Add FileSystemWatcher class to dart:io.

runtime/bin/file_system_watcher_linux.cc

+// 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_LINUX)
+
+#include "bin/file_system_watcher.h"
+
+#include <errno.h>  // NOLINT
+#include <sys/inotify.h>  // NOLINT
+
+
+namespace dart {
+namespace bin {
+
+intptr_t FileSystemWatcher::WatchPath(const char* path,
+                                      int events,
+                                      bool recursive) {
+  int fd = TEMP_FAILURE_RETRY(inotify_init1(IN_NONBLOCK | IN_CLOEXEC));
+  if (fd < 0) return -1;
+  int list_events = 0;
+  if (events & kCreate) list_events |= IN_CREATE;
+  if (events & kModifyContent) list_events |= IN_MODIFY | IN_ATTRIB;
+  if (events & kDelete) list_events |= IN_DELETE;
+  if (events & kMove) list_events |= IN_MOVE;
+  int path_fd = TEMP_FAILURE_RETRY(inotify_add_watch(fd, path, list_events));
+  if (path_fd < 0) {
+    close(fd);
+    return -1;
+  }
+  return fd;
+}
+
+
+void FileSystemWatcher::UnwatchPath(intptr_t id) {
+  // Nothing to do.
+}
+
+
+intptr_t FileSystemWatcher::GetSocketId(intptr_t id) {
+  return id;
+}
+
+
+intptr_t FileSystemWatcher::ReadEvents(intptr_t id, Event** events) {

[Søren Gjesse, 2013/08/26 07:51:55]

Here we should just pass in the _NativeSocket object and pull out the fd.

[Anders Johnsen, 2013/09/03 11:36:23]

I've tried to clean up as much as possible by using NativeFieldWrapperClass1.

+  const intptr_t kEventSize = sizeof(struct inotify_event);
+  const intptr_t kBufferSize = kEventSize + NAME_MAX + 1;
+  uint8_t buffer[kBufferSize];
+  intptr_t bytes = TEMP_FAILURE_RETRY(read(id, buffer, kBufferSize));
+  if (bytes < 0) return -1;
+  const intptr_t kMaxCount = kBufferSize / kEventSize + 1;
+  *events = new Event[kMaxCount];

[Søren Gjesse, 2013/08/26 07:51:55]

I think we should just do the Dart allocation in here and avoid the Events
object. Then we can also get rid of the strdup below and the related freeing.

[Anders Johnsen, 2013/09/03 11:36:23]

Done.

+  intptr_t offset = 0;
+  intptr_t i = 0;
+  while (offset < bytes) {
+    struct inotify_event* e =
+        reinterpret_cast<struct inotify_event*>(buffer + offset);
+    Event* event = *events + i;
+    event->event = 0;
+    event->link = e->cookie;
+    if (e->mask & IN_MODIFY) event->event |= kModifyContent;
+    if (e->mask & IN_ATTRIB) event->event |= kModefyAttribute;
+    if (e->mask & IN_CREATE) event->event |= kCreate;
+    if (e->mask & IN_MOVE) event->event |= kMove;
+    if (e->mask & IN_DELETE) event->event |= kDelete;
+    if (e->len > 0) {
+      event->filename = strdup(e->name);
+    } else {
+      event->filename = NULL;
+    }
+    i++;
+    offset += kEventSize + e->len;
+  }
+  return i;
+}
+
+}  // namespace bin
+}  // namespace dart
+
+#endif  // defined(TARGET_OS_LINUX)
+