ReceivePack: Enable side-band-64k capability for status reports

We now advertise the side-band-64k capability inside of ReceivePack,
allowing hooks to echo status messages down the side band channel
instead of over the optional stderr stream.

This change permits hooks running inside of an http:// based push
invocation to still message the end-user with more detailed errors
than the small per-command string in the status report.

Change-Id: I64f251ef2d13ab3fd0e1a319a4683725455e5244
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

org.eclipse.jgit/src/org/eclipse/jgit/transport/BasePackPushConnection.java

@@ -86,6 +86,8 @@ class BasePackPushConnection extends BasePackConnection implements
 
 	static final String CAPABILITY_OFS_DELTA = "ofs-delta";
 
+	static final String CAPABILITY_SIDE_BAND_64K = "side-band-64k";
+
 	private final boolean thinPack;
 
 	private boolean capableDeleteRefs;

org.eclipse.jgit/src/org/eclipse/jgit/transport/ReceivePack.java

@@ -43,13 +43,20 @@
 
 package org.eclipse.jgit.transport;
 
-import java.io.BufferedWriter;
+import static org.eclipse.jgit.transport.BasePackPushConnection.CAPABILITY_DELETE_REFS;
+import static org.eclipse.jgit.transport.BasePackPushConnection.CAPABILITY_OFS_DELTA;
+import static org.eclipse.jgit.transport.BasePackPushConnection.CAPABILITY_REPORT_STATUS;
+import static org.eclipse.jgit.transport.BasePackPushConnection.CAPABILITY_SIDE_BAND_64K;
+import static org.eclipse.jgit.transport.SideBandOutputStream.CH_DATA;
+import static org.eclipse.jgit.transport.SideBandOutputStream.CH_PROGRESS;
+import static org.eclipse.jgit.transport.SideBandOutputStream.MAX_BUF;
+
 import java.io.EOFException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.OutputStreamWriter;
-import java.io.PrintWriter;
+import java.io.Writer;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
@@ -84,12 +91,6 @@ import org.eclipse.jgit.util.io.TimeoutOutputStream;
  * Implements the server side of a push connection, receiving objects.
  */
 public class ReceivePack {
-	static final String CAPABILITY_REPORT_STATUS = BasePackPushConnection.CAPABILITY_REPORT_STATUS;
-
-	static final String CAPABILITY_DELETE_REFS = BasePackPushConnection.CAPABILITY_DELETE_REFS;
-
-	static final String CAPABILITY_OFS_DELTA = BasePackPushConnection.CAPABILITY_OFS_DELTA;
-
 	/** Database we write the stored objects into. */
 	private final Repository db;
 
@@ -151,7 +152,7 @@ public class ReceivePack {
 
 	private PacketLineOut pckOut;
 
-	private PrintWriter msgs;
+	private Writer msgs;
 
 	/** The refs we advertised as existing at the start of the connection. */
 	private Map<String, Ref> refs;
@@ -165,9 +166,12 @@ public class ReceivePack {
 	/** An exception caught while unpacking and fsck'ing the objects. */
 	private Throwable unpackError;
 
-	/** if {@link #enabledCapablities} has {@link #CAPABILITY_REPORT_STATUS} */
+	/** If {@link BasePackPushConnection#CAPABILITY_REPORT_STATUS} is enabled. */
 	private boolean reportStatus;
 
+	/** If {@link BasePackPushConnection#CAPABILITY_SIDE_BAND_64K} is enabled. */
+	private boolean sideBand;
+
 	/** Lock around the received pack file, while updating refs. */
 	private PackLock packLock;
 
@@ -440,7 +444,12 @@ public class ReceivePack {
 	 *            string must not end with an LF, and must not contain an LF.
 	 */
 	public void sendError(final String what) {
-		sendMessage("error", what);
+		try {
+			if (msgs != null)
+				msgs.write("error: " + what + "\n");
+		} catch (IOException e) {
+			// Ignore write failures.
+		}
 	}
 
 	/**
@@ -454,12 +463,12 @@ public class ReceivePack {
 	 *            string must not end with an LF, and must not contain an LF.
 	 */
 	public void sendMessage(final String what) {
-		sendMessage("remote", what);
-	}
-
-	private void sendMessage(final String type, final String what) {
+		try {
 			if (msgs != null)
-			msgs.println(type + ": " + what);
+				msgs.write(what + "\n");
+		} catch (IOException e) {
+			// Ignore write failures.
+		}
 	}
 
 	/**
@@ -499,16 +508,8 @@ public class ReceivePack {
 
 			pckIn = new PacketLineIn(rawIn);
 			pckOut = new PacketLineOut(rawOut);
-			if (messages != null) {
-				msgs = new PrintWriter(new BufferedWriter(
-						new OutputStreamWriter(messages, Constants.CHARSET),
-						8192)) {
-					@Override
-					public void println() {
-						print('\n');
-					}
-				};
-			}
+			if (messages != null)
+				msgs = new OutputStreamWriter(messages, Constants.CHARSET);
 
 			enabledCapablities = new HashSet<String>();
 			commands = new ArrayList<ReceiveCommand>();
@@ -516,8 +517,19 @@ public class ReceivePack {
 			service();
 		} finally {
 			try {
-				if (msgs != null) {
+				if (pckOut != null)
+					pckOut.flush();
+				if (msgs != null)
 					msgs.flush();
+
+				if (sideBand) {
+					// If we are using side band, we need to send a final
+					// flush-pkt to tell the remote peer the side band is
+					// complete and it should stop decoding. We need to
+					// use the original output stream as rawOut is now the
+					// side band data channel.
+					//
+					new PacketLineOut(output).end();
 				}
 			} finally {
 				unlockPack();
@@ -581,10 +593,9 @@ public class ReceivePack {
 			} else if (msgs != null) {
 				sendStatusReport(false, new Reporter() {
 					void sendString(final String s) throws IOException {
-						msgs.println(s);
+						msgs.write(s + "\n");
 					}
 				});
-				msgs.flush();
 			}
 
 			postReceive.onPostReceive(this, filterCommands(Result.OK));
@@ -609,6 +620,7 @@ public class ReceivePack {
 	public void sendAdvertisedRefs(final RefAdvertiser adv) throws IOException {
 		final RevFlag advertised = walk.newFlag("ADVERTISED");
 		adv.init(walk, advertised);
+		adv.advertiseCapability(CAPABILITY_SIDE_BAND_64K);
 		adv.advertiseCapability(CAPABILITY_DELETE_REFS);
 		adv.advertiseCapability(CAPABILITY_REPORT_STATUS);
 		if (allowOfsDelta)
@@ -667,6 +679,16 @@ public class ReceivePack {
 
 	private void enableCapabilities() {
 		reportStatus = enabledCapablities.contains(CAPABILITY_REPORT_STATUS);
+
+		sideBand = enabledCapablities.contains(CAPABILITY_SIDE_BAND_64K);
+		if (sideBand) {
+			OutputStream out = rawOut;
+
+			rawOut = new SideBandOutputStream(CH_DATA, MAX_BUF, out);
+			pckOut = new PacketLineOut(rawOut);
+			msgs = new OutputStreamWriter(new SideBandOutputStream(CH_PROGRESS,
+					MAX_BUF, out), Constants.CHARSET);
+		}
 	}
 
 	private boolean needPack() {