From 9f2d41a65fb8671c5746a952c1917da8f2774bc8 Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Wed, 4 Oct 2017 15:21:12 +0900
Subject: [PATCH 1/2] load-fragment: do not create empty array

Originally added in 4589f5bb0a973e9a41be93de06c87072cea4dfb9.
C.f. 8249bb728db6c2abaf12575d661b52571bdc1ab1 and #6746.
---
 src/core/load-fragment.c | 24 ++----------------------
 1 file changed, 2 insertions(+), 22 deletions(-)

diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c
index 2c3783a9f0..5dd1787098 100644
--- a/src/core/load-fragment.c
+++ b/src/core/load-fragment.c
@@ -284,19 +284,7 @@ int config_parse_unit_path_strv_printf(
         assert(u);
 
         if (isempty(rvalue)) {
-                char **empty;
-
-                /* Empty assignment resets the list. As a special rule
-                 * we actually fill in a real empty array here rather
-                 * than NULL, since some code wants to know if
-                 * something was set at all... */
-                empty = new0(char*, 1);
-                if (!empty)
-                        return log_oom();
-
-                strv_free(*x);
-                *x = empty;
-
+                *x = strv_free(*x);
                 return 0;
         }
 
@@ -1968,15 +1956,7 @@ int config_parse_user_group_strv(
         assert(u);
 
         if (isempty(rvalue)) {
-                char **empty;
-
-                empty = new0(char*, 1);
-                if (!empty)
-                        return log_oom();
-
-                strv_free(*users);
-                *users = empty;
-
+                *users = strv_free(*users);
                 return 0;
         }
 

From ac6e8be66ecf57d401fd60c927cf81d522c7a8b9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
Date: Wed, 4 Oct 2017 11:33:30 +0200
Subject: [PATCH 2/2] core: use strv_isempty to check if supplementary_groups
 is empty

With the previous commit, we know that it will be NULL if empty, but
it's safe to always use strv_isempty() in case the code changes
in the future.
---
 src/core/execute.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/core/execute.c b/src/core/execute.c
index e1c2a57cc6..afb11c6fb6 100644
--- a/src/core/execute.c
+++ b/src/core/execute.c
@@ -895,7 +895,7 @@ static int get_supplementary_groups(const ExecContext *c, const char *user,
                 keep_groups = true;
         }
 
-        if (!c->supplementary_groups)
+        if (strv_isempty(c->supplementary_groups))
                 return 0;
 
         /*
@@ -969,7 +969,7 @@ static int enforce_groups(const ExecContext *context, gid_t gid,
         assert(context);
 
         /* Handle SupplementaryGroups= even if it is empty */
-        if (context->supplementary_groups) {
+        if (!strv_isempty(context->supplementary_groups)) {
                 r = maybe_setgroups(ngids, supplementary_gids);
                 if (r < 0)
                         return r;
@@ -4052,7 +4052,7 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) {
 
         fprintf(f, "%sDynamicUser: %s\n", prefix, yes_no(c->dynamic_user));
 
-        if (strv_length(c->supplementary_groups) > 0) {
+        if (!strv_isempty(c->supplementary_groups)) {
                 fprintf(f, "%sSupplementaryGroups:", prefix);
                 strv_fprintf(f, c->supplementary_groups);
                 fputs("\n", f);