//! Three-level bounded directory walk and cycle rejection guest probe.

use super::*;
use os_turkfs_directory::{Directory, Error, Kind, Node, NAME_BYTES};

fn node(inode: u64, parent: u64, kind: Kind, name: &[u8]) -> Node {
    let mut bytes = [0; NAME_BYTES];
    bytes[..name.len()].copy_from_slice(name);
    Node {inode, parent, kind, name_len: name.len() as u8, name: bytes}
}

fn tree() -> [Node; 4] {
    [node(1, 0, Kind::Directory, b""),
     node(2, 1, Kind::Directory, b"a"),
     node(3, 2, Kind::Directory, b"b"),
     node(4, 3, Kind::Regular, b"file")]
}

pub fn run(allocator: &mut memory::FrameAllocator) -> Result<(), &'static str> {
    let frames_before = allocator.remaining_pages();
    let directory = Directory::validate(tree()).map_err(|_| "k1620-valid")?;
    if directory.node_count() != 4
        || directory.lookup(b"/a/b/file").map(|node| node.inode) != Ok(4)
        || directory.lookup(b"/a/b").map(|node| node.kind) != Ok(Kind::Directory)
        || directory.lookup(b"/a/b/file/child") != Err(Error::NotDirectory) {
        return Err("k1620-walk");
    }
    write_line("TURKOS/OS/K1620-DIR: ROOT-A-B-FILE=4");

    let mut self_loop = tree();
    self_loop[2].parent = 3;
    if Directory::validate(self_loop) != Err(Error::Loop) {
        return Err("k1620-self-loop");
    }
    write_line("TURKOS/OS/K1620-DIR: SELF-LOOP=REJECTED");

    let mut mutual_loop = tree();
    mutual_loop[1].parent = 3;
    if Directory::validate(mutual_loop) != Err(Error::Loop) {
        return Err("k1620-mutual-loop");
    }
    write_line("TURKOS/OS/K1620-DIR: MUTUAL-LOOP=REJECTED");

    let mut bad_type = tree();
    bad_type[1].kind = Kind::Regular;
    if Directory::validate(bad_type) != Err(Error::NotDirectory)
        || allocator.remaining_pages() != frames_before {
        return Err("k1620-type");
    }
    write_line("TURKOS/OS/K1620-DIR: TYPE=REJECTED FRAMES=UNCHANGED");
    Ok(())
}