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1   /*
2    * Copyright (C) 2015, Matthias Sohn <matthias.sohn@sap.com> and others
3    *
4    * This program and the accompanying materials are made available under the
5    * terms of the Eclipse Distribution License v. 1.0 which is available at
6    * https://www.eclipse.org/org/documents/edl-v10.php.
7    *
8    * SPDX-License-Identifier: BSD-3-Clause
9    */
10  package org.eclipse.jgit.lfs.internal;
11  
12  import java.io.IOException;
13  import java.io.OutputStream;
14  import java.nio.file.Path;
15  import java.security.DigestOutputStream;
16  import java.text.MessageFormat;
17  
18  import org.eclipse.jgit.annotations.Nullable;
19  import org.eclipse.jgit.internal.storage.file.LockFile;
20  import org.eclipse.jgit.lfs.errors.CorruptLongObjectException;
21  import org.eclipse.jgit.lfs.lib.AnyLongObjectId;
22  import org.eclipse.jgit.lfs.lib.Constants;
23  import org.eclipse.jgit.lfs.lib.LongObjectId;
24  
25  /**
26   * Output stream writing content to a
27   * {@link org.eclipse.jgit.internal.storage.file.LockFile} which is committed on
28   * close(). The stream checks if the hash of the stream content matches the id.
29   */
30  public class AtomicObjectOutputStream extends OutputStream {
31  
32  	private LockFile locked;
33  
34  	private DigestOutputStream out;
35  
36  	private boolean aborted;
37  
38  	private AnyLongObjectId id;
39  
40  	/**
41  	 * Constructor for AtomicObjectOutputStream.
42  	 *
43  	 * @param path
44  	 *            a {@link java.nio.file.Path} object.
45  	 * @param id
46  	 *            a {@link org.eclipse.jgit.lfs.lib.AnyLongObjectId} object.
47  	 * @throws java.io.IOException
48  	 */
49  	public AtomicObjectOutputStream(Path path, AnyLongObjectId id)
50  			throws IOException {
51  		locked = new LockFile(path.toFile());
52  		locked.lock();
53  		this.id = id;
54  		out = new DigestOutputStream(locked.getOutputStream(),
55  				Constants.newMessageDigest());
56  	}
57  
58  	/**
59  	 * Constructor for AtomicObjectOutputStream.
60  	 *
61  	 * @param path
62  	 *            a {@link java.nio.file.Path} object.
63  	 * @throws java.io.IOException
64  	 */
65  	public AtomicObjectOutputStream(Path path) throws IOException {
66  		this(path, null);
67  	}
68  
69  	/**
70  	 * Get the <code>id</code>.
71  	 *
72  	 * @return content hash of the object which was streamed through this
73  	 *         stream. May return {@code null} if called before closing this
74  	 *         stream.
75  	 */
76  	@Nullable
77  	public AnyLongObjectId getId() {
78  		return id;
79  	}
80  
81  	/** {@inheritDoc} */
82  	@Override
83  	public void write(int b) throws IOException {
84  		out.write(b);
85  	}
86  
87  	/** {@inheritDoc} */
88  	@Override
89  	public void write(byte[] b) throws IOException {
90  		out.write(b);
91  	}
92  
93  	/** {@inheritDoc} */
94  	@Override
95  	public void write(byte[] b, int off, int len) throws IOException {
96  		out.write(b, off, len);
97  	}
98  
99  	/** {@inheritDoc} */
100 	@Override
101 	public void close() throws IOException {
102 		out.close();
103 		if (!aborted) {
104 			if (id != null) {
105 				verifyHash();
106 			} else {
107 				id = LongObjectId.fromRaw(out.getMessageDigest().digest());
108 			}
109 			locked.commit();
110 		}
111 	}
112 
113 	private void verifyHash() {
114 		AnyLongObjectId contentHash = LongObjectId
115 				.fromRaw(out.getMessageDigest().digest());
116 		if (!contentHash.equals(id)) {
117 			abort();
118 			throw new CorruptLongObjectException(id, contentHash,
119 					MessageFormat.format(LfsText.get().corruptLongObject,
120 							contentHash, id));
121 		}
122 	}
123 
124 	/**
125 	 * Aborts the stream. Temporary file will be deleted
126 	 */
127 	public void abort() {
128 		locked.unlock();
129 		aborted = true;
130 	}
131 }