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revision 419 by ph10, Wed Aug 12 10:45:33 2009 UTC revision 489 by ph10, Tue Jan 19 16:42:21 2010 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 8.00 ??-???-??  Version 8.01 19-Jan-2010
5    ------------------------
7    1.  If a pattern contained a conditional subpattern with only one branch (in
8        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
9        computed the wrong minimum data length (which is of course zero for such
10        subpatterns). This could cause incorrect "no match" results.
12    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
13        the pattern is reset in the first branch, pcre_compile() failed with
14        "internal error: code overflow at offset...". This happened only when
15        the reset was to the original external option setting. (An optimization
16        abstracts leading options settings into an external setting, which was the
17        cause of this.)
19    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
20        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
21        assertion pattern did not match (meaning that the assertion was true), it
22        was incorrectly treated as false if the SKIP had been reached during the
23        matching. This also applied to assertions used as conditions.
25    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
26        assertion subpattern, including such a pattern used as a condition,
27        unpredictable results occurred, instead of the error return
30    5.  The C++ GlobalReplace function was not working like Perl for the special
31        situation when an empty string is matched. It now does the fancy magic
32        stuff that is necessary.
34    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
35        removed. (These were left over from very, very early versions of PCRE.)
37    7.  Some cosmetic changes to the code to make life easier when compiling it
38        as part of something else:
40        (a) Change DEBUG to PCRE_DEBUG.
42        (b) In pcre_compile(), rename the member of the "branch_chain" structure
43            called "current" as "current_branch", to prevent a collision with the
44            Linux macro when compiled as a kernel module.
46        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
47            prevent a collision with the Linux macro when compiled as a kernel
48            module.
50    8.  In pcre_compile() there are some checks for integer overflows that used to
51        cast potentially large values to (double). This has been changed to that
52        when building, a check for int64_t is made, and if it is found, it is used
53        instead, thus avoiding the use of floating point arithmetic. (There is no
54        other use of FP in PCRE.) If int64_t is not found, the fallback is to
55        double.
57    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
58        2005 (difference between two addresses compared to an unsigned value).
60    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
61        custom one, because of the following reported problem in Windows:
63          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
64              under Win32.
65          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
66              therefore missing the function definition.
67          - The compiler thus generates a "C" signature for the test function.
68          - The linker fails to find the "C" function.
69          - PCRE fails to configure if asked to do so against libbz2.
71    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
72        messages were output:
74          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
75          rerunning libtoolize, to keep the correct libtool macros in-tree.
76          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
78        I have done both of these things.
80    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
81        most of the time, it *can* run out if it is given a pattern that contains a
82        runaway infinite recursion. I updated the discussion in the pcrestack man
83        page.
85    13. Now that we have gone to the x.xx style of version numbers, the minor
86        version may start with zero. Using 08 or 09 is a bad idea because users
87        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
88        interpreted as invalid octal numbers. I've updated the previous comment in
89        configure.ac, and also added a check that gives an error if 08 or 09 are
90        used.
92    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
93        causing partial matching to fail when the end of the subject matched \W
94        in a UTF-8 pattern where \W was quantified with a minimum of 3.
96    15. There were some discrepancies between the declarations in pcre_internal.h
97        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
98        their definitions. The declarations used "const uschar *" and the
99        definitions used USPTR. Even though USPTR is normally defined as "const
100        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
101        reported that: "This difference in casting confuses some C++ compilers, for
102        example, SunCC recognizes above declarations as different functions and
103        generates broken code for hbpcre." I have changed the declarations to use
104        USPTR.
106    16. GNU libtool is named differently on some systems. The autogen.sh script now
107        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
108        (FreeBSD).
110    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
111        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
112        comment: "Figure out how to create a longlong from a string: strtoll and
113        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
114        instance, but it only takes 2 args instead of 3!"
116    18. A subtle bug concerned with back references has been fixed by a change of
117        specification, with a corresponding code fix. A pattern such as
118        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
119        refers, was giving matches when it shouldn't. For example, xa=xaaa would
120        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
121        same bug. Such groups have to be quantified to be useful, or contained
122        inside another quantified group. (If there's no repetition, the reference
123        can never match.) The problem arises because, having left the group and
124        moved on to the rest of the pattern, a later failure that backtracks into
125        the group uses the captured value from the final iteration of the group
126        rather than the correct earlier one. I have fixed this in PCRE by forcing
127        any group that contains a reference to itself to be an atomic group; that
128        is, there cannot be any backtracking into it once it has completed. This is
129        similar to recursive and subroutine calls.
132    Version 8.00 19-Oct-09
133  ----------------------  ----------------------
135  1.  The table for translating pcre_compile() error codes into POSIX error codes  1.  The table for translating pcre_compile() error codes into POSIX error codes
136      was out-of-date, and there was no check on the pcre_compile() error code      was out-of-date, and there was no check on the pcre_compile() error code
137      being within the table. This could lead to an OK return being given in      being within the table. This could lead to an OK return being given in
138      error.      error.
140  2.  Changed the call to open a subject file in pcregrep from fopen(pathname,  2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
141      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
142      in a Windows environment.      in a Windows environment.
144    3.  The pcregrep --count option prints the count for each file even when it is
145        zero, as does GNU grep. However, pcregrep was also printing all files when
146        --files-with-matches was added. Now, when both options are given, it prints
147        counts only for those files that have at least one match. (GNU grep just
148        prints the file name in this circumstance, but including the count seems
149        more useful - otherwise, why use --count?) Also ensured that the
150        combination -clh just lists non-zero counts, with no names.
152    4.  The long form of the pcregrep -F option was incorrectly implemented as
153        --fixed_strings instead of --fixed-strings. This is an incompatible change,
154        but it seems right to fix it, and I didn't think it was worth preserving
155        the old behaviour.
157    5.  The command line items --regex=pattern and --regexp=pattern were not
158        recognized by pcregrep, which required --regex pattern or --regexp pattern
159        (with a space rather than an '='). The man page documented the '=' forms,
160        which are compatible with GNU grep; these now work.
162    6.  No libpcreposix.pc file was created for pkg-config; there was just
163        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
165    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
166        when UCP support is not needed, by modifying the Python script that
167        generates it from Unicode data files. This should not matter if the module
168        is correctly used as a library, but I received one complaint about 50K of
169        unwanted data. My guess is that the person linked everything into his
170        program rather than using a library. Anyway, it does no harm.
172    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
173        was a minimum greater than 1 for a wide character in a possessive
174        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
175        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
176        character. Chaos in the form of incorrect output or a compiling loop could
177        result.
179    9.  The restrictions on what a pattern can contain when partial matching is
180        requested for pcre_exec() have been removed. All patterns can now be
181        partially matched by this function. In addition, if there are at least two
182        slots in the offset vector, the offset of the earliest inspected character
183        for the match and the offset of the end of the subject are set in them when
184        PCRE_ERROR_PARTIAL is returned.
186    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
187        synonymous with PCRE_PARTIAL, for backwards compatibility, and
188        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
189        and may be more useful for multi-segment matching.
191    11. Partial matching with pcre_exec() is now more intuitive. A partial match
192        used to be given if ever the end of the subject was reached; now it is
193        given only if matching could not proceed because another character was
194        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
195        string "Z", which now yields "no match" instead of "partial match". In the
196        case of pcre_dfa_exec(), "no match" is given if every matching path for the
197        final character ended with (*FAIL).
199    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
200        if the pattern had a "must contain" character that was already found in the
201        earlier partial match, unless partial matching was again requested. For
202        example, with the pattern /dog.(body)?/, the "must contain" character is
203        "g". If the first part-match was for the string "dog", restarting with
204        "sbody" failed. This bug has been fixed.
206    13. The string returned by pcre_dfa_exec() after a partial match has been
207        changed so that it starts at the first inspected character rather than the
208        first character of the match. This makes a difference only if the pattern
209        starts with a lookbehind assertion or \b or \B (\K is not supported by
210        pcre_dfa_exec()). It's an incompatible change, but it makes the two
211        matching functions compatible, and I think it's the right thing to do.
213    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
214        so that the demonstration program is easily available in environments where
215        PCRE has not been installed from source.
217    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
218        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
219        library.
221    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
222        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
223        is not the first non-POSIX option to be added. Clearly some people find
224        these options useful.
226    17. If a caller to the POSIX matching function regexec() passes a non-zero
227        value for nmatch with a NULL value for pmatch, the value of
228        nmatch is forced to zero.
230    18. RunGrepTest did not have a test for the availability of the -u option of
231        the diff command, as RunTest does. It now checks in the same way as
232        RunTest, and also checks for the -b option.
234    19. If an odd number of negated classes containing just a single character
235        interposed, within parentheses, between a forward reference to a named
236        subpattern and the definition of the subpattern, compilation crashed with
237        an internal error, complaining that it could not find the referenced
238        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
239        [The bug was that it was starting one character too far in when skipping
240        over the character class, thus treating the ] as data rather than
241        terminating the class. This meant it could skip too much.]
243    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
244        /g option in pcretest when the pattern contains \K, which makes it possible
245        to have an empty string match not at the start, even when the pattern is
246        anchored. Updated pcretest and pcredemo to use this option.
248    21. If the maximum number of capturing subpatterns in a recursion was greater
249        than the maximum at the outer level, the higher number was returned, but
250        with unset values at the outer level. The correct (outer level) value is
251        now given.
253    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
254        PCRE did not set those parentheses (unlike Perl). I have now found a way to
255        make it do so. The string so far is captured, making this feature
256        compatible with Perl.
258    23. The tests have been re-organized, adding tests 11 and 12, to make it
259        possible to check the Perl 5.10 features against Perl 5.10.
261    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
262        pattern matches a fixed length string. PCRE did not allow this; now it
263        does. Neither allows recursion.
265    25. I finally figured out how to implement a request to provide the minimum
266        length of subject string that was needed in order to match a given pattern.
267        (It was back references and recursion that I had previously got hung up
268        on.) This code has now been added to pcre_study(); it finds a lower bound
269        to the length of subject needed. It is not necessarily the greatest lower
270        bound, but using it to avoid searching strings that are too short does give
271        some useful speed-ups. The value is available to calling programs via
272        pcre_fullinfo().
274    26. While implementing 25, I discovered to my embarrassment that pcretest had
275        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
276        study optimizations had never been tested with that matching function.
277        Oops. What is worse, even when it was passed study data, there was a bug in
278        pcre_dfa_exec() that meant it never actually used it. Double oops. There
279        were also very few tests of studied patterns with pcre_dfa_exec().
281    27. If (?| is used to create subpatterns with duplicate numbers, they are now
282        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
283        on the other side of the coin, they are no longer allowed to have different
284        names, because these cannot be distinguished in PCRE, and this has caused
285        confusion. (This is a difference from Perl.)
287    28. When duplicate subpattern names are present (necessarily with different
288        numbers, as required by 27 above), and a test is made by name in a
289        conditional pattern, either for a subpattern having been matched, or for
290        recursion in such a pattern, all the associated numbered subpatterns are
291        tested, and the overall condition is true if the condition is true for any
292        one of them. This is the way Perl works, and is also more like the way
293        testing by number works.
296  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09

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