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revision 159 by ph10, Wed May 2 10:27:18 2007 UTC revision 233 by ph10, Tue Sep 11 11:26:11 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    
35    Version 7.3 28-Aug-07
36    ---------------------
37    
38     1. In the rejigging of the build system that eventually resulted in 7.1, the
39        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
40        brackets there is not right, since it causes compilers to look for an
41        installed pcre.h, not the version that is in the source that is being
42        compiled (which of course may be different). I have changed it back to:
43    
44          #include "pcre.h"
45    
46        I have a vague recollection that the change was concerned with compiling in
47        different directories, but in the new build system, that is taken care of
48        by the VPATH setting the Makefile.
49    
50     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
51        when the subject happened to end in the byte 0x85 (e.g. if the last
52        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
53        characters but of course it shouldn't be taken as a newline when it is part
54        of another character. The bug was that, for an unlimited repeat of . in
55        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
56        characters when looking for a newline.
57    
58     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
59    
60     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
61        in debug output.
62    
63     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
64        long printing in the pcrecpp unittest when running under MinGW.
65    
66     6. ESC_K was left out of the EBCDIC table.
67    
68     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
69        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
70        limit also applies to "virtual nesting" when a pattern is recursive, and in
71        this case 1000 isn't so big. I have been able to remove this limit at the
72        expense of backing off one optimization in certain circumstances. Normally,
73        when pcre_exec() would call its internal match() function recursively and
74        immediately return the result unconditionally, it uses a "tail recursion"
75        feature to save stack. However, when a subpattern that can match an empty
76        string has an unlimited repetition quantifier, it no longer makes this
77        optimization. That gives it a stack frame in which to save the data for
78        checking that an empty string has been matched. Previously this was taken
79        from the 1000-entry workspace that had been reserved. So now there is no
80        explicit limit, but more stack is used.
81    
82     8. Applied Daniel's patches to solve problems with the import/export magic
83        syntax that is required for Windows, and which was going wrong for the
84        pcreposix and pcrecpp parts of the library. These were overlooked when this
85        problem was solved for the main library.
86    
87     9. There were some crude static tests to avoid integer overflow when computing
88        the size of patterns that contain repeated groups with explicit upper
89        limits. As the maximum quantifier is 65535, the maximum group length was
90        set at 30,000 so that the product of these two numbers did not overflow a
91        32-bit integer. However, it turns out that people want to use groups that
92        are longer than 30,000 bytes (though not repeat them that many times).
93        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
94        made it possible to implement the integer overflow checks in a much more
95        dynamic way, which I have now done. The artificial limitation on group
96        length has been removed - we now have only the limit on the total length of
97        the compiled pattern, which depends on the LINK_SIZE setting.
98    
99    10. Fixed a bug in the documentation for get/copy named substring when
100        duplicate names are permitted. If none of the named substrings are set, the
101        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
102        empty string.
103    
104    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
105        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
106        because the ] is interpreted as the first data character and the
107        terminating ] is not found. PCRE has been made compatible with Perl in this
108        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
109        cause memory overwriting.
110    
111    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
112        string has been matched (to stop an infinite loop). It was not recognizing
113        a conditional subpattern that could match an empty string if that
114        subpattern was within another subpattern. For example, it looped when
115        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
116        condition was not nested. This bug has been fixed.
117    
118    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
119        past the start of the subject in the presence of bytes with the top bit
120        set, for example "\x8aBCD".
121    
122    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
123        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
124    
125    14. Optimized (?!) to (*FAIL).
126    
127    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
128        This restricts code points to be within the range 0 to 0x10FFFF, excluding
129        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
130        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
131        does: it's just the validity check that is more restrictive.
132    
133    16. Inserted checks for integer overflows during escape sequence (backslash)
134        processing, and also fixed erroneous offset values for syntax errors during
135        backslash processing.
136    
137    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
138        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
139    
140    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
141        caused an overrun.
142    
143    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
144        something other than just ASCII characters) inside a group that had an
145        unlimited repeat caused a loop at compile time (while checking to see
146        whether the group could match an empty string).
147    
148    20. Debugging a pattern containing \p or \P could cause a crash. For example,
149        [\P{Any}] did so. (Error in the code for printing property names.)
150    
151    21. An orphan \E inside a character class could cause a crash.
152    
153    22. A repeated capturing bracket such as (A)? could cause a wild memory
154        reference during compilation.
155    
156    23. There are several functions in pcre_compile() that scan along a compiled
157        expression for various reasons (e.g. to see if it's fixed length for look
158        behind). There were bugs in these functions when a repeated \p or \P was
159        present in the pattern. These operators have additional parameters compared
160        with \d, etc, and these were not being taken into account when moving along
161        the compiled data. Specifically:
162    
163        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
164            length.
165    
166        (b) An item such as \pL+ within a repeated group could cause crashes or
167            loops.
168    
169        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
170            "reference to non-existent subpattern" error.
171    
172        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
173    
174    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
175        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
176    
177    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
178    
179    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
180        character were causing crashes (broken optimization).
181    
182    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
183        \p or \P) caused a compile-time loop.
184    
185    28. More problems have arisen in unanchored patterns when CRLF is a valid line
186        break. For example, the unstudied pattern [\r\n]A does not match the string
187        "\r\nA" because change 7.0/46 below moves the current point on by two
188        characters after failing to match at the start. However, the pattern \nA
189        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
190        the same is true. There doesn't seem any very clean way out of this, but
191        what I have chosen to do makes the common cases work: PCRE now takes note
192        of whether there can be an explicit match for \r or \n anywhere in the
193        pattern, and if so, 7.0/46 no longer applies. As part of this change,
194        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
195        pattern has explicit CR or LF references.
196    
197    29. Added (*CR) etc for changing newline setting at start of pattern.
198    
199    
200    Version 7.2 19-Jun-07
201  ---------------------  ---------------------
202    
203   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 9  Version 7.2 01-May-07 Line 205  Version 7.2 01-May-07
205    
206   2. Re-jig the pcregrep tests with different newline settings in an attempt   2. Re-jig the pcregrep tests with different newline settings in an attempt
207      to make them independent of the local environment's newline setting.      to make them independent of the local environment's newline setting.
208    
209   3. Add code to configure.ac to remove -g from the CFLAGS default settings.   3. Add code to configure.ac to remove -g from the CFLAGS default settings.
210    
211     4. Some of the "internals" tests were previously cut out when the link size
212        was not 2, because the output contained actual offsets. The recent new
213        "Z" feature of pcretest means that these can be cut out, making the tests
214        usable with all link sizes.
215    
216     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
217        stack recursion. This gives a massive performance boost under BSD, but just
218        a small improvement under Linux. However, it saves one field in the frame
219        in all cases.
220    
221     6. Added more features from the forthcoming Perl 5.10:
222    
223        (a) (?-n) (where n is a string of digits) is a relative subroutine or
224            recursion call. It refers to the nth most recently opened parentheses.
225    
226        (b) (?+n) is also a relative subroutine call; it refers to the nth next
227            to be opened parentheses.
228    
229        (c) Conditions that refer to capturing parentheses can be specified
230            relatively, for example, (?(-2)... or (?(+3)...
231    
232        (d) \K resets the start of the current match so that everything before
233            is not part of it.
234    
235        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
236    
237        (f) \g{name} is another synonym - part of Perl 5.10's unification of
238            reference syntax.
239    
240        (g) (?| introduces a group in which the numbering of parentheses in each
241            alternative starts with the same number.
242    
243        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
244    
245     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
246        PCRE_INFO_JCHANGED.
247    
248     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
249        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
250        for detecting groups that can match an empty string.
251    
252     9. A pattern with a very large number of alternatives (more than several
253        hundred) was running out of internal workspace during the pre-compile
254        phase, where pcre_compile() figures out how much memory will be needed. A
255        bit of new cunning has reduced the workspace needed for groups with
256        alternatives. The 1000-alternative test pattern now uses 12 bytes of
257        workspace instead of running out of the 4096 that are available.
258    
259    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
260    
261    11. Applied patch from Google to remove an optimization that didn't quite work.
262        The report of the bug said:
263    
264          pcrecpp::RE("a*").FullMatch("aaa") matches, while
265          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
266          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
267    
268    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
269        it matched the wrong number of bytes.
270    
271    
272  Version 7.1 24-Apr-07  Version 7.1 24-Apr-07

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