testapp: extpoll: add back missing EXTERNAL_POLL pieces

EXTERNAL_POLL is not recommended for use for a while, it's a hack to allow
integration of lws with random application poll() loops.

While lws is very happy to do that secondary job for any event lib using the
foreign loop support (for uv, event, glib, and ev), for random roll-your-
own poll() waits there's no api because there's no event lib.  The solution
with a future is upgrade your application to use an event loop.

The test app that supports EXTERNAL_POLL was broken in Apr 2018, so it's
apparently good news nobody has been using it in new implementations
since then.  This patch adds in the missing pieces so we can test it until
it is formally deprecated.

lib/core-net/service.c

@@ -309,6 +309,15 @@ lws_service_adjust_timeout(struct lws_context *context, int timeout_ms, int tsi)
 
 	pt = &context->pt[tsi];
 
+#if defined(LWS_WITH_EXTERNAL_POLL)
+	{
+		lws_usec_t u = __lws_sul_service_ripe(pt->pt_sul_owner,
+				      LWS_COUNT_PT_SUL_OWNERS, lws_now_usecs());
+		if (u < timeout_ms * 1000)
+			timeout_ms = u / 1000;
+	}
+#endif
+
 	/*
 	 * Figure out if we really want to wait in poll()... we only need to
 	 * wait if really nothing already to do and we have to wait for

test-apps/test-server.c

@@ -55,26 +55,7 @@ char crl_path[1024] = "";
 
 /*
  * This demonstrates how to use the clean protocol service separation of
- * plugins, but with static inclusion instead of runtime dynamic loading
- * (which requires libuv).
- *
- * dumb-increment doesn't use the plugin, both to demonstrate how to
- * do the protocols directly, and because it wants libuv for a timer.
- *
- * Please consider using test-server-v2.0.c instead of this: it has the
- * same functionality but
- *
- * 1) uses lws built-in http handling so you don't need to deal with it in
- * your callback
- *
- * 2) Links with libuv and uses the plugins at runtime
- *
- * 3) Uses advanced lws features like mounts to bind parts of the filesystem
- * to the served URL space
- *
- * Another option is lwsws, this operates like test-server-v2,0.c but is
- * configured using JSON, do you do not need to provide any code for the
- * serving action at all, just implement your protocols in plugins.
+ * plugins, in this case by statically including them at build-time.
  */
 
 #define LWS_PLUGIN_STATIC
@@ -85,15 +66,71 @@ char crl_path[1024] = "";
 #endif
 #include "../plugins/protocol_post_demo.c"
 
+#if defined(LWS_WITH_EXTERNAL_POLL)
+static struct lws_pollfd *
+ext_find_fd(lws_sockfd_type fd)
+{
+	int n;
+
+	for (n = 0; n < max_poll_elements; n++)
+		if (pollfds[n].fd == fd)
+			return &pollfds[n];
+
+	return NULL;
+}
+#endif
+
 static int
 lws_callback_http(struct lws *wsi, enum lws_callback_reasons reason, void *user,
 		  void *in, size_t len)
 {
 	const unsigned char *c;
+#if defined(LWS_WITH_EXTERNAL_POLL)
+	struct lws_pollargs *pa;
+	struct lws_pollfd *pfd;
+#endif
 	char buf[1024];
 	int n = 0, hlen;
 
 	switch (reason) {
+#if defined(LWS_WITH_EXTERNAL_POLL)
+	case LWS_CALLBACK_ADD_POLL_FD:
+		pa = (struct lws_pollargs *)in;
+		lwsl_debug("%s: ADD fd %d, ev %d\n", __func__, pa->fd, pa->events);
+		pfd = ext_find_fd(pa->fd);
+		if (pfd) {
+			lwsl_notice("%s: ADD fd %d already in ext table\n",
+					__func__, pa->fd);
+		} else {
+			pfd = ext_find_fd(LWS_SOCK_INVALID);
+			if (!pfd)
+				return -1;
+		}
+		pfd->fd = pa->fd;
+		pfd->events = pa->events;
+		pfd->revents = 0;
+		/* high water mark... */
+		count_pollfds = (pfd - pollfds) + 1;
+		break;
+	case LWS_CALLBACK_DEL_POLL_FD:
+		pa = (struct lws_pollargs *)in;
+		lwsl_debug("%s: DEL fd %d\n", __func__, pa->fd);
+		pfd = ext_find_fd(pa->fd);
+		if (!pfd)
+			return -1;
+		pfd->fd = LWS_SOCK_INVALID;
+		break;
+	case LWS_CALLBACK_CHANGE_MODE_POLL_FD:
+		pa = (struct lws_pollargs *)in;
+		lwsl_debug("%s: CH fd %d\n", __func__, pa->fd);
+		pfd = ext_find_fd(pa->fd);
+		if (!pfd) {
+			lwsl_err("%s: unknown fd %d\n", __func__, pa->fd);
+			return -1;
+		}
+		pfd->events = pa->events;
+		break;
+#endif
 	case LWS_CALLBACK_HTTP:
 
 		/* non-mount-handled accesses will turn up here */
@@ -501,6 +538,9 @@ int main(int argc, char **argv)
 		lwsl_err("Out of memory pollfds=%d\n", max_poll_elements);
 		return -1;
 	}
+	for (n = 0; n < max_poll_elements; n++)
+		pollfds[n].fd = LWS_SOCK_INVALID;
+	count_pollfds = 0;
 #endif
 
 	info.iface = iface;
@@ -617,7 +657,11 @@ int main(int argc, char **argv)
 		 * this represents an existing server's single poll action
 		 * which also includes libwebsocket sockets
 		 */
-		n = poll(pollfds, count_pollfds, 50);
+
+		/* if needed, force-service wsis that may not have read all input */
+		n = lws_service_adjust_timeout(context, 5000, 0);
+
+		n = poll(pollfds, count_pollfds, n);
 		if (n < 0)
 			continue;
 
@@ -630,15 +674,11 @@ int main(int argc, char **argv)
 					* control
 					*/
 					if (lws_service_fd(context,
-								  &pollfds[n]) < 0)
+							   &pollfds[n]) < 0)
 						goto done;
-
-			/* if needed, force-service wsis that may not have read all input */
-			while (!lws_service_adjust_timeout(context, 1, 0)) {
-				lwsl_notice("extpoll doing forced service!\n");
-				lws_service_tsi(context, -1, 0);
-			}
 		}
+
+		lws_service_tsi(context, -1, 0);
 #else
 		/*
 		 * If libwebsockets sockets are all we care about,