Make "Filename too long" return 404 not 500

starlette/staticfiles.py

@@ -2,6 +2,7 @@
 
 import importlib.util
 import os
+import re
 import stat
 import typing
 from email.utils import parsedate
@@ -124,8 +125,17 @@ async def get_response(self, path: str, scope: Scope) -> Response:
             )
         except PermissionError:
             raise HTTPException(status_code=401)
-        except OSError:
-            raise
+        except OSError as ex:
+            # If the filename is too long for the underlying OS to handle, then the
+            # file couldn't possibly exist, so we treat it as "not found", rather than
+            # as as an unknown error that gets propagated.
+            # From testing in a few different POSIX environments, some return
+            # "File name too long" (with a space), while others return
+            # "Filename too long" (without a space). Hence the regex.
+            if re.search(r"File ?name too long", f"{ex}") is not None:
+                raise HTTPException(status_code=404)
+
+            raise ex
 
         if stat_result and stat.S_ISREG(stat_result.st_mode):
             # We have a static file to serve.

tests/test_staticfiles.py

@@ -469,6 +469,21 @@ def test_staticfiles_access_file_as_dir_returns_404(
     assert response.text == "Not Found"
 
 
+def test_staticfiles_filename_too_long_returns_404(
+    tmpdir: Path, test_client_factory: TestClientFactory
+) -> None:
+    routes = [Mount("/", app=StaticFiles(directory=tmpdir), name="static")]
+    app = Starlette(routes=routes)
+    client = test_client_factory(app)
+
+    # The exact filename limit is platform specific (mainly filesystem specific), but,
+    # as of 2024, it appears to be not more than 4096 chars on POSIX systems, so this
+    # test should behave consistently with a filename longer than that.
+    response = client.get(f"/{'a' * 5000}.txt")
+    assert response.status_code == 404
+    assert response.text == "Not Found"
+
+
 def test_staticfiles_unhandled_os_error_returns_500(
     tmpdir: Path,
     test_client_factory: TestClientFactory,