Why does MemoryStream.GetBuffer() always throw?

exception, getbuffer, memorystream, windows

Solution

Here is the documentation for `MemoryStream(byte[])` constructor that you're using. It specifically says:

This constructor does not expose the underlying stream. GetBuffer throws UnauthorizedAccessException.

You should use `MemoryStream(Byte[], Int32, Int32, Boolean, Boolean)` constructor instead, with `publiclyVisible = true`.

Problem

The following code will always throw UnuthorizedAccessException (MemoryStream's internal buffer cannot be accessed.) ``` byte[] buf1 = { 2, 3, 5, 7, 11 }; var ms = new MemoryStream(buf1); byte[] buf2 = ms.GetBuffer(); // exception will be thrown here ``` This is in a plain old console app and I'm running as an admin. I can't imagine a more privileged setting I could give this code. So why can't I get at this buffer? (And if nobody can, what's the point of the GetBuffer method?) The MSDN docs say To create a MemoryStream instance with a publicly visible buffer, use MemoryStream, MemoryStream(array[], Int32, Int32, Boolean, Boolean), or MemoryStream(Int32). Am I not doing that? P.S. I don't want to use ToArray() because that makes a copy.

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