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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.15 12-Jan-2011  Version 8.20 23-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    12. In some environments, the output of pcretest -C is CRLF terminated. This
70        broke RunTest's code that checks for the link size. A single white space
71        after the value is now allowed for.
72    
73    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
74        For "fr", it uses the Windows-specific input and output files.
75    
76    14. If (*THEN) appeared in a group that was called recursively or as a
77        subroutine, it did not work as intended.
78    
79    
80    Version 8.13 16-Aug-2011
81    ------------------------
82    
83    1.  The Unicode data tables have been updated to Unicode 6.0.0.
84    
85    2.  Two minor typos in pcre_internal.h have been fixed.
86    
87    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
88        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
89        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
90    
91    4.  There were a number of related bugs in the code for matching backrefences
92        caselessly in UTF-8 mode when codes for the characters concerned were
93        different numbers of bytes. For example, U+023A and U+2C65 are an upper
94        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
95        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
96        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
97        2-byte code at the end of the subject (it thought there wasn't enough data
98        left).
99    
100    5.  Comprehensive information about what went wrong is now returned by
101        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
102        as the output vector has at least 2 elements. The offset of the start of
103        the failing character and a reason code are placed in the vector.
104    
105    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
106        now returned is for the first byte of the failing character, instead of the
107        last byte inspected. This is an incompatible change, but I hope it is small
108        enough not to be a problem. It makes the returned offset consistent with
109        pcre_exec() and pcre_dfa_exec().
110    
111    7.  pcretest now gives a text phrase as well as the error number when
112        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
113        failure, the offset and reason code are output.
114    
115    8.  When \R was used with a maximizing quantifier it failed to skip backwards
116        over a \r\n pair if the subsequent match failed. Instead, it just skipped
117        back over a single character (\n). This seems wrong (because it treated the
118        two characters as a single entity when going forwards), conflicts with the
119        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
120        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
121        has been changed.
122    
123    9.  Some internal refactoring has changed the processing so that the handling
124        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
125        time (the PCRE_DOTALL option was changed this way some time ago: version
126        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
127        which was always a bit of a fudge. It also means that there is one less
128        argument for the match() function, which reduces its stack requirements
129        slightly. This change also fixes an incompatibility with Perl: the pattern
130        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
131    
132    10. More internal refactoring has drastically reduced the number of recursive
133        calls to match() for possessively repeated groups such as (abc)++ when
134        using pcre_exec().
135    
136    11. While implementing 10, a number of bugs in the handling of groups were
137        discovered and fixed:
138    
139        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
140        (a|)*(?1) gave a compile-time internal error.
141        ((a|)+)+  did not notice that the outer group could match an empty string.
142        (^a|^)+   was not marked as anchored.
143        (.*a|.*)+ was not marked as matching at start or after a newline.
144    
145    12. Yet more internal refactoring has removed another argument from the match()
146        function. Special calls to this function are now indicated by setting a
147        value in a variable in the "match data" data block.
148    
149    13. Be more explicit in pcre_study() instead of relying on "default" for
150        opcodes that mean there is no starting character; this means that when new
151        ones are added and accidentally left out of pcre_study(), testing should
152        pick them up.
153    
154    14. The -s option of pcretest has been documented for ages as being an old
155        synonym of -m (show memory usage). I have changed it to mean "force study
156        for every regex", that is, assume /S for every regex. This is similar to -i
157        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
158        using it. It makes it easier to run collections of tests with and without
159        study enabled, and thereby test pcre_study() more easily. All the standard
160        tests are now run with and without -s (but some patterns can be marked as
161        "never study" - see 20 below).
162    
163    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
164        restoration of the capturing data to the outer values was not happening
165        correctly.
166    
167    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
168        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
169        pattern had matched an empty string, and so incorrectly returned a no
170        match.
171    
172    17. There was optimizing code for the last branch of non-capturing parentheses,
173        and also for the obeyed branch of a conditional subexpression, which used
174        tail recursion to cut down on stack usage. Unfortunately, now that there is
175        the possibility of (*THEN) occurring in these branches, tail recursion is
176        no longer possible because the return has to be checked for (*THEN). These
177        two optimizations have therefore been removed. [But see 8.20/11 above.]
178    
179    18. If a pattern containing \R was studied, it was assumed that \R always
180        matched two bytes, thus causing the minimum subject length to be
181        incorrectly computed because \R can also match just one byte.
182    
183    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
184        was incorrectly computed.
185    
186    20. If /S is present twice on a test pattern in pcretest input, it now
187        *disables* studying, thereby overriding the use of -s on the command line
188        (see 14 above). This is necessary for one or two tests to keep the output
189        identical in both cases.
190    
191    21. When (*ACCEPT) was used in an assertion that matched an empty string and
192        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
193    
194    22. When an atomic group that contained a capturing parenthesis was
195        successfully matched, but the branch in which it appeared failed, the
196        capturing was not being forgotten if a higher numbered group was later
197        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
198        group 1 to "a", when in fact it should be unset. This applied to multi-
199        branched capturing and non-capturing groups, repeated or not, and also to
200        positive assertions (capturing in negative assertions does not happen
201        in PCRE) and also to nested atomic groups.
202    
203    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
204        subject after a captured substring, to make it easier to tell which of a
205        number of identical substrings has been captured.
206    
207    24. The way atomic groups are processed by pcre_exec() has been changed so that
208        if they are repeated, backtracking one repetition now resets captured
209        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
210        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
211        "aaa". Previously, it would have been "a". As part of this code
212        refactoring, the way recursive calls are handled has also been changed.
213    
214    25. If an assertion condition captured any substrings, they were not passed
215        back unless some other capturing happened later. For example, if
216        (?(?=(a))a) was matched against "a", no capturing was returned.
217    
218    26. When studying a pattern that contained subroutine calls or assertions,
219        the code for finding the minimum length of a possible match was handling
220        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
221        group 1 called group 2 while simultaneously a separate group 2 called group
222        1). A stack overflow occurred in this case. I have fixed this by limiting
223        the recursion depth to 10.
224    
225    27. Updated RunTest.bat in the distribution to the version supplied by Tom
226        Fortmann. This supports explicit test numbers on the command line, and has
227        argument validation and error reporting.
228    
229    28. An instance of \X with an unlimited repeat could fail if at any point the
230        first character it looked at was a mark character.
231    
232    29. Some minor code refactoring concerning Unicode properties and scripts
233        should reduce the stack requirement of match() slightly.
234    
235    30. Added the '=' option to pcretest to check the setting of unused capturing
236        slots at the end of the pattern, which are documented as being -1, but are
237        not included in the return count.
238    
239    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
240        compiled something random. Now it gives a compile-time error (as does
241        Perl).
242    
243    32. A *MARK encountered during the processing of a positive assertion is now
244        recorded and passed back (compatible with Perl).
245    
246    33. If --only-matching or --colour was set on a pcregrep call whose pattern
247        had alternative anchored branches, the search for a second match in a line
248        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
249        matched the line "0102" twice. The same bug affected patterns that started
250        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
251        twice.
252    
253    34. Previously, PCRE did not allow quantification of assertions. However, Perl
254        does, and because of capturing effects, quantifying parenthesized
255        assertions may at times be useful. Quantifiers are now allowed for
256        parenthesized assertions.
257    
258    35. A minor code tidy in pcre_compile() when checking options for \R usage.
259    
260    36. \g was being checked for fancy things in a character class, when it should
261        just be a literal "g".
262    
263    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
264        appearance of a nested POSIX class supersedes an apparent external class.
265        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
266        unescaped square brackets may also appear as part of class names. For
267        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
268        more like Perl. (But see 8.20/1 above.)
269    
270    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
271        was because it thought it was \N{name}, which is not supported).
272    
273    39. Add minix to OS list not supporting the -S option in pcretest.
274    
275    40. PCRE tries to detect cases of infinite recursion at compile time, but it
276        cannot analyze patterns in sufficient detail to catch mutual recursions
277        such as ((?1))((?2)). There is now a runtime test that gives an error if a
278        subgroup is called recursively as a subpattern for a second time at the
279        same position in the subject string. In previous releases this might have
280        been caught by the recursion limit, or it might have run out of stack.
281    
282    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
283        happen only once. PCRE was, however incorrectly giving a compile time error
284        "recursive call could loop indefinitely" because it cannot analyze the
285        pattern in sufficient detail. The compile time test no longer happens when
286        PCRE is compiling a conditional subpattern, but actual runaway loops are
287        now caught at runtime (see 40 above).
288    
289    42. It seems that Perl allows any characters other than a closing parenthesis
290        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
291        has been changed to be the same.
292    
293    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
294        as not to get warnings when autogen.sh is called. Also changed
295        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
296    
297    44. To help people who use pcregrep to scan files containing exceedingly long
298        lines, the following changes have been made:
299    
300        (a) The default value of the buffer size parameter has been increased from
301            8K to 20K. (The actual buffer used is three times this size.)
302    
303        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
304            PCRE is built.
305    
306        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
307            to be set at run time.
308    
309        (d) Numerical values in pcregrep options can be followed by K or M, for
310            example --buffer-size=50K.
311    
312        (e) If a line being scanned overflows pcregrep's buffer, an error is now
313            given and the return code is set to 2.
314    
315    45. Add a pointer to the latest mark to the callout data block.
316    
317    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
318        partial match of an empty string instead of no match. This was specific to
319        the use of ".".
320    
321    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
322        complete match instead of a partial match. This bug was dependent on both
323        the PCRE_UTF8 and PCRE_DOTALL options being set.
324    
325    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
326        starting byte set, because \b was not being ignored.
327    
328    
329    Version 8.12 15-Jan-2011
330  ------------------------  ------------------------
331    
332  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

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