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revision 158 by ph10, Tue May 1 10:30:14 2007 UTC revision 244 by ph10, Fri Sep 14 09:14:24 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    10. It was pointed out to me that arrays of string pointers cause lots of
45        relocations when a shared library is dynamically loaded. A technique of
46        using a single long string with a table of offsets can drastically reduce
47        these. I have refactored PCRE in four places to do this. The result is
48        dramatic:
49    
50          Originally:                          290
51          After changing UCP table:            187
52          After changing error message table:   43
53          After changing table of "verbs"       36
54          After changing table of Posix names   22
55    
56        Thanks to the folks working on Gregex for glib for this insight.
57    
58    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
59        unicode-properties was also set.
60    
61    
62    Version 7.3 28-Aug-07
63    ---------------------
64    
65     1. In the rejigging of the build system that eventually resulted in 7.1, the
66        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
67        brackets there is not right, since it causes compilers to look for an
68        installed pcre.h, not the version that is in the source that is being
69        compiled (which of course may be different). I have changed it back to:
70    
71          #include "pcre.h"
72    
73        I have a vague recollection that the change was concerned with compiling in
74        different directories, but in the new build system, that is taken care of
75        by the VPATH setting the Makefile.
76    
77     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
78        when the subject happened to end in the byte 0x85 (e.g. if the last
79        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
80        characters but of course it shouldn't be taken as a newline when it is part
81        of another character. The bug was that, for an unlimited repeat of . in
82        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
83        characters when looking for a newline.
84    
85     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
86    
87     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
88        in debug output.
89    
90     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
91        long printing in the pcrecpp unittest when running under MinGW.
92    
93     6. ESC_K was left out of the EBCDIC table.
94    
95     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
96        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
97        limit also applies to "virtual nesting" when a pattern is recursive, and in
98        this case 1000 isn't so big. I have been able to remove this limit at the
99        expense of backing off one optimization in certain circumstances. Normally,
100        when pcre_exec() would call its internal match() function recursively and
101        immediately return the result unconditionally, it uses a "tail recursion"
102        feature to save stack. However, when a subpattern that can match an empty
103        string has an unlimited repetition quantifier, it no longer makes this
104        optimization. That gives it a stack frame in which to save the data for
105        checking that an empty string has been matched. Previously this was taken
106        from the 1000-entry workspace that had been reserved. So now there is no
107        explicit limit, but more stack is used.
108    
109     8. Applied Daniel's patches to solve problems with the import/export magic
110        syntax that is required for Windows, and which was going wrong for the
111        pcreposix and pcrecpp parts of the library. These were overlooked when this
112        problem was solved for the main library.
113    
114     9. There were some crude static tests to avoid integer overflow when computing
115        the size of patterns that contain repeated groups with explicit upper
116        limits. As the maximum quantifier is 65535, the maximum group length was
117        set at 30,000 so that the product of these two numbers did not overflow a
118        32-bit integer. However, it turns out that people want to use groups that
119        are longer than 30,000 bytes (though not repeat them that many times).
120        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
121        made it possible to implement the integer overflow checks in a much more
122        dynamic way, which I have now done. The artificial limitation on group
123        length has been removed - we now have only the limit on the total length of
124        the compiled pattern, which depends on the LINK_SIZE setting.
125    
126    10. Fixed a bug in the documentation for get/copy named substring when
127        duplicate names are permitted. If none of the named substrings are set, the
128        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
129        empty string.
130    
131    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
132        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
133        because the ] is interpreted as the first data character and the
134        terminating ] is not found. PCRE has been made compatible with Perl in this
135        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
136        cause memory overwriting.
137    
138    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
139        string has been matched (to stop an infinite loop). It was not recognizing
140        a conditional subpattern that could match an empty string if that
141        subpattern was within another subpattern. For example, it looped when
142        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
143        condition was not nested. This bug has been fixed.
144    
145    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
146        past the start of the subject in the presence of bytes with the top bit
147        set, for example "\x8aBCD".
148    
149    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
150        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
151    
152    14. Optimized (?!) to (*FAIL).
153    
154    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
155        This restricts code points to be within the range 0 to 0x10FFFF, excluding
156        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
157        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
158        does: it's just the validity check that is more restrictive.
159    
160    16. Inserted checks for integer overflows during escape sequence (backslash)
161        processing, and also fixed erroneous offset values for syntax errors during
162        backslash processing.
163    
164    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
165        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
166    
167    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
168        caused an overrun.
169    
170    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
171        something other than just ASCII characters) inside a group that had an
172        unlimited repeat caused a loop at compile time (while checking to see
173        whether the group could match an empty string).
174    
175    20. Debugging a pattern containing \p or \P could cause a crash. For example,
176        [\P{Any}] did so. (Error in the code for printing property names.)
177    
178    21. An orphan \E inside a character class could cause a crash.
179    
180    22. A repeated capturing bracket such as (A)? could cause a wild memory
181        reference during compilation.
182    
183    23. There are several functions in pcre_compile() that scan along a compiled
184        expression for various reasons (e.g. to see if it's fixed length for look
185        behind). There were bugs in these functions when a repeated \p or \P was
186        present in the pattern. These operators have additional parameters compared
187        with \d, etc, and these were not being taken into account when moving along
188        the compiled data. Specifically:
189    
190        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
191            length.
192    
193        (b) An item such as \pL+ within a repeated group could cause crashes or
194            loops.
195    
196        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
197            "reference to non-existent subpattern" error.
198    
199        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
200    
201    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
202        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
203    
204    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
205    
206    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
207        character were causing crashes (broken optimization).
208    
209    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
210        \p or \P) caused a compile-time loop.
211    
212    28. More problems have arisen in unanchored patterns when CRLF is a valid line
213        break. For example, the unstudied pattern [\r\n]A does not match the string
214        "\r\nA" because change 7.0/46 below moves the current point on by two
215        characters after failing to match at the start. However, the pattern \nA
216        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
217        the same is true. There doesn't seem any very clean way out of this, but
218        what I have chosen to do makes the common cases work: PCRE now takes note
219        of whether there can be an explicit match for \r or \n anywhere in the
220        pattern, and if so, 7.0/46 no longer applies. As part of this change,
221        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
222        pattern has explicit CR or LF references.
223    
224    29. Added (*CR) etc for changing newline setting at start of pattern.
225    
226    
227    Version 7.2 19-Jun-07
228  ---------------------  ---------------------
229    
230   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,
231      which is apparently normally available under Windows.      which is apparently normally available under Windows.
232    
233   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
234      to make them independent of the local environment's newline setting.      to make them independent of the local environment's newline setting.
235    
236     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
237    
238     4. Some of the "internals" tests were previously cut out when the link size
239        was not 2, because the output contained actual offsets. The recent new
240        "Z" feature of pcretest means that these can be cut out, making the tests
241        usable with all link sizes.
242    
243     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
244        stack recursion. This gives a massive performance boost under BSD, but just
245        a small improvement under Linux. However, it saves one field in the frame
246        in all cases.
247    
248     6. Added more features from the forthcoming Perl 5.10:
249    
250        (a) (?-n) (where n is a string of digits) is a relative subroutine or
251            recursion call. It refers to the nth most recently opened parentheses.
252    
253        (b) (?+n) is also a relative subroutine call; it refers to the nth next
254            to be opened parentheses.
255    
256        (c) Conditions that refer to capturing parentheses can be specified
257            relatively, for example, (?(-2)... or (?(+3)...
258    
259        (d) \K resets the start of the current match so that everything before
260            is not part of it.
261    
262        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
263    
264        (f) \g{name} is another synonym - part of Perl 5.10's unification of
265            reference syntax.
266    
267        (g) (?| introduces a group in which the numbering of parentheses in each
268            alternative starts with the same number.
269    
270        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
271    
272     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
273        PCRE_INFO_JCHANGED.
274    
275     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
276        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
277        for detecting groups that can match an empty string.
278    
279     9. A pattern with a very large number of alternatives (more than several
280        hundred) was running out of internal workspace during the pre-compile
281        phase, where pcre_compile() figures out how much memory will be needed. A
282        bit of new cunning has reduced the workspace needed for groups with
283        alternatives. The 1000-alternative test pattern now uses 12 bytes of
284        workspace instead of running out of the 4096 that are available.
285    
286    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
287    
288    11. Applied patch from Google to remove an optimization that didn't quite work.
289        The report of the bug said:
290    
291          pcrecpp::RE("a*").FullMatch("aaa") matches, while
292          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
293          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
294    
295    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
296        it matched the wrong number of bytes.
297    
298    
299  Version 7.1 24-Apr-07  Version 7.1 24-Apr-07
300  ---------------------  ---------------------

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