6 files changed, 52 insertions, 7 deletions
diff --git a/libgo/go/encoding/binary/varint.go b/libgo/go/encoding/binary/varint.go
index b756afdd040..719018b6033 100644
--- a/libgo/go/encoding/binary/varint.go
+++ b/libgo/go/encoding/binary/varint.go
@@ -123,7 +123,7 @@ func ReadUvarint(r io.ByteReader) (uint64, error) {
 	panic("unreachable")
 }
 
-// ReadVarint reads an encoded unsigned integer from r and returns it as a uint64.
+// ReadVarint reads an encoded unsigned integer from r and returns it as an int64.
 func ReadVarint(r io.ByteReader) (int64, error) {
 	ux, err := ReadUvarint(r) // ok to continue in presence of error
 	x := int64(ux >> 1)
diff --git a/libgo/go/encoding/gob/decode.go b/libgo/go/encoding/gob/decode.go
index e32a178aba3..8690b35d714 100644
--- a/libgo/go/encoding/gob/decode.go
+++ b/libgo/go/encoding/gob/decode.go
@@ -562,6 +562,9 @@ func (dec *Decoder) ignoreSingle(engine *decEngine) {
 func (dec *Decoder) decodeArrayHelper(state *decoderState, p uintptr, elemOp decOp, elemWid uintptr, length, elemIndir int, ovfl error) {
 	instr := &decInstr{elemOp, 0, elemIndir, 0, ovfl}
 	for i := 0; i < length; i++ {
+		if state.b.Len() == 0 {
+			errorf("decoding array or slice: length exceeds input size (%d elements)", length)
+		}
 		up := unsafe.Pointer(p)
 		if elemIndir > 1 {
 			up = decIndirect(up, elemIndir)
@@ -652,9 +655,6 @@ func (dec *Decoder) ignoreMap(state *decoderState, keyOp, elemOp decOp) {
 // Slices are encoded as an unsigned length followed by the elements.
 func (dec *Decoder) decodeSlice(atyp reflect.Type, state *decoderState, p uintptr, elemOp decOp, elemWid uintptr, indir, elemIndir int, ovfl error) {
 	nr := state.decodeUint()
-	if nr > uint64(state.b.Len()) {
-		errorf("length of slice exceeds input size (%d elements)", nr)
-	}
 	n := int(nr)
 	if indir > 0 {
 		up := unsafe.Pointer(p)
diff --git a/libgo/go/encoding/gob/doc.go b/libgo/go/encoding/gob/doc.go
index 821d9a3fe8e..6d77c171f41 100644
--- a/libgo/go/encoding/gob/doc.go
+++ b/libgo/go/encoding/gob/doc.go
@@ -118,7 +118,7 @@ elements using the standard gob encoding for their type, recursively.
 
 Maps are sent as an unsigned count followed by that many key, element
 pairs. Empty but non-nil maps are sent, so if the sender has allocated
-a map, the receiver will allocate a map even no elements are
+a map, the receiver will allocate a map even if no elements are
 transmitted.
 
 Structs are sent as a sequence of (field number, field value) pairs.  The field
diff --git a/libgo/go/encoding/gob/encoder_test.go b/libgo/go/encoding/gob/encoder_test.go
index c4947cbb8d3..db824d99917 100644
--- a/libgo/go/encoding/gob/encoder_test.go
+++ b/libgo/go/encoding/gob/encoder_test.go
@@ -736,3 +736,32 @@ func TestPtrToMapOfMap(t *testing.T) {
 		t.Fatalf("expected %v got %v", data, newData)
 	}
 }
+
+// There was an error check comparing the length of the input with the
+// length of the slice being decoded. It was wrong because the next
+// thing in the input might be a type definition, which would lead to
+// an incorrect length check.  This test reproduces the corner case.
+
+type Z struct {
+}
+
+func Test29ElementSlice(t *testing.T) {
+	Register(Z{})
+	src := make([]interface{}, 100) // Size needs to be bigger than size of type definition.
+	for i := range src {
+		src[i] = Z{}
+	}
+	buf := new(bytes.Buffer)
+	err := NewEncoder(buf).Encode(src)
+	if err != nil {
+		t.Fatalf("encode: %v", err)
+		return
+	}
+
+	var dst []interface{}
+	err = NewDecoder(buf).Decode(&dst)
+	if err != nil {
+		t.Errorf("decode: %v", err)
+		return
+	}
+}
diff --git a/libgo/go/encoding/gob/type.go b/libgo/go/encoding/gob/type.go
index 0dd7a0a770e..a8ee2fa4a5a 100644
--- a/libgo/go/encoding/gob/type.go
+++ b/libgo/go/encoding/gob/type.go
@@ -749,12 +749,28 @@ func Register(value interface{}) {
 	rt := reflect.TypeOf(value)
 	name := rt.String()
 
-	// But for named types (or pointers to them), qualify with import path.
+	// But for named types (or pointers to them), qualify with import path (but see inner comment).
 	// Dereference one pointer looking for a named type.
 	star := ""
 	if rt.Name() == "" {
 		if pt := rt; pt.Kind() == reflect.Ptr {
 			star = "*"
+			// NOTE: The following line should be rt = pt.Elem() to implement
+			// what the comment above claims, but fixing it would break compatibility
+			// with existing gobs.
+			//
+			// Given package p imported as "full/p" with these definitions:
+			//     package p
+			//     type T1 struct { ... }
+			// this table shows the intended and actual strings used by gob to
+			// name the types:
+			//
+			// Type      Correct string     Actual string
+			//
+			// T1        full/p.T1          full/p.T1
+			// *T1       *full/p.T1         *p.T1
+			//
+			// The missing full path cannot be fixed without breaking existing gob decoders.
 			rt = pt
 		}
 	}
diff --git a/libgo/go/encoding/json/encode.go b/libgo/go/encoding/json/encode.go
index b6e1cb16e5a..d2c1c4424c7 100644
--- a/libgo/go/encoding/json/encode.go
+++ b/libgo/go/encoding/json/encode.go
@@ -55,7 +55,7 @@ import (
 // nil pointer or interface value, and any array, slice, map, or string of
 // length zero. The object's default key string is the struct field name
 // but can be specified in the struct field's tag value. The "json" key in
-// struct field's tag value is the key name, followed by an optional comma
+// the struct field's tag value is the key name, followed by an optional comma
 // and options. Examples:
 //
 //   // Field is ignored by this package.