| Subject: | Bug in encGlue.c:CallEncode causes TCL_Panic |
System: Tk800_027, perl5.8.7, Debian Sarge, KDE
While tracking back a TCL_Panic when deleting a large selection
in a TK::Text (see
http://groups.google.com/group/comp.lang.perl.tk/browse_thread/thread/af1150eec445ccdf)
I stumbled over the following code in encGlue.c.
677 quiet = get_sv("Tk::encodeFallback",0);
...
723 PUSHMARK(sp);
724 XPUSHs(PerlEncObj(encoding));
725 XPUSHs(stmp);
726 XPUSHs(quiet);
727 PUTBACK;
728 perl_call_method(method,G_SCALAR|G_EVAL);
...
745 if (SvCUR(stmp))
746 {
747 /* This could also be TCL_CONVERT_MULTIBYTE - how do we tell ? */
748 code = TCL_CONVERT_UNKNOWN;
749 break;
750 }
If I understand this right this would call
$encoding->encode( $string, 0 )
unless Tk:encodeFallback is set and expect it to delete the encodes chars
from string or fail with TCL_CONVERT_UNKNOWN (check in line 745) which
will cause the TCL_Panic later in my case.
$encoding is a Encode::Encoding object (Encode::utf8 in my case) and
reading the Encode::Encoding manpage it says
| ->encode($string [,$check])
| MUST return the octet sequence representing $string.
|
| * If $check is true, it SHOULD modify $string in place to remove
| the converted part (i.e. the whole string unless there is an
| error). If perlio_ok() is true, SHOULD becomes MUST.
|
| * If an error occurs, it SHOULD return the octet sequence for the
| fragment of string that has been converted and modify $string in-
| place to remove the converted part leaving it starting with the
| problem fragment. If perlio_ok() is true, SHOULD becomes MUST.
|
| * If $check is is false then "encode" MUST make a "best effort" to
| convert the string - for example, by using a replacement charac-
| ter.
So there is no description what should happen with $string in case $check
is 0 false and conversion was OK. In fact Encode::utf8->encode( $string,0 )
just returns the converting string and leaves $string unchanged. Thus
the test in line 745 will fail even if everything was correct.
If I set $Tk::encodeFallback to true everything is fine, no panic occurs.