From cb06abe1e586217e31907d792ef3b967936e3f77 Mon Sep 17 00:00:00 2001
From: Ryan Dahl <ry@tinyclouds.org>
Date: Thu, 27 Jan 2011 17:45:17 -0800
Subject: [PATCH] Helpful error when child_process.exec hit maxBuffer

---
 lib/child_process.js                |  8 +++++++-
 test/simple/test-exec-max-buffer.js | 10 ++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 test/simple/test-exec-max-buffer.js

diff --git a/lib/child_process.js b/lib/child_process.js
index 71792f7a2b..fd4a314139 100644
--- a/lib/child_process.js
+++ b/lib/child_process.js
@@ -60,6 +60,8 @@ exports.execFile = function(file /* args, options, callback */) {
   var exited = false;
   var timeoutId;
 
+  var err;
+
   function exithandler(code, signal) {
     if (exited) return;
     exited = true;
@@ -71,7 +73,9 @@ exports.execFile = function(file /* args, options, callback */) {
 
     if (!callback) return;
 
-    if (code === 0 && signal === null) {
+    if (err) {
+      callback(err, stdout, stderr);
+    } else if (code === 0 && signal === null) {
       callback(null, stdout, stderr);
     } else {
       var e = new Error('Command failed: ' + stderr);
@@ -103,6 +107,7 @@ exports.execFile = function(file /* args, options, callback */) {
   child.stdout.addListener('data', function(chunk) {
     stdout += chunk;
     if (stdout.length > options.maxBuffer) {
+      err = new Error('maxBuffer exceeded.');
       kill();
     }
   });
@@ -110,6 +115,7 @@ exports.execFile = function(file /* args, options, callback */) {
   child.stderr.addListener('data', function(chunk) {
     stderr += chunk;
     if (stderr.length > options.maxBuffer) {
+      err = new Error('maxBuffer exceeded.');
       kill();
     }
   });
diff --git a/test/simple/test-exec-max-buffer.js b/test/simple/test-exec-max-buffer.js
new file mode 100644
index 0000000000..a5a24eabea
--- /dev/null
+++ b/test/simple/test-exec-max-buffer.js
@@ -0,0 +1,10 @@
+var common = require('../common');
+var exec = require('child_process').exec;
+var assert = require('assert');
+
+var cmd = 'echo "hello world"';
+
+exec(cmd, { maxBuffer: 5 }, function(err, stdout, stderr) {
+  assert.ok(err);
+  assert.ok(/maxBuffer/.test(err.message));
+});