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+/*!
+ * express
+ * Copyright(c) 2009-2013 TJ Holowaychuk
+ * Copyright(c) 2014-2015 Douglas Christopher Wilson
+ * MIT Licensed
+ */
+
+'use strict';
+
+/**
+ * Module dependencies.
+ * @private
+ */
+
+var contentDisposition = require('content-disposition');
+var createError = require('http-errors')
+var deprecate = require('depd')('express');
+var encodeUrl = require('encodeurl');
+var escapeHtml = require('escape-html');
+var http = require('node:http');
+var onFinished = require('on-finished');
+var mime = require('mime-types')
+var path = require('node:path');
+var pathIsAbsolute = require('node:path').isAbsolute;
+var statuses = require('statuses')
+var sign = require('cookie-signature').sign;
+var normalizeType = require('./utils').normalizeType;
+var normalizeTypes = require('./utils').normalizeTypes;
+var setCharset = require('./utils').setCharset;
+var cookie = require('cookie');
+var send = require('send');
+var extname = path.extname;
+var resolve = path.resolve;
+var vary = require('vary');
+const { Buffer } = require('node:buffer');
+
+/**
+ * Response prototype.
+ * @public
+ */
+
+var res = Object.create(http.ServerResponse.prototype)
+
+/**
+ * Module exports.
+ * @public
+ */
+
+module.exports = res
+
+/**
+ * Set the HTTP status code for the response.
+ *
+ * Expects an integer value between 100 and 999 inclusive.
+ * Throws an error if the provided status code is not an integer or if it's outside the allowable range.
+ *
+ * @param {number} code - The HTTP status code to set.
+ * @return {ServerResponse} - Returns itself for chaining methods.
+ * @throws {TypeError} If `code` is not an integer.
+ * @throws {RangeError} If `code` is outside the range 100 to 999.
+ * @public
+ */
+
+res.status = function status(code) {
+  // Check if the status code is not an integer
+  if (!Number.isInteger(code)) {
+    throw new TypeError(`Invalid status code: ${JSON.stringify(code)}. Status code must be an integer.`);
+  }
+  // Check if the status code is outside of Node's valid range
+  if (code < 100 || code > 999) {
+    throw new RangeError(`Invalid status code: ${JSON.stringify(code)}. Status code must be greater than 99 and less than 1000.`);
+  }
+
+  this.statusCode = code;
+  return this;
+};
+
+/**
+ * Set Link header field with the given `links`.
+ *
+ * Examples:
+ *
+ *    res.links({
+ *      next: 'http://api.example.com/users?page=2',
+ *      last: 'http://api.example.com/users?page=5',
+ *      pages: [
+ *        'http://api.example.com/users?page=1',
+ *        'http://api.example.com/users?page=2'
+ *      ]
+ *    });
+ *
+ * @param {Object} links
+ * @return {ServerResponse}
+ * @public
+ */
+
+res.links = function(links) {
+  var link = this.get('Link') || '';
+  if (link) link += ', ';
+  return this.set('Link', link + Object.keys(links).map(function(rel) {
+    // Allow multiple links if links[rel] is an array
+    if (Array.isArray(links[rel])) {
+      return links[rel].map(function (singleLink) {
+        return `<${singleLink}>; rel="${rel}"`;
+      }).join(', ');
+    } else {
+      return `<${links[rel]}>; rel="${rel}"`;
+    }
+  }).join(', '));
+};
+
+/**
+ * Send a response.
+ *
+ * Examples:
+ *
+ *     res.send(Buffer.from('wahoo'));
+ *     res.send({ some: 'json' });
+ *     res.send('<p>some html</p>');
+ *
+ * @param {string|number|boolean|object|Buffer} body
+ * @public
+ */
+
+res.send = function send(body) {
+  var chunk = body;
+  var encoding;
+  var req = this.req;
+  var type;
+
+  // settings
+  var app = this.app;
+
+  switch (typeof chunk) {
+    // string defaulting to html
+    case 'string':
+      if (!this.get('Content-Type')) {
+        this.type('html');
+      }
+      break;
+    case 'boolean':
+    case 'number':
+    case 'object':
+      if (chunk === null) {
+        chunk = '';
+      } else if (ArrayBuffer.isView(chunk)) {
+        if (!this.get('Content-Type')) {
+          this.type('bin');
+        }
+      } else {
+        return this.json(chunk);
+      }
+      break;
+  }
+
+  // write strings in utf-8
+  if (typeof chunk === 'string') {
+    encoding = 'utf8';
+    type = this.get('Content-Type');
+
+    // reflect this in content-type
+    if (typeof type === 'string') {
+      this.set('Content-Type', setCharset(type, 'utf-8'));
+    }
+  }
+
+  // determine if ETag should be generated
+  var etagFn = app.get('etag fn')
+  var generateETag = !this.get('ETag') && typeof etagFn === 'function'
+
+  // populate Content-Length
+  var len
+  if (chunk !== undefined) {
+    if (Buffer.isBuffer(chunk)) {
+      // get length of Buffer
+      len = chunk.length
+    } else if (!generateETag && chunk.length < 1000) {
+      // just calculate length when no ETag + small chunk
+      len = Buffer.byteLength(chunk, encoding)
+    } else {
+      // convert chunk to Buffer and calculate
+      chunk = Buffer.from(chunk, encoding)
+      encoding = undefined;
+      len = chunk.length
+    }
+
+    this.set('Content-Length', len);
+  }
+
+  // populate ETag
+  var etag;
+  if (generateETag && len !== undefined) {
+    if ((etag = etagFn(chunk, encoding))) {
+      this.set('ETag', etag);
+    }
+  }
+
+  // freshness
+  if (req.fresh) this.status(304);
+
+  // strip irrelevant headers
+  if (204 === this.statusCode || 304 === this.statusCode) {
+    this.removeHeader('Content-Type');
+    this.removeHeader('Content-Length');
+    this.removeHeader('Transfer-Encoding');
+    chunk = '';
+  }
+
+  // alter headers for 205
+  if (this.statusCode === 205) {
+    this.set('Content-Length', '0')
+    this.removeHeader('Transfer-Encoding')
+    chunk = ''
+  }
+
+  if (req.method === 'HEAD') {
+    // skip body for HEAD
+    this.end();
+  } else {
+    // respond
+    this.end(chunk, encoding);
+  }
+
+  return this;
+};
+
+/**
+ * Send JSON response.
+ *
+ * Examples:
+ *
+ *     res.json(null);
+ *     res.json({ user: 'tj' });
+ *
+ * @param {string|number|boolean|object} obj
+ * @public
+ */
+
+res.json = function json(obj) {
+  // settings
+  var app = this.app;
+  var escape = app.get('json escape')
+  var replacer = app.get('json replacer');
+  var spaces = app.get('json spaces');
+  var body = stringify(obj, replacer, spaces, escape)
+
+  // content-type
+  if (!this.get('Content-Type')) {
+    this.set('Content-Type', 'application/json');
+  }
+
+  return this.send(body);
+};
+
+/**
+ * Send JSON response with JSONP callback support.
+ *
+ * Examples:
+ *
+ *     res.jsonp(null);
+ *     res.jsonp({ user: 'tj' });
+ *
+ * @param {string|number|boolean|object} obj
+ * @public
+ */
+
+res.jsonp = function jsonp(obj) {
+  // settings
+  var app = this.app;
+  var escape = app.get('json escape')
+  var replacer = app.get('json replacer');
+  var spaces = app.get('json spaces');
+  var body = stringify(obj, replacer, spaces, escape)
+  var callback = this.req.query[app.get('jsonp callback name')];
+
+  // content-type
+  if (!this.get('Content-Type')) {
+    this.set('X-Content-Type-Options', 'nosniff');
+    this.set('Content-Type', 'application/json');
+  }
+
+  // fixup callback
+  if (Array.isArray(callback)) {
+    callback = callback[0];
+  }
+
+  // jsonp
+  if (typeof callback === 'string' && callback.length !== 0) {
+    this.set('X-Content-Type-Options', 'nosniff');
+    this.set('Content-Type', 'text/javascript');
+
+    // restrict callback charset
+    callback = callback.replace(/[^\[\]\w$.]/g, '');
+
+    if (body === undefined) {
+      // empty argument
+      body = ''
+    } else if (typeof body === 'string') {
+      // replace chars not allowed in JavaScript that are in JSON
+      body = body
+        .replace(/\u2028/g, '\\u2028')
+        .replace(/\u2029/g, '\\u2029')
+    }
+
+    // the /**/ is a specific security mitigation for "Rosetta Flash JSONP abuse"
+    // the typeof check is just to reduce client error noise
+    body = '/**/ typeof ' + callback + ' === \'function\' && ' + callback + '(' + body + ');';
+  }
+
+  return this.send(body);
+};
+
+/**
+ * Send given HTTP status code.
+ *
+ * Sets the response status to `statusCode` and the body of the
+ * response to the standard description from node's http.STATUS_CODES
+ * or the statusCode number if no description.
+ *
+ * Examples:
+ *
+ *     res.sendStatus(200);
+ *
+ * @param {number} statusCode
+ * @public
+ */
+
+res.sendStatus = function sendStatus(statusCode) {
+  var body = statuses.message[statusCode] || String(statusCode)
+
+  this.status(statusCode);
+  this.type('txt');
+
+  return this.send(body);
+};
+
+/**
+ * Transfer the file at the given `path`.
+ *
+ * Automatically sets the _Content-Type_ response header field.
+ * The callback `callback(err)` is invoked when the transfer is complete
+ * or when an error occurs. Be sure to check `res.headersSent`
+ * if you wish to attempt responding, as the header and some data
+ * may have already been transferred.
+ *
+ * Options:
+ *
+ *   - `maxAge`   defaulting to 0 (can be string converted by `ms`)
+ *   - `root`     root directory for relative filenames
+ *   - `headers`  object of headers to serve with file
+ *   - `dotfiles` serve dotfiles, defaulting to false; can be `"allow"` to send them
+ *
+ * Other options are passed along to `send`.
+ *
+ * Examples:
+ *
+ *  The following example illustrates how `res.sendFile()` may
+ *  be used as an alternative for the `static()` middleware for
+ *  dynamic situations. The code backing `res.sendFile()` is actually
+ *  the same code, so HTTP cache support etc is identical.
+ *
+ *     app.get('/user/:uid/photos/:file', function(req, res){
+ *       var uid = req.params.uid
+ *         , file = req.params.file;
+ *
+ *       req.user.mayViewFilesFrom(uid, function(yes){
+ *         if (yes) {
+ *           res.sendFile('/uploads/' + uid + '/' + file);
+ *         } else {
+ *           res.send(403, 'Sorry! you cant see that.');
+ *         }
+ *       });
+ *     });
+ *
+ * @public
+ */
+
+res.sendFile = function sendFile(path, options, callback) {
+  var done = callback;
+  var req = this.req;
+  var res = this;
+  var next = req.next;
+  var opts = options || {};
+
+  if (!path) {
+    throw new TypeError('path argument is required to res.sendFile');
+  }
+
+  if (typeof path !== 'string') {
+    throw new TypeError('path must be a string to res.sendFile')
+  }
+
+  // support function as second arg
+  if (typeof options === 'function') {
+    done = options;
+    opts = {};
+  }
+
+  if (!opts.root && !pathIsAbsolute(path)) {
+    throw new TypeError('path must be absolute or specify root to res.sendFile');
+  }
+
+  // create file stream
+  var pathname = encodeURI(path);
+
+  // wire application etag option to send
+  opts.etag = this.app.enabled('etag');
+  var file = send(req, pathname, opts);
+
+  // transfer
+  sendfile(res, file, opts, function (err) {
+    if (done) return done(err);
+    if (err && err.code === 'EISDIR') return next();
+
+    // next() all but write errors
+    if (err && err.code !== 'ECONNABORTED' && err.syscall !== 'write') {
+      next(err);
+    }
+  });
+};
+
+/**
+ * Transfer the file at the given `path` as an attachment.
+ *
+ * Optionally providing an alternate attachment `filename`,
+ * and optional callback `callback(err)`. The callback is invoked
+ * when the data transfer is complete, or when an error has
+ * occurred. Be sure to check `res.headersSent` if you plan to respond.
+ *
+ * Optionally providing an `options` object to use with `res.sendFile()`.
+ * This function will set the `Content-Disposition` header, overriding
+ * any `Content-Disposition` header passed as header options in order
+ * to set the attachment and filename.
+ *
+ * This method uses `res.sendFile()`.
+ *
+ * @public
+ */
+
+res.download = function download (path, filename, options, callback) {
+  var done = callback;
+  var name = filename;
+  var opts = options || null
+
+  // support function as second or third arg
+  if (typeof filename === 'function') {
+    done = filename;
+    name = null;
+    opts = null
+  } else if (typeof options === 'function') {
+    done = options
+    opts = null
+  }
+
+  // support optional filename, where options may be in it's place
+  if (typeof filename === 'object' &&
+    (typeof options === 'function' || options === undefined)) {
+    name = null
+    opts = filename
+  }
+
+  // set Content-Disposition when file is sent
+  var headers = {
+    'Content-Disposition': contentDisposition(name || path)
+  };
+
+  // merge user-provided headers
+  if (opts && opts.headers) {
+    var keys = Object.keys(opts.headers)
+    for (var i = 0; i < keys.length; i++) {
+      var key = keys[i]
+      if (key.toLowerCase() !== 'content-disposition') {
+        headers[key] = opts.headers[key]
+      }
+    }
+  }
+
+  // merge user-provided options
+  opts = Object.create(opts)
+  opts.headers = headers
+
+  // Resolve the full path for sendFile
+  var fullPath = !opts.root
+    ? resolve(path)
+    : path
+
+  // send file
+  return this.sendFile(fullPath, opts, done)
+};
+
+/**
+ * Set _Content-Type_ response header with `type` through `mime.contentType()`
+ * when it does not contain "/", or set the Content-Type to `type` otherwise.
+ * When no mapping is found though `mime.contentType()`, the type is set to
+ * "application/octet-stream".
+ *
+ * Examples:
+ *
+ *     res.type('.html');
+ *     res.type('html');
+ *     res.type('json');
+ *     res.type('application/json');
+ *     res.type('png');
+ *
+ * @param {String} type
+ * @return {ServerResponse} for chaining
+ * @public
+ */
+
+res.contentType =
+res.type = function contentType(type) {
+  var ct = type.indexOf('/') === -1
+    ? (mime.contentType(type) || 'application/octet-stream')
+    : type;
+
+  return this.set('Content-Type', ct);
+};
+
+/**
+ * Respond to the Acceptable formats using an `obj`
+ * of mime-type callbacks.
+ *
+ * This method uses `req.accepted`, an array of
+ * acceptable types ordered by their quality values.
+ * When "Accept" is not present the _first_ callback
+ * is invoked, otherwise the first match is used. When
+ * no match is performed the server responds with
+ * 406 "Not Acceptable".
+ *
+ * Content-Type is set for you, however if you choose
+ * you may alter this within the callback using `res.type()`
+ * or `res.set('Content-Type', ...)`.
+ *
+ *    res.format({
+ *      'text/plain': function(){
+ *        res.send('hey');
+ *      },
+ *
+ *      'text/html': function(){
+ *        res.send('<p>hey</p>');
+ *      },
+ *
+ *      'application/json': function () {
+ *        res.send({ message: 'hey' });
+ *      }
+ *    });
+ *
+ * In addition to canonicalized MIME types you may
+ * also use extnames mapped to these types:
+ *
+ *    res.format({
+ *      text: function(){
+ *        res.send('hey');
+ *      },
+ *
+ *      html: function(){
+ *        res.send('<p>hey</p>');
+ *      },
+ *
+ *      json: function(){
+ *        res.send({ message: 'hey' });
+ *      }
+ *    });
+ *
+ * By default Express passes an `Error`
+ * with a `.status` of 406 to `next(err)`
+ * if a match is not made. If you provide
+ * a `.default` callback it will be invoked
+ * instead.
+ *
+ * @param {Object} obj
+ * @return {ServerResponse} for chaining
+ * @public
+ */
+
+res.format = function(obj){
+  var req = this.req;
+  var next = req.next;
+
+  var keys = Object.keys(obj)
+    .filter(function (v) { return v !== 'default' })
+
+  var key = keys.length > 0
+    ? req.accepts(keys)
+    : false;
+
+  this.vary("Accept");
+
+  if (key) {
+    this.set('Content-Type', normalizeType(key).value);
+    obj[key](req, this, next);
+  } else if (obj.default) {
+    obj.default(req, this, next)
+  } else {
+    next(createError(406, {
+      types: normalizeTypes(keys).map(function (o) { return o.value })
+    }))
+  }
+
+  return this;
+};
+
+/**
+ * Set _Content-Disposition_ header to _attachment_ with optional `filename`.
+ *
+ * @param {String} filename
+ * @return {ServerResponse}
+ * @public
+ */
+
+res.attachment = function attachment(filename) {
+  if (filename) {
+    this.type(extname(filename));
+  }
+
+  this.set('Content-Disposition', contentDisposition(filename));
+
+  return this;
+};
+
+/**
+ * Append additional header `field` with value `val`.
+ *
+ * Example:
+ *
+ *    res.append('Link', ['<http://localhost/>', '<http://localhost:3000/>']);
+ *    res.append('Set-Cookie', 'foo=bar; Path=/; HttpOnly');
+ *    res.append('Warning', '199 Miscellaneous warning');
+ *
+ * @param {String} field
+ * @param {String|Array} val
+ * @return {ServerResponse} for chaining
+ * @public
+ */
+
+res.append = function append(field, val) {
+  var prev = this.get(field);
+  var value = val;
+
+  if (prev) {
+    // concat the new and prev vals
+    value = Array.isArray(prev) ? prev.concat(val)
+      : Array.isArray(val) ? [prev].concat(val)
+        : [prev, val]
+  }
+
+  return this.set(field, value);
+};
+
+/**
+ * Set header `field` to `val`, or pass
+ * an object of header fields.
+ *
+ * Examples:
+ *
+ *    res.set('Foo', ['bar', 'baz']);
+ *    res.set('Accept', 'application/json');
+ *    res.set({ Accept: 'text/plain', 'X-API-Key': 'tobi' });
+ *
+ * Aliased as `res.header()`.
+ *
+ * When the set header is "Content-Type", the type is expanded to include
+ * the charset if not present using `mime.contentType()`.
+ *
+ * @param {String|Object} field
+ * @param {String|Array} val
+ * @return {ServerResponse} for chaining
+ * @public
+ */
+
+res.set =
+res.header = function header(field, val) {
+  if (arguments.length === 2) {
+    var value = Array.isArray(val)
+      ? val.map(String)
+      : String(val);
+
+    // add charset to content-type
+    if (field.toLowerCase() === 'content-type') {
+      if (Array.isArray(value)) {
+        throw new TypeError('Content-Type cannot be set to an Array');
+      }
+      value = mime.contentType(value)
+    }
+
+    this.setHeader(field, value);
+  } else {
+    for (var key in field) {
+      this.set(key, field[key]);
+    }
+  }
+  return this;
+};
+
+/**
+ * Get value for header `field`.
+ *
+ * @param {String} field
+ * @return {String}
+ * @public
+ */
+
+res.get = function(field){
+  return this.getHeader(field);
+};
+
+/**
+ * Clear cookie `name`.
+ *
+ * @param {String} name
+ * @param {Object} [options]
+ * @return {ServerResponse} for chaining
+ * @public
+ */
+
+res.clearCookie = function clearCookie(name, options) {
+  // Force cookie expiration by setting expires to the past
+  const opts = { path: '/', ...options, expires: new Date(1)};
+  // ensure maxAge is not passed
+  delete opts.maxAge
+
+  return this.cookie(name, '', opts);
+};
+
+/**
+ * Set cookie `name` to `value`, with the given `options`.
+ *
+ * Options:
+ *
+ *    - `maxAge`   max-age in milliseconds, converted to `expires`
+ *    - `signed`   sign the cookie
+ *    - `path`     defaults to "/"
+ *
+ * Examples:
+ *
+ *    // "Remember Me" for 15 minutes
+ *    res.cookie('rememberme', '1', { expires: new Date(Date.now() + 900000), httpOnly: true });
+ *
+ *    // same as above
+ *    res.cookie('rememberme', '1', { maxAge: 900000, httpOnly: true })
+ *
+ * @param {String} name
+ * @param {String|Object} value
+ * @param {Object} [options]
+ * @return {ServerResponse} for chaining
+ * @public
+ */
+
+res.cookie = function (name, value, options) {
+  var opts = { ...options };
+  var secret = this.req.secret;
+  var signed = opts.signed;
+
+  if (signed && !secret) {
+    throw new Error('cookieParser("secret") required for signed cookies');
+  }
+
+  var val = typeof value === 'object'
+    ? 'j:' + JSON.stringify(value)
+    : String(value);
+
+  if (signed) {
+    val = 's:' + sign(val, secret);
+  }
+
+  if (opts.maxAge != null) {
+    var maxAge = opts.maxAge - 0
+
+    if (!isNaN(maxAge)) {
+      opts.expires = new Date(Date.now() + maxAge)
+      opts.maxAge = Math.floor(maxAge / 1000)
+    }
+  }
+
+  if (opts.path == null) {
+    opts.path = '/';
+  }
+
+  this.append('Set-Cookie', cookie.serialize(name, String(val), opts));
+
+  return this;
+};
+
+/**
+ * Set the location header to `url`.
+ *
+ * The given `url` can also be "back", which redirects
+ * to the _Referrer_ or _Referer_ headers or "/".
+ *
+ * Examples:
+ *
+ *    res.location('/foo/bar').;
+ *    res.location('http://example.com');
+ *    res.location('../login');
+ *
+ * @param {String} url
+ * @return {ServerResponse} for chaining
+ * @public
+ */
+
+res.location = function location(url) {
+  return this.set('Location', encodeUrl(url));
+};
+
+/**
+ * Redirect to the given `url` with optional response `status`
+ * defaulting to 302.
+ *
+ * Examples:
+ *
+ *    res.redirect('/foo/bar');
+ *    res.redirect('http://example.com');
+ *    res.redirect(301, 'http://example.com');
+ *    res.redirect('../login'); // /blog/post/1 -> /blog/login
+ *
+ * @public
+ */
+
+res.redirect = function redirect(url) {
+  var address = url;
+  var body;
+  var status = 302;
+
+  // allow status / url
+  if (arguments.length === 2) {
+    status = arguments[0]
+    address = arguments[1]
+  }
+
+  if (!address) {
+    deprecate('Provide a url argument');
+  }
+
+  if (typeof address !== 'string') {
+    deprecate('Url must be a string');
+  }
+
+  if (typeof status !== 'number') {
+    deprecate('Status must be a number');
+  }
+
+  // Set location header
+  address = this.location(address).get('Location');
+
+  // Support text/{plain,html} by default
+  this.format({
+    text: function(){
+      body = statuses.message[status] + '. Redirecting to ' + address
+    },
+
+    html: function(){
+      var u = escapeHtml(address);
+      body = '<p>' + statuses.message[status] + '. Redirecting to ' + u + '</p>'
+    },
+
+    default: function(){
+      body = '';
+    }
+  });
+
+  // Respond
+  this.status(status);
+  this.set('Content-Length', Buffer.byteLength(body));
+
+  if (this.req.method === 'HEAD') {
+    this.end();
+  } else {
+    this.end(body);
+  }
+};
+
+/**
+ * Add `field` to Vary. If already present in the Vary set, then
+ * this call is simply ignored.
+ *
+ * @param {Array|String} field
+ * @return {ServerResponse} for chaining
+ * @public
+ */
+
+res.vary = function(field){
+  vary(this, field);
+
+  return this;
+};
+
+/**
+ * Render `view` with the given `options` and optional callback `fn`.
+ * When a callback function is given a response will _not_ be made
+ * automatically, otherwise a response of _200_ and _text/html_ is given.
+ *
+ * Options:
+ *
+ *  - `cache`     boolean hinting to the engine it should cache
+ *  - `filename`  filename of the view being rendered
+ *
+ * @public
+ */
+
+res.render = function render(view, options, callback) {
+  var app = this.req.app;
+  var done = callback;
+  var opts = options || {};
+  var req = this.req;
+  var self = this;
+
+  // support callback function as second arg
+  if (typeof options === 'function') {
+    done = options;
+    opts = {};
+  }
+
+  // merge res.locals
+  opts._locals = self.locals;
+
+  // default callback to respond
+  done = done || function (err, str) {
+    if (err) return req.next(err);
+    self.send(str);
+  };
+
+  // render
+  app.render(view, opts, done);
+};
+
+// pipe the send file stream
+function sendfile(res, file, options, callback) {
+  var done = false;
+  var streaming;
+
+  // request aborted
+  function onaborted() {
+    if (done) return;
+    done = true;
+
+    var err = new Error('Request aborted');
+    err.code = 'ECONNABORTED';
+    callback(err);
+  }
+
+  // directory
+  function ondirectory() {
+    if (done) return;
+    done = true;
+
+    var err = new Error('EISDIR, read');
+    err.code = 'EISDIR';
+    callback(err);
+  }
+
+  // errors
+  function onerror(err) {
+    if (done) return;
+    done = true;
+    callback(err);
+  }
+
+  // ended
+  function onend() {
+    if (done) return;
+    done = true;
+    callback();
+  }
+
+  // file
+  function onfile() {
+    streaming = false;
+  }
+
+  // finished
+  function onfinish(err) {
+    if (err && err.code === 'ECONNRESET') return onaborted();
+    if (err) return onerror(err);
+    if (done) return;
+
+    setImmediate(function () {
+      if (streaming !== false && !done) {
+        onaborted();
+        return;
+      }
+
+      if (done) return;
+      done = true;
+      callback();
+    });
+  }
+
+  // streaming
+  function onstream() {
+    streaming = true;
+  }
+
+  file.on('directory', ondirectory);
+  file.on('end', onend);
+  file.on('error', onerror);
+  file.on('file', onfile);
+  file.on('stream', onstream);
+  onFinished(res, onfinish);
+
+  if (options.headers) {
+    // set headers on successful transfer
+    file.on('headers', function headers(res) {
+      var obj = options.headers;
+      var keys = Object.keys(obj);
+
+      for (var i = 0; i < keys.length; i++) {
+        var k = keys[i];
+        res.setHeader(k, obj[k]);
+      }
+    });
+  }
+
+  // pipe
+  file.pipe(res);
+}
+
+/**
+ * Stringify JSON, like JSON.stringify, but v8 optimized, with the
+ * ability to escape characters that can trigger HTML sniffing.
+ *
+ * @param {*} value
+ * @param {function} replacer
+ * @param {number} spaces
+ * @param {boolean} escape
+ * @returns {string}
+ * @private
+ */
+
+function stringify (value, replacer, spaces, escape) {
+  // v8 checks arguments.length for optimizing simple call
+  // https://bugs.chromium.org/p/v8/issues/detail?id=4730
+  var json = replacer || spaces
+    ? JSON.stringify(value, replacer, spaces)
+    : JSON.stringify(value);
+
+  if (escape && typeof json === 'string') {
+    json = json.replace(/[<>&]/g, function (c) {
+      switch (c.charCodeAt(0)) {
+        case 0x3c:
+          return '\\u003c'
+        case 0x3e:
+          return '\\u003e'
+        case 0x26:
+          return '\\u0026'
+        /* istanbul ignore next: unreachable default */
+        default:
+          return c
+      }
+    })
+  }
+
+  return json
+}