path: root/vm/execution.go

package vm

import (
    "fmt"
    "math/big"

    "github.com/ethereum/go-ethereum/ethutil"
    "github.com/ethereum/go-ethereum/state"
)

type Execution struct {
    vm                VirtualMachine
    address, input    []byte
    Gas, price, value *big.Int
    object            *state.StateObject
    SkipTransfer      bool
}

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) ([]byte, error) {
    // Retrieve the executing code
    code := self.vm.Env().State().GetCode(codeAddr)

    return self.exec(code, codeAddr, caller)
}

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

    vmlogger.Debugf("pre state %x\n", env.State().Root())
    snapshot := env.State().Copy()
    defer func() {
        if IsDepthErr(err) || IsOOGErr(err) {
            env.State().Set(snapshot)
        }
        vmlogger.Debugf("post state %x\n", env.State().Root())
    }()

    msg := env.State().Manifest().AddMessage(&state.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,
    })

    from, to := caller.Object(), env.State().GetOrNewStateObject(self.address)
    // Skipping transfer is used on testing for the initial call
    if !self.SkipTransfer {
        err = env.Transfer(from, to, self.value)
    }

    if err != nil {
        caller.ReturnGas(self.Gas, self.price)

        err = fmt.Errorf("Insufficient funds to transfer value. Req %v, has %v", self.value, from.Balance)
    } else {
        self.object = to
        // Pre-compiled contracts (address.go) 1, 2 & 3.
        naddr := ethutil.BigD(caddr).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 {
            // Create a new callable closure
            c := NewClosure(msg, caller, to, code, self.Gas, self.price)
            c.exe = self

            if self.vm.Depth() == MaxCallDepth {
                c.UseGas(self.Gas)

                return c.Return(nil), DepthError{}
            }

            // Executer the closure and get the return value (if any)
            ret, _, err = c.Call(self.vm, self.input)
            msg.Output = ret
        }
    }

    return
}

func (self *Execution) Create(caller ClosureRef) (ret []byte, err error) {
    return self.exec(self.input, nil, caller)
}