logind: extract has_vts() from can_multi_session()

We currently use seat_can_multi_session() to test for two things:
 * whether the seat can handle session-switching
 * whether the seat has VTs

As both are currently logically equivalent, we didn't care. However, we
want to allow session-switching on seats without VTs, so split this helper
into:
 * seat_can_multi_session(): whether session-switching is supported
 * seat_has_vts(): whether the seat has VTs

Note that only one seat on a system can have VTs. There is only one set of
them. We automatically assign them to seat0 as usual.

With this patch in place, we can easily add new session-switching/tracking
methods without breaking any VT code as it is now protected by has_vts(),
no longer by can_multi_session().

1 files changed, 3 insertions, 3 deletions

diff --git a/src/login/logind-session.c b/src/login/logind-session.c
index ab1c79cfa2..f856127eae 100644
--- a/src/login/logind-session.c
+++ b/src/login/logind-session.c
@@ -191,7 +191,7 @@ int session_save(Session *s) {
         if (s->service)
                 fprintf(f, "SERVICE=%s\n", s->service);
 
-        if (s->seat && seat_can_multi_session(s->seat))
+        if (s->seat && seat_has_vts(s->seat))
                 fprintf(f, "VTNR=%i\n", s->vtnr);
 
         if (s->leader > 0)
@@ -301,7 +301,7 @@ int session_load(Session *s) {
                         seat_attach_session(o, s);
         }
 
-        if (vtnr && s->seat && seat_can_multi_session(s->seat)) {
+        if (vtnr && s->seat && seat_has_vts(s->seat)) {
                 int v;
 
                 k = safe_atoi(vtnr, &v);
@@ -372,7 +372,7 @@ int session_activate(Session *s) {
         if (s->seat->active == s)
                 return 0;
 
-        assert(seat_is_seat0(s->seat));
+        assert(seat_has_vts(s->seat));
 
         return chvt(s->vtnr);
 }