blob: 6004443df6aab3bee953e7956169a2758c6edfc5 [file] [log] [blame]
// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef SRC_STORAGE_MINFS_MINFS_INSPECTOR_H_
#define SRC_STORAGE_MINFS_MINFS_INSPECTOR_H_
#include <string>
#include <vector>
#include <disk_inspector/buffer_factory.h>
#include <disk_inspector/common_types.h>
#include <disk_inspector/inspector_transaction_handler.h>
#include "src/lib/storage/block_client/cpp/block_device.h"
#include "src/lib/storage/vfs/cpp/journal/format.h"
#include "src/storage/minfs/format.h"
namespace minfs {
// Bare-bone minfs inspector that loads metadata from the backing block
// device and provides functions to return parsed structs.
// TODO(fxbug.dev/47359): Since this can run on corrupt data, more thought needs
// to be put on the potential edge cases that can happen during corruption.
// Care needs to be put into what dependencies are used when exposing new
// information from this class.
class MinfsInspector {
public:
// Creates a MinfsInspector from a block device. Tries to load the
// superblock from disk upon creation by calling ReloadSuperblock().
static fpromise::result<std::unique_ptr<MinfsInspector>, zx_status_t> Create(
std::unique_ptr<fs::TransactionHandler> handler,
std::unique_ptr<disk_inspector::BufferFactory> factory);
// This function is used to initialize minfs metadata buffers and to load the relavent data.
zx_status_t Initialize();
// Initializes the |superblock_| buffer and tries to load the superblock
// from disk into the buffer. The MinfsInspector should be considered invalid
// and should not be used if this function fails as either VmoBuffers cannot
// be created or we cannot read even the first block from the underlying
// block device.
zx_status_t ReloadSuperblock();
// Initializes the |inode_bitmap_|, |inode_table_|, and |journal_| buffers
// based on |superblock_| and tries to load the associated structs from disk
// into these buffers. Note: we do not consider the failure of initializing
// and loading of any of these buffers to be errors to crash the program as
// the class should still work to a reasonable degree in the case of debugging
// a superblock with corruptions. For cases of failure, these bufffers have
// undefined size and data inside. It is up to users to make sure that they
// make valid calls using other functions in this class.
void ReloadMetadataFromSuperblock();
// Returns a copy of |superblock_|.
Superblock InspectSuperblock();
// Returns the number of inodes from |superblock_|.
uint64_t GetInodeCount();
// Returns the number of journal entires calculated from |superblock_|.
uint64_t GetJournalEntryCount();
// The following functions need to load data from disk, leading to the
// possibility of failed loads. Since they need to return values, we have
// fpromise::results for all of the return types. In addition, they all depend
// on the loaded |superblock_| value to get where to start indexing.
// Loads the inode table blocks for which the inodes from |start_index| inclusive
// to |end_index| exclusive from disk and returns the Inodes in the range as
// a vector.
fpromise::result<std::vector<Inode>, zx_status_t> InspectInodeRange(uint64_t start_index,
uint64_t end_index);
// Loads the inode bitmap blocks for which the inode allocation bits for inodes
// from |start_index| inclusive to |end_index| exclusive from disk and returns
// the inode indices for which the corresponding bits are allocated.
fpromise::result<std::vector<uint64_t>, zx_status_t> InspectInodeAllocatedInRange(
uint64_t start_index, uint64_t end_index);
// Loads the first journal block
fpromise::result<fs::JournalInfo, zx_status_t> InspectJournalSuperblock();
// Loads the |index| element journal entry block and returns it as a struct
// of type T. Only supports casting to fs::JournalPrefix, fs::JournalHeaderBlock,
// and fs::JournalCommitBlock.
template <typename T>
fpromise::result<T, zx_status_t> InspectJournalEntryAs(uint64_t index);
// Loads and returns the backup superblock.
fpromise::result<Superblock, zx_status_t> InspectBackupSuperblock();
// Writes the |superblock| argument to disk and sets |superblock_| to |superblock|
// if the write succeeds.
fpromise::result<void, zx_status_t> WriteSuperblock(Superblock superblock);
private:
explicit MinfsInspector(std::unique_ptr<fs::TransactionHandler> handler,
std::unique_ptr<disk_inspector::BufferFactory> buffer_factory);
zx_status_t LoadJournalEntry(storage::BlockBuffer* buffer, uint64_t index);
std::unique_ptr<fs::TransactionHandler> handler_;
std::unique_ptr<disk_inspector::BufferFactory> buffer_factory_;
Superblock superblock_;
// Scratch buffer initialized to be a single block in the Create method.
// Functions that use this buffer should try to treat it as an initialized
// buffer only valid for the duration of the function without any presaved
// state or ability for the function to save state.
std::unique_ptr<storage::BlockBuffer> buffer_;
};
} // namespace minfs
#endif // SRC_STORAGE_MINFS_MINFS_INSPECTOR_H_