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revision 638 by ph10, Mon Jul 25 09:41:19 2011 UTC revision 734 by ph10, Wed Oct 12 16:35:29 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 10-Oct-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. [But see 16 below.]
56    
57    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
58        Sheri 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    11. Change 17 for 8.13 increased the recursion depth for patterns like
64        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
65        pattern contains any instances of (*THEN). If it does not, the old
66        optimizations are restored. It would be nice to do this on a per-group
67        basis, but at the moment that is not feasible.
68    
69    12. In some environments, the output of pcretest -C is CRLF terminated. This
70        broke RunTest's code that checks for the link size. A single white space
71        after the value is now allowed for.
72    
73    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
74        For "fr", it uses the Windows-specific input and output files.
75    
76    14. If (*THEN) appeared in a group that was called recursively or as a
77        subroutine, it did not work as intended. [But see next item.]
78    
79    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
80        pattern fragments (but not containing any | characters). If A and B are
81        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
82        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
83        D. In other words, Perl considers parentheses that do not contain any |
84        characters to be part of a surrounding alternative, whereas PCRE was
85        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
86        differently. PCRE now behaves in the same way as Perl, except in the case
87        of subroutine/recursion calls such as (?1) which have in any case always
88        been different (but PCRE had them first :-).
89    
90    16. Related to 15 above: Perl does not treat the | in a conditional group as
91        creating alternatives. Such a group is treated in the same way as an
92        ordinary group without any | characters when processing (*THEN). PCRE has
93        been changed to match Perl's behaviour.
94    
95    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
96        RunGrepTest script failed.
97    
98    18. Change 22 for version 13 caused atomic groups to use more stack. This is
99        inevitable for groups that contain captures, but it can lead to a lot of
100        stack use in large patterns. The old behaviour has been restored for atomic
101        groups that do not contain any capturing parentheses.
102    
103    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
104        suppress the check for a minimum subject length at run time. (If it was
105        given to pcre_exec() or pcre_dfa_exec() it did work.)
106    
107    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
108        fail to work when decoding hex characters in data strings in EBCDIC
109        environments.
110    
111    
112    Version 8.13 16-Aug-2011
113  ------------------------  ------------------------
114    
115  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 128  Version 8.13 30-Apr-2011
128      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
129      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
130      left).      left).
131    
132  5.  Comprehensive information about what went wrong is now returned by  5.  Comprehensive information about what went wrong is now returned by
133      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
134      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
135      the failing character and a reason code are placed in the vector.      the failing character and a reason code are placed in the vector.
136    
137  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
138      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
139      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
140      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
141      pcre_exec() and pcre_dfa_exec().      pcre_exec() and pcre_dfa_exec().
142    
143  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
144      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
145      failure, the offset and reason code are output.      failure, the offset and reason code are output.
146    
147  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
148      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
149      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
150      two characters as a single entity when going forwards), conflicts with the      two characters as a single entity when going forwards), conflicts with the
151      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
152      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
153      has been changed.      has been changed.
154    
155  9.  Some internal refactoring has changed the processing so that the handling  9.  Some internal refactoring has changed the processing so that the handling
156      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
157      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
158      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,
159      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
160      argument for the match() function, which reduces its stack requirements      argument for the match() function, which reduces its stack requirements
161      slightly. This change also fixes an incompatibility with Perl: the pattern      slightly. This change also fixes an incompatibility with Perl: the pattern
162      (?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.
163    
164  10. More internal refactoring has drastically reduced the number of recursive  10. More internal refactoring has drastically reduced the number of recursive
165      calls to match() for possessively repeated groups such as (abc)++ when      calls to match() for possessively repeated groups such as (abc)++ when
166      using pcre_exec().      using pcre_exec().
167    
168  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
169      discovered and fixed:      discovered and fixed:
170    
171      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).      (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
172      (a|)*(?1) gave a compile-time internal error.      (a|)*(?1) gave a compile-time internal error.
173      ((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.
174      (^a|^)+   was not marked as anchored.      (^a|^)+   was not marked as anchored.
175      (.*a|.*)+ was not marked as matching at start or after a newline.      (.*a|.*)+ was not marked as matching at start or after a newline.
176    
177  12. Yet more internal refactoring has removed another argument from the match()  12. Yet more internal refactoring has removed another argument from the match()
178      function. Special calls to this function are now indicated by setting a      function. Special calls to this function are now indicated by setting a
179      value in a variable in the "match data" data block.      value in a variable in the "match data" data block.
180    
181  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
182      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
183      ones are added and accidentally left out of pcre_study(), testing should      ones are added and accidentally left out of pcre_study(), testing should
184      pick them up.      pick them up.
185    
186  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
187      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
188      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
189      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
190      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
191      study enabled, and thereby test pcre_study() more easily. All the standard      study enabled, and thereby test pcre_study() more easily. All the standard
192      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
193      "never study" - see 20 below).      "never study" - see 20 below).
194    
195  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
196      restoration of the capturing data to the outer values was not happening      restoration of the capturing data to the outer values was not happening
197      correctly.      correctly.
198    
199  16. If a recursively called subpattern ended with (*ACCEPT) and matched an  16. If a recursively called subpattern ended with (*ACCEPT) and matched an
200      empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole      empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
201      pattern had matched an empty string, and so incorrectly returned a no      pattern had matched an empty string, and so incorrectly returned a no
202      match.      match.
203    
204  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,
205      and also for the obeyed branch of a conditional subexpression, which used      and also for the obeyed branch of a conditional subexpression, which used
206      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
207      the possibility of (*THEN) occurring in these branches, tail recursion is      the possibility of (*THEN) occurring in these branches, tail recursion is
208      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
209      two optimizations have therefore been removed.      two optimizations have therefore been removed. [But see 8.20/11 above.]
210    
211  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
212      matched two bytes, thus causing the minimum subject length to be      matched two bytes, thus causing the minimum subject length to be
213      incorrectly computed because \R can also match just one byte.      incorrectly computed because \R can also match just one byte.
214    
215  19. If a pattern containing (*ACCEPT) was studied, the minimum subject length  19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
216      was incorrectly computed.      was incorrectly computed.
217    
218  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
219      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
220      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
221        identical in both cases.
222    
223  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
224      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.
225    
226  22. When an atomic group that contained a capturing parenthesis was  22. When an atomic group that contained a capturing parenthesis was
227      successfully matched, but the branch in which it appeared failed, the      successfully matched, but the branch in which it appeared failed, the
228      capturing was not being forgotten if a higher numbered group was later      capturing was not being forgotten if a higher numbered group was later
229      captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing      captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
230      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-
231      branched capturing and non-capturing groups, repeated or not, and also to      branched capturing and non-capturing groups, repeated or not, and also to
232      positive assertions (capturing in negative assertions is not well defined      positive assertions (capturing in negative assertions does not happen
233      in PCRE) and also to nested atomic groups.      in PCRE) and also to nested atomic groups.
234    
235  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
236      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
237      number of identical substrings has been captured).      number of identical substrings has been captured.
238    
239  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
240      if they are repeated, backtracking one repetition now resets captured      if they are repeated, backtracking one repetition now resets captured
241      values correctly. For example, if ((?>(a+)b)+aabab) is matched against      values correctly. For example, if ((?>(a+)b)+aabab) is matched against
242      "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as      "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
243      "aaa". Previously, it would have been "a". As part of this code      "aaa". Previously, it would have been "a". As part of this code
244      refactoring, the way recursive calls are handled has also been changed.      refactoring, the way recursive calls are handled has also been changed.
245    
246  24. If an assertion condition captured any substrings, they were not passed  25. If an assertion condition captured any substrings, they were not passed
247      back unless some other capturing happened later. For example, if      back unless some other capturing happened later. For example, if
248      (?(?=(a))a) was matched against "a", no capturing was returned.      (?(?=(a))a) was matched against "a", no capturing was returned.
249    
250  25. When studying a pattern that contained subroutine calls or assertions,  26. When studying a pattern that contained subroutine calls or assertions,
251      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
252      direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where      direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
253      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
254      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
255      the recursion depth to 10.      the recursion depth to 10.
256    
257  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
258      Fortmann. This supports explicit test numbers on the command line, and has      Fortmann. This supports explicit test numbers on the command line, and has
259      argument validation and error reporting.      argument validation and error reporting.
260    
261  27. An instance of \X with an unlimited repeat could fail if at any point the  28. An instance of \X with an unlimited repeat could fail if at any point the
262      first character it looked at was a mark character.      first character it looked at was a mark character.
263    
264  28. Some minor code refactoring concerning Unicode properties and scripts  29. Some minor code refactoring concerning Unicode properties and scripts
265      should reduce the stack requirement of match() slightly.      should reduce the stack requirement of match() slightly.
266    
267  29. Added the '=' option to pcretest to check the setting of unused capturing  30. Added the '=' option to pcretest to check the setting of unused capturing
268      slots at the end of the pattern, which are documented as being -1, but are      slots at the end of the pattern, which are documented as being -1, but are
269      not included in the return count.      not included in the return count.
270    
271  30. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE  31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
272      compiled something random. Now it gives a compile-time error (as does      compiled something random. Now it gives a compile-time error (as does
273      Perl).      Perl).
274    
275  31. A *MARK encountered during the processing of a positive assertion is now  32. A *MARK encountered during the processing of a positive assertion is now
276      recorded and passed back (compatible with Perl).      recorded and passed back (compatible with Perl).
277    
278  32. If --only-matching or --colour was set on a pcregrep call whose pattern  33. If --only-matching or --colour was set on a pcregrep call whose pattern
279      had alternative anchored branches, the search for a second match in a line      had alternative anchored branches, the search for a second match in a line
280      was done as if at the line start. Thus, for example, /^01|^02/ incorrectly      was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
281      matched the line "0102" twice. The same bug affected patterns that started      matched the line "0102" twice. The same bug affected patterns that started
282      with a backwards assertion. For example /\b01|\b02/ also matched "0102"      with a backwards assertion. For example /\b01|\b02/ also matched "0102"
283      twice.      twice.
284    
285  33. Previously, PCRE did not allow quantification of assertions. However, Perl  34. Previously, PCRE did not allow quantification of assertions. However, Perl
286      does, and because of capturing effects, quantifying parenthesized      does, and because of capturing effects, quantifying parenthesized
287      assertions may at times be useful. Quantifiers are now allowed for      assertions may at times be useful. Quantifiers are now allowed for
288      parenthesized assertions.      parenthesized assertions.
289    
290  34. A minor code tidy in pcre_compile() when checking options for \R usage.  35. A minor code tidy in pcre_compile() when checking options for \R usage.
291    
292    36. \g was being checked for fancy things in a character class, when it should
293        just be a literal "g".
294    
295    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
296        appearance of a nested POSIX class supersedes an apparent external class.
297        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
298        unescaped square brackets may also appear as part of class names. For
299        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
300        more like Perl. (But see 8.20/1 above.)
301    
302    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
303        was because it thought it was \N{name}, which is not supported).
304    
305    39. Add minix to OS list not supporting the -S option in pcretest.
306    
307    40. PCRE tries to detect cases of infinite recursion at compile time, but it
308        cannot analyze patterns in sufficient detail to catch mutual recursions
309        such as ((?1))((?2)). There is now a runtime test that gives an error if a
310        subgroup is called recursively as a subpattern for a second time at the
311        same position in the subject string. In previous releases this might have
312        been caught by the recursion limit, or it might have run out of stack.
313    
314    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
315        happen only once. PCRE was, however incorrectly giving a compile time error
316        "recursive call could loop indefinitely" because it cannot analyze the
317        pattern in sufficient detail. The compile time test no longer happens when
318        PCRE is compiling a conditional subpattern, but actual runaway loops are
319        now caught at runtime (see 40 above).
320    
321    42. It seems that Perl allows any characters other than a closing parenthesis
322        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
323        has been changed to be the same.
324    
325    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
326        as not to get warnings when autogen.sh is called. Also changed
327        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
328    
329    44. To help people who use pcregrep to scan files containing exceedingly long
330        lines, the following changes have been made:
331    
332        (a) The default value of the buffer size parameter has been increased from
333            8K to 20K. (The actual buffer used is three times this size.)
334    
335        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
336            PCRE is built.
337    
338        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
339            to be set at run time.
340    
341        (d) Numerical values in pcregrep options can be followed by K or M, for
342            example --buffer-size=50K.
343    
344        (e) If a line being scanned overflows pcregrep's buffer, an error is now
345            given and the return code is set to 2.
346    
347    45. Add a pointer to the latest mark to the callout data block.
348    
349    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
350        partial match of an empty string instead of no match. This was specific to
351        the use of ".".
352    
353    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
354        complete match instead of a partial match. This bug was dependent on both
355        the PCRE_UTF8 and PCRE_DOTALL options being set.
356    
357    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
358        starting byte set, because \b was not being ignored.
359    
360    
361  Version 8.12 15-Jan-2011  Version 8.12 15-Jan-2011

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