copy action plug-in check mode respects force=no

The copy action accepts force=no, which tells it not to replace an
existing file even if it differs from the source.  The copy action
plug-in wasn't respecting this option when operated in check mode, so it
would report that changes are necessary in check mode even though copy
would make no changes when run normally.

Runner._remote_md5 was changed to make the logic for setting rc perhaps
a little more clear, and to make sure that rc=0 when the file does not
exist.

lib/ansible/runner/__init__.py

@@ -584,7 +584,11 @@ class Runner(object):
         ''' takes a remote md5sum without requiring python, and returns 0 if no file '''
 
         path = pipes.quote(path)
-        test = "rc=0; [ -r \"%s\" ] || rc=2; [ -f \"%s\" ] || rc=1; [ -d \"%s\" ] && rc=3" % (path, path, path)
+        test = ('if [ ! -e \"%s\" ]; then rc=0;'
+                'elif [ -d \"%s\" ]; then rc=3;'
+                'elif [ ! -f \"%s\" ]; then rc=1;'
+                'elif [ ! -r \"%s\" ]; then rc=2;'
+                'else rc=0; fi') % ((path,) * 4)
         md5s = [
             "(/usr/bin/md5sum %s 2>/dev/null)" % path,  # Linux
             "(/sbin/md5sum -q %s 2>/dev/null)" % path,  # ?

lib/ansible/runner/action_plugins/copy.py

@@ -42,6 +42,7 @@ class ActionModule(object):
         source  = options.get('src', None)
         content = options.get('content', None)
         dest    = options.get('dest', None)
+        force   = utils.boolean(options.get('force', 'yes'))
 
         if (source is None and content is None and not 'first_available_file' in inject) or dest is None:
             result=dict(failed=True, msg="src (or content) and dest are required")
@@ -105,6 +106,10 @@ class ActionModule(object):
             dest = os.path.join(dest, os.path.basename(source))
             remote_md5 = self.runner._remote_md5(conn, tmp, dest)
 
+        # remote_md5 == '0' would mean that the file does not exist.
+        if remote_md5 != '0' and not force:
+            return ReturnData(conn=conn, result=dict(changed=False))
+
         exec_rc = None
         if local_md5 != remote_md5:
 

test/TestRunner.py

@@ -63,12 +63,13 @@ class TestRunner(unittest.TestCase):
         filename = os.path.join(self.stage_dir, filename)
         return filename
 
-    def _run(self, module_name, module_args, background=0):
+    def _run(self, module_name, module_args, background=0, check_mode=False):
         ''' run a module and get the localhost results '''
         self.runner.module_name = module_name
         args = ' '.join(module_args)
         self.runner.module_args = args
         self.runner.background = background
+        self.runner.check = check_mode
         results = self.runner.run()
         # when using nosetests this will only show up on failure
         # which is pretty useful
@@ -117,6 +118,12 @@ class TestRunner(unittest.TestCase):
             "dest=%s" % output,
         ])
         assert result['changed'] is False
+        with open(output, "a") as output_stream:
+            output_stream.write("output file now differs from input")
+        result = self._run('copy',
+                           ["src=%s" % input_, "dest=%s" % output, "force=no"],
+                           check_mode=True)
+        assert result['changed'] is False
 
     def test_command(self):
         # test command module, change trigger, etc