rebuildnodes: Support graceful shutdown

2 files changed, 29 insertions, 6 deletions

diff --git a/cmd/btrfs-rec/inspect_rebuildnodes.go b/cmd/btrfs-rec/inspect_rebuildnodes.go
index e61e6d2..9c86c3a 100644
--- a/cmd/btrfs-rec/inspect_rebuildnodes.go
+++ b/cmd/btrfs-rec/inspect_rebuildnodes.go
@@ -33,21 +33,31 @@ func init() {
 			}
 			dlog.Infof(ctx, "... done reading %q", args[0])
 
-			rebuiltNodes, err := rebuildnodes.RebuildNodes(ctx, fs, nodeScanResults)
+			rebuilder, err := rebuildnodes.NewRebuilder(ctx, fs, nodeScanResults)
 			if err != nil {
 				return err
 			}
 
-			dlog.Info(ctx, "Writing re-built nodes to stdout...")
-			if err := writeJSONFile(os.Stdout, rebuiltNodes, lowmemjson.ReEncoder{
+			dlog.Info(ctx, "Rebuilding node tree...")
+			rebuildErr := rebuilder.Rebuild(ctx)
+			dst := os.Stdout
+			if rebuildErr != nil {
+				dst = os.Stderr
+				dlog.Errorf(ctx, "rebuild error: %v", rebuildErr)
+			}
+			dlog.Infof(ctx, "Writing re-built nodes to %s...", dst.Name())
+			if err := writeJSONFile(dst, rebuilder.ListRoots(), lowmemjson.ReEncoder{
 				Indent:                "\t",
 				ForceTrailingNewlines: true,
 			}); err != nil {
+				if rebuildErr != nil {
+					return rebuildErr
+				}
 				return err
 			}
 			dlog.Info(ctx, "... done writing")
 
-			return nil
+			return rebuildErr
 		},
 	})
 }
diff --git a/cmd/btrfs-rec/util.go b/cmd/btrfs-rec/util.go
index ffc03cc..9a0d60c 100644
--- a/cmd/btrfs-rec/util.go
+++ b/cmd/btrfs-rec/util.go
@@ -18,6 +18,7 @@ import (
 )
 
 type runeScanner struct {
+	ctx            context.Context //nolint:containedctx // For detecting shutdown from methods
 	progress       textui.Portion[int64]
 	progressWriter *textui.Progress[textui.Portion[int64]]
 	unreadCnt      uint64
@@ -31,6 +32,7 @@ func newRuneScanner(ctx context.Context, fh *os.File) (*runeScanner, error) {
 		return nil, err
 	}
 	ret := &runeScanner{
+		ctx: ctx,
 		progress: textui.Portion[int64]{
 			D: fi.Size(),
 		},
@@ -42,6 +44,9 @@ func newRuneScanner(ctx context.Context, fh *os.File) (*runeScanner, error) {
 }
 
 func (rs *runeScanner) ReadRune() (r rune, size int, err error) {
+	if err := rs.ctx.Err(); err != nil {
+		return 0, 0, err
+	}
 	r, size, err = rs.reader.ReadRune()
 	if rs.unreadCnt > 0 {
 		rs.unreadCnt--
@@ -53,8 +58,14 @@ func (rs *runeScanner) ReadRune() (r rune, size int, err error) {
 }
 
 func (rs *runeScanner) UnreadRune() error {
+	if err := rs.ctx.Err(); err != nil {
+		return err
+	}
+	if err := rs.reader.UnreadRune(); err != nil {
+		return err
+	}
 	rs.unreadCnt++
-	return rs.reader.UnreadRune()
+	return nil
 }
 
 func (rs *runeScanner) Close() error {
@@ -69,6 +80,9 @@ func readJSONFile[T any](ctx context.Context, filename string) (T, error) {
 		return zero, err
 	}
 	buf, err := newRuneScanner(dlog.WithField(ctx, "btrfs.read-json-file", filename), fh)
+	defer func() {
+		_ = buf.Close()
+	}()
 	if err != nil {
 		var zero T
 		return zero, err
@@ -78,7 +92,6 @@ func readJSONFile[T any](ctx context.Context, filename string) (T, error) {
 		var zero T
 		return zero, err
 	}
-	_ = buf.Close()
 	return ret, nil
 }