bpo-28684: asyncio tests handle PermissionError raised on binding unix sockets (GH-4503)

The test.support.skip_unless_bind_unix_socket() decorator is used to skip
asyncio tests that fail because the platform lacks a functional bind()
function for unix domain sockets (as it is the case for non root users on the
recent Android versions that run now SELinux in enforcing mode).

1 files changed, 23 insertions, 0 deletions

diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py
index b7cbdc6..e864896 100644
--- a/Lib/test/support/__init__.py
+++ b/Lib/test/support/__init__.py
@@ -88,6 +88,7 @@ __all__ = [
     "requires_IEEE_754", "skip_unless_xattr", "requires_zlib",
     "anticipate_failure", "load_package_tests", "detect_api_mismatch",
     "check__all__", "requires_android_level", "requires_multiprocessing_queue",
+    "skip_unless_bind_unix_socket",
     # sys
     "is_jython", "is_android", "check_impl_detail", "unix_shell",
     "setswitchinterval",
@@ -2432,6 +2433,28 @@ def skip_unless_xattr(test):
     msg = "no non-broken extended attribute support"
     return test if ok else unittest.skip(msg)(test)
 
+_bind_nix_socket_error = None
+def skip_unless_bind_unix_socket(test):
+    """Decorator for tests requiring a functional bind() for unix sockets."""
+    if not hasattr(socket, 'AF_UNIX'):
+        return unittest.skip('No UNIX Sockets')(test)
+    global _bind_nix_socket_error
+    if _bind_nix_socket_error is None:
+        path = TESTFN + "can_bind_unix_socket"
+        with socket.socket(socket.AF_UNIX) as sock:
+            try:
+                sock.bind(path)
+                _bind_nix_socket_error = False
+            except OSError as e:
+                _bind_nix_socket_error = e
+            finally:
+                unlink(path)
+    if _bind_nix_socket_error:
+        msg = 'Requires a functional unix bind(): %s' % _bind_nix_socket_error
+        return unittest.skip(msg)(test)
+    else:
+        return test
+
 
 def fs_is_case_insensitive(directory):
     """Detects if the file system for the specified directory is case-insensitive."""