From 7ecc424fbec9ce254655dcfd742463e849d07378 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 29 Jul 2021 21:05:38 +0200
Subject: [PATCH 1/2] alloc-util: drop double eval from free_and_replace()

Inspired by: 2744c7bb0176dc6b86a69acd4c449ea9e269e097
---
 src/basic/alloc-util.h | 8 +++++---
 src/basic/strv.h       | 8 +++++---
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/basic/alloc-util.h b/src/basic/alloc-util.h
index 3c33308f48..0af425e491 100644
--- a/src/basic/alloc-util.h
+++ b/src/basic/alloc-util.h
@@ -51,9 +51,11 @@ static inline void *mfree(void *memory) {
 
 #define free_and_replace(a, b)                  \
         ({                                      \
-                free(a);                        \
-                (a) = (b);                      \
-                (b) = NULL;                     \
+                typeof(a)* _a = &(a);           \
+                typeof(b)* _b = &(b);           \
+                free(*_a);                      \
+                (*_a) = (*_b);                  \
+                (*_b) = NULL;                   \
                 0;                              \
         })
 
diff --git a/src/basic/strv.h b/src/basic/strv.h
index 911528fab4..e7654c0c0f 100644
--- a/src/basic/strv.h
+++ b/src/basic/strv.h
@@ -233,9 +233,11 @@ int fputstrv(FILE *f, char * const *l, const char *separator, bool *space);
 
 #define strv_free_and_replace(a, b)             \
         ({                                      \
-                strv_free(a);                   \
-                (a) = (b);                      \
-                (b) = NULL;                     \
+                char ***_a = &(a);              \
+                char ***_b = &(b);              \
+                strv_free(*_a);                 \
+                (*_a) = (*_b);                  \
+                (*_b) = NULL;                   \
                 0;                              \
         })
 

From 0ddd5e547e3d4c701a506d5c62cb6547e2d72721 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 29 Jul 2021 21:13:03 +0200
Subject: [PATCH 2/2] xdg-autostart-service: rely on the new double-eval-free
 free_and_replace()

These semi-reverts 2744c7bb0176dc6b86a69acd4c449ea9e269e097
---
 src/xdg-autostart-generator/xdg-autostart-service.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/xdg-autostart-generator/xdg-autostart-service.c b/src/xdg-autostart-generator/xdg-autostart-service.c
index f21d3f54b1..501cdca0b6 100644
--- a/src/xdg-autostart-generator/xdg-autostart-service.c
+++ b/src/xdg-autostart-generator/xdg-autostart-service.c
@@ -416,8 +416,7 @@ int xdg_autostart_format_exec_start(
                         if (!escaped)
                                 return log_oom();
 
-                        free_and_replace(exec_split[n], escaped);
-                        n++;
+                        free_and_replace(exec_split[n++], escaped);
                         continue;
                 }
 
@@ -457,8 +456,7 @@ int xdg_autostart_format_exec_start(
                 if (!quoted)
                         return log_oom();
 
-                free_and_replace(exec_split[n], quoted);
-                n++;
+                free_and_replace(exec_split[n++], quoted);
         }
         for (; exec_split[n]; n++)
                 exec_split[n] = mfree(exec_split[n]);