stream: validate readable defaultEncoding

PR-URL: #46430
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Robert Nagy <ronagy@icloud.com>

Author: marco-ippolito

lib/internal/streams/readable.js

@@ -65,6 +65,7 @@ const {
 ERR_OUT_OF_RANGE,
 ERR_STREAM_PUSH_AFTER_EOF,
 ERR_STREAM_UNSHIFT_AFTER_END_EVENT,
+ERR_UNKNOWN_ENCODING
 }
 }=require('internal/errors');
 const{ validateObject }=require('internal/validators');
@@ -162,7 +163,14 @@ function ReadableState(options, stream, isDuplex) {
 // Crypto is kind of old and crusty. Historically, its default string
 // encoding is 'binary' so we have to make this configurable.
 // Everything else in the universe uses 'utf8', though.
-this.defaultEncoding=(options&&options.defaultEncoding)||'utf8';
+constdefaultEncoding=options?.defaultEncoding;
+if(defaultEncoding==null){
+this.defaultEncoding='utf8';
+}elseif(Buffer.isEncoding(defaultEncoding)){
+this.defaultEncoding=defaultEncoding;
+}else{
+thrownewERR_UNKNOWN_ENCODING(defaultEncoding);
+}
 
 // Ref the piped dest which we need a drain event on it
 // type: null | Writable | Set<Writable>.

test/parallel/test-stream-readable-default-encoding.js

@@ -0,0 +1,37 @@
+'use strict';
+constcommon=require('../common');
+constassert=require('assert');
+const{ Readable }=require('stream');
+
+{
+assert.throws(()=>{
+newReadable({
+read: ()=>{},
+defaultEncoding: 'my invalid encoding',
+});
+},{
+code: 'ERR_UNKNOWN_ENCODING',
+});
+}
+
+{
+constr=newReadable({
+read(){},
+defaultEncoding: 'hex'
+});
+
+r.push('ab');
+
+r.on('data',common.mustCall((chunk)=>assert.strictEqual(chunk.toString('hex'),'ab')),1);
+}
+
+{
+constr=newReadable({
+read(){},
+defaultEncoding: 'hex',
+});
+
+r.push('xy','utf-8');
+
+r.on('data',common.mustCall((chunk)=>assert.strictEqual(chunk.toString('utf-8'),'xy')),1);
+}