Initial commit

vendor/github.com/hyperhq/hypercli/pkg/random/random.go

@@ -0,0 +1,71 @@
+package random
+
+import (
+	cryptorand "crypto/rand"
+	"io"
+	"math"
+	"math/big"
+	"math/rand"
+	"sync"
+	"time"
+)
+
+// Rand is a global *rand.Rand instance, which initialized with NewSource() source.
+var Rand = rand.New(NewSource())
+
+// Reader is a global, shared instance of a pseudorandom bytes generator.
+// It doesn't consume entropy.
+var Reader io.Reader = &reader{rnd: Rand}
+
+// copypaste from standard math/rand
+type lockedSource struct {
+	lk  sync.Mutex
+	src rand.Source
+}
+
+func (r *lockedSource) Int63() (n int64) {
+	r.lk.Lock()
+	n = r.src.Int63()
+	r.lk.Unlock()
+	return
+}
+
+func (r *lockedSource) Seed(seed int64) {
+	r.lk.Lock()
+	r.src.Seed(seed)
+	r.lk.Unlock()
+}
+
+// NewSource returns math/rand.Source safe for concurrent use and initialized
+// with current unix-nano timestamp
+func NewSource() rand.Source {
+	var seed int64
+	if cryptoseed, err := cryptorand.Int(cryptorand.Reader, big.NewInt(math.MaxInt64)); err != nil {
+		// This should not happen, but worst-case fallback to time-based seed.
+		seed = time.Now().UnixNano()
+	} else {
+		seed = cryptoseed.Int64()
+	}
+	return &lockedSource{
+		src: rand.NewSource(seed),
+	}
+}
+
+type reader struct {
+	rnd *rand.Rand
+}
+
+func (r *reader) Read(b []byte) (int, error) {
+	i := 0
+	for {
+		val := r.rnd.Int63()
+		for val > 0 {
+			b[i] = byte(val)
+			i++
+			if i == len(b) {
+				return i, nil
+			}
+			val >>= 8
+		}
+	}
+}