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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_FILES_FILE_PATH_WATCHER_KQUEUE_H_
#define BASE_FILES_FILE_PATH_WATCHER_KQUEUE_H_
#include <sys/event.h>
#include <vector>
#include "base/files/file_path.h"
#include "base/files/file_path_watcher.h"
#include "base/message_loop/message_loop.h"
#include "base/single_thread_task_runner.h"
namespace base {
// 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/attibute 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 MessageLoopForIO::Watcher,
public MessageLoop::DestructionObserver {
public:
FilePathWatcherKQueue();
// MessageLoopForIO::Watcher overrides.
void OnFileCanReadWithoutBlocking(int fd) override;
void OnFileCanWriteWithoutBlocking(int fd) override;
// MessageLoop::DestructionObserver overrides.
void WillDestroyCurrentMessageLoop() override;
// FilePathWatcher::PlatformDelegate overrides.
bool Watch(const FilePath& path,
bool recursive,
const FilePathWatcher::Callback& callback) override;
void Cancel() override;
protected:
~FilePathWatcherKQueue() override;
private:
class EventData {
public:
EventData(const FilePath& path, const FilePath::StringType& subdir)
: path_(path), subdir_(subdir) { }
FilePath path_; // Full path to this item.
FilePath::StringType subdir_; // Path to any sub item.
};
typedef std::vector<struct kevent> EventVector;
// Can only be called on |io_task_runner_|'s thread.
void CancelOnMessageLoopThread() override;
// 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 int EventsForPath(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 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_;
scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
MessageLoopForIO::FileDescriptorWatcher kqueue_watcher_;
FilePathWatcher::Callback callback_;
FilePath target_;
int kqueue_;
DISALLOW_COPY_AND_ASSIGN(FilePathWatcherKQueue);
};
} // namespace base
#endif // BASE_FILES_FILE_PATH_WATCHER_KQUEUE_H_
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