// 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.util; import static java.nio.charset.StandardCharsets.UTF_8; import com.google.common.collect.Iterables; import com.google.devtools.build.lib.vfs.Path; import com.google.devtools.build.lib.vfs.PathFragment; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.util.Map; import java.util.UUID; /** * Simplified wrapper for MD5 message digests. See also * com.google.math.crypto.MD5HMAC for a similar interface. * * @see java.security.MessageDigest */ public final class Fingerprint { private final MessageDigest md; /** * Creates and initializes a new MD5 object; if this fails, Java must be * installed incorrectly. */ public Fingerprint() { try { md = MessageDigest.getInstance("md5"); } catch (NoSuchAlgorithmException e) { throw new RuntimeException("MD5 not available"); } } /** * Completes the hash computation by doing final operations, e.g., padding. * *
This method has the side-effect of resetting the underlying digest computer. * * @return the MD5 digest as a 16-byte array * @see java.security.MessageDigest#digest() */ public byte[] digestAndReset() { return md.digest(); } /** * Completes the hash computation and returns the digest as a string. * *
This method has the side-effect of resetting the underlying digest computer.
*
* @return the MD5 digest as a 32-character string of hexadecimal digits
* @see com.google.math.crypto.MD5HMAC#toString()
*/
public String hexDigestAndReset() {
return hexDigest(digestAndReset());
}
/**
* Returns a string representation of an MD5 digest.
*
* @param digest the MD5 digest, perhaps from a previous call to digest
* @return the digest as a 32-character string of hexadecimal digits
*/
public static String hexDigest(byte[] digest) {
StringBuilder b = new StringBuilder(32);
for (int i = 0; i < digest.length; i++) {
int n = digest[i];
b.append("0123456789abcdef".charAt((n >> 4) & 0xF));
b.append("0123456789abcdef".charAt(n & 0xF));
}
return b.toString();
}
/**
* Override of Object.toString to return a string for the MD5 digest without
* finalizing the digest computation. Calling hexDigest() instead will
* finalize the digest computation.
*
* @return the string returned by hexDigest()
*/
@Override
public String toString() {
try {
// MD5 does support cloning, so this should not fail
return hexDigest(((MessageDigest) md.clone()).digest());
} catch (CloneNotSupportedException e) {
// MessageDigest does not support cloning,
// so just return the toString() on the MessageDigest.
return md.toString();
}
}
/**
* Updates the digest with 0 or more bytes.
*
* @param input the array of bytes with which to update the digest
* @see java.security.MessageDigest#update(byte[])
*/
public Fingerprint addBytes(byte[] input) {
md.update(input);
return this;
}
/**
* Updates the digest with the specified number of bytes starting at offset.
*
* @param input the array of bytes with which to update the digest
* @param offset the offset into the array
* @param len the number of bytes to use
* @see java.security.MessageDigest#update(byte[], int, int)
*/
public Fingerprint addBytes(byte[] input, int offset, int len) {
md.update(input, offset, len);
return this;
}
/**
* Updates the digest with a boolean value.
*/
public Fingerprint addBoolean(boolean input) {
addBytes(new byte[] { (byte) (input ? 1 : 0) });
return this;
}
/**
* Updates the digest with the little-endian bytes of a given int value.
*
* @param input the integer with which to update the digest
*/
public Fingerprint addInt(int input) {
md.update(new byte[] {
(byte) input,
(byte) (input >> 8),
(byte) (input >> 16),
(byte) (input >> 24),
});
return this;
}
/**
* Updates the digest with the little-endian bytes of a given long value.
*
* @param input the long with which to update the digest
*/
public Fingerprint addLong(long input) {
md.update(new byte[]{
(byte) input,
(byte) (input >> 8),
(byte) (input >> 16),
(byte) (input >> 24),
(byte) (input >> 32),
(byte) (input >> 40),
(byte) (input >> 48),
(byte) (input >> 56),
});
return this;
}
/**
* Updates the digest with a UUID.
*
* @param uuid the UUID with which to update the digest. Must not be null.
*/
public Fingerprint addUUID(UUID uuid) {
addLong(uuid.getLeastSignificantBits());
addLong(uuid.getMostSignificantBits());
return this;
}
/**
* Updates the digest with a String using its length plus its UTF8 encoded bytes.
*
* @param input the String with which to update the digest
* @see java.security.MessageDigest#update(byte[])
*/
public Fingerprint addString(String input) {
byte[] bytes = input.getBytes(UTF_8);
addInt(bytes.length);
md.update(bytes);
return this;
}
/**
* Updates the digest with a String using its length and content.
*
* @param input the String with which to update the digest
* @see java.security.MessageDigest#update(byte[])
*/
public Fingerprint addStringLatin1(String input) {
addInt(input.length());
byte[] bytes = new byte[input.length()];
for (int i = 0; i < input.length(); i++) {
bytes[i] = (byte) input.charAt(i);
}
md.update(bytes);
return this;
}
/**
* Updates the digest with a Path.
*
* @param input the Path with which to update the digest.
*/
public Fingerprint addPath(Path input) {
addStringLatin1(input.getPathString());
return this;
}
/**
* Updates the digest with a Path.
*
* @param input the Path with which to update the digest.
*/
public Fingerprint addPath(PathFragment input) {
addStringLatin1(input.getPathString());
return this;
}
/**
* Updates the digest with inputs by iterating over them and invoking
* {@code #addString(String)} on each element.
*
* @param inputs the inputs with which to update the digest
*/
public Fingerprint addStrings(Iterable