[PATCH 15/26] bisect--helper: `bisect_autostart` shell function in C

["Pranit Bauva via GitGitGadget" <gitgitgadget@gmail.com>]

From: Pranit Bauva <pranit.bauva@gmail.com>

Reimplement the `bisect_autostart()` shell function in C and add the
C implementation from `bisect_next()` which was previously left
uncovered. Also add a subcommand `--bisect-autostart` to
`git bisect--helper` be called from `bisect_state()` from
git-bisect.sh .

Using `--bisect-autostart` 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 `bisect_state()`.

Mentored-by: Lars Schneider <larsxschneider@gmail.com>
Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
---
 builtin/bisect--helper.c | 39 +++++++++++++++++++++++++++++++++++++++
 git-bisect.sh            | 23 +----------------------
 2 files changed, 40 insertions(+), 22 deletions(-)

diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index 1a525faf27..61c3cc517a 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -30,6 +30,7 @@ static const char * const git_bisect_helper_usage[] = {
 					     "[--no-checkout] [<bad> [<good>...]] [--] [<paths>...]"),
 	N_("git bisect--helper --bisect-next"),
 	N_("git bisect--helper --bisect-auto-next"),
+	N_("git bisect--helper --bisect-autostart"),
 	NULL
 };
 
@@ -56,6 +57,8 @@ static void set_terms(struct bisect_terms *terms, const char *bad,
 static const char *vocab_bad = "bad|new";
 static const char *vocab_good = "good|old";
 
+static int bisect_autostart(struct bisect_terms *terms);
+
 /*
  * Check whether the string `term` belongs to the set of strings
  * included in the variable arguments.
@@ -530,6 +533,7 @@ static int bisect_next(struct bisect_terms *terms, const char *prefix)
 {
 	int res, no_checkout;
 
+	bisect_autostart(terms);
 	if (bisect_next_check(terms, terms->term_good))
 		return -1;
 
@@ -788,6 +792,32 @@ static int bisect_start(struct bisect_terms *terms, int no_checkout,
 	return res;
 }
 
+static int bisect_autostart(struct bisect_terms *terms)
+{
+	if (is_empty_or_missing_file(git_path_bisect_start())) {
+		const char *yesno;
+		const char *argv[] = {NULL};
+		fprintf(stderr, _("You need to start by \"git bisect "
+				  "start\"\n"));
+
+		if (!isatty(STDIN_FILENO))
+			return 1;
+
+		/*
+		 * TRANSLATORS: Make sure to include [Y] and [n] in your
+		 * translation. The program will only accept English input
+		 * at this point.
+		 */
+		yesno = git_prompt(_("Do you want me to do it for you "
+				     "[Y/n]? "), PROMPT_ECHO);
+		if (starts_with(yesno, _("n")) || starts_with(yesno, _("N")))
+			return 1;
+
+		return bisect_start(terms, 0, argv, 0);
+	}
+	return 0;
+}
+
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
 	enum {
@@ -801,6 +831,7 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 		BISECT_START,
 		BISECT_NEXT,
 		BISECT_AUTO_NEXT,
+		BISECT_AUTOSTART,
 	} cmdmode = 0;
 	int no_checkout = 0, res = 0, nolog = 0;
 	struct option options[] = {
@@ -824,6 +855,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 			 N_("find the next bisection commit"), BISECT_NEXT),
 		OPT_CMDMODE(0, "bisect-auto-next", &cmdmode,
 			 N_("verify the next bisection state then checkout the next bisection commit"), BISECT_AUTO_NEXT),
+		OPT_CMDMODE(0, "bisect-autostart", &cmdmode,
+			 N_("start the bisection if BISECT_START is empty or missing"), BISECT_AUTOSTART),
 		OPT_BOOL(0, "no-checkout", &no_checkout,
 			 N_("update BISECT_HEAD instead of checking out the current commit")),
 		OPT_BOOL(0, "no-log", &nolog,
@@ -890,6 +923,12 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 		get_terms(&terms);
 		res = bisect_auto_next(&terms, prefix);
 		break;
+	case BISECT_AUTOSTART:
+		if (argc)
+			return error(_("--bisect-autostart requires 0 arguments"));
+		set_terms(&terms, "bad", "good");
+		res = bisect_autostart(&terms);
+		break;
 	default:
 		return error("BUG: unknown subcommand '%d'", cmdmode);
 	}
diff --git a/git-bisect.sh b/git-bisect.sh
index fec527e1ef..97bb15b38f 100755
--- a/git-bisect.sh
+++ b/git-bisect.sh
@@ -49,27 +49,6 @@ bisect_head()
 	fi
 }
 
-bisect_autostart() {
-	test -s "$GIT_DIR/BISECT_START" || {
-		gettextln "You need to start by \"git bisect start\"" >&2
-		if test -t 0
-		then
-			# TRANSLATORS: Make sure to include [Y] and [n] in your
-			# translation. The program will only accept English input
-			# at this point.
-			gettext "Do you want me to do it for you [Y/n]? " >&2
-			read yesno
-			case "$yesno" in
-			[Nn]*)
-				exit ;;
-			esac
-			git bisect--helper --bisect-start
-		else
-			exit 1
-		fi
-	}
-}
-
 bisect_skip() {
 	all=''
 	for arg in "$@"
@@ -86,7 +65,7 @@ bisect_skip() {
 }
 
 bisect_state() {
-	bisect_autostart
+	git bisect--helper --bisect-autostart
 	state=$1
 	git bisect--helper --check-and-set-terms $state $TERM_GOOD $TERM_BAD || exit
 	get_terms
-- 
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