0N/A

0N/A

0N/Aimport java.io.*;

0N/Aimport java.nio.ByteBuffer;

0N/Aimport java.nio.channels.*;

0N/Aimport java.nio.file.Files;

0N/Aimport static java.nio.file.StandardOpenOption.*;

0N/A

0N/Apublic class LargeFileAvailable {

0N/A public static void main(String args[]) throws Exception {

0N/A // Create a temporary file in the current directory.

0N/A // Use it to check if we have 7G available for

0N/A // a large sparse file test. As a fallback use whatever

0N/A // space is available, so the test can proceed.

0N/A File file = File.createTempFile("largefile", null, new File("."));

0N/A long spaceavailable = file.getUsableSpace();

0N/A long filesize = Math.min(spaceavailable, 7405576182L);

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

0N/A // A full disk is considered fatal.

0N/A throw new RuntimeException("No space available for temp file.");

0N/A }

0N/A

0N/A createLargeFile(filesize, file);

0N/A

0N/A try (FileInputStream fis = new FileInputStream(file)) {

0N/A if (file.length() != filesize) {

0N/A throw new RuntimeException("unexpected file size = "

0N/A + file.length());

0N/A }

0N/A

0N/A long bigSkip = Math.min(filesize/2, 3110608882L);

0N/A long remaining = filesize;

0N/A remaining -= skipBytes(fis, bigSkip, remaining);

0N/A remaining -= skipBytes(fis, 10L, remaining);

0N/A remaining -= skipBytes(fis, bigSkip, remaining);

0N/A if (fis.available() != (int) remaining) {

0N/A throw new RuntimeException("available() returns "

0N/A + fis.available() + " but expected " + remaining);

0N/A }

0N/A } finally {

0N/A file.delete();

0N/A }

0N/A }

0N/A

0N/A // Skip toSkip number of bytes and expect that the available() method

0N/A // returns avail number of bytes.

0N/A private static long skipBytes(InputStream is, long toSkip, long avail)

0N/A throws IOException {

0N/A long skip = is.skip(toSkip);

0N/A if (skip != toSkip) {

0N/A throw new RuntimeException("skip() returns " + skip

0N/A + " but expected " + toSkip);

0N/A }

0N/A long remaining = avail - skip;

0N/A int expected = remaining >= Integer.MAX_VALUE

0N/A ? Integer.MAX_VALUE

0N/A : (int) remaining;

0N/A

0N/A System.out.println("Skipped " + skip + " bytes "

0N/A + " available() returns " + expected +

0N/A " remaining=" + remaining);

0N/A if (is.available() != expected) {

0N/A throw new RuntimeException("available() returns "

0N/A + is.available() + " but expected " + expected);

0N/A }

0N/A return skip;

0N/A }

0N/A

0N/A private static void createLargeFile(long filesize,

0N/A File file) throws Exception {

0N/A // Recreate a large file as a sparse file if possible

0N/A Files.delete(file.toPath());

938N/A

938N/A try (FileChannel fc =

938N/A FileChannel.open(file.toPath(),

938N/A CREATE_NEW, WRITE, SPARSE)) {

938N/A ByteBuffer bb = ByteBuffer.allocate(1).put((byte)1);

939N/A bb.rewind();

939N/A int rc = fc.write(bb, filesize - 1);

938N/A

938N/A if (rc != 1) {

939N/A throw new RuntimeException("Failed to write 1 byte"

939N/A + " to the large file");

938N/A }

938N/A }

938N/A return;

938N/A }

938N/A}

938N/A