fix: weak-link Apple mknodat

Author: mattsu2020

src/backend/libc/fs/syscalls.rs

@@ -1208,13 +1208,30 @@ pub(crate) fn mknodat(
     mode: Mode,
     dev: Dev,
 ) -> io::Result<()> {
+    let mode = (mode.bits() | file_type.as_raw_mode()) as c::mode_t;
+    let dev = dev.try_into().map_err(|_e| io::Errno::PERM)?;
+
+    // Older Apple platforms lack `mknodat`.
+    #[cfg(apple)]
     unsafe {
-        ret(c::mknodat(
-            borrowed_fd(dirfd),
-            c_str(path),
-            (mode.bits() | file_type.as_raw_mode()) as c::mode_t,
-            dev.try_into().map_err(|_e| io::Errno::PERM)?,
-        ))
+        weak! {
+            fn mknodat(
+                c::c_int,
+                *const ffi::c_char,
+                c::mode_t,
+                c::dev_t
+            ) -> c::c_int
+        }
+        // If we have `mknodat`, use it.
+        if let Some(libc_mknodat) = mknodat.get() {
+            return ret(libc_mknodat(borrowed_fd(dirfd), c_str(path), mode, dev));
+        }
+        Err(io::Errno::NOSYS)
+    }
+
+    #[cfg(not(apple))]
+    unsafe {
+        ret(c::mknodat(borrowed_fd(dirfd), c_str(path), mode, dev))
     }
 }
 

src/fs/at.rs

@@ -460,9 +460,11 @@ pub fn fclonefileat<Fd: AsFd, DstFd: AsFd, P: path::Arg>(
 /// # References
 ///  - [POSIX]
 ///  - [Linux]
+///  - [Apple]
 ///
 /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/mknodat.html
 /// [Linux]: https://man7.org/linux/man-pages/man2/mknodat.2.html
+/// [Apple]: https://github.com/apple-oss-distributions/xnu/blob/main/bsd/man/man2/mknodat.2
 #[cfg(not(any(
     target_os = "espidf",
     target_os = "horizon",
@@ -487,8 +489,10 @@ pub fn mknodat<P: path::Arg, Fd: AsFd>(
 ///
 /// # References
 ///  - [POSIX]
+///  - [Apple]
 ///
 /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/mkfifoat.html
+/// [Apple]: https://github.com/apple-oss-distributions/xnu/blob/main/bsd/man/man2/mkfifoat.2
 #[cfg(not(any(
     target_os = "espidf",
     target_os = "horizon",