repl: create history file with mode 0600

Set the mode bits on the history file to 0o600 instead of leaving it
unspecified, which resulted in 0o755 on Unices.
Test code mostly written by Trott:
#3392 (comment).
PR-URL: #3394Fixes: #3392
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: XeCycle

lib/internal/repl.js

@@ -93,7 +93,10 @@ function setupHistory(repl, historyPath, oldHistoryPath, ready) {
 varwriting=false;
 varpending=false;
 repl.pause();
-fs.open(historyPath,'a+',oninit);
+// History files are conventionally not readable by others:
+// https://github.com/nodejs/node/issues/3392
+// https://github.com/nodejs/node/pull/3394
+fs.open(historyPath,'a+',0o0600,oninit);
 
 functiononinit(err,hnd){
 if(err){

test/parallel/test-repl-history-perm.js

@@ -0,0 +1,53 @@
+'use strict';
+// Flags: --expose_internals
+
+constcommon=require('../common');
+
+if(common.isWindows){
+console.log('1..0 # Skipped: Win32 uses ACLs for file permissions, '+
+'modes are always 0666 and says nothing about group/other '+
+'read access.');
+return;
+}
+
+constassert=require('assert');
+constpath=require('path');
+constfs=require('fs');
+constrepl=require('internal/repl');
+constDuplex=require('stream').Duplex;
+// Invoking the REPL should create a repl history file at the specified path
+// and mode 600.
+
+varstream=newDuplex();
+stream.pause=stream.resume=function(){};
+// ends immediately
+stream._read=function(){
+this.push(null);
+};
+stream._write=function(c,e,cb){
+cb();
+};
+stream.readable=stream.writable=true;
+
+common.refreshTmpDir();
+constreplHistoryPath=path.join(common.tmpDir,'.node_repl_history');
+
+constcheckResults=common.mustCall(function(err,r){
+if(err)
+throwerr;
+r.input.end();
+conststat=fs.statSync(replHistoryPath);
+assert.strictEqual(
+stat.mode&0o777,0o600,
+'REPL history file should be mode 0600');
+});
+
+repl.createInternalRepl(
+{NODE_REPL_HISTORY: replHistoryPath},
+{
+terminal: true,
+input: stream,
+output: stream
+},
+checkResults
+);