GZIP Timestamp Grabber

import datetime

with open("dk64.z64","rb") as fh: # Change filename to correspond to the ROM
    file_size = len(fh.read())
    dates = {}
    names = []
    for x in range(file_size):
        fh.seek(x)
        data = int.from_bytes(fh.read(3), "big")
        header = int.from_bytes(fh.read(1), "big")
        if data == 0x1F8B08:
            # GZIP File
            fh.seek(x + 4)
            timestamp = int.from_bytes(fh.read(4), "little")
            if timestamp != 0:
                date_time = datetime.datetime.fromtimestamp(timestamp)
                date = str(date_time).split(" ")[0]
                fh.seek(x + 10)
                if header & 8:
                    filename = ""
                    filename_ended = False
                    while not filename_ended:
                        val = int.from_bytes(fh.read(1), "big")
                        if val == 0:
                            filename_ended = True
                        else:
                            filename += bytearray([val]).decode("ascii")
                            # filename += hex(val)[2:] # JP
                    if filename not in names:
                        names.append(filename)
                if date in dates:
                    dates[date]["count"] += 1
                    dates[date]["files"].append(hex(x))
                else:
                    dates[date] = {
                        "count": 1,
                        "files": [hex(x)]
                    }
    print(dates)
    print(names)