Stream.Length throws NotSupportedException

Question

I am getting a error when attempting stream.Length on a Stream object sent into my WCF method.

Unhandled Exception!  Error ID: 0  Error Code: Unknown  Is Warning: False  Type: System.NotSupportedException  Stack:    at System.ServiceModel.Dispatcher.StreamFormatter.MessageBodyStream.get_Length() 

How do you get the length of the stream? any examples?

Answer 1

Stream.Length only works on Stream implementations where seeking is available. You can usually check to see if Stream.CanSeek is true. Many streams, since they're being streamed, are of a nature where it's impossible to know the length in advance.

If you must know the length, you may need to actually buffer the entire stream, loading it into memory in advance.

Answer 2

This is what I do:

// Return the length of a stream that does not have a usable Length property public static long GetStreamLength(Stream stream) {     long originalPosition = 0;     long totalBytesRead = 0;      if (stream.CanSeek)     {         originalPosition = stream.Position;         stream.Position = 0;     }      try     {         byte[] readBuffer = new byte[4096];         int bytesRead;          while ((bytesRead = stream.Read(readBuffer, 0, 4096)) > 0)         {             totalBytesRead += bytesRead;         }      }     finally     {         if (stream.CanSeek)         {             stream.Position = originalPosition;         }     }      return totalBytesRead; }