Re: [Qemu-devel] [PATCH VERSION 3] Disk image exclusive and shared locks.

[Jamie Lokier <jamie@shareable.org>]

Kevin Wolf wrote:
> > You might think the user could do that by setting the permissions to
> > read-only, but root ignores file permissions.  (That's why we need a
> > "ro" option too).
> 
> We do have readonly=on|off.

Sure, but if you have to do that for safe behaviour when running qemu
as root, and you don't need it when running qemu as a user because you
get into the habit of depending on file permissions, that's asking for
an accident to happen.

I know this, because I have accidentally opened read-only images
writable when putting "sudo" at the start of a qemu command to make
something completely unrelated work (networking).

Imho, the open-writable-if-permissions-allow-else-fallback-to-readable
behaviour should either be abolished entirely (not such a bad idea),
or be made to behave consistently no matter what user is used to run qemu.

-- Jamie