[PATCH v2 1/2] include/uapi: Define AT_ABSOLUTE to allow only absolute paths

[Steven Stewart-Gallus <sstewartgallus00@mylangara.bc.ca>]

This way people can use existing functionality (passing an invalid value
for dirfd to allow only absolute paths in *at style functions) and be
compatible for the future if Linux ever adds in new AT_* flags.

Signed-off-by: Steven Stewart-Gallus <sstewartgallus00@mylangara.bc.ca>
---
 include/uapi/linux/fcntl.h |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
index 074b886..c4c5705 100644
--- a/include/uapi/linux/fcntl.h
+++ b/include/uapi/linux/fcntl.h
@@ -38,9 +38,16 @@
 #define DN_ATTRIB	0x00000020	/* File changed attibutes */
 #define DN_MULTISHOT	0x80000000	/* Don't remove notifier */
 
+#define AT_FDABSOLUTE		-1      /* Special value used to indicate
+					   openat should not use any directory
+					   and only accept absolute values.
+					   Currently, other values work for this
+					   but in the future that might
+					   change. */
 #define AT_FDCWD		-100    /* Special value used to indicate
-                                           openat should use the current
-                                           working directory. */
+					   openat should use the current
+					   working directory. */
+
 #define AT_SYMLINK_NOFOLLOW	0x100   /* Do not follow symbolic links.  */
 #define AT_REMOVEDIR		0x200   /* Remove directory instead of
                                            unlinking file.  */
-- 
1.7.9.5