command line: support -f in Hash Bang Null Hack.

* txr.c (txr_main): In processing the -f option, if there is
already an input source, but its name exactly matches the
argument of the -f option, then ignore the -f and its option
intead of terminating with a diagnostic. This allows the user
to use -f in the Null Hack to achieve the usual trick of
allowing the script to take options passed through to the
interpreter.

* txr.1: Documented.

1 files changed, 5 insertions, 3 deletions

diff --git a/txr.c b/txr.c
index 584ec159..be77ca1c 100644
--- a/txr.c
+++ b/txr.c
@@ -839,13 +839,15 @@ int txr_main(int argc, char **argv)
         parse_stream = make_string_byte_input_stream(specstring);
         break;
       case 'f':
+        spec_file = arg;
         if (parse_stream) {
+          if (equal(spec_file, spec_file_str))
+            break;
           format(std_error,
-                 lit("~a: -f ~a: input file has already been established\n"),
-                 prog_string, spec_file, nao);
+                 lit("~a: -f ~a: input source ~a has already been established\n"),
+                 prog_string, arg, spec_file_str, nao);
           return EXIT_FAILURE;
         }
-        spec_file = arg;
         if (wcscmp(c_str(spec_file), L"-") != 0) {
           open_txr_file(spec_file, &txr_lisp_p, &spec_file_str, &parse_stream);
           simulate_setuid_setgid(parse_stream);