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/*
 * Copyright (c) 2017, 2017, 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 com.oracle.svm.hosted.image;

import java.io.FileDescriptor;
import java.lang.reflect.Field;
import java.nio.MappedByteBuffer;

import org.graalvm.nativeimage.Feature;

import com.oracle.graal.pointsto.constraints.UnsupportedFeatureException;
import com.oracle.svm.core.annotate.AutomaticFeature;
import com.oracle.svm.core.option.SubstrateOptionsParser;
import com.oracle.svm.core.util.VMError;
import com.oracle.svm.hosted.ClassInitializationFeature;

/**
 * Complain if there are types that can not move from the image generator heap to the image heap.
 */
@AutomaticFeature
public class DisallowedImageHeapObjectFeature implements Feature {

    @Override
    public void duringSetup(DuringSetupAccess access) {
        access.registerObjectReplacer(DisallowedImageHeapObjectFeature::replacer);
    }

    private static Object replacer(Object original) {
        /* Started Threads can not be in the image heap. */
        if (original instanceof Thread) {
            final Thread asThread = (Thread) original;
            if (asThread.getState() != Thread.State.NEW) {
                throw error("Detected a started Thread in the image heap. " +
                                "Threads running in the image generator are no longer running at image run time. ");
            }
        }
        /* FileDescriptors can not be in the image heap. */
        if (original instanceof FileDescriptor) {
            final FileDescriptor asFileDescriptor = (FileDescriptor) original;
            /* Except for a few well-known FileDescriptors. */
            if (!((asFileDescriptor == FileDescriptor.in) || (asFileDescriptor == FileDescriptor.out) || (asFileDescriptor == FileDescriptor.err) || (!asFileDescriptor.valid()))) {
                throw error("Detected a FileDescriptor in the image heap. " +
                                "File descriptors opened during image generation are no longer open at image run time, and the files might not even be present anymore at image run time. ");
            }
        }
        /* Direct ByteBuffers can not be in the image heap. */
        if (original instanceof MappedByteBuffer) {
            MappedByteBuffer buffer = (MappedByteBuffer) original;
            /*
             * We allow 0-length non-file-based direct buffers, see comment on
             * Targt_java_nio_DirectByteBuffer.
             */
            if (buffer.capacity() != 0 || getFileDescriptor(buffer) != null) {
                throw error("Detected a direct/mapped ByteBuffer in the image heap. " +
                                "A direct ByteBuffer has a pointer to unmanaged C memory, and C memory from the image generator is not available at image run time. " +
                                "A mapped ByteBuffer references a file descriptor, which is no longer open and mapped at run time. ");
            }
        }

        /* ZipFiles can not be in the image heap. */
        if (original instanceof java.util.zip.ZipFile) {
            throw error("Detected a ZipFile object in the image heap. " +
                            "A ZipFile object contains pointers to unmanaged C memory and file descriptors, and these resources are no longer available at image run time. ");
        }

        return original;
    }

    private static RuntimeException error(String msg) {
        throw new UnsupportedFeatureException(msg +
                        "The object was probably created by a class initializer and is reachable from a static field. " +
                        "By default, all class initialization is done during native image building." +
                        "You can manually delay class initialization to image run time by using the option " +
                        SubstrateOptionsParser.commandArgument(ClassInitializationFeature.Options.DelayClassInitialization, "") + ". " +
                        "Or you can write your own initialization methods and call them explicitly from your main entry point.");
    }

    private static final Field FILE_DESCRIPTOR_FIELD;

    static {
        try {
            FILE_DESCRIPTOR_FIELD = MappedByteBuffer.class.getDeclaredField("fd");
            FILE_DESCRIPTOR_FIELD.setAccessible(true);
        } catch (ReflectiveOperationException ex) {
            throw VMError.shouldNotReachHere(ex);
        }
    }

    private static FileDescriptor getFileDescriptor(MappedByteBuffer buffer) {
        try {
            return (FileDescriptor) FILE_DESCRIPTOR_FIELD.get(buffer);
        } catch (ReflectiveOperationException ex) {
            throw VMError.shouldNotReachHere(ex);
        }
    }
}