Check that DfsBlockCache#blockSize is a power of 2

In case a value is used which isn’t a power of 2 there will be a high
chance of java.lang.ArrayIndexOutBoundsException and
org.eclipse.jgit.errors.CorruptObjectException due to a mismatching
assumption for the DfsBlockCache#blockSizeShift parameter.

Change-Id: Ib348b3704edf10b5f93a3ffab4fa6f09cbbae231
Signed-off-by: Philipp Marx <smigfu@googlemail.com>

1 files changed, 88 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheConfigTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheConfigTest.java
new file mode 100644
index 0000000000..e612061abf
--- /dev/null
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/dfs/DfsBlockCacheConfigTest.java
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2016, Philipp Marx <philippmarx@gmx.de> and
+ * other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Distribution License v1.0 which accompanies this
+ * distribution, is reproduced below, and is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from this
+ * software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package org.eclipse.jgit.internal.storage.dfs;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+
+import org.eclipse.jgit.internal.JGitText;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+public class DfsBlockCacheConfigTest {
+
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
+
+	@Test
+	public void blockSizeNotPowerOfTwoExpectsException() {
+		thrown.expect(IllegalArgumentException.class);
+		thrown.expectMessage(is(JGitText.get().blockSizeNotPowerOf2));
+
+		new DfsBlockCacheConfig().setBlockSize(1000);
+	}
+
+	@Test
+	@SuppressWarnings("boxing")
+	public void negativeBlockSizeIsConvertedToDefault() {
+		DfsBlockCacheConfig config = new DfsBlockCacheConfig();
+		config.setBlockSize(-1);
+
+		assertThat(config.getBlockSize(), is(512));
+	}
+
+	@Test
+	@SuppressWarnings("boxing")
+	public void tooSmallBlockSizeIsConvertedToDefault() {
+		DfsBlockCacheConfig config = new DfsBlockCacheConfig();
+		config.setBlockSize(10);
+
+		assertThat(config.getBlockSize(), is(512));
+	}
+
+	@Test
+	@SuppressWarnings("boxing")
+	public void validBlockSize() {
+		DfsBlockCacheConfig config = new DfsBlockCacheConfig();
+		config.setBlockSize(65536);
+
+		assertThat(config.getBlockSize(), is(65536));
+	}
+}