From 73434f4003c47b5097b195a26a8dbc0d4450a78c Mon Sep 17 00:00:00 2001
From: Michael Kerrisk <mtk.manpages@gmail.com>
Date: Thu, 12 Aug 2021 03:11:13 +0200
Subject: [PATCH] open.2: Explicitly describe the EBADF error that can occur
 with openat()

In particular, specifying an invalid file descriptor number
in 'dirfd' can be used as a check that 'pathname' is absolute.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
---
 man2/open.2 | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/man2/open.2 b/man2/open.2
index 711fd96b8..bfc1b2f6b 100644
--- a/man2/open.2
+++ b/man2/open.2
@@ -966,6 +966,19 @@ must be a directory that was opened for reading
 or using the
 .B O_PATH
 flag.
+.PP
+If the pathname given in
+.I pathname
+is relative, and
+.I dirfd
+is not a valid file descriptor, an error
+.RB ( EBADF )
+results.
+(Specifying an invalid file descriptor number in
+.I dirfd
+can be used as a means to ensure that
+.I pathname
+is absolute.)
 .\"
 .SS openat2(2)
 The