rocksdb/env/fs_remap.h

//  Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
//  This source code is licensed under both the GPLv2 (found in the
//  COPYING file in the root directory) and Apache 2.0 License
//  (found in the LICENSE.Apache file in the root directory).

#pragma once


#include <utility>

#include "rocksdb/file_system.h"

namespace ROCKSDB_NAMESPACE {

// An abstract FileSystem wrapper that creates a view of an existing
// FileSystem by remapping names in some way.
//
// This class has not been fully analyzed for providing strong security
// guarantees.
class RemapFileSystem : public FileSystemWrapper {
 public:
  explicit RemapFileSystem(const std::shared_ptr<FileSystem>& base);

 protected:
  // Returns status and mapped-to path in the wrapped filesystem.
  // If it returns non-OK status, the returned path should not be used.
  virtual std::pair<IOStatus, std::string> EncodePath(
      const std::string& path) = 0;

  // Similar to EncodePath() except used in cases in which it is OK for
  // no file or directory on 'path' to already exist, such as if the
  // operation would create one. However, the parent of 'path' is expected
  // to exist for the operation to succeed.
  // Default implementation: call EncodePath
  virtual std::pair<IOStatus, std::string> EncodePathWithNewBasename(
      const std::string& path);

 public:
  // Left abstract:
  // const char* Name() const override { ... }
  static const char* kClassName() { return "RemapFileSystem"; }
  bool IsInstanceOf(const std::string& id) const override {
    if (id == kClassName()) {
      return true;
    } else {
      return FileSystemWrapper::IsInstanceOf(id);
    }
  }

  Status RegisterDbPaths(const std::vector<std::string>& paths) override;

  Status UnregisterDbPaths(const std::vector<std::string>& paths) override;

  IOStatus NewSequentialFile(const std::string& fname,
                             const FileOptions& options,
                             std::unique_ptr<FSSequentialFile>* result,
                             IODebugContext* dbg) override;

  IOStatus NewRandomAccessFile(const std::string& fname,
                               const FileOptions& options,
                               std::unique_ptr<FSRandomAccessFile>* result,
                               IODebugContext* dbg) override;

  IOStatus NewWritableFile(const std::string& fname, const FileOptions& options,
                           std::unique_ptr<FSWritableFile>* result,
                           IODebugContext* dbg) override;

  IOStatus ReuseWritableFile(const std::string& fname,
                             const std::string& old_fname,
                             const FileOptions& options,
                             std::unique_ptr<FSWritableFile>* result,
                             IODebugContext* dbg) override;

  IOStatus NewRandomRWFile(const std::string& fname, const FileOptions& options,
                           std::unique_ptr<FSRandomRWFile>* result,
                           IODebugContext* dbg) override;

  IOStatus NewDirectory(const std::string& dir, const IOOptions& options,
                        std::unique_ptr<FSDirectory>* result,
                        IODebugContext* dbg) override;

  IOStatus FileExists(const std::string& fname, const IOOptions& options,
                      IODebugContext* dbg) override;

  IOStatus GetChildren(const std::string& dir, const IOOptions& options,
                       std::vector<std::string>* result,
                       IODebugContext* dbg) override;

  IOStatus GetChildrenFileAttributes(const std::string& dir,
                                     const IOOptions& options,
                                     std::vector<FileAttributes>* result,
                                     IODebugContext* dbg) override;

  IOStatus DeleteFile(const std::string& fname, const IOOptions& options,
                      IODebugContext* dbg) override;

  IOStatus CreateDir(const std::string& dirname, const IOOptions& options,
                     IODebugContext* dbg) override;

  IOStatus CreateDirIfMissing(const std::string& dirname,
                              const IOOptions& options,
                              IODebugContext* dbg) override;

  IOStatus DeleteDir(const std::string& dirname, const IOOptions& options,
                     IODebugContext* dbg) override;

  IOStatus GetFileSize(const std::string& fname, const IOOptions& options,
                       uint64_t* file_size, IODebugContext* dbg) override;

  IOStatus GetFileModificationTime(const std::string& fname,
                                   const IOOptions& options,
                                   uint64_t* file_mtime,
                                   IODebugContext* dbg) override;

  IOStatus IsDirectory(const std::string& path, const IOOptions& options,
                       bool* is_dir, IODebugContext* dbg) override;

  IOStatus RenameFile(const std::string& src, const std::string& dest,
                      const IOOptions& options, IODebugContext* dbg) override;

  IOStatus LinkFile(const std::string& src, const std::string& dest,
                    const IOOptions& options, IODebugContext* dbg) override;

  IOStatus LockFile(const std::string& fname, const IOOptions& options,
                    FileLock** lock, IODebugContext* dbg) override;

  IOStatus NewLogger(const std::string& fname, const IOOptions& options,
                     std::shared_ptr<Logger>* result,
                     IODebugContext* dbg) override;

  IOStatus GetAbsolutePath(const std::string& db_path, const IOOptions& options,
                           std::string* output_path,
                           IODebugContext* dbg) override;
};

}  // namespace ROCKSDB_NAMESPACE