Re: [PATCH v1] config: add '--sources' option to print the source of a config value

> On Fri, Feb 05, 2016 at 09:42:30AM +0100, larsxschneider@gmail.com wrote:
> 
>> @@ -538,6 +569,17 @@ int cmd_config(int argc, const char **argv, const char *prefix)
>> 		error("--name-only is only applicable to --list or --get-regexp");
>> 		usage_with_options(builtin_config_usage, builtin_config_options);
>> 	}
>> +
>> +	const int is_query_action = actions & (
>> +		ACTION_GET|ACTION_GET_ALL|ACTION_GET_REGEXP|ACTION_LIST|
>> +		ACTION_GET_COLOR|ACTION_GET_COLORBOOL|ACTION_GET_URLMATCH
>> +	);
>> +
>> +	if (show_sources && !is_query_action) {
>> +		error("--sources is only applicable to --list or --get-* actions");
>> +		usage_with_options(builtin_config_usage, builtin_config_options);
>> +	}
> 
> Hmm. I had originally envisioned this only being used with "--list", but
> I guess it makes sense to say "--sources --get" to show where the value
> for a particular option is coming from.
> 
> The plural "sources" is a little funny there, though, as we list only
> the "last one wins" final value, not all of them (for that, you can use
> "--sources --get-all", which seems handy). I think it would be
> sufficient for the documentation to make this clear (speaking of which,
> this patch needs documentation...).

> 
> Also, I don't think the feature works with --get-color, --get-colorbool,
> or --get-urlmatch (which don't do their output in quite the same way).
> I think it would be fine to simply disallow --sources with those options
> rather than worry about making it work.

>> +/* output to either fp or buf; only one should be non-NULL */
>> +static void show_config_source(struct strbuf *buf, FILE *fp)
>> +{
>> +	const char *fn = current_config_filename();
>> +	if (!fn)
>> +		return;
> 
> I'm not sure returning here is the best idea. We won't have a config
> filename if we are reading from "-c", but if we return early from this
> function, it parses differently than every other line. E.g., with your
> patch, if I do:
> 
>  git config -c foo.bar=true config --sources --list
> 
> I'll get:
> 
>  /home/peff/.gitconfig <tab> user.name=Jeff King
>  /home/peff/.gitconfig <tab> user.email=peff@peff.net
>  ...etc...
>  foo.bar=true
> 
> If somebody is parsing this as a tab-delimited list, then instead of the
> source field for that line being empty, it is missing (and it looks like
> "foo.bar=true" is the source file). I think it would be more friendly to
> consumers of the output to have a blank (i.e., set "fn" to the empty
> string and continue in the function).

> 
>> +
>> +	char term = '\t';
> 
> This declaration comes after the "if" above, but git style doesn't allow
> declaration-after-statement (to support ancient compilers).

> 
>> +test_expect_success '--sources' '
>> +	>.git/config &&
>> +	>"$HOME"/.gitconfig &&
>> +	INCLUDE_DIR="$HOME/include" &&
>> +	mkdir -p "$INCLUDE_DIR" &&
>> +	cat >"$INCLUDE_DIR"/include.conf <<-EOF &&
>> +		[user]
>> +			include = true
>> +	EOF
>> +	cat >"$HOME"/file.conf <<-EOF &&
>> +		[user]
>> +			custom = true
>> +	EOF
>> +	test_config_global user.global "true" &&
>> +	test_config_global user.override "global" &&
>> +	test_config_global include.path "$INCLUDE_DIR"/include.conf &&
> 
> Here you include the file by its absolute path. I wondered what would
> happen if we used a relative path. E.g.:
> 
>  git config include.path=foo
>  git config -f .git/foo included.config=true
>  git config --sources --list
> 
> which shows it as ".git/foo", because we resolved it by manipulating the
> relative path ".git/config". Whereas including it from ~/.gitconfig will
> show the absolute path, because we use the absolute path to get to
> ~/.gitconfig in the first place.
> 
> I think that's all sane. I don't know if it's worth noting it in the
> documentation or not.

> 
>> +	cat >expect <<-EOF &&
>> +		$HOME/.gitconfig	user.global=true
>> +		$HOME/.gitconfig	user.override=global
>> +		$HOME/.gitconfig	include.path=$INCLUDE_DIR/include.conf
>> +		$INCLUDE_DIR/include.conf	user.include=true
>> +		.git/config	user.local=true
>> +		.git/config	user.override=local
>> +		user.cmdline=true
>> +	EOF
> 
> If the filename has funny characters (e.g., a literal tab), it will be
> quoted here (but not in the --null output below). Worth including in the
> test?

> 
>> +	cat >expect <<-EOF &&
>> +		.git/config	local
>> +	EOF
>> +	git config --sources user.override >output &&
>> +	test_cmp expect output &&
> 
> Good thoroughness in checking the override case.

> 
>> +	cat >expect <<-EOF &&
>> +		a9d9f9e555b5c6f07cbe09d3f06fe3df11e09c08	user.custom=true
>> +	EOF
>> +	blob=$(git hash-object -w "$HOME"/file.conf) &&
>> +	git config --blob=$blob --sources --list >output &&
>> +	test_cmp expect output
> 
> This one was unexpected to me, but I think it makes sense. The option is
> "--sources" and not "--source-filenames", after all. It's probably worth
> mentioning in the documentation.