//! Live parse-only gate for bounded ELF64 program headers. No file bytes are
//! installed in a UserSpace and no ELF entry is executed by this image.
use super::*;
use turkos_kernel::elf::{self, Error};

fn fail(reason: &str) -> ! {
    write_str("TURKOS/ELF-LAYOUT-ERROR: ");
    write_line(reason);
    park()
}

fn fixture() -> [u8; 124] {
    let mut bytes = [0u8; 124];
    bytes[..20].copy_from_slice(&[
        0x7f, b'E', b'L', b'F', 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0xb7, 0,
    ]);
    bytes[16..18].copy_from_slice(&2u16.to_le_bytes());
    bytes[20..24].copy_from_slice(&1u32.to_le_bytes());
    bytes[24..32].copy_from_slice(&mmu::USER_CODE_VA.to_le_bytes());
    bytes[32..40].copy_from_slice(&64u64.to_le_bytes());
    bytes[52..54].copy_from_slice(&64u16.to_le_bytes());
    bytes[54..56].copy_from_slice(&56u16.to_le_bytes());
    bytes[56..58].copy_from_slice(&1u16.to_le_bytes());
    bytes[64..68].copy_from_slice(&1u32.to_le_bytes());
    bytes[68..72].copy_from_slice(&5u32.to_le_bytes());
    bytes[72..80].copy_from_slice(&120u64.to_le_bytes());
    bytes[80..88].copy_from_slice(&mmu::USER_CODE_VA.to_le_bytes());
    bytes[96..104].copy_from_slice(&4u64.to_le_bytes());
    bytes[104..112].copy_from_slice(&4u64.to_le_bytes());
    bytes[112..120].copy_from_slice(&1u64.to_le_bytes());
    bytes[120..124].copy_from_slice(b"CODE");
    bytes
}

pub(super) fn smoke_test() -> ! {
    let good = fixture();
    let layout = elf::parse_layout(&good).unwrap_or_else(|_| fail("valid static layout"));
    let Some(segment) = layout.segments[0] else {
        fail("missing load segment");
    };
    if layout.count != 1
        || layout.entry != mmu::USER_CODE_VA
        || segment.file_offset != 120
        || segment.virtual_address != mmu::USER_CODE_VA
        || segment.file_size != 4
        || segment.memory_size != 4
        || segment.flags != 5
    {
        fail("layout fields");
    }
    write_str("TURKOS/ELF-LAYOUT-ACCEPT: COUNT=0x");
    write_hex(layout.count);
    write_str(" ENTRY=0x");
    write_hex(layout.entry as usize);
    write_str(" FILE=0x");
    write_hex(segment.file_size as usize);
    write_str(" MEM=0x");
    write_hex(segment.memory_size as usize);
    write_str(" FLAGS=0x");
    write_hex(segment.flags as usize);
    write_str("\r\n");

    let mut bad = good;
    bad[56..58].copy_from_slice(&5u16.to_le_bytes());
    if elf::parse_layout(&bad) != Err(Error::BadProgramCount) {
        fail("PHDR count");
    }
    write_line("TURKOS/ELF-LAYOUT-COUNT: REJECT");
    bad = good;
    bad[32..40].copy_from_slice(&u64::MAX.to_le_bytes());
    if elf::parse_layout(&bad) != Err(Error::BadProgramTable) {
        fail("PHDR table range");
    }
    write_line("TURKOS/ELF-LAYOUT-TABLE: REJECT");
    bad = good;
    bad[72..80].copy_from_slice(&u64::MAX.to_le_bytes());
    if elf::parse_layout(&bad) != Err(Error::BadFileRange) {
        fail("file range overflow");
    }
    write_line("TURKOS/ELF-LAYOUT-FILE: REJECT");
    bad = good;
    bad[104..112].copy_from_slice(&3u64.to_le_bytes());
    if elf::parse_layout(&bad) != Err(Error::FileLargerThanMemory) {
        fail("filesz > memsz");
    }
    write_line("TURKOS/ELF-LAYOUT-MEM: REJECT");
    bad = good;
    bad[80..88].copy_from_slice(&0x4000_0000u64.to_le_bytes());
    if elf::parse_layout(&bad) != Err(Error::BadUserAddress) {
        fail("kernel virtual address");
    }
    write_line("TURKOS/ELF-LAYOUT-VA: REJECT");
    bad = good;
    bad[68..72].copy_from_slice(&7u32.to_le_bytes());
    if elf::parse_layout(&bad) != Err(Error::WritableExecutable) {
        fail("W+X segment");
    }
    write_line("TURKOS/ELF-LAYOUT-WX: REJECT");
    write_line("TURKOS/ELF-LAYOUT: PASS");
    park()
}