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8319817: Charset constructor should make defensive copy of aliases
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Reviewed-by: rriggs, alanb, bpb, iris, jpai
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naotoj committed Nov 20, 2023
1 parent 0712b22 commit d6d7bdc
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Showing 2 changed files with 75 additions and 2 deletions.
8 changes: 6 additions & 2 deletions src/java.base/share/classes/java/nio/charset/
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Expand Up @@ -42,7 +42,6 @@
import java.util.Locale;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.ServiceConfigurationError;
import java.util.ServiceLoader;
import java.util.Set;
Expand Down Expand Up @@ -706,7 +705,12 @@ public static Charset defaultCharset() {
* If the canonical name or any of the aliases are illegal
protected Charset(String canonicalName, String[] aliases) {
String[] as = Objects.requireNonNullElse(aliases, zeroAliases);
String[] as =
aliases == null ?
zeroAliases :
VM.isSystemDomainLoader(getClass().getClassLoader()) ?
aliases :
Arrays.copyOf(aliases, aliases.length);

// Skip checks for the standard, built-in Charsets we always load
// during initialization.
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69 changes: 69 additions & 0 deletions test/jdk/java/nio/charset/Charset/
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@@ -0,0 +1,69 @@
* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
* 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.
* 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 if you need additional information or have any
* questions.

/* @test
* @bug 8319817
* @summary Check that aliases cannot be mutated
* @run junit AliasesCopy

import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.util.Set;

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertIterableEquals;

public class AliasesCopy {
private static final Set<String> ALIASES_SET = Set.of("foo-alias");
private static final String[] ALIASES_ARRAY = ALIASES_SET.toArray(String[]::new);

public void aliasesCopy() {
final FooCharset cs = new FooCharset(ALIASES_ARRAY);
ALIASES_ARRAY[0] = "bar-alias";
assertIterableEquals(ALIASES_SET, cs.aliases());

private static final class FooCharset extends Charset {
private FooCharset(String[] aliases) {
super("foo", aliases);

public CharsetEncoder newEncoder() {
throw new RuntimeException("not implemented");

public CharsetDecoder newDecoder() {
throw new RuntimeException("not implemented");

public boolean contains(Charset cs) {
throw new RuntimeException("not implemented");

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