如何删除libcurl POST请求响应中收到的额外数据

我正在使用一个C程序，使用libcurl库将数据发送到PHP文件。代码如下所示：

CURL *curl;
CURLcode res;
struct curl_httppost *formpost=NULL;
struct curl_httppost *lastptr=NULL;
struct curl_slist *headers=NULL;
curl_global_init(CURL_GLOBAL_ALL);
curl = curl_easy_init();
if(curl)
{
    curl_formadd(&formpost,
        &lastptr,
        CURLFORM_COPYNAME, "name",
        CURLFORM_COPYCONTENTS, "Peter",
        CURLFORM_CONTENTTYPE, "text/plain",
        CURLFORM_END
    );
    curl_formadd(&formpost,
        &lastptr,
        CURLFORM_COPYNAME, "project",
        CURLFORM_COPYCONTENTS, "Project",
        CURLFORM_CONTENTTYPE, "text/plain",
        CURLFORM_END
    );
    curl_formadd(&formpost,
        &lastptr,
        CURLFORM_COPYNAME, "submit",
        CURLFORM_COPYCONTENTS, "Send",
        CURLFORM_END
    );
    curl_easy_setopt(curl, CURLOPT_URL, "http://maxp.biz/curl.php");
    //curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeCallback);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void*)&chunk);
    curl_easy_setopt(curl, CURLOPT_USERAGENT, "libcurl/1.0 (Linux 2.6.32.9; )");
    headers = curl_slist_append(NULL, "Content-Type: application/x-www-form-urlencoded; charset=utf-8");
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
    curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost);
    res = curl_easy_perform(curl);
    /* Check for errors */
    if(res != CURLE_OK)
    {
        DbgSerialPrn("'rcurl_easy_perform() failed: %s'n",
              curl_easy_strerror(res));
        return -1;
    }
    DbgSerialPrn("'rResult: %s'r", chunk.data);
    curl_slist_free_all(headers);
    curl_formfree(formpost);
    curl_easy_cleanup(curl);
}
else
{
    DbgSerialPrn("'rCurl Init not successful");
    return -1;
}
if(chunk.data)
{
    free(chunk.data);
}
curl_global_cleanup();

DbgSerialPrn（）方法是用于打印结果的自定义方法。当我收到PHP文件上的数据时，输出如下：

array(4) { ["_GET"]=> array(0) { }  ["_POST"]=>  array(1) {   
["--------------------------3b700fd71429022e
Content-Disposition:_form-data;_name"]=> string(323) ""name"
Content-Type: text/plain
Peter
--------------------------3b700fd71429022e
Content-Disposition: form-data; name="project"
Content-Type: text/plain
Project
--------------------------3b700fd71429022e
Content-Disposition: form-data; name="submit"
Send
--------------------------3b700fd71429022e--
"  }  ["_COOKIE"]=>  array(0) {  }  ["_FILES"]=> array(0) { }}

首先，为什么PHP文件接收的数据是一个大字符串，而不是几个单独的变量，我该如何处理它？第二，如何消除PHP文件在其$_POST数组中接收到的额外数据？