3204N/A

3204N/A

3204N/Aimport java.io.*;

3204N/Aimport java.nio.ByteBuffer;

3204N/Aimport java.nio.channels.*;

3471N/Aimport java.nio.file.Files;

3204N/Aimport static java.nio.file.StandardOpenOption.*;

3204N/A

3204N/Apublic class LargeFileAvailable {

3204N/A public static void main(String args[]) throws Exception {

5758N/A // Create a temporary file in the current directory.

5758N/A // Use it to check if we have 7G available for

5758N/A // a large sparse file test. As a fallback use whatever

5758N/A // space is available, so the test can proceed.

5758N/A File file = File.createTempFile("largefile", null, new File("."));

5758N/A long spaceavailable = file.getUsableSpace();

5758N/A long filesize = Math.min(spaceavailable, 7405576182L);

5758N/A if (spaceavailable == 0L) {

5758N/A // A full disk is considered fatal.

5758N/A throw new RuntimeException("No space available for temp file.");

5758N/A }

5758N/A

5758N/A createLargeFile(filesize, file);

5758N/A

3204N/A try (FileInputStream fis = new FileInputStream(file)) {

5758N/A if (file.length() != filesize) {

5758N/A throw new RuntimeException("unexpected file size = "

5758N/A + file.length());

3204N/A }

3204N/A

5758N/A long bigSkip = Math.min(filesize/2, 3110608882L);

5758N/A long remaining = filesize;

3204N/A remaining -= skipBytes(fis, bigSkip, remaining);

3204N/A remaining -= skipBytes(fis, 10L, remaining);

3204N/A remaining -= skipBytes(fis, bigSkip, remaining);

3204N/A if (fis.available() != (int) remaining) {

5758N/A throw new RuntimeException("available() returns "

5758N/A + fis.available() + " but expected " + remaining);

3204N/A }

3204N/A } finally {

3204N/A file.delete();

3204N/A }

3204N/A }

3204N/A

3204N/A // Skip toSkip number of bytes and expect that the available() method

3204N/A // returns avail number of bytes.

3204N/A private static long skipBytes(InputStream is, long toSkip, long avail)

3204N/A throws IOException {

3204N/A long skip = is.skip(toSkip);

3204N/A if (skip != toSkip) {

5758N/A throw new RuntimeException("skip() returns " + skip

5758N/A + " but expected " + toSkip);

3204N/A }

3204N/A long remaining = avail - skip;

3204N/A int expected = remaining >= Integer.MAX_VALUE

3204N/A ? Integer.MAX_VALUE

3204N/A : (int) remaining;

3204N/A

5758N/A System.out.println("Skipped " + skip + " bytes "

5758N/A + " available() returns " + expected +

3204N/A " remaining=" + remaining);

3204N/A if (is.available() != expected) {

5758N/A throw new RuntimeException("available() returns "

5758N/A + is.available() + " but expected " + expected);

3204N/A }

3204N/A return skip;

3204N/A }

3204N/A

5758N/A private static void createLargeFile(long filesize,

5758N/A File file) throws Exception {

5758N/A // Recreate a large file as a sparse file if possible

5758N/A Files.delete(file.toPath());

5758N/A

3204N/A try (FileChannel fc =

5758N/A FileChannel.open(file.toPath(),

5758N/A CREATE_NEW, WRITE, SPARSE)) {

3204N/A ByteBuffer bb = ByteBuffer.allocate(1).put((byte)1);

3204N/A bb.rewind();

5758N/A int rc = fc.write(bb, filesize - 1);

5758N/A

3204N/A if (rc != 1) {

5758N/A throw new RuntimeException("Failed to write 1 byte"

5758N/A + " to the large file");

3204N/A }

3204N/A }

5758N/A return;

3204N/A }

3204N/A}