[newlib 50/65] ioccom: define ioctl cmd value that can never be valid

[Sebastian Huber]

From: Konstantin Belousov <kib at FreeBSD.org>

Its use is for cases where some filler is needed for cmd, or we need an
indication that there were no cmd supplied, and so on.

Reviewed by:	jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D29935
---
 newlib/libc/sys/rtems/include/sys/ioccom.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/newlib/libc/sys/rtems/include/sys/ioccom.h b/newlib/libc/sys/rtems/include/sys/ioccom.h
index adaa30797..7b78db8e9 100644
--- a/newlib/libc/sys/rtems/include/sys/ioccom.h
+++ b/newlib/libc/sys/rtems/include/sys/ioccom.h
@@ -84,6 +84,9 @@ typedef unsigned long ioctl_command_t;
 #define	IOCPARM_IVAL(x)	((int)(intptr_t)(void *)*(caddr_t *)(void *)(x))
 #endif
 
+#define	_IOC_INVALID	(_IOC_VOID|_IOC_INOUT)	/* Never valid cmd value,
+						   use as filler */
+
 #endif
 
 __BEGIN_DECLS
-- 
2.35.3