From 7787e7eed9d2a43fb6eb66666040f1b495995a2f Mon Sep 17 00:00:00 2001
From: Chuck Silvers <chs@FreeBSD.org>
Date: Mon, 1 Feb 2021 16:21:14 -0800
Subject: [PATCH] tail: fix "tail -F" file rotation detection

When checking if the newly opened file is the same as the old one,
we need to fstat() the new file descriptor, not the old one again.

Reviewed by:	glebius
Sponsored by:	Netflix
---
 usr.bin/tail/forward.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/usr.bin/tail/forward.c b/usr.bin/tail/forward.c
index 2888bd18816e..878cb5a4550b 100644
--- a/usr.bin/tail/forward.c
+++ b/usr.bin/tail/forward.c
@@ -367,7 +367,7 @@ follow(file_info_t *files, enum STYLE style, off_t off)
 					continue;
 				ftmp = fileargs_fopen(fa, file->file_name, "r");
 				if (ftmp == NULL ||
-				    fstat(fileno(file->fp), &sb2) == -1) {
+				    fstat(fileno(ftmp), &sb2) == -1) {
 					if (errno != ENOENT)
 						ierr(file->file_name);
 					show(file);