bisect--helper: reimplement `bisect_visualize()` shell function in C

Reimplement the `bisect_visualize()` shell function
in C and also add `--bisect-visualize` subcommand to
`git bisect--helper` to call it from git-bisect.sh.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Mentored-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/bisect--helper.c

@@ -30,6 +30,7 @@ static const char * const git_bisect_helper_usage[] = {
 	N_("git bisect--helper --bisect-state (good|old) [<rev>...]"),
 	N_("git bisect--helper --bisect-replay <filename>"),
 	N_("git bisect--helper --bisect-skip [(<rev>|<range>)...]"),
+	N_("git bisect--helper --bisect-visualize"),
 	NULL
 };
 
@@ -1036,6 +1037,44 @@ static enum bisect_error bisect_skip(struct bisect_terms *terms, const char **ar
 	return res;
 }
 
+static int bisect_visualize(struct bisect_terms *terms, const char **argv, int argc)
+{
+	struct strvec args = STRVEC_INIT;
+	int flags = RUN_COMMAND_NO_STDIN, res = 0;
+	struct strbuf sb = STRBUF_INIT;
+
+	if (bisect_next_check(terms, NULL) != 0)
+		return BISECT_FAILED;
+
+	if (!argc) {
+		if ((getenv("DISPLAY") || getenv("SESSIONNAME") || getenv("MSYSTEM") ||
+		     getenv("SECURITYSESSIONID")) && exists_in_PATH("gitk")) {
+			strvec_push(&args, "gitk");
+		} else {
+			strvec_push(&args, "log");
+			flags |= RUN_GIT_CMD;
+		}
+	} else {
+		if (argv[0][0] == '-') {
+			strvec_push(&args, "log");
+			flags |= RUN_GIT_CMD;
+		} else if (strcmp(argv[0], "tig") && !starts_with(argv[0], "git"))
+			flags |= RUN_GIT_CMD;
+
+		strvec_pushv(&args, argv);
+	}
+
+	strvec_pushl(&args, "--bisect", "--", NULL);
+
+	strbuf_read_file(&sb, git_path_bisect_names(), 0);
+	sq_dequote_to_strvec(sb.buf, &args);
+	strbuf_release(&sb);
+
+	res = run_command_v_opt(args.v, flags);
+	strvec_clear(&args);
+	return res;
+}
+
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
 	enum {
@@ -1048,7 +1087,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 		BISECT_STATE,
 		BISECT_LOG,
 		BISECT_REPLAY,
-		BISECT_SKIP
+		BISECT_SKIP,
+		BISECT_VISUALIZE,
 	} cmdmode = 0;
 	int res = 0, nolog = 0;
 	struct option options[] = {
@@ -1070,6 +1110,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 			 N_("replay the bisection process from the given file"), BISECT_REPLAY),
 		OPT_CMDMODE(0, "bisect-skip", &cmdmode,
 			 N_("skip some commits for checkout"), BISECT_SKIP),
+		OPT_CMDMODE(0, "bisect-visualize", &cmdmode,
+			 N_("visualize the bisection"), BISECT_VISUALIZE),
 		OPT_BOOL(0, "no-log", &nolog,
 			 N_("no log for BISECT_WRITE")),
 		OPT_END()
@@ -1131,6 +1173,10 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 		get_terms(&terms);
 		res = bisect_skip(&terms, argv, argc);
 		break;
+	case BISECT_VISUALIZE:
+		get_terms(&terms);
+		res = bisect_visualize(&terms, argv, argc);
+		break;
 	default:
 		BUG("unknown subcommand %d", cmdmode);
 	}

git-bisect.sh

@@ -39,29 +39,6 @@ _x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"
 TERM_BAD=bad
 TERM_GOOD=good
 
-bisect_visualize() {
-	git bisect--helper --bisect-next-check $TERM_GOOD $TERM_BAD fail || exit
-
-	if test $# = 0
-	then
-		if test -n "${DISPLAY+set}${SESSIONNAME+set}${MSYSTEM+set}${SECURITYSESSIONID+set}" &&
-			type gitk >/dev/null 2>&1
-		then
-			set gitk
-		else
-			set git log
-		fi
-	else
-		case "$1" in
-		git*|tig) ;;
-		-*)	set git log "$@" ;;
-		*)	set git "$@" ;;
-		esac
-	fi
-
-	eval '"$@"' --bisect -- $(cat "$GIT_DIR/BISECT_NAMES")
-}
-
 bisect_run () {
 	git bisect--helper --bisect-next-check $TERM_GOOD $TERM_BAD fail || exit
 
@@ -152,7 +129,7 @@ case "$#" in
 		# Not sure we want "next" at the UI level anymore.
 		git bisect--helper --bisect-next "$@" || exit ;;
 	visualize|view)
-		bisect_visualize "$@" ;;
+		git bisect--helper --bisect-visualize "$@" || exit;;
 	reset)
 		git bisect--helper --bisect-reset "$@" ;;
 	replay)