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// Copyright (C) 2019 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 "utility.h"
#include <errno.h>
#include <time.h>
#include <iomanip>
#include <sstream>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/strings.h>
#include <fs_mgr/roots.h>
using android::dm::kSectorSize;
using android::fiemap::FiemapStatus;
using android::fs_mgr::EnsurePathMounted;
using android::fs_mgr::EnsurePathUnmounted;
using android::fs_mgr::Fstab;
using android::fs_mgr::GetEntryForPath;
using android::fs_mgr::MetadataBuilder;
using android::fs_mgr::Partition;
using android::fs_mgr::ReadDefaultFstab;
namespace android {
namespace snapshot {
void AutoDevice::Release() {
name_.clear();
}
AutoDeviceList::~AutoDeviceList() {
// Destroy devices in the reverse order because newer devices may have dependencies
// on older devices.
for (auto it = devices_.rbegin(); it != devices_.rend(); ++it) {
it->reset();
}
}
void AutoDeviceList::Release() {
for (auto&& p : devices_) {
p->Release();
}
}
AutoUnmapDevice::~AutoUnmapDevice() {
if (name_.empty()) return;
if (!dm_->DeleteDeviceIfExists(name_)) {
LOG(ERROR) << "Failed to auto unmap device " << name_;
}
}
AutoUnmapImage::~AutoUnmapImage() {
if (name_.empty()) return;
if (!images_->UnmapImageIfExists(name_)) {
LOG(ERROR) << "Failed to auto unmap cow image " << name_;
}
}
std::vector<Partition*> ListPartitionsWithSuffix(MetadataBuilder* builder,
const std::string& suffix) {
std::vector<Partition*> ret;
for (const auto& group : builder->ListGroups()) {
for (auto* partition : builder->ListPartitionsInGroup(group)) {
if (!base::EndsWith(partition->name(), suffix)) {
continue;
}
ret.push_back(partition);
}
}
return ret;
}
AutoDeleteSnapshot::~AutoDeleteSnapshot() {
if (!name_.empty() && !manager_->DeleteSnapshot(lock_, name_)) {
LOG(ERROR) << "Failed to auto delete snapshot " << name_;
}
}
Return InitializeCow(const std::string& device) {
// When the kernel creates a persistent dm-snapshot, it requires a CoW file
// to store the modifications. The kernel interface does not specify how
// the CoW is used, and there is no standard associated.
// By looking at the current implementation, the CoW file is treated as:
// - a _NEW_ snapshot if its first 32 bits are zero, so the newly created
// dm-snapshot device will look like a perfect copy of the origin device;
// - an _EXISTING_ snapshot if the first 32 bits are equal to a
// kernel-specified magic number and the CoW file metadata is set as valid,
// so it can be used to resume the last state of a snapshot device;
// - an _INVALID_ snapshot otherwise.
// To avoid zero-filling the whole CoW file when a new dm-snapshot is
// created, here we zero-fill only the first chunk to be compliant with
// lvm.
constexpr ssize_t kDmSnapZeroFillSize = kSectorSize * kSnapshotChunkSize;
std::vector<uint8_t> zeros(kDmSnapZeroFillSize, 0);
android::base::unique_fd fd(open(device.c_str(), O_WRONLY | O_BINARY));
if (fd < 0) {
PLOG(ERROR) << "Can't open COW device: " << device;
return Return(FiemapStatus::FromErrno(errno));
}
LOG(INFO) << "Zero-filling COW device: " << device;
if (!android::base::WriteFully(fd, zeros.data(), kDmSnapZeroFillSize)) {
PLOG(ERROR) << "Can't zero-fill COW device for " << device;
return Return(FiemapStatus::FromErrno(errno));
}
return Return::Ok();
}
std::unique_ptr<AutoUnmountDevice> AutoUnmountDevice::New(const std::string& path) {
Fstab fstab;
if (!ReadDefaultFstab(&fstab)) {
LOG(ERROR) << "Cannot read default fstab";
return nullptr;
}
if (GetEntryForPath(&fstab, path) == nullptr) {
LOG(INFO) << "EnsureMetadataMounted can't find entry for " << path << ", skipping";
return std::unique_ptr<AutoUnmountDevice>(new AutoUnmountDevice("", {}));
}
if (!EnsurePathMounted(&fstab, path)) {
LOG(ERROR) << "Cannot mount " << path;
return nullptr;
}
return std::unique_ptr<AutoUnmountDevice>(new AutoUnmountDevice(path, std::move(fstab)));
}
AutoUnmountDevice::~AutoUnmountDevice() {
if (name_.empty()) return;
if (!EnsurePathUnmounted(&fstab_, name_)) {
LOG(ERROR) << "Cannot unmount " << name_;
}
}
bool WriteStringToFileAtomic(const std::string& content, const std::string& path) {
std::string tmp_path = path + ".tmp";
if (!android::base::WriteStringToFile(content, tmp_path)) {
return false;
}
if (rename(tmp_path.c_str(), path.c_str()) == -1) {
PLOG(ERROR) << "rename failed from " << tmp_path << " to " << path;
return false;
}
return true;
}
std::ostream& operator<<(std::ostream& os, const Now&) {
struct tm now;
time_t t = time(nullptr);
localtime_r(&t, &now);
return os << std::put_time(&now, "%Y%m%d-%H%M%S");
}
} // namespace snapshot
} // namespace android
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