Get the start offset of an ext4 partition in a raw image file

get-ext4-start-offset.py

search_bytes = b'\x53\xef'
with open('system.raw.img.tmp', 'rb') as f:
    i = 0
    while True:
        byte = f.read(1)
        if not byte:
            break
        elif byte == search_bytes[i:i+1]:
            i += 1
        elif byte == search_bytes[0:1]:
            i = 1
        else:
            i = 0
        if i == len(search_bytes):
            print(f.tell() - len(search_bytes) - 1080)
            break