Refactor: introduce telinit and a new initctl tool w/ API

- Reduce size of `helpers.c`, for linking against new `initctl` tool,
  by moving out functions to `pid.c` and `exec.c`
- Add `AF_UNIX` API to Finit, to complement old `/dev/initctl` FIFO
- Let old FIFO API be used by init/telinit: `init <q | 1-9>`
- Move all advanced initctl code from `client.c` to `initctl.c`, yes
  its a bit confusing to call the *new* tool the same as the old FIFO
  but this is more in line with what, e.g Upstart does.
- Move all advanced server side code from `plugins/initctl.c` to `api.c`
- Update TODO with upcoming inetd syntax change and dynamic events.
- Temporarily fix display of inetd services from `initctl status -v`

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

inetd.c

@@ -390,6 +390,60 @@ int inetd_match(inetd_t *inetd, char *service, char *proto, char *port)
 	return 0;
 }
 
+/* Compose presentable string of inetd filters: !eth0,eth1,eth2,!eth3 */
+int inetd_filter_str(inetd_t *inetd, char *str, size_t len)
+{
+	int prev = 0;
+	char buf[42];
+	inetd_filter_t *filter;
+
+	if (!inetd || !str || len <= 0) {
+		_e("Dafuq?");
+		return 1;
+	}
+
+	snprintf(str, len, "%s allow ", inetd->name);
+	LIST_FOREACH(filter, &inetd->filters, link) {
+		char ifname[IFNAMSIZ];
+
+		if (filter->deny)
+			continue;
+
+		if (!strlen(filter->ifname))
+			snprintf(ifname, sizeof(ifname), "ANY");
+		else
+			strlcpy(ifname, filter->ifname, sizeof(ifname));
+
+		snprintf(buf, sizeof(buf), "%s%s:%d", prev ? "," : "",
+			 ifname, inetd->port);
+		prev = 1;
+		strlcat(str, buf, len);
+	}
+
+	prev = 0;
+	LIST_FOREACH(filter, &inetd->filters, link) {
+		char ifname[IFNAMSIZ];
+
+		if (!filter->deny)
+			continue;
+		if (!prev) {
+			snprintf(buf, sizeof(buf), " deny ");
+			strlcat(str, buf, len);
+		}
+
+		if (!strlen(filter->ifname))
+			snprintf(ifname, sizeof(ifname), "ANY");
+		else
+			strlcpy(ifname, filter->ifname, sizeof(ifname));
+
+		snprintf(buf, sizeof(buf), "%s%s", prev ? "," : "", ifname);
+		prev = 1;
+		strlcat(str, buf, len);
+	}
+
+	return 0;
+}
+
 /*
  * This function is called to add a new, unique, inetd service.  When an
  * ifname is given as argument this means *only* run service on this