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-rw-r--r--dgbuilder/dgeflows/node_modules/express/node_modules/etag/index.js171
1 files changed, 171 insertions, 0 deletions
diff --git a/dgbuilder/dgeflows/node_modules/express/node_modules/etag/index.js b/dgbuilder/dgeflows/node_modules/express/node_modules/etag/index.js
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+/*!
+ * etag
+ * Copyright(c) 2014 Douglas Christopher Wilson
+ * MIT Licensed
+ */
+
+/**
+ * Module exports.
+ */
+
+module.exports = etag
+
+/**
+ * Module dependencies.
+ */
+
+var crc = require('crc').crc32
+var crypto = require('crypto')
+var Stats = require('fs').Stats
+
+/**
+ * Module variables.
+ */
+
+var crc32threshold = 1000 // 1KB
+var NULL = new Buffer([0])
+var toString = Object.prototype.toString
+
+/**
+ * Create a simple ETag.
+ *
+ * @param {string|Buffer|Stats} entity
+ * @param {object} [options]
+ * @param {boolean} [options.weak]
+ * @return {String}
+ * @api public
+ */
+
+function etag(entity, options) {
+ if (entity == null) {
+ throw new TypeError('argument entity is required')
+ }
+
+ var isStats = isstats(entity)
+ var weak = options && typeof options.weak === 'boolean'
+ ? options.weak
+ : isStats
+
+ // support fs.Stats object
+ if (isStats) {
+ return stattag(entity, weak)
+ }
+
+ if (typeof entity !== 'string' && !Buffer.isBuffer(entity)) {
+ throw new TypeError('argument entity must be string, Buffer, or fs.Stats')
+ }
+
+ var hash = weak
+ ? weakhash(entity)
+ : stronghash(entity)
+
+ return weak
+ ? 'W/"' + hash + '"'
+ : '"' + hash + '"'
+}
+
+/**
+ * Determine if object is a Stats object.
+ *
+ * @param {object} obj
+ * @return {boolean}
+ * @api private
+ */
+
+function isstats(obj) {
+ // not even an object
+ if (obj === null || typeof obj !== 'object') {
+ return false
+ }
+
+ // genuine fs.Stats
+ if (obj instanceof Stats) {
+ return true
+ }
+
+ // quack quack
+ return 'atime' in obj && toString.call(obj.atime) === '[object Date]'
+ && 'ctime' in obj && toString.call(obj.ctime) === '[object Date]'
+ && 'mtime' in obj && toString.call(obj.mtime) === '[object Date]'
+ && 'ino' in obj && typeof obj.ino === 'number'
+ && 'size' in obj && typeof obj.size === 'number'
+}
+
+/**
+ * Generate a tag for a stat.
+ *
+ * @param {Buffer} entity
+ * @return {String}
+ * @api private
+ */
+
+function stattag(stat, weak) {
+ var mtime = stat.mtime.toISOString()
+ var size = stat.size.toString(16)
+
+ if (weak) {
+ return 'W/"' + size + '-' + crc(mtime) + '"'
+ }
+
+ var hash = crypto
+ .createHash('md5')
+ .update('file', 'utf8')
+ .update(NULL)
+ .update(size, 'utf8')
+ .update(NULL)
+ .update(mtime, 'utf8')
+ .digest('base64')
+
+ return '"' + hash + '"'
+}
+
+/**
+ * Generate a strong hash.
+ *
+ * @param {Buffer} entity
+ * @return {String}
+ * @api private
+ */
+
+function stronghash(entity) {
+ if (entity.length === 0) {
+ // fast-path empty
+ return '1B2M2Y8AsgTpgAmY7PhCfg=='
+ }
+
+ return crypto
+ .createHash('md5')
+ .update(entity, 'utf8')
+ .digest('base64')
+}
+
+/**
+ * Generate a weak hash.
+ *
+ * @param {Buffer} entity
+ * @return {String}
+ * @api private
+ */
+
+function weakhash(entity) {
+ if (entity.length === 0) {
+ // fast-path empty
+ return '0-0'
+ }
+
+ var len = typeof entity === 'string'
+ ? Buffer.byteLength(entity, 'utf8')
+ : entity.length
+
+ if (len <= crc32threshold) {
+ // crc32 plus length when it's fast
+ // crc(str) only accepts utf-8 encoding
+ return len.toString(16) + '-' + crc(entity).toString(16)
+ }
+
+ // use md4 for long strings
+ return crypto
+ .createHash('md4')
+ .update(entity, 'utf8')
+ .digest('base64')
+}