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Commit 76569da2 authored by Nikos Skalkotos's avatar Nikos Skalkotos
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disklabel.py: Use abc.ABCMeta on the base classes 

Make PartitionTableBase and DisklabelBase classes abstract by using the
ABCMeta metaclass of the abc module
parent 718713c1
Hide whitespace changes
Inline Side-by-side
snf-image-helper/disklabel.py
View file @ 76569da2
......@@ -26,6 +26,7 @@ import sys
import os
import cStringIO
import optparse
import abc
from collections import namedtuple
from collections import OrderedDict
......@@ -45,7 +46,7 @@ class MBR(object):
"""Represents a Master Boot Record."""
class Partition(object):
"""Represents a partition entry in MBR"""
format = "<B3sB3sLL"
fmt = "<B3sB3sLL"
def __init__(self, raw_part):
"""Create a Partition instance"""
......@@ -55,11 +56,11 @@ class MBR(object):
self.end,
self.first_sector,
self.sector_count
) = struct.unpack(self.format, raw_part)
) = struct.unpack(self.fmt, raw_part)
def pack(self):
"""Pack the partition values into a binary string"""
return struct.pack(self.format,
return struct.pack(self.fmt,
self.status,
self.start,
self.type,
......@@ -70,7 +71,7 @@ class MBR(object):
@staticmethod
def size():
"""Returns the size of an MBR partition entry"""
return struct.calcsize(MBR.Partition.format)
return struct.calcsize(MBR.Partition.fmt)
def __str__(self):
return "%02Xh %s %02Xh %s %d %d" % (self.status,
......@@ -117,7 +118,7 @@ class MBR(object):
def __init__(self, block):
"""Create an MBR instance"""
self.format = "<444s2x16s16s16s16s2s"
self.fmt = "<444s2x16s16s16s16s2s"
raw_part = {} # Offset Length Contents
(self.code_area, # 0 440(max. 446) code area
# 440 2(optional) disk signature
......@@ -127,7 +128,7 @@ class MBR(object):
raw_part[2], # 478 16 Partition 2
raw_part[3], # 494 16 Partition 3
self.signature # 510 2 MBR signature
) = struct.unpack(self.format, block)
) = struct.unpack(self.fmt, block)
self.part = {}
for i in range(4):
......@@ -135,11 +136,11 @@ class MBR(object):
def size(self):
"""Return the size of a Master Boot Record."""
return struct.calcsize(self.format)
return struct.calcsize(self.fmt)
def pack(self):
"""Pack an MBR to a binary string."""
return struct.pack(self.format,
return struct.pack(self.fmt,
self.code_area,
self.part[0].pack(),
self.part[1].pack(),
......@@ -235,25 +236,19 @@ class Disk(object):
class DisklabelBase(object):
"""Disklabel base class"""
__metaclass__ = abc.ABCMeta
def __init__(self, device):
"""Create a Disklabel instance"""
pass
@property
def format(self):
"""Fields format string"""
raise NotImplementedError
@property
def field(self):
"""Diskalabel Fields data structure"""
raise NotImplementedError
# Subclasses need to overwrite this
self.field = None
self.ptable = None
@property
def ptable(self):
"""Partition Table data structure"""
raise NotImplementedError
@abc.abstractproperty
def fmt(self):
"""Fields format string for the disklabel fields"""
pass
def pack(self, checksum=None):
"""Return a binary copy of the Disklabel block"""
......@@ -264,7 +259,7 @@ class DisklabelBase(object):
else:
out = self.field
return struct.pack(self.format, * out.values() + [self.ptable.pack()])
return struct.pack(self.fmt, * out.values() + [self.ptable.pack()])
def compute_checksum(self):
"""Compute the checksum of the disklabel"""
......@@ -281,10 +276,6 @@ class DisklabelBase(object):
return checksum
def enlarge(self, new_size):
"""Enlarge the disk and return the last useable sector"""
raise NotImplementedError
def write_to(self, device):
"""Write the disklabel to a device"""
......@@ -292,40 +283,63 @@ class DisklabelBase(object):
device.seek(BLOCKSIZE, os.SEEK_CUR)
device.write(self.pack())
def enlarge_last_partition(self):
"""Enlarge the last partition to consume all the useable space"""
raise NotImplementedError
@abc.abstractmethod
def get_last_partition_id(self):
"""Get the ID of the last partition"""
raise NotImplementedError
pass
@abc.abstractmethod
def __str__(self):
"""Print the Disklabel"""
raise NotImplementedError
pass
class PartitionTableBase(object):
"""Base Class for disklabel partition tables"""
__metaclass__ = abc.ABCMeta
@property
def format(self):
"""Partition table format string"""
raise NotImplementedError
@abc.abstractproperty
def fmt(self):
"""Partition fields format string"""
pass
Partition = namedtuple('Partition', '')
@abc.abstractproperty
def fields(self):
"""The partition fields"""
pass
@abc.abstractmethod
def setpsize(self, i, size):
"""Set size for partition i"""
pass
@abc.abstractmethod
def getpsize(self, i):
"""Get size for partition i"""
pass
@abc.abstractmethod
def setpoffset(self, i, offset):
"""Set offset for partition i"""
pass
@abc.abstractmethod
def getpoffset(self, i):
"""Get offset for partition i"""
pass
def __init__(self, ptable, pnumber):
"""Create a Partition Table instance"""
self.part = []
size = struct.calcsize(self.format)
self.Partition = namedtuple('Partition', self.fields)
self.part = []
size = struct.calcsize(self.fmt)
raw = cStringIO.StringIO(ptable)
try:
for _ in xrange(pnumber):
self.part.append(
self.Partition(*struct.unpack(self.format, raw.read(size)))
self.Partition(*struct.unpack(self.fmt, raw.read(size)))
)
finally:
raw.close()
......@@ -341,7 +355,7 @@ class PartitionTableBase(object):
"""Packs the partition table into a binary string."""
ret = ""
for i in xrange(len(self.part)):
ret += struct.pack(self.format, *self.part[i])
ret += struct.pack(self.fmt, *self.part[i])
return ret + ((364 - len(self.part) * 16) * '\x00')
......@@ -351,16 +365,46 @@ class BSDDisklabel(DisklabelBase):
class PartitionTable(PartitionTableBase):
"""Represents a BSD Partition Table"""
format = "<IIIBBH"
Partition = namedtuple(
'Partition', # Offset Length Contents
['size', # 0 4 Number of sectors in partition
'offset', # 4 4 Starting sector
'fsize', # 8 4 Filesystem basic fragment size
'fstype', # 12 1 Filesystem type
'frag', # 13 1 Filesystem fragments per block
'cpg' # 14 2 Filesystem cylinders per group
])
@property
def fmt(self):
"""Partition fields format string"""
return "<IIIBBH"
@property
def fields(self):
"""The partition fields"""
return [ # Offset Length Contents
'size', # 0 4 Number of sectors in partition
'offset', # 4 4 Starting sector of the partition
'fsize', # 8 4 File system basic fragment size
'fstype', # 12 1 File system type
'frag', # 13 1 File system fragments per block
'cpg' # 14 2 File system cylinders per group
]
def setpsize(self, i, size):
"""Set size for partition i"""
tmp = self.part[i]
self.part[i] = self.Partition(size, tmp.offset, tmp.fsize,
tmp.fstype, tmp.frag, tmp.cpg)
def getpsize(self, i):
"""Get size for partition i"""
return self.part[i].size
def setpoffset(self, i, offset):
"""Set offset for partition i"""
tmp = self.part[i]
self.part[i] = self.Partition(tmp.size, offset, tmp.fsize,
tmp.fstype, tmp.frag, tmp.cpg)
def getpoffset(self, i):
"""Get offset for partition i"""
return self.part[i].offset
@property
def fmt(self):
return "<IHH16s16sIIIIIIHHIHHHHIII20s20sIHHII364s"
def __init__(self, device):
"""Create a BSD DiskLabel instance"""
......@@ -371,7 +415,6 @@ class BSDDisklabel(DisklabelBase):
device.seek(BLOCKSIZE, os.SEEK_CUR)
sector1 = device.read(BLOCKSIZE)
self.format = "<IHH16s16sIIIIIIHHIHHHHIII20s20sIHHII364s"
d_ = OrderedDict() # Off Len Content
(d_["magic"], # 0 4 Magic
d_["dtype"], # 4 2 Drive Type
......@@ -402,12 +445,21 @@ class BSDDisklabel(DisklabelBase):
d_["bbsize"], # 132 4 size of boot area at sn0, bytes
d_["sbsize"], # 136 4 Max size of fs superblock, bytes
ptable_raw # 140 16*16 Partition Table
) = struct.unpack(self.format, sector1)
) = struct.unpack(self.fmt, sector1)
assert d_['magic'] == d_['magic2'] == DISKMAGIC, "Disklabel not valid"
self.ptable = self.PartitionTable(ptable_raw, d_['npartitions'])
self.field = d_
def enlarge(self, new_size):
raise NotImplementedError
def enlarge_last_partition(self):
raise NotImplementedError
def get_last_partition_id(self):
raise NotImplementedError
def __str__(self):
"""Print the Disklabel"""
......@@ -455,17 +507,21 @@ class OpenBSDDisklabel(DisklabelBase):
class PartitionTable(PartitionTableBase):
"""Reprepsents an OpenBSD Partition Table"""
format = "<IIHHBBH"
Partition = namedtuple(
'Partition', # Offset Length Contents
['size', # 0 4 Number of sectors in the partition
'offset', # 4 4 Starting sector
'offseth', # 8 2 Starting sector (high part)
'sizeh', # 10 2 Number of sectors (high part)
'fstype', # 12 1 File system type
'frag', # 13 1 File system Fragments per block
'cpg' # 14 2 File system cylinders per group
])
@property
def fmt(self):
return "<IIHHBBH"
@property
def fields(self):
return [ # Offset Length Contents
'size', # 0 4 Number of sectors in the partition
'offset', # 4 4 Starting sector of the partition
'offseth', # 8 2 Starting sector (high part)
'sizeh', # 10 2 Number of sectors (high part)
'fstype', # 12 1 File system type
'frag', # 13 1 File system fragments per block
'cpg' # 14 2 File system cylinders per group
]
def setpsize(self, i, size):
"""Set size for partition i"""
......@@ -489,6 +545,10 @@ class OpenBSDDisklabel(DisklabelBase):
"""Get offset for partition i"""
return (self.part[i].offseth << 32) + self.part[i].offset
@property
def fmt(self):
return "<IHH16s16sIIIIII8sIHHIII20sHH16sIHHII364s"
def __init__(self, device):
"""Create a DiskLabel instance"""
......@@ -498,7 +558,6 @@ class OpenBSDDisklabel(DisklabelBase):
device.seek(BLOCKSIZE, os.SEEK_CUR)
sector1 = device.read(BLOCKSIZE)
self.format = "<IHH16s16sIIIIII8sIHHIII20sHH16sIHHII364s"
d_ = OrderedDict() # Off Len Content
(d_["magic"], # 0 4 Magic
d_["dtype"], # 4 2 Drive Type
......@@ -528,7 +587,7 @@ class OpenBSDDisklabel(DisklabelBase):
d_["bbsize"], # 132 4 size of boot area at sn0, bytes
d_["sbsize"], # 136 4 Max size of fs superblock, bytes
ptable_raw # 140 16*16 Partition Table
) = struct.unpack(self.format, sector1)
) = struct.unpack(self.fmt, sector1)
assert d_['magic'] == d_['magic2'] == DISKMAGIC, "Disklabel not valid"
self.ptable = self.PartitionTable(ptable_raw, d_['npartitions'])
......
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