Update hurd/hurdselect.c to be more portable.

Summary of changes:
- Use BAD_TYPECHECK to perform type checking in a cleaner way.
  BAD_TYPECHECK is moved into sysdeps/mach/rpc.h to avoid duplication.
- Remove assertions for mach_msg_type_t since those won't work for
  x86_64.
- Update message structs to use mach_msg_type_t directly.
- Use designated initializers.
Message-Id: <ZFa+roan3ioo0ONM@jupiter.tail36e24.ts.net>

1 files changed, 30 insertions, 0 deletions

diff --git a/sysdeps/mach/mach_rpc.h b/sysdeps/mach/mach_rpc.h
new file mode 100644
index 0000000000..152f057ca7
--- /dev/null
+++ b/sysdeps/mach/mach_rpc.h
@@ -0,0 +1,30 @@
+/* Macros for handling Mach RPC messages.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <mach/message.h>
+
+/* Macro used by MIG to cleanly check the type.  */
+#define BAD_TYPECHECK(type, check) __glibc_unlikely (({	\
+  union { mach_msg_type_t t; uint32_t w; } _t, _c;	\
+  _t.t = *(type); _c.t = *(check);_t.w != _c.w; }))
+
+/* TODO: add this assertion for x86_64.  */
+#ifndef __x86_64__
+_Static_assert (sizeof (uint32_t) == sizeof (mach_msg_type_t),
+                "mach_msg_type_t needs to be the same size as uint32_t");
+#endif