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

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