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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    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    7. If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
46       computing the minimum length on reaching *ACCEPT, and so ended up with the
47       wrong value of 1 rather than 0. Further investigation indicates that
48       computing a minimum subject length in the presence of *ACCEPT is difficult
49       (think back references, subroutine calls), and so I have changed the code so
50       that no minimum is registered for a pattern that contains *ACCEPT.
51    
52    8. If (*THEN) was present in the first (true) branch of a conditional group,
53       it was not handled as intended.
54    
55    
56    Version 8.13 16-Aug-2011
57    ------------------------
58    
59    1.  The Unicode data tables have been updated to Unicode 6.0.0.
60    
61    2.  Two minor typos in pcre_internal.h have been fixed.
62    
63    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
64        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
65        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
66    
67    4.  There were a number of related bugs in the code for matching backrefences
68        caselessly in UTF-8 mode when codes for the characters concerned were
69        different numbers of bytes. For example, U+023A and U+2C65 are an upper
70        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
71        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
72        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
73        2-byte code at the end of the subject (it thought there wasn't enough data
74        left).
75    
76    5.  Comprehensive information about what went wrong is now returned by
77        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
78        as the output vector has at least 2 elements. The offset of the start of
79        the failing character and a reason code are placed in the vector.
80    
81    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
82        now returned is for the first byte of the failing character, instead of the
83        last byte inspected. This is an incompatible change, but I hope it is small
84        enough not to be a problem. It makes the returned offset consistent with
85        pcre_exec() and pcre_dfa_exec().
86    
87    7.  pcretest now gives a text phrase as well as the error number when
88        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
89        failure, the offset and reason code are output.
90    
91    8.  When \R was used with a maximizing quantifier it failed to skip backwards
92        over a \r\n pair if the subsequent match failed. Instead, it just skipped
93        back over a single character (\n). This seems wrong (because it treated the
94        two characters as a single entity when going forwards), conflicts with the
95        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
96        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
97        has been changed.
98    
99    9.  Some internal refactoring has changed the processing so that the handling
100        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
101        time (the PCRE_DOTALL option was changed this way some time ago: version
102        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
103        which was always a bit of a fudge. It also means that there is one less
104        argument for the match() function, which reduces its stack requirements
105        slightly. This change also fixes an incompatibility with Perl: the pattern
106        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
107    
108    10. More internal refactoring has drastically reduced the number of recursive
109        calls to match() for possessively repeated groups such as (abc)++ when
110        using pcre_exec().
111    
112    11. While implementing 10, a number of bugs in the handling of groups were
113        discovered and fixed:
114    
115        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
116        (a|)*(?1) gave a compile-time internal error.
117        ((a|)+)+  did not notice that the outer group could match an empty string.
118        (^a|^)+   was not marked as anchored.
119        (.*a|.*)+ was not marked as matching at start or after a newline.
120    
121    12. Yet more internal refactoring has removed another argument from the match()
122        function. Special calls to this function are now indicated by setting a
123        value in a variable in the "match data" data block.
124    
125    13. Be more explicit in pcre_study() instead of relying on "default" for
126        opcodes that mean there is no starting character; this means that when new
127        ones are added and accidentally left out of pcre_study(), testing should
128        pick them up.
129    
130    14. The -s option of pcretest has been documented for ages as being an old
131        synonym of -m (show memory usage). I have changed it to mean "force study
132        for every regex", that is, assume /S for every regex. This is similar to -i
133        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
134        using it. It makes it easier to run collections of tests with and without
135        study enabled, and thereby test pcre_study() more easily. All the standard
136        tests are now run with and without -s (but some patterns can be marked as
137        "never study" - see 20 below).
138    
139    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
140        restoration of the capturing data to the outer values was not happening
141        correctly.
142    
143    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
144        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
145        pattern had matched an empty string, and so incorrectly returned a no
146        match.
147    
148    17. There was optimizing code for the last branch of non-capturing parentheses,
149        and also for the obeyed branch of a conditional subexpression, which used
150        tail recursion to cut down on stack usage. Unfortunately, now that there is
151        the possibility of (*THEN) occurring in these branches, tail recursion is
152        no longer possible because the return has to be checked for (*THEN). These
153        two optimizations have therefore been removed.
154    
155    18. If a pattern containing \R was studied, it was assumed that \R always
156        matched two bytes, thus causing the minimum subject length to be
157        incorrectly computed because \R can also match just one byte.
158    
159    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
160        was incorrectly computed.
161    
162    20. If /S is present twice on a test pattern in pcretest input, it now
163        *disables* studying, thereby overriding the use of -s on the command line
164        (see 14 above). This is necessary for one or two tests to keep the output
165        identical in both cases.
166    
167    21. When (*ACCEPT) was used in an assertion that matched an empty string and
168        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
169    
170    22. When an atomic group that contained a capturing parenthesis was
171        successfully matched, but the branch in which it appeared failed, the
172        capturing was not being forgotten if a higher numbered group was later
173        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
174        group 1 to "a", when in fact it should be unset. This applied to multi-
175        branched capturing and non-capturing groups, repeated or not, and also to
176        positive assertions (capturing in negative assertions does not happen
177        in PCRE) and also to nested atomic groups.
178    
179    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
180        subject after a captured substring, to make it easier to tell which of a
181        number of identical substrings has been captured.
182    
183    24. The way atomic groups are processed by pcre_exec() has been changed so that
184        if they are repeated, backtracking one repetition now resets captured
185        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
186        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
187        "aaa". Previously, it would have been "a". As part of this code
188        refactoring, the way recursive calls are handled has also been changed.
189    
190    25. If an assertion condition captured any substrings, they were not passed
191        back unless some other capturing happened later. For example, if
192        (?(?=(a))a) was matched against "a", no capturing was returned.
193    
194    26. When studying a pattern that contained subroutine calls or assertions,
195        the code for finding the minimum length of a possible match was handling
196        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
197        group 1 called group 2 while simultaneously a separate group 2 called group
198        1). A stack overflow occurred in this case. I have fixed this by limiting
199        the recursion depth to 10.
200    
201    27. Updated RunTest.bat in the distribution to the version supplied by Tom
202        Fortmann. This supports explicit test numbers on the command line, and has
203        argument validation and error reporting.
204    
205    28. An instance of \X with an unlimited repeat could fail if at any point the
206        first character it looked at was a mark character.
207    
208    29. Some minor code refactoring concerning Unicode properties and scripts
209        should reduce the stack requirement of match() slightly.
210    
211    30. Added the '=' option to pcretest to check the setting of unused capturing
212        slots at the end of the pattern, which are documented as being -1, but are
213        not included in the return count.
214    
215    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
216        compiled something random. Now it gives a compile-time error (as does
217        Perl).
218    
219    32. A *MARK encountered during the processing of a positive assertion is now
220        recorded and passed back (compatible with Perl).
221    
222    33. If --only-matching or --colour was set on a pcregrep call whose pattern
223        had alternative anchored branches, the search for a second match in a line
224        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
225        matched the line "0102" twice. The same bug affected patterns that started
226        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
227        twice.
228    
229    34. Previously, PCRE did not allow quantification of assertions. However, Perl
230        does, and because of capturing effects, quantifying parenthesized
231        assertions may at times be useful. Quantifiers are now allowed for
232        parenthesized assertions.
233    
234    35. A minor code tidy in pcre_compile() when checking options for \R usage.
235    
236    36. \g was being checked for fancy things in a character class, when it should
237        just be a literal "g".
238    
239    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
240        appearance of a nested POSIX class supersedes an apparent external class.
241        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
242        unescaped square brackets may also appear as part of class names. For
243        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
244        more like Perl. (But see 8.20/1 above.)
245    
246    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
247        was because it thought it was \N{name}, which is not supported).
248    
249    39. Add minix to OS list not supporting the -S option in pcretest.
250    
251    40. PCRE tries to detect cases of infinite recursion at compile time, but it
252        cannot analyze patterns in sufficient detail to catch mutual recursions
253        such as ((?1))((?2)). There is now a runtime test that gives an error if a
254        subgroup is called recursively as a subpattern for a second time at the
255        same position in the subject string. In previous releases this might have
256        been caught by the recursion limit, or it might have run out of stack.
257    
258    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
259        happen only once. PCRE was, however incorrectly giving a compile time error
260        "recursive call could loop indefinitely" because it cannot analyze the
261        pattern in sufficient detail. The compile time test no longer happens when
262        PCRE is compiling a conditional subpattern, but actual runaway loops are
263        now caught at runtime (see 40 above).
264    
265    42. It seems that Perl allows any characters other than a closing parenthesis
266        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
267        has been changed to be the same.
268    
269    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
270        as not to get warnings when autogen.sh is called. Also changed
271        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
272    
273    44. To help people who use pcregrep to scan files containing exceedingly long
274        lines, the following changes have been made:
275    
276        (a) The default value of the buffer size parameter has been increased from
277            8K to 20K. (The actual buffer used is three times this size.)
278    
279        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
280            PCRE is built.
281    
282        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
283            to be set at run time.
284    
285        (d) Numerical values in pcregrep options can be followed by K or M, for
286            example --buffer-size=50K.
287    
288        (e) If a line being scanned overflows pcregrep's buffer, an error is now
289            given and the return code is set to 2.
290    
291    45. Add a pointer to the latest mark to the callout data block.
292    
293    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
294        partial match of an empty string instead of no match. This was specific to
295        the use of ".".
296    
297    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
298        complete match instead of a partial match. This bug was dependent on both
299        the PCRE_UTF8 and PCRE_DOTALL options being set.
300    
301    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
302        starting byte set, because \b was not being ignored.
303    
304    
305    Version 8.12 15-Jan-2011
306    ------------------------
307    
308    1.  Fixed some typos in the markup of the man pages, and wrote a script that
309        checks for such things as part of the documentation building process.
310    
311    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
312        --match-limit and --recursion-limit options (added for 8.11). In
313        particular, this made one of the standard tests fail. (The integer value
314        went into the wrong half of a long int.)
315    
316    3.  If the --colour option was given to pcregrep with -v (invert match), it
317        did strange things, either producing crazy output, or crashing. It should,
318        of course, ignore a request for colour when reporting lines that do not
319        match.
320    
321    4.  Another pcregrep bug caused similar problems if --colour was specified with
322        -M (multiline) and the pattern match finished with a line ending.
323    
324    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
325        matched in multiline mode, the following line was shown as part of the
326        match. This seems wrong, so I have changed it.
327    
328    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
329        the check for further matches in the same line (so they could be coloured)
330        to overrun the end of the current line. If another match was found, it was
331        incorrectly shown (and then shown again when found in the next line).
332    
333    7.  If pcregrep was compiled under Windows, there was a reference to the
334        function pcregrep_exit() before it was defined. I am assuming this was
335        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
336        reported by a user. I've moved the definition above the reference.
337    
338    
339  Version 8.11 10-Dec-2010  Version 8.11 10-Dec-2010
340  ------------------------  ------------------------
341    

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