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revision 587 by ph10, Fri Jan 14 19:01:25 2011 UTC revision 691 by ph10, Sun Sep 11 14:31:21 2011 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.12 12-Jan-2011  Version 8.20 12-Sep-2011
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. This bug also affected patterns with classes that started
11       with full stops.
12    
13    2. If a pattern such as /(a)b|ac/ is matched against "ac", there is no captured
14       substring, but while checking the failing first alternative, substring 1 is
15       temporarily captured. If the output vector supplied to pcre_exec() was not
16       big enough for this capture, the yield of the function was still zero
17       ("insufficient space for captured substrings"). This cannot be totally fixed
18       without adding another stack variable, which seems a lot of expense for a
19       edge case. However, I have improved the situation in cases such as
20       /(a)(b)x|abc/ matched against "abc", where the return code indicates that
21       fewer than the maximum number of slots in the ovector have been set.
22    
23    3. Related to (2) above: when there are more back references in a pattern than
24       slots in the output vector, pcre_exec() uses temporary memory during
25       matching, and copies in the captures as far as possible afterwards. It was
26       using the entire output vector, but this conflicts with the specification
27       that only 2/3 is used for passing back captured substrings. Now it uses only
28       the first 2/3, for compatibility. This is, of course, another edge case.
29    
30    4. Zoltan Herczeg's just-in-time compiler support has been integrated into the
31       main code base, and can be used by building with --enable-jit. When this is
32       done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
33       runtime --no-jit option is given.
34    
35    5. When the number of matches in a pcre_dfa_exec() run exactly filled the
36       ovector, the return from the function was zero, implying that there were
37       other matches that did not fit. The correct "exactly full" value is now
38       returned.
39    
40    6. If a subpattern that was called recursively or as a subroutine contained
41       (*PRUNE) or any other control that caused it to give a non-standard return,
42       invalid errors such as "Error -26 (nested recursion at the same subject
43       position)" or even infinite loops could occur.
44    
45    
46    Version 8.13 16-Aug-2011
47    ------------------------
48    
49    1.  The Unicode data tables have been updated to Unicode 6.0.0.
50    
51    2.  Two minor typos in pcre_internal.h have been fixed.
52    
53    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
54        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
55        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
56    
57    4.  There were a number of related bugs in the code for matching backrefences
58        caselessly in UTF-8 mode when codes for the characters concerned were
59        different numbers of bytes. For example, U+023A and U+2C65 are an upper
60        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
61        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
62        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
63        2-byte code at the end of the subject (it thought there wasn't enough data
64        left).
65    
66    5.  Comprehensive information about what went wrong is now returned by
67        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
68        as the output vector has at least 2 elements. The offset of the start of
69        the failing character and a reason code are placed in the vector.
70    
71    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
72        now returned is for the first byte of the failing character, instead of the
73        last byte inspected. This is an incompatible change, but I hope it is small
74        enough not to be a problem. It makes the returned offset consistent with
75        pcre_exec() and pcre_dfa_exec().
76    
77    7.  pcretest now gives a text phrase as well as the error number when
78        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
79        failure, the offset and reason code are output.
80    
81    8.  When \R was used with a maximizing quantifier it failed to skip backwards
82        over a \r\n pair if the subsequent match failed. Instead, it just skipped
83        back over a single character (\n). This seems wrong (because it treated the
84        two characters as a single entity when going forwards), conflicts with the
85        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
86        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
87        has been changed.
88    
89    9.  Some internal refactoring has changed the processing so that the handling
90        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
91        time (the PCRE_DOTALL option was changed this way some time ago: version
92        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
93        which was always a bit of a fudge. It also means that there is one less
94        argument for the match() function, which reduces its stack requirements
95        slightly. This change also fixes an incompatibility with Perl: the pattern
96        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
97    
98    10. More internal refactoring has drastically reduced the number of recursive
99        calls to match() for possessively repeated groups such as (abc)++ when
100        using pcre_exec().
101    
102    11. While implementing 10, a number of bugs in the handling of groups were
103        discovered and fixed:
104    
105        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
106        (a|)*(?1) gave a compile-time internal error.
107        ((a|)+)+  did not notice that the outer group could match an empty string.
108        (^a|^)+   was not marked as anchored.
109        (.*a|.*)+ was not marked as matching at start or after a newline.
110    
111    12. Yet more internal refactoring has removed another argument from the match()
112        function. Special calls to this function are now indicated by setting a
113        value in a variable in the "match data" data block.
114    
115    13. Be more explicit in pcre_study() instead of relying on "default" for
116        opcodes that mean there is no starting character; this means that when new
117        ones are added and accidentally left out of pcre_study(), testing should
118        pick them up.
119    
120    14. The -s option of pcretest has been documented for ages as being an old
121        synonym of -m (show memory usage). I have changed it to mean "force study
122        for every regex", that is, assume /S for every regex. This is similar to -i
123        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
124        using it. It makes it easier to run collections of tests with and without
125        study enabled, and thereby test pcre_study() more easily. All the standard
126        tests are now run with and without -s (but some patterns can be marked as
127        "never study" - see 20 below).
128    
129    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
130        restoration of the capturing data to the outer values was not happening
131        correctly.
132    
133    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
134        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
135        pattern had matched an empty string, and so incorrectly returned a no
136        match.
137    
138    17. There was optimizing code for the last branch of non-capturing parentheses,
139        and also for the obeyed branch of a conditional subexpression, which used
140        tail recursion to cut down on stack usage. Unfortunately, now that there is
141        the possibility of (*THEN) occurring in these branches, tail recursion is
142        no longer possible because the return has to be checked for (*THEN). These
143        two optimizations have therefore been removed.
144    
145    18. If a pattern containing \R was studied, it was assumed that \R always
146        matched two bytes, thus causing the minimum subject length to be
147        incorrectly computed because \R can also match just one byte.
148    
149    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
150        was incorrectly computed.
151    
152    20. If /S is present twice on a test pattern in pcretest input, it now
153        *disables* studying, thereby overriding the use of -s on the command line
154        (see 14 above). This is necessary for one or two tests to keep the output
155        identical in both cases.
156    
157    21. When (*ACCEPT) was used in an assertion that matched an empty string and
158        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
159    
160    22. When an atomic group that contained a capturing parenthesis was
161        successfully matched, but the branch in which it appeared failed, the
162        capturing was not being forgotten if a higher numbered group was later
163        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
164        group 1 to "a", when in fact it should be unset. This applied to multi-
165        branched capturing and non-capturing groups, repeated or not, and also to
166        positive assertions (capturing in negative assertions does not happen
167        in PCRE) and also to nested atomic groups.
168    
169    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
170        subject after a captured substring, to make it easier to tell which of a
171        number of identical substrings has been captured.
172    
173    24. The way atomic groups are processed by pcre_exec() has been changed so that
174        if they are repeated, backtracking one repetition now resets captured
175        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
176        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
177        "aaa". Previously, it would have been "a". As part of this code
178        refactoring, the way recursive calls are handled has also been changed.
179    
180    25. If an assertion condition captured any substrings, they were not passed
181        back unless some other capturing happened later. For example, if
182        (?(?=(a))a) was matched against "a", no capturing was returned.
183    
184    26. When studying a pattern that contained subroutine calls or assertions,
185        the code for finding the minimum length of a possible match was handling
186        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
187        group 1 called group 2 while simultaneously a separate group 2 called group
188        1). A stack overflow occurred in this case. I have fixed this by limiting
189        the recursion depth to 10.
190    
191    27. Updated RunTest.bat in the distribution to the version supplied by Tom
192        Fortmann. This supports explicit test numbers on the command line, and has
193        argument validation and error reporting.
194    
195    28. An instance of \X with an unlimited repeat could fail if at any point the
196        first character it looked at was a mark character.
197    
198    29. Some minor code refactoring concerning Unicode properties and scripts
199        should reduce the stack requirement of match() slightly.
200    
201    30. Added the '=' option to pcretest to check the setting of unused capturing
202        slots at the end of the pattern, which are documented as being -1, but are
203        not included in the return count.
204    
205    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
206        compiled something random. Now it gives a compile-time error (as does
207        Perl).
208    
209    32. A *MARK encountered during the processing of a positive assertion is now
210        recorded and passed back (compatible with Perl).
211    
212    33. If --only-matching or --colour was set on a pcregrep call whose pattern
213        had alternative anchored branches, the search for a second match in a line
214        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
215        matched the line "0102" twice. The same bug affected patterns that started
216        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
217        twice.
218    
219    34. Previously, PCRE did not allow quantification of assertions. However, Perl
220        does, and because of capturing effects, quantifying parenthesized
221        assertions may at times be useful. Quantifiers are now allowed for
222        parenthesized assertions.
223    
224    35. A minor code tidy in pcre_compile() when checking options for \R usage.
225    
226    36. \g was being checked for fancy things in a character class, when it should
227        just be a literal "g".
228    
229    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
230        appearance of a nested POSIX class supersedes an apparent external class.
231        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
232        unescaped square brackets may also appear as part of class names. For
233        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
234        more like Perl. (But see 8.20/1 above.)
235    
236    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
237        was because it thought it was \N{name}, which is not supported).
238    
239    39. Add minix to OS list not supporting the -S option in pcretest.
240    
241    40. PCRE tries to detect cases of infinite recursion at compile time, but it
242        cannot analyze patterns in sufficient detail to catch mutual recursions
243        such as ((?1))((?2)). There is now a runtime test that gives an error if a
244        subgroup is called recursively as a subpattern for a second time at the
245        same position in the subject string. In previous releases this might have
246        been caught by the recursion limit, or it might have run out of stack.
247    
248    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
249        happen only once. PCRE was, however incorrectly giving a compile time error
250        "recursive call could loop indefinitely" because it cannot analyze the
251        pattern in sufficient detail. The compile time test no longer happens when
252        PCRE is compiling a conditional subpattern, but actual runaway loops are
253        now caught at runtime (see 40 above).
254    
255    42. It seems that Perl allows any characters other than a closing parenthesis
256        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
257        has been changed to be the same.
258    
259    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
260        as not to get warnings when autogen.sh is called. Also changed
261        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
262    
263    44. To help people who use pcregrep to scan files containing exceedingly long
264        lines, the following changes have been made:
265    
266        (a) The default value of the buffer size parameter has been increased from
267            8K to 20K. (The actual buffer used is three times this size.)
268    
269        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
270            PCRE is built.
271    
272        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
273            to be set at run time.
274    
275        (d) Numerical values in pcregrep options can be followed by K or M, for
276            example --buffer-size=50K.
277    
278        (e) If a line being scanned overflows pcregrep's buffer, an error is now
279            given and the return code is set to 2.
280    
281    45. Add a pointer to the latest mark to the callout data block.
282    
283    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
284        partial match of an empty string instead of no match. This was specific to
285        the use of ".".
286    
287    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
288        complete match instead of a partial match. This bug was dependent on both
289        the PCRE_UTF8 and PCRE_DOTALL options being set.
290    
291    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
292        starting byte set, because \b was not being ignored.
293    
294    
295    Version 8.12 15-Jan-2011
296  ------------------------  ------------------------
297    
298  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
299      checks for such things as part of the documentation building process.      checks for such things as part of the documentation building process.
300    
301  2.  On a big-endian 64-bit system, pcregrep did not correctly process the  2.  On a big-endian 64-bit system, pcregrep did not correctly process the
302      --match-limit and --recursion-limit options (added for 8.11). In      --match-limit and --recursion-limit options (added for 8.11). In
303      particular, this made one of the standard tests crash. (The integer value      particular, this made one of the standard tests fail. (The integer value
304      went into the wrong half of a long int.)      went into the wrong half of a long int.)
305    
306  3.  If the --colour option was given to pcregrep with -v (invert match), it  3.  If the --colour option was given to pcregrep with -v (invert match), it
307      did strange things, either producing crazy output, or crashing. It should,      did strange things, either producing crazy output, or crashing. It should,
308      of course, ignore a request for colour when reporting lines that do not      of course, ignore a request for colour when reporting lines that do not
309      match.      match.
310    
311  4.  Another pcregrep bug caused similar problems if --colour was specified with  4.  Another pcregrep bug caused similar problems if --colour was specified with
312      -M (multiline) and the pattern match finished with a line ending.      -M (multiline) and the pattern match finished with a line ending.
313    
314  5.  In pcregrep, when a pattern that ended with a literal newline sequence was  5.  In pcregrep, when a pattern that ended with a literal newline sequence was
315      matched in multiline mode, the following line was shown as part of the      matched in multiline mode, the following line was shown as part of the
316      match. This seems wrong, so I have changed it.      match. This seems wrong, so I have changed it.
317    
318  6.  If pcregrep was compiled under Windows, there was a reference to the  6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
319        the check for further matches in the same line (so they could be coloured)
320        to overrun the end of the current line. If another match was found, it was
321        incorrectly shown (and then shown again when found in the next line).
322    
323    7.  If pcregrep was compiled under Windows, there was a reference to the
324      function pcregrep_exit() before it was defined. I am assuming this was      function pcregrep_exit() before it was defined. I am assuming this was
325      the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was      the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
326      reported by a user. I've moved the definition above the reference.      reported by a user. I've moved the definition above the reference.
327    
328    
329  Version 8.11 10-Dec-2010  Version 8.11 10-Dec-2010
330  ------------------------  ------------------------

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