From 57cd391d21ff8ad805c6d7bd1fbc9d5b37943fe9 Mon Sep 17 00:00:00 2001
From: jhb <jhb@FreeBSD.org>
Date: Sat, 10 Jun 2017 01:20:08 +0000
Subject: [PATCH] Improve decoding of RB_AUTOBOOT in the 'howto' argument to
 reboot().

The reboot() system call accepts a mode (RB_AUTOBOOT, RB_HALT, RB_POWEROFF,
or RB_REROOT) as well as zero or more optional flags in 'howto'.
However, RB_AUTOBOOT was only displayed if 'howto' was exactly 0.
Combinations like 'RB_AUTOBOOT | RB_DUMP' were decoded as 'RB_DUMP'.
Instead, imply that RB_AUTOBOOT was specified if none of the other "mode"
flags were specified.
---
 lib/libsysdecode/flags.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/lib/libsysdecode/flags.c b/lib/libsysdecode/flags.c
index bf0319f5dcaf..eb28820a0365 100644
--- a/lib/libsysdecode/flags.c
+++ b/lib/libsysdecode/flags.c
@@ -634,8 +634,19 @@ sysdecode_quotactl_cmd(FILE *fp, int cmd)
 bool
 sysdecode_reboot_howto(FILE *fp, int howto, int *rem)
 {
+	bool printed;
 
-	return (print_mask_int(fp, rebootopt, howto, rem));
+	/*
+	 * RB_AUTOBOOT is special in that its value is zero, but it is
+	 * also an implied argument if a different operation is not
+	 * requested via RB_HALT, RB_POWEROFF, or RB_REROOT.
+	 */
+	if (howto != 0 && (howto & (RB_HALT | RB_POWEROFF | RB_REROOT)) == 0) {
+		fputs("RB_AUTOBOOT|", fp);
+		printed = true;
+	} else
+		printed = false;
+	return (print_mask_int(fp, rebootopt, howto, rem) || printed);
 }
 
 bool