Fix user module to not create /nonexistent on FreeBSD (#86415)

Fixes an issue where the user module would create the /nonexistent directory when modifying a user to add them to a group on FreeBSD. The /nonexistent path is a standard convention for system accounts on FreeBSD that should not exist physically on disk.

This commit adds a check in the FreeBsdUser.modify_user() method to skip home directory creation when the home path is /nonexistent.

Fixes #86368

Co-authored-by: zykov <zykov@biocad.ru>

changelogs/fragments/86368-user-freebsd-nonexistent.yml

@@ -0,0 +1,2 @@
+bugfixes:
+  - user - fix ``FreeBsdUser`` to not create ``/nonexistent`` directory when modifying user to add them to a group on FreeBSD (https://github.com/ansible/ansible/issues/86368)

lib/ansible/modules/user.py

@@ -512,6 +512,15 @@ from ansible.module_utils.common.locale import get_best_parsable_locale
 from ansible.module_utils.common.sys_info import get_platform_subclass
 
 
+# Placeholder home directories that should never be physically created on disk
+# These are conventions for system accounts that should not have real home directories
+PLACEHOLDER_HOME_DIRS = frozenset([
+    '/nonexistent',  # FreeBSD convention for system accounts (www, nobody, etc.)
+    '/dev/null',     # Used on some Linux systems for system accounts
+    '/var/empty',    # OpenBSD convention for privilege-separated processes
+])
+
+
 class StructSpwdType(ctypes.Structure):
     _fields_ = [
         ('sp_namp', ctypes.c_char_p),
@@ -1586,7 +1595,9 @@ class FreeBsdUser(User):
             cmd.append(self.comment)
 
         if self.home is not None:
-            if (info[5] != self.home and self.move_home) or (not os.path.exists(self.home) and self.create_home):
+            # Skip home creation for placeholder directories (e.g., /nonexistent, /dev/null)
+            # These are conventions for system accounts and should not be created on disk
+            if (info[5] != self.home and self.move_home) or (info[5] not in PLACEHOLDER_HOME_DIRS and not os.path.exists(self.home) and self.create_home):
                 cmd.append('-m')
             if info[5] != self.home:
                 cmd.append('-d')
@@ -3405,7 +3416,7 @@ def main():
         info = user.user_info()
         if user.home is None:
             user.home = info[5]
-        if not os.path.exists(user.home) and user.create_home:
+        if not os.path.exists(user.home) and user.home not in PLACEHOLDER_HOME_DIRS and user.create_home:
             if not module.check_mode:
                 user.create_homedir(user.home)
                 user.chown_homedir(info[2], info[3], user.home)

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

@@ -33,4 +33,6 @@
   when:
     - ansible_facts.system == 'Linux'
     - ansible_distribution != 'Alpine'
+- include_tasks: test_freebsd_nonexistent.yml
+  when: ansible_facts.system == 'FreeBSD'
 - import_tasks: ssh_keygen.yml

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

@@ -0,0 +1,47 @@
+---
+# Test for issue #86368 - ensure /nonexistent is not created on FreeBSD
+# when modifying a user to add them to a group
+
+- name: Create a test user with /nonexistent as home directory
+  user:
+    name: ansibulltestuser
+    home: /nonexistent
+    create_home: no
+    state: present
+  register: user_create
+
+- name: Create a test group
+  group:
+    name: ansibulltestgroup
+    state: present
+
+- name: Add user to group (should not create /nonexistent)
+  user:
+    name: ansibulltestuser
+    groups: ansibulltestgroup
+    append: true
+  register: user_modify
+
+- name: Check if /nonexistent was created (it should not exist)
+  stat:
+    path: /nonexistent
+  register: nonexistent_stat
+
+- name: Validate that /nonexistent was not created
+  assert:
+    that:
+      - user_create is changed
+      - user_modify is changed
+      - not nonexistent_stat.stat.exists
+    fail_msg: "/nonexistent directory should not be created when adding user to group"
+
+- name: Clean up - remove test user
+  user:
+    name: ansibulltestuser
+    state: absent
+    force: true
+
+- name: Clean up - remove test group
+  group:
+    name: ansibulltestgroup
+    state: absent