From 286ec5df40d3707a7a2c98d49c8d324372ed29c2 Mon Sep 17 00:00:00 2001
From: Martin Holst Swende <martin@swende.se>
Date: Wed, 23 Aug 2017 13:37:18 +0200
Subject: [PATCH] cmd/evm, core/vm, internal/ethapi: Show error when exiting
 (#14985)

* cmd/evm, core/vm, internal/ethapi: Add 'err' to tracer interface CaptureEnd

* cmd/evm: fix nullpointer when there is no error
---
 cmd/evm/json_logger.go    | 8 ++++++--
 cmd/evm/runner.go         | 8 ++++----
 core/vm/logger.go         | 7 +++++--
 internal/ethapi/tracer.go | 2 +-
 4 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/cmd/evm/json_logger.go b/cmd/evm/json_logger.go
index d61981062c..2cfeaa7952 100644
--- a/cmd/evm/json_logger.go
+++ b/cmd/evm/json_logger.go
@@ -57,11 +57,15 @@ func (l *JSONLogger) CaptureState(env *vm.EVM, pc uint64, op vm.OpCode, gas, cos
 }
 
 // CaptureEnd is triggered at end of execution.
-func (l *JSONLogger) CaptureEnd(output []byte, gasUsed uint64, t time.Duration) error {
+func (l *JSONLogger) CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) error {
 	type endLog struct {
 		Output  string              `json:"output"`
 		GasUsed math.HexOrDecimal64 `json:"gasUsed"`
 		Time    time.Duration       `json:"time"`
+		Err     string              `json:"error,omitempty"`
 	}
-	return l.encoder.Encode(endLog{common.Bytes2Hex(output), math.HexOrDecimal64(gasUsed), t})
+	if err != nil {
+		return l.encoder.Encode(endLog{common.Bytes2Hex(output), math.HexOrDecimal64(gasUsed), t, err.Error()})
+	}
+	return l.encoder.Encode(endLog{common.Bytes2Hex(output), math.HexOrDecimal64(gasUsed), t, ""})
 }
diff --git a/cmd/evm/runner.go b/cmd/evm/runner.go
index ae56781103..96de0c76ac 100644
--- a/cmd/evm/runner.go
+++ b/cmd/evm/runner.go
@@ -234,13 +234,13 @@ Gas used:           %d
 `, execTime, mem.HeapObjects, mem.Alloc, mem.TotalAlloc, mem.NumGC, initialGas-leftOverGas)
 	}
 	if tracer != nil {
-		tracer.CaptureEnd(ret, initialGas-leftOverGas, execTime)
+		tracer.CaptureEnd(ret, initialGas-leftOverGas, execTime, err)
 	} else {
 		fmt.Printf("0x%x\n", ret)
+		if err != nil {
+			fmt.Printf(" error: %v\n", err)
+		}
 	}
 
-	if err != nil {
-		fmt.Printf(" error: %v\n", err)
-	}
 	return nil
 }
diff --git a/core/vm/logger.go b/core/vm/logger.go
index b73b13bd97..5ada310f0a 100644
--- a/core/vm/logger.go
+++ b/core/vm/logger.go
@@ -86,7 +86,7 @@ func (s *StructLog) OpName() string {
 // if you need to retain them beyond the current call.
 type Tracer interface {
 	CaptureState(env *EVM, pc uint64, op OpCode, gas, cost uint64, memory *Memory, stack *Stack, contract *Contract, depth int, err error) error
-	CaptureEnd(output []byte, gasUsed uint64, t time.Duration) error
+	CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) error
 }
 
 // StructLogger is an EVM state logger and implements Tracer.
@@ -183,8 +183,11 @@ func (l *StructLogger) CaptureState(env *EVM, pc uint64, op OpCode, gas, cost ui
 	return nil
 }
 
-func (l *StructLogger) CaptureEnd(output []byte, gasUsed uint64, t time.Duration) error {
+func (l *StructLogger) CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) error {
 	fmt.Printf("0x%x", output)
+	if err != nil {
+		fmt.Printf(" error: %v\n", err)
+	}
 	return nil
 }
 
diff --git a/internal/ethapi/tracer.go b/internal/ethapi/tracer.go
index fc66839ea5..0516265270 100644
--- a/internal/ethapi/tracer.go
+++ b/internal/ethapi/tracer.go
@@ -346,7 +346,7 @@ func (jst *JavascriptTracer) CaptureState(env *vm.EVM, pc uint64, op vm.OpCode,
 }
 
 // CaptureEnd is called after the call finishes
-func (jst *JavascriptTracer) CaptureEnd(output []byte, gasUsed uint64, t time.Duration) error {
+func (jst *JavascriptTracer) CaptureEnd(output []byte, gasUsed uint64, t time.Duration, err error) error {
 	//TODO! @Arachnid please figure out of there's anything we can use this method for
 	return nil
 }