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// Copyright 2014 Google Inc. 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;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.hash.Hasher;
import com.google.common.hash.Hashing;
import com.google.devtools.build.lib.vfs.Path;
import com.google.devtools.build.lib.vfs.PathFragment;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;
/**
* Helper class for downloading a file from a URL.
*/
public class HttpDownloader {
private static final int BUFFER_SIZE = 2048;
private final URL url;
private final String sha256;
private final Path outputDirectory;
HttpDownloader(URL url, String sha256, Path outputDirectory) {
this.url = url;
this.sha256 = sha256;
this.outputDirectory = outputDirectory;
}
/**
* Attempt to download a file from the repository's URL. Returns the path to the file downloaded.
*/
public Path download() throws IOException {
String filename = new PathFragment(url.getPath()).getBaseName();
if (filename.isEmpty()) {
filename = "temp";
}
Path destination = outputDirectory.getRelative(filename);
try (OutputStream outputStream = destination.getOutputStream()) {
ReadableByteChannel rbc = getChannel(url);
ByteBuffer byteBuffer = ByteBuffer.allocate(BUFFER_SIZE);
while (rbc.read(byteBuffer) > 0) {
byteBuffer.flip();
while (byteBuffer.hasRemaining()) {
outputStream.write(byteBuffer.get());
}
}
} catch (IOException e) {
throw new IOException(
"Error downloading " + url + " to " + destination + ": " + e.getMessage());
}
try {
String downloadedSha256 = getSha256(destination);
if (!downloadedSha256.equals(sha256)) {
throw new IOException(
"Downloaded file at " + destination + " has SHA-256 of " + downloadedSha256
+ ", does not match expected SHA-256 (" + sha256 + ")");
}
} catch (IOException e) {
throw new IOException(
"Could not hash file " + destination + ": " + e.getMessage() + ", expected SHA-256 of "
+ sha256 + ")");
}
return destination;
}
@VisibleForTesting
protected ReadableByteChannel getChannel(URL url) throws IOException {
return Channels.newChannel(url.openStream());
}
private String getSha256(Path path) throws IOException {
Hasher hasher = Hashing.sha256().newHasher();
byte byteBuffer[] = new byte[BUFFER_SIZE];
try (InputStream stream = path.getInputStream()) {
int numBytesRead = stream.read(byteBuffer);
while (numBytesRead != -1) {
if (numBytesRead != 0) {
// If more than 0 bytes were read, add them to the hash.
hasher.putBytes(byteBuffer, 0, numBytesRead);
}
numBytesRead = stream.read(byteBuffer);
}
}
return hasher.hash().toString();
}
}
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