Hurd: fix fdatasync/fsync if the fd does not support file_sync

Handle the case of the fd port implementing a stub (EOPNOTSUPP),
properly returning EINVAL.

2012-10-29  Pino Toscano  <toscano.pino@tiscali.it>

	* sysdeps/mach/hurd/fdatasync.c: Turn ERR into EINVAL if it is
	EOPNOTSUPP.
	* sysdeps/mach/hurd/fsync.c: Likewise.
--- a/sysdeps/mach/hurd/fdatasync.c
+++ b/sysdeps/mach/hurd/fdatasync.c
@@ -26,6 +26,12 @@ fdatasync (int fd)
 {
   error_t err = HURD_DPORT_USE (fd, __file_sync (port, 1, 1));
   if (err)
-    return __hurd_dfail (fd, err);
+    {
+      if (err == EOPNOTSUPP)
+	/* If the file descriptor does not support sync, return EINVAL
+	   as POSIX specifies.  */
+	err = EINVAL;
+      return __hurd_dfail (fd, err);
+    }
   return 0;
 }
--- a/sysdeps/mach/hurd/fsync.c
+++ b/sysdeps/mach/hurd/fsync.c
@@ -27,6 +27,12 @@ fsync (fd)
 {
   error_t err = HURD_DPORT_USE (fd, __file_sync (port, 1, 0));
   if (err)
-    return __hurd_dfail (fd, err);
+    {
+      if (err == EOPNOTSUPP)
+	/* If the file descriptor does not support sync, return EINVAL
+	   as POSIX specifies.  */
+	err = EINVAL;
+      return __hurd_dfail (fd, err);
+    }
   return 0;
 }