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rand.go
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rand.go
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package openssl
import (
"bufio"
"io"
"os"
"runtime"
"sync"
)
var (
// Devices ... each OS we use will have a different PRNG device,
// load based on OS.
//
Devices = map[string]string{
"test": "/dev/trandom",
"darwin": "/dev/urandom",
"linux": "/dev/TrueRNG",
}
)
// Reader - Main interface that can be passed to almost all Golang crypto
// implementations.
//
var Reader io.Reader
// init - initialize the Reader with the most effective system based
// rand generator.
//
func init() {
Reader = &devReader{name: Devices[runtime.GOOS]}
}
// devReader - satisfies reads by reading the file named name.
//
type devReader struct {
name string
f io.Reader
mu sync.Mutex
used int32
}
// Read - base read implementation for the reader. We here set our own rand
// device based on the init/os above.
//
func (r *devReader) 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()
// }
// if altGetRandom != nil && r.name == urandomDevice && altGetRandom(b) {
// return len(b), nil
// }
r.mu.Lock()
defer r.mu.Unlock()
if r.f == nil {
f, err := os.Open(r.name)
if f == nil {
return 0, err
}
if runtime.GOOS == "plan9" {
r.f = f
} else {
r.f = bufio.NewReader(hideAgainReader{f})
}
}
return r.f.Read(b)
}
var altGetRandom func([]byte) (ok bool)
var isEAGAIN func(error) bool
type hideAgainReader struct {
r io.Reader
}
func (hr hideAgainReader) Read(p []byte) (n int, err error) {
n, err = hr.r.Read(p)
if err != nil && isEAGAIN != nil && isEAGAIN(err) {
err = nil
}
return
}