fix: Deno.readSync on stdin (#6126)

Currently sync operations on stdin are failing because tokio::Stdin
cannot be converted to a std::File.

This commit replaces tokio::stdin with a raw file descriptor 
wrapped in a std::fs::File which can be converted to a 
tokio::File and back again making the synchronous version 
of op_read actually work.

cli/ops/io.rs

@@ -37,6 +37,17 @@ lazy_static! {
   /// resource table is dropped storing reference to that handle, the handle
   /// itself won't be closed (so Deno.core.print) will still work.
   // TODO(ry) It should be possible to close stdout.
+  static ref STDIN_HANDLE: std::fs::File = {
+    #[cfg(not(windows))]
+    let stdin = unsafe { std::fs::File::from_raw_fd(0) };
+    #[cfg(windows)]
+    let stdin = unsafe {
+      std::fs::File::from_raw_handle(winapi::um::processenv::GetStdHandle(
+        winapi::um::winbase::STD_INPUT_HANDLE,
+      ))
+    };
+    stdin
+  };
   static ref STDOUT_HANDLE: std::fs::File = {
     #[cfg(not(windows))]
     let stdout = unsafe { std::fs::File::from_raw_fd(1) };
@@ -71,10 +82,10 @@ pub fn get_stdio() -> (
   StreamResourceHolder,
   StreamResourceHolder,
 ) {
-  let stdin = StreamResourceHolder::new(StreamResource::Stdin(
+  let stdin = StreamResourceHolder::new(StreamResource::FsFile(Some({
-    tokio::io::stdin(),
+    let stdin = STDIN_HANDLE.try_clone().unwrap();
-    TTYMetadata::default(),
+    (tokio::fs::File::from_std(stdin), FileMetadata::default())
-  ));
+  })));
   let stdout = StreamResourceHolder::new(StreamResource::FsFile(Some({
     let stdout = STDOUT_HANDLE.try_clone().unwrap();
     (tokio::fs::File::from_std(stdout), FileMetadata::default())

cli/tests/unit/stdio_test.ts

@@ -0,0 +1,32 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { unitTest, assertEquals } from "./test_util.ts";
+
+unitTest(async function stdioStdinRead() {
+  const nread = await Deno.stdin.read(new Uint8Array(0));
+  assertEquals(nread, 0);
+});
+
+unitTest(function stdioStdinReadSync() {
+  const nread = Deno.stdin.readSync(new Uint8Array(0));
+  assertEquals(nread, 0);
+});
+
+unitTest(async function stdioStdoutWrite() {
+  const nwritten = await Deno.stdout.write(new Uint8Array(0));
+  assertEquals(nwritten, 0);
+});
+
+unitTest(function stdioStdoutWriteSync() {
+  const nwritten = Deno.stdout.writeSync(new Uint8Array(0));
+  assertEquals(nwritten, 0);
+});
+
+unitTest(async function stdioStderrWrite() {
+  const nwritten = await Deno.stderr.write(new Uint8Array(0));
+  assertEquals(nwritten, 0);
+});
+
+unitTest(function stdioStderrWriteSync() {
+  const nwritten = Deno.stderr.writeSync(new Uint8Array(0));
+  assertEquals(nwritten, 0);
+});

cli/tests/unit/unit_tests.ts

@@ -52,6 +52,7 @@ import "./request_test.ts";
 import "./resources_test.ts";
 import "./signal_test.ts";
 import "./stat_test.ts";
+import "./stdio_test.ts";
 import "./streams_internal_test.ts";
 import "./streams_piping_test.ts";
 import "./streams_transform_test.ts";