cdrdao no-disc ejection & --eject (#93)

* cdrdao: eject empty disc while reading toc

- introduce EjectError
- move {eject,load,unmount}_device to program.utils

* remove duplicated eject

* remove unnecessary ejection

* add --eject option

morituri/program/utils.py

@@ -0,0 +1,35 @@
+import os
+
+import logging
+logger = logging.getLogger(__name__)
+
+
+def eject_device(device):
+    """
+    Eject the given device.
+    """
+    logger.debug("ejecting device %s", device)
+    os.system('eject %s' % device)
+
+
+def load_device(device):
+    """
+    Load the given device.
+    """
+    logger.debug("loading (eject -t) device %s", device)
+    os.system('eject -t %s' % device)
+    
+    
+def unmount_device(device):
+    """
+    Unmount the given device if it is mounted, as happens with automounted
+    data tracks.
+
+    If the given device is a symlink, the target will be checked.
+    """
+    device = os.path.realpath(device)
+    logger.debug('possibly unmount real path %r' % device)
+    proc = open('/proc/mounts').read()
+    if device in proc:
+        print 'Device %s is mounted, unmounting' % device
+        os.system('umount %s' % device)