Re: [PATCH 4/7] built-in stash: use the built-in `git add -p` if so configured

[Junio C Hamano <gitster@pobox.com>]

"Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
writes:

> diff --git a/builtin/stash.c b/builtin/stash.c
> index 4e806176b0..2dafd97766 100644
> --- a/builtin/stash.c
> +++ b/builtin/stash.c
> @@ -999,9 +999,9 @@ static int stash_patch(struct stash_info *info, const struct pathspec *ps,
>  {
>  	int ret = 0;
>  	struct child_process cp_read_tree = CHILD_PROCESS_INIT;
> -	struct child_process cp_add_i = CHILD_PROCESS_INIT;
>  	struct child_process cp_diff_tree = CHILD_PROCESS_INIT;
>  	struct index_state istate = { NULL };
> +	char *old_index_env = NULL, *old_repo_index_file;
>  
>  	remove_path(stash_index_path.buf);
>  

Together with the previous step, it makes sense.  Earlier we always
spawned the scripted version.  Now we first give control to the C
code and allow it to punt to the scripted version unless it is told
to take control with USE_BUILTIN.

> @@ -1015,16 +1015,19 @@ static int stash_patch(struct stash_info *info, const struct pathspec *ps,
>  	}
>  
>  	/* Find out what the user wants. */
> -	cp_add_i.git_cmd = 1;
> -	argv_array_pushl(&cp_add_i.args, "add--interactive", "--patch=stash",
> -			 "--", NULL);
> -	add_pathspecs(&cp_add_i.args, ps);
> -	argv_array_pushf(&cp_add_i.env_array, "GIT_INDEX_FILE=%s",
> -			 stash_index_path.buf);
> -	if (run_command(&cp_add_i)) {
> -		ret = -1;
> -		goto done;
> -	}
> +	old_repo_index_file = the_repository->index_file;
> +	the_repository->index_file = stash_index_path.buf;
> +	old_index_env = xstrdup_or_null(getenv(INDEX_ENVIRONMENT));
> +	setenv(INDEX_ENVIRONMENT, the_repository->index_file, 1);
> +
> +	ret = run_add_interactive(NULL, "--patch=stash", ps);
> +
> +	the_repository->index_file = old_repo_index_file;
> +	if (old_index_env && *old_index_env)
> +		setenv(INDEX_ENVIRONMENT, old_index_env, 1);
> +	else
> +		unsetenv(INDEX_ENVIRONMENT);
> +	FREE_AND_NULL(old_index_env);

OK.  I suspect that, as we move more stuff that used to be an
external call with one-shot environment assignments like this to an
internall call, we'd see patterns of "save away the state of this
and that environment variables, then replace them with these values"
paired with "now restore the state of those environment variables".

We might eventually want to add a helper for doing so easily, which
may make the caller look like

	extern void save_environment(struct saved_env *, ...);

	struct saved_env env;
	save_environment(&env, 
			INDEX_ENVIRONMENT, the_repository->index_file,
			NULL /* end of "VAR, val" tuples */);

	ret = run_add_interactive(NULL, "--patch=stash", ps);

        restore_environment(&env);

It might (or might not) be premature to introduce such a helper at
this stage in the series, though.

Thanks.