/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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
*
* https://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 org.apache.tools.ant.types.selectors.modifiedselector;
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.util.Locale;
import org.apache.tools.ant.BuildException;
Computes a 'hashvalue' for the content of file using
java.security.MessageDigest.
Use of this algorithm doesn't require any additional nested <param>s.
Supported <param>s are:
Digest algorithm parameters
name values description required
algorithm.algorithm
MD5 | SHA (default provider)
name of the algorithm the provider should use
no, defaults to MD5
algorithm.provider
name of the provider to use
no, defaults to null
Version: 2004-07-08 Since: Ant 1.6
/**
* Computes a 'hashvalue' for the content of file using
* java.security.MessageDigest.
* Use of this algorithm doesn't require any additional nested <param>s.
* Supported <param>s are:
* <table>
* <caption>Digest algorithm parameters</caption>
* <tr>
* <th>name</th><th>values</th><th>description</th><th>required</th>
* </tr>
* <tr>
* <td>algorithm.algorithm</td>
* <td>MD5 | SHA (default provider)</td>
* <td>name of the algorithm the provider should use</td>
* <td>no, defaults to MD5</td>
* </tr>
* <tr>
* <td> algorithm.provider</td>
* <td></td>
* <td>name of the provider to use</td>
* <td>no, defaults to <i>null</i></td>
* </tr>
* </table>
*
* @version 2004-07-08
* @since Ant 1.6
*/
public class DigestAlgorithm implements Algorithm {
private static final int BYTE_MASK = 0xFF;
private static final int BUFFER_SIZE = 8192;
// ----- member variables -----
MessageDigest algorithm to be used.
/**
* MessageDigest algorithm to be used.
*/
private String algorithm = "MD5";
MessageDigest Algorithm provider
/**
* MessageDigest Algorithm provider
*/
private String provider = null;
Message Digest instance
/**
* Message Digest instance
*/
private MessageDigest messageDigest = null;
Size of the read buffer to use.
/**
* Size of the read buffer to use.
*/
private int readBufferSize = BUFFER_SIZE;
// ----- Algorithm-Configuration -----
Specifies the algorithm to be used to compute the checksum.
Defaults to "MD5". Other popular algorithms like "SHA" may be used as well.
Params: - algorithm – the digest algorithm to use
/**
* Specifies the algorithm to be used to compute the checksum.
* Defaults to "MD5". Other popular algorithms like "SHA" may be used as well.
* @param algorithm the digest algorithm to use
*/
public void setAlgorithm(String algorithm) {
this.algorithm = algorithm != null
? algorithm.toUpperCase(Locale.ENGLISH) : null;
}
Sets the MessageDigest algorithm provider to be used
to calculate the checksum.
Params: - provider – provider to use
/**
* Sets the MessageDigest algorithm provider to be used
* to calculate the checksum.
* @param provider provider to use
*/
public void setProvider(String provider) {
this.provider = provider;
}
Initialize the security message digest. /** Initialize the security message digest. */
public void initMessageDigest() {
if (messageDigest != null) {
return;
}
if (provider != null && !provider.isEmpty() && !"null".equals(provider)) {
try {
messageDigest = MessageDigest.getInstance(algorithm, provider);
} catch (NoSuchAlgorithmException | NoSuchProviderException e) {
throw new BuildException(e);
}
} else {
try {
messageDigest = MessageDigest.getInstance(algorithm);
} catch (NoSuchAlgorithmException noalgo) {
throw new BuildException(noalgo);
}
}
}
// ----- Logic -----
This algorithm supports only MD5 and SHA.
Returns: true if all is ok, otherwise false.
/**
* This algorithm supports only MD5 and SHA.
* @return <i>true</i> if all is ok, otherwise <i>false</i>.
*/
@Override
public boolean isValid() {
return "SHA".equals(algorithm) || "MD5".equals(algorithm);
}
Computes a value for a file content with the specified digest algorithm.
Params: - file – File object for which the value should be evaluated.
Returns: The value for that file
/**
* Computes a value for a file content with the specified digest algorithm.
* @param file File object for which the value should be evaluated.
* @return The value for that file
*/
// implementation adapted from ...taskdefs.Checksum, thanks to Magesh for hint
@Override
public String getValue(File file) {
if (!file.canRead()) {
return null;
}
initMessageDigest();
byte[] buf = new byte[readBufferSize];
messageDigest.reset();
try (DigestInputStream dis = new DigestInputStream(Files.newInputStream(file.toPath()),
messageDigest)) {
// read the whole stream
while (dis.read(buf, 0, readBufferSize) != -1) {
}
StringBuilder checksumSb = new StringBuilder();
for (byte digestByte : messageDigest.digest()) {
checksumSb.append(String.format("%02x", BYTE_MASK & digestByte));
}
return checksumSb.toString();
} catch (IOException ignored) {
return null;
}
}
Override Object.toString().
Returns: some information about this algorithm.
/**
* Override Object.toString().
* @return some information about this algorithm.
*/
@Override
public String toString() {
return String.format("<DigestAlgorithm:algorithm=%s;provider=%s>",
algorithm, provider);
}
}