66270a21df
Now that we're treating storage as a runtime permission, we need to grant read/write access without killing the app. This is really tricky, since we had been using GIDs for access control, and they're set in stone once Zygote drops privileges. The only thing left that can change dynamically is the filesystem itself, so let's do that. This means changing the FUSE daemon to present itself as three different views: /mnt/runtime_default/foo - view for apps with no access /mnt/runtime_read/foo - view for apps with read access /mnt/runtime_write/foo - view for apps with write access There is still a single location for all the backing files, and filesystem permissions are derived the same way for each view, but the file modes are masked off differently for each mountpoint. During Zygote fork, it wires up the appropriate storage access into an isolated mount namespace based on the current app permissions. When the app is granted permissions dynamically at runtime, the system asks vold to jump into the existing mount namespace and bind mount the newly granted access model into place. Bug: 21858077 Change-Id: Iade538e4bc7af979fe20095f74416e8a0f165a4a
256 lines
6.4 KiB
C++
256 lines
6.4 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "Utils.h"
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#include "VolumeBase.h"
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#include "VolumeManager.h"
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#include "ResponseCode.h"
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#include <base/stringprintf.h>
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#include <base/logging.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <sys/mount.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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using android::base::StringPrintf;
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#define DEBUG 1
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namespace android {
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namespace vold {
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VolumeBase::VolumeBase(Type type) :
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mType(type), mMountFlags(0), mMountUserId(-1), mCreated(false), mState(
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State::kUnmounted), mSilent(false) {
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}
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VolumeBase::~VolumeBase() {
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CHECK(!mCreated);
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}
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void VolumeBase::setState(State state) {
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mState = state;
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notifyEvent(ResponseCode::VolumeStateChanged, StringPrintf("%d", mState));
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}
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status_t VolumeBase::setDiskId(const std::string& diskId) {
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if (mCreated) {
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LOG(WARNING) << getId() << " diskId change requires destroyed";
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return -EBUSY;
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}
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mDiskId = diskId;
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return OK;
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}
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status_t VolumeBase::setPartGuid(const std::string& partGuid) {
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if (mCreated) {
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LOG(WARNING) << getId() << " partGuid change requires destroyed";
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return -EBUSY;
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}
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mPartGuid = partGuid;
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return OK;
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}
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status_t VolumeBase::setMountFlags(int mountFlags) {
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if ((mState != State::kUnmounted) && (mState != State::kUnmountable)) {
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LOG(WARNING) << getId() << " flags change requires state unmounted or unmountable";
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return -EBUSY;
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}
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mMountFlags = mountFlags;
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return OK;
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}
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status_t VolumeBase::setMountUserId(userid_t mountUserId) {
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if ((mState != State::kUnmounted) && (mState != State::kUnmountable)) {
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LOG(WARNING) << getId() << " user change requires state unmounted or unmountable";
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return -EBUSY;
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}
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mMountUserId = mountUserId;
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return OK;
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}
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status_t VolumeBase::setSilent(bool silent) {
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if (mCreated) {
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LOG(WARNING) << getId() << " silence change requires destroyed";
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return -EBUSY;
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}
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mSilent = silent;
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return OK;
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}
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status_t VolumeBase::setId(const std::string& id) {
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if (mCreated) {
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LOG(WARNING) << getId() << " id change requires not created";
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return -EBUSY;
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}
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mId = id;
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return OK;
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}
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status_t VolumeBase::setPath(const std::string& path) {
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if (mState != State::kChecking) {
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LOG(WARNING) << getId() << " path change requires state checking";
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return -EBUSY;
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}
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mPath = path;
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notifyEvent(ResponseCode::VolumePathChanged, mPath);
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return OK;
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}
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status_t VolumeBase::setInternalPath(const std::string& internalPath) {
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if (mState != State::kChecking) {
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LOG(WARNING) << getId() << " internal path change requires state checking";
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return -EBUSY;
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}
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mInternalPath = internalPath;
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notifyEvent(ResponseCode::VolumeInternalPathChanged, mInternalPath);
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return OK;
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}
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void VolumeBase::notifyEvent(int event) {
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if (mSilent) return;
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VolumeManager::Instance()->getBroadcaster()->sendBroadcast(event,
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getId().c_str(), false);
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}
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void VolumeBase::notifyEvent(int event, const std::string& value) {
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if (mSilent) return;
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VolumeManager::Instance()->getBroadcaster()->sendBroadcast(event,
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StringPrintf("%s %s", getId().c_str(), value.c_str()).c_str(), false);
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}
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void VolumeBase::addVolume(const std::shared_ptr<VolumeBase>& volume) {
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mVolumes.push_back(volume);
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}
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void VolumeBase::removeVolume(const std::shared_ptr<VolumeBase>& volume) {
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mVolumes.remove(volume);
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}
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std::shared_ptr<VolumeBase> VolumeBase::findVolume(const std::string& id) {
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for (auto vol : mVolumes) {
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if (vol->getId() == id) {
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return vol;
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}
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}
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return nullptr;
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}
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status_t VolumeBase::create() {
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CHECK(!mCreated);
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mCreated = true;
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status_t res = doCreate();
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notifyEvent(ResponseCode::VolumeCreated,
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StringPrintf("%d \"%s\" \"%s\"", mType, mDiskId.c_str(), mPartGuid.c_str()));
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setState(State::kUnmounted);
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return res;
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}
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status_t VolumeBase::doCreate() {
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return OK;
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}
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status_t VolumeBase::destroy() {
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CHECK(mCreated);
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if (mState == State::kMounted) {
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unmount();
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setState(State::kBadRemoval);
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} else {
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setState(State::kRemoved);
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}
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notifyEvent(ResponseCode::VolumeDestroyed);
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status_t res = doDestroy();
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mCreated = false;
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return res;
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}
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status_t VolumeBase::doDestroy() {
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return OK;
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}
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status_t VolumeBase::mount() {
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if ((mState != State::kUnmounted) && (mState != State::kUnmountable)) {
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LOG(WARNING) << getId() << " mount requires state unmounted or unmountable";
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return -EBUSY;
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}
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setState(State::kChecking);
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status_t res = doMount();
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if (res == OK) {
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setState(State::kMounted);
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} else {
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setState(State::kUnmountable);
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}
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return res;
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}
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status_t VolumeBase::unmount() {
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if (mState != State::kMounted) {
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LOG(WARNING) << getId() << " unmount requires state mounted";
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return -EBUSY;
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}
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setState(State::kEjecting);
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for (auto vol : mVolumes) {
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if (vol->destroy()) {
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LOG(WARNING) << getId() << " failed to destroy " << vol->getId()
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<< " stacked above";
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}
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}
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mVolumes.clear();
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status_t res = doUnmount();
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setState(State::kUnmounted);
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return res;
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}
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status_t VolumeBase::format(const std::string& fsType) {
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if (mState == State::kMounted) {
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unmount();
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}
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if ((mState != State::kUnmounted) && (mState != State::kUnmountable)) {
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LOG(WARNING) << getId() << " format requires state unmounted or unmountable";
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return -EBUSY;
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}
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setState(State::kFormatting);
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status_t res = doFormat(fsType);
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setState(State::kUnmounted);
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return res;
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}
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status_t VolumeBase::doFormat(const std::string& fsType) {
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return -ENOTSUP;
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}
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} // namespace vold
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} // namespace android
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