glob, pathlib, and errno

from glob import glob
from pathlib import Path
import errno

def pinmux_path( name ):
    paths = glob( '/sys/bus/platform/drivers/bone-pinmux-helper/*%s*/state' % name )
    if len(paths) == 0:
        raise KeyError( 'Pinmux node not found: ' + name )
    if len(paths) > 1:
        raise KeyError( 'Pinmux node ambiguous: ' + name )
    return Path( paths[0] )

def get_pinmux_state( name ):
    return pinmux_path( name ).read_text().rstrip()

def set_pinmux_state( name, state ):
    try:
        pinmux_path( name ).write_text( state )
    except OSError as err:
        if err.errno == errno.ENODEV:
            raise ValueError( 'Invalid state for ' + name + ': ' + state ) from None
        else:
            raise