Add file_exists check to file_clone (#271)

Add file_exists check to file_clone
Safeguard clone operation, that failed due to overwrite flag was set, but no file exists.
The api fails if the file does not exists and the overwrite flag is set.
The fix is checking the dest directory if the file exists, it sets the flag, but if not, that omits setting it.
Change-Id: I87c21c6b3962b590af1e636f54988d990994dec0

Author: Scsabiii

cinder/tests/unit/volume/drivers/netapp/dataontap/client/test_client_cmode_rest.py

@@ -2345,6 +2345,8 @@ def test_clone_file_snapshot(self, overwrite_dest):
                          return_value=fake_volume)
         self.mock_object(self.client.connection, 'get_api_version',
                          return_value=api_version)
+        self.mock_object(self.client, 'file_exists',
+                         return_vaule=True)
 
         self.client.clone_file(
             fake_volume['name'], fake_name, fake_new_name, fake.VSERVER_NAME,

cinder/volume/drivers/netapp/dataontap/client/client_cmode_rest.py

@@ -1690,6 +1690,25 @@ def move_lun(self, path, new_path):
         }
         self.send_request('/storage/luns/', 'patch', query=query, body=body)
 
+    def file_exists(self, netapp_vol, file_path):
+
+        file_found = False
+        info_fields = {'type': 'file'}
+        file_elements = file_path.split('/')
+        if len(file_elements) == 1:
+            dir_path = ''
+        else:
+            dir_path = '/'.join(file_elements[:-1])
+        dir_path.replace('.', '%2E').replace('/', '%2F')
+        file_name = file_elements[-1]
+        query = f'/storage/volumes/{netapp_vol["uuid"]}/files/{dir_path}'
+        file_info = self.send_request(query, 'get', body=info_fields)
+        for file in file_info['records']:
+            if file['name'] == file_name:
+                file_found = True
+
+        return file_found
+
     def clone_file(self, flex_vol, src_path, dest_path, vserver,
                    dest_exists=False, source_snapshot=None, is_snapshot=False):
         """Clones file on vserver."""
@@ -1716,7 +1735,7 @@ def clone_file(self, flex_vol, src_path, dest_path, vserver,
         if is_snapshot and self.features.BACKUP_CLONE_PARAM:
             body['is_backup'] = True
 
-        if dest_exists:
+        if dest_exists and self.file_exists(volume, dest_path):
             body['overwrite_destination'] = True
 
         self.send_request('/storage/file/clone', 'post', body=body)