c# GzipStream decompress stream only if it is really packed

Question

C++ / C#

In general, the question is not obvious at first glance.

What we have: We have

an inputStream .
We know that it is possibly gzipped. And perhaps not.

What is required:

It is required to read this stream, decompressing if necessary.
If you just wrap it in a GzipStream, it will crash with the error "The magic number in GZip header is not correct".

What's the catch:

You can't just subtract the stream into byte[], and then play with this array, as there are severe speed limits.
Does anyone have any suggestions how to do this?

Answer 1

Offhand: make a wrapper stream that will check magic and then pass or not pass through GZipStream.

Answer 2

RFC 1952

Answer 3

Etssamoe, the bottom line is that even if the magic matches, there is a chance that there is never a gzip inside.