random: seed math/rand in one place with crypto strong seed #4783

This shouldn't be read as encouraging the use of math/rand instead of
crypto/rand in security sensitive contexts, rather as a safer default
if that does happen by accident.

cmd/cmd.go

@@ -10,7 +10,6 @@ import (
 	"context"
 	"fmt"
 	"log"
-	"math/rand"
 	"os"
 	"os/exec"
 	"path"
@@ -37,6 +36,7 @@ import (
 	"github.com/rclone/rclone/fs/rc/rcflags"
 	"github.com/rclone/rclone/fs/rc/rcserver"
 	"github.com/rclone/rclone/lib/atexit"
+	"github.com/rclone/rclone/lib/random"
 	"github.com/rclone/rclone/lib/terminal"
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
@@ -533,7 +533,9 @@ func AddBackendFlags() {
 
 // Main runs rclone interpreting flags and commands out of os.Args
 func Main() {
-	rand.Seed(time.Now().Unix())
+	if err := random.Seed(); err != nil {
+		log.Fatalf("Fatal error: %v", err)
+	}
 	setupRootCommand(Root)
 	AddBackendFlags()
 	if err := Root.Execute(); err != nil {