Mercurial > hg > CbC > CbC_gcc
view libgo/go/crypto/rand/rand_windows.go @ 158:494b0b89df80 default tip
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author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
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date | Mon, 25 May 2020 18:13:55 +0900 |
parents | 1830386684a0 |
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// Copyright 2010 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. // Windows cryptographically secure pseudorandom number // generator. package rand import ( "os" "sync" "sync/atomic" "syscall" "time" ) // Implemented by using Windows CryptoAPI 2.0. func init() { Reader = &rngReader{} } // A rngReader satisfies reads by reading from the Windows CryptGenRandom API. type rngReader struct { used int32 // atomic; whether this rngReader has been used prov syscall.Handle mu sync.Mutex } func (r *rngReader) Read(b []byte) (n int, err error) { if atomic.CompareAndSwapInt32(&r.used, 0, 1) { // First use of randomness. Start timer to warn about // being blocked on entropy not being available. t := time.AfterFunc(60*time.Second, warnBlocked) defer t.Stop() } r.mu.Lock() if r.prov == 0 { const provType = syscall.PROV_RSA_FULL const flags = syscall.CRYPT_VERIFYCONTEXT | syscall.CRYPT_SILENT err := syscall.CryptAcquireContext(&r.prov, nil, nil, provType, flags) if err != nil { r.mu.Unlock() return 0, os.NewSyscallError("CryptAcquireContext", err) } } r.mu.Unlock() if len(b) == 0 { return 0, nil } err = syscall.CryptGenRandom(r.prov, uint32(len(b)), &b[0]) if err != nil { return 0, os.NewSyscallError("CryptGenRandom", err) } return len(b), nil }