Remove validate support when reusing cached pack

Cached packs are only used when writing over the network or to
a bundle file and reuse validation is always disabled in these
two contexts. The client/consumer of the stream will be SHA-1
checksumming every object.

Reuse validation is most critical during local GC to avoid silently
ignoring corruption by stopping as soon as a problem is found and
leaving everything alone for the end-user to debug and salvage.
Cached packs are not supported during local GC as the bitmap rebuild
logic does not support including a cached pack in the result.

Strip out the validation and force PackWriter to always disable the
cached pack feature if reuseValidation is enabled.

Change-Id: If0d7baf2ae1bf1f7e71bf773151302c9f7887039

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsBlock.java

@@ -46,7 +46,6 @@
 package org.eclipse.jgit.internal.storage.dfs;
 
 import java.io.IOException;
-import java.security.MessageDigest;
 import java.util.zip.CRC32;
 import java.util.zip.DataFormatException;
 import java.util.zip.Inflater;
@@ -101,12 +100,9 @@ final class DfsBlock {
 		out.update(block, ptr, cnt);
 	}
 
-	void write(PackOutputStream out, long pos, int cnt, MessageDigest digest)
+	void write(PackOutputStream out, long pos, int cnt)
 			throws IOException {
-		int ptr = (int) (pos - start);
-		out.write(block, ptr, cnt);
-		if (digest != null)
-			digest.update(block, ptr, cnt);
+		out.write(block, (int) (pos - start), cnt);
 	}
 
 	void check(Inflater inf, byte[] tmp, long pos, int cnt)

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsCachedPack.java

@@ -78,8 +78,7 @@ public class DfsCachedPack extends CachedPack {
 		return ((DfsObjectRepresentation) rep).pack == pack;
 	}
 
-	void copyAsIs(PackOutputStream out, boolean validate, DfsReader ctx)
-			throws IOException {
-		pack.copyPackAsIs(out, validate, ctx);
+	void copyAsIs(PackOutputStream out, DfsReader ctx) throws IOException {
+		pack.copyPackAsIs(out, ctx);
 	}
 }

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java

@@ -56,9 +56,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.nio.ByteBuffer;
 import java.nio.channels.Channels;
-import java.security.MessageDigest;
 import java.text.MessageFormat;
-import java.util.Arrays;
 import java.util.Set;
 import java.util.zip.CRC32;
 import java.util.zip.DataFormatException;
@@ -466,55 +464,35 @@ public final class DfsPackFile {
 		return dstbuf;
 	}
 
-	void copyPackAsIs(PackOutputStream out, boolean validate, DfsReader ctx)
+	void copyPackAsIs(PackOutputStream out, DfsReader ctx)
 			throws IOException {
-		MessageDigest md = initCopyPack(out, validate, ctx);
-		long p;
-		if (cache.shouldCopyThroughCache(length))
-			p = copyPackThroughCache(out, ctx, md);
-		else
-			p = copyPackBypassCache(out, ctx, md);
-		verifyPackChecksum(p, md, ctx);
-	}
-
-	private MessageDigest initCopyPack(PackOutputStream out, boolean validate,
-			DfsReader ctx) throws IOException {
 		// If the length hasn't been determined yet, pin to set it.
-		if (length == -1)
+		if (length == -1) {
 			ctx.pin(this, 0);
-		if (!validate) {
 			ctx.unpin();
-			return null;
 		}
-
-		int hdrlen = 12;
-		byte[] buf = out.getCopyBuffer();
-		int n = ctx.copy(this, 0, buf, 0, hdrlen);
-		ctx.unpin();
-		if (n != hdrlen)
-			throw packfileIsTruncated();
-		MessageDigest md = Constants.newMessageDigest();
-		md.update(buf, 0, hdrlen);
-		return md;
+		if (cache.shouldCopyThroughCache(length))
+			copyPackThroughCache(out, ctx);
+		else
+			copyPackBypassCache(out, ctx);
 	}
 
-	private long copyPackThroughCache(PackOutputStream out, DfsReader ctx,
-			MessageDigest md) throws IOException {
+	private void copyPackThroughCache(PackOutputStream out, DfsReader ctx)
+			throws IOException {
 		long position = 12;
 		long remaining = length - (12 + 20);
 		while (0 < remaining) {
 			DfsBlock b = cache.getOrLoad(this, position, ctx);
 			int ptr = (int) (position - b.start);
 			int n = (int) Math.min(b.size() - ptr, remaining);
-			b.write(out, position, n, md);
+			b.write(out, position, n);
 			position += n;
 			remaining -= n;
 		}
-		return position;
 	}
 
-	private long copyPackBypassCache(PackOutputStream out, DfsReader ctx,
-			MessageDigest md) throws IOException {
+	private long copyPackBypassCache(PackOutputStream out, DfsReader ctx)
+			throws IOException {
 		try (ReadableChannel rc = ctx.db.openFile(packDesc, PACK)) {
 			ByteBuffer buf = newCopyBuffer(out, rc);
 			if (ctx.getOptions().getStreamPackBufferSize() > 0)
@@ -526,7 +504,7 @@ public final class DfsPackFile {
 				if (b != null) {
 					int ptr = (int) (position - b.start);
 					int n = (int) Math.min(b.size() - ptr, remaining);
-					b.write(out, position, n, md);
+					b.write(out, position, n);
 					position += n;
 					remaining -= n;
 					rc.position(position);
@@ -540,8 +518,6 @@ public final class DfsPackFile {
 				else if (n > remaining)
 					n = (int) remaining;
 				out.write(buf.array(), 0, n);
-				if (md != null)
-					md.update(buf.array(), 0, n);
 				position += n;
 				remaining -= n;
 			}
@@ -557,22 +533,6 @@ public final class DfsPackFile {
 		return ByteBuffer.wrap(copyBuf, 0, bs);
 	}
 
-	private void verifyPackChecksum(long position, MessageDigest md,
-			DfsReader ctx) throws IOException {
-		if (md != null) {
-			byte[] buf = new byte[20];
-			byte[] actHash = md.digest();
-			if (ctx.copy(this, position, buf, 0, 20) != 20)
-				throw packfileIsTruncated();
-			if (!Arrays.equals(actHash, buf)) {
-				invalid = true;
-				throw new IOException(MessageFormat.format(
-						JGitText.get().packfileCorruptionDetected,
-						getPackName()));
-			}
-		}
-	}
-
 	void copyAsIs(PackOutputStream out, DfsObjectToPack src,
 			boolean validate, DfsReader ctx) throws IOException,
 			StoredObjectRepresentationNotAvailableException {
@@ -719,7 +679,7 @@ public final class DfsPackFile {
 			// and we have it pinned.  Write this out without copying.
 			//
 			out.writeHeader(src, inflatedLength);
-			quickCopy.write(out, dataOffset, (int) dataLength, null);
+			quickCopy.write(out, dataOffset, (int) dataLength);
 
 		} else if (dataLength <= buf.length) {
 			// Tiny optimization: Lots of objects are very small deltas or

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsReader.java

@@ -492,9 +492,9 @@ public final class DfsReader extends ObjectReader implements ObjectReuseAsIs {
 			out.writeObject(otp);
 	}
 
-	public void copyPackAsIs(PackOutputStream out, CachedPack pack,
-			boolean validate) throws IOException {
-		((DfsCachedPack) pack).copyAsIs(out, validate, this);
+	public void copyPackAsIs(PackOutputStream out, CachedPack pack)
+			throws IOException {
+		((DfsCachedPack) pack).copyAsIs(out, this);
 	}
 
 	/**

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

@@ -46,7 +46,6 @@
 package org.eclipse.jgit.internal.storage.file;
 
 import java.io.IOException;
-import java.security.MessageDigest;
 import java.util.zip.CRC32;
 import java.util.zip.DataFormatException;
 import java.util.zip.Inflater;
@@ -84,12 +83,10 @@ final class ByteArrayWindow extends ByteWindow {
 	}
 
 	@Override
-	void write(PackOutputStream out, long pos, int cnt, MessageDigest digest)
+	void write(PackOutputStream out, long pos, int cnt)
 			throws IOException {
 		int ptr = (int) (pos - start);
 		out.write(array, ptr, cnt);
-		if (digest != null)
-			digest.update(array, ptr, cnt);
 	}
 
 	void check(Inflater inf, byte[] tmp, long pos, int cnt)

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

@@ -47,7 +47,6 @@ package org.eclipse.jgit.internal.storage.file;
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
-import java.security.MessageDigest;
 import java.util.zip.DataFormatException;
 import java.util.zip.Inflater;
 
@@ -76,7 +75,7 @@ final class ByteBufferWindow extends ByteWindow {
 	}
 
 	@Override
-	void write(PackOutputStream out, long pos, int cnt, MessageDigest digest)
+	void write(PackOutputStream out, long pos, int cnt)
 			throws IOException {
 		final ByteBuffer s = buffer.slice();
 		s.position((int) (pos - start));
@@ -86,8 +85,6 @@ final class ByteBufferWindow extends ByteWindow {
 			int n = Math.min(cnt, buf.length);
 			s.get(buf, 0, n);
 			out.write(buf, 0, n);
-			if (digest != null)
-				digest.update(buf, 0, n);
 			cnt -= n;
 		}
 	}

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

@@ -45,7 +45,6 @@
 package org.eclipse.jgit.internal.storage.file;
 
 import java.io.IOException;
-import java.security.MessageDigest;
 import java.util.zip.DataFormatException;
 import java.util.zip.Inflater;
 
@@ -121,8 +120,8 @@ abstract class ByteWindow {
 	 */
 	protected abstract int copy(int pos, byte[] dstbuf, int dstoff, int cnt);
 
-	abstract void write(PackOutputStream out, long pos, int cnt,
-			MessageDigest md) throws IOException;
+	abstract void write(PackOutputStream out, long pos, int cnt)
+			throws IOException;
 
 	final int setInput(long pos, Inflater inf) throws DataFormatException {
 		return setInput((int) (pos - start), inf);

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

@@ -79,10 +79,10 @@ class LocalCachedPack extends CachedPack {
 		return cnt;
 	}
 
-	void copyAsIs(PackOutputStream out, boolean validate, WindowCursor wc)
+	void copyAsIs(PackOutputStream out, WindowCursor wc)
 			throws IOException {
 		for (PackFile pack : getPacks())
-			pack.copyPackAsIs(out, validate, wc);
+			pack.copyPackAsIs(out, wc);
 	}
 
 	@Override

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

@@ -344,11 +344,11 @@ public class PackFile implements Iterable<PackIndex.MutableEntry> {
 		return dstbuf;
 	}
 
-	void copyPackAsIs(PackOutputStream out, boolean validate, WindowCursor curs)
+	void copyPackAsIs(PackOutputStream out, WindowCursor curs)
 			throws IOException {
 		// Pin the first window, this ensures the length is accurate.
 		curs.pin(this, 0);
-		curs.copyPackAsIs(this, length, validate, out);
+		curs.copyPackAsIs(this, length, out);
 	}
 
 	final void copyAsIs(PackOutputStream out, LocalObjectToPack src,
@@ -502,7 +502,7 @@ public class PackFile implements Iterable<PackIndex.MutableEntry> {
 			// and we have it pinned.  Write this out without copying.
 			//
 			out.writeHeader(src, inflatedLength);
-			quickCopy.write(out, dataOffset, (int) dataLength, null);
+			quickCopy.write(out, dataOffset, (int) dataLength);
 
 		} else if (dataLength <= buf.length) {
 			// Tiny optimization: Lots of objects are very small deltas or

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

@@ -45,9 +45,6 @@
 package org.eclipse.jgit.internal.storage.file;
 
 import java.io.IOException;
-import java.security.MessageDigest;
-import java.text.MessageFormat;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
@@ -59,7 +56,6 @@ import java.util.zip.Inflater;
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.errors.StoredObjectRepresentationNotAvailableException;
-import org.eclipse.jgit.internal.JGitText;
 import org.eclipse.jgit.internal.storage.pack.CachedPack;
 import org.eclipse.jgit.internal.storage.pack.ObjectReuseAsIs;
 import org.eclipse.jgit.internal.storage.pack.ObjectToPack;
@@ -232,27 +228,13 @@ final class WindowCursor extends ObjectReader implements ObjectReuseAsIs {
 		return cnt - need;
 	}
 
-	public void copyPackAsIs(PackOutputStream out, CachedPack pack,
-			boolean validate) throws IOException {
-		((LocalCachedPack) pack).copyAsIs(out, validate, this);
+	public void copyPackAsIs(PackOutputStream out, CachedPack pack)
+			throws IOException {
+		((LocalCachedPack) pack).copyAsIs(out, this);
 	}
 
-	void copyPackAsIs(final PackFile pack, final long length, boolean validate,
+	void copyPackAsIs(final PackFile pack, final long length,
 			final PackOutputStream out) throws IOException {
-		MessageDigest md = null;
-		if (validate) {
-			md = Constants.newMessageDigest();
-			byte[] buf = out.getCopyBuffer();
-			pin(pack, 0);
-			if (window.copy(0, buf, 0, 12) != 12) {
-				pack.setInvalid();
-				throw new IOException(MessageFormat.format(
-						JGitText.get().packfileIsTruncated, pack.getPackFile()
-								.getPath()));
-			}
-			md.update(buf, 0, 12);
-		}
-
 		long position = 12;
 		long remaining = length - (12 + 20);
 		while (0 < remaining) {
@@ -260,29 +242,10 @@ final class WindowCursor extends ObjectReader implements ObjectReuseAsIs {
 
 			int ptr = (int) (position - window.start);
 			int n = (int) Math.min(window.size() - ptr, remaining);
-			window.write(out, position, n, md);
+			window.write(out, position, n);
 			position += n;
 			remaining -= n;
 		}
-
-		if (md != null) {
-			byte[] buf = new byte[20];
-			byte[] actHash = md.digest();
-
-			pin(pack, position);
-			if (window.copy(position, buf, 0, 20) != 20) {
-				pack.setInvalid();
-				throw new IOException(MessageFormat.format(
-						JGitText.get().packfileIsTruncated, pack.getPackFile()
-								.getPath()));
-			}
-			if (!Arrays.equals(actHash, buf)) {
-				pack.setInvalid();
-				throw new IOException(MessageFormat.format(
-						JGitText.get().packfileCorruptionDetected, pack
-								.getPackFile().getPath()));
-			}
-		}
 	}
 
 	/**

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/ObjectReuseAsIs.java

@@ -209,16 +209,11 @@ public interface ObjectReuseAsIs {
 	 *            stream to append the pack onto.
 	 * @param pack
 	 *            the cached pack to send.
-	 * @param validate
-	 *            if true the representation must be validated and not be
-	 *            corrupt before being reused. If false, validation may be
-	 *            skipped as it will be performed elsewhere in the processing
-	 *            pipeline.
 	 * @throws IOException
 	 *             the pack cannot be read, or stream did not accept a write.
 	 */
-	public abstract void copyPackAsIs(PackOutputStream out, CachedPack pack,
-			boolean validate) throws IOException;
+	public abstract void copyPackAsIs(PackOutputStream out, CachedPack pack)
+			throws IOException;
 
 	/**
 	 * Obtain the available cached packs that match the bitmap and update

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/pack/PackWriter.java

@@ -1048,7 +1048,7 @@ public class PackWriter implements AutoCloseable {
 				stats.reusedObjects += pack.getObjectCount();
 				stats.reusedDeltas += deltaCnt;
 				stats.totalDeltas += deltaCnt;
-				reuseSupport.copyPackAsIs(out, pack, reuseValidate);
+				reuseSupport.copyPackAsIs(out, pack);
 			}
 			writeChecksum(out);
 			out.flush();
@@ -1866,7 +1866,7 @@ public class PackWriter implements AutoCloseable {
 				false);
 		BitmapBuilder needBitmap = wantBitmap.andNot(haveBitmap);
 
-		if (useCachedPacks && reuseSupport != null
+		if (useCachedPacks && reuseSupport != null && !reuseValidate
 				&& (excludeInPacks == null || excludeInPacks.length == 0))
 			cachedPacks.addAll(
 					reuseSupport.getCachedPacksAndUpdate(needBitmap));