You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
83 lines
2.9 KiB
83 lines
2.9 KiB
/*
|
|
* 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 "ramdisk_utils.h"
|
|
|
|
#include <android-base/file.h>
|
|
#include <android-base/result.h>
|
|
#include <bootimg.h>
|
|
|
|
#include "cpio.h"
|
|
#include "lz4_legacy.h"
|
|
|
|
using android::base::ErrnoError;
|
|
using android::base::Error;
|
|
using android::base::ReadFullyAtOffset;
|
|
using android::base::WriteStringToFd;
|
|
|
|
namespace android {
|
|
|
|
namespace {
|
|
// Extract ramdisk from boot image / partition at |boot_path|.
|
|
// Return a temporary file storing the ramdisk section.
|
|
android::base::Result<std::unique_ptr<TemporaryFile>> ExtractRamdiskRaw(
|
|
std::string_view boot_path) {
|
|
android::base::unique_fd bootimg(
|
|
TEMP_FAILURE_RETRY(open(boot_path.data(), O_RDONLY)));
|
|
if (!bootimg.ok()) return ErrnoError() << "open(" << boot_path << ")";
|
|
boot_img_hdr_v3 hdr;
|
|
if (!ReadFullyAtOffset(bootimg.get(), &hdr, sizeof(hdr), 0))
|
|
return ErrnoError() << "read header";
|
|
if (0 != memcmp(hdr.magic, BOOT_MAGIC, BOOT_MAGIC_SIZE))
|
|
return Error() << "Boot magic mismatch";
|
|
|
|
if (hdr.header_version < 3)
|
|
return Error() << "Unsupported header version V" << hdr.header_version;
|
|
|
|
// See bootimg.h
|
|
auto kernel_size_bytes = (hdr.kernel_size + 4096 - 1) / 4096 * 4096;
|
|
auto ramdisk_offset = 4096 + kernel_size_bytes;
|
|
|
|
std::string ramdisk_content(hdr.ramdisk_size, '\0');
|
|
if (!ReadFullyAtOffset(bootimg.get(), ramdisk_content.data(),
|
|
hdr.ramdisk_size, ramdisk_offset))
|
|
return ErrnoError() << "read ramdisk section";
|
|
|
|
auto ramdisk_content_file = std::make_unique<TemporaryFile>();
|
|
if (!WriteStringToFd(ramdisk_content, ramdisk_content_file->fd))
|
|
return ErrnoError() << "write ramdisk section to file";
|
|
|
|
return ramdisk_content_file;
|
|
}
|
|
|
|
} // namespace
|
|
|
|
// From the boot image / partition, extract the ramdisk section, decompress it,
|
|
// and extract from the cpio archive.
|
|
android::base::Result<std::unique_ptr<TemporaryDir>> ExtractRamdiskToDirectory(
|
|
std::string_view boot_path) {
|
|
auto raw_ramdisk_file = ExtractRamdiskRaw(boot_path);
|
|
if (!raw_ramdisk_file.ok()) return raw_ramdisk_file.error();
|
|
|
|
TemporaryFile decompressed;
|
|
auto decompress_res = android::Lz4DecompressLegacy((*raw_ramdisk_file)->path,
|
|
decompressed.path);
|
|
if (!decompress_res.ok()) return decompress_res.error();
|
|
|
|
return android::CpioExtract(decompressed.path);
|
|
}
|
|
|
|
} // namespace android
|