使用libcurl将文件流发送到HTTP服务器

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

size_t read_callback(void* ptr, size_t size, size_t nmemb, void* userp)
{
    FILE* stream = (FILE*)userp;
    size_t retcode = fread(ptr, size, nmemb, stream);
    return retcode;
}

int main(void)
{
    CURL* curl;
    CURLcode res;
    FILE* file_stream;

    // 初始化libcurl
    curl_global_init(CURL_GLOBAL_DEFAULT);

    // 创建curl句柄
    curl = curl_easy_init();
    if (curl) {
        // 设置请求URL
        curl_easy_setopt(curl, CURLOPT_URL, "http://example.com/upload");

        // 设置请求方法为POST
        curl_easy_setopt(curl, CURLOPT_POST, 1L);

        // 设置请求头
        struct curl_slist* headers = NULL;
        headers = curl_slist_append(headers, "Content-Type: application/octet-stream");
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);

        // 打开要发送的文件流
        file_stream = fopen("file.txt", "rb");
        if (file_stream) {
            // 设置数据流
            curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback);
            curl_easy_setopt(curl, CURLOPT_READDATA, file_stream);

            // 发送请求
            res = curl_easy_perform(curl);
            if (res != CURLE_OK) {
                fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
            }

            // 关闭文件流
            fclose(file_stream);
        }

        // 清理curl句柄
        curl_easy_cleanup(curl);
    }

    // 清理libcurl
    curl_global_cleanup();

    return 0;
}