Method computeTxEnv

protocols/cpc/api_tracer.go:651–700

computeTxEnv returns the execution environment of a certain transaction.

(blockHash common.Hash, txIndex int, reexec uint64)

// computeTxEnv returns the execution environment of a certain transaction.
func (api *PrivateDebugAPI) computeTxEnv(blockHash common.Hash, txIndex int, reexec uint64) (core.Message, vm.Context, *state.StateDB, error) {
	// Create the parent state database
	block := api.cpc.blockchain.GetBlockByHash(blockHash)
	if block == nil {
		return nil, vm.Context{}, nil, fmt.Errorf("block %x not found", blockHash)
	}
	parent := api.cpc.blockchain.GetBlock(block.ParentHash(), block.NumberU64()-1)
	if parent == nil {
		return nil, vm.Context{}, nil, fmt.Errorf("parent %x not found", block.ParentHash())
	}
	pubStateDB, err := api.computeStateDB(parent, reexec)
	if err != nil {
		return nil, vm.Context{}, nil, err
	}

	privStateDB, err := api.computeStatePrivDB(parent)
	if err != nil {
		// TODO: log the fatal error
		panic(err)
	}

	// Recompute transactions up to the target index.
	signer := types.MakeSigner(api.config)

	for idx, tx := range block.Transactions() {
		// Assemble the transaction call message and return if the requested offset
		msg, _ := tx.AsMessage(signer)
		context := core.NewEVMContext(msg, block.Header(), api.cpc.blockchain, nil)

		var statedb *state.StateDB
		if tx.IsPrivate() {
			statedb = privStateDB // replace with private database.
		} else {
			statedb = pubStateDB
		}

		if idx == txIndex {
			return msg, context, statedb, nil
		}

		// Not yet the searched for transaction, execute on top of the current state
		vmenv := vm.NewEVM(context, statedb, api.config, vm.Config{})
		if _, _, _, err := core.ApplyMessage(vmenv, msg, new(core.GasPool).AddGas(tx.Gas())); err != nil {
			return nil, vm.Context{}, nil, fmt.Errorf("tx %x failed: %v", tx.Hash(), err)
		}
		// Ensure any modifications are committed to the state
		statedb.Finalise(true)
	}
	return nil, vm.Context{}, nil, fmt.Errorf("tx index %d out of range for block %x", txIndex, blockHash)
}