import tempfile
import uuid
import re
+import sys
+import guestfs
+
from pbs import dmsetup
from pbs import blockdev
from pbs import dd
-from pbs import kpartx
-from pbs import mount
-from pbs import umount
+
+
+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)
- dd('if=/dev/zero', 'of=%s' % cow, 'count=%d' % (1024*1024))#(int(size)/4))
+ # 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
finally:
os.unlink(table)
- new_device = DiskDevice(self, "/dev/mapper/%s" % snapshot)
+ new_device = DiskDevice("/dev/mapper/%s" % snapshot)
self._devices.append(new_device)
return new_device
-class DiskDevice(object):
-
- def __init__(self, disk, device):
- self.disk = disk
- self.dev = device
- self.partitions_mapped = False
- self.magic_number = uuid.uuid4().hex
-
- def list_partitions(self):
- output = kpartx("-l", "-p", self.magic_number, self.dev)
- return [ "/dev/mapper/%s" % x for x in
- re.findall('^\S+', str(output), flags=re.MULTILINE)]
-
- def mount(self, partition):
- if not self.partitions_mapped:
- kpartx("-a", "-p", self.magic_number, self.dev)
- self.disk._cleanup_jobs.append(kpartx, "-d", "-p",
- self.magic_number, self.dev)
- self.partitions_mapped = True
-
- targetfd, target = tempfile.mkdtemp()
- try:
- mount(dev, partition)
- except:
- os.rmdir(table)
- raise
- return target
+ def destroy_device(self, device):
+ """Destroys a DiskDevice instance previously created by
+ get_device method.
+ """
+ self._devices.remove(device)
+ device.destroy()
- def unmount(self, partition):
- umount(target)
- mode = os.stat(self.source).st_mode
- if stat.S_ISDIR(mode):
- os.rmdir(target)
+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.g = guestfs.GuestFS()
+
+ self.g.set_trace(1)
+
+ self.g.add_drive_opts(device, readonly=0)
+ self.g.launch()
+ roots = self.g.inspect_os()
+ if len(roots) == 0:
+ raise DiskError("No operating system found")
+ if len(roots) > 1:
+ raise DiskError("Multiple operating systems found")
+
+ 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()
+
+ 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
+ mps.sort(compare)
+ for mp, dev in mps:
+ try:
+ self.g.mount(dev, mp)
+ 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