From d0968b783128667b1db0e97d6774a0a1f15fa152 Mon Sep 17 00:00:00 2001
From: Alan Jenkins <alan.christopher.jenkins@gmail.com>
Date: Mon, 21 Aug 2017 11:49:25 +0100
Subject: [PATCH] logind: add missing check for conflicting operation v.s.
 scheduled shutdown

> We don't want to shutdown while a suspend is running, and vice versa.
> This would be confusing and could lead to data loss in the worst case.

https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1441253/comments/4

According to the above comment, if the conflicting operation is hung,
we don't want to force things when the admin has not passed a force option.

Similarly if you're not an admin, you probably shouldn't get to sneak
around this check by using a scheduled shutdown instead of an unscheduled
one.  (And no-one so far thought it necessary to add such a permission in
PolKit).

Note that if the conflicting operation was _not_ hung, and we lost the
race with suspend, the system might not have shut down at the scheduled
time anyway.  Which is no good if you were scheduling a power outage.
And scheduling a shutdown for an arbitrary time when the system is resumed,
does not seem a very useful semantic.  More likely, scheduled shutdowns are
useful on systems which do not use suspend, such as multi-user servers.
(In which case even PolKit defaults likely don't let the users trigger
suspend).

(cherry picked from commit b498d6ea9f72520c579035928d16c527d992bca8)
---
 src/login/logind-dbus.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/login/logind-dbus.c b/src/login/logind-dbus.c
index f0943e56e0..3f05c86f5c 100644
--- a/src/login/logind-dbus.c
+++ b/src/login/logind-dbus.c
@@ -1946,9 +1946,15 @@ static int manager_scheduled_shutdown_handler(
         else
                 target = SPECIAL_REBOOT_TARGET;
 
-        r = execute_shutdown_or_sleep(m, 0, target, &error);
+        /* Don't allow multiple jobs being executed at the same time */
+        if (m->action_what) {
+                log_error("Scheduled shutdown to %s failed: shutdown or sleep operation already in progress", target);
+                return -EALREADY;
+        }
+
+        r = execute_shutdown_or_sleep(m, INHIBIT_SHUTDOWN, target, &error);
         if (r < 0)
-                return log_error_errno(r, "Unable to execute transition to %s: %m", target);
+                return log_error_errno(r, "Scheduled shutdown to %s failed: %m", target);
 
         return 0;
 }