[PATCH glibc] Update hurd/intr-msg.c to be more portable

[Flavio Cruz]

Summary of the changes:
- Introduce BAD_TYPECHECK from MiG to make it simpler to do type
  checking.
- Replace int type with mach_msg_type_t. This assumes that
  mach_msg_type_t is always the same size as int which is not true for
  x86_64.
- Calculate the size and align using PTR_ALIGN_UP, which is a bit
  cleaner and similar to what we do elsewhere.
- Define mach_msg_type_t to check using designated initializers.
---
 hurd/intr-msg.c | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/hurd/intr-msg.c b/hurd/intr-msg.c
index 716d87ab6a..a8e4d04041 100644
--- a/hurd/intr-msg.c
+++ b/hurd/intr-msg.c
@@ -28,6 +28,11 @@
 # define mig_reply_header_t    mig_reply_error_t
 #endif
 
+/* 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; }))
+
 error_t
 _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
                         mach_msg_option_t option,
@@ -61,7 +66,7 @@ _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
 #ifdef NDR_CHAR_ASCII
       NDR_record_t ndr;
 #else
-      int type;
+      mach_msg_type_t type;
 #endif
       int code;
     } check;
@@ -222,11 +227,12 @@ _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
 
              if (ty->msgtl_header.msgt_inline)
                {
+                 /* Calculate length of data in bytes.  */
+                 const vm_size_t length = ((number * size) + 7) >> 3;
                  clean_ports ((void *) ty, 0);
-                 /* calculate length of data in bytes, rounding up */
-                 ty = (void *) ty + (((((number * size) + 7) >> 3)
-                                      + sizeof (mach_msg_type_t) - 1)
-                                     &~ (sizeof (mach_msg_type_t) - 1));
+                 /* Move to the next argument.  */
+                 ty = (void *) PTR_ALIGN_UP ((char *) ty + length,
+                     __alignof__ (uintptr_t));
                }
              else
                {
@@ -354,19 +360,21 @@ _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
       {
        /* We got a reply.  Was it EINTR?  */
 #ifdef MACH_MSG_TYPE_BIT
-       const union
-       {
-         mach_msg_type_t t;
-         int i;
-       } check =
-         { t: { MACH_MSG_TYPE_INTEGER_T, sizeof (integer_t) * 8,
-                1, TRUE, FALSE, FALSE, 0 } };
+       static const mach_msg_type_t type_check = {
+         .msgt_name = MACH_MSG_TYPE_INTEGER_T,
+         .msgt_size = sizeof (integer_t) * 8,
+         .msgt_number = 1,
+         .msgt_inline = TRUE,
+         .msgt_longform = FALSE,
+         .msgt_deallocate = FALSE,
+         .msgt_unused = 0
+       };
 #endif
 
         if (m->reply.RetCode == EINTR
            && m->header.msgh_size == sizeof m->reply
 #ifdef MACH_MSG_TYPE_BIT
-           && m->check.type == check.i
+           && !BAD_TYPECHECK(&m->check.type, &type_check)
 #endif
            && !(m->header.msgh_bits & MACH_MSGH_BITS_COMPLEX))
          {
-- 
2.39.2