list-objects-filter-options: support --no-filter

Teach opt_parse_list_objects_filter() to take --no-filter
option and to free the contents of struct filter_options.
This command line argument will be automatically inherited
by commands using OPT_PARSE_LIST_OBJECTS_FILTER(); this
includes pack-objects.
Signed-off-by: NJeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/git-pack-objects.txt

@@ -242,6 +242,9 @@ So does `git bundle` (see linkgit:git-bundle[1]) when it creates a bundle.
 	the resulting packfile.  See linkgit:git-rev-list[1] for valid
 	`<filter-spec>` forms.
 
+--no-filter::
+	Turns off any previous `--filter=` argument.
+
 --missing=<missing-action>::
 	A debug option to help with future "partial clone" development.
 	This option specifies how missing objects are handled.

list-objects-filter-options.c

@@ -74,8 +74,19 @@ int opt_parse_list_objects_filter(const struct option *opt,
 {
 	struct list_objects_filter_options *filter_options = opt->value;
 
-	assert(arg);
-	assert(!unset);
+	if (unset || !arg) {
+		list_objects_filter_release(filter_options);
+		return 0;
+	}
 
 	return parse_list_objects_filter(filter_options, arg);
 }
+
+void list_objects_filter_release(
+	struct list_objects_filter_options *filter_options)
+{
+	free(filter_options->filter_spec);
+	free(filter_options->sparse_oid_value);
+	free(filter_options->sparse_path_value);
+	memset(filter_options, 0, sizeof(*filter_options));
+}

list-objects-filter-options.h

@@ -52,7 +52,10 @@ int opt_parse_list_objects_filter(const struct option *opt,
 
 #define OPT_PARSE_LIST_OBJECTS_FILTER(fo) \
 	{ OPTION_CALLBACK, 0, CL_ARG__FILTER, fo, N_("args"), \
-	  N_("object filtering"), PARSE_OPT_NONEG, \
+	  N_("object filtering"), 0, \
 	  opt_parse_list_objects_filter }
 
+void list_objects_filter_release(
+	struct list_objects_filter_options *filter_options);
+
 #endif /* LIST_OBJECTS_FILTER_OPTIONS_H */