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/*
* Copyright (C) 2021 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 "cpio.h"
#include <sys/types.h>
#include <sys/wait.h>
#include <vector>
#include <android-base/logging.h>
#include <android-base/strings.h>
using android::base::ErrnoError;
using android::base::Error;
using android::base::Join;
namespace android {
namespace {
std::vector<char*> ToCStringArray(std::vector<std::string>* args) {
std::vector<char*> ret;
ret.reserve(args->size() + 1);
for (auto& arg : *args) {
ret.push_back(arg.data());
}
ret.push_back(nullptr);
return ret;
}
// Wrapper of fork() / execvp() / wait() paradigm. Child process chdir() into
// the directory before execv()
android::base::Result<void> Exec(std::vector<std::string>* args,
std::string_view working_directory) {
pid_t pid = fork();
if (pid == -1)
return ErrnoError() << "Unable to execute `" << Join(*args, " ")
<< "`: failed to fork";
if (pid == 0) {
// child process
CHECK(0 == chdir(working_directory.data())) << strerror(errno);
// execvp needs char*, so copy the strings to heap.
auto c_args = ToCStringArray(args);
(void)close(STDIN_FILENO);
(void)execvp(c_args[0], c_args.data());
// execvp only returns on error.
PLOG(FATAL) << "Unable to execute `" << Join(*args, " ")
<< "`: execvp returns";
}
// parent process
int status;
if (pid != waitpid(pid, &status, 0))
return ErrnoError() << "Unable to execute `" << Join(*args, " ")
<< "`; failed to waitpid(" << pid << ")";
if (!WIFEXITED(status))
return Error() << "Unable to execute `" << Join(*args, " ")
<< "`: not exited normally";
if (0 != WEXITSTATUS(status))
return Error() << "Unable to execute `" << Join(*args, " ")
<< "`: exit status " << WEXITSTATUS(status);
return {};
}
} // namespace
// Extract CPIO archive at |archive_path| to a temporary directory.
android::base::Result<std::unique_ptr<TemporaryDir>> CpioExtract(
std::string_view archive_path) {
std::vector<std::string> args{"cpio", "-i", "-F", archive_path.data()};
auto extracted_ramdisk = std::make_unique<TemporaryDir>();
auto res = Exec(&args, extracted_ramdisk->path);
if (!res.ok()) return res.error();
return extracted_ramdisk;
}
} // namespace android