Works with multiple backlights now

TODO

@@ -0,0 +1,3 @@
+Individual device control
+Query backlight percentage (get)
+allow fade in and fade out

brightness

@@ -0,0 +1 @@
+0

makefile

@@ -9,6 +9,8 @@ rexbacklight: rexbacklight.c
 install:
 	install -m4711 -o root -g root -s rexbacklight /usr/bin/rexbacklight
 
+.PHONY: uninstall
+	rm /usr/bin/rexbacklight
 .PHONY: clean
 clean:
 	rm rexbacklight

rexbacklight.c

@@ -21,8 +21,12 @@
 #include <unistd.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#include <dirent.h>
+#include <errno.h>
 
-void usage(void){
+static const char* backlight_dir = "/sys/class/backlight/";
+
+void usage(int exit_val){
 	fprintf(stderr, "Usage: rexbacklight [option]\n\n");
 
 	fprintf(stderr, "Options:\n");
@@ -33,13 +37,15 @@ void usage(void){
 	fprintf(stderr, "  max\n");
 	fprintf(stderr, "  min\n");
 
+	if(!exit_val){
 		fprintf(stderr, "\nrexbacklight Copyright (C) 2018 rexy712\n");
 		fprintf(stderr, "This program comes with ABSOLUTELY NO WARRANTY.\n");
 		fprintf(stderr, "This is free software, and you are welcome to redistribute it\n");
 		fprintf(stderr, "under certain conditions; see the GNU GPLv3 for details.\n");
 		fprintf(stderr, "A copy of the GPLv3 is available with the source in the file 'LICENSE'\n");
+	}
 
-	exit(-1);
+	exit(exit_val);
 }
 
 int check_valid_files(const char* f1, const char* f2){
@@ -63,6 +69,47 @@ int check_valid_files(const char* f1, const char* f2){
 	return 0;
 }
 
+struct string_array{
+	char** list;
+	int size;
+};
+
+//Get a list of backlight devices in sysfs
+struct string_array get_backlight_sources(void){
+
+	DIR* fd;
+	struct dirent* dir;
+
+	fd = opendir(backlight_dir);
+	if(!fd){
+		fprintf(stderr, "Unable to open '%s' for reading!\n", backlight_dir);
+		return (struct string_array){.list = NULL, .size = 0};
+	}
+
+	char** list = malloc(sizeof(const char*) * 8);
+	int i;
+
+	for(i = 0;(dir = readdir(fd));){
+		if(!strcmp(dir->d_name, ".") || !strcmp(dir->d_name, "..")){
+			continue;
+		}
+		list[i] = malloc(strlen(dir->d_name) + 1);
+		strcpy(list[i], dir->d_name);
+		i++;
+	}
+
+	closedir(fd);
+
+	return (struct string_array){.list = list, .size = i};
+}
+
+
+void free_string_array(struct string_array* s){
+	for(int i = 0;i < s->size;i++)
+		free(s->list[i]);
+	free(s->list);
+}
+
 int get_brightness(const char* file){
 	FILE* bright = fopen(file, "r");
 	char buff[127];
@@ -79,89 +126,119 @@ int get_brightness(const char* file){
 	return atof(buff);
 }
 
+int process_arg(char* arg, float min, float current, float max){
+	//Amount to inc/dec
+	int delta = delta = max * atof(arg + 1) / 100.0;
+
+	//Increment
+	if(arg[0] == '+'){
+		delta = delta + current;
+		if(delta >= max)
+			return max;
+		else{
+			return delta;
+		}
+
+	//Decrement
+	}else if(arg[0] == '-'){
+		delta = current - delta;
+		if(delta <= min)
+			return min;
+		else
+			return delta;
+
+	//Directly set
+	}else if(arg[0] == '='){
+		if(delta >= max)
+			return max;
+		else if(delta <= min)
+			return min;
+		else
+			return delta;
+
+	//Set to minimum plus one (so backlight is actually on!)
+	}else if(!strcmp("min", arg)){
+		return min + 1;
+
+	//Turn off backlight
+	}else if(!strcmp("off", arg)){
+		return min;
+
+	//Set to maximum
+	}else if(!strcmp("max", arg)){
+		return max;
+	//Unknown option
+	}else{
+		usage(-1);
+	}
+	return current;
+}
+
 //argv[1] shall be [+-=]<percentage>|min|max|off
 int main(int argc, char** argv){
-	const char* backlight_file     = "/sys/class/backlight/intel_backlight/brightness";
+	const char* backlight_file = "brightness";
-	const char* max_backlight_file = "/sys/class/backlight/intel_backlight/max_brightness";
+	const char* max_backlight_file = "max_brightness";
 
 	//Make sure we have an argument and it is at least 2 characters long
-	if(argc < 2 || strlen(argv[1]) < 2)
+	if(argc < 2 || !strcmp(argv[1], "--help"))
-		usage();
+		usage(0);
-	else if(!strcmp(argv[1], "--help"))
+	else if(strlen(argv[1]) < 2)
-		usage();
+		usage(-1);
 
+	//Gain access to sysfs files
 	if(setuid(0)){
 		fprintf(stderr, "Unable to setuid to 0!\n");
 		return -3;
 	}
 
+	//Make sure we aren't in a chroot environment (prevents writing to a file we don't want to!)
 	if(check_valid_files("/", "/proc/1/root")){
 		fprintf(stderr, "No chroot today\n");
 		return -4;
 	}
 
-	//Min brightness is just 0, so set it up front
+	//Now that we've verified we're in a safe environment to do the work,
-	float min_brightness = 0;
+	//Let's get everything set up!
-	float max_brightness = get_brightness(max_backlight_file);
-	float current_brightness = get_brightness(backlight_file);
 
-	//Amount to inc/dec
+	//Acquire a list of backlight devices in sysfs
-	int delta;
+	struct string_array backlight_names = get_backlight_sources();
-	if(strlen(argv[1]) > 0)
+	if(backlight_names.size == 0){
-		delta = max_brightness * atof(argv[1] + 1) / 100.0;
+		fprintf(stderr, "No backlights devices found!\n");
-	else
+		return -1;
-		delta = 0;
+	}
+
+	//save our starting directory so we can change to each backlight directory
+	const char* starting_dir = getcwd(NULL, 0);
+
+	if(chdir(backlight_dir)){
+		fprintf(stderr, "Unable to read backlight sysfs directory!\n");
+		return -2;
+	}
+
+	//Set all backlight sources to the requested percentage
+	for(int i = 0;i < backlight_names.size;i++){
+		if(chdir(backlight_names.list[i])){
+			fprintf(stderr, "Unable to open backlight directory \"%s%s\"!\n", backlight_dir, backlight_names.list[i]);
+			continue;
+		}
 
 		//Open brightness file for writing
+		int out = process_arg(argv[1], 0, get_brightness(backlight_file), get_brightness(max_backlight_file));
 		FILE* bright = fopen(backlight_file, "w+");
 		if(!bright){
 			fprintf(stderr, "Unable to open brightness file \"%s\" for writing!\n", backlight_file);
-		return 1;
+			continue;
 		}
+		fprintf(bright, "%d", out);
 
-	//Increment
-	if(argv[1][0] == '+'){
-		delta = delta + current_brightness;
-		if(delta >= max_brightness)
-			fprintf(bright, "%d", (int)max_brightness);
-		else{
-			fprintf(bright, "%d", delta);
-		}
-
-	//Decrement
-	}else if(argv[1][0] == '-'){
-		delta = current_brightness - delta;
-		if(delta <= min_brightness)
-			fprintf(bright, "%d", (int)min_brightness);
-		else
-			fprintf(bright, "%d", delta);
-
-	//Directly set
-	}else if(argv[1][0] == '='){
-		if(delta >= max_brightness)
-			fprintf(bright, "%d", (int)max_brightness);
-		else if(delta <= min_brightness)
-			fprintf(bright, "%d", (int)min_brightness);
-		else
-			fprintf(bright, "%d", delta);
-
-	//Set to minimum plus one (so backlight is actually on!)
-	}else if(!strcmp("min", argv[1])){
-		fprintf(bright, "%d", (int)(min_brightness + 1));
-
-	//Turn off backlight
-	}else if(!strcmp("off", argv[1])){
-		fprintf(bright, "%d", (int)min_brightness);
-
-	//Set to maximum
-	}else if(!strcmp("max", argv[1])){
-		fprintf(bright, "%d", (int)max_brightness);
-
-	//Unknown option
-	}else{
 		fclose(bright);
-		usage();
 	}
-	fclose(bright);
+	free_string_array(&backlight_names);
+	if(chdir(starting_dir)){
+		fprintf(stderr, "Could not return to starting directory!\nWas the directory moved/deleted?\n");
+		if(chdir(getenv("HOME")) || chdir("/")){
+			return -5;
+		}
+	}
 	return 0;
 }