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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.13 30-Apr-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
14        captured substring, but while checking the failing first alternative,
15        substring 1 is temporarily captured. If the output vector supplied to
16        pcre_exec() was not big enough for this capture, the yield of the function
17        was still zero ("insufficient space for captured substrings"). This cannot
18        be totally fixed without adding another stack variable, which seems a lot
19        of expense for a edge case. However, I have improved the situation in cases
20        such as /(a)(b)x|abc/ matched against "abc", where the return code
21        indicates that fewer than the maximum number of slots in the ovector have
22        been set.
23    
24    3.  Related to (2) above: when there are more back references in a pattern than
25        slots in the output vector, pcre_exec() uses temporary memory during
26        matching, and copies in the captures as far as possible afterwards. It was
27        using the entire output vector, but this conflicts with the specification
28        that only 2/3 is used for passing back captured substrings. Now it uses
29        only the first 2/3, for compatibility. This is, of course, another edge
30        case.
31    
32    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
33        main code base, and can be used by building with --enable-jit. When this is
34        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
35        runtime --no-jit option is given.
36    
37    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
38        ovector, the return from the function was zero, implying that there were
39        other matches that did not fit. The correct "exactly full" value is now
40        returned.
41    
42    6.  If a subpattern that was called recursively or as a subroutine contained
43        (*PRUNE) or any other control that caused it to give a non-standard return,
44        invalid errors such as "Error -26 (nested recursion at the same subject
45        position)" or even infinite loops could occur.
46    
47    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
48        computing the minimum length on reaching *ACCEPT, and so ended up with the
49        wrong value of 1 rather than 0. Further investigation indicates that
50        computing a minimum subject length in the presence of *ACCEPT is difficult
51        (think back references, subroutine calls), and so I have changed the code
52        so that no minimum is registered for a pattern that contains *ACCEPT.
53    
54    8.  If (*THEN) was present in the first (true) branch of a conditional group,
55        it was not handled as intended.
56    
57    9.  Replaced RunTest.bat with the much improved version provided by Sheri
58        Pierce.
59    
60    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
61        the first byte in a match must be "a".
62    
63    11. Change 17 for 8.13 increased the recursion depth for patterns like
64        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
65        pattern contains any instances of (*THEN). If it does not, the old
66        optimizations are restored. It would be nice to do this on a per-group
67        basis, but at the moment that is not feasible.
68    
69    
70    Version 8.13 16-Aug-2011
71  ------------------------  ------------------------
72    
73  1.  The Unicode data tables have been updated to Unicode 6.0.0.  1.  The Unicode data tables have been updated to Unicode 6.0.0.
74    
75    2.  Two minor typos in pcre_internal.h have been fixed.
76    
77    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
78        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
79        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
80    
81    4.  There were a number of related bugs in the code for matching backrefences
82        caselessly in UTF-8 mode when codes for the characters concerned were
83        different numbers of bytes. For example, U+023A and U+2C65 are an upper
84        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
85        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
86        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
87        2-byte code at the end of the subject (it thought there wasn't enough data
88        left).
89    
90    5.  Comprehensive information about what went wrong is now returned by
91        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
92        as the output vector has at least 2 elements. The offset of the start of
93        the failing character and a reason code are placed in the vector.
94    
95    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
96        now returned is for the first byte of the failing character, instead of the
97        last byte inspected. This is an incompatible change, but I hope it is small
98        enough not to be a problem. It makes the returned offset consistent with
99        pcre_exec() and pcre_dfa_exec().
100    
101    7.  pcretest now gives a text phrase as well as the error number when
102        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
103        failure, the offset and reason code are output.
104    
105    8.  When \R was used with a maximizing quantifier it failed to skip backwards
106        over a \r\n pair if the subsequent match failed. Instead, it just skipped
107        back over a single character (\n). This seems wrong (because it treated the
108        two characters as a single entity when going forwards), conflicts with the
109        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
110        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
111        has been changed.
112    
113    9.  Some internal refactoring has changed the processing so that the handling
114        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
115        time (the PCRE_DOTALL option was changed this way some time ago: version
116        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
117        which was always a bit of a fudge. It also means that there is one less
118        argument for the match() function, which reduces its stack requirements
119        slightly. This change also fixes an incompatibility with Perl: the pattern
120        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
121    
122    10. More internal refactoring has drastically reduced the number of recursive
123        calls to match() for possessively repeated groups such as (abc)++ when
124        using pcre_exec().
125    
126    11. While implementing 10, a number of bugs in the handling of groups were
127        discovered and fixed:
128    
129        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
130        (a|)*(?1) gave a compile-time internal error.
131        ((a|)+)+  did not notice that the outer group could match an empty string.
132        (^a|^)+   was not marked as anchored.
133        (.*a|.*)+ was not marked as matching at start or after a newline.
134    
135    12. Yet more internal refactoring has removed another argument from the match()
136        function. Special calls to this function are now indicated by setting a
137        value in a variable in the "match data" data block.
138    
139    13. Be more explicit in pcre_study() instead of relying on "default" for
140        opcodes that mean there is no starting character; this means that when new
141        ones are added and accidentally left out of pcre_study(), testing should
142        pick them up.
143    
144    14. The -s option of pcretest has been documented for ages as being an old
145        synonym of -m (show memory usage). I have changed it to mean "force study
146        for every regex", that is, assume /S for every regex. This is similar to -i
147        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
148        using it. It makes it easier to run collections of tests with and without
149        study enabled, and thereby test pcre_study() more easily. All the standard
150        tests are now run with and without -s (but some patterns can be marked as
151        "never study" - see 20 below).
152    
153    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
154        restoration of the capturing data to the outer values was not happening
155        correctly.
156    
157    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
158        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
159        pattern had matched an empty string, and so incorrectly returned a no
160        match.
161    
162    17. There was optimizing code for the last branch of non-capturing parentheses,
163        and also for the obeyed branch of a conditional subexpression, which used
164        tail recursion to cut down on stack usage. Unfortunately, now that there is
165        the possibility of (*THEN) occurring in these branches, tail recursion is
166        no longer possible because the return has to be checked for (*THEN). These
167        two optimizations have therefore been removed. [But see 8.20/11 above.]
168    
169    18. If a pattern containing \R was studied, it was assumed that \R always
170        matched two bytes, thus causing the minimum subject length to be
171        incorrectly computed because \R can also match just one byte.
172    
173    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
174        was incorrectly computed.
175    
176    20. If /S is present twice on a test pattern in pcretest input, it now
177        *disables* studying, thereby overriding the use of -s on the command line
178        (see 14 above). This is necessary for one or two tests to keep the output
179        identical in both cases.
180    
181    21. When (*ACCEPT) was used in an assertion that matched an empty string and
182        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
183    
184    22. When an atomic group that contained a capturing parenthesis was
185        successfully matched, but the branch in which it appeared failed, the
186        capturing was not being forgotten if a higher numbered group was later
187        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
188        group 1 to "a", when in fact it should be unset. This applied to multi-
189        branched capturing and non-capturing groups, repeated or not, and also to
190        positive assertions (capturing in negative assertions does not happen
191        in PCRE) and also to nested atomic groups.
192    
193    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
194        subject after a captured substring, to make it easier to tell which of a
195        number of identical substrings has been captured.
196    
197    24. The way atomic groups are processed by pcre_exec() has been changed so that
198        if they are repeated, backtracking one repetition now resets captured
199        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
200        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
201        "aaa". Previously, it would have been "a". As part of this code
202        refactoring, the way recursive calls are handled has also been changed.
203    
204    25. If an assertion condition captured any substrings, they were not passed
205        back unless some other capturing happened later. For example, if
206        (?(?=(a))a) was matched against "a", no capturing was returned.
207    
208    26. When studying a pattern that contained subroutine calls or assertions,
209        the code for finding the minimum length of a possible match was handling
210        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
211        group 1 called group 2 while simultaneously a separate group 2 called group
212        1). A stack overflow occurred in this case. I have fixed this by limiting
213        the recursion depth to 10.
214    
215    27. Updated RunTest.bat in the distribution to the version supplied by Tom
216        Fortmann. This supports explicit test numbers on the command line, and has
217        argument validation and error reporting.
218    
219    28. An instance of \X with an unlimited repeat could fail if at any point the
220        first character it looked at was a mark character.
221    
222    29. Some minor code refactoring concerning Unicode properties and scripts
223        should reduce the stack requirement of match() slightly.
224    
225    30. Added the '=' option to pcretest to check the setting of unused capturing
226        slots at the end of the pattern, which are documented as being -1, but are
227        not included in the return count.
228    
229    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
230        compiled something random. Now it gives a compile-time error (as does
231        Perl).
232    
233    32. A *MARK encountered during the processing of a positive assertion is now
234        recorded and passed back (compatible with Perl).
235    
236    33. If --only-matching or --colour was set on a pcregrep call whose pattern
237        had alternative anchored branches, the search for a second match in a line
238        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
239        matched the line "0102" twice. The same bug affected patterns that started
240        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
241        twice.
242    
243    34. Previously, PCRE did not allow quantification of assertions. However, Perl
244        does, and because of capturing effects, quantifying parenthesized
245        assertions may at times be useful. Quantifiers are now allowed for
246        parenthesized assertions.
247    
248    35. A minor code tidy in pcre_compile() when checking options for \R usage.
249    
250    36. \g was being checked for fancy things in a character class, when it should
251        just be a literal "g".
252    
253    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
254        appearance of a nested POSIX class supersedes an apparent external class.
255        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
256        unescaped square brackets may also appear as part of class names. For
257        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
258        more like Perl. (But see 8.20/1 above.)
259    
260    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
261        was because it thought it was \N{name}, which is not supported).
262    
263    39. Add minix to OS list not supporting the -S option in pcretest.
264    
265    40. PCRE tries to detect cases of infinite recursion at compile time, but it
266        cannot analyze patterns in sufficient detail to catch mutual recursions
267        such as ((?1))((?2)). There is now a runtime test that gives an error if a
268        subgroup is called recursively as a subpattern for a second time at the
269        same position in the subject string. In previous releases this might have
270        been caught by the recursion limit, or it might have run out of stack.
271    
272    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
273        happen only once. PCRE was, however incorrectly giving a compile time error
274        "recursive call could loop indefinitely" because it cannot analyze the
275        pattern in sufficient detail. The compile time test no longer happens when
276        PCRE is compiling a conditional subpattern, but actual runaway loops are
277        now caught at runtime (see 40 above).
278    
279    42. It seems that Perl allows any characters other than a closing parenthesis
280        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
281        has been changed to be the same.
282    
283    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
284        as not to get warnings when autogen.sh is called. Also changed
285        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
286    
287    44. To help people who use pcregrep to scan files containing exceedingly long
288        lines, the following changes have been made:
289    
290        (a) The default value of the buffer size parameter has been increased from
291            8K to 20K. (The actual buffer used is three times this size.)
292    
293        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
294            PCRE is built.
295    
296        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
297            to be set at run time.
298    
299        (d) Numerical values in pcregrep options can be followed by K or M, for
300            example --buffer-size=50K.
301    
302        (e) If a line being scanned overflows pcregrep's buffer, an error is now
303            given and the return code is set to 2.
304    
305    45. Add a pointer to the latest mark to the callout data block.
306    
307    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
308        partial match of an empty string instead of no match. This was specific to
309        the use of ".".
310    
311    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
312        complete match instead of a partial match. This bug was dependent on both
313        the PCRE_UTF8 and PCRE_DOTALL options being set.
314    
315    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
316        starting byte set, because \b was not being ignored.
317    
318    
319  Version 8.12 15-Jan-2011  Version 8.12 15-Jan-2011
320  ------------------------  ------------------------

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