bisect--helper: `bisect_reset` shell function in C

Reimplement `bisect_reset` shell function in C and add a `--bisect-reset`
subcommand to `git bisect--helper` to call it from git-bisect.sh .

Using `bisect_reset` subcommand is a temporary measure to port shell
functions to C so as to use the existing test suite. As more functions
are ported, this subcommand would be retired but its implementation will
be called by some other method.

Note: --bisect-clean-state subcommand has not been retired as there are
still a function namely `bisect_start()` which still uses this
subcommand.

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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 50 insertions, 1 deletions

diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index 4b5fadcbe1..aa6495dc84 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -3,15 +3,21 @@
 #include "parse-options.h"
 #include "bisect.h"
 #include "refs.h"
+#include "dir.h"
+#include "argv-array.h"
+#include "run-command.h"
 
 static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
 static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")
 static GIT_PATH_FUNC(git_path_bisect_ancestors_ok, "BISECT_ANCESTORS_OK")
+static GIT_PATH_FUNC(git_path_bisect_start, "BISECT_START")
+static GIT_PATH_FUNC(git_path_bisect_head, "BISECT_HEAD")
 
 static const char * const git_bisect_helper_usage[] = {
 	N_("git bisect--helper --next-all [--no-checkout]"),
 	N_("git bisect--helper --write-terms <bad_term> <good_term>"),
 	N_("git bisect--helper --bisect-clean-state"),
+	N_("git bisect--helper --bisect-reset [<commit>]"),
 	NULL
 };
 
@@ -106,13 +112,50 @@ static void check_expected_revs(const char **revs, int rev_nr)
 	}
 }
 
+static int bisect_reset(const char *commit)
+{
+	struct strbuf branch = STRBUF_INIT;
+
+	if (!commit) {
+		if (strbuf_read_file(&branch, git_path_bisect_start(), 0) < 1) {
+			printf(_("We are not bisecting.\n"));
+			return 0;
+		}
+		strbuf_rtrim(&branch);
+	} else {
+		struct object_id oid;
+
+		if (get_oid_commit(commit, &oid))
+			return error(_("'%s' is not a valid commit"), commit);
+		strbuf_addstr(&branch, commit);
+	}
+
+	if (!file_exists(git_path_bisect_head())) {
+		struct argv_array argv = ARGV_ARRAY_INIT;
+
+		argv_array_pushl(&argv, "checkout", branch.buf, "--", NULL);
+		if (run_command_v_opt(argv.argv, RUN_GIT_CMD)) {
+			strbuf_release(&branch);
+			argv_array_clear(&argv);
+			return error(_("could not check out original"
+				       " HEAD '%s'. Try 'git bisect"
+				       "reset <commit>'."), branch.buf);
+		}
+		argv_array_clear(&argv);
+	}
+
+	strbuf_release(&branch);
+	return bisect_clean_state();
+}
+
 int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 {
 	enum {
 		NEXT_ALL = 1,
 		WRITE_TERMS,
 		BISECT_CLEAN_STATE,
-		CHECK_EXPECTED_REVS
+		CHECK_EXPECTED_REVS,
+		BISECT_RESET
 	} cmdmode = 0;
 	int no_checkout = 0;
 	struct option options[] = {
@@ -124,6 +167,8 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 			 N_("cleanup the bisection state"), BISECT_CLEAN_STATE),
 		OPT_CMDMODE(0, "check-expected-revs", &cmdmode,
 			 N_("check for expected revs"), CHECK_EXPECTED_REVS),
+		OPT_CMDMODE(0, "bisect-reset", &cmdmode,
+			 N_("reset the bisection state"), BISECT_RESET),
 		OPT_BOOL(0, "no-checkout", &no_checkout,
 			 N_("update BISECT_HEAD instead of checking out the current commit")),
 		OPT_END()
@@ -149,6 +194,10 @@ int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
 	case CHECK_EXPECTED_REVS:
 		check_expected_revs(argv, argc);
 		return 0;
+	case BISECT_RESET:
+		if (argc > 1)
+			return error(_("--bisect-reset requires either no argument or a commit"));
+		return !!bisect_reset(argc ? argv[0] : NULL);
 	default:
 		return error("BUG: unknown subcommand '%d'", cmdmode);
 	}