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'''
umount.py - this file is part of S3QL (http://s3ql.googlecode.com)
Copyright (C) 2008-2009 Nikolaus Rath <Nikolaus@rath.org>
This program can be distributed under the terms of the GNU GPLv3.
'''
from __future__ import division, print_function, absolute_import
from .common import CTRL_NAME, QuietError, setup_logging
from .parse_args import ArgumentParser
import llfuse
import logging
import os
import posixpath
import subprocess
import sys
import textwrap
import time
log = logging.getLogger("umount")
def parse_args(args):
'''Parse command line
This function writes to stdout/stderr and may call `system.exit()` instead
of throwing an exception if it encounters errors.
'''
parser = ArgumentParser(
description=textwrap.dedent('''\
Unmounts an S3QL file system. The command returns only after all data
has been uploaded to the backend.'''))
parser.add_debug()
parser.add_quiet()
parser.add_version()
parser.add_argument("mountpoint", metavar='<mountpoint>',
type=(lambda x: x.rstrip('/')),
help='Mount point to un-mount')
parser.add_argument('--lazy', "-z", action="store_true", default=False,
help="Lazy umount. Detaches the file system immediately, even if there "
'are still open files. The data will be uploaded in the background '
'once all open files have been closed.')
return parser.parse_args(args)
def main(args=None):
'''Umount S3QL file system
This function writes to stdout/stderr and calls `system.exit()` instead
of returning.
'''
if args is None:
args = sys.argv[1:]
options = parse_args(args)
setup_logging(options)
mountpoint = options.mountpoint
# Check if it's a mount point
if not posixpath.ismount(mountpoint):
print('Not a mount point.', file=sys.stderr)
sys.exit(1)
# Check if it's an S3QL mountpoint
ctrlfile = os.path.join(mountpoint, CTRL_NAME)
if not (CTRL_NAME not in llfuse.listdir(mountpoint)
and os.path.exists(ctrlfile)):
print('Not an S3QL file system.', file=sys.stderr)
sys.exit(1)
if options.lazy:
lazy_umount(mountpoint)
else:
blocking_umount(mountpoint)
def lazy_umount(mountpoint):
'''Invoke fusermount -u -z for mountpoint
This function writes to stdout/stderr and calls `system.exit()`.
'''
if os.getuid() == 0:
umount_cmd = ('umount', '-l', mountpoint)
else:
umount_cmd = ('fusermount', '-u', '-z', mountpoint)
if not subprocess.call(umount_cmd) == 0:
sys.exit(1)
def blocking_umount(mountpoint):
'''Invoke fusermount and wait for daemon to terminate.
This function writes to stdout/stderr and calls `system.exit()`.
'''
devnull = open('/dev/null', 'wb')
if subprocess.call(['fuser', '-m', mountpoint], stdout=devnull,
stderr=devnull) == 0:
print('Cannot unmount, the following processes still access the mountpoint:')
subprocess.call(['fuser', '-v', '-m', mountpoint], stdout=sys.stdout,
stderr=sys.stdout)
raise QuietError()
ctrlfile = os.path.join(mountpoint, CTRL_NAME)
log.debug('Flushing cache...')
llfuse.setxattr(ctrlfile, b's3ql_flushcache!', b'dummy')
# Get pid
log.debug('Trying to get pid')
pid = int(llfuse.getxattr(ctrlfile, b's3ql_pid?'))
log.debug('PID is %d', pid)
# Get command line to make race conditions less-likely
with open('/proc/%d/cmdline' % pid, 'r') as fh:
cmdline = fh.readline()
log.debug('cmdline is %r', cmdline)
# Unmount
log.debug('Unmounting...')
# This seems to be necessary to prevent weird busy errors
time.sleep(3)
if os.getuid() == 0:
umount_cmd = ['umount', mountpoint]
else:
umount_cmd = ['fusermount', '-u', mountpoint]
if subprocess.call(umount_cmd) != 0:
sys.exit(1)
# Wait for daemon
log.debug('Uploading metadata...')
step = 0.5
while True:
try:
os.kill(pid, 0)
except OSError:
log.debug('Kill failed, assuming daemon has quit.')
break
# Check that the process did not terminate and the PID
# was reused by a different process
try:
with open('/proc/%d/cmdline' % pid, 'r') as fh:
if fh.readline() != cmdline:
log.debug('PID still alive, but cmdline changed')
# PID must have been reused, original process terminated
break
else:
log.debug('PID still alive and commandline unchanged.')
except OSError:
# Process must have exited by now
log.debug('Reading cmdline failed, assuming daemon has quit.')
break
# Process still exists, we wait
log.debug('Daemon seems to be alive, waiting...')
time.sleep(step)
if step < 10:
step *= 2
if __name__ == '__main__':
main(sys.argv[1:])
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