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revision 168 by ph10, Tue May 29 15:18:18 2007 UTC revision 239 by ph10, Tue Sep 11 13:46:30 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 7.2 01-May-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    8.  Changed all #include <config.h> to #include "config.h". There were also
39        some further <pcre.h> cases that I changed to "pcre.h".
40    
41    9.  When pcregrep was used with the --colour option, it missed the line ending
42        sequence off the lines that it output.
43    
44    
45    Version 7.3 28-Aug-07
46    ---------------------
47    
48     1. In the rejigging of the build system that eventually resulted in 7.1, the
49        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
50        brackets there is not right, since it causes compilers to look for an
51        installed pcre.h, not the version that is in the source that is being
52        compiled (which of course may be different). I have changed it back to:
53    
54          #include "pcre.h"
55    
56        I have a vague recollection that the change was concerned with compiling in
57        different directories, but in the new build system, that is taken care of
58        by the VPATH setting the Makefile.
59    
60     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
61        when the subject happened to end in the byte 0x85 (e.g. if the last
62        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
63        characters but of course it shouldn't be taken as a newline when it is part
64        of another character. The bug was that, for an unlimited repeat of . in
65        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
66        characters when looking for a newline.
67    
68     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
69    
70     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
71        in debug output.
72    
73     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
74        long printing in the pcrecpp unittest when running under MinGW.
75    
76     6. ESC_K was left out of the EBCDIC table.
77    
78     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
79        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
80        limit also applies to "virtual nesting" when a pattern is recursive, and in
81        this case 1000 isn't so big. I have been able to remove this limit at the
82        expense of backing off one optimization in certain circumstances. Normally,
83        when pcre_exec() would call its internal match() function recursively and
84        immediately return the result unconditionally, it uses a "tail recursion"
85        feature to save stack. However, when a subpattern that can match an empty
86        string has an unlimited repetition quantifier, it no longer makes this
87        optimization. That gives it a stack frame in which to save the data for
88        checking that an empty string has been matched. Previously this was taken
89        from the 1000-entry workspace that had been reserved. So now there is no
90        explicit limit, but more stack is used.
91    
92     8. Applied Daniel's patches to solve problems with the import/export magic
93        syntax that is required for Windows, and which was going wrong for the
94        pcreposix and pcrecpp parts of the library. These were overlooked when this
95        problem was solved for the main library.
96    
97     9. There were some crude static tests to avoid integer overflow when computing
98        the size of patterns that contain repeated groups with explicit upper
99        limits. As the maximum quantifier is 65535, the maximum group length was
100        set at 30,000 so that the product of these two numbers did not overflow a
101        32-bit integer. However, it turns out that people want to use groups that
102        are longer than 30,000 bytes (though not repeat them that many times).
103        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
104        made it possible to implement the integer overflow checks in a much more
105        dynamic way, which I have now done. The artificial limitation on group
106        length has been removed - we now have only the limit on the total length of
107        the compiled pattern, which depends on the LINK_SIZE setting.
108    
109    10. Fixed a bug in the documentation for get/copy named substring when
110        duplicate names are permitted. If none of the named substrings are set, the
111        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
112        empty string.
113    
114    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
115        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
116        because the ] is interpreted as the first data character and the
117        terminating ] is not found. PCRE has been made compatible with Perl in this
118        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
119        cause memory overwriting.
120    
121    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
122        string has been matched (to stop an infinite loop). It was not recognizing
123        a conditional subpattern that could match an empty string if that
124        subpattern was within another subpattern. For example, it looped when
125        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
126        condition was not nested. This bug has been fixed.
127    
128    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
129        past the start of the subject in the presence of bytes with the top bit
130        set, for example "\x8aBCD".
131    
132    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
133        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
134    
135    14. Optimized (?!) to (*FAIL).
136    
137    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
138        This restricts code points to be within the range 0 to 0x10FFFF, excluding
139        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
140        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
141        does: it's just the validity check that is more restrictive.
142    
143    16. Inserted checks for integer overflows during escape sequence (backslash)
144        processing, and also fixed erroneous offset values for syntax errors during
145        backslash processing.
146    
147    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
148        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
149    
150    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
151        caused an overrun.
152    
153    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
154        something other than just ASCII characters) inside a group that had an
155        unlimited repeat caused a loop at compile time (while checking to see
156        whether the group could match an empty string).
157    
158    20. Debugging a pattern containing \p or \P could cause a crash. For example,
159        [\P{Any}] did so. (Error in the code for printing property names.)
160    
161    21. An orphan \E inside a character class could cause a crash.
162    
163    22. A repeated capturing bracket such as (A)? could cause a wild memory
164        reference during compilation.
165    
166    23. There are several functions in pcre_compile() that scan along a compiled
167        expression for various reasons (e.g. to see if it's fixed length for look
168        behind). There were bugs in these functions when a repeated \p or \P was
169        present in the pattern. These operators have additional parameters compared
170        with \d, etc, and these were not being taken into account when moving along
171        the compiled data. Specifically:
172    
173        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
174            length.
175    
176        (b) An item such as \pL+ within a repeated group could cause crashes or
177            loops.
178    
179        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
180            "reference to non-existent subpattern" error.
181    
182        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
183    
184    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
185        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
186    
187    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
188    
189    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
190        character were causing crashes (broken optimization).
191    
192    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
193        \p or \P) caused a compile-time loop.
194    
195    28. More problems have arisen in unanchored patterns when CRLF is a valid line
196        break. For example, the unstudied pattern [\r\n]A does not match the string
197        "\r\nA" because change 7.0/46 below moves the current point on by two
198        characters after failing to match at the start. However, the pattern \nA
199        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
200        the same is true. There doesn't seem any very clean way out of this, but
201        what I have chosen to do makes the common cases work: PCRE now takes note
202        of whether there can be an explicit match for \r or \n anywhere in the
203        pattern, and if so, 7.0/46 no longer applies. As part of this change,
204        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
205        pattern has explicit CR or LF references.
206    
207    29. Added (*CR) etc for changing newline setting at start of pattern.
208    
209    
210    Version 7.2 19-Jun-07
211  ---------------------  ---------------------
212    
213   1. If the fr_FR locale cannot be found for test 3, try the "french" locale,   1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
# Line 21  Version 7.2 01-May-07 Line 227  Version 7.2 01-May-07
227      stack recursion. This gives a massive performance boost under BSD, but just      stack recursion. This gives a massive performance boost under BSD, but just
228      a small improvement under Linux. However, it saves one field in the frame      a small improvement under Linux. However, it saves one field in the frame
229      in all cases.      in all cases.
230    
231   6. Added more features from the forthcoming Perl 5.10:   6. Added more features from the forthcoming Perl 5.10:
232    
233      (a) (?-n) (where n is a string of digits) is a relative subroutine or      (a) (?-n) (where n is a string of digits) is a relative subroutine or
234          recursion call. It refers to the nth most recently opened parentheses.          recursion call. It refers to the nth most recently opened parentheses.
235    
236      (b) (?+n) is also a relative subroutine call; it refers to the nth next      (b) (?+n) is also a relative subroutine call; it refers to the nth next
237          to be opened parentheses.          to be opened parentheses.
238    
239      (c) Conditions that refer to capturing parentheses can be specified      (c) Conditions that refer to capturing parentheses can be specified
240          relatively, for example, (?(-2)... or (?(+3)...          relatively, for example, (?(-2)... or (?(+3)...
241    
242      (d) \K resets the start of the current match so that everything before      (d) \K resets the start of the current match so that everything before
243          is not part of it.          is not part of it.
244    
245        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
246    
247        (f) \g{name} is another synonym - part of Perl 5.10's unification of
248            reference syntax.
249    
250        (g) (?| introduces a group in which the numbering of parentheses in each
251            alternative starts with the same number.
252    
253        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
254    
255     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
256        PCRE_INFO_JCHANGED.
257    
258     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
259        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
260        for detecting groups that can match an empty string.
261    
262     9. A pattern with a very large number of alternatives (more than several
263        hundred) was running out of internal workspace during the pre-compile
264        phase, where pcre_compile() figures out how much memory will be needed. A
265        bit of new cunning has reduced the workspace needed for groups with
266        alternatives. The 1000-alternative test pattern now uses 12 bytes of
267        workspace instead of running out of the 4096 that are available.
268    
269    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
270    
271    11. Applied patch from Google to remove an optimization that didn't quite work.
272        The report of the bug said:
273    
274          pcrecpp::RE("a*").FullMatch("aaa") matches, while
275          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
276          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
277    
278    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
279        it matched the wrong number of bytes.
280    
281    
282  Version 7.1 24-Apr-07  Version 7.1 24-Apr-07

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