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revision 176 by ph10, Mon Jun 11 13:48:37 2007 UTC revision 253 by ph10, Mon Sep 17 10:51:30 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 7.2 05-June-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 when the
36        windows.h file is present (where 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    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
62    
63    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
64        checked only for CRLF.
65    
66    
67    Version 7.3 28-Aug-07
68    ---------------------
69    
70     1. In the rejigging of the build system that eventually resulted in 7.1, the
71        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
72        brackets there is not right, since it causes compilers to look for an
73        installed pcre.h, not the version that is in the source that is being
74        compiled (which of course may be different). I have changed it back to:
75    
76          #include "pcre.h"
77    
78        I have a vague recollection that the change was concerned with compiling in
79        different directories, but in the new build system, that is taken care of
80        by the VPATH setting the Makefile.
81    
82     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
83        when the subject happened to end in the byte 0x85 (e.g. if the last
84        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
85        characters but of course it shouldn't be taken as a newline when it is part
86        of another character. The bug was that, for an unlimited repeat of . in
87        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
88        characters when looking for a newline.
89    
90     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
91    
92     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
93        in debug output.
94    
95     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
96        long printing in the pcrecpp unittest when running under MinGW.
97    
98     6. ESC_K was left out of the EBCDIC table.
99    
100     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
101        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
102        limit also applies to "virtual nesting" when a pattern is recursive, and in
103        this case 1000 isn't so big. I have been able to remove this limit at the
104        expense of backing off one optimization in certain circumstances. Normally,
105        when pcre_exec() would call its internal match() function recursively and
106        immediately return the result unconditionally, it uses a "tail recursion"
107        feature to save stack. However, when a subpattern that can match an empty
108        string has an unlimited repetition quantifier, it no longer makes this
109        optimization. That gives it a stack frame in which to save the data for
110        checking that an empty string has been matched. Previously this was taken
111        from the 1000-entry workspace that had been reserved. So now there is no
112        explicit limit, but more stack is used.
113    
114     8. Applied Daniel's patches to solve problems with the import/export magic
115        syntax that is required for Windows, and which was going wrong for the
116        pcreposix and pcrecpp parts of the library. These were overlooked when this
117        problem was solved for the main library.
118    
119     9. There were some crude static tests to avoid integer overflow when computing
120        the size of patterns that contain repeated groups with explicit upper
121        limits. As the maximum quantifier is 65535, the maximum group length was
122        set at 30,000 so that the product of these two numbers did not overflow a
123        32-bit integer. However, it turns out that people want to use groups that
124        are longer than 30,000 bytes (though not repeat them that many times).
125        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
126        made it possible to implement the integer overflow checks in a much more
127        dynamic way, which I have now done. The artificial limitation on group
128        length has been removed - we now have only the limit on the total length of
129        the compiled pattern, which depends on the LINK_SIZE setting.
130    
131    10. Fixed a bug in the documentation for get/copy named substring when
132        duplicate names are permitted. If none of the named substrings are set, the
133        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
134        empty string.
135    
136    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
137        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
138        because the ] is interpreted as the first data character and the
139        terminating ] is not found. PCRE has been made compatible with Perl in this
140        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
141        cause memory overwriting.
142    
143    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
144        string has been matched (to stop an infinite loop). It was not recognizing
145        a conditional subpattern that could match an empty string if that
146        subpattern was within another subpattern. For example, it looped when
147        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
148        condition was not nested. This bug has been fixed.
149    
150    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
151        past the start of the subject in the presence of bytes with the top bit
152        set, for example "\x8aBCD".
153    
154    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
155        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
156    
157    14. Optimized (?!) to (*FAIL).
158    
159    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
160        This restricts code points to be within the range 0 to 0x10FFFF, excluding
161        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
162        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
163        does: it's just the validity check that is more restrictive.
164    
165    16. Inserted checks for integer overflows during escape sequence (backslash)
166        processing, and also fixed erroneous offset values for syntax errors during
167        backslash processing.
168    
169    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
170        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
171    
172    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
173        caused an overrun.
174    
175    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
176        something other than just ASCII characters) inside a group that had an
177        unlimited repeat caused a loop at compile time (while checking to see
178        whether the group could match an empty string).
179    
180    20. Debugging a pattern containing \p or \P could cause a crash. For example,
181        [\P{Any}] did so. (Error in the code for printing property names.)
182    
183    21. An orphan \E inside a character class could cause a crash.
184    
185    22. A repeated capturing bracket such as (A)? could cause a wild memory
186        reference during compilation.
187    
188    23. There are several functions in pcre_compile() that scan along a compiled
189        expression for various reasons (e.g. to see if it's fixed length for look
190        behind). There were bugs in these functions when a repeated \p or \P was
191        present in the pattern. These operators have additional parameters compared
192        with \d, etc, and these were not being taken into account when moving along
193        the compiled data. Specifically:
194    
195        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
196            length.
197    
198        (b) An item such as \pL+ within a repeated group could cause crashes or
199            loops.
200    
201        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
202            "reference to non-existent subpattern" error.
203    
204        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
205    
206    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
207        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
208    
209    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
210    
211    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
212        character were causing crashes (broken optimization).
213    
214    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
215        \p or \P) caused a compile-time loop.
216    
217    28. More problems have arisen in unanchored patterns when CRLF is a valid line
218        break. For example, the unstudied pattern [\r\n]A does not match the string
219        "\r\nA" because change 7.0/46 below moves the current point on by two
220        characters after failing to match at the start. However, the pattern \nA
221        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
222        the same is true. There doesn't seem any very clean way out of this, but
223        what I have chosen to do makes the common cases work: PCRE now takes note
224        of whether there can be an explicit match for \r or \n anywhere in the
225        pattern, and if so, 7.0/46 no longer applies. As part of this change,
226        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
227        pattern has explicit CR or LF references.
228    
229    29. Added (*CR) etc for changing newline setting at start of pattern.
230    
231    
232    Version 7.2 19-Jun-07
233  ---------------------  ---------------------
234    
235   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 40  Version 7.2 05-June-07 Line 268  Version 7.2 05-June-07
268    
269      (f) \g{name} is another synonym - part of Perl 5.10's unification of      (f) \g{name} is another synonym - part of Perl 5.10's unification of
270          reference syntax.          reference syntax.
271    
272      (g) (?| introduces a group in which the numbering of parentheses in each      (g) (?| introduces a group in which the numbering of parentheses in each
273          alternative starts with the same number.          alternative starts with the same number.
274    
275        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
276    
277   7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and   7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
278      PCRE_INFO_JCHANGED.      PCRE_INFO_JCHANGED.
# Line 57  Version 7.2 05-June-07 Line 287  Version 7.2 05-June-07
287      bit of new cunning has reduced the workspace needed for groups with      bit of new cunning has reduced the workspace needed for groups with
288      alternatives. The 1000-alternative test pattern now uses 12 bytes of      alternatives. The 1000-alternative test pattern now uses 12 bytes of
289      workspace instead of running out of the 4096 that are available.      workspace instead of running out of the 4096 that are available.
290    
291  10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.  10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
292    
293    11. Applied patch from Google to remove an optimization that didn't quite work.
294        The report of the bug said:
295    
296          pcrecpp::RE("a*").FullMatch("aaa") matches, while
297          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
298          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
299    
300    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
301        it matched the wrong number of bytes.
302    
303    
304  Version 7.1 24-Apr-07  Version 7.1 24-Apr-07
305  ---------------------  ---------------------

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