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content / browser / file_system_access / file_path_watcher / file_path_watcher_kqueue.h [blame]
// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CONTENT_BROWSER_FILE_SYSTEM_ACCESS_FILE_PATH_WATCHER_FILE_PATH_WATCHER_KQUEUE_H_
#define CONTENT_BROWSER_FILE_SYSTEM_ACCESS_FILE_PATH_WATCHER_FILE_PATH_WATCHER_KQUEUE_H_
#include <sys/event.h>
#include <memory>
#include <vector>
#include "base/files/file_descriptor_watcher_posix.h"
#include "base/files/file_path.h"
#include "content/browser/file_system_access/file_path_watcher/file_path_watcher.h"
namespace content {
// Mac-specific file watcher implementation based on kqueue.
// The Linux and Windows versions are able to detect:
// - file creation/deletion/modification in a watched directory
// - file creation/deletion/modification for a watched file
// - modifications to the paths to a watched object that would affect the
// object such as renaming/attribute changes etc.
// The kqueue implementation will handle all of the items in the list above
// except for detecting modifications to files in a watched directory. It will
// detect the creation and deletion of files, just not the modification of
// files. It does however detect the attribute changes that the FSEvents impl
// would miss.
class FilePathWatcherKQueue : public FilePathWatcher::PlatformDelegate {
public:
FilePathWatcherKQueue();
FilePathWatcherKQueue(const FilePathWatcherKQueue&) = delete;
FilePathWatcherKQueue& operator=(const FilePathWatcherKQueue&) = delete;
~FilePathWatcherKQueue() override;
// FilePathWatcher::PlatformDelegate overrides.
bool Watch(const base::FilePath& path,
Type type,
const FilePathWatcher::Callback& callback) override;
void Cancel() override;
private:
class EventData {
public:
EventData(const base::FilePath& path,
const base::FilePath::StringType& subdir)
: path_(path), subdir_(subdir) {}
base::FilePath path_; // Full path to this item.
base::FilePath::StringType subdir_; // Path to any sub item.
};
typedef std::vector<struct kevent> EventVector;
// Called when data is available in |kqueue_|.
void OnKQueueReadable();
// Returns true if the kevent values are error free.
bool AreKeventValuesValid(struct kevent* kevents, int count);
// Respond to a change of attributes of the path component represented by
// |event|. Sets |target_file_affected| to true if |target_| is affected.
// Sets |update_watches| to true if |events_| need to be updated.
void HandleAttributesChange(const EventVector::iterator& event,
bool* target_file_affected,
bool* update_watches);
// Respond to a move or deletion of the path component represented by
// |event|. Sets |target_file_affected| to true if |target_| is affected.
// Sets |update_watches| to true if |events_| need to be updated.
void HandleDeleteOrMoveChange(const EventVector::iterator& event,
bool* target_file_affected,
bool* update_watches);
// Respond to a creation of an item in the path component represented by
// |event|. Sets |target_file_affected| to true if |target_| is affected.
// Sets |update_watches| to true if |events_| need to be updated.
void HandleCreateItemChange(const EventVector::iterator& event,
bool* target_file_affected,
bool* update_watches);
// Update |events_| with the current status of the system.
// Sets |target_file_affected| to true if |target_| is affected.
// Returns false if an error occurs.
bool UpdateWatches(bool* target_file_affected);
// Fills |events| with one kevent per component in |path|.
// Returns the number of valid events created where a valid event is
// defined as one that has a ident (file descriptor) field != -1.
static size_t EventsForPath(base::FilePath path, EventVector* events);
// Fills |events| with one kevent for |path|. Returns 1 if a file descriptor
// for |path| could be created, or 0 otherwise.
static size_t EventForItem(const base::FilePath& path, EventVector* events);
// Release a kevent generated by EventsForPath.
static void ReleaseEvent(struct kevent& event);
// Returns a file descriptor that will not block the system from deleting
// the file it references.
static uintptr_t FileDescriptorForPath(const base::FilePath& path);
static const uintptr_t kNoFileDescriptor = static_cast<uintptr_t>(-1);
// Closes |*fd| and sets |*fd| to -1.
static void CloseFileDescriptor(uintptr_t* fd);
// Returns true if kevent has open file descriptor.
static bool IsKeventFileDescriptorOpen(const struct kevent& event) {
return event.ident != kNoFileDescriptor;
}
static EventData* EventDataForKevent(const struct kevent& event) {
return reinterpret_cast<EventData*>(event.udata);
}
EventVector events_;
FilePathWatcher::Callback callback_;
base::FilePath target_;
int kqueue_;
// Throughout the lifetime of this, OnKQueueReadable() will be called when
// data is available in |kqueue_|.
std::unique_ptr<base::FileDescriptorWatcher::Controller>
kqueue_watch_controller_;
};
} // namespace content
#endif // CONTENT_BROWSER_FILE_SYSTEM_ACCESS_FILE_PATH_WATCHER_FILE_PATH_WATCHER_KQUEUE_H_