| // Copyright 2014 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.exec; |
| |
| import static java.nio.charset.StandardCharsets.US_ASCII; |
| |
| import com.google.common.io.BaseEncoding; |
| import com.google.devtools.build.lib.actions.cache.VirtualActionInput; |
| import com.google.devtools.build.lib.util.Pair; |
| import com.google.protobuf.ByteString; |
| import com.google.protobuf.MessageLite; |
| |
| import java.io.IOException; |
| import java.io.OutputStream; |
| import java.nio.ByteBuffer; |
| import java.security.MessageDigest; |
| import java.security.NoSuchAlgorithmException; |
| |
| /** |
| * A utility class for obtaining MD5 digests. |
| * Digests are represented as 32 characters in lowercase ASCII. |
| */ |
| public class Digest { |
| |
| public static final ByteString EMPTY_DIGEST = fromContent(new byte[]{}); |
| |
| private Digest() { |
| } |
| |
| /** |
| * Get the digest from the given byte array. |
| * @param bytes the byte array. |
| * @return a digest. |
| */ |
| public static ByteString fromContent(byte[] bytes) { |
| MessageDigest md = newBuilder(); |
| md.update(bytes, 0, bytes.length); |
| return toByteString(BaseEncoding.base16().lowerCase().encode(md.digest())); |
| } |
| |
| /** |
| * Get the digest from the given ByteBuffer. |
| * @param buffer the ByteBuffer. |
| * @return a digest. |
| */ |
| public static ByteString fromBuffer(ByteBuffer buffer) { |
| MessageDigest md = newBuilder(); |
| md.update(buffer); |
| return toByteString(BaseEncoding.base16().lowerCase().encode(md.digest())); |
| } |
| |
| /** |
| * Gets the digest of the given proto. |
| * |
| * @param proto a protocol buffer. |
| * @return the digest. |
| */ |
| public static ByteString fromProto(MessageLite proto) { |
| MD5OutputStream md5Stream = new MD5OutputStream(); |
| try { |
| proto.writeTo(md5Stream); |
| } catch (IOException e) { |
| throw new IllegalStateException("Unexpected IOException: ", e); |
| } |
| return toByteString(md5Stream.getDigest()); |
| } |
| |
| /** |
| * Gets the digest and size of a given VirtualActionInput. |
| * |
| * @param input the VirtualActionInput. |
| * @return the digest and size. |
| */ |
| public static Pair<ByteString, Long> fromVirtualActionInput(VirtualActionInput input) |
| throws IOException { |
| CountingMD5OutputStream md5Stream = new CountingMD5OutputStream(); |
| input.writeTo(md5Stream); |
| ByteString digest = toByteString(md5Stream.getDigest()); |
| return Pair.of(digest, md5Stream.getSize()); |
| } |
| |
| /** |
| * A Sink that does an online MD5 calculation, which avoids forcing us to keep the entire |
| * proto message in memory. |
| */ |
| private static class MD5OutputStream extends OutputStream { |
| private final MessageDigest md = newBuilder(); |
| |
| @Override |
| public void write(int b) { |
| md.update((byte) b); |
| } |
| |
| @Override |
| public void write(byte[] b, int off, int len) { |
| md.update(b, off, len); |
| } |
| |
| public String getDigest() { |
| return BaseEncoding.base16().lowerCase().encode(md.digest()); |
| } |
| } |
| |
| private static final class CountingMD5OutputStream extends MD5OutputStream { |
| private long size; |
| |
| @Override |
| public void write(int b) { |
| super.write(b); |
| size++; |
| } |
| |
| @Override |
| public void write(byte[] b, int off, int len) { |
| super.write(b, off, len); |
| size += len; |
| } |
| |
| public long getSize() { |
| return size; |
| } |
| } |
| |
| /** |
| * @param digest the digest to check. |
| * @return true iff digest is a syntactically legal digest. It must be 32 |
| * characters of hex with lowercase letters. |
| */ |
| public static boolean isDigest(ByteString digest) { |
| if (digest == null || digest.size() != 32) { |
| return false; |
| } |
| |
| for (byte b : digest) { |
| char c = (char) b; |
| if ((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f')) { |
| continue; |
| } |
| return false; |
| } |
| return true; |
| } |
| |
| /** |
| * @param digest the digest. |
| * @return true iff the digest is that of an empty file. |
| */ |
| public static boolean isEmpty(ByteString digest) { |
| return digest.equals(EMPTY_DIGEST); |
| } |
| |
| /** |
| * @return a new MD5 digest builder. |
| */ |
| public static MessageDigest newBuilder() { |
| try { |
| return MessageDigest.getInstance("md5"); |
| } catch (NoSuchAlgorithmException e) { |
| throw new IllegalStateException("MD5 not available", e); |
| } |
| } |
| |
| /** |
| * Convert a String digest into a ByteString using ascii. |
| * @param digest the digest in ascii. |
| * @return the digest as a ByteString. |
| */ |
| public static ByteString toByteString(String digest) { |
| return ByteString.copyFrom(digest.getBytes(US_ASCII)); |
| } |
| } |