/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package java.lang;
import dalvik.system.VMRuntime;
import dalvik.system.VMStack;
import java.io.Console;
import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.nio.channels.Channel;
import java.nio.channels.spi.SelectorProvider;
import java.util.AbstractMap;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import libcore.icu.ICU;
import libcore.io.Libcore;
import libcore.io.StructUtsname;
import libcore.util.ZoneInfoDB;
/**
* Provides access to system-related information and resources including
* standard input and output. Enables clients to dynamically load native
* libraries. All methods of this class are accessed in a static way and the
* class itself can not be instantiated.
*
* @see Runtime
*/
public final class System {
/**
* Default input stream.
*/
public static final InputStream in;
/**
* Default output stream.
*/
public static final PrintStream out;
/**
* Default error output stream.
*/
public static final PrintStream err;
private static final String lineSeparator;
private static Properties systemProperties;
static {
// TODO: all three streams are buffered in Harmony.
err = new PrintStream(new FileOutputStream(FileDescriptor.err));
out = new PrintStream(new FileOutputStream(FileDescriptor.out));
in = new FileInputStream(FileDescriptor.in);
lineSeparator = System.getProperty("line.separator");
}
/**
* Sets the standard input stream to the given user defined input stream.
*
* @param newIn
* the user defined input stream to set as the standard input
* stream.
*/
public static void setIn(InputStream newIn) {
setFieldImpl("in", "Ljava/io/InputStream;", newIn);
}
/**
* Sets the standard output stream to the given user defined output stream.
*
* @param newOut
* the user defined output stream to set as the standard output
* stream.
*/
public static void setOut(PrintStream newOut) {
setFieldImpl("out", "Ljava/io/PrintStream;", newOut);
}
/**
* Sets the standard error output stream to the given user defined output
* stream.
*
* @param newErr
* the user defined output stream to set as the standard error
* output stream.
*/
public static void setErr(PrintStream newErr) {
setFieldImpl("err", "Ljava/io/PrintStream;", newErr);
}
/**
* Prevents this class from being instantiated.
*/
private System() {
}
/**
* Copies {@code length} elements from the array {@code src},
* starting at offset {@code srcPos}, into the array {@code dst},
* starting at offset {@code dstPos}.
*
* @param src
* the source array to copy the content.
* @param srcPos
* the starting index of the content in {@code src}.
* @param dst
* the destination array to copy the data into.
* @param dstPos
* the starting index for the copied content in {@code dst}.
* @param length
* the number of elements to be copied.
*/
public static native void arraycopy(Object src, int srcPos, Object dst, int dstPos, int length);
/**
* Returns the current system time in milliseconds since January 1, 1970
* 00:00:00 UTC. This method shouldn't be used for measuring timeouts or
* other elapsed time measurements, as changing the system time can affect
* the results.
*
* @return the local system time in milliseconds.
*/
public static native long currentTimeMillis();
/**
* Returns the current timestamp of the most precise timer available on the
* local system. This timestamp can only be used to measure an elapsed
* period by comparing it against another timestamp. It cannot be used as a
* very exact system time expression.
*
* @return the current timestamp in nanoseconds.
*/
public static native long nanoTime();
/**
* Causes the VM to stop running and the program to exit. If
* {@link #runFinalizersOnExit(boolean)} has been previously invoked with a
* {@code true} argument, then all objects will be properly
* garbage-collected and finalized first.
*
* @param code
* the return code.
*/
public static void exit(int code) {
Runtime.getRuntime().exit(code);
}
/**
* Indicates to the VM that it would be a good time to run the
* garbage collector. Note that this is a hint only. There is no guarantee
* that the garbage collector will actually be run.
*/
public static void gc() {
Runtime.getRuntime().gc();
}
/**
* Returns the value of the environment variable with the given name {@code
* var}.
*
* @param name
* the name of the environment variable.
* @return the value of the specified environment variable or {@code null}
* if no variable exists with the given name.
*/
public static String getenv(String name) {
return getenv(name, null);
}
private static String getenv(String name, String defaultValue) {
if (name == null) {
throw new NullPointerException("name == null");
}
String value = Libcore.os.getenv(name);
return (value != null) ? value : defaultValue;
}
/*
* Returns an environment variable. No security checks are performed.
* @param var the name of the environment variable
* @return the value of the specified environment variable
*/
private static native String getEnvByName(String name);
/**
* Returns an unmodifiable map of all available environment variables.
*
* @return the map representing all environment variables.
*/
public static Map<String, String> getenv() {
Map<String, String> map = new HashMap<String, String>();
for (String entry : Libcore.os.environ()) {
int index = entry.indexOf('=');
if (index != -1) {
map.put(entry.substring(0, index), entry.substring(index + 1));
}
}
return new SystemEnvironment(map);
}
/**
* Returns the inherited channel from the creator of the current virtual
* machine.
*
* @return the inherited {@link Channel} or {@code null} if none exists.
* @throws IOException
* if an I/O error occurred.
* @see SelectorProvider
* @see SelectorProvider#inheritedChannel()
*/
public static Channel inheritedChannel() throws IOException {
return SelectorProvider.provider().inheritedChannel();
}
/**
* Returns the system properties. Note that this is not a copy, so that
* changes made to the returned Properties object will be reflected in
* subsequent calls to getProperty and getProperties.
*
* @return the system properties.
*/
public static Properties getProperties() {
if (systemProperties == null) {
initSystemProperties();
}
return systemProperties;
}
private static void initSystemProperties() {
VMRuntime runtime = VMRuntime.getRuntime();
Properties p = new Properties();
String projectUrl = "http://www.android.com/";
String projectName = "The Android Project";
p.put("java.boot.class.path", runtime.bootClassPath());
p.put("java.class.path", runtime.classPath());
// None of these four are meaningful on Android, but these keys are guaranteed
// to be present for System.getProperty. For java.class.version, we use the maximum
// class file version that dx currently supports.
p.put("java.class.version", "50.0");
p.put("java.compiler", "");
p.put("java.ext.dirs", "");
p.put("java.version", "0");
p.put("java.home", getenv("JAVA_HOME", "/system"));
p.put("java.io.tmpdir", "/tmp");
p.put("java.library.path", getenv("LD_LIBRARY_PATH"));
p.put("java.specification.name", "Dalvik Core Library");
p.put("java.specification.vendor", projectName);
p.put("java.specification.version", "0.9");
p.put("java.vendor", projectName);
p.put("java.vendor.url", projectUrl);
p.put("java.vm.name", "Dalvik");
p.put("java.vm.specification.name", "Dalvik Virtual Machine Specification");
p.put("java.vm.specification.vendor", projectName);
p.put("java.vm.specification.version", "0.9");
p.put("java.vm.vendor", projectName);
p.put("java.vm.version", runtime.vmVersion());
p.put("file.separator", "/");
p.put("line.separator", "\n");
p.put("path.separator", ":");
p.put("java.runtime.name", "Android Runtime");
p.put("java.runtime.version", "0.9");
p.put("java.vm.vendor.url", projectUrl);
p.put("file.encoding", "UTF-8");
p.put("user.language", "en");
p.put("user.region", "US");
p.put("user.home", getenv("HOME", ""));
p.put("user.name", getenv("USER", ""));
StructUtsname info = Libcore.os.uname();
p.put("os.arch", info.machine);
p.put("os.name", info.sysname);
p.put("os.version", info.release);
// Undocumented Android-only properties.
p.put("android.icu.library.version", ICU.getIcuVersion());
p.put("android.icu.unicode.version", ICU.getUnicodeVersion());
// TODO: it would be nice to have this but currently it causes circularity.
// p.put("android.tzdata.version", ZoneInfoDB.getVersion());
parsePropertyAssignments(p, specialProperties());
// Override built-in properties with settings from the command line.
parsePropertyAssignments(p, runtime.properties());
systemProperties = p;
}
/**
* Returns an array of "key=value" strings containing information not otherwise
* easily available, such as #defined library versions.
*/
private static native String[] specialProperties();
/**
* Adds each element of 'assignments' to 'p', treating each element as an
* assignment in the form "key=value".
*/
private static void parsePropertyAssignments(Properties p, String[] assignments) {
for (String assignment : assignments) {
int split = assignment.indexOf('=');
String key = assignment.substring(0, split);
String value = assignment.substring(split + 1);
p.put(key, value);
}
}
/**
* Returns the value of a particular system property or {@code null} if no
* such property exists.
*
* <p>The following properties are always provided by the Dalvik VM:
* <p><table BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
* <tr BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
* <td><b>Name</b></td> <td><b>Meaning</b></td> <td><b>Example</b></td></tr>
* <tr><td>file.separator</td> <td>{@link java.io.File#separator}</td> <td>{@code /}</td></tr>
*
* <tr><td>java.class.path</td> <td>System class path</td> <td>{@code .}</td></tr>
* <tr><td>java.class.version</td> <td>(Not useful on Android)</td> <td>{@code 50.0}</td></tr>
* <tr><td>java.compiler</td> <td>(Not useful on Android)</td> <td>Empty</td></tr>
* <tr><td>java.ext.dirs</td> <td>(Not useful on Android)</td> <td>Empty</td></tr>
* <tr><td>java.home</td> <td>Location of the VM on the file system</td> <td>{@code /system}</td></tr>
* <tr><td>java.io.tmpdir</td> <td>See {@link java.io.File#createTempFile}</td> <td>{@code /sdcard}</td></tr>
* <tr><td>java.library.path</td> <td>Search path for JNI libraries</td> <td>{@code /system/lib}</td></tr>
* <tr><td>java.vendor</td> <td>Human-readable VM vendor</td> <td>{@code The Android Project}</td></tr>
* <tr><td>java.vendor.url</td> <td>URL for VM vendor's web site</td> <td>{@code http://www.android.com/}</td></tr>
* <tr><td>java.version</td> <td>(Not useful on Android)</td> <td>{@code 0}</td></tr>
*
* <tr><td>java.specification.version</td> <td>VM libraries version</td> <td>{@code 0.9}</td></tr>
* <tr><td>java.specification.vendor</td> <td>VM libraries vendor</td> <td>{@code The Android Project}</td></tr>
* <tr><td>java.specification.name</td> <td>VM libraries name</td> <td>{@code Dalvik Core Library}</td></tr>
* <tr><td>java.vm.version</td> <td>VM implementation version</td> <td>{@code 1.2.0}</td></tr>
* <tr><td>java.vm.vendor</td> <td>VM implementation vendor</td> <td>{@code The Android Project}</td></tr>
* <tr><td>java.vm.name</td> <td>VM implementation name</td> <td>{@code Dalvik}</td></tr>
* <tr><td>java.vm.specification.version</td> <td>VM specification version</td> <td>{@code 0.9}</td></tr>
* <tr><td>java.vm.specification.vendor</td> <td>VM specification vendor</td> <td>{@code The Android Project}</td></tr>
* <tr><td>java.vm.specification.name</td> <td>VM specification name</td> <td>{@code Dalvik Virtual Machine Specification}</td></tr>
*
* <tr><td>line.separator</td> <td>The system line separator</td> <td>{@code \n}</td></tr>
*
* <tr><td>os.arch</td> <td>OS architecture</td> <td>{@code armv7l}</td></tr>
* <tr><td>os.name</td> <td>OS (kernel) name</td> <td>{@code Linux}</td></tr>
* <tr><td>os.version</td> <td>OS (kernel) version</td> <td>{@code 2.6.32.9-g103d848}</td></tr>
*
* <tr><td>path.separator</td> <td>See {@link java.io.File#pathSeparator}</td> <td>{@code :}</td></tr>
*
* <tr><td>user.dir</td> <td>Base of non-absolute paths</td> <td>{@code /}</td></tr>
* <tr><td>user.home</td> <td>(Not useful on Android)</td> <td>Empty</td></tr>
* <tr><td>user.name</td> <td>(Not useful on Android)</td> <td>Empty</td></tr>
*
* </table>
*
* <p>It is a mistake to try to override any of these. Doing so will have unpredictable results.
*
* @param propertyName
* the name of the system property to look up.
* @return the value of the specified system property or {@code null} if the
* property doesn't exist.
*/
public static String getProperty(String propertyName) {
return getProperty(propertyName, null);
}
/**
* Returns the value of a particular system property. The {@code
* defaultValue} will be returned if no such property has been found.
*
* @param prop
* the name of the system property to look up.
* @param defaultValue
* the return value if the system property with the given name
* does not exist.
* @return the value of the specified system property or the {@code
* defaultValue} if the property does not exist.
*/
public static String getProperty(String prop, String defaultValue) {
if (prop.isEmpty()) {
throw new IllegalArgumentException();
}
return getProperties().getProperty(prop, defaultValue);
}
/**
* Sets the value of a particular system property.
*
* @param prop
* the name of the system property to be changed.
* @param value
* the value to associate with the given property {@code prop}.
* @return the old value of the property or {@code null} if the property
* didn't exist.
*/
public static String setProperty(String prop, String value) {
if (prop.isEmpty()) {
throw new IllegalArgumentException();
}
return (String) getProperties().setProperty(prop, value);
}
/**
* Removes a specific system property.
*
* @param key
* the name of the system property to be removed.
* @return the property value or {@code null} if the property didn't exist.
* @throws NullPointerException
* if the argument {@code key} is {@code null}.
* @throws IllegalArgumentException
* if the argument {@code key} is empty.
*/
public static String clearProperty(String key) {
if (key == null) {
throw new NullPointerException();
}
if (key.isEmpty()) {
throw new IllegalArgumentException();
}
return (String) getProperties().remove(key);
}
/**
* Returns the {@link java.io.Console} associated with this VM, or null.
* Not all VMs will have an associated console. A console is typically only
* available for programs run from the command line.
* @since 1.6
*/
public static Console console() {
return Console.getConsole();
}
/**
* Returns null. Android does not use {@code SecurityManager}. This method
* is only provided for source compatibility.
*
* @return null
*/
public static SecurityManager getSecurityManager() {
return null;
}
/**
* Returns an integer hash code for the parameter. The hash code returned is
* the same one that would be returned by the method {@code
* java.lang.Object.hashCode()}, whether or not the object's class has
* overridden hashCode(). The hash code for {@code null} is {@code 0}.
*
* @param anObject
* the object to calculate the hash code.
* @return the hash code for the given object.
* @see java.lang.Object#hashCode
*/
public static native int identityHashCode(Object anObject);
/**
* Returns the system's line separator. On Android, this is {@code "\n"}. The value
* comes from the value of the {@code line.separator} system property when the VM
* starts. Later changes to the property will not affect the value returned by this
* method.
* @since 1.7
* @hide 1.7 - fix documentation references to "line.separator" in Formatter.
*/
public static String lineSeparator() {
return lineSeparator;
}
/**
* Loads and links the dynamic library that is identified through the
* specified path. This method is similar to {@link #loadLibrary(String)},
* but it accepts a full path specification whereas {@code loadLibrary} just
* accepts the name of the library to load.
*
* @param pathName
* the path of the file to be loaded.
*/
public static void load(String pathName) {
Runtime.getRuntime().load(pathName, VMStack.getCallingClassLoader());
}
/**
* Loads and links the library with the specified name. The mapping of the
* specified library name to the full path for loading the library is
* implementation-dependent.
*
* @param libName
* the name of the library to load.
* @throws UnsatisfiedLinkError
* if the library could not be loaded.
*/
public static void loadLibrary(String libName) {
Runtime.getRuntime().loadLibrary(libName, VMStack.getCallingClassLoader());
}
/**
* @hide internal use only
*/
public static void logE(String message) {
log('E', message, null);
}
/**
* @hide internal use only
*/
public static void logE(String message, Throwable th) {
log('E', message, th);
}
/**
* @hide internal use only
*/
public static void logI(String message) {
log('I', message, null);
}
/**
* @hide internal use only
*/
public static void logI(String message, Throwable th) {
log('I', message, th);
}
/**
* @hide internal use only
*/
public static void logW(String message) {
log('W', message, null);
}
/**
* @hide internal use only
*/
public static void logW(String message, Throwable th) {
log('W', message, th);
}
private static native void log(char type, String message, Throwable th);
/**
* Provides a hint to the VM that it would be useful to attempt
* to perform any outstanding object finalization.
*/
public static void runFinalization() {
Runtime.getRuntime().runFinalization();
}
/**
* Ensures that, when the VM is about to exit, all objects are
* finalized. Note that all finalization which occurs when the system is
* exiting is performed after all running threads have been terminated.
*
* @param flag
* the flag determines if finalization on exit is enabled.
* @deprecated this method is unsafe.
*/
@SuppressWarnings("deprecation")
@Deprecated
public static void runFinalizersOnExit(boolean flag) {
Runtime.runFinalizersOnExit(flag);
}
/**
* Sets all system properties. This does not take a copy; the passed-in object is used
* directly. Passing null causes the VM to reinitialize the properties to how they were
* when the VM was started.
*/
public static void setProperties(Properties p) {
systemProperties = p;
}
/**
* Throws {@code SecurityException}.
*
* <p>Security managers do <i>not</i> provide a secure environment for
* executing untrusted code and are unsupported on Android. Untrusted code
* cannot be safely isolated within a single VM on Android.
*
* @param sm a security manager
* @throws SecurityException always
*/
public static void setSecurityManager(SecurityManager sm) {
if (sm != null) {
throw new SecurityException();
}
}
/**
* Returns the platform specific file name format for the shared library
* named by the argument.
*
* @param userLibName
* the name of the library to look up.
* @return the platform specific filename for the library.
*/
public static native String mapLibraryName(String userLibName);
/**
* Sets the value of the named static field in the receiver to the passed in
* argument.
*
* @param fieldName
* the name of the field to set, one of in, out, or err
* @param stream
* the new value of the field
*/
private static native void setFieldImpl(String fieldName, String signature, Object stream);
/**
* The unmodifiable environment variables map. System.getenv() specifies
* that this map must throw when passed non-String keys.
*/
static class SystemEnvironment extends AbstractMap<String, String> {
private final Map<String, String> map;
public SystemEnvironment(Map<String, String> map) {
this.map = Collections.unmodifiableMap(map);
}
@Override public Set<Entry<String, String>> entrySet() {
return map.entrySet();
}
@Override public String get(Object key) {
return map.get(toNonNullString(key));
}
@Override public boolean containsKey(Object key) {
return map.containsKey(toNonNullString(key));
}
@Override public boolean containsValue(Object value) {
return map.containsValue(toNonNullString(value));
}
private String toNonNullString(Object o) {
if (o == null) {
throw new NullPointerException();
}
return (String) o;
}
}
}