fix(cli): report non-UTF-8 arguments instead of panicking (#2207)

* fix(cli): report non-UTF-8 arguments instead of panicking

* fix(cli): avoid echoing malformed arguments

---------

Co-authored-by: Ogulcan Celik <ogulcancelik@gmail.com>

src/main.rs

@@ -464,8 +464,28 @@ fn exit_if_nested_disabled(config: &config::Config) {
     }
 }
 
+fn args_as_utf8<I>(args: I) -> Result<Vec<String>, String>
+where
+    I: IntoIterator<Item = std::ffi::OsString>,
+{
+    args.into_iter()
+        .enumerate()
+        .map(|(index, arg)| {
+            arg.into_string()
+                .map_err(|_| format!("argument {index} is not valid UTF-8"))
+        })
+        .collect()
+}
+
 fn main() -> io::Result<()> {
-    let raw_args: Vec<String> = std::env::args().collect();
+    let raw_args: Vec<String> = match args_as_utf8(std::env::args_os()) {
+        Ok(args) => args,
+        Err(err) => {
+            eprintln!("error: {err}");
+            eprintln!("run 'herdr --help' for usage");
+            std::process::exit(2);
+        }
+    };
     let args = match session::configure_from_args(&raw_args) {
         Ok(args) => args,
         Err(err) => {
@@ -905,4 +925,38 @@ mod tests {
             .iter()
             .all(|message| !message.starts_with("herdr:")));
     }
+
+    #[cfg(unix)]
+    fn invalid_utf8_arg() -> std::ffi::OsString {
+        use std::os::unix::ffi::OsStringExt;
+        std::ffi::OsString::from_vec(vec![0xff])
+    }
+
+    #[cfg(windows)]
+    fn invalid_utf8_arg() -> std::ffi::OsString {
+        use std::os::windows::ffi::OsStringExt;
+        std::ffi::OsString::from_wide(&[0xd800])
+    }
+
+    #[test]
+    fn args_as_utf8_passes_through_valid_arguments() {
+        let args = ["herdr", "pane", "get", "pane-1"].map(std::ffi::OsString::from);
+        assert_eq!(
+            args_as_utf8(args).unwrap(),
+            ["herdr", "pane", "get", "pane-1"]
+        );
+    }
+
+    #[test]
+    fn args_as_utf8_reports_the_offending_argument_instead_of_panicking() {
+        let args = vec![
+            std::ffi::OsString::from("herdr"),
+            std::ffi::OsString::from("pane"),
+            invalid_utf8_arg(),
+        ];
+        assert_eq!(
+            args_as_utf8(args).unwrap_err(),
+            "argument 2 is not valid UTF-8"
+        );
+    }
 }