push: Report fatal server errors during pack writing

If the push client has requested side-band support the server can
signal a fatal error parsing the pack using the error channel (3)
and then hang up. This may cause the PackWriter to fail to write
data onto the network socket, which throws a misleading error back
up to the application and the user.

During a write failure poll the input to see if the side band system
can parse out an error message off channel 3. This should be fast as
there will either be an error present in the buffer, or the remote will
also have hung-up on the side band channel. In the case of a hang-up
just rethrow the original IOException as it's a network error.

Enable ignored PushConnectionTests this change is fixing.

Change-Id: Ie6ca43b39f3ef5727aba9251019e587006144376

Author: zakharovsergey1000

org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/PushConnectionTest.java

@@ -39,7 +39,6 @@
 import org.eclipse.jgit.lib.Repository;
 import org.junit.After;
 import org.junit.Before;
-import org.junit.Ignore;
 import org.junit.Test;
 
 public class PushConnectionTest {
@@ -155,7 +154,6 @@ public void invalidCommand() throws IOException {
 	}
 
 	@Test
-	@Ignore
 	public void limitCommandBytes() throws IOException {
 		Map<String, RemoteRefUpdate> updates = new HashMap<>();
 		for (int i = 0; i < 4; i++) {
@@ -181,7 +179,6 @@ public void limitCommandBytes() throws IOException {
 	}
 
 	@Test
-	@Ignore
 	public void limitPackSize() throws IOException {
 		// this maxPackSize leads to an unPackError
 		maxPackSize = 1;

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

@@ -172,38 +172,57 @@ protected TransportException noRepository(Throwable cause) {
 	 *             if any exception occurs.
 	 * @since 3.0
 	 */
+	@SuppressWarnings("Finally")
 	protected void doPush(final ProgressMonitor monitor,
 			final Map<String, RemoteRefUpdate> refUpdates,
 			OutputStream outputStream) throws TransportException {
+		Throwable suppressedThrowable = null;
 		try {
 			writeCommands(refUpdates.values(), monitor, outputStream);
 
 			if (pushOptions != null && capablePushOptions)
 				transmitOptions();
 			if (writePack)
 				writePack(refUpdates, monitor);
-			if (sentCommand) {
-				if (capableReport)
-					readStatusReport(refUpdates);
-				if (capableSideBand) {
-					// Ensure the data channel is at EOF, so we know we have
-					// read all side-band data from all channels and have a
-					// complete copy of the messages (if any) buffered from
-					// the other data channels.
-					//
-					int b = in.read();
-					if (0 <= b) {
-						throw new TransportException(uri, MessageFormat.format(
-								JGitText.get().expectedEOFReceived,
-								Character.valueOf((char) b)));
-					}
-				}
-			}
 		} catch (TransportException e) {
+			suppressedThrowable = e;
 			throw e;
 		} catch (Exception e) {
-			throw new TransportException(uri, e.getMessage(), e);
+			TransportException transportException = new TransportException(uri, e.getMessage(), e);
+			suppressedThrowable = transportException;
+			throw transportException;
 		} finally {
+			try {
+				if (sentCommand) {
+					if (capableReport) {
+						readStatusReport(refUpdates);
+					}
+					if (capableSideBand) {
+						// Ensure the data channel is at EOF, so we know we have
+						// read all side-band data from all channels and have a
+						// complete copy of the messages (if any) buffered from
+						// the other data channels.
+						//
+						int b = in.read();
+						if (0 <= b) {
+							throw new TransportException(uri, MessageFormat.format(
+									JGitText.get().expectedEOFReceived,
+									Character.valueOf((char) b)));
+						}
+					}
+				}
+			} catch (TransportException e) {
+				if (suppressedThrowable != null) {
+					e.addSuppressed(suppressedThrowable);
+				}
+				throw e;
+			} catch (Exception e) {
+				TransportException transportException = new TransportException(uri, e.getMessage(), e);
+				if (suppressedThrowable != null) {
+					transportException.addSuppressed(suppressedThrowable);
+				}
+				throw transportException;
+			}
 			if (in instanceof SideBandInputStream) {
 				((SideBandInputStream) in).drainMessages();
 			}