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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    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    
104    Version 8.13 16-Aug-2011
105    ------------------------
106    
107    1.  The Unicode data tables have been updated to Unicode 6.0.0.
108    
109    2.  Two minor typos in pcre_internal.h have been fixed.
110    
111    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
112        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
113        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
114    
115    4.  There were a number of related bugs in the code for matching backrefences
116        caselessly in UTF-8 mode when codes for the characters concerned were
117        different numbers of bytes. For example, U+023A and U+2C65 are an upper
118        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
119        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
120        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
121        2-byte code at the end of the subject (it thought there wasn't enough data
122        left).
123    
124    5.  Comprehensive information about what went wrong is now returned by
125        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
126        as the output vector has at least 2 elements. The offset of the start of
127        the failing character and a reason code are placed in the vector.
128    
129    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
130        now returned is for the first byte of the failing character, instead of the
131        last byte inspected. This is an incompatible change, but I hope it is small
132        enough not to be a problem. It makes the returned offset consistent with
133        pcre_exec() and pcre_dfa_exec().
134    
135    7.  pcretest now gives a text phrase as well as the error number when
136        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
137        failure, the offset and reason code are output.
138    
139    8.  When \R was used with a maximizing quantifier it failed to skip backwards
140        over a \r\n pair if the subsequent match failed. Instead, it just skipped
141        back over a single character (\n). This seems wrong (because it treated the
142        two characters as a single entity when going forwards), conflicts with the
143        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
144        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
145        has been changed.
146    
147    9.  Some internal refactoring has changed the processing so that the handling
148        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
149        time (the PCRE_DOTALL option was changed this way some time ago: version
150        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
151        which was always a bit of a fudge. It also means that there is one less
152        argument for the match() function, which reduces its stack requirements
153        slightly. This change also fixes an incompatibility with Perl: the pattern
154        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
155    
156    10. More internal refactoring has drastically reduced the number of recursive
157        calls to match() for possessively repeated groups such as (abc)++ when
158        using pcre_exec().
159    
160    11. While implementing 10, a number of bugs in the handling of groups were
161        discovered and fixed:
162    
163        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
164        (a|)*(?1) gave a compile-time internal error.
165        ((a|)+)+  did not notice that the outer group could match an empty string.
166        (^a|^)+   was not marked as anchored.
167        (.*a|.*)+ was not marked as matching at start or after a newline.
168    
169    12. Yet more internal refactoring has removed another argument from the match()
170        function. Special calls to this function are now indicated by setting a
171        value in a variable in the "match data" data block.
172    
173    13. Be more explicit in pcre_study() instead of relying on "default" for
174        opcodes that mean there is no starting character; this means that when new
175        ones are added and accidentally left out of pcre_study(), testing should
176        pick them up.
177    
178    14. The -s option of pcretest has been documented for ages as being an old
179        synonym of -m (show memory usage). I have changed it to mean "force study
180        for every regex", that is, assume /S for every regex. This is similar to -i
181        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
182        using it. It makes it easier to run collections of tests with and without
183        study enabled, and thereby test pcre_study() more easily. All the standard
184        tests are now run with and without -s (but some patterns can be marked as
185        "never study" - see 20 below).
186    
187    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
188        restoration of the capturing data to the outer values was not happening
189        correctly.
190    
191    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
192        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
193        pattern had matched an empty string, and so incorrectly returned a no
194        match.
195    
196    17. There was optimizing code for the last branch of non-capturing parentheses,
197        and also for the obeyed branch of a conditional subexpression, which used
198        tail recursion to cut down on stack usage. Unfortunately, now that there is
199        the possibility of (*THEN) occurring in these branches, tail recursion is
200        no longer possible because the return has to be checked for (*THEN). These
201        two optimizations have therefore been removed. [But see 8.20/11 above.]
202    
203    18. If a pattern containing \R was studied, it was assumed that \R always
204        matched two bytes, thus causing the minimum subject length to be
205        incorrectly computed because \R can also match just one byte.
206    
207    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
208        was incorrectly computed.
209    
210    20. If /S is present twice on a test pattern in pcretest input, it now
211        *disables* studying, thereby overriding the use of -s on the command line
212        (see 14 above). This is necessary for one or two tests to keep the output
213        identical in both cases.
214    
215    21. When (*ACCEPT) was used in an assertion that matched an empty string and
216        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
217    
218    22. When an atomic group that contained a capturing parenthesis was
219        successfully matched, but the branch in which it appeared failed, the
220        capturing was not being forgotten if a higher numbered group was later
221        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
222        group 1 to "a", when in fact it should be unset. This applied to multi-
223        branched capturing and non-capturing groups, repeated or not, and also to
224        positive assertions (capturing in negative assertions does not happen
225        in PCRE) and also to nested atomic groups.
226    
227    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
228        subject after a captured substring, to make it easier to tell which of a
229        number of identical substrings has been captured.
230    
231    24. The way atomic groups are processed by pcre_exec() has been changed so that
232        if they are repeated, backtracking one repetition now resets captured
233        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
234        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
235        "aaa". Previously, it would have been "a". As part of this code
236        refactoring, the way recursive calls are handled has also been changed.
237    
238    25. If an assertion condition captured any substrings, they were not passed
239        back unless some other capturing happened later. For example, if
240        (?(?=(a))a) was matched against "a", no capturing was returned.
241    
242    26. When studying a pattern that contained subroutine calls or assertions,
243        the code for finding the minimum length of a possible match was handling
244        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
245        group 1 called group 2 while simultaneously a separate group 2 called group
246        1). A stack overflow occurred in this case. I have fixed this by limiting
247        the recursion depth to 10.
248    
249    27. Updated RunTest.bat in the distribution to the version supplied by Tom
250        Fortmann. This supports explicit test numbers on the command line, and has
251        argument validation and error reporting.
252    
253    28. An instance of \X with an unlimited repeat could fail if at any point the
254        first character it looked at was a mark character.
255    
256    29. Some minor code refactoring concerning Unicode properties and scripts
257        should reduce the stack requirement of match() slightly.
258    
259    30. Added the '=' option to pcretest to check the setting of unused capturing
260        slots at the end of the pattern, which are documented as being -1, but are
261        not included in the return count.
262    
263    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
264        compiled something random. Now it gives a compile-time error (as does
265        Perl).
266    
267    32. A *MARK encountered during the processing of a positive assertion is now
268        recorded and passed back (compatible with Perl).
269    
270    33. If --only-matching or --colour was set on a pcregrep call whose pattern
271        had alternative anchored branches, the search for a second match in a line
272        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
273        matched the line "0102" twice. The same bug affected patterns that started
274        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
275        twice.
276    
277    34. Previously, PCRE did not allow quantification of assertions. However, Perl
278        does, and because of capturing effects, quantifying parenthesized
279        assertions may at times be useful. Quantifiers are now allowed for
280        parenthesized assertions.
281    
282    35. A minor code tidy in pcre_compile() when checking options for \R usage.
283    
284    36. \g was being checked for fancy things in a character class, when it should
285        just be a literal "g".
286    
287    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
288        appearance of a nested POSIX class supersedes an apparent external class.
289        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
290        unescaped square brackets may also appear as part of class names. For
291        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
292        more like Perl. (But see 8.20/1 above.)
293    
294    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
295        was because it thought it was \N{name}, which is not supported).
296    
297    39. Add minix to OS list not supporting the -S option in pcretest.
298    
299    40. PCRE tries to detect cases of infinite recursion at compile time, but it
300        cannot analyze patterns in sufficient detail to catch mutual recursions
301        such as ((?1))((?2)). There is now a runtime test that gives an error if a
302        subgroup is called recursively as a subpattern for a second time at the
303        same position in the subject string. In previous releases this might have
304        been caught by the recursion limit, or it might have run out of stack.
305    
306    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
307        happen only once. PCRE was, however incorrectly giving a compile time error
308        "recursive call could loop indefinitely" because it cannot analyze the
309        pattern in sufficient detail. The compile time test no longer happens when
310        PCRE is compiling a conditional subpattern, but actual runaway loops are
311        now caught at runtime (see 40 above).
312    
313    42. It seems that Perl allows any characters other than a closing parenthesis
314        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
315        has been changed to be the same.
316    
317    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
318        as not to get warnings when autogen.sh is called. Also changed
319        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
320    
321    44. To help people who use pcregrep to scan files containing exceedingly long
322        lines, the following changes have been made:
323    
324        (a) The default value of the buffer size parameter has been increased from
325            8K to 20K. (The actual buffer used is three times this size.)
326    
327        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
328            PCRE is built.
329    
330        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
331            to be set at run time.
332    
333        (d) Numerical values in pcregrep options can be followed by K or M, for
334            example --buffer-size=50K.
335    
336        (e) If a line being scanned overflows pcregrep's buffer, an error is now
337            given and the return code is set to 2.
338    
339    45. Add a pointer to the latest mark to the callout data block.
340    
341    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
342        partial match of an empty string instead of no match. This was specific to
343        the use of ".".
344    
345    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
346        complete match instead of a partial match. This bug was dependent on both
347        the PCRE_UTF8 and PCRE_DOTALL options being set.
348    
349    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
350        starting byte set, because \b was not being ignored.
351    
352    
353    Version 8.12 15-Jan-2011
354  ------------------------  ------------------------
355    
356  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
357      checks for such things as part of the documentation building process.      checks for such things as part of the documentation building process.
358    
359  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
360      --match-limit and --recursion-limit options (added for 8.11). In      --match-limit and --recursion-limit options (added for 8.11). In
361      particular, this made one of the standard tests crash. (The integer value      particular, this made one of the standard tests fail. (The integer value
362      went into the wrong half of a long int.)      went into the wrong half of a long int.)
363    
364    3.  If the --colour option was given to pcregrep with -v (invert match), it
365        did strange things, either producing crazy output, or crashing. It should,
366        of course, ignore a request for colour when reporting lines that do not
367        match.
368    
369    4.  Another pcregrep bug caused similar problems if --colour was specified with
370        -M (multiline) and the pattern match finished with a line ending.
371    
372    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
373        matched in multiline mode, the following line was shown as part of the
374        match. This seems wrong, so I have changed it.
375    
376    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
377        the check for further matches in the same line (so they could be coloured)
378        to overrun the end of the current line. If another match was found, it was
379        incorrectly shown (and then shown again when found in the next line).
380    
381    7.  If pcregrep was compiled under Windows, there was a reference to the
382        function pcregrep_exit() before it was defined. I am assuming this was
383        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
384        reported by a user. I've moved the definition above the reference.
385    
386    
387  Version 8.11 10-Dec-2010  Version 8.11 10-Dec-2010
388  ------------------------  ------------------------

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