package ethchain // TODO Re write VM to use values instead of big integers? import ( "github.com/ethereum/eth-go/ethutil" "math/big" ) type ClosureRef interface { ReturnGas(*big.Int, *big.Int, *State) Address() []byte GetStorage(*big.Int) *ethutil.Value SetStorage(*big.Int, *ethutil.Value) N() *big.Int } // Basic inline closure object which implement the 'closure' interface type Closure struct { caller ClosureRef object *StateObject Script []byte State *State Gas, UsedGas, Price *big.Int Args []byte } // Create a new closure for the given data items func NewClosure(caller ClosureRef, object *StateObject, script []byte, state *State, gas, price *big.Int) *Closure { c := &Closure{caller: caller, object: object, Script: script, State: state, 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.Script)) || y.Int64() >= int64(len(c.Script)) { return ethutil.NewValue(0) } partial := c.Script[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() } type DebugHook func(step int, op OpCode, mem *Memory, stack *Stack, stateObject *StateObject) bool func (c *Closure) Call(vm *Vm, args []byte, hook DebugHook) ([]byte, *big.Int, error) { c.Args = args ret, err := vm.RunClosure(c, hook) return ret, c.UsedGas, err } func (c *Closure) Return(ret []byte) []byte { // Return the remaining gas to the caller // If no caller is present return it to // the origin (i.e. contract or tx) if c.caller != nil { c.caller.ReturnGas(c.Gas, c.Price, c.State) } else { c.object.ReturnGas(c.Gas, c.Price, c.State) } 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, state *State) { // Return the gas to the closure c.Gas.Add(c.Gas, gas) c.UsedGas.Sub(c.UsedGas, gas) } func (c *Closure) Object() *StateObject { return c.object } func (c *Closure) Caller() ClosureRef { return c.caller } func (c *Closure) N() *big.Int { return c.object.N() }