Replace fastrand with getrandom and base64

Cargo.toml

@@ -17,8 +17,9 @@ repository = "https://github.com/Stebalien/tempfile"
 description = "A library for managing temporary files and directories."
 
 [dependencies]
+base64 = "0.13.0"
 cfg-if = "1"
-fastrand = "1.6.0"
+getrandom = "0.2.7"
 remove_dir_all = "0.5"
 
 [target.'cfg(any(unix, target_os = "wasi"))'.dependencies]

src/util.rs

@@ -1,16 +1,43 @@
 use std::ffi::{OsStr, OsString};
 use std::path::{Path, PathBuf};
-use std::{io, iter::repeat_with};
+use std::io;
 
 use crate::error::IoResultExt;
 
+fn calculate_rand_buf_len(alphanumeric_len: usize) -> usize {
+ let expected_non_alphanumeric_chars = alphanumeric_len / 32;
+ (alphanumeric_len + expected_non_alphanumeric_chars) * 3 / 4 + 3
+}
+
+fn calculate_base64_len(binary_len: usize) -> usize {
+ binary_len * 4 / 3 + 4
+}
+
+fn fill_with_random_base64(rand_buf: &mut [u8], char_buf: &mut Vec<u8>) {
+ getrandom::getrandom(rand_buf).expect("calling getrandom failed");
+ char_buf.resize(calculate_base64_len(rand_buf.len()), 0);
+ base64::encode_config_slice(rand_buf, base64::STANDARD_NO_PAD, char_buf);
+}
+
 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);
- let mut char_buf = [0u8; 4];
- for c in repeat_with(fastrand::alphanumeric).take(rand_len) {
- buf.push(c.encode_utf8(&mut char_buf));
+
+ let mut rand_buf = vec![0; calculate_rand_buf_len(rand_len)];
+ let mut char_buf = vec![0; calculate_base64_len(rand_buf.len())];
+ let mut remaining_chars = rand_len;
+ loop {
+ fill_with_random_base64(&mut rand_buf, &mut char_buf);
+ char_buf.retain(|&c| (c != b'+') & (c != b'/') & (c != 0));
+ if char_buf.len() >= remaining_chars {
+ buf.push(std::str::from_utf8(&char_buf[..remaining_chars]).unwrap());
+ break;
+ } else {
+ buf.push(std::str::from_utf8(&char_buf).unwrap());
+ remaining_chars -= char_buf.len();
+ }
  }
+
  buf.push(suffix);
  buf
 }

tests/namedtempfile.rs

@@ -387,55 +387,3 @@ fn test_make_uds() {
 
  assert!(temp_sock.path().exists());
 }
-
-#[cfg(unix)]
-#[test]
-fn test_make_uds_conflict() {
- use std::os::unix::net::UnixListener;
- use std::sync::atomic::{AtomicUsize, Ordering};
- use std::sync::Arc;
-
- // Check that retries happen correctly by racing N different threads.
-
- const NTHREADS: usize = 20;
-
- // The number of times our callback was called.
- let tries = Arc::new(AtomicUsize::new(0));
-
- let mut threads = Vec::with_capacity(NTHREADS);
-
- for _ in 0..NTHREADS {
- let tries = tries.clone();
- threads.push(std::thread::spawn(move || {
- // Ensure that every thread uses the same seed so we are guaranteed
- // to retry. Note that fastrand seeds are thread-local.
- fastrand::seed(42);
-
- Builder::new()
- .prefix("tmp")
- .suffix(".sock")
- .rand_bytes(12)
- .make(|path| {
- tries.fetch_add(1, Ordering::Relaxed);
- UnixListener::bind(path)
- })
- }));
- }
-
- // Join all threads, but don't drop the temp file yet. Otherwise, we won't
- // get a deterministic number of `tries`.
- let sockets: Vec<_> = threads
- .into_iter()
- .map(|thread| thread.join().unwrap().unwrap())
- .collect();
-
- // Number of tries is exactly equal to (n*(n+1))/2.
- assert_eq!(
- tries.load(Ordering::Relaxed),
- (NTHREADS * (NTHREADS + 1)) / 2
- );
-
- for socket in sockets {
- assert!(socket.path().exists());
- }
-}