Add an option to avoid creating a tmpfs in prepare()

Root access is required for creating tmpfs mounts in the context of
the current mount namespace, and creating a tmpfs in the context of a
new mount namespace is less useful because a process in the parent
namespace can't easily access it.

So add an option to avoid creating tmpfs mounts, which will be used by
the rootless bootstrap mode for now.

In addition, when tmp directories aren't mounted as tmpfs, their
contents can't be removed using os.umount(). So instead remove them
recursively using shutil.rmtree().

lib/sysgeneral.py

@@ -3,11 +3,13 @@
 This file contains a few functions to be shared by all Sys* classes
 """
 
+# SPDX-FileCopyrightText: 2022 Dor Askayo <dor.askayo@gmail.com>
 # SPDX-FileCopyrightText: 2021-22 fosslinux <fosslinux@aussies.space>
 # SPDX-FileCopyrightText: 2021 Andrius Štikonas <andrius@stikonas.eu>
 # SPDX-License-Identifier: GPL-3.0-or-later
 
 import os
+import shutil
 import hashlib
 import glob
 import subprocess
@@ -33,10 +35,20 @@ class SysGeneral:
     mounted_tmpfs = False
 
     def __del__(self):
-        if self.mounted_tmpfs and not self.preserve_tmp:
+        if not self.preserve_tmp:
+            self.remove_tmp()
+
+    def remove_tmp(self):
+        """Remove the tmp directory"""
+        if self.tmp_dir is None:
+            return
+
+        if self.mounted_tmpfs:
             print(f"Unmounting tmpfs from {self.tmp_dir}")
             umount(self.tmp_dir)
-            os.rmdir(self.tmp_dir)
+
+        print(f"Removing {self.tmp_dir}")
+        shutil.rmtree(self.tmp_dir, ignore_errors=True)
 
     def mount_tmpfs(self):
         """Mount the tmpfs for this sysx"""