1 files changed, 167 insertions, 0 deletions
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/SshSupport.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/SshSupport.java
new file mode 100644
index 0000000000..42a76b5b16
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/SshSupport.java
@@ -0,0 +1,167 @@
+/*
+ * Copyright (C) 2018, Markus Duft <markus.duft@ssi-schaefer.com> and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Distribution License v. 1.0 which is available at
+ * https://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+package org.eclipse.jgit.util;
+
+import java.io.IOException;
+import java.text.MessageFormat;
+import java.util.concurrent.TimeUnit;
+
+import org.eclipse.jgit.annotations.Nullable;
+import org.eclipse.jgit.errors.CommandFailedException;
+import org.eclipse.jgit.internal.JGitText;
+import org.eclipse.jgit.transport.CredentialsProvider;
+import org.eclipse.jgit.transport.RemoteSession;
+import org.eclipse.jgit.transport.SshSessionFactory;
+import org.eclipse.jgit.transport.URIish;
+import org.eclipse.jgit.util.io.MessageWriter;
+import org.eclipse.jgit.util.io.StreamCopyThread;
+
+/**
+ * Extra utilities to support usage of SSH.
+ *
+ * @since 5.0
+ */
+public class SshSupport {
+
+	/**
+	 * Utility to execute a remote SSH command and read the first line of
+	 * output.
+	 *
+	 * @param sshUri
+	 *            the SSH remote URI
+	 * @param provider
+	 *            the {@link CredentialsProvider} or <code>null</code>.
+	 * @param fs
+	 *            the {@link FS} implementation passed to
+	 *            {@link SshSessionFactory}
+	 * @param command
+	 *            the remote command to execute.
+	 * @param timeout
+	 *            a timeout in seconds. The timeout may be exceeded in corner
+	 *            cases.
+	 * @return The entire output read from stdout.
+	 * @throws IOException
+	 *             if an IO error occurred
+	 * @throws CommandFailedException
+	 *             if the ssh command execution failed, error message contains
+	 *             the content of stderr.
+	 */
+	public static String runSshCommand(URIish sshUri,
+			@Nullable CredentialsProvider provider, FS fs, String command,
+			int timeout) throws IOException, CommandFailedException {
+		RemoteSession session = null;
+		Process process = null;
+		StreamCopyThread errorThread = null;
+		StreamCopyThread outThread = null;
+		CommandFailedException failure = null;
+		@SuppressWarnings("resource")
+		MessageWriter stderr = new MessageWriter();
+		@SuppressWarnings("resource")
+		MessageWriter stdout = new MessageWriter();
+		String out;
+		try {
+			long start = System.nanoTime();
+			session = SshSessionFactory.getInstance().getSession(sshUri,
+					provider, fs, 1000 * timeout);
+			int commandTimeout = timeout;
+			if (timeout > 0) {
+				commandTimeout = checkTimeout(command, timeout, start);
+			}
+			process = session.exec(command, commandTimeout);
+			if (timeout > 0) {
+				commandTimeout = checkTimeout(command, timeout, start);
+			}
+			errorThread = new StreamCopyThread(process.getErrorStream(),
+					stderr.getRawStream());
+			errorThread.start();
+			outThread = new StreamCopyThread(process.getInputStream(),
+					stdout.getRawStream());
+			outThread.start();
+			try {
+				boolean finished = false;
+				if (timeout <= 0) {
+					process.waitFor();
+					finished = true;
+				} else {
+					finished = process.waitFor(commandTimeout,
+							TimeUnit.SECONDS);
+				}
+				if (finished) {
+					out = stdout.toString();
+				} else {
+					out = null; // still running after timeout
+				}
+			} catch (InterruptedException e) {
+				out = null; // error
+			}
+		} finally {
+			if (errorThread != null) {
+				try {
+					errorThread.halt();
+				} catch (InterruptedException e) {
+					// Stop waiting and return anyway.
+				} finally {
+					errorThread = null;
+				}
+			}
+			if (outThread != null) {
+				try {
+					outThread.halt();
+				} catch (InterruptedException e) {
+					// Stop waiting and return anyway.
+				} finally {
+					outThread = null;
+				}
+			}
+			if (process != null) {
+				try {
+					if (process.exitValue() != 0) {
+						failure = new CommandFailedException(
+								process.exitValue(),
+								MessageFormat.format(
+										JGitText.get().sshCommandFailed,
+										command, stderr.toString()));
+					}
+					// It was successful after all
+					out = stdout.toString();
+				} catch (IllegalThreadStateException e) {
+					failure = new CommandFailedException(0,
+							MessageFormat.format(
+									JGitText.get().sshCommandTimeout, command,
+									Integer.valueOf(timeout)));
+				}
+				process.destroy();
+			}
+			stderr.close();
+			stdout.close();
+			if (session != null) {
+				SshSessionFactory.getInstance().releaseSession(session);
+			}
+		}
+		if (failure != null) {
+			throw failure;
+		}
+		return out;
+	}
+
+	private static int checkTimeout(String command, int timeout, long since)
+			throws CommandFailedException {
+		long elapsed = System.nanoTime() - since;
+		int newTimeout = timeout
+				- (int) TimeUnit.NANOSECONDS.toSeconds(elapsed);
+		if (newTimeout <= 0) {
+			// All time used up for connecting the session
+			throw new CommandFailedException(0,
+					MessageFormat.format(JGitText.get().sshCommandTimeout,
+							command, Integer.valueOf(timeout)));
+		}
+		return newTimeout;
+	}
+}