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revision 681 by ph10, Tue Sep 6 09:16:32 2011 UTC revision 747 by ph10, Tue Nov 15 17:35:10 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  2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
10     in a POSIX name.      are added as well.
11    
12  2. If a pattern such as /(a)b|ac/ is matched against "ac", there is no captured  3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
13     substring, but while checking the failing first alternative, substring 1 is      PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
14     temporarily captured. If the output vector supplied to pcre_exec() was not      calling _pcre_jit_exec. Some extra comments are added.
15     big enough for this capture, the yield of the function was still zero  
16     ("insufficient space for captured substrings"). This cannot be totally fixed  4.  Mark settings inside atomic groups that do not contain any capturing
17     without adding another stack variable, which seems a lot of expense for a      parentheses, for example, (?>a(*:m)), were not being passed out. This bug
18     edge case. However, I have improved the situation in cases such as      was introduced by change 18 for 8.20.
19     /(a)(b)x|abc/ matched against "abc", where the return code indicates that  
20     fewer than the maximum number of slots in the ovector have been set.  5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
21        ECMA-262 standard.
22  3. Related to (2) above: when there are more back references in a pattern than  
23     slots in the output vector, pcre_exec() uses temporary memory during  6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
24     matching, and copies in the captures as far as possible afterwards. It was      erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
25     using the entire output vector, but this conflicts with the specification      This bug was probably introduced by change 9 of 8.13.
26     that only 2/3 is used for passing back captured substrings. Now it uses only  
27     the first 2/3, for compatibility. This is, of course, another edge case.  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  4. Zoltan Herczeg's just-in-time compiler support has been integrated into the      opcodes had not been added to the fixed-length checking code. I have (a)
30     main code base, and can be used by building with --enable-jit.      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  5. When the number of matches in a pcre_dfa_exec() run exactly filled the      length instead of just assuming "not fixed length". The items that were
33     ovector, the return from the function was zero, implying that there were      rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
34     other matches that did not fit. The correct "exactly full" value is now      (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
35     returned.      repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
36    
37  6. If a subpattern that was called recursively or as a subroutine contained  
38     (*PRUNE) or any other control that caused it to give a non-standard return,  Version 8.20 21-Oct-2011
39     invalid errors such as "Error -26 (nested recursion at the same subject  ------------------------
40     position)" or even infinite loops could occur.  
41    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
42        a POSIX class. After further experiments with Perl, which convinced me that
43        Perl has bugs and confusions, a closing square bracket is no longer allowed
44        in a POSIX name. This bug also affected patterns with classes that started
45        with full stops.
46    
47    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
48        captured substring, but while checking the failing first alternative,
49        substring 1 is temporarily captured. If the output vector supplied to
50        pcre_exec() was not big enough for this capture, the yield of the function
51        was still zero ("insufficient space for captured substrings"). This cannot
52        be totally fixed without adding another stack variable, which seems a lot
53        of expense for a edge case. However, I have improved the situation in cases
54        such as /(a)(b)x|abc/ matched against "abc", where the return code
55        indicates that fewer than the maximum number of slots in the ovector have
56        been set.
57    
58    3.  Related to (2) above: when there are more back references in a pattern than
59        slots in the output vector, pcre_exec() uses temporary memory during
60        matching, and copies in the captures as far as possible afterwards. It was
61        using the entire output vector, but this conflicts with the specification
62        that only 2/3 is used for passing back captured substrings. Now it uses
63        only the first 2/3, for compatibility. This is, of course, another edge
64        case.
65    
66    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
67        main code base, and can be used by building with --enable-jit. When this is
68        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
69        runtime --no-jit option is given.
70    
71    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
72        ovector, the return from the function was zero, implying that there were
73        other matches that did not fit. The correct "exactly full" value is now
74        returned.
75    
76    6.  If a subpattern that was called recursively or as a subroutine contained
77        (*PRUNE) or any other control that caused it to give a non-standard return,
78        invalid errors such as "Error -26 (nested recursion at the same subject
79        position)" or even infinite loops could occur.
80    
81    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
82        computing the minimum length on reaching *ACCEPT, and so ended up with the
83        wrong value of 1 rather than 0. Further investigation indicates that
84        computing a minimum subject length in the presence of *ACCEPT is difficult
85        (think back references, subroutine calls), and so I have changed the code
86        so that no minimum is registered for a pattern that contains *ACCEPT.
87    
88    8.  If (*THEN) was present in the first (true) branch of a conditional group,
89        it was not handled as intended. [But see 16 below.]
90    
91    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
92        Sheri Pierce.
93    
94    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
95        the first byte in a match must be "a".
96    
97    11. Change 17 for 8.13 increased the recursion depth for patterns like
98        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
99        pattern contains any instances of (*THEN). If it does not, the old
100        optimizations are restored. It would be nice to do this on a per-group
101        basis, but at the moment that is not feasible.
102    
103    12. In some environments, the output of pcretest -C is CRLF terminated. This
104        broke RunTest's code that checks for the link size. A single white space
105        character after the value is now allowed for.
106    
107    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
108        For "fr", it uses the Windows-specific input and output files.
109    
110    14. If (*THEN) appeared in a group that was called recursively or as a
111        subroutine, it did not work as intended. [But see next item.]
112    
113    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
114        pattern fragments (but not containing any | characters). If A and B are
115        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
116        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
117        D. In other words, Perl considers parentheses that do not contain any |
118        characters to be part of a surrounding alternative, whereas PCRE was
119        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
120        differently. PCRE now behaves in the same way as Perl, except in the case
121        of subroutine/recursion calls such as (?1) which have in any case always
122        been different (but PCRE had them first :-).
123    
124    16. Related to 15 above: Perl does not treat the | in a conditional group as
125        creating alternatives. Such a group is treated in the same way as an
126        ordinary group without any | characters when processing (*THEN). PCRE has
127        been changed to match Perl's behaviour.
128    
129    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
130        RunGrepTest script failed.
131    
132    18. Change 22 for version 13 caused atomic groups to use more stack. This is
133        inevitable for groups that contain captures, but it can lead to a lot of
134        stack use in large patterns. The old behaviour has been restored for atomic
135        groups that do not contain any capturing parentheses.
136    
137    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
138        suppress the check for a minimum subject length at run time. (If it was
139        given to pcre_exec() or pcre_dfa_exec() it did work.)
140    
141    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
142        fail to work when decoding hex characters in data strings in EBCDIC
143        environments.
144    
145    21. It appears that in at least one Mac OS environment, the isxdigit() function
146        is implemented as a macro that evaluates to its argument more than once,
147        contravening the C 90 Standard (I haven't checked a later standard). There
148        was an instance in pcretest which caused it to go wrong when processing
149        \x{...} escapes in subject strings. The has been rewritten to avoid using
150        things like p++ in the argument of isxdigit().
151    
152    
153  Version 8.13 16-Aug-2011  Version 8.13 16-Aug-2011
# Line 137  Version 8.13 16-Aug-2011 Line 247  Version 8.13 16-Aug-2011
247      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
248      the possibility of (*THEN) occurring in these branches, tail recursion is      the possibility of (*THEN) occurring in these branches, tail recursion is
249      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
250      two optimizations have therefore been removed.      two optimizations have therefore been removed. [But see 8.20/11 above.]
251    
252  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
253      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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