util: make machine_name_is_valid() a macro and move it to hostname-util.h

As it turns out machine_name_is_valid() does the exact same thing as
hostname_is_valid() these days, as it just invoked that and checked the
name length was < 64. However, hostname_is_valid() checks the length
against HOST_NAME_MAX anyway (which is 64 on Linux), hence any
additional check is redundant.

We hence replace machine_name_is_valid() by a macro that simply maps it
to hostname_is_valid() but sets the allow_trailing_dot parameter to
false. We also move this this call to hostname-util.h, to the same place
as the hostname_is_valid() declaration.

src/basic/hostname-util.h

@@ -32,6 +32,8 @@ char* gethostname_malloc(void);
 bool hostname_is_valid(const char *s, bool allow_trailing_dot) _pure_;
 char* hostname_cleanup(char *s);
 
+#define machine_name_is_valid(s) hostname_is_valid(s, false)
+
 bool is_localhost(const char *hostname);
 bool is_gateway_hostname(const char *hostname);
 

src/basic/util.c

@@ -3006,21 +3006,6 @@ char* strshorten(char *s, size_t l) {
         return s;
 }
 
-bool machine_name_is_valid(const char *s) {
-
-        if (!hostname_is_valid(s, false))
-                return false;
-
-        /* Machine names should be useful hostnames, but also be
-         * useful in unit names, hence we enforce a stricter length
-         * limitation. */
-
-        if (strlen(s) > 64)
-                return false;
-
-        return true;
-}
-
 int pipe_eof(int fd) {
         struct pollfd pollfd = {
                 .fd = fd,

src/basic/util.h

@@ -394,8 +394,6 @@ bool nulstr_contains(const char*nulstr, const char *needle);
 
 bool plymouth_running(void);
 
-bool machine_name_is_valid(const char *s) _pure_;
-
 char* strshorten(char *s, size_t l);
 
 int symlink_idempotent(const char *from, const char *to);