1 files changed, 119 insertions, 0 deletions
diff --git a/src/files.rs b/src/files.rs
new file mode 100644
index 000000000..64160bb84
--- /dev/null
+++ b/src/files.rs
@@ -0,0 +1,119 @@
+// Copyright 2018 the Deno authors. All rights reserved. MIT license.
+
+use futures;
+use futures::Poll;
+use std;
+use std::collections::HashMap;
+use std::io::Error;
+use std::io::{Read, Write};
+use std::sync::atomic::AtomicIsize;
+use std::sync::atomic::Ordering;
+use std::sync::Mutex;
+use tokio;
+use tokio::io::{AsyncRead, AsyncWrite};
+
+// These store Deno's file descriptors. These are not necessarally the operating
+// system ones.
+type FdTable = HashMap<i32, Repr>;
+
+lazy_static! {
+  // Starts at 3 because stdio is [0-2].
+  static ref NEXT_FD: AtomicIsize = AtomicIsize::new(3);
+  static ref FD_TABLE: Mutex<FdTable> = Mutex::new({
+    let mut m = HashMap::new();
+    // TODO Load these lazily during lookup?
+    m.insert(0, Repr::Stdin(tokio::io::stdin()));
+    m.insert(1, Repr::Stdout(tokio::io::stdout()));
+    m.insert(2, Repr::Stderr(tokio::io::stderr()));
+    m
+  });
+}
+
+// Internal representation of DFile.
+enum Repr {
+  Stdin(tokio::io::Stdin),
+  Stdout(tokio::io::Stdout),
+  Stderr(tokio::io::Stderr),
+  FsFile(tokio::fs::File),
+}
+
+// Abstract async file interface.
+// fd does not necessarally correspond to an OS fd.
+// Ideally in unix, if DFile represents an OS fd, it will be the same.
+pub struct DFile {
+  pub fd: i32,
+}
+
+impl Read for DFile {
+  fn read(&mut self, _buf: &mut [u8]) -> std::io::Result<usize> {
+    unimplemented!();
+  }
+}
+
+impl AsyncRead for DFile {
+  fn poll_read(&mut self, buf: &mut [u8]) -> Poll<usize, Error> {
+    let mut table = FD_TABLE.lock().unwrap();
+    let maybe_repr = table.get_mut(&self.fd);
+    match maybe_repr {
+      None => panic!("bad fd"),
+      Some(repr) => match repr {
+        Repr::FsFile(ref mut f) => f.poll_read(buf),
+        Repr::Stdin(ref mut f) => f.poll_read(buf),
+        Repr::Stdout(_) | Repr::Stderr(_) => {
+          panic!("Cannot read from stdout/stderr")
+        }
+      },
+    }
+  }
+}
+
+impl Write for DFile {
+  fn write(&mut self, _buf: &[u8]) -> std::io::Result<usize> {
+    unimplemented!()
+  }
+
+  fn flush(&mut self) -> std::io::Result<()> {
+    unimplemented!()
+  }
+}
+
+impl AsyncWrite for DFile {
+  fn poll_write(&mut self, buf: &[u8]) -> Poll<usize, Error> {
+    let mut table = FD_TABLE.lock().unwrap();
+    let maybe_repr = table.get_mut(&self.fd);
+    match maybe_repr {
+      None => panic!("bad fd"),
+      Some(repr) => match repr {
+        Repr::FsFile(ref mut f) => f.poll_write(buf),
+        Repr::Stdout(ref mut f) => f.poll_write(buf),
+        Repr::Stderr(ref mut f) => f.poll_write(buf),
+        Repr::Stdin(_) => panic!("Cannot write to stdin"),
+      },
+    }
+  }
+
+  fn shutdown(&mut self) -> futures::Poll<(), std::io::Error> {
+    unimplemented!()
+  }
+}
+
+fn new_fd() -> i32 {
+  // TODO If on unix, just extract the real FD of fs_file.
+  // let fd = AsRawFd::as_raw_fd(fs_file.std());
+  let next_fd = NEXT_FD.fetch_add(1, Ordering::SeqCst);
+  next_fd as i32
+}
+
+pub fn add_fs_file(fs_file: tokio::fs::File) -> DFile {
+  let fd = new_fd();
+  let mut tg = FD_TABLE.lock().unwrap();
+  match tg.insert(fd, Repr::FsFile(fs_file)) {
+    Some(_) => panic!("There is already a file with that fd"),
+    None => DFile { fd },
+  }
+}
+
+pub fn lookup(fd: i32) -> Option<DFile> {
+  let table = FD_TABLE.lock().unwrap();
+  table.get(&fd).map(|_| DFile { fd })
+}