Support testing from read-only filesystems

1 files changed, 9 insertions, 0 deletions

diff --git a/sphinx/testing/path.py b/sphinx/testing/path.py
index a37839d60..1872f2577 100644
--- a/sphinx/testing/path.py
+++ b/sphinx/testing/path.py
@@ -98,6 +98,15 @@ class path(str):
             pointed to by the symbolic links are copied.
         """
         shutil.copytree(self, destination, symlinks=symlinks)
+        # If source tree is marked read-only (e.g. because it is on a read-only
+        # filesystem), `shutil.copytree` will mark the destination as read-only
+        # as well.  To avoid failures when adding additional files/directories
+        # to the destination tree, ensure destination directories are not marked
+        # read-only.
+        for root, dirs, files in os.walk(destination):
+            os.chmod(root, 0o755)
+            for name in files:
+                os.chmod(os.path.join(root, name), 0o644)
 
     def movetree(self, destination: str) -> None:
         """