Safely generate os-faults file to temporary files

Change-Id: If1031a6d600958409d7b505753abdb4feb11a15a

tobiko/__init__.py

@@ -57,6 +57,7 @@ load_object = loader_manager.load_object
 load_module = loader_manager.load_module
 
 makedirs = _os.makedirs
+open_output_file = _os.open_output_file
 
 discover_testcases = testcase_manager.discover_testcases
 

tobiko/common/_exception.py

@@ -93,12 +93,14 @@ class ExceptionInfo(collections.namedtuple('ExceptionInfo',
 
     def __exit__(self, _type, _value, _traceback):
         if self.reraise_on_exit:
-            LOG.exception("Exception occurred while handling %s(%s) "
-                          "exception.", _type, _value)
+            if _type is not None:
+                LOG.exception("Exception occurred while handling %s(%s) "
+                              "exception.", self.type, self.value)
             self.reraise()
 
     def reraise(self):
-        six.reraise(*self)
+        if self.type is not None:
+            six.reraise(*self)
 
 
 def exc_info(reraise=True):

tobiko/common/_os.py

@@ -13,11 +13,15 @@
 #    under the License.
 from __future__ import absolute_import
 
+import contextlib
 import os
+import tempfile
 
 from oslo_log import log
 
 
+from tobiko.common import _exception
+
 LOG = log.getLogger(__name__)
 
 
@@ -33,3 +37,22 @@ def makedirs(name, mode=0o777, exist_ok=True):
     except Exception:
         if not exist_ok or not os.path.isdir(name):
             raise
+
+
+@contextlib.contextmanager
+def open_output_file(filename, mode='w', temp_dir=None, text=False):
+    basename = os.path.basename(filename)
+    prefix, suffix = os.path.splitext(basename)
+    prefix += '-'
+    temp_fd, temp_filename = tempfile.mkstemp(prefix=prefix,
+                                              suffix=suffix,
+                                              dir=temp_dir,
+                                              text=text)
+    try:
+        with os.fdopen(temp_fd, mode) as temp_stream:
+            yield temp_stream
+        os.rename(temp_filename, filename)
+    finally:
+        with _exception.exc_info():
+            if os.path.isfile(temp_filename):
+                os.remove(temp_filename)

tobiko/openstack/os_faults/_config_file.py

@@ -137,7 +137,7 @@ class OsFaultsConfigFileFixture(tobiko.SharedFixture):
             services=self.list_services(),
             containers=self.list_containers(),
             proxy=None)
-        with open(config_filename, "w") as f:
+        with tobiko.open_output_file(config_filename) as f:
             f.write(config_content)
         return config_filename