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revision 608 by ph10, Sun Jun 12 16:25:55 2011 UTC revision 697 by ph10, Mon Sep 19 12:28:24 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 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    
53    Version 8.13 16-Aug-2011
54  ------------------------  ------------------------
55    
56  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 69  Version 8.13 30-Apr-2011
69      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
70      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
71      left).      left).
72    
73  5.  Comprehensive information about what went wrong is now returned by  5.  Comprehensive information about what went wrong is now returned by
74      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
75      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
76      the failing character and a reason code are placed in the vector.      the failing character and a reason code are placed in the vector.
77    
78  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
79      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
80      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
81      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
82      pcre_exec() and pcre_dfa_exec().      pcre_exec() and pcre_dfa_exec().
83    
84  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
85      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
86      failure, the offset and reason code are output.      failure, the offset and reason code are output.
87    
88  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
89      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
90      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
91      two characters as a single entity when going forwards), conflicts with the      two characters as a single entity when going forwards), conflicts with the
92      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
93      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
94      has been changed.      has been changed.
95    
96  9.  Some internal refactoring has changed the processing so that the handling  9.  Some internal refactoring has changed the processing so that the handling
97      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
98      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
99      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,
100      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
101      argument for the match() function, which reduces its stack requirements      argument for the match() function, which reduces its stack requirements
102      slightly. This change also fixes an incompatibility with Perl: the pattern      slightly. This change also fixes an incompatibility with Perl: the pattern
103      (?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.
104    
105  10. More internal refactoring has drastically reduced the number of recursive  10. More internal refactoring has drastically reduced the number of recursive
106      calls to match() for possessively repeated groups such as (abc)++ when      calls to match() for possessively repeated groups such as (abc)++ when
107      using pcre_exec().      using pcre_exec().
108    
109  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
110      discovered and fixed:      discovered and fixed:
111    
112      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
113      (a|)*(?1) gave a compile-time internal error.      (a|)*(?1) gave a compile-time internal error.
114      ((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.
115      (^a|^)+   was not marked as anchored.      (^a|^)+   was not marked as anchored.
116      (.*a|.*)+ was not marked as matching at start or after a newline.      (.*a|.*)+ was not marked as matching at start or after a newline.
117    
118  12. Yet more internal refactoring has removed another argument from the match()  12. Yet more internal refactoring has removed another argument from the match()
119      function. Special calls to this function are now indicated by setting a      function. Special calls to this function are now indicated by setting a
120      value in a variable in the "match data" data block.      value in a variable in the "match data" data block.
121    
122  13. Be more explicit in pcre_study() instead of relying on "default" for  13. Be more explicit in pcre_study() instead of relying on "default" for
123      opcodes that mean there is no starting character; this means that when new      opcodes that mean there is no starting character; this means that when new
124      ones are added and accidentally left out of pcre_study(), testing should      ones are added and accidentally left out of pcre_study(), testing should
125      pick them up.      pick them up.
126    
127  14. The -s option of pcretest has been documented for ages as being an old  14. The -s option of pcretest has been documented for ages as being an old
128      synonym of -m (show memory usage). I have changed it to mean "force study      synonym of -m (show memory usage). I have changed it to mean "force study
129      for every regex", that is, assume /S for every regex. This is similar to -i      for every regex", that is, assume /S for every regex. This is similar to -i
130      and -d etc. It's slightly incompatible, but I'm hoping nobody is still      and -d etc. It's slightly incompatible, but I'm hoping nobody is still
131      using it. It makes it easier to run collection of tests with study enabled,      using it. It makes it easier to run collections of tests with and without
132      and thereby test pcre_study() more easily.      study enabled, and thereby test pcre_study() more easily. All the standard
133        tests are now run with and without -s (but some patterns can be marked as
134        "never study" - see 20 below).
135    
136  15. When (*ACCEPT) was used in a subpattern that was called recursively, the  15. When (*ACCEPT) was used in a subpattern that was called recursively, the
137      restoration of the capturing data to the outer values was not happening      restoration of the capturing data to the outer values was not happening
138      correctly.      correctly.
139    
140  16. If a recursively called subpattern ended with (*ACCEPT) and matched an  16. If a recursively called subpattern ended with (*ACCEPT) and matched an
141      empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole      empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
142      pattern had matched an empty string, and so incorrectly returned a no      pattern had matched an empty string, and so incorrectly returned a no
143      match.      match.
144    
145    17. There was optimizing code for the last branch of non-capturing parentheses,
146        and also for the obeyed branch of a conditional subexpression, which used
147        tail recursion to cut down on stack usage. Unfortunately, now that there is
148        the possibility of (*THEN) occurring in these branches, tail recursion is
149        no longer possible because the return has to be checked for (*THEN). These
150        two optimizations have therefore been removed.
151    
152    18. If a pattern containing \R was studied, it was assumed that \R always
153        matched two bytes, thus causing the minimum subject length to be
154        incorrectly computed because \R can also match just one byte.
155    
156    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
157        was incorrectly computed.
158    
159    20. If /S is present twice on a test pattern in pcretest input, it now
160        *disables* studying, thereby overriding the use of -s on the command line
161        (see 14 above). This is necessary for one or two tests to keep the output
162        identical in both cases.
163    
164    21. When (*ACCEPT) was used in an assertion that matched an empty string and
165        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
166    
167    22. When an atomic group that contained a capturing parenthesis was
168        successfully matched, but the branch in which it appeared failed, the
169        capturing was not being forgotten if a higher numbered group was later
170        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
171        group 1 to "a", when in fact it should be unset. This applied to multi-
172        branched capturing and non-capturing groups, repeated or not, and also to
173        positive assertions (capturing in negative assertions does not happen
174        in PCRE) and also to nested atomic groups.
175    
176    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
177        subject after a captured substring, to make it easier to tell which of a
178        number of identical substrings has been captured.
179    
180    24. The way atomic groups are processed by pcre_exec() has been changed so that
181        if they are repeated, backtracking one repetition now resets captured
182        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
183        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
184        "aaa". Previously, it would have been "a". As part of this code
185        refactoring, the way recursive calls are handled has also been changed.
186    
187    25. If an assertion condition captured any substrings, they were not passed
188        back unless some other capturing happened later. For example, if
189        (?(?=(a))a) was matched against "a", no capturing was returned.
190    
191    26. When studying a pattern that contained subroutine calls or assertions,
192        the code for finding the minimum length of a possible match was handling
193        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
194        group 1 called group 2 while simultaneously a separate group 2 called group
195        1). A stack overflow occurred in this case. I have fixed this by limiting
196        the recursion depth to 10.
197    
198    27. Updated RunTest.bat in the distribution to the version supplied by Tom
199        Fortmann. This supports explicit test numbers on the command line, and has
200        argument validation and error reporting.
201    
202    28. An instance of \X with an unlimited repeat could fail if at any point the
203        first character it looked at was a mark character.
204    
205    29. Some minor code refactoring concerning Unicode properties and scripts
206        should reduce the stack requirement of match() slightly.
207    
208    30. Added the '=' option to pcretest to check the setting of unused capturing
209        slots at the end of the pattern, which are documented as being -1, but are
210        not included in the return count.
211    
212    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
213        compiled something random. Now it gives a compile-time error (as does
214        Perl).
215    
216    32. A *MARK encountered during the processing of a positive assertion is now
217        recorded and passed back (compatible with Perl).
218    
219    33. If --only-matching or --colour was set on a pcregrep call whose pattern
220        had alternative anchored branches, the search for a second match in a line
221        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
222        matched the line "0102" twice. The same bug affected patterns that started
223        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
224        twice.
225    
226    34. Previously, PCRE did not allow quantification of assertions. However, Perl
227        does, and because of capturing effects, quantifying parenthesized
228        assertions may at times be useful. Quantifiers are now allowed for
229        parenthesized assertions.
230    
231    35. A minor code tidy in pcre_compile() when checking options for \R usage.
232    
233    36. \g was being checked for fancy things in a character class, when it should
234        just be a literal "g".
235    
236    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
237        appearance of a nested POSIX class supersedes an apparent external class.
238        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
239        unescaped square brackets may also appear as part of class names. For
240        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
241        more like Perl. (But see 8.20/1 above.)
242    
243    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
244        was because it thought it was \N{name}, which is not supported).
245    
246    39. Add minix to OS list not supporting the -S option in pcretest.
247    
248    40. PCRE tries to detect cases of infinite recursion at compile time, but it
249        cannot analyze patterns in sufficient detail to catch mutual recursions
250        such as ((?1))((?2)). There is now a runtime test that gives an error if a
251        subgroup is called recursively as a subpattern for a second time at the
252        same position in the subject string. In previous releases this might have
253        been caught by the recursion limit, or it might have run out of stack.
254    
255    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
256        happen only once. PCRE was, however incorrectly giving a compile time error
257        "recursive call could loop indefinitely" because it cannot analyze the
258        pattern in sufficient detail. The compile time test no longer happens when
259        PCRE is compiling a conditional subpattern, but actual runaway loops are
260        now caught at runtime (see 40 above).
261    
262    42. It seems that Perl allows any characters other than a closing parenthesis
263        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
264        has been changed to be the same.
265    
266    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
267        as not to get warnings when autogen.sh is called. Also changed
268        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
269    
270    44. To help people who use pcregrep to scan files containing exceedingly long
271        lines, the following changes have been made:
272    
273        (a) The default value of the buffer size parameter has been increased from
274            8K to 20K. (The actual buffer used is three times this size.)
275    
276        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
277            PCRE is built.
278    
279        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
280            to be set at run time.
281    
282        (d) Numerical values in pcregrep options can be followed by K or M, for
283            example --buffer-size=50K.
284    
285        (e) If a line being scanned overflows pcregrep's buffer, an error is now
286            given and the return code is set to 2.
287    
288    45. Add a pointer to the latest mark to the callout data block.
289    
290    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
291        partial match of an empty string instead of no match. This was specific to
292        the use of ".".
293    
294    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
295        complete match instead of a partial match. This bug was dependent on both
296        the PCRE_UTF8 and PCRE_DOTALL options being set.
297    
298    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
299        starting byte set, because \b was not being ignored.
300    
301    
302  Version 8.12 15-Jan-2011  Version 8.12 15-Jan-2011
303  ------------------------  ------------------------

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