PoC: Use udev polling of netlink kernel events for battery plugging e…

…vents

src/modules/battery.cpp

@@ -5,6 +5,8 @@
 #include <sys/sysctl.h>
 #endif
 #include <spdlog/spdlog.h>
+#include <libudev.h>
+#include <poll.h>
 
 #include <iostream>
 waybar::modules::Battery::Battery(const std::string& id, const Bar& bar, const Json::Value& config)
@@ -74,12 +76,40 @@ void waybar::modules::Battery::worker() {
     dp.emit();
   };
   thread_battery_update_ = [this] {
-    struct inotify_event event = {0};
-    int nbytes = read(global_watch_fd_, &event, sizeof(event));
-    if (nbytes != sizeof(event) || event.mask & IN_IGNORED) {
-      thread_.stop();
-      return;
+    struct udev *udev;
+    struct udev_monitor *mon;
+    struct pollfd fds[1];
+    int fd;
+    udev = udev_new();
+    puts("Lets start udev shit!");
+    if (udev == NULL) {
+      fputs("Udev failed", stderr);
+        thread_.stop();
+        return;
+    }
+    mon = udev_monitor_new_from_netlink(udev, "kernel");
+    udev_monitor_filter_add_match_subsystem_devtype(mon, "power_supply", NULL);
+    udev_monitor_enable_receiving(mon);
+    fd = udev_monitor_get_fd(mon);
+    fds[0].fd = fd;
+    fds[0].events = POLLIN;
+    fds[0].revents = 0;
+    puts("Start listening");
+    if (poll(fds, 1, -1) > 0) {
+      puts("Got signal!");
+        struct udev_device *const dev = udev_monitor_receive_device(mon);
+        if (dev != NULL) {
+            puts(udev_device_get_sysname(dev));
+            udev_device_unref(dev);
+        }
+        else {
+            fputs("udev_monitor_receive_device() failed\n", stderr);
+            thread_.stop();
+            return;
+        }
     }
+    puts("Signaling ends");
+    udev_unref(udev);
     refreshBatteries();
     dp.emit();
   };