package ethvm // TODO Re write VM to use values instead of big integers? import ( "math/big" "github.com/ethereum/eth-go/ethstate" "github.com/ethereum/eth-go/ethutil" ) type ClosureRef interface { ReturnGas(*big.Int, *big.Int) Address() []byte Object() *ethstate.StateObject GetStorage(*big.Int) *ethutil.Value SetStorage(*big.Int, *ethutil.Value) } // Basic inline closure object which implement the 'closure' interface type Closure struct { caller ClosureRef object *ethstate.StateObject Code []byte message *ethstate.Message Gas, UsedGas, Price *big.Int Args []byte } // Create a new closure for the given data items func NewClosure(msg *ethstate.Message, caller ClosureRef, object *ethstate.StateObject, code []byte, gas, price *big.Int) *Closure { c := &Closure{message: msg, caller: caller, object: object, Code: code, Args: nil} // Gas should be a pointer so it can safely be reduced through the run // This pointer will be off the state transition c.Gas = gas //new(big.Int).Set(gas) // In most cases price and value are pointers to transaction objects // and we don't want the transaction's values to change. c.Price = new(big.Int).Set(price) c.UsedGas = new(big.Int) return c } // Retuns the x element in data slice func (c *Closure) GetStorage(x *big.Int) *ethutil.Value { m := c.object.GetStorage(x) if m == nil { return ethutil.EmptyValue() } return m } func (c *Closure) Get(x *big.Int) *ethutil.Value { return c.Gets(x, big.NewInt(1)) } func (c *Closure) Gets(x, y *big.Int) *ethutil.Value { if x.Int64() >= int64(len(c.Code)) || y.Int64() >= int64(len(c.Code)) { return ethutil.NewValue(0) } partial := c.Code[x.Int64() : x.Int64()+y.Int64()] return ethutil.NewValue(partial) } func (c *Closure) SetStorage(x *big.Int, val *ethutil.Value) { c.object.SetStorage(x, val) } func (c *Closure) Address() []byte { return c.object.Address() } func (c *Closure) Call(vm *Vm, args []byte) ([]byte, *big.Int, error) { c.Args = args ret, err := vm.RunClosure(c) return ret, c.UsedGas, err } func (c *Closure) Return(ret []byte) []byte { // Return the remaining gas to the caller c.caller.ReturnGas(c.Gas, c.Price) return ret } func (c *Closure) UseGas(gas *big.Int) bool { if c.Gas.Cmp(gas) < 0 { return false } // Sub the amount of gas from the remaining c.Gas.Sub(c.Gas, gas) c.UsedGas.Add(c.UsedGas, gas) return true } // Implement the caller interface func (c *Closure) ReturnGas(gas, price *big.Int) { // Return the gas to the closure c.Gas.Add(c.Gas, gas) c.UsedGas.Sub(c.UsedGas, gas) } func (c *Closure) Object() *ethstate.StateObject { return c.object } func (c *Closure) Caller() ClosureRef { return c.caller }