On Feb 16, 2005, at 6:57 AM, Chuck Silvers wrote:

> /* This provides functionality somewhat similar to mmap() but using 
> read().
>  * It gives sliding window access to a file.  mmap() is not used 
> because of
>  * the possibility of another program (such as a mailer) truncating the
>  * file thus giving us a SIGBUS. */
>
> so they were just being a bit lazy.

Not only are they lazy, on NetBSD that simply isn't true.  I wrote a 
test case for this after discussing it with Luke Mewburn, who in turn 
had discussed this very issue with the rsync/samba guys.  As far as I 
can tell, they're working around a bug in Linux.

-- thorpej