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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 8.00 ??-???-??  Version 8.13 30-Apr-2011
5    ------------------------
6    
7    1.  The Unicode data tables have been updated to Unicode 6.0.0.
8    
9    
10    Version 8.12 15-Jan-2011
11    ------------------------
12    
13    1.  Fixed some typos in the markup of the man pages, and wrote a script that
14        checks for such things as part of the documentation building process.
15    
16    2.  On a big-endian 64-bit system, pcregrep did not correctly process the
17        --match-limit and --recursion-limit options (added for 8.11). In
18        particular, this made one of the standard tests fail. (The integer value
19        went into the wrong half of a long int.)
20    
21    3.  If the --colour option was given to pcregrep with -v (invert match), it
22        did strange things, either producing crazy output, or crashing. It should,
23        of course, ignore a request for colour when reporting lines that do not
24        match.
25    
26    4.  Another pcregrep bug caused similar problems if --colour was specified with
27        -M (multiline) and the pattern match finished with a line ending.
28    
29    5.  In pcregrep, when a pattern that ended with a literal newline sequence was
30        matched in multiline mode, the following line was shown as part of the
31        match. This seems wrong, so I have changed it.
32    
33    6.  Another pcregrep bug in multiline mode, when --colour was specified, caused
34        the check for further matches in the same line (so they could be coloured)
35        to overrun the end of the current line. If another match was found, it was
36        incorrectly shown (and then shown again when found in the next line).
37    
38    7.  If pcregrep was compiled under Windows, there was a reference to the
39        function pcregrep_exit() before it was defined. I am assuming this was
40        the cause of the "error C2371: 'pcregrep_exit' : redefinition;" that was
41        reported by a user. I've moved the definition above the reference.
42    
43    
44    Version 8.11 10-Dec-2010
45    ------------------------
46    
47    1.  (*THEN) was not working properly if there were untried alternatives prior
48        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
49        backtracked to try for "b" instead of moving to the next alternative branch
50        at the same level (in this case, to look for "c"). The Perl documentation
51        is clear that when (*THEN) is backtracked onto, it goes to the "next
52        alternative in the innermost enclosing group".
53    
54    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
55        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
56        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
57        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
58        (*THEN).
59    
60    3.  If \s appeared in a character class, it removed the VT character from
61        the class, even if it had been included by some previous item, for example
62        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
63        of \s, but is part of the POSIX "space" class.)
64    
65    4.  A partial match never returns an empty string (because you can always
66        match an empty string at the end of the subject); however the checking for
67        an empty string was starting at the "start of match" point. This has been
68        changed to the "earliest inspected character" point, because the returned
69        data for a partial match starts at this character. This means that, for
70        example, /(?<=abc)def/ gives a partial match for the subject "abc"
71        (previously it gave "no match").
72    
73    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
74        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
75        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
76        has an implication that the given string is incomplete (because a partial
77        match is preferred over a full match). For this reason, these items now
78        give a partial match in this situation. [Aside: previously, the one case
79        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
80        match rather than a full match, which was wrong by the old rules, but is
81        now correct.]
82    
83    6.  There was a bug in the handling of #-introduced comments, recognized when
84        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
85        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
86        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
87        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
88        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
89        places in pcre_compile().
90    
91    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
92        comments when looking ahead for named forward references to subpatterns,
93        the only newline sequence it recognized was NL. It now handles newlines
94        according to the set newline convention.
95    
96    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
97        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
98        cater for a lack of strerror(). These oversights have been fixed.
99    
100    9.  Added --match-limit and --recursion-limit to pcregrep.
101    
102    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
103    
104    11. When the -o option was used, pcregrep was setting a return code of 1, even
105        when matches were found, and --line-buffered was not being honoured.
106    
107    12. Added an optional parentheses number to the -o and --only-matching options
108        of pcregrep.
109    
110    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
111        can match an empty string. The code to do it in pcretest and pcredemo
112        needed fixing:
113    
114        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
115            only one byte after an empty string match just before CRLF (this case
116            just got forgotten; "any" and "anycrlf" were OK).
117    
118        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
119            mode when an empty string match preceded an ASCII character followed by
120            a non-ASCII character. (The code for advancing by one character rather
121            than one byte was nonsense.)
122    
123        (c) The pcredemo.c sample program did not have any code at all to handle
124            the cases when CRLF is a valid newline sequence.
125    
126    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
127        as a starting offset was within the subject string. There is now a new
128        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
129        negative or greater than the length of the string. In order to test this,
130        pcretest is extended to allow the setting of negative starting offsets.
131    
132    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
133        starting offset points to the beginning of a UTF-8 character was
134        unnecessarily clumsy. I tidied it up.
135    
136    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
137        bad UTF-8 sequence and one that is incomplete when using PCRE_PARTIAL_HARD.
138    
139    17. Nobody had reported that the --include_dir option, which was added in
140        release 7.7 should have been called --include-dir (hyphen, not underscore)
141        for compatibility with GNU grep. I have changed it to --include-dir, but
142        left --include_dir as an undocumented synonym, and the same for
143        --exclude-dir, though that is not available in GNU grep, at least as of
144        release 2.5.4.
145    
146    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
147        characters from a string of bytes) have been redefined so as not to use
148        loops, in order to improve performance in some environments. At the same
149        time, I abstracted some of the common code into auxiliary macros to save
150        repetition (this should not affect the compiled code).
151    
152    19. If \c was followed by a multibyte UTF-8 character, bad things happened. A
153        compile-time error is now given if \c is not followed by an ASCII
154        character, that is, a byte less than 128. (In EBCDIC mode, the code is
155        different, and any byte value is allowed.)
156    
157    20. Recognize (*NO_START_OPT) at the start of a pattern to set the PCRE_NO_
158        START_OPTIMIZE option, which is now allowed at compile time - but just
159        passed through to pcre_exec() or pcre_dfa_exec(). This makes it available
160        to pcregrep and other applications that have no direct access to PCRE
161        options. The new /Y option in pcretest sets this option when calling
162        pcre_compile().
163    
164    21. Change 18 of release 8.01 broke the use of named subpatterns for recursive
165        back references. Groups containing recursive back references were forced to
166        be atomic by that change, but in the case of named groups, the amount of
167        memory required was incorrectly computed, leading to "Failed: internal
168        error: code overflow". This has been fixed.
169    
170    22. Some patches to pcre_stringpiece.h, pcre_stringpiece_unittest.cc, and
171        pcretest.c, to avoid build problems in some Borland environments.
172    
173    
174    Version 8.10 25-Jun-2010
175    ------------------------
176    
177    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
178        THEN.
179    
180    2.  (*ACCEPT) was not working when inside an atomic group.
181    
182    3.  Inside a character class, \B is treated as a literal by default, but
183        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
184        causes the error). The code is unchanged, but I tidied the documentation.
185    
186    4.  Inside a character class, PCRE always treated \R and \X as literals,
187        whereas Perl faults them if its -w option is set. I have changed PCRE so
188        that it faults them when PCRE_EXTRA is set.
189    
190    5.  Added support for \N, which always matches any character other than
191        newline. (It is the same as "." when PCRE_DOTALL is not set.)
192    
193    6.  When compiling pcregrep with newer versions of gcc which may have
194        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
195        declared with attribute warn_unused_result" were given. Just casting the
196        result to (void) does not stop the warnings; a more elaborate fudge is
197        needed. I've used a macro to implement this.
198    
199    7.  Minor change to pcretest.c to avoid a compiler warning.
200    
201    8.  Added four artifical Unicode properties to help with an option to make
202        \s etc use properties (see next item). The new properties are: Xan
203        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
204    
205    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
206        use Unicode properties. (*UCP) at the start of a pattern can be used to set
207        this option. Modified pcretest to add /W to test this facility. Added
208        REG_UCP to make it available via the POSIX interface.
209    
210    10. Added --line-buffered to pcregrep.
211    
212    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
213        studied, and the match started with a letter with a code point greater than
214        127 whose first byte was different to the first byte of the other case of
215        the letter, the other case of this starting letter was not recognized
216        (#976).
217    
218    12. If a pattern that was studied started with a repeated Unicode property
219        test, for example, \p{Nd}+, there was the theoretical possibility of
220        setting up an incorrect bitmap of starting bytes, but fortunately it could
221        not have actually happened in practice until change 8 above was made (it
222        added property types that matched character-matching opcodes).
223    
224    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
225        possible starting bytes for non-anchored patterns.
226    
227    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
228        \R, and also a number of cases that involve Unicode properties, both
229        explicit and implicit when PCRE_UCP is set.
230    
231    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
232        input, it could crash or give wrong results if characters with values
233        greater than 0xc0 were present in the subject string. (Detail: it assumed
234        UTF-8 input when processing these items.)
235    
236    16. Added a lot of (int) casts to avoid compiler warnings in systems where
237        size_t is 64-bit (#991).
238    
239    17. Added a check for running out of memory when PCRE is compiled with
240        --disable-stack-for-recursion (#990).
241    
242    18. If the last data line in a file for pcretest does not have a newline on
243        the end, a newline was missing in the output.
244    
245    19. The default pcre_chartables.c file recognizes only ASCII characters (values
246        less than 128) in its various bitmaps. However, there is a facility for
247        generating tables according to the current locale when PCRE is compiled. It
248        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
249        characters, are recognized by isspace() and therefore were getting set in
250        these tables, and indeed these tables seem to approximate to ISO 8859. This
251        caused a problem in UTF-8 mode when pcre_study() was used to create a list
252        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
253        which of course cannot start UTF-8 characters. I have changed the code so
254        that only real ASCII characters (less than 128) and the correct starting
255        bytes for UTF-8 encodings are set for characters greater than 127 when in
256        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
257        altogether.)
258    
259    20. Added the /T option to pcretest so as to be able to run tests with non-
260        standard character tables, thus making it possible to include the tests
261        used for 19 above in the standard set of tests.
262    
263    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
264        reference to a subpattern the other side of a comment that contains an
265        opening parenthesis caused either an internal compiling error, or a
266        reference to the wrong subpattern.
267    
268    
269    Version 8.02 19-Mar-2010
270    ------------------------
271    
272    1.  The Unicode data tables have been updated to Unicode 5.2.0.
273    
274    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
275        configured.
276    
277    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
278        original author of that file, following a query about its status.
279    
280    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
281        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
282    
283    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
284        quantifier applied to a forward-referencing subroutine call, could compile
285        incorrect code or give the error "internal error: previously-checked
286        referenced subpattern not found".
287    
288    6.  Both MS Visual Studio and Symbian OS have problems with initializing
289        variables to point to external functions. For these systems, therefore,
290        pcre_malloc etc. are now initialized to local functions that call the
291        relevant global functions.
292    
293    7.  There were two entries missing in the vectors called coptable and poptable
294        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
295        I've fixed the data, and added a kludgy way of testing at compile time that
296        the lengths are correct (equal to the number of opcodes).
297    
298    8.  Following on from 7, I added a similar kludge to check the length of the
299        eint vector in pcreposix.c.
300    
301    9.  Error texts for pcre_compile() are held as one long string to avoid too
302        much relocation at load time. To find a text, the string is searched,
303        counting zeros. There was no check for running off the end of the string,
304        which could happen if a new error number was added without updating the
305        string.
306    
307    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
308    
309    11. \K was not working if it appeared in an atomic group or in a group that
310        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
311        \K is "not well defined" if used in an assertion. PCRE now accepts it if
312        the assertion is positive, but not if it is negative.
313    
314    12. Change 11 fortuitously reduced the size of the stack frame used in the
315        "match()" function of pcre_exec.c by one pointer. Forthcoming
316        implementation of support for (*MARK) will need an extra pointer on the
317        stack; I have reserved it now, so that the stack frame size does not
318        decrease.
319    
320    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
321        item in branch that calls a recursion is a subroutine call - as in the
322        second branch in the above example - was incorrectly given the compile-
323        time error "recursive call could loop indefinitely" because pcre_compile()
324        was not correctly checking the subroutine for matching a non-empty string.
325    
326    14. The checks for overrunning compiling workspace could trigger after an
327        overrun had occurred. This is a "should never occur" error, but it can be
328        triggered by pathological patterns such as hundreds of nested parentheses.
329        The checks now trigger 100 bytes before the end of the workspace.
330    
331    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
332    
333    
334    Version 8.01 19-Jan-2010
335    ------------------------
336    
337    1.  If a pattern contained a conditional subpattern with only one branch (in
338        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
339        computed the wrong minimum data length (which is of course zero for such
340        subpatterns). This could cause incorrect "no match" results.
341    
342    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
343        the pattern is reset in the first branch, pcre_compile() failed with
344        "internal error: code overflow at offset...". This happened only when
345        the reset was to the original external option setting. (An optimization
346        abstracts leading options settings into an external setting, which was the
347        cause of this.)
348    
349    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
350        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
351        assertion pattern did not match (meaning that the assertion was true), it
352        was incorrectly treated as false if the SKIP had been reached during the
353        matching. This also applied to assertions used as conditions.
354    
355    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
356        assertion subpattern, including such a pattern used as a condition,
357        unpredictable results occurred, instead of the error return
358        PCRE_ERROR_DFA_UITEM.
359    
360    5.  The C++ GlobalReplace function was not working like Perl for the special
361        situation when an empty string is matched. It now does the fancy magic
362        stuff that is necessary.
363    
364    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
365        removed. (These were left over from very, very early versions of PCRE.)
366    
367    7.  Some cosmetic changes to the code to make life easier when compiling it
368        as part of something else:
369    
370        (a) Change DEBUG to PCRE_DEBUG.
371    
372        (b) In pcre_compile(), rename the member of the "branch_chain" structure
373            called "current" as "current_branch", to prevent a collision with the
374            Linux macro when compiled as a kernel module.
375    
376        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
377            prevent a collision with the Linux macro when compiled as a kernel
378            module.
379    
380    8.  In pcre_compile() there are some checks for integer overflows that used to
381        cast potentially large values to (double). This has been changed to that
382        when building, a check for int64_t is made, and if it is found, it is used
383        instead, thus avoiding the use of floating point arithmetic. (There is no
384        other use of FP in PCRE.) If int64_t is not found, the fallback is to
385        double.
386    
387    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
388        2005 (difference between two addresses compared to an unsigned value).
389    
390    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
391        custom one, because of the following reported problem in Windows:
392    
393          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
394              under Win32.
395          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
396              therefore missing the function definition.
397          - The compiler thus generates a "C" signature for the test function.
398          - The linker fails to find the "C" function.
399          - PCRE fails to configure if asked to do so against libbz2.
400    
401    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
402        messages were output:
403    
404          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
405          rerunning libtoolize, to keep the correct libtool macros in-tree.
406          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
407    
408        I have done both of these things.
409    
410    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
411        most of the time, it *can* run out if it is given a pattern that contains a
412        runaway infinite recursion. I updated the discussion in the pcrestack man
413        page.
414    
415    13. Now that we have gone to the x.xx style of version numbers, the minor
416        version may start with zero. Using 08 or 09 is a bad idea because users
417        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
418        interpreted as invalid octal numbers. I've updated the previous comment in
419        configure.ac, and also added a check that gives an error if 08 or 09 are
420        used.
421    
422    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
423        causing partial matching to fail when the end of the subject matched \W
424        in a UTF-8 pattern where \W was quantified with a minimum of 3.
425    
426    15. There were some discrepancies between the declarations in pcre_internal.h
427        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
428        their definitions. The declarations used "const uschar *" and the
429        definitions used USPTR. Even though USPTR is normally defined as "const
430        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
431        reported that: "This difference in casting confuses some C++ compilers, for
432        example, SunCC recognizes above declarations as different functions and
433        generates broken code for hbpcre." I have changed the declarations to use
434        USPTR.
435    
436    16. GNU libtool is named differently on some systems. The autogen.sh script now
437        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
438        (FreeBSD).
439    
440    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
441        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
442        comment: "Figure out how to create a longlong from a string: strtoll and
443        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
444        instance, but it only takes 2 args instead of 3!"
445    
446    18. A subtle bug concerned with back references has been fixed by a change of
447        specification, with a corresponding code fix. A pattern such as
448        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
449        refers, was giving matches when it shouldn't. For example, xa=xaaa would
450        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
451        same bug. Such groups have to be quantified to be useful, or contained
452        inside another quantified group. (If there's no repetition, the reference
453        can never match.) The problem arises because, having left the group and
454        moved on to the rest of the pattern, a later failure that backtracks into
455        the group uses the captured value from the final iteration of the group
456        rather than the correct earlier one. I have fixed this in PCRE by forcing
457        any group that contains a reference to itself to be an atomic group; that
458        is, there cannot be any backtracking into it once it has completed. This is
459        similar to recursive and subroutine calls.
460    
461    
462    Version 8.00 19-Oct-09
463  ----------------------  ----------------------
464    
465  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
466      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
467      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
468      error.      error.
469    
470  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,
471      "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
472      in a Windows environment.      in a Windows environment.
473    
474    3.  The pcregrep --count option prints the count for each file even when it is
475        zero, as does GNU grep. However, pcregrep was also printing all files when
476        --files-with-matches was added. Now, when both options are given, it prints
477        counts only for those files that have at least one match. (GNU grep just
478        prints the file name in this circumstance, but including the count seems
479        more useful - otherwise, why use --count?) Also ensured that the
480        combination -clh just lists non-zero counts, with no names.
481    
482    4.  The long form of the pcregrep -F option was incorrectly implemented as
483        --fixed_strings instead of --fixed-strings. This is an incompatible change,
484        but it seems right to fix it, and I didn't think it was worth preserving
485        the old behaviour.
486    
487    5.  The command line items --regex=pattern and --regexp=pattern were not
488        recognized by pcregrep, which required --regex pattern or --regexp pattern
489        (with a space rather than an '='). The man page documented the '=' forms,
490        which are compatible with GNU grep; these now work.
491    
492    6.  No libpcreposix.pc file was created for pkg-config; there was just
493        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
494    
495    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
496        when UCP support is not needed, by modifying the Python script that
497        generates it from Unicode data files. This should not matter if the module
498        is correctly used as a library, but I received one complaint about 50K of
499        unwanted data. My guess is that the person linked everything into his
500        program rather than using a library. Anyway, it does no harm.
501    
502    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
503        was a minimum greater than 1 for a wide character in a possessive
504        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
505        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
506        character. Chaos in the form of incorrect output or a compiling loop could
507        result.
508    
509    9.  The restrictions on what a pattern can contain when partial matching is
510        requested for pcre_exec() have been removed. All patterns can now be
511        partially matched by this function. In addition, if there are at least two
512        slots in the offset vector, the offset of the earliest inspected character
513        for the match and the offset of the end of the subject are set in them when
514        PCRE_ERROR_PARTIAL is returned.
515    
516    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
517        synonymous with PCRE_PARTIAL, for backwards compatibility, and
518        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
519        and may be more useful for multi-segment matching.
520    
521    11. Partial matching with pcre_exec() is now more intuitive. A partial match
522        used to be given if ever the end of the subject was reached; now it is
523        given only if matching could not proceed because another character was
524        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
525        string "Z", which now yields "no match" instead of "partial match". In the
526        case of pcre_dfa_exec(), "no match" is given if every matching path for the
527        final character ended with (*FAIL).
528    
529    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
530        if the pattern had a "must contain" character that was already found in the
531        earlier partial match, unless partial matching was again requested. For
532        example, with the pattern /dog.(body)?/, the "must contain" character is
533        "g". If the first part-match was for the string "dog", restarting with
534        "sbody" failed. This bug has been fixed.
535    
536    13. The string returned by pcre_dfa_exec() after a partial match has been
537        changed so that it starts at the first inspected character rather than the
538        first character of the match. This makes a difference only if the pattern
539        starts with a lookbehind assertion or \b or \B (\K is not supported by
540        pcre_dfa_exec()). It's an incompatible change, but it makes the two
541        matching functions compatible, and I think it's the right thing to do.
542    
543    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
544        so that the demonstration program is easily available in environments where
545        PCRE has not been installed from source.
546    
547    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
548        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
549        library.
550    
551    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
552        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
553        is not the first non-POSIX option to be added. Clearly some people find
554        these options useful.
555    
556    17. If a caller to the POSIX matching function regexec() passes a non-zero
557        value for nmatch with a NULL value for pmatch, the value of
558        nmatch is forced to zero.
559    
560    18. RunGrepTest did not have a test for the availability of the -u option of
561        the diff command, as RunTest does. It now checks in the same way as
562        RunTest, and also checks for the -b option.
563    
564    19. If an odd number of negated classes containing just a single character
565        interposed, within parentheses, between a forward reference to a named
566        subpattern and the definition of the subpattern, compilation crashed with
567        an internal error, complaining that it could not find the referenced
568        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
569        [The bug was that it was starting one character too far in when skipping
570        over the character class, thus treating the ] as data rather than
571        terminating the class. This meant it could skip too much.]
572    
573    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
574        /g option in pcretest when the pattern contains \K, which makes it possible
575        to have an empty string match not at the start, even when the pattern is
576        anchored. Updated pcretest and pcredemo to use this option.
577    
578    21. If the maximum number of capturing subpatterns in a recursion was greater
579        than the maximum at the outer level, the higher number was returned, but
580        with unset values at the outer level. The correct (outer level) value is
581        now given.
582    
583    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
584        PCRE did not set those parentheses (unlike Perl). I have now found a way to
585        make it do so. The string so far is captured, making this feature
586        compatible with Perl.
587    
588    23. The tests have been re-organized, adding tests 11 and 12, to make it
589        possible to check the Perl 5.10 features against Perl 5.10.
590    
591    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
592        pattern matches a fixed length string. PCRE did not allow this; now it
593        does. Neither allows recursion.
594    
595    25. I finally figured out how to implement a request to provide the minimum
596        length of subject string that was needed in order to match a given pattern.
597        (It was back references and recursion that I had previously got hung up
598        on.) This code has now been added to pcre_study(); it finds a lower bound
599        to the length of subject needed. It is not necessarily the greatest lower
600        bound, but using it to avoid searching strings that are too short does give
601        some useful speed-ups. The value is available to calling programs via
602        pcre_fullinfo().
603    
604    26. While implementing 25, I discovered to my embarrassment that pcretest had
605        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
606        study optimizations had never been tested with that matching function.
607        Oops. What is worse, even when it was passed study data, there was a bug in
608        pcre_dfa_exec() that meant it never actually used it. Double oops. There
609        were also very few tests of studied patterns with pcre_dfa_exec().
610    
611    27. If (?| is used to create subpatterns with duplicate numbers, they are now
612        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
613        on the other side of the coin, they are no longer allowed to have different
614        names, because these cannot be distinguished in PCRE, and this has caused
615        confusion. (This is a difference from Perl.)
616    
617    28. When duplicate subpattern names are present (necessarily with different
618        numbers, as required by 27 above), and a test is made by name in a
619        conditional pattern, either for a subpattern having been matched, or for
620        recursion in such a pattern, all the associated numbered subpatterns are
621        tested, and the overall condition is true if the condition is true for any
622        one of them. This is the way Perl works, and is also more like the way
623        testing by number works.
624    
625    
626  Version 7.9 11-Apr-09  Version 7.9 11-Apr-09

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