opt: add opt_log_stderr_exit helper, and opt_usage NULL option.

[ccan] / ccan / opt / usage.c

diff --git a/ccan/opt/usage.c b/ccan/opt/usage.c
index b7381bc7378c6673c742d6dc23b0c42f211e8265..eedaae7eb821d0dab8114de49222b14496887aa0 100644 (file)
--- 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