def WritePidFile(pidfile):
"""Write the current process pidfile.
@type pidfile: string
@param pidfile: the path to the file to be written
@raise errors.LockError: if the pid file already exists and
points to a live process
@rtype: int
@return: the file descriptor of the lock file; do not close this unless
you want to unlock the pid file
"""
# We don't rename nor truncate the file to not drop locks under
# existing processes
fd_pidfile = os.open(pidfile, os.O_RDWR | os.O_CREAT, 0o600)
# Lock the PID file (and fail if not possible to do so). Any code
# wanting to send a signal to the daemon should try to lock the PID
# file before reading it. If acquiring the lock succeeds, the daemon is
# no longer running and the signal should not be sent.
try:
filelock.LockFile(fd_pidfile)
except errors.LockError:
msg = ["PID file '%s' is already locked by another process" % pidfile]
# Try to read PID file
pid = _ParsePidFileContents(os.read(fd_pidfile, 100))
if pid > 0:
msg.append(", PID read from file is %s" % pid)
raise errors.PidFileLockError("".join(msg))
os.write(fd_pidfile, "%d\n" % os.getpid())
return fd_pidfile
def ReadLockedPidFile(path):
"""Reads a locked PID file.
This can be used together with L{utils.process.StartDaemon}.
@type path: string
@param path: Path to PID file
@return: PID as integer or, if file was unlocked or couldn't be opened, None
"""
try:
fd = os.open(path, os.O_RDONLY)
except EnvironmentError as err:
if err.errno == errno.ENOENT:
# PID file doesn't exist
return None
raise
try:
try:
# Try to acquire lock
filelock.LockFile(fd)
except errors.LockError:
# Couldn't lock, daemon is running
return int(os.read(fd, 100))
finally:
os.close(fd)
return None
def SafeWriteFile(file_name, file_id, **kwargs):
"""Wraper over L{WriteFile} that locks the target file.
By keeping the target file locked during WriteFile, we ensure that
cooperating writers will safely serialise access to the file.
@type file_name: str
@param file_name: the target filename
@type file_id: tuple
@param file_id: a result from L{GetFileID}
"""
fd = os.open(file_name, os.O_RDONLY | os.O_CREAT)
try:
filelock.LockFile(fd)
if file_id is not None:
disk_id = GetFileID(fd=fd)
if not VerifyFileID(disk_id, file_id):
raise errors.LockError(
"Cannot overwrite file %s, it has been modified"
" since last written" % file_name)
return WriteFile(file_name, **kwargs)
finally:
os.close(fd)
@param path: Path to PID file
@return: PID as integer or, if file was unlocked or couldn't be opened, None
"""
try:
fd = os.open(path, os.O_RDONLY)
except EnvironmentError, err:
if err.errno == errno.ENOENT:
# PID file doesn't exist
return None
raise
try:
try:
# Try to acquire lock
filelock.LockFile(fd)
except errors.LockError:
# Couldn't lock, daemon is running
return int(os.read(fd, 100))
finally:
os.close(fd)
return None
def _SplitSshKey(key):
"""Splits a line for SSH's C{authorized_keys} file.
If the line has no options (e.g. no C{command="..."}), only the significant
parts, the key type and its hash, are used. Otherwise the whole line is used
(split at whitespace).
