1 // 2 // Copyright (C) 2009 The Android Open Source Project 3 // 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // 8 // http://www.apache.org/licenses/LICENSE-2.0 9 // 10 // Unless required by applicable law or agreed to in writing, software 11 // distributed under the License is distributed on an "AS IS" BASIS, 12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 // See the License for the specific language governing permissions and 14 // limitations under the License. 15 // 16 17 #ifndef UPDATE_ENGINE_PAYLOAD_CONSUMER_EXTENT_WRITER_H_ 18 #define UPDATE_ENGINE_PAYLOAD_CONSUMER_EXTENT_WRITER_H_ 19 20 #include <memory> 21 #include <utility> 22 23 #include <base/logging.h> 24 #include <brillo/secure_blob.h> 25 26 #include "update_engine/common/utils.h" 27 #include "update_engine/payload_consumer/file_descriptor.h" 28 #include "update_engine/update_metadata.pb.h" 29 30 // ExtentWriter is an abstract class which synchronously writes to a given 31 // file descriptor at the extents given. 32 33 namespace chromeos_update_engine { 34 35 class ExtentWriter { 36 public: 37 ExtentWriter() = default; ~ExtentWriter()38 virtual ~ExtentWriter() { 39 LOG_IF(ERROR, !end_called_) << "End() not called on ExtentWriter."; 40 } 41 42 // Returns true on success. 43 virtual bool Init(FileDescriptorPtr fd, 44 const google::protobuf::RepeatedPtrField<Extent>& extents, 45 uint32_t block_size) = 0; 46 47 // Returns true on success. 48 virtual bool Write(const void* bytes, size_t count) = 0; 49 50 // Should be called when all writing is complete. Returns true on success. 51 // The fd is not closed. Caller is responsible for closing it. End()52 bool End() { 53 end_called_ = true; 54 return EndImpl(); 55 } 56 virtual bool EndImpl() = 0; 57 private: 58 bool end_called_{false}; 59 }; 60 61 // DirectExtentWriter is probably the simplest ExtentWriter implementation. 62 // It writes the data directly into the extents. 63 64 class DirectExtentWriter : public ExtentWriter { 65 public: 66 DirectExtentWriter() = default; 67 ~DirectExtentWriter() override = default; 68 Init(FileDescriptorPtr fd,const google::protobuf::RepeatedPtrField<Extent> & extents,uint32_t block_size)69 bool Init(FileDescriptorPtr fd, 70 const google::protobuf::RepeatedPtrField<Extent>& extents, 71 uint32_t block_size) override { 72 fd_ = fd; 73 block_size_ = block_size; 74 extents_ = extents; 75 cur_extent_ = extents_.begin(); 76 return true; 77 } 78 bool Write(const void* bytes, size_t count) override; EndImpl()79 bool EndImpl() override { return true; } 80 81 private: 82 FileDescriptorPtr fd_{nullptr}; 83 84 size_t block_size_{0}; 85 // Bytes written into |cur_extent_| thus far. 86 uint64_t extent_bytes_written_{0}; 87 google::protobuf::RepeatedPtrField<Extent> extents_; 88 // The next call to write should correspond to |cur_extents_|. 89 google::protobuf::RepeatedPtrField<Extent>::iterator cur_extent_; 90 }; 91 92 // Takes an underlying ExtentWriter to which all operations are delegated. 93 // When End() is called, ZeroPadExtentWriter ensures that the total number 94 // of bytes written is a multiple of block_size_. If not, it writes zeros 95 // to pad as needed. 96 97 class ZeroPadExtentWriter : public ExtentWriter { 98 public: ZeroPadExtentWriter(std::unique_ptr<ExtentWriter> underlying_extent_writer)99 explicit ZeroPadExtentWriter( 100 std::unique_ptr<ExtentWriter> underlying_extent_writer) 101 : underlying_extent_writer_(std::move(underlying_extent_writer)) {} 102 ~ZeroPadExtentWriter() override = default; 103 Init(FileDescriptorPtr fd,const google::protobuf::RepeatedPtrField<Extent> & extents,uint32_t block_size)104 bool Init(FileDescriptorPtr fd, 105 const google::protobuf::RepeatedPtrField<Extent>& extents, 106 uint32_t block_size) override { 107 block_size_ = block_size; 108 return underlying_extent_writer_->Init(fd, extents, block_size); 109 } Write(const void * bytes,size_t count)110 bool Write(const void* bytes, size_t count) override { 111 if (underlying_extent_writer_->Write(bytes, count)) { 112 bytes_written_mod_block_size_ += count; 113 bytes_written_mod_block_size_ %= block_size_; 114 return true; 115 } 116 return false; 117 } EndImpl()118 bool EndImpl() override { 119 if (bytes_written_mod_block_size_) { 120 const size_t write_size = block_size_ - bytes_written_mod_block_size_; 121 brillo::Blob zeros(write_size, 0); 122 TEST_AND_RETURN_FALSE(underlying_extent_writer_->Write(zeros.data(), 123 write_size)); 124 } 125 return underlying_extent_writer_->End(); 126 } 127 128 private: 129 std::unique_ptr<ExtentWriter> underlying_extent_writer_; 130 size_t block_size_{0}; 131 size_t bytes_written_mod_block_size_{0}; 132 }; 133 134 } // namespace chromeos_update_engine 135 136 #endif // UPDATE_ENGINE_PAYLOAD_CONSUMER_EXTENT_WRITER_H_ 137