126 lines
4.8 KiB
C++
126 lines
4.8 KiB
C++
// Copyright 2014 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_FILES_FILE_PATH_WATCHER_KQUEUE_H_
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#define BASE_FILES_FILE_PATH_WATCHER_KQUEUE_H_
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#include <sys/event.h>
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#include <memory>
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#include <vector>
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#include "base/files/file_descriptor_watcher_posix.h"
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#include "base/files/file_path.h"
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#include "base/files/file_path_watcher.h"
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#include "base/macros.h"
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namespace base {
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// Mac-specific file watcher implementation based on kqueue.
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// The Linux and Windows versions are able to detect:
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// - file creation/deletion/modification in a watched directory
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// - file creation/deletion/modification for a watched file
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// - modifications to the paths to a watched object that would affect the
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// object such as renaming/attibute changes etc.
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// The kqueue implementation will handle all of the items in the list above
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// except for detecting modifications to files in a watched directory. It will
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// detect the creation and deletion of files, just not the modification of
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// files. It does however detect the attribute changes that the FSEvents impl
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// would miss.
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class FilePathWatcherKQueue : public FilePathWatcher::PlatformDelegate {
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public:
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FilePathWatcherKQueue();
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~FilePathWatcherKQueue() override;
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// FilePathWatcher::PlatformDelegate overrides.
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bool Watch(const FilePath& path,
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bool recursive,
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const FilePathWatcher::Callback& callback) override;
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void Cancel() override;
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private:
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class EventData {
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public:
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EventData(const FilePath& path, const FilePath::StringType& subdir)
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: path_(path), subdir_(subdir) { }
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FilePath path_; // Full path to this item.
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FilePath::StringType subdir_; // Path to any sub item.
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};
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typedef std::vector<struct kevent> EventVector;
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// Called when data is available in |kqueue_|.
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void OnKQueueReadable();
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// Returns true if the kevent values are error free.
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bool AreKeventValuesValid(struct kevent* kevents, int count);
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// Respond to a change of attributes of the path component represented by
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// |event|. Sets |target_file_affected| to true if |target_| is affected.
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// Sets |update_watches| to true if |events_| need to be updated.
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void HandleAttributesChange(const EventVector::iterator& event,
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bool* target_file_affected,
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bool* update_watches);
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// Respond to a move or deletion of the path component represented by
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// |event|. Sets |target_file_affected| to true if |target_| is affected.
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// Sets |update_watches| to true if |events_| need to be updated.
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void HandleDeleteOrMoveChange(const EventVector::iterator& event,
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bool* target_file_affected,
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bool* update_watches);
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// Respond to a creation of an item in the path component represented by
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// |event|. Sets |target_file_affected| to true if |target_| is affected.
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// Sets |update_watches| to true if |events_| need to be updated.
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void HandleCreateItemChange(const EventVector::iterator& event,
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bool* target_file_affected,
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bool* update_watches);
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// Update |events_| with the current status of the system.
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// Sets |target_file_affected| to true if |target_| is affected.
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// Returns false if an error occurs.
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bool UpdateWatches(bool* target_file_affected);
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// Fills |events| with one kevent per component in |path|.
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// Returns the number of valid events created where a valid event is
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// defined as one that has a ident (file descriptor) field != -1.
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static int EventsForPath(FilePath path, EventVector *events);
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// Release a kevent generated by EventsForPath.
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static void ReleaseEvent(struct kevent& event);
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// Returns a file descriptor that will not block the system from deleting
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// the file it references.
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static uintptr_t FileDescriptorForPath(const FilePath& path);
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static const uintptr_t kNoFileDescriptor = static_cast<uintptr_t>(-1);
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// Closes |*fd| and sets |*fd| to -1.
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static void CloseFileDescriptor(uintptr_t* fd);
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// Returns true if kevent has open file descriptor.
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static bool IsKeventFileDescriptorOpen(const struct kevent& event) {
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return event.ident != kNoFileDescriptor;
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}
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static EventData* EventDataForKevent(const struct kevent& event) {
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return reinterpret_cast<EventData*>(event.udata);
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}
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EventVector events_;
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FilePathWatcher::Callback callback_;
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FilePath target_;
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int kqueue_;
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// Throughout the lifetime of this, OnKQueueReadable() will be called when
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// data is available in |kqueue_|.
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std::unique_ptr<FileDescriptorWatcher::Controller> kqueue_watch_controller_;
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DISALLOW_COPY_AND_ASSIGN(FilePathWatcherKQueue);
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};
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} // namespace base
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#endif // BASE_FILES_FILE_PATH_WATCHER_KQUEUE_H_
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