From dd26c2292ec7ca5385c99738f390ee7015451c4a Mon Sep 17 00:00:00 2001
From: clsr <clsr@clsr.net>
Date: Sun, 19 Jul 2020 22:31:12 +0200
Subject: Support leds and absolute paths in $BACKLIGHT, add --list

---
 bl | 92 +++++++++++++++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 62 insertions(+), 30 deletions(-)

diff --git a/bl b/bl
index 7db821e..c928519 100755
--- a/bl
+++ b/bl
@@ -12,33 +12,58 @@
 set -eu
 
 sys_backlight="/sys/class/backlight"
+sys_leds="/sys/class/leds"
+
+find_backlight() {
+	for f in "$sys_backlight"/*; do
+		if [ "$f" = "$sys_backlight/*" ]; then
+			printf "cannot find a backlight in %s\n" "$sys_backlight" >&2
+			exit 1
+		elif [ -n "$bldir" ]; then
+			printf "multiple backlights found, choose one with \$BACKLIGHT\n" >&2
+			exit 1
+		fi
+		bldir="$f"
+	done
+}
+
+is_backlight() {
+	[ -d "$1" ] && [ -f "$1/brightness" ] && [ -f "$1/max_brightness" ]
+}
+
+list_backlights() {
+	for f in "$sys_backlight"/* "$sys_leds"/*; do
+		if is_backlight "$f"; then
+			printf "%s\n" "${f##*/}"
+		fi
+	done
+}
 
 get_bldir() {
 	bldir=
-	if [ -n "${BACKLIGHT:-}" ]; then
-		bldir="$sys_backlight/$BACKLIGHT"
-	else
-		for f in "$sys_backlight"/*; do
-			if [ "$f" = "$sys_backlight/*" ]; then
-				printf "cannot find a backlight in %s\n" "$sys_backlight" >&2
-				exit 1
-			elif [ -n "$bldir" ]; then
-				printf "multiple backlights found, choose one with \$BACKLIGHT\n" >&2
+	case "${BACKLIGHT:-}" in
+		/*) bldir="$BACKLIGHT" ;;
+		"") find_backlight ;;
+		*)
+			if is_backlight "$sys_backlight/$BACKLIGHT"; then
+				bldir="$sys_backlight/$BACKLIGHT"
+			elif is_backlight "$sys_leds/$BACKLIGHT"; then
+				bldir="$sys_leds/$BACKLIGHT"
+			else
+				printf "no such backlight found: '%s'\n" "$BACKLIGHT" >&2
 				exit 1
 			fi
-			bldir="$f"
-			BACKLIGHT="${f##*/}"
-		done
-	fi
+			;;
+	esac
+	blname="${bldir##*/}"
 }
 
 read_num() {
-	read -r data <"$1"
-	if ! is_num "$data"; then
-		printf "expected a number reading '%s', but got '%s'\n" "$1" "$data" >&2
+	read -r num <"$1"
+	if ! is_num "$num"; then
+		printf "expected a number reading '%s', but got '%s'\n" "$1" "$num" >&2
 		exit 1
 	fi
-	printf %d "$data"
 }
 
 is_num() {
@@ -57,14 +82,16 @@ is_num() {
 }
 
 get_brightness() {
-	raw_max="$(read_num "$bldir/max_brightness")"
-	raw_curr="$(read_num "$bldir/brightness")"
+	read_num "$bldir/max_brightness"
+	raw_max="$num"
+	read_num "$bldir/brightness"
+	raw_curr="$num"
 	max=100
 	curr=$(( (raw_curr + (raw_max / 2 / max)) * max / raw_max ))
 
 	# brightness 0 tends to completely turn off the backlight
 	raw_min=1
-	case "$BACKLIGHT" in
+	case "$blname" in
 		nvidia_[0-9]*) raw_min=0 ;; # nvidia_0 at 0 is still not off
 	esac
 }
@@ -115,18 +142,19 @@ usage() {
 	printf "%s: usage: %s OPERATOR\n" "$prog" "$prog"
 	printf "\n"
 	printf "Operators:\n"
-	printf "  (none)     print current brightness in percentages\n"
-	printf "  PERC       set brightness to PERC percentages of max\n"
-	printf "  +PERC      increase brightness by PERC percentage points\n"
-	printf "  -PERC      decrease brightness by PERC percentage points\n"
-	printf "  =          print current brightness raw value\n"
-	printf "  VAL        set brightness to VAL raw value\n"
-	printf "  =+VAL      increase brightness by VAL raw value\n"
-	printf "  =-VAL      decrease brightness by VAL raw value\n"
+	printf "  (none)      print current brightness in percentages\n"
+	printf "  PERC        set brightness to PERC percentages of max\n"
+	printf "  +PERC       increase brightness by PERC percentage points\n"
+	printf "  -PERC       decrease brightness by PERC percentage points\n"
+	printf "  =           print current brightness raw value\n"
+	printf "  VAL         set brightness to VAL raw value\n"
+	printf "  =+VAL       increase brightness by VAL raw value\n"
+	printf "  =-VAL       decrease brightness by VAL raw value\n"
+	printf "  -L, --list  list all found backlights\n"
 	printf "\n"
 	printf "Environment variables:\n"
-	printf "  BACKLIGHT  the backlight in %s/ to use\n" "$sys_backlight"
-	printf "             (unnecessary if only one exists)\n"
+	printf "  BACKLIGHT   the backlight to use (absolute path or a folder\n"
+	printf "              in %s or %s)\n" "$sys_backlight" "$sys_leds"
 }
 
 main() {
@@ -138,6 +166,10 @@ main() {
 		usage
 		exit
 	fi
+	if [ "${1:-}" = "-L" ] || [ "${1:-}" = "--list" ]; then
+		list_backlights
+		exit
+	fi
 	get_bldir
 	get_brightness
 	op="${1:-}"
-- 
cgit