55 lines
1.7 KiB
Bash
55 lines
1.7 KiB
Bash
python3 -c "
|
|
CHUNK = 128*512
|
|
LV_START = 5120000*512
|
|
VIRT_SIZE = 9372172288*512
|
|
|
|
def read_virt(offset, length):
|
|
result = bytearray(length)
|
|
pos = offset
|
|
remaining = length
|
|
with open('/dev/md0','rb') as f:
|
|
while remaining > 0:
|
|
group = pos // (5*CHUNK)
|
|
in_group = pos % (5*CHUNK)
|
|
chunk_idx = in_group // CHUNK
|
|
intra = in_group % CHUNK
|
|
seg_len = min(CHUNK-intra, remaining)
|
|
dst_off = pos - offset
|
|
if chunk_idx != 4:
|
|
phys = LV_START + group*4*CHUNK + chunk_idx*CHUNK + intra
|
|
f.seek(phys)
|
|
data = f.read(seg_len)
|
|
result[dst_off:dst_off+len(data)] = data
|
|
pos += seg_len
|
|
remaining -= seg_len
|
|
return bytes(result)
|
|
|
|
# Check last 8MB of virtual disk
|
|
last_8mb_start = VIRT_SIZE - 8*1024*1024
|
|
print(f'Checking last 8MB: virtual bytes {last_8mb_start} to {VIRT_SIZE}')
|
|
print(f'= virtual sectors {last_8mb_start//512} to {VIRT_SIZE//512}')
|
|
|
|
data = read_virt(last_8mb_start, 8*1024*1024)
|
|
nonzero = sum(1 for b in data if b != 0)
|
|
zero_runs = 0
|
|
in_zero = False
|
|
for b in data:
|
|
if b == 0 and not in_zero:
|
|
in_zero = True
|
|
zero_runs += 1
|
|
elif b != 0:
|
|
in_zero = False
|
|
|
|
print(f'Non-zero bytes: {nonzero} / {8*1024*1024}')
|
|
print(f'Zero runs: {zero_runs}')
|
|
print(f'First 32 bytes: {data[:32].hex()}')
|
|
print(f'Last 32 bytes: {data[-32:].hex()}')
|
|
|
|
# Find first non-zero from the end
|
|
for i in range(len(data)-1, -1, -1):
|
|
if data[i] != 0:
|
|
print(f'Last non-zero byte at offset {i} from last_8mb_start')
|
|
print(f'= virtual byte {last_8mb_start+i}')
|
|
break
|
|
"
|