path: root/ethvm/execution.go

package ethvm

import (
    "fmt"
    "math/big"

    "github.com/ethereum/eth-go/ethstate"
    "github.com/ethereum/eth-go/ethutil"
)

type Execution struct {
    vm                VirtualMachine
    closure           *Closure
    address, input    []byte
    gas, price, value *big.Int
    object            *ethstate.StateObject
}

func NewExecution(vm VirtualMachine, address, input []byte, gas, gasPrice, value *big.Int) *Execution {
    return &Execution{vm: vm, address: address, input: input, gas: gas, price: gasPrice, value: value}
}

func (self *Execution) Addr() []byte {
    return self.address
}

func (self *Execution) Exec(codeAddr []byte, caller ClosureRef) (ret []byte, err error) {
    env := self.vm.Env()

    snapshot := env.State().Copy()

    msg := env.State().Manifest().AddMessage(&ethstate.Message{
        To: self.address, From: caller.Address(),
        Input:  self.input,
        Origin: env.Origin(),
        Block:  env.BlockHash(), Timestamp: env.Time(), Coinbase: env.Coinbase(), Number: env.BlockNumber(),
        Value: self.value,
    })

    object := caller.Object()
    if object.Balance.Cmp(self.value) < 0 {
        caller.ReturnGas(self.gas, self.price)

        err = fmt.Errorf("Insufficient funds to transfer value. Req %v, has %v", self.value, object.Balance)
    } else {
        stateObject := env.State().GetOrNewStateObject(self.address)
        self.object = stateObject

        caller.Object().SubAmount(self.value)
        stateObject.AddAmount(self.value)

        // Precompiled contracts (address.go) 1, 2 & 3.
        naddr := ethutil.BigD(codeAddr).Uint64()
        if p := Precompiled[naddr]; p != nil {
            if self.gas.Cmp(p.Gas) >= 0 {
                ret = p.Call(self.input)
                self.vm.Printf("NATIVE_FUNC(%x) => %x", naddr, ret)
            }
        } else {
            if self.vm.Depth() == MaxCallDepth {
                return nil, fmt.Errorf("Max call depth exceeded (%d)", MaxCallDepth)
            }

            // Retrieve the executing code
            code := env.State().GetCode(codeAddr)

            // Create a new callable closure
            c := NewClosure(msg, caller, stateObject, code, self.gas, self.price)
            c.exe = self
            // Executer the closure and get the return value (if any)
            ret, _, err = c.Call(self.vm, self.input)

            msg.Output = ret
        }
    }

    if err != nil {
        env.State().Set(snapshot)
    }

    return
}