util: specify a not empty pause dir for root too

commit b3014c1 changed
GetRootlessRuntimeDir() to return an empty string for root, so that
its value is not exported as XDG_RUNTIME_DIR, and other programs like
crun can use a better default.

Now GetRootlessPauseProcessPidPath() uses homedir.GetRuntimeDir().
The homedir.GetRuntimeDir() function returns a value also when running
as root so it can be used inside a nested Podman.

Closes: containers#22327

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

pkg/util/utils_supported.go

@@ -28,7 +28,7 @@ func GetRootlessConfigHomeDir() (string, error) {
 // GetRootlessPauseProcessPidPath returns the path to the file that holds the pid for
 // the pause process.
 func GetRootlessPauseProcessPidPath() (string, error) {
-	runtimeDir, err := GetRootlessRuntimeDir()
+	runtimeDir, err := homedir.GetRuntimeDir()
 	if err != nil {
 		return "", err
 	}

pkg/util/utils_test.go

@@ -764,3 +764,9 @@ func TestProcessOptions(t *testing.T) {
 		})
 	}
 }
+
+func TestGetRootlessPauseProcessPidPath(t *testing.T) {
+	dir, err := GetRootlessPauseProcessPidPath()
+	assert.NoError(t, err)
+	assert.NotEqual(t, dir, "libpod/tmp/pause.pid")
+}