1 /*
2 * Copyright (C) 2019, Matthias Sohn <matthias.sohn@sap.com>
3 * and other copyright owners as documented in the project's IP log.
4 *
5 * This program and the accompanying materials are made available
6 * under the terms of the Eclipse Distribution License v1.0 which
7 * accompanies this distribution, is reproduced below, and is
8 * available at http://www.eclipse.org/org/documents/edl-v10.php
9 *
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or
13 * without modification, are permitted provided that the following
14 * conditions are met:
15 *
16 * - Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 *
19 * - Redistributions in binary form must reproduce the above
20 * copyright notice, this list of conditions and the following
21 * disclaimer in the documentation and/or other materials provided
22 * with the distribution.
23 *
24 * - Neither the name of the Eclipse Foundation, Inc. nor the
25 * names of its contributors may be used to endorse or promote
26 * products derived from this software without specific prior
27 * written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
30 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
31 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
34 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
37 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
38 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
41 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42 */
43 package org.eclipse.jgit.internal.storage.file;
44
45 import java.io.File;
46 import java.io.IOException;
47 import java.io.RandomAccessFile;
48
49 import org.eclipse.jgit.lib.AnyObjectId;
50 import org.eclipse.jgit.lib.ObjectId;
51
52 class PackFileSnapshot extends FileSnapshot {
53
54 private static final ObjectId MISSING_CHECKSUM = ObjectId.zeroId();
55
56 /**
57 * Record a snapshot for a specific packfile path.
58 * <p>
59 * This method should be invoked before the packfile is accessed.
60 *
61 * @param path
62 * the path to later remember. The path's current status
63 * information is saved.
64 * @return the snapshot.
65 */
66 public static PackFileSnapshot save(File path) {
67 return new PackFileSnapshot(path);
68 }
69
70 private AnyObjectId checksum = MISSING_CHECKSUM;
71
72 private boolean wasChecksumChanged;
73
74
75 PackFileSnapshot(File packFile) {
76 super(packFile);
77 }
78
79 void setChecksum(AnyObjectId checksum) {
80 this.checksum = checksum;
81 }
82
83 /** {@inheritDoc} */
84 @Override
85 public boolean isModified(File packFile) {
86 if (!super.isModified(packFile)) {
87 return false;
88 }
89 if (wasSizeChanged() || wasFileKeyChanged()
90 || !wasLastModifiedRacilyClean()) {
91 return true;
92 }
93 return isChecksumChanged(packFile);
94 }
95
96 boolean isChecksumChanged(File packFile) {
97 return wasChecksumChanged = checksum != MISSING_CHECKSUM
98 && !checksum.equals(readChecksum(packFile));
99 }
100
101 private AnyObjectId readChecksum(File packFile) {
102 try (RandomAccessFile fd = new RandomAccessFile(packFile, "r")) { //$NON-NLS-1$
103 fd.seek(fd.length() - 20);
104 final byte[] buf = new byte[20];
105 fd.readFully(buf, 0, 20);
106 return ObjectId.fromRaw(buf);
107 } catch (IOException e) {
108 return MISSING_CHECKSUM;
109 }
110 }
111
112 boolean wasChecksumChanged() {
113 return wasChecksumChanged;
114 }
115
116 @SuppressWarnings("nls")
117 @Override
118 public String toString() {
119 return "PackFileSnapshot [checksum=" + checksum + ", "
120 + super.toString() + "]";
121 }
122
123 }