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revision 672 by ph10, Tue Aug 23 16:45:55 2011 UTC revision 784 by ph10, Mon Dec 5 12:33:44 2011 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.20  Version 8.21 05-Dec-2011
5  ------------  ------------------------
6    
7    1.  Updating the JIT compiler.
8    
9    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
10        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    14. Perl does not support \N without a following name in a [] class; PCRE now
56        also gives an error.
57    
58    15. If a forward reference was repeated with an upper limit of around 2000,
59        it caused the error "internal error: overran compiling workspace". The
60        maximum number of forward references (including repeats) was limited by the
61        internal workspace, and dependent on the LINK_SIZE. The code has been
62        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
63        the default depends on LINK_SIZE. There is a new upper limit (for safety)
64        of around 200,000 forward references. While doing this, I also speeded up
65        the filling in of repeated forward references.
66    
67    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
68        incorrectly expecting the subject to contain another "a" after the start.
69    
70    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
71        in the match, the SKIP should be ignored. This was not happening; instead
72        the SKIP was being treated as NOMATCH. For patterns such as
73        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
74        tested.
75    
76    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
77        now much more compatible with Perl, in particular in cases where the result
78        is a non-match for a non-anchored pattern. For example, if
79        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
80        "m", where previously it did not return a name. A side effect of this
81        change is that for partial matches, the last encountered mark name is
82        returned, as for non matches. A number of tests that were previously not
83        Perl-compatible have been moved into the Perl-compatible test files. The
84        refactoring has had the pleasing side effect of removing one argument from
85        the match() function, thus reducing its stack requirements.
86    
87    19. If the /S+ option was used in pcretest to study a pattern using JIT,
88        subsequent uses of /S (without +) incorrectly behaved like /S+.
89    
90    21. Retrieve executable code size support for the JIT compiler and fixing
91        some warnings.
92    
93    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
94        not work when the shorter character appeared right at the end of the
95        subject string.
96    
97    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
98        systems.
99    
100    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
101        output it when the /M option is used in pcretest.
102    
103    25. The CheckMan script was not being included in the distribution. Also, added
104        an explicit "perl" to run Perl scripts from the PrepareRelease script
105        because this is reportedly needed in Windows.
106    
107    
108    Version 8.20 21-Oct-2011
109    ------------------------
110    
111    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
112        a POSIX class. After further experiments with Perl, which convinced me that
113        Perl has bugs and confusions, a closing square bracket is no longer allowed
114        in a POSIX name. This bug also affected patterns with classes that started
115        with full stops.
116    
117    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
118        captured substring, but while checking the failing first alternative,
119        substring 1 is temporarily captured. If the output vector supplied to
120        pcre_exec() was not big enough for this capture, the yield of the function
121        was still zero ("insufficient space for captured substrings"). This cannot
122        be totally fixed without adding another stack variable, which seems a lot
123        of expense for a edge case. However, I have improved the situation in cases
124        such as /(a)(b)x|abc/ matched against "abc", where the return code
125        indicates that fewer than the maximum number of slots in the ovector have
126        been set.
127    
128    3.  Related to (2) above: when there are more back references in a pattern than
129        slots in the output vector, pcre_exec() uses temporary memory during
130        matching, and copies in the captures as far as possible afterwards. It was
131        using the entire output vector, but this conflicts with the specification
132        that only 2/3 is used for passing back captured substrings. Now it uses
133        only the first 2/3, for compatibility. This is, of course, another edge
134        case.
135    
136  1. Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had  4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
137     a POSIX class. After further experiments with Perl, which convinced me that      main code base, and can be used by building with --enable-jit. When this is
138     Perl has bugs and confusions, a closing square bracket is no longer allowed      done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
139     in a POSIX name.      runtime --no-jit option is given.
140    
141  2. If a pattern such as /(a)b|ac/ is matched against "ac", there is no captured  5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
142     substring, but while checking the failing first alternative, substring 1 is      ovector, the return from the function was zero, implying that there were
143     temporarily captured. If the output vector supplied to pcre_exec() was not      other matches that did not fit. The correct "exactly full" value is now
144     big enough for this capture, the yield of the function was still zero      returned.
145     ("insufficient space for captured substrings"). This cannot be totally fixed  
146     without adding another stack variable, which seems a lot of expense for a  6.  If a subpattern that was called recursively or as a subroutine contained
147     edge case. However, I have improved the situation in cases such as      (*PRUNE) or any other control that caused it to give a non-standard return,
148     /(a)(b)x|abc/ matched against "abc", where the return code indicates that      invalid errors such as "Error -26 (nested recursion at the same subject
149     fewer than the maximum number of slots in the ovector have been set.      position)" or even infinite loops could occur.
150    
151  3. Related to (2) above: when there are more back references in a pattern than  7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
152     slots in the output vector, pcre_exec() uses temporary memory during      computing the minimum length on reaching *ACCEPT, and so ended up with the
153     matching, and copies in the captures as far as possible afterwards. It was      wrong value of 1 rather than 0. Further investigation indicates that
154     using the entire output vector, but this conflicts with the specification      computing a minimum subject length in the presence of *ACCEPT is difficult
155     that only 2/3 is used for passing back captured substrings. Now it uses only      (think back references, subroutine calls), and so I have changed the code
156     the first 2/3, for compatibility. This is, of course, another edge case.      so that no minimum is registered for a pattern that contains *ACCEPT.
157    
158  4. Zoltan Herczeg's just-in-time compiler support has been integrated into the  8.  If (*THEN) was present in the first (true) branch of a conditional group,
159     main code base, and can be used by building with --enable-jit.      it was not handled as intended. [But see 16 below.]
160    
161    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
162        Sheri Pierce.
163    
164    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
165        the first byte in a match must be "a".
166    
167    11. Change 17 for 8.13 increased the recursion depth for patterns like
168        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
169        pattern contains any instances of (*THEN). If it does not, the old
170        optimizations are restored. It would be nice to do this on a per-group
171        basis, but at the moment that is not feasible.
172    
173    12. In some environments, the output of pcretest -C is CRLF terminated. This
174        broke RunTest's code that checks for the link size. A single white space
175        character after the value is now allowed for.
176    
177    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
178        For "fr", it uses the Windows-specific input and output files.
179    
180    14. If (*THEN) appeared in a group that was called recursively or as a
181        subroutine, it did not work as intended. [But see next item.]
182    
183    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
184        pattern fragments (but not containing any | characters). If A and B are
185        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
186        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
187        D. In other words, Perl considers parentheses that do not contain any |
188        characters to be part of a surrounding alternative, whereas PCRE was
189        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
190        differently. PCRE now behaves in the same way as Perl, except in the case
191        of subroutine/recursion calls such as (?1) which have in any case always
192        been different (but PCRE had them first :-).
193    
194    16. Related to 15 above: Perl does not treat the | in a conditional group as
195        creating alternatives. Such a group is treated in the same way as an
196        ordinary group without any | characters when processing (*THEN). PCRE has
197        been changed to match Perl's behaviour.
198    
199    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
200        RunGrepTest script failed.
201    
202    18. Change 22 for version 13 caused atomic groups to use more stack. This is
203        inevitable for groups that contain captures, but it can lead to a lot of
204        stack use in large patterns. The old behaviour has been restored for atomic
205        groups that do not contain any capturing parentheses.
206    
207    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
208        suppress the check for a minimum subject length at run time. (If it was
209        given to pcre_exec() or pcre_dfa_exec() it did work.)
210    
211    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
212        fail to work when decoding hex characters in data strings in EBCDIC
213        environments.
214    
215    21. It appears that in at least one Mac OS environment, the isxdigit() function
216        is implemented as a macro that evaluates to its argument more than once,
217        contravening the C 90 Standard (I haven't checked a later standard). There
218        was an instance in pcretest which caused it to go wrong when processing
219        \x{...} escapes in subject strings. The has been rewritten to avoid using
220        things like p++ in the argument of isxdigit().
221    
222    
223  Version 8.13 16-Aug-2011  Version 8.13 16-Aug-2011
# Line 127  Version 8.13 16-Aug-2011 Line 317  Version 8.13 16-Aug-2011
317      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
318      the possibility of (*THEN) occurring in these branches, tail recursion is      the possibility of (*THEN) occurring in these branches, tail recursion is
319      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
320      two optimizations have therefore been removed.      two optimizations have therefore been removed. [But see 8.20/11 above.]
321    
322  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
323      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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