core: rework unit name validation and manipulation logic

A variety of changes:

- Make sure all our calls distuingish OOM from other errors if OOM is
  not the only error possible.

- Be much stricter when parsing escaped paths, do not accept trailing or
  leading escaped slashes.

- Change unit validation to take a bit mask for allowing plain names,
  instance names or template names or an combination thereof.

- Refuse manipulating invalid unit name

12 files changed, 179 insertions, 206 deletions

diff --git a/src/core/automount.c b/src/core/automount.c
index 73b75f163e..1806fa39d3 100644
--- a/src/core/automount.c
+++ b/src/core/automount.c
@@ -167,8 +167,9 @@ static int automount_add_default_dependencies(Automount *a) {
 }
 
 static int automount_verify(Automount *a) {
-        bool b;
         _cleanup_free_ char *e = NULL;
+        int r;
+
         assert(a);
 
         if (UNIT(a)->load_state != UNIT_LOADED)
@@ -179,13 +180,11 @@ static int automount_verify(Automount *a) {
                 return -EINVAL;
         }
 
-        e = unit_name_from_path(a->where, ".automount");
-        if (!e)
-                return -ENOMEM;
-
-        b = unit_has_name(UNIT(a), e);
+        r = unit_name_from_path(a->where, ".automount", &e);
+        if (r < 0)
+                return log_unit_error(UNIT(a)->id, "Failed to generate unit name from path: %m");
 
-        if (!b) {
+        if (!unit_has_name(UNIT(a), e)) {
                 log_unit_error(UNIT(a)->id, "%s's Where setting doesn't match unit name. Refusing.", UNIT(a)->id);
                 return -EINVAL;
         }
@@ -209,9 +208,9 @@ static int automount_load(Unit *u) {
                 Unit *x;
 
                 if (!a->where) {
-                        a->where = unit_name_to_path(u->id);
-                        if (!a->where)
-                                return -ENOMEM;
+                        r = unit_name_to_path(u->id, &a->where);
+                        if (r < 0)
+                                return r;
                 }
 
                 path_kill_slashes(a->where);
diff --git a/src/core/busname.c b/src/core/busname.c
index 20d49fe3e9..8e92fb47fe 100644
--- a/src/core/busname.c
+++ b/src/core/busname.c
@@ -163,9 +163,9 @@ static int busname_add_extras(BusName *n) {
         assert(n);
 
         if (!n->name) {
-                n->name = unit_name_to_prefix(u->id);
-                if (!n->name)
-                        return -ENOMEM;
+                r = unit_name_to_prefix(u->id, &n->name);
+                if (r < 0)
+                        return r;
         }
 
         if (!u->description) {
diff --git a/src/core/dbus-unit.c b/src/core/dbus-unit.c
index 2699e81492..056c7117b2 100644
--- a/src/core/dbus-unit.c
+++ b/src/core/dbus-unit.c
@@ -940,7 +940,7 @@ static int bus_unit_set_transient_property(
                 if (r < 0)
                         return r;
 
-                if (!unit_name_is_valid(s, TEMPLATE_INVALID) || !endswith(s, ".slice"))
+                if (!unit_name_is_valid(s, UNIT_NAME_PLAIN) || !endswith(s, ".slice"))
                         return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid slice name %s", s);
 
                 if (isempty(s)) {
@@ -988,7 +988,7 @@ static int bus_unit_set_transient_property(
                         return r;
 
                 while ((r = sd_bus_message_read(message, "s", &other)) > 0) {
-                        if (!unit_name_is_valid(other, TEMPLATE_INVALID))
+                        if (!unit_name_is_valid(other, UNIT_NAME_PLAIN|UNIT_NAME_INSTANCE))
                                 return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid unit name %s", other);
 
                         if (mode != UNIT_CHECK) {
diff --git a/src/core/device.c b/src/core/device.c
index f8e65b876f..2c56c5a2d2 100644
--- a/src/core/device.c
+++ b/src/core/device.c
@@ -279,9 +279,9 @@ static int device_add_udev_wants(Unit *u, struct udev_device *dev) {
                 memcpy(e, word, l);
                 e[l] = 0;
 
-                n = unit_name_mangle(e, MANGLE_NOGLOB);
-                if (!n)
-                        return log_oom();
+                r = unit_name_mangle(e, UNIT_NAME_NOGLOB, &n);
+                if (r < 0)
+                        return log_unit_error_errno(u->id, r, "Failed to mangle unit name: %m");
 
                 r = unit_add_dependency_by_name(u, UNIT_WANTS, n, NULL, true);
                 if (r < 0)
@@ -308,9 +308,9 @@ static int device_setup_unit(Manager *m, struct udev_device *dev, const char *pa
         if (!sysfs)
                 return 0;
 
-        e = unit_name_from_path(path, ".device");
-        if (!e)
-                return log_oom();
+        r = unit_name_from_path(path, ".device", &e);
+        if (r < 0)
+                return log_unit_error_errno(u->id, r, "Failed to generate device name: %m");
 
         u = manager_get_unit(m, e);
 
@@ -491,6 +491,7 @@ static int device_update_found_by_sysfs(Manager *m, const char *sysfs, bool add,
 static int device_update_found_by_name(Manager *m, const char *path, bool add, DeviceFound found, bool now) {
         _cleanup_free_ char *e = NULL;
         Unit *u;
+        int r;
 
         assert(m);
         assert(path);
@@ -498,9 +499,9 @@ static int device_update_found_by_name(Manager *m, const char *path, bool add, D
         if (found == DEVICE_NOT_FOUND)
                 return 0;
 
-        e = unit_name_from_path(path, ".device");
-        if (!e)
-                return log_oom();
+        r = unit_name_from_path(path, ".device", &e);
+        if (r < 0)
+                return log_error_errno(r, "Failed to generate unit name from device path: %m");
 
         u = manager_get_unit(m, e);
         if (!u)
diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c
index b76656b931..970120ab70 100644
--- a/src/core/load-fragment.c
+++ b/src/core/load-fragment.c
@@ -3394,7 +3394,7 @@ static int open_follow(char **filename, FILE **_f, Set *names, char **_final) {
                  * unit name. */
                 name = basename(*filename);
 
-                if (unit_name_is_valid(name, TEMPLATE_VALID)) {
+                if (unit_name_is_valid(name, UNIT_NAME_ANY)) {
 
                         id = set_get(names, name);
                         if (!id) {
@@ -3642,11 +3642,11 @@ int unit_load_fragment(Unit *u) {
 
         /* Look for a template */
         if (u->load_state == UNIT_STUB && u->instance) {
-                _cleanup_free_ char *k;
+                _cleanup_free_ char *k = NULL;
 
-                k = unit_name_template(u->id);
-                if (!k)
-                        return -ENOMEM;
+                r = unit_name_template(u->id, &k);
+                if (r < 0)
+                        return r;
 
                 r = load_from_path(u, k);
                 if (r < 0)
@@ -3659,9 +3659,9 @@ int unit_load_fragment(Unit *u) {
                                 if (t == u->id)
                                         continue;
 
-                                z = unit_name_template(t);
-                                if (!z)
-                                        return -ENOMEM;
+                                r = unit_name_template(t, &z);
+                                if (r < 0)
+                                        return r;
 
                                 r = load_from_path(u, z);
                                 if (r < 0)
diff --git a/src/core/manager.c b/src/core/manager.c
index b49452151b..8c8645b68d 100644
--- a/src/core/manager.c
+++ b/src/core/manager.c
@@ -1306,7 +1306,7 @@ int manager_load_unit_prepare(
 
         t = unit_name_to_type(name);
 
-        if (t == _UNIT_TYPE_INVALID || !unit_name_is_valid(name, TEMPLATE_INVALID))
+        if (t == _UNIT_TYPE_INVALID || !unit_name_is_valid(name, UNIT_NAME_PLAIN|UNIT_NAME_INSTANCE))
                 return sd_bus_error_setf(e, SD_BUS_ERROR_INVALID_ARGS, "Unit name %s is not valid.", name);
 
         ret = manager_get_unit(m, name);
@@ -2093,7 +2093,7 @@ void manager_send_unit_audit(Manager *m, Unit *u, int type, bool success) {
 #ifdef HAVE_AUDIT
         _cleanup_free_ char *p = NULL;
         const char *msg;
-        int audit_fd;
+        int audit_fd, r;
 
         audit_fd = get_audit_fd();
         if (audit_fd < 0)
@@ -2110,9 +2110,9 @@ void manager_send_unit_audit(Manager *m, Unit *u, int type, bool success) {
         if (u->type != UNIT_SERVICE)
                 return;
 
-        p = unit_name_to_prefix_and_instance(u->id);
-        if (!p) {
-                log_oom();
+        r = unit_name_to_prefix_and_instance(u->id, &p);
+        if (r < 0) {
+                log_error_errno(r, "Failed to extract prefix and instance of unit name: %m");
                 return;
         }
 
@@ -3027,15 +3027,16 @@ void manager_status_printf(Manager *m, StatusType type, const char *status, cons
 int manager_get_unit_by_path(Manager *m, const char *path, const char *suffix, Unit **_found) {
         _cleanup_free_ char *p = NULL;
         Unit *found;
+        int r;
 
         assert(m);
         assert(path);
         assert(suffix);
         assert(_found);
 
-        p = unit_name_from_path(path, suffix);
-        if (!p)
-                return -ENOMEM;
+        r = unit_name_from_path(path, suffix, &p);
+        if (r < 0)
+                return r;
 
         found = manager_get_unit(m, p);
         if (!found) {
diff --git a/src/core/mount.c b/src/core/mount.c
index d0c41a73a9..65a66b468f 100644
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -435,7 +435,7 @@ static int mount_add_default_dependencies(Mount *m) {
 
 static int mount_verify(Mount *m) {
         _cleanup_free_ char *e = NULL;
-        bool b;
+        int r;
 
         assert(m);
 
@@ -445,12 +445,11 @@ static int mount_verify(Mount *m) {
         if (!m->from_fragment && !m->from_proc_self_mountinfo)
                 return -ENOENT;
 
-        e = unit_name_from_path(m->where, ".mount");
-        if (!e)
-                return -ENOMEM;
+        r = unit_name_from_path(m->where, ".mount", &e);
+        if (r < 0)
+                return log_unit_error_errno(UNIT(m)->id, r, "Failed to generate unit name from mount path: %m");
 
-        b = unit_has_name(UNIT(m), e);
-        if (!b) {
+        if (!unit_has_name(UNIT(m), e)) {
                 log_unit_error(UNIT(m)->id, "%s's Where= setting doesn't match unit name. Refusing.", UNIT(m)->id);
                 return -EINVAL;
         }
@@ -483,9 +482,9 @@ static int mount_add_extras(Mount *m) {
                 m->from_fragment = true;
 
         if (!m->where) {
-                m->where = unit_name_to_path(u->id);
-                if (!m->where)
-                        return -ENOMEM;
+                r = unit_name_to_path(u->id, &m->where);
+                if (r < 0)
+                        return r;
         }
 
         path_kill_slashes(m->where);
@@ -1419,9 +1418,9 @@ static int mount_setup_unit(
         if (!is_path(where))
                 return 0;
 
-        e = unit_name_from_path(where, ".mount");
-        if (!e)
-                return -ENOMEM;
+        r = unit_name_from_path(where, ".mount", &e);
+        if (r < 0)
+                return r;
 
         u = manager_get_unit(m, e);
         if (!u) {
diff --git a/src/core/snapshot.c b/src/core/snapshot.c
index b70c3beb60..2c00680f16 100644
--- a/src/core/snapshot.c
+++ b/src/core/snapshot.c
@@ -201,10 +201,10 @@ int snapshot_create(Manager *m, const char *name, bool cleanup, sd_bus_error *e,
         assert(_s);
 
         if (name) {
-                if (!unit_name_is_valid(name, TEMPLATE_INVALID))
+                if (!unit_name_is_valid(name, UNIT_NAME_PLAIN))
                         return sd_bus_error_setf(e, SD_BUS_ERROR_INVALID_ARGS, "Unit name %s is not valid.", name);
 
-                if (unit_name_to_type(name) != UNIT_SNAPSHOT)
+                if (!endswith(name, ".snapshot"))
                         return sd_bus_error_setf(e, SD_BUS_ERROR_INVALID_ARGS, "Unit name %s lacks snapshot suffix.", name);
 
                 if (manager_get_unit(m, name))
diff --git a/src/core/socket.c b/src/core/socket.c
index 67beda44d6..55334e4a54 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -196,12 +196,15 @@ int socket_instantiate_service(Socket *s) {
          * here. For Accept=no this is mostly a NOP since the service
          * is figured out at load time anyway. */
 
-        if (UNIT_DEREF(s->service) || !s->accept)
+        if (UNIT_DEREF(s->service))
                 return 0;
 
-        prefix = unit_name_to_prefix(UNIT(s)->id);
-        if (!prefix)
-                return -ENOMEM;
+        if (!s->accept)
+                return 0;
+
+        r = unit_name_to_prefix(UNIT(s)->id, &prefix);
+        if (r < 0)
+                return r;
 
         if (asprintf(&name, "%s@%u.service", prefix, s->n_accepted) < 0)
                 return -ENOMEM;
@@ -1836,17 +1839,13 @@ static void socket_enter_running(Socket *s, int cfd) {
                         return;
                 }
 
-                prefix = unit_name_to_prefix(UNIT(s)->id);
-                if (!prefix) {
-                        r = -ENOMEM;
+                r = unit_name_to_prefix(UNIT(s)->id, &prefix);
+                if (r < 0)
                         goto fail;
-                }
 
-                name = unit_name_build(prefix, instance, ".service");
-                if (!name) {
-                        r = -ENOMEM;
+                r = unit_name_build(prefix, instance, ".service", &name);
+                if (r < 0)
                         goto fail;
-                }
 
                 r = unit_add_name(UNIT_DEREF(s->service), name);
                 if (r < 0)
diff --git a/src/core/swap.c b/src/core/swap.c
index a9834a7fe5..3327cd958f 100644
--- a/src/core/swap.c
+++ b/src/core/swap.c
@@ -222,18 +222,17 @@ static int swap_add_default_dependencies(Swap *s) {
 }
 
 static int swap_verify(Swap *s) {
-        bool b;
         _cleanup_free_ char *e = NULL;
+        int r;
 
         if (UNIT(s)->load_state != UNIT_LOADED)
                 return 0;
 
-        e = unit_name_from_path(s->what, ".swap");
-        if (!e)
-                return log_oom();
+        r = unit_name_from_path(s->what, ".swap", &e);
+        if (r < 0)
+                return log_unit_error_errno(UNIT(s)->id, r, "%s: failed to generate unit name from path: %m", UNIT(s)->id);
 
-        b = unit_has_name(UNIT(s), e);
-        if (!b) {
+        if (!unit_has_name(UNIT(s), e)) {
                 log_unit_error(UNIT(s)->id, "%s: Value of \"What\" and unit name do not match, not loading.", UNIT(s)->id);
                 return -EINVAL;
         }
@@ -289,8 +288,11 @@ static int swap_load(Unit *u) {
                                 s->what = strdup(s->parameters_fragment.what);
                         else if (s->parameters_proc_swaps.what)
                                 s->what = strdup(s->parameters_proc_swaps.what);
-                        else
-                                s->what = unit_name_to_path(u->id);
+                        else {
+                                r = unit_name_to_path(u->id, &s->what);
+                                if (r < 0)
+                                        return r;
+                        }
 
                         if (!s->what)
                                 return -ENOMEM;
@@ -355,9 +357,9 @@ static int swap_setup_unit(
         assert(what);
         assert(what_proc_swaps);
 
-        e = unit_name_from_path(what, ".swap");
-        if (!e)
-                return log_oom();
+        r = unit_name_from_path(what, ".swap", &e);
+        if (r < 0)
+                return log_unit_error_errno(u->id, r, "Failed to generate unit name from path: %m");
 
         u = manager_get_unit(m, e);
 
@@ -1329,9 +1331,9 @@ int swap_process_device_new(Manager *m, struct udev_device *dev) {
         if (!dn)
                 return 0;
 
-        e = unit_name_from_path(dn, ".swap");
-        if (!e)
-                return -ENOMEM;
+        r = unit_name_from_path(dn, ".swap", &e);
+        if (r < 0)
+                return r;
 
         s = hashmap_get(m->units, e);
         if (s)
@@ -1340,15 +1342,14 @@ int swap_process_device_new(Manager *m, struct udev_device *dev) {
         first = udev_device_get_devlinks_list_entry(dev);
         udev_list_entry_foreach(item, first) {
                 _cleanup_free_ char *n = NULL;
+                int q;
 
-                n = unit_name_from_path(udev_list_entry_get_name(item), ".swap");
-                if (!n)
-                        return -ENOMEM;
+                q = unit_name_from_path(udev_list_entry_get_name(item), ".swap", &n);
+                if (q < 0)
+                        return q;
 
                 s = hashmap_get(m->units, n);
                 if (s) {
-                        int q;
-
                         q = swap_set_devnode(s, dn);
                         if (q < 0)
                                 r = q;
diff --git a/src/core/unit-printf.c b/src/core/unit-printf.c
index 5513fe7d9c..8050e2fd66 100644
--- a/src/core/unit-printf.c
+++ b/src/core/unit-printf.c
@@ -30,83 +30,54 @@
 
 static int specifier_prefix_and_instance(char specifier, void *data, void *userdata, char **ret) {
         Unit *u = userdata;
-        char *n;
 
         assert(u);
 
-        n = unit_name_to_prefix_and_instance(u->id);
-        if (!n)
-                return -ENOMEM;
-
-        *ret = n;
-        return 0;
+        return unit_name_to_prefix_and_instance(u->id, ret);
 }
 
 static int specifier_prefix(char specifier, void *data, void *userdata, char **ret) {
         Unit *u = userdata;
-        char *n;
 
         assert(u);
 
-        n = unit_name_to_prefix(u->id);
-        if (!n)
-                return -ENOMEM;
-
-        *ret = n;
-        return 0;
+        return unit_name_to_prefix(u->id, ret);
 }
 
 static int specifier_prefix_unescaped(char specifier, void *data, void *userdata, char **ret) {
-        Unit *u = userdata;
         _cleanup_free_ char *p = NULL;
-        char *n;
+        Unit *u = userdata;
+        int r;
 
         assert(u);
 
-        p = unit_name_to_prefix(u->id);
-        if (!p)
-                return -ENOMEM;
-
-        n = unit_name_unescape(p);
-        if (!n)
-                return -ENOMEM;
+        r = unit_name_to_prefix(u->id, &p);
+        if (r < 0)
+                return r;
 
-        *ret = n;
-        return 0;
+        return unit_name_unescape(p, ret);
 }
 
 static int specifier_instance_unescaped(char specifier, void *data, void *userdata, char **ret) {
         Unit *u = userdata;
-        char *n;
 
         assert(u);
 
         if (!u->instance)
-                return -EOPNOTSUPP;
-
-        n = unit_name_unescape(u->instance);
-        if (!n)
-                return -ENOMEM;
+                return -EINVAL;
 
-        *ret = n;
-        return 0;
+        return unit_name_unescape(u->instance, ret);
 }
 
 static int specifier_filename(char specifier, void *data, void *userdata, char **ret) {
         Unit *u = userdata;
-        char *n;
 
         assert(u);
 
         if (u->instance)
-                n = unit_name_path_unescape(u->instance);
+                return unit_name_path_unescape(u->instance, ret);
         else
-                n = unit_name_to_path(u->id);
-        if (!n)
-                return -ENOMEM;
-
-        *ret = n;
-        return 0;
+                return unit_name_to_path(u->id, ret);
 }
 
 static int specifier_cgroup(char specifier, void *data, void *userdata, char **ret) {
@@ -195,7 +166,7 @@ static int specifier_user_name(char specifier, void *data, void *userdata, char
 
         c = unit_get_exec_context(u);
         if (!c)
-                return -EOPNOTSUPP;
+                return -EINVAL;
 
         if (u->manager->running_as == SYSTEMD_SYSTEM) {
 
diff --git a/src/core/unit.c b/src/core/unit.c
index 6071bd51b1..6513bcb1cb 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -143,21 +143,31 @@ int unit_add_name(Unit *u, const char *text) {
         assert(u);
         assert(text);
 
-        if (unit_name_is_template(text)) {
+        if (unit_name_is_valid(text, UNIT_NAME_TEMPLATE)) {
 
                 if (!u->instance)
                         return -EINVAL;
 
-                s = unit_name_replace_instance(text, u->instance);
-        } else
+                r = unit_name_replace_instance(text, u->instance, &s);
+                if (r < 0)
+                        return r;
+        } else {
                 s = strdup(text);
-        if (!s)
-                return -ENOMEM;
+                if (!s)
+                        return -ENOMEM;
+        }
 
-        if (!unit_name_is_valid(s, TEMPLATE_INVALID))
+        if (set_contains(u->names, s))
+                return 0;
+        if (hashmap_contains(u->manager->units, s))
+                return -EEXIST;
+
+        if (!unit_name_is_valid(s, UNIT_NAME_PLAIN|UNIT_NAME_INSTANCE))
                 return -EINVAL;
 
-        assert_se((t = unit_name_to_type(s)) >= 0);
+        t = unit_name_to_type(s);
+        if (t < 0)
+                return -EINVAL;
 
         if (u->type != _UNIT_TYPE_INVALID && t != u->type)
                 return -EINVAL;
@@ -170,25 +180,25 @@ int unit_add_name(Unit *u, const char *text) {
                 return -EINVAL;
 
         /* Ensure that this unit is either instanced or not instanced,
-         * but not both. */
+         * but not both. Note that we do allow names with different
+         * instance names however! */
         if (u->type != _UNIT_TYPE_INVALID && !u->instance != !i)
                 return -EINVAL;
 
-        if (unit_vtable[t]->no_alias &&
-            !set_isempty(u->names) &&
-            !set_get(u->names, s))
+        if (unit_vtable[t]->no_alias && !set_isempty(u->names))
                 return -EEXIST;
 
         if (hashmap_size(u->manager->units) >= MANAGER_MAX_NAMES)
                 return -E2BIG;
 
         r = set_put(u->names, s);
-        if (r <= 0)
+        if (r < 0)
                 return r;
+        assert(r > 0);
 
         r = hashmap_put(u->manager->units, s, u);
         if (r < 0) {
-                set_remove(u->names, s);
+                (void) set_remove(u->names, s);
                 return r;
         }
 
@@ -218,14 +228,14 @@ int unit_choose_id(Unit *u, const char *name) {
         assert(u);
         assert(name);
 
-        if (unit_name_is_template(name)) {
+        if (unit_name_is_valid(name, UNIT_NAME_TEMPLATE)) {
 
                 if (!u->instance)
                         return -EINVAL;
 
-                t = unit_name_replace_instance(name, u->instance);
-                if (!t)
-                        return -ENOMEM;
+                r = unit_name_replace_instance(name, u->instance, &t);
+                if (r < 0)
+                        return r;
 
                 name = t;
         }
@@ -235,6 +245,7 @@ int unit_choose_id(Unit *u, const char *name) {
         if (!s)
                 return -ENOENT;
 
+        /* Determine the new instance from the new id */
         r = unit_name_to_instance(s, &i);
         if (r < 0)
                 return r;
@@ -748,24 +759,22 @@ int unit_merge_by_name(Unit *u, const char *name) {
         assert(u);
         assert(name);
 
-        if (unit_name_is_template(name)) {
+        if (unit_name_is_valid(name, UNIT_NAME_TEMPLATE)) {
                 if (!u->instance)
                         return -EINVAL;
 
-                s = unit_name_replace_instance(name, u->instance);
-                if (!s)
-                        return -ENOMEM;
+                r = unit_name_replace_instance(name, u->instance, &s);
+                if (r < 0)
+                        return r;
 
                 name = s;
         }
 
         other = manager_get_unit(u->manager, name);
-        if (!other)
-                r = unit_add_name(u, name);
-        else
-                r = unit_merge(u, other);
+        if (other)
+                return unit_merge(u, other);
 
-        return r;
+        return unit_add_name(u, name);
 }
 
 Unit* unit_follow_merge(Unit *u) {
@@ -2294,58 +2303,55 @@ int unit_add_two_dependencies(Unit *u, UnitDependency d, UnitDependency e, Unit
         if (r < 0)
                 return r;
 
-        r = unit_add_dependency(u, e, other, add_reference);
-        if (r < 0)
-                return r;
-
-        return 0;
+        return unit_add_dependency(u, e, other, add_reference);
 }
 
-static const char *resolve_template(Unit *u, const char *name, const char*path, char **p) {
-        char *s;
+static int resolve_template(Unit *u, const char *name, const char*path, char **buf, const char **ret) {
+        int r;
 
         assert(u);
         assert(name || path);
-        assert(p);
+        assert(buf);
+        assert(ret);
 
         if (!name)
                 name = basename(path);
 
-        if (!unit_name_is_template(name)) {
-                *p = NULL;
-                return name;
+        if (!unit_name_is_valid(name, UNIT_NAME_TEMPLATE)) {
+                *buf = NULL;
+                *ret = name;
+                return 0;
         }
 
         if (u->instance)
-                s = unit_name_replace_instance(name, u->instance);
+                r = unit_name_replace_instance(name, u->instance, buf);
         else {
                 _cleanup_free_ char *i = NULL;
 
-                i = unit_name_to_prefix(u->id);
-                if (!i)
-                        return NULL;
+                r = unit_name_to_prefix(u->id, &i);
+                if (r < 0)
+                        return r;
 
-                s = unit_name_replace_instance(name, i);
+                r = unit_name_replace_instance(name, i, buf);
         }
+        if (r < 0)
+                return r;
 
-        if (!s)
-                return NULL;
-
-        *p = s;
-        return s;
+        *ret = *buf;
+        return 0;
 }
 
 int unit_add_dependency_by_name(Unit *u, UnitDependency d, const char *name, const char *path, bool add_reference) {
+        _cleanup_free_ char *buf = NULL;
         Unit *other;
         int r;
-        _cleanup_free_ char *s = NULL;
 
         assert(u);
         assert(name || path);
 
-        name = resolve_template(u, name, path, &s);
-        if (!name)
-                return -ENOMEM;
+        r = resolve_template(u, name, path, &buf, &name);
+        if (r < 0)
+                return r;
 
         r = manager_load_unit(u->manager, name, path, NULL, &other);
         if (r < 0)
@@ -2355,16 +2361,16 @@ int unit_add_dependency_by_name(Unit *u, UnitDependency d, const char *name, con
 }
 
 int unit_add_two_dependencies_by_name(Unit *u, UnitDependency d, UnitDependency e, const char *name, const char *path, bool add_reference) {
-        _cleanup_free_ char *s = NULL;
+        _cleanup_free_ char *buf = NULL;
         Unit *other;
         int r;
 
         assert(u);
         assert(name || path);
 
-        name = resolve_template(u, name, path, &s);
-        if (!name)
-                return -ENOMEM;
+        r = resolve_template(u, name, path, &buf, &name);
+        if (r < 0)
+                return r;
 
         r = manager_load_unit(u->manager, name, path, NULL, &other);
         if (r < 0)
@@ -2374,16 +2380,16 @@ int unit_add_two_dependencies_by_name(Unit *u, UnitDependency d, UnitDependency
 }
 
 int unit_add_dependency_by_name_inverse(Unit *u, UnitDependency d, const char *name, const char *path, bool add_reference) {
+        _cleanup_free_ char *buf = NULL;
         Unit *other;
         int r;
-        _cleanup_free_ char *s = NULL;
 
         assert(u);
         assert(name || path);
 
-        name = resolve_template(u, name, path, &s);
-        if (!name)
-                return -ENOMEM;
+        r = resolve_template(u, name, path, &buf, &name);
+        if (r < 0)
+                return r;
 
         r = manager_load_unit(u->manager, name, path, NULL, &other);
         if (r < 0)
@@ -2393,26 +2399,22 @@ int unit_add_dependency_by_name_inverse(Unit *u, UnitDependency d, const char *n
 }
 
 int unit_add_two_dependencies_by_name_inverse(Unit *u, UnitDependency d, UnitDependency e, const char *name, const char *path, bool add_reference) {
+        _cleanup_free_ char *buf = NULL;
         Unit *other;
         int r;
-        _cleanup_free_ char *s = NULL;
 
         assert(u);
         assert(name || path);
 
-        name = resolve_template(u, name, path, &s);
-        if (!name)
-                return -ENOMEM;
-
-        r = manager_load_unit(u->manager, name, path, NULL, &other);
+        r  = resolve_template(u, name, path, &buf, &name);
         if (r < 0)
                 return r;
 
-        r = unit_add_two_dependencies(other, d, e, u, add_reference);
+        r = manager_load_unit(u->manager, name, path, NULL, &other);
         if (r < 0)
                 return r;
 
-        return r;
+        return unit_add_two_dependencies(other, d, e, u, add_reference);
 }
 
 int set_unit_path(const char *p) {
@@ -2475,14 +2477,14 @@ int unit_add_default_slice(Unit *u, CGroupContext *c) {
                 /* Implicitly place all instantiated units in their
                  * own per-template slice */
 
-                prefix = unit_name_to_prefix(u->id);
-                if (!prefix)
-                        return -ENOMEM;
+                r = unit_name_to_prefix(u->id, &prefix);
+                if (r < 0)
+                        return r;
 
                 /* The prefix is already escaped, but it might include
                  * "-" which has a special meaning for slice units,
                  * hence escape it here extra. */
-                escaped = strreplace(prefix, "-", "\\x2d");
+                escaped = unit_name_escape(prefix);
                 if (!escaped)
                         return -ENOMEM;
 
@@ -2525,11 +2527,11 @@ int unit_load_related_unit(Unit *u, const char *type, Unit **_found) {
         assert(type);
         assert(_found);
 
-        t = unit_name_change_suffix(u->id, type);
-        if (!t)
-                return -ENOMEM;
-
-        assert(!unit_has_name(u, t));
+        r = unit_name_change_suffix(u->id, type, &t);
+        if (r < 0)
+                return r;
+        if (unit_has_name(u, t))
+                return -EINVAL;
 
         r = manager_load_unit(u->manager, t, NULL, NULL, _found);
         assert(r < 0 || *_found != u);
@@ -2858,9 +2860,9 @@ int unit_add_node_link(Unit *u, const char *what, bool wants) {
         if (!unit_type_supported(UNIT_DEVICE))
                 return 0;
 
-        e = unit_name_from_path(what, ".device");
-        if (!e)
-                return -ENOMEM;
+        r = unit_name_from_path(what, ".device", &e);
+        if (r < 0)
+                return r;
 
         r = manager_load_unit(u->manager, e, NULL, NULL, &device);
         if (r < 0)