/*
 
* Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
 
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 
*
 
* This code is free software; you can redistribute it and/or modify it
 
* under the terms of the GNU General Public License version 2 only, as
 
* published by the Free Software Foundation.
  
Oracle designates this
 
* particular file as subject to the "Classpath" exception as provided
 
* by Oracle in the LICENSE file that accompanied this code.
 
*
 
* This code is distributed in the hope that it will be useful, but WITHOUT
 
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 
* FITNESS FOR A PARTICULAR PURPOSE.
  
See the GNU General Public License
 
* version 2 for more details (a copy is included in the LICENSE file that
 
* accompanied this code).
 
*
 
* You should have received a copy of the GNU General Public License version
 
* 2 along with this work; if not, write to the Free Software Foundation,
 
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 
*
 
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 
* or visit www.oracle.com if you need additional information or have any
 
* questions.
 
*/
package java.lang;

import java.io.*;
import java.lang.reflect.Executable;
import java.lang.annotation.Annotation;
import java.security.AccessControlContext;
import java.util.Properties;
import java.util.PropertyPermission;
import java.util.StringTokenizer;
import java.util.Map;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.AllPermission;
import java.nio.channels.Channel;
import java.nio.channels.spi.SelectorProvider;
import sun.nio.ch.Interruptible;
import sun.reflect.CallerSensitive;
import sun.reflect.Reflection;
import sun.security.util.SecurityConstants;
import sun.reflect.annotation.AnnotationType;

/**
 
* The <code>System</code> class contains several useful class fields
 
* and methods. It cannot be instantiated.
 
*
 
* <p>Among the facilities provided by the <code>System</code> class
 
* are standard input, standard output, and error output streams;
 
* access to externally defined properties and environment
 
* variables; a means of loading files and libraries; and a utility
 
* method for quickly copying a portion of an array.
 
*
 
* @author
  
unascribed
 
* @since
   
JDK1.0
 
*/

public final class System {

    
/* register the natives via the static initializer.
     
*
     
* VM will invoke the initializeSystemClass method to complete
     
* the initialization for this class separated from clinit.
     
* Note that to use properties set by the VM, see the constraints
     
* described in the initializeSystemClass method.
     
*/

    
private static native void registerNatives();
    
static {
        
registerNatives();
    
}

    
/** Don't let anyone instantiate this class */
    
private System() {
    
}

    
/**
     
* The "standard" input stream. This stream is already
     
* open and ready to supply input data. Typically this stream
     
* corresponds to keyboard input or another input source specified by
     
* the host environment or user.
     
*/

    
public final static InputStream in = null;

    
/**
     
* The "standard" output stream. This stream is already
     
* open and ready to accept output data. Typically this stream
     
* corresponds to display output or another output destination
     
* specified by the host environment or user.
     
* <p>
     
* For simple stand-alone Java applications, a typical way to write
     
* a line of output data is:
     
* <blockquote><pre>
     
*System.out.println(data)
     
* </pre></blockquote>
     
* <p>
     
* See the <code>println</code> methods in class <code>PrintStream</code>.
     
*
     
* @seejava.io.PrintStream#println()
     
* @seejava.io.PrintStream#println(boolean)
     
* @seejava.io.PrintStream#println(char)
     
* @seejava.io.PrintStream#println(char[])
     
* @seejava.io.PrintStream#println(double)
     
* @seejava.io.PrintStream#println(float)
     
* @seejava.io.PrintStream#println(int)
     
* @seejava.io.PrintStream#println(long)
     
* @seejava.io.PrintStream#println(java.lang.Object)
     
* @seejava.io.PrintStream#println(java.lang.String)
     
*/

    
public final static PrintStream out = null;

    
/**
     
* The "standard" error output stream. This stream is already
     
* open and ready to accept output data.
     
* <p>
     
* Typically this stream corresponds to display output or another
     
* output destination specified by the host environment or user. By
     
* convention, this output stream is used to display error messages
     
* or other information that should come to the immediate attention
     
* of a user even if the principal output stream, the value of the
     
* variable <code>out</code>, has been redirected to a file or other
     
* destination that is typically not continuously monitored.
     
*/

    
public final static PrintStream err = null;

    
/* The security manager for the system.
     
*/
    
private static volatile SecurityManager security = null;

    
/**
     
* Reassigns the "standard" input stream.
     
*
     
* <p>First, if there is a security manager, its <code>checkPermission</code>
     
* method is called with a <code>RuntimePermission("setIO")</code> permission
     
*
  
to see if it's ok to reassign the "standard" input stream.
     
* <p>
     
*
     
* @param in the new standard input stream.
     
*
     
* @throws SecurityException
     
*
        
if a security manager exists and its
     
*
        
<code>checkPermission</code> method doesn't allow
     
*
        
reassigning of the standard input stream.
     
*
     
* @see SecurityManager#checkPermission
     
*
 

     
*
     
* @since
   
JDK1.1
     
*/

    
public static void setIn(InputStream in) {
        
checkIO();
        
setIn0(in);
    
}

    
/**
     
* Reassigns the "standard" output stream.
     
*
     
* <p>First, if there is a security manager, its <code>checkPermission</code>
     
* method is called with a <code>RuntimePermission("setIO")</code> permission
     
*
  
to see if it's ok to reassign the "standard" output stream.
     
*
     
* @param out the new standard output stream
     
*
     
* @throws SecurityException
     
*
        
if a security manager exists and its
     
*
        
<code>checkPermission</code> method doesn't allow
     
*
        
reassigning of the standard output stream.
     
*
     
* @see SecurityManager#checkPermission
     
*
 

     
*
     
* @since
   
JDK1.1
     
*/

    
public static void setOut(PrintStream out) {
        
checkIO();
        
setOut0(out);
    
}

    
/**
     
* Reassigns the "standard" error output stream.
     
*
     
* <p>First, if there is a security manager, its <code>checkPermission</code>
     
* method is called with a <code>RuntimePermission("setIO")</code> permission
     
*
  
to see if it's ok to reassign the "standard" error output stream.
     
*
     
* @param err the new standard error output stream.
     
*
     
* @throws SecurityException
     
*
        
if a security manager exists and its
     
*
        
<code>checkPermission</code> method doesn't allow
     
*
        
reassigning of the standard error output stream.
     
*
     
* @see SecurityManager#checkPermission
     
*
 

     
*
     
* @since
   
JDK1.1
     
*/

    
public static void setErr(PrintStream err) {
        
checkIO();
        
setErr0(err);
    
}

    
private static volatile Console cons = null;
    
/**
     
* Returns the unique {@link java.io.Console Console} object associated
     
* with the current Java virtual machine, if any.
     
*
     
* @return
  
The system console, if any, otherwise <tt>null</tt>.
     
*
     
* @since
   
1.6
     
*/

     
public static Console console() {
         
if (cons == null) {
             
synchronized (System.class) {
                 
cons = sun.misc.SharedSecrets.getJavaIOAccess().console();
             
}
         
}
         
return cons;
     
}

    
/**
     
* Returns the channel inherited from the entity that created this
     
* Java virtual machine.
     
*
     
* <p> This method returns the channel obtained by invoking the
     
* {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
     
* inheritedChannel} method of the system-wide default
     
*
 
 
object. </p>
     
*
     
* <p> In addition to the network-oriented channels described in
     
* {@link java.nio.channels.spi.SelectorProvider#inheritedChannel
     
* inheritedChannel}, this method may return other kinds of
     
* channels in the future.
     
*
     
* @return
  
The inherited channel, if any, otherwise <tt>null</tt>.
     
*
     
* @throws
  
IOException
     
*
          
If an I/O error occurs
     
*
     
* @throws
  
SecurityException
     
*
          
If a security manager is present and it does not
     
*
          
permit access to the channel.
     
*
     
* @since 1.5
     
*/

    
public static Channel inheritedChannel() throws IOException {
        
return SelectorProvider.provider().inheritedChannel();
    
}

    
private static void checkIO() {
        
SecurityManager sm = getSecurityManager();
        
if (sm != null) {
            
sm.checkPermission(new RuntimePermission("setIO"));
        
}
    
}

    
private static native void setIn0(InputStream in);
    
private static native void setOut0(PrintStream out);
    
private static native void setErr0(PrintStream err);

    
/**
     
* Sets the System security.
     
*
     
* <p> If there is a security manager already installed, this method first
     
* calls the security manager's <code>checkPermission</code> method
     
* with a <code>RuntimePermission("setSecurityManager")</code>
     
* permission to ensure it's ok to replace the existing
     
* security manager.
     
* This may result in throwing a <code>SecurityException</code>.
     
*
     
* <p> Otherwise, the argument is established as the current
     
* security manager. If the argument is <code>null</code> and no
     
* security manager has been established, then no action is taken and
     
* the method simply returns.
     
*
     
* @param
      
s
   
the security manager.
     
* @exception
  
SecurityExceptionif the security manager has already
     
*
             
been set and its <code>checkPermission</code> method
     
*
             
doesn't allow it to be replaced.
     
* @see #getSecurityManager
     
* @see SecurityManager#checkPermission
     
*
 

     
*/

    
public static
    
void
setSecurityManager(final SecurityManager s) {
        
try {
            
s.checkPackageAccess("java.lang");
        
} catch (Exception e) {
            
// no-op
        
}
        
setSecurityManager0(s);
    
}

    
private static synchronized
    
void
setSecurityManager0(final SecurityManager s) {
        
SecurityManager sm = getSecurityManager();
        
if (sm != null) {
            
// ask the currently installed security manager if we
            
// can replace it.
            
sm.checkPermission(new RuntimePermission
                                     
("setSecurityManager"));
        
}

        
if ((s != null) && (s.getClass().getClassLoader() != null)) {
            
// New security manager class is not on bootstrap classpath.
            
// Cause policy to get initialized before we install the new
            
// security manager, in order to prevent infinite loops when
            
// trying to initialize the policy (which usually involves
            
// accessing some security and/or system properties, which in turn
            
// calls the installed security manager's checkPermission method
            
// which will loop infinitely if there is a non-system class
            
// (in this case: the new security manager class) on the stack).
            
AccessController.doPrivileged(new PrivilegedAction<Object>() {
                
public Object run() {
                    
s.getClass().getProtectionDomain().implies
                        
(SecurityConstants.ALL_PERMISSION);
                    
return null;
                
}
            
});
        
}

        
security = s;
    
}

    
/**
     
* Gets the system security interface.
     
*
     
* @return
  
if a security manager has already been established for the
     
*
          
current application, then that security manager is returned;
     
*
          
otherwise, <code>null</code> is returned.
     
* @see#setSecurityManager
     
*/

    
public static SecurityManager getSecurityManager() {
        
return security;
    
}

    
/**
     
* Returns the current time in milliseconds.
  
Note that
     
* while the unit of time of the return value is a millisecond,
     
* the granularity of the value depends on the underlying
     
* operating system and may be larger.
  
For example, many
     
* operating systems measure time in units of tens of
     
* milliseconds.
     
*
     
* <p> See the description of the class <code>Date</code> for
     
* a discussion of slight discrepancies that may arise between
     
* "computer time" and coordinated universal time (UTC).
     
*
     
* @return
  
the difference, measured in milliseconds, between
     
*
          
the current time and midnight, January 1, 1970 UTC.
     
* @seejava.util.Date
     
*/

    
public static native long currentTimeMillis();

    
/**
     
* Returns the current value of the running Java Virtual Machine's
     
* high-resolution time source, in nanoseconds.
     
*
     
* <p>This method can only be used to measure elapsed time and is
     
* not related to any other notion of system or wall-clock time.
     
* The value returned represents nanoseconds since some fixed but
     
* arbitrary <i>origin</i> time (perhaps in the future, so values
     
* may be negative).
  
The same origin is used by all invocations of
     
* this method in an instance of a Java virtual machine; other
     
* virtual machine instances are likely to use a different origin.
     
*
     
* <p>This method provides nanosecond precision, but not necessarily
     
* nanosecond resolution (that is, how frequently the value changes)
     
* - no guarantees are made except that the resolution is at least as
     
* good as that of
 
.
     
*
     
* <p>Differences in successive calls that span greater than
     
* approximately 292 years (2<sup>63</sup> nanoseconds) will not
     
* correctly compute elapsed time due to numerical overflow.
     
*
     
* <p>The values returned by this method become meaningful only when
     
* the difference between two such values, obtained within the same
     
* instance of a Java virtual machine, is computed.
     
*
     
* <p> For example, to measure how long some code takes to execute:
     
*
  
<pre> {@code
     
* long startTime = System.nanoTime();
     
* // ... the code being measured ...
     
* long estimatedTime = System.nanoTime() - startTime;}</pre>
     
*
     
* <p>To compare two nanoTime values
     
*
  
<pre> {@code
     
* long t0 = System.nanoTime();
     
* ...
     
* long t1 = System.nanoTime();}</pre>
     
*
     
* one should use {@code t1 - t0 < 0}, not {@code t1 < t0},
     
* because of the possibility of numerical overflow.
     
*
     
* @return the current value of the running Java Virtual Machine's
     
*
         
high-resolution time source, in nanoseconds
     
* @since 1.5
     
*/

    
public static native long nanoTime();

    
/**
     
* Copies an array from the specified source array, beginning at the
     
* specified position, to the specified position of the destination array.
     
* A subsequence of array components are copied from the source
     
* array referenced by <code>src</code> to the destination array
     
* referenced by <code>dest</code>. The number of components copied is
     
* equal to the <code>length</code> argument. The components at
     
* positions <code>srcPos</code> through
     
* <code>srcPos+length-1</code> in the source array are copied into
     
* positions <code>destPos</code> through
     
* <code>destPos+length-1</code>, respectively, of the destination
     
* array.
     
* <p>
     
* If the <code>src</code> and <code>dest</code> arguments refer to the
     
* same array object, then the copying is performed as if the
     
* components at positions <code>srcPos</code> through
     
* <code>srcPos+length-1</code> were first copied to a temporary
     
* array with <code>length</code> components and then the contents of
     
* the temporary array were copied into positions
     
* <code>destPos</code> through <code>destPos+length-1</code> of the
     
* destination array.
     
* <p>
     
* If <code>dest</code> is <code>null</code>, then a
     
* <code>NullPointerException</code> is thrown.
     
* <p>
     
* If <code>src</code> is <code>null</code>, then a
     
* <code>NullPointerException</code> is thrown and the destination
     
* array is not modified.
     
* <p>
     
* Otherwise, if any of the following is true, an
     
* <code>ArrayStoreException</code> is thrown and the destination is
     
* not modified:
     
* <ul>
     
* <li>The <code>src</code> argument refers to an object that is not an
     
*array.
     
* <li>The <code>dest</code> argument refers to an object that is not an
     
*array.
     
* <li>The <code>src</code> argument and <code>dest</code> argument refer
     
*to arrays whose component types are different primitive types.
     
* <li>The <code>src</code> argument refers to an array with a primitive
     
*
    
component type and the <code>dest</code> argument refers to an array
     
*with a reference component type.
     
* <li>The <code>src</code> argument refers to an array with a reference
     
*
    
component type and the <code>dest</code> argument refers to an array
     
*with a primitive component type.
     
* </ul>
     
* <p>
     
* Otherwise, if any of the following is true, an
     
* <code>IndexOutOfBoundsException</code> is
     
* thrown and the destination is not modified:
     
* <ul>
     
* <li>The <code>srcPos</code> argument is negative.
     
* <li>The <code>destPos</code> argument is negative.
     
* <li>The <code>length</code> argument is negative.
     
* <li><code>srcPos+length</code> is greater than
     
*<code>src.length</code>, the length of the source array.
     
* <li><code>destPos+length</code> is greater than
     
*<code>dest.length</code>, the length of the destination array.
     
* </ul>
     
* <p>
     
* Otherwise, if any actual component of the source array from
     
* position <code>srcPos</code> through
     
* <code>srcPos+length-1</code> cannot be converted to the component
     
* type of the destination array by assignment conversion, an
     
* <code>ArrayStoreException</code> is thrown. In this case, let
     
* <b><i>k</i></b> be the smallest nonnegative integer less than
     
* length such that <code>src[srcPos+</code><i>k</i><code>]</code>
     
* cannot be converted to the component type of the destination
     
* array; when the exception is thrown, source array components from
     
* positions <code>srcPos</code> through
     
* <code>srcPos+</code><i>k</i><code>-1</code>
     
* will already have been copied to destination array positions
     
* <code>destPos</code> through
     
* <code>destPos+</code><i>k</I><code>-1</code> and no other
     
* positions of the destination array will have been modified.
     
* (Because of the restrictions already itemized, this
     
* paragraph effectively applies only to the situation where both
     
* arrays have component types that are reference types.)
     
*
     
* @param
      
srcthe source array.
     
* @param
      
srcPos
   
starting position in the source array.
     
* @param
      
destthe destination array.
     
* @param
      
destPos
  
starting position in the destination data.
     
* @param
      
length
   
the number of array elements to be copied.
     
* @exception
  
IndexOutOfBoundsExceptionif copying would cause
     
*
               
access of data outside array bounds.
     
* @exception
  
ArrayStoreExceptionif an element in the <code>src</code>
     
*
               
array could not be stored into the <code>dest</code> array
     
*
               
because of a type mismatch.
     
* @exception
  
NullPointerException if either <code>src</code> or
     
*
               
<code>dest</code> is <code>null</code>.
     
*/

    
public static native void arraycopy(Object src,
  
int
  
srcPos,
                                        
Object dest, int destPos,
                                        
int length);

    
/**
     
* Returns the same hash code for the given object as
     
* would be returned by the default method hashCode(),
     
* whether or not the given object's class overrides
     
* hashCode().
     
* The hash code for the null reference is zero.
     
*
     
* @param x object for which the hashCode is to be calculated
     
* @return
  
the hashCode
     
* @since
   
JDK1.1
     
*/

    
public static native int identityHashCode(Object x);

    
/**
     
* System properties. The following properties are guaranteed to be defined:
     
* <dl>
     
* <dt>java.version
         
<dd>Java version number
     
* <dt>java.vendor
          
<dd>Java vendor specific string
     
* <dt>java.vendor.url
      
<dd>Java vendor URL
     
* <dt>java.home
            
<dd>Java installation directory
     
* <dt>java.class.version
   
<dd>Java class version number
     
* <dt>java.class.path
      
<dd>Java classpath
     
* <dt>os.name
              
<dd>Operating System Name
     
* <dt>os.arch
              
<dd>Operating System Architecture
     
* <dt>os.version
           
<dd>Operating System Version
     
* <dt>file.separator
       
<dd>File separator ("/" on Unix)
     
* <dt>path.separator
       
<dd>Path separator (":" on Unix)
     
* <dt>line.separator
       
<dd>Line separator ("\n" on Unix)
     
* <dt>user.name
            
<dd>User account name
     
* <dt>user.home
            
<dd>User home directory
     
* <dt>user.dir
             
<dd>User's current working directory
     
* </dl>
     
*/


    
private static Properties props;
    
private static native Properties initProperties(Properties props);

    
/**
     
* Determines the current system properties.
     
* <p>
     
* First, if there is a security manager, its
     
* <code>checkPropertiesAccess</code> method is called with no
     
* arguments. This may result in a security exception.
     
* <p>
     
* The current set of system properties for use by the
     
* {@link #getProperty(String)} method is returned as a
     
* <code>Properties</code> object. If there is no current set of
     
* system properties, a set of system properties is first created and
     
* initialized. This set of system properties always includes values
     
* for the following keys:
     
* <table summary="Shows property keys and associated values">
     
* <tr><th>Key</th>
     
*<th>Description of Associated Value</th></tr>
     
* <tr><td><code>java.version</code></td>
     
*<td>Java Runtime Environment version</td></tr>
     
* <tr><td><code>java.vendor</code></td>
     
*<td>Java Runtime Environment vendor</td></tr>
     
* <tr><td><code>java.vendor.url</code></td>
     
*<td>Java vendor URL</td></tr>
     
* <tr><td><code>java.home</code></td>
     
*<td>Java installation directory</td></tr>
     
* <tr><td><code>java.vm.specification.version</code></td>
     
*<td>Java Virtual Machine specification version</td></tr>
     
* <tr><td><code>java.vm.specification.vendor</code></td>
     
*<td>Java Virtual Machine specification vendor</td></tr>
     
* <tr><td><code>java.vm.specification.name</code></td>
     
*<td>Java Virtual Machine specification name</td></tr>
     
* <tr><td><code>java.vm.version</code></td>
     
*<td>Java Virtual Machine implementation version</td></tr>
     
* <tr><td><code>java.vm.vendor</code></td>
     
*<td>Java Virtual Machine implementation vendor</td></tr>
     
* <tr><td><code>java.vm.name</code></td>
     
*<td>Java Virtual Machine implementation name</td></tr>
     
* <tr><td><code>java.specification.version</code></td>
     
*<td>Java Runtime Environment specification
  
version</td></tr>
     
* <tr><td><code>java.specification.vendor</code></td>
     
*<td>Java Runtime Environment specification
  
vendor</td></tr>
     
* <tr><td><code>java.specification.name</code></td>
     
*<td>Java Runtime Environment specification
  
name</td></tr>
     
* <tr><td><code>java.class.version</code></td>
     
*<td>Java class format version number</td></tr>
     
* <tr><td><code>java.class.path</code></td>
     
*<td>Java class path</td></tr>
     
* <tr><td><code>java.library.path</code></td>
     
*<td>List of paths to search when loading libraries</td></tr>
     
* <tr><td><code>java.io.tmpdir</code></td>
     
*<td>Default temp file path</td></tr>
     
* <tr><td><code>java.compiler</code></td>
     
*<td>Name of JIT compiler to use</td></tr>
     
* <tr><td><code>java.ext.dirs</code></td>
     
*<td>Path of extension directory or directories
     
*
         
<b>Deprecated.</b> <i>This property, and the mechanism
     
*
            
which implements it, may be removed in a future
     
*
            
release.</i> </td></tr>
     
* <tr><td><code>os.name</code></td>
     
*<td>Operating system name</td></tr>
     
* <tr><td><code>os.arch</code></td>
     
*<td>Operating system architecture</td></tr>
     
* <tr><td><code>os.version</code></td>
     
*<td>Operating system version</td></tr>
     
* <tr><td><code>file.separator</code></td>
     
*<td>File separator ("/" on UNIX)</td></tr>
     
* <tr><td><code>path.separator</code></td>
     
*<td>Path separator (":" on UNIX)</td></tr>
     
* <tr><td><code>line.separator</code></td>
     
*<td>Line separator ("\n" on UNIX)</td></tr>
     
* <tr><td><code>user.name</code></td>
     
*<td>User's account name</td></tr>
     
* <tr><td><code>user.home</code></td>
     
*<td>User's home directory</td></tr>
     
* <tr><td><code>user.dir</code></td>
     
*<td>User's current working directory</td></tr>
     
* </table>
     
* <p>
     
* Multiple paths in a system property value are separated by the path
     
* separator character of the platform.
     
* <p>
     
* Note that even if the security manager does not permit the
     
* <code>getProperties</code> operation, it may choose to permit the
     
* {@link #getProperty(String)} operation.
     
*
     
* @returnthe system properties
     
* @exception
  
SecurityExceptionif a security manager exists and its
     
*
             
<code>checkPropertiesAccess</code> method doesn't allow access
     
*
              
to the system properties.
     
* @see
        
#setProperties
     
* @see
        
java.lang.SecurityException
     
* @see
        
java.lang.SecurityManager#checkPropertiesAccess()
     
* @see
        
java.util.Properties
     
*/

    
public static Properties getProperties() {
        
SecurityManager sm = getSecurityManager();
        
if (sm != null) {
            
sm.checkPropertiesAccess();
        
}

        
return props;
    
}

    
/**
     
* Returns the system-dependent line separator string.
  
It always
     
* returns the same value - the initial value of the {@linkplain
     
* #getProperty(String) system property} {@code line.separator}.
     
*
     
* <p>On UNIX systems, it returns {@code "\n"}; on Microsoft
     
* Windows systems it returns {@code "\r\n"}.
     
*
     
* @return the system-dependent line separator string
     
* @since 1.7
     
*/

    
public static String lineSeparator() {
        
return lineSeparator;
    
}

    
private static String lineSeparator;

    
/**
     
* Sets the system properties to the <code>Properties</code>
     
* argument.
     
* <p>
     
* First, if there is a security manager, its
     
* <code>checkPropertiesAccess</code> method is called with no
     
* arguments. This may result in a security exception.
     
* <p>
     
* The argument becomes the current set of system properties for use
     
* by the {@link #getProperty(String)} method. If the argument is
     
* <code>null</code>, then the current set of system properties is
     
* forgotten.
     
*
     
* @param
      
props
   
the new system properties.
     
* @exception
  
SecurityExceptionif a security manager exists and its
     
*
             
<code>checkPropertiesAccess</code> method doesn't allow access
     
*
              
to the system properties.
     
* @see
        
#getProperties
     
* @see
        
java.util.Properties
     
* @see
        
java.lang.SecurityException
     
* @see
        
java.lang.SecurityManager#checkPropertiesAccess()
     
*/

    
public static void setProperties(Properties props) {
        
SecurityManager sm = getSecurityManager();
        
if (sm != null) {
            
sm.checkPropertiesAccess();
        
}
        
if (props == null) {
            
props = new Properties();
            
initProperties(props);
        
}
        
System.props = props;
    
}

    
/**
     
* Gets the system property indicated by the specified key.
     
* <p>
     
* First, if there is a security manager, its
     
* <code>checkPropertyAccess</code> method is called with the key as
     
* its argument. This may result in a SecurityException.
     
* <p>
     
* If there is no current set of system properties, a set of system
     
* properties is first created and initialized in the same manner as
     
* for the <code>getProperties</code> method.
     
*
     
* @param
      
key
   
the name of the system property.
     
* @returnthe string value of the system property,
     
*
             
or <code>null</code> if there is no property with that key.
     
*
     
* @exception
  
SecurityExceptionif a security manager exists and its
     
*
             
<code>checkPropertyAccess</code> method doesn't allow
     
*
              
access to the specified system property.
     
* @exception
  
NullPointerException if <code>key</code> is
     
*
             
<code>null</code>.
     
* @exception
  
IllegalArgumentException if <code>key</code> is empty.
     
* @see
        
#setProperty
     
* @see
        
java.lang.SecurityException
     
* @see
        
java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
     
* @see
        
java.lang.System#getProperties()
     
*/

    
public static String getProperty(String key) {
        
checkKey(key);
        
SecurityManager sm = getSecurityManager();
        
if (sm != null) {
            
sm.checkPropertyAccess(key);
        
}

        
return props.getProperty(key);
    
}

    
/**
     
* Gets the system property indicated by the specified key.
     
* <p>
     
* First, if there is a security manager, its
     
* <code>checkPropertyAccess</code> method is called with the
     
* <code>key</code> as its argument.
     
* <p>
     
* If there is no current set of system properties, a set of system
     
* properties is first created and initialized in the same manner as
     
* for the <code>getProperties</code> method.
     
*
     
* @param
      
key
   
the name of the system property.
     
* @param
      
def
   
a default value.
     
* @returnthe string value of the system property,
     
*
             
or the default value if there is no property with that key.
     
*
     
* @exception
  
SecurityExceptionif a security manager exists and its
     
*
             
<code>checkPropertyAccess</code> method doesn't allow
     
*
             
access to the specified system property.
     
* @exception
  
NullPointerException if <code>key</code> is
     
*
             
<code>null</code>.
     
* @exception
  
IllegalArgumentException if <code>key</code> is empty.
     
* @see
        
#setProperty
     
* @see
        
java.lang.SecurityManager#checkPropertyAccess(java.lang.String)
     
* @see
        
java.lang.System#getProperties()
     
*/

    
public static String getProperty(String key, String def) {
        
checkKey(key);
        
SecurityManager sm = getSecurityManager();
        
if (sm != null) {
            
sm.checkPropertyAccess(key);
        
}

        
return props.getProperty(key, def);
    
}

    
/**
     
* Sets the system property indicated by the specified key.
     
* <p>
     
* First, if a security manager exists, its
     
* <code>SecurityManager.checkPermission</code> method
     
* is called with a <code>PropertyPermission(key, "write")</code>
     
* permission. This may result in a SecurityException being thrown.
     
* If no exception is thrown, the specified property is set to the given
     
* value.
     
* <p>
     
*
     
* @param
      
key
   
the name of the system property.
     
* @param
      
value the value of the system property.
     
* @returnthe previous value of the system property,
     
*
             
or <code>null</code> if it did not have one.
     
*
     
* @exception
  
SecurityExceptionif a security manager exists and its
     
*
             
<code>checkPermission</code> method doesn't allow
     
*
             
setting of the specified property.
     
* @exception
  
NullPointerException if <code>key</code> or
     
*
             
<code>value</code> is <code>null</code>.
     
* @exception
  
IllegalArgumentException if <code>key</code> is empty.
     
* @see
        
#getProperty
     
* @see
        
java.lang.System#getProperty(java.lang.String)
     
* @see
        
java.lang.System#getProperty(java.lang.String, java.lang.String)
     
* @see
        
java.util.PropertyPermission
     
* @see
        
SecurityManager#checkPermission
     
* @since
      
1.2
     
*/

    
public static String setProperty(String key, String value) {
        
checkKey(key);
        
SecurityManager sm = getSecurityManager();
        
if (sm != null) {
            
sm.checkPermission(new PropertyPermission(key,
                
SecurityConstants.PROPERTY_WRITE_ACTION));
        
}

        
return (String) props.setProperty(key, value);
    
}

    
/**
     
* Removes the system property indicated by the specified key.
     
* <p>
     
* First, if a security manager exists, its
     
* <code>SecurityManager.checkPermission</code> method
     
* is called with a <code>PropertyPermission(key, "write")</code>
     
* permission. This may result in a SecurityException being thrown.
     
* If no exception is thrown, the specified property is removed.
     
* <p>
     
*
     
* @param
      
key
   
the name of the system property to be removed.
     
* @returnthe previous string value of the system property,
     
*
             
or <code>null</code> if there was no property with that key.
     
*
     
* @exception
  
SecurityExceptionif a security manager exists and its
     
*
             
<code>checkPropertyAccess</code> method doesn't allow
     
*
              
access to the specified system property.
     
* @exception
  
NullPointerException if <code>key</code> is
     
*
             
<code>null</code>.
     
* @exception
  
IllegalArgumentException if <code>key</code> is empty.
     
* @see
        
#getProperty
     
* @see
        
#setProperty
     
* @see
        
java.util.Properties
     
* @see
        
java.lang.SecurityException
     
* @see
        
java.lang.SecurityManager#checkPropertiesAccess()
     
* @since 1.5
     
*/

    
public static String clearProperty(String key) {
        
checkKey(key);
        
SecurityManager sm = getSecurityManager();
        
if (sm != null) {
            
sm.checkPermission(new PropertyPermission(key, "write"));
        
}

        
return (String) props.remove(key);
    
}

    
private static void checkKey(String key) {
        
if (key == null) {
            
throw new NullPointerException("key can't be null");
        
}
        
if (key.equals("")) {
            
throw new IllegalArgumentException("key can't be empty");
        
}
    
}

    
/**
     
* Gets the value of the specified environment variable. An
     
* environment variable is a system-dependent external named
     
* value.
     
*
     
* <p>If a security manager exists, its
     
* {@link SecurityManager#checkPermission checkPermission}
     
* method is called with a
     
* <code>{@link RuntimePermission}("getenv."+name)</code>
     
* permission.
  
This may result in a {@link SecurityException}
     
* being thrown.
  
If no exception is thrown the value of the
     
* variable <code>name</code> is returned.
     
*
     
* <p><a name="EnvironmentVSSystemProperties"><i>System
     
* properties</i> and <i>environment variables</i></a> are both
     
* conceptually mappings between names and values.
  
Both
     
* mechanisms can be used to pass user-defined information to a
     
* Java process.
  
Environment variables have a more global effect,
     
* because they are visible to all descendants of the process
     
* which defines them, not just the immediate Java subprocess.
     
* They can have subtly different semantics, such as case
     
* insensitivity, on different operating systems.
  
For these
     
* reasons, environment variables are more likely to have
     
* unintended side effects.
  
It is best to use system properties
     
* where possible.
  
Environment variables should be used when a
     
* global effect is desired, or when an external system interface
     
* requires an environment variable (such as <code>PATH</code>).
     
*
     
* <p>On UNIX systems the alphabetic case of <code>name</code> is
     
* typically significant, while on Microsoft Windows systems it is
     
* typically not.
  
For example, the expression
     
* <code>System.getenv("FOO").equals(System.getenv("foo"))</code>
     
* is likely to be true on Microsoft Windows.
     
*
     
* @param
  
name the name of the environment variable
     
* @return the string value of the variable, or <code>null</code>
     
*
         
if the variable is not defined in the system environment
     
* @throws NullPointerException if <code>name</code> is <code>null</code>
     
* @throws SecurityException
     
*
         
if a security manager exists and its
     
*
         
{@link SecurityManager#checkPermission checkPermission}
     
*
         
method doesn't allow access to the environment variable
     
*
         
<code>name</code>
     
* @see
    
#getenv()
     
* @see
    
ProcessBuilder#environment()
     
*/

    
public static String getenv(String name) {
        
SecurityManager sm = getSecurityManager();
        
if (sm != null) {
            
sm.checkPermission(new RuntimePermission("getenv."+name));
        
}

        
return ProcessEnvironment.getenv(name);
    
}


    
/**
     
* Returns an unmodifiable string map view of the current system environment.
     
* The environment is a system-dependent mapping from names to
     
* values which is passed from parent to child processes.
     
*
     
* <p>If the system does not support environment variables, an
     
* empty map is returned.
     
*
     
* <p>The returned map will never contain null keys or values.
     
* Attempting to query the presence of a null key or value will
     
* throw a {@link NullPointerException}.
  
Attempting to query
     
* the presence of a key or value which is not of type
     
* {@link String} will throw a {@link ClassCastException}.
     
*
     
* <p>The returned map and its collection views may not obey the
     
* general contract of the {@link Object#equals} and
     
* {@link Object#hashCode} methods.
     
*
     
* <p>The returned map is typically case-sensitive on all platforms.
     
*
     
* <p>If a security manager exists, its
     
* {@link SecurityManager#checkPermission checkPermission}
     
* method is called with a
     
* <code>{@link RuntimePermission}("getenv.*")</code>
     
* permission.
  
This may result in a {@link SecurityException} being
     
* thrown.
     
*
     
* <p>When passing information to a Java subprocess,
     
* <a href=#EnvironmentVSSystemProperties>system properties</a>
     
* are generally preferred over environment variables.
     
*
     
* @return the environment as a map of variable names to values
     
* @throws SecurityException
     
*
         
if a security manager exists and its
     
*
         
{@link SecurityManager#checkPermission checkPermission}
     
*
         
method doesn't allow access to the process environment
     
* @see
    
#getenv(String)
     
* @see
    
ProcessBuilder#environment()
     
* @since
  
1.5
     
*/

    
public static java.util.Map<String,String> getenv() {
        
SecurityManager sm = getSecurityManager();
        
if (sm != null) {
            
sm.checkPermission(new RuntimePermission("getenv.*"));
        
}

        
return ProcessEnvironment.getenv();
    
}

    
/**
     
* Terminates the currently running Java Virtual Machine. The
     
* argument serves as a status code; by convention, a nonzero status
     
* code indicates abnormal termination.
     
* <p>
     
* This method calls the <code>exit</code> method in class
     
* <code>Runtime</code>. This method never returns normally.
     
* <p>
     
* The call <code>System.exit(n)</code> is effectively equivalent to
     
* the call:
     
* <blockquote><pre>
     
* Runtime.getRuntime().exit(n)
     
* </pre></blockquote>
     
*
     
* @param
      
status
   
exit status.
     
* @throws
  
SecurityException
     
*
        
if a security manager exists and its <code>checkExit</code>
     
*
        
method doesn't allow exit with the specified status.
     
* @see
        
java.lang.Runtime#exit(int)
     
*/

    
public static void exit(int status) {
        
Runtime.getRuntime().exit(status);
    
}

    
/**
     
* Runs the garbage collector.
     
* <p>
     
* Calling the <code>gc</code> method suggests that the Java Virtual
     
* Machine expend effort toward recycling unused objects in order to
     
* make the memory they currently occupy available for quick reuse.
     
* When control returns from the method call, the Java Virtual
     
* Machine has made a best effort to reclaim space from all discarded
     
* objects.
     
* <p>
     
* The call <code>System.gc()</code> is effectively equivalent to the
     
* call:
     
* <blockquote><pre>
     
* Runtime.getRuntime().gc()
     
* </pre></blockquote>
     
*
     
* @seejava.lang.Runtime#gc()
     
*/

    
public static void gc() {
        
Runtime.getRuntime().gc();
    
}

    
/**
     
* Runs the finalization methods of any objects pending finalization.
     
* <p>
     
* Calling this method suggests that the Java Virtual Machine expend
     
* effort toward running the <code>finalize</code> methods of objects
     
* that have been found to be discarded but whose <code>finalize</code>
     
* methods have not yet been run. When control returns from the
     
* method call, the Java Virtual Machine has made a best effort to
     
* complete all outstanding finalizations.
     
* <p>
     
* The call <code>System.runFinalization()</code> is effectively
     
* equivalent to the call:
     
* <blockquote><pre>
     
* Runtime.getRuntime().runFinalization()
     
* </pre></blockquote>
     
*
     
* @seejava.lang.Runtime#runFinalization()
     
*/

    
public static void runFinalization() {
        
Runtime.getRuntime().runFinalization();
    
}

    
/**
     
* Enable or disable finalization on exit; doing so specifies that the
     
* finalizers of all objects that have finalizers that have not yet been
     
* automatically invoked are to be run before the Java runtime exits.
     
* By default, finalization on exit is disabled.
     
*
     
* <p>If there is a security manager,
     
* its <code>checkExit</code> method is first called
     
* with 0 as its argument to ensure the exit is allowed.
     
* This could result in a SecurityException.
     
*
     
* @deprecated
  
This method is inherently unsafe.It may result in
     
*
      
finalizers being called on live objects while other threads are
     
*
      
concurrently manipulating those objects, resulting in erratic
     
*
      
behavior or deadlock.
     
* @param value indicating enabling or disabling of finalization
     
* @throws
  
SecurityException
     
*
        
if a security manager exists and its <code>checkExit</code>
     
*
        
method doesn't allow the exit.
     
*
     
* @seejava.lang.Runtime#exit(int)
     
* @seejava.lang.Runtime#gc()
     
* @seejava.lang.SecurityManager#checkExit(int)
     
* @since
   
JDK1.1
     
*/

    
@Deprecated
    
public static void runFinalizersOnExit(boolean value) {
        
Runtime.runFinalizersOnExit(value);
    
}

    
/**
     
* Loads the native library specified by the filename argument.
  
The filename
     
* argument must be an absolute path name.
     
*
     
* If the filename argument, when stripped of any platform-specific library
     
* prefix, path, and file extension, indicates a library whose name is,
     
* for example, L, and a native library called L is statically linked
     
* with the VM, then the JNI_OnLoad_L function exported by the library
     
* is invoked rather than attempting to load a dynamic library.
     
* A filename matching the argument does not have to exist in the
     
* file system.
     
* See the JNI Specification for more details.
     
*
     
* Otherwise, the filename argument is mapped to a native library image in
     
* an implementation-dependent manner.
     
*
     
* <p>
     
* The call <code>System.load(name)</code> is effectively equivalent
     
* to the call:
     
* <blockquote><pre>
     
* Runtime.getRuntime().load(name)
     
* </pre></blockquote>
     
*
     
* @param
      
filename
   
the file to load.
     
* @exception
  
SecurityExceptionif a security manager exists and its
     
*
             
<code>checkLink</code> method doesn't allow
     
*
             
loading of the specified dynamic library
     
* @exception
  
UnsatisfiedLinkErrorif either the filename is not an
     
*
             
absolute path name, the native library is not statically
     
*
             
linked with the VM, or the library cannot be mapped to
     
*
             
a native library image by the host system.
     
* @exception
  
NullPointerException if <code>filename</code> is
     
*
             
<code>null</code>
     
* @see
        
java.lang.Runtime#load(java.lang.String)
     
* @see
        
java.lang.SecurityManager#checkLink(java.lang.String)
     
*/

    
@CallerSensitive
    
public static void load(String filename) {
        
Runtime.getRuntime().load0(Reflection.getCallerClass(), filename);
    
}

    
/**
     
* Loads the native library specified by the <code>libname</code>
     
* argument.
  
The <code>libname</code> argument must not contain any platform
     
* specific prefix, file extension or path. If a native library
     
* called <code>libname</code> is statically linked with the VM, then the
     
* JNI_OnLoad_<code>libname</code> function exported by the library is invoked.
     
* See the JNI Specification for more details.
     
*
     
* Otherwise, the libname argument is loaded from a system library
     
* location and mapped to a native library image in an implementation-
     
* dependent manner.
     
* <p>
     
* The call <code>System.loadLibrary(name)</code> is effectively
     
* equivalent to the call
     
* <blockquote><pre>
     
* Runtime.getRuntime().loadLibrary(name)
     
* </pre></blockquote>
     
*
     
* @param
      
libname
   
the name of the library.
     
* @exception
  
SecurityExceptionif a security manager exists and its
     
*
             
<code>checkLink</code> method doesn't allow
     
*
             
loading of the specified dynamic library
     
* @exception
  
UnsatisfiedLinkError if either the libname argument
     
*
             
contains a file path, the native library is not statically
     
*
             
linked with the VM,
  
or the library cannot be mapped to a
     
*
             
native library image by the host system.
     
* @exception
  
NullPointerException if <code>libname</code> is
     
*
             
<code>null</code>
     
* @see
        
java.lang.Runtime#loadLibrary(java.lang.String)
     
* @see
        
java.lang.SecurityManager#checkLink(java.lang.String)
     
*/

    
@CallerSensitive
    
public static void loadLibrary(String libname) {
        
Runtime.getRuntime().loadLibrary0(Reflection.getCallerClass(), libname);
    
}

    
/**
     
* Maps a library name into a platform-specific string representing
     
* a native library.
     
*
     
* @param
      
libname the name of the library.
     
* @returna platform-dependent native library name.
     
* @exception
  
NullPointerException if <code>libname</code> is
     
*
             
<code>null</code>
     
* @see
        
java.lang.System#loadLibrary(java.lang.String)
     
* @see
        
java.lang.ClassLoader#findLibrary(java.lang.String)
     
* @since
      
1.2
     
*/

    
public static native String mapLibraryName(String libname);

    
/**
     
* Create PrintStream for stdout/err based on encoding.
     
*/

    
private static PrintStream newPrintStream(FileOutputStream fos, String enc) {
       
if (enc != null) {
            
try {
                
return new PrintStream(new BufferedOutputStream(fos, 128), true, enc);
            
} catch (UnsupportedEncodingException uee) {}
        
}
        
return new PrintStream(new BufferedOutputStream(fos, 128), true);
    
}


    
/**
     
* Initialize the system class.
  
Called after thread initialization.
     
*/

    
private static void initializeSystemClass() {

        
// VM might invoke JNU_NewStringPlatform() to set those encoding
        
// sensitive properties (user.home, user.name, boot.class.path, etc.)
        
// during "props" initialization, in which it may need access, via
        
// System.getProperty(), to the related system encoding property that
        
// have been initialized (put into "props") at early stage of the
        
// initialization. So make sure the "props" is available at the
        
// very beginning of the initialization and all system properties to
        
// be put into it directly.
        
props = new Properties();
        
initProperties(props);
  
// initialized by the VM

        
// There are certain system configurations that may be controlled by
        
// VM options such as the maximum amount of direct memory and
        
// Integer cache size used to support the object identity semantics
        
// of autoboxing.
  
Typically, the library will obtain these values

        
// from the properties set by the VM.
  
If the properties are for
        
// internal implementation use only, these properties should be
        
// removed from the system properties.
        
//
        
// See java.lang.Integer.IntegerCache and the
        
// sun.misc.VM.saveAndRemoveProperties method for example.
        
//
        
// Save a private copy of the system properties object that
        
// can only be accessed by the internal implementation.
  
Remove
        
// certain system properties that are not intended for public access.
        
sun.misc.VM.saveAndRemoveProperties(props);


        
lineSeparator = props.getProperty("line.separator");
        
sun.misc.Version.init();

        
FileInputStream fdIn = new FileInputStream(FileDescriptor.in);
        
FileOutputStream fdOut = new FileOutputStream(FileDescriptor.out);
        
FileOutputStream fdErr = new FileOutputStream(FileDescriptor.err);
        
setIn0(new BufferedInputStream(fdIn));
        
setOut0(newPrintStream(fdOut, props.getProperty("sun.stdout.encoding")));
        
setErr0(newPrintStream(fdErr, props.getProperty("sun.stderr.encoding")));

        
// Load the zip library now in order to keep java.util.zip.ZipFile
        
// from trying to use itself to load this library later.
        
loadLibrary("zip");

        
// Setup Java signal handlers for HUP, TERM, and INT (where available).
        
Terminator.setup();

        
// Initialize any miscellenous operating system settings that need to be
        
// set for the class libraries. Currently this is no-op everywhere except
        
// for Windows where the process-wide error mode is set before the java.io
        
// classes are used.
        
sun.misc.VM.initializeOSEnvironment();

        
// The main thread is not added to its thread group in the same
        
// way as other threads; we must do it ourselves here.
        
Thread current = Thread.currentThread();
        
current.getThreadGroup().add(current);

        
// register shared secrets
        
setJavaLangAccess();

        
// Subsystems that are invoked during initialization can invoke
        
// sun.misc.VM.isBooted() in order to avoid doing things that should
        
// wait until the application class loader has been set up.
        
// IMPORTANT: Ensure that this remains the last initialization action!
        
sun.misc.VM.booted();
    
}

    
private static void setJavaLangAccess() {
        
// Allow privileged classes outside of java.lang
        
sun.misc.SharedSecrets.setJavaLangAccess(new sun.misc.JavaLangAccess(){
            
public sun.reflect.ConstantPool getConstantPool(Class<?> klass) {
                
return klass.getConstantPool();
            
}
            
public boolean casAnnotationType(Class<?> klass, AnnotationType oldType, AnnotationType newType) {
                
return klass.casAnnotationType(oldType, newType);
            
}
            
public AnnotationType getAnnotationType(Class<?> klass) {
                
return klass.getAnnotationType();
            
}
            
public Map<Class<? extends Annotation>, Annotation> getDeclaredAnnotationMap(Class<?> klass) {
                
return klass.getDeclaredAnnotationMap();
            
}
            
public byte[] getRawClassAnnotations(Class<?> klass) {
                
return klass.getRawAnnotations();
            
}
            
public byte[] getRawClassTypeAnnotations(Class<?> klass) {
                
return klass.getRawTypeAnnotations();
            
}
            
public byte[] getRawExecutableTypeAnnotations(Executable executable) {
                
return Class.getExecutableTypeAnnotationBytes(executable);
            
}
            
public <E extends Enum<E>>
                    
E[] getEnumConstantsShared(Class<E> klass) {
                
return klass.getEnumConstantsShared();
            
}
            
public void blockedOn(Thread t, Interruptible b) {
                
t.blockedOn(b);
            
}
            
public void registerShutdownHook(int slot, boolean registerShutdownInProgress, Runnable hook) {
                
Shutdown.add(slot, registerShutdownInProgress, hook);
            
}
            
public int getStackTraceDepth(Throwable t) {
                
return t.getStackTraceDepth();
            
}
            
public StackTraceElement getStackTraceElement(Throwable t, int i) {
                
return t.getStackTraceElement(i);
            
}
            
public String newStringUnsafe(char[] chars) {
                
return new String(chars, true);
            
}
            
public Thread newThreadWithAcc(Runnable target, AccessControlContext acc) {
                
return new Thread(target, acc);
            
}
            
public void invokeFinalize(Object o) throws Throwable {
                
o.finalize();
            
}
        
});
    
}
}