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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.12 12-Jan-2011  Version 8.20 23-Sep-2011
5    ------------------------
6    
7    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
8        a POSIX class. After further experiments with Perl, which convinced me that
9        Perl has bugs and confusions, a closing square bracket is no longer allowed
10        in a POSIX name. This bug also affected patterns with classes that started
11        with full stops.
12    
13    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
14        captured substring, but while checking the failing first alternative,
15        substring 1 is temporarily captured. If the output vector supplied to
16        pcre_exec() was not big enough for this capture, the yield of the function
17        was still zero ("insufficient space for captured substrings"). This cannot
18        be totally fixed without adding another stack variable, which seems a lot
19        of expense for a edge case. However, I have improved the situation in cases
20        such as /(a)(b)x|abc/ matched against "abc", where the return code
21        indicates that fewer than the maximum number of slots in the ovector have
22        been set.
23    
24    3.  Related to (2) above: when there are more back references in a pattern than
25        slots in the output vector, pcre_exec() uses temporary memory during
26        matching, and copies in the captures as far as possible afterwards. It was
27        using the entire output vector, but this conflicts with the specification
28        that only 2/3 is used for passing back captured substrings. Now it uses
29        only the first 2/3, for compatibility. This is, of course, another edge
30        case.
31    
32    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
33        main code base, and can be used by building with --enable-jit. When this is
34        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
35        runtime --no-jit option is given.
36    
37    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
38        ovector, the return from the function was zero, implying that there were
39        other matches that did not fit. The correct "exactly full" value is now
40        returned.
41    
42    6.  If a subpattern that was called recursively or as a subroutine contained
43        (*PRUNE) or any other control that caused it to give a non-standard return,
44        invalid errors such as "Error -26 (nested recursion at the same subject
45        position)" or even infinite loops could occur.
46    
47    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
48        computing the minimum length on reaching *ACCEPT, and so ended up with the
49        wrong value of 1 rather than 0. Further investigation indicates that
50        computing a minimum subject length in the presence of *ACCEPT is difficult
51        (think back references, subroutine calls), and so I have changed the code
52        so that no minimum is registered for a pattern that contains *ACCEPT.
53    
54    8.  If (*THEN) was present in the first (true) branch of a conditional group,
55        it was not handled as intended. [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    
96    Version 8.13 16-Aug-2011
97    ------------------------
98    
99    1.  The Unicode data tables have been updated to Unicode 6.0.0.
100    
101    2.  Two minor typos in pcre_internal.h have been fixed.
102    
103    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
104        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
105        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
106    
107    4.  There were a number of related bugs in the code for matching backrefences
108        caselessly in UTF-8 mode when codes for the characters concerned were
109        different numbers of bytes. For example, U+023A and U+2C65 are an upper
110        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
111        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
112        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
113        2-byte code at the end of the subject (it thought there wasn't enough data
114        left).
115    
116    5.  Comprehensive information about what went wrong is now returned by
117        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
118        as the output vector has at least 2 elements. The offset of the start of
119        the failing character and a reason code are placed in the vector.
120    
121    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
122        now returned is for the first byte of the failing character, instead of the
123        last byte inspected. This is an incompatible change, but I hope it is small
124        enough not to be a problem. It makes the returned offset consistent with
125        pcre_exec() and pcre_dfa_exec().
126    
127    7.  pcretest now gives a text phrase as well as the error number when
128        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
129        failure, the offset and reason code are output.
130    
131    8.  When \R was used with a maximizing quantifier it failed to skip backwards
132        over a \r\n pair if the subsequent match failed. Instead, it just skipped
133        back over a single character (\n). This seems wrong (because it treated the
134        two characters as a single entity when going forwards), conflicts with the
135        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
136        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
137        has been changed.
138    
139    9.  Some internal refactoring has changed the processing so that the handling
140        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
141        time (the PCRE_DOTALL option was changed this way some time ago: version
142        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
143        which was always a bit of a fudge. It also means that there is one less
144        argument for the match() function, which reduces its stack requirements
145        slightly. This change also fixes an incompatibility with Perl: the pattern
146        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
147    
148    10. More internal refactoring has drastically reduced the number of recursive
149        calls to match() for possessively repeated groups such as (abc)++ when
150        using pcre_exec().
151    
152    11. While implementing 10, a number of bugs in the handling of groups were
153        discovered and fixed:
154    
155        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
156        (a|)*(?1) gave a compile-time internal error.
157        ((a|)+)+  did not notice that the outer group could match an empty string.
158        (^a|^)+   was not marked as anchored.
159        (.*a|.*)+ was not marked as matching at start or after a newline.
160    
161    12. Yet more internal refactoring has removed another argument from the match()
162        function. Special calls to this function are now indicated by setting a
163        value in a variable in the "match data" data block.
164    
165    13. Be more explicit in pcre_study() instead of relying on "default" for
166        opcodes that mean there is no starting character; this means that when new
167        ones are added and accidentally left out of pcre_study(), testing should
168        pick them up.
169    
170    14. The -s option of pcretest has been documented for ages as being an old
171        synonym of -m (show memory usage). I have changed it to mean "force study
172        for every regex", that is, assume /S for every regex. This is similar to -i
173        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
174        using it. It makes it easier to run collections of tests with and without
175        study enabled, and thereby test pcre_study() more easily. All the standard
176        tests are now run with and without -s (but some patterns can be marked as
177        "never study" - see 20 below).
178    
179    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
180        restoration of the capturing data to the outer values was not happening
181        correctly.
182    
183    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
184        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
185        pattern had matched an empty string, and so incorrectly returned a no
186        match.
187    
188    17. There was optimizing code for the last branch of non-capturing parentheses,
189        and also for the obeyed branch of a conditional subexpression, which used
190        tail recursion to cut down on stack usage. Unfortunately, now that there is
191        the possibility of (*THEN) occurring in these branches, tail recursion is
192        no longer possible because the return has to be checked for (*THEN). These
193        two optimizations have therefore been removed. [But see 8.20/11 above.]
194    
195    18. If a pattern containing \R was studied, it was assumed that \R always
196        matched two bytes, thus causing the minimum subject length to be
197        incorrectly computed because \R can also match just one byte.
198    
199    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
200        was incorrectly computed.
201    
202    20. If /S is present twice on a test pattern in pcretest input, it now
203        *disables* studying, thereby overriding the use of -s on the command line
204        (see 14 above). This is necessary for one or two tests to keep the output
205        identical in both cases.
206    
207    21. When (*ACCEPT) was used in an assertion that matched an empty string and
208        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
209    
210    22. When an atomic group that contained a capturing parenthesis was
211        successfully matched, but the branch in which it appeared failed, the
212        capturing was not being forgotten if a higher numbered group was later
213        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
214        group 1 to "a", when in fact it should be unset. This applied to multi-
215        branched capturing and non-capturing groups, repeated or not, and also to
216        positive assertions (capturing in negative assertions does not happen
217        in PCRE) and also to nested atomic groups.
218    
219    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
220        subject after a captured substring, to make it easier to tell which of a
221        number of identical substrings has been captured.
222    
223    24. The way atomic groups are processed by pcre_exec() has been changed so that
224        if they are repeated, backtracking one repetition now resets captured
225        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
226        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
227        "aaa". Previously, it would have been "a". As part of this code
228        refactoring, the way recursive calls are handled has also been changed.
229    
230    25. If an assertion condition captured any substrings, they were not passed
231        back unless some other capturing happened later. For example, if
232        (?(?=(a))a) was matched against "a", no capturing was returned.
233    
234    26. When studying a pattern that contained subroutine calls or assertions,
235        the code for finding the minimum length of a possible match was handling
236        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
237        group 1 called group 2 while simultaneously a separate group 2 called group
238        1). A stack overflow occurred in this case. I have fixed this by limiting
239        the recursion depth to 10.
240    
241    27. Updated RunTest.bat in the distribution to the version supplied by Tom
242        Fortmann. This supports explicit test numbers on the command line, and has
243        argument validation and error reporting.
244    
245    28. An instance of \X with an unlimited repeat could fail if at any point the
246        first character it looked at was a mark character.
247    
248    29. Some minor code refactoring concerning Unicode properties and scripts
249        should reduce the stack requirement of match() slightly.
250    
251    30. Added the '=' option to pcretest to check the setting of unused capturing
252        slots at the end of the pattern, which are documented as being -1, but are
253        not included in the return count.
254    
255    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
256        compiled something random. Now it gives a compile-time error (as does
257        Perl).
258    
259    32. A *MARK encountered during the processing of a positive assertion is now
260        recorded and passed back (compatible with Perl).
261    
262    33. If --only-matching or --colour was set on a pcregrep call whose pattern
263        had alternative anchored branches, the search for a second match in a line
264        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
265        matched the line "0102" twice. The same bug affected patterns that started
266        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
267        twice.
268    
269    34. Previously, PCRE did not allow quantification of assertions. However, Perl
270        does, and because of capturing effects, quantifying parenthesized
271        assertions may at times be useful. Quantifiers are now allowed for
272        parenthesized assertions.
273    
274    35. A minor code tidy in pcre_compile() when checking options for \R usage.
275    
276    36. \g was being checked for fancy things in a character class, when it should
277        just be a literal "g".
278    
279    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
280        appearance of a nested POSIX class supersedes an apparent external class.
281        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
282        unescaped square brackets may also appear as part of class names. For
283        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
284        more like Perl. (But see 8.20/1 above.)
285    
286    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
287        was because it thought it was \N{name}, which is not supported).
288    
289    39. Add minix to OS list not supporting the -S option in pcretest.
290    
291    40. PCRE tries to detect cases of infinite recursion at compile time, but it
292        cannot analyze patterns in sufficient detail to catch mutual recursions
293        such as ((?1))((?2)). There is now a runtime test that gives an error if a
294        subgroup is called recursively as a subpattern for a second time at the
295        same position in the subject string. In previous releases this might have
296        been caught by the recursion limit, or it might have run out of stack.
297    
298    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
299        happen only once. PCRE was, however incorrectly giving a compile time error
300        "recursive call could loop indefinitely" because it cannot analyze the
301        pattern in sufficient detail. The compile time test no longer happens when
302        PCRE is compiling a conditional subpattern, but actual runaway loops are
303        now caught at runtime (see 40 above).
304    
305    42. It seems that Perl allows any characters other than a closing parenthesis
306        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
307        has been changed to be the same.
308    
309    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
310        as not to get warnings when autogen.sh is called. Also changed
311        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
312    
313    44. To help people who use pcregrep to scan files containing exceedingly long
314        lines, the following changes have been made:
315    
316        (a) The default value of the buffer size parameter has been increased from
317            8K to 20K. (The actual buffer used is three times this size.)
318    
319        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
320            PCRE is built.
321    
322        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
323            to be set at run time.
324    
325        (d) Numerical values in pcregrep options can be followed by K or M, for
326            example --buffer-size=50K.
327    
328        (e) If a line being scanned overflows pcregrep's buffer, an error is now
329            given and the return code is set to 2.
330    
331    45. Add a pointer to the latest mark to the callout data block.
332    
333    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
334        partial match of an empty string instead of no match. This was specific to
335        the use of ".".
336    
337    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
338        complete match instead of a partial match. This bug was dependent on both
339        the PCRE_UTF8 and PCRE_DOTALL options being set.
340    
341    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
342        starting byte set, because \b was not being ignored.
343    
344    
345    Version 8.12 15-Jan-2011
346  ------------------------  ------------------------
347    
348  1.  Fixed some typos in the markup of the man pages, and wrote a script that  1.  Fixed some typos in the markup of the man pages, and wrote a script that
349      checks for such things as part of the documentation building process.      checks for such things as part of the documentation building process.
350    
351  2.  On a big-endian 64-bit system, pcregrep did not correctly process the  2.  On a big-endian 64-bit system, pcregrep did not correctly process the
352      --match-limit and --recursion-limit options (added for 8.11). In      --match-limit and --recursion-limit options (added for 8.11). In
353      particular, this made one of the standard tests crash. (The integer value      particular, this made one of the standard tests fail. (The integer value
354      went into the wrong half of a long int.)      went into the wrong half of a long int.)
355    
356  3.  If the --colour option was given to pcregrep with -v (invert match), it  3.  If the --colour option was given to pcregrep with -v (invert match), it
357      did strange things, either producing crazy output, or crashing. It should,      did strange things, either producing crazy output, or crashing. It should,
358      of course, ignore a request for colour when reporting lines that do not      of course, ignore a request for colour when reporting lines that do not
359      match.      match.
360    
361  4.  Another pcregrep bug caused similar problems if --colour was specified with  4.  Another pcregrep bug caused similar problems if --colour was specified with
362      -M (multiline) and the pattern match finished with a line ending.      -M (multiline) and the pattern match finished with a line ending.
363    
364  5.  In pcregrep, when a pattern that ended with a literal newline sequence was  5.  In pcregrep, when a pattern that ended with a literal newline sequence was
365      matched in multiline mode, the following line was shown as part of the      matched in multiline mode, the following line was shown as part of the
366      match. This seems wrong, so I have changed it.      match. This seems wrong, so I have changed it.
367    
368  6.  If pcregrep was compiled under Windows, there was a reference to the  6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
369        the check for further matches in the same line (so they could be coloured)
370        to overrun the end of the current line. If another match was found, it was
371        incorrectly shown (and then shown again when found in the next line).
372    
373    7.  If pcregrep was compiled under Windows, there was a reference to the
374      function pcregrep_exit() before it was defined. I am assuming this was      function pcregrep_exit() before it was defined. I am assuming this was
375      the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was      the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
376      reported by a user. I've moved the definition above the reference.      reported by a user. I've moved the definition above the reference.
377    
378    
379  Version 8.11 10-Dec-2010  Version 8.11 10-Dec-2010
380  ------------------------  ------------------------

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