[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 <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <xf86drm.h>
+#include <xf86drmMode.h>
+
+#include "base/files/file_path.h"
+#include "base/posix/eintr_wrapper.h"
+#include "base/threading/thread_restrictions.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() {
+  base::ThreadRestrictions::AssertIOAllowed();
+}
+
+bool DrmDeviceHandle::Initialize(const base::FilePath& path) {
+  CHECK(path.DirName() == base::FilePath("/dev/dri"));
+  base::ThreadRestrictions::AssertIOAllowed();
+  bool print_warning = true;
+  while (true) {
+    file_.reset();
+    int fd = HANDLE_EINTR(open(path.value().c_str(), O_RDWR | O_CLOEXEC));
+    if (fd < 0) {
+      PLOG(ERROR) << "Failed to open " << path.value();
+      return false;
+    }
+
+    file_.reset(fd);
+    struct stat64 file_info;
+    if (fstat64(fd, &file_info)) {
+      PLOG(ERROR) << "Failed to get file info " << path.value();
+      continue;
+    }
+
+    CHECK(!S_ISDIR(file_info.st_mode));
+
+    if (Authenticate(file_.get()))
+      break;
+
+    LOG_IF(WARNING, print_warning) << "Failed to authenticate " << path.value();
+    print_warning = false;
+    usleep(100000);
+  }
+
+  VLOG(1) << "Succeeded authenticating " << path.value();
+  return true;
+}
+
+bool DrmDeviceHandle::IsValid() const {
+  return file_.is_valid();
+}
+
+base::ScopedFD DrmDeviceHandle::Duplicate() {
+  DCHECK(file_.is_valid());
+  int fd = dup(file_.get());
+  if (fd < 0) {
+    PLOG(ERROR) << "Failed to dup";
+    return base::ScopedFD();
+  }
+
+  return base::ScopedFD(fd);
+}
+
+}  // namespace ui