src/main/java/org/luaj/vm3/lib/OsLib.java - minecraft/opencomputers - Rivoreo Source Code Repositories

 /*******************************************************************************
 * Copyright (c) 2009 Luaj.org. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 ******************************************************************************/
 package org.luaj.vm3.lib;

 import java.io.IOException;
 import java.util.Calendar;
 import java.util.Date;

 import org.luaj.vm3.Buffer;
 import org.luaj.vm3.Globals;
 import org.luaj.vm3.LuaTable;
 import org.luaj.vm3.LuaValue;
 import org.luaj.vm3.Varargs;

 /**
  * Subclass of {@link LibFunction} which implements the standard lua {@code os} library.
  * <p>
  * It is a usable base with simplified stub functions
  * for library functions that cannot be implemented uniformly
  * on Jse and Jme.
  * <p>
  * This can be installed as-is on either platform, or extended
  * and refined to be used in a complete Jse implementation.
  * <p>
  * Because the nature of the {@code os} library is to encapsulate
  * os-specific features, the behavior of these functions varies considerably
  * from their counterparts in the C platform.
  * <p>
  * The following functions have limited implementations of features
  * that are not supported well on Jme:
  * <ul>
  * <li>{@code execute()}</li>
  * <li>{@code remove()}</li>
  * <li>{@code rename()}</li>
  * <li>{@code tmpname()}</li>
  * </ul>
  * <p>
  * Typically, this library is included as part of a call to either
  * {@link JsePlatform#standardGlobals()} or {@link JmePlatform#standardGlobals()}
  * <pre> {@code
  * Globals globals = JsePlatform.standardGlobals();
  * System.out.println( globals.get("os").get("time").call() );
  * } </pre>
  * In this example the platform-specific {@link JseOsLib} library will be loaded, which will include
  * the base functionality provided by this class.
  * <p>
  * To instantiate and use it directly,
  * link it into your globals table via {@link LuaValue#load(LuaValue)} using code such as:
  * <pre> {@code
  * Globals globals = new Globals();
  * globals.load(new JseBaseLib());
  * globals.load(new PackageLib());
  * globals.load(new OsLib());
  * System.out.println( globals.get("os").get("time").call() );
  * } </pre>
  * <p>
   * @see LibFunction
  * @see JseOsLib
  * @see JsePlatform
  * @see JmePlatform
  * @see <a href="http://www.lua.org/manual/5.1/manual.html#5.8">http://www.lua.org/manual/5.1/manual.html#5.8</a>
  */
 public class OsLib extends TwoArgFunction {
 	public static String TMP_PREFIX = ".luaj";
 	public static String TMP_SUFFIX = "tmp";

 	private static final int CLOCK = 0;
 	private static final int DATE = 1;
 	private static final int DIFFTIME = 2;
 	private static final int EXECUTE = 3;
 	private static final int EXIT = 4;
 	private static final int GETENV = 5;
 	private static final int REMOVE = 6;
 	private static final int RENAME = 7;
 	private static final int SETLOCALE = 8;
 	private static final int TIME = 9;
 	private static final int TMPNAME = 10;

 	private static final String[] NAMES = { "clock", "date", "difftime", "execute", "exit", "getenv", "remove", "rename", "setlocale", "time", "tmpname", };

 	private static final long t0 = System.currentTimeMillis();
 	private static long tmpnames = t0;

 	protected Globals globals;

 	/**
 	 * Create and OsLib instance.
 	 */
 	public OsLib() {}

 	public LuaValue call(LuaValue modname, LuaValue env) {
 		globals = env.checkglobals();
 		LuaTable os = new LuaTable();
 		for (int i = 0; i < NAMES.length; ++i)
 			os.set(NAMES[i], new OsLibFunc(i, NAMES[i]));
 		env.set("os", os);
 		env.get("package").get("loaded").set("os", os);
 		return os;
 	}

 	class OsLibFunc extends VarArgFunction {
 		public OsLibFunc(int opcode, String name) {
 			this.opcode = opcode;
 			this.name = name;
 		}

 		public Varargs invoke(Varargs args) {
 			try {
 				switch (opcode) {
 				case CLOCK:
 					return valueOf(clock());
 				case DATE: {
 					String s = args.optjstring(1, "%c");
 					double t = args.isnumber(2) ? args.todouble(2) : time(null);
 					if (s.equals("*t")) {
 						Calendar d = Calendar.getInstance();
 						d.setTime(new Date((long) (t * 1000)));
 						LuaTable tbl = LuaValue.tableOf();
 						tbl.set("year", LuaValue.valueOf(d.get(Calendar.YEAR)));
 						tbl.set("month", LuaValue.valueOf(d.get(Calendar.MONTH) + 1));
 						tbl.set("day", LuaValue.valueOf(d.get(Calendar.DAY_OF_MONTH)));
 						tbl.set("hour", LuaValue.valueOf(d.get(Calendar.HOUR)));
 						tbl.set("min", LuaValue.valueOf(d.get(Calendar.MINUTE)));
 						tbl.set("sec", LuaValue.valueOf(d.get(Calendar.SECOND)));
 						tbl.set("wday", LuaValue.valueOf(d.get(Calendar.DAY_OF_WEEK)));
 						tbl.set("yday", LuaValue.valueOf(d.get(0x6))); // Day of year
 						tbl.set("isdst", LuaValue.valueOf(isDaylightSavingsTime(d)));
 						return tbl;
 					}
 					return valueOf(date(s, t == -1 ? time(null) : t));
 				}
 				case DIFFTIME:
 					return valueOf(difftime(args.checkdouble(1), args.checkdouble(2)));
 				case EXECUTE:
 					return execute(args.optjstring(1, null));
 				case EXIT:
 					exit(args.optint(1, 0));
 					return NONE;
 				case GETENV: {
 					final String val = getenv(args.checkjstring(1));
 					return val != null ? valueOf(val) : NIL;
 				}
 				case REMOVE:
 					remove(args.checkjstring(1));
 					return LuaValue.TRUE;
 				case RENAME:
 					rename(args.checkjstring(1), args.checkjstring(2));
 					return LuaValue.TRUE;
 				case SETLOCALE: {
 					String s = setlocale(args.optjstring(1, null), args.optjstring(2, "all"));
 					return s != null ? valueOf(s) : NIL;
 				}
 				case TIME:
 					return valueOf(time(args.opttable(1, null)));
 				case TMPNAME:
 					return valueOf(tmpname());
 				}
 				return NONE;
 			} catch (IOException e) {
 				return varargsOf(NIL, valueOf(e.getMessage()));
 			}
 		}
 	}

 	/**
 	 * @return an approximation of the amount in seconds of CPU time used by
 	 * the program.  For luaj this simple returns the elapsed time since the
 	 * OsLib class was loaded.
 	 */
 	protected double clock() {
 		return (System.currentTimeMillis() - t0) / 1000.;
 	}

 	/**
 	 * Returns the number of seconds from time t1 to time t2.
 	 * In POSIX, Windows, and some other systems, this value is exactly t2-t1.
 	 * @param t2
 	 * @param t1
 	 * @return diffeence in time values, in seconds
 	 */
 	protected double difftime(double t2, double t1) {
 		return t2 - t1;
 	}

 	/**
 	 * If the time argument is present, this is the time to be formatted
 	 * (see the os.time function for a description of this value).
 	 * Otherwise, date formats the current time.
 	 *
 	 * Date returns the date as a string,
 	 * formatted according to the same rules as ANSII strftime, but without
 	 * support for %g, %G, or %V.
 	 *
 	 * When called without arguments, date returns a reasonable date and
 	 * time representation that depends on the host system and on the
 	 * current locale (that is, os.date() is equivalent to os.date("%c")).
 	 *
 	 * @param format
 	 * @param time time since epoch, or -1 if not supplied
 	 * @return a LString or a LTable containing date and time,
 	 * formatted according to the given string format.
 	 */
 	public String date(String format, double time) {
 		Calendar d = Calendar.getInstance();
 		d.setTime(new Date((long) (time * 1000)));
 		if (format.startsWith("!")) {
 			time -= timeZoneOffset(d);
 			d.setTime(new Date((long) (time * 1000)));
 			format = format.substring(1);
 		}
 		byte[] fmt = format.getBytes();
 		final int n = fmt.length;
 		Buffer result = new Buffer(n);
 		byte c;
 		for (int i = 0; i < n;) {
 			switch (c = fmt[i++]) {
 			case '\n':
 				result.append("\n");
 				break;
 			default:
 				result.append(c);
 				break;
 			case '%':
 				if (i >= n)
 					break;
 				switch (c = fmt[i++]) {
 				default:
 					LuaValue.argerror(1, "invalid conversion specifier '%" + (char)c + "'");
 					break;
 				case '%':
 					result.append((byte) '%');
 					break;
 				case 'a':
 					result.append(WeekdayNameAbbrev[d.get(Calendar.DAY_OF_WEEK) - 1]);
 					break;
 				case 'A':
 					result.append(WeekdayName[d.get(Calendar.DAY_OF_WEEK) - 1]);
 					break;
 				case 'b':
 					result.append(MonthNameAbbrev[d.get(Calendar.MONTH)]);
 					break;
 				case 'B':
 					result.append(MonthName[d.get(Calendar.MONTH)]);
 					break;
 				case 'c':
 					result.append(date("%a %b %d %H:%M:%S %Y", time));
 					break;
 				case 'd':
 					result.append(String.valueOf(100 + d.get(Calendar.DAY_OF_MONTH)).substring(1));
 					break;
 				case 'H':
 					result.append(String.valueOf(100 + d.get(Calendar.HOUR_OF_DAY)).substring(1));
 					break;
 				case 'I':
 					result.append(String.valueOf(100 + (d.get(Calendar.HOUR_OF_DAY) % 12)).substring(1));
 					break;
 				case 'j': { // day of year.
 					Calendar y0 = beginningOfYear(d);
 					int dayOfYear = (int) ((d.getTime().getTime() - y0.getTime().getTime()) / (24 * 3600L * 1000L));
 					result.append(String.valueOf(1001 + dayOfYear).substring(1));
 					break;
 				}
 				case 'm':
 					result.append(String.valueOf(101 + d.get(Calendar.MONTH)).substring(1));
 					break;
 				case 'M':
 					result.append(String.valueOf(100 + d.get(Calendar.MINUTE)).substring(1));
 					break;
 				case 'p':
 					result.append(d.get(Calendar.HOUR_OF_DAY) < 12 ? "AM" : "PM");
 					break;
 				case 'S':
 					result.append(String.valueOf(100 + d.get(Calendar.SECOND)).substring(1));
 					break;
 				case 'U':
 					result.append(String.valueOf(weekNumber(d, 0)));
 					break;
 				case 'w':
 					result.append(String.valueOf((d.get(Calendar.DAY_OF_WEEK) + 6) % 7));
 					break;
 				case 'W':
 					result.append(String.valueOf(weekNumber(d, 1)));
 					break;
 				case 'x':
 					result.append(date("%m/%d/%y", time));
 					break;
 				case 'X':
 					result.append(date("%H:%M:%S", time));
 					break;
 				case 'y':
 					result.append(String.valueOf(d.get(Calendar.YEAR)).substring(2));
 					break;
 				case 'Y':
 					result.append(String.valueOf(d.get(Calendar.YEAR)));
 					break;
 				case 'z': {
 					final int tzo = timeZoneOffset(d) / 60;
 					final int a = Math.abs(tzo);
 					final String h = String.valueOf(100 + a / 60).substring(1);
 					final String m = String.valueOf(100 + a % 60).substring(1);
 					result.append((tzo >= 0 ? "+" : "-") + h + m);
 					break;
 				}
 				}
 			}
 		}
 		return result.tojstring();
 	}

 	private static final String[] WeekdayNameAbbrev = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
 	private static final String[] WeekdayName = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };
 	private static final String[] MonthNameAbbrev = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
 	private static final String[] MonthName = { "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" };

 	private Calendar beginningOfYear(Calendar d) {
 		Calendar y0 = Calendar.getInstance();
 		y0.setTime(d.getTime());
 		y0.set(Calendar.MONTH, 0);
 		y0.set(Calendar.DAY_OF_MONTH, 1);
 		y0.set(Calendar.HOUR_OF_DAY, 0);
 		y0.set(Calendar.MINUTE, 0);
 		y0.set(Calendar.SECOND, 0);
 		y0.set(Calendar.MILLISECOND, 0);
 		return y0;
 	}

 	private int weekNumber(Calendar d, int startDay) {
 		Calendar y0 = beginningOfYear(d);
 		y0.set(Calendar.DAY_OF_MONTH, 1 + (startDay + 8 - y0.get(Calendar.DAY_OF_WEEK)) % 7);
 		if (y0.after(d)) {
 			y0.set(Calendar.YEAR, y0.get(Calendar.YEAR) - 1);
 			y0.set(Calendar.DAY_OF_MONTH, 1 + (startDay + 8 - y0.get(Calendar.DAY_OF_WEEK)) % 7);
 		}
 		long dt = d.getTime().getTime() - y0.getTime().getTime();
 		return 1 + (int) (dt / (7L * 24L * 3600L * 1000L));
 	}

 	private int timeZoneOffset(Calendar d) {
 		int localStandarTimeMillis = (d.get(Calendar.HOUR_OF_DAY) * 3600 + d.get(Calendar.MINUTE) * 60 + d.get(Calendar.SECOND)) * 1000;
 		return d.getTimeZone().getOffset(1, d.get(Calendar.YEAR), d.get(Calendar.MONTH), d.get(Calendar.DAY_OF_MONTH), d.get(Calendar.DAY_OF_WEEK), localStandarTimeMillis) / 1000;
 	}

 	private boolean isDaylightSavingsTime(Calendar d) {
 		return timeZoneOffset(d) != d.getTimeZone().getRawOffset() / 1000;
 	}

 	/**
 	 * This function is equivalent to the C function system.
 	 * It passes command to be executed by an operating system shell.
 	 * It returns a status code, which is system-dependent.
 	 * If command is absent, then it returns nonzero if a shell
 	 * is available and zero otherwise.
 	 * @param command command to pass to the system
 	 */
 	protected Varargs execute(String command) {
 		return varargsOf(NIL, valueOf("exit"), ONE);
 	}

 	/**
 	 * Calls the C function exit, with an optional code, to terminate the host program.
 	 * @param code
 	 */
 	protected void exit(int code) {
 		System.exit(code);
 	}

 	/**
 	 * Returns the value of the process environment variable varname,
 	 * or null if the variable is not defined.
 	 * @param varname
 	 * @return String value, or null if not defined
 	 */
 	protected String getenv(String varname) {
 		return System.getProperty(varname);
 	}

 	/**
 	 * Deletes the file or directory with the given name.
 	 * Directories must be empty to be removed.
 	 * If this function fails, it throws and IOException
 	 *
 	 * @param filename
 	 * @throws IOException if it fails
 	 */
 	protected void remove(String filename) throws IOException {
 		throw new IOException("not implemented");
 	}

 	/**
 	 * Renames file or directory named oldname to newname.
 	 * If this function fails,it throws and IOException
 	 *
 	 * @param oldname old file name
 	 * @param newname new file name
 	 * @throws IOException if it fails
 	 */
 	protected void rename(String oldname, String newname) throws IOException {
 		throw new IOException("not implemented");
 	}

 	/**
 	 * Sets the current locale of the program. locale is a string specifying
 	 * a locale; category is an optional string describing which category to change:
 	 * "all", "collate", "ctype", "monetary", "numeric", or "time"; the default category
 	 * is "all".
 	 *
 	 * If locale is the empty string, the current locale is set to an implementation-
 	 * defined native locale. If locale is the string "C", the current locale is set
 	 * to the standard C locale.
 	 *
 	 * When called with null as the first argument, this function only returns the
 	 * name of the current locale for the given category.
 	 *
 	 * @param locale
 	 * @param category
 	 * @return the name of the new locale, or null if the request
 	 * cannot be honored.
 	 */
 	protected String setlocale(String locale, String category) {
 		return "C";
 	}

 	/**
 	 * Returns the current time when called without arguments,
 	 * or a time representing the date and time specified by the given table.
 	 * This table must have fields year, month, and day,
 	 * and may have fields hour, min, sec, and isdst
 	 * (for a description of these fields, see the os.date function).
 	 * @param table
 	 * @return long value for the time
 	 */
 	protected double time(LuaTable table) {
 		java.util.Date d;
 		if (table == null) {
 			d = new java.util.Date();
 		} else {
 			Calendar c = Calendar.getInstance();
 			c.set(Calendar.YEAR, table.get("year").checkint());
 			c.set(Calendar.MONTH, table.get("month").checkint() - 1);
 			c.set(Calendar.DAY_OF_MONTH, table.get("day").checkint());
 			c.set(Calendar.HOUR, table.get("hour").optint(12));
 			c.set(Calendar.MINUTE, table.get("min").optint(0));
 			c.set(Calendar.SECOND, table.get("sec").optint(0));
 			c.set(Calendar.MILLISECOND, 0);
 			d = c.getTime();
 		}
 		return d.getTime() / 1000.;
 	}

 	/**
 	 * Returns a string with a file name that can be used for a temporary file.
 	 * The file must be explicitly opened before its use and explicitly removed
 	 * when no longer needed.
 	 *
 	 * On some systems (POSIX), this function also creates a file with that name,
 	 * to avoid security risks. (Someone else might create the file with wrong
 	 * permissions in the time between getting the name and creating the file.)
 	 * You still have to open the file to use it and to remove it (even if you
 	 * do not use it).
 	 *
 	 * @return String filename to use
 	 */
 	protected String tmpname() {
 		synchronized (OsLib.class) {
 			return TMP_PREFIX + (tmpnames++) + TMP_SUFFIX;
 		}
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2009 Luaj.org. All rights reserved.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	******************************************************************************/
	package org.luaj.vm3.lib;

	import java.io.IOException;
	import java.util.Calendar;
	import java.util.Date;

	import org.luaj.vm3.Buffer;
	import org.luaj.vm3.Globals;
	import org.luaj.vm3.LuaTable;
	import org.luaj.vm3.LuaValue;
	import org.luaj.vm3.Varargs;

	/**
	* Subclass of {@link LibFunction} which implements the standard lua {@code os} library.
	* <p>
	* It is a usable base with simplified stub functions
	* for library functions that cannot be implemented uniformly
	* on Jse and Jme.
	* <p>
	* This can be installed as-is on either platform, or extended
	* and refined to be used in a complete Jse implementation.
	* <p>
	* Because the nature of the {@code os} library is to encapsulate
	* os-specific features, the behavior of these functions varies considerably
	* from their counterparts in the C platform.
	* <p>
	* The following functions have limited implementations of features
	* that are not supported well on Jme:
	* <ul>
	* <li>{@code execute()}</li>
	* <li>{@code remove()}</li>
	* <li>{@code rename()}</li>
	* <li>{@code tmpname()}</li>
	* </ul>
	* <p>
	* Typically, this library is included as part of a call to either
	* {@link JsePlatform#standardGlobals()} or {@link JmePlatform#standardGlobals()}
	* <pre> {@code
	* Globals globals = JsePlatform.standardGlobals();
	* System.out.println( globals.get("os").get("time").call() );
	* } </pre>
	* In this example the platform-specific {@link JseOsLib} library will be loaded, which will include
	* the base functionality provided by this class.
	* <p>
	* To instantiate and use it directly,
	* link it into your globals table via {@link LuaValue#load(LuaValue)} using code such as:
	* <pre> {@code
	* Globals globals = new Globals();
	* globals.load(new JseBaseLib());
	* globals.load(new PackageLib());
	* globals.load(new OsLib());
	* System.out.println( globals.get("os").get("time").call() );
	* } </pre>
	* <p>
	* @see LibFunction
	* @see JseOsLib
	* @see JsePlatform
	* @see JmePlatform
	* @see <a href="http://www.lua.org/manual/5.1/manual.html#5.8">http://www.lua.org/manual/5.1/manual.html#5.8</a>
	*/
	public class OsLib extends TwoArgFunction {
	public static String TMP_PREFIX = ".luaj";
	public static String TMP_SUFFIX = "tmp";

	private static final int CLOCK = 0;
	private static final int DATE = 1;
	private static final int DIFFTIME = 2;
	private static final int EXECUTE = 3;
	private static final int EXIT = 4;
	private static final int GETENV = 5;
	private static final int REMOVE = 6;
	private static final int RENAME = 7;
	private static final int SETLOCALE = 8;
	private static final int TIME = 9;
	private static final int TMPNAME = 10;

	private static final String[] NAMES = { "clock", "date", "difftime", "execute", "exit", "getenv", "remove", "rename", "setlocale", "time", "tmpname", };

	private static final long t0 = System.currentTimeMillis();
	private static long tmpnames = t0;

	protected Globals globals;

	/**
	* Create and OsLib instance.
	*/
	public OsLib() {}

	public LuaValue call(LuaValue modname, LuaValue env) {
	globals = env.checkglobals();
	LuaTable os = new LuaTable();
	for (int i = 0; i < NAMES.length; ++i)
	os.set(NAMES[i], new OsLibFunc(i, NAMES[i]));
	env.set("os", os);
	env.get("package").get("loaded").set("os", os);
	return os;
	}

	class OsLibFunc extends VarArgFunction {
	public OsLibFunc(int opcode, String name) {
	this.opcode = opcode;
	this.name = name;
	}

	public Varargs invoke(Varargs args) {
	try {
	switch (opcode) {
	case CLOCK:
	return valueOf(clock());
	case DATE: {
	String s = args.optjstring(1, "%c");
	double t = args.isnumber(2) ? args.todouble(2) : time(null);
	if (s.equals("*t")) {
	Calendar d = Calendar.getInstance();
	d.setTime(new Date((long) (t * 1000)));
	LuaTable tbl = LuaValue.tableOf();
	tbl.set("year", LuaValue.valueOf(d.get(Calendar.YEAR)));
	tbl.set("month", LuaValue.valueOf(d.get(Calendar.MONTH) + 1));
	tbl.set("day", LuaValue.valueOf(d.get(Calendar.DAY_OF_MONTH)));
	tbl.set("hour", LuaValue.valueOf(d.get(Calendar.HOUR)));
	tbl.set("min", LuaValue.valueOf(d.get(Calendar.MINUTE)));
	tbl.set("sec", LuaValue.valueOf(d.get(Calendar.SECOND)));
	tbl.set("wday", LuaValue.valueOf(d.get(Calendar.DAY_OF_WEEK)));
	tbl.set("yday", LuaValue.valueOf(d.get(0x6))); // Day of year
	tbl.set("isdst", LuaValue.valueOf(isDaylightSavingsTime(d)));
	return tbl;
	}
	return valueOf(date(s, t == -1 ? time(null) : t));
	}
	case DIFFTIME:
	return valueOf(difftime(args.checkdouble(1), args.checkdouble(2)));
	case EXECUTE:
	return execute(args.optjstring(1, null));
	case EXIT:
	exit(args.optint(1, 0));
	return NONE;
	case GETENV: {
	final String val = getenv(args.checkjstring(1));
	return val != null ? valueOf(val) : NIL;
	}
	case REMOVE:
	remove(args.checkjstring(1));
	return LuaValue.TRUE;
	case RENAME:
	rename(args.checkjstring(1), args.checkjstring(2));
	return LuaValue.TRUE;
	case SETLOCALE: {
	String s = setlocale(args.optjstring(1, null), args.optjstring(2, "all"));
	return s != null ? valueOf(s) : NIL;
	}
	case TIME:
	return valueOf(time(args.opttable(1, null)));
	case TMPNAME:
	return valueOf(tmpname());
	}
	return NONE;
	} catch (IOException e) {
	return varargsOf(NIL, valueOf(e.getMessage()));
	}
	}
	}

	/**
	* @return an approximation of the amount in seconds of CPU time used by
	* the program. For luaj this simple returns the elapsed time since the
	* OsLib class was loaded.
	*/
	protected double clock() {
	return (System.currentTimeMillis() - t0) / 1000.;
	}

	/**
	* Returns the number of seconds from time t1 to time t2.
	* In POSIX, Windows, and some other systems, this value is exactly t2-t1.
	* @param t2
	* @param t1
	* @return diffeence in time values, in seconds
	*/
	protected double difftime(double t2, double t1) {
	return t2 - t1;
	}

	/**
	* If the time argument is present, this is the time to be formatted
	* (see the os.time function for a description of this value).
	* Otherwise, date formats the current time.
	*
	* Date returns the date as a string,
	* formatted according to the same rules as ANSII strftime, but without
	* support for %g, %G, or %V.
	*
	* When called without arguments, date returns a reasonable date and
	* time representation that depends on the host system and on the
	* current locale (that is, os.date() is equivalent to os.date("%c")).
	*
	* @param format
	* @param time time since epoch, or -1 if not supplied
	* @return a LString or a LTable containing date and time,
	* formatted according to the given string format.
	*/
	public String date(String format, double time) {
	Calendar d = Calendar.getInstance();
	d.setTime(new Date((long) (time * 1000)));
	if (format.startsWith("!")) {
	time -= timeZoneOffset(d);
	d.setTime(new Date((long) (time * 1000)));
	format = format.substring(1);
	}
	byte[] fmt = format.getBytes();
	final int n = fmt.length;
	Buffer result = new Buffer(n);
	byte c;
	for (int i = 0; i < n;) {
	switch (c = fmt[i++]) {
	case '\n':
	result.append("\n");
	break;
	default:
	result.append(c);
	break;
	case '%':
	if (i >= n)
	break;
	switch (c = fmt[i++]) {
	default:
	LuaValue.argerror(1, "invalid conversion specifier '%" + (char)c + "'");
	break;
	case '%':
	result.append((byte) '%');
	break;
	case 'a':
	result.append(WeekdayNameAbbrev[d.get(Calendar.DAY_OF_WEEK) - 1]);
	break;
	case 'A':
	result.append(WeekdayName[d.get(Calendar.DAY_OF_WEEK) - 1]);
	break;
	case 'b':
	result.append(MonthNameAbbrev[d.get(Calendar.MONTH)]);
	break;
	case 'B':
	result.append(MonthName[d.get(Calendar.MONTH)]);
	break;
	case 'c':
	result.append(date("%a %b %d %H:%M:%S %Y", time));
	break;
	case 'd':
	result.append(String.valueOf(100 + d.get(Calendar.DAY_OF_MONTH)).substring(1));
	break;
	case 'H':
	result.append(String.valueOf(100 + d.get(Calendar.HOUR_OF_DAY)).substring(1));
	break;
	case 'I':
	result.append(String.valueOf(100 + (d.get(Calendar.HOUR_OF_DAY) % 12)).substring(1));
	break;
	case 'j': { // day of year.
	Calendar y0 = beginningOfYear(d);
	int dayOfYear = (int) ((d.getTime().getTime() - y0.getTime().getTime()) / (24 * 3600L * 1000L));
	result.append(String.valueOf(1001 + dayOfYear).substring(1));
	break;
	}
	case 'm':
	result.append(String.valueOf(101 + d.get(Calendar.MONTH)).substring(1));
	break;
	case 'M':
	result.append(String.valueOf(100 + d.get(Calendar.MINUTE)).substring(1));
	break;
	case 'p':
	result.append(d.get(Calendar.HOUR_OF_DAY) < 12 ? "AM" : "PM");
	break;
	case 'S':
	result.append(String.valueOf(100 + d.get(Calendar.SECOND)).substring(1));
	break;
	case 'U':
	result.append(String.valueOf(weekNumber(d, 0)));
	break;
	case 'w':
	result.append(String.valueOf((d.get(Calendar.DAY_OF_WEEK) + 6) % 7));
	break;
	case 'W':
	result.append(String.valueOf(weekNumber(d, 1)));
	break;
	case 'x':
	result.append(date("%m/%d/%y", time));
	break;
	case 'X':
	result.append(date("%H:%M:%S", time));
	break;
	case 'y':
	result.append(String.valueOf(d.get(Calendar.YEAR)).substring(2));
	break;
	case 'Y':
	result.append(String.valueOf(d.get(Calendar.YEAR)));
	break;
	case 'z': {
	final int tzo = timeZoneOffset(d) / 60;
	final int a = Math.abs(tzo);
	final String h = String.valueOf(100 + a / 60).substring(1);
	final String m = String.valueOf(100 + a % 60).substring(1);
	result.append((tzo >= 0 ? "+" : "-") + h + m);
	break;
	}
	}
	}
	}
	return result.tojstring();
	}

	private static final String[] WeekdayNameAbbrev = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
	private static final String[] WeekdayName = { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" };
	private static final String[] MonthNameAbbrev = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
	private static final String[] MonthName = { "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" };

	private Calendar beginningOfYear(Calendar d) {
	Calendar y0 = Calendar.getInstance();
	y0.setTime(d.getTime());
	y0.set(Calendar.MONTH, 0);
	y0.set(Calendar.DAY_OF_MONTH, 1);
	y0.set(Calendar.HOUR_OF_DAY, 0);
	y0.set(Calendar.MINUTE, 0);
	y0.set(Calendar.SECOND, 0);
	y0.set(Calendar.MILLISECOND, 0);
	return y0;
	}

	private int weekNumber(Calendar d, int startDay) {
	Calendar y0 = beginningOfYear(d);
	y0.set(Calendar.DAY_OF_MONTH, 1 + (startDay + 8 - y0.get(Calendar.DAY_OF_WEEK)) % 7);
	if (y0.after(d)) {
	y0.set(Calendar.YEAR, y0.get(Calendar.YEAR) - 1);
	y0.set(Calendar.DAY_OF_MONTH, 1 + (startDay + 8 - y0.get(Calendar.DAY_OF_WEEK)) % 7);
	}
	long dt = d.getTime().getTime() - y0.getTime().getTime();
	return 1 + (int) (dt / (7L * 24L * 3600L * 1000L));
	}

	private int timeZoneOffset(Calendar d) {
	int localStandarTimeMillis = (d.get(Calendar.HOUR_OF_DAY) * 3600 + d.get(Calendar.MINUTE) * 60 + d.get(Calendar.SECOND)) * 1000;
	return d.getTimeZone().getOffset(1, d.get(Calendar.YEAR), d.get(Calendar.MONTH), d.get(Calendar.DAY_OF_MONTH), d.get(Calendar.DAY_OF_WEEK), localStandarTimeMillis) / 1000;
	}

	private boolean isDaylightSavingsTime(Calendar d) {
	return timeZoneOffset(d) != d.getTimeZone().getRawOffset() / 1000;
	}

	/**
	* This function is equivalent to the C function system.
	* It passes command to be executed by an operating system shell.
	* It returns a status code, which is system-dependent.
	* If command is absent, then it returns nonzero if a shell
	* is available and zero otherwise.
	* @param command command to pass to the system
	*/
	protected Varargs execute(String command) {
	return varargsOf(NIL, valueOf("exit"), ONE);
	}

	/**
	* Calls the C function exit, with an optional code, to terminate the host program.
	* @param code
	*/
	protected void exit(int code) {
	System.exit(code);
	}

	/**
	* Returns the value of the process environment variable varname,
	* or null if the variable is not defined.
	* @param varname
	* @return String value, or null if not defined
	*/
	protected String getenv(String varname) {
	return System.getProperty(varname);
	}

	/**
	* Deletes the file or directory with the given name.
	* Directories must be empty to be removed.
	* If this function fails, it throws and IOException
	*
	* @param filename
	* @throws IOException if it fails
	*/
	protected void remove(String filename) throws IOException {
	throw new IOException("not implemented");
	}

	/**
	* Renames file or directory named oldname to newname.
	* If this function fails,it throws and IOException
	*
	* @param oldname old file name
	* @param newname new file name
	* @throws IOException if it fails
	*/
	protected void rename(String oldname, String newname) throws IOException {
	throw new IOException("not implemented");
	}

	/**
	* Sets the current locale of the program. locale is a string specifying
	* a locale; category is an optional string describing which category to change:
	* "all", "collate", "ctype", "monetary", "numeric", or "time"; the default category
	* is "all".
	*
	* If locale is the empty string, the current locale is set to an implementation-
	* defined native locale. If locale is the string "C", the current locale is set
	* to the standard C locale.
	*
	* When called with null as the first argument, this function only returns the
	* name of the current locale for the given category.
	*
	* @param locale
	* @param category
	* @return the name of the new locale, or null if the request
	* cannot be honored.
	*/
	protected String setlocale(String locale, String category) {
	return "C";
	}

	/**
	* Returns the current time when called without arguments,
	* or a time representing the date and time specified by the given table.
	* This table must have fields year, month, and day,
	* and may have fields hour, min, sec, and isdst
	* (for a description of these fields, see the os.date function).
	* @param table
	* @return long value for the time
	*/
	protected double time(LuaTable table) {
	java.util.Date d;
	if (table == null) {
	d = new java.util.Date();
	} else {
	Calendar c = Calendar.getInstance();
	c.set(Calendar.YEAR, table.get("year").checkint());
	c.set(Calendar.MONTH, table.get("month").checkint() - 1);
	c.set(Calendar.DAY_OF_MONTH, table.get("day").checkint());
	c.set(Calendar.HOUR, table.get("hour").optint(12));
	c.set(Calendar.MINUTE, table.get("min").optint(0));
	c.set(Calendar.SECOND, table.get("sec").optint(0));
	c.set(Calendar.MILLISECOND, 0);
	d = c.getTime();
	}
	return d.getTime() / 1000.;
	}

	/**
	* Returns a string with a file name that can be used for a temporary file.
	* The file must be explicitly opened before its use and explicitly removed
	* when no longer needed.
	*
	* On some systems (POSIX), this function also creates a file with that name,
	* to avoid security risks. (Someone else might create the file with wrong
	* permissions in the time between getting the name and creating the file.)
	* You still have to open the file to use it and to remove it (even if you
	* do not use it).
	*
	* @return String filename to use
	*/
	protected String tmpname() {
	synchronized (OsLib.class) {
	return TMP_PREFIX + (tmpnames++) + TMP_SUFFIX;
	}
	}
	}