David Brownell wrote:
>
> > >2. Why open with O_RDWR? Is that a requirement of usbdevfs?
>
> Basically, yes -- even when performing "read" control messages.
> Not a requirement I much like seeing imposed.
IMNSHO one wants to give normal users the ability to see what
devices are connected (they can read the stored descriptors), but
one does not want an arbitrary user to crash an arbitrary USB device.
Many USB devices can be crashed by sending an inappropriate control
request even if it is only a read request. That's why write perms
are required even for read requests. And btw. a read request
also requires a write phase on the USB bus.
Tom
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