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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 8.02 19-Mar-2010
5    ------------------------
6    
7    1.  The Unicode data tables have been updated to Unicode 5.2.0.
8    
9    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
10        configured.
11    
12    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
13        original author of that file, following a query about its status.
14    
15    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
16        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
17    
18    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
19        quantifier applied to a forward-referencing subroutine call, could compile
20        incorrect code or give the error "internal error: previously-checked
21        referenced subpattern not found".
22    
23    6.  Both MS Visual Studio and Symbian OS have problems with initializing
24        variables to point to external functions. For these systems, therefore,
25        pcre_malloc etc. are now initialized to local functions that call the
26        relevant global functions.
27    
28    7.  There were two entries missing in the vectors called coptable and poptable
29        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
30        I've fixed the data, and added a kludgy way of testing at compile time that
31        the lengths are correct (equal to the number of opcodes).
32    
33    8.  Following on from 7, I added a similar kludge to check the length of the
34        eint vector in pcreposix.c.
35    
36    9.  Error texts for pcre_compile() are held as one long string to avoid too
37        much relocation at load time. To find a text, the string is searched,
38        counting zeros. There was no check for running off the end of the string,
39        which could happen if a new error number was added without updating the
40        string.
41    
42    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
43    
44    11. \K was not working if it appeared in an atomic group or in a group that
45        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
46        \K is "not well defined" if used in an assertion. PCRE now accepts it if
47        the assertion is positive, but not if it is negative.
48    
49    12. Change 11 fortuitously reduced the size of the stack frame used in the
50        "match()" function of pcre_exec.c by one pointer. Forthcoming
51        implementation of support for (*MARK) will need an extra pointer on the
52        stack; I have reserved it now, so that the stack frame size does not
53        decrease.
54    
55    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
56        item in branch that calls a recursion is a subroutine call - as in the
57        second branch in the above example - was incorrectly given the compile-
58        time error "recursive call could loop indefinitely" because pcre_compile()
59        was not correctly checking the subroutine for matching a non-empty string.
60    
61    14. The checks for overrunning compiling workspace could trigger after an
62        overrun had occurred. This is a "should never occur" error, but it can be
63        triggered by pathological patterns such as hundreds of nested parentheses.
64        The checks now trigger 100 bytes before the end of the workspace.
65    
66    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
67    
68    
69    Version 8.01 19-Jan-2010
70    ------------------------
71    
72    1.  If a pattern contained a conditional subpattern with only one branch (in
73        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
74        computed the wrong minimum data length (which is of course zero for such
75        subpatterns). This could cause incorrect "no match" results.
76    
77    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
78        the pattern is reset in the first branch, pcre_compile() failed with
79        "internal error: code overflow at offset...". This happened only when
80        the reset was to the original external option setting. (An optimization
81        abstracts leading options settings into an external setting, which was the
82        cause of this.)
83    
84    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
85        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
86        assertion pattern did not match (meaning that the assertion was true), it
87        was incorrectly treated as false if the SKIP had been reached during the
88        matching. This also applied to assertions used as conditions.
89    
90    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
91        assertion subpattern, including such a pattern used as a condition,
92        unpredictable results occurred, instead of the error return
93        PCRE_ERROR_DFA_UITEM.
94    
95    5.  The C++ GlobalReplace function was not working like Perl for the special
96        situation when an empty string is matched. It now does the fancy magic
97        stuff that is necessary.
98    
99    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
100        removed. (These were left over from very, very early versions of PCRE.)
101    
102    7.  Some cosmetic changes to the code to make life easier when compiling it
103        as part of something else:
104    
105        (a) Change DEBUG to PCRE_DEBUG.
106    
107        (b) In pcre_compile(), rename the member of the "branch_chain" structure
108            called "current" as "current_branch", to prevent a collision with the
109            Linux macro when compiled as a kernel module.
110    
111        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
112            prevent a collision with the Linux macro when compiled as a kernel
113            module.
114    
115    8.  In pcre_compile() there are some checks for integer overflows that used to
116        cast potentially large values to (double). This has been changed to that
117        when building, a check for int64_t is made, and if it is found, it is used
118        instead, thus avoiding the use of floating point arithmetic. (There is no
119        other use of FP in PCRE.) If int64_t is not found, the fallback is to
120        double.
121    
122    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
123        2005 (difference between two addresses compared to an unsigned value).
124    
125    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
126        custom one, because of the following reported problem in Windows:
127    
128          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
129              under Win32.
130          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
131              therefore missing the function definition.
132          - The compiler thus generates a "C" signature for the test function.
133          - The linker fails to find the "C" function.
134          - PCRE fails to configure if asked to do so against libbz2.
135    
136    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
137        messages were output:
138    
139          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
140          rerunning libtoolize, to keep the correct libtool macros in-tree.
141          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
142    
143        I have done both of these things.
144    
145    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
146        most of the time, it *can* run out if it is given a pattern that contains a
147        runaway infinite recursion. I updated the discussion in the pcrestack man
148        page.
149    
150    13. Now that we have gone to the x.xx style of version numbers, the minor
151        version may start with zero. Using 08 or 09 is a bad idea because users
152        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
153        interpreted as invalid octal numbers. I've updated the previous comment in
154        configure.ac, and also added a check that gives an error if 08 or 09 are
155        used.
156    
157    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
158        causing partial matching to fail when the end of the subject matched \W
159        in a UTF-8 pattern where \W was quantified with a minimum of 3.
160    
161    15. There were some discrepancies between the declarations in pcre_internal.h
162        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
163        their definitions. The declarations used "const uschar *" and the
164        definitions used USPTR. Even though USPTR is normally defined as "const
165        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
166        reported that: "This difference in casting confuses some C++ compilers, for
167        example, SunCC recognizes above declarations as different functions and
168        generates broken code for hbpcre." I have changed the declarations to use
169        USPTR.
170    
171    16. GNU libtool is named differently on some systems. The autogen.sh script now
172        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
173        (FreeBSD).
174    
175    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
176        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
177        comment: "Figure out how to create a longlong from a string: strtoll and
178        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
179        instance, but it only takes 2 args instead of 3!"
180    
181    18. A subtle bug concerned with back references has been fixed by a change of
182        specification, with a corresponding code fix. A pattern such as
183        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
184        refers, was giving matches when it shouldn't. For example, xa=xaaa would
185        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
186        same bug. Such groups have to be quantified to be useful, or contained
187        inside another quantified group. (If there's no repetition, the reference
188        can never match.) The problem arises because, having left the group and
189        moved on to the rest of the pattern, a later failure that backtracks into
190        the group uses the captured value from the final iteration of the group
191        rather than the correct earlier one. I have fixed this in PCRE by forcing
192        any group that contains a reference to itself to be an atomic group; that
193        is, there cannot be any backtracking into it once it has completed. This is
194        similar to recursive and subroutine calls.
195    
196    
197    Version 8.00 19-Oct-09
198    ----------------------
199    
200    1.  The table for translating pcre_compile() error codes into POSIX error codes
201        was out-of-date, and there was no check on the pcre_compile() error code
202        being within the table. This could lead to an OK return being given in
203        error.
204    
205    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
206        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
207        in a Windows environment.
208    
209    3.  The pcregrep --count option prints the count for each file even when it is
210        zero, as does GNU grep. However, pcregrep was also printing all files when
211        --files-with-matches was added. Now, when both options are given, it prints
212        counts only for those files that have at least one match. (GNU grep just
213        prints the file name in this circumstance, but including the count seems
214        more useful - otherwise, why use --count?) Also ensured that the
215        combination -clh just lists non-zero counts, with no names.
216    
217    4.  The long form of the pcregrep -F option was incorrectly implemented as
218        --fixed_strings instead of --fixed-strings. This is an incompatible change,
219        but it seems right to fix it, and I didn't think it was worth preserving
220        the old behaviour.
221    
222    5.  The command line items --regex=pattern and --regexp=pattern were not
223        recognized by pcregrep, which required --regex pattern or --regexp pattern
224        (with a space rather than an '='). The man page documented the '=' forms,
225        which are compatible with GNU grep; these now work.
226    
227    6.  No libpcreposix.pc file was created for pkg-config; there was just
228        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
229    
230    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
231        when UCP support is not needed, by modifying the Python script that
232        generates it from Unicode data files. This should not matter if the module
233        is correctly used as a library, but I received one complaint about 50K of
234        unwanted data. My guess is that the person linked everything into his
235        program rather than using a library. Anyway, it does no harm.
236    
237    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
238        was a minimum greater than 1 for a wide character in a possessive
239        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
240        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
241        character. Chaos in the form of incorrect output or a compiling loop could
242        result.
243    
244    9.  The restrictions on what a pattern can contain when partial matching is
245        requested for pcre_exec() have been removed. All patterns can now be
246        partially matched by this function. In addition, if there are at least two
247        slots in the offset vector, the offset of the earliest inspected character
248        for the match and the offset of the end of the subject are set in them when
249        PCRE_ERROR_PARTIAL is returned.
250    
251    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
252        synonymous with PCRE_PARTIAL, for backwards compatibility, and
253        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
254        and may be more useful for multi-segment matching.
255    
256    11. Partial matching with pcre_exec() is now more intuitive. A partial match
257        used to be given if ever the end of the subject was reached; now it is
258        given only if matching could not proceed because another character was
259        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
260        string "Z", which now yields "no match" instead of "partial match". In the
261        case of pcre_dfa_exec(), "no match" is given if every matching path for the
262        final character ended with (*FAIL).
263    
264    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
265        if the pattern had a "must contain" character that was already found in the
266        earlier partial match, unless partial matching was again requested. For
267        example, with the pattern /dog.(body)?/, the "must contain" character is
268        "g". If the first part-match was for the string "dog", restarting with
269        "sbody" failed. This bug has been fixed.
270    
271    13. The string returned by pcre_dfa_exec() after a partial match has been
272        changed so that it starts at the first inspected character rather than the
273        first character of the match. This makes a difference only if the pattern
274        starts with a lookbehind assertion or \b or \B (\K is not supported by
275        pcre_dfa_exec()). It's an incompatible change, but it makes the two
276        matching functions compatible, and I think it's the right thing to do.
277    
278    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
279        so that the demonstration program is easily available in environments where
280        PCRE has not been installed from source.
281    
282    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
283        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
284        library.
285    
286    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
287        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
288        is not the first non-POSIX option to be added. Clearly some people find
289        these options useful.
290    
291    17. If a caller to the POSIX matching function regexec() passes a non-zero
292        value for nmatch with a NULL value for pmatch, the value of
293        nmatch is forced to zero.
294    
295    18. RunGrepTest did not have a test for the availability of the -u option of
296        the diff command, as RunTest does. It now checks in the same way as
297        RunTest, and also checks for the -b option.
298    
299    19. If an odd number of negated classes containing just a single character
300        interposed, within parentheses, between a forward reference to a named
301        subpattern and the definition of the subpattern, compilation crashed with
302        an internal error, complaining that it could not find the referenced
303        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
304        [The bug was that it was starting one character too far in when skipping
305        over the character class, thus treating the ] as data rather than
306        terminating the class. This meant it could skip too much.]
307    
308    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
309        /g option in pcretest when the pattern contains \K, which makes it possible
310        to have an empty string match not at the start, even when the pattern is
311        anchored. Updated pcretest and pcredemo to use this option.
312    
313    21. If the maximum number of capturing subpatterns in a recursion was greater
314        than the maximum at the outer level, the higher number was returned, but
315        with unset values at the outer level. The correct (outer level) value is
316        now given.
317    
318    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
319        PCRE did not set those parentheses (unlike Perl). I have now found a way to
320        make it do so. The string so far is captured, making this feature
321        compatible with Perl.
322    
323    23. The tests have been re-organized, adding tests 11 and 12, to make it
324        possible to check the Perl 5.10 features against Perl 5.10.
325    
326    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
327        pattern matches a fixed length string. PCRE did not allow this; now it
328        does. Neither allows recursion.
329    
330    25. I finally figured out how to implement a request to provide the minimum
331        length of subject string that was needed in order to match a given pattern.
332        (It was back references and recursion that I had previously got hung up
333        on.) This code has now been added to pcre_study(); it finds a lower bound
334        to the length of subject needed. It is not necessarily the greatest lower
335        bound, but using it to avoid searching strings that are too short does give
336        some useful speed-ups. The value is available to calling programs via
337        pcre_fullinfo().
338    
339    26. While implementing 25, I discovered to my embarrassment that pcretest had
340        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
341        study optimizations had never been tested with that matching function.
342        Oops. What is worse, even when it was passed study data, there was a bug in
343        pcre_dfa_exec() that meant it never actually used it. Double oops. There
344        were also very few tests of studied patterns with pcre_dfa_exec().
345    
346    27. If (?| is used to create subpatterns with duplicate numbers, they are now
347        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
348        on the other side of the coin, they are no longer allowed to have different
349        names, because these cannot be distinguished in PCRE, and this has caused
350        confusion. (This is a difference from Perl.)
351    
352    28. When duplicate subpattern names are present (necessarily with different
353        numbers, as required by 27 above), and a test is made by name in a
354        conditional pattern, either for a subpattern having been matched, or for
355        recursion in such a pattern, all the associated numbered subpatterns are
356        tested, and the overall condition is true if the condition is true for any
357        one of them. This is the way Perl works, and is also more like the way
358        testing by number works.
359    
360    
361  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09
362  ---------------------  ---------------------
363    

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