tvl-depot/users/Profpatsch/arglib/default.nix
Profpatsch 5d44df3af6 refactor(users/Profpatsch): move arglib_netencode into its own lib
arglib is the simple idea of passing structured data via a
conventional environment variable instead of implementing an optparser
for every little tool.

Pop the envvar, decode the contents, return the contents.

Change-Id: Ie44148293a58aae9a0a613895176227d43b491bb
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2449
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>
2021-01-31 11:10:00 +00:00

40 lines
1.2 KiB
Nix

{ depot, pkgs, lib, ... }:
let
netencode = {
rust = depot.users.Profpatsch.writers.rustSimpleLib {
name = "arglib-netencode";
dependencies = [
depot.users.Profpatsch.netencode.netencode-rs
];
} ''
extern crate netencode;
use netencode::{T};
use std::os::unix::ffi::OsStrExt;
pub fn arglib_netencode(env: Option<&std::ffi::OsStr>) -> Result<T, String> {
let env = match env {
None => std::ffi::OsStr::from_bytes("ARGLIB_NETENCODE".as_bytes()),
Some(a) => a
};
match std::env::var_os(env) {
None => Err(format!("could not read args, envvar {} not set", env.to_string_lossy())),
// TODO: good error handling for the different parser errors
Some(soup) => match netencode::parse::t_t(soup.as_bytes()) {
Ok((remainder, t)) => match remainder.is_empty() {
true => Ok(t),
false => Err(format!("there was some unparsed bytes remaining: {:?}", remainder))
},
Err(err) => Err(format!("parsing error: {:?}", err))
}
}
}
'';
};
in {
inherit
netencode
;
}