From 23658550c40dd0e2680c2a16dc544c0b19e979fc Mon Sep 17 00:00:00 2001
From: FacundoMora <facundo.mora@mercadolibre.com>
Date: Wed, 1 Feb 2023 15:03:45 -0300
Subject: [PATCH] Fix binaryVarPrefixer to work with more bytes than prefix
 (#212)

---
 prefix/binary.go      |  8 +++++---
 prefix/binary_test.go | 26 ++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/prefix/binary.go b/prefix/binary.go
index 1f14f4ee..f3a71e3c 100644
--- a/prefix/binary.go
+++ b/prefix/binary.go
@@ -93,15 +93,17 @@ func (p *binaryVarPrefixer) DecodeLength(maxLen int, data []byte) (int, int, err
 		return 0, 0, fmt.Errorf("not enough data length: %d to read: %d bytes", len(data), p.Digits)
 	}
 
+	prefBytes := data[:p.Digits]
+
 	// it take 4 bytes to encode (u)int32
 	uint32Size := 4
 
 	// prepend with 0x00 if len of data is less than intSize (4 bytes)
-	if len(data) < uint32Size {
-		data = append(bytes.Repeat([]byte{0x00}, uint32Size-len(data)), data...)
+	if len(prefBytes) < uint32Size {
+		prefBytes = append(bytes.Repeat([]byte{0x00}, uint32Size-len(prefBytes)), prefBytes...)
 	}
 
-	dataLen, err := bytesToInt(data)
+	dataLen, err := bytesToInt(prefBytes)
 	if err != nil {
 		return 0, 0, fmt.Errorf("decode length: %w", err)
 	}
diff --git a/prefix/binary_test.go b/prefix/binary_test.go
index 213cca39..d8daeef4 100644
--- a/prefix/binary_test.go
+++ b/prefix/binary_test.go
@@ -152,6 +152,19 @@ func Test_binaryVarPrefixer_DecodeLength(t *testing.T) {
 			wantRead:    1,
 			wantErr:     false,
 		},
+		{
+			name: "success(L)_withMoreData",
+			fields: fields{
+				Digits: 1,
+			},
+			args: args{
+				maxLen: 32,
+				data:   []byte{0x18, 0x0, 0x0, 0x0},
+			},
+			wantDataLen: 24,
+			wantRead:    1,
+			wantErr:     false,
+		},
 		{
 			name: "success(LLL)",
 			fields: fields{
@@ -165,6 +178,19 @@ func Test_binaryVarPrefixer_DecodeLength(t *testing.T) {
 			wantRead:    3,
 			wantErr:     false,
 		},
+		{
+			name: "success(LLL)_withMoreData",
+			fields: fields{
+				Digits: 3,
+			},
+			args: args{
+				maxLen: 19999999,
+				data:   []byte{0xab, 0xcb, 0xff, 0x0, 0x0, 0x0},
+			},
+			wantDataLen: 11258879,
+			wantRead:    3,
+			wantErr:     false,
+		},
 		{
 			name: "not_enough_data",
 			fields: fields{