X-Git-Url: https://code.grnet.gr/git/snf-image-creator/blobdiff_plain/6f319b6a89c476269783e4b89a60e393bf56f38a..29fd973e0da4b1bf61f76a7809b67b18ef9db195:/image_creator/disk.py diff --git a/image_creator/disk.py b/image_creator/disk.py index 01ff41d..b4311f8 100644 --- a/image_creator/disk.py +++ b/image_creator/disk.py @@ -32,21 +32,17 @@ # or implied, of GRNET S.A. from image_creator.util import get_command -from image_creator.util import warn, progress, success, output, FatalError +from image_creator.util import try_fail_repeat +from image_creator.util import free_space +from image_creator.util import FatalError +from image_creator.bundle_volume import BundleVolume +from image_creator.image import Image import stat import os import tempfile import uuid -import re -import sys -import guestfs -import time -from sendfile import sendfile - - -class DiskError(Exception): - pass +import shutil dd = get_command('dd') dmsetup = get_command('dmsetup') @@ -54,6 +50,9 @@ losetup = get_command('losetup') blockdev = get_command('blockdev') +TMP_CANDIDATES = ['/var/tmp', os.path.expanduser('~'), '/mnt'] + + class Disk(object): """This class represents a hard disk hosting an Operating System @@ -62,280 +61,137 @@ class Disk(object): the Linux kernel. """ - def __init__(self, source): + def __init__(self, source, output, tmp=None): """Create a new Disk instance out of a source media. The source - media can be an image file, a block device or a directory.""" + media can be an image file, a block device or a directory. + """ self._cleanup_jobs = [] - self._devices = [] + self._images = [] self.source = source + self.out = output + self.meta = {} + self.tmp = tempfile.mkdtemp(prefix='.snf_image_creator.', + dir=self._get_tmp_dir(tmp)) + + self._add_cleanup(shutil.rmtree, self.tmp) + + def _get_tmp_dir(self, default=None): + """Check tmp directory candidates and return the one with the most + available space. + """ + if default is not None: + return default + + space = map(free_space, TMP_CANDIDATES) + + max_idx = 0 + max_val = space[0] + for i, val in zip(range(len(space)), space): + if val > max_val: + max_val = val + max_idx = i + + # Return the candidate path with more available space + return TMP_CANDIDATES[max_idx] def _add_cleanup(self, job, *args): + """Add a new job in the cleanup list""" self._cleanup_jobs.append((job, args)) def _losetup(self, fname): + """Setup a loop device and add it to the cleanup list. The loop device + will be detached when cleanup is called. + """ loop = losetup('-f', '--show', fname) loop = loop.strip() # remove the new-line char - self._add_cleanup(losetup, '-d', loop) + self._add_cleanup(try_fail_repeat, losetup, '-d', loop) return loop def _dir_to_disk(self): - raise NotImplementedError + """Create a disk out of a directory""" + if self.source == '/': + bundle = BundleVolume(self.out, self.meta) + image = '%s/%s.diskdump' % (self.tmp, uuid.uuid4().hex) + + def check_unlink(path): + if os.path.exists(path): + os.unlink(path) + + self._add_cleanup(check_unlink, image) + bundle.create_image(image) + return self._losetup(image) + raise FatalError("Using a directory as media source is supported") 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. + try: + while len(self._images): + image = self._images.pop() + image.destroy() + finally: + # Make sure those are executed even if one of the device.destroy + # methods throws exeptions. + while len(self._cleanup_jobs): + job, args = self._cleanup_jobs.pop() + job(*args) + + def snapshot(self): + """Creates a snapshot of the original source media of the Disk + instance. """ - output("Examining source media `%s'..." % self.source, False) + self.out.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()) + self.out.success('looks like a directory') + return self._dir_to_disk() elif stat.S_ISREG(mode): - success('looks like an image file') + self.out.success('looks like an image file') sourcedev = self._losetup(self.source) elif not stat.S_ISBLK(mode): - raise ValueError("Invalid media source. Only block devices, " - "regular files and directories are supported.") + raise FatalError("Invalid media source. Only block devices, " + "regular files and directories are supported.") else: - success('looks like a block device') + self.out.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() + self.out.output("Snapshotting media source...", False) + size = blockdev('--getsz', sourcedev) + cowfd, cow = tempfile.mkstemp(dir=self.tmp) os.close(cowfd) self._add_cleanup(os.unlink, cow) - # Create 1G cow sparse file - dd('if=/dev/null', 'of=%s' % cow, 'bs=1k', \ - 'seek=%d' % (1024 * 1024)) + # Create cow sparse file + dd('if=/dev/null', 'of=%s' % cow, 'bs=512', 'seek=%d' % int(size)) cowdev = self._losetup(cow) snapshot = uuid.uuid4().hex tablefd, table = tempfile.mkstemp() try: - os.write(tablefd, "0 %d snapshot %s %s n 8" % \ - (int(size), sourcedev, cowdev)) + os.write(tablefd, "0 %d snapshot %s %s n 8" % + (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) + self._add_cleanup(try_fail_repeat, dmsetup, 'remove', snapshot) 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.""" - - 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.guestfs_enabled = False - - 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 FatalError("No operating system found") - if len(roots) > 1: - 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) + self.out.success('done') + return "/dev/mapper/%s" % snapshot - def destroy(self): - """Destroy this DiskDevice instance.""" + def get_image(self, media): + """Returns a newly created Image instance.""" - if self.guestfs_enabled: - self.g.umount_all() - self.g.sync() + image = Image(media, self.out) + self._images.append(image) + image.enable() + return image - # Close the guestfs handler if open - self.g.close() - - 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 - mps.sort(compare) - for mp, dev in mps: - try: - self.g.mount(dev, mp) - except RuntimeError as 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) - - out = self.g.tune2fs_l(part_dev) - block_size = int( - filter(lambda x: x[0] == 'Block size', out)[0][1]) - block_cnt = int( - filter(lambda x: x[0] == 'Block count', out)[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). + def destroy_image(self, image): + """Destroys an Image instance previously created by get_image method. """ - 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) + self._images.remove(image) + image.destroy() # vim: set sta sts=4 shiftwidth=4 sw=4 et ai :