Add FileSystemWatcher class to dart:io.

runtime/bin/file_system_watcher_win.cc

Index: runtime/bin/file_system_watcher_win.cc
diff --git a/runtime/bin/file_system_watcher_win.cc b/runtime/bin/file_system_watcher_win.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5aaf90b4e01bdf72d98532ac979f2b75eeb4307a
--- /dev/null
+++ b/runtime/bin/file_system_watcher_win.cc
@@ -0,0 +1,116 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "platform/globals.h"
+#if defined(TARGET_OS_WINDOWS)
+
+#include "bin/file_system_watcher.h"
+#include "bin/eventhandler.h"
+
+#include <WinIoCtl.h>  // NOLINT
+
+#include "bin/builtin.h"
+#include "bin/log.h"
+#include "bin/utils.h"
+
+
+namespace dart {
+namespace bin {
+
+intptr_t FileSystemWatcher::Init() {
+  return 0;
+}
+
+
+void FileSystemWatcher::Stop(intptr_t id) {
+  // Nothing to do.
+}
+
+
+intptr_t FileSystemWatcher::GetSocketId(intptr_t id, intptr_t path_id) {
+  return path_id;
+}
+
+
+intptr_t FileSystemWatcher::AddPath(intptr_t id,
+                                    const char* path,
+                                    int events,
+                                    bool recursive) {
+  const wchar_t* name = StringUtils::Utf8ToWide(path);
+  HANDLE dir = CreateFileW(name,
+                           FILE_LIST_DIRECTORY,
+                           FILE_SHARE_READ |
+                               FILE_SHARE_WRITE |
+                               FILE_SHARE_DELETE,
+                           NULL,
+                           OPEN_EXISTING,
+                           FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OVERLAPPED,
+                           NULL);
+  free(const_cast<wchar_t*>(name));
+
+  if (dir == INVALID_HANDLE_VALUE) {
+    return 0;
+  }
+
+  int list_events = 0;
+  if (events & (kCreate | kMove | kDelete)) {
+    list_events |= FILE_NOTIFY_CHANGE_FILE_NAME |
+                   FILE_NOTIFY_CHANGE_DIR_NAME;
+  }
+  if (events & kModifyContent) list_events |= FILE_NOTIFY_CHANGE_LAST_WRITE;
+
+  return reinterpret_cast<intptr_t>(
+      new DirectoryWatchHandle(dir, list_events, recursive));
+}
+
+
+bool FileSystemWatcher::RemovePath(intptr_t id, intptr_t path_id) {
+  return true;
+}
+
+intptr_t FileSystemWatcher::ReadEvents(intptr_t id,
+                                       intptr_t path_id,
+                                       Event** events) {
+  const intptr_t kEventSize = sizeof(FILE_NOTIFY_INFORMATION);
+  DirectoryWatchHandle* dir = reinterpret_cast<DirectoryWatchHandle*>(path_id);
+  intptr_t available = dir->Available();
+  intptr_t max_count = available / kEventSize + 1;
+  *events = new Event[max_count];
+  uint8_t* buffer = new uint8_t[available];
+  intptr_t bytes = dir->Read(buffer, available);
+  intptr_t offset = 0;
+  intptr_t i = 0;
+  while (offset < bytes) {
+    FILE_NOTIFY_INFORMATION* e =
+        reinterpret_cast<FILE_NOTIFY_INFORMATION*>(buffer + offset);
+
+    Event* event = *events + i;
+    event->path_id = path_id;
+    event->link = 1;  // Move events come in pairs. Just 'enable' by default.
+    event->event = 0;
+    if (e->Action == FILE_ACTION_ADDED) event->event |= kCreate;
+    if (e->Action == FILE_ACTION_REMOVED) event->event |= kDelete;
+    if (e->Action == FILE_ACTION_MODIFIED) event->event |= kModifyContent;
+    if (e->Action == FILE_ACTION_RENAMED_OLD_NAME) event->event |= kMove;
+    if (e->Action == FILE_ACTION_RENAMED_NEW_NAME) event->event |= kMove;
+    // Copy to include tailing \0.
+    intptr_t len = e->FileNameLength;
+    wchar_t* name = new wchar_t[len / 2 + 1];
+    memcpy(name, e->FileName, len + 1);
+    name[len / 2] = 0;
+    event->filename = StringUtils::WideToUtf8(name);
+    delete[] name;
+
+    i++;
+    if (e->NextEntryOffset == 0) break;
+    offset += e->NextEntryOffset;
+  }
+  delete[] buffer;
+  return i;
+}
+
+}  // namespace bin
+}  // namespace dart
+
+#endif  // defined(TARGET_OS_WINDOWS)