Base 256 encoded numbers

[reynir]

Some tar implementations use base-256 encoded numbers when they are out of range of the octal representation, for example for file sizes greater than 8GB. I think it may be worth supporting in the reader, but for writing I would not implement it and use PAX instead.

Some resources I found:

https://www.gnu.org/software/tar/manual/html_node/Extensions.html

golang/go#12594

https://busybox.busybox.narkive.com/wxISE34V/let-tar-extract-files-8g