errcheck: Add error checks

Most added checks are straight forward.

internal/backend/foreground_test.go

@@ -23,7 +23,9 @@ func TestForeground(t *testing.T) {
 
 	bg, err := backend.StartForeground(cmd)
 	rtest.OK(t, err)
-	defer cmd.Wait()
+	defer func() {
+		rtest.OK(t, cmd.Wait())
+	}()
 
 	err = bg()
 	rtest.OK(t, err)

internal/fuse/snapshots_dir.go

@@ -229,7 +229,10 @@ func updateSnapshots(ctx context.Context, root *Root) error {
 
 	if root.snCount != len(snapshots) {
 		root.snCount = len(snapshots)
-		root.repo.LoadIndex(ctx)
+		err := root.repo.LoadIndex(ctx)
+		if err != nil {
+			return err
+		}
 		root.snapshots = snapshots
 	}
 	root.lastCheck = time.Now()
@@ -272,7 +275,10 @@ func (d *SnapshotsDir) ReadDirAll(ctx context.Context) ([]fuse.Dirent, error) {
 	debug.Log("ReadDirAll()")
 
 	// update snapshots
-	updateSnapshots(ctx, d.root)
+	err := updateSnapshots(ctx, d.root)
+	if err != nil {
+		return nil, err
+	}
 
 	// update snapshot names
 	updateSnapshotNames(d, d.root.cfg.SnapshotTemplate)
@@ -314,7 +320,10 @@ func (d *SnapshotsIDSDir) ReadDirAll(ctx context.Context) ([]fuse.Dirent, error)
 	debug.Log("ReadDirAll()")
 
 	// update snapshots
-	updateSnapshots(ctx, d.root)
+	err := updateSnapshots(ctx, d.root)
+	if err != nil {
+		return nil, err
+	}
 
 	// update snapshot ids
 	updateSnapshotIDSNames(d)
@@ -348,7 +357,10 @@ func (d *HostsDir) ReadDirAll(ctx context.Context) ([]fuse.Dirent, error) {
 	debug.Log("ReadDirAll()")
 
 	// update snapshots
-	updateSnapshots(ctx, d.root)
+	err := updateSnapshots(ctx, d.root)
+	if err != nil {
+		return nil, err
+	}
 
 	// update host names
 	updateHostsNames(d)
@@ -382,7 +394,10 @@ func (d *TagsDir) ReadDirAll(ctx context.Context) ([]fuse.Dirent, error) {
 	debug.Log("ReadDirAll()")
 
 	// update snapshots
-	updateSnapshots(ctx, d.root)
+	err := updateSnapshots(ctx, d.root)
+	if err != nil {
+		return nil, err
+	}
 
 	// update tag names
 	updateTagNames(d)
@@ -443,7 +458,10 @@ func (d *SnapshotsDir) Lookup(ctx context.Context, name string) (fs.Node, error)
 	sn, ok := d.names[name]
 	if !ok {
 		// could not find entry. Updating repository-state
-		updateSnapshots(ctx, d.root)
+		err := updateSnapshots(ctx, d.root)
+		if err != nil {
+			return nil, err
+		}
 
 		// update snapshot names
 		updateSnapshotNames(d, d.root.cfg.SnapshotTemplate)
@@ -476,7 +494,10 @@ func (d *SnapshotsIDSDir) Lookup(ctx context.Context, name string) (fs.Node, err
 	sn, ok := d.names[name]
 	if !ok {
 		// could not find entry. Updating repository-state
-		updateSnapshots(ctx, d.root)
+		err := updateSnapshots(ctx, d.root)
+		if err != nil {
+			return nil, err
+		}
 
 		// update snapshot ids
 		updateSnapshotIDSNames(d)
@@ -499,7 +520,10 @@ func (d *HostsDir) Lookup(ctx context.Context, name string) (fs.Node, error) {
 	_, ok := d.hosts[name]
 	if !ok {
 		// could not find entry. Updating repository-state
-		updateSnapshots(ctx, d.root)
+		err := updateSnapshots(ctx, d.root)
+		if err != nil {
+			return nil, err
+		}
 
 		// update host names
 		updateHostsNames(d)
@@ -522,7 +546,10 @@ func (d *TagsDir) Lookup(ctx context.Context, name string) (fs.Node, error) {
 	_, ok := d.tags[name]
 	if !ok {
 		// could not find entry. Updating repository-state
-		updateSnapshots(ctx, d.root)
+		err := updateSnapshots(ctx, d.root)
+		if err != nil {
+			return nil, err
+		}
 
 		// update tag names
 		updateTagNames(d)

internal/hashing/writer.go

@@ -21,8 +21,16 @@ func NewWriter(w io.Writer, h hash.Hash) *Writer {
 
 // Write wraps the write method of the underlying writer and also hashes all data.
 func (h *Writer) Write(p []byte) (int, error) {
+	// write the data to the underlying writing
 	n, err := h.w.Write(p)
-	h.h.Write(p[:n])
+
+	// according to the interface documentation, Write() on a hash.Hash never
+	// returns an error.
+	_, hashErr := h.h.Write(p[:n])
+	if hashErr != nil {
+		panic(hashErr)
+	}
+
 	return n, err
 }
 

internal/repository/index_test.go

@@ -301,7 +301,11 @@ var (
 func initBenchmarkIndexJSON() {
 	idx, _ := createRandomIndex(rand.New(rand.NewSource(0)), 200000)
 	var buf bytes.Buffer
-	idx.Encode(&buf)
+	err := idx.Encode(&buf)
+	if err != nil {
+		panic(err)
+	}
+
 	benchmarkIndexJSON = buf.Bytes()
 }
 

internal/repository/master_index_test.go

@@ -338,7 +338,10 @@ func TestIndexSave(t *testing.T) {
 	repo, cleanup := createFilledRepo(t, 3, 0)
 	defer cleanup()
 
-	repo.LoadIndex(context.TODO())
+	err := repo.LoadIndex(context.TODO())
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	obsoletes, err := repo.Index().(*repository.MasterIndex).Save(context.TODO(), repo, nil, nil, nil)
 	if err != nil {

internal/repository/repack_test.go

@@ -201,7 +201,11 @@ func rebuildIndex(t *testing.T, repo restic.Repository) {
 }
 
 func reloadIndex(t *testing.T, repo restic.Repository) {
-	repo.SetIndex(repository.NewMasterIndex())
+	err := repo.SetIndex(repository.NewMasterIndex())
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	if err := repo.LoadIndex(context.TODO()); err != nil {
 		t.Fatalf("error loading new index: %v", err)
 	}

internal/repository/repository.go

@@ -781,16 +781,19 @@ func DownloadAndHash(ctx context.Context, be Loader, h restic.Handle) (tmpfile *
 		hash = restic.IDFromHash(hrd.Sum(nil))
 		return ierr
 	})
+
 	if err != nil {
-		tmpfile.Close()
-		os.Remove(tmpfile.Name())
+		// ignore subsequent errors
+		_ = tmpfile.Close()
+		_ = os.Remove(tmpfile.Name())
 		return nil, restic.ID{}, -1, errors.Wrap(err, "Load")
 	}
 
 	_, err = tmpfile.Seek(0, io.SeekStart)
 	if err != nil {
-		tmpfile.Close()
-		os.Remove(tmpfile.Name())
+		// ignore subsequent errors
+		_ = tmpfile.Close()
+		_ = os.Remove(tmpfile.Name())
 		return nil, restic.ID{}, -1, errors.Wrap(err, "Seek")
 	}