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Diffstat (limited to 'util/protolib.py')
| -rw-r--r-- | util/protolib.py | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/util/protolib.py b/util/protolib.py new file mode 100644 index 000000000..e085a90f2 --- /dev/null +++ b/util/protolib.py @@ -0,0 +1,141 @@ +#!/usr/bin/env python + +# Copyright (c) 2013 ARM Limited +# All rights reserved +# +# The license below extends only to copyright in the software and shall +# not be construed as granting a license to any other intellectual +# property including but not limited to intellectual property relating +# to a hardware implementation of the functionality of the software +# licensed hereunder. You may use the software subject to the license +# terms below provided that you ensure that this notice is replicated +# unmodified and in its entirety in all distributions of the software, +# modified or unmodified, in source code or in binary form. +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions are +# met: redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer; +# redistributions in binary form must reproduce the above copyright +# notice, this list of conditions and the following disclaimer in the +# documentation and/or other materials provided with the distribution; +# neither the name of the copyright holders nor the names of its +# contributors may be used to endorse or promote products derived from +# this software without specific prior written permission. +# +# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +# +# Copyright 2008 Google Inc. All rights reserved. +# http://code.google.com/p/protobuf/ +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions are +# met: +# +# * Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# * Redistributions in binary form must reproduce the above +# copyright notice, this list of conditions and the following disclaimer +# in the documentation and/or other materials provided with the +# distribution. +# * Neither the name of Google Inc. nor the names of its +# contributors may be used to endorse or promote products derived from +# this software without specific prior written permission. +# +# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +# +# Authors: Andreas Hansson +# Radhika Jagtap + +# This file is a library of commonly used functions used when interfacing +# with protobuf python messages. For eg, the decode scripts for different +# types of proto objects can use the same function to decode a single message + +import struct + +def DecodeVarint(in_file): + """ + The decoding of the Varint32 is copied from + google.protobuf.internal.decoder and is only repeated here to + avoid depending on the internal functions in the library. If the + end of file is reached, return (0, 0). + """ + result = 0 + shift = 0 + pos = 0 + # Use a 32-bit mask + mask = 0xffffffff + while 1: + c = in_file.read(1) + if len(c) == 0: + return (0, 0) + b = struct.unpack('<B', c)[0] + result |= ((b & 0x7f) << shift) + pos += 1 + if not (b & 0x80): + if result > 0x7fffffffffffffff: + result -= (1 << 64) + result |= ~mask + else: + result &= mask + return (result, pos) + shift += 7 + if shift >= 64: + raise IOError('Too many bytes when decoding varint.') + +def decodeMessage(in_file, message): + """ + Attempt to read a message from the file and decode it. Return + False if no message could be read. + """ + try: + size, pos = DecodeVarint(in_file) + if size == 0: + return False + buf = in_file.read(size) + message.ParseFromString(buf) + return True + except IOError: + return False + +def EncodeVarint(out_file, value): + """ + The encoding of the Varint32 is copied from + google.protobuf.internal.encoder and is only repeated here to + avoid depending on the internal functions in the library. + """ + bits = value & 0x7f + value >>= 7 + while value: + out_file.write(struct.pack('<B', 0x80|bits)) + bits = value & 0x7f + value >>= 7 + out_file.write(struct.pack('<B', bits)) + +def encodeMessage(out_file, message): + """ + Encoded a message with the length prepended as a 32-bit varint. + """ + out = message.SerializeToString() + EncodeVarint(out_file, len(out)) + out_file.write(out) |