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revision 185 by ph10, Tue Jun 19 13:39:46 2007 UTC revision 257 by ph10, Wed Sep 19 09:11:19 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 7.2 19-June-07  Version 7.4 10-Sep-07
5    ---------------------
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.
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.
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.
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.
29    5.  doc/pcresyntax.html was missing from the distribution.
31    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
32        compatibility, even though it is no longer used.
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). [This was
37        reversed later after testing - see 16 below.]
39    8.  Changed all #include <config.h> to #include "config.h". There were also
40        some further <pcre.h> cases that I changed to "pcre.h".
42    9.  When pcregrep was used with the --colour option, it missed the line ending
43        sequence off the lines that it output.
45    10. It was pointed out to me that arrays of string pointers cause lots of
46        relocations when a shared library is dynamically loaded. A technique of
47        using a single long string with a table of offsets can drastically reduce
48        these. I have refactored PCRE in four places to do this. The result is
49        dramatic:
51          Originally:                          290
52          After changing UCP table:            187
53          After changing error message table:   43
54          After changing table of "verbs"       36
55          After changing table of Posix names   22
57        Thanks to the folks working on Gregex for glib for this insight.
59    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
60        unicode-properties was also set.
62    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
64    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
65        checked only for CRLF.
67    14. Added casts to pcretest.c to avoid compiler warnings.
69    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
71    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
72        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
73        entirely. This removes changes made in 7 above.
76    Version 7.3 28-Aug-07
77    ---------------------
79     1. In the rejigging of the build system that eventually resulted in 7.1, the
80        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
81        brackets there is not right, since it causes compilers to look for an
82        installed pcre.h, not the version that is in the source that is being
83        compiled (which of course may be different). I have changed it back to:
85          #include "pcre.h"
87        I have a vague recollection that the change was concerned with compiling in
88        different directories, but in the new build system, that is taken care of
89        by the VPATH setting the Makefile.
91     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
92        when the subject happened to end in the byte 0x85 (e.g. if the last
93        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
94        characters but of course it shouldn't be taken as a newline when it is part
95        of another character. The bug was that, for an unlimited repeat of . in
96        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
97        characters when looking for a newline.
99     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
101     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
102        in debug output.
104     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
105        long printing in the pcrecpp unittest when running under MinGW.
107     6. ESC_K was left out of the EBCDIC table.
109     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
110        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
111        limit also applies to "virtual nesting" when a pattern is recursive, and in
112        this case 1000 isn't so big. I have been able to remove this limit at the
113        expense of backing off one optimization in certain circumstances. Normally,
114        when pcre_exec() would call its internal match() function recursively and
115        immediately return the result unconditionally, it uses a "tail recursion"
116        feature to save stack. However, when a subpattern that can match an empty
117        string has an unlimited repetition quantifier, it no longer makes this
118        optimization. That gives it a stack frame in which to save the data for
119        checking that an empty string has been matched. Previously this was taken
120        from the 1000-entry workspace that had been reserved. So now there is no
121        explicit limit, but more stack is used.
123     8. Applied Daniel's patches to solve problems with the import/export magic
124        syntax that is required for Windows, and which was going wrong for the
125        pcreposix and pcrecpp parts of the library. These were overlooked when this
126        problem was solved for the main library.
128     9. There were some crude static tests to avoid integer overflow when computing
129        the size of patterns that contain repeated groups with explicit upper
130        limits. As the maximum quantifier is 65535, the maximum group length was
131        set at 30,000 so that the product of these two numbers did not overflow a
132        32-bit integer. However, it turns out that people want to use groups that
133        are longer than 30,000 bytes (though not repeat them that many times).
134        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
135        made it possible to implement the integer overflow checks in a much more
136        dynamic way, which I have now done. The artificial limitation on group
137        length has been removed - we now have only the limit on the total length of
138        the compiled pattern, which depends on the LINK_SIZE setting.
140    10. Fixed a bug in the documentation for get/copy named substring when
141        duplicate names are permitted. If none of the named substrings are set, the
142        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
143        empty string.
145    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
146        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
147        because the ] is interpreted as the first data character and the
148        terminating ] is not found. PCRE has been made compatible with Perl in this
149        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
150        cause memory overwriting.
152    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
153        string has been matched (to stop an infinite loop). It was not recognizing
154        a conditional subpattern that could match an empty string if that
155        subpattern was within another subpattern. For example, it looped when
156        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
157        condition was not nested. This bug has been fixed.
159    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
160        past the start of the subject in the presence of bytes with the top bit
161        set, for example "\x8aBCD".
163    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
164        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
166    14. Optimized (?!) to (*FAIL).
168    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
169        This restricts code points to be within the range 0 to 0x10FFFF, excluding
170        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
171        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
172        does: it's just the validity check that is more restrictive.
174    16. Inserted checks for integer overflows during escape sequence (backslash)
175        processing, and also fixed erroneous offset values for syntax errors during
176        backslash processing.
178    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
179        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
181    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
182        caused an overrun.
184    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
185        something other than just ASCII characters) inside a group that had an
186        unlimited repeat caused a loop at compile time (while checking to see
187        whether the group could match an empty string).
189    20. Debugging a pattern containing \p or \P could cause a crash. For example,
190        [\P{Any}] did so. (Error in the code for printing property names.)
192    21. An orphan \E inside a character class could cause a crash.
194    22. A repeated capturing bracket such as (A)? could cause a wild memory
195        reference during compilation.
197    23. There are several functions in pcre_compile() that scan along a compiled
198        expression for various reasons (e.g. to see if it's fixed length for look
199        behind). There were bugs in these functions when a repeated \p or \P was
200        present in the pattern. These operators have additional parameters compared
201        with \d, etc, and these were not being taken into account when moving along
202        the compiled data. Specifically:
204        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
205            length.
207        (b) An item such as \pL+ within a repeated group could cause crashes or
208            loops.
210        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
211            "reference to non-existent subpattern" error.
213        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
215    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
216        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
218    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
220    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
221        character were causing crashes (broken optimization).
223    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
224        \p or \P) caused a compile-time loop.
226    28. More problems have arisen in unanchored patterns when CRLF is a valid line
227        break. For example, the unstudied pattern [\r\n]A does not match the string
228        "\r\nA" because change 7.0/46 below moves the current point on by two
229        characters after failing to match at the start. However, the pattern \nA
230        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
231        the same is true. There doesn't seem any very clean way out of this, but
232        what I have chosen to do makes the common cases work: PCRE now takes note
233        of whether there can be an explicit match for \r or \n anywhere in the
234        pattern, and if so, 7.0/46 no longer applies. As part of this change,
235        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
236        pattern has explicit CR or LF references.
238    29. Added (*CR) etc for changing newline setting at start of pattern.
241    Version 7.2 19-Jun-07
242  ---------------------  ---------------------
244   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,

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