Fix omdb support-bundles download --output

[papertigers]

I noticed we were unable to save a support bundle when passing an output location.

root@oxz_switch1:~# omdb nexus support-bundles list
note: Nexus URL not specified.  Will pick one from DNS.
note: using DNS server for subnet fd00:1122:3344::/48
note: (if this is not right, use --dns-server to specify an alternate DNS server)
note: using Nexus URL http://[fd00:1122:3344:102::5]:12232
ID                                   TIME_CREATED                   REASON_FOR_CREATION     REASON_FOR_FAILURE STATE  USER_COMMENT
e3adf9b8-f16a-4d89-b8c9-d1de6e888b89 2025-11-12 16:38:21.171665 UTC Created by internal API -                  Active -


root@oxz_switch1:~# omdb nexus support-bundles download -o /root/support-bundle.zip e3adf9b8-f16a-4d89-b8c9-d1de6e888b89
note: Nexus URL not specified.  Will pick one from DNS.
note: using DNS server for subnet fd00:1122:3344::/48
note: (if this is not right, use --dns-server to specify an alternate DNS server)
note: using Nexus URL http://[fd00:1122:3344:102::5]:12232
Error: Invalid argument (os error 22)

I spent some time with DTrace and truss but I couldn't find any calls to open(2) where an actual EINVAL was being returned. After some further inspection it turns out Rust is making up this EINVAL on it's own rather then passing the open flags to the open(2) call.

    fn get_creation_mode(&self) -> io::Result<c_int> {
        match (self.write, self.append) {
            (true, false) => {}
            (false, false) => {
                if self.truncate || self.create || self.create_new {
                    return Err(Error::from_raw_os_error(libc::EINVAL));
                }
            }
            (_, true) => {
                if self.truncate && !self.create_new {
                    return Err(Error::from_raw_os_error(libc::EINVAL));
                }
            }
        }

[wfchandler]

Nice catch, thanks!