fs: read whole file only in regular files

lib/fs.js

@@ -317,7 +317,7 @@ function readFileAfterStat(err, st) {
   if (err)
     return context.close(err);
 
-  var size = context.size = st.size;
+  var size = context.size = st.isFile() ? st.size : 0;
 
   if (size === 0) {
     context.buffers = [];
@@ -395,10 +395,12 @@ fs.readFileSync = function(path, options) {
   var flag = options.flag || 'r';
   var fd = fs.openSync(path, flag, 0o666);
 
+  var st;
   var size;
   var threw = true;
   try {
-    size = fs.fstatSync(fd).size;
+    st = fs.fstatSync(fd);
+    size = st.isFile() ? st.size : 0;
     threw = false;
   } finally {
     if (threw) fs.closeSync(fd);

test/parallel/test-fs-readfile-pipe-large.js

@@ -0,0 +1,41 @@
+var common = require('../common');
+var assert = require('assert');
+var path = require('path');
+
+// 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 filename = path.join(common.tmpDir, '/readfile_pipe_large_test.txt');
+var dataExpected = new Array(1000000).join('a');
+fs.writeFileSync(filename, dataExpected);
+
+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 ' + filename + ' | ' + node + ' ' + f + ' child';
+exec(cmd, { maxBuffer: 1000000 }, 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');
+});
+
+process.on('exit', function() {
+  fs.unlinkSync(filename);
+});

test/parallel/test-fs-readfile-zero-byte-liar.js

@@ -17,7 +17,7 @@ fs.fstat = function(fd, cb) {
 };
 
 fs.fstatSync = function(fd) {
-  var st = fs._fstatSync;
+  var st = fs._fstatSync(fd);
   st.size = 0;
   return st;
 };

test/parallel/test-fs-readfilesync-pipe-large.js

@@ -0,0 +1,38 @@
+var common = require('../common');
+var assert = require('assert');
+var path = require('path');
+
+// 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 filename = path.join(common.tmpDir, '/readfilesync_pipe_large_test.txt');
+var dataExpected = new Array(1000000).join('a');
+fs.writeFileSync(filename, dataExpected);
+
+if (process.argv[2] === 'child') {
+  process.stdout.write(fs.readFileSync('/dev/stdin', 'utf8'));
+  return;
+}
+
+var exec = require('child_process').exec;
+var f = JSON.stringify(__filename);
+var node = JSON.stringify(process.execPath);
+var cmd = 'cat ' + filename + ' | ' + node + ' ' + f + ' child';
+exec(cmd, { maxBuffer: 1000000 }, 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');
+});
+
+process.on('exit', function() {
+  fs.unlinkSync(filename);
+});