Re: [PATCH v2 4/7] config: add --fixed-value option, un-implemented

[Emily Shaffer <emilyshaffer@google.com>]

On Mon, Nov 23, 2020 at 04:05:04PM +0000, Derrick Stolee via GitGitGadget wrote:
> 
> 
> The 'git config' builtin takes a 'value_regex' parameter for several
> actions. This can cause confusion when expecting exact value matches
> instead of regex matches, especially when the input string contains glob
> characters. While callers can escape the patterns themselves, it would
> be more friendly to allow an argument to disable the pattern matching in
> favor of an exact string match.
> 
> Add a new '--fixed-value' option that does not currently change the
> behavior. The implementation will follow for each appropriate action.
> For now, check and test that --fixed-value will abort the command when
> included with an incompatible action or without a 'value_regex'
> argument.
> 
> The name '--fixed-value' was chosen over something simpler like
> '--fixed' because some commands allow regular expressions on the
> key in addition to the value.
> 
> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
> ---
>  Documentation/git-config.txt | 20 +++++++++++++-------
>  builtin/config.c             | 26 ++++++++++++++++++++++++++
>  t/t1300-config.sh            | 23 +++++++++++++++++++++++
>  3 files changed, 62 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/git-config.txt b/Documentation/git-config.txt
> index 7573160f21..d4bb928ea7 100644
> --- a/builtin/config.c
> +++ b/builtin/config.c
> @@ -34,6 +34,7 @@ static int respect_includes_opt = -1;
>  static struct config_options config_options;
>  static int show_origin;
>  static int show_scope;
> +static int fixed_value;
>  
>  #define ACTION_GET (1<<0)
>  #define ACTION_GET_ALL (1<<1)
> @@ -141,6 +142,7 @@ static struct option builtin_config_options[] = {
>  	OPT_BIT(0, "rename-section", &actions, N_("rename section: old-name new-name"), ACTION_RENAME_SECTION),
>  	OPT_BIT(0, "remove-section", &actions, N_("remove a section: name"), ACTION_REMOVE_SECTION),
>  	OPT_BIT('l', "list", &actions, N_("list all"), ACTION_LIST),
> +	OPT_BOOL(0, "fixed-value", &fixed_value, N_("use string equality when matching values")),
I'm not sure how to feel about this phrasing. I wonder if it would be
clearer to say something like 'treat 'value_regex' as a literal string
instead'? Hmmm.

> +	if (fixed_value) {
> +		int allowed_usage = 0;
> +
> +		switch (actions) {
> +		case ACTION_GET:
> +		case ACTION_GET_ALL:
> +		case ACTION_GET_REGEXP:
> +		case ACTION_UNSET:
> +		case ACTION_UNSET_ALL:
> +			allowed_usage = argc > 1 && !!argv[1];
> +			break;
> +
> +		case ACTION_SET_ALL:
> +		case ACTION_REPLACE_ALL:
> +			allowed_usage = argc > 2 && !!argv[2];
> +			break;
> +		}
> +
> +		if (!allowed_usage) {
> +			error(_("--fixed-value only applies with 'value_regex'"));
> +			usage_builtin_config();
> +		}
> +	}
> +

To me this really needs a comment. I think you are checking whether the
value_regex is actually present, and the position of that regex changes
depending on the rest of the arg list... What about something like:

  /* If set, ensure 'value_regex' was provided also */
  if (fixed_value) {
    ...
    /* 'git config --unset-all <key> <value_regex>' */
    case ACTION_UNSET_ALL:
    ...
    /* 'git config --replace-all <key> <new value> <value_regex>' */
    case ACTION_REPLACE_ALL:
    ...

> +test_expect_success 'refuse --fixed-value for incompatible actions' '
> +	git config --file=config dev.null bogus &&
> +
> +	# These modes do not allow --fixed-value at all
> +	test_must_fail git config --file=config --fixed-value --add dev.null bogus &&
> +	test_must_fail git config --file=config --fixed-value --get-urlmatch dev.null bogus &&
> +	test_must_fail git config --file=config --fixed-value --get-urlmatch dev.null bogus &&
> +	test_must_fail git config --file=config --fixed-value --rename-section dev null &&
> +	test_must_fail git config --file=config --fixed-value --remove-section dev &&
> +	test_must_fail git config --file=config --fixed-value --list &&
> +	test_must_fail git config --file=config --fixed-value --get-color dev.null &&
> +	test_must_fail git config --file=config --fixed-value --get-colorbool dev.null &&
> +
> +	# These modes complain when --fixed-value has no value_regex
> +	test_must_fail git config --file=config --fixed-value dev.null bogus &&
> +	test_must_fail git config --file=config --fixed-value --replace-all dev.null bogus &&
> +	test_must_fail git config --file=config --fixed-value --get dev.null &&
> +	test_must_fail git config --file=config --fixed-value --get-all dev.null &&
> +	test_must_fail git config --file=config --fixed-value --get-regexp "dev.*" &&
> +	test_must_fail git config --file=config --fixed-value --unset dev.null &&
> +	test_must_fail git config --file=config --fixed-value --unset-all dev.null
> +'
> +

I'd expect to see a positive test as well, which you could later evolve
into a test to ensure behavior.

 - Emily