machine.java

nachos操作系统框架

// PART OF THE MACHINE SIMULATION. DO NOT CHANGE.

package nachos.machine;

import nachos.security.*;
import nachos.ag.*;

import java.io.File;

/**
 * The master class of the simulated machine. Processes command line arguments,
 * constructs all simulated hardware devices, and starts the grader.
 */
public final class Machine {
    /**
     * Nachos main entry point.
     *
     * @param	args	the command line arguments.
     */
    public static void main(final String[] args) {
	System.out.print("nachos 5.0j initializing...");
	
	Lib.assert(Machine.args == null);
	Machine.args = args;

	processArgs();

	Config.load(configFileName);

	// get the current directory (.)
	baseDirectory = new File(new File("").getAbsolutePath());
	// get the nachos directory (./nachos)
	nachosDirectory = new File(baseDirectory, "nachos");

	String testDirectoryName =
	    Config.getString("FileSystem.testDirectory");

	// get the test directory
	if (testDirectoryName != null) {
	    testDirectory = new File(testDirectoryName);
	}
	else {
	    // use ../test
	    testDirectory = new File(baseDirectory.getParentFile(), "test");
	}

	securityManager = new NachosSecurityManager(testDirectory);
	privilege = securityManager.getPrivilege();

	privilege.machine = new MachinePrivilege();

	TCB.givePrivilege(privilege);
	privilege.stats = stats;

	securityManager.enable();
	createDevices();
	checkUserClasses();

	autoGrader = (AutoGrader) Lib.constructObject(autoGraderClassName);

	new TCB().start(new Runnable() {
	    public void run() { autoGrader.start(privilege); }
	});
    }

    /**
     * Yield to non-Nachos threads. Use in non-preemptive JVM's to give
     * non-Nachos threads a chance to run.
     */
    public static void yield() {
	Thread.yield();
    }

    /**
     * Terminate Nachos. Same as <tt>TCB.die()</tt>.
     */
    public static void terminate() {
	TCB.die();
    }

    /**
     * Terminate Nachos as the result of an unhandled exception or error.
     *
     * @param	e	the exception or error.
     */
    public static void terminate(Throwable e) {
	if (e instanceof ThreadDeath)
	    throw (ThreadDeath) e;
	
	e.printStackTrace();
	terminate();
    }

    /**
     * Print stats, and terminate Nachos.
     */
    public static void halt() {
	System.out.print("Machine halting!\n\n");
	stats.print();
	terminate();
    }

    /**
     * Return an array containing all command line arguments.
     *
     * @return	the command line arguments passed to Nachos.
     */
    public static String[] getCommandLineArguments() {
	String[] result = new String[args.length];

	System.arraycopy(args, 0, result, 0, args.length);

	return result;
    }

    private static void processArgs() {
	for (int i=0; i<args.length; ) {
	    String arg = args[i++];
	    if (arg.length() > 0 && arg.charAt(0) == '-') {
		if (arg.equals("-d")) {
		    Lib.assert(i < args.length, "switch without argument");
		    Lib.enableDebugFlags(args[i++]);
		}
		else if (arg.equals("-h")) {
		    System.out.print(help);
		    System.exit(1);
		}
		else if (arg.equals("-m")) {
		    Lib.assert(i < args.length, "switch without argument");
		    try {
			numPhysPages = Integer.parseInt(args[i++]);
		    }
		    catch (NumberFormatException e) {
			Lib.assertNotReached("bad value for -m switch");
		    }
		}
		else if (arg.equals("-s")) {
		    Lib.assert(i < args.length, "switch without argument");
		    try {
			randomSeed = Long.parseLong(args[i++]);
		    }
		    catch (NumberFormatException e) {
			Lib.assertNotReached("bad value for -s switch");
		    }
		}
		else if (arg.equals("-x")) {
		    Lib.assert(i < args.length, "switch without argument");
		    shellProgramName = args[i++];		    
		}		    
		else if (arg.equals("-z")) {
		    System.out.print(copyright);
		    System.exit(1);
		}
		// these switches are reserved for the autograder
		else if (arg.equals("-[]")) {
		    Lib.assert(i < args.length, "switch without argument");
		    configFileName = args[i++];
		}
		else if (arg.equals("--")) {
		    Lib.assert(i < args.length, "switch without argument");
		    autoGraderClassName = args[i++];
		}
	    }
	}

	Lib.seedRandom(randomSeed);
    }

    private static void createDevices() {
	interrupt = new Interrupt(privilege);
	timer = new Timer(privilege);

	if (Config.getBoolean("Machine.bank"))
	    bank = new ElevatorBank(privilege);

	if (Config.getBoolean("Machine.processor")) {
	    if (numPhysPages == -1)
		numPhysPages = Config.getInteger("Processor.numPhysPages");
	    processor = new Processor(privilege, numPhysPages);
	}				      

	if (Config.getBoolean("Machine.console"))
	    console = new StandardConsole(privilege);

	if (Config.getBoolean("Machine.stubFileSystem"))
	    stubFileSystem = new StubFileSystem(privilege, testDirectory);

	if (Config.getBoolean("Machine.networkLink"))
	    networkLink = new NetworkLink(privilege);
    }

    private static void checkUserClasses() {
	System.out.print(" user-check");
	
	Class aclsInt = (new int[0]).getClass();
	Class clsObject = Lib.loadClass("java.lang.Object");
	Class clsRunnable = Lib.loadClass("java.lang.Runnable");
	Class clsString = Lib.loadClass("java.lang.String");

	Class clsKernel = Lib.loadClass("nachos.machine.Kernel");
	Class clsFileSystem = Lib.loadClass("nachos.machine.FileSystem");
	Class clsRiderControls = Lib.loadClass("nachos.machine.RiderControls");
	Class clsElevatorControls =
	    Lib.loadClass("nachos.machine.ElevatorControls");
	Class clsRiderInterface =
	    Lib.loadClass("nachos.machine.RiderInterface");
	Class clsElevatorControllerInterface =
	    Lib.loadClass("nachos.machine.ElevatorControllerInterface");

	Class clsAlarm = Lib.loadClass("nachos.threads.Alarm");
	Class clsThreadedKernel =
	    Lib.loadClass("nachos.threads.ThreadedKernel");
	Class clsKThread = Lib.loadClass("nachos.threads.KThread");
	Class clsCommunicator = Lib.loadClass("nachos.threads.Communicator");
	Class clsSemaphore = Lib.loadClass("nachos.threads.Semaphore");
	Class clsLock = Lib.loadClass("nachos.threads.Lock");
	Class clsCondition = Lib.loadClass("nachos.threads.Condition");
	Class clsCondition2 = Lib.loadClass("nachos.threads.Condition2");
	Class clsRider = Lib.loadClass("nachos.threads.Rider");
	Class clsElevatorController =
	    Lib.loadClass("nachos.threads.ElevatorController");

	Lib.checkDerivation(clsThreadedKernel, clsKernel);
	
	Lib.checkStaticField(clsThreadedKernel, "alarm", clsAlarm);
	Lib.checkStaticField(clsThreadedKernel, "fileSystem", clsFileSystem);
	
	Lib.checkMethod(clsAlarm, "waitUntil", new Class[] { long.class },
			void.class);
	
	Lib.checkConstructor(clsKThread, new Class[] { });
	Lib.checkConstructor(clsKThread, new Class[] { clsRunnable });

	Lib.checkStaticMethod(clsKThread, "currentThread", new Class[] {},
			      clsKThread);
	Lib.checkStaticMethod(clsKThread, "finish", new Class[] {},
			      void.class);
	Lib.checkStaticMethod(clsKThread, "yield", new Class[] {}, void.class);
	Lib.checkStaticMethod(clsKThread, "sleep", new Class[] {}, void.class);

	Lib.checkMethod(clsKThread, "setTarget", new Class[]{ clsRunnable },
			clsKThread);
	Lib.checkMethod(clsKThread, "setName", new Class[] { clsString },
			clsKThread);
	Lib.checkMethod(clsKThread, "getName", new Class[] { }, clsString);