provide -h option. Deny regular user execution

src/extra-tools/66-nuke.c

@@ -11,14 +11,60 @@
  * This file may not be copied, modified, propagated, or distributed
  * except according to the terms contained in the LICENSE file./
  *
- * This file is a strict copy of s6-echo.c file
- * coming from skarnet software at https://skarnet.org/software/s6-portable-utils.
+ * This file is a modified copy of s6-linux-init-nuke.c file
+ * coming from skarnet software at https://skarnet.org/software/s6-linux-init.
  * All credits goes to Laurent Bercot <ska-remove-this-if-you-are-not-a-bot@skarnet.org>
  * */
 
 #include <signal.h>
+#include <unistd.h>
 
-int main (void)
+#include <oblibs/log.h>
+
+#include <skalibs/sgetopt.h>
+
+#define USAGE "66-nuke"
+
+static inline void info_help (void)
+{
+    DEFAULT_MSG = 0 ;
+
+    static char const *help =
+"\n"
+"options :\n"
+"   -h: print this help\n"
+;
+
+    log_info(USAGE,"\n",help) ;
+}
+
+int main (int argc, char const *const *argv)
 {
-  return kill(-1, SIGKILL) < 0 ;
+
+    {
+        subgetopt_t l = SUBGETOPT_ZERO ;
+
+        for (;;)
+        {
+            int opt = subgetopt_r(argc,argv, "h", &l) ;
+
+            if (opt == -1) break ;
+            switch (opt)
+            {
+                case 'h' :
+
+                    info_help();
+                    return 0 ;
+
+                default :
+
+                    log_usage(USAGE) ;
+            }
+        }
+    }
+
+    if (getuid())
+        log_die(LOG_EXIT_SYS,"You must be root to use this program") ;
+
+    return kill(-1, SIGKILL) < 0 ;
 }