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# Copyright 2012-2014 Canonical Ltd. This software is licensed under the
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# GNU Affero General Public License version 3 (see the file LICENSE).
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"""Install a pre-boot loader for TFTP download."""
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from __future__ import (
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from shutil import copyfile
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from provisioningserver.boot.tftppath import locate_tftp_path
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from provisioningserver.config import Config
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def make_destination(tftproot):
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"""Locate a loader's destination, creating the directory if needed.
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:param tftproot: The root directory served up by the TFTP server,
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e.g. /var/lib/maas/tftp/.
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:return: Full path describing the directory that the installed loader
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path = locate_tftp_path('', tftproot=tftproot)
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directory = os.path.dirname(path)
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if not os.path.isdir(directory):
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os.makedirs(directory)
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def are_identical_files(old, new):
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"""Are `old` and `new` identical?
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If `old` does not exist, the two are considered different (`new` is
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if os.path.isfile(old):
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return filecmp.cmp(old, new, shallow=False)
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def install_bootloader(loader, destination):
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"""Install bootloader file at path `loader` as `destination`.
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Installation will be atomic. If an identical loader is already
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installed, it will be left untouched.
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However it is still conceivable, depending on the TFTP implementation,
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that a download that is already in progress may suddenly start receiving
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data from the new file instead of the one it originally started
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:param loader: Name of loader to install.
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:param destination: Loader's intended filename, including full path,
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where it will become available over TFTP.
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if are_identical_files(destination, loader):
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# Copy new loader next to the old one, to ensure that it is on the
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# same filesystem. Once it is, we can replace the old one with an
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# atomic rename operation.
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temp_file = '%s.new' % destination
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if os.path.exists(temp_file):
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copyfile(loader, temp_file)
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os.rename(temp_file, destination)
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def add_arguments(parser):
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'--loader', dest='loader', default=None,
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help="Pre-boot loader to install.")
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"""Install a pre-boot loader into the TFTP directory structure.
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This won't overwrite an existing loader if its contents are unchanged.
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config = Config.load(args.config_file)
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tftproot = config["tftp"]["resource_root"]
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destination_path = make_destination(tftproot)
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destination = os.path.join(destination_path, os.path.basename(args.loader))
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install_bootloader(args.loader, destination)
added
removed
src/provisioningserver/boot/install_bootloader.py
