keyfork-derive-openpgp: use run-fn style

keyfork-derive-openpgp/src/main.rs

@@ -1,4 +1,4 @@
-use std::{env, str::FromStr};
+use std::{env, str::FromStr, process::ExitCode};
 
 use keyfork_derive_util::{
     request::{DerivationAlgorithm, DerivationRequest},
@@ -97,7 +97,7 @@ fn validate(
     Ok((path, subkey_format, UserID::from(default_userid)))
 }
 
-fn main() -> Result<(), Box<dyn std::error::Error>> {
+fn run() -> Result<(), Box<dyn std::error::Error>> {
     let mut args = env::args();
     let program_name = args.next().expect("program name");
     let args = args.collect::<Vec<_>>();
@@ -130,3 +130,12 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     Ok(())
 }
+
+fn main() -> ExitCode {
+    if let Err(e) = run() {
+        eprintln!("Error: {e}");
+        ExitCode::FAILURE
+    } else {
+        ExitCode::SUCCESS
+    }
+}