diff --git a/src/uu/false/src/false.rs b/src/uu/false/src/false.rs index 324f90579..b304b4af6 100644 --- a/src/uu/false/src/false.rs +++ b/src/uu/false/src/false.rs @@ -4,16 +4,43 @@ // * // * For the full copyright and license information, please view the LICENSE // * file that was distributed with this source code. +use clap::{App, AppSettings, ErrorKind}; +use std::io::Write; +use uucore::error::{set_exit_code, UResult}; -use clap::App; -use uucore::error::UResult; +static ABOUT: &str = " + Returns false, an unsuccessful exit status. + + Immediately returns with the exit status `1`. When invoked with one of the recognized options it + will try to write the help or version text. Any IO error during this operation is diagnosed, yet + the program will also return `1`. +"; #[uucore::main] pub fn uumain(args: impl uucore::Args) -> UResult<()> { - uu_app().get_matches_from(args); - Err(1.into()) + let app = uu_app(); + + // Mirror GNU options, always return `1`. In particular even the 'successful' cases of no-op, + // and the interrupted display of help and version should return `1`. Also, we return Ok in all + // paths to avoid the allocation of an error object, an operation that could, in theory, fail + // and unwind through the standard library allocation handling machinery. + set_exit_code(1); + + if let Err(err) = app.try_get_matches_from(args) { + if let ErrorKind::DisplayHelp | ErrorKind::DisplayVersion = err.kind { + if let Err(print_fail) = err.print() { + // Try to display this error. + let _ = writeln!(std::io::stderr(), "{}: {}", uucore::util_name(), print_fail); + } + } + } + + Ok(()) } pub fn uu_app<'a>() -> App<'a> { App::new(uucore::util_name()) + .version(clap::crate_version!()) + .about(ABOUT) + .setting(AppSettings::InferLongArgs) }