use stat module instead of checksum code

- added new function for action plugins this avoids the very fragile checksum code that is shell dependant.
- ported copy module to it
- converted assemble to new stat function
- some corrections and ported temlpate
- updated old checksum function to use new stat one under the hood
- documented revamped remote checksum method

lib/ansible/plugins/action/__init__.py

@@ -291,28 +291,54 @@ class ActionBase(with_metaclass(ABCMeta, object)):
         res = self._low_level_execute_command(cmd, sudoable=sudoable)
         return res
 
-    def _remote_checksum(self, path, all_vars):
+    def _execute_remote_stat(self, path, all_vars, follow):
         '''
-        Takes a remote checksum and returns 1 if no file
+        Get information from remote file.
         '''
+        module_args=dict(
+           path=path,
+           follow=follow,
+           get_md5=False,
+           get_checksum=True,
+           checksum_algo='sha1',
+        )
+        mystat = self._execute_module(module_name='stat', module_args=module_args, task_vars=all_vars)
+
+        if 'failed' in mystat and mystat['failed']:
+            raise AnsibleError('Failed to get information on remote file (%s): %s' % (path, mystat['msg']))
+
+        if not mystat['stat']['exists']:
+            # empty might be matched, 1 should never match, also backwards compatible
+            mystat['stat']['checksum'] = '1'
 
-        python_interp = all_vars.get('ansible_python_interpreter', 'python')
+        return mystat['stat']
 
-        cmd = self._connection._shell.checksum(path, python_interp)
-        data = self._low_level_execute_command(cmd, sudoable=True)
+    def _remote_checksum(self, path, all_vars):
+        '''
+        Produces a remote checksum given a path,
+        Returns a number 0-4 for specific errors instead of checksum, also ensures it is different
+        0 = unknown error
+        1 = file does not exist, this might not be an error
+        2 = permissions issue
+        3 = its a directory, not a file
+        4 = stat module failed, likely due to not finding python
+        '''
+        x = "0" # unknown error has occured
         try:
-            data2 = data['stdout'].strip().splitlines()[-1]
-            if data2 == u'':
-                # this may happen if the connection to the remote server
-                # failed, so just return "INVALIDCHECKSUM" to avoid errors
-                return "INVALIDCHECKSUM"
+            remote_stat = self._execute_remote_stat(path, all_vars, follow=False)
+            if remote_stat['exists'] and remote_stat['isdir']:
+                x = "3" # its a directory not a file
             else:
-                return data2.split()[0]
-        except IndexError:
-            display.warning(u"Calculating checksum failed unusually, please report this to "
-                u"the list so it can be fixed\ncommand: %s\n----\noutput: %s\n----\n" % (to_unicode(cmd), data))
-            # this will signal that it changed and allow things to keep going
-            return "INVALIDCHECKSUM"
+                x = remote_stat['checksum'] # if 1, file is missing
+        except AnsibleError as e:
+            errormsg = to_bytes(e)
+            if errormsg.endswith('Permission denied'):
+                x = "2" # cannot read file
+            elif errormsg.endswith('MODULE FAILURE'):
+                x = "4" # python not found or module uncaught exception
+        finally:
+            return x
+
 
     def _remote_expand_user(self, path):
         ''' takes a remote path and performs tilde expansion on the remote host '''

lib/ansible/plugins/action/assemble.py

@@ -89,6 +89,7 @@ class ActionModule(ActionBase):
         delimiter  = self._task.args.get('delimiter', None)
         remote_src = self._task.args.get('remote_src', 'yes')
         regexp     = self._task.args.get('regexp', None)
+        follow     = self._task.args.get('follow', False)
         ignore_hidden = self._task.args.get('ignore_hidden', False)
 
         if src is None or dest is None:
@@ -119,10 +120,10 @@ class ActionModule(ActionBase):
 
         path_checksum = checksum_s(path)
         dest = self._remote_expand_user(dest)
-        remote_checksum = self._remote_checksum(dest, all_vars=task_vars)
+        dest_stat = self._execute_remote_stat(dest, all_vars=task_vars, follow=follow)
 
         diff = {}
-        if path_checksum != remote_checksum:
+        if path_checksum != dest_stat['checksum']:
             resultant = file(path).read()
 
             if self._play_context.diff:

lib/ansible/plugins/action/copy.py

@@ -46,6 +46,7 @@ class ActionModule(ActionBase):
         force   = boolean(self._task.args.get('force', 'yes'))
         faf     = self._task.first_available_file
         remote_src = boolean(self._task.args.get('remote_src', False))
+        follow  = boolean(self._task.args.get('follow', False))
 
         if (source is None and content is None and faf is None) or dest is None:
             result['failed'] = True
@@ -167,11 +168,11 @@ class ActionModule(ActionBase):
             else:
                 dest_file = self._connection._shell.join_path(dest)
 
-            # Attempt to get the remote checksum
-            remote_checksum = self._remote_checksum(dest_file, all_vars=task_vars)
+            # Attempt to get remote file info
+            dest_status = self._execute_remote_stat(dest_file, all_vars=task_vars, follow=follow)
 
-            if remote_checksum == '3':
-                # The remote_checksum was executed on a directory.
+            if dest_status['exists'] and dest_status['isdir']:
+                # The dest is a directory.
                 if content is not None:
                     # If source was defined as content remove the temporary file and fail out.
                     self._remove_tempfile_if_content_defined(content, content_tempfile)
@@ -179,15 +180,15 @@ class ActionModule(ActionBase):
                     result['msg'] = "can not use content with a dir as dest"
                     return result
                 else:
-                    # Append the relative source location to the destination and retry remote_checksum
+                    # Append the relative source location to the destination and get remote stats again
                     dest_file = self._connection._shell.join_path(dest, source_rel)
-                    remote_checksum = self._remote_checksum(dest_file, all_vars=task_vars)
+                    dest_status = self._execute_remote_stat(dest_file, all_vars=task_vars, follow=follow)
 
-            if remote_checksum != '1' and not force:
+            if not dest_status['exists'] and not force:
                 # remote_file does not exist so continue to next iteration.
                 continue
 
-            if local_checksum != remote_checksum:
+            if local_checksum != dest_status['checksum']:
                 # The checksums don't match and we will change or error out.
                 changed = True
 

lib/ansible/plugins/action/template.py

@@ -34,23 +34,18 @@ class ActionModule(ActionBase):
     TRANSFERS_FILES = True
 
     def get_checksum(self, dest, all_vars, try_directory=False, source=None):
-        remote_checksum = self._remote_checksum(dest, all_vars=all_vars)
+        try:
+            dest_stat = self._execute_remote_stat(dest, all_vars=all_vars, follow=False)
 
-        if remote_checksum in ('0', '2', '3', '4'):
-            # Note: 1 means the file is not present which is fine; template
-            # will create it.  3 means directory was specified instead of file
-            if try_directory and remote_checksum == '3' and source:
+            if dest_stat['exists'] and dest_stat['isdir'] and try_directory and source:
                 base = os.path.basename(source)
                 dest = os.path.join(dest, base)
-                remote_checksum = self.get_checksum(dest, all_vars=all_vars, try_directory=False)
-                if remote_checksum not in ('0', '2', '3', '4'):
-                    return remote_checksum
+                dest_stat = self._execute_remote_stat(dest, all_vars=all_vars, follow=False)
 
-            result = dict(failed=True, msg="failed to checksum remote file."
-                        " Checksum error code: %s" % remote_checksum)
-            return result
+        except Exception as e:
+            return dict(failed=True, msg=to_bytes(e))
 
-        return remote_checksum
+        return dest_stat['checksum']
 
     def run(self, tmp=None, task_vars=None):
         ''' handler for template operations '''