Merge pull request #161 from ElrondNetwork/callback-out-of-gas-fix

Fix panic in async out-of-gas case

arwen/host/asyncCall.go

@@ -293,6 +293,12 @@ func (host *vmHost) processCallbackVMOutput(callbackVMOutput *vmcommon.VMOutput,
 	output := host.Output()
 
 	runtime.GetVMInput().GasProvided = 0
+
+	if callbackVMOutput == nil {
+		callbackVMOutput = output.CreateVMOutputInCaseOfError(callBackErr)
+	}
+
+	output.SetReturnMessage(callbackVMOutput.ReturnMessage)
 	output.Finish([]byte(callbackVMOutput.ReturnCode.String()))
 	output.Finish([]byte(runtime.GetCurrentTxHash()))
 

arwen/host/execution_test.go

@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/ElrondNetwork/arwen-wasm-vm/arwen"
+	"github.com/ElrondNetwork/arwen-wasm-vm/config"
 	"github.com/ElrondNetwork/arwen-wasm-vm/mock"
 	vmcommon "github.com/ElrondNetwork/elrond-vm-common"
 	"github.com/stretchr/testify/assert"
@@ -1091,6 +1092,31 @@ func TestExecution_AsyncCall_BuiltinFails(t *testing.T) {
 	require.Equal(t, [][]byte{[]byte("hello"), {4}}, vmOutput.ReturnData)
 }
 
+func TestExecution_AsyncCall_CallBackFailsBeforeExecution(t *testing.T) {
+	config.AsyncCallbackGasLockForTests = uint64(2)
+
+	code := GetTestSCCode("async-call-builtin", "../../")
+	scBalance := big.NewInt(1000)
+
+	host, stubBlockchainHook := DefaultTestArwenForCall(t, code, scBalance)
+	stubBlockchainHook.ProcessBuiltInFunctionCalled = dummyProcessBuiltInFunction
+	host.protocolBuiltinFunctions = getDummyBuiltinFunctionNames()
+
+	input := DefaultTestContractCallInput()
+	input.RecipientAddr = parentAddress
+	input.Function = "performAsyncCallToBuiltin"
+	input.Arguments = [][]byte{{1}}
+	input.GasProvided = 1000000
+	input.CurrentTxHash = []byte("txhash")
+
+	vmOutput, err := host.RunSmartContractCall(input)
+	require.Nil(t, err)
+
+	require.NotNil(t, vmOutput)
+	require.Equal(t, vmcommon.Ok, vmOutput.ReturnCode)
+	require.Equal(t, [][]byte{[]byte("hello"), []byte("out of gas"), []byte("txhash")}, vmOutput.ReturnData)
+}
+
 func TestExecution_CreateNewContract_Success(t *testing.T) {
 	parentCode := GetTestSCCode("deployer", "../../")
 	childCode := GetTestSCCode("init-correct", "../../")

arwen/host/execution_vmoutputs_test.go

@@ -881,6 +881,8 @@ func expectedVMOutput_AsyncCall_CallBackFails(parentCode []byte, childCode []byt
 	AddFinishData(vmOutput, []byte("user error"))
 	AddFinishData(vmOutput, []byte("txhash"))
 
+	vmOutput.ReturnMessage = "callBack error"
+
 	return vmOutput
 }
 

arwen/host/testInitializer.go

@@ -25,6 +25,8 @@ var userAddress = []byte("userAccount.....................")
 var parentAddress = []byte("parentSC........................")
 var childAddress = []byte("childSC.........................")
 
+var CustomGasSchedule = config.GasScheduleMap(nil)
+
 // GetSCCode retrieves the bytecode of a WASM module from a file
 func GetSCCode(fileName string) []byte {
 	code, err := ioutil.ReadFile(filepath.Clean(fileName))
@@ -101,10 +103,15 @@ func DefaultTestArwenForTwoSCs(t *testing.T, parentCode []byte, childCode []byte
 }
 
 func DefaultTestArwen(tb testing.TB, blockchain vmcommon.BlockchainHook, crypto vmcommon.CryptoHook) (*vmHost, error) {
+	gasSchedule := CustomGasSchedule
+	if gasSchedule == nil {
+		gasSchedule = config.MakeGasMapForTests()
+	}
+
 	host, err := NewArwenVM(blockchain, crypto, &arwen.VMHostParameters{
 		VMType:                   defaultVMType,
 		BlockGasLimit:            uint64(1000),
-		GasSchedule:              config.MakeGasMapForTests(),
+		GasSchedule:              gasSchedule,
 		ProtocolBuiltinFunctions: make(vmcommon.FunctionNames),
 		ElrondProtectedKeyPrefix: []byte("ELROND"),
 	})

config/gasSchedule.go

@@ -8,7 +8,8 @@ import (
 )
 
 const GasValueForTests = 1
-const AsyncCallbackGasLockForTests = 100_000
+
+var AsyncCallbackGasLockForTests = uint64(100_000)
 
 // GasScheduleMap (alias) is the map for gas schedule
 type GasScheduleMap = map[string]map[string]uint64