From 3dab9d0b5c2fc50648daf01fafe62a9173fe2a59 Mon Sep 17 00:00:00 2001
From: Jelle Raaijmakers <jelle@gmta.nl>
Date: Fri, 4 Jun 2021 20:32:19 +0200
Subject: [PATCH] Kernel: Implement offset for `lseek` with `SEEK_END`

---
 Kernel/FileSystem/FileDescription.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Kernel/FileSystem/FileDescription.cpp b/Kernel/FileSystem/FileDescription.cpp
index e80cf76275..30a3e5d81f 100644
--- a/Kernel/FileSystem/FileDescription.cpp
+++ b/Kernel/FileSystem/FileDescription.cpp
@@ -136,7 +136,9 @@ KResultOr<off_t> FileDescription::seek(off_t offset, int whence)
     case SEEK_END:
         if (!metadata().is_valid())
             return EIO;
-        new_offset = metadata().size;
+        if (Checked<off_t>::addition_would_overflow(metadata().size, offset))
+            return EOVERFLOW;
+        new_offset = metadata().size + offset;
         break;
     default:
         return EINVAL;