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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.00 ??-???-??  Version 8.21 05-Dec-2011
5    ------------------------
6    
7    1.  Updating the JIT compiler.
8    
9    2.  JIT compiler now supports OP_NCREF, OP_RREF and OP_NRREF. New test cases
10        are added as well.
11    
12    3.  Fix cache-flush issue on PowerPC (It is still an experimental JIT port).
13        PCRE_EXTRA_TABLES is not suported by JIT, and should be checked before
14        calling _pcre_jit_exec. Some extra comments are added.
15    
16    4.  (*MARK) settings inside atomic groups that do not contain any capturing
17        parentheses, for example, (?>a(*:m)), were not being passed out. This bug
18        was introduced by change 18 for 8.20.
19    
20    5.  Supporting of \x, \U and \u in JavaScript compatibility mode based on the
21        ECMA-262 standard.
22    
23    6.  Lookbehinds such as (?<=a{2}b) that contained a fixed repetition were
24        erroneously being rejected as "not fixed length" if PCRE_CASELESS was set.
25        This bug was probably introduced by change 9 of 8.13.
26    
27    7.  While fixing 6 above, I noticed that a number of other items were being
28        incorrectly rejected as "not fixed length". This arose partly because newer
29        opcodes had not been added to the fixed-length checking code. I have (a)
30        corrected the bug and added tests for these items, and (b) arranged for an
31        error to occur if an unknown opcode is encountered while checking for fixed
32        length instead of just assuming "not fixed length". The items that were
33        rejected were: (*ACCEPT), (*COMMIT), (*FAIL), (*MARK), (*PRUNE), (*SKIP),
34        (*THEN), \h, \H, \v, \V, and single character negative classes with fixed
35        repetitions, e.g. [^a]{3}, with and without PCRE_CASELESS.
36    
37    8.  A possessively repeated conditional subpattern such as (?(?=c)c|d)++ was
38        being incorrectly compiled and would have given unpredicatble results.
39    
40    9.  A possessively repeated subpattern with minimum repeat count greater than
41        one behaved incorrectly. For example, (A){2,}+ behaved as if it was
42        (A)(A)++ which meant that, after a subsequent mismatch, backtracking into
43        the first (A) could occur when it should not.
44    
45    10. Add a cast and remove a redundant test from the code.
46    
47    11. JIT should use pcre_malloc/pcre_free for allocation.
48    
49    12. Updated pcre-config so that it no longer shows -L/usr/lib, which seems
50        best practice nowadays, and helps with cross-compiling. (If the exec_prefix
51        is anything other than /usr, -L is still shown).
52    
53    13. In non-UTF-8 mode, \C is now supported in lookbehinds and DFA matching.
54    
55    14. Perl does not support \N without a following name in a [] class; PCRE now
56        also gives an error.
57    
58    15. If a forward reference was repeated with an upper limit of around 2000,
59        it caused the error "internal error: overran compiling workspace". The
60        maximum number of forward references (including repeats) was limited by the
61        internal workspace, and dependent on the LINK_SIZE. The code has been
62        rewritten so that the workspace expands (via pcre_malloc) if necessary, and
63        the default depends on LINK_SIZE. There is a new upper limit (for safety)
64        of around 200,000 forward references. While doing this, I also speeded up
65        the filling in of repeated forward references.
66    
67    16. A repeated forward reference in a pattern such as (a)(?2){2}(.) was
68        incorrectly expecting the subject to contain another "a" after the start.
69    
70    17. When (*SKIP:name) is activated without a corresponding (*MARK:name) earlier
71        in the match, the SKIP should be ignored. This was not happening; instead
72        the SKIP was being treated as NOMATCH. For patterns such as
73        /A(*MARK:A)A+(*SKIP:B)Z|AAC/ this meant that the AAC branch was never
74        tested.
75    
76    18. The behaviour of (*MARK), (*PRUNE), and (*THEN) has been reworked and is
77        now much more compatible with Perl, in particular in cases where the result
78        is a non-match for a non-anchored pattern. For example, if
79        /b(*:m)f|a(*:n)w/ is matched against "abc", the non-match returns the name
80        "m", where previously it did not return a name. A side effect of this
81        change is that for partial matches, the last encountered mark name is
82        returned, as for non matches. A number of tests that were previously not
83        Perl-compatible have been moved into the Perl-compatible test files. The
84        refactoring has had the pleasing side effect of removing one argument from
85        the match() function, thus reducing its stack requirements.
86    
87    19. If the /S+ option was used in pcretest to study a pattern using JIT,
88        subsequent uses of /S (without +) incorrectly behaved like /S+.
89    
90    21. Retrieve executable code size support for the JIT compiler and fixing
91        some warnings.
92    
93    22. A caseless match of a UTF-8 character whose other case uses fewer bytes did
94        not work when the shorter character appeared right at the end of the
95        subject string.
96    
97    23. Added some (int) casts to non-JIT modules to reduce warnings on 64-bit
98        systems.
99    
100    24. Added PCRE_INFO_JITSIZE to pass on the value from (21) above, and also
101        output it when the /M option is used in pcretest.
102    
103    25. The CheckMan script was not being included in the distribution. Also, added
104        an explicit "perl" to run Perl scripts from the PrepareRelease script
105        because this is reportedly needed in Windows.
106    
107    26. If study data was being save in a file and studying had not found a set of
108        "starts with" bytes for the pattern, the data written to the file (though
109        never used) was taken from uninitialized memory and so caused valgrind to
110        complain.
111    
112    27. Updated RunTest.bat as provided by Sheri Pierce.
113    
114    28. Fixed a possible uninitialized memory bug in pcre_jit_compile.c.
115    
116    
117    Version 8.20 21-Oct-2011
118    ------------------------
119    
120    1.  Change 37 of 8.13 broke patterns like [:a]...[b:] because it thought it had
121        a POSIX class. After further experiments with Perl, which convinced me that
122        Perl has bugs and confusions, a closing square bracket is no longer allowed
123        in a POSIX name. This bug also affected patterns with classes that started
124        with full stops.
125    
126    2.  If a pattern such as /(a)b|ac/ is matched against "ac", there is no
127        captured substring, but while checking the failing first alternative,
128        substring 1 is temporarily captured. If the output vector supplied to
129        pcre_exec() was not big enough for this capture, the yield of the function
130        was still zero ("insufficient space for captured substrings"). This cannot
131        be totally fixed without adding another stack variable, which seems a lot
132        of expense for a edge case. However, I have improved the situation in cases
133        such as /(a)(b)x|abc/ matched against "abc", where the return code
134        indicates that fewer than the maximum number of slots in the ovector have
135        been set.
136    
137    3.  Related to (2) above: when there are more back references in a pattern than
138        slots in the output vector, pcre_exec() uses temporary memory during
139        matching, and copies in the captures as far as possible afterwards. It was
140        using the entire output vector, but this conflicts with the specification
141        that only 2/3 is used for passing back captured substrings. Now it uses
142        only the first 2/3, for compatibility. This is, of course, another edge
143        case.
144    
145    4.  Zoltan Herczeg's just-in-time compiler support has been integrated into the
146        main code base, and can be used by building with --enable-jit. When this is
147        done, pcregrep automatically uses it unless --disable-pcregrep-jit or the
148        runtime --no-jit option is given.
149    
150    5.  When the number of matches in a pcre_dfa_exec() run exactly filled the
151        ovector, the return from the function was zero, implying that there were
152        other matches that did not fit. The correct "exactly full" value is now
153        returned.
154    
155    6.  If a subpattern that was called recursively or as a subroutine contained
156        (*PRUNE) or any other control that caused it to give a non-standard return,
157        invalid errors such as "Error -26 (nested recursion at the same subject
158        position)" or even infinite loops could occur.
159    
160    7.  If a pattern such as /a(*SKIP)c|b(*ACCEPT)|/ was studied, it stopped
161        computing the minimum length on reaching *ACCEPT, and so ended up with the
162        wrong value of 1 rather than 0. Further investigation indicates that
163        computing a minimum subject length in the presence of *ACCEPT is difficult
164        (think back references, subroutine calls), and so I have changed the code
165        so that no minimum is registered for a pattern that contains *ACCEPT.
166    
167    8.  If (*THEN) was present in the first (true) branch of a conditional group,
168        it was not handled as intended. [But see 16 below.]
169    
170    9.  Replaced RunTest.bat and CMakeLists.txt with improved versions provided by
171        Sheri Pierce.
172    
173    10. A pathological pattern such as /(*ACCEPT)a/ was miscompiled, thinking that
174        the first byte in a match must be "a".
175    
176    11. Change 17 for 8.13 increased the recursion depth for patterns like
177        /a(?:.)*?a/ drastically. I've improved things by remembering whether a
178        pattern contains any instances of (*THEN). If it does not, the old
179        optimizations are restored. It would be nice to do this on a per-group
180        basis, but at the moment that is not feasible.
181    
182    12. In some environments, the output of pcretest -C is CRLF terminated. This
183        broke RunTest's code that checks for the link size. A single white space
184        character after the value is now allowed for.
185    
186    13. RunTest now checks for the "fr" locale as well as for "fr_FR" and "french".
187        For "fr", it uses the Windows-specific input and output files.
188    
189    14. If (*THEN) appeared in a group that was called recursively or as a
190        subroutine, it did not work as intended. [But see next item.]
191    
192    15. Consider the pattern /A (B(*THEN)C) | D/ where A, B, C, and D are complex
193        pattern fragments (but not containing any | characters). If A and B are
194        matched, but there is a failure in C so that it backtracks to (*THEN), PCRE
195        was behaving differently to Perl. PCRE backtracked into A, but Perl goes to
196        D. In other words, Perl considers parentheses that do not contain any |
197        characters to be part of a surrounding alternative, whereas PCRE was
198        treading (B(*THEN)C) the same as (B(*THEN)C|(*FAIL)) -- which Perl handles
199        differently. PCRE now behaves in the same way as Perl, except in the case
200        of subroutine/recursion calls such as (?1) which have in any case always
201        been different (but PCRE had them first :-).
202    
203    16. Related to 15 above: Perl does not treat the | in a conditional group as
204        creating alternatives. Such a group is treated in the same way as an
205        ordinary group without any | characters when processing (*THEN). PCRE has
206        been changed to match Perl's behaviour.
207    
208    17. If a user had set PCREGREP_COLO(U)R to something other than 1:31, the
209        RunGrepTest script failed.
210    
211    18. Change 22 for version 13 caused atomic groups to use more stack. This is
212        inevitable for groups that contain captures, but it can lead to a lot of
213        stack use in large patterns. The old behaviour has been restored for atomic
214        groups that do not contain any capturing parentheses.
215    
216    19. If the PCRE_NO_START_OPTIMIZE option was set for pcre_compile(), it did not
217        suppress the check for a minimum subject length at run time. (If it was
218        given to pcre_exec() or pcre_dfa_exec() it did work.)
219    
220    20. Fixed an ASCII-dependent infelicity in pcretest that would have made it
221        fail to work when decoding hex characters in data strings in EBCDIC
222        environments.
223    
224    21. It appears that in at least one Mac OS environment, the isxdigit() function
225        is implemented as a macro that evaluates to its argument more than once,
226        contravening the C 90 Standard (I haven't checked a later standard). There
227        was an instance in pcretest which caused it to go wrong when processing
228        \x{...} escapes in subject strings. The has been rewritten to avoid using
229        things like p++ in the argument of isxdigit().
230    
231    
232    Version 8.13 16-Aug-2011
233    ------------------------
234    
235    1.  The Unicode data tables have been updated to Unicode 6.0.0.
236    
237    2.  Two minor typos in pcre_internal.h have been fixed.
238    
239    3.  Added #include <string.h> to pcre_scanner_unittest.cc, pcrecpp.cc, and
240        pcrecpp_unittest.cc. They are needed for strcmp(), memset(), and strchr()
241        in some environments (e.g. Solaris 10/SPARC using Sun Studio 12U2).
242    
243    4.  There were a number of related bugs in the code for matching backrefences
244        caselessly in UTF-8 mode when codes for the characters concerned were
245        different numbers of bytes. For example, U+023A and U+2C65 are an upper
246        and lower case pair, using 2 and 3 bytes, respectively. The main bugs were:
247        (a) A reference to 3 copies of a 2-byte code matched only 2 of a 3-byte
248        code. (b) A reference to 2 copies of a 3-byte code would not match 2 of a
249        2-byte code at the end of the subject (it thought there wasn't enough data
250        left).
251    
252    5.  Comprehensive information about what went wrong is now returned by
253        pcre_exec() and pcre_dfa_exec() when the UTF-8 string check fails, as long
254        as the output vector has at least 2 elements. The offset of the start of
255        the failing character and a reason code are placed in the vector.
256    
257    6.  When the UTF-8 string check fails for pcre_compile(), the offset that is
258        now returned is for the first byte of the failing character, instead of the
259        last byte inspected. This is an incompatible change, but I hope it is small
260        enough not to be a problem. It makes the returned offset consistent with
261        pcre_exec() and pcre_dfa_exec().
262    
263    7.  pcretest now gives a text phrase as well as the error number when
264        pcre_exec() or pcre_dfa_exec() fails; if the error is a UTF-8 check
265        failure, the offset and reason code are output.
266    
267    8.  When \R was used with a maximizing quantifier it failed to skip backwards
268        over a \r\n pair if the subsequent match failed. Instead, it just skipped
269        back over a single character (\n). This seems wrong (because it treated the
270        two characters as a single entity when going forwards), conflicts with the
271        documentation that \R is equivalent to (?>\r\n|\n|...etc), and makes the
272        behaviour of \R* different to (\R)*, which also seems wrong. The behaviour
273        has been changed.
274    
275    9.  Some internal refactoring has changed the processing so that the handling
276        of the PCRE_CASELESS and PCRE_MULTILINE options is done entirely at compile
277        time (the PCRE_DOTALL option was changed this way some time ago: version
278        7.7 change 16). This has made it possible to abolish the OP_OPT op code,
279        which was always a bit of a fudge. It also means that there is one less
280        argument for the match() function, which reduces its stack requirements
281        slightly. This change also fixes an incompatibility with Perl: the pattern
282        (?i:([^b]))(?1) should not match "ab", but previously PCRE gave a match.
283    
284    10. More internal refactoring has drastically reduced the number of recursive
285        calls to match() for possessively repeated groups such as (abc)++ when
286        using pcre_exec().
287    
288    11. While implementing 10, a number of bugs in the handling of groups were
289        discovered and fixed:
290    
291        (?<=(a)+) was not diagnosed as invalid (non-fixed-length lookbehind).
292        (a|)*(?1) gave a compile-time internal error.
293        ((a|)+)+  did not notice that the outer group could match an empty string.
294        (^a|^)+   was not marked as anchored.
295        (.*a|.*)+ was not marked as matching at start or after a newline.
296    
297    12. Yet more internal refactoring has removed another argument from the match()
298        function. Special calls to this function are now indicated by setting a
299        value in a variable in the "match data" data block.
300    
301    13. Be more explicit in pcre_study() instead of relying on "default" for
302        opcodes that mean there is no starting character; this means that when new
303        ones are added and accidentally left out of pcre_study(), testing should
304        pick them up.
305    
306    14. The -s option of pcretest has been documented for ages as being an old
307        synonym of -m (show memory usage). I have changed it to mean "force study
308        for every regex", that is, assume /S for every regex. This is similar to -i
309        and -d etc. It's slightly incompatible, but I'm hoping nobody is still
310        using it. It makes it easier to run collections of tests with and without
311        study enabled, and thereby test pcre_study() more easily. All the standard
312        tests are now run with and without -s (but some patterns can be marked as
313        "never study" - see 20 below).
314    
315    15. When (*ACCEPT) was used in a subpattern that was called recursively, the
316        restoration of the capturing data to the outer values was not happening
317        correctly.
318    
319    16. If a recursively called subpattern ended with (*ACCEPT) and matched an
320        empty string, and PCRE_NOTEMPTY was set, pcre_exec() thought the whole
321        pattern had matched an empty string, and so incorrectly returned a no
322        match.
323    
324    17. There was optimizing code for the last branch of non-capturing parentheses,
325        and also for the obeyed branch of a conditional subexpression, which used
326        tail recursion to cut down on stack usage. Unfortunately, now that there is
327        the possibility of (*THEN) occurring in these branches, tail recursion is
328        no longer possible because the return has to be checked for (*THEN). These
329        two optimizations have therefore been removed. [But see 8.20/11 above.]
330    
331    18. If a pattern containing \R was studied, it was assumed that \R always
332        matched two bytes, thus causing the minimum subject length to be
333        incorrectly computed because \R can also match just one byte.
334    
335    19. If a pattern containing (*ACCEPT) was studied, the minimum subject length
336        was incorrectly computed.
337    
338    20. If /S is present twice on a test pattern in pcretest input, it now
339        *disables* studying, thereby overriding the use of -s on the command line
340        (see 14 above). This is necessary for one or two tests to keep the output
341        identical in both cases.
342    
343    21. When (*ACCEPT) was used in an assertion that matched an empty string and
344        PCRE_NOTEMPTY was set, PCRE applied the non-empty test to the assertion.
345    
346    22. When an atomic group that contained a capturing parenthesis was
347        successfully matched, but the branch in which it appeared failed, the
348        capturing was not being forgotten if a higher numbered group was later
349        captured. For example, /(?>(a))b|(a)c/ when matching "ac" set capturing
350        group 1 to "a", when in fact it should be unset. This applied to multi-
351        branched capturing and non-capturing groups, repeated or not, and also to
352        positive assertions (capturing in negative assertions does not happen
353        in PCRE) and also to nested atomic groups.
354    
355    23. Add the ++ qualifier feature to pcretest, to show the remainder of the
356        subject after a captured substring, to make it easier to tell which of a
357        number of identical substrings has been captured.
358    
359    24. The way atomic groups are processed by pcre_exec() has been changed so that
360        if they are repeated, backtracking one repetition now resets captured
361        values correctly. For example, if ((?>(a+)b)+aabab) is matched against
362        "aaaabaaabaabab" the value of captured group 2 is now correctly recorded as
363        "aaa". Previously, it would have been "a". As part of this code
364        refactoring, the way recursive calls are handled has also been changed.
365    
366    25. If an assertion condition captured any substrings, they were not passed
367        back unless some other capturing happened later. For example, if
368        (?(?=(a))a) was matched against "a", no capturing was returned.
369    
370    26. When studying a pattern that contained subroutine calls or assertions,
371        the code for finding the minimum length of a possible match was handling
372        direct recursions such as (xxx(?1)|yyy) but not mutual recursions (where
373        group 1 called group 2 while simultaneously a separate group 2 called group
374        1). A stack overflow occurred in this case. I have fixed this by limiting
375        the recursion depth to 10.
376    
377    27. Updated RunTest.bat in the distribution to the version supplied by Tom
378        Fortmann. This supports explicit test numbers on the command line, and has
379        argument validation and error reporting.
380    
381    28. An instance of \X with an unlimited repeat could fail if at any point the
382        first character it looked at was a mark character.
383    
384    29. Some minor code refactoring concerning Unicode properties and scripts
385        should reduce the stack requirement of match() slightly.
386    
387    30. Added the '=' option to pcretest to check the setting of unused capturing
388        slots at the end of the pattern, which are documented as being -1, but are
389        not included in the return count.
390    
391    31. If \k was not followed by a braced, angle-bracketed, or quoted name, PCRE
392        compiled something random. Now it gives a compile-time error (as does
393        Perl).
394    
395    32. A *MARK encountered during the processing of a positive assertion is now
396        recorded and passed back (compatible with Perl).
397    
398    33. If --only-matching or --colour was set on a pcregrep call whose pattern
399        had alternative anchored branches, the search for a second match in a line
400        was done as if at the line start. Thus, for example, /^01|^02/ incorrectly
401        matched the line "0102" twice. The same bug affected patterns that started
402        with a backwards assertion. For example /\b01|\b02/ also matched "0102"
403        twice.
404    
405    34. Previously, PCRE did not allow quantification of assertions. However, Perl
406        does, and because of capturing effects, quantifying parenthesized
407        assertions may at times be useful. Quantifiers are now allowed for
408        parenthesized assertions.
409    
410    35. A minor code tidy in pcre_compile() when checking options for \R usage.
411    
412    36. \g was being checked for fancy things in a character class, when it should
413        just be a literal "g".
414    
415    37. PCRE was rejecting [:a[:digit:]] whereas Perl was not. It seems that the
416        appearance of a nested POSIX class supersedes an apparent external class.
417        For example, [:a[:digit:]b:] matches "a", "b", ":", or a digit. Also,
418        unescaped square brackets may also appear as part of class names. For
419        example, [:a[:abc]b:] gives unknown class "[:abc]b:]". PCRE now behaves
420        more like Perl. (But see 8.20/1 above.)
421    
422    38. PCRE was giving an error for \N with a braced quantifier such as {1,} (this
423        was because it thought it was \N{name}, which is not supported).
424    
425    39. Add minix to OS list not supporting the -S option in pcretest.
426    
427    40. PCRE tries to detect cases of infinite recursion at compile time, but it
428        cannot analyze patterns in sufficient detail to catch mutual recursions
429        such as ((?1))((?2)). There is now a runtime test that gives an error if a
430        subgroup is called recursively as a subpattern for a second time at the
431        same position in the subject string. In previous releases this might have
432        been caught by the recursion limit, or it might have run out of stack.
433    
434    41. A pattern such as /(?(R)a+|(?R)b)/ is quite safe, as the recursion can
435        happen only once. PCRE was, however incorrectly giving a compile time error
436        "recursive call could loop indefinitely" because it cannot analyze the
437        pattern in sufficient detail. The compile time test no longer happens when
438        PCRE is compiling a conditional subpattern, but actual runaway loops are
439        now caught at runtime (see 40 above).
440    
441    42. It seems that Perl allows any characters other than a closing parenthesis
442        to be part of the NAME in (*MARK:NAME) and other backtracking verbs. PCRE
443        has been changed to be the same.
444    
445    43. Updated configure.ac to put in more quoting round AC_LANG_PROGRAM etc. so
446        as not to get warnings when autogen.sh is called. Also changed
447        AC_PROG_LIBTOOL (deprecated) to LT_INIT (the current macro).
448    
449    44. To help people who use pcregrep to scan files containing exceedingly long
450        lines, the following changes have been made:
451    
452        (a) The default value of the buffer size parameter has been increased from
453            8K to 20K. (The actual buffer used is three times this size.)
454    
455        (b) The default can be changed by ./configure --with-pcregrep-bufsize when
456            PCRE is built.
457    
458        (c) A --buffer-size=n option has been added to pcregrep, to allow the size
459            to be set at run time.
460    
461        (d) Numerical values in pcregrep options can be followed by K or M, for
462            example --buffer-size=50K.
463    
464        (e) If a line being scanned overflows pcregrep's buffer, an error is now
465            given and the return code is set to 2.
466    
467    45. Add a pointer to the latest mark to the callout data block.
468    
469    46. The pattern /.(*F)/, when applied to "abc" with PCRE_PARTIAL_HARD, gave a
470        partial match of an empty string instead of no match. This was specific to
471        the use of ".".
472    
473    47. The pattern /f.*/8s, when applied to "for" with PCRE_PARTIAL_HARD, gave a
474        complete match instead of a partial match. This bug was dependent on both
475        the PCRE_UTF8 and PCRE_DOTALL options being set.
476    
477    48. For a pattern such as /\babc|\bdef/ pcre_study() was failing to set up the
478        starting byte set, because \b was not being ignored.
479    
480    
481    Version 8.12 15-Jan-2011
482    ------------------------
483    
484    1.  Fixed some typos in the markup of the man pages, and wrote a script that
485        checks for such things as part of the documentation building process.
486    
487    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
488        --match-limit and --recursion-limit options (added for 8.11). In
489        particular, this made one of the standard tests fail. (The integer value
490        went into the wrong half of a long int.)
491    
492    3.  If the --colour option was given to pcregrep with -v (invert match), it
493        did strange things, either producing crazy output, or crashing. It should,
494        of course, ignore a request for colour when reporting lines that do not
495        match.
496    
497    4.  Another pcregrep bug caused similar problems if --colour was specified with
498        -M (multiline) and the pattern match finished with a line ending.
499    
500    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
501        matched in multiline mode, the following line was shown as part of the
502        match. This seems wrong, so I have changed it.
503    
504    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
505        the check for further matches in the same line (so they could be coloured)
506        to overrun the end of the current line. If another match was found, it was
507        incorrectly shown (and then shown again when found in the next line).
508    
509    7.  If pcregrep was compiled under Windows, there was a reference to the
510        function pcregrep_exit() before it was defined. I am assuming this was
511        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
512        reported by a user. I've moved the definition above the reference.
513    
514    
515    Version 8.11 10-Dec-2010
516    ------------------------
517    
518    1.  (*THEN) was not working properly if there were untried alternatives prior
519        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
520        backtracked to try for "b" instead of moving to the next alternative branch
521        at the same level (in this case, to look for "c"). The Perl documentation
522        is clear that when (*THEN) is backtracked onto, it goes to the "next
523        alternative in the innermost enclosing group".
524    
525    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
526        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
527        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
528        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
529        (*THEN).
530    
531    3.  If \s appeared in a character class, it removed the VT character from
532        the class, even if it had been included by some previous item, for example
533        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
534        of \s, but is part of the POSIX "space" class.)
535    
536    4.  A partial match never returns an empty string (because you can always
537        match an empty string at the end of the subject); however the checking for
538        an empty string was starting at the "start of match" point. This has been
539        changed to the "earliest inspected character" point, because the returned
540        data for a partial match starts at this character. This means that, for
541        example, /(?<=abc)def/ gives a partial match for the subject "abc"
542        (previously it gave "no match").
543    
544    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
545        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
546        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
547        has an implication that the given string is incomplete (because a partial
548        match is preferred over a full match). For this reason, these items now
549        give a partial match in this situation. [Aside: previously, the one case
550        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
551        match rather than a full match, which was wrong by the old rules, but is
552        now correct.]
553    
554    6.  There was a bug in the handling of #-introduced comments, recognized when
555        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
556        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
557        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
558        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
559        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
560        places in pcre_compile().
561    
562    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
563        comments when looking ahead for named forward references to subpatterns,
564        the only newline sequence it recognized was NL. It now handles newlines
565        according to the set newline convention.
566    
567    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
568        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
569        cater for a lack of strerror(). These oversights have been fixed.
570    
571    9.  Added --match-limit and --recursion-limit to pcregrep.
572    
573    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
574    
575    11. When the -o option was used, pcregrep was setting a return code of 1, even
576        when matches were found, and --line-buffered was not being honoured.
577    
578    12. Added an optional parentheses number to the -o and --only-matching options
579        of pcregrep.
580    
581    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
582        can match an empty string. The code to do it in pcretest and pcredemo
583        needed fixing:
584    
585        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
586            only one byte after an empty string match just before CRLF (this case
587            just got forgotten; "any" and "anycrlf" were OK).
588    
589        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
590            mode when an empty string match preceded an ASCII character followed by
591            a non-ASCII character. (The code for advancing by one character rather
592            than one byte was nonsense.)
593    
594        (c) The pcredemo.c sample program did not have any code at all to handle
595            the cases when CRLF is a valid newline sequence.
596    
597    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
598        as a starting offset was within the subject string. There is now a new
599        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
600        negative or greater than the length of the string. In order to test this,
601        pcretest is extended to allow the setting of negative starting offsets.
602    
603    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
604        starting offset points to the beginning of a UTF-8 character was
605        unnecessarily clumsy. I tidied it up.
606    
607    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
608        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
609    
610    17. Nobody had reported that the --include_dir option, which was added in
611        release 7.7 should have been called --include-dir (hyphen, not underscore)
612        for compatibility with GNU grep. I have changed it to --include-dir, but
613        left --include_dir as an undocumented synonym, and the same for
614        --exclude-dir, though that is not available in GNU grep, at least as of
615        release 2.5.4.
616    
617    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
618        characters from a string of bytes) have been redefined so as not to use
619        loops, in order to improve performance in some environments. At the same
620        time, I abstracted some of the common code into auxiliary macros to save
621        repetition (this should not affect the compiled code).
622    
623    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
624        compile-time error is now given if \c is not followed by an ASCII
625        character, that is, a byte less than 128. (In EBCDIC mode, the code is
626        different, and any byte value is allowed.)
627    
628    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
629        START_OPTIMIZE option, which is now allowed at compile time - but just
630        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
631        to pcregrep and other applications that have no direct access to PCRE
632        options. The new /Y option in pcretest sets this option when calling
633        pcre_compile().
634    
635    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
636        back references. Groups containing recursive back references were forced to
637        be atomic by that change, but in the case of named groups, the amount of
638        memory required was incorrectly computed, leading to "Failed: internal
639        error: code overflow". This has been fixed.
640    
641    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
642        pcretest.c, to avoid build problems in some Borland environments.
643    
644    
645    Version 8.10 25-Jun-2010
646    ------------------------
647    
648    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
649        THEN.
650    
651    2.  (*ACCEPT) was not working when inside an atomic group.
652    
653    3.  Inside a character class, \B is treated as a literal by default, but
654        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
655        causes the error). The code is unchanged, but I tidied the documentation.
656    
657    4.  Inside a character class, PCRE always treated \R and \X as literals,
658        whereas Perl faults them if its -w option is set. I have changed PCRE so
659        that it faults them when PCRE_EXTRA is set.
660    
661    5.  Added support for \N, which always matches any character other than
662        newline. (It is the same as "." when PCRE_DOTALL is not set.)
663    
664    6.  When compiling pcregrep with newer versions of gcc which may have
665        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
666        declared with attribute warn_unused_result" were given. Just casting the
667        result to (void) does not stop the warnings; a more elaborate fudge is
668        needed. I've used a macro to implement this.
669    
670    7.  Minor change to pcretest.c to avoid a compiler warning.
671    
672    8.  Added four artifical Unicode properties to help with an option to make
673        \s etc use properties (see next item). The new properties are: Xan
674        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
675    
676    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
677        use Unicode properties. (*UCP) at the start of a pattern can be used to set
678        this option. Modified pcretest to add /W to test this facility. Added
679        REG_UCP to make it available via the POSIX interface.
680    
681    10. Added --line-buffered to pcregrep.
682    
683    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
684        studied, and the match started with a letter with a code point greater than
685        127 whose first byte was different to the first byte of the other case of
686        the letter, the other case of this starting letter was not recognized
687        (#976).
688    
689    12. If a pattern that was studied started with a repeated Unicode property
690        test, for example, \p{Nd}+, there was the theoretical possibility of
691        setting up an incorrect bitmap of starting bytes, but fortunately it could
692        not have actually happened in practice until change 8 above was made (it
693        added property types that matched character-matching opcodes).
694    
695    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
696        possible starting bytes for non-anchored patterns.
697    
698    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
699        \R, and also a number of cases that involve Unicode properties, both
700        explicit and implicit when PCRE_UCP is set.
701    
702    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
703        input, it could crash or give wrong results if characters with values
704        greater than 0xc0 were present in the subject string. (Detail: it assumed
705        UTF-8 input when processing these items.)
706    
707    16. Added a lot of (int) casts to avoid compiler warnings in systems where
708        size_t is 64-bit (#991).
709    
710    17. Added a check for running out of memory when PCRE is compiled with
711        --disable-stack-for-recursion (#990).
712    
713    18. If the last data line in a file for pcretest does not have a newline on
714        the end, a newline was missing in the output.
715    
716    19. The default pcre_chartables.c file recognizes only ASCII characters (values
717        less than 128) in its various bitmaps. However, there is a facility for
718        generating tables according to the current locale when PCRE is compiled. It
719        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
720        characters, are recognized by isspace() and therefore were getting set in
721        these tables, and indeed these tables seem to approximate to ISO 8859. This
722        caused a problem in UTF-8 mode when pcre_study() was used to create a list
723        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
724        which of course cannot start UTF-8 characters. I have changed the code so
725        that only real ASCII characters (less than 128) and the correct starting
726        bytes for UTF-8 encodings are set for characters greater than 127 when in
727        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
728        altogether.)
729    
730    20. Added the /T option to pcretest so as to be able to run tests with non-
731        standard character tables, thus making it possible to include the tests
732        used for 19 above in the standard set of tests.
733    
734    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
735        reference to a subpattern the other side of a comment that contains an
736        opening parenthesis caused either an internal compiling error, or a
737        reference to the wrong subpattern.
738    
739    
740    Version 8.02 19-Mar-2010
741    ------------------------
742    
743    1.  The Unicode data tables have been updated to Unicode 5.2.0.
744    
745    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
746        configured.
747    
748    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
749        original author of that file, following a query about its status.
750    
751    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
752        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
753    
754    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
755        quantifier applied to a forward-referencing subroutine call, could compile
756        incorrect code or give the error "internal error: previously-checked
757        referenced subpattern not found".
758    
759    6.  Both MS Visual Studio and Symbian OS have problems with initializing
760        variables to point to external functions. For these systems, therefore,
761        pcre_malloc etc. are now initialized to local functions that call the
762        relevant global functions.
763    
764    7.  There were two entries missing in the vectors called coptable and poptable
765        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
766        I've fixed the data, and added a kludgy way of testing at compile time that
767        the lengths are correct (equal to the number of opcodes).
768    
769    8.  Following on from 7, I added a similar kludge to check the length of the
770        eint vector in pcreposix.c.
771    
772    9.  Error texts for pcre_compile() are held as one long string to avoid too
773        much relocation at load time. To find a text, the string is searched,
774        counting zeros. There was no check for running off the end of the string,
775        which could happen if a new error number was added without updating the
776        string.
777    
778    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
779    
780    11. \K was not working if it appeared in an atomic group or in a group that
781        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
782        \K is "not well defined" if used in an assertion. PCRE now accepts it if
783        the assertion is positive, but not if it is negative.
784    
785    12. Change 11 fortuitously reduced the size of the stack frame used in the
786        "match()" function of pcre_exec.c by one pointer. Forthcoming
787        implementation of support for (*MARK) will need an extra pointer on the
788        stack; I have reserved it now, so that the stack frame size does not
789        decrease.
790    
791    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
792        item in branch that calls a recursion is a subroutine call - as in the
793        second branch in the above example - was incorrectly given the compile-
794        time error "recursive call could loop indefinitely" because pcre_compile()
795        was not correctly checking the subroutine for matching a non-empty string.
796    
797    14. The checks for overrunning compiling workspace could trigger after an
798        overrun had occurred. This is a "should never occur" error, but it can be
799        triggered by pathological patterns such as hundreds of nested parentheses.
800        The checks now trigger 100 bytes before the end of the workspace.
801    
802    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
803    
804    
805    Version 8.01 19-Jan-2010
806    ------------------------
807    
808    1.  If a pattern contained a conditional subpattern with only one branch (in
809        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
810        computed the wrong minimum data length (which is of course zero for such
811        subpatterns). This could cause incorrect "no match" results.
812    
813    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
814        the pattern is reset in the first branch, pcre_compile() failed with
815        "internal error: code overflow at offset...". This happened only when
816        the reset was to the original external option setting. (An optimization
817        abstracts leading options settings into an external setting, which was the
818        cause of this.)
819    
820    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
821        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
822        assertion pattern did not match (meaning that the assertion was true), it
823        was incorrectly treated as false if the SKIP had been reached during the
824        matching. This also applied to assertions used as conditions.
825    
826    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
827        assertion subpattern, including such a pattern used as a condition,
828        unpredictable results occurred, instead of the error return
829        PCRE_ERROR_DFA_UITEM.
830    
831    5.  The C++ GlobalReplace function was not working like Perl for the special
832        situation when an empty string is matched. It now does the fancy magic
833        stuff that is necessary.
834    
835    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
836        removed. (These were left over from very, very early versions of PCRE.)
837    
838    7.  Some cosmetic changes to the code to make life easier when compiling it
839        as part of something else:
840    
841        (a) Change DEBUG to PCRE_DEBUG.
842    
843        (b) In pcre_compile(), rename the member of the "branch_chain" structure
844            called "current" as "current_branch", to prevent a collision with the
845            Linux macro when compiled as a kernel module.
846    
847        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
848            prevent a collision with the Linux macro when compiled as a kernel
849            module.
850    
851    8.  In pcre_compile() there are some checks for integer overflows that used to
852        cast potentially large values to (double). This has been changed to that
853        when building, a check for int64_t is made, and if it is found, it is used
854        instead, thus avoiding the use of floating point arithmetic. (There is no
855        other use of FP in PCRE.) If int64_t is not found, the fallback is to
856        double.
857    
858    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
859        2005 (difference between two addresses compared to an unsigned value).
860    
861    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
862        custom one, because of the following reported problem in Windows:
863    
864          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
865              under Win32.
866          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
867              therefore missing the function definition.
868          - The compiler thus generates a "C" signature for the test function.
869          - The linker fails to find the "C" function.
870          - PCRE fails to configure if asked to do so against libbz2.
871    
872    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
873        messages were output:
874    
875          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
876          rerunning libtoolize, to keep the correct libtool macros in-tree.
877          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
878    
879        I have done both of these things.
880    
881    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
882        most of the time, it *can* run out if it is given a pattern that contains a
883        runaway infinite recursion. I updated the discussion in the pcrestack man
884        page.
885    
886    13. Now that we have gone to the x.xx style of version numbers, the minor
887        version may start with zero. Using 08 or 09 is a bad idea because users
888        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
889        interpreted as invalid octal numbers. I've updated the previous comment in
890        configure.ac, and also added a check that gives an error if 08 or 09 are
891        used.
892    
893    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
894        causing partial matching to fail when the end of the subject matched \W
895        in a UTF-8 pattern where \W was quantified with a minimum of 3.
896    
897    15. There were some discrepancies between the declarations in pcre_internal.h
898        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
899        their definitions. The declarations used "const uschar *" and the
900        definitions used USPTR. Even though USPTR is normally defined as "const
901        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
902        reported that: "This difference in casting confuses some C++ compilers, for
903        example, SunCC recognizes above declarations as different functions and
904        generates broken code for hbpcre." I have changed the declarations to use
905        USPTR.
906    
907    16. GNU libtool is named differently on some systems. The autogen.sh script now
908        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
909        (FreeBSD).
910    
911    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
912        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
913        comment: "Figure out how to create a longlong from a string: strtoll and
914        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
915        instance, but it only takes 2 args instead of 3!"
916    
917    18. A subtle bug concerned with back references has been fixed by a change of
918        specification, with a corresponding code fix. A pattern such as
919        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
920        refers, was giving matches when it shouldn't. For example, xa=xaaa would
921        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
922        same bug. Such groups have to be quantified to be useful, or contained
923        inside another quantified group. (If there's no repetition, the reference
924        can never match.) The problem arises because, having left the group and
925        moved on to the rest of the pattern, a later failure that backtracks into
926        the group uses the captured value from the final iteration of the group
927        rather than the correct earlier one. I have fixed this in PCRE by forcing
928        any group that contains a reference to itself to be an atomic group; that
929        is, there cannot be any backtracking into it once it has completed. This is
930        similar to recursive and subroutine calls.
931    
932    
933    Version 8.00 19-Oct-09
934  ----------------------  ----------------------
935    
936  1.  The table for translating pcre_compile() error codes into POSIX error codes  1.  The table for translating pcre_compile() error codes into POSIX error codes
937      was out-of-date, and there was no check on the pcre_compile() error code      was out-of-date, and there was no check on the pcre_compile() error code
938      being within the table. This could lead to an OK return being given in      being within the table. This could lead to an OK return being given in
939      error.      error.
940    
941  2.  Changed the call to open a subject file in pcregrep from fopen(pathname,  2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
942      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests      "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
943      in a Windows environment.      in a Windows environment.
944    
945  3.  The pcregrep --count option prints the count for each file even when it is  3.  The pcregrep --count option prints the count for each file even when it is
946      zero, as does GNU grep. However, pcregrep was also printing all files when      zero, as does GNU grep. However, pcregrep was also printing all files when
947      --files-with-matches was added. Now, when both options are given, it prints      --files-with-matches was added. Now, when both options are given, it prints
948      counts only for those files that have at least one match. (GNU grep just      counts only for those files that have at least one match. (GNU grep just
949      prints the file name in this circumstance, but including the count seems      prints the file name in this circumstance, but including the count seems
950      more useful - otherwise, why use --count?) Also ensured that the      more useful - otherwise, why use --count?) Also ensured that the
951      combination -clh just lists non-zero counts, with no names.      combination -clh just lists non-zero counts, with no names.
952    
953  4.  The long form of the pcregrep -F option was incorrectly implemented as  4.  The long form of the pcregrep -F option was incorrectly implemented as
954      --fixed_strings instead of --fixed-strings. This is an incompatible change,      --fixed_strings instead of --fixed-strings. This is an incompatible change,
955      but it seems right to fix it, and I didn't think it was worth preserving      but it seems right to fix it, and I didn't think it was worth preserving
956      the old behaviour.      the old behaviour.
957    
958  5.  The command line items --regex=pattern and --regexp=pattern were not  5.  The command line items --regex=pattern and --regexp=pattern were not
959      recognized by pcregrep, which required --regex pattern or --regexp pattern      recognized by pcregrep, which required --regex pattern or --regexp pattern
960      (with a space rather than an '='). The man page documented the '=' forms,      (with a space rather than an '='). The man page documented the '=' forms,
961      which are compatible with GNU grep; these now work.      which are compatible with GNU grep; these now work.
962    
963  6.  No libpcreposix.pc file was created for pkg-config; there was just  6.  No libpcreposix.pc file was created for pkg-config; there was just
964      libpcre.pc and libpcrecpp.pc. The omission has been rectified.      libpcre.pc and libpcrecpp.pc. The omission has been rectified.
965    
966  7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size  7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
967      when UCP support is not needed, by modifying the Python script that      when UCP support is not needed, by modifying the Python script that
968      generates it from Unicode data files. This should not matter if the module      generates it from Unicode data files. This should not matter if the module
969      is correctly used as a library, but I received one complaint about 50K of      is correctly used as a library, but I received one complaint about 50K of
970      unwanted data. My guess is that the person linked everything into his      unwanted data. My guess is that the person linked everything into his
971      program rather than using a library. Anyway, it does no harm.      program rather than using a library. Anyway, it does no harm.
972    
973  8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger  8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
974      was a minimum greater than 1 for a wide character in a possessive      was a minimum greater than 1 for a wide character in a possessive
975      repetition. Chaos could result.      repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
976        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
977        character. Chaos in the form of incorrect output or a compiling loop could
978        result.
979    
980  9.  The restrictions on what a pattern can contain when partial matching is  9.  The restrictions on what a pattern can contain when partial matching is
981      requested for pcre_exec() have been removed. All patterns can now be      requested for pcre_exec() have been removed. All patterns can now be
982      partially matched by this function. In addition, if there are at least two      partially matched by this function. In addition, if there are at least two
983      slots in the offset vector, the offsets of the first-encountered partial      slots in the offset vector, the offset of the earliest inspected character
984      match are set in them when PCRE_ERROR_PARTIAL is returned.      for the match and the offset of the end of the subject are set in them when
985        PCRE_ERROR_PARTIAL is returned.
986    
987  10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is  10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
988      synonymous with PCRE_PARTIAL, for backwards compatibility, and      synonymous with PCRE_PARTIAL, for backwards compatibility, and
989      PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,      PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
990      and may be more useful for multi-segment matching, especially with      and may be more useful for multi-segment matching.
991      pcre_exec().  
992    11. Partial matching with pcre_exec() is now more intuitive. A partial match
993  11. Partial matching with pcre_exec() is now more intuitive. A partial match      used to be given if ever the end of the subject was reached; now it is
994      used to be given if ever the end of the subject was reached; now it is      given only if matching could not proceed because another character was
995      given only if matching could not proceed because another character was      needed. This makes a difference in some odd cases such as Z(*FAIL) with the
996      needed. This makes a difference in some odd cases such as Z(*FAIL) with the      string "Z", which now yields "no match" instead of "partial match". In the
997      string "Z", which now yields "no match" instead of "partial match". In the      case of pcre_dfa_exec(), "no match" is given if every matching path for the
998      case of pcre_dfa_exec(), "no match" is given if every matching path for the      final character ended with (*FAIL).
999      final character ended with (*FAIL).  
   
1000  12. Restarting a match using pcre_dfa_exec() after a partial match did not work  12. Restarting a match using pcre_dfa_exec() after a partial match did not work
1001      if the pattern had a "must contain" character that was already found in the      if the pattern had a "must contain" character that was already found in the
1002      earlier partial match, unless partial matching was again requested. For      earlier partial match, unless partial matching was again requested. For
1003      example, with the pattern /dog.(body)?/, the "must contain" character is      example, with the pattern /dog.(body)?/, the "must contain" character is
1004      "g". If the first part-match was for the string "dog", restarting with      "g". If the first part-match was for the string "dog", restarting with
1005      "sbody" failed.      "sbody" failed. This bug has been fixed.
1006    
1007  13. Added a pcredemo man page, created automatically from the pcredemo.c file,  13. The string returned by pcre_dfa_exec() after a partial match has been
1008      so that the demonstration program is easily available in environments where      changed so that it starts at the first inspected character rather than the
1009      PCRE has not been installed from source.      first character of the match. This makes a difference only if the pattern
1010        starts with a lookbehind assertion or \b or \B (\K is not supported by
1011        pcre_dfa_exec()). It's an incompatible change, but it makes the two
1012        matching functions compatible, and I think it's the right thing to do.
1013    
1014    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
1015        so that the demonstration program is easily available in environments where
1016        PCRE has not been installed from source.
1017    
1018    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
1019        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
1020        library.
1021    
1022    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
1023        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
1024        is not the first non-POSIX option to be added. Clearly some people find
1025        these options useful.
1026    
1027    17. If a caller to the POSIX matching function regexec() passes a non-zero
1028        value for nmatch with a NULL value for pmatch, the value of
1029        nmatch is forced to zero.
1030    
1031    18. RunGrepTest did not have a test for the availability of the -u option of
1032        the diff command, as RunTest does. It now checks in the same way as
1033        RunTest, and also checks for the -b option.
1034    
1035    19. If an odd number of negated classes containing just a single character
1036        interposed, within parentheses, between a forward reference to a named
1037        subpattern and the definition of the subpattern, compilation crashed with
1038        an internal error, complaining that it could not find the referenced
1039        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
1040        [The bug was that it was starting one character too far in when skipping
1041        over the character class, thus treating the ] as data rather than
1042        terminating the class. This meant it could skip too much.]
1043    
1044    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
1045        /g option in pcretest when the pattern contains \K, which makes it possible
1046        to have an empty string match not at the start, even when the pattern is
1047        anchored. Updated pcretest and pcredemo to use this option.
1048    
1049    21. If the maximum number of capturing subpatterns in a recursion was greater
1050        than the maximum at the outer level, the higher number was returned, but
1051        with unset values at the outer level. The correct (outer level) value is
1052        now given.
1053    
1054    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
1055        PCRE did not set those parentheses (unlike Perl). I have now found a way to
1056        make it do so. The string so far is captured, making this feature
1057        compatible with Perl.
1058    
1059    23. The tests have been re-organized, adding tests 11 and 12, to make it
1060        possible to check the Perl 5.10 features against Perl 5.10.
1061    
1062    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
1063        pattern matches a fixed length string. PCRE did not allow this; now it
1064        does. Neither allows recursion.
1065    
1066    25. I finally figured out how to implement a request to provide the minimum
1067        length of subject string that was needed in order to match a given pattern.
1068        (It was back references and recursion that I had previously got hung up
1069        on.) This code has now been added to pcre_study(); it finds a lower bound
1070        to the length of subject needed. It is not necessarily the greatest lower
1071        bound, but using it to avoid searching strings that are too short does give
1072        some useful speed-ups. The value is available to calling programs via
1073        pcre_fullinfo().
1074    
1075    26. While implementing 25, I discovered to my embarrassment that pcretest had
1076        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
1077        study optimizations had never been tested with that matching function.
1078        Oops. What is worse, even when it was passed study data, there was a bug in
1079        pcre_dfa_exec() that meant it never actually used it. Double oops. There
1080        were also very few tests of studied patterns with pcre_dfa_exec().
1081    
1082    27. If (?| is used to create subpatterns with duplicate numbers, they are now
1083        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
1084        on the other side of the coin, they are no longer allowed to have different
1085        names, because these cannot be distinguished in PCRE, and this has caused
1086        confusion. (This is a difference from Perl.)
1087    
1088    28. When duplicate subpattern names are present (necessarily with different
1089        numbers, as required by 27 above), and a test is made by name in a
1090        conditional pattern, either for a subpattern having been matched, or for
1091        recursion in such a pattern, all the associated numbered subpatterns are
1092        tested, and the overall condition is true if the condition is true for any
1093        one of them. This is the way Perl works, and is also more like the way
1094        testing by number works.
1095    
1096    
1097  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09
1098  ---------------------  ---------------------

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