//! Busy mount teardown and generation-change guest probe.

use super::*;
use os_vfs_unmount::{Error, Kind, Mount};

pub fn run(allocator: &mut memory::FrameAllocator) -> Result<(), &'static str> {
    let frames_before = allocator.remaining_pages();
    let mut mount = Mount::new(2, 7).map_err(|_| "k1600-new")?;
    let old = mount.token();
    let open = mount.acquire(Kind::Open).map_err(|_| "k1600-open")?;
    let lookup = mount.acquire(Kind::Lookup).map_err(|_| "k1600-lookup")?;
    let pin = mount.acquire(Kind::CachePin).map_err(|_| "k1600-pin")?;
    let before_all = mount;
    if mount.unmount() != Err(Error::Busy) || mount != before_all {
        return Err("k1600-all-busy");
    }
    write_line("TURKOS/OS/K1600-MOUNT: OPEN-LOOKUP=BUSY");

    mount.release(open).map_err(|_| "k1600-release-open")?;
    mount.release(lookup).map_err(|_| "k1600-release-lookup")?;
    let before_pin = mount;
    if mount.unmount() != Err(Error::Busy) || mount != before_pin {
        return Err("k1600-pin-busy");
    }
    write_line("TURKOS/OS/K1600-MOUNT: CACHE-PIN=BUSY");

    mount.release(pin).map_err(|_| "k1600-release-pin")?;
    if mount.unmount() != Ok(8) || mount.mounted() {
        return Err("k1600-unmount");
    }
    write_line("TURKOS/OS/K1600-MOUNT: UNMOUNT=GEN8");

    if mount.validate(old) != Err(Error::Stale)
        || mount.release(pin) != Err(Error::Stale)
        || mount.remount().map(|token| token.generation()) != Ok(8)
        || mount.validate(old) != Err(Error::Stale)
        || mount.validate(mount.token()) != Ok(()) {
        return Err("k1600-stale");
    }
    write_line("TURKOS/OS/K1600-MOUNT: STALE=REJECTED");

    let mut terminal = Mount::new(3, u64::MAX)
        .map_err(|_| "k1600-terminal")?;
    let before_overflow = terminal;
    if terminal.unmount() != Err(Error::Overflow)
        || terminal != before_overflow
        || allocator.remaining_pages() != frames_before {
        return Err("k1600-overflow");
    }
    write_line("TURKOS/OS/K1600-MOUNT: OVERFLOW=UNCHANGED FRAMES=UNCHANGED");
    Ok(())
}