| /* |
| * Copyright (C) 2017 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 <algorithm> |
| #include <iterator> |
| #include <string> |
| #include <vector> |
| |
| #include <android-base/file.h> |
| #include <android-base/stringprintf.h> |
| #include <android-base/strings.h> |
| #include <android-base/properties.h> |
| |
| #include "fs_mgr_priv.h" |
| |
| std::vector<std::pair<std::string, std::string>> fs_mgr_parse_boot_config(const std::string& cmdline) { |
| static constexpr char quote = '"'; |
| |
| std::vector<std::pair<std::string, std::string>> result; |
| size_t base = 0; |
| while (true) { |
| // skip quoted spans |
| auto found = base; |
| while (((found = cmdline.find_first_of(" \"", found)) != cmdline.npos) && |
| (cmdline[found] == quote)) { |
| // unbalanced quote is ok |
| if ((found = cmdline.find(quote, found + 1)) == cmdline.npos) break; |
| ++found; |
| } |
| std::string piece; |
| auto source = cmdline.substr(base, found - base); |
| std::remove_copy(source.begin(), source.end(), |
| std::back_insert_iterator<std::string>(piece), quote); |
| auto equal_sign = piece.find('='); |
| if (equal_sign == piece.npos) { |
| if (!piece.empty()) { |
| // no difference between <key> and <key>= |
| result.emplace_back(std::move(piece), ""); |
| } |
| } else { |
| result.emplace_back(piece.substr(0, equal_sign), piece.substr(equal_sign + 1)); |
| } |
| if (found == cmdline.npos) break; |
| base = found + 1; |
| } |
| |
| return result; |
| } |
| |
| bool fs_mgr_get_boot_config_from_kernel(const std::string& cmdline, const std::string& android_key, |
| std::string* out_val) { |
| FS_MGR_CHECK(out_val != nullptr); |
| |
| const std::string cmdline_key("androidboot." + android_key); |
| for (const auto& [key, value] : fs_mgr_parse_boot_config(cmdline)) { |
| if (key == cmdline_key) { |
| *out_val = value; |
| return true; |
| } |
| } |
| |
| *out_val = ""; |
| return false; |
| } |
| |
| // Tries to get the given boot config value from kernel cmdline. |
| // Returns true if successfully found, false otherwise. |
| bool fs_mgr_get_boot_config_from_kernel_cmdline(const std::string& key, std::string* out_val) { |
| std::string cmdline; |
| if (!android::base::ReadFileToString("/proc/cmdline", &cmdline)) return false; |
| if (!cmdline.empty() && cmdline.back() == '\n') { |
| cmdline.pop_back(); |
| } |
| return fs_mgr_get_boot_config_from_kernel(cmdline, key, out_val); |
| } |
| |
| // Tries to get the boot config value in device tree, properties and |
| // kernel cmdline (in that order). Returns 'true' if successfully |
| // found, 'false' otherwise. |
| bool fs_mgr_get_boot_config(const std::string& key, std::string* out_val) { |
| FS_MGR_CHECK(out_val != nullptr); |
| |
| // firstly, check the device tree |
| if (is_dt_compatible()) { |
| std::string file_name = get_android_dt_dir() + "/" + key; |
| if (android::base::ReadFileToString(file_name, out_val)) { |
| if (!out_val->empty()) { |
| out_val->pop_back(); // Trims the trailing '\0' out. |
| return true; |
| } |
| } |
| } |
| |
| // next, check if we have "ro.boot" property already |
| *out_val = android::base::GetProperty("ro.boot." + key, ""); |
| if (!out_val->empty()) { |
| return true; |
| } |
| |
| // finally, fallback to kernel cmdline, properties may not be ready yet |
| if (fs_mgr_get_boot_config_from_kernel_cmdline(key, out_val)) { |
| return true; |
| } |
| |
| return false; |
| } |