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10 package org.eclipse.jgit.internal.storage.file;
11
12 import java.io.File;
13 import java.io.IOException;
14 import java.io.RandomAccessFile;
15
16 import org.eclipse.jgit.lib.AnyObjectId;
17 import org.eclipse.jgit.lib.ObjectId;
18 import org.eclipse.jgit.util.Equality;
19
20 class PackFileSnapshot extends FileSnapshot {
21
22 private static final ObjectId MISSING_CHECKSUM = ObjectId.zeroId();
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34 public static PackFileSnapshot save(File path) {
35 return new PackFileSnapshot(path);
36 }
37
38 private AnyObjectId checksum = MISSING_CHECKSUM;
39
40 private boolean wasChecksumChanged;
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42
43 PackFileSnapshot(File packFile) {
44 super(packFile);
45 }
46
47 void setChecksum(AnyObjectId checksum) {
48 this.checksum = checksum;
49 }
50
51
52 @Override
53 public boolean isModified(File packFile) {
54 if (!super.isModified(packFile)) {
55 return false;
56 }
57 if (wasSizeChanged() || wasFileKeyChanged()
58 || !wasLastModifiedRacilyClean()) {
59 return true;
60 }
61 return isChecksumChanged(packFile);
62 }
63
64 boolean isChecksumChanged(File packFile) {
65 return wasChecksumChanged = !Equality.isSameInstance(checksum,
66 MISSING_CHECKSUM)
67 && !checksum.equals(readChecksum(packFile));
68 }
69
70 private AnyObjectId readChecksum(File packFile) {
71 try (RandomAccessFile fd = new RandomAccessFile(packFile, "r")) {
72 fd.seek(fd.length() - 20);
73 final byte[] buf = new byte[20];
74 fd.readFully(buf, 0, 20);
75 return ObjectId.fromRaw(buf);
76 } catch (IOException e) {
77 return MISSING_CHECKSUM;
78 }
79 }
80
81 boolean wasChecksumChanged() {
82 return wasChecksumChanged;
83 }
84
85 @SuppressWarnings("nls")
86 @Override
87 public String toString() {
88 return "PackFileSnapshot [checksum=" + checksum + ", "
89 + super.toString() + "]";
90 }
91
92 }