From dc7cd7e4b5a8bd3cf43cfecd153170d8338d08b6 Mon Sep 17 00:00:00 2001
From: Jeff Wentworth <jeff@curvegrid.com>
Date: Tue, 12 Nov 2019 20:41:41 +0900
Subject: [PATCH] fix parseTopics() and add tests

---
 accounts/abi/bind/topics.go      |  8 ++++++
 accounts/abi/bind/topics_test.go | 43 ++++++++++++++++++++++++++++++++
 accounts/abi/unpack.go           |  8 +++---
 3 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/accounts/abi/bind/topics.go b/accounts/abi/bind/topics.go
index e27fa54842..ea71a936f3 100644
--- a/accounts/abi/bind/topics.go
+++ b/accounts/abi/bind/topics.go
@@ -135,6 +135,7 @@ func parseTopics(out interface{}, fields abi.Arguments, topics []common.Hash) er
 		case reflect.Int8:
 			num := new(big.Int).SetBytes(topics[0][:])
 			field.Set(reflect.ValueOf(int8(num.Int64())))
+			fmt.Printf("parseTopics: num '%v', topics[0] '%v', field '%v'\n", num, topics[0], field)
 
 		case reflect.Int16:
 			num := new(big.Int).SetBytes(topics[0][:])
@@ -178,6 +179,13 @@ func parseTopics(out interface{}, fields abi.Arguments, topics []common.Hash) er
 
 			case reflectBigInt:
 				num := new(big.Int).SetBytes(topics[0][:])
+				if arg.Type.T == abi.IntTy {
+					if num.Cmp(abi.MaxInt256) > 0 {
+						num.Add(abi.MaxUint256, big.NewInt(0).Neg(num))
+						num.Add(num, big.NewInt(1))
+						num.Neg(num)
+					}
+				}
 				field.Set(reflect.ValueOf(num))
 
 			default:
diff --git a/accounts/abi/bind/topics_test.go b/accounts/abi/bind/topics_test.go
index f18e2d1bd2..f178574381 100644
--- a/accounts/abi/bind/topics_test.go
+++ b/accounts/abi/bind/topics_test.go
@@ -17,6 +17,7 @@
 package bind
 
 import (
+	"math/big"
 	"reflect"
 	"testing"
 
@@ -59,7 +60,15 @@ func TestParseTopics(t *testing.T) {
 	type bytesStruct struct {
 		StaticBytes [5]byte
 	}
+	type int8Struct struct {
+		Int8Value int8
+	}
+	type int256Struct struct {
+		Int256Value *big.Int
+	}
 	bytesType, _ := abi.NewType("bytes5", "", nil)
+	int8Type, _ := abi.NewType("int8", "", nil)
+	int256Type, _ := abi.NewType("int256", "", nil)
 	type args struct {
 		createObj func() interface{}
 		resultObj func() interface{}
@@ -87,6 +96,40 @@ func TestParseTopics(t *testing.T) {
 			},
 			wantErr: false,
 		},
+		{
+			name: "int8 with negative value",
+			args: args{
+				createObj: func() interface{} { return &int8Struct{} },
+				resultObj: func() interface{} { return &int8Struct{Int8Value: -1} },
+				fields: abi.Arguments{abi.Argument{
+					Name:    "int8Value",
+					Type:    int8Type,
+					Indexed: true,
+				}},
+				topics: []common.Hash{
+					{255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+						255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255},
+				},
+			},
+			wantErr: false,
+		},
+		{
+			name: "int256 with negative value",
+			args: args{
+				createObj: func() interface{} { return &int256Struct{} },
+				resultObj: func() interface{} { return &int256Struct{Int256Value: big.NewInt(-1)} },
+				fields: abi.Arguments{abi.Argument{
+					Name:    "int256Value",
+					Type:    int256Type,
+					Indexed: true,
+				}},
+				topics: []common.Hash{
+					{255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
+						255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255},
+				},
+			},
+			wantErr: false,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
diff --git a/accounts/abi/unpack.go b/accounts/abi/unpack.go
index b2e61d06c4..918905c7fb 100644
--- a/accounts/abi/unpack.go
+++ b/accounts/abi/unpack.go
@@ -26,10 +26,10 @@ import (
 )
 
 var (
-	maxUint256 = big.NewInt(0).Add(
+	MaxUint256 = big.NewInt(0).Add(
 		big.NewInt(0).Exp(big.NewInt(2), big.NewInt(256), nil),
 		big.NewInt(-1))
-	maxInt256 = big.NewInt(0).Add(
+	MaxInt256 = big.NewInt(0).Add(
 		big.NewInt(0).Exp(big.NewInt(2), big.NewInt(255), nil),
 		big.NewInt(-1))
 )
@@ -62,8 +62,8 @@ func readInteger(typ byte, kind reflect.Kind, b []byte) interface{} {
 			return ret
 		}
 
-		if ret.Cmp(maxInt256) > 0 {
-			ret.Add(maxUint256, big.NewInt(0).Neg(ret))
+		if ret.Cmp(MaxInt256) > 0 {
+			ret.Add(MaxUint256, big.NewInt(0).Neg(ret))
 			ret.Add(ret, big.NewInt(1))
 			ret.Neg(ret)
 		}