basic/list: drop LIST_IS_EMPTY

This was a trivial wrapper that didn't provide any added value. With more
complicated structures like strvs, hashmaps, sets, and arrays, it is possible
to have an empty container. But in case of a list, the list is empty only when
the head is missing.

Also, we generally want the positive condition, so we replace many
if (!LIST_IS_EMPTY(x)) with just if (x).

coccinelle/macros.h

@@ -189,8 +189,6 @@
              (i) != (p);                                                \
              (i) = (i)->name##_next ? (i)->name##_next : (head))
 
-#define LIST_IS_EMPTY(head)                                             \
-        (!(head))
 #define LIST_JOIN(name,a,b)                                             \
         do {                                                            \
                 assert(b);                                              \

src/basic/list.h

@@ -170,9 +170,6 @@
              i != (p);                                                  \
              i = i->name##_next ? i->name##_next : (head))
 
-#define LIST_IS_EMPTY(head)                                             \
-        (!(head))
-
 /* Join two lists tail to head: a->b, c->d to a->b->c->d and de-initialise second list */
 #define LIST_JOIN(name,a,b)                                             \
         do {                                                            \

src/core/cgroup.c

@@ -1689,7 +1689,7 @@ static bool unit_get_needs_bpf_foreign_program(Unit *u) {
         if (!c)
                 return false;
 
-        return !LIST_IS_EMPTY(c->bpf_foreign_programs);
+        return !!c->bpf_foreign_programs;
 }
 
 static bool unit_get_needs_socket_bind(Unit *u) {

src/core/dbus-cgroup.c

@@ -737,7 +737,7 @@ static int bus_cgroup_set_transient_property(
 
                         unit_write_setting(u, flags, name, buf);
 
-                        if (!LIST_IS_EMPTY(c->bpf_foreign_programs)) {
+                        if (c->bpf_foreign_programs) {
                                 r = bpf_foreign_supported();
                                 if (r < 0)
                                         return r;

src/core/dbus-execute.c

@@ -1698,16 +1698,16 @@ int bus_exec_context_set_transient_property(
                         return r;
 
                 if (!UNIT_WRITE_FLAGS_NOOP(flags)) {
-                        if (LIST_IS_EMPTY(options)) {
+                        if (options) {
-                                c->root_image_options = mount_options_free_all(c->root_image_options);
-                                unit_write_settingf(u, flags, name, "%s=", name);
-                        } else {
                                 LIST_JOIN(mount_options, c->root_image_options, options);
                                 unit_write_settingf(
                                                 u, flags|UNIT_ESCAPE_SPECIFIERS, name,
                                                 "%s=%s",
                                                 name,
                                                 format_str);
+                        } else {
+                                c->root_image_options = mount_options_free_all(c->root_image_options);
+                                unit_write_settingf(u, flags, name, "%s=", name);
                         }
                 }
 

src/core/dbus-util.c

@@ -216,7 +216,7 @@ int bus_read_mount_options(
         if (r < 0)
                 return r;
 
-        if (!LIST_IS_EMPTY(options)) {
+        if (options) {
                 if (ret_format_str) {
                         char *final = strjoin(*ret_format_str, !isempty(*ret_format_str) ? separator : "", format_str);
                         if (!final)

src/core/load-fragment.c

@@ -1691,11 +1691,11 @@ int config_parse_root_image_options(
                 LIST_APPEND(mount_options, options, TAKE_PTR(o));
         }
 
-        /* empty spaces/separators only */
+        if (options)
-        if (LIST_IS_EMPTY(options))
-                c->root_image_options = mount_options_free_all(c->root_image_options);
-        else
                 LIST_JOIN(mount_options, c->root_image_options, options);
+        else
+                /* empty spaces/separators only */
+                c->root_image_options = mount_options_free_all(c->root_image_options);
 
         return 0;
 }

src/core/unit.c

@@ -4138,7 +4138,7 @@ int unit_patch_contexts(Unit *u) {
                     cc->device_policy == CGROUP_DEVICE_POLICY_AUTO)
                         cc->device_policy = CGROUP_DEVICE_POLICY_CLOSED;
 
-                if ((ec->root_image || !LIST_IS_EMPTY(ec->mount_images)) &&
+                if ((ec->root_image || ec->mount_images) &&
                     (cc->device_policy != CGROUP_DEVICE_POLICY_AUTO || cc->device_allow)) {
 
                         /* When RootImage= or MountImages= is specified, the following devices are touched. */

src/libsystemd/sd-event/sd-event.c

@@ -1799,7 +1799,7 @@ static void event_free_inode_data(
         if (!d)
                 return;
 
-        assert(LIST_IS_EMPTY(d->event_sources));
+        assert(!d->event_sources);
 
         if (d->fd >= 0) {
                 LIST_REMOVE(to_close, e->inode_data_to_close, d);
@@ -1862,7 +1862,7 @@ static void event_gc_inode_data(
         if (!d)
                 return;
 
-        if (!LIST_IS_EMPTY(d->event_sources))
+        if (d->event_sources)
                 return;
 
         inotify_data = d->inotify_data;
@@ -3874,7 +3874,7 @@ _public_ int sd_event_prepare(sd_event *e) {
 
         event_close_inode_data_fds(e);
 
-        if (event_next_pending(e) || e->need_process_child || !LIST_IS_EMPTY(e->inotify_data_buffered))
+        if (event_next_pending(e) || e->need_process_child || e->inotify_data_buffered)
                 goto pending;
 
         e->state = SD_EVENT_ARMED;
@@ -3954,7 +3954,7 @@ static int process_epoll(sd_event *e, usec_t timeout, int64_t threshold, int64_t
         n_event_max = MALLOC_ELEMENTSOF(e->event_queue);
 
         /* If we still have inotify data buffered, then query the other fds, but don't wait on it */
-        if (!LIST_IS_EMPTY(e->inotify_data_buffered))
+        if (e->inotify_data_buffered)
                 timeout = 0;
 
         for (;;) {

src/resolve/resolved-conf.c

@@ -394,7 +394,7 @@ int config_parse_dnssd_txt(
                 last = i;
         }
 
-        if (!LIST_IS_EMPTY(txt_data->txt)) {
+        if (txt_data->txt) {
                 LIST_PREPEND(items, s->txt_data_items, txt_data);
                 TAKE_PTR(txt_data);
         }

src/resolve/resolved-dnssd.c

@@ -107,7 +107,7 @@ static int dnssd_service_load(Manager *manager, const char *filename) {
                                        "%s doesn't define service type",
                                        service->name);
 
-        if (LIST_IS_EMPTY(service->txt_data_items)) {
+        if (!service->txt_data_items) {
                 txt_data = new0(DnssdTxtData, 1);
                 if (!txt_data)
                         return log_oom();

src/test/test-list.c

@@ -240,7 +240,7 @@ int main(int argc, const char *argv[]) {
 
         LIST_JOIN(item, head, head2);
         assert_se(head2 == NULL);
-        assert_se(!LIST_IS_EMPTY(head));
+        assert_se(head);
 
         for (i = 0; i < ELEMENTSOF(items); i++)
                 LIST_REMOVE(item, head, &items[i]);

src/udev/udev-rules.c

@@ -1063,7 +1063,7 @@ static void sort_tokens(UdevRuleLine *rule_line) {
         head_old = TAKE_PTR(rule_line->tokens);
         rule_line->current_token = NULL;
 
-        while (!LIST_IS_EMPTY(head_old)) {
+        while (head_old) {
                 UdevRuleToken *min_token = NULL;
 
                 LIST_FOREACH(tokens, t, head_old)

src/udev/udevd.c

@@ -1008,8 +1008,7 @@ static int event_queue_start(Manager *manager) {
 
         assert(manager);
 
-        if (LIST_IS_EMPTY(manager->events) ||
+        if (!manager->events || manager->exit || manager->stop_exec_queue)
-            manager->exit || manager->stop_exec_queue)
                 return 0;
 
         assert_se(sd_event_now(manager->event, CLOCK_MONOTONIC, &usec) >= 0);
@@ -1166,7 +1165,7 @@ static int event_queue_insert(Manager *manager, sd_device *dev) {
                 .state = EVENT_QUEUED,
         };
 
-        if (LIST_IS_EMPTY(manager->events)) {
+        if (!manager->events) {
                 r = touch("/run/udev/queue");
                 if (r < 0)
                         log_warning_errno(r, "Failed to touch /run/udev/queue, ignoring: %m");
@@ -1611,7 +1610,7 @@ static int on_post(sd_event_source *s, void *userdata) {
 
         assert(manager);
 
-        if (!LIST_IS_EMPTY(manager->events)) {
+        if (manager->events) {
                 /* Try to process pending events if idle workers exist. Why is this necessary?
                  * When a worker finished an event and became idle, even if there was a pending event,
                  * the corresponding device might have been locked and the processing of the event