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Impl new API std::os::unix::fs::mkfifo under feature unix_fifo #139450

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Impl new API std::os::unix::fs::mkfifo under feature unix_fifo #139450

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36 changes: 36 additions & 0 deletions library/std/src/os/unix/fs.rs
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Expand Up @@ -1100,3 +1100,39 @@ pub fn lchown<P: AsRef<Path>>(dir: P, uid: Option<u32>, gid: Option<u32>) -> io:
pub fn chroot<P: AsRef<Path>>(dir: P) -> io::Result<()> {
sys::fs::chroot(dir.as_ref())
}

/// Create a FIFO special file at the specified path with the specified mode.
///
/// # Examples
///
/// ```no_run
/// # #![feature(unix_mkfifo)]
/// # #[cfg(not(unix))]
/// # fn main() {}
/// # #[cfg(unix)]
/// # fn main() -> std::io::Result<()> {
/// # use std::{
/// # os::unix::fs::{mkfifo, PermissionsExt},
/// # fs::{File, Permissions, remove_file},
/// # io::{Write, Read},
/// # };
/// # let _ = remove_file("/tmp/fifo");
/// mkfifo("/tmp/fifo", Permissions::from_mode(0o774))?;
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If this test is to be run (I think it's a good idea to have some form of test), it may be better to call mkdtemp and create the FIFO there to ensure it doesn't interfere with anyone who actually has a /tmp/fifo.

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I'm not sure if we can use libc::mktemp here...honestly maybe we should also add a function for that

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Agreed, it would be nice to have. libc isn't available but the binding is pretty easy, the setup is a bit clunky but I think it's worth avoiding any possible issues

/// # // Use a temporary file to avoid conflicts or cleanup issues
/// # extern "C" { fn mktemp(template: *mut c_char) -> *mut c_char; }
/// # let mut buf = b"rust-fifo-XXXXXX\0";
/// # let fname = unsafe {
/// #     let ptr = mktemp(buf.as_ptr().cast::<c_char>()) };
/// #     assert!(!ptr.is_null(), "could not create tempfile");
/// #     CStr::from_ptr(ptr).to_str().unwrap()
/// # };
/// mkfifo(fname, Permissions::from_mode(0o774))?;
/// // ...

The rest LGTM

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My problem with this is portability, not sure if it would work on musl, and probably android and other libc reliably.

If we want to do this, might be easier to random generate the filename using std::random?

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Fair point. We have tempfile for the std testsuite, maybe just make the doc example no_run and then add the actual test there?

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Yeah that makes more sense, I would do that

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I see this was made no_run but it doesn't look like a test wasn't added. If you don't have it yet, just copy+paste this example to std/src/os/unix/fs/tests.rs using a file name from crate_helpers::tmpdir().join("fifo").

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Oops, I put it in std/tests/mkfifo.rs and forgot to git add it

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@tgross35 I have updated std/src/os/unix/fs/tests.rs

///
/// let mut wx = File::options().read(true).write(true).open("/tmp/fifo")?;
/// let mut rx = File::open("/tmp/fifo")?;
///
/// wx.write_all(b"hello, world!")?;
/// drop(wx);
///
/// let mut s = String::new();
/// rx.read_to_string(&mut s)?;
///
/// assert_eq!(s, "hello, world!");
/// # Ok(())
/// # }
/// ```
#[unstable(feature = "unix_mkfifo", issue = "139324")]
pub fn mkfifo<P: AsRef<Path>>(path: P, permissions: Permissions) -> io::Result<()> {
sys::fs::mkfifo(path.as_ref(), permissions.mode())
}
20 changes: 20 additions & 0 deletions library/std/src/os/unix/fs/tests.rs
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Expand Up @@ -55,3 +55,23 @@ fn write_vectored_at() {
let content = fs::read(&filename).unwrap();
assert_eq!(&content, expected);
}

#[test]
fn test_mkfifo() {
let tmp_dir = crate::test_helpers::tmpdir();

let fifo = tmp_dir.path().join("fifo");

mkfifo(&fifo, Permissions::from_mode(0o774)).unwrap();

let mut wx = fs::File::options().read(true).write(true).open(&fifo).unwrap();
let mut rx = fs::File::open(fifo).unwrap();

wx.write_all(b"hello, world!").unwrap();
drop(wx);

let mut s = String::new();
rx.read_to_string(&mut s).unwrap();

assert_eq!(s, "hello, world!");
}
2 changes: 1 addition & 1 deletion library/std/src/sys/fs/mod.rs
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Expand Up @@ -9,7 +9,7 @@ cfg_if::cfg_if! {
if #[cfg(target_family = "unix")] {
mod unix;
use unix as imp;
pub use unix::{chown, fchown, lchown};
pub use unix::{chown, fchown, lchown, mkfifo};
#[cfg(not(target_os = "fuchsia"))]
pub use unix::chroot;
pub(crate) use unix::debug_assert_fd_is_open;
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6 changes: 6 additions & 0 deletions library/std/src/sys/fs/unix.rs
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Expand Up @@ -2148,6 +2148,12 @@ pub fn chroot(dir: &Path) -> io::Result<()> {
Err(io::const_error!(io::ErrorKind::Unsupported, "chroot not supported by vxworks"))
}

pub fn mkfifo(path: &Path, mode: u32) -> io::Result<()> {
run_path_with_cstr(path, &|path| {
cvt(unsafe { libc::mkfifo(path.as_ptr(), mode.try_into().unwrap()) }).map(|_| ())
})
}

pub use remove_dir_impl::remove_dir_all;

// Fallback for REDOX, ESP-ID, Horizon, Vita, Vxworks and Miri
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