iptables: allow for help-less extensions

This is for extensions that do not take any options, and which
subsequently do not offer any help text either.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>

1 files changed, 31 insertions, 0 deletions

diff --git a/xshared.c b/xshared.c
new file mode 100644
index 00000000..21b5b2cb
--- /dev/null
+++ b/xshared.c
@@ -0,0 +1,31 @@
+#include <stdio.h>
+#include <xtables.h>
+#include "xshared.h"
+
+/*
+ * Print out any special helps. A user might like to be able to add a --help
+ * to the commandline, and see expected results. So we call help for all
+ * specified matches and targets.
+ */
+void print_extension_helps(const struct xtables_target *t,
+    const struct xtables_rule_match *m)
+{
+	for (; t != NULL; t = t->next) {
+		if (t->used) {
+			printf("\n");
+			if (t->help == NULL)
+				printf("%s does not take any options\n",
+				       t->name);
+			else
+				t->help();
+		}
+	}
+	for (; m != NULL; m = m->next) {
+		printf("\n");
+		if (m->match->help == NULL)
+			printf("%s does not take any options\n",
+			       m->match->name);
+		else
+			m->match->help();
+	}
+}