[lxc-devel] [lxc/master] lxccontainer: improve shutdown signal detection

[brauner on Github]

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From 4b6037da98634608d8b2f4833bf9e3a79fabb267 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brauner at ubuntu.com>
Date: Tue, 12 Mar 2019 15:06:10 +0100
Subject: [PATCH] lxccontainer: improve shutdown signal detection

According to Lennart the official way of detecting whether systemd is runnig is
to check for the existence of /run/systemd/system.

Signed-off-by: Christian Brauner <christian.brauner at ubuntu.com>
---
 src/lxc/lxccontainer.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
index cba46092fe..6b094cc25e 100644
--- a/src/lxc/lxccontainer.c
+++ b/src/lxc/lxccontainer.c
@@ -2084,7 +2084,9 @@ static bool do_lxcapi_shutdown(struct lxc_container *c, int timeout)
 	/* Detect whether we should send SIGRTMIN + 3 (e.g. systemd). */
 	if (c->lxc_conf && c->lxc_conf->haltsignal)
 		haltsignal = c->lxc_conf->haltsignal;
-	else if (task_blocks_signal(pid, (SIGRTMIN + 3)))
+	else if ((faccessat(AT_FDCWD, "/run/systemd/system/", F_OK,
+			    AT_SYMLINK_NOFOLLOW) == 0) ||
+		 task_blocks_signal(pid, (SIGRTMIN + 3)))
 		haltsignal = (SIGRTMIN + 3);
 
 	/* Add a new state client before sending the shutdown signal so that we