[4/4][Ozone-Drm] Keep track of DRM devices in browser process

ui/ozone/platform/drm/host/drm_device_handle.cc

+// Copyright 2015 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 "ui/ozone/platform/drm/host/drm_device_handle.h"
+
+#include <xf86drm.h>
+#include <xf86drmMode.h>
+
+#include "base/files/file_path.h"
+
+namespace ui {
+
+namespace {
+
+bool Authenticate(int fd) {
+  drm_magic_t magic;
+  memset(&magic, 0, sizeof(magic));
+  // We need to make sure the DRM device has enough privilege. Use the DRM
+  // authentication logic to figure out if the device has enough permissions.
+  return !drmGetMagic(fd, &magic) && !drmAuthMagic(fd, magic);
+}
+
+}  // namespace
+
+DrmDeviceHandle::DrmDeviceHandle() {
+}
+
+DrmDeviceHandle::~DrmDeviceHandle() {
+}
+
+bool DrmDeviceHandle::Initialize(const base::FilePath& path) {
+  bool print_warning = true;
+  while (true) {
+    file_ = base::File(path, base::File::FLAG_OPEN | base::File::FLAG_READ |

[spang, 2015/04/27 22:23:15]

The base::File abstraction provides little to no benefit here and has real
downsides (such as hiding the error code).

I think we should just call open().

[dnicoara, 2015/04/28 16:26:15]

Done.

+                                 base::File::FLAG_WRITE);
+
+    base::File::Info info;
+    file_.GetInfo(&info);
+
+    CHECK(!info.is_directory);
+    CHECK(path.DirName() == base::FilePath("/dev/dri"));
+
+    if (!file_.IsValid()) {
+      LOG(ERROR) << "Failed to open " << path.value() << ": "
+                 << base::File::ErrorToString(file_.error_details());
+      return false;
+    }
+
+    if (Authenticate(file_.GetPlatformFile()))
+      break;
+
+    LOG_IF(WARNING, print_warning) << "Failed to authenticate " << path.value();
+    print_warning = false;
+    usleep(100000);
+  }
+
+  VLOG(1) << "Succeeded authenticating " << path.value();
+  return true;
+}
+
+void DrmDeviceHandle::Shutdown() {
+  file_.Close();
+}
+
+bool DrmDeviceHandle::IsValid() const {
+  return file_.IsValid();
+}
+
+base::File DrmDeviceHandle::DuplicateFile() {
+  DCHECK(file_.IsValid());
+  return file_.Duplicate();
+}
+
+}  // namespace ui