X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Fopt%2Fusage.c;h=eedaae7eb821d0dab8114de49222b14496887aa0;hp=b7381bc7378c6673c742d6dc23b0c42f211e8265;hb=cdc32f6d35066fe264a228fe20aa75729e41726e;hpb=be6a5cdadeef4995cc935f2d2443f45f542ed125

diff --git a/ccan/opt/usage.c b/ccan/opt/usage.c
index b7381bc7..eedaae7e 100644
--- a/ccan/opt/usage.c
+++ b/ccan/opt/usage.c
@@ -28,6 +28,17 @@ char *opt_usage(const char *argv0, const char *extra)
 	unsigned int i, num, len;
 	char *ret, *p;
 
+	if (!extra) {
+		extra = "";
+		for (i = 0; i < opt_count; i++) {
+			if (opt_table[i].cb == (void *)opt_usage_and_exit
+			    && opt_table[i].arg) {
+				extra = opt_table[i].arg;
+				break;
+			}
+		}
+	}
+
 	/* An overestimate of our length. */
 	len = strlen("Usage: %s ") + strlen(argv0)
 		+ strlen("[-%.*s]") + opt_num_short + 1