com.sleepycat.je.util.LogVerificationInputStream Maven / Gradle / Ivy
/*-
* Copyright (C) 2002, 2018, Oracle and/or its affiliates. All rights reserved.
*
* This file was distributed by Oracle as part of a version of Oracle Berkeley
* DB Java Edition made available at:
*
* http://www.oracle.com/technetwork/database/database-technologies/berkeleydb/downloads/index.html
*
* Please see the LICENSE file included in the top-level directory of the
* appropriate version of Oracle Berkeley DB Java Edition for a copy of the
* license and additional information.
*/
package com.sleepycat.je.util;
import java.io.IOException;
import java.io.InputStream;
import com.sleepycat.je.DbInternal;
import com.sleepycat.je.Environment;
import com.sleepycat.je.EnvironmentFailureException;
import com.sleepycat.je.dbi.EnvironmentImpl;
import com.sleepycat.je.utilint.LogVerifier;
/**
* Verifies the checksums in an {@code InputStream} for a log file in a JE
* {@code Environment}.
*
* This {@code InputStream} reads input from some other given {@code
* InputStream}, and verifies checksums while reading. Its primary intended
* use is to verify log files that are being copied as part of a programmatic
* backup. It is critical that invalid files are not added to a backup set,
* since then both the live environment and the backup will be invalid.
*
* The following example verifies log files as they are being copied. The
* {@link DbBackup} class should normally be used to obtain the array of files
* to be copied.
*
*
*
*
* void copyFiles(final Environment env,
* final String[] fileNames,
* final File destDir,
* final int bufSize)
* throws IOException, DatabaseException {
*
* final File srcDir = env.getHome();
*
* for (final String fileName : fileNames) {
*
* final File destFile = new File(destDir, fileName);
* final FileOutputStream fos = new FileOutputStream(destFile);
*
* final File srcFile = new File(srcDir, fileName);
* final FileInputStream fis = new FileInputStream(srcFile);
* final LogVerificationInputStream vis =
* new LogVerificationInputStream(env, fis, fileName);
*
* final byte[] buf = new byte[bufSize];
*
* try {
* while (true) {
* final int len = vis.read(buf);
* if (len < 0) {
* break;
* }
* fos.write(buf, 0, len);
* }
* } finally {
* fos.close();
* vis.close();
* }
* }
* }
*
*
* It is important to read the entire underlying input stream until the
* end-of-file is reached to detect incomplete entries at the end of the log
* file.
*
* Note that {@code mark} and {@code reset} are not supported and {@code
* markSupported} returns false. The default {@link InputStream}
* implementation of these methods is used.
*
* @see DbBackup
* @see DbVerifyLog
*/
public class LogVerificationInputStream extends InputStream {
private static final int SKIP_BUF_SIZE = 2048;
private final InputStream in;
private final LogVerifier verifier;
private byte[] skipBuf;
/**
* Creates a verification input stream.
*
* @param env the {@code Environment} associated with the log.
*
* @param in the underlying {@code InputStream} for the log to be read.
*
* @param fileName the file name of the input stream, for reporting in the
* {@code LogVerificationException}. This should be a simple file name of
* the form {@code NNNNNNNN.jdb}, where NNNNNNNN is the file number in
* hexadecimal format.
*
* @throws EnvironmentFailureException if an unexpected, internal or
* environment-wide failure occurs.
*/
public LogVerificationInputStream(final Environment env,
final InputStream in,
final String fileName) {
this(DbInternal.getNonNullEnvImpl(env), in, fileName, -1L);
}
/**
* Internal constructor. If fileNum is less than zero, it is derived from
* fileName.
*/
LogVerificationInputStream(final EnvironmentImpl envImpl,
final InputStream in,
final String fileName,
final long fileNum) {
verifier = new LogVerifier(envImpl, fileName, fileNum);
this.in = in;
}
/**
* {@inheritDoc}
*
* This method reads the underlying {@code InputStream} and verifies the
* contents of the stream.
*
* @throws LogVerificationException if a checksum cannot be verified or a
* log entry is determined to be invalid by examining its contents.
*
* @throws EnvironmentFailureException if an unexpected, internal or
* environment-wide failure occurs.
*/
@Override
public int read()
throws IOException {
/*
* This method will rarely, if ever, be called when reading a file, so
* allocating a new byte array is not a performance issue and is the
* simplest approach.
*/
final byte[] b = new byte[1];
final int lenRead = read(b, 0, 1);
return (lenRead <= 0) ? lenRead : (b[0] & 0xff);
}
/**
* {@inheritDoc}
*
* This method reads the underlying {@code InputStream} and verifies the
* contents of the stream.
*
* @throws LogVerificationException if a checksum cannot be verified or a
* log entry is determined to be invalid by examining its contents.
*
* @throws EnvironmentFailureException if an unexpected, internal or
* environment-wide failure occurs.
*/
@Override
public int read(final byte b[])
throws IOException {
return read(b, 0, b.length);
}
/**
* {@inheritDoc}
*
* This method reads the underlying {@code InputStream} and verifies the
* contents of the stream.
*
* @throws LogVerificationException if a checksum cannot be verified or a
* log entry is determined to be invalid by examining its contents.
*
* @throws EnvironmentFailureException if an unexpected, internal or
* environment-wide failure occurs.
*/
@Override
public int read(final byte b[], final int off, final int len)
throws IOException {
final int lenRead = in.read(b, off, len);
if (lenRead <= 0) {
if (lenRead < 0) {
verifier.verifyAtEof();
}
return lenRead;
}
verifier.verify(b, off, lenRead);
return lenRead;
}
/**
* {@inheritDoc}
*
* This method reads the underlying {@code InputStream} in order to
* skip the required number of bytes and verifies the contents of the
* stream. A temporary buffer is allocated lazily for reading.
*
* @throws LogVerificationException if a checksum cannot be verified or a
* log entry is determined to be invalid by examining its contents.
*
* @throws EnvironmentFailureException if an unexpected, internal or
* environment-wide failure occurs.
*/
@Override
public long skip(final long bytesToSkip)
throws IOException {
if (bytesToSkip <= 0) {
return 0;
}
/*
* Like InputStream.skip, we lazily allocate a skip buffer. We must
* read the data in order to validate the checksum. Unlike the
* InputStream.skip implementation, we cannot use a static buffer
* because we do process the data and cannot allow multiple threads to
* share the same buffer.
*/
if (skipBuf == null) {
skipBuf = new byte[SKIP_BUF_SIZE];
}
long remaining = bytesToSkip;
while (remaining > 0) {
final int lenRead = read
(skipBuf, 0, (int) Math.min(SKIP_BUF_SIZE, remaining));
if (lenRead < 0) {
break;
}
remaining -= lenRead;
}
return bytesToSkip - remaining;
}
/**
* {@inheritDoc}
*
* This method simply performs in.available().
*/
@Override
public int available()
throws IOException {
return in.available();
}
/**
* {@inheritDoc}
*
*
This method simply performs {@code in.close()}.
*/
@Override
public void close()
throws IOException {
in.close();
}
}