13d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler/* 23d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * Copyright (C) 2016 The Android Open Source Project 33d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * 43d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * Licensed under the Apache License, Version 2.0 (the "License"); 53d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * you may not use this file except in compliance with the License. 63d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * You may obtain a copy of the License at 73d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * 83d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * http://www.apache.org/licenses/LICENSE-2.0 93d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * 103d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * Unless required by applicable law or agreed to in writing, software 113d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * distributed under the License is distributed on an "AS IS" BASIS, 123d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 133d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * See the License for the specific language governing permissions and 143d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler * limitations under the License. 153d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler */ 163d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 17a715cb1840f9a0c813c90707a351687f7a77950eMattias Nissler#include <nvram/messages/message_codec.h> 183d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 193d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nisslernamespace nvram { 203d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nisslernamespace proto { 213d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 223d2f13f288feb42f1dfcfe558af27955edefaad3Mattias NisslerMessageEncoderBase::MessageEncoderBase(const void* object, 233d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler const FieldDescriptor* descriptors, 243d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler size_t num_descriptors) 253d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler : object_(object), 263d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler descriptors_(descriptors), 273d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler num_descriptors_(num_descriptors) {} 283d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 293d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nisslerbool MessageEncoderBase::Encode(const void* object, 303d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler ProtoWriter* writer, 313d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler const FieldDescriptor* descriptors, 323d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler size_t num_descriptors) { 333d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler MessageEncoderBase encoder(object, descriptors, num_descriptors); 343d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return encoder.Encode(writer); 353d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler} 363d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 373d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nisslersize_t MessageEncoderBase::GetSize() { 383d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler CountingOutputStreamBuffer counting_stream; 393d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler ProtoWriter writer(&counting_stream); 403d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return EncodeData(&writer) ? counting_stream.bytes_written() : 0; 413d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler} 423d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 433d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nisslerbool MessageEncoderBase::Encode(ProtoWriter* writer) { 443d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // We need to compute the total size of all struct fields up front in order to 453d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // write a length delimiter that designates the end of the encoded nested 463d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // message. Note that computing the size of |object| requires a second 473d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // |EncodeData()| call in addition to the one that actually encodes the data. 483d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // When handling nested message structures, each level triggers its own size 493d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // computation, which are redundant with those performed by the levels above. 503d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // 513d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // For now, we just accept this inefficiency in the interest of keeping things 523d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // simple and correct. If this ever becomes a performance problem for deeply 533d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // nested structs here are some options: 543d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // * Reserve bytes in |writer| for the encoded size. Once |Encode()| 553d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // completes, it is known how many bytes were required, at which point the 563d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // size field can be updated. The drawback with this solution is that 573d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // varint encoding is variable length, so we'd have to write a degenerated 583d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // varint that may occupy more bytes than actually required. 593d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // * Cache encoded sizes in the struct. This is the solution implemented in 603d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // the regular protobuf implementation. This is relatively straightforward, 613d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // but at the expense of holding data in struct that doesn't really belong 623d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // there. 633d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // * Make a first pass over the struct tree, compute sizes and cache them in 643d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // some auxiliary data structure held in the encoder. This is probably the 653d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // cleanest solution, but comes at the expense of having to thread the size 663d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // cache data structure through the encoding logic. 673d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return writer->WriteLengthHeader(GetSize()) && EncodeData(writer); 683d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler} 693d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 703d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nisslerbool MessageEncoderBase::EncodeData(ProtoWriter* writer) { 713d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler for (size_t i = 0; i < num_descriptors_; ++i) { 723d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler const FieldDescriptor& desc = descriptors_[i]; 733d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler writer->set_field_number(desc.field_number); 743d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler if (!desc.encode_function(object_, writer)) { 753d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return false; 763d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler } 773d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler } 783d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 793d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return true; 803d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler} 813d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 823d2f13f288feb42f1dfcfe558af27955edefaad3Mattias NisslerMessageDecoderBase::MessageDecoderBase(void* object, 833d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler const FieldDescriptor* descriptors, 843d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler size_t num_descriptors) 853d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler : object_(object), 863d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler descriptors_(descriptors), 873d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler num_descriptors_(num_descriptors) {} 883d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 893d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nisslerbool MessageDecoderBase::Decode(void* object, 903d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler ProtoReader* reader, 913d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler const FieldDescriptor* descriptors, 923d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler size_t num_descriptors) { 933d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler MessageDecoderBase decoder(object, descriptors, num_descriptors); 943d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return decoder.Decode(reader); 953d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler} 963d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 973d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nisslerbool MessageDecoderBase::Decode(ProtoReader* reader) { 983d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler NestedInputStreamBuffer nested_stream_buffer(reader->stream_buffer(), 993d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler reader->field_size()); 1003d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler ProtoReader nested_reader(&nested_stream_buffer); 1013d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return DecodeData(&nested_reader) && nested_reader.Done(); 1023d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler} 1033d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 1043d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nisslerbool MessageDecoderBase::DecodeData(ProtoReader* reader) { 1053d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler while (!reader->Done()) { 1063d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler if (!reader->ReadWireTag()) { 1073d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return false; 1083d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler } 1093d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler const FieldDescriptor* desc = FindDescriptor(reader); 1103d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler if (desc) { 1113d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler if (!desc->decode_function(object_, reader)) { 1123d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return false; 1133d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler } 1143d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler } else { 1153d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler // Unknown field number or wire type mismatch. Skip field data. 1163d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler if (!reader->SkipField()) { 1173d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return false; 1183d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler } 1193d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler } 1203d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler } 1213d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 1223d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return true; 1233d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler} 1243d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 1253d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nisslerconst FieldDescriptor* MessageDecoderBase::FindDescriptor( 1263d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler ProtoReader* reader) const { 1273d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler for (size_t i = 0; i < num_descriptors_; ++i) { 1283d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler const FieldDescriptor& desc = descriptors_[i]; 1293d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler if (reader->field_number() == desc.field_number && 1303d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler reader->wire_type() == desc.wire_type) { 1313d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return &desc; 1323d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler } 1333d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler } 1343d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler return nullptr; 1353d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler} 1363d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler 1373d2f13f288feb42f1dfcfe558af27955edefaad3Mattias Nissler} // namespace proto 138e52a7f4addee2c1b6b85fbd445890ccc1c5fc2d1Rahul Chaudhry} // namespace nvram 139