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revision 691 by ph10, Sun Sep 11 14:31:21 2011 UTC revision 792 by ph10, Wed Dec 7 16:44:48 2011 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.20 12-Sep-2011  Version 8.21 05-Dec-2011
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. This bug also affected patterns with classes that started      are added as well.
11     with full stops.  
12    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
13  2. If a pattern such as /(a)b|ac/ is matched against "ac", there is no captured      PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
14     substring, but while checking the failing first alternative, substring 1 is      calling _pcre_jit_exec. Some extra comments are added.
15     temporarily captured. If the output vector supplied to pcre_exec() was not  
16     big enough for this capture, the yield of the function was still zero  4.  (*MARK) settings inside atomic groups that do not contain any capturing
17     ("insufficient space for captured substrings"). This cannot be totally fixed      parentheses, for example, (?>a(*:m)), were not being passed out. This bug
18     without adding another stack variable, which seems a lot of expense for a      was introduced by change 18 for 8.20.
19     edge case. However, I have improved the situation in cases such as  
20     /(a)(b)x|abc/ matched against "abc", where the return code indicates that  5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
21     fewer than the maximum number of slots in the ovector have been set.      ECMA-262 standard.
22    
23  3. Related to (2) above: when there are more back references in a pattern than  6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
24     slots in the output vector, pcre_exec() uses temporary memory during      erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
25     matching, and copies in the captures as far as possible afterwards. It was      This bug was probably introduced by change 9 of 8.13.
26     using the entire output vector, but this conflicts with the specification  
27     that only 2/3 is used for passing back captured substrings. Now it uses only  7.  While fixing 6 above, I noticed that a number of other items were being
28     the first 2/3, for compatibility. This is, of course, another edge case.      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  4. Zoltan Herczeg's just-in-time compiler support has been integrated into the      corrected the bug and added tests for these items, and (b) arranged for an
31     main code base, and can be used by building with --enable-jit. When this is      error to occur if an unknown opcode is encountered while checking for fixed
32     done, pcregrep automatically uses it unless --disable-pcregrep-jit or the      length instead of just assuming "not fixed length". The items that were
33     runtime --no-jit option is given.      rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
34        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
35  5. When the number of matches in a pcre_dfa_exec() run exactly filled the      repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
36     ovector, the return from the function was zero, implying that there were  
37     other matches that did not fit. The correct "exactly full" value is now  8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
38     returned.      being incorrectly compiled and would have given unpredicatble results.
39    
40  6. If a subpattern that was called recursively or as a subroutine contained  9.  A possessively repeated subpattern with minimum repeat count greater than
41     (*PRUNE) or any other control that caused it to give a non-standard return,      one behaved incorrectly. For example, (A){2,}+ behaved as if it was
42     invalid errors such as "Error -26 (nested recursion at the same subject      (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
43     position)" or even infinite loops could occur.      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    26. If study data was being save in a file and studying had not found a set of
108        "starts with" bytes for the pattern, the data written to the file (though
109        never used) was taken from uninitialized memory and so caused valgrind to
110        complain.
111    
112    27. Updated RunTest.bat as provided by Sheri Pierce.
113    
114    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
115    
116    
117    Version 8.20 21-Oct-2011
118    ------------------------
119    
120    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
121        a POSIX class. After further experiments with Perl, which convinced me that
122        Perl has bugs and confusions, a closing square bracket is no longer allowed
123        in a POSIX name. This bug also affected patterns with classes that started
124        with full stops.
125    
126    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
127        captured substring, but while checking the failing first alternative,
128        substring 1 is temporarily captured. If the output vector supplied to
129        pcre_exec() was not big enough for this capture, the yield of the function
130        was still zero ("insufficient space for captured substrings"). This cannot
131        be totally fixed without adding another stack variable, which seems a lot
132        of expense for a edge case. However, I have improved the situation in cases
133        such as /(a)(b)x|abc/ matched against "abc", where the return code
134        indicates that fewer than the maximum number of slots in the ovector have
135        been set.
136    
137    3.  Related to (2) above: when there are more back references in a pattern than
138        slots in the output vector, pcre_exec() uses temporary memory during
139        matching, and copies in the captures as far as possible afterwards. It was
140        using the entire output vector, but this conflicts with the specification
141        that only 2/3 is used for passing back captured substrings. Now it uses
142        only the first 2/3, for compatibility. This is, of course, another edge
143        case.
144    
145    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
146        main code base, and can be used by building with --enable-jit. When this is
147        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
148        runtime --no-jit option is given.
149    
150    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
151        ovector, the return from the function was zero, implying that there were
152        other matches that did not fit. The correct "exactly full" value is now
153        returned.
154    
155    6.  If a subpattern that was called recursively or as a subroutine contained
156        (*PRUNE) or any other control that caused it to give a non-standard return,
157        invalid errors such as "Error -26 (nested recursion at the same subject
158        position)" or even infinite loops could occur.
159    
160    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
161        computing the minimum length on reaching *ACCEPT, and so ended up with the
162        wrong value of 1 rather than 0. Further investigation indicates that
163        computing a minimum subject length in the presence of *ACCEPT is difficult
164        (think back references, subroutine calls), and so I have changed the code
165        so that no minimum is registered for a pattern that contains *ACCEPT.
166    
167    8.  If (*THEN) was present in the first (true) branch of a conditional group,
168        it was not handled as intended. [But see 16 below.]
169    
170    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
171        Sheri Pierce.
172    
173    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
174        the first byte in a match must be "a".
175    
176    11. Change 17 for 8.13 increased the recursion depth for patterns like
177        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
178        pattern contains any instances of (*THEN). If it does not, the old
179        optimizations are restored. It would be nice to do this on a per-group
180        basis, but at the moment that is not feasible.
181    
182    12. In some environments, the output of pcretest -C is CRLF terminated. This
183        broke RunTest's code that checks for the link size. A single white space
184        character after the value is now allowed for.
185    
186    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
187        For "fr", it uses the Windows-specific input and output files.
188    
189    14. If (*THEN) appeared in a group that was called recursively or as a
190        subroutine, it did not work as intended. [But see next item.]
191    
192    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
193        pattern fragments (but not containing any | characters). If A and B are
194        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
195        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
196        D. In other words, Perl considers parentheses that do not contain any |
197        characters to be part of a surrounding alternative, whereas PCRE was
198        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
199        differently. PCRE now behaves in the same way as Perl, except in the case
200        of subroutine/recursion calls such as (?1) which have in any case always
201        been different (but PCRE had them first :-).
202    
203    16. Related to 15 above: Perl does not treat the | in a conditional group as
204        creating alternatives. Such a group is treated in the same way as an
205        ordinary group without any | characters when processing (*THEN). PCRE has
206        been changed to match Perl's behaviour.
207    
208    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
209        RunGrepTest script failed.
210    
211    18. Change 22 for version 13 caused atomic groups to use more stack. This is
212        inevitable for groups that contain captures, but it can lead to a lot of
213        stack use in large patterns. The old behaviour has been restored for atomic
214        groups that do not contain any capturing parentheses.
215    
216    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
217        suppress the check for a minimum subject length at run time. (If it was
218        given to pcre_exec() or pcre_dfa_exec() it did work.)
219    
220    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
221        fail to work when decoding hex characters in data strings in EBCDIC
222        environments.
223    
224    21. It appears that in at least one Mac OS environment, the isxdigit() function
225        is implemented as a macro that evaluates to its argument more than once,
226        contravening the C 90 Standard (I haven't checked a later standard). There
227        was an instance in pcretest which caused it to go wrong when processing
228        \x{...} escapes in subject strings. The has been rewritten to avoid using
229        things like p++ in the argument of isxdigit().
230    
231    
232  Version 8.13 16-Aug-2011  Version 8.13 16-Aug-2011
# Line 140  Version 8.13 16-Aug-2011 Line 326  Version 8.13 16-Aug-2011
326      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
327      the possibility of (*THEN) occurring in these branches, tail recursion is      the possibility of (*THEN) occurring in these branches, tail recursion is
328      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
329      two optimizations have therefore been removed.      two optimizations have therefore been removed. [But see 8.20/11 above.]
330    
331  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
332      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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