Early return when duration is non-positive

src/cpp/client/secure_credentials.cc

@@ -98,8 +98,10 @@ std::unique_ptr<Credentials> ComputeEngineCredentials() {
 std::unique_ptr<Credentials> ServiceAccountCredentials(
     const grpc::string& json_key, const grpc::string& scope,
     std::chrono::seconds token_lifetime) {
-  gpr_timespec lifetime = gpr_time_from_seconds(
+  if (token_lifetime.count() <= 0) {
-      token_lifetime.count() > 0 ? token_lifetime.count() : 0);
+    return WrapCredentials(nullptr);
+  }
+  gpr_timespec lifetime = gpr_time_from_seconds(token_lifetime.count());
   return WrapCredentials(grpc_service_account_credentials_create(
       json_key.c_str(), scope.c_str(), lifetime));
 }
@@ -107,8 +109,10 @@ std::unique_ptr<Credentials> ServiceAccountCredentials(
 // Builds JWT credentials.
 std::unique_ptr<Credentials> JWTCredentials(
     const grpc::string &json_key, std::chrono::seconds token_lifetime) {
-  gpr_timespec lifetime = gpr_time_from_seconds(
+  if (token_lifetime.count() <= 0) {
-      token_lifetime.count() > 0 ? token_lifetime.count() : 0);
+    return WrapCredentials(nullptr);
+  }
+  gpr_timespec lifetime = gpr_time_from_seconds(token_lifetime.count());
   return WrapCredentials(
       grpc_jwt_credentials_create(json_key.c_str(), lifetime));
 }