From 85a4a1822108d84c50d383211c4092a2aed7e7b4 Mon Sep 17 00:00:00 2001
From: Ryan Kes <alrayyes@gmail.com>
Date: Sun, 10 Mar 2019 21:12:49 +0100
Subject: [PATCH] Add linux support for backlight

---
 Makefile               |  1 +
 components/backlight.c | 36 ++++++++++++++++++++++++++++++++++++
 config.def.h           |  1 +
 slstatus.h             |  3 +++
 4 files changed, 41 insertions(+)
 create mode 100644 components/backlight.c

diff --git a/Makefile b/Makefile
index 20796b3..c93032f 100644
--- a/Makefile
+++ b/Makefile
@@ -6,6 +6,7 @@ include config.mk
 
 REQ = util
 COM =\
+	components/backlight\
 	components/battery\
 	components/cpu\
 	components/datetime\
diff --git a/components/backlight.c b/components/backlight.c
new file mode 100644
index 0000000..fcc062a
--- /dev/null
+++ b/components/backlight.c
@@ -0,0 +1,36 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdio.h>
+#include <string.h>
+
+#include "../util.h"
+
+#if defined(__linux__)
+	#include <limits.h>
+	#include <stdint.h>
+	#include <unistd.h>
+
+	const char *
+		backlight_perc(const char *backlight)
+		{
+			float value;
+			char path[PATH_MAX];
+
+			if (esnprintf(path, sizeof(path),
+				"/sys/class/backlight/%s/actual_brightness", backlight) < 0) {
+				return NULL;
+			}
+			if (pscanf(path, "%f", &value) != 1) {
+				return NULL;
+			}
+
+			return bprintf("%d", (int)(value / 852 * 100));
+		}
+
+#else
+	const char *
+		backlight_perc(const char *backlight)
+		{
+			return NULL;
+		}
+
+#endif
diff --git a/config.def.h b/config.def.h
index af289e5..d2f7045 100644
--- a/config.def.h
+++ b/config.def.h
@@ -12,6 +12,7 @@ static const char unknown_str[] = "n/a";
 /*
  * function            description                     argument (example)
  *
+ * backlight_perc      backlight percentage            backlight name (intel_backlight)
  * battery_perc        battery percentage              battery name (BAT0)
  *                                                     NULL on OpenBSD/FreeBSD
  * battery_state       battery charging state          battery name (BAT0)
diff --git a/slstatus.h b/slstatus.h
index 78aef21..a46f276 100644
--- a/slstatus.h
+++ b/slstatus.h
@@ -1,5 +1,8 @@
 /* See LICENSE file for copyright and license details. */
 
+/* backlight */
+const char *backlight_perc(const char *backlight);
+
 /* battery */
 const char *battery_perc(const char *);
 const char *battery_state(const char *);
-- 
2.21.0