interop: allow transfer calls to read states

Follow-up to #1734.

pkg/compiler/native_test.go

@@ -260,7 +260,11 @@ func testContractCall(t *testing.T, hash util.Uint160, md interop.MethodAndPrice
 		require.Equal(t, md.MD.Name, method)
 
 		fs := callflag.CallFlag(int32(v.Estack().Pop().BigInt().Int64()))
-		require.Equal(t, md.RequiredFlags, fs)
+		extended := md.RequiredFlags // In some (all?) cases it's desirable to have Read permissions where Write is also allowed.
+		if md.RequiredFlags&callflag.WriteStates != 0 {
+			extended |= callflag.ReadStates
+		}
+		require.True(t, fs == md.RequiredFlags || fs == extended)
 
 		args := v.Estack().Pop().Array()
 		require.Equal(t, len(md.MD.Parameters), len(args))

pkg/interop/native/gas/gas.go

@@ -31,5 +31,5 @@ func BalanceOf(addr interop.Hash160) int {
 // Transfer represents `transfer` method of GAS native contract.
 func Transfer(from, to interop.Hash160, amount int, data interface{}) bool {
 	return contract.Call(interop.Hash160(Hash), "transfer",
-		contract.WriteStates|contract.AllowCall|contract.AllowNotify, from, to, amount, data).(bool)
+		contract.All, from, to, amount, data).(bool)
 }

pkg/interop/native/nameservice/name_service.go

@@ -65,7 +65,7 @@ func TokensOf(addr interop.Hash160) iterator.Iterator {
 // Transfer represents `transfer` method of NameService native contract.
 func Transfer(to interop.Hash160, tokenID string) bool {
 	return contract.Call(interop.Hash160(Hash), "transfer",
-		contract.WriteStates|contract.AllowNotify, to, tokenID).(bool)
+		contract.ReadStates|contract.WriteStates|contract.AllowNotify, to, tokenID).(bool)
 }
 
 // AddRoot represents `addRoot` method of NameService native contract.

pkg/interop/native/neo/neo.go

@@ -31,7 +31,7 @@ func BalanceOf(addr interop.Hash160) int {
 // Transfer represents `transfer` method of NEO native contract.
 func Transfer(from, to interop.Hash160, amount int, data interface{}) bool {
 	return contract.Call(interop.Hash160(Hash), "transfer",
-		contract.WriteStates|contract.AllowCall|contract.AllowNotify, from, to, amount, data).(bool)
+		contract.All, from, to, amount, data).(bool)
 }
 
 // GetCommittee represents `getCommittee` method of NEO native contract.