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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.11 10-Oct-2010  Version 8.20
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 in
10    a POSIX name.
11    
12    
13    Version 8.13 16-Aug-2011
14    ------------------------
15    
16    1.  The Unicode data tables have been updated to Unicode 6.0.0.
17    
18    2.  Two minor typos in pcre_internal.h have been fixed.
19    
20    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
21        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
22        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
23    
24    4.  There were a number of related bugs in the code for matching backrefences
25        caselessly in UTF-8 mode when codes for the characters concerned were
26        different numbers of bytes. For example, U+023A and U+2C65 are an upper
27        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
28        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
29        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
30        2-byte code at the end of the subject (it thought there wasn't enough data
31        left).
32    
33    5.  Comprehensive information about what went wrong is now returned by
34        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
35        as the output vector has at least 2 elements. The offset of the start of
36        the failing character and a reason code are placed in the vector.
37    
38    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
39        now returned is for the first byte of the failing character, instead of the
40        last byte inspected. This is an incompatible change, but I hope it is small
41        enough not to be a problem. It makes the returned offset consistent with
42        pcre_exec() and pcre_dfa_exec().
43    
44    7.  pcretest now gives a text phrase as well as the error number when
45        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
46        failure, the offset and reason code are output.
47    
48    8.  When \R was used with a maximizing quantifier it failed to skip backwards
49        over a \r\n pair if the subsequent match failed. Instead, it just skipped
50        back over a single character (\n). This seems wrong (because it treated the
51        two characters as a single entity when going forwards), conflicts with the
52        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
53        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
54        has been changed.
55    
56    9.  Some internal refactoring has changed the processing so that the handling
57        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
58        time (the PCRE_DOTALL option was changed this way some time ago: version
59        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
60        which was always a bit of a fudge. It also means that there is one less
61        argument for the match() function, which reduces its stack requirements
62        slightly. This change also fixes an incompatibility with Perl: the pattern
63        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
64    
65    10. More internal refactoring has drastically reduced the number of recursive
66        calls to match() for possessively repeated groups such as (abc)++ when
67        using pcre_exec().
68    
69    11. While implementing 10, a number of bugs in the handling of groups were
70        discovered and fixed:
71    
72        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
73        (a|)*(?1) gave a compile-time internal error.
74        ((a|)+)+  did not notice that the outer group could match an empty string.
75        (^a|^)+   was not marked as anchored.
76        (.*a|.*)+ was not marked as matching at start or after a newline.
77    
78    12. Yet more internal refactoring has removed another argument from the match()
79        function. Special calls to this function are now indicated by setting a
80        value in a variable in the "match data" data block.
81    
82    13. Be more explicit in pcre_study() instead of relying on "default" for
83        opcodes that mean there is no starting character; this means that when new
84        ones are added and accidentally left out of pcre_study(), testing should
85        pick them up.
86    
87    14. The -s option of pcretest has been documented for ages as being an old
88        synonym of -m (show memory usage). I have changed it to mean "force study
89        for every regex", that is, assume /S for every regex. This is similar to -i
90        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
91        using it. It makes it easier to run collections of tests with and without
92        study enabled, and thereby test pcre_study() more easily. All the standard
93        tests are now run with and without -s (but some patterns can be marked as
94        "never study" - see 20 below).
95    
96    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
97        restoration of the capturing data to the outer values was not happening
98        correctly.
99    
100    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
101        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
102        pattern had matched an empty string, and so incorrectly returned a no
103        match.
104    
105    17. There was optimizing code for the last branch of non-capturing parentheses,
106        and also for the obeyed branch of a conditional subexpression, which used
107        tail recursion to cut down on stack usage. Unfortunately, now that there is
108        the possibility of (*THEN) occurring in these branches, tail recursion is
109        no longer possible because the return has to be checked for (*THEN). These
110        two optimizations have therefore been removed.
111    
112    18. If a pattern containing \R was studied, it was assumed that \R always
113        matched two bytes, thus causing the minimum subject length to be
114        incorrectly computed because \R can also match just one byte.
115    
116    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
117        was incorrectly computed.
118    
119    20. If /S is present twice on a test pattern in pcretest input, it now
120        *disables* studying, thereby overriding the use of -s on the command line
121        (see 14 above). This is necessary for one or two tests to keep the output
122        identical in both cases.
123    
124    21. When (*ACCEPT) was used in an assertion that matched an empty string and
125        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
126    
127    22. When an atomic group that contained a capturing parenthesis was
128        successfully matched, but the branch in which it appeared failed, the
129        capturing was not being forgotten if a higher numbered group was later
130        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
131        group 1 to "a", when in fact it should be unset. This applied to multi-
132        branched capturing and non-capturing groups, repeated or not, and also to
133        positive assertions (capturing in negative assertions does not happen
134        in PCRE) and also to nested atomic groups.
135    
136    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
137        subject after a captured substring, to make it easier to tell which of a
138        number of identical substrings has been captured.
139    
140    24. The way atomic groups are processed by pcre_exec() has been changed so that
141        if they are repeated, backtracking one repetition now resets captured
142        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
143        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
144        "aaa". Previously, it would have been "a". As part of this code
145        refactoring, the way recursive calls are handled has also been changed.
146    
147    25. If an assertion condition captured any substrings, they were not passed
148        back unless some other capturing happened later. For example, if
149        (?(?=(a))a) was matched against "a", no capturing was returned.
150    
151    26. When studying a pattern that contained subroutine calls or assertions,
152        the code for finding the minimum length of a possible match was handling
153        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
154        group 1 called group 2 while simultaneously a separate group 2 called group
155        1). A stack overflow occurred in this case. I have fixed this by limiting
156        the recursion depth to 10.
157    
158    27. Updated RunTest.bat in the distribution to the version supplied by Tom
159        Fortmann. This supports explicit test numbers on the command line, and has
160        argument validation and error reporting.
161    
162    28. An instance of \X with an unlimited repeat could fail if at any point the
163        first character it looked at was a mark character.
164    
165    29. Some minor code refactoring concerning Unicode properties and scripts
166        should reduce the stack requirement of match() slightly.
167    
168    30. Added the '=' option to pcretest to check the setting of unused capturing
169        slots at the end of the pattern, which are documented as being -1, but are
170        not included in the return count.
171    
172    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
173        compiled something random. Now it gives a compile-time error (as does
174        Perl).
175    
176    32. A *MARK encountered during the processing of a positive assertion is now
177        recorded and passed back (compatible with Perl).
178    
179    33. If --only-matching or --colour was set on a pcregrep call whose pattern
180        had alternative anchored branches, the search for a second match in a line
181        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
182        matched the line "0102" twice. The same bug affected patterns that started
183        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
184        twice.
185    
186    34. Previously, PCRE did not allow quantification of assertions. However, Perl
187        does, and because of capturing effects, quantifying parenthesized
188        assertions may at times be useful. Quantifiers are now allowed for
189        parenthesized assertions.
190    
191    35. A minor code tidy in pcre_compile() when checking options for \R usage.
192    
193    36. \g was being checked for fancy things in a character class, when it should
194        just be a literal "g".
195    
196    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
197        appearance of a nested POSIX class supersedes an apparent external class.
198        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
199        unescaped square brackets may also appear as part of class names. For
200        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
201        more like Perl. (But see 8.20/1 above.)
202    
203    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
204        was because it thought it was \N{name}, which is not supported).
205    
206    39. Add minix to OS list not supporting the -S option in pcretest.
207    
208    40. PCRE tries to detect cases of infinite recursion at compile time, but it
209        cannot analyze patterns in sufficient detail to catch mutual recursions
210        such as ((?1))((?2)). There is now a runtime test that gives an error if a
211        subgroup is called recursively as a subpattern for a second time at the
212        same position in the subject string. In previous releases this might have
213        been caught by the recursion limit, or it might have run out of stack.
214    
215    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
216        happen only once. PCRE was, however incorrectly giving a compile time error
217        "recursive call could loop indefinitely" because it cannot analyze the
218        pattern in sufficient detail. The compile time test no longer happens when
219        PCRE is compiling a conditional subpattern, but actual runaway loops are
220        now caught at runtime (see 40 above).
221    
222    42. It seems that Perl allows any characters other than a closing parenthesis
223        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
224        has been changed to be the same.
225    
226    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
227        as not to get warnings when autogen.sh is called. Also changed
228        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
229    
230    44. To help people who use pcregrep to scan files containing exceedingly long
231        lines, the following changes have been made:
232    
233        (a) The default value of the buffer size parameter has been increased from
234            8K to 20K. (The actual buffer used is three times this size.)
235    
236        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
237            PCRE is built.
238    
239        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
240            to be set at run time.
241    
242        (d) Numerical values in pcregrep options can be followed by K or M, for
243            example --buffer-size=50K.
244    
245        (e) If a line being scanned overflows pcregrep's buffer, an error is now
246            given and the return code is set to 2.
247    
248    45. Add a pointer to the latest mark to the callout data block.
249    
250    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
251        partial match of an empty string instead of no match. This was specific to
252        the use of ".".
253    
254    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
255        complete match instead of a partial match. This bug was dependent on both
256        the PCRE_UTF8 and PCRE_DOTALL options being set.
257    
258    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
259        starting byte set, because \b was not being ignored.
260    
261    
262    Version 8.12 15-Jan-2011
263    ------------------------
264    
265    1.  Fixed some typos in the markup of the man pages, and wrote a script that
266        checks for such things as part of the documentation building process.
267    
268    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
269        --match-limit and --recursion-limit options (added for 8.11). In
270        particular, this made one of the standard tests fail. (The integer value
271        went into the wrong half of a long int.)
272    
273    3.  If the --colour option was given to pcregrep with -v (invert match), it
274        did strange things, either producing crazy output, or crashing. It should,
275        of course, ignore a request for colour when reporting lines that do not
276        match.
277    
278    4.  Another pcregrep bug caused similar problems if --colour was specified with
279        -M (multiline) and the pattern match finished with a line ending.
280    
281    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
282        matched in multiline mode, the following line was shown as part of the
283        match. This seems wrong, so I have changed it.
284    
285    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
286        the check for further matches in the same line (so they could be coloured)
287        to overrun the end of the current line. If another match was found, it was
288        incorrectly shown (and then shown again when found in the next line).
289    
290    7.  If pcregrep was compiled under Windows, there was a reference to the
291        function pcregrep_exit() before it was defined. I am assuming this was
292        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
293        reported by a user. I've moved the definition above the reference.
294    
295    
296    Version 8.11 10-Dec-2010
297  ------------------------  ------------------------
298    
299  1.  (*THEN) was not working properly if there were untried alternatives prior  1.  (*THEN) was not working properly if there were untried alternatives prior
300      to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it      to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
301      backtracked to try for "b" instead of moving to the next alternative branch      backtracked to try for "b" instead of moving to the next alternative branch
302      at the same level (in this case, to look for "c"). The Perl documentation      at the same level (in this case, to look for "c"). The Perl documentation
303      is clear that when (*THEN) is backtracked onto, it goes to the "next      is clear that when (*THEN) is backtracked onto, it goes to the "next
304      alternative in the innermost enclosing group".      alternative in the innermost enclosing group".
305    
306  2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern  2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
307      such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should      such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
308      result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and      result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
309      (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides      (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
310      (*THEN).      (*THEN).
311    
312    3.  If \s appeared in a character class, it removed the VT character from
313        the class, even if it had been included by some previous item, for example
314        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
315        of \s, but is part of the POSIX "space" class.)
316    
317    4.  A partial match never returns an empty string (because you can always
318        match an empty string at the end of the subject); however the checking for
319        an empty string was starting at the "start of match" point. This has been
320        changed to the "earliest inspected character" point, because the returned
321        data for a partial match starts at this character. This means that, for
322        example, /(?<=abc)def/ gives a partial match for the subject "abc"
323        (previously it gave "no match").
324    
325    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
326        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
327        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
328        has an implication that the given string is incomplete (because a partial
329        match is preferred over a full match). For this reason, these items now
330        give a partial match in this situation. [Aside: previously, the one case
331        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
332        match rather than a full match, which was wrong by the old rules, but is
333        now correct.]
334    
335    6.  There was a bug in the handling of #-introduced comments, recognized when
336        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
337        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
338        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
339        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
340        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
341        places in pcre_compile().
342    
343    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
344        comments when looking ahead for named forward references to subpatterns,
345        the only newline sequence it recognized was NL. It now handles newlines
346        according to the set newline convention.
347    
348    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
349        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
350        cater for a lack of strerror(). These oversights have been fixed.
351    
352    9.  Added --match-limit and --recursion-limit to pcregrep.
353    
354    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
355    
356    11. When the -o option was used, pcregrep was setting a return code of 1, even
357        when matches were found, and --line-buffered was not being honoured.
358    
359    12. Added an optional parentheses number to the -o and --only-matching options
360        of pcregrep.
361    
362    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
363        can match an empty string. The code to do it in pcretest and pcredemo
364        needed fixing:
365    
366        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
367            only one byte after an empty string match just before CRLF (this case
368            just got forgotten; "any" and "anycrlf" were OK).
369    
370        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
371            mode when an empty string match preceded an ASCII character followed by
372            a non-ASCII character. (The code for advancing by one character rather
373            than one byte was nonsense.)
374    
375        (c) The pcredemo.c sample program did not have any code at all to handle
376            the cases when CRLF is a valid newline sequence.
377    
378    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
379        as a starting offset was within the subject string. There is now a new
380        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
381        negative or greater than the length of the string. In order to test this,
382        pcretest is extended to allow the setting of negative starting offsets.
383    
384    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
385        starting offset points to the beginning of a UTF-8 character was
386        unnecessarily clumsy. I tidied it up.
387    
388    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
389        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
390    
391    17. Nobody had reported that the --include_dir option, which was added in
392        release 7.7 should have been called --include-dir (hyphen, not underscore)
393        for compatibility with GNU grep. I have changed it to --include-dir, but
394        left --include_dir as an undocumented synonym, and the same for
395        --exclude-dir, though that is not available in GNU grep, at least as of
396        release 2.5.4.
397    
398    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
399        characters from a string of bytes) have been redefined so as not to use
400        loops, in order to improve performance in some environments. At the same
401        time, I abstracted some of the common code into auxiliary macros to save
402        repetition (this should not affect the compiled code).
403    
404    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
405        compile-time error is now given if \c is not followed by an ASCII
406        character, that is, a byte less than 128. (In EBCDIC mode, the code is
407        different, and any byte value is allowed.)
408    
409    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
410        START_OPTIMIZE option, which is now allowed at compile time - but just
411        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
412        to pcregrep and other applications that have no direct access to PCRE
413        options. The new /Y option in pcretest sets this option when calling
414        pcre_compile().
415    
416    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
417        back references. Groups containing recursive back references were forced to
418        be atomic by that change, but in the case of named groups, the amount of
419        memory required was incorrectly computed, leading to "Failed: internal
420        error: code overflow". This has been fixed.
421    
422    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
423        pcretest.c, to avoid build problems in some Borland environments.
424    
425    
426  Version 8.10 25-Jun-2010  Version 8.10 25-Jun-2010

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