Fix local facts unreadable (#76095)

* Catch exceptions during stat calls

If such an exception is not caught it causes the complete
local facts gathering to fail.

changelogs/fragments/local_fact_unreadable.yml

@@ -0,0 +1,6 @@
+bugfixes:
+  - >-
+     local facts - if a local fact in the facts directory cannot be stated,
+     store an error message as the fact value and emit a warning just as if
+     just as if the facts execution has failed. The stat can fail e.g. on
+     dangling symlinks.

lib/ansible/module_utils/facts/system/local.py

@@ -50,8 +50,15 @@ class LocalFactCollector(BaseFactCollector):
         for fn in sorted(glob.glob(fact_path + '/*.fact')):
             # use filename for key where it will sit under local facts
             fact_base = os.path.basename(fn).replace('.fact', '')
-            if stat.S_IXUSR & os.stat(fn)[stat.ST_MODE]:
-                failed = None
+            failed = None
+            try:
+                executable_fact = stat.S_IXUSR & os.stat(fn)[stat.ST_MODE]
+            except OSError as e:
+                failed = 'Could not stat fact (%s): %s' % (fn, to_text(e))
+                local[fact_base] = failed
+                module.warn(failed)
+                continue
+            if executable_fact:
                 try:
                     # run it
                     rc, out, err = module.run_command(fn)

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

@@ -20,6 +20,13 @@
         - name: unreadable
           mode: '0000'
 
+    - name: Create dangling symlink
+      file:
+        path: "{{ fact_dir }}/dead_symlink.fact"
+        src: /tmp/dead_symlink
+        force: yes
+        state: link
+
 - name: force fact gather to get ansible_local
   setup:
     fact_path: "{{ fact_dir | expanduser }}"
@@ -43,3 +50,4 @@
         - setup_result['ansible_facts']['ansible_local']['goodscript']['script_ran']|bool
         - setup_result['ansible_facts']['ansible_local']['basdscript'].startswith("Failure executing fact script")
         - setup_result['ansible_facts']['ansible_local']['unreadable'].startswith('error loading facts')
+        - setup_result['ansible_facts']['ansible_local']['dead_symlink'].startswith('Could not stat fact')