[PATCH 2/9] setpriv: prepare option parsing logic for additional opts

[Patrick Steinhardt]

The current option parsing logic of setpriv only supports the case where
we want to execute a sub-program and have at most one argument. Refactor
handling of options to solve these shortcomings to make it easy to
support `setpriv --dump`, which does not accept any additional
arguments, as well as the case where additional options are passed to
setpriv. This is done by handling `argc` ourselves, throwing an error
when no program is specified, as well as introducing an enum for the
different option bitmasks.
---
 util-linux/setpriv.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/util-linux/setpriv.c b/util-linux/setpriv.c
index 686ad45d5..24e577131 100644
--- a/util-linux/setpriv.c
+++ b/util-linux/setpriv.c
@@ -51,6 +51,10 @@
 #define PR_SET_NO_NEW_PRIVS 38
 #endif
 
+enum {
+	OPT_NNP = (1 << 0),
+};
+
 int setpriv_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int setpriv_main(int argc UNUSED_PARAM, char **argv)
 {
@@ -60,15 +64,20 @@ int setpriv_main(int argc UNUSED_PARAM, char **argv)
 		;
 	int opts;
 
-	opt_complementary = "-1";
+	opt_complementary = "";
 	applet_long_options = setpriv_longopts;
 	opts = getopt32(argv, "+");
 
-	if (opts) {
+	argc -= optind;
+	argv += optind;
+
+	if (!argc)
+		bb_error_msg_and_die("no program specified");
+
+	if (opts & OPT_NNP) {
 		if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0))
 			bb_simple_perror_msg_and_die("prctl: NO_NEW_PRIVS");
 	}
 
-	argv += optind;
 	BB_EXECVP_or_die(argv);
 }
-- 
2.13.2