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// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package vm
import (
"fmt"
"math/big"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/math"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/params"
)
// Config are the configuration options for the Interpreter
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
}
// Interpreter is used to run Ethereum based contracts and will utilise the
// passed environment to query external sources for state information.
// The Interpreter will run the byte code VM or JIT VM based on the passed
// configuration.
type Interpreter struct {
env *EVM
cfg Config
gasTable params.GasTable
intPool *intPool
}
// NewInterpreter returns a new instance of the Interpreter.
func NewInterpreter(env *EVM, cfg Config) *Interpreter {
// We use the STOP instruction whether to see
// the jump table was initialised. If it was not
// we'll set the default jump table.
if !cfg.JumpTable[STOP].valid {
cfg.JumpTable = defaultJumpTable
}
return &Interpreter{
env: env,
cfg: cfg,
gasTable: env.ChainConfig().GasTable(env.BlockNumber),
intPool: newIntPool(),
}
}
// Run loops and evaluates the contract's code with the given input data
func (evm *Interpreter) Run(contract *Contract, input []byte) (ret []byte, err error) {
evm.env.depth++
defer func() { evm.env.depth-- }()
if contract.CodeAddr != nil {
if p := PrecompiledContracts[*contract.CodeAddr]; p != nil {
return RunPrecompiledContract(p, input, contract)
}
}
// Don't bother with the execution if there's no code.
if len(contract.Code) == 0 {
return nil, nil
}
codehash := contract.CodeHash // codehash is used when doing jump dest caching
if codehash == (common.Hash{}) {
codehash = crypto.Keccak256Hash(contract.Code)
}
var (
op OpCode // current opcode
mem = NewMemory() // bound memory
stack = newstack() // local stack
// For optimisation reason we're using uint64 as the program counter.
// It's theoretically possible to go above 2^64. The YP defines the PC to be uint256. Practically much less so feasible.
pc = uint64(0) // program counter
cost uint64
)
contract.Input = input
// User defer pattern to check for an error and, based on the error being nil or not, use all gas and return.
defer func() {
if err != nil && evm.cfg.Debug {
// XXX For debugging
//fmt.Printf("%04d: %8v cost = %-8d stack = %-8d ERR = %v\n", pc, op, cost, stack.len(), err)
// TODO update the tracer
g, c := new(big.Int).SetUint64(contract.Gas), new(big.Int).SetUint64(cost)
evm.cfg.Tracer.CaptureState(evm.env, pc, op, g, c, mem, stack, contract, evm.env.depth, err)
}
}()
log.Debug("EVM running contract", "hash", codehash[:])
tstart := time.Now()
defer log.Debug("EVM finished running contract", "hash", codehash[:], "elapsed", time.Since(tstart))
// The Interpreter main run loop (contextual). This loop runs until either an
// explicit STOP, RETURN or SELFDESTRUCT is executed, an error occurred during
// the execution of one of the operations or until the evm.done is set by
// the parent context.Context.
for atomic.LoadInt32(&evm.env.abort) == 0 {
// Get the memory location of pc
op = contract.GetOp(pc)
// get the operation from the jump table matching the opcode
operation := evm.cfg.JumpTable[op]
// if the op is invalid abort the process and return an error
if !operation.valid {
return nil, fmt.Errorf("invalid opcode %x", op)
}
// validate the stack and make sure there enough stack items available
// to perform the operation
if err := operation.validateStack(stack); err != nil {
return nil, err
}
var memorySize uint64
// calculate the new memory size and expand the memory to fit
// the operation
if operation.memorySize != nil {
memSize, overflow := bigUint64(operation.memorySize(stack))
if overflow {
return nil, errGasUintOverflow
}
// memory is expanded in words of 32 bytes. Gas
// is also calculated in words.
if memorySize, overflow = math.SafeMul(toWordSize(memSize), 32); overflow {
return nil, errGasUintOverflow
}
}
if !evm.cfg.DisableGasMetering {
// consume the gas and return an error if not enough gas is available.
// cost is explicitly set so that the capture state defer method cas get the proper cost
cost, err = operation.gasCost(evm.gasTable, evm.env, contract, stack, mem, memorySize)
if err != nil || !contract.UseGas(cost) {
return nil, ErrOutOfGas
}
}
if memorySize > 0 {
mem.Resize(memorySize)
}
if evm.cfg.Debug {
g, c := new(big.Int).SetUint64(contract.Gas), new(big.Int).SetUint64(cost)
evm.cfg.Tracer.CaptureState(evm.env, pc, op, g, c, mem, stack, contract, evm.env.depth, err)
}
// XXX For debugging
//fmt.Printf("%04d: %8v cost = %-8d stack = %-8d\n", pc, op, cost, stack.len())
// execute the operation
res, err := operation.execute(&pc, evm.env, contract, mem, stack)
// verifyPool is a build flag. Pool verification makes sure the integrity
// of the integer pool by comparing values to a default value.
if verifyPool {
verifyIntegerPool(evm.intPool)
}
switch {
case err != nil:
return nil, err
case operation.halts:
return res, nil
case !operation.jumps:
pc++
}
}
return nil, nil
}
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