vm

Documentation

Index

• Variables
• type AccountRef
  • func (ar AccountRef) Address() common.Address
• type CallContext
• type CanTransferFunc
• type Context
• type ContractRef
• type EVM
  • func NewEVM(ctx Context, statedb StateDB, chainConfig *params.ChainConfig) *EVM
  • func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas uint64, ...) (ret []byte, leftOverGas uint64, err error)
• type GetHashFunc
• type StateDB
• type TransferFunc

Variables

var (
	ErrOutOfGas                 = errors.New("out of gas")
	ErrCodeStoreOutOfGas        = errors.New("contract creation code storage out of gas")
	ErrDepth                    = errors.New("max call depth exceeded")
	ErrTraceLimitReached        = errors.New("the number of logs reached the specified limit")
	ErrInsufficientBalance      = errors.New("insufficient balance for transfer")
	ErrContractAddressCollision = errors.New("contract address collision")
	ErrNoCompatibleInterpreter  = errors.New("no compatible interpreter")
)

List execution errors

Types

type AccountRef

type AccountRef common.Address

AccountRef implements ContractRef.

Account references are used during EVM initialisation and it's primary use is to fetch addresses. Removing this object proves difficult because of the cached jump destinations which are fetched from the parent contract (i.e. the caller), which is a ContractRef.

func (AccountRef) Address

func (ar AccountRef) Address() common.Address

Address casts AccountRef to a Address

type CallContext

type CallContext interface {
	// Call another contract
	Call(env *EVM, me ContractRef, addr common.Address, data []byte, gas, value *big.Int) ([]byte, error)
	// Take another's contract code and execute within our own context
	CallCode(env *EVM, me ContractRef, addr common.Address, data []byte, gas, value *big.Int) ([]byte, error)
	// Same as CallCode except sender and value is propagated from parent to child scope
	DelegateCall(env *EVM, me ContractRef, addr common.Address, data []byte, gas *big.Int) ([]byte, error)
	// Create a new contract
	Create(env *EVM, me ContractRef, data []byte, gas, value *big.Int) ([]byte, common.Address, error)
}

CallContext provides a basic interface for the EVM calling conventions. The EVM depends on this context being implemented for doing subcalls and initialising new EVM contracts.

type CanTransferFunc

type CanTransferFunc func(StateDB, common.Address, *big.Int) bool

CanTransferFunc is the signature of a transfer guard function

type Context

type Context struct {
	// CanTransfer returns whether the account contains
	// sufficient ether to transfer the value
	CanTransfer CanTransferFunc
	// Transfer transfers ether from one account to the other
	Transfer TransferFunc
	// GetHash returns the hash corresponding to n
	GetHash GetHashFunc

	// Message information
	Origin   common.Address // Provides information for ORIGIN
	GasPrice *big.Int       // Provides information for GASPRICE

	// Block information
	Coinbase    common.Address // Provides information for COINBASE
	GasLimit    uint64         // Provides information for GASLIMIT
	BlockNumber *big.Int       // Provides information for NUMBER
	Difficulty  *big.Int       // Provides information for DIFFICULTY
}

Context provides the EVM with auxiliary information. Once provided it shouldn't be modified.

type ContractRef

type ContractRef interface {
	Address() common.Address
}

ContractRef is a reference to the contract's backing object

type EVM

type EVM struct {
	// Context provides auxiliary blockchain related information
	Context
	// StateDB gives access to the underlying state
	StateDB StateDB
	// contains filtered or unexported fields
}

EVM is the Ethereum Virtual Machine base object and provides the necessary tools to run a contract on the given state with the provided context. It should be noted that any error generated through any of the calls should be considered a revert-state-and-consume-all-gas operation, no checks on specific errors should ever be performed. The interpreter makes sure that any errors generated are to be considered faulty code.

The EVM should never be reused and is not thread safe.

func NewEVM

func NewEVM(ctx Context, statedb StateDB, chainConfig *params.ChainConfig) *EVM

NewEVM returns a new EVM. The returned EVM is not thread safe and should only ever be used *once*.

func (*EVM) Call

func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas uint64, value *big.Int) (ret []byte, leftOverGas uint64, err error)

Call executes the contract associated with the addr with the given input as parameters. It also handles any necessary value transfer required and takes the necessary steps to create accounts and reverses the state in case of an execution error or failed value transfer.

type GetHashFunc

type GetHashFunc func(uint64) common.Hash

GetHashFunc returns the nth block hash in the blockchain and is used by the BLOCKHASH EVM op code.

type StateDB

type StateDB interface {
	CreateAccount(common.Address)

	SubBalance(common.Address, *big.Int)
	AddBalance(common.Address, *big.Int)
	GetBalance(common.Address) *big.Int

	GetNonce(common.Address) uint64
	SetNonce(common.Address, uint64)

	GetCodeHash(common.Address) common.Hash
	GetCode(common.Address) []byte
	SetCode(common.Address, []byte)
	GetCodeSize(common.Address) int

	AddRefund(uint64)
	SubRefund(uint64)
	GetRefund() uint64

	GetCommittedState(common.Address, common.Hash) common.Hash
	GetState(common.Address, common.Hash) common.Hash
	SetState(common.Address, common.Hash, common.Hash)

	Suicide(common.Address) bool
	HasSuicided(common.Address) bool

	// Exist reports whether the given account exists in state.
	// Notably this should also return true for suicided accounts.
	Exist(common.Address) bool
	// Empty returns whether the given account is empty. Empty
	// is defined according to EIP161 (balance = nonce = code = 0).
	Empty(common.Address) bool

	RevertToSnapshot(int)
	Snapshot() int

	AddLog(*types.Log)
	AddPreimage(common.Hash, []byte)
}

StateDB is an EVM database for full state querying.

type TransferFunc

type TransferFunc func(StateDB, common.Address, common.Address, *big.Int)

TransferFunc is the signature of a transfer function