//! Physical MBR read, bounded primary mount and overlap refusal.

use super::*;
use os_partitions::{Error as PartitionError, MountState};

pub fn run(boot: &BootData,
    allocator: &mut memory::FrameAllocator) -> Result<(), &'static str> {
    let before = allocator.remaining_pages();
    let mut disk = virtio_ro_turkfs::RoDisk::open(
        boot, allocator, "TURKOS/OS/K1525-GET")?;
    if disk.capacity() != 2048 { return Err("k1525-disk-capacity"); }
    let mut sector = [0u8; 512];
    disk.read(0, &mut sector)?;
    disk.close(allocator)?;
    if allocator.remaining_pages() != before {
        return Err("k1525-DMA-leak");
    }
    let mut mounts = MountState::new();
    let table = mounts.mount(&sector, 2048).map_err(|_| "k1525-valid-MBR")?;
    if table.count != 2
        || table.entry(0).map(|part| (part.start_lba, part.end_lba)) != Some((1, 101))
        || table.entry(2).map(|part| (part.start_lba, part.end_lba)) != Some((101, 2048)) {
        return Err("k1525-primary-layout");
    }
    let before_mount = mounts;
    let mut overlap = sector;
    overlap[446 + 2 * 16 + 8..446 + 2 * 16 + 12]
        .copy_from_slice(&100u32.to_le_bytes());
    if mounts.mount(&overlap, 2048) != Err(PartitionError::Overlap)
        || mounts != before_mount {
        return Err("k1525-overlap-changed-mount");
    }
    let mut empty = MountState::new();
    if empty.mount(&overlap, 2048) != Err(PartitionError::Overlap)
        || empty.table.is_some() || empty.generation != 0 {
        return Err("k1525-corrupt-disk-mounted");
    }
    write_line("TURKOS/OS/K1525-MBR: PHYSICAL=READ PRIMARY=2 FIRST=1:101 SECOND=101:2048 OVERLAP=REJECTED MOUNT=UNCHANGED CORRUPT=MOUNT-REFUSED FRAMES=RETURNED");
    Ok(())
}