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 missingn" % (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:%dn %(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 = bbabff40958d0346b8c602dff415e082e94ed5872903ed0ea2a3b198cd3e5d454PUB_KEY = b68f0b7d5c8a792e1ea94cfc5aaad0db0840282e2b8f5a82f369a996f681c6cd1b292f2d6d06712eaf735459584819c4fa71b94f2d9bd53837782ea35aef52ef35def 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 missingn" % (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:%dn %(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
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