Hey, thanks for building this awesome crate! I have been using NamedTempFile from the tempfile crate for this purpose before but this seems more convenient and robust from the how-it-works description in the docs.

There's a small problem with the readme, the docs badge link is broken.

Apparently overlayfs, used by container software, doesn't support unnamed tempfiles: launchbadge/sqlx#2908

It would be nice to be able to easily use O_TMPFILE when it is supported, and fall back to a different behavior when it isn't. Currently, there's just the Cargo feature (and a library can't be sure that it's disabled, since some other package in an application's dependency tree might activate the it).

After reading more I found it's recommended to fsync parent also to be sure data is persisted ok.
You can see here more https://www.quora.com/Linux/When-should-you-fsync-the-containing-directory-in-addition-to-the-file-itself
Also I see other implementations are doing it https://github.com/untitaker/rust-atomicwrites/blob/master/src/lib.rs#L200

It's not a bit deal, I can fsync parent after commit but would be nice to have this included

It returns an error when commit, opening with tempfile::NamedTempFile.path().
Access is denied. (os error 5)

dependencies

├── anyhow v1.0.81
├── atomic-write-file v0.1.3
│   └── rand v0.8.5
│       ├── rand_chacha v0.3.1
│       │   ├── ppv-lite86 v0.2.17
│       │   └── rand_core v0.6.4
│       │       └── getrandom v0.2.14
│       │           └── cfg-if v1.0.0
│       └── rand_core v0.6.4 (*)
└── tempfile v3.10.1
    ├── cfg-if v1.0.0
    ├── fastrand v2.0.2
    └── windows-sys v0.52.0
        └── windows-targets v0.52.4
            └── windows_x86_64_msvc v0.52.4

Platform

Windows

Code

use anyhow::Result;
use atomic_write_file::AtomicWriteFile;
use tempfile::NamedTempFile;

fn main() -> Result<()> {
    let file = NamedTempFile::new()?;
    let path = file.path();
    let atomic = AtomicWriteFile::open(path)?;
    atomic.commit()?;
    Ok(())
}

Output

Error: 拒绝访问。 (os error 5)

1. make a file manually echo foo > filename
2. make it immutable chattr +i filename
3. try to write over it with this library

    	let mut file = AtomicWriteFile::options().open("filename")?;
	writeln!(file, "{}", contents)?;
	file.commit()?;

4. exit without error
5. tmp file still exists and file did not get overwritten

A call to fsync() on a O_TMPFILE does nothing. Now, the anonymous file is given a temporary name then renamed to its final name, without an fsync() call in between. A power failure following the final rename may result in data loss -- the target file now contains no data, filesize is zero.

Take a look at the btrfs source code in the kernel, where the no-op behavior of fsync() is described: https://github.com/torvalds/linux/blob/026e680b0a08a62b1d948e5a8ca78700bfac0e6e/fs/btrfs/tree-log.c#L2422