Consider null terminator when using malloc

[TomaSajt]

I was trying to package this program for Nixpkgs, and used its custom meson builder script, which uses some kind of fortification by default, which catches buffer overflows.

When running the program I got several buffer overflow errors, and with the help of coredumpctl I could trace it back to some string size math. It looks like there wasn't enough space for the null-terminator of the string.

[robiot]

Thanks, looks like I missed that when allocating memory. I will merge this so you can package it for nixpkg!