+/* See LICENSE file for copyright and license details. */
+#include "../util.h"
+
+#if defined(__linux__)
+ #include <limits.h>
+
+ #define BRIGHTNESS_MAX "/sys/class/backlight/%s/max_brightness"
+ #define BRIGHTNESS_CUR "/sys/class/backlight/%s/brightness"
+
+ const char *
+ backlight_perc(const char *card)
+ {
+ char path[PATH_MAX];
+ int max, cur;
+
+ if (esnprintf(path, sizeof (path), BRIGHTNESS_MAX, card) < 0 ||
+ pscanf(path, "%d", &max) != 1) {
+ return NULL;
+ }
+
+ if (esnprintf(path, sizeof (path), BRIGHTNESS_CUR, card) < 0 ||
+ pscanf(path, "%d", &cur) != 1) {
+ return NULL;
+ }
+
+ if (max == 0) {
+ return NULL;
+ }
+
+ return bprintf("%d", cur * 100 / max);
+ }
+#endif