Abstract SSH setup to support GIT_SSH

In order to honor GIT_SSH the TransportGitSsh class needs to run the
process named by the GIT_SSH environment variable and use that as the
pipes for connectivity to the remote peer.  Refactor the current
transport code to support a different type of pipe connectivity, so we
can later add GIT_SSH.

Bug: 321062
Change-Id: I9d8ee1a95f1bac5013b33a4a42dcf1f98f92172f
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

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

@@ -97,12 +97,16 @@ static boolean canHandle(final URIish uri) {
 
 	@Override
 	public FetchConnection openFetch() throws TransportException {
-		return new SshFetchConnection();
+		return new SshFetchConnection(newConnection());
 	}
 
 	@Override
 	public PushConnection openPush() throws TransportException {
-		return new SshPushConnection();
+		return new SshPushConnection(newConnection());
+	}
+
+	private Connection newConnection() {
+		return new JschConnection();
 	}
 
 	private static void sqMinimal(final StringBuilder cmd, final String val) {
@@ -128,7 +132,7 @@ private static void sq(final StringBuilder cmd, final String val) {
 			cmd.append(QuotedString.BOURNE.quote(val));
 	}
 
-	private String commandFor(final String exe) {
+	String commandFor(final String exe) {
 		String path = uri.getPath();
 		if (uri.getScheme() != null && uri.getPath().startsWith("/~"))
 			path = (uri.getPath().substring(1));
@@ -146,28 +150,6 @@ private String commandFor(final String exe) {
 		return cmd.toString();
 	}
 
-	ChannelExec exec(final String exe) throws TransportException {
-		initSession();
-
-		try {
-			final ChannelExec channel = (ChannelExec) sock.openChannel("exec");
-			channel.setCommand(commandFor(exe));
-			return channel;
-		} catch (JSchException je) {
-			throw new TransportException(uri, je.getMessage(), je);
-		}
-	}
-
-	private void connect(ChannelExec channel) throws TransportException {
-		try {
-			channel.connect(getTimeout() > 0 ? getTimeout() * 1000 : 0);
-			if (!channel.isConnected())
-				throw new TransportException(uri, "connection failed");
-		} catch (JSchException e) {
-			throw new TransportException(uri, e.getMessage(), e);
-		}
-	}
-
 	void checkExecFailure(int status, String exe, String why)
 			throws TransportException {
 		if (status == 127) {
@@ -198,60 +180,132 @@ NoRemoteRepositoryException cleanNotFound(NoRemoteRepositoryException nf,
 		return new NoRemoteRepositoryException(uri, why);
 	}
 
-	// JSch won't let us interrupt writes when we use our InterruptTimer to
+	private abstract class Connection {
-	// break out of a long-running write operation. To work around that we
+		abstract void exec(String commandName) throws TransportException;
-	// spawn a background thread to shuttle data through a pipe, as we can
+
-	// issue an interrupted write out of that. Its slower, so we only use
+		abstract void connect() throws TransportException;
-	// this route if there is a timeout.
+
+		abstract InputStream getInputStream() throws IOException;
+
+		abstract OutputStream getOutputStream() throws IOException;
+
+		abstract InputStream getErrorStream() throws IOException;
+
+		abstract int getExitStatus();
+
+		abstract void close();
+	}
+
+	private class JschConnection extends Connection {
+		private ChannelExec channel;
+
+		private int exitStatus;
+
+		@Override
+		void exec(String commandName) throws TransportException {
+			initSession();
+			try {
+				channel = (ChannelExec) sock.openChannel("exec");
+				channel.setCommand(commandFor(commandName));
+			} catch (JSchException je) {
+				throw new TransportException(uri, je.getMessage(), je);
+			}
+		}
+
+		@Override
+		void connect() throws TransportException {
+			try {
+				channel.connect(getTimeout() > 0 ? getTimeout() * 1000 : 0);
+				if (!channel.isConnected())
+					throw new TransportException(uri, "connection failed");
+			} catch (JSchException e) {
+				throw new TransportException(uri, e.getMessage(), e);
+			}
+		}
+
+		@Override
+		InputStream getInputStream() throws IOException {
+			return channel.getInputStream();
+		}
+
+		@Override
+		OutputStream getOutputStream() throws IOException {
+			// JSch won't let us interrupt writes when we use our InterruptTimer
+			// to break out of a long-running write operation. To work around
+			// that we spawn a background thread to shuttle data through a pipe,
+			// as we can issue an interrupted write out of that. Its slower, so
+			// we only use this route if there is a timeout.
 			//
-	private OutputStream outputStream(ChannelExec channel) throws IOException {
 			final OutputStream out = channel.getOutputStream();
 			if (getTimeout() <= 0)
 				return out;
 			final PipedInputStream pipeIn = new PipedInputStream();
-		final StreamCopyThread copyThread = new StreamCopyThread(pipeIn, out);
+			final StreamCopyThread copier = new StreamCopyThread(pipeIn, out);
 			final PipedOutputStream pipeOut = new PipedOutputStream(pipeIn) {
 				@Override
 				public void flush() throws IOException {
 					super.flush();
-				copyThread.flush();
+					copier.flush();
 				}
 
 				@Override
 				public void close() throws IOException {
 					super.close();
 					try {
-					copyThread.join(getTimeout() * 1000);
+						copier.join(getTimeout() * 1000);
 					} catch (InterruptedException e) {
 						// Just wake early, the thread will terminate anyway.
 					}
 				}
 			};
-		copyThread.start();
+			copier.start();
 			return pipeOut;
 		}
 
+		@Override
+		InputStream getErrorStream() throws IOException {
+			return channel.getErrStream();
+		}
+
+		@Override
+		int getExitStatus() {
+			return exitStatus;
+		}
+
+		@Override
+		void close() {
+			if (channel != null) {
+				try {
+					exitStatus = channel.getExitStatus();
+					if (channel.isConnected())
+						channel.disconnect();
+				} finally {
+					channel = null;
+				}
+			}
+		}
+	}
+
 	class SshFetchConnection extends BasePackFetchConnection {
-		private ChannelExec channel;
+		private Connection conn;
 
 		private StreamCopyThread errorThread;
 
-		private int exitStatus;
+		SshFetchConnection(Connection conn) throws TransportException {
-
-		SshFetchConnection() throws TransportException {
 			super(TransportGitSsh.this);
+			this.conn = conn;
 			try {
 				final MessageWriter msg = new MessageWriter();
 				setMessageWriter(msg);
 
-				channel = exec(getOptionUploadPack());
+				conn.exec(getOptionUploadPack());
 
-				final InputStream upErr = channel.getErrStream();
+				final InputStream upErr = conn.getErrorStream();
 				errorThread = new StreamCopyThread(upErr, msg.getRawStream());
 				errorThread.start();
 
-				init(channel.getInputStream(), outputStream(channel));
+				init(conn.getInputStream(), conn.getOutputStream());
-				connect(channel);
+				conn.connect();
 
 			} catch (TransportException err) {
 				close();
@@ -266,7 +320,8 @@ class SshFetchConnection extends BasePackFetchConnection {
 				readAdvertisedRefs();
 			} catch (NoRemoteRepositoryException notFound) {
 				final String msgs = getMessages();
-				checkExecFailure(exitStatus, getOptionUploadPack(), msgs);
+				checkExecFailure(conn.getExitStatus(), getOptionUploadPack(),
+						msgs);
 				throw cleanNotFound(notFound, msgs);
 			}
 		}
@@ -286,40 +341,30 @@ public void close() {
 			}
 
 			super.close();
-
+			conn.close();
-			if (channel != null) {
-				try {
-					exitStatus = channel.getExitStatus();
-					if (channel.isConnected())
-						channel.disconnect();
-				} finally {
-					channel = null;
-				}
-			}
 		}
 	}
 
 	class SshPushConnection extends BasePackPushConnection {
-		private ChannelExec channel;
+		private Connection conn;
 
 		private StreamCopyThread errorThread;
 
-		private int exitStatus;
+		SshPushConnection(Connection conn) throws TransportException {
-
-		SshPushConnection() throws TransportException {
 			super(TransportGitSsh.this);
+			this.conn = conn;
 			try {
 				final MessageWriter msg = new MessageWriter();
 				setMessageWriter(msg);
 
-				channel = exec(getOptionReceivePack());
+				conn.exec(getOptionReceivePack());
 
-				final InputStream rpErr = channel.getErrStream();
+				final InputStream rpErr = conn.getErrorStream();
 				errorThread = new StreamCopyThread(rpErr, msg.getRawStream());
 				errorThread.start();
 
-				init(channel.getInputStream(), outputStream(channel));
+				init(conn.getInputStream(), conn.getOutputStream());
-				connect(channel);
+				conn.connect();
 
 			} catch (TransportException err) {
 				close();
@@ -334,7 +379,8 @@ class SshPushConnection extends BasePackPushConnection {
 				readAdvertisedRefs();
 			} catch (NoRemoteRepositoryException notFound) {
 				final String msgs = getMessages();
-				checkExecFailure(exitStatus, getOptionReceivePack(), msgs);
+				checkExecFailure(conn.getExitStatus(), getOptionReceivePack(),
+						msgs);
 				throw cleanNotFound(notFound, msgs);
 			}
 		}
@@ -354,16 +400,7 @@ public void close() {
 			}
 
 			super.close();
-
+			conn.close();
-			if (channel != null) {
-				try {
-					exitStatus = channel.getExitStatus();
-					if (channel.isConnected())
-						channel.disconnect();
-				} finally {
-					channel = null;
-				}
-			}
 		}
 	}
 }