core/vm: adds refund as part of the json standard trace (#17910)

This adds the global accumulated refund counter to the standard
json output as a numeric json value. Previously this was not very
interesting since it was not used much, but with the new sstore
gas changes the value is a lot more interesting from a consensus
investigation perspective.

2 files changed, 20 insertions, 7 deletions

diff --git a/eth/tracers/tracer.go b/eth/tracers/tracer.go
index b519236f2..3533a831f 100644
--- a/eth/tracers/tracer.go
+++ b/eth/tracers/tracer.go
@@ -290,11 +290,12 @@ type Tracer struct {
 	contractWrapper *contractWrapper // Wrapper around the contract object
 	dbWrapper       *dbWrapper       // Wrapper around the VM environment
 
-	pcValue    *uint   // Swappable pc value wrapped by a log accessor
-	gasValue   *uint   // Swappable gas value wrapped by a log accessor
-	costValue  *uint   // Swappable cost value wrapped by a log accessor
-	depthValue *uint   // Swappable depth value wrapped by a log accessor
-	errorValue *string // Swappable error value wrapped by a log accessor
+	pcValue     *uint   // Swappable pc value wrapped by a log accessor
+	gasValue    *uint   // Swappable gas value wrapped by a log accessor
+	costValue   *uint   // Swappable cost value wrapped by a log accessor
+	depthValue  *uint   // Swappable depth value wrapped by a log accessor
+	errorValue  *string // Swappable error value wrapped by a log accessor
+	refundValue *uint   // Swappable refund value wrapped by a log accessor
 
 	ctx map[string]interface{} // Transaction context gathered throughout execution
 	err error                  // Error, if one has occurred
@@ -323,6 +324,7 @@ func New(code string) (*Tracer, error) {
 		gasValue:        new(uint),
 		costValue:       new(uint),
 		depthValue:      new(uint),
+		refundValue:     new(uint),
 	}
 	// Set up builtins for this environment
 	tracer.vm.PushGlobalGoFunction("toHex", func(ctx *duktape.Context) int {
@@ -442,6 +444,9 @@ func New(code string) (*Tracer, error) {
 	tracer.vm.PushGoFunction(func(ctx *duktape.Context) int { ctx.PushUint(*tracer.depthValue); return 1 })
 	tracer.vm.PutPropString(logObject, "getDepth")
 
+	tracer.vm.PushGoFunction(func(ctx *duktape.Context) int { ctx.PushUint(*tracer.refundValue); return 1 })
+	tracer.vm.PutPropString(logObject, "getRefund")
+
 	tracer.vm.PushGoFunction(func(ctx *duktape.Context) int {
 		if tracer.errorValue != nil {
 			ctx.PushString(*tracer.errorValue)
@@ -527,6 +532,7 @@ func (jst *Tracer) CaptureState(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost
 		*jst.gasValue = uint(gas)
 		*jst.costValue = uint(cost)
 		*jst.depthValue = uint(depth)
+		*jst.refundValue = uint(env.StateDB.GetRefund())
 
 		jst.errorValue = nil
 		if err != nil {
diff --git a/eth/tracers/tracer_test.go b/eth/tracers/tracer_test.go
index 58b624724..52f29c83f 100644
--- a/eth/tracers/tracer_test.go
+++ b/eth/tracers/tracer_test.go
@@ -25,6 +25,7 @@ import (
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/params"
 )
@@ -43,8 +44,14 @@ func (account) ReturnGas(*big.Int)                                  {}
 func (account) SetCode(common.Hash, []byte)                         {}
 func (account) ForEachStorage(cb func(key, value common.Hash) bool) {}
 
+type dummyStatedb struct {
+	state.StateDB
+}
+
+func (dummyStatedb) GetRefund() uint64 { return 1337 }
+
 func runTrace(tracer *Tracer) (json.RawMessage, error) {
-	env := vm.NewEVM(vm.Context{BlockNumber: big.NewInt(1)}, nil, params.TestChainConfig, vm.Config{Debug: true, Tracer: tracer})
+	env := vm.NewEVM(vm.Context{BlockNumber: big.NewInt(1)}, &dummyStatedb{}, params.TestChainConfig, vm.Config{Debug: true, Tracer: tracer})
 
 	contract := vm.NewContract(account{}, account{}, big.NewInt(0), 10000)
 	contract.Code = []byte{byte(vm.PUSH1), 0x1, byte(vm.PUSH1), 0x1, 0x0}
@@ -126,7 +133,7 @@ func TestHaltBetweenSteps(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	env := vm.NewEVM(vm.Context{BlockNumber: big.NewInt(1)}, nil, params.TestChainConfig, vm.Config{Debug: true, Tracer: tracer})
+	env := vm.NewEVM(vm.Context{BlockNumber: big.NewInt(1)}, &dummyStatedb{}, params.TestChainConfig, vm.Config{Debug: true, Tracer: tracer})
 	contract := vm.NewContract(&account{}, &account{}, big.NewInt(0), 0)
 
 	tracer.CaptureState(env, 0, 0, 0, 0, nil, nil, contract, 0, nil)