Re: [PATCH v15 19/27] bisect--helper: `bisect_state` & `bisect_head` shell function in C

[Stephan Beyer <s-beyer@gmx.net>]

Hi,

On 10/14/2016 04:14 PM, Pranit Bauva wrote:
> Reimplement the `bisect_state` shell function in C and also add a
> subcommand `--bisect-state` to `git-bisect--helper` to call it from
> git-bisect.sh .
> 
> Using `--bisect-state` subcommand is a temporary measure to port shell
> function to C so as to use the existing test suite. As more functions
> are ported, this subcommand will be retired and will be called by some
> other methods.
> 
> `bisect_head` is called from `bisect_state` thus its not required to
> introduce another subcommand.

Missing comma before "thus", and "it is" (or "it's") instead of "its" :)

> diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
> index 1767916..1481c6d 100644
> --- a/builtin/bisect--helper.c
> +++ b/builtin/bisect--helper.c
> @@ -784,6 +786,79 @@ static int bisect_autostart(struct bisect_terms *terms)
>  	return 0;
>  }
>  
> +static char *bisect_head(void)
> +{
> +	if (is_empty_or_missing_file(git_path_bisect_head()))
> +		return "HEAD";
> +	else
> +		return "BISECT_HEAD";
> +}

This is very shellish.
In C I'd expect something like

static int bisect_head_sha1(unsigned char *sha)
{
	int res;
	if (is_empty_or_missing_file(git_path_bisect_head()))
		res = get_sha1("HEAD", sha);
	else
		res = get_sha1("BISECT_HEAD", sha);

	if (res)
		return error(_("Could not find BISECT_HEAD or HEAD."));

	return 0;
}

> +
> +static int bisect_state(struct bisect_terms *terms, const char **argv,
> +			int argc)
> +{
> +	const char *state = argv[0];
> +
> +	get_terms(terms);
> +	if (check_and_set_terms(terms, state))
> +		return -1;
> +
> +	if (!argc)
> +		die(_("Please call `--bisect-state` with at least one argument"));

I think this check should move to cmd_bisect__helper. There are also the
other argument number checks.

> +
> +	if (argc == 1 && one_of(state, terms->term_good,
> +	    terms->term_bad, "skip", NULL)) {
> +		const char *bisected_head = xstrdup(bisect_head());
> +		const char *hex[1];

Maybe:
		const char *hex;

> +		unsigned char sha1[20];
> +
> +		if (get_sha1(bisected_head, sha1))
> +			die(_("Bad rev input: %s"), bisected_head);

And instead of...

> +		if (bisect_write(state, sha1_to_hex(sha1), terms, 0))
> +			return -1;
> +
> +		*hex = xstrdup(sha1_to_hex(sha1));
> +		if (check_expected_revs(hex, 1))
> +			return -1;

... simply:

		hex = xstrdup(sha1_to_hex(sha1));
		if (set_state(terms, state, hex)) {
			free(hex);
			return -1;
		}
		free(hex);

where:

static int set_state(struct bisect_terms *terms, const char *state,
                                                 const char *hex)
{
	if (bisect_write(state, hex, terms, 0))
		return -1;
	if (check_expected_revs(&hex, 1))
		return -1;
	return 0;
}

> +		return bisect_auto_next(terms, NULL);
> +	}
> +
> +	if ((argc == 2 && !strcmp(state, terms->term_bad)) ||
> +			one_of(state, terms->term_good, "skip", NULL)) {
> +		int i;
> +		struct string_list hex = STRING_LIST_INIT_DUP;
> +
> +		for (i = 1; i < argc; i++) {
> +			unsigned char sha1[20];
> +
> +			if (get_sha1(argv[i], sha1)) {
> +				string_list_clear(&hex, 0);
> +				die(_("Bad rev input: %s"), argv[i]);
> +			}
> +			string_list_append(&hex, sha1_to_hex(sha1));
> +		}
> +		for (i = 0; i < hex.nr; i++) {

... And replace this:

> +			const char **hex_string = (const char **) &hex.items[i].string;
> +			if(bisect_write(state, *hex_string, terms, 0)) {
> +				string_list_clear(&hex, 0);
> +				return -1;
> +			}
> +			if (check_expected_revs(hex_string, 1)) {
> +				string_list_clear(&hex, 0);
> +				return -1;
> +			}

by:

			const char *hex_str = hex.items[i].string;
			if (set_state(terms, state, hex_string)) {
				string_list_clear(&hex, 0);
				return -1;
			}

> +		}
> +		string_list_clear(&hex, 0);
> +		return bisect_auto_next(terms, NULL);
> +	}
> +
> +	if (!strcmp(state, terms->term_bad))
> +		die(_("'git bisect %s' can take only one argument."),
> +		      terms->term_bad);
> +
> +	return -1;
> +}
> +
>  int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
>  {
>  	enum {
> @@ -823,6 +899,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
>  			 N_("verify the next bisection state then find the next bisection state"), BISECT_AUTO_NEXT),
>  		OPT_CMDMODE(0, "bisect-autostart", &cmdmode,
>  			 N_("start the bisection if BISECT_START empty or missing"), BISECT_AUTOSTART),
> +		OPT_CMDMODE(0, "bisect-state", &cmdmode,
> +			 N_("mark the state of ref (or refs)"), BISECT_STATE),

"mark the state of the given revs"

Note that rev != ref

> @@ -902,6 +980,14 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
>  		terms.term_bad = "bad";
>  		res = bisect_autostart(&terms);
>  		break;
> +	case BISECT_STATE:
> +		if (argc == 0)
> +			die(_("--bisect-state requires at least 1 argument"));

"at least one revision"

> diff --git a/git-bisect.sh b/git-bisect.sh
> index cd56551..a9eebbb 100755
> --- a/git-bisect.sh
> +++ b/git-bisect.sh
> @@ -61,44 +51,7 @@ bisect_skip() {
>  		esac
>  		all="$all $revs"
>  	done
> -	eval bisect_state 'skip' $all
[...deleted lines...]
> +	eval git bisect--helper --bisect-state 'skip' $all

I think you don't need "eval" here any longer.

> @@ -184,8 +137,8 @@ exit code \$res from '\$command' is < 0 or >= 128" >&2
>  			state="$TERM_GOOD"
>  		fi
>  
> -		# We have to use a subshell because "bisect_state" can exit.
> -		( bisect_state $state >"$GIT_DIR/BISECT_RUN" )
> +		# We have to use a subshell because "--bisect-state" can exit.
> +		( git bisect--helper --bisect-state $state >"$GIT_DIR/BISECT_RUN" )

The new comment is funny, but you don't need a subshell here any longer.

~Stephan