Re: [PATCH v16 Part II 5/8] bisect--helper: `bisect_next_check` shell function in C

Reimplement `bisect_next_check` shell function in C and add
`bisect-next-check` subcommand to `git bisect--helper` to call it from
git-bisect.sh .

`bisect_voc` shell function is no longer useful now and is replaced by
using a char *[] of "new|bad" and "good|old" values.

Using `--bisect-next-check` 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 but its implementation will
be called by some other methods.

Helped-by: Stephan Beyer [off-list ref]
Mentored-by: Lars Schneider [off-list ref]
Mentored-by: Christian Couder [off-list ref]
Signed-off-by: Pranit Bauva <redacted>
---
 builtin/bisect--helper.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++-
 git-bisect.sh            | 60 +++----------------------------
 2 files changed, 94 insertions(+), 57 deletions(-)

diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index 65abf8a70c6d9..0f9c3e63821b8 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c

@@ -6,6 +6,7 @@
 #include "dir.h"
 #include "argv-array.h"
 #include "run-command.h"
+#include "prompt.h"
 
 static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
 static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")

@@ -21,6 +22,7 @@ static const char * const git_bisect_helper_usage[] = {
 	N_("git bisect--helper --bisect-reset [<commit>]"),
 	N_("git bisect--helper --bisect-write <state> <revision> <good_term> <bad_term> [<nolog>]"),
 	N_("git bisect--helper --bisect-check-and-set-terms <command> <good_term> <bad_term>"),
+	N_("git bisect--helper --bisect-next-check [<term>] <good_term> <bad_term>"),
 	NULL
 };
 

@@ -44,6 +46,11 @@ static void set_terms(struct bisect_terms *terms, const char *bad,
 	terms->term_bad = xstrdup(bad);
 }
 
+static const char *voc[] = {
+	"bad|new",
+	"good|old"
+};
+

 /*
  * Check whether the string `term` belongs to the set of strings
  * included in the variable arguments.

@@ -264,6 +271,79 @@ static int check_and_set_terms(struct bisect_terms *terms, const char *cmd)
 	return 0;
 }
 
+static int mark_good(const char *refname, const struct object_id *oid,
+		     int flag, void *cb_data)
+{
+	int *m_good = (int *)cb_data;
+	*m_good = 0;
+	return 1;
+}
+
+static int bisect_next_check(const struct bisect_terms *terms,
+			     const char *current_term)
+{
+	int missing_good = 1, missing_bad = 1, retval = 0;
+	const char *bad_ref = xstrfmt("refs/bisect/%s", terms->term_bad);
+	const char *good_glob = xstrfmt("%s-*", terms->term_good);
+
+	if (ref_exists(bad_ref))
+		missing_bad = 0;
+
+	for_each_glob_ref_in(mark_good, good_glob, "refs/bisect/",
+			     (void *) &missing_good);
+
+	if (!missing_good && !missing_bad)
+		goto finish;
+
+	if (!current_term)
+		goto fail;
+
+	if (missing_good && !missing_bad && current_term &&
+	    !strcmp(current_term, terms->term_good)) {
+		char *yesno;
+		/*
+		 * have bad (or new) but not good (or old). We could bisect
+		 * although this is less optimum.
+		 */
+		fprintf(stderr, _("Warning: bisecting only with a %s commit\n"),
+			terms->term_bad);
+		if (!isatty(0))
+			goto finish;
+		/*
+		 * TRANSLATORS: Make sure to include [Y] and [n] in your
+		 * translation. The program will only accept English input
+		 * at this point.
+		 */
+		yesno = git_prompt(_("Are you sure [Y/n]? "), PROMPT_ECHO);
+		if (starts_with(yesno, "N") || starts_with(yesno, "n"))
+			goto fail;
+
+		goto finish;
+	}
+	if (!is_empty_or_missing_file(git_path_bisect_start())) {
+		error(_("You need to give me at least one %s and "
+			"%s revision. You can use \"git bisect %s\" "
+			"and \"git bisect %s\" for that.\n"),
+			voc[0], voc[1], voc[0], voc[1]);