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// Copyright 2015 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"
"os"
"unicode"
"github.com/ethereum/go-ethereum/common"
)
type Storage map[common.Hash]common.Hash
func (self Storage) Copy() Storage {
cpy := make(Storage)
for key, value := range self {
cpy[key] = value
}
return cpy
}
// LogConfig are the configuration options for structured logger the EVM
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
}
// StructLog is emitted to the Environment each cycle and lists information about the current internal state
// prior to the execution of the statement.
type StructLog struct {
Pc uint64
Op OpCode
Gas *big.Int
GasCost *big.Int
Memory []byte
Stack []*big.Int
Storage map[common.Hash]common.Hash
Depth int
Err 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 Tracer interface {
CaptureState(env *Environment, pc uint64, op OpCode, gas, cost *big.Int, memory *Memory, stack *Stack, contract *Contract, depth int, err error) error
}
// 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.
type StructLogger struct {
cfg LogConfig
logs []StructLog
changedValues map[common.Address]Storage
}
// NewLogger returns a new logger
func NewStructLogger(cfg *LogConfig) *StructLogger {
logger := &StructLogger{
changedValues: make(map[common.Address]Storage),
}
if cfg != nil {
logger.cfg = *cfg
}
return logger
}
// captureState logs a new structured log message and pushes it out to the environment
//
// captureState also tracks SSTORE ops to track dirty values.
func (l *StructLogger) CaptureState(env *Environment, pc uint64, op OpCode, gas, cost *big.Int, memory *Memory, stack *Stack, contract *Contract, depth int, err error) error {
// check if already accumulated the specified number of logs
if l.cfg.Limit != 0 && l.cfg.Limit <= len(l.logs) {
return TraceLimitReachedError
}
// initialise new changed values storage container for this contract
// if not present.
if l.changedValues[contract.Address()] == nil {
l.changedValues[contract.Address()] = make(Storage)
}
// capture SSTORE opcodes and determine the changed value and store
// it in the local storage container. NOTE: we do not need to do any
// range checks here because that's already handler prior to calling
// this function.
switch op {
case SSTORE:
var (
value = common.BigToHash(stack.data[stack.len()-2])
address = common.BigToHash(stack.data[stack.len()-1])
)
l.changedValues[contract.Address()][address] = value
}
// copy a snapstot of the current memory state to a new buffer
var mem []byte
if !l.cfg.DisableMemory {
mem = make([]byte, len(memory.Data()))
copy(mem, memory.Data())
}
// copy a snapshot of the current stack state to a new buffer
var stck []*big.Int
if !l.cfg.DisableStack {
stck = make([]*big.Int, len(stack.Data()))
for i, item := range stack.Data() {
stck[i] = new(big.Int).Set(item)
}
}
// Copy the storage based on the settings specified in the log config. If full storage
// is disabled (default) we can use the simple Storage.Copy method, otherwise we use
// the state object to query for all values (slow process).
var storage Storage
if !l.cfg.DisableStorage {
if l.cfg.FullStorage {
storage = make(Storage)
// Get the contract account and loop over each storage entry. This may involve looping over
// the trie and is a very expensive process.
env.StateDB.GetAccount(contract.Address()).ForEachStorage(func(key, value common.Hash) bool {
storage[key] = value
// Return true, indicating we'd like to continue.
return true
})
} else {
// copy a snapshot of the current storage to a new container.
storage = l.changedValues[contract.Address()].Copy()
}
}
// create a new snaptshot of the EVM.
log := StructLog{pc, op, new(big.Int).Set(gas), cost, mem, stck, storage, env.Depth, err}
l.logs = append(l.logs, log)
return nil
}
// StructLogs returns a list of captured log entries
func (l *StructLogger) StructLogs() []StructLog {
return l.logs
}
// StdErrFormat formats a slice of StructLogs to human readable format
func StdErrFormat(logs []StructLog) {
fmt.Fprintf(os.Stderr, "VM STAT %d OPs\n", len(logs))
for _, log := range logs {
fmt.Fprintf(os.Stderr, "PC %08d: %s GAS: %v COST: %v", log.Pc, log.Op, log.Gas, log.GasCost)
if log.Err != nil {
fmt.Fprintf(os.Stderr, " ERROR: %v", log.Err)
}
fmt.Fprintf(os.Stderr, "\n")
fmt.Fprintln(os.Stderr, "STACK =", len(log.Stack))
for i := len(log.Stack) - 1; i >= 0; i-- {
fmt.Fprintf(os.Stderr, "%04d: %x\n", len(log.Stack)-i-1, common.LeftPadBytes(log.Stack[i].Bytes(), 32))
}
const maxMem = 10
addr := 0
fmt.Fprintln(os.Stderr, "MEM =", len(log.Memory))
for i := 0; i+16 <= len(log.Memory) && addr < maxMem; i += 16 {
data := log.Memory[i : i+16]
str := fmt.Sprintf("%04d: % x ", addr*16, data)
for _, r := range data {
if r == 0 {
str += "."
} else if unicode.IsPrint(rune(r)) {
str += fmt.Sprintf("%s", string(r))
} else {
str += "?"
}
}
addr++
fmt.Fprintln(os.Stderr, str)
}
fmt.Fprintln(os.Stderr, "STORAGE =", len(log.Storage))
for h, item := range log.Storage {
fmt.Fprintf(os.Stderr, "%x: %x\n", h, item)
}
fmt.Fprintln(os.Stderr)
}
}
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