fix: revert "fs: stop lazy loading stream constructors"

Fixes electron/electron#15543
by reverting 484140e.

This commit was added to retain backwards compatibility in the 10.x
branch and shouldn't be an issue in Node 11 / Electron based on 11.x.

More info can be found at nodejs/node#21489

lib/fs.js

@@ -52,7 +52,6 @@ const {
 } = errors.codes;
 
 const { FSReqWrap, statValues } = binding;
-const { ReadStream, WriteStream } = require('internal/fs/streams');
 const internalFS = require('internal/fs/utils');
 const { getPathFromURL } = require('internal/url');
 const internalUtil = require('internal/util');
@@ -94,6 +93,13 @@ let fs;
 let promises;
 let watchers;
 let ReadFileContext;
+let ReadStream;
+let WriteStream;
+
+// These have to be separate because of how graceful-fs happens to do it's
+// monkeypatching.
+let FileReadStream;
+let FileWriteStream;
 
 const isWindows = process.platform === 'win32';
 
@@ -1702,11 +1708,20 @@ function copyFileSync(src, dest, flags) {
   handleErrorFromBinding(ctx);
 }
 
+function lazyLoadStreams() {
+  if (!ReadStream) {
+    ({ ReadStream, WriteStream } = require('internal/fs/streams'));
+    [ FileReadStream, FileWriteStream ] = [ ReadStream, WriteStream ];
+  }
+}
+
 function createReadStream(path, options) {
+  lazyLoadStreams();
   return new ReadStream(path, options);
 }
 
 function createWriteStream(path, options) {
+  lazyLoadStreams();
   return new WriteStream(path, options);
 }
 
@@ -1790,12 +1805,43 @@ module.exports = fs = {
   Dirent,
   Stats,
 
-  // Stream constructors
-  ReadStream,
-  WriteStream,
-  // Legacy names...
-  FileReadStream: ReadStream,
-  FileWriteStream: WriteStream,
+  get ReadStream() {
+    lazyLoadStreams();
+    return ReadStream;
+  },
+
+  set ReadStream(val) {
+    ReadStream = val;
+  },
+
+  get WriteStream() {
+    lazyLoadStreams();
+    return WriteStream;
+  },
+
+  set WriteStream(val) {
+    WriteStream = val;
+  },
+
+  // Legacy names... these have to be separate because of how graceful-fs
+  // (and possibly other) modules monkey patch the values.
+  get FileReadStream() {
+    lazyLoadStreams();
+    return FileReadStream;
+  },
+
+  set FileReadStream(val) {
+    FileReadStream = val;
+  },
+
+  get FileWriteStream() {
+    lazyLoadStreams();
+    return FileWriteStream;
+  },
+
+  set FileWriteStream(val) {
+    FileWriteStream = val;
+  },
 
   // For tests
   _toUnixTimestamp: toUnixTimestamp

lib/internal/fs/streams.js

@@ -8,6 +8,7 @@ const {
   ERR_INVALID_ARG_TYPE,
   ERR_OUT_OF_RANGE
 } = require('internal/errors').codes;
+const fs = require('fs');
 const { Buffer } = require('buffer');
 const {
   copyObject,
@@ -17,13 +18,6 @@ const { Readable, Writable } = require('stream');
 const { getPathFromURL } = require('internal/url');
 const util = require('util');
 
-let fs;
-function lazyFs() {
-  if (fs === undefined)
-    fs = require('fs');
-  return fs;
-}
-
 const kMinPoolSpace = 128;
 
 let pool;
@@ -107,7 +101,7 @@ function ReadStream(path, options) {
 util.inherits(ReadStream, Readable);
 
 ReadStream.prototype.open = function() {
-  lazyFs().open(this.path, this.flags, this.mode, (er, fd) => {
+  fs.open(this.path, this.flags, this.mode, (er, fd) => {
     if (er) {
       if (this.autoClose) {
         this.destroy();
@@ -157,7 +151,7 @@ ReadStream.prototype._read = function(n) {
     return this.push(null);
 
   // the actual read.
-  lazyFs().read(this.fd, pool, pool.used, toRead, this.pos, (er, bytesRead) => {
+  fs.read(this.fd, pool, pool.used, toRead, this.pos, (er, bytesRead) => {
     if (er) {
       if (this.autoClose) {
         this.destroy();
@@ -200,7 +194,7 @@ ReadStream.prototype._destroy = function(err, cb) {
 };
 
 function closeFsStream(stream, cb, err) {
-  lazyFs().close(stream.fd, (er) => {
+  fs.close(stream.fd, (er) => {
     er = er || err;
     cb(er);
     stream.closed = true;
@@ -265,7 +259,7 @@ WriteStream.prototype._final = function(callback) {
 };
 
 WriteStream.prototype.open = function() {
-  lazyFs().open(this.path, this.flags, this.mode, (er, fd) => {
+  fs.open(this.path, this.flags, this.mode, (er, fd) => {
     if (er) {
       if (this.autoClose) {
         this.destroy();
@@ -293,7 +287,7 @@ WriteStream.prototype._write = function(data, encoding, cb) {
     });
   }
 
-  lazyFs().write(this.fd, data, 0, data.length, this.pos, (er, bytes) => {
+  fs.write(this.fd, data, 0, data.length, this.pos, (er, bytes) => {
     if (er) {
       if (this.autoClose) {
         this.destroy();