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// Copyright (C) 2015 The Android Open Source Project
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
// This class is used to abstract a filesystem and iterate the blocks
// associated with the files and filesystem structures.
// For the purposes of the update payload generation, a filesystem is a
// formatted partition composed by fixed-size blocks, since that's the interface
// used in the update payload.
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <memory>
#include <string>
#include <vector>
#include <base/macros.h>
#include <brillo/key_value_store.h>
#include <puffin/utils.h>
#include "update_engine/update_metadata.pb.h"
namespace chromeos_update_engine {
class FilesystemInterface {
// This represents a file or pseudo-file in the filesystem. It can include
// all sort of files, like symlinks, hardlinks, directories and even a file
// entry representing the metadata, free space, journaling data, etc.
struct File {
File() { memset(&file_stat, 0, sizeof(file_stat)); }
// The stat struct for the file. This is invalid (inode 0) for some
// pseudo-files.
struct stat file_stat;
// The absolute path to the file inside the filesystem, for example,
// "/usr/bin/bash". For pseudo-files, like blocks associated to internal
// filesystem tables or free space, the path doesn't start with a /.
std::string name;
// The list of all physical blocks holding the data of this file in
// the same order as the logical data. All the block numbers shall be
// between 0 and GetBlockCount() - 1. The blocks are encoded in extents,
// indicating the starting block, and the number of consecutive blocks.
std::vector<Extent> extents;
// All the deflate locations in the file. These locations are not relative
// to the extents. They are relative to the file system itself.
std::vector<puffin::BitExtent> deflates;
virtual ~FilesystemInterface() = default;
// Returns the size of a block in the filesystem.
virtual size_t GetBlockSize() const = 0;
// Returns the number of blocks in the filesystem.
virtual size_t GetBlockCount() const = 0;
// Stores in |files| the list of files and pseudo-files in the filesystem. See
// FileInterface for details. The paths returned by this method shall not
// be repeated; but the same block could be present in more than one file as
// happens for example with hard-linked files, but not limited to those cases.
// Returns whether the function succeeded.
virtual bool GetFiles(std::vector<File>* files) const = 0;
// Load the image settings stored in the filesystem in the
// /etc/update_engine.conf file. Returns whether the settings were found.
virtual bool LoadSettings(brillo::KeyValueStore* store) const = 0;
FilesystemInterface() = default;
} // namespace chromeos_update_engine