From de3f907f25d6cdead6f8d1cf754398756c6fccc3 Mon Sep 17 00:00:00 2001
From: monkuous <84319635+monkuous@users.noreply.github.com>
Date: Sat, 15 Nov 2025 23:18:10 +0100
Subject: [PATCH] kernel: implement FIONREAD for ttys

---
 kernel-src/io/tty.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel-src/io/tty.c b/kernel-src/io/tty.c
index a13703df..1f283898 100644
--- a/kernel-src/io/tty.c
+++ b/kernel-src/io/tty.c
@@ -385,6 +385,13 @@ int tty_ioctl(tty_t *tty, unsigned long req, void *arg, int *result, cred_t *cre
 			size_t len = min(strlen(tty->name) + 1, TTY_NAME_MAX);
 			return USERCOPY_POSSIBLY_TO_USER(arg, tty->name, len);
 		}
+		case FIONREAD: {
+			MUTEX_ACQUIRE(&tty->readmutex);
+			int count = RINGBUFFER_DATACOUNT(&tty->readbuffer);
+			MUTEX_RELEASE(&tty->readmutex);
+			int status = USERCOPY_POSSIBLY_TO_USER(arg, &count, sizeof(count));
+			return status;
+		}
 		default:
 			return ENOTTY;
 	}