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revision 622 by ph10, Mon Jul 18 10:46:51 2011 UTC revision 699 by ph10, Tue Sep 20 10:46:54 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    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.  1.  The Unicode data tables have been updated to Unicode 6.0.0.
# Line 20  Version 8.13 30-Apr-2011 Line 72  Version 8.13 30-Apr-2011
72      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
73      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
74      left).      left).
75    
76  5.  Comprehensive information about what went wrong is now returned by  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      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      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.      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  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      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      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      enough not to be a problem. It makes the returned offset consistent with
85      pcre_exec() and pcre_dfa_exec().      pcre_exec() and pcre_dfa_exec().
86    
87  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
88      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
89      failure, the offset and reason code are output.      failure, the offset and reason code are output.
90    
91  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
92      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
93      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
94      two characters as a single entity when going forwards), conflicts with the      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      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      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
97      has been changed.      has been changed.
98    
99  9.  Some internal refactoring has changed the processing so that the handling  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      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      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,      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      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      argument for the match() function, which reduces its stack requirements
105      slightly. This change also fixes an incompatibility with Perl: the pattern      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.      (?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  10. More internal refactoring has drastically reduced the number of recursive
109      calls to match() for possessively repeated groups such as (abc)++ when      calls to match() for possessively repeated groups such as (abc)++ when
110      using pcre_exec().      using pcre_exec().
111    
112  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
113      discovered and fixed:      discovered and fixed:
114    
115      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
116      (a|)*(?1) gave a compile-time internal error.      (a|)*(?1) gave a compile-time internal error.
117      ((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.
118      (^a|^)+   was not marked as anchored.      (^a|^)+   was not marked as anchored.
119      (.*a|.*)+ was not marked as matching at start or after a newline.      (.*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()  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      function. Special calls to this function are now indicated by setting a
123      value in a variable in the "match data" data block.      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  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      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      ones are added and accidentally left out of pcre_study(), testing should
128      pick them up.      pick them up.
129    
130  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
131      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
132      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
133      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
134      using it. It makes it easier to run collections of tests with and without      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      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      tests are now run with and without -s (but some patterns can be marked as
137      "never study" - see 20 below).      "never study" - see 20 below).
138    
139  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
140      restoration of the capturing data to the outer values was not happening      restoration of the capturing data to the outer values was not happening
141      correctly.      correctly.
142    
143  16. If a recursively called subpattern ended with (*ACCEPT) and matched an  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      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      pattern had matched an empty string, and so incorrectly returned a no
146      match.      match.
147    
148  17. There was optimizing code for the last branch of non-capturing parentheses,  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      and also for the obeyed branch of a conditional subexpression, which used
150      tail recursion to cut down on stack usage. Unfortunately, not that there is      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      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      no longer possible because the return has to be checked for (*THEN). These
153      two optimizations have therefore been removed.      two optimizations have therefore been removed.
154    
155  18. If a pattern containing \R was studied, it was assumed that \R always  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      matched two bytes, thus causing the minimum subject length to be
157      incorrectly computed because \R can also match just one byte.      incorrectly computed because \R can also match just one byte.
158    
159  19. If a pattern containing (*ACCEPT) was studied, the minimum subject length  19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
160      was incorrectly computed.      was incorrectly computed.
161    
162  20. If /S is present twice on a test pattern in pcretest input, it *disables*  20. If /S is present twice on a test pattern in pcretest input, it now
163      studying, thereby overriding the use of -s on the command line. This is      *disables* studying, thereby overriding the use of -s on the command line
164      necessary for one or two tests to keep the output identical in both cases.      (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  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.      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  22. When an atomic group that contained a capturing parenthesis was
171      successfully matched, but the branch in which it appeared failed, the      successfully matched, but the branch in which it appeared failed, the
172      capturing was not being forgotten if a higher numbered group was later      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      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-      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      branched capturing and non-capturing groups, repeated or not, and also to
176      positive assertions (capturing in negative assertions is not well defined      positive assertions (capturing in negative assertions does not happen
177      in PCRE) and also to nested atomic groups.      in PCRE) and also to nested atomic groups.
178    
179  23. Add the ++ qualifier feature to pcretest, to show the remainder of the  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      subject after a captured substring, to make it easier to tell which of a
181      number of identical substrings has been captured).      number of identical substrings has been captured.
182    
183  24. The way atomic groups are processed by pcre_exec() has been changed so that  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      if they are repeated, backtracking one repetition now resets captured
185      values correctly. For example, if ((?>(a+)b)+aabab) is matched against      values correctly. For example, if ((?>(a+)b)+aabab) is matched against
186      "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as      "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      "aaa". Previously, it would have been "a". As part of this code
188      refactoring, the way recursive calls are handled has also been changed.      refactoring, the way recursive calls are handled has also been changed.
189    
190  24. If an assertion condition captured any substrings, they were not passed  25. If an assertion condition captured any substrings, they were not passed
191      back unless some other capturing happened later. For example, if      back unless some other capturing happened later. For example, if
192      (?(?=(a))a) was matched against "a", no capturing was returned.      (?(?=(a))a) was matched against "a", no capturing was returned.
193    
194  25. When studying a pattern that contained subroutine calls or assertions,  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      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      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      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      1). A stack overflow occurred in this case. I have fixed this by limiting
199      the recursion depth to 10.      the recursion depth to 10.
200    
201  26. Updated RunTest.bat in the distribution to the version supplied by Tom  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      Fortmann. This supports explicit test numbers on the command line, and has
203      argument validation and error reporting.      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  Version 8.12 15-Jan-2011

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