vm: remove default syscall handler

It's not needed anymore. Close #1075.

pkg/vm/interop.go

@@ -1,66 +0,0 @@
-package vm
-
-import (
-	"errors"
-	"fmt"
-	"sort"
-
-	"github.com/nspcc-dev/neo-go/pkg/core/interop/interopnames"
-	"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
-)
-
-// interopIDFuncPrice adds an ID to the InteropFuncPrice.
-type interopIDFuncPrice struct {
-	ID            uint32
-	Func          func(vm *VM) error
-	Price         int64
-	RequiredFlags callflag.CallFlag
-}
-
-var defaultVMInterops = []interopIDFuncPrice{
-	{ID: interopnames.ToID([]byte(interopnames.SystemRuntimeLog)),
-		Func: runtimeLog, Price: 1 << 15, RequiredFlags: callflag.AllowNotify},
-	{ID: interopnames.ToID([]byte(interopnames.SystemRuntimeNotify)),
-		Func: runtimeNotify, Price: 1 << 15, RequiredFlags: callflag.AllowNotify},
-}
-
-func init() {
-	sort.Slice(defaultVMInterops, func(i, j int) bool { return defaultVMInterops[i].ID < defaultVMInterops[j].ID })
-}
-
-func defaultSyscallHandler(v *VM, id uint32) error {
-	n := sort.Search(len(defaultVMInterops), func(i int) bool {
-		return defaultVMInterops[i].ID >= id
-	})
-	if n >= len(defaultVMInterops) || defaultVMInterops[n].ID != id {
-		return errors.New("syscall not found")
-	}
-	d := defaultVMInterops[n]
-	ctxFlag := v.Context().sc.callFlag
-	if !ctxFlag.Has(d.RequiredFlags) {
-		return fmt.Errorf("missing call flags: %05b vs %05b", ctxFlag, d.RequiredFlags)
-	}
-	return d.Func(v)
-}
-
-// runtimeLog handles the syscall "System.Runtime.Log" for printing and logging stuff.
-func runtimeLog(vm *VM) error {
-	msg := vm.Estack().Pop().String()
-	fmt.Printf("NEO-GO-VM (log) > %s\n", msg)
-	return nil
-}
-
-// runtimeNotify handles the syscall "System.Runtime.Notify" for printing and logging stuff.
-func runtimeNotify(vm *VM) error {
-	name := vm.Estack().Pop().String()
-	item := vm.Estack().Pop()
-	fmt.Printf("NEO-GO-VM (notify) > [%s] %s\n", name, item.Value())
-	return nil
-}
-
-// init sorts the global defaultVMInterops value.
-func init() {
-	sort.Slice(defaultVMInterops, func(i, j int) bool {
-		return defaultVMInterops[i].ID < defaultVMInterops[j].ID
-	})
-}

pkg/vm/vm.go

@@ -108,8 +108,6 @@ func NewWithTrigger(t trigger.Type) *VM {
 	vm := &VM{
 		state:   vmstate.None,
 		trigger: t,
-
-		SyscallHandler: defaultSyscallHandler,
 	}
 
 	initStack(&vm.istack, "invocation", nil)
@@ -1458,6 +1456,9 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 
 	case opcode.SYSCALL:
 		interopID := GetInteropID(parameter)
+		if v.SyscallHandler == nil {
+			panic("vm's SyscallHandler is not initialized")
+		}
 		err := v.SyscallHandler(v, interopID)
 		if err != nil {
 			panic(fmt.Sprintf("failed to invoke syscall %d: %s", interopID, err))

pkg/vm/vm_test.go

@@ -17,6 +17,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
 	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
 	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
@@ -2747,6 +2748,19 @@ func TestRemoveReferrer(t *testing.T) {
 	assert.Equal(t, 0, int(vm.refs))
 }
 
+func TestUninitializedSyscallHandler(t *testing.T) {
+	v := newTestVM()
+	v.Reset(trigger.Application) // Reset SyscallHandler.
+	id := make([]byte, 4)
+	binary.LittleEndian.PutUint32(id, interopnames.ToID([]byte(interopnames.SystemRuntimeGasLeft)))
+	script := append([]byte{byte(opcode.SYSCALL)}, id...)
+	v.LoadScript(script)
+	err := v.Run()
+	require.Error(t, err)
+	require.True(t, strings.Contains(err.Error(), "SyscallHandler is not initialized"), err.Error())
+	assert.Equal(t, true, v.HasFailed())
+}
+
 func makeProgram(opcodes ...opcode.Opcode) []byte {
 	prog := make([]byte, len(opcodes)+1) // RET
 	for i := 0; i < len(opcodes); i++ {