Function CheckInputsFromMempoolAndCache

src/validation.cpp:551–583

Used to avoid mempool polluting consensus critical paths if CCoinsViewMempool were somehow broken and returning the wrong scriptPubKeys

// Used to avoid mempool polluting consensus critical paths if CCoinsViewMempool
// were somehow broken and returning the wrong scriptPubKeys
static bool CheckInputsFromMempoolAndCache(const CTransaction& tx, CValidationState& state, const CCoinsViewCache& view, const CTxMemPool& pool,
                 unsigned int flags, bool cacheSigStore, PrecomputedTransactionData& txdata) {
    AssertLockHeld(cs_main);

    // pool.cs should be locked already, but go ahead and re-take the lock here
    // to enforce that mempool doesn't change between when we check the view
    // and when we actually call through to CheckInputs
    LOCK(pool.cs);

    assert(!tx.IsCoinBase());
    for (const CTxIn& txin : tx.vin) {
        const Coin& coin = view.AccessCoin(txin.prevout);

        // At this point we haven't actually checked if the coins are all
        // available (or shouldn't assume we have, since CheckInputs does).
        // So we just return failure if the inputs are not available here,
        // and then only have to check equivalence for available inputs.
        if (coin.IsSpent()) return false;

        const CTransactionRef& txFrom = pool.get(txin.prevout.hash);
        if (txFrom) {
            assert(txFrom->GetHash() == txin.prevout.hash);
            assert(txFrom->vout.size() > txin.prevout.n);
            assert(txFrom->vout[txin.prevout.n] == coin.out);
        } else {
            const Coin& coinFromDisk = pcoinsTip->AccessCoin(txin.prevout);
            assert(!coinFromDisk.IsSpent());
            assert(coinFromDisk.out == coin.out);
        }
    }

    return CheckInputs(tx, state, view, true, flags, cacheSigStore, true, txdata);
}

static bool AcceptToMemoryPoolWorker(const CChainParams& chainparams, CTxMemPool& pool, CValidationState& state, const CTransactionRef& ptx,
                              bool* pfMissingInputs, int64_t nAcceptTime, std::list<CTransactionRef>* plTxnReplaced,