nodejs · Trott · Jun 22, 2016 · Jun 23, 2016 · Jun 26, 2016 · Jun 27, 2016
diff --git a/lib/child_process.js b/lib/child_process.js
@@ -146,13 +146,15 @@ exports.execFile = function(file /*, args, options, callback*/) {
   });
 
   var encoding;
-  var stdoutState;
-  var stderrState;
-  var _stdout = [];
-  var _stderr = [];
+  var _stdout;
+  var _stderr;
   if (options.encoding !== 'buffer' && Buffer.isEncoding(options.encoding)) {
     encoding = options.encoding;
+    _stdout = '';
+    _stderr = '';
   } else {
+    _stdout = [];
+    _stderr = [];
     encoding = null;
   }
   var stdoutLen = 0;
@@ -174,23 +176,16 @@ exports.execFile = function(file /*, args, options, callback*/) {
 
     if (!callback) return;
 
-    var stdout = Buffer.concat(_stdout, stdoutLen);
-    var stderr = Buffer.concat(_stderr, stderrLen);
-
-    var stdoutEncoding = encoding;
-    var stderrEncoding = encoding;
-
-    if (stdoutState && stdoutState.decoder)
-      stdoutEncoding = stdoutState.decoder.encoding;
-
-    if (stderrState && stderrState.decoder)
-      stderrEncoding = stderrState.decoder.encoding;
-
-    if (stdoutEncoding)
-      stdout = stdout.toString(stdoutEncoding);
-
-    if (stderrEncoding)
-      stderr = stderr.toString(stderrEncoding);
+    // merge chunks
+    var stdout;
+    var stderr;
+    if (encoding) {
+      stdout = _stdout;
+      stderr = _stderr;
+    } else {
+      stdout = Buffer.concat(_stdout);
+      stderr = Buffer.concat(_stderr);
+    }
 
     if (ex) {
       // Will be handled later
@@ -250,45 +245,39 @@ exports.execFile = function(file /*, args, options, callback*/) {
   }
 
   if (child.stdout) {
-    stdoutState = child.stdout._readableState;
+    if (encoding)
+      child.stdout.setEncoding(encoding);
 
     child.stdout.addListener('data', function(chunk) {
-      // If `child.stdout.setEncoding()` happened in userland, convert string to
-      // Buffer.
-      if (stdoutState.decoder) {
-        chunk = Buffer.from(chunk, stdoutState.decoder.encoding);
-      }
-
-      stdoutLen += chunk.byteLength;
+      stdoutLen += encoding ? Buffer.byteLength(chunk, encoding) : chunk.length;
 
       if (stdoutLen > options.maxBuffer) {
         ex = new Error('stdout maxBuffer exceeded');
-        stdoutLen -= chunk.byteLength;
         kill();
       } else {
-        _stdout.push(chunk);
+        if (encoding)
+          _stdout += chunk;
+        else
+          _stdout.push(chunk);
       }
     });
   }
 
   if (child.stderr) {
-    stderrState = child.stderr._readableState;
+    if (encoding)
+      child.stderr.setEncoding(encoding);
 
     child.stderr.addListener('data', function(chunk) {
-      // If `child.stderr.setEncoding()` happened in userland, convert string to
-      // Buffer.
-      if (stderrState.decoder) {
-        chunk = Buffer.from(chunk, stderrState.decoder.encoding);
-      }
-
-      stderrLen += chunk.byteLength;
+      stderrLen += encoding ? Buffer.byteLength(chunk, encoding) : chunk.length;
 
       if (stderrLen > options.maxBuffer) {
         ex = new Error('stderr maxBuffer exceeded');
-        stderrLen -= chunk.byteLength;
         kill();
       } else {
-        _stderr.push(chunk);
+        if (encoding)
+          _stderr += chunk;
+        else
+          _stderr.push(chunk);
       }
     });
   }

diff --git a/test/parallel/test-child-process-exec-maxBuffer.js b/test/parallel/test-child-process-exec-maxBuffer.js
@@ -0,0 +1,31 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const cp = require('child_process');
+
+function checkFactory(streamName) {
+  return common.mustCall((err) => {
+    const message = `${streamName} maxBuffer exceeded`;
+    assert.strictEqual(err.message, message);
+  });
+}
+
+{
+  const cmd = 'echo "hello world"';
+
+  cp.exec(cmd, { maxBuffer: 5 }, checkFactory('stdout'));
+}
+
+const unicode = '中文测试'; // length = 4, byte length = 12
+
+{
+  const cmd = `"${process.execPath}" -e "console.log('${unicode}');"`;
+
+  cp.exec(cmd, {maxBuffer: 10}, checkFactory('stdout'));
+}
+
+{
+  const cmd = `"${process.execPath}" -e "console.('${unicode}');"`;
+
+  cp.exec(cmd, {maxBuffer: 10}, checkFactory('stderr'));
+}
diff --git a/...-child-process-exec-stdout-data-string.js → ...process-exec-stdout-stderr-data-string.js b/...-child-process-exec-stdout-data-string.js → ...process-exec-stdout-stderr-data-string.js
@@ -4,13 +4,20 @@ const common = require('../common');
 const assert = require('assert');
 const exec = require('child_process').exec;
 
-const expectedCalls = 2;
-
-const cb = common.mustCall((data) => {
-  assert.strictEqual(typeof data, 'string');
-}, expectedCalls);
+var stdoutCalls = 0;
+var stderrCalls = 0;
 
 const command = common.isWindows ? 'dir' : 'ls';
-exec(command).stdout.on('data', cb);
+exec(command).stdout.on('data', (data) => {
+  stdoutCalls += 1;
+});
+
+exec('fhqwhgads').stderr.on('data', (data) => {
+  assert.strictEqual(typeof data, 'string');
+  stderrCalls += 1;
+});
 
-exec('fhqwhgads').stderr.on('data', cb);
+process.on('exit', () => {
+  assert(stdoutCalls > 0);
+  assert(stderrCalls > 0);
+});
diff --git a/test/parallel/test-child-process-maxBuffer-stderr.js b/test/parallel/test-child-process-maxBuffer-stderr.js
diff --git a/test/parallel/test-child-process-maxBuffer-stdout.js b/test/parallel/test-child-process-maxBuffer-stdout.js
diff --git a/test/parallel/test-exec-max-buffer.js b/test/parallel/test-exec-max-buffer.js