FileFetcher respects cancelled context

client/fetcher.go

@@ -116,18 +116,27 @@ type FileFetcher struct {
 	Root string
 }
 
-func (f FileFetcher) ReadCheckpoint(_ context.Context) ([]byte, error) {
+func (f FileFetcher) ReadCheckpoint(ctx context.Context) ([]byte, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
 	return os.ReadFile(path.Join(f.Root, layout.CheckpointPath))
 }
 
 func (f FileFetcher) ReadTile(ctx context.Context, l, i uint64, p uint8) ([]byte, error) {
 	return fetcher.PartialOrFullResource(ctx, p, func(ctx context.Context, p uint8) ([]byte, error) {
+		if err := ctx.Err(); err != nil {
+			return nil, err
+		}
 		return os.ReadFile(path.Join(f.Root, layout.TilePath(l, i, p)))
 	})
 }
 
 func (f FileFetcher) ReadEntryBundle(ctx context.Context, i uint64, p uint8) ([]byte, error) {
 	return fetcher.PartialOrFullResource(ctx, p, func(ctx context.Context, p uint8) ([]byte, error) {
+		if err := ctx.Err(); err != nil {
+			return nil, err
+		}
 		return os.ReadFile(path.Join(f.Root, layout.EntriesPath(i, p)))
 	})
 }

client/fetcher_test.go

@@ -0,0 +1,33 @@
+package client
+
+import (
+	"context"
+	"errors"
+	"testing"
+)
+
+func TestFileFetcherContextCancellation(t *testing.T) {
+	d := t.TempDir()
+
+	f := FileFetcher{
+		Root: d,
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel() // Cancel immediately
+
+	_, err := f.ReadCheckpoint(ctx)
+	if !errors.Is(err, context.Canceled) {
+		t.Errorf("ReadCheckpoint: got error %v, want %v", err, context.Canceled)
+	}
+
+	_, err = f.ReadTile(ctx, 0, 0, 255)
+	if !errors.Is(err, context.Canceled) {
+		t.Errorf("ReadTile: got error %v, want %v", err, context.Canceled)
+	}
+
+	_, err = f.ReadEntryBundle(ctx, 0, 255)
+	if !errors.Is(err, context.Canceled) {
+		t.Errorf("ReadEntryBundle: got error %v, want %v", err, context.Canceled)
+	}
+}

fsck/status_test.go

@@ -171,6 +171,7 @@ func TestUpdate(t *testing.T) {
 			for i, want := range test.wantRanges {
 				if p == nil {
 					t.Fatalf("got %d entry ranges, want %d", i-1, len(test.wantRanges))
+					return // To make the linter happy
 				}
 				got := p.Value.(*Range)
 				if !reflect.DeepEqual(*got, want) {

internal/fetcher/fallback.go

@@ -38,7 +38,7 @@ func PartialOrFullResource(ctx context.Context, p uint8, f func(context.Context,
 		}
 		return sRaw, nil
 	case err != nil:
-		return sRaw, fmt.Errorf("failed to fetch resource: %v", err)
+		return sRaw, fmt.Errorf("failed to fetch resource: %w", err)
 	default:
 		return sRaw, nil
 	}