From: Junio C Hamano <gitster@pobox.com>
Date: Wed, 29 May 2024 17:28:05 GMT
Subject: Re: [PATCH 03/19] global: convert intentionally-leaking config strings to consts
Message-ID: <xmqqle3sy1cq.fsf@gitster.g>
In-Reply-To: <8f3decbb762916a536ec7a8d319c5903bd8f30c1.1716983704.git.ps@pks.im>

Patrick Steinhardt <ps@pks.im> writes:

> There are multiple cases where we intentionally leak config strings:
>
>   - `struct gpg_format` is used to track programs that can be used for
>     signing commits, either via gpg(1), gpgsm(1) or ssh-keygen(1). The
>     user can override the commands via several config variables. As the
>     array is populated once, only, and will never be free'd, it is fine
>     to treat the program as a quasi-constant.
>
>   - `struct ll_merge_driver` is used to track merge drivers. Same as
>     with the GPG format, these drivers are populated once and then
>     reused. Its data is never free'd, either.
>
>   - `struct userdiff_funcname` and `struct userdiff_driver` can be
>     configured via `diff.<driver>.*` to add additional drivers. Again,
>     these have a global lifetime and are never free'd.
>
> All of these are intentionally kept alive and never free'd. Let's mark
> the respective fields as `const char *` and cast away the constness when
> assigning those values.

It is not unclear where the linkage between "not freed" and "must be
const" comes from.  What am I missing?

Thanks.