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

> "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.