Implement mountpoint checking

Don't let user pass the same mount twice.  TODO is to
include an error message widget and place the error
there instead of in the mountpoint widget value.

Signed-off-by: Ryan Harper <ryan.harper@canonical.com>

subiquity/models/blockdev.py

@@ -69,14 +69,14 @@ class Blockdev():
         self._parttype = parttype
         self.device = parted.getDevice(self.devpath)
         self.disk = parted.freshDisk(self.device, self.parttype)
-        self.mounts = {}
+        self._mounts = {}
         self.bcache = []
         self.lvm = []
 
     def reset(self):
         ''' Wipe out any actions queued for this disk '''
         self.disk = parted.freshDisk(self.device, self.parttype)
-        self.mounts = {}
+        self._mounts = {}
         self.bcache = []
         self.lvm = []
 
@@ -96,6 +96,10 @@ class Blockdev():
 
         return region
 
+    @property
+    def mounts(self):
+        return self._mounts.values()
+
     @property
     def parttype(self):
         return self._parttype
@@ -220,7 +224,7 @@ class Blockdev():
 
         # associate partition devpath with mountpoint
         if mountpoint:
-            self.mounts[partpath] = mountpoint
+            self._mounts[partpath] = mountpoint
 
     def get_actions(self):
         actions = []
@@ -243,7 +247,7 @@ class Blockdev():
                 format_action = FormatAction(partition_action,
                                              fs_type)
                 actions.append(format_action)
-                mountpoint = self.mounts.get(part.path)
+                mountpoint = self._mounts.get(part.path)
                 if mountpoint:
                     mount_action = MountAction(format_action, mountpoint)
                     actions.append(mount_action)
@@ -255,7 +259,7 @@ class Blockdev():
         fs_table = []
         for part in self.disk.partitions:
             if part.fileSystem:
-                mntpoint = self.mounts.get(part.path, part.fileSystem.type)
+                mntpoint = self._mounts.get(part.path, part.fileSystem.type)
                 fs_size = part.getSize(unit='B')
                 fs_type = part.fileSystem.type
                 devpath = part.path

subiquity/ui/interactive.py

@@ -36,6 +36,10 @@ class StringEditor(WidgetWrap):
     def value(self):
         return self._edit.get_edit_text()
 
+    @value.setter  # NOQA
+    def value(self, value):
+        self._edit.set_edit_text(value)
+ 
 
 class PasswordEditor(StringEditor):
     """ Password input prompt with masking

subiquity/ui/views/filesystem.py

@@ -81,7 +81,6 @@ class AddPartitionView(WidgetWrap):
             self._format_edit(),
             self.mountpoint
         ]
-
         return Pile(total_items)
 
     def cancel(self, button):
@@ -103,6 +102,18 @@ class AddPartitionView(WidgetWrap):
             "fstype": self.fstype.value,
             "mountpoint": self.mountpoint.value
         }
+        # Validate mountpoint input
+        if self.mountpoint.value in self.selected_disk.mounts:
+            log.error('provided mountpoint already allocated' +
+                      ' ({}'.format(self.mountpoint.value))
+            val = self.mountpoint.value
+            # FIXME: update the error message widget instead
+            self.mountpoint.value = 'ERROR: {} already mounted'.format(val)
+            self.signal.emit_signal(
+                'filesystem:add-disk-partiion',
+                self.selected_disk)
+            return
+        # Validate size (bytes) input
         if self.size.value == self.size_str:
             log.debug(
                 'User specified max value({}), fixing up: {} -> {}'.format(