tree-wide: check for NULLs in more places

Fixes issues pointed out by the `cpp/inconsistent-null-check` LGTM
query.

src/core/automount.c

@@ -69,6 +69,7 @@ static int automount_send_ready(Automount *a, Set *tokens, int status);
 static void automount_init(Unit *u) {
         Automount *a = AUTOMOUNT(u);
 
+        assert(a);
         assert(u);
         assert(u->load_state == UNIT_STUB);
 

src/core/device.c

@@ -248,6 +248,7 @@ static int device_serialize(Unit *u, FILE *f, FDSet *fds) {
         _cleanup_free_ char *s = NULL;
         Device *d = DEVICE(u);
 
+        assert(d);
         assert(u);
         assert(f);
         assert(fds);
@@ -264,6 +265,7 @@ static int device_deserialize_item(Unit *u, const char *key, const char *value,
         Device *d = DEVICE(u);
         int r;
 
+        assert(d);
         assert(u);
         assert(key);
         assert(value);

src/core/mount.c

@@ -179,6 +179,7 @@ static bool mount_needs_quota(const MountParameters *p) {
 static void mount_init(Unit *u) {
         Mount *m = MOUNT(u);
 
+        assert(m);
         assert(u);
         assert(u->load_state == UNIT_STUB);
 
@@ -681,6 +682,7 @@ static int mount_load(Unit *u) {
         Mount *m = MOUNT(u);
         int r, q = 0;
 
+        assert(m);
         assert(u);
         assert(u->load_state == UNIT_STUB);
 
@@ -1256,6 +1258,7 @@ static int mount_deserialize_item(Unit *u, const char *key, const char *value, F
         Mount *m = MOUNT(u);
         int r;
 
+        assert(m);
         assert(u);
         assert(key);
         assert(value);
@@ -1794,6 +1797,9 @@ static int mount_get_timeout(Unit *u, usec_t *timeout) {
         usec_t t;
         int r;
 
+        assert(m);
+        assert(u);
+
         if (!m->timer_event_source)
                 return 0;
 

src/core/swap.c

@@ -1220,6 +1220,8 @@ static int swap_process_proc_swaps(Manager *m) {
                 LIST_FOREACH(units_by_type, u, m->units_by_type[UNIT_SWAP]) {
                         Swap *swap = SWAP(u);
 
+                        assert(swap);
+
                         swap->is_active = swap->just_activated = false;
                 }
 
@@ -1231,6 +1233,8 @@ static int swap_process_proc_swaps(Manager *m) {
         LIST_FOREACH(units_by_type, u, m->units_by_type[UNIT_SWAP]) {
                 Swap *swap = SWAP(u);
 
+                assert(swap);
+
                 if (!swap->is_active) {
 
                         swap_unset_proc_swaps(swap);
@@ -1495,6 +1499,9 @@ static int swap_get_timeout(Unit *u, usec_t *timeout) {
         usec_t t;
         int r;
 
+        assert(s);
+        assert(u);
+
         if (!s->timer_event_source)
                 return 0;
 

src/network/netdev/macsec.c

@@ -511,6 +511,8 @@ static int netdev_macsec_fill_message_create(NetDev *netdev, Link *link, sd_netl
 
         v = MACSEC(netdev);
 
+        assert(v);
+
         if (v->port > 0) {
                 r = sd_netlink_message_append_u16(m, IFLA_MACSEC_PORT, v->port);
                 if (r < 0)

src/network/networkd-network.c

@@ -214,6 +214,8 @@ int network_verify(Network *network) {
                                 else
                                         continue;
 
+                                assert(m);
+
                                 if (m->mode == NETDEV_MACVLAN_MODE_PASSTHRU)
                                         network->link_local = ADDRESS_FAMILY_NO;
 

src/resolve/resolved-dns-scope.c

@@ -1452,6 +1452,8 @@ int dns_scope_announce(DnsScope *scope, bool goodbye) {
 
                 rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR,
                                                   "_services._dns-sd._udp.local");
+                if (!rr)
+                        return log_oom();
                 rr->ptr.name = strdup(service_type);
                 rr->ttl = MDNS_DEFAULT_TTL;