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https://github.com/RGBCube/serenity
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df66c28479
These APIs were clearly modeled after Ext2FS internals, and make perfect sense
in Ext2FS context. The new APIs are more generic, and map better to the
semantics exported to the userspace, where inode identifiers only appear in
stat() and readdir() output, but never in any input.
This will also hopefully reduce the potential for races (see commit c44b4d61f3).
Lastly, this makes it way more viable to implement a filesystem that only
synthesizes its inodes lazily when queried, and destroys them when they are no
longer in use. With inode identifiers being used to reference inodes, the only
choice for such a filesystem is to persist any inode it has given out the
identifier for, because it might be queried at any later time. With direct
references to inodes, the filesystem will know when the last reference is
dropped and the inode can be safely destroyed.
113 lines
4.1 KiB
C++
113 lines
4.1 KiB
C++
/*
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* Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/HashMap.h>
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#include <AK/Optional.h>
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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 FS {
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friend class TmpFSInode;
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public:
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virtual ~TmpFS() override;
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static NonnullRefPtr<TmpFS> create();
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virtual bool initialize() override;
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virtual const char* class_name() const override { return "TmpFS"; }
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virtual bool supports_watchers() const override { return true; }
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virtual NonnullRefPtr<Inode> root_inode() const override;
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virtual RefPtr<Inode> get_inode(InodeIdentifier) const 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<unsigned, NonnullRefPtr<TmpFSInode>> m_inodes;
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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 ssize_t read_bytes(off_t, ssize_t, u8* buffer, FileDescription*) const override;
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virtual InodeMetadata metadata() const override;
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virtual KResult traverse_as_directory(Function<bool(const FS::DirectoryEntry&)>) const override;
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virtual RefPtr<Inode> lookup(StringView name) override;
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virtual void flush_metadata() override;
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virtual ssize_t write_bytes(off_t, ssize_t, const u8* buffer, FileDescription*) override;
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virtual KResultOr<NonnullRefPtr<Inode>> create_child(const String& name, mode_t, dev_t, uid_t, gid_t) override;
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virtual KResult add_child(Inode&, const StringView& name, mode_t) override;
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virtual KResult remove_child(const StringView& name) override;
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virtual size_t directory_entry_count() const override;
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virtual KResult chmod(mode_t) override;
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virtual KResult chown(uid_t, gid_t) override;
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virtual KResult truncate(u64) override;
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virtual int set_atime(time_t) override;
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virtual int set_ctime(time_t) override;
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virtual int set_mtime(time_t) override;
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virtual void one_ref_left() override;
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private:
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TmpFSInode(TmpFS& fs, InodeMetadata metadata, InodeIdentifier parent);
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static NonnullRefPtr<TmpFSInode> create(TmpFS&, InodeMetadata metadata, InodeIdentifier parent);
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static NonnullRefPtr<TmpFSInode> create_root(TmpFS&);
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void notify_watchers();
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InodeMetadata m_metadata;
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InodeIdentifier m_parent;
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Optional<KBuffer> m_content;
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struct Child {
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FS::DirectoryEntry entry;
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NonnullRefPtr<TmpFSInode> inode;
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};
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HashMap<String, Child> m_children;
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};
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}
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