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Correctly skip over unrecognized optional dircache extensions

We didn't skip the correct number of bytes when we skipped over an
unrecognized but optional dircache extension.  We missed skipping
the 8 byte header that makes up the extension's name and length.

We also didn't include the skipped extension's payload as part of
our index checksum, resuting in a checksum failure when the index
was done reading.  So ensure we always scan through a skipped
section and include it in the checksum computation.

Add a test case for a currently unsupported index extension, 'ZZZZ',
to verify we can still read the DirCache object even though we
don't know what 'ZZZZ' is supposed to mean.

Bug: 301287
Change-Id: I4bdde94576fffe826d0782483fd98cab1ea628fa
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
stable-0.7
Shawn O. Pearce 15 years ago
parent
commit
784b24dde1
  1. BIN
      org.eclipse.jgit.test/tst-rsrc/org/eclipse/jgit/test/resources/gitgit.index.ZZZZ
  2. BIN
      org.eclipse.jgit.test/tst-rsrc/org/eclipse/jgit/test/resources/gitgit.index.aaaa
  3. BIN
      org.eclipse.jgit.test/tst-rsrc/org/eclipse/jgit/test/resources/gitgit.index.badchecksum
  4. 29
      org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheCGitCompatabilityTest.java
  5. 52
      org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCache.java

BIN
org.eclipse.jgit.test/tst-rsrc/org/eclipse/jgit/test/resources/gitgit.index.ZZZZ

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BIN
org.eclipse.jgit.test/tst-rsrc/org/eclipse/jgit/test/resources/gitgit.index.aaaa

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BIN
org.eclipse.jgit.test/tst-rsrc/org/eclipse/jgit/test/resources/gitgit.index.badchecksum

Binary file not shown.

29
org.eclipse.jgit.test/tst/org/eclipse/jgit/dircache/DirCacheCGitCompatabilityTest.java vendored

@ -52,6 +52,7 @@ import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import org.eclipse.jgit.errors.CorruptObjectException;
import org.eclipse.jgit.junit.LocalDiskRepositoryTestCase;
import org.eclipse.jgit.lib.FileMode;
import org.eclipse.jgit.lib.ObjectId;
@ -100,6 +101,34 @@ public class DirCacheCGitCompatabilityTest extends LocalDiskRepositoryTestCase {
}
}
public void testUnsupportedOptionalExtension() throws Exception {
final DirCache dc = new DirCache(pathOf("gitgit.index.ZZZZ"));
dc.read();
assertEquals(1, dc.getEntryCount());
assertEquals("A", dc.getEntry(0).getPathString());
}
public void testUnsupportedRequiredExtension() throws Exception {
final DirCache dc = new DirCache(pathOf("gitgit.index.aaaa"));
try {
dc.read();
fail("Cache loaded an unsupported extension");
} catch (CorruptObjectException err) {
assertEquals("DIRC extension 'aaaa'"
+ " not supported by this version.", err.getMessage());
}
}
public void testCorruptChecksumAtFooter() throws Exception {
final DirCache dc = new DirCache(pathOf("gitgit.index.badchecksum"));
try {
dc.read();
fail("Cache loaded despite corrupt checksum");
} catch (CorruptObjectException err) {
assertEquals("DIRC checksum mismatch", err.getMessage());
}
}
private static void assertEqual(final CGitIndexRecord c,
final DirCacheEntry j) {
assertNotNull(c);

52
org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCache.java vendored

@ -1,5 +1,5 @@
/*
* Copyright (C) 2008-2009, Google Inc.
* Copyright (C) 2008-2010, Google Inc.
* Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
* and other copyright owners as documented in the project's IP log.
*
@ -46,12 +46,14 @@ package org.eclipse.jgit.dircache;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.io.UnsupportedEncodingException;
import java.security.DigestOutputStream;
import java.security.MessageDigest;
import java.util.Arrays;
@ -387,13 +389,20 @@ public class DirCache {
//
break;
}
in.reset();
md.update(hdr, 0, 8);
IO.skipFully(in, 8);
long sz = NB.decodeUInt32(hdr, 4);
switch (NB.decodeInt32(hdr, 0)) {
case EXT_TREE: {
final byte[] raw = new byte[NB.decodeInt32(hdr, 4)];
md.update(hdr, 0, 8);
IO.skipFully(in, 8);
if (Integer.MAX_VALUE < sz) {
throw new CorruptObjectException("DIRC extension "
+ formatExtensionName(hdr) + " is too large at "
+ sz + " bytes.");
}
final byte[] raw = new byte[(int) sz];
IO.readFully(in, raw, 0, raw.length);
md.update(raw, 0, raw.length);
tree = new DirCacheTree(raw, new MutableInteger(), null);
@ -403,18 +412,18 @@ public class DirCache {
if (hdr[0] >= 'A' && hdr[0] <= 'Z') {
// The extension is optional and is here only as
// a performance optimization. Since we do not
// understand it, we can safely skip past it.
// understand it, we can safely skip past it, after
// we include its data in our checksum.
//
IO.skipFully(in, NB.decodeUInt32(hdr, 4));
skipOptionalExtension(in, md, hdr, sz);
} else {
// The extension is not an optimization and is
// _required_ to understand this index format.
// Since we did not trap it above we must abort.
//
throw new CorruptObjectException("DIRC extension '"
+ Constants.CHARSET.decode(
ByteBuffer.wrap(hdr, 0, 4)).toString()
+ "' not supported by this version.");
throw new CorruptObjectException("DIRC extension "
+ formatExtensionName(hdr)
+ " not supported by this version.");
}
}
}
@ -425,6 +434,27 @@ public class DirCache {
}
}
private void skipOptionalExtension(final InputStream in,
final MessageDigest md, final byte[] hdr, long sz)
throws IOException {
final byte[] b = new byte[4096];
while (0 < sz) {
int n = in.read(b, 0, (int) Math.min(b.length, sz));
if (n < 0) {
throw new EOFException("Short read of optional DIRC extension "
+ formatExtensionName(hdr) + "; expected another " + sz
+ " bytes within the section.");
}
md.update(b, 0, n);
sz -= n;
}
}
private static String formatExtensionName(final byte[] hdr)
throws UnsupportedEncodingException {
return "'" + new String(hdr, 0, 4, "ISO-8859-1") + "'";
}
private static boolean is_DIRC(final byte[] hdr) {
if (hdr.length < SIG_DIRC.length)
return false;

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