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revision 661 by ph10, Sun Aug 21 09:00:54 2011 UTC revision 749 by ph10, Fri Nov 18 10:36:45 2011 UTC
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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    
41    Version 8.20 21-Oct-2011
42    ------------------------
43    
44    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
45        a POSIX class. After further experiments with Perl, which convinced me that
46        Perl has bugs and confusions, a closing square bracket is no longer allowed
47        in a POSIX name. This bug also affected patterns with classes that started
48        with full stops.
49    
50    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
51        captured substring, but while checking the failing first alternative,
52        substring 1 is temporarily captured. If the output vector supplied to
53        pcre_exec() was not big enough for this capture, the yield of the function
54        was still zero ("insufficient space for captured substrings"). This cannot
55        be totally fixed without adding another stack variable, which seems a lot
56        of expense for a edge case. However, I have improved the situation in cases
57        such as /(a)(b)x|abc/ matched against "abc", where the return code
58        indicates that fewer than the maximum number of slots in the ovector have
59        been set.
60    
61    3.  Related to (2) above: when there are more back references in a pattern than
62        slots in the output vector, pcre_exec() uses temporary memory during
63        matching, and copies in the captures as far as possible afterwards. It was
64        using the entire output vector, but this conflicts with the specification
65        that only 2/3 is used for passing back captured substrings. Now it uses
66        only the first 2/3, for compatibility. This is, of course, another edge
67        case.
68    
69    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
70        main code base, and can be used by building with --enable-jit. When this is
71        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
72        runtime --no-jit option is given.
73    
74    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
75        ovector, the return from the function was zero, implying that there were
76        other matches that did not fit. The correct "exactly full" value is now
77        returned.
78    
79    6.  If a subpattern that was called recursively or as a subroutine contained
80        (*PRUNE) or any other control that caused it to give a non-standard return,
81        invalid errors such as "Error -26 (nested recursion at the same subject
82        position)" or even infinite loops could occur.
83    
84    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
85        computing the minimum length on reaching *ACCEPT, and so ended up with the
86        wrong value of 1 rather than 0. Further investigation indicates that
87        computing a minimum subject length in the presence of *ACCEPT is difficult
88        (think back references, subroutine calls), and so I have changed the code
89        so that no minimum is registered for a pattern that contains *ACCEPT.
90    
91    8.  If (*THEN) was present in the first (true) branch of a conditional group,
92        it was not handled as intended. [But see 16 below.]
93    
94    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
95        Sheri Pierce.
96    
97    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
98        the first byte in a match must be "a".
99    
100    11. Change 17 for 8.13 increased the recursion depth for patterns like
101        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
102        pattern contains any instances of (*THEN). If it does not, the old
103        optimizations are restored. It would be nice to do this on a per-group
104        basis, but at the moment that is not feasible.
105    
106    12. In some environments, the output of pcretest -C is CRLF terminated. This
107        broke RunTest's code that checks for the link size. A single white space
108        character after the value is now allowed for.
109    
110    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
111        For "fr", it uses the Windows-specific input and output files.
112    
113    14. If (*THEN) appeared in a group that was called recursively or as a
114        subroutine, it did not work as intended. [But see next item.]
115    
116    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
117        pattern fragments (but not containing any | characters). If A and B are
118        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
119        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
120        D. In other words, Perl considers parentheses that do not contain any |
121        characters to be part of a surrounding alternative, whereas PCRE was
122        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
123        differently. PCRE now behaves in the same way as Perl, except in the case
124        of subroutine/recursion calls such as (?1) which have in any case always
125        been different (but PCRE had them first :-).
126    
127    16. Related to 15 above: Perl does not treat the | in a conditional group as
128        creating alternatives. Such a group is treated in the same way as an
129        ordinary group without any | characters when processing (*THEN). PCRE has
130        been changed to match Perl's behaviour.
131    
132    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
133        RunGrepTest script failed.
134    
135    18. Change 22 for version 13 caused atomic groups to use more stack. This is
136        inevitable for groups that contain captures, but it can lead to a lot of
137        stack use in large patterns. The old behaviour has been restored for atomic
138        groups that do not contain any capturing parentheses.
139    
140    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
141        suppress the check for a minimum subject length at run time. (If it was
142        given to pcre_exec() or pcre_dfa_exec() it did work.)
143    
144    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
145        fail to work when decoding hex characters in data strings in EBCDIC
146        environments.
147    
148    21. It appears that in at least one Mac OS environment, the isxdigit() function
149        is implemented as a macro that evaluates to its argument more than once,
150        contravening the C 90 Standard (I haven't checked a later standard). There
151        was an instance in pcretest which caused it to go wrong when processing
152        \x{...} escapes in subject strings. The has been rewritten to avoid using
153        things like p++ in the argument of isxdigit().
154    
155    
156  Version 8.13 16-Aug-2011  Version 8.13 16-Aug-2011
# Line 107  Version 8.13 16-Aug-2011 Line 250  Version 8.13 16-Aug-2011
250      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
251      the possibility of (*THEN) occurring in these branches, tail recursion is      the possibility of (*THEN) occurring in these branches, tail recursion is
252      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
253      two optimizations have therefore been removed.      two optimizations have therefore been removed. [But see 8.20/11 above.]
254    
255  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
256      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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