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  1. JDK
  2. JDK-7178109

ByteBuffer does not retain its Endian order when getting a read-only copy

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: P4
    • Resolution: Not an Issue
    • Affects Version/s: 6u31
    • Fix Version/s: None
    • Component/s: core-libs
    • Labels:
    • Subcomponent:
    • CPU:
      x86
    • OS:
      linux

      Description

      FULL PRODUCT VERSION :
      $ java -version
      java version "1.6.0_24"
      OpenJDK Runtime Environment (IcedTea6 1.11.1) (6b24-1.11.1-4ubuntu3)
      OpenJDK 64-Bit Server VM (build 20.0-b12, mixed mode)

      ADDITIONAL OS VERSION INFORMATION :
      Linux 3.2.0-24-generic #39-Ubuntu SMP Mon May 21 16:52:17 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

      A DESCRIPTION OF THE PROBLEM :
      the ByteBuffer returned from ByteBuffer.asReadOnlyBuffer does not retain its order() attribute.

      workaround: calling order(ByteOrder) on the resulting ByteBuffer

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      see the source code for the test case.

      basically, the two buffers should have produced the same int value.

      IntBuffer buf1 = channel.map(FileChannel.MapMode.READ_ONLY, 0, 4).order(ByteOrder.LITTLE_ENDIAN).asIntBuffer();
      IntBuffer buf2 = channel.map(FileChannel.MapMode.READ_ONLY, 0, 4).order(ByteOrder.LITTLE_ENDIAN).asReadOnlyBuffer().asIntBuffer();


      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      expected:
      255
      255
      255
      ACTUAL -
      255
      -16777216
      255

      REPRODUCIBILITY :
      This bug can be reproduced always.

      ---------- BEGIN SOURCE ----------
      import java.io.DataOutputStream;
      import java.io.File;
      import java.io.FileOutputStream;
      import java.io.IOException;
      import java.io.RandomAccessFile;
      import java.nio.ByteOrder;
      import java.nio.IntBuffer;
      import java.nio.channels.FileChannel;

      /** Shows that a buffer doesn't retain its Endian property when copied into a read-only buffer
       *
       * @author Arnon Klein
       *
       */
      public class ReadonlyBufferBug {

      /**
      * @param args
      * @throws IOException
      */
      public static void main(String[] args) throws IOException {
      File f = File.createTempFile("readonly", "bug");
      f.deleteOnExit();
      DataOutputStream d = new DataOutputStream(new FileOutputStream(f));
      d.write(new byte[] {-1,0,0,0});
      d.close();
      FileChannel channel = new RandomAccessFile(f.getAbsolutePath(), "rw").getChannel();
      IntBuffer buf1 = channel.map(FileChannel.MapMode.READ_ONLY, 0, 4).order(ByteOrder.LITTLE_ENDIAN).asIntBuffer();
      IntBuffer buf2 = channel.map(FileChannel.MapMode.READ_ONLY, 0, 4).order(ByteOrder.LITTLE_ENDIAN).asReadOnlyBuffer().asIntBuffer();
      IntBuffer buf3 = channel.map(FileChannel.MapMode.READ_ONLY, 0, 4).asReadOnlyBuffer().order(ByteOrder.LITTLE_ENDIAN).asIntBuffer();
      System.out.println(buf1.get());
      System.out.println(buf2.get());
      System.out.println(buf3.get());
      }

      }
      ---------- END SOURCE ----------

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              Assignee:
              alanb Alan Bateman
              Reporter:
              webbuggrp Webbug Group
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                Updated:
                Resolved:
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