bea.py

from struct import unpack as up
import sys, os, hashlib
import zstandard as zstd

dirs, files = None, None

def read_at(fp, off, len):
    fp.seek(off)
    return fp.read(len)

def read_u8(fp, off):
    return up('<B', read_at(fp, off, 1))[0]

def read_u16(fp, off):
    return up('<H', read_at(fp, off, 2))[0]

def read_u32(fp, off):
    return up('<I', read_at(fp, off, 4))[0]

def read_u64(fp, off):
    return up('<Q', read_at(fp, off, 8))[0]

def read_filename(fp, off, l):
    if l == 0:
        return ''
    s = read_at(fp, off, l)
    if '\0' in s:
        s = s[:s.index('\0')]
    return s

def read_from_string_table(fp, off):
    return read_at(fp, off + 2, read_u16(fp, off))

def dump_asset(offset):
    global archive, out_dir
    if read_at(archive, offset, 4) != 'ASST':
        print 'Error: Asset is not an ASST?'
    cmp, algn, cmp_size, size, _, data_ofs, name_ofs = up('<HHIIIQQ', read_at(archive, offset + 0x10, 0x20))
    name = read_from_string_table(archive, name_ofs)
    path = os.path.join(out_dir, name)
    try:
        os.makedirs(os.path.dirname(path))
    except:
        pass
    print 'Dumping %s (%012X-%012X) to %s...' % (name, data_ofs, data_ofs+size, path)
    with open(path, 'wb') as f:
        f.write(zstd.ZstdDecompressor().decompress(read_at(archive, data_ofs, cmp_size)))
    print 'Dumped!'


def main(argc, argv):
    if argc != 3:
        print 'Usage: %s in_file out_dir' % argv[0]
        return
    global archive, dirs_off, files_off, fdata_off
    try:
        archive = open(argv[1], 'rb')
        if read_at(archive, 0, 4) != 'SCNE':
            print 'Error: Invalid archive.'
            return
    except:
        print 'Failed to open %s.' % argv[1]
        return

    global out_dir
    out_dir = argv[2]

    num_files, asset_info_ofs = up('<QQ', read_at(archive, 0x20, 0x10))
    print 'Num Files: %d' % num_files
    for i in xrange(num_files):
        dump_asset(read_u64(archive, asset_info_ofs + 8 * i))
    print 'Done!'


if __name__ == '__main__':
    main(len(sys.argv), sys.argv)