util: trim "\x00" characters from the kernel version

It seems that convering the release component from the unix.Utsrelease
type leaves some trailing "\x00" characters.

While splitting the string to compare kernel versions, these additional
characters might prevent converting the string to an int. Strip the
additional characters before returning the string.

Note:
  "\x00" characters are not visible when printing to a file or screen.
  They can be seen in hex-editors, or sending the output through 'xxd'.

Fixes: #1167
Signed-off-by: Niels de Vos <ndevos@redhat.com>

internal/util/util.go

@@ -148,7 +148,7 @@ func KernelVersion() (string, error) {
 	if err != nil {
 		return "", err
 	}
-	return string(utsname.Release[:]), nil
+	return strings.TrimRight(string(utsname.Release[:]), "\x00"), nil
 }
 
 // GenerateVolID generates a volume ID based on passed in parameters and version, to be returned

internal/util/util_test.go

@@ -16,6 +16,7 @@ limitations under the License.
 package util
 
 import (
+	"strings"
 	"testing"
 )
 
@@ -151,4 +152,7 @@ func TestKernelVersion(t *testing.T) {
 	if version == "" {
 		t.Error("version is empty, this is unexpected?!")
 	}
+	if strings.HasSuffix(version, "\x00") {
+		t.Error("version ends with \\x00 byte(s)")
+	}
 }