object/store/packed: Add quarantine

1 files changed, 63 insertions, 0 deletions

diff --git a/object/store/packed/quarantine_begin.go b/object/store/packed/quarantine_begin.go
new file mode 100644
index 00000000..06b9a8a6
--- /dev/null
+++ b/object/store/packed/quarantine_begin.go
@@ -0,0 +1,63 @@
+package packed
+
+import (
+	"crypto/rand"
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+
+	objectstore "codeberg.org/lindenii/furgit/object/store"
+)
+
+// BeginPackQuarantine creates one quarantined packed store rooted privately
+// beneath the destination pack root.
+//
+// Labels: Deps-Borrowed, Life-Parent, Close-No.
+func (store *Store) BeginPackQuarantine(_ objectstore.PackQuarantineOptions) (objectstore.PackQuarantine, error) {
+	tempName, tempRoot, err := createPackQuarantineRoot(store.root)
+	if err != nil {
+		return nil, err
+	}
+
+	quarantineStore, err := New(tempRoot, store.algo, store.opts)
+	if err != nil {
+		_ = tempRoot.Close()
+		_ = store.root.RemoveAll(tempName)
+
+		return nil, err
+	}
+
+	return &packQuarantine{
+		Store:    quarantineStore,
+		parent:   store,
+		tempName: tempName,
+		tempRoot: tempRoot,
+	}, nil
+}
+
+func createPackQuarantineRoot(parent *os.Root) (string, *os.Root, error) {
+	for range 32 {
+		name := "tmp_packq_" + rand.Text()
+
+		err := parent.Mkdir(name, 0o700)
+		if err == nil {
+			root, err := parent.OpenRoot(name)
+			if err == nil {
+				return name, root, nil
+			}
+
+			_ = parent.RemoveAll(name)
+
+			return "", nil, err
+		}
+
+		if errors.Is(err, fs.ErrExist) {
+			continue
+		}
+
+		return "", nil, err
+	}
+
+	return "", nil, fmt.Errorf("packed: unable to create quarantine directory")
+}