Use ensuredir() instead of os.makedirs() to fix race conditions

Use the ensuredir() function consistently across Sphinx code to avoid
race conditions e.g. when multiple Sphinx instances attempt to create
the same output directory. The ensuredir() function that was already
present in sphinx.util.osutil correctly catches EEXIST exception that
occurs if the specified directory already exists (i.e. it was created
between the call to os.path.isdir() and os.makedirs() that follows it).

While at it, remove redundant os.path.isdir() calls when they only
guarded the os.makedirs() call, and replace mkdir_p() which had pretty
much the same purpose, except for being prone to race conditions.

I did not modify testing-related code as race conditions mostly affect
real applications and not the test environment.

Fix #4281: Race conditions when creating output directory

1 files changed, 2 insertions, 2 deletions

diff --git a/sphinx/application.py b/sphinx/application.py
index 0d6d3d0b3..b5705face 100644
--- a/sphinx/application.py
+++ b/sphinx/application.py
@@ -41,7 +41,7 @@ from sphinx.util import import_object
 from sphinx.util import logging
 from sphinx.util import status_iterator, old_status_iterator, display_chunk
 from sphinx.util.tags import Tags
-from sphinx.util.osutil import ENOENT
+from sphinx.util.osutil import ENOENT, ensuredir
 from sphinx.util.console import bold, darkgreen  # type: ignore
 from sphinx.util.docutils import is_html5_writer_available, directive_helper
 from sphinx.util.i18n import find_catalog_source_files
@@ -160,7 +160,7 @@ class Sphinx(object):
 
         if not path.isdir(outdir):
             logger.info('making output directory...')
-            os.makedirs(outdir)
+            ensuredir(outdir)
 
         # read config
         self.tags = Tags(tags)