Merge pull request #4391 from keszybz/treewide-macros

Use mfree more and add another function to simplify a common set&free pattern

coccinelle/free_and_replace.cocci

@@ -0,0 +1,15 @@
+@@
+expression p, q;
+@@
+- free(p);
+- p = q;
+- q = NULL;
+- return 0;
++ return free_and_replace(p, q);
+@@
+expression p, q;
+@@
+- free(p);
+- p = q;
+- q = NULL;
++ free_and_replace(p, q);

coccinelle/mfree_return.cocci

@@ -0,0 +1,6 @@
+@@
+expression p;
+@@
+- free(p);
+- return NULL;
++ return mfree(p);

src/basic/alloc-util.h

@@ -43,6 +43,14 @@ static inline void *mfree(void *memory) {
         return NULL;
 }
 
+#define free_and_replace(a, b)                  \
+        ({                                      \
+                free(a);                        \
+                (a) = (b);                      \
+                (b) = NULL;                     \
+                0;                              \
+        })
+
 void* memdup(const void *p, size_t l) _alloc_(2);
 
 static inline void freep(void *p) {

src/basic/bitmap.c

@@ -58,10 +58,8 @@ Bitmap *bitmap_copy(Bitmap *b) {
                 return NULL;
 
         ret->bitmaps = newdup(uint64_t, b->bitmaps, b->n_bitmaps);
-        if (!ret->bitmaps) {
-                free(ret);
-                return NULL;
-        }
+        if (!ret->bitmaps)
+                return mfree(ret);
 
         ret->n_bitmaps = ret->bitmaps_allocated = b->n_bitmaps;
         return ret;

src/basic/env-util.c

@@ -544,8 +544,7 @@ char *replace_env(const char *format, char **env) {
         return k;
 
 fail:
-        free(r);
-        return NULL;
+        return mfree(r);
 }
 
 char **replace_env_argv(char **argv, char **env) {

src/basic/fs-util.c

@@ -678,9 +678,7 @@ int chase_symlinks(const char *path, const char *_root, char **ret) {
                             !path_startswith(parent, root))
                                 return -EINVAL;
 
-                        free(done);
-                        done = parent;
-                        parent = NULL;
+                        free_and_replace(done, parent);
 
                         fd_parent = openat(fd, "..", O_CLOEXEC|O_NOFOLLOW|O_PATH);
                         if (fd_parent < 0)
@@ -724,9 +722,7 @@ int chase_symlinks(const char *path, const char *_root, char **ret) {
                                 if (fd < 0)
                                         return -errno;
 
-                                free(buffer);
-                                buffer = destination;
-                                destination = NULL;
+                                free_and_replace(buffer, destination);
 
                                 todo = buffer;
                                 free(done);

src/basic/path-util.c

@@ -288,9 +288,7 @@ char **path_strv_resolve(char **l, const char *prefix) {
                         } else {
                                 /* canonicalized path goes outside of
                                  * prefix, keep the original path instead */
-                                free(u);
-                                u = orig;
-                                orig = NULL;
+                                free_and_replace(u, orig);
                         }
                 } else
                         free(t);

src/basic/prioq.c

@@ -62,9 +62,7 @@ Prioq* prioq_free(Prioq *q) {
                 return NULL;
 
         free(q->items);
-        free(q);
-
-        return NULL;
+        return mfree(q);
 }
 
 int prioq_ensure_allocated(Prioq **q, compare_func_t compare_func) {

src/basic/replace-var.c

@@ -107,6 +107,5 @@ char *replace_var(const char *text, char *(*lookup)(const char *variable, void*u
         return r;
 
 oom:
-        free(r);
-        return NULL;
+        return mfree(r);
 }

src/basic/strbuf.c

@@ -62,8 +62,7 @@ struct strbuf *strbuf_new(void) {
 err:
         free(str->buf);
         free(str->root);
-        free(str);
-        return NULL;
+        return mfree(str);
 }
 
 static void strbuf_node_cleanup(struct strbuf_node *node) {

src/basic/string-util.c

@@ -610,8 +610,7 @@ char *strreplace(const char *text, const char *old_string, const char *new_strin
         return r;
 
 oom:
-        free(r);
-        return NULL;
+        return mfree(r);
 }
 
 char *strip_tab_ansi(char **ibuf, size_t *_isz) {
@@ -682,8 +681,7 @@ char *strip_tab_ansi(char **ibuf, size_t *_isz) {
 
         if (ferror(f)) {
                 fclose(f);
-                free(obuf);
-                return NULL;
+                return mfree(obuf);
         }
 
         fclose(f);

src/basic/strv.c

@@ -87,8 +87,7 @@ void strv_clear(char **l) {
 
 char **strv_free(char **l) {
         strv_clear(l);
-        free(l);
-        return NULL;
+        return mfree(l);
 }
 
 char **strv_free_erase(char **l) {
@@ -426,8 +425,7 @@ char *strv_join_quoted(char **l) {
         return buf;
 
  oom:
-        free(buf);
-        return NULL;
+        return mfree(buf);
 }
 
 int strv_push(char ***l, char *value) {
@@ -869,8 +867,7 @@ char ***strv_free_free(char ***l) {
         for (i = l; *i; i++)
                 strv_free(*i);
 
-        free(l);
-        return NULL;
+        return mfree(l);
 }
 
 char **strv_skip(char **l, size_t n) {

src/core/dynamic-user.c

@@ -42,9 +42,7 @@ static DynamicUser* dynamic_user_free(DynamicUser *d) {
                 (void) hashmap_remove(d->manager->dynamic_users, d->name);
 
         safe_close_pair(d->storage_socket);
-        free(d);
-
-        return NULL;
+        return mfree(d);
 }
 
 static int dynamic_user_add(Manager *m, const char *name, int storage_socket[2], DynamicUser **ret) {

src/core/execute.c

@@ -3740,9 +3740,7 @@ ExecRuntime *exec_runtime_unref(ExecRuntime *r) {
         free(r->tmp_dir);
         free(r->var_tmp_dir);
         safe_close_pair(r->netns_storage_socket);
-        free(r);
-
-        return NULL;
+        return mfree(r);
 }
 
 int exec_runtime_serialize(Unit *u, ExecRuntime *rt, FILE *f, FDSet *fds) {

src/core/load-fragment.c

@@ -1591,11 +1591,7 @@ int config_parse_fdname(
                 return 0;
         }
 
-        free(s->fdname);
-        s->fdname = p;
-        p = NULL;
-
-        return 0;
+        return free_and_replace(s->fdname, p);
 }
 
 int config_parse_service_sockets(
@@ -2052,9 +2048,7 @@ int config_parse_working_directory(
                         return 0;
                 }
 
-                free(c->working_directory);
-                c->working_directory = k;
-                k = NULL;
+                free_and_replace(c->working_directory, k);
 
                 c->working_directory_home = false;
         }

src/core/manager.c

@@ -1119,8 +1119,7 @@ Manager* manager_free(Manager *m) {
         hashmap_free(m->uid_refs);
         hashmap_free(m->gid_refs);
 
-        free(m);
-        return NULL;
+        return mfree(m);
 }
 
 void manager_enumerate(Manager *m) {

src/core/mount.c

@@ -1484,17 +1484,9 @@ static int mount_setup_unit(
 
         MOUNT(u)->from_proc_self_mountinfo = true;
 
-        free(p->what);
-        p->what = w;
-        w = NULL;
-
-        free(p->options);
-        p->options = o;
-        o = NULL;
-
-        free(p->fstype);
-        p->fstype = f;
-        f = NULL;
+        free_and_replace(p->what, w);
+        free_and_replace(p->options, o);
+        free_and_replace(p->fstype, f);
 
         if (load_extras) {
                 r = mount_add_extras(MOUNT(u));

src/core/service.c

@@ -3088,9 +3088,7 @@ static void service_notify_message(Unit *u, pid_t pid, char **tags, FDSet *fds)
 
                 if (!streq_ptr(s->status_text, t)) {
 
-                        free(s->status_text);
-                        s->status_text = t;
-                        t = NULL;
+                        free_and_replace(s->status_text, t);
 
                         notify_dbus = true;
                 }

src/core/transaction.c

@@ -1085,10 +1085,8 @@ Transaction *transaction_new(bool irreversible) {
                 return NULL;
 
         tr->jobs = hashmap_new(NULL);
-        if (!tr->jobs) {
-                free(tr);
-                return NULL;
-        }
+        if (!tr->jobs)
+                return mfree(tr);
 
         tr->irreversible = irreversible;
 

src/core/unit.c

@@ -88,10 +88,8 @@ Unit *unit_new(Manager *m, size_t size) {
                 return NULL;
 
         u->names = set_new(&string_hash_ops);
-        if (!u->names) {
-                free(u);
-                return NULL;
-        }
+        if (!u->names)
+                return mfree(u);
 
         u->manager = m;
         u->type = _UNIT_TYPE_INVALID;

src/cryptsetup/cryptsetup-generator.c

@@ -264,16 +264,13 @@ static crypto_device *get_crypto_device(const char *uuid) {
                 d->keyfile = d->options = d->name = NULL;
 
                 d->uuid = strdup(uuid);
-                if (!d->uuid) {
-                        free(d);
-                        return NULL;
-                }
+                if (!d->uuid)
+                        return mfree(d);
 
                 r = hashmap_put(arg_disks, d->uuid, d);
                 if (r < 0) {
                         free(d->uuid);
-                        free(d);
-                        return NULL;
+                        return mfree(d);
                 }
         }
 

src/import/curl-util.c

@@ -235,9 +235,7 @@ CurlGlue *curl_glue_unref(CurlGlue *g) {
 
         sd_event_source_unref(g->timer);
         sd_event_unref(g->event);
-        free(g);
-
-        return NULL;
+        return mfree(g);
 }
 
 int curl_glue_new(CurlGlue **glue, sd_event *event) {

src/import/export-raw.c

@@ -87,9 +87,7 @@ RawExport *raw_export_unref(RawExport *e) {
 
         free(e->buffer);
         free(e->path);
-        free(e);
-
-        return NULL;
+        return mfree(e);
 }
 
 int raw_export_new(

src/import/export-tar.c

@@ -91,9 +91,7 @@ TarExport *tar_export_unref(TarExport *e) {
 
         free(e->buffer);
         free(e->path);
-        free(e);
-
-        return NULL;
+        return mfree(e);
 }
 
 int tar_export_new(

src/import/import-raw.c

@@ -100,9 +100,7 @@ RawImport* raw_import_unref(RawImport *i) {
         free(i->final_path);
         free(i->image_root);
         free(i->local);
-        free(i);
-
-        return NULL;
+        return mfree(i);
 }
 
 int raw_import_new(

src/import/import-tar.c

@@ -107,9 +107,7 @@ TarImport* tar_import_unref(TarImport *i) {
         free(i->final_path);
         free(i->image_root);
         free(i->local);
-        free(i);
-
-        return NULL;
+        return mfree(i);
 }
 
 int tar_import_new(

src/import/importd.c

@@ -141,8 +141,7 @@ static Transfer *transfer_unref(Transfer *t) {
         safe_close(t->stdin_fd);
         safe_close(t->stdout_fd);
 
-        free(t);
-        return NULL;
+        return mfree(t);
 }
 
 DEFINE_TRIVIAL_CLEANUP_FUNC(Transfer*, transfer_unref);
@@ -548,8 +547,7 @@ static Manager *manager_unref(Manager *m) {
         m->bus = sd_bus_flush_close_unref(m->bus);
         sd_event_unref(m->event);
 
-        free(m);
-        return NULL;
+        return mfree(m);
 }
 
 DEFINE_TRIVIAL_CLEANUP_FUNC(Manager*, manager_unref);

src/import/pull-job.c

@@ -50,9 +50,7 @@ PullJob* pull_job_unref(PullJob *j) {
         free(j->payload);
         free(j->checksum);
 
-        free(j);
-
-        return NULL;
+        return mfree(j);
 }
 
 static void pull_job_finish(PullJob *j, int ret) {

src/import/pull-raw.c

@@ -110,9 +110,7 @@ RawPull* raw_pull_unref(RawPull *i) {
         free(i->settings_path);
         free(i->image_root);
         free(i->local);
-        free(i);
-
-        return NULL;
+        return mfree(i);
 }
 
 int raw_pull_new(

src/import/pull-tar.c

@@ -114,9 +114,7 @@ TarPull* tar_pull_unref(TarPull *i) {
         free(i->settings_path);
         free(i->image_root);
         free(i->local);
-        free(i);
-
-        return NULL;
+        return mfree(i);
 }
 
 int tar_pull_new(

src/journal-remote/journal-remote-write.c

@@ -75,10 +75,8 @@ Writer* writer_new(RemoteServer *server) {
         memset(&w->metrics, 0xFF, sizeof(w->metrics));
 
         w->mmap = mmap_cache_new();
-        if (!w->mmap) {
-                free(w);
-                return NULL;
-        }
+        if (!w->mmap)
+                return mfree(w);
 
         w->n_ref = 1;
         w->server = server;
@@ -103,9 +101,7 @@ Writer* writer_free(Writer *w) {
         if (w->mmap)
                 mmap_cache_unref(w->mmap);
 
-        free(w);
-
-        return NULL;
+        return mfree(w);
 }
 
 Writer* writer_unref(Writer *w) {

src/journal-remote/journal-upload.c

@@ -527,9 +527,7 @@ static int perform_upload(Uploader *u) {
                 log_debug("Upload finished successfully with code %ld: %s",
                           status, strna(u->answer));
 
-        free(u->last_cursor);
-        u->last_cursor = u->current_cursor;
-        u->current_cursor = NULL;
+        free_and_replace(u->last_cursor, u->current_cursor);
 
         return update_cursor_state(u);
 }

src/journal/journal-file.c

@@ -394,8 +394,7 @@ JournalFile* journal_file_close(JournalFile *f) {
                 gcry_md_close(f->hmac);
 #endif
 
-        free(f);
-        return NULL;
+        return mfree(f);
 }
 
 void journal_file_close_set(Set *s) {

src/journal/mmap-cache.c

@@ -325,10 +325,8 @@ static FileDescriptor* fd_add(MMapCache *m, int fd) {
         f->fd = fd;
 
         r = hashmap_put(m->fds, FD_TO_PTR(fd), f);
-        if (r < 0) {
-                free(f);
-                return NULL;
-        }
+        if (r < 0)
+                return mfree(f);
 
         return f;
 }

src/journal/sd-journal.c

@@ -387,7 +387,7 @@ _public_ int sd_journal_add_disjunction(sd_journal *j) {
 }
 
 static char *match_make_string(Match *m) {
-        char *p, *r;
+        char *p = NULL, *r;
         Match *i;
         bool enclose = false;
 
@@ -397,15 +397,12 @@ static char *match_make_string(Match *m) {
         if (m->type == MATCH_DISCRETE)
                 return strndup(m->data, m->size);
 
-        p = NULL;
         LIST_FOREACH(matches, i, m->matches) {
                 char *t, *k;
 
                 t = match_make_string(i);
-                if (!t) {
-                        free(p);
-                        return NULL;
-                }
+                if (!t)
+                        return mfree(p);
 
                 if (p) {
                         k = strjoin(p, m->type == MATCH_OR_TERM ? " OR " : " AND ", t, NULL);

src/libsystemd-network/ndisc-router.c

@@ -49,8 +49,7 @@ _public_ sd_ndisc_router* sd_ndisc_router_unref(sd_ndisc_router *rt) {
         if (rt->n_ref > 0)
                 return NULL;
 
-        free(rt);
-        return NULL;
+        return mfree(rt);
 }
 
 sd_ndisc_router *ndisc_router_new(size_t raw_size) {

src/libsystemd-network/sd-dhcp-client.c

@@ -1873,9 +1873,7 @@ sd_dhcp_client *sd_dhcp_client_unref(sd_dhcp_client *client) {
         free(client->req_opts);
         free(client->hostname);
         free(client->vendor_class_identifier);
-        free(client);
-
-        return NULL;
+        return mfree(client);
 }
 
 int sd_dhcp_client_new(sd_dhcp_client **ret) {

src/libsystemd-network/sd-dhcp-lease.c

@@ -282,9 +282,7 @@ sd_dhcp_lease *sd_dhcp_lease_unref(sd_dhcp_lease *lease) {
         free(lease->static_route);
         free(lease->client_id);
         free(lease->vendor_specific);
-        free(lease);
-
-        return NULL;
+        return mfree(lease);
 }
 
 static int lease_parse_u32(const uint8_t *option, size_t len, uint32_t *ret, uint32_t min) {

src/libsystemd-network/sd-dhcp-server.c

@@ -178,9 +178,7 @@ sd_dhcp_server *sd_dhcp_server_unref(sd_dhcp_server *server) {
         hashmap_free(server->leases_by_client_id);
 
         free(server->bound_leases);
-        free(server);
-
-        return NULL;
+        return mfree(server);
 }
 
 int sd_dhcp_server_new(sd_dhcp_server **ret, int ifindex) {

src/libsystemd-network/sd-dhcp6-client.c

@@ -1300,9 +1300,7 @@ sd_dhcp6_client *sd_dhcp6_client_unref(sd_dhcp6_client *client) {
         sd_dhcp6_client_detach_event(client);
 
         free(client->req_opts);
-        free(client);
-
-        return NULL;
+        return mfree(client);
 }
 
 int sd_dhcp6_client_new(sd_dhcp6_client **ret) {

src/libsystemd-network/sd-dhcp6-lease.c

@@ -389,9 +389,7 @@ sd_dhcp6_lease *sd_dhcp6_lease_unref(sd_dhcp6_lease *lease) {
         free(lease->ntp);
 
         lease->ntp_fqdn = strv_free(lease->ntp_fqdn);
-        free(lease);
-
-        return NULL;
+        return mfree(lease);
 }
 
 int dhcp6_lease_new(sd_dhcp6_lease **ret) {

src/libsystemd-network/sd-ipv4acd.c

@@ -135,9 +135,7 @@ sd_ipv4acd *sd_ipv4acd_unref(sd_ipv4acd *acd) {
         ipv4acd_reset(acd);
         sd_ipv4acd_detach_event(acd);
 
-        free(acd);
-
-        return NULL;
+        return mfree(acd);
 }
 
 int sd_ipv4acd_new(sd_ipv4acd **ret) {

src/libsystemd-network/sd-ipv4ll.c

@@ -90,9 +90,7 @@ sd_ipv4ll *sd_ipv4ll_unref(sd_ipv4ll *ll) {
                 return NULL;
 
         sd_ipv4acd_unref(ll->acd);
-        free(ll);
-
-        return NULL;
+        return mfree(ll);
 }
 
 int sd_ipv4ll_new(sd_ipv4ll **ret) {

src/libsystemd-network/sd-lldp.c

@@ -374,9 +374,7 @@ _public_ sd_lldp* sd_lldp_unref(sd_lldp *lldp) {
 
         hashmap_free(lldp->neighbor_by_id);
         prioq_free(lldp->neighbor_by_expiry);
-        free(lldp);
-
-        return NULL;
+        return mfree(lldp);
 }
 
 _public_ int sd_lldp_new(sd_lldp **ret) {

src/libsystemd-network/sd-ndisc.c

@@ -148,9 +148,7 @@ _public_ sd_ndisc *sd_ndisc_unref(sd_ndisc *nd) {
 
         ndisc_reset(nd);
         sd_ndisc_detach_event(nd);
-        free(nd);
-
-        return NULL;
+        return mfree(nd);
 }
 
 _public_ int sd_ndisc_new(sd_ndisc **ret) {

src/libsystemd/sd-bus/bus-slot.c

@@ -212,9 +212,7 @@ _public_ sd_bus_slot* sd_bus_slot_unref(sd_bus_slot *slot) {
 
         bus_slot_disconnect(slot);
         free(slot->description);
-        free(slot);
-
-        return NULL;
+        return mfree(slot);
 }
 
 _public_ sd_bus* sd_bus_slot_get_bus(sd_bus_slot *slot) {

src/libsystemd/sd-bus/bus-track.c

@@ -74,9 +74,7 @@ static struct track_item* track_item_free(struct track_item *i) {
 
         sd_bus_slot_unref(i->slot);
         free(i->name);
-        free(i);
-
-        return NULL;
+        return mfree(i);
 }
 
 DEFINE_TRIVIAL_CLEANUP_FUNC(struct track_item*, track_item_free);
@@ -206,9 +204,7 @@ _public_ sd_bus_track* sd_bus_track_unref(sd_bus_track *track) {
         bus_track_remove_from_queue(track);
         hashmap_free(track->names);
         sd_bus_unref(track->bus);
-        free(track);
-
-        return NULL;
+        return mfree(track);
 }
 
 static int on_name_owner_changed(sd_bus_message *message, void *userdata, sd_bus_error *error) {

src/libudev/libudev-list.c

@@ -166,17 +166,16 @@ struct udev_list_entry *udev_list_entry_add(struct udev_list *list, const char *
         entry = new0(struct udev_list_entry, 1);
         if (entry == NULL)
                 return NULL;
+
         entry->name = strdup(name);
-        if (entry->name == NULL) {
-                free(entry);
-                return NULL;
-        }
+        if (entry->name == NULL)
+                return mfree(entry);
+
         if (value != NULL) {
                 entry->value = strdup(value);
                 if (entry->value == NULL) {
                         free(entry->name);
-                        free(entry);
-                        return NULL;
+                        return mfree(entry);
                 }
         }
 
@@ -193,8 +192,7 @@ struct udev_list_entry *udev_list_entry_add(struct udev_list *list, const char *
                         if (entries == NULL) {
                                 free(entry->name);
                                 free(entry->value);
-                                free(entry);
-                                return NULL;
+                                return mfree(entry);
                         }
                         list->entries = entries;
                         list->entries_max += add;

src/libudev/libudev-monitor.c

@@ -207,8 +207,7 @@ struct udev_monitor *udev_monitor_new_from_netlink_fd(struct udev *udev, const c
                 udev_monitor->sock = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_KOBJECT_UEVENT);
                 if (udev_monitor->sock < 0) {
                         log_debug_errno(errno, "error getting socket: %m");
-                        free(udev_monitor);
-                        return NULL;
+                        return mfree(udev_monitor);
                 }
         } else {
                 udev_monitor->bound = true;

src/login/logind-button.c

@@ -43,15 +43,12 @@ Button* button_new(Manager *m, const char *name) {
                 return NULL;
 
         b->name = strdup(name);
-        if (!b->name) {
-                free(b);
-                return NULL;
-        }
+        if (!b->name)
+                return mfree(b);
 
         if (hashmap_put(m->buttons, b->name, b) < 0) {
                 free(b->name);
-                free(b);
-                return NULL;
+                return mfree(b);
         }
 
         b->manager = m;

src/login/logind-device.c

@@ -34,15 +34,12 @@ Device* device_new(Manager *m, const char *sysfs, bool master) {
                 return NULL;
 
         d->sysfs = strdup(sysfs);
-        if (!d->sysfs) {
-                free(d);
-                return NULL;
-        }
+        if (!d->sysfs)
+                return mfree(d);
 
         if (hashmap_put(m->devices, d->sysfs, d) < 0) {
                 free(d->sysfs);
-                free(d);
-                return NULL;
+                return mfree(d);
         }
 
         d->manager = m;

src/login/logind-inhibit.c

@@ -45,17 +45,14 @@ Inhibitor* inhibitor_new(Manager *m, const char* id) {
                 return NULL;
 
         i->state_file = strappend("/run/systemd/inhibit/", id);
-        if (!i->state_file) {
-                free(i);
-                return NULL;
-        }
+        if (!i->state_file)
+                return mfree(i);
 
         i->id = basename(i->state_file);
 
         if (hashmap_put(m->inhibitors, i->id, i) < 0) {
                 free(i->state_file);
-                free(i);
-                return NULL;
+                return mfree(i);
         }
 
         i->manager = m;

src/login/logind-seat.c

@@ -48,18 +48,15 @@ Seat *seat_new(Manager *m, const char *id) {
                 return NULL;
 
         s->state_file = strappend("/run/systemd/seats/", id);
-        if (!s->state_file) {
-                free(s);
-                return NULL;
-        }
+        if (!s->state_file)
+                return mfree(s);
 
         s->id = basename(s->state_file);
         s->manager = m;
 
         if (hashmap_put(m->seats, s->id, s) < 0) {
                 free(s->state_file);
-                free(s);
-                return NULL;
+                return mfree(s);
         }
 
         return s;

src/login/logind-session.c

@@ -62,16 +62,13 @@ Session* session_new(Manager *m, const char *id) {
                 return NULL;
 
         s->state_file = strappend("/run/systemd/sessions/", id);
-        if (!s->state_file) {
-                free(s);
-                return NULL;
-        }
+        if (!s->state_file)
+                return mfree(s);
 
         s->devices = hashmap_new(&devt_hash_ops);
         if (!s->devices) {
                 free(s->state_file);
-                free(s);
-                return NULL;
+                return mfree(s);
         }
 
         s->id = basename(s->state_file);
@@ -79,8 +76,7 @@ Session* session_new(Manager *m, const char *id) {
         if (hashmap_put(m->sessions, s->id, s) < 0) {
                 hashmap_free(s->devices);
                 free(s->state_file);
-                free(s);
-                return NULL;
+                return mfree(s);
         }
 
         s->manager = m;

src/machine/machine.c

@@ -80,9 +80,7 @@ Machine* machine_new(Manager *manager, MachineClass class, const char *name) {
 fail:
         free(m->state_file);
         free(m->name);
-        free(m);
-
-        return NULL;
+        return mfree(m);
 }
 
 void machine_free(Machine *m) {

src/machine/operation.c

@@ -147,6 +147,5 @@ Operation *operation_free(Operation *o) {
         if (o->machine)
                 LIST_REMOVE(operations_by_machine, o->machine->operations, o);
 
-        free(o);
-        return NULL;
+        return mfree(o);
 }

src/network/networkd-wait-online-link.c

@@ -77,8 +77,7 @@ Link *link_free(Link *l) {
         }
 
         free(l->ifname);
-        free(l);
-        return NULL;
+        return mfree(l);
  }
 
 int link_update_rtnl(Link *l, sd_netlink_message *m) {

src/nspawn/nspawn-settings.c

@@ -101,9 +101,7 @@ Settings* settings_free(Settings *s) {
         expose_port_free_all(s->expose_ports);
 
         custom_mount_free_all(s->custom_mounts, s->n_custom_mounts);
-        free(s);
-
-        return NULL;
+        return mfree(s);
 }
 
 bool settings_private_network(Settings *s) {

src/resolve/resolved-dns-query.c

@@ -83,9 +83,7 @@ DnsQueryCandidate* dns_query_candidate_free(DnsQueryCandidate *c) {
         if (c->scope)
                 LIST_REMOVE(candidates_by_scope, c->scope->query_candidates, c);
 
-        free(c);
-
-        return NULL;
+        return mfree(c);
 }
 
 static int dns_query_candidate_next_search_domain(DnsQueryCandidate *c) {
@@ -421,9 +419,7 @@ DnsQuery *dns_query_free(DnsQuery *q) {
                 q->manager->n_dns_queries--;
         }
 
-        free(q);
-
-        return NULL;
+        return mfree(q);
 }
 
 int dns_query_new(

src/resolve/resolved-dns-rr.c

@@ -73,10 +73,8 @@ DnsResourceKey* dns_resource_key_new_redirect(const DnsResourceKey *key, const D
                         return dns_resource_key_ref((DnsResourceKey*) key);
 
                 k = dns_resource_key_new_consume(key->class, key->type, destination);
-                if (!k) {
-                        free(destination);
-                        return NULL;
-                }
+                if (!k)
+                        return mfree(destination);
 
                 return k;
         }
@@ -513,9 +511,7 @@ DnsResourceRecord* dns_resource_record_unref(DnsResourceRecord *rr) {
         }
 
         free(rr->to_string);
-        free(rr);
-
-        return NULL;
+        return mfree(rr);
 }
 
 int dns_resource_record_new_reverse(DnsResourceRecord **ret, int family, const union in_addr_union *address, const char *hostname) {

src/resolve/resolved-dns-scope.c

@@ -128,9 +128,7 @@ DnsScope* dns_scope_free(DnsScope *s) {
         dns_zone_flush(&s->zone);
 
         LIST_REMOVE(scopes, s->manager->dns_scopes, s);
-        free(s);
-
-        return NULL;
+        return mfree(s);
 }
 
 DnsServer *dns_scope_get_dns_server(DnsScope *s) {

src/resolve/resolved-dns-search-domain.c

@@ -104,9 +104,7 @@ DnsSearchDomain* dns_search_domain_unref(DnsSearchDomain *d) {
                 return NULL;
 
         free(d->name);
-        free(d);
-
-        return NULL;
+        return mfree(d);
 }
 
 void dns_search_domain_unlink(DnsSearchDomain *d) {

src/resolve/resolved-dns-server.c

@@ -139,8 +139,7 @@ DnsServer* dns_server_unref(DnsServer *s)  {
                 return NULL;
 
         free(s->server_string);
-        free(s);
-        return NULL;
+        return mfree(s);
 }
 
 void dns_server_unlink(DnsServer *s) {

src/resolve/resolved-dns-stream.c

@@ -343,9 +343,7 @@ DnsStream *dns_stream_unref(DnsStream *s) {
         dns_packet_unref(s->write_packet);
         dns_packet_unref(s->read_packet);
 
-        free(s);
-
-        return NULL;
+        return mfree(s);
 }
 
 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsStream*, dns_stream_unref);

src/resolve/resolved-dns-transaction.c

@@ -134,8 +134,7 @@ DnsTransaction* dns_transaction_free(DnsTransaction *t) {
         dns_answer_unref(t->validated_keys);
         dns_resource_key_unref(t->key);
 
-        free(t);
-        return NULL;
+        return mfree(t);
 }
 
 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction*, dns_transaction_free);

src/resolve/resolved-link.c

@@ -101,8 +101,7 @@ Link *link_free(Link *l) {
 
         free(l->state_file);
 
-        free(l);
-        return NULL;
+        return mfree(l);
 }
 
 void link_allocate_scopes(Link *l) {
@@ -698,8 +697,7 @@ LinkAddress *link_address_free(LinkAddress *a) {
         dns_resource_record_unref(a->llmnr_address_rr);
         dns_resource_record_unref(a->llmnr_ptr_rr);
 
-        free(a);
-        return NULL;
+        return mfree(a);
 }
 
 void link_address_add_rrs(LinkAddress *a, bool force_remove) {

src/resolve/resolved-manager.c

@@ -630,9 +630,7 @@ Manager *manager_free(Manager *m) {
         dns_trust_anchor_flush(&m->trust_anchor);
         manager_etc_hosts_flush(m);
 
-        free(m);
-
-        return NULL;
+        return mfree(m);
 }
 
 int manager_recv(Manager *m, int fd, DnsProtocol protocol, DnsPacket **ret) {

src/shared/install.c

@@ -214,8 +214,8 @@ static int path_is_config(const LookupPaths *p, const char *path) {
         assert(p);
         assert(path);
 
-        /* Note that we do *not* have generic checks for /etc or /run in place, since with them we couldn't discern
-         * configuration from transient or generated units */
+        /* Note that we do *not* have generic checks for /etc or /run in place, since with
+         * them we couldn't discern configuration from transient or generated units */
 
         parent = dirname_malloc(path);
         if (!parent)
@@ -232,8 +232,8 @@ static int path_is_runtime(const LookupPaths *p, const char *path) {
         assert(p);
         assert(path);
 
-        /* Everything in /run is considered runtime. On top of that we also add explicit checks for the various runtime
-         * directories, as safety net. */
+        /* Everything in /run is considered runtime. On top of that we also add
+         * explicit checks for the various runtime directories, as safety net. */
 
         rpath = skip_root(p, path);
         if (rpath && path_startswith(rpath, "/run"))
@@ -1084,7 +1084,7 @@ static int config_parse_default_instance(
 
         UnitFileInstallInfo *i = data;
         const char *name;
-        char *printed;
+        _cleanup_free_ char *printed = NULL;
         int r;
 
         assert(filename);
@@ -1104,15 +1104,10 @@ static int config_parse_default_instance(
         if (r < 0)
                 return r;
 
-        if (!unit_instance_is_valid(printed)) {
-                free(printed);
+        if (!unit_instance_is_valid(printed))
                 return -EINVAL;
-        }
 
-        free(i->default_instance);
-        i->default_instance = printed;
-
-        return 0;
+        return free_and_replace(i->default_instance, printed);
 }
 
 static int unit_file_load(
@@ -1358,9 +1353,7 @@ static int install_info_follow(
         if (!streq(basename(i->symlink_target), i->name))
                 return -EXDEV;
 
-        free(i->path);
-        i->path = i->symlink_target;
-        i->symlink_target = NULL;
+        free_and_replace(i->path, i->symlink_target);
         i->type = _UNIT_FILE_TYPE_INVALID;
 
         return unit_file_load_or_readlink(c, i, i->path, root_dir, flags);

src/shared/machine-image.c

@@ -62,8 +62,7 @@ Image *image_unref(Image *i) {
 
         free(i->name);
         free(i->path);
-        free(i);
-        return NULL;
+        return mfree(i);
 }
 
 static char **image_settings_path(Image *image) {

src/shared/ptyfwd.c

@@ -463,8 +463,7 @@ int pty_forward_new(
 
 PTYForward *pty_forward_free(PTYForward *f) {
         pty_forward_disconnect(f);
-        free(f);
-        return NULL;
+        return mfree(f);
 }
 
 int pty_forward_get_last_char(PTYForward *f, char *ch) {

src/timesync/timesyncd-server.c

@@ -61,8 +61,7 @@ ServerAddress* server_address_free(ServerAddress *a) {
                         manager_set_server_address(a->name->manager, NULL);
         }
 
-        free(a);
-        return NULL;
+        return mfree(a);
 }
 
 int server_name_new(
@@ -137,9 +136,7 @@ ServerName *server_name_free(ServerName *n) {
         log_debug("Removed server %s.", n->string);
 
         free(n->string);
-        free(n);
-
-        return NULL;
+        return mfree(n);
 }
 
 void server_name_flush_addresses(ServerName *n) {

src/udev/udev-ctrl.c

@@ -211,8 +211,7 @@ struct udev_ctrl_connection *udev_ctrl_get_connection(struct udev_ctrl *uctrl) {
 err:
         if (conn->sock >= 0)
                 close(conn->sock);
-        free(conn);
-        return NULL;
+        return mfree(conn);
 }
 
 struct udev_ctrl_connection *udev_ctrl_connection_ref(struct udev_ctrl_connection *conn) {

src/udev/udev-rules.c

@@ -1583,8 +1583,7 @@ struct udev_rules *udev_rules_unref(struct udev_rules *rules) {
         strbuf_cleanup(rules->strbuf);
         free(rules->uids);
         free(rules->gids);
-        free(rules);
-        return NULL;
+        return mfree(rules);
 }
 
 bool udev_rules_check_timestamp(struct udev_rules *rules) {