make workbook open filed exception message clear

- New exported constant `ErrWorkbookPassword`
- Rename exported constant `ErrWorkbookExt` to `ErrWorkbookFileFormat`

1 files changed, 5 insertions, 3 deletions

diff --git a/excelize.go b/excelize.go
index d78d2b1..0e2f440 100644
--- a/excelize.go
+++ b/excelize.go
@@ -158,13 +158,15 @@ func OpenReader(r io.Reader, opt ...Options) (*File, error) {
 		return nil, ErrOptionsUnzipSizeLimit
 	}
 	if bytes.Contains(b, oleIdentifier) {
-		b, err = Decrypt(b, f.options)
-		if err != nil {
-			return nil, fmt.Errorf("decrypted file failed")
+		if b, err = Decrypt(b, f.options); err != nil {
+			return nil, ErrWorkbookFileFormat
 		}
 	}
 	zr, err := zip.NewReader(bytes.NewReader(b), int64(len(b)))
 	if err != nil {
+		if len(f.options.Password) > 0 {
+			return nil, ErrWorkbookPassword
+		}
 		return nil, err
 	}
 	file, sheetCount, err := f.ReadZipReader(zr)