1  // Copyright (c) 2009-2010 Satoshi Nakamoto
 2  // Copyright (c) 2009-2020 The Bitcoin Core developers
 3  // Distributed under the MIT software license, see the accompanying
 4  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 5  
 6  #ifndef BITCOIN_UNDO_H
 7  #define BITCOIN_UNDO_H
 8  
 9  #include <coins.h>
10  #include <compressor.h>
11  #include <consensus/consensus.h>
12  #include <primitives/transaction.h>
13  #include <serialize.h>
14  
15  /** Formatter for undo information for a CTxIn
16   *
17   *  Contains the prevout's CTxOut being spent, and its metadata as well
18   *  (coinbase or not, height). The serialization contains a dummy value of
19   *  zero. This is compatible with older versions which expect to see
20   *  the transaction version there.
21   */
22  struct TxInUndoFormatter
23  {
24      template<typename Stream>
25      void Ser(Stream &s, const Coin& txout) {
26          ::Serialize(s, VARINT(txout.nHeight * uint32_t{2} + txout.fCoinBase ));
27          if (txout.nHeight > 0) {
28              // Required to maintain compatibility with older undo format.
29              ::Serialize(s, (unsigned char)0);
30          }
31          ::Serialize(s, Using<TxOutCompression>(txout.out));
32      }
33  
34      template<typename Stream>
35      void Unser(Stream &s, Coin& txout) {
36          uint32_t nCode = 0;
37          ::Unserialize(s, VARINT(nCode));
38          txout.nHeight = nCode >> 1;
39          txout.fCoinBase = nCode & 1;
40          if (txout.nHeight > 0) {
41              // Old versions stored the version number for the last spend of
42              // a transaction's outputs. Non-final spends were indicated with
43              // height = 0.
44              unsigned int nVersionDummy;
45              ::Unserialize(s, VARINT(nVersionDummy));
46          }
47          ::Unserialize(s, Using<TxOutCompression>(txout.out));
48      }
49  };
50  
51  /** Undo information for a CTransaction */
52  class CTxUndo
53  {
54  public:
55      // undo information for all txins
56      std::vector<Coin> vprevout;
57  
58      SERIALIZE_METHODS(CTxUndo, obj) { READWRITE(Using<VectorFormatter<TxInUndoFormatter>>(obj.vprevout)); }
59  };
60  
61  /** Undo information for a CBlock */
62  class CBlockUndo
63  {
64  public:
65      std::vector<CTxUndo> vtxundo; // for all but the coinbase
66  
67      SERIALIZE_METHODS(CBlockUndo, obj) { READWRITE(obj.vtxundo); }
68  };
69  
70  #endif // BITCOIN_UNDO_H