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revision 672 by ph10, Tue Aug 23 16:45:55 2011 UTC revision 752 by zherczeg, Sat Nov 19 15:28:29 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  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        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    
50    Version 8.20 21-Oct-2011
51    ------------------------
52    
53    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
54        a POSIX class. After further experiments with Perl, which convinced me that
55        Perl has bugs and confusions, a closing square bracket is no longer allowed
56        in a POSIX name. This bug also affected patterns with classes that started
57        with full stops.
58    
59    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
60        captured substring, but while checking the failing first alternative,
61        substring 1 is temporarily captured. If the output vector supplied to
62        pcre_exec() was not big enough for this capture, the yield of the function
63        was still zero ("insufficient space for captured substrings"). This cannot
64        be totally fixed without adding another stack variable, which seems a lot
65        of expense for a edge case. However, I have improved the situation in cases
66        such as /(a)(b)x|abc/ matched against "abc", where the return code
67        indicates that fewer than the maximum number of slots in the ovector have
68        been set.
69    
70    3.  Related to (2) above: when there are more back references in a pattern than
71        slots in the output vector, pcre_exec() uses temporary memory during
72        matching, and copies in the captures as far as possible afterwards. It was
73        using the entire output vector, but this conflicts with the specification
74        that only 2/3 is used for passing back captured substrings. Now it uses
75        only the first 2/3, for compatibility. This is, of course, another edge
76        case.
77    
78    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
79        main code base, and can be used by building with --enable-jit. When this is
80        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
81        runtime --no-jit option is given.
82    
83    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
84        ovector, the return from the function was zero, implying that there were
85        other matches that did not fit. The correct "exactly full" value is now
86        returned.
87    
88    6.  If a subpattern that was called recursively or as a subroutine contained
89        (*PRUNE) or any other control that caused it to give a non-standard return,
90        invalid errors such as "Error -26 (nested recursion at the same subject
91        position)" or even infinite loops could occur.
92    
93    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
94        computing the minimum length on reaching *ACCEPT, and so ended up with the
95        wrong value of 1 rather than 0. Further investigation indicates that
96        computing a minimum subject length in the presence of *ACCEPT is difficult
97        (think back references, subroutine calls), and so I have changed the code
98        so that no minimum is registered for a pattern that contains *ACCEPT.
99    
100    8.  If (*THEN) was present in the first (true) branch of a conditional group,
101        it was not handled as intended. [But see 16 below.]
102    
103    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
104        Sheri Pierce.
105    
106    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
107        the first byte in a match must be "a".
108    
109    11. Change 17 for 8.13 increased the recursion depth for patterns like
110        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
111        pattern contains any instances of (*THEN). If it does not, the old
112        optimizations are restored. It would be nice to do this on a per-group
113        basis, but at the moment that is not feasible.
114    
115    12. In some environments, the output of pcretest -C is CRLF terminated. This
116        broke RunTest's code that checks for the link size. A single white space
117        character after the value is now allowed for.
118    
119    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
120        For "fr", it uses the Windows-specific input and output files.
121    
122    14. If (*THEN) appeared in a group that was called recursively or as a
123        subroutine, it did not work as intended. [But see next item.]
124    
125    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
126        pattern fragments (but not containing any | characters). If A and B are
127        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
128        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
129        D. In other words, Perl considers parentheses that do not contain any |
130        characters to be part of a surrounding alternative, whereas PCRE was
131        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
132        differently. PCRE now behaves in the same way as Perl, except in the case
133        of subroutine/recursion calls such as (?1) which have in any case always
134        been different (but PCRE had them first :-).
135    
136    16. Related to 15 above: Perl does not treat the | in a conditional group as
137        creating alternatives. Such a group is treated in the same way as an
138        ordinary group without any | characters when processing (*THEN). PCRE has
139        been changed to match Perl's behaviour.
140    
141    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
142        RunGrepTest script failed.
143    
144    18. Change 22 for version 13 caused atomic groups to use more stack. This is
145        inevitable for groups that contain captures, but it can lead to a lot of
146        stack use in large patterns. The old behaviour has been restored for atomic
147        groups that do not contain any capturing parentheses.
148    
149    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
150        suppress the check for a minimum subject length at run time. (If it was
151        given to pcre_exec() or pcre_dfa_exec() it did work.)
152    
153    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
154        fail to work when decoding hex characters in data strings in EBCDIC
155        environments.
156    
157    21. It appears that in at least one Mac OS environment, the isxdigit() function
158        is implemented as a macro that evaluates to its argument more than once,
159        contravening the C 90 Standard (I haven't checked a later standard). There
160        was an instance in pcretest which caused it to go wrong when processing
161        \x{...} escapes in subject strings. The has been rewritten to avoid using
162        things like p++ in the argument of isxdigit().
163    
164    
165  Version 8.13 16-Aug-2011  Version 8.13 16-Aug-2011
# Line 127  Version 8.13 16-Aug-2011 Line 259  Version 8.13 16-Aug-2011
259      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
260      the possibility of (*THEN) occurring in these branches, tail recursion is      the possibility of (*THEN) occurring in these branches, tail recursion is
261      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
262      two optimizations have therefore been removed.      two optimizations have therefore been removed. [But see 8.20/11 above.]
263    
264  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
265      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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