feat(users/Profpatsch/execline/exec_helpers): add args() r/2207

Some programs need an exact amount of arguments, and we want to fail
if they get too many or not enough.

Change-Id: Ic703949f38780718f26118b896e7c7d7aa5553d9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2504
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>

2 files changed, 11 insertions, 1 deletions

diff --git a/users/Profpatsch/execline/exec_helpers.rs b/users/Profpatsch/execline/exec_helpers.rs
index bc4650fbad9a..b9e1f5797386 100644
--- a/users/Profpatsch/execline/exec_helpers.rs
+++ b/users/Profpatsch/execline/exec_helpers.rs
@@ -11,6 +11,16 @@ pub fn no_args(current_prog_name: &str) -> () {
     }
 }
 
+pub fn args(current_prog_name: &str, no_of_positional_args: usize) -> Vec<Vec<u8>> {
+    let mut args = std::env::args_os();
+    // remove argv[0]
+    let _ = args.nth(0);
+    if args.len() != no_of_positional_args {
+        die_user_error(current_prog_name, format!("Expected {} arguments, got {}, namely {:?}", no_of_positional_args, args.len(), args.collect::<Vec<_>>()))
+    }
+    args.map(|arg| arg.into_vec()).collect()
+}
+
 pub fn args_for_exec(current_prog_name: &str, no_of_positional_args: usize) -> (Vec<Vec<u8>>, Vec<Vec<u8>>) {
     let mut args = std::env::args_os();
     // remove argv[0]
diff --git a/users/Profpatsch/netencode/default.nix b/users/Profpatsch/netencode/default.nix
index 92672470e902..4965bb74f20c 100644
--- a/users/Profpatsch/netencode/default.nix
+++ b/users/Profpatsch/netencode/default.nix
@@ -109,7 +109,7 @@ let
 
     fn main() {
         let mut buf = vec![];
-        let (args, prog) = exec_helpers::args_for_exec("record-get", 1);
+        let args = exec_helpers::args("record-get", 1);
         let field = match std::str::from_utf8(&args[0]) {
             Ok(f) => f,
             Err(_e) => exec_helpers::die_user_error("record-get", format!("The field name needs to be valid unicode"))