From 8aff315c7b07cd0e6b3fc9b380af87abcd859418 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Wed, 2 Jul 2025 00:55:04 +0300
Subject: [PATCH] LibC: fflush file in setvbuf before updating the buffer

---
 userspace/libraries/LibC/stdio.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/userspace/libraries/LibC/stdio.cpp b/userspace/libraries/LibC/stdio.cpp
index 43709a13..567f745e 100644
--- a/userspace/libraries/LibC/stdio.cpp
+++ b/userspace/libraries/LibC/stdio.cpp
@@ -908,12 +908,16 @@ void setbuf(FILE* file, char* buffer)
 
 int setvbuf(FILE* file, char* buffer, int type, size_t size)
 {
+	ScopeLock _(file);
+
 	if (file->fd == -1)
 	{
 		errno = EBADF;
 		return -1;
 	}
 
+	(void)fflush(file);
+
 	if (size == 0)
 		type = _IONBF;