| /* |
| * Copyright (C) 2016 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.internal.os; |
| |
| import android.annotation.NonNull; |
| import android.annotation.Nullable; |
| import android.os.IProxyFileDescriptorCallback; |
| import android.os.ParcelFileDescriptor; |
| import android.system.ErrnoException; |
| import android.system.OsConstants; |
| import android.util.Log; |
| import android.util.SparseArray; |
| import com.android.internal.annotations.GuardedBy; |
| import com.android.internal.util.Preconditions; |
| |
| import java.io.File; |
| import java.io.FileNotFoundException; |
| import java.io.IOException; |
| |
| public class FuseAppLoop { |
| private static final String TAG = "FuseAppLoop"; |
| private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG); |
| public static final int ROOT_INODE = 1; |
| private static final int MIN_INODE = 2; |
| |
| private final Object mLock = new Object(); |
| private final File mParent; |
| |
| @GuardedBy("mLock") |
| private final SparseArray<CallbackEntry> mCallbackMap = new SparseArray<>(); |
| |
| @GuardedBy("mLock") |
| private boolean mActive = true; |
| |
| /** |
| * Sequential number can be used as file name and inode in AppFuse. |
| * 0 is regarded as an error, 1 is mount point. So we start the number from 2. |
| */ |
| @GuardedBy("mLock") |
| private int mNextInode = MIN_INODE; |
| |
| private FuseAppLoop(@NonNull File parent) { |
| mParent = parent; |
| } |
| |
| public static @NonNull FuseAppLoop open( |
| @NonNull File parent, @NonNull ParcelFileDescriptor fd) { |
| Preconditions.checkNotNull(parent); |
| Preconditions.checkNotNull(fd); |
| final FuseAppLoop bridge = new FuseAppLoop(parent); |
| final int rawFd = fd.detachFd(); |
| new Thread(new Runnable() { |
| @Override |
| public void run() { |
| bridge.native_start_loop(rawFd); |
| } |
| }, TAG).start(); |
| return bridge; |
| } |
| |
| public @NonNull ParcelFileDescriptor openFile(int mode, IProxyFileDescriptorCallback callback) |
| throws UnmountedException, IOException { |
| int id; |
| synchronized (mLock) { |
| if (!mActive) { |
| throw new UnmountedException(); |
| } |
| if (mCallbackMap.size() >= Integer.MAX_VALUE - MIN_INODE) { |
| throw new IOException("Too many opened files."); |
| } |
| while (true) { |
| id = mNextInode; |
| mNextInode++; |
| if (mNextInode < 0) { |
| mNextInode = MIN_INODE; |
| } |
| if (mCallbackMap.get(id) == null) { |
| break; |
| } |
| } |
| |
| // Register callback after we succeed to create pfd. |
| mCallbackMap.put(id, new CallbackEntry(callback)); |
| } |
| try { |
| return ParcelFileDescriptor.open(new File(mParent, String.valueOf(id)), mode); |
| } catch (FileNotFoundException error) { |
| synchronized (mLock) { |
| mCallbackMap.remove(id); |
| } |
| throw error; |
| } |
| } |
| |
| public @Nullable File getMountPoint() { |
| synchronized (mLock) { |
| return mActive ? mParent : null; |
| } |
| } |
| |
| private CallbackEntry getCallbackEntryOrThrowLocked(long inode) throws ErrnoException { |
| final CallbackEntry entry = mCallbackMap.get(checkInode(inode)); |
| if (entry != null) { |
| return entry; |
| } else { |
| throw new ErrnoException("getCallbackEntry", OsConstants.ENOENT); |
| } |
| } |
| |
| // Called by JNI. |
| @SuppressWarnings("unused") |
| private long onGetSize(long inode) { |
| synchronized(mLock) { |
| try { |
| return getCallbackEntryOrThrowLocked(inode).callback.onGetSize(); |
| } catch (ErrnoException exp) { |
| return -exp.errno; |
| } |
| } |
| } |
| |
| // Called by JNI. |
| @SuppressWarnings("unused") |
| private int onOpen(long inode) { |
| synchronized(mLock) { |
| try { |
| final CallbackEntry entry = getCallbackEntryOrThrowLocked(inode); |
| if (entry.opened) { |
| throw new ErrnoException("onOpen", OsConstants.EMFILE); |
| } |
| entry.opened = true; |
| // Use inode as file handle. It's OK because AppFuse does not allow to open the same |
| // file twice. |
| return (int) inode; |
| } catch (ErrnoException exp) { |
| return -exp.errno; |
| } |
| } |
| } |
| |
| // Called by JNI. |
| @SuppressWarnings("unused") |
| private int onFsync(long inode) { |
| synchronized(mLock) { |
| try { |
| getCallbackEntryOrThrowLocked(inode).callback.onFsync(); |
| return 0; |
| } catch (ErrnoException exp) { |
| return -exp.errno; |
| } |
| } |
| } |
| |
| // Called by JNI. |
| @SuppressWarnings("unused") |
| private int onRelease(long inode) { |
| synchronized(mLock) { |
| mCallbackMap.remove(checkInode(inode)); |
| if (mCallbackMap.size() == 0) { |
| mActive = false; |
| return -1; |
| } |
| return 0; |
| } |
| } |
| |
| // Called by JNI. |
| @SuppressWarnings("unused") |
| private int onRead(long inode, long offset, int size, byte[] bytes) { |
| synchronized(mLock) { |
| try { |
| return getCallbackEntryOrThrowLocked(inode).callback.onRead(offset, size, bytes); |
| } catch (ErrnoException exp) { |
| return -exp.errno; |
| } |
| } |
| } |
| |
| // Called by JNI. |
| @SuppressWarnings("unused") |
| private int onWrite(long inode, long offset, int size, byte[] bytes) { |
| synchronized(mLock) { |
| try { |
| return getCallbackEntryOrThrowLocked(inode).callback.onWrite(offset, size, bytes); |
| } catch (ErrnoException exp) { |
| return -exp.errno; |
| } |
| } |
| } |
| |
| native boolean native_start_loop(int fd); |
| |
| private static int checkInode(long inode) { |
| Preconditions.checkArgumentInRange(inode, MIN_INODE, Integer.MAX_VALUE, "checkInode"); |
| return (int) inode; |
| } |
| |
| public static class UnmountedException extends Exception {} |
| |
| private static class CallbackEntry { |
| final IProxyFileDescriptorCallback callback; |
| boolean opened; |
| CallbackEntry(IProxyFileDescriptorCallback callback) { |
| Preconditions.checkNotNull(callback); |
| this.callback = callback; |
| } |
| } |
| } |