encoding/binary: document that Read returns io.EOF iff zero bytes are read
Also add a unit test to lock this behavior into the API.
Fixes #12016
Change-Id: Ib6ec6e7948f0705f3504ede9143b5dc4e790fc44
Reviewed-on: https://go-review.googlesource.com/15171
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/encoding/binary/binary.go b/src/encoding/binary/binary.go
index 2bbe07c..1c2577b 100644
--- a/src/encoding/binary/binary.go
+++ b/src/encoding/binary/binary.go
@@ -135,6 +135,10 @@
// blank (_) field names is skipped; i.e., blank field names
// may be used for padding.
// When reading into a struct, all non-blank fields must be exported.
+//
+// The error is EOF only if no bytes were read.
+// If an EOF happens after reading some but not all the bytes,
+// Read returns ErrUnexpectedEOF.
func Read(r io.Reader, order ByteOrder, data interface{}) error {
// Fast path for basic types and slices.
if n := intDataSize(data); n != 0 {
diff --git a/src/encoding/binary/binary_test.go b/src/encoding/binary/binary_test.go
index 8ee595f..7fd36fa 100644
--- a/src/encoding/binary/binary_test.go
+++ b/src/encoding/binary/binary_test.go
@@ -309,6 +309,36 @@
read(&p)
}
+func TestReadTruncated(t *testing.T) {
+ const data = "0123456789abcdef"
+
+ var b1 = make([]int32, 4)
+ var b2 struct {
+ A, B, C, D byte
+ E int32
+ F float64
+ }
+
+ for i := 0; i <= len(data); i++ {
+ var errWant error
+ switch i {
+ case 0:
+ errWant = io.EOF
+ case len(data):
+ errWant = nil
+ default:
+ errWant = io.ErrUnexpectedEOF
+ }
+
+ if err := Read(strings.NewReader(data[:i]), LittleEndian, &b1); err != errWant {
+ t.Errorf("Read(%d) with slice: got %v, want %v", i, err, errWant)
+ }
+ if err := Read(strings.NewReader(data[:i]), LittleEndian, &b2); err != errWant {
+ t.Errorf("Read(%d) with struct: got %v, want %v", i, err, errWant)
+ }
+ }
+}
+
type byteSliceReader struct {
remain []byte
}
