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revision 583 by ph10, Tue Jan 11 16:49:55 2011 UTC revision 681 by ph10, Tue Sep 6 09:16:32 2011 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.12 11-Jan-2011  Version 8.20
5    ------------
6    
7    1. Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
8       a POSIX class. After further experiments with Perl, which convinced me that
9       Perl has bugs and confusions, a closing square bracket is no longer allowed
10       in a POSIX name.
11    
12    2. If a pattern such as /(a)b|ac/ is matched against "ac", there is no captured
13       substring, but while checking the failing first alternative, substring 1 is
14       temporarily captured. If the output vector supplied to pcre_exec() was not
15       big enough for this capture, the yield of the function was still zero
16       ("insufficient space for captured substrings"). This cannot be totally fixed
17       without adding another stack variable, which seems a lot of expense for a
18       edge case. However, I have improved the situation in cases such as
19       /(a)(b)x|abc/ matched against "abc", where the return code indicates that
20       fewer than the maximum number of slots in the ovector have been set.
21    
22    3. Related to (2) above: when there are more back references in a pattern than
23       slots in the output vector, pcre_exec() uses temporary memory during
24       matching, and copies in the captures as far as possible afterwards. It was
25       using the entire output vector, but this conflicts with the specification
26       that only 2/3 is used for passing back captured substrings. Now it uses only
27       the first 2/3, for compatibility. This is, of course, another edge case.
28    
29    4. Zoltan Herczeg's just-in-time compiler support has been integrated into the
30       main code base, and can be used by building with --enable-jit.
31    
32    5. When the number of matches in a pcre_dfa_exec() run exactly filled the
33       ovector, the return from the function was zero, implying that there were
34       other matches that did not fit. The correct "exactly full" value is now
35       returned.
36    
37    6. If a subpattern that was called recursively or as a subroutine contained
38       (*PRUNE) or any other control that caused it to give a non-standard return,
39       invalid errors such as "Error -26 (nested recursion at the same subject
40       position)" or even infinite loops could occur.
41    
42    
43    Version 8.13 16-Aug-2011
44    ------------------------
45    
46    1.  The Unicode data tables have been updated to Unicode 6.0.0.
47    
48    2.  Two minor typos in pcre_internal.h have been fixed.
49    
50    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
51        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
52        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
53    
54    4.  There were a number of related bugs in the code for matching backrefences
55        caselessly in UTF-8 mode when codes for the characters concerned were
56        different numbers of bytes. For example, U+023A and U+2C65 are an upper
57        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
58        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
59        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
60        2-byte code at the end of the subject (it thought there wasn't enough data
61        left).
62    
63    5.  Comprehensive information about what went wrong is now returned by
64        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
65        as the output vector has at least 2 elements. The offset of the start of
66        the failing character and a reason code are placed in the vector.
67    
68    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
69        now returned is for the first byte of the failing character, instead of the
70        last byte inspected. This is an incompatible change, but I hope it is small
71        enough not to be a problem. It makes the returned offset consistent with
72        pcre_exec() and pcre_dfa_exec().
73    
74    7.  pcretest now gives a text phrase as well as the error number when
75        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
76        failure, the offset and reason code are output.
77    
78    8.  When \R was used with a maximizing quantifier it failed to skip backwards
79        over a \r\n pair if the subsequent match failed. Instead, it just skipped
80        back over a single character (\n). This seems wrong (because it treated the
81        two characters as a single entity when going forwards), conflicts with the
82        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
83        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
84        has been changed.
85    
86    9.  Some internal refactoring has changed the processing so that the handling
87        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
88        time (the PCRE_DOTALL option was changed this way some time ago: version
89        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
90        which was always a bit of a fudge. It also means that there is one less
91        argument for the match() function, which reduces its stack requirements
92        slightly. This change also fixes an incompatibility with Perl: the pattern
93        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
94    
95    10. More internal refactoring has drastically reduced the number of recursive
96        calls to match() for possessively repeated groups such as (abc)++ when
97        using pcre_exec().
98    
99    11. While implementing 10, a number of bugs in the handling of groups were
100        discovered and fixed:
101    
102        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
103        (a|)*(?1) gave a compile-time internal error.
104        ((a|)+)+  did not notice that the outer group could match an empty string.
105        (^a|^)+   was not marked as anchored.
106        (.*a|.*)+ was not marked as matching at start or after a newline.
107    
108    12. Yet more internal refactoring has removed another argument from the match()
109        function. Special calls to this function are now indicated by setting a
110        value in a variable in the "match data" data block.
111    
112    13. Be more explicit in pcre_study() instead of relying on "default" for
113        opcodes that mean there is no starting character; this means that when new
114        ones are added and accidentally left out of pcre_study(), testing should
115        pick them up.
116    
117    14. The -s option of pcretest has been documented for ages as being an old
118        synonym of -m (show memory usage). I have changed it to mean "force study
119        for every regex", that is, assume /S for every regex. This is similar to -i
120        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
121        using it. It makes it easier to run collections of tests with and without
122        study enabled, and thereby test pcre_study() more easily. All the standard
123        tests are now run with and without -s (but some patterns can be marked as
124        "never study" - see 20 below).
125    
126    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
127        restoration of the capturing data to the outer values was not happening
128        correctly.
129    
130    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
131        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
132        pattern had matched an empty string, and so incorrectly returned a no
133        match.
134    
135    17. There was optimizing code for the last branch of non-capturing parentheses,
136        and also for the obeyed branch of a conditional subexpression, which used
137        tail recursion to cut down on stack usage. Unfortunately, now that there is
138        the possibility of (*THEN) occurring in these branches, tail recursion is
139        no longer possible because the return has to be checked for (*THEN). These
140        two optimizations have therefore been removed.
141    
142    18. If a pattern containing \R was studied, it was assumed that \R always
143        matched two bytes, thus causing the minimum subject length to be
144        incorrectly computed because \R can also match just one byte.
145    
146    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
147        was incorrectly computed.
148    
149    20. If /S is present twice on a test pattern in pcretest input, it now
150        *disables* studying, thereby overriding the use of -s on the command line
151        (see 14 above). This is necessary for one or two tests to keep the output
152        identical in both cases.
153    
154    21. When (*ACCEPT) was used in an assertion that matched an empty string and
155        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
156    
157    22. When an atomic group that contained a capturing parenthesis was
158        successfully matched, but the branch in which it appeared failed, the
159        capturing was not being forgotten if a higher numbered group was later
160        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
161        group 1 to "a", when in fact it should be unset. This applied to multi-
162        branched capturing and non-capturing groups, repeated or not, and also to
163        positive assertions (capturing in negative assertions does not happen
164        in PCRE) and also to nested atomic groups.
165    
166    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
167        subject after a captured substring, to make it easier to tell which of a
168        number of identical substrings has been captured.
169    
170    24. The way atomic groups are processed by pcre_exec() has been changed so that
171        if they are repeated, backtracking one repetition now resets captured
172        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
173        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
174        "aaa". Previously, it would have been "a". As part of this code
175        refactoring, the way recursive calls are handled has also been changed.
176    
177    25. If an assertion condition captured any substrings, they were not passed
178        back unless some other capturing happened later. For example, if
179        (?(?=(a))a) was matched against "a", no capturing was returned.
180    
181    26. When studying a pattern that contained subroutine calls or assertions,
182        the code for finding the minimum length of a possible match was handling
183        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
184        group 1 called group 2 while simultaneously a separate group 2 called group
185        1). A stack overflow occurred in this case. I have fixed this by limiting
186        the recursion depth to 10.
187    
188    27. Updated RunTest.bat in the distribution to the version supplied by Tom
189        Fortmann. This supports explicit test numbers on the command line, and has
190        argument validation and error reporting.
191    
192    28. An instance of \X with an unlimited repeat could fail if at any point the
193        first character it looked at was a mark character.
194    
195    29. Some minor code refactoring concerning Unicode properties and scripts
196        should reduce the stack requirement of match() slightly.
197    
198    30. Added the '=' option to pcretest to check the setting of unused capturing
199        slots at the end of the pattern, which are documented as being -1, but are
200        not included in the return count.
201    
202    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
203        compiled something random. Now it gives a compile-time error (as does
204        Perl).
205    
206    32. A *MARK encountered during the processing of a positive assertion is now
207        recorded and passed back (compatible with Perl).
208    
209    33. If --only-matching or --colour was set on a pcregrep call whose pattern
210        had alternative anchored branches, the search for a second match in a line
211        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
212        matched the line "0102" twice. The same bug affected patterns that started
213        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
214        twice.
215    
216    34. Previously, PCRE did not allow quantification of assertions. However, Perl
217        does, and because of capturing effects, quantifying parenthesized
218        assertions may at times be useful. Quantifiers are now allowed for
219        parenthesized assertions.
220    
221    35. A minor code tidy in pcre_compile() when checking options for \R usage.
222    
223    36. \g was being checked for fancy things in a character class, when it should
224        just be a literal "g".
225    
226    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
227        appearance of a nested POSIX class supersedes an apparent external class.
228        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
229        unescaped square brackets may also appear as part of class names. For
230        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
231        more like Perl. (But see 8.20/1 above.)
232    
233    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
234        was because it thought it was \N{name}, which is not supported).
235    
236    39. Add minix to OS list not supporting the -S option in pcretest.
237    
238    40. PCRE tries to detect cases of infinite recursion at compile time, but it
239        cannot analyze patterns in sufficient detail to catch mutual recursions
240        such as ((?1))((?2)). There is now a runtime test that gives an error if a
241        subgroup is called recursively as a subpattern for a second time at the
242        same position in the subject string. In previous releases this might have
243        been caught by the recursion limit, or it might have run out of stack.
244    
245    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
246        happen only once. PCRE was, however incorrectly giving a compile time error
247        "recursive call could loop indefinitely" because it cannot analyze the
248        pattern in sufficient detail. The compile time test no longer happens when
249        PCRE is compiling a conditional subpattern, but actual runaway loops are
250        now caught at runtime (see 40 above).
251    
252    42. It seems that Perl allows any characters other than a closing parenthesis
253        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
254        has been changed to be the same.
255    
256    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
257        as not to get warnings when autogen.sh is called. Also changed
258        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
259    
260    44. To help people who use pcregrep to scan files containing exceedingly long
261        lines, the following changes have been made:
262    
263        (a) The default value of the buffer size parameter has been increased from
264            8K to 20K. (The actual buffer used is three times this size.)
265    
266        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
267            PCRE is built.
268    
269        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
270            to be set at run time.
271    
272        (d) Numerical values in pcregrep options can be followed by K or M, for
273            example --buffer-size=50K.
274    
275        (e) If a line being scanned overflows pcregrep's buffer, an error is now
276            given and the return code is set to 2.
277    
278    45. Add a pointer to the latest mark to the callout data block.
279    
280    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
281        partial match of an empty string instead of no match. This was specific to
282        the use of ".".
283    
284    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
285        complete match instead of a partial match. This bug was dependent on both
286        the PCRE_UTF8 and PCRE_DOTALL options being set.
287    
288    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
289        starting byte set, because \b was not being ignored.
290    
291    
292    Version 8.12 15-Jan-2011
293  ------------------------  ------------------------
294    
295  1.  Fixed some typos in the markup of the man pages, and wrote a script that  1.  Fixed some typos in the markup of the man pages, and wrote a script that
296      checks for such things as part of the documentation building process.      checks for such things as part of the documentation building process.
297    
298    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
299        --match-limit and --recursion-limit options (added for 8.11). In
300        particular, this made one of the standard tests fail. (The integer value
301        went into the wrong half of a long int.)
302    
303    3.  If the --colour option was given to pcregrep with -v (invert match), it
304        did strange things, either producing crazy output, or crashing. It should,
305        of course, ignore a request for colour when reporting lines that do not
306        match.
307    
308    4.  Another pcregrep bug caused similar problems if --colour was specified with
309        -M (multiline) and the pattern match finished with a line ending.
310    
311    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
312        matched in multiline mode, the following line was shown as part of the
313        match. This seems wrong, so I have changed it.
314    
315    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
316        the check for further matches in the same line (so they could be coloured)
317        to overrun the end of the current line. If another match was found, it was
318        incorrectly shown (and then shown again when found in the next line).
319    
320    7.  If pcregrep was compiled under Windows, there was a reference to the
321        function pcregrep_exit() before it was defined. I am assuming this was
322        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
323        reported by a user. I've moved the definition above the reference.
324    
325    
326  Version 8.11 10-Dec-2010  Version 8.11 10-Dec-2010
327  ------------------------  ------------------------

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