lib: fix stdio/ipc sync i/o regression

process.send() should be synchronous, it should block until the message
has been sent in full, but it wasn't after the second-to-last libuv
upgrade because of commit libuv/libuv@393c1c5 ("unix: set non-block
mode in uv_{pipe,tcp,udp}_open"), which made its way into io.js in
commit 07bd05b ("deps: update libuv to 1.2.1").

Commit libuv/libuv@b36d4ff ("unix: implement uv_stream_set_blocking()")
as landed in io.js in commit 9681fca ("deps: update libuv to 1.4.0")
makes it possible to restore the synchronous behavior again and that's
precisely what this commit does.

The same line of reasoning applies to `net.Socket({ fd: 1 })`: creating
a socket object from a stdio file descriptor, like the `process.stdout`
getter does, should put the file descriptor in blocking mode for
compatibility reasons.

PR-URL: nodejs/node#774
Reviewed-by: Trevor Norris <trev.norris@gmail.com>

lib/child_process.js

@@ -586,6 +586,13 @@ exports._forkChild = function(fd) {
   // set process.send()
   var p = createPipe(true);
   p.open(fd);
+
+  // p.open() puts the file descriptor in non-blocking mode
+  // but it must be synchronous for backwards compatibility.
+  var err = p.setBlocking(true);
+  if (err)
+    throw errnoException(err, 'setBlocking');
+
   p.unref();
   setupChannel(process, p);
 

lib/net.js

@@ -155,9 +155,9 @@ function Socket(options) {
   } else if (!util.isUndefined(options.fd)) {
     this._handle = createHandle(options.fd);
     this._handle.open(options.fd);
-    if ((options.fd == 1 || options.fd == 2) &&
-        (this._handle instanceof Pipe) &&
-        process.platform === 'win32') {
+    // this._handle.open() puts the file descriptor in non-blocking
+    // mode but it must be synchronous for backwards compatibility.
+    if ((options.fd == 1 || options.fd == 2) && this._handle instanceof Pipe) {
       // Make stdout and stderr blocking on Windows
       var err = this._handle.setBlocking(true);
       if (err)

test/simple/test-child-process-sync-process-send.js

@@ -0,0 +1,44 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+var fork = require('child_process').fork;
+var N = 4 << 20;  // 4 MB
+
+for (var big = '*'; big.length < N; big += big);
+
+if (process.argv[2] === 'child') {
+  process.send(big);
+  process.exit(42);
+}
+
+var proc = fork(__filename, ['child']);
+
+proc.on('message', common.mustCall(function(msg) {
+  assert.equal(typeof msg, 'string');
+  assert.equal(msg.length, N);
+  assert.equal(msg, big);
+}));
+
+proc.on('exit', common.mustCall(function(exitCode) {
+  assert.equal(exitCode, 42);
+}));

test/simple/test-net-sync-stdio.js

@@ -0,0 +1,44 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+var spawn = require('child_process').spawn;
+var N = 4 << 20;  // 4 MB
+
+for (var big = '*'; big.length < N; big += big);
+
+if (process.argv[2] === 'child') {
+  process.stdout.write(big);
+  process.exit(42);
+}
+
+var stdio = ['inherit', 'pipe', 'inherit'];
+var proc = spawn(process.execPath, [__filename, 'child'], { stdio: stdio });
+
+var chunks = [];
+proc.stdout.setEncoding('utf8');
+proc.stdout.on('data', chunks.push.bind(chunks));
+
+proc.on('exit', common.mustCall(function(exitCode) {
+  assert.equal(exitCode, 42);
+  assert.equal(chunks.join(''), big);
+}));