Throw a prettier error in m_u.basic syslog (#70312)

Change:
- In certain situations, such as when the input string contains null
  bytes (\0), syslog.syslog will throw a TypeError. Handle that and
  fail_json instead.

Test Plan:
- New test
- ansible-test --docker centos[68] (for py2 and py3 respectively)

Tickets:
- Refs #70269

Signed-off-by: Rick Elrod <rick@elrod.me>

changelogs/fragments/syslog-prettier-error.yml

@@ -0,0 +1,2 @@
+minor_changes:
+  - The logging functionality in module_utils.basic now returns a nicer error when it falls back to syslog but ends up getting a TypeError thrown back.

lib/ansible/module_utils/basic.py

@@ -1879,10 +1879,19 @@ class AnsibleModule(object):
 
     def _log_to_syslog(self, msg):
         if HAS_SYSLOG:
+            try:
                 module = 'ansible-%s' % self._name
                 facility = getattr(syslog, self._syslog_facility, syslog.LOG_USER)
                 syslog.openlog(str(module), 0, facility)
                 syslog.syslog(syslog.LOG_INFO, msg)
+            except TypeError as e:
+                self.fail_json(
+                    msg='Failed to log to syslog (%s). To proceed anyway, '
+                        'disable syslog logging by setting no_target_syslog '
+                        'to True in your Ansible config.' % to_native(e),
+                    exception=traceback.format_exc(),
+                    msg_to_log=msg,
+                )
 
     def debug(self, msg):
         if self._debug:

test/integration/targets/module_utils/module_utils_test.yml

@@ -60,3 +60,40 @@
       that:
         - result.deprecations[0].msg == "Alias 'baz' is deprecated. See the module docs for more information"
         - result.deprecations[0].version == '9.99'
+
+  - block:
+      - name: Get a string with a \0 in it
+        command: echo -e 'hi\0foo'
+        register: string_with_null
+
+      - name: Use the null string as a module parameter
+        lineinfile:
+          path: "{{ output_dir }}/nulltest"
+          line: "{{ string_with_null.stdout }}"
+          create: yes
+        ignore_errors: yes
+        register: nulltest
+
+      - name: See if the file exists
+        stat:
+          path: "{{ output_dir }}/nulltest"
+        register: nullstat
+
+      - assert:
+          that:
+            - nulltest is failed
+            - nulltest.msg_to_log.startswith('Invoked ')
+            - nulltest.msg.startswith('Failed to log to syslog')
+        # Conditionalize this, because when we log with something other than
+        # syslog, it's probably successful and these assertions will fail.
+        when: nulltest is failed
+
+      # Ensure we fail out early and don't actually run the module if logging
+      # failed.
+      - assert:
+          that:
+            - nullstat.stat.exists == nulltest is successful
+    always:
+      - file:
+          path: "{{ output_dir }}/nulltest"
+          state: absent

test/integration/targets/module_utils/runme.sh

@@ -8,6 +8,6 @@ ANSIBLE_ROLES_PATH=../ ansible-playbook module_utils_basic_setcwd.yml -i ../../i
 # doesn't traceback with unicode in the custom module_utils directory path.
 ansible-playbook module_utils_vvvvv.yml -i ../../inventory -vvvvv "$@"
 
-ansible-playbook module_utils_test.yml -i ../../inventory -v "$@"
+ansible-playbook module_utils_test.yml -i ../../inventory -e output_dir="$OUTPUT_DIR" -v "$@"
 
 ANSIBLE_MODULE_UTILS=other_mu_dir ansible-playbook module_utils_envvar.yml -i ../../inventory -v "$@"