1 // 2 // Copyright (C) 2015 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_GENERATOR_FILESYSTEM_INTERFACE_H_ 18 #define UPDATE_ENGINE_PAYLOAD_GENERATOR_FILESYSTEM_INTERFACE_H_ 19 20 // This class is used to abstract a filesystem and iterate the blocks 21 // associated with the files and filesystem structures. 22 // For the purposes of the update payload generation, a filesystem is a 23 // formatted partition composed by fixed-size blocks, since that's the interface 24 // used in the update payload. 25 26 #include <sys/stat.h> 27 #include <sys/types.h> 28 #include <unistd.h> 29 30 #include <memory> 31 #include <string> 32 #include <vector> 33 34 #include <brillo/key_value_store.h> 35 #include <puffin/utils.h> 36 37 #include "update_engine/lz4diff/lz4diff_format.h" 38 #include "update_engine/lz4diff/lz4diff.h" 39 #include "update_engine/update_metadata.pb.h" 40 41 namespace chromeos_update_engine { 42 43 class FilesystemInterface { 44 public: 45 // This represents a file or pseudo-file in the filesystem. It can include 46 // all sort of files, like symlinks, hardlinks, directories and even a file 47 // entry representing the metadata, free space, journaling data, etc. 48 49 struct File { FileFile50 File() { memset(&file_stat, 0, sizeof(file_stat)); } 51 52 // The stat struct for the file. This is invalid (inode 0) for some 53 // pseudo-files. 54 struct stat file_stat = {}; 55 56 // The absolute path to the file inside the filesystem, for example, 57 // "/usr/bin/bash". For pseudo-files, like blocks associated to internal 58 // filesystem tables or free space, the path doesn't start with a /. 59 std::string name; 60 61 // The list of all physical blocks holding the data of this file in 62 // the same order as the logical data. All the block numbers shall be 63 // between 0 and GetBlockCount() - 1. The blocks are encoded in extents, 64 // indicating the starting block, and the number of consecutive blocks. 65 std::vector<Extent> extents; 66 67 // If true, the file is already compressed on the disk, so we don't need to 68 // parse it again for deflates. For example, image .gz files inside a 69 // compressed SquashFS image. They might have already been compressed by the 70 // mksquashfs, so we can't really parse the file and look for deflate 71 // compressed parts anymore. 72 bool is_compressed = false; 73 74 // All the deflate locations in the file. These locations are not relative 75 // to the extents. They are relative to the file system itself. 76 std::vector<puffin::BitExtent> deflates; 77 78 CompressedFile compressed_file_info; 79 }; 80 81 virtual ~FilesystemInterface() = default; 82 83 // Returns the size of a block in the filesystem. 84 virtual size_t GetBlockSize() const = 0; 85 86 // Returns the number of blocks in the filesystem. 87 virtual size_t GetBlockCount() const = 0; 88 89 // Stores in |files| the list of files and pseudo-files in the filesystem. See 90 // FileInterface for details. The paths returned by this method shall not 91 // be repeated; but the same block could be present in more than one file as 92 // happens for example with hard-linked files, but not limited to those cases. 93 // Returns whether the function succeeded. 94 virtual bool GetFiles(std::vector<File>* files) const = 0; 95 96 // Load the image settings stored in the filesystem in the 97 // /etc/update_engine.conf file. Returns whether the settings were found. 98 virtual bool LoadSettings(brillo::KeyValueStore* store) const = 0; 99 100 protected: 101 FilesystemInterface() = default; 102 103 private: 104 DISALLOW_COPY_AND_ASSIGN(FilesystemInterface); 105 }; 106 107 } // namespace chromeos_update_engine 108 109 #endif // UPDATE_ENGINE_PAYLOAD_GENERATOR_FILESYSTEM_INTERFACE_H_ 110