//! Reserved metadata bitmap and last-free-block guest probe.

use super::*;
use os_turkfs_allocation::{Bitmap, Counts, Error};

const METADATA: u64 = 0x1f;

pub fn run(allocator: &mut memory::FrameAllocator) -> Result<(), &'static str> {
    let frames_before = allocator.remaining_pages();
    let mut bitmap = Bitmap::validate(64, METADATA, u64::MAX & !(1u64 << 63))
        .map_err(|_| "k1625-valid")?;
    if bitmap.counts() != (Counts {reserved: 5, user: 58, free: 1})
        || bitmap.allocate() != Ok(63)
        || bitmap.counts() != (Counts {reserved: 5, user: 59, free: 0}) {
        return Err("k1625-last");
    }
    write_line("TURKOS/OS/K1625-BITMAP: LAST=63 OWNERS=64");

    let malformed = u64::MAX & !(1u64 << 2);
    if Bitmap::validate(64, METADATA, malformed) != Err(Error::ReservedFree) {
        return Err("k1625-reserved-free");
    }
    write_line("TURKOS/OS/K1625-BITMAP: RESERVED-FREE=REJECTED");

    let full = bitmap;
    if bitmap.allocate() != Err(Error::NoSpace) || bitmap != full {
        return Err("k1625-no-space");
    }
    write_line("TURKOS/OS/K1625-BITMAP: NOSPACE=UNCHANGED");

    if bitmap.release(2) != Err(Error::ReservedBlock) || bitmap != full
        || bitmap.release(63) != Ok(())
        || bitmap.counts() != (Counts {reserved: 5, user: 58, free: 1})
        || allocator.remaining_pages() != frames_before {
        return Err("k1625-release");
    }
    write_line("TURKOS/OS/K1625-BITMAP: RELEASE=RESTORED FRAMES=UNCHANGED");
    Ok(())
}