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revision 157 by ph10, Tue May 1 09:19:56 2007 UTC revision 566 by ph10, Wed Nov 3 18:32:55 2010 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 7.2 01-May-07  Version 8.11 10-Oct-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    
87    Version 8.10 25-Jun-2010
88    ------------------------
89    
90    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
91        THEN.
92    
93    2.  (*ACCEPT) was not working when inside an atomic group.
94    
95    3.  Inside a character class, \B is treated as a literal by default, but
96        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
97        causes the error). The code is unchanged, but I tidied the documentation.
98    
99    4.  Inside a character class, PCRE always treated \R and \X as literals,
100        whereas Perl faults them if its -w option is set. I have changed PCRE so
101        that it faults them when PCRE_EXTRA is set.
102    
103    5.  Added support for \N, which always matches any character other than
104        newline. (It is the same as "." when PCRE_DOTALL is not set.)
105    
106    6.  When compiling pcregrep with newer versions of gcc which may have
107        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
108        declared with attribute warn_unused_result" were given. Just casting the
109        result to (void) does not stop the warnings; a more elaborate fudge is
110        needed. I've used a macro to implement this.
111    
112    7.  Minor change to pcretest.c to avoid a compiler warning.
113    
114    8.  Added four artifical Unicode properties to help with an option to make
115        \s etc use properties (see next item). The new properties are: Xan
116        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
117    
118    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
119        use Unicode properties. (*UCP) at the start of a pattern can be used to set
120        this option. Modified pcretest to add /W to test this facility. Added
121        REG_UCP to make it available via the POSIX interface.
122    
123    10. Added --line-buffered to pcregrep.
124    
125    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
126        studied, and the match started with a letter with a code point greater than
127        127 whose first byte was different to the first byte of the other case of
128        the letter, the other case of this starting letter was not recognized
129        (#976).
130    
131    12. If a pattern that was studied started with a repeated Unicode property
132        test, for example, \p{Nd}+, there was the theoretical possibility of
133        setting up an incorrect bitmap of starting bytes, but fortunately it could
134        not have actually happened in practice until change 8 above was made (it
135        added property types that matched character-matching opcodes).
136    
137    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
138        possible starting bytes for non-anchored patterns.
139    
140    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
141        \R, and also a number of cases that involve Unicode properties, both
142        explicit and implicit when PCRE_UCP is set.
143    
144    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
145        input, it could crash or give wrong results if characters with values
146        greater than 0xc0 were present in the subject string. (Detail: it assumed
147        UTF-8 input when processing these items.)
148    
149    16. Added a lot of (int) casts to avoid compiler warnings in systems where
150        size_t is 64-bit (#991).
151    
152    17. Added a check for running out of memory when PCRE is compiled with
153        --disable-stack-for-recursion (#990).
154    
155    18. If the last data line in a file for pcretest does not have a newline on
156        the end, a newline was missing in the output.
157    
158    19. The default pcre_chartables.c file recognizes only ASCII characters (values
159        less than 128) in its various bitmaps. However, there is a facility for
160        generating tables according to the current locale when PCRE is compiled. It
161        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
162        characters, are recognized by isspace() and therefore were getting set in
163        these tables, and indeed these tables seem to approximate to ISO 8859. This
164        caused a problem in UTF-8 mode when pcre_study() was used to create a list
165        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
166        which of course cannot start UTF-8 characters. I have changed the code so
167        that only real ASCII characters (less than 128) and the correct starting
168        bytes for UTF-8 encodings are set for characters greater than 127 when in
169        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
170        altogether.)
171    
172    20. Added the /T option to pcretest so as to be able to run tests with non-
173        standard character tables, thus making it possible to include the tests
174        used for 19 above in the standard set of tests.
175    
176    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
177        reference to a subpattern the other side of a comment that contains an
178        opening parenthesis caused either an internal compiling error, or a
179        reference to the wrong subpattern.
180    
181    
182    Version 8.02 19-Mar-2010
183    ------------------------
184    
185    1.  The Unicode data tables have been updated to Unicode 5.2.0.
186    
187    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
188        configured.
189    
190    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
191        original author of that file, following a query about its status.
192    
193    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
194        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
195    
196    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
197        quantifier applied to a forward-referencing subroutine call, could compile
198        incorrect code or give the error "internal error: previously-checked
199        referenced subpattern not found".
200    
201    6.  Both MS Visual Studio and Symbian OS have problems with initializing
202        variables to point to external functions. For these systems, therefore,
203        pcre_malloc etc. are now initialized to local functions that call the
204        relevant global functions.
205    
206    7.  There were two entries missing in the vectors called coptable and poptable
207        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
208        I've fixed the data, and added a kludgy way of testing at compile time that
209        the lengths are correct (equal to the number of opcodes).
210    
211    8.  Following on from 7, I added a similar kludge to check the length of the
212        eint vector in pcreposix.c.
213    
214    9.  Error texts for pcre_compile() are held as one long string to avoid too
215        much relocation at load time. To find a text, the string is searched,
216        counting zeros. There was no check for running off the end of the string,
217        which could happen if a new error number was added without updating the
218        string.
219    
220    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
221    
222    11. \K was not working if it appeared in an atomic group or in a group that
223        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
224        \K is "not well defined" if used in an assertion. PCRE now accepts it if
225        the assertion is positive, but not if it is negative.
226    
227    12. Change 11 fortuitously reduced the size of the stack frame used in the
228        "match()" function of pcre_exec.c by one pointer. Forthcoming
229        implementation of support for (*MARK) will need an extra pointer on the
230        stack; I have reserved it now, so that the stack frame size does not
231        decrease.
232    
233    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
234        item in branch that calls a recursion is a subroutine call - as in the
235        second branch in the above example - was incorrectly given the compile-
236        time error "recursive call could loop indefinitely" because pcre_compile()
237        was not correctly checking the subroutine for matching a non-empty string.
238    
239    14. The checks for overrunning compiling workspace could trigger after an
240        overrun had occurred. This is a "should never occur" error, but it can be
241        triggered by pathological patterns such as hundreds of nested parentheses.
242        The checks now trigger 100 bytes before the end of the workspace.
243    
244    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
245    
246    
247    Version 8.01 19-Jan-2010
248    ------------------------
249    
250    1.  If a pattern contained a conditional subpattern with only one branch (in
251        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
252        computed the wrong minimum data length (which is of course zero for such
253        subpatterns). This could cause incorrect "no match" results.
254    
255    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
256        the pattern is reset in the first branch, pcre_compile() failed with
257        "internal error: code overflow at offset...". This happened only when
258        the reset was to the original external option setting. (An optimization
259        abstracts leading options settings into an external setting, which was the
260        cause of this.)
261    
262    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
263        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
264        assertion pattern did not match (meaning that the assertion was true), it
265        was incorrectly treated as false if the SKIP had been reached during the
266        matching. This also applied to assertions used as conditions.
267    
268    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
269        assertion subpattern, including such a pattern used as a condition,
270        unpredictable results occurred, instead of the error return
271        PCRE_ERROR_DFA_UITEM.
272    
273    5.  The C++ GlobalReplace function was not working like Perl for the special
274        situation when an empty string is matched. It now does the fancy magic
275        stuff that is necessary.
276    
277    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
278        removed. (These were left over from very, very early versions of PCRE.)
279    
280    7.  Some cosmetic changes to the code to make life easier when compiling it
281        as part of something else:
282    
283        (a) Change DEBUG to PCRE_DEBUG.
284    
285        (b) In pcre_compile(), rename the member of the "branch_chain" structure
286            called "current" as "current_branch", to prevent a collision with the
287            Linux macro when compiled as a kernel module.
288    
289        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
290            prevent a collision with the Linux macro when compiled as a kernel
291            module.
292    
293    8.  In pcre_compile() there are some checks for integer overflows that used to
294        cast potentially large values to (double). This has been changed to that
295        when building, a check for int64_t is made, and if it is found, it is used
296        instead, thus avoiding the use of floating point arithmetic. (There is no
297        other use of FP in PCRE.) If int64_t is not found, the fallback is to
298        double.
299    
300    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
301        2005 (difference between two addresses compared to an unsigned value).
302    
303    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
304        custom one, because of the following reported problem in Windows:
305    
306          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
307              under Win32.
308          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
309              therefore missing the function definition.
310          - The compiler thus generates a "C" signature for the test function.
311          - The linker fails to find the "C" function.
312          - PCRE fails to configure if asked to do so against libbz2.
313    
314    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
315        messages were output:
316    
317          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
318          rerunning libtoolize, to keep the correct libtool macros in-tree.
319          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
320    
321        I have done both of these things.
322    
323    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
324        most of the time, it *can* run out if it is given a pattern that contains a
325        runaway infinite recursion. I updated the discussion in the pcrestack man
326        page.
327    
328    13. Now that we have gone to the x.xx style of version numbers, the minor
329        version may start with zero. Using 08 or 09 is a bad idea because users
330        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
331        interpreted as invalid octal numbers. I've updated the previous comment in
332        configure.ac, and also added a check that gives an error if 08 or 09 are
333        used.
334    
335    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
336        causing partial matching to fail when the end of the subject matched \W
337        in a UTF-8 pattern where \W was quantified with a minimum of 3.
338    
339    15. There were some discrepancies between the declarations in pcre_internal.h
340        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
341        their definitions. The declarations used "const uschar *" and the
342        definitions used USPTR. Even though USPTR is normally defined as "const
343        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
344        reported that: "This difference in casting confuses some C++ compilers, for
345        example, SunCC recognizes above declarations as different functions and
346        generates broken code for hbpcre." I have changed the declarations to use
347        USPTR.
348    
349    16. GNU libtool is named differently on some systems. The autogen.sh script now
350        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
351        (FreeBSD).
352    
353    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
354        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
355        comment: "Figure out how to create a longlong from a string: strtoll and
356        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
357        instance, but it only takes 2 args instead of 3!"
358    
359    18. A subtle bug concerned with back references has been fixed by a change of
360        specification, with a corresponding code fix. A pattern such as
361        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
362        refers, was giving matches when it shouldn't. For example, xa=xaaa would
363        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
364        same bug. Such groups have to be quantified to be useful, or contained
365        inside another quantified group. (If there's no repetition, the reference
366        can never match.) The problem arises because, having left the group and
367        moved on to the rest of the pattern, a later failure that backtracks into
368        the group uses the captured value from the final iteration of the group
369        rather than the correct earlier one. I have fixed this in PCRE by forcing
370        any group that contains a reference to itself to be an atomic group; that
371        is, there cannot be any backtracking into it once it has completed. This is
372        similar to recursive and subroutine calls.
373    
374    
375    Version 8.00 19-Oct-09
376    ----------------------
377    
378    1.  The table for translating pcre_compile() error codes into POSIX error codes
379        was out-of-date, and there was no check on the pcre_compile() error code
380        being within the table. This could lead to an OK return being given in
381        error.
382    
383    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
384        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
385        in a Windows environment.
386    
387    3.  The pcregrep --count option prints the count for each file even when it is
388        zero, as does GNU grep. However, pcregrep was also printing all files when
389        --files-with-matches was added. Now, when both options are given, it prints
390        counts only for those files that have at least one match. (GNU grep just
391        prints the file name in this circumstance, but including the count seems
392        more useful - otherwise, why use --count?) Also ensured that the
393        combination -clh just lists non-zero counts, with no names.
394    
395    4.  The long form of the pcregrep -F option was incorrectly implemented as
396        --fixed_strings instead of --fixed-strings. This is an incompatible change,
397        but it seems right to fix it, and I didn't think it was worth preserving
398        the old behaviour.
399    
400    5.  The command line items --regex=pattern and --regexp=pattern were not
401        recognized by pcregrep, which required --regex pattern or --regexp pattern
402        (with a space rather than an '='). The man page documented the '=' forms,
403        which are compatible with GNU grep; these now work.
404    
405    6.  No libpcreposix.pc file was created for pkg-config; there was just
406        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
407    
408    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
409        when UCP support is not needed, by modifying the Python script that
410        generates it from Unicode data files. This should not matter if the module
411        is correctly used as a library, but I received one complaint about 50K of
412        unwanted data. My guess is that the person linked everything into his
413        program rather than using a library. Anyway, it does no harm.
414    
415    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
416        was a minimum greater than 1 for a wide character in a possessive
417        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
418        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
419        character. Chaos in the form of incorrect output or a compiling loop could
420        result.
421    
422    9.  The restrictions on what a pattern can contain when partial matching is
423        requested for pcre_exec() have been removed. All patterns can now be
424        partially matched by this function. In addition, if there are at least two
425        slots in the offset vector, the offset of the earliest inspected character
426        for the match and the offset of the end of the subject are set in them when
427        PCRE_ERROR_PARTIAL is returned.
428    
429    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
430        synonymous with PCRE_PARTIAL, for backwards compatibility, and
431        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
432        and may be more useful for multi-segment matching.
433    
434    11. Partial matching with pcre_exec() is now more intuitive. A partial match
435        used to be given if ever the end of the subject was reached; now it is
436        given only if matching could not proceed because another character was
437        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
438        string "Z", which now yields "no match" instead of "partial match". In the
439        case of pcre_dfa_exec(), "no match" is given if every matching path for the
440        final character ended with (*FAIL).
441    
442    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
443        if the pattern had a "must contain" character that was already found in the
444        earlier partial match, unless partial matching was again requested. For
445        example, with the pattern /dog.(body)?/, the "must contain" character is
446        "g". If the first part-match was for the string "dog", restarting with
447        "sbody" failed. This bug has been fixed.
448    
449    13. The string returned by pcre_dfa_exec() after a partial match has been
450        changed so that it starts at the first inspected character rather than the
451        first character of the match. This makes a difference only if the pattern
452        starts with a lookbehind assertion or \b or \B (\K is not supported by
453        pcre_dfa_exec()). It's an incompatible change, but it makes the two
454        matching functions compatible, and I think it's the right thing to do.
455    
456    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
457        so that the demonstration program is easily available in environments where
458        PCRE has not been installed from source.
459    
460    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
461        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
462        library.
463    
464    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
465        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
466        is not the first non-POSIX option to be added. Clearly some people find
467        these options useful.
468    
469    17. If a caller to the POSIX matching function regexec() passes a non-zero
470        value for nmatch with a NULL value for pmatch, the value of
471        nmatch is forced to zero.
472    
473    18. RunGrepTest did not have a test for the availability of the -u option of
474        the diff command, as RunTest does. It now checks in the same way as
475        RunTest, and also checks for the -b option.
476    
477    19. If an odd number of negated classes containing just a single character
478        interposed, within parentheses, between a forward reference to a named
479        subpattern and the definition of the subpattern, compilation crashed with
480        an internal error, complaining that it could not find the referenced
481        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
482        [The bug was that it was starting one character too far in when skipping
483        over the character class, thus treating the ] as data rather than
484        terminating the class. This meant it could skip too much.]
485    
486    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
487        /g option in pcretest when the pattern contains \K, which makes it possible
488        to have an empty string match not at the start, even when the pattern is
489        anchored. Updated pcretest and pcredemo to use this option.
490    
491    21. If the maximum number of capturing subpatterns in a recursion was greater
492        than the maximum at the outer level, the higher number was returned, but
493        with unset values at the outer level. The correct (outer level) value is
494        now given.
495    
496    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
497        PCRE did not set those parentheses (unlike Perl). I have now found a way to
498        make it do so. The string so far is captured, making this feature
499        compatible with Perl.
500    
501    23. The tests have been re-organized, adding tests 11 and 12, to make it
502        possible to check the Perl 5.10 features against Perl 5.10.
503    
504    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
505        pattern matches a fixed length string. PCRE did not allow this; now it
506        does. Neither allows recursion.
507    
508    25. I finally figured out how to implement a request to provide the minimum
509        length of subject string that was needed in order to match a given pattern.
510        (It was back references and recursion that I had previously got hung up
511        on.) This code has now been added to pcre_study(); it finds a lower bound
512        to the length of subject needed. It is not necessarily the greatest lower
513        bound, but using it to avoid searching strings that are too short does give
514        some useful speed-ups. The value is available to calling programs via
515        pcre_fullinfo().
516    
517    26. While implementing 25, I discovered to my embarrassment that pcretest had
518        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
519        study optimizations had never been tested with that matching function.
520        Oops. What is worse, even when it was passed study data, there was a bug in
521        pcre_dfa_exec() that meant it never actually used it. Double oops. There
522        were also very few tests of studied patterns with pcre_dfa_exec().
523    
524    27. If (?| is used to create subpatterns with duplicate numbers, they are now
525        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
526        on the other side of the coin, they are no longer allowed to have different
527        names, because these cannot be distinguished in PCRE, and this has caused
528        confusion. (This is a difference from Perl.)
529    
530    28. When duplicate subpattern names are present (necessarily with different
531        numbers, as required by 27 above), and a test is made by name in a
532        conditional pattern, either for a subpattern having been matched, or for
533        recursion in such a pattern, all the associated numbered subpatterns are
534        tested, and the overall condition is true if the condition is true for any
535        one of them. This is the way Perl works, and is also more like the way
536        testing by number works.
537    
538    
539    Version 7.9 11-Apr-09
540    ---------------------
541    
542    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
543        (pcretest), all targets were linked against these libraries. This included
544        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
545        libraries. This caused unwanted dependencies to be created. This problem
546        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
547        pcretest is linked with readline.
548    
549    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
550        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
551        moved outside it again, because FALSE and TRUE are already defined in AIX,
552        but BOOL is not.
553    
554    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
555        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
556    
557    4.  The pcregrep documentation said spaces were inserted as well as colons (or
558        hyphens) following file names and line numbers when outputting matching
559        lines. This is not true; no spaces are inserted. I have also clarified the
560        wording for the --colour (or --color) option.
561    
562    5.  In pcregrep, when --colour was used with -o, the list of matching strings
563        was not coloured; this is different to GNU grep, so I have changed it to be
564        the same.
565    
566    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
567        each matching line was coloured. Now it goes on to look for further matches
568        of any of the test patterns, which is the same behaviour as GNU grep.
569    
570    7.  A pattern that could match an empty string could cause pcregrep to loop; it
571        doesn't make sense to accept an empty string match in pcregrep, so I have
572        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
573        seems to be how GNU grep behaves.
574    
575    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
576        start or after a newline", because the conditional assertion was not being
577        correctly handled. The rule now is that both the assertion and what follows
578        in the first alternative must satisfy the test.
579    
580    9.  If auto-callout was enabled in a pattern with a conditional group whose
581        condition was an assertion, PCRE could crash during matching, both with
582        pcre_exec() and pcre_dfa_exec().
583    
584    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
585        used for matching.
586    
587    11. Unicode property support in character classes was not working for
588        characters (bytes) greater than 127 when not in UTF-8 mode.
589    
590    12. Added the -M command line option to pcretest.
591    
592    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
593    
594    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
595    
596    16. Added comments and documentation about mis-use of no_arg in the C++
597        wrapper.
598    
599    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
600        from Martin Jerabek that uses macro names for all relevant character and
601        string constants.
602    
603    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
604        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
605        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
606        these, but not everybody uses configure.
607    
608    19. A conditional group that had only one branch was not being correctly
609        recognized as an item that could match an empty string. This meant that an
610        enclosing group might also not be so recognized, causing infinite looping
611        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
612        with the subject "ab", where knowledge that the repeated group can match
613        nothing is needed in order to break the loop.
614    
615    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
616        exec(), but without supplying a callout function, matching went wrong.
617    
618    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
619        leak if the size of the offset vector was greater than 30. When the vector
620        is smaller, the saved offsets during recursion go onto a local stack
621        vector, but for larger vectors malloc() is used. It was failing to free
622        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
623        error, in fact).
624    
625    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
626        heapframe that is used only when UTF-8 support is enabled. This caused no
627        problem, but was untidy.
628    
629    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
630        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
631        included within another project.
632    
633    24. Steven Van Ingelgem's patches to add more options to the CMake support,
634        slightly modified by me:
635    
636          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
637              not building pcregrep.
638    
639          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
640              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
641    
642    25. Forward references, both numeric and by name, in patterns that made use of
643        duplicate group numbers, could behave incorrectly or give incorrect errors,
644        because when scanning forward to find the reference group, PCRE was not
645        taking into account the duplicate group numbers. A pattern such as
646        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
647    
648    26. Changed a few more instances of "const unsigned char *" to USPTR, making
649        the feature of a custom pointer more persuasive (as requested by a user).
650    
651    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
652        pcretest.c, inside #ifndefs, because it seems they are sometimes already
653        pre-defined.
654    
655    28. Added support for (*UTF8) at the start of a pattern.
656    
657    29. Arrange for flags added by the "release type" setting in CMake to be shown
658        in the configuration summary.
659    
660    
661    Version 7.8 05-Sep-08
662    ---------------------
663    
664    1.  Replaced UCP searching code with optimized version as implemented for Ad
665        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
666        stage table and inline lookup instead of a function, giving speed ups of 2
667        to 5 times on some simple patterns that I tested. Permission was given to
668        distribute the MultiStage2.py script that generates the tables (it's not in
669        the tarball, but is in the Subversion repository).
670    
671    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
672        scripts.
673    
674    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
675        a group with a zero qualifier. The result of the study could be incorrect,
676        or the function might crash, depending on the pattern.
677    
678    4.  Caseless matching was not working for non-ASCII characters in back
679        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
680        It now works when Unicode Property Support is available.
681    
682    5.  In pcretest, an escape such as \x{de} in the data was always generating
683        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
684        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
685        truncation.
686    
687    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
688    
689    7.  Added two (int) casts to pcregrep when printing the difference of two
690        pointers, in case they are 64-bit values.
691    
692    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
693        test 2 if it fails.
694    
695    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
696        and a #define of that name to empty if it is not externally set. This is to
697        allow users of MSVC to set it if necessary.
698    
699    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
700        the convenience functions in the pcre_get.c source file.
701    
702    11. An option change at the start of a pattern that had top-level alternatives
703        could cause overwriting and/or a crash. This command provoked a crash in
704        some environments:
705    
706          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
707    
708        This potential security problem was recorded as CVE-2008-2371.
709    
710    12. For a pattern where the match had to start at the beginning or immediately
711        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
712        pcre_dfa_exec() could read past the end of the passed subject if there was
713        no match. To help with detecting such bugs (e.g. with valgrind), I modified
714        pcretest so that it places the subject at the end of its malloc-ed buffer.
715    
716    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
717        exec() might read past the end of the data buffer in UTF-8 mode.
718    
719    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
720        the data contained the byte 0x85 as part of a UTF-8 character within its
721        first line. This applied both to normal and DFA matching.
722    
723    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
724        /^[^d]*?$/8 failed to match "abc".
725    
726    16. Added a missing copyright notice to pcrecpp_internal.h.
727    
728    17. Make it more clear in the documentation that values returned from
729        pcre_exec() in ovector are byte offsets, not character counts.
730    
731    18. Tidied a few places to stop certain compilers from issuing warnings.
732    
733    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
734        supplied by Stefan Weber. I made a further small update for 7.8 because
735        there is a change of source arrangements: the pcre_searchfuncs.c module is
736        replaced by pcre_ucd.c.
737    
738    
739    Version 7.7 07-May-08
740    ---------------------
741    
742    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
743        a string to a long long, pretend we don't even have a long long." This is
744        done by checking for the strtoq, strtoll, and _strtoi64 functions.
745    
746    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
747        pre-7.6 versions, which defined a global no_arg variable instead of putting
748        it in the RE class. (See also #8 below.)
749    
750    3.  Remove a line of dead code, identified by coverity and reported by Nuno
751        Lopes.
752    
753    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
754    
755        (1) The include/exclude patterns were being applied to the whole pathnames
756            of files, instead of just to the final components.
757    
758        (2) If there was more than one level of directory, the subdirectories were
759            skipped unless they satisfied the include/exclude conditions. This is
760            inconsistent with GNU grep (and could even be seen as contrary to the
761            pcregrep specification - which I improved to make it absolutely clear).
762            The action now is always to scan all levels of directory, and just
763            apply the include/exclude patterns to regular files.
764    
765    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
766        --exclude_dir in the tests to avoid scanning .svn directories.
767    
768    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
769        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
770        doesn't support NULs in patterns.
771    
772    7.  Added some missing "const"s to declarations of static tables in
773        pcre_compile.c and pcre_dfa_exec.c.
774    
775    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
776        caused by fix #2  above. (Subsequently also a second patch to fix the
777        first patch. And a third patch - this was a messy problem.)
778    
779    9.  Applied Craig's patch to remove the use of push_back().
780    
781    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
782        matching function regexec().
783    
784    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
785        which, however, unlike Perl's \g{...}, are subroutine calls, not back
786        references. PCRE supports relative numbers with this syntax (I don't think
787        Oniguruma does).
788    
789    12. Previously, a group with a zero repeat such as (...){0} was completely
790        omitted from the compiled regex. However, this means that if the group
791        was called as a subroutine from elsewhere in the pattern, things went wrong
792        (an internal error was given). Such groups are now left in the compiled
793        pattern, with a new opcode that causes them to be skipped at execution
794        time.
795    
796    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
797        to the way PCRE behaves:
798    
799        (a) A lone ] character is dis-allowed (Perl treats it as data).
800    
801        (b) A back reference to an unmatched subpattern matches an empty string
802            (Perl fails the current match path).
803    
804        (c) A data ] in a character class must be notated as \] because if the
805            first data character in a class is ], it defines an empty class. (In
806            Perl it is not possible to have an empty class.) The empty class []
807            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
808            The negative empty class [^] matches any one character, independently
809            of the DOTALL setting.
810    
811    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
812        non-existent subpattern following a character class starting with ']' and
813        containing () gave an internal compiling error instead of "reference to
814        non-existent subpattern". Fortunately, when the pattern did exist, the
815        compiled code was correct. (When scanning forwards to check for the
816        existencd of the subpattern, it was treating the data ']' as terminating
817        the class, so got the count wrong. When actually compiling, the reference
818        was subsequently set up correctly.)
819    
820    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
821        it was being rejected as not supported by pcre_dfa_exec(), even though
822        other assertions are supported. I have made pcre_dfa_exec() support
823        (*FAIL).
824    
825    16. The implementation of 13c above involved the invention of a new opcode,
826        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
827        cannot be changed at match time, I realized I could make a small
828        improvement to matching performance by compiling OP_ALLANY instead of
829        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
830        on the OP_ANY path.
831    
832    17. Compiling pcretest on Windows with readline support failed without the
833        following two fixes: (1) Make the unistd.h include conditional on
834        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
835    
836    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
837        ncurses library to be included for pcretest when ReadLine support is
838        requested, but also to allow for it to be overridden. This patch came from
839        Daniel Bergström.
840    
841    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
842        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
843        any errors with the current Unicode tables. Thanks to Peter Kankowski for
844        spotting this.
845    
846    
847    Version 7.6 28-Jan-08
848    ---------------------
849    
850    1.  A character class containing a very large number of characters with
851        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
852        overflow.
853    
854    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
855        HAVE_LONG_LONG is not defined.
856    
857    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
858        bring them up to date and include new features. This patch includes:
859    
860        - Fixed PH's badly added libz and libbz2 support.
861        - Fixed a problem with static linking.
862        - Added pcredemo. [But later removed - see 7 below.]
863        - Fixed dftables problem and added an option.
864        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
865            HAVE_LONG_LONG.
866        - Added readline support for pcretest.
867        - Added an listing of the option settings after cmake has run.
868    
869    4.  A user submitted a patch to Makefile that makes it easy to create
870        "pcre.dll" under mingw when using Configure/Make. I added stuff to
871        Makefile.am that cause it to include this special target, without
872        affecting anything else. Note that the same mingw target plus all
873        the other distribution libraries and programs are now supported
874        when configuring with CMake (see 6 below) instead of with
875        Configure/Make.
876    
877    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
878        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
879        exported in the Windows port". It has not yet been confirmed that the patch
880        solves the problem, but it does no harm.
881    
882    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
883        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
884        with CMake, and also correct the comment about stack recursion.
885    
886    7.  Remove the automatic building of pcredemo from the ./configure system and
887        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
888        of a program that users should build themselves after PCRE is installed, so
889        building it automatically is not really right. What is more, it gave
890        trouble in some build environments.
891    
892    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
893    
894    
895    Version 7.5 10-Jan-08
896    ---------------------
897    
898    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
899        values in parens when parsing an RE using the C++ wrapper."
900    
901    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
902        Characters greater than 255 were excluded from the class instead of being
903        included.
904    
905    3.  The same bug as (2) above applied to negated POSIX classes such as
906        [:^space:].
907    
908    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
909        defined or documented. It seems to have been a typo for PCRE_STATIC, so
910        I have changed it.
911    
912    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
913        first named subpattern) and a construct such as (?&a) would reference the
914        first named subpattern whose name started with "a" (in other words, the
915        length check was missing). Both these problems are fixed. "Subpattern name
916        expected" is now given for (?&) (a zero-length name), and this patch also
917        makes it give the same error for \k'' (previously it complained that that
918        was a reference to a non-existent subpattern).
919    
920    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
921        this is right because (?- can be followed by option settings as well as by
922        digits. I have, however, made the messages clearer.
923    
924    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
925        than the number used in the conditional) now cause a compile-time error.
926        This is actually not compatible with Perl, which accepts such patterns, but
927        treats the conditional as always being FALSE (as PCRE used to), but it
928        seems to me that giving a diagnostic is better.
929    
930    8.  Change "alphameric" to the more common word "alphanumeric" in comments
931        and messages.
932    
933    9.  Fix two occurrences of "backslash" in comments that should have been
934        "backspace".
935    
936    10. Remove two redundant lines of code that can never be obeyed (their function
937        was moved elsewhere).
938    
939    11. The program that makes PCRE's Unicode character property table had a bug
940        which caused it to generate incorrect table entries for sequences of
941        characters that have the same character type, but are in different scripts.
942        It amalgamated them into a single range, with the script of the first of
943        them. In other words, some characters were in the wrong script. There were
944        thirteen such cases, affecting characters in the following ranges:
945    
946          U+002b0 - U+002c1
947          U+0060c - U+0060d
948          U+0061e - U+00612
949          U+0064b - U+0065e
950          U+0074d - U+0076d
951          U+01800 - U+01805
952          U+01d00 - U+01d77
953          U+01d9b - U+01dbf
954          U+0200b - U+0200f
955          U+030fc - U+030fe
956          U+03260 - U+0327f
957          U+0fb46 - U+0fbb1
958          U+10450 - U+1049d
959    
960    12. The -o option (show only the matching part of a line) for pcregrep was not
961        compatible with GNU grep in that, if there was more than one match in a
962        line, it showed only the first of them. It now behaves in the same way as
963        GNU grep.
964    
965    13. If the -o and -v options were combined for pcregrep, it printed a blank
966        line for every non-matching line. GNU grep prints nothing, and pcregrep now
967        does the same. The return code can be used to tell if there were any
968        non-matching lines.
969    
970    14. Added --file-offsets and --line-offsets to pcregrep.
971    
972    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
973        infinitely looping recursion. The bug was that positive lookaheads were not
974        being skipped when checking for a possible empty match (negative lookaheads
975        and both kinds of lookbehind were skipped).
976    
977    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
978        inclusion of <windows.h> to before rather than after the definition of
979        INVALID_FILE_ATTRIBUTES (patch from David Byron).
980    
981    17. Specifying a possessive quantifier with a specific limit for a Unicode
982        character property caused pcre_compile() to compile bad code, which led at
983        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
984        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
985        caused the error; without that there was no problem.
986    
987    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
988    
989    19. Added --enable-pcretest-libreadline.
990    
991    20. In pcrecpp.cc, the variable 'count' was incremented twice in
992        RE::GlobalReplace(). As a result, the number of replacements returned was
993        double what it should be. I removed one of the increments, but Craig sent a
994        later patch that removed the other one (the right fix) and added unit tests
995        that check the return values (which was not done before).
996    
997    21. Several CMake things:
998    
999        (1) Arranged that, when cmake is used on Unix, the libraries end up with
1000            the names libpcre and libpcreposix, not just pcre and pcreposix.
1001    
1002        (2) The above change means that pcretest and pcregrep are now correctly
1003            linked with the newly-built libraries, not previously installed ones.
1004    
1005        (3) Added PCRE_SUPPORT_LIBREADLINE, PCRE_SUPPORT_LIBZ, PCRE_SUPPORT_LIBBZ2.
1006    
1007    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
1008        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
1009        UTF-8 newline character). The key issue is that the pattern starts .*;
1010        this means that the match must be either at the beginning, or after a
1011        newline. The bug was in the code for advancing after a failed match and
1012        checking that the new position followed a newline. It was not taking
1013        account of UTF-8 characters correctly.
1014    
1015    23. PCRE was behaving differently from Perl in the way it recognized POSIX
1016        character classes. PCRE was not treating the sequence [:...:] as a
1017        character class unless the ... were all letters. Perl, however, seems to
1018        allow any characters between [: and :], though of course it rejects as
1019        unknown any "names" that contain non-letters, because all the known class
1020        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
1021        for example, whereas PCRE did not - it did not recognize a POSIX character
1022        class. This seemed a bit dangerous, so the code has been changed to be
1023        closer to Perl. The behaviour is not identical to Perl, because PCRE will
1024        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
1025        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
1026        Perl does, and where it didn't before.
1027    
1028    24. Rewrite so as to remove the single use of %n from pcregrep because in some
1029        Windows environments %n is disabled by default.
1030    
1031    
1032    Version 7.4 21-Sep-07
1033    ---------------------
1034    
1035    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
1036        means that a class such as [\s] counted as "explicit reference to CR or
1037        LF". That isn't really right - the whole point of the change was to try to
1038        help when there was an actual mention of one of the two characters. So now
1039        the change happens only if \r or \n (or a literal CR or LF) character is
1040        encountered.
1041    
1042    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
1043        of both had grown to the point where there were only 3 bits left.
1044        Fortunately, there was spare space in the data structure, and so I have
1045        moved the internal flags into a new 16-bit field to free up more option
1046        bits.
1047    
1048    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
1049        but did not set the internal JCHANGED flag - either of these is enough to
1050        control the way the "get" function works - but the PCRE_INFO_JCHANGED
1051        facility is supposed to tell if (?J) was ever used, so now (?J) at the
1052        start sets both bits.
1053    
1054    4.  Added options (at build time, compile time, exec time) to change \R from
1055        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
1056    
1057    5.  doc/pcresyntax.html was missing from the distribution.
1058    
1059    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
1060        compatibility, even though it is no longer used.
1061    
1062    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
1063        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
1064        windows.h file is present (where different names are used). [This was
1065        reversed later after testing - see 16 below.]
1066    
1067    8.  Changed all #include <config.h> to #include "config.h". There were also
1068        some further <pcre.h> cases that I changed to "pcre.h".
1069    
1070    9.  When pcregrep was used with the --colour option, it missed the line ending
1071        sequence off the lines that it output.
1072    
1073    10. It was pointed out to me that arrays of string pointers cause lots of
1074        relocations when a shared library is dynamically loaded. A technique of
1075        using a single long string with a table of offsets can drastically reduce
1076        these. I have refactored PCRE in four places to do this. The result is
1077        dramatic:
1078    
1079          Originally:                          290
1080          After changing UCP table:            187
1081          After changing error message table:   43
1082          After changing table of "verbs"       36
1083          After changing table of Posix names   22
1084    
1085        Thanks to the folks working on Gregex for glib for this insight.
1086    
1087    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
1088        unicode-properties was also set.
1089    
1090    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
1091    
1092    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
1093        checked only for CRLF.
1094    
1095    14. Added casts to pcretest.c to avoid compiler warnings.
1096    
1097    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
1098    
1099    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
1100        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
1101        entirely. This removes changes made in 7 above.
1102    
1103    17. The CMake files have been updated, and there is now more information about
1104        building with CMake in the NON-UNIX-USE document.
1105    
1106    
1107    Version 7.3 28-Aug-07
1108    ---------------------
1109    
1110     1. In the rejigging of the build system that eventually resulted in 7.1, the
1111        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
1112        brackets there is not right, since it causes compilers to look for an
1113        installed pcre.h, not the version that is in the source that is being
1114        compiled (which of course may be different). I have changed it back to:
1115    
1116          #include "pcre.h"
1117    
1118        I have a vague recollection that the change was concerned with compiling in
1119        different directories, but in the new build system, that is taken care of
1120        by the VPATH setting the Makefile.
1121    
1122     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
1123        when the subject happened to end in the byte 0x85 (e.g. if the last
1124        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
1125        characters but of course it shouldn't be taken as a newline when it is part
1126        of another character. The bug was that, for an unlimited repeat of . in
1127        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
1128        characters when looking for a newline.
1129    
1130     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
1131    
1132     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
1133        in debug output.
1134    
1135     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
1136        long printing in the pcrecpp unittest when running under MinGW.
1137    
1138     6. ESC_K was left out of the EBCDIC table.
1139    
1140     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
1141        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
1142        limit also applies to "virtual nesting" when a pattern is recursive, and in
1143        this case 1000 isn't so big. I have been able to remove this limit at the
1144        expense of backing off one optimization in certain circumstances. Normally,
1145        when pcre_exec() would call its internal match() function recursively and
1146        immediately return the result unconditionally, it uses a "tail recursion"
1147        feature to save stack. However, when a subpattern that can match an empty
1148        string has an unlimited repetition quantifier, it no longer makes this
1149        optimization. That gives it a stack frame in which to save the data for
1150        checking that an empty string has been matched. Previously this was taken
1151        from the 1000-entry workspace that had been reserved. So now there is no
1152        explicit limit, but more stack is used.
1153    
1154     8. Applied Daniel's patches to solve problems with the import/export magic
1155        syntax that is required for Windows, and which was going wrong for the
1156        pcreposix and pcrecpp parts of the library. These were overlooked when this
1157        problem was solved for the main library.
1158    
1159     9. There were some crude static tests to avoid integer overflow when computing
1160        the size of patterns that contain repeated groups with explicit upper
1161        limits. As the maximum quantifier is 65535, the maximum group length was
1162        set at 30,000 so that the product of these two numbers did not overflow a
1163        32-bit integer. However, it turns out that people want to use groups that
1164        are longer than 30,000 bytes (though not repeat them that many times).
1165        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
1166        made it possible to implement the integer overflow checks in a much more
1167        dynamic way, which I have now done. The artificial limitation on group
1168        length has been removed - we now have only the limit on the total length of
1169        the compiled pattern, which depends on the LINK_SIZE setting.
1170    
1171    10. Fixed a bug in the documentation for get/copy named substring when
1172        duplicate names are permitted. If none of the named substrings are set, the
1173        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
1174        empty string.
1175    
1176    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
1177        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
1178        because the ] is interpreted as the first data character and the
1179        terminating ] is not found. PCRE has been made compatible with Perl in this
1180        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
1181        cause memory overwriting.
1182    
1183    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
1184        string has been matched (to stop an infinite loop). It was not recognizing
1185        a conditional subpattern that could match an empty string if that
1186        subpattern was within another subpattern. For example, it looped when
1187        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
1188        condition was not nested. This bug has been fixed.
1189    
1190    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
1191        past the start of the subject in the presence of bytes with the top bit
1192        set, for example "\x8aBCD".
1193    
1194    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
1195        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
1196    
1197    14. Optimized (?!) to (*FAIL).
1198    
1199    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
1200        This restricts code points to be within the range 0 to 0x10FFFF, excluding
1201        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
1202        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
1203        does: it's just the validity check that is more restrictive.
1204    
1205    16. Inserted checks for integer overflows during escape sequence (backslash)
1206        processing, and also fixed erroneous offset values for syntax errors during
1207        backslash processing.
1208    
1209    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
1210        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
1211    
1212    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
1213        caused an overrun.
1214    
1215    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
1216        something other than just ASCII characters) inside a group that had an
1217        unlimited repeat caused a loop at compile time (while checking to see
1218        whether the group could match an empty string).
1219    
1220    20. Debugging a pattern containing \p or \P could cause a crash. For example,
1221        [\P{Any}] did so. (Error in the code for printing property names.)
1222    
1223    21. An orphan \E inside a character class could cause a crash.
1224    
1225    22. A repeated capturing bracket such as (A)? could cause a wild memory
1226        reference during compilation.
1227    
1228    23. There are several functions in pcre_compile() that scan along a compiled
1229        expression for various reasons (e.g. to see if it's fixed length for look
1230        behind). There were bugs in these functions when a repeated \p or \P was
1231        present in the pattern. These operators have additional parameters compared
1232        with \d, etc, and these were not being taken into account when moving along
1233        the compiled data. Specifically:
1234    
1235        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
1236            length.
1237    
1238        (b) An item such as \pL+ within a repeated group could cause crashes or
1239            loops.
1240    
1241        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
1242            "reference to non-existent subpattern" error.
1243    
1244        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
1245    
1246    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
1247        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
1248    
1249    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
1250    
1251    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
1252        character were causing crashes (broken optimization).
1253    
1254    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
1255        \p or \P) caused a compile-time loop.
1256    
1257    28. More problems have arisen in unanchored patterns when CRLF is a valid line
1258        break. For example, the unstudied pattern [\r\n]A does not match the string
1259        "\r\nA" because change 7.0/46 below moves the current point on by two
1260        characters after failing to match at the start. However, the pattern \nA
1261        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
1262        the same is true. There doesn't seem any very clean way out of this, but
1263        what I have chosen to do makes the common cases work: PCRE now takes note
1264        of whether there can be an explicit match for \r or \n anywhere in the
1265        pattern, and if so, 7.0/46 no longer applies. As part of this change,
1266        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
1267        pattern has explicit CR or LF references.
1268    
1269    29. Added (*CR) etc for changing newline setting at start of pattern.
1270    
1271    
1272    Version 7.2 19-Jun-07
1273  ---------------------  ---------------------
1274    
1275   1. If the fr_FR locale cannot be found for test 3, try the "french" locale,   1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
1276      which is apparently normally available under Windows.      which is apparently normally available under Windows.
1277    
1278     2. Re-jig the pcregrep tests with different newline settings in an attempt
1279        to make them independent of the local environment's newline setting.
1280    
1281     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
1282    
1283     4. Some of the "internals" tests were previously cut out when the link size
1284        was not 2, because the output contained actual offsets. The recent new
1285        "Z" feature of pcretest means that these can be cut out, making the tests
1286        usable with all link sizes.
1287    
1288     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
1289        stack recursion. This gives a massive performance boost under BSD, but just
1290        a small improvement under Linux. However, it saves one field in the frame
1291        in all cases.
1292    
1293     6. Added more features from the forthcoming Perl 5.10:
1294    
1295        (a) (?-n) (where n is a string of digits) is a relative subroutine or
1296            recursion call. It refers to the nth most recently opened parentheses.
1297    
1298        (b) (?+n) is also a relative subroutine call; it refers to the nth next
1299            to be opened parentheses.
1300    
1301        (c) Conditions that refer to capturing parentheses can be specified
1302            relatively, for example, (?(-2)... or (?(+3)...
1303    
1304        (d) \K resets the start of the current match so that everything before
1305            is not part of it.
1306    
1307        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
1308    
1309        (f) \g{name} is another synonym - part of Perl 5.10's unification of
1310            reference syntax.
1311    
1312        (g) (?| introduces a group in which the numbering of parentheses in each
1313            alternative starts with the same number.
1314    
1315        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
1316    
1317     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
1318        PCRE_INFO_JCHANGED.
1319    
1320     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
1321        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
1322        for detecting groups that can match an empty string.
1323    
1324     9. A pattern with a very large number of alternatives (more than several
1325        hundred) was running out of internal workspace during the pre-compile
1326        phase, where pcre_compile() figures out how much memory will be needed. A
1327        bit of new cunning has reduced the workspace needed for groups with
1328        alternatives. The 1000-alternative test pattern now uses 12 bytes of
1329        workspace instead of running out of the 4096 that are available.
1330    
1331    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
1332    
1333    11. Applied patch from Google to remove an optimization that didn't quite work.
1334        The report of the bug said:
1335    
1336          pcrecpp::RE("a*").FullMatch("aaa") matches, while
1337          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
1338          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
1339    
1340    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
1341        it matched the wrong number of bytes.
1342    
1343    
1344  Version 7.1 24-Apr-07  Version 7.1 24-Apr-07
1345  ---------------------  ---------------------

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