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// Copyright 2017 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.worker;
import static java.nio.charset.StandardCharsets.UTF_8;
import java.io.ByteArrayOutputStream;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.regex.Pattern;
/**
* An input stream filter that records the first X bytes read from its wrapped stream.
*
* <p>The number bytes to record can be set via {@link #startRecording(int)}}, which also discards
* any already recorded data. The recorded data can be retrieved via {@link
* #getRecordedDataAsString()}.
*/
final class RecordingInputStream extends FilterInputStream {
private static final Pattern NON_PRINTABLE_CHARS =
Pattern.compile("[^\\p{Print}\\t\\r\\n]", Pattern.UNICODE_CHARACTER_CLASS);
private ByteArrayOutputStream recordedData;
private int maxRecordedSize;
RecordingInputStream(InputStream in) {
super(in);
}
/**
* Returns the maximum number of bytes that can still be recorded in our buffer (but not more
* than {@code size}).
*/
private int getRecordableBytes(int size) {
if (recordedData == null) {
return 0;
}
return Math.min(maxRecordedSize - recordedData.size(), size);
}
@Override
public int read() throws IOException {
int bytesRead = super.read();
if (getRecordableBytes(bytesRead) > 0) {
recordedData.write(bytesRead);
}
return bytesRead;
}
@Override
public int read(byte[] b) throws IOException {
int bytesRead = super.read(b);
int recordableBytes = getRecordableBytes(bytesRead);
if (recordableBytes > 0) {
recordedData.write(b, 0, recordableBytes);
}
return bytesRead;
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
int bytesRead = super.read(b, off, len);
int recordableBytes = getRecordableBytes(bytesRead);
if (recordableBytes > 0) {
recordedData.write(b, off, recordableBytes);
}
return bytesRead;
}
public void startRecording(int maxSize) {
recordedData = new ByteArrayOutputStream(maxSize);
maxRecordedSize = maxSize;
}
/**
* Reads whatever remaining data is available on the input stream if we still have space left in
* the recording buffer, in order to maximize the usefulness of the recorded data for the
* caller.
*/
public void readRemaining() {
try {
byte[] dummy = new byte[getRecordableBytes(available())];
read(dummy);
} catch (IOException e) {
// Ignore.
}
}
/**
* Returns the recorded data as a string, where non-printable characters are replaced with a '?'
* symbol.
*/
public String getRecordedDataAsString() {
String recordedString = new String(recordedData.toByteArray(), UTF_8);
return NON_PRINTABLE_CHARS.matcher(recordedString).replaceAll("?").trim();
}
}
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