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