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      1 /*
      2  * Copyright (C) 2016 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.tools.build.apkzlib.zip.utils;
     18 
     19 import com.google.common.hash.HashCode;
     20 import com.google.common.hash.HashFunction;
     21 import com.google.common.io.ByteProcessor;
     22 import com.google.common.io.ByteSink;
     23 import com.google.common.io.ByteSource;
     24 import com.google.common.io.CharSource;
     25 import java.io.IOException;
     26 import java.io.InputStream;
     27 import java.io.OutputStream;
     28 import java.nio.charset.Charset;
     29 import javax.annotation.Nonnull;
     30 import javax.annotation.Nullable;
     31 
     32 /**
     33  * Closeable byte source that delegates to another byte source.
     34  */
     35 public class CloseableDelegateByteSource extends CloseableByteSource {
     36 
     37     /**
     38      * The byte source we delegate all operations to. {@code null} if disposed.
     39      */
     40     @Nullable
     41     private ByteSource inner;
     42 
     43     /**
     44      * Size of the byte source. This is the same as {@code inner.size()} (when {@code inner}
     45      * is not {@code null}), but we keep it separate to avoid calling {@code inner.size()}
     46      * because it might throw {@code IOException}.
     47      */
     48     private final long mSize;
     49 
     50     /**
     51      * Creates a new byte source.
     52      *
     53      * @param inner the inner byte source
     54      * @param size the size of the source
     55      */
     56     public CloseableDelegateByteSource(@Nonnull ByteSource inner, long size) {
     57         this.inner = inner;
     58         mSize = size;
     59     }
     60 
     61     /**
     62      * Obtains the inner byte source. Will throw an exception if the inner by byte source has
     63      * been disposed of.
     64      *
     65      * @return the inner byte source
     66      */
     67     @Nonnull
     68     private synchronized ByteSource get() {
     69         if (inner == null) {
     70             throw new ByteSourceDisposedException();
     71         }
     72 
     73         return inner;
     74     }
     75 
     76     /**
     77      * Mark the byte source as disposed.
     78      */
     79     @Override
     80     protected synchronized void innerClose() throws IOException {
     81         if (inner == null) {
     82             return;
     83         }
     84 
     85         inner = null;
     86     }
     87 
     88     /**
     89      * Obtains the size of this byte source. Equivalent to {@link #size()} but not throwing
     90      * {@code IOException}.
     91      *
     92      * @return the size of the byte source
     93      */
     94     public long sizeNoException() {
     95         return mSize;
     96     }
     97 
     98     @Override
     99     public CharSource asCharSource(Charset charset) {
    100         return get().asCharSource(charset);
    101     }
    102 
    103     @Override
    104     public InputStream openBufferedStream() throws IOException {
    105         return get().openBufferedStream();
    106     }
    107 
    108     @Override
    109     public ByteSource slice(long offset, long length) {
    110         return get().slice(offset, length);
    111     }
    112 
    113     @Override
    114     public boolean isEmpty() throws IOException {
    115         return get().isEmpty();
    116     }
    117 
    118     @Override
    119     public long size() throws IOException {
    120         return get().size();
    121     }
    122 
    123     @Override
    124     public long copyTo(@Nonnull OutputStream output) throws IOException {
    125         return get().copyTo(output);
    126     }
    127 
    128     @Override
    129     public long copyTo(@Nonnull ByteSink sink) throws IOException {
    130         return get().copyTo(sink);
    131     }
    132 
    133     @Override
    134     public byte[] read() throws IOException {
    135         return get().read();
    136     }
    137 
    138     @Override
    139     public <T> T read(@Nonnull ByteProcessor<T> processor) throws IOException {
    140         return get().read(processor);
    141     }
    142 
    143     @Override
    144     public HashCode hash(HashFunction hashFunction) throws IOException {
    145         return get().hash(hashFunction);
    146     }
    147 
    148     @Override
    149     public boolean contentEquals(@Nonnull ByteSource other) throws IOException {
    150         return get().contentEquals(other);
    151     }
    152 
    153     @Override
    154     public InputStream openStream() throws IOException {
    155         return get().openStream();
    156     }
    157 
    158     /**
    159      * Exception thrown when trying to use a byte source that has been disposed.
    160      */
    161     private static class ByteSourceDisposedException extends RuntimeException {
    162 
    163         /**
    164          * Creates a new exception.
    165          */
    166         private ByteSourceDisposedException() {
    167             super("Byte source was created by a ByteTracker and is now disposed. If you see "
    168                     + "this message, then there is a bug.");
    169         }
    170     }
    171 }
    172