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#
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#

# Copyright (C) 2006, 2007 Google Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.


"""Block device abstraction"""

import re
import time
import errno
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import pyparsing as pyp
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import os
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import logging
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from ganeti import utils
from ganeti import errors
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from ganeti import constants
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from ganeti import objects
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# Size of reads in _CanReadDevice
_DEVICE_READ_SIZE = 128 * 1024


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def _IgnoreError(fn, *args, **kwargs):
  """Executes the given function, ignoring BlockDeviceErrors.

  This is used in order to simplify the execution of cleanup or
  rollback functions.

  @rtype: boolean
  @return: True when fn didn't raise an exception, False otherwise

  """
  try:
    fn(*args, **kwargs)
    return True
  except errors.BlockDeviceError, err:
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    logging.warning("Caught BlockDeviceError but ignoring: %s", str(err))
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    return False


def _ThrowError(msg, *args):
  """Log an error to the node daemon and the raise an exception.

  @type msg: string
  @param msg: the text of the exception
  @raise errors.BlockDeviceError

  """
  if args:
    msg = msg % args
  logging.error(msg)
  raise errors.BlockDeviceError(msg)


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def _CanReadDevice(path):
  """Check if we can read from the given device.

  This tries to read the first 128k of the device.

  """
  try:
    utils.ReadFile(path, size=_DEVICE_READ_SIZE)
    return True
  except EnvironmentError, err:
    logging.warning("Can't read from device %s", path, exc_info=True)
    return False


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class BlockDev(object):
  """Block device abstract class.

  A block device can be in the following states:
    - not existing on the system, and by `Create()` it goes into:
    - existing but not setup/not active, and by `Assemble()` goes into:
    - active read-write and by `Open()` it goes into
    - online (=used, or ready for use)

  A device can also be online but read-only, however we are not using
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  the readonly state (LV has it, if needed in the future) and we are
  usually looking at this like at a stack, so it's easier to
  conceptualise the transition from not-existing to online and back
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  like a linear one.

  The many different states of the device are due to the fact that we
  need to cover many device types:
    - logical volumes are created, lvchange -a y $lv, and used
    - drbd devices are attached to a local disk/remote peer and made primary

  A block device is identified by three items:
    - the /dev path of the device (dynamic)
    - a unique ID of the device (static)
    - it's major/minor pair (dynamic)

  Not all devices implement both the first two as distinct items. LVM
  logical volumes have their unique ID (the pair volume group, logical
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  volume name) in a 1-to-1 relation to the dev path. For DRBD devices,
  the /dev path is again dynamic and the unique id is the pair (host1,
  dev1), (host2, dev2).
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  You can get to a device in two ways:
    - creating the (real) device, which returns you
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      an attached instance (lvcreate)
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    - attaching of a python instance to an existing (real) device

  The second point, the attachement to a device, is different
  depending on whether the device is assembled or not. At init() time,
  we search for a device with the same unique_id as us. If found,
  good. It also means that the device is already assembled. If not,
  after assembly we'll have our correct major/minor.

  """
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  def __init__(self, unique_id, children, size):
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    self._children = children
    self.dev_path = None
    self.unique_id = unique_id
    self.major = None
    self.minor = None
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    self.attached = False
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    self.size = size
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  def Assemble(self):
    """Assemble the device from its components.

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    Implementations of this method by child classes must ensure that:
      - after the device has been assembled, it knows its major/minor
        numbers; this allows other devices (usually parents) to probe
        correctly for their children
      - calling this method on an existing, in-use device is safe
      - if the device is already configured (and in an OK state),
        this method is idempotent
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    """
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    pass
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  def Attach(self):
    """Find a device which matches our config and attach to it.

    """
    raise NotImplementedError

  def Close(self):
    """Notifies that the device will no longer be used for I/O.

    """
    raise NotImplementedError

  @classmethod
  def Create(cls, unique_id, children, size):
    """Create the device.

    If the device cannot be created, it will return None
    instead. Error messages go to the logging system.

    Note that for some devices, the unique_id is used, and for other,
    the children. The idea is that these two, taken together, are
    enough for both creation and assembly (later).

    """
    raise NotImplementedError

  def Remove(self):
    """Remove this device.

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    This makes sense only for some of the device types: LV and file
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    storage. Also note that if the device can't attach, the removal
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    can't be completed.
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    """
    raise NotImplementedError

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  def Rename(self, new_id):
    """Rename this device.

    This may or may not make sense for a given device type.

    """
    raise NotImplementedError

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  def Open(self, force=False):
    """Make the device ready for use.

    This makes the device ready for I/O. For now, just the DRBD
    devices need this.

    The force parameter signifies that if the device has any kind of
    --force thing, it should be used, we know what we are doing.

    """
    raise NotImplementedError

  def Shutdown(self):
    """Shut down the device, freeing its children.

    This undoes the `Assemble()` work, except for the child
    assembling; as such, the children on the device are still
    assembled after this call.

    """
    raise NotImplementedError

  def SetSyncSpeed(self, speed):
    """Adjust the sync speed of the mirror.

    In case this is not a mirroring device, this is no-op.

    """
    result = True
    if self._children:
      for child in self._children:
        result = result and child.SetSyncSpeed(speed)
    return result

  def GetSyncStatus(self):
    """Returns the sync status of the device.

    If this device is a mirroring device, this function returns the
    status of the mirror.

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    If sync_percent is None, it means the device is not syncing.
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    If estimated_time is None, it means we can't estimate
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    the time needed, otherwise it's the time left in seconds.

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    If is_degraded is True, it means the device is missing
    redundancy. This is usually a sign that something went wrong in
    the device setup, if sync_percent is None.

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    The ldisk parameter represents the degradation of the local
    data. This is only valid for some devices, the rest will always
    return False (not degraded).

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    @rtype: objects.BlockDevStatus
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    """
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    return objects.BlockDevStatus(dev_path=self.dev_path,
                                  major=self.major,
                                  minor=self.minor,
                                  sync_percent=None,
                                  estimated_time=None,
                                  is_degraded=False,
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                                  ldisk_status=constants.LDS_OKAY)
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  def CombinedSyncStatus(self):
    """Calculate the mirror status recursively for our children.

    The return value is the same as for `GetSyncStatus()` except the
    minimum percent and maximum time are calculated across our
    children.

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    @rtype: objects.BlockDevStatus

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    """
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    status = self.GetSyncStatus()

    min_percent = status.sync_percent
    max_time = status.estimated_time
    is_degraded = status.is_degraded
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    ldisk_status = status.ldisk_status
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    if self._children:
      for child in self._children:
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        child_status = child.GetSyncStatus()

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        if min_percent is None:
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          min_percent = child_status.sync_percent
        elif child_status.sync_percent is not None:
          min_percent = min(min_percent, child_status.sync_percent)

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        if max_time is None:
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          max_time = child_status.estimated_time
        elif child_status.estimated_time is not None:
          max_time = max(max_time, child_status.estimated_time)

        is_degraded = is_degraded or child_status.is_degraded
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        if ldisk_status is None:
          ldisk_status = child_status.ldisk_status
        elif child_status.ldisk_status is not None:
          ldisk_status = max(ldisk_status, child_status.ldisk_status)
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    return objects.BlockDevStatus(dev_path=self.dev_path,
                                  major=self.major,
                                  minor=self.minor,
                                  sync_percent=min_percent,
                                  estimated_time=max_time,
                                  is_degraded=is_degraded,
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                                  ldisk_status=ldisk_status)
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  def SetInfo(self, text):
    """Update metadata with info text.

    Only supported for some device types.

    """
    for child in self._children:
      child.SetInfo(text)

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  def Grow(self, amount):
    """Grow the block device.

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    @param amount: the amount (in mebibytes) to grow with
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    """
    raise NotImplementedError
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  def GetActualSize(self):
    """Return the actual disk size.

    @note: the device needs to be active when this is called

    """
    assert self.attached, "BlockDevice not attached in GetActualSize()"
    result = utils.RunCmd(["blockdev", "--getsize64", self.dev_path])
    if result.failed:
      _ThrowError("blockdev failed (%s): %s",
                  result.fail_reason, result.output)
    try:
      sz = int(result.output.strip())
    except (ValueError, TypeError), err:
      _ThrowError("Failed to parse blockdev output: %s", str(err))
    return sz

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  def __repr__(self):
    return ("<%s: unique_id: %s, children: %s, %s:%s, %s>" %
            (self.__class__, self.unique_id, self._children,
             self.major, self.minor, self.dev_path))


class LogicalVolume(BlockDev):
  """Logical Volume block device.

  """
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  def __init__(self, unique_id, children, size):
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    """Attaches to a LV device.

    The unique_id is a tuple (vg_name, lv_name)

    """
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    super(LogicalVolume, self).__init__(unique_id, children, size)
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    if not isinstance(unique_id, (tuple, list)) or len(unique_id) != 2:
      raise ValueError("Invalid configuration data %s" % str(unique_id))
    self._vg_name, self._lv_name = unique_id
    self.dev_path = "/dev/%s/%s" % (self._vg_name, self._lv_name)
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    self._degraded = True
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    self.major = self.minor = self.pe_size = self.stripe_count = None
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    self.Attach()

  @classmethod
  def Create(cls, unique_id, children, size):
    """Create a new logical volume.

    """
    if not isinstance(unique_id, (tuple, list)) or len(unique_id) != 2:
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      raise errors.ProgrammerError("Invalid configuration data %s" %
                                   str(unique_id))
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    vg_name, lv_name = unique_id
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    pvs_info = cls.GetPVInfo([vg_name])
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    if not pvs_info:
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      _ThrowError("Can't compute PV info for vg %s", vg_name)
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    pvs_info.sort()
    pvs_info.reverse()
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    pvlist = [ pv[1] for pv in pvs_info ]
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    if utils.any(pvlist, lambda v: ":" in v):
      _ThrowError("Some of your PVs have invalid character ':'"
                  " in their name")
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    free_size = sum([ pv[0] for pv in pvs_info ])
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    current_pvs = len(pvlist)
    stripes = min(current_pvs, constants.LVM_STRIPECOUNT)
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    # The size constraint should have been checked from the master before
    # calling the create function.
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    if free_size < size:
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      _ThrowError("Not enough free space: required %s,"
                  " available %s", size, free_size)
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    cmd = ["lvcreate", "-L%dm" % size, "-n%s" % lv_name]
    # If the free space is not well distributed, we won't be able to
    # create an optimally-striped volume; in that case, we want to try
    # with N, N-1, ..., 2, and finally 1 (non-stripped) number of
    # stripes
    for stripes_arg in range(stripes, 0, -1):
      result = utils.RunCmd(cmd + ["-i%d" % stripes_arg] + [vg_name] + pvlist)
      if not result.failed:
        break
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    if result.failed:
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      _ThrowError("LV create failed (%s): %s",
                  result.fail_reason, result.output)
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    return LogicalVolume(unique_id, children, size)
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  @staticmethod
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  def GetPVInfo(vg_names, filter_allocatable=True):
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    """Get the free space info for PVs in a volume group.

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    @param vg_names: list of volume group names, if empty all will be returned
    @param filter_allocatable: whether to skip over unallocatable PVs
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    @rtype: list
    @return: list of tuples (free_space, name) with free_space in mebibytes
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    """
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    sep = "|"
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    command = ["pvs", "--noheadings", "--nosuffix", "--units=m",
               "-opv_name,vg_name,pv_free,pv_attr", "--unbuffered",
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               "--separator=%s" % sep ]
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    result = utils.RunCmd(command)
    if result.failed:
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      logging.error("Can't get the PV information: %s - %s",
                    result.fail_reason, result.output)
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      return None
    data = []
    for line in result.stdout.splitlines():
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      fields = line.strip().split(sep)
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      if len(fields) != 4:
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        logging.error("Can't parse pvs output: line '%s'", line)
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        return None
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      # (possibly) skip over pvs which are not allocatable
      if filter_allocatable and fields[3][0] != 'a':
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        continue
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      # (possibly) skip over pvs which are not in the right volume group(s)
      if vg_names and fields[1] not in vg_names:
        continue
      data.append((float(fields[2]), fields[0], fields[1]))
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    return data

  def Remove(self):
    """Remove this logical volume.

    """
    if not self.minor and not self.Attach():
      # the LV does not exist
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      return
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    result = utils.RunCmd(["lvremove", "-f", "%s/%s" %
                           (self._vg_name, self._lv_name)])
    if result.failed:
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      _ThrowError("Can't lvremove: %s - %s", result.fail_reason, result.output)
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  def Rename(self, new_id):
    """Rename this logical volume.

    """
    if not isinstance(new_id, (tuple, list)) or len(new_id) != 2:
      raise errors.ProgrammerError("Invalid new logical id '%s'" % new_id)
    new_vg, new_name = new_id
    if new_vg != self._vg_name:
      raise errors.ProgrammerError("Can't move a logical volume across"
                                   " volume groups (from %s to to %s)" %
                                   (self._vg_name, new_vg))
    result = utils.RunCmd(["lvrename", new_vg, self._lv_name, new_name])
    if result.failed:
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      _ThrowError("Failed to rename the logical volume: %s", result.output)
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    self._lv_name = new_name
    self.dev_path = "/dev/%s/%s" % (self._vg_name, self._lv_name)

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  def Attach(self):
    """Attach to an existing LV.

    This method will try to see if an existing and active LV exists
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    which matches our name. If so, its major/minor will be
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    recorded.

    """
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    self.attached = False
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    result = utils.RunCmd(["lvs", "--noheadings", "--separator=,",
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                           "--units=m", "--nosuffix",
                           "-olv_attr,lv_kernel_major,lv_kernel_minor,"
                           "vg_extent_size,stripes", self.dev_path])
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    if result.failed:
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      logging.error("Can't find LV %s: %s, %s",
                    self.dev_path, result.fail_reason, result.output)
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      return False
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    # the output can (and will) have multiple lines for multi-segment
    # LVs, as the 'stripes' parameter is a segment one, so we take
    # only the last entry, which is the one we're interested in; note
    # that with LVM2 anyway the 'stripes' value must be constant
    # across segments, so this is a no-op actually
    out = result.stdout.splitlines()
    if not out: # totally empty result? splitlines() returns at least
                # one line for any non-empty string
      logging.error("Can't parse LVS output, no lines? Got '%s'", str(out))
      return False
    out = out[-1].strip().rstrip(',')
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    out = out.split(",")
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    if len(out) != 5:
      logging.error("Can't parse LVS output, len(%s) != 5", str(out))
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      return False

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    status, major, minor, pe_size, stripes = out
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    if len(status) != 6:
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      logging.error("lvs lv_attr is not 6 characters (%s)", status)
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      return False

    try:
      major = int(major)
      minor = int(minor)
    except ValueError, err:
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      logging.error("lvs major/minor cannot be parsed: %s", str(err))
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    try:
      pe_size = int(float(pe_size))
    except (TypeError, ValueError), err:
      logging.error("Can't parse vg extent size: %s", err)
      return False

    try:
      stripes = int(stripes)
    except (TypeError, ValueError), err:
      logging.error("Can't parse the number of stripes: %s", err)
      return False

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    self.major = major
    self.minor = minor
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    self.pe_size = pe_size
    self.stripe_count = stripes
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    self._degraded = status[0] == 'v' # virtual volume, i.e. doesn't backing
                                      # storage
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    self.attached = True
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    return True
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  def Assemble(self):
    """Assemble the device.

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    We always run `lvchange -ay` on the LV to ensure it's active before
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    use, as there were cases when xenvg was not active after boot
    (also possibly after disk issues).
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    """
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    result = utils.RunCmd(["lvchange", "-ay", self.dev_path])
    if result.failed:
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      _ThrowError("Can't activate lv %s: %s", self.dev_path, result.output)
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  def Shutdown(self):
    """Shutdown the device.

    This is a no-op for the LV device type, as we don't deactivate the
    volumes on shutdown.

    """
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    pass
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  def GetSyncStatus(self):
    """Returns the sync status of the device.

    If this device is a mirroring device, this function returns the
    status of the mirror.

    For logical volumes, sync_percent and estimated_time are always
    None (no recovery in progress, as we don't handle the mirrored LV
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    case). The is_degraded parameter is the inverse of the ldisk
    parameter.
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    For the ldisk parameter, we check if the logical volume has the
    'virtual' type, which means it's not backed by existing storage
    anymore (read from it return I/O error). This happens after a
    physical disk failure and subsequent 'vgreduce --removemissing' on
    the volume group.
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    The status was already read in Attach, so we just return it.

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    @rtype: objects.BlockDevStatus
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    """
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    if self._degraded:
      ldisk_status = constants.LDS_FAULTY
    else:
      ldisk_status = constants.LDS_OKAY

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    return objects.BlockDevStatus(dev_path=self.dev_path,
                                  major=self.major,
                                  minor=self.minor,
                                  sync_percent=None,
                                  estimated_time=None,
                                  is_degraded=self._degraded,
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                                  ldisk_status=ldisk_status)
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  def Open(self, force=False):
    """Make the device ready for I/O.

    This is a no-op for the LV device type.

    """
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    pass
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  def Close(self):
    """Notifies that the device will no longer be used for I/O.

    This is a no-op for the LV device type.

    """
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    pass
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  def Snapshot(self, size):
    """Create a snapshot copy of an lvm block device.

    """
    snap_name = self._lv_name + ".snap"

    # remove existing snapshot if found
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    snap = LogicalVolume((self._vg_name, snap_name), None, size)
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    _IgnoreError(snap.Remove)
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    pvs_info = self.GetPVInfo([self._vg_name])
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    if not pvs_info:
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      _ThrowError("Can't compute PV info for vg %s", self._vg_name)
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    pvs_info.sort()
    pvs_info.reverse()
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    free_size, pv_name, _ = pvs_info[0]
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    if free_size < size:
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      _ThrowError("Not enough free space: required %s,"
                  " available %s", size, free_size)
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    result = utils.RunCmd(["lvcreate", "-L%dm" % size, "-s",
                           "-n%s" % snap_name, self.dev_path])
    if result.failed:
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      _ThrowError("command: %s error: %s - %s",
                  result.cmd, result.fail_reason, result.output)
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    return snap_name

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  def SetInfo(self, text):
    """Update metadata with info text.

    """
    BlockDev.SetInfo(self, text)

    # Replace invalid characters
    text = re.sub('^[^A-Za-z0-9_+.]', '_', text)
    text = re.sub('[^-A-Za-z0-9_+.]', '_', text)

    # Only up to 128 characters are allowed
    text = text[:128]

    result = utils.RunCmd(["lvchange", "--addtag", text,
                           self.dev_path])
    if result.failed:
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      _ThrowError("Command: %s error: %s - %s", result.cmd, result.fail_reason,
                  result.output)

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  def Grow(self, amount):
    """Grow the logical volume.

    """
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    if self.pe_size is None or self.stripe_count is None:
      if not self.Attach():
        _ThrowError("Can't attach to LV during Grow()")
    full_stripe_size = self.pe_size * self.stripe_count
    rest = amount % full_stripe_size
    if rest != 0:
      amount += full_stripe_size - rest
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    # we try multiple algorithms since the 'best' ones might not have
    # space available in the right place, but later ones might (since
    # they have less constraints); also note that only recent LVM
    # supports 'cling'
    for alloc_policy in "contiguous", "cling", "normal":
      result = utils.RunCmd(["lvextend", "--alloc", alloc_policy,
                             "-L", "+%dm" % amount, self.dev_path])
      if not result.failed:
        return
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    _ThrowError("Can't grow LV %s: %s", self.dev_path, result.output)
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class DRBD8Status(object):
  """A DRBD status representation class.

  Note that this doesn't support unconfigured devices (cs:Unconfigured).

  """
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  UNCONF_RE = re.compile(r"\s*[0-9]+:\s*cs:Unconfigured$")
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  LINE_RE = re.compile(r"\s*[0-9]+:\s*cs:(\S+)\s+(?:st|ro):([^/]+)/(\S+)"
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                       "\s+ds:([^/]+)/(\S+)\s+.*$")
  SYNC_RE = re.compile(r"^.*\ssync'ed:\s*([0-9.]+)%.*"
                       "\sfinish: ([0-9]+):([0-9]+):([0-9]+)\s.*$")

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  CS_UNCONFIGURED = "Unconfigured"
  CS_STANDALONE = "StandAlone"
  CS_WFCONNECTION = "WFConnection"
  CS_WFREPORTPARAMS = "WFReportParams"
  CS_CONNECTED = "Connected"
  CS_STARTINGSYNCS = "StartingSyncS"
  CS_STARTINGSYNCT = "StartingSyncT"
  CS_WFBITMAPS = "WFBitMapS"
  CS_WFBITMAPT = "WFBitMapT"
  CS_WFSYNCUUID = "WFSyncUUID"
  CS_SYNCSOURCE = "SyncSource"
  CS_SYNCTARGET = "SyncTarget"
  CS_PAUSEDSYNCS = "PausedSyncS"
  CS_PAUSEDSYNCT = "PausedSyncT"
  CSET_SYNC = frozenset([
    CS_WFREPORTPARAMS,
    CS_STARTINGSYNCS,
    CS_STARTINGSYNCT,
    CS_WFBITMAPS,
    CS_WFBITMAPT,
    CS_WFSYNCUUID,
    CS_SYNCSOURCE,
    CS_SYNCTARGET,
    CS_PAUSEDSYNCS,
    CS_PAUSEDSYNCT,
    ])

  DS_DISKLESS = "Diskless"
  DS_ATTACHING = "Attaching" # transient state
  DS_FAILED = "Failed" # transient state, next: diskless
  DS_NEGOTIATING = "Negotiating" # transient state
  DS_INCONSISTENT = "Inconsistent" # while syncing or after creation
  DS_OUTDATED = "Outdated"
  DS_DUNKNOWN = "DUnknown" # shown for peer disk when not connected
  DS_CONSISTENT = "Consistent"
  DS_UPTODATE = "UpToDate" # normal state

  RO_PRIMARY = "Primary"
  RO_SECONDARY = "Secondary"
  RO_UNKNOWN = "Unknown"

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  def __init__(self, procline):
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    u = self.UNCONF_RE.match(procline)
    if u:
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      self.cstatus = self.CS_UNCONFIGURED
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      self.lrole = self.rrole = self.ldisk = self.rdisk = None
    else:
      m = self.LINE_RE.match(procline)
      if not m:
        raise errors.BlockDeviceError("Can't parse input data '%s'" % procline)
      self.cstatus = m.group(1)
      self.lrole = m.group(2)
      self.rrole = m.group(3)
      self.ldisk = m.group(4)
      self.rdisk = m.group(5)

    # end reading of data from the LINE_RE or UNCONF_RE
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    self.is_standalone = self.cstatus == self.CS_STANDALONE
    self.is_wfconn = self.cstatus == self.CS_WFCONNECTION
    self.is_connected = self.cstatus == self.CS_CONNECTED
    self.is_primary = self.lrole == self.RO_PRIMARY
    self.is_secondary = self.lrole == self.RO_SECONDARY
    self.peer_primary = self.rrole == self.RO_PRIMARY
    self.peer_secondary = self.rrole == self.RO_SECONDARY
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    self.both_primary = self.is_primary and self.peer_primary
    self.both_secondary = self.is_secondary and self.peer_secondary

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    self.is_diskless = self.ldisk == self.DS_DISKLESS
    self.is_disk_uptodate = self.ldisk == self.DS_UPTODATE
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    self.is_in_resync = self.cstatus in self.CSET_SYNC
    self.is_in_use = self.cstatus != self.CS_UNCONFIGURED
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    m = self.SYNC_RE.match(procline)
    if m:
      self.sync_percent = float(m.group(1))
      hours = int(m.group(2))
      minutes = int(m.group(3))
      seconds = int(m.group(4))
      self.est_time = hours * 3600 + minutes * 60 + seconds
    else:
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      # we have (in this if branch) no percent information, but if
      # we're resyncing we need to 'fake' a sync percent information,
      # as this is how cmdlib determines if it makes sense to wait for
      # resyncing or not
      if self.is_in_resync:
        self.sync_percent = 0
      else:
        self.sync_percent = None
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      self.est_time = None


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class BaseDRBD(BlockDev): # pylint: disable-msg=W0223
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  """Base DRBD class.
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  This class contains a few bits of common functionality between the
  0.7 and 8.x versions of DRBD.

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  """
  _VERSION_RE = re.compile(r"^version: (\d+)\.(\d+)\.(\d+)"
                           r" \(api:(\d+)/proto:(\d+)(?:-(\d+))?\)")
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  _DRBD_MAJOR = 147
  _ST_UNCONFIGURED = "Unconfigured"
  _ST_WFCONNECTION = "WFConnection"
  _ST_CONNECTED = "Connected"
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  _STATUS_FILE = "/proc/drbd"

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  @staticmethod
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  def _GetProcData(filename=_STATUS_FILE):
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    """Return data from /proc/drbd.
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    """
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    try:
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      data = utils.ReadFile(filename).splitlines()
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    except EnvironmentError, err:
      if err.errno == errno.ENOENT:
        _ThrowError("The file %s cannot be opened, check if the module"
                    " is loaded (%s)", filename, str(err))
      else:
        _ThrowError("Can't read the DRBD proc file %s: %s", filename, str(err))
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    if not data:
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      _ThrowError("Can't read any data from %s", filename)
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    return data
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  @staticmethod
  def _MassageProcData(data):
    """Transform the output of _GetProdData into a nicer form.
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    @return: a dictionary of minor: joined lines from /proc/drbd
        for that minor
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    """
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    lmatch = re.compile("^ *([0-9]+):.*$")
    results = {}
    old_minor = old_line = None
    for line in data:
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      if not line: # completely empty lines, as can be returned by drbd8.0+
        continue
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      lresult = lmatch.match(line)
      if lresult is not None:
        if old_minor is not None:
          results[old_minor] = old_line
        old_minor = int(lresult.group(1))
        old_line = line
      else:
        if old_minor is not None:
          old_line += " " + line.strip()
    # add last line
    if old_minor is not None:
      results[old_minor] = old_line
    return results
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  @classmethod
  def _GetVersion(cls):
    """Return the DRBD version.
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    This will return a dict with keys:
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      - k_major
      - k_minor
      - k_point
      - api
      - proto
      - proto2 (only on drbd > 8.2.X)
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    """
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    proc_data = cls._GetProcData()
    first_line = proc_data[0].strip()
    version = cls._VERSION_RE.match(first_line)
    if not version:
      raise errors.BlockDeviceError("Can't parse DRBD version from '%s'" %
                                    first_line)
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    values = version.groups()
    retval = {'k_major': int(values[0]),
              'k_minor': int(values[1]),
              'k_point': int(values[2]),
              'api': int(values[3]),
              'proto': int(values[4]),
             }
    if values[5] is not None:
      retval['proto2'] = values[5]
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    return retval

  @staticmethod
  def _DevPath(minor):
    """Return the path to a drbd device for a given minor.
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    """
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    return "/dev/drbd%d" % minor
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  @classmethod
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  def GetUsedDevs(cls):
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    """Compute the list of used DRBD devices.
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    """
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    data = cls._GetProcData()
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    used_devs = {}
    valid_line = re.compile("^ *([0-9]+): cs:([^ ]+).*$")
    for line in data:
      match = valid_line.match(line)
      if not match:
        continue
      minor = int(match.group(1))
      state = match.group(2)
      if state == cls._ST_UNCONFIGURED:
        continue
      used_devs[minor] = state, line
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    return used_devs
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  def _SetFromMinor(self, minor):
    """Set our parameters based on the given minor.
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    This sets our minor variable and our dev_path.
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    """
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    if minor is None:
      self.minor = self.dev_path = None
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      self.attached = False
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    else:
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      self.minor = minor
      self.dev_path = self._DevPath(minor)
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      self.attached = True
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  @staticmethod
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  def _CheckMetaSize(meta_device):
    """Check if the given meta device looks like a valid one.
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    This currently only check the size, which must be around
    128MiB.
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    """
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    result = utils.RunCmd(["blockdev", "--getsize", meta_device])
    if result.failed:
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      _ThrowError("Failed to get device size: %s - %s",
                  result.fail_reason, result.output)
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    try:
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      sectors = int(result.stdout)
    except ValueError:
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      _ThrowError("Invalid output from blockdev: '%s'", result.stdout)
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    bytes = sectors * 512
    if bytes < 128 * 1024 * 1024: # less than 128MiB
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      _ThrowError("Meta device too small (%.2fMib)", (bytes / 1024 / 1024))
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    # the maximum *valid* size of the meta device when living on top
    # of LVM is hard to compute: it depends on the number of stripes
    # and the PE size; e.g. a 2-stripe, 64MB PE will result in a 128MB
    # (normal size), but an eight-stripe 128MB PE will result in a 1GB
    # size meta device; as such, we restrict it to 1GB (a little bit
    # too generous, but making assumptions about PE size is hard)
    if bytes > 1024 * 1024 * 1024:
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      _ThrowError("Meta device too big (%.2fMiB)", (bytes / 1024 / 1024))
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  def Rename(self, new_id):
    """Rename a device.
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    This is not supported for drbd devices.
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    """
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    raise errors.ProgrammerError("Can't rename a drbd device")
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class DRBD8(BaseDRBD):
  """DRBD v8.x block device.

  This implements the local host part of the DRBD device, i.e. it
  doesn't do anything to the supposed peer. If you need a fully
  connected DRBD pair, you need to use this class on both hosts.

  The unique_id for the drbd device is the (local_ip, local_port,
  remote_ip, remote_port) tuple, and it must have two children: the
  data device and the meta_device. The meta device is checked for
  valid size and is zeroed on create.

  """
  _MAX_MINORS = 255
  _PARSE_SHOW = None

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  # timeout constants
  _NET_RECONFIG_TIMEOUT = 60

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  def __init__(self, unique_id, children, size):
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    if children and children.count(None) > 0:
      children = []
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    if len(children) not in (0, 2):
      raise ValueError("Invalid configuration data %s" % str(children))
    if not isinstance(unique_id, (tuple, list)) or len(unique_id) != 6:
      raise ValueError("Invalid configuration data %s" % str(unique_id))
    (self._lhost, self._lport,
     self._rhost, self._rport,
     self._aminor, self._secret) = unique_id
    if children:
      if not _CanReadDevice(children[1].dev_path):
        logging.info("drbd%s: Ignoring unreadable meta device", self._aminor)
        children = []
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    super(DRBD8, self).__init__(unique_id, children, size)
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    self.major = self._DRBD_MAJOR
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    version = self._GetVersion()
    if version['k_major'] != 8 :
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      _ThrowError("Mismatch in DRBD kernel version and requested ganeti"
                  " usage: kernel is %s.%s, ganeti wants 8.x",
                  version['k_major'], version['k_minor'])
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    if (self._lhost is not None and self._lhost == self._rhost and
        self._lport == self._rport):
      raise ValueError("Invalid configuration data, same local/remote %s" %
                       (unique_id,))
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    self.Attach()

  @classmethod
  def _InitMeta(cls, minor, dev_path):
    """Initialize a meta device.

    This will not work if the given minor is in use.

    """
    result = utils.RunCmd(["drbdmeta", "--force", cls._DevPath(minor),
                           "v08", dev_path, "0", "create-md"])
    if result.failed:
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      _ThrowError("Can't initialize meta device: %s", result.output)
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  @classmethod
  def _FindUnusedMinor(cls):
    """Find an unused DRBD device.

    This is specific to 8.x as the minors are allocated dynamically,
    so non-existing numbers up to a max minor count are actually free.

    """
    data = cls._GetProcData()

    unused_line = re.compile("^ *([0-9]+): cs:Unconfigured$")
    used_line = re.compile("^ *([0-9]+): cs:")
    highest = None
    for line in data:
      match = unused_line.match(line)
      if match:
        return int(match.group(1))
      match = used_line.match(line)
      if match:
        minor = int(match.group(1))
        highest = max(highest, minor)
    if highest is None: # there are no minors in use at all
      return 0
    if highest >= cls._MAX_MINORS:
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      logging.error("Error: no free drbd minors!")
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      raise errors.BlockDeviceError("Can't find a free DRBD minor")
    return highest + 1

  @classmethod
  def _GetShowParser(cls):
    """Return a parser for `drbd show` output.

    This will either create or return an already-create parser for the
    output of the command `drbd show`.

    """
    if cls._PARSE_SHOW is not None:
      return cls._PARSE_SHOW

    # pyparsing setup
    lbrace = pyp.Literal("{").suppress()
    rbrace = pyp.Literal("}").suppress()
    semi = pyp.Literal(";").suppress()
    # this also converts the value to an int
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    number = pyp.Word(pyp.nums).setParseAction(lambda s, l, t: int(t[0]))
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    comment = pyp.Literal ("#") + pyp.Optional(pyp.restOfLine)
    defa = pyp.Literal("_is_default").suppress()
    dbl_quote = pyp.Literal('"').suppress()

    keyword = pyp.Word(pyp.alphanums + '-')

    # value types
    value = pyp.Word(pyp.alphanums + '_-/.:')
    quoted = dbl_quote + pyp.CharsNotIn('"') + dbl_quote
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    addr_type = (pyp.Optional(pyp.Literal("ipv4")).suppress() +
                 pyp.Optional(pyp.Literal("ipv6")).suppress())
    addr_port = (addr_type + pyp.Word(pyp.nums + '.') +
                 pyp.Literal(':').suppress() + number)
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    # meta device, extended syntax
    meta_value = ((value ^ quoted) + pyp.Literal('[').suppress() +
                  number + pyp.Word(']').suppress())
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    # device name, extended syntax
    device_value = pyp.Literal("minor").suppress() + number
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    # a statement
    stmt = (~rbrace + keyword + ~lbrace +
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            pyp.Optional(addr_port ^ value ^ quoted ^ meta_value ^
                         device_value) +
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            pyp.Optional(defa) + semi +
            pyp.Optional(pyp.restOfLine).suppress())

    # an entire section
    section_name = pyp.Word(pyp.alphas + '_')
    section = section_name + lbrace + pyp.ZeroOrMore(pyp.Group(stmt)) + rbrace

    bnf = pyp.ZeroOrMore(pyp.Group(section ^ stmt))
    bnf.ignore(comment)

    cls._PARSE_SHOW = bnf

    return bnf

  @classmethod
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  def _GetShowData(cls, minor):
    """Return the `drbdsetup show` data for a minor.
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    """
    result = utils.RunCmd(["drbdsetup", cls._DevPath(minor), "show"])
    if result.failed:
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      logging.error("Can't display the drbd config: %s - %s",
                    result.fail_reason, result.output)
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      return None
    return result.stdout

  @classmethod
  def _GetDevInfo(cls, out):
    """Parse details about a given DRBD minor.

    This return, if available, the local backing device (as a path)
    and the local and remote (ip, port) information from a string
    containing the output of the `drbdsetup show` command as returned
    by _GetShowData.

    """