retval/Makefile

@@ -1,4 +1,2 @@
-RUSTC = rustc
-
-retval: retval.rs
-	$(RUSTC) $(RUSTCFLAGS) -o retval retval.rs
+retval: retval.c
+	$(CC) -o retval retval.c

retval/retval.c

@@ -3,22 +3,21 @@
 #include <stdlib.h> /* strtol(3) */
 #include <sysexits.h> /* EX_USAGE */
 
-int usage(char *s){
-	fprintf(stderr, "Usage: %s [status]\n", s == NULL ? "retval" : s);
-	return EX_USAGE;
-}
+static char *program_name = "retval";
 
 int main(int argc, char *argv[]){
+	unsigned int s;
 
-	switch(argc){
-		case 2: { unsigned int s;
-			errno = 0;
-			s = strtol(argv[1], &argv[1], 10);
-			if(*argv[1] != '\0' || errno != 0){
-				return usage(argv[0]);
-			}
-			return s;
-		}
-		default: return usage(argv[0]);
+	if(argc < 2)
+		goto usage;
+
+	errno = 0;
+	s = strtol(argv[1], &argv[1], 10);
+	if(*argv[1] != '\0' || errno != 0){
+usage:		fprintf(stderr, "Usage: %s [status]\n",
+			argv[0] == NULL ? program_name : argv[0]);
+		return EX_USAGE;
 	}
+
+	return s;
 }

retval/retval.rs

@@ -1,18 +0,0 @@
-use std::{env::args, process::ExitCode};
-
-fn usage(s: &str) -> ExitCode {
-    eprintln!("Usage: {} [status]", s);
-    ExitCode::from(64 /* NetBSD sysexits(3) EX_USAGE */)
-}
-
-fn main() -> ExitCode {
-    let argv = args().collect::<Vec<String>>();
-
-    match argv.len() {
-        2 => match argv[1].parse::<u8>() {
-            Ok(e) => ExitCode::from(e),
-            _ => usage(&argv[0]),
-        },
-        _ => usage(&argv[0]),
-    }
-}