1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include <string> 18 19 #include <android-base/file.h> 20 #include <android-base/stringprintf.h> 21 #include <android-base/strings.h> 22 #include <android-base/properties.h> 23 24 #include "fs_mgr_priv.h" 25 26 // Tries to get the given boot config value from kernel cmdline. 27 // Returns true if successfully found, false otherwise. 28 bool fs_mgr_get_boot_config_from_kernel_cmdline(const std::string& key, std::string* out_val) { 29 FS_MGR_CHECK(out_val != nullptr); 30 31 std::string cmdline; 32 std::string cmdline_key("androidboot." + key); 33 if (android::base::ReadFileToString("/proc/cmdline", &cmdline)) { 34 for (const auto& entry : android::base::Split(android::base::Trim(cmdline), " ")) { 35 std::vector<std::string> pieces = android::base::Split(entry, "="); 36 if (pieces.size() == 2) { 37 if (pieces[0] == cmdline_key) { 38 *out_val = pieces[1]; 39 return true; 40 } 41 } 42 } 43 } 44 45 return false; 46 } 47 48 // Tries to get the boot config value in properties, kernel cmdline and 49 // device tree (in that order). returns 'true' if successfully found, 'false' 50 // otherwise 51 bool fs_mgr_get_boot_config(const std::string& key, std::string* out_val) { 52 FS_MGR_CHECK(out_val != nullptr); 53 54 // first check if we have "ro.boot" property already 55 *out_val = android::base::GetProperty("ro.boot." + key, ""); 56 if (!out_val->empty()) { 57 return true; 58 } 59 60 // fallback to kernel cmdline, properties may not be ready yet 61 if (fs_mgr_get_boot_config_from_kernel_cmdline(key, out_val)) { 62 return true; 63 } 64 65 // lastly, check the device tree 66 if (is_dt_compatible()) { 67 std::string file_name = get_android_dt_dir() + "/" + key; 68 if (android::base::ReadFileToString(file_name, out_val)) { 69 if (!out_val->empty()) { 70 out_val->pop_back(); // Trims the trailing '\0' out. 71 return true; 72 } 73 } 74 } 75 76 return false; 77 } 78
