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revision 195 by ph10, Mon Jul 30 13:23:28 2007 UTC revision 234 by ph10, Tue Sep 11 11:36:27 2007 UTC
# Line 1  Line 1 
1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 7.3 05-Jul-07  Version 7.4 10-Sep-07
5    ---------------------
6    
7    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
8        means that a class such as [\s] counted as "explicit reference to CR or
9        LF". That isn't really right - the whole point of the change was to try to
10        help when there was an actual mention of one of the two characters. So now
11        the change happens only if \r or \n (or a literal CR or LF) character is
12        encountered.
13    
14    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
15        of both had grown to the point where there were only 3 bits left.
16        Fortunately, there was spare space in the data structure, and so I have
17        moved the internal flags into a new 16-bit field to free up more option
18        bits.
19    
20    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
21        but did not set the internal JCHANGED flag - either of these is enough to
22        control the way the "get" function works - but the PCRE_INFO_JCHANGED
23        facility is supposed to tell if (?J) was ever used, so now (?J) at the
24        start sets both bits.
25    
26    4.  Added options (at build time, compile time, exec time) to change \R from
27        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
28    
29    5.  doc/pcresyntax.html was missing from the distribution.
30    
31    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
32        compatibility, even though it is no longer used.
33    
34    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
35        strtoull to pcrecpp.cc to select the available functions in WIN32 (where
36        different names are used).
37    
38    
39    Version 7.3 28-Aug-07
40  ---------------------  ---------------------
41    
42   1. In the rejigging of the build system that eventually resulted in 7.1, the   1. In the rejigging of the build system that eventually resulted in 7.1, the
# Line 9  Version 7.3 05-Jul-07 Line 44  Version 7.3 05-Jul-07
44      brackets there is not right, since it causes compilers to look for an      brackets there is not right, since it causes compilers to look for an
45      installed pcre.h, not the version that is in the source that is being      installed pcre.h, not the version that is in the source that is being
46      compiled (which of course may be different). I have changed it back to:      compiled (which of course may be different). I have changed it back to:
47    
48        #include "pcre.h"        #include "pcre.h"
49    
50      I have a vague recollection that the change was concerned with compiling in      I have a vague recollection that the change was concerned with compiling in
51      different directories, but in the new build system, that is taken care of      different directories, but in the new build system, that is taken care of
52      by the VPATH setting the Makefile.      by the VPATH setting the Makefile.
53    
54   2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed   2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
55      when the subject happened to end in the byte 0x85 (e.g. if the last      when the subject happened to end in the byte 0x85 (e.g. if the last
56      character was \x{1ec5}). *Character* 0x85 is one of the "any" newline      character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
# Line 23  Version 7.3 05-Jul-07 Line 58  Version 7.3 05-Jul-07
58      of another character. The bug was that, for an unlimited repeat of . in      of another character. The bug was that, for an unlimited repeat of . in
59      not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by      not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
60      characters when looking for a newline.      characters when looking for a newline.
   
  3. A small performance improvement in the DOTALL UTF-8 mode .* case.  
   
  4. Debugging: adjusted the names of opcodes for different kinds of parentheses  
     in debug output.  
   
  5. Arrange to use "%I64d" instead of "%lld" for long printing in the pcrecpp  
     unittest when running under MinGW.  
   
  6. ESC_K was left out of the EBCDIC table.  
61    
62     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
63    
64     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
65        in debug output.
66    
67     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
68        long printing in the pcrecpp unittest when running under MinGW.
69    
70     6. ESC_K was left out of the EBCDIC table.
71    
72     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
73        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
74        limit also applies to "virtual nesting" when a pattern is recursive, and in
75        this case 1000 isn't so big. I have been able to remove this limit at the
76        expense of backing off one optimization in certain circumstances. Normally,
77        when pcre_exec() would call its internal match() function recursively and
78        immediately return the result unconditionally, it uses a "tail recursion"
79        feature to save stack. However, when a subpattern that can match an empty
80        string has an unlimited repetition quantifier, it no longer makes this
81        optimization. That gives it a stack frame in which to save the data for
82        checking that an empty string has been matched. Previously this was taken
83        from the 1000-entry workspace that had been reserved. So now there is no
84        explicit limit, but more stack is used.
85    
86     8. Applied Daniel's patches to solve problems with the import/export magic
87        syntax that is required for Windows, and which was going wrong for the
88        pcreposix and pcrecpp parts of the library. These were overlooked when this
89        problem was solved for the main library.
90    
91     9. There were some crude static tests to avoid integer overflow when computing
92        the size of patterns that contain repeated groups with explicit upper
93        limits. As the maximum quantifier is 65535, the maximum group length was
94        set at 30,000 so that the product of these two numbers did not overflow a
95        32-bit integer. However, it turns out that people want to use groups that
96        are longer than 30,000 bytes (though not repeat them that many times).
97        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
98        made it possible to implement the integer overflow checks in a much more
99        dynamic way, which I have now done. The artificial limitation on group
100        length has been removed - we now have only the limit on the total length of
101        the compiled pattern, which depends on the LINK_SIZE setting.
102    
103    10. Fixed a bug in the documentation for get/copy named substring when
104        duplicate names are permitted. If none of the named substrings are set, the
105        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
106        empty string.
107    
108    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
109        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
110        because the ] is interpreted as the first data character and the
111        terminating ] is not found. PCRE has been made compatible with Perl in this
112        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
113        cause memory overwriting.
114    
115    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
116        string has been matched (to stop an infinite loop). It was not recognizing
117        a conditional subpattern that could match an empty string if that
118        subpattern was within another subpattern. For example, it looped when
119        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
120        condition was not nested. This bug has been fixed.
121    
122    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
123        past the start of the subject in the presence of bytes with the top bit
124        set, for example "\x8aBCD".
125    
126    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
127        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
128    
129    14. Optimized (?!) to (*FAIL).
130    
131    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
132        This restricts code points to be within the range 0 to 0x10FFFF, excluding
133        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
134        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
135        does: it's just the validity check that is more restrictive.
136    
137    16. Inserted checks for integer overflows during escape sequence (backslash)
138        processing, and also fixed erroneous offset values for syntax errors during
139        backslash processing.
140    
141    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
142        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
143    
144    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
145        caused an overrun.
146    
147    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
148        something other than just ASCII characters) inside a group that had an
149        unlimited repeat caused a loop at compile time (while checking to see
150        whether the group could match an empty string).
151    
152    20. Debugging a pattern containing \p or \P could cause a crash. For example,
153        [\P{Any}] did so. (Error in the code for printing property names.)
154    
155    21. An orphan \E inside a character class could cause a crash.
156    
157    22. A repeated capturing bracket such as (A)? could cause a wild memory
158        reference during compilation.
159    
160    23. There are several functions in pcre_compile() that scan along a compiled
161        expression for various reasons (e.g. to see if it's fixed length for look
162        behind). There were bugs in these functions when a repeated \p or \P was
163        present in the pattern. These operators have additional parameters compared
164        with \d, etc, and these were not being taken into account when moving along
165        the compiled data. Specifically:
166    
167        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
168            length.
169    
170        (b) An item such as \pL+ within a repeated group could cause crashes or
171            loops.
172    
173        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
174            "reference to non-existent subpattern" error.
175    
176        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
177    
178    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
179        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
180    
181    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
182    
183    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
184        character were causing crashes (broken optimization).
185    
186    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
187        \p or \P) caused a compile-time loop.
188    
189    28. More problems have arisen in unanchored patterns when CRLF is a valid line
190        break. For example, the unstudied pattern [\r\n]A does not match the string
191        "\r\nA" because change 7.0/46 below moves the current point on by two
192        characters after failing to match at the start. However, the pattern \nA
193        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
194        the same is true. There doesn't seem any very clean way out of this, but
195        what I have chosen to do makes the common cases work: PCRE now takes note
196        of whether there can be an explicit match for \r or \n anywhere in the
197        pattern, and if so, 7.0/46 no longer applies. As part of this change,
198        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
199        pattern has explicit CR or LF references.
200    
201    29. Added (*CR) etc for changing newline setting at start of pattern.
202    
203    
204  Version 7.2 19-Jun-07  Version 7.2 19-Jun-07

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