From 9f685ac30a4bc2ec55e581b5779e4a9c7172f1d1 Mon Sep 17 00:00:00 2001
From: Brian Gianforcaro <b.gianfo@gmail.com>
Date: Fri, 7 Aug 2020 00:38:36 -0700
Subject: [PATCH] AK: Add static_ptr_cast support for the Userspace<T> pointer
 type

When using Userspace<T> there are certain syscalls where being able
to cast between types is needed. You should be able to easily cast
away the Userspace<T> wrapper, but it's perfectly safe to be able to
cast the internal type that is being wrapped.
---
 AK/Userspace.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/AK/Userspace.h b/AK/Userspace.h
index 4ac2ef07ed..8c8b778c13 100644
--- a/AK/Userspace.h
+++ b/AK/Userspace.h
@@ -73,6 +73,18 @@ private:
 #endif
 };
 
+template<typename T, typename U>
+inline Userspace<T> static_ptr_cast(const Userspace<U>& ptr)
+{
+#ifdef KERNEL
+    auto casted_ptr = static_cast<T>(ptr.unsafe_userspace_ptr());
+#else
+    auto casted_ptr = static_cast<T>(ptr.ptr());
+#endif
+    return Userspace<T>((FlatPtr)casted_ptr);
+}
+
 }
 
 using AK::Userspace;
+using AK::static_ptr_cast;