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8143394: PushbackReader throws NullPointerException

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Synchronize on lock in close() to avoid NPE from read()-close() race.

Reviewed-by: alanb, dfuchs
This commit is contained in:
Brian Burkhalter 2015-12-15 09:02:46 -08:00
parent f98f28d1df
commit 7a0c72ef9c
4 changed files with 134 additions and 10 deletions
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9
jdk/src/java.base/share/classes/java/io/CharArrayReader.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 1996, 2005, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1996, 2015, 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
@ -225,9 +225,12 @@ public class CharArrayReader extends Reader {
* Closes the stream and releases any system resources associated with
* it. Once the stream has been closed, further read(), ready(),
* mark(), reset(), or skip() invocations will throw an IOException.
* Closing a previously closed stream has no effect.
* Closing a previously closed stream has no effect. This method will block
* while there is another thread blocking on the reader.
*/
public void close() {
buf = null;
synchronized (lock) {
buf = null;
}
}
}

11
jdk/src/java.base/share/classes/java/io/PushbackReader.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1996, 2015, 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
@ -241,13 +241,16 @@ public class PushbackReader extends FilterReader {
* Closes the stream and releases any system resources associated with
* it. Once the stream has been closed, further read(),
* unread(), ready(), or skip() invocations will throw an IOException.
* Closing a previously closed stream has no effect.
* Closing a previously closed stream has no effect. This method will block
* while there is another thread blocking on the reader.
*
* @exception IOException If an I/O error occurs
*/
public void close() throws IOException {
super.close();
buf = null;
synchronized (lock) {
super.close();
buf = null;
}
}
/**

9
jdk/src/java.base/share/classes/java/io/StringReader.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1996, 2015, 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
@ -194,9 +194,12 @@ public class StringReader extends Reader {
* Closes the stream and releases any system resources associated with
* it. Once the stream has been closed, further read(),
* ready(), mark(), or reset() invocations will throw an IOException.
* Closing a previously closed stream has no effect.
* Closing a previously closed stream has no effect. This method will block
* while there is another thread blocking on the reader.
*/
public void close() {
str = null;
synchronized (lock) {
str = null;
}
}
}

115
jdk/test/java/io/PushbackReader/ReadCloseRaceNPE.java Normal file
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@ -0,0 +1,115 @@
/*
* Copyright (c) 2015, 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.
*
* 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.
*/
/*
* @test
* @bug 8143394
* @summary Check for NullPointerException in race between read() and close().
*/
import java.io.CharArrayReader;
import java.io.IOException;
import java.io.PushbackReader;
import java.io.Reader;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Supplier;
public class ReadCloseRaceNPE {
private static final int BUF_SIZE = 1000;
private static final long TIMEOUT_MS = 3000;
private static final List<Exception> failures = new ArrayList<>();
private static void testReader(final Supplier<Reader> readerSupplier)
throws InterruptedException {
AtomicReference<Reader> readerRef =
new AtomicReference<>(readerSupplier.get());
AtomicBoolean isFinished = new AtomicBoolean();
Runnable readTask = () -> {
long startTime = System.currentTimeMillis();
while (System.currentTimeMillis() - startTime < TIMEOUT_MS) {
try {
readerRef.get().read();
} catch (Exception e) {
if (!(e instanceof IOException)) {
failures.add(e);
break;
}
readerRef.set(readerSupplier.get());
}
}
isFinished.set(true);
};
Runnable closeTask = () -> {
while (!isFinished.get()) {
try {
readerRef.get().close();
} catch (Exception e) {
if (!(e instanceof IOException)) {
e.printStackTrace();
}
}
}
};
Thread readThread = new Thread(readTask);
Thread closeThread = new Thread(closeTask);
readThread.start();
closeThread.start();
readThread.join();
closeThread.join();
}
public static void main(String[] args) throws Throwable {
final String s = "Two riders were approaching.\\n";
Supplier<Reader> charPushbackReaderSupplier = () -> {
char buf[] = new char[s.length()];
s.getChars(0, s.length(), buf, 0);
CharArrayReader in = new CharArrayReader(buf);
return new PushbackReader(in, BUF_SIZE);
};
testReader(charPushbackReaderSupplier);
Supplier<Reader> stringPushbackReaderSupplier = () -> {
StringReader in = new StringReader(s);
return new PushbackReader(in, BUF_SIZE);
};
testReader(stringPushbackReaderSupplier);
if (!failures.isEmpty()) {
failures.stream().forEach((x) -> ((Exception) x).printStackTrace());
throw new RuntimeException("PushbackReaderNPE failed");
}
}
}