On Mon, Nov 04, 2019 at 09:23:15PM +0100, Michal Suchanek wrote:
> When autoclose is set (kernel default but many distributions reverse the
> setting) opening a CD-rom device causes the tray to close.
>
> The function of blkid is to report the current state of the device and
> not to change it. Hence it should use O_NONBLOCK when opening the
> device to avoid closing a CD-rom tray.
I can imagine this as optional solution (command line option), but I
have doubts to use O_NONBLOCK by default for all block devices. I have
no example, but it sounds like a way how to introduce regressions in
libblkid behavior. (Any kernel guy around?) Is it really only cdrom
driver(s) where O_NONBLOCK has any impact? What about USB, some random
SCSI, ... I don't know.
The another problem is that the library does not have to open the device,
you can use already open file descriptor (blkid_probe_set_device()).
So, in many cases the patch will have no effect.
> blkid is used liberally in scripts so it can potentially interfere with
> the user operating the CD-rom hardware.
It's better to use lsblk in script, it reads info from udev -- call
blindly blkid(8) is usually overkill.
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
