com.facebook.buck.util.cache.JarContentHasher.java Source code

Introduction

Here is the source code for com.facebook.buck.util.cache.JarContentHasher.java

Source

/*
 * Copyright 2016-present Facebook, Inc.
 *
 * 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.facebook.buck.util.cache;

import com.facebook.buck.io.HashingDeterministicJarWriter;
import com.facebook.buck.io.ProjectFilesystem;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import com.google.common.hash.HashCode;

import java.io.IOException;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Map;
import java.util.jar.Attributes;
import java.util.jar.Manifest;

public class JarContentHasher {

    private final ProjectFilesystem filesystem;
    private final Path jarRelativePath;

    public JarContentHasher(ProjectFilesystem filesystem, Path jarRelativePath) {
        Preconditions.checkState(!jarRelativePath.isAbsolute());
        this.filesystem = filesystem;
        this.jarRelativePath = jarRelativePath;
    }

    public Path getJarRelativePath() {
        return jarRelativePath;
    }

    public ImmutableMap<Path, HashCodeAndFileType> getContentHashes() throws IOException {
        Manifest manifest = filesystem.getJarManifest(jarRelativePath);
        if (manifest == null) {
            throw new UnsupportedOperationException(
                    "Cache does not know how to return hash codes for archive members except "
                            + "when the archive contains a META-INF/MANIFEST.MF with "
                            + HashingDeterministicJarWriter.DIGEST_ATTRIBUTE_NAME + " attributes for each file.");
        }

        ImmutableMap.Builder<Path, HashCodeAndFileType> builder = ImmutableMap.builder();
        for (Map.Entry<String, Attributes> nameAttributesEntry : manifest.getEntries().entrySet()) {
            Path memberPath = Paths.get(nameAttributesEntry.getKey());
            Attributes attributes = nameAttributesEntry.getValue();
            String hashStringValue = attributes.getValue(HashingDeterministicJarWriter.DIGEST_ATTRIBUTE_NAME);
            if (hashStringValue == null) {
                continue;
            }

            HashCode memberHash = HashCode.fromString(hashStringValue);
            HashCodeAndFileType memberHashCodeAndFileType = HashCodeAndFileType.ofFile(memberHash);

            builder.put(memberPath, memberHashCodeAndFileType);
        }

        return builder.build();
    }
}