Preprocessor is cool

src/rexbacklight.c

@@ -24,6 +24,23 @@
 #include <dirent.h>
 #include <errno.h>
 
+#define OP_INC 1
+#define OP_DEC 2
+#define OP_SET 4
+#define OP_GET 128
+#define OP_NONE 0
+
+#define GET_LONG_OPT "--get"
+#define GET_SHORT_OPT "-g"
+#define FADE_LONG_OPT "--fade"
+#define FADE_SHORT_OPT "-f"
+#define DEVICE_LONG_OPT "--device"
+#define DEVICE_SHORT_OPT "-d"
+#define HELP_LONG_OPT "--help"
+#define HELP_SHORT_OPT "-h"
+
+#define CHECK_OPTION(opt, arg) (!strcmp(opt##_LONG_OPT, arg) || !strcmp(opt##_SHORT_OPT, arg))
+
 //This is where backlight devices can be found in sysfs
 static const char* backlight_dir = "/sys/class/backlight/";
 
@@ -170,11 +187,6 @@ 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;
 
@@ -198,49 +210,57 @@ void free_cmd_args(struct arg_values* a){
 	free(a->next);
 }
 
+#define CHECK_NEXT_ARG(rval) \
+	do{ \
+		if(i == argc - 1){ \
+			fprintf(stderr, "Missing argument to '%s'\n\n", argv[i]); \
+			free_cmd_args(&ret); \
+			usage(rval); \
+		} \
+	}while(0)
+#define UNRECOGNIZED_OPTION(rval) \
+	do{ \
+		fprintf(stderr, "Unrecognized command line option '%s'\n\n", argv[i]); \
+		free_cmd_args(&ret); \
+		usage(rval); \
+	}while(0);
+
 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")){
+		//Check for switches
-				if(i == argc){
+		if(CHECK_OPTION(GET, argv[i])){
-					fprintf(stderr, "Missing argument to %s\n\n", argv[i]);
+			curr->operation |= OP_GET;
-					free_cmd_args(&ret);
+			continue;
-					usage(-5);
-				}
-				curr->fade_duration = strtol(argv[++i], NULL, 0);
-				continue;
-			}
 
-			else if(!strcmp(argv[i] + 2, "device")){
+		}else if(CHECK_OPTION(FADE, argv[i])){
-				if(i == argc){
+			CHECK_NEXT_ARG(-5);
-					fprintf(stderr, "Missing argument to %s\n\n", argv[i]);
+			curr->fade_duration = strtol(argv[++i], NULL, 0);
-					free_cmd_args(&ret);
+			continue;
-					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 if(CHECK_OPTION(DEVICE, argv[i])){
+			CHECK_NEXT_ARG(-5);
+			curr->next = calloc(1, sizeof(struct arg_values));
+			curr = curr->next;
+			curr->device = argv[++i];
+			continue;
+		}
+		else if(CHECK_OPTION(HELP, argv[i])){
+			free_cmd_args(&ret);
+			usage(0);
+		}
+
+		//If we get a '-' followed by not a number, it's not a known option
+		else if(argv[i][1] < '0' || argv[i][1] > '9'){
+			UNRECOGNIZED_OPTION(-4);
+		}
+
+		//If we get a '-' followed by a number, it's a decrement request
 		else{
 			switch(argv[i][0]){
 				case '=':
@@ -253,24 +273,26 @@ struct arg_values process_cmd_args(int argc, char** argv){
 					curr->operation = OP_INC;
 					break;
 				default:
-					fprintf(stderr, "Unrecognized command line option '%s'\n\n", argv[i]);
+					UNRECOGNIZED_OPTION(-4);
-					free_cmd_args(&ret);
-					usage(-5);
 			}
 			curr->delta = atof(&argv[i][1]);
 		}
 	}
+
+	//If there isn't an operation defined in the global context and there is no specified device, there's nothing to do
 	if(!ret.operation){
 		if(!ret.next){
 			fprintf(stderr, "No operation requested!\n\n");
 			usage(-1);
 		}
+		//if there is a device specified, make sure each one has a requested operation
 		for(curr = ret.next;curr;curr = curr->next){
 			if(!curr->operation){
-				fprintf(stderr, "No operation requested for device %s!\n\n", curr->device);
+				fprintf(stderr, "No operation requested for device '%s'!\n\n", curr->device);
 				usage(-1);
 			}
 		}
+	//If there is a globally defined operation, apply it to the devices with no operation request
 	}else{
 		for(curr = ret.next;curr;curr = curr->next){
 			if(!curr->operation)
@@ -279,6 +301,8 @@ struct arg_values process_cmd_args(int argc, char** argv){
 	}
 	return ret;
 }
+#undef CHECK_OPTION
+#undef UNRECOGNIZED_OPTION
 
 //argv[1] shall be [+-=]<percentage>|min|max|off
 int main(int argc, char** argv){