"""Helper functions for Logical Volume Manager (LVM) support."""
_LVM_LOCATION_PREFIX = "/lvm"
_LVM_LOCATION_PREFIX_LENGTH = len(_LVM_LOCATION_PREFIX)
[docs]
def LVMPathSpecGetVolumeIndex(path_spec):
"""Retrieves the volume index from the path specification.
Args:
path_spec (PathSpec): path specification.
Returns:
int: volume index or None if not available.
"""
volume_index = getattr(path_spec, "volume_index", None)
if volume_index is None:
location = getattr(path_spec, "location", None)
if location is None or not location.startswith(_LVM_LOCATION_PREFIX):
return None
volume_index = None
try:
volume_index = int(location[_LVM_LOCATION_PREFIX_LENGTH:], 10) - 1
except ValueError:
pass
if volume_index is None or volume_index < 0:
return None
return volume_index