564 lines
21 KiB
Java
564 lines
21 KiB
Java
/* System.java -- useful methods to interface with the system
|
|
Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
|
|
|
|
This file is part of GNU Classpath.
|
|
|
|
GNU Classpath is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2, or (at your option)
|
|
any later version.
|
|
|
|
GNU Classpath 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 for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with GNU Classpath; see the file COPYING. If not, write to the
|
|
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
|
02111-1307 USA.
|
|
|
|
Linking this library statically or dynamically with other modules is
|
|
making a combined work based on this library. Thus, the terms and
|
|
conditions of the GNU General Public License cover the whole
|
|
combination.
|
|
|
|
As a special exception, the copyright holders of this library give you
|
|
permission to link this library with independent modules to produce an
|
|
executable, regardless of the license terms of these independent
|
|
modules, and to copy and distribute the resulting executable under
|
|
terms of your choice, provided that you also meet, for each linked
|
|
independent module, the terms and conditions of the license of that
|
|
module. An independent module is a module which is not derived from
|
|
or based on this library. If you modify this library, you may extend
|
|
this exception to your version of the library, but you are not
|
|
obligated to do so. If you do not wish to do so, delete this
|
|
exception statement from your version. */
|
|
|
|
|
|
package java.lang;
|
|
|
|
import java.io.*;
|
|
import java.util.Properties;
|
|
import java.util.PropertyPermission;
|
|
import gnu.classpath.Configuration;
|
|
|
|
/**
|
|
* System represents system-wide resources; things that represent the
|
|
* general environment. As such, all methods are static.
|
|
*
|
|
* @author John Keiser
|
|
* @author Eric Blake <ebb9@email.byu.edu>
|
|
* @since 1.0
|
|
* @status still missing 1.4 functionality
|
|
*/
|
|
public final class System
|
|
{
|
|
// WARNING: System is a CORE class in the bootstrap cycle. See the comments
|
|
// in vm/reference/java/lang/Runtime for implications of this fact.
|
|
|
|
/**
|
|
* Add to the default properties. The field is stored in Runtime, because
|
|
* of the bootstrap sequence; but this adds several useful properties to
|
|
* the defaults. Once the default is stabilized, it should not be modified;
|
|
* instead it is passed as a parent properties for fast setup of the
|
|
* defaults when calling <code>setProperties(null)</code>.
|
|
*/
|
|
static
|
|
{
|
|
// Note that this loadLibrary() takes precedence over the one in Object,
|
|
// since Object.<clinit> is waiting for System.<clinit> to complete
|
|
// first; but loading a library twice is harmless.
|
|
if (Configuration.INIT_LOAD_LIBRARY)
|
|
loadLibrary("javalang");
|
|
|
|
Properties defaultProperties = Runtime.defaultProperties;
|
|
defaultProperties.put("gnu.cpu.endian",
|
|
isWordsBigEndian() ? "big" : "little");
|
|
|
|
// XXX FIXME - Temp hack for old systems that set the wrong property
|
|
if (defaultProperties.get("java.io.tmpdir") == null)
|
|
defaultProperties.put("java.io.tmpdir",
|
|
defaultProperties.get("java.tmpdir"));
|
|
}
|
|
|
|
/**
|
|
* Stores the current system properties. This can be modified by
|
|
* {@link #setProperties(Properties)}, but will never be null, because
|
|
* setProperties(null) sucks in the default properties.
|
|
*/
|
|
private static Properties properties
|
|
= new Properties(Runtime.defaultProperties);
|
|
|
|
/**
|
|
* The standard InputStream. This is assigned at startup and starts its
|
|
* life perfectly valid. Although it is marked final, you can change it
|
|
* using {@link #setIn(InputStream)} through some hefty VM magic.
|
|
*
|
|
* <p>This corresponds to the C stdin and C++ cin variables, which
|
|
* typically input from the keyboard, but may be used to pipe input from
|
|
* other processes or files. That should all be transparent to you,
|
|
* however.
|
|
*/
|
|
public static final InputStream in
|
|
= new BufferedInputStream (new FileInputStream(FileDescriptor.in));
|
|
/**
|
|
* The standard output PrintStream. This is assigned at startup and
|
|
* starts its life perfectly valid. Although it is marked final, you can
|
|
* change it using {@link #setOut(PrintStream)} through some hefty VM magic.
|
|
*
|
|
* <p>This corresponds to the C stdout and C++ cout variables, which
|
|
* typically output normal messages to the screen, but may be used to pipe
|
|
* output to other processes or files. That should all be transparent to
|
|
* you, however.
|
|
*/
|
|
public static final PrintStream out
|
|
= new PrintStream(new BufferedOutputStream (new FileOutputStream(FileDescriptor.out)), true);
|
|
/**
|
|
* The standard output PrintStream. This is assigned at startup and
|
|
* starts its life perfectly valid. Although it is marked final, you can
|
|
* change it using {@link #setOut(PrintStream)} through some hefty VM magic.
|
|
*
|
|
* <p>This corresponds to the C stderr and C++ cerr variables, which
|
|
* typically output error messages to the screen, but may be used to pipe
|
|
* output to other processes or files. That should all be transparent to
|
|
* you, however.
|
|
*/
|
|
public static final PrintStream err
|
|
= new PrintStream(new BufferedOutputStream (new FileOutputStream(FileDescriptor.err)), true);
|
|
|
|
/**
|
|
* This class is uninstantiable.
|
|
*/
|
|
private System()
|
|
{
|
|
}
|
|
|
|
/**
|
|
* Set {@link #in} to a new InputStream. This uses some VM magic to change
|
|
* a "final" variable, so naturally there is a security check,
|
|
* <code>RuntimePermission("setIO")</code>.
|
|
*
|
|
* @param in the new InputStream
|
|
* @throws SecurityException if permission is denied
|
|
* @since 1.1
|
|
*/
|
|
public static void setIn(InputStream in)
|
|
{
|
|
SecurityManager sm = Runtime.securityManager; // Be thread-safe.
|
|
if (sm != null)
|
|
sm.checkPermission(new RuntimePermission("setIO"));
|
|
setIn0(in);
|
|
}
|
|
|
|
/**
|
|
* Set {@link #out} to a new PrintStream. This uses some VM magic to change
|
|
* a "final" variable, so naturally there is a security check,
|
|
* <code>RuntimePermission("setIO")</code>.
|
|
*
|
|
* @param out the new PrintStream
|
|
* @throws SecurityException if permission is denied
|
|
* @since 1.1
|
|
*/
|
|
public static void setOut(PrintStream out)
|
|
{
|
|
SecurityManager sm = Runtime.securityManager; // Be thread-safe.
|
|
if (sm != null)
|
|
sm.checkPermission(new RuntimePermission("setIO"));
|
|
setOut0(out);
|
|
}
|
|
|
|
/**
|
|
* Set {@link #err} to a new PrintStream. This uses some VM magic to change
|
|
* a "final" variable, so naturally there is a security check,
|
|
* <code>RuntimePermission("setIO")</code>.
|
|
*
|
|
* @param err the new PrintStream
|
|
* @throws SecurityException if permission is denied
|
|
* @since 1.1
|
|
*/
|
|
public static void setErr(PrintStream err)
|
|
{
|
|
SecurityManager sm = Runtime.securityManager; // Be thread-safe.
|
|
if (sm != null)
|
|
sm.checkPermission(new RuntimePermission("setIO"));
|
|
setErr0(err);
|
|
}
|
|
|
|
/**
|
|
* Set the current SecurityManager. If a security manager already exists,
|
|
* then <code>RuntimePermission("setSecurityManager")</code> is checked
|
|
* first. Since this permission is denied by the default security manager,
|
|
* setting the security manager is often an irreversible action.
|
|
*
|
|
* <STRONG>Spec Note:</STRONG> Don't ask me, I didn't write it. It looks
|
|
* pretty vulnerable; whoever gets to the gate first gets to set the policy.
|
|
* There is probably some way to set the original security manager as a
|
|
* command line argument to the VM, but I don't know it.
|
|
*
|
|
* @param sm the new SecurityManager
|
|
* @throws SecurityException if permission is denied
|
|
*/
|
|
public synchronized static void setSecurityManager(SecurityManager sm)
|
|
{
|
|
// Implementation note: the field lives in Runtime because of bootstrap
|
|
// initialization issues. This method is synchronized so that no other
|
|
// thread changes it to null before this thread makes the change.
|
|
if (Runtime.securityManager != null)
|
|
Runtime.securityManager.checkPermission
|
|
(new RuntimePermission("setSecurityManager"));
|
|
Runtime.securityManager = sm;
|
|
}
|
|
|
|
/**
|
|
* Get the current SecurityManager. If the SecurityManager has not been
|
|
* set yet, then this method returns null.
|
|
*
|
|
* @return the current SecurityManager, or null
|
|
*/
|
|
public static SecurityManager getSecurityManager()
|
|
{
|
|
// Implementation note: the field lives in Runtime because of bootstrap
|
|
// initialization issues.
|
|
return Runtime.securityManager;
|
|
}
|
|
|
|
/**
|
|
* Get the current time, measured in the number of milliseconds from the
|
|
* beginning of Jan. 1, 1970. This is gathered from the system clock, with
|
|
* any attendant incorrectness (it may be timezone dependent).
|
|
*
|
|
* @return the current time
|
|
* @see java.util.Date
|
|
*/
|
|
public static native long currentTimeMillis();
|
|
|
|
/**
|
|
* Copy one array onto another from <code>src[srcStart]</code> ...
|
|
* <code>src[srcStart+len-1]</code> to <code>dest[destStart]</code> ...
|
|
* <code>dest[destStart+len-1]</code>. First, the arguments are validated:
|
|
* neither array may be null, they must be of compatible types, and the
|
|
* start and length must fit within both arrays. Then the copying starts,
|
|
* and proceeds through increasing slots. If src and dest are the same
|
|
* array, this will appear to copy the data to a temporary location first.
|
|
* An ArrayStoreException in the middle of copying will leave earlier
|
|
* elements copied, but later elements unchanged.
|
|
*
|
|
* @param src the array to copy elements from
|
|
* @param srcStart the starting position in src
|
|
* @param dest the array to copy elements to
|
|
* @param destStart the starting position in dest
|
|
* @param len the number of elements to copy
|
|
* @throws NullPointerException if src or dest is null
|
|
* @throws ArrayStoreException if src or dest is not an array, if they are
|
|
* not compatible array types, or if an incompatible runtime type
|
|
* is stored in dest
|
|
* @throws IndexOutOfBoundsException if len is negative, or if the start or
|
|
* end copy position in either array is out of bounds
|
|
*/
|
|
public static native void arraycopy(Object src, int srcStart,
|
|
Object dest, int destStart, int len);
|
|
|
|
/**
|
|
* Get a hash code computed by the VM for the Object. This hash code will
|
|
* be the same as Object's hashCode() method. It is usually some
|
|
* convolution of the pointer to the Object internal to the VM. It
|
|
* follows standard hash code rules, in that it will remain the same for a
|
|
* given Object for the lifetime of that Object.
|
|
*
|
|
* @param o the Object to get the hash code for
|
|
* @return the VM-dependent hash code for this Object
|
|
* @since 1.1
|
|
*/
|
|
public static native int identityHashCode(Object o);
|
|
|
|
/**
|
|
* Get all the system properties at once. A security check may be performed,
|
|
* <code>checkPropertiesAccess</code>. Note that a security manager may
|
|
* allow getting a single property, but not the entire group.
|
|
*
|
|
* <p>The required properties include:
|
|
* <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.vm.specification.version <dd>VM Spec version
|
|
* <dt>java.vm.specification.vendor <dd>VM Spec vendor
|
|
* <dt>java.vm.specification.name <dd>VM Spec name
|
|
* <dt>java.vm.version <dd>VM implementation version
|
|
* <dt>java.vm.vendor <dd>VM implementation vendor
|
|
* <dt>java.vm.name <dd>VM implementation name
|
|
* <dt>java.specification.version <dd>Java Runtime Environment version
|
|
* <dt>java.specification.vendor <dd>Java Runtime Environment vendor
|
|
* <dt>java.specification.name <dd>Java Runtime Environment name
|
|
* <dt>java.class.version <dd>Java class version number
|
|
* <dt>java.class.path <dd>Java classpath
|
|
* <dt>java.library.path <dd>Path for finding Java libraries
|
|
* <dt>java.io.tmpdir <dd>Default temp file path
|
|
* <dt>java.compiler <dd>Name of JIT to use
|
|
* <dt>java.ext.dirs <dd>Java extension path
|
|
* <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>
|
|
*
|
|
* In addition, gnu defines several other properties, where ? stands for
|
|
* each character in '0' through '9':
|
|
* <dl>
|
|
* <dt> gnu.cpu.endian <dd>big or little
|
|
* <dt> gnu.java.io.encoding_scheme_alias.ISO-8859-? <dd>8859_?
|
|
* <dt> gnu.java.io.encoding_scheme_alias.iso-8859-? <dd>8859_?
|
|
* <dt> gnu.java.io.encoding_scheme_alias.iso8859_? <dd>8859_?
|
|
* <dt> gnu.java.io.encoding_scheme_alias.iso-latin-_? <dd>8859_?
|
|
* <dt> gnu.java.io.encoding_scheme_alias.latin? <dd>8859_?
|
|
* <dt> gnu.java.io.encoding_scheme_alias.UTF-8 <dd>UTF8
|
|
* <dt> gnu.java.io.encoding_scheme_alias.utf-8 <dd>UTF8
|
|
* </dl>
|
|
*
|
|
* @return the system properties, will never be null
|
|
* @throws SecurityException if permission is denied
|
|
*/
|
|
public static Properties getProperties()
|
|
{
|
|
SecurityManager sm = Runtime.securityManager; // Be thread-safe.
|
|
if (sm != null)
|
|
sm.checkPropertiesAccess();
|
|
return properties;
|
|
}
|
|
|
|
/**
|
|
* Set all the system properties at once. A security check may be performed,
|
|
* <code>checkPropertiesAccess</code>. Note that a security manager may
|
|
* allow setting a single property, but not the entire group. An argument
|
|
* of null resets the properties to the startup default.
|
|
*
|
|
* @param properties the new set of system properties
|
|
* @throws SecurityException if permission is denied
|
|
*/
|
|
public static void setProperties(Properties properties)
|
|
{
|
|
SecurityManager sm = Runtime.securityManager; // Be thread-safe.
|
|
if (sm != null)
|
|
sm.checkPropertiesAccess();
|
|
if (properties == null)
|
|
properties = new Properties(Runtime.defaultProperties);
|
|
System.properties = properties;
|
|
}
|
|
|
|
/**
|
|
* Get a single system property by name. A security check may be performed,
|
|
* <code>checkPropertyAccess(key)</code>.
|
|
*
|
|
* @param key the name of the system property to get
|
|
* @return the property, or null if not found
|
|
* @throws SecurityException if permission is denied
|
|
* @throws NullPointerException if key is null
|
|
* @throws IllegalArgumentException if key is ""
|
|
*/
|
|
public static String getProperty(String key)
|
|
{
|
|
SecurityManager sm = Runtime.securityManager; // Be thread-safe.
|
|
if (sm != null)
|
|
sm.checkPropertyAccess(key);
|
|
else if (key.length() == 0)
|
|
throw new IllegalArgumentException("key can't be empty");
|
|
return properties.getProperty(key);
|
|
}
|
|
|
|
/**
|
|
* Get a single system property by name. A security check may be performed,
|
|
* <code>checkPropertyAccess(key)</code>.
|
|
*
|
|
* @param key the name of the system property to get
|
|
* @param def the default
|
|
* @return the property, or def if not found
|
|
* @throws SecurityException if permission is denied
|
|
* @throws NullPointerException if key is null
|
|
* @throws IllegalArgumentException if key is ""
|
|
*/
|
|
public static String getProperty(String key, String def)
|
|
{
|
|
SecurityManager sm = Runtime.securityManager; // Be thread-safe.
|
|
if (sm != null)
|
|
sm.checkPropertyAccess(key);
|
|
return properties.getProperty(key, def);
|
|
}
|
|
|
|
/**
|
|
* Set a single system property by name. A security check may be performed,
|
|
* <code>checkPropertyAccess(key, "write")</code>.
|
|
*
|
|
* @param key the name of the system property to set
|
|
* @param value the new value
|
|
* @return the previous value, or null
|
|
* @throws SecurityException if permission is denied
|
|
* @throws NullPointerException if key is null
|
|
* @throws IllegalArgumentException if key is ""
|
|
* @since 1.2
|
|
*/
|
|
public static String setProperty(String key, String value)
|
|
{
|
|
SecurityManager sm = Runtime.securityManager; // Be thread-safe.
|
|
if (sm != null)
|
|
sm.checkPermission(new PropertyPermission(key, "write"));
|
|
return (String) properties.setProperty(key, value);
|
|
}
|
|
|
|
/**
|
|
* This used to get an environment variable, but following Sun's lead,
|
|
* it now throws an Error. Use <code>getProperty</code> instead.
|
|
*
|
|
* @param name the name of the environment variable
|
|
* @return this does not return
|
|
* @throws Error this is not supported
|
|
* @deprecated use {@link #getProperty(String)}; getenv is not supported
|
|
*/
|
|
public static String getenv(String name)
|
|
{
|
|
throw new Error("getenv no longer supported, use properties instead: "
|
|
+ name);
|
|
}
|
|
|
|
/**
|
|
* Terminate the Virtual Machine. This just calls
|
|
* <code>Runtime.getRuntime().exit(status)</code>, and never returns.
|
|
* Obviously, a security check is in order, <code>checkExit</code>.
|
|
*
|
|
* @param status the exit status; by convention non-zero is abnormal
|
|
* @throws SecurityException if permission is denied
|
|
* @see Runtime#exit(int)
|
|
*/
|
|
public static void exit(int status)
|
|
{
|
|
Runtime.getRuntime().exit(status);
|
|
}
|
|
|
|
/**
|
|
* Calls the garbage collector. This is only a hint, and it is up to the
|
|
* implementation what this hint suggests, but it usually causes a
|
|
* best-effort attempt to reclaim unused memory from discarded objects.
|
|
* This calls <code>Runtime.getRuntime().gc()</code>.
|
|
*
|
|
* @see Runtime#gc()
|
|
*/
|
|
public static void gc()
|
|
{
|
|
Runtime.getRuntime().gc();
|
|
}
|
|
|
|
/**
|
|
* Runs object finalization on pending objects. This is only a hint, and
|
|
* it is up to the implementation what this hint suggests, but it usually
|
|
* causes a best-effort attempt to run finalizers on all objects ready
|
|
* to be reclaimed. This calls
|
|
* <code>Runtime.getRuntime().runFinalization()</code>.
|
|
*
|
|
* @see Runtime#runFinalization()
|
|
*/
|
|
public static void runFinalization()
|
|
{
|
|
Runtime.getRuntime().runFinalization();
|
|
}
|
|
|
|
/**
|
|
* Tell the Runtime whether to run finalization before exiting the
|
|
* JVM. This is inherently unsafe in multi-threaded applications,
|
|
* since it can force initialization on objects which are still in use
|
|
* by live threads, leading to deadlock; therefore this is disabled by
|
|
* default. There may be a security check, <code>checkExit(0)</code>. This
|
|
* calls <code>Runtime.getRuntime().runFinalizersOnExit()</code>.
|
|
*
|
|
* @param finalizeOnExit whether to run finalizers on exit
|
|
* @throws SecurityException if permission is denied
|
|
* @see Runtime#runFinalizersOnExit()
|
|
* @since 1.1
|
|
* @deprecated never rely on finalizers to do a clean, thread-safe,
|
|
* mop-up from your code
|
|
*/
|
|
public static void runFinalizersOnExit(boolean finalizeOnExit)
|
|
{
|
|
Runtime.getRuntime().runFinalizersOnExit(finalizeOnExit);
|
|
}
|
|
|
|
/**
|
|
* 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>.
|
|
*
|
|
* @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>.
|
|
*
|
|
* @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);
|
|
}
|
|
|
|
/**
|
|
* Detect big-endian systems.
|
|
*
|
|
* @return true if the system is big-endian.
|
|
*/
|
|
static native boolean isWordsBigEndian();
|
|
|
|
/**
|
|
* 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);
|
|
} // class System
|