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import contextlib
from cloudinit import util
class MountFailedError(Exception):
pass
@contextlib.contextmanager
def unmounter(umount):
try:
yield umount
finally:
if umount:
sh.subp(["umount", '-l', umount])
def mount_callback_umount(device, callback, data=None):
"""
mount the device, call method 'callback' passing the directory
in which it was mounted, then unmount. Return whatever 'callback'
returned. If data != None, also pass data to callback.
"""
# go through mounts to see if it was already mounted
mounts = sh.load_file("/proc/mounts").splitlines()
mounted = {}
for mpline in mounts:
(dev, mp, fstype, _opts, _freq, _passno) = mpline.split()
mp = mp.replace("\\040", " ")
mounted[dev] = (dev, fstype, mp, False)
with util.tempdir() as tmpd:
umount = False
if device in mounted:
mountpoint = "%s/" % mounted[device][2]
else:
try:
mountcmd = ["mount", "-o", "ro", device, tmpd]
util.subp(mountcmd)
umount = tmpd
except IOError as exc:
raise MountFailedError("%s" % (exc))
mountpoint = "%s/" % tmpd
with unmounter(umount):
if data is None:
ret = callback(mountpoint)
else:
ret = callback(mountpoint, data)
return ret
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