tvl-depot/users/Profpatsch/execline/exec_helpers.rs
Profpatsch 83634341aa feat(users/Profpatsch/execline): add args_for_exec
`exec_into_args` would just read argv and exec into it, but we want to
be able to write commands which take some positional arguments first.

Thus we split the invocation into `args_for_exec`, which returns the
positional arguments and prog, and then pass prog to `exec_into_args`
when we want to exec eventually (prog is still an iterator at this
point).

Change-Id: I0b180c1a100b96363fe33ba2c42034ed41716b7a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2474
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>
2021-01-31 16:06:25 +00:00

41 lines
1.7 KiB
Rust

use std::os::unix::process::CommandExt;
use std::ffi::OsStr;
use std::os::unix::ffi::{OsStringExt, OsStrExt};
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]
let _ = args.nth(0);
let mut args = args.map(|arg| arg.into_vec());
let mut pos_args = vec![];
// get positional args
for i in 1..no_of_positional_args {
pos_args.push(
args.nth(0).expect(
&format!("{}: expects {} positional args, only got {}", current_prog_name, no_of_positional_args, i))
);
}
// prog... is the rest of the iterator
let prog : Vec<Vec<u8>> = args.collect();
(pos_args, prog)
}
pub fn exec_into_args<'a, 'b, Args, Arg, Env, Key, Val>(current_prog_name: &str, args: Args, env_additions: Env) -> !
where
Args: IntoIterator<Item = Arg>,
Arg: AsRef<[u8]>,
Env: IntoIterator<Item = (Key, Val)>,
Key: AsRef<[u8]>,
Val: AsRef<[u8]>,
{
// TODO: is this possible without collecting into a Vec first, just leaving it an IntoIterator?
let args = args.into_iter().collect::<Vec<Arg>>();
let mut args = args.iter().map(|v| OsStr::from_bytes(v.as_ref()));
let prog = args.nth(1).expect(&format!("{}: first argument must be an executable", current_prog_name));
// TODO: same here
let env = env_additions.into_iter().collect::<Vec<(Key, Val)>>();
let env = env.iter().map(|(k,v)| (OsStr::from_bytes(k.as_ref()), OsStr::from_bytes(v.as_ref())));
let err = std::process::Command::new(prog).args(args).envs(env).exec();
panic!("{}: exec failed: {:?}", current_prog_name, err);
}