile-time failure, this is set
1221        non-zero, in addition to the error test pointer being set to point to an
1222        error message. The new argument may be NULL if no error number is required
1223        (but then you may as well call pcre_compile(), which is now just a
1224        wrapper). This facility is provided because some applications need a
1225        numeric error indication, but it has also enabled me to tidy up the way
1226        compile-time errors are handled in the POSIX wrapper.
1228    16. Added VPATH=.libs to the makefile; this should help when building with one
1229        prefix path and installing with another. (Or so I'm told by someone who
1230        knows more about this stuff than I do.)
1232    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1233        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1234        match everything, including newlines. This is not POSIX-compatible, but
1235        somebody wanted the feature. From pcretest it can be activated by using
1236        both the P and the s flags.
1238    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1240    19. libpcre.pc was being incorrectly installed as executable.
1242    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1243        it now also looks for '\r' so that it will work unmodified on Windows.
1245    21. Added Google's contributed C++ wrapper to the distribution.
1247    22. Added some untidy missing memory free() calls in pcretest, to keep
1248        Electric Fence happy when testing.
1252    Version 5.0 13-Sep-04
1253    ---------------------
1255     1. Internal change: literal characters are no longer packed up into items
1256        containing multiple characters in a single byte-string. Each character
1257        is now matched using a separate opcode. However, there may be more than one
1258        byte in the character in UTF-8 mode.
1260     2. The pcre_callout_block structure has two new fields: pattern_position and
1261        next_item_length. These contain the offset in the pattern to the next match
1262        item, and its length, respectively.
1264     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1265        insertion of callouts before each pattern item. Added the /C option to
1266        pcretest to make use of this.
1268     4. On the advice of a Windows user, the lines
1270          #if defined(_WIN32) || defined(WIN32)
1271          _setmode( _fileno( stdout ), 0x8000 );
1272          #endif  /* defined(_WIN32) || defined(WIN32) */
1274        have been added to the source of pcretest. This apparently does useful
1275        magic in relation to line terminators.
1277     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1278        for the benefit of those environments where the "b" makes a difference.
1280     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1281        to know about it. I have put a hack into configure.in that adds in code
1282        to set GCC=yes if CC=icc. This seems to end up at a point in the
1283        generated configure script that is early enough to affect the setting of
1284        compiler options, which is what is needed, but I have no means of testing
1285        whether it really works. (The user who reported this had patched the
1286        generated configure script, which of course I cannot do.)
1288        LATER: After change 22 below (new libtool files), the configure script
1289        seems to know about icc (and also ecc). Therefore, I have commented out
1290        this hack in configure.in.
1292     7. Added support for pkg-config (2 patches were sent in).
1294     8. Negated POSIX character classes that used a combination of internal tables
1295        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1296        [[:^ascii]]. Typically, they would match almost any characters. The other
1297        POSIX classes were not broken in this way.
1299     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1300        to find the match, as PCRE was deluded into thinking that the match had to
1301        start at the start point or following a newline. The same bug applied to
1302        patterns with negative forward assertions or any backward assertions
1303        preceding ".*" at the start, unless the pattern required a fixed first
1304        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1306    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1307        starting at the last subject character, bytes beyond the end of the subject
1308        string were read.
1310    11. Renamed the variable "class" as "classbits" to make life easier for C++
1311        users. (Previously there was a macro definition, but it apparently wasn't
1312        enough.)
1314    12. Added the new field "tables" to the extra data so that tables can be passed
1315        in at exec time, or the internal tables can be re-selected. This allows
1316        a compiled regex to be saved and re-used at a later time by a different
1317        program that might have everything at different addresses.
1319    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1320        -R library as well as a -L library.
1322    14. The debugging options of pcretest (-d on the command line or D on a
1323        pattern) showed incorrect output for anything following an extended class
1324        that contained multibyte characters and which was followed by a quantifier.
1326    15. Added optional support for general category Unicode character properties
1327        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1328        support. It adds about 90K to the size of the library. The meanings of the
1329        inbuilt class escapes such as \d and \s have NOT been changed.
1331    16. Updated pcredemo.c to include calls to free() to release the memory for the
1332        compiled pattern.
1334    17. The generated file chartables.c was being created in the source directory
1335        instead of in the building directory. This caused the build to fail if the
1336        source directory was different from the building directory, and was
1337        read-only.
1339    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1340        file. No doubt somebody will tell me if they don't make sense... Also added
1341        Dan Mooney's comments about building on OpenVMS.
1343    19. Added support for partial matching via the PCRE_PARTIAL option for
1344        pcre_exec() and the \P data escape in pcretest.
1346    20. Extended pcretest with 3 new pattern features:
1348        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1349              write the compiled pattern to the file whose name is "rest-of-line".
1350              This is a straight binary dump of the data, with the saved pointer to
1351              the character tables forced to be NULL. The study data, if any, is
1352              written too. After writing, pcretest reads a new pattern.
1354        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1355              compiled pattern from the given file. There must not be any
1356              occurrences of "<" in the file name (pretty unlikely); if there are,
1357              pcretest will instead treat the initial "<" as a pattern delimiter.
1358              After reading in the pattern, pcretest goes on to read data lines as
1359              usual.
1361        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1362              and 16-bit fields in a compiled pattern, to simulate a pattern that
1363              was compiled on a host of opposite endianness.
1365    21. The pcre-exec() function can now cope with patterns that were compiled on
1366        hosts of opposite endianness, with this restriction:
1368          As for any compiled expression that is saved and used later, the tables
1369          pointer field cannot be preserved; the extra_data field in the arguments
1370          to pcre_exec() should be used to pass in a tables address if a value
1371          other than the default internal tables were used at compile time.
1373    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1374        now diagnosed as an error. Previously, most of the time, a negative number
1375        would have been treated as zero, but if in addition "ovector" was passed as
1376        NULL, a crash could occur.
1378    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1379        new versions from the libtool 1.5 distribution (the last one is a copy of
1380        a file called libtool.m4). This seems to have fixed the need to patch
1381        "configure" to support Darwin 1.3 (which I used to do). However, I still
1382        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1383        workstation).
1385    24. Changed the PCRE licence to be the more standard "BSD" licence.
1388    Version 4.5 01-Dec-03
1389    ---------------------
1391     1. There has been some re-arrangement of the code for the match() function so
1392        that it can be compiled in a version that does not call itself recursively.
1393        Instead, it keeps those local variables that need separate instances for
1394        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1395        needs to "recurse". Keeping track of where control must go is done by means
1396        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1397        hide most of the details from the main code, and operates only if
1398        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1399        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1400        operating.
1402        To make it easier for callers to provide specially tailored get/free
1403        functions for this usage, two new functions, pcre_stack_malloc, and
1404        pcre_stack_free, are used. They are always called in strict stacking order,
1405        and the size of block requested is always the same.
1407        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1408        PCRE has been compiled to use the stack or the heap for recursion. The
1409        -C option of pcretest uses this to show which version is compiled.
1411        A new data escape \S, is added to pcretest; it causes the amounts of store
1412        obtained and freed by both kinds of malloc/free at match time to be added
1413        to the output.
1415     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1416        what's available on my current Linux desktop machine.
1418     3. When matching a UTF-8 string, the test for a valid string at the start has
1419        been extended. If start_offset is not zero, PCRE now checks that it points
1420        to a byte that is the start of a UTF-8 character. If not, it returns
1421        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1422        this is necessary because there may be backward assertions in the pattern.
1423        When matching the same subject several times, it may save resources to use
1424        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1426     4. The code for checking the validity of UTF-8 strings has been tightened so
1427        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1428        containing "overlong sequences".
1430     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1431        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1432        should have been "&", but it just so happened that all the cases this let
1433        through by mistake were picked up later in the function.
1435     6. I had used a variable called "isblank" - this is a C99 function, causing
1436        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1438     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1439        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1440        so the version is shown; (c) stop "make test" echoing "./RunTest".
1442     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1444     9. The prototype for memmove() for systems that don't have it was using
1445        size_t, but the inclusion of the header that defines size_t was later. I've
1446        moved the #includes for the C headers earlier to avoid this.
1448    10. Added some adjustments to the code to make it easier to compiler on certain
1449        special systems:
1451          (a) Some "const" qualifiers were missing.
1452          (b) Added the macro EXPORT before all exported functions; by default this
1453              is defined to be empty.
1454          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1455              that it reads its output file name as an argument instead of writing
1456              to the standard output and assuming this can be redirected.
1458    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1459        class containing characters with values greater than 255, PCRE compilation
1460        went into a loop.
1462    12. A recursive reference to a subpattern that was within another subpattern
1463        that had a minimum quantifier of zero caused PCRE to crash. For example,
1464        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1465        recursion. If the recursively-called subpattern itself had a zero repeat,
1466        that was OK.
1468    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1469        buffer into which it was copied (for escape processing) was still set at
1470        1024, so long lines caused crashes.
1472    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1473        "internal error: code overflow...". This applied to any character class
1474        that was followed by a possessive quantifier.
1476    15. Modified the Makefile to add libpcre.la as a prerequisite for
1477        libpcreposix.la because I was told this is needed for a parallel build to
1478        work.
1480    16. If a pattern that contained .* following optional items at the start was
1481        studied, the wrong optimizing data was generated, leading to matching
1482        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1483        matching string must start with a or b or c. The correct conclusion for
1484        this pattern is that a match can start with any character.
1487    Version 4.4 13-Aug-03
1488    ---------------------
1490     1. In UTF-8 mode, a character class containing characters with values between
1491        127 and 255 was not handled correctly if the compiled pattern was studied.
1492        In fixing this, I have also improved the studying algorithm for such
1493        classes (slightly).
1495     2. Three internal functions had redundant arguments passed to them. Removal
1496        might give a very teeny performance improvement.
1498     3. Documentation bug: the value of the capture_top field in a callout is *one
1499        more than* the number of the hightest numbered captured substring.
1501     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1502        in incorrectly linking with a previously installed version. They now link
1503        explicitly with libpcre.la.
1505     5. configure.in no longer needs to recognize Cygwin specially.
1507     6. A problem in pcre.in for Windows platforms is fixed.
1509     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1510        pcretest, it used to include the size of the study block as part of its
1511        output. Unfortunately, the structure contains a field that has a different
1512        size on different hardware architectures. This meant that the tests that
1513        showed this size failed. As the block is currently always of a fixed size,
1514        this information isn't actually particularly useful in pcretest output, so
1515        I have just removed it.
1517     8. Three pre-processor statements accidentally did not start in column 1.
1518        Sadly, there are *still* compilers around that complain, even though
1519        standard C has not required this for well over a decade. Sigh.
1521     9. In pcretest, the code for checking callouts passed small integers in the
1522        callout_data field, which is a void * field. However, some picky compilers
1523        complained about the casts involved for this on 64-bit systems. Now
1524        pcretest passes the address of the small integer instead, which should get
1525        rid of the warnings.
1527    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1528        both compile and run time, and gives an error if an invalid UTF-8 sequence
1529        is found. There is a option for disabling this check in cases where the
1530        string is known to be correct and/or the maximum performance is wanted.
1532    11. In response to a bug report, I changed one line in Makefile.in from
1534            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1535        to
1536            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1538        to look similar to other lines, but I have no way of telling whether this
1539        is the right thing to do, as I do not use Windows. No doubt I'll get told
1540        if it's wrong...
1543    Version 4.3 21-May-03
1544    ---------------------
1546    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1547       Makefile.
1549    2. Some refactoring to improve the quality of the code:
1551       (i)   The utf8_table... variables are now declared "const".
1553       (ii)  The code for \cx, which used the "case flipping" table to upper case
1554             lower case letters, now just substracts 32. This is ASCII-specific,
1555             but the whole concept of \cx is ASCII-specific, so it seems
1556             reasonable.
1558       (iii) PCRE was using its character types table to recognize decimal and
1559             hexadecimal digits in the pattern. This is silly, because it handles
1560             only 0-9, a-f, and A-F, but the character types table is locale-
1561             specific, which means strange things might happen. A private
1562             table is now used for this - though it costs 256 bytes, a table is
1563             much faster than multiple explicit tests. Of course, the standard
1564             character types table is still used for matching digits in subject
1565             strings against \d.
1567       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1568             ending in _t are). So I've renamed it as ESC_tee.
1570    3. The first argument for regexec() in the POSIX wrapper should have been
1571       defined as "const".
1573    4. Changed pcretest to use malloc() for its buffers so that they can be
1574       Electric Fenced for debugging.
1576    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1577       to read one or more bytes before the start of the subject string. Often this
1578       had no effect on PCRE's behaviour, but in some circumstances it could
1579       provoke a segmentation fault.
1581    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1582       to try to read one or more bytes before the start of the subject string.
1584    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1585       UTF-8 support could misbehave in various ways if the subject string
1586       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1587       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1588       back over UTF-8 characters.)
1591    Version 4.2 14-Apr-03
1592    ---------------------
1594    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1596    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1597         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1598         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1599         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1600         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1601           and BUILD_EXEEXT
1602         Note: automatic setting of the BUILD variables is not yet working
1603         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1604           compile-time but not at link-time
1605         [LINK]: use for linking executables only
1606         make different versions for Windows and non-Windows
1607         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1608           libraries
1609         [LINK_FOR_BUILD]: new variable
1610         [OBJEXT]: use throughout
1611         [EXEEXT]: use throughout
1612         <winshared>: new target
1613         <wininstall>: new target
1614         <dftables.o>: use native compiler
1615         <dftables>: use native linker
1616         <install>: handle Windows platform correctly
1617         <clean>: ditto
1618         <check>: ditto
1619         copy DLL to top builddir before testing
1621       As part of these changes, -no-undefined was removed again. This was reported
1622       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1623       in any case.
1625    3. Some tidies to get rid of compiler warnings:
1627       . In the match_data structure, match_limit was an unsigned long int, whereas
1628         match_call_count was an int. I've made them both unsigned long ints.
1630       . In pcretest the fact that a const uschar * doesn't automatically cast to
1631         a void * provoked a warning.
1633       . Turning on some more compiler warnings threw up some "shadow" variables
1634         and a few more missing casts.
1636    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1637       option, a class that contained a single character with a value between 128
1638       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1640    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1641       option, a class that contained several characters, but with at least one
1642       whose value was between 128 and 255 caused PCRE to crash.
1645    Version 4.1 12-Mar-03
1646    ---------------------
1648    1. Compiling with gcc -pedantic found a couple of places where casts were
1649    needed, and a string in dftables.c that was longer than standard compilers are
1650    required to support.
1652    2. Compiling with Sun's compiler found a few more places where the code could
1653    be tidied up in order to avoid warnings.
1655    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1656    first of these names is deprecated in the latest Autoconf in favour of the name
1657    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1658    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1659    analogy I have changed it to CFLAGS_FOR_BUILD.
1661    4. Added -no-undefined to the linking command in the Makefile, because this is
1662    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1663    linking step for the pcreposix library.
1665    5. PCRE was failing to diagnose the case of two named groups with the same
1666    name.
1668    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1669    literal character that is needed in the subject for a match, and scans along to
1670    ensure that it is present before embarking on the full matching process. This
1671    saves time in cases of nested unlimited repeats that are never going to match.
1672    Problem: the scan can take a lot of time if the subject is very long (e.g.
1673    megabytes), thus penalizing straightforward matches. It is now done only if the
1674    amount of subject to be scanned is less than 1000 bytes.
1676    7. A lesser problem with the same optimization is that it was recording the
1677    first character of an anchored pattern as "needed", thus provoking a search
1678    right along the subject, even when the first match of the pattern was going to
1679    fail. The "needed" character is now not set for anchored patterns, unless it
1680    follows something in the pattern that is of non-fixed length. Thus, it still
1681    fulfils its original purpose of finding quick non-matches in cases of nested
1682    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1685    Version 4.0 17-Feb-03
1686    ---------------------
1688    1. If a comment in an extended regex that started immediately after a meta-item
1689    extended to the end of string, PCRE compiled incorrect data. This could lead to
1690    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1692    2. Moved to autoconf 2.53 and libtool 1.4.2.
1694    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1695    the special perltest8 script is no longer needed - all the tests can be run
1696    from a single perltest script.
1698    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1699    by \s. It has now been removed in PCRE. This means it isn't recognized as
1700    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1701    class [:space:] *does* include VT, thereby creating a mess.
1703    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1704    space and tab.
1706    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1707    its new features into the main test script, reducing the number of scripts.
1709    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1710    were backward compatible, and made the (?i) apply to the whole pattern, as if
1711    /i were given. Now it behaves more logically, and applies the option setting
1712    only to what follows. PCRE has been changed to follow suit. However, if it
1713    finds options settings right at the start of the pattern, it extracts them into
1714    the global options, as before. Thus, they show up in the info data.
1716    8. Added support for the \Q...\E escape sequence. Characters in between are
1717    treated as literals. This is slightly different from Perl in that $ and @ are
1718    also handled as literals inside the quotes. In Perl, they will cause variable
1719    interpolation. Note the following examples:
1721        Pattern            PCRE matches      Perl matches
1723        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1724        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1725        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1727    For compatibility with Perl, \Q...\E sequences are recognized inside character
1728    classes as well as outside them.
1730    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1731    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1732    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1733    signed/unsigned warnings.
1735    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1736    option for pcretest, so I've replaced it by a simple function that does just
1737    that job.
1739    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1740    "pcregrep -".
1742    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1743    Java package. This provides some syntactic sugar for simple cases of what my
1744    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1745    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1746    item, you can use this simplified notation. Note that only makes sense with
1747    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1748    greediness, whatever the setting of the PCRE_UNGREEDY option.
1750    13. A change of greediness default within a pattern was not taking effect at
1751    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1752    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1753    was abstracted outside.
1755    14. PCRE now supports the \G assertion. It is true when the current matching
1756    position is at the start point of the match. This differs from \A when the
1757    starting offset is non-zero. Used with the /g option of pcretest (or similar
1758    code), it works in the same way as it does for Perl's /g option. If all
1759    alternatives of a regex begin with \G, the expression is anchored to the start
1760    match position, and the "anchored" flag is set in the compiled expression.
1762    15. Some bugs concerning the handling of certain option changes within patterns
1763    have been fixed. These applied to options other than (?ims). For example,
1764    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1765    been the other way round. Some of this was related to change 7 above.
1767    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1768    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1769    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1770    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1772    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1773    mode. Unlike ".", it always matches newline, whatever the setting of
1774    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1775    assertions. Perl allows it, but it doesn't (in general) work because it can't
1776    calculate the length of the lookbehind. At least, that's the case for Perl
1777    5.8.0 - I've been told they are going to document that it doesn't work in
1778    future.
1780    18. Added an error diagnosis for escapes that PCRE does not support: these are
1781    \L, \l, \N, \P, \p, \U, \u, and \X.
1783    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1784    reading past the end of the pattern in cases such as /[abcd/.
1786    20. PCRE was getting more memory than necessary for patterns with classes that
1787    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1789    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1790    compiling PCRE for use with Virtual Pascal.
1792    22. Small fix to the Makefile to make it work properly if the build is done
1793    outside the source tree.
1795    23. Added a new extension: a condition to go with recursion. If a conditional
1796    subpattern starts with (?(R) the "true" branch is used if recursion has
1797    happened, whereas the "false" branch is used only at the top level.
1799    24. When there was a very long string of literal characters (over 255 bytes
1800    without UTF support, over 250 bytes with UTF support), the computation of how
1801    much memory was required could be incorrect, leading to segfaults or other
1802    strange effects.
1804    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1805    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1806    there was a subsequent back reference to those brackets. This meant that, for
1807    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1808    possible to check for precisely this case. All we can do is abandon the
1809    optimization if .* occurs inside capturing brackets when there are any back
1810    references whatsoever. (See below for a better fix that came later.)
1812    26. The handling of the optimization for finding the first character of a
1813    non-anchored pattern, and for finding a character that is required later in the
1814    match were failing in some cases. This didn't break the matching; it just
1815    failed to optimize when it could. The way this is done has been re-implemented.
1817    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1819    28. Added a new feature that provides some of the functionality that Perl
1820    provides with (?{...}). The facility is termed a "callout". The way it is done
1821    in PCRE is for the caller to provide an optional function, by setting
1822    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1823    global variable. By default it is unset, which disables all calling out. To get
1824    the function called, the regex must include (?C) at appropriate points. This
1825    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1826    This provides a means of identifying different callout points. When PCRE
1827    reaches such a point in the regex, if pcre_callout has been set, the external
1828    function is called. It is provided with data in a structure called
1829    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1830    matching continues; if it returns a non-zero value, the match at the current
1831    point fails. However, backtracking will occur if possible. [This was changed
1832    later and other features added - see item 49 below.]
1834    29. pcretest is upgraded to test the callout functionality. It provides a
1835    callout function that displays information. By default, it shows the start of
1836    the match and the current position in the text. There are some new data escapes
1837    to vary what happens:
1839        \C+         in addition, show current contents of captured substrings
1840        \C-         do not supply a callout function
1841        \C!n        return 1 when callout number n is reached
1842        \C!n!m      return 1 when callout number n is reached for the mth time
1844    30. If pcregrep was called with the -l option and just a single file name, it
1845    output "<stdin>" if a match was found, instead of the file name.
1847    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1848    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1849    pcre_exec(). This saves a malloc/free per call. The default value of
1850    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1851    when configuring.
1853    32. The default maximum size of a compiled pattern is 64K. There have been a
1854    few cases of people hitting this limit. The code now uses macros to handle the
1855    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1856    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1857    configuring. Tests 2 and 5 work only with 2-byte links because they output
1858    debugging information about compiled patterns.
1860    33. Internal code re-arrangements:
1862    (a) Moved the debugging function for printing out a compiled regex into
1863        its own source file (printint.c) and used #include to pull it into
1864        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1865        separate copies.
1867    (b) Defined the list of op-code names for debugging as a macro in
1868        internal.h so that it is next to the definition of the opcodes.
1870    (c) Defined a table of op-code lengths for simpler skipping along compiled
1871        code. This is again a macro in internal.h so that it is next to the
1872        definition of the opcodes.
1874    34. Added support for recursive calls to individual subpatterns, along the
1875    lines of Robin Houston's patch (but implemented somewhat differently).
1877    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1878    allow it to read and process whole directories in Win32. This code was
1879    contributed by Lionel Fourquaux; it has not been tested by me.
1881    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1882    used to name a group. Names consist of alphanumerics and underscores, and must
1883    be unique. Back references use the syntax (?P=name) and recursive calls use
1884    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1885    numbers. The function pcre_fullinfo() can be used after compilation to extract
1886    a name/number map. There are three relevant calls:
1888      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1889      PCRE_INFO_NAMECOUNT            yields the number of entries
1890      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1892    The map is a vector of fixed-size entries. The size of each entry depends on
1893    the length of the longest name used. The first two bytes of each entry are the
1894    group number, most significant byte first. There follows the corresponding
1895    name, zero terminated. The names are in alphabetical order.
1897    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1898    case instead of 255. Making it the same both with and without UTF-8 support
1899    means that the same test output works with both.
1901    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1902    calling malloc() with a zero argument.
1904    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1905    optimization. I've improved things by keeping a bitmap of backreferences with
1906    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1907    fact referenced, the optimization can be applied. It is unlikely that a
1908    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1909    the match to follow \n) will appear inside brackets with a number greater than
1910    31, but if it does, any back reference > 31 suppresses the optimization.
1912    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1913    of disabling numbered capturing parentheses. Any opening parenthesis that is
1914    not followed by ? behaves as if it were followed by ?: but named parentheses
1915    can still be used for capturing (and they will acquire numbers in the usual
1916    way).
1918    41. Redesigned the return codes from the match() function into yes/no/error so
1919    that errors can be passed back from deep inside the nested calls. A malloc
1920    failure while inside a recursive subpattern call now causes the
1921    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1923    42. It is now possible to set a limit on the number of times the match()
1924    function is called in a call to pcre_exec(). This facility makes it possible to
1925    limit the amount of recursion and backtracking, though not in a directly
1926    obvious way, because the match() function is used in a number of different
1927    circumstances. The count starts from zero for each position in the subject
1928    string (for non-anchored patterns). The default limit is, for compatibility, a
1929    large number, namely 10 000 000. You can change this in two ways:
1931    (a) When configuring PCRE before making, you can use --with-match-limit=n
1932        to set a default value for the compiled library.
1934    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1935        a different value is set. See 45 below.
1937    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1939    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1940    of things that can be changed at compile time. The first argument specifies
1941    what is wanted and the second points to where the information is to be placed.
1942    The current list of available information is:
1944      PCRE_CONFIG_UTF8
1946    The output is an integer that is set to one if UTF-8 support is available;
1947    otherwise it is set to zero.
1951    The output is an integer that it set to the value of the code that is used for
1952    newline. It is either LF (10) or CR (13).
1956    The output is an integer that contains the number of bytes used for internal
1957    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1961    The output is an integer that contains the threshold above which the POSIX
1962    interface uses malloc() for output vectors. See item 31 above.
1966    The output is an unsigned integer that contains the default limit of the number
1967    of match() calls in a pcre_exec() execution. See 42 above.
1969    44. pcretest has been upgraded by the addition of the -C option. This causes it
1970    to extract all the available output from the new pcre_config() function, and to
1971    output it. The program then exits immediately.
1973    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1974    order to support additional features. One way would have been to define
1975    pcre_exec2() (for example) with extra arguments, but this would not have been
1976    extensible, and would also have required all calls to the original function to
1977    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1978    is used for passing in "extra" data from pcre_study().
1980    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1981    contains the following fields:
1983      flags         a bitmap indicating which of the following fields are set
1984      study_data    opaque data from pcre_study()
1985      match_limit   a way of specifying a limit on match() calls for a specific
1986                      call to pcre_exec()
1987      callout_data  data for callouts (see 49 below)
1989    The flag bits are also defined in pcre.h, and are
1995    The pcre_study() function now returns one of these new pcre_extra blocks, with
1996    the actual study data pointed to by the study_data field, and the
1997    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1998    before. That is, this change is entirely upwards-compatible and requires no
1999    change to existing code.
2001    If you want to pass in additional data to pcre_exec(), you can either place it
2002    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2003    block.
2005    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2006    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2007    times with different match limits, until it finds the minimum value needed for
2008    pcre_exec() to complete. The value is then output. This can be instructive; for
2009    most simple matches the number is quite small, but for pathological cases it
2010    gets very large very quickly.
2012    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2013    returns the size of the data block pointed to by the study_data field in a
2014    pcre_extra block, that is, the value that was passed as the argument to
2015    pcre_malloc() when PCRE was getting memory in which to place the information
2016    created by pcre_study(). The fourth argument should point to a size_t variable.
2017    pcretest has been extended so that this information is shown after a successful
2018    pcre_study() call when information about the compiled regex is being displayed.
2020    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2021    because what follows is always an absolute path. (Later: it turns out that this
2022    is more than cosmetic for MinGW, because it doesn't like empty path
2023    components.)
2025    49. Some changes have been made to the callout feature (see 28 above):
2027    (i)  A callout function now has three choices for what it returns:
2029           0  =>  success, carry on matching
2030         > 0  =>  failure at this point, but backtrack if possible
2031         < 0  =>  serious error, return this value from pcre_exec()
2033         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2034         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2035         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2036         use by callout functions. It will never be used by PCRE itself.
2038    (ii) The pcre_extra structure (see 45 above) has a void * field called
2039         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2040         pcre_callout_block structure has a field of the same name. The contents of
2041         the field passed in the pcre_extra structure are passed to the callout
2042         function in the corresponding field in the callout block. This makes it
2043         easier to use the same callout-containing regex from multiple threads. For
2044         testing, the pcretest program has a new data escape
2046           \C*n        pass the number n (may be negative) as callout_data
2048         If the callout function in pcretest receives a non-zero value as
2049         callout_data, it returns that value.
2051    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2052    there were some redundant $(CFLAGS) in commands that are now specified as
2053    $(LINK), which already includes $(CFLAGS).
2055    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2056    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2057    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2058    one-byte characters throughout. Note that case-insensitive matching applies
2059    only to characters whose values are less than 256. PCRE doesn't support the
2060    notion of cases for higher-valued characters.
2062    (i)   A character class whose characters are all within 0-255 is handled as
2063          a bit map, and the map is inverted for negative classes. Previously, a
2064          character > 255 always failed to match such a class; however it should
2065          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2067    (ii)  A negated character class with a single character < 255 is coded as
2068          "not this character" (OP_NOT). This wasn't working properly when the test
2069          character was multibyte, either singly or repeated.
2071    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2072          mode, for example: \x{100}{2,3}.
2074    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2075          singly or repeated) now correctly test multibyte characters. However,
2076          PCRE doesn't recognize any characters with values greater than 255 as
2077          digits, spaces, or word characters. Such characters always match \D, \S,
2078          and \W, and never match \d, \s, or \w.
2080    (v)   Classes may now contain characters and character ranges with values
2081          greater than 255. For example: [ab\x{100}-\x{400}].
2083    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2084          PCRE in UTF-8 mode.
2086    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2087    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2088    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2089    value.)
2091    53. The single man page has become too large. I have therefore split it up into
2092    a number of separate man pages. These also give rise to individual HTML pages;
2093    these are now put in a separate directory, and there is an index.html page that
2094    lists them all. Some hyperlinking between the pages has been installed.
2096    54. Added convenience functions for handling named capturing parentheses.
2098    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2099    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2100    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2101    are faulted.
2103    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2104    calling configure. These values are used when compiling the dftables.c program
2105    which is run to generate the source of the default character tables. They
2106    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2107    you will need to set these values.
2109    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2112    Version 3.9 02-Jan-02
2113    ---------------------
2115    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2117    2. If --disable-static was given, the building process failed when trying to
2118    build pcretest and pcregrep. (For some reason it was using libtool to compile
2119    them, which is not right, as they aren't part of the library.)
2122    Version 3.8 18-Dec-01
2123    ---------------------
2125    1. The experimental UTF-8 code was completely screwed up. It was packing the
2126    bytes in the wrong order. How dumb can you get?
2129    Version 3.7 29-Oct-01
2130    ---------------------
2132    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2133    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2134    this didn't happen under Solaris 8, where I normally test things.
2136    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2137    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2138    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2139    this fix an hour or so after the initial 3.7 release.)
2142    Version 3.6 23-Oct-01
2143    ---------------------
2145    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2146    offsets passed as NULL with zero offset count.
2148    2. The config.guess and config.sub files had not been updated when I moved to
2149    the latest autoconf.
2152    Version 3.5 15-Aug-01
2153    ---------------------
2155    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2156    had been forgotten.
2158    2. By using declared but undefined structures, we can avoid using "void"
2159    definitions in pcre.h while keeping the internal definitions of the structures
2160    private.
2162    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2163    user point of view, this means that both static and shared libraries are built
2164    by default, but this can be individually controlled. More of the work of
2165    handling this static/shared cases is now inside libtool instead of PCRE's make
2166    file.
2168    4. The pcretest utility is now installed along with pcregrep because it is
2169    useful for users (to test regexs) and by doing this, it automatically gets
2170    relinked by libtool. The documentation has been turned into a man page, so
2171    there are now .1, .txt, and .html versions in /doc.
2173    5. Upgrades to pcregrep:
2174       (i)   Added long-form option names like gnu grep.
2175       (ii)  Added --help to list all options with an explanatory phrase.
2176       (iii) Added -r, --recursive to recurse into sub-directories.
2177       (iv)  Added -f, --file to read patterns from a file.
2179    6. pcre_exec() was referring to its "code" argument before testing that
2180    argument for NULL (and giving an error if it was NULL).
2182    7. Upgraded Makefile.in to allow for compiling in a different directory from
2183    the source directory.
2185    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2186    options bits, the pointer it was passed was to an int instead of to an unsigned
2187    long int. This mattered only on 64-bit systems.
2189    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2190    generated) instead of pcre.in, which it its source. Also made the same change
2191    in several of the .c files.
2193    10. A new release of gcc defines printf() as a macro, which broke pcretest
2194    because it had an ifdef in the middle of a string argument for printf(). Fixed
2195    by using separate calls to printf().
2197    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2198    script, to force use of CR or LF instead of \n in the source. On non-Unix
2199    systems, the value can be set in config.h.
2201    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2202    absolute limit. Changed the text of the error message to make this clear, and
2203    likewise updated the man page.
2205    13. The limit of 99 on the number of capturing subpatterns has been removed.
2206    The new limit is 65535, which I hope will not be a "real" limit.
2209    Version 3.4 22-Aug-00
2210    ---------------------
2212    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2214    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2217    Version 3.3 01-Aug-00
2218    ---------------------
2220    1. If an octal character was given, but the value was greater than \377, it
2221    was not getting masked to the least significant bits, as documented. This could
2222    lead to crashes in some systems.
2224    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2225    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2227    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2228    These just pass their arguments on to (pcre_free)(), but they are provided
2229    because some uses of PCRE bind it to non-C systems that can call its functions,
2230    but cannot call free() or pcre_free() directly.
2232    4. Add "make test" as a synonym for "make check". Corrected some comments in
2233    the Makefile.
2235    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2236    Makefile.
2238    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2239    command called pgrep for grepping around the active processes.
2241    7. Added the beginnings of support for UTF-8 character strings.
2243    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2244    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2245    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2246    out for the ar command.)
2249    Version 3.2 12-May-00
2250    ---------------------
2252    This is purely a bug fixing release.
2254    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2255    of ZA. This was just one example of several cases that could provoke this bug,
2256    which was introduced by change 9 of version 2.00. The code for breaking
2257    infinite loops after an iteration that matches an empty string was't working
2258    correctly.
2260    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2261    when matched against abbab (for example). After matching an empty string, it
2262    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2263    caused it to match further down the string than it should.
2265    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2266    was there because it doesn't seem to be needed, and it causes trouble on some
2267    systems, as it is not a Standard C header. It has been removed.
2269    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2270    were reported on the Macintosh. The changes were from
2272      while ((c = *(++ptr)) != 0 && c != '\n');
2273    to
2274      while ((c = *(++ptr)) != 0 && c != '\n') ;
2276    Totally extraordinary, but if that's what it takes...
2278    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2279    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2280    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2281    assumes the way PCRE uses memmove() (always moving upwards).
2283    6. PCRE is being used in one environment where strchr() is not available. There
2284    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2285    faster code anyway.
2288    Version 3.1 09-Feb-00
2289    ---------------------
2291    The only change in this release is the fixing of some bugs in Makefile.in for
2292    the "install" target:
2294    (1) It was failing to install pcreposix.h.
2296    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2299    Version 3.0 01-Feb-00
2300    ---------------------
2302    1. Add support for the /+ modifier to perltest (to output $` like it does in
2303    pcretest).
2305    2. Add support for the /g modifier to perltest.
2307    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2308    matches null strings.
2310    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2311    pattern. Perl treats empty patterns specially - it reuses the most recent
2312    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2313    effect.
2315    5. The POSIX interface was broken in that it was just handing over the POSIX
2316    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2317    required a bigger vector, with some working space on the end. This means that
2318    the POSIX wrapper now has to get and free some memory, and copy the results.
2320    6. Added some simple autoconf support, placing the test data and the
2321    documentation in separate directories, re-organizing some of the
2322    information files, and making it build pcre-config (a GNU standard). Also added
2323    libtool support for building PCRE as a shared library, which is now the
2324    default.
2326    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2327    09 are not valid octal constants. Single digits will be used for minor values
2328    less than 10.
2330    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2331    existing programs that set these in the POSIX interface can use PCRE without
2332    modification.
2334    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2335    return all that pcre_info() returns, plus additional data. The pcre_info()
2336    function is retained for compatibility, but is considered to be obsolete.
2338    10. Added experimental recursion feature (?R) to handle one common case that
2339    Perl 5.6 will be able to do with (?p{...}).
2341    11. Added support for POSIX character classes like [:alpha:], which Perl is
2342    adopting.
2345    Version 2.08 31-Aug-99
2346    ----------------------
2348    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2349    trying to match at the startoffset position, but instead was moving forward to
2350    the next newline as if a previous match had failed.
2352    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2353    and could get into a loop if a null string was matched other than at the start
2354    of the subject.
2356    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2357    be distinguished at compile time, and for completeness also added PCRE_DATE.
2359    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2360    in GnuWin32 environments.
2363    Version 2.07 29-Jul-99
2364    ----------------------
2366    1. The documentation is now supplied in plain text form and HTML as well as in
2367    the form of man page sources.
2369    2. C++ compilers don't like assigning (void *) values to other pointer types.
2370    In particular this affects malloc(). Although there is no problem in Standard
2371    C, I've put in casts to keep C++ compilers happy.
2373    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2374    should be (const char *).
2376    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2377    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2378    However, I haven't made this a standard facility. The documentation doesn't
2379    mention it, and the Makefile doesn't support it.
2381    5. The Makefile now contains an "install" target, with editable destinations at
2382    the top of the file. The pcretest program is not installed.
2384    6. pgrep -V now gives the PCRE version number and date.
2386    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2387    causing the entire string to be ignored, instead of just the last character.
2389    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2390    non-matching string, it can take a very, very long time, even for strings of
2391    quite modest length, because of the nested recursion. PCRE now does better in
2392    some of these cases. It does this by remembering the last required literal
2393    character in the pattern, and pre-searching the subject to ensure it is present
2394    before running the real match. In other words, it applies a heuristic to detect
2395    some types of certain failure quickly, and in the above example, if presented
2396    with a string that has no trailing " it gives "no match" very quickly.
2398    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2399    other alternatives are tried instead.
2402    Version 2.06 09-Jun-99
2403    ----------------------
2405    1. Change pcretest's output for amount of store used to show just the code
2406    space, because the remainder (the data block) varies in size between 32-bit and
2407    64-bit systems.
2409    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2410    start matching at. This allows lookbehinds to work when searching for multiple
2411    occurrences in a string.
2413    3. Added additional options to pcretest for testing multiple occurrences:
2415       /+   outputs the rest of the string that follows a match
2416       /g   loops for multiple occurrences, using the new startoffset argument
2417       /G   loops for multiple occurrences by passing an incremented pointer
2419    4. PCRE wasn't doing the "first character" optimization for patterns starting
2420    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2421    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2422    the letter 'x'. On long subject strings, this gives a significant speed-up.
2425    Version 2.05 21-Apr-99
2426    ----------------------
2428    1. Changed the type of magic_number from int to long int so that it works
2429    properly on 16-bit systems.
2431    2. Fixed a bug which caused patterns starting with .* not to work correctly
2432    when the subject string contained newline characters. PCRE was assuming
2433    anchoring for such patterns in all cases, which is not correct because .* will
2434    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2435    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2436    must be retried after every newline in the subject.
2439    Version 2.04 18-Feb-99
2440    ----------------------
2442    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2443    computation of the store needed to hold the pattern was incorrect (too large).
2444    If such patterns were nested a few deep, this could multiply and become a real
2445    problem.
2447    2. Added /M option to pcretest to show the memory requirement of a specific
2448    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2450    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2451    compiled in such a way that the backtracking after subsequent failure was
2452    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2453    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2456    Version 2.03 02-Feb-99
2457    ----------------------
2459    1. Fixed typo and small mistake in man page.
2461    2. Added 4th condition (GPL supersedes if conflict) and created separate
2462    LICENCE file containing the conditions.
2464    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2465    Perl, that is the internal \ allows the delimiter to be included in the
2466    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2467    the final delimiter, add \ to the end of the pattern (to test the error).
2469    4. Added the convenience functions for extracting substrings after a successful
2470    match. Updated pcretest to make it able to test these functions.
2473    Version 2.02 14-Jan-99
2474    ----------------------
2476    1. Initialized the working variables associated with each extraction so that
2477    their saving and restoring doesn't refer to uninitialized store.
2479    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2480    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2481    fix the problem.
2483    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2484    calls, and wasn't printing the correct value for compiling calls. Increased the
2485    default value of LOOPREPEAT, and the number of significant figures in the
2486    times.
2488    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2490    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2491    a building problem on Windows NT with a FAT file system.
2494    Version 2.01 21-Oct-98
2495    ----------------------
2497    1. Changed the API for pcre_compile() to allow for the provision of a pointer
2498    to character tables built by pcre_maketables() in the current locale. If NULL
2499    is passed, the default tables are used.
2502    Version 2.00 24-Sep-98
2503    ----------------------
2505    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2506    it any more.
2508    2. Allow quantification of (?>) groups, and make it work correctly.
2510    3. The first character computation wasn't working for (?>) groups.
2512    4. Correct the implementation of \Z (it is permitted to match on the \n at the
2513    end of the subject) and add 5.005's \z, which really does match only at the
2514    very end of the subject.
2516    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2518    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2519    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2520    localized options. All options to pcre_study() were also removed.
2522    7. Add other new features from 5.005:
2524       $(?<=           positive lookbehind
2525       $(?<!           negative lookbehind
2526       (?imsx-imsx)    added the unsetting capability
2527                       such a setting is global if at outer level; local otherwise
2528       (?imsx-imsx:)   non-capturing groups with option setting
2529       (?(cond)re|re)  conditional pattern matching
2531       A backreference to itself in a repeated group matches the previous
2532       captured string.
2534    8. General tidying up of studying (both automatic and via "study")
2535    consequential on the addition of new assertions.
2537    9. As in 5.005, unlimited repeated groups that could match an empty substring
2538    are no longer faulted at compile time. Instead, the loop is forcibly broken at
2539    runtime if any iteration does actually match an empty substring.
2541    10. Include the RunTest script in the distribution.
2543    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2544    discrepancies, some of which were old and were also with respect to 5.004. They
2545    have now been fixed.
2548    Version 1.09 28-Apr-98
2549    ----------------------
2551    1. A negated single character class followed by a quantifier with a minimum
2552    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
2553    program crashes, or just wrong answers. This did not apply to negated classes
2554    containing more than one character, or to minima other than one.
2557    Version 1.08 27-Mar-98
2558    ----------------------
2560    1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
2562    2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
2563    latter must appear before anything that relies on it in the pattern.
2566    Version 1.07 16-Feb-98
2567    ----------------------
2569    1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
2570    repeat of a potentially empty string).
2573  Version 1.06 23-Jan-98  Version 1.06 23-Jan-98
2574  ----------------------  ----------------------

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