Function GetTransaction

src/main.cpp:1775–1840

Return transaction in tx, and if it was found inside a block, its hash is placed in hashBlock */

/** Return transaction in tx, and if it was found inside a block, its hash is placed in hashBlock */
bool GetTransaction(const uint256& hash, CTransaction& txOut, const Consensus::Params& consensusParams, uint256& hashBlock, bool fAllowSlow)
{
    CBlockIndex* pindexSlow = NULL;

    //LOCK(cs_main);

    CTransactionRef ptx = mempool.get(hash);
    if (ptx)
    {
        txOut = *ptx.get();
        return true;
    }

    if (fTxIndex) {
        CDiskTxPos postx;
        if (pblocktree->ReadTxIndex(hash, postx)) {
            CAutoFile file(OpenBlockFile(postx, true), SER_DISK, CLIENT_VERSION);
            if (file.IsNull())
                return error("%s: OpenBlockFile failed", __func__);
            CBlockHeader header;
            try {
                file >> header;
                fseek(file.Get(), postx.nTxOffset, SEEK_CUR);
                file >> txOut;
            } catch (const std::exception& e) {
                return error("%s: Deserialize or I/O error - %s", __func__, e.what());
            }

            CBlockIndex* pindexPrev = LookupBlockIndex(header.hashPrevBlock);
            int TheHeight = pindexPrev ? pindexPrev->nHeight + 1  : 0;
            hashBlock = header.GetHash(TheHeight);
            if (txOut.GetHash() != hash)
                return error("%s: txid mismatch", __func__);
            return true;
        }

        return false;
    }

    if (fAllowSlow) { // use coin database to locate block that contains transaction, and scan it
        int nHeight = -1;
        {
            const CCoinsViewCache& view = *pcoinsTip;
            const CCoins* coins = view.AccessCoins(hash);
            if (coins)
                nHeight = coins->nHeight;
        }
        if (nHeight > 0)
            pindexSlow = chainActive[nHeight];
    }

    if (pindexSlow) {
        CBlock block;
        if (ReadBlockFromDisk(block, pindexSlow, consensusParams)) {
            for (const CTransaction& tx : block.vtx) {
                if (tx.GetHash() == hash) {
                    txOut = tx;
                    hashBlock = pindexSlow->GetBlockHash();