protolib.py revision 10269
112837Sgabeblack@google.com#!/usr/bin/env python 212837Sgabeblack@google.com 312837Sgabeblack@google.com# Copyright (c) 2013 ARM Limited 412837Sgabeblack@google.com# All rights reserved 512837Sgabeblack@google.com# 612837Sgabeblack@google.com# The license below extends only to copyright in the software and shall 712837Sgabeblack@google.com# not be construed as granting a license to any other intellectual 812837Sgabeblack@google.com# property including but not limited to intellectual property relating 912837Sgabeblack@google.com# to a hardware implementation of the functionality of the software 1012837Sgabeblack@google.com# licensed hereunder. You may use the software subject to the license 1112837Sgabeblack@google.com# terms below provided that you ensure that this notice is replicated 1212837Sgabeblack@google.com# unmodified and in its entirety in all distributions of the software, 1312837Sgabeblack@google.com# modified or unmodified, in source code or in binary form. 1412837Sgabeblack@google.com# 1512837Sgabeblack@google.com# Redistribution and use in source and binary forms, with or without 1612837Sgabeblack@google.com# modification, are permitted provided that the following conditions are 1712837Sgabeblack@google.com# met: redistributions of source code must retain the above copyright 1812837Sgabeblack@google.com# notice, this list of conditions and the following disclaimer; 1912837Sgabeblack@google.com# redistributions in binary form must reproduce the above copyright 2012837Sgabeblack@google.com# notice, this list of conditions and the following disclaimer in the 2112837Sgabeblack@google.com# documentation and/or other materials provided with the distribution; 2212837Sgabeblack@google.com# neither the name of the copyright holders nor the names of its 2312837Sgabeblack@google.com# contributors may be used to endorse or promote products derived from 2412837Sgabeblack@google.com# this software without specific prior written permission. 2512837Sgabeblack@google.com# 2612837Sgabeblack@google.com# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 2712837Sgabeblack@google.com# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 2812837Sgabeblack@google.com# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 2912837Sgabeblack@google.com# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 3012948Sgabeblack@google.com# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 3112948Sgabeblack@google.com# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 3212837Sgabeblack@google.com# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 3312837Sgabeblack@google.com# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 3412837Sgabeblack@google.com# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 3512837Sgabeblack@google.com# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 3612837Sgabeblack@google.com# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 3712837Sgabeblack@google.com# 3812948Sgabeblack@google.com# Copyright 2008 Google Inc. All rights reserved. 3912948Sgabeblack@google.com# http://code.google.com/p/protobuf/ 4012948Sgabeblack@google.com# 4112837Sgabeblack@google.com# Redistribution and use in source and binary forms, with or without 4212948Sgabeblack@google.com# modification, are permitted provided that the following conditions are 4312837Sgabeblack@google.com# met: 4412837Sgabeblack@google.com# 4512837Sgabeblack@google.com# * Redistributions of source code must retain the above copyright 4612837Sgabeblack@google.com# notice, this list of conditions and the following disclaimer. 4712948Sgabeblack@google.com# * Redistributions in binary form must reproduce the above 4812837Sgabeblack@google.com# copyright notice, this list of conditions and the following disclaimer 4912837Sgabeblack@google.com# in the documentation and/or other materials provided with the 5012837Sgabeblack@google.com# distribution. 5112837Sgabeblack@google.com# * Neither the name of Google Inc. nor the names of its 5212837Sgabeblack@google.com# contributors may be used to endorse or promote products derived from 5312948Sgabeblack@google.com# this software without specific prior written permission. 5412837Sgabeblack@google.com# 5512837Sgabeblack@google.com# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 5612837Sgabeblack@google.com# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 5712837Sgabeblack@google.com# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 5812837Sgabeblack@google.com# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 5912948Sgabeblack@google.com# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 6012837Sgabeblack@google.com# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 6112837Sgabeblack@google.com# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 6212837Sgabeblack@google.com# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 6312837Sgabeblack@google.com# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 6412837Sgabeblack@google.com# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 6512948Sgabeblack@google.com# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 6612837Sgabeblack@google.com# 6712837Sgabeblack@google.com# Authors: Andreas Hansson 6812948Sgabeblack@google.com# Radhika Jagtap 6912948Sgabeblack@google.com 7012948Sgabeblack@google.com# This file is a library of commonly used functions used when interfacing 7112898Sgabeblack@google.com# with protobuf python messages. For eg, the decode scripts for different 7212898Sgabeblack@google.com# types of proto objects can use the same function to decode a single message 7312948Sgabeblack@google.com 7412898Sgabeblack@google.comimport gzip 7512948Sgabeblack@google.comimport struct 7612948Sgabeblack@google.com 7712948Sgabeblack@google.comdef openFileRd(in_file): 7812948Sgabeblack@google.com """ 7912948Sgabeblack@google.com This opens the file passed as argument for reading using an appropriate 8012898Sgabeblack@google.com function depending on if it is gzipped or not. It returns the file 8112898Sgabeblack@google.com handle. 8212898Sgabeblack@google.com """ 8312898Sgabeblack@google.com try: 8412898Sgabeblack@google.com # First see if this file is gzipped 8512948Sgabeblack@google.com try: 8612948Sgabeblack@google.com # Opening the file works even if it is not a gzip file 8712948Sgabeblack@google.com proto_in = gzip.open(in_file, 'rb') 8812898Sgabeblack@google.com 8912898Sgabeblack@google.com # Force a check of the magic number by seeking in the 9012898Sgabeblack@google.com # file. If we do not do it here the error will occur when 9112898Sgabeblack@google.com # reading the first message. 9212898Sgabeblack@google.com proto_in.seek(1) 9312898Sgabeblack@google.com proto_in.seek(0) 9412948Sgabeblack@google.com except IOError: 9512948Sgabeblack@google.com proto_in = open(in_file, 'rb') 9612948Sgabeblack@google.com except IOError: 9712898Sgabeblack@google.com print "Failed to open ", in_file, " for reading" 9812898Sgabeblack@google.com exit(-1) 9912898Sgabeblack@google.com return proto_in 10012898Sgabeblack@google.com 10112898Sgabeblack@google.comdef DecodeVarint(in_file): 10212898Sgabeblack@google.com """ 10312948Sgabeblack@google.com The decoding of the Varint32 is copied from 10412948Sgabeblack@google.com google.protobuf.internal.decoder and is only repeated here to 10512948Sgabeblack@google.com avoid depending on the internal functions in the library. If the 10612948Sgabeblack@google.com end of file is reached, return (0, 0). 10712948Sgabeblack@google.com """ 10812948Sgabeblack@google.com result = 0 10912948Sgabeblack@google.com shift = 0 11012948Sgabeblack@google.com pos = 0 11112898Sgabeblack@google.com # Use a 32-bit mask 11212898Sgabeblack@google.com mask = 0xffffffff 11312898Sgabeblack@google.com while 1: 11412948Sgabeblack@google.com c = in_file.read(1) 11512948Sgabeblack@google.com if len(c) == 0: 11612948Sgabeblack@google.com return (0, 0) 11712898Sgabeblack@google.com b = struct.unpack('<B', c)[0] 11812837Sgabeblack@google.com result |= ((b & 0x7f) << shift) 119 pos += 1 120 if not (b & 0x80): 121 if result > 0x7fffffffffffffff: 122 result -= (1 << 64) 123 result |= ~mask 124 else: 125 result &= mask 126 return (result, pos) 127 shift += 7 128 if shift >= 64: 129 raise IOError('Too many bytes when decoding varint.') 130 131def decodeMessage(in_file, message): 132 """ 133 Attempt to read a message from the file and decode it. Return 134 False if no message could be read. 135 """ 136 try: 137 size, pos = DecodeVarint(in_file) 138 if size == 0: 139 return False 140 buf = in_file.read(size) 141 message.ParseFromString(buf) 142 return True 143 except IOError: 144 return False 145 146def EncodeVarint(out_file, value): 147 """ 148 The encoding of the Varint32 is copied from 149 google.protobuf.internal.encoder and is only repeated here to 150 avoid depending on the internal functions in the library. 151 """ 152 bits = value & 0x7f 153 value >>= 7 154 while value: 155 out_file.write(struct.pack('<B', 0x80|bits)) 156 bits = value & 0x7f 157 value >>= 7 158 out_file.write(struct.pack('<B', bits)) 159 160def encodeMessage(out_file, message): 161 """ 162 Encoded a message with the length prepended as a 32-bit varint. 163 """ 164 out = message.SerializeToString() 165 EncodeVarint(out_file, len(out)) 166 out_file.write(out) 167