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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.util.ConfigUtils;
28  import org.eclipse.aether.util.StringDigestUtil;
29  
30  import static java.util.Objects.requireNonNull;
31  
32  /**
33   * Wrapping {@link NameMapper}, that wraps another {@link NameMapper} and hashes resulting strings. It makes use of
34   * fact that (proper) Hash will create unique fixed length string for each different input string (so injection still
35   * stands). This mapper produces file system friendly names. Supports different "depths" (0-4 inclusive) where the
36   * name will contain 0 to 4 level deep directories.
37   * <p>
38   * This mapper is usable in any scenario, but intent was to produce more "compact" name mapper for file locking.
39   *
40   * @since 1.9.0
41   */
42  public class HashingNameMapper implements NameMapper {
43      /**
44       * The depth how many levels should adapter create. Acceptable values are 0-4 (inclusive).
45       *
46       * @configurationSource {@link RepositorySystemSession#getConfigProperties()}
47       * @configurationType {@link java.lang.Integer}
48       * @configurationDefaultValue {@link #DEFAULT_DEPTH}
49       */
50      public static final String CONFIG_PROP_DEPTH = NamedLockFactoryAdapter.CONFIG_PROPS_PREFIX + "hashing.depth";
51  
52      public static final int DEFAULT_DEPTH = 2;
53  
54      private final NameMapper delegate;
55  
56      public HashingNameMapper(final NameMapper delegate) {
57          this.delegate = requireNonNull(delegate);
58      }
59  
60      @Override
61      public boolean isFileSystemFriendly() {
62          return true; // hashes delegated strings, so whatever it wrapped, it does not come through
63      }
64  
65      @Override
66      public Collection<String> nameLocks(
67              RepositorySystemSession session,
68              Collection<? extends Artifact> artifacts,
69              Collection<? extends Metadata> metadatas) {
70          final int depth = ConfigUtils.getInteger(session, DEFAULT_DEPTH, CONFIG_PROP_DEPTH);
71          if (depth < 0 || depth > 4) {
72              throw new IllegalArgumentException("allowed depth value is between 0 and 4 (inclusive)");
73          }
74          return delegate.nameLocks(session, artifacts, metadatas).stream()
75                  .map(n -> hashName(n, depth))
76                  .collect(Collectors.toList());
77      }
78  
79      private String hashName(final String name, final int depth) {
80          String hashedName = StringDigestUtil.sha1(name);
81          if (depth == 0) {
82              return hashedName;
83          }
84          StringBuilder prefix = new StringBuilder();
85          int i = 0;
86          while (i < hashedName.length() && i / 2 < depth) {
87              prefix.append(hashedName, i, i + 2).append("/");
88              i += 2;
89          }
90          return prefix.append(hashedName).toString();
91      }
92  }