9addbb57f0
Fix the random number generator by adding seed. https://stackoverflow.com/questions/12321133/golang-random-number-generator-how-to-seed-properly Jira CNA-1119 Change-Id: Idfe23d84f31a47dcf43c8025632ff6f115614d34
50 lines
1.9 KiB
Go
50 lines
1.9 KiB
Go
/*
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* Copyright (c) 2018 VMware, Inc.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
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* associated documentation files (the "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is furnished to do
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* so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all copies or substantial
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* portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
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* NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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package utils
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import (
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"math/rand"
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"time"
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)
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const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
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const (
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letterIdxBits = 6 // 6 bits to represent a letter index
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letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
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letterIdxMax = 63 / letterIdxBits // # of letter indices fitting in 63 bits
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)
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func RandStringBytesMaskImpr(n int) string {
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b := make([]byte, n)
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rand.Seed(time.Now().UTC().UnixNano())
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// A rand.Int63() generates 63 random bits, enough for letterIdxMax letters!
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for i, cache, remain := n-1, rand.Int63(), letterIdxMax; i >= 0; {
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if remain == 0 {
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cache, remain = rand.Int63(), letterIdxMax
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}
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if idx := int(cache & letterIdxMask); idx < len(letterBytes) {
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b[i] = letterBytes[idx]
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i--
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}
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cache >>= letterIdxBits
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remain--
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}
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return string(b)
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}
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