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//! This crate contains a single public function
//! [`get_path_for_executable`](fn.get_path_for_executable.html).
//! See docs there for more information.
use std::{env, iter, path::PathBuf};
pub fn cargo() -> PathBuf {
get_path_for_executable("cargo")
}
pub fn rustc() -> PathBuf {
get_path_for_executable("rustc")
}
pub fn rustup() -> PathBuf {
get_path_for_executable("rustup")
}
/// Return a `PathBuf` to use for the given executable.
///
/// E.g., `get_path_for_executable("cargo")` may return just `cargo` if that
/// gives a valid Cargo executable; or it may return a full path to a valid
/// Cargo.
fn get_path_for_executable(executable_name: &'static str) -> PathBuf {
// The current implementation checks three places for an executable to use:
// 1) Appropriate environment variable (erroring if this is set but not a usable executable)
// example: for cargo, this checks $CARGO environment variable; for rustc, $RUSTC; etc
// 2) `<executable_name>`
// example: for cargo, this tries just `cargo`, which will succeed if `cargo` is on the $PATH
// 3) `~/.cargo/bin/<executable_name>`
// example: for cargo, this tries ~/.cargo/bin/cargo
// It seems that this is a reasonable place to try for cargo, rustc, and rustup
let env_var = executable_name.to_ascii_uppercase();
if let Some(path) = env::var_os(&env_var) {
return path.into();
}
if lookup_in_path(executable_name) {
return executable_name.into();
}
if let Some(mut path) = home::home_dir() {
path.push(".cargo");
path.push("bin");
path.push(executable_name);
if path.is_file() {
return path;
}
}
executable_name.into()
}
fn lookup_in_path(exec: &str) -> bool {
let paths = env::var_os("PATH").unwrap_or_default();
let mut candidates = env::split_paths(&paths).flat_map(|path| {
let candidate = path.join(&exec);
let with_exe = match env::consts::EXE_EXTENSION {
"" => None,
it => Some(candidate.with_extension(it)),
};
iter::once(candidate).chain(with_exe)
});
candidates.any(|it| it.is_file())
}
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