From a11334f0eae67b5159a416193e2e37634281000a Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 8 Nov 2018 09:33:31 +0100
Subject: [PATCH] unit: make UNIT() cast function deal with NULL pointers

Fixes: #10681
(cherry picked from commit bbf11206230d1b089118971f98a047151cb5c4fa)

Related: #1871827
---
 src/core/unit.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/core/unit.h b/src/core/unit.h
index 6e37fd6f5a..ec45b5fb48 100644
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -597,7 +597,12 @@ extern const UnitVTable * const unit_vtable[_UNIT_TYPE_MAX];
         }
 
 /* For casting the various unit types into a unit */
-#define UNIT(u) (&(u)->meta)
+#define UNIT(u)                                         \
+        ({                                              \
+                typeof(u) _u_ = (u);                    \
+                Unit *_w_ = _u_ ? &(_u_)->meta : NULL;  \
+                _w_;                                    \
+        })
 
 #define UNIT_HAS_EXEC_CONTEXT(u) (UNIT_VTABLE(u)->exec_context_offset > 0)
 #define UNIT_HAS_CGROUP_CONTEXT(u) (UNIT_VTABLE(u)->cgroup_context_offset > 0)