set File size to 0 if not a stream

file.go

@@ -116,6 +116,9 @@ func (r *Reader) setDirEntries() error {
 
 func fixFile(v uint16, f *File) {
 	fixName(f)
+	if f.objectType != stream {
+		return
+	}
 	// if the MSCFB major version is 4, then this can be a uint64 otherwise is a uint32 and the least signficant bits can contain junk
 	if v > 3 {
 		f.Size = int64(binary.LittleEndian.Uint64(f.streamSize[:]))
@@ -232,7 +235,7 @@ func (f *File) Modified() time.Time {
 // Read this directory entry
 // Returns 0, io.EOF if no stream is available (i.e. for a storage object)
 func (f *File) Read(b []byte) (int, error) {
-	if f.objectType != stream || f.Size < 1 || f.i >= f.Size {
+	if f.Size < 1 || f.i >= f.Size {
 		return 0, io.EOF
 	}
 	sz := len(b)
@@ -272,7 +275,7 @@ func (f *File) Read(b []byte) (int, error) {
 // Depends on the io.ReaderAt supplied to mscfb.New() being a WriterAt too
 // Returns 0, io.EOF if no stream is available (i.e. for a storage object)
 func (f *File) Write(b []byte) (int, error) {
-	if f.objectType != stream || f.Size < 1 || f.i >= f.Size {
+	if f.Size < 1 || f.i >= f.Size {
 		return 0, io.EOF
 	}
 	if f.r.wa == nil {

mscfb_test.go

@@ -143,6 +143,21 @@ func TestXls(t *testing.T) {
 	testFile(t, testXls)
 }
 
+func TestSeek(t *testing.T) {
+	file, _ := os.Open(testXls)
+	defer file.Close()
+	doc, _ := New(file)
+	// the first entry in the XLS file is 2719 bytes
+	if doc.File[3].Size != 2719 {
+		t.Fatalf("Expecting the third entry of the XLS file to be 2719 bytes long; it is %d", doc.File[3].Size)
+	}
+	buf := make([]byte, 2719)
+	i, err := doc.File[3].Read(buf)
+	if i != 2719 || err != nil {
+		t.Fatalf("Expecting 2719 length and an EOF; got %d and %v", i, err)
+	}
+}
+
 func TestWrite(t *testing.T) {
 	file, err := os.OpenFile(testXls, os.O_RDWR, 0666)
 	if err != nil {