feat(users/Profpatsch/arglib): use exec_helpers for rust

Change-Id: I3056385eb11e45ae13456f4c47052651ba5fb62f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2496
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>

users/Profpatsch/arglib/default.nix

@@ -5,28 +5,30 @@ let
     rust = depot.users.Profpatsch.writers.rustSimpleLib {
       name = "arglib-netencode";
       dependencies = [
+        depot.users.Profpatsch.execline.exec-helpers
         depot.users.Profpatsch.netencode.netencode-rs
       ];
     } ''
       extern crate netencode;
+      extern crate exec_helpers;
 
       use netencode::{T};
       use std::os::unix::ffi::OsStrExt;
 
-      pub fn arglib_netencode(env: Option<&std::ffi::OsStr>) -> Result<T, String> {
+      pub fn arglib_netencode(prog_name: &str, env: Option<&std::ffi::OsStr>) -> T {
           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())),
+              None => exec_helpers::die_user_error(prog_name, 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),
+                      true => t,
-                      false => Err(format!("there was some unparsed bytes remaining: {:?}", remainder))
+                      false => exec_helpers::die_environment_problem(prog_name, format!("arglib: there was some unparsed bytes remaining: {:?}", remainder))
                   },
-                  Err(err) => Err(format!("parsing error: {:?}", err))
+                  Err(err) => exec_helpers::die_environment_problem(prog_name, format!("arglib parsing error: {:?}", err))
               }
           }
       }

users/Profpatsch/netencode/netencode-mustache.rs

@@ -37,7 +37,7 @@ fn netencode_to_mustache_data_dwim(t: T) -> Data {
 
 pub fn from_stdin() -> () {
     let data = netencode_to_mustache_data_dwim(
-        arglib_netencode::arglib_netencode(Some(std::ffi::OsStr::new("TEMPLATE_DATA"))).unwrap()
+        arglib_netencode::arglib_netencode("netencode-mustache", Some(std::ffi::OsStr::new("TEMPLATE_DATA")))
     );
     let mut stdin = String::new();
     std::io::stdin().read_to_string(&mut stdin).unwrap();

users/Profpatsch/read-http.rs

@@ -21,14 +21,14 @@ enum What {
 // The keys are text, but can be lists of text iff headers appear multiple times, so beware.
 fn main() -> std::io::Result<()> {
 
-    let what : What = match arglib_netencode::arglib_netencode(None).unwrap() {
+    let what : What = match arglib_netencode::arglib_netencode("read-http", None) {
         T::Record(rec) => match rec.get("what") {
             Some(T::Text(t)) => match t.as_str() {
                 "request" => What::Request,
                 "response" => What::Response,
-                _ => die_user_error("read-http arglib", "`what` should be either t:request or t:response"),
+                _ => die_user_error("read-http", "`what` should be either t:request or t:response"),
             },
-            Some(o) => die_user_error("read-http arglib", format!("expected a record of text, got {:#?}", o)),
+            Some(o) => die_user_error("read-http", format!("expected a record of text, got {:#?}", o)),
             None => {
                 eprintln!("read-http arglib: no `what` given, defaulting to Response");
                 What::Response