1use std::ffi::{OsStr, OsString};
2use std::path::{Path, PathBuf};
3use std::{io, iter::repeat_with};
4
5use crate::error::IoResultExt;
6
7fn tmpname(prefix: &OsStr, suffix: &OsStr, rand_len: usize) -> OsString {
8 let mut buf = OsString::with_capacity(prefix.len() + suffix.len() + rand_len);
9 buf.push(prefix);
10 let mut char_buf = [0u8; 4];
11 for c in repeat_with(fastrand::alphanumeric).take(rand_len) {
12 buf.push(c.encode_utf8(&mut char_buf));
13 }
14 buf.push(suffix);
15 buf
16}
17
18pub fn create_helper<R>(
19 base: &Path,
20 prefix: &OsStr,
21 suffix: &OsStr,
22 random_len: usize,
23 mut f: impl FnMut(PathBuf) -> io::Result<R>,
24) -> io::Result<R> {
25 let num_retries = if random_len != 0 {
26 crate::NUM_RETRIES
27 } else {
28 1
29 };
30
31 for _ in 0..num_retries {
32 let path = base.join(tmpname(prefix, suffix, random_len));
33 return match f(path) {
34 Err(ref e) if e.kind() == io::ErrorKind::AlreadyExists && num_retries > 1 => continue,
35 // AddrInUse can happen if we're creating a UNIX domain socket and
36 // the path already exists.
37 Err(ref e) if e.kind() == io::ErrorKind::AddrInUse && num_retries > 1 => continue,
38 res => res,
39 };
40 }
41
42 Err(io::Error::new(
43 io::ErrorKind::AlreadyExists,
44 "too many temporary files exist",
45 ))
46 .with_err_path(|| base)
47}
48