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/* @test
 * @bug 8303260
 * @summary Test transferFrom to a position greater than the file size
 * @library .. /test/lib
 * @build jdk.test.lib.RandomFactory
 * @run junit TransferFromExtend
 * @key randomness
 */

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.FileChannel;
import java.nio.channels.ReadableByteChannel;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Random;
import java.util.stream.Stream;

import static java.nio.file.StandardOpenOption.*;

import jdk.test.lib.RandomFactory;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;

import static org.junit.jupiter.api.Assertions.*;

public class TransferFromExtend {
    private static final Random RND = RandomFactory.getRandom();

    private static final Path DIR = Path.of(System.getProperty("test.dir", "."));

    private static Stream<Arguments> paramProvider(int transferSizeMin,
                                                   int transferSizeMax) {
        List<Arguments> list = new ArrayList<Arguments>();
        int sizeDelta = transferSizeMax - transferSizeMin;
        for (int i = 0; i < 10; i++) {
            Arguments args =
                Arguments.of(RND.nextInt(1024),
                             transferSizeMin + RND.nextInt(sizeDelta),
                             1 + RND.nextInt(2047));
            list.add(args);
        }
        return list.stream();
    }

    //
    // transfer size must be greater than the threshold
    // sun.nio.ch.FileChannelImpl::MAPPED_TRANSFER_THRESHOLD (16K)
    // for a mapped transfer to be used when direct is unavailable
    //
    private static Stream<Arguments> fastParamProvider() {
        return paramProvider(16*1024 + 1, 500*1024);
    }

    private static Stream<Arguments> readingByteChannelParamProvider() {
        return paramProvider(1, 64*1024);
    }

    /*
     * This method tests the optimized path for transferring from a file
     * source to a file destination.
     */
    @ParameterizedTest
    @MethodSource("fastParamProvider")
    void fromFileChannel(long initialPosition, int bufSize, long offset)
        throws IOException
    {
        Path file = Files.createTempFile(DIR, "foo", "bar");
        try (FileChannel src = FileChannel.open(file, DELETE_ON_CLOSE,
                                                READ, WRITE)) {
            byte[] bytes = new byte[bufSize];
            RND.nextBytes(bytes);
            ByteBuffer buf = ByteBuffer.wrap(bytes);
            int total = 0;
            while (total < bufSize) {
                int n = src.write(ByteBuffer.wrap(bytes), 0);
                assertTrue(n >= 0, n + " < " + 0);
                total += n;
            }
            testTransferFrom(src, src.size(), initialPosition, offset, bytes);
        }
    }

    //
    // Test the arbitrary source path. This method tests the
    // generic path on all platforms.
    //
    @ParameterizedTest
    @MethodSource("readingByteChannelParamProvider")
    void fromReadingByteChannel(long initialPosition, int bufSize, long offset)
        throws IOException
    {
        byte[] bytes = new byte[bufSize];
        RND.nextBytes(bytes);
        ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
        try (ReadableByteChannel src = Channels.newChannel(bais)) {
            testTransferFrom(src, bufSize, initialPosition, offset, bytes);
        }
    }

    /**
     * Tests transferring bytes to a FileChannel from a ReadableByteChannel.
     *
     * @param src        the source of the bytes to transfer
     * @param count the  number of bytes to transfer
     * @param initialPos the position of the target channel before the transfer
     * @param offset     the offset beyong the end of the target channel
     * @param bytes      the bytes expected to be transferred
     */
    private static void testTransferFrom(ReadableByteChannel src, long count,
                                         long initialPos, long offset,
                                         byte[] bytes)
        throws IOException
    {
        Path file = Files.createTempFile(DIR, "foo", "bar");
        try (FileChannel target = FileChannel.open(file, DELETE_ON_CLOSE,
                                                   READ, WRITE)) {
            target.position(initialPos);
            assertEquals(1, target.write(ByteBuffer.wrap(new byte[] {(byte)42})));

            long position = target.size() + offset;
            long transferred = target.transferFrom(src, position, count);
            assertTrue(transferred >= 0, "transferFrom returned negative");
            assertFalse(count < transferred, count + " < " + transferred);
            ByteBuffer buf = ByteBuffer.allocate((int)transferred);
            target.read(buf, position);
            assertArrayEquals(Arrays.copyOf(bytes, (int)transferred),
                              buf.array(), "arrays unequal");
        }
    }
}