"Cole Helbling" <cole.e.helbling@outlook.com> writes:

>> @@ -1319,17 +1319,52 @@ fn set_argument(cfg: &mut Config, name: &str, value: Option<&str>) -> argument::
>>          }
>>          "vhost-net" => cfg.vhost_net = true,
>>          "tap-fd" => {
>> -            cfg.tap_fd.push(
>> -                value
>> -                    .unwrap()
>> -                    .parse()
>> -                    .map_err(|_| argument::Error::InvalidValue {
>> -                        value: value.unwrap().to_owned(),
>> -                        expected: String::from(
>> -                            "this value for `tap-fd` must be an unsigned integer",
>> -                        ),
>> -                    })?,
>> -            );
>> +            let mut components = value.unwrap().split(',');
>> +
>> +            let fd: RawDescriptor = components
>> +                .next()
>> +                .and_then(|x| x.parse().ok())
>> +                .ok_or_else(|| argument::Error::InvalidValue {
>> +                    value: value.unwrap().to_owned(),
>> +                    expected: String::from("this value for `tap-fd` must be an unsigned integer"),
>> +                })?;
>> +
>> +            let mut mac = None;
>> +            for c in components {
>> +                let mut kv = c.splitn(2, '=');
>> +                let (kind, value) = match (kv.next(), kv.next()) {
>> +                    (Some(kind), Some(value)) => (kind, value),
>> +                    _ => {
>> +                        return Err(argument::Error::InvalidValue {
>> +                            value: c.to_owned(),
>> +                            expected: String::from("option must be of the form `kind=value`"),
>> +                        })
>> +                    }
>> +                };
>> +                match kind {
>> +                    "mac" => {
>> +                        mac = Some(value.parse().map_err(|_| argument::Error::InvalidValue {
>> +                            value: value.to_owned(),
>> +                            expected: String::from(
>> +                                "`mac` needs to be in the form \"XX:XX:XX:XX:XX:XX\"",
>> +                            ),
>> +                        })?)
>> +                    }
>> +                    _ => {
>> +                        return Err(argument::Error::InvalidValue {
>> +                            value: kind.to_owned(),
>> +                            expected: String::from("unrecognized option"),
>> +                        })
>> +                    }
>> +                }
>> +            }
>> +            if cfg.tap_fd.contains_key(&fd) {
>> +                return Err(argument::Error::TooManyArguments(format!(
>
> Is there a better Error variant for this? `TooManyArguments` seems not-
> completely-accurate when specifying an already-in-use FD.

Here are all the variants.  Do you think there's a better one?

https://chromium.googlesource.com/chromiumos/platform/crosvm/+/f35d2c43ff19520855cffee761dc8899c5a439a1/src/argument.rs#49

The only other one I can see that might be applicable would be
InvalidValue...