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use rand::distributions::Alphanumeric;
use rand::{self, Rng};
use std::ffi::{OsStr, OsString};
use std::path::{Path, PathBuf};
use std::{io, str};
use crate::error::IoResultExt;
fn tmpname(prefix: &OsStr, suffix: &OsStr, rand_len: usize) -> OsString {
let mut buf = OsString::with_capacity(prefix.len() + suffix.len() + rand_len);
buf.push(prefix);
// Push each character in one-by-one. Unfortunately, this is the only
// safe(ish) simple way to do this without allocating a temporary
// String/Vec.
unsafe {
rand::thread_rng()
.sample_iter(&Alphanumeric)
.take(rand_len)
.for_each(|b| buf.push(str::from_utf8_unchecked(&[b as u8])))
}
buf.push(suffix);
buf
}
pub fn create_helper<F, R>(
base: &Path,
prefix: &OsStr,
suffix: &OsStr,
random_len: usize,
f: F,
) -> io::Result<R>
where
F: Fn(PathBuf) -> 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) {
Err(ref e) if e.kind() == io::ErrorKind::AlreadyExists => continue,
res => res,
};
}
Err(io::Error::new(
io::ErrorKind::AlreadyExists,
"too many temporary files exist",
))
.with_err_path(|| base)
}
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