/usr/share/pyshared/landscape/lib/lock.py is in landscape-common 12.04.3-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 | import fcntl
import time
import os
class LockError(Exception):
"""Raised when unable to lock a file."""
def lock_path(path, timeout=0):
fd = os.open(path, os.O_CREAT)
flags = fcntl.fcntl(fd, fcntl.F_GETFD, 0)
flags |= fcntl.FD_CLOEXEC
fcntl.fcntl(fd, fcntl.F_SETFD, flags)
started = time.time()
while True:
try:
fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
except IOError:
if started < time.time() - timeout:
raise LockError("Couldn't obtain lock")
else:
break
time.sleep(0.1)
def unlock_path():
fcntl.flock(fd, fcntl.LOCK_UN)
os.close(fd)
return unlock_path
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