eth/tracers: change revert reason to return data

eth/tracers/native/call.go

@@ -83,7 +83,7 @@ func (t *callTracer) CaptureEnd(output []byte, gasUsed uint64, _ time.Duration,
 	t.callstack[0].GasUsed = uintToHex(gasUsed)
 	if err != nil {
 		t.callstack[0].Error = err.Error()
-		if err.Error() == "execution reverted" && len(output) > 0 {
+		if err == vm.ErrExecutionReverted && len(output) > 0 {
 			t.callstack[0].Output = bytesToHex(output)
 		}
 	} else {

eth/tracers/native/returndata.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 <http://www.gnu.org/licenses/>.
+
+package native
+
+import (
+	"encoding/json"
+	"math/big"
+	"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/eth/tracers"
+)
+
+func init() {
+	register("returnDataTracer", newReturnDataTracer)
+}
+
+type returnData struct {
+	Error  string `json:"error,omitempty"`
+	Reason string `json:"reason,omitempty"`
+	Output string `json:"output"`
+}
+
+type returnDataTracer struct {
+	env    *vm.EVM
+	data   returnData
+	reason error // Textual reason for the interruption
+}
+
+// newReturnDataTracer returns a native go tracer which reveals
+// the return data of a tx, and implements vm.EVMLogger.
+func newReturnDataTracer(_ *tracers.Context) tracers.Tracer {
+	return &returnDataTracer{}
+}
+
+// CaptureStart implements the EVMLogger interface to initialize the tracing operation.
+func (t *returnDataTracer) 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 *returnDataTracer) CaptureEnd(output []byte, _ uint64, _ time.Duration, err error) {
+	if err == nil {
+		t.data.Output = bytesToHex(output)
+	} else {
+		t.data.Error = err.Error()
+		if err == vm.ErrExecutionReverted && len(output) > 0 {
+			t.data.Output = bytesToHex(output)
+			if len(output) > 4 {
+				unpacked, errUnpack := abi.UnpackRevert(output)
+				if errUnpack == nil {
+					t.data.Reason = unpacked
+				}
+			}
+		}
+	}
+}
+
+// CaptureState implements the EVMLogger interface to trace a single step of VM execution.
+func (t *returnDataTracer) CaptureState(_ uint64, _ vm.OpCode, _, _ uint64, _ *vm.ScopeContext, _ []byte, _ int, _ error) {
+}
+
+// CaptureFault implements the EVMLogger interface to trace an execution fault.
+func (t *returnDataTracer) 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 *returnDataTracer) CaptureEnter(_ vm.OpCode, _ common.Address, _ common.Address, _ []byte, _ uint64, _ *big.Int) {
+}
+
+// CaptureExit is called when EVM exits a scope, even if the scope didn't
+// execute any code.
+func (t *returnDataTracer) CaptureExit(_ []byte, _ uint64, _ error) {}
+
+func (t *returnDataTracer) CaptureTxStart(_ uint64) {}
+
+func (t *returnDataTracer) CaptureTxEnd(_ uint64) {}
+
+// GetResult returns an error message json object.
+func (t *returnDataTracer) GetResult() (json.RawMessage, error) {
+	res, err := json.Marshal(t.data)
+	if err != nil {
+		return nil, err
+	}
+	return res, t.reason
+}
+
+// Stop terminates execution of the tracer at the first opportune moment.
+func (t *returnDataTracer) Stop(err error) {
+	t.reason = err
+	t.env.Cancel()
+}