diff --git a/eth/tracers/native/revertreason.go b/eth/tracers/native/revertreason.go new file mode 100644 index 000000000..b402396cb --- /dev/null +++ b/eth/tracers/native/revertreason.go @@ -0,0 +1,108 @@ +// Copyright 2022 The go-ethereum Authors +// This file is part of the go-ethereum library. +// +// The go-ethereum library is free software: you can redistribute it and/or modify +// it under the terms of the GNU Lesser General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// The go-ethereum library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU Lesser General Public License for more details. +// +// You should have received a copy of the GNU Lesser General Public License +// along with the go-ethereum library. If not, see . + +package native + +import ( + "bytes" + "encoding/json" + "math/big" + "sync/atomic" + "time" + + "github.com/ethereum/go-ethereum/accounts/abi" + "github.com/ethereum/go-ethereum/common" + "github.com/ethereum/go-ethereum/core/vm" + "github.com/ethereum/go-ethereum/crypto" + "github.com/ethereum/go-ethereum/eth/tracers" +) + +func init() { + register("revertReasonTracer", newRevertReasonTracer) +} + +var revertSelector = crypto.Keccak256([]byte("Error(string)"))[:4] + +// revertReasonTracer is a go implementation of the Tracer interface which +// track the error message or revert reason return by the contract. +type revertReasonTracer struct { + env *vm.EVM + revertReason string // The revert reason return from the tx, if tx success, empty string return + interrupt uint32 // Atomic flag to signal execution interruption + reason error // Textual reason for the interruption +} + +// newRevertReasonTracer returns a new revert reason tracer. +func newRevertReasonTracer(_ *tracers.Context) tracers.Tracer { + return &revertReasonTracer{} +} + +// CaptureStart implements the EVMLogger interface to initialize the tracing operation. +func (t *revertReasonTracer) CaptureStart(env *vm.EVM, _ common.Address, _ common.Address, _ bool, _ []byte, _ uint64, _ *big.Int) { + t.env = env +} + +// CaptureEnd is called after the call finishes to finalize the tracing. +func (t *revertReasonTracer) CaptureEnd(output []byte, _ uint64, _ time.Duration, err error) { + if err != nil { + if err == vm.ErrExecutionReverted && len(output) > 4 && bytes.Equal(output[:4], revertSelector) { + errMsg, _ := abi.UnpackRevert(output) + t.revertReason = err.Error() + ": " + errMsg + } else { + t.revertReason = err.Error() + } + } +} + +// CaptureState implements the EVMLogger interface to trace a single step of VM execution. +func (t *revertReasonTracer) CaptureState(_ uint64, _ vm.OpCode, _, _ uint64, _ *vm.ScopeContext, _ []byte, _ int, _ error) { +} + +// CaptureFault implements the EVMLogger interface to trace an execution fault. +func (t *revertReasonTracer) CaptureFault(_ uint64, _ vm.OpCode, _, _ uint64, _ *vm.ScopeContext, _ int, _ error) { +} + +// CaptureEnter is called when EVM enters a new scope (via call, create or selfdestruct). +func (t *revertReasonTracer) CaptureEnter(_ vm.OpCode, _ common.Address, _ common.Address, _ []byte, _ uint64, _ *big.Int) { + // Skip if tracing was interrupted + if atomic.LoadUint32(&t.interrupt) > 0 { + t.env.Cancel() + return + } +} + +// CaptureExit is called when EVM exits a scope, even if the scope didn't +// execute any code. +func (t *revertReasonTracer) CaptureExit(_ []byte, _ uint64, _ error) {} + +func (t *revertReasonTracer) CaptureTxStart(_ uint64) {} + +func (t *revertReasonTracer) CaptureTxEnd(_ uint64) {} + +// GetResult returns an error message json object. +func (t *revertReasonTracer) GetResult() (json.RawMessage, error) { + res, err := json.Marshal(t.revertReason) + if err != nil { + return nil, err + } + return res, t.reason +} + +// Stop terminates execution of the tracer at the first opportune moment. +func (t *revertReasonTracer) Stop(err error) { + t.reason = err + atomic.StoreUint32(&t.interrupt, 1) +}