/*
* Copyright (C) 2015 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.mtp;
import android.annotation.WorkerThread;
import android.os.ParcelFileDescriptor;
import android.os.Process;
import android.os.storage.StorageManager;
import android.system.ErrnoException;
import android.system.OsConstants;
import android.util.Log;
import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.util.Preconditions;
import com.android.mtp.annotations.UsedByNative;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
public class AppFuse {
static {
System.loadLibrary("appfuse_jni");
}
private static final boolean DEBUG = false;
/**
* Max read amount specified at the FUSE kernel implementation.
* The value is copied from sdcard.c.
*/
@UsedByNative("com_android_mtp_AppFuse.cpp")
static final int MAX_READ = 128 * 1024;
@UsedByNative("com_android_mtp_AppFuse.cpp")
static final int MAX_WRITE = 256 * 1024;
private final String mName;
private final Callback mCallback;
/**
* Buffer for read bytes request.
* Don't use the buffer from the out of AppFuseMessageThread.
*/
private byte[] mBuffer = new byte[Math.max(MAX_READ, MAX_WRITE)];
private Thread mMessageThread;
private ParcelFileDescriptor mDeviceFd;
AppFuse(String name, Callback callback) {
mName = name;
mCallback = callback;
}
void mount(StorageManager storageManager) throws IOException {
Preconditions.checkState(mDeviceFd == null);
mDeviceFd = storageManager.mountAppFuse(mName);
mMessageThread = new AppFuseMessageThread(mDeviceFd.dup().detachFd());
mMessageThread.start();
}
@VisibleForTesting
void close() {
try {
// Remote side of ParcelFileDescriptor is tracking the close of mDeviceFd, and unmount
// the corresponding fuse file system. The mMessageThread will receive ENODEV, and
// then terminate itself.
mDeviceFd.close();
mMessageThread.join();
} catch (IOException exp) {
Log.e(MtpDocumentsProvider.TAG, "Failed to close device FD.", exp);
} catch (InterruptedException exp) {
Log.e(MtpDocumentsProvider.TAG, "Failed to terminate message thread.", exp);
}
}
/**
* Opens a file on app fuse and returns ParcelFileDescriptor.
*
* @param i ID for opened file.
* @param mode Mode for opening file.
* @see ParcelFileDescriptor#MODE_READ_ONLY
* @see ParcelFileDescriptor#MODE_WRITE_ONLY
*/
public ParcelFileDescriptor openFile(int i, int mode) throws FileNotFoundException {
Preconditions.checkArgument(
mode == ParcelFileDescriptor.MODE_READ_ONLY ||
mode == (ParcelFileDescriptor.MODE_WRITE_ONLY |
ParcelFileDescriptor.MODE_TRUNCATE));
return ParcelFileDescriptor.open(new File(
getMountPoint(),
Integer.toString(i)),
mode);
}
File getMountPoint() {
return new File("/mnt/appfuse/" + Process.myUid() + "_" + mName);
}
static interface Callback {
/**
* Returns file size for the given inode.
* @param inode
* @return File size. Must not be negative.
* @throws FileNotFoundException
*/
long getFileSize(int inode) throws FileNotFoundException;
/**
* Returns file bytes for the give inode.
* @param inode
* @param offset Offset for file bytes.
* @param size Size for file bytes.
* @param bytes Buffer to store file bytes.
* @return Number of read bytes. Must not be negative.
* @throws IOException
*/
long readObjectBytes(int inode, long offset, long size, byte[] bytes) throws IOException;
/**
* Handles writing bytes for the give inode.
* @param fileHandle
* @param inode
* @param offset Offset for file bytes.
* @param size Size for file bytes.
* @param bytes Buffer to store file bytes.
* @return Number of read bytes. Must not be negative.
* @throws IOException
*/
int writeObjectBytes(long fileHandle, int inode, long offset, int size, byte[] bytes)
throws IOException, ErrnoException;
/**
* Flushes bytes for file handle.
* @param fileHandle
* @throws IOException
* @throws ErrnoException
*/
void flushFileHandle(long fileHandle) throws IOException, ErrnoException;
/**
* Closes file handle.
* @param fileHandle
* @throws IOException
*/
void closeFileHandle(long fileHandle) throws IOException, ErrnoException;
}
@UsedByNative("com_android_mtp_AppFuse.cpp")
@WorkerThread
private long getFileSize(int inode) {
try {
return mCallback.getFileSize(inode);
} catch (Exception error) {
return -getErrnoFromException(error);
}
}
@UsedByNative("com_android_mtp_AppFuse.cpp")
@WorkerThread
private long readObjectBytes(int inode, long offset, long size) {
if (offset < 0 || size < 0 || size > MAX_READ) {
return -OsConstants.EINVAL;
}
try {
// It's OK to share the same mBuffer among requests because the requests are processed
// by AppFuseMessageThread sequentially.
return mCallback.readObjectBytes(inode, offset, size, mBuffer);
} catch (Exception error) {
return -getErrnoFromException(error);
}
}
@UsedByNative("com_android_mtp_AppFuse.cpp")
@WorkerThread
private /* unsgined */ int writeObjectBytes(long fileHandler,
int inode,
/* unsigned */ long offset,
/* unsigned */ int size,
byte[] bytes) {
try {
return mCallback.writeObjectBytes(fileHandler, inode, offset, size, bytes);
} catch (Exception error) {
return -getErrnoFromException(error);
}
}
@UsedByNative("com_android_mtp_AppFuse.cpp")
@WorkerThread
private int flushFileHandle(long fileHandle) {
try {
mCallback.flushFileHandle(fileHandle);
return 0;
} catch (Exception error) {
return -getErrnoFromException(error);
}
}
@UsedByNative("com_android_mtp_AppFuse.cpp")
@WorkerThread
private int closeFileHandle(long fileHandle) {
try {
mCallback.closeFileHandle(fileHandle);
return 0;
} catch (Exception error) {
return -getErrnoFromException(error);
}
}
private static int getErrnoFromException(Exception error) {
if (DEBUG) {
Log.e(MtpDocumentsProvider.TAG, "AppFuse callbacks", error);
}
if (error instanceof FileNotFoundException) {
return OsConstants.ENOENT;
} else if (error instanceof IOException) {
return OsConstants.EIO;
} else if (error instanceof UnsupportedOperationException) {
return OsConstants.ENOTSUP;
} else if (error instanceof IllegalArgumentException) {
return OsConstants.EINVAL;
} else {
return OsConstants.EIO;
}
}
private native void native_start_app_fuse_loop(int fd);
private class AppFuseMessageThread extends Thread {
/**
* File descriptor used by native loop.
* It's owned by native loop and does not need to close here.
*/
private final int mRawFd;
AppFuseMessageThread(int fd) {
super("AppFuseMessageThread");
mRawFd = fd;
}
@Override
public void run() {
native_start_app_fuse_loop(mRawFd);
}
}
}