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qwen/nodejs/node_modules/random-bytes/index.js

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+/*!
+ * random-bytes
+ * Copyright(c) 2016 Douglas Christopher Wilson
+ * MIT Licensed
+ */
+
+'use strict'
+
+/**
+ * Module dependencies.
+ * @private
+ */
+
+var crypto = require('crypto')
+
+/**
+ * Module variables.
+ * @private
+ */
+
+var generateAttempts = crypto.randomBytes === crypto.pseudoRandomBytes ? 1 : 3
+
+/**
+ * Module exports.
+ * @public
+ */
+
+module.exports = randomBytes
+module.exports.sync = randomBytesSync
+
+/**
+ * Generates strong pseudo-random bytes.
+ *
+ * @param {number} size
+ * @param {function} [callback]
+ * @return {Promise}
+ * @public
+ */
+
+function randomBytes(size, callback) {
+  // validate callback is a function, if provided
+  if (callback !== undefined && typeof callback !== 'function') {
+    throw new TypeError('argument callback must be a function')
+  }
+
+  // require the callback without promises
+  if (!callback && !global.Promise) {
+    throw new TypeError('argument callback is required')
+  }
+
+  if (callback) {
+    // classic callback style
+    return generateRandomBytes(size, generateAttempts, callback)
+  }
+
+  return new Promise(function executor(resolve, reject) {
+    generateRandomBytes(size, generateAttempts, function onRandomBytes(err, str) {
+      if (err) return reject(err)
+      resolve(str)
+    })
+  })
+}
+
+/**
+ * Generates strong pseudo-random bytes sync.
+ *
+ * @param {number} size
+ * @return {Buffer}
+ * @public
+ */
+
+function randomBytesSync(size) {
+  var err = null
+
+  for (var i = 0; i < generateAttempts; i++) {
+    try {
+      return crypto.randomBytes(size)
+    } catch (e) {
+      err = e
+    }
+  }
+
+  throw err
+}
+
+/**
+ * Generates strong pseudo-random bytes.
+ *
+ * @param {number} size
+ * @param {number} attempts
+ * @param {function} callback
+ * @private
+ */
+
+function generateRandomBytes(size, attempts, callback) {
+  crypto.randomBytes(size, function onRandomBytes(err, buf) {
+    if (!err) return callback(null, buf)
+    if (!--attempts) return callback(err)
+    setTimeout(generateRandomBytes.bind(null, size, attempts, callback), 10)
+  })
+}