Function make_memfd

vmm/src/memory_manager.rs:3318–3328

(size: u64)

    use super::{next_data_extent, write_region_sparse};

    fn make_memfd(size: u64) -> std::fs::File {
        // SAFETY: memfd_create is a self-contained syscall; we own the
        // returned fd.
        let fd = unsafe { libc::syscall(libc::SYS_memfd_create, c"sparse-test".as_ptr(), 0u32) };
        assert!(fd >= 0, "memfd_create failed");
        // SAFETY: memfd_create returned a valid fd that we now own; wrap it
        // in File so it is closed on drop.
        let f = unsafe { std::fs::File::from_raw_fd(fd as i32) };
        f.set_len(size).unwrap();
        f
    }

    fn collect_extents(
        fd: BorrowedFd<'_>,