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revision 602 by ph10, Wed May 25 08:29:03 2011 UTC revision 780 by ph10, Fri Dec 2 11:39:21 2011 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.13 30-Apr-2011  Version 8.21
5    ------------
6    
7    1.  Updating the JIT compiler.
8    
9    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
10        are added as well.
11    
12    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
13        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
14        calling _pcre_jit_exec. Some extra comments are added.
15    
16    4.  Mark settings inside atomic groups that do not contain any capturing
17        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
18        was introduced by change 18 for 8.20.
19    
20    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
21        ECMA-262 standard.
22    
23    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
24        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
25        This bug was probably introduced by change 9 of 8.13.
26    
27    7.  While fixing 6 above, I noticed that a number of other items were being
28        incorrectly rejected as "not fixed length". This arose partly because newer
29        opcodes had not been added to the fixed-length checking code. I have (a)
30        corrected the bug and added tests for these items, and (b) arranged for an
31        error to occur if an unknown opcode is encountered while checking for fixed
32        length instead of just assuming "not fixed length". The items that were
33        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
34        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
35        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
36    
37    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
38        being incorrectly compiled and would have given unpredicatble results.
39    
40    9.  A possessively repeated subpattern with minimum repeat count greater than
41        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
42        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
43        the first (A) could occur when it should not.
44    
45    10. Add a cast and remove a redundant test from the code.
46    
47    11. JIT should use pcre_malloc/pcre_free for allocation.
48    
49    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
50        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
51        is anything other than /usr, -L is still shown).
52    
53    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
54    
55    14. Perl does not support \N without a following name in a [] class; PCRE now
56        also gives an error.
57    
58    15. If a forward reference was repeated with an upper limit of around 2000,
59        it caused the error "internal error: overran compiling workspace". The
60        maximum number of forward references (including repeats) was limited by the
61        internal workspace, and dependent on the LINK_SIZE. The code has been
62        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
63        the default depends on LINK_SIZE. There is a new upper limit (for safety)
64        of around 200,000 forward references. While doing this, I also speeded up
65        the filling in of repeated forward references.
66    
67    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
68        incorrectly expecting the subject to contain another "a" after the start.
69    
70    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
71        in the match, the SKIP should be ignored. This was not happening; instead
72        the SKIP was being treated as NOMATCH. For patterns such as
73        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
74        tested.
75    
76    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
77        now much more compatible with Perl, in particular in cases where the result
78        is a non-match for a non-anchored pattern. For example, if
79        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
80        "m", where previously it did not return a name. A side effect of this
81        change is that for partial matches, the last encountered mark name is
82        returned, as for non matches. A number of tests that were previously not
83        Perl-compatible have been moved into the Perl-compatible test files. The
84        refactoring has had the pleasing side effect of removing one argument from
85        the match() function, thus reducing its stack requirements.
86    
87    19. If the /S+ option was used in pcretest to study a pattern using JIT,
88        subsequent uses of /S (without +) incorrectly behaved like /S+.
89    
90    21. Retrieve executable code size support for the JIT compiler and fixing
91        some warnings.
92    
93    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
94        not work when the shorter character appeared right at the end of the
95        subject string.
96    
97    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
98        systems.
99    
100    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
101        output it when the /M option is used in pcretest.
102    
103    
104    Version 8.20 21-Oct-2011
105    ------------------------
106    
107    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
108        a POSIX class. After further experiments with Perl, which convinced me that
109        Perl has bugs and confusions, a closing square bracket is no longer allowed
110        in a POSIX name. This bug also affected patterns with classes that started
111        with full stops.
112    
113    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
114        captured substring, but while checking the failing first alternative,
115        substring 1 is temporarily captured. If the output vector supplied to
116        pcre_exec() was not big enough for this capture, the yield of the function
117        was still zero ("insufficient space for captured substrings"). This cannot
118        be totally fixed without adding another stack variable, which seems a lot
119        of expense for a edge case. However, I have improved the situation in cases
120        such as /(a)(b)x|abc/ matched against "abc", where the return code
121        indicates that fewer than the maximum number of slots in the ovector have
122        been set.
123    
124    3.  Related to (2) above: when there are more back references in a pattern than
125        slots in the output vector, pcre_exec() uses temporary memory during
126        matching, and copies in the captures as far as possible afterwards. It was
127        using the entire output vector, but this conflicts with the specification
128        that only 2/3 is used for passing back captured substrings. Now it uses
129        only the first 2/3, for compatibility. This is, of course, another edge
130        case.
131    
132    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
133        main code base, and can be used by building with --enable-jit. When this is
134        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
135        runtime --no-jit option is given.
136    
137    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
138        ovector, the return from the function was zero, implying that there were
139        other matches that did not fit. The correct "exactly full" value is now
140        returned.
141    
142    6.  If a subpattern that was called recursively or as a subroutine contained
143        (*PRUNE) or any other control that caused it to give a non-standard return,
144        invalid errors such as "Error -26 (nested recursion at the same subject
145        position)" or even infinite loops could occur.
146    
147    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
148        computing the minimum length on reaching *ACCEPT, and so ended up with the
149        wrong value of 1 rather than 0. Further investigation indicates that
150        computing a minimum subject length in the presence of *ACCEPT is difficult
151        (think back references, subroutine calls), and so I have changed the code
152        so that no minimum is registered for a pattern that contains *ACCEPT.
153    
154    8.  If (*THEN) was present in the first (true) branch of a conditional group,
155        it was not handled as intended. [But see 16 below.]
156    
157    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
158        Sheri Pierce.
159    
160    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
161        the first byte in a match must be "a".
162    
163    11. Change 17 for 8.13 increased the recursion depth for patterns like
164        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
165        pattern contains any instances of (*THEN). If it does not, the old
166        optimizations are restored. It would be nice to do this on a per-group
167        basis, but at the moment that is not feasible.
168    
169    12. In some environments, the output of pcretest -C is CRLF terminated. This
170        broke RunTest's code that checks for the link size. A single white space
171        character after the value is now allowed for.
172    
173    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
174        For "fr", it uses the Windows-specific input and output files.
175    
176    14. If (*THEN) appeared in a group that was called recursively or as a
177        subroutine, it did not work as intended. [But see next item.]
178    
179    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
180        pattern fragments (but not containing any | characters). If A and B are
181        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
182        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
183        D. In other words, Perl considers parentheses that do not contain any |
184        characters to be part of a surrounding alternative, whereas PCRE was
185        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
186        differently. PCRE now behaves in the same way as Perl, except in the case
187        of subroutine/recursion calls such as (?1) which have in any case always
188        been different (but PCRE had them first :-).
189    
190    16. Related to 15 above: Perl does not treat the | in a conditional group as
191        creating alternatives. Such a group is treated in the same way as an
192        ordinary group without any | characters when processing (*THEN). PCRE has
193        been changed to match Perl's behaviour.
194    
195    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
196        RunGrepTest script failed.
197    
198    18. Change 22 for version 13 caused atomic groups to use more stack. This is
199        inevitable for groups that contain captures, but it can lead to a lot of
200        stack use in large patterns. The old behaviour has been restored for atomic
201        groups that do not contain any capturing parentheses.
202    
203    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
204        suppress the check for a minimum subject length at run time. (If it was
205        given to pcre_exec() or pcre_dfa_exec() it did work.)
206    
207    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
208        fail to work when decoding hex characters in data strings in EBCDIC
209        environments.
210    
211    21. It appears that in at least one Mac OS environment, the isxdigit() function
212        is implemented as a macro that evaluates to its argument more than once,
213        contravening the C 90 Standard (I haven't checked a later standard). There
214        was an instance in pcretest which caused it to go wrong when processing
215        \x{...} escapes in subject strings. The has been rewritten to avoid using
216        things like p++ in the argument of isxdigit().
217    
218    
219    Version 8.13 16-Aug-2011
220  ------------------------  ------------------------
221    
222  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 235  Version 8.13 30-Apr-2011
235      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
236      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
237      left).      left).
238    
239  5.  Comprehensive information about what went wrong is now returned by  5.  Comprehensive information about what went wrong is now returned by
240      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
241      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
242      the failing character and a reason code are placed in the vector.      the failing character and a reason code are placed in the vector.
243    
244  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
245      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
246      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
247      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
248      pcre_exec() and pcre_dfa_exec().      pcre_exec() and pcre_dfa_exec().
249    
250  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
251      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
252      failure, the offset and reason code are output.      failure, the offset and reason code are output.
253    
254  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
255      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
256      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
257      two characters as a single entity when going forwards), conflicts with the      two characters as a single entity when going forwards), conflicts with the
258      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
259      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour      behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
260      has been changed.      has been changed.
261    
262  9.  Some internal refactoring has changed the processing so that the handling  9.  Some internal refactoring has changed the processing so that the handling
263      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
264      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
265      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,
266      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
267      argument for the match() function, which reduces its stack requirements      argument for the match() function, which reduces its stack requirements
268      slightly. This change also fixes an incompatibility with Perl: the pattern      slightly. This change also fixes an incompatibility with Perl: the pattern
269      (?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.
270    
271    10. More internal refactoring has drastically reduced the number of recursive
272        calls to match() for possessively repeated groups such as (abc)++ when
273        using pcre_exec().
274    
275    11. While implementing 10, a number of bugs in the handling of groups were
276        discovered and fixed:
277    
278        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
279        (a|)*(?1) gave a compile-time internal error.
280        ((a|)+)+  did not notice that the outer group could match an empty string.
281        (^a|^)+   was not marked as anchored.
282        (.*a|.*)+ was not marked as matching at start or after a newline.
283    
284    12. Yet more internal refactoring has removed another argument from the match()
285        function. Special calls to this function are now indicated by setting a
286        value in a variable in the "match data" data block.
287    
288    13. Be more explicit in pcre_study() instead of relying on "default" for
289        opcodes that mean there is no starting character; this means that when new
290        ones are added and accidentally left out of pcre_study(), testing should
291        pick them up.
292    
293    14. The -s option of pcretest has been documented for ages as being an old
294        synonym of -m (show memory usage). I have changed it to mean "force study
295        for every regex", that is, assume /S for every regex. This is similar to -i
296        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
297        using it. It makes it easier to run collections of tests with and without
298        study enabled, and thereby test pcre_study() more easily. All the standard
299        tests are now run with and without -s (but some patterns can be marked as
300        "never study" - see 20 below).
301    
302    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
303        restoration of the capturing data to the outer values was not happening
304        correctly.
305    
306    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
307        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
308        pattern had matched an empty string, and so incorrectly returned a no
309        match.
310    
311    17. There was optimizing code for the last branch of non-capturing parentheses,
312        and also for the obeyed branch of a conditional subexpression, which used
313        tail recursion to cut down on stack usage. Unfortunately, now that there is
314        the possibility of (*THEN) occurring in these branches, tail recursion is
315        no longer possible because the return has to be checked for (*THEN). These
316        two optimizations have therefore been removed. [But see 8.20/11 above.]
317    
318    18. If a pattern containing \R was studied, it was assumed that \R always
319        matched two bytes, thus causing the minimum subject length to be
320        incorrectly computed because \R can also match just one byte.
321    
322    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
323        was incorrectly computed.
324    
325    20. If /S is present twice on a test pattern in pcretest input, it now
326        *disables* studying, thereby overriding the use of -s on the command line
327        (see 14 above). This is necessary for one or two tests to keep the output
328        identical in both cases.
329    
330    21. When (*ACCEPT) was used in an assertion that matched an empty string and
331        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
332    
333    22. When an atomic group that contained a capturing parenthesis was
334        successfully matched, but the branch in which it appeared failed, the
335        capturing was not being forgotten if a higher numbered group was later
336        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
337        group 1 to "a", when in fact it should be unset. This applied to multi-
338        branched capturing and non-capturing groups, repeated or not, and also to
339        positive assertions (capturing in negative assertions does not happen
340        in PCRE) and also to nested atomic groups.
341    
342    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
343        subject after a captured substring, to make it easier to tell which of a
344        number of identical substrings has been captured.
345    
346    24. The way atomic groups are processed by pcre_exec() has been changed so that
347        if they are repeated, backtracking one repetition now resets captured
348        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
349        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
350        "aaa". Previously, it would have been "a". As part of this code
351        refactoring, the way recursive calls are handled has also been changed.
352    
353    25. If an assertion condition captured any substrings, they were not passed
354        back unless some other capturing happened later. For example, if
355        (?(?=(a))a) was matched against "a", no capturing was returned.
356    
357    26. When studying a pattern that contained subroutine calls or assertions,
358        the code for finding the minimum length of a possible match was handling
359        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
360        group 1 called group 2 while simultaneously a separate group 2 called group
361        1). A stack overflow occurred in this case. I have fixed this by limiting
362        the recursion depth to 10.
363    
364    27. Updated RunTest.bat in the distribution to the version supplied by Tom
365        Fortmann. This supports explicit test numbers on the command line, and has
366        argument validation and error reporting.
367    
368    28. An instance of \X with an unlimited repeat could fail if at any point the
369        first character it looked at was a mark character.
370    
371    29. Some minor code refactoring concerning Unicode properties and scripts
372        should reduce the stack requirement of match() slightly.
373    
374    30. Added the '=' option to pcretest to check the setting of unused capturing
375        slots at the end of the pattern, which are documented as being -1, but are
376        not included in the return count.
377    
378    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
379        compiled something random. Now it gives a compile-time error (as does
380        Perl).
381    
382    32. A *MARK encountered during the processing of a positive assertion is now
383        recorded and passed back (compatible with Perl).
384    
385    33. If --only-matching or --colour was set on a pcregrep call whose pattern
386        had alternative anchored branches, the search for a second match in a line
387        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
388        matched the line "0102" twice. The same bug affected patterns that started
389        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
390        twice.
391    
392    34. Previously, PCRE did not allow quantification of assertions. However, Perl
393        does, and because of capturing effects, quantifying parenthesized
394        assertions may at times be useful. Quantifiers are now allowed for
395        parenthesized assertions.
396    
397    35. A minor code tidy in pcre_compile() when checking options for \R usage.
398    
399    36. \g was being checked for fancy things in a character class, when it should
400        just be a literal "g".
401    
402    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
403        appearance of a nested POSIX class supersedes an apparent external class.
404        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
405        unescaped square brackets may also appear as part of class names. For
406        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
407        more like Perl. (But see 8.20/1 above.)
408    
409    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
410        was because it thought it was \N{name}, which is not supported).
411    
412    39. Add minix to OS list not supporting the -S option in pcretest.
413    
414    40. PCRE tries to detect cases of infinite recursion at compile time, but it
415        cannot analyze patterns in sufficient detail to catch mutual recursions
416        such as ((?1))((?2)). There is now a runtime test that gives an error if a
417        subgroup is called recursively as a subpattern for a second time at the
418        same position in the subject string. In previous releases this might have
419        been caught by the recursion limit, or it might have run out of stack.
420    
421    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
422        happen only once. PCRE was, however incorrectly giving a compile time error
423        "recursive call could loop indefinitely" because it cannot analyze the
424        pattern in sufficient detail. The compile time test no longer happens when
425        PCRE is compiling a conditional subpattern, but actual runaway loops are
426        now caught at runtime (see 40 above).
427    
428    42. It seems that Perl allows any characters other than a closing parenthesis
429        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
430        has been changed to be the same.
431    
432    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
433        as not to get warnings when autogen.sh is called. Also changed
434        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
435    
436    44. To help people who use pcregrep to scan files containing exceedingly long
437        lines, the following changes have been made:
438    
439        (a) The default value of the buffer size parameter has been increased from
440            8K to 20K. (The actual buffer used is three times this size.)
441    
442        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
443            PCRE is built.
444    
445        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
446            to be set at run time.
447    
448        (d) Numerical values in pcregrep options can be followed by K or M, for
449            example --buffer-size=50K.
450    
451        (e) If a line being scanned overflows pcregrep's buffer, an error is now
452            given and the return code is set to 2.
453    
454    45. Add a pointer to the latest mark to the callout data block.
455    
456    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
457        partial match of an empty string instead of no match. This was specific to
458        the use of ".".
459    
460    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
461        complete match instead of a partial match. This bug was dependent on both
462        the PCRE_UTF8 and PCRE_DOTALL options being set.
463    
464    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
465        starting byte set, because \b was not being ignored.
466    
467    
468  Version 8.12 15-Jan-2011  Version 8.12 15-Jan-2011
469  ------------------------  ------------------------

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