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

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