[Starkit] corruption of starkits by double access

[Jean-Claude Wippler]

Steve,

>> +       if {![mk::view size $db.dirs] || [mk::get $db.dirs!0  
>> parent] !
>> = -1} {
>> +           mk::set $db.dirs!0 parent -1
>> +       }
[...]

> This seems to work OK on NetBSD - I don't have a build environment for
> Windows just now.    Isn't there the basis for a platform-independent
> general mechanism here, marking a starkit internally as already  
> open or not?
> I don't really understand the role of the -1, and I don't think  
> it's sane for
> us to maintain a separate branch of tclkit to handle this problem.

No, that's not what it's doing.  Every MK dataset starts out as  
empty.  For a VFS structure, there needs to always be one "root" row,  
specially marked as -1.  So that's what the above does: if the MK  
file is brand new, make sure it has that special row.  The key here  
is that it won't write a -1 if that row already exists (and  
presumably has a -1 in there anyway).  So it won't write at all,  
which avoids internally flagging the dataset as dirty, which in turn  
avoids doing anything on commit.  If commit's don't write anything,  
then open/close is harmless - even in r/w mode, and even without  
locking.

I was not planning on letting you maintain a separate branch, just  
that I hadn't tested it - so since you say it works (you did,  
right?), I'll add it to every Tclkit built from now on.

-jcw