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| from pathlib import Path
import re
import subprocess
def calc_last_usable_lba():
DISK_SECTORS = 30535680
BACKUP_GPT_HEADER_LBA = DISK_SECTORS - 1
BACKUP_PARTITION_ENTRIES_START_LBA = BACKUP_GPT_HEADER_LBA - 32
BACKUP_PARTITION_ENTRIES_END_LBA = BACKUP_GPT_HEADER_LBA - 1
LAST_USABLE_LBA = BACKUP_PARTITION_ENTRIES_START_LBA - 1
assert LAST_USABLE_LBA == 30535646
return LAST_USABLE_LBA
LAST_USABLE_LBA = calc_last_usable_lba()
def calc_layout():
boot_start_lba, boot_sectors = 396384, (64*1024*1024) // 512
udisk_start_lba, udisk_end_lba = 11333632, LAST_USABLE_LBA
udisk_sectors = udisk_end_lba - udisk_start_lba + 1
assert udisk_sectors == 19202015
persist_start = udisk_start_lba - 2 * 7
system_start_lba = boot_start_lba + boot_sectors
system_sectors = persist_start - system_start_lba
assert system_sectors == 10806162
return {
22: (boot_start_lba, boot_sectors),
23: (system_start_lba, system_sectors),
24: (persist_start + 2 * 0, 2),
25: (persist_start + 2 * 1, 2),
26: (persist_start + 2 * 2, 2),
27: (persist_start + 2 * 3, 2),
28: (persist_start + 2 * 4, 2),
29: (persist_start + 2 * 5, 2),
30: (persist_start + 2 * 6, 2),
31: (udisk_start_lba, udisk_sectors),
}
TARGET_LAYOUT = calc_layout()
def read_partition(index):
def pick(pattern, text):
match = re.search(pattern, text, re.MULTILINE)
if not match:
raise SystemExit(f"missing field: {pattern}")
return match.group(1)
IMAGE = Path("y927-original-gpt.img")
text = subprocess.check_output(
["sgdisk", "-i", str(index), str(IMAGE)],
stderr=subprocess.DEVNULL,
text=True,
)
first = int(pick(r"^First sector: (\d+)", text))
last = int(pick(r"^Last sector: (\d+)", text))
return {
"start": first,
"size": last - first + 1,
"type": pick(r"^Partition GUID code: ([0-9A-F-]+)", text),
"uuid": pick(r"^Partition unique GUID: ([0-9A-F-]+)", text),
"attrs": pick(r"^Attribute flags: ([0-9A-Fa-f]+)", text),
"name": pick(r"^Partition name: '([^']*)'", text),
}
lines = [
"label: gpt",
"label-id: 98101B32-BBE2-4BF2-A06E-2BB33D000C20",
"unit: sectors",
"first-lba: 34",
f"last-lba: {LAST_USABLE_LBA}",
"table-length: 32",
"sector-size: 512",
"",
]
for index in range(1, 32):
part = read_partition(index)
if index in TARGET_LAYOUT:
part["start"], part["size"] = TARGET_LAYOUT[index]
attrs = ', attrs="GUID:60"' if part["attrs"] == "1000000000000000" else ""
lines.append(
f"start={part['start']}, size={part['size']}, "
f"type={part['type']}, uuid={part['uuid']}, "
f"name=\"{part['name']}\"{attrs}"
)
Path("y927-linuxroot-system-home-udisk.sfdisk").write_text("\n".join(lines) + "\n")
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