/usr/lib/python2.7/dist-packages/provisioningserver/boot/install_bootloader.py is in python-maas-provisioningserver 1.5.4+bzr2294-0ubuntu1.2.
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 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 | # Copyright 2012-2014 Canonical Ltd. This software is licensed under the
# GNU Affero General Public License version 3 (see the file LICENSE).
"""Install a pre-boot loader for TFTP download."""
from __future__ import (
absolute_import,
print_function,
unicode_literals,
)
str = None
__metaclass__ = type
__all__ = [
"install_bootloader",
"make_destination",
]
import filecmp
import os.path
from shutil import copyfile
from provisioningserver.boot.tftppath import locate_tftp_path
def make_destination(tftproot):
"""Locate a loader's destination, creating the directory if needed.
:param tftproot: The root directory served up by the TFTP server,
e.g. /var/lib/maas/tftp/.
:return: Full path describing the directory that the installed loader
should end up having.
"""
path = locate_tftp_path('', tftproot=tftproot)
directory = os.path.dirname(path)
if not os.path.isdir(directory):
os.makedirs(directory)
return directory
def are_identical_files(old, new):
"""Are `old` and `new` identical?
If `old` does not exist, the two are considered different (`new` is
assumed to exist).
"""
if os.path.isfile(old):
return filecmp.cmp(old, new, shallow=False)
else:
return False
def install_bootloader(loader, destination):
"""Install bootloader file at path `loader` as `destination`.
Installation will be atomic. If an identical loader is already
installed, it will be left untouched.
However it is still conceivable, depending on the TFTP implementation,
that a download that is already in progress may suddenly start receiving
data from the new file instead of the one it originally started
downloading.
:param loader: Name of loader to install.
:param destination: Loader's intended filename, including full path,
where it will become available over TFTP.
"""
if are_identical_files(destination, loader):
return
# Copy new loader next to the old one, to ensure that it is on the
# same filesystem. Once it is, we can replace the old one with an
# atomic rename operation.
temp_file = '%s.new' % destination
if os.path.exists(temp_file):
os.remove(temp_file)
copyfile(loader, temp_file)
os.rename(temp_file, destination)
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