Function dup3

#[no_mangle]
pub unsafe extern "C" fn dup3(
    old_fd: c_int,
    new_fd: c_int,
    flags: c_int,
) -> c_int

Available on crate feature fd only.

Duplicate a file descriptor, the caller can force the close-on-exec flag to be set for the new file descriptor by specifying O_CLOEXEC in flags.

If oldfd equals newfd, then dup3() fails with the error EINVAL.