Rework convert_scsi_path_to_hctl and convert_scsi_hctl_to_path

Do not check for type=disk, this is not a requirement.

Raise an RTSLibError if not found, rather than returning None.

Rework PSCSIStorageObject._configure to use the new semantics, and avoid
else clauses in try blocks, since they are confusing and not strictly
needed.

Properly qualify DeviceNotFoundError as pyudev.DeviceNotFoundError.

Signed-off-by: Andy Grover <agrover@redhat.com>

2 files changed, 23 insertions, 31 deletions

diff --git a/rtslib/tcm.py b/rtslib/tcm.py
index bdeafd2..2ea5d0f 100644
--- a/rtslib/tcm.py
+++ b/rtslib/tcm.py
@@ -313,11 +313,14 @@ class PSCSIStorageObject(StorageObject):
     def _configure(self, dev):
         self._check_self()
 
-        # Use H:C:T:L format or preserve the path given by the user.
+        # Use H:C:T:L format or use the path given by the user.
         try:
+            # assume 'dev' is the path, try to get h:c:t:l values
             (hostid, channelid, targetid, lunid) = \
                     convert_scsi_path_to_hctl(dev)
-        except TypeError:
+            udev_path = dev.strip()
+        except:
+            # Oops, maybe 'dev' is in h:c:t:l format, try to get udev_path
             try:
                 (hostid, channelid, targetid, lunid) = dev.split(':')
                 hostid = int(hostid)
@@ -329,15 +332,13 @@ class PSCSIStorageObject(StorageObject):
                                   + "path, and dev "
                                   + "parameter not in H:C:T:L "
                                   + "format: %s" % dev)
-            else:
-                udev_path = convert_scsi_hctl_to_path(hostid,
-                                                            channelid,
-                                                            targetid,
-                                                            lunid)
-            if not udev_path:
-                raise RTSLibError("SCSI device does not exist")
-        else:
-            udev_path = dev.strip()
+
+            udev_path = convert_scsi_hctl_to_path(hostid,
+                                                  channelid,
+                                                  targetid,
+                                                  lunid)
+
+        # -- now have all 5 values or have errored out --
 
         if is_dev_in_use(udev_path):
             raise RTSLibError("Cannot configure StorageObject because "
diff --git a/rtslib/utils.py b/rtslib/utils.py
index c9f8213..969d2d7 100644
--- a/rtslib/utils.py
+++ b/rtslib/utils.py
@@ -246,26 +246,15 @@ def convert_scsi_path_to_hctl(path):
     @param path: The udev path to the SCSI block device.
     @type path: string
     @return: An (host, controller, target, lun) tuple of integer
-    values representing the SCSI ID of the device, or None if no
-    match is found.
+    values representing the SCSI ID of the device, or raise RTSLibError.
     '''
     try:
         path = os.path.realpath(path)
         device = pyudev.Device.from_device_file(_CONTEXT, path)
-    except (pyudev.DeviceNotFoundError, EnvironmentError, ValueError):
-        return None
-
-    if device.device_type != u'disk':
-        return None
-
-    parent = device.find_parent(subsystem='scsi')
-    if parent is None:
-        return None
-
-    try:
+        parent = device.find_parent(subsystem='scsi')
         return [int(data) for data in parent.sys_name.split(':')]
-    except (ValueError, TypeError):
-        return None
+    except:
+        raise RTSLibError("Could not convert scsi path to hctl")
 
 def convert_scsi_hctl_to_path(host, controller, target, lun):
     '''
@@ -288,7 +277,7 @@ def convert_scsi_hctl_to_path(host, controller, target, lun):
     @type target: int
     @param lun: The SCSI Logical Unit Number.
     @type lun: int
-    @return: A string for the canonical path to the device, or empty string.
+    @return: A string for the canonical path to the device, or raise RTSLibError.
     '''
     try:
         host = int(host)
@@ -302,16 +291,18 @@ def convert_scsi_hctl_to_path(host, controller, target, lun):
     hctl = [host, controller, target, lun]
     try:
         scsi_device = pyudev.Device.from_name(_CONTEXT, 'scsi', ':'.join(hctl))
-    except DeviceNotFoundError:
-        return ''
+    except pyudev.DeviceNotFoundError:
+        raise RTSLibError("Could not find path for SCSI hctl")
 
     devices = _CONTEXT.list_devices(
        subsystem='block',
-       DEVTYPE='disk',
        parent=scsi_device
     )
 
-    return next((dev.device_node for dev in devices), '')
+    path = next((dev.device_node for dev in devices), '')
+    if path == None:
+        raise RTSLibError("Could not find path for SCSI hctl")
+    return path
 
 def generate_wwn(wwn_type):
     '''