Check if skeleton is /dev/null while creating home folder (#75948)

* Check if skeleton is /dev/null while creating home folder

* Add test for linux

Co-authored-by: Holger Dörner <h.doerner@bitexpert.de>
Co-authored-by: Brian Coca <bcoca@users.noreply.github.com>

changelogs/fragments/75063-allow-dev-nul-as-skeleton-for-new-homedir.yml

@@ -0,0 +1,3 @@
+bugfixes:
+  - modules/user.py - Add check for valid directory when creating new user homedir (allows /dev/null as skeleton) (https://github.com/ansible/ansible/issues/75063)
+  

lib/ansible/modules/user.py

@@ -1273,7 +1273,7 @@ class User(object):
             else:
                 skeleton = '/etc/skel'
 
-            if os.path.exists(skeleton):
+            if os.path.exists(skeleton) and skeleton != os.devnull:
                 try:
                     shutil.copytree(skeleton, path, symlinks=True)
                 except OSError as e:

test/integration/targets/user/tasks/test_create_user_home.yml

@@ -134,3 +134,21 @@
     name: randomuser
     state: absent
     remove: yes
+
+- name: Create user home directory with /dev/null as skeleton, https://github.com/ansible/ansible/issues/75063
+  # create_homedir is mostly used by linux, rest of OSs take care of it themselves via -k option (which fails this task)
+  when: ansible_system == 'Linux'  
+  block:
+    - name: "Create user home directory with /dev/null as skeleton"
+      user:
+        name: withskeleton
+        state: present
+        skeleton: "/dev/null"
+        createhome: yes
+      register: create_user_with_skeleton_dev_null
+  always:
+    - name: "Remove test user"
+      user:
+        name: withskeleton
+        state: absent
+        remove: yes