copy langext & termext from ffsclient

langext/rand.go

@@ -0,0 +1,38 @@
+package langext
+
+import (
+	"crypto/rand"
+	"io"
+	"math"
+	"math/big"
+)
+
+func RandBytes(size int) []byte {
+	b := make([]byte, size)
+	_, err := io.ReadFull(rand.Reader, b)
+	if err != nil {
+		panic(err)
+	}
+	return b
+}
+
+func RandBase62(rlen int) string {
+	ecs := "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
+
+	bi52 := big.NewInt(int64(len(ecs)))
+
+	randMax := big.NewInt(math.MaxInt64)
+
+	r := ""
+
+	for i := 0; i < rlen; i++ {
+		v, err := rand.Int(rand.Reader, randMax)
+		if err != nil {
+			panic(err)
+		}
+
+		r += string(ecs[v.Mod(v, bi52).Int64()])
+	}
+
+	return r
+}