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revision 19 by nigel, Sat Feb 24 21:38:33 2007 UTC revision 551 by ph10, Sun Oct 10 17:33:07 2010 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 8.11 10-Oct-2010
5    ------------------------
6    
7    1.  (*THEN) was not working properly if there were untried alternatives prior
8        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
9        backtracked to try for "b" instead of moving to the next alternative branch
10        at the same level (in this case, to look for "c"). The Perl documentation
11        is clear that when (*THEN) is backtracked onto, it goes to the "next
12        alternative in the innermost enclosing group".
13    
14    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
15        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
16        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
17        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
18        (*THEN).
19    
20    
21    Version 8.10 25-Jun-2010
22    ------------------------
23    
24    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
25        THEN.
26    
27    2.  (*ACCEPT) was not working when inside an atomic group.
28    
29    3.  Inside a character class, \B is treated as a literal by default, but
30        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
31        causes the error). The code is unchanged, but I tidied the documentation.
32    
33    4.  Inside a character class, PCRE always treated \R and \X as literals,
34        whereas Perl faults them if its -w option is set. I have changed PCRE so
35        that it faults them when PCRE_EXTRA is set.
36    
37    5.  Added support for \N, which always matches any character other than
38        newline. (It is the same as "." when PCRE_DOTALL is not set.)
39    
40    6.  When compiling pcregrep with newer versions of gcc which may have
41        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
42        declared with attribute warn_unused_result" were given. Just casting the
43        result to (void) does not stop the warnings; a more elaborate fudge is
44        needed. I've used a macro to implement this.
45    
46    7.  Minor change to pcretest.c to avoid a compiler warning.
47    
48    8.  Added four artifical Unicode properties to help with an option to make
49        \s etc use properties (see next item). The new properties are: Xan
50        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
51    
52    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
53        use Unicode properties. (*UCP) at the start of a pattern can be used to set
54        this option. Modified pcretest to add /W to test this facility. Added
55        REG_UCP to make it available via the POSIX interface.
56    
57    10. Added --line-buffered to pcregrep.
58    
59    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
60        studied, and the match started with a letter with a code point greater than
61        127 whose first byte was different to the first byte of the other case of
62        the letter, the other case of this starting letter was not recognized
63        (#976).
64    
65    12. If a pattern that was studied started with a repeated Unicode property
66        test, for example, \p{Nd}+, there was the theoretical possibility of
67        setting up an incorrect bitmap of starting bytes, but fortunately it could
68        not have actually happened in practice until change 8 above was made (it
69        added property types that matched character-matching opcodes).
70    
71    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
72        possible starting bytes for non-anchored patterns.
73    
74    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
75        \R, and also a number of cases that involve Unicode properties, both
76        explicit and implicit when PCRE_UCP is set.
77    
78    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
79        input, it could crash or give wrong results if characters with values
80        greater than 0xc0 were present in the subject string. (Detail: it assumed
81        UTF-8 input when processing these items.)
82    
83    16. Added a lot of (int) casts to avoid compiler warnings in systems where
84        size_t is 64-bit (#991).
85    
86    17. Added a check for running out of memory when PCRE is compiled with
87        --disable-stack-for-recursion (#990).
88    
89    18. If the last data line in a file for pcretest does not have a newline on
90        the end, a newline was missing in the output.
91    
92    19. The default pcre_chartables.c file recognizes only ASCII characters (values
93        less than 128) in its various bitmaps. However, there is a facility for
94        generating tables according to the current locale when PCRE is compiled. It
95        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
96        characters, are recognized by isspace() and therefore were getting set in
97        these tables, and indeed these tables seem to approximate to ISO 8859. This
98        caused a problem in UTF-8 mode when pcre_study() was used to create a list
99        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
100        which of course cannot start UTF-8 characters. I have changed the code so
101        that only real ASCII characters (less than 128) and the correct starting
102        bytes for UTF-8 encodings are set for characters greater than 127 when in
103        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
104        altogether.)
105    
106    20. Added the /T option to pcretest so as to be able to run tests with non-
107        standard character tables, thus making it possible to include the tests
108        used for 19 above in the standard set of tests.
109    
110    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
111        reference to a subpattern the other side of a comment that contains an
112        opening parenthesis caused either an internal compiling error, or a
113        reference to the wrong subpattern.
114    
115    
116    Version 8.02 19-Mar-2010
117    ------------------------
118    
119    1.  The Unicode data tables have been updated to Unicode 5.2.0.
120    
121    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
122        configured.
123    
124    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
125        original author of that file, following a query about its status.
126    
127    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
128        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
129    
130    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
131        quantifier applied to a forward-referencing subroutine call, could compile
132        incorrect code or give the error "internal error: previously-checked
133        referenced subpattern not found".
134    
135    6.  Both MS Visual Studio and Symbian OS have problems with initializing
136        variables to point to external functions. For these systems, therefore,
137        pcre_malloc etc. are now initialized to local functions that call the
138        relevant global functions.
139    
140    7.  There were two entries missing in the vectors called coptable and poptable
141        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
142        I've fixed the data, and added a kludgy way of testing at compile time that
143        the lengths are correct (equal to the number of opcodes).
144    
145    8.  Following on from 7, I added a similar kludge to check the length of the
146        eint vector in pcreposix.c.
147    
148    9.  Error texts for pcre_compile() are held as one long string to avoid too
149        much relocation at load time. To find a text, the string is searched,
150        counting zeros. There was no check for running off the end of the string,
151        which could happen if a new error number was added without updating the
152        string.
153    
154    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
155    
156    11. \K was not working if it appeared in an atomic group or in a group that
157        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
158        \K is "not well defined" if used in an assertion. PCRE now accepts it if
159        the assertion is positive, but not if it is negative.
160    
161    12. Change 11 fortuitously reduced the size of the stack frame used in the
162        "match()" function of pcre_exec.c by one pointer. Forthcoming
163        implementation of support for (*MARK) will need an extra pointer on the
164        stack; I have reserved it now, so that the stack frame size does not
165        decrease.
166    
167    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
168        item in branch that calls a recursion is a subroutine call - as in the
169        second branch in the above example - was incorrectly given the compile-
170        time error "recursive call could loop indefinitely" because pcre_compile()
171        was not correctly checking the subroutine for matching a non-empty string.
172    
173    14. The checks for overrunning compiling workspace could trigger after an
174        overrun had occurred. This is a "should never occur" error, but it can be
175        triggered by pathological patterns such as hundreds of nested parentheses.
176        The checks now trigger 100 bytes before the end of the workspace.
177    
178    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
179    
180    
181    Version 8.01 19-Jan-2010
182    ------------------------
183    
184    1.  If a pattern contained a conditional subpattern with only one branch (in
185        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
186        computed the wrong minimum data length (which is of course zero for such
187        subpatterns). This could cause incorrect "no match" results.
188    
189    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
190        the pattern is reset in the first branch, pcre_compile() failed with
191        "internal error: code overflow at offset...". This happened only when
192        the reset was to the original external option setting. (An optimization
193        abstracts leading options settings into an external setting, which was the
194        cause of this.)
195    
196    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
197        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
198        assertion pattern did not match (meaning that the assertion was true), it
199        was incorrectly treated as false if the SKIP had been reached during the
200        matching. This also applied to assertions used as conditions.
201    
202    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
203        assertion subpattern, including such a pattern used as a condition,
204        unpredictable results occurred, instead of the error return
205        PCRE_ERROR_DFA_UITEM.
206    
207    5.  The C++ GlobalReplace function was not working like Perl for the special
208        situation when an empty string is matched. It now does the fancy magic
209        stuff that is necessary.
210    
211    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
212        removed. (These were left over from very, very early versions of PCRE.)
213    
214    7.  Some cosmetic changes to the code to make life easier when compiling it
215        as part of something else:
216    
217        (a) Change DEBUG to PCRE_DEBUG.
218    
219        (b) In pcre_compile(), rename the member of the "branch_chain" structure
220            called "current" as "current_branch", to prevent a collision with the
221            Linux macro when compiled as a kernel module.
222    
223        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
224            prevent a collision with the Linux macro when compiled as a kernel
225            module.
226    
227    8.  In pcre_compile() there are some checks for integer overflows that used to
228        cast potentially large values to (double). This has been changed to that
229        when building, a check for int64_t is made, and if it is found, it is used
230        instead, thus avoiding the use of floating point arithmetic. (There is no
231        other use of FP in PCRE.) If int64_t is not found, the fallback is to
232        double.
233    
234    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
235        2005 (difference between two addresses compared to an unsigned value).
236    
237    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
238        custom one, because of the following reported problem in Windows:
239    
240          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
241              under Win32.
242          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
243              therefore missing the function definition.
244          - The compiler thus generates a "C" signature for the test function.
245          - The linker fails to find the "C" function.
246          - PCRE fails to configure if asked to do so against libbz2.
247    
248    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
249        messages were output:
250    
251          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
252          rerunning libtoolize, to keep the correct libtool macros in-tree.
253          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
254    
255        I have done both of these things.
256    
257    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
258        most of the time, it *can* run out if it is given a pattern that contains a
259        runaway infinite recursion. I updated the discussion in the pcrestack man
260        page.
261    
262    13. Now that we have gone to the x.xx style of version numbers, the minor
263        version may start with zero. Using 08 or 09 is a bad idea because users
264        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
265        interpreted as invalid octal numbers. I've updated the previous comment in
266        configure.ac, and also added a check that gives an error if 08 or 09 are
267        used.
268    
269    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
270        causing partial matching to fail when the end of the subject matched \W
271        in a UTF-8 pattern where \W was quantified with a minimum of 3.
272    
273    15. There were some discrepancies between the declarations in pcre_internal.h
274        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
275        their definitions. The declarations used "const uschar *" and the
276        definitions used USPTR. Even though USPTR is normally defined as "const
277        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
278        reported that: "This difference in casting confuses some C++ compilers, for
279        example, SunCC recognizes above declarations as different functions and
280        generates broken code for hbpcre." I have changed the declarations to use
281        USPTR.
282    
283    16. GNU libtool is named differently on some systems. The autogen.sh script now
284        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
285        (FreeBSD).
286    
287    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
288        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
289        comment: "Figure out how to create a longlong from a string: strtoll and
290        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
291        instance, but it only takes 2 args instead of 3!"
292    
293    18. A subtle bug concerned with back references has been fixed by a change of
294        specification, with a corresponding code fix. A pattern such as
295        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
296        refers, was giving matches when it shouldn't. For example, xa=xaaa would
297        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
298        same bug. Such groups have to be quantified to be useful, or contained
299        inside another quantified group. (If there's no repetition, the reference
300        can never match.) The problem arises because, having left the group and
301        moved on to the rest of the pattern, a later failure that backtracks into
302        the group uses the captured value from the final iteration of the group
303        rather than the correct earlier one. I have fixed this in PCRE by forcing
304        any group that contains a reference to itself to be an atomic group; that
305        is, there cannot be any backtracking into it once it has completed. This is
306        similar to recursive and subroutine calls.
307    
308    
309    Version 8.00 19-Oct-09
310    ----------------------
311    
312    1.  The table for translating pcre_compile() error codes into POSIX error codes
313        was out-of-date, and there was no check on the pcre_compile() error code
314        being within the table. This could lead to an OK return being given in
315        error.
316    
317    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
318        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
319        in a Windows environment.
320    
321    3.  The pcregrep --count option prints the count for each file even when it is
322        zero, as does GNU grep. However, pcregrep was also printing all files when
323        --files-with-matches was added. Now, when both options are given, it prints
324        counts only for those files that have at least one match. (GNU grep just
325        prints the file name in this circumstance, but including the count seems
326        more useful - otherwise, why use --count?) Also ensured that the
327        combination -clh just lists non-zero counts, with no names.
328    
329    4.  The long form of the pcregrep -F option was incorrectly implemented as
330        --fixed_strings instead of --fixed-strings. This is an incompatible change,
331        but it seems right to fix it, and I didn't think it was worth preserving
332        the old behaviour.
333    
334    5.  The command line items --regex=pattern and --regexp=pattern were not
335        recognized by pcregrep, which required --regex pattern or --regexp pattern
336        (with a space rather than an '='). The man page documented the '=' forms,
337        which are compatible with GNU grep; these now work.
338    
339    6.  No libpcreposix.pc file was created for pkg-config; there was just
340        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
341    
342    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
343        when UCP support is not needed, by modifying the Python script that
344        generates it from Unicode data files. This should not matter if the module
345        is correctly used as a library, but I received one complaint about 50K of
346        unwanted data. My guess is that the person linked everything into his
347        program rather than using a library. Anyway, it does no harm.
348    
349    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
350        was a minimum greater than 1 for a wide character in a possessive
351        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
352        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
353        character. Chaos in the form of incorrect output or a compiling loop could
354        result.
355    
356    9.  The restrictions on what a pattern can contain when partial matching is
357        requested for pcre_exec() have been removed. All patterns can now be
358        partially matched by this function. In addition, if there are at least two
359        slots in the offset vector, the offset of the earliest inspected character
360        for the match and the offset of the end of the subject are set in them when
361        PCRE_ERROR_PARTIAL is returned.
362    
363    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
364        synonymous with PCRE_PARTIAL, for backwards compatibility, and
365        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
366        and may be more useful for multi-segment matching.
367    
368    11. Partial matching with pcre_exec() is now more intuitive. A partial match
369        used to be given if ever the end of the subject was reached; now it is
370        given only if matching could not proceed because another character was
371        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
372        string "Z", which now yields "no match" instead of "partial match". In the
373        case of pcre_dfa_exec(), "no match" is given if every matching path for the
374        final character ended with (*FAIL).
375    
376    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
377        if the pattern had a "must contain" character that was already found in the
378        earlier partial match, unless partial matching was again requested. For
379        example, with the pattern /dog.(body)?/, the "must contain" character is
380        "g". If the first part-match was for the string "dog", restarting with
381        "sbody" failed. This bug has been fixed.
382    
383    13. The string returned by pcre_dfa_exec() after a partial match has been
384        changed so that it starts at the first inspected character rather than the
385        first character of the match. This makes a difference only if the pattern
386        starts with a lookbehind assertion or \b or \B (\K is not supported by
387        pcre_dfa_exec()). It's an incompatible change, but it makes the two
388        matching functions compatible, and I think it's the right thing to do.
389    
390    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
391        so that the demonstration program is easily available in environments where
392        PCRE has not been installed from source.
393    
394    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
395        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
396        library.
397    
398    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
399        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
400        is not the first non-POSIX option to be added. Clearly some people find
401        these options useful.
402    
403    17. If a caller to the POSIX matching function regexec() passes a non-zero
404        value for nmatch with a NULL value for pmatch, the value of
405        nmatch is forced to zero.
406    
407    18. RunGrepTest did not have a test for the availability of the -u option of
408        the diff command, as RunTest does. It now checks in the same way as
409        RunTest, and also checks for the -b option.
410    
411    19. If an odd number of negated classes containing just a single character
412        interposed, within parentheses, between a forward reference to a named
413        subpattern and the definition of the subpattern, compilation crashed with
414        an internal error, complaining that it could not find the referenced
415        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
416        [The bug was that it was starting one character too far in when skipping
417        over the character class, thus treating the ] as data rather than
418        terminating the class. This meant it could skip too much.]
419    
420    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
421        /g option in pcretest when the pattern contains \K, which makes it possible
422        to have an empty string match not at the start, even when the pattern is
423        anchored. Updated pcretest and pcredemo to use this option.
424    
425    21. If the maximum number of capturing subpatterns in a recursion was greater
426        than the maximum at the outer level, the higher number was returned, but
427        with unset values at the outer level. The correct (outer level) value is
428        now given.
429    
430    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
431        PCRE did not set those parentheses (unlike Perl). I have now found a way to
432        make it do so. The string so far is captured, making this feature
433        compatible with Perl.
434    
435    23. The tests have been re-organized, adding tests 11 and 12, to make it
436        possible to check the Perl 5.10 features against Perl 5.10.
437    
438    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
439        pattern matches a fixed length string. PCRE did not allow this; now it
440        does. Neither allows recursion.
441    
442    25. I finally figured out how to implement a request to provide the minimum
443        length of subject string that was needed in order to match a given pattern.
444        (It was back references and recursion that I had previously got hung up
445        on.) This code has now been added to pcre_study(); it finds a lower bound
446        to the length of subject needed. It is not necessarily the greatest lower
447        bound, but using it to avoid searching strings that are too short does give
448        some useful speed-ups. The value is available to calling programs via
449        pcre_fullinfo().
450    
451    26. While implementing 25, I discovered to my embarrassment that pcretest had
452        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
453        study optimizations had never been tested with that matching function.
454        Oops. What is worse, even when it was passed study data, there was a bug in
455        pcre_dfa_exec() that meant it never actually used it. Double oops. There
456        were also very few tests of studied patterns with pcre_dfa_exec().
457    
458    27. If (?| is used to create subpatterns with duplicate numbers, they are now
459        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
460        on the other side of the coin, they are no longer allowed to have different
461        names, because these cannot be distinguished in PCRE, and this has caused
462        confusion. (This is a difference from Perl.)
463    
464    28. When duplicate subpattern names are present (necessarily with different
465        numbers, as required by 27 above), and a test is made by name in a
466        conditional pattern, either for a subpattern having been matched, or for
467        recursion in such a pattern, all the associated numbered subpatterns are
468        tested, and the overall condition is true if the condition is true for any
469        one of them. This is the way Perl works, and is also more like the way
470        testing by number works.
471    
472    
473    Version 7.9 11-Apr-09
474    ---------------------
475    
476    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
477        (pcretest), all targets were linked against these libraries. This included
478        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
479        libraries. This caused unwanted dependencies to be created. This problem
480        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
481        pcretest is linked with readline.
482    
483    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
484        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
485        moved outside it again, because FALSE and TRUE are already defined in AIX,
486        but BOOL is not.
487    
488    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
489        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
490    
491    4.  The pcregrep documentation said spaces were inserted as well as colons (or
492        hyphens) following file names and line numbers when outputting matching
493        lines. This is not true; no spaces are inserted. I have also clarified the
494        wording for the --colour (or --color) option.
495    
496    5.  In pcregrep, when --colour was used with -o, the list of matching strings
497        was not coloured; this is different to GNU grep, so I have changed it to be
498        the same.
499    
500    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
501        each matching line was coloured. Now it goes on to look for further matches
502        of any of the test patterns, which is the same behaviour as GNU grep.
503    
504    7.  A pattern that could match an empty string could cause pcregrep to loop; it
505        doesn't make sense to accept an empty string match in pcregrep, so I have
506        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
507        seems to be how GNU grep behaves.
508    
509    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
510        start or after a newline", because the conditional assertion was not being
511        correctly handled. The rule now is that both the assertion and what follows
512        in the first alternative must satisfy the test.
513    
514    9.  If auto-callout was enabled in a pattern with a conditional group whose
515        condition was an assertion, PCRE could crash during matching, both with
516        pcre_exec() and pcre_dfa_exec().
517    
518    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
519        used for matching.
520    
521    11. Unicode property support in character classes was not working for
522        characters (bytes) greater than 127 when not in UTF-8 mode.
523    
524    12. Added the -M command line option to pcretest.
525    
526    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
527    
528    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
529    
530    16. Added comments and documentation about mis-use of no_arg in the C++
531        wrapper.
532    
533    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
534        from Martin Jerabek that uses macro names for all relevant character and
535        string constants.
536    
537    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
538        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
539        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
540        these, but not everybody uses configure.
541    
542    19. A conditional group that had only one branch was not being correctly
543        recognized as an item that could match an empty string. This meant that an
544        enclosing group might also not be so recognized, causing infinite looping
545        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
546        with the subject "ab", where knowledge that the repeated group can match
547        nothing is needed in order to break the loop.
548    
549    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
550        exec(), but without supplying a callout function, matching went wrong.
551    
552    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
553        leak if the size of the offset vector was greater than 30. When the vector
554        is smaller, the saved offsets during recursion go onto a local stack
555        vector, but for larger vectors malloc() is used. It was failing to free
556        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
557        error, in fact).
558    
559    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
560        heapframe that is used only when UTF-8 support is enabled. This caused no
561        problem, but was untidy.
562    
563    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
564        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
565        included within another project.
566    
567    24. Steven Van Ingelgem's patches to add more options to the CMake support,
568        slightly modified by me:
569    
570          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
571              not building pcregrep.
572    
573          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
574              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
575    
576    25. Forward references, both numeric and by name, in patterns that made use of
577        duplicate group numbers, could behave incorrectly or give incorrect errors,
578        because when scanning forward to find the reference group, PCRE was not
579        taking into account the duplicate group numbers. A pattern such as
580        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
581    
582    26. Changed a few more instances of "const unsigned char *" to USPTR, making
583        the feature of a custom pointer more persuasive (as requested by a user).
584    
585    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
586        pcretest.c, inside #ifndefs, because it seems they are sometimes already
587        pre-defined.
588    
589    28. Added support for (*UTF8) at the start of a pattern.
590    
591    29. Arrange for flags added by the "release type" setting in CMake to be shown
592        in the configuration summary.
593    
594    
595    Version 7.8 05-Sep-08
596    ---------------------
597    
598    1.  Replaced UCP searching code with optimized version as implemented for Ad
599        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
600        stage table and inline lookup instead of a function, giving speed ups of 2
601        to 5 times on some simple patterns that I tested. Permission was given to
602        distribute the MultiStage2.py script that generates the tables (it's not in
603        the tarball, but is in the Subversion repository).
604    
605    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
606        scripts.
607    
608    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
609        a group with a zero qualifier. The result of the study could be incorrect,
610        or the function might crash, depending on the pattern.
611    
612    4.  Caseless matching was not working for non-ASCII characters in back
613        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
614        It now works when Unicode Property Support is available.
615    
616    5.  In pcretest, an escape such as \x{de} in the data was always generating
617        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
618        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
619        truncation.
620    
621    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
622    
623    7.  Added two (int) casts to pcregrep when printing the difference of two
624        pointers, in case they are 64-bit values.
625    
626    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
627        test 2 if it fails.
628    
629    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
630        and a #define of that name to empty if it is not externally set. This is to
631        allow users of MSVC to set it if necessary.
632    
633    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
634        the convenience functions in the pcre_get.c source file.
635    
636    11. An option change at the start of a pattern that had top-level alternatives
637        could cause overwriting and/or a crash. This command provoked a crash in
638        some environments:
639    
640          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
641    
642        This potential security problem was recorded as CVE-2008-2371.
643    
644    12. For a pattern where the match had to start at the beginning or immediately
645        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
646        pcre_dfa_exec() could read past the end of the passed subject if there was
647        no match. To help with detecting such bugs (e.g. with valgrind), I modified
648        pcretest so that it places the subject at the end of its malloc-ed buffer.
649    
650    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
651        exec() might read past the end of the data buffer in UTF-8 mode.
652    
653    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
654        the data contained the byte 0x85 as part of a UTF-8 character within its
655        first line. This applied both to normal and DFA matching.
656    
657    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
658        /^[^d]*?$/8 failed to match "abc".
659    
660    16. Added a missing copyright notice to pcrecpp_internal.h.
661    
662    17. Make it more clear in the documentation that values returned from
663        pcre_exec() in ovector are byte offsets, not character counts.
664    
665    18. Tidied a few places to stop certain compilers from issuing warnings.
666    
667    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
668        supplied by Stefan Weber. I made a further small update for 7.8 because
669        there is a change of source arrangements: the pcre_searchfuncs.c module is
670        replaced by pcre_ucd.c.
671    
672    
673    Version 7.7 07-May-08
674    ---------------------
675    
676    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
677        a string to a long long, pretend we don't even have a long long." This is
678        done by checking for the strtoq, strtoll, and _strtoi64 functions.
679    
680    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
681        pre-7.6 versions, which defined a global no_arg variable instead of putting
682        it in the RE class. (See also #8 below.)
683    
684    3.  Remove a line of dead code, identified by coverity and reported by Nuno
685        Lopes.
686    
687    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
688    
689        (1) The include/exclude patterns were being applied to the whole pathnames
690            of files, instead of just to the final components.
691    
692        (2) If there was more than one level of directory, the subdirectories were
693            skipped unless they satisfied the include/exclude conditions. This is
694            inconsistent with GNU grep (and could even be seen as contrary to the
695            pcregrep specification - which I improved to make it absolutely clear).
696            The action now is always to scan all levels of directory, and just
697            apply the include/exclude patterns to regular files.
698    
699    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
700        --exclude_dir in the tests to avoid scanning .svn directories.
701    
702    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
703        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
704        doesn't support NULs in patterns.
705    
706    7.  Added some missing "const"s to declarations of static tables in
707        pcre_compile.c and pcre_dfa_exec.c.
708    
709    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
710        caused by fix #2  above. (Subsequently also a second patch to fix the
711        first patch. And a third patch - this was a messy problem.)
712    
713    9.  Applied Craig's patch to remove the use of push_back().
714    
715    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
716        matching function regexec().
717    
718    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
719        which, however, unlike Perl's \g{...}, are subroutine calls, not back
720        references. PCRE supports relative numbers with this syntax (I don't think
721        Oniguruma does).
722    
723    12. Previously, a group with a zero repeat such as (...){0} was completely
724        omitted from the compiled regex. However, this means that if the group
725        was called as a subroutine from elsewhere in the pattern, things went wrong
726        (an internal error was given). Such groups are now left in the compiled
727        pattern, with a new opcode that causes them to be skipped at execution
728        time.
729    
730    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
731        to the way PCRE behaves:
732    
733        (a) A lone ] character is dis-allowed (Perl treats it as data).
734    
735        (b) A back reference to an unmatched subpattern matches an empty string
736            (Perl fails the current match path).
737    
738        (c) A data ] in a character class must be notated as \] because if the
739            first data character in a class is ], it defines an empty class. (In
740            Perl it is not possible to have an empty class.) The empty class []
741            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
742            The negative empty class [^] matches any one character, independently
743            of the DOTALL setting.
744    
745    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
746        non-existent subpattern following a character class starting with ']' and
747        containing () gave an internal compiling error instead of "reference to
748        non-existent subpattern". Fortunately, when the pattern did exist, the
749        compiled code was correct. (When scanning forwards to check for the
750        existencd of the subpattern, it was treating the data ']' as terminating
751        the class, so got the count wrong. When actually compiling, the reference
752        was subsequently set up correctly.)
753    
754    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
755        it was being rejected as not supported by pcre_dfa_exec(), even though
756        other assertions are supported. I have made pcre_dfa_exec() support
757        (*FAIL).
758    
759    16. The implementation of 13c above involved the invention of a new opcode,
760        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
761        cannot be changed at match time, I realized I could make a small
762        improvement to matching performance by compiling OP_ALLANY instead of
763        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
764        on the OP_ANY path.
765    
766    17. Compiling pcretest on Windows with readline support failed without the
767        following two fixes: (1) Make the unistd.h include conditional on
768        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
769    
770    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
771        ncurses library to be included for pcretest when ReadLine support is
772        requested, but also to allow for it to be overridden. This patch came from
773        Daniel Bergström.
774    
775    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
776        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
777        any errors with the current Unicode tables. Thanks to Peter Kankowski for
778        spotting this.
779    
780    
781    Version 7.6 28-Jan-08
782    ---------------------
783    
784    1.  A character class containing a very large number of characters with
785        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
786        overflow.
787    
788    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
789        HAVE_LONG_LONG is not defined.
790    
791    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
792        bring them up to date and include new features. This patch includes:
793    
794        - Fixed PH's badly added libz and libbz2 support.
795        - Fixed a problem with static linking.
796        - Added pcredemo. [But later removed - see 7 below.]
797        - Fixed dftables problem and added an option.
798        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
799            HAVE_LONG_LONG.
800        - Added readline support for pcretest.
801        - Added an listing of the option settings after cmake has run.
802    
803    4.  A user submitted a patch to Makefile that makes it easy to create
804        "pcre.dll" under mingw when using Configure/Make. I added stuff to
805        Makefile.am that cause it to include this special target, without
806        affecting anything else. Note that the same mingw target plus all
807        the other distribution libraries and programs are now supported
808        when configuring with CMake (see 6 below) instead of with
809        Configure/Make.
810    
811    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
812        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
813        exported in the Windows port". It has not yet been confirmed that the patch
814        solves the problem, but it does no harm.
815    
816    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
817        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
818        with CMake, and also correct the comment about stack recursion.
819    
820    7.  Remove the automatic building of pcredemo from the ./configure system and
821        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
822        of a program that users should build themselves after PCRE is installed, so
823        building it automatically is not really right. What is more, it gave
824        trouble in some build environments.
825    
826    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
827    
828    
829    Version 7.5 10-Jan-08
830    ---------------------
831    
832    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
833        values in parens when parsing an RE using the C++ wrapper."
834    
835    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
836        Characters greater than 255 were excluded from the class instead of being
837        included.
838    
839    3.  The same bug as (2) above applied to negated POSIX classes such as
840        [:^space:].
841    
842    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
843        defined or documented. It seems to have been a typo for PCRE_STATIC, so
844        I have changed it.
845    
846    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
847        first named subpattern) and a construct such as (?&a) would reference the
848        first named subpattern whose name started with "a" (in other words, the
849        length check was missing). Both these problems are fixed. "Subpattern name
850        expected" is now given for (?&) (a zero-length name), and this patch also
851        makes it give the same error for \k'' (previously it complained that that
852        was a reference to a non-existent subpattern).
853    
854    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
855        this is right because (?- can be followed by option settings as well as by
856        digits. I have, however, made the messages clearer.
857    
858    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
859        than the number used in the conditional) now cause a compile-time error.
860        This is actually not compatible with Perl, which accepts such patterns, but
861        treats the conditional as always being FALSE (as PCRE used to), but it
862        seems to me that giving a diagnostic is better.
863    
864    8.  Change "alphameric" to the more common word "alphanumeric" in comments
865        and messages.
866    
867    9.  Fix two occurrences of "backslash" in comments that should have been
868        "backspace".
869    
870    10. Remove two redundant lines of code that can never be obeyed (their function
871        was moved elsewhere).
872    
873    11. The program that makes PCRE's Unicode character property table had a bug
874        which caused it to generate incorrect table entries for sequences of
875        characters that have the same character type, but are in different scripts.
876        It amalgamated them into a single range, with the script of the first of
877        them. In other words, some characters were in the wrong script. There were
878        thirteen such cases, affecting characters in the following ranges:
879    
880          U+002b0 - U+002c1
881          U+0060c - U+0060d
882          U+0061e - U+00612
883          U+0064b - U+0065e
884          U+0074d - U+0076d
885          U+01800 - U+01805
886          U+01d00 - U+01d77
887          U+01d9b - U+01dbf
888          U+0200b - U+0200f
889          U+030fc - U+030fe
890          U+03260 - U+0327f
891          U+0fb46 - U+0fbb1
892          U+10450 - U+1049d
893    
894    12. The -o option (show only the matching part of a line) for pcregrep was not
895        compatible with GNU grep in that, if there was more than one match in a
896        line, it showed only the first of them. It now behaves in the same way as
897        GNU grep.
898    
899    13. If the -o and -v options were combined for pcregrep, it printed a blank
900        line for every non-matching line. GNU grep prints nothing, and pcregrep now
901        does the same. The return code can be used to tell if there were any
902        non-matching lines.
903    
904    14. Added --file-offsets and --line-offsets to pcregrep.
905    
906    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
907        infinitely looping recursion. The bug was that positive lookaheads were not
908        being skipped when checking for a possible empty match (negative lookaheads
909        and both kinds of lookbehind were skipped).
910    
911    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
912        inclusion of <windows.h> to before rather than after the definition of
913        INVALID_FILE_ATTRIBUTES (patch from David Byron).
914    
915    17. Specifying a possessive quantifier with a specific limit for a Unicode
916        character property caused pcre_compile() to compile bad code, which led at
917        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
918        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
919        caused the error; without that there was no problem.
920    
921    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
922    
923    19. Added --enable-pcretest-libreadline.
924    
925    20. In pcrecpp.cc, the variable 'count' was incremented twice in
926        RE::GlobalReplace(). As a result, the number of replacements returned was
927        double what it should be. I removed one of the increments, but Craig sent a
928        later patch that removed the other one (the right fix) and added unit tests
929        that check the return values (which was not done before).
930    
931    21. Several CMake things:
932    
933        (1) Arranged that, when cmake is used on Unix, the libraries end up with
934            the names libpcre and libpcreposix, not just pcre and pcreposix.
935    
936        (2) The above change means that pcretest and pcregrep are now correctly
937            linked with the newly-built libraries, not previously installed ones.
938    
939        (3) Added PCRE_SUPPORT_LIBREADLINE, PCRE_SUPPORT_LIBZ, PCRE_SUPPORT_LIBBZ2.
940    
941    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
942        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
943        UTF-8 newline character). The key issue is that the pattern starts .*;
944        this means that the match must be either at the beginning, or after a
945        newline. The bug was in the code for advancing after a failed match and
946        checking that the new position followed a newline. It was not taking
947        account of UTF-8 characters correctly.
948    
949    23. PCRE was behaving differently from Perl in the way it recognized POSIX
950        character classes. PCRE was not treating the sequence [:...:] as a
951        character class unless the ... were all letters. Perl, however, seems to
952        allow any characters between [: and :], though of course it rejects as
953        unknown any "names" that contain non-letters, because all the known class
954        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
955        for example, whereas PCRE did not - it did not recognize a POSIX character
956        class. This seemed a bit dangerous, so the code has been changed to be
957        closer to Perl. The behaviour is not identical to Perl, because PCRE will
958        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
959        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
960        Perl does, and where it didn't before.
961    
962    24. Rewrite so as to remove the single use of %n from pcregrep because in some
963        Windows environments %n is disabled by default.
964    
965    
966    Version 7.4 21-Sep-07
967    ---------------------
968    
969    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
970        means that a class such as [\s] counted as "explicit reference to CR or
971        LF". That isn't really right - the whole point of the change was to try to
972        help when there was an actual mention of one of the two characters. So now
973        the change happens only if \r or \n (or a literal CR or LF) character is
974        encountered.
975    
976    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
977        of both had grown to the point where there were only 3 bits left.
978        Fortunately, there was spare space in the data structure, and so I have
979        moved the internal flags into a new 16-bit field to free up more option
980        bits.
981    
982    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
983        but did not set the internal JCHANGED flag - either of these is enough to
984        control the way the "get" function works - but the PCRE_INFO_JCHANGED
985        facility is supposed to tell if (?J) was ever used, so now (?J) at the
986        start sets both bits.
987    
988    4.  Added options (at build time, compile time, exec time) to change \R from
989        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
990    
991    5.  doc/pcresyntax.html was missing from the distribution.
992    
993    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
994        compatibility, even though it is no longer used.
995    
996    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
997        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
998        windows.h file is present (where different names are used). [This was
999        reversed later after testing - see 16 below.]
1000    
1001    8.  Changed all #include <config.h> to #include "config.h". There were also
1002        some further <pcre.h> cases that I changed to "pcre.h".
1003    
1004    9.  When pcregrep was used with the --colour option, it missed the line ending
1005        sequence off the lines that it output.
1006    
1007    10. It was pointed out to me that arrays of string pointers cause lots of
1008        relocations when a shared library is dynamically loaded. A technique of
1009        using a single long string with a table of offsets can drastically reduce
1010        these. I have refactored PCRE in four places to do this. The result is
1011        dramatic:
1012    
1013          Originally:                          290
1014          After changing UCP table:            187
1015          After changing error message table:   43
1016          After changing table of "verbs"       36
1017          After changing table of Posix names   22
1018    
1019        Thanks to the folks working on Gregex for glib for this insight.
1020    
1021    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
1022        unicode-properties was also set.
1023    
1024    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
1025    
1026    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
1027        checked only for CRLF.
1028    
1029    14. Added casts to pcretest.c to avoid compiler warnings.
1030    
1031    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
1032    
1033    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
1034        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
1035        entirely. This removes changes made in 7 above.
1036    
1037    17. The CMake files have been updated, and there is now more information about
1038        building with CMake in the NON-UNIX-USE document.
1039    
1040    
1041    Version 7.3 28-Aug-07
1042    ---------------------
1043    
1044     1. In the rejigging of the build system that eventually resulted in 7.1, the
1045        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
1046        brackets there is not right, since it causes compilers to look for an
1047        installed pcre.h, not the version that is in the source that is being
1048        compiled (which of course may be different). I have changed it back to:
1049    
1050          #include "pcre.h"
1051    
1052        I have a vague recollection that the change was concerned with compiling in
1053        different directories, but in the new build system, that is taken care of
1054        by the VPATH setting the Makefile.
1055    
1056     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
1057        when the subject happened to end in the byte 0x85 (e.g. if the last
1058        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
1059        characters but of course it shouldn't be taken as a newline when it is part
1060        of another character. The bug was that, for an unlimited repeat of . in
1061        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
1062        characters when looking for a newline.
1063    
1064     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
1065    
1066     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
1067        in debug output.
1068    
1069     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
1070        long printing in the pcrecpp unittest when running under MinGW.
1071    
1072     6. ESC_K was left out of the EBCDIC table.
1073    
1074     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
1075        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
1076        limit also applies to "virtual nesting" when a pattern is recursive, and in
1077        this case 1000 isn't so big. I have been able to remove this limit at the
1078        expense of backing off one optimization in certain circumstances. Normally,
1079        when pcre_exec() would call its internal match() function recursively and
1080        immediately return the result unconditionally, it uses a "tail recursion"
1081        feature to save stack. However, when a subpattern that can match an empty
1082        string has an unlimited repetition quantifier, it no longer makes this
1083        optimization. That gives it a stack frame in which to save the data for
1084        checking that an empty string has been matched. Previously this was taken
1085        from the 1000-entry workspace that had been reserved. So now there is no
1086        explicit limit, but more stack is used.
1087    
1088     8. Applied Daniel's patches to solve problems with the import/export magic
1089        syntax that is required for Windows, and which was going wrong for the
1090        pcreposix and pcrecpp parts of the library. These were overlooked when this
1091        problem was solved for the main library.
1092    
1093     9. There were some crude static tests to avoid integer overflow when computing
1094        the size of patterns that contain repeated groups with explicit upper
1095        limits. As the maximum quantifier is 65535, the maximum group length was
1096        set at 30,000 so that the product of these two numbers did not overflow a
1097        32-bit integer. However, it turns out that people want to use groups that
1098        are longer than 30,000 bytes (though not repeat them that many times).
1099        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
1100        made it possible to implement the integer overflow checks in a much more
1101        dynamic way, which I have now done. The artificial limitation on group
1102        length has been removed - we now have only the limit on the total length of
1103        the compiled pattern, which depends on the LINK_SIZE setting.
1104    
1105    10. Fixed a bug in the documentation for get/copy named substring when
1106        duplicate names are permitted. If none of the named substrings are set, the
1107        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
1108        empty string.
1109    
1110    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
1111        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
1112        because the ] is interpreted as the first data character and the
1113        terminating ] is not found. PCRE has been made compatible with Perl in this
1114        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
1115        cause memory overwriting.
1116    
1117    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
1118        string has been matched (to stop an infinite loop). It was not recognizing
1119        a conditional subpattern that could match an empty string if that
1120        subpattern was within another subpattern. For example, it looped when
1121        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
1122        condition was not nested. This bug has been fixed.
1123    
1124    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
1125        past the start of the subject in the presence of bytes with the top bit
1126        set, for example "\x8aBCD".
1127    
1128    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
1129        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
1130    
1131    14. Optimized (?!) to (*FAIL).
1132    
1133    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
1134        This restricts code points to be within the range 0 to 0x10FFFF, excluding
1135        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
1136        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
1137        does: it's just the validity check that is more restrictive.
1138    
1139    16. Inserted checks for integer overflows during escape sequence (backslash)
1140        processing, and also fixed erroneous offset values for syntax errors during
1141        backslash processing.
1142    
1143    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
1144        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
1145    
1146    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
1147        caused an overrun.
1148    
1149    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
1150        something other than just ASCII characters) inside a group that had an
1151        unlimited repeat caused a loop at compile time (while checking to see
1152        whether the group could match an empty string).
1153    
1154    20. Debugging a pattern containing \p or \P could cause a crash. For example,
1155        [\P{Any}] did so. (Error in the code for printing property names.)
1156    
1157    21. An orphan \E inside a character class could cause a crash.
1158    
1159    22. A repeated capturing bracket such as (A)? could cause a wild memory
1160        reference during compilation.
1161    
1162    23. There are several functions in pcre_compile() that scan along a compiled
1163        expression for various reasons (e.g. to see if it's fixed length for look
1164        behind). There were bugs in these functions when a repeated \p or \P was
1165        present in the pattern. These operators have additional parameters compared
1166        with \d, etc, and these were not being taken into account when moving along
1167        the compiled data. Specifically:
1168    
1169        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
1170            length.
1171    
1172        (b) An item such as \pL+ within a repeated group could cause crashes or
1173            loops.
1174    
1175        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
1176            "reference to non-existent subpattern" error.
1177    
1178        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
1179    
1180    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
1181        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
1182    
1183    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
1184    
1185    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
1186        character were causing crashes (broken optimization).
1187    
1188    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
1189        \p or \P) caused a compile-time loop.
1190    
1191    28. More problems have arisen in unanchored patterns when CRLF is a valid line
1192        break. For example, the unstudied pattern [\r\n]A does not match the string
1193        "\r\nA" because change 7.0/46 below moves the current point on by two
1194        characters after failing to match at the start. However, the pattern \nA
1195        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
1196        the same is true. There doesn't seem any very clean way out of this, but
1197        what I have chosen to do makes the common cases work: PCRE now takes note
1198        of whether there can be an explicit match for \r or \n anywhere in the
1199        pattern, and if so, 7.0/46 no longer applies. As part of this change,
1200        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
1201        pattern has explicit CR or LF references.
1202    
1203    29. Added (*CR) etc for changing newline setting at start of pattern.
1204    
1205    
1206    Version 7.2 19-Jun-07
1207    ---------------------
1208    
1209     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
1210        which is apparently normally available under Windows.
1211    
1212     2. Re-jig the pcregrep tests with different newline settings in an attempt
1213        to make them independent of the local environment's newline setting.
1214    
1215     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
1216    
1217     4. Some of the "internals" tests were previously cut out when the link size
1218        was not 2, because the output contained actual offsets. The recent new
1219        "Z" feature of pcretest means that these can be cut out, making the tests
1220        usable with all link sizes.
1221    
1222     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
1223        stack recursion. This gives a massive performance boost under BSD, but just
1224        a small improvement under Linux. However, it saves one field in the frame
1225        in all cases.
1226    
1227     6. Added more features from the forthcoming Perl 5.10:
1228    
1229        (a) (?-n) (where n is a string of digits) is a relative subroutine or
1230            recursion call. It refers to the nth most recently opened parentheses.
1231    
1232        (b) (?+n) is also a relative subroutine call; it refers to the nth next
1233            to be opened parentheses.
1234    
1235        (c) Conditions that refer to capturing parentheses can be specified
1236            relatively, for example, (?(-2)... or (?(+3)...
1237    
1238        (d) \K resets the start of the current match so that everything before
1239            is not part of it.
1240    
1241        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
1242    
1243        (f) \g{name} is another synonym - part of Perl 5.10's unification of
1244            reference syntax.
1245    
1246        (g) (?| introduces a group in which the numbering of parentheses in each
1247            alternative starts with the same number.
1248    
1249        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
1250    
1251     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
1252        PCRE_INFO_JCHANGED.
1253    
1254     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
1255        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
1256        for detecting groups that can match an empty string.
1257    
1258     9. A pattern with a very large number of alternatives (more than several
1259        hundred) was running out of internal workspace during the pre-compile
1260        phase, where pcre_compile() figures out how much memory will be needed. A
1261        bit of new cunning has reduced the workspace needed for groups with
1262        alternatives. The 1000-alternative test pattern now uses 12 bytes of
1263        workspace instead of running out of the 4096 that are available.
1264    
1265    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
1266    
1267    11. Applied patch from Google to remove an optimization that didn't quite work.
1268        The report of the bug said:
1269    
1270          pcrecpp::RE("a*").FullMatch("aaa") matches, while
1271          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
1272          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
1273    
1274    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
1275        it matched the wrong number of bytes.
1276    
1277    
1278    Version 7.1 24-Apr-07
1279    ---------------------
1280    
1281     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
1282        that is more "standard", making use of automake and other Autotools. There
1283        is some re-arrangement of the files and adjustment of comments consequent
1284        on this.
1285    
1286     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
1287        for recursive directory scanning broke on some systems because the files
1288        are not scanned in any specific order and on different systems the order
1289        was different. A call to "sort" has been inserted into RunGrepTest for the
1290        approprate test as a short-term fix. In the longer term there may be an
1291        alternative.
1292    
1293     3. I had an email from Eric Raymond about problems translating some of PCRE's
1294        man pages to HTML (despite the fact that I distribute HTML pages, some
1295        people do their own conversions for various reasons). The problems
1296        concerned the use of low-level troff macros .br and .in. I have therefore
1297        removed all such uses from the man pages (some were redundant, some could
1298        be replaced by .nf/.fi pairs). The 132html script that I use to generate
1299        HTML has been updated to handle .nf/.fi and to complain if it encounters
1300        .br or .in.
1301    
1302     4. Updated comments in configure.ac that get placed in config.h.in and also
1303        arranged for config.h to be included in the distribution, with the name
1304        config.h.generic, for the benefit of those who have to compile without
1305        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
1306    
1307     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
1308        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
1309        makevp.bat for the current PCRE, using the additional files
1310        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
1311    
1312     6. A Windows user reported a minor discrepancy with test 2, which turned out
1313        to be caused by a trailing space on an input line that had got lost in his
1314        copy. The trailing space was an accident, so I've just removed it.
1315    
1316     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
1317        that is needed.
1318    
1319     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
1320        as "const" (a) because they are and (b) because it helps the PHP
1321        maintainers who have recently made a script to detect big data structures
1322        in the php code that should be moved to the .rodata section. I remembered
1323        to update Builducptable as well, so it won't revert if ucptable.h is ever
1324        re-created.
1325    
1326     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
1327        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
1328        order to be able to cut out the UTF-8 tables in the latter when UTF-8
1329        support is not required. This saves 1.5-2K of code, which is important in
1330        some applications.
1331    
1332        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
1333        so as not to refer to the tables, even though these functions will never be
1334        called when UTF-8 support is disabled. Otherwise there are problems with a
1335        shared library.
1336    
1337    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
1338    
1339        (a) It was defining its arguments as char * instead of void *.
1340    
1341        (b) It was assuming that all moves were upwards in memory; this was true
1342            a long time ago when I wrote it, but is no longer the case.
1343    
1344        The emulated memove() is provided for those environments that have neither
1345        memmove() nor bcopy(). I didn't think anyone used it these days, but that
1346        is clearly not the case, as these two bugs were recently reported.
1347    
1348    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
1349        and Detrail to create the HTML documentation, the .txt form of the man
1350        pages, and it removes trailing spaces from listed files. It also creates
1351        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
1352        case, it wraps all the #defines with #ifndefs. This script should be run
1353        before "make dist".
1354    
1355    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
1356        with Unicode property support.
1357    
1358        (a) For a maximizing quantifier, if the two different cases of the
1359            character were of different lengths in their UTF-8 codings (there are
1360            some cases like this - I found 11), and the matching function had to
1361            back up over a mixture of the two cases, it incorrectly assumed they
1362            were both the same length.
1363    
1364        (b) When PCRE was configured to use the heap rather than the stack for
1365            recursion during matching, it was not correctly preserving the data for
1366            the other case of a UTF-8 character when checking ahead for a match
1367            while processing a minimizing repeat. If the check also involved
1368            matching a wide character, but failed, corruption could cause an
1369            erroneous result when trying to check for a repeat of the original
1370            character.
1371    
1372    13. Some tidying changes to the testing mechanism:
1373    
1374        (a) The RunTest script now detects the internal link size and whether there
1375            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
1376            values substituted by "configure". (The RunGrepTest script already did
1377            this for UTF-8.) The configure.ac script no longer substitutes the
1378            relevant variables.
1379    
1380        (b) The debugging options /B and /D in pcretest show the compiled bytecode
1381            with length and offset values. This means that the output is different
1382            for different internal link sizes. Test 2 is skipped for link sizes
1383            other than 2 because of this, bypassing the problem. Unfortunately,
1384            there was also a test in test 3 (the locale tests) that used /B and
1385            failed for link sizes other than 2. Rather than cut the whole test out,
1386            I have added a new /Z option to pcretest that replaces the length and
1387            offset values with spaces. This is now used to make test 3 independent
1388            of link size. (Test 2 will be tidied up later.)
1389    
1390    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
1391        segmentation fault instead of returning the appropriate error message.
1392    
1393    15. In multiline mode when the newline sequence was set to "any", the pattern
1394        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
1395        This doesn't seem right; it now treats the CRLF combination as the line
1396        ending, and so does not match in that case. It's only a pattern such as ^$
1397        that would hit this one: something like ^ABC$ would have failed after \r
1398        and then tried again after \r\n.
1399    
1400    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
1401        in an attempt to make files that differ only in their line terminators
1402        compare equal. This works on Linux.
1403    
1404    17. Under certain error circumstances pcregrep might try to free random memory
1405        as it exited. This is now fixed, thanks to valgrind.
1406    
1407    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
1408        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
1409        was because its rules for how to advance for /g after matching an empty
1410        string at the end of a line did not allow for this case. They now check for
1411        it specially.
1412    
1413    20. pcretest is supposed to handle patterns and data of any length, by
1414        extending its buffers when necessary. It was getting this wrong when the
1415        buffer for a data line had to be extended.
1416    
1417    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
1418        CRLF as a newline sequence.
1419    
1420    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
1421        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
1422        I have nevertheless tidied it up.
1423    
1424    23. Added some casts to kill warnings from HP-UX ia64 compiler.
1425    
1426    24. Added a man page for pcre-config.
1427    
1428    
1429    Version 7.0 19-Dec-06
1430    ---------------------
1431    
1432     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
1433        moving to gcc 4.1.1.
1434    
1435     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
1436        sys/time.h, which is documented as needed for this function. It doesn't
1437        seem to matter on Linux, but it showed up on some releases of OS X.
1438    
1439     3. It seems that there are systems where bytes whose values are greater than
1440        127 match isprint() in the "C" locale. The "C" locale should be the
1441        default when a C program starts up. In most systems, only ASCII printing
1442        characters match isprint(). This difference caused the output from pcretest
1443        to vary, making some of the tests fail. I have changed pcretest so that:
1444    
1445        (a) When it is outputting text in the compiled version of a pattern, bytes
1446            other than 32-126 are always shown as hex escapes.
1447    
1448        (b) When it is outputting text that is a matched part of a subject string,
1449            it does the same, unless a different locale has been set for the match
1450            (using the /L modifier). In this case, it uses isprint() to decide.
1451    
1452     4. Fixed a major bug that caused incorrect computation of the amount of memory
1453        required for a compiled pattern when options that changed within the
1454        pattern affected the logic of the preliminary scan that determines the
1455        length. The relevant options are -x, and -i in UTF-8 mode. The result was
1456        that the computed length was too small. The symptoms of this bug were
1457        either the PCRE error "internal error: code overflow" from pcre_compile(),
1458        or a glibc crash with a message such as "pcretest: free(): invalid next
1459        size (fast)". Examples of patterns that provoked this bug (shown in
1460        pcretest format) are:
1461    
1462          /(?-x: )/x
1463          /(?x)(?-x: \s*#\s*)/
1464          /((?i)[\x{c0}])/8
1465          /(?i:[\x{c0}])/8
1466    
1467        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
1468        is now done differently.
1469    
1470     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
1471        wrapper classes; (b) implement a new function in the C++ scanner that is
1472        more efficient than the old way of doing things because it avoids levels of
1473        recursion in the regex matching; (c) add a paragraph to the documentation
1474        for the FullMatch() function.
1475    
1476     6. The escape sequence \n was being treated as whatever was defined as
1477        "newline". Not only was this contrary to the documentation, which states
1478        that \n is character 10 (hex 0A), but it also went horribly wrong when
1479        "newline" was defined as CRLF. This has been fixed.
1480    
1481     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
1482        was being set to -1 for the "end of line" case (supposedly a value that no
1483        character can have). Though this value is never used (the check for end of
1484        line is "zero bytes in current character"), it caused compiler complaints.
1485        I've changed it to 0xffffffff.
1486    
1487     8. In pcre_version.c, the version string was being built by a sequence of
1488        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
1489        string (as it is for production releases) called a macro with an empty
1490        argument. The C standard says the result of this is undefined. The gcc
1491        compiler treats it as an empty string (which was what was wanted) but it is
1492        reported that Visual C gives an error. The source has been hacked around to
1493        avoid this problem.
1494    
1495     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
1496        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
1497        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
1498        of them did).
1499    
1500    10. Originally, pcretest opened its input and output without "b"; then I was
1501        told that "b" was needed in some environments, so it was added for release
1502        5.0 to both the input and output. (It makes no difference on Unix-like
1503        systems.) Later I was told that it is wrong for the input on Windows. I've
1504        now abstracted the modes into two macros, to make it easier to fiddle with
1505        them, and removed "b" from the input mode under Windows.
1506    
1507    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
1508    
1509    12. Added -help and --help to pcretest as an official way of being reminded
1510        of the options.
1511    
1512    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
1513        and pcrecpp.cc because they annoy compilers at high warning levels.
1514    
1515    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
1516    
1517    15. Fixed an occurrence of == in configure.ac that should have been = (shell
1518        scripts are not C programs :-) and which was not noticed because it works
1519        on Linux.
1520    
1521    16. pcretest is supposed to handle any length of pattern and data line (as one
1522        line or as a continued sequence of lines) by extending its input buffer if
1523        necessary. This feature was broken for very long pattern lines, leading to
1524        a string of junk being passed to pcre_compile() if the pattern was longer
1525        than about 50K.
1526    
1527    17. I have done a major re-factoring of the way pcre_compile() computes the
1528        amount of memory needed for a compiled pattern. Previously, there was code
1529        that made a preliminary scan of the pattern in order to do this. That was
1530        OK when PCRE was new, but as the facilities have expanded, it has become
1531        harder and harder to keep it in step with the real compile phase, and there
1532        have been a number of bugs (see for example, 4 above). I have now found a
1533        cunning way of running the real compile function in a "fake" mode that
1534        enables it to compute how much memory it would need, while actually only
1535        ever using a few hundred bytes of working memory and without too many
1536        tests of the mode. This should make future maintenance and development
1537        easier. A side effect of this work is that the limit of 200 on the nesting
1538        depth of parentheses has been removed (though this was never a serious
1539        limitation, I suspect). However, there is a downside: pcre_compile() now
1540        runs more slowly than before (30% or more, depending on the pattern). I
1541        hope this isn't a big issue. There is no effect on runtime performance.
1542    
1543    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
1544        newline (only possible for the last line of a file) and it was a
1545        pattern that set a locale (followed by /Lsomething), pcretest crashed.
1546    
1547    19. Added additional timing features to pcretest. (1) The -tm option now times
1548        matching only, not compiling. (2) Both -t and -tm can be followed, as a
1549        separate command line item, by a number that specifies the number of
1550        repeats to use when timing. The default is 50000; this gives better
1551        precision, but takes uncomfortably long for very large patterns.
1552    
1553    20. Extended pcre_study() to be more clever in cases where a branch of a
1554        subpattern has no definite first character. For example, (a*|b*)[cd] would
1555        previously give no result from pcre_study(). Now it recognizes that the
1556        first character must be a, b, c, or d.
1557    
1558    21. There was an incorrect error "recursive call could loop indefinitely" if
1559        a subpattern (or the entire pattern) that was being tested for matching an
1560        empty string contained only one non-empty item after a nested subpattern.
1561        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
1562        incorrectly, because the \d was being skipped in the check.
1563    
1564    22. The pcretest program now has a new pattern option /B and a command line
1565        option -b, which is equivalent to adding /B to every pattern. This causes
1566        it to show the compiled bytecode, without the additional information that
1567        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
1568        is the same as /B/I).
1569    
1570    23. A new optimization is now able automatically to treat some sequences such
1571        as a*b as a*+b. More specifically, if something simple (such as a character
1572        or a simple class like \d) has an unlimited quantifier, and is followed by
1573        something that cannot possibly match the quantified thing, the quantifier
1574        is automatically "possessified".
1575    
1576    24. A recursive reference to a subpattern whose number was greater than 39
1577        went wrong under certain circumstances in UTF-8 mode. This bug could also
1578        have affected the operation of pcre_study().
1579    
1580    25. Realized that a little bit of performance could be had by replacing
1581        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
1582    
1583    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
1584    
1585    27. Possessive quantifiers such as a++ were previously implemented by turning
1586        them into atomic groups such as ($>a+). Now they have their own opcodes,
1587        which improves performance. This includes the automatically created ones
1588        from 23 above.
1589    
1590    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
1591        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
1592        the first matched character to be a colon. This applied both to named and
1593        numbered groups.
1594    
1595    29. The ucpinternal.h header file was missing its idempotency #ifdef.
1596    
1597    30. I was sent a "project" file called libpcre.a.dev which I understand makes
1598        building PCRE on Windows easier, so I have included it in the distribution.
1599    
1600    31. There is now a check in pcretest against a ridiculously large number being
1601        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
1602        loop, the loop is abandoned.
1603    
1604    32. Forward references to subpatterns in conditions such as (?(2)...) where
1605        subpattern 2 is defined later cause pcre_compile() to search forwards in
1606        the pattern for the relevant set of parentheses. This search went wrong
1607        when there were unescaped parentheses in a character class, parentheses
1608        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
1609    
1610    33. "Subroutine" calls and backreferences were previously restricted to
1611        referencing subpatterns earlier in the regex. This restriction has now
1612        been removed.
1613    
1614    34. Added a number of extra features that are going to be in Perl 5.10. On the
1615        whole, these are just syntactic alternatives for features that PCRE had
1616        previously implemented using the Python syntax or my own invention. The
1617        other formats are all retained for compatibility.
1618    
1619        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
1620            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
1621            also .NET compatible.
1622    
1623        (b) A recursion or subroutine call to a named group can now be defined as
1624            (?&name) as well as (?P>name).
1625    
1626        (c) A backreference to a named group can now be defined as \k<name> or
1627            \k'name' as well as (?P=name). The new forms, as well as being in Perl
1628            5.10, are also .NET compatible.
1629    
1630        (d) A conditional reference to a named group can now use the syntax
1631            (?(<name>) or (?('name') as well as (?(name).
1632    
1633        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
1634            groups (named and numbered) that are never evaluated inline, but can be
1635            called as "subroutines" from elsewhere. In effect, the DEFINE condition
1636            is always false. There may be only one alternative in such a group.
1637    
1638        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
1639            as the simple (?(R). The condition is true only if the most recent
1640            recursion is that of the given number or name. It does not search out
1641            through the entire recursion stack.
1642    
1643        (g) The escape \gN or \g{N} has been added, where N is a positive or
1644            negative number, specifying an absolute or relative reference.
1645    
1646    35. Tidied to get rid of some further signed/unsigned compiler warnings and
1647        some "unreachable code" warnings.
1648    
1649    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
1650        things, this adds five new scripts.
1651    
1652    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
1653        There were also incompatibilities regarding the handling of \Q..\E inside
1654        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
1655        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
1656    
1657    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
1658        matches an empty string, and forcibly breaks the loop. There were bugs in
1659        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
1660        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
1661        separate and independent bugs (that affected different cases) have been
1662        fixed.
1663    
1664    39. Refactored the code to abolish the use of different opcodes for small
1665        capturing bracket numbers. This is a tidy that I avoided doing when I
1666        removed the limit on the number of capturing brackets for 3.5 back in 2001.
1667        The new approach is not only tidier, it makes it possible to reduce the
1668        memory needed to fix the previous bug (38).
1669    
1670    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
1671        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
1672        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
1673        mode.
1674    
1675    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
1676        report.
1677    
1678    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
1679        copy construction and assignment in the C++ wrapper.
1680    
1681    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
1682        couple of bugs that could have given wrong results in the "--newline=crlf"
1683        case.
1684    
1685    44. Added a number of casts and did some reorganization of signed/unsigned int
1686        variables following suggestions from Dair Grant. Also renamed the variable
1687        "this" as "item" because it is a C++ keyword.
1688    
1689    45. Arranged for dftables to add
1690    
1691          #include "pcre_internal.h"
1692    
1693        to pcre_chartables.c because without it, gcc 4.x may remove the array
1694        definition from the final binary if PCRE is built into a static library and
1695        dead code stripping is activated.
1696    
1697    46. For an unanchored pattern, if a match attempt fails at the start of a
1698        newline sequence, and the newline setting is CRLF or ANY, and the next two
1699        characters are CRLF, advance by two characters instead of one.
1700    
1701    
1702    Version 6.7 04-Jul-06
1703    ---------------------
1704    
1705     1. In order to handle tests when input lines are enormously long, pcretest has
1706        been re-factored so that it automatically extends its buffers when
1707        necessary. The code is crude, but this _is_ just a test program. The
1708        default size has been increased from 32K to 50K.
1709    
1710     2. The code in pcre_study() was using the value of the re argument before
1711        testing it for NULL. (Of course, in any sensible call of the function, it
1712        won't be NULL.)
1713    
1714     3. The memmove() emulation function in pcre_internal.h, which is used on
1715        systems that lack both memmove() and bcopy() - that is, hardly ever -
1716        was missing a "static" storage class specifier.
1717    
1718     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1719        containing an extended class (one that cannot be represented by a bitmap
1720        because it contains high-valued characters or Unicode property items, e.g.
1721        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1722        pattern, but PCRE should not loop if you do not (it no longer does).
1723        [Detail: two cases were found: (a) a repeated subpattern containing an
1724        extended class; (b) a recursive reference to a subpattern that followed a
1725        previous extended class. It wasn't skipping over the extended class
1726        correctly when UTF-8 mode was not set.]
1727    
1728     5. A negated single-character class was not being recognized as fixed-length
1729        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1730        compile error "lookbehind assertion is not fixed length".
1731    
1732     6. The RunPerlTest auxiliary script was showing an unexpected difference
1733        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1734        write a Perl script that can interpret lines of an input file either as
1735        byte characters or as UTF-8, which is what "perltest" was being required to
1736        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1737        can't do is switch easily at run time between having the "use utf8;" pragma
1738        or not. In the end, I fudged it by using the RunPerlTest script to insert
1739        "use utf8;" explicitly for the UTF-8 tests.
1740    
1741     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1742        the end of the subject string, contrary to the documentation and to what
1743        Perl does. This was true of both matching functions. Now it matches only at
1744        the start of the subject and immediately after *internal* newlines.
1745    
1746     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1747        a pointer to an int instead of a pointer to an unsigned long int. This
1748        caused problems on 64-bit systems.
1749    
1750     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1751        instance of the 'standard' template library not being so standard".
1752    
1753    10. There was no check on the number of named subpatterns nor the maximum
1754        length of a subpattern name. The product of these values is used to compute
1755        the size of the memory block for a compiled pattern. By supplying a very
1756        long subpattern name and a large number of named subpatterns, the size
1757        computation could be caused to overflow. This is now prevented by limiting
1758        the length of names to 32 characters, and the number of named subpatterns
1759        to 10,000.
1760    
1761    11. Subpatterns that are repeated with specific counts have to be replicated in
1762        the compiled pattern. The size of memory for this was computed from the
1763        length of the subpattern and the repeat count. The latter is limited to
1764        65535, but there was no limit on the former, meaning that integer overflow
1765        could in principle occur. The compiled length of a repeated subpattern is
1766        now limited to 30,000 bytes in order to prevent this.
1767    
1768    12. Added the optional facility to have named substrings with the same name.
1769    
1770    13. Added the ability to use a named substring as a condition, using the
1771        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1772        are numbers (not recommended). Forward references are permitted.
1773    
1774    14. Added forward references in named backreferences (if you see what I mean).
1775    
1776    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1777        pattern could run off the end of the subject. For example, the pattern
1778        "(?s)(.{1,5})"8 did this with the subject "ab".
1779    
1780    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1781        PCRE_CASELESS was set when matching characters that were quantified with ?
1782        or *.
1783    
1784    17. A character class other than a single negated character that had a minimum
1785        but no maximum quantifier - for example [ab]{6,} - was not handled
1786        correctly by pce_dfa_exec(). It would match only one character.
1787    
1788    18. A valid (though odd) pattern that looked like a POSIX character
1789        class but used an invalid character after [ (for example [[,abc,]]) caused
1790        pcre_compile() to give the error "Failed: internal error: code overflow" or
1791        in some cases to crash with a glibc free() error. This could even happen if
1792        the pattern terminated after [[ but there just happened to be a sequence of
1793        letters, a binary zero, and a closing ] in the memory that followed.
1794    
1795    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1796        over the years. Originally (before any Unicode support), just the bottom 8
1797        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1798        output from "man perlunicode" includes this:
1799    
1800          The regular expression compiler produces polymorphic opcodes.  That
1801          is, the pattern adapts to the data and automatically switches to
1802          the Unicode character scheme when presented with Unicode data--or
1803          instead uses a traditional byte scheme when presented with byte
1804          data.
1805    
1806        Sadly, a wide octal escape does not cause a switch, and in a string with
1807        no other multibyte characters, these octal escapes are treated as before.
1808        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1809        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1810        Unicode string.
1811    
1812        I have not perpetrated such confusion in PCRE. Up till now, it took just
1813        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1814        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1815        translate to the appropriate multibyte character.
1816    
1817    29. Applied some refactoring to reduce the number of warnings from Microsoft
1818        and Borland compilers. This has included removing the fudge introduced
1819        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1820        a warning about an unused variable.
1821    
1822    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1823        characters since release 4.0, because Perl (from release 5.004) does not.
1824        [Or at least, is documented not to: some releases seem to be in conflict
1825        with the documentation.] However, when a pattern was studied with
1826        pcre_study() and all its branches started with \s, PCRE still included VT
1827        as a possible starting character. Of course, this did no harm; it just
1828        caused an unnecessary match attempt.
1829    
1830    22. Removed a now-redundant internal flag bit that recorded the fact that case
1831        dependency changed within the pattern. This was once needed for "required
1832        byte" processing, but is no longer used. This recovers a now-scarce options
1833        bit. Also moved the least significant internal flag bit to the most-
1834        significant bit of the word, which was not previously used (hangover from
1835        the days when it was an int rather than a uint) to free up another bit for
1836        the future.
1837    
1838    23. Added support for CRLF line endings as well as CR and LF. As well as the
1839        default being selectable at build time, it can now be changed at runtime
1840        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1841        specify that it is scanning data with non-default line endings.
1842    
1843    24. Changed the definition of CXXLINK to make it agree with the definition of
1844        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1845    
1846    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1847        recursions. This makes a big different to stack usage for some patterns.
1848    
1849    26. If a subpattern containing a named recursion or subroutine reference such
1850        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1851        the space required for the compiled pattern went wrong and gave too small a
1852        value. Depending on the environment, this could lead to "Failed: internal
1853        error: code overflow at offset 49" or "glibc detected double free or
1854        corruption" errors.
1855    
1856    27. Applied patches from Google (a) to support the new newline modes and (b) to
1857        advance over multibyte UTF-8 characters in GlobalReplace.
1858    
1859    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1860        difference for some implementation of PCRE in some Windows version.
1861    
1862    29. Added some extra testing facilities to pcretest:
1863    
1864        \q<number>   in a data line sets the "match limit" value
1865        \Q<number>   in a data line sets the "match recursion limt" value
1866        -S <number>  sets the stack size, where <number> is in megabytes
1867    
1868        The -S option isn't available for Windows.
1869    
1870    
1871    Version 6.6 06-Feb-06
1872    ---------------------
1873    
1874     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1875        in pcreposix.h. I have copied the definition from pcre.h.
1876    
1877     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1878        because pcre.h is no longer a built file.
1879    
1880     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1881        not normally included in the compiled code.
1882    
1883    
1884    Version 6.5 01-Feb-06
1885    ---------------------
1886    
1887     1. When using the partial match feature with pcre_dfa_exec(), it was not
1888        anchoring the second and subsequent partial matches at the new starting
1889        point. This could lead to incorrect results. For example, with the pattern
1890        /1234/, partially matching against "123" and then "a4" gave a match.
1891    
1892     2. Changes to pcregrep:
1893    
1894        (a) All non-match returns from pcre_exec() were being treated as failures
1895            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1896            error message is output. Some extra information is given for the
1897            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1898            probably the only errors that are likely to be caused by users (by
1899            specifying a regex that has nested indefinite repeats, for instance).
1900            If there are more than 20 of these errors, pcregrep is abandoned.
1901    
1902        (b) A binary zero was treated as data while matching, but terminated the
1903            output line if it was written out. This has been fixed: binary zeroes
1904            are now no different to any other data bytes.
1905    
1906        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1907            used to set a locale for matching. The --locale=xxxx long option has
1908            been added (no short equivalent) to specify a locale explicitly on the
1909            pcregrep command, overriding the environment variables.
1910    
1911        (d) When -B was used with -n, some line numbers in the output were one less
1912            than they should have been.
1913    
1914        (e) Added the -o (--only-matching) option.
1915    
1916        (f) If -A or -C was used with -c (count only), some lines of context were
1917            accidentally printed for the final match.
1918    
1919        (g) Added the -H (--with-filename) option.
1920    
1921        (h) The combination of options -rh failed to suppress file names for files
1922            that were found from directory arguments.
1923    
1924        (i) Added the -D (--devices) and -d (--directories) options.
1925    
1926        (j) Added the -F (--fixed-strings) option.
1927    
1928        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1929    
1930        (l) Added the --colo(u)r option.
1931    
1932        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1933            is not present by default.
1934    
1935     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1936        items such as (?R) or (?1), when the recursion could match a number of
1937        alternatives. If it matched one of the alternatives, but subsequently,
1938        outside the recursion, there was a failure, the code tried to back up into
1939        the recursion. However, because of the way PCRE is implemented, this is not
1940        possible, and the result was an incorrect result from the match.
1941    
1942        In order to prevent this happening, the specification of recursion has
1943        been changed so that all such subpatterns are automatically treated as
1944        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1945    
1946     4. I had overlooked the fact that, in some locales, there are characters for
1947        which isalpha() is true but neither isupper() nor islower() are true. In
1948        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1949        and ordfeminine) are like this. This affected the treatment of \w and \W
1950        when they appeared in character classes, but not when they appeared outside
1951        a character class. The bit map for "word" characters is now created
1952        separately from the results of isalnum() instead of just taking it from the
1953        upper, lower, and digit maps. (Plus the underscore character, of course.)
1954    
1955     5. The above bug also affected the handling of POSIX character classes such as
1956        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1957        permanent tables. Instead, the bit maps for such a class were previously
1958        created as the appropriate unions of the upper, lower, and digit bitmaps.
1959        Now they are created by subtraction from the [[:word:]] class, which has
1960        its own bitmap.
1961    
1962     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1963        It is created by subtracting the vertical space characters (\x09, \x0a,
1964        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1965        subtraction was done in the overall bitmap for a character class, meaning
1966        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1967        be recognized. This bug has been fixed.
1968    
1969     7. Patches from the folks at Google:
1970    
1971          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1972          real life, but is still worth protecting against".
1973    
1974          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1975          regular expressions".
1976    
1977          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1978          have it.
1979    
1980          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1981          "configure" and the latter not, in order to fix a problem somebody had
1982          with compiling the Arg class on HP-UX.
1983    
1984          (e) Improve the error-handling of the C++ wrapper a little bit.
1985    
1986          (f) New tests for checking recursion limiting.
1987    
1988     8. The pcre_memmove() function, which is used only if the environment does not
1989        have a standard memmove() function (and is therefore rarely compiled),
1990        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1991        returning a result (though PCRE never actually uses the result).
1992    
1993     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1994        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1995        returned instead of calling malloc() with an overflowing number that would
1996        most likely cause subsequent chaos.
1997    
1998    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1999    
2000    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
2001        with this option is matched, the nmatch and pmatch options of regexec() are
2002        ignored.
2003    
2004    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
2005        provided in case anyone wants to the the POSIX interface with UTF-8
2006        strings.
2007    
2008    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
2009        C++ linking (needed for some HP-UX environments).
2010    
2011    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
2012        (unused parameter) and in the pcre_printint() function (omitted "default"
2013        switch label when the default is to do nothing).
2014    
2015    15. Added some code to make it possible, when PCRE is compiled as a C++
2016        library, to replace subject pointers for pcre_exec() with a smart pointer
2017        class, thus making it possible to process discontinuous strings.
2018    
2019    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
2020        much the same function. They were added by different people who were trying
2021        to make PCRE easy to compile on non-Unix systems. It has been suggested
2022        that PCRE_EXPORT be abolished now that there is more automatic apparatus
2023        for compiling on Windows systems. I have therefore replaced it with
2024        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
2025        defaults to "extern" for C or "extern C" for C++, which works fine on
2026        Unix-like systems. It is now possible to override the value of PCRE_DATA_
2027        SCOPE with something explicit in config.h. In addition:
2028    
2029        (a) pcreposix.h still had just "extern" instead of either of these macros;
2030            I have replaced it with PCRE_DATA_SCOPE.
2031    
2032        (b) Functions such as _pcre_xclass(), which are internal to the library,
2033            but external in the C sense, all had PCRE_EXPORT in their definitions.
2034            This is apparently wrong for the Windows case, so I have removed it.
2035            (It makes no difference on Unix-like systems.)
2036    
2037    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
2038        of recursive calls to match(). This is different to MATCH_LIMIT because
2039        that limits the total number of calls to match(), not all of which increase
2040        the depth of recursion. Limiting the recursion depth limits the amount of
2041        stack (or heap if NO_RECURSE is set) that is used. The default can be set
2042        when PCRE is compiled, and changed at run time. A patch from Google adds
2043        this functionality to the C++ interface.
2044    
2045    18. Changes to the handling of Unicode character properties:
2046    
2047        (a) Updated the table to Unicode 4.1.0.
2048    
2049        (b) Recognize characters that are not in the table as "Cn" (undefined).
2050    
2051        (c) I revised the way the table is implemented to a much improved format
2052            which includes recognition of ranges. It now supports the ranges that
2053            are defined in UnicodeData.txt, and it also amalgamates other
2054            characters into ranges. This has reduced the number of entries in the
2055            table from around 16,000 to around 3,000, thus reducing its size
2056            considerably. I realized I did not need to use a tree structure after
2057            all - a binary chop search is just as efficient. Having reduced the
2058            number of entries, I extended their size from 6 bytes to 8 bytes to
2059            allow for more data.
2060    
2061        (d) Added support for Unicode script names via properties such as \p{Han}.
2062    
2063    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
2064        matching that character.
2065    
2066    20. When matching a repeated Unicode property with a minimum greater than zero,
2067        (for example \pL{2,}), PCRE could look past the end of the subject if it
2068        reached it while seeking the minimum number of characters. This could
2069        happen only if some of the characters were more than one byte long, because
2070        there is a check for at least the minimum number of bytes.
2071    
2072    21. Refactored the implementation of \p and \P so as to be more general, to
2073        allow for more different types of property in future. This has changed the
2074        compiled form incompatibly. Anybody with saved compiled patterns that use
2075        \p or \P will have to recompile them.
2076    
2077    22. Added "Any" and "L&" to the supported property types.
2078    
2079    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
2080        but give a compile time error if the value is greater than 0xff.
2081    
2082    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
2083        accidentally not being installed or uninstalled.
2084    
2085    25. The pcre.h file was built from pcre.h.in, but the only changes that were
2086        made were to insert the current release number. This seemed silly, because
2087        it made things harder for people building PCRE on systems that don't run
2088        "configure". I have turned pcre.h into a distributed file, no longer built
2089        by "configure", with the version identification directly included. There is
2090        no longer a pcre.h.in file.
2091    
2092        However, this change necessitated a change to the pcre-config script as
2093        well. It is built from pcre-config.in, and one of the substitutions was the
2094        release number. I have updated configure.ac so that ./configure now finds
2095        the release number by grepping pcre.h.
2096    
2097    26. Added the ability to run the tests under valgrind.
2098    
2099    
2100    Version 6.4 05-Sep-05
2101    ---------------------
2102    
2103     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
2104        "--" to be printed when multiple files were scanned, even when none of the
2105        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
2106        consider it to be a bug, and have restored the previous behaviour.
2107    
2108     2. A couple of code tidies to get rid of compiler warnings.
2109    
2110     3. The pcretest program used to cheat by referring to symbols in the library
2111        whose names begin with _pcre_. These are internal symbols that are not
2112        really supposed to be visible externally, and in some environments it is
2113        possible to suppress them. The cheating is now confined to including
2114        certain files from the library's source, which is a bit cleaner.
2115    
2116     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
2117        file's purpose clearer.
2118    
2119     5. Reorganized pcre_ucp_findchar().
2120    
2121    
2122    Version 6.3 15-Aug-05
2123    ---------------------
2124    
2125     1. The file libpcre.pc.in did not have general read permission in the tarball.
2126    
2127     2. There were some problems when building without C++ support:
2128    
2129        (a) If C++ support was not built, "make install" and "make test" still
2130            tried to test it.
2131    
2132        (b) There were problems when the value of CXX was explicitly set. Some
2133            changes have been made to try to fix these, and ...
2134    
2135        (c) --disable-cpp can now be used to explicitly disable C++ support.
2136    
2137        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
2138            backslash in a target when C++ was disabled. This confuses some
2139            versions of "make", apparently. Using an intermediate variable solves
2140            this. (Same for CPP_LOBJ.)
2141    
2142     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
2143        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
2144        necessary on certain architectures.
2145    
2146     4. Added a setting of -export-symbols-regex to the link command to remove
2147        those symbols that are exported in the C sense, but actually are local
2148        within the library, and not documented. Their names all begin with
2149        "_pcre_". This is not a perfect job, because (a) we have to except some
2150        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
2151        available (and never for static libraries). I have made a note to try to
2152        find a way round (a) in the future.
2153    
2154    
2155    Version 6.2 01-Aug-05
2156    ---------------------
2157    
2158     1. There was no test for integer overflow of quantifier values. A construction
2159        such as {1111111111111111} would give undefined results. What is worse, if
2160        a minimum quantifier for a parenthesized subpattern overflowed and became
2161        negative, the calculation of the memory size went wrong. This could have
2162        led to memory overwriting.
2163    
2164     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
2165    
2166     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
2167        operating environments where this matters.
2168    
2169     4. Applied Giuseppe Maxia's patch to add additional features for controlling
2170        PCRE options from within the C++ wrapper.
2171    
2172     5. Named capturing subpatterns were not being correctly counted when a pattern
2173        was compiled. This caused two problems: (a) If there were more than 100
2174        such subpatterns, the calculation of the memory needed for the whole
2175        compiled pattern went wrong, leading to an overflow error. (b) Numerical
2176        back references of the form \12, where the number was greater than 9, were
2177        not recognized as back references, even though there were sufficient
2178        previous subpatterns.
2179    
2180     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
2181        versions of gcc, e.g. 2.95.4.
2182    
2183    
2184    Version 6.1 21-Jun-05
2185    ---------------------
2186    
2187     1. There was one reference to the variable "posix" in pcretest.c that was not
2188        surrounded by "#if !defined NOPOSIX".
2189    
2190     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
2191        the cross-check on the old pcre_info() function, for the benefit of the
2192        cut-down version of PCRE that is currently imported into Exim.
2193    
2194     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
2195        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
2196        patterns that start (?i) but I don't think that matters. The use of (?i) is
2197        just an example; this all applies to the other options as well.
2198    
2199     4. Since libtool seems to echo the compile commands it is issuing, the output
2200        from "make" can be reduced a bit by putting "@" in front of each libtool
2201        compile command.
2202    
2203     5. Patch from the folks at Google for configure.in to be a bit more thorough
2204        in checking for a suitable C++ installation before trying to compile the
2205        C++ stuff. This should fix a reported problem when a compiler was present,
2206        but no suitable headers.
2207    
2208     6. The man pages all had just "PCRE" as their title. I have changed them to
2209        be the relevant file name. I have also arranged that these names are
2210        retained in the file doc/pcre.txt, which is a concatenation in text format
2211        of all the man pages except the little individual ones for each function.
2212    
2213     7. The NON-UNIX-USE file had not been updated for the different set of source
2214        files that come with release 6. I also added a few comments about the C++
2215        wrapper.
2216    
2217    
2218    Version 6.0 07-Jun-05
2219    ---------------------
2220    
2221     1. Some minor internal re-organization to help with my DFA experiments.
2222    
2223     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
2224        didn't matter for the library itself when fully configured, but did matter
2225        when compiling without UCP support, or within Exim, where the ucp files are
2226        not imported.
2227    
2228     3. Refactoring of the library code to split up the various functions into
2229        different source modules. The addition of the new DFA matching code (see
2230        below) to a single monolithic source would have made it really too
2231        unwieldy, quite apart from causing all the code to be include in a
2232        statically linked application, when only some functions are used. This is
2233        relevant even without the DFA addition now that patterns can be compiled in
2234        one application and matched in another.
2235    
2236        The downside of splitting up is that there have to be some external
2237        functions and data tables that are used internally in different modules of
2238        the library but which are not part of the API. These have all had their
2239        names changed to start with "_pcre_" so that they are unlikely to clash
2240        with other external names.
2241    
2242     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
2243        a different (DFA) algorithm. Although it is slower than the original
2244        function, it does have some advantages for certain types of matching
2245        problem.
2246    
2247     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
2248        including restarting after a partial match.
2249    
2250     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
2251        defined when compiling for Windows was sent to me. I have put it into the
2252        code, though I have no means of testing or verifying it.
2253    
2254     7. Added the pcre_refcount() auxiliary function.
2255    
2256     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
2257        match before or at the first newline in the subject string. In pcretest,
2258        the /f option on a pattern can be used to set this.
2259    
2260     9. A repeated \w when used in UTF-8 mode with characters greater than 256
2261        would behave wrongly. This has been present in PCRE since release 4.0.
2262    
2263    10. A number of changes to the pcregrep command:
2264    
2265        (a) Refactored how -x works; insert ^(...)$ instead of setting
2266            PCRE_ANCHORED and checking the length, in preparation for adding
2267            something similar for -w.
2268    
2269        (b) Added the -w (match as a word) option.
2270    
2271        (c) Refactored the way lines are read and buffered so as to have more
2272            than one at a time available.
2273    
2274        (d) Implemented a pcregrep test script.
2275    
2276        (e) Added the -M (multiline match) option. This allows patterns to match
2277            over several lines of the subject. The buffering ensures that at least
2278            8K, or the rest of the document (whichever is the shorter) is available
2279            for matching (and similarly the previous 8K for lookbehind assertions).
2280    
2281        (f) Changed the --help output so that it now says
2282    
2283              -w, --word-regex(p)
2284    
2285            instead of two lines, one with "regex" and the other with "regexp"
2286            because that confused at least one person since the short forms are the
2287            same. (This required a bit of code, as the output is generated
2288            automatically from a table. It wasn't just a text change.)
2289    
2290        (g) -- can be used to terminate pcregrep options if the next thing isn't an
2291            option but starts with a hyphen. Could be a pattern or a path name
2292            starting with a hyphen, for instance.
2293    
2294        (h) "-" can be given as a file name to represent stdin.
2295    
2296        (i) When file names are being printed, "(standard input)" is used for
2297            the standard input, for compatibility with GNU grep. Previously
2298            "<stdin>" was used.
2299    
2300        (j) The option --label=xxx can be used to supply a name to be used for
2301            stdin when file names are being printed. There is no short form.
2302    
2303        (k) Re-factored the options decoding logic because we are going to add
2304            two more options that take data. Such options can now be given in four
2305            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
2306    
2307        (l) Added the -A, -B, and -C options for requesting that lines of context
2308            around matches be printed.
2309    
2310        (m) Added the -L option to print the names of files that do not contain
2311            any matching lines, that is, the complement of -l.
2312    
2313        (n) The return code is 2 if any file cannot be opened, but pcregrep does
2314            continue to scan other files.
2315    
2316        (o) The -s option was incorrectly implemented. For compatibility with other
2317            greps, it now suppresses the error message for a non-existent or non-
2318            accessible file (but not the return code). There is a new option called
2319            -q that suppresses the output of matching lines, which was what -s was
2320            previously doing.
2321    
2322        (p) Added --include and --exclude options to specify files for inclusion
2323            and exclusion when recursing.
2324    
2325    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
2326        Hopefully, it now does.
2327    
2328    12. Missing cast in pcre_study().
2329    
2330    13. Added an "uninstall" target to the makefile.
2331    
2332    14. Replaced "extern" in the function prototypes in Makefile.in with
2333        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
2334        world, but is set differently for Windows.
2335    
2336    15. Added a second compiling function called pcre_compile2(). The only
2337        difference is that it has an extra argument, which is a pointer to an
2338        integer error code. When there is a compile-time failure, this is set
2339        non-zero, in addition to the error test pointer being set to point to an
2340        error message. The new argument may be NULL if no error number is required
2341        (but then you may as well call pcre_compile(), which is now just a
2342        wrapper). This facility is provided because some applications need a
2343        numeric error indication, but it has also enabled me to tidy up the way
2344        compile-time errors are handled in the POSIX wrapper.
2345    
2346    16. Added VPATH=.libs to the makefile; this should help when building with one
2347        prefix path and installing with another. (Or so I'm told by someone who
2348        knows more about this stuff than I do.)
2349    
2350    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
2351        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
2352        match everything, including newlines. This is not POSIX-compatible, but
2353        somebody wanted the feature. From pcretest it can be activated by using
2354        both the P and the s flags.
2355    
2356    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
2357    
2358    19. libpcre.pc was being incorrectly installed as executable.
2359    
2360    20. A couple of places in pcretest check for end-of-line by looking for '\n';
2361        it now also looks for '\r' so that it will work unmodified on Windows.
2362    
2363    21. Added Google's contributed C++ wrapper to the distribution.
2364    
2365    22. Added some untidy missing memory free() calls in pcretest, to keep
2366        Electric Fence happy when testing.
2367    
2368    
2369    
2370    Version 5.0 13-Sep-04
2371    ---------------------
2372    
2373     1. Internal change: literal characters are no longer packed up into items
2374        containing multiple characters in a single byte-string. Each character
2375        is now matched using a separate opcode. However, there may be more than one
2376        byte in the character in UTF-8 mode.
2377    
2378     2. The pcre_callout_block structure has two new fields: pattern_position and
2379        next_item_length. These contain the offset in the pattern to the next match
2380        item, and its length, respectively.
2381    
2382     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
2383        insertion of callouts before each pattern item. Added the /C option to
2384        pcretest to make use of this.
2385    
2386     4. On the advice of a Windows user, the lines
2387    
2388          #if defined(_WIN32) || defined(WIN32)
2389          _setmode( _fileno( stdout ), 0x8000 );
2390          #endif  /* defined(_WIN32) || defined(WIN32) */
2391    
2392        have been added to the source of pcretest. This apparently does useful
2393        magic in relation to line terminators.
2394    
2395     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
2396        for the benefit of those environments where the "b" makes a difference.
2397    
2398     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
2399        to know about it. I have put a hack into configure.in that adds in code
2400        to set GCC=yes if CC=icc. This seems to end up at a point in the
2401        generated configure script that is early enough to affect the setting of
2402        compiler options, which is what is needed, but I have no means of testing
2403        whether it really works. (The user who reported this had patched the
2404        generated configure script, which of course I cannot do.)
2405    
2406        LATER: After change 22 below (new libtool files), the configure script
2407        seems to know about icc (and also ecc). Therefore, I have commented out
2408        this hack in configure.in.
2409    
2410     7. Added support for pkg-config (2 patches were sent in).
2411    
2412     8. Negated POSIX character classes that used a combination of internal tables
2413        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
2414        [[:^ascii]]. Typically, they would match almost any characters. The other
2415        POSIX classes were not broken in this way.
2416    
2417     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
2418        to find the match, as PCRE was deluded into thinking that the match had to
2419        start at the start point or following a newline. The same bug applied to
2420        patterns with negative forward assertions or any backward assertions
2421        preceding ".*" at the start, unless the pattern required a fixed first
2422        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
2423    
2424    10. In UTF-8 mode, when moving forwards in the subject after a failed match
2425        starting at the last subject character, bytes beyond the end of the subject
2426        string were read.
2427    
2428    11. Renamed the variable "class" as "classbits" to make life easier for C++
2429        users. (Previously there was a macro definition, but it apparently wasn't
2430        enough.)
2431    
2432    12. Added the new field "tables" to the extra data so that tables can be passed
2433        in at exec time, or the internal tables can be re-selected. This allows
2434        a compiled regex to be saved and re-used at a later time by a different
2435        program that might have everything at different addresses.
2436    
2437    13. Modified the pcre-config script so that, when run on Solaris, it shows a
2438        -R library as well as a -L library.
2439    
2440    14. The debugging options of pcretest (-d on the command line or D on a
2441        pattern) showed incorrect output for anything following an extended class
2442        that contained multibyte characters and which was followed by a quantifier.
2443    
2444    15. Added optional support for general category Unicode character properties
2445        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
2446        support. It adds about 90K to the size of the library. The meanings of the
2447        inbuilt class escapes such as \d and \s have NOT been changed.
2448    
2449    16. Updated pcredemo.c to include calls to free() to release the memory for the
2450        compiled pattern.
2451    
2452    17. The generated file chartables.c was being created in the source directory
2453        instead of in the building directory. This caused the build to fail if the
2454        source directory was different from the building directory, and was
2455        read-only.
2456    
2457    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
2458        file. No doubt somebody will tell me if they don't make sense... Also added
2459        Dan Mooney's comments about building on OpenVMS.
2460    
2461    19. Added support for partial matching via the PCRE_PARTIAL option for
2462        pcre_exec() and the \P data escape in pcretest.
2463    
2464    20. Extended pcretest with 3 new pattern features:
2465    
2466        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
2467              write the compiled pattern to the file whose name is "rest-of-line".
2468              This is a straight binary dump of the data, with the saved pointer to
2469              the character tables forced to be NULL. The study data, if any, is
2470              written too. After writing, pcretest reads a new pattern.
2471    
2472        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
2473              compiled pattern from the given file. There must not be any
2474              occurrences of "<" in the file name (pretty unlikely); if there are,
2475              pcretest will instead treat the initial "<" as a pattern delimiter.
2476              After reading in the pattern, pcretest goes on to read data lines as
2477              usual.
2478    
2479        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
2480              and 16-bit fields in a compiled pattern, to simulate a pattern that
2481              was compiled on a host of opposite endianness.
2482    
2483    21. The pcre-exec() function can now cope with patterns that were compiled on
2484        hosts of opposite endianness, with this restriction:
2485    
2486          As for any compiled expression that is saved and used later, the tables
2487          pointer field cannot be preserved; the extra_data field in the arguments
2488          to pcre_exec() should be used to pass in a tables address if a value
2489          other than the default internal tables were used at compile time.
2490    
2491    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
2492        now diagnosed as an error. Previously, most of the time, a negative number
2493        would have been treated as zero, but if in addition "ovector" was passed as
2494        NULL, a crash could occur.
2495    
2496    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
2497        new versions from the libtool 1.5 distribution (the last one is a copy of
2498        a file called libtool.m4). This seems to have fixed the need to patch
2499        "configure" to support Darwin 1.3 (which I used to do). However, I still
2500        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
2501        workstation).
2502    
2503    24. Changed the PCRE licence to be the more standard "BSD" licence.
2504    
2505    
2506    Version 4.5 01-Dec-03
2507    ---------------------
2508    
2509     1. There has been some re-arrangement of the code for the match() function so
2510        that it can be compiled in a version that does not call itself recursively.
2511        Instead, it keeps those local variables that need separate instances for
2512        each "recursion" in a frame on the heap, and gets/frees frames whenever it
2513        needs to "recurse". Keeping track of where control must go is done by means
2514        of setjmp/longjmp. The whole thing is implemented by a set of macros that
2515        hide most of the details from the main code, and operates only if
2516        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
2517        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
2518        operating.
2519    
2520        To make it easier for callers to provide specially tailored get/free
2521        functions for this usage, two new functions, pcre_stack_malloc, and
2522        pcre_stack_free, are used. They are always called in strict stacking order,
2523        and the size of block requested is always the same.
2524    
2525        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
2526        PCRE has been compiled to use the stack or the heap for recursion. The
2527        -C option of pcretest uses this to show which version is compiled.
2528    
2529        A new data escape \S, is added to pcretest; it causes the amounts of store
2530        obtained and freed by both kinds of malloc/free at match time to be added
2531        to the output.
2532    
2533     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
2534        what's available on my current Linux desktop machine.
2535    
2536     3. When matching a UTF-8 string, the test for a valid string at the start has
2537        been extended. If start_offset is not zero, PCRE now checks that it points
2538        to a byte that is the start of a UTF-8 character. If not, it returns
2539        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
2540        this is necessary because there may be backward assertions in the pattern.
2541        When matching the same subject several times, it may save resources to use
2542        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
2543    
2544     4. The code for checking the validity of UTF-8 strings has been tightened so
2545        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
2546        containing "overlong sequences".
2547    
2548     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
2549        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
2550        should have been "&", but it just so happened that all the cases this let
2551        through by mistake were picked up later in the function.
2552    
2553     6. I had used a variable called "isblank" - this is a C99 function, causing
2554        some compilers to warn. To avoid this, I renamed it (as "blankclass").
2555    
2556     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
2557        prompting; (b) run "./pcretest /dev/null" at the start of the test script
2558        so the version is shown; (c) stop "make test" echoing "./RunTest".
2559    
2560     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
2561    
2562     9. The prototype for memmove() for systems that don't have it was using
2563        size_t, but the inclusion of the header that defines size_t was later. I've
2564        moved the #includes for the C headers earlier to avoid this.
2565    
2566    10. Added some adjustments to the code to make it easier to compiler on certain
2567        special systems:
2568    
2569          (a) Some "const" qualifiers were missing.
2570          (b) Added the macro EXPORT before all exported functions; by default this
2571              is defined to be empty.
2572          (c) Changed the dftables auxiliary program (that builds chartables.c) so
2573              that it reads its output file name as an argument instead of writing
2574              to the standard output and assuming this can be redirected.
2575    
2576    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
2577        class containing characters with values greater than 255, PCRE compilation
2578        went into a loop.
2579    
2580    12. A recursive reference to a subpattern that was within another subpattern
2581        that had a minimum quantifier of zero caused PCRE to crash. For example,
2582        (x(y(?2))z)? provoked this bug with a subject that got as far as the
2583        recursion. If the recursively-called subpattern itself had a zero repeat,
2584        that was OK.
2585    
2586    13. In pcretest, the buffer for reading a data line was set at 30K, but the
2587        buffer into which it was copied (for escape processing) was still set at
2588        1024, so long lines caused crashes.
2589    
2590    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
2591        "internal error: code overflow...". This applied to any character class
2592        that was followed by a possessive quantifier.
2593    
2594    15. Modified the Makefile to add libpcre.la as a prerequisite for
2595        libpcreposix.la because I was told this is needed for a parallel build to
2596        work.
2597    
2598    16. If a pattern that contained .* following optional items at the start was
2599        studied, the wrong optimizing data was generated, leading to matching
2600        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
2601        matching string must start with a or b or c. The correct conclusion for
2602        this pattern is that a match can start with any character.
2603    
2604    
2605    Version 4.4 13-Aug-03
2606    ---------------------
2607    
2608     1. In UTF-8 mode, a character class containing characters with values between
2609        127 and 255 was not handled correctly if the compiled pattern was studied.
2610        In fixing this, I have also improved the studying algorithm for such
2611        classes (slightly).
2612    
2613     2. Three internal functions had redundant arguments passed to them. Removal
2614        might give a very teeny performance improvement.
2615    
2616     3. Documentation bug: the value of the capture_top field in a callout is *one
2617        more than* the number of the hightest numbered captured substring.
2618    
2619     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
2620        in incorrectly linking with a previously installed version. They now link
2621        explicitly with libpcre.la.
2622    
2623     5. configure.in no longer needs to recognize Cygwin specially.
2624    
2625     6. A problem in pcre.in for Windows platforms is fixed.
2626    
2627     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
2628        pcretest, it used to include the size of the study block as part of its
2629        output. Unfortunately, the structure contains a field that has a different
2630        size on different hardware architectures. This meant that the tests that
2631        showed this size failed. As the block is currently always of a fixed size,
2632        this information isn't actually particularly useful in pcretest output, so
2633        I have just removed it.
2634    
2635     8. Three pre-processor statements accidentally did not start in column 1.
2636        Sadly, there are *still* compilers around that complain, even though
2637        standard C has not required this for well over a decade. Sigh.
2638    
2639     9. In pcretest, the code for checking callouts passed small integers in the
2640        callout_data field, which is a void * field. However, some picky compilers
2641        complained about the casts involved for this on 64-bit systems. Now
2642        pcretest passes the address of the small integer instead, which should get
2643        rid of the warnings.
2644    
2645    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
2646        both compile and run time, and gives an error if an invalid UTF-8 sequence
2647        is found. There is a option for disabling this check in cases where the
2648        string is known to be correct and/or the maximum performance is wanted.
2649    
2650    11. In response to a bug report, I changed one line in Makefile.in from
2651    
2652            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
2653        to
2654            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
2655    
2656        to look similar to other lines, but I have no way of telling whether this
2657        is the right thing to do, as I do not use Windows. No doubt I'll get told
2658        if it's wrong...
2659    
2660    
2661    Version 4.3 21-May-03
2662    ---------------------
2663    
2664    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
2665       Makefile.
2666    
2667    2. Some refactoring to improve the quality of the code:
2668    
2669       (i)   The utf8_table... variables are now declared "const".
2670    
2671       (ii)  The code for \cx, which used the "case flipping" table to upper case
2672             lower case letters, now just substracts 32. This is ASCII-specific,
2673             but the whole concept of \cx is ASCII-specific, so it seems
2674             reasonable.
2675    
2676       (iii) PCRE was using its character types table to recognize decimal and
2677             hexadecimal digits in the pattern. This is silly, because it handles
2678             only 0-9, a-f, and A-F, but the character types table is locale-
2679             specific, which means strange things might happen. A private
2680             table is now used for this - though it costs 256 bytes, a table is
2681             much faster than multiple explicit tests. Of course, the standard
2682             character types table is still used for matching digits in subject
2683             strings against \d.
2684    
2685       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
2686             ending in _t are). So I've renamed it as ESC_tee.
2687    
2688    3. The first argument for regexec() in the POSIX wrapper should have been
2689       defined as "const".
2690    
2691    4. Changed pcretest to use malloc() for its buffers so that they can be
2692       Electric Fenced for debugging.
2693    
2694    5. There were several places in the code where, in UTF-8 mode, PCRE would try
2695       to read one or more bytes before the start of the subject string. Often this
2696       had no effect on PCRE's behaviour, but in some circumstances it could
2697       provoke a segmentation fault.
2698    
2699    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
2700       to try to read one or more bytes before the start of the subject string.
2701    
2702    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
2703       UTF-8 support could misbehave in various ways if the subject string
2704       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
2705       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
2706       back over UTF-8 characters.)
2707    
2708    
2709    Version 4.2 14-Apr-03
2710    ---------------------
2711    
2712    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
2713    
2714    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
2715         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
2716         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
2717         [WIN_PREFIX]: new variable, "cyg" for Cygwin
2718         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
2719           and BUILD_EXEEXT
2720         Note: automatic setting of the BUILD variables is not yet working
2721         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
2722           compile-time but not at link-time
2723         [LINK]: use for linking executables only
2724         make different versions for Windows and non-Windows
2725         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
2726           libraries
2727         [LINK_FOR_BUILD]: new variable
2728         [OBJEXT]: use throughout
2729         [EXEEXT]: use throughout
2730         <winshared>: new target
2731         <wininstall>: new target
2732         <dftables.o>: use native compiler
2733         <dftables>: use native linker
2734         <install>: handle Windows platform correctly
2735         <clean>: ditto
2736         <check>: ditto
2737         copy DLL to top builddir before testing
2738    
2739       As part of these changes, -no-undefined was removed again. This was reported
2740       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
2741       in any case.
2742    
2743    3. Some tidies to get rid of compiler warnings:
2744    
2745       . In the match_data structure, match_limit was an unsigned long int, whereas
2746         match_call_count was an int. I've made them both unsigned long ints.
2747    
2748       . In pcretest the fact that a const uschar * doesn't automatically cast to
2749         a void * provoked a warning.
2750    
2751       . Turning on some more compiler warnings threw up some "shadow" variables
2752         and a few more missing casts.
2753    
2754    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
2755       option, a class that contained a single character with a value between 128
2756       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
2757    
2758    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
2759       option, a class that contained several characters, but with at least one
2760       whose value was between 128 and 255 caused PCRE to crash.
2761    
2762    
2763    Version 4.1 12-Mar-03
2764    ---------------------
2765    
2766    1. Compiling with gcc -pedantic found a couple of places where casts were
2767    needed, and a string in dftables.c that was longer than standard compilers are
2768    required to support.
2769    
2770    2. Compiling with Sun's compiler found a few more places where the code could
2771    be tidied up in order to avoid warnings.
2772    
2773    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
2774    first of these names is deprecated in the latest Autoconf in favour of the name
2775    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
2776    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
2777    analogy I have changed it to CFLAGS_FOR_BUILD.
2778    
2779    4. Added -no-undefined to the linking command in the Makefile, because this is
2780    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2781    linking step for the pcreposix library.
2782    
2783    5. PCRE was failing to diagnose the case of two named groups with the same
2784    name.
2785    
2786    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2787    literal character that is needed in the subject for a match, and scans along to
2788    ensure that it is present before embarking on the full matching process. This
2789    saves time in cases of nested unlimited repeats that are never going to match.
2790    Problem: the scan can take a lot of time if the subject is very long (e.g.
2791    megabytes), thus penalizing straightforward matches. It is now done only if the
2792    amount of subject to be scanned is less than 1000 bytes.
2793    
2794    7. A lesser problem with the same optimization is that it was recording the
2795    first character of an anchored pattern as "needed", thus provoking a search
2796    right along the subject, even when the first match of the pattern was going to
2797    fail. The "needed" character is now not set for anchored patterns, unless it
2798    follows something in the pattern that is of non-fixed length. Thus, it still
2799    fulfils its original purpose of finding quick non-matches in cases of nested
2800    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2801    
2802    
2803    Version 4.0 17-Feb-03
2804    ---------------------
2805    
2806    1. If a comment in an extended regex that started immediately after a meta-item
2807    extended to the end of string, PCRE compiled incorrect data. This could lead to
2808    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2809    
2810    2. Moved to autoconf 2.53 and libtool 1.4.2.
2811    
2812    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2813    the special perltest8 script is no longer needed - all the tests can be run
2814    from a single perltest script.
2815    
2816    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2817    by \s. It has now been removed in PCRE. This means it isn't recognized as
2818    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2819    class [:space:] *does* include VT, thereby creating a mess.
2820    
2821    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2822    space and tab.
2823    
2824    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2825    its new features into the main test script, reducing the number of scripts.
2826    
2827    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2828    were backward compatible, and made the (?i) apply to the whole pattern, as if
2829    /i were given. Now it behaves more logically, and applies the option setting
2830    only to what follows. PCRE has been changed to follow suit. However, if it
2831    finds options settings right at the start of the pattern, it extracts them into
2832    the global options, as before. Thus, they show up in the info data.
2833    
2834    8. Added support for the \Q...\E escape sequence. Characters in between are
2835    treated as literals. This is slightly different from Perl in that $ and @ are
2836    also handled as literals inside the quotes. In Perl, they will cause variable
2837    interpolation. Note the following examples:
2838    
2839        Pattern            PCRE matches      Perl matches
2840    
2841        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2842        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2843        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2844    
2845    For compatibility with Perl, \Q...\E sequences are recognized inside character
2846    classes as well as outside them.
2847    
2848    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2849    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2850    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2851    signed/unsigned warnings.
2852    
2853    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2854    option for pcretest, so I've replaced it by a simple function that does just
2855    that job.
2856    
2857    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2858    "pcregrep -".
2859    
2860    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2861    Java package. This provides some syntactic sugar for simple cases of what my
2862    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2863    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2864    item, you can use this simplified notation. Note that only makes sense with
2865    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2866    greediness, whatever the setting of the PCRE_UNGREEDY option.
2867    
2868    13. A change of greediness default within a pattern was not taking effect at
2869    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2870    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2871    was abstracted outside.
2872    
2873    14. PCRE now supports the \G assertion. It is true when the current matching
2874    position is at the start point of the match. This differs from \A when the
2875    starting offset is non-zero. Used with the /g option of pcretest (or similar
2876    code), it works in the same way as it does for Perl's /g option. If all
2877    alternatives of a regex begin with \G, the expression is anchored to the start
2878    match position, and the "anchored" flag is set in the compiled expression.
2879    
2880    15. Some bugs concerning the handling of certain option changes within patterns
2881    have been fixed. These applied to options other than (?ims). For example,
2882    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2883    been the other way round. Some of this was related to change 7 above.
2884    
2885    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2886    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2887    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2888    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2889    
2890    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2891    mode. Unlike ".", it always matches newline, whatever the setting of
2892    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2893    assertions. Perl allows it, but it doesn't (in general) work because it can't
2894    calculate the length of the lookbehind. At least, that's the case for Perl
2895    5.8.0 - I've been told they are going to document that it doesn't work in
2896    future.
2897    
2898    18. Added an error diagnosis for escapes that PCRE does not support: these are
2899    \L, \l, \N, \P, \p, \U, \u, and \X.
2900    
2901    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2902    reading past the end of the pattern in cases such as /[abcd/.
2903    
2904    20. PCRE was getting more memory than necessary for patterns with classes that
2905    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2906    
2907    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2908    compiling PCRE for use with Virtual Pascal.
2909    
2910    22. Small fix to the Makefile to make it work properly if the build is done
2911    outside the source tree.
2912    
2913    23. Added a new extension: a condition to go with recursion. If a conditional
2914    subpattern starts with (?(R) the "true" branch is used if recursion has
2915    happened, whereas the "false" branch is used only at the top level.
2916    
2917    24. When there was a very long string of literal characters (over 255 bytes
2918    without UTF support, over 250 bytes with UTF support), the computation of how
2919    much memory was required could be incorrect, leading to segfaults or other
2920    strange effects.
2921    
2922    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2923    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2924    there was a subsequent back reference to those brackets. This meant that, for
2925    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2926    possible to check for precisely this case. All we can do is abandon the
2927    optimization if .* occurs inside capturing brackets when there are any back
2928    references whatsoever. (See below for a better fix that came later.)
2929    
2930    26. The handling of the optimization for finding the first character of a
2931    non-anchored pattern, and for finding a character that is required later in the
2932    match were failing in some cases. This didn't break the matching; it just
2933    failed to optimize when it could. The way this is done has been re-implemented.
2934    
2935    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2936    
2937    28. Added a new feature that provides some of the functionality that Perl
2938    provides with (?{...}). The facility is termed a "callout". The way it is done
2939    in PCRE is for the caller to provide an optional function, by setting
2940    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2941    global variable. By default it is unset, which disables all calling out. To get
2942    the function called, the regex must include (?C) at appropriate points. This
2943    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2944    This provides a means of identifying different callout points. When PCRE
2945    reaches such a point in the regex, if pcre_callout has been set, the external
2946    function is called. It is provided with data in a structure called
2947    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2948    matching continues; if it returns a non-zero value, the match at the current
2949    point fails. However, backtracking will occur if possible. [This was changed
2950    later and other features added - see item 49 below.]
2951    
2952    29. pcretest is upgraded to test the callout functionality. It provides a
2953    callout function that displays information. By default, it shows the start of
2954    the match and the current position in the text. There are some new data escapes
2955    to vary what happens:
2956    
2957        \C+         in addition, show current contents of captured substrings
2958        \C-         do not supply a callout function
2959        \C!n        return 1 when callout number n is reached
2960        \C!n!m      return 1 when callout number n is reached for the mth time
2961    
2962    30. If pcregrep was called with the -l option and just a single file name, it
2963    output "<stdin>" if a match was found, instead of the file name.
2964    
2965    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2966    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2967    pcre_exec(). This saves a malloc/free per call. The default value of
2968    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2969    when configuring.
2970    
2971    32. The default maximum size of a compiled pattern is 64K. There have been a
2972    few cases of people hitting this limit. The code now uses macros to handle the
2973    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2974    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2975    configuring. Tests 2 and 5 work only with 2-byte links because they output
2976    debugging information about compiled patterns.
2977    
2978    33. Internal code re-arrangements:
2979    
2980    (a) Moved the debugging function for printing out a compiled regex into
2981        its own source file (printint.c) and used #include to pull it into
2982        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2983        separate copies.
2984    
2985    (b) Defined the list of op-code names for debugging as a macro in
2986        internal.h so that it is next to the definition of the opcodes.
2987    
2988    (c) Defined a table of op-code lengths for simpler skipping along compiled
2989        code. This is again a macro in internal.h so that it is next to the
2990        definition of the opcodes.
2991    
2992    34. Added support for recursive calls to individual subpatterns, along the
2993    lines of Robin Houston's patch (but implemented somewhat differently).
2994    
2995    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2996    allow it to read and process whole directories in Win32. This code was
2997    contributed by Lionel Fourquaux; it has not been tested by me.
2998    
2999    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
3000    used to name a group. Names consist of alphanumerics and underscores, and must
3001    be unique. Back references use the syntax (?P=name) and recursive calls use
3002    (?P>name) which is a PCRE extension to the Python extension. Groups still have
3003    numbers. The function pcre_fullinfo() can be used after compilation to extract
3004    a name/number map. There are three relevant calls:
3005    
3006      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
3007      PCRE_INFO_NAMECOUNT            yields the number of entries
3008      PCRE_INFO_NAMETABLE            yields a pointer to the map.
3009    
3010    The map is a vector of fixed-size entries. The size of each entry depends on
3011    the length of the longest name used. The first two bytes of each entry are the
3012    group number, most significant byte first. There follows the corresponding
3013    name, zero terminated. The names are in alphabetical order.
3014    
3015    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
3016    case instead of 255. Making it the same both with and without UTF-8 support
3017    means that the same test output works with both.
3018    
3019    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
3020    calling malloc() with a zero argument.
3021    
3022    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
3023    optimization. I've improved things by keeping a bitmap of backreferences with
3024    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
3025    fact referenced, the optimization can be applied. It is unlikely that a
3026    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
3027    the match to follow \n) will appear inside brackets with a number greater than
3028    31, but if it does, any back reference > 31 suppresses the optimization.
3029    
3030    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
3031    of disabling numbered capturing parentheses. Any opening parenthesis that is
3032    not followed by ? behaves as if it were followed by ?: but named parentheses
3033    can still be used for capturing (and they will acquire numbers in the usual
3034    way).
3035    
3036    41. Redesigned the return codes from the match() function into yes/no/error so
3037    that errors can be passed back from deep inside the nested calls. A malloc
3038    failure while inside a recursive subpattern call now causes the
3039    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
3040    
3041    42. It is now possible to set a limit on the number of times the match()
3042    function is called in a call to pcre_exec(). This facility makes it possible to
3043    limit the amount of recursion and backtracking, though not in a directly
3044    obvious way, because the match() function is used in a number of different
3045    circumstances. The count starts from zero for each position in the subject
3046    string (for non-anchored patterns). The default limit is, for compatibility, a
3047    large number, namely 10 000 000. You can change this in two ways:
3048    
3049    (a) When configuring PCRE before making, you can use --with-match-limit=n
3050        to set a default value for the compiled library.
3051    
3052    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
3053        a different value is set. See 45 below.
3054    
3055    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
3056    
3057    43. Added a new function pcre_config(int, void *) to enable run-time extraction
3058    of things that can be changed at compile time. The first argument specifies
3059    what is wanted and the second points to where the information is to be placed.
3060    The current list of available information is:
3061    
3062      PCRE_CONFIG_UTF8
3063    
3064    The output is an integer that is set to one if UTF-8 support is available;
3065    otherwise it is set to zero.
3066    
3067      PCRE_CONFIG_NEWLINE
3068    
3069    The output is an integer that it set to the value of the code that is used for
3070    newline. It is either LF (10) or CR (13).
3071    
3072      PCRE_CONFIG_LINK_SIZE
3073    
3074    The output is an integer that contains the number of bytes used for internal
3075    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
3076    
3077      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
3078    
3079    The output is an integer that contains the threshold above which the POSIX
3080    interface uses malloc() for output vectors. See item 31 above.
3081    
3082      PCRE_CONFIG_MATCH_LIMIT
3083    
3084    The output is an unsigned integer that contains the default limit of the number
3085    of match() calls in a pcre_exec() execution. See 42 above.
3086    
3087    44. pcretest has been upgraded by the addition of the -C option. This causes it
3088    to extract all the available output from the new pcre_config() function, and to
3089    output it. The program then exits immediately.
3090    
3091    45. A need has arisen to pass over additional data with calls to pcre_exec() in
3092    order to support additional features. One way would have been to define
3093    pcre_exec2() (for example) with extra arguments, but this would not have been
3094    extensible, and would also have required all calls to the original function to
3095    be mapped to the new one. Instead, I have chosen to extend the mechanism that
3096    is used for passing in "extra" data from pcre_study().
3097    
3098    The pcre_extra structure is now exposed and defined in pcre.h. It currently
3099    contains the following fields:
3100    
3101      flags         a bitmap indicating which of the following fields are set
3102      study_data    opaque data from pcre_study()
3103      match_limit   a way of specifying a limit on match() calls for a specific
3104                      call to pcre_exec()
3105      callout_data  data for callouts (see 49 below)
3106    
3107    The flag bits are also defined in pcre.h, and are
3108    
3109      PCRE_EXTRA_STUDY_DATA
3110      PCRE_EXTRA_MATCH_LIMIT
3111      PCRE_EXTRA_CALLOUT_DATA
3112    
3113    The pcre_study() function now returns one of these new pcre_extra blocks, with
3114    the actual study data pointed to by the study_data field, and the
3115    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
3116    before. That is, this change is entirely upwards-compatible and requires no
3117    change to existing code.
3118    
3119    If you want to pass in additional data to pcre_exec(), you can either place it
3120    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
3121    block.
3122    
3123    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
3124    data string contains the escape sequence \M, pcretest calls pcre_exec() several
3125    times with different match limits, until it finds the minimum value needed for
3126    pcre_exec() to complete. The value is then output. This can be instructive; for
3127    most simple matches the number is quite small, but for pathological cases it
3128    gets very large very quickly.
3129    
3130    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
3131    returns the size of the data block pointed to by the study_data field in a
3132    pcre_extra block, that is, the value that was passed as the argument to
3133    pcre_malloc() when PCRE was getting memory in which to place the information
3134    created by pcre_study(). The fourth argument should point to a size_t variable.
3135    pcretest has been extended so that this information is shown after a successful
3136    pcre_study() call when information about the compiled regex is being displayed.
3137    
3138    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
3139    because what follows is always an absolute path. (Later: it turns out that this
3140    is more than cosmetic for MinGW, because it doesn't like empty path
3141    components.)
3142    
3143    49. Some changes have been made to the callout feature (see 28 above):
3144    
3145    (i)  A callout function now has three choices for what it returns:
3146    
3147           0  =>  success, carry on matching
3148         > 0  =>  failure at this point, but backtrack if possible
3149         < 0  =>  serious error, return this value from pcre_exec()
3150    
3151         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
3152         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
3153         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
3154         use by callout functions. It will never be used by PCRE itself.
3155    
3156    (ii) The pcre_extra structure (see 45 above) has a void * field called
3157         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
3158         pcre_callout_block structure has a field of the same name. The contents of
3159         the field passed in the pcre_extra structure are passed to the callout
3160         function in the corresponding field in the callout block. This makes it
3161         easier to use the same callout-containing regex from multiple threads. For
3162         testing, the pcretest program has a new data escape
3163    
3164           \C*n        pass the number n (may be negative) as callout_data
3165    
3166         If the callout function in pcretest receives a non-zero value as
3167         callout_data, it returns that value.
3168    
3169    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
3170    there were some redundant $(CFLAGS) in commands that are now specified as
3171    $(LINK), which already includes $(CFLAGS).
3172    
3173    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
3174    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
3175    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
3176    one-byte characters throughout. Note that case-insensitive matching applies
3177    only to characters whose values are less than 256. PCRE doesn't support the
3178    notion of cases for higher-valued characters.
3179    
3180    (i)   A character class whose characters are all within 0-255 is handled as
3181          a bit map, and the map is inverted for negative classes. Previously, a
3182          character > 255 always failed to match such a class; however it should
3183          match if the class was a negative one (e.g. [^ab]). This has been fixed.
3184    
3185    (ii)  A negated character class with a single character < 255 is coded as
3186          "not this character" (OP_NOT). This wasn't working properly when the test
3187          character was multibyte, either singly or repeated.
3188    
3189    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
3190          mode, for example: \x{100}{2,3}.
3191    
3192    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
3193          singly or repeated) now correctly test multibyte characters. However,
3194          PCRE doesn't recognize any characters with values greater than 255 as
3195          digits, spaces, or word characters. Such characters always match \D, \S,
3196          and \W, and never match \d, \s, or \w.
3197    
3198    (v)   Classes may now contain characters and character ranges with values
3199          greater than 255. For example: [ab\x{100}-\x{400}].
3200    
3201    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
3202          PCRE in UTF-8 mode.
3203    
3204    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
3205    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
3206    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
3207    value.)
3208    
3209    53. The single man page has become too large. I have therefore split it up into
3210    a number of separate man pages. These also give rise to individual HTML pages;
3211    these are now put in a separate directory, and there is an index.html page that
3212    lists them all. Some hyperlinking between the pages has been installed.
3213    
3214    54. Added convenience functions for handling named capturing parentheses.
3215    
3216    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
3217    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
3218    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
3219    are faulted.
3220    
3221    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
3222    calling configure. These values are used when compiling the dftables.c program
3223    which is run to generate the source of the default character tables. They
3224    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
3225    you will need to set these values.
3226    
3227    57. Updated the building process for Windows DLL, as provided by Fred Cox.
3228    
3229    
3230    Version 3.9 02-Jan-02
3231    ---------------------
3232    
3233    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
3234    
3235    2. If --disable-static was given, the building process failed when trying to
3236    build pcretest and pcregrep. (For some reason it was using libtool to compile
3237    them, which is not right, as they aren't part of the library.)
3238    
3239    
3240    Version 3.8 18-Dec-01
3241    ---------------------
3242    
3243    1. The experimental UTF-8 code was completely screwed up. It was packing the
3244    bytes in the wrong order. How dumb can you get?
3245    
3246    
3247    Version 3.7 29-Oct-01
3248    ---------------------
3249    
3250    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
3251    This caused pcretest, when used on the test data, to segfault. Unfortunately,
3252    this didn't happen under Solaris 8, where I normally test things.
3253    
3254    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
3255    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
3256    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
3257    this fix an hour or so after the initial 3.7 release.)
3258    
3259    
3260    Version 3.6 23-Oct-01
3261    ---------------------
3262    
3263    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
3264    offsets passed as NULL with zero offset count.
3265    
3266    2. The config.guess and config.sub files had not been updated when I moved to
3267    the latest autoconf.
3268    
3269    
3270    Version 3.5 15-Aug-01
3271    ---------------------
3272    
3273    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
3274    had been forgotten.
3275    
3276    2. By using declared but undefined structures, we can avoid using "void"
3277    definitions in pcre.h while keeping the internal definitions of the structures
3278    private.
3279    
3280    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
3281    user point of view, this means that both static and shared libraries are built
3282    by default, but this can be individually controlled. More of the work of
3283    handling this static/shared cases is now inside libtool instead of PCRE's make
3284    file.
3285    
3286    4. The pcretest utility is now installed along with pcregrep because it is
3287    useful for users (to test regexs) and by doing this, it automatically gets
3288    relinked by libtool. The documentation has been turned into a man page, so
3289    there are now .1, .txt, and .html versions in /doc.
3290    
3291    5. Upgrades to pcregrep:
3292       (i)   Added long-form option names like gnu grep.
3293       (ii)  Added --help to list all options with an explanatory phrase.
3294       (iii) Added -r, --recursive to recurse into sub-directories.
3295       (iv)  Added -f, --file to read patterns from a file.
3296    
3297    6. pcre_exec() was referring to its "code" argument before testing that
3298    argument for NULL (and giving an error if it was NULL).
3299    
3300    7. Upgraded Makefile.in to allow for compiling in a different directory from
3301    the source directory.
3302    
3303    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
3304    options bits, the pointer it was passed was to an int instead of to an unsigned
3305    long int. This mattered only on 64-bit systems.
3306    
3307    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
3308    generated) instead of pcre.in, which it its source. Also made the same change
3309    in several of the .c files.
3310    
3311    10. A new release of gcc defines printf() as a macro, which broke pcretest
3312    because it had an ifdef in the middle of a string argument for printf(). Fixed
3313    by using separate calls to printf().
3314    
3315    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
3316    script, to force use of CR or LF instead of \n in the source. On non-Unix
3317    systems, the value can be set in config.h.
3318    
3319    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
3320    absolute limit. Changed the text of the error message to make this clear, and
3321    likewise updated the man page.
3322    
3323    13. The limit of 99 on the number of capturing subpatterns has been removed.
3324    The new limit is 65535, which I hope will not be a "real" limit.
3325    
3326    
3327    Version 3.4 22-Aug-00
3328    ---------------------
3329    
3330    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
3331    
3332    2. Diagnose condition (?(0) as an error instead of crashing on matching.
3333    
3334    
3335    Version 3.3 01-Aug-00
3336    ---------------------
3337    
3338    1. If an octal character was given, but the value was greater than \377, it
3339    was not getting masked to the least significant bits, as documented. This could
3340    lead to crashes in some systems.
3341    
3342    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
3343    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
3344    
3345    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
3346    These just pass their arguments on to (pcre_free)(), but they are provided
3347    because some uses of PCRE bind it to non-C systems that can call its functions,
3348    but cannot call free() or pcre_free() directly.
3349    
3350    4. Add "make test" as a synonym for "make check". Corrected some comments in
3351    the Makefile.
3352    
3353    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
3354    Makefile.
3355    
3356    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
3357    command called pgrep for grepping around the active processes.
3358    
3359    7. Added the beginnings of support for UTF-8 character strings.
3360    
3361    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
3362    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
3363    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
3364    out for the ar command.)
3365    
3366    
3367    Version 3.2 12-May-00
3368    ---------------------
3369    
3370    This is purely a bug fixing release.
3371    
3372    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
3373    of ZA. This was just one example of several cases that could provoke this bug,
3374    which was introduced by change 9 of version 2.00. The code for breaking
3375    infinite loops after an iteration that matches an empty string was't working
3376    correctly.
3377    
3378    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
3379    when matched against abbab (for example). After matching an empty string, it
3380    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
3381    caused it to match further down the string than it should.
3382    
3383    3. The code contained an inclusion of sys/types.h. It isn't clear why this
3384    was there because it doesn't seem to be needed, and it causes trouble on some
3385    systems, as it is not a Standard C header. It has been removed.
3386    
3387    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
3388    were reported on the Macintosh. The changes were from
3389    
3390      while ((c = *(++ptr)) != 0 && c != '\n');
3391    to
3392      while ((c = *(++ptr)) != 0 && c != '\n') ;
3393    
3394    Totally extraordinary, but if that's what it takes...
3395    
3396    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
3397    available. Added HAVE_BCOPY and an autoconf test for it; if neither
3398    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
3399    assumes the way PCRE uses memmove() (always moving upwards).
3400    
3401    6. PCRE is being used in one environment where strchr() is not available. There
3402    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
3403    faster code anyway.
3404    
3405    
3406    Version 3.1 09-Feb-00
3407    ---------------------
3408    
3409    The only change in this release is the fixing of some bugs in Makefile.in for
3410    the "install" target:
3411    
3412    (1) It was failing to install pcreposix.h.
3413    
3414    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
3415    
3416    
3417    Version 3.0 01-Feb-00
3418    ---------------------
3419    
3420    1. Add support for the /+ modifier to perltest (to output $` like it does in
3421    pcretest).
3422    
3423    2. Add support for the /g modifier to perltest.
3424    
3425    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
3426    matches null strings.
3427    
3428    4. Fix perltest so that it doesn't do unwanted things when fed an empty
3429    pattern. Perl treats empty patterns specially - it reuses the most recent
3430    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
3431    effect.
3432    
3433    5. The POSIX interface was broken in that it was just handing over the POSIX
3434    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
3435    required a bigger vector, with some working space on the end. This means that
3436    the POSIX wrapper now has to get and free some memory, and copy the results.
3437    
3438    6. Added some simple autoconf support, placing the test data and the
3439    documentation in separate directories, re-organizing some of the
3440    information files, and making it build pcre-config (a GNU standard). Also added
3441    libtool support for building PCRE as a shared library, which is now the
3442    default.
3443    
3444    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
3445    09 are not valid octal constants. Single digits will be used for minor values
3446    less than 10.
3447    
3448    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
3449    existing programs that set these in the POSIX interface can use PCRE without
3450    modification.
3451    
3452    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
3453    return all that pcre_info() returns, plus additional data. The pcre_info()
3454    function is retained for compatibility, but is considered to be obsolete.
3455    
3456    10. Added experimental recursion feature (?R) to handle one common case that
3457    Perl 5.6 will be able to do with (?p{...}).
3458    
3459    11. Added support for POSIX character classes like [:alpha:], which Perl is
3460    adopting.
3461    
3462    
3463    Version 2.08 31-Aug-99
3464    ----------------------
3465    
3466    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
3467    trying to match at the startoffset position, but instead was moving forward to
3468    the next newline as if a previous match had failed.
3469    
3470    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
3471    and could get into a loop if a null string was matched other than at the start
3472    of the subject.
3473    
3474    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
3475    be distinguished at compile time, and for completeness also added PCRE_DATE.
3476    
3477    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
3478    in GnuWin32 environments.
3479    
3480    
3481    Version 2.07 29-Jul-99
3482    ----------------------
3483    
3484    1. The documentation is now supplied in plain text form and HTML as well as in
3485    the form of man page sources.
3486    
3487    2. C++ compilers don't like assigning (void *) values to other pointer types.
3488    In particular this affects malloc(). Although there is no problem in Standard
3489    C, I've put in casts to keep C++ compilers happy.
3490    
3491    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
3492    should be (const char *).
3493    
3494    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
3495    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
3496    However, I haven't made this a standard facility. The documentation doesn't
3497    mention it, and the Makefile doesn't support it.
3498    
3499    5. The Makefile now contains an "install" target, with editable destinations at
3500    the top of the file. The pcretest program is not installed.
3501    
3502    6. pgrep -V now gives the PCRE version number and date.
3503    
3504    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
3505    causing the entire string to be ignored, instead of just the last character.
3506    
3507    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
3508    non-matching string, it can take a very, very long time, even for strings of
3509    quite modest length, because of the nested recursion. PCRE now does better in
3510    some of these cases. It does this by remembering the last required literal
3511    character in the pattern, and pre-searching the subject to ensure it is present
3512    before running the real match. In other words, it applies a heuristic to detect
3513    some types of certain failure quickly, and in the above example, if presented
3514    with a string that has no trailing " it gives "no match" very quickly.
3515    
3516    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
3517    other alternatives are tried instead.
3518    
3519    
3520    Version 2.06 09-Jun-99
3521    ----------------------
3522    
3523    1. Change pcretest's output for amount of store used to show just the code
3524    space, because the remainder (the data block) varies in size between 32-bit and
3525    64-bit systems.
3526    
3527    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
3528    start matching at. This allows lookbehinds to work when searching for multiple
3529    occurrences in a string.
3530    
3531    3. Added additional options to pcretest for testing multiple occurrences:
3532    
3533       /+   outputs the rest of the string that follows a match
3534       /g   loops for multiple occurrences, using the new startoffset argument
3535       /G   loops for multiple occurrences by passing an incremented pointer
3536    
3537    4. PCRE wasn't doing the "first character" optimization for patterns starting
3538    with \b or \B, though it was doing it for other lookbehind assertions. That is,
3539    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
3540    the letter 'x'. On long subject strings, this gives a significant speed-up.
3541    
3542    
3543    Version 2.05 21-Apr-99
3544    ----------------------
3545    
3546    1. Changed the type of magic_number from int to long int so that it works
3547    properly on 16-bit systems.
3548    
3549    2. Fixed a bug which caused patterns starting with .* not to work correctly
3550    when the subject string contained newline characters. PCRE was assuming
3551    anchoring for such patterns in all cases, which is not correct because .* will
3552    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
3553    DOTALL is set at top level; otherwise it knows that patterns starting with .*
3554    must be retried after every newline in the subject.
3555    
3556    
3557    Version 2.04 18-Feb-99
3558    ----------------------
3559    
3560    1. For parenthesized subpatterns with repeats whose minimum was zero, the
3561    computation of the store needed to hold the pattern was incorrect (too large).
3562    If such patterns were nested a few deep, this could multiply and become a real
3563    problem.
3564    
3565    2. Added /M option to pcretest to show the memory requirement of a specific
3566    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
3567    
3568    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
3569    compiled in such a way that the backtracking after subsequent failure was
3570    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
3571    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
3572    
3573    
3574    Version 2.03 02-Feb-99
3575    ----------------------
3576    
3577    1. Fixed typo and small mistake in man page.
3578    
3579    2. Added 4th condition (GPL supersedes if conflict) and created separate
3580    LICENCE file containing the conditions.
3581    
3582    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
3583    Perl, that is the internal \ allows the delimiter to be included in the
3584    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
3585    the final delimiter, add \ to the end of the pattern (to test the error).
3586    
3587    4. Added the convenience functions for extracting substrings after a successful
3588    match. Updated pcretest to make it able to test these functions.
3589    
3590    
3591    Version 2.02 14-Jan-99
3592    ----------------------
3593    
3594    1. Initialized the working variables associated with each extraction so that
3595    their saving and restoring doesn't refer to uninitialized store.
3596    
3597    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
3598    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
3599    fix the problem.
3600    
3601    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
3602    calls, and wasn't printing the correct value for compiling calls. Increased the
3603    default value of LOOPREPEAT, and the number of significant figures in the
3604    times.
3605    
3606    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
3607    
3608    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
3609    a building problem on Windows NT with a FAT file system.
3610    
3611    
3612    Version 2.01 21-Oct-98
3613    ----------------------
3614    
3615    1. Changed the API for pcre_compile() to allow for the provision of a pointer
3616    to character tables built by pcre_maketables() in the current locale. If NULL
3617    is passed, the default tables are used.
3618    
3619    
3620    Version 2.00 24-Sep-98
3621    ----------------------
3622    
3623    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
3624    it any more.
3625    
3626    2. Allow quantification of (?>) groups, and make it work correctly.
3627    
3628    3. The first character computation wasn't working for (?>) groups.
3629    
3630    4. Correct the implementation of \Z (it is permitted to match on the \n at the
3631    end of the subject) and add 5.005's \z, which really does match only at the
3632    very end of the subject.
3633    
3634    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
3635    
3636    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
3637    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
3638    localized options. All options to pcre_study() were also removed.
3639    
3640    7. Add other new features from 5.005:
3641    
3642       $(?<=           positive lookbehind
3643       $(?<!           negative lookbehind
3644       (?imsx-imsx)    added the unsetting capability
3645                       such a setting is global if at outer level; local otherwise
3646       (?imsx-imsx:)   non-capturing groups with option setting
3647       (?(cond)re|re)  conditional pattern matching
3648    
3649       A backreference to itself in a repeated group matches the previous
3650       captured string.
3651    
3652    8. General tidying up of studying (both automatic and via "study")
3653    consequential on the addition of new assertions.
3654    
3655    9. As in 5.005, unlimited repeated groups that could match an empty substring
3656    are no longer faulted at compile time. Instead, the loop is forcibly broken at
3657    runtime if any iteration does actually match an empty substring.
3658    
3659    10. Include the RunTest script in the distribution.
3660    
3661    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
3662    discrepancies, some of which were old and were also with respect to 5.004. They
3663    have now been fixed.
3664    
3665    
3666    Version 1.09 28-Apr-98
3667    ----------------------
3668    
3669    1. A negated single character class followed by a quantifier with a minimum
3670    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
3671    program crashes, or just wrong answers. This did not apply to negated classes
3672    containing more than one character, or to minima other than one.
3673    
3674    
3675  Version 1.08 27-Mar-98  Version 1.08 27-Mar-98
3676  ----------------------  ----------------------

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