hostname-setup: also consider (ńone) an unset hostname

src/shared/util.c

@@ -2949,12 +2949,20 @@ char* gethostname_malloc(void) {
 
         assert_se(uname(&u) >= 0);
 
-        if (u.nodename[0])
+        if (!isempty(u.nodename) && !streq(u.nodename, "(none)"))
                 return strdup(u.nodename);
 
         return strdup(u.sysname);
 }
 
+bool hostname_is_set(void) {
+        struct utsname u;
+
+        assert_se(uname(&u) >= 0);
+
+        return !isempty(u.nodename) && !streq(u.nodename, "(none)");
+}
+
 char* getlogname_malloc(void) {
         uid_t uid;
         long bufsize;

src/shared/util.h

@@ -337,6 +337,7 @@ void rename_process(const char name[8]);
 void sigset_add_many(sigset_t *ss, ...);
 
 char* gethostname_malloc(void);
+bool hostname_is_set(void);
 char* getlogname_malloc(void);
 
 int getttyname_malloc(int fd, char **r);