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revision 661 by ph10, Sun Aug 21 09:00:54 2011 UTC revision 754 by ph10, Sat Nov 19 18:32:18 2011 UTC
# Line 1  Line 1 
1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.20  Version 8.21
5  ------------  ------------
6    
7  1. Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had  1.  Updating the JIT compiler.
8  a POSIX class. After further experiments with Perl, which convinced me that  
9  Perl has bugs and confusions, a closing square bracket is no longer allowed in  2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
10  a POSIX name.      are added as well.
11    
12    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
13        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
14        calling _pcre_jit_exec. Some extra comments are added.
15    
16    4.  Mark settings inside atomic groups that do not contain any capturing
17        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
18        was introduced by change 18 for 8.20.
19    
20    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
21        ECMA-262 standard.
22    
23    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
24        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
25        This bug was probably introduced by change 9 of 8.13.
26    
27    7.  While fixing 6 above, I noticed that a number of other items were being
28        incorrectly rejected as "not fixed length". This arose partly because newer
29        opcodes had not been added to the fixed-length checking code. I have (a)
30        corrected the bug and added tests for these items, and (b) arranged for an
31        error to occur if an unknown opcode is encountered while checking for fixed
32        length instead of just assuming "not fixed length". The items that were
33        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
34        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
35        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
36    
37    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
38        being incorrectly compiled and would have given unpredicatble results.
39    
40    9.  A possessively repeated subpattern with minimum repeat count greater than
41        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
42        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
43        the first (A) could occur when it should not.
44    
45    10. Add a cast and remove a redundant test from the code.
46    
47    11. JIT should use pcre_malloc/pcre_free for allocation.
48    
49    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
50        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
51        is anything other than /usr, -L is still shown).
52    
53    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
54    
55    
56    Version 8.20 21-Oct-2011
57    ------------------------
58    
59    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
60        a POSIX class. After further experiments with Perl, which convinced me that
61        Perl has bugs and confusions, a closing square bracket is no longer allowed
62        in a POSIX name. This bug also affected patterns with classes that started
63        with full stops.
64    
65    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
66        captured substring, but while checking the failing first alternative,
67        substring 1 is temporarily captured. If the output vector supplied to
68        pcre_exec() was not big enough for this capture, the yield of the function
69        was still zero ("insufficient space for captured substrings"). This cannot
70        be totally fixed without adding another stack variable, which seems a lot
71        of expense for a edge case. However, I have improved the situation in cases
72        such as /(a)(b)x|abc/ matched against "abc", where the return code
73        indicates that fewer than the maximum number of slots in the ovector have
74        been set.
75    
76    3.  Related to (2) above: when there are more back references in a pattern than
77        slots in the output vector, pcre_exec() uses temporary memory during
78        matching, and copies in the captures as far as possible afterwards. It was
79        using the entire output vector, but this conflicts with the specification
80        that only 2/3 is used for passing back captured substrings. Now it uses
81        only the first 2/3, for compatibility. This is, of course, another edge
82        case.
83    
84    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
85        main code base, and can be used by building with --enable-jit. When this is
86        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
87        runtime --no-jit option is given.
88    
89    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
90        ovector, the return from the function was zero, implying that there were
91        other matches that did not fit. The correct "exactly full" value is now
92        returned.
93    
94    6.  If a subpattern that was called recursively or as a subroutine contained
95        (*PRUNE) or any other control that caused it to give a non-standard return,
96        invalid errors such as "Error -26 (nested recursion at the same subject
97        position)" or even infinite loops could occur.
98    
99    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
100        computing the minimum length on reaching *ACCEPT, and so ended up with the
101        wrong value of 1 rather than 0. Further investigation indicates that
102        computing a minimum subject length in the presence of *ACCEPT is difficult
103        (think back references, subroutine calls), and so I have changed the code
104        so that no minimum is registered for a pattern that contains *ACCEPT.
105    
106    8.  If (*THEN) was present in the first (true) branch of a conditional group,
107        it was not handled as intended. [But see 16 below.]
108    
109    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
110        Sheri Pierce.
111    
112    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
113        the first byte in a match must be "a".
114    
115    11. Change 17 for 8.13 increased the recursion depth for patterns like
116        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
117        pattern contains any instances of (*THEN). If it does not, the old
118        optimizations are restored. It would be nice to do this on a per-group
119        basis, but at the moment that is not feasible.
120    
121    12. In some environments, the output of pcretest -C is CRLF terminated. This
122        broke RunTest's code that checks for the link size. A single white space
123        character after the value is now allowed for.
124    
125    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
126        For "fr", it uses the Windows-specific input and output files.
127    
128    14. If (*THEN) appeared in a group that was called recursively or as a
129        subroutine, it did not work as intended. [But see next item.]
130    
131    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
132        pattern fragments (but not containing any | characters). If A and B are
133        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
134        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
135        D. In other words, Perl considers parentheses that do not contain any |
136        characters to be part of a surrounding alternative, whereas PCRE was
137        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
138        differently. PCRE now behaves in the same way as Perl, except in the case
139        of subroutine/recursion calls such as (?1) which have in any case always
140        been different (but PCRE had them first :-).
141    
142    16. Related to 15 above: Perl does not treat the | in a conditional group as
143        creating alternatives. Such a group is treated in the same way as an
144        ordinary group without any | characters when processing (*THEN). PCRE has
145        been changed to match Perl's behaviour.
146    
147    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
148        RunGrepTest script failed.
149    
150    18. Change 22 for version 13 caused atomic groups to use more stack. This is
151        inevitable for groups that contain captures, but it can lead to a lot of
152        stack use in large patterns. The old behaviour has been restored for atomic
153        groups that do not contain any capturing parentheses.
154    
155    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
156        suppress the check for a minimum subject length at run time. (If it was
157        given to pcre_exec() or pcre_dfa_exec() it did work.)
158    
159    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
160        fail to work when decoding hex characters in data strings in EBCDIC
161        environments.
162    
163    21. It appears that in at least one Mac OS environment, the isxdigit() function
164        is implemented as a macro that evaluates to its argument more than once,
165        contravening the C 90 Standard (I haven't checked a later standard). There
166        was an instance in pcretest which caused it to go wrong when processing
167        \x{...} escapes in subject strings. The has been rewritten to avoid using
168        things like p++ in the argument of isxdigit().
169    
170    
171  Version 8.13 16-Aug-2011  Version 8.13 16-Aug-2011
# Line 107  Version 8.13 16-Aug-2011 Line 265  Version 8.13 16-Aug-2011
265      tail recursion to cut down on stack usage. Unfortunately, now that there is      tail recursion to cut down on stack usage. Unfortunately, now that there is
266      the possibility of (*THEN) occurring in these branches, tail recursion is      the possibility of (*THEN) occurring in these branches, tail recursion is
267      no longer possible because the return has to be checked for (*THEN). These      no longer possible because the return has to be checked for (*THEN). These
268      two optimizations have therefore been removed.      two optimizations have therefore been removed. [But see 8.20/11 above.]
269    
270  18. If a pattern containing \R was studied, it was assumed that \R always  18. If a pattern containing \R was studied, it was assumed that \R always
271      matched two bytes, thus causing the minimum subject length to be      matched two bytes, thus causing the minimum subject length to be

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