package jenkins.slaves;
import hudson.Extension;
import hudson.FilePath;
import hudson.model.Computer;
import hudson.model.TaskListener;
import hudson.remoting.Callable;
import hudson.remoting.Channel;
import hudson.remoting.StandardOutputStream;
import hudson.slaves.ComputerListener;
import hudson.util.jna.GNUCLibrary;
import java.io.File;
import java.io.FileDescriptor;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.lang.reflect.Constructor;
import java.util.logging.Logger;
/**
* @author Kohsuke Kawaguchi
*/
@Extension
public class StandardOutputSwapper extends ComputerListener {
@Override
public void preOnline(Computer c, Channel channel, FilePath root, TaskListener listener) {
if (disabled) return;
try {
if (channel.call(new ChannelSwapper()))
listener.getLogger().println("Evacuated stdout");
} catch (Throwable e) {
LOGGER.fine("Fatal problem swapping file descriptors " + c.getName());
}
}
private static final class ChannelSwapper implements Callable<Boolean,Exception> {
public Boolean call() throws Exception {
if (File.pathSeparatorChar==';') return false; // Windows
OutputStream o = Channel.current().getUnderlyingOutput();
if (o instanceof StandardOutputStream) {
StandardOutputStream stdout = (StandardOutputStream)o;
// duplicate the OS file descriptor and create FileOutputStream around it
int out = GNUCLibrary.LIBC.dup(1);
if (out<0) throw new IOException("Failed to dup(1)");
Constructor<FileDescriptor> c = FileDescriptor.class.getDeclaredConstructor(int.class);
c.setAccessible(true);
FileOutputStream fos = new FileOutputStream(c.newInstance(out));
// swap it into channel so that it'll use the new file descriptor
stdout.swap(fos);
// close fd=1 (stdout) and duplicate fd=2 (stderr) into fd=1 (stdout)
GNUCLibrary.LIBC.close(1);
GNUCLibrary.LIBC.dup2(2,1);
return true;
}
return false;
}
}
private static final Logger LOGGER = Logger.getLogger(StandardOutputSwapper.class.getName());
public static boolean disabled = Boolean.getBoolean(StandardOutputSwapper.class.getName()+".disabled");
}