repl: make sure historyPath is trimmed

If one were to set NODE_REPL_HISTORY to a string that contains only a
space (" "), then the history file would be created with that name
which can cause problems are certain systems.

PR-URL: #4539
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

doc/api/repl.markdown

@@ -37,7 +37,7 @@ via the following environment variables:
  - `NODE_REPL_HISTORY` - When a valid path is given, persistent REPL history
  will be saved to the specified file rather than `.node_repl_history` in the
  user's home directory. Setting this value to `""` will disable persistent
- REPL history.
+ REPL history. Whitespace will be trimmed from the value.
  - `NODE_REPL_HISTORY_SIZE` - defaults to `1000`. Controls how many lines of
  history will be persisted if history is available. Must be a positive number.
  - `NODE_REPL_MODE` - may be any of `sloppy`, `strict`, or `magic`. Defaults

lib/internal/repl.js

@@ -55,15 +55,26 @@ function createRepl(env, opts, cb) {
  }
 
  const repl = REPL.start(opts);
- if (opts.terminal && env.NODE_REPL_HISTORY !== '') {
+ if (opts.terminal) {
  return setupHistory(repl, env.NODE_REPL_HISTORY,
  env.NODE_REPL_HISTORY_FILE, cb);
  }
+
  repl._historyPrev = _replHistoryMessage;
  cb(null, repl);
 }
 
 function setupHistory(repl, historyPath, oldHistoryPath, ready) {
+ // Empty string disables persistent history.
+
+ if (typeof historyPath === 'string')
+ historyPath = historyPath.trim();
+
+ if (historyPath === '') {
+ repl._historyPrev = _replHistoryMessage;
+ return ready(null, repl);
+ }
+
  if (!historyPath) {
  try {
  historyPath = path.join(os.homedir(), '.node_repl_history');

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

@@ -85,6 +85,11 @@ const tests = [
  test: [UP],
  expected: [prompt, replDisabled, prompt]
  },
+ {
+ env: { NODE_REPL_HISTORY: ' ' },
+ test: [UP],
+ expected: [prompt, replDisabled, prompt]
+ },
  {
  env: { NODE_REPL_HISTORY: '',
  NODE_REPL_HISTORY_FILE: enoentHistoryPath },