stream: check highWaterMark type and range

Adds checks for the type of "highWaterMark" and restricts it to
non-negative values.

Refs: nodejs#12593

lib/_stream_readable.js

@@ -68,11 +68,21 @@ function ReadableState(options, stream) {
   // the point at which it stops calling _read() to fill the buffer
   // Note: 0 is a valid value, means "don't call _read preemptively ever"
   var hwm = options.highWaterMark;
-  var defaultHwm = this.objectMode ? 16 : 16 * 1024;
-  this.highWaterMark = (hwm || hwm === 0) ? hwm : defaultHwm;
+  if (hwm == null) {
+    var defaultHwm = this.objectMode ? 16 : 16 * 1024;
+    this.highWaterMark = defaultHwm;
+  } else {
+    if (typeof hwm !== 'number') {
+      throw new TypeError('"highWaterMark" must be a number');
+    }
 
-  // cast to ints.
-  this.highWaterMark = Math.floor(this.highWaterMark);
+    if (hwm < 0) {
+      throw new RangeError('"highWaterMark" must not be negative');
+    }
+
+    // cast to ints.
+    this.highWaterMark = Math.floor(hwm);
+  }
 
   // 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

@@ -51,11 +51,21 @@ function WritableState(options, stream) {
   // Note: 0 is a valid value, means that we always return false if
   // the entire buffer is not flushed immediately on write()
   var hwm = options.highWaterMark;
-  var defaultHwm = this.objectMode ? 16 : 16 * 1024;
-  this.highWaterMark = (hwm || hwm === 0) ? hwm : defaultHwm;
+  if (hwm == null) {
+    var defaultHwm = this.objectMode ? 16 : 16 * 1024;
+    this.highWaterMark = defaultHwm;
+  } else {
+    if (typeof hwm !== 'number') {
+      throw new TypeError('"highWaterMark" must be a number');
+    }
 
-  // cast to ints.
-  this.highWaterMark = Math.floor(this.highWaterMark);
+    if (hwm < 0) {
+      throw new RangeError('"highWaterMark" must not be negative');
+    }
+
+    // cast to ints.
+    this.highWaterMark = Math.floor(hwm);
+  }
 
   // drain event flag.
   this.needDrain = false;