Rename EroFS to Open and Opt to OpenOpt

Rename the primary API entry point from EroFS() to Open() for a cleaner,
more idiomatic Go API. Rename Opt to OpenOpt to distinguish reader
options from the upcoming Create() writer options.

The old names are preserved as deprecated type aliases and wrapper
functions for backwards compatibility, to be removed in 0.3.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Derek McGowan <derek@mcg.dev>

Author: dmcgowan

cmd/erofs-cli/main.go

@@ -30,7 +30,7 @@ func run(path string) error {
 	}
 	defer func() { _ = f.Close() }()
 
-	img, err := erofs.EroFS(f)
+	img, err := erofs.Open(f)
 	if err != nil {
 		return err
 	}

erofs.go

@@ -53,22 +53,25 @@ type options struct {
 	extraDevices []io.ReaderAt
 }
 
-// Opt is an option for configuring the EroFS reader
-type Opt func(*options)
+// OpenOpt is an option for configuring the EROFS reader
+type OpenOpt func(*options)
+
+// Deprecated: Use [OpenOpt] instead, will be removed in 0.3
+type Opt = OpenOpt
 
 // WithExtraDevices specifies additional devices to read
 // chunk data from
-func WithExtraDevices(devices ...io.ReaderAt) Opt {
+func WithExtraDevices(devices ...io.ReaderAt) OpenOpt {
 	return func(o *options) {
 		o.extraDevices = append(o.extraDevices, devices...)
 	}
 }
 
-// EroFS returns a FileSystem reading from the given readerat.
-// The readerat must be a valid erofs block file.
+// Open returns a FileSystem reading from the given ReaderAt.
+// The ReaderAt must be a valid EROFS block file.
 // No additional memory mapping is done and must be handled by
 // the caller.
-func EroFS(r io.ReaderAt, opts ...Opt) (fs.FS, error) {
+func Open(r io.ReaderAt, opts ...OpenOpt) (fs.FS, error) {
 	o := options{}
 	for _, opt := range opts {
 		opt(&o)
@@ -149,6 +152,11 @@ func EroFS(r io.ReaderAt, opts ...Opt) (fs.FS, error) {
 	return &i, nil
 }
 
+// Deprecated: Use [Open] instead, will be removed in 0.3
+func EroFS(r io.ReaderAt, opts ...Opt) (fs.FS, error) {
+	return Open(r, opts...)
+}
+
 // roundupPowerOfTwo rounds v up to the next power of two.
 func roundupPowerOfTwo(v uint32) uint32 {
 	v--

erofs_test.go

@@ -89,7 +89,7 @@ func TestErofs(t *testing.T) {
 			}
 		}()
 
-		_, err = erofs.EroFS(f)
+		_, err = erofs.Open(f)
 		if !errors.Is(err, erofs.ErrNotImplemented) {
 			t.Fatalf("expected ErrNotImplemented, got %v", err)
 		}

internal/erofstest/testcase.go

@@ -100,14 +100,14 @@ func MkfsErofsMaxSize(maxBytes int64, opts ...string) Converter {
 }
 
 // openEroFS opens an EROFS image file and returns an fs.FS.
-func openEroFS(t testing.TB, path string, opts ...erofs.Opt) fs.FS {
+func openEroFS(t testing.TB, path string, opts ...erofs.OpenOpt) fs.FS {
 	t.Helper()
 	f, err := os.Open(path)
 	if err != nil {
 		t.Fatal(err)
 	}
 	t.Cleanup(func() { _ = f.Close() })
-	efs, err := erofs.EroFS(f, opts...)
+	efs, err := erofs.Open(f, opts...)
 	if err != nil {
 		t.Fatal(err)
 	}