pkg/utils: Add function to get the name of the sudoers group

https://github.com/containers/toolbox/pull/318

src/pkg/utils/utils.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"os/user"
 	"sort"
 	"syscall"
 
@@ -127,6 +128,24 @@ func GetEnvOptionsForPreservedVariables() []string {
 	return envOptions
 }
 
+// GetGroupForSudo returns the name of the sudoers group.
+//
+// Some distros call it 'sudo' (eg. Ubuntu) and some call it 'wheel' (eg. Fedora).
+func GetGroupForSudo() (string, error) {
+	logrus.Debug("Looking up group for sudo")
+
+	groups := []string{"sudo", "wheel"}
+
+	for _, group := range groups {
+		if _, err := user.LookupGroup(group); err == nil {
+			logrus.Debugf("Group for sudo is %s", group)
+			return group, nil
+		}
+	}
+
+	return "", errors.New("group for sudo not found")
+}
+
 // ShortID shortens provided id to first 12 characters.
 func ShortID(id string) string {
 	if len(id) > idTruncLength {