Only mark packfile invalid if exception signals permanent problem

Add NoPackSignatureException and UnsupportedPackVersionException to
explicitly mark permanent unrecoverable problems with a pack 

Assume problem with a pack is permanent only if we are sure the
exception signals a non-transient problem we can't recover from:
- AccessDeniedException: we lack permissions
- CorruptObjectException: we detected corruption
- EOFException: file ended unexpectedly
- NoPackSignatureException: pack has no pack signature
- NoSuchFileException: file has gone missing
- PackMismatchException: pack no longer matches its index
- UnpackException: unpacking failed
- UnsupportedPackIndexVersionException: unsupported pack index version
- UnsupportedPackVersionException: unsupported pack version

Do not attempt to handle Errors since they are thrown for serious
problems applications should not try to recover from.

Change-Id: I2c416ce2b0e23255c4fb03a3f9a0ee237f7a484a
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/.settings/.api_filters

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<component id="org.eclipse.jgit" version="2">
+    <resource path="META-INF/MANIFEST.MF">
+        <filter comment="non-breaking addition of exception classes needed to cleanly fix error handling in PackFile" id="924844039">
+            <message_arguments>
+                <message_argument value="4.5.2"/>
+                <message_argument value="4.5.0"/>
+            </message_arguments>
+        </filter>
+    </resource>
+</component>

org.eclipse.jgit/src/org/eclipse/jgit/errors/NoPackSignatureException.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2017, Matthias Sohn <matthias.sohn@sap.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.errors;
+
+import java.io.IOException;
+
+/**
+ * Thrown when a PackFile is found not to contain the pack signature defined by
+ * git.
+ *
+ * @since 4.5
+ */
+public class NoPackSignatureException extends IOException {
+	private static final long serialVersionUID = 1L;
+
+	/**
+	 * Construct an exception.
+	 *
+	 * @param why
+	 *            description of the type of error.
+	 */
+	public NoPackSignatureException(final String why) {
+		super(why);
+	}
+}

org.eclipse.jgit/src/org/eclipse/jgit/errors/UnsupportedPackIndexVersionException.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2017, Matthias Sohn <matthias.sohn@sap.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.errors;
+
+import java.io.IOException;
+import java.text.MessageFormat;
+
+import org.eclipse.jgit.internal.JGitText;
+
+/**
+ * Thrown when a PackIndex uses an index version not supported by JGit.
+ *
+ * @since 4.5
+ */
+public class UnsupportedPackIndexVersionException extends IOException {
+	private static final long serialVersionUID = 1L;
+
+	/**
+	 * Construct an exception.
+	 *
+	 * @param version
+	 *            pack index version
+	 */
+	public UnsupportedPackIndexVersionException(final int version) {
+		super(MessageFormat.format(JGitText.get().unsupportedPackIndexVersion,
+				Integer.valueOf(version)));
+	}
+}

org.eclipse.jgit/src/org/eclipse/jgit/errors/UnsupportedPackVersionException.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2017, Matthias Sohn <matthias.sohn@sap.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.errors;
+
+import java.io.IOException;
+import java.text.MessageFormat;
+
+import org.eclipse.jgit.internal.JGitText;
+
+/**
+ * Thrown when a PackFile uses a pack version not supported by JGit.
+ *
+ * @since 4.5
+ */
+public class UnsupportedPackVersionException extends IOException {
+	private static final long serialVersionUID = 1L;
+
+	/**
+	 * Construct an exception.
+	 *
+	 * @param version
+	 *            pack version
+	 */
+	public UnsupportedPackVersionException(final long version) {
+		super(MessageFormat.format(JGitText.get().unsupportedPackVersion,
+				Long.valueOf(version)));
+	}
+}

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackFile.java

@@ -56,6 +56,8 @@ import java.io.InterruptedIOException;
 import java.io.RandomAccessFile;
 import java.nio.MappedByteBuffer;
 import java.nio.channels.FileChannel.MapMode;
+import java.nio.file.AccessDeniedException;
+import java.nio.file.NoSuchFileException;
 import java.text.MessageFormat;
 import java.util.Arrays;
 import java.util.Collections;
@@ -70,9 +72,13 @@ import java.util.zip.Inflater;
 import org.eclipse.jgit.errors.CorruptObjectException;
 import org.eclipse.jgit.errors.LargeObjectException;
 import org.eclipse.jgit.errors.MissingObjectException;
+import org.eclipse.jgit.errors.NoPackSignatureException;
 import org.eclipse.jgit.errors.PackInvalidException;
 import org.eclipse.jgit.errors.PackMismatchException;
 import org.eclipse.jgit.errors.StoredObjectRepresentationNotAvailableException;
+import org.eclipse.jgit.errors.UnpackException;
+import org.eclipse.jgit.errors.UnsupportedPackIndexVersionException;
+import org.eclipse.jgit.errors.UnsupportedPackVersionException;
 import org.eclipse.jgit.internal.JGitText;
 import org.eclipse.jgit.internal.storage.pack.BinaryDelta;
 import org.eclipse.jgit.internal.storage.pack.ObjectToPack;
@@ -642,15 +648,19 @@ public class PackFile implements Iterable<PackIndex.MutableEntry> {
 			// max open files)
 			openFail(!packFile.exists());
 			throw fn;
-		} catch (IOException ioe) {
+		} catch (EOFException | AccessDeniedException | NoSuchFileException
+				| CorruptObjectException | NoPackSignatureException
+				| PackMismatchException | UnpackException
+				| UnsupportedPackIndexVersionException
+				| UnsupportedPackVersionException pe) {
+			// exceptions signaling permanent problems with a pack
 			openFail(true);
-			throw ioe;
-		} catch (RuntimeException re) {
-			openFail(true);
-			throw re;
-		} catch (Error re) {
-			openFail(true);
-			throw re;
+			throw pe;
+		} catch (IOException | RuntimeException ge) {
+			// generic exceptions could be transient so we should not mark the
+			// pack invalid to avoid false MissingObjectExceptions
+			openFail(false);
+			throw ge;
 		}
 	}
 
@@ -717,29 +727,32 @@ public class PackFile implements Iterable<PackIndex.MutableEntry> {
 
 		fd.seek(0);
 		fd.readFully(buf, 0, 12);
-		if (RawParseUtils.match(buf, 0, Constants.PACK_SIGNATURE) != 4)
-			throw new IOException(JGitText.get().notAPACKFile);
+		if (RawParseUtils.match(buf, 0, Constants.PACK_SIGNATURE) != 4) {
+			throw new NoPackSignatureException(JGitText.get().notAPACKFile);
+		}
 		final long vers = NB.decodeUInt32(buf, 4);
 		final long packCnt = NB.decodeUInt32(buf, 8);
-		if (vers != 2 && vers != 3)
-			throw new IOException(MessageFormat.format(
-					JGitText.get().unsupportedPackVersion, Long.valueOf(vers)));
+		if (vers != 2 && vers != 3) {
+			throw new UnsupportedPackVersionException(vers);
+		}
 
-		if (packCnt != idx.getObjectCount())
+		if (packCnt != idx.getObjectCount()) {
 			throw new PackMismatchException(MessageFormat.format(
 					JGitText.get().packObjectCountMismatch,
 					Long.valueOf(packCnt), Long.valueOf(idx.getObjectCount()),
 					getPackFile()));
+		}
 
 		fd.seek(length - 20);
 		fd.readFully(buf, 0, 20);
-		if (!Arrays.equals(buf, packChecksum))
+		if (!Arrays.equals(buf, packChecksum)) {
 			throw new PackMismatchException(MessageFormat.format(
 					JGitText.get().packObjectCountMismatch
 					, ObjectId.fromRaw(buf).name()
 					, ObjectId.fromRaw(idx.packChecksum).name()
 					, getPackFile()));
 		}
+	}
 
 	ObjectLoader load(final WindowCursor curs, long pos)
 			throws IOException, LargeObjectException {

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/PackIndex.java

@@ -55,6 +55,7 @@ import java.util.Set;
 
 import org.eclipse.jgit.errors.CorruptObjectException;
 import org.eclipse.jgit.errors.MissingObjectException;
+import org.eclipse.jgit.errors.UnsupportedPackIndexVersionException;
 import org.eclipse.jgit.internal.JGitText;
 import org.eclipse.jgit.lib.AbbreviatedObjectId;
 import org.eclipse.jgit.lib.AnyObjectId;
@@ -138,9 +139,7 @@ public abstract class PackIndex
 			case 2:
 				return new PackIndexV2(fd);
 			default:
-				throw new IOException(MessageFormat.format(
-						JGitText.get().unsupportedPackIndexVersion,
-						Integer.valueOf(v)));
+				throw new UnsupportedPackIndexVersionException(v);
 			}
 		}
 		return new PackIndexV1(fd, hdr);