stream: fix highWaterMark integer overflow

Fixes integer overflows when supplying values exceeding MAX_SAFE_INTEGER
for highWaterMark.

PR-URL: https://github.com/nodejs/node/pull/12593
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Luca Maraschi <luca.maraschi@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

lib/_stream_readable.js

@@ -72,7 +72,7 @@ function ReadableState(options, stream) {
   this.highWaterMark = (hwm || hwm === 0) ? hwm : defaultHwm;
 
   // cast to ints.
-  this.highWaterMark = ~~this.highWaterMark;
+  this.highWaterMark = Math.floor(this.highWaterMark);
 
   // A linked list is used to store data chunks instead of an array because the
   // linked list can remove elements from the beginning faster than

lib/_stream_writable.js

@@ -55,7 +55,7 @@ function WritableState(options, stream) {
   this.highWaterMark = (hwm || hwm === 0) ? hwm : defaultHwm;
 
   // cast to ints.
-  this.highWaterMark = ~~this.highWaterMark;
+  this.highWaterMark = Math.floor(this.highWaterMark);
 
   // drain event flag.
   this.needDrain = false;

test/parallel/test-streams-highwatermark.js

@@ -0,0 +1,18 @@
+'use strict';
+require('../common');
+
+// This test ensures that the stream implementation correctly handles values
+// for highWaterMark which exceed the range of signed 32 bit integers.
+
+const assert = require('assert');
+const stream = require('stream');
+
+// This number exceeds the range of 32 bit integer arithmetic but should still
+// be handled correctly.
+const ovfl = Number.MAX_SAFE_INTEGER;
+
+const readable = stream.Readable({ highWaterMark: ovfl });
+assert.strictEqual(readable._readableState.highWaterMark, ovfl);
+
+const writable = stream.Writable({ highWaterMark: ovfl });
+assert.strictEqual(writable._writableState.highWaterMark, ovfl);