public void Seek(long dlibMove, STREAM_SEEK dwOrigin, IntPtr plibNewPosition)
{
SeekOrigin seekOrigin;
switch (dwOrigin)
{
case STREAM_SEEK.STREAM_SEEK_SET:
seekOrigin = SeekOrigin.Begin;
break;
case STREAM_SEEK.STREAM_SEEK_CUR:
seekOrigin = SeekOrigin.Current;
break;
case STREAM_SEEK.STREAM_SEEK_END:
seekOrigin = SeekOrigin.End;
break;
default:
throw new ArgumentOutOfRangeException(nameof(dwOrigin));
}
long newPosition = UnderlyingStream.Seek(dlibMove, seekOrigin);
if (plibNewPosition != IntPtr.Zero)
{
Marshal.WriteInt64(plibNewPosition, 0, newPosition);
}
}
/// <summary>
/// Changes the seek pointer to a new location relative to the beginning of the
/// stream, to the end of the stream, or to the current seek pointer.
/// </summary>
/// <param name="dlibMove">The displacement to add to to dwOrigin</param>
/// <param name="dwOrigin">
/// The origin of the seek. The origin can be the beginning of the file, the
/// current seek pointer, or the end of the file.
/// </param>
/// <param name="plibNewPosition">
/// Upon return, contains the offset of the seek pointer from the beginning of the stream.
/// </param>
public void Seek(long dlibMove, int dwOrigin, IntPtr plibNewPosition)
{
Marshal.WriteInt64(plibNewPosition, stream.Position);
long num = 0L;
switch (dwOrigin)
{
case 0: // STREAM_SEEK_SET
num = dlibMove;
break;
case 1: // STREAM_SEEK_CUR
num = stream.Position + dlibMove;
break;
case 2: // STREAM_SEEK_END
num = stream.Length + dlibMove;
break;
default:
return;
}
if ((num >= 0L) && (num < stream.Length))
{
stream.Position = num;
Marshal.WriteInt64(plibNewPosition, stream.Position);
}
}
void IStream.Seek(long dlibMove, int dwOrigin, IntPtr plibNewPosition)
{
if (plibNewPosition != IntPtr.Zero)
{
Marshal.WriteInt64(plibNewPosition, 0);
}
}
void IStream.Seek(long dlibMove, int dwOrigin, IntPtr plibNewPosition)
{
var origin = (SeekOrigin)dwOrigin;
var pos = Seek(dlibMove, origin);
if (plibNewPosition != IntPtr.Zero)
{
Marshal.WriteInt64(plibNewPosition, pos);
}
}
/// <summary>
/// Writes a specified number of bytes into the stream object starting at the
/// current seek pointer.
/// </summary>
/// <param name="pv">The buffer to write this stream to.</param>
/// <param name="cb">The number of bytes to write to the stream.</param>
/// <param name="pcbWritten">
/// Upon return, contains the actual number of bytes written to the stream object.
/// If the caller sets this pointer to System.IntPtr.Zero, this method does not provide
/// the actual number of bytes written.
/// </param>
public void Write(byte[] pv, int cb, IntPtr pcbWritten)
{
Marshal.WriteInt64(pcbWritten, 0L);
stream.Write(pv, 0, cb);
Marshal.WriteInt64(pcbWritten, (long)cb);
}
/// <summary>
/// Reads a specified number of bytes from the stream object into memory starting
/// at the current seek pointer.
/// </summary>
/// <param name="pv">Upon return, contains the data read from the stream.</param>
/// <param name="cb">The number of bytes to read from the stream object.</param>
/// <param name="pcbRead">
/// A pointer to a ULONG variable that receives the actual number of bytes read
/// from the stream object.
/// </param>
public void Read(byte[] pv, int cb, IntPtr pcbRead)
{
Marshal.WriteInt64(pcbRead, (long)stream.Read(pv, 0, cb));
}
