From 0288026fdef373c1b3b7830f435be8c47b7702c0 Mon Sep 17 00:00:00 2001
From: Masaaki Goshima <goccy54@gmail.com>
Date: Thu, 18 Feb 2021 16:42:38 +0900
Subject: [PATCH] Fix decoding of invalid value

---
 decode.go                |  2 +-
 decode_test.go           |  4 ---
 decode_unmarshal_text.go | 73 ++++++++++++++++++++++++++++------------
 3 files changed, 52 insertions(+), 27 deletions(-)

diff --git a/decode.go b/decode.go
index 84ad4f0..c700579 100644
--- a/decode.go
+++ b/decode.go
@@ -78,7 +78,7 @@ func noescape(p unsafe.Pointer) unsafe.Pointer {
 }
 
 func validateType(typ *rtype, p uintptr) error {
-	if typ.Kind() != reflect.Ptr || p == 0 {
+	if typ == nil || typ.Kind() != reflect.Ptr || p == 0 {
 		return &InvalidUnmarshalError{Type: rtype2type(typ)}
 	}
 	return nil
diff --git a/decode_test.go b/decode_test.go
index 4a4a171..742143d 100644
--- a/decode_test.go
+++ b/decode_test.go
@@ -2475,7 +2475,6 @@ var invalidUnmarshalTests = []struct {
 	{(*int)(nil), "json: Unmarshal(nil *int)"},
 }
 
-/*
 func TestInvalidUnmarshal(t *testing.T) {
 	buf := []byte(`{"a":"1"}`)
 	for _, tt := range invalidUnmarshalTests {
@@ -2489,7 +2488,6 @@ func TestInvalidUnmarshal(t *testing.T) {
 		}
 	}
 }
-*/
 
 var invalidUnmarshalTextTests = []struct {
 	v    interface{}
@@ -2501,7 +2499,6 @@ var invalidUnmarshalTextTests = []struct {
 	{new(net.IP), "json: cannot unmarshal number into Go value of type *net.IP"},
 }
 
-/*
 func TestInvalidUnmarshalText(t *testing.T) {
 	buf := []byte(`123`)
 	for _, tt := range invalidUnmarshalTextTests {
@@ -2515,7 +2512,6 @@ func TestInvalidUnmarshalText(t *testing.T) {
 		}
 	}
 }
-*/
 
 /*
 // Test that string option is ignored for invalid types.
diff --git a/decode_unmarshal_text.go b/decode_unmarshal_text.go
index 1cde243..33469a4 100644
--- a/decode_unmarshal_text.go
+++ b/decode_unmarshal_text.go
@@ -44,25 +44,31 @@ func (d *unmarshalTextDecoder) decodeStream(s *stream, p unsafe.Pointer) error {
 		return err
 	}
 	src := s.buf[start:s.cursor]
-	switch src[0] {
-	case '[':
-		// cannot decode array value by unmarshal text
-		return &UnmarshalTypeError{
-			Value:  "array",
-			Type:   rtype2type(d.typ),
-			Offset: s.totalOffset(),
-		}
-	case '{':
-		// cannot decode object value by unmarshal text
-		return &UnmarshalTypeError{
-			Value:  "object",
-			Type:   rtype2type(d.typ),
-			Offset: s.totalOffset(),
-		}
-	case 'n':
-		if bytes.Equal(src, nullbytes) {
-			*(*unsafe.Pointer)(p) = nil
-			return nil
+	if len(src) > 0 {
+		switch src[0] {
+		case '[':
+			return &UnmarshalTypeError{
+				Value:  "array",
+				Type:   rtype2type(d.typ),
+				Offset: s.totalOffset(),
+			}
+		case '{':
+			return &UnmarshalTypeError{
+				Value:  "object",
+				Type:   rtype2type(d.typ),
+				Offset: s.totalOffset(),
+			}
+		case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+			return &UnmarshalTypeError{
+				Value:  "number",
+				Type:   rtype2type(d.typ),
+				Offset: s.totalOffset(),
+			}
+		case 'n':
+			if bytes.Equal(src, nullbytes) {
+				*(*unsafe.Pointer)(p) = nil
+				return nil
+			}
 		}
 	}
 	dst := make([]byte, len(src))
@@ -90,9 +96,32 @@ func (d *unmarshalTextDecoder) decode(buf []byte, cursor int64, p unsafe.Pointer
 		return 0, err
 	}
 	src := buf[start:end]
-	if bytes.Equal(src, nullbytes) {
-		*(*unsafe.Pointer)(p) = nil
-		return end, nil
+	if len(src) > 0 {
+		switch src[0] {
+		case '[':
+			return 0, &UnmarshalTypeError{
+				Value:  "array",
+				Type:   rtype2type(d.typ),
+				Offset: start,
+			}
+		case '{':
+			return 0, &UnmarshalTypeError{
+				Value:  "object",
+				Type:   rtype2type(d.typ),
+				Offset: start,
+			}
+		case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+			return 0, &UnmarshalTypeError{
+				Value:  "number",
+				Type:   rtype2type(d.typ),
+				Offset: start,
+			}
+		case 'n':
+			if bytes.Equal(src, nullbytes) {
+				*(*unsafe.Pointer)(p) = nil
+				return end, nil
+			}
+		}
 	}
 
 	if s, ok := unquoteBytes(src); ok {