Revert `fillBytes` method to `bigIntToBytes` for lower golang version (#3498)

* revert fillbytes method for lower version of golang

* awww shut up dude

* use copy

* Use DEPRECATED

Co-authored-by: Will Winder <wwinder.unh@gmail.com>

Co-authored-by: Will Winder <wwinder.unh@gmail.com>

3 files changed, 41 insertions, 17 deletions

diff --git a/data/abi/abi_encode.go b/data/abi/abi_encode.go
index 8e5a49086..ac25588f0 100644
--- a/data/abi/abi_encode.go
+++ b/data/abi/abi_encode.go
@@ -25,6 +25,23 @@ import (
 	"strings"
 )
 
+// bigIntToBytes casts non-negative big integer to byte slice with specific byte length
+// DEPRECATED: THIS IS A WORKAROUND FOR `fillBytes` METHOD BEFORE GOLANG 1.15+
+//       SHOULD BE REMOVED AFTER WE MOVE TO HIGHER VERSION
+func bigIntToBytes(x *big.Int, byteLen uint) ([]byte, error) {
+	if x.Cmp(big.NewInt(0)) < 0 {
+		return nil, fmt.Errorf("ABI: big Int To Bytes error: should pass in non-negative integer")
+	}
+	if uint(x.BitLen()) > byteLen*8 {
+		return nil, fmt.Errorf("ABI: big Int To Bytes error: integer byte length > given byte length")
+	}
+
+	buffer := make([]byte, byteLen)
+	intBytes := x.Bytes()
+	copy(buffer[int(byteLen)-len(intBytes):], intBytes)
+	return buffer, nil
+}
+
 // typeCastToTuple cast an array-like ABI type into an ABI tuple type.
 func (t Type) typeCastToTuple(tupLen ...int) (Type, error) {
 	var childT []Type
@@ -170,13 +187,14 @@ func encodeInt(intValue interface{}, bitSize uint16) ([]byte, error) {
 		return nil, fmt.Errorf("passed in numeric value should be non negative")
 	}
 
-	castedBytes := make([]byte, bitSize/8)
-
 	if bigInt.Cmp(new(big.Int).Lsh(big.NewInt(1), uint(bitSize))) >= 0 {
 		return nil, fmt.Errorf("input value bit size %d > abi type bit size %d", bigInt.BitLen(), bitSize)
 	}
 
-	bigInt.FillBytes(castedBytes)
+	castedBytes, err := bigIntToBytes(bigInt, uint(bitSize/8))
+	if err != nil {
+		return nil, err
+	}
 	return castedBytes, nil
 }
 
diff --git a/data/abi/abi_encode_test.go b/data/abi/abi_encode_test.go
index 66060f5ce..620013c23 100644
--- a/data/abi/abi_encode_test.go
+++ b/data/abi/abi_encode_test.go
@@ -83,8 +83,8 @@ func TestEncodeValid(t *testing.T) {
 			randomInt, err := rand.Int(rand.Reader, upperLimit)
 			require.NoError(t, err, "cryptographic random int init fail")
 
-			expected := make([]byte, intSize/8)
-			randomInt.FillBytes(expected)
+			expected, err := bigIntToBytes(randomInt, uint(intSize/8))
+			require.NoError(t, err, "big int to byte conversion error")
 
 			uintEncode, err := uintType.Encode(randomInt)
 			require.NoError(t, err, "encoding from uint type fail")
@@ -122,8 +122,9 @@ func TestEncodeValid(t *testing.T) {
 				encodedUfixed, err := typeUfixed.Encode(randomInt)
 				require.NoError(t, err, "ufixed encode fail")
 
-				expected := make([]byte, size/8)
-				randomInt.FillBytes(expected)
+				expected, err := bigIntToBytes(randomInt, uint(size/8))
+				require.NoError(t, err, "big int to byte conversion error")
+
 				require.Equal(t, expected, encodedUfixed, "encode ufixed not match with expected")
 			}
 			// (2^[bitSize] - 1) / (10^[precision]) test
@@ -141,8 +142,8 @@ func TestEncodeValid(t *testing.T) {
 		randomAddrInt, err := rand.Int(rand.Reader, upperLimit)
 		require.NoError(t, err, "cryptographic random int init fail")
 
-		addrBytesExpected := make([]byte, addressByteSize)
-		randomAddrInt.FillBytes(addrBytesExpected)
+		addrBytesExpected, err := bigIntToBytes(randomAddrInt, uint(addressByteSize))
+		require.NoError(t, err, "big int to byte conversion error")
 
 		addrBytesActual, err := addressType.Encode(addrBytesExpected)
 		require.NoError(t, err, "address encode fail")
@@ -421,8 +422,8 @@ func TestDecodeValid(t *testing.T) {
 		randomAddrInt, err := rand.Int(rand.Reader, upperLimit)
 		require.NoError(t, err, "cryptographic random int init fail")
 
-		expected := make([]byte, addressByteSize)
-		randomAddrInt.FillBytes(expected)
+		expected, err := bigIntToBytes(randomAddrInt, uint(addressByteSize))
+		require.NoError(t, err, "big int to byte conversion error")
 
 		actual, err := addressType.Decode(expected)
 		require.NoError(t, err, "decoding address should not return error")
@@ -951,8 +952,10 @@ func addPrimitiveRandomValues(t *testing.T, pool *map[BaseType][]testUnit) {
 	for i := 0; i < addressTestCaseCount; i++ {
 		randAddrVal, err := rand.Int(rand.Reader, maxAddress)
 		require.NoError(t, err, "generate random value for address, should be no error")
-		addrBytes := make([]byte, addressByteSize)
-		randAddrVal.FillBytes(addrBytes)
+
+		addrBytes, err := bigIntToBytes(randAddrVal, uint(addressByteSize))
+		require.NoError(t, err, "big int to byte conversion error")
+
 		(*pool)[Address][i] = testUnit{serializedType: addressType.String(), value: addrBytes}
 	}
 	categorySelfRoundTripTest(t, (*pool)[Address])
@@ -1162,7 +1165,7 @@ func TestParseArgJSONtoByteSlice(t *testing.T) {
 
 	for i, test := range tests {
 		t.Run(fmt.Sprintf("index=%d", i), func(t *testing.T) {
-			applicationArgs := [][]byte{}
+			applicationArgs := make([][]byte, 0)
 			err := ParseArgJSONtoByteSlice(test.argTypes, test.jsonArgs, &applicationArgs)
 			require.NoError(t, err)
 			require.Equal(t, test.expectedAppArgs, applicationArgs)
diff --git a/data/abi/abi_json_test.go b/data/abi/abi_json_test.go
index 49083fdea..0c3a006e3 100644
--- a/data/abi/abi_json_test.go
+++ b/data/abi/abi_json_test.go
@@ -31,14 +31,17 @@ func TestRandomAddressEquality(t *testing.T) {
 
 	upperLimit := new(big.Int).Lsh(big.NewInt(1), addressByteSize<<3)
 	var addrBasics basics.Address
-	var addrABI []byte = make([]byte, addressByteSize)
+	var addrABI = make([]byte, addressByteSize)
 
 	for testCaseIndex := 0; testCaseIndex < addressTestCaseCount; testCaseIndex++ {
 		randomAddrInt, err := rand.Int(rand.Reader, upperLimit)
 		require.NoError(t, err, "cryptographic random int init fail")
 
-		randomAddrInt.FillBytes(addrBasics[:])
-		randomAddrInt.FillBytes(addrABI)
+		expected, err := bigIntToBytes(randomAddrInt, uint(addressByteSize))
+		require.NoError(t, err, "big int to byte conversion error")
+
+		copy(addrABI[:], expected)
+		copy(addrBasics[:], expected)
 
 		checkSumBasics := addrBasics.GetChecksum()
 		checkSumABI, err := addressCheckSum(addrABI)