mirror of
https://github.com/autc04/Retro68.git
synced 2024-10-20 05:25:11 +00:00
57 lines
1.4 KiB
Go
57 lines
1.4 KiB
Go
// 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
|
|
}
|