buffer: validate list elements in Buffer.concat

Without this change, if any of the elements in the list to be concatenated is not a Buffer instance, the method fails with "buf.copy is not a function". Make an isBuffer check before using the copy method so that we can throw with a better message. Fixes: #4949 PR-URL: #4951 Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Sakthipriyan Vairamani <[email protected]> Reviewed-By: Roman Klauke <[email protected]>

Author: targos

lib/buffer.js

@@ -219,7 +219,7 @@ Buffer.isEncoding = function(encoding){
 
 Buffer.concat=function(list,length){
 if(!Array.isArray(list))
-thrownewTypeError('list argument must be an Array of Buffers.');
+thrownewTypeError('list argument must be an Array of Buffers');
 
 if(list.length===0)
 returnnewBuffer(0);
@@ -236,6 +236,8 @@ Buffer.concat = function(list, length){
 varpos=0;
 for(leti=0;i<list.length;i++){
 varbuf=list[i];
+if(!Buffer.isBuffer(buf))
+thrownewTypeError('list argument must be an Array of Buffers');
 buf.copy(buffer,pos);
 pos+=buf.length;
 }

test/parallel/test-buffer-concat.js

@@ -20,8 +20,18 @@ assert(flatOne !== one[0]);
 assert(flatLong.toString()===(newArray(10+1).join('asdf')));
 assert(flatLongLen.toString()===(newArray(10+1).join('asdf')));
 
-assert.throws(function(){
-Buffer.concat([42]);
-},TypeError);
+assertWrongList();
+assertWrongList(null);
+assertWrongList(newBuffer('hello'));
+assertWrongList([42]);
+assertWrongList(['hello','world']);
+assertWrongList(['hello',newBuffer('world')]);
 
-console.log('ok');
+functionassertWrongList(value){
+assert.throws(function(){
+Buffer.concat(value);
+},function(err){
+returnerrinstanceofTypeError&&
+err.message==='list argument must be an Array of Buffers';
+});
+}