This closes #1075, reload temporary files into memory on save

file.go

@@ -196,6 +196,14 @@ func (f *File) writeToZip(zw *zip.Writer) error {
 		_, err = fi.Write(content.([]byte))
 		return true
 	})
-
+	f.tempFiles.Range(func(path, content interface{}) bool {
+		var fi io.Writer
+		fi, err = zw.Create(path.(string))
+		if err != nil {
+			return false
+		}
+		_, err = fi.Write(f.readBytes(path.(string)))
+		return true
+	})
 	return err
 }

file_test.go

@@ -62,6 +62,15 @@ func TestWriteTo(t *testing.T) {
 		_, err := f.WriteTo(bufio.NewWriter(&buf))
 		assert.Nil(t, err)
 	}
+	// Test write with temporary file
+	{
+		f, buf := File{tempFiles: sync.Map{}}, bytes.Buffer{}
+		const maxUint16 = 1<<16 - 1
+		f.tempFiles.Store("s", "")
+		f.tempFiles.Store(strings.Repeat("s", maxUint16+1), "")
+		_, err := f.WriteTo(bufio.NewWriter(&buf))
+		assert.EqualError(t, err, "zip: FileHeader.Name too long")
+	}
 }
 
 func TestClose(t *testing.T) {