/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <algorithm>
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#include <iterator>
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#include <string>
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#include <vector>
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#include <android-base/file.h>
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#include <android-base/stringprintf.h>
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#include <android-base/strings.h>
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#include <android-base/properties.h>
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#include "fs_mgr_priv.h"
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std::vector<std::pair<std::string, std::string>> fs_mgr_parse_boot_config(const std::string& cmdline) {
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static constexpr char quote = '"';
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std::vector<std::pair<std::string, std::string>> result;
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size_t base = 0;
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while (true) {
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// skip quoted spans
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auto found = base;
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while (((found = cmdline.find_first_of(" \"", found)) != cmdline.npos) &&
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(cmdline[found] == quote)) {
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// unbalanced quote is ok
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if ((found = cmdline.find(quote, found + 1)) == cmdline.npos) break;
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++found;
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}
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std::string piece;
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auto source = cmdline.substr(base, found - base);
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std::remove_copy(source.begin(), source.end(),
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std::back_insert_iterator<std::string>(piece), quote);
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auto equal_sign = piece.find('=');
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if (equal_sign == piece.npos) {
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if (!piece.empty()) {
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// no difference between <key> and <key>=
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result.emplace_back(std::move(piece), "");
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}
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} else {
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result.emplace_back(piece.substr(0, equal_sign), piece.substr(equal_sign + 1));
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}
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if (found == cmdline.npos) break;
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base = found + 1;
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}
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return result;
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}
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bool fs_mgr_get_boot_config_from_kernel(const std::string& cmdline, const std::string& android_key,
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std::string* out_val) {
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FS_MGR_CHECK(out_val != nullptr);
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const std::string cmdline_key("androidboot." + android_key);
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for (const auto& [key, value] : fs_mgr_parse_boot_config(cmdline)) {
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if (key == cmdline_key) {
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*out_val = value;
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return true;
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}
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}
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*out_val = "";
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return false;
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}
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// Tries to get the given boot config value from kernel cmdline.
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// Returns true if successfully found, false otherwise.
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bool fs_mgr_get_boot_config_from_kernel_cmdline(const std::string& key, std::string* out_val) {
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std::string cmdline;
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if (!android::base::ReadFileToString("/proc/cmdline", &cmdline)) return false;
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if (!cmdline.empty() && cmdline.back() == '\n') {
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cmdline.pop_back();
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}
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return fs_mgr_get_boot_config_from_kernel(cmdline, key, out_val);
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}
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// Tries to get the boot config value in device tree, properties and
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// kernel cmdline (in that order). Returns 'true' if successfully
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// found, 'false' otherwise.
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bool fs_mgr_get_boot_config(const std::string& key, std::string* out_val) {
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FS_MGR_CHECK(out_val != nullptr);
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// firstly, check the device tree
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if (is_dt_compatible()) {
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std::string file_name = get_android_dt_dir() + "/" + key;
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if (android::base::ReadFileToString(file_name, out_val)) {
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if (!out_val->empty()) {
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out_val->pop_back(); // Trims the trailing '\0' out.
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return true;
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}
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}
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}
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// next, check if we have "ro.boot" property already
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*out_val = android::base::GetProperty("ro.boot." + key, "");
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if (!out_val->empty()) {
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return true;
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}
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// finally, fallback to kernel cmdline, properties may not be ready yet
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if (fs_mgr_get_boot_config_from_kernel_cmdline(key, out_val)) {
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return true;
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}
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return false;
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}
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