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08e927f084
Previously we were uncaching inodes from TmpFSInode::one_ref_left(). This was not safe, since one_ref_left() was effectively being called on a raw pointer after decrementing the local ref count and observing it become 1. There was a race here where someone else could trigger the destructor by unreffing to 0 before one_ref_left() got called, causing us to call one_ref_left() on a deleted inode. We fix this by using the new remove_from_secondary_lists() mechanism in ListedRefCounted and synchronizing all access to the TmpFS inode map with the main Inode::all_instances() lock. There's probably a nicer way to solve this.
94 lines
3.1 KiB
C++
94 lines
3.1 KiB
C++
/*
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* Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <Kernel/FileSystem/FileSystem.h>
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#include <Kernel/FileSystem/Inode.h>
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#include <Kernel/KBuffer.h>
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namespace Kernel {
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class TmpFSInode;
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class TmpFS final : public FileSystem {
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friend class TmpFSInode;
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public:
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virtual ~TmpFS() override;
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static ErrorOr<NonnullRefPtr<TmpFS>> try_create();
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virtual ErrorOr<void> initialize() override;
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virtual StringView class_name() const override { return "TmpFS"sv; }
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virtual bool supports_watchers() const override { return true; }
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virtual Inode& root_inode() override;
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private:
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TmpFS();
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RefPtr<TmpFSInode> m_root_inode;
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HashMap<InodeIndex, TmpFSInode*> m_inodes;
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ErrorOr<NonnullRefPtr<Inode>> get_inode(InodeIdentifier identifier) const;
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void register_inode(TmpFSInode&);
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void unregister_inode(InodeIdentifier);
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unsigned m_next_inode_index { 1 };
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unsigned next_inode_index();
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};
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class TmpFSInode final : public Inode {
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friend class TmpFS;
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public:
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virtual ~TmpFSInode() override;
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TmpFS& fs() { return static_cast<TmpFS&>(Inode::fs()); }
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const TmpFS& fs() const { return static_cast<const TmpFS&>(Inode::fs()); }
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// ^Inode
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virtual ErrorOr<size_t> read_bytes(off_t, size_t, UserOrKernelBuffer& buffer, OpenFileDescription*) const override;
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virtual InodeMetadata metadata() const override;
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virtual ErrorOr<void> traverse_as_directory(Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)>) const override;
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virtual ErrorOr<NonnullRefPtr<Inode>> lookup(StringView name) override;
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virtual ErrorOr<void> flush_metadata() override;
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virtual ErrorOr<size_t> write_bytes(off_t, size_t, const UserOrKernelBuffer& buffer, OpenFileDescription*) override;
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virtual ErrorOr<NonnullRefPtr<Inode>> create_child(StringView name, mode_t, dev_t, UserID, GroupID) override;
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virtual ErrorOr<void> add_child(Inode&, StringView name, mode_t) override;
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virtual ErrorOr<void> remove_child(StringView name) override;
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virtual ErrorOr<void> chmod(mode_t) override;
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virtual ErrorOr<void> chown(UserID, GroupID) override;
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virtual ErrorOr<void> truncate(u64) override;
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virtual ErrorOr<void> set_atime(time_t) override;
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virtual ErrorOr<void> set_ctime(time_t) override;
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virtual ErrorOr<void> set_mtime(time_t) override;
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virtual void remove_from_secondary_lists() override;
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private:
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TmpFSInode(TmpFS& fs, const InodeMetadata& metadata, InodeIdentifier parent);
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static ErrorOr<NonnullRefPtr<TmpFSInode>> try_create(TmpFS&, InodeMetadata const& metadata, InodeIdentifier parent);
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static ErrorOr<NonnullRefPtr<TmpFSInode>> try_create_root(TmpFS&);
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struct Child {
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NonnullOwnPtr<KString> name;
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NonnullRefPtr<TmpFSInode> inode;
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IntrusiveListNode<Child> list_node {};
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using List = IntrusiveList<&Child::list_node>;
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};
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Child* find_child_by_name(StringView);
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InodeMetadata m_metadata;
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InodeIdentifier m_parent;
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OwnPtr<KBuffer> m_content;
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Child::List m_children;
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};
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}
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