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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    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 (where
36        different names are used).
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".
41    9.  When pcregrep was used with the --colour option, it missed the line ending
42        sequence off the lines that it output.
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:
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
56        Thanks to the folks working on Gregex for glib for this insight.
59    Version 7.3 28-Aug-07
60    ---------------------
62     1. In the rejigging of the build system that eventually resulted in 7.1, the
63        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
64        brackets there is not right, since it causes compilers to look for an
65        installed pcre.h, not the version that is in the source that is being
66        compiled (which of course may be different). I have changed it back to:
68          #include "pcre.h"
70        I have a vague recollection that the change was concerned with compiling in
71        different directories, but in the new build system, that is taken care of
72        by the VPATH setting the Makefile.
74     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
75        when the subject happened to end in the byte 0x85 (e.g. if the last
76        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
77        characters but of course it shouldn't be taken as a newline when it is part
78        of another character. The bug was that, for an unlimited repeat of . in
79        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
80        characters when looking for a newline.
82     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
84     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
85        in debug output.
87     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
88        long printing in the pcrecpp unittest when running under MinGW.
90     6. ESC_K was left out of the EBCDIC table.
92     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
93        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
94        limit also applies to "virtual nesting" when a pattern is recursive, and in
95        this case 1000 isn't so big. I have been able to remove this limit at the
96        expense of backing off one optimization in certain circumstances. Normally,
97        when pcre_exec() would call its internal match() function recursively and
98        immediately return the result unconditionally, it uses a "tail recursion"
99        feature to save stack. However, when a subpattern that can match an empty
100        string has an unlimited repetition quantifier, it no longer makes this
101        optimization. That gives it a stack frame in which to save the data for
102        checking that an empty string has been matched. Previously this was taken
103        from the 1000-entry workspace that had been reserved. So now there is no
104        explicit limit, but more stack is used.
106     8. Applied Daniel's patches to solve problems with the import/export magic
107        syntax that is required for Windows, and which was going wrong for the
108        pcreposix and pcrecpp parts of the library. These were overlooked when this
109        problem was solved for the main library.
111     9. There were some crude static tests to avoid integer overflow when computing
112        the size of patterns that contain repeated groups with explicit upper
113        limits. As the maximum quantifier is 65535, the maximum group length was
114        set at 30,000 so that the product of these two numbers did not overflow a
115        32-bit integer. However, it turns out that people want to use groups that
116        are longer than 30,000 bytes (though not repeat them that many times).
117        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
118        made it possible to implement the integer overflow checks in a much more
119        dynamic way, which I have now done. The artificial limitation on group
120        length has been removed - we now have only the limit on the total length of
121        the compiled pattern, which depends on the LINK_SIZE setting.
123    10. Fixed a bug in the documentation for get/copy named substring when
124        duplicate names are permitted. If none of the named substrings are set, the
125        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
126        empty string.
128    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
129        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
130        because the ] is interpreted as the first data character and the
131        terminating ] is not found. PCRE has been made compatible with Perl in this
132        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
133        cause memory overwriting.
135    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
136        string has been matched (to stop an infinite loop). It was not recognizing
137        a conditional subpattern that could match an empty string if that
138        subpattern was within another subpattern. For example, it looped when
139        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
140        condition was not nested. This bug has been fixed.
142    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
143        past the start of the subject in the presence of bytes with the top bit
144        set, for example "\x8aBCD".
146    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
147        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
149    14. Optimized (?!) to (*FAIL).
151    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
152        This restricts code points to be within the range 0 to 0x10FFFF, excluding
153        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
154        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
155        does: it's just the validity check that is more restrictive.
157    16. Inserted checks for integer overflows during escape sequence (backslash)
158        processing, and also fixed erroneous offset values for syntax errors during
159        backslash processing.
161    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
162        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
164    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
165        caused an overrun.
167    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
168        something other than just ASCII characters) inside a group that had an
169        unlimited repeat caused a loop at compile time (while checking to see
170        whether the group could match an empty string).
172    20. Debugging a pattern containing \p or \P could cause a crash. For example,
173        [\P{Any}] did so. (Error in the code for printing property names.)
175    21. An orphan \E inside a character class could cause a crash.
177    22. A repeated capturing bracket such as (A)? could cause a wild memory
178        reference during compilation.
180    23. There are several functions in pcre_compile() that scan along a compiled
181        expression for various reasons (e.g. to see if it's fixed length for look
182        behind). There were bugs in these functions when a repeated \p or \P was
183        present in the pattern. These operators have additional parameters compared
184        with \d, etc, and these were not being taken into account when moving along
185        the compiled data. Specifically:
187        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
188            length.
190        (b) An item such as \pL+ within a repeated group could cause crashes or
191            loops.
193        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
194            "reference to non-existent subpattern" error.
196        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
198    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
199        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
201    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
203    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
204        character were causing crashes (broken optimization).
206    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
207        \p or \P) caused a compile-time loop.
209    28. More problems have arisen in unanchored patterns when CRLF is a valid line
210        break. For example, the unstudied pattern [\r\n]A does not match the string
211        "\r\nA" because change 7.0/46 below moves the current point on by two
212        characters after failing to match at the start. However, the pattern \nA
213        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
214        the same is true. There doesn't seem any very clean way out of this, but
215        what I have chosen to do makes the common cases work: PCRE now takes note
216        of whether there can be an explicit match for \r or \n anywhere in the
217        pattern, and if so, 7.0/46 no longer applies. As part of this change,
218        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
219        pattern has explicit CR or LF references.
221    29. Added (*CR) etc for changing newline setting at start of pattern.
224    Version 7.2 19-Jun-07
225    ---------------------
227     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
228        which is apparently normally available under Windows.
230     2. Re-jig the pcregrep tests with different newline settings in an attempt
231        to make them independent of the local environment's newline setting.
233     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
235     4. Some of the "internals" tests were previously cut out when the link size
236        was not 2, because the output contained actual offsets. The recent new
237        "Z" feature of pcretest means that these can be cut out, making the tests
238        usable with all link sizes.
240     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
241        stack recursion. This gives a massive performance boost under BSD, but just
242        a small improvement under Linux. However, it saves one field in the frame
243        in all cases.
245     6. Added more features from the forthcoming Perl 5.10:
247        (a) (?-n) (where n is a string of digits) is a relative subroutine or
248            recursion call. It refers to the nth most recently opened parentheses.
250        (b) (?+n) is also a relative subroutine call; it refers to the nth next
251            to be opened parentheses.
253        (c) Conditions that refer to capturing parentheses can be specified
254            relatively, for example, (?(-2)... or (?(+3)...
256        (d) \K resets the start of the current match so that everything before
257            is not part of it.
259        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
261        (f) \g{name} is another synonym - part of Perl 5.10's unification of
262            reference syntax.
264        (g) (?| introduces a group in which the numbering of parentheses in each
265            alternative starts with the same number.
267        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
269     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
272     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
273        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
274        for detecting groups that can match an empty string.
276     9. A pattern with a very large number of alternatives (more than several
277        hundred) was running out of internal workspace during the pre-compile
278        phase, where pcre_compile() figures out how much memory will be needed. A
279        bit of new cunning has reduced the workspace needed for groups with
280        alternatives. The 1000-alternative test pattern now uses 12 bytes of
281        workspace instead of running out of the 4096 that are available.
283    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
285    11. Applied patch from Google to remove an optimization that didn't quite work.
286        The report of the bug said:
288          pcrecpp::RE("a*").FullMatch("aaa") matches, while
289          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
290          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
292    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
293        it matched the wrong number of bytes.
296  Version 7.1 24-Apr-07  Version 7.1 24-Apr-07
297  ---------------------  ---------------------

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