Re: [PATCH 001/001] CHAR DRIVERS: a simple device to give daemons a /sys-like interface

Bob Smith
2013-08-07T19:39:51Z

Greg Kroah-Hartman wrote:
>> * sudo chmod 666 /dev/proxyout /dev/proxyctrl
> That's mighty permissive :(
For a demo it might be OK.

BUT: I think I should modify the module to forward a close request
(write 0 bytes) only if the sender UID matched the proxy node's UID.
This might not be strictly required but is a security nice to have.

>> * gcc -o pxtest pxtest.c
>> * ./pxtest &
>> * cat /dev/proxyout # view the output
>> * (switch to another terminal window)
>> * cat /dev/proxyctrl # what is the offset?
>> * echo 2 > /dev/proxyctrl # set offset to 2
>> */
>
> I really don't understand this, you just have two programs talking to
> each other, passing the data blindly through the kernel. Again, we
> already have over 10 different ways to do IPC these days, are you _sure_
> that _none_ of them work for you like this? You have gone and looked at
> them all, right?

All along I've had a clear goal. I want to configure a running program
the same way I configure the kernel. It is simple and I don't need any
language bindings.
cat /dev/proxyctrl # what is the offset?
echo 2 > /dev/proxyctrl # set offset to 2

Yes, I am sure that nothing else will do. A named pipe is the closest
but it has a buffer and is not bidirectional. I am also convinced that
there is no way to do what I want with fewer lines of code.

thanks
Bob Smith