Fix mount_overlay() with multiple lowerdirs

Multiple lower directories are specified by delimiting with colons,
not by specifying the lowerdir= option multiple times. Also, the
lowerdirs are stacked right to left so make sure we reverse the given
list.

diff --git a/mkosi/mounts.py b/mkosi/mounts.py
index 791f760133e4525694c009cb0892470ea6c7e351..bc1dd5405b2532c2fddc841ebc763e0a04675547 100644 (file)
--- a/mkosi/mounts.py
+++ b/mkosi/mounts.py
@@ -74,7 +74,8 @@ def mount(
 @contextlib.contextmanager
 def mount_overlay(lowerdirs: Sequence[Path], upperdir: Path, where: Path) -> Iterator[Path]:
     with tempfile.TemporaryDirectory(dir=upperdir.parent, prefix=f"{upperdir.name}-workdir") as workdir:
-        options = [f"lowerdir={lower}" for lower in lowerdirs] + [
+        options = [
+            f"lowerdir={':'.join(os.fspath(p) for p in reversed(lowerdirs))}",
             f"upperdir={upperdir}",
             f"workdir={workdir}",
             # Disable the inodes index and metacopy (only copy metadata upwards if possible)