pamd - fixed bug (#1538) (#1579)

* Fixed bug

- The module was searching back (and forward, in the ``after`` state) for lines that were not comments, assuming it would be a valid rule or an include.

* remove the line, make yamllint happy

* Update changelogs/fragments/1394-pamd-removing-comments.yaml

Co-authored-by: Felix Fontein <felix@fontein.de>

Co-authored-by: Felix Fontein <felix@fontein.de>
(cherry picked from commit 325a19d88a)

Co-authored-by: Alexei Znamensky <103110+russoz@users.noreply.github.com>

changelogs/fragments/1394-pamd-removing-comments.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+  - pamd - added logic to retain the comment line (https://github.com/ansible-collections/community.general/issues/1394).

plugins/modules/system/pamd.py

@@ -287,7 +287,7 @@ class PamdLine(object):
 
     @property
     def is_valid(self):
-        if self.line == '':
+        if self.line.strip() == '':
             return True
         return False
 
@@ -304,6 +304,10 @@ class PamdLine(object):
         return str(self.line)
 
 
+class PamdEmptyLine(PamdLine):
+    pass
+
+
 class PamdComment(PamdLine):
 
     def __init__(self, line):
@@ -445,8 +449,8 @@ class PamdService(object):
                 pamd_line = PamdComment(line)
             elif line.lstrip().startswith('@include'):
                 pamd_line = PamdInclude(line)
-            elif line == '':
+            elif line.strip() == '':
-                pamd_line = PamdLine(line)
+                pamd_line = PamdEmptyLine(line)
             else:
                 pamd_line = PamdRule.rule_from_string(line)
 
@@ -545,7 +549,7 @@ class PamdService(object):
 
             # Next we may have to loop backwards if the previous line is a comment.  If it
             # is, we'll get the previous "rule's" previous.
-            while previous_rule is not None and isinstance(previous_rule, PamdComment):
+            while previous_rule is not None and isinstance(previous_rule, (PamdComment, PamdEmptyLine)):
                 previous_rule = previous_rule.prev
             # Next we'll see if the previous rule matches what we are trying to insert.
             if previous_rule is not None and not previous_rule.matches(new_type, new_control, new_path):
@@ -589,7 +593,7 @@ class PamdService(object):
             next_rule = current_rule.next
             # Next we may have to loop forwards if the next line is a comment.  If it
             # is, we'll get the next "rule's" next.
-            while next_rule is not None and isinstance(next_rule, PamdComment):
+            while next_rule is not None and isinstance(next_rule, (PamdComment, PamdEmptyLine)):
                 next_rule = next_rule.next
 
             # First we create a new rule
@@ -780,13 +784,8 @@ def main():
         required_if=[
             ("state", "args_present", ["module_arguments"]),
             ("state", "args_absent", ["module_arguments"]),
-            ("state", "before", ["new_control"]),
+            ("state", "before", ["new_control", "new_type", "new_module_path"]),
-            ("state", "before", ["new_type"]),
+            ("state", "after", ["new_control", "new_type", "new_module_path"]),
-            ("state", "before", ["new_module_path"]),
-            ("state", "after", ["new_control"]),
-            ("state", "after", ["new_type"]),
-            ("state", "after", ["new_module_path"]),
-
         ],
     )
     content = str()
@@ -798,9 +797,7 @@ def main():
             content = service_file_obj.read()
     except IOError as e:
         # If unable to read the file, fail out
-        module.fail_json(msg='Unable to open/read PAM module \
+        module.fail_json(msg='Unable to open/read PAM module file %s with error %s.' % (fname, str(e)))
-                            file %s with error %s.' %
-                         (fname, str(e)))
 
     # Assuming we didn't fail, create the service
     service = PamdService(content)