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revision 143 by ph10, Mon Apr 2 10:08:14 2007 UTC revision 248 by ph10, Mon Sep 17 10:09:22 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 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    
64    Version 7.3 28-Aug-07
65    ---------------------
66    
67     1. In the rejigging of the build system that eventually resulted in 7.1, the
68        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
69        brackets there is not right, since it causes compilers to look for an
70        installed pcre.h, not the version that is in the source that is being
71        compiled (which of course may be different). I have changed it back to:
72    
73          #include "pcre.h"
74    
75        I have a vague recollection that the change was concerned with compiling in
76        different directories, but in the new build system, that is taken care of
77        by the VPATH setting the Makefile.
78    
79     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
80        when the subject happened to end in the byte 0x85 (e.g. if the last
81        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
82        characters but of course it shouldn't be taken as a newline when it is part
83        of another character. The bug was that, for an unlimited repeat of . in
84        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
85        characters when looking for a newline.
86    
87     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
88    
89     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
90        in debug output.
91    
92     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
93        long printing in the pcrecpp unittest when running under MinGW.
94    
95     6. ESC_K was left out of the EBCDIC table.
96    
97     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
98        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
99        limit also applies to "virtual nesting" when a pattern is recursive, and in
100        this case 1000 isn't so big. I have been able to remove this limit at the
101        expense of backing off one optimization in certain circumstances. Normally,
102        when pcre_exec() would call its internal match() function recursively and
103        immediately return the result unconditionally, it uses a "tail recursion"
104        feature to save stack. However, when a subpattern that can match an empty
105        string has an unlimited repetition quantifier, it no longer makes this
106        optimization. That gives it a stack frame in which to save the data for
107        checking that an empty string has been matched. Previously this was taken
108        from the 1000-entry workspace that had been reserved. So now there is no
109        explicit limit, but more stack is used.
110    
111     8. Applied Daniel's patches to solve problems with the import/export magic
112        syntax that is required for Windows, and which was going wrong for the
113        pcreposix and pcrecpp parts of the library. These were overlooked when this
114        problem was solved for the main library.
115    
116     9. There were some crude static tests to avoid integer overflow when computing
117        the size of patterns that contain repeated groups with explicit upper
118        limits. As the maximum quantifier is 65535, the maximum group length was
119        set at 30,000 so that the product of these two numbers did not overflow a
120        32-bit integer. However, it turns out that people want to use groups that
121        are longer than 30,000 bytes (though not repeat them that many times).
122        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
123        made it possible to implement the integer overflow checks in a much more
124        dynamic way, which I have now done. The artificial limitation on group
125        length has been removed - we now have only the limit on the total length of
126        the compiled pattern, which depends on the LINK_SIZE setting.
127    
128    10. Fixed a bug in the documentation for get/copy named substring when
129        duplicate names are permitted. If none of the named substrings are set, the
130        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
131        empty string.
132    
133    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
134        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
135        because the ] is interpreted as the first data character and the
136        terminating ] is not found. PCRE has been made compatible with Perl in this
137        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
138        cause memory overwriting.
139    
140    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
141        string has been matched (to stop an infinite loop). It was not recognizing
142        a conditional subpattern that could match an empty string if that
143        subpattern was within another subpattern. For example, it looped when
144        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
145        condition was not nested. This bug has been fixed.
146    
147    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
148        past the start of the subject in the presence of bytes with the top bit
149        set, for example "\x8aBCD".
150    
151    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
152        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
153    
154    14. Optimized (?!) to (*FAIL).
155    
156    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
157        This restricts code points to be within the range 0 to 0x10FFFF, excluding
158        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
159        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
160        does: it's just the validity check that is more restrictive.
161    
162    16. Inserted checks for integer overflows during escape sequence (backslash)
163        processing, and also fixed erroneous offset values for syntax errors during
164        backslash processing.
165    
166    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
167        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
168    
169    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
170        caused an overrun.
171    
172    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
173        something other than just ASCII characters) inside a group that had an
174        unlimited repeat caused a loop at compile time (while checking to see
175        whether the group could match an empty string).
176    
177    20. Debugging a pattern containing \p or \P could cause a crash. For example,
178        [\P{Any}] did so. (Error in the code for printing property names.)
179    
180    21. An orphan \E inside a character class could cause a crash.
181    
182    22. A repeated capturing bracket such as (A)? could cause a wild memory
183        reference during compilation.
184    
185    23. There are several functions in pcre_compile() that scan along a compiled
186        expression for various reasons (e.g. to see if it's fixed length for look
187        behind). There were bugs in these functions when a repeated \p or \P was
188        present in the pattern. These operators have additional parameters compared
189        with \d, etc, and these were not being taken into account when moving along
190        the compiled data. Specifically:
191    
192        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
193            length.
194    
195        (b) An item such as \pL+ within a repeated group could cause crashes or
196            loops.
197    
198        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
199            "reference to non-existent subpattern" error.
200    
201        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
202    
203    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
204        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
205    
206    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
207    
208    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
209        character were causing crashes (broken optimization).
210    
211    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
212        \p or \P) caused a compile-time loop.
213    
214    28. More problems have arisen in unanchored patterns when CRLF is a valid line
215        break. For example, the unstudied pattern [\r\n]A does not match the string
216        "\r\nA" because change 7.0/46 below moves the current point on by two
217        characters after failing to match at the start. However, the pattern \nA
218        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
219        the same is true. There doesn't seem any very clean way out of this, but
220        what I have chosen to do makes the common cases work: PCRE now takes note
221        of whether there can be an explicit match for \r or \n anywhere in the
222        pattern, and if so, 7.0/46 no longer applies. As part of this change,
223        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
224        pattern has explicit CR or LF references.
225    
226    29. Added (*CR) etc for changing newline setting at start of pattern.
227    
228    
229    Version 7.2 19-Jun-07
230    ---------------------
231    
232     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
233        which is apparently normally available under Windows.
234    
235     2. Re-jig the pcregrep tests with different newline settings in an attempt
236        to make them independent of the local environment's newline setting.
237    
238     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
239    
240     4. Some of the "internals" tests were previously cut out when the link size
241        was not 2, because the output contained actual offsets. The recent new
242        "Z" feature of pcretest means that these can be cut out, making the tests
243        usable with all link sizes.
244    
245     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
246        stack recursion. This gives a massive performance boost under BSD, but just
247        a small improvement under Linux. However, it saves one field in the frame
248        in all cases.
249    
250     6. Added more features from the forthcoming Perl 5.10:
251    
252        (a) (?-n) (where n is a string of digits) is a relative subroutine or
253            recursion call. It refers to the nth most recently opened parentheses.
254    
255        (b) (?+n) is also a relative subroutine call; it refers to the nth next
256            to be opened parentheses.
257    
258        (c) Conditions that refer to capturing parentheses can be specified
259            relatively, for example, (?(-2)... or (?(+3)...
260    
261        (d) \K resets the start of the current match so that everything before
262            is not part of it.
263    
264        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
265    
266        (f) \g{name} is another synonym - part of Perl 5.10's unification of
267            reference syntax.
268    
269        (g) (?| introduces a group in which the numbering of parentheses in each
270            alternative starts with the same number.
271    
272        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
273    
274     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
275        PCRE_INFO_JCHANGED.
276    
277     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
278        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
279        for detecting groups that can match an empty string.
280    
281     9. A pattern with a very large number of alternatives (more than several
282        hundred) was running out of internal workspace during the pre-compile
283        phase, where pcre_compile() figures out how much memory will be needed. A
284        bit of new cunning has reduced the workspace needed for groups with
285        alternatives. The 1000-alternative test pattern now uses 12 bytes of
286        workspace instead of running out of the 4096 that are available.
287    
288    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
289    
290    11. Applied patch from Google to remove an optimization that didn't quite work.
291        The report of the bug said:
292    
293          pcrecpp::RE("a*").FullMatch("aaa") matches, while
294          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
295          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
296    
297    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
298        it matched the wrong number of bytes.
299    
300    
301    Version 7.1 24-Apr-07
302  ---------------------  ---------------------
303    
304   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 136  Version 7.1 12-Mar-07 Line 433  Version 7.1 12-Mar-07
433      string at the end of a line did not allow for this case. They now check for      string at the end of a line did not allow for this case. They now check for
434      it specially.      it specially.
435    
436    20. pcretest is supposed to handle patterns and data of any length, by
437        extending its buffers when necessary. It was getting this wrong when the
438        buffer for a data line had to be extended.
439    
440    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
441        CRLF as a newline sequence.
442    
443    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
444        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
445        I have nevertheless tidied it up.
446    
447    23. Added some casts to kill warnings from HP-UX ia64 compiler.
448    
449    24. Added a man page for pcre-config.
450    
451    
452  Version 7.0 19-Dec-06  Version 7.0 19-Dec-06
453  ---------------------  ---------------------

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