pygpt: Add 'create' command.
The 'cgpt create' command initialized a new GPT header and need to do
same thing in pygpt.
BUG=chromium:834237
TEST=make test
Change-Id: I963fda9e41c67b00794216add1f1424bc84caaaa
Reviewed-on: https://chromium-review.googlesource.com/1013454
Commit-Ready: Hung-Te Lin <hungte@chromium.org>
Tested-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-by: Youcheng Syu <youcheng@chromium.org>
diff --git a/py/utils/pygpt.py b/py/utils/pygpt.py
index 292286d..59437a9 100755
--- a/py/utils/pygpt.py
+++ b/py/utils/pygpt.py
@@ -265,6 +265,38 @@
header = super(GPT.Header, self).Clone(**dargs)
return super(GPT.Header, header).Clone(CRC32=binascii.crc32(header.blob))
+ @classmethod
+ def Create(cls, size, block_size, pad_blocks=0,
+ part_entries=DEFAULT_PARTITION_ENTRIES):
+ """Creates a header with default values.
+
+ Args:
+ size: integer of expected image size.
+ block_size: integer for size of each block (sector).
+ pad_blocks: number of preserved sectors between header and partitions.
+ part_entries: number of partitions to include in header.
+ """
+ part_entry_size = struct.calcsize(GPT.Partition.FORMAT)
+ parts_lba = cls.DEFAULT_PARTITIONS_LBA + pad_blocks
+ parts_bytes = part_entries * part_entry_size
+ parts_blocks = parts_bytes / block_size
+ if parts_bytes % block_size:
+ parts_blocks += 1
+ # PartitionsCRC32 must be updated later explicitly.
+ return cls.ReadFrom(None).Clone(
+ Signature=cls.SIGNATURES[0],
+ Revision=cls.DEFAULT_REVISION,
+ HeaderSize=struct.calcsize(cls.FORMAT),
+ CurrentLBA=1,
+ BackupLBA=size / block_size - 1,
+ FirstUsableLBA=parts_lba + parts_blocks,
+ LastUsableLBA=size / block_size - parts_blocks - parts_lba,
+ DiskGUID=uuid.uuid4().get_bytes(),
+ PartitionEntriesStartingLBA=parts_lba,
+ PartitionEntriesNumber=part_entries,
+ PartitionEntrySize=part_entry_size,
+ )
+
class PartitionAttributes(object):
"""Wrapper for Partition.Attributes.
@@ -318,6 +350,13 @@
def __str__(self):
return '%s#%s' % (self.image, self.number)
+ @classmethod
+ def Create(cls, block_size, image, number):
+ """Creates a new partition entry with given meta data."""
+ part = cls.ReadFrom(
+ None, image=image, number=number, block_size=block_size)
+ return part
+
def IsUnused(self):
"""Returns if the partition is unused and can be allocated."""
return self.TypeGUID == GPT.TYPE_GUID_UNUSED
@@ -364,6 +403,24 @@
self.block_size = self.DEFAULT_BLOCK_SIZE
@classmethod
+ def Create(cls, image_name, size, block_size, pad_blocks=0):
+ """Creates a new GPT instance from given size and block_size.
+
+ Args:
+ image_name: a string of underlying disk image file name.
+ size: expected size of disk image.
+ block_size: size of each block (sector) in bytes.
+ pad_blocks: number of blocks between header and partitions array.
+ """
+ gpt = cls()
+ gpt.block_size = block_size
+ gpt.header = cls.Header.Create(size, block_size, pad_blocks)
+ gpt.partitions = [
+ cls.Partition.Create(block_size, image_name, i + 1)
+ for i in xrange(gpt.header.PartitionEntriesNumber)]
+ return gpt
+
+ @classmethod
def LoadFromFile(cls, image):
"""Loads a GPT table from give disk image file object.
@@ -603,6 +660,41 @@
del args # Unused.
raise NotImplementedError
+ class Create(SubCommand):
+ """Create or reset GPT headers and tables.
+
+ Create or reset an empty GPT.
+ """
+
+ def DefineArgs(self, parser):
+ parser.add_argument(
+ '-z', '--zero', action='store_true',
+ help='Zero the sectors of the GPT table and entries')
+ parser.add_argument(
+ '-p', '--pad_blocks', type=int, default=0,
+ help=('Size (in blocks) of the disk to pad between the '
+ 'primary GPT header and its entries, default %(default)s'))
+ parser.add_argument(
+ '--block_size', type=int, default=GPT.DEFAULT_BLOCK_SIZE,
+ help='Size of each block (sector) in bytes.')
+ parser.add_argument(
+ 'image_file', type=argparse.FileType('rb+'),
+ help='Disk image file to create.')
+
+ def Execute(self, args):
+ block_size = args.block_size
+ gpt = GPT.Create(
+ args.image_file.name, os.path.getsize(args.image_file.name),
+ block_size, args.pad_blocks)
+ if args.zero:
+ # In theory we only need to clear LBA 1, but to make sure images already
+ # initialized with different block size won't have GPT signature in
+ # different locations, we should zero until first usable LBA.
+ args.image_file.seek(0)
+ args.image_file.write('\0' * block_size * gpt.header.FirstUsableLBA)
+ gpt.WriteToFile(args.image_file)
+ print('OK: Created GPT for %s' % args.image_file.name)
+
class Repair(SubCommand):
"""Repair damaged GPT headers and tables."""