Subject: Re: bug#33878: zcat vs zcat -f -- different output
From: Paul Eggert <[email-masked]>
To: Namikaze Minato <[email-masked]>, [email-masked]
Date: Wed, 26 Dec 2018 10:03:57 -0800
List-Id: <debbugs-submit.debbugs.gnu.org>

Namikaze Minato wrote:

> Do you know what could be happening?

When gzip -cdf sees junk input data, it simply copies it to standard output; 
this behavior is documented in the gzip manual (look for --force). Your input 
files have NUL-byte padding at the end, contrary to Internet RFC 1952.

> Do you know how I could try to reproduce the problem on
> non-confidential data for you to be able to debug?

$ (gzip </dev/null; printf '\0') >t.gz
$ gzip -cd <t.gz | od -c
0000000
$ gzip -cdf <t.gz | od -c
0000000  \0
0000001

Though it's not a bug....