1  // Copyright (c) 2021-present The Bitcoin Core developers
  2  // Distributed under the MIT software license, see the accompanying
  3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  4  
  5  #ifndef BITCOIN_WALLET_MIGRATE_H
  6  #define BITCOIN_WALLET_MIGRATE_H
  7  
  8  #include <wallet/db.h>
  9  
 10  #include <optional>
 11  
 12  namespace wallet {
 13  
 14  using BerkeleyROData = std::map<SerializeData, SerializeData, std::less<>>;
 15  
 16  /**
 17   * A class representing a BerkeleyDB file from which we can only read records.
 18   * This is used only for migration of legacy to descriptor wallets
 19   */
 20  class BerkeleyRODatabase : public WalletDatabase
 21  {
 22  private:
 23      const fs::path m_filepath;
 24  
 25  public:
 26      /** Create DB handle */
 27      BerkeleyRODatabase(const fs::path& filepath, bool open = true) : WalletDatabase(), m_filepath(filepath)
 28      {
 29          if (open) Open();
 30      }
 31      ~BerkeleyRODatabase() = default;
 32  
 33      BerkeleyROData m_records;
 34  
 35      /** Open the database if it is not already opened. */
 36      void Open() override;
 37  
 38      /** Rewrite the entire database on disk
 39       */
 40      bool Rewrite() override { return false; }
 41  
 42      /** Back up the entire database to a file.
 43       */
 44      bool Backup(const std::string& strDest) const override;
 45  
 46      /** Flush to the database file and close the database.
 47       *  Also close the environment if no other databases are open in it.
 48       */
 49      void Close() override {}
 50  
 51      /** Return path to main database file for logs and error messages. */
 52      std::string Filename() override { return fs::PathToString(m_filepath); }
 53      std::vector<fs::path> Files() override { return {m_filepath}; }
 54  
 55      std::string Format() override { return "bdb_ro"; }
 56  
 57      /** Make a DatabaseBatch connected to this database */
 58      std::unique_ptr<DatabaseBatch> MakeBatch() override;
 59  };
 60  
 61  class BerkeleyROCursor : public DatabaseCursor
 62  {
 63  private:
 64      const BerkeleyRODatabase& m_database;
 65      BerkeleyROData::const_iterator m_cursor;
 66      BerkeleyROData::const_iterator m_cursor_end;
 67  
 68  public:
 69      explicit BerkeleyROCursor(const BerkeleyRODatabase& database, std::span<const std::byte> prefix = {});
 70      ~BerkeleyROCursor() = default;
 71  
 72      Status Next(DataStream& key, DataStream& value) override;
 73  };
 74  
 75  /** RAII class that provides access to a BerkeleyRODatabase */
 76  class BerkeleyROBatch : public DatabaseBatch
 77  {
 78  private:
 79      const BerkeleyRODatabase& m_database;
 80  
 81      bool ReadKey(DataStream&& key, DataStream& value) override;
 82      // WriteKey returns true since various automatic upgrades for older wallets will expect writing to not fail.
 83      // It is okay for this batch type to not actually write anything as those automatic upgrades will occur again after migration.
 84      bool WriteKey(DataStream&& key, DataStream&& value, bool overwrite = true) override { return true; }
 85      bool EraseKey(DataStream&& key) override { return false; }
 86      bool HasKey(DataStream&& key) override;
 87      bool ErasePrefix(std::span<const std::byte> prefix) override { return false; }
 88  
 89  public:
 90      explicit BerkeleyROBatch(const BerkeleyRODatabase& database) : m_database(database) {}
 91      ~BerkeleyROBatch() = default;
 92  
 93      BerkeleyROBatch(const BerkeleyROBatch&) = delete;
 94      BerkeleyROBatch& operator=(const BerkeleyROBatch&) = delete;
 95  
 96      void Close() override {}
 97  
 98      std::unique_ptr<DatabaseCursor> GetNewCursor() override { return std::make_unique<BerkeleyROCursor>(m_database); }
 99      std::unique_ptr<DatabaseCursor> GetNewPrefixCursor(std::span<const std::byte> prefix) override;
100      bool TxnBegin() override { return false; }
101      bool TxnCommit() override { return false; }
102      bool TxnAbort() override { return false; }
103      bool HasActiveTxn() override { return false; }
104  };
105  
106  //! Return object giving access to Berkeley Read Only database at specified path.
107  std::unique_ptr<BerkeleyRODatabase> MakeBerkeleyRODatabase(const fs::path& path, const DatabaseOptions& options, DatabaseStatus& status, bilingual_str& error);
108  } // namespace wallet
109  
110  #endif // BITCOIN_WALLET_MIGRATE_H