var fs = require('fs')// ...工具方法

module.exports = patch(require('./fs.js'))
if (process.env.TEST_GRACEFUL_FS_GLOBAL_PATCH) {module.exports = patch(fs)
}module.exports.close = fs.close = (function(fs$close) { /*...*/ })(fs.close)module.exports.closeSync = fs.closeSync = (function(fs$closeSync) { /*...*/ })(fs.closeSync)function patch(fs) {// fs方法二次封装return fs
}

var util = require('util');// 检测此方法是否存在并返回一个debug方法
if (util.debuglog)debug = util.debuglog('gfs4');
// 测试进程参数NODE_DEBUG是否包含'gfs4'
else if (/\bgfs4\b/i.test(process.env.NODE_DEBUG || '')) {//  自定义一个debug函数debug = (...args) => {var m = util.format.apply(util, args);m = 'GFS4: ' + m.split(/\n/).join('\nGFS4: ');console.error(m);}
}if (/\bgfs4\b/i.test(process.env.NODE_DEBUG || '')) {// 监听退出事件process.on('exit', function() {// 批量输出日志内容
        debug(queue);// 使用==测试参数是否相等 不等抛出errorrequire('assert').equal(queue.length, 0);})
}

const util = require('util');
debug = (...args) => {var m = util.format.apply(util, args);m = 'GFS4: ' + m.split(/\n/).join('\nGFS4: ');console.error(m);
}
debug(`log1
log2
log3`);

var debugs = {};
// 收集所有DEBUG的环境名
var debugEnviron;function debuglog(set) {if (debugEnviron === undefined) {// 从NODE_DEBUG环境变量中收集所有的日志输出参数// 这里全部转为大写// 这就说明为什么debuglog传的是gfs4 输出的是GFS4debugEnviron = new Set((process.env.NODE_DEBUG || '').split(',').map((s) => s.toUpperCase()));}set = set.toUpperCase();// 没有该debuglog函数就创建一个if (!debugs[set]) {// 只对指定的参数进行输出if (debugEnviron.has(set)) {var pid = process.pid;debugs[set] = function() {// 格式化参数信息var msg = exports.format.apply(exports, arguments);// 依次输出：参数名 进程号 信息console.error('%s %d: %s', set, pid, msg);};} else {debugs[set] = function() {};}}return debugs[set];
}

'use strict'var fs = require('fs')module.exports = clone(fs)// 拷贝对象
function clone(obj) {if (obj === null || typeof obj !== 'object')return objif (obj instanceof Object)var copy = { __proto__: obj.__proto__ }elsevar copy = Object.create(null)Object.getOwnPropertyNames(obj).forEach(function(key) {Object.defineProperty(copy, key, Object.getOwnPropertyDescriptor(obj, key))})return copy
}

const a = {'string': 1,'arr': [1],
}
const b = clone(a);
b.arr[0] = 2;
b.string = 2;
console.log(a); // {string:1,arr:[2]}
const c = a;
c.arr[0] = 3;
c.string = 3;
console.log(a); // {string:3,arr:[3]}

function patch(fs) {// Everything that references the open() function needs to be in here// 跨平台兼容处理
    polyfills(fs)fs.gracefulify = patch;// 遗留名字fs.FileReadStream = ReadStream; // Legacy name.fs.FileWriteStream = WriteStream; // Legacy name.// 创建流fs.createReadStream = createReadStreamfs.createWriteStream = createWriteStreamvar fs$readFile = fs.readFile;fs.readFile = readFile;// 读取文件function readFile(path, options, cb) { /*...*/ }var fs$writeFile = fs.writeFile;fs.writeFile = writeFile;// 写文件function writeFile(path, data, options, cb) { /*...*/ }var fs$appendFile = fs.appendFile;if (fs$appendFile)fs.appendFile = appendFile;// 文件添加内容function appendFile(path, data, options, cb) { /*...*/ }var fs$readdir = fs.readdir;fs.readdir = readdir;// 读取目录function readdir(path, options, cb) { /*...*/ }function go$readdir(args) { /*...*/ }if (process.version.substr(0, 4) === 'v0.8') { /*...*/ }// 流处理// 可读的流var fs$ReadStream = fs.ReadStream;ReadStream.prototype = Object.create(fs$ReadStream.prototype);ReadStream.prototype.open = ReadStream$open;// 可写的流var fs$WriteStream = fs.WriteStream;WriteStream.prototype = Object.create(fs$WriteStream.prototype);WriteStream.prototype.open = WriteStream$open;fs.ReadStream = ReadStreamfs.WriteStream = WriteStreamfunction ReadStream(path, options) { /*...*/ }function ReadStream$open() { /*...*/ }function WriteStream(path, options) { /*...*/ }function WriteStream$open() { /*...*/ }function createReadStream(path, options) { /*...*/ }function createWriteStream(path, options) { /*...*/ }var fs$open = fs.open;fs.open = open;// 以某种形式打开文件function open(path, flags, mode, cb) { /*...*/ }return fs
}

function readFile(path, options, cb) {// options参数可选// 若第二参数为函数 代表省略了options参数if (typeof options === 'function')cb = options, options = null;// 调用原生的fs.readFilereturn go$readFile(path, options, cb)function go$readFile(path, options, cb) {return fs$readFile(path, options, function(err) {// 如果出错记录下来if (err && (err.code === 'EMFILE' || err.code === 'ENFILE')) {// 分别为fs模块类型 参数
                enqueue([go$readFile, [path, options, cb]])} else {if (typeof cb === 'function')cb.apply(this, arguments)retry()}})}
}// 记录错误
function enqueue(elem) {debug('ENQUEUE', elem[0].name, elem[1])queue.push(elem)
}// 重试之前产生报错的行为
function retry() {var elem = queue.shift()if (elem) {debug('RETRY', elem[0].name, elem[1])elem[0].apply(null, elem[1])}
}

// Always patch fs.close/closeSync, because we want to
// retry() whenever a close happens *anywhere* in the program.
// This is essential when multiple graceful-fs instances are
// in play at the same time.
module.exports.close =fs.close = (function(fs$close) {return function(fd, cb) {return fs$close.call(fs, fd, function(err) {// 关闭之前进行重试一次if (!err)retry()if (typeof cb === 'function')cb.apply(this, arguments)})}})(fs.close)module.exports.closeSync =fs.closeSync = (function(fs$closeSync) {return function(fd) {// Note that graceful-fs also retries when fs.closeSync() fails.// Looks like a bug to me, although it's probably a harmless one.var rval = fs$closeSync.apply(fs, arguments)retry()return rval}})(fs.closeSync)