Building a wallet payment

1501
1502    // Set the user desired locktime
1503    coinControl.m_locktime = tx.nLockTime;
1504
1505    // Set the user desired version
1506    coinControl.m_version = tx.version;
1507
1508    // Acquire the locks to prevent races to the new locked unspents between the
1509    // CreateTransaction call and LockCoin calls (when lockUnspents is true).
1510    LOCK(wallet.cs_wallet);
1511
1512    // Fetch specified UTXOs from the UTXO set to get the scriptPubKeys and values of the outputs being selected
1513    // and to match with the given solving_data. Only used for non-wallet outputs.
1514    std::map<COutPoint, Coin> coins;
1515    for (const CTxIn& txin : tx.vin) {
1516        coins[txin.prevout]; // Create empty map entry keyed by prevout.
1517    }
1518    wallet.chain().findCoins(coins);
1519
1520    for (const CTxIn& txin : tx.vin) {
1521        const auto& outPoint = txin.prevout;
1522        PreselectedInput& preset_txin = coinControl.Select(outPoint);
1523        if (!wallet.IsMine(outPoint)) {
1524            if (coins[outPoint].out.IsNull()) {
1525                return util::Error{_("Unable to find UTXO for external input")};
1526            }
1527
1528            // The input was not in the wallet, but is in the UTXO set, so select as external
1529            preset_txin.SetTxOut(coins[outPoint].out);
1530        }
1531        preset_txin.SetSequence(txin.nSequence);
1532        preset_txin.SetScriptSig(txin.scriptSig);
1533        preset_txin.SetScriptWitness(txin.scriptWitness);
1534    }
1535
1536    auto res = CreateTransaction(wallet, vecSend, change_pos, coinControl, false);
1537    if (!res) {
1538        return res;
1539    }
1540
1541    if (lockUnspents) {
1542        for (const CTxIn& txin : res->tx->vin) {
1543            wallet.LockCoin(txin.prevout, /*persist=*/false);
1544        }
1545    }
1546
1547    return res;
1548}
1549} // namespace wallet
1550