how to get position and length of unzipped gzipstream in c#?

Question

i'm trying to read .gz files using binary reader by first unzipping with gzipstream, and then creating a new binary reader with the gzipstream. however, when i try to use the BaseStream.Position and BaseStream.Length of BinaryReader (to know when i'm at the end of my file), i get a NotSupportedException, checking the doc for these fields in GZipStream Class shows:

Length
This property is not supported and always throws a NotSupportedException.(Overrides Stream.Length.)

Position
This property is not supported and always throws a NotSupportedException.(Overrides Stream.Position.)

so my question is how can i know when i'm at the end of my file when reading a decompressed GZipStream using BinaryReader? thanks

here is my code:

Stream stream = new MemoryStream(textAsset.bytes);
GZipStream zippedStream = new GZipStream(stream, CompressionMode.Decompress);
using (BinaryReader reader = new BinaryReader(zippedStream))
    while(reader.BaseStream.Position != reader.BaseStream.Length)
    {
        //do stuff with BinaryReader
    }

the above throws: NotSupportedException: Operation is not supported. System.IO.Compression.DeflateStream.get_Position()

due to the BaseStream.Position call in the while()

Answer 1

You can copy your zippedStream to MemoryStream instance, that can be read fully using ToArray function. That is the easiest solution I can think of.

Stream stream = new MemoryStream(textAsset.bytes);
byte[] result;
using (GZipStream zippedStream = new GZipStream(stream, CompressionMode.Decompress))
{
    using (MemoryStream reader = new MemoryStream())
    {
        zippedStream.CopyTo(reader);
        result = reader.ToArray();
    }
}

Alternatively if you want to read stream in chunks

using (GZipStream zippedStream = new GZipStream(stream, CompressionMode.Decompress))
{
    byte[] buffer = new byte[16 * 1024];
    int read;
    while ((read = zippedStream.Read(buffer, 0, buffer.Length)) > 0)
    {
        // do work
    }
}