Re: [Xen-devel] [PATCH] xl: Special case tap/aio for disk validation

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Thu, 2011-01-27 at 16:23 +0000, Ian Jackson wrote: 
> Ian Campbell writes ("Re: [Xen-devel] [PATCH] xl: Special case tap/aio for 
> disk validation"):
> > FWIW xend notices a relative path and wacks a "/dev/" on the front.
> 
> Oh dear.  So is the syntax
>    some:pile:of:useless:prefixes:sponge
> allowed to mean /dev/sponge ?  What if you want to refer to
> /dev/sponge:1 ?  I guess that probably doesn't work right now.
> 
> So the right algorithm is:
>    - rhs starts with '/': it's a pathname
>    - rhs has a colon: it's a prefix
>    - rhs has neither: hope it's a pathname in /dev
> ?

Sounds about right.

FWIW from xend:

def _parse_uname(uname):
    fn = taptype = None
    if uname.find(":") != -1:
        (typ, fn) = uname.split(":", 1)

        if typ in ("phy", "drbd") and not fn.startswith("/"):
            fn = "/dev/%s" %(fn,)
               
        if typ in ("tap", "tap2"):
            (taptype, fn) = fn.split(":", 1)
    return (fn, taptype)

/me cries.



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