//! Two-link traversal and bounded loop refusal in the product kernel.

use super::*;
use os_vfs_paths::{Error as PathError, Mount, MountNamespace, PathState};
use os_vfs_symlink::{Error as LinkError, Link, SymlinkTable};

fn namespace() -> Result<MountNamespace, &'static str> {
    let resolver = PathState::new();
    let root = resolver.resolve(b"/sandbox").map_err(|_| "k1560-root")?;
    let first = Mount::new(resolver.resolve(b"/sandbox/veri")
        .map_err(|_| "k1560-first-path")?, 1).map_err(|_| "k1560-first-mount")?;
    let second = Mount::new(resolver.resolve(b"/sandbox/ara")
        .map_err(|_| "k1560-second-path")?, 2).map_err(|_| "k1560-second-mount")?;
    MountNamespace::new(root, first, second).map_err(|_| "k1560-namespace")
}

pub fn run(allocator: &mut memory::FrameAllocator) -> Result<(), &'static str> {
    let frames_before = allocator.remaining_pages();
    let namespace = namespace()?;
    let first_link = Link::new(&namespace, b"/veri/kisa", b"/ara/ikinci")
        .map_err(|_| "k1560-first-link")?;
    let second_link = Link::new(&namespace, b"/ara/ikinci", b"/ara/dosya")
        .map_err(|_| "k1560-second-link")?;
    let table = SymlinkTable::new(first_link, second_link)
        .map_err(|_| "k1560-table")?;
    let result = table.resolve(&namespace, b"/veri/kisa")
        .map_err(|_| "k1560-resolve")?;
    if result.hops != 2 || result.route.volume != 2
        || result.route.path.component(2) != Some("dosya") {
        return Err("k1560-two-hop-result");
    }
    let self_link = Link::new(&namespace, b"/veri/dongu", b"/veri/dongu")
        .map_err(|_| "k1560-self-link")?;
    let loop_table = SymlinkTable::new(self_link, second_link)
        .map_err(|_| "k1560-loop-table")?;
    if loop_table.resolve(&namespace, b"/veri/dongu") != Err(LinkError::Eloop(40))
        || Link::new(&namespace, b"/veri/kisa", b"/../../../disari")
            != Err(LinkError::Path(PathError::AboveRoot))
        || namespace.cwd != namespace.process_root || namespace.generation != 0
        || allocator.remaining_pages() != frames_before {
        return Err("k1560-bounds");
    }
    write_line("TURKOS/OS/K1560-SYMLINK: HOPS=2 VOLUME=2 ELOOP=40 ROOT=REJECTED STATE=UNCHANGED FRAMES=UNCHANGED");
    Ok(())
}