parse-options: fix segmentation fault when a required value is missing

p->argc represent the number of arguments that have not been parsed yet,
_including_ the one we are currently parsing. If it is not greater than
one then there is no more argument.

Signed-off-by: Olivier Marin <dkr@freesurf.fr>
Acked-by: Pierre Habouzit <madcoder@debian.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

parse-options.c

@@ -22,7 +22,7 @@ static int get_arg(struct parse_opt_ctx_t *p, const struct option *opt,
 		p->opt = NULL;
 	} else if (p->argc == 1 && (opt->flags & PARSE_OPT_LASTARG_DEFAULT)) {
 		*arg = (const char *)opt->defval;
-	} else if (p->argc) {
+	} else if (p->argc > 1) {
 		p->argc--;
 		*arg = *++p->argv;
 	} else

t/t0040-parse-options.sh

@@ -78,6 +78,13 @@ test_expect_success 'long options' '
 	test_cmp expect output
 '
 
+test_expect_success 'missing required value' '
+	test-parse-options -s;
+	test $? = 129 &&
+	test-parse-options --string;
+	test $? = 129
+'
+
 cat > expect << EOF
 boolean: 1
 integer: 13