From 52ab139ca3a14c54c96e1a77b7b8003e64df7071 Mon Sep 17 00:00:00 2001
From: Raheman Vaiya <r.vaiya@gmail.com>
Date: Wed, 31 Aug 2022 21:14:41 -0400
Subject: [PATCH] monitor: Drain stdin on exit

---
 src/evloop.c  |  6 ++++--
 src/keyd.h    |  1 +
 src/monitor.c | 31 ++++++++++++++++++++-----------
 3 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/src/evloop.c b/src/evloop.c
index 2b59b4e..be28970 100644
--- a/src/evloop.c
+++ b/src/evloop.c
@@ -115,8 +115,10 @@ int evloop(int (*event_handler) (struct event *ev))
 		}
 
 		for (i = 0; i < nr_aux_fds; i++) {
-			if (pfds[i+ndevs+1].revents) {
-				ev.type = EV_FD_ACTIVITY;
+			short events = pfds[i+ndevs+1].revents;
+
+			if (events) {
+				ev.type = events & POLLERR ? EV_FD_ERR : EV_FD_ACTIVITY;
 				ev.fd = aux_fds[i];
 
 				timeout = event_handler(&ev);
diff --git a/src/keyd.h b/src/keyd.h
index cdad0f8..573d700 100644
--- a/src/keyd.h
+++ b/src/keyd.h
@@ -52,6 +52,7 @@ enum event_type {
 	EV_DEV_REMOVE,
 	EV_DEV_EVENT,
 	EV_FD_ACTIVITY,
+	EV_FD_ERR,
 	EV_TIMEOUT,
 };
 
diff --git a/src/monitor.c b/src/monitor.c
index 32e0045..d27815a 100644
--- a/src/monitor.c
+++ b/src/monitor.c
@@ -1,25 +1,31 @@
 #include "keyd.h"
 
-static void set_echo(int set)
+static void set_tflags(tcflag_t flags, int val)
 {
-	if (!isatty(1))
+	if (!isatty(0))
 		return;
 
 	struct termios tinfo;
 
-	tcgetattr(1, &tinfo);
+	tcgetattr(0, &tinfo);
 
-	if (set)
-		tinfo.c_lflag |= ECHO;
+	if (val)
+		tinfo.c_lflag |= flags;
 	else
-		tinfo.c_lflag &= ~ECHO;
+		tinfo.c_lflag &= ~flags;
 
-	tcsetattr(1, TCSANOW, &tinfo);
+	tcsetattr(0, TCSANOW, &tinfo);
 }
 
 static void cleanup()
 {
-	set_echo(1);
+	/* Drain STDIN (useful for scripting). */
+	set_tflags(ICANON, 0);
+	char buf[4096];
+	fcntl(0, F_SETFL, O_NONBLOCK);
+	while(read(0, buf, sizeof buf) > 0) {}
+
+	set_tflags(ICANON|ECHO, 1);
 }
 
 int event_handler(struct event *ev)
@@ -47,7 +53,7 @@ int event_handler(struct event *ev)
 			       ev->dev->product_id, name, ev->devev->pressed ? "down" : "up");
 	       }
 		break;
-	case EV_FD_ACTIVITY:
+	case EV_FD_ERR:
 		exit(0);
 		break;
 	default:
@@ -62,9 +68,12 @@ int event_handler(struct event *ev)
 
 int monitor(int argc, char *argv[])
 {
-	set_echo(0);
+	if (isatty(1))
+		set_tflags(ECHO, 0);
 
-	evloop_add_fd(1);
+	/* Eagerly terminate on pipe closures. */
+	if (!isatty(1))
+		evloop_add_fd(1);
 
 	setvbuf(stdout, NULL, _IOLBF, 0);
 	setvbuf(stderr, NULL, _IOLBF, 0);