前面介绍过引入xlog，将日志打印成一个xlog文件，这里就来介绍一下怎么将xlog文件解码成正常的可读日志文件。

对于不加密的xlog进行解码

如果在Android代码里初始化xlog的时候，使用的是不加密的方式，比如这样：

Xlog.open(false, Xlog.LEVEL_DEBUG, Xlog.AppednerModeAsync, "", logPath, "dbxLog", "");

最后一个入参表示pubkey，传空就代表不对日志内容进行加密。

那就可以直接用mars工程里的
decode_mars_nocrypt_log_file.py文件直接转换，但是mars提供的这个python工具是python2的版本。现在多数都是用python3的，如果你愿意在本地配多个python版本，那就配置一个python2，添加一些需要的库，直接执行那个就可以。

如果你不想配置python2，就想用python3执行，也可以手动改一下这个python文件，这是我改完后的：

#!/usr/bin/pythonimport sysimport osimport globimport zlibimport structimport binasciiimport tracebackMAGIC_NO_COMPRESS_START = 0x03MAGIC_NO_COMPRESS_START1 = 0x06MAGIC_NO_COMPRESS_NO_CRYPT_START = 0x08MAGIC_COMPRESS_START = 0x04MAGIC_COMPRESS_START1 = 0x05MAGIC_COMPRESS_START2 = 0x07MAGIC_COMPRESS_NO_CRYPT_START = 0x09MAGIC_END = 0x00lastseq = 0def IsGoodLogBuffer(_buffer, _offset, count):    if _offset == len(_buffer): return (True, '')    magic_start = _buffer[_offset]    if MAGIC_NO_COMPRESS_START == magic_start or MAGIC_COMPRESS_START == magic_start or MAGIC_COMPRESS_START1 == magic_start:        crypt_key_len = 4    elif MAGIC_COMPRESS_START2 == magic_start or MAGIC_NO_COMPRESS_START1 == magic_start or MAGIC_NO_COMPRESS_NO_CRYPT_START == magic_start or MAGIC_COMPRESS_NO_CRYPT_START == magic_start:        crypt_key_len = 64    else:        return (False, '_buffer[%d]:%d != MAGIC_NUM_START' % (_offset, _buffer[_offset]))    headerLen = 1 + 2 + 1 + 1 + 4 + crypt_key_len    if _offset + headerLen + 1 + 1 > len(_buffer): return (        False, 'offset:%d > len(buffer):%d' % (_offset, len(_buffer)))    start = _offset + headerLen - 4 - crypt_key_len    length = struct.unpack_from("I", memoryview(_buffer)[start:start + 4].tobytes())[0]    if _offset + headerLen + length + 1 > len(_buffer):        return (            False,            'log length:%d, end pos %d > len(buffer):%d' % (length, _offset + headerLen + length + 1, len(_buffer)))    if MAGIC_END != _buffer[_offset + headerLen + length]: return (False,                                                                   'log length:%d, buffer[%d]:%d != MAGIC_END' % (                                                                       length, _offset + headerLen + length,                                                                       _buffer[_offset + headerLen + length]))    if (1 >= count):        return (True, '')    else:        return IsGoodLogBuffer(_buffer, _offset + headerLen + length + 1, count - 1)def GetLogStartPos(_buffer, _count):    offset = 0    while True:        if offset >= len(_buffer): break        if MAGIC_NO_COMPRESS_START == _buffer[offset] or MAGIC_NO_COMPRESS_START1 == _buffer[            offset] or MAGIC_COMPRESS_START == _buffer[offset] or MAGIC_COMPRESS_START1 == _buffer[            offset] or MAGIC_COMPRESS_START2 == _buffer[offset] or MAGIC_COMPRESS_NO_CRYPT_START == _buffer[            offset] or MAGIC_NO_COMPRESS_NO_CRYPT_START == _buffer[offset]:            if IsGoodLogBuffer(_buffer, offset, _count)[0]: return offset        offset += 1    return -1def DecodeBuffer(_buffer, _offset, _outbuffer):    if _offset >= len(_buffer): return -1    # if _offset + 1 + 4 + 1 + 1 > len(_buffer): return -1    ret = IsGoodLogBuffer(_buffer, _offset, 1)    if not ret[0]:        fixpos = GetLogStartPos(_buffer[_offset:], 1)        if -1 == fixpos:            return -1        else:            _outbuffer.extend("[F]decode_log_file.py decode error len=%d, result:%s \n" % (fixpos, ret[1]))            _offset += fixpos    magic_start = _buffer[_offset]    if MAGIC_NO_COMPRESS_START == magic_start or MAGIC_COMPRESS_START == magic_start or MAGIC_COMPRESS_START1 == magic_start:        crypt_key_len = 4    elif MAGIC_COMPRESS_START2 == magic_start or MAGIC_NO_COMPRESS_START1 == magic_start or MAGIC_NO_COMPRESS_NO_CRYPT_START == magic_start or MAGIC_COMPRESS_NO_CRYPT_START == magic_start:        crypt_key_len = 64    else:        _outbuffer.extend('in DecodeBuffer _buffer[%d]:%d != MAGIC_NUM_START' % (_offset, magic_start))        return -1    headerLen = 1 + 2 + 1 + 1 + 4 + crypt_key_len    start = _offset + headerLen - 4 - crypt_key_len    length = struct.unpack_from("I", memoryview(_buffer)[start:start + 4])[0]    tmpbuffer = bytearray(length)    seq = struct.unpack_from("H", memoryview(_buffer)[start - 2 - 2: start - 2])[0]    begin_hour = struct.unpack_from("c", memoryview(_buffer)[start - 1 - 1:start - 1])[0]    end_hour = struct.unpack_from("c", memoryview(_buffer)[start - 1:start])[0]    global lastseq    if seq != 0 and seq != 1 and lastseq != 0 and seq != (lastseq + 1):        _outbuffer.extend("[F]decode_log_file.py log seq:%d-%d is missing\n" % (lastseq + 1, seq - 1))    if seq != 0:        lastseq = seq    tmpbuffer[:] = _buffer[_offset + headerLen:_offset + headerLen + length]    try:        decompressor = zlib.decompressobj(-zlib.MAX_WBITS)        if MAGIC_NO_COMPRESS_START1 == _buffer[_offset] or MAGIC_COMPRESS_START2 == _buffer[_offset]:            print("use wrong decode script")        elif MAGIC_COMPRESS_START == _buffer[_offset] or MAGIC_COMPRESS_NO_CRYPT_START == _buffer[_offset]:            tmpbuffer = decompressor.decompress(bytes(tmpbuffer))        elif MAGIC_COMPRESS_START1 == _buffer[_offset]:            decompress_data = bytearray()            while len(tmpbuffer) > 0:                single_log_len = struct.unpack_from("H", memoryview(tmpbuffer)[0:2])[0]                decompress_data.extend(tmpbuffer[2:single_log_len + 2])                tmpbuffer[:] = tmpbuffer[single_log_len + 2:len(tmpbuffer)]            tmpbuffer = decompressor.decompress(str(decompress_data))        else:            pass            # _outbuffer.extend('seq:%d, hour:%d-%d len:%d decompress:%d\n' %(seq, ord(begin_hour), ord(end_hour), length, len(tmpbuffer)))    except Exception as e:        traceback.print_exc()        _outbuffer.extend("[F]decode_log_file.py decompress err, " + str(e) + "\n")        return _offset + headerLen + length + 1    _outbuffer.extend(tmpbuffer)    return _offset + headerLen + length + 1def ParseFile(_file, _outfile):    fp = open(_file, "rb")    _buffer = bytearray(os.path.getsize(_file))    fp.readinto(_buffer)    fp.close()    startpos = GetLogStartPos(_buffer, 2)    if -1 == startpos:        return    outbuffer = bytearray()    while True:        startpos = DecodeBuffer(_buffer, startpos, outbuffer)        if -1 == startpos: break;    if 0 == len(outbuffer): return    fpout = open(_outfile, "wb")    fpout.write(outbuffer)    fpout.close()def main(args):    global lastseq    if 1 == len(args):        if os.path.isdir(args[0]):            filelist = glob.glob(args[0] + "/*.xlog")            for filepath in filelist:                lastseq = 0                ParseFile(filepath, filepath + ".log")        else:            ParseFile(args[0], args[0] + ".log")    elif 2 == len(args):        ParseFile(args[0], args[1])    else:        filelist = glob.glob("*.xlog")        for filepath in filelist:            lastseq = 0            ParseFile(filepath, filepath + ".log")if __name__ == "__main__":    main(sys.argv[1:])

改的思路其实也很简单，用python3执行，哪里报错改哪里，主要是buffer()方法在python3中没有了，换了一个方法。

这个是我修改后文件（
decode_mars_nocrypt_log_file.py）的地址：
https://www.aliyundrive.com/s/CTiyzYJWjVK

解码的具体操作就是直接执行，将xlog文件作为参数传入：

python decode_mars_nocrypt_log_file.py dbxLog_20220514.xlog

对于加密的xlog进行解码

mars已经提供了加密的工具：gen_key.py，直接执行就可以获取一组随机的公钥、私钥：

通过gen_key.py获取的密钥

在Android代码中初始化xlog的时候，将公钥传递给指定参数，输出的日志就会进行加密：

Xlog.open(false, Xlog.LEVEL_DEBUG, Xlog.AppednerModeAsync, "", logPath, "dbxLog", "68f0b7d5c8a792e1ea94cfc5aaad0db0840282e2b8f5a82f369a996f681c6cd1292f2d6d06712eaf735459584819c4fa71b94f2d9bd53837782ea35aef52ef35");

解码解密的工具是这个：
decode_mars_crypt_log_file.py，mars也有提供，不过不能直接使用，需要将里面的密钥需要进行修改：

更新密钥

需要注意mars提供的这个工具，也是需要python2执行。我有修改成python3的，如果有需要可以看一下：

#!/usr/bin/pythonimport sysimport osimport globimport zlibimport structimport binasciiimport pyellipticimport tracebackMAGIC_NO_COMPRESS_START = 0x03MAGIC_NO_COMPRESS_START1 = 0x06MAGIC_NO_COMPRESS_NO_CRYPT_START = 0x08MAGIC_COMPRESS_START = 0x04MAGIC_COMPRESS_START1 = 0x05MAGIC_COMPRESS_START2 = 0x07MAGIC_COMPRESS_NO_CRYPT_START = 0x09MAGIC_END = 0x00lastseq = 0PRIV_KEY = b'babff40958d0346b8c602dff415e082e94ed5872903ed0ea2a3b198cd3e5d454'PUB_KEY = b'68f0b7d5c8a792e1ea94cfc5aaad0db0840282e2b8f5a82f369a996f681c6cd1'b'292f2d6d06712eaf735459584819c4fa71b94f2d9bd53837782ea35aef52ef35'def tea_decipher(v, k):    op = 0xffffffff    v0, v1 = struct.unpack('=LL', v[0:8])    k1, k2, k3, k4 = struct.unpack('=LLLL', k[0:16])    delta = 0x9E3779B9    s = (delta << 4) & op    for i in range(16):        v1 = (v1 - (((v0 << 4) + k3) ^ (v0 + s) ^ ((v0 >> 5) + k4))) & op        v0 = (v0 - (((v1 << 4) + k1) ^ (v1 + s) ^ ((v1 >> 5) + k2))) & op        s = (s - delta) & op    return struct.pack('=LL', v0, v1)def tea_decrypt(v, k):    num = int(len(v) / 8 * 8)    ret = b''    for i in range(0, num, 8):        vi = v[i:i + 8]        if len(vi) != 8:            continue        x = tea_decipher(vi, k)        ret += x    ret += v[num:]    return retdef IsGoodLogBuffer(_buffer, _offset, count):    if _offset == len(_buffer): return (True, '')    magic_start = _buffer[_offset]    if MAGIC_NO_COMPRESS_START == magic_start or MAGIC_COMPRESS_START == magic_start or MAGIC_COMPRESS_START1 == magic_start:        crypt_key_len = 4    elif MAGIC_COMPRESS_START2 == magic_start or MAGIC_NO_COMPRESS_START1 == magic_start or MAGIC_NO_COMPRESS_NO_CRYPT_START == magic_start or MAGIC_COMPRESS_NO_CRYPT_START == magic_start:        crypt_key_len = 64    else:        return False, '_buffer[%d]:%d != MAGIC_NUM_START' % (_offset, _buffer[_offset])    headerLen = 1 + 2 + 1 + 1 + 4 + crypt_key_len    if _offset + headerLen + 1 + 1 > len(_buffer):        return False, 'offset:%d > len(buffer):%d' % (_offset, len(_buffer))    start = _offset + headerLen - 4 - crypt_key_len    length = struct.unpack_from("I", memoryview(_buffer)[start:start + 4])[0]    if _offset + headerLen + length + 1 > len(_buffer):        return False, 'log length:%d, end pos %d > len(buffer):%d' % (            length, _offset + headerLen + length + 1, len(_buffer))    if MAGIC_END != _buffer[_offset + headerLen + length]:        return False, 'log length:%d, buffer[%d]:%d != MAGIC_END' % (            length, _offset + headerLen + length, _buffer[_offset + headerLen + length])    if (1 >= count):        return (True, '')    else:        return IsGoodLogBuffer(_buffer, _offset + headerLen + length + 1, count - 1)def GetLogStartPos(_buffer, _count):    offset = 0    while True:        if offset >= len(_buffer): break        if MAGIC_NO_COMPRESS_START == _buffer[offset] or MAGIC_NO_COMPRESS_START1 == _buffer[            offset] or MAGIC_COMPRESS_START == _buffer[offset] or MAGIC_COMPRESS_START1 == _buffer[            offset] or MAGIC_COMPRESS_START2 == _buffer[offset] or MAGIC_COMPRESS_NO_CRYPT_START == _buffer[            offset] or MAGIC_NO_COMPRESS_NO_CRYPT_START == _buffer[offset]:            if IsGoodLogBuffer(_buffer, offset, _count)[0]: return offset        offset += 1    return -1def DecodeBuffer(_buffer, _offset, _outbuffer):    if _offset >= len(_buffer):        return -1    # if _offset + 1 + 4 + 1 + 1 > len(_buffer): return -1    ret = IsGoodLogBuffer(_buffer, _offset, 1)    if not ret[0]:        fixpos = GetLogStartPos(_buffer[_offset:], 1)        if -1 == fixpos:            return -1        else:            _outbuffer.extend("[F]decode_log_file.py decode error len=%d, result:%s \n" % (fixpos, ret[1]))            _offset += fixpos    magic_start = _buffer[_offset]    if MAGIC_NO_COMPRESS_START == magic_start or MAGIC_COMPRESS_START == magic_start \            or MAGIC_COMPRESS_START1 == magic_start:        crypt_key_len = 4    elif MAGIC_COMPRESS_START2 == magic_start or MAGIC_NO_COMPRESS_START1 == magic_start \            or MAGIC_NO_COMPRESS_NO_CRYPT_START == magic_start or MAGIC_COMPRESS_NO_CRYPT_START == magic_start:        crypt_key_len = 64    else:        _outbuffer.extend('in DecodeBuffer _buffer[%d]:%d != MAGIC_NUM_START' % (_offset, magic_start))        return -1    headerLen = 1 + 2 + 1 + 1 + 4 + crypt_key_len    start = _offset + headerLen - 4 - crypt_key_len    length = struct.unpack_from("I", memoryview(_buffer)[start: start + 4])[0]    tmpbuffer = bytearray(length)    seq = struct.unpack_from("H", memoryview(_buffer)[start - 2 - 2:start - 2])[0]    begin_hour = struct.unpack_from("c", memoryview(_buffer)[start - 1 - 1:start - 1])[0]    end_hour = struct.unpack_from("c", memoryview(_buffer)[start - 1:start])[0]    global lastseq    if seq != 0 and seq != 1 and lastseq != 0 and seq != (lastseq + 1):        _outbuffer.extend("[F]decode_log_file.py log seq:%d-%d is missing\n" % (lastseq + 1, seq - 1))    if seq != 0:        lastseq = seq    tmpbuffer[:] = _buffer[_offset + headerLen:_offset + headerLen + length]    try:        decompressor = zlib.decompressobj(-zlib.MAX_WBITS)        if MAGIC_NO_COMPRESS_START1 == _buffer[_offset]:            pass        elif MAGIC_COMPRESS_START2 == _buffer[_offset]:            svr = pyelliptic.ECC(curve='secp256k1')            client = pyelliptic.ECC(curve='secp256k1')            start = _offset + headerLen - crypt_key_len            client.pubkey_x = memoryview(_buffer)[start:int(start + crypt_key_len / 2)].tobytes()            client.pubkey_y = memoryview(_buffer)[int(start + crypt_key_len / 2):start + crypt_key_len].tobytes()            svr.privkey = binascii.unhexlify(PRIV_KEY)            tea_key = svr.get_ecdh_key(client.get_pubkey())            tmpbuffer = tea_decrypt(tmpbuffer, tea_key)            tmpbuffer = decompressor.decompress(bytes(tmpbuffer))        elif MAGIC_COMPRESS_START == _buffer[_offset] or MAGIC_COMPRESS_NO_CRYPT_START == _buffer[_offset]:            tmpbuffer = decompressor.decompress(bytes(tmpbuffer))        elif MAGIC_COMPRESS_START1 == _buffer[_offset]:            decompress_data = bytearray()            while len(tmpbuffer) > 0:                single_log_len = struct.unpack_from("H", memoryview(tmpbuffer)[0:2])[0]                decompress_data.extend(tmpbuffer[2:single_log_len + 2])                tmpbuffer[:] = tmpbuffer[single_log_len + 2:len(tmpbuffer)]            tmpbuffer = decompressor.decompress(str(decompress_data))        else:            pass            # _outbuffer.extend('seq:%d, hour:%d-%d len:%d decompress:%d\n' %(seq, ord(begin_hour), ord(end_hour), length, len(tmpbuffer)))    except Exception as e:        traceback.print_exc()        _outbuffer.extend("[F]decode_log_file.py decompress err, " + str(e) + "\n")        return _offset + headerLen + length + 1    _outbuffer.extend(tmpbuffer)    return _offset + headerLen + length + 1def ParseFile(_file, _outfile):    fp = open(_file, "rb")    _buffer = bytearray(os.path.getsize(_file))    fp.readinto(_buffer)    fp.close()    startpos = GetLogStartPos(_buffer, 2)    if -1 == startpos:        return    outbuffer = bytearray()    while True:        startpos = DecodeBuffer(_buffer, startpos, outbuffer)        if -1 == startpos:            break    if 0 == len(outbuffer):        return    fpout = open(_outfile, "wb")    fpout.write(outbuffer)    fpout.close()def main(args):    global lastseq    if 1 == len(args):        if os.path.isdir(args[0]):            filelist = glob.glob(args[0] + "/*.xlog")            for filepath in filelist:                lastseq = 0                ParseFile(filepath, filepath + ".log")        else:            ParseFile(args[0], args[0] + ".log")    elif 2 == len(args):        ParseFile(args[0], args[1])    else:        filelist = glob.glob("*.xlog")        for filepath in filelist:            lastseq = 0            ParseFile(filepath, filepath + ".log")if __name__ == "__main__":    main(sys.argv[1:])

这个是我修改后文件（
decode_mars_crypt_log_file.py）的地址：
https://www.aliyundrive.com/s/oUGormRrEBa

使用方式也是一样的：

python decode_mars_crypt_log_file.py dbxLog_20220514.xlog