Revision b50c8289 snf-image-helper/disklabel.py
| b/snf-image-helper/disklabel.py | ||
|---|---|---|
| 98 | 98 |
def pack_chs(cylinder, head, sector): |
| 99 | 99 |
"""Packs a CHS tuple to an address string.""" |
| 100 | 100 |
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assert 1 <= sector <= 63 |
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assert 0 <= head <= 255 |
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assert 0 <= cylinder |
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|
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# If the cylinders overflow then put the value (1023, 254, 63) to |
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# the tuple. At least this is what OpenBSD does. |
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if cylinder > 1023: |
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cylinder = 1023 |
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head = 254 |
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sector = 63 |
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assert 1 <= sector < 2**6, "Invalid sector value" |
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assert 0 <= head < 2**8, "Invalid head value" |
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assert 0 <= cylinder < 2**10, "Invalid cylinder value" |
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| 111 | 104 |
|
| 112 | 105 |
byte0 = head |
| 113 | 106 |
byte1 = (cylinder >> 2) & 0xC0 | sector |
| ... | ... | |
| 209 | 202 |
start = self.mbr.part[self.part_num].first_sector |
| 210 | 203 |
self.mbr.part[self.part_num].sector_count = end - start + 1 |
| 211 | 204 |
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ntracks = self.disklabel.field['ntracks'] |
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nsectors = self.disklabel.field['nsectors'] |
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# There are cases where the CHS address changes although the LBA |
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# address remains the same. For example when the bios is configured |
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# to use a disk in LBA-Assisted translation mode, the CHS |
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# representation depends on the size of the disk. When we enlarge the |
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# size of the disk we may have to update the starting sector's CHS |
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# address too. |
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start_chs = MBR.Partition.pack_chs(*self.disklabel.lba2chs(start)) |
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self.mbr.part[self.part_num].start = start_chs |
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| 214 | 213 |
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cylinder = end // (ntracks * nsectors) |
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header = (end // nsectors) % ntracks |
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sector = (end % nsectors) + 1 |
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chs = MBR.Partition.pack_chs(cylinder, header, sector) |
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self.mbr.part[self.part_num].end = chs |
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end_chs = MBR.Partition.pack_chs(*self.disklabel.lba2chs(end)) |
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self.mbr.part[self.part_num].end = end_chs |
|
| 220 | 216 |
|
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def enlarge_last_partition(self): |
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"""Enlarge the last partition to cover up all the free space""" |
| ... | ... | |
| 277 | 273 |
|
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return checksum |
| 279 | 275 |
|
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@abc.abstractmethod |
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def enlarge(self, new_size): |
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"""Enlarge the disk and return the last usable sector""" |
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pass |
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|
|
| 285 | 276 |
def write_to(self, device): |
| 286 | 277 |
"""Write the disklabel to a device""" |
| 287 | 278 |
|
| ... | ... | |
| 289 | 280 |
device.seek(BLOCKSIZE, os.SEEK_CUR) |
| 290 | 281 |
device.write(self.pack()) |
| 291 | 282 |
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def lba2chs(self, lba, hpc=None, spt=None): |
|
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"""Returns the CHS address for a given LBA address""" |
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|
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assert hpc is None or hpc > 0, "Invalid heads per cylinder value" |
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assert spt is None or spt > 0, "Invalid sectors per track value" |
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|
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if hpc is None: |
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hpc = self.field['ntracks'] |
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|
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if spt is None: |
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spt = self.field['nsectors'] |
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|
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# See: |
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# http://en.wikipedia.org/wiki/Logical_Block_Addressing#CHS_conversion |
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# |
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cylinder = lba // (spt * hpc) |
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header = (lba // spt) % hpc |
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sector = (lba % spt) + 1 |
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|
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return (cylinder, header, sector) |
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|
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@abc.abstractmethod |
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def enlarge(self, new_size): |
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"""Enlarge the disk and return the last usable sector""" |
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pass |
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|
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@abc.abstractmethod |
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def enlarge_last_partition(self): |
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"""Enlarge the last partition to consume all the usable space""" |
| ... | ... | |
| 484 | 502 |
|
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@property |
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def fields(self): |
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return [ # Offset Length Contents |
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return [ # Offset Length Contents
|
|
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'size', # 0 4 Number of sectors in the partition |
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'offset', # 4 4 Starting sector of the partition |
| 490 | 508 |
'offseth', # 8 2 Starting sector (high part) |
| ... | ... | |
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|
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self.field['checksum'] = self.compute_checksum() |
| 657 | 675 |
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def lba2chs(self, lba, hpc=None, spt=None): |
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"""Returns the CHS address for a given LBA address""" |
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chs = super(OpenBSDDisklabel, self).lba2chs(lba, hpc, spt) |
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# If the cylinders overflow, then OpenBSD will put the value |
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#(1023, 254, 63) to the tuple. |
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if chs[0] > 1023: |
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return (1023, 254, 63) |
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return chs |
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def __str__(self): |
| 659 | 689 |
"""Print the Disklabel""" |
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