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revision 150 by ph10, Tue Apr 17 08:22:40 2007 UTC revision 234 by ph10, Tue Sep 11 11:36:27 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 7.1 12-Mar-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
43        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
44        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
46        compiled (which of course may be different). I have changed it back to:
47    
48          #include "pcre.h"
49    
50        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
52        by the VPATH setting the Makefile.
53    
54     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
56        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
57        characters but of course it shouldn't be taken as a newline when it is part
58        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
60        characters when looking for a newline.
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
205    ---------------------
206    
207     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
208        which is apparently normally available under Windows.
209    
210     2. Re-jig the pcregrep tests with different newline settings in an attempt
211        to make them independent of the local environment's newline setting.
212    
213     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
214    
215     4. Some of the "internals" tests were previously cut out when the link size
216        was not 2, because the output contained actual offsets. The recent new
217        "Z" feature of pcretest means that these can be cut out, making the tests
218        usable with all link sizes.
219    
220     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
221        stack recursion. This gives a massive performance boost under BSD, but just
222        a small improvement under Linux. However, it saves one field in the frame
223        in all cases.
224    
225     6. Added more features from the forthcoming Perl 5.10:
226    
227        (a) (?-n) (where n is a string of digits) is a relative subroutine or
228            recursion call. It refers to the nth most recently opened parentheses.
229    
230        (b) (?+n) is also a relative subroutine call; it refers to the nth next
231            to be opened parentheses.
232    
233        (c) Conditions that refer to capturing parentheses can be specified
234            relatively, for example, (?(-2)... or (?(+3)...
235    
236        (d) \K resets the start of the current match so that everything before
237            is not part of it.
238    
239        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
240    
241        (f) \g{name} is another synonym - part of Perl 5.10's unification of
242            reference syntax.
243    
244        (g) (?| introduces a group in which the numbering of parentheses in each
245            alternative starts with the same number.
246    
247        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
248    
249     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
250        PCRE_INFO_JCHANGED.
251    
252     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
253        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
254        for detecting groups that can match an empty string.
255    
256     9. A pattern with a very large number of alternatives (more than several
257        hundred) was running out of internal workspace during the pre-compile
258        phase, where pcre_compile() figures out how much memory will be needed. A
259        bit of new cunning has reduced the workspace needed for groups with
260        alternatives. The 1000-alternative test pattern now uses 12 bytes of
261        workspace instead of running out of the 4096 that are available.
262    
263    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
264    
265    11. Applied patch from Google to remove an optimization that didn't quite work.
266        The report of the bug said:
267    
268          pcrecpp::RE("a*").FullMatch("aaa") matches, while
269          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
270          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
271    
272    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
273        it matched the wrong number of bytes.
274    
275    
276    Version 7.1 24-Apr-07
277  ---------------------  ---------------------
278    
279   1. Applied Bob Rossi and Daniel G's patches to convert the build system to one   1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
# Line 143  Version 7.1 12-Mar-07 Line 415  Version 7.1 12-Mar-07
415  21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or  21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
416      CRLF as a newline sequence.      CRLF as a newline sequence.
417    
418    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
419        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
420        I have nevertheless tidied it up.
421    
422    23. Added some casts to kill warnings from HP-UX ia64 compiler.
423    
424    24. Added a man page for pcre-config.
425    
426    
427  Version 7.0 19-Dec-06  Version 7.0 19-Dec-06
428  ---------------------  ---------------------

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