parse-options: allow omitting option help text

1b68387e02 (builtin/receive-pack.c: use parse_options API, 2016-03-02)
added the options --stateless-rpc, --advertise-refs and
--reject-thin-pack-for-testing with a NULL `help` string; 03831ef7b5
(difftool: implement the functionality in the builtin, 2017-01-19)
similarly added the "helpless" option --prompt.  Presumably this was
done because all four options are hidden and self-explanatory.

They cause a NULL pointer dereference when using the option --help-all
with their respective tool, though.  Handle such options gracefully
instead by turning the NULL pointer into an empty string at the top of
the loop, always printing a newline at the end and passing through the
separating newlines from the help text.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/parse-options.c b/parse-options.c
index 76d2e76b492aff17c09bfad9eaa59bec989350da..e8e076c3a6d9cf30149d833d9ca4f3278aa045ae 100644 (file)
--- a/parse-options.c
+++ b/parse-options.c
@@ -1186,14 +1186,15 @@ static enum parse_opt_result usage_with_options_internal(struct parse_opt_ctx_t
                        continue;
                }
 
-               for (cp = _(opts->help); *cp; cp = np) {
+               for (cp = opts->help ? _(opts->help) : ""; *cp; cp = np) {
                        np = strchrnul(cp, '\n');
-                       usage_padding(outfile, pos);
-                       fprintf(outfile, "%.*s\n", (int)(np - cp), cp);
                        if (*np)
                                np++;
+                       usage_padding(outfile, pos);
+                       fwrite(cp, 1, np - cp, outfile);
                        pos = 0;
                }
+               fputc('\n', outfile);
 
                if (positive_name) {
                        if (find_option_by_long_name(all_opts, positive_name))