Verify/Validate GZip

Question

Hello all.

There's a nasty bug in the forums disallowing me from replying to my own thread:

https://learn.microsoft.com/en-us/answers/questions/1299741/gzip-detection?page=1&orderby=Helpful&comment=answer-1265950

However, to perform a thorough validation of the entire Gzip file, is this method wise?

Using MyGZipStream As New Compression.GZipStream(MyImportStream, Compression.CompressionMode.Decompress, False)
    Try
        MyGZipStream.CopyTo(MyExportStream)
        Return True
    Catch Exception As Exception
        Return False
    End Try
End Using

I'd prefer to not have MyExportStream to be faster, just force GZipStream to read it to validate, and send the output to NULL, or there is any better way to verify a Gzip file?

Answer 1

Hi Peter Volz,

Here is a snippet for you to check if it solves your problem.

using (var myGZipStream = new Compression.GZipStream(MyImportStream, Compression.CompressionMode.Decompress))
{
    try
    {
        byte[] _buffer = new byte[4096]; //Here, we read decompressed data, but don't write it to an output stream
        while (myGZipStream.Read(_buffer, 0, _buffer.Length) > 0) {}
        return true; //If it gets this far, your Gzip is valid.
    }
    catch (Exception)
    {
        return false; //If an exception occurs, it indicates that your Gzip is invalid
    }
}

Using myGZipStream As New GZipStream(MyImportStream, Compression.CompressionMode.Decompress)
    Try
        Dim buffer As Byte() = New Byte(4096) {} 'Here, we read decompressed data, but don't write it to an output stream
        While myGZipStream.Read(buffer, 0, buffer.Length) > 0
        End While
        Return True 'If it gets this far, your Gzip is valid.
    Catch
        Return False 'If an exception occurs, it indicates that your Gzip is invalid
    End Try
End Using

Regards,

Answer 2

Hi Peter Volz,

Here is a snippet for you to check if it solves your problem.

using (var myGZipStream = new Compression.GZipStream(MyImportStream, Compression.CompressionMode.Decompress))
{
    try
    {
        byte[] _buffer = new byte[4096]; //Here, we read decompressed data, but don't write it to an output stream
        while (myGZipStream.Read(_buffer, 0, _buffer.Length) > 0) {}
        return true; //If it gets this far, your Gzip is valid.
    }
    catch (Exception)
    {
        return false; //If an exception occurs, it indicates that your Gzip is invalid
    }
}

Regards,