Fix fs.readfile('/dev/stdin')

There is no need for fs.readFile() to be using pread rather than read.
The default semantics of read() are such that subsequent reads are where
we want them anyway.

lib/fs.js

@@ -135,9 +135,9 @@ fs.readFile = function(path, encoding_) {
   function read() {
     if (size === 0) {
       buffer = new Buffer(8192);
-      fs.read(fd, buffer, 0, 8192, pos, afterRead);
+      fs.read(fd, buffer, 0, 8192, -1, afterRead);
     } else {
-      fs.read(fd, buffer, pos, size - pos, pos, afterRead);
+      fs.read(fd, buffer, pos, size - pos, -1, afterRead);
     }
   }
 

test/simple/test-fs-readfile-pipe.js

@@ -0,0 +1,55 @@
+// 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');
+
+// simulate `cat readfile.js | node readfile.js`
+
+// TODO: Have some way to make this work on windows.
+if (process.platform === 'win32') {
+  console.error('No /dev/stdin on windows.  Skipping test.');
+  process.exit();
+}
+
+var fs = require('fs');
+
+var dataExpected = fs.readFileSync(__filename, 'utf8');
+
+if (process.argv[2] === 'child') {
+  fs.readFile('/dev/stdin', function(er, data) {
+    if (er) throw er;
+    process.stdout.write(data);
+  });
+  return;
+}
+
+var exec = require('child_process').exec;
+var f = JSON.stringify(__filename);
+var node = JSON.stringify(process.execPath);
+var cmd = 'cat ' + f + ' | ' + node + ' ' + f + ' child';
+exec(cmd, function(err, stdout, stderr) {
+  if (err) console.error(err);
+  assert(!err, 'it exits normally');
+  assert(stdout === dataExpected, 'it reads the file and outputs it');
+  assert(stderr === '', 'it does not write to stderr');
+  console.log('ok');
+});