migrate.h raw

   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
 111