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Diffstat (limited to 'image-bundle/block_disk.py')
| -rwxr-xr-x | image-bundle/block_disk.py | 227 |
1 files changed, 227 insertions, 0 deletions
diff --git a/image-bundle/block_disk.py b/image-bundle/block_disk.py new file mode 100755 index 0000000..08c156e --- /dev/null +++ b/image-bundle/block_disk.py @@ -0,0 +1,227 @@ +#!/usr/bin/python +# Copyright 2013 Google Inc. All Rights Reserved. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +"""Module to create raw disk images. + +Stores a copy of directories/files in a file mounted as a partitioned blocked +device. +""" + + + +import hashlib +import logging +import os +import re +import tempfile + +import exclude_spec +import fs_copy +import utils + + +class RawDiskError(Exception): + """Error occured during raw disk creation.""" + + +class InvalidRawDiskError(Exception): + """Error when verification fails before copying.""" + + +class FsRawDisk(fs_copy.FsCopy): + """Creates a raw disk copy of OS image and bundles it into gzipped tar.""" + + def __init__(self, fs_size): + """Constructor for FsRawDisk class. + + Args: + fs_size: Size of the raw disk. + """ + super(FsRawDisk, self).__init__() + self._fs_size = fs_size + + def Bundleup(self): + """Creates a raw disk copy of OS image and bundles it into gzipped tar. + + Returns: + A size of a generated raw disk and the SHA1 digest of the the tar archive. + + Raises: + RawDiskError: If number of partitions in a created image doesn't match + expected count. + """ + self._Verify() + # Create sparse file with specified size + file_path = os.path.join(self._scratch_dir, 'disk.raw') + self._excludes.append(exclude_spec.ExcludeSpec(file_path)) + with open(file_path, 'wb') as disk_file: + disk_file.truncate(self._fs_size) + utils.MakePartitionTable(file_path) + # Pass 1MB as start to avoid 'Warning: The resulting partition is not + # properly aligned for best performance.' from parted. + utils.MakePartition(file_path, 'primary', 'ext2', 1024 * 1024, + self._fs_size) + with utils.LoadDiskImage(file_path) as devices: + # For now we only support disks with a single partition. + if len(devices) != 1: + raise RawDiskError(devices) + uuid = utils.MakeFileSystem(devices[0], 'ext4') + if uuid is None: + raise Exception('Could not get uuid from makefilesystem') + mount_point = tempfile.mkdtemp(dir=self._scratch_dir) + with utils.MountFileSystem(devices[0], mount_point): + self._CopySourceFiles(mount_point) + self._CopyPlatformSpecialFiles(mount_point) + self._ProcessOverwriteList(mount_point) + self._CleanupNetwork(mount_point) + self._UpdateFstab(mount_point, uuid) + + utils.TarAndGzipFile(file_path, self._output_tarfile) + os.remove(file_path) + # TODO(user): It would be better to compute tar.gz file hash during + # archiving. + h = hashlib.sha1() + with open(self._output_tarfile, 'rb') as tar_file: + for chunk in iter(lambda: tar_file.read(8192), ''): + h.update(chunk) + return (self._fs_size, h.hexdigest()) + + def _CopySourceFiles(self, mount_point): + """Copies all source files/directories to a mounted raw disk. + + There are several cases which must be handled separately: + 1. src=dir1 and dest is empty. In this case we simply copy the content of + dir1 to mount_point. + 2. src=dir1 and dest=dir2. In this case dir1 is copied to mount_point + under a new name dir2, so its content would be copied under + mount_point/dir2. + 3. src=file1/dir1 and dest=file2/dir2 and is_recursive=False. file1/dir1 + is copied to mount_point/file2 or mount_point/dir2. + + Args: + mount_point: A path to a mounted raw disk. + """ + for (src, dest, is_recursive) in self._srcs: + # Generate a list of files/directories excluded from copying to raw disk. + # rsync expects them to be relative to src directory so we need to + # regenerate this list for every src separately. + with tempfile.NamedTemporaryFile(dir=self._scratch_dir) as rsync_file: + for spec in self._excludes: + rsync_file.write(spec.GetRsyncSpec(src)) + + # make sure that rsync utility sees all the content of rsync_file which + # otherwise can be buffered. + rsync_file.flush() + if is_recursive: + # if a directory ends with / rsync copies the content of a + # directory, otherwise it also copies the directory itself. + src = src.rstrip('/') + if not dest: + src += '/' + utils.Rsync(src, mount_point, rsync_file.name, + self._ignore_hard_links, recursive=True) + if dest: + os.rename(os.path.join(mount_point, os.path.basename(src)), + os.path.join(mount_point, dest)) + else: + utils.Rsync(src, os.path.join(mount_point, dest), rsync_file.name, + self._ignore_hard_links, recursive=False) + + def _CopyPlatformSpecialFiles(self, mount_point): + """Copies platform special files to a mounted raw disk. + + Args: + mount_point: A path to a mounted raw disk. + """ + if self._platform: + special_files = self._platform.GetPlatformSpecialFiles(self._scratch_dir) + for (src, dest) in special_files: + utils.Rsync(src, os.path.join(mount_point, dest), None, + self._ignore_hard_links, recursive=False) + + def _ProcessOverwriteList(self, mount_point): + """Overwrites a set of files/directories requested by platform. + + Args: + mount_point: A path to a mounted raw disk. + """ + for file_name in self._overwrite_list: + file_path = os.path.join(mount_point, file_name) + if os.path.exists(file_path): + if os.path.isdir(file_path): + # TODO(user): platform.Overwrite is expected to overwrite the + # directory in place from what I can tell. In case of a file it will + # create a new file which must be copied to mounted raw disk. So there + # some inconsistency which would need to be addresses if and when we + # encounter a platform which would want to overwrite a directory. + self._platform.Overwrite(file_path, file_name, self._scratch_dir) + logging.info('rawdisk: modifying directory %s', file_path) + else: + new_file = self._platform.Overwrite(file_path, file_name, + self._scratch_dir) + logging.info('rawdisk: modifying %s from %s', file_path, new_file) + utils.Rsync(new_file, file_path, None, self._ignore_hard_links, + recursive=False) + + + def _CleanupNetwork(self, mount_point): + """Remove any record of our current MAC address.""" + net_rules_path = os.path.join( + mount_point, + 'lib/udev/rules.d/75-persistent-net-generator.rules') + if os.path.exists(net_rules_path): + os.remove(net_rules_path) + + def _UpdateFstab(self, mount_point, uuid): + """Update /etc/fstab with the new root fs UUID.""" + fstab_path = os.path.join(mount_point, 'etc/fstab') + if not os.path.exists(fstab_path): + print 'etc/fstab does not exist. Not updating fstab uuid' + return + + f = open(fstab_path, 'r') + lines = f.readlines() + f.close() + + def UpdateUUID(line): + """Replace the UUID on the entry for /.""" + g = re.match(r'UUID=\S+\s+/\s+(.*)', line) + if not g: + return line + return 'UUID=%s / %s\n' % (uuid, g.group(1)) + + lines = map(UpdateUUID, lines) + f = open(fstab_path, 'w') + f.write(''.join(lines)) + f.close() + + +class RootFsRaw(FsRawDisk): + """Block disk copy of the root file system. + + Takes care of additional checks for a root file system. + """ + + def __init__(self, fs_size): + super(RootFsRaw, self).__init__(fs_size) + + def _Verify(self): + super(RootFsRaw, self)._Verify() + # exactly one file system to bundle up + if len(self._srcs) != 1: + raise InvalidRawDiskError('Root filesystems must have exactly one src.') + # check that destination field is empty. + if self._srcs[0][1]: + raise InvalidRawDiskError('Root filesystems must be copied as /') |