works kinda

Makefile

@@ -1,7 +1,7 @@
 .POSIX:
 
 CC = gcc 
-CFLAGS = -Wall -Werror -Wextra -pedantic -std=c11
+CFLAGS = -Wall -Werror -Wextra -pedantic -std=c11 -O2
 
 btor: btor.c
 	${CC} ${LDFLAGS} ${CFLAGS} btor.c -o btor

btor.c

@@ -38,7 +38,8 @@ int main(int argc, char **argv)
 		if ((st.st_mode & S_IFMT) != S_IFCHR)
 			continue;
 
-		int tmp_fd = openat(dirfd(dir), dp->d_name, O_RDWR | O_NONBLOCK);
+		// blocking io
+		int tmp_fd = openat(dirfd(dir), dp->d_name, O_RDWR);
 		if (tmp_fd < 0)
 			err(1, "openat:");
 		union {
@@ -47,12 +48,12 @@ int main(int argc, char **argv)
 		} vec;
 		if (ioctl(tmp_fd, EVIOCGBIT(0, EV_MAX), vec.b) < 0)
 			err(1, "ioctl:");
-		if (!test_bit(EV_KEY, vec.b))
+		if (!test_bit(EV_KEY, vec.b) || !test_bit(EV_ABS, vec.b))
 			continue;
 		if (ioctl(tmp_fd, EVIOCGBIT(EV_KEY, KEY_MAX), vec.k) < 0)
 			err(1, "ioctl:");
 
-		if (test_bit(BTN_STYLUS, vec.k) && test_bit(EV_ABS, vec.k)) {
+		if (test_bit(BTN_STYLUS, vec.k) && test_bit(BTN_TOOL_RUBBER, vec.k)) {
 			stylus = tmp_fd;
 			break;
 		}
@@ -65,28 +66,20 @@ int main(int argc, char **argv)
 	int poll_set = epoll_create(1);
 	if (poll_set < 0)
 		err(1, "epoll_create:");
-	struct epoll_event poll_ev = { .events = EPOLLIN | EPOLLOUT | EPOLLET };
+	struct epoll_event poll_ev = { .events = EPOLLIN };
 	if (epoll_ctl(poll_set, EPOLL_CTL_ADD, stylus, &poll_ev) < 0)
 		err(1, "epoll_ctl:");
 
-
-	unsigned char button_recived = 0;
 	struct input_event in_ev, out_ev;
 	while (epoll_wait(poll_set, &poll_ev, 1, -1) != -1) {
 		switch (poll_ev.events) {
 		case EPOLLIN:
 			if (read(stylus, &in_ev, sizeof(struct input_event)) < 0)
 				err(1, "read:");
-			if (in_ev.type != BTN_STYLUS)
-				break;
-			out_ev.type = BTN_TOOL_RUBBER;
-			out_ev.value = in_ev.value;
-			button_recived = 1;
-			break; 
-		case EPOLLOUT:
-			if (!button_recived)
+			if (in_ev.code != BTN_STYLUS)
 				break;
-			button_recived = 0;
+			out_ev = in_ev;
+			out_ev.code = BTN_TOOL_RUBBER;
 			if (write(stylus, &out_ev, sizeof(struct input_event)) < 0)
 				err(1, "write:");
 			break;