DeviceIoControl function for querying SCSI device

[Lorenzo Bergamini]

Hello everyone,

I am working on a project where I need to read a specific SCSI disk sector to retrieve some information about the device.

I have a complete code working on C++/Windows, but I wanted to make a Java version both because I am more familiar with Java GUI management

and because I need portability on OSx and I would like to avoid reimplementing everything from scratch.

This said, I started using the JNA library only recently and I think I need your help now :)

What I did so far is defining the SCSI_PASS_THROUGH_DIRECT structure as follows

public class SCSI_PASS_THROUGH_DIRECT extends Structure
{

    public short Length;
    public byte ScsiStatus;
    public byte PathId;
    public byte TargetId;
    public byte Lun;
    public byte CdbLength;
    public byte SenseInfoLength;
    public byte DataIn;
    public short DataTransferLength;
    public short TimeOutValue;
    public Pointer DataBuffer;
    public short SenseInfoOffset;
    public byte[] Cdb = new byte[16];
    @Override
    protected List getFieldOrder()
    {
        return Arrays.asList(new String[] {"Length", "ScsiStatus", "PathId", "TargetId", "Lun", "CdbLength", "SenseInfoLength", "DataIn" ,
        "DataTransferLength", "TimeOutValue", "DataBuffer", "SenseInfoOffset", "Cdb"});
    }
   
}

According to what reported on msdn site and what I did in my C sample, (almost) everything is compliant. The bigger change I had to introduce is to replace the LONG values of DataTransferLength, TimeOutValue and SenseInfoOffset specified in the MSDN with short, otherwise I was getting an error 1306 ERROR_REVISION_MISMATCH when running the code. I think it was some mapping error and I am not sure the solution I did is good, but in any case for now I am getting a more "familiar" error 87 - INCORRECT PARAMETER.

The second structure I am using is


The following code is what I have for the moment

public static void main(String[] args)
    {
       
        StringBuffer devicePath = new StringBuffer("\\\\.\\I:");
        WinNT.HANDLE hVolume = openDiskHandleString(devicePath.toString(), 0);

        Kernel32 lib = (Kernel32) Native.loadLibrary("kernel32", Kernel32.class);
       
        SCSI_PASS_THROUGH_DIRECT sptd = new SCSI_PASS_THROUGH_DIRECT();
        int IOCTL_SCSI_PASS_THROUGH_DIRECT = 0x0004d014;
        SCSI_result_buffer scsi_result = new SCSI_result_buffer();
        System.out.println("Structure size: " + sptd.size());
        Pointer pointer = sptd.getPointer();
        int sector_to_read = 0x500;
        sptd.Length = (byte)sptd.size();
        sptd.ScsiStatus = 0;
        sptd.PathId = 0;
        sptd.TargetId = 0;
        sptd.Lun = 0;
        sptd.CdbLength = 10;       //lenght of the SCSI Cdb we are using
        sptd.SenseInfoLength = 0;
        sptd.DataIn = 1;           //1 means read data from the device
        sptd.DataTransferLength = 512;
        sptd.TimeOutValue = 10;        
        sptd.SenseInfoOffset = (short)sptd.size();
        sptd.Cdb[0] = 0x28;        //0x28 is the command code for a read operation
        sptd.Cdb[1] = 0;  
        sptd.Cdb[5] = (byte)(sector_to_read % 256);           //LSB byte
        sector_to_read = (int) sector_to_read / 256;              
        sptd.Cdb[4] = (byte)(sector_to_read % 256);          
        sector_to_read = (int) sector_to_read / 256;
        sptd.Cdb[3] = (byte)(sector_to_read % 256);
        sector_to_read = (int) sector_to_read / 256;
        sptd.Cdb[2] = (byte)(sector_to_read % 256);
        sptd.Cdb[7] = 0;
        sptd.Cdb[8] = 01;
        IntByReference dwBytesReturned = new IntByReference(0);
        Pointer test = sptd.getPointer();
       
        System.out.println("Pointer: " + test.dump(0, 12));
       
        boolean control_code = lib.DeviceIoControl(hVolume, IOCTL_SCSI_PASS_THROUGH_DIRECT, test, sptd.size(), scsi_result.getPointer(), 512, dwBytesReturned, Pointer.NULL);
        if (control_code)
        {
            System.out.println("Data OK");
        }
        else
            System.out.println("DeviceIOControl error: " + lib.GetLastError());
       
       
        System.out.println("Returned bytes: " + dwBytesReturned.getValue());
       
        for (int i = 0; i < dwBytesReturned.getValue(); i++)
        {
          System.out.printf(" %02x", scsi_result.data[i]);        
        }


    }
   
        private static WinNT.HANDLE openDiskHandleString(String path, int access) {
        WinNT.HANDLE HandleToDevice;
        int shareMode = WinNT.FILE_SHARE_READ | WinNT.FILE_SHARE_WRITE;
 
       
        HandleToDevice = Kernel32.INSTANCE.CreateFile(
                "\\\\.\\I:",
                WinNT.GENERIC_READ|WinNT.GENERIC_WRITE,
                shareMode,
                null,
                WinNT.OPEN_EXISTING,
                0,
                null);
       
          if (HandleToDevice != WinNT.INVALID_HANDLE_VALUE)
          {
             System.out.println("OK");
             return HandleToDevice;
          }
          else
          {
              System.out.println("Error");
              return null;
          }
    }

So, as I said, I am able to open the handle to the device without any problem, but the execution of the code results in a "DeviceIOControl Error: 87", which, as I said, is an incorrect parameter.
I am pretty sure that the problem is in how I pass the Pointer, but I was not able to find a suitable description of how Pointers should be used in this situation.
Is there anyone able to help me either by suggesting a solution, or by pointing me to some extensive example on how to use Java Pointers?

Thank you very much for your help.

Lorenzo

[L Will Ahonen]

Hi,

Does the size of the struct match on C and Java? If you replaced longs with shorts, it probably doesn't. You might want to use NativeLong here.

Cheers,

Will

...

[Timothy Wall]

You’re using “short” where you should be using ULONG, NativeLong, or just plain int (safe on w32 since NativeLong on windows is always 32 bits).

This will result in a structure that is too small, and likely data corruption in everything after the “DataIn” field.