Fix led indicator getting turned off when turning caps lock/numlock on/off

include/LedIndicator.hpp

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <sys/types.h>
+#include <vector>
 #include <mglpp/system/Clock.hpp>
 
 namespace gsr {
@@ -17,11 +18,16 @@ namespace gsr {
     private:
         bool run_gsr_global_hotkeys_set_leds(bool enabled);
         void update_led(bool new_state);
+        void update_led_with_active_status();
+        void check_led_status_outdated();
     private:
         pid_t gsr_global_hotkeys_pid = -1;
         bool led_indicator_on = false;
         bool led_enabled = false;
         bool perform_blink = false;
         mgl::Clock blink_timer;
+
+        std::vector<int> led_brightness_files;
+        mgl::Clock read_led_brightness_timer;
     };
 }

src/LedIndicator.cpp

@@ -1,16 +1,64 @@
 #include "../include/LedIndicator.hpp"
 
 #include <unistd.h>
+#include <fcntl.h>
+#include <dirent.h>
 #include <sys/wait.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+
+// TODO: Support hotplug for led indicator check (led_brightness_files)
 
 namespace gsr {
+    static bool string_starts_with(const char *str, const char *sub) {
+        const int str_len = strlen(str);
+        const int sub_len = strlen(sub);
+        return str_len >= sub_len && memcmp(str, sub, sub_len) == 0;
+    }
+
+    static bool string_ends_with(const char *str, const char *sub) {
+        const int str_len = strlen(str);
+        const int sub_len = strlen(sub);
+        return str_len >= sub_len && memcmp(str + str_len - sub_len, sub, sub_len) == 0;
+    }
+
+    static std::vector<int> open_device_leds_brightness_files(const char *led_name_path) {
+        std::vector<int> files;
+
+        DIR *dir = opendir("/sys/class/leds");
+        if(!dir)
+            return files;
+
+        char brightness_filepath[1024];
+        struct dirent *entry;
+        while((entry = readdir(dir)) != NULL) {
+            if(entry->d_name[0] == '.')
+                continue;
+
+            if(!string_starts_with(entry->d_name, "input") || !string_ends_with(entry->d_name, led_name_path))
+                continue;
+
+            snprintf(brightness_filepath, sizeof(brightness_filepath), "/sys/class/leds/%s/brightness", entry->d_name);
+            const int led_brightness_file_fd = open(brightness_filepath, O_RDONLY | O_NONBLOCK);
+            if(led_brightness_file_fd > 0)
+                files.push_back(led_brightness_file_fd);
+        }
+
+        closedir(dir);
+        return files;
+    }
+
     LedIndicator::LedIndicator() {
+        led_brightness_files = open_device_leds_brightness_files("scrolllock");
         run_gsr_global_hotkeys_set_leds(false);
     }
 
     LedIndicator::~LedIndicator() {
+        for(int led_brightness_file_fd : led_brightness_files) {
+            close(led_brightness_file_fd);
+        }
+
         run_gsr_global_hotkeys_set_leds(false);
         if(gsr_global_hotkeys_pid > 0) {
             int status;
@@ -73,6 +121,11 @@ namespace gsr {
     }
 
     void LedIndicator::update() {
+        update_led_with_active_status();
+        check_led_status_outdated();
+    }
+
+    void LedIndicator::update_led_with_active_status() {
         if(perform_blink) {
             const double blink_elapsed_sec = blink_timer.get_elapsed_time_seconds();
             if(blink_elapsed_sec < 0.2) {
@@ -90,4 +143,28 @@ namespace gsr {
             update_led(led_enabled);
         }
     }
+
+    void LedIndicator::check_led_status_outdated() {
+        // The display server will unset our scroll lock led when pressing capslock/numlock as it updates
+        // all leds at the same time (not just the button pressed) (or at least xorg server does that).
+        // When that is done we want to set the scroll lock led on again if it should be on.
+        // TODO: Improve this. Dont do this with a timer.. but inotify doesn't work sysfs. netlink should work (man 7 netlink).
+        if(read_led_brightness_timer.get_elapsed_time_seconds() > 0.2) {
+            read_led_brightness_timer.restart();
+
+            bool led_status_outdated = false;
+            char buffer[32];
+            for(int led_brightness_file_fd : led_brightness_files) {
+                const ssize_t bytes_read = read(led_brightness_file_fd, buffer, sizeof(buffer));
+                if(bytes_read > 0) {
+                    if(buffer[0] == '0')
+                        led_status_outdated = true;
+                    lseek(led_brightness_file_fd, 0, SEEK_SET);
+                }
+            }
+
+            if(led_status_outdated && led_enabled)
+                run_gsr_global_hotkeys_set_leds(true);
+        }
+    }
 }