1 files changed, 80 insertions, 0 deletions
diff --git a/vendor/rustix/src/fs/special.rs b/vendor/rustix/src/fs/special.rs
new file mode 100644
index 00000000..276a775f
--- /dev/null
+++ b/vendor/rustix/src/fs/special.rs
@@ -0,0 +1,80 @@
+//! The `CWD` and `ABS` constants, representing the current working directory
+//! and absolute-only paths, respectively.
+//!
+//! # Safety
+//!
+//! This file uses `AT_FDCWD`, which is a raw file descriptor, but which is
+//! always valid, and `-EBADF`, which is an undocumented by commonly used
+//! convention of passing a value which will always fail if the accompanying
+//! path isn't absolute.
+
+#![allow(unsafe_code)]
+
+use crate::backend;
+use backend::c;
+use backend::fd::{BorrowedFd, RawFd};
+
+/// `AT_FDCWD`—A handle representing the current working directory.
+///
+/// This is a file descriptor which refers to the process current directory
+/// which can be used as the directory argument in `*at` functions such as
+/// [`openat`].
+///
+/// # References
+///  - [POSIX]
+///
+/// [`openat`]: crate::fs::openat
+/// [POSIX]: https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/fcntl.h.html
+// SAFETY: `AT_FDCWD` is a reserved value that is never dynamically
+// allocated, so it'll remain valid for the duration of `'static`.
+#[cfg(not(target_os = "horizon"))]
+#[doc(alias = "AT_FDCWD")]
+pub const CWD: BorrowedFd<'static> =
+    unsafe { BorrowedFd::<'static>::borrow_raw(c::AT_FDCWD as RawFd) };
+
+/// `-EBADF`—A handle that requires paths to be absolute.
+///
+/// This is a file descriptor which refers to no directory, which can be used
+/// as the directory argument in `*at` functions such as [`openat`], which
+/// causes them to fail with [`BADF`] if the accompanying path is not absolute.
+///
+/// This corresponds to the undocumented by commonly used convention of
+/// passing `-EBADF` as the `dirfd` argument, which is ignored if the path is
+/// absolute, and evokes an `EBADF` error otherwise.
+///
+/// [`openat`]: crate::fs::openat
+/// [`BADF`]: crate::io::Errno::BADF
+// SAFETY: This `-EBADF` convention is commonly used, such as in lxc, so OS's
+// aren't going to break it.
+pub const ABS: BorrowedFd<'static> =
+    unsafe { BorrowedFd::<'static>::borrow_raw(c::EBADF.wrapping_neg() as RawFd) };
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::fd::AsRawFd as _;
+
+    #[test]
+    fn test_cwd() {
+        assert!(CWD.as_raw_fd() != -1);
+        assert!(CWD.as_raw_fd() != c::STDIN_FILENO);
+        assert!(CWD.as_raw_fd() != c::STDOUT_FILENO);
+        assert!(CWD.as_raw_fd() != c::STDERR_FILENO);
+        #[cfg(linux_kernel)]
+        #[cfg(feature = "io_uring")]
+        assert!(CWD.as_raw_fd() != crate::io_uring::IORING_REGISTER_FILES_SKIP.as_raw_fd());
+    }
+
+    #[test]
+    fn test_abs() {
+        assert!(ABS.as_raw_fd() < 0);
+        assert!(ABS.as_raw_fd() != -1);
+        assert!(ABS.as_raw_fd() != c::AT_FDCWD);
+        assert!(ABS.as_raw_fd() != c::STDIN_FILENO);
+        assert!(ABS.as_raw_fd() != c::STDOUT_FILENO);
+        assert!(ABS.as_raw_fd() != c::STDERR_FILENO);
+        #[cfg(linux_kernel)]
+        #[cfg(feature = "io_uring")]
+        assert!(ABS.as_raw_fd() != crate::io_uring::IORING_REGISTER_FILES_SKIP.as_raw_fd());
+    }
+}