upload android base code part6

android/system/update_engine/utils_android.cc

@@ -0,0 +1,66 @@
+//
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include "update_engine/utils_android.h"
+
+#include <cutils/properties.h>
+#include <fs_mgr.h>
+
+using std::string;
+
+namespace chromeos_update_engine {
+
+namespace {
+
+// Open the appropriate fstab file and fallback to /fstab.device if
+// that's what's being used.
+static struct fstab* OpenFSTab() {
+  struct fstab* fstab = fs_mgr_read_fstab_default();
+  if (fstab != nullptr)
+    return fstab;
+
+  fstab = fs_mgr_read_fstab("/fstab.device");
+  return fstab;
+}
+
+}  // namespace
+
+namespace utils {
+
+bool DeviceForMountPoint(const string& mount_point, base::FilePath* device) {
+  struct fstab* fstab;
+  struct fstab_rec* record;
+
+  fstab = OpenFSTab();
+  if (fstab == nullptr) {
+    LOG(ERROR) << "Error opening fstab file.";
+    return false;
+  }
+  record = fs_mgr_get_entry_for_mount_point(fstab, mount_point.c_str());
+  if (record == nullptr) {
+    LOG(ERROR) << "Error finding " << mount_point << " entry in fstab file.";
+    fs_mgr_free_fstab(fstab);
+    return false;
+  }
+
+  *device = base::FilePath(record->blk_device);
+  fs_mgr_free_fstab(fstab);
+  return true;
+}
+
+}  // namespace utils
+
+}  // namespace chromeos_update_engine