devicedisk: Rename path_exists -> path_definitely_exists

Since it's a best effort attempt, try to make it more clear that
we aren't certain if paths exist in some cases.

virtManager/addstorage.py

@@ -267,7 +267,7 @@ class vmmAddStorage(vmmGObjectUI):
         do_exist = False
         ret = True
         try:
-            do_exist = virtinst.VirtualDisk.path_exists(conn, ideal)
+            do_exist = virtinst.VirtualDisk.path_definitely_exists(conn, ideal)
             ret = virtinst.VirtualDisk.path_in_use_by(conn, ideal)
         except:
             logging.exception("Error checking default path usage")

virtManager/clone.py

@@ -701,8 +701,8 @@ class vmmCloneVM(vmmGObjectUI):
 
         new_path = self.widget("change-storage-new").get_text()
 
-        if virtinst.VirtualDisk.path_exists(self.clone_design.conn,
-                                            new_path):
+        if virtinst.VirtualDisk.path_definitely_exists(self.clone_design.conn,
+                                                       new_path):
             res = self.err.yes_no(_("Cloning will overwrite the existing "
                                     "file"),
                                     _("Using an existing image will overwrite "

virtManager/connection.py

@@ -554,7 +554,8 @@ class vmmConnection(vmmGObject):
 
     def get_vol_by_path(self, path):
         # path_exists will handle stuff like refreshing a busted pool
-        if not virtinst.VirtualDisk.path_exists(self.get_backend(), path):
+        if not virtinst.VirtualDisk.path_definitely_exists(self.get_backend(),
+                                                           path):
             return None
 
         for pool in self._pools.values():

virtManager/details.py

@@ -2621,7 +2621,8 @@ class vmmDetails(vmmGObjectUI):
         iotune_wis = (disk.iotune_wis or 0)
 
         show_format = (not self.is_customize_dialog or
-                       disk.path_exists(disk.conn, disk.path))
+                       virtinst.VirtualDisk.path_definitely_exists(
+                            disk.conn, disk.path))
 
         size = _("Unknown")
         if not path:

virtinst/cli.py

@@ -329,7 +329,7 @@ def validate_disk(dev, warn_overwrite=False):
         """
         if not warn_overwrite:
             return
-        if VirtualDisk.path_exists(dev.conn, dev.path):
+        if VirtualDisk.path_definitely_exists(dev.conn, dev.path):
             _optional_fail(
                 _("This will overwrite the existing path '%s'" % dev.path))
 

virtinst/cloner.py

@@ -476,7 +476,7 @@ class Cloner(object):
         clonebase = os.path.join(dirname, clonebase)
         return util.generate_name(
                     clonebase,
-                    lambda p: VirtualDisk.path_exists(self.conn, p),
+                    lambda p: VirtualDisk.path_definitely_exists(self.conn, p),
                     suffix,
                     lib_collision=False)
 

virtinst/devicedisk.py

@@ -212,9 +212,17 @@ class VirtualDisk(VirtualDevice):
         return bus
 
     @staticmethod
-    def path_exists(conn, path):
+    def path_definitely_exists(conn, path):
         """
-        Check if path exists. If we can't determine, return False
+        Check if path exists.
+
+        return True if we are certain, False otherwise. Path may in fact
+        exist if we return False, but we can't exhaustively know in all
+        cases.
+
+        (In fact if cached storage volume data is out of date, the volume
+         may have disappeared behind out back, but that shouldn't have bad
+         effects in practice.)
         """
         if path is None:
             return False