--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/50-brightness.rules	Mon Sep 16 15:08:21 2019 +0200
@@ -0,0 +1,2 @@
+ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness"
+ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/INSTALL.md	Mon Sep 16 15:08:21 2019 +0200
@@ -0,0 +1,49 @@
+backlight INSTALL
+=================
+
+Supported systems
+-----------------
+
+- Linux: requires video ACPI module,
+- FreeBSD: requires the `acpi_video(4)` loaded.
+
+Installation on Linux
+---------------------
+
+First, build the program:
+
+	make
+
+On Linux, adjusting the brightness can be done as normal user if you have write
+access to the appropriate files which are usually under */sys*.
+
+The recommandation is to install the udev rule which change the ownership of the
+brightness file to `video` group and writable by users in this group. Use the
+`install-udev` for that purpose. Then don't forget to check if you are part of
+the video group.
+
+	make install
+	make install-udev
+
+Otherwise, as alternative you can simply install the binary as setuid if you
+don't run udev.
+
+	make install-setuid
+
+Installation on FreeBSD
+-----------------------
+
+In FreeBSD, it's required to have the tool in setuid as there is no way to
+change sysctl values from a regular user.
+
+Also, you will need the ACPI video module, add the following to your
+*/boot/loader.conf*:
+
+    acpi_video_load=YES
+
+Alternatively, you can compile this module into the kernel.
+
+Then install using:
+
+	make
+	make install-setuid

--- a/LICENSE.md	Thu Oct 18 12:50:02 2018 +0200
+++ b/LICENSE.md	Mon Sep 16 15:08:21 2019 +0200
@@ -1,7 +1,7 @@
 backlight LICENSE
 =================
 
-Copyright (c) 2010-2018 David Demelier <markand@malikania.fr>
+Copyright (c) 2010-2019 David Demelier <markand@malikania.fr>
 
 Permission to use, copy, modify, and/or distribute this software for any
 purpose with or without fee is hereby granted, provided that the above

--- a/Makefile	Thu Oct 18 12:50:02 2018 +0200
+++ b/Makefile	Mon Sep 16 15:08:21 2019 +0200
@@ -1,7 +1,7 @@
 #
 # Makefile for backlight
 #
-# Copyright (c) 2010-2018 David Demelier <markand@malikania.fr>
+# Copyright (c) 2010-2019 David Demelier <markand@malikania.fr>
 #
 # Permission to use, copy, modify, and distribute this software for any
 # purpose with or without fee is hereby granted, provided that the above
@@ -16,27 +16,41 @@
 # OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #
 
-PREFIX=		/usr/local/bin
+CC=             gcc
+CFLAGS=         -Wall -Wextra -ansi -pedantic -std=c99 -DNDEBUG ${EXTRA_CFLAGS}
+LDFLAGS=        ${EXTRA_LDFLAGS}
+LDLIBS=         ${EXTRA_LDLIBS}
 
-CC=		gcc
-CFLAGS=		-Wall -Wextra -ansi -pedantic -std=c99 -DNDEBUG
-
-ECHO=		echo
-RM=		rm -f
-INSTALL=	install -o root -g wheel -m 4755
+PREFIX=         /usr/local
+BINDIR=         ${PREFIX}/bin
+MANDIR=         ${PREFIX}/share/man
+LIBDIR=         ${PREFIX}/lib
 
-all: backlight
+PROG=           backlight
+SRCS=           backlight.c
+MAN1=           backlight.1
+OBJS=           ${SRCS:.c=.o}
 
-main.o: main.c
-	@echo CC $<
-	@${CC} ${CFLAGS} -c -o $@ $<
+all: ${PROG}
 
-backlight: main.o
-	@echo LD $@
-	@${CC} ${CFLAGS} -o $@ $<
+.c.o:
+	${CC} ${CFLAGS} -c -o $@ $<
+
+${PROG}: ${OBJS}
+	${CC} -o ${PROG} ${OBJS} ${LDFLAGS} ${LDLIBS}
 
 clean:
-	${RM} *.o backlight
+	rm -f ${OBJS} ${PROG}
+
+install: ${PROG}
+	install -dm0755 ${DESTDIR}${MANDIR}/man1
+	install -m0644 ${MAN1} ${DESTDIR}${MANDIR}/man1
 
-install: backlight
-	${INSTALL} $< ${PREFIX}
+install-udev:
+	install -Dm0755 ${PROG} ${DESTDIR}${BINDIR}/${PROG}
+	install -Dm0755 50-brightness.rules ${DESTDIR}${LIBDIR}/udev.d/rules.d/50-brightness.rules
+
+install-setuid: backlight
+	install -Dm4755 ${PROG} ${DESTDIR}${BINDIR}/${PROG}
+
+.PHONY: all clean install install-udev install-setuid

--- a/README.md	Thu Oct 18 12:50:02 2018 +0200
+++ b/README.md	Mon Sep 16 15:08:21 2019 +0200
@@ -6,29 +6,8 @@
 It has been designed for broken ACPI (e.g. HP) where fn-keys do not work,
 instead, you can map these keys to call this tool.
 
-Supported systems
-=================
-
-  - Linux, requires video ACPI module,
-  - FreeBSD, requires the acpi_video(4) loaded.
-
-Installation
-============
-
-It is recommended to install this tool using the setuid to allow non-root users
-to change the laptop backlight.
-
-    make
-    sudo make install
-
-For FreeBSD, add the following to your **/boot/loader.conf**:
-
-    acpi_video_load=YES
-
-Alternatively, you can compile this module into the kernel.
-
 Usage
-=====
+-----
 
 The backlight tool supports two commands, `up` and `down` which increment and
 decrement backlight respectively.
@@ -36,4 +15,4 @@
 Example:
 
     backlight up
-    backlight down
\ No newline at end of file
+    backlight down

--- a/main.c	Thu Oct 18 12:50:02 2018 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,237 +0,0 @@
-/*
- * main.c -- adjust laptop backlight using ACPI
- *
- * Copyright (c) 2010-2018 David Demelier <markand@malikania.fr>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-enum action {
-	Up,
-	Down
-};
-
-static void
-usage(const char *name)
-{
-	fprintf(stderr, "usage: %s down\n", name);
-	fprintf(stderr, "          %s up\n", name);
-	exit(1);
-}
-
-/* {{{ Support for FreeBSD */
-
-#if defined(__FreeBSD__)
-
-#include <sys/types.h>
-#include <sys/sysctl.h>
-
-static int
-set(enum action type)
-{
-	int current, next, i;
-	int msg[100];
-	size_t len, nextlen;
-
-	/* First, get all values availables */
-	len = sizeof (msg);
-
-	if (sysctlbyname("hw.acpi.video.lcd0.levels", msg, &len, NULL, 0) == -1) {
-		perror("sysctl");
-		return -1;
-	}
-
-	/* Get the current value */
-	len = sizeof (current);
-
-	if (sysctlbyname("hw.acpi.video.lcd0.brightness", &current, &len, NULL, 0) == -1) {
-		perror("sysctl");
-		return -1;
-	}
-
-	/* First find the index of 0 */
-	for (i = 0; msg[i] != 0; ++i)
-		continue;
-
-	/* Find the current value index in msg */
-	for (; msg[i] != current; ++i)
-		continue;
-
-	if (type == Up) {
-		if (msg[i] >= 100)
-			return msg[i];
-
-		next = msg[i + 1];
-	} else {
-		if (msg[i] == 0)
-			return (0);
-
-		next = msg[i - 1];
-	}
-
-	nextlen = sizeof (next);
-
-	if (sysctlbyname("hw.acpi.video.lcd0.brightness", &current, &len, &next, nextlen) == -1) {
-		perror("sysctl");
-		return -1;
-	}
-
-	return next;
-}
-
-#endif
-
-/* }}} */
-
-/* {{{ Support for Linux */
-
-#if defined(__linux__)
-
-#include <sys/types.h>
-#include <sys/stat.h>
-
-static int
-read_int(const char *path)
-{
-	FILE *fp;
-	int value;
-
-	if ((fp = fopen(path, "r")) == NULL) {
-		perror("abort: open");
-		return -1;
-	}
-
-	if (fscanf(fp, "%d", &value) != 1)
-		value = -1;
-	fclose(fp);
-
-	return value;
-}
-
-static int
-write_int(const char *path, int value)
-{
-	FILE *fp;
-
-	if ((fp = fopen(path, "w+")) == NULL) {
-		perror("open");
-		return -1;
-	}
-
-	fprintf(fp, "%d", value);
-
-	return value;
-}
-
-static const char *
-find_card(void)
-{
-	static const char *list[] = {
-		"/sys/class/backlight/acpi_video0",
-		"/sys/class/backlight/intel_backlight",
-		NULL
-	};
-
-	struct stat st;
-
-	for (const char **ptr = list; *ptr != NULL; ++ptr)
-		if (stat(*ptr, &st) >= 0)
-			return *ptr;
-
-	return NULL;
-}
-
-static int
-set(int type)
-{
-	int current, max;
-	const char *card = find_card();
-	char file[BUFSIZ];
-
-	/* Find a card adaptor */
-	if (!card) {
-		fprintf(stderr, "abort: could not find card adaptor\n");
-		return -1;
-	}
-
-	/* Read actual */
-	snprintf(file, sizeof (file), "%s/actual_brightness", card);
-	current = read_int(file);
-	if (current < 0)
-		return -1;
-
-	/* Read max */
-	snprintf(file, sizeof (file), "%s/max_brightness", card);
-	max = read_int(file);
-	if (max < 0)
-		return -1;
-
-	if (type == Up) {
-		current += max / 100;
-
-		if (current > max)
-			return max;
-	} else {
-		current -= max / 100;
-
-		if (current < 0)
-			return 0;
-	}
-
-	snprintf(file, sizeof (file), "%s/brightness", card);
-
-	return write_int(file, current);
-}
-
-#else
-
-/* Not supported */
-static int
-set(int type)
-{
-	(void)type;
-
-	fprintf(stderr, "abort: backlight is not supported on this system");
-	exit(1);
-}
-
-#endif
-
-/* }}} */
-
-int
-main(int argc, char *argv[])
-{
-	int st, type;
-
-	if (argc < 2)
-		usage(argv[0]);
-
-	if (strcmp(argv[1], "up") == 0)
-		type = Up;
-	else if (strcmp(argv[1], "down") == 0)
-		type = Down;
-	else
-		usage(argv[0]);
-
-	if ((st = set(type)) < 0)
-		return 1;
-
-	printf("switching to %d\n", st);
-
-	return 0;
-}