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

Tracking issue rust-lang#139324

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

Author: NobodyXu

library/std/src/os/unix/fs.rs

@@ -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))?;
+///
+/// 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())
+}

library/std/src/os/unix/fs/tests.rs

@@ -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!");
+}

library/std/src/sys/fs/mod.rs

@@ -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;

library/std/src/sys/fs/unix.rs

@@ -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