denoland-deno/src/handlers.rs

// Copyright 2018 the Deno authors. All rights reserved. MIT license.

use errors;
use errors::DenoError;
use errors::DenoResult;
use fs as deno_fs;
use isolate::Buf;
use isolate::IsolateState;
use isolate::Op;
use msg;

use files;
use flatbuffers::FlatBufferBuilder;
use futures;
use futures::future::poll_fn;
use futures::sync::oneshot;
use futures::Poll;
use hyper;
use hyper::rt::{Future, Stream};
use hyper::Client;
use remove_dir_all::remove_dir_all;
use std;
use std::fs;
#[cfg(any(unix))]
use std::os::unix::fs::PermissionsExt;
use std::path::Path;
use std::path::PathBuf;
use std::sync::Arc;
use std::time::UNIX_EPOCH;
use std::time::{Duration, Instant};
use tokio;
use tokio::timer::Delay;
use tokio_io::AsyncRead;
use tokio_io::AsyncWrite;
use tokio_threadpool;

type OpResult = DenoResult<Buf>;

// TODO Ideally we wouldn't have to box the Op being returned.
// The box is just to make it easier to get a prototype refactor working.
type Handler =
  fn(state: Arc<IsolateState>, base: &msg::Base, data: &'static mut [u8])
    -> Box<Op>;

// Hopefully Rust optimizes this away.
fn empty_buf() -> Buf {
  Box::new([])
}

pub fn msg_from_js(
  state: Arc<IsolateState>,
  control: &[u8],
  data: &'static mut [u8],
) -> (bool, Box<Op>) {
  let base = msg::get_root_as_base(control);
  let is_sync = base.sync();
  let msg_type = base.msg_type();
  let cmd_id = base.cmd_id();
  let handler: Handler = match msg_type {
    msg::Any::Start => handle_start,
    msg::Any::CodeFetch => handle_code_fetch,
    msg::Any::CodeCache => handle_code_cache,
    msg::Any::SetTimeout => handle_set_timeout,
    msg::Any::Environ => handle_env,
    msg::Any::FetchReq => handle_fetch_req,
    msg::Any::TimerStart => handle_timer_start,
    msg::Any::TimerClear => handle_timer_clear,
    msg::Any::MakeTempDir => handle_make_temp_dir,
    msg::Any::Mkdir => handle_mkdir,
    msg::Any::Open => handle_open,
    msg::Any::Read => handle_read,
    msg::Any::Write => handle_write,
    msg::Any::Remove => handle_remove,
    msg::Any::ReadFile => handle_read_file,
    msg::Any::Rename => handle_rename,
    msg::Any::Readlink => handle_read_link,
    msg::Any::Symlink => handle_symlink,
    msg::Any::SetEnv => handle_set_env,
    msg::Any::Stat => handle_stat,
    msg::Any::Truncate => handle_truncate,
    msg::Any::WriteFile => handle_write_file,
    msg::Any::Exit => handle_exit,
    msg::Any::CopyFile => handle_copy_file,
    _ => panic!(format!(
      "Unhandled message {}",
      msg::enum_name_any(msg_type)
    )),
  };

  let op: Box<Op> = handler(state.clone(), &base, data);
  let boxed_op = Box::new(
    op.or_else(move |err: DenoError| -> DenoResult<Buf> {
      debug!("op err {}", err);
      // No matter whether we got an Err or Ok, we want a serialized message to
      // send back. So transform the DenoError into a deno_buf.
      let builder = &mut FlatBufferBuilder::new();
      let errmsg_offset = builder.create_string(&format!("{}", err));
      Ok(serialize_response(
        cmd_id,
        builder,
        msg::BaseArgs {
          error: Some(errmsg_offset),
          error_kind: err.kind(),
          ..Default::default()
        },
      ))
    }).and_then(move |buf: Buf| -> DenoResult<Buf> {
      // Handle empty responses. For sync responses we just want
      // to send null. For async we want to send a small message
      // with the cmd_id.
      let buf = if is_sync || buf.len() > 0 {
        buf
      } else {
        let builder = &mut FlatBufferBuilder::new();
        serialize_response(
          cmd_id,
          builder,
          msg::BaseArgs {
            ..Default::default()
          },
        )
      };
      Ok(buf)
    }),
  );

  debug!(
    "msg_from_js {} sync {}",
    msg::enum_name_any(msg_type),
    base.sync()
  );
  return (base.sync(), boxed_op);
}

fn permission_denied() -> DenoError {
  DenoError::from(std::io::Error::new(
    std::io::ErrorKind::PermissionDenied,
    "permission denied",
  ))
}

fn not_implemented() -> DenoError {
  DenoError::from(std::io::Error::new(
    std::io::ErrorKind::Other,
    "Not implemented",
  ))
}

fn handle_exit(
  _config: Arc<IsolateState>,
  base: &msg::Base,
  _data: &'static mut [u8],
) -> Box<Op> {
  let msg = base.msg_as_exit().unwrap();
  std::process::exit(msg.code())
}

fn handle_start(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let mut builder = FlatBufferBuilder::new();

  let argv = state.argv.iter().map(|s| s.as_str()).collect::<Vec<_>>();
  let argv_off = builder.create_vector_of_strings(argv.as_slice());

  let cwd_path = std::env::current_dir().unwrap();
  let cwd_off =
    builder.create_string(deno_fs::normalize_path(cwd_path.as_ref()).as_ref());

  let msg = msg::StartRes::create(
    &mut builder,
    &msg::StartResArgs {
      cwd: Some(cwd_off),
      argv: Some(argv_off),
      debug_flag: state.flags.log_debug,
      recompile_flag: state.flags.recompile,
      ..Default::default()
    },
  );

  ok_future(serialize_response(
    base.cmd_id(),
    &mut builder,
    msg::BaseArgs {
      msg_type: msg::Any::StartRes,
      msg: Some(msg.as_union_value()),
      ..Default::default()
    },
  ))
}

fn serialize_response(
  cmd_id: u32,
  builder: &mut FlatBufferBuilder,
  mut args: msg::BaseArgs,
) -> Buf {
  args.cmd_id = cmd_id;
  let base = msg::Base::create(builder, &args);
  msg::finish_base_buffer(builder, base);
  let data = builder.finished_data();
  // println!("serialize_response {:x?}", data);
  let vec = data.to_vec();
  vec.into_boxed_slice()
}

fn ok_future(buf: Buf) -> Box<Op> {
  Box::new(futures::future::ok(buf))
}

// Shout out to Earl Sweatshirt.
fn odd_future(err: DenoError) -> Box<Op> {
  Box::new(futures::future::err(err))
}

// https://github.com/denoland/isolate/blob/golang/os.go#L100-L154
fn handle_code_fetch(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let msg = base.msg_as_code_fetch().unwrap();
  let cmd_id = base.cmd_id();
  let module_specifier = msg.module_specifier().unwrap();
  let containing_file = msg.containing_file().unwrap();

  assert_eq!(state.dir.root.join("gen"), state.dir.gen, "Sanity check");

  Box::new(futures::future::result(|| -> OpResult {
    let builder = &mut FlatBufferBuilder::new();
    let out = state.dir.code_fetch(module_specifier, containing_file)?;
    let mut msg_args = msg::CodeFetchResArgs {
      module_name: Some(builder.create_string(&out.module_name)),
      filename: Some(builder.create_string(&out.filename)),
      source_code: Some(builder.create_string(&out.source_code)),
      ..Default::default()
    };
    match out.maybe_output_code {
      Some(ref output_code) => {
        msg_args.output_code = Some(builder.create_string(output_code));
      }
      _ => (),
    };
    let msg = msg::CodeFetchRes::create(builder, &msg_args);
    Ok(serialize_response(
      cmd_id,
      builder,
      msg::BaseArgs {
        msg: Some(msg.as_union_value()),
        msg_type: msg::Any::CodeFetchRes,
        ..Default::default()
      },
    ))
  }()))
}

// https://github.com/denoland/isolate/blob/golang/os.go#L156-L169
fn handle_code_cache(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let msg = base.msg_as_code_cache().unwrap();
  let filename = msg.filename().unwrap();
  let source_code = msg.source_code().unwrap();
  let output_code = msg.output_code().unwrap();
  Box::new(futures::future::result(|| -> OpResult {
    state.dir.code_cache(filename, source_code, output_code)?;
    Ok(empty_buf())
  }()))
}

fn handle_set_timeout(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let msg = base.msg_as_set_timeout().unwrap();
  let val = msg.timeout() as isize;
  state
    .timeout
    .swap(val, std::sync::atomic::Ordering::Relaxed);
  ok_future(empty_buf())
}

fn handle_set_env(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let msg = base.msg_as_set_env().unwrap();
  let key = msg.key().unwrap();
  let value = msg.value().unwrap();

  if !state.flags.allow_env {
    return odd_future(permission_denied());
  }

  std::env::set_var(key, value);
  ok_future(empty_buf())
}

fn handle_env(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let cmd_id = base.cmd_id();

  if !state.flags.allow_env {
    return odd_future(permission_denied());
  }

  let builder = &mut FlatBufferBuilder::new();
  let vars: Vec<_> = std::env::vars()
    .map(|(key, value)| {
      let key = builder.create_string(&key);
      let value = builder.create_string(&value);

      msg::EnvPair::create(
        builder,
        &msg::EnvPairArgs {
          key: Some(key),
          value: Some(value),
          ..Default::default()
        },
      )
    }).collect();
  let tables = builder.create_vector(&vars);
  let msg = msg::EnvironRes::create(
    builder,
    &msg::EnvironResArgs {
      map: Some(tables),
      ..Default::default()
    },
  );
  ok_future(serialize_response(
    cmd_id,
    builder,
    msg::BaseArgs {
      msg: Some(msg.as_union_value()),
      msg_type: msg::Any::EnvironRes,
      ..Default::default()
    },
  ))
}

fn handle_fetch_req(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let msg = base.msg_as_fetch_req().unwrap();
  let cmd_id = base.cmd_id();
  let id = msg.id();
  let url = msg.url().unwrap();

  if !state.flags.allow_net {
    return odd_future(permission_denied());
  }

  let url = url.parse::<hyper::Uri>().unwrap();
  let client = Client::new();

  debug!("Before fetch {}", url);
  let future = client.get(url).and_then(move |res| {
    let status = res.status().as_u16() as i32;
    debug!("fetch {}", status);

    let headers = {
      let map = res.headers();
      let keys = map
        .keys()
        .map(|s| s.as_str().to_string())
        .collect::<Vec<_>>();
      let values = map
        .values()
        .map(|s| s.to_str().unwrap().to_string())
        .collect::<Vec<_>>();
      (keys, values)
    };

    // TODO Handle streaming body.
    res
      .into_body()
      .concat2()
      .map(move |body| (status, body, headers))
  });

  let future = future.map_err(|err| -> DenoError { err.into() }).and_then(
    move |(status, body, headers)| {
      debug!("fetch body ");
      let builder = &mut FlatBufferBuilder::new();
      // Send the first message without a body. This is just to indicate
      // what status code.
      let body_off = builder.create_vector(body.as_ref());
      let header_keys: Vec<&str> = headers.0.iter().map(|s| &**s).collect();
      let header_keys_off =
        builder.create_vector_of_strings(header_keys.as_slice());
      let header_values: Vec<&str> = headers.1.iter().map(|s| &**s).collect();
      let header_values_off =
        builder.create_vector_of_strings(header_values.as_slice());

      let msg = msg::FetchRes::create(
        builder,
        &msg::FetchResArgs {
          id,
          status,
          body: Some(body_off),
          header_key: Some(header_keys_off),
          header_value: Some(header_values_off),
          ..Default::default()
        },
      );

      Ok(serialize_response(
        cmd_id,
        builder,
        msg::BaseArgs {
          msg: Some(msg.as_union_value()),
          msg_type: msg::Any::FetchRes,
          ..Default::default()
        },
      ))
    },
  );
  Box::new(future)
}

fn set_timeout<F>(
  cb: F,
  delay: u32,
) -> (
  impl Future<Item = (), Error = ()>,
  futures::sync::oneshot::Sender<()>,
)
where
  F: FnOnce() -> (),
{
  let (cancel_tx, cancel_rx) = oneshot::channel::<()>();
  let when = Instant::now() + Duration::from_millis(delay.into());
  let delay_task = Delay::new(when)
    .map_err(|e| panic!("timer failed; err={:?}", e))
    .and_then(|_| {
      cb();
      Ok(())
    }).select(cancel_rx)
    .map(|_| ())
    .map_err(|_| ());

  (delay_task, cancel_tx)
}

// This is just type conversion. Implement From trait?
// See https://github.com/tokio-rs/tokio/blob/ffd73a64e7ec497622b7f939e38017afe7124dc4/tokio-fs/src/lib.rs#L76-L85
fn convert_blocking<F>(f: F) -> Poll<Buf, DenoError>
where
  F: FnOnce() -> DenoResult<Buf>,
{
  use futures::Async::*;
  match tokio_threadpool::blocking(f) {
    Ok(Ready(Ok(v))) => Ok(v.into()),
    Ok(Ready(Err(err))) => Err(err),
    Ok(NotReady) => Ok(NotReady),
    Err(_) => panic!("blocking error"),
  }
}

// TODO Do not use macro for the blocking function.. We should instead be able
// to do this with a normal function, but there seems to some type system
// issues. The type of this function should be something like this:
//   fn blocking<F>(is_sync: bool, f: F) -> Box<Op>
//   where F: FnOnce() -> DenoResult<Buf>
macro_rules! blocking {
  ($is_sync:expr,$fn:expr) => {
    if $is_sync {
      // If synchronous, execute the function immediately on the main thread.
      Box::new(futures::future::result($fn()))
    } else {
      // Otherwise dispatch to thread pool.
      Box::new(poll_fn(move || convert_blocking($fn)))
    }
  };
}

fn handle_make_temp_dir(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let base = Box::new(*base);
  let msg = base.msg_as_make_temp_dir().unwrap();
  let cmd_id = base.cmd_id();

  if !state.flags.allow_write {
    return odd_future(permission_denied());
  }

  let dir = msg.dir().map(PathBuf::from);
  let prefix = msg.prefix().map(String::from);
  let suffix = msg.suffix().map(String::from);

  blocking!(base.sync(), || -> OpResult {
    // TODO(piscisaureus): use byte vector for paths, not a string.
    // See https://github.com/denoland/isolate/issues/627.
    // We can't assume that paths are always valid utf8 strings.
    let path = deno_fs::make_temp_dir(
      // Converting Option<String> to Option<&str>
      dir.as_ref().map(|x| &**x),
      prefix.as_ref().map(|x| &**x),
      suffix.as_ref().map(|x| &**x),
    )?;
    let builder = &mut FlatBufferBuilder::new();
    let path_off = builder.create_string(path.to_str().unwrap());
    let msg = msg::MakeTempDirRes::create(
      builder,
      &msg::MakeTempDirResArgs {
        path: Some(path_off),
        ..Default::default()
      },
    );
    Ok(serialize_response(
      cmd_id,
      builder,
      msg::BaseArgs {
        msg: Some(msg.as_union_value()),
        msg_type: msg::Any::MakeTempDirRes,
        ..Default::default()
      },
    ))
  })
}

fn handle_mkdir(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let msg = base.msg_as_mkdir().unwrap();
  let mode = msg.mode();
  let path = String::from(msg.path().unwrap());

  if !state.flags.allow_write {
    return odd_future(permission_denied());
  }

  blocking!(base.sync(), || {
    debug!("handle_mkdir {}", path);
    deno_fs::mkdir(Path::new(&path), mode)?;
    Ok(empty_buf())
  })
}

fn handle_open(
  _state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let cmd_id = base.cmd_id();
  let msg = base.msg_as_open().unwrap();
  let filename = PathBuf::from(msg.filename().unwrap());
  // TODO let perm = msg.perm();

  let op = tokio::fs::File::open(filename)
    .map_err(|err| DenoError::from(err))
    .and_then(move |fs_file| -> OpResult {
      let dfile = files::add_fs_file(fs_file);
      let builder = &mut FlatBufferBuilder::new();
      let msg = msg::OpenRes::create(
        builder,
        &msg::OpenResArgs {
          fd: dfile.fd,
          ..Default::default()
        },
      );
      Ok(serialize_response(
        cmd_id,
        builder,
        msg::BaseArgs {
          msg: Some(msg.as_union_value()),
          msg_type: msg::Any::OpenRes,
          ..Default::default()
        },
      ))
    });
  Box::new(op)
}

fn handle_read(
  _state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  let cmd_id = base.cmd_id();
  let msg = base.msg_as_read().unwrap();
  let fd = msg.fd();

  match files::lookup(fd) {
    None => odd_future(errors::new(
      errors::ErrorKind::BadFileDescriptor,
      String::from("Bad File Descriptor"),
    )),
    Some(mut dfile) => {
      let op = futures::future::poll_fn(move || {
        let poll = dfile.poll_read(data);
        poll
      }).map_err(|err| DenoError::from(err))
      .and_then(move |nread: usize| {
        let builder = &mut FlatBufferBuilder::new();
        let msg = msg::ReadRes::create(
          builder,
          &msg::ReadResArgs {
            nread: nread as u32,
            eof: nread == 0,
            ..Default::default()
          },
        );
        Ok(serialize_response(
          cmd_id,
          builder,
          msg::BaseArgs {
            msg: Some(msg.as_union_value()),
            msg_type: msg::Any::ReadRes,
            ..Default::default()
          },
        ))
      });
      Box::new(op)
    }
  }
}

fn handle_write(
  _state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  let cmd_id = base.cmd_id();
  let msg = base.msg_as_write().unwrap();
  let fd = msg.fd();

  match files::lookup(fd) {
    None => odd_future(errors::new(
      errors::ErrorKind::BadFileDescriptor,
      String::from("Bad File Descriptor"),
    )),
    Some(mut dfile) => {
      let op = futures::future::poll_fn(move || {
        let poll = dfile.poll_write(data);
        poll
      }).map_err(|err| DenoError::from(err))
      .and_then(move |bytes_written: usize| {
        let builder = &mut FlatBufferBuilder::new();
        let msg = msg::WriteRes::create(
          builder,
          &msg::WriteResArgs {
            nbyte: bytes_written as u32,
            ..Default::default()
          },
        );
        Ok(serialize_response(
          cmd_id,
          builder,
          msg::BaseArgs {
            msg: Some(msg.as_union_value()),
            msg_type: msg::Any::WriteRes,
            ..Default::default()
          },
        ))
      });
      Box::new(op)
    }
  }
}

fn handle_remove(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let msg = base.msg_as_remove().unwrap();
  let path = PathBuf::from(msg.path().unwrap());
  let recursive = msg.recursive();
  if !state.flags.allow_write {
    return odd_future(permission_denied());
  }
  blocking!(base.sync(), || {
    debug!("handle_remove {}", path.display());
    let metadata = fs::metadata(&path)?;
    if metadata.is_file() {
      fs::remove_file(&path)?;
    } else {
      if recursive {
        remove_dir_all(&path)?;
      } else {
        fs::remove_dir(&path)?;
      }
    }
    Ok(empty_buf())
  })
}

// Prototype https://github.com/denoland/isolate/blob/golang/os.go#L171-L184
fn handle_read_file(
  _config: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let msg = base.msg_as_read_file().unwrap();
  let cmd_id = base.cmd_id();
  let filename = PathBuf::from(msg.filename().unwrap());
  debug!("handle_read_file {}", filename.display());
  blocking!(base.sync(), || {
    let vec = fs::read(&filename)?;
    // Build the response message. memcpy data into msg.
    // TODO(ry) zero-copy.
    let builder = &mut FlatBufferBuilder::new();
    let data_off = builder.create_vector(vec.as_slice());
    let msg = msg::ReadFileRes::create(
      builder,
      &msg::ReadFileResArgs {
        data: Some(data_off),
        ..Default::default()
      },
    );
    Ok(serialize_response(
      cmd_id,
      builder,
      msg::BaseArgs {
        msg: Some(msg.as_union_value()),
        msg_type: msg::Any::ReadFileRes,
        ..Default::default()
      },
    ))
  })
}

fn handle_copy_file(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let msg = base.msg_as_copy_file().unwrap();
  let from = PathBuf::from(msg.from().unwrap());
  let to = PathBuf::from(msg.to().unwrap());

  if !state.flags.allow_write {
    return odd_future(permission_denied());
  }

  debug!("handle_copy_file {} {}", from.display(), to.display());
  blocking!(base.sync(), || {
    fs::copy(&from, &to)?;
    Ok(empty_buf())
  })
}

macro_rules! to_seconds {
  ($time:expr) => {{
    // Unwrap is safe here as if the file is before the unix epoch
    // something is very wrong.
    $time
      .and_then(|t| Ok(t.duration_since(UNIX_EPOCH).unwrap().as_secs()))
      .unwrap_or(0)
  }};
}

#[cfg(any(unix))]
fn get_mode(perm: fs::Permissions) -> u32 {
  perm.mode()
}

#[cfg(not(any(unix)))]
fn get_mode(_perm: fs::Permissions) -> u32 {
  0
}

fn handle_stat(
  _config: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let msg = base.msg_as_stat().unwrap();
  let cmd_id = base.cmd_id();
  let filename = PathBuf::from(msg.filename().unwrap());
  let lstat = msg.lstat();

  blocking!(base.sync(), || {
    let builder = &mut FlatBufferBuilder::new();
    debug!("handle_stat {} {}", filename.display(), lstat);
    let metadata = if lstat {
      fs::symlink_metadata(&filename)?
    } else {
      fs::metadata(&filename)?
    };

    let msg = msg::StatRes::create(
      builder,
      &msg::StatResArgs {
        is_file: metadata.is_file(),
        is_symlink: metadata.file_type().is_symlink(),
        len: metadata.len(),
        modified: to_seconds!(metadata.modified()),
        accessed: to_seconds!(metadata.accessed()),
        created: to_seconds!(metadata.created()),
        mode: get_mode(metadata.permissions()),
        has_mode: cfg!(target_family = "unix"),
        ..Default::default()
      },
    );

    Ok(serialize_response(
      cmd_id,
      builder,
      msg::BaseArgs {
        msg: Some(msg.as_union_value()),
        msg_type: msg::Any::StatRes,
        ..Default::default()
      },
    ))
  })
}

fn handle_write_file(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  let msg = base.msg_as_write_file().unwrap();

  if !state.flags.allow_write {
    return odd_future(permission_denied());
  }

  let filename = String::from(msg.filename().unwrap());
  let perm = msg.perm();

  blocking!(base.sync(), || -> OpResult {
    debug!("handle_write_file {} {}", filename, data.len());
    deno_fs::write_file(Path::new(&filename), data, perm)?;
    Ok(empty_buf())
  })
}

fn remove_timer(state: Arc<IsolateState>, timer_id: u32) {
  let mut timers = state.timers.lock().unwrap();
  timers.remove(&timer_id);
}

// Prototype: https://github.com/ry/isolate/blob/golang/timers.go#L25-L39
fn handle_timer_start(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  debug!("handle_timer_start");
  let msg = base.msg_as_timer_start().unwrap();
  let cmd_id = base.cmd_id();
  let timer_id = msg.id();
  let delay = msg.delay();

  let config2 = state.clone();
  let future = {
    let (delay_task, cancel_delay) = set_timeout(
      move || {
        remove_timer(config2, timer_id);
      },
      delay,
    );
    let mut timers = state.timers.lock().unwrap();
    timers.insert(timer_id, cancel_delay);
    delay_task
  };
  let r = Box::new(future.then(move |result| {
    let builder = &mut FlatBufferBuilder::new();
    let msg = msg::TimerReady::create(
      builder,
      &msg::TimerReadyArgs {
        id: timer_id,
        canceled: result.is_err(),
        ..Default::default()
      },
    );
    Ok(serialize_response(
      cmd_id,
      builder,
      msg::BaseArgs {
        msg: Some(msg.as_union_value()),
        msg_type: msg::Any::TimerReady,
        ..Default::default()
      },
    ))
  }));
  r
}

// Prototype: https://github.com/ry/isolate/blob/golang/timers.go#L40-L43
fn handle_timer_clear(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let msg = base.msg_as_timer_clear().unwrap();
  debug!("handle_timer_clear");
  remove_timer(state, msg.id());
  ok_future(empty_buf())
}

fn handle_rename(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  if !state.flags.allow_write {
    return odd_future(permission_denied());
  }
  let msg = base.msg_as_rename().unwrap();
  let oldpath = PathBuf::from(msg.oldpath().unwrap());
  let newpath = PathBuf::from(msg.newpath().unwrap());
  blocking!(base.sync(), || -> OpResult {
    debug!("handle_rename {} {}", oldpath.display(), newpath.display());
    fs::rename(&oldpath, &newpath)?;
    Ok(empty_buf())
  })
}

fn handle_symlink(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  if !state.flags.allow_write {
    return odd_future(permission_denied());
  }
  // TODO Use type for Windows.
  if cfg!(windows) {
    return odd_future(not_implemented());
  }

  let msg = base.msg_as_symlink().unwrap();
  let oldname = PathBuf::from(msg.oldname().unwrap());
  let newname = PathBuf::from(msg.newname().unwrap());
  blocking!(base.sync(), || -> OpResult {
    debug!("handle_symlink {} {}", oldname.display(), newname.display());
    #[cfg(any(unix))]
    std::os::unix::fs::symlink(&oldname, &newname)?;
    Ok(empty_buf())
  })
}

fn handle_read_link(
  _state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);
  let msg = base.msg_as_readlink().unwrap();
  let cmd_id = base.cmd_id();
  let name = PathBuf::from(msg.name().unwrap());

  blocking!(base.sync(), || -> OpResult {
    debug!("handle_read_link {}", name.display());
    let path = fs::read_link(&name)?;
    let builder = &mut FlatBufferBuilder::new();
    let path_off = builder.create_string(path.to_str().unwrap());
    let msg = msg::ReadlinkRes::create(
      builder,
      &msg::ReadlinkResArgs {
        path: Some(path_off),
        ..Default::default()
      },
    );
    Ok(serialize_response(
      cmd_id,
      builder,
      msg::BaseArgs {
        msg: Some(msg.as_union_value()),
        msg_type: msg::Any::ReadlinkRes,
        ..Default::default()
      },
    ))
  })
}

fn handle_truncate(
  state: Arc<IsolateState>,
  base: &msg::Base,
  data: &'static mut [u8],
) -> Box<Op> {
  assert_eq!(data.len(), 0);

  if !state.flags.allow_write {
    return odd_future(permission_denied());
  }

  let msg = base.msg_as_truncate().unwrap();
  let filename = String::from(msg.name().unwrap());
  let len = msg.len();
  blocking!(base.sync(), || {
    debug!("handle_truncate {} {}", filename, len);
    let f = fs::OpenOptions::new().write(true).open(&filename)?;
    f.set_len(len as u64)?;
    Ok(empty_buf())
  })
}