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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 7.6 19-Jan-08  Version 8.11 10-Oct-2010
5    ------------------------
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".
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).
20    3.  If \s appeared in a character class, it removed the VT character from
21        the class, even if it had been included by some previous item, for example
22        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
23        of \s, but is part of the POSIX "space" class.)
25    4.  A partial match never returns an empty string (because you can always
26        match an empty string at the end of the subject); however the checking for
27        an empty string was starting at the "start of match" point. This has been
28        changed to the "earliest inspected character" point, because the returned
29        data for a partial match starts at this character. This means that, for
30        example, /(?<=abc)def/ gives a partial match for the subject "abc"
31        (previously it gave "no match").
33    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
34        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
35        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
36        has an implication that the given string is incomplete (because a partial
37        match is preferred over a full match). For this reason, these items now
38        give a partial match in this situation. [Aside: previously, the one case
39        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
40        match rather than a full match, which was wrong by the old rules, but is
41        now correct.]
43    6.  There was a bug in the handling of #-introduced comments, recognized when
44        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
45        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
46        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
47        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
48        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
49        places in pcre_compile().
51    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
52        comments when looking ahead for named forward references to subpatterns,
53        the only newline sequence it recognized was NL. It now handles newlines
54        according to the set newline convention.
56    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
57        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
58        cater for a lack of strerror(). These oversights have been fixed.
60    9.  Added --match-limit and --recursion-limit to pcregrep.
62    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
64    11. When the -o option was used, pcregrep was setting a return code of 1, even
65        when matches were found, and --line-buffered was not being honoured.
67    12. Added an optional parentheses number to the -o and --only-matching options
68        of pcregrep.
70    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
71        can match an empty string. The code to do it in pcretest and pcredemo
72        needed fixing:
74        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
75            only one byte after an empty string match just before CRLF (this case
76            just got forgotten; "any" and "anycrlf" were OK).
78        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
79            mode when an empty string match preceded an ASCII character followed by
80            a non-ASCII character. (The code for advancing by one character rather
81            than one byte was nonsense.)
83        (c) The pcredemo.c sample program did not have any code at all to handle
84            the cases when CRLF is a valid newline sequence.
86    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
87        as a starting offset was within the subject string. There is now a new
88        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
89        negative or greater than the length of the string. In order to test this,
90        pcretest is extended to allow the setting of negative starting offsets.
92    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
93        starting offset points to the beginning of a UTF-8 character was
94        unnecessarily clumsy. I tidied it up.
96    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
97        bad UTF-8 sequence and one that is incomplete.
100    Version 8.10 25-Jun-2010
101    ------------------------
103    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
104        THEN.
106    2.  (*ACCEPT) was not working when inside an atomic group.
108    3.  Inside a character class, \B is treated as a literal by default, but
109        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
110        causes the error). The code is unchanged, but I tidied the documentation.
112    4.  Inside a character class, PCRE always treated \R and \X as literals,
113        whereas Perl faults them if its -w option is set. I have changed PCRE so
114        that it faults them when PCRE_EXTRA is set.
116    5.  Added support for \N, which always matches any character other than
117        newline. (It is the same as "." when PCRE_DOTALL is not set.)
119    6.  When compiling pcregrep with newer versions of gcc which may have
120        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
121        declared with attribute warn_unused_result" were given. Just casting the
122        result to (void) does not stop the warnings; a more elaborate fudge is
123        needed. I've used a macro to implement this.
125    7.  Minor change to pcretest.c to avoid a compiler warning.
127    8.  Added four artifical Unicode properties to help with an option to make
128        \s etc use properties (see next item). The new properties are: Xan
129        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
131    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
132        use Unicode properties. (*UCP) at the start of a pattern can be used to set
133        this option. Modified pcretest to add /W to test this facility. Added
134        REG_UCP to make it available via the POSIX interface.
136    10. Added --line-buffered to pcregrep.
138    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
139        studied, and the match started with a letter with a code point greater than
140        127 whose first byte was different to the first byte of the other case of
141        the letter, the other case of this starting letter was not recognized
142        (#976).
144    12. If a pattern that was studied started with a repeated Unicode property
145        test, for example, \p{Nd}+, there was the theoretical possibility of
146        setting up an incorrect bitmap of starting bytes, but fortunately it could
147        not have actually happened in practice until change 8 above was made (it
148        added property types that matched character-matching opcodes).
150    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
151        possible starting bytes for non-anchored patterns.
153    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
154        \R, and also a number of cases that involve Unicode properties, both
155        explicit and implicit when PCRE_UCP is set.
157    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
158        input, it could crash or give wrong results if characters with values
159        greater than 0xc0 were present in the subject string. (Detail: it assumed
160        UTF-8 input when processing these items.)
162    16. Added a lot of (int) casts to avoid compiler warnings in systems where
163        size_t is 64-bit (#991).
165    17. Added a check for running out of memory when PCRE is compiled with
166        --disable-stack-for-recursion (#990).
168    18. If the last data line in a file for pcretest does not have a newline on
169        the end, a newline was missing in the output.
171    19. The default pcre_chartables.c file recognizes only ASCII characters (values
172        less than 128) in its various bitmaps. However, there is a facility for
173        generating tables according to the current locale when PCRE is compiled. It
174        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
175        characters, are recognized by isspace() and therefore were getting set in
176        these tables, and indeed these tables seem to approximate to ISO 8859. This
177        caused a problem in UTF-8 mode when pcre_study() was used to create a list
178        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
179        which of course cannot start UTF-8 characters. I have changed the code so
180        that only real ASCII characters (less than 128) and the correct starting
181        bytes for UTF-8 encodings are set for characters greater than 127 when in
182        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
183        altogether.)
185    20. Added the /T option to pcretest so as to be able to run tests with non-
186        standard character tables, thus making it possible to include the tests
187        used for 19 above in the standard set of tests.
189    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
190        reference to a subpattern the other side of a comment that contains an
191        opening parenthesis caused either an internal compiling error, or a
192        reference to the wrong subpattern.
195    Version 8.02 19-Mar-2010
196    ------------------------
198    1.  The Unicode data tables have been updated to Unicode 5.2.0.
200    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
201        configured.
203    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
204        original author of that file, following a query about its status.
206    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
207        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
209    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
210        quantifier applied to a forward-referencing subroutine call, could compile
211        incorrect code or give the error "internal error: previously-checked
212        referenced subpattern not found".
214    6.  Both MS Visual Studio and Symbian OS have problems with initializing
215        variables to point to external functions. For these systems, therefore,
216        pcre_malloc etc. are now initialized to local functions that call the
217        relevant global functions.
219    7.  There were two entries missing in the vectors called coptable and poptable
220        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
221        I've fixed the data, and added a kludgy way of testing at compile time that
222        the lengths are correct (equal to the number of opcodes).
224    8.  Following on from 7, I added a similar kludge to check the length of the
225        eint vector in pcreposix.c.
227    9.  Error texts for pcre_compile() are held as one long string to avoid too
228        much relocation at load time. To find a text, the string is searched,
229        counting zeros. There was no check for running off the end of the string,
230        which could happen if a new error number was added without updating the
231        string.
233    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
235    11. \K was not working if it appeared in an atomic group or in a group that
236        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
237        \K is "not well defined" if used in an assertion. PCRE now accepts it if
238        the assertion is positive, but not if it is negative.
240    12. Change 11 fortuitously reduced the size of the stack frame used in the
241        "match()" function of pcre_exec.c by one pointer. Forthcoming
242        implementation of support for (*MARK) will need an extra pointer on the
243        stack; I have reserved it now, so that the stack frame size does not
244        decrease.
246    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
247        item in branch that calls a recursion is a subroutine call - as in the
248        second branch in the above example - was incorrectly given the compile-
249        time error "recursive call could loop indefinitely" because pcre_compile()
250        was not correctly checking the subroutine for matching a non-empty string.
252    14. The checks for overrunning compiling workspace could trigger after an
253        overrun had occurred. This is a "should never occur" error, but it can be
254        triggered by pathological patterns such as hundreds of nested parentheses.
255        The checks now trigger 100 bytes before the end of the workspace.
257    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
260    Version 8.01 19-Jan-2010
261    ------------------------
263    1.  If a pattern contained a conditional subpattern with only one branch (in
264        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
265        computed the wrong minimum data length (which is of course zero for such
266        subpatterns). This could cause incorrect "no match" results.
268    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
269        the pattern is reset in the first branch, pcre_compile() failed with
270        "internal error: code overflow at offset...". This happened only when
271        the reset was to the original external option setting. (An optimization
272        abstracts leading options settings into an external setting, which was the
273        cause of this.)
275    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
276        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
277        assertion pattern did not match (meaning that the assertion was true), it
278        was incorrectly treated as false if the SKIP had been reached during the
279        matching. This also applied to assertions used as conditions.
281    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
282        assertion subpattern, including such a pattern used as a condition,
283        unpredictable results occurred, instead of the error return
286    5.  The C++ GlobalReplace function was not working like Perl for the special
287        situation when an empty string is matched. It now does the fancy magic
288        stuff that is necessary.
290    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
291        removed. (These were left over from very, very early versions of PCRE.)
293    7.  Some cosmetic changes to the code to make life easier when compiling it
294        as part of something else:
296        (a) Change DEBUG to PCRE_DEBUG.
298        (b) In pcre_compile(), rename the member of the "branch_chain" structure
299            called "current" as "current_branch", to prevent a collision with the
300            Linux macro when compiled as a kernel module.
302        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
303            prevent a collision with the Linux macro when compiled as a kernel
304            module.
306    8.  In pcre_compile() there are some checks for integer overflows that used to
307        cast potentially large values to (double). This has been changed to that
308        when building, a check for int64_t is made, and if it is found, it is used
309        instead, thus avoiding the use of floating point arithmetic. (There is no
310        other use of FP in PCRE.) If int64_t is not found, the fallback is to
311        double.
313    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
314        2005 (difference between two addresses compared to an unsigned value).
316    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
317        custom one, because of the following reported problem in Windows:
319          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
320              under Win32.
321          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
322              therefore missing the function definition.
323          - The compiler thus generates a "C" signature for the test function.
324          - The linker fails to find the "C" function.
325          - PCRE fails to configure if asked to do so against libbz2.
327    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
328        messages were output:
330          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
331          rerunning libtoolize, to keep the correct libtool macros in-tree.
332          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
334        I have done both of these things.
336    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
337        most of the time, it *can* run out if it is given a pattern that contains a
338        runaway infinite recursion. I updated the discussion in the pcrestack man
339        page.
341    13. Now that we have gone to the x.xx style of version numbers, the minor
342        version may start with zero. Using 08 or 09 is a bad idea because users
343        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
344        interpreted as invalid octal numbers. I've updated the previous comment in
345        configure.ac, and also added a check that gives an error if 08 or 09 are
346        used.
348    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
349        causing partial matching to fail when the end of the subject matched \W
350        in a UTF-8 pattern where \W was quantified with a minimum of 3.
352    15. There were some discrepancies between the declarations in pcre_internal.h
353        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
354        their definitions. The declarations used "const uschar *" and the
355        definitions used USPTR. Even though USPTR is normally defined as "const
356        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
357        reported that: "This difference in casting confuses some C++ compilers, for
358        example, SunCC recognizes above declarations as different functions and
359        generates broken code for hbpcre." I have changed the declarations to use
360        USPTR.
362    16. GNU libtool is named differently on some systems. The autogen.sh script now
363        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
364        (FreeBSD).
366    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
367        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
368        comment: "Figure out how to create a longlong from a string: strtoll and
369        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
370        instance, but it only takes 2 args instead of 3!"
372    18. A subtle bug concerned with back references has been fixed by a change of
373        specification, with a corresponding code fix. A pattern such as
374        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
375        refers, was giving matches when it shouldn't. For example, xa=xaaa would
376        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
377        same bug. Such groups have to be quantified to be useful, or contained
378        inside another quantified group. (If there's no repetition, the reference
379        can never match.) The problem arises because, having left the group and
380        moved on to the rest of the pattern, a later failure that backtracks into
381        the group uses the captured value from the final iteration of the group
382        rather than the correct earlier one. I have fixed this in PCRE by forcing
383        any group that contains a reference to itself to be an atomic group; that
384        is, there cannot be any backtracking into it once it has completed. This is
385        similar to recursive and subroutine calls.
388    Version 8.00 19-Oct-09
389    ----------------------
391    1.  The table for translating pcre_compile() error codes into POSIX error codes
392        was out-of-date, and there was no check on the pcre_compile() error code
393        being within the table. This could lead to an OK return being given in
394        error.
396    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
397        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
398        in a Windows environment.
400    3.  The pcregrep --count option prints the count for each file even when it is
401        zero, as does GNU grep. However, pcregrep was also printing all files when
402        --files-with-matches was added. Now, when both options are given, it prints
403        counts only for those files that have at least one match. (GNU grep just
404        prints the file name in this circumstance, but including the count seems
405        more useful - otherwise, why use --count?) Also ensured that the
406        combination -clh just lists non-zero counts, with no names.
408    4.  The long form of the pcregrep -F option was incorrectly implemented as
409        --fixed_strings instead of --fixed-strings. This is an incompatible change,
410        but it seems right to fix it, and I didn't think it was worth preserving
411        the old behaviour.
413    5.  The command line items --regex=pattern and --regexp=pattern were not
414        recognized by pcregrep, which required --regex pattern or --regexp pattern
415        (with a space rather than an '='). The man page documented the '=' forms,
416        which are compatible with GNU grep; these now work.
418    6.  No libpcreposix.pc file was created for pkg-config; there was just
419        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
421    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
422        when UCP support is not needed, by modifying the Python script that
423        generates it from Unicode data files. This should not matter if the module
424        is correctly used as a library, but I received one complaint about 50K of
425        unwanted data. My guess is that the person linked everything into his
426        program rather than using a library. Anyway, it does no harm.
428    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
429        was a minimum greater than 1 for a wide character in a possessive
430        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
431        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
432        character. Chaos in the form of incorrect output or a compiling loop could
433        result.
435    9.  The restrictions on what a pattern can contain when partial matching is
436        requested for pcre_exec() have been removed. All patterns can now be
437        partially matched by this function. In addition, if there are at least two
438        slots in the offset vector, the offset of the earliest inspected character
439        for the match and the offset of the end of the subject are set in them when
440        PCRE_ERROR_PARTIAL is returned.
442    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
443        synonymous with PCRE_PARTIAL, for backwards compatibility, and
444        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
445        and may be more useful for multi-segment matching.
447    11. Partial matching with pcre_exec() is now more intuitive. A partial match
448        used to be given if ever the end of the subject was reached; now it is
449        given only if matching could not proceed because another character was
450        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
451        string "Z", which now yields "no match" instead of "partial match". In the
452        case of pcre_dfa_exec(), "no match" is given if every matching path for the
453        final character ended with (*FAIL).
455    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
456        if the pattern had a "must contain" character that was already found in the
457        earlier partial match, unless partial matching was again requested. For
458        example, with the pattern /dog.(body)?/, the "must contain" character is
459        "g". If the first part-match was for the string "dog", restarting with
460        "sbody" failed. This bug has been fixed.
462    13. The string returned by pcre_dfa_exec() after a partial match has been
463        changed so that it starts at the first inspected character rather than the
464        first character of the match. This makes a difference only if the pattern
465        starts with a lookbehind assertion or \b or \B (\K is not supported by
466        pcre_dfa_exec()). It's an incompatible change, but it makes the two
467        matching functions compatible, and I think it's the right thing to do.
469    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
470        so that the demonstration program is easily available in environments where
471        PCRE has not been installed from source.
473    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
474        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
475        library.
477    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
478        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
479        is not the first non-POSIX option to be added. Clearly some people find
480        these options useful.
482    17. If a caller to the POSIX matching function regexec() passes a non-zero
483        value for nmatch with a NULL value for pmatch, the value of
484        nmatch is forced to zero.
486    18. RunGrepTest did not have a test for the availability of the -u option of
487        the diff command, as RunTest does. It now checks in the same way as
488        RunTest, and also checks for the -b option.
490    19. If an odd number of negated classes containing just a single character
491        interposed, within parentheses, between a forward reference to a named
492        subpattern and the definition of the subpattern, compilation crashed with
493        an internal error, complaining that it could not find the referenced
494        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
495        [The bug was that it was starting one character too far in when skipping
496        over the character class, thus treating the ] as data rather than
497        terminating the class. This meant it could skip too much.]
499    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
500        /g option in pcretest when the pattern contains \K, which makes it possible
501        to have an empty string match not at the start, even when the pattern is
502        anchored. Updated pcretest and pcredemo to use this option.
504    21. If the maximum number of capturing subpatterns in a recursion was greater
505        than the maximum at the outer level, the higher number was returned, but
506        with unset values at the outer level. The correct (outer level) value is
507        now given.
509    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
510        PCRE did not set those parentheses (unlike Perl). I have now found a way to
511        make it do so. The string so far is captured, making this feature
512        compatible with Perl.
514    23. The tests have been re-organized, adding tests 11 and 12, to make it
515        possible to check the Perl 5.10 features against Perl 5.10.
517    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
518        pattern matches a fixed length string. PCRE did not allow this; now it
519        does. Neither allows recursion.
521    25. I finally figured out how to implement a request to provide the minimum
522        length of subject string that was needed in order to match a given pattern.
523        (It was back references and recursion that I had previously got hung up
524        on.) This code has now been added to pcre_study(); it finds a lower bound
525        to the length of subject needed. It is not necessarily the greatest lower
526        bound, but using it to avoid searching strings that are too short does give
527        some useful speed-ups. The value is available to calling programs via
528        pcre_fullinfo().
530    26. While implementing 25, I discovered to my embarrassment that pcretest had
531        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
532        study optimizations had never been tested with that matching function.
533        Oops. What is worse, even when it was passed study data, there was a bug in
534        pcre_dfa_exec() that meant it never actually used it. Double oops. There
535        were also very few tests of studied patterns with pcre_dfa_exec().
537    27. If (?| is used to create subpatterns with duplicate numbers, they are now
538        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
539        on the other side of the coin, they are no longer allowed to have different
540        names, because these cannot be distinguished in PCRE, and this has caused
541        confusion. (This is a difference from Perl.)
543    28. When duplicate subpattern names are present (necessarily with different
544        numbers, as required by 27 above), and a test is made by name in a
545        conditional pattern, either for a subpattern having been matched, or for
546        recursion in such a pattern, all the associated numbered subpatterns are
547        tested, and the overall condition is true if the condition is true for any
548        one of them. This is the way Perl works, and is also more like the way
549        testing by number works.
552    Version 7.9 11-Apr-09
553    ---------------------
555    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
556        (pcretest), all targets were linked against these libraries. This included
557        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
558        libraries. This caused unwanted dependencies to be created. This problem
559        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
560        pcretest is linked with readline.
562    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
563        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
564        moved outside it again, because FALSE and TRUE are already defined in AIX,
565        but BOOL is not.
567    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
568        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
570    4.  The pcregrep documentation said spaces were inserted as well as colons (or
571        hyphens) following file names and line numbers when outputting matching
572        lines. This is not true; no spaces are inserted. I have also clarified the
573        wording for the --colour (or --color) option.
575    5.  In pcregrep, when --colour was used with -o, the list of matching strings
576        was not coloured; this is different to GNU grep, so I have changed it to be
577        the same.
579    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
580        each matching line was coloured. Now it goes on to look for further matches
581        of any of the test patterns, which is the same behaviour as GNU grep.
583    7.  A pattern that could match an empty string could cause pcregrep to loop; it
584        doesn't make sense to accept an empty string match in pcregrep, so I have
585        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
586        seems to be how GNU grep behaves.
588    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
589        start or after a newline", because the conditional assertion was not being
590        correctly handled. The rule now is that both the assertion and what follows
591        in the first alternative must satisfy the test.
593    9.  If auto-callout was enabled in a pattern with a conditional group whose
594        condition was an assertion, PCRE could crash during matching, both with
595        pcre_exec() and pcre_dfa_exec().
597    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
598        used for matching.
600    11. Unicode property support in character classes was not working for
601        characters (bytes) greater than 127 when not in UTF-8 mode.
603    12. Added the -M command line option to pcretest.
605    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
607    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
609    16. Added comments and documentation about mis-use of no_arg in the C++
610        wrapper.
612    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
613        from Martin Jerabek that uses macro names for all relevant character and
614        string constants.
616    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
617        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
618        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
619        these, but not everybody uses configure.
621    19. A conditional group that had only one branch was not being correctly
622        recognized as an item that could match an empty string. This meant that an
623        enclosing group might also not be so recognized, causing infinite looping
624        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
625        with the subject "ab", where knowledge that the repeated group can match
626        nothing is needed in order to break the loop.
628    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
629        exec(), but without supplying a callout function, matching went wrong.
631    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
632        leak if the size of the offset vector was greater than 30. When the vector
633        is smaller, the saved offsets during recursion go onto a local stack
634        vector, but for larger vectors malloc() is used. It was failing to free
635        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
636        error, in fact).
638    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
639        heapframe that is used only when UTF-8 support is enabled. This caused no
640        problem, but was untidy.
642    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
643        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
644        included within another project.
646    24. Steven Van Ingelgem's patches to add more options to the CMake support,
647        slightly modified by me:
649          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
650              not building pcregrep.
652          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
653              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
655    25. Forward references, both numeric and by name, in patterns that made use of
656        duplicate group numbers, could behave incorrectly or give incorrect errors,
657        because when scanning forward to find the reference group, PCRE was not
658        taking into account the duplicate group numbers. A pattern such as
659        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
661    26. Changed a few more instances of "const unsigned char *" to USPTR, making
662        the feature of a custom pointer more persuasive (as requested by a user).
664    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
665        pcretest.c, inside #ifndefs, because it seems they are sometimes already
666        pre-defined.
668    28. Added support for (*UTF8) at the start of a pattern.
670    29. Arrange for flags added by the "release type" setting in CMake to be shown
671        in the configuration summary.
674    Version 7.8 05-Sep-08
675    ---------------------
677    1.  Replaced UCP searching code with optimized version as implemented for Ad
678        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
679        stage table and inline lookup instead of a function, giving speed ups of 2
680        to 5 times on some simple patterns that I tested. Permission was given to
681        distribute the MultiStage2.py script that generates the tables (it's not in
682        the tarball, but is in the Subversion repository).
684    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
685        scripts.
687    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
688        a group with a zero qualifier. The result of the study could be incorrect,
689        or the function might crash, depending on the pattern.
691    4.  Caseless matching was not working for non-ASCII characters in back
692        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
693        It now works when Unicode Property Support is available.
695    5.  In pcretest, an escape such as \x{de} in the data was always generating
696        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
697        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
698        truncation.
700    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
702    7.  Added two (int) casts to pcregrep when printing the difference of two
703        pointers, in case they are 64-bit values.
705    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
706        test 2 if it fails.
708    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
709        and a #define of that name to empty if it is not externally set. This is to
710        allow users of MSVC to set it if necessary.
712    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
713        the convenience functions in the pcre_get.c source file.
715    11. An option change at the start of a pattern that had top-level alternatives
716        could cause overwriting and/or a crash. This command provoked a crash in
717        some environments:
719          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
721        This potential security problem was recorded as CVE-2008-2371.
723    12. For a pattern where the match had to start at the beginning or immediately
724        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
725        pcre_dfa_exec() could read past the end of the passed subject if there was
726        no match. To help with detecting such bugs (e.g. with valgrind), I modified
727        pcretest so that it places the subject at the end of its malloc-ed buffer.
729    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
730        exec() might read past the end of the data buffer in UTF-8 mode.
732    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
733        the data contained the byte 0x85 as part of a UTF-8 character within its
734        first line. This applied both to normal and DFA matching.
736    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
737        /^[^d]*?$/8 failed to match "abc".
739    16. Added a missing copyright notice to pcrecpp_internal.h.
741    17. Make it more clear in the documentation that values returned from
742        pcre_exec() in ovector are byte offsets, not character counts.
744    18. Tidied a few places to stop certain compilers from issuing warnings.
746    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
747        supplied by Stefan Weber. I made a further small update for 7.8 because
748        there is a change of source arrangements: the pcre_searchfuncs.c module is
749        replaced by pcre_ucd.c.
752    Version 7.7 07-May-08
753    ---------------------
755    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
756        a string to a long long, pretend we don't even have a long long." This is
757        done by checking for the strtoq, strtoll, and _strtoi64 functions.
759    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
760        pre-7.6 versions, which defined a global no_arg variable instead of putting
761        it in the RE class. (See also #8 below.)
763    3.  Remove a line of dead code, identified by coverity and reported by Nuno
764        Lopes.
766    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
768        (1) The include/exclude patterns were being applied to the whole pathnames
769            of files, instead of just to the final components.
771        (2) If there was more than one level of directory, the subdirectories were
772            skipped unless they satisfied the include/exclude conditions. This is
773            inconsistent with GNU grep (and could even be seen as contrary to the
774            pcregrep specification - which I improved to make it absolutely clear).
775            The action now is always to scan all levels of directory, and just
776            apply the include/exclude patterns to regular files.
778    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
779        --exclude_dir in the tests to avoid scanning .svn directories.
781    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
782        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
783        doesn't support NULs in patterns.
785    7.  Added some missing "const"s to declarations of static tables in
786        pcre_compile.c and pcre_dfa_exec.c.
788    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
789        caused by fix #2  above. (Subsequently also a second patch to fix the
790        first patch. And a third patch - this was a messy problem.)
792    9.  Applied Craig's patch to remove the use of push_back().
794    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
795        matching function regexec().
797    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
798        which, however, unlike Perl's \g{...}, are subroutine calls, not back
799        references. PCRE supports relative numbers with this syntax (I don't think
800        Oniguruma does).
802    12. Previously, a group with a zero repeat such as (...){0} was completely
803        omitted from the compiled regex. However, this means that if the group
804        was called as a subroutine from elsewhere in the pattern, things went wrong
805        (an internal error was given). Such groups are now left in the compiled
806        pattern, with a new opcode that causes them to be skipped at execution
807        time.
809    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
810        to the way PCRE behaves:
812        (a) A lone ] character is dis-allowed (Perl treats it as data).
814        (b) A back reference to an unmatched subpattern matches an empty string
815            (Perl fails the current match path).
817        (c) A data ] in a character class must be notated as \] because if the
818            first data character in a class is ], it defines an empty class. (In
819            Perl it is not possible to have an empty class.) The empty class []
820            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
821            The negative empty class [^] matches any one character, independently
822            of the DOTALL setting.
824    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
825        non-existent subpattern following a character class starting with ']' and
826        containing () gave an internal compiling error instead of "reference to
827        non-existent subpattern". Fortunately, when the pattern did exist, the
828        compiled code was correct. (When scanning forwards to check for the
829        existencd of the subpattern, it was treating the data ']' as terminating
830        the class, so got the count wrong. When actually compiling, the reference
831        was subsequently set up correctly.)
833    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
834        it was being rejected as not supported by pcre_dfa_exec(), even though
835        other assertions are supported. I have made pcre_dfa_exec() support
836        (*FAIL).
838    16. The implementation of 13c above involved the invention of a new opcode,
839        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
840        cannot be changed at match time, I realized I could make a small
841        improvement to matching performance by compiling OP_ALLANY instead of
842        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
843        on the OP_ANY path.
845    17. Compiling pcretest on Windows with readline support failed without the
846        following two fixes: (1) Make the unistd.h include conditional on
847        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
849    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
850        ncurses library to be included for pcretest when ReadLine support is
851        requested, but also to allow for it to be overridden. This patch came from
852        Daniel Bergström.
854    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
855        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
856        any errors with the current Unicode tables. Thanks to Peter Kankowski for
857        spotting this.
860    Version 7.6 28-Jan-08
861  ---------------------  ---------------------
863  1.  A character class containing a very large number of characters with  1.  A character class containing a very large number of characters with
864      codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer      codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
865      overflow.      overflow.
867  2.  Patch to cut out the "long long" test in pcrecpp_unittest when  2.  Patch to cut out the "long long" test in pcrecpp_unittest when
868      HAVE_LONG_LONG is not defined.      HAVE_LONG_LONG is not defined.
870  3.  Applied Christian Ehrlicher's patch to update the CMake build files to  3.  Applied Christian Ehrlicher's patch to update the CMake build files to
871      bring them up to date and include new features. This patch includes:      bring them up to date and include new features. This patch includes:
873      - Fixed PH's badly added libz and libbz2 support.      - Fixed PH's badly added libz and libbz2 support.
874      - Fixed a problem with static linking.      - Fixed a problem with static linking.
875      - Added pcredemo.      - Added pcredemo. [But later removed - see 7 below.]
876      - Fixed dftables problem and added an option.      - Fixed dftables problem and added an option.
877      - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and      - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
878          HAVE_LONG_LONG.          HAVE_LONG_LONG.
879      - Added readline support for pcretest.      - Added readline support for pcretest.
880      - Added an listing of the option settings after cmake has run.      - Added an listing of the option settings after cmake has run.
882    4.  A user submitted a patch to Makefile that makes it easy to create
883        "pcre.dll" under mingw when using Configure/Make. I added stuff to
884        Makefile.am that cause it to include this special target, without
885        affecting anything else. Note that the same mingw target plus all
886        the other distribution libraries and programs are now supported
887        when configuring with CMake (see 6 below) instead of with
888        Configure/Make.
890    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
891        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
892        exported in the Windows port". It has not yet been confirmed that the patch
893        solves the problem, but it does no harm.
895    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
896        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
897        with CMake, and also correct the comment about stack recursion.
899    7.  Remove the automatic building of pcredemo from the ./configure system and
900        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
901        of a program that users should build themselves after PCRE is installed, so
902        building it automatically is not really right. What is more, it gave
903        trouble in some build environments.
905    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
908  Version 7.5 10-Jan-08  Version 7.5 10-Jan-08
909  ---------------------  ---------------------

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