vm

package
v1.6.4 Latest Latest
Warning

This package is not in the latest version of its module.

 Go to latest Published: Jun 1, 2017 License: GPL-3.0 Imports: 16 Imported by: 0

Documentation

Overview

Package vm implements the Ethereum Virtual Machine.

The vm package implements two EVMs, a byte code VM and a JIT VM. The BC (Byte Code) VM loops over a set of bytes and executes them according to the set of rules defined in the Ethereum yellow paper. When the BC VM is invoked it invokes the JIT VM in a separate goroutine and compiles the byte code in JIT instructions.

The JIT VM, when invoked, loops around a set of pre-defined instructions until it either runs of gas, causes an internal error, returns or stops.

The JIT optimiser attempts to pre-compile instructions in to chunks or segments such as multiple PUSH operations and static JUMPs. It does this by analysing the opcodes and attempts to match certain regions to known sets. Whenever the optimiser finds said segments it creates a new instruction and replaces the first occurrence in the sequence.

Index

Constants

View Source 
const (
	GasQuickStep   uint64 = 2
	GasFastestStep uint64 = 3
	GasFastStep    uint64 = 5
	GasMidStep     uint64 = 8
	GasSlowStep    uint64 = 10
	GasExtStep     uint64 = 20

	GasReturn       uint64 = 0
	GasStop         uint64 = 0
	GasContractByte uint64 = 200
)

Variables

View Source 
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")
)
View Source 
var PrecompiledContracts = map[common.Address]PrecompiledContract{
	common.BytesToAddress([]byte{1}): &ecrecover{},
	common.BytesToAddress([]byte{2}): &sha256hash{},
	common.BytesToAddress([]byte{3}): &ripemd160hash{},
	common.BytesToAddress([]byte{4}): &dataCopy{},
}

PrecompiledContracts contains the default set of ethereum contracts

Functions

func NewFrontierInstructionSet added in v1.6.2 

func NewFrontierInstructionSet() [256]operation

NewFrontierInstructionSet returns the frontier instructions that can be executed during the frontier phase.

func NewHomesteadInstructionSet added in v1.6.2 

func NewHomesteadInstructionSet() [256]operation

NewHomesteadInstructionSet returns the frontier and homestead instructions that can be executed during the homestead phase.

func NoopCanTransfer added in v1.5.5 

func NoopCanTransfer(db StateDB, from common.Address, balance *big.Int) bool

func NoopTransfer added in v1.5.5 

func NoopTransfer(db StateDB, from, to common.Address, amount *big.Int)

func RunPrecompiledContract added in v1.5.6 

func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contract) (ret []byte, err error)

RunPrecompile runs and evaluate the output of a precompiled contract defined in contracts.go

func WriteLogs added in v1.6.0 

func WriteLogs(writer io.Writer, logs []*types.Log)

WriteLogs writes vm logs in a readable format to the given writer

func WriteTrace added in v1.6.0 

func WriteTrace(writer io.Writer, logs []StructLog)

WriteTrace writes a formatted trace to the given writer

Types

type AccountRef added in v1.6.0 

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 added in v1.6.0 

func (ar AccountRef) Address() common.Address

Address casts AccountRef to a Address

type CallContext added in v1.5.5 

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 EVM depends on this context being implemented for doing subcalls and initialising new EVM contracts.

type CanTransferFunc added in v1.5.5 

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

type Config added in v1.4.0 

type Config struct {
	// Debug enabled debugging Interpreter options
	Debug bool
	// EnableJit enabled the JIT VM
	EnableJit bool
	// ForceJit forces the JIT VM
	ForceJit bool
	// Tracer is the op code logger
	Tracer Tracer
	// NoRecursion disabled Interpreter call, callcode,
	// delegate call and create.
	NoRecursion bool
	// Disable gas metering
	DisableGasMetering bool
	// Enable recording of SHA3/keccak preimages
	EnablePreimageRecording bool
	// JumpTable contains the EVM instruction table. This
	// may me left uninitialised and will be set the default
	// table.
	JumpTable [256]operation
}

Config are the configuration options for the Interpreter

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    *big.Int       // Provides information for GASLIMIT
	BlockNumber *big.Int       // Provides information for NUMBER
	Time        *big.Int       // Provides information for TIME
	Difficulty  *big.Int       // Provides information for DIFFICULTY
}

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

type Contract added in v1.3.1 

type Contract struct {
	// CallerAddress is the result of the caller which initialised this
	// contract. However when the "call method" is delegated this value
	// needs to be initialised to that of the caller's caller.
	CallerAddress common.Address

	Code     []byte
	CodeHash common.Hash
	CodeAddr *common.Address
	Input    []byte

	Gas uint64

	Args []byte

	DelegateCall bool
	// contains filtered or unexported fields
}

Contract represents an ethereum contract in the state database. It contains the the contract code, calling arguments. Contract implements ContractRef

func NewContract added in v1.3.1 

func NewContract(caller ContractRef, object ContractRef, value *big.Int, gas uint64) *Contract

NewContract returns a new contract environment for the execution of EVM.

func (*Contract) Address added in v1.3.1 

func (c *Contract) Address() common.Address

Address returns the contracts address

func (*Contract) AsDelegate added in v1.3.4 

func (c *Contract) AsDelegate() *Contract

AsDelegate sets the contract to be a delegate call and returns the current contract (for chaining calls)

func (*Contract) Caller added in v1.3.4 

func (c *Contract) Caller() common.Address

Caller returns the caller of the contract.

Caller will recursively call caller when the contract is a delegate call, including that of caller's caller.

func (*Contract) GetByte added in v1.3.1 

func (c *Contract) GetByte(n uint64) byte

GetByte returns the n'th byte in the contract's byte array

func (*Contract) GetOp added in v1.3.1 

func (c *Contract) GetOp(n uint64) OpCode

GetOp returns the n'th element in the contract's byte array

func (*Contract) SetCallCode added in v1.3.1 

func (self *Contract) SetCallCode(addr *common.Address, hash common.Hash, code []byte)

SetCallCode sets the code of the contract and address of the backing data object

func (*Contract) SetCode added in v1.3.1 

func (self *Contract) SetCode(hash common.Hash, code []byte)

SetCode sets the code to the contract

func (*Contract) UseGas added in v1.3.1 

func (c *Contract) UseGas(gas uint64) (ok bool)

UseGas attempts the use gas and subtracts it and returns true on success

func (*Contract) Value added in v1.3.4 

func (c *Contract) Value() *big.Int

Value returns the contracts value (sent to it from it's caller)

type ContractRef added in v1.3.1 

type ContractRef interface {
	Address() common.Address
}

ContractRef is a reference to the contract's backing object

type EVM added in v1.4.0 

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 added in v1.5.6 

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

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

func (*EVM) Call added in v1.5.6 

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.

func (*EVM) CallCode added in v1.5.6 

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

CallCode 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.

CallCode differs from Call in the sense that it executes the given address' code with the caller as context.

func (*EVM) Cancel added in v1.5.6 

func (evm *EVM) Cancel()

Cancel cancels any running EVM operation. This may be called concurrently and it's safe to be called multiple times.

func (*EVM) ChainConfig added in v1.5.6 

func (evm *EVM) ChainConfig() *params.ChainConfig

ChainConfig returns the evmironment's chain configuration

func (*EVM) Create added in v1.5.6 

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

Create creates a new contract using code as deployment code.

func (*EVM) DelegateCall added in v1.5.6 

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

DelegateCall executes the contract associated with the addr with the given input as parameters. It reverses the state in case of an execution error.

DelegateCall differs from CallCode in the sense that it executes the given address' code with the caller as context and the caller is set to the caller of the caller.

func (*EVM) Interpreter added in v1.5.6 

func (evm *EVM) Interpreter() *Interpreter

Interpreter returns the EVM interpreter

type GetHashFunc added in v1.5.5 

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 Interpreter added in v1.5.6 

type Interpreter struct {
	// contains filtered or unexported fields
}

Interpreter is used to run Ethereum based contracts and will utilise the passed evmironment to query external sources for state information. The Interpreter will run the byte code VM or JIT VM based on the passed configuration.

func NewInterpreter added in v1.5.6 

func NewInterpreter(evm *EVM, cfg Config) *Interpreter

NewInterpreter returns a new instance of the Interpreter.

func (*Interpreter) Run added in v1.5.6 

func (in *Interpreter) Run(snapshot int, contract *Contract, input []byte) (ret []byte, err error)

Run loops and evaluates the contract's code with the given input data and returns the return byte-slice and an error if one occurred.

It's important to note that any errors returned by the interpreter should be considered a revert-and-consume-all-gas operation. No error specific checks should be handled to reduce complexity and errors further down the in.

type LogConfig added in v1.4.0 

type LogConfig struct {
	DisableMemory  bool // disable memory capture
	DisableStack   bool // disable stack capture
	DisableStorage bool // disable storage capture
	FullStorage    bool // show full storage (slow)
	Limit          int  // maximum length of output, but zero means unlimited
}

LogConfig are the configuration options for structured logger the EVM

type Memory 

type Memory struct {
	// contains filtered or unexported fields
}

Memory implements a simple memory model for the ethereum virtual machine.

func NewMemory 

func NewMemory() *Memory

func (*Memory) Data 

func (m *Memory) Data() []byte

Data returns the backing slice

func (*Memory) Get 

func (self *Memory) Get(offset, size int64) (cpy []byte)

Get returns offset + size as a new slice

func (*Memory) GetPtr 

func (self *Memory) GetPtr(offset, size int64) []byte

GetPtr returns the offset + size

func (*Memory) Len 

func (m *Memory) Len() int

Len returns the length of the backing slice

func (*Memory) Print 

func (m *Memory) Print()

func (*Memory) Resize 

func (m *Memory) Resize(size uint64)

Resize resizes the memory to size

func (*Memory) Set 

func (m *Memory) Set(offset, size uint64, value []byte)

Set sets offset + size to value

type NoopEVMCallContext added in v1.5.5 

type NoopEVMCallContext struct{}

func (NoopEVMCallContext) Call added in v1.5.5 

func (NoopEVMCallContext) Call(caller ContractRef, addr common.Address, data []byte, gas, value *big.Int) ([]byte, error)

func (NoopEVMCallContext) CallCode added in v1.5.5 

func (NoopEVMCallContext) CallCode(caller ContractRef, addr common.Address, data []byte, gas, value *big.Int) ([]byte, error)

func (NoopEVMCallContext) Create added in v1.5.5 

func (NoopEVMCallContext) Create(caller ContractRef, data []byte, gas, value *big.Int) ([]byte, common.Address, error)

func (NoopEVMCallContext) DelegateCall added in v1.5.5 

func (NoopEVMCallContext) DelegateCall(me ContractRef, addr common.Address, data []byte, gas *big.Int) ([]byte, error)

type NoopStateDB added in v1.5.5 

type NoopStateDB struct{}

func (NoopStateDB) AddBalance added in v1.5.5 

func (NoopStateDB) AddBalance(common.Address, *big.Int)

func (NoopStateDB) AddLog added in v1.5.5 

func (NoopStateDB) AddLog(*types.Log)

func (NoopStateDB) AddPreimage added in v1.5.8 

func (NoopStateDB) AddPreimage(common.Hash, []byte)

func (NoopStateDB) AddRefund added in v1.5.5 

func (NoopStateDB) AddRefund(*big.Int)

func (NoopStateDB) CreateAccount added in v1.5.5 

func (NoopStateDB) CreateAccount(common.Address)

func (NoopStateDB) Empty added in v1.5.5 

func (NoopStateDB) Empty(common.Address) bool

func (NoopStateDB) Exist added in v1.5.5 

func (NoopStateDB) Exist(common.Address) bool

func (NoopStateDB) ForEachStorage added in v1.6.0 

func (NoopStateDB) ForEachStorage(common.Address, func(common.Hash, common.Hash) bool)

func (NoopStateDB) GetBalance added in v1.5.5 

func (NoopStateDB) GetBalance(common.Address) *big.Int

func (NoopStateDB) GetCode added in v1.5.5 

func (NoopStateDB) GetCode(common.Address) []byte

func (NoopStateDB) GetCodeHash added in v1.5.5 

func (NoopStateDB) GetCodeHash(common.Address) common.Hash

func (NoopStateDB) GetCodeSize added in v1.5.5 

func (NoopStateDB) GetCodeSize(common.Address) int

func (NoopStateDB) GetNonce added in v1.5.5 

func (NoopStateDB) GetNonce(common.Address) uint64

func (NoopStateDB) GetRefund added in v1.5.5 

func (NoopStateDB) GetRefund() *big.Int

func (NoopStateDB) GetState added in v1.5.5 

func (NoopStateDB) GetState(common.Address, common.Hash) common.Hash

func (NoopStateDB) HasSuicided added in v1.5.5 

func (NoopStateDB) HasSuicided(common.Address) bool

func (NoopStateDB) RevertToSnapshot added in v1.5.5 

func (NoopStateDB) RevertToSnapshot(int)

func (NoopStateDB) SetCode added in v1.5.5 

func (NoopStateDB) SetCode(common.Address, []byte)

func (NoopStateDB) SetNonce added in v1.5.5 

func (NoopStateDB) SetNonce(common.Address, uint64)

func (NoopStateDB) SetState added in v1.5.5 

func (NoopStateDB) SetState(common.Address, common.Hash, common.Hash)

func (NoopStateDB) Snapshot added in v1.5.5 

func (NoopStateDB) Snapshot() int

func (NoopStateDB) SubBalance added in v1.5.5 

func (NoopStateDB) SubBalance(common.Address, *big.Int)

func (NoopStateDB) Suicide added in v1.5.5 

func (NoopStateDB) Suicide(common.Address) bool

type OpCode 

type OpCode byte

OpCode is an EVM opcode 

const (
	// 0x0 range - arithmetic ops
	STOP OpCode = iota
	ADD
	MUL
	SUB
	DIV
	SDIV
	MOD
	SMOD
	ADDMOD
	MULMOD
	EXP
	SIGNEXTEND
)
const (
	LT OpCode = iota + 0x10
	GT
	SLT
	SGT
	EQ
	ISZERO
	AND
	OR
	XOR
	NOT
	BYTE

	SHA3 = 0x20
)
const (
	// 0x30 range - closure state
	ADDRESS OpCode = 0x30 + iota
	BALANCE
	ORIGIN
	CALLER
	CALLVALUE
	CALLDATALOAD
	CALLDATASIZE
	CALLDATACOPY
	CODESIZE
	CODECOPY
	GASPRICE
	EXTCODESIZE
	EXTCODECOPY
)
const (

	// 0x40 range - block operations
	BLOCKHASH OpCode = 0x40 + iota
	COINBASE
	TIMESTAMP
	NUMBER
	DIFFICULTY
	GASLIMIT
)
const (
	// 0x50 range - 'storage' and execution
	POP OpCode = 0x50 + iota
	MLOAD
	MSTORE
	MSTORE8
	SLOAD
	SSTORE
	JUMP
	JUMPI
	PC
	MSIZE
	GAS
	JUMPDEST
)
const (
	// 0x60 range
	PUSH1 OpCode = 0x60 + iota
	PUSH2
	PUSH3
	PUSH4
	PUSH5
	PUSH6
	PUSH7
	PUSH8
	PUSH9
	PUSH10
	PUSH11
	PUSH12
	PUSH13
	PUSH14
	PUSH15
	PUSH16
	PUSH17
	PUSH18
	PUSH19
	PUSH20
	PUSH21
	PUSH22
	PUSH23
	PUSH24
	PUSH25
	PUSH26
	PUSH27
	PUSH28
	PUSH29
	PUSH30
	PUSH31
	PUSH32
	DUP1
	DUP2
	DUP3
	DUP4
	DUP5
	DUP6
	DUP7
	DUP8
	DUP9
	DUP10
	DUP11
	DUP12
	DUP13
	DUP14
	DUP15
	DUP16
	SWAP1
	SWAP2
	SWAP3
	SWAP4
	SWAP5
	SWAP6
	SWAP7
	SWAP8
	SWAP9
	SWAP10
	SWAP11
	SWAP12
	SWAP13
	SWAP14
	SWAP15
	SWAP16
)
const (
	LOG0 OpCode = 0xa0 + iota
	LOG1
	LOG2
	LOG3
	LOG4
)
const (
	PUSH OpCode = 0xb0 + iota
	DUP
	SWAP
)

unofficial opcodes used for parsing 

const (
	// 0xf0 range - closures
	CREATE OpCode = 0xf0 + iota
	CALL
	CALLCODE
	RETURN
	DELEGATECALL

	SELFDESTRUCT = 0xff
)

func StringToOp 

func StringToOp(str string) OpCode

func (OpCode) IsPush added in v1.3.1 

func (op OpCode) IsPush() bool

func (OpCode) IsStaticJump added in v1.3.1 

func (op OpCode) IsStaticJump() bool

func (OpCode) String 

func (o OpCode) String() string

type PrecompiledContract added in v1.5.6 

type PrecompiledContract interface {
	RequiredGas(input []byte) uint64  // RequiredPrice calculates the contract gas use
	Run(input []byte) ([]byte, error) // Run runs the precompiled contract
}

Precompiled contract is the basic interface for native Go contracts. The implementation requires a deterministic gas count based on the input size of the Run method of the contract.

type Stack added in v1.5.0 

type Stack struct {
	// contains filtered or unexported fields
}

stack is an object for basic stack operations. Items popped to the stack are expected to be changed and modified. stack does not take care of adding newly initialised objects.

func (*Stack) Back added in v1.5.6 

func (st *Stack) Back(n int) *big.Int

Back returns the n'th item in stack

func (*Stack) Data added in v1.5.0 

func (st *Stack) Data() []*big.Int

func (*Stack) Print added in v1.5.0 

func (st *Stack) Print()

type StateDB added in v1.5.5 

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(*big.Int)
	GetRefund() *big.Int

	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)

	ForEachStorage(common.Address, func(common.Hash, common.Hash) bool)
}

StateDB is an EVM database for full state querying.

type Storage added in v1.4.0 

type Storage map[common.Hash]common.Hash

func (Storage) Copy added in v1.4.0 

func (self Storage) Copy() Storage

type StructLog 

type StructLog struct {
	Pc      uint64
	Op      OpCode
	Gas     uint64
	GasCost uint64
	Memory  []byte
	Stack   []*big.Int
	Storage map[common.Hash]common.Hash
	Depth   int
	Err     error
}

StructLog is emitted to the EVM each cycle and lists information about the current internal state prior to the execution of the statement.

type StructLogger added in v1.5.0 

type StructLogger struct {
	// contains filtered or unexported fields
}

StructLogger is an EVM state logger and implements Tracer.

StructLogger can capture state based on the given Log configuration and also keeps a track record of modified storage which is used in reporting snapshots of the contract their storage.

func NewStructLogger added in v1.5.0 

func NewStructLogger(cfg *LogConfig) *StructLogger

NewLogger returns a new logger

func (*StructLogger) CaptureState added in v1.5.0 

func (l *StructLogger) CaptureState(env *EVM, pc uint64, op OpCode, gas, cost uint64, memory *Memory, stack *Stack, contract *Contract, depth int, err error) error

captureState logs a new structured log message and pushes it out to the environment

captureState also tracks SSTORE ops to track dirty values.

func (*StructLogger) StructLogs added in v1.5.0 

func (l *StructLogger) StructLogs() []StructLog

StructLogs returns a list of captured log entries

type Tracer added in v1.5.0 

type Tracer interface {
	CaptureState(env *EVM, pc uint64, op OpCode, gas, cost uint64, memory *Memory, stack *Stack, contract *Contract, depth int, err error) error
}

Tracer is used to collect execution traces from an EVM transaction execution. CaptureState is called for each step of the VM with the current VM state. Note that reference types are actual VM data structures; make copies if you need to retain them beyond the current call.

type TransferFunc added in v1.5.5 

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

Source Files

View all Source files

Directories

Path Synopsis
Package runtime provides a basic execution model for executing EVM code.
 Package runtime provides a basic execution model for executing EVM code.

Jump to

Keyboard shortcuts

? : This menu
/ : Search site
f or F : Jump to
y or Y : Canonical URL
go.dev uses cookies from Google to deliver and enhance the quality of its services and to analyze traffic. Learn more.