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//
// Copyright (C) 2018 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 "update_engine/payload_consumer/mount_history.h"
#include <inttypes.h>
#include <string>
#include <vector>
#include <base/logging.h>
#include <base/time/time.h>
#include "update_engine/common/utils.h"
namespace chromeos_update_engine {
void LogMountHistory(const FileDescriptorPtr blockdevice_fd) {
static constexpr ssize_t kBlockSize = 4096;
if (blockdevice_fd == nullptr) {
return;
}
brillo::Blob block0_buffer(kBlockSize);
ssize_t bytes_read;
if (!utils::ReadAll(
blockdevice_fd, block0_buffer.data(), kBlockSize, 0, &bytes_read)) {
LOG(WARNING) << "PReadAll failed";
return;
}
if (bytes_read != kBlockSize) {
LOG(WARNING) << "Could not read an entire block";
return;
}
// https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout
// Super block starts from block 0, offset 0x400
// 0x2C: len32 Mount time
// 0x30: len32 Write time
// 0x34: len16 Number of mounts since the last fsck
// 0x38: len16 Magic signature 0xEF53
// 0x40: len32 Time of last check
// 0x108: len32 When the filesystem was created
time_t mount_time =
*reinterpret_cast<uint32_t*>(&block0_buffer[0x400 + 0x2C]);
time_t write_time =
*reinterpret_cast<uint32_t*>(&block0_buffer[0x400 + 0x30]);
uint16_t mount_count =
*reinterpret_cast<uint16_t*>(&block0_buffer[0x400 + 0x34]);
uint16_t magic = *reinterpret_cast<uint16_t*>(&block0_buffer[0x400 + 0x38]);
time_t check_time =
*reinterpret_cast<uint32_t*>(&block0_buffer[0x400 + 0x40]);
time_t created_time =
*reinterpret_cast<uint32_t*>(&block0_buffer[0x400 + 0x108]);
if (magic == 0xEF53) {
// Timestamps can be updated by fsck without updating mount count,
// log if any timestamp differ
if (! (write_time == created_time && check_time == created_time)) {
LOG(WARNING) << "Device have been modified after being created. "
<< "Filesystem created on "
<< base::Time::FromTimeT(created_time) << ", "
<< "last written on "
<< base::Time::FromTimeT(write_time) << ", "
<< "last checked on "
<< base::Time::FromTimeT(check_time) << ".";
}
if (mount_count > 0) {
LOG(WARNING) << "Device was remounted R/W " << mount_count << " times. "
<< "Last remount happened on "
<< base::Time::FromTimeT(mount_time) << ".";
}
}
}
} // namespace chromeos_update_engine
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