Constant SYS_OPENAT 

pub const SYS_OPENAT: usize = 462;

Open a file relative to a directory FD.

• dirfd: directory file descriptor (or AT_FDCWD)
• path_ptr: pointer to the path string
• path_len: length of the path
• flags: open flags

Returns a file descriptor. If path_ptr is absolute, dirfd is ignored.