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'''
umount.py - this file is part of S3QL.
Copyright © 2008 Nikolaus Rath <Nikolaus@rath.org>
This work can be distributed under the terms of the GNU GPLv3.
'''
from .logging import logging, setup_logging
from . import CTRL_NAME
from .common import assert_s3ql_mountpoint, parse_literal
from .parse_args import ArgumentParser
import llfuse
import os
import subprocess
import platform
import sys
import textwrap
import time
log = logging.getLogger(__name__)
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)
class UmountError(Exception):
"""
Base class for unmount errors.
"""
message = 'internal error'
exitcode = 3
def __init__(self, mountpoint):
super().__init__()
self.mountpoint = mountpoint
def __str__(self):
return self.message
class UmountSubError(UmountError):
message = 'Unmount subprocess failed.'
exitcode = 2
class MountInUseError(UmountError):
message = 'In use.'
exitcode = 1
def lazy_umount(mountpoint):
'''Invoke fusermount -u -z for mountpoint'''
if os.getuid() == 0 or platform.system() == 'Darwin':
# MacOS X always uses umount rather than fusermount
umount_cmd = ('umount', '-l', mountpoint)
else:
umount_cmd = ('fusermount', '-u', '-z', mountpoint)
if subprocess.call(umount_cmd) != 0:
raise UmountSubError(mountpoint)
def get_cmdline(pid):
'''Return command line for *pid*
If *pid* doesn't exists, return None. If command line
cannot be determined for other reasons, log warning
and return None.
'''
try:
output = subprocess.check_output(['ps', '-p', str(pid), '-o', 'args='],
universal_newlines=True).strip()
except subprocess.CalledProcessError:
log.warning('Unable to execute ps, assuming process %d has terminated.'
% pid)
return None
if output:
return output
else:
return None
def blocking_umount(mountpoint):
'''Invoke fusermount and wait for daemon to terminate.'''
with open('/dev/null', 'wb') as devnull:
if subprocess.call(['fuser', '-m', mountpoint], stdout=devnull,
stderr=devnull) == 0:
raise MountInUseError(mountpoint)
ctrlfile = os.path.join(mountpoint, CTRL_NAME)
log.debug('Flushing cache...')
llfuse.setxattr(ctrlfile, 's3ql_flushcache!', b'dummy')
# Get pid
log.debug('Trying to get pid')
pid = parse_literal(llfuse.getxattr(ctrlfile, 's3ql_pid?'), int)
log.debug('PID is %d', pid)
# Get command line to make race conditions less-likely
cmdline = get_cmdline(pid)
# Unmount
log.debug('Unmounting...')
if os.getuid() == 0 or platform.system() == 'Darwin':
# MacOS X always uses umount rather than fusermount
umount_cmd = ['umount', mountpoint]
else:
umount_cmd = ['fusermount', '-u', mountpoint]
if subprocess.call(umount_cmd) != 0:
raise UmountSubError(mountpoint)
# Wait for daemon
log.debug('Uploading metadata...')
step = 0.1
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
cmdline2 = get_cmdline(pid)
if cmdline2 is None:
log.debug('Reading cmdline failed, assuming daemon has quit.')
break
elif cmdline2 == cmdline:
log.debug('PID still alive and commandline unchanged.')
else:
log.debug('PID still alive, but cmdline changed')
break
# Process still exists, we wait
log.debug('Daemon seems to be alive, waiting...')
time.sleep(step)
if step < 1:
step += 0.1
def main(args=None):
'''Umount S3QL file system'''
if args is None:
args = sys.argv[1:]
options = parse_args(args)
setup_logging(options)
assert_s3ql_mountpoint(options.mountpoint)
try:
if options.lazy:
lazy_umount(options.mountpoint)
else:
blocking_umount(options.mountpoint)
except MountInUseError as err:
print('Cannot unmount, the following processes still access the mountpoint:',
file=sys.stderr)
subprocess.call(['fuser', '-v', '-m', options.mountpoint],
stdout=sys.stderr, stderr=sys.stderr)
sys.exit(err.exitcode)
except UmountError as err:
print('%s: %s' % (options.mountpoint, err), file=sys.stderr)
sys.exit(err.exitcode)
sys.exit(0)
if __name__ == '__main__':
main(sys.argv[1:])
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