1 files changed, 88 insertions, 0 deletions
diff --git a/lib/btrfsutil/rebuilt_callbacks.go b/lib/btrfsutil/rebuilt_callbacks.go
new file mode 100644
index 0000000..3a7e6e6
--- /dev/null
+++ b/lib/btrfsutil/rebuilt_callbacks.go
@@ -0,0 +1,88 @@
+// Copyright (C) 2022-2023  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package btrfsutil
+
+import (
+	"context"
+	"fmt"
+
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsitem"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
+)
+
+type RebuiltForrestCallbacks interface {
+	AddedRoot(ctx context.Context, tree btrfsprim.ObjID, root btrfsvol.LogicalAddr)
+	LookupRoot(ctx context.Context, tree btrfsprim.ObjID) (offset btrfsprim.Generation, item btrfsitem.Root, ok bool)
+	LookupUUID(ctx context.Context, uuid btrfsprim.UUID) (id btrfsprim.ObjID, ok bool)
+}
+
+type RebuiltForrestExtendedCallbacks interface {
+	RebuiltForrestCallbacks
+	AddedItem(ctx context.Context, tree btrfsprim.ObjID, key btrfsprim.Key)
+}
+
+type noopRebuiltForrestCallbacks struct {
+	forrest *RebuiltForrest
+}
+
+func (noopRebuiltForrestCallbacks) AddedRoot(context.Context, btrfsprim.ObjID, btrfsvol.LogicalAddr) {
+}
+
+func (cb noopRebuiltForrestCallbacks) LookupRoot(ctx context.Context, tree btrfsprim.ObjID) (offset btrfsprim.Generation, _item btrfsitem.Root, ok bool) {
+	rootTree := cb.forrest.RebuiltTree(ctx, btrfsprim.ROOT_TREE_OBJECTID)
+	if rootTree == nil {
+		return 0, btrfsitem.Root{}, false
+	}
+	tgt := btrfsprim.Key{
+		ObjectID: tree,
+		ItemType: btrfsprim.ROOT_ITEM_KEY,
+	}
+	itemKey, itemPtr, ok := rootTree.RebuiltAcquireItems(ctx).Search(func(key btrfsprim.Key, _ ItemPtr) int {
+		key.Offset = 0
+		return tgt.Compare(key)
+	})
+	rootTree.RebuiltReleaseItems()
+	if !ok {
+		return 0, btrfsitem.Root{}, false
+	}
+	itemBody := cb.forrest.readItem(ctx, itemPtr)
+	defer itemBody.Free()
+	switch itemBody := itemBody.(type) {
+	case *btrfsitem.Root:
+		return btrfsprim.Generation(itemKey.Offset), *itemBody, true
+	case *btrfsitem.Error:
+		return 0, btrfsitem.Root{}, false
+	default:
+		// This is a panic because the item decoder should not emit ROOT_ITEM items as anything but
+		// btrfsitem.Root or btrfsitem.Error without this code also being updated.
+		panic(fmt.Errorf("should not happen: ROOT_ITEM item has unexpected type: %T", itemBody))
+	}
+}
+
+func (cb noopRebuiltForrestCallbacks) LookupUUID(ctx context.Context, uuid btrfsprim.UUID) (id btrfsprim.ObjID, ok bool) {
+	uuidTree := cb.forrest.RebuiltTree(ctx, btrfsprim.UUID_TREE_OBJECTID)
+	if uuidTree == nil {
+		return 0, false
+	}
+	tgt := btrfsitem.UUIDToKey(uuid)
+	itemPtr, ok := uuidTree.RebuiltAcquireItems(ctx).Load(tgt)
+	uuidTree.RebuiltReleaseItems()
+	if !ok {
+		return 0, false
+	}
+	itemBody := cb.forrest.readItem(ctx, itemPtr)
+	defer itemBody.Free()
+	switch itemBody := itemBody.(type) {
+	case *btrfsitem.UUIDMap:
+		return itemBody.ObjID, true
+	case *btrfsitem.Error:
+		return 0, false
+	default:
+		// This is a panic because the item decoder should not emit UUID_SUBVOL items as anything but
+		// btrfsitem.UUIDMap or btrfsitem.Error without this code also being updated.
+		panic(fmt.Errorf("should not happen: UUID_SUBVOL item has unexpected type: %T", itemBody))
+	}
+}