plugeth/internal/ethapi/tracer.go
Jeffrey Wilcke 3fc7c97827 core, core/vm: implemented a generic environment (#3348)
Environment is now a struct (not an interface). This
reduces a lot of tech-debt throughout the codebase where a virtual
machine environment had to be implemented in order to test or run it.

The new environment is suitable to be used en the json tests, core
consensus and light client.
2016-12-06 02:16:03 +01:00

319 lines
8.9 KiB
Go

// Copyright 2016 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 ethapi
import (
"encoding/json"
"errors"
"fmt"
"math/big"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/vm"
"github.com/robertkrimen/otto"
)
// fakeBig is used to provide an interface to Javascript for 'big.NewInt'
type fakeBig struct{}
// NewInt creates a new big.Int with the specified int64 value.
func (fb *fakeBig) NewInt(x int64) *big.Int {
return big.NewInt(x)
}
// OpCodeWrapper provides a JavaScript-friendly wrapper around OpCode, to convince Otto to treat it
// as an object, instead of a number.
type opCodeWrapper struct {
op vm.OpCode
}
// toNumber returns the ID of this opcode as an integer
func (ocw *opCodeWrapper) toNumber() int {
return int(ocw.op)
}
// toString returns the string representation of the opcode
func (ocw *opCodeWrapper) toString() string {
return ocw.op.String()
}
// isPush returns true if the op is a Push
func (ocw *opCodeWrapper) isPush() bool {
return ocw.op.IsPush()
}
// MarshalJSON serializes the opcode as JSON
func (ocw *opCodeWrapper) MarshalJSON() ([]byte, error) {
return json.Marshal(ocw.op.String())
}
// toValue returns an otto.Value for the opCodeWrapper
func (ocw *opCodeWrapper) toValue(vm *otto.Otto) otto.Value {
value, _ := vm.ToValue(ocw)
obj := value.Object()
obj.Set("toNumber", ocw.toNumber)
obj.Set("toString", ocw.toString)
obj.Set("isPush", ocw.isPush)
return value
}
// memoryWrapper provides a JS wrapper around vm.Memory
type memoryWrapper struct {
memory *vm.Memory
}
// slice returns the requested range of memory as a byte slice
func (mw *memoryWrapper) slice(begin, end int64) []byte {
return mw.memory.Get(begin, end-begin)
}
// getUint returns the 32 bytes at the specified address interpreted
// as an unsigned integer
func (mw *memoryWrapper) getUint(addr int64) *big.Int {
ret := big.NewInt(0)
ret.SetBytes(mw.memory.GetPtr(addr, 32))
return ret
}
// toValue returns an otto.Value for the memoryWrapper
func (mw *memoryWrapper) toValue(vm *otto.Otto) otto.Value {
value, _ := vm.ToValue(mw)
obj := value.Object()
obj.Set("slice", mw.slice)
obj.Set("getUint", mw.getUint)
return value
}
// stackWrapper provides a JS wrapper around vm.Stack
type stackWrapper struct {
stack *vm.Stack
}
// peek returns the nth-from-the-top element of the stack.
func (sw *stackWrapper) peek(idx int) *big.Int {
return sw.stack.Data()[len(sw.stack.Data())-idx-1]
}
// length returns the length of the stack
func (sw *stackWrapper) length() int {
return len(sw.stack.Data())
}
// toValue returns an otto.Value for the stackWrapper
func (sw *stackWrapper) toValue(vm *otto.Otto) otto.Value {
value, _ := vm.ToValue(sw)
obj := value.Object()
obj.Set("peek", sw.peek)
obj.Set("length", sw.length)
return value
}
// dbWrapper provides a JS wrapper around vm.Database
type dbWrapper struct {
db vm.StateDB
}
// getBalance retrieves an account's balance
func (dw *dbWrapper) getBalance(addr common.Address) *big.Int {
return dw.db.GetBalance(addr)
}
// getNonce retrieves an account's nonce
func (dw *dbWrapper) getNonce(addr common.Address) uint64 {
return dw.db.GetNonce(addr)
}
// getCode retrieves an account's code
func (dw *dbWrapper) getCode(addr common.Address) []byte {
return dw.db.GetCode(addr)
}
// getState retrieves an account's state data for the given hash
func (dw *dbWrapper) getState(addr common.Address, hash common.Hash) common.Hash {
return dw.db.GetState(addr, hash)
}
// exists returns true iff the account exists
func (dw *dbWrapper) exists(addr common.Address) bool {
return dw.db.Exist(addr)
}
// toValue returns an otto.Value for the dbWrapper
func (dw *dbWrapper) toValue(vm *otto.Otto) otto.Value {
value, _ := vm.ToValue(dw)
obj := value.Object()
obj.Set("getBalance", dw.getBalance)
obj.Set("getNonce", dw.getNonce)
obj.Set("getCode", dw.getCode)
obj.Set("getState", dw.getState)
obj.Set("exists", dw.exists)
return value
}
// JavascriptTracer provides an implementation of Tracer that evaluates a
// Javascript function for each VM execution step.
type JavascriptTracer struct {
vm *otto.Otto // Javascript VM instance
traceobj *otto.Object // User-supplied object to call
log map[string]interface{} // (Reusable) map for the `log` arg to `step`
logvalue otto.Value // JS view of `log`
memory *memoryWrapper // Wrapper around the VM memory
memvalue otto.Value // JS view of `memory`
stack *stackWrapper // Wrapper around the VM stack
stackvalue otto.Value // JS view of `stack`
db *dbWrapper // Wrapper around the VM environment
dbvalue otto.Value // JS view of `db`
err error // Error, if one has occurred
}
// NewJavascriptTracer instantiates a new JavascriptTracer instance.
// code specifies a Javascript snippet, which must evaluate to an expression
// returning an object with 'step' and 'result' functions.
func NewJavascriptTracer(code string) (*JavascriptTracer, error) {
vm := otto.New()
vm.Interrupt = make(chan func(), 1)
// Set up builtins for this environment
vm.Set("big", &fakeBig{})
jstracer, err := vm.Object("(" + code + ")")
if err != nil {
return nil, err
}
// Check the required functions exist
step, err := jstracer.Get("step")
if err != nil {
return nil, err
}
if !step.IsFunction() {
return nil, fmt.Errorf("Trace object must expose a function step()")
}
result, err := jstracer.Get("result")
if err != nil {
return nil, err
}
if !result.IsFunction() {
return nil, fmt.Errorf("Trace object must expose a function result()")
}
// Create the persistent log object
log := make(map[string]interface{})
logvalue, _ := vm.ToValue(log)
// Create persistent wrappers for memory and stack
mem := &memoryWrapper{}
stack := &stackWrapper{}
db := &dbWrapper{}
return &JavascriptTracer{
vm: vm,
traceobj: jstracer,
log: log,
logvalue: logvalue,
memory: mem,
memvalue: mem.toValue(vm),
stack: stack,
stackvalue: stack.toValue(vm),
db: db,
dbvalue: db.toValue(vm),
err: nil,
}, nil
}
// Stop terminates execution of any JavaScript
func (jst *JavascriptTracer) Stop(err error) {
jst.vm.Interrupt <- func() {
panic(err)
}
}
// callSafely executes a method on a JS object, catching any panics and
// returning them as error objects.
func (jst *JavascriptTracer) callSafely(method string, argumentList ...interface{}) (ret interface{}, err error) {
defer func() {
if caught := recover(); caught != nil {
switch caught := caught.(type) {
case error:
err = caught
case string:
err = errors.New(caught)
case fmt.Stringer:
err = errors.New(caught.String())
default:
panic(caught)
}
}
}()
value, err := jst.traceobj.Call(method, argumentList...)
ret, _ = value.Export()
return ret, err
}
func wrapError(context string, err error) error {
var message string
switch err := err.(type) {
case *otto.Error:
message = err.String()
default:
message = err.Error()
}
return fmt.Errorf("%v in server-side tracer function '%v'", message, context)
}
// CaptureState implements the Tracer interface to trace a single step of VM execution
func (jst *JavascriptTracer) CaptureState(env *vm.Environment, pc uint64, op vm.OpCode, gas, cost *big.Int, memory *vm.Memory, stack *vm.Stack, contract *vm.Contract, depth int, err error) error {
if jst.err == nil {
jst.memory.memory = memory
jst.stack.stack = stack
jst.db.db = env.StateDB
ocw := &opCodeWrapper{op}
jst.log["pc"] = pc
jst.log["op"] = ocw.toValue(jst.vm)
jst.log["gas"] = gas.Int64()
jst.log["gasPrice"] = cost.Int64()
jst.log["memory"] = jst.memvalue
jst.log["stack"] = jst.stackvalue
jst.log["depth"] = depth
jst.log["account"] = contract.Address()
jst.log["err"] = err
_, err := jst.callSafely("step", jst.logvalue, jst.dbvalue)
if err != nil {
jst.err = wrapError("step", err)
}
}
return nil
}
// GetResult calls the Javascript 'result' function and returns its value, or any accumulated error
func (jst *JavascriptTracer) GetResult() (result interface{}, err error) {
if jst.err != nil {
return nil, jst.err
}
result, err = jst.callSafely("result")
if err != nil {
err = wrapError("result", err)
}
return
}