Support keyboard led indicator on wayland as well

tools/gsr-global-hotkeys/leds.c

@@ -0,0 +1,139 @@
+#include "leds.h"
+
+/* C stdlib */
+#include <string.h>
+#include <stdio.h>
+#include <limits.h>
+#include <stddef.h>
+
+/* POSIX */
+#include <fcntl.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <errno.h>
+
+/* LINUX */
+#include <linux/input.h>
+
+static int get_max_brightness(const char *sys_class_path, const char *filename) {
+    char path[PATH_MAX];
+    snprintf(path, sizeof(path), "%s/%s/max_brightness", sys_class_path, filename);
+
+    const int fd = open(path, O_RDONLY);
+    if(fd == -1) {
+        fprintf(stderr, "Warning: get_max_brightness open error: %s\n", strerror(errno));
+        return false;
+    }
+
+    bool success = false;
+    int max_brightness = 0;
+    char buffer[32];
+    const ssize_t num_bytes_read = read(fd, buffer, sizeof(buffer));
+    if(num_bytes_read > 0) {
+        buffer[num_bytes_read] = '\0';
+        success = sscanf(buffer, "%d", &max_brightness) == 1;
+    }
+
+    close(fd);
+    return success;
+}
+
+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 int sys_class_led_path_get_event_number(const char *sys_class_path, const char *filename) {
+    char path[PATH_MAX];
+    snprintf(path, sizeof(path), "%s/%s/device", sys_class_path, filename);
+
+    DIR *dir = opendir(path);
+    if(!dir)
+        return -1;
+
+    int event_number = -1;
+    struct dirent *entry;
+    while((entry = readdir(dir)) != NULL) {
+        int v = -1;
+        if(sscanf(entry->d_name, "event%d", &v) == 1 && v >= 0) {
+            event_number = v;
+            break;
+        }
+    }
+
+    closedir(dir);
+    return event_number;
+}
+
+/*
+    We have to do this retardation instead of setting /sys/class/leds brightness since it doesn't work with /dev/uinput
+    and we cant loop all /dev/input devices and open and write to them either since closing a /dev/input is very slow on linux.
+    So we instead check which devices have the led before opening it.
+*/
+static bool set_device_leds(const char *led_name_path, bool enabled) {
+    DIR *dir = opendir("/sys/class/leds");
+    if(!dir)
+        return false;
+
+    char dev_input_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;
+
+        const int event_number = sys_class_led_path_get_event_number("/sys/class/leds", entry->d_name);
+        if(event_number == -1)
+            continue;
+
+        snprintf(dev_input_filepath, sizeof(dev_input_filepath), "/dev/input/event%d", event_number);
+        
+        const int device_fd = open(dev_input_filepath, O_WRONLY);
+        if(device_fd == -1)
+            continue;
+
+        int brightness = 0;
+        if(enabled) {
+            brightness = get_max_brightness("/sys/class/leds", entry->d_name);
+            if(brightness < 0)
+                brightness = 1;
+        }
+
+        struct input_event led_data = {
+            .type = EV_LED,
+            .code = LED_SCROLLL,
+            .value = brightness
+        };
+        write(device_fd, &led_data, sizeof(led_data));
+
+        struct input_event syn_data = {
+            .type = EV_SYN,
+            .code = 0,
+            .value = 0
+        };
+        write(device_fd, &syn_data, sizeof(syn_data));
+
+        close(device_fd);
+    }
+
+    closedir(dir);
+    return true;
+}
+
+bool set_leds(const char *led_name, bool enabled) {
+    if(strcmp(led_name, "Scroll Lock") == 0) {
+        return set_device_leds("::scrolllock", enabled);
+    } else {
+        fprintf(stderr, "Error: invalid led: \"%s\", expected \"Scroll Lock\"\n", led_name);
+        return false;
+    }
+}