| // 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. |
| |
| #include "base/files/file_path_watcher_fsevents.h" |
| |
| #include <dispatch/dispatch.h> |
| |
| #include <list> |
| |
| #include "base/bind.h" |
| #include "base/files/file_util.h" |
| #include "base/lazy_instance.h" |
| #include "base/logging.h" |
| #include "base/mac/scoped_cftyperef.h" |
| #include "base/strings/stringprintf.h" |
| #include "base/threading/sequenced_task_runner_handle.h" |
| |
| namespace base { |
| |
| namespace { |
| |
| // The latency parameter passed to FSEventsStreamCreate(). |
| const CFAbsoluteTime kEventLatencySeconds = 0.3; |
| |
| // Resolve any symlinks in the path. |
| FilePath ResolvePath(const FilePath& path) { |
| const unsigned kMaxLinksToResolve = 255; |
| |
| std::vector<FilePath::StringType> component_vector; |
| path.GetComponents(&component_vector); |
| std::list<FilePath::StringType> |
| components(component_vector.begin(), component_vector.end()); |
| |
| FilePath result; |
| unsigned resolve_count = 0; |
| while (resolve_count < kMaxLinksToResolve && !components.empty()) { |
| FilePath component(*components.begin()); |
| components.pop_front(); |
| |
| FilePath current; |
| if (component.IsAbsolute()) { |
| current = component; |
| } else { |
| current = result.Append(component); |
| } |
| |
| FilePath target; |
| if (ReadSymbolicLink(current, &target)) { |
| if (target.IsAbsolute()) |
| result.clear(); |
| std::vector<FilePath::StringType> target_components; |
| target.GetComponents(&target_components); |
| components.insert(components.begin(), target_components.begin(), |
| target_components.end()); |
| resolve_count++; |
| } else { |
| result = current; |
| } |
| } |
| |
| if (resolve_count >= kMaxLinksToResolve) |
| result.clear(); |
| return result; |
| } |
| |
| } // namespace |
| |
| FilePathWatcherFSEvents::FilePathWatcherFSEvents() |
| : queue_(dispatch_queue_create( |
| base::StringPrintf("org.chromium.base.FilePathWatcher.%p", this) |
| .c_str(), |
| DISPATCH_QUEUE_SERIAL)), |
| fsevent_stream_(nullptr), |
| weak_factory_(this) {} |
| |
| FilePathWatcherFSEvents::~FilePathWatcherFSEvents() { |
| DCHECK(!task_runner() || task_runner()->RunsTasksOnCurrentThread()); |
| DCHECK(callback_.is_null()) |
| << "Cancel() must be called before FilePathWatcher is destroyed."; |
| } |
| |
| bool FilePathWatcherFSEvents::Watch(const FilePath& path, |
| bool recursive, |
| const FilePathWatcher::Callback& callback) { |
| DCHECK(!callback.is_null()); |
| DCHECK(callback_.is_null()); |
| |
| // This class could support non-recursive watches, but that is currently |
| // left to FilePathWatcherKQueue. |
| if (!recursive) |
| return false; |
| |
| set_task_runner(SequencedTaskRunnerHandle::Get()); |
| callback_ = callback; |
| |
| FSEventStreamEventId start_event = FSEventsGetCurrentEventId(); |
| // The block runtime would implicitly capture the reference, not the object |
| // it's referencing. Copy the path into a local, so that the value is |
| // captured by the block's scope. |
| const FilePath path_copy(path); |
| |
| dispatch_async(queue_, ^{ |
| StartEventStream(start_event, path_copy); |
| }); |
| return true; |
| } |
| |
| void FilePathWatcherFSEvents::Cancel() { |
| set_cancelled(); |
| callback_.Reset(); |
| |
| // Switch to the dispatch queue to tear down the event stream. As the queue is |
| // owned by |this|, and this method is called from the destructor, execute the |
| // block synchronously. |
| dispatch_sync(queue_, ^{ |
| if (fsevent_stream_) { |
| DestroyEventStream(); |
| target_.clear(); |
| resolved_target_.clear(); |
| } |
| }); |
| } |
| |
| // static |
| void FilePathWatcherFSEvents::FSEventsCallback( |
| ConstFSEventStreamRef stream, |
| void* event_watcher, |
| size_t num_events, |
| void* event_paths, |
| const FSEventStreamEventFlags flags[], |
| const FSEventStreamEventId event_ids[]) { |
| FilePathWatcherFSEvents* watcher = |
| reinterpret_cast<FilePathWatcherFSEvents*>(event_watcher); |
| bool root_changed = watcher->ResolveTargetPath(); |
| std::vector<FilePath> paths; |
| FSEventStreamEventId root_change_at = FSEventStreamGetLatestEventId(stream); |
| for (size_t i = 0; i < num_events; i++) { |
| if (flags[i] & kFSEventStreamEventFlagRootChanged) |
| root_changed = true; |
| if (event_ids[i]) |
| root_change_at = std::min(root_change_at, event_ids[i]); |
| paths.push_back(FilePath( |
| reinterpret_cast<char**>(event_paths)[i]).StripTrailingSeparators()); |
| } |
| |
| // Reinitialize the event stream if we find changes to the root. This is |
| // necessary since FSEvents doesn't report any events for the subtree after |
| // the directory to be watched gets created. |
| if (root_changed) { |
| // Resetting the event stream from within the callback fails (FSEvents spews |
| // bad file descriptor errors), so do the reset asynchronously. |
| // |
| // We can't dispatch_async a call to UpdateEventStream() directly because |
| // there would be no guarantee that |watcher| still exists when it runs. |
| // |
| // Instead, bounce on task_runner() and use a WeakPtr to verify that |
| // |watcher| still exists. If it does, dispatch_async a call to |
| // UpdateEventStream(). Because the destructor of |watcher| runs on |
| // task_runner() and calls dispatch_sync, it is guaranteed that |watcher| |
| // still exists when UpdateEventStream() runs. |
| watcher->task_runner()->PostTask( |
| FROM_HERE, Bind( |
| [](WeakPtr<FilePathWatcherFSEvents> weak_watcher, |
| FSEventStreamEventId root_change_at) { |
| if (!weak_watcher) |
| return; |
| FilePathWatcherFSEvents* watcher = weak_watcher.get(); |
| dispatch_async(watcher->queue_, ^{ |
| watcher->UpdateEventStream(root_change_at); |
| }); |
| }, |
| watcher->weak_factory_.GetWeakPtr(), root_change_at)); |
| } |
| |
| watcher->OnFilePathsChanged(paths); |
| } |
| |
| void FilePathWatcherFSEvents::OnFilePathsChanged( |
| const std::vector<FilePath>& paths) { |
| DCHECK(!resolved_target_.empty()); |
| task_runner()->PostTask( |
| FROM_HERE, |
| Bind(&FilePathWatcherFSEvents::DispatchEvents, weak_factory_.GetWeakPtr(), |
| paths, target_, resolved_target_)); |
| } |
| |
| void FilePathWatcherFSEvents::DispatchEvents(const std::vector<FilePath>& paths, |
| const FilePath& target, |
| const FilePath& resolved_target) { |
| DCHECK(task_runner()->RunsTasksOnCurrentThread()); |
| |
| // Don't issue callbacks after Cancel() has been called. |
| if (is_cancelled() || callback_.is_null()) { |
| return; |
| } |
| |
| for (const FilePath& path : paths) { |
| if (resolved_target.IsParent(path) || resolved_target == path) { |
| callback_.Run(target, false); |
| return; |
| } |
| } |
| } |
| |
| void FilePathWatcherFSEvents::UpdateEventStream( |
| FSEventStreamEventId start_event) { |
| // It can happen that the watcher gets canceled while tasks that call this |
| // function are still in flight, so abort if this situation is detected. |
| if (resolved_target_.empty()) |
| return; |
| |
| if (fsevent_stream_) |
| DestroyEventStream(); |
| |
| ScopedCFTypeRef<CFStringRef> cf_path(CFStringCreateWithCString( |
| NULL, resolved_target_.value().c_str(), kCFStringEncodingMacHFS)); |
| ScopedCFTypeRef<CFStringRef> cf_dir_path(CFStringCreateWithCString( |
| NULL, resolved_target_.DirName().value().c_str(), |
| kCFStringEncodingMacHFS)); |
| CFStringRef paths_array[] = { cf_path.get(), cf_dir_path.get() }; |
| ScopedCFTypeRef<CFArrayRef> watched_paths(CFArrayCreate( |
| NULL, reinterpret_cast<const void**>(paths_array), arraysize(paths_array), |
| &kCFTypeArrayCallBacks)); |
| |
| FSEventStreamContext context; |
| context.version = 0; |
| context.info = this; |
| context.retain = NULL; |
| context.release = NULL; |
| context.copyDescription = NULL; |
| |
| fsevent_stream_ = FSEventStreamCreate(NULL, &FSEventsCallback, &context, |
| watched_paths, |
| start_event, |
| kEventLatencySeconds, |
| kFSEventStreamCreateFlagWatchRoot); |
| FSEventStreamSetDispatchQueue(fsevent_stream_, queue_); |
| |
| if (!FSEventStreamStart(fsevent_stream_)) { |
| task_runner()->PostTask(FROM_HERE, |
| Bind(&FilePathWatcherFSEvents::ReportError, |
| weak_factory_.GetWeakPtr(), target_)); |
| } |
| } |
| |
| bool FilePathWatcherFSEvents::ResolveTargetPath() { |
| FilePath resolved = ResolvePath(target_).StripTrailingSeparators(); |
| bool changed = resolved != resolved_target_; |
| resolved_target_ = resolved; |
| if (resolved_target_.empty()) { |
| task_runner()->PostTask(FROM_HERE, |
| Bind(&FilePathWatcherFSEvents::ReportError, |
| weak_factory_.GetWeakPtr(), target_)); |
| } |
| return changed; |
| } |
| |
| void FilePathWatcherFSEvents::ReportError(const FilePath& target) { |
| DCHECK(task_runner()->RunsTasksOnCurrentThread()); |
| if (!callback_.is_null()) { |
| callback_.Run(target, true); |
| } |
| } |
| |
| void FilePathWatcherFSEvents::DestroyEventStream() { |
| FSEventStreamStop(fsevent_stream_); |
| FSEventStreamInvalidate(fsevent_stream_); |
| FSEventStreamRelease(fsevent_stream_); |
| fsevent_stream_ = NULL; |
| } |
| |
| void FilePathWatcherFSEvents::StartEventStream(FSEventStreamEventId start_event, |
| const FilePath& path) { |
| DCHECK(resolved_target_.empty()); |
| |
| target_ = path; |
| ResolveTargetPath(); |
| UpdateEventStream(start_event); |
| } |
| |
| } // namespace base |