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8295803: Console should be usable in jshell and other environments
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Reviewed-by: jlaskey, alanb
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naotoj committed Dec 7, 2022
1 parent 5d4c71c commit 8a9911e
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Showing 17 changed files with 673 additions and 23 deletions.
49 changes: 35 additions & 14 deletions src/java.base/share/classes/java/io/Console.java
Original file line number Diff line number Diff line change
Expand Up @@ -25,10 +25,13 @@

package java.io;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.*;
import java.nio.charset.Charset;
import jdk.internal.access.JavaIOAccess;
import jdk.internal.access.SharedSecrets;
import jdk.internal.io.JdkConsoleProvider;
import jdk.internal.util.StaticProperty;
import sun.nio.cs.StreamDecoder;
import sun.nio.cs.StreamEncoder;
Expand All @@ -45,7 +48,7 @@
* output streams then its console will exist and will typically be
* connected to the keyboard and display from which the virtual machine
* was launched. If the virtual machine is started automatically, for
* example by a background job scheduler, then it will typically not
* example by a background job scheduler, then it may not
* have a console.
* <p>
* If this virtual machine has a console then it is represented by a
Expand Down Expand Up @@ -93,7 +96,7 @@
* @since 1.6
*/

public final class Console implements Flushable
public class Console implements Flushable
{
/**
* Retrieves the unique {@link java.io.PrintWriter PrintWriter} object
Expand Down Expand Up @@ -592,25 +595,43 @@ public int read(char[] cbuf, int offset, int length)

CHARSET = cs;

cons = instantiateConsole(istty);

// Set up JavaIOAccess in SharedSecrets
SharedSecrets.setJavaIOAccess(new JavaIOAccess() {
public Console console() {
if (istty) {
if (cons == null)
cons = new Console();
return cons;
}
return null;
}

public Charset charset() {
return CHARSET;
return cons;
}
});
}
private static Console cons;

@SuppressWarnings("removal")
private static Console instantiateConsole(boolean istty) {
try {
// Try loading providers
PrivilegedAction<Console> pa = () -> {
var consModName = System.getProperty("jdk.console",
JdkConsoleProvider.DEFAULT_PROVIDER_MODULE_NAME);
return ServiceLoader.load(ModuleLayer.boot(), JdkConsoleProvider.class).stream()
.map(ServiceLoader.Provider::get)
.filter(jcp -> consModName.equals(jcp.getClass().getModule().getName()))
.map(jcp -> jcp.console(istty, CHARSET))
.filter(Objects::nonNull)
.findAny()
.map(jc -> (Console) new ProxyingConsole(jc))
.orElse(istty ? new Console() : null);
};
return AccessController.doPrivileged(pa);
} catch (ServiceConfigurationError ignore) {
// default to built-in Console
return istty ? new Console() : null;
}
}

private static final Console cons;
private static native boolean istty();
private Console() {

Console() {
readLock = new Object();
writeLock = new Object();
out = StreamEncoder.forOutputStreamWriter(
Expand Down
9 changes: 9 additions & 0 deletions src/java.base/share/classes/java/io/PrintWriter.java
Original file line number Diff line number Diff line change
Expand Up @@ -208,6 +208,15 @@ public PrintWriter(String fileName) throws FileNotFoundException {
false);
}

/* Package private constructor, using the specified lock
* for synchronization.
*/
PrintWriter(Writer out, Object lock) {
super(lock);
this.out = out;
this.autoFlush = false;
}

/* Private constructor */
private PrintWriter(Charset charset, File file)
throws FileNotFoundException
Expand Down
198 changes: 198 additions & 0 deletions src/java.base/share/classes/java/io/ProxyingConsole.java
Original file line number Diff line number Diff line change
@@ -0,0 +1,198 @@
/*
* Copyright (c) 2022, 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.io;

import java.nio.charset.Charset;
import jdk.internal.io.JdkConsole;

/**
* Console implementation for internal use. Custom Console delegate may be
* provided with jdk.internal.io.JdkConsoleProvider.
*/
final class ProxyingConsole extends Console {
private final JdkConsole delegate;
private final Object readLock;
private final Object writeLock;
private final Reader reader;
private final PrintWriter printWriter;

ProxyingConsole(JdkConsole delegate) {
this.delegate = delegate;
readLock = new Object();
writeLock = new Object();
reader = new WrappingReader(delegate.reader(), readLock);
printWriter = new WrappingWriter(delegate.writer(), writeLock);
}

/**
* {@inheritDoc}
*/
@Override
public PrintWriter writer() {
return printWriter;
}

/**
* {@inheritDoc}
*/
@Override
public Reader reader() {
return reader;
}

/**
* {@inheritDoc}
*/
@Override
public Console format(String fmt, Object ... args) {
synchronized (writeLock) {
delegate.format(fmt, args);
}
return this;
}

/**
* {@inheritDoc}
*/
@Override
public Console printf(String format, Object ... args) {
synchronized (writeLock) {
delegate.printf(format, args);
}
return this;
}

/**
* {@inheritDoc}
*/
@Override
public String readLine(String fmt, Object ... args) {
synchronized (writeLock) {
synchronized (readLock) {
return delegate.readLine(fmt, args);
}
}
}

/**
* {@inheritDoc}
*/
@Override
public String readLine() {
synchronized (readLock) {
return delegate.readLine();
}
}

/**
* {@inheritDoc}
*/
@Override
public char[] readPassword(String fmt, Object ... args) {
synchronized (writeLock) {
synchronized (readLock) {
return delegate.readPassword(fmt, args);
}
}
}

/**
* {@inheritDoc}
*/
@Override
public char[] readPassword() {
synchronized (readLock) {
return delegate.readPassword();
}
}

/**
* {@inheritDoc}
*/
@Override
public void flush() {
delegate.flush();
}

/**
* {@inheritDoc}
*/
@Override
public Charset charset() {
return delegate.charset();
}

private static class WrappingReader extends Reader {
private final Reader r;
private final Object lock;

WrappingReader(Reader r, Object lock) {
super(lock);
this.r = r;
this.lock = lock;
}

@Override
public int read(char[] cbuf, int off, int len) throws IOException {
synchronized (lock) {
return r.read(cbuf, off, len);
}
}

@Override
public void close() {
// no-op, per Console's spec
}
}

private static class WrappingWriter extends PrintWriter {
private final PrintWriter pw;
private final Object lock;

public WrappingWriter(PrintWriter pw, Object lock) {
super(pw, lock);
this.pw = pw;
this.lock = lock;
}

@Override
public void write(char[] cbuf, int off, int len) {
synchronized (lock) {
pw.write(cbuf, off, len);
}
}

@Override
public void flush() {
pw.flush();
}

@Override
public void close() {
// no-op, per Console's spec
}
}
}
10 changes: 9 additions & 1 deletion src/java.base/share/classes/java/lang/System.java
Original file line number Diff line number Diff line change
Expand Up @@ -189,6 +189,9 @@ private System() {
*/
public static final PrintStream err = null;

// Holder for the initial value of `in`, set within `initPhase1()`.
private static InputStream initialIn;

// indicates if a security manager is possible
private static final int NEVER = 1;
private static final int MAYBE = 2;
Expand Down Expand Up @@ -2174,7 +2177,8 @@ private static void initPhase1() {
FileInputStream fdIn = new FileInputStream(FileDescriptor.in);
FileOutputStream fdOut = new FileOutputStream(FileDescriptor.out);
FileOutputStream fdErr = new FileOutputStream(FileDescriptor.err);
setIn0(new BufferedInputStream(fdIn));
initialIn = new BufferedInputStream(fdIn);
setIn0(initialIn);
// stdout/err.encoding are set when the VM is associated with the terminal,
// thus they are equivalent to Console.charset(), otherwise the encodings
// of those properties default to native.encoding
Expand Down Expand Up @@ -2485,6 +2489,10 @@ public int encodeASCII(char[] src, int srcOff, byte[] dst, int dstOff, int len)
return StringCoding.implEncodeAsciiArray(src, srcOff, dst, dstOff, len);
}

public InputStream initialSystemIn() {
return initialIn;
}

public void setCause(Throwable t, Throwable cause) {
t.setCause(cause);
}
Expand Down
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*
* Copyright (c) 2005, 2021, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2005, 2022, 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
Expand All @@ -26,9 +26,7 @@
package jdk.internal.access;

import java.io.Console;
import java.nio.charset.Charset;

public interface JavaIOAccess {
Console console();
Charset charset();
}
Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@

package jdk.internal.access;

import java.io.InputStream;
import java.lang.annotation.Annotation;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodType;
Expand Down Expand Up @@ -363,6 +364,12 @@ public interface JavaLangAccess {
*/
int decodeASCII(byte[] src, int srcOff, char[] dst, int dstOff, int len);

/**
* Returns the initial `System.in` to determine if it is replaced
* with `System.setIn(newIn)` method
*/
InputStream initialSystemIn();

/**
* Encodes ASCII codepoints as possible from the source array into
* the destination byte array, assuming that the encoding is ASCII
Expand Down

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