Determining file extension given a FileStream

c# filestream file-extension
Abdul Samad picture Abdul Samad · Jan 18, 2012 · Viewed 20.8k times · Source

Is there any way to know the type of the FileStream. I have a function that takes a FileStream object and I want to determine the file extension based on that FileStream.

Answer

JaredPar picture JaredPar · Jan 18, 2012

If the stream is really a FileStream then you should be able to do the following

var ext = Path.GetExtension(fileStream.Name);

If it's a plain old Stream though then it's not generally possible to get the extension because a Stream can be created for any stream of bytes. It doesn't have to have a backing file.

Update

As Chris pointed out in the comments there is another SO question which is relevant to this discussion. It's discussing heuristics for determining type of a byte[] which can then be mapped to a probable original signature.

It's by no means foolproof but may be helpful to you.

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