udiskie: Add eject functionality for a drive

When a block device with a filesystem is selected for ejecting, all the
filesystems on the drive to which the selected filesystem belongs will first be
unmounted. Finally the drive itself is ejected.

Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/udiskie/templates/udiskie.html

@@ -36,6 +36,7 @@
         <th>{% trans "Size" %}</th>
         <th>{% trans "Filesystem" %}</th>
         <th>{% trans "Mount Point" %}</th>
+        <th>{% trans "Actions" %}</th>
       </tr>
     </thead>
     <tbody>
@@ -46,6 +47,18 @@
           <td>{{ device.size }}</td>
           <td>{{ device.filesystem_type }}</td>
           <td>{{ device.mount_points|join:', ' }}</td>
+          <td>
+            {% if device.mount_points %}
+              <form class="form" method="post"
+                    action="{% url 'udiskie:eject' device.device|urlencode:"" %}">
+                {% csrf_token %}
+
+                <button type="submit"
+                        class="btn btn-sm btn-default glyphicon glyphicon-eject">
+                </button>
+              </form>
+            {% endif %}
+          </td>
         </tr>
       {% endfor %}
     </tbody>

plinth/modules/udiskie/udisks2.py

@@ -18,14 +18,24 @@
 Library for interacting with udisks2 D-Bus service.
 """
 
+from django.utils.translation import ugettext as _
+
 from plinth import utils
 from plinth.modules.storage import format_bytes
 
+glib = utils.import_from_gi('GLib', '2.0')
+udisks = utils.import_from_gi('UDisks', '2.0')
+
+
+def _get_options():
+    """Return the common options used for udisks2 operations."""
+    options = glib.Variant(
+        'a{sv}', {'auth.no_user_interaction': glib.Variant('b', True)})
+    return options
+
 
 def list_devices():
     """List devices that can be ejected."""
-    udisks = utils.import_from_gi('UDisks', '2.0')
-
     client = udisks.Client.new_sync()
     object_manager = client.get_object_manager()
 
@@ -60,3 +70,105 @@ def list_devices():
         devices.append(device)
 
     return devices
+
+
+def eject_drive_of_device(device_path):
+    """Eject a device after unmounting all of its partitions.
+
+    Return the details (model, vendor) of drives ejected.
+    """
+    client = udisks.Client.new_sync()
+    object_manager = client.get_object_manager()
+
+    found_objects = [
+        obj for obj in object_manager.get_objects()
+        if obj.get_block() and obj.get_block().props.device == device_path
+    ]
+
+    if not found_objects:
+        raise ValueError(
+            _('No such device - {device_path}').format(
+                device_path=device_path))
+
+    obj = found_objects[0]
+
+    # Unmount filesystems
+    block_device = obj.get_block()
+    drive_object_path = block_device.props.drive
+    if drive_object_path != '/':
+        umount_all_filesystems_of_drive(drive_object_path)
+    else:
+        # Block device has not associated drive
+        umount_filesystem(obj.get_filesystem())
+
+    # Eject the drive
+    drive = client.get_drive_for_block(block_device)
+    if drive:
+        drive.call_eject_sync(_get_options(), None)
+        return {
+            'vendor': drive.props.vendor,
+            'model': drive.props.model,
+        }
+
+    return None
+
+
+def umount_filesystem(filesystem):
+    """Unmount a filesystem """
+    if filesystem and filesystem.props.mount_points:
+        filesystem.call_unmount_sync(_get_options())
+
+
+def umount_all_filesystems_of_drive(drive_object_path):
+    """Unmount all filesystems on block devices of a drive."""
+    client = udisks.Client.new_sync()
+    object_manager = client.get_object_manager()
+
+    for obj in object_manager.get_objects():
+        block_device = obj.get_block()
+        if not block_device or block_device.props.drive != drive_object_path:
+            continue
+
+        umount_filesystem(obj.get_filesystem())
+
+
+def get_error_message(error):
+    """Return an error message given an exception."""
+    if error.matches(udisks.Error.quark(), udisks.Error.FAILED):
+        message = _('The operation failed.')
+    elif error.matches(udisks.Error.quark(), udisks.Error.CANCELLED):
+        message = _('The operation was cancelled.')
+    elif error.matches(udisks.Error.quark(), udisks.Error.ALREADY_UNMOUNTING):
+        message = _('The device is already unmounting.')
+    elif error.matches(udisks.Error.quark(), udisks.Error.NOT_SUPPORTED):
+        message = _('The operation is not supported due to '
+                    'missing driver/tool support.')
+    elif error.matches(udisks.Error.quark(), udisks.Error.TIMED_OUT):
+        message = _('The operation timed out.')
+    elif error.matches(udisks.Error.quark(), udisks.Error.WOULD_WAKEUP):
+        message = _('The operation would wake up a disk that is '
+                    'in a deep-sleep state.')
+    elif error.matches(udisks.Error.quark(), udisks.Error.DEVICE_BUSY):
+        message = _('Attempting to unmount a device that is busy.')
+    elif error.matches(udisks.Error.quark(), udisks.Error.ALREADY_CANCELLED):
+        message = _('The operation has already been cancelled.')
+    elif error.matches(udisks.Error.quark(), udisks.Error.NOT_AUTHORIZED) or \
+        error.matches(udisks.Error.quark(),
+                      udisks.Error.NOT_AUTHORIZED_CAN_OBTAIN) or \
+        error.matches(udisks.Error.quark(),
+                      udisks.Error.NOT_AUTHORIZED_DISMISSED):
+        message = _('Not authorized to perform the requested operation.')
+    elif error.matches(udisks.Error.quark(), udisks.Error.ALREADY_MOUNTED):
+        message = _('The device is already mounted.')
+    elif error.matches(udisks.Error.quark(), udisks.Error.NOT_MOUNTED):
+        message = _('The device is not mounted.')
+    elif error.matches(udisks.Error.quark(),
+                       udisks.Error.OPTION_NOT_PERMITTED):
+        message = _('Not permitted to use the requested option.')
+    elif error.matches(udisks.Error.quark(),
+                       udisks.Error.MOUNTED_BY_OTHER_USER):
+        message = _('The device is mounted by another user.')
+    else:
+        message = error.message
+
+    return message

plinth/modules/udiskie/urls.py

@@ -20,12 +20,15 @@ URLs for the udiskie module.
 
 from django.conf.urls import url
 
-from .views import UdiskieView
 from plinth.modules import udiskie
 
+from .views import Index, eject
+
 urlpatterns = [
-    url(r'^sys/udiskie/$',
-        UdiskieView.as_view(service_id=udiskie.managed_services[0],
-                            description=udiskie.description,
-                            show_status_block=True), name='index'),
+    url(
+        r'^sys/udiskie/$',
+        Index.as_view(service_id=udiskie.managed_services[0],
+                      description=udiskie.description, show_status_block=True),
+        name='index'),
+    url(r'^sys/udiskie/eject/(?P<device_path>[\w%]+)/$', eject, name='eject'),
 ]

plinth/modules/udiskie/views.py

@@ -18,17 +18,62 @@
 Views for udiskie module.
 """
 
+import urllib.parse
+from logging import Logger
+
+from django.contrib import messages
+from django.shortcuts import redirect
+from django.urls import reverse
+from django.utils.translation import ugettext as _
+from django.views.decorators.http import require_POST
+
 from plinth.views import ServiceView
 
 from . import udisks2
 
+logger = Logger(__name__)
 
-class UdiskieView(ServiceView):
+
+class Index(ServiceView):
     """View to show devices."""
     template_name = 'udiskie.html'
 
-    def get_context_data(self, **kwargs):
+    def get_context_data(self, *args, **kwargs):
         """Return the context data rendering the template."""
         context = super().get_context_data(**kwargs)
         context['devices'] = udisks2.list_devices()
         return context
+
+
+@require_POST
+def eject(request, device_path):
+    """Eject a device, given its path.
+
+    Device path is quoted with slashes written as %2F.
+
+    """
+    device_path = urllib.parse.unquote(device_path)
+
+    try:
+        drive = udisks2.eject_drive_of_device(device_path)
+        if drive:
+            messages.success(
+                request,
+                _('{drive_vendor} {drive_model} can be safely unplugged.')
+                .format(drive_vendor=drive['vendor'],
+                        drive_model=drive['model']))
+        else:
+            messages.success(request, _('Device can be safely unplugged.'))
+    except Exception as exception:
+        try:
+            message = udisks2.get_error_message(exception)
+        except AttributeError:
+            message = str(exception)
+
+        logger.exception('Error ejecting device - %s', message)
+        messages.error(
+            request,
+            _('Error ejecting device: {error_message}').format(
+                error_message=message))
+
+    return redirect(reverse('udiskie:index'))