public override long Seek(long offset, SeekOrigin origin)
{
if (stream == null)
{
throw new ObjectDisposedException("GMimeStream", "The backing stream has been closed.");
}
if (stream is StreamFilter)
{
if (offset != 0 || origin != SeekOrigin.Begin)
{
throw new NotSupportedException();
}
// offset = 0 is a special case and means reset the streamfilter
((StreamFilter)stream).Reset();
return(0);
}
long ret = -1;
switch (origin)
{
case SeekOrigin.Begin:
if (offset < 0)
{
throw new ArgumentOutOfRangeException();
}
ret = stream.Seek(offset, GMime.SeekWhence.Set);
break;
case SeekOrigin.Current:
ret = stream.Seek(offset, GMime.SeekWhence.Cur);
break;
case SeekOrigin.End:
if (offset > 0)
{
throw new ArgumentOutOfRangeException();
}
ret = stream.Seek(offset, GMime.SeekWhence.End);
break;
}
if (ret == -1)
{
throw new IOException();
}
return(ret);
}
