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/*
* 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;
}
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