/*
 * Copyright (c) 2019, 2019, 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
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package com.oracle.svm.core.jdk14;

import com.oracle.svm.core.annotate.Alias;
import com.oracle.svm.core.annotate.RecomputeFieldValue;
import com.oracle.svm.core.annotate.Substitute;
import com.oracle.svm.core.annotate.TargetClass;
import com.oracle.svm.core.jdk.JDK14OrLater;
import com.oracle.svm.core.heap.Target_jdk_internal_ref_Cleaner;

import java.io.FileDescriptor;
import jdk.internal.access.foreign.MemorySegmentProxy;

We disallow direct byte buffers (MappedByteBuffer instances) in the image heap, with one exception: we allow 0-length non-file-based buffers. For example, Netty has a singleton empty buffer referenced from a static field, and a lot of Netty classes reference this buffer statically. Such buffers do actually have an address to memory that is allocated during image generation and therefore no longer available at run time. But since the capacity is 0, no memory can ever be accessed. We therefore allow this "dangling" address. However, we must never call free() for that address, so we remove the Cleaner registered for the buffer by resetting the field cleaner. /**
 * We disallow direct byte buffers ({@link java.nio.MappedByteBuffer} instances) in the image heap,
 * with one exception: we allow 0-length non-file-based buffers. For example, Netty has a singleton
 * empty buffer referenced from a static field, and a lot of Netty classes reference this buffer
 * statically.
 *
 * Such buffers do actually have an address to memory that is allocated during image generation and
 * therefore no longer available at run time. But since the capacity is 0, no memory can ever be
 * accessed. We therefore allow this "dangling" address. However, we must never call free() for that
 * address, so we remove the Cleaner registered for the buffer by resetting the field
 * {@link #cleaner}.
 */
@TargetClass(className = "java.nio.DirectByteBuffer", onlyWith = JDK14OrLater.class)
@SuppressWarnings("unused")
final class Target_java_nio_DirectByteBuffer_JDK14OrLater {
    @Alias @RecomputeFieldValue(kind = RecomputeFieldValue.Kind.Reset) //
    Target_jdk_internal_ref_Cleaner cleaner;

    @Alias
    protected Target_java_nio_DirectByteBuffer_JDK14OrLater(int cap, long addr, FileDescriptor fd, Runnable unmapper, boolean isSync, MemorySegmentProxy segment) {
    }

}

@TargetClass(className = "java.nio.DirectByteBufferR", onlyWith = JDK14OrLater.class)
@SuppressWarnings("unused")
final class Target_java_nio_DirectByteBufferR_JDK14OrLater {

    @Alias
    protected Target_java_nio_DirectByteBufferR_JDK14OrLater(int cap, long addr, FileDescriptor fd, Runnable unmapper, boolean isSync, MemorySegmentProxy segment) {
    }

}

@TargetClass(className = "sun.nio.ch.Util", onlyWith = JDK14OrLater.class)
final class Target_sun_nio_ch_Util {

    @Substitute
    private static Target_java_nio_DirectByteBuffer_JDK14OrLater newMappedByteBuffer(int size, long addr, FileDescriptor fd, Runnable unmapper, boolean isSync) {
        return new Target_java_nio_DirectByteBuffer_JDK14OrLater(size, addr, fd, unmapper, isSync, null);
    }

    @Substitute
    static Target_java_nio_DirectByteBufferR_JDK14OrLater newMappedByteBufferR(int size, long addr, FileDescriptor fd, Runnable unmapper, boolean isSync) {
        return new Target_java_nio_DirectByteBufferR_JDK14OrLater(size, addr, fd, unmapper, isSync, null);
    }

}