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revision 604 by ph10, Thu Jun 2 19:04:54 2011 UTC revision 701 by ph10, Tue Sep 20 11:30:56 2011 UTC
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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    
64    Version 8.13 16-Aug-2011
65  ------------------------  ------------------------
66    
67  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.
# Line 20  Version 8.13 30-Apr-2011 Line 80  Version 8.13 30-Apr-2011
80      code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a      code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
81      2-byte code at the end of the subject (it thought there wasn't enough data      2-byte code at the end of the subject (it thought there wasn't enough data
82      left).      left).
83    
84  5.  Comprehensive information about what went wrong is now returned by  5.  Comprehensive information about what went wrong is now returned by
85      pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long      pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
86      as the output vector has at least 2 elements. The offset of the start of      as the output vector has at least 2 elements. The offset of the start of
87      the failing character and a reason code are placed in the vector.      the failing character and a reason code are placed in the vector.
88    
89  6.  When the UTF-8 string check fails for pcre_compile(), the offset that is  6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
90      now returned is for the first byte of the failing character, instead of the      now returned is for the first byte of the failing character, instead of the
91      last byte inspected. This is an incompatible change, but I hope it is small      last byte inspected. This is an incompatible change, but I hope it is small
92      enough not to be a problem. It makes the returned offset consistent with      enough not to be a problem. It makes the returned offset consistent with
93      pcre_exec() and pcre_dfa_exec().      pcre_exec() and pcre_dfa_exec().
94    
95  7.  pcretest now gives a text phrase as well as the error number when  7.  pcretest now gives a text phrase as well as the error number when
96      pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check      pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
97      failure, the offset and reason code are output.      failure, the offset and reason code are output.
98    
99  8.  When \R was used with a maximizing quantifier it failed to skip backwards  8.  When \R was used with a maximizing quantifier it failed to skip backwards
100      over a \r\n pair if the subsequent match failed. Instead, it just skipped      over a \r\n pair if the subsequent match failed. Instead, it just skipped
101      back over a single character (\n). This seems wrong (because it treated the      back over a single character (\n). This seems wrong (because it treated the
102      two characters as a single entity when going forwards), conflicts with the      two characters as a single entity when going forwards), conflicts with the
103      documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the      documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
104      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
105      has been changed.      has been changed.
106    
107  9.  Some internal refactoring has changed the processing so that the handling  9.  Some internal refactoring has changed the processing so that the handling
108      of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile      of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
109      time (the PCRE_DOTALL option was changed this way some time ago: version      time (the PCRE_DOTALL option was changed this way some time ago: version
110      7.7 change 16). This has made it possible to abolish the OP_OPT op code,      7.7 change 16). This has made it possible to abolish the OP_OPT op code,
111      which was always a bit of a fudge. It also means that there is one less      which was always a bit of a fudge. It also means that there is one less
112      argument for the match() function, which reduces its stack requirements      argument for the match() function, which reduces its stack requirements
113      slightly. This change also fixes an incompatibility with Perl: the pattern      slightly. This change also fixes an incompatibility with Perl: the pattern
114      (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.      (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
115    
116  10. More internal refactoring has drastically reduced the number of recursive  10. More internal refactoring has drastically reduced the number of recursive
117      calls to match() for possessively repeated groups such as (abc)++ when      calls to match() for possessively repeated groups such as (abc)++ when
118      using pcre_exec().      using pcre_exec().
119    
120  11. While implementing 10, a number of bugs in the handling of groups were  11. While implementing 10, a number of bugs in the handling of groups were
121      discovered and fixed:      discovered and fixed:
122    
123      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
124      (a|)*(?1) gave a compile-time internal error.      (a|)*(?1) gave a compile-time internal error.
125      ((a|)+)+  did not notice that the outer group could match an empty string.      ((a|)+)+  did not notice that the outer group could match an empty string.
126      (^a|^)+   was not marked as anchored.      (^a|^)+   was not marked as anchored.
127      (.*a|.*)+ was not marked as matching at start or after a newline.      (.*a|.*)+ was not marked as matching at start or after a newline.
128    
129  12. Yet more internal refactoring has removed another argument from the match()  12. Yet more internal refactoring has removed another argument from the match()
130      function. Special calls to this function are now indicated by setting a      function. Special calls to this function are now indicated by setting a
131      value in a variable in the "match data" data block.      value in a variable in the "match data" data block.
132    
133    13. Be more explicit in pcre_study() instead of relying on "default" for
134        opcodes that mean there is no starting character; this means that when new
135        ones are added and accidentally left out of pcre_study(), testing should
136        pick them up.
137    
138    14. The -s option of pcretest has been documented for ages as being an old
139        synonym of -m (show memory usage). I have changed it to mean "force study
140        for every regex", that is, assume /S for every regex. This is similar to -i
141        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
142        using it. It makes it easier to run collections of tests with and without
143        study enabled, and thereby test pcre_study() more easily. All the standard
144        tests are now run with and without -s (but some patterns can be marked as
145        "never study" - see 20 below).
146    
147    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
148        restoration of the capturing data to the outer values was not happening
149        correctly.
150    
151    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
152        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
153        pattern had matched an empty string, and so incorrectly returned a no
154        match.
155    
156    17. There was optimizing code for the last branch of non-capturing parentheses,
157        and also for the obeyed branch of a conditional subexpression, which used
158        tail recursion to cut down on stack usage. Unfortunately, now that there is
159        the possibility of (*THEN) occurring in these branches, tail recursion is
160        no longer possible because the return has to be checked for (*THEN). These
161        two optimizations have therefore been removed.
162    
163    18. If a pattern containing \R was studied, it was assumed that \R always
164        matched two bytes, thus causing the minimum subject length to be
165        incorrectly computed because \R can also match just one byte.
166    
167    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
168        was incorrectly computed.
169    
170    20. If /S is present twice on a test pattern in pcretest input, it now
171        *disables* studying, thereby overriding the use of -s on the command line
172        (see 14 above). This is necessary for one or two tests to keep the output
173        identical in both cases.
174    
175    21. When (*ACCEPT) was used in an assertion that matched an empty string and
176        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
177    
178    22. When an atomic group that contained a capturing parenthesis was
179        successfully matched, but the branch in which it appeared failed, the
180        capturing was not being forgotten if a higher numbered group was later
181        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
182        group 1 to "a", when in fact it should be unset. This applied to multi-
183        branched capturing and non-capturing groups, repeated or not, and also to
184        positive assertions (capturing in negative assertions does not happen
185        in PCRE) and also to nested atomic groups.
186    
187    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
188        subject after a captured substring, to make it easier to tell which of a
189        number of identical substrings has been captured.
190    
191    24. The way atomic groups are processed by pcre_exec() has been changed so that
192        if they are repeated, backtracking one repetition now resets captured
193        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
194        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
195        "aaa". Previously, it would have been "a". As part of this code
196        refactoring, the way recursive calls are handled has also been changed.
197    
198    25. If an assertion condition captured any substrings, they were not passed
199        back unless some other capturing happened later. For example, if
200        (?(?=(a))a) was matched against "a", no capturing was returned.
201    
202    26. When studying a pattern that contained subroutine calls or assertions,
203        the code for finding the minimum length of a possible match was handling
204        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
205        group 1 called group 2 while simultaneously a separate group 2 called group
206        1). A stack overflow occurred in this case. I have fixed this by limiting
207        the recursion depth to 10.
208    
209    27. Updated RunTest.bat in the distribution to the version supplied by Tom
210        Fortmann. This supports explicit test numbers on the command line, and has
211        argument validation and error reporting.
212    
213    28. An instance of \X with an unlimited repeat could fail if at any point the
214        first character it looked at was a mark character.
215    
216    29. Some minor code refactoring concerning Unicode properties and scripts
217        should reduce the stack requirement of match() slightly.
218    
219    30. Added the '=' option to pcretest to check the setting of unused capturing
220        slots at the end of the pattern, which are documented as being -1, but are
221        not included in the return count.
222    
223    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
224        compiled something random. Now it gives a compile-time error (as does
225        Perl).
226    
227    32. A *MARK encountered during the processing of a positive assertion is now
228        recorded and passed back (compatible with Perl).
229    
230    33. If --only-matching or --colour was set on a pcregrep call whose pattern
231        had alternative anchored branches, the search for a second match in a line
232        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
233        matched the line "0102" twice. The same bug affected patterns that started
234        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
235        twice.
236    
237    34. Previously, PCRE did not allow quantification of assertions. However, Perl
238        does, and because of capturing effects, quantifying parenthesized
239        assertions may at times be useful. Quantifiers are now allowed for
240        parenthesized assertions.
241    
242    35. A minor code tidy in pcre_compile() when checking options for \R usage.
243    
244    36. \g was being checked for fancy things in a character class, when it should
245        just be a literal "g".
246    
247    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
248        appearance of a nested POSIX class supersedes an apparent external class.
249        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
250        unescaped square brackets may also appear as part of class names. For
251        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
252        more like Perl. (But see 8.20/1 above.)
253    
254    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
255        was because it thought it was \N{name}, which is not supported).
256    
257    39. Add minix to OS list not supporting the -S option in pcretest.
258    
259    40. PCRE tries to detect cases of infinite recursion at compile time, but it
260        cannot analyze patterns in sufficient detail to catch mutual recursions
261        such as ((?1))((?2)). There is now a runtime test that gives an error if a
262        subgroup is called recursively as a subpattern for a second time at the
263        same position in the subject string. In previous releases this might have
264        been caught by the recursion limit, or it might have run out of stack.
265    
266    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
267        happen only once. PCRE was, however incorrectly giving a compile time error
268        "recursive call could loop indefinitely" because it cannot analyze the
269        pattern in sufficient detail. The compile time test no longer happens when
270        PCRE is compiling a conditional subpattern, but actual runaway loops are
271        now caught at runtime (see 40 above).
272    
273    42. It seems that Perl allows any characters other than a closing parenthesis
274        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
275        has been changed to be the same.
276    
277    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
278        as not to get warnings when autogen.sh is called. Also changed
279        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
280    
281    44. To help people who use pcregrep to scan files containing exceedingly long
282        lines, the following changes have been made:
283    
284        (a) The default value of the buffer size parameter has been increased from
285            8K to 20K. (The actual buffer used is three times this size.)
286    
287        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
288            PCRE is built.
289    
290        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
291            to be set at run time.
292    
293        (d) Numerical values in pcregrep options can be followed by K or M, for
294            example --buffer-size=50K.
295    
296        (e) If a line being scanned overflows pcregrep's buffer, an error is now
297            given and the return code is set to 2.
298    
299    45. Add a pointer to the latest mark to the callout data block.
300    
301    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
302        partial match of an empty string instead of no match. This was specific to
303        the use of ".".
304    
305    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
306        complete match instead of a partial match. This bug was dependent on both
307        the PCRE_UTF8 and PCRE_DOTALL options being set.
308    
309    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
310        starting byte set, because \b was not being ignored.
311    
312    
313  Version 8.12 15-Jan-2011  Version 8.12 15-Jan-2011

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