From 94ccf711744877533fe0fa5117c1761085dbe36a Mon Sep 17 00:00:00 2001
From: Aleksey Boyko <a.boyko@semrush.com>
Date: Fri, 23 Mar 2018 18:55:23 +0300
Subject: [PATCH] [encoder] fix zero len array decoding

- strings.Split with empty slice argument returns slice with 1 element
which is empty string. without check len decoder crashes on empty
numeric arrays
- encoder test added
- types test added
---
 encoder.go      | 9 +++++++--
 encoder_test.go | 2 ++
 types_test.go   | 1 +
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/encoder.go b/encoder.go
index 01764fe..bc54f42 100644
--- a/encoder.go
+++ b/encoder.go
@@ -134,8 +134,13 @@ func (d *textDecoder) Decode(t string, value []byte) (driver.Value, error) {
 		return unescape(unquote(v)), nil
 	}
 	if strings.HasPrefix(t, "Array") {
-		if len(v) > 0 && v[0] == '[' && v[len(value)-1] == ']' {
-			items := strings.Split(v[1:len(value)-1], ",")
+		if len(v) > 0 && v[0] == '[' && v[len(v)-1] == ']' {
+			var items []string
+			// check that array is not empty ([])
+			if len(v) > 2 {
+				items = strings.Split(v[1:len(v)-1], ",")
+			}
+
 			subType := t[6 : len(t)-1]
 			r := reflect.MakeSlice(reflect.SliceOf(columnType(subType)), len(items), len(items))
 			for i, item := range items {
diff --git a/encoder_test.go b/encoder_test.go
index d05d984..a92947d 100644
--- a/encoder_test.go
+++ b/encoder_test.go
@@ -34,6 +34,7 @@ func TestTextEncoder(t *testing.T) {
 		{`\\'hello`, `'\\\\\'hello'`},
 		{[]byte(`\\'hello`), `\\'hello`},
 		{[]int32{1, 2}, "[1,2]"},
+		{[]int32{}, "[]"},
 		{&d, "'2012-05-31 00:00:00'"},
 	}
 
@@ -70,6 +71,7 @@ func TestTextDecoder(t *testing.T) {
 		{"Enum8('one'=1)", "'one'", "one"},
 		{"Enum16('one'=1)", "'one'", "one"},
 		{"Array(UInt32)", "[1,2]", []uint32{1, 2}},
+		{"Array(UInt32)", "[]", []uint32{}},
 	}
 
 	dec := &textDecoder{location: time.UTC}
diff --git a/types_test.go b/types_test.go
index 9257e7a..e640f78 100644
--- a/types_test.go
+++ b/types_test.go
@@ -19,6 +19,7 @@ func TestArray(t *testing.T) {
 		{[]uint16{1, 2}, []byte("[1,2]")},
 		{[]uint32{1, 2}, []byte("[1,2]")},
 		{[]uint64{1, 2}, []byte("[1,2]")},
+		{[]uint64{}, []byte("[]")},
 	}
 
 	for _, tc := range testCases {