From 641083f3b89b7a7a5928b0eedb1a236949dcdc42 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Mon, 16 Aug 2021 20:58:23 +0200
Subject: [PATCH] Kernel: Customize File::unref() and make it virtual

Make File inherit from RefCountedBase and provide a custom unref()
implementation. This will allow subclasses that participate in lists to
remove themselves in a safe way when being destroyed.
---
 Kernel/FileSystem/File.cpp | 8 ++++++++
 Kernel/FileSystem/File.h   | 3 ++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/Kernel/FileSystem/File.cpp b/Kernel/FileSystem/File.cpp
index 0551f1a390..91311f639e 100644
--- a/Kernel/FileSystem/File.cpp
+++ b/Kernel/FileSystem/File.cpp
@@ -20,6 +20,14 @@ File::~File()
 {
 }
 
+bool File::unref() const
+{
+    if (deref_base())
+        return false;
+    delete this;
+    return true;
+}
+
 KResultOr<NonnullRefPtr<FileDescription>> File::open(int options)
 {
     auto description = FileDescription::create(*this);
diff --git a/Kernel/FileSystem/File.h b/Kernel/FileSystem/File.h
index cd29de6e5c..2914d4c088 100644
--- a/Kernel/FileSystem/File.h
+++ b/Kernel/FileSystem/File.h
@@ -71,9 +71,10 @@ public:
 //   - Should create a Region in the Process and return it if successful.
 
 class File
-    : public RefCounted<File>
+    : public RefCountedBase
     , public Weakable<File> {
 public:
+    virtual bool unref() const;
     virtual ~File();
 
     virtual KResultOr<NonnullRefPtr<FileDescription>> open(int options);