vendor/tempfile/src/util.rs

   1 use rand::distributions::Alphanumeric;
   2 use rand::{self, Rng};
   3 use std::ffi::{OsStr, OsString};
   4 use std::path::{Path, PathBuf};
   5 use std::{io, str};
   6
   7 use crate::error::IoResultExt;
   8
   9 fn tmpname(prefix: &OsStr, suffix: &OsStr, rand_len: usize) -> OsString {
  10     let mut buf = OsString::with_capacity(prefix.len() + suffix.len() + rand_len);
  11     buf.push(prefix);
  12
  13     // Push each character in one-by-one. Unfortunately, this is the only
  14     // safe(ish) simple way to do this without allocating a temporary
  15     // String/Vec.
  16     unsafe {
  17         rand::thread_rng()
  18             .sample_iter(&Alphanumeric)
  19             .take(rand_len)
  20             .for_each(|b| buf.push(str::from_utf8_unchecked(&[b as u8])))
  21     }
  22     buf.push(suffix);
  23     buf
  24 }
  25
  26 pub fn create_helper<F, R>(
  27     base: &Path,
  28     prefix: &OsStr,
  29     suffix: &OsStr,
  30     random_len: usize,
  31     f: F,
  32 ) -> io::Result<R>
  33 where
  34     F: Fn(PathBuf) -> io::Result<R>,
  35 {
  36     let num_retries = if random_len != 0 {
  37         crate::NUM_RETRIES
  38     } else {
  39         1
  40     };
  41
  42     for _ in 0..num_retries {
  43         let path = base.join(tmpname(prefix, suffix, random_len));
  44         return match f(path) {
  45             Err(ref e) if e.kind() == io::ErrorKind::AlreadyExists => continue,
  46             res => res,
  47         };
  48     }
  49
  50     Err(io::Error::new(
  51         io::ErrorKind::AlreadyExists,
  52         "too many temporary files exist",
  53     ))
  54     .with_err_path(|| base)
  55 }