Add basic backlight percentage support

[slstatus.git] / components / backlight.c

diff --git a/components/backlight.c b/components/backlight.c
new file mode 100644 (file)
index 0000000..f9c4096
--- /dev/null
+++ b/components/backlight.c
@@ -0,0 +1,32 @@
+/* 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