X-Git-Url: http://club.cc.cmu.edu/~cmccabe/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=pickrand.go;h=79c407681c7e555cd6af2d49cb03d23a3e59dddd;hb=0553471eb013b0bdd4a555c8cfddae2f68d23991;hp=a21efdaa80c8b7013e03b02bc1be5c312c4aa188;hpb=fbb7220527c04fb8b07aa777c2f46c26e35f56ed;p=cmccabe-bin

diff --git a/pickrand.go b/pickrand.go
index a21efda..79c4076 100644
--- a/pickrand.go
+++ b/pickrand.go
@@ -1,11 +1,12 @@
 package main
 
 import (
+	"bytes"
+	"crypto/rand"
 	"fmt"
+	"math/big"
 	"os"
 	"path/filepath"
-	"math/rand"
-	"time"
 )
 
 func main() {
@@ -27,7 +28,19 @@ func main() {
 		fmt.Fprintf(os.Stderr, "** Error: %s\n", err.Error())
 		os.Exit(1)
 	}
-	rand.Seed(time.Now().UTC().UnixNano())
-	i := rand.Int31n(int32(len(files)))
-	fmt.Printf("%s\n", root + "/" + files[i])
+	var b [16]byte
+	_, err = rand.Read(b[:])
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to access cryptographic randomness.  " +
+			"Error: %s\n\n", err.Error())
+		os.Exit(1)
+	}
+	i, err := rand.Int(bytes.NewReader(b[:]), big.NewInt(int64(len(files))))
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Failed to get a random int.  Error: %s\n", err.Error())
+		os.Exit(1)
+	}
+	j := int(i.Uint64())
+
+	fmt.Printf("%s\n", files[j])
 }