mod-tempdir 0.9.0

Temporary directory management for Rust. Auto-cleanup on Drop, collision-resistant naming, cross-platform paths. Zero runtime deps by default; opt-in mod-rand feature for uniformly distributed naming. tempfile replacement at MSRV 1.75.
Documentation

What it does

Creates a temporary directory, hands you the path, and deletes it (recursively) when the handle goes out of scope. The OS-standard temp location is used on every supported platform: %TEMP% on Windows, /tmp on Linux and macOS, anywhere std::env::temp_dir() points elsewhere.

Cleanup is best-effort. A failure during drop (file still held open, permission denied, network filesystem hiccup) is silent: a Drop impl must not panic. Use persist() if you want the directory to survive past drop so you can inspect it.

Why a tempfile replacement

The tempfile crate pulls in getrandom 0.4, which uses edition2024 and requires Rust 1.85+. If your project supports an older MSRV, that single dependency forces the rest of your build to follow.

mod-tempdir provides the same core capability at MSRV 1.75. The default build has zero runtime dependencies outside std. An opt-in feature delegates name generation to mod-rand::tier2 when you want uniformly distributed names from a separately maintained generator; the public API is identical either way.

The current trade: no NamedTempFile companion type (just directories) and no cleanup-on-startup pass for orphaned dirs from crashed processes. Both are tracked for later releases in the 0.9.x line.

Quick start

[dependencies]
mod-tempdir = "0.9"

use mod_tempdir::TempDir;

let dir = TempDir::new()?;
let file_path = dir.path().join("test.txt");
std::fs::write(&file_path, b"hello")?;
// `dir` and its contents are deleted at end of scope.
# Ok::<(), std::io::Error>(())

API

TempDir::new()                  // -> io::Result<TempDir>
TempDir::with_prefix("test")    // -> io::Result<TempDir> with custom prefix
dir.path()                       // -> &Path
dir.persist()                    // -> PathBuf (disables cleanup)
dir.cleanup_on_drop()            // -> bool

The signature surface has not changed since 0.1.0 and will not change again before 1.0.0. Additions land as new methods only.

Feature flags

Flag Default Effect
mod-rand off Use mod_rand::tier2::unique_name for directory naming. Adds one optional dependency (mod-rand, itself free of further deps).

Default naming uses an internal mixer over the process ID, the nanosecond clock, and a per-process atomic counter. It is fast, collision-free within a process, and good enough for test fixtures.

The mod-rand feature swaps that mixer for mod_rand::tier2, a SplitMix + Stafford-finisher pipeline that produces a uniform distribution across the alphabet without changing how names look on disk. Enable when you want the stronger statistical properties of a tested generator. Both paths use the same Crockford base32 alphabet (0-9A-Z minus I, L, O, U), so a caller that inspects directory basenames keeps working when the feature is toggled.

[dependencies]
mod-tempdir = { version = "0.9", features = ["mod-rand"] }

How it picks unique names

By default, the name is derived from:

  • Process ID (PID)
  • Current nanosecond timestamp
  • An atomic counter that guarantees uniqueness within a process

This is collision-resistant enough for test fixtures and concurrent local work. It is not cryptographically secure. If you need crypto-quality random names (for example, for security-sensitive temp paths), generate one with mod_rand::tier3 and pass it to TempDir::with_prefix.

Concurrency

TempDir::new() and TempDir::with_prefix() are safe to call from many threads at once. The verification suite includes a stress test that fires 256 threads through a shared barrier and asserts every returned path is distinct. The same test runs on both feature configurations.

The dev-* and mod-* ecosystem

This crate is the foundation for dev-fixtures's temporary working directories. It also slots cleanly into any project that needs auto-cleanup temp dirs without pulling in tempfile's dep tree.

Roadmap

v0.9.0 ships the mod-rand integration. The public API is the one introduced in v0.1.0. Remaining items before v1.0.0:

  • v0.9.1: optional fsys integration for cross-platform filesystem primitives
  • v0.9.2: NamedTempFile companion type
  • v0.9.3: cleanup-on-startup pass for orphaned dirs from crashed processes
  • v1.0.0: API stabilization

Minimum supported Rust version

1.75. Pinned in Cargo.toml and verified by CI on every push.

License

Apache-2.0. See LICENSE.