From 405f3d0aa3be30de6892bc9ea9303f0611ede5f6 Mon Sep 17 00:00:00 2001
From: Tim Schumacher <timschumi@gmx.de>
Date: Sat, 5 Jun 2021 02:23:53 +0200
Subject: [PATCH] LibC: Implement btowc()

---
 Userland/Libraries/LibC/wchar.cpp | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/Userland/Libraries/LibC/wchar.cpp b/Userland/Libraries/LibC/wchar.cpp
index 726d998bc9..b3bca30b3f 100644
--- a/Userland/Libraries/LibC/wchar.cpp
+++ b/Userland/Libraries/LibC/wchar.cpp
@@ -154,10 +154,18 @@ long long wcstoll(const wchar_t*, wchar_t**, int)
     TODO();
 }
 
-wint_t btowc(int)
+wint_t btowc(int c)
 {
-    dbgln("FIXME: Implement btowc()");
-    TODO();
+    if (c == EOF) {
+        return WEOF;
+    }
+
+    // Multi-byte sequences in UTF-8 have their highest bit set
+    if (c & (1 << 7)) {
+        return WEOF;
+    }
+
+    return c;
 }
 
 size_t mbrtowc(wchar_t*, const char*, size_t, mbstate_t*)