Replace strdup_or_null() by strdup_to()

I didn't know that this helper existed… It is very similar to strdup_to_full(),
but all callers can actually be replaced by strdup_to(), which has more fitting
semantics.

src/basic/string-util.h

@@ -303,25 +303,4 @@ bool version_is_valid_versionspec(const char *s);
 
 ssize_t strlevenshtein(const char *x, const char *y);
 
-static inline int strdup_or_null(const char *s, char **ret) {
-        char *c;
-
-        assert(ret);
-
-        /* This is a lot like strdup(), but is happy with NULL strings, and does not treat that as error, but
-         * copies the NULL value. */
-
-        if (!s) {
-                *ret = NULL;
-                return 0;
-        }
-
-        c = strdup(s);
-        if (!c)
-                return -ENOMEM;
-
-        *ret = c;
-        return 1;
-}
-
 char *strrstr(const char *haystack, const char *needle);

src/core/unit.c

@@ -5338,7 +5338,7 @@ int unit_set_exec_params(Unit *u, ExecParameters *p) {
 
         p->runtime_scope = u->manager->runtime_scope;
 
-        r = strdup_or_null(manager_get_confirm_spawn(u->manager), &p->confirm_spawn);
+        r = strdup_to(&p->confirm_spawn, manager_get_confirm_spawn(u->manager));
         if (r < 0)
                 return r;
 

src/fstab-generator/fstab-generator.c

@@ -498,13 +498,8 @@ static int mandatory_mount_drop_unapplicable_options(
         assert(where);
         assert(ret_options);
 
-        if (!(*flags & (MOUNT_NOAUTO|MOUNT_NOFAIL|MOUNT_AUTOMOUNT))) {
-                r = strdup_or_null(options, ret_options);
-                if (r < 0)
-                        return r;
-
-                return 0;
-        }
+        if (!(*flags & (MOUNT_NOAUTO|MOUNT_NOFAIL|MOUNT_AUTOMOUNT)))
+                return strdup_to(ret_options, options);
 
         log_debug("Mount '%s' is mandatory, ignoring 'noauto', 'nofail', and 'x-systemd.automount' options.",
                   where);

src/kernel-install/kernel-install.c

@@ -151,37 +151,37 @@ static int context_copy(const Context *source, Context *ret) {
                         return copy.rfd;
         }
 
-        r = strdup_or_null(source->layout_other, &copy.layout_other);
+        r = strdup_to(&copy.layout_other, source->layout_other);
         if (r < 0)
                 return r;
-        r = strdup_or_null(source->conf_root, &copy.conf_root);
+        r = strdup_to(&copy.conf_root, source->conf_root);
         if (r < 0)
                 return r;
-        r = strdup_or_null(source->boot_root, &copy.boot_root);
+        r = strdup_to(&copy.boot_root, source->boot_root);
         if (r < 0)
                 return r;
-        r = strdup_or_null(source->entry_token, &copy.entry_token);
+        r = strdup_to(&copy.entry_token, source->entry_token);
         if (r < 0)
                 return r;
-        r = strdup_or_null(source->entry_dir, &copy.entry_dir);
+        r = strdup_to(&copy.entry_dir, source->entry_dir);
         if (r < 0)
                 return r;
-        r = strdup_or_null(source->version, &copy.version);
+        r = strdup_to(&copy.version, source->version);
         if (r < 0)
                 return r;
-        r = strdup_or_null(source->kernel, &copy.kernel);
+        r = strdup_to(&copy.kernel, source->kernel);
         if (r < 0)
                 return r;
         r = strv_copy_unless_empty(source->initrds, &copy.initrds);
         if (r < 0)
                 return r;
-        r = strdup_or_null(source->initrd_generator, &copy.initrd_generator);
+        r = strdup_to(&copy.initrd_generator, source->initrd_generator);
         if (r < 0)
                 return r;
-        r = strdup_or_null(source->uki_generator, &copy.uki_generator);
+        r = strdup_to(&copy.uki_generator, source->uki_generator);
         if (r < 0)
                 return r;
-        r = strdup_or_null(source->staging_area, &copy.staging_area);
+        r = strdup_to(&copy.staging_area, source->staging_area);
         if (r < 0)
                 return r;
         r = strv_copy_unless_empty(source->plugins, &copy.plugins);

src/network/networkd-address.c

@@ -613,12 +613,12 @@ int address_dup(const Address *src, Address **ret) {
         dest->nft_set_context.n_sets = 0;
 
         if (src->family == AF_INET) {
-                r = strdup_or_null(src->label, &dest->label);
+                r = strdup_to(&dest->label, src->label);
                 if (r < 0)
                         return r;
         }
 
-        r = strdup_or_null(src->netlabel, &dest->netlabel);
+        r = strdup_to(&dest->netlabel, src->netlabel);
         if (r < 0)
                 return r;
 

src/network/networkd-route-metric.c

@@ -39,7 +39,7 @@ int route_metric_copy(const RouteMetric *src, RouteMetric *dest) {
         } else
                 dest->metrics_set = NULL;
 
-        return strdup_or_null(src->tcp_congestion_control_algo, &dest->tcp_congestion_control_algo);
+        return strdup_to(&dest->tcp_congestion_control_algo, src->tcp_congestion_control_algo);
 }
 
 void route_metric_hash_func(const RouteMetric *metric, struct siphash *state) {

src/network/networkd-route-nexthop.c

@@ -218,7 +218,7 @@ static int route_nexthop_copy(const RouteNextHop *src, RouteNextHop *dest) {
         /* unset pointer copied in the above. */
         dest->ifname = NULL;
 
-        return strdup_or_null(src->ifindex > 0 ? NULL : src->ifname, &dest->ifname);
+        return strdup_to(&dest->ifname, src->ifindex > 0 ? NULL : src->ifname);
 }
 
 static int route_nexthop_dup(const RouteNextHop *src, RouteNextHop **ret) {