streamdata: metadata load helper

This loads metadata by ident.

Signed-off-by: Yonah <contrib@gensokyo.uk>

streamdata.go

@@ -197,3 +197,21 @@ func (c *Channel) Add(ident *Ident, f func(v *VOD, w io.Writer) error) error {
 
 	return nil
 }
+
+// Load loads the metadata of a [VOD] by [Ident] and returns its address.
+func (c *Channel) Load(ident *Ident) (*VOD, error) {
+	var v VOD
+	if r, err := c.root.Open(path.Join(
+		channelPathVOD,
+		ident.String(),
+	)); err != nil {
+		return nil, err
+	} else if err = json.NewDecoder(r).Decode(&v); err != nil {
+		_ = r.Close()
+		return nil, err
+	} else if err = r.Close(); err != nil {
+		return nil, err
+	} else {
+		return &v, nil
+	}
+}

streamdata_test.go

@@ -265,7 +265,7 @@ func TestChannelAdd(t *testing.T) {
 		Date:     time.Unix(0, 0).UTC(),
 		Category: "\t",
 	}
-	if err := c.Add(&streamdata.Ident{
+	ident := streamdata.Ident{
 		Serial:  0xfdfdfdfd,
 		Channel: 0xcafe,
 		Data: [streamdata.IdentFFLen]byte{
@@ -275,7 +275,8 @@ func TestChannelAdd(t *testing.T) {
 			0xf0, 0x0d,
 			0, 0, 0, 0, 0, 0,
 		},
-	}, func(v *streamdata.VOD, w io.Writer) error {
+	}
+	if err := c.Add(&ident, func(v *streamdata.VOD, w io.Writer) error {
 		*v = wantVOD
 		_, err := w.Write(wantData)
 		return err
@@ -300,11 +301,50 @@ func TestChannelAdd(t *testing.T) {
 		t.Errorf("Add: %#v, want %#v", got, wantVOD)
 	}
 
+	if gotVOD, err := c.Load(&ident); err != nil {
+		t.Fatalf("Load: error = %v", err)
+	} else if *gotVOD != wantVOD {
+		t.Errorf("Load: %#v, want %#v", *gotVOD, wantVOD)
+	}
+
 	if gotData, err := os.ReadFile(path.Join(d, "vod", wantIdent+streamdata.ChannelVODSuffix)); err != nil {
 		t.Fatal(err)
 	} else if string(gotData) != string(wantData) {
 		t.Errorf("Add: data = %#v, want %#v", gotData, wantData)
 	}
+
+	if fi, err := os.Stat(path.Join(d, "vod", wantIdent)); err != nil {
+		t.Fatal(err)
+	} else if fi.Mode().Perm() != 0444 {
+		t.Errorf("Perm: %#o", fi.Mode().Perm())
+	}
+	if fi, err := os.Stat(path.Join(d, "vod", wantIdent+streamdata.ChannelVODSuffix)); err != nil {
+		t.Fatal(err)
+	} else if fi.Mode().Perm() != 0444 {
+		t.Errorf("Perm: %#o", fi.Mode().Perm())
+	}
+
+	if err := os.Chmod(path.Join(d, "vod", wantIdent), 0); err != nil {
+		t.Fatal(err)
+	}
+	wantErr = &os.PathError{
+		Op:   "openat",
+		Path: path.Join("vod", wantIdent),
+		Err:  syscall.EACCES,
+	}
+	if _, err := c.Load(&ident); !reflect.DeepEqual(err, wantErr) {
+		t.Fatalf("(perm) Load: error = %#v, want %#v", err, wantErr)
+	}
+
+	if err := os.Chmod(path.Join(d, "vod", wantIdent), 0600); err != nil {
+		t.Fatal(err)
+	} else if err = os.WriteFile(path.Join(d, "vod", wantIdent), nil, 0); err != nil {
+		t.Fatal(err)
+	}
+	wantErr = io.EOF
+	if _, err := c.Load(&ident); !reflect.DeepEqual(err, wantErr) {
+		t.Fatalf("(invalid) Load: error = %#v, want %#v", err, wantErr)
+	}
 }
 
 func TestErrors(t *testing.T) {