Re: [PATCH v3 3/3] config: allow overriding of global and system configuration

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 12, 2021, 17:04 UTC
Message-ID: <xmqq4kgbfn8o.fsf@gitster.g>
In-Reply-To: <af663640ae25a95fa56adf32baf4c2e197f3eea2.1618238567.git.ps@pks.im>

Patrick Steinhardt <ps@pks.im> writes:

Show 8 quoted lines

>  char *git_system_config(void)
>  {
> +	char *system_config = xstrdup_or_null(getenv("GIT_CONFIG_SYSTEM"));
> +	if (system_config) {
> +		if (!strcmp(system_config, "/dev/null"))
> +			FREE_AND_NULL(system_config);
> +		return system_config;
> +	}

I am not sure if returning NULL from this function will always be the same as returning /dev/null on a system with functioning /dev/null. For example, when use_system_config is enabled, builtin/config.c::cmd_config() assigns the NULL returned by this function to given_config_source.file and then calls config.c::config_with_options(), which notices that none of use_stdin, file, or blob member of the config_source exists and falls back to the config_sequence().

So, for the purpose of special casing "/dev/null" textually, the above is not sufficient, I am afraid.

Let's rescind the "/dev/null gets turned into NULL" in the above change for now. If we truly want to cater to an installation where open("/dev/null") fails and emulate, that needs to be done at a much lower layer, but we do not have to go there for the purpose of this series.

Thanks.