core: implement System.Runtime.GetInvocationCounter syscall

pkg/compiler/syscall.go

@@ -29,6 +29,7 @@ var syscalls = map[string]map[string]string{
 		"GetEntryScriptHash":     "System.Runtime.GetEntryScriptHash",
 		"GetExecutingScriptHash": "System.Runtime.GetExecutingScriptHash",
 		"GetNotifications":       "System.Runtime.GetNotifications",
+		"GetInvocationCounter":   "System.Runtime.GetInvocationCounter",
 
 		"GasLeft":      "System.Runtime.GasLeft",
 		"GetTrigger":   "System.Runtime.GetTrigger",

pkg/core/interop/context.go

@@ -30,6 +30,7 @@ type Context struct {
 	DAO           *dao.Cached
 	Notifications []state.NotificationEvent
 	Log           *zap.Logger
+	Invocations   map[util.Uint160]int
 }
 
 // NewContext returns new interop context.
@@ -45,6 +46,7 @@ func NewContext(trigger trigger.Type, bc blockchainer.Blockchainer, d dao.DAO, n
 		DAO:           dao,
 		Notifications: nes,
 		Log:           log,
+		Invocations:   make(map[util.Uint160]int),
 	}
 }
 

pkg/core/interop/runtime/util.go

@@ -49,3 +49,13 @@ func GetNotifications(ic *interop.Context, v *vm.VM) error {
 	v.Estack().PushVal(arr)
 	return nil
 }
+
+// GetInvocationCounter returns how many times current contract was invoked during current tx execution.
+func GetInvocationCounter(ic *interop.Context, v *vm.VM) error {
+	count, ok := ic.Invocations[v.GetCurrentScriptHash()]
+	if !ok {
+		return errors.New("current contract wasn't invoked from others")
+	}
+	v.Estack().PushVal(count)
+	return nil
+}

pkg/core/interop_system.go

@@ -443,6 +443,7 @@ func contractCallExInternal(ic *interop.Context, v *vm.VM, h []byte, method stac
 			return errors.New("disallowed method call")
 		}
 	}
+	ic.Invocations[u]++
 	v.LoadScriptWithHash(cs.Script, u, v.Context().GetCallFlags()&f)
 	v.Estack().PushVal(args)
 	v.Estack().PushVal(method)

pkg/core/interop_system_test.go

@@ -7,6 +7,7 @@ import (
 	"github.com/nspcc-dev/dbft/crypto"
 	"github.com/nspcc-dev/neo-go/pkg/core/interop/runtime"
 	"github.com/nspcc-dev/neo-go/pkg/core/state"
+	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
@@ -244,3 +245,20 @@ func TestRuntimeGetNotifications(t *testing.T) {
 		require.Equal(t, ic.Notifications[1].Item, elem[1])
 	})
 }
+
+func TestRuntimeGetInvocationCounter(t *testing.T) {
+	v, ic, chain := createVM(t)
+	defer chain.Close()
+
+	ic.Invocations[hash.Hash160([]byte{2})] = 42
+
+	t.Run("Zero", func(t *testing.T) {
+		v.LoadScript([]byte{1})
+		require.Error(t, runtime.GetInvocationCounter(ic, v))
+	})
+	t.Run("NonZero", func(t *testing.T) {
+		v.LoadScript([]byte{2})
+		require.NoError(t, runtime.GetInvocationCounter(ic, v))
+		require.EqualValues(t, 42, v.Estack().Pop().BigInt().Int64())
+	})
+}

pkg/core/interops.go

@@ -111,6 +111,7 @@ var systemInterops = []interop.Function{
 	{Name: "System.Runtime.GetCallingScriptHash", Func: engineGetCallingScriptHash, Price: 400},
 	{Name: "System.Runtime.GetEntryScriptHash", Func: engineGetEntryScriptHash, Price: 400},
 	{Name: "System.Runtime.GetExecutingScriptHash", Func: engineGetExecutingScriptHash, Price: 400},
+	{Name: "System.Runtime.GetInvocationCounter", Func: runtime.GetInvocationCounter, Price: 400},
 	{Name: "System.Runtime.GetScriptContainer", Func: engineGetScriptContainer, Price: 250},
 	{Name: "System.Runtime.GetTime", Func: runtimeGetTime, Price: 250,
 		AllowedTriggers: trigger.Application},

pkg/interop/runtime/runtime.go

@@ -68,3 +68,9 @@ func GasLeft() int64 {
 func GetNotifications(h []byte) [][]interface{} {
 	return nil
 }
+
+// GetInvocationCounter returns how many times current contract was invoked during current tx execution.
+// This function uses `System.Runtime.GetInvocationCounter` syscall.
+func GetInvocationCounter() int {
+	return 0
+}