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use std::ffi::{OsStr, OsString};
use std::path::{Path, PathBuf};
use std::{io, iter::repeat_with};
use crate::error::IoResultExt;
fn tmpname(prefix: &OsStr, suffix: &OsStr, rand_len: usize) -> OsString {
let capacity = prefix
.len()
.saturating_add(suffix.len())
.saturating_add(rand_len);
let mut buf = OsString::with_capacity(capacity);
buf.push(prefix);
let mut char_buf = [0u8; 4];
for c in repeat_with(fastrand::alphanumeric).take(rand_len) {
buf.push(c.encode_utf8(&mut char_buf));
}
buf.push(suffix);
buf
}
pub fn create_helper<R>(
base: &Path,
prefix: &OsStr,
suffix: &OsStr,
random_len: usize,
permissions: Option<&std::fs::Permissions>,
mut f: impl FnMut(PathBuf, Option<&std::fs::Permissions>) -> io::Result<R>,
) -> io::Result<R> {
let num_retries = if random_len != 0 {
crate::NUM_RETRIES
} else {
1
};
for _ in 0..num_retries {
let path = base.join(tmpname(prefix, suffix, random_len));
return match f(path, permissions) {
Err(ref e) if e.kind() == io::ErrorKind::AlreadyExists && num_retries > 1 => continue,
// AddrInUse can happen if we're creating a UNIX domain socket and
// the path already exists.
Err(ref e) if e.kind() == io::ErrorKind::AddrInUse && num_retries > 1 => continue,
res => res,
};
}
Err(io::Error::new(
io::ErrorKind::AlreadyExists,
"too many temporary files exist",
))
.with_err_path(|| base)
}