Question

I’m trying to port an application from using HAL to using pure udev. It is written in python and will use the gudev library, though I would love to see examples in any language. I’m able to get all attached video devices (such as cameras) via:

import gudev

client = gudev.Client(["video4linux"])
for device in client.get_devices():
    print device.get_sysfs_attr("name"), device.get_device_name()

This prints out something like:

USB2.0 UVC WebCam /dev/video0

I am also able to get a list of block devices, but how can I:

1. Tell if it is a CD/DVD drive?

2. Tell if media is currently inserted if the drive supports removable media?

3. Tell what the name/label of the media is (e.g. FUTURAMAS1 for a DVD)?

The original code I am trying to port over is located at http://github.com/danielgtaylor/arista/blob/045a4d48ebfda44bc5d0609618ff795604ee134f/arista/inputs.py

Any and all help would be greatly appreciated!

---

Update: adding answer below.

import gudev

client = gudev.Client(['block'])
for device in client.query_by_subsystem("block"):
    if device.has_property("ID_CDROM"):
        print "Found CD/DVD drive at %s" % device.get_device_file()
        if device.has_property("ID_FS_LABEL"):
            print "Found disc: %s" % device.get_property("ID_FS_LABEL")
        elif device.has_property("ID_FS_TYPE"):
            print "Found disc"
        else:
            print "No disc"

The code above will output data like:

Found CD/DVD drive at /dev/sr0
Found disc: Ubuntu_10.04_i386

Thanks for the help!

Answer 1

Have a look at the device properties:

import gudev

client = gudev.Client(['block'])
for device in client.query_by_subsystem("block"):
    print device
    for device_key in device.get_property_keys():
        print "   property %s: %s" % (device_key, device.get_property(device_key))
    print