sudoers: null byte terminated username not treated as a syntax error

[japaric]

relevant test

sudo-rs/test-framework/sudo-compliance-tests/src/sudo/sudoers/user_list.rs

Lines 412 to 427 in cfc735f

	#[test]
	fn null_byte_terminated_username() -> Result<()> {
	let env = Env("ferris\0 ALL=(ALL:ALL) NOPASSWD: ALL")
	.user("ferris")
	.build()?;
	let output = Command::new("sudo")
	.arg("true")
	.as_user("ferris")
	.output(&env)?;
	assert!(!output.status().success());
	assert_contains!(output.stderr(), "syntax error");
	Ok(())
	}

ogsudo rejects the sudoers file and does not allow the user to run sudo. sudo-rs lets the user run sudo

[squell]

There is an interplay between two issues here:

• a commit that addressed this (and also changes the sentinel value to a more type-safe solution) was never pushed for some reason
• the illegal escape sequence error is suppressed, seems like that happens in the whitespace parser

This is a nice bug, harmless but interesting.