Official Go implementation of the Ethereum protocol
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go-ethereum/eth/tracers/native/call.go

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// Copyright 2021 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 native
import (
"encoding/json"
"errors"
"math/big"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/core/vm"
"github.com/ethereum/go-ethereum/eth/tracers"
)
//go:generate go run github.com/fjl/gencodec -type callFrame -field-override callFrameMarshaling -out gen_callframe_json.go
func init() {
register("callTracer", newCallTracer)
}
type callFrame struct {
Type vm.OpCode `json:"-"`
From common.Address `json:"from"`
Gas uint64 `json:"gas"`
GasUsed uint64 `json:"gasUsed"`
To common.Address `json:"to,omitempty" rlp:"optional"`
Input []byte `json:"input" rlp:"optional"`
Output []byte `json:"output,omitempty" rlp:"optional"`
Error string `json:"error,omitempty" rlp:"optional"`
Calls []callFrame `json:"calls,omitempty" rlp:"optional"`
// Placed at end on purpose. The RLP will be decoded to 0 instead of
// nil if there are non-empty elements after in the struct.
Value *big.Int `json:"value,omitempty" rlp:"optional"`
}
func (f callFrame) TypeString() string {
return f.Type.String()
}
type callFrameMarshaling struct {
TypeString string `json:"type"`
Gas hexutil.Uint64
GasUsed hexutil.Uint64
Value *hexutil.Big
Input hexutil.Bytes
Output hexutil.Bytes
}
type callTracer struct {
env *vm.EVM
callstack []callFrame
config callTracerConfig
interrupt uint32 // Atomic flag to signal execution interruption
reason error // Textual reason for the interruption
}
type callTracerConfig struct {
OnlyTopCall bool `json:"onlyTopCall"` // If true, call tracer won't collect any subcalls
}
// newCallTracer returns a native go tracer which tracks
// call frames of a tx, and implements vm.EVMLogger.
func newCallTracer(ctx *tracers.Context, cfg json.RawMessage) (tracers.Tracer, error) {
var config callTracerConfig
if cfg != nil {
if err := json.Unmarshal(cfg, &config); err != nil {
return nil, err
}
}
// First callframe contains tx context info
// and is populated on start and end.
return &callTracer{callstack: make([]callFrame, 1), config: config}, nil
}
// CaptureStart implements the EVMLogger interface to initialize the tracing operation.
func (t *callTracer) CaptureStart(env *vm.EVM, from common.Address, to common.Address, create bool, input []byte, gas uint64, value *big.Int) {
t.env = env
t.callstack[0] = callFrame{
Type: vm.CALL,
From: from,
To: to,
Input: common.CopyBytes(input),
Gas: gas,
Value: value,
}
if create {
t.callstack[0].Type = vm.CREATE
}
}
// CaptureEnd is called after the call finishes to finalize the tracing.
func (t *callTracer) CaptureEnd(output []byte, gasUsed uint64, _ time.Duration, err error) {
t.callstack[0].GasUsed = gasUsed
output = common.CopyBytes(output)
if err != nil {
t.callstack[0].Error = err.Error()
if err.Error() == "execution reverted" && len(output) > 0 {
t.callstack[0].Output = output
}
} else {
t.callstack[0].Output = output
}
}
// CaptureState implements the EVMLogger interface to trace a single step of VM execution.
func (t *callTracer) CaptureState(pc uint64, op vm.OpCode, gas, cost uint64, scope *vm.ScopeContext, rData []byte, depth int, err error) {
}
// CaptureFault implements the EVMLogger interface to trace an execution fault.
func (t *callTracer) CaptureFault(pc uint64, op vm.OpCode, gas, cost uint64, _ *vm.ScopeContext, depth int, err error) {
}
// CaptureEnter is called when EVM enters a new scope (via call, create or selfdestruct).
func (t *callTracer) CaptureEnter(typ vm.OpCode, from common.Address, to common.Address, input []byte, gas uint64, value *big.Int) {
if t.config.OnlyTopCall {
return
}
// Skip if tracing was interrupted
if atomic.LoadUint32(&t.interrupt) > 0 {
t.env.Cancel()
return
}
call := callFrame{
Type: typ,
From: from,
To: to,
Input: common.CopyBytes(input),
Gas: gas,
Value: value,
}
t.callstack = append(t.callstack, call)
}
// CaptureExit is called when EVM exits a scope, even if the scope didn't
// execute any code.
func (t *callTracer) CaptureExit(output []byte, gasUsed uint64, err error) {
if t.config.OnlyTopCall {
return
}
size := len(t.callstack)
if size <= 1 {
return
}
// pop call
call := t.callstack[size-1]
t.callstack = t.callstack[:size-1]
size -= 1
call.GasUsed = gasUsed
if err == nil {
call.Output = common.CopyBytes(output)
} else {
call.Error = err.Error()
if call.Type == vm.CREATE || call.Type == vm.CREATE2 {
call.To = common.Address{}
}
}
t.callstack[size-1].Calls = append(t.callstack[size-1].Calls, call)
}
func (*callTracer) CaptureTxStart(gasLimit uint64) {}
func (*callTracer) CaptureTxEnd(restGas uint64) {}
// GetResult returns the json-encoded nested list of call traces, and any
// error arising from the encoding or forceful termination (via `Stop`).
func (t *callTracer) GetResult() (json.RawMessage, error) {
if len(t.callstack) != 1 {
return nil, errors.New("incorrect number of top-level calls")
}
res, err := json.Marshal(t.callstack[0])
if err != nil {
return nil, err
}
return json.RawMessage(res), t.reason
}
// Stop terminates execution of the tracer at the first opportune moment.
func (t *callTracer) Stop(err error) {
t.reason = err
atomic.StoreUint32(&t.interrupt, 1)
}