text: /*
   * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #pragma once
  
  #include <AK/Function.h>
  #include <AK/HashTable.h>
  #include <AK/InlineLinkedList.h>
  #include <AK/RefCounted.h>
  #include <AK/String.h>
  #include <AK/WeakPtr.h>
  #include <Kernel/FileSystem/FileSystem.h>
  #include <Kernel/FileSystem/InodeIdentifier.h>
  #include <Kernel/FileSystem/InodeMetadata.h>
  #include <Kernel/Forward.h>
  #include <Kernel/KResult.h>
  #include <Kernel/Lock.h>
  
  namespace Kernel {
  
  class Inode : public RefCounted<Inode>
      , public Weakable<Inode>
      , public InlineLinkedListNode<Inode> {
      friend class VFS;
      friend class FS;
  
  public:
      virtual ~Inode();
  
      virtual void one_ref_left() {}
  
      FS& fs() { return m_fs; }
      const FS& fs() const { return m_fs; }
      unsigned fsid() const;
      unsigned index() const { return m_index; }
  
      size_t size() const { return metadata().size; }
      bool is_symlink() const { return metadata().is_symlink(); }
      bool is_directory() const { return metadata().is_directory(); }
      bool is_character_device() const { return metadata().is_character_device(); }
      mode_t mode() const { return metadata().mode; }
  
      InodeIdentifier identifier() const { return { fsid(), index() }; }
      virtual InodeMetadata metadata() const = 0;
  
      ByteBuffer read_entire(FileDescription* = nullptr) const;
  
      virtual ssize_t read_bytes(off_t, ssize_t, u8* buffer, FileDescription*) const = 0;
      virtual bool traverse_as_directory(Function<bool(const FS::DirectoryEntry&)>) const = 0;
      virtual RefPtr<Inode> lookup(StringView name) = 0;
      virtual ssize_t write_bytes(off_t, ssize_t, const u8* data, FileDescription*) = 0;
      virtual KResult add_child(InodeIdentifier child_id, const StringView& name, mode_t) = 0;
      virtual KResult remove_child(const StringView& name) = 0;
      virtual size_t directory_entry_count() const = 0;
      virtual KResult chmod(mode_t) = 0;
      virtual KResult chown(uid_t, gid_t) = 0;
      virtual KResult truncate(u64) { return KSuccess; }
      virtual KResultOr<NonnullRefPtr<Custody>> resolve_as_link(Custody& base, RefPtr<Custody>* out_parent = nullptr, int options = 0, int symlink_recursion_level = 0) const;
  
      LocalSocket* socket() { return m_socket.ptr(); }
      const LocalSocket* socket() const { return m_socket.ptr(); }
      bool bind_socket(LocalSocket&);
      bool unbind_socket();
  
      virtual FileDescription* preopen_fd() { return nullptr; };
  
      bool is_metadata_dirty() const { return m_metadata_dirty; }
  
      virtual int set_atime(time_t);
      virtual int set_ctime(time_t);
      virtual int set_mtime(time_t);
      virtual KResult increment_link_count();
      virtual KResult decrement_link_count();
  
      virtual void flush_metadata() = 0;
  
      void will_be_destroyed();
  
      void set_shared_vmobject(SharedInodeVMObject&);
      SharedInodeVMObject* shared_vmobject() { return m_shared_vmobject.ptr(); }
      const SharedInodeVMObject* shared_vmobject() const { return m_shared_vmobject.ptr(); }
  
      static void sync();
  
      bool has_watchers() const { return !m_watchers.is_empty(); }
  
      void register_watcher(Badge<InodeWatcher>, InodeWatcher&);
      void unregister_watcher(Badge<InodeWatcher>, InodeWatcher&);
  
      // For InlineLinkedListNode.
      Inode* m_next { nullptr };
      Inode* m_prev { nullptr };
  
  protected:
      Inode(FS& fs, unsigned index);
      void set_metadata_dirty(bool);
      void inode_contents_changed(off_t, ssize_t, const u8*);
      void inode_size_changed(size_t old_size, size_t new_size);
      KResult prepare_to_write_data();
  
      mutable Lock m_lock { "Inode" };
  
  private:
      FS& m_fs;
      unsigned m_index { 0 };
      WeakPtr<SharedInodeVMObject> m_shared_vmobject;
      RefPtr<LocalSocket> m_socket;
      HashTable<InodeWatcher*> m_watchers;
      bool m_metadata_dirty { false };
  };
  
  }
  