docs：更新文档

node_modules/resolve-path/index.js

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+/*!
+ * resolve-path
+ * Copyright(c) 2014 Jonathan Ong
+ * Copyright(c) 2015-2018 Douglas Christopher Wilson
+ * MIT Licensed
+ */
+
+'use strict'
+
+/**
+ * Module dependencies.
+ * @private
+ */
+
+var createError = require('http-errors')
+var join = require('path').join
+var normalize = require('path').normalize
+var pathIsAbsolute = require('path-is-absolute')
+var resolve = require('path').resolve
+var sep = require('path').sep
+
+/**
+ * Module exports.
+ * @public
+ */
+
+module.exports = resolvePath
+
+/**
+ * Module variables.
+ * @private
+ */
+
+var UP_PATH_REGEXP = /(?:^|[\\/])\.\.(?:[\\/]|$)/
+
+/**
+ * Resolve relative path against a root path
+ *
+ * @param {string} rootPath
+ * @param {string} relativePath
+ * @return {string}
+ * @public
+ */
+
+function resolvePath (rootPath, relativePath) {
+  var path = relativePath
+  var root = rootPath
+
+  // root is optional, similar to root.resolve
+  if (arguments.length === 1) {
+    path = rootPath
+    root = process.cwd()
+  }
+
+  if (root == null) {
+    throw new TypeError('argument rootPath is required')
+  }
+
+  if (typeof root !== 'string') {
+    throw new TypeError('argument rootPath must be a string')
+  }
+
+  if (path == null) {
+    throw new TypeError('argument relativePath is required')
+  }
+
+  if (typeof path !== 'string') {
+    throw new TypeError('argument relativePath must be a string')
+  }
+
+  // containing NULL bytes is malicious
+  if (path.indexOf('\0') !== -1) {
+    throw createError(400, 'Malicious Path')
+  }
+
+  // path should never be absolute
+  if (pathIsAbsolute.posix(path) || pathIsAbsolute.win32(path)) {
+    throw createError(400, 'Malicious Path')
+  }
+
+  // path outside root
+  if (UP_PATH_REGEXP.test(normalize('.' + sep + path))) {
+    throw createError(403)
+  }
+
+  // join the relative path
+  return normalize(join(resolve(root), path))
+}