From f128359332ac33d5ef0c2e91830059fb1c1ef923 Mon Sep 17 00:00:00 2001
From: Kenny Levinsen <kl@kl.wtf>
Date: Tue, 15 Feb 2022 13:24:41 +0100
Subject: logind: Always send ping if data is queued

sd_bus_call_method may have read and queued our ping response, so we
cannot assume that a previous ping will make the socket readable.

Instead, always send a ping if read or write queues are not empty, even
if a ping has already been sent.
---
 libseat/backend/logind.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/libseat/backend/logind.c b/libseat/backend/logind.c
index bfb02cf..53523c8 100644
--- a/libseat/backend/logind.c
+++ b/libseat/backend/logind.c
@@ -41,7 +41,6 @@ struct backend_logind {
 
 	bool active;
 	bool initial_setup;
-	bool awaiting_pong;
 	int has_drm;
 };
 
@@ -70,13 +69,12 @@ static int close_seat(struct libseat *base) {
 
 static int ping_handler(sd_bus_message *m, void *userdata, sd_bus_error *ret_error) {
 	(void)ret_error;
-	struct backend_logind *session = userdata;
+	(void)userdata;
 	if (sd_bus_message_is_method_error(m, NULL)) {
 		const sd_bus_error *error = sd_bus_message_get_error(m);
 		log_errorf("Ping failed: %s: %s", error->name, error->message);
 		return -1;
 	}
-	session->awaiting_pong = false;
 	return 0;
 }
 
@@ -91,14 +89,15 @@ static int send_ping(struct backend_logind *backend) {
 }
 
 static void check_pending_events(struct backend_logind *backend) {
-	if (sd_bus_get_events(backend->bus) <= 0) {
-		return;
-	}
-	if (backend->awaiting_pong) {
+	uint64_t queued_read, queued_write;
+	sd_bus_get_n_queued_read(backend->bus, &queued_read);
+	sd_bus_get_n_queued_write(backend->bus, &queued_write);
+
+	if (queued_read == 0 && queued_write == 0) {
 		return;
 	}
 
-	// We have events pending execution, so a dispatch is required.
+	// The sd_bus instance has queued data, so a dispatch is required.
 	// However, we likely already drained our socket, so there will not be
 	// anything to read. Instead, send a ping request to logind so that the
 	// user will be woken up by its response.
@@ -107,7 +106,6 @@ static void check_pending_events(struct backend_logind *backend) {
 		log_errorf("Could not send ping message: %s", strerror(-ret));
 		return;
 	}
-	backend->awaiting_pong = true;
 }
 
 static int open_device(struct libseat *base, const char *path, int *fd) {
@@ -286,6 +284,7 @@ static int dispatch_and_execute(struct libseat *base, int timeout) {
 			total_dispatched += dispatched;
 		}
 	}
+	check_pending_events(backend);
 	return total_dispatched;
 }
 
@@ -742,6 +741,7 @@ static struct libseat *logind_open_seat(const struct libseat_seat_listener *list
 	backend->seat_listener_data = data;
 	backend->base.impl = &logind_impl;
 
+	check_pending_events(backend);
 	return &backend->base;
 
 error:
-- 
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