1 use std::env;
2 use std::path::{Path, PathBuf};
3 
4 // Once rust 1.70 is wide-spread (Debian stable), we can use OnceLock from stdlib.
5 use once_cell::sync::OnceCell as OnceLock;
6 
7 static 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.
override_temp_dir(path: &Path) -> Result<(), PathBuf>17 pub fn override_temp_dir(path: &Path) -> Result<(), PathBuf> {
18     let mut we_set = false;
19     let val = 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.
temp_dir() -> PathBuf37 pub fn temp_dir() -> PathBuf {
38     DEFAULT_TEMPDIR
39         .get()
40         .map(|p| 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