X-Git-Url: https://code.grnet.gr/git/snf-image-creator/blobdiff_plain/0d5a999d07ff022fecf74cc5e7e2d572d323adce..0144d7c741cb742f52ef8755fc315afaa7ea4747:/image_creator/disk.py diff --git a/image_creator/disk.py b/image_creator/disk.py index b220dff..6b69aad 100644 --- a/image_creator/disk.py +++ b/image_creator/disk.py @@ -1,6 +1,40 @@ -#!/usr/bin/env python +# Copyright 2012 GRNET S.A. All rights reserved. +# +# Redistribution and use in source and binary forms, with or +# without modification, are permitted provided that the following +# conditions are met: +# +# 1. Redistributions of source code must retain the above +# copyright notice, this list of conditions and the following +# disclaimer. +# +# 2. Redistributions in binary form must reproduce the above +# copyright notice, this list of conditions and the following +# disclaimer in the documentation and/or other materials +# provided with the distribution. +# +# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS +# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED +# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR +# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR +# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF +# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED +# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN +# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +# POSSIBILITY OF SUCH DAMAGE. +# +# The views and conclusions contained in the software and +# documentation are those of the authors and should not be +# interpreted as representing official policies, either expressed +# or implied, of GRNET S.A. + +from image_creator.util import get_command +from image_creator.util import warn, progress, success, output +from image_creator import FatalError -import losetup import stat import os import tempfile @@ -8,16 +42,30 @@ import uuid import re import sys import guestfs +import time +from sendfile import sendfile + + +class DiskError(Exception): + pass -from pbs import dmsetup -from pbs import blockdev -from pbs import dd +dd = get_command('dd') +dmsetup = get_command('dmsetup') +losetup = get_command('losetup') +blockdev = get_command('blockdev') -class DiskError(Exception): pass class Disk(object): + """This class represents a hard disk hosting an Operating System + + A Disk instance never alters the source media it is created from. + Any change is done on a snapshot created by the device-mapper of + the Linux kernel. + """ def __init__(self, source): + """Create a new Disk instance out of a source media. The source + media can be an image file, a block device or a directory.""" self._cleanup_jobs = [] self._devices = [] self.source = source @@ -26,39 +74,57 @@ class Disk(object): self._cleanup_jobs.append((job, args)) def _losetup(self, fname): - loop = losetup.find_unused_loop_device() - loop.mount(fname) - self._add_cleanup(loop.unmount) - return loop.device + loop = losetup('-f', '--show', fname) + loop = loop.strip() # remove the new-line char + self._add_cleanup(losetup, '-d', loop) + return loop def _dir_to_disk(self): raise NotImplementedError def cleanup(self): + """Cleanup internal data. This needs to be called before the + program ends. + """ while len(self._devices): device = self._devices.pop() device.destroy() - + while len(self._cleanup_jobs): job, args = self._cleanup_jobs.pop() job(*args) def get_device(self): + """Returns a newly created DiskDevice instance. + + This instance is a snapshot of the original source media of + the Disk instance. + """ + + output("Examining source media `%s'..." % self.source, False) sourcedev = self.source mode = os.stat(self.source).st_mode if stat.S_ISDIR(mode): + success('looks like a directory') return self._losetup(self._dir_to_disk()) elif stat.S_ISREG(mode): + success('looks like an image file') sourcedev = self._losetup(self.source) elif not stat.S_ISBLK(mode): - raise ValueError("Value for self.source is invalid") + raise ValueError("Invalid media source. Only block devices, " + "regular files and directories are supported.") + else: + success('looks like a block device') # Take a snapshot and return it to the user + output("Snapshotting media source...", False) size = blockdev('--getsize', sourcedev) cowfd, cow = tempfile.mkstemp() + os.close(cowfd) self._add_cleanup(os.unlink, cow) - # Create 1G cow file - dd('if=/dev/null', 'of=%s' % cow, 'bs=1k' ,'seek=%d' % (1024*1024)) + # Create 1G cow sparse file + dd('if=/dev/null', 'of=%s' % cow, 'bs=1k', \ + 'seek=%d' % (1024 * 1024)) cowdev = self._losetup(cow) snapshot = uuid.uuid4().hex @@ -68,59 +134,209 @@ class Disk(object): (int(size), sourcedev, cowdev)) dmsetup('create', snapshot, table) self._add_cleanup(dmsetup, 'remove', snapshot) + # Sometimes dmsetup remove fails with Device or resource busy, + # although everything is cleaned up and the snapshot is not + # used by anyone. Add a 2 seconds delay to be on the safe side. + self._add_cleanup(time.sleep, 2) + finally: os.unlink(table) - + success('done') new_device = DiskDevice("/dev/mapper/%s" % snapshot) self._devices.append(new_device) + new_device.enable() return new_device def destroy_device(self, device): + """Destroys a DiskDevice instance previously created by + get_device method. + """ self._devices.remove(device) device.destroy() + class DiskDevice(object): + """This class represents a block device hosting an Operating System + as created by the device-mapper. + """ + + def __init__(self, device, bootable=True): + """Create a new DiskDevice.""" - def __init__(self, device, bootable = True): self.device = device self.bootable = bootable + self.progress_bar = None self.g = guestfs.GuestFS() + self.g.add_drive_opts(self.device, readonly=0) + + #self.g.set_trace(1) + #self.g.set_verbose(1) - self.g.set_trace(1) + self.guestfs_enabled = False - self.g.add_drive_opts(device, readonly = 0) + def enable(self): + """Enable a newly created DiskDevice""" + self.progressbar = progress("Launching helper VM: ") + self.progressbar.next() + eh = self.g.set_event_callback(self.progress_callback, + guestfs.EVENT_PROGRESS) self.g.launch() + self.guestfs_enabled = True + self.g.delete_event_callback(eh) + if self.progressbar is not None: + self.progressbar.send(100) + self.progressbar = None + + output('Inspecting Operating System...', False) roots = self.g.inspect_os() if len(roots) == 0: - raise DiskError("No operating system found") + raise FatalError("No operating system found") if len(roots) > 1: - raise DiskError("Multiple operating systems found") - + raise FatalError("Multiple operating systems found." + "We only support images with one filesystem.") self.root = roots[0] self.ostype = self.g.inspect_get_type(self.root) self.distro = self.g.inspect_get_distro(self.root) - + success('found a %s system' % self.distro) + def destroy(self): - self.g.umount_all() - self.g.sync() - # Close the guestfs handler + """Destroy this DiskDevice instance.""" + + if self.guestfs_enabled: + self.g.umount_all() + self.g.sync() + + # Close the guestfs handler if open self.g.close() - del self.g - + + def progress_callback(self, ev, eh, buf, array): + position = array[2] + total = array[3] + + self.progressbar.send((position * 100) // total) + + if position == total: + self.progressbar = None + def mount(self): + """Mount all disk partitions in a correct order.""" + + output("Mounting image...", False) mps = self.g.inspect_get_mountpoints(self.root) + # Sort the keys to mount the fs in a correct order. # / should be mounted befor /boot, etc - def compare (a, b): - if len(a[0]) > len(b[0]): return 1 - elif len(a[0]) == len(b[0]): return 0 - else: return -1 + def compare(a, b): + if len(a[0]) > len(b[0]): + return 1 + elif len(a[0]) == len(b[0]): + return 0 + else: + return -1 mps.sort(compare) for mp, dev in mps: try: self.g.mount(dev, mp) except RuntimeError as msg: - print "%s (ignored)" % msg + warn("%s (ignored)" % msg) + success("done") + + def umount(self): + """Umount all mounted filesystems.""" + self.g.umount_all() + + def shrink(self): + """Shrink the disk. + + This is accomplished by shrinking the last filesystem in the + disk and then updating the partition table. The new disk size + (in bytes) is returned. + """ + output("Shrinking image (this may take a while)...", False) + + dev = self.g.part_to_dev(self.root) + parttype = self.g.part_get_parttype(dev) + if parttype != 'msdos': + raise FatalError("You have a %s partition table. " + "Only msdos partitions are supported" % parttype) + + last_partition = self.g.part_list(dev)[-1] + + if last_partition['part_num'] > 4: + raise FatalError("This disk contains logical partitions. " + "Only primary partitions are supported.") + + part_dev = "%s%d" % (dev, last_partition['part_num']) + fs_type = self.g.vfs_type(part_dev) + if not re.match("ext[234]", fs_type): + warn("Don't know how to resize %s partitions." % vfs_type) + return + + self.g.e2fsck_f(part_dev) + self.g.resize2fs_M(part_dev) + + output = self.g.tune2fs_l(part_dev) + block_size = int( + filter(lambda x: x[0] == 'Block size', output)[0][1]) + block_cnt = int( + filter(lambda x: x[0] == 'Block count', output)[0][1]) + + sector_size = self.g.blockdev_getss(dev) + + start = last_partition['part_start'] / sector_size + end = start + (block_size * block_cnt) / sector_size - 1 + + self.g.part_del(dev, last_partition['part_num']) + self.g.part_add(dev, 'p', start, end) + + new_size = (end + 1) * sector_size + success("new image size is %dMB" % + ((new_size + 2 ** 20 - 1) // 2 ** 20)) + return new_size + + def size(self): + """Returns the "payload" size of the device. + + The size returned by this method is the size of the space occupied by + the partitions (including the space before the first partition). + """ + dev = self.g.part_to_dev(self.root) + last = self.g.part_list(dev)[-1] + + return last['part_end'] + 1 + + def dump(self, outfile): + """Dumps the content of device into a file. + + This method will only dump the actual payload, found by reading the + partition table. Empty space in the end of the device will be ignored. + """ + blocksize = 2 ** 22 # 4MB + size = self.size() + progress_size = (size + 2 ** 20 - 1) // 2 ** 20 # in MB + progressbar = progress("Dumping image file: ", progress_size) + + source = open(self.device, "r") + try: + dest = open(outfile, "w") + try: + left = size + offset = 0 + progressbar.next() + while left > 0: + length = min(left, blocksize) + sent = sendfile(dest.fileno(), source.fileno(), offset, + length) + offset += sent + left -= sent + for i in range((length + 2 ** 20 - 1) // 2 ** 20): + progressbar.next() + finally: + dest.close() + finally: + source.close() + + success('Image file %s was successfully created' % outfile) # vim: set sta sts=4 shiftwidth=4 sw=4 et ai :