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| 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 #include "base/files/file_path_watcher_fsevents.h" | |
| 6 | |
| 7 #include <list> | |
| 8 | |
| 9 #include "base/bind.h" | |
| 10 #include "base/files/file_util.h" | |
| 11 #include "base/lazy_instance.h" | |
| 12 #include "base/logging.h" | |
| 13 #include "base/mac/libdispatch_task_runner.h" | |
| 14 #include "base/mac/scoped_cftyperef.h" | |
| 15 #include "base/message_loop/message_loop.h" | |
| 16 #include "base/thread_task_runner_handle.h" | |
| 17 | |
| 18 namespace base { | |
| 19 | |
| 20 namespace { | |
| 21 | |
| 22 // The latency parameter passed to FSEventsStreamCreate(). | |
| 23 const CFAbsoluteTime kEventLatencySeconds = 0.3; | |
| 24 | |
| 25 class FSEventsTaskRunner : public mac::LibDispatchTaskRunner { | |
| 26 public: | |
| 27 FSEventsTaskRunner() | |
| 28 : mac::LibDispatchTaskRunner("org.chromium.FilePathWatcherFSEvents") { | |
| 29 } | |
| 30 | |
| 31 protected: | |
| 32 ~FSEventsTaskRunner() override {} | |
| 33 }; | |
| 34 | |
| 35 static LazyInstance<FSEventsTaskRunner>::Leaky g_task_runner = | |
| 36 LAZY_INSTANCE_INITIALIZER; | |
| 37 | |
| 38 // Resolve any symlinks in the path. | |
| 39 FilePath ResolvePath(const FilePath& path) { | |
| 40 const unsigned kMaxLinksToResolve = 255; | |
| 41 | |
| 42 std::vector<FilePath::StringType> component_vector; | |
| 43 path.GetComponents(&component_vector); | |
| 44 std::list<FilePath::StringType> | |
| 45 components(component_vector.begin(), component_vector.end()); | |
| 46 | |
| 47 FilePath result; | |
| 48 unsigned resolve_count = 0; | |
| 49 while (resolve_count < kMaxLinksToResolve && !components.empty()) { | |
| 50 FilePath component(*components.begin()); | |
| 51 components.pop_front(); | |
| 52 | |
| 53 FilePath current; | |
| 54 if (component.IsAbsolute()) { | |
| 55 current = component; | |
| 56 } else { | |
| 57 current = result.Append(component); | |
| 58 } | |
| 59 | |
| 60 FilePath target; | |
| 61 if (ReadSymbolicLink(current, &target)) { | |
| 62 if (target.IsAbsolute()) | |
| 63 result.clear(); | |
| 64 std::vector<FilePath::StringType> target_components; | |
| 65 target.GetComponents(&target_components); | |
| 66 components.insert(components.begin(), target_components.begin(), | |
| 67 target_components.end()); | |
| 68 resolve_count++; | |
| 69 } else { | |
| 70 result = current; | |
| 71 } | |
| 72 } | |
| 73 | |
| 74 if (resolve_count >= kMaxLinksToResolve) | |
| 75 result.clear(); | |
| 76 return result; | |
| 77 } | |
| 78 | |
| 79 } // namespace | |
| 80 | |
| 81 FilePathWatcherFSEvents::FilePathWatcherFSEvents() : fsevent_stream_(NULL) { | |
| 82 } | |
| 83 | |
| 84 bool FilePathWatcherFSEvents::Watch(const FilePath& path, | |
| 85 bool recursive, | |
| 86 const FilePathWatcher::Callback& callback) { | |
| 87 DCHECK(MessageLoopForIO::current()); | |
| 88 DCHECK(!callback.is_null()); | |
| 89 DCHECK(callback_.is_null()); | |
| 90 | |
| 91 // This class could support non-recursive watches, but that is currently | |
| 92 // left to FilePathWatcherKQueue. | |
| 93 if (!recursive) | |
| 94 return false; | |
| 95 | |
| 96 set_task_runner(ThreadTaskRunnerHandle::Get()); | |
| 97 callback_ = callback; | |
| 98 | |
| 99 FSEventStreamEventId start_event = FSEventsGetCurrentEventId(); | |
| 100 g_task_runner.Get().PostTask( | |
| 101 FROM_HERE, Bind(&FilePathWatcherFSEvents::StartEventStream, this, | |
| 102 start_event, path)); | |
| 103 return true; | |
| 104 } | |
| 105 | |
| 106 void FilePathWatcherFSEvents::Cancel() { | |
| 107 set_cancelled(); | |
| 108 callback_.Reset(); | |
| 109 | |
| 110 // Switch to the dispatch queue thread to tear down the event stream. | |
| 111 g_task_runner.Get().PostTask( | |
| 112 FROM_HERE, | |
| 113 Bind(&FilePathWatcherFSEvents::CancelOnMessageLoopThread, this)); | |
| 114 } | |
| 115 | |
| 116 // static | |
| 117 void FilePathWatcherFSEvents::FSEventsCallback( | |
| 118 ConstFSEventStreamRef stream, | |
| 119 void* event_watcher, | |
| 120 size_t num_events, | |
| 121 void* event_paths, | |
| 122 const FSEventStreamEventFlags flags[], | |
| 123 const FSEventStreamEventId event_ids[]) { | |
| 124 FilePathWatcherFSEvents* watcher = | |
| 125 reinterpret_cast<FilePathWatcherFSEvents*>(event_watcher); | |
| 126 DCHECK(g_task_runner.Get().RunsTasksOnCurrentThread()); | |
| 127 | |
| 128 bool root_changed = watcher->ResolveTargetPath(); | |
| 129 std::vector<FilePath> paths; | |
| 130 FSEventStreamEventId root_change_at = FSEventStreamGetLatestEventId(stream); | |
| 131 for (size_t i = 0; i < num_events; i++) { | |
| 132 if (flags[i] & kFSEventStreamEventFlagRootChanged) | |
| 133 root_changed = true; | |
| 134 if (event_ids[i]) | |
| 135 root_change_at = std::min(root_change_at, event_ids[i]); | |
| 136 paths.push_back(FilePath( | |
| 137 reinterpret_cast<char**>(event_paths)[i]).StripTrailingSeparators()); | |
| 138 } | |
| 139 | |
| 140 // Reinitialize the event stream if we find changes to the root. This is | |
| 141 // necessary since FSEvents doesn't report any events for the subtree after | |
| 142 // the directory to be watched gets created. | |
| 143 if (root_changed) { | |
| 144 // Resetting the event stream from within the callback fails (FSEvents spews | |
| 145 // bad file descriptor errors), so post a task to do the reset. | |
| 146 g_task_runner.Get().PostTask( | |
| 147 FROM_HERE, | |
| 148 Bind(&FilePathWatcherFSEvents::UpdateEventStream, watcher, | |
| 149 root_change_at)); | |
| 150 } | |
| 151 | |
| 152 watcher->OnFilePathsChanged(paths); | |
| 153 } | |
| 154 | |
| 155 FilePathWatcherFSEvents::~FilePathWatcherFSEvents() { | |
| 156 // This method may be called on either the libdispatch or task_runner() | |
| 157 // thread. Checking callback_ on the libdispatch thread here is safe because | |
| 158 // it is executing in a task posted by Cancel() which first reset callback_. | |
| 159 // PostTask forms a sufficient memory barrier to ensure that the value is | |
| 160 // consistent on the target thread. | |
| 161 DCHECK(callback_.is_null()) | |
| 162 << "Cancel() must be called before FilePathWatcher is destroyed."; | |
| 163 } | |
| 164 | |
| 165 void FilePathWatcherFSEvents::OnFilePathsChanged( | |
| 166 const std::vector<FilePath>& paths) { | |
| 167 DCHECK(g_task_runner.Get().RunsTasksOnCurrentThread()); | |
| 168 DCHECK(!resolved_target_.empty()); | |
| 169 task_runner()->PostTask( | |
| 170 FROM_HERE, Bind(&FilePathWatcherFSEvents::DispatchEvents, this, paths, | |
| 171 target_, resolved_target_)); | |
| 172 } | |
| 173 | |
| 174 void FilePathWatcherFSEvents::DispatchEvents(const std::vector<FilePath>& paths, | |
| 175 const FilePath& target, | |
| 176 const FilePath& resolved_target) { | |
| 177 DCHECK(task_runner()->RunsTasksOnCurrentThread()); | |
| 178 | |
| 179 // Don't issue callbacks after Cancel() has been called. | |
| 180 if (is_cancelled() || callback_.is_null()) { | |
| 181 return; | |
| 182 } | |
| 183 | |
| 184 for (const FilePath& path : paths) { | |
| 185 if (resolved_target.IsParent(path) || resolved_target == path) { | |
| 186 callback_.Run(target, false); | |
| 187 return; | |
| 188 } | |
| 189 } | |
| 190 } | |
| 191 | |
| 192 void FilePathWatcherFSEvents::CancelOnMessageLoopThread() { | |
| 193 // For all other implementations, the "message loop thread" is the IO thread, | |
| 194 // as returned by task_runner(). This implementation, however, needs to | |
| 195 // cancel pending work on the Dispatch Queue thread. | |
| 196 DCHECK(g_task_runner.Get().RunsTasksOnCurrentThread()); | |
| 197 | |
| 198 if (fsevent_stream_) { | |
| 199 DestroyEventStream(); | |
| 200 target_.clear(); | |
| 201 resolved_target_.clear(); | |
| 202 } | |
| 203 } | |
| 204 | |
| 205 void FilePathWatcherFSEvents::UpdateEventStream( | |
| 206 FSEventStreamEventId start_event) { | |
| 207 DCHECK(g_task_runner.Get().RunsTasksOnCurrentThread()); | |
| 208 | |
| 209 // It can happen that the watcher gets canceled while tasks that call this | |
| 210 // function are still in flight, so abort if this situation is detected. | |
| 211 if (resolved_target_.empty()) | |
| 212 return; | |
| 213 | |
| 214 if (fsevent_stream_) | |
| 215 DestroyEventStream(); | |
| 216 | |
| 217 ScopedCFTypeRef<CFStringRef> cf_path(CFStringCreateWithCString( | |
| 218 NULL, resolved_target_.value().c_str(), kCFStringEncodingMacHFS)); | |
| 219 ScopedCFTypeRef<CFStringRef> cf_dir_path(CFStringCreateWithCString( | |
| 220 NULL, resolved_target_.DirName().value().c_str(), | |
| 221 kCFStringEncodingMacHFS)); | |
| 222 CFStringRef paths_array[] = { cf_path.get(), cf_dir_path.get() }; | |
| 223 ScopedCFTypeRef<CFArrayRef> watched_paths(CFArrayCreate( | |
| 224 NULL, reinterpret_cast<const void**>(paths_array), arraysize(paths_array), | |
| 225 &kCFTypeArrayCallBacks)); | |
| 226 | |
| 227 FSEventStreamContext context; | |
| 228 context.version = 0; | |
| 229 context.info = this; | |
| 230 context.retain = NULL; | |
| 231 context.release = NULL; | |
| 232 context.copyDescription = NULL; | |
| 233 | |
| 234 fsevent_stream_ = FSEventStreamCreate(NULL, &FSEventsCallback, &context, | |
| 235 watched_paths, | |
| 236 start_event, | |
| 237 kEventLatencySeconds, | |
| 238 kFSEventStreamCreateFlagWatchRoot); | |
| 239 FSEventStreamSetDispatchQueue(fsevent_stream_, | |
| 240 g_task_runner.Get().GetDispatchQueue()); | |
| 241 | |
| 242 if (!FSEventStreamStart(fsevent_stream_)) { | |
| 243 task_runner()->PostTask( | |
| 244 FROM_HERE, Bind(&FilePathWatcherFSEvents::ReportError, this, target_)); | |
| 245 } | |
| 246 } | |
| 247 | |
| 248 bool FilePathWatcherFSEvents::ResolveTargetPath() { | |
| 249 DCHECK(g_task_runner.Get().RunsTasksOnCurrentThread()); | |
| 250 FilePath resolved = ResolvePath(target_).StripTrailingSeparators(); | |
| 251 bool changed = resolved != resolved_target_; | |
| 252 resolved_target_ = resolved; | |
| 253 if (resolved_target_.empty()) { | |
| 254 task_runner()->PostTask( | |
| 255 FROM_HERE, Bind(&FilePathWatcherFSEvents::ReportError, this, target_)); | |
| 256 } | |
| 257 return changed; | |
| 258 } | |
| 259 | |
| 260 void FilePathWatcherFSEvents::ReportError(const FilePath& target) { | |
| 261 DCHECK(task_runner()->RunsTasksOnCurrentThread()); | |
| 262 if (!callback_.is_null()) { | |
| 263 callback_.Run(target, true); | |
| 264 } | |
| 265 } | |
| 266 | |
| 267 void FilePathWatcherFSEvents::DestroyEventStream() { | |
| 268 FSEventStreamStop(fsevent_stream_); | |
| 269 FSEventStreamInvalidate(fsevent_stream_); | |
| 270 FSEventStreamRelease(fsevent_stream_); | |
| 271 fsevent_stream_ = NULL; | |
| 272 } | |
| 273 | |
| 274 void FilePathWatcherFSEvents::StartEventStream(FSEventStreamEventId start_event, | |
| 275 const FilePath& path) { | |
| 276 DCHECK(g_task_runner.Get().RunsTasksOnCurrentThread()); | |
| 277 DCHECK(resolved_target_.empty()); | |
| 278 | |
| 279 target_ = path; | |
| 280 ResolveTargetPath(); | |
| 281 UpdateEventStream(start_event); | |
| 282 } | |
| 283 | |
| 284 } // namespace base | |
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