builtin/gc.c: replace `git_config()` with `git_config_get_*()` family

Use `git_config_get_*()` family instead of `git_config()` to take advantage of
the config-set API which provides a cleaner control flow.
Signed-off-by: NTanay Abhra <tanayabh@gmail.com>
Reviewed-by: NMatthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin/gc.c

@@ -55,44 +55,33 @@ static void remove_pidfile_on_signal(int signo)
 	raise(signo);
 }
 
-static int gc_config(const char *var, const char *value, void *cb)
+static void gc_config(void)
 {
-	if (!strcmp(var, "gc.packrefs")) {
+	const char *value;
+
+	if (!git_config_get_value("gc.packrefs", &value)) {
 		if (value && !strcmp(value, "notbare"))
 			pack_refs = -1;
 		else
-			pack_refs = git_config_bool(var, value);
-		return 0;
-	}
-	if (!strcmp(var, "gc.aggressivewindow")) {
-		aggressive_window = git_config_int(var, value);
-		return 0;
-	}
-	if (!strcmp(var, "gc.aggressivedepth")) {
-		aggressive_depth = git_config_int(var, value);
-		return 0;
-	}
-	if (!strcmp(var, "gc.auto")) {
-		gc_auto_threshold = git_config_int(var, value);
-		return 0;
-	}
-	if (!strcmp(var, "gc.autopacklimit")) {
-		gc_auto_pack_limit = git_config_int(var, value);
-		return 0;
+			pack_refs = git_config_bool("gc.packrefs", value);
 	}
-	if (!strcmp(var, "gc.autodetach")) {
-		detach_auto = git_config_bool(var, value);
-		return 0;
-	}
-	if (!strcmp(var, "gc.pruneexpire")) {
-		if (value && strcmp(value, "now")) {
+
+	git_config_get_int("gc.aggressivewindow", &aggressive_window);
+	git_config_get_int("gc.aggressivedepth", &aggressive_depth);
+	git_config_get_int("gc.auto", &gc_auto_threshold);
+	git_config_get_int("gc.autopacklimit", &gc_auto_pack_limit);
+	git_config_get_bool("gc.autodetach", &detach_auto);
+
+	if (!git_config_get_string_const("gc.pruneexpire", &prune_expire)) {
+		if (strcmp(prune_expire, "now")) {
 			unsigned long now = approxidate("now");
-			if (approxidate(value) >= now)
-				return error(_("Invalid %s: '%s'"), var, value);
+			if (approxidate(prune_expire) >= now) {
+				git_die_config("gc.pruneexpire", _("Invalid gc.pruneexpire: '%s'"),
+						prune_expire);
+			}
 		}
-		return git_config_string(&prune_expire, var, value);
 	}
-	return git_default_config(var, value, cb);
+	git_config(git_default_config, NULL);
 }
 
 static int too_many_loose_objects(void)
@@ -301,7 +290,7 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 	argv_array_pushl(&prune, "prune", "--expire", NULL );
 	argv_array_pushl(&rerere, "rerere", "gc", NULL);
 
-	git_config(gc_config, NULL);
+	gc_config();
 
 	if (pack_refs < 0)
 		pack_refs = !is_bare_repository();