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revision 159 by ph10, Wed May 2 10:27:18 2007 UTC revision 268 by ph10, Thu Nov 15 10:28:09 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 7.2 01-May-07  Version 7.5 12-Nov-07
5    ---------------------
6    
7    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
8        values in parens when parsing an RE using the C++ wrapper."
9    
10    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
11        Characters greater than 255 were excluded from the class instead of being
12        included.
13    
14    3.  The same bug as (2) above applied to negated POSIX classes such as
15        [:^space:].
16    
17    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
18        defined or documented. It seems to have been a typo for PCRE_STATIC, so
19        I have changed it.
20    
21    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
22        first named subpattern) and a construct such as (?&a) would reference the
23        first named subpattern whose name started with "a" (in other words, the
24        length check was missing).
25    
26    
27    Version 7.4 21-Sep-07
28    ---------------------
29    
30    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
31        means that a class such as [\s] counted as "explicit reference to CR or
32        LF". That isn't really right - the whole point of the change was to try to
33        help when there was an actual mention of one of the two characters. So now
34        the change happens only if \r or \n (or a literal CR or LF) character is
35        encountered.
36    
37    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
38        of both had grown to the point where there were only 3 bits left.
39        Fortunately, there was spare space in the data structure, and so I have
40        moved the internal flags into a new 16-bit field to free up more option
41        bits.
42    
43    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
44        but did not set the internal JCHANGED flag - either of these is enough to
45        control the way the "get" function works - but the PCRE_INFO_JCHANGED
46        facility is supposed to tell if (?J) was ever used, so now (?J) at the
47        start sets both bits.
48    
49    4.  Added options (at build time, compile time, exec time) to change \R from
50        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
51    
52    5.  doc/pcresyntax.html was missing from the distribution.
53    
54    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
55        compatibility, even though it is no longer used.
56    
57    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
58        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
59        windows.h file is present (where different names are used). [This was
60        reversed later after testing - see 16 below.]
61    
62    8.  Changed all #include <config.h> to #include "config.h". There were also
63        some further <pcre.h> cases that I changed to "pcre.h".
64    
65    9.  When pcregrep was used with the --colour option, it missed the line ending
66        sequence off the lines that it output.
67    
68    10. It was pointed out to me that arrays of string pointers cause lots of
69        relocations when a shared library is dynamically loaded. A technique of
70        using a single long string with a table of offsets can drastically reduce
71        these. I have refactored PCRE in four places to do this. The result is
72        dramatic:
73    
74          Originally:                          290
75          After changing UCP table:            187
76          After changing error message table:   43
77          After changing table of "verbs"       36
78          After changing table of Posix names   22
79    
80        Thanks to the folks working on Gregex for glib for this insight.
81    
82    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
83        unicode-properties was also set.
84    
85    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
86    
87    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
88        checked only for CRLF.
89    
90    14. Added casts to pcretest.c to avoid compiler warnings.
91    
92    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
93    
94    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
95        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
96        entirely. This removes changes made in 7 above.
97    
98    17. The CMake files have been updated, and there is now more information about
99        building with CMake in the NON-UNIX-USE document.
100    
101    
102    Version 7.3 28-Aug-07
103    ---------------------
104    
105     1. In the rejigging of the build system that eventually resulted in 7.1, the
106        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
107        brackets there is not right, since it causes compilers to look for an
108        installed pcre.h, not the version that is in the source that is being
109        compiled (which of course may be different). I have changed it back to:
110    
111          #include "pcre.h"
112    
113        I have a vague recollection that the change was concerned with compiling in
114        different directories, but in the new build system, that is taken care of
115        by the VPATH setting the Makefile.
116    
117     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
118        when the subject happened to end in the byte 0x85 (e.g. if the last
119        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
120        characters but of course it shouldn't be taken as a newline when it is part
121        of another character. The bug was that, for an unlimited repeat of . in
122        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
123        characters when looking for a newline.
124    
125     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
126    
127     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
128        in debug output.
129    
130     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
131        long printing in the pcrecpp unittest when running under MinGW.
132    
133     6. ESC_K was left out of the EBCDIC table.
134    
135     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
136        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
137        limit also applies to "virtual nesting" when a pattern is recursive, and in
138        this case 1000 isn't so big. I have been able to remove this limit at the
139        expense of backing off one optimization in certain circumstances. Normally,
140        when pcre_exec() would call its internal match() function recursively and
141        immediately return the result unconditionally, it uses a "tail recursion"
142        feature to save stack. However, when a subpattern that can match an empty
143        string has an unlimited repetition quantifier, it no longer makes this
144        optimization. That gives it a stack frame in which to save the data for
145        checking that an empty string has been matched. Previously this was taken
146        from the 1000-entry workspace that had been reserved. So now there is no
147        explicit limit, but more stack is used.
148    
149     8. Applied Daniel's patches to solve problems with the import/export magic
150        syntax that is required for Windows, and which was going wrong for the
151        pcreposix and pcrecpp parts of the library. These were overlooked when this
152        problem was solved for the main library.
153    
154     9. There were some crude static tests to avoid integer overflow when computing
155        the size of patterns that contain repeated groups with explicit upper
156        limits. As the maximum quantifier is 65535, the maximum group length was
157        set at 30,000 so that the product of these two numbers did not overflow a
158        32-bit integer. However, it turns out that people want to use groups that
159        are longer than 30,000 bytes (though not repeat them that many times).
160        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
161        made it possible to implement the integer overflow checks in a much more
162        dynamic way, which I have now done. The artificial limitation on group
163        length has been removed - we now have only the limit on the total length of
164        the compiled pattern, which depends on the LINK_SIZE setting.
165    
166    10. Fixed a bug in the documentation for get/copy named substring when
167        duplicate names are permitted. If none of the named substrings are set, the
168        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
169        empty string.
170    
171    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
172        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
173        because the ] is interpreted as the first data character and the
174        terminating ] is not found. PCRE has been made compatible with Perl in this
175        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
176        cause memory overwriting.
177    
178    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
179        string has been matched (to stop an infinite loop). It was not recognizing
180        a conditional subpattern that could match an empty string if that
181        subpattern was within another subpattern. For example, it looped when
182        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
183        condition was not nested. This bug has been fixed.
184    
185    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
186        past the start of the subject in the presence of bytes with the top bit
187        set, for example "\x8aBCD".
188    
189    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
190        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
191    
192    14. Optimized (?!) to (*FAIL).
193    
194    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
195        This restricts code points to be within the range 0 to 0x10FFFF, excluding
196        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
197        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
198        does: it's just the validity check that is more restrictive.
199    
200    16. Inserted checks for integer overflows during escape sequence (backslash)
201        processing, and also fixed erroneous offset values for syntax errors during
202        backslash processing.
203    
204    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
205        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
206    
207    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
208        caused an overrun.
209    
210    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
211        something other than just ASCII characters) inside a group that had an
212        unlimited repeat caused a loop at compile time (while checking to see
213        whether the group could match an empty string).
214    
215    20. Debugging a pattern containing \p or \P could cause a crash. For example,
216        [\P{Any}] did so. (Error in the code for printing property names.)
217    
218    21. An orphan \E inside a character class could cause a crash.
219    
220    22. A repeated capturing bracket such as (A)? could cause a wild memory
221        reference during compilation.
222    
223    23. There are several functions in pcre_compile() that scan along a compiled
224        expression for various reasons (e.g. to see if it's fixed length for look
225        behind). There were bugs in these functions when a repeated \p or \P was
226        present in the pattern. These operators have additional parameters compared
227        with \d, etc, and these were not being taken into account when moving along
228        the compiled data. Specifically:
229    
230        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
231            length.
232    
233        (b) An item such as \pL+ within a repeated group could cause crashes or
234            loops.
235    
236        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
237            "reference to non-existent subpattern" error.
238    
239        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
240    
241    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
242        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
243    
244    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
245    
246    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
247        character were causing crashes (broken optimization).
248    
249    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
250        \p or \P) caused a compile-time loop.
251    
252    28. More problems have arisen in unanchored patterns when CRLF is a valid line
253        break. For example, the unstudied pattern [\r\n]A does not match the string
254        "\r\nA" because change 7.0/46 below moves the current point on by two
255        characters after failing to match at the start. However, the pattern \nA
256        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
257        the same is true. There doesn't seem any very clean way out of this, but
258        what I have chosen to do makes the common cases work: PCRE now takes note
259        of whether there can be an explicit match for \r or \n anywhere in the
260        pattern, and if so, 7.0/46 no longer applies. As part of this change,
261        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
262        pattern has explicit CR or LF references.
263    
264    29. Added (*CR) etc for changing newline setting at start of pattern.
265    
266    
267    Version 7.2 19-Jun-07
268  ---------------------  ---------------------
269    
270   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 272  Version 7.2 01-May-07
272    
273   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
274      to make them independent of the local environment's newline setting.      to make them independent of the local environment's newline setting.
275    
276   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.
277    
278     4. Some of the "internals" tests were previously cut out when the link size
279        was not 2, because the output contained actual offsets. The recent new
280        "Z" feature of pcretest means that these can be cut out, making the tests
281        usable with all link sizes.
282    
283     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
284        stack recursion. This gives a massive performance boost under BSD, but just
285        a small improvement under Linux. However, it saves one field in the frame
286        in all cases.
287    
288     6. Added more features from the forthcoming Perl 5.10:
289    
290        (a) (?-n) (where n is a string of digits) is a relative subroutine or
291            recursion call. It refers to the nth most recently opened parentheses.
292    
293        (b) (?+n) is also a relative subroutine call; it refers to the nth next
294            to be opened parentheses.
295    
296        (c) Conditions that refer to capturing parentheses can be specified
297            relatively, for example, (?(-2)... or (?(+3)...
298    
299        (d) \K resets the start of the current match so that everything before
300            is not part of it.
301    
302        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
303    
304        (f) \g{name} is another synonym - part of Perl 5.10's unification of
305            reference syntax.
306    
307        (g) (?| introduces a group in which the numbering of parentheses in each
308            alternative starts with the same number.
309    
310        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
311    
312     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
313        PCRE_INFO_JCHANGED.
314    
315     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
316        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
317        for detecting groups that can match an empty string.
318    
319     9. A pattern with a very large number of alternatives (more than several
320        hundred) was running out of internal workspace during the pre-compile
321        phase, where pcre_compile() figures out how much memory will be needed. A
322        bit of new cunning has reduced the workspace needed for groups with
323        alternatives. The 1000-alternative test pattern now uses 12 bytes of
324        workspace instead of running out of the 4096 that are available.
325    
326    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
327    
328    11. Applied patch from Google to remove an optimization that didn't quite work.
329        The report of the bug said:
330    
331          pcrecpp::RE("a*").FullMatch("aaa") matches, while
332          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
333          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
334    
335    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
336        it matched the wrong number of bytes.
337    
338    
339  Version 7.1 24-Apr-07  Version 7.1 24-Apr-07

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