extern crate memfd;
use memfd::errors::Result;

fn new_sized_memfd() -> Result<memfd::Memfd> {
    // Create a sealable memfd.
    let opts = memfd::MemfdOptions::default().allow_sealing(true);
    let mfd = opts.create("sized-1K")?;

    // Resize to 1024B.
    mfd.as_file().set_len(1024)?;

    // Add seals to prevent further resizing.
    let mut seals = memfd::SealsHashSet::new();
    seals.insert(memfd::FileSeal::SealShrink);
    seals.insert(memfd::FileSeal::SealGrow);
    mfd.add_seals(&seals)?;

    // Prevent further sealing changes.
    mfd.add_seal(memfd::FileSeal::SealSeal);

    Ok(mfd)
}