基于libcurl下载文件

Linux 上使用libcurl下载http文件。

需要安装libcur

apt-get install libcurl4-openssl-dev

#include <stdio.h>
#include <stdlib.h>
#include <curl/curl.h>

//判断文件是否存在
int checkRemoteRuleFileExist(const char * URL) {
 
    CURL * curl_fd = curl_easy_init();
    CURLcode code = -1;
    CURLINFO response_code = 0;
    curl_easy_setopt(curl_fd, CURLOPT_NOBODY, 1);
    curl_easy_setopt(curl_fd, CURLOPT_TIMEOUT, 3);
    curl_easy_setopt(curl_fd, CURLOPT_URL, URL);
    code = curl_easy_perform(curl_fd);

    if (code == CURLE_OK) {
        curl_easy_getinfo(curl_fd, CURLINFO_RESPONSE_CODE, &response_code);
    }

    curl_easy_cleanup(curl_fd);

    return response_code;
}

size_t write_data(void *ptr, size_t size, size_t nmemb, FILE *stream) {
    size_t written = fwrite(ptr, size, nmemb, stream);
    return written;
}

int main()
{
    char *url = "http://127.0.0.1/test.html";

    if(checkRemoteRuleFileExist(url) == 404)
    {
        printf("file not existff\n");
    }

    CURL *curl;
    FILE *fp;
    CURLcode res;
   
    char outfilename[FILENAME_MAX] = "./test.html";
    curl = curl_easy_init();
    if (curl) {
        fp = fopen(outfilename,"wb");
        curl_easy_setopt(curl, CURLOPT_URL, url);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
        res = curl_easy_perform(curl);
        /* always cleanup */
        curl_easy_cleanup(curl);
        fclose(fp);
    }
    return 0;
}

编译：

gcc main.c -lcurl