From fdac9bd5a362c0e4cc712bb665c91f89491e05fa Mon Sep 17 00:00:00 2001
From: Matteo Collina <hello@matteocollina.com>
Date: Tue, 3 Jul 2018 18:35:59 +0200
Subject: [PATCH] tty: make _read throw ERR_TTY_WRITABLE_NOT_READABLE

This change avoid an 'read ENOTCONN' error introduced by libuv 1.20.0
when trying to read from a TTY WriteStream. Instead, we are throwing
a more actionable ERR_TTY_WRITABLE_NOT_READABLE.

Fixes: https://github.com/nodejs/node/issues/21203
---
 doc/api/errors.md                               |  6 ++++++
 lib/internal/errors.js                          |  3 +++
 lib/tty.js                                      | 13 ++++++++++++-
 .../test-tty-write-stream-resume-crash.js       | 17 +++++++++++++++++
 .../test-tty-write-stream-resume-crash.out      |  0
 5 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 test/pseudo-tty/test-tty-write-stream-resume-crash.js
 create mode 100644 test/pseudo-tty/test-tty-write-stream-resume-crash.out

diff --git a/doc/api/errors.md b/doc/api/errors.md
index 91ec811b2af194..8eee9c9eaf9652 100644
--- a/doc/api/errors.md
+++ b/doc/api/errors.md
@@ -1684,6 +1684,12 @@ A `Transform` stream finished with data still in the write buffer.
 
 The initialization of a TTY failed due to a system error.
 
+<a id="ERR_TTY_WRITABLE_NOT_READABLE"></a>
+### ERR_TTY_WRITABLE_NOT_READABLE
+
+This `Error` is thrown when a read is attempted on a TTY `WriteStream`,
+such as `process.stdout.on('data')`.
+
 <a id="ERR_UNCAUGHT_EXCEPTION_CAPTURE_ALREADY_SET"></a>
 ### ERR_UNCAUGHT_EXCEPTION_CAPTURE_ALREADY_SET
 
diff --git a/lib/internal/errors.js b/lib/internal/errors.js
index 862ec2dbe62b67..2d06f8f9deb96d 100644
--- a/lib/internal/errors.js
+++ b/lib/internal/errors.js
@@ -825,6 +825,9 @@ E('ERR_TRANSFORM_ALREADY_TRANSFORMING',
 E('ERR_TRANSFORM_WITH_LENGTH_0',
   'Calling transform done when writableState.length != 0', Error);
 E('ERR_TTY_INIT_FAILED', 'TTY initialization failed', SystemError);
+E('ERR_TTY_WRITABLE_NOT_READABLE',
+  'The Writable side of a TTY is not Readable',
+  Error);
 E('ERR_UNCAUGHT_EXCEPTION_CAPTURE_ALREADY_SET',
   '`process.setupUncaughtExceptionCapture()` was called while a capture ' +
     'callback was already active',
diff --git a/lib/tty.js b/lib/tty.js
index b36adf2534c326..5e0e528c7e4593 100644
--- a/lib/tty.js
+++ b/lib/tty.js
@@ -25,7 +25,11 @@ const { inherits, _extend } = require('util');
 const net = require('net');
 const { TTY, isTTY } = process.binding('tty_wrap');
 const errors = require('internal/errors');
-const { ERR_INVALID_FD, ERR_TTY_INIT_FAILED } = errors.codes;
+const {
+  ERR_INVALID_FD,
+  ERR_TTY_INIT_FAILED,
+  ERR_TTY_WRITABLE_NOT_READABLE
+} = errors.codes;
 const { getColorDepth } = require('internal/tty');
 
 // Lazy loaded for startup performance.
@@ -122,6 +126,13 @@ WriteStream.prototype._refreshSize = function() {
   }
 };
 
+// A WriteStream is not readable from, so _read become a no-op.
+// this method could still be called because net.Socket()
+// is a duplex
+WriteStream.prototype._read = function() {
+  this.destroy(new ERR_TTY_WRITABLE_NOT_READABLE());
+};
+
 // Backwards-compat
 WriteStream.prototype.cursorTo = function(x, y) {
   if (readline === undefined) readline = require('readline');
diff --git a/test/pseudo-tty/test-tty-write-stream-resume-crash.js b/test/pseudo-tty/test-tty-write-stream-resume-crash.js
new file mode 100644
index 00000000000000..12ec1df45ad598
--- /dev/null
+++ b/test/pseudo-tty/test-tty-write-stream-resume-crash.js
@@ -0,0 +1,17 @@
+'use strict';
+
+const common = require('../common');
+const { WriteStream } = require('tty');
+const fd = common.getTTYfd();
+
+// Calling resume on a tty.WriteStream should be a no-op
+// Ref: https://github.com/nodejs/node/issues/21203
+
+const stream = new WriteStream(fd);
+stream.resume();
+
+stream.on('error', common.expectsError({
+  code: 'ERR_TTY_WRITABLE_NOT_READABLE',
+  type: Error,
+  message: 'The Writable side of a TTY is not Readable'
+}));
diff --git a/test/pseudo-tty/test-tty-write-stream-resume-crash.out b/test/pseudo-tty/test-tty-write-stream-resume-crash.out
new file mode 100644
index 00000000000000..e69de29bb2d1d6