29、SNMP MIB实现与RTA参考指南

SNMP MIB实现与RTA参考指南

1. SNMP MIB实现

在操作（ACTION）阶段，我们会先检索当前值并将其保存到 saved_value 中，然后再将新值写入RTA区域表。若遇到问题，我们会返回错误。保存的值可用于撤销（UNDO）操作。

case UNDO:
    /* Back out any changes made in the ACTION case */
    sprintf(filter, "id=%d", table_index);
    sprintf(string, "%d", saved_value);
    if (saved_value != -1) {
        /* if we have a saved_value, write it back */
        if (0 != update("Zone", "enabled", filter, string)) {
            return SNMP_ERR_RESOURCEUNAVAILABLE;
        }
    }
    break;

撤销操作是将保存的值写回，但前提是操作阶段已经成功检索到旧值。

case COMMIT:
    /*
     * Things are working well, so it's now safe to make the change
     * permanently.  Make sure that anything done h