from pbs import blockdev
from pbs import dd
-class DiskError(Exception): pass
+
+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
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.
+ """
sourcedev = self.source
mode = os.stat(self.source).st_mode
if stat.S_ISDIR(mode):
size = blockdev('--getsize', sourcedev)
cowfd, cow = tempfile.mkstemp()
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
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):
+ def __init__(self, device, bootable=True):
+ """Create a new DiskDevice."""
self.device = device
self.bootable = bootable
self.g.set_trace(1)
- self.g.add_drive_opts(device, readonly = 0)
+ self.g.add_drive_opts(device, readonly=0)
self.g.launch()
roots = self.g.inspect_os()
if len(roots) == 0:
self.root = roots[0]
self.ostype = self.g.inspect_get_type(self.root)
self.distro = self.g.inspect_get_distro(self.root)
-
+
def destroy(self):
+ """Destroy this DiskDevice instance."""
self.g.umount_all()
self.g.sync()
# Close the guestfs handler
self.g.close()
- del self.g
-
+
def mount(self):
+ """Mount all disk partitions in a correct order."""
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:
except RuntimeError as msg:
print "%s (ignored)" % msg
+ 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.
+ """
+ dev = self.g.part_to_dev(self.root)
+ parttype = self.g.part_get_parttype(dev)
+ if parttype != 'msdos':
+ raise DiskError("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 DiskError("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):
+ print "Warning: 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)
+
+ return (end + 1) * sector_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']
+
# vim: set sta sts=4 shiftwidth=4 sw=4 et ai :
projects / snf-image-creator / blobdiff