base/files/file_path_watcher_linux.cc

   1 // Copyright (c) 2012 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.h"
   6
   7 #include <errno.h>
   8 #include <string.h>
   9 #include <sys/inotify.h>
  10 #include <sys/ioctl.h>
  11 #include <sys/select.h>
  12 #include <unistd.h>
  13
  14 #include <algorithm>
  15 #include <map>
  16 #include <set>
  17 #include <utility>
  18 #include <vector>
  19
  20 #include "base/bind.h"
  21 #include "base/containers/hash_tables.h"
  22 #include "base/files/file_enumerator.h"
  23 #include "base/files/file_path.h"
  24 #include "base/files/file_util.h"
  25 #include "base/lazy_instance.h"
  26 #include "base/location.h"
  27 #include "base/logging.h"
  28 #include "base/memory/scoped_ptr.h"
  29 #include "base/posix/eintr_wrapper.h"
  30 #include "base/single_thread_task_runner.h"
  31 #include "base/synchronization/lock.h"
  32 #include "base/thread_task_runner_handle.h"
  33 #include "base/threading/thread.h"
  34 #include "base/trace_event/trace_event.h"
  35
  36 namespace base {
  37
  38 namespace {
  39
  40 class FilePathWatcherImpl;
  41
  42 // Singleton to manage all inotify watches.
  43 // TODO(tony): It would be nice if this wasn't a singleton.
  44 // http://crbug.com/38174
  45 class InotifyReader {
  46  public:
  47   typedef int Watch;  // Watch descriptor used by AddWatch and RemoveWatch.
  48   static const Watch kInvalidWatch = -1;
  49
  50   // Watch directory |path| for changes. |watcher| will be notified on each
  51   // change. Returns kInvalidWatch on failure.
  52   Watch AddWatch(const FilePath& path, FilePathWatcherImpl* watcher);
  53
  54   // Remove |watch| if it's valid.
  55   void RemoveWatch(Watch watch, FilePathWatcherImpl* watcher);
  56
  57   // Callback for InotifyReaderTask.
  58   void OnInotifyEvent(const inotify_event* event);
  59
  60  private:
  61   friend struct DefaultLazyInstanceTraits<InotifyReader>;
  62
  63   typedef std::set<FilePathWatcherImpl*> WatcherSet;
  64
  65   InotifyReader();
  66   ~InotifyReader();
  67
  68   // We keep track of which delegates want to be notified on which watches.
  69   hash_map<Watch, WatcherSet> watchers_;
  70
  71   // Lock to protect watchers_.
  72   Lock lock_;
  73
  74   // Separate thread on which we run blocking read for inotify events.
  75   Thread thread_;
  76
  77   // File descriptor returned by inotify_init.
  78   const int inotify_fd_;
  79
  80   // Use self-pipe trick to unblock select during shutdown.
  81   int shutdown_pipe_[2];
  82
  83   // Flag set to true when startup was successful.
  84   bool valid_;
  85
  86   DISALLOW_COPY_AND_ASSIGN(InotifyReader);
  87 };
  88
  89 class FilePathWatcherImpl : public FilePathWatcher::PlatformDelegate,
  90                             public MessageLoop::DestructionObserver {
  91  public:
  92   FilePathWatcherImpl();
  93
  94   // Called for each event coming from the watch. |fired_watch| identifies the
  95   // watch that fired, |child| indicates what has changed, and is relative to
  96   // the currently watched path for |fired_watch|.
  97   //
  98   // |created| is true if the object appears.
  99   // |deleted| is true if the object disappears.
 100   // |is_dir| is true if the object is a directory.
 101   void OnFilePathChanged(InotifyReader::Watch fired_watch,
 102                          const FilePath::StringType& child,
 103                          bool created,
 104                          bool deleted,
 105                          bool is_dir);
 106
 107  protected:
 108   ~FilePathWatcherImpl() override {}
 109
 110  private:
 111   // Start watching |path| for changes and notify |delegate| on each change.
 112   // Returns true if watch for |path| has been added successfully.
 113   bool Watch(const FilePath& path,
 114              bool recursive,
 115              const FilePathWatcher::Callback& callback) override;
 116
 117   // Cancel the watch. This unregisters the instance with InotifyReader.
 118   void Cancel() override;
 119
 120   // Cleans up and stops observing the message_loop() thread.
 121   void CancelOnMessageLoopThread() override;
 122
 123   // Deletion of the FilePathWatcher will call Cancel() to dispose of this
 124   // object in the right thread. This also observes destruction of the required
 125   // cleanup thread, in case it quits before Cancel() is called.
 126   void WillDestroyCurrentMessageLoop() override;
 127
 128   // Inotify watches are installed for all directory components of |target_|.
 129   // A WatchEntry instance holds:
 130   // - |watch|: the watch descriptor for a component.
 131   // - |subdir|: the subdirectory that identifies the next component.
 132   //   - For the last component, there is no next component, so it is empty.
 133   // - |linkname|: the target of the symlink.
 134   //   - Only if the target being watched is a symbolic link.
 135   struct WatchEntry {
 136     explicit WatchEntry(const FilePath::StringType& dirname)
 137         : watch(InotifyReader::kInvalidWatch),
 138           subdir(dirname) {}
 139
 140     InotifyReader::Watch watch;
 141     FilePath::StringType subdir;
 142     FilePath::StringType linkname;
 143   };
 144   typedef std::vector<WatchEntry> WatchVector;
 145
 146   // Reconfigure to watch for the most specific parent directory of |target_|
 147   // that exists. Also calls UpdateRecursiveWatches() below.
 148   void UpdateWatches();
 149
 150   // Reconfigure to recursively watch |target_| and all its sub-directories.
 151   // - This is a no-op if the watch is not recursive.
 152   // - If |target_| does not exist, then clear all the recursive watches.
 153   // - Assuming |target_| exists, passing kInvalidWatch as |fired_watch| forces
 154   //   addition of recursive watches for |target_|.
 155   // - Otherwise, only the directory associated with |fired_watch| and its
 156   //   sub-directories will be reconfigured.
 157   void UpdateRecursiveWatches(InotifyReader::Watch fired_watch, bool is_dir);
 158
 159   // Enumerate recursively through |path| and add / update watches.
 160   void UpdateRecursiveWatchesForPath(const FilePath& path);
 161
 162   // Do internal bookkeeping to update mappings between |watch| and its
 163   // associated full path |path|.
 164   void TrackWatchForRecursion(InotifyReader::Watch watch, const FilePath& path);
 165
 166   // Remove all the recursive watches.
 167   void RemoveRecursiveWatches();
 168
 169   // |path| is a symlink to a non-existent target. Attempt to add a watch to
 170   // the link target's parent directory. Update |watch_entry| on success.
 171   void AddWatchForBrokenSymlink(const FilePath& path, WatchEntry* watch_entry);
 172
 173   bool HasValidWatchVector() const;
 174
 175   // Callback to notify upon changes.
 176   FilePathWatcher::Callback callback_;
 177
 178   // The file or directory we're supposed to watch.
 179   FilePath target_;
 180
 181   bool recursive_;
 182
 183   // The vector of watches and next component names for all path components,
 184   // starting at the root directory. The last entry corresponds to the watch for
 185   // |target_| and always stores an empty next component name in |subdir|.
 186   WatchVector watches_;
 187
 188   hash_map<InotifyReader::Watch, FilePath> recursive_paths_by_watch_;
 189   std::map<FilePath, InotifyReader::Watch> recursive_watches_by_path_;
 190
 191   DISALLOW_COPY_AND_ASSIGN(FilePathWatcherImpl);
 192 };
 193
 194 void InotifyReaderCallback(InotifyReader* reader, int inotify_fd,
 195                            int shutdown_fd) {
 196   // Make sure the file descriptors are good for use with select().
 197   CHECK_LE(0, inotify_fd);
 198   CHECK_GT(FD_SETSIZE, inotify_fd);
 199   CHECK_LE(0, shutdown_fd);
 200   CHECK_GT(FD_SETSIZE, shutdown_fd);
 201
 202   trace_event::TraceLog::GetInstance()->SetCurrentThreadBlocksMessageLoop();
 203
 204   while (true) {
 205     fd_set rfds;
 206     FD_ZERO(&rfds);
 207     FD_SET(inotify_fd, &rfds);
 208     FD_SET(shutdown_fd, &rfds);
 209
 210     // Wait until some inotify events are available.
 211     int select_result =
 212       HANDLE_EINTR(select(std::max(inotify_fd, shutdown_fd) + 1,
 213                           &rfds, NULL, NULL, NULL));
 214     if (select_result < 0) {
 215       DPLOG(WARNING) << "select failed";
 216       return;
 217     }
 218
 219     if (FD_ISSET(shutdown_fd, &rfds))
 220       return;
 221
 222     // Adjust buffer size to current event queue size.
 223     int buffer_size;
 224     int ioctl_result = HANDLE_EINTR(ioctl(inotify_fd, FIONREAD,
 225                                           &buffer_size));
 226
 227     if (ioctl_result != 0) {
 228       DPLOG(WARNING) << "ioctl failed";
 229       return;
 230     }
 231
 232     std::vector<char> buffer(buffer_size);
 233
 234     ssize_t bytes_read = HANDLE_EINTR(read(inotify_fd, &buffer[0],
 235                                            buffer_size));
 236
 237     if (bytes_read < 0) {
 238       DPLOG(WARNING) << "read from inotify fd failed";
 239       return;
 240     }
 241
 242     ssize_t i = 0;
 243     while (i < bytes_read) {
 244       inotify_event* event = reinterpret_cast<inotify_event*>(&buffer[i]);
 245       size_t event_size = sizeof(inotify_event) + event->len;
 246       DCHECK(i + event_size <= static_cast<size_t>(bytes_read));
 247       reader->OnInotifyEvent(event);
 248       i += event_size;
 249     }
 250   }
 251 }
 252
 253 static LazyInstance<InotifyReader>::Leaky g_inotify_reader =
 254     LAZY_INSTANCE_INITIALIZER;
 255
 256 InotifyReader::InotifyReader()
 257     : thread_("inotify_reader"),
 258       inotify_fd_(inotify_init()),
 259       valid_(false) {
 260   if (inotify_fd_ < 0)
 261     PLOG(ERROR) << "inotify_init() failed";
 262
 263   shutdown_pipe_[0] = -1;
 264   shutdown_pipe_[1] = -1;
 265   if (inotify_fd_ >= 0 && pipe(shutdown_pipe_) == 0 && thread_.Start()) {
 266     thread_.task_runner()->PostTask(
 267         FROM_HERE,
 268         Bind(&InotifyReaderCallback, this, inotify_fd_, shutdown_pipe_[0]));
 269     valid_ = true;
 270   }
 271 }
 272
 273 InotifyReader::~InotifyReader() {
 274   if (valid_) {
 275     // Write to the self-pipe so that the select call in InotifyReaderTask
 276     // returns.
 277     ssize_t ret = HANDLE_EINTR(write(shutdown_pipe_[1], "", 1));
 278     DPCHECK(ret > 0);
 279     DCHECK_EQ(ret, 1);
 280     thread_.Stop();
 281   }
 282   if (inotify_fd_ >= 0)
 283     close(inotify_fd_);
 284   if (shutdown_pipe_[0] >= 0)
 285     close(shutdown_pipe_[0]);
 286   if (shutdown_pipe_[1] >= 0)
 287     close(shutdown_pipe_[1]);
 288 }
 289
 290 InotifyReader::Watch InotifyReader::AddWatch(
 291     const FilePath& path, FilePathWatcherImpl* watcher) {
 292   if (!valid_)
 293     return kInvalidWatch;
 294
 295   AutoLock auto_lock(lock_);
 296
 297   Watch watch = inotify_add_watch(inotify_fd_, path.value().c_str(),
 298                                   IN_ATTRIB | IN_CREATE | IN_DELETE |
 299                                   IN_CLOSE_WRITE | IN_MOVE |
 300                                   IN_ONLYDIR);
 301
 302   if (watch == kInvalidWatch)
 303     return kInvalidWatch;
 304
 305   watchers_[watch].insert(watcher);
 306
 307   return watch;
 308 }
 309
 310 void InotifyReader::RemoveWatch(Watch watch, FilePathWatcherImpl* watcher) {
 311   if (!valid_ || (watch == kInvalidWatch))
 312     return;
 313
 314   AutoLock auto_lock(lock_);
 315
 316   watchers_[watch].erase(watcher);
 317
 318   if (watchers_[watch].empty()) {
 319     watchers_.erase(watch);
 320     inotify_rm_watch(inotify_fd_, watch);
 321   }
 322 }
 323
 324 void InotifyReader::OnInotifyEvent(const inotify_event* event) {
 325   if (event->mask & IN_IGNORED)
 326     return;
 327
 328   FilePath::StringType child(event->len ? event->name : FILE_PATH_LITERAL(""));
 329   AutoLock auto_lock(lock_);
 330
 331   for (WatcherSet::iterator watcher = watchers_[event->wd].begin();
 332        watcher != watchers_[event->wd].end();
 333        ++watcher) {
 334     (*watcher)->OnFilePathChanged(event->wd,
 335                                   child,
 336                                   event->mask & (IN_CREATE | IN_MOVED_TO),
 337                                   event->mask & (IN_DELETE | IN_MOVED_FROM),
 338                                   event->mask & IN_ISDIR);
 339   }
 340 }
 341
 342 FilePathWatcherImpl::FilePathWatcherImpl()
 343     : recursive_(false) {
 344 }
 345
 346 void FilePathWatcherImpl::OnFilePathChanged(InotifyReader::Watch fired_watch,
 347                                             const FilePath::StringType& child,
 348                                             bool created,
 349                                             bool deleted,
 350                                             bool is_dir) {
 351   if (!task_runner()->BelongsToCurrentThread()) {
 352     // Switch to task_runner() to access |watches_| safely.
 353     task_runner()->PostTask(FROM_HERE,
 354                             Bind(&FilePathWatcherImpl::OnFilePathChanged, this,
 355                                  fired_watch, child, created, deleted, is_dir));
 356     return;
 357   }
 358
 359   // Check to see if CancelOnMessageLoopThread() has already been called.
 360   // May happen when code flow reaches here from the PostTask() above.
 361   if (watches_.empty()) {
 362     DCHECK(target_.empty());
 363     return;
 364   }
 365
 366   DCHECK(MessageLoopForIO::current());
 367   DCHECK(HasValidWatchVector());
 368
 369   // Used below to avoid multiple recursive updates.
 370   bool did_update = false;
 371
 372   // Find the entry in |watches_| that corresponds to |fired_watch|.
 373   for (size_t i = 0; i < watches_.size(); ++i) {
 374     const WatchEntry& watch_entry = watches_[i];
 375     if (fired_watch != watch_entry.watch)
 376       continue;
 377
 378     // Check whether a path component of |target_| changed.
 379     bool change_on_target_path =
 380         child.empty() ||
 381         (child == watch_entry.linkname) ||
 382         (child == watch_entry.subdir);
 383
 384     // Check if the change references |target_| or a direct child of |target_|.
 385     bool target_changed;
 386     if (watch_entry.subdir.empty()) {
 387       // The fired watch is for a WatchEntry without a subdir. Thus for a given
 388       // |target_| = "/path/to/foo", this is for "foo". Here, check either:
 389       // - the target has no symlink: it is the target and it changed.
 390       // - the target has a symlink, and it matches |child|.
 391       target_changed = (watch_entry.linkname.empty() ||
 392                         child == watch_entry.linkname);
 393     } else {
 394       // The fired watch is for a WatchEntry with a subdir. Thus for a given
 395       // |target_| = "/path/to/foo", this is for {"/", "/path", "/path/to"}.
 396       // So we can safely access the next WatchEntry since we have not reached
 397       // the end yet. Check |watch_entry| is for "/path/to", i.e. the next
 398       // element is "foo".
 399       bool next_watch_may_be_for_target = watches_[i + 1].subdir.empty();
 400       if (next_watch_may_be_for_target) {
 401         // The current |watch_entry| is for "/path/to", so check if the |child|
 402         // that changed is "foo".
 403         target_changed = watch_entry.subdir == child;
 404       } else {
 405         // The current |watch_entry| is not for "/path/to", so the next entry
 406         // cannot be "foo". Thus |target_| has not changed.
 407         target_changed = false;
 408       }
 409     }
 410
 411     // Update watches if a directory component of the |target_| path
 412     // (dis)appears. Note that we don't add the additional restriction of
 413     // checking the event mask to see if it is for a directory here as changes
 414     // to symlinks on the target path will not have IN_ISDIR set in the event
 415     // masks. As a result we may sometimes call UpdateWatches() unnecessarily.
 416     if (change_on_target_path && (created || deleted) && !did_update) {
 417       UpdateWatches();
 418       did_update = true;
 419     }
 420
 421     // Report the following events:
 422     //  - The target or a direct child of the target got changed (in case the
 423     //    watched path refers to a directory).
 424     //  - One of the parent directories got moved or deleted, since the target
 425     //    disappears in this case.
 426     //  - One of the parent directories appears. The event corresponding to
 427     //    the target appearing might have been missed in this case, so recheck.
 428     if (target_changed ||
 429         (change_on_target_path && deleted) ||
 430         (change_on_target_path && created && PathExists(target_))) {
 431       if (!did_update) {
 432         UpdateRecursiveWatches(fired_watch, is_dir);
 433         did_update = true;
 434       }
 435       callback_.Run(target_, false /* error */);
 436       return;
 437     }
 438   }
 439
 440   if (ContainsKey(recursive_paths_by_watch_, fired_watch)) {
 441     if (!did_update)
 442       UpdateRecursiveWatches(fired_watch, is_dir);
 443     callback_.Run(target_, false /* error */);
 444   }
 445 }
 446
 447 bool FilePathWatcherImpl::Watch(const FilePath& path,
 448                                 bool recursive,
 449                                 const FilePathWatcher::Callback& callback) {
 450   DCHECK(target_.empty());
 451   DCHECK(MessageLoopForIO::current());
 452
 453   set_task_runner(ThreadTaskRunnerHandle::Get());
 454   callback_ = callback;
 455   target_ = path;
 456   recursive_ = recursive;
 457   MessageLoop::current()->AddDestructionObserver(this);
 458
 459   std::vector<FilePath::StringType> comps;
 460   target_.GetComponents(&comps);
 461   DCHECK(!comps.empty());
 462   for (size_t i = 1; i < comps.size(); ++i)
 463     watches_.push_back(WatchEntry(comps[i]));
 464   watches_.push_back(WatchEntry(FilePath::StringType()));
 465   UpdateWatches();
 466   return true;
 467 }
 468
 469 void FilePathWatcherImpl::Cancel() {
 470   if (callback_.is_null()) {
 471     // Watch was never called, or the message_loop() thread is already gone.
 472     set_cancelled();
 473     return;
 474   }
 475
 476   // Switch to the message_loop() if necessary so we can access |watches_|.
 477   if (!task_runner()->BelongsToCurrentThread()) {
 478     task_runner()->PostTask(FROM_HERE, Bind(&FilePathWatcher::CancelWatch,
 479                                             make_scoped_refptr(this)));
 480   } else {
 481     CancelOnMessageLoopThread();
 482   }
 483 }
 484
 485 void FilePathWatcherImpl::CancelOnMessageLoopThread() {
 486   DCHECK(task_runner()->BelongsToCurrentThread());
 487   set_cancelled();
 488
 489   if (!callback_.is_null()) {
 490     MessageLoop::current()->RemoveDestructionObserver(this);
 491     callback_.Reset();
 492   }
 493
 494   for (size_t i = 0; i < watches_.size(); ++i)
 495     g_inotify_reader.Get().RemoveWatch(watches_[i].watch, this);
 496   watches_.clear();
 497   target_.clear();
 498
 499   if (recursive_)
 500     RemoveRecursiveWatches();
 501 }
 502
 503 void FilePathWatcherImpl::WillDestroyCurrentMessageLoop() {
 504   CancelOnMessageLoopThread();
 505 }
 506
 507 void FilePathWatcherImpl::UpdateWatches() {
 508   // Ensure this runs on the message_loop() exclusively in order to avoid
 509   // concurrency issues.
 510   DCHECK(task_runner()->BelongsToCurrentThread());
 511   DCHECK(HasValidWatchVector());
 512
 513   // Walk the list of watches and update them as we go.
 514   FilePath path(FILE_PATH_LITERAL("/"));
 515   for (size_t i = 0; i < watches_.size(); ++i) {
 516     WatchEntry& watch_entry = watches_[i];
 517     InotifyReader::Watch old_watch = watch_entry.watch;
 518     watch_entry.watch = InotifyReader::kInvalidWatch;
 519     watch_entry.linkname.clear();
 520     watch_entry.watch = g_inotify_reader.Get().AddWatch(path, this);
 521     if (watch_entry.watch == InotifyReader::kInvalidWatch) {
 522       // Ignore the error code (beyond symlink handling) to attempt to add
 523       // watches on accessible children of unreadable directories. Note that
 524       // this is a best-effort attempt; we may not catch events in this
 525       // scenario.
 526       if (IsLink(path))
 527         AddWatchForBrokenSymlink(path, &watch_entry);
 528     }
 529     if (old_watch != watch_entry.watch)
 530       g_inotify_reader.Get().RemoveWatch(old_watch, this);
 531     path = path.Append(watch_entry.subdir);
 532   }
 533
 534   UpdateRecursiveWatches(InotifyReader::kInvalidWatch,
 535                          false /* is directory? */);
 536 }
 537
 538 void FilePathWatcherImpl::UpdateRecursiveWatches(
 539     InotifyReader::Watch fired_watch,
 540     bool is_dir) {
 541   if (!recursive_)
 542     return;
 543
 544   if (!DirectoryExists(target_)) {
 545     RemoveRecursiveWatches();
 546     return;
 547   }
 548
 549   // Check to see if this is a forced update or if some component of |target_|
 550   // has changed. For these cases, redo the watches for |target_| and below.
 551   if (!ContainsKey(recursive_paths_by_watch_, fired_watch)) {
 552     UpdateRecursiveWatchesForPath(target_);
 553     return;
 554   }
 555
 556   // Underneath |target_|, only directory changes trigger watch updates.
 557   if (!is_dir)
 558     return;
 559
 560   const FilePath& changed_dir = recursive_paths_by_watch_[fired_watch];
 561
 562   std::map<FilePath, InotifyReader::Watch>::iterator start_it =
 563       recursive_watches_by_path_.lower_bound(changed_dir);
 564   std::map<FilePath, InotifyReader::Watch>::iterator end_it = start_it;
 565   for (; end_it != recursive_watches_by_path_.end(); ++end_it) {
 566     const FilePath& cur_path = end_it->first;
 567     if (!changed_dir.IsParent(cur_path))
 568       break;
 569     if (!DirectoryExists(cur_path))
 570       g_inotify_reader.Get().RemoveWatch(end_it->second, this);
 571   }
 572   recursive_watches_by_path_.erase(start_it, end_it);
 573   UpdateRecursiveWatchesForPath(changed_dir);
 574 }
 575
 576 void FilePathWatcherImpl::UpdateRecursiveWatchesForPath(const FilePath& path) {
 577   DCHECK(recursive_);
 578   DCHECK(!path.empty());
 579   DCHECK(DirectoryExists(path));
 580
 581   // Note: SHOW_SYM_LINKS exposes symlinks as symlinks, so they are ignored
 582   // rather than followed. Following symlinks can easily lead to the undesirable
 583   // situation where the entire file system is being watched.
 584   FileEnumerator enumerator(
 585       path,
 586       true /* recursive enumeration */,
 587       FileEnumerator::DIRECTORIES | FileEnumerator::SHOW_SYM_LINKS);
 588   for (FilePath current = enumerator.Next();
 589        !current.empty();
 590        current = enumerator.Next()) {
 591     DCHECK(enumerator.GetInfo().IsDirectory());
 592
 593     if (!ContainsKey(recursive_watches_by_path_, current)) {
 594       // Add new watches.
 595       InotifyReader::Watch watch =
 596           g_inotify_reader.Get().AddWatch(current, this);
 597       TrackWatchForRecursion(watch, current);
 598     } else {
 599       // Update existing watches.
 600       InotifyReader::Watch old_watch = recursive_watches_by_path_[current];
 601       DCHECK_NE(InotifyReader::kInvalidWatch, old_watch);
 602       InotifyReader::Watch watch =
 603           g_inotify_reader.Get().AddWatch(current, this);
 604       if (watch != old_watch) {
 605         g_inotify_reader.Get().RemoveWatch(old_watch, this);
 606         recursive_paths_by_watch_.erase(old_watch);
 607         recursive_watches_by_path_.erase(current);
 608         TrackWatchForRecursion(watch, current);
 609       }
 610     }
 611   }
 612 }
 613
 614 void FilePathWatcherImpl::TrackWatchForRecursion(InotifyReader::Watch watch,
 615                                                  const FilePath& path) {
 616   DCHECK(recursive_);
 617   DCHECK(!path.empty());
 618   DCHECK(target_.IsParent(path));
 619
 620   if (watch == InotifyReader::kInvalidWatch)
 621     return;
 622
 623   DCHECK(!ContainsKey(recursive_paths_by_watch_, watch));
 624   DCHECK(!ContainsKey(recursive_watches_by_path_, path));
 625   recursive_paths_by_watch_[watch] = path;
 626   recursive_watches_by_path_[path] = watch;
 627 }
 628
 629 void FilePathWatcherImpl::RemoveRecursiveWatches() {
 630   if (!recursive_)
 631     return;
 632
 633   for (hash_map<InotifyReader::Watch, FilePath>::const_iterator it =
 634            recursive_paths_by_watch_.begin();
 635        it != recursive_paths_by_watch_.end();
 636        ++it) {
 637     g_inotify_reader.Get().RemoveWatch(it->first, this);
 638   }
 639   recursive_paths_by_watch_.clear();
 640   recursive_watches_by_path_.clear();
 641 }
 642
 643 void FilePathWatcherImpl::AddWatchForBrokenSymlink(const FilePath& path,
 644                                                    WatchEntry* watch_entry) {
 645   DCHECK_EQ(InotifyReader::kInvalidWatch, watch_entry->watch);
 646   FilePath link;
 647   if (!ReadSymbolicLink(path, &link))
 648     return;
 649
 650   if (!link.IsAbsolute())
 651     link = path.DirName().Append(link);
 652
 653   // Try watching symlink target directory. If the link target is "/", then we
 654   // shouldn't get here in normal situations and if we do, we'd watch "/" for
 655   // changes to a component "/" which is harmless so no special treatment of
 656   // this case is required.
 657   InotifyReader::Watch watch =
 658       g_inotify_reader.Get().AddWatch(link.DirName(), this);
 659   if (watch == InotifyReader::kInvalidWatch) {
 660     // TODO(craig) Symlinks only work if the parent directory for the target
 661     // exist. Ideally we should make sure we've watched all the components of
 662     // the symlink path for changes. See crbug.com/91561 for details.
 663     DPLOG(WARNING) << "Watch failed for "  << link.DirName().value();
 664     return;
 665   }
 666   watch_entry->watch = watch;
 667   watch_entry->linkname = link.BaseName().value();
 668 }
 669
 670 bool FilePathWatcherImpl::HasValidWatchVector() const {
 671   if (watches_.empty())
 672     return false;
 673   for (size_t i = 0; i < watches_.size() - 1; ++i) {
 674     if (watches_[i].subdir.empty())
 675       return false;
 676   }
 677   return watches_[watches_.size() - 1].subdir.empty();
 678 }
 679
 680 }  // namespace
 681
 682 FilePathWatcher::FilePathWatcher() {
 683   impl_ = new FilePathWatcherImpl();
 684 }
 685
 686 }  // namespace base