From 938bbf51ebc257d61f20efac9b7a76c6db286c45 Mon Sep 17 00:00:00 2001
From: "K. Lange" <klange@toaruos.org>
Date: Thu, 2 Nov 2023 16:59:57 +0900
Subject: [PATCH] tty: implement FLUSH on tcsetattr correctly?

---
 base/usr/include/kernel/ringbuffer.h | 1 +
 kernel/misc/ringbuffer.c             | 6 ++++++
 kernel/vfs/tty.c                     | 7 ++++++-
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/base/usr/include/kernel/ringbuffer.h b/base/usr/include/kernel/ringbuffer.h
index 95eaef91..2151c388 100644
--- a/base/usr/include/kernel/ringbuffer.h
+++ b/base/usr/include/kernel/ringbuffer.h
@@ -31,4 +31,5 @@ void ring_buffer_interrupt(ring_buffer_t * ring_buffer);
 void ring_buffer_alert_waiters(ring_buffer_t * ring_buffer);
 void ring_buffer_select_wait(ring_buffer_t * ring_buffer, void * process);
 void ring_buffer_eof(ring_buffer_t * ring_buffer);
+void ring_buffer_discard(ring_buffer_t * ring_buffer);
 
diff --git a/kernel/misc/ringbuffer.c b/kernel/misc/ringbuffer.c
index 3cc05733..25c7c0c5 100644
--- a/kernel/misc/ringbuffer.c
+++ b/kernel/misc/ringbuffer.c
@@ -86,6 +86,12 @@ void ring_buffer_select_wait(ring_buffer_t * ring_buffer, void * process) {
 	list_insert(((process_t *)process)->node_waits, ring_buffer);
 }
 
+void ring_buffer_discard(ring_buffer_t * ring_buffer) {
+	spin_lock(ring_buffer->lock);
+	ring_buffer->read_ptr = ring_buffer->write_ptr;
+	spin_unlock(ring_buffer->lock);
+}
+
 size_t ring_buffer_read(ring_buffer_t * ring_buffer, size_t size, uint8_t * buffer) {
 	size_t collected = 0;
 	while (collected == 0) {
diff --git a/kernel/vfs/tty.c b/kernel/vfs/tty.c
index 5ecff71a..706d3aee 100644
--- a/kernel/vfs/tty.c
+++ b/kernel/vfs/tty.c
@@ -322,13 +322,18 @@ int pty_ioctl(pty_t * pty, unsigned long request, void * argp) {
 			return 0;
 		case TCSETS:
 		case TCSETSW:
-		case TCSETSF:
 			if (!argp) return -EINVAL;
 			validate(argp);
+			/* TODO wait on output for SETSW */
 			if (!(((struct termios *)argp)->c_lflag & ICANON) && (pty->tios.c_lflag & ICANON)) {
 				/* Switch out of canonical mode, the dump the input buffer */
 				dump_input_buffer(pty);
 			}
+			goto tcset_common;
+		case TCSETSF:
+			clear_input_buffer(pty);
+			ring_buffer_discard(pty->in);
+		tcset_common:
 			memcpy(&pty->tios, argp, sizeof(struct termios));
 			return 0;
 		default: