// Copyright 2018 The Chromium OS Authors. All rights reserved.

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE-BSD-3-Clause file.

//

// SPDX-License-Identifier: Apache-2.0 AND BSD-3-Clause

#![no_main]

use std::ffi;

use std::fs::File;

use std::io::{self, Cursor, Read, Seek, SeekFrom, Write};

use std::mem::size_of;

use std::os::unix::io::{FromRawFd, RawFd};

use block::qcow::{QcowFile, RawFile};

use libfuzzer_sys::{fuzz_target, Corpus};

// Take the first 64 bits of data as an address and the next 64 bits as data to

// store there. The rest of the data is used as a qcow image.

fuzz_target!(|bytes: &[u8]| -> Corpus {

    if bytes.len() < 16 {

        // Need an address and data, each are 8 bytes.

        return Corpus::Reject;

    }

    let mut disk_image = Cursor::new(bytes);

    let addr = read_u64(&mut disk_image);

    let value = read_u64(&mut disk_image);

    let shm = memfd_create(&ffi::CString::new("fuzz").unwrap(), 0).unwrap();

    let mut disk_file: File = unsafe { File::from_raw_fd(shm) };

    disk_file.write_all(&bytes[16..]).unwrap();

    disk_file.seek(SeekFrom::Start(0)).unwrap();

    if let Ok(mut qcow) = QcowFile::from(RawFile::new(disk_file, false)) {

        if qcow.seek(SeekFrom::Start(addr)).is_ok() {

            let _ = qcow.write_all(&value.to_le_bytes());

        }

    }

    Corpus::Keep

});

fn read_u64<T: Read>(readable: &mut T) -> u64 {

    let mut buf = [0u8; size_of::<u64>()];

    readable.read_exact(&mut buf[..]).unwrap();

    u64::from_le_bytes(buf)

}

fn memfd_create(name: &ffi::CStr, flags: u32) -> Result<RawFd, io::Error> {

    let res = unsafe { libc::syscall(libc::SYS_memfd_create, name.as_ptr(), flags) };

    if res < 0 {

        Err(io::Error::last_os_error())

    } else {

        Ok(res as RawFd)

    }

}