| // Copyright 2020 The Bazel Authors. All rights reserved. |
| // |
| // 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.google.devtools.build.lib.bazel.repository.downloader; |
| |
| import com.google.common.hash.HashCode; |
| import com.google.common.hash.Hasher; |
| import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadCompatible; |
| import java.io.IOException; |
| import java.io.OutputStream; |
| import javax.annotation.Nullable; |
| import javax.annotation.WillCloseWhenClosed; |
| |
| /** |
| * Output stream that guarantees its contents matches a hash code. |
| * |
| * <p>The actual checksum is computed gradually as the output is written. If it doesn't match, then |
| * an {@link IOException} will be thrown when {@link #close()} is called. This error will be thrown |
| * multiple times if these methods are called again for some reason. |
| * |
| * <p>Note that as the checksum can only be computed once the stream is closed, data will be written |
| * to the underlying stream regardless of whether it matches the expected checksum. |
| * |
| * <p>This class is not thread safe, but it is safe to message pass this object between threads. |
| */ |
| @ThreadCompatible |
| public final class HashOutputStream extends OutputStream { |
| |
| private final OutputStream delegate; |
| private final Hasher hasher; |
| private final HashCode code; |
| @Nullable private volatile HashCode actual; |
| |
| public HashOutputStream(@WillCloseWhenClosed OutputStream delegate, Checksum checksum) { |
| this.delegate = delegate; |
| this.hasher = checksum.getKeyType().newHasher(); |
| this.code = checksum.getHashCode(); |
| } |
| |
| @Override |
| public void write(int buffer) throws IOException { |
| hasher.putByte((byte) buffer); |
| delegate.write(buffer); |
| } |
| |
| @Override |
| public void write(byte[] buffer) throws IOException { |
| hasher.putBytes(buffer); |
| delegate.write(buffer); |
| } |
| |
| @Override |
| public void write(byte[] buffer, int offset, int length) throws IOException { |
| hasher.putBytes(buffer, offset, length); |
| delegate.write(buffer, offset, length); |
| } |
| |
| @Override |
| public void flush() throws IOException { |
| delegate.flush(); |
| } |
| |
| @Override |
| public void close() throws IOException { |
| delegate.close(); |
| check(); |
| } |
| |
| private void check() throws IOException { |
| if (actual == null) { |
| actual = hasher.hash(); |
| } |
| if (!code.equals(actual)) { |
| throw new UnrecoverableHttpException( |
| String.format("Checksum was %s but wanted %s", actual, code)); |
| } |
| } |
| } |