sandbox: add flags for open() call

This provides a way for callers to create files for writing. The flags
are translated at runtime, for the ones we support.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

include/os.h

@@ -1,4 +1,9 @@
 /*
+ * Operating System Interface
+ *
+ * This provides access to useful OS routines for the sandbox architecture.
+ * They are kept in a separate file so we can include system headers.
+ *
  * Copyright (c) 2011 The Chromium OS Authors.
  * See file CREDITS for list of people who contributed to this
  * project.
@@ -19,12 +24,6 @@
  * MA 02111-1307 USA
  */
 
-/*
- * Operating System Interface
- *
- * This provides access to useful OS routines from the sandbox architecture
- */
-
 #ifndef __OS_H__
 #define __OS_H__
 
@@ -72,6 +71,12 @@ off_t os_lseek(int fd, off_t offset, int whence);
  */
 int os_open(const char *pathname, int flags);
 
+#define OS_O_RDONLY	0
+#define OS_O_WRONLY	1
+#define OS_O_RDWR	2
+#define OS_O_MASK	3	/* Mask for read/write flags */
+#define OS_O_CREAT	0100
+
 /**
  * Access to the OS close() system call
  *