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revision 592 by ph10, Sat Apr 30 17:37:37 2011 UTC revision 740 by zherczeg, Mon Oct 31 06:10:14 2011 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.13 30-Apr-2011  Version 8.21
5    ------------
6    
7    1.  Updating the JIT compiler.
8    
9    
10    Version 8.20 21-Oct-2011
11    ------------------------
12    
13    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
14        a POSIX class. After further experiments with Perl, which convinced me that
15        Perl has bugs and confusions, a closing square bracket is no longer allowed
16        in a POSIX name. This bug also affected patterns with classes that started
17        with full stops.
18    
19    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
20        captured substring, but while checking the failing first alternative,
21        substring 1 is temporarily captured. If the output vector supplied to
22        pcre_exec() was not big enough for this capture, the yield of the function
23        was still zero ("insufficient space for captured substrings"). This cannot
24        be totally fixed without adding another stack variable, which seems a lot
25        of expense for a edge case. However, I have improved the situation in cases
26        such as /(a)(b)x|abc/ matched against "abc", where the return code
27        indicates that fewer than the maximum number of slots in the ovector have
28        been set.
29    
30    3.  Related to (2) above: when there are more back references in a pattern than
31        slots in the output vector, pcre_exec() uses temporary memory during
32        matching, and copies in the captures as far as possible afterwards. It was
33        using the entire output vector, but this conflicts with the specification
34        that only 2/3 is used for passing back captured substrings. Now it uses
35        only the first 2/3, for compatibility. This is, of course, another edge
36        case.
37    
38    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
39        main code base, and can be used by building with --enable-jit. When this is
40        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
41        runtime --no-jit option is given.
42    
43    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
44        ovector, the return from the function was zero, implying that there were
45        other matches that did not fit. The correct "exactly full" value is now
46        returned.
47    
48    6.  If a subpattern that was called recursively or as a subroutine contained
49        (*PRUNE) or any other control that caused it to give a non-standard return,
50        invalid errors such as "Error -26 (nested recursion at the same subject
51        position)" or even infinite loops could occur.
52    
53    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
54        computing the minimum length on reaching *ACCEPT, and so ended up with the
55        wrong value of 1 rather than 0. Further investigation indicates that
56        computing a minimum subject length in the presence of *ACCEPT is difficult
57        (think back references, subroutine calls), and so I have changed the code
58        so that no minimum is registered for a pattern that contains *ACCEPT.
59    
60    8.  If (*THEN) was present in the first (true) branch of a conditional group,
61        it was not handled as intended. [But see 16 below.]
62    
63    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
64        Sheri Pierce.
65    
66    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
67        the first byte in a match must be "a".
68    
69    11. Change 17 for 8.13 increased the recursion depth for patterns like
70        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
71        pattern contains any instances of (*THEN). If it does not, the old
72        optimizations are restored. It would be nice to do this on a per-group
73        basis, but at the moment that is not feasible.
74    
75    12. In some environments, the output of pcretest -C is CRLF terminated. This
76        broke RunTest's code that checks for the link size. A single white space
77        character after the value is now allowed for.
78    
79    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
80        For "fr", it uses the Windows-specific input and output files.
81    
82    14. If (*THEN) appeared in a group that was called recursively or as a
83        subroutine, it did not work as intended. [But see next item.]
84    
85    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
86        pattern fragments (but not containing any | characters). If A and B are
87        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
88        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
89        D. In other words, Perl considers parentheses that do not contain any |
90        characters to be part of a surrounding alternative, whereas PCRE was
91        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
92        differently. PCRE now behaves in the same way as Perl, except in the case
93        of subroutine/recursion calls such as (?1) which have in any case always
94        been different (but PCRE had them first :-).
95    
96    16. Related to 15 above: Perl does not treat the | in a conditional group as
97        creating alternatives. Such a group is treated in the same way as an
98        ordinary group without any | characters when processing (*THEN). PCRE has
99        been changed to match Perl's behaviour.
100    
101    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
102        RunGrepTest script failed.
103    
104    18. Change 22 for version 13 caused atomic groups to use more stack. This is
105        inevitable for groups that contain captures, but it can lead to a lot of
106        stack use in large patterns. The old behaviour has been restored for atomic
107        groups that do not contain any capturing parentheses.
108    
109    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
110        suppress the check for a minimum subject length at run time. (If it was
111        given to pcre_exec() or pcre_dfa_exec() it did work.)
112    
113    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
114        fail to work when decoding hex characters in data strings in EBCDIC
115        environments.
116    
117    21. It appears that in at least one Mac OS environment, the isxdigit() function
118        is implemented as a macro that evaluates to its argument more than once,
119        contravening the C 90 Standard (I haven't checked a later standard). There
120        was an instance in pcretest which caused it to go wrong when processing
121        \x{...} escapes in subject strings. The has been rewritten to avoid using
122        things like p++ in the argument of isxdigit().
123    
124    
125    Version 8.13 16-Aug-2011
126  ------------------------  ------------------------
127    
128  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.
129    
130    2.  Two minor typos in pcre_internal.h have been fixed.
131    
132    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
133        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
134        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
135    
136    4.  There were a number of related bugs in the code for matching backrefences
137        caselessly in UTF-8 mode when codes for the characters concerned were
138        different numbers of bytes. For example, U+023A and U+2C65 are an upper
139        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
140        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
141        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
142        2-byte code at the end of the subject (it thought there wasn't enough data
143        left).
144    
145    5.  Comprehensive information about what went wrong is now returned by
146        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
147        as the output vector has at least 2 elements. The offset of the start of
148        the failing character and a reason code are placed in the vector.
149    
150    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
151        now returned is for the first byte of the failing character, instead of the
152        last byte inspected. This is an incompatible change, but I hope it is small
153        enough not to be a problem. It makes the returned offset consistent with
154        pcre_exec() and pcre_dfa_exec().
155    
156    7.  pcretest now gives a text phrase as well as the error number when
157        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
158        failure, the offset and reason code are output.
159    
160    8.  When \R was used with a maximizing quantifier it failed to skip backwards
161        over a \r\n pair if the subsequent match failed. Instead, it just skipped
162        back over a single character (\n). This seems wrong (because it treated the
163        two characters as a single entity when going forwards), conflicts with the
164        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
165        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
166        has been changed.
167    
168    9.  Some internal refactoring has changed the processing so that the handling
169        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
170        time (the PCRE_DOTALL option was changed this way some time ago: version
171        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
172        which was always a bit of a fudge. It also means that there is one less
173        argument for the match() function, which reduces its stack requirements
174        slightly. This change also fixes an incompatibility with Perl: the pattern
175        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
176    
177    10. More internal refactoring has drastically reduced the number of recursive
178        calls to match() for possessively repeated groups such as (abc)++ when
179        using pcre_exec().
180    
181    11. While implementing 10, a number of bugs in the handling of groups were
182        discovered and fixed:
183    
184        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
185        (a|)*(?1) gave a compile-time internal error.
186        ((a|)+)+  did not notice that the outer group could match an empty string.
187        (^a|^)+   was not marked as anchored.
188        (.*a|.*)+ was not marked as matching at start or after a newline.
189    
190    12. Yet more internal refactoring has removed another argument from the match()
191        function. Special calls to this function are now indicated by setting a
192        value in a variable in the "match data" data block.
193    
194    13. Be more explicit in pcre_study() instead of relying on "default" for
195        opcodes that mean there is no starting character; this means that when new
196        ones are added and accidentally left out of pcre_study(), testing should
197        pick them up.
198    
199    14. The -s option of pcretest has been documented for ages as being an old
200        synonym of -m (show memory usage). I have changed it to mean "force study
201        for every regex", that is, assume /S for every regex. This is similar to -i
202        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
203        using it. It makes it easier to run collections of tests with and without
204        study enabled, and thereby test pcre_study() more easily. All the standard
205        tests are now run with and without -s (but some patterns can be marked as
206        "never study" - see 20 below).
207    
208    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
209        restoration of the capturing data to the outer values was not happening
210        correctly.
211    
212    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
213        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
214        pattern had matched an empty string, and so incorrectly returned a no
215        match.
216    
217    17. There was optimizing code for the last branch of non-capturing parentheses,
218        and also for the obeyed branch of a conditional subexpression, which used
219        tail recursion to cut down on stack usage. Unfortunately, now that there is
220        the possibility of (*THEN) occurring in these branches, tail recursion is
221        no longer possible because the return has to be checked for (*THEN). These
222        two optimizations have therefore been removed. [But see 8.20/11 above.]
223    
224    18. If a pattern containing \R was studied, it was assumed that \R always
225        matched two bytes, thus causing the minimum subject length to be
226        incorrectly computed because \R can also match just one byte.
227    
228    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
229        was incorrectly computed.
230    
231    20. If /S is present twice on a test pattern in pcretest input, it now
232        *disables* studying, thereby overriding the use of -s on the command line
233        (see 14 above). This is necessary for one or two tests to keep the output
234        identical in both cases.
235    
236    21. When (*ACCEPT) was used in an assertion that matched an empty string and
237        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
238    
239    22. When an atomic group that contained a capturing parenthesis was
240        successfully matched, but the branch in which it appeared failed, the
241        capturing was not being forgotten if a higher numbered group was later
242        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
243        group 1 to "a", when in fact it should be unset. This applied to multi-
244        branched capturing and non-capturing groups, repeated or not, and also to
245        positive assertions (capturing in negative assertions does not happen
246        in PCRE) and also to nested atomic groups.
247    
248    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
249        subject after a captured substring, to make it easier to tell which of a
250        number of identical substrings has been captured.
251    
252    24. The way atomic groups are processed by pcre_exec() has been changed so that
253        if they are repeated, backtracking one repetition now resets captured
254        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
255        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
256        "aaa". Previously, it would have been "a". As part of this code
257        refactoring, the way recursive calls are handled has also been changed.
258    
259    25. If an assertion condition captured any substrings, they were not passed
260        back unless some other capturing happened later. For example, if
261        (?(?=(a))a) was matched against "a", no capturing was returned.
262    
263    26. When studying a pattern that contained subroutine calls or assertions,
264        the code for finding the minimum length of a possible match was handling
265        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
266        group 1 called group 2 while simultaneously a separate group 2 called group
267        1). A stack overflow occurred in this case. I have fixed this by limiting
268        the recursion depth to 10.
269    
270    27. Updated RunTest.bat in the distribution to the version supplied by Tom
271        Fortmann. This supports explicit test numbers on the command line, and has
272        argument validation and error reporting.
273    
274    28. An instance of \X with an unlimited repeat could fail if at any point the
275        first character it looked at was a mark character.
276    
277    29. Some minor code refactoring concerning Unicode properties and scripts
278        should reduce the stack requirement of match() slightly.
279    
280    30. Added the '=' option to pcretest to check the setting of unused capturing
281        slots at the end of the pattern, which are documented as being -1, but are
282        not included in the return count.
283    
284    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
285        compiled something random. Now it gives a compile-time error (as does
286        Perl).
287    
288    32. A *MARK encountered during the processing of a positive assertion is now
289        recorded and passed back (compatible with Perl).
290    
291    33. If --only-matching or --colour was set on a pcregrep call whose pattern
292        had alternative anchored branches, the search for a second match in a line
293        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
294        matched the line "0102" twice. The same bug affected patterns that started
295        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
296        twice.
297    
298    34. Previously, PCRE did not allow quantification of assertions. However, Perl
299        does, and because of capturing effects, quantifying parenthesized
300        assertions may at times be useful. Quantifiers are now allowed for
301        parenthesized assertions.
302    
303    35. A minor code tidy in pcre_compile() when checking options for \R usage.
304    
305    36. \g was being checked for fancy things in a character class, when it should
306        just be a literal "g".
307    
308    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
309        appearance of a nested POSIX class supersedes an apparent external class.
310        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
311        unescaped square brackets may also appear as part of class names. For
312        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
313        more like Perl. (But see 8.20/1 above.)
314    
315    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
316        was because it thought it was \N{name}, which is not supported).
317    
318    39. Add minix to OS list not supporting the -S option in pcretest.
319    
320    40. PCRE tries to detect cases of infinite recursion at compile time, but it
321        cannot analyze patterns in sufficient detail to catch mutual recursions
322        such as ((?1))((?2)). There is now a runtime test that gives an error if a
323        subgroup is called recursively as a subpattern for a second time at the
324        same position in the subject string. In previous releases this might have
325        been caught by the recursion limit, or it might have run out of stack.
326    
327    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
328        happen only once. PCRE was, however incorrectly giving a compile time error
329        "recursive call could loop indefinitely" because it cannot analyze the
330        pattern in sufficient detail. The compile time test no longer happens when
331        PCRE is compiling a conditional subpattern, but actual runaway loops are
332        now caught at runtime (see 40 above).
333    
334    42. It seems that Perl allows any characters other than a closing parenthesis
335        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
336        has been changed to be the same.
337    
338    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
339        as not to get warnings when autogen.sh is called. Also changed
340        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
341    
342    44. To help people who use pcregrep to scan files containing exceedingly long
343        lines, the following changes have been made:
344    
345        (a) The default value of the buffer size parameter has been increased from
346            8K to 20K. (The actual buffer used is three times this size.)
347    
348        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
349            PCRE is built.
350    
351        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
352            to be set at run time.
353    
354        (d) Numerical values in pcregrep options can be followed by K or M, for
355            example --buffer-size=50K.
356    
357        (e) If a line being scanned overflows pcregrep's buffer, an error is now
358            given and the return code is set to 2.
359    
360    45. Add a pointer to the latest mark to the callout data block.
361    
362    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
363        partial match of an empty string instead of no match. This was specific to
364        the use of ".".
365    
366    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
367        complete match instead of a partial match. This bug was dependent on both
368        the PCRE_UTF8 and PCRE_DOTALL options being set.
369    
370    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
371        starting byte set, because \b was not being ignored.
372    
373    
374  Version 8.12 15-Jan-2011  Version 8.12 15-Jan-2011
375  ------------------------  ------------------------

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