【求助】使用cjson包后出现报内存不足的情况

发布于 2019-10-29 16:39:17 浏览：2101 订阅该版

* 本帖最后由 ssp97 于 2019-10-29 16:51 编辑 *

在使用cjson构造mqtt遗嘱的时候，出现内存不足的问题，求帮助。![微信截图_20191029163102.png](/uploads/201910/29/163627z1gawkz21km1f6r9.png)
相关cjson处理的代码如下：
```
char * cpuUuidStringGet()
{
    char *uuid;
    uuid = rt_malloc(13);
    //sprintf(uuid,"%.8X%.8X%.8X",HAL_GetUIDw0(),HAL_GetUIDw1(),HAL_GetUIDw2());
    sprintf(uuid,"%.8X%.8X%.8X",0x11223344,0x55667788,0x99AABBFF);
    return uuid;
}

char * getDeviceSn(){
    return cpuUuidStringGet();
}

cJSON * api_base(char * action)
{
    cJSON *root;

root = cJSON_CreateObject();
    cJSON_AddStringToObject(root,"device-id",getDeviceSn());
    cJSON_AddStringToObject(root,"action",action);
    return root;
}

char * api_online(char status)
{
    cJSON *root;
    char *out;

root = api_base("online");
    cJSON_AddNumberToObject(root,"data",status);
    out = cJSON_PrintUnformatted(root);
                
    cJSON_Delete(root);
    return out;
}

```mqtt启动代码片段如下：
```static char mqtt_willmsg[128];
void mq_start(void)
{
    /* 使用 MQTTPacket_connectData_initializer 初始化 condata 参数 */
    MQTTPacket_connectData condata = MQTTPacket_connectData_initializer;
    static char cid[20] = { 0 };

static int is_started = 0;
    if (is_started)
    {
        return;
    }
    /* 配置 MQTT 结构体内容参数 */
    {
        client.uri = MQTT_URI;

/* 产生随机的客户端 ID */
        rt_snprintf(cid, sizeof(cid), "rtthread%d", rt_tick_get());

/* 配置连接参数 */
        memcpy(&client.condata, &condata, sizeof(condata));
        client.condata.clientID.cstring = cid;
        client.condata.keepAliveInterval = 60;
        client.condata.cleansession = 1;
        client.condata.username.cstring = MQTT_USERNAME;
        client.condata.password.cstring = MQTT_PASSWORD;

extern char * api_online(char status);
                                char * out = api_online(0);
//                                rt_kprintf("1,%d  ",rt_strlen(out));
                                memcpy(mqtt_willmsg,out,128);
                                rt_free(out);
//                                rt_kprintf("2 ");
                        
        /* 配置 MQTT 遗言参数 */
        client.condata.willFlag = 1;
        client.condata.will.qos = 1;
        client.condata.will.retained = 0;
        client.condata.will.topicName.cstring = MQTT_PUBTOPIC;
        client.condata.will.message.cstring = mqtt_willmsg;//"abc";
                                
                                rt_kprintf("3 ");
                                
        /* 分配缓冲区 */
        client.buf_size = client.readbuf_size = 1024;
        client.buf = malloc(client.buf_size);
        client.readbuf = malloc(client.readbuf_size);
        if (!(client.buf && client.readbuf))
        {
            LOG_E("no memory for MQTT client buffer!");
            return;
        }
                                
                                rt_kprintf("4 ");
                                
        /* 设置事件回调函数 */
        client.connect_callback = mqtt_connect_callback;
        client.online_callback = mqtt_online_callback;
        client.offline_callback = mqtt_offline_callback;

/* 设置订阅表和事件回调函数*/
                                
                                //sprintf(mqtt_subtopic,"device-%s",cpuUuidStringGet());
                                
                                //rt_kprintf("mqtt:%s",mqtt_subtopic);
                                
        client.messageHandlers[0].topicFilter = "test";  //订阅主题
        client.messageHandlers[0].callback = mqtt_sub_callback;
        client.messageHandlers[0].qos = QOS2;

/* 设置默认的订阅主题*/
        client.defaultMessageHandler = mqtt_sub_default_callback;
                                rt_kprintf("5 ");
    }

/* 运行 MQTT 客户端 */
    paho_mqtt_start(&client);
                rt_kprintf("6 ");
    is_started = 1;

}
FINSH_FUNCTION_EXPORT(mq_start, startup mqtt client);
MSH_CMD_EXPORT(mq_start, startup mqtt client);
```