From 6a555af1f19d2e7a8a76963056ddba6a0cbb253e Mon Sep 17 00:00:00 2001
From: Liav A <liavalb@gmail.com>
Date: Sun, 4 Dec 2022 10:27:19 +0200
Subject: [PATCH] Kernel: Add callback on ".." directory entry for a TmpFS root
 directory

---
 Kernel/FileSystem/TmpFS/FileSystem.h |  4 +++-
 Kernel/FileSystem/TmpFS/Inode.cpp    | 25 +++++++++++++++++--------
 Kernel/FileSystem/TmpFS/Inode.h      |  3 +++
 3 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/Kernel/FileSystem/TmpFS/FileSystem.h b/Kernel/FileSystem/TmpFS/FileSystem.h
index 13c0fbbb759..29901480952 100644
--- a/Kernel/FileSystem/TmpFS/FileSystem.h
+++ b/Kernel/FileSystem/TmpFS/FileSystem.h
@@ -32,7 +32,9 @@ private:
 
     LockRefPtr<TmpFSInode> m_root_inode;
 
-    unsigned m_next_inode_index { 1 };
+    // NOTE: We start by assigning InodeIndex of 2, because 0 is invalid and 1
+    // is reserved for the root directory inode.
+    unsigned m_next_inode_index { 2 };
     unsigned next_inode_index();
 };
 
diff --git a/Kernel/FileSystem/TmpFS/Inode.cpp b/Kernel/FileSystem/TmpFS/Inode.cpp
index da51cf8b715..60c07e8bac2 100644
--- a/Kernel/FileSystem/TmpFS/Inode.cpp
+++ b/Kernel/FileSystem/TmpFS/Inode.cpp
@@ -18,6 +18,18 @@ TmpFSInode::TmpFSInode(TmpFS& fs, InodeMetadata const& metadata, LockWeakPtr<Tmp
     m_metadata.inode = identifier();
 }
 
+TmpFSInode::TmpFSInode(TmpFS& fs)
+    : Inode(fs, 1)
+    , m_root_directory_inode(true)
+{
+    auto now = kgettimeofday();
+    m_metadata.inode = identifier();
+    m_metadata.atime = now;
+    m_metadata.ctime = now;
+    m_metadata.mtime = now;
+    m_metadata.mode = S_IFDIR | S_ISVTX | 0777;
+}
+
 TmpFSInode::~TmpFSInode() = default;
 
 ErrorOr<NonnullLockRefPtr<TmpFSInode>> TmpFSInode::try_create(TmpFS& fs, InodeMetadata const& metadata, LockWeakPtr<TmpFSInode> parent)
@@ -27,13 +39,7 @@ ErrorOr<NonnullLockRefPtr<TmpFSInode>> TmpFSInode::try_create(TmpFS& fs, InodeMe
 
 ErrorOr<NonnullLockRefPtr<TmpFSInode>> TmpFSInode::try_create_root(TmpFS& fs)
 {
-    InodeMetadata metadata;
-    auto now = kgettimeofday();
-    metadata.atime = now;
-    metadata.ctime = now;
-    metadata.mtime = now;
-    metadata.mode = S_IFDIR | S_ISVTX | 0777;
-    return try_create(fs, metadata, {});
+    return adopt_nonnull_lock_ref_or_enomem(new (nothrow) TmpFSInode(fs));
 }
 
 InodeMetadata TmpFSInode::metadata() const
@@ -51,8 +57,11 @@ ErrorOr<void> TmpFSInode::traverse_as_directory(Function<ErrorOr<void>(FileSyste
         return ENOTDIR;
 
     TRY(callback({ "."sv, identifier(), 0 }));
-    if (auto parent = m_parent.strong_ref())
+    if (m_root_directory_inode) {
+        TRY(callback({ ".."sv, identifier(), 0 }));
+    } else if (auto parent = m_parent.strong_ref()) {
         TRY(callback({ ".."sv, parent->identifier(), 0 }));
+    }
 
     for (auto& child : m_children) {
         TRY(callback({ child.name->view(), child.inode->identifier(), 0 }));
diff --git a/Kernel/FileSystem/TmpFS/Inode.h b/Kernel/FileSystem/TmpFS/Inode.h
index 5f9c472833f..84af878f773 100644
--- a/Kernel/FileSystem/TmpFS/Inode.h
+++ b/Kernel/FileSystem/TmpFS/Inode.h
@@ -38,6 +38,7 @@ public:
 
 private:
     TmpFSInode(TmpFS& fs, InodeMetadata const& metadata, LockWeakPtr<TmpFSInode> parent);
+    explicit TmpFSInode(TmpFS& fs);
     static ErrorOr<NonnullLockRefPtr<TmpFSInode>> try_create(TmpFS&, InodeMetadata const& metadata, LockWeakPtr<TmpFSInode> parent);
     static ErrorOr<NonnullLockRefPtr<TmpFSInode>> try_create_root(TmpFS&);
 
@@ -84,6 +85,8 @@ private:
         NonnullLockRefPtr<Memory::AnonymousVMObject> m_content_buffer_vmobject;
     };
 
+    bool const m_root_directory_inode { false };
+
     DataBlock::List m_blocks;
     Child::List m_children;
 };