fs: avoid circular dependency in SyncWriteStream

Previously, there was a circular dependency on the public fs module in
SyncWriteStream. Moving the implementations of fs.writeSync and
fs.closeSync to internal/fs allows us to avoid that circular dependency.

Fixes: nodejs#11257

lib/fs.js

@@ -42,6 +42,8 @@ const internalURL = require('internal/url');
 const internalUtil = require('internal/util');
 const assertEncoding = internalFS.assertEncoding;
 const stringToFlags = internalFS.stringToFlags;
+const writeSync = internalFS.writeSync;
+const closeSync = internalFS.closeSync;
 const getPathFromURL = internalURL.getPathFromURL;
 const { StorageObject } = require('internal/querystring');
 
@@ -600,9 +602,7 @@ fs.close = function(fd, callback) {
   binding.close(fd, req);
 };
 
-fs.closeSync = function(fd) {
-  return binding.close(fd);
-};
+fs.closeSync = closeSync;
 
 function modeNum(m, def) {
   if (typeof m === 'number')
@@ -710,22 +710,7 @@ fs.write = function(fd, buffer, offset, length, position, callback) {
 //  fs.writeSync(fd, buffer[, offset[, length[, position]]]);
 // OR
 //  fs.writeSync(fd, string[, position[, encoding]]);
-fs.writeSync = function(fd, buffer, offset, length, position) {
-  if (isUint8Array(buffer)) {
-    if (position === undefined)
-      position = null;
-    if (typeof offset !== 'number')
-      offset = 0;
-    if (typeof length !== 'number')
-      length = buffer.length - offset;
-    return binding.writeBuffer(fd, buffer, offset, length, position);
-  }
-  if (typeof buffer !== 'string')
-    buffer += '';
-  if (offset === undefined)
-    offset = null;
-  return binding.writeString(fd, buffer, offset, length, position);
-};
+fs.writeSync = writeSync;
 
 fs.rename = function(oldPath, newPath, callback) {
   callback = makeCallback(callback);

lib/internal/fs.js

@@ -2,9 +2,10 @@
 
 const Buffer = require('buffer').Buffer;
 const Writable = require('stream').Writable;
-const fs = require('fs');
 const util = require('util');
 const constants = process.binding('constants').fs;
+const binding = process.binding('fs');
+const { isUint8Array } = process.binding('util');
 
 const O_APPEND = constants.O_APPEND | 0;
 const O_CREAT = constants.O_CREAT | 0;
@@ -54,6 +55,27 @@ function stringToFlags(flag) {
   throw new Error('Unknown file open flag: ' + flag);
 }
 
+function writeSync(fd, buffer, offset, length, position) {
+  if (isUint8Array(buffer)) {
+    if (position === undefined)
+      position = null;
+    if (typeof offset !== 'number')
+      offset = 0;
+    if (typeof length !== 'number')
+      length = buffer.length - offset;
+    return binding.writeBuffer(fd, buffer, offset, length, position);
+  }
+  if (typeof buffer !== 'string')
+    buffer += '';
+  if (offset === undefined)
+    offset = null;
+  return binding.writeString(fd, buffer, offset, length, position);
+}
+
+function closeSync(fd) {
+  return binding.close(fd);
+}
+
 // Temporary hack for process.stdout and process.stderr when piped to files.
 function SyncWriteStream(fd, options) {
   Writable.call(this);
@@ -70,7 +92,7 @@ function SyncWriteStream(fd, options) {
 util.inherits(SyncWriteStream, Writable);
 
 SyncWriteStream.prototype._write = function(chunk, encoding, cb) {
-  fs.writeSync(this.fd, chunk, 0, chunk.length);
+  writeSync(this.fd, chunk, 0, chunk.length);
   cb();
   return true;
 };
@@ -80,7 +102,7 @@ SyncWriteStream.prototype._destroy = function() {
     return;
 
   if (this.autoClose)
-    fs.closeSync(this.fd);
+    closeSync(this.fd);
 
   this.fd = null;
   return true;
@@ -97,5 +119,7 @@ module.exports = {
   assertEncoding,
   stringToFlags,
   SyncWriteStream,
-  realpathCacheKey: Symbol('realpathCacheKey')
+  realpathCacheKey: Symbol('realpathCacheKey'),
+  writeSync,
+  closeSync
 };

test/parallel/test-stdin-require.js

@@ -0,0 +1,27 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const execSync = require('child_process').execSync;
+const fs = require('fs');
+const path = require('path');
+
+// Prevents a regression where redirecting stderr and receiving input script
+// via stdin works properly.
+
+common.refreshTmpDir();
+const filename = path.join(common.fixturesDir, 'baz.js');
+const out = path.join(common.tmpDir, 'js.out');
+const bin = process.execPath;
+const input = `require('${filename}'); console.log('PASS');`;
+const cmd = common.isWindows ?
+  `echo "${input}" | ${bin} > ${out} 2>&1` :
+  `echo "${input}" | ${bin} &> ${out}`;
+
+// This will throw if internal/fs has a circular dependency.
+assert.strictEqual(execSync(cmd).toString(), '');
+
+const result = fs.readFileSync(out, 'utf8').trim();
+assert.strictEqual(result, 'PASS');
+
+fs.unlinkSync(out);