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

1 files changed, 4 insertions, 4 deletions

diff --git a/src/login/logind-user.c b/src/login/logind-user.c
index b00e9b17dc..71bff96728 100644
--- a/src/login/logind-user.c
+++ b/src/login/logind-user.c
@@ -378,7 +378,7 @@ static int user_start_slice(User *u) {
                 char lu[DECIMAL_STR_MAX(uid_t) + 1], *slice;
                 sprintf(lu, UID_FMT, u->uid);
 
-                r = build_subslice(SPECIAL_USER_SLICE, lu, &slice);
+                r = slice_build_subslice(SPECIAL_USER_SLICE, lu, &slice);
                 if (r < 0)
                         return r;
 
@@ -411,9 +411,9 @@ static int user_start_service(User *u) {
                 char lu[DECIMAL_STR_MAX(uid_t) + 1], *service;
                 sprintf(lu, UID_FMT, u->uid);
 
-                service = unit_name_build("user", lu, ".service");
-                if (!service)
-                        return log_oom();
+                r = unit_name_build("user", lu, ".service", &service);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to build service name: %m");
 
                 r = manager_start_unit(u->manager, service, &error, &job);
                 if (r < 0) {