| /* |
| * 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.apksig.internal.util; |
| |
| import com.android.apksig.util.DataSink; |
| import com.android.apksig.util.DataSource; |
| import java.io.IOException; |
| import java.nio.ByteBuffer; |
| |
| /** |
| * {@link DataSource} backed by a {@link ByteBuffer}. |
| */ |
| public class ByteBufferDataSource implements DataSource { |
| |
| private final ByteBuffer mBuffer; |
| private final int mSize; |
| |
| /** |
| * Constructs a new {@code ByteBufferDigestSource} based on the data contained in the provided |
| * buffer between the buffer's position and limit. |
| */ |
| public ByteBufferDataSource(ByteBuffer buffer) { |
| this(buffer, true); |
| } |
| |
| /** |
| * Constructs a new {@code ByteBufferDigestSource} based on the data contained in the provided |
| * buffer between the buffer's position and limit. |
| */ |
| private ByteBufferDataSource(ByteBuffer buffer, boolean sliceRequired) { |
| mBuffer = (sliceRequired) ? buffer.slice() : buffer; |
| mSize = buffer.remaining(); |
| } |
| |
| @Override |
| public long size() { |
| return mSize; |
| } |
| |
| @Override |
| public ByteBuffer getByteBuffer(long offset, int size) { |
| checkChunkValid(offset, size); |
| |
| // checkChunkValid ensures that it's OK to cast offset to int. |
| int chunkPosition = (int) offset; |
| int chunkLimit = chunkPosition + size; |
| // Creating a slice of ByteBuffer modifies the state of the source ByteBuffer (position |
| // and limit fields, to be more specific). We thus use synchronization around these |
| // state-changing operations to make instances of this class thread-safe. |
| synchronized (mBuffer) { |
| // ByteBuffer.limit(int) and .position(int) check that that the position >= limit |
| // invariant is not broken. Thus, the only way to safely change position and limit |
| // without caring about their current values is to first set position to 0 or set the |
| // limit to capacity. |
| mBuffer.position(0); |
| |
| mBuffer.limit(chunkLimit); |
| mBuffer.position(chunkPosition); |
| return mBuffer.slice(); |
| } |
| } |
| |
| @Override |
| public void copyTo(long offset, int size, ByteBuffer dest) { |
| dest.put(getByteBuffer(offset, size)); |
| } |
| |
| @Override |
| public void feed(long offset, long size, DataSink sink) throws IOException { |
| if ((size < 0) || (size > mSize)) { |
| throw new IndexOutOfBoundsException("size: " + size + ", source size: " + mSize); |
| } |
| sink.consume(getByteBuffer(offset, (int) size)); |
| } |
| |
| @Override |
| public ByteBufferDataSource slice(long offset, long size) { |
| if ((offset == 0) && (size == mSize)) { |
| return this; |
| } |
| if ((size < 0) || (size > mSize)) { |
| throw new IndexOutOfBoundsException("size: " + size + ", source size: " + mSize); |
| } |
| return new ByteBufferDataSource( |
| getByteBuffer(offset, (int) size), |
| false // no need to slice -- it's already a slice |
| ); |
| } |
| |
| private void checkChunkValid(long offset, long size) { |
| if (offset < 0) { |
| throw new IndexOutOfBoundsException("offset: " + offset); |
| } |
| if (size < 0) { |
| throw new IndexOutOfBoundsException("size: " + size); |
| } |
| if (offset > mSize) { |
| throw new IndexOutOfBoundsException( |
| "offset (" + offset + ") > source size (" + mSize + ")"); |
| } |
| long endOffset = offset + size; |
| if (endOffset < offset) { |
| throw new IndexOutOfBoundsException( |
| "offset (" + offset + ") + size (" + size + ") overflow"); |
| } |
| if (endOffset > mSize) { |
| throw new IndexOutOfBoundsException( |
| "offset (" + offset + ") + size (" + size + ") > source size (" + mSize +")"); |
| } |
| } |
| } |