Xen devel - Mar 2006 - [PATCH] safer checks in network-bridge script

The network-bridge script is fragile because of how grep is used.  As
one example, if I already have "xenbridge", I can''t create
"xenbr".
(It''s actually worse than that, because it''s even grepping the
header
output by brctl show.)

Assuming dom0 is on Linux with /sys mounted (is that a safe
assumption?) we can check for the existence of a bridge, and check if a
device is on the bridge, by looking in /sys.  The attached patch does
that.

If that''s not a safe assumption, at least add "-w" to the two
instances
of grep.  Not perfect, but better.



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On Thu, Mar 09, 2006 at 06:27:33PM -0500, Charles Coffing wrote:
> The network-bridge script is fragile because of how grep is used.  As
> one example, if I already have "xenbridge", I can''t
create "xenbr".
> (It''s actually worse than that, because it''s even
grepping the header
> output by brctl show.)
> 
> Assuming dom0 is on Linux with /sys mounted (is that a safe
> assumption?) we can check for the existence of a bridge, and check if a
> device is on the bridge, by looking in /sys.  The attached patch does
> that.
> 
> If that''s not a safe assumption, at least add "-w" to
the two instances
> of grep.  Not perfect, but better.
Thanks for this, Charles.  I''m not sure that it''s safe to rely
upon /sys
though.  Could you rework this patch to use /sys/class if it exists, but falls
back to using grep / brctl otherwise (and fix the grep)?

Thanks,

Ewan.

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