core: turn unit_load_fragment_and_dropin_optional() into a flag

unit_load_fragment_and_dropin() and unit_load_fragment_and_dropin_optional()
are really the same, with one minor difference in behaviour. Let's drop
the second function.

"_optional" in the name suggests that it's the "dropin" part that is optional.
(Which it is, but in this case, we mean the fragment to be optional.)
I think the new version with a flag is easier to understand.

src/core/automount.c

@@ -209,7 +209,7 @@ static int automount_load(Unit *u) {
         assert(u->load_state == UNIT_STUB);
 
         /* Load a .automount file */
-        r = unit_load_fragment_and_dropin(u);
+        r = unit_load_fragment_and_dropin(u, true);
         if (r < 0)
                 return r;
 

src/core/device.c

@@ -116,7 +116,7 @@ static void device_done(Unit *u) {
 static int device_load(Unit *u) {
         int r;
 
-        r = unit_load_fragment_and_dropin_optional(u);
+        r = unit_load_fragment_and_dropin(u, false);
         if (r < 0)
                 return r;
 

src/core/mount.c

@@ -634,10 +634,8 @@ static int mount_load(Unit *u) {
 
         r = mount_load_root_mount(u);
 
-        if (m->from_proc_self_mountinfo || u->perpetual)
-                q = unit_load_fragment_and_dropin_optional(u);
-        else
-                q = unit_load_fragment_and_dropin(u);
+        bool fragment_optional = m->from_proc_self_mountinfo || u->perpetual;
+        q = unit_load_fragment_and_dropin(u, !fragment_optional);
 
         /* Add in some extras. Note we do this in all cases (even if we failed to load the unit) when announced by the
          * kernel, because we need some things to be set up no matter what when the kernel establishes a mount and thus

src/core/path.c

@@ -340,7 +340,7 @@ static int path_load(Unit *u) {
         assert(u);
         assert(u->load_state == UNIT_STUB);
 
-        r = unit_load_fragment_and_dropin(u);
+        r = unit_load_fragment_and_dropin(u, true);
         if (r < 0)
                 return r;
 

src/core/scope.c

@@ -176,7 +176,8 @@ static int scope_load(Unit *u) {
         r = scope_load_init_scope(u);
         if (r < 0)
                 return r;
-        r = unit_load_fragment_and_dropin_optional(u);
+
+        r = unit_load_fragment_and_dropin(u, false);
         if (r < 0)
                 return r;
 

src/core/slice.c

@@ -170,7 +170,7 @@ static int slice_load(Unit *u) {
         if (r < 0)
                 return r;
 
-        r = unit_load_fragment_and_dropin_optional(u);
+        r = unit_load_fragment_and_dropin(u, false);
         if (r < 0)
                 return r;
 

src/core/socket.c

@@ -514,7 +514,7 @@ static int socket_load(Unit *u) {
         if (r < 0)
                 return r;
 
-        r = unit_load_fragment_and_dropin(u);
+        r = unit_load_fragment_and_dropin(u, true);
         if (r < 0)
                 return r;
 

src/core/swap.c

@@ -346,10 +346,8 @@ static int swap_load(Unit *u) {
         assert(u->load_state == UNIT_STUB);
 
         /* Load a .swap file */
-        if (SWAP(u)->from_proc_swaps)
-                r = unit_load_fragment_and_dropin_optional(u);
-        else
-                r = unit_load_fragment_and_dropin(u);
+        bool fragment_optional = s->from_proc_swaps;
+        r = unit_load_fragment_and_dropin(u, !fragment_optional);
 
         /* Add in some extras, and do so either when we successfully loaded something or when /proc/swaps is already
          * active. */

src/core/target.c

@@ -80,7 +80,7 @@ static int target_load(Unit *u) {
 
         assert(t);
 
-        r = unit_load_fragment_and_dropin(u);
+        r = unit_load_fragment_and_dropin(u, true);
         if (r < 0)
                 return r;
 

src/core/timer.c

@@ -178,7 +178,7 @@ static int timer_load(Unit *u) {
         assert(u);
         assert(u->load_state == UNIT_STUB);
 
-        r = unit_load_fragment_and_dropin(u);
+        r = unit_load_fragment_and_dropin(u, true);
         if (r < 0)
                 return r;
 

src/core/unit.c

@@ -1361,7 +1361,7 @@ void unit_dump(Unit *u, FILE *f, const char *prefix) {
 }
 
 /* Common implementation for multiple backends */
-int unit_load_fragment_and_dropin(Unit *u) {
+int unit_load_fragment_and_dropin(Unit *u, bool fragment_required) {
         int r;
 
         assert(u);
@@ -1371,8 +1371,12 @@ int unit_load_fragment_and_dropin(Unit *u) {
         if (r < 0)
                 return r;
 
-        if (u->load_state == UNIT_STUB)
-                return -ENOENT;
+        if (u->load_state == UNIT_STUB) {
+                if (fragment_required)
+                        return -ENOENT;
+
+                u->load_state = UNIT_LOADED;
+        }
 
         /* Load drop-in directory data. If u is an alias, we might be reloading the
          * target unit needlessly. But we cannot be sure which drops-ins have already
@@ -1381,27 +1385,6 @@ int unit_load_fragment_and_dropin(Unit *u) {
         return unit_load_dropin(unit_follow_merge(u));
 }
 
-/* Common implementation for multiple backends */
-int unit_load_fragment_and_dropin_optional(Unit *u) {
-        int r;
-
-        assert(u);
-
-        /* Same as unit_load_fragment_and_dropin(), but whether
-         * something can be loaded or not doesn't matter. */
-
-        /* Load a .service/.socket/.slice/… file */
-        r = unit_load_fragment(u);
-        if (r < 0)
-                return r;
-
-        if (u->load_state == UNIT_STUB)
-                u->load_state = UNIT_LOADED;
-
-        /* Load drop-in directory data */
-        return unit_load_dropin(unit_follow_merge(u));
-}
-
 void unit_add_to_target_deps_queue(Unit *u) {
         Manager *m = u->manager;
 

src/core/unit.h

@@ -670,8 +670,7 @@ int unit_merge_by_name(Unit *u, const char *other);
 
 Unit *unit_follow_merge(Unit *u) _pure_;
 
-int unit_load_fragment_and_dropin(Unit *u);
-int unit_load_fragment_and_dropin_optional(Unit *u);
+int unit_load_fragment_and_dropin(Unit *u, bool fragment_required);
 int unit_load(Unit *unit);
 
 int unit_set_slice(Unit *u, Unit *slice);