dnsdomainname: split it from "hostname", make it independently selectable

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

networking/Config.src

@@ -160,12 +160,6 @@ config FEATURE_FTPGETPUT_LONG_OPTIONS
 	help
 	  Support long options for the ftpget/ftpput applet.
 
-config HOSTNAME
-	bool "hostname"
-	default y
-	help
-	  Show or set the system's host name.
-
 config HTTPD
 	bool "httpd"
 	default y

networking/Kbuild.src

@@ -16,7 +16,6 @@ lib-$(CONFIG_FAKEIDENTD)   += isrv_identd.o isrv.o
 lib-$(CONFIG_FTPD)         += ftpd.o
 lib-$(CONFIG_FTPGET)       += ftpgetput.o
 lib-$(CONFIG_FTPPUT)       += ftpgetput.o
-lib-$(CONFIG_HOSTNAME)     += hostname.o
 lib-$(CONFIG_HTTPD)        += httpd.o
 lib-$(CONFIG_IFCONFIG)     += ifconfig.o interface.o
 lib-$(CONFIG_IFENSLAVE)    += ifenslave.o interface.o

networking/hostname.c

@@ -10,6 +10,24 @@
  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 
+//config:config HOSTNAME
+//config:	bool "hostname"
+//config:	default y
+//config:	help
+//config:	  Show or set the system's host name.
+//config:
+//config:config DNSDOMAINNAME
+//config:	bool "dnsdomainname"
+//config:	default y
+//config:	help
+//config:	  Alias to "hostname -d".
+
+//applet:IF_DNSDOMAINNAME(APPLET_ODDNAME(dnsdomainname, hostname, BB_DIR_BIN, BB_SUID_DROP, dnsdomainname))
+//applet:IF_HOSTNAME(APPLET(hostname, BB_DIR_BIN, BB_SUID_DROP))
+
+//kbuild: lib-$(CONFIG_HOSTNAME) += hostname.o
+//kbuild: lib-$(CONFIG_DNSDOMAINNAME) += hostname.o
+
 //usage:#define hostname_trivial_usage
 //usage:       "[OPTIONS] [HOSTNAME | -F FILE]"
 //usage:#define hostname_full_usage "\n\n"
@@ -131,8 +149,12 @@ int hostname_main(int argc UNUSED_PARAM, char **argv)
 	opts = getopt32(argv, "dfisF:v", &hostname_str);
 	argv += optind;
 	buf = safe_gethostname();
-	if (applet_name[0] == 'd') /* dnsdomainname? */
-		opts = OPT_d;
+	if (ENABLE_DNSDOMAINNAME) {
+		if (!ENABLE_HOSTNAME || applet_name[0] == 'd') {
+			/* dnsdomainname */
+			opts = OPT_d;
+		}
+	}
 
 	if (opts & OPT_dfi) {
 		/* Cases when we need full hostname (or its part) */