1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_FILES_FILE_PATH_WATCHER_KQUEUE_H_ 6 #define BASE_FILES_FILE_PATH_WATCHER_KQUEUE_H_ 7 8 #include <sys/event.h> 9 #include <vector> 10 11 #include "base/files/file_path.h" 12 #include "base/files/file_path_watcher.h" 13 #include "base/macros.h" 14 #include "base/message_loop/message_loop.h" 15 #include "base/single_thread_task_runner.h" 16 17 namespace base { 18 19 // Mac-specific file watcher implementation based on kqueue. 20 // The Linux and Windows versions are able to detect: 21 // - file creation/deletion/modification in a watched directory 22 // - file creation/deletion/modification for a watched file 23 // - modifications to the paths to a watched object that would affect the 24 // object such as renaming/attibute changes etc. 25 // The kqueue implementation will handle all of the items in the list above 26 // except for detecting modifications to files in a watched directory. It will 27 // detect the creation and deletion of files, just not the modification of 28 // files. It does however detect the attribute changes that the FSEvents impl 29 // would miss. 30 class FilePathWatcherKQueue : public FilePathWatcher::PlatformDelegate, 31 public MessageLoopForIO::Watcher, 32 public MessageLoop::DestructionObserver { 33 public: 34 FilePathWatcherKQueue(); 35 36 // MessageLoopForIO::Watcher overrides. 37 void OnFileCanReadWithoutBlocking(int fd) override; 38 void OnFileCanWriteWithoutBlocking(int fd) override; 39 40 // MessageLoop::DestructionObserver overrides. 41 void WillDestroyCurrentMessageLoop() override; 42 43 // FilePathWatcher::PlatformDelegate overrides. 44 bool Watch(const FilePath& path, 45 bool recursive, 46 const FilePathWatcher::Callback& callback) override; 47 void Cancel() override; 48 49 protected: 50 ~FilePathWatcherKQueue() override; 51 52 private: 53 class EventData { 54 public: EventData(const FilePath & path,const FilePath::StringType & subdir)55 EventData(const FilePath& path, const FilePath::StringType& subdir) 56 : path_(path), subdir_(subdir) { } 57 FilePath path_; // Full path to this item. 58 FilePath::StringType subdir_; // Path to any sub item. 59 }; 60 61 typedef std::vector<struct kevent> EventVector; 62 63 // Can only be called on |io_task_runner_|'s thread. 64 void CancelOnMessageLoopThread() override; 65 66 // Returns true if the kevent values are error free. 67 bool AreKeventValuesValid(struct kevent* kevents, int count); 68 69 // Respond to a change of attributes of the path component represented by 70 // |event|. Sets |target_file_affected| to true if |target_| is affected. 71 // Sets |update_watches| to true if |events_| need to be updated. 72 void HandleAttributesChange(const EventVector::iterator& event, 73 bool* target_file_affected, 74 bool* update_watches); 75 76 // Respond to a move or deletion of the path component represented by 77 // |event|. Sets |target_file_affected| to true if |target_| is affected. 78 // Sets |update_watches| to true if |events_| need to be updated. 79 void HandleDeleteOrMoveChange(const EventVector::iterator& event, 80 bool* target_file_affected, 81 bool* update_watches); 82 83 // Respond to a creation of an item in the path component represented by 84 // |event|. Sets |target_file_affected| to true if |target_| is affected. 85 // Sets |update_watches| to true if |events_| need to be updated. 86 void HandleCreateItemChange(const EventVector::iterator& event, 87 bool* target_file_affected, 88 bool* update_watches); 89 90 // Update |events_| with the current status of the system. 91 // Sets |target_file_affected| to true if |target_| is affected. 92 // Returns false if an error occurs. 93 bool UpdateWatches(bool* target_file_affected); 94 95 // Fills |events| with one kevent per component in |path|. 96 // Returns the number of valid events created where a valid event is 97 // defined as one that has a ident (file descriptor) field != -1. 98 static int EventsForPath(FilePath path, EventVector *events); 99 100 // Release a kevent generated by EventsForPath. 101 static void ReleaseEvent(struct kevent& event); 102 103 // Returns a file descriptor that will not block the system from deleting 104 // the file it references. 105 static uintptr_t FileDescriptorForPath(const FilePath& path); 106 107 static const uintptr_t kNoFileDescriptor = static_cast<uintptr_t>(-1); 108 109 // Closes |*fd| and sets |*fd| to -1. 110 static void CloseFileDescriptor(uintptr_t* fd); 111 112 // Returns true if kevent has open file descriptor. IsKeventFileDescriptorOpen(const struct kevent & event)113 static bool IsKeventFileDescriptorOpen(const struct kevent& event) { 114 return event.ident != kNoFileDescriptor; 115 } 116 EventDataForKevent(const struct kevent & event)117 static EventData* EventDataForKevent(const struct kevent& event) { 118 return reinterpret_cast<EventData*>(event.udata); 119 } 120 121 EventVector events_; 122 scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_; 123 MessageLoopForIO::FileDescriptorWatcher kqueue_watcher_; 124 FilePathWatcher::Callback callback_; 125 FilePath target_; 126 int kqueue_; 127 128 DISALLOW_COPY_AND_ASSIGN(FilePathWatcherKQueue); 129 }; 130 131 } // namespace base 132 133 #endif // BASE_FILES_FILE_PATH_WATCHER_KQUEUE_H_ 134