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/*
* Copyright (C) 2013 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.
*/
package com.android.externalstorage;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.app.usage.StorageStatsManager;
import android.content.ContentResolver;
import android.content.UriPermission;
import android.database.Cursor;
import android.database.MatrixCursor;
import android.database.MatrixCursor.RowBuilder;
import android.net.Uri;
import android.os.Binder;
import android.os.Bundle;
import android.os.Environment;
import android.os.IBinder;
import android.os.UserHandle;
import android.os.UserManager;
import android.os.storage.DiskInfo;
import android.os.storage.StorageEventListener;
import android.os.storage.StorageManager;
import android.os.storage.VolumeInfo;
import android.provider.DocumentsContract;
import android.provider.DocumentsContract.Document;
import android.provider.DocumentsContract.Path;
import android.provider.DocumentsContract.Root;
import android.provider.Settings;
import android.system.ErrnoException;
import android.system.Os;
import android.system.OsConstants;
import android.text.TextUtils;
import android.util.ArrayMap;
import android.util.DebugUtils;
import android.util.Log;
import android.util.Pair;
import com.android.internal.annotations.GuardedBy;
import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.content.FileSystemProvider;
import com.android.internal.util.IndentingPrintWriter;
import java.io.File;
import java.io.FileDescriptor;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import java.util.UUID;
public class ExternalStorageProvider extends FileSystemProvider {
private static final String TAG = "ExternalStorage";
private static final boolean DEBUG = false;
public static final String AUTHORITY = DocumentsContract.EXTERNAL_STORAGE_PROVIDER_AUTHORITY;
private static final Uri BASE_URI =
new Uri.Builder().scheme(ContentResolver.SCHEME_CONTENT).authority(AUTHORITY).build();
// docId format: root:path/to/file
private static final String[] DEFAULT_ROOT_PROJECTION = new String[] {
Root.COLUMN_ROOT_ID, Root.COLUMN_FLAGS, Root.COLUMN_ICON, Root.COLUMN_TITLE,
Root.COLUMN_DOCUMENT_ID, Root.COLUMN_AVAILABLE_BYTES, Root.COLUMN_QUERY_ARGS
};
private static final String[] DEFAULT_DOCUMENT_PROJECTION = new String[] {
Document.COLUMN_DOCUMENT_ID, Document.COLUMN_MIME_TYPE, Document.COLUMN_DISPLAY_NAME,
Document.COLUMN_LAST_MODIFIED, Document.COLUMN_FLAGS, Document.COLUMN_SIZE,
};
private static class RootInfo {
public String rootId;
public String volumeId;
public UUID storageUuid;
public int flags;
public String title;
public String docId;
public File visiblePath;
public File path;
// TODO (b/157033915): Make getFreeBytes() faster
public boolean reportAvailableBytes = false;
}
private static final String ROOT_ID_PRIMARY_EMULATED =
DocumentsContract.EXTERNAL_STORAGE_PRIMARY_EMULATED_ROOT_ID;
private static final String GET_DOCUMENT_URI_CALL = "get_document_uri";
private static final String GET_MEDIA_URI_CALL = "get_media_uri";
private StorageManager mStorageManager;
private UserManager mUserManager;
private final Object mRootsLock = new Object();
@GuardedBy("mRootsLock")
private ArrayMap<String, RootInfo> mRoots = new ArrayMap<>();
@Override
public boolean onCreate() {
super.onCreate(DEFAULT_DOCUMENT_PROJECTION);
mStorageManager = getContext().getSystemService(StorageManager.class);
mUserManager = getContext().getSystemService(UserManager.class);
updateVolumes();
mStorageManager.registerListener(new StorageEventListener() {
@Override
public void onVolumeStateChanged(VolumeInfo vol, int oldState, int newState) {
updateVolumes();
}
});
return true;
}
private void enforceShellRestrictions() {
if (UserHandle.getCallingAppId() == android.os.Process.SHELL_UID
&& mUserManager.hasUserRestriction(UserManager.DISALLOW_USB_FILE_TRANSFER)) {
throw new SecurityException(
"Shell user cannot access files for user " + UserHandle.myUserId());
}
}
@Override
protected int enforceReadPermissionInner(Uri uri, String callingPkg,
@Nullable String featureId, IBinder callerToken) throws SecurityException {
enforceShellRestrictions();
return super.enforceReadPermissionInner(uri, callingPkg, featureId, callerToken);
}
@Override
protected int enforceWritePermissionInner(Uri uri, String callingPkg,
@Nullable String featureId, IBinder callerToken) throws SecurityException {
enforceShellRestrictions();
return super.enforceWritePermissionInner(uri, callingPkg, featureId, callerToken);
}
public void updateVolumes() {
synchronized (mRootsLock) {
updateVolumesLocked();
}
}
@GuardedBy("mRootsLock")
private void updateVolumesLocked() {
mRoots.clear();
final int userId = UserHandle.myUserId();
final List<VolumeInfo> volumes = mStorageManager.getVolumes();
for (VolumeInfo volume : volumes) {
if (!volume.isMountedReadable() || volume.getMountUserId() != userId) continue;
final String rootId;
final String title;
final UUID storageUuid;
if (volume.getType() == VolumeInfo.TYPE_EMULATED) {
// We currently only support a single emulated volume per user mounted at
// a time, and it's always considered the primary
if (DEBUG) Log.d(TAG, "Found primary volume: " + volume);
rootId = ROOT_ID_PRIMARY_EMULATED;
if (volume.isPrimaryEmulatedForUser(userId)) {
// This is basically the user's primary device storage.
// Use device name for the volume since this is likely same thing
// the user sees when they mount their phone on another device.
String deviceName = Settings.Global.getString(
getContext().getContentResolver(), Settings.Global.DEVICE_NAME);
// Device name should always be set. In case it isn't, though,
// fall back to a localized "Internal Storage" string.
title = !TextUtils.isEmpty(deviceName)
? deviceName
: getContext().getString(R.string.root_internal_storage);
storageUuid = StorageManager.UUID_DEFAULT;
} else {
// This should cover all other storage devices, like an SD card
// or USB OTG drive plugged in. Using getBestVolumeDescription()
// will give us a nice string like "Samsung SD card" or "SanDisk USB drive"
final VolumeInfo privateVol = mStorageManager.findPrivateForEmulated(volume);
title = mStorageManager.getBestVolumeDescription(privateVol);
storageUuid = StorageManager.convert(privateVol.fsUuid);
}
} else if (volume.getType() == VolumeInfo.TYPE_PUBLIC
|| volume.getType() == VolumeInfo.TYPE_STUB) {
rootId = volume.getFsUuid();
title = mStorageManager.getBestVolumeDescription(volume);
storageUuid = null;
} else {
// Unsupported volume; ignore
continue;
}
if (TextUtils.isEmpty(rootId)) {
Log.d(TAG, "Missing UUID for " + volume.getId() + "; skipping");
continue;
}
if (mRoots.containsKey(rootId)) {
Log.w(TAG, "Duplicate UUID " + rootId + " for " + volume.getId() + "; skipping");
continue;
}
final RootInfo root = new RootInfo();
mRoots.put(rootId, root);
root.rootId = rootId;
root.volumeId = volume.id;
root.storageUuid = storageUuid;
root.flags = Root.FLAG_LOCAL_ONLY
| Root.FLAG_SUPPORTS_SEARCH
| Root.FLAG_SUPPORTS_IS_CHILD;
final DiskInfo disk = volume.getDisk();
if (DEBUG) Log.d(TAG, "Disk for root " + rootId + " is " + disk);
if (disk != null && disk.isSd()) {
root.flags |= Root.FLAG_REMOVABLE_SD;
} else if (disk != null && disk.isUsb()) {
root.flags |= Root.FLAG_REMOVABLE_USB;
}
if (volume.getType() != VolumeInfo.TYPE_EMULATED) {
root.flags |= Root.FLAG_SUPPORTS_EJECT;
}
if (volume.isPrimary()) {
root.flags |= Root.FLAG_ADVANCED;
}
// Dunno when this would NOT be the case, but never hurts to be correct.
if (volume.isMountedWritable()) {
root.flags |= Root.FLAG_SUPPORTS_CREATE;
}
root.title = title;
if (volume.getType() == VolumeInfo.TYPE_PUBLIC) {
root.flags |= Root.FLAG_HAS_SETTINGS;
}
if (volume.isVisibleForRead(userId)) {
root.visiblePath = volume.getPathForUser(userId);
} else {
root.visiblePath = null;
}
root.path = volume.getInternalPathForUser(userId);
try {
root.docId = getDocIdForFile(root.path);
} catch (FileNotFoundException e) {
throw new IllegalStateException(e);
}
}
Log.d(TAG, "After updating volumes, found " + mRoots.size() + " active roots");
// Note this affects content://com.android.externalstorage.documents/root/39BD-07C5
// as well as content://com.android.externalstorage.documents/document/*/children,
// so just notify on content://com.android.externalstorage.documents/.
getContext().getContentResolver().notifyChange(BASE_URI, null, false);
}
private static String[] resolveRootProjection(String[] projection) {
return projection != null ? projection : DEFAULT_ROOT_PROJECTION;
}
@Override
public Cursor queryChildDocumentsForManage(
String parentDocId, String[] projection, String sortOrder)
throws FileNotFoundException {
return queryChildDocumentsShowAll(parentDocId, projection, sortOrder);
}
/**
* Check that the directory is the root of storage or blocked file from tree.
*
* @param docId the docId of the directory to be checked
* @return true, should be blocked from tree. Otherwise, false.
*/
@Override
protected boolean shouldBlockFromTree(@NonNull String docId) {
try {
final File dir = getFileForDocId(docId, false /* visible */);
// the file is null or it is not a directory
if (dir == null || !dir.isDirectory()) {
return false;
}
// Allow all directories on USB, including the root.
try {
RootInfo rootInfo = getRootFromDocId(docId);
if ((rootInfo.flags & Root.FLAG_REMOVABLE_USB) == Root.FLAG_REMOVABLE_USB) {
return false;
}
} catch (FileNotFoundException e) {
Log.e(TAG, "Failed to determine rootInfo for docId");
}
final String path = getPathFromDocId(docId);
// Block the root of the storage
if (path.isEmpty()) {
return true;
}
// Block Download folder from tree
if (TextUtils.equals(Environment.DIRECTORY_DOWNLOADS.toLowerCase(),
path.toLowerCase())) {
return true;
}
return false;
} catch (IOException e) {
throw new IllegalArgumentException(
"Failed to determine if " + docId + " should block from tree " + ": " + e);
}
}
@Override
protected String getDocIdForFile(File file) throws FileNotFoundException {
return getDocIdForFileMaybeCreate(file, false);
}
private String getDocIdForFileMaybeCreate(File file, boolean createNewDir)
throws FileNotFoundException {
String path = file.getAbsolutePath();
// Find the most-specific root path
boolean visiblePath = false;
RootInfo mostSpecificRoot = getMostSpecificRootForPath(path, false);
if (mostSpecificRoot == null) {
// Try visible path if no internal path matches. MediaStore uses visible paths.
visiblePath = true;
mostSpecificRoot = getMostSpecificRootForPath(path, true);
}
if (mostSpecificRoot == null) {
throw new FileNotFoundException("Failed to find root that contains " + path);
}
// Start at first char of path under root
final String rootPath = visiblePath
? mostSpecificRoot.visiblePath.getAbsolutePath()
: mostSpecificRoot.path.getAbsolutePath();
if (rootPath.equals(path)) {
path = "";
} else if (rootPath.endsWith("/")) {
path = path.substring(rootPath.length());
} else {
path = path.substring(rootPath.length() + 1);
}
if (!file.exists() && createNewDir) {
Log.i(TAG, "Creating new directory " + file);
if (!file.mkdir()) {
Log.e(TAG, "Could not create directory " + file);
}
}
return mostSpecificRoot.rootId + ':' + path;
}
private RootInfo getMostSpecificRootForPath(String path, boolean visible) {
// Find the most-specific root path
RootInfo mostSpecificRoot = null;
String mostSpecificPath = null;
synchronized (mRootsLock) {
for (int i = 0; i < mRoots.size(); i++) {
final RootInfo root = mRoots.valueAt(i);
final File rootFile = visible ? root.visiblePath : root.path;
if (rootFile != null) {
final String rootPath = rootFile.getAbsolutePath();
if (path.startsWith(rootPath) && (mostSpecificPath == null
|| rootPath.length() > mostSpecificPath.length())) {
mostSpecificRoot = root;
mostSpecificPath = rootPath;
}
}
}
}
return mostSpecificRoot;
}
@Override
protected File getFileForDocId(String docId, boolean visible) throws FileNotFoundException {
return getFileForDocId(docId, visible, true);
}
private File getFileForDocId(String docId, boolean visible, boolean mustExist)
throws FileNotFoundException {
RootInfo root = getRootFromDocId(docId);
return buildFile(root, docId, visible, mustExist);
}
private Pair<RootInfo, File> resolveDocId(String docId, boolean visible)
throws FileNotFoundException {
RootInfo root = getRootFromDocId(docId);
return Pair.create(root, buildFile(root, docId, visible, true));
}
@VisibleForTesting
static String getPathFromDocId(String docId) {
final int splitIndex = docId.indexOf(':', 1);
final String path = docId.substring(splitIndex + 1);
if (path.isEmpty()) {
return path;
}
// remove trailing "/"
if (path.charAt(path.length() - 1) == '/') {
return path.substring(0, path.length() - 1);
} else {
return path;
}
}
private RootInfo getRootFromDocId(String docId) throws FileNotFoundException {
final int splitIndex = docId.indexOf(':', 1);
final String tag = docId.substring(0, splitIndex);
RootInfo root;
synchronized (mRootsLock) {
root = mRoots.get(tag);
}
if (root == null) {
throw new FileNotFoundException("No root for " + tag);
}
return root;
}
private File buildFile(RootInfo root, String docId, boolean visible, boolean mustExist)
throws FileNotFoundException {
final int splitIndex = docId.indexOf(':', 1);
final String path = docId.substring(splitIndex + 1);
File target = root.visiblePath != null ? root.visiblePath : root.path;
if (target == null) {
return null;
}
if (!target.exists()) {
target.mkdirs();
}
target = new File(target, path);
if (mustExist && !target.exists()) {
throw new FileNotFoundException("Missing file for " + docId + " at " + target);
}
return target;
}
@Override
protected Uri buildNotificationUri(String docId) {
return DocumentsContract.buildChildDocumentsUri(AUTHORITY, docId);
}
@Override
protected void onDocIdChanged(String docId) {
try {
// Touch the visible path to ensure that any sdcardfs caches have
// been updated to reflect underlying changes on disk.
final File visiblePath = getFileForDocId(docId, true, false);
if (visiblePath != null) {
Os.access(visiblePath.getAbsolutePath(), OsConstants.F_OK);
}
} catch (FileNotFoundException | ErrnoException ignored) {
}
}
@Override
public Cursor queryRoots(String[] projection) throws FileNotFoundException {
final MatrixCursor result = new MatrixCursor(resolveRootProjection(projection));
synchronized (mRootsLock) {
for (RootInfo root : mRoots.values()) {
final RowBuilder row = result.newRow();
row.add(Root.COLUMN_ROOT_ID, root.rootId);
row.add(Root.COLUMN_FLAGS, root.flags);
row.add(Root.COLUMN_TITLE, root.title);
row.add(Root.COLUMN_DOCUMENT_ID, root.docId);
row.add(Root.COLUMN_QUERY_ARGS, SUPPORTED_QUERY_ARGS);
long availableBytes = -1;
if (root.reportAvailableBytes) {
if (root.storageUuid != null) {
try {
availableBytes = getContext()
.getSystemService(StorageStatsManager.class)
.getFreeBytes(root.storageUuid);
} catch (IOException e) {
Log.w(TAG, e);
}
} else {
availableBytes = root.path.getUsableSpace();
}
}
row.add(Root.COLUMN_AVAILABLE_BYTES, availableBytes);
}
}
return result;
}
@Override
public Path findDocumentPath(@Nullable String parentDocId, String childDocId)
throws FileNotFoundException {
final Pair<RootInfo, File> resolvedDocId = resolveDocId(childDocId, false);
final RootInfo root = resolvedDocId.first;
File child = resolvedDocId.second;
final File rootFile = root.visiblePath != null ? root.visiblePath
: root.path;
final File parent = TextUtils.isEmpty(parentDocId)
? rootFile
: getFileForDocId(parentDocId);
return new Path(parentDocId == null ? root.rootId : null, findDocumentPath(parent, child));
}
private Uri getDocumentUri(String path, List<UriPermission> accessUriPermissions)
throws FileNotFoundException {
File doc = new File(path);
final String docId = getDocIdForFile(doc);
UriPermission docUriPermission = null;
UriPermission treeUriPermission = null;
for (UriPermission uriPermission : accessUriPermissions) {
final Uri uri = uriPermission.getUri();
if (AUTHORITY.equals(uri.getAuthority())) {
boolean matchesRequestedDoc = false;
if (DocumentsContract.isTreeUri(uri)) {
final String parentDocId = DocumentsContract.getTreeDocumentId(uri);
if (isChildDocument(parentDocId, docId)) {
treeUriPermission = uriPermission;
matchesRequestedDoc = true;
}
} else {
final String candidateDocId = DocumentsContract.getDocumentId(uri);
if (Objects.equals(docId, candidateDocId)) {
docUriPermission = uriPermission;
matchesRequestedDoc = true;
}
}
if (matchesRequestedDoc && allowsBothReadAndWrite(uriPermission)) {
// This URI permission provides everything an app can get, no need to
// further check any other granted URI.
break;
}
}
}
// Full permission URI first.
if (allowsBothReadAndWrite(treeUriPermission)) {
return DocumentsContract.buildDocumentUriUsingTree(treeUriPermission.getUri(), docId);
}
if (allowsBothReadAndWrite(docUriPermission)) {
return docUriPermission.getUri();
}
// Then partial permission URI.
if (treeUriPermission != null) {
return DocumentsContract.buildDocumentUriUsingTree(treeUriPermission.getUri(), docId);
}
if (docUriPermission != null) {
return docUriPermission.getUri();
}
throw new SecurityException("The app is not given any access to the document under path " +
path + " with permissions granted in " + accessUriPermissions);
}
private static boolean allowsBothReadAndWrite(UriPermission permission) {
return permission != null
&& permission.isReadPermission()
&& permission.isWritePermission();
}
@Override
public Cursor querySearchDocuments(String rootId, String[] projection, Bundle queryArgs)
throws FileNotFoundException {
final File parent;
synchronized (mRootsLock) {
RootInfo root = mRoots.get(rootId);
parent = root.visiblePath != null ? root.visiblePath
: root.path;
}
return querySearchDocuments(parent, projection, Collections.emptySet(), queryArgs);
}
@Override
public void ejectRoot(String rootId) {
final long token = Binder.clearCallingIdentity();
RootInfo root = mRoots.get(rootId);
if (root != null) {
try {
mStorageManager.unmount(root.volumeId);
} catch (RuntimeException e) {
throw new IllegalStateException(e);
} finally {
Binder.restoreCallingIdentity(token);
}
}
}
@Override
public void dump(FileDescriptor fd, PrintWriter writer, String[] args) {
final IndentingPrintWriter pw = new IndentingPrintWriter(writer, " ", 160);
synchronized (mRootsLock) {
for (int i = 0; i < mRoots.size(); i++) {
final RootInfo root = mRoots.valueAt(i);
pw.println("Root{" + root.rootId + "}:");
pw.increaseIndent();
pw.printPair("flags", DebugUtils.flagsToString(Root.class, "FLAG_", root.flags));
pw.println();
pw.printPair("title", root.title);
pw.printPair("docId", root.docId);
pw.println();
pw.printPair("path", root.path);
pw.printPair("visiblePath", root.visiblePath);
pw.decreaseIndent();
pw.println();
}
}
}
@Override
public Bundle call(String method, String arg, Bundle extras) {
Bundle bundle = super.call(method, arg, extras);
if (bundle == null && !TextUtils.isEmpty(method)) {
switch (method) {
case "getDocIdForFileCreateNewDir": {
getContext().enforceCallingPermission(
android.Manifest.permission.MANAGE_DOCUMENTS, null);
if (TextUtils.isEmpty(arg)) {
return null;
}
try {
final String docId = getDocIdForFileMaybeCreate(new File(arg), true);
bundle = new Bundle();
bundle.putString("DOC_ID", docId);
} catch (FileNotFoundException e) {
Log.w(TAG, "file '" + arg + "' not found");
return null;
}
break;
}
case GET_DOCUMENT_URI_CALL: {
// All callers must go through MediaProvider
getContext().enforceCallingPermission(
android.Manifest.permission.WRITE_MEDIA_STORAGE, TAG);
final Uri fileUri = extras.getParcelable(DocumentsContract.EXTRA_URI);
final List<UriPermission> accessUriPermissions = extras
.getParcelableArrayList(DocumentsContract.EXTRA_URI_PERMISSIONS);
final String path = fileUri.getPath();
try {
final Bundle out = new Bundle();
final Uri uri = getDocumentUri(path, accessUriPermissions);
out.putParcelable(DocumentsContract.EXTRA_URI, uri);
return out;
} catch (FileNotFoundException e) {
throw new IllegalStateException("File in " + path + " is not found.", e);
}
}
case GET_MEDIA_URI_CALL: {
// All callers must go through MediaProvider
getContext().enforceCallingPermission(
android.Manifest.permission.WRITE_MEDIA_STORAGE, TAG);
final Uri documentUri = extras.getParcelable(DocumentsContract.EXTRA_URI);
final String docId = DocumentsContract.getDocumentId(documentUri);
try {
final Bundle out = new Bundle();
final Uri uri = Uri.fromFile(getFileForDocId(docId, true));
out.putParcelable(DocumentsContract.EXTRA_URI, uri);
return out;
} catch (FileNotFoundException e) {
throw new IllegalStateException(e);
}
}
default:
Log.w(TAG, "unknown method passed to call(): " + method);
}
}
return bundle;
}
}