Add SilentFileInputStream to allow ignoring exceptions raised by close()

There are several cases where a FileInputStream is opened outside of
a try-with-resource because we want to explicitly close it and ignore
any IOException that is raised by the close() method.

Introduce a helper class, SilentFileInputStream, that overrides the
close method and ignores the exceptions. This allows to open the stream
in a try-with-resource block and remove the explicit handling of the
close method.

Change-Id: I8612f948a1a5b3d1031344922ad75ce4492cfc61
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

5 files changed, 98 insertions, 55 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCache.java b/org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCache.java
index cc431dbdf2..fcee252f80 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCache.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCache.java
@@ -49,7 +49,6 @@ 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;
@@ -87,6 +86,7 @@ import org.eclipse.jgit.util.IO;
 import org.eclipse.jgit.util.MutableInteger;
 import org.eclipse.jgit.util.NB;
 import org.eclipse.jgit.util.TemporaryBuffer;
+import org.eclipse.jgit.util.io.SilentFileInputStream;
 
 /**
  * Support for the Git dircache (aka index file).
@@ -429,18 +429,10 @@ public class DirCache {
 		if (!liveFile.exists())
 			clear();
 		else if (snapshot == null || snapshot.isModified(liveFile)) {
-			try {
-				final FileInputStream inStream = new FileInputStream(liveFile);
-				try {
-					clear();
-					readFrom(inStream);
-				} finally {
-					try {
-						inStream.close();
-					} catch (IOException err2) {
-						// Ignore any close failures.
-					}
-				}
+			try (SilentFileInputStream inStream = new SilentFileInputStream(
+					liveFile)) {
+				clear();
+				readFrom(inStream);
 			} catch (FileNotFoundException fnfe) {
 				if (liveFile.exists()) {
 					// Panic: the index file exists but we can't read it
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndex.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndex.java
index 21a1c7fcb3..6772e2c905 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndex.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackBitmapIndex.java
@@ -44,7 +44,6 @@
 package org.eclipse.jgit.internal.storage.file;
 
 import java.io.File;
-import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.text.MessageFormat;
@@ -53,6 +52,7 @@ import org.eclipse.jgit.errors.CorruptObjectException;
 import org.eclipse.jgit.internal.JGitText;
 import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.util.io.SilentFileInputStream;
 
 import com.googlecode.javaewah.EWAHCompressedBitmap;
 
@@ -93,19 +93,15 @@ public abstract class PackBitmapIndex {
 	public static PackBitmapIndex open(
 			File idxFile, PackIndex packIndex, PackReverseIndex reverseIndex)
 			throws IOException {
-		final FileInputStream fd = new FileInputStream(idxFile);
-		try {
-			return read(fd, packIndex, reverseIndex);
-		} catch (IOException ioe) {
-			throw new IOException(MessageFormat
-					.format(JGitText.get().unreadablePackIndex,
-							idxFile.getAbsolutePath()),
-					ioe);
-		} finally {
+		try (SilentFileInputStream fd = new SilentFileInputStream(
+				idxFile)) {
 			try {
-				fd.close();
-			} catch (IOException err2) {
-				// ignore
+				return read(fd, packIndex, reverseIndex);
+			} catch (IOException ioe) {
+				throw new IOException(
+						MessageFormat.format(JGitText.get().unreadablePackIndex,
+								idxFile.getAbsolutePath()),
+						ioe);
 			}
 		}
 	}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackIndex.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackIndex.java
index acfd9c4719..e324c1f52b 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackIndex.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackIndex.java
@@ -45,7 +45,6 @@
 package org.eclipse.jgit.internal.storage.file;
 
 import java.io.File;
-import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
@@ -64,6 +63,7 @@ import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectIdSet;
 import org.eclipse.jgit.util.IO;
 import org.eclipse.jgit.util.NB;
+import org.eclipse.jgit.util.io.SilentFileInputStream;
 
 /**
  * Access path to locate objects by {@link org.eclipse.jgit.lib.ObjectId} in a
@@ -95,20 +95,14 @@ public abstract class PackIndex
 	 *             unrecognized data version, or unexpected data corruption.
 	 */
 	public static PackIndex open(final File idxFile) throws IOException {
-		final FileInputStream fd = new FileInputStream(idxFile);
-		try {
-			return read(fd);
+		try (SilentFileInputStream fd = new SilentFileInputStream(
+				idxFile)) {
+				return read(fd);
 		} catch (IOException ioe) {
-			throw new IOException(MessageFormat
-					.format(JGitText.get().unreadablePackIndex,
+			throw new IOException(
+					MessageFormat.format(JGitText.get().unreadablePackIndex,
 							idxFile.getAbsolutePath()),
 					ioe);
-		} finally {
-			try {
-				fd.close();
-			} catch (IOException err2) {
-				// ignore
-			}
 		}
 	}
 
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/IO.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/IO.java
index f39d217863..fa19e89f2e 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/util/IO.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/IO.java
@@ -47,7 +47,6 @@ package org.eclipse.jgit.util;
 
 import java.io.EOFException;
 import java.io.File;
-import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
@@ -59,6 +58,7 @@ import java.util.ArrayList;
 import java.util.List;
 
 import org.eclipse.jgit.internal.JGitText;
+import org.eclipse.jgit.util.io.SilentFileInputStream;
 
 /**
  * Input/Output utilities
@@ -98,8 +98,7 @@ public class IO {
 	 */
 	public static final byte[] readSome(final File path, final int limit)
 			throws FileNotFoundException, IOException {
-		FileInputStream in = new FileInputStream(path);
-		try {
+		try (SilentFileInputStream in = new SilentFileInputStream(path)) {
 			byte[] buf = new byte[limit];
 			int cnt = 0;
 			for (;;) {
@@ -113,12 +112,6 @@ public class IO {
 			byte[] res = new byte[cnt];
 			System.arraycopy(buf, 0, res, 0, cnt);
 			return res;
-		} finally {
-			try {
-				in.close();
-			} catch (IOException ignored) {
-				// do nothing
-			}
 		}
 	}
 
@@ -138,8 +131,7 @@ public class IO {
 	 */
 	public static final byte[] readFully(final File path, final int max)
 			throws FileNotFoundException, IOException {
-		final FileInputStream in = new FileInputStream(path);
-		try {
+		try (SilentFileInputStream in = new SilentFileInputStream(path)) {
 			long sz = Math.max(path.length(), 1);
 			if (sz > max)
 				throw new IOException(MessageFormat.format(
@@ -173,12 +165,6 @@ public class IO {
 				buf = nb;
 			}
 			return buf;
-		} finally {
-			try {
-				in.close();
-			} catch (IOException ignored) {
-				// ignore any close errors, this was a read only stream
-			}
 		}
 	}
 
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/io/SilentFileInputStream.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/io/SilentFileInputStream.java
new file mode 100644
index 0000000000..e58803bb9b
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/io/SilentFileInputStream.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2018, David Pursehouse <david.pursehouse@gmail.com>
+ * 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.util.io;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+/**
+ * An implementation of FileInputStream that ignores any exceptions on close().
+ *
+ * @since 5.0
+ */
+public class SilentFileInputStream extends FileInputStream {
+	/**
+	 * @param file
+	 *            the file
+	 * @throws FileNotFoundException
+	 *             the file was not found
+	 */
+	public SilentFileInputStream(File file) throws FileNotFoundException {
+		super(file);
+	}
+
+	@Override
+	public void close() {
+		try {
+			super.close();
+		} catch (IOException e) {
+			// Ignore
+		}
+	}
+}