fkumount

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# License: GPLv3 or higher

import datetime, getopt, os, signal, subprocess, sys, threading, time

# python 3: determine locale encoding
#           (needed for some string handling later on)
if sys.version_info[0] >= 3:
	import locale
	encoding_to_use = locale.getpreferredencoding()

#****************************************************************************
# Command line parsing
#     We accept the same -R option as start-stop-daemon for killing
#     processes.
#****************************************************************************

def usage():
	sys.stdout.write("Usage: %s [-R schedule] path [path2 [path3 ...]]\n" % sys.argv[0])
	sys.stdout.write("Forcibly Umount one or more paths by Killing processes still accessing them.\n")
	sys.stdout.write("       (See man start-stop-daemon for details on -R option.\n")
	sys.stdout.write("        Defaults to: TERM/10/TERM/10/TERM/10/KILL/5/KILL/5.)\n")

def is_integer(s):
	try:
		int(s)
		return True
	except ValueError:
		return False

try:
	opts, args = getopt.getopt(sys.argv[1:], "hR:", ["help", "retry="])
except getopt.GetoptError as err:
	sys.stderr.write("%s: %s\n" % (sys.argv[0], str(err)))
	usage()
	sys.exit(2)

retryspec="TERM/10/TERM/10/TERM/10/KILL/5/KILL/5"

for opt, arg in opts:
	if opt in ("-R", "--retry"):
		retryspec = arg
	elif opt in ("-h", "--help"):
		usage()
		sys.exit()
	else:
		assert False, "unhandled option"

if is_integer(retryspec):
	retryspec = "TERM/%d/TERM/%d/TERM/%d/KILL/%s/KILL/%s" % (int((int(retryspec) + 1)/3), int((int(retryspec) + 1)/3), int(int(retryspec)/3), int((int(retryspec) + 1)/2), int(int(retryspec)/2))

retryspec = retryspec.split("/")
if len(retryspec) % 2 != 0:
	sys.stderr.write("%s: Invalid retry option %s specified.\n" % (sys.argv[0], "/".join(retryspec)))
	sys.exit(2)

retries = []
for i in range(int(len(retryspec) / 2)):
	try:
		sig = retryspec[2 * i]
		if retryspec[2 * i + 1] == "forever":
			timeout = -1
		else:
			timeout = int(retryspec[2 * i + 1])
			if timeout <= 0:
				raise ValueError
	except ValueError:
		sys.stderr.write("%s: Invalid timeout %s specified.\n" % (sys.argv[0], retryspec[2 * i + 1]))
		sys.exit(2)
	if sig[0] == "-" and is_integer(sig[1:]):
		sig = int(sig[1:])
	else:
		if sig[0] == "-":
			sig = sig[1:]
		try:
			sig = signal.__dict__["SIG%s" % sig]
		except KeyError:
			sys.stderr.write("%s: Invalid signal %s specified.\n" % (sys.argv[0], retryspec[2 * i]))
			sys.exit(2)
	retries.append((sig, timeout))

# lookup paths relative to current dir, so relative paths are allowed
mpoints = []
for arg in args:
	mpoint = os.path.realpath(arg)
	if not os.path.exists(arg):
		sys.stderr.write("%s: Skipping non-existing mount point %s.\n" % (sys.argv[0], arg));
		continue
	if mpoint == "/":
		sys.stderr.write("%s: Skipping mount point %s that is equivalent to /.\n" % (sys.argv[0], arg))
		continue
	mpoints.append(mpoint)

if not len(mpoints):
	sys.stderr.write("%s: No mountpoints specified.\n" % (sys.argv[0]))
	sys.exit(2)

#****************************************************************************
# Actual umounting logic
#    retries now contains a list of tuples with signal and timeout of
#    how to kill processes if umount doesn't immediately work
#****************************************************************************

# don't be part of the problem, get out of the way
os.chdir("/")

def run(cmd):
	p = subprocess.Popen(cmd, stdin=open("/dev/null","r"), stdout=subprocess.PIPE, stderr=subprocess.PIPE)
	out, err = p.communicate()
	# python 3: convert output to str type (which is unicode in python3)
	if sys.version_info[0] >= 3:
		out = out.decode(encoding_to_use, errors='replace')
		err = err.decode(encoding_to_use, errors='replace')
	return (p.returncode, out, err)

# See if mount point is mounted
def is_mounted(mpoint):
	rc, out, err = run(["mountpoint", "-q", "%s/" % mpoint])
	return rc == 0

# Kill a list of processes
def killprocs(procs, sig):
	for proc in procs:
		try:
			os.kill(int(proc), int(sig))
		except OSError:
			# OSError: process may already be dead
			pass
		except ValueError:
			# ValueError: conversion error, shouldn't happen,
			#             but we don't care...
			pass

# This does the actual umounting for a single mount point
def do_umount(mpoint, retries,rcs,):
	if not is_mounted(mpoint):
		sys.stderr.write("%s: %s is not mounted\n" % (sys.argv[0], mpoint))
		return

	rc, umount_out, umount_err = run(["umount", "%s/" % mpoint])
	if rc == 0:
		# Success on first try, yay!
		return

	# Check if umount worked anyway (rc is not necessarily 0...)
	if not is_mounted(mpoint):
		return

	# Well, no we'll have to kill processes
	for sig, timeout in retries:
		# Get a list of processes
		rc, lsof_out, lsof_err = run(["lsof", "-t", "+f", "--", "%s/" % mpoint])
		# list() required in python 3 since filter() is only
		# a generator object that cannot be rewound
		procs = list(filter(None, lsof_out.split("\n")))

		# Kill'em
		if (sig == signal.SIGKILL):
			# first stop all processes so they can't spawn new ones
			# before getting killed
			killprocs(procs, signal.SIGSTOP)
			killprocs(procs, signal.SIGKILL)
			killprocs(procs, signal.SIGCONT)
		else:
			killprocs(procs, sig)

		# Try to umount until timoeut reached
		abort_when = datetime.datetime.now() + datetime.timedelta(seconds=timeout)
		while timeout < 0 or datetime.datetime.now() < abort_when:
			rc, umount_out, umount_err = run(["umount", "%s/" % mpoint])
			if rc == 0 or not is_mounted(mpoint):
				return
			time.sleep(1)

	# Oooops, something went wrong...
	msg = "%s: failed to umount %s; last output and error messages from umount:\n" % (sys.argv[0], mpoint)
	if len(umount_out.strip()) > 0:
		msg += "%s\n" % umount_out.strip()
	if len(umount_err.strip()) > 0:
		msg += "%s\n" % umount_err.strip()
	sys.stderr.write(msg)
	rcs.append(1)

# umount everything in parallel
threads = []
rcs = []
for mpoint in mpoints:
	thread = threading.Thread(target=do_umount, args=(mpoint,retries,rcs,))
	threads.append(thread)
	thread.start()

# collect them all
for thread in threads:
	thread.join()

# some error happened
if len(rcs):
	sys.exit(1)