Improved argument handling

makefile

@@ -2,8 +2,8 @@
 all: rexbacklight
 
 rexbacklight: src/rexbacklight.c
-	gcc -std=c11 -O2 -Wall -Wextra -pedantic src/rexbacklight.c -o rexbacklight
-	strip --strip-all rexbacklight
+	gcc -std=c11 -g -Wall -Wextra -pedantic src/rexbacklight.c -o rexbacklight
+#	strip --strip-all rexbacklight
 
 .PHONY: install
 install:

src/rexbacklight.c

@@ -170,16 +170,122 @@ int process_arg(char* arg, float min, float current, float max){
 	return current;
 }
 
+#define OP_INC 1
+#define OP_DEC 2
+#define OP_SET 4
+#define OP_GET 128
+#define OP_NONE 0
+struct arg_values{
+	struct arg_values* next;
+
+	//Specific device to control
+	//NULL means all devices
+	const char* device;
+
+	//What value to put in the backlight file
+	int delta;
+
+	//How many seconds to transition
+	int fade_duration;
+
+	unsigned char operation;
+};
+
+void free_cmd_args(struct arg_values* a){
+	if(!a->next)
+		return;
+	free_cmd_args(a->next);
+	free(a->next);
+}
+
+struct arg_values process_cmd_args(int argc, char** argv){
+	struct arg_values ret = {0};
+	struct arg_values* curr = &ret;
+	//Skip argv[0]
+	for(int i = 1;i < argc;i++){
+		if(!strncmp(argv[i], "--", 2)){
+			if(!strcmp(argv[i] + 2, "get")){
+				curr->operation |= OP_GET;
+				continue;
+
+			}else if(!strcmp(argv[i] + 2, "fade")){
+				if(i == argc){
+					fprintf(stderr, "Missing argument to %s\n\n", argv[i]);
+					free_cmd_args(&ret);
+					usage(-5);
+				}
+				curr->fade_duration = strtol(argv[++i], NULL, 0);
+				continue;
+			}
+
+			else if(!strcmp(argv[i] + 2, "device")){
+				if(i == argc){
+					fprintf(stderr, "Missing argument to %s\n\n", argv[i]);
+					free_cmd_args(&ret);
+					usage(-5);
+				}
+				curr->next = calloc(1, sizeof(struct arg_values));
+				curr = curr->next;
+				curr->device = argv[++i];
+				continue;
+			}
+			else if(!strcmp(argv[i] + 2, "help")){
+				free_cmd_args(&ret);
+				usage(0);
+			}
+
+			else{
+				fprintf(stderr, "Unrecognized command line option '%s'\n\n", argv[i]);
+				free_cmd_args(&ret);
+				usage(-5);
+			}
+		}
+
+		else{
+			switch(argv[i][0]){
+				case '=':
+					curr->operation = OP_SET;
+					break;
+				case '-':
+					curr->operation = OP_DEC;
+					break;
+				case '+':
+					curr->operation = OP_INC;
+					break;
+				default:
+					fprintf(stderr, "Unrecognized command line option '%s'\n\n", argv[i]);
+					free_cmd_args(&ret);
+					usage(-5);
+			}
+			curr->delta = atof(&argv[i][1]);
+		}
+	}
+	if(!ret.operation){
+		if(!ret.next){
+			fprintf(stderr, "No operation requested!\n\n");
+			usage(-1);
+		}
+		for(curr = ret.next;curr;curr = curr->next){
+			if(!curr->operation){
+				fprintf(stderr, "No operation requested for device %s!\n\n", curr->device);
+				usage(-1);
+			}
+		}
+	}else{
+		for(curr = ret.next;curr;curr = curr->next){
+			if(!curr->operation)
+				curr->operation = ret.operation;
+		}
+	}
+	return ret;
+}
+
 //argv[1] shall be [+-=]<percentage>|min|max|off
 int main(int argc, char** argv){
 	const char* backlight_file = "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 || !strcmp(argv[1], "--help"))
-		usage(0);
-	else if(strlen(argv[1]) < 2)
-		usage(-1);
+	struct arg_values args = process_cmd_args(argc, argv);
 
 	//Acquire a list of backlight devices in sysfs
 	struct string_array backlight_names = get_backlight_sources();
@@ -215,7 +321,7 @@ int main(int argc, char** argv){
 		fclose(bright);
 	}
 	free_string_array(&backlight_names);
-
+	free_cmd_args(&args);
 	//Return to start directory
 	if(chdir(starting_dir)){
 		free(starting_dir);