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revision 51 by nigel, Sat Feb 24 21:39:37 2007 UTC revision 276 by ph10, Wed Nov 21 15:39:20 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.5 12-Nov-07
5    ---------------------
7    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
8        values in parens when parsing an RE using the C++ wrapper."
10    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
11        Characters greater than 255 were excluded from the class instead of being
12        included.
14    3.  The same bug as (2) above applied to negated POSIX classes such as
15        [:^space:].
17    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
18        defined or documented. It seems to have been a typo for PCRE_STATIC, so
19        I have changed it.
21    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
22        first named subpattern) and a construct such as (?&a) would reference the
23        first named subpattern whose name started with "a" (in other words, the
24        length check was missing). Both these problems are fixed. "Subpattern name
25        expected" is now given for (?&) (a zero-length name), and this patch also
26        makes it give the same error for \k'' (previously it complained that that
27        was a reference to a non-existent subpattern).
29    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
30        this is right because (?- can be followed by option settings as well as by
31        digits. I have, however, made the messages clearer.
33    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
34        than the number used in the conditional) now cause a compile-time error.
35        This is actually not compatible with Perl, which accepts such patterns, but
36        treats the conditional as always being FALSE (as PCRE used to), but it
37        seems to me that giving a diagnostic is better.
39    8.  Change "alphameric" to the more common word "alphanumeric" in comments
40        and messages.
42    9.  Fix two occurrences of "backslash" in comments that should have been
43        "backspace".
45    10. Remove two redundant lines of code that can never be obeyed (their function
46        was moved elsewhere).
49    Version 7.4 21-Sep-07
50    ---------------------
52    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
53        means that a class such as [\s] counted as "explicit reference to CR or
54        LF". That isn't really right - the whole point of the change was to try to
55        help when there was an actual mention of one of the two characters. So now
56        the change happens only if \r or \n (or a literal CR or LF) character is
57        encountered.
59    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
60        of both had grown to the point where there were only 3 bits left.
61        Fortunately, there was spare space in the data structure, and so I have
62        moved the internal flags into a new 16-bit field to free up more option
63        bits.
65    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
66        but did not set the internal JCHANGED flag - either of these is enough to
67        control the way the "get" function works - but the PCRE_INFO_JCHANGED
68        facility is supposed to tell if (?J) was ever used, so now (?J) at the
69        start sets both bits.
71    4.  Added options (at build time, compile time, exec time) to change \R from
72        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
74    5.  doc/pcresyntax.html was missing from the distribution.
76    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
77        compatibility, even though it is no longer used.
79    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
80        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
81        windows.h file is present (where different names are used). [This was
82        reversed later after testing - see 16 below.]
84    8.  Changed all #include <config.h> to #include "config.h". There were also
85        some further <pcre.h> cases that I changed to "pcre.h".
87    9.  When pcregrep was used with the --colour option, it missed the line ending
88        sequence off the lines that it output.
90    10. It was pointed out to me that arrays of string pointers cause lots of
91        relocations when a shared library is dynamically loaded. A technique of
92        using a single long string with a table of offsets can drastically reduce
93        these. I have refactored PCRE in four places to do this. The result is
94        dramatic:
96          Originally:                          290
97          After changing UCP table:            187
98          After changing error message table:   43
99          After changing table of "verbs"       36
100          After changing table of Posix names   22
102        Thanks to the folks working on Gregex for glib for this insight.
104    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
105        unicode-properties was also set.
107    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
109    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
110        checked only for CRLF.
112    14. Added casts to pcretest.c to avoid compiler warnings.
114    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
116    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
117        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
118        entirely. This removes changes made in 7 above.
120    17. The CMake files have been updated, and there is now more information about
121        building with CMake in the NON-UNIX-USE document.
124    Version 7.3 28-Aug-07
125    ---------------------
127     1. In the rejigging of the build system that eventually resulted in 7.1, the
128        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
129        brackets there is not right, since it causes compilers to look for an
130        installed pcre.h, not the version that is in the source that is being
131        compiled (which of course may be different). I have changed it back to:
133          #include "pcre.h"
135        I have a vague recollection that the change was concerned with compiling in
136        different directories, but in the new build system, that is taken care of
137        by the VPATH setting the Makefile.
139     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
140        when the subject happened to end in the byte 0x85 (e.g. if the last
141        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
142        characters but of course it shouldn't be taken as a newline when it is part
143        of another character. The bug was that, for an unlimited repeat of . in
144        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
145        characters when looking for a newline.
147     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
149     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
150        in debug output.
152     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
153        long printing in the pcrecpp unittest when running under MinGW.
155     6. ESC_K was left out of the EBCDIC table.
157     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
158        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
159        limit also applies to "virtual nesting" when a pattern is recursive, and in
160        this case 1000 isn't so big. I have been able to remove this limit at the
161        expense of backing off one optimization in certain circumstances. Normally,
162        when pcre_exec() would call its internal match() function recursively and
163        immediately return the result unconditionally, it uses a "tail recursion"
164        feature to save stack. However, when a subpattern that can match an empty
165        string has an unlimited repetition quantifier, it no longer makes this
166        optimization. That gives it a stack frame in which to save the data for
167        checking that an empty string has been matched. Previously this was taken
168        from the 1000-entry workspace that had been reserved. So now there is no
169        explicit limit, but more stack is used.
171     8. Applied Daniel's patches to solve problems with the import/export magic
172        syntax that is required for Windows, and which was going wrong for the
173        pcreposix and pcrecpp parts of the library. These were overlooked when this
174        problem was solved for the main library.
176     9. There were some crude static tests to avoid integer overflow when computing
177        the size of patterns that contain repeated groups with explicit upper
178        limits. As the maximum quantifier is 65535, the maximum group length was
179        set at 30,000 so that the product of these two numbers did not overflow a
180        32-bit integer. However, it turns out that people want to use groups that
181        are longer than 30,000 bytes (though not repeat them that many times).
182        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
183        made it possible to implement the integer overflow checks in a much more
184        dynamic way, which I have now done. The artificial limitation on group
185        length has been removed - we now have only the limit on the total length of
186        the compiled pattern, which depends on the LINK_SIZE setting.
188    10. Fixed a bug in the documentation for get/copy named substring when
189        duplicate names are permitted. If none of the named substrings are set, the
190        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
191        empty string.
193    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
194        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
195        because the ] is interpreted as the first data character and the
196        terminating ] is not found. PCRE has been made compatible with Perl in this
197        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
198        cause memory overwriting.
200    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
201        string has been matched (to stop an infinite loop). It was not recognizing
202        a conditional subpattern that could match an empty string if that
203        subpattern was within another subpattern. For example, it looped when
204        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
205        condition was not nested. This bug has been fixed.
207    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
208        past the start of the subject in the presence of bytes with the top bit
209        set, for example "\x8aBCD".
211    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
212        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
214    14. Optimized (?!) to (*FAIL).
216    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
217        This restricts code points to be within the range 0 to 0x10FFFF, excluding
218        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
219        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
220        does: it's just the validity check that is more restrictive.
222    16. Inserted checks for integer overflows during escape sequence (backslash)
223        processing, and also fixed erroneous offset values for syntax errors during
224        backslash processing.
226    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
227        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
229    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
230        caused an overrun.
232    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
233        something other than just ASCII characters) inside a group that had an
234        unlimited repeat caused a loop at compile time (while checking to see
235        whether the group could match an empty string).
237    20. Debugging a pattern containing \p or \P could cause a crash. For example,
238        [\P{Any}] did so. (Error in the code for printing property names.)
240    21. An orphan \E inside a character class could cause a crash.
242    22. A repeated capturing bracket such as (A)? could cause a wild memory
243        reference during compilation.
245    23. There are several functions in pcre_compile() that scan along a compiled
246        expression for various reasons (e.g. to see if it's fixed length for look
247        behind). There were bugs in these functions when a repeated \p or \P was
248        present in the pattern. These operators have additional parameters compared
249        with \d, etc, and these were not being taken into account when moving along
250        the compiled data. Specifically:
252        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
253            length.
255        (b) An item such as \pL+ within a repeated group could cause crashes or
256            loops.
258        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
259            "reference to non-existent subpattern" error.
261        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
263    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
264        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
266    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
268    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
269        character were causing crashes (broken optimization).
271    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
272        \p or \P) caused a compile-time loop.
274    28. More problems have arisen in unanchored patterns when CRLF is a valid line
275        break. For example, the unstudied pattern [\r\n]A does not match the string
276        "\r\nA" because change 7.0/46 below moves the current point on by two
277        characters after failing to match at the start. However, the pattern \nA
278        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
279        the same is true. There doesn't seem any very clean way out of this, but
280        what I have chosen to do makes the common cases work: PCRE now takes note
281        of whether there can be an explicit match for \r or \n anywhere in the
282        pattern, and if so, 7.0/46 no longer applies. As part of this change,
283        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
284        pattern has explicit CR or LF references.
286    29. Added (*CR) etc for changing newline setting at start of pattern.
289    Version 7.2 19-Jun-07
290    ---------------------
292     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
293        which is apparently normally available under Windows.
295     2. Re-jig the pcregrep tests with different newline settings in an attempt
296        to make them independent of the local environment's newline setting.
298     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
300     4. Some of the "internals" tests were previously cut out when the link size
301        was not 2, because the output contained actual offsets. The recent new
302        "Z" feature of pcretest means that these can be cut out, making the tests
303        usable with all link sizes.
305     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
306        stack recursion. This gives a massive performance boost under BSD, but just
307        a small improvement under Linux. However, it saves one field in the frame
308        in all cases.
310     6. Added more features from the forthcoming Perl 5.10:
312        (a) (?-n) (where n is a string of digits) is a relative subroutine or
313            recursion call. It refers to the nth most recently opened parentheses.
315        (b) (?+n) is also a relative subroutine call; it refers to the nth next
316            to be opened parentheses.
318        (c) Conditions that refer to capturing parentheses can be specified
319            relatively, for example, (?(-2)... or (?(+3)...
321        (d) \K resets the start of the current match so that everything before
322            is not part of it.
324        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
326        (f) \g{name} is another synonym - part of Perl 5.10's unification of
327            reference syntax.
329        (g) (?| introduces a group in which the numbering of parentheses in each
330            alternative starts with the same number.
332        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
334     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
337     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
338        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
339        for detecting groups that can match an empty string.
341     9. A pattern with a very large number of alternatives (more than several
342        hundred) was running out of internal workspace during the pre-compile
343        phase, where pcre_compile() figures out how much memory will be needed. A
344        bit of new cunning has reduced the workspace needed for groups with
345        alternatives. The 1000-alternative test pattern now uses 12 bytes of
346        workspace instead of running out of the 4096 that are available.
348    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
350    11. Applied patch from Google to remove an optimization that didn't quite work.
351        The report of the bug said:
353          pcrecpp::RE("a*").FullMatch("aaa") matches, while
354          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
355          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
357    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
358        it matched the wrong number of bytes.
361    Version 7.1 24-Apr-07
362    ---------------------
364     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
365        that is more "standard", making use of automake and other Autotools. There
366        is some re-arrangement of the files and adjustment of comments consequent
367        on this.
369     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
370        for recursive directory scanning broke on some systems because the files
371        are not scanned in any specific order and on different systems the order
372        was different. A call to "sort" has been inserted into RunGrepTest for the
373        approprate test as a short-term fix. In the longer term there may be an
374        alternative.
376     3. I had an email from Eric Raymond about problems translating some of PCRE's
377        man pages to HTML (despite the fact that I distribute HTML pages, some
378        people do their own conversions for various reasons). The problems
379        concerned the use of low-level troff macros .br and .in. I have therefore
380        removed all such uses from the man pages (some were redundant, some could
381        be replaced by .nf/.fi pairs). The 132html script that I use to generate
382        HTML has been updated to handle .nf/.fi and to complain if it encounters
383        .br or .in.
385     4. Updated comments in configure.ac that get placed in config.h.in and also
386        arranged for config.h to be included in the distribution, with the name
387        config.h.generic, for the benefit of those who have to compile without
388        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
390     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
391        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
392        makevp.bat for the current PCRE, using the additional files
393        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
395     6. A Windows user reported a minor discrepancy with test 2, which turned out
396        to be caused by a trailing space on an input line that had got lost in his
397        copy. The trailing space was an accident, so I've just removed it.
399     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
400        that is needed.
402     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
403        as "const" (a) because they are and (b) because it helps the PHP
404        maintainers who have recently made a script to detect big data structures
405        in the php code that should be moved to the .rodata section. I remembered
406        to update Builducptable as well, so it won't revert if ucptable.h is ever
407        re-created.
409     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
410        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
411        order to be able to cut out the UTF-8 tables in the latter when UTF-8
412        support is not required. This saves 1.5-2K of code, which is important in
413        some applications.
415        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
416        so as not to refer to the tables, even though these functions will never be
417        called when UTF-8 support is disabled. Otherwise there are problems with a
418        shared library.
420    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
422        (a) It was defining its arguments as char * instead of void *.
424        (b) It was assuming that all moves were upwards in memory; this was true
425            a long time ago when I wrote it, but is no longer the case.
427        The emulated memove() is provided for those environments that have neither
428        memmove() nor bcopy(). I didn't think anyone used it these days, but that
429        is clearly not the case, as these two bugs were recently reported.
431    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
432        and Detrail to create the HTML documentation, the .txt form of the man
433        pages, and it removes trailing spaces from listed files. It also creates
434        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
435        case, it wraps all the #defines with #ifndefs. This script should be run
436        before "make dist".
438    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
439        with Unicode property support.
441        (a) For a maximizing quantifier, if the two different cases of the
442            character were of different lengths in their UTF-8 codings (there are
443            some cases like this - I found 11), and the matching function had to
444            back up over a mixture of the two cases, it incorrectly assumed they
445            were both the same length.
447        (b) When PCRE was configured to use the heap rather than the stack for
448            recursion during matching, it was not correctly preserving the data for
449            the other case of a UTF-8 character when checking ahead for a match
450            while processing a minimizing repeat. If the check also involved
451            matching a wide character, but failed, corruption could cause an
452            erroneous result when trying to check for a repeat of the original
453            character.
455    13. Some tidying changes to the testing mechanism:
457        (a) The RunTest script now detects the internal link size and whether there
458            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
459            values substituted by "configure". (The RunGrepTest script already did
460            this for UTF-8.) The configure.ac script no longer substitutes the
461            relevant variables.
463        (b) The debugging options /B and /D in pcretest show the compiled bytecode
464            with length and offset values. This means that the output is different
465            for different internal link sizes. Test 2 is skipped for link sizes
466            other than 2 because of this, bypassing the problem. Unfortunately,
467            there was also a test in test 3 (the locale tests) that used /B and
468            failed for link sizes other than 2. Rather than cut the whole test out,
469            I have added a new /Z option to pcretest that replaces the length and
470            offset values with spaces. This is now used to make test 3 independent
471            of link size. (Test 2 will be tidied up later.)
473    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
474        segmentation fault instead of returning the appropriate error message.
476    15. In multiline mode when the newline sequence was set to "any", the pattern
477        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
478        This doesn't seem right; it now treats the CRLF combination as the line
479        ending, and so does not match in that case. It's only a pattern such as ^$
480        that would hit this one: something like ^ABC$ would have failed after \r
481        and then tried again after \r\n.
483    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
484        in an attempt to make files that differ only in their line terminators
485        compare equal. This works on Linux.
487    17. Under certain error circumstances pcregrep might try to free random memory
488        as it exited. This is now fixed, thanks to valgrind.
490    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
491        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
492        was because its rules for how to advance for /g after matching an empty
493        string at the end of a line did not allow for this case. They now check for
494        it specially.
496    20. pcretest is supposed to handle patterns and data of any length, by
497        extending its buffers when necessary. It was getting this wrong when the
498        buffer for a data line had to be extended.
500    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
501        CRLF as a newline sequence.
503    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
504        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
505        I have nevertheless tidied it up.
507    23. Added some casts to kill warnings from HP-UX ia64 compiler.
509    24. Added a man page for pcre-config.
512    Version 7.0 19-Dec-06
513    ---------------------
515     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
516        moving to gcc 4.1.1.
518     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
519        sys/time.h, which is documented as needed for this function. It doesn't
520        seem to matter on Linux, but it showed up on some releases of OS X.
522     3. It seems that there are systems where bytes whose values are greater than
523        127 match isprint() in the "C" locale. The "C" locale should be the
524        default when a C program starts up. In most systems, only ASCII printing
525        characters match isprint(). This difference caused the output from pcretest
526        to vary, making some of the tests fail. I have changed pcretest so that:
528        (a) When it is outputting text in the compiled version of a pattern, bytes
529            other than 32-126 are always shown as hex escapes.
531        (b) When it is outputting text that is a matched part of a subject string,
532            it does the same, unless a different locale has been set for the match
533            (using the /L modifier). In this case, it uses isprint() to decide.
535     4. Fixed a major bug that caused incorrect computation of the amount of memory
536        required for a compiled pattern when options that changed within the
537        pattern affected the logic of the preliminary scan that determines the
538        length. The relevant options are -x, and -i in UTF-8 mode. The result was
539        that the computed length was too small. The symptoms of this bug were
540        either the PCRE error "internal error: code overflow" from pcre_compile(),
541        or a glibc crash with a message such as "pcretest: free(): invalid next
542        size (fast)". Examples of patterns that provoked this bug (shown in
543        pcretest format) are:
545          /(?-x: )/x
546          /(?x)(?-x: \s*#\s*)/
547          /((?i)[\x{c0}])/8
548          /(?i:[\x{c0}])/8
550        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
551        is now done differently.
553     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
554        wrapper classes; (b) implement a new function in the C++ scanner that is
555        more efficient than the old way of doing things because it avoids levels of
556        recursion in the regex matching; (c) add a paragraph to the documentation
557        for the FullMatch() function.
559     6. The escape sequence \n was being treated as whatever was defined as
560        "newline". Not only was this contrary to the documentation, which states
561        that \n is character 10 (hex 0A), but it also went horribly wrong when
562        "newline" was defined as CRLF. This has been fixed.
564     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
565        was being set to -1 for the "end of line" case (supposedly a value that no
566        character can have). Though this value is never used (the check for end of
567        line is "zero bytes in current character"), it caused compiler complaints.
568        I've changed it to 0xffffffff.
570     8. In pcre_version.c, the version string was being built by a sequence of
571        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
572        string (as it is for production releases) called a macro with an empty
573        argument. The C standard says the result of this is undefined. The gcc
574        compiler treats it as an empty string (which was what was wanted) but it is
575        reported that Visual C gives an error. The source has been hacked around to
576        avoid this problem.
578     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
579        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
580        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
581        of them did).
583    10. Originally, pcretest opened its input and output without "b"; then I was
584        told that "b" was needed in some environments, so it was added for release
585        5.0 to both the input and output. (It makes no difference on Unix-like
586        systems.) Later I was told that it is wrong for the input on Windows. I've
587        now abstracted the modes into two macros, to make it easier to fiddle with
588        them, and removed "b" from the input mode under Windows.
590    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
592    12. Added -help and --help to pcretest as an official way of being reminded
593        of the options.
595    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
596        and pcrecpp.cc because they annoy compilers at high warning levels.
598    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
600    15. Fixed an occurrence of == in configure.ac that should have been = (shell
601        scripts are not C programs :-) and which was not noticed because it works
602        on Linux.
604    16. pcretest is supposed to handle any length of pattern and data line (as one
605        line or as a continued sequence of lines) by extending its input buffer if
606        necessary. This feature was broken for very long pattern lines, leading to
607        a string of junk being passed to pcre_compile() if the pattern was longer
608        than about 50K.
610    17. I have done a major re-factoring of the way pcre_compile() computes the
611        amount of memory needed for a compiled pattern. Previously, there was code
612        that made a preliminary scan of the pattern in order to do this. That was
613        OK when PCRE was new, but as the facilities have expanded, it has become
614        harder and harder to keep it in step with the real compile phase, and there
615        have been a number of bugs (see for example, 4 above). I have now found a
616        cunning way of running the real compile function in a "fake" mode that
617        enables it to compute how much memory it would need, while actually only
618        ever using a few hundred bytes of working memory and without too many
619        tests of the mode. This should make future maintenance and development
620        easier. A side effect of this work is that the limit of 200 on the nesting
621        depth of parentheses has been removed (though this was never a serious
622        limitation, I suspect). However, there is a downside: pcre_compile() now
623        runs more slowly than before (30% or more, depending on the pattern). I
624        hope this isn't a big issue. There is no effect on runtime performance.
626    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
627        newline (only possible for the last line of a file) and it was a
628        pattern that set a locale (followed by /Lsomething), pcretest crashed.
630    19. Added additional timing features to pcretest. (1) The -tm option now times
631        matching only, not compiling. (2) Both -t and -tm can be followed, as a
632        separate command line item, by a number that specifies the number of
633        repeats to use when timing. The default is 50000; this gives better
634        precision, but takes uncomfortably long for very large patterns.
636    20. Extended pcre_study() to be more clever in cases where a branch of a
637        subpattern has no definite first character. For example, (a*|b*)[cd] would
638        previously give no result from pcre_study(). Now it recognizes that the
639        first character must be a, b, c, or d.
641    21. There was an incorrect error "recursive call could loop indefinitely" if
642        a subpattern (or the entire pattern) that was being tested for matching an
643        empty string contained only one non-empty item after a nested subpattern.
644        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
645        incorrectly, because the \d was being skipped in the check.
647    22. The pcretest program now has a new pattern option /B and a command line
648        option -b, which is equivalent to adding /B to every pattern. This causes
649        it to show the compiled bytecode, without the additional information that
650        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
651        is the same as /B/I).
653    23. A new optimization is now able automatically to treat some sequences such
654        as a*b as a*+b. More specifically, if something simple (such as a character
655        or a simple class like \d) has an unlimited quantifier, and is followed by
656        something that cannot possibly match the quantified thing, the quantifier
657        is automatically "possessified".
659    24. A recursive reference to a subpattern whose number was greater than 39
660        went wrong under certain circumstances in UTF-8 mode. This bug could also
661        have affected the operation of pcre_study().
663    25. Realized that a little bit of performance could be had by replacing
664        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
666    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
668    27. Possessive quantifiers such as a++ were previously implemented by turning
669        them into atomic groups such as ($>a+). Now they have their own opcodes,
670        which improves performance. This includes the automatically created ones
671        from 23 above.
673    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
674        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
675        the first matched character to be a colon. This applied both to named and
676        numbered groups.
678    29. The ucpinternal.h header file was missing its idempotency #ifdef.
680    30. I was sent a "project" file called libpcre.a.dev which I understand makes
681        building PCRE on Windows easier, so I have included it in the distribution.
683    31. There is now a check in pcretest against a ridiculously large number being
684        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
685        loop, the loop is abandoned.
687    32. Forward references to subpatterns in conditions such as (?(2)...) where
688        subpattern 2 is defined later cause pcre_compile() to search forwards in
689        the pattern for the relevant set of parentheses. This search went wrong
690        when there were unescaped parentheses in a character class, parentheses
691        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
693    33. "Subroutine" calls and backreferences were previously restricted to
694        referencing subpatterns earlier in the regex. This restriction has now
695        been removed.
697    34. Added a number of extra features that are going to be in Perl 5.10. On the
698        whole, these are just syntactic alternatives for features that PCRE had
699        previously implemented using the Python syntax or my own invention. The
700        other formats are all retained for compatibility.
702        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
703            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
704            also .NET compatible.
706        (b) A recursion or subroutine call to a named group can now be defined as
707            (?&name) as well as (?P>name).
709        (c) A backreference to a named group can now be defined as \k<name> or
710            \k'name' as well as (?P=name). The new forms, as well as being in Perl
711            5.10, are also .NET compatible.
713        (d) A conditional reference to a named group can now use the syntax
714            (?(<name>) or (?('name') as well as (?(name).
716        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
717            groups (named and numbered) that are never evaluated inline, but can be
718            called as "subroutines" from elsewhere. In effect, the DEFINE condition
719            is always false. There may be only one alternative in such a group.
721        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
722            as the simple (?(R). The condition is true only if the most recent
723            recursion is that of the given number or name. It does not search out
724            through the entire recursion stack.
726        (g) The escape \gN or \g{N} has been added, where N is a positive or
727            negative number, specifying an absolute or relative reference.
729    35. Tidied to get rid of some further signed/unsigned compiler warnings and
730        some "unreachable code" warnings.
732    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
733        things, this adds five new scripts.
735    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
736        There were also incompatibilities regarding the handling of \Q..\E inside
737        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
738        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
740    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
741        matches an empty string, and forcibly breaks the loop. There were bugs in
742        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
743        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
744        separate and independent bugs (that affected different cases) have been
745        fixed.
747    39. Refactored the code to abolish the use of different opcodes for small
748        capturing bracket numbers. This is a tidy that I avoided doing when I
749        removed the limit on the number of capturing brackets for 3.5 back in 2001.
750        The new approach is not only tidier, it makes it possible to reduce the
751        memory needed to fix the previous bug (38).
753    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
754        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
755        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
756        mode.
758    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
759        report.
761    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
762        copy construction and assignment in the C++ wrapper.
764    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
765        couple of bugs that could have given wrong results in the "--newline=crlf"
766        case.
768    44. Added a number of casts and did some reorganization of signed/unsigned int
769        variables following suggestions from Dair Grant. Also renamed the variable
770        "this" as "item" because it is a C++ keyword.
772    45. Arranged for dftables to add
774          #include "pcre_internal.h"
776        to pcre_chartables.c because without it, gcc 4.x may remove the array
777        definition from the final binary if PCRE is built into a static library and
778        dead code stripping is activated.
780    46. For an unanchored pattern, if a match attempt fails at the start of a
781        newline sequence, and the newline setting is CRLF or ANY, and the next two
782        characters are CRLF, advance by two characters instead of one.
785    Version 6.7 04-Jul-06
786    ---------------------
788     1. In order to handle tests when input lines are enormously long, pcretest has
789        been re-factored so that it automatically extends its buffers when
790        necessary. The code is crude, but this _is_ just a test program. The
791        default size has been increased from 32K to 50K.
793     2. The code in pcre_study() was using the value of the re argument before
794        testing it for NULL. (Of course, in any sensible call of the function, it
795        won't be NULL.)
797     3. The memmove() emulation function in pcre_internal.h, which is used on
798        systems that lack both memmove() and bcopy() - that is, hardly ever -
799        was missing a "static" storage class specifier.
801     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
802        containing an extended class (one that cannot be represented by a bitmap
803        because it contains high-valued characters or Unicode property items, e.g.
804        [\pZ]). Almost always one would set UTF-8 mode when processing such a
805        pattern, but PCRE should not loop if you do not (it no longer does).
806        [Detail: two cases were found: (a) a repeated subpattern containing an
807        extended class; (b) a recursive reference to a subpattern that followed a
808        previous extended class. It wasn't skipping over the extended class
809        correctly when UTF-8 mode was not set.]
811     5. A negated single-character class was not being recognized as fixed-length
812        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
813        compile error "lookbehind assertion is not fixed length".
815     6. The RunPerlTest auxiliary script was showing an unexpected difference
816        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
817        write a Perl script that can interpret lines of an input file either as
818        byte characters or as UTF-8, which is what "perltest" was being required to
819        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
820        can't do is switch easily at run time between having the "use utf8;" pragma
821        or not. In the end, I fudged it by using the RunPerlTest script to insert
822        "use utf8;" explicitly for the UTF-8 tests.
824     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
825        the end of the subject string, contrary to the documentation and to what
826        Perl does. This was true of both matching functions. Now it matches only at
827        the start of the subject and immediately after *internal* newlines.
829     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
830        a pointer to an int instead of a pointer to an unsigned long int. This
831        caused problems on 64-bit systems.
833     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
834        instance of the 'standard' template library not being so standard".
836    10. There was no check on the number of named subpatterns nor the maximum
837        length of a subpattern name. The product of these values is used to compute
838        the size of the memory block for a compiled pattern. By supplying a very
839        long subpattern name and a large number of named subpatterns, the size
840        computation could be caused to overflow. This is now prevented by limiting
841        the length of names to 32 characters, and the number of named subpatterns
842        to 10,000.
844    11. Subpatterns that are repeated with specific counts have to be replicated in
845        the compiled pattern. The size of memory for this was computed from the
846        length of the subpattern and the repeat count. The latter is limited to
847        65535, but there was no limit on the former, meaning that integer overflow
848        could in principle occur. The compiled length of a repeated subpattern is
849        now limited to 30,000 bytes in order to prevent this.
851    12. Added the optional facility to have named substrings with the same name.
853    13. Added the ability to use a named substring as a condition, using the
854        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
855        are numbers (not recommended). Forward references are permitted.
857    14. Added forward references in named backreferences (if you see what I mean).
859    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
860        pattern could run off the end of the subject. For example, the pattern
861        "(?s)(.{1,5})"8 did this with the subject "ab".
863    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
864        PCRE_CASELESS was set when matching characters that were quantified with ?
865        or *.
867    17. A character class other than a single negated character that had a minimum
868        but no maximum quantifier - for example [ab]{6,} - was not handled
869        correctly by pce_dfa_exec(). It would match only one character.
871    18. A valid (though odd) pattern that looked like a POSIX character
872        class but used an invalid character after [ (for example [[,abc,]]) caused
873        pcre_compile() to give the error "Failed: internal error: code overflow" or
874        in some cases to crash with a glibc free() error. This could even happen if
875        the pattern terminated after [[ but there just happened to be a sequence of
876        letters, a binary zero, and a closing ] in the memory that followed.
878    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
879        over the years. Originally (before any Unicode support), just the bottom 8
880        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
881        output from "man perlunicode" includes this:
883          The regular expression compiler produces polymorphic opcodes.  That
884          is, the pattern adapts to the data and automatically switches to
885          the Unicode character scheme when presented with Unicode data--or
886          instead uses a traditional byte scheme when presented with byte
887          data.
889        Sadly, a wide octal escape does not cause a switch, and in a string with
890        no other multibyte characters, these octal escapes are treated as before.
891        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
892        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
893        Unicode string.
895        I have not perpetrated such confusion in PCRE. Up till now, it took just
896        the bottom 8 bits, as in old Perl. I have now made octal escapes with
897        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
898        translate to the appropriate multibyte character.
900    29. Applied some refactoring to reduce the number of warnings from Microsoft
901        and Borland compilers. This has included removing the fudge introduced
902        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
903        a warning about an unused variable.
905    21. PCRE has not included VT (character 0x0b) in the set of whitespace
906        characters since release 4.0, because Perl (from release 5.004) does not.
907        [Or at least, is documented not to: some releases seem to be in conflict
908        with the documentation.] However, when a pattern was studied with
909        pcre_study() and all its branches started with \s, PCRE still included VT
910        as a possible starting character. Of course, this did no harm; it just
911        caused an unnecessary match attempt.
913    22. Removed a now-redundant internal flag bit that recorded the fact that case
914        dependency changed within the pattern. This was once needed for "required
915        byte" processing, but is no longer used. This recovers a now-scarce options
916        bit. Also moved the least significant internal flag bit to the most-
917        significant bit of the word, which was not previously used (hangover from
918        the days when it was an int rather than a uint) to free up another bit for
919        the future.
921    23. Added support for CRLF line endings as well as CR and LF. As well as the
922        default being selectable at build time, it can now be changed at runtime
923        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
924        specify that it is scanning data with non-default line endings.
926    24. Changed the definition of CXXLINK to make it agree with the definition of
927        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
929    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
930        recursions. This makes a big different to stack usage for some patterns.
932    26. If a subpattern containing a named recursion or subroutine reference such
933        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
934        the space required for the compiled pattern went wrong and gave too small a
935        value. Depending on the environment, this could lead to "Failed: internal
936        error: code overflow at offset 49" or "glibc detected double free or
937        corruption" errors.
939    27. Applied patches from Google (a) to support the new newline modes and (b) to
940        advance over multibyte UTF-8 characters in GlobalReplace.
942    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
943        difference for some implementation of PCRE in some Windows version.
945    29. Added some extra testing facilities to pcretest:
947        \q<number>   in a data line sets the "match limit" value
948        \Q<number>   in a data line sets the "match recursion limt" value
949        -S <number>  sets the stack size, where <number> is in megabytes
951        The -S option isn't available for Windows.
954    Version 6.6 06-Feb-06
955    ---------------------
957     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
958        in pcreposix.h. I have copied the definition from pcre.h.
960     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
961        because pcre.h is no longer a built file.
963     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
964        not normally included in the compiled code.
967    Version 6.5 01-Feb-06
968    ---------------------
970     1. When using the partial match feature with pcre_dfa_exec(), it was not
971        anchoring the second and subsequent partial matches at the new starting
972        point. This could lead to incorrect results. For example, with the pattern
973        /1234/, partially matching against "123" and then "a4" gave a match.
975     2. Changes to pcregrep:
977        (a) All non-match returns from pcre_exec() were being treated as failures
978            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
979            error message is output. Some extra information is given for the
980            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
981            probably the only errors that are likely to be caused by users (by
982            specifying a regex that has nested indefinite repeats, for instance).
983            If there are more than 20 of these errors, pcregrep is abandoned.
985        (b) A binary zero was treated as data while matching, but terminated the
986            output line if it was written out. This has been fixed: binary zeroes
987            are now no different to any other data bytes.
989        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
990            used to set a locale for matching. The --locale=xxxx long option has
991            been added (no short equivalent) to specify a locale explicitly on the
992            pcregrep command, overriding the environment variables.
994        (d) When -B was used with -n, some line numbers in the output were one less
995            than they should have been.
997        (e) Added the -o (--only-matching) option.
999        (f) If -A or -C was used with -c (count only), some lines of context were
1000            accidentally printed for the final match.
1002        (g) Added the -H (--with-filename) option.
1004        (h) The combination of options -rh failed to suppress file names for files
1005            that were found from directory arguments.
1007        (i) Added the -D (--devices) and -d (--directories) options.
1009        (j) Added the -F (--fixed-strings) option.
1011        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1013        (l) Added the --colo(u)r option.
1015        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1016            is not present by default.
1018     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1019        items such as (?R) or (?1), when the recursion could match a number of
1020        alternatives. If it matched one of the alternatives, but subsequently,
1021        outside the recursion, there was a failure, the code tried to back up into
1022        the recursion. However, because of the way PCRE is implemented, this is not
1023        possible, and the result was an incorrect result from the match.
1025        In order to prevent this happening, the specification of recursion has
1026        been changed so that all such subpatterns are automatically treated as
1027        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1029     4. I had overlooked the fact that, in some locales, there are characters for
1030        which isalpha() is true but neither isupper() nor islower() are true. In
1031        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1032        and ordfeminine) are like this. This affected the treatment of \w and \W
1033        when they appeared in character classes, but not when they appeared outside
1034        a character class. The bit map for "word" characters is now created
1035        separately from the results of isalnum() instead of just taking it from the
1036        upper, lower, and digit maps. (Plus the underscore character, of course.)
1038     5. The above bug also affected the handling of POSIX character classes such as
1039        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1040        permanent tables. Instead, the bit maps for such a class were previously
1041        created as the appropriate unions of the upper, lower, and digit bitmaps.
1042        Now they are created by subtraction from the [[:word:]] class, which has
1043        its own bitmap.
1045     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1046        It is created by subtracting the vertical space characters (\x09, \x0a,
1047        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1048        subtraction was done in the overall bitmap for a character class, meaning
1049        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1050        be recognized. This bug has been fixed.
1052     7. Patches from the folks at Google:
1054          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1055          real life, but is still worth protecting against".
1057          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1058          regular expressions".
1060          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1061          have it.
1063          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1064          "configure" and the latter not, in order to fix a problem somebody had
1065          with compiling the Arg class on HP-UX.
1067          (e) Improve the error-handling of the C++ wrapper a little bit.
1069          (f) New tests for checking recursion limiting.
1071     8. The pcre_memmove() function, which is used only if the environment does not
1072        have a standard memmove() function (and is therefore rarely compiled),
1073        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1074        returning a result (though PCRE never actually uses the result).
1076     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1077        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1078        returned instead of calling malloc() with an overflowing number that would
1079        most likely cause subsequent chaos.
1081    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1083    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1084        with this option is matched, the nmatch and pmatch options of regexec() are
1085        ignored.
1087    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1088        provided in case anyone wants to the the POSIX interface with UTF-8
1089        strings.
1091    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1092        C++ linking (needed for some HP-UX environments).
1094    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1095        (unused parameter) and in the pcre_printint() function (omitted "default"
1096        switch label when the default is to do nothing).
1098    15. Added some code to make it possible, when PCRE is compiled as a C++
1099        library, to replace subject pointers for pcre_exec() with a smart pointer
1100        class, thus making it possible to process discontinuous strings.
1102    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1103        much the same function. They were added by different people who were trying
1104        to make PCRE easy to compile on non-Unix systems. It has been suggested
1105        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1106        for compiling on Windows systems. I have therefore replaced it with
1107        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1108        defaults to "extern" for C or "extern C" for C++, which works fine on
1109        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1110        SCOPE with something explicit in config.h. In addition:
1112        (a) pcreposix.h still had just "extern" instead of either of these macros;
1113            I have replaced it with PCRE_DATA_SCOPE.
1115        (b) Functions such as _pcre_xclass(), which are internal to the library,
1116            but external in the C sense, all had PCRE_EXPORT in their definitions.
1117            This is apparently wrong for the Windows case, so I have removed it.
1118            (It makes no difference on Unix-like systems.)
1120    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1121        of recursive calls to match(). This is different to MATCH_LIMIT because
1122        that limits the total number of calls to match(), not all of which increase
1123        the depth of recursion. Limiting the recursion depth limits the amount of
1124        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1125        when PCRE is compiled, and changed at run time. A patch from Google adds
1126        this functionality to the C++ interface.
1128    18. Changes to the handling of Unicode character properties:
1130        (a) Updated the table to Unicode 4.1.0.
1132        (b) Recognize characters that are not in the table as "Cn" (undefined).
1134        (c) I revised the way the table is implemented to a much improved format
1135            which includes recognition of ranges. It now supports the ranges that
1136            are defined in UnicodeData.txt, and it also amalgamates other
1137            characters into ranges. This has reduced the number of entries in the
1138            table from around 16,000 to around 3,000, thus reducing its size
1139            considerably. I realized I did not need to use a tree structure after
1140            all - a binary chop search is just as efficient. Having reduced the
1141            number of entries, I extended their size from 6 bytes to 8 bytes to
1142            allow for more data.
1144        (d) Added support for Unicode script names via properties such as \p{Han}.
1146    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1147        matching that character.
1149    20. When matching a repeated Unicode property with a minimum greater than zero,
1150        (for example \pL{2,}), PCRE could look past the end of the subject if it
1151        reached it while seeking the minimum number of characters. This could
1152        happen only if some of the characters were more than one byte long, because
1153        there is a check for at least the minimum number of bytes.
1155    21. Refactored the implementation of \p and \P so as to be more general, to
1156        allow for more different types of property in future. This has changed the
1157        compiled form incompatibly. Anybody with saved compiled patterns that use
1158        \p or \P will have to recompile them.
1160    22. Added "Any" and "L&" to the supported property types.
1162    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1163        but give a compile time error if the value is greater than 0xff.
1165    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1166        accidentally not being installed or uninstalled.
1168    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1169        made were to insert the current release number. This seemed silly, because
1170        it made things harder for people building PCRE on systems that don't run
1171        "configure". I have turned pcre.h into a distributed file, no longer built
1172        by "configure", with the version identification directly included. There is
1173        no longer a pcre.h.in file.
1175        However, this change necessitated a change to the pcre-config script as
1176        well. It is built from pcre-config.in, and one of the substitutions was the
1177        release number. I have updated configure.ac so that ./configure now finds
1178        the release number by grepping pcre.h.
1180    26. Added the ability to run the tests under valgrind.
1183    Version 6.4 05-Sep-05
1184    ---------------------
1186     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1187        "--" to be printed when multiple files were scanned, even when none of the
1188        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1189        consider it to be a bug, and have restored the previous behaviour.
1191     2. A couple of code tidies to get rid of compiler warnings.
1193     3. The pcretest program used to cheat by referring to symbols in the library
1194        whose names begin with _pcre_. These are internal symbols that are not
1195        really supposed to be visible externally, and in some environments it is
1196        possible to suppress them. The cheating is now confined to including
1197        certain files from the library's source, which is a bit cleaner.
1199     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1200        file's purpose clearer.
1202     5. Reorganized pcre_ucp_findchar().
1205    Version 6.3 15-Aug-05
1206    ---------------------
1208     1. The file libpcre.pc.in did not have general read permission in the tarball.
1210     2. There were some problems when building without C++ support:
1212        (a) If C++ support was not built, "make install" and "make test" still
1213            tried to test it.
1215        (b) There were problems when the value of CXX was explicitly set. Some
1216            changes have been made to try to fix these, and ...
1218        (c) --disable-cpp can now be used to explicitly disable C++ support.
1220        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1221            backslash in a target when C++ was disabled. This confuses some
1222            versions of "make", apparently. Using an intermediate variable solves
1223            this. (Same for CPP_LOBJ.)
1225     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1226        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1227        necessary on certain architectures.
1229     4. Added a setting of -export-symbols-regex to the link command to remove
1230        those symbols that are exported in the C sense, but actually are local
1231        within the library, and not documented. Their names all begin with
1232        "_pcre_". This is not a perfect job, because (a) we have to except some
1233        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1234        available (and never for static libraries). I have made a note to try to
1235        find a way round (a) in the future.
1238    Version 6.2 01-Aug-05
1239    ---------------------
1241     1. There was no test for integer overflow of quantifier values. A construction
1242        such as {1111111111111111} would give undefined results. What is worse, if
1243        a minimum quantifier for a parenthesized subpattern overflowed and became
1244        negative, the calculation of the memory size went wrong. This could have
1245        led to memory overwriting.
1247     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1249     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1250        operating environments where this matters.
1252     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1253        PCRE options from within the C++ wrapper.
1255     5. Named capturing subpatterns were not being correctly counted when a pattern
1256        was compiled. This caused two problems: (a) If there were more than 100
1257        such subpatterns, the calculation of the memory needed for the whole
1258        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1259        back references of the form \12, where the number was greater than 9, were
1260        not recognized as back references, even though there were sufficient
1261        previous subpatterns.
1263     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1264        versions of gcc, e.g. 2.95.4.
1267    Version 6.1 21-Jun-05
1268    ---------------------
1270     1. There was one reference to the variable "posix" in pcretest.c that was not
1271        surrounded by "#if !defined NOPOSIX".
1273     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1274        the cross-check on the old pcre_info() function, for the benefit of the
1275        cut-down version of PCRE that is currently imported into Exim.
1277     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1278        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1279        patterns that start (?i) but I don't think that matters. The use of (?i) is
1280        just an example; this all applies to the other options as well.
1282     4. Since libtool seems to echo the compile commands it is issuing, the output
1283        from "make" can be reduced a bit by putting "@" in front of each libtool
1284        compile command.
1286     5. Patch from the folks at Google for configure.in to be a bit more thorough
1287        in checking for a suitable C++ installation before trying to compile the
1288        C++ stuff. This should fix a reported problem when a compiler was present,
1289        but no suitable headers.
1291     6. The man pages all had just "PCRE" as their title. I have changed them to
1292        be the relevant file name. I have also arranged that these names are
1293        retained in the file doc/pcre.txt, which is a concatenation in text format
1294        of all the man pages except the little individual ones for each function.
1296     7. The NON-UNIX-USE file had not been updated for the different set of source
1297        files that come with release 6. I also added a few comments about the C++
1298        wrapper.
1301    Version 6.0 07-Jun-05
1302    ---------------------
1304     1. Some minor internal re-organization to help with my DFA experiments.
1306     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1307        didn't matter for the library itself when fully configured, but did matter
1308        when compiling without UCP support, or within Exim, where the ucp files are
1309        not imported.
1311     3. Refactoring of the library code to split up the various functions into
1312        different source modules. The addition of the new DFA matching code (see
1313        below) to a single monolithic source would have made it really too
1314        unwieldy, quite apart from causing all the code to be include in a
1315        statically linked application, when only some functions are used. This is
1316        relevant even without the DFA addition now that patterns can be compiled in
1317        one application and matched in another.
1319        The downside of splitting up is that there have to be some external
1320        functions and data tables that are used internally in different modules of
1321        the library but which are not part of the API. These have all had their
1322        names changed to start with "_pcre_" so that they are unlikely to clash
1323        with other external names.
1325     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1326        a different (DFA) algorithm. Although it is slower than the original
1327        function, it does have some advantages for certain types of matching
1328        problem.
1330     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1331        including restarting after a partial match.
1333     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1334        defined when compiling for Windows was sent to me. I have put it into the
1335        code, though I have no means of testing or verifying it.
1337     7. Added the pcre_refcount() auxiliary function.
1339     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1340        match before or at the first newline in the subject string. In pcretest,
1341        the /f option on a pattern can be used to set this.
1343     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1344        would behave wrongly. This has been present in PCRE since release 4.0.
1346    10. A number of changes to the pcregrep command:
1348        (a) Refactored how -x works; insert ^(...)$ instead of setting
1349            PCRE_ANCHORED and checking the length, in preparation for adding
1350            something similar for -w.
1352        (b) Added the -w (match as a word) option.
1354        (c) Refactored the way lines are read and buffered so as to have more
1355            than one at a time available.
1357        (d) Implemented a pcregrep test script.
1359        (e) Added the -M (multiline match) option. This allows patterns to match
1360            over several lines of the subject. The buffering ensures that at least
1361            8K, or the rest of the document (whichever is the shorter) is available
1362            for matching (and similarly the previous 8K for lookbehind assertions).
1364        (f) Changed the --help output so that it now says
1366              -w, --word-regex(p)
1368            instead of two lines, one with "regex" and the other with "regexp"
1369            because that confused at least one person since the short forms are the
1370            same. (This required a bit of code, as the output is generated
1371            automatically from a table. It wasn't just a text change.)
1373        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1374            option but starts with a hyphen. Could be a pattern or a path name
1375            starting with a hyphen, for instance.
1377        (h) "-" can be given as a file name to represent stdin.
1379        (i) When file names are being printed, "(standard input)" is used for
1380            the standard input, for compatibility with GNU grep. Previously
1381            "<stdin>" was used.
1383        (j) The option --label=xxx can be used to supply a name to be used for
1384            stdin when file names are being printed. There is no short form.
1386        (k) Re-factored the options decoding logic because we are going to add
1387            two more options that take data. Such options can now be given in four
1388            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1390        (l) Added the -A, -B, and -C options for requesting that lines of context
1391            around matches be printed.
1393        (m) Added the -L option to print the names of files that do not contain
1394            any matching lines, that is, the complement of -l.
1396        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1397            continue to scan other files.
1399        (o) The -s option was incorrectly implemented. For compatibility with other
1400            greps, it now suppresses the error message for a non-existent or non-
1401            accessible file (but not the return code). There is a new option called
1402            -q that suppresses the output of matching lines, which was what -s was
1403            previously doing.
1405        (p) Added --include and --exclude options to specify files for inclusion
1406            and exclusion when recursing.
1408    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1409        Hopefully, it now does.
1411    12. Missing cast in pcre_study().
1413    13. Added an "uninstall" target to the makefile.
1415    14. Replaced "extern" in the function prototypes in Makefile.in with
1416        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1417        world, but is set differently for Windows.
1419    15. Added a second compiling function called pcre_compile2(). The only
1420        difference is that it has an extra argument, which is a pointer to an
1421        integer error code. When there is a compile-time failure, this is set
1422        non-zero, in addition to the error test pointer being set to point to an
1423        error message. The new argument may be NULL if no error number is required
1424        (but then you may as well call pcre_compile(), which is now just a
1425        wrapper). This facility is provided because some applications need a
1426        numeric error indication, but it has also enabled me to tidy up the way
1427        compile-time errors are handled in the POSIX wrapper.
1429    16. Added VPATH=.libs to the makefile; this should help when building with one
1430        prefix path and installing with another. (Or so I'm told by someone who
1431        knows more about this stuff than I do.)
1433    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1434        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1435        match everything, including newlines. This is not POSIX-compatible, but
1436        somebody wanted the feature. From pcretest it can be activated by using
1437        both the P and the s flags.
1439    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1441    19. libpcre.pc was being incorrectly installed as executable.
1443    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1444        it now also looks for '\r' so that it will work unmodified on Windows.
1446    21. Added Google's contributed C++ wrapper to the distribution.
1448    22. Added some untidy missing memory free() calls in pcretest, to keep
1449        Electric Fence happy when testing.
1453    Version 5.0 13-Sep-04
1454    ---------------------
1456     1. Internal change: literal characters are no longer packed up into items
1457        containing multiple characters in a single byte-string. Each character
1458        is now matched using a separate opcode. However, there may be more than one
1459        byte in the character in UTF-8 mode.
1461     2. The pcre_callout_block structure has two new fields: pattern_position and
1462        next_item_length. These contain the offset in the pattern to the next match
1463        item, and its length, respectively.
1465     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1466        insertion of callouts before each pattern item. Added the /C option to
1467        pcretest to make use of this.
1469     4. On the advice of a Windows user, the lines
1471          #if defined(_WIN32) || defined(WIN32)
1472          _setmode( _fileno( stdout ), 0x8000 );
1473          #endif  /* defined(_WIN32) || defined(WIN32) */
1475        have been added to the source of pcretest. This apparently does useful
1476        magic in relation to line terminators.
1478     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1479        for the benefit of those environments where the "b" makes a difference.
1481     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1482        to know about it. I have put a hack into configure.in that adds in code
1483        to set GCC=yes if CC=icc. This seems to end up at a point in the
1484        generated configure script that is early enough to affect the setting of
1485        compiler options, which is what is needed, but I have no means of testing
1486        whether it really works. (The user who reported this had patched the
1487        generated configure script, which of course I cannot do.)
1489        LATER: After change 22 below (new libtool files), the configure script
1490        seems to know about icc (and also ecc). Therefore, I have commented out
1491        this hack in configure.in.
1493     7. Added support for pkg-config (2 patches were sent in).
1495     8. Negated POSIX character classes that used a combination of internal tables
1496        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1497        [[:^ascii]]. Typically, they would match almost any characters. The other
1498        POSIX classes were not broken in this way.
1500     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1501        to find the match, as PCRE was deluded into thinking that the match had to
1502        start at the start point or following a newline. The same bug applied to
1503        patterns with negative forward assertions or any backward assertions
1504        preceding ".*" at the start, unless the pattern required a fixed first
1505        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1507    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1508        starting at the last subject character, bytes beyond the end of the subject
1509        string were read.
1511    11. Renamed the variable "class" as "classbits" to make life easier for C++
1512        users. (Previously there was a macro definition, but it apparently wasn't
1513        enough.)
1515    12. Added the new field "tables" to the extra data so that tables can be passed
1516        in at exec time, or the internal tables can be re-selected. This allows
1517        a compiled regex to be saved and re-used at a later time by a different
1518        program that might have everything at different addresses.
1520    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1521        -R library as well as a -L library.
1523    14. The debugging options of pcretest (-d on the command line or D on a
1524        pattern) showed incorrect output for anything following an extended class
1525        that contained multibyte characters and which was followed by a quantifier.
1527    15. Added optional support for general category Unicode character properties
1528        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1529        support. It adds about 90K to the size of the library. The meanings of the
1530        inbuilt class escapes such as \d and \s have NOT been changed.
1532    16. Updated pcredemo.c to include calls to free() to release the memory for the
1533        compiled pattern.
1535    17. The generated file chartables.c was being created in the source directory
1536        instead of in the building directory. This caused the build to fail if the
1537        source directory was different from the building directory, and was
1538        read-only.
1540    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1541        file. No doubt somebody will tell me if they don't make sense... Also added
1542        Dan Mooney's comments about building on OpenVMS.
1544    19. Added support for partial matching via the PCRE_PARTIAL option for
1545        pcre_exec() and the \P data escape in pcretest.
1547    20. Extended pcretest with 3 new pattern features:
1549        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1550              write the compiled pattern to the file whose name is "rest-of-line".
1551              This is a straight binary dump of the data, with the saved pointer to
1552              the character tables forced to be NULL. The study data, if any, is
1553              written too. After writing, pcretest reads a new pattern.
1555        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1556              compiled pattern from the given file. There must not be any
1557              occurrences of "<" in the file name (pretty unlikely); if there are,
1558              pcretest will instead treat the initial "<" as a pattern delimiter.
1559              After reading in the pattern, pcretest goes on to read data lines as
1560              usual.
1562        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1563              and 16-bit fields in a compiled pattern, to simulate a pattern that
1564              was compiled on a host of opposite endianness.
1566    21. The pcre-exec() function can now cope with patterns that were compiled on
1567        hosts of opposite endianness, with this restriction:
1569          As for any compiled expression that is saved and used later, the tables
1570          pointer field cannot be preserved; the extra_data field in the arguments
1571          to pcre_exec() should be used to pass in a tables address if a value
1572          other than the default internal tables were used at compile time.
1574    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1575        now diagnosed as an error. Previously, most of the time, a negative number
1576        would have been treated as zero, but if in addition "ovector" was passed as
1577        NULL, a crash could occur.
1579    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1580        new versions from the libtool 1.5 distribution (the last one is a copy of
1581        a file called libtool.m4). This seems to have fixed the need to patch
1582        "configure" to support Darwin 1.3 (which I used to do). However, I still
1583        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1584        workstation).
1586    24. Changed the PCRE licence to be the more standard "BSD" licence.
1589    Version 4.5 01-Dec-03
1590    ---------------------
1592     1. There has been some re-arrangement of the code for the match() function so
1593        that it can be compiled in a version that does not call itself recursively.
1594        Instead, it keeps those local variables that need separate instances for
1595        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1596        needs to "recurse". Keeping track of where control must go is done by means
1597        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1598        hide most of the details from the main code, and operates only if
1599        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1600        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1601        operating.
1603        To make it easier for callers to provide specially tailored get/free
1604        functions for this usage, two new functions, pcre_stack_malloc, and
1605        pcre_stack_free, are used. They are always called in strict stacking order,
1606        and the size of block requested is always the same.
1608        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1609        PCRE has been compiled to use the stack or the heap for recursion. The
1610        -C option of pcretest uses this to show which version is compiled.
1612        A new data escape \S, is added to pcretest; it causes the amounts of store
1613        obtained and freed by both kinds of malloc/free at match time to be added
1614        to the output.
1616     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1617        what's available on my current Linux desktop machine.
1619     3. When matching a UTF-8 string, the test for a valid string at the start has
1620        been extended. If start_offset is not zero, PCRE now checks that it points
1621        to a byte that is the start of a UTF-8 character. If not, it returns
1622        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1623        this is necessary because there may be backward assertions in the pattern.
1624        When matching the same subject several times, it may save resources to use
1625        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1627     4. The code for checking the validity of UTF-8 strings has been tightened so
1628        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1629        containing "overlong sequences".
1631     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1632        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1633        should have been "&", but it just so happened that all the cases this let
1634        through by mistake were picked up later in the function.
1636     6. I had used a variable called "isblank" - this is a C99 function, causing
1637        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1639     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1640        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1641        so the version is shown; (c) stop "make test" echoing "./RunTest".
1643     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1645     9. The prototype for memmove() for systems that don't have it was using
1646        size_t, but the inclusion of the header that defines size_t was later. I've
1647        moved the #includes for the C headers earlier to avoid this.
1649    10. Added some adjustments to the code to make it easier to compiler on certain
1650        special systems:
1652          (a) Some "const" qualifiers were missing.
1653          (b) Added the macro EXPORT before all exported functions; by default this
1654              is defined to be empty.
1655          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1656              that it reads its output file name as an argument instead of writing
1657              to the standard output and assuming this can be redirected.
1659    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1660        class containing characters with values greater than 255, PCRE compilation
1661        went into a loop.
1663    12. A recursive reference to a subpattern that was within another subpattern
1664        that had a minimum quantifier of zero caused PCRE to crash. For example,
1665        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1666        recursion. If the recursively-called subpattern itself had a zero repeat,
1667        that was OK.
1669    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1670        buffer into which it was copied (for escape processing) was still set at
1671        1024, so long lines caused crashes.
1673    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1674        "internal error: code overflow...". This applied to any character class
1675        that was followed by a possessive quantifier.
1677    15. Modified the Makefile to add libpcre.la as a prerequisite for
1678        libpcreposix.la because I was told this is needed for a parallel build to
1679        work.
1681    16. If a pattern that contained .* following optional items at the start was
1682        studied, the wrong optimizing data was generated, leading to matching
1683        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1684        matching string must start with a or b or c. The correct conclusion for
1685        this pattern is that a match can start with any character.
1688    Version 4.4 13-Aug-03
1689    ---------------------
1691     1. In UTF-8 mode, a character class containing characters with values between
1692        127 and 255 was not handled correctly if the compiled pattern was studied.
1693        In fixing this, I have also improved the studying algorithm for such
1694        classes (slightly).
1696     2. Three internal functions had redundant arguments passed to them. Removal
1697        might give a very teeny performance improvement.
1699     3. Documentation bug: the value of the capture_top field in a callout is *one
1700        more than* the number of the hightest numbered captured substring.
1702     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1703        in incorrectly linking with a previously installed version. They now link
1704        explicitly with libpcre.la.
1706     5. configure.in no longer needs to recognize Cygwin specially.
1708     6. A problem in pcre.in for Windows platforms is fixed.
1710     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1711        pcretest, it used to include the size of the study block as part of its
1712        output. Unfortunately, the structure contains a field that has a different
1713        size on different hardware architectures. This meant that the tests that
1714        showed this size failed. As the block is currently always of a fixed size,
1715        this information isn't actually particularly useful in pcretest output, so
1716        I have just removed it.
1718     8. Three pre-processor statements accidentally did not start in column 1.
1719        Sadly, there are *still* compilers around that complain, even though
1720        standard C has not required this for well over a decade. Sigh.
1722     9. In pcretest, the code for checking callouts passed small integers in the
1723        callout_data field, which is a void * field. However, some picky compilers
1724        complained about the casts involved for this on 64-bit systems. Now
1725        pcretest passes the address of the small integer instead, which should get
1726        rid of the warnings.
1728    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1729        both compile and run time, and gives an error if an invalid UTF-8 sequence
1730        is found. There is a option for disabling this check in cases where the
1731        string is known to be correct and/or the maximum performance is wanted.
1733    11. In response to a bug report, I changed one line in Makefile.in from
1735            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1736        to
1737            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1739        to look similar to other lines, but I have no way of telling whether this
1740        is the right thing to do, as I do not use Windows. No doubt I'll get told
1741        if it's wrong...
1744    Version 4.3 21-May-03
1745    ---------------------
1747    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1748       Makefile.
1750    2. Some refactoring to improve the quality of the code:
1752       (i)   The utf8_table... variables are now declared "const".
1754       (ii)  The code for \cx, which used the "case flipping" table to upper case
1755             lower case letters, now just substracts 32. This is ASCII-specific,
1756             but the whole concept of \cx is ASCII-specific, so it seems
1757             reasonable.
1759       (iii) PCRE was using its character types table to recognize decimal and
1760             hexadecimal digits in the pattern. This is silly, because it handles
1761             only 0-9, a-f, and A-F, but the character types table is locale-
1762             specific, which means strange things might happen. A private
1763             table is now used for this - though it costs 256 bytes, a table is
1764             much faster than multiple explicit tests. Of course, the standard
1765             character types table is still used for matching digits in subject
1766             strings against \d.
1768       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1769             ending in _t are). So I've renamed it as ESC_tee.
1771    3. The first argument for regexec() in the POSIX wrapper should have been
1772       defined as "const".
1774    4. Changed pcretest to use malloc() for its buffers so that they can be
1775       Electric Fenced for debugging.
1777    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1778       to read one or more bytes before the start of the subject string. Often this
1779       had no effect on PCRE's behaviour, but in some circumstances it could
1780       provoke a segmentation fault.
1782    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1783       to try to read one or more bytes before the start of the subject string.
1785    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1786       UTF-8 support could misbehave in various ways if the subject string
1787       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1788       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1789       back over UTF-8 characters.)
1792    Version 4.2 14-Apr-03
1793    ---------------------
1795    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1797    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1798         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1799         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1800         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1801         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1802           and BUILD_EXEEXT
1803         Note: automatic setting of the BUILD variables is not yet working
1804         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1805           compile-time but not at link-time
1806         [LINK]: use for linking executables only
1807         make different versions for Windows and non-Windows
1808         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1809           libraries
1810         [LINK_FOR_BUILD]: new variable
1811         [OBJEXT]: use throughout
1812         [EXEEXT]: use throughout
1813         <winshared>: new target
1814         <wininstall>: new target
1815         <dftables.o>: use native compiler
1816         <dftables>: use native linker
1817         <install>: handle Windows platform correctly
1818         <clean>: ditto
1819         <check>: ditto
1820         copy DLL to top builddir before testing
1822       As part of these changes, -no-undefined was removed again. This was reported
1823       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1824       in any case.
1826    3. Some tidies to get rid of compiler warnings:
1828       . In the match_data structure, match_limit was an unsigned long int, whereas
1829         match_call_count was an int. I've made them both unsigned long ints.
1831       . In pcretest the fact that a const uschar * doesn't automatically cast to
1832         a void * provoked a warning.
1834       . Turning on some more compiler warnings threw up some "shadow" variables
1835         and a few more missing casts.
1837    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1838       option, a class that contained a single character with a value between 128
1839       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1841    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1842       option, a class that contained several characters, but with at least one
1843       whose value was between 128 and 255 caused PCRE to crash.
1846    Version 4.1 12-Mar-03
1847    ---------------------
1849    1. Compiling with gcc -pedantic found a couple of places where casts were
1850    needed, and a string in dftables.c that was longer than standard compilers are
1851    required to support.
1853    2. Compiling with Sun's compiler found a few more places where the code could
1854    be tidied up in order to avoid warnings.
1856    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1857    first of these names is deprecated in the latest Autoconf in favour of the name
1858    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1859    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1860    analogy I have changed it to CFLAGS_FOR_BUILD.
1862    4. Added -no-undefined to the linking command in the Makefile, because this is
1863    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1864    linking step for the pcreposix library.
1866    5. PCRE was failing to diagnose the case of two named groups with the same
1867    name.
1869    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1870    literal character that is needed in the subject for a match, and scans along to
1871    ensure that it is present before embarking on the full matching process. This
1872    saves time in cases of nested unlimited repeats that are never going to match.
1873    Problem: the scan can take a lot of time if the subject is very long (e.g.
1874    megabytes), thus penalizing straightforward matches. It is now done only if the
1875    amount of subject to be scanned is less than 1000 bytes.
1877    7. A lesser problem with the same optimization is that it was recording the
1878    first character of an anchored pattern as "needed", thus provoking a search
1879    right along the subject, even when the first match of the pattern was going to
1880    fail. The "needed" character is now not set for anchored patterns, unless it
1881    follows something in the pattern that is of non-fixed length. Thus, it still
1882    fulfils its original purpose of finding quick non-matches in cases of nested
1883    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1886    Version 4.0 17-Feb-03
1887    ---------------------
1889    1. If a comment in an extended regex that started immediately after a meta-item
1890    extended to the end of string, PCRE compiled incorrect data. This could lead to
1891    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1893    2. Moved to autoconf 2.53 and libtool 1.4.2.
1895    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1896    the special perltest8 script is no longer needed - all the tests can be run
1897    from a single perltest script.
1899    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1900    by \s. It has now been removed in PCRE. This means it isn't recognized as
1901    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1902    class [:space:] *does* include VT, thereby creating a mess.
1904    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1905    space and tab.
1907    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1908    its new features into the main test script, reducing the number of scripts.
1910    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1911    were backward compatible, and made the (?i) apply to the whole pattern, as if
1912    /i were given. Now it behaves more logically, and applies the option setting
1913    only to what follows. PCRE has been changed to follow suit. However, if it
1914    finds options settings right at the start of the pattern, it extracts them into
1915    the global options, as before. Thus, they show up in the info data.
1917    8. Added support for the \Q...\E escape sequence. Characters in between are
1918    treated as literals. This is slightly different from Perl in that $ and @ are
1919    also handled as literals inside the quotes. In Perl, they will cause variable
1920    interpolation. Note the following examples:
1922        Pattern            PCRE matches      Perl matches
1924        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1925        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1926        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1928    For compatibility with Perl, \Q...\E sequences are recognized inside character
1929    classes as well as outside them.
1931    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1932    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1933    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1934    signed/unsigned warnings.
1936    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1937    option for pcretest, so I've replaced it by a simple function that does just
1938    that job.
1940    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1941    "pcregrep -".
1943    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1944    Java package. This provides some syntactic sugar for simple cases of what my
1945    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1946    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1947    item, you can use this simplified notation. Note that only makes sense with
1948    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1949    greediness, whatever the setting of the PCRE_UNGREEDY option.
1951    13. A change of greediness default within a pattern was not taking effect at
1952    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1953    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1954    was abstracted outside.
1956    14. PCRE now supports the \G assertion. It is true when the current matching
1957    position is at the start point of the match. This differs from \A when the
1958    starting offset is non-zero. Used with the /g option of pcretest (or similar
1959    code), it works in the same way as it does for Perl's /g option. If all
1960    alternatives of a regex begin with \G, the expression is anchored to the start
1961    match position, and the "anchored" flag is set in the compiled expression.
1963    15. Some bugs concerning the handling of certain option changes within patterns
1964    have been fixed. These applied to options other than (?ims). For example,
1965    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1966    been the other way round. Some of this was related to change 7 above.
1968    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1969    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1970    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1971    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1973    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1974    mode. Unlike ".", it always matches newline, whatever the setting of
1975    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1976    assertions. Perl allows it, but it doesn't (in general) work because it can't
1977    calculate the length of the lookbehind. At least, that's the case for Perl
1978    5.8.0 - I've been told they are going to document that it doesn't work in
1979    future.
1981    18. Added an error diagnosis for escapes that PCRE does not support: these are
1982    \L, \l, \N, \P, \p, \U, \u, and \X.
1984    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1985    reading past the end of the pattern in cases such as /[abcd/.
1987    20. PCRE was getting more memory than necessary for patterns with classes that
1988    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1990    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1991    compiling PCRE for use with Virtual Pascal.
1993    22. Small fix to the Makefile to make it work properly if the build is done
1994    outside the source tree.
1996    23. Added a new extension: a condition to go with recursion. If a conditional
1997    subpattern starts with (?(R) the "true" branch is used if recursion has
1998    happened, whereas the "false" branch is used only at the top level.
2000    24. When there was a very long string of literal characters (over 255 bytes
2001    without UTF support, over 250 bytes with UTF support), the computation of how
2002    much memory was required could be incorrect, leading to segfaults or other
2003    strange effects.
2005    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2006    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2007    there was a subsequent back reference to those brackets. This meant that, for
2008    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2009    possible to check for precisely this case. All we can do is abandon the
2010    optimization if .* occurs inside capturing brackets when there are any back
2011    references whatsoever. (See below for a better fix that came later.)
2013    26. The handling of the optimization for finding the first character of a
2014    non-anchored pattern, and for finding a character that is required later in the
2015    match were failing in some cases. This didn't break the matching; it just
2016    failed to optimize when it could. The way this is done has been re-implemented.
2018    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2020    28. Added a new feature that provides some of the functionality that Perl
2021    provides with (?{...}). The facility is termed a "callout". The way it is done
2022    in PCRE is for the caller to provide an optional function, by setting
2023    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2024    global variable. By default it is unset, which disables all calling out. To get
2025    the function called, the regex must include (?C) at appropriate points. This
2026    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2027    This provides a means of identifying different callout points. When PCRE
2028    reaches such a point in the regex, if pcre_callout has been set, the external
2029    function is called. It is provided with data in a structure called
2030    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2031    matching continues; if it returns a non-zero value, the match at the current
2032    point fails. However, backtracking will occur if possible. [This was changed
2033    later and other features added - see item 49 below.]
2035    29. pcretest is upgraded to test the callout functionality. It provides a
2036    callout function that displays information. By default, it shows the start of
2037    the match and the current position in the text. There are some new data escapes
2038    to vary what happens:
2040        \C+         in addition, show current contents of captured substrings
2041        \C-         do not supply a callout function
2042        \C!n        return 1 when callout number n is reached
2043        \C!n!m      return 1 when callout number n is reached for the mth time
2045    30. If pcregrep was called with the -l option and just a single file name, it
2046    output "<stdin>" if a match was found, instead of the file name.
2048    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2049    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2050    pcre_exec(). This saves a malloc/free per call. The default value of
2051    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2052    when configuring.
2054    32. The default maximum size of a compiled pattern is 64K. There have been a
2055    few cases of people hitting this limit. The code now uses macros to handle the
2056    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2057    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2058    configuring. Tests 2 and 5 work only with 2-byte links because they output
2059    debugging information about compiled patterns.
2061    33. Internal code re-arrangements:
2063    (a) Moved the debugging function for printing out a compiled regex into
2064        its own source file (printint.c) and used #include to pull it into
2065        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2066        separate copies.
2068    (b) Defined the list of op-code names for debugging as a macro in
2069        internal.h so that it is next to the definition of the opcodes.
2071    (c) Defined a table of op-code lengths for simpler skipping along compiled
2072        code. This is again a macro in internal.h so that it is next to the
2073        definition of the opcodes.
2075    34. Added support for recursive calls to individual subpatterns, along the
2076    lines of Robin Houston's patch (but implemented somewhat differently).
2078    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2079    allow it to read and process whole directories in Win32. This code was
2080    contributed by Lionel Fourquaux; it has not been tested by me.
2082    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2083    used to name a group. Names consist of alphanumerics and underscores, and must
2084    be unique. Back references use the syntax (?P=name) and recursive calls use
2085    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2086    numbers. The function pcre_fullinfo() can be used after compilation to extract
2087    a name/number map. There are three relevant calls:
2089      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2090      PCRE_INFO_NAMECOUNT            yields the number of entries
2091      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2093    The map is a vector of fixed-size entries. The size of each entry depends on
2094    the length of the longest name used. The first two bytes of each entry are the
2095    group number, most significant byte first. There follows the corresponding
2096    name, zero terminated. The names are in alphabetical order.
2098    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2099    case instead of 255. Making it the same both with and without UTF-8 support
2100    means that the same test output works with both.
2102    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2103    calling malloc() with a zero argument.
2105    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2106    optimization. I've improved things by keeping a bitmap of backreferences with
2107    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2108    fact referenced, the optimization can be applied. It is unlikely that a
2109    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2110    the match to follow \n) will appear inside brackets with a number greater than
2111    31, but if it does, any back reference > 31 suppresses the optimization.
2113    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2114    of disabling numbered capturing parentheses. Any opening parenthesis that is
2115    not followed by ? behaves as if it were followed by ?: but named parentheses
2116    can still be used for capturing (and they will acquire numbers in the usual
2117    way).
2119    41. Redesigned the return codes from the match() function into yes/no/error so
2120    that errors can be passed back from deep inside the nested calls. A malloc
2121    failure while inside a recursive subpattern call now causes the
2122    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2124    42. It is now possible to set a limit on the number of times the match()
2125    function is called in a call to pcre_exec(). This facility makes it possible to
2126    limit the amount of recursion and backtracking, though not in a directly
2127    obvious way, because the match() function is used in a number of different
2128    circumstances. The count starts from zero for each position in the subject
2129    string (for non-anchored patterns). The default limit is, for compatibility, a
2130    large number, namely 10 000 000. You can change this in two ways:
2132    (a) When configuring PCRE before making, you can use --with-match-limit=n
2133        to set a default value for the compiled library.
2135    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2136        a different value is set. See 45 below.
2138    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2140    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2141    of things that can be changed at compile time. The first argument specifies
2142    what is wanted and the second points to where the information is to be placed.
2143    The current list of available information is:
2145      PCRE_CONFIG_UTF8
2147    The output is an integer that is set to one if UTF-8 support is available;
2148    otherwise it is set to zero.
2152    The output is an integer that it set to the value of the code that is used for
2153    newline. It is either LF (10) or CR (13).
2157    The output is an integer that contains the number of bytes used for internal
2158    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2162    The output is an integer that contains the threshold above which the POSIX
2163    interface uses malloc() for output vectors. See item 31 above.
2167    The output is an unsigned integer that contains the default limit of the number
2168    of match() calls in a pcre_exec() execution. See 42 above.
2170    44. pcretest has been upgraded by the addition of the -C option. This causes it
2171    to extract all the available output from the new pcre_config() function, and to
2172    output it. The program then exits immediately.
2174    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2175    order to support additional features. One way would have been to define
2176    pcre_exec2() (for example) with extra arguments, but this would not have been
2177    extensible, and would also have required all calls to the original function to
2178    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2179    is used for passing in "extra" data from pcre_study().
2181    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2182    contains the following fields:
2184      flags         a bitmap indicating which of the following fields are set
2185      study_data    opaque data from pcre_study()
2186      match_limit   a way of specifying a limit on match() calls for a specific
2187                      call to pcre_exec()
2188      callout_data  data for callouts (see 49 below)
2190    The flag bits are also defined in pcre.h, and are
2196    The pcre_study() function now returns one of these new pcre_extra blocks, with
2197    the actual study data pointed to by the study_data field, and the
2198    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2199    before. That is, this change is entirely upwards-compatible and requires no
2200    change to existing code.
2202    If you want to pass in additional data to pcre_exec(), you can either place it
2203    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2204    block.
2206    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2207    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2208    times with different match limits, until it finds the minimum value needed for
2209    pcre_exec() to complete. The value is then output. This can be instructive; for
2210    most simple matches the number is quite small, but for pathological cases it
2211    gets very large very quickly.
2213    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2214    returns the size of the data block pointed to by the study_data field in a
2215    pcre_extra block, that is, the value that was passed as the argument to
2216    pcre_malloc() when PCRE was getting memory in which to place the information
2217    created by pcre_study(). The fourth argument should point to a size_t variable.
2218    pcretest has been extended so that this information is shown after a successful
2219    pcre_study() call when information about the compiled regex is being displayed.
2221    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2222    because what follows is always an absolute path. (Later: it turns out that this
2223    is more than cosmetic for MinGW, because it doesn't like empty path
2224    components.)
2226    49. Some changes have been made to the callout feature (see 28 above):
2228    (i)  A callout function now has three choices for what it returns:
2230           0  =>  success, carry on matching
2231         > 0  =>  failure at this point, but backtrack if possible
2232         < 0  =>  serious error, return this value from pcre_exec()
2234         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2235         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2236         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2237         use by callout functions. It will never be used by PCRE itself.
2239    (ii) The pcre_extra structure (see 45 above) has a void * field called
2240         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2241         pcre_callout_block structure has a field of the same name. The contents of
2242         the field passed in the pcre_extra structure are passed to the callout
2243         function in the corresponding field in the callout block. This makes it
2244         easier to use the same callout-containing regex from multiple threads. For
2245         testing, the pcretest program has a new data escape
2247           \C*n        pass the number n (may be negative) as callout_data
2249         If the callout function in pcretest receives a non-zero value as
2250         callout_data, it returns that value.
2252    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2253    there were some redundant $(CFLAGS) in commands that are now specified as
2254    $(LINK), which already includes $(CFLAGS).
2256    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2257    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2258    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2259    one-byte characters throughout. Note that case-insensitive matching applies
2260    only to characters whose values are less than 256. PCRE doesn't support the
2261    notion of cases for higher-valued characters.
2263    (i)   A character class whose characters are all within 0-255 is handled as
2264          a bit map, and the map is inverted for negative classes. Previously, a
2265          character > 255 always failed to match such a class; however it should
2266          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2268    (ii)  A negated character class with a single character < 255 is coded as
2269          "not this character" (OP_NOT). This wasn't working properly when the test
2270          character was multibyte, either singly or repeated.
2272    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2273          mode, for example: \x{100}{2,3}.
2275    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2276          singly or repeated) now correctly test multibyte characters. However,
2277          PCRE doesn't recognize any characters with values greater than 255 as
2278          digits, spaces, or word characters. Such characters always match \D, \S,
2279          and \W, and never match \d, \s, or \w.
2281    (v)   Classes may now contain characters and character ranges with values
2282          greater than 255. For example: [ab\x{100}-\x{400}].
2284    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2285          PCRE in UTF-8 mode.
2287    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2288    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2289    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2290    value.)
2292    53. The single man page has become too large. I have therefore split it up into
2293    a number of separate man pages. These also give rise to individual HTML pages;
2294    these are now put in a separate directory, and there is an index.html page that
2295    lists them all. Some hyperlinking between the pages has been installed.
2297    54. Added convenience functions for handling named capturing parentheses.
2299    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2300    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2301    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2302    are faulted.
2304    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2305    calling configure. These values are used when compiling the dftables.c program
2306    which is run to generate the source of the default character tables. They
2307    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2308    you will need to set these values.
2310    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2313    Version 3.9 02-Jan-02
2314    ---------------------
2316    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2318    2. If --disable-static was given, the building process failed when trying to
2319    build pcretest and pcregrep. (For some reason it was using libtool to compile
2320    them, which is not right, as they aren't part of the library.)
2323    Version 3.8 18-Dec-01
2324    ---------------------
2326    1. The experimental UTF-8 code was completely screwed up. It was packing the
2327    bytes in the wrong order. How dumb can you get?
2330    Version 3.7 29-Oct-01
2331    ---------------------
2333    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2334    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2335    this didn't happen under Solaris 8, where I normally test things.
2337    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2338    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2339    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2340    this fix an hour or so after the initial 3.7 release.)
2343    Version 3.6 23-Oct-01
2344    ---------------------
2346    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2347    offsets passed as NULL with zero offset count.
2349    2. The config.guess and config.sub files had not been updated when I moved to
2350    the latest autoconf.
2353    Version 3.5 15-Aug-01
2354    ---------------------
2356    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2357    had been forgotten.
2359    2. By using declared but undefined structures, we can avoid using "void"
2360    definitions in pcre.h while keeping the internal definitions of the structures
2361    private.
2363    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2364    user point of view, this means that both static and shared libraries are built
2365    by default, but this can be individually controlled. More of the work of
2366    handling this static/shared cases is now inside libtool instead of PCRE's make
2367    file.
2369    4. The pcretest utility is now installed along with pcregrep because it is
2370    useful for users (to test regexs) and by doing this, it automatically gets
2371    relinked by libtool. The documentation has been turned into a man page, so
2372    there are now .1, .txt, and .html versions in /doc.
2374    5. Upgrades to pcregrep:
2375       (i)   Added long-form option names like gnu grep.
2376       (ii)  Added --help to list all options with an explanatory phrase.
2377       (iii) Added -r, --recursive to recurse into sub-directories.
2378       (iv)  Added -f, --file to read patterns from a file.
2380    6. pcre_exec() was referring to its "code" argument before testing that
2381    argument for NULL (and giving an error if it was NULL).
2383    7. Upgraded Makefile.in to allow for compiling in a different directory from
2384    the source directory.
2386    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2387    options bits, the pointer it was passed was to an int instead of to an unsigned
2388    long int. This mattered only on 64-bit systems.
2390    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2391    generated) instead of pcre.in, which it its source. Also made the same change
2392    in several of the .c files.
2394    10. A new release of gcc defines printf() as a macro, which broke pcretest
2395    because it had an ifdef in the middle of a string argument for printf(). Fixed
2396    by using separate calls to printf().
2398    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2399    script, to force use of CR or LF instead of \n in the source. On non-Unix
2400    systems, the value can be set in config.h.
2402    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2403    absolute limit. Changed the text of the error message to make this clear, and
2404    likewise updated the man page.
2406    13. The limit of 99 on the number of capturing subpatterns has been removed.
2407    The new limit is 65535, which I hope will not be a "real" limit.
2410  Version 3.4 22-Aug-00  Version 3.4 22-Aug-00
2411  ---------------------  ---------------------

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