drive = ['C:','Z:']

threshold = ['5GB','100MB']


import sys
import os
import re
import ctypes

class disable_file_system_redirection:
    _disable = ctypes.windll.kernel32.Wow64DisableWow64FsRedirection
    _revert = ctypes.windll.kernel32.Wow64RevertWow64FsRedirection
    def __enter__(self):
        self.old_value = ctypes.c_long()
        self.success = self._disable(ctypes.byref(self.old_value))
    def __exit__(self, type, value, traceback):
        if self.success:
            self._revert(self.old_value)

def alert(arg):
    sys.stderr.write("%d%d%d" % (arg, arg, arg))

def convert_bytes(size, unit=None):
    if unit == "KB":
        return (round(size / 1024, 3))
    elif unit == "MB":
        return (round(size / (1024 * 1024), 3))
    elif unit == "GB":
        return (round(size / (1024 * 1024 * 1024), 3))


p = 0  # This constant contains result which will be transferred into the alert return value 

drives = list(zip(drive,threshold))

with disable_file_system_redirection():
    for dv,s in drives:
        cmd = os.popen('fsutil volume diskfree '+dv).read().strip()
        free_space = re.findall('Total free bytes(.*)',cmd)
        d = "".join((free_space[0].split()[1].split(',')))
        i = float(d)
        if 'KB' in s:
            threshold_size = float(s.replace("KB",""))
            Existing_FS = convert_bytes(i,"KB")
        elif 'MB' in s:
            threshold_size = float(s.replace("MB",""))
            Existing_FS = convert_bytes(i,"MB")
        elif 'GB' in s:
            threshold_size = float(s.replace("GB",""))
            Existing_FS = convert_bytes(i,"GB")

        if Existing_FS < threshold_size:
            print("Low storage alert in local disk "+dv)
            p = 1
        else:
            pass

if p:
    alert(1)
else:
    alert(0)