disktools.py

# SPDX-License-Identifier: GPL-2.0-only

import constants
import errno
import re, subprocess, types, os, time
from pprint import pprint
from copy import copy, deepcopy
import util
from xcp import logger

class Segment:
    """Segments are areas, e.g. disk partitions or LVM segments, defined by start address and size"""
    def __init__(self, start, size):
        self.start = start
        self.size = size

    def end(self):
        return self.start + self.size

    def __repr__(self):
        repr = { 'end' : self.end() }
        repr.update(self.__dict__)
        return str(repr)

class MoveChunk:
    """MoveChunks represent a move.  They contain source and destination addresses"""
    def __init__(self, src, dest, size):
        self.src = src
        self.dest = dest
        self.size = size

    def __repr__(self):
        return str(self.__dict__)

class FreePool:
    """FreePool manages the allotment of segments a pool of free segments, and
    divides segments as necessary to fill the requested size exactly"""
    def __init__(self, freeSegments, usedThreshold=0):
        self.freeSegments = freeSegments
        # Instead of altering the free segment list as free space is consumed by takeSegments,
        # this class maintains a usedThreshold address.  Addresses lower than the threshold
        # have already been used, and those at or above it are still available
        self.usedThreshold = usedThreshold

    def freeSpace(self):
        sizeLeft = 0
        for seg in self.freeSegments:
            freeSize = min(seg.size, seg.end() - self.usedThreshold)
            if freeSize > 0:
                sizeLeft += freeSize

        return sizeLeft

    def takeSegments(self, size):
        """Returns a LIST of segments that fill the requested size, and effectively removes
        those segments from the free pool by increasing usedThreshold"""
        initialFreeSpace = self.freeSpace()
        segsToTake = []
        sizeLeft = size
        for seg in self.freeSegments:
            availableStart = max(seg.start, self.usedThreshold)
            sizeToTake = min(seg.end() - availableStart, sizeLeft)
            if sizeToTake > 0:
                takenSegment = Segment(availableStart, sizeToTake)
                segsToTake.append(takenSegment)
                self.usedThreshold = takenSegment.end()
                sizeLeft -= takenSegment.size
            assert sizeLeft >= 0 # Underflow implies a logic error

        if sizeLeft > 0:
            raise Exception("Disk allocation failed - out of space")

        assert size == sum([seg.size for seg in segsToTake]) # Check we've allocated the size required
        assert size == initialFreeSpace - self.freeSpace() # Check that free space has shrunk by the right amount

        return segsToTake

    def __repr__(self):
        return str(self.__dict__)

class LVMTool:
    # Separation character - mustn't appear in anything we expect back from pvs/vgs/lvs
    SEP = '#'

    # Evacuate this many more extents than pvresize theoretically requires
    PVRESIZE_EXTENT_MARGIN = 0

    # Volume group prefixes
    VG_SWAP_PREFIX = 'VG_XenSwap'
    VG_CONFIG_PREFIX = 'VG_XenConfig'
    # Prefix used by the SR type 'lvm'
    VG_SR_PREFIX = 'VG_XenStorage'
    # Prefix for non-'lvm' local storage SR types
    VG_OTHER_SR_PREFIX = 'XSLocal'

    PVMOVE = ['pvmove']
    LVCHANGE = ['lvchange']
    LVREMOVE = ['lvremove']
    VGCHANGE = ['vgchange']
    VGREMOVE = ['vgremove']
    PVREMOVE = ['pvremove']
    PVRESIZE = ['pvresize']

    VGS_INFO = { # For one-per-VG records
        'command' : ['/sbin/lvm', 'vgs'],
        'arguments' : ['--noheadings', '--nosuffix', '--units', 'b', '--separator', SEP],
        'string_options' : ['vg_name'],
        'integer_options' : []
    }

    LVS_SEG_INFO = { # For one-per-LV-segment records
        'command' : ['/sbin/lvm', 'lvs'],
        'arguments' : ['--noheadings', '--nosuffix', '--units', 'b', '--separator', SEP, '--segments'],
        'string_options' : ['seg_pe_ranges'],
        'integer_options' : []
    }
    LVS_INFO = { # For one-per-LV records
        'command' : ['/sbin/lvm', 'lvs'],
        'arguments' : ['--noheadings', '--nosuffix', '--units', 'b', '--separator', SEP],
        'string_options' : ['lv_name', 'vg_name'],
        'integer_options' : []
    }
    PVS_INFO = { # For one-per-PV records
        'command' : ['/sbin/lvm', 'pvs'],
        'arguments' : ['--noheadings', '--nosuffix', '--units', 'b', '--separator', SEP],
        'string_options' : ['pv_name', 'vg_name'],
        'integer_options' : ['pe_start', 'pv_size', 'pv_free', 'pv_pe_count', 'dev_size']
    }

    def __init__(self):
        self.readAllInfo()
        self.pvsToDelete = []
        self.vgsToDelete = []
        self.lvsToDelete = []
        # moveLists are per device, so self.moveLists might be{ '/dev/sda3': [MoveChunk, MoveChunk, ...], '/dev/sdb3' : ... }
        self.moveLists = {}
        self.resizeList = []

    @classmethod
    def cmdWrap(cls, params):
        rv, out, err = util.runCmd2(params, True, True)
        if rv != 0:
            if isinstance(err, (types.ListType, types.TupleType)):
                raise Exception("\n".join(err)+"\nError="+str(rv))
            else:
                raise Exception(str(err)+"\nError="+str(rv))
        return out

    def readInfo(self, info):
        retVal = []
        allOptions = info['string_options'] + info['integer_options']
        cmd = info['command'] + info['arguments'] + ['--options', ','.join(allOptions)]
        out = self.cmdWrap(cmd)

        for line in out.strip().split('\n'):
            # skip blank lines
            if line == '':
                continue
            try:
                # Create a dict of the form 'option_name':value
                data = dict(zip(allOptions, line.lstrip().split(self.SEP)))
                if len(data) != len(allOptions):
                    raise Exception("Wrong number of options in reply")
                for name in info['integer_options']:
                    # Convert integer options to integer type
                    data[name] = int(data[name])
                retVal.append(data)
            except Exception as e:
                logger.log("Discarding corrupt LVM output line '"+str(line)+"'")
                logger.log("  Command was '"+str(cmd)+"'")
                logger.log("  Error was '"+str(e)+"'")

        return retVal

    def readAllInfo(self):
        self.vgs = self.readInfo(self.VGS_INFO)
        self.lvs = self.readInfo(self.LVS_INFO)
        self.lvSegs = self.readInfo(self.LVS_SEG_INFO)
        self.pvs = self.readInfo(self.PVS_INFO)
        # For DM nodes "pvs" incorrectly returns /dev/dm-n, which does not exist.
        # Replace occurrences of /dev/dm-n with the correct node under /dev/mapper/
        for pv in self.pvs:
            name = pv['pv_name']
            if name.startswith('/dev/dm-'):
                n = int(name[8:])
                pv['pv_name'] = getDeviceMapperNode(n)

    @classmethod
    def decodeSegmentRange(cls, segRange):
        # Handle only a single range, e.g. '/dev/sdb3:11001-16158'
        matches = re.match(r'([^:]+):([0-9]+)-([0-9]+)$', segRange)
        if not matches:
            raise Exception("Could not decode segment range from '"+segRange+"'")
        # End value is inclusive, so 0-0 is one segment long
        return {
            'device' : matches.group(1),
            'start' : int(matches.group(2)),
            'size' : int(matches.group(3)) - int(matches.group(2)) + 1 # +1 because end is inclusive
        }

    @classmethod
    def encodeSegmentRange(cls, device, start, size):
        endInclusive = start+size-1
        if start < 0 or endInclusive < start:
            raise Exception("Invalid segment to encode: "+str(device)+', start='+str(start)+', size='+str(size))
        retVal = device+':'+str(start)+'-'+str(endInclusive)
        return retVal

    def segmentList(self, device):
        # PV segments don't record whether the segment is free space or not, so iterate through
        # the LV segments for the device instead
        segments = []
        for lvSeg in self.lvSegs:
            segRange = self.decodeSegmentRange(lvSeg['seg_pe_ranges'])
            if segRange['device'] == device:
                segments.append(Segment(segRange['start'], segRange['size']))
        segments.sort(lambda x, y : cmp(x.start, y.start))
        return segments

    def freeSegmentList(self, device):
        pv = self.deviceToPV(device)
        usedSegs = self.segmentList(device)
        # Add a fake zero-sized end segment to the list, so the unallocated space at the end
        # of the volume is a gap between two segments and not a special case
        fakeEndSeg = Segment(pv['pv_pe_count'], 0)
        usedSegs.append(fakeEndSeg)
        freeSegs = []
        # Iterate over pairs of consecutive segments
        for seg, nextSeg in zip(usedSegs[:-1], usedSegs[1:]):
            # ... work out the gap between them ...
            gapSize = nextSeg.start - seg.end()
            if gapSize > 0:
                # ... and add that to the free segment list
                freeSegs.append(Segment(seg.end(), gapSize))

        return freeSegs

    def segmentsToMove(self, device, threshold):
        """Given a device, i.e. a partition containing an LVM volume, and a threshold in extents,
        returns the segments that would need to be moved so that all non-free segments are
        below that address.  Can add just part of a segment if the original straddles the threshold"""
        segsToMove = []
        for seg in self.segmentList(device):
            if seg.end() > threshold:
                start = max(seg.start, threshold)
                segsToMove.append(Segment(start, seg.end() - start))
        return segsToMove

    def makeSpaceAfterThreshold(self, device, thresholdExtent):
        """Queues up a set of MoveChunks that will free up space at the end of a PV so that
        a pvresize cammand can succeed, and these will lead to pvmove commands at
        commit time.  Doesn't queue up the pvresize command itself - resizeDevice will do that..
        Also safe to call if no pvmoves are necessary"""
        pv = self.deviceToPV(device)
        # Extents >= thresholdExtent must be freed.
        segsToMove = self.segmentsToMove(device, thresholdExtent)

        # Calculate the free pool if we haven't already.  If we have done it already, we've been
        # here before for this device, so use the existing FreePool object as it knows how much
        # free space is already used by reallocation
        if 'free-pool' not in pv:
            pv['free-pool'] =  FreePool(self.freeSegmentList(device))

        # Take a copy.  We'll only commit our modified copy back to pv['free-pool']  if our transaction succeeds
        freePool = deepcopy(pv['free-pool'])
        moveList = []

        for srcSeg in segsToMove:
            srcOffset = 0
            destSegs = freePool.takeSegments(srcSeg.size)
            # destSegs are a tailor-made set of segments to consume srcSeg exactly, and the loop
            # beow relies on that
            for destSeg in destSegs:
                # Divide up the source segments into the destination segments
                srcStart = srcSeg.start + srcOffset
                destStart = destSeg.start
                moveList.append(MoveChunk(srcStart, destStart, destSeg.size))
                srcOffset += destSeg.size
            assert srcOffset == srcSeg.size # Logic error if not

        # Add our moves to the current MoveChunk list for this device, creating the
        # dict element if necessary
        self.moveLists[device] = self.moveLists.get(device, []) + moveList
        pv['free-pool'] = freePool

    def deviceToPVOrNone(self, device):
        """ Returns the PV record for a given device (partition), or None if there is no PV
        for that device."""
        for pv in self.pvs:
            if pv['pv_name'] == device:
                return pv
        return None

    def deviceToPV(self, device):
        pv = self.deviceToPVOrNone(device)
        if pv is None:
            raise Exception("PV for device '"+str(device)+"' not found")
        return pv

    def vGContainingLV(self, lvol):
        for lv in self.lvs:
            if lv['lv_name'] == lvol:
                return lv['vg_name']
        raise Exception("VG for LV '"+lvol+"' not found")

    def deviceSize(self, device):
        pv = self.deviceToPV(device)
        return pv['pv_size'] # in bytes

    def deviceFreeSpace(self, device):
        pv = self.deviceToPV(device)
        return pv['pv_free'] # in bytes

    def resizeDevice(self, device, byteSize):
        """ Resizes the PV on a device, moving extents around if necessary
        """
        pv = self.deviceToPV(device)
        if byteSize > pv['dev_size']:
            raise Exception("Size requested for "+str(device)+" ("+str(byteSize)+
                ") is greater than device size ("+str(pv['dev_size'])+")")

        extentBytes = pv['pv_size'] // pv['pv_pe_count'] # Typically 4MiB
        # Calculate the threshold in extents beyond which segments must be moved elsewhere.
        # Round down, so enough space is freed for pvresize to complete, and allow
        # PVRESIZE_EXTENT_MARGIN for extents consumed by LVM metadata
        metadataExtents = (pv['pe_start'] + extentBytes - 1) // extentBytes # Round up

        thresholdExtent = byteSize // extentBytes - metadataExtents - self.PVRESIZE_EXTENT_MARGIN
        self.makeSpaceAfterThreshold(device, thresholdExtent)
        self.resizeList.append({'device' : device, 'bytesize' : byteSize})

    def testPartition(self, devicePrefix, vgPrefix):
        """Returns the first partition where the device name starts with devicePrefix and
        the volume group that it's in starts with vgPrefix"""
        retVal = None
        for pv in self.pvs:
            if pv['pv_name'].startswith(devicePrefix) and pv['vg_name'].startswith(vgPrefix):
                retVal = pv['pv_name']
                break
        return retVal

    def configPartition(self, devicePrefix):
        """Returns the PV name for a config partition on the specified WHOLE DEVICE, e.g. '/dev/sda',
        or None if none present"""
        return self.testPartition(devicePrefix, self.VG_CONFIG_PREFIX)

    def swapPartition(self, devicePrefix):
        return self.testPartition(devicePrefix, self.VG_SWAP_PREFIX)

    def srPartition(self, devicePrefix):
        retVal = self.testPartition(devicePrefix, self.VG_SR_PREFIX)
        if retVal is None:
            retVal = self.testPartition(devicePrefix, self.VG_OTHER_SR_PREFIX)
        return retVal

    def isPartitionConfig(self, device):
        """Returns True if there is a config partition on the specified PARTITION, e.g. '/dev/sda2',
        or False if none present"""
        pv = self.deviceToPVOrNone(device)
        return pv is not None and pv['vg_name'].startswith(self.VG_CONFIG_PREFIX)

    def isPartitionSwap(self, device):
        pv = self.deviceToPVOrNone(device)
        return pv is not None and pv['vg_name'].startswith(self.VG_SWAP_PREFIX)

    def isPartitionSR(self, device):
        pv = self.deviceToPVOrNone(device)
        return pv is not None and (pv['vg_name'].startswith(self.VG_SR_PREFIX) or \
                                   pv['vg_name'].startswith(self.VG_OTHER_SR_PREFIX))

    def deleteDevice(self, device):
        """Deletes PVs, VGs and LVs associated with a device (partition)"""
        pvsToDelete = []
        vgsToDelete = []
        lvsToDelete = []

        for pv in self.pvs:
            if pv['pv_name'] == device:
                pvsToDelete.append(pv['pv_name'])
                vgsToDelete.append(pv['vg_name'])

        for lv in self.lvs:
            if lv['vg_name'] in vgsToDelete:
                # lvremove requires a 'path': <VG name>/<LV name>
                lvsToDelete.append(lv['vg_name']+'/'+lv['lv_name'])

        self.pvsToDelete += pvsToDelete
        self.vgsToDelete += vgsToDelete
        self.lvsToDelete += lvsToDelete

    def activateVG(self, vg):
        self.cmdWrap(self.VGCHANGE + ['-ay', vg])

    def deactivateVG(self, vg):
        self.cmdWrap(self.VGCHANGE + ['-an', vg])

    def deactivateAll(self):
        """Makes sure that LVM has unmounted everything so that, e.g. sfdisk can succeed"""
        for vg in self.vgs:
            # Passing VG names to LVchange is intentional
            try:
                self.cmdWrap(self.LVCHANGE + ['-an', vg['vg_name']])
            except Exception as e:
                logger.logException(e)

    @classmethod
    def executeMoves(cls, progress_callback, device, moveList):
        # Call commit instead this method unless you have special requirements
        """Issues pvmove commands to move MoveChunks specified by the MoveList.  Doesn't
        handle overlapping source and destination segments in a single MoveChunk, but in
        a makeSpaceAtEnd scenario those aren't generated"""
        sizeStep = 16 # Moving 16 extents takes only slightly more time than moving 1
        totalExtents = sum(move.size for move in moveList)
        extentsSoFar = 0
        for move in moveList:
            offset = 0
            while offset < move.size:
                progress_callback((100 * extentsSoFar) / totalExtents)
                chunkSize = min(sizeStep, move.size - offset)
                srcRange = cls.encodeSegmentRange(device, move.src + offset, chunkSize)
                destRange = cls.encodeSegmentRange(device, move.dest + offset, chunkSize)
                cls.cmdWrap(cls.PVMOVE +
                    [
                    '--alloc',
                    'anywhere',
                    srcRange,
                    destRange
                ])
                offset += chunkSize
                extentsSoFar += chunkSize

    def commit(self, progress_callback=lambda _ : ()):
        """Commit the changes queued up by issuing LVM commands, delete our queues as they
        succeed, and then reread the new configuration from LVM"""
        progress_callback(0)
        # Abort pvmoves if any have been left partiially completed by e.g. a crash
        self.cmdWrap(self.PVMOVE + ['--abort'])
        self.deactivateAll()
        progress_callback(1)

        # Process delete lists
        for lv in self.lvsToDelete:
            self.cmdWrap(self.LVREMOVE + [lv])
        self.lvsToDelete = []
        progress_callback(2)
        for vg in self.vgsToDelete:
            self.cmdWrap(self.VGREMOVE + [vg])
        self.vgsToDelete = []
        progress_callback(3)
        for pv in self.pvsToDelete:
            self.cmdWrap(self.PVREMOVE + ['--force', '--yes', pv])
        self.pvsToDelete = []
        progress_callback(4)

        # Process move lists.  Most of the code here is for calculating smoothly
        # increasing progress values
        totalExtents = 0
        for moveList in self.moveLists.values():
            totalExtents += sum([ move.size for move in moveList ])
        extentsSoFar = 0

        for device, moveList in sorted(self.moveLists.items()):
            thisSize = sum([ move.size for move in moveList ])
            callback = lambda percent : (progress_callback( 5 + (98 - 5) * (extentsSoFar + thisSize * percent / 100) / totalExtents) )
            self.executeMoves(callback, device, moveList)
            extentsSoFar +=  thisSize
        self.moveLists = {}

        # Process resize list
        progress_callback(98)
        for resize in self.resizeList:
            self.cmdWrap(self.PVRESIZE + ['--setphysicalvolumesize', str(resize['bytesize']//1024)+'k', resize['device']])
        self.resizeList = []

        self.readAllInfo() # Reread the new LVM configuration
        progress_callback(99)
        self.deactivateAll() # Stop active LVs preventing changes to the partition structure
        progress_callback(100)

    def dump(self):
        pprint(self.__dict__)

def diskDevice(partitionDevice):
    matches = re.match(r'(.+)(p?|(-part))\d+$', partitionDevice)
    if matches:
        return matches.group(1)
    matches = re.match(r'(.+\D)\d+$', partitionDevice)
    if not matches:
        raise Exception("Could not determine disk device for device '"+partitionDevice+"'")
    return matches.group(1)

def determineMidfix(device):
    DISK_PREFIX = '/dev/'
    P_STYLE_DISKS = [ 'cciss', 'ida', 'rd', 'sg', 'i2o', 'amiraid', 'iseries', 'emd', 'carmel', 'mapper/', 'nvme', 'md', 'mmcblk' ]
    PART_STYLE_DISKS = [ 'disk/by-id' ]

    for key in P_STYLE_DISKS:
        if device.startswith(DISK_PREFIX + key):
            return '' if re.match(r'.+\D$', device) else 'p'
    for key in PART_STYLE_DISKS:
        if device.startswith(DISK_PREFIX + key):
            return '-part'
    return ''

def partitionDevice(device, deviceNum):
    return device + determineMidfix(device) + str(deviceNum)


def roundUp(n, mult):
    n += mult - 1
    return n - n % mult

class PartitionToolBase:
    """
    Base class for the DOS and GPT Partition Tool classes.
    Contains common code.
    """
    BLOCKDEV = '/sbin/blockdev'

    DEFAULT_SECTOR_SIZE = 512 # Used if sfdisk won't print its (hardcoded) value

    def __init__(self, device):
        self.sectorAlignment = 1
        self.device = device
        self.midfix = determineMidfix(device)
        self.readDiskDetails()
        self.partitions = self.partitionTable()
        self.origPartitions = deepcopy(self.partitions)

    def partitionNumber(self, partitionDevice):
        matches = re.match(self.device + self.midfix + r'(\d+)$', partitionDevice)
        if not matches:
            raise Exception("Could not determine partition number for device '"+partitionDevice+"'")
        return int(matches.group(1))

    # Private methods:
    def cmdWrap(self, params):
        rv, out, err = util.runCmd2(params, True, True)
        if rv != 0:
            raise Exception(err)
        return out

    def _partitionDevice(self, deviceNum):
        return self.device + self.midfix + str(deviceNum)

    def _partitionNumber(self, partitionDevice):
        # sfdisk is inconsistent in naming partitions of by-id devices
        matches = re.match(self.device + r'\D*(\d+)$', partitionDevice)
        if not matches:
            raise Exception("Could not determine partition number for device '"+partitionDevice+"'")
        return int(matches.group(1))

    def settleUdev(self):
        timeout = 30
        try:
            self.cmdWrap(util.udevsettleCmd() + ['--timeout=%d' % timeout ])
        except:
            logger.log('udevsettle with %d second timeout failed' % timeout)

    def waitForDeviceNodes(self):
        # Ensure new device nodes are available before we continue.
        # Wait a second to ensure that udev picks up the change event from
        # the kernel, then call settle to wait for all events complete.
        time.sleep(1)
        self.settleUdev()

    def writePartitionTable(self, dryrun=False, log=False):
        try:
            self.writeThisPartitionTable(self.partitions, dryrun, log)
        except Exception as e:
            try:
                # Revert to the original partition table
                self.writeThisPartitionTable(self.origPartitions, dryrun)
            except Exception as e2:
                raise Exception('The new partition table could not be written: '+str(e)+'\nReversion also failed: '+str(e2))
            raise Exception('The new partition table could not be written but was reverted successfully: '+str(e))
        else:
            self.waitForDeviceNodes()

    # Public methods from here onward:
    def getPartition(self, number, default=None):
        return deepcopy(self.partitions.get(number, default))

    def createPartition(self, id, sizeBytes=None, number=None, order=None, startBytes=None, active=False):
        if number is None:
            if len(self.partitions) == 0:
                newNumber = 1
            else:
                newNumber = 1+max(self.partitions.keys())
        else:
            newNumber = number
        if newNumber in self.partitions:
            raise Exception('Partition '+str(newNumber)+' already exists')

        partitions = [None] + [part for num, part in sorted(self.partitions.items(), key=lambda item: item[1]['start'])]

        if startBytes is None:
            if order:
                if order < 1:
                    raise Exception("Order cannot be less than 1")
                elif order == 1:
                    startSector = self.sectorFirstUsable
                else:
                    startSector =  partitions[order - 1]['start'] + partitions[order - 1]['size']
            else:
                startSector =  partitions[-1]['start'] + partitions[-1]['size']
            startSector = roundUp(startSector, self.sectorAlignment)
        else:
            if startBytes % self.sectorSize != 0:
                raise Exception("Partition start ("+str(startBytes)+") is not a multiple of the sector size "+str(self.sectorSize))
            startSector = startBytes // self.sectorSize

        if sizeBytes is None:
            if order:
                if order < 1:
                    raise Exception("Order cannot be less than 1")
                elif order > len(partitions):
                    raise Exception("Order too large")
                elif order == len(partitions):
                    sizeSectors = self.sectorLastUsable + 1 - startSector
                else:
                    sizeSectors =  partitions[order]['start'] - startSector
            else:
                sizeSectors = self.sectorLastUsable + 1 - startSector
        else:
            if sizeBytes % self.sectorSize != 0:
                raise Exception("Partition size ("+str(sizeBytes)+") is not a multiple of the sector size "+str(self.sectorSize))

            sizeSectors = sizeBytes // self.sectorSize

        if sizeSectors < 0:
            self.dump()
            raise Exception("Partition size in sectors ("+str(sizeSectors)+") is negative")

        self.partitions[newNumber] = {
            'start': startSector,
            'size': sizeSectors,
            'id': id,
            'active': active
        }

    def deletePartition(self, number):
        del self.partitions[number]

    def deletePartitionIfPresent(self, number):
        if number in self.partitions:
            self.deletePartition(number)

    def deletePartitions(self, numbers):
        for number in numbers:
            self.deletePartition(number)

    def renamePartition(self, srcNumber, destNumber, overwrite=False):
        if srcNumber not in self.partitions:
            raise Exception('Source partition '+str(srcNumber)+' does not exist')
        if srcNumber != destNumber:
            if not overwrite and destNumber in self.partitions:
                raise Exception('Destination partition '+str(destNumber)+' already exists')

            self.partitions[destNumber] = self.partitions[srcNumber]
            self.deletePartition(srcNumber)

    def partitionSize(self, number):
        if number not in self.partitions:
            raise Exception('Partition '+str(number)+' does not exist')
        return self.getPartition(number)['size'] * self.sectorSize

    def partitionStart(self, number):
        if number not in self.partitions:
            raise Exception('Partition '+str(number)+' does not exist')
        return self.getPartition(number)['start'] * self.sectorSize

    def partitionEnd(self, number):
        return self.partitionStart(number) + self.partitionSize(number)

    def partitionID(self, number):
        if number not in self.partitions:
            raise Exception('Partition '+str(number)+' does not exist')
        return self.getPartition(number)['id']

    def resizePartition(self, number, sizeBytes):
        if number not in self.partitions:
            raise Exception('Partition for resize '+str(number)+' does not exists')
        if sizeBytes % self.sectorSize != 0:
            raise Exception("Partition size ("+str(sizeBytes)+") is not a multiple of the sector size "+str(self.sectorSize))

        self.partitions[number]['size'] = sizeBytes // self.sectorSize

    def setActiveFlag(self, activeFlag, number):
        assert isinstance(activeFlag, types.BooleanType) # Assert that params are the right way around
        if not number in self.partitions:
            raise Exception('Partition '+str(number)+' does not exist')
        self.partitions[number]['active'] = activeFlag

    def inactivateDisk(self):
        for number, partition in self.partitions.items():
            if partition['active']:
                self.setActiveFlag(False, number)

    def items(self):
        # sorted() creates a new list, so you can delete partitions whilst iterating
        for number, partition in sorted(self.partitions.items()):
            yield number, partition

    def commit(self, dryrun=False, log=False):
        if log:
            self.dump()
        self.writePartitionTable(dryrun, log)
        if not dryrun:
            # Update the revert point so this tool can be used repeatedly
            self.origPartitions = deepcopy(self.partitions)

    def dump(self):
        output  = "Sector size         : "+str(self.sectorSize) + "\n"
        output += "Sector extent       : "+str(self.sectorExtent)+" sectors\n"
        output += "Sector last usable  : "+str(self.sectorLastUsable)+"\n"
        output += "Sector first usable : "+str(self.sectorFirstUsable)+"\n"
        output += "Partition size and start addresses in sectors:\n"
        for number, partition in sorted(self.origPartitions.items()):
            output += "Old partition "+str(number)+":"
            for k, v in sorted(partition.items()):
                output += ' '+k+'='+((k == 'id' and type(v) == int) and hex(v) or str(v))
            output += "\n"
        for number, partition in sorted(self.partitions.items()):
            output += "New partition "+str(number)+":"
            for k, v in sorted(partition.items()):
                output += ' '+k+'='+((k == 'id' and type(v) == int) and hex(v) or str(v))
            output += "\n"
        logger.log(output)


class DOSPartitionTool(PartitionToolBase):

    ID_LINUX_SWAP = 0x82
    ID_LINUX = 0x83
    ID_LINUX_LVM = 0x8e
    ID_DELL_UTILITY = 0xde
    ID_EFI_BOOT = 0xef

    # List of hidden Microsoft partition IDs
    __HIDDEN_MS_IDS = {
        0x11, 0x14, 0x16, 0x17, 0x1b, 0x1c, 0x1e, 0x27
    }

    SFDISK = '/sbin/sfdisk'
    partTableType = constants.PARTITION_DOS

    def __readDiskDetails(self):
        # Read basic geometry
        out = self.cmdWrap([self.SFDISK, '-Lg', self.device])
        matches = re.match(r'^[^:]*:\s*(\d+)\s+cylinders,\s*(\d+)\s+heads,\s*(\d+)\s+sectors', out)
        if not matches:
            raise Exception("Couldn't decode sfdisk output: "+out)
        cylinders = int(matches.group(1))
        heads = int(matches.group(2))
        sectors = int(matches.group(3))
        self.sectorExtent = cylinders * heads * sectors

        # DOS partition tables have 32bit sector addresses so we may need to truncate sectorExtent
        # Actually truncate a bit more because sfdisk has unfathomablely lower limit
        self.sectorExtent = min([self.sectorExtent, 0xffe00000]) # 2047G
        cylinders = int(self.sectorExtent//(heads * sectors))
        self.sectorExtent = cylinders * heads * sectors # Ignore partial cylinder at end

        self.sectorFirstUsable = sectors # Some SANs require bootable disks to start on sector boundary
        self.sectorLastUsable = self.sectorExtent - 1

        # Read sector size
        self.sectorSize = int(self.cmdWrap([self.BLOCKDEV, '--getss', self.device]))

    def __readDeviceMapperDiskDetails(self):
        # DM nodes don't have a geometry and this version of sfdisk will return nothing.
        # Later versions return the default geometry below.
        heads = 255
        sectors = 63
        self.sectorSize = int(self.cmdWrap([self.BLOCKDEV, '--getss', self.device]))
        out = self.cmdWrap([self.BLOCKDEV, '--getsize64', self.device])
        self.sectorExtent = int(out)//self.sectorSize
        # DOS partition tables have 32bit sector addresses so we may need to truncate sectorExtent
        # Actually truncate a bit more because sfdisk has unfathomablely lower limit
        self.sectorExtent = min([self.sectorExtent, 0xffe00000]) # 2047G
        cylinders = int(self.sectorExtent//(heads * sectors))
        self.sectorExtent = cylinders * heads * sectors # Ignore partial cylinder at end
        self.sectorFirstUsable = sectors # Some SANs require bootable disks to start on sector boundary
        self.sectorLastUsable = self.sectorExtent - 1

    def readDiskDetails(self):
        if isDeviceMapperNode(self.device):
            self.__readDeviceMapperDiskDetails()
        else:
            self.__readDiskDetails()

    def partitionTable(self):
        out = self.cmdWrap([self.SFDISK, '-Ld', self.device])
        state = 0
        partitions = {}
        for line in out.split("\n"):
            if line == '' or line[0] == '#':
                pass # Skip comments and blank lines
            elif state == 0:
                if line != 'unit: sectors':
                    raise Exception("Expecting 'unit: sectors' but got '"+line+"'")
                state += 1
            elif state == 1:
                matches = re.match(r'(.*?)\s*:\s*start=\s*(\d+),\s*size=\s*(\d+),\s*Id=\s*(\w+)\s*(,\s*bootable)?', line)
                if matches:
                    idt = int(matches.group(4), 16) # Base 16
                    active = (matches.group(5) is not None)
                else:
                    # extended BSD partition?
                    idt = 0
                    active = False
                    matches = re.match(r'(.*?)\s*:\s*start=\s*(\d+),\s*size=\s*(\d+)', line)
                    if not matches:
                        raise Exception("Could not decode partition line: '"+line+"'")

                size = int(matches.group(3))
                if size != 0: # Treat partitions of size 0 as not present
                    number = self._partitionNumber(matches.group(1))
                    hidden = idt in self.__HIDDEN_MS_IDS

                    partitions[number] = {
                        'start': int(matches.group(2)),
                        'size': size,
                        'id': idt,
                        'active': active,
                        'hidden': hidden
                        }
        return partitions

    def commitActivePartitiontoDisk(self, part_num):
        self.settleUdev()
        self.cmdWrap([self.SFDISK, '--no-reread', '-A%d' % part_num, self.device]) # BIOS bootable flag set for one and unset for others partition
        self.waitForDeviceNodes()

    def writeThisPartitionTable(self, table, dryrun=False, log=False):
        input = 'unit: sectors\n\n'

        # sfdisk doesn't allow us to skip partitions, so invent lines for empty slot
        for number in range(1, 1+max([1]+list(table.keys()))):
            partition = table.get(number, {
                'start': 0,
                'size': 0,
                'id': 0,
                'active': False
            })
            line = self._partitionDevice(number)+' :'
            line += ' start='+str(partition['start'])+','
            line += ' size='+str(partition['size'])+','
            line += ' Id=%x' % partition['id']
            if partition['active']:
                line += ', bootable'

            input += line+'\n'
        if log:
            logger.log('Input to sfdisk:\n'+input)

        if isDeviceMapperNode(self.device):
            # Destroy device mapper partitions before re-writing partition table on mpath device
            rv = destroyPartnodes(self.device)
            if rv:
                raise Exception('Failed to destroy partitions on ' + self.device)
            heads = 255
            sectors = 63
            cylinders = self.sectorExtent//(heads * sectors)
            cmd = [self.SFDISK, dryrun and '-Lnu' or '-Lu', '--no-reread', '-f', '-C%d' % cylinders, '-H%d' % heads, '-S%d' % sectors, self.device]
        else:
            cmd = [self.SFDISK, dryrun and '-LnuS' or '-LuS', '--no-reread', '-f', self.device]
        logger.log('sfdisk command: %s' % ' '.join(cmd))
        self.settleUdev()
        process = subprocess.Popen(
            cmd,
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            stderr=subprocess.STDOUT,
            close_fds=True,
            universal_newlines=True,
            )
        output = process.communicate(input)
        if log:
            logger.log('Output from sfdisk:\n'+output[0])

        if isDeviceMapperNode(self.device):
            # Create partitions using device mapper
            rv = createPartnodes(self.device)
            if rv:
                raise Exception('Failed to create partitions on %s using kpartx ' % self.device)
            for number in table.keys():
                size = int(self.cmdWrap([self.BLOCKDEV, '--getsize64', '%sp%d' % (self.device, number)]))//self.sectorSize
                if size != table[number]['size']:
                    raise Exception('Failed to create partition %sp%d of size %d' % (self.device, number, table[number]['size']))

        else:
            if process.returncode != 0:
                raise Exception('Partition changes could not be applied: '+str(output[0]))

            # CA-35300: sfdisk doesn't return non-zero when the BLKRRPART ioctl fails
            if 'BLKRRPART: Device or resource busy' in output:
                raise Exception('The disk appears to be in use and partition changes cannot be applied. Reboot and repeat the installation')

            # Verify the table
            # Ignore warnings about partitions apparently with ends beyond the end of the disk
            rc, err = util.runCmd2([self.SFDISK, '-LVquS', self.device], with_stderr=True)
            if rc == 1:
                lines = err.split('\n')
                if len([x for x in lines if x != '' and not x.endswith('extends past end of disk')]) != 0:
                    raise Exception(err)
            elif rc != 0:
                raise Exception(err)

    def utilityPartitions(self):
        # Return list of partition numbers for partitions we should preserve
        return [num for num in self.partitions.keys() if self.partitions[num]['id'] == self.ID_DELL_UTILITY]

    def convertToGPT(self):
        self.cmdWrap(['sgdisk', '--mbrtogpt', self.device])

        gpt_tool = GPTPartitionTool(self.device)

        # Copy hidden attribute on MS partitions
        hidden_args = []
        for num, part in self.partitions.items():
            if part['id'] in self.__HIDDEN_MS_IDS and gpt_tool.partitions[num]['id'] == gpt_tool.ID_LINUX:
                hidden_args.append('--attributes=%d:set:62' % num)
                gpt_tool.partitions[num]['hidden'] = True
        if hidden_args:
            self.cmdWrap([gpt_tool.SGDISK] + hidden_args + [self.device])

        return gpt_tool


class GPTPartitionTool(PartitionToolBase):

    # These are partition type GUIDs
    ID_LINUX_SWAP   = "0657FD6D-A4AB-43C4-84E5-0933C84B4F4F"
    ID_LINUX        = "EBD0A0A2-B9E5-4433-87C0-68B6B72699C7"
    ID_LINUX_LVM    = "E6D6D379-F507-44C2-A23C-238F2A3DF928"
    ID_EFI_BOOT     = "C12A7328-F81F-11D2-BA4B-00A0C93EC93B"
    ID_BIOS_BOOT    = "21686148-6449-6E6F-744E-656564454649"

    # Lookup used for creating partitions
    GUID_to_type_code = {
        ID_LINUX_SWAP:   '8200',
        ID_LINUX:        '0700',
        ID_LINUX_LVM:    '8e00',
        ID_EFI_BOOT:     'ef00',
        ID_BIOS_BOOT:    'ef02',
        }

    SGDISK = 'sgdisk'
    partTableType = constants.PARTITION_GPT

    def readDiskDetails(self):
        self.sectorSize        = int(self.cmdWrap([self.BLOCKDEV, '--getss', self.device]))
        self.sectorExtent      = int(self.cmdWrap([self.BLOCKDEV, '--getsize64', self.device])) // self.sectorSize
        # size depends on GPT entries (should be 128), their size (128 bytes) and sector size
        # first sector is MBR, second GPT header
        self.sectorFirstUsable = 2 - (-128*128 // self.sectorSize)
        self.sectorLastUsable  = self.sectorExtent - self.sectorFirstUsable
        self.sectorAlignment   = 2 ** 20 // self.sectorSize

    def partitionTable(self):
        cmd = [self.SGDISK, '--print', self.device]
        rv, out, err = util.runCmd2(cmd, True, True)
        if rv != 0:
            logger.log('Invalid or corrupt partition table found on disk %s. Skipping...' % self.device)
            self.waitForDeviceNodes()
            return {}

        matchWarning   = re.compile('Found invalid GPT and valid MBR; converting MBR to GPT format.')
        matchHeader    = re.compile('Number\s+Start \(sector\)\s+End \(sector\)\s+Size\s+Code\s+Name')
        matchPartition = re.compile('^\s+(\d+)\s+(\d+)\s+(\d+)\s+([\d.]+\s+\w+)\s+([0-9A-F]{4})(\s+(.*))?$') # num start end sz typecode name
        matchActive    = re.compile('.*\(legacy BIOS bootable\)')
        matchHidden    = re.compile('.*\(hidden\)')
        matchId        = re.compile('^Partition GUID code: ([0-9A-F\-]+) ')
        matchPartUUID  = re.compile('^Partition unique GUID: ([0-9A-F\-]+)$')
        partitions = {}
        lines = out.split('\n')
        gotHeader = False
        for line in lines:
            if not line.strip():
                continue
            if not gotHeader:
                if matchWarning.match(line):
                    logger.log("Warning: GPTPartitionTool found DOS partition table on device %s" % self.device)
                elif matchHeader.match(line):
                    gotHeader = True
            else:
                matches = matchPartition.match(line)
                if not matches:
                    raise Exception("Could not parse sgdisk output line: %s" % line)
                number  = int(matches.group(1))
                start   = int(matches.group(2))
                _end    = int(matches.group(3))
                size    = _end + 1 - start
                partlabel = matches.group(7) if matches.group(7) else ''
                partitions[number] = {
                    'start': int(matches.group(2)),
                    'size': size,
                    'partlabel': partlabel,
                    }
        # For each partition determine the active state.
        # By active we mean "BIOS bootable"
        for number in partitions:
            out = self.cmdWrap([self.SGDISK, '--attributes=%d:show' % number, self.device])
            partitions[number]['active'] = matchActive.match(out) and True or False
            partitions[number]['hidden'] = matchHidden.match(out) and True or False
            out = self.cmdWrap([self.SGDISK, '--info=%d' % number, self.device])
            for line in out.split('\n'):
                m = matchId.match(line)
                if m:
                    partitions[number]['id'] = m.group(1)
                m = matchPartUUID.match(line)
                if m:
                    partitions[number]['partuuid'] = m.group(1)
            assert 'id' in partitions[number]

        # sgdisk opens the device with O_WRONLY even when not changing anything
        # so settle udev to ensure device nodes are available for subsequent
        # commands.
        self.waitForDeviceNodes()
        return partitions

    def commitActivePartitiontoDisk(self, partnum):
        args = []
        for num, part in self.items():
            if num == partnum:
                args += ['--attributes=%d:set:2' % num] # BIOS bootable flag set
            else:
                args += ['--attributes=%d:clear:2' % num] # BIOS bootable flag clear

        if args:
            self.cmdWrap([self.SGDISK] + args + [self.device])

        self.waitForDeviceNodes()

    def writeThisPartitionTable(self, table, dryrun=False, log=False):
        for part in table.values():
            if part['id'] not in self.GUID_to_type_code:
                raise Exception("GPT partitions with part type GUID %s unsupported" % part['id'])

        if isDeviceMapperNode(self.device):
            # Destroy device mapper partitions before re-writing partition table on mpath device
            rv = destroyPartnodes(self.device)
            if rv:
                raise Exception('Failed to destroy GPT partitions on ' + self.device)

        # Bring us to a known state.
        try:
            # --clear is called to clear the backup GPT first, since --zap does not clear this and
            # will restore the backup GPT if the main GPT is damaged (which is not what we want).
            self.cmdWrap([self.SGDISK, '--clear', self.device])
        except:
            # Ignore error code which results from inconsistent initial state
            pass

        try:
            self.cmdWrap([self.SGDISK, '--zap', self.device])
        except:
            # Ignore error code which results from inconsistent initial state
            pass
        self.cmdWrap([self.SGDISK, '--mbrtogpt', '--clear', self.device])

        has_esp = False
        for part in table.values():
            if part['id'] == self.ID_EFI_BOOT:
                has_esp = True
                break

        if not has_esp:
            # CA-54144: Some _stupid_ BIOSes refuse to boot disks that don't have a DOS partition table
            # with an active partition.  This is incorrect because it makes the assumption that the
            # bootloader uses a DOS partition table.  Instead the BIOSes _should_ just check for 0x55,0xaa
            # at location 0x1fe.
            # However, let's keep them happy by making the single partition in the protective MBR "active".
            self.settleUdev()
            self.cmdWrap(['sfdisk', '--no-reread', '-A1', self.device])

        # Ensure that we write out in on-disk order to prevent conflicts when
        # partition sizes get rounded.
        args = [self.SGDISK, '--set-alignment=1']
        items = sorted(table.items(), key=lambda item: item[1]['start'])
        for num,part in items:
            start  = part['start']
            end    = part['size'] + start - 1
            idt    = part['id']
            active = part['active']
            hidden = part.get('hidden', False)
            args += ['--new=%d:%d:%d' % (num,start,end)]
            args += ['--typecode=%d:%s' % (num,self.GUID_to_type_code[idt])]
            if active:
                args += ['--attributes=%d:set:2' % num] # BIOS bootable flag
            if hidden and idt == self.ID_LINUX:
                args += ['--attributes=%d:set:62' % num] # hidden flag
            if 'partlabel' in part and part['partlabel']:
                args += ['--change-name=%d:%s' % (num,part['partlabel'])]
            if 'partuuid' in part:
                args += ['--partition-guid=%d:%s' % (num,part['partuuid'])]
        args += [self.device]
        self.cmdWrap(args)

        if isDeviceMapperNode(self.device):
            # Create partitions using device mapper
            rv = createPartnodes(self.device)
            if rv:
                raise Exception('Failed to create partitions on %s using kpartx ' % self.device)

    def utilityPartitions(self):
        # Return list of partition numbers for partitions we should preserve
        return [num for num in self.partitions.keys() if
                self.partitions[num]['id'] == self.ID_EFI_BOOT and self.partitions[num]['partlabel'] == constants.UTILITY_PARTLABEL]

def probePartitioningScheme(device):
    """Determine whether the MBR is a DOS MBR, or a GPT PMBR"""
    partitionType = constants.PARTITION_GPT   # default
    rv, out = util.runCmd2(['blkid', '-s', 'PTTYPE', '-o', 'value', device], with_stdout=True)
    out = out.strip()

    if out == 'dos':
        partitionType = constants.PARTITION_DOS

    logger.debug("probePartitioningScheme(%r) => %r", device, partitionType)
    return partitionType

def PartitionTool(device, partitionType=None):
    """
    By default PartitionTool() will return the tool appropriate to the partitioning
    system currently in use on device
    """
    if partitionType is None:
        partitionType = probePartitioningScheme(device)
    if partitionType == constants.PARTITION_DOS:
        return DOSPartitionTool(device)
    elif partitionType == constants.PARTITION_GPT:
        return GPTPartitionTool(device)

def destroyPartnodes(dev):
    # Destroy partition nodes for a device-mapper device
    dmnodes = [ '/dev/mapper/%s' % f for f in os.listdir('/dev/mapper') ]
    partitions = [dmnode for dmnode in dmnodes if re.match(dev + r'p?\d+$', dmnode)]
    for partition in partitions:
        # the obvious way to do this is to use "kpartx -d" but that's broken!
        rv = util.runCmd2(['dmsetup', 'remove', partition])
        if rv: return rv
    return 0

def destroyMpathPartnodes():
    mpnodes = getMpathNodes()
    for mpnode in mpnodes:
        rv = destroyPartnodes(mpnode)
        if rv: return rv
    return 0

def createPartnodes(dev):
    # Create partition nodes for a device-mapper device
    return util.runCmd2(['kpartx', '-a', dev])

def createMpathPartnodes():
    return util.runCmd2(['dmsetup', 'ls', '--target', 'multipath', '--exec', "kpartx -a"])

def getMpathNodes():
    nodes = []
    rv, out = util.runCmd2(['dmsetup', 'ls', '--target', 'multipath', '--exec', 'ls'], with_stdout=True)
    logger.log("multipath devs: %s" % out)
    lines = out.strip().split('\n')
    for line in lines:
        if line.startswith('/dev/'):
            nodes.append(line)
    return nodes

def getMajMin(dev):
    buf = os.stat(dev)
    major = os.major(buf.st_rdev)
    minor = os.minor(buf.st_rdev)
    return (major, minor)

cached_DM_maj = None
def getDeviceMapperMaj():
    global cached_DM_maj
    if not cached_DM_maj:
        try:
            line = [x for x in open('/proc/devices').readlines() if x.endswith('device-mapper\n')]
            cached_DM_maj = int(line[0].split()[0])
        except:
            pass
    return cached_DM_maj

def isDeviceMapperNode(dev):
    try:
        return getMajMin(dev)[0] == getDeviceMapperMaj()
    except OSError:
        return False

def getSysfsDir(dev):
    major, minor = getMajMin(dev)
    parts = open("/proc/partitions")
    partlines = [re.sub(" +", " ", x).strip() for x in parts.readlines()]
    parts.close()
    # parse it:
    disks = []
    for l in partlines:
        try:
           (_major, _minor, size, name) = l.split(" ")
           if (major, minor) == (int(_major), int(_minor)):
               name = name.replace('/','!')
               return '/sys/block/%s' % name
        except:
            pass
    raise RuntimeError("Couldn't find sysfs dir for device %s" % dev)

def hasDeviceMapperHolder(dev):
    sysfs = getSysfsDir(dev)
    if os.path.exists('%s/holders' % sysfs):
        for holder in os.listdir('%s/holders' % sysfs):
            if holder.startswith('dm-'):
                return True
    return False


def getDeviceMapperNode(n):
    "Return the /dev/mapper/node corresponding to /sys/block/dm-n"
    (major,minor) = map(int,open('/sys/block/dm-%s/dev' % str(n)).read().strip().split(':'))
    for i in os.listdir('/dev/mapper'):
        dmdev = '/dev/mapper/%s' % i
        if getMajMin(dmdev) == (major,minor):
            return dmdev
    return None


def getDeviceSlaves(disk):
    """ Return the list of slaves for an device or an empty list """
    slaves = []
    major, minor = getMajMin(disk)
    rv, out = util.runCmd2(['sh','-c','ls -d1 /sys/block/*/holders/*/dev'],with_stdout=True)
    lines = out.strip().split('\n')
    lines = [x for x in lines if x != '']
    for f in lines:
        _, _, _, dev, _, _, _ = f.split('/')
        __major, __minor = map(int, open(f).read().split(':'))
        if (__major, __minor) == (major, minor):
            dev = '/dev/' + dev.replace("!", "/")
            slaves.append(dev)
    return slaves

def getMpathMaster(dev):
    "Returns master device or None"
    try:
        d = getSysfsDir(dev)

        if dev.startswith('/dev/dm-'):
            holder = dev[5:]
        else:
            holders = os.listdir('%s/holders' % d)
            if len(holders) != 1 or (not holders[0].startswith('dm-')):
                logger.log('getMpathMaster: contents of %s/holders/ is %s' % (d,str(holders)))
                return None
            else:
                holder = holders[0]

        (major,minor) = map(int,open('/sys/block/%s/dev' % holder).read().strip().split(':'))
        for i in os.listdir('/dev/mapper'):
            dmdev = '/dev/mapper/%s' % i
            if getMajMin(dmdev) == (major,minor):
                logger.log('getMpathMaster: %s has master %s' % (dev,dmdev))
                return dmdev
        logger.log('getMpathMaster: could not find master %d:%d of %s in /dev/mapper/' % (major,minor,dev))

    except OSError:
        return None

def getMpathMasterOrDisk(disk):
    """Returns the multipath master or the original device if it is not part of
    a multipath setup."""

    master = getMpathMaster(disk)
    return master if master else disk

def getMdNodes():
    nodes = []
    try:
        fh = open('/proc/mdstat')
        for line in fh:
            line = line.rstrip()
            if not ' : ' in line:
                continue
            l = line.split(None, 3)
            if l[2] == 'active':
                nodes.append('/dev/'+l[0])
        fh.close()
    except IOError:
        pass
    return nodes


class DeviceMounter:
    class Mount:
        def __init__(self, dev, mountpoint, options=None, fstype=None):
            self.dev = dev
            self.mountpoint = mountpoint
            self.options = options
            self.fstype = fstype

        def __repr__(self):
            return "Mount(%s, %s, %s, %s)" % (self.dev, self.mountpoint, self.fstype, self.options)

        def mount(self):
            try:
                os.makedirs(self.mountpoint, mode=0o755)
            except OSError as e:
                if e.errno != errno.EEXIST:
                    raise

            util.mount(self.dev, self.mountpoint, self.options, self.fstype)

        def umount(self):
            util.umount(self.mountpoint)

    mounts = []

    @classmethod
    def addMountPoints(cls, arg_mounts):
        mounts = []
        for arg in arg_mounts:
            m = arg.split(':')
            if len(m) < 2:
                continue
            dev = m[0]
            fstype = None
            options = None
            if len(m) > 4:
                raise Exception("Invalid syntax for --mount argument: %s" % arg)
            if len(m) == 4:
                fstype = m[1]
                options = m[2]
                mnt = m[3]
            elif len(m) >= 3:
                fstype = m[1]
                mnt = m[2]
            else:
                mnt = m[1]
            if dev.startswith("LABEL=") or dev.startswith("UUID="):
                rc, out = util.runCmd2(['blkid', '-t', dev, '-o', 'device'], with_stdout=True)
                if rc != 0:
                    # for compatibility ignore the device
                    continue
                dev = out.rstrip()
            elif dev.startswith("VG_"):
                rc = util.runCmd2(LVMTool.LVCHANGE + ['-a', 'y', dev])
                if rc != 0:
                    # for compatibility ignore the device
                    continue
                dev = dev.replace("-", "--")
                vg, lv, _ = (dev + "//").split("/", 2)
                dev = "/dev/mapper/%s-%s" % (vg, lv)
            mounts.append(cls.Mount(dev, mnt, options, fstype))
        cls.mounts = mounts

    def __init__(self):
        self.mounts = self.__class__.mounts

    def mount(self):
        for m in self.mounts:
            try:
                m.mount()
            except Exception as e:
                logger.logException(e)

    def __umount(self):
        for m in self.mounts:
            try:
                m.umount()
            except Exception as e:
                logger.logException(e)

    def __enter__(self):
        self.mount()

    def __exit__(self, type, value, traceback):
        self.__umount()