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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *   http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.eclipse.aether.internal.impl.synccontext.named;
20  
21  import java.util.Collection;
22  import java.util.stream.Collectors;
23  
24  import org.eclipse.aether.RepositorySystemSession;
25  import org.eclipse.aether.artifact.Artifact;
26  import org.eclipse.aether.metadata.Metadata;
27  import org.eclipse.aether.named.NamedLockKey;
28  import org.eclipse.aether.util.ConfigUtils;
29  import org.eclipse.aether.util.StringDigestUtil;
30  
31  import static java.util.Objects.requireNonNull;
32  
33  /**
34   * Wrapping {@link NameMapper}, that wraps another {@link NameMapper} and hashes resulting strings. It makes use of
35   * fact that (proper) Hash will create unique fixed length string for each different input string (so injection still
36   * stands). This mapper produces file system friendly names. Supports different "depths" (0-4 inclusive) where the
37   * name will contain 0 to 4 level deep directories.
38   * <p>
39   * This mapper is usable in any scenario, but intent was to produce more "compact" name mapper for file locking.
40   *
41   * @since 1.9.0
42   */
43  public class HashingNameMapper implements NameMapper {
44      /**
45       * The depth how many levels should adapter create. Acceptable values are 0-4 (inclusive).
46       *
47       * @configurationSource {@link RepositorySystemSession#getConfigProperties()}
48       * @configurationType {@link java.lang.Integer}
49       * @configurationDefaultValue {@link #DEFAULT_DEPTH}
50       */
51      public static final String CONFIG_PROP_DEPTH = NamedLockFactoryAdapter.CONFIG_PROPS_PREFIX + "hashing.depth";
52  
53      public static final int DEFAULT_DEPTH = 2;
54  
55      private final NameMapper delegate;
56  
57      public HashingNameMapper(final NameMapper delegate) {
58          this.delegate = requireNonNull(delegate);
59      }
60  
61      @Override
62      public boolean isFileSystemFriendly() {
63          return true; // hashes delegated strings, so whatever it wrapped, it does not come through
64      }
65  
66      @Override
67      public Collection<NamedLockKey> nameLocks(
68              RepositorySystemSession session,
69              Collection<? extends Artifact> artifacts,
70              Collection<? extends Metadata> metadatas) {
71          final int depth = ConfigUtils.getInteger(session, DEFAULT_DEPTH, CONFIG_PROP_DEPTH);
72          if (depth < 0 || depth > 4) {
73              throw new IllegalArgumentException("allowed depth value is between 0 and 4 (inclusive)");
74          }
75          return delegate.nameLocks(session, artifacts, metadatas).stream()
76                  .map(k -> NamedLockKey.of(hashName(k.name(), depth), k.resources()))
77                  .collect(Collectors.toList());
78      }
79  
80      private String hashName(final String name, final int depth) {
81          String hashedName = StringDigestUtil.sha1(name);
82          if (depth == 0) {
83              return hashedName;
84          }
85          StringBuilder prefix = new StringBuilder();
86          int i = 0;
87          while (i < hashedName.length() && i / 2 < depth) {
88              prefix.append(hashedName, i, i + 2).append("/");
89              i += 2;
90          }
91          return prefix.append(hashedName).toString();
92      }
93  }