557 lines
21 KiB
Java
557 lines
21 KiB
Java
/* System.java -- useful methods to interface with the system
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Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
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Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.lang;
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import gnu.classpath.SystemProperties;
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import java.io.BufferedInputStream;
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import java.io.BufferedOutputStream;
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import java.io.FileDescriptor;
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import java.io.FileInputStream;
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import java.io.FileOutputStream;
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import java.io.InputStream;
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import java.io.PrintStream;
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import java.util.Properties;
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import java.util.PropertyPermission;
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/**
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* System represents system-wide resources; things that represent the
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* general environment. As such, all methods are static.
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*
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* @author John Keiser
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* @author Eric Blake (ebb9@email.byu.edu)
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* @since 1.0
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* @status still missing 1.4 functionality
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*/
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public final class System
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{
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// WARNING: System is a CORE class in the bootstrap cycle. See the comments
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// in vm/reference/java/lang/Runtime for implications of this fact.
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/**
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* The standard InputStream. This is assigned at startup and starts its
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* life perfectly valid. Although it is marked final, you can change it
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* using {@link #setIn(InputStream)} through some hefty VM magic.
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*
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* <p>This corresponds to the C stdin and C++ cin variables, which
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* typically input from the keyboard, but may be used to pipe input from
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* other processes or files. That should all be transparent to you,
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* however.
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*/
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public static final InputStream in
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= new BufferedInputStream(new FileInputStream(FileDescriptor.in));
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/**
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* The standard output PrintStream. This is assigned at startup and
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* starts its life perfectly valid. Although it is marked final, you can
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* change it using {@link #setOut(PrintStream)} through some hefty VM magic.
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*
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* <p>This corresponds to the C stdout and C++ cout variables, which
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* typically output normal messages to the screen, but may be used to pipe
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* output to other processes or files. That should all be transparent to
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* you, however.
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*/
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public static final PrintStream out
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= new PrintStream(new BufferedOutputStream(new FileOutputStream(FileDescriptor.out)), true);
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/**
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* The standard output PrintStream. This is assigned at startup and
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* starts its life perfectly valid. Although it is marked final, you can
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* change it using {@link #setErr(PrintStream)} through some hefty VM magic.
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*
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* <p>This corresponds to the C stderr and C++ cerr variables, which
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* typically output error messages to the screen, but may be used to pipe
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* output to other processes or files. That should all be transparent to
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* you, however.
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*/
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public static final PrintStream err
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= new PrintStream(new BufferedOutputStream(new FileOutputStream(FileDescriptor.err)), true);
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/**
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* This class is uninstantiable.
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*/
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private System()
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{
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}
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/**
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* Set {@link #in} to a new InputStream. This uses some VM magic to change
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* a "final" variable, so naturally there is a security check,
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* <code>RuntimePermission("setIO")</code>.
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*
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* @param in the new InputStream
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* @throws SecurityException if permission is denied
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* @since 1.1
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*/
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public static void setIn(InputStream in)
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{
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SecurityManager sm = SecurityManager.current; // Be thread-safe.
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if (sm != null)
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sm.checkPermission(new RuntimePermission("setIO"));
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setIn0(in);
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}
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/**
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* Set {@link #out} to a new PrintStream. This uses some VM magic to change
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* a "final" variable, so naturally there is a security check,
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* <code>RuntimePermission("setIO")</code>.
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*
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* @param out the new PrintStream
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* @throws SecurityException if permission is denied
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* @since 1.1
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*/
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public static void setOut(PrintStream out)
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{
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SecurityManager sm = SecurityManager.current; // Be thread-safe.
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if (sm != null)
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sm.checkPermission(new RuntimePermission("setIO"));
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setOut0(out);
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}
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/**
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* Set {@link #err} to a new PrintStream. This uses some VM magic to change
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* a "final" variable, so naturally there is a security check,
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* <code>RuntimePermission("setIO")</code>.
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*
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* @param err the new PrintStream
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* @throws SecurityException if permission is denied
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* @since 1.1
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*/
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public static void setErr(PrintStream err)
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{
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SecurityManager sm = SecurityManager.current; // Be thread-safe.
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if (sm != null)
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sm.checkPermission(new RuntimePermission("setIO"));
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setErr0(err);
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}
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/**
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* Set the current SecurityManager. If a security manager already exists,
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* then <code>RuntimePermission("setSecurityManager")</code> is checked
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* first. Since this permission is denied by the default security manager,
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* setting the security manager is often an irreversible action.
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*
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* <STRONG>Spec Note:</STRONG> Don't ask me, I didn't write it. It looks
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* pretty vulnerable; whoever gets to the gate first gets to set the policy.
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* There is probably some way to set the original security manager as a
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* command line argument to the VM, but I don't know it.
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*
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* @param sm the new SecurityManager
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* @throws SecurityException if permission is denied
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*/
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public static synchronized void setSecurityManager(SecurityManager sm)
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{
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// Implementation note: the field lives in SecurityManager because of
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// bootstrap initialization issues. This method is synchronized so that
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// no other thread changes it to null before this thread makes the change.
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if (SecurityManager.current != null)
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SecurityManager.current.checkPermission
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(new RuntimePermission("setSecurityManager"));
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SecurityManager.current = sm;
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}
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/**
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* Get the current SecurityManager. If the SecurityManager has not been
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* set yet, then this method returns null.
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*
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* @return the current SecurityManager, or null
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*/
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public static SecurityManager getSecurityManager()
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{
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return SecurityManager.current;
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}
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/**
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* Get the current time, measured in the number of milliseconds from the
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* beginning of Jan. 1, 1970. This is gathered from the system clock, with
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* any attendant incorrectness (it may be timezone dependent).
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*
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* @return the current time
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* @see java.util.Date
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*/
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public static native long currentTimeMillis();
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/**
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* Copy one array onto another from <code>src[srcStart]</code> ...
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* <code>src[srcStart+len-1]</code> to <code>dest[destStart]</code> ...
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* <code>dest[destStart+len-1]</code>. First, the arguments are validated:
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* neither array may be null, they must be of compatible types, and the
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* start and length must fit within both arrays. Then the copying starts,
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* and proceeds through increasing slots. If src and dest are the same
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* array, this will appear to copy the data to a temporary location first.
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* An ArrayStoreException in the middle of copying will leave earlier
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* elements copied, but later elements unchanged.
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*
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* @param src the array to copy elements from
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* @param srcStart the starting position in src
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* @param dest the array to copy elements to
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* @param destStart the starting position in dest
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* @param len the number of elements to copy
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* @throws NullPointerException if src or dest is null
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* @throws ArrayStoreException if src or dest is not an array, if they are
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* not compatible array types, or if an incompatible runtime type
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* is stored in dest
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* @throws IndexOutOfBoundsException if len is negative, or if the start or
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* end copy position in either array is out of bounds
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*/
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public static native void arraycopy(Object src, int srcStart,
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Object dest, int destStart, int len);
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/**
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* Get a hash code computed by the VM for the Object. This hash code will
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* be the same as Object's hashCode() method. It is usually some
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* convolution of the pointer to the Object internal to the VM. It
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* follows standard hash code rules, in that it will remain the same for a
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* given Object for the lifetime of that Object.
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*
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* @param o the Object to get the hash code for
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* @return the VM-dependent hash code for this Object
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* @since 1.1
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*/
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public static native int identityHashCode(Object o);
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/**
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* Get all the system properties at once. A security check may be performed,
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* <code>checkPropertiesAccess</code>. Note that a security manager may
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* allow getting a single property, but not the entire group.
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*
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* <p>The required properties include:
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* <dl>
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* <dt>java.version</dt> <dd>Java version number</dd>
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* <dt>java.vendor</dt> <dd>Java vendor specific string</dd>
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* <dt>java.vendor.url</dt> <dd>Java vendor URL</dd>
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* <dt>java.home</dt> <dd>Java installation directory</dd>
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* <dt>java.vm.specification.version</dt> <dd>VM Spec version</dd>
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* <dt>java.vm.specification.vendor</dt> <dd>VM Spec vendor</dd>
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* <dt>java.vm.specification.name</dt> <dd>VM Spec name</dd>
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* <dt>java.vm.version</dt> <dd>VM implementation version</dd>
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* <dt>java.vm.vendor</dt> <dd>VM implementation vendor</dd>
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* <dt>java.vm.name</dt> <dd>VM implementation name</dd>
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* <dt>java.specification.version</dt> <dd>Java Runtime Environment version</dd>
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* <dt>java.specification.vendor</dt> <dd>Java Runtime Environment vendor</dd>
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* <dt>java.specification.name</dt> <dd>Java Runtime Environment name</dd>
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* <dt>java.class.version</dt> <dd>Java class version number</dd>
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* <dt>java.class.path</dt> <dd>Java classpath</dd>
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* <dt>java.library.path</dt> <dd>Path for finding Java libraries</dd>
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* <dt>java.io.tmpdir</dt> <dd>Default temp file path</dd>
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* <dt>java.compiler</dt> <dd>Name of JIT to use</dd>
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* <dt>java.ext.dirs</dt> <dd>Java extension path</dd>
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* <dt>os.name</dt> <dd>Operating System Name</dd>
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* <dt>os.arch</dt> <dd>Operating System Architecture</dd>
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* <dt>os.version</dt> <dd>Operating System Version</dd>
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* <dt>file.separator</dt> <dd>File separator ("/" on Unix)</dd>
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* <dt>path.separator</dt> <dd>Path separator (":" on Unix)</dd>
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* <dt>line.separator</dt> <dd>Line separator ("\n" on Unix)</dd>
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* <dt>user.name</dt> <dd>User account name</dd>
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* <dt>user.home</dt> <dd>User home directory</dd>
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* <dt>user.dir</dt> <dd>User's current working directory</dd>
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* </dl>
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*
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* In addition, gnu defines several other properties, where ? stands for
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* each character in '0' through '9':
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* <dl>
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* <dt>gnu.classpath.home</dt> <dd>Path to the classpath libraries.</dd>
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* <dt>gnu.classpath.version</dt> <dd>Version of the classpath libraries.</dd>
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* <dt>gnu.classpath.vm.shortname</dt> <dd>Succinct version of the VM name;
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* used for finding property files in file system</dd>
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* <dt>gnu.classpath.home.url</dt> <dd> Base URL; used for finding
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* property files in file system</dd>
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* <dt>gnu.cpu.endian</dt> <dd>big or little</dd>
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* <dt>gnu.java.io.encoding_scheme_alias.ISO-8859-?</dt> <dd>8859_?</dd>
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* <dt>gnu.java.io.encoding_scheme_alias.iso-8859-?</dt> <dd>8859_?</dd>
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* <dt>gnu.java.io.encoding_scheme_alias.iso8859_?</dt> <dd>8859_?</dd>
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* <dt>gnu.java.io.encoding_scheme_alias.iso-latin-_?</dt> <dd>8859_?</dd>
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* <dt>gnu.java.io.encoding_scheme_alias.latin?</dt> <dd>8859_?</dd>
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* <dt>gnu.java.io.encoding_scheme_alias.UTF-8</dt> <dd>UTF8</dd>
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* <dt>gnu.java.io.encoding_scheme_alias.utf-8</dt> <dd>UTF8</dd>
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* </dl>
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*
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* @return the system properties, will never be null
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* @throws SecurityException if permission is denied
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*/
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public static Properties getProperties()
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{
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SecurityManager sm = SecurityManager.current; // Be thread-safe.
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if (sm != null)
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sm.checkPropertiesAccess();
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return SystemProperties.getProperties();
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}
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/**
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* Set all the system properties at once. A security check may be performed,
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* <code>checkPropertiesAccess</code>. Note that a security manager may
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* allow setting a single property, but not the entire group. An argument
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* of null resets the properties to the startup default.
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*
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* @param properties the new set of system properties
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* @throws SecurityException if permission is denied
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*/
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public static void setProperties(Properties properties)
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{
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SecurityManager sm = SecurityManager.current; // Be thread-safe.
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if (sm != null)
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sm.checkPropertiesAccess();
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SystemProperties.setProperties(properties);
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}
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/**
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* Get a single system property by name. A security check may be performed,
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* <code>checkPropertyAccess(key)</code>.
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*
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* @param key the name of the system property to get
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* @return the property, or null if not found
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* @throws SecurityException if permission is denied
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* @throws NullPointerException if key is null
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* @throws IllegalArgumentException if key is ""
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*/
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public static String getProperty(String key)
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{
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SecurityManager sm = SecurityManager.current; // Be thread-safe.
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if (sm != null)
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sm.checkPropertyAccess(key);
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else if (key.length() == 0)
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throw new IllegalArgumentException("key can't be empty");
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return SystemProperties.getProperty(key);
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}
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/**
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* Get a single system property by name. A security check may be performed,
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* <code>checkPropertyAccess(key)</code>.
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*
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* @param key the name of the system property to get
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* @param def the default
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* @return the property, or def if not found
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* @throws SecurityException if permission is denied
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* @throws NullPointerException if key is null
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* @throws IllegalArgumentException if key is ""
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*/
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public static String getProperty(String key, String def)
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{
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SecurityManager sm = SecurityManager.current; // Be thread-safe.
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if (sm != null)
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sm.checkPropertyAccess(key);
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return SystemProperties.getProperty(key, def);
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}
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/**
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* Set a single system property by name. A security check may be performed,
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* <code>checkPropertyAccess(key, "write")</code>.
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*
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* @param key the name of the system property to set
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* @param value the new value
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* @return the previous value, or null
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* @throws SecurityException if permission is denied
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* @throws NullPointerException if key is null
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* @throws IllegalArgumentException if key is ""
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* @since 1.2
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*/
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public static String setProperty(String key, String value)
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{
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SecurityManager sm = SecurityManager.current; // Be thread-safe.
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if (sm != null)
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sm.checkPermission(new PropertyPermission(key, "write"));
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return SystemProperties.setProperty(key, value);
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}
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/**
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* Gets the value of an environment variable.
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*
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* @param name the name of the environment variable
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* @return the string value of the variable or null when the
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* environment variable is not defined.
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* @throws NullPointerException
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* @throws SecurityException if permission is denied
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* @since 1.5
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* @specnote This method was deprecated in some JDK releases, but
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* was restored in 1.5.
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*/
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public static String getenv(String name)
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{
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if (name == null)
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throw new NullPointerException();
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SecurityManager sm = SecurityManager.current; // Be thread-safe.
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if (sm != null)
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sm.checkPermission(new RuntimePermission("getenv." + name));
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return getenv0(name);
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}
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/**
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* Terminate the Virtual Machine. This just calls
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* <code>Runtime.getRuntime().exit(status)</code>, and never returns.
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* Obviously, a security check is in order, <code>checkExit</code>.
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*
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* @param status the exit status; by convention non-zero is abnormal
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* @throws SecurityException if permission is denied
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* @see Runtime#exit(int)
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*/
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public static void exit(int status)
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{
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Runtime.getRuntime().exit(status);
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}
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/**
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* Calls the garbage collector. This is only a hint, and it is up to the
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* implementation what this hint suggests, but it usually causes a
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* best-effort attempt to reclaim unused memory from discarded objects.
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* This calls <code>Runtime.getRuntime().gc()</code>.
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*
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* @see Runtime#gc()
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*/
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public static void gc()
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{
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Runtime.getRuntime().gc();
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}
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/**
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* Runs object finalization on pending objects. This is only a hint, and
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* it is up to the implementation what this hint suggests, but it usually
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* causes a best-effort attempt to run finalizers on all objects ready
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* to be reclaimed. This calls
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* <code>Runtime.getRuntime().runFinalization()</code>.
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*
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* @see Runtime#runFinalization()
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*/
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public static void runFinalization()
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{
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Runtime.getRuntime().runFinalization();
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}
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/**
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* Tell the Runtime whether to run finalization before exiting the
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* JVM. This is inherently unsafe in multi-threaded applications,
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* since it can force initialization on objects which are still in use
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* by live threads, leading to deadlock; therefore this is disabled by
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* default. There may be a security check, <code>checkExit(0)</code>. This
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* calls <code>Runtime.getRuntime().runFinalizersOnExit()</code>.
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*
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* @param finalizeOnExit whether to run finalizers on exit
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* @throws SecurityException if permission is denied
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* @see Runtime#runFinalizersOnExit()
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* @since 1.1
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* @deprecated never rely on finalizers to do a clean, thread-safe,
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* mop-up from your code
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*/
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public static void runFinalizersOnExit(boolean finalizeOnExit)
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{
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Runtime.getRuntime().runFinalizersOnExit(finalizeOnExit);
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|
}
|
|
|
|
/**
|
|
* Load a code file using its explicit system-dependent filename. A security
|
|
* check may be performed, <code>checkLink</code>. This just calls
|
|
* <code>Runtime.getRuntime().load(filename)</code>.
|
|
*
|
|
* <p>
|
|
* The library is loaded using the class loader associated with the
|
|
* class associated with the invoking method.
|
|
*
|
|
* @param filename the code file to load
|
|
* @throws SecurityException if permission is denied
|
|
* @throws UnsatisfiedLinkError if the file cannot be loaded
|
|
* @see Runtime#load(String)
|
|
*/
|
|
public static void load(String filename)
|
|
{
|
|
Runtime.getRuntime().load(filename);
|
|
}
|
|
|
|
/**
|
|
* Load a library using its explicit system-dependent filename. A security
|
|
* check may be performed, <code>checkLink</code>. This just calls
|
|
* <code>Runtime.getRuntime().load(filename)</code>.
|
|
*
|
|
* <p>
|
|
* The library is loaded using the class loader associated with the
|
|
* class associated with the invoking method.
|
|
*
|
|
* @param libname the library file to load
|
|
* @throws SecurityException if permission is denied
|
|
* @throws UnsatisfiedLinkError if the file cannot be loaded
|
|
* @see Runtime#load(String)
|
|
*/
|
|
public static void loadLibrary(String libname)
|
|
{
|
|
Runtime.getRuntime().loadLibrary(libname);
|
|
}
|
|
|
|
/**
|
|
* Convert a library name to its platform-specific variant.
|
|
*
|
|
* @param libname the library name, as used in <code>loadLibrary</code>
|
|
* @return the platform-specific mangling of the name
|
|
* @since 1.2
|
|
*/
|
|
public static String mapLibraryName(String libname)
|
|
{
|
|
// XXX Fix this!!!!
|
|
return Runtime.nativeGetLibname("", libname);
|
|
}
|
|
|
|
/**
|
|
* Set {@link #in} to a new InputStream.
|
|
*
|
|
* @param in the new InputStream
|
|
* @see #setIn(InputStream)
|
|
*/
|
|
private static native void setIn0(InputStream in);
|
|
|
|
/**
|
|
* Set {@link #out} to a new PrintStream.
|
|
*
|
|
* @param out the new PrintStream
|
|
* @see #setOut(PrintStream)
|
|
*/
|
|
private static native void setOut0(PrintStream out);
|
|
|
|
/**
|
|
* Set {@link #err} to a new PrintStream.
|
|
*
|
|
* @param err the new PrintStream
|
|
* @see #setErr(PrintStream)
|
|
*/
|
|
private static native void setErr0(PrintStream err);
|
|
|
|
/**
|
|
* Gets the value of an environment variable.
|
|
*
|
|
* @see #getenv(String)
|
|
*/
|
|
static native String getenv0(String name);
|
|
} // class System
|