1use std::env;
2use std::path::{Path, PathBuf};
3
4// Once rust 1.70 is wide-spread (Debian stable), we can use OnceLock from stdlib.
5use once_cell::sync::OnceCell as OnceLock;
6
7static DEFAULT_TEMPDIR: OnceLock<PathBuf> = OnceLock::new();
8
9/// Override the default temporary directory (defaults to [`std::env::temp_dir`]). This function
10/// changes the _global_ default temporary directory for the entire program and should not be called
11/// except in exceptional cases where it's not configured correctly by the platform.
12///
13/// Only the first call to this function will succeed. All further calls will fail with `Err(path)`
14/// where `path` is previously set default temporary directory override.
15///
16/// **NOTE:** This function does not check if the specified directory exists and/or is writable.
17pub fn override_temp_dir(path: &Path) -> Result<(), PathBuf> {
18 let mut we_set: bool = false;
19 let val: &PathBuf = DEFAULT_TEMPDIR.get_or_init(|| {
20 we_set = true;
21 path.to_path_buf()
22 });
23 if we_set {
24 Ok(())
25 } else {
26 Err(val.to_owned())
27 }
28}
29
30/// Returns the default temporary directory, used for both temporary directories and files if no
31/// directory is explicitly specified.
32///
33/// This function simply delegates to [`std::env::temp_dir`] unless the default temporary directory
34/// has been override by a call to [`override_temp_dir`].
35///
36/// **NOTE:** This function does check if the returned directory exists and/or is writable.
37pub fn temp_dir() -> PathBuf {
38 DEFAULT_TEMPDIROption
39 .get()
40 .map(|p: &PathBuf| p.to_owned())
41 // Don't cache this in case the user uses std::env::set to change the temporary directory.
42 .unwrap_or_else(env::temp_dir)
43}
44