make workbook open filed exception message clear

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

crypt_test.go

@@ -19,6 +19,9 @@ import (
 )
 
 func TestEncrypt(t *testing.T) {
+	_, err := OpenFile(filepath.Join("test", "encryptSHA1.xlsx"), Options{Password: "passwd"})
+	assert.EqualError(t, err, ErrWorkbookPassword.Error())
+
 	f, err := OpenFile(filepath.Join("test", "encryptSHA1.xlsx"), Options{Password: "password"})
 	assert.NoError(t, err)
 	assert.EqualError(t, f.SaveAs(filepath.Join("test", "BadEncrypt.xlsx"), Options{Password: "password"}), ErrEncrypt.Error())

errors.go

@@ -106,9 +106,9 @@ var (
 	// ErrImgExt defined the error message on receive an unsupported image
 	// extension.
 	ErrImgExt = errors.New("unsupported image extension")
-	// ErrWorkbookExt defined the error message on receive an unsupported
+	// ErrWorkbookFileFormat defined the error message on receive an
-	// workbook extension.
+	// unsupported workbook file format.
-	ErrWorkbookExt = errors.New("unsupported workbook extension")
+	ErrWorkbookFileFormat = errors.New("unsupported workbook file format")
 	// ErrMaxFilePathLength defined the error message on receive the file path
 	// length overflow.
 	ErrMaxFilePathLength = errors.New("file path length exceeds maximum limit")
@@ -191,4 +191,7 @@ var (
 	// ErrSparklineStyle defined the error message on receive the invalid
 	// sparkline Style parameters.
 	ErrSparklineStyle = errors.New("parameter 'Style' must between 0-35")
+	// ErrWorkbookPassword defined the error message on receiving the incorrect
+	// workbook password.
+	ErrWorkbookPassword = errors.New("the supplied open workbook password is not correct")
 )

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 b, err = Decrypt(b, f.options); err != nil {
-		if err != nil {
+			return nil, ErrWorkbookFileFormat
-			return nil, fmt.Errorf("decrypted file failed")
 		}
 	}
 	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)

excelize_test.go

@@ -1,6 +1,7 @@
 package excelize
 
 import (
+	"archive/zip"
 	"bytes"
 	"compress/gzip"
 	"encoding/xml"
@@ -179,7 +180,7 @@ func TestSaveFile(t *testing.T) {
 	if !assert.NoError(t, err) {
 		t.FailNow()
 	}
-	assert.EqualError(t, f.SaveAs(filepath.Join("test", "TestSaveFile.xlsb")), ErrWorkbookExt.Error())
+	assert.EqualError(t, f.SaveAs(filepath.Join("test", "TestSaveFile.xlsb")), ErrWorkbookFileFormat.Error())
 	for _, ext := range []string{".xlam", ".xlsm", ".xlsx", ".xltm", ".xltx"} {
 		assert.NoError(t, f.SaveAs(filepath.Join("test", fmt.Sprintf("TestSaveFile%s", ext))))
 	}
@@ -207,9 +208,9 @@ func TestCharsetTranscoder(t *testing.T) {
 
 func TestOpenReader(t *testing.T) {
 	_, err := OpenReader(strings.NewReader(""))
-	assert.EqualError(t, err, "zip: not a valid zip file")
+	assert.EqualError(t, err, zip.ErrFormat.Error())
 	_, err = OpenReader(bytes.NewReader(oleIdentifier), Options{Password: "password", UnzipXMLSizeLimit: UnzipSizeLimit + 1})
-	assert.EqualError(t, err, "decrypted file failed")
+	assert.EqualError(t, err, ErrWorkbookFileFormat.Error())
 
 	// Test open spreadsheet with unzip size limit.
 	_, err = OpenFile(filepath.Join("test", "Book1.xlsx"), Options{UnzipSizeLimit: 100})
@@ -261,7 +262,7 @@ func TestOpenReader(t *testing.T) {
 		0x05, 0x06, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x41, 0x00, 0x00, 0x00, 0x5d, 0x00,
 		0x00, 0x00, 0x00, 0x00,
 	}))
-	assert.EqualError(t, err, "zip: unsupported compression algorithm")
+	assert.EqualError(t, err, zip.ErrAlgorithm.Error())
 }
 
 func TestBrokenFile(t *testing.T) {

file.go

@@ -78,7 +78,7 @@ func (f *File) SaveAs(name string, opt ...Options) error {
 		".xltx": ContentTypeTemplate,
 	}[filepath.Ext(f.Path)]
 	if !ok {
-		return ErrWorkbookExt
+		return ErrWorkbookFileFormat
 	}
 	f.setContentTypePartProjectExtensions(contentType)
 	file, err := os.OpenFile(filepath.Clean(name), os.O_WRONLY|os.O_TRUNC|os.O_CREATE, os.ModePerm)