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admin/node_modules/@parcel/watcher/src/macos/FSEventsBackend.cc

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+#include <CoreServices/CoreServices.h>
+#include <sys/stat.h>
+#include <string>
+#include <fstream>
+#include <unordered_set>
+#include "../Event.hh"
+#include "../Backend.hh"
+#include "./FSEventsBackend.hh"
+#include "../Watcher.hh"
+
+#define CONVERT_TIME(ts) ((uint64_t)ts.tv_sec * 1000000000 + ts.tv_nsec)
+#define IGNORED_FLAGS (kFSEventStreamEventFlagItemIsHardlink | kFSEventStreamEventFlagItemIsLastHardlink | kFSEventStreamEventFlagItemIsSymlink | kFSEventStreamEventFlagItemIsDir | kFSEventStreamEventFlagItemIsFile)
+
+void stopStream(FSEventStreamRef stream, CFRunLoopRef runLoop) {
+  FSEventStreamStop(stream);
+  FSEventStreamUnscheduleFromRunLoop(stream, runLoop, kCFRunLoopDefaultMode);
+  FSEventStreamInvalidate(stream);
+  FSEventStreamRelease(stream);
+}
+
+// macOS has a case insensitive file system by default. In order to detect
+// file renames that only affect case, we need to get the canonical path
+// and compare it with the input path to determine if a file was created or deleted.
+bool pathExists(char *path) {
+  int fd = open(path, O_RDONLY | O_SYMLINK);
+  if (fd == -1) {
+    return false;
+  }
+
+  char buf[PATH_MAX];
+  if (fcntl(fd, F_GETPATH, buf) == -1) {
+    close(fd);
+    return false;
+  }
+
+  bool res = strncmp(path, buf, PATH_MAX) == 0;
+  close(fd);
+  return res;
+}
+
+class State: public WatcherState {
+public:
+  FSEventStreamRef stream;
+  std::shared_ptr<DirTree> tree;
+  uint64_t since;
+};
+
+void FSEventsCallback(
+  ConstFSEventStreamRef streamRef,
+  void *clientCallBackInfo,
+  size_t numEvents,
+  void *eventPaths,
+  const FSEventStreamEventFlags eventFlags[],
+  const FSEventStreamEventId eventIds[]
+) {
+  char **paths = (char **)eventPaths;
+  std::shared_ptr<Watcher>& watcher = *static_cast<std::shared_ptr<Watcher> *>(clientCallBackInfo);
+
+  EventList& list = watcher->mEvents;
+  if (watcher->state == nullptr) {
+      return;
+  }
+
+  auto stateGuard = watcher->state;
+  auto* state = static_cast<State*>(stateGuard.get());
+  uint64_t since = state->since;
+  bool deletedRoot = false;
+
+  for (size_t i = 0; i < numEvents; ++i) {
+    bool isCreated = (eventFlags[i] & kFSEventStreamEventFlagItemCreated) == kFSEventStreamEventFlagItemCreated;
+    bool isRemoved = (eventFlags[i] & kFSEventStreamEventFlagItemRemoved) == kFSEventStreamEventFlagItemRemoved;
+    bool isModified = (eventFlags[i] & kFSEventStreamEventFlagItemModified) == kFSEventStreamEventFlagItemModified ||
+                      (eventFlags[i] & kFSEventStreamEventFlagItemInodeMetaMod) == kFSEventStreamEventFlagItemInodeMetaMod ||
+                      (eventFlags[i] & kFSEventStreamEventFlagItemFinderInfoMod) == kFSEventStreamEventFlagItemFinderInfoMod ||
+                      (eventFlags[i] & kFSEventStreamEventFlagItemChangeOwner) == kFSEventStreamEventFlagItemChangeOwner ||
+                      (eventFlags[i] & kFSEventStreamEventFlagItemXattrMod) == kFSEventStreamEventFlagItemXattrMod;
+    bool isRenamed = (eventFlags[i] & kFSEventStreamEventFlagItemRenamed) == kFSEventStreamEventFlagItemRenamed;
+    bool isDone = (eventFlags[i] & kFSEventStreamEventFlagHistoryDone) == kFSEventStreamEventFlagHistoryDone;
+    bool isDir = (eventFlags[i] & kFSEventStreamEventFlagItemIsDir) == kFSEventStreamEventFlagItemIsDir;
+
+
+    if (eventFlags[i] & kFSEventStreamEventFlagMustScanSubDirs) {
+      if (eventFlags[i] & kFSEventStreamEventFlagUserDropped) {
+        list.error("Events were dropped by the FSEvents client. File system must be re-scanned.");
+      } else if (eventFlags[i] & kFSEventStreamEventFlagKernelDropped) {
+        list.error("Events were dropped by the kernel. File system must be re-scanned.");
+      } else {
+        list.error("Too many events. File system must be re-scanned.");
+      }
+    }
+
+    if (isDone) {
+      watcher->notify();
+      break;
+    }
+
+    auto ignoredFlags = IGNORED_FLAGS;
+    if (__builtin_available(macOS 10.13, *)) {
+      ignoredFlags |= kFSEventStreamEventFlagItemCloned;
+    }
+
+    // If we don't care about any of the flags that are set, ignore this event.
+    if ((eventFlags[i] & ~ignoredFlags) == 0) {
+      continue;
+    }
+
+    // FSEvents exclusion paths only apply to files, not directories.
+    if (watcher->isIgnored(paths[i])) {
+      continue;
+    }
+
+    // Handle unambiguous events first
+    if (isCreated && !(isRemoved || isModified || isRenamed)) {
+      state->tree->add(paths[i], 0, isDir);
+      list.create(paths[i]);
+    } else if (isRemoved && !(isCreated || isModified || isRenamed)) {
+      state->tree->remove(paths[i]);
+      list.remove(paths[i]);
+      if (paths[i] == watcher->mDir) {
+        deletedRoot = true;
+      }
+    } else if (isModified && !(isCreated || isRemoved || isRenamed)) {
+      struct stat file;
+      if (stat(paths[i], &file)) {
+        continue;
+      }
+
+      // Ignore if mtime is the same as the last event.
+      // This prevents duplicate events from being emitted.
+      // If tv_nsec is zero, the file system probably only has second-level
+      // granularity so allow the even through in that case.
+      uint64_t mtime = CONVERT_TIME(file.st_mtimespec);
+      DirEntry *entry = state->tree->find(paths[i]);
+      if (entry && mtime == entry->mtime && file.st_mtimespec.tv_nsec != 0) {
+        continue;
+      }
+
+      if (entry) {
+        // Update mtime.
+        entry->mtime = mtime;
+      } else {
+        // Add to tree if this path has not been discovered yet.
+        state->tree->add(paths[i], mtime, S_ISDIR(file.st_mode));
+      }
+
+      list.update(paths[i]);
+    } else {
+      // If multiple flags were set, then we need to call `stat` to determine if the file really exists.
+      // This helps disambiguate creates, updates, and deletes.
+      struct stat file;
+      if (stat(paths[i], &file) || !pathExists(paths[i])) {
+        // File does not exist, so we have to assume it was removed. This is not exact since the
+        // flags set by fsevents get coalesced together (e.g. created & deleted), so there is no way to
+        // know whether the create and delete both happened since our snapshot (in which case
+        // we'd rather ignore this event completely). This will result in some extra delete events
+        // being emitted for files we don't know about, but that is the best we can do.
+        state->tree->remove(paths[i]);
+        list.remove(paths[i]);
+        if (paths[i] == watcher->mDir) {
+          deletedRoot = true;
+        }
+        continue;
+      }
+
+      // If the file was modified, and existed before, then this is an update, otherwise a create.
+      uint64_t ctime = CONVERT_TIME(file.st_birthtimespec);
+      uint64_t mtime = CONVERT_TIME(file.st_mtimespec);
+      DirEntry *entry = !since ? state->tree->find(paths[i]) : NULL;
+      if (entry && entry->mtime == mtime && file.st_mtimespec.tv_nsec != 0) {
+        continue;
+      }
+
+      // Some mounted file systems report a creation time of 0/unix epoch which we special case.
+      if (isModified && (entry || (ctime <= since && ctime != 0))) {
+        state->tree->update(paths[i], mtime);
+        list.update(paths[i]);
+      } else {
+        state->tree->add(paths[i], mtime, S_ISDIR(file.st_mode));
+        list.create(paths[i]);
+      }
+    }
+  }
+
+  if (!since) {
+    watcher->notify();
+  }
+
+  // Stop watching if the root directory was deleted.
+  if (deletedRoot) {
+    stopStream((FSEventStreamRef)streamRef, CFRunLoopGetCurrent());
+    watcher->state = nullptr;
+  }
+}
+
+void checkWatcher(WatcherRef watcher) {
+  struct stat file;
+  if (stat(watcher->mDir.c_str(), &file)) {
+    throw WatcherError(strerror(errno), watcher);
+  }
+
+  if (!S_ISDIR(file.st_mode)) {
+    throw WatcherError(strerror(ENOTDIR), watcher);
+  }
+}
+
+void FSEventsBackend::startStream(WatcherRef watcher, FSEventStreamEventId id) {
+  checkWatcher(watcher);
+
+  CFAbsoluteTime latency = 0.001;
+  CFStringRef fileWatchPath = CFStringCreateWithCString(
+    NULL,
+    watcher->mDir.c_str(),
+    kCFStringEncodingUTF8
+  );
+
+  CFArrayRef pathsToWatch = CFArrayCreate(
+    NULL,
+    (const void **)&fileWatchPath,
+    1,
+    NULL
+  );
+
+  // Make a watcher reference we can pass into the callback. This ensures bumped ref-count.
+  std::shared_ptr<Watcher>* callbackWatcher = new std::shared_ptr<Watcher> (watcher);
+  FSEventStreamContext callbackInfo {0, static_cast<void*> (callbackWatcher), nullptr, nullptr, nullptr};
+  FSEventStreamRef stream = FSEventStreamCreate(
+    NULL,
+    &FSEventsCallback,
+    &callbackInfo,
+    pathsToWatch,
+    id,
+    latency,
+    kFSEventStreamCreateFlagFileEvents
+  );
+
+  CFMutableArrayRef exclusions = CFArrayCreateMutable(NULL, watcher->mIgnorePaths.size(), NULL);
+  for (auto it = watcher->mIgnorePaths.begin(); it != watcher->mIgnorePaths.end(); it++) {
+    CFStringRef path = CFStringCreateWithCString(
+      NULL,
+      it->c_str(),
+      kCFStringEncodingUTF8
+    );
+
+    CFArrayAppendValue(exclusions, (const void *)path);
+  }
+
+  FSEventStreamSetExclusionPaths(stream, exclusions);
+
+  FSEventStreamScheduleWithRunLoop(stream, mRunLoop, kCFRunLoopDefaultMode);
+  bool started = FSEventStreamStart(stream);
+
+  CFRelease(pathsToWatch);
+  CFRelease(fileWatchPath);
+
+  if (!started) {
+    FSEventStreamRelease(stream);
+    throw WatcherError("Error starting FSEvents stream", watcher);
+  }
+
+  auto stateGuard = watcher->state;
+  State* s = static_cast<State*>(stateGuard.get());
+  s->tree = std::make_shared<DirTree>(watcher->mDir);
+  s->stream = stream;
+}
+
+void FSEventsBackend::start() {
+  mRunLoop = CFRunLoopGetCurrent();
+  CFRetain(mRunLoop);
+
+  // Unlock once run loop has started.
+  CFRunLoopPerformBlock(mRunLoop, kCFRunLoopDefaultMode, ^ {
+    notifyStarted();
+  });
+
+  CFRunLoopWakeUp(mRunLoop);
+  CFRunLoopRun();
+}
+
+FSEventsBackend::~FSEventsBackend() {
+  std::unique_lock<std::mutex> lock(mMutex);
+  CFRunLoopStop(mRunLoop);
+  CFRelease(mRunLoop);
+}
+
+void FSEventsBackend::writeSnapshot(WatcherRef watcher, std::string *snapshotPath) {
+  std::unique_lock<std::mutex> lock(mMutex);
+  checkWatcher(watcher);
+
+  FSEventStreamEventId id = FSEventsGetCurrentEventId();
+  std::ofstream ofs(*snapshotPath);
+  ofs << id;
+  ofs << "\n";
+
+  struct timespec now;
+  clock_gettime(CLOCK_REALTIME, &now);
+  ofs << CONVERT_TIME(now);
+}
+
+void FSEventsBackend::getEventsSince(WatcherRef watcher, std::string *snapshotPath) {
+  std::unique_lock<std::mutex> lock(mMutex);
+  std::ifstream ifs(*snapshotPath);
+  if (ifs.fail()) {
+    return;
+  }
+
+  FSEventStreamEventId id;
+  uint64_t since;
+  ifs >> id;
+  ifs >> since;
+
+  auto s = std::make_shared<State>();
+  s->since = since;
+  watcher->state = s;
+
+  startStream(watcher, id);
+  watcher->wait();
+  stopStream(s->stream, mRunLoop);
+
+  watcher->state = nullptr;
+}
+
+// This function is called by Backend::watch which takes a lock on mMutex
+void FSEventsBackend::subscribe(WatcherRef watcher) {
+  auto s = std::make_shared<State>();
+  s->since = 0;
+  watcher->state = s;
+  startStream(watcher, kFSEventStreamEventIdSinceNow);
+}
+
+// This function is called by Backend::unwatch which takes a lock on mMutex
+void FSEventsBackend::unsubscribe(WatcherRef watcher) {
+  auto stateGuard = watcher->state;
+  State* s = static_cast<State*>(stateGuard.get());
+  if (s != nullptr) {
+    stopStream(s->stream, mRunLoop);
+    watcher->state = nullptr;
+  }
+}

admin/node_modules/@parcel/watcher/src/macos/FSEventsBackend.hh

@@ -0,0 +1,20 @@
+#ifndef FS_EVENTS_H
+#define FS_EVENTS_H
+
+#include <CoreServices/CoreServices.h>
+#include "../Backend.hh"
+
+class FSEventsBackend : public Backend {
+public:
+  void start() override;
+  ~FSEventsBackend();
+  void writeSnapshot(WatcherRef watcher, std::string *snapshotPath) override;
+  void getEventsSince(WatcherRef watcher, std::string *snapshotPath) override;
+  void subscribe(WatcherRef watcher) override;
+  void unsubscribe(WatcherRef watcher) override;
+private:
+  void startStream(WatcherRef watcher, FSEventStreamEventId id);
+  CFRunLoopRef mRunLoop;
+};
+
+#endif