FileEvent.h

/*
 * Copyright (c) 2026, Pedigree Developers
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 */
 
#ifndef PEDIGREE_VFS_FILEEVENT_H
#define PEDIGREE_VFS_FILEEVENT_H
 
#include "pedigree/kernel/compiler.h"
#include "pedigree/kernel/processor/types.h"
#include "pedigree/kernel/utilities/SharedPointer.h"
#include "pedigree/kernel/utilities/StringView.h"
 
using FileEventMask = uint32_t;
 
namespace FileEvents {
enum Event : FileEventMask {
  None = 0,
  Access = 1U << 0,
  Modify = 1U << 1,
  Attributes = 1U << 2,
  CloseWrite = 1U << 3,
  CloseNoWrite = 1U << 4,
  Open = 1U << 5,
  Created = 1U << 6,
  Removed = 1U << 7,
  DeletedSelf = 1U << 8,
  SourceRetired = 1U << 9,
};
}  // namespace FileEvents
 
struct FileEvent {
  FileEvent(FileEventMask eventMask, const StringView& eventName, bool eventTargetIsDirectory,
            uint32_t producer = 0)
      : mask(eventMask),
        name(eventName),
        targetIsDirectory(eventTargetIsDirectory),
        producerPid(producer) {}
 
  FileEventMask mask;
  StringView name;
  bool targetIsDirectory;
  uint32_t producerPid;
};
 
class FileEventState;
class FileEventTarget;
 
class EXPORTED_PUBLIC FileEventObserver {
 public:
  virtual ~FileEventObserver() = default;
 
  virtual void fileEvent(const FileEvent& event) = 0;
};
 
class EXPORTED_PUBLIC FileEventSubscription {
 public:
  FileEventSubscription();
  FileEventSubscription(FileEventSubscription&& other) noexcept;
  ~FileEventSubscription();
 
  FileEventSubscription& operator=(FileEventSubscription&& other) noexcept;
 
  explicit operator bool() const;
  void reset();
 
 private:
  friend class FileEventSource;
 
  FileEventSubscription(const FileEventSubscription&) = delete;
  FileEventSubscription& operator=(const FileEventSubscription&) = delete;
 
  SharedPointer<FileEventState> m_State;
  SharedPointer<FileEventTarget> m_Target;
  SharedPointer<FileEventObserver> m_Observer;
};
 
class EXPORTED_PUBLIC FileEventSource {
 public:
  FileEventSource();
  virtual ~FileEventSource();
 
  MUST_USE_RESULT bool subscribeFileEvents(FileEventMask interest,
                                           const SharedPointer<FileEventObserver>& observer,
                                           FileEventSubscription& subscription);
 
 protected:
  static bool anyFileEventObservers();
  bool hasFileEventObservers(FileEventMask mask) const;
  void notifyFileEvent(const FileEvent& event);
  void notifyFinalFileEvent(const FileEvent& event);
  void beginFinalFileEvent(const FileEvent& event);
  void drainFileEvents();
  void closeFileEvents();
 
 private:
  FileEventSource(const FileEventSource&) = delete;
  FileEventSource& operator=(const FileEventSource&) = delete;
 
  SharedPointer<FileEventState> m_FileEventState;
};
 
class EXPORTED_PUBLIC InodeEventSource : public FileEventSource {
 public:
  void publish(const FileEvent& event);
  void beginRetirement();
  void finishRetirement();
};
 
#endif