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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
10       in a POSIX name.
11    
12    2. If a pattern such as /(a)b|ac/ is matched against "ac", there is no captured
13       substring, but while checking the failing first alternative, substring 1 is
14       temporarily captured. If the output vector supplied to pcre_exec() was not
15       big enough for this capture, the yield of the function was still zero
16       ("insufficient space for captured substrings"). This cannot be totally fixed
17       without adding another stack variable, which seems a lot of expense for a
18       edge case. However, I have improved the situation in cases such as
19       /(a)(b)x|abc/ matched against "abc", where the return code indicates that
20       fewer than the maximum number of slots in the ovector have been set.
21    
22    3. Related to (2) above: when there are more back references in a pattern than
23       slots in the output vector, pcre_exec() uses temporary memory during
24       matching, and copies in the captures as far as possible afterwards. It was
25       using the entire output vector, but this conflicts with the specification
26       that only 2/3 is used for passing back captured substrings. Now it uses only
27       the first 2/3, for compatibility. This is, of course, another edge case.
28    
29    4. Zoltan Herczeg's just-in-time compiler support has been integrated into the
30       main code base, and can be used by building with --enable-jit.
31    
32    
33    Version 8.13 16-Aug-2011
34    ------------------------
35    
36    1.  The Unicode data tables have been updated to Unicode 6.0.0.
37    
38    2.  Two minor typos in pcre_internal.h have been fixed.
39    
40    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
41        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
42        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
43    
44    4.  There were a number of related bugs in the code for matching backrefences
45        caselessly in UTF-8 mode when codes for the characters concerned were
46        different numbers of bytes. For example, U+023A and U+2C65 are an upper
47        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
48        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
49        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
50        2-byte code at the end of the subject (it thought there wasn't enough data
51        left).
52    
53    5.  Comprehensive information about what went wrong is now returned by
54        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
55        as the output vector has at least 2 elements. The offset of the start of
56        the failing character and a reason code are placed in the vector.
57    
58    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
59        now returned is for the first byte of the failing character, instead of the
60        last byte inspected. This is an incompatible change, but I hope it is small
61        enough not to be a problem. It makes the returned offset consistent with
62        pcre_exec() and pcre_dfa_exec().
63    
64    7.  pcretest now gives a text phrase as well as the error number when
65        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
66        failure, the offset and reason code are output.
67    
68    8.  When \R was used with a maximizing quantifier it failed to skip backwards
69        over a \r\n pair if the subsequent match failed. Instead, it just skipped
70        back over a single character (\n). This seems wrong (because it treated the
71        two characters as a single entity when going forwards), conflicts with the
72        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
73        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
74        has been changed.
75    
76    9.  Some internal refactoring has changed the processing so that the handling
77        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
78        time (the PCRE_DOTALL option was changed this way some time ago: version
79        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
80        which was always a bit of a fudge. It also means that there is one less
81        argument for the match() function, which reduces its stack requirements
82        slightly. This change also fixes an incompatibility with Perl: the pattern
83        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
84    
85    10. More internal refactoring has drastically reduced the number of recursive
86        calls to match() for possessively repeated groups such as (abc)++ when
87        using pcre_exec().
88    
89    11. While implementing 10, a number of bugs in the handling of groups were
90        discovered and fixed:
91    
92        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
93        (a|)*(?1) gave a compile-time internal error.
94        ((a|)+)+  did not notice that the outer group could match an empty string.
95        (^a|^)+   was not marked as anchored.
96        (.*a|.*)+ was not marked as matching at start or after a newline.
97    
98    12. Yet more internal refactoring has removed another argument from the match()
99        function. Special calls to this function are now indicated by setting a
100        value in a variable in the "match data" data block.
101    
102    13. Be more explicit in pcre_study() instead of relying on "default" for
103        opcodes that mean there is no starting character; this means that when new
104        ones are added and accidentally left out of pcre_study(), testing should
105        pick them up.
106    
107    14. The -s option of pcretest has been documented for ages as being an old
108        synonym of -m (show memory usage). I have changed it to mean "force study
109        for every regex", that is, assume /S for every regex. This is similar to -i
110        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
111        using it. It makes it easier to run collections of tests with and without
112        study enabled, and thereby test pcre_study() more easily. All the standard
113        tests are now run with and without -s (but some patterns can be marked as
114        "never study" - see 20 below).
115    
116    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
117        restoration of the capturing data to the outer values was not happening
118        correctly.
119    
120    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
121        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
122        pattern had matched an empty string, and so incorrectly returned a no
123        match.
124    
125    17. There was optimizing code for the last branch of non-capturing parentheses,
126        and also for the obeyed branch of a conditional subexpression, which used
127        tail recursion to cut down on stack usage. Unfortunately, now that there is
128        the possibility of (*THEN) occurring in these branches, tail recursion is
129        no longer possible because the return has to be checked for (*THEN). These
130        two optimizations have therefore been removed.
131    
132    18. If a pattern containing \R was studied, it was assumed that \R always
133        matched two bytes, thus causing the minimum subject length to be
134        incorrectly computed because \R can also match just one byte.
135    
136    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
137        was incorrectly computed.
138    
139    20. If /S is present twice on a test pattern in pcretest input, it now
140        *disables* studying, thereby overriding the use of -s on the command line
141        (see 14 above). This is necessary for one or two tests to keep the output
142        identical in both cases.
143    
144    21. When (*ACCEPT) was used in an assertion that matched an empty string and
145        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
146    
147    22. When an atomic group that contained a capturing parenthesis was
148        successfully matched, but the branch in which it appeared failed, the
149        capturing was not being forgotten if a higher numbered group was later
150        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
151        group 1 to "a", when in fact it should be unset. This applied to multi-
152        branched capturing and non-capturing groups, repeated or not, and also to
153        positive assertions (capturing in negative assertions does not happen
154        in PCRE) and also to nested atomic groups.
155    
156    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
157        subject after a captured substring, to make it easier to tell which of a
158        number of identical substrings has been captured.
159    
160    24. The way atomic groups are processed by pcre_exec() has been changed so that
161        if they are repeated, backtracking one repetition now resets captured
162        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
163        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
164        "aaa". Previously, it would have been "a". As part of this code
165        refactoring, the way recursive calls are handled has also been changed.
166    
167    25. If an assertion condition captured any substrings, they were not passed
168        back unless some other capturing happened later. For example, if
169        (?(?=(a))a) was matched against "a", no capturing was returned.
170    
171    26. When studying a pattern that contained subroutine calls or assertions,
172        the code for finding the minimum length of a possible match was handling
173        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
174        group 1 called group 2 while simultaneously a separate group 2 called group
175        1). A stack overflow occurred in this case. I have fixed this by limiting
176        the recursion depth to 10.
177    
178    27. Updated RunTest.bat in the distribution to the version supplied by Tom
179        Fortmann. This supports explicit test numbers on the command line, and has
180        argument validation and error reporting.
181    
182    28. An instance of \X with an unlimited repeat could fail if at any point the
183        first character it looked at was a mark character.
184    
185    29. Some minor code refactoring concerning Unicode properties and scripts
186        should reduce the stack requirement of match() slightly.
187    
188    30. Added the '=' option to pcretest to check the setting of unused capturing
189        slots at the end of the pattern, which are documented as being -1, but are
190        not included in the return count.
191    
192    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
193        compiled something random. Now it gives a compile-time error (as does
194        Perl).
195    
196    32. A *MARK encountered during the processing of a positive assertion is now
197        recorded and passed back (compatible with Perl).
198    
199    33. If --only-matching or --colour was set on a pcregrep call whose pattern
200        had alternative anchored branches, the search for a second match in a line
201        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
202        matched the line "0102" twice. The same bug affected patterns that started
203        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
204        twice.
205    
206    34. Previously, PCRE did not allow quantification of assertions. However, Perl
207        does, and because of capturing effects, quantifying parenthesized
208        assertions may at times be useful. Quantifiers are now allowed for
209        parenthesized assertions.
210    
211    35. A minor code tidy in pcre_compile() when checking options for \R usage.
212    
213    36. \g was being checked for fancy things in a character class, when it should
214        just be a literal "g".
215    
216    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
217        appearance of a nested POSIX class supersedes an apparent external class.
218        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
219        unescaped square brackets may also appear as part of class names. For
220        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
221        more like Perl. (But see 8.20/1 above.)
222    
223    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
224        was because it thought it was \N{name}, which is not supported).
225    
226    39. Add minix to OS list not supporting the -S option in pcretest.
227    
228    40. PCRE tries to detect cases of infinite recursion at compile time, but it
229        cannot analyze patterns in sufficient detail to catch mutual recursions
230        such as ((?1))((?2)). There is now a runtime test that gives an error if a
231        subgroup is called recursively as a subpattern for a second time at the
232        same position in the subject string. In previous releases this might have
233        been caught by the recursion limit, or it might have run out of stack.
234    
235    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
236        happen only once. PCRE was, however incorrectly giving a compile time error
237        "recursive call could loop indefinitely" because it cannot analyze the
238        pattern in sufficient detail. The compile time test no longer happens when
239        PCRE is compiling a conditional subpattern, but actual runaway loops are
240        now caught at runtime (see 40 above).
241    
242    42. It seems that Perl allows any characters other than a closing parenthesis
243        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
244        has been changed to be the same.
245    
246    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
247        as not to get warnings when autogen.sh is called. Also changed
248        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
249    
250    44. To help people who use pcregrep to scan files containing exceedingly long
251        lines, the following changes have been made:
252    
253        (a) The default value of the buffer size parameter has been increased from
254            8K to 20K. (The actual buffer used is three times this size.)
255    
256        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
257            PCRE is built.
258    
259        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
260            to be set at run time.
261    
262        (d) Numerical values in pcregrep options can be followed by K or M, for
263            example --buffer-size=50K.
264    
265        (e) If a line being scanned overflows pcregrep's buffer, an error is now
266            given and the return code is set to 2.
267    
268    45. Add a pointer to the latest mark to the callout data block.
269    
270    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
271        partial match of an empty string instead of no match. This was specific to
272        the use of ".".
273    
274    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
275        complete match instead of a partial match. This bug was dependent on both
276        the PCRE_UTF8 and PCRE_DOTALL options being set.
277    
278    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
279        starting byte set, because \b was not being ignored.
280    
281    
282    Version 8.12 15-Jan-2011
283    ------------------------
284    
285    1.  Fixed some typos in the markup of the man pages, and wrote a script that
286        checks for such things as part of the documentation building process.
287    
288    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
289        --match-limit and --recursion-limit options (added for 8.11). In
290        particular, this made one of the standard tests fail. (The integer value
291        went into the wrong half of a long int.)
292    
293    3.  If the --colour option was given to pcregrep with -v (invert match), it
294        did strange things, either producing crazy output, or crashing. It should,
295        of course, ignore a request for colour when reporting lines that do not
296        match.
297    
298    4.  Another pcregrep bug caused similar problems if --colour was specified with
299        -M (multiline) and the pattern match finished with a line ending.
300    
301    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
302        matched in multiline mode, the following line was shown as part of the
303        match. This seems wrong, so I have changed it.
304    
305    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
306        the check for further matches in the same line (so they could be coloured)
307        to overrun the end of the current line. If another match was found, it was
308        incorrectly shown (and then shown again when found in the next line).
309    
310    7.  If pcregrep was compiled under Windows, there was a reference to the
311        function pcregrep_exit() before it was defined. I am assuming this was
312        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
313        reported by a user. I've moved the definition above the reference.
314    
315    
316    Version 8.11 10-Dec-2010
317  ------------------------  ------------------------
318    
319  1.  (*THEN) was not working properly if there were untried alternatives prior  1.  (*THEN) was not working properly if there were untried alternatives prior
320      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
321      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
322      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
323      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
324      alternative in the innermost enclosing group".      alternative in the innermost enclosing group".
325    
326  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
327      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
328      result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and      result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
329      (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides      (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
330      (*THEN).      (*THEN).
331    
332  3.  If \s appeared in a character class, it removed the VT character from  3.  If \s appeared in a character class, it removed the VT character from
333      the class, even if it had been included by some previous item, for example      the class, even if it had been included by some previous item, for example
334      in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part      in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
335      of \s, but is part of the POSIX "space" class.)      of \s, but is part of the POSIX "space" class.)
336    
337  4.  A partial match never returns an empty string (because you can always  4.  A partial match never returns an empty string (because you can always
338      match an empty string at the end of the subject); however the checking for      match an empty string at the end of the subject); however the checking for
339      an empty string was starting at the "start of match" point. This has been      an empty string was starting at the "start of match" point. This has been
# Line 31  Version 8.11 10-Oct-2010 Line 343  Version 8.11 10-Oct-2010
343      (previously it gave "no match").      (previously it gave "no match").
344    
345  5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching  5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
346      of $, \z, \Z, \b, and \B. If the match point is at the end of the string,      of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
347      previously a full match would be given. However, setting PCRE_PARTIAL_HARD      previously a full match would be given. However, setting PCRE_PARTIAL_HARD
348      has an implication that the given string is incomplete (because a partial      has an implication that the given string is incomplete (because a partial
349      match is preferred over a full match). For this reason, these items now      match is preferred over a full match). For this reason, these items now
350      give a partial match in this situation. [Aside: previously, the one case      give a partial match in this situation. [Aside: previously, the one case
351      /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial      /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
352      match rather than a full match, which was wrong by the old rules, but is      match rather than a full match, which was wrong by the old rules, but is
353      now correct.]      now correct.]
354    
355    6.  There was a bug in the handling of #-introduced comments, recognized when
356        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
357        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
358        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
359        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
360        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
361        places in pcre_compile().
362    
363    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
364        comments when looking ahead for named forward references to subpatterns,
365        the only newline sequence it recognized was NL. It now handles newlines
366        according to the set newline convention.
367    
368    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
369        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
370        cater for a lack of strerror(). These oversights have been fixed.
371    
372    9.  Added --match-limit and --recursion-limit to pcregrep.
373    
374    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
375    
376    11. When the -o option was used, pcregrep was setting a return code of 1, even
377        when matches were found, and --line-buffered was not being honoured.
378    
379    12. Added an optional parentheses number to the -o and --only-matching options
380        of pcregrep.
381    
382    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
383        can match an empty string. The code to do it in pcretest and pcredemo
384        needed fixing:
385    
386        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
387            only one byte after an empty string match just before CRLF (this case
388            just got forgotten; "any" and "anycrlf" were OK).
389    
390        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
391            mode when an empty string match preceded an ASCII character followed by
392            a non-ASCII character. (The code for advancing by one character rather
393            than one byte was nonsense.)
394    
395        (c) The pcredemo.c sample program did not have any code at all to handle
396            the cases when CRLF is a valid newline sequence.
397    
398    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
399        as a starting offset was within the subject string. There is now a new
400        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
401        negative or greater than the length of the string. In order to test this,
402        pcretest is extended to allow the setting of negative starting offsets.
403    
404    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
405        starting offset points to the beginning of a UTF-8 character was
406        unnecessarily clumsy. I tidied it up.
407    
408    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
409        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
410    
411    17. Nobody had reported that the --include_dir option, which was added in
412        release 7.7 should have been called --include-dir (hyphen, not underscore)
413        for compatibility with GNU grep. I have changed it to --include-dir, but
414        left --include_dir as an undocumented synonym, and the same for
415        --exclude-dir, though that is not available in GNU grep, at least as of
416        release 2.5.4.
417    
418    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
419        characters from a string of bytes) have been redefined so as not to use
420        loops, in order to improve performance in some environments. At the same
421        time, I abstracted some of the common code into auxiliary macros to save
422        repetition (this should not affect the compiled code).
423    
424    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
425        compile-time error is now given if \c is not followed by an ASCII
426        character, that is, a byte less than 128. (In EBCDIC mode, the code is
427        different, and any byte value is allowed.)
428    
429    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
430        START_OPTIMIZE option, which is now allowed at compile time - but just
431        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
432        to pcregrep and other applications that have no direct access to PCRE
433        options. The new /Y option in pcretest sets this option when calling
434        pcre_compile().
435    
436    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
437        back references. Groups containing recursive back references were forced to
438        be atomic by that change, but in the case of named groups, the amount of
439        memory required was incorrectly computed, leading to "Failed: internal
440        error: code overflow". This has been fixed.
441    
442    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
443        pcretest.c, to avoid build problems in some Borland environments.
444    
445    
446  Version 8.10 25-Jun-2010  Version 8.10 25-Jun-2010

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