【易开嵌入式】linux下OTA功能基于licurl使用http下载文件

易开嵌入式工作室

嵌入式系统，OTA功能是十分重要的。linux环境下，使用libcurl，通过http可以很方便实现文件下载功能，并显示文件下载进度。实现方案如下：

首先定义下载地址和下载路径

#define downLoad_url 	"http://xxxx/downloadExample/update.tar.gz"
#define downLoad_file 	"/home/xxx/update.tar.gz"

初始化libcurl并配置

CURLcode curl_base::Download(std::string strUrl,std::string filepath)
{
    CURLcode res;
    char *progress_data = "* ";  
    FILE* fp = fopen(filepath.c_str(),"wb+");

    curl_handle = curl_easy_init();

    /* send all data to this function */
    curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, OnDownLoadFile);
    /* we pass our 'chunk' struct to the callback function */
    curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)fp);

    curl_easy_setopt(curl_handle, CURLOPT_NOPROGRESS, 0L);  
    curl_easy_setopt(curl_handle, CURLOPT_PROGRESSFUNCTION, my_progress_func);  
    curl_easy_setopt(curl_handle, CURLOPT_PROGRESSDATA, progress_data);

    curl_easy_setopt(curl_handle, CURLOPT_FOLLOWLOCATION, 1);
    curl_easy_setopt(curl_handle, CURLOPT_SSL_VERIFYPEER, 0L);
    curl_easy_setopt(curl_handle, CURLOPT_SSL_VERIFYHOST, 0L);

    curl_easy_setopt(curl_handle,CURLOPT_RESUME_FROM,0);  //从0字节开始下载
    /* 设置连接超时,单位:毫秒 */
    curl_easy_setopt(curl_handle, CURLOPT_CONNECTTIMEOUT_MS, 10000L);
    curl_easy_setopt(curl_handle, CURLOPT_TIMEOUT_MS, 10000L);
    curl_easy_setopt(curl_handle, CURLOPT_NOSIGNAL, 3);
    curl_easy_setopt(curl_handle, CURLOPT_URL, const_cast<char*>(strUrl.c_str()));


    /* get it! */
    res = curl_easy_perform(curl_handle);
    /* check for errors */
    if (res != CURLE_OK) {
        fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
    }

    fclose(fp);

    return res;
}

其中，注意要关闭CURLOPT_NOPROGRESS。看下官网解释：

If onoff is to 1, it tells the library to shut off the progress meter completely for requests done with this handle. It will also prevent the CURLOPT_XFERINFOFUNCTION or CURLOPT_PROGRESSFUNCTION from getting called.

回调函数如下：

static size_t OnDownLoadFile(void* buffer,size_t size, size_t nmemb,void* fp)
{
   fwrite(buffer, size, nmemb, (FILE*)fp);
   fflush((FILE*)fp);

   return (size*nmemb);
}


static int my_progress_func(char *progress_data,
                     double t, /* dltotal */
                     double d, /* dlnow */
                     double ultotal,
                     double ulnow)
{
  printf("%s %g / %g (%g %%)\n", progress_data, d, t, d*100.0/t);
  return 0;
}

下载完成后，进行clean操作：

void curl_base::DownloadFinish()
{
    curl_easy_cleanup(curl_handle);
}

主函数：

void *myDownload_run(void *para){
	mycurl::my_curl::curl_base curl;

	curl.Download(downLoad_url,downLoad_file);
	curl.DownloadFinish();
	while(1){		
		sleep(2);
	}
}

编译后，查看运行效果：

* 271917 / 364519 (74.5961 %)
* 273365 / 364519 (74.9933 %)
* 273365 / 364519 (74.9933 %)
* 276261 / 364519 (75.7878 %)
* 276261 / 364519 (75.7878 %)
* 277709 / 364519 (76.1851 %)
* 277709 / 364519 (76.1851 %)
* 279157 / 364519 (76.5823 %)
* 279157 / 364519 (76.5823 %)
* 280605 / 364519 (76.9795 %)
* 280605 / 364519 (76.9795 %)
* 282053 / 364519 (77.3768 %)
* 282053 / 364519 (77.3768 %)
* 283501 / 364519 (77.774 %)
* 283501 / 364519 (77.774 %)
* 284949 / 364519 (78.1712 %)
* 284949 / 364519 (78.1712 %)
* 296533 / 364519 (81.3491 %)
* 296533 / 364519 (81.3491 %)
* 297981 / 364519 (81.7464 %)
* 297981 / 364519 (81.7464 %)
* 302325 / 364519 (82.9381 %)
* 302325 / 364519 (82.9381 %)
* 305221 / 364519 (83.7325 %)
* 305221 / 364519 (83.7325 %)
* 306669 / 364519 (84.1298 %)
* 306669 / 364519 (84.1298 %)
* 308117 / 364519 (84.527 %)
* 308117 / 364519 (84.527 %)
* 309565 / 364519 (84.9242 %)
* 309565 / 364519 (84.9242 %)
* 312461 / 364519 (85.7187 %)
* 312461 / 364519 (85.7187 %)
* 313909 / 364519 (86.116 %)
* 313909 / 364519 (86.116 %)
* 315357 / 364519 (86.5132 %)
* 315357 / 364519 (86.5132 %)
* 316805 / 364519 (86.9104 %)
* 316805 / 364519 (86.9104 %)
* 319701 / 364519 (87.7049 %)
* 319701 / 364519 (87.7049 %)
* 321149 / 364519 (88.1021 %)
* 321149 / 364519 (88.1021 %)
* 322597 / 364519 (88.4994 %)
* 322597 / 364519 (88.4994 %)
* 334181 / 364519 (91.6773 %)
* 334181 / 364519 (91.6773 %)
* 335629 / 364519 (92.0745 %)
* 335629 / 364519 (92.0745 %)
* 337077 / 364519 (92.4717 %)
* 337077 / 364519 (92.4717 %)
* 338525 / 364519 (92.869 %)
* 338525 / 364519 (92.869 %)
* 342869 / 364519 (94.0607 %)
* 342869 / 364519 (94.0607 %)
* 344317 / 364519 (94.4579 %)
* 344317 / 364519 (94.4579 %)
* 348661 / 364519 (95.6496 %)
* 348661 / 364519 (95.6496 %)
* 350109 / 364519 (96.0468 %)
* 350109 / 364519 (96.0468 %)
* 351557 / 364519 (96.4441 %)
* 351557 / 364519 (96.4441 %)
* 353005 / 364519 (96.8413 %)
* 353005 / 364519 (96.8413 %)
* 355901 / 364519 (97.6358 %)
* 355901 / 364519 (97.6358 %)
* 358797 / 364519 (98.4303 %)
* 358797 / 364519 (98.4303 %)
* 361693 / 364519 (99.2247 %)
* 361693 / 364519 (99.2247 %)
* 363141 / 364519 (99.622 %)
* 363141 / 364519 (99.622 %)
* 364519 / 364519 (100 %)

OK，完成！！！

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【易开嵌入式】linux下OTA功能基于licurl使用http下载文件

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