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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 8.37 xx-xxx-2015
5    ------------------------
7    1.  When an (*ACCEPT) is triggered inside capturing parentheses, it arranges
8        for those parentheses to be closed with whatever has been captured so far.
9        However, it was failing to mark any other groups between the hightest
10        capture so far and the currrent group as "unset". Thus, the ovector for
11        those groups contained whatever was previously there. An example is the
12        pattern /(x)|((*ACCEPT))/ when matched against "abcd".
14    2.  If an assertion condition was quantified with a minimum of zero (an odd
15        thing to do, but it happened), SIGSEGV or other misbehaviour could occur.
17    3.  If a pattern in pcretest input had the P (POSIX) modifier followed by an
18        unrecognized modifier, a crash could occur.
20    4.  An attempt to do global matching in pcretest with a zero-length ovector
21        caused a crash.
23    5.  Fixed a memory leak during matching that could occur for a subpattern
24        subroutine call (recursive or otherwise) if the number of captured groups
25        that had to be saved was greater than ten.
27    6.  Catch a bad opcode during auto-possessification after compiling a bad UTF
28        string with NO_UTF_CHECK. This is a tidyup, not a bug fix, as passing bad
29        UTF with NO_UTF_CHECK is documented as having an undefined outcome.
31    7.  A UTF pattern containing a "not" match of a non-ASCII character and a
32        subroutine reference could loop at compile time. Example: /[^\xff]((?1))/.
34    8. When a pattern is compiled, it remembers the highest back reference so that
35       when matching, if the ovector is too small, extra memory can be obtained to
36       use instead. A conditional subpattern whose condition is a check on a
37       capture having happened, such as, for example in the pattern
38       /^(?:(a)|b)(?(1)A|B)/, is another kind of back reference, but it was not
39       setting the highest backreference number. This mattered only if pcre_exec()
40       was called with an ovector that was too small to hold the capture, and there
41       was no other kind of back reference (a situation which is probably quite
42       rare). The effect of the bug was that the condition was always treated as
43       FALSE when the capture could not be consulted, leading to a incorrect
44       behaviour by pcre2_match(). This bug has been fixed.
46    9. A reference to a duplicated named group (either a back reference or a test
47       for being set in a conditional) that occurred in a part of the pattern where
48       PCRE_DUPNAMES was not set caused the amount of memory needed for the pattern
49       to be incorrectly calculated, leading to overwriting.
51    10. A mutually recursive set of back references such as (\2)(\1) caused a
52        segfault at study time (while trying to find the minimum matching length).
53        The infinite loop is now broken (with the minimum length unset, that is,
54        zero).
56    11. If an assertion that was used as a condition was quantified with a minimum
57        of zero, matching went wrong. In particular, if the whole group had
58        unlimited repetition and could match an empty string, a segfault was
59        likely. The pattern (?(?=0)?)+ is an example that caused this. Perl allows
60        assertions to be quantified, but not if they are being used as conditions,
61        so the above pattern is faulted by Perl. PCRE has now been changed so that
62        it also rejects such patterns.
64    12. A possessive capturing group such as (a)*+ with a minimum repeat of zero
65        failed to allow the zero-repeat case if pcre2_exec() was called with an
66        ovector too small to capture the group.
68    13. Fixed two bugs in pcretest that were discovered by fuzzing and reported by
69        Red Hat Product Security:
71        (a) A crash if /K and /F were both set with the option to save the compiled
72        pattern.
74        (b) Another crash if the option to print captured substrings in a callout
75        was combined with setting a null ovector, for example \O\C+ as a subject
76        string.
78    14. A pattern such as "((?2){0,1999}())?", which has a group containing a
79        forward reference repeated a large (but limited) number of times within a
80        repeated outer group that has a zero minimum quantifier, caused incorrect
81        code to be compiled, leading to the error "internal error:
82        previously-checked referenced subpattern not found" when an incorrect
83        memory address was read. This bug was reported as "heap overflow",
84        discovered by Kai Lu of Fortinet's FortiGuard Labs and given the CVE number
85        CVE-2015-2325.
87    23. A pattern such as "((?+1)(\1))/" containing a forward reference subroutine
88        call within a group that also contained a recursive back reference caused
89        incorrect code to be compiled. This bug was reported as "heap overflow",
90        discovered by Kai Lu of Fortinet's FortiGuard Labs, and given the CVE
91        number CVE-2015-2326.
93    24. Computing the size of the JIT read-only data in advance has been a source
94        of various issues, and new ones are still appear unfortunately. To fix
95        existing and future issues, size computation is eliminated from the code,
96        and replaced by on-demand memory allocation.
98    25. A pattern such as /(?i)[A-`]/, where characters in the other case are
99        adjacent to the end of the range, and the range contained characters with
100        more than one other case, caused incorrect behaviour when compiled in UTF
101        mode. In that example, the range a-j was left out of the class.
103    26. Fix JIT compilation of conditional blocks, which assertion
104        is converted to (*FAIL). E.g: /(?(?!))/.
106    27. The pattern /(?(?!)^)/ caused references to random memory. This bug was
107        discovered by the LLVM fuzzer.
109    28. The assertion (?!) is optimized to (*FAIL). This was not handled correctly
110        when this assertion was used as a condition, for example (?(?!)a|b). In
111        pcre2_match() it worked by luck; in pcre2_dfa_match() it gave an incorrect
112        error about an unsupported item.
114    29. For some types of pattern, for example /Z*(|d*){216}/, the auto-
115        possessification code could take exponential time to complete. A recursion
116        depth limit of 1000 has been imposed to limit the resources used by this
117        optimization.
119    30. A pattern such as /(*UTF)[\S\V\H]/, which contains a negated special class
120        such as \S in non-UCP mode, explicit wide characters (> 255) can be ignored
121        because \S ensures they are all in the class. The code for doing this was
122        interacting badly with the code for computing the amount of space needed to
123        compile the pattern, leading to a buffer overflow. This bug was discovered
124        by the LLVM fuzzer.
126    31. A pattern such as /((?2)+)((?1))/ which has mutual recursion nested inside
127        other kinds of group caused stack overflow at compile time. This bug was
128        discovered by the LLVM fuzzer.
130    32. A pattern such as /(?1)(?#?'){8}(a)/ which had a parenthesized comment
131        between a subroutine call and its quantifier was incorrectly compiled,
132        leading to buffer overflow or other errors. This bug was discovered by the
133        LLVM fuzzer.
135    33. The illegal pattern /(?(?<E>.*!.*)?)/ was not being diagnosed as missing an
136        assertion after (?(. The code was failing to check the character after
137        (?(?< for the ! or = that would indicate a lookbehind assertion. This bug
138        was discovered by the LLVM fuzzer.
140    34. A pattern such as /X((?2)()*+){2}+/ which has a possessive quantifier with
141        a fixed maximum following a group that contains a subroutine reference was
142        incorrectly compiled and could trigger buffer overflow. This bug was
143        discovered by the LLVM fuzzer.
145    35. A mutual recursion within a lookbehind assertion such as (?<=((?2))((?1)))
146        caused a stack overflow instead of the diagnosis of a non-fixed length
147        lookbehind assertion. This bug was discovered by the LLVM fuzzer.
149    36. The use of \K in a positive lookbehind assertion in a non-anchored pattern
150        (e.g. /(?<=\Ka)/) could make pcregrep loop.
152    37. There was a similar problem to 36 in pcretest for global matches.
154    38. If a greedy quantified \X was preceded by \C in UTF mode (e.g. \C\X*),
155        and a subsequent item in the pattern caused a non-match, backtracking over
156        the repeated \X did not stop, but carried on past the start of the subject,
157        causing reference to random memory and/or a segfault. There were also some
158        other cases where backtracking after \C could crash. This set of bugs was
159        discovered by the LLVM fuzzer.
161    20. The function for finding the minimum length of a matching string could take
162        a very long time if mutual recursion was present many times in a pattern,
163        for example, /((?2){73}(?2))((?1))/. A better mutual recursion detection
164        method has been implemented. This infelicity was discovered by the LLVM
165        fuzzer.
168    Version 8.36 26-September-2014
169    ------------------------------
171    1.  Got rid of some compiler warnings in the C++ modules that were shown up by
172        -Wmissing-field-initializers and -Wunused-parameter.
174    2.  The tests for quantifiers being too big (greater than 65535) were being
175        applied after reading the number, and stupidly assuming that integer
176        overflow would give a negative number. The tests are now applied as the
177        numbers are read.
179    3.  Tidy code in pcre_exec.c where two branches that used to be different are
180        now the same.
182    4.  The JIT compiler did not generate match limit checks for certain
183        bracketed expressions with quantifiers. This may lead to exponential
184        backtracking, instead of returning with PCRE_ERROR_MATCHLIMIT. This
185        issue should be resolved now.
187    5.  Fixed an issue, which occures when nested alternatives are optimized
188        with table jumps.
190    6.  Inserted two casts and changed some ints to size_t in the light of some
191        reported 64-bit compiler warnings (Bugzilla 1477).
193    7.  Fixed a bug concerned with zero-minimum possessive groups that could match
194        an empty string, which sometimes were behaving incorrectly in the
195        interpreter (though correctly in the JIT matcher). This pcretest input is
196        an example:
198          '\A(?:[^"]++|"(?:[^"]*+|"")*+")++'
201        the interpreter was reporting a match of 'NON QUOTED ' only, whereas the
202        JIT matcher and Perl both matched 'NON QUOTED "QUOT""ED" AFTER '. The test
203        for an empty string was breaking the inner loop and carrying on at a lower
204        level, when possessive repeated groups should always return to a higher
205        level as they have no backtrack points in them. The empty string test now
206        occurs at the outer level.
208    8.  Fixed a bug that was incorrectly auto-possessifying \w+ in the pattern
209        ^\w+(?>\s*)(?<=\w) which caused it not to match "test test".
211    9.  Give a compile-time error for \o{} (as Perl does) and for \x{} (which Perl
212        doesn't).
214    10. Change 8.34/15 introduced a bug that caused the amount of memory needed
215        to hold a pattern to be incorrectly computed (too small) when there were
216        named back references to duplicated names. This could cause "internal
217        error: code overflow" or "double free or corruption" or other memory
218        handling errors.
220    11. When named subpatterns had the same prefixes, back references could be
221        confused. For example, in this pattern:
223          /(?P<Name>a)?(?P<Name2>b)?(?(<Name>)c|d)*l/
225        the reference to 'Name' was incorrectly treated as a reference to a
226        duplicate name.
228    12. A pattern such as /^s?c/mi8 where the optional character has more than
229        one "other case" was incorrectly compiled such that it would only try to
230        match starting at "c".
232    13. When a pattern starting with \s was studied, VT was not included in the
233        list of possible starting characters; this should have been part of the
234        8.34/18 patch.
236    14. If a character class started [\Qx]... where x is any character, the class
237        was incorrectly terminated at the ].
239    15. If a pattern that started with a caseless match for a character with more
240        than one "other case" was studied, PCRE did not set up the starting code
241        unit bit map for the list of possible characters. Now it does. This is an
242        optimization improvement, not a bug fix.
244    16. The Unicode data tables have been updated to Unicode 7.0.0.
246    17. Fixed a number of memory leaks in pcregrep.
248    18. Avoid a compiler warning (from some compilers) for a function call with
249        a cast that removes "const" from an lvalue by using an intermediate
250        variable (to which the compiler does not object).
252    19. Incorrect code was compiled if a group that contained an internal recursive
253        back reference was optional (had quantifier with a minimum of zero). This
254        example compiled incorrect code: /(((a\2)|(a*)\g<-1>))*/ and other examples
255        caused segmentation faults because of stack overflows at compile time.
257    20. A pattern such as /((?(R)a|(?1)))+/, which contains a recursion within a
258        group that is quantified with an indefinite repeat, caused a compile-time
259        loop which used up all the system stack and provoked a segmentation fault.
260        This was not the same bug as 19 above.
262    21. Add PCRECPP_EXP_DECL declaration to operator<< in pcre_stringpiece.h.
263        Patch by Mike Frysinger.
266    Version 8.35 04-April-2014
267    --------------------------
269    1.  A new flag is set, when property checks are present in an XCLASS.
270        When this flag is not set, PCRE can perform certain optimizations
271        such as studying these XCLASS-es.
273    2.  The auto-possessification of character sets were improved: a normal
274        and an extended character set can be compared now. Furthermore
275        the JIT compiler optimizes more character set checks.
277    3.  Got rid of some compiler warnings for potentially uninitialized variables
278        that show up only when compiled with -O2.
280    4.  A pattern such as (?=ab\K) that uses \K in an assertion can set the start
281        of a match later then the end of the match. The pcretest program was not
282        handling the case sensibly - it was outputting from the start to the next
283        binary zero. It now reports this situation in a message, and outputs the
284        text from the end to the start.
286    5.  Fast forward search is improved in JIT. Instead of the first three
287        characters, any three characters with fixed position can be searched.
288        Search order: first, last, middle.
290    6.  Improve character range checks in JIT. Characters are read by an inprecise
291        function now, which returns with an unknown value if the character code is
292        above a certain threshold (e.g: 256). The only limitation is that the value
293        must be bigger than the threshold as well. This function is useful when
294        the characters above the threshold are handled in the same way.
296    7.  The macros whose names start with RAWUCHAR are placeholders for a future
297        mode in which only the bottom 21 bits of 32-bit data items are used. To
298        make this more memorable for those maintaining the code, the names have
299        been changed to start with UCHAR21, and an extensive comment has been added
300        to their definition.
302    8.  Add missing (new) files sljitNativeTILEGX.c and sljitNativeTILEGX-encoder.c
303        to the export list in Makefile.am (they were accidentally omitted from the
304        8.34 tarball).
306    9.  The informational output from pcretest used the phrase "starting byte set"
307        which is inappropriate for the 16-bit and 32-bit libraries. As the output
308        for "first char" and "need char" really means "non-UTF-char", I've changed
309        "byte" to "char", and slightly reworded the output. The documentation about
310        these values has also been (I hope) clarified.
312    10. Another JIT related optimization: use table jumps for selecting the correct
313        backtracking path, when more than four alternatives are present inside a
314        bracket.
316    11. Empty match is not possible, when the minimum length is greater than zero,
317        and there is no \K in the pattern. JIT should avoid empty match checks in
318        such cases.
320    12. In a caseless character class with UCP support, when a character with more
321        than one alternative case was not the first character of a range, not all
322        the alternative cases were added to the class. For example, s and \x{17f}
323        are both alternative cases for S: the class [RST] was handled correctly,
324        but [R-T] was not.
326    13. The configure.ac file always checked for pthread support when JIT was
327        enabled. This is not used in Windows, so I have put this test inside a
328        check for the presence of windows.h (which was already tested for).
330    14. Improve pattern prefix search by a simplified Boyer-Moore algorithm in JIT.
331        The algorithm provides a way to skip certain starting offsets, and usually
332        faster than linear prefix searches.
334    15. Change 13 for 8.20 updated RunTest to check for the 'fr' locale as well
335        as for 'fr_FR' and 'french'. For some reason, however, it then used the
336        Windows-specific input and output files, which have 'french' screwed in.
337        So this could never have worked. One of the problems with locales is that
338        they aren't always the same. I have now updated RunTest so that it checks
339        the output of the locale test (test 3) against three different output
340        files, and it allows the test to pass if any one of them matches. With luck
341        this should make the test pass on some versions of Solaris where it was
342        failing. Because of the uncertainty, the script did not used to stop if
343        test 3 failed; it now does. If further versions of a French locale ever
344        come to light, they can now easily be added.
346    16. If --with-pcregrep-bufsize was given a non-integer value such as "50K",
347        there was a message during ./configure, but it did not stop. This now
348        provokes an error. The invalid example in README has been corrected.
349        If a value less than the minimum is given, the minimum value has always
350        been used, but now a warning is given.
352    17. If --enable-bsr-anycrlf was set, the special 16/32-bit test failed. This
353        was a bug in the test system, which is now fixed. Also, the list of various
354        configurations that are tested for each release did not have one with both
355        16/32 bits and --enable-bar-anycrlf. It now does.
357    18. pcretest was missing "-C bsr" for displaying the \R default setting.
359    19. Little endian PowerPC systems are supported now by the JIT compiler.
361    20. The fast forward newline mechanism could enter to an infinite loop on
362        certain invalid UTF-8 input. Although we don't support these cases
363        this issue can be fixed by a performance optimization.
365    21. Change 33 of 8.34 is not sufficient to ensure stack safety because it does
366        not take account if existing stack usage. There is now a new global
367        variable called pcre_stack_guard that can be set to point to an external
368        function to check stack availability. It is called at the start of
369        processing every parenthesized group.
371    22. A typo in the code meant that in ungreedy mode the max/min qualifier
372        behaved like a min-possessive qualifier, and, for example, /a{1,3}b/U did
373        not match "ab".
375    23. When UTF was disabled, the JIT program reported some incorrect compile
376        errors. These messages are silenced now.
378    24. Experimental support for ARM-64 and MIPS-64 has been added to the JIT
379        compiler.
381    25. Change all the temporary files used in RunGrepTest to be different to those
382        used by RunTest so that the tests can be run simultaneously, for example by
383        "make -j check".
386    Version 8.34 15-December-2013
387    -----------------------------
389    1.  Add pcre[16|32]_jit_free_unused_memory to forcibly free unused JIT
390        executable memory. Patch inspired by Carsten Klein.
392    2.  ./configure --enable-coverage defined SUPPORT_GCOV in config.h, although
393        this macro is never tested and has no effect, because the work to support
394        coverage involves only compiling and linking options and special targets in
395        the Makefile. The comment in config.h implied that defining the macro would
396        enable coverage support, which is totally false. There was also support for
397        setting this macro in the CMake files (my fault, I just copied it from
398        configure). SUPPORT_GCOV has now been removed.
400    3.  Make a small performance improvement in strlen16() and strlen32() in
401        pcretest.
403    4.  Change 36 for 8.33 left some unreachable statements in pcre_exec.c,
404        detected by the Solaris compiler (gcc doesn't seem to be able to diagnose
405        these cases). There was also one in pcretest.c.
407    5.  Cleaned up a "may be uninitialized" compiler warning in pcre_exec.c.
409    6.  In UTF mode, the code for checking whether a group could match an empty
410        string (which is used for indefinitely repeated groups to allow for
411        breaking an infinite loop) was broken when the group contained a repeated
412        negated single-character class with a character that occupied more than one
413        data item and had a minimum repetition of zero (for example, [^\x{100}]* in
414        UTF-8 mode). The effect was undefined: the group might or might not be
415        deemed as matching an empty string, or the program might have crashed.
417    7.  The code for checking whether a group could match an empty string was not
418        recognizing that \h, \H, \v, \V, and \R must match a character.
420    8.  Implemented PCRE_INFO_MATCH_EMPTY, which yields 1 if the pattern can match
421        an empty string. If it can, pcretest shows this in its information output.
423    9.  Fixed two related bugs that applied to Unicode extended grapheme clusters
424        that were repeated with a maximizing qualifier (e.g. \X* or \X{2,5}) when
425        matched by pcre_exec() without using JIT:
427        (a) If the rest of the pattern did not match after a maximal run of
428            grapheme clusters, the code for backing up to try with fewer of them
429            did not always back up over a full grapheme when characters that do not
430            have the modifier quality were involved, e.g. Hangul syllables.
432        (b) If the match point in a subject started with modifier character, and
433            there was no match, the code could incorrectly back up beyond the match
434            point, and potentially beyond the first character in the subject,
435            leading to a segfault or an incorrect match result.
437    10. A conditional group with an assertion condition could lead to PCRE
438        recording an incorrect first data item for a match if no other first data
439        item was recorded. For example, the pattern (?(?=ab)ab) recorded "a" as a
440        first data item, and therefore matched "ca" after "c" instead of at the
441        start.
443    11. Change 40 for 8.33 (allowing pcregrep to find empty strings) showed up a
444        bug that caused the command "echo a | ./pcregrep -M '|a'" to loop.
446    12. The source of pcregrep now includes z/OS-specific code so that it can be
447        compiled for z/OS as part of the special z/OS distribution.
449    13. Added the -T and -TM options to pcretest.
451    14. The code in pcre_compile.c for creating the table of named capturing groups
452        has been refactored. Instead of creating the table dynamically during the
453        actual compiling pass, the information is remembered during the pre-compile
454        pass (on the stack unless there are more than 20 named groups, in which
455        case malloc() is used) and the whole table is created before the actual
456        compile happens. This has simplified the code (it is now nearly 150 lines
457        shorter) and prepared the way for better handling of references to groups
458        with duplicate names.
460    15. A back reference to a named subpattern when there is more than one of the
461        same name now checks them in the order in which they appear in the pattern.
462        The first one that is set is used for the reference. Previously only the
463        first one was inspected. This change makes PCRE more compatible with Perl.
465    16. Unicode character properties were updated from Unicode 6.3.0.
467    17. The compile-time code for auto-possessification has been refactored, based
468        on a patch by Zoltan Herczeg. It now happens after instead of during
469        compilation. The code is cleaner, and more cases are handled. The option
470        PCRE_NO_AUTO_POSSESS is added for testing purposes, and the -O and /O
471        options in pcretest are provided to set it. It can also be set by
472        (*NO_AUTO_POSSESS) at the start of a pattern.
474    18. The character VT has been added to the default ("C" locale) set of
475        characters that match \s and are generally treated as white space,
476        following this same change in Perl 5.18. There is now no difference between
477        "Perl space" and "POSIX space". Whether VT is treated as white space in
478        other locales depends on the locale.
480    19. The code for checking named groups as conditions, either for being set or
481        for being recursed, has been refactored (this is related to 14 and 15
482        above). Processing unduplicated named groups should now be as fast at
483        numerical groups, and processing duplicated groups should be faster than
484        before.
486    20. Two patches to the CMake build system, by Alexander Barkov:
488          (1) Replace the "source" command by "." in CMakeLists.txt because
489              "source" is a bash-ism.
491          (2) Add missing HAVE_STDINT_H and HAVE_INTTYPES_H to config-cmake.h.in;
492              without these the CMake build does not work on Solaris.
494    21. Perl has changed its handling of \8 and \9. If there is no previously
495        encountered capturing group of those numbers, they are treated as the
496        literal characters 8 and 9 instead of a binary zero followed by the
497        literals. PCRE now does the same.
499    22. Following Perl, added \o{} to specify codepoints in octal, making it
500        possible to specify values greater than 0777 and also making them
501        unambiguous.
503    23. Perl now gives an error for missing closing braces after \x{... instead of
504        treating the string as literal. PCRE now does the same.
506    24. RunTest used to grumble if an inappropriate test was selected explicitly,
507        but just skip it when running all tests. This make it awkward to run ranges
508        of tests when one of them was inappropriate. Now it just skips any
509        inappropriate tests, as it always did when running all tests.
511    25. If PCRE_AUTO_CALLOUT and PCRE_UCP were set for a pattern that contained
512        character types such as \d or \w, too many callouts were inserted, and the
513        data that they returned was rubbish.
515    26. In UCP mode, \s was not matching two of the characters that Perl matches,
516        namely NEL (U+0085) and MONGOLIAN VOWEL SEPARATOR (U+180E), though they
517        were matched by \h. The code has now been refactored so that the lists of
518        the horizontal and vertical whitespace characters used for \h and \v (which
519        are defined only in one place) are now also used for \s.
521    27. Add JIT support for the 64 bit TileGX architecture.
522        Patch by Jiong Wang (Tilera Corporation).
524    28. Possessive quantifiers for classes (both explicit and automatically
525        generated) now use special opcodes instead of wrapping in ONCE brackets.
527    29. Whereas an item such as A{4}+ ignored the possessivenes of the quantifier
528        (because it's meaningless), this was not happening when PCRE_CASELESS was
529        set. Not wrong, but inefficient.
531    30. Updated perltest.pl to add /u (force Unicode mode) when /W (use Unicode
532        properties for \w, \d, etc) is present in a test regex. Otherwise if the
533        test contains no characters greater than 255, Perl doesn't realise it
534        should be using Unicode semantics.
536    31. Upgraded the handling of the POSIX classes [:graph:], [:print:], and
537        [:punct:] when PCRE_UCP is set so as to include the same characters as Perl
538        does in Unicode mode.
540    32. Added the "forbid" facility to pcretest so that putting tests into the
541        wrong test files can sometimes be quickly detected.
543    33. There is now a limit (default 250) on the depth of nesting of parentheses.
544        This limit is imposed to control the amount of system stack used at compile
545        time. It can be changed at build time by --with-parens-nest-limit=xxx or
546        the equivalent in CMake.
548    34. Character classes such as [A-\d] or [a-[:digit:]] now cause compile-time
549        errors. Perl warns for these when in warning mode, but PCRE has no facility
550        for giving warnings.
552    35. Change 34 for 8.13 allowed quantifiers on assertions, because Perl does.
553        However, this was not working for (?!) because it is optimized to (*FAIL),
554        for which PCRE does not allow quantifiers. The optimization is now disabled
555        when a quantifier follows (?!). I can't see any use for this, but it makes
556        things uniform.
558    36. Perl no longer allows group names to start with digits, so I have made this
559        change also in PCRE. It simplifies the code a bit.
561    37. In extended mode, Perl ignores spaces before a + that indicates a
562        possessive quantifier. PCRE allowed a space before the quantifier, but not
563        before the possessive +. It now does.
565    38. The use of \K (reset reported match start) within a repeated possessive
566        group such as (a\Kb)*+ was not working.
568    40. Document that the same character tables must be used at compile time and
569        run time, and that the facility to pass tables to pcre_exec() and
570        pcre_dfa_exec() is for use only with saved/restored patterns.
572    41. Applied Jeff Trawick's patch CMakeLists.txt, which "provides two new
573        features for Builds with MSVC:
575        1. Support pcre.rc and/or pcreposix.rc (as is already done for MinGW
576           builds). The .rc files can be used to set FileDescription and many other
577           attributes.
579        2. Add an option (-DINSTALL_MSVC_PDB) to enable installation of .pdb files.
580           This allows higher-level build scripts which want .pdb files to avoid
581           hard-coding the exact files needed."
583    42. Added support for [[:<:]] and [[:>:]] as used in the BSD POSIX library to
584        mean "start of word" and "end of word", respectively, as a transition aid.
586    43. A minimizing repeat of a class containing codepoints greater than 255 in
587        non-UTF 16-bit or 32-bit modes caused an internal error when PCRE was
588        compiled to use the heap for recursion.
590    44. Got rid of some compiler warnings for unused variables when UTF but not UCP
591        is configured.
594    Version 8.33 28-May-2013
595    ------------------------
597    1.  Added 'U' to some constants that are compared to unsigned integers, to
598        avoid compiler signed/unsigned warnings. Added (int) casts to unsigned
599        variables that are added to signed variables, to ensure the result is
600        signed and can be negated.
602    2.  Applied patch by Daniel Richard G for quashing MSVC warnings to the
603        CMake config files.
605    3.  Revise the creation of config.h.generic so that all boolean macros are
606        #undefined, whereas non-boolean macros are #ifndef/#endif-ed. This makes
607        overriding via -D on the command line possible.
609    4.  Changing the definition of the variable "op" in pcre_exec.c from pcre_uchar
610        to unsigned int is reported to make a quite noticeable speed difference in
611        a specific Windows environment. Testing on Linux did also appear to show
612        some benefit (and it is clearly not harmful). Also fixed the definition of
613        Xop which should be unsigned.
615    5.  Related to (4), changing the definition of the intermediate variable cc
616        in repeated character loops from pcre_uchar to pcre_uint32 also gave speed
617        improvements.
619    6.  Fix forward search in JIT when link size is 3 or greater. Also removed some
620        unnecessary spaces.
622    7.  Adjust autogen.sh and configure.ac to lose warnings given by automake 1.12
623        and later.
625    8.  Fix two buffer over read issues in 16 and 32 bit modes. Affects JIT only.
627    9.  Optimizing fast_forward_start_bits in JIT.
629    10. Adding support for callouts in JIT, and fixing some issues revealed
630        during this work. Namely:
632        (a) Unoptimized capturing brackets incorrectly reset on backtrack.
634        (b) Minimum length was not checked before the matching is started.
636    11. The value of capture_last that is passed to callouts was incorrect in some
637        cases when there was a capture on one path that was subsequently abandoned
638        after a backtrack. Also, the capture_last value is now reset after a
639        recursion, since all captures are also reset in this case.
641    12. The interpreter no longer returns the "too many substrings" error in the
642        case when an overflowing capture is in a branch that is subsequently
643        abandoned after a backtrack.
645    13. In the pathological case when an offset vector of size 2 is used, pcretest
646        now prints out the matched string after a yield of 0 or 1.
648    14. Inlining subpatterns in recursions, when certain conditions are fulfilled.
649        Only supported by the JIT compiler at the moment.
651    15. JIT compiler now supports 32 bit Macs thanks to Lawrence Velazquez.
653    16. Partial matches now set offsets[2] to the "bumpalong" value, that is, the
654        offset of the starting point of the matching process, provided the offsets
655        vector is large enough.
657    17. The \A escape now records a lookbehind value of 1, though its execution
658        does not actually inspect the previous character. This is to ensure that,
659        in partial multi-segment matching, at least one character from the old
660        segment is retained when a new segment is processed. Otherwise, if there
661        are no lookbehinds in the pattern, \A might match incorrectly at the start
662        of a new segment.
664    18. Added some #ifdef __VMS code into pcretest.c to help VMS implementations.
666    19. Redefined some pcre_uchar variables in pcre_exec.c as pcre_uint32; this
667        gives some modest performance improvement in 8-bit mode.
669    20. Added the PCRE-specific property \p{Xuc} for matching characters that can
670        be expressed in certain programming languages using Universal Character
671        Names.
673    21. Unicode validation has been updated in the light of Unicode Corrigendum #9,
674        which points out that "non characters" are not "characters that may not
675        appear in Unicode strings" but rather "characters that are reserved for
676        internal use and have only local meaning".
678    22. When a pattern was compiled with automatic callouts (PCRE_AUTO_CALLOUT) and
679        there was a conditional group that depended on an assertion, if the
680        assertion was false, the callout that immediately followed the alternation
681        in the condition was skipped when pcre_exec() was used for matching.
683    23. Allow an explicit callout to be inserted before an assertion that is the
684        condition for a conditional group, for compatibility with automatic
685        callouts, which always insert a callout at this point.
687    24. In 8.31, (*COMMIT) was confined to within a recursive subpattern. Perl also
688        confines (*SKIP) and (*PRUNE) in the same way, and this has now been done.
690    25. (*PRUNE) is now supported by the JIT compiler.
692    26. Fix infinite loop when /(?<=(*SKIP)ac)a/ is matched against aa.
694    27. Fix the case where there are two or more SKIPs with arguments that may be
695        ignored.
697    28. (*SKIP) is now supported by the JIT compiler.
699    29. (*THEN) is now supported by the JIT compiler.
701    30. Update RunTest with additional test selector options.
703    31. The way PCRE handles backtracking verbs has been changed in two ways.
705        (1) Previously, in something like (*COMMIT)(*SKIP), COMMIT would override
706        SKIP. Now, PCRE acts on whichever backtracking verb is reached first by
707        backtracking. In some cases this makes it more Perl-compatible, but Perl's
708        rather obscure rules do not always do the same thing.
710        (2) Previously, backtracking verbs were confined within assertions. This is
711        no longer the case for positive assertions, except for (*ACCEPT). Again,
712        this sometimes improves Perl compatibility, and sometimes does not.
714    32. A number of tests that were in test 2 because Perl did things differently
715        have been moved to test 1, because either Perl or PCRE has changed, and
716        these tests are now compatible.
718    32. Backtracking control verbs are now handled in the same way in JIT and
719        interpreter.
721    33. An opening parenthesis in a MARK/PRUNE/SKIP/THEN name in a pattern that
722        contained a forward subroutine reference caused a compile error.
724    34. Auto-detect and optimize limited repetitions in JIT.
726    35. Implement PCRE_NEVER_UTF to lock out the use of UTF, in particular,
727        blocking (*UTF) etc.
729    36. In the interpreter, maximizing pattern repetitions for characters and
730        character types now use tail recursion, which reduces stack usage.
732    37. The value of the max lookbehind was not correctly preserved if a compiled
733        and saved regex was reloaded on a host of different endianness.
735    38. Implemented (*LIMIT_MATCH) and (*LIMIT_RECURSION). As part of the extension
736        of the compiled pattern block, expand the flags field from 16 to 32 bits
737        because it was almost full.
739    39. Try madvise first before posix_madvise.
741    40. Change 7 for PCRE 7.9 made it impossible for pcregrep to find empty lines
742        with a pattern such as ^$. It has taken 4 years for anybody to notice! The
743        original change locked out all matches of empty strings. This has been
744        changed so that one match of an empty string per line is recognized.
745        Subsequent searches on the same line (for colouring or for --only-matching,
746        for example) do not recognize empty strings.
748    41. Applied a user patch to fix a number of spelling mistakes in comments.
750    42. Data lines longer than 65536 caused pcretest to crash.
752    43. Clarified the data type for length and startoffset arguments for pcre_exec
753        and pcre_dfa_exec in the function-specific man pages, where they were
754        explicitly stated to be in bytes, never having been updated. I also added
755        some clarification to the pcreapi man page.
757    44. A call to pcre_dfa_exec() with an output vector size less than 2 caused
758        a segmentation fault.
761    Version 8.32 30-November-2012
762    -----------------------------
764    1.  Improved JIT compiler optimizations for first character search and single
765        character iterators.
767    2.  Supporting IBM XL C compilers for PPC architectures in the JIT compiler.
768        Patch by Daniel Richard G.
770    3.  Single character iterator optimizations in the JIT compiler.
772    4.  Improved JIT compiler optimizations for character ranges.
774    5.  Rename the "leave" variable names to "quit" to improve WinCE compatibility.
775        Reported by Giuseppe D'Angelo.
777    6.  The PCRE_STARTLINE bit, indicating that a match can occur only at the start
778        of a line, was being set incorrectly in cases where .* appeared inside
779        atomic brackets at the start of a pattern, or where there was a subsequent
780        *PRUNE or *SKIP.
782    7.  Improved instruction cache flush for POWER/PowerPC.
783        Patch by Daniel Richard G.
785    8.  Fixed a number of issues in pcregrep, making it more compatible with GNU
786        grep:
788        (a) There is now no limit to the number of patterns to be matched.
790        (b) An error is given if a pattern is too long.
792        (c) Multiple uses of --exclude, --exclude-dir, --include, and --include-dir
793            are now supported.
795        (d) --exclude-from and --include-from (multiple use) have been added.
797        (e) Exclusions and inclusions now apply to all files and directories, not
798            just to those obtained from scanning a directory recursively.
800        (f) Multiple uses of -f and --file-list are now supported.
802        (g) In a Windows environment, the default for -d has been changed from
803            "read" (the GNU grep default) to "skip", because otherwise the presence
804            of a directory in the file list provokes an error.
806        (h) The documentation has been revised and clarified in places.
808    9.  Improve the matching speed of capturing brackets.
810    10. Changed the meaning of \X so that it now matches a Unicode extended
811        grapheme cluster.
813    11. Patch by Daniel Richard G to the autoconf files to add a macro for sorting
814        out POSIX threads when JIT support is configured.
816    12. Added support for PCRE_STUDY_EXTRA_NEEDED.
818    13. In the POSIX wrapper regcomp() function, setting re_nsub field in the preg
819        structure could go wrong in environments where size_t is not the same size
820        as int.
822    14. Applied user-supplied patch to pcrecpp.cc to allow PCRE_NO_UTF8_CHECK to be
823        set.
825    15. The EBCDIC support had decayed; later updates to the code had included
826        explicit references to (e.g.) \x0a instead of CHAR_LF. There has been a
827        general tidy up of EBCDIC-related issues, and the documentation was also
828        not quite right. There is now a test that can be run on ASCII systems to
829        check some of the EBCDIC-related things (but is it not a full test).
831    16. The new PCRE_STUDY_EXTRA_NEEDED option is now used by pcregrep, resulting
832        in a small tidy to the code.
834    17. Fix JIT tests when UTF is disabled and both 8 and 16 bit mode are enabled.
836    18. If the --only-matching (-o) option in pcregrep is specified multiple
837        times, each one causes appropriate output. For example, -o1 -o2 outputs the
838        substrings matched by the 1st and 2nd capturing parentheses. A separating
839        string can be specified by --om-separator (default empty).
841    19. Improving the first n character searches.
843    20. Turn case lists for horizontal and vertical white space into macros so that
844        they are defined only once.
846    21. This set of changes together give more compatible Unicode case-folding
847        behaviour for characters that have more than one other case when UCP
848        support is available.
850        (a) The Unicode property table now has offsets into a new table of sets of
851            three or more characters that are case-equivalent. The MultiStage2.py
852            script that generates these tables (the pcre_ucd.c file) now scans
853            CaseFolding.txt instead of UnicodeData.txt for character case
854            information.
856        (b) The code for adding characters or ranges of characters to a character
857            class has been abstracted into a generalized function that also handles
858            case-independence. In UTF-mode with UCP support, this uses the new data
859            to handle characters with more than one other case.
861        (c) A bug that is fixed as a result of (b) is that codepoints less than 256
862            whose other case is greater than 256 are now correctly matched
863            caselessly. Previously, the high codepoint matched the low one, but not
864            vice versa.
866        (d) The processing of \h, \H, \v, and \ in character classes now makes use
867            of the new class addition function, using character lists defined as
868            macros alongside the case definitions of 20 above.
870        (e) Caseless back references now work with characters that have more than
871            one other case.
873        (f) General caseless matching of characters with more than one other case
874            is supported.
876    22. Unicode character properties were updated from Unicode 6.2.0
878    23. Improved CMake support under Windows. Patch by Daniel Richard G.
880    24. Add support for 32-bit character strings, and UTF-32
882    25. Major JIT compiler update (code refactoring and bugfixing).
883        Experimental Sparc 32 support is added.
885    26. Applied a modified version of Daniel Richard G's patch to create
886        pcre.h.generic and config.h.generic by "make" instead of in the
887        PrepareRelease script.
889    27. Added a definition for CHAR_NULL (helpful for the z/OS port), and use it in
890        pcre_compile.c when checking for a zero character.
892    28. Introducing a native interface for JIT. Through this interface, the compiled
893        machine code can be directly executed. The purpose of this interface is to
894        provide fast pattern matching, so several sanity checks are not performed.
895        However, feature tests are still performed. The new interface provides
896        1.4x speedup compared to the old one.
898    29. If pcre_exec() or pcre_dfa_exec() was called with a negative value for
899        the subject string length, the error given was PCRE_ERROR_BADOFFSET, which
900        was confusing. There is now a new error PCRE_ERROR_BADLENGTH for this case.
902    30. In 8-bit UTF-8 mode, pcretest failed to give an error for data codepoints
903        greater than 0x7fffffff (which cannot be represented in UTF-8, even under
904        the "old" RFC 2279). Instead, it ended up passing a negative length to
905        pcre_exec().
907    31. Add support for GCC's visibility feature to hide internal functions.
909    32. Running "pcretest -C pcre8" or "pcretest -C pcre16" gave a spurious error
910        "unknown -C option" after outputting 0 or 1.
912    33. There is now support for generating a code coverage report for the test
913        suite in environments where gcc is the compiler and lcov is installed. This
914        is mainly for the benefit of the developers.
916    34. If PCRE is built with --enable-valgrind, certain memory regions are marked
917        unaddressable using valgrind annotations, allowing valgrind to detect
918        invalid memory accesses. This is mainly for the benefit of the developers.
920    25. (*UTF) can now be used to start a pattern in any of the three libraries.
922    26. Give configure error if --enable-cpp but no C++ compiler found.
925    Version 8.31 06-July-2012
926    -------------------------
928    1.  Fixing a wrong JIT test case and some compiler warnings.
930    2.  Removed a bashism from the RunTest script.
932    3.  Add a cast to pcre_exec.c to fix the warning "unary minus operator applied
933        to unsigned type, result still unsigned" that was given by an MS compiler
934        on encountering the code "-sizeof(xxx)".
936    4.  Partial matching support is added to the JIT compiler.
938    5.  Fixed several bugs concerned with partial matching of items that consist
939        of more than one character:
941        (a) /^(..)\1/ did not partially match "aba" because checking references was
942            done on an "all or nothing" basis. This also applied to repeated
943            references.
945        (b) \R did not give a hard partial match if \r was found at the end of the
946            subject.
948        (c) \X did not give a hard partial match after matching one or more
949            characters at the end of the subject.
951        (d) When newline was set to CRLF, a pattern such as /a$/ did not recognize
952            a partial match for the string "\r".
954        (e) When newline was set to CRLF, the metacharacter "." did not recognize
955            a partial match for a CR character at the end of the subject string.
957    6.  If JIT is requested using /S++ or -s++ (instead of just /S+ or -s+) when
958        running pcretest, the text "(JIT)" added to the output whenever JIT is
959        actually used to run the match.
961    7.  Individual JIT compile options can be set in pcretest by following -s+[+]
962        or /S+[+] with a digit between 1 and 7.
964    8.  OP_NOT now supports any UTF character not just single-byte ones.
966    9.  (*MARK) control verb is now supported by the JIT compiler.
968    10. The command "./RunTest list" lists the available tests without actually
969        running any of them. (Because I keep forgetting what they all are.)
973    12. Applied a (slightly modified) user-supplied patch that improves performance
974        when the heap is used for recursion (compiled with --disable-stack-for-
975        recursion). Instead of malloc and free for each heap frame each time a
976        logical recursion happens, frames are retained on a chain and re-used where
977        possible. This sometimes gives as much as 30% improvement.
979    13. As documented, (*COMMIT) is now confined to within a recursive subpattern
980        call.
982    14. As documented, (*COMMIT) is now confined to within a positive assertion.
984    15. It is now possible to link pcretest with libedit as an alternative to
985        libreadline.
987    16. (*COMMIT) control verb is now supported by the JIT compiler.
989    17. The Unicode data tables have been updated to Unicode 6.1.0.
991    18. Added --file-list option to pcregrep.
993    19. Added binary file support to pcregrep, including the -a, --binary-files,
994        -I, and --text options.
996    20. The madvise function is renamed for posix_madvise for QNX compatibility
997        reasons. Fixed by Giuseppe D'Angelo.
999    21. Fixed a bug for backward assertions with REVERSE 0 in the JIT compiler.
1001    22. Changed the option for creating symbolic links for 16-bit man pages from
1002        -s to -sf so that re-installing does not cause issues.
1004    23. Support PCRE_NO_START_OPTIMIZE in JIT as (*MARK) support requires it.
1006    24. Fixed a very old bug in pcretest that caused errors with restarted DFA
1007        matches in certain environments (the workspace was not being correctly
1008        retained). Also added to pcre_dfa_exec() a simple plausibility check on
1009        some of the workspace data at the beginning of a restart.
1011    25. \s*\R was auto-possessifying the \s* when it should not, whereas \S*\R
1012        was not doing so when it should - probably a typo introduced by SVN 528
1013        (change 8.10/14).
1015    26. When PCRE_UCP was not set, \w+\x{c4} was incorrectly auto-possessifying the
1016        \w+ when the character tables indicated that \x{c4} was a word character.
1017        There were several related cases, all because the tests for doing a table
1018        lookup were testing for characters less than 127 instead of 255.
1020    27. If a pattern contains capturing parentheses that are not used in a match,
1021        their slots in the ovector are set to -1. For those that are higher than
1022        any matched groups, this happens at the end of processing. In the case when
1023        there were back references that the ovector was too small to contain
1024        (causing temporary malloc'd memory to be used during matching), and the
1025        highest capturing number was not used, memory off the end of the ovector
1026        was incorrectly being set to -1. (It was using the size of the temporary
1027        memory instead of the true size.)
1029    28. To catch bugs like 27 using valgrind, when pcretest is asked to specify an
1030        ovector size, it uses memory at the end of the block that it has got.
1032    29. Check for an overlong MARK name and give an error at compile time. The
1033        limit is 255 for the 8-bit library and 65535 for the 16-bit library.
1035    30. JIT compiler update.
1037    31. JIT is now supported on jailbroken iOS devices. Thanks for Ruiger
1038        Rill for the patch.
1040    32. Put spaces around SLJIT_PRINT_D in the JIT compiler. Required by CXX11.
1042    33. Variable renamings in the PCRE-JIT compiler. No functionality change.
1044    34. Fixed typos in pcregrep: in two places there was SUPPORT_LIBZ2 instead of
1045        SUPPORT_LIBBZ2. This caused a build problem when bzip2 but not gzip (zlib)
1046        was enabled.
1048    35. Improve JIT code generation for greedy plus quantifier.
1050    36. When /((?:a?)*)*c/ or /((?>a?)*)*c/ was matched against "aac", it set group
1051        1 to "aa" instead of to an empty string. The bug affected repeated groups
1052        that could potentially match an empty string.
1054    37. Optimizing single character iterators in JIT.
1056    38. Wide characters specified with \uxxxx in JavaScript mode are now subject to
1057        the same checks as \x{...} characters in non-JavaScript mode. Specifically,
1058        codepoints that are too big for the mode are faulted, and in a UTF mode,
1059        disallowed codepoints are also faulted.
1061    39. If PCRE was compiled with UTF support, in three places in the DFA
1062        matcher there was code that should only have been obeyed in UTF mode, but
1063        was being obeyed unconditionally. In 8-bit mode this could cause incorrect
1064        processing when bytes with values greater than 127 were present. In 16-bit
1065        mode the bug would be provoked by values in the range 0xfc00 to 0xdc00. In
1066        both cases the values are those that cannot be the first data item in a UTF
1067        character. The three items that might have provoked this were recursions,
1068        possessively repeated groups, and atomic groups.
1070    40. Ensure that libpcre is explicitly listed in the link commands for pcretest
1071        and pcregrep, because some OS require shared objects to be explicitly
1072        passed to ld, causing the link step to fail if they are not.
1074    41. There were two incorrect #ifdefs in pcre_study.c, meaning that, in 16-bit
1075        mode, patterns that started with \h* or \R* might be incorrectly matched.
1078    Version 8.30 04-February-2012
1079    -----------------------------
1081    1.  Renamed "isnumber" as "is_a_number" because in some Mac environments this
1082        name is defined in ctype.h.
1084    2.  Fixed a bug in fixed-length calculation for lookbehinds that would show up
1085        only in quite long subpatterns.
1087    3.  Removed the function pcre_info(), which has been obsolete and deprecated
1088        since it was replaced by pcre_fullinfo() in February 2000.
1090    4.  For a non-anchored pattern, if (*SKIP) was given with a name that did not
1091        match a (*MARK), and the match failed at the start of the subject, a
1092        reference to memory before the start of the subject could occur. This bug
1093        was introduced by fix 17 of release 8.21.
1095    5.  A reference to an unset group with zero minimum repetition was giving
1096        totally wrong answers (in non-JavaScript-compatibility mode). For example,
1097        /(another)?(\1?)test/ matched against "hello world test". This bug was
1098        introduced in release 8.13.
1100    6.  Add support for 16-bit character strings (a large amount of work involving
1101        many changes and refactorings).
1103    7.  RunGrepTest failed on msys because \r\n was replaced by whitespace when the
1104        command "pattern=`printf 'xxx\r\njkl'`" was run. The pattern is now taken
1105        from a file.
1107    8.  Ovector size of 2 is also supported by JIT based pcre_exec (the ovector size
1108        rounding is not applied in this particular case).
1110    9.  The invalid Unicode surrogate codepoints U+D800 to U+DFFF are now rejected
1111        if they appear, or are escaped, in patterns.
1113    10. Get rid of a number of -Wunused-but-set-variable warnings.
1115    11. The pattern /(?=(*:x))(q|)/ matches an empty string, and returns the mark
1116        "x". The similar pattern /(?=(*:x))((*:y)q|)/ did not return a mark at all.
1117        Oddly, Perl behaves the same way. PCRE has been fixed so that this pattern
1118        also returns the mark "x". This bug applied to capturing parentheses,
1119        non-capturing parentheses, and atomic parentheses. It also applied to some
1120        assertions.
1122    12. Stephen Kelly's patch to CMakeLists.txt allows it to parse the version
1123        information out of configure.ac instead of relying on pcre.h.generic, which
1124        is not stored in the repository.
1126    13. Applied Dmitry V. Levin's patch for a more portable method for linking with
1127        -lreadline.
1129    14. ZH added PCRE_CONFIG_JITTARGET; added its output to pcretest -C.
1131    15. Applied Graycode's patch to put the top-level frame on the stack rather
1132        than the heap when not using the stack for recursion. This gives a
1133        performance improvement in many cases when recursion is not deep.
1135    16. Experimental code added to "pcretest -C" to output the stack frame size.
1138    Version 8.21 12-Dec-2011
1139    ------------------------
1141    1.  Updating the JIT compiler.
1143    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
1144        are added as well.
1146    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
1147        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
1148        calling _pcre_jit_exec. Some extra comments are added.
1150    4.  (*MARK) settings inside atomic groups that do not contain any capturing
1151        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
1152        was introduced by change 18 for 8.20.
1154    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
1155        ECMA-262 standard.
1157    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
1158        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
1159        This bug was probably introduced by change 9 of 8.13.
1161    7.  While fixing 6 above, I noticed that a number of other items were being
1162        incorrectly rejected as "not fixed length". This arose partly because newer
1163        opcodes had not been added to the fixed-length checking code. I have (a)
1164        corrected the bug and added tests for these items, and (b) arranged for an
1165        error to occur if an unknown opcode is encountered while checking for fixed
1166        length instead of just assuming "not fixed length". The items that were
1167        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
1168        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
1169        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
1171    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
1172        being incorrectly compiled and would have given unpredicatble results.
1174    9.  A possessively repeated subpattern with minimum repeat count greater than
1175        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
1176        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
1177        the first (A) could occur when it should not.
1179    10. Add a cast and remove a redundant test from the code.
1181    11. JIT should use pcre_malloc/pcre_free for allocation.
1183    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
1184        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
1185        is anything other than /usr, -L is still shown).
1187    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
1189    14. Perl does not support \N without a following name in a [] class; PCRE now
1190        also gives an error.
1192    15. If a forward reference was repeated with an upper limit of around 2000,
1193        it caused the error "internal error: overran compiling workspace". The
1194        maximum number of forward references (including repeats) was limited by the
1195        internal workspace, and dependent on the LINK_SIZE. The code has been
1196        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
1197        the default depends on LINK_SIZE. There is a new upper limit (for safety)
1198        of around 200,000 forward references. While doing this, I also speeded up
1199        the filling in of repeated forward references.
1201    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
1202        incorrectly expecting the subject to contain another "a" after the start.
1204    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
1205        in the match, the SKIP should be ignored. This was not happening; instead
1206        the SKIP was being treated as NOMATCH. For patterns such as
1207        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
1208        tested.
1210    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
1211        now much more compatible with Perl, in particular in cases where the result
1212        is a non-match for a non-anchored pattern. For example, if
1213        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
1214        "m", where previously it did not return a name. A side effect of this
1215        change is that for partial matches, the last encountered mark name is
1216        returned, as for non matches. A number of tests that were previously not
1217        Perl-compatible have been moved into the Perl-compatible test files. The
1218        refactoring has had the pleasing side effect of removing one argument from
1219        the match() function, thus reducing its stack requirements.
1221    19. If the /S+ option was used in pcretest to study a pattern using JIT,
1222        subsequent uses of /S (without +) incorrectly behaved like /S+.
1224    21. Retrieve executable code size support for the JIT compiler and fixing
1225        some warnings.
1227    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
1228        not work when the shorter character appeared right at the end of the
1229        subject string.
1231    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
1232        systems.
1234    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
1235        output it when the /M option is used in pcretest.
1237    25. The CheckMan script was not being included in the distribution. Also, added
1238        an explicit "perl" to run Perl scripts from the PrepareRelease script
1239        because this is reportedly needed in Windows.
1241    26. If study data was being save in a file and studying had not found a set of
1242        "starts with" bytes for the pattern, the data written to the file (though
1243        never used) was taken from uninitialized memory and so caused valgrind to
1244        complain.
1246    27. Updated RunTest.bat as provided by Sheri Pierce.
1248    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
1250    29. Computation of memory usage for the table of capturing group names was
1251        giving an unnecessarily large value.
1254    Version 8.20 21-Oct-2011
1255    ------------------------
1257    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
1258        a POSIX class. After further experiments with Perl, which convinced me that
1259        Perl has bugs and confusions, a closing square bracket is no longer allowed
1260        in a POSIX name. This bug also affected patterns with classes that started
1261        with full stops.
1263    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
1264        captured substring, but while checking the failing first alternative,
1265        substring 1 is temporarily captured. If the output vector supplied to
1266        pcre_exec() was not big enough for this capture, the yield of the function
1267        was still zero ("insufficient space for captured substrings"). This cannot
1268        be totally fixed without adding another stack variable, which seems a lot
1269        of expense for a edge case. However, I have improved the situation in cases
1270        such as /(a)(b)x|abc/ matched against "abc", where the return code
1271        indicates that fewer than the maximum number of slots in the ovector have
1272        been set.
1274    3.  Related to (2) above: when there are more back references in a pattern than
1275        slots in the output vector, pcre_exec() uses temporary memory during
1276        matching, and copies in the captures as far as possible afterwards. It was
1277        using the entire output vector, but this conflicts with the specification
1278        that only 2/3 is used for passing back captured substrings. Now it uses
1279        only the first 2/3, for compatibility. This is, of course, another edge
1280        case.
1282    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
1283        main code base, and can be used by building with --enable-jit. When this is
1284        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
1285        runtime --no-jit option is given.
1287    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
1288        ovector, the return from the function was zero, implying that there were
1289        other matches that did not fit. The correct "exactly full" value is now
1290        returned.
1292    6.  If a subpattern that was called recursively or as a subroutine contained
1293        (*PRUNE) or any other control that caused it to give a non-standard return,
1294        invalid errors such as "Error -26 (nested recursion at the same subject
1295        position)" or even infinite loops could occur.
1297    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
1298        computing the minimum length on reaching *ACCEPT, and so ended up with the
1299        wrong value of 1 rather than 0. Further investigation indicates that
1300        computing a minimum subject length in the presence of *ACCEPT is difficult
1301        (think back references, subroutine calls), and so I have changed the code
1302        so that no minimum is registered for a pattern that contains *ACCEPT.
1304    8.  If (*THEN) was present in the first (true) branch of a conditional group,
1305        it was not handled as intended. [But see 16 below.]
1307    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
1308        Sheri Pierce.
1310    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
1311        the first byte in a match must be "a".
1313    11. Change 17 for 8.13 increased the recursion depth for patterns like
1314        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
1315        pattern contains any instances of (*THEN). If it does not, the old
1316        optimizations are restored. It would be nice to do this on a per-group
1317        basis, but at the moment that is not feasible.
1319    12. In some environments, the output of pcretest -C is CRLF terminated. This
1320        broke RunTest's code that checks for the link size. A single white space
1321        character after the value is now allowed for.
1323    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
1324        For "fr", it uses the Windows-specific input and output files.
1326    14. If (*THEN) appeared in a group that was called recursively or as a
1327        subroutine, it did not work as intended. [But see next item.]
1329    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
1330        pattern fragments (but not containing any | characters). If A and B are
1331        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
1332        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
1333        D. In other words, Perl considers parentheses that do not contain any |
1334        characters to be part of a surrounding alternative, whereas PCRE was
1335        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
1336        differently. PCRE now behaves in the same way as Perl, except in the case
1337        of subroutine/recursion calls such as (?1) which have in any case always
1338        been different (but PCRE had them first :-).
1340    16. Related to 15 above: Perl does not treat the | in a conditional group as
1341        creating alternatives. Such a group is treated in the same way as an
1342        ordinary group without any | characters when processing (*THEN). PCRE has
1343        been changed to match Perl's behaviour.
1345    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
1346        RunGrepTest script failed.
1348    18. Change 22 for version 13 caused atomic groups to use more stack. This is
1349        inevitable for groups that contain captures, but it can lead to a lot of
1350        stack use in large patterns. The old behaviour has been restored for atomic
1351        groups that do not contain any capturing parentheses.
1353    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
1354        suppress the check for a minimum subject length at run time. (If it was
1355        given to pcre_exec() or pcre_dfa_exec() it did work.)
1357    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
1358        fail to work when decoding hex characters in data strings in EBCDIC
1359        environments.
1361    21. It appears that in at least one Mac OS environment, the isxdigit() function
1362        is implemented as a macro that evaluates to its argument more than once,
1363        contravening the C 90 Standard (I haven't checked a later standard). There
1364        was an instance in pcretest which caused it to go wrong when processing
1365        \x{...} escapes in subject strings. The has been rewritten to avoid using
1366        things like p++ in the argument of isxdigit().
1369    Version 8.13 16-Aug-2011
1370    ------------------------
1372    1.  The Unicode data tables have been updated to Unicode 6.0.0.
1374    2.  Two minor typos in pcre_internal.h have been fixed.
1376    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
1377        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
1378        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
1380    4.  There were a number of related bugs in the code for matching backrefences
1381        caselessly in UTF-8 mode when codes for the characters concerned were
1382        different numbers of bytes. For example, U+023A and U+2C65 are an upper
1383        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
1384        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
1385        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
1386        2-byte code at the end of the subject (it thought there wasn't enough data
1387        left).
1389    5.  Comprehensive information about what went wrong is now returned by
1390        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
1391        as the output vector has at least 2 elements. The offset of the start of
1392        the failing character and a reason code are placed in the vector.
1394    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
1395        now returned is for the first byte of the failing character, instead of the
1396        last byte inspected. This is an incompatible change, but I hope it is small
1397        enough not to be a problem. It makes the returned offset consistent with
1398        pcre_exec() and pcre_dfa_exec().
1400    7.  pcretest now gives a text phrase as well as the error number when
1401        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
1402        failure, the offset and reason code are output.
1404    8.  When \R was used with a maximizing quantifier it failed to skip backwards
1405        over a \r\n pair if the subsequent match failed. Instead, it just skipped
1406        back over a single character (\n). This seems wrong (because it treated the
1407        two characters as a single entity when going forwards), conflicts with the
1408        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
1409        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
1410        has been changed.
1412    9.  Some internal refactoring has changed the processing so that the handling
1413        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
1414        time (the PCRE_DOTALL option was changed this way some time ago: version
1415        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
1416        which was always a bit of a fudge. It also means that there is one less
1417        argument for the match() function, which reduces its stack requirements
1418        slightly. This change also fixes an incompatibility with Perl: the pattern
1419        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
1421    10. More internal refactoring has drastically reduced the number of recursive
1422        calls to match() for possessively repeated groups such as (abc)++ when
1423        using pcre_exec().
1425    11. While implementing 10, a number of bugs in the handling of groups were
1426        discovered and fixed:
1428        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
1429        (a|)*(?1) gave a compile-time internal error.
1430        ((a|)+)+  did not notice that the outer group could match an empty string.
1431        (^a|^)+   was not marked as anchored.
1432        (.*a|.*)+ was not marked as matching at start or after a newline.
1434    12. Yet more internal refactoring has removed another argument from the match()
1435        function. Special calls to this function are now indicated by setting a
1436        value in a variable in the "match data" data block.
1438    13. Be more explicit in pcre_study() instead of relying on "default" for
1439        opcodes that mean there is no starting character; this means that when new
1440        ones are added and accidentally left out of pcre_study(), testing should
1441        pick them up.
1443    14. The -s option of pcretest has been documented for ages as being an old
1444        synonym of -m (show memory usage). I have changed it to mean "force study
1445        for every regex", that is, assume /S for every regex. This is similar to -i
1446        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
1447        using it. It makes it easier to run collections of tests with and without
1448        study enabled, and thereby test pcre_study() more easily. All the standard
1449        tests are now run with and without -s (but some patterns can be marked as
1450        "never study" - see 20 below).
1452    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
1453        restoration of the capturing data to the outer values was not happening
1454        correctly.
1456    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
1457        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
1458        pattern had matched an empty string, and so incorrectly returned a no
1459        match.
1461    17. There was optimizing code for the last branch of non-capturing parentheses,
1462        and also for the obeyed branch of a conditional subexpression, which used
1463        tail recursion to cut down on stack usage. Unfortunately, now that there is
1464        the possibility of (*THEN) occurring in these branches, tail recursion is
1465        no longer possible because the return has to be checked for (*THEN). These
1466        two optimizations have therefore been removed. [But see 8.20/11 above.]
1468    18. If a pattern containing \R was studied, it was assumed that \R always
1469        matched two bytes, thus causing the minimum subject length to be
1470        incorrectly computed because \R can also match just one byte.
1472    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
1473        was incorrectly computed.
1475    20. If /S is present twice on a test pattern in pcretest input, it now
1476        *disables* studying, thereby overriding the use of -s on the command line
1477        (see 14 above). This is necessary for one or two tests to keep the output
1478        identical in both cases.
1480    21. When (*ACCEPT) was used in an assertion that matched an empty string and
1481        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
1483    22. When an atomic group that contained a capturing parenthesis was
1484        successfully matched, but the branch in which it appeared failed, the
1485        capturing was not being forgotten if a higher numbered group was later
1486        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
1487        group 1 to "a", when in fact it should be unset. This applied to multi-
1488        branched capturing and non-capturing groups, repeated or not, and also to
1489        positive assertions (capturing in negative assertions does not happen
1490        in PCRE) and also to nested atomic groups.
1492    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
1493        subject after a captured substring, to make it easier to tell which of a
1494        number of identical substrings has been captured.
1496    24. The way atomic groups are processed by pcre_exec() has been changed so that
1497        if they are repeated, backtracking one repetition now resets captured
1498        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
1499        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
1500        "aaa". Previously, it would have been "a". As part of this code
1501        refactoring, the way recursive calls are handled has also been changed.
1503    25. If an assertion condition captured any substrings, they were not passed
1504        back unless some other capturing happened later. For example, if
1505        (?(?=(a))a) was matched against "a", no capturing was returned.
1507    26. When studying a pattern that contained subroutine calls or assertions,
1508        the code for finding the minimum length of a possible match was handling
1509        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
1510        group 1 called group 2 while simultaneously a separate group 2 called group
1511        1). A stack overflow occurred in this case. I have fixed this by limiting
1512        the recursion depth to 10.
1514    27. Updated RunTest.bat in the distribution to the version supplied by Tom
1515        Fortmann. This supports explicit test numbers on the command line, and has
1516        argument validation and error reporting.
1518    28. An instance of \X with an unlimited repeat could fail if at any point the
1519        first character it looked at was a mark character.
1521    29. Some minor code refactoring concerning Unicode properties and scripts
1522        should reduce the stack requirement of match() slightly.
1524    30. Added the '=' option to pcretest to check the setting of unused capturing
1525        slots at the end of the pattern, which are documented as being -1, but are
1526        not included in the return count.
1528    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
1529        compiled something random. Now it gives a compile-time error (as does
1530        Perl).
1532    32. A *MARK encountered during the processing of a positive assertion is now
1533        recorded and passed back (compatible with Perl).
1535    33. If --only-matching or --colour was set on a pcregrep call whose pattern
1536        had alternative anchored branches, the search for a second match in a line
1537        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
1538        matched the line "0102" twice. The same bug affected patterns that started
1539        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
1540        twice.
1542    34. Previously, PCRE did not allow quantification of assertions. However, Perl
1543        does, and because of capturing effects, quantifying parenthesized
1544        assertions may at times be useful. Quantifiers are now allowed for
1545        parenthesized assertions.
1547    35. A minor code tidy in pcre_compile() when checking options for \R usage.
1549    36. \g was being checked for fancy things in a character class, when it should
1550        just be a literal "g".
1552    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
1553        appearance of a nested POSIX class supersedes an apparent external class.
1554        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
1555        unescaped square brackets may also appear as part of class names. For
1556        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
1557        more like Perl. (But see 8.20/1 above.)
1559    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
1560        was because it thought it was \N{name}, which is not supported).
1562    39. Add minix to OS list not supporting the -S option in pcretest.
1564    40. PCRE tries to detect cases of infinite recursion at compile time, but it
1565        cannot analyze patterns in sufficient detail to catch mutual recursions
1566        such as ((?1))((?2)). There is now a runtime test that gives an error if a
1567        subgroup is called recursively as a subpattern for a second time at the
1568        same position in the subject string. In previous releases this might have
1569        been caught by the recursion limit, or it might have run out of stack.
1571    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
1572        happen only once. PCRE was, however incorrectly giving a compile time error
1573        "recursive call could loop indefinitely" because it cannot analyze the
1574        pattern in sufficient detail. The compile time test no longer happens when
1575        PCRE is compiling a conditional subpattern, but actual runaway loops are
1576        now caught at runtime (see 40 above).
1578    42. It seems that Perl allows any characters other than a closing parenthesis
1579        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
1580        has been changed to be the same.
1582    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
1583        as not to get warnings when autogen.sh is called. Also changed
1584        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
1586    44. To help people who use pcregrep to scan files containing exceedingly long
1587        lines, the following changes have been made:
1589        (a) The default value of the buffer size parameter has been increased from
1590            8K to 20K. (The actual buffer used is three times this size.)
1592        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
1593            PCRE is built.
1595        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
1596            to be set at run time.
1598        (d) Numerical values in pcregrep options can be followed by K or M, for
1599            example --buffer-size=50K.
1601        (e) If a line being scanned overflows pcregrep's buffer, an error is now
1602            given and the return code is set to 2.
1604    45. Add a pointer to the latest mark to the callout data block.
1606    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
1607        partial match of an empty string instead of no match. This was specific to
1608        the use of ".".
1610    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
1611        complete match instead of a partial match. This bug was dependent on both
1612        the PCRE_UTF8 and PCRE_DOTALL options being set.
1614    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
1615        starting byte set, because \b was not being ignored.
1618    Version 8.12 15-Jan-2011
1619    ------------------------
1621    1.  Fixed some typos in the markup of the man pages, and wrote a script that
1622        checks for such things as part of the documentation building process.
1624    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
1625        --match-limit and --recursion-limit options (added for 8.11). In
1626        particular, this made one of the standard tests fail. (The integer value
1627        went into the wrong half of a long int.)
1629    3.  If the --colour option was given to pcregrep with -v (invert match), it
1630        did strange things, either producing crazy output, or crashing. It should,
1631        of course, ignore a request for colour when reporting lines that do not
1632        match.
1634    4.  Another pcregrep bug caused similar problems if --colour was specified with
1635        -M (multiline) and the pattern match finished with a line ending.
1637    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
1638        matched in multiline mode, the following line was shown as part of the
1639        match. This seems wrong, so I have changed it.
1641    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
1642        the check for further matches in the same line (so they could be coloured)
1643        to overrun the end of the current line. If another match was found, it was
1644        incorrectly shown (and then shown again when found in the next line).
1646    7.  If pcregrep was compiled under Windows, there was a reference to the
1647        function pcregrep_exit() before it was defined. I am assuming this was
1648        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
1649        reported by a user. I've moved the definition above the reference.
1652    Version 8.11 10-Dec-2010
1653    ------------------------
1655    1.  (*THEN) was not working properly if there were untried alternatives prior
1656        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
1657        backtracked to try for "b" instead of moving to the next alternative branch
1658        at the same level (in this case, to look for "c"). The Perl documentation
1659        is clear that when (*THEN) is backtracked onto, it goes to the "next
1660        alternative in the innermost enclosing group".
1662    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
1663        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
1664        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
1665        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
1666        (*THEN).
1668    3.  If \s appeared in a character class, it removed the VT character from
1669        the class, even if it had been included by some previous item, for example
1670        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
1671        of \s, but is part of the POSIX "space" class.)
1673    4.  A partial match never returns an empty string (because you can always
1674        match an empty string at the end of the subject); however the checking for
1675        an empty string was starting at the "start of match" point. This has been
1676        changed to the "earliest inspected character" point, because the returned
1677        data for a partial match starts at this character. This means that, for
1678        example, /(?<=abc)def/ gives a partial match for the subject "abc"
1679        (previously it gave "no match").
1681    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
1682        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
1683        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
1684        has an implication that the given string is incomplete (because a partial
1685        match is preferred over a full match). For this reason, these items now
1686        give a partial match in this situation. [Aside: previously, the one case
1687        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
1688        match rather than a full match, which was wrong by the old rules, but is
1689        now correct.]
1691    6.  There was a bug in the handling of #-introduced comments, recognized when
1692        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
1693        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
1694        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
1695        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
1696        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
1697        places in pcre_compile().
1699    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
1700        comments when looking ahead for named forward references to subpatterns,
1701        the only newline sequence it recognized was NL. It now handles newlines
1702        according to the set newline convention.
1704    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
1705        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
1706        cater for a lack of strerror(). These oversights have been fixed.
1708    9.  Added --match-limit and --recursion-limit to pcregrep.
1710    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
1712    11. When the -o option was used, pcregrep was setting a return code of 1, even
1713        when matches were found, and --line-buffered was not being honoured.
1715    12. Added an optional parentheses number to the -o and --only-matching options
1716        of pcregrep.
1718    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
1719        can match an empty string. The code to do it in pcretest and pcredemo
1720        needed fixing:
1722        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
1723            only one byte after an empty string match just before CRLF (this case
1724            just got forgotten; "any" and "anycrlf" were OK).
1726        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
1727            mode when an empty string match preceded an ASCII character followed by
1728            a non-ASCII character. (The code for advancing by one character rather
1729            than one byte was nonsense.)
1731        (c) The pcredemo.c sample program did not have any code at all to handle
1732            the cases when CRLF is a valid newline sequence.
1734    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
1735        as a starting offset was within the subject string. There is now a new
1736        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
1737        negative or greater than the length of the string. In order to test this,
1738        pcretest is extended to allow the setting of negative starting offsets.
1740    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
1741        starting offset points to the beginning of a UTF-8 character was
1742        unnecessarily clumsy. I tidied it up.
1744    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
1745        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
1747    17. Nobody had reported that the --include_dir option, which was added in
1748        release 7.7 should have been called --include-dir (hyphen, not underscore)
1749        for compatibility with GNU grep. I have changed it to --include-dir, but
1750        left --include_dir as an undocumented synonym, and the same for
1751        --exclude-dir, though that is not available in GNU grep, at least as of
1752        release 2.5.4.
1754    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
1755        characters from a string of bytes) have been redefined so as not to use
1756        loops, in order to improve performance in some environments. At the same
1757        time, I abstracted some of the common code into auxiliary macros to save
1758        repetition (this should not affect the compiled code).
1760    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
1761        compile-time error is now given if \c is not followed by an ASCII
1762        character, that is, a byte less than 128. (In EBCDIC mode, the code is
1763        different, and any byte value is allowed.)
1765    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
1766        START_OPTIMIZE option, which is now allowed at compile time - but just
1767        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
1768        to pcregrep and other applications that have no direct access to PCRE
1769        options. The new /Y option in pcretest sets this option when calling
1770        pcre_compile().
1772    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
1773        back references. Groups containing recursive back references were forced to
1774        be atomic by that change, but in the case of named groups, the amount of
1775        memory required was incorrectly computed, leading to "Failed: internal
1776        error: code overflow". This has been fixed.
1778    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
1779        pcretest.c, to avoid build problems in some Borland environments.
1782    Version 8.10 25-Jun-2010
1783    ------------------------
1785    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
1786        THEN.
1788    2.  (*ACCEPT) was not working when inside an atomic group.
1790    3.  Inside a character class, \B is treated as a literal by default, but
1791        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
1792        causes the error). The code is unchanged, but I tidied the documentation.
1794    4.  Inside a character class, PCRE always treated \R and \X as literals,
1795        whereas Perl faults them if its -w option is set. I have changed PCRE so
1796        that it faults them when PCRE_EXTRA is set.
1798    5.  Added support for \N, which always matches any character other than
1799        newline. (It is the same as "." when PCRE_DOTALL is not set.)
1801    6.  When compiling pcregrep with newer versions of gcc which may have
1802        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
1803        declared with attribute warn_unused_result" were given. Just casting the
1804        result to (void) does not stop the warnings; a more elaborate fudge is
1805        needed. I've used a macro to implement this.
1807    7.  Minor change to pcretest.c to avoid a compiler warning.
1809    8.  Added four artifical Unicode properties to help with an option to make
1810        \s etc use properties (see next item). The new properties are: Xan
1811        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
1813    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
1814        use Unicode properties. (*UCP) at the start of a pattern can be used to set
1815        this option. Modified pcretest to add /W to test this facility. Added
1816        REG_UCP to make it available via the POSIX interface.
1818    10. Added --line-buffered to pcregrep.
1820    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
1821        studied, and the match started with a letter with a code point greater than
1822        127 whose first byte was different to the first byte of the other case of
1823        the letter, the other case of this starting letter was not recognized
1824        (#976).
1826    12. If a pattern that was studied started with a repeated Unicode property
1827        test, for example, \p{Nd}+, there was the theoretical possibility of
1828        setting up an incorrect bitmap of starting bytes, but fortunately it could
1829        not have actually happened in practice until change 8 above was made (it
1830        added property types that matched character-matching opcodes).
1832    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
1833        possible starting bytes for non-anchored patterns.
1835    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
1836        \R, and also a number of cases that involve Unicode properties, both
1837        explicit and implicit when PCRE_UCP is set.
1839    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
1840        input, it could crash or give wrong results if characters with values
1841        greater than 0xc0 were present in the subject string. (Detail: it assumed
1842        UTF-8 input when processing these items.)
1844    16. Added a lot of (int) casts to avoid compiler warnings in systems where
1845        size_t is 64-bit (#991).
1847    17. Added a check for running out of memory when PCRE is compiled with
1848        --disable-stack-for-recursion (#990).
1850    18. If the last data line in a file for pcretest does not have a newline on
1851        the end, a newline was missing in the output.
1853    19. The default pcre_chartables.c file recognizes only ASCII characters (values
1854        less than 128) in its various bitmaps. However, there is a facility for
1855        generating tables according to the current locale when PCRE is compiled. It
1856        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
1857        characters, are recognized by isspace() and therefore were getting set in
1858        these tables, and indeed these tables seem to approximate to ISO 8859. This
1859        caused a problem in UTF-8 mode when pcre_study() was used to create a list
1860        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
1861        which of course cannot start UTF-8 characters. I have changed the code so
1862        that only real ASCII characters (less than 128) and the correct starting
1863        bytes for UTF-8 encodings are set for characters greater than 127 when in
1864        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
1865        altogether.)
1867    20. Added the /T option to pcretest so as to be able to run tests with non-
1868        standard character tables, thus making it possible to include the tests
1869        used for 19 above in the standard set of tests.
1871    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
1872        reference to a subpattern the other side of a comment that contains an
1873        opening parenthesis caused either an internal compiling error, or a
1874        reference to the wrong subpattern.
1877    Version 8.02 19-Mar-2010
1878    ------------------------
1880    1.  The Unicode data tables have been updated to Unicode 5.2.0.
1882    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
1883        configured.
1885    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
1886        original author of that file, following a query about its status.
1888    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
1889        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
1891    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
1892        quantifier applied to a forward-referencing subroutine call, could compile
1893        incorrect code or give the error "internal error: previously-checked
1894        referenced subpattern not found".
1896    6.  Both MS Visual Studio and Symbian OS have problems with initializing
1897        variables to point to external functions. For these systems, therefore,
1898        pcre_malloc etc. are now initialized to local functions that call the
1899        relevant global functions.
1901    7.  There were two entries missing in the vectors called coptable and poptable
1902        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
1903        I've fixed the data, and added a kludgy way of testing at compile time that
1904        the lengths are correct (equal to the number of opcodes).
1906    8.  Following on from 7, I added a similar kludge to check the length of the
1907        eint vector in pcreposix.c.
1909    9.  Error texts for pcre_compile() are held as one long string to avoid too
1910        much relocation at load time. To find a text, the string is searched,
1911        counting zeros. There was no check for running off the end of the string,
1912        which could happen if a new error number was added without updating the
1913        string.
1915    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
1917    11. \K was not working if it appeared in an atomic group or in a group that
1918        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
1919        \K is "not well defined" if used in an assertion. PCRE now accepts it if
1920        the assertion is positive, but not if it is negative.
1922    12. Change 11 fortuitously reduced the size of the stack frame used in the
1923        "match()" function of pcre_exec.c by one pointer. Forthcoming
1924        implementation of support for (*MARK) will need an extra pointer on the
1925        stack; I have reserved it now, so that the stack frame size does not
1926        decrease.
1928    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
1929        item in branch that calls a recursion is a subroutine call - as in the
1930        second branch in the above example - was incorrectly given the compile-
1931        time error "recursive call could loop indefinitely" because pcre_compile()
1932        was not correctly checking the subroutine for matching a non-empty string.
1934    14. The checks for overrunning compiling workspace could trigger after an
1935        overrun had occurred. This is a "should never occur" error, but it can be
1936        triggered by pathological patterns such as hundreds of nested parentheses.
1937        The checks now trigger 100 bytes before the end of the workspace.
1939    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
1942    Version 8.01 19-Jan-2010
1943    ------------------------
1945    1.  If a pattern contained a conditional subpattern with only one branch (in
1946        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
1947        computed the wrong minimum data length (which is of course zero for such
1948        subpatterns). This could cause incorrect "no match" results.
1950    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
1951        the pattern is reset in the first branch, pcre_compile() failed with
1952        "internal error: code overflow at offset...". This happened only when
1953        the reset was to the original external option setting. (An optimization
1954        abstracts leading options settings into an external setting, which was the
1955        cause of this.)
1957    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
1958        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
1959        assertion pattern did not match (meaning that the assertion was true), it
1960        was incorrectly treated as false if the SKIP had been reached during the
1961        matching. This also applied to assertions used as conditions.
1963    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
1964        assertion subpattern, including such a pattern used as a condition,
1965        unpredictable results occurred, instead of the error return
1968    5.  The C++ GlobalReplace function was not working like Perl for the special
1969        situation when an empty string is matched. It now does the fancy magic
1970        stuff that is necessary.
1972    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
1973        removed. (These were left over from very, very early versions of PCRE.)
1975    7.  Some cosmetic changes to the code to make life easier when compiling it
1976        as part of something else:
1978        (a) Change DEBUG to PCRE_DEBUG.
1980        (b) In pcre_compile(), rename the member of the "branch_chain" structure
1981            called "current" as "current_branch", to prevent a collision with the
1982            Linux macro when compiled as a kernel module.
1984        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
1985            prevent a collision with the Linux macro when compiled as a kernel
1986            module.
1988    8.  In pcre_compile() there are some checks for integer overflows that used to
1989        cast potentially large values to (double). This has been changed to that
1990        when building, a check for int64_t is made, and if it is found, it is used
1991        instead, thus avoiding the use of floating point arithmetic. (There is no
1992        other use of FP in PCRE.) If int64_t is not found, the fallback is to
1993        double.
1995    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
1996        2005 (difference between two addresses compared to an unsigned value).
1998    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
1999        custom one, because of the following reported problem in Windows:
2001          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
2002              under Win32.
2003          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
2004              therefore missing the function definition.
2005          - The compiler thus generates a "C" signature for the test function.
2006          - The linker fails to find the "C" function.
2007          - PCRE fails to configure if asked to do so against libbz2.
2009    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
2010        messages were output:
2012          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
2013          rerunning libtoolize, to keep the correct libtool macros in-tree.
2014          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
2016        I have done both of these things.
2018    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
2019        most of the time, it *can* run out if it is given a pattern that contains a
2020        runaway infinite recursion. I updated the discussion in the pcrestack man
2021        page.
2023    13. Now that we have gone to the x.xx style of version numbers, the minor
2024        version may start with zero. Using 08 or 09 is a bad idea because users
2025        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
2026        interpreted as invalid octal numbers. I've updated the previous comment in
2027        configure.ac, and also added a check that gives an error if 08 or 09 are
2028        used.
2030    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
2031        causing partial matching to fail when the end of the subject matched \W
2032        in a UTF-8 pattern where \W was quantified with a minimum of 3.
2034    15. There were some discrepancies between the declarations in pcre_internal.h
2035        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
2036        their definitions. The declarations used "const uschar *" and the
2037        definitions used USPTR. Even though USPTR is normally defined as "const
2038        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
2039        reported that: "This difference in casting confuses some C++ compilers, for
2040        example, SunCC recognizes above declarations as different functions and
2041        generates broken code for hbpcre." I have changed the declarations to use
2042        USPTR.
2044    16. GNU libtool is named differently on some systems. The autogen.sh script now
2045        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
2046        (FreeBSD).
2048    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
2049        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
2050        comment: "Figure out how to create a longlong from a string: strtoll and
2051        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
2052        instance, but it only takes 2 args instead of 3!"
2054    18. A subtle bug concerned with back references has been fixed by a change of
2055        specification, with a corresponding code fix. A pattern such as
2056        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
2057        refers, was giving matches when it shouldn't. For example, xa=xaaa would
2058        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
2059        same bug. Such groups have to be quantified to be useful, or contained
2060        inside another quantified group. (If there's no repetition, the reference
2061        can never match.) The problem arises because, having left the group and
2062        moved on to the rest of the pattern, a later failure that backtracks into
2063        the group uses the captured value from the final iteration of the group
2064        rather than the correct earlier one. I have fixed this in PCRE by forcing
2065        any group that contains a reference to itself to be an atomic group; that
2066        is, there cannot be any backtracking into it once it has completed. This is
2067        similar to recursive and subroutine calls.
2070    Version 8.00 19-Oct-09
2071    ----------------------
2073    1.  The table for translating pcre_compile() error codes into POSIX error codes
2074        was out-of-date, and there was no check on the pcre_compile() error code
2075        being within the table. This could lead to an OK return being given in
2076        error.
2078    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
2079        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
2080        in a Windows environment.
2082    3.  The pcregrep --count option prints the count for each file even when it is
2083        zero, as does GNU grep. However, pcregrep was also printing all files when
2084        --files-with-matches was added. Now, when both options are given, it prints
2085        counts only for those files that have at least one match. (GNU grep just
2086        prints the file name in this circumstance, but including the count seems
2087        more useful - otherwise, why use --count?) Also ensured that the
2088        combination -clh just lists non-zero counts, with no names.
2090    4.  The long form of the pcregrep -F option was incorrectly implemented as
2091        --fixed_strings instead of --fixed-strings. This is an incompatible change,
2092        but it seems right to fix it, and I didn't think it was worth preserving
2093        the old behaviour.
2095    5.  The command line items --regex=pattern and --regexp=pattern were not
2096        recognized by pcregrep, which required --regex pattern or --regexp pattern
2097        (with a space rather than an '='). The man page documented the '=' forms,
2098        which are compatible with GNU grep; these now work.
2100    6.  No libpcreposix.pc file was created for pkg-config; there was just
2101        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
2103    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
2104        when UCP support is not needed, by modifying the Python script that
2105        generates it from Unicode data files. This should not matter if the module
2106        is correctly used as a library, but I received one complaint about 50K of
2107        unwanted data. My guess is that the person linked everything into his
2108        program rather than using a library. Anyway, it does no harm.
2110    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
2111        was a minimum greater than 1 for a wide character in a possessive
2112        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
2113        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
2114        character. Chaos in the form of incorrect output or a compiling loop could
2115        result.
2117    9.  The restrictions on what a pattern can contain when partial matching is
2118        requested for pcre_exec() have been removed. All patterns can now be
2119        partially matched by this function. In addition, if there are at least two
2120        slots in the offset vector, the offset of the earliest inspected character
2121        for the match and the offset of the end of the subject are set in them when
2122        PCRE_ERROR_PARTIAL is returned.
2124    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
2125        synonymous with PCRE_PARTIAL, for backwards compatibility, and
2126        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
2127        and may be more useful for multi-segment matching.
2129    11. Partial matching with pcre_exec() is now more intuitive. A partial match
2130        used to be given if ever the end of the subject was reached; now it is
2131        given only if matching could not proceed because another character was
2132        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
2133        string "Z", which now yields "no match" instead of "partial match". In the
2134        case of pcre_dfa_exec(), "no match" is given if every matching path for the
2135        final character ended with (*FAIL).
2137    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
2138        if the pattern had a "must contain" character that was already found in the
2139        earlier partial match, unless partial matching was again requested. For
2140        example, with the pattern /dog.(body)?/, the "must contain" character is
2141        "g". If the first part-match was for the string "dog", restarting with
2142        "sbody" failed. This bug has been fixed.
2144    13. The string returned by pcre_dfa_exec() after a partial match has been
2145        changed so that it starts at the first inspected character rather than the
2146        first character of the match. This makes a difference only if the pattern
2147        starts with a lookbehind assertion or \b or \B (\K is not supported by
2148        pcre_dfa_exec()). It's an incompatible change, but it makes the two
2149        matching functions compatible, and I think it's the right thing to do.
2151    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
2152        so that the demonstration program is easily available in environments where
2153        PCRE has not been installed from source.
2155    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
2156        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
2157        library.
2159    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
2160        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
2161        is not the first non-POSIX option to be added. Clearly some people find
2162        these options useful.
2164    17. If a caller to the POSIX matching function regexec() passes a non-zero
2165        value for nmatch with a NULL value for pmatch, the value of
2166        nmatch is forced to zero.
2168    18. RunGrepTest did not have a test for the availability of the -u option of
2169        the diff command, as RunTest does. It now checks in the same way as
2170        RunTest, and also checks for the -b option.
2172    19. If an odd number of negated classes containing just a single character
2173        interposed, within parentheses, between a forward reference to a named
2174        subpattern and the definition of the subpattern, compilation crashed with
2175        an internal error, complaining that it could not find the referenced
2176        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
2177        [The bug was that it was starting one character too far in when skipping
2178        over the character class, thus treating the ] as data rather than
2179        terminating the class. This meant it could skip too much.]
2181    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
2182        /g option in pcretest when the pattern contains \K, which makes it possible
2183        to have an empty string match not at the start, even when the pattern is
2184        anchored. Updated pcretest and pcredemo to use this option.
2186    21. If the maximum number of capturing subpatterns in a recursion was greater
2187        than the maximum at the outer level, the higher number was returned, but
2188        with unset values at the outer level. The correct (outer level) value is
2189        now given.
2191    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
2192        PCRE did not set those parentheses (unlike Perl). I have now found a way to
2193        make it do so. The string so far is captured, making this feature
2194        compatible with Perl.
2196    23. The tests have been re-organized, adding tests 11 and 12, to make it
2197        possible to check the Perl 5.10 features against Perl 5.10.
2199    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
2200        pattern matches a fixed length string. PCRE did not allow this; now it
2201        does. Neither allows recursion.
2203    25. I finally figured out how to implement a request to provide the minimum
2204        length of subject string that was needed in order to match a given pattern.
2205        (It was back references and recursion that I had previously got hung up
2206        on.) This code has now been added to pcre_study(); it finds a lower bound
2207        to the length of subject needed. It is not necessarily the greatest lower
2208        bound, but using it to avoid searching strings that are too short does give
2209        some useful speed-ups. The value is available to calling programs via
2210        pcre_fullinfo().
2212    26. While implementing 25, I discovered to my embarrassment that pcretest had
2213        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
2214        study optimizations had never been tested with that matching function.
2215        Oops. What is worse, even when it was passed study data, there was a bug in
2216        pcre_dfa_exec() that meant it never actually used it. Double oops. There
2217        were also very few tests of studied patterns with pcre_dfa_exec().
2219    27. If (?| is used to create subpatterns with duplicate numbers, they are now
2220        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
2221        on the other side of the coin, they are no longer allowed to have different
2222        names, because these cannot be distinguished in PCRE, and this has caused
2223        confusion. (This is a difference from Perl.)
2225    28. When duplicate subpattern names are present (necessarily with different
2226        numbers, as required by 27 above), and a test is made by name in a
2227        conditional pattern, either for a subpattern having been matched, or for
2228        recursion in such a pattern, all the associated numbered subpatterns are
2229        tested, and the overall condition is true if the condition is true for any
2230        one of them. This is the way Perl works, and is also more like the way
2231        testing by number works.
2234    Version 7.9 11-Apr-09
2235    ---------------------
2237    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
2238        (pcretest), all targets were linked against these libraries. This included
2239        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
2240        libraries. This caused unwanted dependencies to be created. This problem
2241        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
2242        pcretest is linked with readline.
2244    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
2245        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
2246        moved outside it again, because FALSE and TRUE are already defined in AIX,
2247        but BOOL is not.
2249    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
2250        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
2252    4.  The pcregrep documentation said spaces were inserted as well as colons (or
2253        hyphens) following file names and line numbers when outputting matching
2254        lines. This is not true; no spaces are inserted. I have also clarified the
2255        wording for the --colour (or --color) option.
2257    5.  In pcregrep, when --colour was used with -o, the list of matching strings
2258        was not coloured; this is different to GNU grep, so I have changed it to be
2259        the same.
2261    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
2262        each matching line was coloured. Now it goes on to look for further matches
2263        of any of the test patterns, which is the same behaviour as GNU grep.
2265    7.  A pattern that could match an empty string could cause pcregrep to loop; it
2266        doesn't make sense to accept an empty string match in pcregrep, so I have
2267        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
2268        seems to be how GNU grep behaves. [But see later change 40 for release
2269        8.33.]
2271    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
2272        start or after a newline", because the conditional assertion was not being
2273        correctly handled. The rule now is that both the assertion and what follows
2274        in the first alternative must satisfy the test.
2276    9.  If auto-callout was enabled in a pattern with a conditional group whose
2277        condition was an assertion, PCRE could crash during matching, both with
2278        pcre_exec() and pcre_dfa_exec().
2280    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
2281        used for matching.
2283    11. Unicode property support in character classes was not working for
2284        characters (bytes) greater than 127 when not in UTF-8 mode.
2286    12. Added the -M command line option to pcretest.
2288    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
2290    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
2292    16. Added comments and documentation about mis-use of no_arg in the C++
2293        wrapper.
2295    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
2296        from Martin Jerabek that uses macro names for all relevant character and
2297        string constants.
2299    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
2300        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
2301        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
2302        these, but not everybody uses configure.
2304    19. A conditional group that had only one branch was not being correctly
2305        recognized as an item that could match an empty string. This meant that an
2306        enclosing group might also not be so recognized, causing infinite looping
2307        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
2308        with the subject "ab", where knowledge that the repeated group can match
2309        nothing is needed in order to break the loop.
2311    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
2312        exec(), but without supplying a callout function, matching went wrong.
2314    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
2315        leak if the size of the offset vector was greater than 30. When the vector
2316        is smaller, the saved offsets during recursion go onto a local stack
2317        vector, but for larger vectors malloc() is used. It was failing to free
2318        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
2319        error, in fact).
2321    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
2322        heapframe that is used only when UTF-8 support is enabled. This caused no
2323        problem, but was untidy.
2325    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
2326        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
2327        included within another project.
2329    24. Steven Van Ingelgem's patches to add more options to the CMake support,
2330        slightly modified by me:
2332          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
2333              not building pcregrep.
2335          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
2336              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
2338    25. Forward references, both numeric and by name, in patterns that made use of
2339        duplicate group numbers, could behave incorrectly or give incorrect errors,
2340        because when scanning forward to find the reference group, PCRE was not
2341        taking into account the duplicate group numbers. A pattern such as
2342        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
2344    26. Changed a few more instances of "const unsigned char *" to USPTR, making
2345        the feature of a custom pointer more persuasive (as requested by a user).
2347    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
2348        pcretest.c, inside #ifndefs, because it seems they are sometimes already
2349        pre-defined.
2351    28. Added support for (*UTF8) at the start of a pattern.
2353    29. Arrange for flags added by the "release type" setting in CMake to be shown
2354        in the configuration summary.
2357    Version 7.8 05-Sep-08
2358    ---------------------
2360    1.  Replaced UCP searching code with optimized version as implemented for Ad
2361        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
2362        stage table and inline lookup instead of a function, giving speed ups of 2
2363        to 5 times on some simple patterns that I tested. Permission was given to
2364        distribute the MultiStage2.py script that generates the tables (it's not in
2365        the tarball, but is in the Subversion repository).
2367    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
2368        scripts.
2370    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
2371        a group with a zero qualifier. The result of the study could be incorrect,
2372        or the function might crash, depending on the pattern.
2374    4.  Caseless matching was not working for non-ASCII characters in back
2375        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
2376        It now works when Unicode Property Support is available.
2378    5.  In pcretest, an escape such as \x{de} in the data was always generating
2379        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
2380        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
2381        truncation.
2383    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
2385    7.  Added two (int) casts to pcregrep when printing the difference of two
2386        pointers, in case they are 64-bit values.
2388    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
2389        test 2 if it fails.
2391    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
2392        and a #define of that name to empty if it is not externally set. This is to
2393        allow users of MSVC to set it if necessary.
2395    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
2396        the convenience functions in the pcre_get.c source file.
2398    11. An option change at the start of a pattern that had top-level alternatives
2399        could cause overwriting and/or a crash. This command provoked a crash in
2400        some environments:
2402          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
2404        This potential security problem was recorded as CVE-2008-2371.
2406    12. For a pattern where the match had to start at the beginning or immediately
2407        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
2408        pcre_dfa_exec() could read past the end of the passed subject if there was
2409        no match. To help with detecting such bugs (e.g. with valgrind), I modified
2410        pcretest so that it places the subject at the end of its malloc-ed buffer.
2412    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
2413        exec() might read past the end of the data buffer in UTF-8 mode.
2415    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
2416        the data contained the byte 0x85 as part of a UTF-8 character within its
2417        first line. This applied both to normal and DFA matching.
2419    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
2420        /^[^d]*?$/8 failed to match "abc".
2422    16. Added a missing copyright notice to pcrecpp_internal.h.
2424    17. Make it more clear in the documentation that values returned from
2425        pcre_exec() in ovector are byte offsets, not character counts.
2427    18. Tidied a few places to stop certain compilers from issuing warnings.
2429    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
2430        supplied by Stefan Weber. I made a further small update for 7.8 because
2431        there is a change of source arrangements: the pcre_searchfuncs.c module is
2432        replaced by pcre_ucd.c.
2435    Version 7.7 07-May-08
2436    ---------------------
2438    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
2439        a string to a long long, pretend we don't even have a long long." This is
2440        done by checking for the strtoq, strtoll, and _strtoi64 functions.
2442    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
2443        pre-7.6 versions, which defined a global no_arg variable instead of putting
2444        it in the RE class. (See also #8 below.)
2446    3.  Remove a line of dead code, identified by coverity and reported by Nuno
2447        Lopes.
2449    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
2451        (1) The include/exclude patterns were being applied to the whole pathnames
2452            of files, instead of just to the final components.
2454        (2) If there was more than one level of directory, the subdirectories were
2455            skipped unless they satisfied the include/exclude conditions. This is
2456            inconsistent with GNU grep (and could even be seen as contrary to the
2457            pcregrep specification - which I improved to make it absolutely clear).
2458            The action now is always to scan all levels of directory, and just
2459            apply the include/exclude patterns to regular files.
2461    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
2462        --exclude_dir in the tests to avoid scanning .svn directories.
2464    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
2465        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
2466        doesn't support NULs in patterns.
2468    7.  Added some missing "const"s to declarations of static tables in
2469        pcre_compile.c and pcre_dfa_exec.c.
2471    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
2472        caused by fix #2  above. (Subsequently also a second patch to fix the
2473        first patch. And a third patch - this was a messy problem.)
2475    9.  Applied Craig's patch to remove the use of push_back().
2477    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
2478        matching function regexec().
2480    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
2481        which, however, unlike Perl's \g{...}, are subroutine calls, not back
2482        references. PCRE supports relative numbers with this syntax (I don't think
2483        Oniguruma does).
2485    12. Previously, a group with a zero repeat such as (...){0} was completely
2486        omitted from the compiled regex. However, this means that if the group
2487        was called as a subroutine from elsewhere in the pattern, things went wrong
2488        (an internal error was given). Such groups are now left in the compiled
2489        pattern, with a new opcode that causes them to be skipped at execution
2490        time.
2492    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
2493        to the way PCRE behaves:
2495        (a) A lone ] character is dis-allowed (Perl treats it as data).
2497        (b) A back reference to an unmatched subpattern matches an empty string
2498            (Perl fails the current match path).
2500        (c) A data ] in a character class must be notated as \] because if the
2501            first data character in a class is ], it defines an empty class. (In
2502            Perl it is not possible to have an empty class.) The empty class []
2503            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
2504            The negative empty class [^] matches any one character, independently
2505            of the DOTALL setting.
2507    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
2508        non-existent subpattern following a character class starting with ']' and
2509        containing () gave an internal compiling error instead of "reference to
2510        non-existent subpattern". Fortunately, when the pattern did exist, the
2511        compiled code was correct. (When scanning forwards to check for the
2512        existence of the subpattern, it was treating the data ']' as terminating
2513        the class, so got the count wrong. When actually compiling, the reference
2514        was subsequently set up correctly.)
2516    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
2517        it was being rejected as not supported by pcre_dfa_exec(), even though
2518        other assertions are supported. I have made pcre_dfa_exec() support
2519        (*FAIL).
2521    16. The implementation of 13c above involved the invention of a new opcode,
2522        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
2523        cannot be changed at match time, I realized I could make a small
2524        improvement to matching performance by compiling OP_ALLANY instead of
2525        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
2526        on the OP_ANY path.
2528    17. Compiling pcretest on Windows with readline support failed without the
2529        following two fixes: (1) Make the unistd.h include conditional on
2530        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
2532    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
2533        ncurses library to be included for pcretest when ReadLine support is
2534        requested, but also to allow for it to be overridden. This patch came from
2535        Daniel Bergström.
2537    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
2538        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
2539        any errors with the current Unicode tables. Thanks to Peter Kankowski for
2540        spotting this.
2543    Version 7.6 28-Jan-08
2544    ---------------------
2546    1.  A character class containing a very large number of characters with
2547        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
2548        overflow.
2550    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
2551        HAVE_LONG_LONG is not defined.
2553    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
2554        bring them up to date and include new features. This patch includes:
2556        - Fixed PH's badly added libz and libbz2 support.
2557        - Fixed a problem with static linking.
2558        - Added pcredemo. [But later removed - see 7 below.]
2559        - Fixed dftables problem and added an option.
2560        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
2561            HAVE_LONG_LONG.
2562        - Added readline support for pcretest.
2563        - Added an listing of the option settings after cmake has run.
2565    4.  A user submitted a patch to Makefile that makes it easy to create
2566        "pcre.dll" under mingw when using Configure/Make. I added stuff to
2567        Makefile.am that cause it to include this special target, without
2568        affecting anything else. Note that the same mingw target plus all
2569        the other distribution libraries and programs are now supported
2570        when configuring with CMake (see 6 below) instead of with
2571        Configure/Make.
2573    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
2574        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
2575        exported in the Windows port". It has not yet been confirmed that the patch
2576        solves the problem, but it does no harm.
2578    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
2579        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
2580        with CMake, and also correct the comment about stack recursion.
2582    7.  Remove the automatic building of pcredemo from the ./configure system and
2583        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
2584        of a program that users should build themselves after PCRE is installed, so
2585        building it automatically is not really right. What is more, it gave
2586        trouble in some build environments.
2588    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
2591    Version 7.5 10-Jan-08
2592    ---------------------
2594    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
2595        values in parens when parsing an RE using the C++ wrapper."
2597    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
2598        Characters greater than 255 were excluded from the class instead of being
2599        included.
2601    3.  The same bug as (2) above applied to negated POSIX classes such as
2602        [:^space:].
2604    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
2605        defined or documented. It seems to have been a typo for PCRE_STATIC, so
2606        I have changed it.
2608    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
2609        first named subpattern) and a construct such as (?&a) would reference the
2610        first named subpattern whose name started with "a" (in other words, the
2611        length check was missing). Both these problems are fixed. "Subpattern name
2612        expected" is now given for (?&) (a zero-length name), and this patch also
2613        makes it give the same error for \k'' (previously it complained that that
2614        was a reference to a non-existent subpattern).
2616    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
2617        this is right because (?- can be followed by option settings as well as by
2618        digits. I have, however, made the messages clearer.
2620    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
2621        than the number used in the conditional) now cause a compile-time error.
2622        This is actually not compatible with Perl, which accepts such patterns, but
2623        treats the conditional as always being FALSE (as PCRE used to), but it
2624        seems to me that giving a diagnostic is better.
2626    8.  Change "alphameric" to the more common word "alphanumeric" in comments
2627        and messages.
2629    9.  Fix two occurrences of "backslash" in comments that should have been
2630        "backspace".
2632    10. Remove two redundant lines of code that can never be obeyed (their function
2633        was moved elsewhere).
2635    11. The program that makes PCRE's Unicode character property table had a bug
2636        which caused it to generate incorrect table entries for sequences of
2637        characters that have the same character type, but are in different scripts.
2638        It amalgamated them into a single range, with the script of the first of
2639        them. In other words, some characters were in the wrong script. There were
2640        thirteen such cases, affecting characters in the following ranges:
2642          U+002b0 - U+002c1
2643          U+0060c - U+0060d
2644          U+0061e - U+00612
2645          U+0064b - U+0065e
2646          U+0074d - U+0076d
2647          U+01800 - U+01805
2648          U+01d00 - U+01d77
2649          U+01d9b - U+01dbf
2650          U+0200b - U+0200f
2651          U+030fc - U+030fe
2652          U+03260 - U+0327f
2653          U+0fb46 - U+0fbb1
2654          U+10450 - U+1049d
2656    12. The -o option (show only the matching part of a line) for pcregrep was not
2657        compatible with GNU grep in that, if there was more than one match in a
2658        line, it showed only the first of them. It now behaves in the same way as
2659        GNU grep.
2661    13. If the -o and -v options were combined for pcregrep, it printed a blank
2662        line for every non-matching line. GNU grep prints nothing, and pcregrep now
2663        does the same. The return code can be used to tell if there were any
2664        non-matching lines.
2666    14. Added --file-offsets and --line-offsets to pcregrep.
2668    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
2669        infinitely looping recursion. The bug was that positive lookaheads were not
2670        being skipped when checking for a possible empty match (negative lookaheads
2671        and both kinds of lookbehind were skipped).
2673    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
2674        inclusion of <windows.h> to before rather than after the definition of
2675        INVALID_FILE_ATTRIBUTES (patch from David Byron).
2677    17. Specifying a possessive quantifier with a specific limit for a Unicode
2678        character property caused pcre_compile() to compile bad code, which led at
2679        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
2680        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
2681        caused the error; without that there was no problem.
2683    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
2685    19. Added --enable-pcretest-libreadline.
2687    20. In pcrecpp.cc, the variable 'count' was incremented twice in
2688        RE::GlobalReplace(). As a result, the number of replacements returned was
2689        double what it should be. I removed one of the increments, but Craig sent a
2690        later patch that removed the other one (the right fix) and added unit tests
2691        that check the return values (which was not done before).
2693    21. Several CMake things:
2695        (1) Arranged that, when cmake is used on Unix, the libraries end up with
2696            the names libpcre and libpcreposix, not just pcre and pcreposix.
2698        (2) The above change means that pcretest and pcregrep are now correctly
2699            linked with the newly-built libraries, not previously installed ones.
2703    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
2704        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
2705        UTF-8 newline character). The key issue is that the pattern starts .*;
2706        this means that the match must be either at the beginning, or after a
2707        newline. The bug was in the code for advancing after a failed match and
2708        checking that the new position followed a newline. It was not taking
2709        account of UTF-8 characters correctly.
2711    23. PCRE was behaving differently from Perl in the way it recognized POSIX
2712        character classes. PCRE was not treating the sequence [:...:] as a
2713        character class unless the ... were all letters. Perl, however, seems to
2714        allow any characters between [: and :], though of course it rejects as
2715        unknown any "names" that contain non-letters, because all the known class
2716        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
2717        for example, whereas PCRE did not - it did not recognize a POSIX character
2718        class. This seemed a bit dangerous, so the code has been changed to be
2719        closer to Perl. The behaviour is not identical to Perl, because PCRE will
2720        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
2721        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
2722        Perl does, and where it didn't before.
2724    24. Rewrite so as to remove the single use of %n from pcregrep because in some
2725        Windows environments %n is disabled by default.
2728    Version 7.4 21-Sep-07
2729    ---------------------
2731    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
2732        means that a class such as [\s] counted as "explicit reference to CR or
2733        LF". That isn't really right - the whole point of the change was to try to
2734        help when there was an actual mention of one of the two characters. So now
2735        the change happens only if \r or \n (or a literal CR or LF) character is
2736        encountered.
2738    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
2739        of both had grown to the point where there were only 3 bits left.
2740        Fortunately, there was spare space in the data structure, and so I have
2741        moved the internal flags into a new 16-bit field to free up more option
2742        bits.
2744    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
2745        but did not set the internal JCHANGED flag - either of these is enough to
2746        control the way the "get" function works - but the PCRE_INFO_JCHANGED
2747        facility is supposed to tell if (?J) was ever used, so now (?J) at the
2748        start sets both bits.
2750    4.  Added options (at build time, compile time, exec time) to change \R from
2751        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
2753    5.  doc/pcresyntax.html was missing from the distribution.
2755    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
2756        compatibility, even though it is no longer used.
2758    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
2759        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
2760        windows.h file is present (where different names are used). [This was
2761        reversed later after testing - see 16 below.]
2763    8.  Changed all #include <config.h> to #include "config.h". There were also
2764        some further <pcre.h> cases that I changed to "pcre.h".
2766    9.  When pcregrep was used with the --colour option, it missed the line ending
2767        sequence off the lines that it output.
2769    10. It was pointed out to me that arrays of string pointers cause lots of
2770        relocations when a shared library is dynamically loaded. A technique of
2771        using a single long string with a table of offsets can drastically reduce
2772        these. I have refactored PCRE in four places to do this. The result is
2773        dramatic:
2775          Originally:                          290
2776          After changing UCP table:            187
2777          After changing error message table:   43
2778          After changing table of "verbs"       36
2779          After changing table of Posix names   22
2781        Thanks to the folks working on Gregex for glib for this insight.
2783    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
2784        unicode-properties was also set.
2786    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
2788    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
2789        checked only for CRLF.
2791    14. Added casts to pcretest.c to avoid compiler warnings.
2793    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
2795    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
2796        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
2797        entirely. This removes changes made in 7 above.
2799    17. The CMake files have been updated, and there is now more information about
2800        building with CMake in the NON-UNIX-USE document.
2803    Version 7.3 28-Aug-07
2804    ---------------------
2806     1. In the rejigging of the build system that eventually resulted in 7.1, the
2807        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
2808        brackets there is not right, since it causes compilers to look for an
2809        installed pcre.h, not the version that is in the source that is being
2810        compiled (which of course may be different). I have changed it back to:
2812          #include "pcre.h"
2814        I have a vague recollection that the change was concerned with compiling in
2815        different directories, but in the new build system, that is taken care of
2816        by the VPATH setting the Makefile.
2818     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
2819        when the subject happened to end in the byte 0x85 (e.g. if the last
2820        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
2821        characters but of course it shouldn't be taken as a newline when it is part
2822        of another character. The bug was that, for an unlimited repeat of . in
2823        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
2824        characters when looking for a newline.
2826     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
2828     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
2829        in debug output.
2831     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
2832        long printing in the pcrecpp unittest when running under MinGW.
2834     6. ESC_K was left out of the EBCDIC table.
2836     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
2837        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
2838        limit also applies to "virtual nesting" when a pattern is recursive, and in
2839        this case 1000 isn't so big. I have been able to remove this limit at the
2840        expense of backing off one optimization in certain circumstances. Normally,
2841        when pcre_exec() would call its internal match() function recursively and
2842        immediately return the result unconditionally, it uses a "tail recursion"
2843        feature to save stack. However, when a subpattern that can match an empty
2844        string has an unlimited repetition quantifier, it no longer makes this
2845        optimization. That gives it a stack frame in which to save the data for
2846        checking that an empty string has been matched. Previously this was taken
2847        from the 1000-entry workspace that had been reserved. So now there is no
2848        explicit limit, but more stack is used.
2850     8. Applied Daniel's patches to solve problems with the import/export magic
2851        syntax that is required for Windows, and which was going wrong for the
2852        pcreposix and pcrecpp parts of the library. These were overlooked when this
2853        problem was solved for the main library.
2855     9. There were some crude static tests to avoid integer overflow when computing
2856        the size of patterns that contain repeated groups with explicit upper
2857        limits. As the maximum quantifier is 65535, the maximum group length was
2858        set at 30,000 so that the product of these two numbers did not overflow a
2859        32-bit integer. However, it turns out that people want to use groups that
2860        are longer than 30,000 bytes (though not repeat them that many times).
2861        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
2862        made it possible to implement the integer overflow checks in a much more
2863        dynamic way, which I have now done. The artificial limitation on group
2864        length has been removed - we now have only the limit on the total length of
2865        the compiled pattern, which depends on the LINK_SIZE setting.
2867    10. Fixed a bug in the documentation for get/copy named substring when
2868        duplicate names are permitted. If none of the named substrings are set, the
2869        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
2870        empty string.
2872    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
2873        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
2874        because the ] is interpreted as the first data character and the
2875        terminating ] is not found. PCRE has been made compatible with Perl in this
2876        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
2877        cause memory overwriting.
2879    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
2880        string has been matched (to stop an infinite loop). It was not recognizing
2881        a conditional subpattern that could match an empty string if that
2882        subpattern was within another subpattern. For example, it looped when
2883        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
2884        condition was not nested. This bug has been fixed.
2886    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
2887        past the start of the subject in the presence of bytes with the top bit
2888        set, for example "\x8aBCD".
2890    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
2891        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
2893    14. Optimized (?!) to (*FAIL).
2895    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
2896        This restricts code points to be within the range 0 to 0x10FFFF, excluding
2897        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
2898        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
2899        does: it's just the validity check that is more restrictive.
2901    16. Inserted checks for integer overflows during escape sequence (backslash)
2902        processing, and also fixed erroneous offset values for syntax errors during
2903        backslash processing.
2905    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
2906        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
2908    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
2909        caused an overrun.
2911    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
2912        something other than just ASCII characters) inside a group that had an
2913        unlimited repeat caused a loop at compile time (while checking to see
2914        whether the group could match an empty string).
2916    20. Debugging a pattern containing \p or \P could cause a crash. For example,
2917        [\P{Any}] did so. (Error in the code for printing property names.)
2919    21. An orphan \E inside a character class could cause a crash.
2921    22. A repeated capturing bracket such as (A)? could cause a wild memory
2922        reference during compilation.
2924    23. There are several functions in pcre_compile() that scan along a compiled
2925        expression for various reasons (e.g. to see if it's fixed length for look
2926        behind). There were bugs in these functions when a repeated \p or \P was
2927        present in the pattern. These operators have additional parameters compared
2928        with \d, etc, and these were not being taken into account when moving along
2929        the compiled data. Specifically:
2931        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
2932            length.
2934        (b) An item such as \pL+ within a repeated group could cause crashes or
2935            loops.
2937        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
2938            "reference to non-existent subpattern" error.
2940        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
2942    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
2943        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
2945    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
2947    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
2948        character were causing crashes (broken optimization).
2950    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
2951        \p or \P) caused a compile-time loop.
2953    28. More problems have arisen in unanchored patterns when CRLF is a valid line
2954        break. For example, the unstudied pattern [\r\n]A does not match the string
2955        "\r\nA" because change 7.0/46 below moves the current point on by two
2956        characters after failing to match at the start. However, the pattern \nA
2957        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
2958        the same is true. There doesn't seem any very clean way out of this, but
2959        what I have chosen to do makes the common cases work: PCRE now takes note
2960        of whether there can be an explicit match for \r or \n anywhere in the
2961        pattern, and if so, 7.0/46 no longer applies. As part of this change,
2962        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
2963        pattern has explicit CR or LF references.
2965    29. Added (*CR) etc for changing newline setting at start of pattern.
2968    Version 7.2 19-Jun-07
2969    ---------------------
2971     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
2972        which is apparently normally available under Windows.
2974     2. Re-jig the pcregrep tests with different newline settings in an attempt
2975        to make them independent of the local environment's newline setting.
2977     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
2979     4. Some of the "internals" tests were previously cut out when the link size
2980        was not 2, because the output contained actual offsets. The recent new
2981        "Z" feature of pcretest means that these can be cut out, making the tests
2982        usable with all link sizes.
2984     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
2985        stack recursion. This gives a massive performance boost under BSD, but just
2986        a small improvement under Linux. However, it saves one field in the frame
2987        in all cases.
2989     6. Added more features from the forthcoming Perl 5.10:
2991        (a) (?-n) (where n is a string of digits) is a relative subroutine or
2992            recursion call. It refers to the nth most recently opened parentheses.
2994        (b) (?+n) is also a relative subroutine call; it refers to the nth next
2995            to be opened parentheses.
2997        (c) Conditions that refer to capturing parentheses can be specified
2998            relatively, for example, (?(-2)... or (?(+3)...
3000        (d) \K resets the start of the current match so that everything before
3001            is not part of it.
3003        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
3005        (f) \g{name} is another synonym - part of Perl 5.10's unification of
3006            reference syntax.
3008        (g) (?| introduces a group in which the numbering of parentheses in each
3009            alternative starts with the same number.
3011        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
3013     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
3016     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
3017        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
3018        for detecting groups that can match an empty string.
3020     9. A pattern with a very large number of alternatives (more than several
3021        hundred) was running out of internal workspace during the pre-compile
3022        phase, where pcre_compile() figures out how much memory will be needed. A
3023        bit of new cunning has reduced the workspace needed for groups with
3024        alternatives. The 1000-alternative test pattern now uses 12 bytes of
3025        workspace instead of running out of the 4096 that are available.
3027    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
3029    11. Applied patch from Google to remove an optimization that didn't quite work.
3030        The report of the bug said:
3032          pcrecpp::RE("a*").FullMatch("aaa") matches, while
3033          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
3034          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
3036    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
3037        it matched the wrong number of bytes.
3040    Version 7.1 24-Apr-07
3041    ---------------------
3043     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
3044        that is more "standard", making use of automake and other Autotools. There
3045        is some re-arrangement of the files and adjustment of comments consequent
3046        on this.
3048     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
3049        for recursive directory scanning broke on some systems because the files
3050        are not scanned in any specific order and on different systems the order
3051        was different. A call to "sort" has been inserted into RunGrepTest for the
3052        approprate test as a short-term fix. In the longer term there may be an
3053        alternative.
3055     3. I had an email from Eric Raymond about problems translating some of PCRE's
3056        man pages to HTML (despite the fact that I distribute HTML pages, some
3057        people do their own conversions for various reasons). The problems
3058        concerned the use of low-level troff macros .br and .in. I have therefore
3059        removed all such uses from the man pages (some were redundant, some could
3060        be replaced by .nf/.fi pairs). The 132html script that I use to generate
3061        HTML has been updated to handle .nf/.fi and to complain if it encounters
3062        .br or .in.
3064     4. Updated comments in configure.ac that get placed in config.h.in and also
3065        arranged for config.h to be included in the distribution, with the name
3066        config.h.generic, for the benefit of those who have to compile without
3067        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
3069     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
3070        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
3071        makevp.bat for the current PCRE, using the additional files
3072        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
3074     6. A Windows user reported a minor discrepancy with test 2, which turned out
3075        to be caused by a trailing space on an input line that had got lost in his
3076        copy. The trailing space was an accident, so I've just removed it.
3078     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
3079        that is needed.
3081     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
3082        as "const" (a) because they are and (b) because it helps the PHP
3083        maintainers who have recently made a script to detect big data structures
3084        in the php code that should be moved to the .rodata section. I remembered
3085        to update Builducptable as well, so it won't revert if ucptable.h is ever
3086        re-created.
3088     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
3089        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
3090        order to be able to cut out the UTF-8 tables in the latter when UTF-8
3091        support is not required. This saves 1.5-2K of code, which is important in
3092        some applications.
3094        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
3095        so as not to refer to the tables, even though these functions will never be
3096        called when UTF-8 support is disabled. Otherwise there are problems with a
3097        shared library.
3099    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
3101        (a) It was defining its arguments as char * instead of void *.
3103        (b) It was assuming that all moves were upwards in memory; this was true
3104            a long time ago when I wrote it, but is no longer the case.
3106        The emulated memove() is provided for those environments that have neither
3107        memmove() nor bcopy(). I didn't think anyone used it these days, but that
3108        is clearly not the case, as these two bugs were recently reported.
3110    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
3111        and Detrail to create the HTML documentation, the .txt form of the man
3112        pages, and it removes trailing spaces from listed files. It also creates
3113        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
3114        case, it wraps all the #defines with #ifndefs. This script should be run
3115        before "make dist".
3117    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
3118        with Unicode property support.
3120        (a) For a maximizing quantifier, if the two different cases of the
3121            character were of different lengths in their UTF-8 codings (there are
3122            some cases like this - I found 11), and the matching function had to
3123            back up over a mixture of the two cases, it incorrectly assumed they
3124            were both the same length.
3126        (b) When PCRE was configured to use the heap rather than the stack for
3127            recursion during matching, it was not correctly preserving the data for
3128            the other case of a UTF-8 character when checking ahead for a match
3129            while processing a minimizing repeat. If the check also involved
3130            matching a wide character, but failed, corruption could cause an
3131            erroneous result when trying to check for a repeat of the original
3132            character.
3134    13. Some tidying changes to the testing mechanism:
3136        (a) The RunTest script now detects the internal link size and whether there
3137            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
3138            values substituted by "configure". (The RunGrepTest script already did
3139            this for UTF-8.) The configure.ac script no longer substitutes the
3140            relevant variables.
3142        (b) The debugging options /B and /D in pcretest show the compiled bytecode
3143            with length and offset values. This means that the output is different
3144            for different internal link sizes. Test 2 is skipped for link sizes
3145            other than 2 because of this, bypassing the problem. Unfortunately,
3146            there was also a test in test 3 (the locale tests) that used /B and
3147            failed for link sizes other than 2. Rather than cut the whole test out,
3148            I have added a new /Z option to pcretest that replaces the length and
3149            offset values with spaces. This is now used to make test 3 independent
3150            of link size. (Test 2 will be tidied up later.)
3152    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
3153        segmentation fault instead of returning the appropriate error message.
3155    15. In multiline mode when the newline sequence was set to "any", the pattern
3156        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
3157        This doesn't seem right; it now treats the CRLF combination as the line
3158        ending, and so does not match in that case. It's only a pattern such as ^$
3159        that would hit this one: something like ^ABC$ would have failed after \r
3160        and then tried again after \r\n.
3162    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
3163        in an attempt to make files that differ only in their line terminators
3164        compare equal. This works on Linux.
3166    17. Under certain error circumstances pcregrep might try to free random memory
3167        as it exited. This is now fixed, thanks to valgrind.
3169    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
3170        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
3171        was because its rules for how to advance for /g after matching an empty
3172        string at the end of a line did not allow for this case. They now check for
3173        it specially.
3175    20. pcretest is supposed to handle patterns and data of any length, by
3176        extending its buffers when necessary. It was getting this wrong when the
3177        buffer for a data line had to be extended.
3179    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
3180        CRLF as a newline sequence.
3182    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
3183        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
3184        I have nevertheless tidied it up.
3186    23. Added some casts to kill warnings from HP-UX ia64 compiler.
3188    24. Added a man page for pcre-config.
3191    Version 7.0 19-Dec-06
3192    ---------------------
3194     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
3195        moving to gcc 4.1.1.
3197     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
3198        sys/time.h, which is documented as needed for this function. It doesn't
3199        seem to matter on Linux, but it showed up on some releases of OS X.
3201     3. It seems that there are systems where bytes whose values are greater than
3202        127 match isprint() in the "C" locale. The "C" locale should be the
3203        default when a C program starts up. In most systems, only ASCII printing
3204        characters match isprint(). This difference caused the output from pcretest
3205        to vary, making some of the tests fail. I have changed pcretest so that:
3207        (a) When it is outputting text in the compiled version of a pattern, bytes
3208            other than 32-126 are always shown as hex escapes.
3210        (b) When it is outputting text that is a matched part of a subject string,
3211            it does the same, unless a different locale has been set for the match
3212            (using the /L modifier). In this case, it uses isprint() to decide.
3214     4. Fixed a major bug that caused incorrect computation of the amount of memory
3215        required for a compiled pattern when options that changed within the
3216        pattern affected the logic of the preliminary scan that determines the
3217        length. The relevant options are -x, and -i in UTF-8 mode. The result was
3218        that the computed length was too small. The symptoms of this bug were
3219        either the PCRE error "internal error: code overflow" from pcre_compile(),
3220        or a glibc crash with a message such as "pcretest: free(): invalid next
3221        size (fast)". Examples of patterns that provoked this bug (shown in
3222        pcretest format) are:
3224          /(?-x: )/x
3225          /(?x)(?-x: \s*#\s*)/
3226          /((?i)[\x{c0}])/8
3227          /(?i:[\x{c0}])/8
3229        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
3230        is now done differently.
3232     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
3233        wrapper classes; (b) implement a new function in the C++ scanner that is
3234        more efficient than the old way of doing things because it avoids levels of
3235        recursion in the regex matching; (c) add a paragraph to the documentation
3236        for the FullMatch() function.
3238     6. The escape sequence \n was being treated as whatever was defined as
3239        "newline". Not only was this contrary to the documentation, which states
3240        that \n is character 10 (hex 0A), but it also went horribly wrong when
3241        "newline" was defined as CRLF. This has been fixed.
3243     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
3244        was being set to -1 for the "end of line" case (supposedly a value that no
3245        character can have). Though this value is never used (the check for end of
3246        line is "zero bytes in current character"), it caused compiler complaints.
3247        I've changed it to 0xffffffff.
3249     8. In pcre_version.c, the version string was being built by a sequence of
3250        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
3251        string (as it is for production releases) called a macro with an empty
3252        argument. The C standard says the result of this is undefined. The gcc
3253        compiler treats it as an empty string (which was what was wanted) but it is
3254        reported that Visual C gives an error. The source has been hacked around to
3255        avoid this problem.
3257     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
3258        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
3259        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
3260        of them did).
3262    10. Originally, pcretest opened its input and output without "b"; then I was
3263        told that "b" was needed in some environments, so it was added for release
3264        5.0 to both the input and output. (It makes no difference on Unix-like
3265        systems.) Later I was told that it is wrong for the input on Windows. I've
3266        now abstracted the modes into two macros, to make it easier to fiddle with
3267        them, and removed "b" from the input mode under Windows.
3269    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
3271    12. Added -help and --help to pcretest as an official way of being reminded
3272        of the options.
3274    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
3275        and pcrecpp.cc because they annoy compilers at high warning levels.
3277    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
3279    15. Fixed an occurrence of == in configure.ac that should have been = (shell
3280        scripts are not C programs :-) and which was not noticed because it works
3281        on Linux.
3283    16. pcretest is supposed to handle any length of pattern and data line (as one
3284        line or as a continued sequence of lines) by extending its input buffer if
3285        necessary. This feature was broken for very long pattern lines, leading to
3286        a string of junk being passed to pcre_compile() if the pattern was longer
3287        than about 50K.
3289    17. I have done a major re-factoring of the way pcre_compile() computes the
3290        amount of memory needed for a compiled pattern. Previously, there was code
3291        that made a preliminary scan of the pattern in order to do this. That was
3292        OK when PCRE was new, but as the facilities have expanded, it has become
3293        harder and harder to keep it in step with the real compile phase, and there
3294        have been a number of bugs (see for example, 4 above). I have now found a
3295        cunning way of running the real compile function in a "fake" mode that
3296        enables it to compute how much memory it would need, while actually only
3297        ever using a few hundred bytes of working memory and without too many
3298        tests of the mode. This should make future maintenance and development
3299        easier. A side effect of this work is that the limit of 200 on the nesting
3300        depth of parentheses has been removed (though this was never a serious
3301        limitation, I suspect). However, there is a downside: pcre_compile() now
3302        runs more slowly than before (30% or more, depending on the pattern). I
3303        hope this isn't a big issue. There is no effect on runtime performance.
3305    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
3306        newline (only possible for the last line of a file) and it was a
3307        pattern that set a locale (followed by /Lsomething), pcretest crashed.
3309    19. Added additional timing features to pcretest. (1) The -tm option now times
3310        matching only, not compiling. (2) Both -t and -tm can be followed, as a
3311        separate command line item, by a number that specifies the number of
3312        repeats to use when timing. The default is 50000; this gives better
3313        precision, but takes uncomfortably long for very large patterns.
3315    20. Extended pcre_study() to be more clever in cases where a branch of a
3316        subpattern has no definite first character. For example, (a*|b*)[cd] would
3317        previously give no result from pcre_study(). Now it recognizes that the
3318        first character must be a, b, c, or d.
3320    21. There was an incorrect error "recursive call could loop indefinitely" if
3321        a subpattern (or the entire pattern) that was being tested for matching an
3322        empty string contained only one non-empty item after a nested subpattern.
3323        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
3324        incorrectly, because the \d was being skipped in the check.
3326    22. The pcretest program now has a new pattern option /B and a command line
3327        option -b, which is equivalent to adding /B to every pattern. This causes
3328        it to show the compiled bytecode, without the additional information that
3329        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
3330        is the same as /B/I).
3332    23. A new optimization is now able automatically to treat some sequences such
3333        as a*b as a*+b. More specifically, if something simple (such as a character
3334        or a simple class like \d) has an unlimited quantifier, and is followed by
3335        something that cannot possibly match the quantified thing, the quantifier
3336        is automatically "possessified".
3338    24. A recursive reference to a subpattern whose number was greater than 39
3339        went wrong under certain circumstances in UTF-8 mode. This bug could also
3340        have affected the operation of pcre_study().
3342    25. Realized that a little bit of performance could be had by replacing
3343        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
3345    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
3347    27. Possessive quantifiers such as a++ were previously implemented by turning
3348        them into atomic groups such as ($>a+). Now they have their own opcodes,
3349        which improves performance. This includes the automatically created ones
3350        from 23 above.
3352    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
3353        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
3354        the first matched character to be a colon. This applied both to named and
3355        numbered groups.
3357    29. The ucpinternal.h header file was missing its idempotency #ifdef.
3359    30. I was sent a "project" file called libpcre.a.dev which I understand makes
3360        building PCRE on Windows easier, so I have included it in the distribution.
3362    31. There is now a check in pcretest against a ridiculously large number being
3363        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
3364        loop, the loop is abandoned.
3366    32. Forward references to subpatterns in conditions such as (?(2)...) where
3367        subpattern 2 is defined later cause pcre_compile() to search forwards in
3368        the pattern for the relevant set of parentheses. This search went wrong
3369        when there were unescaped parentheses in a character class, parentheses
3370        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
3372    33. "Subroutine" calls and backreferences were previously restricted to
3373        referencing subpatterns earlier in the regex. This restriction has now
3374        been removed.
3376    34. Added a number of extra features that are going to be in Perl 5.10. On the
3377        whole, these are just syntactic alternatives for features that PCRE had
3378        previously implemented using the Python syntax or my own invention. The
3379        other formats are all retained for compatibility.
3381        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
3382            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
3383            also .NET compatible.
3385        (b) A recursion or subroutine call to a named group can now be defined as
3386            (?&name) as well as (?P>name).
3388        (c) A backreference to a named group can now be defined as \k<name> or
3389            \k'name' as well as (?P=name). The new forms, as well as being in Perl
3390            5.10, are also .NET compatible.
3392        (d) A conditional reference to a named group can now use the syntax
3393            (?(<name>) or (?('name') as well as (?(name).
3395        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
3396            groups (named and numbered) that are never evaluated inline, but can be
3397            called as "subroutines" from elsewhere. In effect, the DEFINE condition
3398            is always false. There may be only one alternative in such a group.
3400        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
3401            as the simple (?(R). The condition is true only if the most recent
3402            recursion is that of the given number or name. It does not search out
3403            through the entire recursion stack.
3405        (g) The escape \gN or \g{N} has been added, where N is a positive or
3406            negative number, specifying an absolute or relative reference.
3408    35. Tidied to get rid of some further signed/unsigned compiler warnings and
3409        some "unreachable code" warnings.
3411    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
3412        things, this adds five new scripts.
3414    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
3415        There were also incompatibilities regarding the handling of \Q..\E inside
3416        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
3417        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
3419    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
3420        matches an empty string, and forcibly breaks the loop. There were bugs in
3421        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
3422        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
3423        separate and independent bugs (that affected different cases) have been
3424        fixed.
3426    39. Refactored the code to abolish the use of different opcodes for small
3427        capturing bracket numbers. This is a tidy that I avoided doing when I
3428        removed the limit on the number of capturing brackets for 3.5 back in 2001.
3429        The new approach is not only tidier, it makes it possible to reduce the
3430        memory needed to fix the previous bug (38).
3432    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
3433        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
3434        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
3435        mode.
3437    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
3438        report.
3440    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
3441        copy construction and assignment in the C++ wrapper.
3443    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
3444        couple of bugs that could have given wrong results in the "--newline=crlf"
3445        case.
3447    44. Added a number of casts and did some reorganization of signed/unsigned int
3448        variables following suggestions from Dair Grant. Also renamed the variable
3449        "this" as "item" because it is a C++ keyword.
3451    45. Arranged for dftables to add
3453          #include "pcre_internal.h"
3455        to pcre_chartables.c because without it, gcc 4.x may remove the array
3456        definition from the final binary if PCRE is built into a static library and
3457        dead code stripping is activated.
3459    46. For an unanchored pattern, if a match attempt fails at the start of a
3460        newline sequence, and the newline setting is CRLF or ANY, and the next two
3461        characters are CRLF, advance by two characters instead of one.
3464    Version 6.7 04-Jul-06
3465    ---------------------
3467     1. In order to handle tests when input lines are enormously long, pcretest has
3468        been re-factored so that it automatically extends its buffers when
3469        necessary. The code is crude, but this _is_ just a test program. The
3470        default size has been increased from 32K to 50K.
3472     2. The code in pcre_study() was using the value of the re argument before
3473        testing it for NULL. (Of course, in any sensible call of the function, it
3474        won't be NULL.)
3476     3. The memmove() emulation function in pcre_internal.h, which is used on
3477        systems that lack both memmove() and bcopy() - that is, hardly ever -
3478        was missing a "static" storage class specifier.
3480     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
3481        containing an extended class (one that cannot be represented by a bitmap
3482        because it contains high-valued characters or Unicode property items, e.g.
3483        [\pZ]). Almost always one would set UTF-8 mode when processing such a
3484        pattern, but PCRE should not loop if you do not (it no longer does).
3485        [Detail: two cases were found: (a) a repeated subpattern containing an
3486        extended class; (b) a recursive reference to a subpattern that followed a
3487        previous extended class. It wasn't skipping over the extended class
3488        correctly when UTF-8 mode was not set.]
3490     5. A negated single-character class was not being recognized as fixed-length
3491        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
3492        compile error "lookbehind assertion is not fixed length".
3494     6. The RunPerlTest auxiliary script was showing an unexpected difference
3495        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
3496        write a Perl script that can interpret lines of an input file either as
3497        byte characters or as UTF-8, which is what "perltest" was being required to
3498        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
3499        can't do is switch easily at run time between having the "use utf8;" pragma
3500        or not. In the end, I fudged it by using the RunPerlTest script to insert
3501        "use utf8;" explicitly for the UTF-8 tests.
3503     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
3504        the end of the subject string, contrary to the documentation and to what
3505        Perl does. This was true of both matching functions. Now it matches only at
3506        the start of the subject and immediately after *internal* newlines.
3508     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
3509        a pointer to an int instead of a pointer to an unsigned long int. This
3510        caused problems on 64-bit systems.
3512     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
3513        instance of the 'standard' template library not being so standard".
3515    10. There was no check on the number of named subpatterns nor the maximum
3516        length of a subpattern name. The product of these values is used to compute
3517        the size of the memory block for a compiled pattern. By supplying a very
3518        long subpattern name and a large number of named subpatterns, the size
3519        computation could be caused to overflow. This is now prevented by limiting
3520        the length of names to 32 characters, and the number of named subpatterns
3521        to 10,000.
3523    11. Subpatterns that are repeated with specific counts have to be replicated in
3524        the compiled pattern. The size of memory for this was computed from the
3525        length of the subpattern and the repeat count. The latter is limited to
3526        65535, but there was no limit on the former, meaning that integer overflow
3527        could in principle occur. The compiled length of a repeated subpattern is
3528        now limited to 30,000 bytes in order to prevent this.
3530    12. Added the optional facility to have named substrings with the same name.
3532    13. Added the ability to use a named substring as a condition, using the
3533        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
3534        are numbers (not recommended). Forward references are permitted.
3536    14. Added forward references in named backreferences (if you see what I mean).
3538    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
3539        pattern could run off the end of the subject. For example, the pattern
3540        "(?s)(.{1,5})"8 did this with the subject "ab".
3542    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
3543        PCRE_CASELESS was set when matching characters that were quantified with ?
3544        or *.
3546    17. A character class other than a single negated character that had a minimum
3547        but no maximum quantifier - for example [ab]{6,} - was not handled
3548        correctly by pce_dfa_exec(). It would match only one character.
3550    18. A valid (though odd) pattern that looked like a POSIX character
3551        class but used an invalid character after [ (for example [[,abc,]]) caused
3552        pcre_compile() to give the error "Failed: internal error: code overflow" or
3553        in some cases to crash with a glibc free() error. This could even happen if
3554        the pattern terminated after [[ but there just happened to be a sequence of
3555        letters, a binary zero, and a closing ] in the memory that followed.
3557    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
3558        over the years. Originally (before any Unicode support), just the bottom 8
3559        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
3560        output from "man perlunicode" includes this:
3562          The regular expression compiler produces polymorphic opcodes.  That
3563          is, the pattern adapts to the data and automatically switches to
3564          the Unicode character scheme when presented with Unicode data--or
3565          instead uses a traditional byte scheme when presented with byte
3566          data.
3568        Sadly, a wide octal escape does not cause a switch, and in a string with
3569        no other multibyte characters, these octal escapes are treated as before.
3570        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
3571        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
3572        Unicode string.
3574        I have not perpetrated such confusion in PCRE. Up till now, it took just
3575        the bottom 8 bits, as in old Perl. I have now made octal escapes with
3576        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
3577        translate to the appropriate multibyte character.
3579    29. Applied some refactoring to reduce the number of warnings from Microsoft
3580        and Borland compilers. This has included removing the fudge introduced