more cleaning

retval/retval.c

@@ -0,0 +1,25 @@
+#include <ctype.h> /* isdigit(3) */
+#include <sysexits.h> /* EX_USAGE */
+#include <unistd.h> /* write(2) */
+#include "libio.h" /* fdprint(3), parse_uint(3) */
+
+static char *program_name = "retval";
+
+int main(int argc, char *argv[]){
+	unsigned int s;
+
+	if(argc < 2){
+usage:		write(2, "Usage: ", 7);
+		fdprint(2, argv[0] == NULL ? program_name : argv[0]);
+		write(2, " [status]\n", 10);
+		return EX_USAGE;
+	}
+
+	for(s = 0; argv[1][s] != '\0'; ++s)
+		if(!isdigit(argv[1][s]))
+			goto usage;
+
+	s = parse_uint(argv[1]);
+
+	return s;
+}