Strip junk after JSON return. (#15822)

Fixes #15601

lib/ansible/plugins/action/__init__.py

@@ -324,7 +324,7 @@ class ActionBase(with_metaclass(ABCMeta, object)):
             # contain a path to a tmp dir but doesn't know if it needs to
             # exist or not.  If there's no path, then there's no need for us
             # to do work
-            self._display.debug('_fixup_perms called with remote_path==None.  Sure this is correct?')
+            display.debug('_fixup_perms called with remote_path==None.  Sure this is correct?')
             return remote_path
 
         if self._play_context.become and self._play_context.become_user not in ('root', remote_user):
@@ -360,7 +360,7 @@ class ActionBase(with_metaclass(ABCMeta, object)):
                     if C.ALLOW_WORLD_READABLE_TMPFILES:
                         # fs acls failed -- do things this insecure way only
                         # if the user opted in in the config file
-                        self._display.warning('Using world-readable permissions for temporary files Ansible needs to create when becoming an unprivileged user which may be insecure. For information on securing this, see https://docs.ansible.com/ansible/become.html#becoming-an-unprivileged-user')
+                        display.warning('Using world-readable permissions for temporary files Ansible needs to create when becoming an unprivileged user which may be insecure. For information on securing this, see https://docs.ansible.com/ansible/become.html#becoming-an-unprivileged-user')
                         res = self._remote_chmod('a+%s' % mode, remote_path, recursive=recursive)
                         if res['rc'] != 0:
                             raise AnsibleError('Failed to set file mode on remote files (rc: {0}, err: {1})'.format(res['rc'], res['stderr']))
@@ -480,21 +480,49 @@ class ActionBase(with_metaclass(ABCMeta, object)):
         else:
             return initial_fragment
 
-    def _filter_leading_non_json_lines(self, data):
+    @staticmethod
+    def _filter_non_json_lines(data):
         '''
         Used to avoid random output from SSH at the top of JSON output, like messages from
         tcagetattr, or where dropbear spews MOTD on every single command (which is nuts).
 
-        need to filter anything which starts not with '{', '[', ', '=' or is an empty line.
+        need to filter anything which does not start with '{', '[', or is an empty line.
-        filter only leading lines since multiline JSON is valid.
+        Have to be careful how we filter trailing junk as multiline JSON is valid.
         '''
-        idx = 0
+        # Filter initial junk
-        for line in data.splitlines(True):
+        lines = data.splitlines()
-            if line.startswith((u'{', u'[')):
+        for start, line in enumerate(lines):
+            line = line.strip()
+            if line.startswith(u'{'):
+                endchar = u'}'
                 break
-            idx = idx + len(line)
+            elif line.startswith(u'['):
+                endchar = u']'
+                break
+        else:
+            display.debug('No start of json char found')
+            raise ValueError('No start of json char found')
+
+        # Filter trailing junk
+        lines = lines[start:]
+        lines.reverse()
+        for end, line in enumerate(lines):
+            if line.strip().endswith(endchar):
+                break
+        else:
+            display.debug('No end of json char found')
+            raise ValueError('No end of json char found')
+
+        if end < len(lines) - 1:
+            # Trailing junk is uncommon and can point to things the user might
+            # want to change.  So print a warning if we find any
+            trailing_junk = lines[:end]
+            trailing_junk.reverse()
+            display.warning('Module invocation had junk after the JSON data: %s' % '\n'.join(trailing_junk))
 
-        return data[idx:]
+        lines = lines[end:]
+        lines.reverse()
+        return '\n'.join(lines)
 
     def _strip_success_message(self, data):
         '''
@@ -539,7 +567,7 @@ class ActionBase(with_metaclass(ABCMeta, object)):
         module_args['_ansible_diff'] = self._play_context.diff
 
         # let module know our verbosity
-        module_args['_ansible_verbosity'] = self._display.verbosity
+        module_args['_ansible_verbosity'] = display.verbosity
 
         (module_style, shebang, module_data) = self._configure_module(module_name=module_name, module_args=module_args, task_vars=task_vars)
         if not shebang:
@@ -627,7 +655,7 @@ class ActionBase(with_metaclass(ABCMeta, object)):
 
     def _parse_returned_data(self, res):
         try:
-            data = json.loads(self._filter_leading_non_json_lines(res.get('stdout', u'')))
+            data = json.loads(self._filter_non_json_lines(res.get('stdout', u'')))
         except ValueError:
             # not valid json, lets try to capture error
             data = dict(failed=True, parsed=False)

test/units/plugins/action/test_action.py

@@ -33,6 +33,8 @@ try:
 except ImportError:
     import __builtin__ as builtins
 
+from nose.tools import eq_, raises
+
 from ansible.release import __version__ as ansible_version
 from ansible import constants as C
 from ansible.compat.six import text_type
@@ -630,3 +632,42 @@ class TestActionBase(unittest.TestCase):
             play_context.make_become_cmd.assert_called_once_with("ECHO SAME", executable=None)
         finally:
             C.BECOME_ALLOW_SAME_USER = become_allow_same_user
+
+# Note: Using nose's generator test cases here so we can't inherit from
+# unittest.TestCase
+class TestFilterNonJsonLines(object):
+    parsable_cases = (
+            (u'{"hello": "world"}', u'{"hello": "world"}'),
+            (u'{"hello": "world"}\n', u'{"hello": "world"}'),
+            (u'{"hello": "world"} ', u'{"hello": "world"} '),
+            (u'{"hello": "world"} \n', u'{"hello": "world"} '),
+            (u'Message of the Day\n{"hello": "world"}', u'{"hello": "world"}'),
+            (u'{"hello": "world"}\nEpilogue', u'{"hello": "world"}'),
+            (u'Several\nStrings\nbefore\n{"hello": "world"}\nAnd\nAfter\n', u'{"hello": "world"}'),
+            (u'{"hello": "world",\n"olá": "mundo"}', u'{"hello": "world",\n"olá": "mundo"}'),
+            (u'\nPrecedent\n{"hello": "world",\n"olá": "mundo"}\nAntecedent', u'{"hello": "world",\n"olá": "mundo"}'),
+            )
+
+    unparsable_cases = (
+            u'No json here',
+            u'"olá": "mundo"',
+            u'{"No json": "ending"',
+            u'{"wrong": "ending"]',
+            u'["wrong": "ending"}',
+            )
+
+    def check_filter_non_json_lines(self, stdout_line, parsed):
+        eq_(parsed, ActionBase._filter_non_json_lines(stdout_line))
+
+    def test_filter_non_json_lines(self):
+        for stdout_line, parsed in self.parsable_cases:
+            yield self.check_filter_non_json_lines, stdout_line, parsed
+
+    @raises(ValueError)
+    def check_unparsable_filter_non_json_lines(self, stdout_line):
+        ActionBase._filter_non_json_lines(stdout_line)
+
+    def test_unparsable_filter_non_json_lines(self):
+        for stdout_line in self.unparsable_cases:
+            yield self.check_unparsable_filter_non_json_lines, stdout_line
+